JP2548069Y2 - Pass / fail judgment of spot welds - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for judging the quality of a spot weld, and more particularly, to the structure of a detector for judging the quality.

[0002]

2. Description of the Related Art As is well known, a sheet metal component is joined by spot welding, and a nugget is formed inside the joined portion to determine whether the device has sufficient peeling resistance. There is a structure shown in FIG. In other words, the structure shown in FIG. 3 is based on a structure that detects the residual stress at the welded portion by the Barkhausen effect generated when changing the magnetization of the magnetic material. Specifically, the structure shown in FIG. Probes A each having an exciting part A1 provided with an exciting coil and a detector A2 located between the exciting parts A1
And a welding quality tester B to which the result of the stress measuring device B1 electrically connected to the probe A is inputted.
The exciter A1 and the detector A2 in the probe A described above are arranged such that the tips facing the welded portion are located on the same plane so that they can simultaneously contact the surface of the welded portion.

Further, the above-described probe A is provided with a positioning member C having a plunger C1 which is urged against the welding location. The plunger C1 is formed on the surface of the welding location. An optimal position for detecting a stress value detected by the detector A2 is positioned with respect to a position of a nugget which is abutted against a certain indentation and is assumed to be generated inside an indentation generated at a welding location. It has become.

In the welding quality judging device having such a structure, an alternating current is applied to the coil of the exciting unit A1 so that the exciting unit A
1 is magnetized by alternating current, and the noise generated by the movement of the domain wall of the crystal grains of the metal inside the welded portion during the magnetization, that is, the Barkhausen effect noise generated when the magnetization of the magnetic material is changed is pulled. The quality of welding is determined by judging that the weld strength increases and the compressive stress decreases. The specific state of such a judgment is that when welding is performed well and a nugget is generated inside the indentation, the tensile stress is large at the welding point, and the compressive stress is large around the welding point. , The compressive stress gradually decreases with increasing distance from the indentation, and finally the residual stress becomes “0”. If the welding is not complete and a nugget is formed, the tensile stress and the compressive stress are small, and the residual stress is close to “0”. Therefore, since the welding state of the spot welded portion and the residual stress are closely related, the quality of the welding can be determined by detecting the residual stress.

[0005]

However, in the welding quality judgment apparatus having the above-described structure, since the exciting section A1 and the detector A2 are integrally combined as a probe A, for example, When the portion is on a curved surface, the adhesion between the tip of the exciting portion A1 and the surface of the welded portion may be deteriorated. In this case, the current for obtaining a current corresponding to the residual stress taken into the detector A2 may be obtained. It is difficult to form a constant AC magnetic field, an error occurs in the current detected by the detector A2, and it may not be possible to properly determine the quality of the welding state.

Accordingly, an object of the present invention is to secure the adhesion between the exciting portion and the surface of the welding portion, and particularly to ensure the adhesion on a curved surface, in view of the above-mentioned problems in the conventional welding quality determination device. It is another object of the present invention to provide a welding quality determination device having a structure capable of accurately determining the quality of a welding state by improving the adhesion even at the contact position of the detector.

[0007]

According to the present invention, a probe having an exciting portion and a detector is brought into contact with the surface of a welding portion, and a magnetic material is formed by forming a magnetic field from the exciting portion. In the apparatus for judging pass / fail of a spot weld by detecting residual stress according to a nugget formation state of the welded spot by Barkhausen effect noise generated in a difference that changes the magnetization of the excitation section and the detection of the excitation section, And an exciting coil forming the exciting unit is provided on the surface of the welding component gripping part of the spot welding machine, and the detector can be arranged at a predetermined detection position independently of the exciting unit. It is characterized by having a structure.

[0008]

According to the present invention, the exciting portion is in close contact with the surface of the welded portion by using the welding part gripping portion used for welding the welded part, and the detector is connected to the exciting portion. Independently placed at the weld.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows a main part of a pass / fail determination device according to an embodiment of the present invention.
The excitation unit 2A and the detector 2B
The above-described excitation unit 2A is constructed by embedding an excitation coil in the surface of a clamp 3 serving as a welding part gripping part provided in a spot welding machine. .

On the other hand, the detector 2B is connected to a welding quality judging device 4 including a stress measuring device in the same manner as in the prior art, but from the judging device 4 via a connection code 4A. It is configured such that the operator can hold and move to an arbitrary position on the surface of the sheet metal part 5 which is the inspection object.

Since the present embodiment has the above structure,
The sheet metal part 5 to be inspected is disposed between the clamp 3 of the spot welding machine and the locator 6 facing the same as shown in FIG. In this state, when the surface of the sheet metal part 5 is clamped by the clamp 3 and the locator 6 by an elevating device (not shown), the exciting portion 2A comes into close contact with the surface of the welding portion while being pressed. On the other hand, the detector 2B is a nugget (see FIG.
In this state, the excitation coil is energized to detect residual stress due to Barkhausen effect noise.

According to the present embodiment, the detector 2B is
A can be arranged at an arbitrary position independently of A, so that the size can be set without being affected by the size of the exciting unit 2A. By reducing the size of the needle, the contact area with the surface of the welding location can be reduced, thereby improving the adhesion.

[0014]

As described above, according to the present invention, the exciting part and the detector are separate members, and the exciting part is provided on the welding part gripping part used for bringing the welding parts into close contact during spot welding. Therefore, good adhesion to the surface of the welded portion is obtained. Therefore, since the magnetization by the excitation unit can be surely and fixed, the residual stress in the welded portion can be accurately detected.

Further, according to the present invention, since the above-mentioned excitation unit uses the welding part gripping part of the spot welder, even if the quality of the welding at the curved surface part is to be determined, the quality of the welding is good. By arranging the welding part gripper at an appropriate position and bringing the excitation unit into close contact with the surface, the above-described magnetization can be reliably performed, so that regardless of the state of the part to be inspected, a constant excitation characteristic is always maintained. Can be set.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a main part of an apparatus for determining the quality of a spot weld according to an embodiment of the present invention.

FIG. 2 is a view in the direction of the arrow shown in FIG.

FIG. 3 is a schematic diagram for explaining a conventional structure of a pass / fail determination device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pass / fail judgment apparatus 2 Probe 2A Exciting part 2B Detector 3 Clamp which forms a part of welding part gripping part 4 Connection code 5 Sheet metal part which is a part to be inspected 6 Location which forms part of welding part gripping part Ta

Claims (1)

(57) [Scope of request for utility model registration] A probe having an exciting section and a detector is brought into contact with the surface of a welding portion, and the Barkhausen effect noise generated when the magnetization of the magnetic body is changed by the formation of a magnetic field from the exciting section causes the noise. In an apparatus for judging pass / fail of a spot weld by detecting residual stress in accordance with a state of formation of a nugget at a welding portion, the excitation coil and the detector are separated from each other, and an excitation coil forming the excitation section is a spot. A spot welding part which is provided on a surface of a welding part holding part of the welding machine, and wherein the detector is arranged at a predetermined detection position independently of the excitation part. Judgment device.