US3141427A - Loop taker adjusting mechanism for chainstitch sewing machines - Google Patents

Description

July 21, 1964 H. GROSS 3,141,427

LOOP TAKER ADJUSTING MECHANISM FOR CHAINSTITCH sswme MACHINES Filed June 11, 1963 Fig. 4

A 770/? A/E y United States Patent 3,141,427 L00? TAKER ADJUSTING MECHANISM FER CHAlNlTilTQH SEWING MACHINES Hehnnt Gross, Kaiserslautern, Pfalz, Germany, assignor to G. M. Piafi AG, Kaiserslautern, Plalz, Germany, a corporation of Germany Filed June 11, 1963, Scr. No. 287,146 Claims priority, application Germany June 13, 1962 11 flaims. (Cl. 1l2200) This invention relates to chainstitch sewing machines comprising a reciprocatory needle and a thread-carrying hook or loop taker cooperating therewith to produce double chain-stitches in a work piece being operated on, and more particularly to machines of this type wherein the loop taker, being operated in its normal or operative position over a substantially elliptical path in synchronism with the needle, may be released temporarily and operated to a threading position for the easy and expeditious insertion of the loop taker thread prior to the commencement of a sewing operation.

The known constructions for the operation of the loop taker of chainstitch sewing machines from the operative position to a more readily accessible threading position have the disadvantage that the loop taker must be manually returned from the threading. position or its operative or retracted position prior to the starting of a sewing operation. If retraction is omitted due to inadvertence or negligence on the part of the operator, or as a result of tampering or toying with the machine, the loop taker may collide with the needle or other parts of the machine, or the stitch formation may cease, resulting in either damage or breakage of parts or loss of operating time, as well as other drawbacks and defects.

In order to prevent starting of the machine with the loop taker in the threading position, it has furthermore become known to lock the drive shaft of the machine in the threading position of the loop taker by a stop pawl and ratchet or the like mechanism. Aside from the re quirement of additional parts and mechanism, this solution still has the disadvantage that the loop taker must be manually returned to the operative position before a sewing operation can be started.

Besides, attempts have been made in the past to retract the loop taker to its operative position by spring action. Here again, retraction must be released or initiated manually by a control operation or manipulation.

Accordingly, among the objects of the present invention is the provision of improved control or adjusting mechanism for the loop taker of a double chainstitch sewing machine of the type referred toby which the foregoing and related difficulties and defects are substantially eliminated; which mechanism will ensure a ready and instant return of the loop taker from its threading position to its retracted or operative position; which will enable it to dispense with any manual control or manipulation in returning the loop taker to its operative position after threading by automatically retracting the same upon and during the commencement of a sewing operation; which will preclude any damage to the machine parts or loss of operating time due to inadvertence or negligence on the part of the operator; and which mechanism is both simple in design and eflicient in operation and may be readily structurally incorporated in conventional chainstitch sewing machines.

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

FIG. 1 is a side elevation, shown with portions thereof 3,141,4 2? Patented July 21, 1964 broken away, of a chainstitch sewing machine embodying loop taker adjusting mechanism constructed in accordance with the principles of the invention;

FIG. 2 is an enlarged perspective view more clearly showing the loop taker operating and adjusting mechanism embodied in FIG. 1;

FIG. 3 is a partial detail view of the stationary cam plate of FIGS. 1 and 2 serving to initiate the loop taker retraction upon the starting of a sewing operation; and

FIG. 4 is a further partial detail view of the cam or locking disk also forming part of FIGS. 1 and 2 and serving to efiect final retraction and locking of the loop taker in its operative position.

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

With the foregoing objects in view, the invention involves generally the provision in a chainstitch sewing machine of the type referred to and having a reciprocatory needle, a thread-carrying loop taker, a support or carrier therefor, and drive means to operate the same over a substantially elliptical operating path in synchronism with said needle, to sew double chainstitches in a Work piece operated on, of operating or adjusting mechanism to operate said loop taker between an operative position, for carying out a sewing operation, and a threading position, for the insertion of the loop taker thread prior to the starting of the sewing operation, said mechanism comprising essentially means to rotatively support said loop taker by said carrier, and releasable locking means including first resilient means to normally urge said loop taker to its operative and locked position with said carrier. The loop taker and carrier are connected with one another by second resilient means, such as in the form of a coil spring or the like having its ends fixedly engaging the loop taker and carrier, respectively, said second resilient means being arranged to be stressed or tensioned in the normal or locked position of the loop taker with said carrier. As a consequence, manual release of said locking means at a predetermined position of the loop taker within its operating path, such as by depression of an operating lever or the like, will result in the loop taker being operated from its (normally inaccessible) or operative position a (readily accessible) threading position by the action of said second resilient means.

In order to automatically retract the loop taker to its operative position during the starting of a sewing operation there is further provided, in accordance with the present invention, stationary cam means serving as a stop for the loop taker in the threading position, on the one hand, and being adapted to cam with said loop taker or its support or carrier upon and during its initial displacement after starting of a sewing operation, in such a manner as to rotate the loop taker towards and to retract it to the operative or locked position with its carrier by the action of the first resilient means.

The releasable loop taker locking means is advantageously comprised of a disk having a peripheral groove and being connected to a loop taker supporting shaft journalled in the loop taker carrier, on the one hand, and a double locking lever fulcrumed upon said carrier and having one arm engaging the periphery of said disk by the action of said first resilient means which may be in the form of a coil spring connecting the second arm of said lever with said carrier. One edge of said groove is advantageously shaped in the form of a cam or bevelled surface adapted to cooperate with said first lever arm and being correlated with said first cam means such as to cause said lever at first to approach said groove during the initial displacement of the loop taker after starting of a sewing operation, and to cause said lever to cam with and to he subsequently retracted into said groove by said first re- 3,1 3 silient means upon approaching its locked position with said disk, as will become further apparent from the following detailed description of the drawing.

Referring more particularly to FIG. 1, the numeral 1 denotes the working table or bed plate of a conventional sewing machine upon which is mounted a housing 2 comprised in a known manner of an upright and an overhanging arm being parallel to said plate and terminating in a sewing head 3. Mounted within the head 3 is a reciprooable needle bar 4 carrying a needle 5 at its lower end. A main drive shaft 6 being journalled in the overhanging arm of the housing 2 serves to operate the needle bar 4 through a conventional crank and link connection (not shown) and carries a flywheel 7 at its opposite end, said shaft being driven in a known manner by a motor (not shown) through a suitable starting or control device for the carrying out of a sewing operation.

Iournalled below the bed 1 is a loop taker drive shaft 8 which carries a sprocket wheel or the like 9, said shaft being driven, in the example shown, by means of a chain belt 11 cooperating with the wheel 9, on the one hand, and with a further sprocket or drive wheel mounted upon the arm shaft 6, on the other hand.

Further journalled below the bed 1 at a distance from and panallel to the first loop taker shaft 8 is a second drive shaft 12, said shafts being coupled with one another through a pair of gears 13 and 14, whereby to rotate both shaft 3 and 12 at the same speed.

Secured to the front end of the first loop taker drive shaft 8 is an eccentric 15 being encircled by the upper annular-shaped part 16 of an eccentric rod 17. The lower part 18 of said rod is in turn linked, by means of a pin 19, at its upper fork-shaped end to the part 16, while the lower end of part 18 forms the socket or hearing of a ball joint which further comprises the spherical-shaped end 26 of a lever arm or link 21 secured to a loop taker casing or carrier 22. Extending laterally from the carrier 22 is a further arm 23, which is journalled, by means of a pin or shaft 24, in a fork-shaped hearing or adjustable support 25 of the loop taker casing or carrier 22. For this purpose, the support 25 has a shaft 26 extending therefrom at right angle to the pin 24 and being rotatably mounted in the bed 1 or frame of the sewing machine.

Secured to the shaft 26 is one end of a further link or arm 27 the opposite end of which is in turn linked, by means of a pin 28, to the lower end of a further eccentric rod 29 having its opposite end encircling an eccentric 31) mounted upon the end of the second loop taker drive shaft 12. The two eccentric drives 1524 and 26-30 connecting the loop taker carrier 22 with the shafts 8 and loop taker 32 must be threaded by the needle: and loop taker threads, respectively, in a manner well known in the operation of chainstitch sewing machines.

In the example shown, the loop taker support 31 has a depending shaft 31 journalled in the carrier 22, said support having secured thereto the thread carrying hook or loop taker 32 of usual construction. The support 31 is secured axially by the provision of a separating sleeve 33 intermediate said support and said carrier and surrounding the shaft 31, on one hand, and by a cam or locking disk 34 secured to the lower end of said shaft, on the other hand. Fulcrumed in a fork-shaped lateral extension 35 of the casing or carrier 22, by means of a pin 37, is a double locking and release lever 36 which has an angular extension or arm 38 subject to the action of a relatively strong coil spring 40 or the like engaging said arm, on the one hand, and engaging a projection 39 of the casing 22, on the other hand, in the manner shown in the drawing. The ring 34 has a groove 41 adapted to receive the locking lever 36 in the retracted or operative position of the loop taker. One edge of the groove 41 is formed control mechanism described hereinbefore.

4;. with a bevelled or cam-shaped surface 4 FIG. 4, the purpose of which will become apparent as the description proceeds.

Surrounding the sleeve 33 is a further coil spring 43 having one end fixedly engaging the carrier 22 and having its opposite end fixed, in the example shown, to the loop taker support 31, in such a manner as to stress or tension said spring in the normal or locked position of the lever 36 or loop taker 32, as shown in FIG. 2. As a consequence, unlocking of the disk 34 by depressing the lever arm 38 will result in a relative rotation of the support 31 and loop taker 32 from an operative to a threading position by the action of the spring 43, as shown in full lines in FIG. 3 and will be further explained in the following.

Further secured to the bed 1, by means of a set screw 4'7, is a stop and cam plate 45, FIG. 3, being shaped at its end facing the loop taker 32 or support 31 in the form of a curve or cam 48 consisting of two sections 49 and 53 meeting at a common apex S which is positioned at a predetermined distance from the elliptical loop taker operating path 51, as shown in the drawing. Both curves 49 and 5b of the cam 48 are shaped and arranged relative to the loop taker 32 or its operating path 51 such as to result in an automatic return of the loop taker from its threading position, shown in full lines in FIG. 3, to its operative position, shown in dot-dash lines by cooperation with the disk 34 and locking lever 36 during the starting of a sewing operation, as will become further apparent from the following description of the operation of the loop taker Adjustment of the plate 45 is effected by means of the set screw 47 passing through slot 46.

The preparation of a chainstitch sewing machine prior to the beginning of a sewing operation includes, among other adjustments and controls, the threading of the chainstitch loop taker or hook 32. In its normal or operative position, the loop taker, in most practical cases is either inaccessible or accessible with difficulty only, since the hook or eye-opening of the loop taker is normally underneath and concealed by the bed 1 or stitching plate of the machine (not shown). To enable threading, the housing or carrier 22 together with the loop taker are at first operated by continued rotation of the sewing machine to a position corresponding to the end of the return stroke or beginning of the forward stroke within the elliptical loop taker path 51 or operating cycle, as shown in FIG. 3.

Subsequent actuation of the locking lever 36 by digital pressure upon the arm 38 against the action of the spring 40 will result in a deflection of said lever and disengagement from the groove 41 of the disk 34, thereby allowing the spring 43, being normally under stress or tension, to rotate the loop taker support 31 and with it the loop taker 32 relative to the carrier 22 to its threading position, in the manner pointed out hereinbefore and illustrated, in full lines in FIG. 3, the cam plate 45 during this operation forming a stop or abutment for the loop taker in the threading position.

After the loop taker has been properly threaded, the machine may be started for the commencement of a sewing operation, whereby to operate the carrier 22 through 'the eccentric drives 15-24 and 26-30 in the coordinate directions and to result in the loop taker being displaced along its elliptical operating path 51 from the starting point shown in the drawing.

As a consequence, the loop taker 32 or its support 31 by engaging the section 49 of the cam 38 causes the support 31 and with it the shaft 31' and disk 34 to be rotated relative to the carrier 22 until the cam or bevelled surface 44 of the disk 34 engages or cams with the surface 42 of the locking lever 36 sliding upon the periphery of said disk, to thereby result in the retraction of said lever into the groove 41 and locking of the loop taker in its operative position by the action of the spring 411. Return of the loop taker to and locking in its operative position is fully automatic by the cooperation of surfaces 44 and 49 and, in response to the normal starting of the sewing machine for the commencement of a sewing operation. The prior difiiculties and drawbacks are accordingly substantially eliminated by the adjusting and control mechanism of the present invention.

Section 50 of the cam 48 is provided for the sake of safety in case the loop taker threading is carried out inadvertently and the sewing machine started in the opposite loop taker position, that is, at the end of its forward stroke or the beginning of the return stroke within the operating path 51. Again, section 50 by engaging the intermediate arm of the loop taker 32 serves as a stop limiting the deflection of the loop taker to the threading position. As seen from FIG. 3, the long axis of the ellipse 51 includes an angle with the lengthwise axis of the plate 45. During the return stroke of the loop taker 32, the intermediate arm camming with the section 50 again will effect the retraction to the operative position in conjunction with the cam surface 44, in substantially the same manner as described hereinbefore.

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

Having thus described the invention, I claim:

1. In a chainstitch sewing machine of the type having a reciprocatory needle, a thread-carrying loop taker, a carrier therefor and means to operate the same over an elliptical operating path in synchronism with said needle, to sew double chainstitches in a work piece being operated on; the improvement comprising means to rotatively support said loop taker by said carrier for operation between a sewing and a threading position, releasable locking means including first resilient means to lock said loop taker in the sewing position with said carrier, second resilient means connecting said loop taker with said carrier and adapted in the stressed condition and locked position of said loop taker to rotate the same, said loop taker being positioned at a predetermined point of said operating path prior to a sewing operation and being rotated in a first direction from its sewing to its threading position upon release of said locking means and against the action of said first resilient means, and stationary cam means forming a stop for said loop taker in said threading position and adapted to cam with said loop taker during the initial loop taker displacement by said carrier upon starting of a sewing operation, whereby to initiate the return of the loop taker to the sewing position by rotating the same in the direction opposite to said first direction and against the action of said second resilient means to a position for completion of its return to the locked position by the action of said first resilient means.

2. In loop taker adjusting mechanism as claimed in claim 1, said first means being comprised of a shaft extending from said loop taker and journalled in said carrier, and said locking means being comprised of a disk carried by said shaft and having a peripheral groove, and an operating lever fulcrumed upon said carrier and having an arm urged into peipheral engagement with said disk by the action of said first resilient means and engaging said groove in the locked position of said loop taker.

3. In loop taker adjusting mechanism as claimed in claim 2, said lever having a second arm, and said first resilient means consisting of a coil spring connecting said last arm with said carrier.

4. In loop taker adjusting mechanism as claimed in claim 2, said second resilient means consisting of a coil spring surrounding said shaft and having its opposite ends fixedly engaging said loop taker and carrier, respectively.

5. In loop taker adjusting mechanism as claimed in claim 2, said groove having a curved edge adapted to cam with said arm upon said groove reaching a predetermined position from said arm during the return movement of said loop taker.

6. In a chainstitch sewing machine of the type having a bed plate, a reciprocatory needle carrying a needle thread and mounted above said plate, a loop taker having an eyepointed hook carrying a looper thread and mounted below said plate, a carrier for said loop taker and means to operate the same over an elliptical operating path in synchronism with said needle, to sew double chain stitches in a work piece fed along said plate, said loop taker hook occupying a normally inaccessible operative position throughout said operating path; the improvement comprising means to rotatively support said loop taker by said carrier for operation between a sewing and a threading position, releasable locking means including first resilient means to lock said loop taker in the sewing position with said carrier during the carrying out of a sewing operation, second resilient means connecting said loop taker with said carrier and adapted in the stressed and locked position of said loop taker to rotate the same, said loop taker being positioned at a predetermined point of said operating path prior to the commencement of a sewing operation and being rotated in one direction from said sewing position to said threading position upon release of said locking means and against the action of said first resilient means, and stationary cam means forming a stop for said loop taker in the threading position and adapted to cam with said loop taker during the initial displacement of said loop taker by said carrier upon starting of a sewing operation, whereby to initiate the return of the loop taker to the sewing position by rotating the same relative to said carrier in the direction opposite to said first direction and against the action of said second resilient means to a position for completion of its return to the locked position by the action of said first resilient means.

7. In loop taker adjusting mechanism as claimed in claim 6, said cam means being positioned for cooperation with said loop taker in the starting position of its operating path.

8. In loop taker adjusting mechanism as claimed in claim 6, said first means being comprised of a shaft extending from said loop taker and journalled in said carrier, and said locking means being comprised of a disk secured to the end of said shaft and having a peripheral groove, and a double lever fulcrumed upon said carrier and having an operating arm connected to said carrier through a coil spring constituting said first resilient means, and a second lever arm resiliently bearing upon the periphery of said disk and engaging said groove in the locked position of said loop taker.

9. In loop taker adjusting mechanism as claimed in claim 8, said groove having a curved edge adapted to cam with said second lever arm upon said groove reaching a predetermined distance from said arm during the return movement of said loop taker.

10. In loop taker adjusting mechanism as claimed in claim 7, said second resilient means consisting of a coil spring surrounding said shaft intermediate said loop taker and said carrier and having its opposite ends fixedly engaging said loop taker and carrier, respectively.

11. In a chainstitch sewing machine of the type having a reciprocatory needle, a thread-carrying loop taker, a carrier therefor and means to operate the same over an elliptical operating path in synchronism with said needle, to sew double chain stitches in a work piece being operated on; the improvement consisting in the provision of adjusting mechanism to operate said loop taker between a normally inaccessible operative position and an accessible threading position comprising means to rotatively support said loop taker by said carrier, spring-urged manually releasable locking means to normally maintain said loop taker in its operative locked position with said carrier,

resilient means connecting said loop taker with said carrier and adapted in the stressed condition and operative loop taker position, to rotate said loop taker from its operative position to its threading position upon release of said locking means, and stationary cam means arranged to be engaged by said loop taker in the threading position and adapted to cam therewith upon displacement of said loop taker by said carrier after starting of a sewing operation, whereby to initiate the return of said loop taker to References Cited in the file of this patent UNITED STATES PATENTS Zeier et a1. June 6, 1933 Irmscher July 7, 1959 Hacklander July 26, 1960

Claims (1)

1. IN A CHAINSTITCH SEWING MACHINE OF THE TYPE HAVING A RECIPROCATORY NEEDLE, A THREAD-CARRYING LOOP TAKER, A CARRIER THEREFOR AND MEANS TO OPERATE THE SAME OVER AN ELLIPTICAL OPERATING PATH IN SYNCHRONISM WITH SAID NEEDLE, TO SEW DOUBLE CHAINSTITCHES IN A WORK PIECE BEING OPERATED ON; THE IMPROVEMENT COMPRISING MEANS TO ROTATIVELY SUPPORT SAID LOOP TAKER BY SAID CARRIER FOR OPERATION BETWEEN A SEWING AND A THREADING POSITION, RELEASABLE LOCKING MEANS INCLUDING FIRST RESILIENT MEANS TO LOCK SAID LOOP TAKER IN THE SEWING POSITION WITH SAID CARRIER, SECOND RESILIENT MEANS CONNECTING SAID LOOP TAKER WITH SAID CARRIER AND ADAPTED IN THE STRESSED CONDITION AND LOCKED POSITION OF SAID LOOP TAKER TO ROTATE THE SAME, SAID LOOP TAKER BEING POSITIONED AT A PREDETERMINED POINT OF SAID OPERATING PATH PRIOR TO A SEWING OPERATION AND BEING ROTATED IN A FIRST DIRECTION FROM ITS SEWING TO ITS THREADING POSITION UPON RELEASE OF SAID LOCKING MEANS AND AGAINST THE ACTION OF SAID FIRST RESILIENT MEANS, AND STATIONARY CAM MEANS FORMING A STOP FOR SAID LOOP TAKER IN SAID THREADING POSITION AND ADAPTED TO CAM WITH SAID LOOP TAKER DURING THE INITIAL LOOP TAKER DISPLACEMENT BY SAID CARRIER UPON STARTING OF A SEWING OPERATION, WHEREBY TO INITIATE THE RETURN OF THE LOOP TAKER TO THE SEWING POSITION BY ROTATING THE SAME IN THE DIRECTION OPPOSITE TO SAID FIRST DIRECTION AND AGAINST THE ACTION OF SAID SECOND RESILIENT MEANS TO A POSITION FOR COMPLETION OF ITS RETURN TO THE LOCKED POSITION BY THE ACTION OF SAID FIRST RESILIENT MEANS.

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