JP7519939B2 - Intermittent seam welding measuring device and intermittent seam welding measuring method - Google Patents

Description

The present invention relates to an intermittent seam welding measurement device and an intermittent seam welding measurement method.

Intermittent seam welding is a welding method that repeatedly cycles between passing current through a rotating electrode and resting when no current is passed. The welding time is about 1 to 5 cycles (e.g., 3 cycles) or 5 to 200 ms, and the rest time is about 1 to 3 cycles (e.g., 1 cycle) or 5 to 60 ms. The repetition time can last for several minutes.

Conventional measuring devices measure the current value of the welding circuit (hereinafter referred to as the welding current value) and the voltage value between the rotating electrodes in the welding range (hereinafter the welding current value and the voltage value between the rotating electrodes are collectively referred to as the welding current value, etc.). In this case, since the welding current value, etc. is measured without specifying each section of the current flow period and the rest period, after measuring the welding current value, etc. in the welding range, the welding current value, etc. is measured for the first 0.5 cycles or 1 ms in the section where no current is applied, and the time at which it is determined that current application has ended is measured to determine the end of measurement.

Furthermore, the effective value, arithmetic mean effective value, and peak value of the welding current value, etc. are calculated from the measured values of the welding current value, etc. The arithmetic mean effective value is obtained by calculating the effective value of the welding current value in units of 0.5 cycles or 1 ms, and averaging the results over the welding range. It is then confirmed whether the obtained effective value, arithmetic mean effective value, and peak value of the welding current value are within the judgment range, and a judgment is output.

Patent No. 5305172

The total time taken to determine that the current has ended, the time taken to calculate the effective value of the welding current, etc., and the judgment output time may be longer than the pause time. In this case, it may not be possible to measure the welding current value for the next weld.

In addition, since a judgment output is made for each measurement, it is not possible to obtain judgment results for the entire intermittent seam welding.

One aspect of the present invention provides a seam welding measuring device that includes a measurement setting unit, a current trigger circuit, a measurement circuit, a calculation processing unit, and a judgment output unit. The measurement setting unit sets a measurement time and a measurement pause time that are the same as the welding time and the welding pause time set in the intermittent seam welding device when welding a welding object by repeating a welding time during which a welding current flows through the welding object and a welding pause time during which no welding current flows. The current trigger circuit detects the current value of the welding current and obtains a welding measurement start trigger. The measurement circuit measures the current value of the welding current from the time of the welding measurement start trigger obtained by the current trigger circuit until the measurement time set by the measurement setting unit has elapsed. The calculation processing unit performs calculation processing of the measured value measured by the measurement circuit from the time after the measurement time has elapsed until the measurement pause time has elapsed. The judgment output unit judges the welding state of the welding object based on the calculation value obtained by the calculation processing unit.

The measurement setting unit sets a measurement time and a measurement pause time that are the same as the welding time and the welding pause time set in the intermittent seam welding device when welding an object to be welded by repeating a welding time during which a welding current is applied to the object to be welded and a welding pause time during which no welding current is applied to the object to be welded. The measurement circuit measures the current value of the welding current from the time of the welding measurement start trigger until the measurement time set in the measurement setting unit has elapsed. The calculation processing unit performs calculation processing of the measurement value from the time after the measurement time has elapsed until the measurement pause time has elapsed. In other words, since the measurement value is calculated within the preset measurement pause time, the entire weld can be measured and calculated. Therefore, it is possible to judge the measurement values of individual welding current values, etc., and further to judge the measurement value of the overall welding current value, etc.

According to one aspect of the present invention, the welding current value of the entire intermittent seam welding can be measured, and the quality of the welds can be determined without omission based on each individual welding current value, and further, the quality of the welds can be determined based on the overall welding current value.

FIG. 1 is a configuration diagram of an intermittent seam welding measuring device and a welding power source according to an embodiment of the present invention. FIG. 2 is a timing chart showing the repetition of energization and pauses in intermittent seam welding by a welding power source according to an embodiment of the present invention. FIG. 3 is a timing chart showing the setting of the measurement time and the pause time by the measurement setting unit of the intermittent seam welding measuring device according to the embodiment of the present invention. FIG. 4 is a timing chart showing the repetition of measurement of the welded state of the workpiece and calculation processing by the measurement circuit of the intermittent seam welding measuring device according to the embodiment of the present invention. FIG. 5 is a timing chart showing the judgment outputs when the judgment is bad and when the judgment is good after the measurement and calculation process shown in FIG. 4 are repeated. FIG. 6 is a flowchart showing the process of the welding power supply according to the embodiment of the present invention. FIG. 7 is a flowchart showing the processing of the intermittent seam weld measuring device according to the embodiment of the present invention.

Hereinafter, an intermittent seam weld measuring device and an intermittent seam weld measuring method according to an embodiment of the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same parts are given the same reference numerals and the description will be omitted.
(Basic configuration of intermittent seam welding measuring device)

Figure 1 is a diagram showing the configuration of an intermittent seam welding measurement device and a welding power source according to an embodiment of the present invention. This embodiment will be described with reference to Figure 1.

The welding power source 1 is a power source for intermittent seam welding, and as shown in FIG. 1, includes a welding current setting unit 11, a welding current control unit 12, an ignition pulse generating circuit 13, thyristors 14a, 14b, and a display unit 15. One end of a primary winding P of the transformer T is connected to one end of a single-phase AC power source (hereinafter abbreviated as AC power source) not shown, and the other end of the primary winding P is connected to the other end of the AC power source via the thyristors 14a, 14b. The welding power source 1, the transformer T, and the rotating electrodes 4a, 4b constitute an intermittent seam welding device for intermittently seam welding the workpiece 5.

Rotary electrodes 4a, 4b are connected to both ends of the secondary winding S of the transformer T. A welding current is supplied to the rotary electrodes 4a, 4b from an AC power source via the transformer T and the thyristors 14a, 14b.

In intermittent seam welding, the workpiece 5 is sandwiched between the disk-shaped rotating electrodes 4a, 4b and pressurized. While rotating the rotating electrodes 4a, 4b, a welding current is passed through the electrodes, and the workpiece 5 is heated by the electrical resistance. Furthermore, by moving the rotating electrodes 4a, 4b, the workpiece 5 is continuously joined while shifting the welding points.

The welding current setting unit 11 sets the magnitude of the welding current for performing intermittent seam welding, the welding time (current flow time) of the welding current, and the welding pause time. The welding current control unit 12 controls the magnitude of the welding current set by the welding current setting unit 11, the welding time (current flow time) of the welding current, and the welding pause time, and outputs a control signal to the ignition pulse generating circuit 13.

The ignition pulse generating circuit 13 generates an ignition pulse based on a control signal from the welding current control unit 12, and outputs the ignition pulse to the gates of the thyristors 14a and 14b. The thyristors 14a and 14b are turned on in response to the ignition pulse from the ignition pulse generating circuit 13, thereby causing a welding current to flow. The display unit 15 displays the magnitude of the welding current, the welding time (current flow time) of the welding current, and the welding pause time.

The transformer T has an electromagnetically coupled primary winding P and secondary winding S, and transforms the AC voltage of the AC power source and outputs it to the secondary winding S. The current sensor 3 is configured by having a coil wound around a toroidal core through which the secondary winding S of the transformer T passes, and detects the welding current flowing through the secondary winding S and outputs the detected welding current to the current trigger circuit 23.

The measuring device 2 includes a measurement setting unit 21, a main calculation processing unit 22, a current trigger circuit 23, a current sensor 3, a waveform restoration circuit 24, a secondary current measuring circuit 25, a secondary voltage measuring circuit 26, a judgment output unit 27, and a display unit 28.

The measurement setting unit 21 is composed of an input unit such as a touch panel or an operation panel, and sets a measurement time and a measurement pause time that are the same as the welding time and the welding pause time set in the intermittent seam welding device in the intermittent seam welding measurement device when welding the welding object 5 by repeating a welding time during which a current flows through the welding object 5 and a welding pause time during which the current does not flow. Since the welding time of the welding power source is 3 cycles as shown in FIG. 2, the measurement time is also set to 3 cycles as shown in FIG. 3. Since the welding pause time of the welding power source is 1 cycle as shown in FIG. 2, the measurement pause time is also set to 1 cycle as shown in FIG. 3. The measurement time is the time for measuring the current value of the welding current flowing on the secondary winding S side of the transformer T.

The main calculation processing unit 22 is composed of a CPU (central processing unit) and stores the measurement time and measurement pause time set by the measurement setting unit 21 in a memory (not shown), and outputs the measurement time and measurement pause time to the secondary current measurement circuit 25.

The current trigger circuit 23 obtains a welding measurement start trigger, which is the start of current flow, from an analog current differential waveform obtained from the time differential output of the measured current, which is the induced voltage detected by the current sensor 3.

The waveform restoration circuit 24 includes an operational amplifier circuit and an integrating circuit, and amplifies the analog current differential waveform detected by the current sensor 3 using the operational amplifier circuit, and integrates the amplified current differential waveform using the integrating circuit to restore the current waveform.

The secondary current measurement circuit 25 corresponds to the measurement circuit of the present invention, and is equipped with an A/D converter (analog/digital converter), and inputs the welding measurement start trigger obtained by the current trigger circuit 23 and the measurement time set by the measurement setting unit 21 from the main calculation processing unit 22.

The secondary current measurement circuit 25 converts the current waveform restored by the waveform restoration circuit 24 into a digital signal using an A/D converter and measures the value of the current flowing through the secondary winding S from the time of the welding measurement start trigger until the measurement time has elapsed. In other words, the process of measuring the welding condition of the welding object 5 is repeated.

The secondary voltage measurement circuit 26 measures the voltage value between the rotating electrodes 4a and 4b and outputs the measured voltage value to the main calculation processing unit 22.

The main calculation processing unit 22 performs a process of calculating the effective current value, the arithmetic mean effective current value, and the peak current value based on the current measurement values measured by the secondary current measurement circuit 25 during the period from after the measurement time has elapsed until the measurement pause time has elapsed. The main calculation processing unit 22 performs a process of calculating the effective voltage value, the arithmetic mean effective voltage value, and the peak voltage value based on the voltage measurement values measured by the secondary voltage measurement circuit 26 during the period from after the measurement time has elapsed until the measurement pause time has elapsed.

The judgment output unit 27 judges the welding state of the workpiece 5 based on the effective current value, arithmetic mean effective current value, current peak value, effective voltage value, arithmetic mean effective voltage value, and voltage peak value obtained by the main calculation processing unit 22. The display unit 28 displays the calculation results of the main calculation processing unit 22 and displays the judgment results of the judgment output unit 27.

Next, the operation of the seam welding measuring device and welding power source configured in this manner will be explained with reference to the drawings.

First, the operation of the welding power source 1 will be described with reference to the timing chart shown in FIG. 2 showing the repeated energization and pause of intermittent seam welding by the welding power source 1, and the flowchart shown in FIG. 6 showing the processing of the welding power source 1.

First, the welding current setting unit 11 sets the magnitude of the welding current for performing intermittent seam welding, the welding time (current flow time) of the welding current, and the welding pause time (step S11).

The welding current control unit 12 controls the magnitude of the welding current set by the welding current setting unit 11, the welding time (current flow time) of the welding current, and the welding pause time. The ignition pulse generating circuit 13 outputs the generated ignition pulse to the thyristors 14a and 14b.

The thyristors 14a and 14b pass a welding current from the AC power source to the primary winding P of the transformer T in response to the ignition pulse. Furthermore, the welding current flows through the secondary winding S of the transformer T, and this welding current flows through the disk-shaped rotating electrodes 4a and 4b. This starts intermittent seam welding (step S13).

In this case, as shown in FIG. 2, the welding current goes through a transition state in which the current value increases and decreases repeatedly, with welding time (current flow time) from time t0 to t6, welding pause time from time t6 to t8, welding time from time t8 to t14, and welding pause time from time t14 to t16.

Next, the welding current control unit 12 and the ignition pulse generating circuit 13 stop the intermittent seam welding and pause the welding (step S15).

Next, the measuring device 2 determines whether the intermittent seam welding has ended (step S17). If the intermittent seam welding has not ended in step S17, the measuring device 2 returns to step S11 and performs the processes from step S11 to step S15. If the intermittent seam welding has ended, the measuring device 2 ends the process.

Next, the operation of the measuring device 2 will be explained with reference to the timing charts shown in Figures 3, 4, and 5, and the flow chart of the measuring device 2 shown in Figure 7.

First, the measurement setting unit 21 sets a measurement time and a measurement pause time that are the same as the welding time and the welding pause time, respectively, in intermittent seam welding, which welds the workpiece 5 by repeating a welding time during which a current is passed through the workpiece 5 and a welding pause time during which the current is not passed (step S21).

In this case, as shown in FIG. 3, the measurement setting unit 21 repeatedly sets the measurement time from time t0 to t6, the measurement pause time from time t6 to t8, the measurement time from time t8 to t14, the measurement pause time from time t14 to t16, and so on. In other words, the measurement device 2 sets the measurement time and measurement pause time in synchronization with and equal to the welding time and welding pause time set by the welding power source 1.

Next, the main calculation processing unit 22 stores the measurement time and the measurement pause time set by the measurement setting unit 21 in the storage device, and sets the measurement timing based on the measurement time and the measurement pause time (step S23). The main calculation processing unit 22 outputs the measurement timing information to the secondary current measurement circuit 25.

The current trigger circuit 23 determines whether the start of the welding current flow has been detected from the current differential waveform detected by the current sensor 3 (step S25). If the current trigger circuit 23 detects the start of the welding current flow (the rising edge of the welding current value), it obtains a welding measurement start trigger as the start of the welding current flow.

Next, the waveform restoration circuit 24, the secondary current measurement circuit 25, the secondary voltage measurement circuit 26, and the main calculation processing unit 22 start measuring the welding current value and the welding voltage value (step S27).

Specifically, the waveform restoration circuit 24 amplifies the analog current differential waveform detected by the current sensor 3 using an operational amplifier circuit, and integrates the amplified current differential waveform using an integration circuit to restore the current waveform.

The secondary current measurement circuit 25 inputs the welding measurement start trigger obtained by the current trigger circuit 23 and the measurement time set by the measurement setting unit 21. As shown in FIG. 4, the secondary current measurement circuit 25 converts the current waveform restored by the waveform restoration circuit 24 into a digital signal by an A/D converter and measures the secondary current value (welding current value) from the welding measurement start trigger time (e.g., time t0) to the measurement time (e.g., time t6). The secondary current measurement circuit 25 also measures the welding time (step S29).

As shown in FIG. 4, the secondary current measurement circuit 25 measures the current value from time t0 until the measurement time from time t6 has elapsed, and measures the current value from time t8 until the measurement time from time t14 has elapsed.

When the welding time (measurement time) has elapsed, the measuring device 2 stops the waveform restoration circuit 24, the secondary current measurement circuit 25, and the secondary voltage measurement circuit 26 (step S31). That is, the measurement pause times are times t6 to t8 and times t14 to t16.

The main calculation processing unit 22 calculates the effective value, etc. based on the current measurement value measured by the secondary current measurement circuit 25 from the end of the measurement time until the end of the measurement pause time (for example, time t78 in Figure 4) (step S33).

As shown in FIG. 4, the main calculation processing unit 22 calculates the effective current value, etc., during the measurement time t0 to t6 from the end of the measurement time from t6 to t8 until the end of the measurement pause time, and calculates the effective current value, etc., during the measurement time from t14 to t16 from the end of the measurement time from t8 to t14.

Here, the main calculation processing unit 22 calculates the effective value, arithmetic mean effective value, and peak value of the welding current value, etc. from the measured values of the welding current value, etc. for each measurement time.

The judgment output unit 27 individually judges whether the welding object 5 is good or defective based on the calculation results obtained by the main calculation processing unit 22 (step S35). The judgment of whether the welding object 5 is good or defective is performed, for example, as follows. As shown in FIG. 5, if the peak value of the current value is within a predetermined range, it is determined to be a "good item" (times t0 to t6). If the peak value of the current reaches a first threshold value that is greater than the predetermined range, it is determined to be a "defective item" (times t8 to t14).

In addition, the determination of whether the welding object 5 is a good or bad product can be made in multiple stages, for example, into "good product", "bad product NG1", and "bad product NG2", based on a first threshold value and a second threshold value. In addition, the determination of whether the welding object 5 is a good or bad product can be made in multiple stages, for example, into "good product", "bad product NG1", "bad product NG2", and "bad product NG3", based on a first threshold value, a second threshold value, and a third threshold value.

Then, the judgment output unit 27 stores the individual judgment results, i.e., the judgment results for each measurement time, in the storage device (step S37).

Next, the judgment output unit 27 judges whether the intermittent seam welding has been completed (step S39). If the intermittent seam welding has not been completed in step S39, the judgment output unit 27 returns to step S25 and performs the processes from step S25 to step S37.

When intermittent seam welding is completed, the judgment output unit 27 performs an overall judgment that combines the individual judgments (step S41). The judgment output unit 27 then stores the overall judgment result in the storage device (step S43).

Next, some examples of judgment outputs when the welding object 5 is judged to be defective will be explained with reference to the timing chart in Figure 5.

In the first example, if the welding object 5 is defective, the judgment output unit 27 outputs a defective judgment after the intermittent seam welding is completed. This makes it possible to output a judgment on the entire welding.

In the second example, when the welding object 5 is defective, the judgment output unit 27 outputs a defective judgment (Low: NG) and continues to output the defective judgment. In other words, if it is determined that the welding object 5 is defective, it can immediately output a defective judgment and stop welding.

In the third example, the judgment output unit 27 outputs a defective judgment (Low: NG) when the welding object 5 is defective, and then stops outputting the defective judgment when the welding condition of the welding object 5 becomes good (High: within the judgment range). This makes it possible to determine the parts that are judged to be defective welds.

In the fourth example, the judgment output unit 27 outputs a judgment after welding is completed if the judgment of the welding object 5 is good.

In this way, according to the intermittent seam welding measuring device of the embodiment, the measurement setting unit 21 sets a measurement time and a measurement pause time that are the same values as the welding time and the welding pause time set in the intermittent seam welding device in the intermittent seam welding measuring device when welding the workpiece 5 by repeating a welding time during which a current is passed through the workpiece 5 and a welding pause time during which the current is not passed.

The secondary current measurement circuit 25 measures the current value from the welding measurement start trigger time until the measurement time has elapsed. The main calculation processing unit 22 performs calculation processing of the measured value from the time the measurement time has elapsed until the measurement pause time has elapsed.

In other words, the main calculation processing unit 22 calculates the measurement value during a preset pause time, i.e., from the time the measurement time has elapsed until the measurement pause time has elapsed, so that the entire weld can be measured and calculated. Therefore, it is possible to judge the quality of the weld based on each individual welding current value, and further to judge the quality of the weld based on the overall welding current value.

In addition, the secondary current measurement circuit 25 converts the current waveform restored by the waveform restoration circuit 24 into a digital signal and measures the current value from the welding measurement start trigger time until the measurement time has elapsed, so that the welding current value, which is the secondary current, can be accurately and repeatedly measured for the measurement time.

In addition, when the measuring device 2 is connected to the welding power source 1 that supplies current to the welding device via a communication network, that is, when the intermittent seam welding device and the intermittent seam welding measuring device can communicate information via the communication network, the measuring device 2 receives signals indicating the welding time and welding pause time from the welding power source 1 via the communication network. The measurement setting unit 21 can set the measurement time and measurement pause time to be the same values as the welding time and welding pause time received from the welding power source 1 via the communication network.

The present invention is not limited to the intermittent seam welding measurement device according to the embodiment described above, and various modifications are possible without departing from the spirit and scope of the present invention.

REFERENCE SIGNS LIST 1 welding power source 2 measuring device 3 current sensors 4a, 4b rotating electrode 5 welding object 11 welding current setting section 12 welding current control section 13 ignition pulse generating circuits 14a, 14b thyristors 15, 28 display section 21 measurement setting section 22 main calculation processing section 23 current trigger circuit 24 waveform restoration circuit 25 secondary current measuring circuit 26 secondary voltage measuring circuit 27 judgment output section

Claims (7)

An intermittent seam welding measuring device for welding a workpiece by repeating a welding period during which a welding current is applied to the workpiece and a welding pause period during which the welding current is not applied to the workpiece,
a measurement setting unit that sets a measurement time and a measurement pause time that are the same values as the welding time and the welding pause time that are set in the intermittent seam welding apparatus;
a current trigger circuit for detecting a current value of the welding current to obtain a welding measurement start trigger;
a measurement circuit that measures a current value of the welding current during a period from a welding measurement start trigger time obtained by the current trigger circuit until a measurement time set by the measurement setting unit has elapsed;
a calculation processing unit that performs calculation processing of the measurement value measured by the measurement circuit during the period from the end of the measurement time to the end of the measurement pause time;
a judgment output unit for judging a welding state of the workpiece based on the calculated value obtained by the calculation processing unit; and
An intermittent seam weld measuring device comprising: a waveform restoration circuit that restores a current waveform by integrating an analog current differential waveform of the current value of the welding current;
2. The intermittent seam welding measurement device according to claim 1, wherein the measurement circuit converts the current waveform restored by the waveform restoration circuit into a digital signal to measure the welding current during a period from the welding measurement start trigger time to the measurement time elapses. The intermittent seam welding measuring device according to claim 1 or 2, wherein the judgment output unit outputs a judgment failure after the intermittent seam welding is completed if the welding condition of the welding object is poor. The intermittent seam welding measuring device according to claim 1 or 2, wherein the judgment output unit outputs a judgment failure when the welding state of the welding object is poor, and continues to output the judgment failure. The intermittent seam welding measuring device according to claim 1 or 2, wherein the judgment output unit outputs a judgment failure when the welding condition of the welding object is poor, and then stops the judgment failure output when the welding condition of the welding object becomes good. receiving, when the intermittent seam welding measuring device is connected to the intermittent seam welding device via a communication network, a signal indicating the welding time and the welding pause time from the intermittent seam welding device via the communication network;
6. The intermittent seam weld measuring device according to claim 1. A method for measuring intermittent seam welding in which a workpiece is welded by repeating a welding period during which a welding current is applied to the workpiece and a welding pause period during which the welding current is not applied,
setting a measurement time and a measurement pause time that are the same as the welding time and the welding pause time that are set in the intermittent seam welding device, respectively;
Detecting the current value of the welding current to obtain a welding measurement start trigger;
Measure the current value of the welding current during the period from the obtained welding measurement start trigger time until the set measurement time has elapsed;
performing arithmetic processing of the measured values during the period from the end of the measurement time to the end of the measurement pause time;
determining a welding state of the workpiece based on the calculated value;
Intermittent seam weld measurement method.

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