US2407986A - Stitch length adjusting mechanism - Google Patents

Description

p 1946- c. w. JO'HNSON STITCH LENGTH ADJUSTING MECHANISM Original Filed Aug. 12, 1939 2 Sheeis-Sheet 1 CARL VV. JOHNSON ATTORNEY.

Sept. 24, 19 46. I JOH NSON 2,407,986 I STITCH LENGTH'ADJUSTING MECHWISM Original Filed Aug. 12, i939 2 Sheets-Shet 2 FIG. 5

FIG, 3

INVENTOR CARL W. JOHNSON ATTORNEY Patented Sept. 24, 1946 STITCH LENGTH ADJUSTING MECHANISM Carl W. Johnson, Brooklyn, N. Y., assignor to American Machine and Foundry Company, a corporation of New Jersey Original application August 12, 1939, Serial No.

Divided and this application August 11, 1942, Serial No. 454,353

This invention relates to sewing machines, and the present application is a divisional application from the earlier application, Serial No. 289,907, filed August 12, 1939, for Sewing machine and relates to improvements in mechanism for controlling the length of stitches to be formed during the operation of the machine.

The invention relates further to sewing machines, especially of the under and over stitch type, utilizing a double pointed needle having an eye located between the points, and has particular reference to mechanism for controlling the length of stitches formed by the movement of this type of needle and a thread through work being sewed.

In order to meet all of the demands which may be imposed upon my machine in sewing all of the various kinds of materials which may be handled thereon, it may be necessary from time to time or during the sewing of any particular work or material to change the length of the stitch from long to short or vice versa, or to utilize a certain length stitch for one part and another length stitch for another, etc. For that reason my invention further consists in the provision of improved mechanism which makes it possible to change the length of the stitch from time to time whenever necessary. This mechanism may operate automatically or be adjusted manually to change the length of the stitch whenever. desired.

It is a further object of my invention to provide improved mechanism for use with a machine employing a double pointed needle in which changes in stitch length are made automatically during the operation of the machine.

It is also an object of my invention to provide mechanism which automatically changes alternate stitch lengths during the operation of the machine.

It is also an object of my invention to provide a sewing machine of the type forming over and under stitches of a predetermined length, and selective means for changing from one length to another either manually or automatically.

With these and other objects'not specifically mentioned in view, the invention consists in certain' combinations and constructions which will be hereinafter fully described, and then specifically set forth in the claims hereunto appended.

In the accompanying drawings which form a Part of this specification, and wherein the several reference characters designate the same or like elements:

4 Claims. (01. 112-210) Figure 1 is a partial front elevation of the sewing machine embodying my improved stitch length controlling mechanism; t

Figure 2 is a detail View taken on line 22 of Figure 1 showing one form of the feeding.

in which it is possible to produce alternate short and long stitches automatically;

Figure 5 is an end view of Figure 4;

Figure 6 is a sectional partial side elevation of a detail of the work feeding mechanism taken on line 5-6 of Figure l; and v Figure 7 is a plan view of a detail of the stitch length adjusting mechanism shown in Figure. 3.

Referring to the drawings, Figure 1 shows a preferred embodiment of my invention adapted for use in a machine of the type employing a double pointed needle N having an eye between the points and needle bars 55, 56 provided with tapered caps 12 serving to confine spring pressed jaws (not shown), which may be of the type shown in Naftali Reissue Patent No. 19,653, granted July 23, 1935, which clutch the needle N, to perform the stitching. As shown, the machine comprises a stationary frame I ll, a.sew-.

ing machine head ll extending therefrom and a bracket I 2 supporting the work table 113. Hand wheel 4| is driven in the manner described in my .co-pending application to operate the needle bars and associated mechanism from a suitablemotor and clutch (not shown) by means of a pulley 24, driven by means of a belt 23 running on a pulley 22 carried by shaft 36 which mounts a pulley I9 over which runs a motor driven belt l8.

It will be understood by those skilled in the art, that in this type of machine, needle N is projected back and forth through the work and is, therefore, alternately grasped by the jaws of upper bar. The upper needle bar upon receiving t e needle from the lower needle bar 56, rises and elevates head 13 from engagement with lug 63. At the moment this occurs, the spring pressed jaws clutch the needle by reason of the spring action in needle bar 55, and movement of the jaws into cap 12. The operation of the lower needle bar 56 is effected in the. same general. manner, and hence it will be understood that whenever a head 13 is not in engagement with a lug 63, the spring action in each needle bar will. force the gripping jaws into cap I2 and cause the jaws to grip the needle. The spring action of the jaws acts alternately so that-first one and then the other bar grips the needle. I

The work is fed over table I3 beneath a presser foot I provided to engage and retain it in sewing position. This foot is secured to a holder 76 clamped to the lower end of aspring' tensioned rod 1'! which is guided in the lugs 63 and 64 of member 65. The rod 11 is provided with a. block I8 fitting in the space between the rear wall of member 65 and. a. strap 79 secured to a portion of member I55 and in this manner tends to re.- tain the presser foot in alignment with the needle bars. The upper end of the rod TI is provided with a collar till-normally abutting a. forked block 81- fastened to one end of a pivot shaft, 82. One end of shaft '82 is mounted on a projecting. lug 83 of member 63' and has its other end mounted in a lug. (not shown) secured. to th wall 21 of head I.I... At a point along. the length of shaft 82' is mounted an actuator arm 8'6 carrying a stud supporting a head 87 which holds one end of. arod 88 connected to a link (not shown-)1 in turn. connected to 'a manually operated shift plate (not shown) all. as shown and described in my co-pending application,v Serial No. 289,907 in order to raise and lower foot I5. -By lifting the presser foot the operator may readily inspect the work or locate new work in sewing position.

When the lower needle bar 55 ascends, causing the. needle N. to push. the thread, through the- Work, thefsudden thfrust or piercing tends to overcome the spring pressure of rod 11 and lift the presser foot '15 from the work. It is desirable to have the spring 95 of rod I1. weak enough to allow the presser foot. to. yield upwardly in. order to allow the work. to be readily manipulated, and to prevent undue pressure on thework. In order'to. overcome any. excess upward movement thereof, a spring actuated arm 96 may be provided, which is in close relationship with the, upper end of' rod 11 so that the rod in moving upward will strike th end of the arm 96, and be forced. back, thereby tending to hold the presser foot in proper operative position relative to the work. Arm 96 is mounted on. a pivot stud (not shown) carried by a bar 98 suspended from head II and is urged by a spring (not shown) downwardly to hold an adjusting screw Illl in abutment with a suitable stop (not shown). The screw III! is provided sothat the. gapbetween rod IT and arm 96 may be varied to best; suit. conditions and. when. properly set the. screw is locked in position by any suitable, means, such as'a knurlednutI03'.

Referring to Figure 1, the mechanism for pulling the: loop as formed from the thread will now be. described briefly since it forms no part of this invention. A gear I75 meshing with th gear 4.4; but rotating at a greater speed. is fixed to. a shaft I16; mounted. in suitable bearings I IT of head l.iand of a stationary member or. drum I18, suitably supported by head II and frame I0; A gear through suitable driving connections shown and described in my co-pending applicato be described hereinafter.

tion, drives the thread puller I86 in order to pull the loose end of the thread through the work. The thread puller I86 is provided with a pointed thread engaging end so mounted that it may rotate around the periphery of the stationary drum member I18. The chief function of the. thread puller is to engage the loop of thread formed on alternate movements of the needle and pull the thread through the work, and dispose it about the periphery of the drum in such a manner that the. danger of snarling, fouling or breaking the. thread is practically eliminated. Thread, puller I is fixed to the outer end of a carrier arm. I81; which is pivotally mounted on a rotating member (not shown). The outer end of arm I8! is also provided with a curved guide plate,- =93 adapted to engage a tape I94 partly circling the drum I18, which tape acts to maintain the thread in orderly fashion and also prevents whipping of the thread as it is placed around the drum. A brush S may be fixed beneath the drum IIBi, as shown in Figure I, in

order to act as. a brake and apply a frictional; force upon the thread as itis. being pulled from.

the drum. This adds additional control in handling the thread and prevents it from whipping. about or tangling in any'manner.

The driven sprocket 4.2 (Figure 1) imparts motion to a chain I05 running over a sprocket. I06. mounted on a shaft I01 supported in a hub of bracket I08 secured toframe I6.. The opposite end of shaft I0! supports a coupling I09 (Figure- 2) terminating ina cam surface III] which imparts up and down motion. to the material feed.

Member I 09 supports a short eccentric. stud, I'I'I' equipped with a roller H2 engaging an elongated slot H3 provided. in the lower. end of lever I I4 fulcrumed on arm H5 which is mounted .on the end of a, pivot. stud H6 secured to frame ['0 by a bolt I'I'I, Lever H4 mounts a stud [I8 carrying a follower II9' engaging a slot I20 in th head. of a slotted member I2 I mounted in a counterbored portion [22. of plug 123 turnablysupported' in an. aperture of frame I0.

By loosening the thumb screw I26}. arm [24- maybe moved, and in so. doing shiftr the position.

of slot I20 in member I'ZI, thereby. changing the angular relation of' slot I20 and lever II4., Arm.

I24. is provided with an. arcuate slot. I25 in. order.

to allow said arm to be moved relative to loosened screw I26 in order to adjustthe position of member I20 and secure the slot, IZI' therein in any desired adjusted position relative to fol.- lower' H9.

rection so that the slot therein will be moved.

more towards'th'e horizontal. Sincel'ever H5 is fastened to a fork I 21 (Figure. 2) connected t a material feed arm I28", the resulting to. and fro motion imparted to arm I28 can be varied,

thereby making it. possible to adjust. the length. and make longer or shorter stitches as required.

The up and down movement of arm I28 imparted by a cam H0 with which coacts a camfollower I29 provided on an arm of lever I30 the lever supportsone end of an adjustablejlinln It will be apparent, therefore, that the more slot H0 is turned towards the vertical,.

I32 which is connected to a depending arm I33 of member I28. The right end of arm I28 (Figures 1 and 6) is mounted on a pivot stud I40 supported in lug I4I of an arm I42 loosely mounted on stud I34. ()ne end of this stud is mounted in a spacing block I43 suitably secured to frame I0.

Material feed plate I35, attached to arm I 28, is provided with a corrugated or toothed work feeding surface adapted to engage and advance the work. This plate may be of the usual type employed in sewing machines and is arranged to project upwardly through a slot in plate I3 over which the work is fed to and from the needle. IAS each stitch is completed, the arm I28 through its connections, is caused to index, that is, the arm descends slightly below the level of throat plate or table I3 leaving the work resting thereon and then the arm moves up, engages and advances the work in readiness for the next stitch, the work remaining in this position while the plate I35 returns to its original position.

Referring to the modification shown in Figure 3, the general operation of the feed arm I28 is the same as hereinabove described. Mechanism has been provided, however, to make adjustments in order to control the stitch length for normal stitching, and also make longer or shorter stitches as the case may be according to the requirements with respect to the particular work being sewed. As an example, in sewing the sides of the fingers of gloves, a normal stitch length is generally used for the major portions of each glove. However, when the operator proposes to sew the tip portion of the fingers, the normal stitch may be found to be too long for satisfactory work, and hence means is provided for quickly shortening the stitch length. At this time, the operator depresses a foot pedal 308 which through connections to be described presently, shifts the position of the slotted stitch contro1 member I2I to produce shorter stitches for sewing the finger tip portion of the glove. When the sewing of the tip portion is completed, the operators foot is released from the pedal and normal stitching will be resumed.

An arm 300 (Figure 3) is clamped to member I2I and at its lower end supports a forked head 30I and a head 302 connected by means of a rod 303 to an arm 304 fixed on a pivot shaft 305. An arm 306, also fixed on shaft 305, is actuated by a link 301 connected to a foot pedal 308 mounted on a pivot 309. The forked head 30I carries an adjustable link 3I0 which at its other end is provided with knurled nuts 3H and 3I2 which are turnably and slidably mounted in an aperture 3 I 3 of a holder 3I4 secured in a suitable manner to the frame of the machine. The aperture 3I3 is open at the top and exposes a portion of the shanks 3I5 of the nuts 3H and 3I2, the exposed portion of the shanks being engaged by prongs of a flat spring 3I6 which tend to hold said nuts from turning after the final adjustments have been made.

The knurled nut 3| I provides means for adjusting the position of member I2I to obtain the length of stitch best suited for different types of Work. A spring 3I'I having one end attached to arm 304 and its other end secured to a stationary part of the machine (not shown) normally tends to hold the shoulder 3I8 of nut 3 in engagement with holder 3I4. The knurled nut 3I2 governs the length of the short stitch. That is, with the foot pedal 308 depressed the rod 303 will move arm 300 and consequently change the position of member I2I by varying the throw of lever arm II 4 which controls the horizontal distance traveled by bar I28. The movement of arm 300 causes link 3I0 to remove the shoulder 3| 0 of nut 3II from holder SM and advance nut 3I2 until its shoulder 3I9 abuts the other end of holder 3 I4 thus halting further movement of arm 300. Member I2I retains this position until the foot pedal 300 is released, whereupon spring 3II restores the device to its former position. It will be apparent that the greater the distance between shoulder 3I9 and the end of the holder 3M, the greater will be the movement of arm 300 to set m mber I2I, which consequently results in shorter stitches.

Referring to Figures 4 and 5, another modified stitch control device is shown in which alternate short and long stitches are automatically produced for. decorative work. Accordin to this embodiment, a driven sprocket 320 fixed on a shaft 32I imparts motion to the eccentric III and cam IIO to actuate the material feed arm I28 in the same manner as shown in Figures 1, 2 and 3. A gear 322, fixed on shaft 32I, meshes with and drives a gear 323 and its attached gear 324 loosely mounted on stud IZIa, while the gear 324 in turn drives a gear 325 and a cam 326 loosely mounted on shaft 32I. In this manner, the gearin 322, 323, 324 and 325 drives the cam 326 at one-half the speed of cam IIO. Cam 326 engages a cam roller 32! carried by a cam lever 328 mountedon shaft I2I. Lever 328 is adjustably attached to an arm 329, clamped on shaft I2I by a thumb screw 330. The lower portion. of arm 329 is pro.- vided with an elongated slot 33I adapted to engage thumb screw 330. By loosening the thumb screw 330, the arm 329 may be moved and in so doing shift the position of slot I20 of shaft I2I resulting in more or less movement of arm I 28, as heretofore mentioned.

The cam 326 has a high portion 332 and a low portion 333, the surface 332 beingconsiderably longer than 333 and therefore when it engages follower 32'! it holds the slotted head of stitch control member I20 in a position to produce a 7 long stitch, as the follower 321 rides ofi surface 332 and approaches surface 333, the slotted head of member I20 is turned to a position to produce a short stitch. The continuous rocking of the slotted head results in alternate long and short stitching of the work.

In the mechanisms hereinabove described it will be evident that I have provided means for forming stitches of a predetermined length, and selective mechanism operative either manually or automatically to vary the stitch length by control of the work feeding device in accordance with the wishes of the machine operator or the demands of a given piece of work being sewed or decorated.

The invention above described may be varied in construction within the scope of the claims, for the particular device, selected to illustrate the invention, is but one of many possible concrete embodiments of the same. It is not, therefore, to be restricted to the precise details of the structure shown and described.

What is claimed is:

1. In a sewing machine, a work support, means for feeding work to be sewed along said support including a work feed bar, and mechanism. for varying the amount of movement of said means, said mechanism comprising a lever associated with said bar, a second lever pivoted on said first-named lever, means for oscillating said second lever, a follower carried by said second lever, a slotted member normally engaging said follower, anadjusting rod secured to said member, adjusting means connected to said rod for setting the length of stitch to be made at a predetermined length, a manually operated device attached to said member for shifting said member to change the stitch from one length to another at the will of the operator while maintaining the adjustment of said adjusting means undisturbed, and means for automatically moving said device in the opposite direction to reset said memher in its original adjusted position.

1 '2. In a sewing machine, the combination with a work support, of mechanism for feeding work to be sewed along said support, means associated with said mechanism for adjusting the length of stitch to be made, said means including a stitch length control member, means for setting said member to form stitches of various lengths, an armfixed to said member, an adjusting rod, a connection between said arm and one end of said rod, a holder supporting the other end of said rod, adjusting nuts on said holder supported end of said rod, said nuts being located on said rod at opposite sides of said holder, means for securing said nuts in adjusted position on said rod and relative to said holder, one of said nuts being adjustably positioned on said rod to control the position of said member for forming a predetermined normal stitch length, means normally holdin'g said nut in engagement with said holder, and manually operated means for moving said member'to displace said rod and said one of said nuts from said holder and cause said other of saidnuts to engage said holder whereby to modify the movement of said feeding mechanism and thereby control the length of stitch formed. l

3. In a sewing machine, a work support, means for feeding work to be sewed along said support 8 including a workfeed bar, and mechanism for varying the amount of movement of said means, said mechanism comprising a lever associated with said bar, a second lever pivoted on said first-named lever, means for oscillating said second lever, a follower carried by said second lever, a slotted member normally engaging said follower, means for shifting the position of said slotted member to vary the extent of movement of said lever and travel of said feeding means, and

a manually adjustable device connected to said member for setting the stitch length within predetermined limits, said device including a rod attached to said member, a block slidably mounting one end of said rod and adjustable nuts mounted on said rod at opposite ends of said block.

4 In a sewing machine, a work support, means for feeding work to be sewed along said support including a work feed bar, and mechanism for varying the amount of movement of said means, said mechanism comprising a lever associated with said bar, a second lever pivoted on said first-named lever, means for oscillating said second lever, a follower carried by said second lever, a slotted member normally engaging said follower, means for shifting the position of said slotted member to vary the extent of movement of said lever and travel of said feeding means, a manuallyadjustable device connected to'said member for setting the stitch length within pre- 7 determined limits, said device including a rod attached to said member, a blockslidably mounting one end of said rod and adjusting screws mounted on said rod at opposite ends of said block, a second rod also attached to said member, and manually operated means operative at will for moving said second rod and shift the position of said member for changing the stitch length within said set limits.

CARL W. JOHNSON.

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