JPH03149092A - Sewing machine control device - Google Patents

Abstract

PURPOSE:To obtain a control device rather free from inching by providing a manual operation setting means for a gain value to control the operation of an electric motor in such a way as to stop the motion of a needle at the predetermined position from the detection start point of a needle position detec tor. CONSTITUTION:The operation of a pedal causes an instruction signal generation means to output a signal for stopping a sewing machine to a control circuit 7, thereby braking an electric motor 4. When the rotational speed of the sewing machine and the electric motor 4 is high, the machine and the motor 4 pass the required stop position. When a stop position signal is detected with a posi tion detector 9 after the speed drops to a level allowing a stop at the predeter mined position, the rotation of the motor 4 is controlled and stopped with the control circuit 7 for stopping at the aforesaid stop position. This stop control is regulated with a gain value K for a manual setting means comprising resistors R1 to R4 and a switch 12. With the gain value K selected with the switch 12, the control cir cuit 7 controls the speed of the motor 4 until stopping. The stop position is so kept as to give the predetermined angle by setting the pulse count value of an encoder signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a sewing machine mainly used for industrial purposes.

[Conventional technology]

Industrial sewing machines driven by electric motors are often equipped with a control device that automatically stops the sewing machine needle in the upper or lower position.

This control device consists of a position detector that detects the vertical position of the sewing machine needle, an encoder that detects the rotational speed of the motor, instruction signal generating means such as a pedal that indicates the operating speed of the motor and the needle stop position, and a control circuit. Equipment motors used include DC motors, synchronous motors, induction motors,
Brushless electric motor etc. are used.

In the old days, mechanical brakes were used to keep sewing machine needles in fixed positions vertically. Recently, electric brakes such as dynamic braking of electric motors have been used to stop objects in a fixed position. Unlike mechanical brakes, electric brakes have the problem of the electric motor pulsating when stopping. This rhythm refers to the fact that the motor cannot stop at the stop position all at once, but instead stops temporarily before the stop position and then slowly turns and stops at the stop position, or it goes too far past the stop position and then returns to the stop position and stops. Note that as a conventional method, there is Japanese Patent Publication No. 63-66555.

[Problem to be solved by the invention]

The present invention addresses the above-mentioned problem of rhythm, and its object is to provide a control device for a sewing machine with extremely little rhythm.

The present invention includes a main body of a sewing machine, an electric motor that drives the sewing machine, a control circuit that controls rotation of the electric motor, and a drive circuit that drives the electric motor according to instructions from the control circuit.
An encoder that outputs a rotation signal based on the rotation of the electric motor, an encoder rotation signal processing circuit that processes the encoder rotation signal that is taken into the control circuit, and a needle position detector that outputs the needle position signal of the sewing machine needle that is taken into the control circuit. and instruction signal generation means for generating instruction signals for rotating, stopping, etc., the electric motor, which are incorporated into the control circuit. fl7i
When the motor is stopped, the speed of the motor is controlled based on a value obtained by multiplying the speed difference between the indicated rotational speed of the instruction signal generating means and the actual rotational speed by a predetermined gain value. A control device for a sewing machine is provided with a manual gain value setting means for controlling the operation of the electric motor so that movement of the sewing machine needle stops at a predetermined position from a starting point.

[Effect]

A manual gain value setting means is provided to adjust the motor operation control so that the sewing machine needle stops at a predetermined position.
A state with less rhythm can be selected by adjusting the manual setting means.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows an outline of the sewing machine. 1 is the sewing machine body,
2 is the needle of the sewing machine, 3 is the pulley of the sewing machine, 4 is the electric motor, 5
is the pulley of motor 4. A belt 6 is installed between a pulley 3 of a sewing machine and a pulley 5 of an electric motor 4. electric motor 4
The rotation of is transmitted to the sewing machine body 1 via the belt 6. 7 is a control circuit. 8 is an encoder that measures the rotational speed of the electric motor. 9 is a position detector that detects the needle position of the sewing machine. By detecting the position of the pulley 3 of the sewing machine with the position detector 9, it is possible to detect the vertical position of the needle 2. When pulley 3 rotates once,
Pulley 3 and needle 2 are synchronized so that needle 2 makes one reciprocation. encoder 8.

The device is controlled by a position detector 9, a control circuit 7 that receives an output signal from a pedal instruction signal generating means, and the like.

Figure 2 shows the drive control circuit of the electric motor.
Puls width Modulation
). This electric motor 6 is a brushless motor, but a DC motor may also be used. Q1 to Q6 are transistors, and D1 to D6 are diodes. The driving frequency of transistors Q1 to Q6 is 2 K FI z ”
It is around 10KHz. Transistor Q * ”Q
P/N control is performed by changing the on time of the base drive signal a.

PWM that changes the duty D of the voltage applied to the motor
In control, duty D is expressed by the following equation.

D==K(N-NREF) K Gain N: Actual speed N F: Increasing the value of command speed gain K (gain) increases the value of duty D, so the response of the motor becomes faster. Conversely, lowering the gain value will slow down the response. This responsiveness particularly affects acceleration and deceleration of the motor. Although deceleration is performed by reverse braking, it is also possible to use dynamic braking. In dynamic braking, as the speed decreases, the ys power becomes weaker, so it is desirable to shift to reverse braking when the rotational speed decreases.

In order to stop the sewing machine needle 2 at a fixed position (predetermined position), the electric motor is braked while its speed is controlled. The position sensor controls the speed from the start of detection until it stops.

If this speed control during braking is not performed well, the sewing machine needle 2 will not stop smoothly at a predetermined position.

There is a rhythm when it stops, where it goes too far and returns, or stops short and then moves slightly until it reaches a predetermined position. This rhythm is the sewing machine body 1. This seems to occur when the characteristics of the load consisting of the pulleys 3, 5, belt 6, etc. and the speed control of the motor are not matched. Therefore, a feature of the present invention is that in a motor that performs speed control using PWM control, the value of the gain K (gain) is adjusted so that the motor can be stopped at a predetermined position where no rhythm occurs.

FIG. 3 is a block circuit diagram showing the main parts of the sewing machine control device. The control circuit 7 is composed of a microcomputer and corresponds to a central control section. The drive control circuit 10 for the electric motor 4 has a configuration as shown in FIG.

The drive control circuit 10 is capable of performing PWM control for changing the on-time of the brushless motor 6 upon receiving a base drive signal of the transistor Q x =Q e from the control circuit 7 .

The encoder signal of the encoder 8 outputted by the rotation of the electric motor 6 is taken into the control circuit 7 via the signal processing circuit 11. This signal processing circuit 11 processes the -encoder signal so that it matches the control circuit of the microcomputer.

A pedal (not shown) for operating the sewing machine is equipped with an instruction signal generating means. When the pedal is depressed forward, a forward depression signal is output from the instruction signal generating means. By increasing the amount by which the pedal is depressed forward, an instruction signal is output that increases the rotational speed of the electric motor 6. By pressing the pedal backwards.

A reverse pedal signal is output. The pedal is depressed forward and backward with a neutral point in between, and is configured to automatically return to the neutral point when the pedal stops being depressed. When the pedal returns to the neutral position from the forward-depression state, an instruction signal to stop the sewing machine needle 2 in the lower position is output.

When the pedal is reversely depressed from the neutral point, an instruction signal to stop the sewing machine needle 2 at the upper position is output.

When the pedal, which has been in the forward-depressed state, is suddenly turned into the reverse-depressed state, an instruction signal is output that causes the sewing machine needle 2 to stop at the upper position, as in the previous example. In this case, the sewing machine needle 2 appears to stop at the lower position and then stops at the upper position. The instruction signal output from the instruction signal generating means is taken into the control circuit 7, and the sewing machine is controlled as described above. Signals indicating the upper and lower positions outputted from the position detector 9 as the sewing machine is operated are taken into the control circuit 7.

Gain K configured by resistors R1 to R4 and switch 12
The manual setting means (gain value) is connected to the control circuit. The gain K is selected by closing the contacts corresponding to each resistor.

Next, the operation will be explained.

When the front pedal is pressed forward and the front pedal signal output from the instruction signal generating means is input to the control circuit 7, the control circuit 7 outputs a drive signal to the transistor of the drive control circuit 10.

The drive control circuit 10 is activated in response to this drive signal, and the operation of the electric motor 6 is controlled. As the amount of forward depression of the pedal increases, the amount of the forward depression signal output from the instruction signal generating means increases. This increases the rotational speed of the electric motor 6.

The speed of the sewing machine is controlled by adjusting the amount by which the pedal is pressed forward.

The encoder 5 attached to the rotating shaft of the electric motor 6
Since it rotates together with the rotation of the encoder, an encoder signal is output. The encoder signal is processed by the signal processing circuit 11 and input to the control circuit 7.

It is desirable to increase the resolution by quadrupling the encoder signal in the signal processing circuit 11.

By measuring the signal from the encoder 5 with the control circuit 7, the actual speed of the electric motor 6 can be known. When the actual speed is lower than the speed instructed by the instruction signal generating means, the control circuit 7 controls the motor 7 to increase its speed so as to reach the instructed speed. On the other hand, when the speed is higher than the commanded speed of the command signal generating means, the control circuit 7 controls the speed to reduce the speed so that the motor reaches the commanded speed.

When the pedal in the front-depression state is returned to the neutral state, the front-depression signal of the instruction signal generating means changes from ON to OFF. This OFF
In response to the signal, the control circuit 7 instructs and controls the electric motor 6 to suddenly stop. The braking of the electric motor 6 is controlled so that the sewing machine needle 2 comes to the lower position and stops. The lower position signal of the position detector 9, which is synchronized with the up and down reciprocation of the sewing machine needle 2, is ONL.

At this point, the rotation of the electric motor 6 is controlled to stop.

The center points of signal generation at the upper and lower positions of the position detector 9 are set at a rotation angle of 30° from the top dead center and bottom dead center of the sewing machine needle 2, respectively. The detection angle of the position signal of the position detector 9 is approximately 35° to 45°. The detection angle of the position signal may be centered at a point 30 degrees past the top and bottom dead centers.

When the pedal, which is in the forward-depressed state, is suddenly turned into the reverse-depressed state, the instruction signal generating means operates as follows. first.

When the pedal reaches the neutral point, the front pedal signal changes from ON to OFF, and immediately after this, the pedal shifts to the reverse pedal state, so the reverse pedal signal changes from OFF to ON. The control circuit 7 receives the forward pedal and reverse pedal signals.

The electric motor 6 is instructed to stop suddenly, and the braking is controlled so that the sewing machine needle 2 comes to the upper position and stops. In this braking stop, the electric motor 6 is controlled to stop the sewing machine needle 2 at the lower position, and then moves the sewing machine needle 2 to the upper position and stops.

When you stop pressing the pedal, it automatically becomes neutral.

When the pedal is in the neutral state, the lower part of the sewing machine needle 2 remains at the upper position. When the sewing machine needle 2 is in the lower position, perform the pedal movement.

The rotation of the electric motor 6 is controlled to move the sewing machine needle 2 to the upper position and then stop it. However, when the sewing machine needle 2 is in the upper position, the sewing machine needle 2 remains as it is even if the pedal is operated. The electric motor 6 is not rotated.

When stopping the sewing machine needle 2 in operation at the upper position, or when moving the sewing machine needle 2 at the lower position to the upper position and stopping it, the electric motor 6 moves in the sewing direction of the sewing machine needle 2.
turns and stops.

The reason why the electric motor 6 rotates in the reverse sewing direction and stops is because when the sewing machine needle 2 is stopped, when the sewing machine needle 2 passes the stop position, the electric motor 6 rotates in the opposite direction and returns to the stop position.

When the sewing machine needle 2 is in the lower position, when the instruction signal generating means outputs an ON reverse pedal signal by operating the pedal, the sewing machine needle 2 moves to the upper position and stops. At this time, the sewing machine needle 2 does not move up and down repeatedly, but only performs a semi-reciprocal movement from the lower position to the upper position.

From the perspective of the rotation of the pulley 3, the electric motor 6 will stop if only half a rotation is taken.

The position detector 9 that detects the upper and lower positions of the sewing machine needle 2 has a detection angle of 30° to 45' as a position signal detection angle, but this is not suitable for adjusting the needle stop position.

An arbitrary position can be selected by adjusting the angle at which the position detector 9 is attached to the sewing machine main body 1.

The stopping operation of the sewing machine needle 2 will be explained in more detail.

When the pedal is operated, a signal to stop the sewing machine is input from the instruction signal generating means to the control circuit 7, and the electric motor 6 is braked. If the rotational speed of the sewing machine and electric motor 6 is high, it will pass the predetermined stop position.If the rotational speed of the sewing machine and electric motor 6 is low enough to stop at the predetermined stop position, and then the stop position signal is detected by the position detector 9, the The rotation of the electric motor 6 is controlled and stopped by the control circuit 7 so that it remains at the stop position.

This stop control is controlled by a gain K (gain value) of a manual setting means consisting of resistors R.1 to R4 and a switch 12.

By the gain K (gain value) selected by the switch 12,
The control circuit 7 controls the speed of the electric motor 6 until it is stopped.The pulse count of the encoder signal is set so that the stop position is at a predetermined angle (vertical stop position II of the sewing machine needle 2). This is done by Fourth
The figure shows a flowchart of the control circuit 7 related to speed control to the stop position. That is, when the vehicle reaches the stop position, the designated speed is determined using a predetermined method, and the actual speed is calculated from the encoder signal. The output duty is determined by multiplying the difference between the commanded speed and the constant speed by a set gain K (gain value). The speed is controlled based on this result, and the pulses of the encoder signal are counted to stop the motor at a predetermined position.

The duty D in PWM control for forward and reverse rotation of the electric motor 6 changes depending on the gain K (gain value). This gain is related to the rotation of the electric motor 6 and the responsiveness during braking. By adjusting the gain (gain value) to match the load characteristics of the sewing machine main body 1 and the transmission section, the sewing machine needle 2 can be stopped at a predetermined position without inching.

FIG. 5 is a graph showing the relationship between position detection, instruction signals, and rotational state during braking. This will be explained. As the amount of pedal depression of the sewing machine during operation is decreased, the rotational speed N of the electric motor 6 decreases. When the pedal becomes neutral, the pre-depression signal of the instruction signal generating means changes from ON to OFF, and the electric motor 6 further decelerates. For example, when the lower position signal (ON) of the position detector 9 is output when the rotation speed has decreased to the point at which the sewing machine needle 2 reaches the lower position, the electric motor 6 stops when the sewing machine needle 2 reaches the lower position. It will be done.

At this time, when the pedal is depressed in the opposite direction, a reverse depression signal (ON) is output from the instruction signal generating means, so the electric motor 6 rotates again, and when the sewing machine needle 2 reaches the upper position, the position detector 9 detects the upper A position signal (ON) is output, and the electric motor 6 is stopped according to an instruction from the control circuit 7.

In this way, the electric motor 6 rotates, gi4 moves, and stops. Number of revolutions N! When following the operating curve shown in , there is no inching and the motor stops.

Rhythm occurs during the operating curve indicated by the rotational speeds Nz and Na. At N2, a movement is performed in which the robot stops before the upper position, moves a little, and then stops. At N3, after passing the upper position, the movement is reversed, returns to the upper position, and stops.

When Nz, gain K (gain value) by manual setting means
The adjustment is made so that no inching occurs.

When Nz and Na, the gain K (gain value) is not adjusted, so it is necessary to adjust the settings of the manual setting means to eliminate inching.

〔Effect of the invention〕

As described above, the present invention includes a main body of a sewing machine, a motor that drives the sewing machine, a control circuit that controls the rotation of the motor, a drive circuit that drives the motor according to instructions from the control circuit, and a motor that drives the sewing machine. an encoder that outputs a rotation signal based on the rotation of the encoder, an encoder rotation signal processing circuit that processes the encoder rotation signal that is taken into the control circuit, and a needle position detector that outputs a needle position signal of the sewing machine needle that is taken into the control circuit. , instruction signal generation means for generating instruction signals for rotating, stopping, etc. of the electric motor, which are taken into the control circuit, and when the electric motor is stopped, a predetermined speed difference between the instruction rotation speed and the actual rotation speed of the instruction signal generation means is provided. The speed of the electric motor is controlled based on the value obtained by multiplying the gain value of the sewing machine, and the operation of the electric motor is controlled so that the movement of the sewing machine needle stops at a predetermined position from the detection start point of the needle position detector. A control device for a sewing machine is characterized in that it is provided with a manual gain value setting means.

According to this configuration, the manual setting means can adjust the gain value (gain K) taken into the control circuit of the electric motor to stop the sewing machine needle at a predetermined position without causing the electric motor to pulsate.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a schematic diagram of a sewing machine, Fig. 2 is a drive control circuit diagram of an electric motor, Fig. 3 is a block circuit diagram showing main parts of a sewing machine control device, and Fig. FIG. 4 is a flowchart showing the operation of the electric motor, and FIG. 5 is a graph showing the relationship between position detection, instruction signals, and rotational state during braking. 1...Sewing machine body, 2...Sewing machine needle, 7...Control circuit, 4...Electric motor, 8...-Encoder, 9...-
position detector. Fig. 1 111 F/ Fig. 2 Fig. 3 (1,6 O Oyo 121 Fig. 4 [Start] f f 1:y; H degree (NIEF) 1!1
E: (ru I j I, it:W;, y (慴j l l≦01

Claims (1)

[Claims] 1. A main body of a sewing machine, an electric motor that drives the sewing machine,
A control circuit that controls the rotation of this electric motor, a drive circuit that drives the electric motor according to instructions from this control circuit, an encoder that outputs a rotation signal according to the rotation of the electric motor, and a rotation signal of the encoder that is taken into the control circuit. A rotation signal processing circuit for the encoder to be processed, a needle position detector that outputs the needle position signal of the shimin needle that is taken into the control circuit, and an instruction signal generator that generates instruction signals such as rotation and stop of the electric motor that are taken into the control circuit. and a needle for controlling the speed of the motor based on a value obtained by multiplying the speed difference between the indicated rotational speed and the actual rotational speed of the instruction signal generating means by a predetermined gain value when the motor is stopped. 1. A control device for a sewing machine, characterized in that said gain value manual setting means is provided for controlling the operation of a motor so that movement of a sewing machine needle stops at a predetermined position from a detection start point of a position detector. 2. A control device for a sewing machine according to claim 1, characterized in that a needle position detector for detecting an upper position and a lower position is used. 3. A control device for a sewing machine according to claim 2, characterized in that the movement of the needle is stopped at a position slightly past the top dead center and bottom dead center of the needle that moves up and down. 4. The main body of the sewing machine, the electric motor that drives this sewing machine,
A control circuit that controls the rotation of this electric motor, a drive circuit that drives the electric motor according to instructions from this control circuit, an encoder that outputs a rotation signal according to the rotation of the electric motor, and a rotation signal of the encoder that is taken into the control circuit. A rotation signal processing circuit of an encoder to be processed, a needle position detector that outputs a needle position signal of a sewing machine needle that is taken into a control circuit,
It is equipped with an instruction signal generating means that generates an instruction signal for rotating or stopping the electric motor, which is taken into the control circuit, and when braking to stop the electric motor, a predetermined speed difference between the instruction rotation speed and the actual rotation speed of the instruction signal generation means is provided. The speed of the electric motor is controlled based on the value obtained by multiplying the gain value.The main body of the sewing machine is equipped with a rotating main shaft, and a crank mechanism is provided to convert the rotation of the main shaft into the up and down reciprocating movement of the sewing machine needle. Manual setting of the gain value for controlling the operation of the motor so that the movement of the sewing machine needle stops at a predetermined position from the detection start point of the needle position detector in a machine in which the rotating main shaft and the electric motor are connected via a rotation transmission means. A control device for a sewing machine, characterized in that a means is provided, an encoder is attached to the electric motor, and a needle position detector is attached to the sewing machine body for detecting the rotation of a rotating main shaft of the sewing machine body to detect the upper and lower positions of the needle. . 5. A control device for a sewing machine according to claim 1, characterized in that a belt or a gear is used as a rotating means for connecting a rotating main shaft and an electric motor. 6. A control device for a sewing machine according to claim 4, characterized in that the sewing machine needle is configured to move back and forth once when the rotating main shaft of the sewing machine main body rotates once. 7. A control device for a sewing machine according to claim 1 or 4, characterized in that reverse braking is performed as braking of the electric motor during stop operation. 8. A control device for a sewing machine according to claim 1 or 4, characterized in that a synchronous motor is used as the motor. 9. A control device for a sewing machine according to claim 8, wherein the electric motor is rotated by an inverter. 10. A control device for a sewing machine according to claim 8 or 9, characterized in that dynamic braking is used as braking for the electric motor. 11. In any one of claims 1, 4, 8, and 9, reversal braking is performed after dynamic braking as braking of the electric motor during stop operation. A sewing machine control device featuring: 12. A sewing machine according to any one of claims 1, 4, 8, and 9, characterized in that the instruction signal generating means is actuated by a foot pedal. Control device. 13. A control device for a sewing machine according to claim 12, characterized in that a foot pedal is used which can be stepped forward and backward through a neutral point. 14. A control device for a sewing machine according to any one of claims 1, 4, 8, and 9, characterized in that the electric motor rotates in one direction. 15. In the product described in claim 14, the instruction signal generating means is operated by a foot pedal, and the instruction signal causes the electric motor to rotate by depressing the foot pedal in a forward direction from a neutral point. is outputted from the instruction signal generation means, and when the pedal is returned from the front-depression state to the neutral point, an instruction signal for stopping the rotation of the electric motor is outputted from the instruction signal generation means. Sewing machine control device. 16. In the product described in claim 15, the instruction signal of the instruction signal generating means is configured to be outputted so that the rotational speed of the electric motor increases by increasing the amount of depression in the forward direction. A sewing machine control device featuring: 17. In the item described in claim 15 or 16, an instruction signal for stopping the rotation of the electric motor so that the sewing machine needle comes to a lower position and stops when the pedal is returned from the front-depression state to the neutral point. 1. A control device for a sewing machine, characterized in that the control device is configured such that the instruction signal is output from an instruction signal generating means. 18. In the item set forth in claim 17, when the sewing machine needle is stopped at the lower position, by depressing the pedal in the opposite direction, the electric motor is instructed to rotate so as to move the sewing machine needle to the upper position. 1. A control device for a sewing machine, characterized in that an instruction signal for performing the above is output from an instruction signal generating means. 19. In the product described in claim 16, the instruction signal is generated to instruct the electric motor to operate so as to stop the sewing machine needle at the upper position by depressing the pedal in the forward-depressed state in the opposite direction. 1. A control device for a sewing machine, characterized in that the control device is configured to output from a means.