US2674964A - Spiral stitch mechanism for sewing machines - Google Patents

Description

April 13, 1954 A. GUIDE SPIRAL STITCH MECHANISM FOR SEWING MACHINES Filed May 27, 1952 2 Sheets-Sheet 1 FIG.

INVENTOR.

Gan/Z BY ATTORNEY A. GUIDE April 13, 1954 SPIRAL STITCH MECHANISM FOR SEWING MACHINES 2 Sheets-Sheet 2 Filed May 27, 1952 INVENTOR.

ATTORNEY Patented Apr. 13, 1954 UNITED STATES PATENT OFFICE SPIRAL STITCH MECHANISM FOR SEWING MACHINES 9 Claims.

The present invention relates to sewing machines and more particularly to a method and means for producing a spiral seam on a workpiece. In its more specific aspects the invention undertakes to render available an efficient apparatus for producing a spiralling seam or line of stitches on cup-shaped brassiere elements or other shaped forms of work as well as on flat work.

Another objective of the invention is the construction of a spiral stitching mechanism, preferably but not necessarily, in the form of an attachment that may be conveniently applied to existing sewing machines and to cooperate with the conventional stitching mechanism to cause the resulting seam to be formed in a spiral with one or more spaced convolutions. The invention further aims to provide a mechanism for producing a spiral seam on relatively large or relatively small work pieces and one that is capable of convenient adjustment so that the spacing of the convolutions of the spiral may be altered to suit the nature of the work, the needs, or ones preferences as to the number of convolutions to be produced on a given piece.

In some respects the present invention and application is a continuation in part of my earlier filed application, Serial No. 268,954, filed January 38, 1952, but which, however, is a distinct improvement over the earlier structure, not only in simplicity in design and operation, but .in an improved relation and coaction of cooperating elements by means of which the efficiency, versatility, and range of the spiral seam producing mechanism is greatly increased.

The present invention proposes a simple mechanism that may be a built-in part of a sewing machine or which may be constructed as an attachment. Essentially the invention comprises a movable work guide that carries a center on and about which a preformed brassiere cup or similar workpiece is revolvably fixed, and a transmission train between the main drive of the machine and the movable work center. The transmission train includes a cam and lever system and preferably a change-speed means,

whereby the rate of movement of the work center relative to the speed of the machine may be varied at will. The parts are so constructed an. arranged that the stitching is done on the inside of the brassire cup, that is, the cup is placed on the work-guide center and held at its polar axis by a piercing point a short distance laterally offset from the needle of the machine. One side spherical contour of the cup makes, accordingly,

a localized engagement with the feeder teeth but never-the-less an engagement adequate to feed the material. As the stitching progresses, the cup being transfixed by the pin at its polar axis, is free to revolve and does revolve about that axis. Simultaneously the cam and lever system is caused to operate slowly, and through the means to be described, effects a shifting of the polar axis of the work laterally in timed relation with the stitching and in proportion to the ever changing size of the spiral to be formed. The present spiraling device is especially useful in connection with sewing machines equipped with devices for changing the length of the stitch, for when the length of the stitch is increased, the spacing of the convolutions of the spiral become closer, because the machine speed and cam speed remain constant, but the number of stitches per inch of work travel decreases whereby convolutions of the spiral become more closely spaced. However, to vary the spacing of the spiral convolutions, the ratio between stitching-speed and cam-speed must change, and this is readily effected by speed varying means provided in the drive train to the work carrying center. The present invention, therefore, comprehends a machine driven mechanism for automatically producing spiral seams on hemispherical work and with which the size of the stitch, as Well as the spacing of the convolutions of the spiral, may be independently varied to suit particular requirements.

Other objects and advantages will be in part indicated in the following description and in part rendered apparent therefrom in connection with the annexed drawings.

To enable others skilled in the art so fully to apprehend the underlying features hereof that they may embody the same in the various ways contemplated by this invention, drawings depicting a preferred typical construction have been annexed as a part of this disclosure and, in such drawings, like characters of reference denote corresponding parts throughout all the views, of which:

Figure l of the drawings is a plan view of a spiral stitching machine embodying this invention, parts of the conventional sewing machine being omitted.

Figure 2 is a side elevational view of Figure 1.

Figures 3, 4 and 5 are respectively plan and sectional views of portions of the cup centering and stitch feed means.

Figures 6 and '7 are representative views of a spirally stitched brassiere cup.

Referring more particularly to Figure 1, the invention. disclosed. has been illustrated in the form of an attachmentcapable of ready application to a conventional sewing machine whereby the latter, without serious alteration or delay may be quickly converted to a machine for spiral stitching of hollow work. The principle, of. this invention may of course be embodied in a custom built machine, as will be understood. In the form illustrated, however, the main elements of the invention are supported upon, a. relatively thin plate herein illustrated as three plates It, i I, and [2 that are placed about the bedplate E3 of the sewing machine l4 and suitably secured to the tabletop 1-5 In the instant embodiment the upper surfaces of the plates lie substantially in the plane of the upper surface of the bedplate [3 and form in eifect, a continuation of. the working surface thereof.

'The sewing machine indicated at M is of conventional-design having the customary upper and lowerthread guides, needle carrier, presser foot and feed jaws indicated at l 5 and H. respectively in Figures Bands. In accordance with this invention thepresser foot i5 and the feed jaws H are especially constructed sothat they are efiective only at one side of the needle l8 whereby the forward feed; of the material is caused to occur primarily at that one side, preferably the Wheel head sldeof the needle it; A. work supporting guide 59 which holds thev work centering means 2%, is positioned at the other side of the needle. The work supporting guide comprises in this instance a. relatively long lever member that is pivoted at 21 to the plate I2 at the operators side of the machine and carries adjacent the sewing needle a removable work centering piece 22. The centering piece 22 isprovided with an opening at Z-Qadapted to receive a work piercing point 23. The point. 23. is. carried at the free end of an over-arm 2s thatv in turn is mounted to a block or weight 25 which. has an offset pivotal mounting. 25' in a support 2?. Support 21 is mounted upon and is carried by. an extension 28 of lever l3 sothat the overarm Mend centering means 2E3 and 23 may. move laterally as a unit. Lever it, as indicated in Fi ure 1, has its pivotal axissubstantially aligned with. the normal line of. feed of the sewing machine so that as the workguide is moved angularly about that point, the work centering means 28 and 2! move in an arc in a direction substantially normal to the direction of feed produced by the modified presser foot l6 and feed jaws I"! of the machine.

This invention proposes an efficient means for actuating and controlling the rate of lateral movement of the work center relative to the rate of forward feed whereby it becomespossible automatically to form a spiralling seam on the work piece. As illustrated. more clearly in Fig. 1, the work-guide lever 19 is fashioned with a second extension 29 whose edge 36 is curved and forms a cam-track that is normally engaged by a cam-follower roller 3 i. The follower 31 is carried by and at one end of an arm 32 that issupported upon and pivots about a pivot shaft 33. At the rear side. of thepivot 33, a curved extension St is provided, which in this embodiment may be an integral part of arm 32, and which remains substantially constant.

has its inner edge 35 especially contoured to function as a cam-track for a main actuating follower 36. The follower roll 35 is mounted upon a lever 3i that is pivotally supported for movement about an axis 38. Pivotal axis 38, 33, and 2! preferably are substantially in alignment, as illustrated, and the needle I8 stitches approximately on that line.

With reference to the position of the parts shown in Figure 1, it will be seen that when the main actuator roller 3% moves counter-clockwise about its pivot 38, it engages the cam track 35 of lever 34 and moves the latter clockwise about pivot 3'3 and its other arm 32 and follower 3| is caused to engage cam track 3% and move lever 25, it counter-clockwise about its pivot 38. The combined movements of the two cams and followers thereby causing the work supporting elements 2t, 22, and 23- to shift laterally. It will be seen further that by giving the cam track 35 a curved, formation, the work supporting center 22 and 2-3 may be caused to respond at a progressively decelerating rate, and by curving the track 36 the effectiveness of the movement imparted by levers 34 and 32 to the work support Compensation for the constantly varying angular relation oi lever 19, 29 and its actuator 32 is thus automatically made and consequently relatively large spirals may be formed.

The main actuating follower 36 and its lever 37 are propelled in this embodiment by a unidirectional ratchet gear 3s and a pawl element :38. The pawl til is pivoted at ll on the lever 37 and is tensicned by a pull-spring a2 normally into engagement with the teeth on the gear 39. The gear 39 is secured to a vertical shaft d3 which is an output shaft of a speed reducing unit R. The speed reducer may be suitably secured to the under-side of the plate I6, and comprises essentially a main housing 45 in which are journaled two pairs of worm and gear elements 55, ll, 48 and d9 arranged in series. The driven gear 49 is secured to the output shaft 43, and the driver worm it is secured to an input shaft 56. Shaft 58 extends beyond the housing 35 and is provided with an extension 50a on which a set of cone pulleys 55 may be mounted. In this embodiment, a sleeve-like support 52 is provided.

for the drive shaft extension 59c.

Power for operating the drive shaft 563a may be taken from the wheel head 14a of the machine or from the main motor of the machine, here indicated as the shaft 53, by means of a belt 5 4, and, if desired, a second set of cone pulleys 55. The belt 56 and pulley 51 are connected to drive the sewing machine as will be understood, and when this driving relation obtains its will be seen that the transmission for eifecting lateral feed of the work piece is driven in synchronism with the transmission that drives the stitch forming mechanism of the sewing machine. Assuming that the speed reduction afforded by the reducer R is on the order of 25001, and that a given step in the pulley drive 5!, 54 and 55 provides another reduction or" say 4:1, it will be seen that the rotary movement imparted to ratchet gear 39 for each stitch cycle is indeed very small, and this small movement, transmitted through the system of cam levers to the work support center 20, 22, and 23 effects an almost imperceptible lateral movement of the work. However, if the machine is set for mak ing say 12 stitches per inch, and-if a given convolution of the spiral is one inch long, themachine will have made 12 stitching cycles for that convolution and the work piece will have shifted laterally the spacing of one convolution. Accordingly, therefore, should the length of stitch be increased to ten per inch, there will have been ten stitching cycles for that convolution and the lateral shift of the work will be slightly less than before. Therefore, by suitably selecting the length of stitch, the spacing of the convolutions in the spiral may be changed to suit. Also, by increasing or decreasing the rate of speed of the lateral feed transmission relative to the rate of speed of the forward feed transmission, the spacing of the convolutions of the spiral may be varied. It has been found that a four step pulley provides ample variation to cover a wide range of work, and which in combination with the variation produced by changingstitch length as explained above, an almost infinite number of spiral spacings may be produced.

As above explained, the drive pawl 40 normally engages the teeth of the gear 39 but is arranged to be released therefrom at the end of the stitching operation by means of a release shoe 30. The shoe may be formed with a curved edge (it that lies normally within or below the point of engagement therewith of a roller 40a carried by the pawl 40. The shoe 60 is pivoted as at 62, and at a point 63, beyond its curved track portion 61, it is connected to a pull-lever 64. Lever 6 extends toward the front of the machine and is provided with a handle 65. Adjustable stop collars 66 are provided on the rod at opposite sides of a fixed abutment 61 to limit the movement of the release shoe. A pull spring 68 connected. with the shoe normally constrains the shoe out of engagement with the pawl roller tea. In the position illustrated in Figure l, the release shoe is retracted and the pawl is in the driving engagement with gear 39. However, when the handle 65 is pulled out, the shoe advances, engages the follower 40a and releases the pawl from the gear, and lateral feed of the work ceases. When the pawl is released from the gear a spring 10, connected to cam lever 32, 34 and a stationary collar ll, retracts the cam lever to starting position as determined by an adjustable stop 12 that is provided. If desired pawl lever 31 may be reset by a pulley and weight mechanism indicated at 13 to avoid using too strong a spring at 10. In either case, however, when the pawl is released, by the release shoe 30, the pawl roller 40a rides back on the track iii to its starting point as may be determined by a stop pin M. Stopping of the lateral feed automatically at a selected point may be obtained by the provision of an enlargement of the shoe track as indicated at Bla. As the pawl lever 3'1 moves counter-clockwise under the impulse of the ratchet gear 39 the pawl roller 40a, will at the selected point, engage the lobe Bla and be cammed out of the teeth of ratchet gear, thus suspending the drive.

In the styling of brassiere elements, one may with the present invention commence forming the spiral seam with the first few stitches or cause the spiral to run out of a small circle at the polar axis of the cup. If the former is desired, the stop 14 is adjusted to the position illustrated in Figure 1 wherein the pawl 31 is retracted to a position such that the roller 36 engages the beginning of the cam track 35 of lever 34. As soon as the stitching starts, therefore, the pawl lever roller 36 begins to actuate lever 34 about its pivot 32. These movements are transmitted lever 39, through the follower 3| and cam track 30, and the work shifts laterally. When, however, a preliminary circle is desired, the stop 14 may be adjusted back from the the position shown in Figure 1 so that the follower 36 is spaced from and starts a little distance away from cam track 35. Under such conditions the initial movement of the ratchet gear and pawl lever has no effect on the cam lever 34' until the gap is taken up. The adjustment of the stop M is to be such that the stitching mechanism will have revolved the work about the center 23 one revolution during which time the pawl lever follower 36 will have traversed the gap and is in position to start actuating the lever 34. It will be observed that by properly correlating the adjustments made to the two stops [2 and 14, the work to be spirally sewn may be started with a preliminary circular seam of any desired size.

To operate the attachment, the operator will swing the work supporting lever is to the left (from the position shown in Figure l) and lift up the over-arm 24. As indicated in Figure 1, the plate I i may be formed with a curved recess I la, which receives the projecting portion of the work pivoting needle 23. After centering the work blank upon the center 20, the over-arm is lowered so as to pierce the work with its needle 23. The assembly is then moved toward the stitching needle, as the outer edge of the work is guided under the presser foot, until the center of the work occupies a position close to the stitching needle L8, or such distance therefrom as determined by the adjustable stop 12 which locates the follower 3! against which the work supporting lever stops. The presser foot is then lowered on the work, and after replacing a shield 80, the sewing machine may be started. By virtue of the forward feed of the material being effected and confined to that side of the stitching needle is opposite the center about which the work revolves, renders the operation of revolving the work as an incident of the forward feed motion, easy of accomplishment, even on fairly delicate materials.

The shield 89 is provided to aid in holding hemispherical work open and to facilitate the feed thereof under the presser foot IS. The shield as may be supported at the end of a looped rod 8! that is carried by a weighted pivot block 82, the latter being pivoted as at 83 to bracket carried on the plate l2. In removing and replacing work this shield may be lifted out of the way, as will be understood.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various utilizations by retaining one or more of the features that, from the standpoint of the prior art, fairly constitute essential characteristics of either the generic or specific aspects of this invention and, therefore, such adaptations should be, and are intended to be, comprehended within the meaning and range of equivalency of the following claims.

Having thus revealed this invention, 1 claim as new and desire to secure the following combinations and elements, or equivalents thereof, by Letters Patent of the United States:

i. In combination with a sewing machine having stitch forming means including a needle, a presser foot, and feed means adapted normally to feed the work in a forward direction, means for imparting a feed movement to the work in pivot mounted above the work table and laterally offset from the needle axis of the machine, a feed transmission for actuating said pivot laterally relative to the direction of forward feed, including a rotatable member mounted above the work table, means for driving said rotatable member in synchronism with the operation of the stitch forming means of the machine, a cam lever also mountedabove the table operatively responsive to the movement of said rotatable member, motion transmitting connections be- 10 Number 10 tween said lever and said work supporting pivot. and means for varying the speed of the said feed transmission relative to the rate of forward feed incident to the stitching operation whereby to produce a spiral seam with a predetermined spacing between the convolutions of the spiral.

References Cited in the file of this patent UNITED STATES PATENTS Name Date 1,466,486 Schloss Aug. 28, 1923

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