JPH0671077A - Shuttle bobbin case with thread tension device - Google Patents

Abstract

PURPOSE: To provide a bobbin case having a thread tension device for guaranteeing sure bobbin thread guide without requiring any correcting operation by providing a narrow part behind the thread tension area of a thread tension spring. CONSTITUTION: The thread tension spring 19 has the largest width between both terminal parts 21 and 25, and this width is made thinner toward the top so as to be a minimum value (a) in the direction of a narrow part 30. A thread feed opening 11 linked with a thread pass slit 10 of the bobbin case 1 is provided under the narrow part 30 of a thread tension plate 19 so as to be located almost at the center of the narrow part 30. When pulling a bobbin thread from a bobbin into the bobbin case 1, the bobbin thread is passed through the thread feed opening 11, runs under the thread tension spring 19, afterwards turned along a thread guide edge 31 and guided from one side to the other side along the thread guide edge 31 corresponding to the drawing direction. The bobbin thread is slid in a tension area 43 and guided while reciprocating parallel to a winding center 7. With the operation of the narrow part 30, a fixed control power is applied to the bobbin thread by the thread tension spring 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillating looper, which is provided below a thread tension spring in a jacket and has an end face and a slit of the jacket, which are described in the superordinate concept of claim 1. A thread discharge opening for the bobbin which is pulled out from the bobbin which is connected via the thread, and which is oriented substantially parallel to the bobbin axis and is present in the front end of the thread tension spring in front of the tension and braking area. A bobbin case with a thread tension spring mounted on the jacket of a bobbin case for a sewing machine with a thread guiding edge.

[0002]

2. Description of the Prior Art Various bobbin cases are known which are equipped with a regulated thread tensioning device for the bobbin thread of a sewing machine. These bobbin cases usually consist of leaf springs fixed to the upper surface of the bobbin case jacket, the leaf springs being for adjusting the pressing force of the leaf spring on the bobbin case jacket upper surface or on the bobbin case jacket surface. Equipped with screws.

Such a thread tensioning device is described in Swiss Patent No. 43.
It is known from 5947. Depending on the characteristic asymmetrical shape of the thread tension spring, when manufacturing this thread tension spring,
There is a great deal of variation in shape accuracy and elasticity. As is known, the spring exerts a constant braking force on the thread in the pretension region defined by the alternating running direction of the thread, so that the sewing operation must be carried out so that a uniform stitch is formed. . In order to achieve this purpose, a laborious correction work is required, and this correction work can be performed only by hand. In this case, the spring tends to at least partially revert to its original shape, so that it is often necessary to carry out straightening operations several times over time. If these straightening operations are not performed or are performed with caution, the yarn will not be under constant tension. This leads to the formation of irregular stitches.

From US Pat. No. 4,884,519, another type of yarn tensioning device is known which eliminates the drawbacks of the yarn tensioning device described in the above publication. However, the yarn tensioning device disclosed in U.S. Pat. No. 4,884,519 has proven to be extremely difficult to manufacture. This is because the individual parts require extremely high precision. Therefore, the costs are correspondingly increased.

[0005]

SUMMARY OF THE INVENTION The present invention eliminates the disadvantages of the known thread tensioning device described above and requires no straightening operation, and therefore a thread tensioning device with a spring mechanism which ensures a reliable bobbin thread guide. To provide a bobbin case having a.

[0006]

The above-mentioned problems can be solved by the structure described in the characterizing part of claim 1 in which the thread tension spring is provided with a narrow portion behind the thread tension area. It

By providing the narrow portion of the thread tension spring behind the portion which is provided parallel to the bobbin axis and which acts as a braking surface, the thread tension spring is provided in the jacket surface of the bobbin case in the entire tension and braking area. It was unexpected, therefore, that it was possible to exert a constant spring force on the yarns present between them.

The region in which the tension is exerted can be corrected by a correction work in which the shape difference depending on the tolerance is minimized, and then the spring is twisted and elastically elastic so that the shape remains stable. It is connected to the rest.

Hereinafter, the present invention will be described in detail with reference to the embodiments illustrated in the accompanying drawings.

[0010]

EXAMPLE A bobbin case 1 formed in a conventional manner
Consists of an essentially cylindrical jacket 3 and a bobbin case bottom 5 with a core 7 inserted in the center. This core 7
A bobbin (not shown) serving as a lower thread storage portion is supported by the bobbin.

In the bobbin case jacket 3, a V-shaped notch 9 is formed on its open side,
This notch is connected to the yarn ejection opening 11 via a curved threading slit 10. A relatively large notch 13 is formed in the jacket 3 with a space from the yarn discharge opening 11.

A thread tension spring 19 is fixed to the bobbin case 1 by a screw 15 screwed into the jacket 3. The thread tension spring 19 has a curve slightly smaller than that of the bobbin case surface 17. The thread tension spring 19 is engaged at its rear end 21 with the holding notch 23 of the jacket 3 of the bobbin case 1. The front end 25 of the thread tension spring 19 ends in two arched parts 27, the ends 29 of these parts pointing towards each other are claw-shaped and are located in the cutout 13. It is protruding.

The arcuate portions 27 are connected to each other by a thread guide edge 31 which is essentially linearly oriented in the thread withdrawal opening 33 formed by them. The tensioning and braking area 43, which is oriented parallel to the winding core 7, is located approximately in the middle between the thread guiding edge 31 and the thread running opening 11. The passage through which the thread 37 is drawn and guided between the ends 29 remains open.

The thread tension spring 19 has the largest width in the central region, ie between the two ends 21 and 25.
This width is tapered so as to have a minimum value a in the direction of the narrow portion 30. In the illustrated embodiment, this value a corresponds to a material thickness which is about seven times that of the thread tension spring 19. This material thickness of the thread tension spring 19 is, for example, 0.25 mm and thus corresponds to a width a = 1,75 mm. The hole 35 in the thread tension spring 19 is for fixing the thread tension spring to the bobbin case 1 with the screw 15.

The thread discharge opening 11 connected to the threading slit 10 of the bobbin case 1 is provided below the narrow portion 30 of the thread tension spring 19 and substantially at the center of the narrow portion 30. . As a result, the yarn ejection opening 1
It is ensured that the running yarn 1 from 1 runs below the yarn tension spring 19 to the yarn guiding edge 31 regardless of its withdrawal direction.

In order that the thread 37 to be threaded does not remain suspended on the shoulder 32 formed by the narrowed portion 30 of the thread tension spring 19, on the side of the thread tension spring 19-in FIGS. 2 and 4. Downward reference-a thread guide web 39 is provided bridging outwardly the narrow part 30 or the constriction having a width a, which thread guide web 4 is located outwards.
Have one. The yarn guide web 39 has almost reached the tension and braking area 43.

In order to prevent the thread 37 from reaching the back of the shoulder 32 even if it is not manipulated during the threading process, the thread guide web 39 and the adjacent arches. A baffle 45 such as a labyrinth of the inner ear is provided between the shaped portions 27. This baffle essentially forms a separating slit 47 between the thread guide web 39 and the part 27 of the thread tension spring 19, in which case the arched part 27 is formed.
A tongue piece 49 is formed on the. This tongue piece 49 determines the formation direction of the separation slit 47. In this case, the parallel side edges of the tongue 49 are oriented at an obtuse angle, in particular with respect to the thread guiding edge 31.

The tension and braking area 43 on the jacket 3 of the bobbin case 1 is defined by the narrow portion 30 on the supply side. This region is formed by the upper side of the bobbin case 1, and the upper side of this bobbin case abuts the tongue side of the thread tension spring 19 in a planar contact in this region 43,
The thread tension spring is pressed against the jacket 3 by a tightening force that can be adjusted by the screw 15. The region 43 in which the tension is exerted is located approximately in the middle between the thread guiding edge 31 of the thread tension spring 19 and the narrow portion 30.

When the bobbin thread 37 is drawn into the bobbin case 1 from a bobbin (not shown), the bobbin thread 37 passes through the thread ejection opening 11, runs under the thread tension spring 19, and then follows the thread guide edge 31. It is turned over, and depending on the withdrawal direction,
The yarn is guided from one side to the other along the yarn guide edge 31. In this case, the lower thread 37 slides in the tension area 43. That is, the lower thread 37 reciprocates in parallel to the winding core 7 and is guided. The narrow portion 30 enables optimum adaptation to the changing thread running state in the tension / braking area of the tensioning portion of the thread tension spring 19, so that the thread tension spring 19 applies a constant braking force to the bobbin thread 47. It is possible to give.

[0020]

With the construction of the thread tensioning device for the bobbin case according to the present invention, it becomes unnecessary to perform elaborate correction work, and accordingly, non-uniformity of thread tension is avoided, and the thread tension is always constant. Therefore, it is possible to form a stitch having a uniform yarn.

[Brief description of drawings]

FIG. 1 is a schematic view showing a bobbin case provided with a thread tensioning device according to the present invention without incorporating a lower thread bobbin.

FIG. 2 is a plan view of the bobbin case of FIG.

3 is a cross-sectional view of the bobbin case of FIG.

FIG. 4 is an enlarged view of the thread tension spring according to FIG.

[Explanation of reference numerals] 1 bobbin case 3 jacket 13 notch 19 thread tension spring 21 one end of thread tension spring 25 other end of thread tension spring 30 narrow portion 39 thread guide web 43 tension and braking area 45 obstruction path

Claims (7)

[Claims] 1. A vibrating looper, a thread ejection opening for a bobbin drawn from a bobbin which is provided in the jacket below the thread tension spring and which is connected to the end face of the jacket through a slit, and It is mounted on the jacket of a bobbin case for a sewing machine, which is oriented substantially parallel to the axis of the bobbin and which has a thread guiding edge which lies in front of the tensioning and braking area at the front end of the thread tensioning spring. In a bobbin case equipped with a thread tension spring, the thread tension spring (1
9) is located behind the thread tension area (43) in the narrow part (3
Bobbin case characterized by having 0). 2. A thread tension zone (19) engages a rear end (21) which engages in an opening (23) in the jacket (3) of the bobbin case (1) and a notch (13). A front end portion (25), said front end portion (25) being elastically connected to the central part of the thread tension spring (19) via a narrowed portion (30). Bobbin case described in. 3. A narrowing (30) having a width (a) corresponding to a thickness (d) 5 to 10 times that of the thread tension spring (19). Bobbin case. 4. The bobbin case according to claim 3, characterized in that the width (a) corresponds to 7 times the thickness of the thread tension spring (19). 5. The thread tension spring (1) is provided in the region of the narrow portion (30).
9. The thread guide web (39) connected to the thread tension spring (19) on the side 9) is covered to form a guide edge (41).
The bobbin case according to any one of 1 to 4. 6. A portion of the thread guide web (39) which has at least reached the tensioning and braking area (43) and which exerts a tensioning action on the thread tensioning spring (19) by means of a baffle (45) such as the labyrinth of the inner ear. The bobbin case according to claim 5, wherein the bobbin case is separated from (25). 7. The bobbin according to claim 1, wherein the thread discharge opening (11) abuts the thread tension spring (19) below the narrowed portion (30). Case.