JPH0768070A - Bobbin case for sewing machine - Google Patents

Abstract

PURPOSE: To improve the certainty of stitch formation in the case of starting the next sewing cycle by eliminating the danger for a bobbin thread to be dropped out of a clamp after thread cutting. CONSTITUTION: When a bobbin thread 6 is moved into the clamp, a second spring 11 can be moved to the still position of a third position. At the third position, the second spring 11 does not exert any operation upon the bobbin thread 6 in the clamp with a bobbin 16 and from this third position, the second spring 11 can be moved to a sewing position against its own elasticity by the said bobbin thread and a needle thread while the first loop of the bobbin thread and needle thread is formed at the time of starting the next sewing cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bobbin case for a multi-needle sewing machine having a thread cutting device and a clamp for fixing the bobbin thread after thread cutting, and a first spring for tensioning the bobbin thread. A second position occupying a first position as a sewing position determined by the extension state of the lower thread during the sewing process and a second position for absorbing thread slack caused by temporary stop of the needle, etc. And a bobbin case having a spring.

[0002]

2. Description of the Related Art In case of corner stitching by a multi-needle sewing machine, a needle must be stopped, but when the needle is stopped, unconsumed bobbin thread is pulled out from a bobbin. This unconsumed bobbin thread is undesirable because it causes thread slack on the back of the sewn product. Since the bobbin thread required to form the seam must be tensioned, it is necessary to remove this thread slack before restarting the stopped needle.

According to German Utility Model Registration No. 8414515, in order to keep unconsumed lower thread on the upper portion of the bobbin case of the lockstitch looper, the inner surface of the upper portion of the bobbin case is opposed to the flat inner surface of the bobbin case. It is known to provide a ring-shaped disc between the bobbin and the outer surface of the bobbin. The ring-shaped disc has a threaded hole fitting, and the threaded hole fitting can be rotated against the action of the spring, concentrically with the axis line of the lock stitch looper, and with shape restraint. The bobbin thread drawn out from the thread stocking portion is arranged around the bobbin case, and the bobbin case is tensioned to resist the bobbin thread withdrawal and the bobbin thread is tensioned. Will be guided freely by. When this metal fitting with a thread hole is used, a backward force can be applied to the lower thread. This retraction force restrains the unconsumed bobbin drawn from the bobbin under tension, forming a limited temporary stock.

A spring is arranged on the cover plate inside the upper part of the bobbin case so as to be concentric with the axis of rotation of the bobbin, and a fitting with a thread hole is provided at the free end of the spring to exert a restoring force on the bobbin thread. The upper portion of the bobbin case thus configured is also known from Japanese Utility Model Publication No. 57-21657.

Further, according to DE-A-1760559, the bobbin thread is turned in a bobbin case, which forms a restricted temporary thread storage part between the bobbin thread bobbin and the consumption position and which is provided with a tension spring. It is known to arrange a turning device for the purpose. When moving the sewn product with the needle stopped, the thread can be removed from the turning device, which returns to its home position when the thread relaxes, in which case the unspent bobbin thread is obtained.

The disadvantage of the bobbin case described above is that the lower thread is
In addition to the pulling force generated by the sewing process, the force for forming a limited temporary stock thread is always subject to an additional pulling load. Therefore, in the case of a sewing machine equipped with a thread trimming device in which the lower thread that is pulled out and cut at the cutting position is held and cut at a fixed position by the clamp, the lower thread after thread cutting is removed from the clamp. It can be accidentally pulled out and jeopardize the formation of the first stitch in the next sewing cycle.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to construct a bobbin case of a multi-needle sewing machine having a thread cutting device and a bobbin thread clamp as follows, that is, the needle is stopped. By restraining the bobbin thread that is sometimes drawn from the bobbin thread storage section and is not consumed in the sewing cycle in a tensioned state, a temporary stock thread that is limited is formed and guided to the clamp for thread trimming and fixed there. The lower thread is not loaded, and the risk of the lower thread being pulled out from the clamp is prevented.

[0008]

In order to solve the above problems, the present invention allows a second spring to move to a stationary position which is a third position when the bobbin thread moves into the clamp. , In the third position the second spring has no effect on the bobbin thread between the bobbin and the clamp, from the third position at the beginning of the next sewing cycle. It is characterized in that, while the first thread loop is formed by the lower thread and the upper thread, the lower thread and the upper thread can move to the sewing position against the elastic force of their own. .

The bobbin case according to the present invention is provided with a spring which engages with the lower thread drawn out from the thread storage section through a threaded hole fitting. The spring can be guided through the threaded fitting and moved straight to the clamp in a rest position in which it does not act on the bobbin which is fixed there.
When the bobbin thread is removed from the clamp in order to introduce it into the sewing cycle, the spring is pulled out of its rest position against its resistance by the threaded fitting. In this case, the spring exerts a force on the bobbin thread, which is greater the further the threadhole fitting is from its rest position.

With this construction, the bobbin thread that is pulled out from the bobbin when the needle is stopped and is not used for corner sewing, for example, is retained. Therefore, a limited temporary stock thread is created rather than an unwanted thread slack on the back of the sewn product. This stock thread is consumed before the bobbin is further withdrawn when the stopped needle starts sewing again.

With this construction, it is possible to use a spring which is in a relaxed state in the rest position, so that it does not exert a force on the bobbin thread which leads straight through the threaded hole fitting to the clamp. Therefore, with a simple structure, the bobbin thread after thread cutting can be prevented from coming out of the clamp. The spring is also tensioned only when the bobbin thread is removed from the clamp, thus deflecting the bobbin thread laterally.

The above-mentioned spring sufficiently satisfies the requirements for its installation space, but its shape is an open ring. This ring is fixed by one end to a cover plate provided on the bobbin case upper part so as to form a bobbin case upper part together with the side wall,
Moreover, it extends parallel to the cover plate. At the other end of the ring, a metal fitting with a thread hole for passing the lower thread is provided. The ring-shaped spring is arranged in the following way: it is arranged so that it is not pulled out of its rest position by the bobbin thread which extends straight from the bobbin to the clamp and thus exerts no force on the bobbin thread. Has been done.

It is easy to implement if the spring is arranged to be relaxed in the rest position.

With the structure described in the fifth aspect, the force acting on the lower thread can be increased. According to this structure, the spring that engages with the bobbin thread communicating with the clamp is not in a relaxed state, and is held at the stationary position by the stopper portion with which the thread hole fitting is in contact. When the bobbin thread is removed from the clamp, the pre-tensioned spring causes the bobbin thread to be deflected laterally with a greater force than in the pre-tensioned spring of embodiment 4.

A spacing element is provided between the inner surface of the cover plate and the bobbin so that the movement of the spring is not disturbed by the bobbin case during the tensioning and relaxing processes.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall perspective view of a bobbin case composed of a bobbin case upper portion 1 and a bobbin case lower portion 2. The upper part 1 of the bobbin case has a cover plate 3
(FIG. 2) and an annular side wall 4 provided perpendicularly to the cover plate 3. The side wall 4 is partially interrupted, and the side wall 4 has a guide slit 5 for the lower thread 6.
Are formed. A spring 7 is provided on the outer surface of the side wall 4. The spring 7 partially covers the guide slit 5.
The cover plate 3 protrudes beyond the outer surface of the side wall 4 to form a protruding portion 8 in the region of the side wall 4 where the guide slit 5 and the spring 7 are provided. The side wall 4 is interrupted next to the free end of the spring 7 and has a common cutting surface 9 with the protrusion 8.
have. The thread guide notch 10 penetrates into the cut surface 9 in the valley formed between the four side wall projections 8.

A spring 11 extending substantially parallel to the cover plate 3 is provided on the inner surface of the cover plate 3 (FIG. 3). The spring 11 is in the form of an open ring and in the relaxed state corresponds approximately to the curvature of the side wall 4.

One end of the spring 11 is fixed to the inner surface of the cover plate 3 with a screw 12. On the other hand, the free end of the other end has a threaded hole fitting 13. In the rest position given by the position of the relaxed spring 11, the threaded hole fitting 13 is provided in a slit 14 which is provided on the side wall 4 facing the inner surface of the cover plate 3 and which opens towards the cut surface 9. is there.

A spacing element 15 is mounted on the inner surface of the cover plate 3. The lower thread bobbin 16 comes into contact with the spacing element 15, and the spacing element 15 provides a space necessary for the lower thread 11 to move without being obstructed by the cover plate 3 and the lower thread bobbin 1.
Provided between 6 and.

The lower part 2 of the bobbin case has side wall parts 17 and 18. The side wall parts 17 and 18 engage corresponding recesses in the side wall 4 of the bobbin case upper part 1. In this case, the cutting surface 19 which comes into contact with the cutting surface 9 of the bobbin case upper part 1 has, at its free end, a projection 21 provided with a thread guide notch 20. The yarn guide notch 20 forms an outlet 22 with the yarn guide notch 10.

The side wall parts 17 and 18 of the lower part 2 of the bobbin case are located lower than that of the upper part of the bobbin case, so that the outer edge of the cover plate 3 and these side wall parts 17, 18.
There is a recess between 18. The metal fitting 13 with a thread hole pulled out from the stationary position projects to the outside through the concave portion on the extension of the slit 14.

The lower thread 6 drawn out from the lower thread bobbin 16 is
It extends toward the outlet 22 through a guide slit 5 formed in the side wall 4 of the bobbin case upper portion 1. In this case, the bobbin thread 6 is pushed toward the outer surface of the side wall 4 to be tensioned, and extends from the outer surface of the side wall 4 through the threaded hole fitting 13 to the consumption position.

FIG. 4 shows the manner in which the lower thread extends at the sewing position. The spring 11 occupies the position given at the sewing position by means of the bobbin thread 6 which is in tension with the needle and is in tension. In this case, the thread hole fitting 13
It is guided by a concave portion between the cover plate 3 of the bobbin case upper portion 1 and the side wall portion 17 of the bobbin case lower portion 2. The spring 11 exerts a force on the bobbin thread 6 and tends to deflect the bobbin thread 6 laterally.

FIG. 5 illustrates a manner in which the bobbin thread extends when the needle is stationary in corner stitching, for example. The unconsumed bobbin thread 6 drawn from the bobbin thread bobbin 16 is deflected laterally by the spring 11 to form a limited temporary stock thread. This stock thread is consumed during tensioning of the spring 11 when the needle is restarted and before further bobbin thread is drawn out of the bobbin thread bobbin 16.

When one sewing cycle is completed, the bobbin thread 6
Is brought to the cutting position. This is shown in FIG. Bobbin thread 6
Reaches the clamp 23 straight from the lower thread outlet 22 through the threaded hole fitting 13 of the spring 11. The spring 11 is in the rest position and is not tensioned. Therefore, no elastic force acts on the lower thread 6. Therefore, the bobbin thread 6 will not be accidentally pulled out from the clamp 23 after the thread cutting process.

Next, the embodiments of the present invention will be listed.

(1) The spring force of the second spring (11) acting on the bobbin thread (6) is selected so as to increase as the second spring (11) moves away from its rest position. The bobbin case according to claim 1, wherein:

(2) The shape of the second spring (11) is an open ring, which is provided at one end with the cover plate (3) in the upper part (1) of the bobbin case and at the other end. According to claim 1 or 2, characterized in that it is engaged with the lower thread (6) by means of a threaded hole fitting (13) and this ring extends substantially parallel to the cover plate (3). The bobbin case according to item 1.

(3) The bobbin case according to the above item 2, characterized in that a spacing element (15) is arranged between the bobbin (16) and the inner surface of the cover plate (3).

(4) The bobbin case according to claim 1 or any one of claims 1 to 3, characterized in that the second spring (11) is in a relaxed state in a rest position. .

(5) A stationary position of the second spring (11) is determined by a stop portion, and the second spring (11) is defined in any one of claims 1 to 4 above. Bobbin case.

(6) A metal fitting (13) with a thread hole is in contact with the stopper portion, or any one of the first to third aspects or the fifth aspect. Bobbin case described in item.

[0034]

By using the bobbin case according to the present invention, there is no risk of the bobbin thread coming out of the clamp after thread cutting. Therefore, the reliability of stitch formation when starting the next sewing cycle is improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a bobbin case according to the present invention.

FIG. 2 is a development view showing the inside of the bobbin case of FIG.

FIG. 3 is a plan view of a bobbin case according to the present invention.

FIG. 4 is a plan view of an upper portion of the bobbin case shown with a lower thread in a sewing position.

FIG. 5 is a plan view of the upper portion of the bobbin case shown with the lower thread displaced during corner sewing.

FIG. 6 is a plan view of the upper portion of the bobbin case shown with the lower thread in the thread cutting position.

[Explanation of symbols]

 1 bobbin case upper part 2 bobbin case lower part 6 bobbin thread 7 first spring 11 second spring 16 bobbin 23 clamp

 ─────────────────────────────────────────────────── ——————————————————————————————————————————————————————————————————————————————————————————————— 6750 Kaiser Slautern Karl Puff Gitling 12

Claims (1)

[Claims] 1. A bobbin case for a multi-needle sewing machine comprising a thread trimming device and a clamp for fixing a lower thread after thread trimming,
A first spring for tensioning the bobbin thread, a first position as a sewing position determined by the extension state of the bobbin thread during the sewing process, and a slack of the thread caused by a temporary stop of the needle, etc. In the bobbin case having a second spring occupying a second position for absorbing, the second spring (11) has a lower thread (6) clamped (23).
A second position (3) in which the second spring (11) is moved between the bobbin (16) and the clamp (23). 6) has no effect on the second spring (1
1) is the elastic force of the third thread from the third position at the start of the next sewing cycle and while the first thread loop is formed by the lower thread and the upper thread. A bobbin case that can be moved to a sewing position against.