US3100469A

US3100469A - Throat plate for overedge sewing machine

Info

Publication number: US3100469A
Application number: US136265A
Authority: US
Inventors: John M Washburn
Original assignee: Merrow Machine Co
Current assignee: Merrow Machine Co
Priority date: 1961-09-06
Filing date: 1961-09-06
Publication date: 1963-08-13
Anticipated expiration: 1980-08-13

Description

Aug. 13, 1963 J. M. WASHBURN THROAT PLATE FOR OVEREDGE SEWING MACHINE 2 sheets-sheet 1 Filed Sept. 6. 1961 Z JX J 25% Wv-M Aug. 13, 1963 J. M. WASHBURN THROAT PLATE FOR OVEREDGE SEWING MACHINE Filed Sept. 6, 1961 2 Sheets-Sheet 2 Jflll/nM Basil/burn United States Patent O" .This invention relates to throat plates employed in overedge sewing machines, and more particularly to an improved stitch finger assembly for loveredge machines employing two needles in side by side relationship.

Inthe formation of certain types of seams, two rows of needle thread loops are placed in the Work material along lines parallel to the work material edgeand a third thread is manipulated by the loopermechanism of the machine to be interlooped with both series of needle thread loops. To accomplish this operatiom in certain seams it is necessary that the machine be provided with two stitch fingers, one of which extends between the two rows of needle thread loops. In the formation of the seam, the needle whichforms the row of loops remote from the work material edge carries its thread downwardly through the fabric to a point below the lower edge of the last mentioned stitch finger into operative relationship with the looper which carries the loop laterally beneath the stitch finger. As the material is fed through the machine, the loop slides longitudinally along the stitch finger until itslips oil the distal end of the finger.

In many types of seams; the lateral spacing between the two rows of needle thread loops is quite small, and since the inner stitch finger must project between the two rows of loops" While permitting clearance so that the needles can pass down on opposite sides of the stitch finger, the finger must, of necessity be of relatively small width. At the same time, because of the high speed of feed, 'thestitch finger must have a reasonable length, thus resulting in a requirement that the stitch finger be relativelylong, thin and cantilevered from the throat plate in order that the stitches may slip freely from its distal end. During the formation of the ,stitches, the needle thread loops are drawn taut while they are still on the stitch finger.

This action exerts a pull on the stitch finger :which, because of the design requirements referred toabove, subjects the finger to vibration when in use. Thus,the stitch finger, because of its dimensions, is readily subjected to damage and, if formed integrally with the throat plate, is a primary cause of damage requiring replacement of i the .complete throat plate. Previous efforts to provide thnoat plate construction in which the stitch finger may bereplaced without discarding the entire plate have not proved completely satisfactory because of difficulties encountered in providing-satisfactory means for securing the finger on the plate with sullicient rigidity to resistthe tendency machine'isoperated. I fA'ccordingly, isan object of thepresent invention to provide a throat plate for i use ill a two needle overedge sewingrn-achine having replaceable stitch finger'which ofthe finger to vibrate whenthe rn'ay be rigidly secured to the, throat plate.

5 In the achievement of the foregoing, and other objects, a throat plate assembly is constructed with an upwardly opening groove of uniform width and varying depth formed in the upper surface of the plate. The inner stitch finger is separately formed from sheet material having a thickness which provides a sliding fit between the sidewalls of the groove in the throat plate. At one end, the stitch finger is formed with a finger portion having a maximum thickness at its base substantially equal to the thickness of the throat plate and tapering toward the distal or free end of the finger to permit thread loops 3,100,469 Patented Aug. 13, 1963 2 to slide easily from the finger portion. The. opposite end portion of the stitch finger -is formed as a shank or tang whose vertical dimension is somewhat less than the depth of the groove in the throat plate; The groove in the throat plate is formed with a fiat bottom portion whichextends from the inner end of the needle receiving slot within which the stitch finger islocated lengthwise of the throat plate to terminate at oneend of a depressed intermediate bottom portion of the. throat plate groove. The con-figuration of the stitch finger and bottom portion of the groove is such that when its tang is initially placed in the groove, the lower surface of the tang contacts the groove only at two points, one at the forward end of the flat portion adjacent the inner end of the needle receiving slot and the other point of contact being near the end of the depressed intermediate portion of the groove remote from the flat portion. .At a location longitudinally of the slot substantially midwaybetween the inner end of the flat portion and this latter point of contact, a bore extends through the body. of the throat plate traversely across the slot. A wedging pin having a tapered wedge section is received within this bore and its tapered portion is adapted to engage a notch in the upper surface of the tang so that when the pin is driven laterally across the slot, the tapered portion of the pin forces the tang portion downwardly and rearwardly within the groove to seat the forward end o-f-the tang portion in faceto face contact with the flat portion, thereby resiliently locking the stitch finger in position upon the plate. The lower portion of the base of the finger portion of the stitch finger is formed with an upwardly and forwardly inclined shoulder surface which extends upwardly from the lower side' of the stitch finger and is hooked over the edge surface of the throat plate at the inner end of. the slot.

The, rearward and downward wedging action exerted on the stitch finger tang by the wedge pin tends to move this shoulder toward engagement with the oppbsed surface of the throat plate, thus exerting a firm longitudinal locking action on the st-itchfinger. The downwardyfiexing action flexes the relatively large ,ve'rtical depth. of thestitch finger which serves to increase the rigidity of the finger'when the machine-is in operation. .F

\ of FIG. 1, showing the. assembly without the removable stitch finger or wedgingpiny: BIG. 4 is a cross-sectional view similar to FIG. 3*show ingthe remov ablestitch finger in :place within its .re'-

ceivinggroove prior tofthe placementof the wedging pin,

and." A

l BIG. is a cross-sectional ilietwaisimilar toFIG; 3 showingthe parts in theirrassentbled relationship. Referring first to FIG; 1, there is shown a throat plate lthrformed with a feed dog receiv-' a relieved feed dog receiving recess 14 which accommodate motion. of the feed dogs of designated generally ing opening 12 and the machine ina well known mannerto feed work material indicated in broken line at W. through the machine in the direction; indicated by arrow 16. Throat plate 10 isbored as at 18 to receive a screw whichis employed to mount the plate upon the machine in the general fashion indicated in my prior Patent No. 2,233,088, granted February 25, 1941, to which reference may also be had for the general relationship of throat plate 10 in an overedge sewing machine.

the 1 assembly of dog opening 12 as at 42.

Immediately to therear (the terms ifront and rear refer to the direction of feed, the direction of feed moving the work material from front to rear) a first stitch finger 24 is formed as an integnal part of throat plate 10. The inner edge 22 of stitch finger 26 is lo cated in spaced parallel relationship to aside edge 24 on throat plate edgesf22' and 24 defining the longitudinal sidewalls of aneedle receiving slot whose inner I end is defined by a traversely extending edge 25' on throat plate 10. i The transverse width" of the needle re-' ceiving slot is such that thread carrying needles of ah overedge sewing machine upon which the throat plate is f employed pass'vertically through the slot at locations indicated in FIG. '1 at 28 and 30. i V

A groove designated generally 32 is (formed in the upper surface of throatplate 10 and, as best seen in FIG. 1, extends substantially entirely across the upper.

surface of throat plate 10 from transverse edge 26 in longitudinal [alignment with the longitudinal center line of the needle receiving slot. ,Groove 32 is: of uniform width and has spaced parallel vertical sidewalls.

. The configuration of the lower wall of groove 32 is best seen in FIGS. 3 through 5. At the end of groove 32 "adjacent totransverse edge 26, the lower wall of groove t 32 is ionmed with a flat downwardly land inwardly inclined portion 34. At its inner end, fiat portion 34 terminates at one end of an intermediate portion 36 which, since it defines the maximum depth of the groove 32 relative to the upper surface of throat plate 10, will he referred to as a depressed portion. Throat plate 1%} is formed with a transverse bore 3 8 which, as best seen in FIGS. 1 land 2, extends from the sidewall lll of throat I right to left as viewed in FIG. 2, tapered portion 68 passesthrou gh notch 64 and enters that portion of bore plate 10 transversely across groove 32 to open into feed 7 dog opening 12. Preferably, for reasons discussed below, bore 38 is extended to similarly pass through that portion of throat plate 10 on the opposite side 'offeed .--Groove 32 and bore 38 are formed in throat plate 10 for the purpose of locating and securing a stitch finger element designated generally 44 in position upon the throat plate; Stitchtinger element 44 is constructed from plate or sheet material having athickness adapted to ibe: snuglyreceived between the: lvertical sidewalls sliding'element 4a to the right as viewed in FIG.'4 until shoulder 5% contacts the lower portion 62 of transverse edge 26 of the throat plate. Dower portion 62 of edge 26 is inclined upwardly and forwardly at a slightly greater angle than shoulder 50. A notch 64 is cut into the upper edge of tang portion 48 at a location such that when shoulder 5t contacts edge 62, notch '64 is disposed longitudinally within groove 32 in alignment with bore 38.

A wedge pin 66 is received within bore 38 a loose drive fit. The inner end of pin 66 is tapered as at'68 (FIG. 2) so that as pin 66' is driven into bore 38 from 38 to the left of groove'32 aswiewedin'FIG. 2. Further driving movement of pin 66 to the left'as' viewed in FIG;

4 position until its upper edge'7il is moved into substantial parallelism with the upper surface of stitch finger 20. The maximum depth of notch 64 is located somewhat to the left of the center of bore 38 as viewed in FIGS. 4 and 5 and hence the wedging action of tapered portion 68 of pin 66 is also applied against the inclined right hand portion of notch 64- to urge stitch fingerelement 44 to the left at the same time that tang portion 14.8 is flexed downwardly by the-pin. This action thus also resiliently wedges shoulder 50 toward lower edge portion 62 of transverse edge '26. I a e I The foregoing construction achieves a central or inner stitch finger on =th'roat plate v1t) which is held in position extremely rig-idly by virtue of the wedging action of of groove 32 andis formed atone-end with a stitch finger portion 46, the remainingportion (right hand portion as I viewed in FIGS. 4 and 5) being tormed as an elongate tang 48. I V

. Stitch finger element 44 has its maximum vertical dimension or depth at the base of finger portion 46, at which pointgthe depth of finger element'44 issubstantially equal to the vertical thickness of throat plate 10. Since groove I '32 extends downwardly-onlypartially through throat plate 10, the base-of finger portion 44 is defined in part by an upwardly andto'rwardly inclined shoulder-50 which extends upwardly from. the tapered -loweredge 52 of finger portion 46 to-merge-t-hrough' a smooth curve into the fiat lower edge 54 of tang portion 48. The upward -and orwardt-aper of. loweredge52 of finger ,por-

tior1=46 facilitates the smooth sliding of thread loops along the stitch. finger ip the direction of work material feed I (toitheleftas:viewediirifFIGSs l and 5) until the thread seeps-sup trom'the'..stitch tinger atit'sdistal end 56.

' As best seen in FIG. 4,: the shape of the lower edge 7 point of contact fitl being between the extreme end of tang portion 48 and a location adjacent the end of depressed portion 36 remote from flat portion 34. Between the two points of contact 58 and 60, thelower'edge 54 offstitchiinger element =44 is such that when the element I is placed in groove 32, tang portion 48 contacts the lower.

.; wall of groove 32 only'a-t two points, one point ;58 being located 'near the outer end of flat portion 34 and the other pin '66; Iihe application of the wcdging force to urge shoulder tightly against edge 62 firmlylocks the stitch finger element against longitudinal movementwithin the slot and the provision of the shoulder at 'the'sa'me-t-ime ermits the vertical thickness or depth of the finger por-,, tion 46 to he made relatively large to ,further increase the rigidity of the operative portion of the stitch linger. Stitch finger. element 44rmay be readily removed by insetting a drive pin through bore 42" to drive pin 66 out of V bore 38f I While one embodiment of the invention has been described in detail, it will be apparentto those skilled in the art that the disclosed embodiment may he modifiedi Therefore, the foregoing description is to beconsideredj exemplaryrather than limiting and the true scope of the" I invention is that defined in theiollowing claims. What is claimed is: a

1 For use in an bveredge sewingmachine; a-ithroat plate having a first fingerthereondefiningan elon-. gate'vneedle receiving slot having spaced 'longitudinalvsideedges and a transverse edgedefining. the inner endof saidslot, said plate having'an upwardly opening groove therev in extending tromfsaidtransver'se edge across the upper,

side or said plate, an elon gate plate-lik'e secondstitch: i

linger member having agstitch linger portion atone end 7 1 V and an elongate tang, said tang being adapted to be re.

ceived within said groove with the opposed sides of said tangengaged with the side surf-acesv of said groove tolecate said-finger portion in a central longitudinally extend -I ing position within said slot, the lower suhfiace of said of tan-g 48 is vertically spaced above lower wall 3436 of groove 32.

Stitch finger element 44 is assembled to throat plate 7 10 by first placing tang portion '48 in groove 32 and groove having an intermediate portion thereof depressed relative to the opposed lower surface of said tang, a shoulder on said member engageablelwith said transverse;

edge, and wedge means engageable between said plate and the upper surface of said tang at a location above said dep essed portion of said groove for flexing said tang port1on downwardly within said groove to resiliently lock said second stitch finger member to said plate.

a stitch finger portion at one end of said second stitch finger member, a tang integral with said stitch finger portion and adapted to be received on edge within said groove to locate said stitch finger port-ion centrally within said slot, a downwardly projecting shoulder on the lower side of said second stitch finger lmember engageable with. said transverse edge of said slot to longitudinally locate said stitch finger portion within said slot, the lower surface of said groove having an intermediate portion therei of depressed relative to the opposed lower edge surface of said tang, and wedge means engageable between said plate and the upper edge surface of said tang portion a above said depressed intermediate portion of said groove for flexing said tang portion downwardly within said groove and urging said shoulder against said transverse edge to lock said second stitch finger member to said throat plate.

3. A throat plate as defined in claim 2 wherein said wedge means comprises a wedge pin, said throat plate having a bore therethrough extending transversely across said groove and receiving said wedge pin, the upper surface of said tang having a notch therein adapted to engage said wedge pin to depress said tang portion and to urge said shoulder against said transverse edge upon sliding movement of said pin transversely across said groove.

4. A throat plate as defined in claim 2 wherein the lower surface of said groove includes a flat portion extending between said depressed portion and said transverseedge, the lower surface of said tang being fiat and 6 adapted to engage said flat portion at a point adjacent said transverse edge and to engage the lower surface of said groove at the side of said depressed portion remote from said fiat portion when said wedge means is disengaged there-from, said wedge means being operable to flex said tang portion downwardly Within said groove until the lower edge of said tang is in face to face contact with said fiat portion of said groove throughout the length of said fiat portion.

5. For use in .an overedge sewing machine; a throat plate having a first stitch finger thereon defining an elongate needle receiving slot open at one end and having spaced longitudinal side edges and a transverse edge defining the inner end of said slot, said plate having a groove therein extendingyfrom said transverse edge lengthwise on one side of said plate, an elongate plate-like second stitch finger member having a stitch finger portion at one end and an elongate tang, said tang being adapted to be received within said groove 'with the opposed sides of said tang engaged with the side surfaces of said groove to locate said finger portion in a central longitudinally extending position within said slot, the bottom surface of said groove having an intermediate portion thereof depressed relative to the opposed surface of said tang, a shoulder on said stitch finger member engageable with said transverse edge, and means slideably received Within said plate and engageable with said tang at a location opposed to said bottom portion of said groove for flexing said tang portion in a direction Within said groove to resiliently lock said second stitch finger member to said plate.

References (Iited in the file of this patent Maier Mar. 10, 1931

Claims

1. FOR USE IN AN OVEREDGE SEWING MACHINE; A THROAT PLATE HAVING A FIRST STITCH FINGER THEREON DEFINING AN ELONGATE NEEDLE RECEIVING SLOT HAVING SPACED LONGITUDINAL SIDE EDGES AND A TRANSVERSE EDGE DEFINING THE INNER END OF SAID SLOT, SAID PLATE HAVING AN UPWARDLY OPENING GROOVE THEREIN EXTENDING FROM SAID TRANSVERSE EDGE ACROSS THE UPPER SIDE OF SAID PLATE, AN ELONGATE PLATE-LIKE SECOND STITCH FINGER MEMBER HAVING A STITCH FINGER PORTION AT ONE END AND AN ELONGATE TANG, SAID TANG BEING ADAPTED TO BE RECEIVED WITHIN SAID GROOVE WITH THE OPPOSED SIDES OF SAID TANG ENGAGED WITH THE SIDE SURFACES OF SAID GROOVE TO LOCATE SAID FINGER PORTION IN A CENTRAL LONGITUDINALLY EXTENDING POSITION WITHIN SAID SLOT, THE LOWER SURFACE OF SAID GROOVE HAVING AN INTERMEDIATE PORTION THEREOF DEPRESSED RELATIVE TO THE OPPOSED LOWER SURFACE OF SAID TANG, A SHOULDER ON SAID MEMBER ENGAGEABLE WITH SAID TRANSVERSE EDGE, AND WEDGE MEANS ENGAGEABLE BETWEEN SAID PLATE AND THE UPPER SURFACE OF SAID TANG AT A LOCATION ABOVE SAID DEPRESSED PORTION OF SAID GROOVE FOR FLEXING SAID TANG PORTION DOWNWARDLY WITHIN SAID GROOVE TO RESILIENTLY LOCK SAID SECOND STITCH FINGER MEMBER TO SAID PLATE.