JPS61150784A - Method and device for displaying current conduction allowable of resistance welding machine - Google Patents

Abstract

PURPOSE:To permit the easy identification of a current conduction allowance by calculating the weld time of tip current or dip current from the waveform of welding current and displaying the conduction state of the current as the current conducting angle or current conducting allowance angle respectively. CONSTITUTION:A welding current detector 10 is provided to detect the welding current of a secondary lead wire 5 of a welding transformer. The output is obtd. in the form of the differential waveform of actual welding and is subjected to waveform conversion to the original welding current by an integrator 11, then the absolute value thereof is subjected to analog-to-digital conversion. The result thereof is digitized and inputted to a CPU14 which calculates the OR with a comparator 16. The weld time of the tip current of the welding current is calculated by the above-mentioned method, by which the current conducting angle and the current conducting allowance angle are determined. The result are displayed on a display device 17. The current conducting allowance is thus easily identified.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for displaying a welding current carrying margin in a resistance/8 welding machine.

(Prior Art and its Problems) Conventionally, methods and devices for controlling the /8 contact current to a predetermined value in a resistor/8 contact machine have been known. Then, in order to control the /8 contact current to a predetermined value, the welding current is detected,
Methods and devices for feedback controlling this are known.

(Problems to be Solved by the Invention) However, even with a device that can control the welding current to a predetermined value in a resistance welding machine, the energization state during welding is relative to the maximum current value of the resistance welding machine.

There is a problem in that it is not possible to determine whether the power is being turned on with sufficient margin or whether it is at the limit of the permissible range. That is, due to lead wire wear on the secondary side of the welding transformer of a resistance welding machine, wear and tear of the welding tip, the resistance value of the conductor to which the /8 contact current should be applied increases, and /
Even if the permissible amount of 8-contact current was reduced, the current flow margin could not be determined. Especially in welding robots, etc.
Currently, the lead wire on the secondary side of an 8-junction transformer is longer than that of conventional welding machines, so it is important to understand the reduction in current carrying margin due to lead wire wear etc. in order to know when to replace the lead wire. be.

This invention was made to solve the above-mentioned problems, and provides a method for displaying current flow margin that can improve the reliability of a resistance welding machine by understanding the current flow margin of the welding current of the resistance welding machine. and a display device.

(Means for solving the problem) In this invention, as a means for solving the above-mentioned problem, /
8. A resistance welding machine that detects a welding current at the time of contact, calculates the energization time of the tip current or dip current from the waveform of the detected welding current, and displays the energization state of the tip current or dip current. This is the method of displaying the current carrying margin.

According to another solution, there is provided a welding current detection device that detects a welding current during welding, a device that calculates the energization time of a tip current or dip current from the waveform of the welding current detected by the detection device, and a tip A device for displaying the current flow margin of a resistance welding machine is characterized in that it displays the current flow state of current or dip current.

(Example) Embodiments of the invention will be described based on the drawings.

FIG. 1 is a block diagram showing an embodiment applied to a method and display device for displaying current flow margin of a resistance welding machine, and FIG. 2 is a diagram showing waveforms of various parts of the embodiment.

First, to explain the configuration of Fig. 1, 1 is a welding tip (welding electrode) for welding, 2 is a material to be welded, 3 is a welding transformer, 4.5 is a secondary lead wire of the welding transformer, and 6 is a welding tip for welding. , 7 are secondary lead wires of the welding transformer, and show an outline of the resistance welding machine. 10 is a current transformer (welding current detection device) for detecting welding current;
The secondary side of the f6 transformer consists of a toroidal coil.

Detects welding current from the lead wire. In Figure 2,
(a) is the waveform of the welding current actually flowing through the lead wire, 20 is the tip current which serves as a heat source for welding the welder knob, and the energization period of the tip current 20 is the energization angle. It is A. 21 is a dip current, which is a current between the tip current 20 and does not serve as a heat source for the welding tip.

The energization period of the dip current is the energization margin angle, which indicates the energization margin of the welding machine. (b) in FIG. 2 is a detected waveform of the welding current detected by the current transformer 10,
It appears as a differential waveform of the actual welding current. Next, we will describe the configuration for measuring the energization period of the tip current or dip current of the welding current from the detected welding waveform and displaying the energization state. ．． Analog/Digital (A-D
) is connected to the CPU 14 via the converter 13, and
It has a configuration in which it is connected to the CPU 14 via an absolute value circuit 15 and a comparator 16. and.

The CPU 14 calculates the energization state of the welding current, and the result is displayed on the display W'17.

Next, the effect will be explained. First, the current transformer 10 detects the welding current during welding. As explained above, the detected current waveform (FIG. 2(b)) is output as a differential waveform of the actual welding current (FIG. 2(a)). Therefore, the differential waveform is integrated by an integrator 11 to convert the waveform into the original welding current as shown in FIG. 2(c). Next, the absolute value of the current waveform converted to the original welding current is converted to the absolute value circuit 1.
2 as shown in FIG. 2(d), and the Δ-reverse converter 13
D-convert. A-D conversion is 1/2 of /8 contact current
There are 64 samplings per Hz. and,
The digitally converted welding current waveform (Fig. 2e) is converted into CP
Input to U14.

Further, the absolute value of the welding current detected by the current transformer 10 is taken by an absolute value circuit 15 as shown in FIG. 2(f),
Comparing the absolute value waveform at a predetermined reference level, FIG. 2(g)
(digitize and input to CPLJ14).

In the CPUI 4, the output waveform of the A-D converter 13 (second
The logical OR of the output waveform of the comparator 16 (FIG. 2(g)) is calculated. The logical sum of both is A-D.
This is to determine the energization state of the welding current based on the output of the converter 13, and to grasp the rising timing and falling timing of the welding current based on the output of the comparator 16. Then, the energization timing of the tip current of the welding current is calculated. The energization timing is shown as the time between 1/2 cycles of the welding current.

Next, the energization time of this 1,000-knob current is converted into an angle, that is, a energization angle. Since the 1/2 period of the welding current is 180°, the energization margin angle (dip current energization period) can be found by subtracting 1ffl electrical angle from 180°. By displaying this result on the display device 17, the energization margin angle, which is the energization margin of the /8 contact current, is displayed.

That is, according to this embodiment, the energization period of the tip current of 1/2 cycle of the welding current is determined, and this is converted into the energization angle, and the 9 energization margin angle can be determined and displayed, so that the maximum permissible amount of the resistance welding machine can be determined. against.

It is easy to judge how much margin there is for the current to be applied. Furthermore, the wear condition of the secondary side wire of the welding transformer can be easily determined, and the reliability of the resistance welding machine can be improved.

In the above-described embodiment, the tip current of the welding current is converted into a conduction angle, and the conduction margin is determined and displayed from one conduction angle, but it is also possible to display one conduction angle as is. The current flow margin can be easily determined based on the current flow angle.

Alternatively, the energization time of the dip current may be determined, and the energization margin angle may be displayed as it is by converting the angle.

Detection of the welding current is not limited to a current transformer, but may also use a shunt resistor, Hall element, etc. Also, the detection position of the /8 contact current is not limited to the secondary side of the welding transformer, but may also be on the primary side. It's okay.

The mode of the display device may be a printer display, an LED display, or the like.

(Effects of the Invention) According to the present invention, the welding current flow margin of a resistance welding machine can be easily grasped, and the reliability of the resistance welding machine can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 is a diagram showing waveforms of various parts in the same embodiment. (Explanation of symbols) 10...Current transformer 11...Integrator 12.15...Absolute value circuit 13...A-D converter 14...CPU 16...Comparator 17...・Display device 20...Chip current 21...Dip current A...Conducting angle B...Conducting margin angle

Claims (6)

[Claims] (1) A method of displaying the energization margin of a resistance welding machine, comprising:
A resistance welding machine that detects a welding current during welding, calculates the energization time of the tip current or dip current from the waveform of the detected welding current, and displays the energization state of the tip current or dip current. How to display the current carrying margin. (2) A method for displaying current flow margin of a resistance welding machine as set forth in claim 1, wherein the current flow state of the tip current is displayed as a flow angle of the welding current. (3) A method for displaying the energization margin of a resistance welding machine as set forth in claim 1, wherein the energization state of the dip current is displayed as a energization margin angle of the resistance welding machine. (4) A device that displays the energization margin of a resistance welding machine,
a welding current detection device that detects a welding current during welding; a device that calculates the energization time of a tip current or dip current from the waveform of the welding current detected by the detection device;
1. A display device for indicating current flow margin of a resistance welding machine, comprising a device for displaying a current flow state of a tip current or a dip current. (5) In the description of claim 4, the device for displaying the energization state of the tip current is a device that displays the energization state of the tip current as a current flow margin angle of the welding current. Ample display device. (6) The device for displaying the energization margin of a resistance welding machine according to claim 4, wherein the device that displays the energization state of the dip current is a device that displays the energization margin angle of the dip current.