JPH0819873A - Resistance welding equipment and method therefor - Google Patents

Abstract

PURPOSE:To compensate the non-linear loss, to improve the quality of weld and to shorten a welding working time by regulating an air chamber for controlling servo valves for exhausting and supplying using a disturbance observer. CONSTITUTION:The disturbance loss velocity obtd. by converting the disturbance loss found by multiplying the disturbance loss by the disturbance compensating gain is subtracted from the piston friction loss velocity to obtain the pressure difference command value. Accordingly, when an electrode tip 2 is moved, the signal from an arithmetic processing part is transmitted through D/A converting part to a 1st discharge servo valve 35, a 1st supply servo valve 36, a 2nd discharge servo valve 38 and a 2nd supply servo valve 39 so as to prepare this pressure difference commanding value. Then, the air pressure of a 1st air room 27 and a 2nd air room 28 is regulated, so that the electrode tip 2 can be moved effectively at an optimum velocity and the time attending the movement of the electrode tip 2 can be shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding apparatus and a resistance welding method for pressurizing and welding a welding gun with air pressure. Particularly, by compensating for a non-linear disturbance, the pressure of the welding gun is accurately controlled. By doing so, the present invention relates to a resistance welding apparatus and a resistance welding method that can perform welding promptly and improve the quality of welding.

[0002]

2. Description of the Related Art Conventionally, a resistance welding apparatus has been widely used for assembling an automobile body because of its high welding speed and almost no generation of gas. This resistance welding apparatus is provided with a welding gun 5 for resistance welding to the arm 1 of the robot as shown in FIG. 18, and is provided at the tip of the ball screw 4 and the welding gun 5 which move vertically due to rotation. The electrode tip 2 presses the work piece 3 according to a necessary pressure determined in advance according to the material of the work piece 3 and the like, and welds a current necessary for welding due to the contact resistance of the welding surface of the work piece 3. Supply things.

A servomotor 7 for rotating and driving the ball screw 4 is accurately controlled by a servo controller 11 according to a command from a host controller 12 for controlling a robot equipped with welding and a welding gun. . The servo controller 11 is the servo motor 7
A rotation signal from the encoder is detected by a rotation detector 9 such as an encoder, a resolver, and a pulse generator, the rotation signal is added by a counter unit 13, and a speed feedback and a rotor of the servomotor 7 are calculated by an arithmetic processing unit 15 based on the rotation signal. Position feedback is generated and compared with the reference command value in the servo controller 11. If there is a difference between the feedback value and the reference command value, for example, for controlling the current input to the servo motor 7 according to the switching pattern of the PWM control stored in the storage unit 16 so as to eliminate the difference. A gate signal is transmitted to the main circuit unit 17 to a switching element (not shown) in the main circuit unit 17, and the current and frequency compensated by the difference from the reference command value are input to the servo motor 7. The transmission and reception of data such as commands with the host controller is performed via the interface unit 18 for communicating with the outside in the servo controller 11.

The servo controller 11 controls the ball screw 4 by speed control, position control and torque control. In the speed control, a voltage or current having a frequency according to the rotation speed is applied to the servo motor 7 so that the rotation speed of the rotor becomes a desired rotation speed. Then, the position control is performed by rotating the rotor so that the rotation angle of the rotor becomes a desired rotation angle and stopping the rotor when the target rotation angle is reached, for example, by applying a voltage or current of frequency 0 to the servo motor 7. Apply. In the torque control, only the torque applied to the servo motor 7 is controlled, and a voltage or current that gives a desired torque is applied to the servo motor 7.

These speed control, position control, and torque control are proportional-integral control (hereinafter referred to as PI control) or proportional-integral-derivative control (hereinafter referred to as PID control), which have been conventionally used in linear control systems. It is controlled by a method such as. In the PI control, if speed control is taken as an example, when a rotation signal, which is the feedback value of the servo motor 7 detected by the rotation detector 9, is input to the arithmetic processing unit 15 via the counter 13, this feedback control is performed. The value and the reference command value in the arithmetic processing unit 15 are compared, the difference between the reference command value and the reference command value is integrated by a proportional gain, and the gain adjustment is performed so that the response in control is maximized within a range that does not overshoot. The difference from the previous reference command value was added to this value to eliminate the control offset between the feedback value and the reference command value. In addition, in the PID control, since the difference from the previous reference command value is added in performing the integral control, the processing time is delayed by one cycle and the responsiveness of the control system deteriorates. The value obtained by integrating the differential gain with the previously integrated value was output for the time set by the differential gain.

However, in such a resistance welding apparatus using an electric servo, the servo motor attached to the arm of the robot has to be larger in size as the resistance welding apparatus having a larger output, and the resistance welding apparatus supplies the electrode tip. There was also a welding gun with a built-in transformer for boosting the voltage, and the weight of the welding gun was increasing. Therefore, in the resistance welding device using the electric servo, the weight of the welding gun increases and the inertia of the robot arm increases, so that the robot arm must be moved at a low speed in order to accurately move it to a predetermined position during welding. The reason was that the welding work speed slowed down. Further, it requires a robot having a large portable weight, which is uneconomical.

The increase in the weight of the welding gun, which is such a problem, is caused by opening and closing the electrode tip by air pressure as in the automatic welding apparatus of Japanese Patent Application Laid-Open No. 1-107978, thereby making the servomotor unnecessary and welding. The weight of the gun can be reduced.

This automatic welding apparatus mainly comprises a piston and a cylinder for moving a gun arm provided with an electrode tip, a servo valve for adjusting air pressure in the cylinder and opening / closing with an electric signal, and a position of the gun arm. It comprises a robot controller for controlling, a gun controller for welding according to a discrimination signal of a hitting point position from the robot controller, a CPU for processing signals from an opening sensor and the like for controlling servo valves and the like. Then, in the automatic welding apparatus, when a signal for discriminating a hitting point position from the robot controller is input to the gun controller, and further welding condition data stored in advance in the CPU is input from the gun controller, feedback from an opening sensor or the like is given. The control is performed so that the value and the reference command value are equal.

However, in the automatic welding apparatus using such a pneumatic servo, the difference between the feedback value from the opening sensor and the reference command value stored in the memory is simply compared to obtain the reference command value. The linear loss portion is only compensated by compensating for the difference with or by the above-mentioned PI control or the like, and in particular, the non-linearity that occurs when the electrode tip is pressed or released to the workpiece by pneumatic pressure is used. Due to air compression loss in the cylinder which is a loss, loss due to friction of the cylinder, fluctuation of air pressure, etc., it is not possible to optimally adjust the pressure of the air in the cylinder, which may cause holes in the work to be welded and deteriorate the welding quality. The welding time is shortened because hunting occurs when the electrode tip moves due to the aforementioned non-linear loss and the workpiece cannot be pressed quickly. Theft could not be.

[0010]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to improve the quality of welding by compensating for the above-mentioned non-linear loss so that the electrode tip can pressurize or release the object to be welded optimally quickly. It is an object of the present invention to provide a resistance welding device and a resistance welding method capable of improving the workability and shortening the working time for welding.

[0011]

According to the present invention for achieving the above object, a space in a cylinder is divided into a first air chamber and a second air chamber by a piston, and the piston and the cylinder are passed through the piston. The rod-shaped shaft fixed to the piston so as to move with the movement of the piston and an electrode tip for resistance welding by pressurizing an object to be welded at the end of the shaft. A first air circulation port and a second air circulation port are provided on both side surfaces of the cylinder for circulating air to the chamber and the second air chamber, and the first air circulation port and the second air circulation port are connected to each other by an air pipe, and First air for discharging the air in the first air chamber so that the electrode tip separates from the object to be welded
Air discharge means, first air supply means connected to the first air discharge means by an air pipe, and supplying air to the first air chamber so that the electrode tip pressurizes the object to be welded;
The first air circulation port is connected to an air pipe,
A first air supply / exhaust means for supplying / exhausting air to / from the air chamber is connected to the second air circulation port by an air pipe, and the air in the second air chamber is external so that the electrode tip pressurizes an object to be welded. Second air discharging means for discharging to the second air supplying means, and second air supplying means connected to the second air discharging means by an air pipe and supplying air to the second air chamber so that the electrode tip is separated from the object to be welded. A second air supply / exhaust means that is connected to the second air circulation port by an air pipe and supplies or discharges air to or from the second air chamber.

A space in the cylinder is divided into a first air chamber and a second air chamber by the piston, and the rod-shaped shaft is fixed to the piston so as to penetrate the piston and the cylinder and move with the movement of the piston. And a resistance welding apparatus in which an electrode tip for pressurizing an object to be welded and resistance welding is provided at an end portion of the shaft, in the cylinder of the cylinder for circulating air in the first air chamber and the second air chamber. A first air circulation port and a second air circulation port are provided on both side surfaces, respectively, and the first air circulation port is connected to the first air circulation port by an air pipe through which air flows, and the first air chamber detects the pressure of the air in the first air chamber. A first air pressure detecting means, which is connected to the first air pressure detecting means by an air pipe, and which discharges the air in the first air chamber to the outside so that the electrode tip separates from the workpiece. An air discharge means, a first air supply means connected to the first air discharge means by an air pipe, and supplying air to the first air chamber so that the electrode tip pressurizes an object to be welded; A first air supply / exhaust means that is connected to an air circulation port by an air pipe and supplies or discharges air to / from the first air chamber, and is connected to the second air circulation port by an air pipe through which air circulates. Second air pressure detecting means for detecting the pressure of the air in the air chamber, and the second air pressure detecting means are connected to the second air pressure detecting means by an air pipe, and the air in the second air chamber is exposed to the outside so that the electrode tip pressurizes the workpiece. Second air discharging means for discharging, second air supplying means connected to the second air discharging means by an air pipe, and supplying air to the second air chamber so that the electrode tip is separated from the workpiece. Second air discharge means and empty Is connected by a pipe, a second air supply and discharge means for supplying or discharging air to the second air chamber, said first air supply means, the first air supply outlet means, said second air supplying means and the second
A third air pressure which is connected to the air supply / discharge means by an air pipe and detects an air pressure supplied to the first air supply means, the first air supply / discharge means, the second air supply means and the second air supply / discharge means. Detecting means, piston position detecting means for detecting the position of the piston, the first air pressure detecting means, the second air pressure detecting means, the third air pressure detecting means, and the piston position detecting means. Piston position control means for varying the air pressure of the first air chamber and the second air chamber by a signal to move the piston to a desired position.

A space in the cylinder is divided into a first air chamber and a second air chamber by the piston, and a rod-shaped shaft fixed to the piston so as to penetrate the piston and the cylinder and move with the movement of the piston. An electrode tip that pressurizes and welds an object to be welded provided at the end of the shaft, and the air pressure of the first air chamber,
The air pressure of the second air chamber and the position of the piston are detected, the air pressures of the first air chamber and the second air chamber are varied, and the piston is moved to a desired position so as to be optimally welded by the electrode tip. In a resistance welding device comprising piston position control means, a loss generated during movement of the piston is separated into a linear loss and a non-linear loss, the separated non-linear loss generating circuit is modeled, and the modeled non-linear loss is modeled. The non-linear loss is calculated from the loss generating circuit, and the calculated non-linear loss is compensated to move the piston to a desired position.

A space in the cylinder is divided into a first air chamber and a second air chamber by the piston, and the rod-shaped shaft is fixed to the piston so as to penetrate the piston and the cylinder and move with the movement of the piston. An electrode tip that pressurizes and welds an object to be welded provided at the end of the shaft, and the air pressure of the first air chamber,
Piston position for moving the piston to a desired position so that the air pressures of the first air chamber and the second air chamber are varied depending on the air pressure of the second air chamber and the position of the piston so that welding can be performed optimally by the electrode tip. In a resistance welding device comprising control means, a loss generated when the piston moves is separated into a linear loss and a non-linear loss, the separated non-linear loss generation circuit is modeled, and the modeled generation circuit is used. It is characterized in that a nonlinear loss is calculated and the calculated nonlinear loss is compensated to move the piston at a desired speed.

A space in the cylinder is divided into a first air chamber and a second air chamber by the piston, and the rod-shaped shaft is fixed to the piston so as to penetrate the piston and the cylinder and move with the movement of the piston. An electrode tip that pressurizes and welds an object to be welded provided at the end of the shaft, and the air pressure of the first air chamber,
The air pressure of the second air chamber and the position of the piston are detected, the air pressures of the first air chamber and the second air chamber are varied, and the piston is moved to a desired position so as to be optimally welded by the electrode tip. In a resistance welding device comprising piston position control means, a loss generated during movement of the piston is separated into a linear loss and a non-linear loss, and the separated non-linear loss generation circuit is modeled, and the modeled generation is performed. It is characterized in that a non-linear loss is calculated from the circuit, the calculated non-linear loss is compensated, and the object to be welded is pressurized with a desired pressing force by the electrode tip.

At the time of maximum pressurization of the piston, the first pressure
The first air supply / discharge means is fully opened to supply air to the air chamber, and the second air supply / discharge means is fully opened to discharge air from the second air chamber to the outside. Is characterized by.

When the piston is fully opened, the first
The first air supply / discharge means is fully opened for discharging air from the air chamber to the outside, and the second air supply / discharge means is fully opened for supplying air to the second air chamber. Is characterized by.

[0018]

The resistance welding apparatus and the resistance welding method of the present invention configured as described above operate as follows.

In this apparatus, air is circulated from the first air circulation port and the second air circulation port to the first air chamber and the second air chamber, respectively, and when welding is performed by pressurizing the object to be welded with the electrode tip. , A first air discharge means connected to the first air circulation port reduces the air pressure of the first air chamber and a first air supply means increases the air pressure of the first air chamber, and is connected to the second air circulation port. By closing the second air discharge means and the second air supply means or by reducing the air pressure of the second air chamber by the second air discharge means and closing the second air supply means, the first air chamber and the second air chamber are closed. The pressure difference of the air pressure is adjusted so as to be the target value that can obtain the required pressing force.
Further, when the electrode tip is released from the object to be welded, the second air exhausting means connected to the second air circulation port is used for the second
The air pressure in the air chamber is reduced and the air pressure in the second air chamber is increased by the second air supply unit, and the first air discharge unit and the first air supply unit connected to the first air circulation port are closed or the first air supply unit is closed. By reducing the air pressure of the first air chamber by the air discharge means and closing the first air supply means, a pressure difference between the air pressures of the first air chamber and the second air chamber is obtained as a desired value for obtaining a force for opening. Adjust so that When the electrode tip is rapidly pressed against the object to be welded, the air pressure in the first air chamber is rapidly increased by the first air supply / discharge means connected to the first air circulation port, and the second air is discharged. The second by the second air supply and discharge means connected to the flow port
The air pressure in the air chamber is rapidly reduced. Further, when the electrode tip is rapidly opened to the object to be welded, the air pressure in the first air chamber is rapidly reduced by the first air supply / discharge means connected to the first air circulation port, and the second air is discharged. The air pressure in the second air chamber is rapidly increased by the second air supply / discharge means connected to the flow port.

In this device, the air pressure in the first air chamber and the air pressure in the second air chamber, which are divided into two by the piston, are set to the first pressure.
The maximum air pressure that can be applied to the first air chamber or the second air chamber is detected by the air pressure detection means and the second air pressure detection means, respectively. And
This device, when pressurizing the workpiece with the electrode tip,
In order for the piston position feedback value detected by the piston position detecting means by the piston position detecting means to be the target value of the position of the piston at which the necessary pressurizing force inside the piston position controlling means is obtained, the first air pressure detecting means detects it. The first air chamber is connected to the first air circulation port so that the air pressure of the first air chamber reaches the target value of the air pressure inside the piston position control means within the range of the maximum air pressure detected by the third air pressure detection means. The air pressure of the second air chamber detected by the second air pressure detecting means is the target of the air pressure inside the piston position controlling means, while the first air discharging means reduces the pressure and the first air supplying means increases the air pressure of the first air chamber. To the value
The second air discharge means and the second air supply means connected to the second air circulation port are closed, or the air pressure of the second air chamber is reduced by the second air discharge means and the second air supply means is closed. When the electrode tip is released from the object to be welded, the piston position feedback means detects the position feedback value of the piston detected by the piston position detection means, and the force necessary for opening the inside of the piston position control means is obtained. In order to reach the target value of the piston position, the air pressure in the first air chamber detected by the first air pressure detecting means is within the range of the maximum air pressure detected by the third air pressure detecting means, and the air pressure inside the piston position control means is increased. To reach the target value of
The second air discharge means connected to the air circulation port reduces the air pressure of the second air chamber and the second air supply means increases the air pressure of the second air chamber, and the first air pressure detection means detects the first air pressure. The first air discharge means and the first air supply means connected to the first air circulation port are closed or the first air discharge means is set so that the air pressure in the air chamber becomes the target value of the air pressure inside the piston position control means. Thus, the air pressure in the first air chamber is reduced and the first air supply means is closed. When the electrode tip is rapidly pressed against the object to be welded, the air pressure in the first air chamber is increased by the first air supply / discharge means connected to the first air circulation port controlled by the piston position control means. The pressure is rapidly increased, and the air pressure in the second air chamber is rapidly reduced by the second air supply / discharge means connected to the second air circulation port. Further, when the electrode tip is rapidly opened to the object to be welded, the air pressure in the first air chamber is increased by the first air supply / discharge means connected to the first air circulation port controlled by the piston position control means. The pressure is rapidly reduced, and the second air is supplied by the second air supply / discharge means connected to the second air circulation port.
The air pressure in the air chamber is rapidly increased.

The present method separates the loss generated during the movement of the piston into a linear loss and a non-linear loss, and models the separated non-linear loss generation circuit to model the non-linear loss generation path and the non-linear loss. It is possible to quantitatively detect the loss value of, calculate the nonlinear loss from this modeled nonlinear loss generation circuit, compensate this calculated nonlinear loss, and adjust the air pressure applied to the piston It is possible to move the piston provided with the electrode tip to the desired position. Therefore, the present method can accurately and promptly move the position of the piston so that the force required for the electrode tip to pressurize the work piece or the electrode tip to release the work piece from the work piece is obtained.

The present method separates the loss generated during the movement of the piston into a linear loss and a non-linear loss, and models the separated non-linear loss generation circuit to determine the non-linear loss generation path and the non-linear loss. It is possible to quantitatively detect the loss value of, calculate the nonlinear loss from this modeled nonlinear loss generation circuit, compensate this calculated nonlinear loss, and adjust the air pressure applied to the piston The piston provided with the electrode tip can be moved at a desired speed. Therefore, the present method is to move the electrode tip to the work piece to be welded or to move the electrode tip from the work piece to be welded by precisely moving the piston at a desired speed. It is possible to more precisely obtain the force required to release the object to be welded by the pressing force or the electrode tip.

The present method separates the loss that occurs during the movement of the piston into a linear loss and a nonlinear loss, and models the separated nonlinear loss generation circuit to model the nonlinear loss generation path and the nonlinear loss. It is possible to quantitatively detect the loss value of, calculate the nonlinear loss from this modeled nonlinear loss generation circuit, compensate for this calculated nonlinear loss, and adjust the air pressure applied to the piston. Thus, the object to be welded can be pressed with a desired pressing force. Therefore, this method can improve the quality of welding without causing holes in the workpiece by freely changing the pressure applied to the workpiece when the workpiece is pressed by the electrode tip. .

According to the present method, when the electrode tip is pressed against the object to be welded, the first air supply / discharge means connected to the first air circulation port controlled by the piston position control means is used for the first air chamber. Is rapidly increased, and the air pressure in the second air chamber is rapidly reduced by the second air supply / discharge means connected to the second air circulation port. Therefore, according to the present method, the work to be welded can be quickly pressed by the electrode tip, so that the welding work time can be shortened.

According to the present method, when the electrode tip is opened to the object to be welded, the first air supply / discharge means connected to the first air circulation port controlled by the piston position control means is used. The air pressure of the second air chamber is rapidly reduced, and the air pressure of the second air chamber is rapidly increased by the second air supply / discharge means connected to the second air circulation port. Therefore, according to the present method, the work to be welded can be quickly released by the electrode tip, so that the welding work time can be shortened.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A resistance welding apparatus and a resistance welding method according to the present invention will be described below with reference to the accompanying drawings.

The resistance welding apparatus of the present invention includes a pneumatic circuit portion 21 for adjusting the air pressure by a servo valve or the like in order to pressurize or release the electrode tip 2 to the object to be welded, and a servo valve in the pneumatic circuit portion 21. There is an electric circuit unit 61 that performs opening and closing according to the calculated control amount.

In the pneumatic circuit section 21, the space in the cylinder 25 is divided into a first air chamber 27 and a second air chamber 28 by a piston 23 as shown in FIG. 1, and the piston 23 and the cylinder 25 are penetrated to move the piston 23. A rod-shaped shaft 29 fixed to the piston 23 so as to move with
And an electrode tip 2 for pressurizing and welding resistance to the object to be welded on the end of the shaft 29, and a rack 51 is formed on the other side of the shaft 29 to rotate the pinion 52 with the movement of the piston 23 to move the position of the piston. A piston position sensor 53 which is a piston position detecting means for detecting
A first air circulation port 31 and a second air circulation port 32, which are respectively provided on the side surfaces at both ends of the cylinder 25 for circulating air in the air chamber 27 and the second air chamber 28, a first air circulation port 31, and an air tube. A first discharge servo valve 35, which is a first air discharge means that is connected by 33 and discharges the air in the first air chamber 27 to the outside so that the electrode tip 2 is separated from the workpiece 3. The servo valve 35 is connected to the air pipe 33, and the electrode tip 2 is welded to the object 3 to be welded.
For supplying air to the first air chamber 27 so as to pressurize the first
A first supply servo valve 36 which is an air supply means, a first discharge servo valve 35 and an air pipe 33 which are connected to each other and which are first supply and discharge means for supplying or discharging air to the first air chamber 27. A second air discharge means that is connected to the electromagnetic valve 37, the second air circulation port 32, and the air pipe 33 and discharges the air in the second air chamber 28 to the outside so that the electrode tip 2 pressurizes the workpiece 3. A second discharge servo valve 38 and a second discharge servo valve 38 are connected to the second discharge servo valve 38 by an air pipe 33 to supply air to the second air chamber 28 so that the electrode tip 2 separates from the workpiece 3. The second supply servo valve 39, which is an air supply means, the second discharge servo valve 38 and the air pipe 33 are connected to each other.
A second electromagnetic valve 41, which is a second air supply / discharge means for supplying or discharging air to the air chamber 28, and a first air pressure detecting means, which is a first air pressure detecting means for detecting the air pressure of the first air chamber 27.
The pressure sensor 43 and a second pressure sensor 44 which is a second air pressure detecting means for detecting the air pressure of the second air chamber 28.
A third pressure sensor 45 for detecting the original pressure of the air supplied to the first supply servo valve 36 and the second supply servo valve 39, a compressor 47 for compressing the air, and this compressor. There are a motor 48 for driving the motor 47, a filter 49 for filtering dust and the like from entering the air circuit portion 21, and a regulator 46 for keeping the air pressure from the compressor 47 constant.

The piston position sensor 53 for detecting the position of the piston does not necessarily have to be detected by mechanical drive composed of a rack and a pinion. For example, a reflecting plate or the like may be provided on the shaft to reflect the laser beam. Since the position of the piston can be detected in a non-contact manner by detecting the light, the mechanical loss for detecting the position can be reduced.

The electric circuit section 61 converts the signals detected by the piston position sensor 53, the second pressure sensor 43, the second pressure sensor 44 and the third pressure sensor 45 as shown in FIG. 2 into digital signals. A / D converter 62
And the first air chamber 27 and the second air chamber 28 according to the digital signal converted by the A / D converter 62.
Of the piston position control means for controlling the piston 23 to a desired position so that the air pressure of the piston 23 can be optimally welded by the electrode tip 2, and the inertia of the piston for controlling the air pressure. Storage unit 65 in which parameters are stored, and host controller 1
2, an interface section 67 for transmitting a signal for data communication with the first electromagnetic valve 37 or the like for transmitting the electromagnetic valve to the first electromagnetic valve 37, and an analog digital signal from the arithmetic processing section 63 for opening and closing the first discharge serve valve 35 and the like. There is a D / A converter 69 for converting into a signal.

This device operates as follows.

The control performed by the arithmetic processing unit 63 of this apparatus is a positioning mode for controlling the position of the electrode tip 2 provided at the tip of the shaft 29, and the electrode tip 2 pressurizes and releases the workpiece 3 to be welded. Speed control mode for controlling the speed of the electrode tip 2 when the electrode tip 2 is to be welded 3
Pressure control mode for controlling the pressure applied when pressurizing, the full open pressurization open mode when maximizing pressurization or opening, and the first air chamber 27 and the second air chamber 27 which are the result of these processes.
There is a pressure difference command distribution control for processing a pressure difference command value which is a pressure difference in the air chamber 28 and distributing a signal to each servo valve so that the signal becomes the pressure difference command value.

FIG. 3 is a flow chart of the control performed by the arithmetic processing unit 63. The operation mode signal from the host controller 12 is the interface unit 67 in the electric circuit unit 61.
By being input to the arithmetic processing unit 63 via (S1)
In the positioning mode (S2), the positioning mode subroutine process is performed (S3), in the speed control mode (S4), the speed control mode subroutine process is performed (S5), and the pressing force control mode is used. (S6),
The subroutine processing of the pressure control mode is performed (S7),
In the case of the full open pressure release mode (S8), the full open pressure release mode subroutine process is performed (S9), and finally the pressure difference command distribution control subroutine process is performed (S10).

Further, a disturbance observer is used in these positioning mode, speed control mode and pressure control mode in order to compensate for fluctuations in the parameters calculated for control in the arithmetic processing unit 63 due to non-linear loss. . For example, when the apparatus optimally performs welding in an ideal state, the parameters processed by the arithmetic processing unit 63 from the movement of the robot arm to the pressurization of the object to be welded to the welding are optimal values. Exists as a value. Then, the disturbance observer normally assumes that, when the resistance welding device welds, there is always a nominal value, and compares the actual parameter and the nominal value when the resistance welding device moves, with this nominal value. The difference is estimated as the disturbance. Further, in order to estimate the fluctuation of the parameters using the disturbance observer, it is necessary to set the intrusion route of the disturbance.

In the present apparatus and method, if the operating environment temperature is in the range of about 15 to 35 ° C., the change in the viscosity of the air due to the temperature change does not cause a large non-linear disturbance loss, so that it does not cause a problem, so it is non-linear. Not treated as a disturbance.

Hereinafter, when the disturbance invasion path is set and the disturbance observer is obtained,

[0037]

[Equation 1]

The relationship of the internal pressure of the cylinder at this time is as follows.

[0039]

[Equation 2]

The flow rate Gi of the air passing through the servo valve is given by: Si is the effective opening area of the servo valve, Pu is the upstream pressure of the servo valve, and Pd is the downstream pressure of the servo valve.

[0041]

(Equation 3)

[0042]

[Equation 4]

It becomes Linearize this system.

ΔP = P1−P2, ΔS = S1−S2 Equation (2) Equation- (3) Equation (5) is applied to the result:

[0045]

(Equation 5)

It becomes However, Ps is the source pressure of the supply side servo valve, and Po is the atmospheric pressure after exhaust.

From this, the state equation of the resistance welding apparatus of the present embodiment is calculated from the equations (1) and (6) as follows:

[0048]

(Equation 6)

[0049]

(Equation 7)

This equation is input to a control design support tool such as MATRIXx (Matrix X: US ISI import agent Sumisho Electronics Co., Ltd.) to form a stable system that compensates for air compressibility. Such a state feedback coefficient is obtained by a method such as LQG or H ^∞ control method or pole placement method. Alternatively, the state feedback coefficient can be calculated manually. Next, the disturbance observer that estimates the disturbance is obtained.

The expansion system including the disturbance is

[0052]

(Equation 8)

[0053]

[Equation 9]

[0054]

[Equation 10]

It becomes Using this, the disturbance observer is as follows.

[0056]

[Equation 11]

Where gd: observer gain

[0058]

(Equation 12)

The disturbance observer 81 obtained as described above
Is the piston position sensor 5 as shown in the block diagram of FIG.
The position detection signal after the digital conversion P ^* from 3 obtains the speed of the piston 23 V ^* by differentiating with a differentiator 83a, further differentiator velocity V ^* of the piston 23 83
The acceleration a ^* of the piston 23 is calculated by differentiating with b, and the inertia J of the piston 23 including the shaft 29 is multiplied by this by the multiplier 85a to calculate the piston inertial loss T ^* which is the loss due to inertia. Then, the velocity V ^{* of the} piston 23 is multiplied by the dynamic friction coefficient b by the multiplier 85b to calculate the piston friction loss F ^* which is the loss due to the friction of the piston 23. On the other hand, the air pressure in the first air chamber 27 is detected by the first pressure sensor 43, and the second pressure sensor 4
Subtracted by the air pressure of the second air chamber detected in 4,
It is obtained as a differential pressure HN ^* between the first air chamber 27 and the second air chamber. This differential pressure HN ^* is multiplied by the cylinder area S by the multiplier 85c and becomes the force M ^* applied to the piston 23 by the air pressure. Therefore, the disturbance observer 81
Estimates obtained by subtracting the force M ^* from the piston inertia losses T ^* and piston friction loss F ^* respectively to be non-linear disturbances loss G ^*.

FIG. 5 is a flow chart for explaining the control of the disturbance observer.

The piston velocity V ^* is calculated by differentiating the position feedback of the piston 23 (S1
1), the piston acceleration speed a ^* is calculated by further differentiating the piston speed V ^* (S12), and the shaft 2
9 multiplying seeking piston inertia losses T ^* in ^* inertia J acceleration rate a of the piston 23 including the (S13), multiplied by the dynamic friction coefficient b of the piston 23 on the piston speed V ^* Request piston friction loss F ^* ( S14). And the first
The differential pressure HN ^* between the air chamber 27 and the second air chamber is multiplied by the cylinder area S to obtain the force M ^* applied from the air pressure to the piston (S15). From this force M ^* , the piston inertia loss T
^{* And} piston friction loss F ^* are respectively subtracted to calculate a nonlinear disturbance loss G ^* (S16), and the disturbance loss G ^* is compensated in the position control mode, speed control mode and pressure control mode described above, and the optimum parameter is set. Can be obtained.

The positioning mode 91 using the disturbance observer 81 is a positioning mode signal P which is a signal for performing the positioning mode 91 as shown in the block diagram of FIG.
When s is input to the command position selector 93, the command position selector 93 outputs the command position data from the RAM in the arithmetic processing unit 63 in which the command position data PD ^* of the piston position from the host controller 12 is stored. Load the PD ^*, the command position data PD ^* from subtracting the P ^* is a position feedback value of the actual piston, the position deviation PH ^* a No. with calculated memory unit 95 of the position deviation PH ^* with No. m of The position deviation PH ^* is calculated by multiplying the position deviation PH ^* by the position gain Kp by the multiplier 97a, and the position deviation speed Pa ^* is obtained. Then, the current speed aref ^* is obtained by adding the previous speed command value from the speed command storage unit 98 in which the previous speed command value is stored after the additional command is added by the additional sign adder 94a. The acceleration speed becomes Va. The absolute value comparator 99 compares the absolute values of the acceleration speed Va, the maximum speed Vmax ^{* of the} piston with Vmax added with the additional sign by the additional adder 94b, and the position deviation speed Pa ^* described above, and the absolute values of the respective values are compared. The speed command value Vref ^* has the smallest value among the above. This speed command value Vref ^* has a shape obtained by cutting a triangle as shown in FIG.
In step 8, the deceleration speed Vd is obtained by adding it to the position deviation speed Pa ^* . Also, the speed command value Vref
^* Is the pressure difference gain K converted to the differential pressure HN ^* by the multiplier 96a.
The piston friction loss speed HG ^* , which is obtained by multiplying pr by converting the piston friction loss F ^* into speed, and the piston inertia loss speed VG ^*, which is obtained by multiplying piston speed V ^* by speed gain Kv, and the piston inertia loss T ^* is converted into speed, and the disturbance. The pressure difference command value Hre is obtained by subtracting the loss G ^* by the disturbance compensation gain Kd and converting the disturbance loss G ^* into a velocity, which is the disturbance loss velocity Gr ^*.
f ^* . Therefore, when positioning the electrode tip 2, the present apparatus sends a signal from the arithmetic processing unit 63 via the D / A conversion unit 69 so that the pressure difference command value Href ^* is obtained. It transmits to the 1st supply servo valve 36, the 2nd discharge servo valve 38, and the 2nd supply servo valve 39, adjusts the air pressure of the 1st air chamber 27 and the 2nd air chamber 28, and causes hunting etc. of the electrode tip 2. Since the positioning can be performed without doing so, the time required for the welding work can be shortened.

FIG. 8 is a flow chart for explaining the positioning mode subroutine.

The command position data PD ^* from the host controller 12 stored in the RAM in the arithmetic processing unit 63 is subtracted by the position feedback value P ^* of the piston 23 detected by the piston position sensor 53 to obtain the position deviation PH ^*. Is calculated (S21), and the position gain PH ^* is integrated with the position deviation PH ^* to calculate the position deviation speed Pa ^* (S22). From the current speed aref ^* of the piston 23 to the previous piston 23
Is calculated to calculate the acceleration speed Va of the piston 23 (S23), the absolute values of the position deviation speed Pa ^* , the acceleration speed Va and the maximum speed Vmax are compared, and the minimum value is set as the speed command value Vref ^* . (S24). The position deviation speed Pa ^* is added to this speed command value Vref ^* to determine the deceleration speed V
d is calculated (S25). The pressure difference command value Href ^* is obtained by subtracting the piston friction loss speed HG ^* , the piston inertial loss speed VG ^*, and the disturbance loss speed Gr ^* converted into the speed from the speed command value Vref ^* (S26).

In the speed control mode 101 using the disturbance observer 81, the speed control mode signal Vs which is a signal for performing the speed control mode 101 is input to the command speed selector 102 as shown in the block diagram of FIG. Then, the commanded speed selector 102 causes the piston 2 from the host controller 12 to operate.
3 speed command speed data VD ^* of RAM of the arithmetic processing unit 63 which is stored a command is read velocity data VD ^*, disturbance observer 8 from the command speed data VD ^*
V ^* which is the actual position feedback value of the piston 23 calculated by 1 is subtracted, the speed deviation VH ^* is calculated, and the code memory 103 stores the code m of this speed deviation VH ^* and the speed deviation. VH ^* is converted to an absolute value by the absolute value unit 104 to obtain the absolute value of speed deviation | VH ^* |. The absolute value comparator 105 compares the absolute value of the current speed aref ^* of the piston 23 and the absolute value of the speed deviation | VH ^* |, and the absolute value of each absolute value is the speed command value Vc.
^*, And the speed deviation absolute value | VH ^* | is added to obtain the speed deviation Vp ^* . In addition, the speed command value Vc ^* is added to the speed command value Vc ^* by the index number adder 107 and added to the previous speed command.
06 and the differential pressure H by the multiplier 108a.
Multiply N ^* by the pressure difference gain Kpr to obtain piston friction loss F
^The piston friction loss speed HG ^* and the disturbance loss G ^{* obtained} by converting ^* into the speed are multiplied by the disturbance compensation gain Kd to obtain the disturbance loss G.
^The pressure difference command value Href ^* is obtained by subtracting the disturbance loss speed Gr ^* obtained by converting ^* into speed. Therefore, the device
When moving the electrode tip 2, this pressure difference command value Hre
The signal from the arithmetic processing unit 63 is supplied to the first discharge servo valve 35, the first supply servo valve 36, the second discharge servo valve 38 and the second supply so as to be f ^* via the D / A conversion unit 69. The air pressure of the first air chamber 27 and the second air chamber 28 is adjusted by transmitting it to the servo valve 39 for use, so that the electrode tip 2 can be moved at an optimum speed without waste, and the time required for the movement of the electrode tip 2 can be reduced. Therefore, the time required for welding work can be shortened.

FIG. 10 is a flow chart for explaining the speed control mode subroutine.

The command speed data VD ^* from the host controller 12 stored in the RAM in the arithmetic processing unit 63 is subtracted by the speed feedback value V ^* of the piston 23 calculated by the disturbance observer 81, and further converted into an absolute value. speed deviation absolute value each | VH ^* | a seeking (S31), the speed deviation absolute value | VH ^* | and the current speed compares the absolute value of aref ^*, a speed command value Vc ^* to the minimum value (S32 ). The speed deviation absolute value | VH ^* | is added to this speed command value Vc ^* to calculate the speed deviation Vp ^* (S33). The pressure difference command value Href ^* is obtained by subtracting the previous speed command value, the piston friction loss speed HG ^* and the disturbance loss speed Gr ^* converted into speed from the speed command value Vc ^* (S34).

In the pressing force control mode 111 using the disturbance observer 81, the pressing force control mode signal Bs, which is a signal for performing the pressing force control mode 111 as shown in the block diagram of FIG. 11, is the command pressure selector. is input to 112, read command pressure data BD ^* from the RAM of the arithmetic processing unit 63 to the command pressure selector 112 command pressure data BD ^* the pressure of the piston 23 from the host controller 12 is stored . The comparator 115 compares the command pressure data BD ^* and Bmax and determines whichever has the smallest value as the pressure command value Bc ^* . This pressure command value Bc ^* becomes a graph having positive and negative values for pressurization or opening by the electrode tip 2 as shown in FIG. 7 (b), and the command pressure data BD ^* is added to give a command. Pressure B
ref ^* . This command pressure Bref ^* is calculated by the multiplier 1
In step 17, the disturbance loss G ^* is multiplied by the disturbance compensation gain Kd, and the disturbance loss G ^* is converted into a velocity, which is subtracted by the disturbance loss velocity Gr ^* to obtain a pressure difference command value Href ^* . Therefore,
In the present device, when the electrode tip 2 is pressed, the signal from the arithmetic processing unit 63 is passed through the D / A conversion unit 69 so that the pressure difference command value Href ^* is obtained.
5, the first supply servo valve 36, the second discharge servo valve 38 and the second supply servo valve 39,
Since the air pressures of the first air chamber 27 and the second air chamber 28 are adjusted, the pressure of the electrode tip 2 can be optimized.
It is possible to improve the quality of welding by eliminating the perforation of the workpiece 3 due to welding failure.

FIG. 12 is a flow chart for explaining a subroutine of the pressure control mode.

The command speed data BD ^* from the host controller 12 stored in the RAM in the arithmetic processing unit 63 is compared with the maximum pressure Bmax ^*, and the minimum value is set as the pressure command value Bc ^* (S41). Command pressure data BD ^* is added to command value Bc ^* to calculate command pressure Bref ^* (S4
2). The pressure difference command value Href ^* is obtained by subtracting the disturbance loss speed Gr ^* converted into the speed from the pressure command value Bc ^* (S43).

In the full open pressurization release mode 121, when the full open pressurization signal Vk ^* is input to the full open pressurization release mode setter 123 as shown in the block diagram of FIG. The a-contact drive signal Vk1a of the first electromagnetic valve 37 is input to the first electromagnetic valve 37, and the air pressure adjusted by the regulator 46 is directly applied from the first electromagnetic valve 37 to the first air chamber 27 and to the second electromagnetic valve 41. B contact drive signal V of the second electromagnetic valve 41
By inputting k2b and discharging the air in the second air chamber 28 to the outside through the second electromagnetic valve 41, the electrode tip 2
Is applied to the workpiece 3 at the maximum speed and the maximum pressure.
Further, the full-open pressure release mode 121 uses the full-open release signal Ve.
^{When *} is input to the full open pressurization release mode setting device 123, the arithmetic processing unit 63 passes through the interface unit 67 and
The b-contact drive signal Ve1b of the first electromagnetic valve 37 is input to the electromagnetic valve 37 to discharge the air in the first air chamber 27 to the outside through the first electromagnetic valve 37 and the second electromagnetic valve 41 to the second electromagnetic valve 41. Valve 41 a contact drive signal Ve2a
By directly inputting the air pressure adjusted by the regulator 46 from the second electromagnetic valve 41 to the second air chamber 28, the electrode tip 2 can be released from the workpiece 3 at the maximum speed.

In the full open pressure release mode, all of the first discharge servo valve 35, the first supply servo valve 36, the second discharge servo valve 38 and the second supply servo valve 39 may be closed. However, when pressurizing fully, the first discharge servo valve 35 is closed, and the first supply servo valve 36 is closed.
And the second discharge servo valve 38 are opened, the second supply servo valve 39 is closed, and when fully opened, the first discharge servo valve 35 is closed and the first supply servo valve 36.
And the second discharge servo valve 38 are opened and the second supply servo valve 39 is closed to increase the opening area of the entire valve to reduce ventilation loss and more effective movement speed and pressure of the electrode tip 2. You can do it.

FIG. 14 is a subroutine for explaining the subroutine of the full open pressure release mode.

In the case of full open pressurization (S51), the full open pressurization signal Vk ^{* is set} to the a-contact drive signal Vk of the first electromagnetic valve 37.
1a and b contact drive signal Vk2 of the second electromagnetic valve 41
b to the first electromagnetic valve 37 and the second electromagnetic valve 41, respectively (S52), and the first air chamber 27 is directly pressurized by the air pressure adjusted by the regulator 46 to rapidly release the air in the second air chamber 28 to the outside. Discharge. Then, in the case of full open (S51), the full open signal Ve ^* is set as the first contact drive signal Ve1b of the first electromagnetic valve 37 and the first contact drive signal Ve2a of the second electromagnetic valve 41, respectively.
Send to the electromagnetic valve 37 and the second electromagnetic valve 41 (S
53), the air in the first air chamber 27 is rapidly discharged to the outside, and the air in the second air chamber 28 is directly pressurized by the air pressure adjusted by the regulator 46.

Positioning mode 91, speed control mode 10
1 and the pressure difference command value Href ^* obtained in the pressing force control mode 111 are processed by the pressure difference command distribution unit 131 that performs pressure difference command distribution control as shown in the block diagram of FIG. The valve 36, the first discharge servo valve 35, the second supply servo valve 39, and the second discharge servo valve 38 are driven so that the air pressures of the first air chamber 27 and the second air chamber 28 are the pressure difference command value Href ^*.
The signal becomes Therefore, the pressure difference command value H
The polarity of ref ^* is determined by the polarity comparator 132a, and when the polarity is positive, that is, when the workpiece 3 is pressurized by the electrode tip 2, the pressure difference command value Hr is calculated by the divider 133a.
Source pressure H3 for detecting ef ^* by the third pressure sensor 45
Is divided by to become the first air chamber supply signal Hk1. Further, when the pressure difference command value Href ^* is subtracted from the air pressure feedback value H1 ^* of the first air chamber 27 detected by the first pressure sensor 43 and is positive by the polarity comparator 132b, the air in the first air chamber 27 is reduced. Signal He for discharging the first air chamber for discharging
It becomes 1. Then, the first air chamber supply signal Hk1 and the first air chamber discharge signal He1 are output from the arithmetic processing unit 63 by D / A.
The first supply servo valve 3 via the converter 69, respectively.
6 and the first discharge servo valve 35, and adjusts the air pressure in the first air chamber 27 so that the air pressure difference between the first air chamber 27 and the second air chamber 28 becomes the pressure difference command value Href ^* . On the other hand, the pressure difference command value Hr ^* input to the valve drive command generator 135a for generating a command for optimizing the air pressure in the second air chamber 28 based on the pressure difference command value Href ^* .
ef ^* is a valve shutoff signal H for closing the second supply serve valve 39 by the valve drive command generator 135a.
close 2 and the second valve adjustment signal Hopen2 for adjusting the air pressure of the second air chamber 28 so that the air pressure difference between the first air chamber 27 and the second air chamber 28 becomes the pressure difference command value Href ^* . Then, the valve shutoff signal Hclose 2 signal and the second valve adjustment signal Hopen 2 are supplied to the arithmetic processing unit 6.
3 to the second supply servo valve 39 and the second discharge servo valve 38 via the D / A converter 69, and the air pressure difference between the first air chamber 27 and the second air chamber 28 is the pressure difference command value. The air pressure in the second air chamber 28 is adjusted so as to be Href ^* .

The polarity of the pressure difference command value Href ^* is determined by the polarity comparator 132a, and when the polarity is negative, that is, when the electrode tip 2 is released from the workpiece 3, the pressure difference command value Href ^* is added. No. is inverted by the additional number inverter 137 and then divided by the source pressure H3 detected by the third pressure sensor 45 by the divider 133b, and the second air chamber supply signal H
k2. Further, the pressure difference command value Href ^* is subtracted from the air pressure feedback value H2 ^* of the second air chamber 28 detected by the second pressure sensor 44, and if the polarity comparator 132c is positive, the air pressure of the second air chamber 28 is reduced. Becomes the second air chamber discharge signal He2 for discharging. Then, the second air chamber supply signal Hk2 and the second air chamber discharge signal He2 are respectively output from the arithmetic processing unit 63 via the D / A conversion unit 69 to the second air chamber second signal.
Supply servo valve 39 and second discharge servo valve 38
The air pressure in the second air chamber 28 is adjusted so that the air pressure difference between the first air chamber 27 and the second air chamber 28 becomes the pressure difference command value Href ^* . On the other hand, the pressure difference command value Hre
The pressure difference command value Href ^* input to the valve drive command generator 135b for generating a command for optimizing the air pressure of the first air chamber 27 by f ^* is calculated by the valve drive command generator 135b. The valve cutoff signal Hclose 1 for closing the valve 36 and the air pressure difference between the first air chamber 27 and the second air chamber 28 are the pressure difference command value Href.
It becomes the first valve adjustment signal Hopen1 for adjusting the air pressure of the first air chamber 27 so as to be ^* . Then, the valve shutoff signal Hclose 1 signal and the first valve adjustment signal Hop
en1 is input from the arithmetic processing unit 63 to the first supply servo valve 36 and the first discharge servo valve 35 via the D / A conversion unit 69, respectively, and the air pressure of the first air chamber 27 and the second air chamber 28 is increased. The air pressure in the first air chamber 27 is adjusted so that the difference becomes the pressure difference command value Href ^* .

FIG. 16 is a flow chart for explaining the subroutine of the pressure difference command distribution control process.

When the pressure difference command value Href ^* is input (S61), if the polarity of the pressure difference command value Href ^* is positive (S62), the pressure difference command value Href ^* is divided by the original pressure H3 and the 1 air chamber supply signal Hk 1 is calculated (S63),
The pressure difference command value Href ^* is subtracted from the first air chamber air pressure feedback value H1 ^* , and when the value is positive, the first air chamber discharge signal He1 is calculated (S64). Then, a shutoff signal Hclose 2 (S for closing the second supply servo valve 38)
65) and a second valve adjustment signal Hopen2 for adjusting the pressure difference between the first air chamber and the second air chamber to be the pressure difference command value Href ^* (S66), and the first air chamber supply signal is generated. Hk 1 to the first supply servo valve 36
The air chamber discharge signal He1 is sent to the first discharge servo valve 35.
To the shutoff signal Hclose 2 to the second supply servo valve 39.
To the second ejection servo valve 38 (S67). If the polarity of the pressure difference command value Href ^* is negative (S62), the sign of the pressure difference command value Href ^* is reversed (S6).
8), divide by the original pressure H3 to calculate the second air chamber supply signal Hk2 (S69), subtract by the pressure difference command value Href ^* with the second air chamber air pressure feedback value H2 ^* , and when the value is positive, the second The air chamber discharge signal He2 is calculated (S70). The shutoff signal Hclose 1 (S71) for closing the first supply servo valve 36 and the first for adjusting the pressure difference between the first air chamber and the second air chamber to the pressure difference command value Href ^* . 1 valve adjustment signal Hopen1 is generated (S7
2), the second air chamber supply signal Hk 2 to the second supply servo valve 39, the second air chamber discharge signal He2 to the second discharge servo valve 38, and the cutoff signal Hclose 1 to the first supply servo valve 36. To the first valve adjustment signal Hopen1
It transmits to each discharge servo valve 35 (S7).
3).

[0079]

As described above, in the resistance welding apparatus of the present invention, the air pressure in the first air chamber is adjusted by the first air supply means and the first air discharge means, and the second air supply means and the second air are further adjusted. Since the air pressure of the second air chamber is adjusted by the discharging means, the pressure difference between the first air chamber and the second air chamber can be set precisely, so that the pressure applied to the electrode tip can be accurately optimized. When the electrode tip is used to rapidly pressurize or release the object to be welded, the air pressure in the first air chamber and the second air chamber can be quickly changed by the first supply / discharge means and the second supply / discharge means. As a result, the welding work time can be shortened, and since the pressure applied to the electrode tip can be accurately optimized, the welding quality can be improved by eliminating the perforation of the workpiece.

The resistance welding apparatus of the present invention comprises the first air supply means and the first air supply means controlled by the piston position control means.
The air discharge means adjusts the air pressure of the first air chamber detected by the first air pressure detection means, and the second air supply means and the second air discharge means detect the second air pressure of the second air chamber. Since the air pressure is adjusted, the pressure difference between the first air chamber and the second air chamber can be set quickly and precisely. When the electrode tip is used to rapidly pressurize or release the object to be welded, the first air supply and discharge means and the second supply and discharge means controlled by the piston position control means quickly provide the first air chamber and the second air chamber. Since the air pressure in the chamber can be changed, the welding work time can be further shortened, and the welding pressure can be accurately optimized so that there is no hole in the work piece and the welding quality is improved. Can be made.

In the resistance welding method of the present invention, a nonlinear loss such as a change in air pressure is modeled to perform a quantitative calculation to compensate for the nonlinear loss, and the air pressure applied to the piston is adjusted so that the electrode tip is used to cover the loss. The position of the piston can be moved accurately and swiftly so that the force required to press the welded object or release it from the object to be welded by the electrode tip can be accurately and swiftly shortened, and the welding work time can be shortened and the electrode tip can be shortened. Since it is possible to accurately optimize the pressing force of the welding target, it is possible to improve the quality of welding by eliminating the perforation of the workpiece.

In the resistance welding method of the present invention, a nonlinear loss such as a change in air pressure is modeled to quantitatively calculate and compensate for the nonlinear loss, and the air pressure applied to the piston is adjusted to cover the electrode tip. When moving to the welded object or moving the electrode tip from the welded object, the moving speed of the piston can be moved exactly at a desired speed, so that the welding work time is shortened.

In the resistance welding method of the present invention, a nonlinear loss such as a change in air pressure is modeled to perform a quantitative calculation to compensate for the nonlinear loss, and the air pressure applied to the piston is adjusted so that the electrode tip is covered. By freely changing the pressure applied to the object to be welded when applying pressure to the object to be welded, it is possible to improve the quality of welding by eliminating holes in the object to be welded.

In the resistance welding method of the present invention, when the electrode tip is pressed against the object to be welded, the first air flow port controlled by the piston position control means is connected to the first air flow port.
The air pressure of the first air chamber is rapidly increased by the air supply / exhaust means, and the air pressure of the second air chamber is rapidly reduced by the second air supply / exhaust means connected to the second air circulation port, so that the electrode tip can quickly operate. Since the object to be welded can be pressurized, the welding work time is shortened.

According to the resistance welding method of the present invention, when the electrode tip is opened to the object to be welded, the first air circulation port controlled by the piston position control means is connected to the first air circulation port.
The air pressure in the first air chamber is rapidly reduced by the air supply / discharge means, and the air pressure in the second air chamber is rapidly increased by the second air supply / discharge means connected to the second air circulation port, so that the electrode tip quickly Since the object to be welded can be opened, the welding work time is shortened.

[Brief description of drawings]

FIG. 1 is a drawing for explaining a configuration of a pneumatic circuit section of a resistance melting apparatus of the present invention.

FIG. 2 is a drawing for explaining a configuration of an electric circuit portion of the resistance welding device of the present invention.

FIG. 3 is a flow chart for explaining control of the resistance welding apparatus of the present invention.

FIG. 4 is a block diagram for explaining a disturbance observer of the resistance welding device of the present invention.

FIG. 5 is a flow chart for explaining control of a disturbance observer of the resistance welding device of the present invention.

FIG. 6 is a block diagram for explaining a positioning mode of the resistance welding device of the present invention.

FIG. 7 is a graph showing changes in a speed reference value and a pressure command value processed inside the resistance welding apparatus of the present invention.

FIG. 8 is a flowchart for explaining a subroutine of a positioning mode process of the resistance welding device of the present invention.

FIG. 9 is a block diagram for explaining a speed control mode of the resistance welding device of the present invention.

FIG. 10 is a flowchart for explaining a subroutine of speed control mode processing of the resistance welding apparatus of the present invention.

FIG. 11 is a block diagram for explaining a positioning mode of the resistance welding device of the present invention.

FIG. 12 is a flow chart for explaining a subroutine of a positioning mode process of the resistance welding device of the present invention.

FIG. 13 is a block diagram for explaining a full-open pressure release mode of the resistance welding device of the present invention.

FIG. 14 is a flow chart for explaining a subroutine of a full-open pressure release mode process of the resistance welding apparatus of the present invention.

FIG. 15 is a block diagram for explaining a pressure difference command distribution unit of the resistance welding device of the present invention.

FIG. 16 is a flow chart for explaining a subroutine of processing of pressure difference command distribution control of the resistance welding apparatus of the present invention.

FIG. 17 is a flow chart for explaining a subroutine of processing of pressure difference command distribution control of the resistance welding apparatus of the present invention.

FIG. 18 is a drawing for explaining the configuration of a conventional resistance welding device.

[Explanation of symbols]

2 ... Electrode tip, 3 ... Object to be welded, 21 ... Air circuit part, 2
3 ... Piston, 25 ... Cylinder, 27 ... First air chamber, 2
8 ... 2nd air chamber, 29 ... Shaft, 35 ... 1st discharge servo valve, 36 ... 1st supply servo valve, 37 ... 1st electromagnetic valve, 38 ... 2nd discharge servo valve, 39 ...
Second supply servo valve, 41 ... Second electromagnetic valve, 53
... Piston position detection sensor, 63 ... Calculation processing unit, 81 ...
Disturbance observer, 91 ... Positioning mode, 101 ... Velocity control mode, 111 ... Pressurization control mode, 121 ... Full open pressurization release mode, 131 ... Pressure difference command distribution unit.

Claims (7)

[Claims] 1. A first space in the cylinder is formed by the piston.
A rod-shaped shaft, which is divided into an air chamber and a second air chamber, is fixed to the piston so as to pass through the piston and the cylinder and move with the movement of the piston, and an object to be welded at an end of the shaft. In a resistance welding apparatus provided with an electrode tip for pressurizing and resistance welding, a first air circulation port and a first air circulation port are provided on both side surfaces of the cylinder for circulating air into the first air chamber and the second air chamber, respectively. A first air discharging means for discharging the air in the first air chamber to the outside so that the electrode tip is separated from the object to be welded, First air supply means connected to the first air discharge means by an air pipe and supplying air to the first air chamber so that the electrode tip pressurizes an object to be welded; and the first air flow. The first opening is connected to the opening by an air pipe.
First air supply / exhaust means for supplying / exhausting air to / from the air chamber, and the second air circulation port are connected by an air pipe, and the air in the second air chamber is externally connected so that the electrode tip pressurizes the workpiece. Second air discharging means for discharging to the second air discharging means, and second air supplying means connected to the second air discharging means by an air pipe and supplying air to the second air chamber so that the electrode tip is separated from the object to be welded. , The second air circulation port is connected by an air pipe,
A second air supply / discharge means for supplying or discharging air to / from the air chamber. 2. The first space in the cylinder is defined by the piston.
A rod-shaped shaft, which is divided into an air chamber and a second air chamber, is fixed to the piston so as to pass through the piston and the cylinder and move with the movement of the piston, and an object to be welded at an end of the shaft. In a resistance welding apparatus provided with an electrode tip for pressurizing and resistance welding, a first air circulation port and a first air circulation port are provided on both side surfaces of the cylinder for circulating air into the first air chamber and the second air chamber, respectively. 2 first air pressure detection means that is provided with an air circulation port, is connected to the first air circulation port by an air pipe through which air flows, and detects the pressure of the air in the first air chamber; and the first air pressure detection means. A first air discharge means connected to the air pipe for discharging the air in the first air chamber to the outside so that the electrode tip is separated from the object to be welded; and the first air discharge means and the air pipe. First air supply means for supplying air to the first air chamber so that the electrode tip pressurizes the object to be welded, and the first air circulation port and the air pipe for connection.
A second air pressure detection unit that is connected to a first air supply / discharge unit that supplies or discharges air to / from the air chamber, and that is connected to the second air circulation port by an air pipe through which air circulates, and that detects the pressure of the air in the second air chamber. Means, second air discharge means for connecting the second air pressure detection means by an air pipe, and discharging the air in the second air chamber to the outside so that the electrode tip pressurizes the object to be welded, and the second air A second air supply unit connected to the discharge unit by an air pipe and supplying air to the second air chamber so that the electrode tip separates from the object to be welded; and a second air discharge unit connected to the second air chamber by the air pipe, Second air supply / discharge means for supplying or discharging air to the second air chamber, the first air supply means, the first air supply / discharge means, the second air supply means, and the second air supply / discharge means By air tube It is continued, the first air supply means, the first air supply outlet means, a third that detects the air pressure supplied to the second air supply means and the second air supply outlet means
Air pressure detecting means, piston position detecting means for detecting the position of the piston, and the first air pressure detecting means, the second air pressure detecting means, the third air pressure detecting means, and the piston position detecting means. And a piston position control means for varying the air pressures of the first air chamber and the second air chamber to move the piston to a desired position. 3. A first space in the cylinder is created by the piston.
A rod-shaped shaft that is divided into an air chamber and a second air chamber, is fixed to the piston so as to pass through the piston and the cylinder, and moves with the movement of the piston, and a welded object provided at an end of the shaft. An electrode tip for pressurizing and resistance welding an object, and air pressure in the first air chamber,
The air pressure of the second air chamber and the position of the piston are detected, the air pressures of the first air chamber and the second air chamber are varied, and the piston is moved to a desired position so as to be optimally welded by the electrode tip. In a resistance welding device including piston position control means, a loss generated when the piston moves is separated into a linear loss and a non-linear loss, a model of the separated non-linear loss is modeled, and the modeled non-linear loss is modeled. A non-linear loss is calculated from the loss generation circuit of 1., the calculated non-linear loss is compensated, and the piston is moved to a desired position. 4. The first space in the cylinder is formed by the piston.
A rod-shaped shaft that is divided into an air chamber and a second air chamber, is fixed to the piston so as to pass through the piston and the cylinder, and moves with the movement of the piston, and a welded object provided at an end of the shaft. An electrode tip for pressurizing and resistance welding an object, and air pressure in the first air chamber,
Piston position for moving the piston to a desired position so that the air pressures of the first air chamber and the second air chamber are varied depending on the air pressure of the second air chamber and the position of the piston so that welding can be performed optimally by the electrode tip. In a resistance welding device comprising a control means, the loss generated when the piston is moved is separated into a linear loss and a non-linear loss, the separated non-linear loss generating circuit is modeled, and the modeled generating circuit is used. A resistance welding method comprising calculating a nonlinear loss, compensating the calculated nonlinear loss, and moving the piston at a desired speed. 5. The first space in the cylinder is formed by the piston.
A rod-shaped shaft that is divided into an air chamber and a second air chamber, is fixed to the piston so as to pass through the piston and the cylinder, and moves with the movement of the piston, and a welded object provided at an end of the shaft. An electrode tip for pressurizing and resistance welding an object, and air pressure in the first air chamber,
The air pressure of the second air chamber and the position of the piston are detected, the air pressures of the first air chamber and the second air chamber are varied, and the piston is moved to a desired position so as to be optimally welded by the electrode tip. In a resistance welding device comprising piston position control means, a loss generated when the piston moves is separated into a linear loss and a non-linear loss, and a model of the separated non-linear loss generation circuit is modeled. A resistance welding method comprising calculating a non-linear loss from a circuit, compensating the calculated non-linear loss, and pressurizing an object to be welded with a desired pressing force by the electrode tip. 6. At the time of maximum pressurization of the piston, the first air supply / discharge means is fully opened to supply air to the first air chamber, and the air is discharged from the second air chamber to the outside. The resistance welding method according to claim 1, wherein the second air supply / discharge means is fully opened for discharge. 7. When the piston is fully opened, the first air supply / exhaust means is fully opened to exhaust air from the first air chamber to the outside, and the air is supplied to the second air chamber. The resistance welding method according to claim 1, wherein the second air supply / discharge means is fully opened.