JPH11151580A - Device for judging normal/defective condition of weld zone and mash seam welding machine using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of quickly judging normal or defective joined condition of a weld zone. SOLUTION: Each end 21a, 22a of two oppositely facing steel plate materials 21, 22 is superposed on each other, and forcibly fed between the roller electrodes 32, 33 of a mash seam welding machine 30. The temperature distribution is measured for the mash seam weld zone 24 by means of an infrared radiation thermometer 40, the temperature distribution pattern is analyzed for the feeding direction of the steel plate materials 21, 22, and the normal/defective joined condition is judged on the weld zone 24. As a result, the joined condition can be grasped for the inside of the weld zone 24 for which analysis is impossible from the temperature distribution in the direction of the plate width. Additionally, since the condition can be grasped continuously in the feeding direction of the steel plate materials 21, 22, the normal/defective joined condition can also quickly be discriminated for the weld zone 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for judging the quality of a welded portion for judging a welding state of mash seam welding performed on an overlapped portion of ends of two opposite steel sheet materials.
And a mash seam welding machine using the apparatus for determining the quality of a weld.

[0002]

2. Description of the Related Art Conventionally, a method called mash seam welding has been known as one of the welding methods for seam welding a steel sheet material. This is because, as shown in FIG. 11, the overlapping portion of the two steel sheet materials 91 and 92 is placed on the roller electrode 9 from above and below.
A welding method in which the welding current is applied while being sandwiched between the plates 5 and 96 and pressurized, so that the welding portion is crushed by the rotating roller electrodes 95 and 96 simultaneously with the resistance welding by the nugget 93. In this type of resistance welding, as in the case of spot welding, heat generated by electric resistance between the steel plate materials 91 and 92 is joined to each other by a nugget 93 formed by solidifying and then solidifying the boundary portion between the steel plates.

Since it is known that the state of formation of the nugget 93 is affected by changes in the welding current and the pressing force applied to the roller electrodes, in mash seam welding, the welding current and the welding conditions are used as processing conditions. It is common practice to control the pressure. That is, as shown in FIG. 12, "nugget cracks" (also referred to as dust and blisters) caused by an excessive welding current with respect to the pressing force, and "insufficient strength" caused by an insufficient welding current with respect to the pressing force occur in the welded portion. The mash seam welding is performed by setting the welding current and the pressing force as the processing conditions not to be performed. Then, as shown in FIG. 11, the formation state of the nugget 93 formed at the boundary between the two steel sheet materials 91 and 92 is determined by, for example, a crack generated on the surface of the welded portion by a ball head overhang test by extracting a predetermined number of the nuggets 93. The condition is checked ex post facto by inspection, and the welding quality of mash seam welding is controlled.

[0004]

However, according to the above-mentioned method of performing mash seam welding by controlling the welding current and the pressing force, the pulsation of the power supply voltage due to the fluctuation of the power supply load in the factory and the deterioration of the roller electrode wear. Since the welding current and the pressing force set as the processing conditions may not be obtained, the formation state of the nugget 93 cannot always be controlled. "Nugget cracking" or "insufficient strength" may occur in the part. Further, as described above, since the formation state of the nugget 93 is confirmed ex post facto by sampling inspection every predetermined number and the welding quality of the mash seam welding is controlled, "nugget cracking" and "insufficient strength"
It takes a long time from the occurrence of a defect to its discovery, and there is a problem that it is difficult to improve the yield due to defective products manufactured during that time.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and an object of the present invention is to provide a welded part quality judging apparatus capable of quickly judging the quality of a welded joint. It is in. Another object of the present invention is to
An object of the present invention is to provide a mash seam welding machine capable of reducing welding defects.

[0006]

In order to achieve the above object, in the apparatus for judging the quality of a welded portion according to the present invention, the ends of two opposite steel plate materials are overlapped with each other and pressure-fed between roller electrodes. The apparatus for determining the quality of a welded portion to be subjected to mash seam welding, wherein a temperature distribution of the welded portion is measured by an infrared radiation thermometer, and a temperature distribution pattern in a feed direction of the steel sheet material is analyzed to determine a bonding state of the welded portion. Is a technical feature.

According to a second aspect of the present invention, in the first aspect, the quality determination is performed based on a temperature distribution width and a maximum temperature at or above a predetermined temperature of the temperature distribution pattern. I do.

According to a third aspect of the present invention, there is provided a mash seam welding machine in which ends of two opposed steel sheet materials are overlapped with each other and are welded by pressure-feeding between roller electrodes. A mash seam welding machine for determining the quality of the welded portion by the quality determination device for a welded portion according to claim 1 or 2, wherein as a result of the quality determination, when the amount of energy input to the roller electrode is excessive, the roller electrode is determined. The present invention is characterized in that the current supplied to the roller electrode is decreased, and the current supplied to the roller electrode is increased when the amount of energy supplied to the roller electrode is insufficient as a result of the pass / fail determination.

According to a fourth aspect of the present invention, in the mash seam welding machine according to the third aspect, the pressure applied by the roller electrode applied to the steel plate material is increased when a current supplied to the roller electrode is reduced. It is a technical feature that the current supplied to the roller electrode is decreased when it is increased.

According to the first aspect of the present invention, the temperature distribution in the conveying direction of the welded portion is measured at regular time intervals by the infrared radiation thermometer. Therefore, by analyzing the temperature distribution, the temperature state in the welded portion can be grasped. it can. Further, since the temperature distribution pattern in the feed direction of the steel sheet material is analyzed, the temperature distribution of the welded portion sequentially welded by the roller electrodes can be continuously grasped. Thereby, the connection state of the welded portion by mash seam welding can be continuously grasped in the feed direction of the steel sheet material.

According to the second aspect of the present invention, the quality of the welded joint is determined based on the temperature distribution width and the maximum temperature at a predetermined temperature or higher in the temperature distribution pattern.
It can be grasped as long as the welding state can be specified by the two parameters.

According to a third aspect of the present invention, control is performed such that the current supplied to the roller electrode is reduced or increased according to the excess or shortage of the energy input to the roller electrode, based on the result of the determination of the quality of the welded joint. I do. This allows
Poor connection of the weld can be prevented.

According to the fourth aspect of the present invention, control is performed such that the pressing force by the roller electrode applied to the steel plate material increases or decreases in accordance with the decrease or increase of the current supplied to the roller electrode. Accordingly, when the current supplied to the roller electrode is reduced, that is, when it is desired to reduce the amount of energy to be supplied and to suppress the heat generation of the welded portion, the pressing force by the roller electrode increases, so that the electric resistance between the steel sheet materials is reduced. be able to. Also, when increasing the current supplied to the roller electrodes, that is, when it is desired to increase the amount of energy to be applied and to promote the heat generation of the welded portion, the electric resistance between the steel sheet materials should be increased because the pressure applied by the roller electrodes decreases. Can be.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the apparatus for judging the quality of a welded portion of the present invention and a mash seam welding machine using the same will be described below with reference to FIGS. First, the configuration of a welding part quality determination device (hereinafter, referred to as “quality determination device”) 20 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the pass / fail determination device 20 includes an infrared radiation thermometer 40 and a microcomputer (hereinafter referred to as a “microcomputer”) 50, and the steel plate materials 21 and 22 joined by the mash seam welding described above. Is analyzed by analyzing the temperature distribution pattern of the welded portion 24 to determine whether the connection state of the welded portion 24 is good or not. That is, the ends 21a and 22a of the two sheet steel members 21 and 22 facing each other are overlapped with each other, and the roller electrodes 32 and 33 of the mash seam welding machine 30 described later are used.
The temperature distribution of the welded portion 24 subjected to mash seam welding by pressure feeding is measured by an infrared radiation thermometer 40, and the temperature distribution pattern in the feed direction of the steel plate materials 21 and 22 is analyzed to determine whether the bonding state of the welded portion 24 is good or bad. judge.

The infrared radiation thermometer 40 mainly includes a condenser 42
And an infrared solid-state image pickup device or the like built in the main body section 44 to detect infrared rays within a predetermined range of wavelengths optically collected by the light collecting section 42, thereby detecting the measurement target object. It measures the surface temperature distribution. That is, by mounting the infrared radiation thermometer 40 to a mash seam welding machine 30 described later and measuring the welded portions 24 of the steel plate materials 21 and 22, the red hot portion 2 having a relatively high temperature is measured.
6 and infrared rays emitted from the vicinity thereof can be detected, and the surface temperature distribution of the welded portion 24 can be grasped as a thermal image. Thermal image data measured by the infrared radiation thermometer 40 is sent to the microcomputer 50 as appropriate. In the present embodiment, the infrared thermometer 40 is set to about 50 cm from the weld 24.
At a distance of 1.

The microcomputer 50 mainly comprises a display section 52, an operation section 54, and a main body section 56. Various types of thermal image data sent from the infrared radiation thermometer 40 are set by the operation section 54 and the like. Image analysis is performed according to the conditions, and the thermal image after the analysis processing is displayed on the display unit 52 in color and shape. Data processing such as image analysis is performed by a main unit 56. As shown in FIG. 2, the main unit 56 mainly includes a CPU 56a, a memory 56b, and an external storage device 56c.
And interfaces 56d and 56e.

The memory 56b stores a program for performing image analysis of thermal image data, a program for performing a quality judgment process described later, and the like, and stores the program via a system bus (not shown).
It is connected to the PU 56a. Interface 5
The display unit 52 and the operation unit 54 described above, and an external storage device 56c that stores a filed image analysis program and the like are connected to 6d, and control data exchange between the CPU 56a and each of them. I have. On the other hand, the interface 56e has the infrared radiation thermometer 40 described above.
Is connected, and the thermal image data of the welding portion 24 sent from the infrared radiation thermometer 40 is sequentially transferred to the CPU 56a.

Next, the main structure of a mash seam welding machine 30 using the above-described quality judgment device 20 will be described with reference to FIGS.
A description will be given with reference to FIG. As shown in FIG. 1, a main part of the mash seam welding machine 30 includes a roller electrode 32,
33 and a welding power source 35.
The superposed part (21a,
22a) is sandwiched between roller electrodes 32 and 33 from above and below,
It is configured such that a welding current by the welding power source 35 can be conducted while pressurizing. Further, the infrared radiation thermometer 40 of the above-described quality judgment device 20 is attached at a position where the welded portion 24 can be photographed during or immediately after welding, for example, at the side surface direction of the roller electrodes 32 and 33. Device 2
0, the welding current from the welding power source 35 and the roller electrode 32,
The pressurizing force by 33 is controlled.

Roller electrodes 32 and 33 formed in a disk shape
Are rotatable about the shaft portions 34a and 34b, and are positioned with a predetermined gap therebetween so that their respective peripheral surfaces face each other. A variable pressure type pressurizing device (not shown) is connected to the shaft portions 34a and 34b that rotatably support the roller electrodes 32 and 33, and the opposing interval between the roller electrodes 32 and 33 is reduced by the pressurizing device. The shaft portions 34a and 34b are biased in the directions. As a result, the steel plate materials 21 and 22 inserted between the roller electrodes 32 and 33 at substantially constant speed are pressed by the roller electrodes 32 and 33 at a predetermined pressure (for example, 8 kN). Note that the pressurizing device has the above-described CP so that the pressing force can be set to an arbitrary value.
U56a, as shown in FIG.
It is connected to the CPU 56a via the interface 56e.

The welding power source 35 includes the shaft portions 34a, 3
4b, the output of which is connected to the roller electrodes 32, 3
3, a welding power source 35, a shaft portion 34a, a roller electrode 32, a steel sheet material 21, and a steel sheet material 2 are applied.
2. A welding current flows through a closed circuit formed by the path of the roller electrode 33, the shaft portion 34b, and the welding power source 35. Most of the current flowing in this closed circuit is
This current is converted to, for example, 10 k
By setting the A order, the vicinity of the boundary between the steel sheet materials 21 and 22 is heated to a temperature higher than the melting temperature of iron, and
1, 22 can be resistance welded. That is, FIG.
As shown in FIG. 7, a region 28 where the vicinity of the boundary between the steel sheet materials 21 and 22 once melted by the heat generated by the welding current is solidified again.
(Hereinafter referred to as “nugget 28”).
1, 22 are joined together. The welding power source 35
Can be set to an arbitrary value.
As shown in FIG. 2, the welding power source 35 is controlled by the CPU 56a via the interface 56e.
It is connected to the.

Next, the welding portion 24 by the pass / fail judgment device 20
3 and 9, the welding current control and the pressing force control processing by the mash seam welding machine 30 will be described. Each process shown in the flowcharts of FIGS. 3 and 4 is executed by the microcomputer 50 described above, the pass / fail judgment device 20 displays the pass / fail judgment result on the display unit 52 of the microcomputer 50, and the mash seam welding machine 30 A pressurizing device for the roller electrodes 32 and 33 or a welding power source 35 is controlled.

As shown in FIG. 3, in the pass / fail judgment process, an initialization process is first performed in step 60. In this initialization processing, not only the work area and the like of the memory 56b of the microcomputer 50 are initialized, but also, for example, the thicknesses, materials, threshold temperature Tth, and nugget formation of the steel plate materials 21 and 22 input from the operation unit 54. Processing for setting various condition data such as the temperature Tng as predetermined parameters is also included. Next, image analysis processing is performed in step 61. That is, a process of analyzing the thermal image data transmitted from the infrared radiation thermometer 40 via the interface 56e according to various conditions set by the operation unit 54 or the like is performed. In this step 61, the thermal image after the analysis processing as shown in FIG. 5 may be displayed on the display unit 52 in color and shape. Thus, the operator can recognize the thermal image of the welded portion 24 during the quality determination in real time.

Next, at step 63, the maximum temperature Tmax is analyzed from the thermal image data, and then at step 65, it is determined whether or not the maximum temperature Tmax is higher than the threshold temperature Tth. This threshold temperature Tth is set to, for example, 600 ° C. As a result, a joint having an insufficient strength shown in FIG. 9D caused by the temperature distribution pattern shown in FIG. 8 is detected. That is, in the temperature distribution pattern shown in FIG. 8, the maximum temperature Tmax is the threshold temperature Tth600 ° C.
Is lower than 580.2 ° C.,
Is determined to be No, the processing is shifted to the insufficient strength display processing (S67). In the insufficient strength display process of step 67, the display unit 52 displays that the determination result is "insufficient strength", and notifies the operator of the effect using an alarm sound or the like. On the other hand, the maximum temperature Tmax
Is higher than the threshold temperature Tth (for example, the maximum temperature Tmax 798. of the temperature distribution pattern shown in FIG. 5).
2 ° C., the maximum temperature Tmax 7 in the temperature distribution pattern shown in FIG.
64.4 ° C., the maximum temperature T of the temperature distribution pattern shown in FIG.
max 687.4 ° C.), the process proceeds to step 69.

In step 69, the measured maximum temperature Tma
It is determined whether or not x has reached a preset nugget formation temperature Tng. The nugget formation temperature Tng is set to, for example, 700 ° C. As a result, the junction in the nugget formation failure state shown in FIG. 9C caused by the temperature distribution pattern shown in FIG. 7 is detected. That is, FIG.
In the temperature distribution pattern shown in FIG. 7, the maximum temperature Tmax is 687.4 ° C. lower than the nugget formation temperature Tng 700 ° C.
Therefore, the determination is No in step 69, and the processing shifts to the nugget formation defect display processing (S71). In the nugget formation defect display processing in step 71, the display unit 52 indicates that the judgment result is “nugget formation defect”.
Is displayed on the screen and an alarm sound or the like is used in combination to notify the worker. On the other hand, the maximum temperature Tma
x is determined to be higher than the nugget formation temperature Tng (for example, the maximum temperature Tmax of the temperature distribution pattern shown in FIG. 5).
If the temperature is 798.2 ° C., the maximum temperature Tmax of the temperature distribution pattern shown in FIG.

Next, at step 73, the temperature distribution width Wtp at or above the threshold temperature Tth is analyzed from the thermal image data. Then, at step 75, whether the temperature distribution width Wtp is equal to or less than a predetermined allowable distribution width Wmax. Determine whether or not. The allowable distribution width Wmax is, for example, the steel plate material 21, 2
The feed direction is set to 10 mm. As a result, a joint portion in which a crack 29 occurs in the nugget 28 shown in FIG. 9A caused by the temperature distribution pattern shown in FIG. 5 is detected. That is, in the temperature distribution pattern shown in FIG. 5, the temperature distribution width Wtp above the threshold temperature Tth.
Is larger than the allowable distribution width Wmax,
Is determined to be No by the nugget crack display processing (S7
The processing shifts to 7). In the nugget cracking display process of step 77, the judgment result is "nugget cracking" is displayed on the display unit 52, and the operator is notified of the fact using an alarm sound or the like. On the other hand, in step 75,
When it is determined that the temperature distribution width Wtp at or above the threshold temperature Tth is equal to or less than the allowable distribution width Wmax, that is, when the temperature distribution width Wtp is equal to or less than the allowable distribution width Wmax according to the temperature distribution pattern shown in FIG. It is determined that a good nugget 28 as shown in FIG. 9 (B) is formed, and in step 79, the display unit 52 indicates that the determination result is "non-defective".
And a series of processing ends.

Here, the criterion for the quality judgment in the quality judgment processing described above will be described with reference to FIG. FIG.
9 is a sectional view in the feed direction of the welded portion 24 shown in FIG. 9 (FIG. 9A).
9 is a nugget crack, FIG. 9 (B) is a good product, FIG. 9 (C) is a poor nugget formation, and FIG.
9 schematically shows the temperature distributions in the feed direction 1 and 22, that is, the temperature distributions in the feed direction in FIGS. 5 to 8. As described above, the parameters used for the pass / fail judgment are the steel plate material 21,
22 of the temperature distribution pattern for the feed direction of No. 22
The temperature distribution width Wtp is equal to or higher than the predetermined threshold temperature Tth. Then, the quality is judged from the steepness of the triangle formed with the maximum temperature Tmax as the apex with the temperature distribution width Wtp as the base. That is, the joining state of the welded portion 24 is determined from the degree of the temperature gradient with respect to the feed direction of the steel sheet materials 21 and 22. It is assumed that the feed rates of the steel sheet materials 21 and 22 are constant as described above.

Therefore, as apparent from FIG. 10, in FIG. 10 (B), the temperature distribution of the non-defective product in a good bonding state forms an acute triangle with the maximum temperature Tmax as the apex. On the other hand, the temperature distribution of the nugget cracks in FIG. 10 (A) forms a trapezoid having the flat maximum temperature Tmax on the upper side or a triangle with a relatively gentle hypotenuse. In FIG. 10 (C), even if the shape is a steep triangle similar to that of a good product, the maximum temperature Tmax at the apex of the triangle is sharp.
Does not reach the nugget formation temperature Tng, so that a triangle having a low height is formed. Further, in FIG. 10 (D), since the maximum temperature Tmax is equal to or lower than the threshold temperature Tth, a trapezoid having a completely crushed shape is formed.

By analyzing the temperature distribution in the feed direction of the steel sheet materials 21 and 22 in this manner, it is possible to grasp the bonding state in the welded portion 24 that cannot be analyzed from the temperature distribution state in the sheet width direction. That is, as shown in FIG. 5 to FIG. 8, the difference in the connection state in the welded portion 24 is unlikely to appear as a shape characteristic in the temperature distribution in the plate width direction, and thus the shape characteristic is notably reduced in the feed direction. By analyzing the temperature distribution, the quality determination criterion is made simple so that the connection state in the welded portion 24 can be grasped.

The reference numerals 26a, 26 shown in FIGS.
b, 26c, 26d, 26e, 26f, 26g, 26
The relationships between h, 26i, 26j, 26k, 26m, and 26n and the respective temperature ranges are as follows. Symbol 26a
Is in the range of 725 ° C or higher, and reference numeral 26b is in the range of 675 ° C or higher.
The range below 5 ° C., 26c is a range from 600 ° C. to less than 675 ° C., 26d is a range from 540 ° C. to less than 600 ° C., 26e is a range from 515 ° C. to less than 540 ° C., and 26f is 465 ° C. to 515 ° C. Less than, code 26
g ranges from 415 ° C. to less than 465 ° C.
Range of 65 ° C. or more and less than 415 ° C., reference numeral 26i is 290 ° C.
Not less than 365 ° C., reference numeral 26j is 240 ° C. or more 2
Range below 90 ° C, 26k is 190 ° C or higher and 240 ° C
, A reference numeral 26m indicates a range of 165 ° C or more and less than 190 ° C, and a reference numeral 26n indicates a range of less than 165 ° C.

As shown in FIG. 4, in the welding current control and the pressing force control processing by the mash seam welding machine 30, steps 67, 71, 77, and 79 corresponding to the respective display processings in the above-mentioned quality judgment processing are respectively performed. This is changed to welding current control processing or pressure control processing. Therefore, in FIG. 4, steps for performing the same processing as the above-described pass / fail determination processing are denoted by the same reference numerals, and description thereof is omitted.

Step 67 shown in FIG. 3, that is, processing to replace the insufficient strength display processing, includes processing to increase the welding current in step 81 and step 8 as shown in FIG.
3 is a process for reducing the pressing force. Since the determination result was "insufficient strength", the amount of energy applied to the roller electrodes 32 and 33 was significantly short, and a nugget was formed at the joint in the welded portion 24 as shown in FIG. 9 (D). It is speculated that they have not. Accordingly, control is performed to increase the welding current by the welding power source 35 and decrease the pressing force of the roller electrodes 32 and 33 to enable the formation of a good nugget. The reason for increasing the welding current is to cause the vicinity of the boundary between the steel plates 21 and 22 to generate heat above the melting temperature of iron, and to reduce the pressing force of the roller electrodes 32 and 33 because the pressure between the steel plates 21 and 22 is reduced. This is for increasing the value of the contact resistance formed at the contact portion to further promote heat generation. When each of the processes in steps 81 and 83 is completed, the process is shifted to step 61 in order to measure the result and perform the pass / fail judgment again. As a result, feedback control is performed.

The step 71 shown in FIG. 3, that is, the process for replacing the nugget formation defect display process is a process for increasing the welding current in step 85 as shown in FIG.
That is, since the determination result is “nugget formation failure”, it is assumed that the nugget 28 is not sufficiently formed at the joint in the welded portion 24 as shown in FIG. Is performed to increase the welding current. The reason why the welding current is increased is to increase the amount of energy applied to the roller electrodes 32 and 33 so that the vicinity of the boundary between the steel plate materials 21 and 22 is heated to a temperature equal to or higher than the melting temperature of iron, similarly to step 81 described above. When the processing of step 85 is completed, the processing is shifted to step 61 to measure the result and determine the quality again, and the feedback control is performed.

Step 77 shown in FIG. 3, that is, replacing the nugget crack display processing is processing for reducing the welding current in step 87 as shown in FIG. Since the result of the determination is “nugget crack”, it is presumed that a crack 29 has occurred in the nugget 28 at the joint in the welded portion 24 as shown in FIG. This crack 2
No. 9 occurs because the amount of energy input to the roller electrodes 32 and 33 is excessive, so that a process for reducing the amount of input energy is performed. That is, control for reducing the welding current by the welding power supply 35 is performed. Step 87
Is completed, the processing is shifted to step 61 to measure the result and determine the quality again, and the feedback control is performed.

Step 79 shown in FIG. 3, that is, the step of replacing the non-defective item display processing is performed at step 61 as shown in FIG.
This is the flow of processing for shifting to. Thereby, the welding power source 3
The welding current control process and the welding force are applied to the portion of the welded portion 24 during or immediately after the next welding, while maintaining the current supplied by 5 and the applied pressure of the roller electrodes 32 and 33 at predetermined values, respectively. Control processing is performed. In the above-described control, the steel sheet materials 21, 2
In order to increase the value of the contact resistance formed at the contact portion between the two and promote heat generation, control to reduce the pressing force of the roller electrodes 32 and 33 was performed in step 83, but the control of the roller electrodes 32 and 33 was performed. By increasing the pressure, the value of the contact resistance between the steel sheet materials 21 and 22 may be reduced to suppress heat generation.

As described above, according to the pass / fail determination device 20 of the present embodiment, the temperature distribution of the welded portion 24 is measured by the infrared radiation thermometer 40, and the temperature distribution pattern in the feed direction of the steel sheet materials 21, 22 is analyzed. I do. Thereby, the bonding state in the welded portion 24, which cannot be analyzed from the temperature distribution state in the sheet width direction, can be grasped, and it can be grasped continuously in the feed direction of the steel sheet materials 21, 22. Therefore, there is an effect that the quality of the connection of the welded portion 24 can be quickly determined.

Further, according to the pass / fail judgment device 20 of the present embodiment, the pass / fail judgment of the connection state of the welded portion 24 is made by the steel plate material 2.
This is performed based on the maximum temperature Tmax of the temperature distribution pattern in the feed directions 1 and 22 and the temperature distribution width Wtp at or above the predetermined threshold temperature Tth. This makes it easy to grasp the shape that can be specified by these two parameters, for example, the connection state of the welded portion 24 according to a triangular temperature distribution pattern formed with the temperature distribution width Wtp as the base and the maximum temperature Tmax as the apex. Can be. Therefore, there is an effect that the quality of the detailed connection state of the welded portion can be quickly determined.

Further, according to the mash seam welding machine 30 of the present embodiment, if the amount of energy to be applied to the roller electrodes 32 and 33 is excessive, the roller electrode 32, 33, or reduce the current supplied to the roller electrodes 32, 3
3 to control the welding power supply 35 or the pressure-variable type pressurizing device so as to increase the pressing force.
When the amount of energy to be supplied to the electrode 33 is insufficient, the current supplied to the roller electrodes 32 and 33 is increased, or the welding power supply 35 or the pressure-variable pressure is applied so as to reduce the pressing force by the roller electrodes 32 and 33. Control the device.
As a result, the heat generation of the welded portion 24 can be suppressed by the amount of the decrease in the current or the contact resistance between the steel sheet materials 21 and 22, and the electric resistance or the contact resistance between the steel sheet materials 21 and 22 increases. As a result, heat generation of the welded portion 24 can be promoted. Therefore, it is possible to control the heat generation of the welded portion 24 according to the result of the determination of the quality of the connection state of the welded portion 24, and it is possible to reduce welding defects due to mash seam welding.

[0038]

According to the first aspect of the present invention, the temperature distribution of the welded portion is measured by an infrared radiation thermometer, and the temperature distribution pattern in the feed direction of the steel sheet material is analyzed to judge the quality of the welded portion. In addition, the joining state of the welded portion by mash seam welding can be continuously grasped in the feed direction of the steel sheet material. Thereby, there is an effect that the quality of the connection of the welded portion can be quickly determined.

According to the second aspect of the present invention, the quality of the welded portion is judged based on the temperature distribution width and the maximum temperature at a predetermined temperature or higher in the temperature distribution pattern.
It is relatively easy to grasp the connection state of the welded portion according to the temperature distribution pattern that can be specified by the two parameters. Thereby, there is an effect that the quality of the detailed connection state of the welded portion can be quickly determined.

According to the third aspect of the present invention, the current supplied to the roller electrode is controlled to decrease or increase in accordance with the excess or shortage of the energy input to the roller electrode, based on the result of the determination of the quality of the welded joint. Therefore, it is possible to prevent poor connection of the welded portion. Thereby, there is an effect that welding defects due to mash seam welding can be reduced.

According to the fourth aspect of the present invention, when the amount of energy to be supplied is reduced to suppress the heat generation of the welded portion, the pressing force by the roller electrode increases, so that the electric resistance between the steel sheet materials decreases. As a result, the heat generated at the welded portion can be suppressed more than the supply current is reduced by the decrease in the electric resistance between the steel sheet materials. Further, when the amount of energy to be input is increased to promote the heat generation of the welded portion, the electric resistance between the steel sheet materials increases because the pressing force by the roller electrode decreases. As a result, the increase in the electric resistance between the steel sheet materials can promote the heat generation of the welded portion more than the increase in the supply current. Therefore, it is possible to precisely control the heat generation of the welded portion in accordance with the result of the determination of the quality of the connection of the welded portion, and it is possible to further reduce welding defects due to mash seam welding.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a configuration of a mash seam welding machine using a pass / fail determination device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a microcomputer main body and peripheral devices of the microcomputer of the pass / fail determination device according to the embodiment;

FIG. 3 is a flowchart illustrating a pass / fail determination process performed by the pass / fail determination device according to the embodiment;

FIG. 4 is a flowchart showing a welding current control and a pressing force control process by the mash seam welding machine of the present embodiment.

FIG. 5 is an explanatory diagram illustrating an example (a nugget crack) of a thermal image after an analysis process performed by the pass / fail determination device according to the embodiment;

FIG. 6 is an explanatory diagram showing an example (a conforming product) of a thermal image after an analysis process performed by the acceptability determination apparatus of the embodiment;

FIG. 7 is an explanatory diagram illustrating an example of a thermal image (nugget formation failure) after an analysis process performed by the pass / fail determination device according to the embodiment;

FIG. 8 is an explanatory diagram illustrating an example (insufficient intensity) of a thermal image after an analysis process performed by the pass / fail determination device according to the embodiment;

9 (A) is a cross section of a welded portion showing a nugget crack, FIG. 9 (B) is a non-defective product, FIG. 9 (C) is a defective nugget, and FIG. FIG.

10 (A) is a diagram showing a temperature distribution in a feeding direction of each of nugget cracks, FIG. 10 (B) is a non-defective product, FIG. 10 (C) is a defective nugget, and FIG. 10 (D) is insufficient strength. FIG.

FIG. 11 is an explanatory diagram illustrating the concept of mash seam welding.

FIG. 12 is a characteristic diagram showing the quality of a welding state with respect to changes in welding current and pressure applied to a roller electrode.

[Explanation of symbols]

 Reference Signs List 20 pass / fail judgment device 21, 22 steel plate material 21a, 22a end 24 welding portion 30 mash seam welding machine 32, 33 roller electrode 35 welding power source 40 infrared radiation thermometer 50 microcomputer Tth threshold temperature (predetermined temperature) Tmax maximum temperature Wtp Temperature distribution width

Claims (4)

[Claims] An apparatus for judging the quality of a welded portion for performing mash seam welding by superposing ends of two opposite steel sheet materials on each other and feeding the material between roller electrodes by pressure, wherein the temperature distribution of the welded portion is determined by infrared rays. A good or bad judgment device for a welded part, wherein the quality of the welded part is judged by measuring a radiation thermometer and analyzing a temperature distribution pattern in a feed direction of the steel sheet material to determine whether or not the welded part is connected. 2. The apparatus according to claim 1, wherein the quality determination is performed based on a temperature distribution width and a maximum temperature of the temperature distribution pattern at a predetermined temperature or higher. 3. The end portions of two opposed steel plate materials are overlapped with each other, and are pressed and welded between roller electrodes.
A mash seam welding machine for judging the quality of the welded part by the welded part quality judging device according to claim 1 or 2, wherein as a result of the quality judgment, when an energy amount to be supplied to the roller electrode is excessive. Mash seam welding characterized by reducing the current supplied to the roller electrode, and increasing the current supplied to the roller electrode when the amount of energy input to the roller electrode is insufficient as a result of the pass / fail determination. Machine. 4. The pressure applied by the roller electrode applied to the steel plate material is increased when the current supplied to the roller electrode is decreased, and is decreased when the current supplied to the roller electrode is increased. The mash seam welding machine according to claim 3, characterized in that: