JPS603908B2 - High frequency resistance spot projection welding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high frequency resistance spot projection welding machine.

Conventional resistance welding machines of this type are classified into alternating current type, capacitor type, rectification type, and low frequency type based on the welding current delivery method, and each type has the following characteristics.

■ The AC type is a commonly used method because the structure of the welding machine is simple, the price is low, and resistance welding can be performed over a wide range of areas.

Advanced control devices are currently being manufactured that can control welding current in various ways, but because the basic frequency uses a power source with a commercial frequency, the minimum time unit for current control is 1/2 of the commercial frequency. This becomes a cycle, and control in a shorter period of time is impossible. ■ Capacitor type welding machines are manufactured from small to large sizes, and various welding conditions are performed by changing the welding current by changing the charging voltage of the capacitor and the turns ratio of the welding transformer.

However, since the welding current is generated by discharging the charge stored in the capacitor, in order to obtain a welding current that rises quickly, the actance must be reduced from the primary side of the welding transformer. The welding transformer becomes larger and the shape of the transformer secondary conductor becomes constrained.

Furthermore, a welding current with a slow rise has limitations, such as the inability to effectively utilize the energy stored in the capacitor.

■ For the rectifier type and low frequency type, the minimum controllable time unit is 1'2 cycles of the commercial frequency, just like the AC type.
Control over a shorter period of time is not possible.

The rise time of the welding current is determined by the shape of the secondary conductor of the welding machine, the reactance of the rectifier circuit, and the reactance of the transformer.It is possible to slow down the rise of the current using a control device, but to make it faster, it is possible to This is difficult due to the constraints of
Therefore, it is an object of the present invention to provide a high frequency resistance spot projection welding machine that expands the scope of conventional welding by enabling welding that was difficult or impossible with the conventional methods described above. shall be.

Embodiments of the welding machine of the present invention will be described below with reference to the drawing of FIG.

In the figure, 1 is a commercial frequency power supply, 2 is a converter that converts AC to DC, 3 is a variable resistor that adjusts the welding current, 4 is an inverter that converts DC to high frequency, and 5 is a high frequency output time setting. A variable resistor 6 is a variable resistor for adjusting the slope, 7 is a high frequency welding transformer, and 8 is a conductor connecting the secondary side of the transformer 7 to the spot or projection electrode 9 and the workpiece 10. . Although not shown, it is equipped with a pressure mechanism as a resistance welder. The power source 1, converter 2, inverter 4, transformer 7, electrode 9, and workpiece 10 are connected in series as shown in the figure, and the variable resistor 3 is provided in the converter 2, and the variable resistors 5 and 6 are provided in the inverter 4. It is being Then, the converter 2 converts the commercial frequency alternating current of the power source 1 into direct current, the inverter 4 converts the direct current into a high-frequency current, and the high-frequency current is further converted into an appropriate welding current by the transformer 7 and supplies it to the electrode 9. Then, the workpiece 10 is subjected to spot welding or projection welding.

Of course, the welding current is adjusted by the variable resistor 3, the high frequency output time is set by the variable resistor 5, and the slope is adjusted by the variable resistor 6, respectively. The high frequency welding machine of the present invention constructed as described above has the following features. As shown in Figure 2, the minimum controllable unit time is shorter than that of the conventional methods shown in Figures 3 to 6, so the rise (angle a in each figure) is faster (the rise angle is right angle Welding current (close to ) can be passed through the workpiece,
In addition, since it is possible to control the current of each cycle of high frequency to produce various slope currents (up slope and down slope) as shown in Fig. 7, waveforms ranging from those with fast rises to conventional waveforms can be used. This makes it suitable for welding materials with good heat conductivity, thin materials, protruding shapes, small items, etc.

Note that FIG. 3 shows the current for one cycle of the commercial frequency in an AC type.

lw is the effective value of welding current, and a is the rising angle. FIG. 4 shows the welding current of the capacitor type, FIG. 5 shows the welding current of the three-phase full-wave rectification type, and FIG. 6 shows the welding current of the three-phase low-frequency type. (2) If an inverter that converts the high frequency voltage into a square wave is used as the power source that converts the voltage into a high frequency voltage, energy with good thermal efficiency as shown in FIG. 8 can be applied to the workpiece.

In other words, the eighth point is that the high-frequency type waveform A is more efficient in providing thermal energy to the workpiece than the AC type waveform B.
The figure shows. {31 Due to the higher frequency, the welding transformer is 4-type compared to the conventional type, and depending on the capacity, it can be built into the pressure mechanism of the welding machine, making it possible to manufacture a welding machine with good workability and efficiency. be.

[4] It has better thermal efficiency than the secondary type, so there is less heat influence on areas other than the welded area.

As described above, according to the present invention, it is possible to provide a high frequency resistance spot projection welding machine having various features.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of a welding machine according to the present invention;
Fig. 2 is a welding current waveform diagram of the welding machine, Figs. 3 to 6 are welding current waveform diagrams of the subordinate welding machine, Fig. 7 is a slope current waveform diagram of the welding machine of the present invention, and Fig. 8 1 is a welding current comparison diagram of a welding machine according to the present invention and an AC welding machine. 1...Commercial frequency power supply, 2...AC-DC converter (converter), 3, 5, 6...Variable resistor, 4...DC-high frequency converter (Imba-Yu),
7... High frequency welding transformer, 8... Connection conductor, 9... Electrode, 10... Welding object. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. A high-frequency power supply device that converts the commercial frequency power source into a welding current power source in a resistance welding machine and can perform various controls necessary for welding by converting it to high frequency, and a high-frequency welding transformer that converts the high-frequency power source into the current necessary for welding. A high-frequency resistance spot projection comprising: an electrode for pressurizing and energizing a workpiece to be welded; and a pressurizing mechanism including a conductor connecting the electrode and the high-frequency welding transformer. Welding machine.