JPH067678U - Needle thread length adjusting device for sewing machine - Google Patents

Abstract

(57) [Summary] [Purpose] At the beginning of sewing of the sewing machine, even if the upper thread end of the needle is set to an appropriate length so that a so-called bird's nest does not occur, the thread pulls out from the needle at the start of needle drop. Try not to. [Structure] A thread dragging means provided in a needle thread path between the thread take-up needle and the sewing needle to increase the length of the needle thread from the balance to the sewing needle by threading the needle thread during the thread trimming operation. It is composed of a drive source of the thread dragging means and a control means of this drive source, and the thread dragging means operates during the thread trimming operation so that the needle thread length between the thread take-up needle and the sewing needle is a predetermined amount. This is a needle thread length adjusting device for a sewing machine in which the length of the needle thread end of the sewing needle is appropriately maintained to prevent the thread from slipping out when seen from the needle thread at the beginning of sewing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 This invention maintains an appropriate length of the upper thread end of the sewing needle by allowing a margin for the upper thread length from the balance to the sewing needle while sewing is completed and thread trimming is performed. Further, the present invention relates to a needle thread length adjusting device in a sewing machine, which prevents the thread from slipping out when viewed from the needle thread at the start of sewing.

[0002]

[Background of device]

 It is well known that if the upper thread end of the sewing needle is too long, the end of the upper thread is entangled at the beginning of sewing to form a so-called bird's nest, which significantly impairs the quality of the sewn product. To prevent this, the upper thread end that is locked by the sewing needle may be shortened.

However, if the upper thread end is adjusted to an appropriate amount, that is, to such an extent that the bird's nest does not occur, a phenomenon occurs in which the upper thread end comes out of the sewing needle at the beginning of sewing. This thread pull-out phenomenon is caused by a combination of thread pull-up of the balance at the beginning of sewing, lowering of the sewing needle with respect to the needle thread which is in a semi-fixed state by the thread tension regulator, and inertial force of the thread.

In order to prevent the thread from slipping off, a technique of grasping the upper thread end of the sewing needle at the beginning of sewing is disclosed. However, this technique is designed to prevent the thread from slipping out at the beginning of sewing by grasping the tip of the upper thread protruding from the sewing needle near the sewing needle, and the shorter the upper thread from the sewing needle, the more the device. Has to be placed very close to the sewing needle, and there is a drawback in that it hinders the sewing operation depending on the type of sewn product.

[0005]

[Outline of the device]

 This device is designed to increase the length of the upper thread from the balance to the sewing needle by striking the upper thread during the thread trimming operation, which is provided in the upper thread path between the balance and the sewing needle. From the means, the drive source of the thread drawing means, and the control means of the drive source,

Alternatively, a plurality of such thread dragging means are provided, and a thread holding means for holding the upper thread draped by the thread dragging means at a predetermined position, a drive source of this thread holding means, and a control of this drive source. It is an object of the present invention to solve the above-mentioned conventional problems by providing a means to configure a needle thread length adjusting device in a sewing machine.

[0007]

[Action]

 During the thread trimming operation, the thread threading means operates to increase the needle thread length between the balance and the sewing needle by a predetermined amount, and this increase or slack amount causes the balance to rise at the start of sewing and the sewing needle to move. This will cancel the pulling of the upper thread due to lowering, etc., and as a result, even if the length of the upper thread end of the sewing needle is set to an unsuitable proper length that does not cause so-called bird's nest, The tip of the needle thread will not come off.

[0008]

[Example of device]

 An embodiment of the present invention will be described with reference to the drawings. 1 and 2 are views showing an embodiment of the present invention. In FIG. 1, 1 is a sewing machine head, 2 is a balance, and 3 is a sewing needle. Reference numeral 4 denotes a link mechanism interposed between the yarn guides 5 and 51 and the rotary solenoid 6 as a drive source, and the link mechanism 4 and the yarn guides 5 and 51 constitute a yarn drawing means. The link mechanism 4 is composed of a first rotating link 4a, a first link 4b, a second rotating link 4c, and a second link 4d.

Reference numeral 7 is a thread pressing mechanism, and 8 is a link mechanism interposed between a solenoid 9 as a drive source. The thread pressing mechanism 7 and the link mechanism 8 constitute a thread pressing means. The link mechanism 8 is composed of a first link 8a, a rotating link 8b, and a second link 8c. In addition, 10 is an upper thread in the upper thread path from the balance 2 to the sewing needle 3.

FIG. 2 is a perspective view showing the details of the thread guides 5 and 51 and the thread pressing mechanism 7. As shown in the figure, the thread guides 5 and 51 are each formed of a wire rod and have a quadrangular frame at the tip. 5a and 51a are integrally provided, and the upper thread 10 is captured by these frame bodies 5a and 51a. The rear ends of the thread guides 5 and 51 are fixed to the first rotation link 4a that constitutes the above-mentioned link mechanism 4.

The thread pressing mechanism 7 is composed of an oscillating body 7a integrally formed at the end of the above-mentioned first link 8a, a fixed body 7b, and a rubber plate 7c as a slip stopper. Slits are formed on both opposite sides of the U-shaped fixed body 7b so that the rocking body 7a can move back and forth in the slit, and further on the surface facing the rocking body 7a. A rubber plate 7c is stretched so that the upper and lower threads 10 are pressed by both.

Although the control means for the rotary solenoid 6 and the solenoid 9 as the drive source are not shown, the control means is composed of a microcomputer or the like and corresponds to the thread trimming signal in the thread trimming operation at the end of sewing. It is designed to control the drive of each drive source.

The operation of this embodiment will be described based on the above configuration. When the sewing operation is completed and the needle thread is first pressed in the thread trimming device, the rotary solenoid 6 is rotated clockwise like an arrow by the control signal of the control means output corresponding to the thread trimming signal. . Therefore, the second rotating link 4d moves leftward in the figure, the second rotating link 4c rotates clockwise around the shaft 4c1, and the first link 4b moves rightward in the figure. Accordingly, the first rotation link 4a rotates counterclockwise about the shaft 4a1. Along with this, the frame bodies 5a and 51a of the thread guides 5 and 51 rotate from their original positions to the positions of a and b while rotating as shown by the arrows to hold the needle thread 10, respectively. A predetermined amount, that is, a thread length corresponding to the amount of pulling up the upper thread of the balance 2 at the start of sewing, the amount of pulling down the upper thread of the sewing needle 3 and the like is pulled out from the needle thread supply source (not shown) to obtain the balance 2 and the sewing needle 3. Will increase the needle thread length between.

When the frame bodies 5a and 51a move to the positions a and b, respectively, and when the predetermined amount of the upper thread 10 has been traversed, the solenoid 9 starts to operate by the output of the drive control signal from the control means. The second link 8c moves to the left in the figure, which causes the rotating link 8b to rotate clockwise about the shaft 8b2 against the biasing spring 8b1, so that the first link 8a moves to the right in the figure. As a result, the upper thread 10 is held between the rocking body 7a and the rubber plate 7c.

When the yarn pressing operation by the oscillating body 7 a is completed, the rotary solenoid 6 starts rotating again from the position so far, and returns the yarn guides 5, 51 to the original position via the link mechanism 7. Then, the next sewing operation starts and the solenoid 9 is switched off at the same time when the sewing needle 3 starts to descend, and the oscillating body 7a is returned to its original position via the link mechanism 7 by the urging force of the urging spring 8b1 to release the thread presser. It will be canceled.

Thus, at the start of the sewing operation, the needle thread 10 in the needle thread path from the balance 2 to the sewing needle 3 corresponds to the upper thread pull-up amount of the balance 2, the upper thread pull-up amount of the sewing needle 3, and the like. This means that the length to be hit is provided as a slack or a margin. Therefore, if sewing is started in this state, the thread pull-out phenomenon does not occur even if the needle thread end of the sewing needle 3 is shortened to the extent that a so-called bird's nest does not occur.

In the above-described embodiment, an example in which two thread pulling means are provided and the thread holding means is further provided between these thread pulling means has been described. However, a single thread pulling means is installed, Even if the yarn pressing means is not provided, a certain effect similar to the above can be expected.

[0018]

[Effect of device]

 As described above, according to this invention, the thread threading means is activated during the thread trimming operation to increase the needle thread length between the balance and the sewing needle by a predetermined amount, and this increase or slack amount is Since the needle thread is pulled up when the balance is raised and the sewing needle is lowered at the beginning of sewing, the length of the needle thread at the sewing needle is set to an appropriate length that does not cause so-called bird's nest. Even when set to, the needle thread tip does not come off from the sewing needle, and sewing quality and sewing efficiency are greatly improved.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of a main part of the above.

[Explanation of symbols]

 1 sewing machine head 2 balance 3 sewing needle 4 link mechanism} thread drag means 5, 51 thread guide 6 drive source (rotary solenoid) 7 thread holding mechanism} thread holding means 8 link mechanism 7a rocking body 7b fixed body 7c rubber plate 9 drive source (Solenoid) 10 Upper thread

Claims (2)

[Scope of utility model registration request] 1. A thread dragging means provided in the needle thread path between the balance and the sewing needle to increase the length of the needle thread from the balance to the sewing needle by striking the needle thread during the thread cutting operation. , Consisting of a drive source of this thread dragging means and a control means of this drive source, and the thread dragging means is activated during the thread cutting operation to increase the needle thread length between the thread take-up needle and the sewing needle by a predetermined amount. By doing so, the needle thread length adjusting device in the sewing machine is configured to properly maintain the length of the needle thread end of the sewing needle and prevent the thread from slipping out when viewed from the needle thread at the beginning of sewing. 2. The yarn pressing means according to claim 1, further comprising a plurality of thread dragging means, for holding the upper thread dragged by the thread dragging means at a predetermined position, a drive source for the thread pressing means, and this drive. A needle thread length adjusting device in a sewing machine, characterized in that a source control means is provided to hold the drawn upper thread between the end of thread cutting and the next needle drop.