US2121884A - Sewing machine - Google Patents

Description

v June 28, 1938. E. PRAzAK `2,121,884

SEWING MACHINE Original Filed July 13, 1935 2 Sheets-Sheet 1 1 I 'mmm INVENTOR zam-f 7% 6%, BY

E. PRAZAK l 2,121,884

`lune 28, 1938.

` SEWING MACHINE l original Filed July 15, 1935 2 sheets-sheet 2 ATTORNEY.

Patented June 28, 1938 UNITED vSTATES SEWING MACHINE Emil Prazak, Elizabeth, N. J.

`Substitute for application Serial No. 680,166, July 13, 1933. This application December 3,

1935, Serial No. 52,653

2 Claims.

This invention relates to improvements in sewing machines adapted to effect in operation predetermined pattern stitching; this application being a substitute for applicants prior application Serial No. 680,166, filed July 13th, 1933.

The invention has for its principal-object to provide a novel construction of sewing machine having improved means for varying the stitch formation so as to produce pattern effects upon the material sewn, such, for example, as "dotted swiss effects and various other design eifects. To this end the machine comprises a novel adjustable means for automatically varying the feed of material sewn upon, in combination with means for automatically varying the needle bar operation of the machine to produce groups of straightV run or longitudinal stitches formed under normal or maximum feed conditions, alternated with groups of substantially laterally extending 20 stitches, formed under reduced feed conditions; the arrangement of feed variation control being such that the amplitude of reduced feed is subject to quick and easy adjustment within the range of the amplitude of the normal feed for straight run stitches, thus permitting a considerable range of variation of lateral stitch spacing, with consequent variation or modification of produced pattern or design effects.

Other objects of this invention, not at this timeV 30 more particularly enumerated, will be apparent v in the following detailed description of the invention. Y l

' An illustrative embodiment of the invention is shown in the accompanying drawings, in which:

Fig. 1 discloses a vertical longitudinal sectional view of the machine equipped with improvements vaccording to this invention, certain parts being shown inside elevation; Fig. 2 is a horizontal sectional view, taken partially in the plane of the drive shaft and partially in the plane of the feeder means of the machine; Fig. 3 is a fragmentary vertical longitudinal section, taken on line 3--3 in Fig. 2; Fig. 4 is a fragmentary transverse vertical section, taken 'on line 4-4 in Fig. 1, and drawn on an enlarged scale, the associated eccentric actuated connecting rod being omitted, this viewl showing the feed control means operative for re- V.duced feed operation; Fig. 5 is a view similar to 50 that of Fig. 4, but showing the feed control means operative for normal or maximum feed operation; Figs. 6, 7 and 8 respectively show various illustrativevexamples of pattern effects attained by the improved sewing machine of this invention. Similar characters of reference are employedhangs base I0.

in the above described views, to indicate corresponding parts.

Referring to the drawings, reference character I0 indicates thevbase of a sewing machine having an upstanding pedestal I I from which projects 5 the arm I2, which is spaced above and which over- At the free end of arm I2 is the vertically disposed head I3.

Journaled in arm I2, so as to extend longitudin ally therein, isa drive shaft I4. Pivotally conl0 nected at I5 with the upper end of head I3 is a dependent oscillatable needle-bar guide frame I6, which slidably supports a vertically reciprocable needle-bar I'I equipped at its` lower end with the usual sewing needle I8. Needle-bar I'I l5 is reciprocated by the usual crank transmission I9 which is actuated by drive shaft t4. Fixed on drive shaft I4 is a sprocket wheel 20 which drives, through belt 2|, a sprocket wheel 22- of shaft 23 journaled to extend beneath base IIJ and which actuates the rotary shuttle (not shown) of the machine sewing mechanism.

Supported by head I3 is the usual vertically yieldable presser foot 24 which cooperates with the feed-dog means 25 by whichy the material sewn 25 is controlled and advanced relative to the sewing mechanism. The operative movement of feeddog means 25 comprises a compound of rising and fallingor vertically reciprocal movement and forward and back or horizontally reciprocal movement. The vertically reciprocal movement, which brings the feed-dog means into and out ofv operative contact with material sewn,is effected through oscillation of a rock-shaft 26, the oscillations of which are produced by an eccentric 21 operatively connected thereto by connecting rod 28. Said eccentric 21 is nonadjustable as to stroke or throw. The horizontally reciprocal movement, which causes the feed-dog to advance the material sewnin the formation of each stitch, isI effected through oscillation of a rock-shaft 29, the oscillations of which are produced by an eccentric 30, operatively connected thereto by connecting rod 3l. Said eccentric 30 is adjustable to vary its effective stroke or throw underk certain conditions. f

The means whereby eccentric 30 is rendered adjustable to vary its effective stroke or throw, and thus alter` the amplitude of material feed move' ment of feed-dogmeans 25"comprises a frame l32 50 of which eccentric 30y is a part. This frame A32 is provided at its underside with an arm v33 pivotally secured, byv pivot means 3 4, to the face of sprocket wheel 20, so' that the framel and eccentric 30 may be moved relative to axis of drive 55 shaft I4 by which the frame and eccentric is rotated through its connection with sprocket wheel 20. At its upper side, frame 32 is provided with a lug 35 having a slot 36 concentric to the axis of pivot means 34. Fixed on the adjacent face of said sprocket 20 is a stud 36 which projects into said slot 36. Into one side of said lug 35 is threaded an adjustable stop-screw 31 which enters an end of said slot 36. Threaded downwardly through the end of saidlug 35 is aset-screw 38, which can be tightened down into binding relation to said stop-screw 31, to thereby secure the latter against displacement from any selected operative position to which it has been adjusted.

The frame 32 and eccentric 38 carried thereby are provided with an opening 39 of greater diameter than that of the drive-shaft I4, and through which the latter extends. At one side of frame 32 is provided a laterally extending arm 40 having a tubular bore 4| extending longitudinally,

therethrough. Arranged in the bore 4| is a cornpression spring 42, the outer end of which is backed by a seating screw 43 which is threaded into the outerend of bore. 4|. The. innerrend of spring 42 yieldably thrusts against the side of driveshaft. I4. At the oposite side of frame 32 is an oppositelyand laterallyextending arm `44 having an internally screw-threaded bore 45. Threaded intobore 45 is 4,the threaded base 46 of a thrust pin 41, the latter .extending through the frame opening 39 and through the side of driveshaft |4, 4with .its free end disposed within a hollow tubularinterior orI bore 48 with which said drive-,shaft |4- is provided. Slidable in the interior or bore 480i said drive-shaft |4 is a plunger 49 having at its inner end aconical cam-portion 50. The outer end of said plunger 49 lprojects exteriorly from the'end ofsaid drive-shaft I4. Whenvsaid `plunger is slid or pushed inwardly, its conical cam-portion 50 is moved against the thrust pin 41, thereby pushing the same outwardly, and thus swinging frame 32 and its eccentric 36 about the pivotal connection 34, against the compression of spring 42, to carry the eccentric 30 to maximum offset relation to the axis of driveshaft I4, i. e. to its normal maximum eccentric stroke or throw, under which conditions the straight run or longitudinal stitches are produced. When said plunger 49l is retracted to free thrustpin 41 from the engagement thereof, spring 42 exerts its thrust upon frame 32 to swing the same in the opposite direction until stopped by the engagement of stop-screw 31 with the xred stud 36', thereby disposing the eccentric 30 in minimum offset relation to axis of drive-shaft I4, i. e. for predetermined minimum eccentric `stroke or .,throw, under which conditions the substantially lateral `stitches are produced.

The means for producing lateral oscillations of the verticallyY reciprocated needle-bar I1 and its needle I8 to produce the substantially lateral stitches under reduced or minimum material feed conditions,y whereby the desired stitched pattern or design effects are produced on the material sewn, comprises a rotary cam wheel 5I, shaft or spindle 52 of which-is transversely journaled in the arm I2. ySaid shaft or spindle 52 is actuated by a Worm-gear 53 fixed on its inner end portion and adapted to be driven by a worm 54 fixed on drive-shaft I4. Cam wheel 5| is provided in its fa/ce with a suitably shaped cam groove or Vrace 55. Pivotally mounted on a bracket 56 associated with arm |2-is a lever member, theupwardly extending arm 51 o iwhich is providedv with a roller stud 58 operatively engaged in said ycam groove or race 55. To the downwardly extending arm 59 of said lever member is adjustably connected one end of a connecting rod 60, the opposite or outer end of which is pivotally connected with the needle-bar guide frame I6. The cam' groove or race is shaped throughout a portion of its length to provide a race-portion concentric to the axis of said cam wheel, whereby, when such portion engages roller stud 58, the lever member 51-59 is held stationary, to in turn hold the needle-bar guide frame I6 stationary in perpendicular positionwhen straight run or longitudinal stitches are being formed; the remaining portion of said cam groove or race 55 is of waving formation, whereby, when such portion engages roller stud 58, .lever member 51--59y is oscillated to in turn swing laterally back and forth the needlebar guide frame I6 to produce the substantially lateral stitches. Cam wheel 5| is further provided in its face with a second cam groove or'race 6|. Pivotally mounted on the pedestal is a rocking arm 62 provided with av roller stud 63 to engage in said cam groove or race 6|. Said rocking arm 62 is connected by link 64 with aV second rocking arm 65 which is fulcrumed by a rock-shaft 66 journaled in a bracket 61 attached to said pedestal Fixed on said rook-shaft 66 is a push-lever 68, the free oscillatable end of which is opposed to the outer end of said plunger Said plunger carries at its outer'end a diametrically enlarged end-piece 69, which is outwardly thrust by means of a compression spring i 10 to dispose said plunger 49 in retracted position.

Cam groove or race 6I is shaped to provide an outer concentric portion and an inner concentric portion, the latter being operatively engaged by roller stud 63 to swing inwardly the plunger control means so as to hold plunger 49 inwardly thrust to in turn hold eccentric 30 in maximum throw position so as to actuate the feed means at major amplitude during the production of straight run or longitudinal stitches;' and the outer concentric portion of cam race 6I oper.- atively engagesroller stud 63 to swing outwardly the plunger control means so as to permit plunger 49 to be retracted, to in turn hold eccentric 30 in'minimum or reduced throw position whereby the feed means is actuated at minor amplitude during the production of the substantially lateral stitches.

From the above description it will be obvious that, by the operation of the machine, a. pattern or design stitching may be'sewn` onto material,-

which stitching comprises alternated straight run stitches and groups of laterally disposed stitches, the stitches of the latter groups being -comparatively closely spaced together by means of the reduced operative amplitude of the material feed means which automatically occurs when such-stitching is sewn. In this manner patterns or designs with various dotted effects may be obtained. The lateral stitches may be closely spaced by setting the stopiscrew 31, so as to reduce the throw of eccentric 30 to an amplitude which Will feed the material sewn but for a distance approximating the width of the thread employed, inwhich case the lateral stitches will form a more or less solid dot-like formation of embroidered appearance, such, for example, as shown in Figs. 6 and 8. On the other hand, the stop-screw 31 may be adjusted to stop the frame 32 and dispose the eccentric 30 in any selected position Within the range of its maximum-minimum throw, in which case the lateral stitches may be disposed to form more or less open zig-zag patterns, such, for example, as shown in Fig. '7; The peripheral shape of the lateral stitch produced dots or design patterns, is effected by the specific character of the waved portion of cam-- race 55. For example, said cam race portion may be shaped to progressively increase and then de crease the lateral oscillatory movement of the needle bar 'I1 and needle I8, thus producing dots or design patterns of diamond-like outline, as shownin Fig. 6; or said cam race p ortlon may be shaped to produce uniform oscillatory movement adapted tovproduce dots or 'design patterns .of more orless rectangular outline, as shown in -1 Fig. 8.. It will be obvious thatother outline shapes may also be produced by suitably varying .the shape 'of the waved portion of cam race 55.

Having thus described-myinvention, I claim: 1. In a sewing machine having a vertically reciprocable and transversely oscillatable needle and l cooperating feed means, mechanism for actuating said feed means for both maximum and mini.l imumamplitude of yieeding movement comprisling, a drive shaft, a frame having a feed operatcentric for minimum throw adapted to effect minimum amplitude of Vfeed means movement, means to move said frame in'an opposite direction and hold the same against the tension of said spring to position vthe eccentric for maximum throw adapted to effect maximum amplitude of feed means movement, and adjustable means for varying the stud stopped position of said frame and eccentric to selectively predetermine the scope of minimum amplitude of feed means movement, said latter means comprising an adjustable stop screw carried by said frame to enter an end of its slot in opposition to said stud. l

2. In a sewing machine having mechanism defined in claim 1, wherein the means to move throw position comprises a plunger slidable in said drive shaft, a thrust pin carried by said frame andengageable by said plunger, oscillatable lever .mechanism for actuating said plunger. a rotary

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