JPH05337657A - Resistance welding controller - Google Patents

Abstract

PURPOSE:To provide the resistance welding controller capable of reducing the generation of expulsion and surface flash due to excessive input and the generation of the shortage of the nugget diameter due to electrode damage and too little input. CONSTITUTION:A detection part 1 detects at least one physical quantity on a part to be welded and an arithmetic part 3 carries out numerical analysis of the energizing diameter or the energizing diameter and the nugget diameter by using this physical quantity. A comparison part 2 outputs the result obtained by comparing the physical quantity with a model waveform as a control signal or outputs the result obtained by comparing the model wave form of the nugget diameter with the nugget diameter estimated by the arithmetic part 3 as a control signal. An output command part 4 controls a power source part 5 with heat input density pert the energizing diameter as a reference by using the energizing diameter output from the arithmetic part 3 and the control signal outputted by the comparison part 2 and changes at least one of a welding current, the welding time and the welding force. Accordingly, heat input density control not effected by the size of the energizing diameter can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of a resistance welding control device during welding.

[0002]

2. Description of the Related Art As a measure for improving the quality of resistance welding, the physical quantities of welding current and interelectrode resistance are detected and compared with the set model waveform, or there is a correlation between the physical quantity and the nugget diameter. Therefore, it is common to control resistance welding.

FIG. 4 shows an example of the output state of the resistance welding machine by the control method using the interelectrode resistance as the physical quantity. Figure 4
In t, t1 and t2 indicate times at which the measured inter-electrode resistance value starts to separate from the model waveform. Also, Δp1 and Δp2
Indicates the output adjustment width for bringing the detected waveform closer to the model waveform. In the conventional control, the output command value is controlled as follows according to the magnitude relationship between the interelectrode resistance and the model waveform.

As shown in FIG. 4A, when "the detected waveform of a certain physical quantity is larger than the model waveform", the output command value is Δp1 so that the physical quantity approaches the model waveform.
It only lowers the heat input to the nugget part.

Further, as shown in FIG. 4B, when the detected waveform of a certain physical quantity is smaller than the model waveform, the output command value is increased by Δp2 so that the physical quantity approaches the model waveform. Increase heat input to the section.

In any case, Δp1 and Δp2
Has a value unrelated to the physical phenomenon of nugget formation. In order to solve this problem, a numerical calculation simulator was developed to measure the welding current and welding voltage, numerically calculate the temperature distribution and energization diameter based on the heat conduction model, and estimate the nugget diameter. The simulator is effective in estimating the welding state and the diameter of the generated nugget, but it did not have the function of positively improving the welding results. (Reference: Edited by Resistance Welding Research Committee of Japan Welding Society)
"Resistance Welding Phenomenon and Its Applications (1)", Japan Welding Society, (Showa 57), pp. 12-52)

[0007]

As described above, the conventional control is to detect the difference between the physical quantity and the model waveform and increase or decrease the output command value by a constant value. No consideration was given to the change in the heat input density to the nugget portion due to the change in the current-carrying diameter, which is a major factor in welding. Therefore, when the amount of output change is constant, the heat input density becomes excessive in the initial stage of energization, where the energization diameter is relatively small, and dust and electrode damage occur due to rapid nugget growth. In the latter half, the heat input density becomes too small,
I didn't get the necessary nugget growth. Also, when a galvanized steel plate is used for the work, the energizing diameter tends to expand with time, so if the output change is constant, it is difficult to control the heat input corresponding to the rapidly enlarging energizing diameter. there were.

The present invention controls the heat input to the nugget portion,
An object of the present invention is to provide a resistance welding control device capable of reducing the occurrence of dust due to excessive input, electrode damage, and the occurrence of insufficient nugget diameter due to excessive input.

[0009]

In order to achieve the above object, a first resistance welding control apparatus of the present invention comprises a welding current applied between welding electrodes sandwiching a material to be welded, an interelectrode voltage, a welding electrode. A detector for detecting at least one physical quantity of displacement, electrode pressure, welding electrode temperature, or welded part temperature, and a numerical value for numerically analyzing an energization diameter based on a heat conduction model using the physical quantity detected by the detector. A calculation unit having a calculation simulator, a comparison unit for outputting the result of comparison between the physical quantity detected by the detection unit and the set model waveform as a control signal, and the energization diameter output numerically analyzed by the calculation unit and the comparison Using a control signal output from the welding unit, an output command unit that controls the welding machine output based on the heat input density per energized diameter and an output command value output from the output command unit Current, characterized in that a power supply section for changing at least one of the welding time or pressure.

The second resistance welding control system of the present invention is a welding current applied between welding electrodes sandwiching a material to be welded,
A detection unit for detecting at least one physical quantity of an inter-electrode voltage, a displacement of a welding electrode, an electrode pressing force, a welding electrode temperature or a welded portion temperature, and a heat conduction model based on the physical quantity detected by the detection unit The result of comparing the nugget diameter estimated by the calculation unit with a numerical calculation simulator that estimates the nugget diameter from this temperature distribution and the numerical analysis of the temperature distribution and the energized diameter, and the nugget diameter estimated by the calculation unit. Control unit controls the welding machine output based on the heat input density per energizing diameter by using the comparing unit that outputs as a control signal, the energizing diameter output numerically analyzed by the computing unit, and the control signal output by the comparing unit. And an electric power source unit that changes at least one of welding current, welding time, and pressure force according to the output command value output from the output command unit. And wherein the digit.

[0011]

According to this structure, it is possible to control the heat input density without being affected by the size of the energizing diameter, suppress the occurrence of dust, the damage to the electrode or the shortage of the nugget diameter, and improve the resistance welding quality. In addition, control can be applied to welding of galvanized steel sheets.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The resistance welding control device of the present invention will be described below with reference to the embodiments shown in FIGS.

The resistance welding control apparatus of the present invention is constructed as shown in FIG. Power is supplied from the power supply unit 5 via the welding electrodes 6 and 7 with the work 8 sandwiched therebetween. The detection unit 1 detects at least one physical quantity of the welding current I, the inter-electrode voltage V, the inter-electrode displacement Δg, the electrode pressing force P, the electrode temperature T1 or the welded part temperature T2. The model waveform of each physical quantity input from the detection unit 1 is stored in the comparison unit 2 in advance, and the control signal can be increased or decreased by comparing with the input. A numerical analysis method of the energization diameter by the numerical calculation simulator configured in steps # 1 to # 8 shown in FIG. 2 is set in the calculation unit 3, and by inputting the physical quantity detected by the detection unit 1, The current-carrying diameter can be obtained by numerical analysis. In this calculation unit 3, the welding current, the voltage between the electrodes,
Numerical analysis of the current-carrying diameter can be performed by using any one of the physical quantities of displacement between electrodes, electrode pressure, electrode temperature or welded part temperature as input data, but the accuracy of analysis results improves as the number of input physical quantities increases. Can be expected.

The output command unit 4 outputs to the power supply unit 5 according to the control signal from the comparison unit 2, the result of comparison of the energizing diameter output from the calculation unit 3 and the welding start condition and welding end condition stored inside. Output a command signal. The power supply unit 5 is configured to change at least one of welding current, welding time and pressure based on the output command signal.

Next, referring to the explanatory view shown in FIG. 3, FIG.
The configuration will be described in more detail. In response to a start signal from the outside, the output command unit 4 outputs to the power supply unit 5 an output command signal based on the arbitrarily set start condition. Upon receiving the output command signal from the output command unit 4, the power supply unit 5 starts energization,
At any time, the detection unit 1 displays the welding current, the inter-electrode voltage,
Detects some or all of electrode displacement, electrode pressure, electrode temperature or welded part temperature. Part or all of the detected physical quantity is input to the comparison unit 2 and the calculation unit 3. The comparison unit 2 compares the detected value of the physical quantity input from the detection unit 1 with the model waveform of the physical quantity stored in advance in the comparison unit 2, and increases or decreases the control signal as follows as shown in FIG. ..

As shown in FIG. 3 (a), when the detected waveform of a certain physical quantity is larger than the model waveform, in order to bring the physical quantity closer to the model waveform, the output command value is decreased or terminated, The control signal is lowered or terminated by Δs1. As shown in FIG. 3B, when the detected waveform of a certain physical quantity is smaller than the model waveform, the control signal is increased by Δs2 in order to increase the output command value in order to bring the physical quantity closer to the model waveform. increase.

Further, the calculation unit 3 optionally uses a part or all of the welding current, the inter-electrode voltage, the inter-electrode displacement, the electrode pressing force, the electrode temperature or the welded part temperature detected by the detecting unit 1. Numerical analysis of the energizing diameter at the time of
Output to the output command unit 4. The output command unit 4 controls the output by increasing or decreasing the output command signal to the power supply unit 5 as shown in FIG. 3 and the following, depending on the result of comparison between the control signal and the numerically analyzed energizing diameter or the welding end condition. Or end it.

When the current-carrying diameter is large and the output is constant, the heat input to the current-carrying diameter is too small, and the probability of occurrence of a nugget shortage due to a decrease in nugget growth increases. The output command value is increased by Δd1 from the standard value D ₁ at that time, and the heat input to the nugget portion is increased to make the heat input density within the energized diameter constant.

When the current-carrying diameter is small and the output is constant, the heat input to the current-carrying diameter becomes excessive, and the probability of dust generation due to rapid nugget growth increases, so that the control signal is suitable for the input. The output command value is reduced by Δd2 from the standard value D ₂ at that time, and the heat input to the nugget portion is reduced to make the heat input density within the energized diameter constant.

As described above, according to the embodiment of the present invention, it is possible to increase or decrease the output command value at any time by the energization diameter numerically analyzed. By controlling the heat input to the nugget portion, it is possible to reduce the occurrence of dust due to excessive input, electrode damage and the occurrence of insufficient nugget diameter due to excessive input.

In the above embodiment, the control signal supplied from the comparison unit 2 to the output command unit 4 outputs the result of comparing the physical quantity detected by the detection unit 1 with the set model waveform. 3 is configured by a numerical calculation simulator that numerically analyzes the temperature distribution and the current-carrying diameter based on the heat conduction model using the physical quantity detected by the detection unit 1, and estimates the nugget diameter from the temperature distribution. The same applies to the case where 2 is configured to output the result of comparing the model waveform of the nugget diameter with the nugget diameter estimated by the calculation unit 3 as a control signal.

In each of the above embodiments, the comparison unit 2 compares the physical quantity detected by the detection unit 1 with the set model waveform or the model waveform of the nugget diameter and the nugget diameter estimated by the calculation unit 3. Is configured to be output as a control signal, but not only the result of comparing the physical quantity detected by the detection unit 1 with the set model waveform, but also the model waveform of the nugget diameter and the estimation by the calculation unit 3 It is also possible to determine the control signal to be supplied to the output command unit 4 by comprehensive evaluation with the result of comparison with the nugget diameter.

In the description of the comparison unit 2 in the above embodiment, the detected value of one physical quantity input from the detection unit 1 based on FIG. 3 and the model waveform of one physical quantity stored in advance in this comparison unit 2 are described. When the control signal is increased or decreased by comparing with, but when the control signal is increased or decreased by using a plurality of physical quantities output from the detection unit 1 as an input signal, each physical quantity is compared with the model waveform of the physical quantity for each comparison. It is configured to obtain a result, comprehensively evaluate each comparison result, and determine the increase / decrease and the amount of the control signal to be output.

[0024]

According to the present invention, at least one of the welding current, the welding time and the pressing force is controlled by using the energization diameter obtained by the numerical analysis to control the heat input density to the nugget portion. By doing so, it is possible not only to reduce the occurrence of dust during welding, electrode damage and the occurrence of insufficient nugget diameter, but also to use a resistance welding machine that can adapt output control to galvanized steel sheets at low cost. Can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a resistance welding control device of the present invention.

FIG. 2 is a flow chart diagram showing a numerical analysis method of an energization diameter of a calculation unit of the embodiment.

FIG. 3 is an explanatory diagram of an output state of a comparison unit of the embodiment.

FIG. 4 is an explanatory diagram of an output state of a conventional resistance welding machine.

[Explanation of symbols]

 1 Detection part 2 Comparison part 3 Calculation part 4 Output command part 5 Power supply part 6,7 Welding electrode 8 Work [Workpiece to be welded]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Ihara 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A welding current applied between welding electrodes sandwiching a material to be welded, a voltage between electrodes, a displacement of a welding electrode, an electrode pressing force,
A detection unit that detects at least one physical quantity of the welding electrode temperature or the temperature of the welded portion, and a calculation unit that has a numerical calculation simulator that numerically analyzes the current-carrying diameter based on a heat conduction model using the physical quantity detected by the detection unit. And a comparison unit that outputs the result of comparing the physical quantity detected by the detection unit and the set model waveform as a control signal, and the energization diameter output numerically analyzed by the calculation unit and the control output by the comparison unit. At least one of a welding current, a welding time, and a pressing force depending on an output command value that controls the welding machine output based on the heat input density per energizing diameter using a signal and the output command value output from the output command part. A resistance welding control device provided with a power supply unit for changing the. 2. A welding current applied between welding electrodes sandwiching a material to be welded, a voltage between electrodes, a displacement of a welding electrode, an electrode pressing force,
The temperature distribution and the current-carrying diameter are numerically analyzed based on a heat conduction model using a detection unit that detects at least one physical quantity of the welding electrode temperature or the temperature of the welded portion, and this temperature. An arithmetic unit having a numerical calculation simulator for estimating the nugget diameter from the distribution, a comparison unit for outputting the result of comparing the model waveform of the nugget diameter and the nugget diameter estimated by the arithmetic unit as a control signal, and the arithmetic unit Using the energizing diameter output numerically analyzed by and the control signal output by the comparison unit,
An output command section for controlling the welding machine output based on the heat input density per energizing diameter, and a power supply section for changing at least one of welding current, welding time or pressure according to the output command value output from the output command section. Resistance welding control device provided with.