JPH07115205B2 - Electrode pressure measuring device for resistance welding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrode device for measuring or monitoring the electrode pressure of a resistance welding machine.

(Prior art) In resistance welding, an object to be welded is sandwiched by an appropriate pressure force through electrodes, and then a welding current is passed through the welding electrodes.
The welded part is melted by heating and pressed.

In resistance welding, it is desirable to start heating by applying welding current after the welding pressure reaches the set pressure. Similarly, when the weld reaches a molten state sufficient for welding and the welding current is cut off, it is desirable to release the pressure contact force after the weld has cooled to an appropriate temperature.

Therefore, in a commonly used pressurizing device using fluid pressure, if there is a time delay element in the fluid switching solenoid valve and the fluid circuit, the welding pressure reaches the set pressure in order to improve work efficiency in normal welding work. The solenoid valve may be switched at the same time when the energization is stopped.

These operation commands are given by the resistance welding control device, but most of the measuring methods of the electrode pressing force required for the setting are
For example, as shown in FIG. 1, a pressure gauge is inserted into electrodes 22 and 23, and the pressure gauge 21 is sandwiched by the electrodes and the static pressure contact force generated in the pressure gauge 21 is measured by a dial gauge 24.

Recently, for example, as shown in FIG. 2, a method is known in which a strain gauge 25 is directly attached to an electrode arm 27 of a spot welding gun 26 to measure the electrode pressing force from the strain of the arm.

Further, as shown in FIG. 3, a strain gauge type pressure transducer 29 having a built-in small voltage amplifier 28 is inserted into the movable portion of the spot welding gun 26 to detect both the electrode pressing force and the welding current by an electromagnetic oscilloscope or a data recorder. A measurement method of storing the data in the same manner has been attempted.

(Problems to be solved by the present invention) However, the above-mentioned welding pressure gauge cannot only measure the dynamic welding force required at the welding site, that is, the welding current flow timing. Instead, it is dangerous to hold the pressure gauge by hand.

In addition, other strain gauges are not susceptible to shocks and spatter during welding and do not last long. Moreover, in the case of a pressure transducer, not only is the device large-scaled, but since it is measured close to a large current circuit of several thousand amperes to tens of thousands of amperes, it is affected by the noise generated by electromagnetic induction, and the true pressure is applied. Pressure measurement was difficult.

Therefore, the present invention can directly obtain a true measured value of the electrode pressing force at the welding time of resistance welding, and improves the accuracy of the time setting of the electrode pressing force and the welding current for obtaining the optimum welding quality. The purpose is to contribute.

(Means for Solving the Problem) In order to achieve the above object, in the present invention, a pressure force at the time of electrode pressure is applied to or around the pressure center of the electrode of the resistance welding machine, and the applied pressure force is applied. In a device that measures the electrode pressure by converting the output voltage to output voltage through piezoelectric action, when the surface receives mechanical energy when the electrode is pressed inside the electrode of a resistance welding machine, this is converted into electrical energy. Provided is an electrode device in which a sensor that converts and generates an electric quantity according to a pressing force is built in via an insulating material.

(Function) According to the device of the present invention, by only incorporating the sensor inside the electrode via the insulating material, it is possible to prevent spatter adhesion from the outside, and to be free from the influence of noise due to electromagnetic induction from the inside. It is possible to obtain a true measured value, and it is possible to remarkably improve the setting accuracy of the pressing force.

(Example) Hereinafter, a specific example of the apparatus according to the present invention will be described with reference to FIGS.
Description will be given with reference to the drawing of FIG.

Fig. 4 shows a cross section of the electrode device of the spot welding machine. In the figure, a holder 2 is fixed to the lower side of a supporting member of an electrode device 1, a screw adapter 4 is screwed into a screw hole 3 of this holder, and a shank 6 is fitted into an insertion hole 5 of this adapter.

The shank 6 is divided into two in a direction intersecting with the electrode pressing wire Y, and one shank 6a and the other shank 6b have circular recesses 7 on the sides facing each other on the same pressing wire. Has been formed.

The shank 6a and the shank 6b are fixed by a tightening bolt 8 and a tightening adjustment bolt 10 inserted through an insulating pipe 9. The electrode tip 11 is inserted at the tip of the shank 6b.

A sensor 12 having a lead wire 14 drawn out is inserted into the circular recess 7 through an insulating material 13.

This sensor 12 may be generally commercially available. For example, when a surface receives a force when the electrode is pressed, a special material that converts its mechanical output into an electric quantity by the piezoelectric effect and generates an output voltage to the outside. It has a structure using.

The amount of electricity output from this sensor 12 is detected and displayed on a digital display (not shown) for checking, or it is introduced into a computer device, etc. Judgment monitoring is also possible.

A cooling water circulation passage 15 and a cooling water circulation passage 16 are formed inside the holder 2 and the shank 6 to prevent the temperature of the electrodes from rising.

Next, FIG. 5 shows an example of the case where the sensor 12 is provided around EE on the electrode pressing line.

In this case, the sensor 12 is installed on the outer periphery of the intermediate holder 18 fitted in the pressurizing cylinder rod 17, and is inserted via the insulating material 13 between the sensor 12 and the point holder 19 fitted in the intermediate holder.

Next, FIG. 6 shows an example in which the sensor 12 is inserted into the point holder 19 and the intermediate holder 18 of the pressure cylinder rod 17 on the same center line Y. In this case, the point holder 19
The insulating material 13 is inserted into the concave portion 20 provided in the pressure sensor, the sensor 12 is installed in the insulating material, and the pressure cylinder rod is inserted from above the sensor into the concave portion of the point holder 19 via the intermediate holder 18.
17 is inserted.

Next, FIG. 7 shows another structural example in which the sensor 12 is incorporated in the recess 20 of the point holder 19 via the insulating material 13, and the cylinder rod 17 is inserted from above the sensor.

In this case, the sensor 12 has a structure in which the pressure is directly received from the cylinder rod 17 on the center line of pressure.

In the above configuration, when the start button of the spot welder is pressed, the solenoid valve switches, the welding head descends, the upper electrode comes into contact with the workpiece, and the pressure gradually rises.
When pressure is applied to the surface of the sensor, the piezoelectric effect of the sensor produces an electric charge according to the applied pressure, and outputs a voltage to the outside. This electrical output can be measured or monitored by processing it through other equipment.

On the other hand, when the squeeze time preset in the control unit elapses after the solenoid valve is switched when the predetermined pressure is reached, the thyristor of the main power supply is turned on to start energization and enter the energization time.

When the energization time is completed, the main thyristor turns off and the voltage between the electrodes disappears. At the same time, the holding time is entered to hold the welded part for a set period of time. When this holding time is completed, the solenoid valve is switched and the pressure contact force is gradually reduced until the electrode is opened and the sensor output returns to the state before pressurization.

Note that even if a large current flows through the electrodes, the sensor is insulated, so there is no electrical effect and only a mechanical load is applied.

(Effects of the Invention) As described above, according to the apparatus of the present invention, the true electrode force can be measured or monitored without any trouble during electrode welding during electrode welding. In addition, by simply incorporating a sensor utilizing the piezoelectric effect on or around the electrode pressurizing wire in an insulated state, the sensor can be prevented from spattering from the outside or electrical troubles due to electromagnetic induction from the inside. Can be obtained.

Therefore, according to the present invention, since it is possible to improve the setting accuracy of the sufficient pressing force for obtaining the optimum welding quality, it is possible to easily set the time such as the squeeze time in the sequence control. Produce an effect.

[Brief description of drawings]

FIG. 1A is a plan view showing a dial gauge type electrode pressure gauge used in a conventional pressure measuring method. Figure 1B is the side view. FIG. 2 is a schematic view of a pasting type strain gauge used in a spot welding gun. FIG. 3 is a schematic view when a conventional strain gauge type pressure transducer is used for a spot welding gun. FIG. 4 is a sectional view showing an electrode device of a spot welding machine of the device of the present invention. 5 to 7 are sectional views of an electrode device showing another embodiment of the present invention. 1 ... Electrode device, 12 ... Sensor 13 ... Insulation material

Claims (1)

[Claims] 1. A pressurizing center of an electrode of a resistance welding machine or its periphery receives a pressurizing force at the time of pressurizing the electrode, and the applied pressurizing force is converted into an electric output through a piezoelectric action to change the pressurizing force of the electrode. A device for measuring, in which the mechanical energy at the time of electrode pressure is applied to the surface of the electrode of a resistance welding machine to convert the electrical energy into electrical energy and generate an electric quantity according to the applied pressure. Electrode pressure measuring device for resistance welding machine built in via insulating material.