JPS58159788A - Control system of sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control system for a sewing machine, and particularly to a control system for a sewing machine that is capable of sewing a predetermined number of stitches.

Conventionally, there has been a device shown in FIG. 1 that implements this food control method. In FIG. 1, a pedal 10 serving as a braking mechanism for stopping or braking the sewing machine and a stitch count setting device 12 are connected to a microcomputer (hereinafter referred to as MPU) 14. Speed control circuit (hereinafter referred to as 80
16 (referred to as U) controls the speed of the drive motor 18 of the sewing machine based on commands from the MPU 14. The driving force of this motor is transmitted to the sewing machine 22 via the power transmission member 20. The detector 24 generates the vertical position and speed detection signals of the needle 26 of the sewing machine 22 and sends them to the MPU 14 and 5O.
This is to be supplied to U16.

Next, the operation of the apparatus that executes the conventional control method having the above configuration will be explained. When the pedal 1o is depressed, the MPU 14 inputs the set number of stitches to the stitch number setting device 12 and at the same time gives a command to the IqOU 16 to start operation, so that the torque of the motor 18 is transmitted to the sewing machine 22 and the sewing machine starts rotating. start.

On the other hand, the MPU 14 receives the needle up position signal from the detector 24 and subtracts the set number of stitches stored internally. Variable speed operation is performed using the pedal 10 until the set number of stitches is counted up, but at the same time as the count up, the MPU 14
By outputting a low speed command to control the temotor 18, the rotation of the sewing machine 220 is locked at a low speed and then stopped with a predetermined accuracy of placing the needle in the upper or lower position.

FIG. 2 is a characteristic diagram showing the state from the start of operation to the stop after count-up when the number of stitches is set l, where the horizontal axis is time and the vertical axis is the number of revolutions. In FIG. 2, it is assumed that the speed during the variable speed operation period is high, but in reality, even an intermediate speed from low to high speed can be set by the amount of depression of the pedal 10.

In this case, the number of stitches is controlled by the MPU 14 in FIG.
- As shown in the chart, the speed of the sewing machine 22 is locked to a low speed after counting up and stopped at a predetermined needle position, so the actual number of stitches is always m stitches less than the set number of stitches. There will be more. In addition, n in Fig. 3 is the number of stitches,
In the initial state, n-1,l is the set number of stitches, and up is the needle up position signal.

Since the conventional sewing machine control system is configured as described above, the set number of stitches does not match the actual number of stitches, and the set number of stitches has to be set lower by m as shown in Figure 2. was there.

The present invention has been made in view of the above-mentioned conventional problem, and its purpose is to reduce the speed of the sewing machine before the set number of stitches counts up by changing the MPU control program. To provide a control method for a sewing machine that can match the actual number of stitches.

To achieve the above object, the present invention provides a drive mechanism for driving a sewing machine and a control 41 for stopping or braking the sewing machine! A control device that operates the sewing machine at a variable speed from a predetermined low speed to a high speed by controlling the drive mechanism and braking mechanism described above, and a signal that detects the vertical position and speed of the sewing machine needle. In a sewing machine equipped with a detector for generating waste and a stitch number setting means, in order to form the set number of stitches, during operation of the sewing machine, before finishing sewing the set number of stitches,
The sewing machine is characterized in that the timing at which the speed of the sewing machine is lowered to a predetermined speed is variable.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings. The configuration of the apparatus for executing the control method of the present invention is shown in FIG. 4 and is exactly the same as that shown in FIG. 1.

In the conventional device, the MPU 14 issues a low speed command after counting up the set number of stitches, and after confirming that the speed has become low, the control program is created so that the device stops at a predetermined position. As shown in FIG. 5, the control program for the MPU 14 is modified so that a low speed command is output to the 5OU 16 before the needle counts up.
At the time of count-up, the sewing machine 22 is already rotating at a low speed that can ensure sufficient stopping accuracy. Therefore, an extra stitch of m needles as shown in FIG. 2 is not formed. In addition, in FIG. 5, n, 1. up and 5top are the same as in FIG. 3, and k is a constant 1≦ and ≦n.

Similar to FIG. 1, the variable speed operation portion in FIG. 4 is set at high speed, but any speed from low to high speed is also possible depending on the amount of pedal depression.

Figure 6 is a characteristic diagram showing the state from the start of operation to the stop after counting up when the set number of stitches is 0, and the horizontal axis is time;
The vertical axis is the rotation speed. As is clear from the figure, the present invention outputs the low speed command before the count-up, but the brake characteristics of the motor 18, etc.
Due to differences in the speed of the sewing machine and the sewing machine load before the count-up, it is possible that the speed of the sewing machine 22 may not have fallen to the low speed at the time of the count-up even if the low-speed command is outputted k stitches ago. In that case, an extra m stitch of stitches as shown in FIG. 2 is formed. In such a case, it is possible to provide an external switch and change the value of k to make adjustments so that no extra stitches are formed.

In the above embodiment, the control method of the present invention was realized by changing the program of MP[J14, but it can also be realized using discrete parts.

As described above, according to the present invention, the control method for forming stitches according to the set number of stitches is realized by changing the control program of the MPU, so that the device that executes the control method of the present invention can be made at low cost. This has the effect of obtaining highly accurate products.

[Brief explanation of drawings]

Figure 1 is a block diagram showing a device that executes the conventional sewing machine control system, Figure 2 is a characteristic diagram showing the state of operation from start to stop using the conventional sewing machine control system, and Figure 3 is a diagram of the conventional sewing machine control system. 70- of MPU stitch count processing in control method
Chart diagram, FIG. 4 is a block diagram showing a device that executes the control method of the present invention, FIG. 5 is a flowchart of MPU stitch count processing according to the sewing machine control method of the present invention, and FIG. 6 is a diagram showing the sewing machine control method of the present invention. FIG. 3 is a characteristic diagram showing the state of operation of the sewing machine from start to stop. Identical members in each figure are given the same reference numerals; 10 is a pedal; 1 is a pedal;
2 is a stitch number setting device, 14 is an MPU, 16 is a sewing machine, and 24 is a detector. Agent: Patent Attorney Shin Kuzuno - (1 other person): Figure 2, Figure 6, Figure 3! Figure 5

Claims (1)

[Claims] (1) A drive mechanism for driving the sewing machine, a braking mechanism for stopping or braking the sewing machine, and by controlling the above drive mechanism and braking mechanism, the sewing machine can be controlled from a predetermined low speed to a high speed. To form a set number of stitches in a sewing machine equipped with a control device for variable speed operation, a detector for generating a sewing machine needle vertical position signal and a speed detection signal, and a stitch number setting means. A control method for a sewing machine characterized in that the timing for reducing the speed of the sewing machine to a predetermined speed before the sewing machine finishes sewing a set number of stitches during operation of the sewing machine is made variable.