JP2001038474A - Device and method for checking welding condition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To check qualities of total number under a non-destructive condition by judging good/bad of a welding condition in a resistance welding portion at high accuracy. SOLUTION: In this welding device wherein resistance welding is performed while a core wire of a cable is nipped between an electrode chip 32A arranged at the upper part of holding blocks 42, 43 and an electrode chip 32B arranged at the lower part of a clearance D, a thermocouple 11 abutting the electrode chip 32B is arranged. The thermocouple 11 is pressure welded to the electrode chip 32B by a spring 5. Temperature of the electrode chip 32B at the time of resistance welding is measured by the thermocouple 11. When a peak temperature of the chip is above a given reference value, it is judged to be a good product, and when the peak temperature is below the reference value, it is judged to be a failured good. The thermocouple 11 may be retreated by a spring when the electrode chip 32B is exchanged (set). Instead of the thermocouple 11, an optical fiber and an infrared ray detector, or a bare thermocouple built in an electrode chip may be used as a temperature sensor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding machine in which a welding current is applied to a pair of electrodes for pressurizing a welded portion of a material to be welded, and resistance welding is performed on the welded portion of the material to be welded using resistance heating. The present invention relates to an apparatus and a method for inspecting a welding state of resistance welding for inspecting a welding state of the welding portion.

[0002]

2. Description of the Related Art Conventionally, as a resistance welding machine, for example, there is one which welds exposed core wires of a pair of insulated wires. This resistance welding machine includes an electric wire set jig made of ceramic or the like having a gap corresponding to the width of a core wire, and a pair of electrode chips made of tungsten or the like arranged above and below the gap and having a thickness of the gap. . The lower electrode tip is arranged at a lower portion in the gap between the wire setting jigs, and the upper electrode tip is configured to move up and down by an air cylinder or the like so as to be inserted into the gap between the wire setting jigs. And
Insert a pair of core wires vertically into the wire set jig, insert the upper electrode tip into the gap between the wire set jigs, press the core wires from above and below, and apply a welding current between the electrode tips. Accordingly, the core wires are welded to each other by utilizing the resistance heat generation.

[0003]

As a non-destructive inspection method for inspecting the quality of a welding state, such as the welding strength (adhesion force between core wires), of a welded portion welded by a resistance welding machine as described above, a method for detecting whether or not a current is applied to a current-carrying part is disclosed. A method is used in which the resistance value between the electrode chips is determined from the voltage and current value between the chips, and when this resistance value satisfies a predetermined condition, it is predicted that the product is good.In particular, the core wire is formed by twisting a plurality of copper wires. When formed, the contact resistance varies due to the non-uniform arrangement of the copper wires, and the resistance value between the electrode chips in the initial stage of energization also varies. For this reason, it is difficult to accurately predict the welding state, and there is a problem in performing a quality inspection of all the welded parts. SUMMARY OF THE INVENTION It is an object of the present invention to determine the quality of a welding state of a resistance welded portion with high accuracy, and to enable quality inspection of all parts in a non-destructive state.

[0004]

According to a first aspect of the present invention, there is provided a welding condition inspection apparatus, wherein a welding portion of a material to be welded is pressed by a pair of electrodes, and a welding current is applied to the welding portion by the electrodes.
A welding state inspection device that inspects a welding state of a resistance welding machine configured to perform resistance welding on the welding portion by using resistance heating due to the welding current, and detects a temperature of at least one of the pair of electrodes. A temperature sensor for detecting the welding state of the material to be welded based on a peak temperature of the temperature of the electrode detected by the temperature sensor.

According to the study of the present inventor, the electrode temperature is sampled during resistance welding, and the peak temperature of the electrode, that is, the highest temperature is examined. It was found that the adhesive strength of the welded portion did not reach the predetermined value, but when the peak temperature was equal to or higher than the predetermined value, the adhesive force of the welded portion maintained the predetermined value. Therefore, according to the welding condition inspection apparatus of the first aspect, it is possible to determine a good product and a defective product at the peak temperature.

According to a second aspect of the present invention, there is provided a welding state inspection apparatus.
A peak temperature detecting means for detecting a peak temperature of the temperature detected by the temperature sensor; and a temperature for comparing the peak temperature detected by the peak temperature detecting means with a predetermined reference temperature for determination. Comparing means for judging whether or not the welding state of the welding portion is good or not based on a comparison result of the temperature comparing means. By appropriately setting the reference temperature for use, a good product and a defective product can be determined from the comparison result of the temperature comparing means.

A third aspect of the present invention provides a welding condition inspection apparatus.
Or wherein the temperature sensor is a thermocouple that is in contact with the electrode.
According to the welding condition inspection apparatus of (1), the same operation and effect as those of claim 1 or 2 can be obtained, the temperature of the electrode can be detected with high accuracy, and a highly accurate determination can be made.

According to a fourth aspect of the present invention, there is provided a welding state inspection apparatus.
And a biasing means for biasing the thermocouple toward the electrode. According to the welding state inspection apparatus of the fourth aspect, the temperature of the electrode is further reduced than that of the third aspect. Detection can be performed with high accuracy, and more accurate determination can be performed.

According to a fifth aspect of the present invention, there is provided a welding state inspection apparatus.
5. The welding condition inspection apparatus according to claim 4, wherein said biasing means is a first spring, wherein said biasing means is coaxial with said thermocouple and holds said thermocouple slidably in its axial direction. A first holding portion which is detachable at a predetermined position in the axial direction with respect to a wire set jig for fixing the electrode, and which is coaxial with the thermocouple and slidably moves in the axial direction thereof. A second holding portion provided on the wire setting jig and a second holding portion provided between the first holding portion and the second holding portion for biasing the thermocouple to a side opposite to the electrode. A spring for generating a biasing force of the first spring by pivoting the first holding portion to the predetermined position, wherein the biasing force at this time is greater than the biasing force of the second spring. The thermocouple is pressed against the electrode. The features.

According to the welding condition inspection apparatus of the fifth aspect, the same operation and effect as those of the fourth aspect are obtained, and the workability when attaching and detaching the electrode to and from the wire set jig is improved. That is, when the first holding portion (sensor set knob) is pivotally attached to the predetermined position, the thermocouple is pressed against the electrode by the first spring. When the electrode is removed, the first holding portion is moved. Remove from place. As a result, the urging force of the first spring is eliminated, and the thermocouple is separated from the electrode by the urging force of the second spring that urges the electrode opposite to the electrode.

According to a sixth aspect of the present invention, there is provided a welding state inspection apparatus.
Or the temperature sensor is characterized in that the temperature sensor comprises an optical fiber whose end face is disposed to face the electrode, and temperature detecting means for detecting a temperature by infrared light transmitted through the optical fiber. According to the welding state inspection apparatus of the sixth aspect, the same operation and effect as those of the first or second aspect can be obtained, and the temperature of the electrode can be detected with high accuracy, and a highly accurate determination can be performed. .

According to a seventh aspect of the present invention, there is provided a welding state inspection apparatus.
Or the temperature sensor is a thermocouple partially embedded in the electrode. According to the welding condition inspection apparatus of claim 7, the temperature sensor is a thermocouple partially embedded in the electrode.
The same operation and effect as those described above can be obtained, and the temperature of the electrode can be detected with high accuracy, so that highly accurate determination can be performed.

According to an eighth aspect of the present invention, there is provided a method for inspecting a welding condition, wherein a welding portion of a material to be welded is pressurized by a pair of electrodes, a welding current is applied to the welding portion by the electrodes, and resistance heat generated by the welding current is utilized. A welding state inspection method for inspecting a welding state of a resistance welding machine configured to perform resistance welding on the welding portion, wherein a temperature of at least one of the pair of electrodes is detected, and a temperature of the detected temperature of the electrode is detected. The welding state of the material to be welded is inspected based on the peak temperature. According to the welding state inspection method of the eighth aspect, the same operation and effect as those of the first aspect can be obtained.

According to a ninth aspect of the present invention, there is provided a welding state inspection method.
Wherein the peak temperature of the electrode temperature is compared with a predetermined reference temperature for determination, and the quality of the welding state of the welded portion is determined based on the comparison result. According to the welding state inspection method of the ninth aspect, the same operation and effect as those of the second aspect can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 8 is a front view of the resistance welding machine to which the present invention is applied, FIG. 9 is a side view of the resistance welding machine, and FIG.
FIG. 7 is a diagram showing an insulated wire (hereinafter referred to as an “electric wire”) and an electrode tip as a material to be welded in the embodiment. In this resistance welding machine, core wires 100a and 100a 'made of a plurality of twisted copper wires of electric wires 100 and 100' are overlapped and resistance-welded, and a support 20b is erected on a base 20a and a support 20b is provided. The machine control unit 2 is provided at the upper end of the unit 20b.

An air cylinder 21 is provided on the front of the machine control unit 2.
Is attached, and the piston rod 2 of the air cylinder 21 is
1a, an upper electrode portion 3 is provided via an electrode holder 22.
A is attached, and this electrode portion 3A is
Is moved in the up-down direction by the drive.
The electrode section 3A is connected via an ounce copper plate 23 to a later-described welding transformer (power supply) built in the machine control section 2. At the lower end of the air cylinder 21, an arm 30 that is bent rearward and extends downward is attached. The lower end of the arm 30 is protruded forward, and the lower electrode portion 3B is attached to the upper end thereof, and the wire set jig 4 is disposed above the electrode portion 3B. The electrode section 3B
Is connected via an ounce copper plate 24 to the welding transformer built in the machine control unit 2.

FIG. 6 is a partial cross-sectional side view of the electrode portions 3A and 3B and the wire setting jig 4, FIG. 7 (A) is a plan view of the wire setting jig 4, and FIG. 7 (B) is a rear view. is there. Each electrode part 3A,
3B is a columnar chromium steel body 31A, 31B and electrode tips 32A, 32B formed of rectangular parallelepiped tungsten.
, Respectively. The electric wire setting jig 4 includes a fixing portion 41 fixed to the chrome steel body 31B of the lower electrode portion 3B, and holding blocks 42 and 43 slidably disposed on the fixing portion 41. A portion in contact with the lower electrode portion 3B of the fixing portion 41 and the holding blocks 42, 4
Reference numeral 3 is formed of an insulating member such as ceramic. The upper end of the electrode chip 32B of the lower electrode portion 3B projects slightly (about 1 to 2 mm) from the fixing portion 41, and the projecting portion of the electrode chip 32B is sandwiched by the holding blocks 42 and 43.

The holding block 42 is pressed against the electrode chip 32B by a handle 44 and a ball screw 45, and the holding block 43 is pressed by a ball screw 46 to the electrode chip 32B.
Is pressed against. A gap D having a width equivalent to the thickness of the electrode chip 32B is formed by the opposing surfaces of the holding blocks 42 and 43, and the electric wires 100 and 10 are formed in the gap D.
By setting the welded portions of the core wires 100a, 100a 'at 0', lowering the upper electrode portion 3A and inserting the electrode tips 32A into the gap D, the core wires 100a, 100a '
A predetermined pressing force is applied to the welded portion a ', and a welding current is caused to flow.

As shown in FIG. 7A, a cross-section of the holding block 43 is formed with a groove 43a on the lower surface of the holding block 43. Is attached. Further, an end block 48 having a through hole 48a extending from the rear end of the holder 47 is attached to the rear of the fixing portion 41. A thermocouple 11 as a temperature sensor is slidably inserted in the groove 43a of the holding block 43, the holder 47 and the through hole 48a of the end block 48 in the axial direction. End is through hole 4
It is drawn out through 8a. Further, a spring 5 as an urging means is provided in a portion inside the through hole 48a of the thermocouple 11, and the thermocouple 11 is urged by the spring 5 toward the electrode tip 32B. Is pressed against the electrode tip 32B.

With the above configuration, the holding blocks 42, 4
When the welding portion of each of the core wires 100a, 100a 'of the electric wires 100, 100' is set in the gap D formed by the
Is driven to lower the upper electrode portion 3A, and the electrode tip 32A is inserted into the gap D. Thereby, the core wire 10
A predetermined pressure is applied to the 0,100 'welding portion, and further, a welding current is applied to the welding portion via the electrode tips 32A, 32B of the electrode portions 3A, 3B. The thermocouple 11 and the welding state inspection device 1 including the respective parts shown in the block diagram of FIG.
Is detected, and the welding state inspection device 1 determines whether the welding state of the welding portion is good or not.

As shown in FIG. 1, the welding state inspection apparatus 1 of this embodiment amplifies the output of a thermocouple 11 and converts an analog voltage signal output from the amplifier 12 into digital voltage data. A / D converter 13, I /
An I / O circuit 14, a CPU 15, a ROM 16, a RAM 17, and a display unit 18.
5, the ROM 16, the RAM 17, and the display unit 18 constitute a microcomputer. CPU 15 is ROM1
6 based on the control program stored in the RAM 1
The control is performed using the working area No. 7. Specifically, temperature data (voltage data) corresponding to the temperature of the electrode tip 32B by the thermocouple 11 obtained by the A / D converter 13 is sampled via the I / O circuit 14. In addition, the quality of the welding condition is determined based on the sampled temperature data. Then, the sampled temperature data is graphically displayed on the display unit 18, and the determination result is displayed on the display unit 18.

A sequencer 10a and a welding timer 10
b, a welding transformer 10c, and a solenoid valve 10d are built in the mechanical control unit 2 of the resistance welding machine,
Performs a predetermined sequence control on the resistance welding machine side according to a preset control program. For example, the air cylinder 21 is driven by controlling the opening and closing of a solenoid valve 10d connected to a compressed air source (not shown), and the upper electrode portion 3A
Control the elevation of the vehicle. In addition, by starting the welding timer 10b, the energization of the welding transformer 10c for a predetermined time is controlled. Further, the sequencer 10a transmits the start signal and the holding end signal of the resistance welding machine to the welding state inspection device 1
And the CPU 15 of the welding condition inspection apparatus 1 uses the start signal and the holding end signal as triggers for starting and completing sampling of the temperature data.

FIG. 3 is a flowchart of a control program executed by the sequencer 10a.
In step S1, the start switch is monitored, and when the start switch is turned on, a start signal of the welding machine is output to the welding state inspection apparatus 1 in step S12, and a welding sequence operation is executed in step S13. In this welding sequence operation, the solenoid valve 10d is controlled to drive the air cylinder 21, and the upper electrode portion 3A is lowered so that the electric wires 100, 10
Initial pressure is applied to the welded portions of the core wires 100a, 100a 'of 0'. Next, a start instruction is output to the welding timer 10b to supply a welding current to the welding timer 10b.
When the welding is completed after the current supply for a predetermined time is completed, the pressurized state is maintained for a predetermined time (holding pressurization). Then, when this welding sequence operation is completed, a holding end signal of the welding machine is output to the welding state inspection device 1 in step S14, and the process is ended.

FIG. 2 is a flowchart of a control program executed by the CPU 15. First, at step S21,
It monitors whether the start signal of the welding machine, that is, the measurement start trigger is detected, and when the measurement start trigger is detected,
In step S22, the temperature data of the electrode tip 32B is collected (sampled), and in step S23, it is determined whether a holding end signal of the welding machine, that is, a measurement completion trigger is detected. If the measurement completion trigger is not detected, step S2
2, the temperature data collection is continued, and if a measurement completion trigger is detected, a peak temperature value corresponding to the maximum temperature value is calculated from the temperature data collected in step S24.

Next, in step S25, it is determined whether or not the peak temperature value is within a preset reference value (not less than a predetermined reference value which is a reference temperature for determination). In step S28, an output of "OK" indicating that the product is non-defective is displayed on the display unit 18, and if it is not within the reference value, an output of "NG" indicating that the product is defective is displayed in the display unit 18 in step S27. And step S28
Proceed to. In step S28, it is determined whether or not the end is designated by turning off the power or the like. If the end is designated, the process ends. If not, the process returns to step S21.

FIG. 5 is a diagram showing a change over time in the measured temperature. When the energization is started, the temperature starts to rise, and after approximately 0.5 seconds from the end of the energization, the temperature reaches the peak temperature value (116).
° C), and then the temperature gradually decreases. At the time of collecting temperature data, a graph is displayed on the display unit 18 as shown in FIG.

The inventor of the present invention conducted an experiment for examining the relationship between the peak temperature value and the fixing force of the welded portion.
The following experimental results were obtained. Note that one point in the figure corresponds to one sample. As shown in the figure, when the peak temperature value is equal to or more than a predetermined value, the fixing force also becomes a substantially constant strong value, but when the peak temperature value is equal to or less than the predetermined value, the fixing force is weak. Therefore, if a peak temperature value as shown in the drawing is set as a reference value as a reference temperature for determination, the quality of the welded portion can be determined.

FIGS. 10 to 14 show a second embodiment in which a thermocouple is used as a temperature sensor. Members similar to those shown in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted.
This embodiment corresponds to claim 5. FIG.
0, in FIG. 11, the electric wire set jig 7 includes a fixing portion 71 fixed to the chrome steel body 31B of the lower electrode portion 3B,
There are holding blocks 72 and 73 slidably arranged on the fixing portion 71, and a portion in contact with the electrode portion 3 </ b> B on the lower side of the fixing portion 71 and the holding blocks 72 and 73 are formed of an insulating member such as ceramic. Have been. Lower electrode part 3
The upper end of the electrode chip 32B of B projects slightly (about 1 to 2 mm) from the fixed portion 71, and
The protruding portion of 2B is sandwiched between holding blocks 72 and 73. The holding blocks 72 and 73 are pressed against the electrode chip 32B by the same configuration as the handle 44 and the ball screws 45 and 46 in the above embodiment.

An elongated cylindrical sensor bracket 74 as a second holding portion is attached to a fixed portion 71 on a rear extension line of the groove 73a on the lower surface of the holding block 73. Further, an end block 75 having a through hole 75 a extending from the rear end of the sensor bracket 74 is attached to the fixing portion 71. The through hole 75a has a cylindrical shape, and a part of a sensor set knob 76 as a first holding portion is slidably fitted therein. And the thermocouple 11
Are the through hole 76a at the center of the sensor set knob 76, the through hole 75a of the end block 75, and the sensor bracket 7
4 through the center through hole 74a. The thermocouple 11 is slidable with respect to the sensor set knob 76 and the sensor bracket 74.

In the thermocouple 11, the sensor setting knob 7
6 and the sensor bracket 74, a stopper 83
A first spring 81 is disposed between the stopper 83 and the sensor set knob 76.
The second between the stopper 83 and the sensor bracket 74
A spring 82 is provided. The end block 75 is formed with two screw holes 75b and 75c penetrating from the upper surface thereof to the through holes 75a.
Ball plungers 84 and 85 are screwed into b and 75c.

FIG. 12 is a longitudinal sectional view (FIG. 12 (A)), a transverse sectional view (FIG. 12 (B)), and a front view (FIG. 12 (C)) of the sensor set knob 76. 12) is a sectional view taken along the line AA of FIG. 12 (A), and FIG. 12 (C) is a sectional view taken along the arrow B of FIG. 12 (A). The sensor set knob 76 has a substantially cylindrical sliding portion 76 that matches the inner diameter of the through hole 75a of the end block 75.
b, and a handle 76c having a diameter larger than that of the sliding portion 76b. The tip portion 76d of the sliding portion 76b (the handle portion 76d)
(the side opposite to c) has a circular cross-sectional shape, the outer peripheral surface is aligned with the through hole 75a, a V-groove 76e is formed in the outer peripheral surface, and the periphery of the tip is a chamfered tapered surface 76f. Further, the tip 76 of the sensor set knob 76
The upper surface of the portion between d and the handle portion 76c is partially deleted to form a stepped portion 76g.

FIG. 13 is a partial sectional view and a top view of the ball plungers 84 and 85.
Numeral 85 includes a cylinder a, a compression spring b disposed in the cylinder a, and a metal ball c. The inner diameter of the opening of the cylinder a is slightly smaller than the diameter of the metal ball c. The metal ball c is configured to partially protrude from the opening of the cylinder a in a state where the compression spring b is compressed. The peripheral side surface of the cylinder a is threaded, and the ball plungers 84 and 85
The end block 7 is formed by using a hex key d at the upper end of the
5 are screwed into the screw holes 75b and 75c.

With the above configuration, the sensor set knob 7
6 is slidable with respect to the through hole 75a of the end block 75. When the sensor set knob 76 is at the position shown in FIG. 10, a step 76g is formed as shown in FIG.
Abuts against the metal ball c of the ball plunger 85, and the sensor set knob 76 does not come out of the through hole 75a. When in the position shown in FIG. 11, the handle portion 76c comes into contact with the end face of the end block 75, and the metal ball c of the ball plunger 84 is inserted into the V groove 76 as shown in FIG.
e. Thereby, the sensor set knob 7
6 (first holding portion) is pivotally attached to a predetermined position.
The thermocouple 11 is pressed against the electrode tip 32B by the urging force of the spring 81.

That is, in the state of FIG. 10, both the first spring 81 and the second spring 82 are hardly elastically deformed, and there is almost no repulsive force of the first spring 81 against the sensor set knob 76 and the stopper 83. Also, there is almost no repulsive force of the second spring 82 against the sensor bracket 74 and the stopper 83. here,
Although the first spring 81 and the second spring 82 are made of the same material and have the same diameter and pitch, in the open state of FIG.
The length is set longer than 2. The state in which the sensor set knob 76 is pivotally attached to a predetermined position as shown in FIG. 11 is a state in which the thermocouple 11 abuts on the electrode tip 32B and further pushes the sensor set knob 76, and the first spring 81 Is shorter than the second spring 82. For this reason, the second spring 82 is
The elastic force given by the first spring 81 to the stopper 83 is larger than the elastic force given to the stopper 83, and the force corresponding to the difference between the elastic forces is the force with which the thermocouple 11 presses the electrode tip 32B.

In the state shown in FIG. 11, the first spring 8
The elastic force of the first and second springs 82 is applied to the sensor set knob 76. When the metal ball c of the ball plunger 84 is fitted in the V groove 76e as shown in FIG.
The characteristics of the first spring 81 and the second spring 82 are set so that the position of the sensor set knob 76 is fixed. Also, from the state of FIG. 10 to the state of FIG. 11, the metal ball c of the ball plunger 84 abuts on the tip of the sensor set knob 76. Since this tip has a tapered surface 76f, the sensor set The knob 76 can be pushed in easily.

When the handle 76c of the sensor set knob 76 is pulled from the state shown in FIG. 11, the metal ball c of the ball plunger 84 is forcibly disengaged from the V-groove 76e, and the sensor set knob 76 is moved to the position shown in FIG. State. At this time, the first spring 81 extends and the elastic force applied to the stopper 83 is weakened, and the elastic force of the second spring 82 moves the stopper 83 and the thermocouple 11 rightward in FIG. Then, the thermocouple 11 comes off the electrode tip 32B.

Therefore, when performing the work of attaching and detaching the electrode to and from the wire setting jig, the thermocouple 11 is pulled in from the position of the electrode tip 32 only by pulling the sensor set knob 76, so that the workability is improved. improves.

In the above embodiment, the thermocouple 11 is used as a temperature sensor for detecting the temperature of the electrode tip 32B. However, an optical fiber and an infrared detector as temperature detecting means may be used as the temperature sensor. . FIG.
FIG. 5 is a view showing a third embodiment using an optical fiber and an infrared detector.
It is a partial cross-sectional side view of the part. The same members as those in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted.

An elongated cylindrical holder 47 'is mounted on the extension line of the groove 43a on the lower surface of the holding block 43, and an optical fiber cable 51 is inserted into the holder 47'. The optical fiber 51a is inserted into the groove 43a of the holding block 43. The end face of the tip of the optical fiber 51a faces the vicinity of the upper end of the electrode tip 32B. The optical fiber cable 51 is guided to an infrared detector 52 provided in a welding state inspection device corresponding to this embodiment, and the infrared light transmitted through the optical fiber 51a is detected by the infrared detector 52. This infrared detector 5
No. 2 outputs a voltage corresponding to the intensity of infrared rays.
The temperature of the electrode tip 32B is detected based on the output voltage. The block diagram in this embodiment is shown in FIG.
Is simply replaced by an infrared detector 52, and the processing of collecting temperature data and determining the quality is the same as in the above-described embodiment, and a description thereof will be omitted.

FIG. 16 is a view showing a fourth embodiment using a thermocouple as a temperature sensor. Members similar to those shown in FIG. 6 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 16 (B) is a view as viewed from the direction of arrow a in FIG. 16 (A). Although the thermocouple 11 of the above embodiment is pressed against the electrode tip 31B, the naked thermocouple 61 may be directly embedded in the electrode tip 32A as in this embodiment. Also in this embodiment, the block diagram is the same as that of the above embodiment except that the thermocouple 11 of FIG. 1 is replaced by a bare thermocouple 61, and the processing of collecting temperature data and judging pass / fail is the same as in the above embodiment. I do. The holding block 43 'is different from the holding block 43 only in that no groove is formed on the lower surface. The bare thermocouple 61 is connected to the lower electrode tip 32B.
You may make it embed in.

In the above embodiment, the peak temperature detecting means for detecting the peak temperature of the temperature detected by the temperature sensor, and the temperature comparing means for comparing the peak temperature with a predetermined judgment reference temperature are provided. The functions are realized by a function obtained by the CPU executing the control program, but may be constituted by an electric circuit. For example, as a peak temperature detecting means, an analog hold circuit that holds a peak value of a signal detected by a thermocouple or an infrared detector and amplified by an amplifier, or holds a peak value of temperature data obtained by an A / D converter And a digital hold circuit. The temperature comparing means may be an analog comparator for comparing an output of the analog hold circuit with a predetermined analog signal (an input signal set corresponding to a reference temperature for determination), or a digital hold circuit. And a predetermined digital signal (input signal set corresponding to the reference temperature for determination).

[0042]

As described above, according to the first aspect of the present invention,
According to the welding state inspection device of the above or the welding state inspection method of the eighth aspect, the quality of the welding state of the welding portion of the resistance welding can be determined with high accuracy based on the peak temperature of the electrode (electrode tip) through which the welding current flows. It is possible to perform quality inspection of all products in a non-destructive state.

According to the welding state inspection apparatus of the second aspect or the welding state inspection method of the ninth aspect, by appropriately setting the reference temperature for judgment, the welding result of the resistance welding can be obtained from the comparison result of the temperature comparison means. The quality of the state can be determined with high accuracy, and all the quality inspections can be performed in the non-destructive state.

According to the welding condition inspection apparatus of the third aspect, the same effect as that of the first or second aspect can be obtained, and the temperature of the electrode can be detected with high accuracy, and a highly accurate determination can be performed. .

According to the fourth aspect of the present invention, since the urging means for urging the thermocouple toward the electrode is provided, the temperature of the electrode can be detected more accurately than in the third aspect. , It is possible to make a more accurate determination.

According to the welding condition inspection apparatus of the fifth aspect, the same effect as that of the fourth aspect is obtained, and the workability when attaching and detaching the electrode to and from the wire set jig is improved.

According to the welding condition inspection apparatus of the sixth aspect, the same effect as that of the first or second aspect can be obtained, and the temperature of the electrode can be detected with high accuracy, and highly accurate determination can be performed. .

According to the welding condition inspection apparatus of the seventh aspect, the same effect as that of the first or second aspect can be obtained, and the temperature of the electrode can be detected with high accuracy, so that a highly accurate determination can be made. .

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a flowchart of a control program executed by a CPU according to the embodiment.

FIG. 3 is a flowchart of a control program executed by a sequencer in the embodiment.

FIG. 4 is a view showing an experimental result of a relationship between a peak temperature value and a fixing force of a welded portion according to the embodiment.

FIG. 5 is a diagram showing a time change of a measured temperature according to the embodiment.

FIG. 6 is a partial cross-sectional side view of a part of an electrode part and a wire setting jig in the first embodiment.

FIG. 7 is a plan view and a rear view of the electric wire set jig according to the first embodiment.

FIG. 8 is a front view of the resistance welding machine to which the present invention is applied.

FIG. 9 is a side view of the resistance welding machine.

FIG. 10 is a partial cross-sectional side view of a part of a wire setting jig when a thermocouple according to a second embodiment is set.

FIG. 11 is a partial cross-sectional side view of a part of a wire set jig when a thermocouple is released in a second embodiment.

FIG. 12 is a longitudinal sectional view, a transverse sectional view, and a front view of a sensor set knob in a second embodiment.

FIG. 13 is a partial cross-sectional view and a top view of a ball plunger according to a second embodiment.

FIG. 14 is an enlarged view showing a relationship between a sensor set knob and a ball plunger according to the second embodiment.

FIG. 15 is a partial cross-sectional side view of a part of an electrode part and a wire setting jig according to a third embodiment.

FIG. 16 is a partial cross-sectional side view of a part of an electrode part and a wire setting jig in a fourth embodiment.

FIG. 17 is a diagram showing an insulated wire and an electrode tip as a material to be welded in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding state inspection apparatus 11 Thermocouple 15 CPU 16 ROM 17 RAM 32A Upper electrode tip 32B Lower electrode tip D Gap 5 Spring (biasing means) 51a Optical fiber 52 Infrared detector 61 Bare thermocouple

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kozo Kozai 206-1 Nunobikihara, Haibara-cho, Haibara-gun, Shizuoka Prefecture F-term (reference) 2G040 AA05 AB08 BA08 BA28 CA02 DA03 DA12 EA02 EA11 EB02 EC03 FA04 FA10 GA08 HA08 HA16

Claims (9)

[Claims] 1. A welding portion of a material to be welded is pressurized by a pair of electrodes, a welding current is applied to the welding portion by the electrodes, and the welding portion is resistance-welded by utilizing resistance heat generated by the welding current. A welding state inspection device for inspecting a welding state of the resistance welding machine, comprising: a temperature sensor that detects a temperature of at least one of the pair of electrodes; and a peak of the temperature of the electrode detected by the temperature sensor. A welding state inspection device for inspecting a welding state of the material to be welded based on a temperature. 2. A peak temperature detecting means for detecting a peak temperature of the temperature detected by the temperature sensor, and a temperature for comparing the peak temperature detected by the peak temperature detecting means with a predetermined reference temperature for determination. 2. The welding state inspection apparatus according to claim 1, further comprising a comparing unit, wherein the quality of the welding state of the welding portion is determined based on a comparison result of the temperature comparing unit. 3. The welding state inspection apparatus according to claim 1, wherein the temperature sensor is a thermocouple contacted with the electrode. 4. The welding condition inspection apparatus according to claim 3, further comprising an urging means for urging the thermocouple toward the electrode. 5. The welding condition inspection device according to claim 4, wherein said biasing means is a first spring, wherein said biasing means is coaxial with said thermocouple and holds said thermocouple slidably in its axial direction. A first holding portion detachable at a predetermined position in the axial direction with respect to a wire set jig for fixing the electrode; and a coaxial with the thermocouple so that the thermocouple is slidable in the axial direction. A second holding part provided between the first holding part and the second holding part, the second holding part provided between the first holding part and the second holding part, for urging the thermocouple to a side opposite to the electrode. A spring, wherein the first holding portion is pivotally attached to the predetermined position to generate an urging force of the first spring, so that the urging force at this time is larger than the urging force of the second spring. The thermocouple was pressed against the electrode DOO welding condition inspection apparatus according to claim 4, wherein. 6. The temperature sensor according to claim 1, wherein the temperature sensor comprises an optical fiber having an end face opposed to the electrode, and temperature detecting means for detecting a temperature by infrared rays transmitted through the optical fiber. Item 3. The welding state inspection device according to item 1 or 2. 7. The welding condition inspection apparatus according to claim 1, wherein the temperature sensor is a thermocouple partially embedded in the electrode. 8. A method in which a welding portion of a material to be welded is pressed by a pair of electrodes, a welding current is applied to the welding portion by the electrodes, and the welding portion is resistance-welded by utilizing resistance heat generated by the welding current. A welding state inspection method for inspecting a welding state of a resistance welder, wherein a temperature of at least one of the pair of electrodes is detected, and a peak temperature of the detected temperature of the electrode is used to detect a temperature of the workpiece. A welding condition inspection method, wherein the welding condition is inspected. 9. The method according to claim 1, wherein a comparison is made between a peak temperature of the temperature of the electrode and a predetermined reference temperature for determination, and the quality of the welding state of the welded portion is determined based on the comparison result. The welding state inspection method according to claim 8, wherein