JPH0549776A - Needle thread holding device in sewing machine - Google Patents

Abstract

PURPOSE:To reduce noise during operation of a thread guard member and to ensure a needle thread suspended from a sewing needle by suitably setting the timing of the operation. CONSTITUTION:A thread guard member 94 is moved from its standby position to an extended position thereof by rotating a control motor 102, and a needle thread Y suspending from a sewing needle 68 is hooked by a hook part of the member 94 which are then returned to its original standby position so that the leading end of the needle thread is led into an opening 82 of a thread hold member 80. Accordingly, the leading end of the needle thread is held at the position of the thread holding member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for holding, above a sewing needle, a thread end of a needle thread that is thread-cut and hangs down from a sewing needle after sewing such as embroidery is finished in a sewing machine.

[0002]

2. Description of the Related Art As a needle thread holding device of this type, for example, a technique disclosed in Japanese Patent Laid-Open No. 59-211487 can be mentioned. In this publication, a thread holding member is provided in the lower part of the sewing machine head (needle bar case), and a thread hooking member is arranged at the back of the thread holding member. Based on the drive of the rotary solenoid, the thread hooking member is provided with a sliding operation of protruding directly below the sewing needle at the top dead center and returning from that position to the original standby position.

The thread hooking member slides as described above by the driving of the rotary solenoid, and the needle thread hanging from the sewing needle is hooked by thread cutting to guide the thread end into the opening of the thread holding member. As a result, the thread end of the upper thread is held by the thread holding member.

[0004]

SUMMARY OF THE INVENTION In the technique disclosed in the above publication,
Since the rotary solenoid is used as the drive source of the thread hooking member, a large noise is generated when the thread hooking member is operated, which is one of the causes of noise generation of the sewing machine.

A technical problem to be solved by the present invention is to reduce the noise when the thread hooking member is operated, and to secure an appropriate length of the upper thread remaining on the sewing needle side after thread cutting depending on the setting of the operation timing. Is.

[0006]

In order to solve the above problems, the needle thread holding device of the present invention is constructed as follows. That is, by vertically moving a needle bar having a sewing needle at its lower end, sewing is performed by the upper thread passed through the sewing needle and the lower thread under the needle plate, and after this sewing is completed, the upper thread under the needle plate. In the sewing machine to be cut, the thread end of the needle thread which is arranged at a position substantially corresponding to the top dead center of the sewing needle and which hangs from the sewing needle after the thread cutting is introduced into the opening portion of the sewing needle. A thread holding member capable of holding the thread end, and a hook portion capable of hooking an upper thread hanging from a sewing needle at the tip, and a standby position where the hook portion is located at the back of the thread holding member, Similarly, the thread hooking member arranged so as to reciprocate through the opening of the thread holding member between the hook position and the projecting position located immediately below the sewing needle at the top dead center, and the thread hooking member is on standby. Reciprocating between position and protruding position And a control motor that.

[0007]

According to the above construction, the thread hooking member is actuated from the standby position to the projecting position by the rotational drive of the control motor, so that the hook portion of the thread hook member hooks the needle thread hanging from the sewing needle. be able to.
Then, the yarn end of the upper yarn is pulled into the opening of the yarn holding member by returning the yarn hooking portion to the original standby position.
As a result, the thread end of the upper thread is held at the position of the thread holding member, that is, at a position substantially corresponding to the top dead center of the sewing needle.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to the drawings. In the following examples, the needle thread holding device of the present invention is applied to a multi-needle type sewing machine.

FIG. 1 is a side sectional view of a sewing machine head 10, and FIG. 2 is a front view thereof. In these drawings, the sewing machine head 10 includes a sewing machine arm 12 fixed to the sewing machine frame 2 and a needle bar case 50 assembled to the front surface of the sewing machine arm 12 so as to be slidable in the width direction thereof.

A sewing machine spindle 14 is attached to the sewing machine arm 12.
The needle bar drive member 44 shown in FIG. 1 is vertically driven in association with the rotation of the sewing machine main shaft 14. A balance drive motor 26 is attached to the upper portion of the sewing machine arm 12. A sector gear 28 is fixed to a drive shaft 27 of the motor 26, and the sector gear 28 is reciprocally rotated by driving the motor 26.

On the other hand, the needle bar case 50 is provided with a plurality of needle bars 60 arranged along the sliding direction thereof so as to be vertically movable. The sewing needles 68 are attached to the lower ends of the respective needle bars 60.
Moreover, each needle bar 60 is provided with a cloth retainer 70,
It is assembled so as to follow the vertical movement of 0. On the axis of each needle bar 60, a needle bar holder 62 having a protruding pin 64 engageable with the needle bar drive member 44 is fixed.

Further, on the shaft of the balance shaft 22 fixed to the upper part of the needle bar case 50, as many balances 20 as the needle bars 60 are provided.
Is supported so as to be rotatable around the axis of the balance shaft 22. A gear 21 that can mesh with the sector gear 28 is formed on the boss portion of each balance 20.

By sliding the needle bar case 50, one needle bar 60 and one balance 20 corresponding thereto are selected. The selected needle bar 60 is driven up and down by engaging the protruding pin 64 of the needle bar holder 62 with the needle bar drive member 44. The gear 21 of the selected balance 20 meshes with the sector gear 28, and is rotated (balance operation) in synchronization with the vertical movement of the needle bar 60 based on the drive of the balance drive motor 26.

Next, a device for holding the upper thread after the thread is cut after sewing is described. First, the needle bar case 5
A thread holding member 80 is attached to the lower part of 0 so as to be located on the back side of each needle bar 60. This thread holding member 80
Is provided at a position substantially corresponding to the top dead center of the sewing needle 68, and has a slit-shaped opening 82 over the range of each needle bar 60.

On the other hand, a support plate 90 is fixed to the side surface of the sewing machine arm 12 together with the motor bracket 100 with bolts 91. The support plate 90 has a mounting portion along the side surface of the sewing machine arm 12 and a supporting portion that is bent integrally with the mounting portion along the inclination of the lower surface of the sewing machine arm 12. A guide body 92 that supports the thread hooking member 94 so as to be slidable back and forth between the support portion and the support portion is attached to the lower surface of the support portion. A pulse motor 102 as a control motor is attached to the motor bracket 100. These configurations are shown in perspective view in FIG.

The thread hooking member 94 is located on the back portion corresponding to the needle bar 60 selected by sliding the needle bar case 50, and a hook portion 96 for hooking the thread is formed at the tip thereof. .. Moreover, this thread hook member 94
Is an arm portion 98 that extends laterally from a portion near its base end portion.
Is equipped with. The tip of this arm 98 is the guide body 9
2 protrudes outward from the side portion, and the connecting piece 98a is bent and formed there.

The thread hooking member 94 can reciprocate (slide) between a standby position shown by a solid line in FIG. 1 and a projecting position also shown by a virtual line in FIG. At the standby position, the hook portion 96 of the thread hooking member 94 is located at the back of the thread holding member 80, and at the protruding position, the hook portion 96 is located immediately below the sewing needle 68 at the top dead center, and between them. In the thread hooking member 94, the thread holding member 8
0 through the opening 82.

One end of a rotary lever 105 is fixed to the drive shaft 104 of the pulse motor 102, and the other end of the rotary lever 105 is connected via a link 106 to the thread hooking member 9.
4 is connected to the connecting piece 98a of the arm portion 98. Therefore, by the rotation of the drive shaft 104 of the motor 102, the sliding operation is given to the thread hooking member 94 through the operation of the rotating lever 105 and the link 106.

The return spring 108 shown in FIGS. 1 and 2 functions to return the thread hooking member 94 to the standby position at all times. This return spring 1
08 is essentially unnecessary because the thread hooking member 94 is driven by the pulse motor 102. However, when the pulse motor 102 is open-loop controlled, it becomes uncontrollable if step out occurs due to overload, and therefore the return spring 108 is provided for the purpose of preventing this.

Further, in this embodiment, the control for turning off the drive current and the holding current to the pulse motor 102 at the last moment of the backward movement control of the thread hooking member 94 is performed. Therefore, the thread hooking member 94 after that is in a completely free state, and is returned to its standby position by the elastic force of the return spring 108. As a result, even if the step-out occurs in the control, one step of the reciprocating operation of the thread hooking member 94 always corrects the step-out amount.

In the above structure, the sewing needle 68 of each needle bar 60
The upper thread Y that has passed through the hole at the tip of the balance 20 corresponding to each thread is inserted in each. And the selected needle bar 6
It is well known that the sewing operation is performed by the upper thread Y and the lower thread (not shown) by the above-described operation of 0 and the balance 20.

When the predetermined sewing is completed, a jump signal is input to drive the needle bar 60 and a drive signal is input to the pulse motor 102. This jump signal interrupts the drive transmission from the needle bar drive member 44 to the needle bar 60, and the needle bar 60 is held at its top dead center. On the other hand, the pulse motor 102 receives the drive signal immediately after the sewing needle 68 of the needle bar 60 comes out of the cloth (needle hole of the needle plate),
The drive shaft 104 is rotationally controlled. Based on this, the thread hooking member 94 slides to the projecting position as shown in FIG. 4 (A). In this state, the needle thread Y between the sewing needle 68 and the needle plate 110 is located on the hook portion 96 of the thread hooking member 94.

Subsequently, as shown in FIG. 4B, the thread hooking member 94 is returned toward the standby position by a predetermined stroke. As a result, the needle thread Y is hooked on the hook portion 96 and pulled obliquely upward, and the thread length left on the sewing needle 68 side is secured after thread cutting in the next step. The securing of the thread length of the upper thread Y has hitherto been dependent on the function of a hooking claw (picker) provided below the needle plate 110. However, the thread length secured by this hooking claw was unstable, but in the present embodiment, the desired thread length can be secured depending on the operation timing of the thread hooking member 94 shown in FIG. It can be abolished and the number of parts can be reduced.

Next, below the needle plate 110, the upper thread Y is thread-cut by the cooperation of the movable blade and the fixed blade of the automatic thread cutting mechanism. At this time, the thread hooking member 94 slides again toward the protruding position in accordance with the movement of the movable blade, as shown in FIG. 4 (C). As a result, the tension of the upper thread Y is relieved, and unexpected thread breakage of the upper thread Y due to contact with the fixed blade is prevented. In the state of FIG. 4C, the upper thread Y is cut.

After thread cutting, as shown in FIG. 4D, the thread hooking member 94 is returned to the standby position. As a result, the upper thread Y hanging from the sewing needle 68 is guided into the opening 82 of the thread holding member 80 by the hook portion 96. A tape having a plurality of fine loop fibers is attached to the inner surface of the opening portion 82, and the yarn end of the needle thread Y drawn therein is held by being entwined with the loop fiber.

[0026]

As described above, according to the present invention, by using the control motor as the drive source of the thread hooking member, the acceleration / deceleration at the time of driving the thread hooking member can be set at a desired timing.
No impact noise is generated unlike when a conventional rotary solenoid is driven, and the length of the upper thread remaining on the sewing needle side after thread cutting can be set to an appropriate length depending on the setting of the operation timing.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a sewing machine head.

FIG. 2 is a front view showing a sewing machine head.

FIG. 3 is a perspective view showing an upper thread holding device.

FIG. 4 is an explanatory diagram in which the operation of the upper thread holding device is made to correspond to part of FIG. 1.

[Explanation of symbols]

 60 Needle bar 68 Sewing needle 80 Thread holding member 82 Opening 94 Thread hooking member 96 Hook portion 102 Motor Y Upper thread

Claims (1)

[Claims] 1. A needle bar having a sewing needle at its lower end is driven up and down to sew with an upper thread passed through the needle and a lower thread under the needle plate, and after the sewing is completed, the needle plate is sewn. In the sewing machine in which the upper thread is cut below, the thread end of the upper thread, which is arranged at a position substantially corresponding to the top dead center of the sewing needle and hangs from the sewing needle after the thread cutting, is guided to its opening. It has a thread holding member that can hold this thread end by inserting it, and a hook part that can hook the upper thread hanging from the sewing needle at the tip, and this hook part is located at the back of the thread holding member. A thread hooking member arranged so as to reciprocate through the opening of the thread holding member between the standby position and the protruding position where the hook portion is located just below the sewing needle at the top dead center; The hanging member between its standby position and its protruding position A needle thread holding device in a sewing machine, comprising: a control motor that reciprocates.