JPH10137947A - Inspection method for resistance welding and resistance welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method for resistance welding and resistance welding equipment which can reduce a time and a manpower to inspect a joined state, conduct a high precision inspection without requiring a special inspection instrument for inspection only and does not require an additional equipment investment. SOLUTION: A large electric current for welding is caused to flow from a plus electrode 2 through a second work 13 and a first work 12 to a minus electrode 3, the first work 13 and the second work 12 are welded/joined. Successively, a DC voltage Vs is impressed between both electrodes 2, 3, based on the detected electric current value Is flowing between both electrodes 2, 3, a welding/joining state is obtained. That is, after welded/joined, normal/defective of the welded state is discriminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding inspection method and a resistance welding apparatus, and more particularly to an inspection method and a resistance welding apparatus for monitoring a joining state of a joint thereof.

[0002]

2. Description of the Related Art Conventionally, there is resistance welding as one of methods for joining works. Resistance welding is a method in which workpieces are overlapped with each other, an electric current is applied to a joining point of the workpieces, and pressure is applied to a joining point heated by the resistance heat to join the two workpieces.

[0003] By the way, it is important to inspect the joint state of the joint formed by the resistance welding in order to maintain the accuracy and reliability of the product. Among the inspection methods for inspecting the joint state of the joint, a nondestructive inspection method that does not damage the product is excellent. In a non-destructive inspection method, it is known to electrically measure a resistance value of a joint. In general,
When the joints are not sufficiently joined and there is unevenness, the resistance of the joints is large, and when the joint state of the joints is good, the resistance of the joints is small.

As one inspection method for electrically inspecting the joint state of the joint, a pair of probes (deep needles) is applied to both works sandwiching the joint, and a DC voltage is applied between the two probes. The current flowing at that time is measured. And
A resistance value is obtained from the measured current and the applied voltage, and the quality of the bonding state is determined based on the resistance value. The inspection method using this probe has higher detection accuracy than other inspection methods.

[0005]

However, the inspection apparatus using the above-mentioned probe is a facility equipment different from the resistance welding machine. Therefore, the product joined by the resistance welding machine must be transported to a remote place where the inspection device is located, and the joined state of the product must be inspected one by one, and the inspection work requires a great deal of time and labor.

Further, there is a problem that inspection equipment must be prepared separately from the resistance welding machine, a large amount of capital investment is required, and an installation place must be secured.
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to reduce the time and labor required for inspecting a bonding state and to require a dedicated inspection device only for inspection. It is an object of the present invention to provide a resistance welding inspection method and a resistance welding apparatus which can perform a highly accurate inspection and can eliminate unnecessary capital investment.

[0007]

According to a first aspect of the present invention, a first workpiece and a second workpiece overlapped from a first electrode.
After a current is applied to the second electrode through the workpiece and the two workpieces are welded to each other, an inspection voltage is applied between the two electrodes, and both workpieces are applied based on the value of the current flowing between the two electrodes. The purpose is to judge whether the welding state is good or bad.

According to a second aspect of the present invention, there is provided a first electrode which is in pressure contact with a first workpiece, a second electrode which is in pressure contact with a second workpiece, and A resistance welding apparatus connected to the second electrode and including a first power supply unit for supplying a current for welding the first workpiece and the second workpiece; A second power supply connected to the electrode and the second electrode and supplying a test voltage between the first and second electrodes; and measuring a current flowing through the circuit when the test voltage is applied. To drive and control the first power supply device,
And a control device for judging whether welding is good or not based on the current value detected by the ammeter when the second power supply device is driven. .

According to a third aspect of the present invention, in the resistance welding apparatus according to the second aspect, at least one of the first and second workpieces has a projection, and the projection is pressed. The purpose is to inspect the welding and the welding state in the state.

According to the first aspect of the present invention, the current flows from the first electrode to the second electrode via the first and second workpieces, so that the first welding is performed. The object and the second workpiece are welded and joined, and then a DC voltage is applied between the two electrodes to determine the welded state. Therefore, according to the resistance welding inspection method, it is possible to efficiently determine whether the welding state is good or not after using the same first and second electrodes to perform welding and joining.

According to the second aspect of the present invention, the pressed first workpiece and the second workpiece are provided with the first workpiece.
Since the current is supplied from the first power supply device by the first electrode and the second electrode, the first workpiece and the second workpiece are welded to each other. A voltage is supplied to the welded first and second workpieces from the second power supply device,
The current flowing at that time is measured by an ammeter. Therefore, the control device can determine, for example, a resistance value from the supplied voltage and the measured current. That is, in this resistance welding apparatus, joint welding and the inspection of the joint state can be efficiently performed using the same first and second electrodes.

According to the third aspect of the present invention, at least one of the first and second workpieces to be pressed forms a projection, so that the contact surface is small and the load is large. . Therefore, the contact surface efficiently generates resistance heat and is welded. Further, since the resistance value of the joint greatly varies depending on the quality of the bonding state, the quality of the bonding state can be easily determined.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a resistance welding apparatus for projection welding will be described below with reference to FIG. FIG. 1 is a principle explanatory view for explaining a resistance welding apparatus according to the present embodiment.

In FIG. 1, a resistance welding apparatus includes a fixed base 1,
A plus electrode 2 as a first electrode, a minus electrode 3 as a second electrode, a welding power supply 4 as a first power supply, a detection DC power supply 5 as a second power supply,
It comprises a DC ammeter 6, a control device 7, and the like. Above the fixed base 1, a plus electrode 2 and a minus electrode 3, which are respectively driven and controlled by a lifting device (not shown) in the vertical direction, are disposed spaced apart in the horizontal direction. The positive and negative electrodes 2 and 3 are formed of a cylindrical copper alloy having a flat bottom surface.
9 is connected to the welding power supply 4. The welding power supply device 4 is a power supply device for supplying a large current for welding, and is configured to flow a large current for welding from the positive electrode 2 side to the negative electrode 3 side.

The positive electrode 2 is connected to a positive power supply terminal of a DC power supply 5 for detection via a DC ammeter 6 by a wiring 10, and the negative electrode 3 is connected to a negative power supply terminal of the power supply 5 by a wiring 11. It is connected to the. The detection DC power supply 5 is a power supply for supplying a DC voltage,
A predetermined test DC voltage Vs is supplied between the two electrodes 2 and 3 for a predetermined time T.

A control device 7 controls the driving of the power supply devices 4 and 5 and controls the wiring 1 detected by the DC ammeter 6.
The current DC value Is flowing to 0 is input from the ammeter 6. The control device 7 first outputs a drive control signal for welding to the welding power supply device 4 and drives the power supply device 4 for a predetermined time. Next, the control device 7 outputs a drive control signal for detection to the DC power supply device 5 for detection, and drives the power supply device 5 for a predetermined time. Further, the control device 7 inputs the detection current value Is detected by the DC ammeter 6 while controlling the drive of the detection DC power supply device 5, monitors the detection current value Is at each time, and connects the connection. The quality is determined. Further, the control device 7 prints the determination result on the printer P and displays it on the display device D.

In the resistance welding apparatus configured as described above,
A plate-shaped first work 12 made of steel or the like as a first workpiece and a second plate-shaped aluminum alloy or the like formed with a projection (projection) portion 13a as a second workpiece. The work 13 is welded.

Next, the operation of the resistance welding apparatus configured as described above will be described. Negative electrode 3 is fixed base 1
The first work 12 is driven downward toward the work 12 with the first work 12 placed on the work 1, and the work 12 is sandwiched and fixed between the upper surface of the fixed base 1 and the bottom surface thereof. On the other hand, the plus electrode 2 is driven downward toward the work 13 with the projection 13a of the second work 13 in contact with the upper surface of the first work 12, and the work 13 is moved to the first work 12. 12 is fixed by being pinched and fixed between its upper surface and its own bottom surface, and pressed with a predetermined pressure. In this state, the control device 7 outputs a drive control signal to the welding power supply device 4.

In response to the drive control signal, the welding power supply 4 supplies a large current from the plus electrode 2 via the second work 13 and the first work 12 to the minus electrode 3 for a predetermined time. . Then, a portion having a small contact area, that is, the vicinity of the contact surface S where the projection 13a and the first work 12 are in contact with each other causes a large load, so that resistance heat is generated, and the projection 13a is melted. , By the pressing force. When the large current stops flowing,
The vicinity of the projection 13a solidifies, and the first work 12 and the second work 13 are welded and joined.

When the first work 12 and the second work 13 are joined, the joined state of the joined portion is maintained as it is, that is, in a state where both the works 12 and 13 are pressed by the electrodes 2 and 3. An inspection process is performed to inspect the device.

In the inspection process, the control device 7 outputs a drive control signal to the DC power supply device 5 for detection. In response to the drive control signal, the detection DC power supply 5 applies a constant inspection DC voltage Vs between the electrodes 2 and 3 for a fixed time T. The detected current value Is flowing at this time is measured by the DC ammeter 6, and the detected current value Is is output to the control device 7. Then, based on the measured value Is and the applied voltage Vs, the control device 7 obtains a resistance value Rs between the two electrodes 2 and 3. Based on the resistance value Rs, the control device 7 determines whether the bonding state at that time is good or not.

More specifically, when a test DC voltage Vs having a waveform as shown in FIG. 2 is applied, if the value of the current value Is is large, the resistance value Rs is small, and it is determined that the bonding state is good. Conversely, the inspection DC voltage Vs having a waveform as shown in FIG.
Is applied, if the value of the current value Is is small, the resistance value R
s is large, and it is determined that the bonding state is poor.

Therefore, in this resistance welding apparatus, both works 1
After joining the first and the second, the joining state of the joining portion can be inspected as it is. Next, features of the present embodiment configured as described above will be described below.

(1) In this embodiment, the plus electrode 2 and the minus electrode 3 are connected to the first workpiece 12 and the second workpiece 12 during welding.
Is applied, a DC voltage Vs is applied, and the resistance value Rs is measured. Therefore, this resistance welding device
The first work 12 and the second work 13 are welded and joined, and the joining state can be inspected.

(2) In the present embodiment, since the plus electrode 2 and the minus electrode 3 are used for both welding and inspection of the bonding state, an inspection device dedicated to inspection using a probe is provided. Eliminates the need. As a result, no large capital investment is required for the inspection device.

(3) In the present embodiment, since the resistance welding apparatus can perform both the welding and the inspection of the joining state by the same machine, there is no need to provide another inspection apparatus. Therefore, it is not necessary to secure a place for installing an inspection device dedicated to inspection, and there is no need to transport a workpiece to the inspection device, so that time and labor for transporting the workpiece are not expended.

(4) In the present embodiment, the second work 1
3 forms the projection (projection) portion 13a, so that the contact surface S that comes into contact with the first work 12 is small and the load is large. Therefore, the contact surface S efficiently generates resistance heat and is welded. Further, the resistance value Rs of the joint becomes larger than the contact resistance between the plus electrode 2 and the second work 13 and the contact resistance between the minus electrode 3 and the first work 12 when the joining state is poor. The quality of the joined state can be easily determined. In addition, the present invention
The present invention is not limited to the above embodiment, and may be implemented as follows.

(1) In this embodiment, the resistance welding apparatus is embodied as a resistance welding apparatus for projection welding. However, the invention is not limited to projection welding, but may be applied to another resistance welding machine such as a resistance welding apparatus for spot welding. It may be.

(2) In this embodiment, the resistance welding apparatus is a resistance welding apparatus in which the first work 12 and the second work 13 are pressed and welded on the upper surface of the fixed base 1.
The work 12 and the second work 13 may be embodied in a resistance welding apparatus such as holding and pressing the work 12 and the second work 13 in the plane of both electrodes.

(3) In the present embodiment, the first work 12 is made of steel and the second work 13 is made of an aluminum alloy. The material may be any material such as steel and brass as long as it can be resistance welded. Is also good.

[0031]

As described above in detail, according to the present invention, it is possible to reduce the time and labor required for inspecting the bonding state, and to inspect the bonding state without requiring a dedicated inspection device only for the inspection. , And has an excellent effect that unnecessary capital investment can be eliminated.

[Brief description of the drawings]

FIG. 1 is a principle explanatory diagram for explaining a resistance welding machine in an embodiment.

FIG. 2 is a conceptual waveform diagram illustrating a waveform when a bonding state is good.

FIG. 3 is a conceptual waveform diagram illustrating a waveform when a bonding state is poor.

[Explanation of symbols]

2 ... plus electrode, 3 ... minus electrode, 4 ... welding power supply device, 5 ... detection DC power supply device, 6 ... ammeter, 7 ... control device, 12 ... first work, 13 ... second work, 13a
... Protrusion, Vs: DC voltage for inspection, Is: Detection current value,
Rs: resistance value.

Claims (3)

[Claims] 1. A first electrode superposed from a first electrode (2).
An electric current is applied to the second electrode (3) through the work piece (12) and the second work piece (13) to make the work pieces (12, 1).
3), a test voltage (Vs) is applied between the two electrodes (2, 3), and both workpieces (2) and (3) are welded based on a current value (Is) flowing between the electrodes (2, 3). 12. A method for inspecting resistance welding, wherein the quality of a welding state between 12 and 13) is determined. 2. A second electrode (3) in press contact with a first workpiece (12), a first electrode (2) in press contact with a second workpiece (13), The first electrode (2) is connected to the second electrode (3) and is configured to supply a current for welding the first workpiece (12) and the second workpiece (13). A resistance welding apparatus provided with a first power supply device (4), wherein the first and second electrodes (2, 3) are connected to the first electrode (2) and the second electrode (3). A second power supply device (5) for supplying a test voltage (Vs) between the second power supply device and an ammeter (6) for measuring a current (Is) flowing through the circuit when the test voltage (Vs) is applied. ), After controlling the driving of the first power supply (4), controlling the driving of the second power supply (5) and driving the second power supply (5). When in the ammeter (6) resistance welding apparatus, characterized in that has a current value that is detected the control device for determining the quality of the weld on the basis of (Is) (7). 3. The resistance welding apparatus according to claim 2, wherein at least one of said first and second workpieces forms a projection (13a), and said projection (13a). ). A resistance welding apparatus characterized in that welding and inspection of a welding state are performed in a state of pressing.