JPS6227909B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a welding monitor device for a capacitor discharge type stud welding machine.

In this type of stud welding machine, it is necessary to control the welding current, its energization time, and the timing of pressing the stud against the base metal.If at least these three conditions are not satisfied, welding defects may occur or welding may occur. There may be cases where this is not possible. Conventionally, inspection to see whether stud welding has been performed satisfactorily has been carried out by tapping with a hammer, etc., which requires a great deal of labor and time and is inefficient if there are a large number of welded studs. Moreover, tests using such methods may have individual differences depending on the person being tested, and are not absolute. For this reason, for example, in civil engineering construction, etc., a larger number of studs than the required number are welded in advance in anticipation of some degree of welding failure. This not only wastes welding power and studs, but also increases operating costs.

Therefore, the purpose of the present invention is to detect welding defects non-destructively at the same time as welding by electrically measuring the welding current, the current application time, and the timing of pushing the stud into the base metal in a capacitor discharge type stud welding machine. Therefore, according to the present invention, this welding monitor device detects the arc ( (fracture)
A measurement circuit that measures the time until the detection of the current increase rate (Δi/Δt) at the time of disappearance, a peak value detector that detects the peak value of the welding current, and a display that digitally displays the measured time, and a display that digitally displays the peak value, and
It is configured to inspect the welding condition of the stud by checking whether the peak value and the rate of current rise (Δi/Δt) are within predetermined tolerances.

The welding monitoring device according to the invention can preferably be provided with a device for performing the above checks and generating an alarm signal if each parameter is not within a predetermined tolerance range.

The present invention will be further explained below with reference to the additional drawings.

FIG. 1 shows a welding monitor device according to the present invention as a block diagram, in which 1 is a shunt circuit forming an input circuit for detecting a welding current from a welding capacitor and a gate current that causes the welding current to flow, 2 is an attenuator, and 3 is a shunt circuit. waveform shaping circuit; 4 is an amplifier circuit; 5 is a digital display for energization time consisting of a digital counter; 6 is an amplifier circuit; 7 is a peak value holding circuit; 8
9 is a peak value digital display, 9 is an energization time tolerance range setting device, 10 is a comparator, 11 is an alarm signal generator, 12 is a peak value tolerance range setting device,
13 is a comparator, and 14 is an alarm signal generator.
The gate current detected by the input circuit 1 (the current that turns on the discharge circuit of the welding capacitor, that is, the welding circuit, schematically indicated by the _{symbol I} ) is attenuated by an attenuator 2, and on the other hand is supplied to a time measuring circuit, that is, waveform-shaped by a broken waveform shaping circuit 3, amplified by an amplifier circuit 4 and supplied to a digital display 5, and is thus supplied to a gate The time from the generation of the current I _G to the detection of the current increase rate ΔI/Δt (Fig. 2) when the arc (flash) disappears is measured, memorized, and displayed. On the other hand, the output current from the attenuator 2 is supplied to the peak value holding circuit 7 via the amplifier circuit 6, and is designated by the symbol I _P in FIG.
The peak value of the welding current I _W shown by is detected, and this peak value I _P is displayed on a digital display 8 consisting of an ammeter.

The device thus constructed is configured such that the previously measured and stored data is reset by inputting the gate current I _G again.

Further, in this invention, the measured time is
A comparator 10 compares whether the measured energization time is within the allowable range set by It can be made to emit. Similarly, a comparator 13 compares whether the peak value I _P stored in the digital display 8 is within the allowable range set by the device 12, and if the peak value I _P is not within the set range, the device 11 A similar device 14 may be activated to issue an alarm.

In the waveform shown in FIG. 2, the larger the current rise rate ΔI/Δt at the time of arc extinguishment that occurs when pressing the stud against the base metal, the more reliable and better welding will be performed.

When using this device, for example, the peak current value I _P
If the measured time is within the set tolerance range and the measured time is outside the set tolerance range, the sliding or tilting of the welding gun of the welding machine is the cause, and the peak current value I _P is outside the tolerance range and the measured time is outside the set tolerance range. If it is within the allowable range, it can be determined that the cause is the charging voltage of the welding capacitor of the welding machine or a failure in the cable loop.

As explained above, according to the device according to the present invention, by measuring the peak value of welding current and its energization time, it is possible to check for welding defects on studs at the same time as welding work, and also to investigate the cause of welding defects. and countermeasures can be easily taken. Therefore, productivity can be dramatically increased, and at the same time, waste of materials such as studs can be reduced, and costs can be significantly reduced. Furthermore, when used, for example, in mass production factories for the automobile industry, home appliances, etc., it is possible to increase production efficiency and improve product quality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a welding monitor device according to the present invention, and FIG. 2 is a diagram schematically showing a welding current waveform of a capacitor discharge type stud welding machine implementing the present invention. In the figure, 1 is an input circuit, 2 is an attenuator, 3 is a waveform shaping circuit, 4 is an amplifier circuit, 5 is a digital display, 6 is an amplifier circuit, 7 is a peak value holding circuit, 8
is a digital display.

Claims (1)

[Claims] 1. Start with a gate current that causes welding current to flow from a welding capacitor of a welding machine, start time measurement, and detect the rate of increase in current (ΔI/Δt) when the stud is pressed against the base material. A welding current energization time measurement circuit that finishes time measurement at the welding current, a peak value detector that detects the peak value of the welding current, an energization time display that digitally displays the output signal of the energization time measurement circuit, and a peak value detector. It has a peak value display that digitally displays the peak value of welding current detected by
1. A welding monitor device for a capacitor discharge type stud welding machine, characterized in that it is configured to inspect welding of studs by I/Δt). 2. Welding according to claim 1, characterized in that the welding device has a device that compares the measured energization time and peak value with respective set values and generates an alarm signal when the measured energization time and peak value are outside the predetermined allowable range. Monitor device.