US2730980A - Thread pulling device - Google Patents

Description

1956 c. J. M. BENINK 2,730,980

THREAD PULLING DEVICE Filed Aug. 20, 1954 Fig.7

a- Fig.3

2o /6 o 21 Q 3 i 15 Ill 41 T 29 b UnitedStates Patent THREAD PULLING DEVICE Christian Josef Marines Benink, Kaiserslautern, Germany, assignor to G. M. Pfaif A.-G., Kaiserslautern, Pfalz, Germany, a corporation of Germany Application August 20, 1954, Serial No. 451,153 Claims priority, application Germany November 30, 1953 14 Claims. (Cl. 112-242) tended to be restricted thereby save as pointed out in the claims.

An object of this invention is to provide at the be ginning of the sewing operation a sufficient length of thread for the first stitch, for instance as needed in button sewing machines. The first stitch in such machines needs to be larger than the succeeding stitches. Therefore, in order to have more thread for the first stitch, the thread will be pulled at the end of the preceding operation in accordance with the invention, so that an additional length of thread is available at the start of the succeeding operation.

A further object of the invention is to tighten th last stitch when the sewing operation is terminated preparatory for severing the thread.

Generally speaking, the invention provides for a thread pulling device, on a sewing machine with a controlled operating cycle, for instance a button sewing machine. During the customary sewing operation the thread passes through the pulling device in a straight path between a fixed thread tensioner and a fixed thread guide. When the sewing operation is terminated and therefore the sewing machine comes automatically to a stop, the pulling device will perform a twisting movement by which the thread path will no longer be straight. By this movement there is accomplished that additional thread from the button is tensioned; the thread is temporarily clamped by clamping means which form part of the pulling device.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description, taken in connection with the accompanying drawings, in which:

Fig. 1 is a fragmentary perspective view of a sewing machine having a thread pulling device in accordance with the invention, in the pulling position;

Fig. 2 is a plan view of the thread pulling device, but in the sewing position;

Fig. 3 is a sectional view taken on line 3--3 of Fig. 2; and

Fig. 4 is a perspective view of the thread pulling device viewed from below, some parts having been omitted for the sake of clarification.

In carrying the invention into eifect in the embodiment which has been selected for illustration in the accompanying drawings and for description in this specification, and referring now particularly to Fig. 1, there is provided a start switch control lever 1 of the sewing machine to which a transfer lever 2 is permanently connected. The movements of the switch lever 1 are trans mitted through thetransfer lever 2 to a crank and 2,736,989 Patented Jan. 17, 1956 to an intermediate lever 4 which, in turn, transmit the movements to a longitudinal horizontally disposed shifting rod 6. The intermediate lever 4, which has two unequal arms, is pivoted by a screw 5 to the frame of the sewing machine. The shifting rod 6 is guided for longitudinal movements in two bearings 7 and 8 of the machine frame. A dog 9 is connected to the shifting rod 6 by means of a screw 10. The dog 9 carries a pin 11 that forms a part of a cam driver 12 (Fig. 2).

Near the frame of the machine there may be put a spool S from which the thread T is pulled. The thread T reaches the needle (not shown) by way of a fixed thread guide member 40 after passing through a fixed thread tensioner 39. The instant pulling device is located between the tensioner 39 and the guide 40. The guide 40, tensioner 39 and the pulling device are provided on the cover 13 of the sewing machine (Fig. 1).

When the sewing machine is in operation, the shifting rod 6 will be in the position shown in Fig. 2, having been moved in directionA (Fig. l). The pulling device will assume the position shown in Fig. 2, and the thread will run in a straight stretch between the fixed guide member 40 and the fixed tensioner member 39, and through the pulling device that is located between these two fixed members.

As shown in Figs. 2 and 4, the thread pulling device comprises a thread deflector which includes an upper disc 22 and a lower disc 16. The lower disc 16 has a bifurcated follower 17 that engages the cam driver 12. When the sewing operation comes to a stop the shifting rod 6 will move automatically in the direction of the arrow B (Fig. l) and the cam driver 12 will move the follower 17 of the disc 16. By this movement, the disc 16 is taken along with the cam driver 12, and performs a fraction of a rotational movement in the direction D (Fig. 4).

A hollow tubular body 14 (Figs. 3 and 4) is disposed on the cover 13 of the machine, and is held thereon from below by a nut 15. The body 14 serves as a center of rotation for the discs 16 and 22. A spring 21 is wound around the body 14 and has one end connected to a pin 23 which is secured to, and projects from the underside of, the disc 22 (Figs. 2 and 4). The other end of the spring 21 is connected to a pin or screw 20 which is secured to, and extends downwardly from, the disc 16.

The outer circumference of the disc 16 has two abutment points 18 and 19 that are spaced from each other, and the pin 23 of the disc 22 projects into the space between the abutment points 18 and 19.

As shown in Figs. 1, 2 and 3, on the disc 22 there is provided clamping means 24 which comprises an upper gripping jaw 25 and a lower gripping jaw 26. The upper jaw 25 may be shorter than the lower jaw 26 for easy insertion of the thread T. A screw 27 connects the jaws 25 and 26 to the disc 22. One of the jaws, for instance the longer jaw 26 is movable, whereas the jaw 25 is fixed. A spacer bushing 28 is provided between the jaws 25 and 26 (Fig. 3).

As seen in Figs. 3 and 4, a pushing rod 29 is provided that passes through the hollow tubular body 14 and thus abuts with its upper end from below against the jaw 26 of the clamping means 24 (Fig. 3). The purpose of the pushing rod 29 is to exert at predetermined instants a momentary upward pressure onto the movable jaw 26 whereby said jaw 26 makes contact with the jaw 25 to clamp the thread. The upward pressure is obtained from a nose 43 which is carried by a rotating shaft 42 and the lower end of the pushing rod 29 rests on the surface of said shaft 42 at the point of the nose 43 thereof. A retraction spring 41 is provided that presses the rod 29 downwardly against saidsurface of the shaft 42 and acts to retract the pushing rod 29 upon release by the nose 43, in order to release the jaw 26. Upon release, the jaw 26 will assume its normal lower position, allowing a smooth passing of thethread T between the jaws 25 and 26.

On the disc 22 there are provided displacing means for the thread T. Theseinclude two radial guides 39 and 31 (Figs. 1 and 2), which are disposed at right angle to the longitudinal extension of the jaws 25 and 26 of the clamping means 24. On the guides 36 and 31 there are movably held two plates 32 and 33 that have thread guiding means, for instance slotted thread guiding pins 34 and 35 respectively. The adjustment of the plates 32 and 33 and the guides 30 and 31 is rendered possible by means of longitudinal slots 36 and 37 that are formed in the plates 32 and 33. As shown in Fig. 2, friction generating means, such as screws 33 protrude through the plates 32 and 33. In this manher, the adjustment of the pins 34 and 35 can be made independently of each other, according to the desired length of thread to be pulled.

Operation Duringthe normal sewing operation of the machine (Fig. 2), the thread T which is fed from the spool S is disposed in a straight path between the thread tensioner 39 through the clamping means 24 of the pulling device and the thread guide 40.

When the sewing machine stops, the control switch lever 1, the transfer lever 2, the crank 3, and the intermediate lever 4 will move the shifting rod 6 in the direction of the arrow B.

, The cam driver 12 of the dog 9 which is connected to the shifting rod 6 will slide in the cam follower 17 of the lower disc 16, and will turn the disc 16 in direction D from the normal position (Fig. 2) into the thread pulling position (Fig. l). The spring 21 will be taken along by the screw 20 of the disc 16. Accordingly, the upper disc 22 which is connected through the pin 23 to the other end of the spring 21 will also be taken along and performs like the lower disc 16 the rotational movement in the direction of the arrow D.

If any resistance exerted by the thread surpasses the tension force of the spring 21, the abutment point 19 will assume the function of turning the disc 22 by push- .ing the pin 23; the space between the abutment points 18 and 19 is provided to afford a time lag during which .the spring 21 may act; only upon failure of the spring to act will the point 19 take over the turning of the disc 22.

The rotational movement of the discs 16 and 22 in direction D, brings the slotted guides 34 and 35 to a position at an angle to the normal position of alignment with the normally straight path of thread between the thread tensioner 39 and the thread guide 40. By this movement, the guides 34 and 35 pull the thread olf the normal straight path and thereby there is accomplished that additional thread is pulled off the spool S, when the clamping means 24 is closed to grip the thread.

At that instant, the pushing rod 29 will be lifted by .the nose 43 against the pressure of the spring 41. The upper end of the pushing rod 29 will lift the movable lower jaw 26 of the clamping means 24 and thus will temporarily grip the thread passing between the jaws 25 and'26.

At the same time, the last stitch will be tightened because when the thread is gripped by the clamping means 24, there occurs a tension in two directions, namely one tensioning of thethread between the clamping means 24 and the spool S, and a second tensioning of the thread piece between the clamping means 24 and the article, for instance the button sewn (not shown), re-

I spectively. The latter thread tightening accomplishes another of the desired aims of the invention, namely that the thus tensioned thread can then easily be severed at the predetermined location.

The foregoing takes place as the sewing machine comes to a stop (Fig. I).

At the beginning of the succeeding sewing operation, the operator will move the shifting rod 6 in the direction A and the cam driver 12 will turn the cam follower 17 in direction C. The disc 22 will, under the tension of the spring 21 be turned by the lower disc 16 in the same direction C, and both discs 16 and 22 will assume their normal sewing position (Fig. 2).

When the disc 16 turns in direction C to assume its normal sewing position, any resistance in the path of the thread that becomes larger than the tension force of the spring 21, may tend to retard or to stop the turning of the disc 22; when this occurs, the abutment point 18 of the disc 16 will assume the role of turning the disc 22 by pushing the pin 23 in the direction C.

Simultaneously, the nose 43 will have passed beyond its peak position, and the upward force exerted on the pushing rod 29 by the nose 43 will cease, and the rod 29 will be retracted downwardly by the spring 41. Thereby the lower jaw 26 will be lowered and the thread T that was clamped temporarily between the jaws 25 and 26 be released.

After the pulling device returns to its normal position (Fig. 2), the additional thread that resulted from the previous twisting movement will be available for the larger first stitch needed to start a new sewing operation cycle.

Since certain changes may be made in the 'above article and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having thus described the invention, what I claim as new and desire to be secured by Letters Patent, is as follows:

l. A thread pulling device, for use in connection with a sewing machine with a controlled operating cycle and having automatic shifting means and a thread guide and a thread tensioner, said device comprising, a mechanism in driven connection with said shifting means and including a reciprocably rotatable member, and two opposite thread guiding elements connected to said member, said thread having a straight path between said thread tensioner and said thread guide in sewing operation and being suspended between said thread guiding elements, said mechanism being actuatable by said shifting means to turn said member and guiding elements upon termination of the sewing operation for shifting the thread from. said straight path into a path intersecting, between said guiding elements, said straight path, at an angle thereto, and clamping means operable for releasably clamping said thread between said guiding elements in timed relation with the actuation of said mechanism, whereby, upon actuation of said mechanism, said member will be turned and said clamping means will clamp the thread thereby increasing the amount of thread between said guide and tensioner.

2. A thread pulling device, for use in connection with a sewing machine with a controlled operating cycle and having automatic shifting means and a thread guide and a thread tensioner, the thread normally stretching in a straight path between said thread guide and said thread tensioner, said device comprising, a mechanism in driven connection with said shifting means and operable to turn the thread from thestraight pathbetween said thread guide and said thread tensioner into a path at an angle thereto upon termination of the sewing operaticn,'including a driving and a driven member adjacent each other and journalled for rotation about the same axis at an anglet'o said straight path, a spring connected to said members forming therebetween a resilient connection for transmission of rotary movement, thread displacing means adjustably connected to said driven member, movable clamping means connected to said driven member and operable to be closed for frictionally engaging the thread and, respectively, to be opened for thread release, and a pushing rodconcentric with said axis and passing through said members and operable to close releasably the clamping means.

3. A thread pulling device as claimed in claim 2, said thread displacing means comprising two oppositely located slotted pins operable to move under the tension of said spring the thread out of its normal straight path between said thread guide and said thread tensioner.

4. A thread pulling device as claimed in claim 2, said driven member having two longitudinal grooves, said thread displacing means comprising two oppositely located slotted pins being movable radially on said disc and operable to move under the tension of said spring the thread out of its normal straight path between said thread guide and said thread tensioner, a plate movable in each of the longitudinal grooves of said driven member, and each pin being secured to one of said plates.

5. A thread pulling device as claimed in claim 2, said driven member having two longitudinal grooves, said thread displacing means comprising two oppositely located slotted pins being movable radially on said driven member and operable to move the thread out of its nor- .mal straight path between said thread guide and said thread tensioner, a plate movable in each of the longitudinal grooves of said driven member, each pin being secured to one of said plates, and friction generating means protruding through said plates for adjusting said slotted pins independently of each other.

6. A thread pulling device as claimed in claim 2, said clamping means comprising two gripping jaws, a spacer bushing connected between said jaws, one of said gripping jaws being movably connected relative to the other jaw.

7. A thread pulling device as claimed in claim 2, said clamping means comprising two gripping jaws, a spacer bushing connected between said jaws, one of said gripping jaws being movably connected relative to the other jaw, said movable gripping jaw being below, and longer than, said fixed gripping jaw.

8. A thread pulling device as claimed in claim 2, each of said members including a projection, said spring having windings concentric with said axis, each end of said spring being connected to the projection of a member.

9. A thread pulling device as claimed in claim 2, said driving member having on its outer circumference two abutment elements spaced apart from each other, a pin connected to said driven member and protruding into the space between said abutment elements, either abutmerit element being operable to engage said pin after a time lag when the force of said spring fails to transmit {i rotational movement from said driving to said driven member during said time lag for assuring turning of said driven member with said driving member.

10. A thread pulling device as claimed in claim 2, a hollow body concentric with said axis secured on the frame of the machine and journalling said members, said pushing rod passing through said hollow body.

11. A thread pulling device as claimed in claim 2, said spring being operable to turn said driven member about said axis by being tensioned about said axis of said driving member, said driving member having a bifurcated recess forming a cam follower, a cam driver disposed in said recess, said cam driver being connected to said shifting means and operable to transmit the movements thereof to turn said driving member for tensioning said spring to turn said driven member.

12. A thread pulling device, as claimed in claim 1, said clamping means being disposed between said guiding elements and engaging in all positions said thread and normally engaging said thread slidingly, whereby said thread passes through said clamp substantially without friction and, respectively, being operable for clamping said thread to engage it frictionally to arrest it upon actuation of said mechanism.

13. A thread pulling device, for use in connection with a sewing machine having a controlled operating cycle and means for actuating said thread pulling device at the start and stop of the sewing cycle, said thread pulling device comprising a thread deflector including a disc oscillatable about its axis and having two opposite thread guides movable therewith engaging said thread normally following a straight path and operable upon turning of said disc from a rest position to move the thread from its normal straight path into a path intersecting said normal straight path, said disc including clamping means operable for releasably clamping said thread when said disc is turned from said rest position.

14. A thread pulling device, as claimed in claim 13, together with, and means intermediate said actuating means and said disc and including a spring. and operable to actuate said disc resiliently near the starting and stopping instants of the sewing machine, said resilient means being operable to be tensioned by said actuating means thereby turning said disc with the force of said tension.

References Cited in the file of this patent UNITED STATES PATENTS 540,301 Drake June 4, 1895 1,461,428 McCann July 10, 1923 1,960,924 Sailer May 29, 1934 2.300.585 McCann Nov. 3, 1942

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