JPH0345672B2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a sewing machine in which the necessary amount of needle thread required for sewing one stitch is supplied to the thread take-up side, thereby achieving a good stitch. .

Prior Art The supply of needle thread in a sewing machine is normally performed by the needle thread pay-out action of a thread take-up, and the amount of needle thread drawn out is determined according to the change in the amount of frictional resistance applied to the needle thread by a tension plate device. The adjustment of the adjustment plate device was performed while checking the seams visually.

However, in recent years, theoretical research on sewing has progressed, and quantitative evaluations have been made that the thread consumption for a good seam is set in relation to the sewing conditions, especially the fabric thickness and sewing pitch. To get a good seam,
The idea that it is sufficient to control the amount of needle thread consumed has emerged. That is, when sewing, the fabric thickness and sewing pitch are first detected by a sensor, the sewing machine's built-in microcomputer calculates the amount of needle thread required for the seam, and then the thread take-up is controlled by some mechanical or electrical means. The idea of automating sewing adjustment to supply the necessary amount of upper thread has been emerging.

For example, the upper thread is guided from the upper thread bobbin through the base tension disc between a roller attached to the step motor shaft and a thread presser roller facing the roller, and the appropriate amount of upper thread is controlled by pulse control of the step motor. There are devices that actively feed yarn into a thread take-up device, but with such devices, when the yarn is fed out in a large amount and at high speed, the inertia becomes large, and the required self-starting frequency becomes extremely large. ,
Sewing thick materials requires high cloth tightening tension, so the step motor needs to have a large restraint torque to counter the cloth tightening force of the thread take-up.The motor specifications are high performance and large capacity, making it expensive in terms of cost. There are practical difficulties.

Purpose of the present invention is to feed and supply needle thread required for each stitch for each stitch, and to allow the thread take-up to perform only a cloth tightening action without performing a thread feeding action, thereby achieving good stitching. The object of the present invention is to provide a device which can supply a needle thread to a sewing machine using a simple configuration with less inertia.

Configuration The present invention supplies the needle thread amount required for one stitch to the thread take-up side by means of a needle thread feed-out roller that feeds out the needle thread in cooperation with a driven presser roller, and the supply amount is controlled. By stopping the supply by gripping the upper thread of the electromagnetic upper thread gripper, the upper thread is slipped between the upper thread pay-out roller and the driven presser roller, and during the cloth tightening action by the thread take-up, the upper thread is stopped by the electromagnetic upper thread gripper. The needle thread gripping force is used to hold the needle thread without being pulled out.Hereinafter, the present invention will be described with reference to embodiments shown in the drawings.

Fig. 1 is a perspective view of a sewing machine head according to the present invention, Fig. 2 is a plan view showing a schematic configuration of an automatic stitch tension control device provided on the sewing machine head, and Fig. 3 is a partially sectional view of the sewing machine head. FIG. 4 is a sectional view showing an example of an electromagnetic needle thread gripper.

The sewing machine head A is equipped with a sewing needle 1, a thread take-up lever 2, and needle thread guides 3, 4, and 5 for sewing the suture cloth B, but there is no tension plate and the needle thread is inserted into the thread take-up side. The upper thread feeding roller 6 and the presser roller 7 which rotates as a result of the upper thread feeding are moved by a lever 8 with a spindle 9 as a fulcrum and a spring 10 to move the upper thread into the upper thread feeding roller 6.
is pressed against the needle thread pay-out roller 6.
is adapted to be driven by the main shaft 11 of the sewing machine. Since this is to change the needle thread payout speed in accordance with the sewing machine operating speed, it may be driven by a motor that rotates in synchronization with the sewing machine operating speed. It is necessary to provide an encoder for detecting the yarn running amount on the upper thread supply side of the upper thread paying-out roller 6, but in this embodiment, the upper thread paying-out roller 6 and the encoder 6a for detecting the thread running amount are coaxially integrated. Generally, it is provided in the form of a yarn feeding roller with a built-in encoder. Furthermore, an electromagnetic needle thread gripper 1 is provided on the needle thread supply side of the thread running amount detection encoder 6a.
2. A base tension plate 13 is provided,
The upper thread C, which is pinched and let out from the upper thread bobbin 14 by the presser roller 7 and the upper thread pay-out roller 6, is given a weak tension by the base tension plate 13 so as not to disturb the thread, and the electromagnetic upper thread gripper 12 While it is not excited, it is guided by guides 5, 4, and 3 and supplied to the balance side.

By the way, in the present invention, the upper thread unwinding gripping force by the upper thread unwinding roller 6 and the presser roller 7 is smaller than the gripping force when the electromagnetic upper thread gripper 12 is energized. When the upper thread is gripped by the thread take-up roller 12, the upper thread is not let out because the upper thread is only held down by the presser roller 7 so that it rotates idly without letting out the upper thread. During the cloth tightening action, the upper thread is configured to be held and fixed by the electromagnetic upper thread gripper.

Next, the operation of the sewing machine will be explained.

When the sewing machine is driven to sew cloth, the needle thread pay-out roller 6 rotates, and the needle thread, which is pressed and held between the presser roller 7 and the needle thread bobbin 1, is rotated.
4, the thread begins to be supplied to the thread take-up lever 2 side through the base tension plate 13 and the electromagnetic upper thread gripper 12 which is in an inactive state. When the thread running amount detection encoder 6a detects that the needle thread of the length required for sewing one stitch is fed out, which has been detected in advance, the electromagnetic needle thread gripper 12 is energized to grip the needle thread. This causes the needle thread paying-out roller 6 to stop feeding out the needle thread, thereby causing the needle thread paying-out roller 6 to idle.
Then, when sewing the cloth, the upper thread supplied to the thread take-up side is applied with tension by the thread take-up 2 to tighten the cloth and form a good seam. While the thread take-up is tightening the cloth, the upper thread is held and fixed by the electromagnetic upper thread gripper 12.

After the thread take-up 2 finishes tightening the fabric, the electromagnetic needle thread gripper 12 is de-energized, the continuously rotating needle thread feed roller 6 restarts feeding the needle thread, and the first stitch is sewn in the same way. After the required amount of needle thread is let out, the electromagnetic needle thread gripper 12 is operated to idle. In addition, in the figure, the reference numeral 15 is a cover.

Effects As explained above, according to the present invention, the amount of needle thread required for one stitch can be supplied to the thread take-up side by
This is done by a constantly rotating needle thread pay-out roller.
After the required feeding has been performed, the electromagnetic needle thread gripper grips the needle thread to create a sliding condition between the needle thread feeding roller and the needle thread, and the needle thread feeding roller is constantly rotated. The thread feeding mechanism has almost no inertia, and can reliably supply the required amount of upper thread even during high-speed operation.In addition, it is equipped with an upper thread feeding roller, a presser roller, an encoder for detecting the amount of thread traveling, and an electromagnetic needle thread gripper. A simple configuration is sufficient.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a sewing machine head according to the present invention, Fig. 2 is a plan view showing a schematic configuration of an automatic stitch tension control device provided on the sewing machine head, and Fig. 3 is a partially sectional view of the sewing machine head. FIG. 4 is a sectional view showing an example of an electromagnetic needle thread gripper. DESCRIPTION OF SYMBOLS 1... Sewing needle, 2... Balance, 3, 4, 5... Guide, 6... Needle thread pay-out roller, 6a... Encoder for detecting thread travel amount, 7... Presser roller, 8... Lever, 9... ...Spindle, 10...Spring, 12...Electromagnetic thread gripper, 13...Base tension plate, 14...
...Needle thread bobbin, A...Sewing machine head, B...Sewing fabric, C...Needle thread.

Claims (1)

[Scope of Claims] 1. A base tension disc, an electromagnetic thread gripper that grips and releases the needle thread being fed, and an encoder for detecting the amount of thread traveling in the needle thread path that is supplied from the needle thread bobbin to the thread take-up thread. , and a needle thread pay-out roller equipped with a driven presser roller that presses and clamps the upper thread is installed on a shaft that is driven by or synchronized with the main shaft of the sewing machine and is always in a rotating state when the sewing machine is running, and when the upper thread is tensioned by the thread take-up. During the period other than that, the maximum required amount of needle thread required for one stitch in the sewing machine is configured to be able to be supplied to the thread take-up side by the needle thread pay-out roller, so that the required amount for one stitch in actual sewing work is When the needle thread is fed out, an electromagnetic thread gripper is activated to grasp the needle thread, thereby bringing the needle thread into a sliding engagement state with the feeding roller and stopping the needle thread supply. Automatic sewing tension control device. 2. A needle thread travel amount detection encoder is provided on the needle thread pay-out roller shaft, and the needle thread supply amount is detected by the encoder.
2. The automatic sewing tension control device according to claim 1, wherein the automatic sewing tension control device starts with a grip release signal of the electromagnetic upper thread gripper and ends with a grip signal of the electromagnetic upper thread gripper.