US3198153A - Stitch control for plural-feed sewing machines - Google Patents

Description

STITCH CONTROL FOR PLURAL-FEED SEWING MACHINES Filed July 31, 1963 K. WEBER Aug. 3, 1965 2 Sheets-Sheet 1 Fig. 1

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Afl' 2M5) United States Patent 3,198,153 STITCH CONTROL FOR PLURAL-FEED SEWING MACHINES Karl Weber, Kaiserslautern, Pfalz, Germany, assignor to G. M. Pfatf A.G., Kaiserslautern, Pfalz, Germany Filed July 31, 1963, Ser. No. 299,002 Ciaims priority, application Germany, Aug. 1, 1962, P 29,938 Claims. (Cl. 112-209) The present invention relates to sewing machines, more particularly to machines of the type having combined feed dog and roller or wheel feed means, wherein said dog cooperates in a known manner with a work presser 'foot, to intermittently advance the work being operated on, and a pair of auxiliary feed rollers or wheels being operated in synchronism with said dog serve to assist the feeding operation by withdrawing the work after passing the stitching tools of the machine.

In the known plural-feed sewing machines of the fore going type, it is customary to intermittently operate either the lower or upper feed roller, or both said rollers, in synchronism with the feed dog oscillating movements along the usual quadrilateral path, in a manner common with conventional sewing machine design and practice. The feed direction of the driven feed roller or rollers corresponds with the forward stitching direction of the machine, whereby to make it normally impossible to sew reverse stitches by control of said dog by means of an ordinary stitch controller.

As an example, if it is desired to produce reverse barring stitches at the beginning or the end of a seam being sewn, or generally to sew a reverse seam, this is not possible with a conventional plural-feed machine of the type referred to as long as both feed rollers remain in engagement with the work, inasmuch as the teed movements of the feed dog and feed rollers would be opposed during reverse stitching, resulting in tearing or destruction of the work or fabric.

Accordingly, an important object of the present invention is the provision of improved stitch control mechanism -for a plural-feed sewing machine of the general type referred to by which the prior and related difiiculties and shortcomings are substantially eliminated; which may be instantly and expeditiously utilized for temporary reverse stitching by the actuation of a simple operating member (foot pedal, knee lever, etc); by which a change from normal forward to reverse stitching may be effected at any stitch control position or adjustment without change of the stitching length; and which mechanism is both simple in construction and efficient in operation and may be readily structurally incorporated in existing plural-feed sewing machines of the general type referred to and described herein.

The invention, both as to the foregoing and ancillary objects as Well as novel aspects thereof, will be better understood from the following detailed description of a preferred practical embodiment, considered in conjunction with the accompanying drawings forming part of this specification and in which:

FIG. 1 is a front elevation of a plural-feed sewing machine shown with parts broken away and embodying stitch control mechanism constructed in accordance with the improvements of the invention;

FIG. 2 is an expanded perspective view more clearly showing the construction and operative relation of the essential parts of the control mechanism according to the invention; and

FIG. 3 is a partial perspective view showing the drive for the lower feed roller.

Like reference numerals denote like parts in the different views of the drawings.

With the foregoing objects in view, the invention involves the provision, in a plural-feed sewing machine of the general type referred to and comprising stitch-forming means, a work feed dog, and a pair of work-engaging auxiliary feed rollers at least one of which is driven in synchronism with said dog, to intermittently advance and withdraw a work piece being operated on in synchronism with the stitching tools (needle, loop taker, etc.), of an improved stitch controller having adjusting means to alternately operate the same from forward to reverse stitching, and vice versa, said adjusting means being normally urged to a position for forward stitching and the feed dog being provided with suitable feed stroke and direction control means operably connected with said adjusting means, to control the feed direction and stitching length, respectively. There is fiurther provided in accordance with the invention adjustable supporting means and a spring-urged opera-ting member therefore to temporarily withdraw one, preferably the upper, of said feed rollers from the work, said member being operably connected with said adjusting means through suitable lost-motion connecting means, in such a manner as to first retract or withdraw said last-mentioned feed roller from the work and to subsequently effect the change from forward to reverse stitching upon and during the actuation of said member from its inoperative to its operative position for the temporary sewing of reverse stitches by the machine.

As a consequence, provided a suitable time interval for the safe retraction of one of the feed rollers by virtue of the lost-motion coupling, reverse stitching may be effected by the tools (needle, loop taker) of the machine in cooperation with the feed dog in the ordinary manner, as long as the operating member is maintained in the operative position, such as by the depression of springdoade-d foot pedal or actuation of the like control device.

In order to enable a stitch direction reversal at any of the forward stitch adjusting positions of the controller, or for any pre-set stitching length, the stitch control member is advantageously provided with a pair of concentric control cams cooperating with a single cam follower alternately engaging the same by the actuation of said adjusting means. 'By the provision of both said cams with equal and inverse cam surfaces, in respect to a given direction of rotation of said member, an equal stitching length will result from a change from forward to reverse stitching, and vice versa, in any of the adjusting positions of said member and throughout its entire operating range, as will become further apparent from the description.

While the invention will be described in the following in reference to a conventional plural-feed sewing machine of the special type having a feed dog and an auxiliary lower feed roller driven in synchronism, the improved feed controller may be employed in connection with other types of machines of the general character according to the invention, as will become evident as the description proceeds in reference to the drawing.

Referring more particularly to the latter, the numeral 1 denotes the work supporting plate or table of a conventional sewing machine from which extends the casing 2 composed of an upright section and overhanging arm terminating in the sewing head 3. Mounted within the latter is the arm or drive shaft 4 for a vertically recipro cable needle bar 5 carrying, in the example shown, a pair of needles 6 and being operably connected with said shaft through a crank and pin or the like coupling (not shown).

Secured in the rear of the head 3 is a bracket or hearing 7 including a threaded sleeve 9, FIG. 2, vertically movably supporting a lifting rod 8 passing through a bore of said bracket. Secured to the lower end of the rod 8 is a frame 10 embodying a shaft 11 which carries an auxiliary upper feed roller 12 disposed behind a conventional feed dog as viewed in the Work feed direction. In

3 order to apply adequate operating pressure by the; roller to the workbeing operated on, a coil spring 13 encircling the rod 8 is arranged with its one end engaging the lower end of the sleeve 9 and with its opposite end engaging a the same feed stroke or stitching lengthfior both forward and reverse stitching by the machine, respectively.

'movementsbfa separate feed dog 16 supported by a feed {bar 17 and having a serrated upper surface cooperating Linked to the end of the remaining arm 37 of the lever 34 is a connecting rod 38 which has its remaining end linked to the end of a crank 40 being secured to a control shaft 39 journalled in the supporting plate 1; Secured to the end of shaft 39 is .a further crank 42 having a pivot pin- '41. A link 43 serves to connect the crank 42 to a pin 41 acting asan adjustable'fulcrum withthe crank pin 24. In the normal position for zero feed by the dog :16, corresponding to the position shown in the drawing,

'the .axes of the pins 22 and. 41 are aligned or coincide with a work presser foot 1:8, to'intenmittentlyadvance I of the .pin 22 in the horizontal or feed direction of th the Work by a series of quadrilateral periodic feed movements or cycles. For the latter purpose, the feed bar 17 is linked, in the example shown, to a crank '20 which is;

in turn, connected to a sliding shaft'19 carrying a further link 21 having a pivot pin 22. The latter is connected to a crank pin 24 through alink 23, said crank pin being oscillated by the eccentric rod 27 of an eccentric 26 mounted upon a rotating shaft 25 which may be the loop taker drive shaft of the sewing machine being in driving horizontal direction, its verticalmovement being effected, in the example shown, by a further eccentric 29. secured to a rotating shaft 28 and embracing the fork-shaped end i with a single plane, whereby the component of movement dog 16 will be zero, as'will become further apparent as the do cription proceeds.

Journalled within the rear wall of the casing 2 and in the bracket '7 is an operating shaft 44 for the lifting rod 8 carrying the upperfreely rotatable feed roller 12. Secured to the end of shaft 44 adjoining the bracket 7 is a fork-shaped crank 45 having a pair of legs or. crank arms 46 engaging the underside of a pair of diametrical arms or extensions 47 of the lifting member 14. Secured to the remaining end of the shaft44 is a lever 48 to the free end of which is linked a connecting bar 49, the latter being in turn, linked to a sleeve member Stl'having a bore wherein is mounted a bolt 51 and a coil spring 52.

of the barf17, to thereby result in the usual quadrilateral ,1 .feed movements in syn-chronism with the stitching operations. Shaft '28 may be driven by shaft 25 through any suitable motion-transmitting means (not shown) In the example shown, the lower feed roller 15 cooperating with the upper roller :12 may advantageously be 5 feeds-tnoke of the roller 15 may be fixed or adjustable by or feed Stroke of the g 16, respectively;

An extension of lesser diameter of the bolt 51 guided by the sleeve 59 projects into a slot-like recess 53 of said sleeve into which extends further, at right angle to the bolt 51, a follower pin 54 of a'crank or lever 55' secured to the controller shaft33. The front end 56 of the bolt 51 projecting into the recess 53 provides a striking surface for the pin 54, the normal distance between the latter and the surface'56 being greaterthan the operating path of the pin 54 traversed during afull displacement of the control disk '32 from zero to maximum stitching length the aid of suitable adjusting'means similar toth ose for the dog 16 as described in the following. In the former case, the stroke of .the roller: is preferably less than the maximum stroke of the dog 16, to ensure a smooth and driven, or the upper roller may be driven and the lower roller freely rotatable, as will be understood. a 7

FIG. '3shows, by way of example, a 'drivemechanism A tension spring 57 being secured to the plateil, on'the one hand, and to the arm 3060f the lever 34, on the other hand,

, serves to normally cause 'the follower" 35 to engage the 62 connecting the roller 15 with the shaft 28and compris- I ca suf 30f t'th' safe withdrawal of the work for different food strokes of l V m r ace or forward 3 l c mg the dog 16. Alternatively, both said free rollers may be The lower end of the sleeve is linked toa vertical operating rod 59 through an intermediate link 58, rod

59 being guided in a bore in theplate land having secured toits lower end a pull chain 60 orthe like operating member. The entire linkage mechanism as described is urged to its UP or inoperative position, shown in the drawing, by the action of a tension spring 61 having one end secured to the casing 2 and having its opposite end engaging'the lever 48, in such a manner as to allow the bar'49 to be temporarily operated to a DOWN or In order to control the feed stroke of the dog 16 and, in V turn, the stitching length, there is provided a control disk operative position by the actuation of a foot pedaL'knee lever, or the like connected to the rod 59 or chain 60', respectively. I

The operation of the stitch control device described in the foregoing is as follows. The desired forward stroke of the dogjld or corresponding stitching length is first adjusted by rotation of thedisk 32 from the zero positron shown to cause the follower. 35,to engage, a corresponding point of the cam surface 30. In the zero position of the control'ler, thepivot' for the link 43 provided ical-shaped cam follower 35 which projects into the slot enclosed by the surfaces 30 and31'. The curves formed by the pin 41' coincides or is aligned with the pivot for the link 23 provided by the pin 22, whereby the links 23 and 43 driven by the eccentric '26 and eccentric rod 27 perform a pure rotary motion about the pins 22 and 41, respectively, or, in other words, no forward motion will be applied to the feed dogbar17.

:On the other hand, rotation of the control disk 32 and ad ustment of the follower 35 to a desired position of I engagement with thecam surface 30 within the forward in such a manner that, with a given a-djustrnent'of, the 7 control disk 32, the oppositely located points of said curves, upon engagement by the follower 35, provide stitching range, will result, in the connecting rod 38 and crank 40 rotating the'control shaft 39 and crank 40 to a,c0rrespond1ng angular position, whereby to displace the rotating axis or pin41 of the link 42 relative to the position of the rotation axis or pin 22 of the link 23. As a consequence, there is applied to the links 23 and 43, in addition to the rotary motion mentioned, a translatory motion being transmitted by way of the link 21 and crank to the feed bar 17 of the dog 16. At the same time, the lower feed roller 15 is subjected to a similar intermittent feed movement, in such a manner as to intermittently feed and withdraw, respectively, the work by the dog 16 and roller 15 in cooperation with the presser foot 18 and upper feed roller 12, respectively. As will be understood, rotation of the control shaft 39 in the opposite direction from its zero position will result in the feed movement of the dog 16 being reversed for stitching in the reverse direction, such as for the production of barring or the like reverse stitches.

For the latter purpose, the control mechanism is operated by the aid of a suitable operating member (foot pedal, knee lever, etc.), controlled either manually or automatically, to pull the rod 59 in the downward direction against the action of the springs 57 and 61. As a consequence, the supporting rod 8 together with the upper feed roller 12 will be first retracted from the work through the rod $9, connecting link 58, sleeve 50, connecting rod 49, lever 48, shaft 44, crank and lifting member 14, this preliminary operation being made possible by the slot-like recess 5'3 having a length exceeding the total displacement of the lever 54, of the stitch controlled between zero and maximum forward stitching length. There is ensured thereby that the roller 12 will have been fully retracted from the work before the stitching direction is reversed by the striking surface 56 of the spring-urged bolt 51 engaging the follower pin 54 and rotating the lever 34 of the stitch controller by the crank 55 during the continued operation of the foot pedal or the like operating member. As a consequence, the feed direction of the dog 16 will be reversed substantially instantly and the adjustment continued until the follower 35 engages the cam surface 30. Due to the design of the curves 30 and 31 as pointed out, the reverse stitching length is equal to the previously set forward stitching length, the stitching in the reverse direction being continued as long as the rod 59 remains in the depressed position.

The spring 52 is stronger than the return spring 57 of the stitch controller, whereby in case of a too violent operation the bolt 51 is allowed to give way against the action of the spring 52 to prevent damage to or breakage of the lever 34 or other parts of the mechanism. In other words, the spring 52 acts as safety device in cushioning the effects of shocks or excess stress on the linkage mechanism.

Upon release of the foot pedal or the like operating member, the mechanism is automatically returned to the rest or inoperative position shown in the drawing by the action of the springs 52, 57 and 61, in a manner readily understood from the foregoing.

in the foregoing the invention has been described in reference to a specific illustrative device. It will be evident, however, that variations and modifications, as well as the substitution of equivalent parts or elements, may be made without departing from the broader spirit and scope of the invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense.

I claim:

1. The combination with a sewing machine of the type comprising stitch-forming means, a work presser foot, a feed dog, a pair of work-engaging upper and lower feed rollers, means to operate said dog and at least one of said rollers in synchronism with said stitch-forming means, to intermittently advance a workpiece being operated on in cooperation with said presser foot and the remaining one of said rollers, respectively; of stitch controlling means comprising a rotary control member having a pair of adjoining cam surfaces for forward and reverse stitching, respectively, cam follower means and adjusting means therefor to operate the same into engagement with either of said surfaces, to change from forward to reverse stitching, and vice versa, resilient means to normally urge said follower means into engagement with the surface for forward stitching, feed stroke control means for said dog, means operably connecting said control means with said adjusting means, to vary the feed stroke of said dog in respect to zero feed by rotation of said member, said cam surfaces having a configuration to maintain the same feed stroke by said follower means engaging either surface in any adjusting position of said member, spring-loaded operating means to temporarily withdraw one of said rollers from work-engaging position, and lost-motion connecting means between said operating means and said adjusting means, whereby to first withdraw said last-mentioned roller and to subsequently change from forward to reverse stitching upon and during actuation of said operating means.

2. In stitch control mechanism for sewing machines as claimed in claim 1, said feed stroke control means comprising a rotary control shaft having a zero position for zero feed of said dog and adapted to vary the feed stroke in either direction in proportion to its rotation from said zero position in the respective direction, and motiontransmitting linkage means operably connecting said shaft with said cam follower means.

3. In stitch control mechanism for sewing machines as claimed in claim 2, said linkage means comprising a double-lever having a stationary pivot and carrying said follower means at the end of one of its arms, a crank upon said shaft, and a connecting rod having its ends linked, respectively, to said crank and to the other arm of said lever.

4. In stitch control mechanism for sewing machines as claimed in claim 2, said linkage means comprising a spring-urged double-lever having a rotatable pivot shaft and carrying said follower means at the end of one of its arms, a connecting rod linked between the remaining arm of said lever and said control shaft, and means to adjust said pivot shaft between an angular position of engagement of said follower means with the cam surface for forward stitching and a position of engagement of said follower means with the surface for reverse stitching by said operating means.

5. In stitch control mechanism for sewing machines as claimed in claim 1, said operating means being comprised of a spring-loaded lifting rod carrying the upper feed roller at its lower end, and said lost-motion connecting means being comprised of a slidable operating member to lift said rod and having a slot-like recess, and a follower pin movable within said recess and operably connected with said adjusting means.

6. In stitch control mechanism for sewing machines as claimed in claim 5, said recess having an effective length to enable a forward feed stroke control between zero and maximum stitch length prior to operative engagement of said lost-motion connecting means by said pin.

7. The combination with a sewing machine of the type comprising stitch-forming means, a work presser foot, a feed dog, a pair of lower and upper feed rollers disposed behind said dog in respect to the work feeding direction, and means to operate said dog and lower feed roller in synchronism with said stitch-forming means, to intermittently advance a work piece being operated on in cooperation with said presser foot and upper feed roller, respectively; of stitch controlling means comprising a rotating control disk having an arcuate slot shaped to form a pair of opposed and diverging cam surfaces for forward and reverse stitching, respectively, cam follower means within said slot and adjusting means therefor to operate the same into engagement with either of said surfaces, to change from forward to reverse stitching, and vice versa, resilient means to normally urge said follower means into engagement with the cam surface for forward stitching, feed stroke control means for said dog, means operably connecting said control means with said adjusting means, to vary the feed stroke in respect to Zero feed by the rotation of said disk, said cam surfaces having a configuration to maintain the same feed stroke by said follower means engaging either surface inv any adjusting position of said'control disk spring-loaded. operating means to temporarily retract said upper feed roller from the Work, and lost-motion connecting means be- ,tween said operating means and said adjusting means, whereby to first retract said upper feed roller and to subsequently'change from forward to reverse stitching upon and during actuation of said operating'means. 8. In stitch control mechanism for sewing machines as claimed in claim 7, said operating means being comprised of a spring-surged lifting rod carrying said upper feed roller at its lower end, and said lost-motion connecting means being comprised of a slidable operating member to lift said rod and having a slot-like recess, and a follower pin movable within said recess and operably connected to said adjusting means. 1 9. In stitch control mechanism for sewing machines as claimed in claim 8, said recess having an effective length to enable a forward feed stroke control between zero and maximum prior to the operative engagement of said lost-motion connecting means by said pin.

a 10, The combination with a sewing machine comprising stitch-forming means, a work presser foot, a feed dog, and a pair of work-engaging feed rollers disposed behind said dog in'respect to the work feeding direction, and means to operate said dog and at leastrone of said rollers in synchronism with said stitch-forming means to intermittently advance a workpiece being operated on in cooperation with said presser foot and the remaining one of said rollers respectively; of a stitch controller having adjusting means to operate the same from forward to reverse stitching, and vice" versa, resilient meansto norchange from forward to reverse stitching upon and dur- 1 :ing actuation of said operating means.

No references cited.

JORDAN FRANKLIN, Primary Examiner.

Claims (1)

1. THE COMBINATION WITH A SEWING MACHINE OF THE TTYPE COMPRISING STITCH-FORMING MEANS, A WORK PRESSER FOOT, A FEED DOG, A PAIR OF WORK-ENGAGING UPPER AND LOWER FEED ROLLERS, MEANS TO OPERATE SAID DOG AND AT LEAST ONE OF SAID ROLLERS IN SYNCHRONISM WITH SAID STITCH-FORMING MEANS, TO INTERMITTENTLY ADVANCE A WORKPIECE BEING OPERATED ON IN COOPERATION WITH SAID PRESSER FOOT AND THE REMAINING ONE OF SAID ROLLERS, RESPECTIVELY; OF STITCH CONTROLLING MEANS COMPRISING A ROTARY CONTROL MEMBER HAVING A PAIR OF ADJOINING CAM SURFACES FOR FORWARD AND REVERSE STITCHING, RESPECTIVELY, CAM FOLLOWER MEANS AND ADJUSTING MEANS THEREFOR TO OPERATE THE SAME INTO ENGAGEMENT WITH EITHER OF SAID SURFACES, TO CHANGE FROM FORWARD TO REVERSE STITCHING, AND VICE VERSA, RESILIENT MEANS TO NORMALLY URGE SAID FOLLOWER MEANS INTO ENGAGEMENT WITH THE SURFACE FOR FORWARD STITCHING, FEED STROKE CONTROL MEANS FOR SAID DOG, MEANS OPERABLY CONNECTING SAID CONTROL MEANS WITH SAID ADJUSTING MEANS, TO VARY THE FEED STROKE OF SAID DOG IN RESPECT TO ZERO FEED BY ROTTION OF SAID MEMBER, SAID CAM SURFACES HAVING A CONFIGURATION TO MAINTAIN THE SAME FEED STROKE BY SAID FOLLOWER MEANS ENGAGING EITHER SURFACE IN ANY ADJUSTING POSITION OF SAID MEMBER, SPRING-LOADED OPERATION MEANS TO TEMPORARILY WITHDRAW ONE OF SAID ROLLERS FROM WORK-ENGAGING POSITION, AND LOST-MOTION CONNECTING MEANS BETWEEN SAID OPERATING MEANS AND SAID ADJUSTING MEANS, WHEREBY TO FIRST WITHDRAW SAID LAST-MENTIONED ROLLER AND TO SUBSEQUENTLY CHANGE FROM FORWARD TO REVERSE STITCHING UPON AND DURING ACTUATION OF SAID OPERATING MEANS.

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