US2988031A

US2988031A - Thread end holders for sewing machines

Info

Publication number: US2988031A
Application number: US737606A
Authority: US
Inventors: Orland B Reid
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1958-05-26
Filing date: 1958-05-26
Publication date: 1961-06-13
Anticipated expiration: 1978-06-13

Description

June 13, 1961 2,988,031

THREAD END HOLDERS FOR SEWING MACHINES Filed May 26, 1958 tion of New Jersey Filed May 26, 1958, Ser. No. 737,606 11 Claims. (Cl. 112-253) The present invention relates to sewing machines and has for an object to provide a new and improved means for holding the ends of the sewing threads during the initial stitches to prevent unthreading of the needle.

Upon the completion of a sewing operationon a sewing machine, the completed workpiece remains tied to the machine by the sewing threads which must be severed in order to remove the workpiece from the machine. Whenthe sewing threads are severed, there results the loose ends which, if they are long enough, will accommodate initiation of the next sewing operation without unthreading the needle. However, long thread ends at the beginning as wellas at the end of a seam on the workpiece areundesirable since in the finished garment they are unsightly and must therefore be trimmed, and also, since any ,threadends constitutes wasted thread. To economize on thread and at the same time eliminate the subsequent trimming operation, the thread..chain should be trimmed as close as possible to the workpiece and to the point of stitch formation, thus minimizing the length of the thread ends. In accordance with the present invention there is provided means for holdingthegloose end of the sewing threads at the beginning of the sewing operation, thus permitting relatively short thread, ends without unthreading the needle. As soon as the threads are secured to the workpiece by the formation of .a stitch or two, the thread ends are released to permit feeding of the work.

It is an object of this invention to provide aithread end holder that is efficient, reliable, durable andrelatively economical to produce. It is a further object of this invention to provide a thread end holder that .is .designed to be used in a cyclically operated sewing machine, which can be readily actuated automatically in timed relation'to the actuation of the sewingrnachine, and which is so constructed and arran gedthatit-will not interfere with the manipulation of the work onthe bed plate of the machine. I

A further object of this invention is to provide. a threa end holder thatwill position and hold thebobbin thread to prevent improper positioning thereof.

In the accompanying drawings;

FIG. l is a fragmentary view, in elevation, .offthe head end of a sewing machine embodying the presentinvention,

" FIG. 2 is a fragmentary head end view, partly in tilevation and partly in section, of the sewing machine illustratedin FIG. 1,

FIG. 3 is a detail vertical sectional view through the point'of stitch formation of the sewing machineof FIGLl,

FIG. 4 is a fragmentary horizontal sectional view above the throat plate of the sewing machine of-FIG. 1.

The present invention in herein disclosed as embodied in the automatic cuff sewing machine that forms the. subject matter of copending application Serial No. 737;:775, filed May 26, 1958, to which referencemay be had for a more complete understanding of the"machine.The automatic cult sewing machine is herein disclosed only insofar as is necessary to' obtain a full understanding of the present invention. "jlllith reference to the drawings there is disclosed a sewing machine I mounted upon a table 2 and having a bed including a bed plate 3, the upper surface of which come prises the .work supporting surface of the machine, and ,a bracket arm 4 terminating in a head 5 overhanging the bed plate, 3. A needle bar 6 is mounted in the head-5 for vertical endwise reciprocation and at its lower end carries -a needle 7 that cooperates with a rotary hook 8 joumaled in the bed of the machine in the formation of two-thread lock stitches by the concatenation of a needle thread 9 threaded through the eye of the needle 7 anda bobbin thread 10 that emerges from the'bobbin case 11 carried bythe rotary book 8. About the point of stitch formation, the bed plate 3 is provided with'a throat plate -12 having a needle aperture 13 through which the needle 7. passes .during stitch formation. Also mounted vertically-.inthe head 5 for endwise reciprocation is a;.pr.ess er bar 14 carrying apresser foot 15 at its lower end for holding the work down against the throat plate 12,-the presser;foot 15 having a needle hole 16 in alignment with theneedle aperture 13 in the-throat-plate 12 and-through whichthe needle 7 also passes during stitch formation.

The thread end holder is carried by a mounting .plate 17 secured as .by screws 18 to the face plate19 that .closes-theopen end of the head 5. Mounted onztheupper portion ofthe, plate 17, is a cylinder 20-having antinternal cylindrical piston chamber 21. (The open'cbottomQofthe piston chamber '21 is closedibya cylinderThead 22 secured to the cylinder- 20 by .:screws:23.;that.are threaded; into lugs? 24 on opposite sidesof-the. cylinder 20.

qWithin the. piston chamber-21 there is disposed at pistonf25 mounted upon the end portion 26015 a twopart piston rod 27 ithatextends downwardly through the cylinderhead 22 and .is mounted for endwise sliding movementfin a bushing; 28 on the cylinder headl22. The-lower portion 29 of the rod 27. is reduced and is guided-bya bracket 30 mounted on the lower end ofthe'plate 17 by screws'31 and having an apertured ear 32 throughwhich the rod extends. For \guiding the rod 27to prevent-it from turning, there is mounted on the lower portion 29% collar 33 having a laterally extending arm-'34 that proiects through a slot 35 in the mounting plate 17. A-coil compression spring -36 is disposed in the pistontchamber 21 between the piston 25 and the cylinderhead 22 to bias the piston upwardly. Forforcing the -piston'25 downwardly and-thereby depressing the rod 27,- the upper end of the piston chamber 21 above the piston' 25' is connected by a tube 37 to a solenoid-actuated valve unit 38 mounted upon the underside of the table 2. The unit 38 is connected by a tube 39 to a source of compressed air and includes an air valve that will lead compressed air from the tube 39 intothetube-37 when the solenoid is energized by power supplied through. the wire .40.

Upon the lower end .of the rod'27 there .is mounted a clamping foot 41 having a rearwardlyextending cylindrie cal stud 42 mounted on a horizontalaxis in a :borein a mounting shank 43 that in turn'has abore into which the lower end .29 of the rod 27 extends and'in which it is secured by a set screw 44. The clamping foot '41'is thus free to turnabout a'horizontalaxis to provide for automatic leveling of the foot 41 relatively to the throat plate 12. Turning of the foot 41 is limited by a pin 45 on the stud 42 that is received in a groove 46 .in the shank 43. To insure a secure clamping by the foot 41 of the loose ends of the threads 9 and '10, which are designated47 and 48 respectively, the-throat plate 12 is provided witha roughened surface 49 in the area engaged by the foot 41.

To position the

thread ends

47 and 48 under'the clamping foot 41 there is provided a blower comprising a bore or nozzle 50 in thethroat plate 12 that is arranged 'at such an angle that'the air emergingtherefrom-will carry the thread ends under-the foot 41. The-bore 5tl communicates with a nipple 51 mounted on the underside of the throat plate 12 and connected by a tube 52 with a source of compressed air.

To prevent breaking the needle thread 9 while the end 49 thereof is clamped by the foot 41 and when there is not sufiicient thread in the thread system of the machine to accommodate the take-up action, there is provided an arm 53 pivotally mounted on the bracket 54 and having an end engaged by the collar 33 when the clamping foot 41 is lowered. The other end of the arm 53 extends around the head to engage and release the needle thread tension device as shown in FIG. 2.

In the operation of the present thread end holder, the thread ends are blown under the clamping foot 41 by the air emerging from the nozzle 50. Before the operation of the sewing machine 1 is initiated, the solenoid of the valve unit 38 is energized from a control mechanism through the wire 40 to conduct compressed air from the tube 39 to the tube 37 and thus to the piston chamber 21 above the piston 25 to force the piston and the piston rod 27 downwardly against the action of the spring 36. As the piston rod 27 moves downwardly, the clamping foot 41 which is carried by it is forced downwardly against the throat plate 12. The clamping foot 41 is held down only until the threads are locked in the work by the formation of a few stitches. The thread ends are then released by deenergization of the solenoid of the valve unit 38, which closes the supply of air pressure to the tube 37, thereby permitting the spring 36 to raise the piston 25 and thus lift the clamping foot 41.

In the illustrated machine, at the initiation of the sewing cycle, the direction of feed is in the direction of the arrow A in FIG. 4 and the work is arranged to the right of the point of stitch formation which is defined by the needle 7, or in other words, coincides with the needle aperture 13 in the throat plate 12. To insure that the clamping foot 41 does not engage the work and also to insure that the thread ends 47 and 48 will not be stitched down to the work by the subsequent stitching, the clamping foot 41 is arranged laterally of the direction of feed on the opposite side of the point of stitch formation from the work. With the thread ends thus held to the side opposite from the work, the needle will descend on the right side of thread ends. At the same time, to permit feeding ofthe work relatively to the point of stitch formation while the thread ends are clamped, the nozzle 50 is arranged to blow the thread ends slightly forwardly relatively to the direction of feed. Thus, as the work is fed in the direction of the arrow A, the thread ends will in eifect pivot about the point at which they are clamped and will not be tensioned and thereby pull the work. 1 a

Another feature of this arrangement in which the thread ends are arranged laterally of the direction of feed is that with the work advancing in the direction of the arrow A, the blower will be effective until just immediately before the beginning of the stitching operation. This is important in a cyclically operated sewing machine as disclosed for example in the above noted application Serial No. 737,775, wherein the work is carried by a traversing mechanism including an arm asillustrated at.55 in FIG. 1 which carries it relatively to the point of stitch formation to produce a seam of a predetermined configuration as defined by the cycle of actuationirnparted to the arm 55.. In order to define a complete cycle there is an idlestroke during which the arm 55 must pass across the point of stitch formation, at which time thesewing machine 1 is out of operation with the needle '7 raised and the presser foot 15 and the-clamping foot- 141 .are raised. In the particular machine illustrated, this idle stroke occurs at the beginning of the cycle with the work moving in the direction of the arrow B in FIG. 4; At theend of the idle stroke, the work immediately begins to move in the direction of the arrow A, the presser foot 15 is lowered, and the operation of the sewing machine 1 4 is initiated. At this time, the clamping foot 41 must be down to hold the thread ends. Since the clamping foot 41 must be raised while arm 55 is passing under it, it cannot be lowered until only immediately before the sewing operation begins. Thus, the construction and arrangement of the thread end holder in accordance with the present invention does not include any obstructions which would impede the motion of the arm 55 across the point of stitch formation, and, at the same time, provides for operation of the thread end holder immediately before initiation of the sewing operation so that the thread ends will be properly and securely held until the initial stitches are formed.

Having thus described the nature of the invention what I claim herein is: e

1. In a sewing machine having a frame including a Work supporting surface and a head overhanging said work supporting surface, stitching mechanism including a needle bar mounted in said head for endwise reciprocation and carrying at its lower end a needle defining a point of stitch formation on said work supporting surface,a thread end holder for securing the loose ends of the sewing threads during the initial operation of the stitching'mechanism comprising a rod carried by said head for endwise movement, a clamping foot mounted upon the lower end of said rod for movement into and out of engagement with said work supporting surface upon endwise movement of said rod for clamping the I thread ends against said work supporting surface and fluid pressure means for imparting endwise movement to said rod.

2. A thread end holder for sewing machines in accordance with claim 1 in which said clamping foot is arranged to engage said work supporting surface laterally of the point of stitch formation relatively to the direction of feed.

3. A thread end holder for sewing machines in accordance with claim 1 in which said fluid pressure means comprises a piston chamber, a piston mounted in said chamber and operatively connected to said rod, means for conducting fluid pressure into said piston chamber on one side of said piston to force said rod toward said Work supporting surface, and spring means operatively connected to said rod for biasing the same in the direction away from said work supporting surface.

4. A thread end holder for sewing machines in accordance with claim 3 in which said fluid pressure means is pneumatic and in which said means for conducting fluid pressure intosaid piston chamber comprises a source of pneumatic pressure, an air valve operatively connected at one side to said source of pneumatic pressure and at the other side to said piston chamber for selectively introducing pneumatic pressure from said source to said piston chamber.

5. A thread end holder for sewing machines in accordance with claim 4 in which said air valve is solenoid actuated. a v 6. A thread end holder for sewing machines in accordance with claim 1 in which said clamping foot is pivotally mounted on said rod on an axis parallelto said work supporting surface'to provide for automaticleveling of said clamping 'foot'relative'to 'said work supporting surface. i

7. A thread end holder for sewing machines in accordance with claim 6"in which said rod has a shank to which said clamping foot is pivotally mounted and in which the pivotal connection comprises a stud on said clamping foot and journaled' in a bore'in said shank, and means for limiting turning of said stud comprising a pin'extending throughsaid stud, 'said shank having a groove for receiving said" pin and'providing for limited turning of said pin therein. a I w -8. Athread end holder for sewing machinesin accordance with claim l having means for positioning-the loose thread. ends b i fiath said work clamping foot comprising 5 a source of compressed air and a nozzle for directing a stream of air across said point of stitch formation and beneath said clamping foot.

9. A thread end holder for sewing machines in accordance with claim 8 in which said nozzle emerges from beneath said work supporting surface.

10. In a sewing machine having a work supporting surface and stitching mechanism for defining a point of stitch formation on said work supporting surface, a thread end holder for securing the loose ends of the sewing threads during the initial operation of said stitching mechanism comprising a clamping foot, means mounting said clamping foot for movement into and out of engagement with said work supporting surface for clamping the thread ends against said work supporting surface, air pressure actuated means for moving said clamping foot into thread end clamping engagement with said work supporting surface, and means for positioning the loose thread ends beneath said work clamping foot comprising a nozzle for directing a stream of air across said point of stitch formation and beneath said clamping foot.

11. In a sewing machine having a frame including a bed plate and a head overhanging said bed plate, said bed plate having a separable throat plate disposed beneath said head and the upper surface of which together with the upper surface of said bed plate comprise a work supporting surface, said throat plate having a needle aperture, stitching mechanism including a needle bar mounted in said head for endwise reciprocation and carrying at its lower end a needle that penetrates said throat plate through said needle aperture during stitch formation and thereby defines a point of stitch formation on said throat plate, and means for positioning the loose ends of the sewing threads on said throat plate comprising a nozzle formed in said throat plate and emerging on the work supporting surface thereof at a point spaced from said point of stitch formation, said nozzle being arranged to direct a stream of air across said point of stitch formation, and means on the underside of said throat plate for connecting said nozzle to a source of air pressure.

References Cited in the file of this patent UNITED STATES PATENTS 788,212 Lyons Apr. 25, 1905 1,214,170 Kiewicz Jan. 30, 1917 2,400,741 Christensen et al May 21, 1946 2,445,629 Newton July 20, 1948 2,450,043 Haas Sept. 28, 1948 2,508,236 Enos May 16, 1950 2,827,867 Happe Mar. 25, 1958