US2063844A - Attachment for sewing machines - Google Patents

Description

Dec, 8, 1936.y f J. D. KARLE 2,063,844

I ATTACHMENT FOR SEWING MACHINES Filed Dec. 2o, 1934 2 sheets-sheet 1 3mm/m Joh/xn D; Karle Dec. 8, 1936.

J. D. KARLE ATTACHMENT FOR SEWING MACHINES Filed neg. 2o, 19574 John I7. Earle 2 Sheecs-Sheerl 2 Patented Dec. 8, 1936 UNE STATS slr.

ATTACHMENT FQR SEWHNG MACHINES Application December 20, 1934, Serial No. '758,331

6 Claims.

This invention relates to attachments for sewing machines and more particularly to attachments for vibrating the work relative to the needle and laterally of the line of seam formation to produce zigzag stitches The several features of the present invention will be clearly understood from the following description and accompanying drawings in which:

Figure 1 is a front elevation showing a portion of a sewing machine with my improved attachment fixed thereto.

Figure 2 is a rear elevation.

Figure 3 is a side elevation looking from the right of Figure 1.

Figure 4 is a top plan view.

Figure 5 is a disassembled perspective view of the pawl and two-part needle-bar actuated lever.

My improved attachment is shown applied to a well known Singer family type machine having the usual spring-pressed presser-bar reciprocating needle-bar 2, needle-clamp 3, needle li, and feed-dog 5.

In its preferred embodiment the attachment comprises a channel block 6 adapted to be secured by the fastening screw 'i to the lower portion of the presser-bar i. Carried by the block 6 is a plate 3 having an upstanding inclined arm 8 and a cross arm 9 formed with elongated apertures i l) and outwardly projecting lips which form a guiding channel. Slidably held in the guiding channel by the rivets l2 is a bar I3 having a depending portion lll to which is secured by means of the screw l5 a presser-foot iii formed with an elongated needle-aperture l5.

Pivotally secured to the upstanding arm 8 of the piate 8 by the pivotpin 'l is a swingable member |13 having a laterally extending portion i9 provided with a stud I9. The swinging member i3 has an opening 23 with inwardly extending projections 25 and E5 adapted to embrace and engage a cam element 26 having a plurality of circumferentially `spaced projections. Fixed to the cam-element 26 is a ratchet-wheel 28, and the cam-element and ratchet-wheel are rotatably mounted on the lplate i! by means of a bearing pin 2S.

Pivotally secured to the arm 8 by the pivotpin 30 is a lever 3| (Fig. 5) formed with an apertured free end 32, a forwardly extending arm 33 and a rearwardly extending arm Sli. A lever 35 having a forwardly extending lip 33 and a rearwardly extending portion 3l is pivotally secured to the end 32 of the lever 3| by the internally threaded pivot-stud 33 on the pawl 39 (Fig. 5). It will be understood that the stud 3S passes (el. i12- 160) through the aperture 4i! in the lever 35 and the aperture lit in the lever 3| and is held in position by the screw di. A helically wound spring i2 reacts between the arm 33 on the lever 3| and the pawl 39 to constantly urge the pawl in a v5 clockwise direction about its pivot-stud 38.

A spring i3 embraces the spacing sleeve 44 and has one of its ends acting against the arm 8 and its other end against the portion 31 of the lever 35. The spring i3 urges the lever 35 in a clockwise 10 direction about its pivot, the movements being limited by the nose on the lever 35 which engages the rearwardly extending arm 34 on the lever 3|. The spring 43 also urges the levers 3| and 35 and the pawl 39 in a counter-clockwise 15 direction about the pivot-pin 30, this movement being limited by the arm 3&3 which engages the arm 8. From the foregoing it will be observed that the levers 3| and 35 are in effect a two-part pawl-carrying lever. '20

A nger-lever lili is provided for rendering the attachment inactive at the will of the operator. This expedient is shown and described in Patent No. 2,003,200, dated May 28, i935.

Made integral with the cross-arm 9 is an upstanding arm il having a bell-crank lever 48 pivotally secured to its upper end by the pivot-pin 49. One arm of the bell-crank lever is bifurcated to receive the stud I9 carried by the swingable member I8 and the other arm is formed with an arcuate slot 50. A pitman 5| connects the bellcrank lever 43 to the slide-plate i3 and has one of its ends adjustably secured in the slot 50 by the screw 52 and its other end pivotally secured by the pivot-pin 53 to the slide-plate |3.

Operation On the upward movement of the needle-bar, the needle-clamp 3 engages the projection 36 on the lever 35 and moves the lever 3| and pawl 39 upwardly. During the movement the pawl 39 engages the ratchet-wheel 28 and advances it one step or one-eighth of a revolution, it being understood that the distance the pawl travels on each upstroke of the needle-bar is slightly greater than the distance between the teeth on the ratchet-wheel. The cam-element 26 being fixed to the ratchet-wheel 28 is also moved one-eighth of a revolution. The rotation of the cam-element causes one of its circumferentially spaced projec- 50 tions to Contact the inwardly extending projections 25 on the swinging member I8 causing it to swing in a clockwise direction about its pivot il. This swinging movement causes the pin I9 to swing the bell-crank lever 48 in a counter-clock- 55 Wise direction about its pivot 49. This motion is imparted to the slide-plate I3 by means of the pitman 5I thereby causing the presser-foot I6 to move to the left to the position shown in Fig. 1. The shifting of the presser-foot I6 occurs while the usual feed-dog 5 is below the throat-plate 55 and is completed just prior to the point of the cycle when the feed-dog contacts the work. After the feed-dog 5 has advanced the work, the needle descends, forming the stitch and on the upstroke of the needle, the needle-clamp 3 again engages the forwardly extending portion 36 of the lever 35 and moves the lever 3I and pawl 39 in a counter-clockwise direction about the pivot 30, the pawl again advancing the ratchet-wheel oneeighth of a revolution. This movement of the ratchet-wheel causes the cam 26 to shift the swingable member I8 in a counter-clockwise direction about its pivot and this movement is irnparted to the slide-plate I3 by means of the pin I9', bell-crank lever 48 and pitman 5I. The slideplate I3 and presser-foot I6 are thereby shifted to the right. From the foregoing it will be observed that in the rotation of the cam-element 26, its peripheral projections successively engage the projections of the swinging lever I8 to vibrate the same and thus reciprocate the slide-plate and presser-foot laterally of the line of seam formation. It will be obvious that the amount of movement of the slide-plate I3 may be varied by adjusting one end of the pitman 5I in the arcuate slot 50 of the bell-crank lever 48.

This construction provides an adjustment for varying the lateral shifting movement imparted to the presser-foot which can be quickly and easily made and translates the arcuate movement of the pin I9 to a right line movement without using a lost motion connection between the swinging member I8 and sliding plate I3, thereby reducing the operating noise of the attachment by eliminating the hammer blow. Further, overthrow of the presser-foot under speed is prevented.

It has been found that when an attachment of this type is fixed to the presser-bar with the needle-bar clamp in its highest position, the lip 36 on the pawl-carrying lever is disposed beneath the needle-clamp with the result that, upon operation of the machine, the needle-clamp on its down stroke will strike the lip 3S and damage the attachment. To overcome this diiculty, the pawl-carrying lever is made in two parts (3| and 35) which are pivoted together and the lever 35, which is engaged by the needle-bar clamp, is spring-urged about its pivot in a clockwise direction by the spring 43 and its movement is limited by the stop 45 and arm 34.

With this arrangement, if the attachment is inadvertently attached to the machine with the end of the pawl-carrying lever in a position toy be engaged by the needle-clamp on its downward stroke, upon operation of the machine the free end of the lever 35 will yield to permit the initially descending needle-clamp to pass. After the needle-clamp has passed, the lever will assume its operative position due to the influence of the spring 43.

Having thus set forth the nature of the invention, what I claim herein is:-

1. A zigzag-stitching attachment comprising a. member adapted to be secured to the presserbar of a sewing machine, a frame carried by said member, a slide-plate carried by said frame, a swingable member carried by said frame, a cam for vibrating said member, ratchet and pawl means for actuating said cam, a bell-crank lever pivoted to said frame and actuated by said swingable member and means for connecting said bellcrank lever to said slide-plate.

2. A zigzag-stitching attachment comprising a member adapted to be secured to the presser-bar of a sewing-machine, a frame carried by said member, a slide-plate carried by said frame, a swingable member pivoted to said frame, a cam for vibrating said member, ratchet and pawl means for actuating said cam, a bell-crank lever pivoted to said frame and actuated by said swingable member and a pitman having one of its ends adjustably connected to one of the arms of said bell-crank lever and its other end pivotally connected to said slide-plate.

3. A zigzag-stitching attachment comprising a member adapted to be secured to the presserbar of a sewing machine, a frame having an upstanding arm and a cross-arm formed with a channel secured to said member, a slide-bar carrying a presser-foot tted in said channel, a swinging lever fulcrumed on the upstanding arm of said frame, a cam pivoted to the upstanding arm of said frame for actuating said swinging lever, means for actuating said cam, an upstanding arm carried by the cross-arm of said frame, a bell-crank lever pivoted to said arm and having one of its arms operatively connected to said swinging lever and a pitman connecting said slide-bar to the other arm of said bell-crank lever.

4. An attachment for sewing machines having a vibratory work-engaging member and means for vibrating said member, said means including a cam, and a ratchet and pawl for actuating said cam, said pawl being carried by a two part pivoted lever composed of relatively yielding parts.

5. In combination with a sewing machine having a needle-bar and a presser-bar, a frame secured to said presser-bar, a slide-plate carrying a presser-foot mounted on said frame, a swingable member pivoted to said frame, a cam for actuating said member, and means for actuating said cam, said means comprising a ratchet fixed to said cam, a lever pivoted to` said frame, a second lever pivoted to the first mentioned lever and having a stop to limit its movement in one direction relative to the first mentioned lever, a spring for yieldingly urging said second lever against said stop, and a pawl carried by said lever for actuating said ratchet-wheel.

6. An attachment comprising a frame adapted to be secured to the presser-bar of a sewing machine, a slide-plate and presser-foot carried by said frame, a swingable member pivoted to said frame, a bell-crank lever actuated by said swingable member, a connection between the bell-crank lever and said slide-plate, a cam in operative engagement with said swingable member, a ratchet-wheel carried by said cam, a needle-bar actuated two-part lever pivoted to said frame and having a yieldable free end and a pawl carried by said lever for imparting a step-by-step movement to said ratchet-wheel.

JOHN D. KARLE.

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