US2553514A - Hemstitching attachment for sewing machines - Google Patents

Description

May 15, 1951 J. P. ENos 2.55.3514

HEMSTITCHING ATTACHMENT FOR SEWING MACHINES Filed Aug. 26, 1949 2 Sheets-Sheet 1 r@ Fleas May 15, 1951 l J. P. E'Nos 2,553,514

` HEMSTITCHING ATTACHMENT FYOR SEWING MACHINES E Filed Aug. 26, 1949 2 Sheets-Sheet 2 Patented May 15,*1951 :a i.

HEMSTIT'CHING ATTACHMENT FOR SEWING MACHINES John P. Enos, Union, N. J., assignor to The Singer Manufacturing Company, N. J., a corporation of New Jersey Elizabeth,

Application August 26, 1949, Serial No. 112.11.43

9 Claims.

I l i 'This invention relates to hemstitching attachment for sewing machines of the type disclosed fin United States patent to Hinman et al. No. 2,069,652, February 2, 1937.

This invention has as its primary object to 'improve this type of hemstitching attachment by embodying in the attachment means to prevent the skip-ping of stitches due to the so-called nagging of the material being hemstitched.

The attachment disclosed in the above mentioned patent includes, among other elements, a feed-bar having widely spaced work-engaging portions which grip the work and shift it laterally 'and rearwardly and a presser-foot which bears upon the work only during the time that the feedbar is lifted and being returned to its forward position after a rearward feeding stroke, that is, during only one of three upstrokes of the needle. During the other two upstrokes of the needle the work is held down on the work-support only by the widely spaced work-engaging portions of the feed-bar. Because of this widely spaced engagement of the work that portion of the work between the points of engagement of the feed-bar tends to pulsate with the up and down movements of theneedle. This pulsation of the work is known as flagging and frequently prevents the casting of the needle thread loop for entrance by the point of the loop-taker. Failure of the point of the loop-taker to enter the needle thread loop results in a skipped stitch. This invention has as an object to provide an improved presser device for hemstitching attachments which will bear upon the work adjacent the needle during each upstroke of the needle and thereby` prevent upward movement of the Work with the needle, thus insuring the casing of the needle thread loop and preventing the skipping of: stitches.

Another object of the invention is to provide an improved presser mechanism for hemstitching attachments which will engage and bear upon the work between the work-feeding elements during each upstroke of the needle without interfering with the normal shifting and feeding of the work by the attachment. f Y

These objects have been attained by the provision, in a hemstitching attachment of the type disclosed in the above mentioned Hinman et al. patent, of an improved presser mechanism including a main presser-foot having work-engaging and work-releasing movements in timed relation with the` movements of the work-feeding mechanism and an auxiliary presser-foot having work-engagingand work releasing movements in aov " Fig. 4 is an under side view of `timed relation with the reciprocations of the mawill hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention from which the several features of the linvention and the advantages attained thereby will be readily understood b those skilled in the art. I

In the drawings, Y

Fig. 1 is a transverse vertical section of a portion of a conventional lock-stitch sewing machine having my improved hemstitching attachment applied thereto, showing the attachment in side elevation. v

Fig. 2 is a front view of a portion of the sewing machine shown in Fig. 1, showing the front end of the improved hemstitching attachment.

Fig. 3 isv a horizontal section taken substantially on the line 3-3 of Fig. 1 and showing the attachment in plan view. 7

the attachment with a portion thereof broken away.

Fig. 5 is a detail side elevation of portions of the improved attachment showing the relationship between the needle, the feed-plate, and the main and auxiliary presser-feet. Fig. 6 is a view similar to Fig. 5 but with the parts in diierent positions. l

Fig. 7 is a longitudinal sectional view through the attachment.

Y. Fig. 8 is a detail perspective view of a portion of the main frame of the attachment and the main presser-foot forming a part thereof.

Fig. 9 is a detail perspective view of thel auxiliary presser-foot and its supporting lever.

' Referring more specifically to the drawings, the improved attachment is shown asY applied to a sewing machine having a frame including a work-supporting plate l, a bracket arm (not shown) terminating in a head 2 in which is mounted a reciprocating needle-bar 3 to which is secured, by a needle-clamp 4, an eye-pointed thread-carrying needle 5. Also mounted in -the head 2 is a spring-depressed presser-bar 6 which.

when the machine is used for straightaway sewing, carries the usual presser-foot,` not shown.

When the machine is to be used for hemstitchingv including a feed-bar 8 carrying a feed-dog 9, a feed-drive mechanism designated generally as I and a feed-lift mechanism II. In normal straightaway sewing the teeth of the feed-dog operate through slots formed in a throat-plate (not shown) which ts into a cavi y I2 formed in the upper face of the work-supporting plate I. When the machine fis used for hemstitching the throat plate is removed from themachine and there is secured to the upper face of the work plate an improved feed cover plate, designated generally as I3 which supports the work and holds it out of contact with the feed-dog 9, which therefore may partake of its usual four motions without effecting the work. This improved feed-cover plate forms no part of the present invention but is the subject of my United States paent application Serial No. 112,442, filed August 26, 1949.

Cooperating with the needle in the formation of stitches is a conventional rotary hook shown ,onlyin dotted Vlines in Fig, 1 and designated generally as I4. As is customary with this type of `sitch-forming mechanism this rotary hook carries a mass of under thread and is formed with a beak which enters the thread-loop cast out by the upward movement of the needle and expands .that loop and passes the mass of under thread therethrough, thereby forming a conventional lock stitch. Failure of the beak to enter, the needle thread loop results in a skipped stitch, as is well understood.

The present improved hemstitch attachment which, as hereinbeforev stated is generally similar to-the hemstitch attachment disclosed in the Hinman et al. PatentNo. 2,069,652, comprises a--rnain frame including a horizontal bottom plate I5 and upstanding side walls I6 and I1 which aflfo1fd iournals for aV step-by-step rotatable shaft :,Iilater to be described The side wall I6 is formed with an offset vertically disposed U- shapedv portion I9 .designed to embrace the presser-bar 6 and 150. be :secured thereto by the before mentioned screw `1.- Botatabl'y journaled'onthe shaft I8 exteriorly of the side wall IB is the hub a of. an actuating lever 2-,0 which its free end bifurcated at 2Qb Vtostraddle a stud 4a carried by the needlelamp 4. Thus. the 'lever 2Il-is `oscillated on the shaft I8 by the up.andzdownreciprocations of the .needle-bar 3.. .'The'rlever. 20 carries a spring pressed pawl 2| the free .end'of which engages the teethzof a `ratachet wheel 2z `fixed upon the shaft I8. Through the lever 20 and the pawl 2l and .the ratchet wheel V22'the shaft I8 is given steplay-step rotary movements.

Slidingly mounted at the under side of the frame plate I5. for sidewise work shifting and endwse work feeding movements is a feed-plate l2,3 having, on its under side and rearwardly of the Stitching point, a serrated work-feeding portion 24. The feed-plate 23 also carries, at its forward end, space spring fingers 25 and 26 provided with serrated surfaces 21 and 28 respecliVEIY, Which .engage the work and shift it laterally and rearwardly during the hemstitching operation.

show-n most clearly in Figs. '7 and 8, the bottom plate I5 of the attachment frame is provided vat its forward end with a main presserfoot 2-9 which, at certain times `bears upon the work at one side of the stitching point. This presser-foot is formed with an aperture or notch to permit passage of piercer point p forming a part of a work-piercing mechanism designated generally as P. This piercer mechanism is con- 4 structed and actuated substantially the Same as in above mentioned Hinman et al. No. 2,069,652. Inasmuch as this piercer mechanism forms no part of this invention detailed illustration and description thereof is deemed unnecessary. Suffice it to say that it is actuated by reciprocation of the needle-bar and by a cam 3| in the form of a star wheel, secured upon the shaft I 8, as in the vI-Iinman et al. patent.

The feed-plate 23 is slidingly pivoted, at its rear end, to the plate I5 by a stud 32 and is normally urged forwardly and upwardly by a coil spring 33 having one end connec.ed to a lug 6'! projecting upwardly from the plate 23 and its opposite end connected to a stud s carried by the frame side wall I6. vThe feed-plate is shifted rearwardly, in opposition to the spring 33, to give the work its advancing movement, by a cam wheel 34 secured Lo rotate with the shaft I8, a cooperating two-armed lever 13, pivoted at 'I4 to the frame side wall I1, and an abutment member 69 on the Vfeed-plate as in said Hinman et al. patent. Lateral work-shifting movements `are given to the feed-plate 23 by lateral-lyoffset cam surfaces 'I9 formed on a cam disk 35 rotatable with the shaft I8. The cam surfaces 19 operate between vertically disposed lugs 61, 68 pressed upwardly from the feed-plate 23. y v

The disk 35 is formed on its periphery with four cam surfaces 'I1 and four concentric surfaces or dwells 11ewhich operate successively on the upper surface of the feed-plate 23 as shown most clearly in Fig. 7. The surfaces 11 and 1`IEL are connected by an abrupt shoulder 18. Under the urge of the spring 33 the upper surface of the feed-plate is constantly pressed against the periphery of the disk 35. Adjacent the intermediate portionof the feed-plate 23 and slightly toone side of .a vertical plane containing the axis of the shaft I8 the metal of the plate is displaced downwardly, as :shown at 62, to provide a recess 63 into which drops at certain times, the concentric portion of the `cam disk 35 adjacent the shoulder 18 thereby permitting the feed plate to Ybe raised by the spring 33. As the disk is turned from thispoint, the cam ysurface I1 of the disk 35 forces lthe feed plate downwardly to cause the ' serrated portions 24, 21 and 28 to bear upon andl grip the work supported by the feed cover plate I3. After the work has `been firmly gripped and-further lowering of the feed plate is precluded, further action of theI cam surface. 11 `on the feed plate causes the entire attachment exclusive ofthe feed-plate 23k to be raised. This 'action lifts the main presser-foot 29 above the wor-k and permits thesidewise and endwise move.- ments of theA feed plate to :give to the work the required rnovemei-rts ,to produce hemstitching. The concentric portion 1'Ia of the disk maintains the feed-plate depressed until after the threestitch hemstitch cycle .has :been completed and the work has been fed toward the rear of the machine. At the completion of this feeding stroke theshoulder 18V is aligned with the recess 63 thus permittin-g the attachment frameA and the presser-foot. 29 carried thereby to bev lowered under the influence of the presser-bar' spring and also .permittingthe feed-plate 23 to be raised 'by the spring 33 and to be shifted forwardly thereby as soon as one of ther high points-iBI -of the cam wheel34 has been rotated out of Contact with the lever 13. y

From the foregoing it -wi-ll be understood that the. main presser-foot 2.9 bears upon the work during the forward return of the feed-plate 23 'and Ldu'rihg only "on'e of each three upstrok'es of 'the'itneedle in aVthree-stitch hemstitchv cycle. During the other two.A upstrokes of the needle the feeding portions 24, 21 and 28 of the feed-plate 23 bearupon the work and the presser-foot 29 is maintained above and out of contact with the work. `Heretofore it has been during these two upstrokes of the needle; i. e.'when the work was held downward only by the widely spaced feeding portions 24,` 21 and 28 ofthe feed-plate, that the portion of the work in the region of the needlev tended to ag, which frequently caused the skipping of stitches as hereinbefore explained.

This invention has; provided an auxiliary presser device which is actuated in timed relation with th'ereciprocations of the needle and. which includes afoot adapted to bear upon the work adjacent the needle at each upstroke thereof, thereby positively to preclude flagging'of the work andthe consequent skipping of stitches.

"This auxiliary presser device comprises a horiiotally disposed presser lever 36 fulcrumed, in-

termediate its ends, upon a shoulder screw 31 threaded into an aperture 38 in the frame side wall 16. 'I'he front end of the lever 36 has a lat` erally offset portion 36a to the downturned end of which is pivotally mounted an auxiliary presser-foot 39. The auxiliary presser-foot is located at the side of the needle opposite to the main presser-foot and has a toe portion 33a which extends forwardly beyond the toe"l of the main presser-foot. Theauxiliary presser-foot also has a heel portion 40 `provided with a thread-clearance aperture 4| rearwardly of the path of reciprocation of the needle.

: The rear half ofthe presser lever 36 is'cut away as at 3Bb to avoid interferencewith the ratchet wheel 22 and is` provided with an -end portion 36 adapted to be engaged by acam`42 Yformed on thenhub V2!)a Aof the actuating lever 20. AAspring 43'fsurroundinga screwV 44and having one leg engaging the side wall I6 and another leg engaging beneath the rear half of the lever 36 normally urges the lever counterclockwise as viewed in Fig. 1, thereby tending to depress the auxiliary presser-foot 39 into contact with the work,-desig nated as W in Figs. 5 and 6.

In Fig. 5 the needle-bar3, needle 5 and the lever are shown in full lines in their lowermost positions. In this position the cam 42 on the hub of the lever 20 is spaced angularly from the portion 36c of the lever 36. As the parts move from the position shown in full lines to the position illustrated in dotted lines the cam portion 42 has no effect on the lever 36 and therefore the auxiliary presser-foot 39 remains in pressure contact with the work. It is during this interval that the needle has its initial upward movement which casts out the needle-thread loop for entrance by the beak of the loop-taker. After the needle-loop has been seized by the loop taker the needle-bar and the lever 20 have a further upward movement which causes the cam 42 to engage the rear end of the lever 36 thereby turning that lever clockwise (Fig. 1) and liftingl the auxiliary presser-foot 39 off the work to permit the work to be shifted by the feed plate 23.

From the foregoing it will be understood that the main presser-foot 29 cooperates with the work-feeding elements 24, 21 and 28 on the feedplate 23 to hold the work stationary during'the time that the feed-plate is out of contact with the work. Also, that the movements of the auxiliary presser-foot 39 are so timed with the recip'ro'catins of `-the needle-bar ardneedle as to hold the work against flaggingv during each initial upstroke of the needle and to be lifted off the work during each lateral and rearward movement of the work by the feed-plate 23.

Having 'thus 4set forth the nature of the invention, what I claim herein is: 1. A hemstitching attachment for a sewing machine having a reciprocating needle, including a' feed-plate adapted to engage and feed the Work rearwardly of the machineand laterally of the *line of seam formation in two directions, means operative after each complete feeding cycle for raising said feed-plate out of Acontact with the work, means to shift said feed-plate fori, wardly while it is out of contact with the work; a main presser-foot constructed and arranged to bear on the work during the time that the feed-plate is out of contact with the work, and an auxiliary presser-foot actuated in timed relation with the reciprocations of the needle and designed to bear upon the work during each up- Y stroke'of the needle.

21A hemstitching attachment for a sewingl machine having a reciprocating needle-bar and a needle carried thereby, including a feed-plate having sidewise and endwise movements adapted to engage and feed the work laterally and rearwardly of the machine in a predetermined threestitch cycle, means operative after each third stitch for raising said feed-plate out of contact with the work to permit it to be shifted forwardly preparatory to the beginning of a new feeding cycle, a main presser-foot constructed and arranged to bear upon the work during the time that the feed-plate is out of contact with the work, and a vertically movable auxiliary presserfoot actuated by the reciprocations of the needlebar and designed to bear upon the work during each upstroke of the needle. f

3. A hemstitching attachment for a sewing machine having a reciprocating needle-bar, and a thread-carrying needle carried thereby, including a frame, a feed-plate carried by said frame and adapted to engage and feed the Work, an actuating lever fulcrumed on said frame4 and operated by the reciprocations of said Aneedlebar, means actuated by said lever for periodically raising said feed-plateout of contact with the work, a main presser-foot secured-to said frame, said presser-footbeing constructed and arranged to bear onthe work during the timethat the feed-plate is out of contact with the work, and an auxiliary presser-foot fulcrumed on said frame and designed to bear upon the work during each upstroke of the needle.

4. A hemstitching attachment for a sewing machine having a reciprocating needle, including a feed-plate adapted to engage and'feed the work, means periodically raising said feed-plate out of contact with the work, a vertically movable main presser-foot constructed and arranged to bear on the work during the time that the feed-plate is out of contact with the work, and an auxiliary presser-foot designed to bear upon the work adjacent the needle during the initial portion of each upstroke of the needle.

5. A hemstitching attachment for a sewing machine having a reciprocating needle-bar and a thread-carrying needle carried thereby, comprising a frame, an actuating lever fulcrumed on said frame and operated by the reciprocations of said needle-bar, a presser-lever fulcrumed on said frame, a presser-foot carried by said presserlever and designed to bear upon the work adja- Y eentfsaid; eedle., spring mansanormallyibiasing said pnesser-leyer :to a :position to -pcause said presser-foot to bearnpon fthe .wor-k, .and a vmember carried :by v.said actuating 'lever and `acting on said .presser-,lever to :lift s aid presser-foot lfrom fthe 1workinnpposition to said spring means after the needle-bar has been fl'ifted sufficiently tocauselthe needle .to `'cast its thread loop.

1.5.' ,A :liemstitchingV .attachment for fa :sewing machine having a greciprocating needle-bar Vand a threadeoarrying `.needle carried thereby, comprising .a flame, Jan actuating :lever fulcrumed onsaid framefand operated lby therecprocations of :said needle-har, a horizontally .disposed presserlever iulcrnmed intermediate its ends on said iframe, a presser-foot carried by one :end

of said presser-lever :and designed to bear :upon the amerik adjacent said needle, spring means normally ,biasing said v.presser-lever to a position to ..eausenaidfpresser-footto -bear upon :the Work, and a cam member carried by Said actuating leyerand acting 0n thegother end of'rsaid presserlever during each upstroke of tthe needle-bar'to lift `said presser-footfrcm theyvork in opposition to said `spring means after ithe :needle-bar has been lifted ,s-.uciently ato cause :the needle :to form @a `dah-read :loon- .iA :hemetitohine attachment for -a :sewing machine having ya reciprocating needle-bar vand a tl-1rea-d-,earry1lgsneedle carried thereby, lcollinr' e a Yframe, actuating lever fulcrumed on saidrframeand-openatedby-the reeiprooatons of needle-bar, `a .presser-lever ffulcrumed :o11 said frameea;pteser-footecarriedrby said presserlever and desienedto-bear upon the lwork adiaoent ,said needle, ,spring meansfnormally 'biasing said nresser-jleyer -to aa :position to v cause said presser-foot to :bear ,upon :the work, and a cam carried :by `said actuating lever and acting on said presser-lever to 'lift said presser-'foot from the `Work in opposition to said lspring means, there :being Asufficient V.lost 'motion between v.said cam and Vvsaid lever to .delay the movement of the :lever .and the presser-foot ,carried fthereby until the needle-bar has sheen `lifted sufficiently to lcause `the .needle .to 4vcast a thread loop.

"8. A hemstitching attachment for -a V,sewing machine 'having a :vertically reciprocating thread-carrying needle, including a fvertically and horizontally movable feed-plate adapted to engage land :feed `the \work, a main :presser-doot constructed sand :arranged .to bear :upon the lWork when nahe feed-@late is elevated, and a `,vertically movable 'auxiliary presser-foot Yactuated. in :timed relation with the reciprocations of said needle, said auxiliary presser-.foot being :constructed and arranged to bear upon :the Work adjacent the needle vduring the Iintial portionlof eachupstroke of the ,needle to Jprevent yflagging of the .Work-.durf ing vvthe casting of the needle-thread loop.

9. A hemstitohing attachment :for va sewing machine `having a reciprocating Vneedle-,bar fand a needle carried thereby, including :a feed-plate, means lto .eine to ,said feedplate sidewise and endwise :movements g-toeedza work-piece laterally in f two ldirections and ',thencerrearwardly of the machine in each vcomplete feeding cycle, means operative after the completion of each feeding cycle for raisinesaid feed-,plate out of contact with the work tto permit ,the feed-plate to be shifted forwardly Vpreparato..rif V.to the beginning of anew feeding eyele. :and :a vertically movable presser-doot actuated by the reoiprocatipns of the needle-berend designed to 'bear upon fthe work during e.ach:upstr oke0f thelneedle.

JOHN jP. ENQS.

REFERENCES (DIT-ED The following references are of record in the file of this patent:

UNITED STATES 'PATENTS

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