JPS608914B2 - Battery-powered resistance welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resistance welding device, and more particularly to a blowout prevention device for a resistance welding device that uses a constant voltage DC welding power source powered by a storage battery.

In general, a storage battery type welding power source can set a wide range of welding energy, that is, voltage and time by combining it with a timer for setting the energization time, even though the current is small. It is used for welding the upper conductor and ultra-fine wire, or for welding ultra-fine wire of several tens of microns or foil together.

For example, there is a welding power source disclosed in Japanese Patent Publication No. 42-2402, which adds functions of more precise output control and better reproducibility to such a storage battery type welding power source.

This welding power source uses a constant voltage method to detect changes in conditions during the welding process by changes in the voltage value between the welding electrodes, and compares this with a preset reference voltage to obtain a control signal that represents the difference between the two voltages. . The welding current is corrected as needed based on this control signal, and an appropriate value is always supplied to the welding material. According to this welding power source, it is possible to perform relatively stable welding while minimizing the thermal effect on the welding material and preventing accidents such as overheating and melting of the welding material to a certain extent. There was a drawback that the welding output was under controlled due to the influence of

In addition, such welding power sources are often used for welding small items such as ribbons, microcircuit wires, and printed circuit conductors because welding energy, that is, voltage and energization time can be set over a wide range. Taking as an example the case of welding a gold-plated steel IJ bond, the range in which good welding results can be obtained is between 30 and 40 V at the interelectrode voltage (thickness 70R, using copper foil on the middle 0.3 side). (if there is one) This is because copper foil has very good thermal conductivity, and if the amount of heat input to the welding part is even slightly insufficient, the copper and gold will not melt, and therefore welding will not be possible. In addition, copper and gold form an alloy from 88900, but if the temperature increases by about 200 qo, it will melt. Therefore, if the amount of heat input to the welding part is even slightly too large, the melting point will be exceeded and the copper foil will melt. This also causes the gold-plated copper ribbon to scatter, resulting in poor welding. Furthermore, because printed circuit conductors are manufactured using an etching method, their size varies by about 20 to 25%, and the electrode spacing may change due to dirt on the electrode tips or wear and tear on the electrode tips. Considering changes in the welding area, etc., there was a problem in that good welding results could not be obtained even if the various controls described above were performed. An object of the present invention is to monitor the resistance value between welding electrodes during welding, and when the resistance value exceeds a predetermined value, to urgently stop the welding current to prevent melting of the welding material, thereby achieving good welding. The aim is to provide a fusing prevention device that leads to results.

The storage battery type resistance welding device of the present invention detects a change in welding conditions in the welding saddle, compares it with a variable reference voltage set in advance, obtains a control signal representing the difference, and performs welding using this control signal. In a storage battery-type resistance welding device that corrects the current and supplies an appropriate welding current to the welding material, a means for comparing the resistance value between both electrodes detected during welding with a preset reference resistance value for stopping energization. and an energization stopping means for cutting off the welding current when the comparison result exceeds a reference resistance value. Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In the figure, numeral 11 is a timer that generates an output pulse for arbitrarily adjusting the welding current application time. The output signal from the timer 11 generates a reference voltage for supplying welding energy according to the welding material.The output voltage from the reference voltage generator 12 is a feedback signal whose other input represents the voltage between the welding electrodes. It is applied to one input side of a certain voltage comparator 13. The voltage comparator 13 compares the welding electrode voltage with the reference voltage and outputs a control signal representing the difference between the reference voltage and the feedback voltage. The control signal from voltage comparator 13 is amplified by DC amplifier 14 and then applied to current controller 15 . The current controller 15 is connected to a closed circuit consisting of a pair of welding electrodes 1 and 2 that are to be in contact with the welding material 3 and a storage battery 16 . The voltage appearing between the flash electrodes 1 and 2 is fed back via a lead 17 to a voltage comparator 13 for comparison with a reference voltage. A welding current detector 21 is inserted into a closed circuit through which welding current flows, and detects a voltage corresponding to the welding current.

The detected voltage is amplified by an amplifier 22 and applied to an arithmetic gate circuit 23 whose other input is a feedback signal of the voltage between welding electrodes 1 and 2 generated during welding. The voltage between welding electrodes is amplified by an amplifier 25 via a lead 24 and applied to an arithmetic gate circuit 23. The gate controller 26 is
A voltage comparator detects that there is an output voltage between the welding electrodes, and controls opening and closing of the arithmetic gate circuit 23. In conjunction with the operation of the gate controller 26, the calculation gate circuit 23 outputs or cuts off the input welding current (voltage proportional to it) and inter-electrode voltage to the resistance calculation device 27 at the next stage. The resistance calculator 27 divides the inter-electrode voltage by (a voltage proportional to) the welding current to obtain a voltage proportional to the resistance between electrodes 1 and 2.
It is output as one input of comparator 28. Further, the comparator 28 receives an output signal from the energization stop reference setting device 29, which is preset to a voltage corresponding to the resistance value between the welding electrodes at which the energization should be stopped, as determined by the material and size and shape of the welded object. is input. The setting voltage of the reference setter 29 is
For example, when welding the copper foil of an ordinary printed circuit board and a gold-plated steel ribbon, the voltage is set to correspond to a Q of 2 to 3, and in the case of a gold-plated cover ribbon, a voltage corresponding to a Q of 5 to 6 is set. The comparator 28 compares a voltage input proportional to the resistance between the electrodes with a preset energization stop reference voltage, and when the voltage input exceeds the reference voltage, a signal is sent to the energization stop circuit 31 and the alarm gate 32. Output. The input to the energization stop circuit 31 is set by setting a bistable multi-vibrator (not shown) that constitutes the energization stop circuit 31, and outputs a energization stop signal to the DC amplifier 14 to cut off the output of the DC amplifier 14. to forcibly stop the welding current. This bistable multi-
The piperator is reset by the expiration of the timer. The other output of the energization stop circuit 31 is input to a display 33 composed of an LED or the like, and indicates that the energization stop circuit 31 is activated and the welding current is stopped. This indicator 33 lights up when the resistance value between the welding electrodes exceeds a predetermined resistance value, so it is difficult to determine whether the cause (timing) is a defect after nugget formation or a defect before nugget formation. Not stick. For this reason, an alarm timer 34 consisting of a monostable multi-pipulator or the like that is activated by a welding command is provided, and outputs a signal to open the alarm gate 32 only for a short time until nugget formation begins. The alarm gate 32 outputs an output and activates the alarm 35 only when the input from the comparator 28 and the input from the alarm timer 34 are received at the same time. The alarm 35 is composed of a bistable multi-pipulator, etc., and uses an LED display or a buzzer to notify that a welding failure has occurred before nugget formation. If this warning occurs, remove the cause of the failure and
Re-welding can be performed. As is clear from the above explanation, the storage battery-type resistance welding device of the present invention monitors the resistance value between the welding electrodes, and when the resistance value exceeds a predetermined level, the energization is stopped immediately. It is possible to prevent welding materials from melting, blowing up, etc.

In addition, since it detects abnormalities in the resistance value between the welding electrodes at the initial stage of energization and before a nugget begins to form, the energization is stopped. It is also possible to prevent the occurrence of defects due to insufficient growth of the nugget due to misalignment, etc., and it is possible to lead to good welding results.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of a storage battery type resistance welding device according to the present invention. In the figure, 21... Welding current detector, 22, 25...
...Amplifier, 23...Arithmetic gate circuit,
26... Gate controller, 27... Resistance calculator, 28... Comparator, 29... Energization stop reference setter, 31...・・Electrification stop circuit, 3
2...Alarm gate, 33...Display device, 34
...Alarm timer, 35...Alarm device.

Claims (1)

[Claims] 1. Detects changes in welding conditions during welding, compares them with a preset variable reference voltage, obtains a control signal representing the difference, corrects the welding current using this control signal, and adjusts the welding current to the appropriate welding material. In the storage battery type resistance welding device, the welding current detection means detects a voltage proportional to the welding current from a closed circuit through which the welding current flows, and the voltage detected by the detection means and the change in welding conditions during welding are detected as changes in the welding conditions. means for extracting a voltage proportional to the resistance value between the welding electrodes from the welding electrode voltage; energization stop reference setting means for presetting a voltage corresponding to the resistance value at which the welding current should be stopped; and the energization stop reference voltage. and a voltage proportional to the resistance value between the welding electrodes; energization stop means for cutting off the welding current when the comparison result exceeds a energization stop reference value; 1. A storage battery type resistance welding device, characterized in that it is provided with an alarm means that issues an alarm when an input is made.