JP2577621B2 - Resistance welding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a resistance welding machine, and more specifically, to display signal waveforms from a means for detecting an electrode pressing force of a resistance welding machine and a means for detecting a welding current. The present invention relates to a welding machine in which the mechanical and electrical characteristics unique to the welding machine are visually observed to enable the setting of true welding conditions suitable for the mechanical or electrical characteristics unique to each welding machine.

(Prior art) Normally, in spot welding, an object to be welded is inserted between upper and lower electrode tips of a spot welding machine, the object to be welded is pressurized by the upper and lower electrode tips, and a predetermined welding current is applied for a required time to form a weld. Heated and melted.

The rise time of the electrode pressing force in spot welding is not constant even in welding machines manufactured with the same rating due to variations in mechanical system operation and the like.

Normally, the welding force required for welding is inserted into the electrode pressing section from the outside with the power supply between the electrodes cut off, and the electrode force is applied to the measuring device to apply the electrode force to the machine. It is common to measure a pressure waveform.

(Problems to be Solved by the Invention) Conventionally, a device for setting and displaying welding conditions of resistance welding is:
Welding conditions such as pressing force, welding current, and energizing time only display the set values and the numerical values of the detected data. The welding current waveform could not be displayed simultaneously with the graphic. Therefore, the setting of the welding conditions to the control device must rely on intuition based on the empirical rules of the operator.

(Means for Solving the Problems) The present invention has been made to solve the problems described above, and a specific configuration thereof is a resistance welding machine for welding an object to be welded via an electrode. , The welding force such as the welding force, welding current, energizing time, etc., is set, and based on these control elements, the device for controlling the mechanical and electrical operations necessary for welding detects the above welding force. And a welding current waveform detected by these detecting means.
It is characterized in that all energization cycles or arbitrary cycle sections are designated and displayed simultaneously in graphic form.

According to such a configuration, by displaying the pressing force waveform and the welding current waveform of the resistance welding machine on a screen, it is possible to monitor the welding force characteristic unique to the welding machine and the welding current energizing timing with the same device.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is an electric block diagram showing a configuration example of the present invention.

In the configuration shown in the figure, reference numerals 1 and 2 denote electrodes for sandwiching the workpiece 3 from above and below, reference numeral 4 denotes a pressurizing cylinder for applying a pressurizing force between the electrodes, and reference numeral 5 denotes a pressurizing cylinder incorporated in a piston rod 6 of the pressurizing cylinder. Amplifier 21 and A / D converter 22 with pressure detection sensor
Is connected to the CPU 14 via the. 7 is a welding transformer,
Reference numerals 8 and 9 are secondary leads of the welding transformer, and reference numerals 10 and 11 are primary leads of the welding transformer.

Reference numeral 12 denotes a toroidal coil for detecting a welding current flowing from the secondary lead wire 11 to the workpiece 3. 13 is an integrator
It is inserted between the toroidal coil 12 and the A / D converter 15 connected to the CPU 14, integrates the output of the toroidal coil, and restores the current waveform.

Reference numeral 16 denotes a setting device for setting a welding current, a conduction time, a pressing force, and other welding conditions necessary for welding. 17 is an electromagnetic valve for pressurization installed in the fluid pressure system line to the pressurizing cylinder,
Reference numeral 18 denotes an electro-pneumatic proportional valve for setting a pressing force. Reference numeral 19 denotes two anti-parallel thyristors inserted into the primary lead wires of the welding transformer, and controls the phase of the current to the welding transformer 7 by an energizing signal from the CPU 14. 20 is a start switch. 23 is
This is a display connected to the CPU 14.

 Next, the operation will be described.

First, welding conditions such as welding pressure, welding current, conduction time, squeeze time, hold time, etc., which are optimal for welding are set by the setting unit 16, and the welding machine is started by the start switch 20. The electromagnetic valve 17 is excited, and the electrode 1,
2, the workpiece 3 is pressurized, and after a predetermined squeeze time has elapsed, a firing signal is input to the thyristor 19, and a welding current is supplied to the workpiece. After a predetermined energizing time and after a hold time, the pressure is released and welding is completed by a series of welding sequence programs.

At this time, the welding current is applied to the toroidal coil 12 and the integrator.
The waveform is shaped by 13 and stored in the memory in the CPU 14 for each half cycle by the A / D converter 15.

On the other hand, the pressure is also amplified by the pressure detection sensor 5.
After passing through 21, the data is stored in the CPU 14 by the A / D converter 22.

When the welding for each point is completed, the pressing force and welding current waveforms are displayed on the display 23 as shown in FIGS. 2A to 2B. At this time, the section to be displayed can be specified by the setting unit 16 in advance. The example in FIG. 2A is a waveform curve showing the entire energizing section from the start of pressurization to the release of pressurization.

Looking at this waveform display, the rise time of the welding force specific to this welding machine and the start of energization of the welding current are half cycle or 1 cycle.
It can be visually checked for each cycle, and if the energization start time is too late for the rise of the applied pressure, the setting can be changed and set while looking at the display screen with the setting device 16.

FIG. 2C shows a waveform example of capacitor spot welding. In this case, it is often the case that the energization is started with the aim of the forging effect in the middle of the rise of the pressurizing force. The setting can be changed on the screen so that the energization start timing is adjusted to the optimum pressurizing force rising point. FIG. 2B is an enlarged view of only the designated sample section. In this case, it is displayed so that the influence on the pressure waveform due to the thermal expansion of the welding nugget near the start of energization can be confirmed, and can also be used for analysis of welding quality.

(Effects of the Invention) As described above, according to the present invention, it is possible to simultaneously display and monitor the welding force waveform, which is the electrical characteristic, and the pressing force waveform representing the mechanical characteristics inherent to the volume machine. Optimal welding conditions can be easily set or changed in accordance with the unique characteristics of each welding machine.Even for the wear of machine elements, etc., it is possible to accurately judge and change the setting of control constants every time. Since it can be easily performed, a revolutionary resistance welding machine has emerged, such as dramatically improving the accuracy of setting welding conditions for obtaining optimal welding quality and facilitating easier welding quality control.

[Brief description of the drawings]

FIG. 1 is an electric block diagram showing a configuration example of a resistance welding machine according to the present invention. FIG. 2A is a graph showing a pressing force waveform and a welding current waveform during the entire energizing time. FIG. 2B is a graph in which a pressure waveform and a welding current waveform in an arbitrary designated cycle section are enlarged. 2nd C
The figure is a graph showing the pressing force waveform and welding current waveform of capacitor spot welding. [Explanation of References] 1, 2,..., Electrodes, 3,..., Work piece, 4, pressurized cylinder, 5, pressure detection sensor, 7, welding transformer, 12
…… Welding current detector (toroidal coil), 14 …… CP
U, 23 …… Display

Claims (1)

(57) [Claims] 1. A resistance welding machine for welding an object to be welded via electrodes, wherein welding conditions such as a welding pressure, a welding current, and a conduction time are set, and welding is performed based on these control elements. In a device for controlling necessary mechanical and electrical operations, the apparatus has both a means for detecting the pressing force and a means for detecting the welding current, and a pressing force waveform and a welding current waveform detected by these detecting means. A total welding cycle or an arbitrary cycle section is designated and displayed simultaneously in a resistance welding machine.