US2681021A - Thread shifting mechanism for sewing machines - Google Patents

Description

n 15, 1 v H. v. KINDSETH Er AL ,0

THREAD SHIFTING MECHANISM FOR SEWING MACHINES 4 ShaetsvSheet 1 Original Filed Dec. 28, 1951 III INVENTORS HAPOAO M AVA/0.567 BY 644F040 K. Fax

n 1 1954 H. v. KINDSETH ErAI. 2,681,021

THREAD SHIFTING MECHANISM FOR SEWING MACHINE S Original Filed Dec. 28, 1951 4 Sheets-*Sheet 2 V7 3 2 ,7 i l /3 iPZZii lllll INVENTORS f/AFOLD V. Al/VOJfT/l HAROLO FOX June 15, 1954 H. v. KINDSETH ETAL 2,681,021

THREAD SHIFTING MECHANISM FOR SEWING MACHINES Original Fil ed Dec. 28, 1951 4 Sheets-Sheet 3 Il j &

' INVENTORS S 1 HAFflAD M/W/VOJETH K. FOX 70 I I BY HAFOAO June 1954 H. v. KINDSETH EI'AL 2,681,021

THREAD SHIFTING MECHANISM FOR SEWING MACHINES Original Filed Dec. 28, 1951 4 Sheets-Sheet 4 76 I 4 \w 7? 0% Wm M ATTOF/VfYS Patented June 15, 195 4 THREAD SHIFTING MECHANISM FOR SEWING MACHINES Harold V. Kindseth and Harold K. Fox, Minneapolis, Minn, assignors to Bemis Bro. Bag 00., Minneapolis, Minn, a corporation of Missouri Driginal application December 28, 1951, Serial Divided and this application April 18, 1952, Serial No. 233,004

4 Claims. 1

Our invention relates generally to power-driven sewing machines and, more specifically, to improvements in machines for stitching articles successively fed in spaced relation.

More particularly, the present invention is a division of our co-pending application filed December 28, 1951, Serial No. 253,826, and entitled Sewing Machine Actuator.

An important object of our invention is the provision of an attachment for power driven sewing machines having stitching mechanism and thread cutting means, said attachment including a thread engaging head and fluid pressure operated means for moving the head into engage ment with the stitched thread to carry the thread into position to be severed by the thread-cutting means.

Another object of our invention is the provision of an attachment for sewing machines as set forth having a control valve for the fluid pressure operated means and novel echanism associated with the means for driving the stitching means and thread cutting means for operating said control valve.

The above and other highly important objects and advantages of our invention will become apparent from the following detailed specification, appended claims and attached drawings.

Referring to the drawings which illustrate the invention and in which like characters indicate like parts throughout the several views:

Fig. 1 is a fragmentary view in side elevation, some parts broken away and some parts shown in section, of a power driven sewing machine and controls therefor built in accordance with the invention;

Fig. 2 is an enlarged fragmentary view partly in plan and partly in horizontal section taken substantially on the line 2-2 of Fig. 1;

Fig. 3, sheet 3, is a view corresponding to a portion of Fig. 2 but showing a different position of some of the parts;

Fig. 4 is a View partly in plan and partly in section taken substantially on the line l-t of Fig. 2, some parts being broken away;

Fig. 5, sheet 4, is a view partly in section and partly in side elevation taken substantially on the line 5-5 of Fig. 2;

Fig. 6 is a diagrammatic section of a valve of our invention;

Fig. 7 is an enlarged fragmentary detail, some parts being broken away and some parts shown in section, as seen from the line 'L-l of Fig. 2;

Fig. 8 is a view partly in plan and partly in section of a stitching thread carrier incorporated in the machine of our invention; and

Fig. 9, sheet 2, is a longitudinal sectional view of a portion of the control means of our invention.

In the drawings, a power driven sewing machine is shown as comprising a base 2 and a sewing head 3. The head 3 supports a needle 4 by means of a conventional rsciprocatory needle bar 5 and a presser foot 5 rigidly secured to the end of a reciprocating rod or shaft 'l. The sewing and feeding mechanism of the machine is conventional in nature and is shown in the drawings more or less diagrammatically. With reference particularly to Figs. 1-3 inclusive, it will be seen that the needle bar 5 and feeding mechanism are driven from a drive shaft 8, the needle bar 5 being operatively connected thereto by an eccentric operated pitman rod 9 a lever H1 pivotally mounted to the machine 6, as indicated at IE, and connected at one end to the pitman rod 9 and at its other end suitably connected to the opposite end of the needle bar 5. The feeding mechanism comprises an eccentric l 2 on the shaft 8 and a pitman arm 1 3-driven by the eccentric l2 and connected at its free end to a crank arm i4 fast on a rock shaft lb. The rock shaft i5 is suitably journaled in. the base 2 and has rigidly secured thereto a crank arm it which drives a pair of serrated feed dogs H and 53 through a rigid link 59. The feed dogs H and i8 extend laterally outwardly through apertures 2?! in a base plate 2| mounted on the base 2 by screws or the like 22, see Fig. 5.

The frame I of the sewing machine is rigidly secured to a mounting bracket 23 which is supported from a main supporting frame 24 by laterally extending arms 25, one of which is shown, see Fig. 1. With further reference to Fig. 1, it will be seen that a drive motor 26 is rigidly mounted on the upper end of the bracket 23 and drives the sewing and feeding mechanism through a V-belt 21' running over a V-pulley 28 on the drive shaft of the motor 25 and a similar pulley 29 mounted fast on the outer end of the drive shaft 8. The pulley 28 is provided with a clutch mechanism 30 which is controlled by a clutch lever 31 to operatively couple the pulley 28 to the motor 25. The clutch lever 3-! is pivotally secured intermediate its ends to a rigid arm 32 depending from the base of the motor 26. At its free end, the clutch lever 3| is secured by a coupling 33 to a plunger 34 operated by a solenoid, not shown but contained within a housing 35 secured to the base of the motor 26 and supported by the upper end of the bracket 23. The lever 3| is further provided with a spring 35 which biases the clutch 35 toward its inoperative position, shown by dotted lines in Fig. l, and an adjustable stop element 37. The stop element 3! is in the nature of a machine screw or the like having screw-threaded engagement in a laterally outwardly projecting arm 38 integrally formed with the lever 3|. The clutch and operating linkage therefor do not in themselves constitute the invention and further detailed description thereof is, therefore, deemed unnecessary.

The clutch operating solenoid contained in the housing 35 is controlled by a switch contained in a switch housing 39 and provided with an operating button 49. The switch housing 39 is rigidly secured to one end portion of a platelike bracket 4| that is anchored to the sewing head 3 by suitable means, not shown. The switch may be assumed to be of the momentary contact type in which the button 40 thereof is yieldingly biased toward a normal switch-open position. The switch within the housing 39 and the solenoid within the housing 35 are interposed in an electrical circuit including the motor 25 and a source of electrical potential, not shown. The above-mentioned electrical circuit and parts heretofore described are fully disclosed in our pending United States patent application, Serial No. 204,526, filed January 5, 1951, now Patent No. 2,630,086, dated March 3, 1953.

A switch button extension rod 42 is axially slidable in a bearing sleeve 33 in axial alignment with the button 45 and rigidly anchored to the switch housing 39 by means of a tubular mounting member 44. The extension rod 52 is provided with an axially extended internal recess 45 in which is slidably mounted a rod or shaft 36 having at its outer end a diametrically enlarged head or cap 11. A pin 48 extends radially outwardly of the rod 46, the outer end thereof being contained within an axially extended slot 49 in the outer end portion of the extension rod 42 whereby to provide limited axial movement of the shaft 56 relative to the extension rod 42. A coil compression spring 50 is interposed between the against bias of the spring 50, said overtravel being limited by the length of the slot 49.

The base plate 2| is provided with a slot or channel which extends longitudinally of the path of travel of bags being fed to the machine, see Figs. 5 and '7. In the drawings, filled bags to be stitched closed are indicated at A. The presser foot 6 is also provided with a slot 52 extending longitudinally of the bags A and in register with the slot 5| in the base plate 2|. A control member in the nature of a laterally movable control finger 53 extends in a direction parallel to the slots 5| and 52 in the base plate and presser foot respectively and is movable through the slot 52 laterally toward and away from a normal position wherein one longitudinal edge portion in contained within the slot 5| of the base plate 2| where it will intercept and be moved by the upper ends of the bags A when said upper ends are moved between the base plate and presser foot. Means for mounting the control finger 53 comprises a rigid link 54 that extends generally longitudinally of the control finger 53 and has one end pivotally secured to the bracket or mounting plate 4 as indicated at 55. At its opposite end, the link 54 is pivotally secured to a laterally projected lug or ear 53 integrally formed with the control finger 53 intermediate the ends thereof, see Figs. 2 and 3. It will also be seen, with reference to Figs. 2 and 3, that the forward end 5? of the control finger 53 and the corresponding end 58 of the presser foot 5 curve laterally outwardly to provide easy entrance therebetween and the base plate 2| of the upper ends'of the bags A as they approach the stitching mechanism. As will hereinafter be described, the upper ends of the bags A exert a camming action on the forward end of the control finger 53 to move the same laterally outwardly of the slot 5| in the base plate 2 l.

At its opposite or rear end, the control finger 53 is provided with a rearwardly projecting boss 59 in which is screw-threaded a lock nut-equipped stop screw 55 which is adapted to engage an abutment in the nature of an ear 5| integrally formed with the mounting bracket or plate 4|. Engagement of the adjacent end of the stop screw 60 with the abutment ear 5| positively limits the lateral movement of the rear end portion of the control finger 53 in the direction of the base 2. Intermediate the lug 59 and the ear 55 of the control finger 52 is a laterally outwardly projecting tongue 52 which is positioned to engage the head l! of the switch operating shaft 455. The shaft 45 and its cooperating rod 52 are axially parallel to the lateral direction of movement of the control finger 53, see Figs. 2 and 3. The above-described means for mounting the control finger 53 provides for extreme case of movement of the control finger so that bags A of thin relatively flimsy material will move the control finger without buckling or otherwise being deformed. Engagement of the presser foot 5 of the bag top on opposite sides of the control finger 53 further adds to the support of the bag top and effectively prevents damage to the bag tops during the stitching operation which would otherwise sometimes occur due to lack of proper support.

As clearly shown in Figs. 2 and 3, when a bag A enters the machine between the base plate 2| and the presser foot 5, the top portion of the bag A engages the outwardly curved portion 51 of the control finger 53 and tends to displace the same by camming action thereagainst. The pivotal mounting of the control finger 53 tends to retain the rear end portion of the control finger in the slot 5| of the base plate 2|. It should be noted that at this point, the stop screw 55 is in abutting engagement with the abutment ear 6| whereby to provide a fulcrum about which the control finger swings during its initial laterally outward movement. It will be seen, by reference to Figs. 2 and 3, that the control 53 acts as a lever having a relatively short lever arm between the stop screw iill and the head-engaging tongue 52, and a relatively long lever arm between said tongue and the front bag-engaged portion of the finger 53. Thus, very little laterally outward pressure is required to the front end 5'! of the control finger to close the control switch in the housing 39 whereby to energize the solenoid in the casing 35 to initiate operation of the stitching means and thread cutting mechanism. As the bag A is fed through the machine, the control finger 53 is gradually moved out of the slot 5| in the base plate, the finger being held against longitudinal movement by the pivoted rigid link -5. During this time, the stop screw is moved out of engagement with the abutment ear GI and the entire bias of the switch toward its normally open position and the overtravel spring 50 is exerted against the top of the bag A. Dur ing this time, however, a sufficient amount of bag material has advanced between the control finger and the base plate 2i to adequately resist said bias without giving way until the stitching operation has been completed across the entire width of the bag top. As the bag leaves the machine, moving from left to right, with respect to Figs. 2 and 3, the control finger 53 is again permitted to move laterally toward the base plate and enter the slot 5! thereof and cause the switch to open thereby uncoupling the stitching and thread cutting mechanism from the motor 26. It should be noted that there is suiiicient kinetic energy in the stitching and thread cutting mechanism to cause the same to continue operating for a very brief interval after the switch has been opened. During this time, the stitching thread laterally outwardly of the stitched bag is moved into operative engagement with thread cutting mechanism by mechanism now to be described. The thread cutting mechanism includes a station ary cutting blade 53 and a movable blade 6 5, see particularly Figs. 2, 3 and 7. The stationary blade "63 is suitably anchored in the base 3 and the movable blade at is mounted on a swinging arm pivotally mounted in the base 3, as indicated at 65. Reciprocatory movements are im parted to the movable blade Si by the drive shaft 3 through suitable mechanism including a lever arm 8i pivotally mounted at its intermediate portion to a bracket 58 mounted in the base 3. The above-described cutting mechanism is fully disclosed in our pending application above identified. The base 2 and the base plate 2i are provided with openings 6% and iii respectively through which the stitching thread is moved into operative engagement with the cutting blades 53 and 54. A fluid pressure cylinder "H is rigidly mounted on the bracket ti in closely spaced parallel relation to the bearing sleeve 43 and has mounted for reciprocatory movement therein a piston 72 carrying a cross-sectionally rectangular plunger rod 73 which projects outwardly therefrom in the general direction of the base 2 which terminates in a fork-like stitching thread engaging head it. As shown, in Fig. 8, a coil compression spring it biases the piston 12 in a direction to retract the head E iout or the path of travel of the upper ends of the bags A.

Means for introducing fluid under pressure to the cylinder l'i whereby to project the thread engaging head i l into engagement with the stitched thread and carry the same between the cutting blades 63 and s4 comprises a conduit l5 leading to a valve El secured by means of a bracket it to the solenoid housing 35. The valve i? is illustrated in Fig. 6 and comprises a valve body it having therein an air inlet passage $0 from which extends a conduit 8! which may '2 be assumed to be connected at its other end to a source of fluid, such as air, under pressure. The passage terminates at its inner end in a transverse bore 82 and in which is mounted for axial movements a valve stem 83 having a diametrically reduced intermediate portion 84. The stem BSprojects laterally outwardly from one side of the valve body 19 and is yieldingly biased in a direction ou wardly therefrom by a coil compression spring interposed between the inner end of the stem 83 and the bottom of the bore 82. A second passage 86 extends from the bore 82 in laterally offset relation to the passage 88 and communicates with the conduit 7%. A third passage 8'! extends outwardly from the bore 82 in laterally spaced relation to the passages 8t and 86 to atmosphere. The construction is such that, when the stem 83 is moved inwardly against bias of the spring 85, the reduced portion of the stem 33 will be in register with the passages 8% and 56 thereby permitting air under pressure to be introduced to the cylinder H in a direction to project the head-e uipped piston rod '53 and piston '52 in a direction generally toward the cutting blades. At this time, the third passage 37 to atmosphere is shut off from both other passages 39 and 8B. When the valve stem 33 is permitted to return to its position of Fig. 6, the passages 8% and 8! are in register with the reduced portion 84 of the valve stem and the piston '12 and parts carried thereby will move in a direction to retract the head it generally away from the cutting blades and out of the path of travel of the bags being fed through the machine under bias of the return spring 35. The valve stem 33 is moved inwardly of the valve body 19 by a lever 88 pivotally secured at its upper end to the bracket it, as indi-- cated at 89. The lower end of the lever 88 is provided with an adjustable stop screw which has abutting engagement with an arm extension 9i that is anchored at its lower end to the arm 38 of the clutch lever 35. With reference to 1, it will be seen that, when the clutch element is in its operative position, shown by full lines, the lever 88 is moved to a position wherein the cylinder H is open to atmosphere through the conduit it and the passages 86 and 81 of the valve H. In this position, the head M of the plunger rod i3 is retracted and the bag A permitted to pass therebeyond. Immediately upon opening of the switch 35 and consequent deenergization of the solenoid in the casing the spring 35 will move the clutch element as to its inoperative dotted line position ofl ig. 1. This movement causes the arm 9! to move the lever 88 and the valve stem 83 into the position where air under pressure is admitted to the cylinder ll through the conduit 6!, the interccmmunicating passages 89 and 8t, and the conduit 16, the pressure being great enough to overcome the bias of the spring '55 in the cylinder ii and project the plunger rod it to a point where the stitching thread engaged by the head is thereof is moved through the openings es and i8 and between the cutting blades 63 and ed.

The entire device may be easily applied to stitching machinery in which the thread cutting means is offset from the path of travel of the bags, it being only necessary to out the slots 5! and 52 in the base plate 2! and presser foot 6 respectively, inasmuch as the control finger 53, the head-equipped plunger rod '33, and the switch and operating head 4'! thereof are all carried by the bracket 4|.

Our invention has been thoroughly tested and found to be completely satisfactory for the accomplishment of the objectives set forth; and while we have shown and described a preferred embodiment of our novel control mechanism, it will be understood that the same is capable of modification without departure from the spirit and scope of the invention, as defined in the claims.

What we claim is:

1. An attachment for sewing machines having 7 means for stitching articles successively fed in spaced relation, means including a clutch mechanism for operating the stitching means, mechanism for cutting the stitching thread outwardly of opposite sides of said articles, and bag actuated control means for said operating means; said attachment including an elongated reciprocatory member, a fork-like head on said member, said head comprising a pair of thread engaging fingers diverging longitudinally outwardly of one end of said member; a cylinder mounting and guiding said reciprocatory member for 1ongitudinal reciprocatory movements or" the head thereof transversely through the path of travel of the stitching thread in spaced relation to the stitching means and in a direction to carry said thread into engagement with the thread cutting mechanism; means mounting said cylinder in spaced relation to the stitching means in the direction of feeding movement of said articles;

fluid pressure operated means for imparting movements to said member in one direction, said fluid pressure operated means including a conduit communicating at one end with said cylinder and adapted to be connected at its other end to a source of fluid under pressure, a valve interposed in said conduit, and a piston element on said reciprocatory member; yielding means biasing said member in opposition to the fluid pressure exerted against the piston thereon; and

operating connections between said clutch mechanism and said valve, operating connections including a valve operating lever.

2. An attachment for sewing machines having means for stitching articles successively fed in spaced relation, means including a clutch mechanism for operating the stitching means mechanism for cutting the stitching thread outwardly of opposite sides of said articles, and bag actuated control means for said operating means; said attachment including an elongated reciprocatory member, a fork-lil e head on said member, said head comprising a pair of thread engaging fingers diverging longitudinally outwardly of one end of said member, a fluid pressure cylinder mounting and guiding said member for longitudinal reciprocatory movements of the head thereof transversely through the path of travel of the stitching thread in spaced relation to the stitching means and in a direction to carry said thread into engagement with the thread cutting mechanism; means mounting said cylinder in spaced relation to the stitching means in the direction or" fee-ding movement of said articles, a piston mounted on said member within the cylinder for common reciprocation therewith, a conduit communicating at one end with one end portion of said cylinder and adapted to have its other end connected to a source of fluid under pressure, a valve interposed in said conduit, valve-operating connections on said clutch mechanism for positioning said valve to admit fluid under pressure to said cylinder to impart movement to said reciprocatory member in the direction of said thread-cutting mechanism, and yielding means in said cylinder biasing said piston and member in the opposite direction.

3. In a sewing machine; means for stitching articles successively fed in spaced relation, said means including a base plate and a sewing head; said head having a presser foot and a cooperating needle; mechanism for cutting the stitching thread in laterally outwardly spaced relation to said articles; driving means including clutch mechanism for imparting sewing movements to the needle and thread-cutting movements to said mechanism; common control means for said needle and cutting mechanism, said control means comprising a clutch-actuated solenoid and a switch therefor; a finger normally lying in a position within the path of travel of said articles adjacent said presser foot and yieldingly biased toward said position, said finger being movable by said articles to operate said switch; and means for moving the stitching thread into engagement with the thread-cutting means responsive to operation of said control means to stop the stitching and cutting mechanisms, said stitching thread moving means comprising an elongated reciprocatory member, a fork-like head on said member, said head comprising a pair of thread engaging fingers diverging longitudinally outwardly of one end of said member, a cylinder mounting and guiding said reciprocatory member for longitudinal reciprocating movements of the head thereof transversely through the path of travel of the stitching thread in spaced relation to the stitching means and in a direction to carry said thread into engagement with the thread cutting mechanism; means mounting said cylinder in spaced relation to the stitching means in the direction of feeding movement of said articles, fluid pressure-operated means for imparting movements to said member in one direction, said fluid pressureoperated means including a conduit communicating at one end with said cylinder and adapted to be connected at its other end to a source of fluid under pressure, a valve interposed in said conduit and a piston element on said reciprocatory member, yielding means biasing said member in opposition to the fluid pressure exerted against the piston thereon, and operating connections between said clutch mechanism and said valve and including a valve operating lever.

4. In a sewing machine, means for stitching articles successively fed in spaced relation, said means including a base plate and a sewing head, said head having a presser foot and a cooperating needle, mechanism for cutting the stitching thread in laterally outwardly spaced relation to said articles, driving means including clutch mechanism for imparting sewing movements to the needle and thread-cutting movements to said mechanism, common control means for said needle and cutting mechanism, said control means comprising a clutch-actuated solenoid and a switch therefor, a finger normally lying in a position within the path of travel of said articles adjacent said presser foot and yieldingly biasing toward said position, said finger being movable by said articles to operate said switch,

and means for moving the stitching and cutting mechanisms, said stitching thread-moving means comprising an elongated reciprocatory member, a fork-like head on said member, said head comprising a pair of thread engaging fingers diverging longitudinally outwardly of one end of said member, a fluid pressure cylinder mounting and guiding said member for longitudinal reciprocatory movements of the head thereof transversely through the path of travel of the stitching thread in spaced relation to the stitching means and in a direction to carry said thread into engagement with the thread cutting mechanism; means mounting said cylinder in spaced relation to the stitching means in the direction of feeding movement of said articles, a piston mounted on said member within the cylinder for common reciprocation therewith, a conduit communicating at one end with one end portion of said cylinder and adapted to have its other end connected to a source of fluid under pressure,

a valve interposed in said conduit, valve operating connections on said clutch mechanism for 5 positioning said valve to admit fluid under pressure to said cylinder to impart movement to said reciprocatory member in the direction of said thread-cutting mechanism, and yielding means in said cylinder biasing said piston and member 10 in the opposite direction.

References Cited in the file of this patent Number UNITED STATES PATENTS

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