JP2509106B2 - Electrode moving speed control method of resistance welding machine driven by electric motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the moving speed of electrodes of a resistance welding machine driven by an electric motor.

[0002]

2. Description of the Related Art Conventionally, an electrode of a resistance welding machine driven by a DC or AC electric motor is moved from its open position to a pressurizing point at a constant speed, and is pressed at a low speed from the pressurizing point. It was

[0003]

By the way, in order to perform the welding work promptly, it is advisable to promptly move the electrode from its open position to the pressing point. However, its control is very difficult, and usually this is done by using multiple sensors, but if this is incorrect, the moving speed of the electrode is high,
There is a problem that the electrode is severely worn and deformed by the impact at the time of pressurization.

The present invention has been made in view of the above problems of the prior art. The object of the present invention is to brake the electric motor in the vicinity of the pressurizing point to control the moving speed of the electrode. It is an object of the present invention to provide a method for controlling the electrode moving speed of a resistance welding machine by driving an electric motor, which prevents the electrode from being worn and deformed by dropping the electrode.

Further, another object of the present invention is to provide an electrode moving speed control method for a resistance welding machine driven by an electric motor, which makes it possible to easily control the applied pressure by controlling the electric current of the electric motor in the vicinity of the pressurizing point.

[0006]

In order to achieve the above object, in the method of controlling the electrode moving speed of a resistance welding machine driven by an electric motor according to the present invention, a pulse oscillator interlocked with the rotation of the electric motor is arranged in a control circuit. , Pressure point from the open position of the electrode
The number of pulses commensurate with the movement of the electrode to the neighborhood is controlled in advance.
To increase the moving speed of the electrode during this period.
Process and controller when the expected number of pulses is measured
The process of braking the electric motor by
The rotation speed of the motor, that is, the moving speed of the electrode
Position is detected by the number of pulses and the pulse interval .
Process and the position where the speed becomes low will be the closest to the pressure point
Learning process to correct the planned number of pulses.
It is those that.

Further, the present invention is characterized in that the electric motor is controlled to a constant current in the vicinity of the pressurizing point where the electrode moving speed is reduced.

[0008]

[0009]

An embodiment of the present invention will be described with reference to FIGS. In the figure, reference numeral 1 is an electric motor installed at the rear end of a cylinder 2, and a rotary shaft 3 of the electric motor is provided with a screw. Further, a rod 6 having an electrode 4 attached to the tip and a nut 5 fixed to the screw of the rotary shaft 3 fixed to the rear end is arranged in the cylinder 2 so as to be unable to rotate and move forward and backward. A fixed arm 7 has an electrode 8 attached to one end and the other end fixed to the cylinder 2.

The electric motor 1 is provided with a pulse oscillator 9 which is interlocked with the rotation of the electric motor.
The controller 10 operates according to the signal from to control the electric motor 1.

The resistance welding machine described above is used for the work 11
The motor 1 is driven with the electrode 8 in contact with the rotary shaft 3
When the rod is rotated, the rod 6 is moved forward by the nut 5, the electrode 4 is brought into contact with the work 11, the work 11 is pressurized, and then the welding work is performed.

By the way, the number of pulse transmissions interlocked with the rotation of the electric motor 1 is proportional to the moving amount of the electrode 4. Further, the pulse transmission interval is inversely proportional to the moving speed of the electrode 4, and the pulse transmission interval at the pressurizing position is extremely large, and this limit value can be easily known by learning.

The electrode 4 in the open state advances toward the work 11 when the electric motor 1 is driven and the rotating shaft 3 is rotated, but the electrode 4 is roughly moved to the point A near the pressurizing point. The number of pulses is input to the controller 10 in advance. Therefore, as the electric motor 1 is driven, pulses are sent from the pulse generator 9 to the controller 10, and the electrode 4 moves forward at a high speed V1 (close to the maximum speed of the electric motor 1) until the number reaches the predetermined number of pulses.

When the predetermined number of pulses is sent to the controller 10, the controller 10 brakes the electric motor 1 to drop the electrode 4 to the low speed V2 (about 1/3 of the high speed). The position B where the rotation speed of the electric motor, that is, the moving speed of the electrodes becomes a predetermined low speed V2 due to this braking can be known from the number of pulses and the pulse interval from the time of braking.

If the position of the electrode 4 having the low speed V2 is the point B which is the closest to the pressurizing position, it is not necessary to correct the planned number of pulses, but if it is the point C, it is considerably higher than the pressurizing position. If it is before, it means that the planned pulse number is insufficient, so the correction is made to increase the planned pulse number. Further, when the electrode 4 is in the pressurization position at the velocity V3 before the velocity V2, the scheduled pulse number is too large, so the correction is performed so as to reduce the scheduled pulse number.

In addition to the above control, the electrode 4 has a low speed V
When the value reaches 2, the electric current of the electric motor 1 is maintained at the set current value by controlling the electric current of the electric motor 1 at a constant current, and the pressurizing force corresponding to the set current value is obtained.

[0017]

According to the present invention, a pulse oscillator that interlocks with the rotation of the electric motor is arranged in the control circuit, and the pulse generator is applied from the open position of the electrode.
The number of pulses commensurate with the movement of the electrode near the pressure point is controlled in advance.
Input to the controller and increase the moving speed of the electrode during this
And the control when the planned number of pulses is measured.
The process of braking the electric motor with the controller and this braking
Therefore, the rotation speed of the motor
The speeded position is detected by the number of pulses and the pulse interval.
The process of knowing and the position where the speed becomes slow are close to the pressurizing point.
To correct the planned number of pulses by learning
Since it is composed of two types, it accelerates the movement of the electrode to the vicinity of the pressure point and slows the movement of the electrode in the vicinity of the pressure point to soften the impact from the electrode at the time of pressurization and prevent wear and deformation of the electrode. It is possible to improve the welding work efficiency while being able to
By applying the oscillator to the control circuit,
The system is simpler because no sensor is needed.
Accidents such as breakdowns are reduced, and the electrode open position
The number of pulses commensurate with the movement of the electrode from the
Only input to the controller in advance, after that it will be electrically driven by learning
Since the position to brake the machine is automatically adjusted,
Trouble without a pre-entered values are exceptionally accurate to serial controller
There is no control method .

Further, since the electric current of the electric motor is controlled at a constant current in the vicinity of the pressurizing point where the electrode moving speed is reduced, the electric current of the electric motor is maintained at the set current value, and the work current is adjusted by adjusting the set current value. It is possible to easily control the applied pressure adapted to.

[0019]

[Brief description of drawings]

FIG. 1 is a sectional view of a resistance welding machine driven by an electric motor to which an electrode moving speed control method according to the present invention is applied.

FIG. 2 is an explanatory diagram of an electrode moving speed control method according to the present invention.

[Explanation of symbols]

 1 Motor 4 Electrode 9 Pulse Transmitter 10 Controller

Claims (2)

(57) [Claims] 1. In a resistance welding machine driven by an electric motor, a pulse oscillator interlocked with the rotation of the electric motor is arranged in a control circuit, and an electric current from an electrode open position to a vicinity of a pressurizing point is supplied.
Enter the number of pulses commensurate with the movement of the poles in advance in the controller.
The step of increasing the moving speed of the electrode during this,
When the expected number of pulses is measured, it is driven by the controller.
The process of braking the machine and the rotation of the electric motor by this braking.
A step of detecting the position where the rolling speed, that is, the moving speed of the electrode becomes a predetermined low speed, by the number of pulses and the pulse interval ;
Learn so that the position where the speed becomes low is the closest to the pressure point
A method of controlling an electrode moving speed of a resistance welding machine driven by an electric motor, the method comprising the step of correcting the planned number of pulses . 2. The method of controlling an electrode moving speed of a resistance welding machine driven by an electric motor according to claim 1, wherein the electric motor is controlled at a constant current in the vicinity of the pressurizing point where the electrode moving speed is reduced.