US2072967A

US2072967A - Continuous variable stitch sewing machine

Info

Publication number: US2072967A
Application number: US744642A
Authority: US
Inventors: Roseman Leo
Original assignee: Individual
Current assignee: Individual
Priority date: 1934-09-19
Filing date: 1934-09-19
Publication date: 1937-03-09
Anticipated expiration: 1954-03-09

Description

March 9, 1937. ROSEM-A-N CONTINUOUS VARIABLE STITCH SEWING MACHINE Filed Sept. 19, 1934 l0 Sheets-Sheet l QM m a w own Q QM wwn l. M. NM:

Z VENTOR I BY M A TORNEY March 9, 1937. L. ROSEMAN CONTINUOUS VARIABLE STITCH. SEWING MAGHINE Filed Sept. 19., I954" 10 Sheets-Sheet 2,

2 l ENTOR A ORNEY March 9, 1937. L.. ROSEMAN 2,072,967

CONTINUOUS VARIABLE STITCH SEWING MACHINE Filed Sept. 19, 1954 10 Sheets-Sheet 5 w w, BYjWM.

AT ORNEY March 9, 1937. L. ROSEMAN 2,072,967

CONTINUOUS VARIABLE STITCH SEWING MACHINE I Filed Sept. 19, 1934 10 Sheets-Sheet 4 lill IVENTOR ORNEY March 9, 1937. R N $072,967

CONTINUOUS VARIABLE STITCH SEWING MACHINE Filed Sept. 19, 1954 10 Sheets-Sheet 5 T ORNEY March 9, 1937. 1.. ROSEMAN CONTINUOUS VARIABLE STITCH SEWING MACHINE Filed Sept. 19, 1934 10 Sheets-Sheet 6 VIlIl/lIlIl/l VENTOR March 9, ROSEMAN 2,072,967

CONTINUOUS VARIABLE STITCH SEWINGMACHINE Filed Sept. 19, 1954 10 Sheets-Sheet 7 A ZORNEY March 9, 1937. L, RO EM AN 2,072,967

I CONTINUOUS VARIABLE STITCH SEWING MACHINE Filed Sept.'l9, 1954 10 Sheets-Sheet 8 l I Chang: 1 f I 339 1; CI iNV NTOR l BY j r M I A ORNEY March 9, 1937. 1.. ROSEMAN CONTINUOUS VARIABLE STITCH SEWING MACHINE l0 Sheets-Shee t 9 Filed Sept. 19, 1934 1 VENTOR 7 A ORN EY March 9, 1937. 1... ROSEMAN CONTINUOUS VARIABLE STITCH SEWING MACHINE Filed Sept. 19, 1954 10 Sheets-Sheet 10 -AT ORNEY Patented Mar. 9, 1937 CONTINUOUS VARIABLE STITCH SEWIN MACHINE Leo Roseman, Newark, N. J.

Application September 19, 1934, Serial No. 144,642 I 16 Claims.

This invention relates to a sewing machine of the general type disclosed and claimed in my copending application Serial No. 736,806, filed July 25, 1934.

A prime object of the invention is to provide a novel and improved sewing machine whereby a continuous line of stitches can be formed automatically to include at either uniform or nonuniform intervals a large number of stitches of different lengths, and diflerent character, groups of superposed stitches and gaps between stitches or groups of stitches.

Another object is to provide a machine of this character which shall be capable of automatically of performing continuously and in predetermined manner, different operations at different intervals.

A further object is to provide such a machine which shall be capable of performing such operations with extreme accuracy, whereby a long line of stitches can be formed without material variations in the desired predetermined lengths of stitches, intervals of spacing, location of gaps and groups of superposed stitches, etc. or While the present invention may be utilized for stitching for difierent purposes, it is especially. adapted for use in stitching together two pieces of material between which a clasp steel or hooks l and eyes of a corset are arranged. In such gether and turned back upon each other at the seam, the seam having openings or gaps through which project the laterally projecting clasps of a clasp steel or hook, eyes or other fasteners. These clasps and hooks and eyes are also of matically in a continuous operation a long line of stitches of different lengths, diflerent spacing and different character with such extreme precision. Heretofore, it has been a diflicult and tedious operation, to make such stitches, the spacing of the gaps having been preliminarily marked on the fabric, whereupon the operator has had to form with a known sewing machine a structures two pieces of fabric are sewed todifferent widths and spaced alongthe seam varyline of stitches between each two adjacent gaps, stop the machine, manually advance the work to 1 skip stitches to form the gaps,-and continue thus throughout the length of the garment edge. Generally no reenforcing stitches have been 5 formed at the ends of the gaps, but rather a second line of stitches has been made over the first line. Where reenforcing stitches have been made, usually they have required separate operations. 10

In accordance with my invention, I contemplate I forming the gaps by long stitches or by skipping stitches, and making the'reenforcing stitches at the ends of the gaps in the form of groups 01' superposed stitches; and a prime object ofmy l5 invention is to provide a novel and improved machine for forming in one continuous operation a continuous line of stitches including stitches of difierent lengths and alined groups of stitches spaced apart predetermined distances with gaps 20 between them, so that said machine may be used to sew a seam of the general character described in a corset or the like. i I

In carrying out my invention, I may utilize a sewing machine which includes a. drive shaft, 25 and a. work feed dog which is operatively connected to the drive shaft by two connections one of which moves the dog horizontally back and forth while the other actuates the dog vertically up and down, the dog being raised'and moved 3o horizontally in one direction in engagement with the work to move the latter and then being lowered away from the work and moved horizontally in the other direction to its initial position. -'35 In accordance with the invention, the horizontal movement of the feed dog is reversed at predeterminedintervals to form the groups of superposed stitches. Where the work to be operated upon, for example, the edge of a corset. 40'

or a long strip of tape, causes substantial resistance to movement by the work feed dog, unless some means is provided for assisting the feed dog in movement of the work, slippage might occur between the work and the feed dog which would make it impossible to accurately locate the group stitches and gaps. Therefore, another ob- .iect of the invention is to provide a novel and 7 improved combination of the usual horizontal 1 and vertically movable work feed dog and an auxiliary work feed m'echanism to control feed of the work being sewed and ensure accurate spacing in predetermined relation of the groups of superposed stitches and'gaps.

The feed dog moves the work step-by-step and remains horizontally stationary during reversal group stitches, slack is produced in the work by reversal of feed thereof, and to avoid accumulation of the slack from successive reversals of or backward movement of the work, I provide means for compensating, absorbing or taking up the slack during formation of the stitches as the work is advanced in the forward direction.

In my aforesaid copending application, I have 7 shown a mechanism including a rotatable cam having cam projections on its periphery for actuating the feed dog horizontally and causing reversal of the horizontal movement thereof, each complete revolution of the cam causing the same character and sequence of movements of the feed dog. Obviously the number of stitches which can be formed by one complete revolution of such a cam must be small because the diameter of the cam is practically limited by the space available, while the cam projections for each stitch requires a certain minimum portion of the circumference of the cam, for example, one

eighth of an inch, for actuation of the feed dog through the train of levers, links and shafts Where a longer line of stitches is to be formed having the stitches with many different variations in length or spacing at different parts of the line, such a cam is not suitable. Therefore, another object of my invention is to provide a novel and improved rotatable cam which shall have a cam surface of a length many times' greater than the length of the periphery of the cam in a plane perpendicular to the axis of rotation of the cam and capable of producing series of stitches of different lengths upon successive revolutions of the cam so that the cam shall be capable of producing a long line of stitches having stitches of many different lengths and differently spaced throughout the line of stitches.

Other objects are to provide a novel and improved combination of such a cam with the drive shaft of a sewing machine and the work feed dog; to provide a cam of the character described which shall include a helical cam surface, in combination with novel and improved means for relatively moving said cam surface and a follower therefor so that the follower shall contact with said helical cam surface throughout the length thereof; to provide novel'and improved means for returning the follower and the starting point of said cam surface into co6perative relation after each complete traverse of. the follower over the cam surface; to utilize a helical rib for operating one part and the groove between the convolution of the rib for operating another part; and to obtain other advantages and results as will be brought out by the following description.

Referring to the accompanying drawings in which corresponding and like parts are designated throughout the several views by the same reference characters,

Figure 1 is a front elevation of a sewing machine embodying my invention.

Figure 2 is a bottom plan view thereof.

Figure 3'is a fragmentary top plan view of the machine.-

ing the cam being returned to its starting position.

Figure 9 is a horizontal sectional view on the line 99 of Figure '7.

Figures 10 and 11 are vertical sectional views on the line Ill-ll of Figure 9 showing operation of the mechanism for releasing the nut which actuates the cam longitudinally.

Figure 12 is a horizontal sectional view throug a modified form of the cam. b Figure 13 is a similar view showing portions of the cam surface removed from the drum.

Figure 14 is a vertical sectional view on the line l4l4 of Figure 12.

Figures 15, 16, 17, and 18 are schematically transverse vertical sectional views through the work feed mechanism showing the various steps in the operation of making one stitch in the forward direction of the work.

Figures 23 to 31A inclusive are schematic side elevations of a piece of work and the work feed dog illustrating the'formation of the stitches.

Figures 19, 20, 21, and 22 are views similar to' Figures 15 to 18 inclusive illustrating the steps in the formation of a stitch-during reverse movement of the work.

Figures 32 to 42 inclusive are views similar to Figures 23 to 31A inclusive showing successive I Figure 59 is a similar view on the line 59-58 of Figure 57. I

Figure 60 is an enlarged schematic plan view of the line of stitching embodied in the edge of the corset shown in Figure 57.

Figure 61 is a plan view of different forms of cam segments utilized for making the stitches shown in Figure 60.

Figures 61A, 61B, and 616 are continuous schematic developments of the cam surface for forming the stitches shown in Figure 60, also illustrating schematically the horizontal movements of the feed dog effected by the respective cam segments.

Figure 62 is a fragmentary vertical sectional view through the cam and showing the follower roller in side elevation to illustrate the coopera tion of the roller and cam.

Figure 63 is a horizontal sectional view on the line 63-63 of Figure 62, and

formed with a goose neck C at one end of which is mounted the needle bar D. The needle bar is driven in the usual way from the drive shaft E- ing mechanism, that is, between the needle and the bobbin mechanism, and as shown, this work feed mechanism includes a feed dog I which is movable vertically and-horizontally relative to the usual throat plate 2 in the bed of the machine, the dog being raised through the throat plate and moved horizontally in one direction in engagement with the work to move the latter and then being lowered away from the work and moved horizontally in the other direction to its initial position. The dog is operated from the drive shaft E .of the machine and as shown is mounted on a link 3 one end of which is bifurcated at 4 and has a pin and slot connection 5 with a crank 6 on a counter shaft 1 journaled in the bed plate of the machine. The other end of the link 3 is pivotally connected at 8 to a crank 9 on another counter shaft l journaled in the bed of the machine. The countershaft 1 is rotated alternately in opposite directions by a crank arm ll connected to the shaft and having a bifurcated end l2 in which rotates a cam 13 mounted on a secondary drive shaft l4 which is journaled in the bed of the machine and is driven by the usual crank and pitman connection l from the drive shaft E. With this construction, the counter shaft 1 is rotated alternately in opposite directions so as to vertically raise and lower the said dog I through the throat plate 2 into and out of engagement with the work.

For actuating the feed dog horizontally, the countershaft i0 is rotated alternately in opposite directions in accordance with the principles of my invention. As shown, the countershaft I ll has a pin ll projecting laterally therefrom through a slot H3 in the bed of the machine, the end of said pin being arranged in an opening IS in an actuating slide 20 so that the pin has a hinged or pivotal connection with the slide and reciprocation of the slide will cause rotationof the shaft alternately in opposite directions. The slide 20 is mounted on the bed of the machine in suitable guides 2|.

One end of the slide 20 has a pin and slot connection 22 with one end of a lever '23 which is pivotally mounted at 24 on a horizontal axis on a bracket 25 secured upon the top of the bed A of the machine. A follower roller 26 is journaled on a bracket 21 which is secured to the lever 23 by a screw and slotconnection 28, and the roller 26 cooperates with a cam G and is held in engagement therewith by a spring IIIA so that the cam oscillates the lever 23 to cause reciprocation of the slide 20, oscillation of the shaft I have shown a cam especially designed for making a long line of stitches wherein the stitches have many different lengths and spacing. As shown, the cam is in the form of a drum or cylinder and has a helical cam rib 23 in which cam segments or surfaces are formed. This cam is non-rotatably but longitudinally slidably mounted upon auxiliary shaft 30 that is journaled with its axis vertical in bearings 3| and 32, and has a worm gear 33 which meshes with a worm 34 on the drive shaft E. The cam G is moved longitudinally on the shaft 30 or in a direction parallel to the axis of the helical cam surface at a rate corresponding to the lead of the helical rib 29 so as to cause the convolutions of the rib to pass successively in contact with the roller 26.

For so longitudinally moving the cam during its cooperation with the follower roller 26 I have shown a screw 34 at the upper end of the shaft 30 which corresponds in pitch with the helical rib 29, said screw cooperating with a nut H-which is formed of two complemental sections 35 mounted for relative lateral movement into and out of engagement with the screw. As shown, the two sections of the nut are mounted in horizontal guideways 36 in a guide block 31 which is in turn slidably mounted for vertical movement or' in the same direction as the nut, in guideways 38' in a. bracket 39 fixedly mounted on the goose neck Got the machine.

For moving the two nut sections into and v out of engagement with the screw, each nut section is provided with a pin 40 extending into a. cam slot 4| in an operating disc 42 which is journaled on a stub shaft 43 in the guide block 31. The cam slots 4| are so related to each other and the disc 42 that upon rotation of the disc in one direction as shown in Figure 10, the nut sections are slid together into engagement with the screw 34, while when the disc 42 is rotated in the other-direction, the nut sections are disengaged from the screw. A suitable handle 44 is provided for rotating the disc 42.

Each nut section carries an arm 35!! which has a stud 35l slidably arranged in an annular groove 352 in an extension of the cam G, so that the cam may rotate relatively to the studs 35L but must move longitudinally of the shaft 30 with the nut sections.

. With this construction, it will be observed that when the nut sections are engaged with the screw and the shaft 30 is rotated by the worm 34 and gear 33, the nut will be elevated on the screw and will raise the cam G, the movements of the nut and cam corresponding to each other so that the cam rib 23 is moved with a screw action in engagement with the follower roller 26. This operation will normally be continued until the end of the cam rib 29 has reached the roller 26, whereupon the machine may be stopped, the nut sections disengaged from the screw, and the cam and nut sections allowed to slide downwardly to their initial positions shown in Figure 4.

As above stated the helical cam and rib 29 has cam surfaces so thatupon rotation of the cam the lever 23 will be oscillated about its pivot to reciprocate the actuating slide 20 and rotate the countershaft l0 so as to actuate the feed dog I horizontally and vary the operation thereof, for example reverse the direction of movement or interrupt or vary the extent of the movement at predetermined intervals, to feed the work through the stitch forming mechanism to-form a continuous line of stitches; The shape and arrangement of the cam surfaces may be varied in accordance with the character of stitching desired, but for the purpose of illustrating the principles of the invention I have shown the cam as designed for forming a line of stitches at the edge of a corset which has a clasp steel and hooks connected thereto. In Figure 57 I have illustrated a section of such a corset which includes two pieces of material H and I that are arranged in superposed relation as shown in Figure 58 and stitched together with a continuous line of stitches S shown in Figure 60. Between the two pieces of fabric H and I is arranged a corset clasp K which has clasps L secured thereto and projecting through gaps in the seam between the two pieces of fabric as shown in Figures 57 and 59. Also, a plurality of hooks M are secured between the pieces of fabric and project beyond the seam. The clasps L and hooks M are definitely spaced longitudinally of the edges of the garment, and the gaps through which the clasps and hooks project are formed by skip stitches or elongated stitches. Also, a group of superposed stitches is formed at the ends of the gaps. Referring to Figure 60 for conv enience and clearness in illustration and description, I have shown the line of stitches as comprising a plurality of series AA, BB, CC, EE, FF, GG, HH, and II, each series including a plurality of single stitches at least one group of superposed stitches and an elongate or skip stitch. In Figure 60, the first series AA of stitches includes eleven single stitches designated a, a group of superposed stitches b and a skip or elongated stitch c. While the next series BB begins with an elongated stitch c a group of stitches b which are followed by a series of single stitches a. The two elongated or skip stitches 0 form a gap through which projects the first clasp L of the clasp steel while the group stitches b serve as reenforcing stitches at the ends of thegap. The other series of stitches are similar in character, there being a gap for each clasp L and hook M with reenforcing stitches at the ends of the gaps and single stitches between each two adjacent gaps.

The helical cam rib 29 is provided with a plurality of cam segments clearly shown in Figures 61 to 61C inclusive, which are arranged in a plurality of difierent successive series so that the cam will cause formation of different series of stitches, or series having stitches of different character, length or spacing, upon successive revolutions of the cam. All cam segments for forming the stitches a are of the same form and designamd 45, and these stitches are formed upon forward movement of the woflr. This cam segment includes a dwell 45A and two

inclined surfaces

45B and 450. In beginning the sewing operation to form the line of stitches, the cam G is located at its lower position as shown in Figure 4 with the roller 26 in engagement with the first convolution of the cam; and the roller is located on the dwell 45A of one of the cam segments 45, or a corresponding dwell on another segment like segment 450. When the machine is started. the feed dog I is at the begimiing of its horizontal work feed stroke and retracted from the work N as shown in Figure 18. As the cam begins to rotate, the cam surface 45B rides under the roller 26 was to actuate the slide 20 toward the back of the machine, and slightly before the dog is raised by oscillation of the shaft 1 to bring the dog into engagement with the work as shown in Figure 15, so that the" work is fed forwardly the length of one stitch as shown in Figure 16. The dwell 45D then rides under the roller to hold the dog against horizontal movement while the needle penetrates the work, and simultaneously the feed dog is lowered away from the work as shown in Figure 17, whereupon the roller engages the inclined surface 45C to cause the dog to be moved horizontally forwardly to its initial position shown in Figure 18. When the roller reaches the dwell 45A the dog is held against horizontal movement in the position shown in Figure 18 while the dog is raised into engagement with the work as shown in Figure 15. This operation is repeated successively for each stitch at, these stitches being formed upon forward movement of the work through the stitch forming mechanism, that is, in the direction away from the operator or front of the machine. The first of the group stitches b is formed by a cam segment 46 which has an inclined surface 46A in continuation with the dwell 45A of the next preceding segment 45. As the roller 26 rides the dwell 45A the feed dog is elevated into engagement with the work at the beginning of the forward work advancing movement as shown in Figure 15, and the movement of the roller over the inclined surface 46A.a.dvances the work into the position shown in Figures 16 and 26 to form the first stitch 1). While the needle penetrates the work the dog is held against horizontal movement by the dwell 46B and the dog is simultaneously lowered away from the work as shown in Figure 19. The dwell 46B is longer than the dwell 45A and accordingly the dog is held in the position shown in Figure 17 at the end of the forward work advancing movement until the dog has been again raised in the same horizontal position, as shown in Figure 20. The roller then engages the inclined surface 41A of segment 41 which causes the dog to move the work backwardly as shown in Figure 21 to form the secother cam segment 45 to form the third group stitch b, see Figure 30.

After the last of the group stitches has been formed, the roller rides successively over the identical cam segments 48 to form two elongated or slip stitches c. Figures 32 to 35 illustrate the formation of one of these stitches. The operation of the work feed mechanism by these segments is the same as by the segments 45 but it will be noted that the projections 48 are higher than the segments 45 which causes the stitches c to be longer than the stitches a. The slip stitches may be completed stitches and broken prior to insertion of the claws 59 through the gaps, or they may be actually incomplete stitches; for example, the hook of the shuttle mechanism may be thrown out of normal timed relation with the needle so that the needle thread will not be caught by the shuttle hook as the needle penetrates the work at the end of the first stitch c, or suitable mechanism may be employed for pulling the needle thread to prevent the formation of a loop to be engaged by the shuttle hook, or a laterally vibrating needle maybe used and automatically thrown beyond reach of the shuttle hook. Also, the gap may be formed by a single longer stitch by simply making the segment 48 higher.

At the end of the slip stitch another group of stitches b is formed by additional segments 46,

5 whereupon a succession of stitches a are produced by additional segments 45. Figures 61A, 61B and 610 show the arrangement of the various cam segments corresponding to the stitches shown in Figure 60and further description is there- 10 fore believed to be unnecessary since the cam consists simply in the proper relative arrangement of cam segments of the same nature as those already described. Figures 61A to, 61C inclusive also show the relative horizontal positions of 15 the feed dog effected by the corresponding cam segments.

' As shown the height of the cam sections determines the length of the stitches and gaps, while the inclined surfaces determine the direction of 20 movement of the feed dog and the dwells hold the :lfeed dog horizontally stationary. While I have shown the gaps and slip stitches of the same length, obviously, the cam sections may be modifled to make different gaps of different lengths,

25 for example, to make a long gap for the hook W and a short gap for the hook X in Figure 64.

Figures 23 to 42 inclusive schematically illustrate the work and the formation of the various stitches therein, the needle being designated by 3 the reference character 0.

While the cam rib 29 may be formed continuously of one piece of material, it is preferable to form the rib of a pluralityof segments as shown in Figures 12 and 13, each segment comprising one'of the segments shown in Figure 61 and the segments being secured in a, helical groove 49' by screws 490. With such a construction, the

form of cam surfaces can be easily and quickly modified to suit different stitching requirements.

40 Where frequent changes in the cam are not necessary it may be. as desirable to form the cam segments on a flexible wire and wrap the wire he1- ically around the drum.

It will also be clear to those skilled in the art 45 that the helical grooves between the cam rib may be formed with cam surfaces to operate other parts of the same or a different machine, for example, to laterally vibrate the needle of the machine, especially where it is desired to form a slip 5 stitch by throwing the needle out of reach of the shuttle hook as before described.

Due to the necessity for extremely accurate spacingand the formation of the various stitches, and further due to the fact that the resistance to 55 movement of the work through the machine might causes1ippage-'betweenthe work and. the

I feed dog were not other means provided to prevent this, it is desirable to supplement the feed dog and its operating mechanism with an auxeoiiliary work advancing mechanism. As I have hereinbefore stated, it is desirable to avoid complications which would arise should it be attempted to'operate the auxiliary mechanism synchronously step by step with the feed dog, and 65 therefore I have shown a pair of continuously rotated

serrated rollers

50 and 5|, one of which is mounted on a shaft 52 in the frame of the machine. This shaft is driven by a spiral gear connection 520 with a countershaft 53 journaled 70 on the bed plate and having a spiral gear connection 54 with the shaft 30. The other roller 5| is mounted on a stub shaft 55 which is journaled in a frame 56 pivoted at 51 so that the roller 5| may move toward and from the roller 75 50. A' compression spring 58 normally presses the roller together. The roller 5| is also positively driven by a gear connection 560 with the shaft 52. The work is positively gripped between the two

rollers

50 and 5| and is continuously advanced by the rollers to the work feed dog I. It will be observed that due to the continuous feed of the work by the rollers 5|] and 5|, when the direction of movement of the work is reversed during formation of the group stitches b, slack will be formed between the rollers and the needle 0 as shown in Figures 43 to 56 inclusive. For example, Figure 43 shows the work taut between the rollers and the needle in position to begin the formation of the first group stitch b, while Figure 44 shows the completion of the first group stitch. Thereupon the direction of movement of the work is reversed to form the second group stitch as shown in Figure 45 which causes a slack in the work indicated at 59. The direction of movement of work is then again reversed to form the third group stitch as shown in Figure 46. In the present instance, the slack formed during making of the stitches b is utilized in forming the gaps, and after the group stitches b have been. completed the slip stitches c are formed as indicated in Figures 47 to 49 inclusive. The ratio between the gearing driving the

rollers

50 and 5| and the gearing driving the cam G is such, and the cam segments and connections be tween the lever 23 and the feed dog are so formed, that the slack produced during the formation of the group stitches is absorbed or taken up during the formation of the slip stitches as shown in Figures 45 to 49 inclusive, and more specifically described hereinafter. After formation of the slip stitches 0, another group of stitches b is formed as shown in Figures 50 to 52 inclusive, which causes another slack 60 in the work between the needle and the rollers. This slack is taken up or absorbed during the formation of the succeeding single stitches a so that the slack produced during the formation of the various group stitches is taken up by movement of the work after each group is completed so that there shall be no slack at the time the formation of the group stitches or gaps is begun.

- been completed, and there is slack in the work.

The feed-dog operating mechanism including the ections of the cam G is so timed, that it is apable of feeding the work during the formation of each' of the slip stitches c, a distance greater than one half of the combined length of the desired gap and the slack. Therefore, should the feed dog advance the work to its full capacity upon the formation of the first slip stitch 'c as is probable, then upon formation of the second slip stitch the feed dog will at first advance the remaining amount of work supplied by the

feed rollers

50 and 5|, and the work then being held by the rollers against further advance, the feed dog will slip on the work for the remainder of its work feeding movement. During return movement of the feed dog, the rollers will continue supplying the work for the next stitch of the next group of stitches b at the other end'of the gap.

The slack produced during formation of this second group of stitches is taken up in a similar manner, the parts of the feed dog operating mechanism including the cam sections 45, being so related that the feed dog is capable of feeding an amount of work for each stitch so that the total feeding capacity for the given number 10 of single stitches a is greater than the desired distance to be covered by said stitches plus said slack. For example, assuming the distance to be covered to be two inches, that there are to be sixteen stitches each approximately one-eighth of an inch in length, and there is about oneeighth of an inch slack, then the feed dog operating mechanism may be made to have a maximum capacity of feeding about eleven sixtyfourths of an inch for each stitch. Under these conditions the slack would be taken up during the formation of some of the stitches While the feed dog may slip a small amount for each of other stitches, and slight inaccuracies or lost motion in feeding will be compensated. In this way the gaps can be accurately located, over-- feeding being prevented by holding back of the work by the

rollers

50 and 5| and underfeeding being prevented by the excess feeding capacity of the feed dog mechanism.

With this construction, the major portion of the strain incident to advancing the work is taken up by the

rollers

50 and 5|, and exactly the correct amount of work to receive the stitches is supplied to. the needle by the rollers. The possibility of slippage of the work is thereby practically eliminated, and the work feed dog in conjunction with the cam G and the connecting mechanism, feed the work with precision to produce the proper character, length and spacing of the stitches and location of the gaps.

Also, instead of forming single stitches a as described, the cam rib 29 and cooperating parts may be readily changed to change the direction of feed of the work at proper intervals to form a line of groups of superposed stitches, each group including any desired number of stitches, for example as shown in my aforesaid copending application Serial No. 736,806.

Furthermore, instead of rotating and longitudinally moving the cam G relative to the roller 26, the cam might be rotatable but immovable in thevdirection of its axis, with the roller movable in' a direction parallel to the axis of the helical cam rib to maintain the roller in contact .with the successive convolutions of the helical cam rib 29.

Also, while the cam G has been shown and described as being returned to its starting position by manual release of the nut sections 35, it

will of course be understood that this operation might be accomplished automatically. Furthermore to avoid possibility of throwing out of adjustment of the parts through failure of the operator to stop the machine at the proper time, a pair of spring contacts 6| and 62 may be provided on the bracket 39 adjacent the upper end of the movementof the guide block 31, these contacts being normally in engagement to close a circuit through mechanism for stopping the machine upon opening of the contacts. 64 may be mounted on the guide block 31 to disengage the contact BI and 62 when the cam G has been raised to the upper limit of its movement,

75 While I have shown and described the inven- An actuating arm tion as embodied in certain details of construction and as used in a certain. form of sewing machine, it should be understood that this is primarily for the purpose of illustrating the principles of the invention. The invention may be used in connection with other typesof sewing machines, and the cam mechanism may be used for operating other parts than the feed dog of a sewing machine.

Having thus described my invention, what I claim is:

1. A sewing machine comprising a stitch forming mechanism, means for advancing work positively and continuously in one direction toward said stitch forming mechanism at a predetermined rate, and means for feeding work from said advancing means through said stitch forming mechanism in each of different directions including automatic means for reversing the direction of work feeding movement of said work feeding means at predetermined intervals to produce groups of superposed stitches in predetermined spaced relation, the steps of movement of the work feeding means in one direction compensating the slack produced in the work between said work advancing means and said work feeding means during the movements of the work in the other direction.

2. A sewing machine comprising a stitch forming mechanism, means for advancing work positively and continuously in one direction toward said stitch forming mechanism at a predetermined rate, and means for feeding work from saidadvancing means through said stitch forming mechanism in each of different directions including automatic means for reversing the direction of work feeding movement of said work feeding -means at predetermined intervals, the steps of movement of the work feeding means in one direction compensating the slack produced in the work between said work advancing means and said work feeding means during the movements of the work in the other direction.

3. A sewing machine comprising a stitch forming mechanism, means for advancing work positively and continuously in one direction toward 'said stitch forming mechanism at a predetermined rate, and means for feeding work from said advancing means through said stitch forming mechanism in each of different directions including automatic means for reversing the direction of work feeding movement of said work feeding means at predetermined intervals to produce a plurality of pairs of a group of superposed stitches and form a slack in the work between said work advancing means and said work feeding means during the formation of each group, and means for varying the extent of movement of the work feeding means at predetermined intervals to change the rate of movement of the work between the groups of each pair of groups of stitches and take up said slack.

4. A sewing machifi comprising a stitch forming mechanism, means for advancing work positively and continuously in one direction toward said stitch forming mechanism at a predetermined rate, and means for feeding work from said advancing means through said stitch forming mechanism ineach of different directions including automatic means for reversing the direction of work feeding movement of said work feeding means at predetermined intervals to produce, a plurality of groups of superposed stitches and form a slack in the work between said work advancing means and said work feeding means during the formation of each group, and means for varying the extent of movement of the work feeding means at predetermined intervals after the formation of each group of stitches to vary the rate of movement of the work and take up said slack.

5. A sewing machine comprising a stitch forming mechanism, and work feeding means including a device for gripping the work, a cam having a helical cam portion, a follower for said cam portion, an operative connection between said follower and said work gripping device for actuating the latter, and means for causing engagement of said follower with said helical cam surface throughout the length of said surface, said cam portion having different successive series of cam surfaces to cause production of different series of stitches upon successive revolutions of the cam.

6. A sewing machine comprising a stitch forming mechanism and work feeding means including a device for gripping the work, a rotatable and longitudinally movable cam having a helical cam surface, a follower for said cam surface immovable in a direction parallel to the axis of the helical cam surface, an operative connection between said follower and said work gripping device to actuate the latter, and means for simultaneously rotating and longitudinally moving said cam to cause engagement of said helical cam surface with said follower throughout the length of said helical surface.

7. A sewing machine comprising a stitch forming mechanism and work feeding means including a device for gripping the work, a rotatable cam having a helical camsurface, a follower for said cam surface, an operative connection between said follower and said work gripping device to actuate the latter, and means for simultaneously rotating said cam producing relative movement of said cam and follower in a direction parallel to the axis of the helical cam surface to cause said follower to engage said helical cam surface throughout the length of said surface.

8. A sewing machine comprising a stitch forming mechanism and work feeding means including a device for gripping the work, a rotatable and longitudinally movable cam having a helical cam surface, a follower for said cam surface immovable in a direction parallel to the axis of the helical cam surface, an operative connection between said folower and said work gripping device to actuate the latter, a rotatable screw, a non-rotatable nut on said screw mounted for longitudinal movement on said screw, an operative connection between said cam and said nut to cause longitudisurface, a follower for said cam surface immovable in a direction parallel to the axis of the helical cam surface, an operative connection between said follower and said work gripping device to actuate the latter, a rotatable shaft on which said cam is non-rotatable but longitudinally movable, a screw on said shaft, a nut engaging said screw and held against rotation but free for longitudinal movement on said screw, an operative connection between said nut and said cam for longitudinally moving the cam with said nut, and

means for rotating said shaft, so as to cause said helical cam surface to engage said follower throughout the length of said cam surface.

10. The machine set forth in claim with the addition of means for disengaging said nut from said screw to permit free longitudinal movement of the cam in the opposite direction.

11. The machine "set forth in claim 16 with the addition of means for disengaging said nut from said screw to permit free longitudinal movement of the cam in the opposite direction.

12. A sewing machine comprising stitch forming mechanism, means for feeding work step-bystep through said stitch forming mechanism including a feed dog, a rotatable cam having a peripheral cam surface of a length several times greater than the length of the periphery of the cam in a plane perpendicular to the axis of the cam and formed with a cam portion to govern feeding of the work for each stitch, and a follower for the cam surface operatively connected to said feed dog.

13. A sewing machine comprising stitch forming mechanism, means for feeding work step-bystep through said stitch forming mechanism including a feed dog, a rotatable cam having a peripheral cam surface of a length several times greater than the length of the cam in a plan perpendicular to the axis of the cam and formed with a cam portion to govern feeding of the work for each stitch, a follower for the cam surface operatively connected to said feed dog to engage said cam surface from one end thereof to the other, and means for relatively moving the follower and said cam surface in a direction parallel to the axis of the cam from engagement at any intermediate point of the cam surface into engagement at a point of said cam surface in advance of said intermediate point. I 14. A sewing machine comprising a stitch form ing mechanism, and work feeding means including a device for gripping the work, a rotatable cam and a follower therefor, said cam having a plurality of coaxial sections forming together a cam surface of a length several times greater than the length of the periphery, of the cam in a plane perpendicular to the axis of the cam and having a series of cam surfaces brought into contact with said follower upon successive revolutions of said cam, means connecting the follower to said work gripping device to operate the latter, and means for causing engagement of said follower successively with said coaxial sections.

15. The combination with a sewing machine including a stitch forming mechanism and work feed means, of a cam operated mechanism operating in timed relation to said stitch forming mechanism and said work feed means for varying the character of stitching, said cam mechanism including a rotatable cam and a follower therefor, said cam having a cam portion of a length several times greater than the length of the periphery of the cam in a plane perpendicular to the axis of the cam and including successive series of cam surfaces of different size and shape whereby different variations in the character of stitching may be effected throughout a long line of stitches.

the work, a countershaft, an operative connection between said countershaft and said feed dog to move the latter horizontally in opposite directions upon rotation of said countershaft in opposite directions in timed relation to reciprocation of said needle to feed the work in one or the other of two opposite directions upon each work engaging horizontal movement of said feed dog, a cam driven by said drive shaft, a follower for said cam operatively connected to said countershaft to rotate the latter, said cam having a