US3896639A

US3896639A - Knitting machine actuators

Info

Publication number: US3896639A
Application number: US322132A
Authority: US
Inventors: Paul Christiansen; Walter A Hofmann; Werner Muller
Original assignee: Hayes-Albion Corp
Current assignee: MAYER WILDMAN INDUSTRIES Inc
Priority date: 1973-01-09
Filing date: 1973-01-09
Publication date: 1975-07-29
Anticipated expiration: 1992-07-29

Abstract

An improved knitting machine includes a plurality of interchangeable modules each of which is disposed at a knitting station and contains a vertical column of electromagnetic actuators. Each electromagnetic actuator has a generally E-shaped frame with a coil mounted on a center leg of the frame. The coil is energizable to attract an armature which has an outer end of hardened metal and is utilized to cam a needle selector jack from a knit position to a nonknit position. A pair of low friction pivot connections are formed between the armature and E-shaped frame by positioning the inner end of the armature in a pair of open recesses disposed on the outer legs of the frame. The inner end of the armature is held in the open recesses by a beam spring. The beam spring also biases the armature against movement toward an actuated position under the influence of a magnetic field emanating from the coil. Since the magnetic attraction force applied by the coil to the armature increases at an increasing rate as the armature approaches the coil, a second spring assists the beam spring in opposing movement of the armature after it has started to move toward the coil. Due to the cooperation between the two springs and the armature, the total biasing force applied to the armature increases at a greater rate toward the end of an operating stroke of the armature than at the beginning of the operating stroke to prevent excessive armature acceleration and rebound.

Description

United States Patent 1191 Christiansen et al.

[ 1 July 29, 1975 KNITTING MACHINE ACTUATORS [75] Inventors: Paul Christiansen, Novelty; Walter A. Hofmann, Lyndhurst, both of Ohio; Werner Muller, Farmington, Conn.

[73] Assignee: Hayes-Albion Corporation,

Norristown, Pa.

221 Filed: Jan. 9, 1973 121 Appl. NO.I 322,132

[52] US. Cl 156/50 R [51] Int. Cl D04b 15/78 [58] Field of Search 66/50 R, 25, 75

[56] References Cited UNITED STATES PATENTS 3,387,188 6/1968 Euler 66/50 R ux 3,518,845 7/1970 Dc Ccrjat.. 66 50 R 3,530,686 9/1970 Martinetz 66/50 R 3,550,398 12/1970 Widdowson... 66/50 R 3,605,448 9/1971 Ribler 66/75 UX 3,695,060 10/1972 Flad 66/75 3,724,240 4 1973 Flad 66/50 R 3,733,855 5/1973 BIISS-HIII ct al.. 66/50 R 3,742,733 7/1973 Pacpke 66/50 R FOREIGN PATENTS OR APPLICATIONS 1,500,569 9/1967 France 66/75 1,204,424 9/1970 United Kingdom 66/25 Primary Examiner-Wm. Carter Reynolds [57] ABSTRACT An improved knitting machine includes a plurality of interchangeable modules each of which is disposed at a knitting station and contains a vertical column of electromagnetic actuators. Each electromagnetic actuator has a generally E-shaped frame with a coil mounted on a center leg of the frame. The coil is energizable to attract an armature which has an outer end of hardened metal and is utilized to cam a needle selector jack from a knit position to a nonknit position. A pair of low friction pivot connections are formed between the armature and E-shaped frame by positioning the inner end of the armature in a pair of open recesses disposed on the outer legs of the frame. The inner end of the armature is held in the open recesses by a beam spring. The beam spring also biases the armature against movement toward an actuated position under the influence of a magnetic field emanating from the coil. Since the magnetic attraction force applied by the coil to the armature increases at an increasing rate as the armature approaches the coil, a second spring assists the beam spring in opposing movement of the armature after it has started to move toward the coil. Due to the cooperation between the two springs and the armature, the total biasing force applied to the armature increases at a greater rate toward the end of an operating stroke of the armature than at the beginning of the operating stroke to prevent excessive armature acceleration and rebound.

40 Claims, 14 Drawing Figures PATENTEDJULZSIBYS 3,896,639

' Sriiii 1 FIG! PATENTEB JUL 2 91975 21 g, FIG? V 0 %06 FIGS 5/ TENIEU JUL29 I975 S HE ET F93 Eff FLMZ Y amen/Am 1 POSITION RTURE TEA VL-Z nan/470R COIL VOLTAGE FIGIZ KNITTING MACHINE ACTUATORS BACKGROUND OF THE INVENTION This invention relates generally to a knitting machine and more specifically to a knitting machine having an electromagnetic actuator arrangement for effecting movement of a selector jack.

A circular knitting machine having needles which are moved by selector jacks is disclosed in U.S. Pat. application Ser. No. l5(),052, filed June 4. 1971 by Horst Paepke and entitled Knitting Machine, now US. Pat. No. 3,742,733. The selector jacks are moved by electromagnetic actuators which are arranged in vertical columns at each of the knitting stations. In one embodiment. the actuator includes a coil which is energized to pivot a cam member or armature into position to move a selector jack between knit and nonknit positions. In addition. knitting machines having electromagnetic jack actuators are disclosed in British Pat. No. 1.224.000, published Mar. 3. l97l and in German Pat. No. 1.585.229 having an Auslegetag date of Nov. 12. I970.

SUMMARY OF THE PRESENT INVENTION The present invention provides interchangeable actuator modules which are utilized in a knitting machine. Each of these actuator modules contains a single vertical column of electromagnetic actuator assemblies. The actuator assemblies are positioned relative to selector jack butts by engagement of outer legs of a generally E-sha'ped frame with register surfaces in a module. A coil is disposed on an inner leg of the frame and is energizable to magnetically attract a pivotal armature member. This armature member has an outer end portion formed ofa relatively hard wear resistant metal which engages the selector jack butts to cam the jacks between knit and nonknit positions.

As the armature is pivoted from an unactuated position to an actuated position under the inluence of a magnetic field emanating from the coil, the magnetic attraction force on the armature increases at an increasing rate. If unopposed, the rapidly increasing magnetic attraction force would cause excessive armature acceleration and rebound. To prevent this from occurring. a pair of spring arrangements cooperate with the armature to provide a biasing force which increases at a relatively low rate during initial movement of the armature and increases at a relatively high rate as the armature approaches the actuated position. The biasing force tends to minimize rebounding of the armature by increasing in a manner which to some extent approximates the manner in which the magnetic force of attraction on the armature increases.

The armature is pivotally connected with the outer legs of the E-shaped frame in such a manner as to tend to minimize frictional forces between the armature and frame to facilitate construction of the electromagnetic actuator assembly. The inner end of the armature is received in a pair of recesses. each of which is disposed on one of the legs of the frame. Each recess has a bottom portion and an outwardly facing opening through which the armature member extends. The only force holding the armature in the pair of recesses is provided by one of the biasing spring arrangements. This biasing spring arrangement includes a beam type spring which is connected with the two outer legs of the E-shaped frame member and the armature. To prevent excessive wear, the outer end portion of the armature is formed of a relatively hard metal.

Accordingly it is an object of this invention to provide a new and improved knitting machine having a plurality of interchangeable actuator modules in each of which electromagnetic actuators are stacked in a vertical column.

Another object of this invention is to provide a new and improved actuator assembly for use in effecting movement of knitting machine selector jacks and wherein the actuator assembly is relatively compact, has a long service life, and has an armature which is movable between unactuated and actuated positions without excessive rebound.

Another object of this invention is to provide a new an improved actuator assembly for effecting movement of a knitting machine jack between a knit and nonknit position and which includes a coil which is energizable to attract an armature with a magnetic force which increases at an increasing rate as the armature moves toward the coil, and a pair of spring arrangements which cooperate during movement of the armature to provide a biasing force which increases at an increasing rate during a final portion of the movement of the armature.

Another object of this invention is to provide a new and improved actuator assembly for effecting movement of a knitting machine jack between knit and nonknit positions and wherein the actuator assembly includes generally E-shaped frame member with a coil disposed on a center leg section and a pivotal armature connected with the outer leg sections.

Another object of this invention is to provide a new and improved knitting machine actuator assembly having an armature member which is mounted for pivotal movement from an'unactuated position to an actuated position and wherein an armature mounting arrangement includes a pair of recesses having bottom portions and openings facing toward the outer end of the armature member. and a spring to press the inner end of the armature member against the bottoms of the recesses to retain the armature member against outward movement.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other objects and features of the present invention will become more apparent upon a consideration of the following description taken in connection with the accompanying drawings wherein:

FIG. 1 is a fragmentary sectional view illustrating the relationship between a vertical column of electromagnetic actuator assemblies in an actuator module and needle selector jacks at a knitting station;

FIG. 2 is an enlarged plan view, taken generally along the line 22 of FIG. 1, illustrating the relationship between one of the actuator assemblies and positioning surfaces formed in the module;

FIG. 3 is a side elevational view of an actuator module with other portions of the knitting machine re moved for purposes of clarity of illustration;

FIG. 4 is an elevational view. taken generally along line 4-4 of FIG. 3, illustrating a front face of the module;

FIG. 5 is an elevational view taken generally along line 5-5 of FIG. 3, illustrating a rear face of the module;

FIG. 6 is a pictorial illustration of one of the electromagnetic actuator assemblies;

FIG. 7 is an enlarged plan view similar to FIG. 2 and taken generally along the line 77 of FIG. 6, illustrating the relationship between a frame. coil and armature of the actuator assembly;

FIG. 8 is a side elevational view, taken generally along the line 88 of FIG. 7, illustrating the relationship between the armature. coil and frame of the actuator assembly of FIG. 7, the armature being shown in dashed lines in an unactuated position and in solid lines in an actuated position;

FIG. 9 is an end view. taken generally along line 9-9 of FIG. 6, illustrating the relationship between the armature, a beam-type biasing spring arrangement. and a coil type biasing spring arrangement;

FIG. 10 is an enlarged fragmentary sectional view. of the area l0-10 of FIG. 8, illustrating a low friction pivot mounting arrangement for the armature;

FIG. 11 is a pictorial illustration of the frame of the actuator assembly with the coil and armature removed for purposes of clarity of illustration;

FIG. 12 is a graph illustrating the relationship between time, the duration of current pulse applied to the coil of the actuator assembly, and the position of the armature;

FIG. 13 is a graph depicting the relationship between the rate of change ofthe magnetic attraction applied to the armature by the coil and the biasing forces applied to the armature by a beam and coil spring arrangements; and

FIG. 14 is a schematic illustration of an electrical circuit for applying a current pulse to the coil of an actuator assembly.

DESCRIPTION OF ONE EMBODIMENT General Description A circular knitting machine has a plurality of knitting stations 22 (only one of which is shown in FIG. I with an actuator module 24 disposed at each of the knitting stations. The actuator module 24;includes a plurality of improved actuator assemblies 28 which are disposed in a vertical column 30 (some of the actuator assemblies have been omitted from FIG. I for purposes of clarity of illustration). Each of the actuator assemblies 28 is selectively energizable to move an associated needle selector jack 32 between knit and nonknit positions. The actuator assemblies 28 are supported in the module 24 by engagement of a generally E-shaped frame 36 (see FIGS. I and 2) with horizontally extend ing support slots 38 formed in vertically extending support walls 42 and 44 (FIG. 2).

Each of the actuator assemblies 28 includes a coil 48 which is selectively energizable to pivot an armature 52 from an unactuated position (shown in dashed lines FIG. 8) to an actuated position(shown in solid lines in FIG. 8) against the influence of a beam or bar type spring 54 (FIG. 9) and a coil spring 58. Upon initial movement of the armature 52 from the unactuated position toward the actuated position. the beam spring 54 opposes movement of the armature 52 with a biasing force which increases in a linear manner depicted by curve 64 in FIG. 13. As the armature member 52 continues to move toward the actuated position. the coil spring 58 becomes effective to apply a biasing which also increases in a linear manner. as depicted by a curve 66 in FIG. 13.

As the armature 52 moves toward the actuated position and the coil 48, at an increasing rate (see curve 68 in FIG. 13). If unopposed. this rapidly increasing magnetic force would case excessive rebounding of the armature 52 from the actuated position. The use of a single biasing spring, such as the beam spring 54, is effective to reduce the amount of armature rebound. Howe\ er. since the biasing force applied by the beam spring 54 increases in a linear manner, it is ineffective to fully compensate for the increasing rate of change of the magnetic attraction force. To more fully compensate for the increasing rate of change of the magnetic attraction force. the beam and

coil springs

54 and 58 provide a total or combined biasing force (curve 70 of FIG. I3) which increases at a greater rate toward the end of an armature stroke than the biasing force applied by only the beam spring 54. This enables the beam and

coil springs

54 and 58 to at least approximate the rate at which the magnetic attraction force (see curve 68 in FIG. 13) increases as the armatue 52 approaches the actuated position.

To enable the armature 52 to pivot freely between the unactuated and actuated positions of FIG. 8, the ar mature is provided with low friction pivot mountings which are similar to knife type bearings. The armature 52 is pivotally mounted on the frame 36 at a pair of bearing blocks 76 and 78 (FIGS-6, 7 and 9) disposed on opposite side of the coil 48. The bearing blocks 76 and 78 have outwardly opening recesses into which the armature 52 projects. Since the recesses are identical. only the recess 82 in the bearing block 78 is shown in FIGS. 8 and I0.

Knitting Needle Actuation The knitting machine 20 includes a circular needle carry cylinder (FIG. I) having a plurality of vertically extending slots 92 in which knitting needles 94 are carried. A plurality of jack arrangements 96 are mounted on the carrier cylinder 90 and are operated by the electromagnetic actuator assemblies 28 to move the associated knitting needles 94 from the illustrated knit position to anonknit position the needle cylinder 90 is rotated about a vertical central axis relative to a base I00 of the knitting machine 20. It should be understood that the term knit position may also refer to the tuck position and that the term nonknit position may refer to the welt position.

The jack arrangement 96 includes 'a needle moving jack 104 having an outer end which is pivotally connected with an associated end of one of the knitting needles 94. Each needle moving jack I04 has a butt I06 which is movable in a cam track 107 to effect raising and lowering movement of the associated knitting needle 94. In addition. each of the jack arrangements 96 includes a vertically extending selector jack 32 which is operable to effect pivoting movement of the needle raising jack I04 to remove the butt I06 thereof from the cam track I07 so that the needle will not be raised through a knitting stroke as it moves through a knitting station 22.

Each of the selector jacks 32 has a butt I14 which may be engaged by the armature 52 of an associated one of the electromagnetic actuator assemblies 28 during movement of the jack butt through the knitting station 22. Engagement with the armature 52 pivots the selector jack 32 in a counterclockwise direction about its lower end portion 118 and effects movement of the butt I06 of the needle jack I04 out of the cam track 107. In the specific embodiment of the invention illustrated in the drawings. the selector jacks 32 are deposited in echelon groups of thirteen jacks with the butts 114 of the jacks offset vertically. There are I3 electromagnetic actuator assemblies 28 in each actuator module 24. Each of the actuator assemblies 28 is associated with the jack butts 114 at a particular level. Thus. dur ing rotation of the needle cylinder 90, the uppermost electromagnetic actuator assembly 28 is operable to engage the uppermost butt I14 in an echelon group of selector jack butts. Similarly. the next lower actuator assembly 28 engages the next lowerjack butt in an echelon group.

The operation of the selector jack 32 and needle jacks 104 in association with each one of the knitting needles 94 is more thoroughly described in the aforementioned U.S. Pat. application Ser. No. 150.052. filed June 4. I97] by Horst Paepke. The controls for activating the electromagnetic actuator assemblies 28 to move the associated one of the jack butts 114 between the knit and nonknit positions are the same as disclosed in US. Pat. application Ser. No. 193.047. filed Oct. 27. 1971 by Paul Christiansen and entitled Knitting Machine Control." An encoder arrangement similar to the one disclosed in application Ser. No. 192,984. filed Oct. 27. I971 by Ralph H. Schuman and entitled Knitting Machine Encoder" is used in association with these controls. Although the jack arrangement and controls disclosed in these applications are preferred for use with the electromagnetic actuator assemblies 28, it should be understood that other jack arrangements and controls be utilized if desired.

Although only a single knitting station 22 is shown in FIG. I. it should be understood that the knitting machine includes a plurality of knitting stations disposed in an annular array about the rotatable needle cylinder 90. At each of these knitting stations is disposed one of the stationary actuator modules 24. Since the actuator modules 24 are of identical construction and cooperate with the jack arrangements 96 in the same way. the actuator modules are interchangeable. Only one of the actuator modules 24 has been shown in FIG. I.

In one specific embodiment of the invention. the circular knitting machine 20 had 1,872 needles arranged in I44 echelons of 13 needles each. This illustrative knitting machine had 36 knitting stations 22 with an actuator module 24 containing I3 actuator assemblies 28 at each of the knitting stations. Since each actuator assembly 28 is operable to engage the butt 114 of only one selector jack 32 in each echelon of 13 selector jacks. the actuator assembly 28 must be capable of operating with sufficient speed to move the armature 52 between the unactuated and actuated positions in less time than it takes thirteen needles 94 to move past a knitting station. The available actuation time is determined by relating the speed of rotation of the cylinder 90-to the distance between I3 needles minus the width of the armature. It should be understood that although the electromagnetic actuator assemblies 28 are described herein in connection with a knitting machine 20 having 13 needles in each echelon. the actuator assemblies could be utilized in association with a knitting machine having a greater or lesser number of needles in each echelon.

Actuator Module Each of the actuator modules 24 (FIG. 3) includes a bottom section I20 and an upstanding support section 122 in which the actuator assemblies 28 are disposed in a vertically extending array (FIG. I). The upstanding support section 122 positions each of the electromagnetic actuator assemblies 28 so that the armatures 52 are disposed slightly below the associated jack butt 1 14 in each echelon group ofjack butts when the armature is in the unactuatedposition (shown in dash lines in FIG. 8). This enables the selector jack 32 associated with an unactuated electromagnetic actuator assembly 28 to move through the knitting station without being cammed from the knit position of FIG. I to the nonknit position. However, when the,coil 48 of an actuator assembly 28 is energized. the armature 52 pivots upwardly into the path of movement of the butt 114 of the associated selector jack 32. Therefore, the butt 114 of the selector jack 32 associated with the actuated electromagnetic actuator assembly 28 is cammed to the nonknit position as it is moved through the knitting station 22.

To hold the actuator assemblies 28 in a vertical columnor array. the upstanding support section 122 of the actuator module 24 includes a pair of vertically extending side walls 126 and 128 (see FIGS. 2 and 4). The

support walls

126 and 128 are each provided with horizontally extending slots 38 (FIGS. l and 2) which receive the frames 36 of the electromagnetic actuator assemblies 28 and support the actuator assemblies with the central or main axes of the coils 48 extending horixontally in a common vertical plane. The slots 38 also function to locate the actuator assemblies 28 in the proper vertical relationship with the selector jacks 32.

The actuator assemblies 28 must be positioned so that the outer end portions of the armatures 52 engage the butts I14 of the selector jacks after the armatures are moved from their unactuated positions to their actuated positions. To provide for this positioning of the actuator assemblies 28. the forward ends of the frames 36 of the actuator assemblies are engaged by a pair of vertically extending front positioning or register blocks I34 and 136 (FIG. 2) which are connected to the

side walls

126 and 128 and have a transversely inwardly projecting register surface I40 and 142 which engage the forward or outer end portions of the frames 36. The frames 36 are pressed against the vertical register surfaces 140 and 142 by a vertically extending rear positioning block 146 having a pair of

side sections

148 and 150 which engage the inner ends of the frames 36 to hold the frames in engagement with the register surfaces 140 and 142. A slotted shield or cover member 154 is provided on the front or forward side of the actuator module 24 to prevent foreign material from interferring with the operation of the actuator assemblies 28.

Once the actuator assemblies 28 have been positioned within the module 24. it is necessary to position the module at one of the knitting stations 22 in the desired orientation relative to the needle cylinder 90 and selector jacks 32. To this end. a register plate 158 (see FIGS. 1, 3. 4 and 5) is fixedly mounted at each of the knitting stations. A locating slot 160 (FIGS. 4 and 5) is formed in the register plate 158 and extends radially of the carrier cylinder 90. The bottom portion 120 of the module frame is provided with a locating tongue 162 which engages the slot 160 to position the module 24 along one axis.

Each of the modules 24 is provided with a locating or positioning screw I66 (see FIGS. 3 and 4) which engages a surface 168 (FIG. I) to position the module along an axis extending radially to the carrier cylinder 90. Once the locating tongue 162 has been positioned in a slot 160 and the positioning screw 166 has engaged the register surface 168. the module 24 is located in the proper position relative to the actuator jack arrange ment 96. When the module 24 has been so positioned, a bolt 172 (see FIG. I) is tightened to securely connect the module 24 with the base 100 of the knitting machine.

Although the construction ofonly one actuator mod ule 24 has been shown in the drawings. it should be understood that the knitting machine 20 includes a plurality of actuator modules 24 of identical construction which are disposed in a circular array about the carrier cylinder 90 with one of the actuator modules 24 being located at each of the knitting stations. The actuator assemblies 28 in the actuator modules 24 are connected with electrical leads 176 which are enclosed in a cable 178 having a plug 180 (FIG. 1) connected with control circuitry for the knitting machine. After a module 24 has been removed from a knitting station 22, the identical construction of the modules enables a spare module to be positioned at the knitting station.

Once the actuator module 24 has been removed from the knitting station 22, a cover 184 is removable to provide access to the interior of the module. Each of the actuator assemblies 28 is connected with the electrical leads 176 by a plug 188 (FIG. 2) and connector jacks 190 and 192. The jacks I90 and 192 extend through the positioning member 146 into engagement with an electrical connector 194 which is connected directly to the coil 48.

Actuator Assembly Frame Each of the actuator assemblies 28 includes a generally E-shaped frame 36 (see FIG. 11) which is stamped from a single piece of slicon core iron which is readily magnetized by energization of a coil 48 (FIG. 7) and has a low residual magnetism when the coil is deenergized. The frame 36 includes a relatively long center leg 200 (FIG. 11) which extends through the center of the coil 48. A pair of

side legs

204 and 206 are disposed on opposite sides of the center leg 200 and extend parallel to the center leg. The

side legs

204 and 206 are slightly shorter in length than the center leg 200 so that the bearing blocks 76 and 78 which pivotally support the armature 52 can be mounted on the ends of the side legs (see FIG. 7) with the center leg 200 extending outwardly of the bearing blocks. This enables the center leg 200 to overlie the armature 52 and provide a strong magnetic interconnection between the armature and frame 36 upon energization of the coil 48.

The

side legs

204 and 206 of the frame 36 are provided with positioning projections 220., 222, 224 and 226 (FIG. 7) engage the bottom of the slots 38 in the

side walls

126 and 128 of the actuator module 24 (FIG. 2) to position the frame 26 transversely relative to the side walls. The frame 36 is also provided with a rearwardly projecting positioning section 230 which is engaged by the positioning member 146 to press the outer end portions 210 and 212 (FIG. 11) of the frame 36 against the register surfaces 140 and 142 (FIG. 2). Thus. the integrally formed frame member 36 is provided with positioning sections which are utilized to locate the actuator assembly 28 along a horizontal central axis which extends radially from the needle cylindcr 90 and along a horizontal axis extending perpendicular to this radial axis. Armature Mounting To minimize frictional resistance to pivotal movement of the armature 52 between the unactuated position (shown in dashed lines FIG. 8) and the actuated position (shown in solid lines in FIG. 8), the armature is connected with the frame 36 at low friction bearing connections 232 and 233 (FIGS. 7 and 9) which are similar to knife edge bearings and have a long service life. The generally knife type bearing connections are formed between outwardly projecting

side arm sections

234 and 236 of the armature 52 and the bearing support blocks 76 and 78. The connection 232 between the arm section 236 and the bearing support block 78 is clearly set forth in FIG. 10 wherein the armature 52 is shown in dashed lines in an unactuated position and in solid lines in the actuated position. When the armature 52 is in the unactuated position. a first corner of apex 240 formed by the intersection of a bottom or major surface 242 and a rear or minor surface 244 engages a flat bottom surface 248 of the recess 82. Upon energization of a coil 48 and movement of the armature 52 to the actuated position (shown in solid lines in FIG. 10) the end surface 244 of the armature 52 is disposed in flat abutting engagement with the bottom surface 248 of the recess 82. This flat abutting engagement between the end surface 244 of the armature 52 and bottom surface 248 of the recess 82 provides a relatively large surface area to transmit shock loading applied to the armature 52 by engagement with a jack butt 114. A true knife edge bearing could be damaged by such a loading. Of course. upon de-energization of the coil 48 the armature pivots about the corner 240 from the actuated position to the unactuated position.

Although the connection between the armature 52 and bearing block 78 may not be considered as a true knife edge bearing due to the fact that the end surface 244 of the armature moves into flat abutting engagement with the bottom surface 248 of the recess 82 when the armature 52 is in the actuated position. the connection between the armature 52 and bearing block 78 provides most if not all of the advantages of a true knife edge bearing. Thus. there is a relatively low friction force opposing movement of the armature S2 relative to the bearing block 78. In addition. the simple interconnection between the armature 52 and bearing block 78 is relatively trouble free so that the actuator assembly 28 has a relatively long service life with a minimum amount of maintenance. Although only the interconnection between the armature 52 and the bearing block 78 is shown in FIG. 10. it should be understood that the arm 234 of the armature member 52 has a second corner or apex and cooperates with the bearing block 76 in the same manner as in which the arm 236 cooperates with the bearing block 78.

The beam type spring 54 urges the inner end portions of the

arms

234 and 236 into abutting engagement with the recesses 82 in the bearing blocks 76 and 78. Thus. a connector arm or hook 252 extends downwardly from the center portions of the armature 52 (see FIGS. 9 and 10) into engagement with the beam spring 54. The beam spring 54 applies a force to the connector arm or hook 252 urging the armature 52 toward the right (as viewed in FIG. 10). This force presses the inner or rearward end of the armature 52 against the bottom 248 of the recess 82. It should be noted that the recess 82 has a generally rectangular opening having a vertical extent which is greater than the thickness of the armature 52 so that the armature can be moved freely into and out of the recess. However. the beam spring maintains the inner end of the armature 52 in abutting engagement with the bottom 248 of the recess 82. The vertically extending bottom surface 248 of the recess has a vertical height which is only slightly greater than the thickness of the armature 52 so that the inner end of the armature can lay flat against the bottom surface 248. The recess 82 is provided with a downwardly sloping lower side surface 260 which is engaged by the lower surface 242 of the armature 52 when it is in the unactuated position.

The beam spring 54 includes a pair of generally straight longitudinally extending spring rods or wires 266 and 268 (FIG. 9) which extend through a pair of passages formed by

holddown tabs

272 and 274. The

spring rods

266 and 268 are resiliently deflected upwardly by a relatively small amount when the armature 52 is in the unactuated position (shown in dashed lines in FIG. 8). Upon pivotal movement of the armature 52 to the actuated position (shown in solid lines in FIG. 8) the connector hook or arm 252 increases the deflection of the

spring rods

266 and 268 through the movement of the connector arm 252 relative to a pair of

support plates

278 and 280 in which the

holddown tabs

272 and 274 are formed and to which the ends of the

spring rods

266 and 268 are connected. The

support plates

278 and 280 are connected to the bottom of the outer frame arms 204 and 206 (FIG. 6). One of the support plates. that is the support plate 280, has an outwardly projecting stop arm 284 which limits downward movement of the armature 52 during handling of the actuator assembly 28 outside of the module 24.

To reduce the passage of magnetic flux from the

outer legs

204 and 206 to the center leg 200 (FIG. 11) of the frame 36 without passing through the armature 52, the

support plates

278 and 280 are formed of a nonmagnetic material. such as stainless steel. The passage offlux from the

outer frame legs

204 and 206 to the armature 52 is promoted by the beam spring 54. The

beam spring rods

266 and 268 are formed of a magnetizable material and extend from a location adjacent to the ends of the

outer frame legs

204 and 206 to the connector arm 252 which is integrally formed with the armature 52 (FIG. 9). This provides a minimum air gap between the armature 52 and

outer frame legs

204 and 206 to promote the passage of flux to the armature. Armature Movement Upon energization of the coil 48, the armature 52 moves from an unactuated position (indicated by the portion 304 of the curve 290 in FIG. 12) toward a fully actuated position indicated by portion 292 of the curve 290. Before the armature reaches the fully actuated position. it reaches a position in which the outer end portion of the armature will interfere with the butt 114 of an associated selector jack 32. this position being indicated by the line 296 in FIG. 12. As the armature 52 moves upwardly toward the actuated position. it engages an upper stop surface 287 formed on the slotted shield or cover member 154 (FIG. 8). and tends to rebound in the manner indicated by the irregular line 298 (FIG. I2). However. this rebound is not great enough to cause the armature 52 to move to a position in which it will not engage the jack butt H4. To tend to minimize armature rebound. the shield I54 is formed of an energy absorbing material. such as synthetic rubber. Of course. other known energy absorbing material could be used if desired.

If the next needle 94 is to be cammed to the nonknit position, the actuator assembly 28 remains energized. However, if the next needle is to knit. the coil 48 is deenergized and the armature 52 moves downwardly from the actuated position toward the unactuated position in a manner represented by the portion 300 of the curve 290 (FIG. 12). As the armature moves downwardly. it moves to a position (represented by line 304 in FIG. I2) in which it is substantially below the associated jack butt 114 and will not interfere with the next succeeding jack butt. As the armature 52 reaches the unactuated position it engages a lower stop surface 288 on the shield 154 (FIG. 8) and tends to rebound, as indicated by the irregular line 306. Of course. the lower stop surface 288 is also made of an energy absorbing material so that rebounding of the armature is minimized.

To effect rapid movement of the armature 52 from the unactuated position to the actuated position. a relatively high forcing voltage (V,) is supplied to the coil 48 in the manner illustrated by the portion 307 of the curve 308 in FIG. 12. This relatively high forcing voltage is then reduced to a holding voltage (V,,) indicated by the portion 309 of the curve 308. The relatively high initial forcing voltage causes the current connected to the coil 48 to quickly increase in the manner shown by the portion 310 of the curve 31] in FIG. 12. Of course. once the voltage applied to the coil 48 decreases to the holding voltage (indicated by the portion 309 of the curve 308) the current flow through the coil 48 reduces to a holding value indicated by the portion 312 of the curve 311.

Upon de-energization of the coil 48. the collapsing of the magnetic field causes an instantaneous negative voltage. indicated by the portion 313 of the curve 308. As the coil voltage returns to zero. the current flow through the coil drops to Zero as shown in the portion 314 of the curve 311. This results in the armature S2 returning to the unactuated position under the influence of the beam spring 54 and coil spring 58. It should be noted that the upper surface 287 prevents the armature 52 from striking the center leg 200 of the frame 36 to prevent wear and magnetic sealing between the frame and armature.

As the armature 52 moves from the unactuated position to the actuated position. the force of magnetic attraction applied to the armature by magnetic field emanating from the coil 48 increases in a nonlinear manner. Thus. during initial movement of the armature 52 from the unactuated position. the force of magnetic attraction applied to the armature increases at a relative low rate. However. as the armature approaches the center leg or pole piece 200 of the coil 48, the force of magnetic attraction increases at an increasing rate in the manner depicted schematically by the curve 68 in FIG. 13.

The biasing force applied by the beam spring 54 resisting movement of the armature from the unactuated position to the actuated position increases at a constant rate with movement of the armature from the unactuated position toward the actuated position. This is because the amount of deflection of the beam spring 54 increases at a constant rate with movement of the armature 52 toward the actuated position. During initial movement of the armature 52 from the unactuated position toward the actuated position. the biasing force applied to the armature by the beam spring 54 is somewhat less than magnetic attraction force and increases in a manner which is generally similar to the manner in which the magnetic attraction force applied to the armature increases. Thus. during initial movement of the armature 52, the beam spring force. represented by the line 64 in FIG. 13, increases in a manner generally similar to the manner in which the magnetic attraction force increases, shown by the curve 68 in FIG. 13.

Approximately midway through the travel of the armature 52. the magnetic attraction force begins to increase at a substantially greater rate than the rate which the beam spring force increases. Due to the rela tively rapid rate of increase in the magnetic attraction force. if only the beam spring arrangement 54 applied a biasing force to the armature 52, the armature would accelerate greatly as it moved toward the actuated position. This acceleration would increase the rebound of the armature from the actuated position.

To prevent excessive rebound of the armature from the actuated position, the coil spring 58 becomes effective to apply a biasing force to thc armature part way through an operating stroke. The force applied to the armature by the coil spring 58 is represented by the line 66 in FIG. 13. Due to the influence of the coil spring 58 which circumscribes spring guide 315, the total biasing force applied to the armature 52 increases at an increasing rate as the armature approaches the actuated position represented by the lines 316 in FIG. 13. Due to the biasing effect applied by the coil spring 58, the acceleration of the armature 52 is retarded so that it does not rebound excessively from the actuated position. It should be noted that the coil spring 58 is not effective until the armature has travelled part way between the actuated and unactuatcd positions, represented by the lines 318 in FIG. 13. At this time the lower end portion of the coil spring 58 engages the bottom ofa recess 320 (FIG. 9) formed in the armature 52 and is effective to regard movement of the armature in conjunction with the beam type biasing spring 54. The energy stored in the coil spring 58 enables it to promote rapid movement of the armature 52 from the actuated position to the unactuated position.

A circuit 324 (FIG. 14) provides a pulse of current (represented by the curve 308 in FIG. 12) to energize coil 48. The circuit 324 includes a lead 326 which is connected with a positive voltage source and the coil 48. The coil 48 is connected to ground through a transistor 328. The transistor 328 is rendered conducting by a signal 329 (FIG. 12) transmitted to the base of the transistor 328 by control circuitry connected with a lead 330 when the coil 48 is to be energized to effect movement of a selector jack 32 from the knitting position to the nonknitting position.

To provide a relatively large forcing voltage. represented by the portion 307 of the curve 308 of FIG. 12. the circuit 324 (FIG. 14) is provided with a capacitor 331 which is charged with a relatively high forcing voltage while the transistor 328 is turned off. Thus. the capacitor 331 is connected with a relatively high voltage source (V through resistor 332. The charge rate for the capacitor 331 is such that the capacitor will charge to a sufficiently high voltage when the actuator is being operated at the maximum rate required for a particular machine. In one specific embodiment of the invention (ill the forcing voltage (V was approximately four to five times the holding voltage (V,,).

When the transistor 320 is turned on by the signal 329 (FIG. 12) directed to the base of the transistor. the relative high forcing voltage (V on the capacitor 331 appears across the actuator coil 48 as indicated by the portion 307 of the curve 308 in FIG. 12. This causes the current to build up rapidly (see portion 310 of the curve 311 in FIG. 12). When the charge on the capacitor 331 has been reduced. the holding voltage (V,,) is supplied through a diode 333 to the coil -88 (see portion 312 of the curve 311 in FIG. 12). Although some of the holding current is supplied by the forcing voltage source (V through the resistor 332. this current is not sufficient to hold the armature 52 in the actuated position. A diode 334 limits the voltage at the collector of the transistor 328 to the forcing voltage (V when the transistor 328 is turned off and the actuator field 48 collapses.

When the armature 52 is in the actuated position. an outer end portion 340 (see FIG. 7) is disposed in the path of movement of a jack butt 114 which is in a particular position in the echelon formation of jack butts. The outer end portion of the armature S2 is formed of a relatively hard tool steel to enable it to withstand wear induced by engagement with the jack butts 114. The remainder of the armature 52 is formed of a relativcly soft material. such as low carbon I .010 steel) to provide a relatively low residual magnetism upon deenergization of the coil 48.

Since the

arms

234 and 236 of the armature 52 are disposed in pressure engagement with the outwardly opening recesses 82 in the bearing blocks 76 and 78. it is advantageous to have the force applied to the armature 52 by engagement with one of the jack butts 114 which tends to cause the armature to pivot about a center disposed between the two bearing blocks 76 and 78. If the armature 52 tended to pivot about a center disposed outwardly of one of the bearing blocks. the armature would tend to move away from the other bearing block. For example. if the force is applied to the armature 52 by engagement with one of the jack butts I14 resulted in a moment of torque tending to pivot the armature about a center disposed to the outer side of a bearing block 76. the arm 236 of the armature would tend to move away from the bearing block 78.

To tend to minimize movement of the armature arm 236 away from the bearing block 78 when the armature engages a jack butt 114. the armature 52 has a main or body portion 344 extending outwardly from the

arms

234 and 236 for a short distance. A cam surface 348 on the outer end of the body 344 is disposed at an angle (indicated at 350 in FIG. 7) of between 13 and 25. The combination of the relatively short body portion and cam angle results in the armature 52 tending to pivot about a center which is located between the bearing blocks 76 and 78 when the cam surface 348 engages a jack butt 114. Therefore. the arm 236 of the armature does not tend to move away from the bearing block 78.

Due to friction between the armature S2 and cam surface on an associated jack butt 114 and/or other causes. the armature 52 may tend to rotate about a center outside of the bearing block 76. If this occurs. the armature 52 is engaged by a hardened steel stop block or panel 351 (FIG. 4) to prevent the armature arm 236 from moving out of the recess in the bearing block 78.

In one specific embodiment of the invention the clearance between the armature 52 and stop panel 351 was between 0.001 and 0.002 of an inch. It should be understood that the foregoing dimensions are merely illustrative and could vary.

The actuator assembly 28 at the top of the column 30 (FIG. 1) of actuator assemblies must move a selector jack butt 114 through a larger distance than an actuator assembly 28 at the bottom of the column 30. This is because the selector jacks 32 pivot about their lower end portions 118 when they move from the knit position to the nonknit position. Accordingly. the cam angle 350 on an armature 52 at the top of the column 30 is greater than the cam angle on an armature at the bottom of the column. The jack butts 114 associated with actuator assemblies 28 adjacent to the top of the column 30 project further from the body of the selector jack 32 than do the jack butts 114 associated with actuator assemblies adjacent to the bottom of the column.

In one specific embodiment of the invention, the cam angle 350 on the armature 52 of the actuator assembly 28 at the top of the column 30 was The cam angle on the armatures 52 of the actuator assemblies 28 between top and bottom of the column decreased in a proportional manner to a cam angle of 13 at the bottom of the column. The extent to which the selector jack butts 114 projected also decreased in a uniform manner from a relatively large projection for the uppermost jack butt of an echelon group of jack butts to a relatively small projection for the lowermost jack butt in the echelon group ofjack butts. Ofcourse, other specific cam angles could be utilized as required. Conclusion In view of the foregoing description. it will be seen that the knitting machine 20 includes a plurality of interchangeable actuator modules 24 each of which is disposed at one of a plurality of knitting stations 22.

The actuator modules 24 are of identical construction'--.

and contain a single vertical column or array ofelectromagnetic actuators 28. Each of these electromagnetic actuators 28 has a generally E-shaped frame 36 with

outer legs

204 and 206 disposed in engagement with register surfaces 140 and 142 to position an actuator assembly 28 in the module 24. A coil 48 is mounted on a horizontal center leg of the E-shaped frame member 36 and is energizable to attract an armature 52 which has an outer end portion 340 of a hardened metal to cam a needle selector jack 32 from a knit position to a nonknit position.

A pair of

arms

234 and 236 of the armature member 52 have inner end portions disposed in a pair of open recesses 82 formed in bearing blocks 76 and 78 mounted on outer ends of the

legs

104 and 206 of the frame member 36. Although the sides of the recesses 82 are spaced apart by a sufficient distance to enable the armature 2 to be freely withdrawn from the recesses, the armature is held in the recesses by a beam spring 54. Since the magnetic force applied by the coil 48 to the armature 52 increases at an increasing rate as the armature approaches the coil, a second spring 58 assists the beam spring 54 in opposing movement of the armature after the armature has started to move toward the coil 48. Due to the cooperation between the two

springs

54 and 58. the total biasing force applied to the armature 52 by the springs increases at a greater rate toward the end of the operating stroke of the armature than at the beginning of the stroke.

Having described one specific preferred embodiment of the invention, the following is claimed:

1. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station, a plurality of jack means each of which is associated with one of said needles and is operable between knit and nonknit conditions, and a plurality of actuator means disposed at the knitting station for effecting operation of said jack means between the knit and nonknit conditions, each of said actuator means including coil means energizable to provide a magnetic field, a frame member having a plurality of parallel interconnected leg sections including a first leg section extending through said coil means, a second leg section disposed on one side of said first leg section, and a third leg section disposed on a side of said first leg section opposite said one side, an armature member movable under the influence of a magnetic field emanating from said coil means, and mounting means connected with said second and third leg sections for supporting said armature member for pivotal movement between a first position in which said armature member is ineffective to operate one of said jack means between the knit and nonknit conditions and a second position in which said armature member is ef fective to operate one of said jack means between the knit and nonknit conditions, the magnetic field emanating from said coil means of each of said actuator means being effective upon energizati'on thereof to attract said armature member with a magnetic force which increases at an increasing rate as said armature member moves between the first and second positions. each of said actuator means further including first spring means for providing a first biasing force opposing movement of said armature member between the first and second positions under the influence of the magnetic field emanating from said coil means. and second spring means for providing a second biasing force which is effective to oppose movement of said armature member after said armature member has moved part way between said first and second positions against the influence of said first biasing force. said first and second spring means cooperating during movement of said armature member to provide a total biasing force which increases at a first rate during an initial portion of the movement of said armature member between the first and second positions and which increases at a second rate which is greater than the first rate during a final portion of the movement of said armature member between the first and second positions.

2. A knitting machine as set forth in cliam 1 further including support means for supporting said actuator means in a linear array at the knitting station, said support means including a first longitudinally extending support element connected with the second leg section of said frame members and a second longitudinally extending support element connected with the third leg section of said frame members.

3. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station. a plurality of jack means each of which is associated with one of said needles and is operable between knit and nonknit conditions. and a plurality of actuator means disposed at the knitting station for effecting operation of said jack means between the knit and nonknit conditions, each of said actuator means including coil means energizable to provide a magnetic field, a frame member having a plurality of parallel interconnected leg sections including a first leg section extending through said coil means. a second leg section disposed on one side of said first leg section, and a third leg section disposed on a side of said first leg section opposite said one side. an armature member movable under the influence of a magnetic field emanating from said coil means, mounting means connected with said second and third leg sections for supporting said armature member for pivotal movement between a first position in which said armature member is ineffective to operate one of said jack means between the knit and nonknit conditions and a second position in which said armature member is effective to operate one of said jack means between the knit and nonknit conditions, and spring means for providing a biasing force opposing movement of said armature member between the first and second positions, said spring means including a beam spring member extending transversely to said leg sections and having a central porition connected to said armature member, one end portion connected with said second leg section, and another end portion connected with said third leg section.

4. A knitting machine as set forth in claim 3 wherein said mounting means for each of said actuator means includes a first recess means connected with said second leg section for engaging an inner end portion of said armature member at one location and a second recess means connected with said third leg section for engaging the inner end portion of said armature member at another location spaced from the one location, each of said recess means including a bottom portion disposed inwardly of an outwardly facing opening and through which opening the inner end portion of said armature member extends.

5. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station, a plurality of jack means each of which is associated with one of said needles and is operable between knit and nonknit conditions, and a plurality of actuator means disposed at the knitting station for effecting operation of said jack means between the knit and nonknit conditions, each of said actuator means including coil means energizable to provide a magnetic field, a frame member having a plurality of parallel interconnected leg sections including a first leg section extending through said coil means. a second leg section disposed on one side of said first leg section, and a third leg section disposed on a side of said first leg section opposite said side, an armature member movable under the influence of a magnetic field emanating from said coil means. and mounting means connected with said second and third leg sections for supporting said armature member for pivotal movement between a first position in which said armature member is ineffective to operate one of said jack means between the knit and nonknit conditions and a second position in which said armature member is effective to operate one of said jack means between the knit and nonknit conditions, said mounting means for each of said actuator means including a first recess means connected with said second leg section for engaging an inner end portion of said armature member at one location and a second recess means connected with said third leg section for engaging the inner end portion of said armature member at another location spaced from the one location. each of said recess means including a bottom portion disposed inwardly of an outwardly facing opening and through which opening the inner end portion of said armature member extends, each of said actuator means further including spring means for opposing movement of said armature member between the first and second positions and for pressing the inner end portion of said armature member against the bottom portions of said first and second recess means.

6. A knitting machine as set forth in claim 5 wherein said spring means includes a longitudinally extending spring member connected with said second and third leg sections at its outer end portions, said spring member having a portion disposed betweeen the outer end portions connected with said armature member.

7. A knitting machine as set forth in claim 5 wherein apexes formed by the intersection of side surfaces of said armature member are disposed in abutting engagement with the bottom portions of said first and second recess means when said armature member is in one of said first and second positions.

8. A knitting machine as set forth in claim 7 wherein one of the side surfaces of said armature member is disposed in abutting engagement with the bottom portion of at least one of said recess means when said armature member is in another one of said first and second positions.

9. A knitting machine as set forth in claim 5 wherein said armature member of each of said actuator means includes an inner end portion disposed in engagement with said mounting means and formed of a first metal and an outer end portion disposed adjacent to said jack means and formed of a second metal which is harder than said first metal. said outer end portion of said armature member including cam surface means formed of said second metal for engaging said jack means.

10. An actuator assembly for effecting movement of a knitting machine jack between knit and nonknit positions, said actuator assembly comprising armature means movable between a first position in which said armature means is ineffective to move the jack and a second position in which said armature means is effective to move the jack between the knit and nonknit positions, coil means for moving said armature means between the first and second positions u'pon energization of said coil means, said coil means being energizable to attract said armature means with a magnetic force which increases at an increasing rate as said armature means moves between the first and second positions. first spring means for providing a first biasing force opposing movement of said armature means between the first and second positions under the influence of the magnetic force. and second spring means for providing a second biasing force opposing movement of said armature means between the first and second positions after movement of said armature means against the first biasing force, said first and second spring means cooperating during movement of said armature means to provide a total biasing force which increases at a first rate during an initial portion of the movement of said armature means between the first and second positions and which increases at a second rate which is greater than the first rate during a final portion of the move ment of said armature means between the first and second positions.

H. An actuator assembly as set forth in claim it) further including a frame member having a plurality of interconnected leg sections including a first leg section extending through said coil. means. a second leg section disposed on one side of said first leg section. and a third leg section disposed on a side of said first leg section opposite said one side. and mounting means connected with said second and third leg sections for supporting said armature means for pivotal movement between the first and second positions.

12. An actuator assembly as set forth in claim I] wherein said first spring means includes a longitudi nally extending spring member connected to said second and third leg sections and said armature means in termediate the connections to said second and third leg means.

13. An actuator assembly as set forth in claim 10 wherein said armature means includes an armature member having an outer end portion for engaging the jack and an inner end portion disposed adjacent to said coil means. said actuator assembly further including mounting means for supporting said armature member for pivotal movement relative to said coil means, said mounting means including recess means for receiving a portion of said armature member, said recess means having an opening and bottom portion facing toward the outer end portion of said armature member, said armature member having a portion extending through said opening into engagement with said bottom portion of said recess. said opening having an area which is greater than the cross sectional area of any portion of said armature member disposed within said recess in a plane parallel to said opening to enable said armature member to move freely through said opening.

14. An actuator assembly as set forth in claim 13 wherein said first spring means presses said actuator member against the bottom portion of said recess means.

15. An actuator assembly as set forth in claim 14 wherein said inner end portion of said armature member is formed of a first metal and said outer end portion of said armature member is formed of a second metal which is harder than said first metal, said outer end portion of said armature member including cam surface means formed of said second metal for engaging the jack to move it between the knit and nonknit positions.

16. A knitting machine comprising a base, a plurality of knitting needles, a plurality of longitudinally extending jacks each of which is operatively connected with an associated one of said needles and has a butt which is movable between knit and non knit positions, said jacks being arranged in a plurality of groups of equal number with the ubtts of the jacks in each group being arranged in echelon formation which is the same for each of the groups. carrier means connected with said base and said jacks for sequentially moving the knitting needles and associated jacks through a plurality of knitting stations, and a plurality of interchangeable actuator modules each of which is connected with said base at one of said knitting stations, each of said modules including a first longitudinally extending support element. a second longitudinally extending support element spaced apart from said first longitudinally extending support element. and a longitudinally extending cover member connected with and extending at least partially across the space between said first and second support elements. said cover member including means which at least partially defines a longitudinally extending array of openings each of which has a stop surface extending transversely to said first and second support elements. each of said modules further including an array of electromagnetic actuators disposed in a single column between said first and second longitudinally extending support elements with the number of electromagnetic actuators in the column being equal to the number of jacks in a group. each of said electromagnetic actuators being associated with a different one of the openings in said cover member. each of said electromagnetic actuators including coil means having a central axis extending transversely to the longitudinal axes of said first and second support elements and of said jacks for providing a magnetic field upon energization of said coil means, frame means extending between said first and second support elements for supporting said coil means, said frame means having a first side portion connected with said first support element, a second side portion connected with said second sup port element and a central portion disposed intermediate said first and second side portions and connected with said coil means, an armature member pivotally connected with said frame means and extending through one of said openings in said cover member, and means for supporting said armature member for pivotal movement between a first position in which said armature member is disposed in abutting engagement with said stop surface of the associated one of said openings and extends into the path of movement of at least some of said jack butts and a second position in which said armature member is spaced apart from said stop surface.

17. A knitting machine as set forth in claim 16 wherein each of said modules further includes longitudinally extending register surface means for engaging the frame means of each of said electromagnetic actuators to position them along the central axes of said coil means with the outer end portions of said armature members in predetermined locations relative to said jacks, said register surface means being connected with said support elements and having a longitudinal axis extending substantially parallel to the longitudinal axes of said jacks.

18. A knitting machine as set forth in claim 17 wherein said first and second support elements include second register surface means for engaging the frame means of each of said electromagnetic actuators to position them along axes extending transversely to the central axes of said coil means with the central axes of said coil means disposed in a flat plane defined by the central axes of a pair of said coil means.

19. A knitting machine as set forth in claim 16 further including first register surface means at each of the knitting stations for positioning said modules relative to said jacks along a first axis. and second register surface means at each of the knitting stations for positioning said modules relative to said jacks along a second axis extending perpendicular to said first axis.

20. A knitting machine as set forth in claim 16 wherein said means for supporting said armature member includes means for supporting said armature member for pivotal movement about an axis extending transversely to the central axis of said coil means and to the longitudinal axes of said jacks.

21. An actuator assembly for effecting movement of a knitting machine jack between knit and nonknit positions. said actuator assembly comprising an armature member pivotal between a first position in which said armature member is ineffective to move the jack and a second position in which an outer end portion of said armature member is effective to move the jack between the knit and nonknit positions, coil means for moving said armature member between the first and second positions, first mounting means connected with said coil means for engaging an inner end portion of said armature member at one location to at least partially support said armature member for pivotal movement between the first and second positions. second mounting means connected with said coil means and spaced apart from said first mounting means for engaging the inner end portion of said armature member at another location spaced from said one location to at least partially support said armature member for pivotal movement between the first and second positions, said first and second mounting means each including recess means for receiving the inner end portion of said armature member, each of said recess means having a bottom portion and an opening facing toward the outer end portion of said armature and through which opening the inner end portion of said armature member extends into abutting engagement with the bottom portion of said recess means. and spring means for pressing the inner end portion of said armature member against said bottom portions of said recess means to retain said armature member against outward movement away from said bottom portions of said recess means.

22. An actuator assembly as set forth in claim 21 wherein said spring means is connected with said arma ture member and is effective to oppose movement of said armature member between the first and second positions.

23. An actuator assembly as set forth in claim 2] wherein said armature member has major and minor surfaces which intersect at said one location. said corner portion having an apex which is disposed in abutting engagement with said bottom portion of one of said recess means when said armature member is in said first position.

24. An actuator assembly as set forth in claim 23 wherein said minor surface of said actuator member is disposed in abutting engagement with said bottom por tion of said one recess means when said armature member is in said second position.

25. An actuator assembly as set forth in claim 21 wherein a cam surface means is formed on said outer end portion of said armature member to press against the jack and move it between the knit and nonknit positions. said cam surface means having a longitudinal axis extending at an angle relative to an axis about which said armature member pivots between said first and second positions such that engagement of said cam surface means with the jack tends to rotate the actuator member about an axis disposed intermediate said first and second mounting means.

26. An actuator assembly as set forth in claim 21 wherein said bottom portions of said recess means are at least partially defined by surfaces having areas which are equal to or less than the areas of the associated one of said openings.

27. An actuator assembly as set forth in claim 26 wherein said bottom surface of said recess means extend parallel to each other and an axis about which said armature member pivots upon movement of said armature member between the first and second positions.

28. An actuator assembly as set forth in claim 2] further including a frame member having a plurality of interconnected leg sections including a first leg section extending through said coil means. a second leg section disposed on one side of said first leg section. and a third leg section disposed on a side of said first leg section opposite said one side. said first mounting means being connected with said second leg section. said second mounting means being connected with said third leg section.

29. An actuator assembly as set forth in claim 28 wherein said spring means includes a beam spring member which extends between said second and third leg sections.

30. A knitting machine comprising a base. a plurality of knitting needles. a plurality of longitudinally extendingjacks each of which is connected with an associated one of said needles and has a butt which is movable between knit and nonknit positions. said jacks being arranged in a plurality of groups of equal number with the butts of the jacks in each group being arranged in echelon formation which is the same for each of the groups. carrier means connected with said base and said jacks for sequentially moving the knitting needles and associated jacks through a pluraltiy of knitting stations. and a plurality of interchangeable actuator modules each of which is connected with said base at one of said knitting stations, each of said modules including an array of electromagnetic actuators disposed in a single column with the number of electromagnetic actuators in the column being equal to the number of jacks in a group, each of said electromagnetic actuators including coil means having a central axis extending transversely to the longitudinal axes of said jacks for providing a magnetic field upon energization of said coil means. frame means for supporting said coil means. an armature member connected with said frame means. means for supporting said armature member for pivotal movement about an axis extending transversely to the central axis of said coil means and to the longitudinal axes of said jacks. and connector means for releasably conneacting each of said modules with said base. the magnetic field emanating from said coil means of each of said electromagnetic actuators being effective upon energization thereof to attract said armature member toward said coil means with a magnetic force which increases at an increasing rate as said armature member moves toward said coil means. each of said electromagnetic actuators further including first spring means for providing a first biasing force opposing movement of said armature member under the influence of the magnetic force emanating from said coil means. can second spring means for providing a second biasing force which is effective to oppose movement of said armature member after said armature member has moved against the influence of said first biasing force. said first and second spring means cooperating during movement of said armature member to provide a total biasing force which increases at a first rate during a initial portion of the movement of said armature member and which increases at a second rate which is greater than the first rate during a final portion of the movement of said armature member.

3!. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station. a plurality of jack means each of which is associated with one of said needles and is operable between knit and nonknit conditions. and a plurality of actuator means disposed at the knitting station for effecting operation of said 'jack means between the knit and nonknit conditions. each of said ac tuator means including coil means energizable to provide a magnetic field. a frame member having a plurality of parallel interconnected leg sections including a first leg section extending through said coil means. a second leg section disposed on one side of said first leg section. and a third leg section disposed on a side of said first leg section opposite said one side, an armature member movable under the influence of a magnetic field emanating from said coil means. said armature member being pivotal between a first position in which said armature member is ineffective to operate one of said jack means between the knit and nonknit conditions and a second position in which said armature member is effective to operate one of said jack means between the knit and nonknit conditions. said armature membe including a first porition adjacent to said second leg section and a second portion disposed adjacent to said third leg section. first recess means connected with said second leg section for supporting said first portion of said armature member for pivotal movement, said first recess means including a first bottom portion disposed inwardly of a first outwardly facing opening. said first portion of said armature member extending through said first opening into abutting engagement with said first bottom portion, said first portion of said armature member being pivotal relative to said frame member at the location where said first portion of said armature member engages said first bottom portion of said first recess means, second recess means connected with said third leg section for supporting said second portion of said armature member for pivotal movement. said second recess means including a second bottom portion disposed inwardly of a second outwardly facing opening. said second portion of said armature member extending through said second opening into abutting engagement with said second bottom portion. said second portion of said armature member being pivotal relative to said frame member at the location where said second portion of said armature mem ber engages said second bottom portion of said second recess means.

32. A knitting machine as set forth in claim 31 wherein each of said actuator means further includes spring means for pressing said first portion of said armature member against said first bottom portion of said first recess means and for pressing said second portion of said armature member against said second bottom portion of said second recess means.

33. A knitting machine as set forth in claim 3] wherein said first portion of said armature member includes side surface areas which cooperate to define a first apex disposed in abutting engagement with said first bottom portion of said first recess means when said armature member is in one of said first and second positions. said second portion of said armature member including side surface areas which cooperate to define a second apex disposed in abutting engagement with said second bottom portion of said second recess means when said armature member is in one of said first and second position. said armature member being pivotal about said first and second apexes during at least a portion of the movement of said armature member between said first and second positions.

34. A knitting machine as set forth in claim 33 wherein one of the side surface areas of said first portion of said armature member is disposed in abutting engagement with said first bottom portion of said first recess means when said armature member is in another one of said first and second positions. one of said side surface areas of said second portion of said armature member being disposed in abutting engagement with said second bottom portion of said second recess means when said armature member is in said other one of said first and second positions.

35. A knitting machine as set forth in claim 33 wherein each.of said actuator means further includes spring means for pressing said first and second apexes against said first and second bottom portions when said armature member is in said one of said first and second positions.

36. A knitting machine as set forth in claim 31 further including one spring member biasing said armature member toward one of said first and second positions and for pressing said first and second portions of said armature member against said bottom portions of said recess means.

37. An actuator assembly for effecting movement of a knitting machine jack between knit and nonknit positions. said actuator assembly comprising a base member. an armature member connected with said base member for pivotal movement relative to said base member between a first position in which said armature member is ineffective to move the jack and a second position in whcih an outer end portion of said armature member is effective to move the jack between the knit and nonknit positions, coil means for providing a magnetic field to effect movement of said armature member between the first and second positions upon energization of said coil means. mounting means connected with said base member for engaging an inner end portion of said armature member to at least partially support said armature member for pivotal movement between the first and second positions. said mounting means including recess means for receiving the inner end portion of said armature member, said recess means having a bottom portion and an opening through which the inner end portion of said armature member extends into abutting engagement with the bottom portion of said recess means, and spring means for pressing the inner end portion of said armature member against said bottom portion of said recess means to retain said armature member against outward movement away form said bottom portion of said recess means and for biasing said armature member toward one of said first and second positions.

38. An actuator assembly as set forth in claim 37 wherein said spring means includes a beam spring connected with said base member and said armature member.

39. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station. a plurality of jacts each of which is operatively connected with an associated one of the needles and has a butt which is movable between knit and nonknit position. said jack butts being movable along a circular path through the knitting station by said needle carrier. and a plurality of actuator means at the knitting station for effecting movement of the jack butts between the knit and nonknit positions. each of said actuator means including a coil means for pro- 23 viding a magnetic field upon energization of said coil means. a stationary frame member magnetizable by said coil means upon energization of said coil means. an armature member movable relative to said frame member between a first position and a second position under the influence of a magnetic field emanating from said coil means and frame member. said armature member including an inner portion disposed adjacent to said coil means formed of a first material having relatively low residual magnetism upon de-energization of said coil means and an outer end portion disposed adjacent to said jack butts and formed of a second material which is harder than said first material. said outer end portion including can surface means formed of said second material for engaging said jack butts. said cam surface means being movable by said armature member from a position offset from the path of movement of said jack butts through the knitting station to a position disposed in the path of movement of said jack butts through the knitting station upon movement of said armature member from the first position to the second position. mounting means connected with said frame member for supporting said armature member for pivotal movement between the first and second positions about a pivot axis extending transversely to a central axis of said coil means. and stop means for engaging said armature member at a location disposed intermediate said cam surface means and said pivot axis upon movement of said armature member from the first position to the second position, said stop means includes a member formed of a nonmagnetizable material to prevent engagement of said armature with said frame member upon movement of said armature with said frame member upon movement of said armature from said first position to said second position upon energi' zation of said coil means.

40. A knitting machine as. set forth in claim 39 wherein said frame member has a plurality of parallel leg sections. a first one of said leg sections extending through said coil means. a second one of saidleg sections being disposed on one side of said first leg section. and a third one of said leg sections being on a side of said first leg section opposite from said one side. said mounting means including first mounting means connected with said second leg section and engaging a first portion of said armature member and second mounting means connected with said third leg section and engaging a second portion of said armature member.

UNITED STAIES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,896,639 Dat d July 29, 1975 I v Christiansen et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In claim 5, line 15 after "said" and before "side", insert --one--.

In claim 16, line 5 after "and" and before "positions", delete "non knit" and insert -nonknit-.

In claim. 16, line 7 after "the" and before "of" delete "ubtts and insert --butts--.

In claim 30, line 8, delete "lon formation" and insert -lonformation--. Q

In claim 30, line 38, delete "force" and insert field--, and

delete "can" and insert -and-.

V In claim 30, line 45 after "during", delete "a" and insert --an. Q

In claim 33, line 12, delete "position," and insert -positions,-.

In claim 37, line 8, delete "whcih" and insert --which--.

1' In claim 37, line 27, delete "form" and insert -from-.

In claim 39, line 3, delete "jacts" and insert -jacks--.

In claim 39, line 6, delete "position," and insert -positions,-,

In claim 39, line 25, delete "can" and insert -cam.

In claim 39, lines 44 and 45, after "armature" and before "from" delete "with said frame member upon movement of said armature".

Signed and Scaled this ninth Day Of Marc h1976 [SEAL] a Arrest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner oj'Parenrs and Trademarks

Claims

1. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station, a plurality of jack means each of which is associated with one of said needles and is operable between knit and nonknit conditions, and a plurality of actuator means disposed at the knitting station for effecting operation of said jack means between the knit and nonknit conditions, each of said actuator means including coil means energizable to provide a magnetic field, a frame member having a plurality of parallel interconnecteD leg sections including a first leg section extending through said coil means, a second leg section disposed on one side of said first leg section, and a third leg section disposed on a side of said first leg section opposite said one side, an armature member movable under the influence of a magnetic field emanating from said coil means, and mounting means connected with said second and third leg sections for supporting said armature member for pivotal movement between a first position in which said armature member is ineffective to operate one of said jack means between the knit and nonknit conditions and a second position in which said armature member is effective to operate one of said jack means between the knit and nonknit conditions, the magnetic field emanating from said coil means of each of said actuator means being effective upon energization thereof to attract said armature member with a magnetic force which increases at an increasing rate as said armature member moves between the first and second positions, each of said actuator means further including first spring means for providing a first biasing force opposing movement of said armature member between the first and second positions under the influence of the magnetic field emanating from said coil means, and second spring means for providing a second biasing force which is effective to oppose movement of said armature member after said armature member has moved part way between said first and second positions against the influence of said first biasing force, said first and second spring means cooperating during movement of said armature member to provide a total biasing force which increases at a first rate during an initial portion of the movement of said armature member between the first and second positions and which increases at a second rate which is greater than the first rate during a final portion of the movement of said armature member between the first and second positions.

3. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station, a plurality of jack means each of which is associated with one of said needles and is operable between knit and nonknit conditions, and a plurality of actuator means disposed at the knitting station for effecting operation of said jack means between the knit and nonknit conditions, each of said actuator means including coil means energizable to provide a magnetic field, a frame member having a plurality of parallel interconnected leg sections including a first leg section extending through said coil means, a second leg section disposed on one side of said first leg section, and a third leg section disposed on a side of said first leg section opposite said one side, an armature member movable under the influence of a magnetic field emanating from said coil means, mounting means connected with said second and third leg sections for supporting said armature member for pivotal movement between a first position in which said armature member is ineffective to operate one of said jack means between the knit and nonknit conditions and a second position in which said armature member is effective to operate one of said jack means between the knit and nonknit conditions, and spring means for providing a biasing force opposing movement of said armature member between the first and second positions, said spring means including a beam spring member extending transversely to said leg sections and having a central porition connected to said armature member, one end portion connected with said second leg sectIon, and another end portion connected with said third leg section.

5. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station, a plurality of jack means each of which is associated with one of said needles and is operable between knit and nonknit conditions, and a plurality of actuator means disposed at the knitting station for effecting operation of said jack means between the knit and nonknit conditions, each of said actuator means including coil means energizable to provide a magnetic field, a frame member having a plurality of parallel interconnected leg sections including a first leg section extending through said coil means, a second leg section disposed on one side of said first leg section, and a third leg section disposed on a side of said first leg section opposite said side, an armature member movable under the influence of a magnetic field emanating from said coil means, and mounting means connected with said second and third leg sections for supporting said armature member for pivotal movement between a first position in which said armature member is ineffective to operate one of said jack means between the knit and nonknit conditions and a second position in which said armature member is effective to operate one of said jack means between the knit and nonknit conditions, said mounting means for each of said actuator means including a first recess means connected with said second leg section for engaging an inner end portion of said armature member at one location and a second recess means connected with said third leg section for engaging the inner end portion of said armature member at another location spaced from the one location, each of said recess means including a bottom portion disposed inwardly of an outwardly facing opening and through which opening the inner end portion of said armature member extends, each of said actuator means further including spring means for opposing movement of said armature member between the first and second positions and for pressing the inner end portion of said armature member against the bottom portions of said first and second recess means.

9. A knitting machine as set forth in claim 5 wherein said armature member of each of said actuator means includes an inner end portion disposed in engagement with said mounting means and formed of a first metal and an outer end portion disposed adjacent to said jack means and formed of a second metal which is harder thaN said first metal, said outer end portion of said armature member including cam surface means formed of said second metal for engaging said jack means.

10. An actuator assembly for effecting movement of a knitting machine jack between knit and nonknit positions, said actuator assembly comprising armature means movable between a first position in which said armature means is ineffective to move the jack and a second position in which said armature means is effective to move the jack between the knit and nonknit positions, coil means for moving said armature means between the first and second positions upon energization of said coil means, said coil means being energizable to attract said armature means with a magnetic force which increases at an increasing rate as said armature means moves between the first and second positions, first spring means for providing a first biasing force opposing movement of said armature means between the first and second positions under the influence of the magnetic force, and second spring means for providing a second biasing force opposing movement of said armature means between the first and second positions after movement of said armature means against the first biasing force, said first and second spring means cooperating during movement of said armature means to provide a total biasing force which increases at a first rate during an initial portion of the movement of said armature means between the first and second positions and which increases at a second rate which is greater than the first rate during a final portion of the movement of said armature means between the first and second positions.

11. An actuator assembly as set forth in claim 10 further including a frame member having a plurality of interconnected leg sections including a first leg section extending through said coil, means, a second leg section disposed on one side of said first leg section, and a third leg section disposed on a side of said first leg section opposite said one side, and mounting means connected with said second and third leg sections for supporting said armature means for pivotal movement between the first and second positions.

12. An actuator assembly as set forth in claim 11 wherein said first spring means includes a longitudinally extending spring member connected to said second and third leg sections and said armature means intermediate the connections to said second and third leg means.

13. An actuator assembly as set forth in claim 10 wherein said armature means includes an armature member having an outer end portion for engaging the jack and an inner end portion disposed adjacent to said coil means, said actuator assembly further including mounting means for supporting said armature member for pivotal movement relative to said coil means, said mounting means including recess means for receiving a portion of said armature member, said recess means having an opening and bottom portion facing toward the outer end portion of said armature member, said armature member having a portion extending through said opening into engagement with said bottom portion of said recess, said opening having an area which is greater than the cross sectional area of any portion of said armature member disposed within said recess in a plane parallel to said opening to enable said armature member to move freely through said opening.

16. A knitting machine comprising a bAse, a plurality of knitting needles, a plurality of longitudinally extending jacks each of which is operatively connected with an associated one of said needles and has a butt which is movable between knit and non knit positions, said jacks being arranged in a plurality of groups of equal number with the ubtts of the jacks in each group being arranged in echelon formation which is the same for each of the groups, carrier means connected with said base and said jacks for sequentially moving the knitting needles and associated jacks through a plurality of knitting stations, and a plurality of interchangeable actuator modules each of which is connected with said base at one of said knitting stations, each of said modules including a first longitudinally extending support element, a second longitudinally extending support element spaced apart from said first longitudinally extending support element, and a longitudinally extending cover member connected with and extending at least partially across the space between said first and second support elements, said cover member including means which at least partially defines a longitudinally extending array of openings each of which has a stop surface extending transversely to said first and second support elements, each of said modules further including an array of electromagnetic actuators disposed in a single column between said first and second longitudinally extending support elements with the number of electromagnetic actuators in the column being equal to the number of jacks in a group, each of said electromagnetic actuators being associated with a different one of the openings in said cover member, each of said electromagnetic actuators including coil means having a central axis extending transversely to the longitudinal axes of said first and second support elements and of said jacks for providing a magnetic field upon energization of said coil means, frame means extending between said first and second support elements for supporting said coil means, said frame means having a first side portion connected with said first support element, a second side portion connected with said second support element and a central portion disposed intermediate said first and second side portions and connected with said coil means, an armature member pivotally connected with said frame means and extending through one of said openings in said cover member, and means for supporting said armature member for pivotal movement between a first position in which said armature member is disposed in abutting engagement with said stop surface of the associated one of said openings and extends into the path of movement of at least some of said jack butts and a second position in which said armature member is spaced apart from said stop surface.

19. A knitting machine as set forth in claim 16 further including first register surface means at each of the knitting stations for positioning said modules relative to said jacks along a first axis, and second register surface means at each of the knittiNg stations for positioning said modules relative to said jacks along a second axis extending perpendicular to said first axis.

21. An actuator assembly for effecting movement of a knitting machine jack between knit and nonknit positions, said actuator assembly comprising an armature member pivotal between a first position in which said armature member is ineffective to move the jack and a second position in which an outer end portion of said armature member is effective to move the jack between the knit and nonknit positions, coil means for moving said armature member between the first and second positions, first mounting means connected with said coil means for engaging an inner end portion of said armature member at one location to at least partially support said armature member for pivotal movement between the first and second positions, second mounting means connected with said coil means and spaced apart from said first mounting means for engaging the inner end portion of said armature member at another location spaced from said one location to at least partially support said armature member for pivotal movement between the first and second positions, said first and second mounting means each including recess means for receiving the inner end portion of said armature member, each of said recess means having a bottom portion and an opening facing toward the outer end portion of said armature and through which opening the inner end portion of said armature member extends into abutting engagement with the bottom portion of said recess means, and spring means for pressing the inner end portion of said armature member against said bottom portions of said recess means to retain said armature member against outward movement away from said bottom portions of said recess means.

22. An actuator assembly as set forth in claim 21 wherein said spring means is connected with said armature member and is effective to oppose movement of said armature member between the first and second positions.

23. An actuator assembly as set forth in claim 21 wherein said armature member has major and minor surfaces which intersect at said one location, said corner portion having an apex which is disposed in abutting engagement with said bottom portion of one of said recess means when said armature member is in said first position.

24. An actuator assembly as set forth in claim 23 wherein said minor surface of said actuator member is disposed in abutting engagement with said bottom portion of said one recess means when said armature member is in said second position.

25. An actuator assembly as set forth in claim 21 wherein a cam surface means is formed on said outer end portion of said armature member to press against the jack and move it between the knit and nonknit positions, said cam surface means having a longitudinal axis extending at an angle relative to an axis about which said armature member pivots between said first and second positions such that engagement of said cam surface means with the jack tends to rotate the actuator member about an axis disposed intermediate said first and second mounting means.

28. An actuator assembly as set forth in claim 21 further including a frame member having a plurality of interconnected leg sections including a first leg section extending through said coil means, a second leg section disposed on one side of said first leg section, and a third leg section disposed on a side of said first leg section opposite said one side, said first mounting means being connected with said second leg section, said second mounting means being connected with said third leg section.

30. A knitting machine comprising a base, a plurality of knitting needles, a plurality of longitudinally extending jacks each of which is connected with an associated one of said needles and has a butt which is movable between knit and nonknit positions, said jacks being arranged in a plurality of groups of equal number with the butts of the jacks in each group being arranged in echelon formation which is the same for each of the groups, carrier means connected with said base and said jacks for sequentially moving the knitting needles and associated jacks through a pluraltiy of knitting stations, and a plurality of interchangeable actuator modules each of which is connected with said base at one of said knitting stations, each of said modules including an array of electromagnetic actuators disposed in a single column with the number of electromagnetic actuators in the column being equal to the number of jacks in a group, each of said electromagnetic actuators including coil means having a central axis extending transversely to the longitudinal axes of said jacks for providing a magnetic field upon energization of said coil means, frame means for supporting said coil means, an armature member connected with said frame means, means for supporting said armature member for pivotal movement about an axis extending transversely to the central axis of said coil means and to the longitudinal axes of said jacks, and connector means for releasably conneacting each of said modules with said base, the magnetic field emanating from said coil means of each of said electromagnetic actuators being effective upon energization thereof to attract said armature member toward said coil means with a magnetic force which increases at an increasing rate as said armature member moves toward said coil means, each of said electromagnetic actuators further including first spring means for providing a first biasing force opposing movement of said armature member under the influence of the magnetic force emanating from said coil means, can second spring means for providing a second biasing force which is effective to oppose movement of said armature member after said armature member has moved against the influence of said first biasing force, said first and second spring means cooperating during movement of said armature member to provide a total biasing force which increases at a first rate during a initial portion of the movement of said armature member and which increases at a second rate which is greater than the first rate during a final portion of the movement of said armature member.

31. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station, a plurality of jack means each of which is associated with one of said needles and is operable between knit and nonknit conditions, and a plurality of actuator means disposed at the knitting station for effecting operation of said jack means between the knit and nonknit conditions, each of said actuator means including coil means energizable to provide a magnetic field, a frame member having a plurality of parallel interconnected leg sections including a first leg section extending through said coil means, a second leg section disposed on one side of said first leg section, and a third leg section disposed on a side of said first leg section opposite said one side, an armature member movable undeR the influence of a magnetic field emanating from said coil means, said armature member being pivotal between a first position in which said armature member is ineffective to operate one of said jack means between the knit and nonknit conditions and a second position in which said armature member is effective to operate one of said jack means between the knit and nonknit conditions, said armature membe including a first porition adjacent to said second leg section and a second portion disposed adjacent to said third leg section, first recess means connected with said second leg section for supporting said first portion of said armature member for pivotal movement, said first recess means including a first bottom portion disposed inwardly of a first outwardly facing opening, said first portion of said armature member extending through said first opening into abutting engagement with said first bottom portion, said first portion of said armature member being pivotal relative to said frame member at the location where said first portion of said armature member engages said first bottom portion of said first recess means, second recess means connected with said third leg section for supporting said second portion of said armature member for pivotal movement, said second recess means including a second bottom portion disposed inwardly of a second outwardly facing opening, said second portion of said armature member extending through said second opening into abutting engagement with said second bottom portion, said second portion of said armature member being pivotal relative to said frame member at the location where said second portion of said armature member engages said second bottom portion of said second recess means.

33. A knitting machine as set forth in claim 31 wherein said first portion of said armature member includes side surface areas which cooperate to define a first apex disposed in abutting engagement with said first bottom portion of said first recess means when said armature member is in one of said first and second positions, said second portion of said armature member including side surface areas which cooperate to define a second apex disposed in abutting engagement with said second bottom portion of said second recess means when said armature member is in one of said first and second position, said armature member being pivotal about said first and second apexes during at least a portion of the movement of said armature member between said first and second positions.

34. A knitting machine as set forth in claim 33 wherein one of the side surface areas of said first portion of said armature member is disposed in abutting engagement with said first bottom portion of said first recess means when said armature member is in another one of said first and second positions, one of said side surface areas of said second portion of said armature member being disposed in abutting engagement with said second bottom portion of said second recess means when said armature member is in said other one of said first and second positions.

35. A knitting machine as set forth in claim 33 wherein each of said actuator means further includes spring means for pressing said first and second apexes against said first and second bottom portions when said armature member is in said one of said first and second positions.

37. An actuatOr assembly for effecting movement of a knitting machine jack between knit and nonknit positions, said actuator assembly comprising a base member, an armature member connected with said base member for pivotal movement relative to said base member between a first position in which said armature member is ineffective to move the jack and a second position in whcih an outer end portion of said armature member is effective to move the jack between the knit and nonknit positions, coil means for providing a magnetic field to effect movement of said armature member between the first and second positions upon energization of said coil means, mounting means connected with said base member for engaging an inner end portion of said armature member to at least partially support said armature member for pivotal movement between the first and second positions, said mounting means including recess means for receiving the inner end portion of said armature member, said recess means having a bottom portion and an opening through which the inner end portion of said armature member extends into abutting engagement with the bottom portion of said recess means, and spring means for pressing the inner end portion of said armature member against said bottom portion of said recess means to retain said armature member against outward movement away form said bottom portion of said recess means and for biasing said armature member toward one of said first and second positions.

39. A knitting machine comprising needle carrier means for moving a plurality of knitting needles through a knitting station, a plurality of jacts each of which is operatively connected with an associated one of the needles and has a butt which is movable between knit and nonknit position, said jack butts being movable along a circular path through the knitting station by said needle carrier, and a plurality of actuator means at the knitting station for effecting movement of the jack butts between the knit and nonknit positions, each of said actuator means including a coil means for providing a magnetic field upon energization of said coil means, a stationary frame member magnetizable by said coil means upon energization of said coil means, an armature member movable relative to said frame member between a first position and a second position under the influence of a magnetic field emanating from said coil means and frame member, said armature member including an inner portion disposed adjacent to said coil means formed of a first material having relatively low residual magnetism upon de-energization of said coil means and an outer end portion disposed adjacent to said jack butts and formed of a second material which is harder than said first material, said outer end portion including can surface means formed of said second material for engaging said jack butts, said cam surface means being movable by said armature member from a position offset from the path of movement of said jack butts through the knitting station to a position disposed in the path of movement of said jack butts through the knitting station upon movement of said armature member from the first position to the second position, mounting means connected with said frame member for supporting said armature member for pivotal movement between the first and second positions about a pivot axis extending transversely to a central axis of said coil means, and stop means for engaging said armature member at a location disposed intermediate said cam surface means and said pivot axis upon movement of said armature member from the first position to the second position, said stop means includes a member formed of a nonmagnetizable material to prevent engagement of said armature with said frame member upon movement of said armature with said frame member upon movement of said armature from said first positioN to said second position upon energization of said coil means.

40. A knitting machine as set forth in claim 39 wherein said frame member has a plurality of parallel leg sections, a first one of said leg sections extending through said coil means, a second one of said leg sections being disposed on one side of said first leg section, and a third one of said leg sections being on a side of said first leg section opposite from said one side, said mounting means including first mounting means connected with said second leg section and engaging a first portion of said armature member and second mounting means connected with said third leg section and engaging a second portion of said armature member.