US3018745A - Sewing machine feed mechanism - Google Patents

Description

1962 J. M. WASHBURN 3,018,745

SEWING MACHINE FEED MECHANISM Filed Nov. 16, 1959 5 Sheets-Sheet 1 IMUQTI/OWZ @FazzM-Wshburm y EWJLW W His-Atorneys Jan. 30, 1962 J. M. WASHBURN 3,018,745

SEWING MACHINE FEED MECHANISM Filed Nov. 16, 1959 5 Sheets-Sheet 2 7 2 6 /6 0 F 24 g2 17 I Inve nfior: JbhnMWashhurn Jan. 30, 1962 J. M. WASHBURN 3,018,745

SEWING MACHINE FEED MECHANISM Filed Nov. 16. 1959 5 Sheets-Sheet 5 Maw 9' I I. 3 'i':

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9/ 2 106 109 v 5 7 7 f r1 n .15- m0 95 21 54 1/ 17-- 89 I07 I; 6 13 105% 10/ E '1 13 v {as 83 p mu Inventor: cibll/n MWaskburn B3! M l M His Attorneys 3,018,745 SEWING MACHINE FEED MECHANISM John M. Washburn, West Hartford, Conn, assignor to The Morrow Machine Company, Hartford, Conn., a corporation of Connecticut Filed Nov. 16, 1959, Ser. No. 853,356 7 Claims. (61. 112-209) This invention relates to sewing machines, and more particularly to improvements in differential feed mechanism for sewing machines.

A primary object of the invention is to provide differential feed mechanism for a sewing machine in which the difierential feed may be varied by the operator without interrupting operation of the machine.

It is another object of the invention to provide differential feed mechanism for a sewing machine in which the length of feeding stroke of one element of the mechanism may be varied with precision over a substantial range while the machine is in operation.

In the attainment of these objects, the feeding mechanism includes a link oscillated about a pivotal axis by a driving member pivoted to the link a fixed distance from the pivotal axis. The feed dog is coupled to the link for adjustment radially of the pivotal axis to thereby vary the amplitude of movement imparted to the feed dog while maintaining the angle of oscillation of the link substantially constant. Preferably the adjustment is effected by shifting the pivotal axis of the link to move the link and its pivotal connection to the driving member relatively to the feed dog. The coupling between the link and feed dog is such that this adjusting movement can occur, if desired, while the feed mechanism is in operation.

Other objects and features of the invention will become apparent by reference to the following specification and to the drawings.

In the drawings:

FIG. 1 is an elevation view of the left end of a Merrow type sewing machine which embodies my invention;

FIG. 2 is an elevation view partly in section of the lower portion of the machine shown in FIG. 1 with certain overlying elements omitted;

FIG. 3 is a view similar to FIG. 2 but with still more parts omitted, broken away or in section;

FIG. 4 is a view similar to FIG. 3 but with certain elements appearing in a different position than as shown in FIG. 3;

FIG. 5 is a sectional plan detail view of parts shown in FIG. 4, together with manually operable adjusting means;

FIG. 6 is a view similar to FIG. 3 but showing elements ted States Patent U that are omitted in FIG. 3 and omitting certain elements that are shown in FIG. 3;

FIG. 7 is a vertical sectional view on line 7--7 of FIG. 6;

FIG. 8 is a vertical sectional view substantially on line 88 of FIG. 5;

FIG. 9 is a horizontal sectional view substantially on line 99 of FIG. 7;

FIG. 10 is a horizontal sectional detail view on line 10-10 of FIG. 5; and

FIG. 11 is a detail view partly in section of certain pivotal connections.

The sewing machine illustrated in the drawings is similar in many respects to the machine disclosed in United States Patent No. 2,769,416, granted November 6, 1956, upon an application of Bernard N. Pierce and differs from the machine shown in the Pierce patent by the inclusion of structure designed to achieve the above objectives. As in the machine shown in the Pierce patent, the machine of the present application includes a front feed dog F and a rear feed dog R which are respectively secured to front and rear feed bars or carriers 1 and 2. Carriers 1 and 2 ice are driven from a main drive shaft 3 journaled for rotation in the machine frame 4. Shaft 3 is driven in rotation by conventional mechanism not shown. Shaft 3 projects outwardly beyond one end of the machine frame and upon the projecting portion of the shaft a pair of eccentrics 5 and 6 are formed. The outer end of shaft 3 is threaded as at 7 to receive a nut 8 which holds blocks 9 (FIGS. 4 and 5) and 10 (FIGS. 6 and 9) upon eccentric shaft portion 6.

Feed dog carrier 1 is supported near its rearward end from frame 4 by a bracket 17 mounted upon a spacer 18 (see FIG. 7) which is in turn fixed to the end wall of machine frame 4. Spacer 18 is fixedly secured to machine frame 4 as by screws 19 (FIG. 8) while bracket 17 is bolted to spacer 18 as by bolts 20 (FIG. 5).

Spacer 18 accurately spaces vertical surface 21 of bracket 17 from the vertical end wall 22 (FIG. 8) of machine frame 4. As best seen in FIG. 8, feed dog carriers 1 and 2 slideably engage the bearing surfaces defined by walls 21 and 22 and are thus guided in movement in parallel vertical general planes.

Adjacent its rearward end, front feed dog carrier 1 is formed with a yoke 24 which slideably engages a block 25. Block 25 is supported upon machine frame 4 by a pin 26 which projects eccentrically from the end of a member 27 supported in the frame 4 as best seen in FIG. 5. Block 25 is supported for free pivotal movement upon pin 26. By rotation of member 27 relative to frame 4, it is believed apparent that the axis of pivotal movement of block 25 about pin 26 may be varied relative to machine frame 4. A set screw 29 is employed to lock pin 26 in selected positions of adjustments relative to frame 4. By virtue of the sliding engagement between front feed dog carrier 1 and block 25 and by virtue of the free pivotal movement of block 25 about the axis of pin 26, front feed dog carrier 1 is supported for angular movement about the axis of pin 26 and also for radial movement relative to the axis of pin 26.

Front carrier 1 is driven in angular oscillation about the axis of pin 26 by block 9 which is slideably received within a yoke 30 formed at the forward end of carrier 1. Radial reciprocatory movement of carrier 1 relative to the axis of pin 26 is derived from bushing 11 through structure to be described below. The net efiect of the snychronized angular and radial movement of carrier 1 relative to the axis of pin 26 is to drive front feed dog F in a motion such that any point on the front feed dog F moves in a substantially elliptical path when viewed as in FIG. 3. The major axis of this substantially elliptical path extends generally parallel to the upper surface of the work plate 16. Substantially all of the motion of front feed dog F perpendicular to the major axis of its elliptical path is derived from the angular oscillation of feed dog carrier 1 about the axis 26. Motion of front feed dog F having components extending parallel to major axis of the ellipse is substantially entirely derived from the eccentricity of the bushing 11 transmitted to the feed dog carrier by structure described below.

Near the rearward end of feed dog carrier 1, is a feed carrier block 31 is mounted for pivotal movement upon the carrier by a stud 32 having an enlarged head 33 countersunk within block 31 and secured to feed dog carrier 1 by a screw 34 (FIGS. 8 and ll). Referring now particularly to FIGS. 3 and 11, a dovetail slot is formed on the side of block 31 remote from the feed dog carrier by a stationary abutment 35 and an adjustable abutment or gib 37 secured to block 31 by screw 38 received within an elongated slot 38' in the gib. A slide 41 in the form of a link is slideably received within the dovetail slot of block 31 for longitudinal sliding movement within the slot in a direction which, as best seen in FIG. 3, extends radially of the axis of pivot 32.

Intermediate the ends of link 41, a bolt 43 having a head 44 seated in a counterbore in the sliding link passes through link 41 and is keyed against rotation relative to the link as by pin 45. A bushing 46 is secured upon bolt 43 as by nut 47, bushing 46 defining a first pivotal support upon the link. At the lower end of the link, pivotal support is mounted upon link 41 and includes a bolt 49, countersunk head 50, key 51, bushing 52 and nut 53.

A drive link 54 is journaled at one end upon bushing 46 for pivotal movement relative to link 41 about the axis of bolt 43. Drive link 54 is journaled at its other end upon eccentric bushing 11 on drive shaft 3 and, in order to provide clearance between feed dog carrier 1 and the link, link 54 is transversely offset as at 55. From FIG. 3, it is believed apparent that if the pivotal axis defined by the assembly including bolt 49 is held stationary, rotation of drive shaft 3 will cause drive link 54 to oscillate link 41 about the axis of bolt 49.

The pivotal assembly including bolt 49 is supported from the machine frame by structure including a rock shaft 60 journaled for rotation within a bearing 61 formed in bracket 17. An arm 63 having a hub 64 received upon shaft 60 is fixedly secured to the shaft as by set screw 65 (FIG. 3) and is journaled at its other end upon bushing 52 on the lower end of link 41. The opposite end of rock shaft 60 projects outwardly beyond bracket 17. A lever 67 is formed with an eye 70 to which peddle chain (not shown) may be attached and is secured at its opposite end by bolts 71 to a hub block 72 which is in turn clamped upon rock shaft 60 as by screw 73. A flattened portion 74 permits axial adjustment of hub 72 along shaft 60 to assure a snug fit of hubs 64 and 72 against the sides of bracket 17 at opposite ends of bearing 61. By movement of lever 67, arm 63 may be rotated about the pivotal axis of rock shaft 60 and to define end limits to such rotation, stop screws 74 and 75 are threadably received within hub 72 (FIG. 1) for respective engagement for stationary stop pins 76 and 77 fixedly mounted in bracket 17. Lever 67 is normally maintained in a position wherein stop screw 74 abuts stop pin 76 by a tension spring 78 connected at one end to an eye 79 in bracket 17 and at its opposite end to an eye 80 on lever 67. To frictionally maintain stop screws 74 and 75 at their adjusted settings, a channel 81 is cut through hub 72 to expose a portion of the stop screws in a manner as shown in FIG. 10. A leaf-spring 82 is clamped to the bottom of channel 81 as by screw 83 to resiliently bear against the sides of both stop screw 74 and stop screw 75 to resist unintentional turning movement of the screws.

The structure for supporting the rear feed dog carrier 2 is best shown in FIGS. 6, 7 and 9. Near its forward end, rear feed dog carrier 2 is formed with yoke 90 which slideably engages block mounted on eccentric 5. The rearward end of carrier 2 is supported upon a link 91 received within a channel 92 formed in spacer 18 as best seen in FIGS. 6 and 9. A pin 94 riveted as at 95 to the rearward end of carrier 2 pivotally couples the carrier to the upper end of link 91 while the lower end of the link is supported upon an eccentric pin 99 mounted at the outer end of a rotatable stud 97 supported within bracket 17. A groove 100 is formed upon stud 97 to receive the point of a set screw 101 threaded into bracket 17 whereby stud 97, and-hence said eccentric portion 99 may be adjustably positioned with respect to the fixed elements of the machine. The structure for supporting the lower end of link 91 is similar to and analogous in function to the structure which supports block 25 upon machine frame 4 as described in connection with front feed dog carrier 1.

A drive link 105 is journaled at one end upon eccentric 12 and is pivotally coupled at its other end directly to feed carrier 2 by a pivotal connection including a bushing 106 held upon carrier 2 as by a nut and bolt assembly 107l08. Because of the fact that bushing 106 must pass across the space occupied by drive link 54, an open- 4 ing 109 is cut through drive link 54 to provide clearance for bushing 106.

As is the case with feed dog carrier 1, rear feed dog carrier 2 is driven in a motion which finds any point upon rear feed dog carrier R being moved in a substantially elliptical path. Again the elliptical path in which the feed dog moves has its major axis extending substantially parallel to the adjacent surface of work plate 16, movement of the feed dog along the major axis of the substantially elliptical path being derived primarily from drive link while movement along the minor axis of the elliptical path is derived primarily from block 10. From the foregoing description, it will be noted that both feed dog carriers 1 and 2 have their rearward ends located with respect to the frame for pivotal movement about an axis whose location with respect to the frame is adjustable. In the case of feed dog 1, pin 26 is mounted eccentrically upon the end of the member which is rotatable within the frame. Rotation of member 27 within the frame raises or lowers pin 26, thereby raising or lowering the pivotal axis about which the rear portion of feed dog carrier 1 is constrained to move. Raising movement of the axis of pivot pin 26 tends to lower the location of the elliptical path of front feed dog F with respect to the frame, and particularly with respect to the surface of work plate 16. As the location of the elliptical path is lowered, that portion of the path during which front feed dog F projects above the upper surface of work plate 16 is decreased. Likewise, lowering movement of the axis of pin 26 elevates the path of front feed dog F and a greater portion of the elliptical path projects above the plane of work plate 16. This action has the effect of varying the effective length of the feeding stroke of front feed dog F. A similar action occurs with rear feed dog R upon adjustment of stud 97. By adjusting the relative length of the effective strokes of the front and rear feed dogs F and R, a differential feed is achieved in a manner familiar in the art;

It is often desirable to change the differential feed during different portions of a sewing operation upon the same piece of material. Adjustment of the differential feed by adjustment of pivot pins 26 and 99 is conventionally performed While the machine is not operating. In a sense, the adjustments provided by pins 26 and 99 may be said to be initial settings. Variation of the differential feed may be accomplished while the machine is in operation by operation of lever 67 to rotate rock shaft 60 with respect to the frame.

In FIGS. 3 and 4, arm 63 is shown in the respective positions it would assume at each of its rotative end limits. In FIG. 3, the axis of bolt 43 is located approximately midway between the axes of bolts 49 and pivot pin 32. In FIG. 4, at the opposite end limit of movement of arm 63, the axes of bolt 43 and pin 32 may be assumed to be in coincidence.

Referring now to FIG. 4, rotation of drive shaft 3 causes link 54 to drive link 41 in pivotal oscillation about the axis of bolt 49. The axis of the bolt 43 is thus driven along an arcuate path concentric to the axis of bolt 49 and this motion is of a fixed amplitude. Since the axis of pin 32 is coincident with the axis of bolt 43, the amplitude of motion imparted to pin 32 through block 31 is equal to the amplitude of'motion imparted to bolt 43 by the oscillation of drive link 54. This is because the radial distance between the axis of bolt 43 and the axis of bolt 49 is equal to the radial distance between the axis of pin 32 and bolt 49.

In FIG. 3 arm 63 has been located to a position which will be assumed to be at its opposite end limit. In this case, the radial distance between the axis of bolt 49 and the axis of pin 32 is approximately twice as great as the radial distance between the axis of bolts 49 and 43. Thus the circumferential motion of link 41 at the radius corresponding to the radial distance between the axis of bolt 49 and the axis of pin 32 is approximately twice as great asthe amplitude of motion of link 41 at the radius corresponding to the radial distance between the axis of bolts 49 and 43. Since the motion imparted to feed dog 41 by drive link 54 establishes for all practical purposes the length of the major axis of the elliptical path of feed dog carrier 1 when arm 63 is in the FIG. 3 position is approximately twice as great as the amplitude of the elliptical path when arm 63 is in the FIG. 4 position.

The arcuate amplitude of oscillation of link 41 about bolt 49 is substantially constant regardless of the position of arm 63 since the radial distance between bolts 49 and 43 is fixed and unvarying. Thus the amplitude of motion imparted to feed dog carrier 1 is directly proportional to the radial distance between the axis of bolt 49 and pin 32 divided by the radial distance between the axis of bolt 49 and the axis of bolt 43. This arrangement has the advantage that a given amount of movement of slide 41 by an angular adjustment of 'arm 63 results in a change in amplitude of the major axis of the elliptical path of front feed dog F which is directly proportional to the adjusting movement of link 41.

It is further believed to be apparent that the abovementioned exemplary limits of adjustment may be varied within practical ranges. For example, if adequate clearance is provided, link 41 may be moved to a position wherein the radial distance between pin 32 and bolt 49 was less than the distance between bolt 49 and bolt 43, thus making the magnification factor less than 1. Within limits, the magnification factor may also be increased above two. The particular arrangement also has the advantage in that it is not possible to inadvertently shift the adjustment to a position wherein the theoretical amplitude of feed dog carrier 1 would become infinite. Over the range of adjustment provided, the change in amplitude of movement of feed dog carrier 1 is directly proportional to the magnitude of the adjustment input, thus affording an extremely precise control over the adjustment. With this particular structural arrangement, it is immaterial whether the adjustment is made while the machine is stopped or made while the machine is running at full speed.

While I have described one exemplary embodiment of my invention it will be apparent to those skilled in the art that the foregoing embodiment may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting and the true scope of the invention is that defined in the following claims.

I claim:

1. In a sewing machine having a frame, first support means on said frame defining a first pivotal axis, a feed dog carrier supported at one end upon said first support means for angular and radial movement relative to said first axis, drive means for driving said carrier in angular oscillation about said first axis, second support means on said frame defining a second pivotal axis parallel to said first axis, a link supported at one end on said second support means for pivotal movement about said second axis, means connected between said drive means and said link for oscillating said link in pivotal movement of constant amplitude about said second axis in synchronism with the angular oscillations of said carrier about said first axis, coupling means connecting said link to said carrier for pivotal movement relative to said carrier about a third axis extending parallel to said first axis at a fixed location on said carrier and for sliding movement relative to said carrier radially of said third axis to oscillate said carrier radially of said first axis when said link is pivotally oscillated about said second axis with an amplitude of radial oscillation proportional to the distance between said second axis and said third axis, and means for shifting said second support means relative to said frame to vary the distance between said second axis and said third axis to thereby vary the amplitude of radial oscillation of said carrier.

2. In a sewing machine having a frame, first support 6 7 means on said frame defining a first pivotal axis, a feed dog carrier supported at one end upon said first support means for angular and radial movement relative to said first axis, drive means for driving said carrier in angular oscillation about said first axis, second support means on said carrier defining a second pivotal axis on said carrier parallel to said first axis, a link received by said second support means for angular and radial movement relative to said second axis, third support means on said frame defining a third pivotal axis parallel to said first axis, means coupling one end of said link to said third support means for pivotal movement about said third axis, means coupled to said drive means and said link for driving said link in pivotal oscillation of constant amplitude about said third axis in synchronism with the angular oscillation of said carrier about said first axis, said second support means transforming pivotal oscillation of said link about said third axis into radial oscillation of said carrier relative to said first axis, and means for shifting said third axis toward and away from said second axis to thereby vary the amplitude of radial oscillations of said carrier.

3. In a sewing machine having a frame, first support means on said frame defining a first pivotal axis, an. elongate feed dog carrier supported at one end upon said support means for angular and radial movement relative to said first axis, drive means for driving said carrier in angular oscillation about said first axis, a block mounted upon said carrier for pivotal movement about a second axis parallel to said first axis, an elongate link slideably received within said block for longitudinal sliding movement relative to said block radially of said second axis, second support means upon said frame defining a third pivotal axis parallel to said first axis, means coupling one end of said link to said second support means for pivotal movement about said third axis in an are having a substantial component longitudinally of said carrier, means coupled to said drive means and said link for driving said link in pivotal oscillation of constant amplitude about said third axis in synchronism with the angular oscillation of said carrier about said first axis, and means for shifting said second sup ort means toward and away from said block to slide said elongate link longitudinally within said block to thereby varv the radial distance between said third axis and said second axis.

4. In a sewing machine having a frame, first support means on said frame defining a first pivotal axis, an elongate feed dog carrier supported adjacent one end upon said first support means for angular and radial movement relative to said first axis, drive means for driving said carrier in angular oscillation about said first axis, a block mounted upon said carrier for pivotal movement about a second axis parallel to said first axis, means on said block defining a link receiving slot extending across said block in a direction radially of said second axis, an elongate link received within said slot for longitudinal sliding movement, a first pivot adjacent one end of said elongate link and a second pivot on said elongate link intermediate the ends thereof, said first and said second pivots being parallel to each other and said first pivotal axis, second support means on said frame spaced transversely of said carrier from said block and connected to said first pivot to couple said elongate link to said frame, drive link means connected to said second pivot and to said drive means for oscillating said elongate link in pivotal movement of constant amplitude about said first pivot in synchronism with the angular oscillation of said carrier about said first axis, that portion of said elongate link received within said slot being driven in an arcuate path about said first pivot having a substantial component of motion longitudinally of said feed dog carrier whereby pivotal movement of said link about said first axis drives said carrier in radial movement relative to said first axis, and means for shifting said second support means relative to said frame to vary the radial distance between said first pivot and second axis to thereby vary the amplitude of radial movement of said carrier while maintaining a constant amplitude of pivotal movement of said elongate link about said first pivot.

5. In a sewing machine having a frame, first support means on said frame defining a first pivotal axis, a feed dog carrier supported adjacent one end upon said first support means for angular and radial movement relative to said first axis, a drive shaft journaled for rotation within said frame, a pair of eccentrics on said drive shaft, means adjacent the other end of said carrier coupling said carrier to one of said eccentrics to oscillate said carrier in angular movement about said first axis, upon rotation of said drive shaft, second support means on said carrier defining a second pivotal axis fixed with respect to said carrier and extending parallel to said first axis, a link received by said second support means for angular and radial movement relative to said second axis, third support means on said frame defining a third pivotal axis parallel to said first axis, means coupling one end of said link to said third support means for pivotal movement about said third axis, a drive link coupled at one end to said link for pivotal movement relative to said link about a fourth axis located intermediate the ends of said link, means coupling the other end of said drive link to the other of said eccentrics to oscillate s aid link in pivotal movement about said third axis upon rotation of said shaft, and means for shifting said third support means relative to said frame to vary the distance beween said second axis and said third axis.

6. In a sewing machine having a frame, a feed mechanism comprising a feed dog carrier, means supporting said carrier on said frame for angular and radial movement relative to a carrier axis, a driving link, a pivotal support for said link, a driving member pivotally connected to said link at a point spaced from said pivotal support for oscillating said link about the pivotal axis of said pivotal support, means coupling said carrier to said link for imparting movement to said carrier radially of said carrier axis upon angular oscillation of said link about said pivotal axis and permitting movement of said link relative to said carrier in a direction radially of said pivotal axis, and means for shifting said pivotal support to adjust the distance between said coupling and said pivotal support to vary the amplitude of radial movement imparted to said carrier by oscillation of said link without changing the amplitude of angular oscillation of said link.

7. Sewing machine feed mechanism including in com bination, a rotary shaft, a pair of eccentrics carried upon said shaft, a feed dog carrier supported for oscillatory and reciprocatory movement and embracing one of said eccentrics, a block having pivotal connection with said carrier, said block being formed with a guideway, a lever slideably mounted in said guideway, said lever having thereon a first and second pivotal stud defining axes spaced a fixed distance from each other, a link having one end embracing the other of said eccentrics and its other end connected to said lever at one of said pivotal studs thereon for oscillating said lever about the other pivotal stud to impart reciprocatory movement to said carrier, and means coupled to the other of said pivotal studs for moving said lever to change the distance between one of said pivotal studs on said lever and the pivotal connection between said carrier and said block, thereby to vary the amplitude of reciprocatory movement imparted to said carrier.

References Cited in the file of this patent UNITED STATES PATENTS 1,069,363 Weis Aug. 5, 1913 1,856,360 Thompson May 3, 1932 2,009,747 Sauer July 30, 1935 2,341,448 Knaus Feb. 8, 1944 2,546,939 Breul Mar. 27, 1951 2,771,848 Knaul et al Nov. 27. 1956

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