JPH0368394A - Upper yarn feeding device - Google Patents

Abstract

PURPOSE:To prevent a yarn in excessive portion from being stored around a kettle by turning OFF the second upper yarn holding device after the necessary quantity of yarn is driven out by an upper yarn driving-out mechanism and after the kettle is set at a kettle riding-over position. CONSTITUTION:When a yarn cut signal is transmitted, the first solenoid driving circuit 16 is turned OFF, and yarn drive-out control is carried out, and at the same time, a kettle riding-over timer is operated, and also after the yarn cut signal is transmitted, the second solenoid driving circuit 17 is kept in turned-ON state up to the time when a kettle passes through a kettle riding-over position. Therefore, an upper yarn in excessive portion is prevented from being pulled into the kettle.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a needle thread supply device, and particularly to a needle thread supply device that controls needle thread supply in connection with thread trimming.

[Conventional technology]

2. Description of the Related Art Conventionally, there has been known a needle thread supply device for sewing machines that supplies needle thread by turning on and off a thread holding device, as shown in FIG. 3.

In such a device, as shown in FIG. 3, the needle thread 2 from a thread supply source 1 such as a thread spool, which is a needle thread supply source, is passed through a first thread holding device 3 consisting of a solenoid, a roller 4, and a solenoid. It passes through the second thread holding device 5, is hooked onto a thread take-up 6, is threaded through the stitches of a needle 7, and is wound around a hook 21. Further, a roller amplifier solenoid 8 for pressing and releasing the roller 4 is connected to the roller 4, and a sewing material l is placed on the throat plate 9.
O! 3I, and a thread cutter 11 is attached below the throat plate 9.

FIG. 5 shows the control circuit of the above conventional device, and shows the control device (C
A thread trimming signal 13 and a thread payout amount setting device 14 for thread trimming are connected to the input side of the PU) 12, and a ROM and RA
M storage devices 15 are connected. Furthermore, the control device 1
On the output side of 2, a first solenoid drive circuit 16 for driving the first yarn holding device 3 shown in FIG.
a roller up solenoid drive circuit 18 that drives the roller up solenoid 8 that releases the motor drive control circuit 1;
A motor 20 for rotating the roller 4 is connected to the motor drive control circuit 19 .

To explain the operation of the conventional sewing machine configured in this way, in FIG. Turn on to hold and fix needle thread 2. In this state, the roller 4 that is in close contact with the upper thread 2 rotates in the direction of the arrow to let out the upper thread 2 from the thread supply source 1. When the required amount of the upper thread 2 has been let out, the first thread holding device 3 is turned on. Then, the needle thread 2 that was free is held and fixed, and the second thread holding device 'lt5 is turned off to release the needle thread 2 that was held and fixed. At this point, the thread take-up 6 rises, and the needle thread 2 that was between the roller 4 and the second thread holding device 5 is let out toward the needle 7.
Tension is applied between the first thread holding device 3 and the seam, and the seam is tightened with a predetermined strength.

Next, in the case of thread trimming, as shown in the time chart of Fig. 4, first, when the thread trimming signal 13 is turned on [Fig.
'b)], turn off the first solenoid drive circuit 16 and the second solenoid drive circuit 17 [see Figure 4 (di,
(e)], the needle thread 2 held and fixed by the first thread holding device 3 and the second thread holding device 5 is released. At the same time, in order to execute the yarn payout amount set by the yarn payout amount setting device 14, the motor drive control circuit 19 is turned on to drive the motor 20, and the roller 4 is rotated in the direction of the arrow to remove the yarn from the yarn supply source 1. Let out upper thread 2. Then, when the set amount of upper thread 2 is let out from the thread supply source 1, the first solenoid drive circuit 16 is turned on (see FIG. 4(d)), and the first thread holding device 3 moves the thread 2. to prevent the upper thread from being further unreeled from the thread supply source, and
The upper thread is cut by the thread trimmer 11, and when the thread trimming is finished, the thread trimming signal is turned off (see Part 4).

As a result, the second solenoid drive circuit 17 is turned on [see FIG. 4 (see dl), the first thread holding device 3 is released. At the same time, the upper thread holding timer in the control n device is activated (see fig. 4 + al). Furthermore, the roller up solenoid drive circuit 18 is turned on. The roller 4 holding the needle thread 2 is released.

When the time of the upper thread holding timer expires, the second solenoid drive circuit 17 is turned off to release the upper thread 2 holding the second thread holding device 5, and the upper thread becomes completely free.

In this way, when executing thread trimming, thread trimming cutter 1
1 cuts the upper thread, the first solenoid drive circuit 16 is turned off for a certain period of time, the first thread holding device 3 is released, and the second
The solenoid drive circuit 17 is turned on to cause the second thread holding device 5 to hold the upper thread. As a result, even if the object to be sewn is pulled, the needle thread 2 is restrained by the second thread holding device 5, so that the needle thread is not let out from the thread supply source.

In Fig. 4, ■ is a curve showing the relationship between the rotation angle of the hook 21 and the needle thread pull-in amount;
This is a curve showing the relationship between the lowering position and the lowering position.

[Problem to be solved by the invention]

However, in the above-mentioned device, as is clear from FIG. 4, when the thread trimming signal 13 is turned on, the hook 21 reaches the hook passing position where it pulls in the thread to the maximum. Since the second solenoid drive circuit 16, 17 is turned off and the roller 4 is driven to let out the upper thread 2 and secure the upper thread for thread trimming, the upper thread is drawn into the hook when passing through the hook. Excess thread may accumulate around the hook and get caught on the feed dog,
It gets tangled with the tip of the hook, and the needle thread becomes extremely tense when cutting it.
After that, as the thread take-up rises, the needle thread jumps up, causing the needle thread to fall out of the needle, or even if it does not come out, the amount of needle thread remaining from the needle tip decreases, and the next time, there are disadvantages such as the needle thread not being formed at the beginning of sewing. Ta.

The present invention seeks to eliminate the above-mentioned drawbacks.

[Means to solve the problem]

The needle thread supply device of the present invention has first threads spaced apart from each other that hold and fix the needle thread from the needle thread supply source. a second needle thread holding device; a needle thread letting-out mechanism that lets out the needle thread located between the second needle thread holding devices from the first needle thread holding device toward the second needle thread holding device; In the needle thread supply device, the needle thread supply device includes a hook that receives the needle thread through a needle thread take-up and a gauge needle, and a thread cutter that cuts the needle thread between the needle thread take-up and the hook below the workpiece. The present invention is characterized in that the second needle thread holding device is turned off after the required amount of thread is paid out by the feeding mechanism and after the hook reaches the hook overhang position.

[For production]

In the needle thread supply device of the present invention, even after the thread trimming signal is generated, the second solenoid drive circuit 17 remains on until the hook reaches the hook-over position, so that excess thread is less likely to accumulate around the hook. Also, excess thread is consumed when the balance is raised.

〔Example〕

The present invention will be described in detail below with reference to FIGS. 1 and 2.

In the present invention, when the thread trimming signal (see Fig. 1 Cb) is turned on, the first solenoid drive circuit 16 is turned off to perform thread payout control, and at the same time, the hook-over timer is activated and the thread trimming signal is turned on. Even after this occurs, the second solenoid drive circuit 17 continues to operate for a period T until the hook 21 passes the hook overhang position.
Leave it on. The time value T of the over-the-pot timer is
It is determined from the spindle rotation speed during thread trimming and the rotation angle of the spindle after the thread trimming signal is turned on. Alternatively, a sensor may be provided on the main shaft to generate a hook-up signal (see FIG. 1 ffl), and the second solenoid drive circuit 17 may be turned off in synchronization with this signal.

In this manner, by keeping the second solenoid drive circuit 17 in the on state until the hook reaches the hook overhang state, the second thread holding device 5 is brought into a state in which the upper thread 2 is held.

This prevents excess needle thread from being drawn into the hook when passing through the hook.

Note that the subsequent operations are the same as in the conventional example.

〔Effect of the invention〕

Since the needle thread supply device of the present invention has the above-mentioned fjI hoop, excess thread does not accumulate around the hook, so there is no risk of excess needle thread getting caught on the feed dog or getting tangled with the tip of the hook, and the thread take-up does not rise. There are great advantages in that there is no risk that the needle thread will jump up and fall off the needle, or that the amount of needle thread remaining from the needle tip will be reduced.

l thread holding device, 4... roller, 5... second thread holding device, 6... balance, 7... needle, 8... roller up solenoid, 9... needle plate, lO...Sewn object, 1
1... Thread cutter, 12... Control device (CPU
), 13... Thread trimming signal, 14... Thread payout amount setting device, 15... Memory device, 16... First solenoid drive circuit, 17... Second solenoid drive circuit, 18 ...Roller up solenoid drive circuit, 19.
...Motor drive control circuit, 20...Motor, 21...
・Kettle.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a time chart explaining the operation of the needle thread supply device of the present invention, and FIG. 2 is a flow chart,
FIG. 3 is a schematic configuration diagram of a conventional needle thread supply device, FIG. 4 is a time chart illustrating its operation, and FIG. 5 is a block diagram of a control circuit. 1... Thread supply source, 2... Upper thread, 3... Figure 1 (, d)? ;1 solenoid on (f) Over-the-pot timer”〒7゜eagle-shaped recess (e) second solenoid on

Claims (1)

[Claims] (1) First and second needle thread holding devices spaced apart from each other that hold and fix the needle thread from the needle thread supply source, and the needle thread located between the first and second needle thread holding devices a needle thread pay-out mechanism that feeds out the needle thread from the first needle thread holding device toward the second needle thread holding device; a shuttle that receives the needle thread from the second needle thread holding device through a needle thread of a thread take-up and a meter; In the needle thread supply device, which has a thread cutter that cuts the needle thread between the needle and the hook below the workpiece, the hook is in the hook over-the-hoot position and after the necessary thread amount has been let out by the needle thread letting-out mechanism. The upper thread supplying device is characterized in that the second upper thread holding device is turned off after the upper thread is reached.