JP3107866B2 - Needle thread holding device in sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for holding a thread end of an upper thread which is cut off after sewing such as embroidery in a sewing machine and is hanging from a sewing needle above the sewing needle.

[0002]

2. Description of the Related Art An example of such a needle thread holding device is a technique disclosed in Japanese Patent Application Laid-Open No. Sho 59-211487. In this publication, a thread holding member is provided at a lower portion of a sewing head (needle bar case), and a thread hooking member is arranged at the back of the thread holding member. Based on the driving 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 the position to the original standby position.

[0003] The drive of the rotary solenoid causes the thread hooking member to slide as described above, hook the upper thread hanging from the sewing needle by thread cutting, and guide the thread end into the opening of the thread holding member. Thereby, the yarn end of the upper thread is held by the yarn holding member.

[0004]

According to the technique disclosed in the above publication,
Since a rotary solenoid is used as a drive source for the thread hooking member, the sound generated when the thread hooking member operates is large, which contributes to the generation of noise of the sewing machine.

[0005] The technical problem of the present invention can reduce the sound during the operation of the yarn hooking member Rutotomoni, can ensure upper thread remaining on the needle side sewing after thread cutting depending on the setting of the operation timing to an appropriate length And open loop control motor
In case of control, step-out occurs due to control overload.
Even if the thread hooking member makes a single reciprocating operation, it always compensates for the step-out.
Is to make it possible .

[0006]

In order to solve the above problems, the needle thread holding device of the present invention is configured as follows. That is, sewing is performed by the upper thread passed through the sewing needle and the lower thread under the needle plate by the vertical drive of the needle bar having the sewing needle at the lower end, and after the completion of the sewing, the upper thread is moved below the needle plate. In the sewing machine where the sewing needle is cut, the thread end of the upper thread hanging from the sewing needle after the thread trimming is introduced into the opening of the sewing needle at a position substantially corresponding to the top dead center of the sewing needle. A thread holding member capable of holding a thread end, a hook portion capable of hooking an upper thread hanging from the sewing needle at the tip, and a standby position in which the hook portion is located on the back of the thread holding member; A thread hooking member arranged so as to reciprocate through an opening of the thread holding member between a hook portion and a protruding position located immediately below a sewing needle at a top dead center, and waits for the thread hooking member. I will return to the position
And a control motor for reciprocating the thread hooking member between its standby position and the projecting position. And this control motor
Control to stop the supply current during the return control of the
Is controlled.

[0007]

According to the above construction, the upper thread hanging from the sewing needle is hooked at the hook portion of the thread hooking member by operating the thread hooking member from the standby position to the projecting position by the rotational drive of the control motor. Can be. The thread end of the upper thread is pulled into the opening of the thread holding member by returning the thread hooking portion to the original standby position. Thus, 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. And the thread hook
Stop supply current to control motor during material return control
So that the subsequent threading members are
Always return to the standby position by the turn spring. This
When the control motor is set to open loop control
Even if step-out occurs due to control overload, the thread hook
The step-out is always corrected by one reciprocating operation.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. In the following embodiment, the needle thread holding device of the present invention is applied to a multi-needle sewing machine.

FIG. 1 shows a sewing head 10 in a side sectional view, and FIG. 2 shows 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 slidably attached to a front surface of the sewing machine arm 12 in a width direction thereof.

The sewing machine arm 12 has a sewing machine main shaft 14 attached thereto.
The needle bar drive member 44 shown in FIG. 1 is driven up and down in conjunction with the rotation of the sewing machine main shaft 14. A balance drive motor 26 is mounted on the upper part 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 reciprocates 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 so as to be vertically movable. The sewing needle 68 is attached to the lower end of each of the needle bars 60.
In addition, each needle bar 60 is provided with a cloth presser 70,
It is assembled so as to follow the vertical movement of 0. On the shaft of each needle bar 60, a needle bar holder 62 having a protruding pin 64 engageable with the needle bar driving member 44 is fixed.

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

One needle bar 60 and one corresponding balance 20 are selected by sliding the needle bar case 50. The selected needle bar 60 is driven up and down by the projection pin 64 of the needle bar holder 62 engaging with the needle bar driving member 44. The selected balance 20 has its gear 21 meshed with the sector gear 28, and rotates (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 description will be given of a device for holding the upper thread after the sewing and the thread cut. First, the needle bar case 5
A thread holding member 80 is attached to a lower portion of the needle bar 0 so as to be located on the back side of each needle bar 60. This thread holding member 80
Are arranged at positions substantially corresponding to the top dead center of the sewing needle 68 and have slit-shaped openings 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 with bolts 91 together with the motor bracket 100. 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 threading member 94 so as to be able to slide back and forth between the support and the support is attached to the lower surface of the support. A pulse motor 102 as a control motor is mounted on the motor bracket 100. These configurations are shown in perspective in FIG.

The thread hooking member 94 is located at the back corresponding to the needle bar 60 selected by sliding the needle bar case 50, and a hook 96 for hooking a thread is formed at the tip thereof. . Moreover, this thread hooking member 94
Is an arm 98 extending laterally from a position near the base end thereof.
It has. The tip of the arm 98 is the guide 9
2 protrudes out from the side, where the connecting piece 98a is bent.

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

One end of a rotation lever 105 is fixed to the drive shaft 104 of the pulse motor 102, and the other end of the rotation lever 105 is connected to the thread hooking member 9 via a link 106.
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 rotation lever 105 and the link 106.

The return spring 108 shown in FIGS. 1 and 2 functions to always return the thread hooking member 94 to the standby position. This return spring 1
08 is not necessary since the thread hooking member 94 is driven by the pulse motor 102. However, if the pulse motor 102 is in open-loop control and loses synchronism due to overload, control becomes impossible, and the return spring 108 is provided to prevent this.

Further, in the present embodiment, the control for turning off the driving current and the holding current to the pulse motor 102 at the last moment of the return control of the yarn hooking member 94 is performed. Therefore, the subsequent thread hook member 94 is completely free, and returns to its standby position by the elasticity of the return spring 108. Thus, even if the control loses synchronism, the loss of synchronism is always corrected by one reciprocating operation of the thread hooking member 94.

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

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. The 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 a drive signal immediately after the sewing needle 68 of the needle bar 60 comes out of the cloth (the needle hole of the needle plate),
The rotation of the drive shaft 104 is controlled. Based on this, the threading member 94 slides to the projecting position as shown in FIG. In this state, the upper thread Y between the sewing needle 68 and the needle plate 110 is located at the hook 96 of the thread hooking member 94.

Subsequently, as shown in FIG. 4B, the thread hooking member 94 is returned by a predetermined stroke toward the standby position. As a result, the upper thread Y is hooked on the hook portion 96 and is pulled obliquely upward, so that the thread length left on the sewing needle 68 after thread trimming in the next step is secured. Until now, the securing of the thread length of the upper thread Y has relied on the function of a hooking claw (picker) provided below the needle plate 110. However, the thread length secured by this hook claw was unstable. However, in this embodiment, a desired thread length can be secured depending on the operation timing of the thread hooking member 94 shown in FIG. It can be eliminated to reduce the number of parts.

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

After the thread is cut, as shown in FIG. 4D, the thread hooking member 94 is returned to the standby position. Thus, the upper thread Y hanging from the sewing needle 68 is led into the opening 82 of the thread holding member 80 by the hook 96. A tape having a plurality of fine loop fibers is affixed to the inner surface of the opening 82, and the thread end of the upper thread Y drawn in here is held entangled with the loop fibers.

As described above, in the needle thread holding device of this embodiment,
Therefore, the acceleration and deceleration of the thread hooking member 94 can be set to a desired timing, there is no impact sound unlike when a conventional rotary solenoid is used as a drive source, and the sewing needle 68 is cut after thread trimming.
Can be adjusted to an appropriate length. Ma
Even if the motor 102 loses control,
The step-out is always corrected by one reciprocating operation of the member 94.

[Brief description of the drawings]

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

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

FIG. 3 is a perspective view showing a needle thread holding device.

FIG. 4 is an explanatory view showing the operation of the upper thread holding device corresponding to a part of FIG.

[Explanation of symbols]

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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) D05B 65/06 D05B 65/02

Claims (1)

(57) [Claims] 1. A needle bar provided with a sewing needle at a lower end thereof is driven up and down to perform sewing by an upper thread passed through the sewing needle and a lower thread below a needle plate. In the sewing machine in which the upper thread is cut below, the sewing machine is disposed at a position substantially corresponding to the top dead center of the sewing needle, and guides the thread end of the upper thread hanging from the sewing needle to the opening after cutting the thread. A thread holding member capable of holding the thread end by inserting the needle thread, and a hook portion capable of hooking an upper thread hanging from the sewing needle at a tip thereof, wherein the hook portion is located at the back of the thread holding member. a standby position, the yarn hooking member similarly hook portion is arranged to reciprocate through the opening of the yarn holding member between a projecting position located directly below the sewing needle is at the top dead center, the yarn A function that returns the hook member to the standby position. Over
Comprising a down spring, and a control motor for similarly reciprocate between a protruding position the yarn hooking member and its standby position, the control motor, subjected during backward movement control of the yarn hooking member
An upper thread holding device in a sewing machine, which is controlled so as to stop a supply current .