JP2000225473A - Device for monitoring resistance welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exactly find the propriety of welding conditions even when the welding conditions are changed by taking a set numerical value as the numerical value which is arbitrarily selected from calculated numerical value when the propriety of a detected value is decided by detecting a voltage between electrodes or welding current during energizing and comparing with a set numerical value. SOLUTION: The welding current and welding voltage are detected in a detecting part 6 and the number of weldings are counted in a counter part 7. Numerical analysis and operation are executed by the data of the detecting part 6 and counter part 7 in an arithmetic part 8. The measured value of the detecting part 6 is compared with the calculated numerical value of the arithmetic part 8 in a comparing part 11. The reference nugget diameter is calculated from the calculated numerical value in a reference value arithmetic part 10. The reference nugget diameter is compared with an estimated nugget diameter which is estimated with an estimated value arithmetic part 9 in a nugget diameter comparing part 12. On the basis of the calculated result (the average value of arbitrary number of weldings, the moving average value of arbitrary plural number including the detected value just before being detected) calculated with the arithmetic part 8, the reference value is calculated in the reference value arithmetic part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding monitoring apparatus for resistance welding, particularly spot welding.

[0002]

2. Description of the Related Art Conventional welding quality monitoring devices include the following welding quality monitoring devices for notifying maintenance timing such as replacement or repair of a welding tip at a welding site.

Hereinafter, description will be made with reference to FIG. In FIG. 4, reference numeral 26 denotes a detecting unit for detecting a welding current and a welding voltage, which is measured by integrating a welding current signal detected using a toroidal coil 25 attached to the electrode 21, and a voltage between the electrodes 21. , 22 are measured using the voltage detection line 24 attached thereto. Numeral 27 is a numerical calculation simulator for numerically calculating the temperature distribution based on the heat conduction model in response to the measurement result of the detection unit 26, and estimates the temperature distribution of the workpiece 23 and the welding electrodes 21 and 22 for each unit time. This is a calculation unit for estimating a nugget diameter (hereinafter referred to as an estimated nugget diameter) generated by distribution. As for the numerical simulation simulator, a numerical calculation simulator that uses the measured welding current and welding voltage to numerically calculate the temperature distribution and the conduction diameter based on the heat conduction model is described in “Resistance Welding Research Committee of the Japan Welding Society: Resistance Welding Research Committee”. Phenomena and Their Applications (1) ", Welding Society of Japan (Showa 57), pp. 12-52.

[0004] Reference numeral 28 denotes a nugget diameter setting unit for setting a set value of a reference nugget diameter (hereinafter referred to as a set nugget diameter) in advance, and 29 denotes an estimated nugget diameter calculated by the calculation unit 27 and input to the nugget diameter setting unit 28. The nugget diameter comparison unit calculates the time at which the estimated nugget diameter exceeds the set nugget diameter (hereinafter, estimated formation time) by comparing the estimated nugget diameter with the set nugget diameter. Reference numeral 30 denotes a formation time setting unit for setting a reference formation time (hereinafter referred to as “set formation time”) in advance, and 31 denotes an estimated formation time calculated by the nugget diameter comparison unit 29 and a set formation time input to the formation time setting unit 30. And 32 is an output unit that outputs the comparison result of the formation time comparison unit 31.

[0005] In the above configuration, an estimating nugget diameter is calculated by a numerical calculation simulator in a calculating unit 27 based on the welding current and welding voltage detected by the detecting unit 26, and the estimated nugget diameter is calculated by a nugget diameter comparing unit 29. The estimated formation time is calculated by comparing with the set nugget diameter. Further, the estimated formation time is compared with the set formation time by the formation time comparison unit 31, and the result is output.

[0006]

In the conventional resistance welding monitoring apparatus, the time at which the nugget is formed is gradually delayed by the wear of the electrode due to an increase in the number of hit points (the number of weldings). Estimation is performed by the above-described configuration using the conduction model, and this is compared with a reference set forming time, so that a maintenance time such as resetting of welding conditions or replacement and repair of a welding tip can be notified.

However, in the above-described conventional resistance welding monitoring apparatus, since the estimated forming time is determined to be good or bad with respect to the initially set forming time, when the welding conditions such as a change in the welding current are changed, the welding conditions are changed. There was a problem that the propriety could not be notified accurately.

SUMMARY OF THE INVENTION An object of the present invention is to provide a resistance welding monitoring apparatus capable of accurately informing whether welding conditions are appropriate even when welding conditions are changed.

[0009]

According to a first aspect of the present invention, there is provided a resistance welding monitoring apparatus for detecting whether or not a detected value is appropriate by detecting a voltage between electrodes or a welding current during energization and comparing the detected value with a set value. The setting numerical value is characterized by using an arbitrarily selected operation numerical value.

[0010] According to the resistance welding monitoring device of the first aspect, the set numerical value is an arbitrarily selected operation numerical value, and the detected value is compared with the set numerical value, so that even if the welding conditions are changed, it can be accurately performed. It is possible to notify whether welding conditions are appropriate.

According to a second aspect of the present invention, there is provided a resistance welding monitoring apparatus for detecting whether or not a detected value is appropriate by detecting a voltage between electrodes or a welding current during energization and comparing the detected value with a set value. It is characterized in that an average value of any number of weldings is used.

[0012] According to the resistance welding monitoring apparatus of the second aspect, the set value is an average value of an arbitrary number of times of welding, and the detected value is compared with the set value, so that even when the welding conditions are changed, it can be accurately performed. It is possible to notify whether welding conditions are appropriate.

According to a third aspect of the present invention, there is provided a resistance welding monitoring apparatus for detecting whether or not a detected value is appropriate by detecting a voltage between electrodes or a welding current during energization and comparing the detected value with a set value. It is characterized by using an arbitrary plural number of moving average values including a detected value immediately before a detected numerical value.

According to the resistance welding monitoring apparatus of the third aspect, the set numerical value is a moving average value of a plurality of times including the detected value immediately before the detected numerical value, and the detected value is compared with the set numerical value. Even if the welding conditions are changed, the appropriateness of the welding conditions can be notified accurately.

According to a fourth aspect of the present invention, a resistance welding monitoring apparatus detects a voltage between electrodes and a welding current during energization, calculates a nugget diameter inside a material to be welded by a numerical calculation simulator, and compares the nugget diameter with a reference nugget diameter. An apparatus for judging whether welding quality is appropriate or not, wherein the reference nugget diameter uses an arbitrarily selected operation value.

According to the resistance welding monitoring apparatus of the fourth aspect, the reference nugget diameter is an arbitrarily selected operation value,
By comparing the nugget diameter calculated by the numerical calculation simulator with the reference nugget diameter, even if the welding conditions are changed, it is possible to accurately notify the welding conditions whether or not the welding conditions are appropriate.

According to a fifth aspect of the present invention, a resistance welding monitoring apparatus detects a voltage between electrodes and a welding current during energization, calculates a nugget diameter inside a material to be welded by a numerical calculation simulator, and compares the nugget diameter with a reference nugget diameter. An apparatus for judging whether welding quality is appropriate or not, wherein the reference nugget diameter uses a value calculated by at least one of the set numerical values obtained in claim 1, claim 2, or claim 3. It is assumed that.

According to a fifth aspect of the present invention, the reference nugget diameter is a value calculated by at least one of the set values obtained in the first, second, or third aspects. By comparing the nugget diameter calculated by the calculation simulator with the reference nugget diameter, even if the welding conditions are changed, it is possible to accurately notify whether or not the welding conditions are appropriate.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram showing the configuration of the resistance welding monitoring device. In FIG. 1, reference numeral 6 denotes a detection unit for detecting a welding current and a welding voltage, which is measured by integrating a welding current signal detected using a toroidal coil 5 attached to the electrode 1, and a voltage between the electrodes 1 , 2 are measured using the voltage detection line 4 attached to the power supply. Numeral 9 is a numerical calculation simulator for numerically calculating the temperature distribution based on the heat conduction model based on the measurement result of the detection unit 6, and estimates the temperature distribution of the workpiece 3 and the welding electrodes 1 and 2 per unit time,
This is an estimated value calculation unit for estimating an estimated nugget diameter generated based on a temperature distribution. Reference numeral 7 denotes a counter unit for counting the number of weldings. Reference numeral 8 performs a numerical analysis based on the measurement result of the detecting unit 6, and performs a process of calculating the number of weldings counted by the counter unit 7. Reference numeral 11 denotes a comparison unit that compares the measurement result of the detection unit 6 with the calculation numerical result calculated by the calculation unit 8. Reference numeral 10 denotes a reference value calculation unit that calculates a reference nugget diameter from the calculation numerical result calculated by the calculation unit 8. Reference numeral 12 denotes an estimated nugget diameter estimated by the estimation value calculation unit 9 and a reference value calculation unit 10. It is a nugget diameter comparison unit that compares the calculated reference nugget diameter. Reference numeral 13 denotes an output unit that outputs the result of comparison by the comparison unit 11 and the result of comparison by the nugget diameter comparison unit 12.

FIG. 2 is a diagram showing the relationship between the number of hit points and the current value measured by the detector 6 and the result of the numerical value calculated by the calculator 8. In FIG. 2, the current value indicates an average effective current value during the energization time. From FIG. 2, when the current value is changed in accordance with the increase in the number of hit points, it is possible to accurately judge whether the welding conditions are appropriate even if any condition is changed by using the calculated value as the set value which is the criterion. I understand.

It is to be noted that changing the current value with the increase in the number of hit points means that the current mainstream of resistance welding is welding by a constant current control device. During this period, control is performed so that a set current value (effective current value) flows. At the actual welding site, the electrode wears with the increase in the number of spots, so when welding reaches the set number of spots, it is set so that welding is performed with a current value increased by several percent from the initial set current value. Have been. For example,
First set 10kA, 5% increase after 100 RBIs,
It is set to increase by 10% after 200 hit points.

The above calculated numerical value indicates an average value of an arbitrary number of weldings, and the average value of an arbitrary number of weldings is as follows.
This is a value obtained by averaging the detection values in the number of hit points set by the user and multiplying by the numerical value set by the user.

Further, any of the above-mentioned condition changes includes a change in a welding current value, a pressurizing force, an energizing time, and the like.

In addition to the case where the calculation result for the number of weldings is used as shown in FIG. 2, the set numerical value may be any number of times including an arbitrarily selected calculated value and a detection value immediately before the detected value. A moving average value may be used. Note that the arbitrarily selected calculated value is a result of the user setting a rate of increase of the determination criterion with respect to the number of hit points and calculating the set value, and a value immediately before the detected value. The moving average value of a plurality of times including the detection value of the above means that the moving average value of the detected current value (measured value) is used as a criterion. In this manner, the set value is compared with the set value as an arbitrarily selected operation result or as a moving average value of a plurality of times including the detected value immediately before the detected value. As a result, it is possible to accurately notify the welding conditions.

The detected value may be a voltage value.

FIG. 3 is a diagram showing the relationship between the estimated nugget diameter calculated by the estimated value calculator 9 and the reference nugget diameter calculated by the reference value calculator 10 with respect to the number of hit points. From FIG. 3, since the electrode tip is worn and the energized area increases with an increase in the number of hit points, the estimated nugget diameter increases accordingly, and the calculation result obtained by arbitrarily selecting a reference nugget diameter as a criterion is used. It can be seen that the welding conditions can be accurately determined. The arbitrarily selected calculation result is defined as a reference nugget which is a determination criterion when the user sets a ratio of the reference nugget diameter to the estimated nugget diameter, and thereby the estimated nugget diameter increases. The diameter will also increase automatically. In this way, it refers to the calculation result calculated for the value arbitrarily selected by the user.

When calculating the reference nugget diameter in the reference value calculating section 10, the calculation results calculated in the calculating section 8 (arbitrarily selected calculated values, calculated numerical values which are average values of an arbitrary number of weldings). , A moving average value of any number of times including the detected value immediately before the detected numerical value), and comparing the nugget diameter with the reference nugget diameter to accurately notify whether welding conditions are appropriate or not. Can be. Note that the calculation result calculated by the calculation unit 8 is to calculate a reference nugget diameter with respect to the calculated current value as a criterion, and the same applies to the voltage value. May be calculated for both. For example, y = x + a (y: reference nugget diameter,
It is calculated by an arithmetic expression such as x: current value (voltage value), a: constant.

[0029]

According to the resistance welding monitoring apparatus of the first aspect, the set value is an arbitrarily selected operation value, and the detected value is compared with the set value, so that even if the welding conditions are changed, the appropriate value can be obtained. It is possible to accurately notify the welding conditions.

According to the resistance welding monitoring device of the present invention, the set value is set to an average value of an arbitrary number of times of welding, and the detected value is compared with the set value, so that even if the welding conditions are changed, it can be accurately performed. It is possible to notify whether welding conditions are appropriate.

According to the resistance welding monitoring apparatus of the third aspect, the set numerical value is a moving average value of a plurality of times including the detected value immediately before the detected numerical value, and the detected value is compared with the set numerical value. Even if the welding conditions are changed, the appropriateness of the welding conditions can be notified accurately.

According to the resistance welding monitoring device of the fourth aspect, the reference nugget diameter is an arbitrarily selected operation value,
By comparing the nugget diameter calculated by the numerical calculation simulator with the reference nugget diameter, even if the welding conditions are changed, it is possible to accurately notify the welding conditions whether or not the welding conditions are appropriate.

According to the resistance welding monitoring apparatus of the fifth aspect, the reference nugget diameter is a value calculated by at least one of the set values obtained in the first, second and third aspects. By comparing the nugget diameter calculated by the calculation simulator with the reference nugget diameter, even if the welding conditions are changed, it is possible to accurately notify whether or not the welding conditions are appropriate.

[Brief description of the drawings]

FIG. 1 is a block diagram of a resistance welding monitoring device according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a detected current and a calculated value with respect to the number of hit points of the resistance welding monitoring apparatus according to one embodiment of the present invention.

FIG. 3 is a graph showing a relationship between an estimated nugget diameter and a reference nugget diameter with respect to the number of hit points of the resistance welding monitoring apparatus according to one embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional resistance welding quality monitoring device.

[Explanation of symbols]

 1, 2 electrode 3 work piece 4 voltage detection wire 5 toroidal coil

Claims (5)

[Claims] 1. A resistance welding monitoring apparatus for detecting whether or not a detected value is appropriate by detecting a voltage between electrodes or a welding current during energization and comparing the detected value with a set value, wherein the set value is arbitrarily selected. A resistance welding monitoring device characterized by using a calculated value. 2. A resistance welding monitoring device which detects whether or not a detected value is appropriate by detecting a voltage between electrodes or a welding current during energization and comparing the detected value with a set value. A resistance welding monitoring device using an average value. 3. A resistance welding monitoring device which detects whether or not a detected value is appropriate by detecting a voltage between electrodes or a welding current during energization, and comparing the detected value with a set value. A resistance welding monitoring device characterized by using a moving average value of a plurality of times including an immediately preceding detection value. 4. A resistor for judging whether welding quality is proper or not by detecting a voltage between electrodes and a welding current during energization, calculating a nugget diameter inside a material to be welded by a numerical calculation simulator, and comparing the nugget diameter with a reference nugget diameter. An apparatus for monitoring resistance welding, wherein the reference nugget diameter uses an arithmetic value arbitrarily selected. 5. A resistance for detecting whether welding quality is appropriate by detecting a voltage between electrodes and a welding current during energization, calculating a nugget diameter inside a material to be welded by a numerical calculation simulator, and comparing the nugget diameter with a reference nugget diameter. 4. A resistance monitoring apparatus according to claim 1, wherein said reference nugget diameter uses a value calculated by at least one of the set values obtained in claim 1, claim 2, or claim 3. apparatus.