JPH0360882A - Method for deciding quality of welding state - Google Patents

Abstract

PURPOSE:To accurately decide the quality of a welding state by cooling materials to be welded, then, heating locally a weld zone of the materials to be welded, measuring a temperature distribution in the vicinity of the weld zone by an infrared temperature detector and deciding the quality of the welding state from the measured temperature distribution. CONSTITUTION:The materials to be welded are composed of two plates W1 and W2 and ends of both plates are superposed on each other and irradiated twice with a laser beam to form beads B1 and B2. After welding is completed, the materials to be welded are once cooled and then, the weld zone is heated by using heating equipment 1. A heater 3 is heated by a heating wire 2 and abutted on between both beads and the upper side plate W1 is heated locally. When it is heated to the specified temperature, the heating equipment 1 is removed and the temperature distribution of the weld zone is detected by the infrared temperature detector 4. A monitor 5 is connected with the infrared temperature detector 4 and temperature distribution of the above- mentioned materials can be seen with the eyes as an image. This temperature distribution is compared with that of a superior product or an inferior product to decide the quality of the weld zone. By this method, there is no influence by the adjacent weld zone and accurate decision can be made.

Description

Detailed Description of the Invention A8 Purpose of the Invention (1) Industrial Application Field The present invention is a method for determining the quality of welding of a polymerized and welded workpiece based on the intensity of infrared rays emitted from the welded part. The present invention relates to a method for making a determination based on the present invention.

(2) Conventional technology Conventionally, as a method for determining the quality of welding conditions,
The one described in Japanese Patent No. 0-79378 is known.

The above method uses an infrared temperature detector to detect infrared rays emitted from the welded part of the workpiece, which is in a high temperature state immediately after welding is completed, to measure the temperature distribution of the welded part, and based on the results, the welding state is determined. It is designed to judge the quality of the product.

(3) Problems to be Solved by the Invention However, in the above-mentioned conventional method, when multiple parts of the workpiece that are close to each other are successively welded, it is difficult to detect infrared rays emitted from the welded part immediately after welding. Since welding work on other adjacent parts is performed in parallel, there is a problem in that the detection accuracy of the infrared temperature detector is reduced due to the influence of infrared rays generated by the welding work. For this reason, when welding objects to be welded, even if the welding condition of both objects is poor, it may be determined that the welding condition is good due to the influence of infrared rays emitted from other parts.

The present invention was made in view of the above-mentioned circumstances, and accurately detects the intensity of infrared rays by eliminating the thermal influence of other welds, thereby reliably determining whether the welding condition of the weld is good or bad. The purpose is to provide a method that makes it possible.

B1 Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a method for determining the quality of welding of a welded object that has been polymerized and welded after completion of welding. The determination method includes a step of cooling the workpiece after welding is completed, a step of locally heating the welding part of the workpiece, and measuring the temperature distribution near the welding part with an infrared temperature detector. and a step of determining the quality of the welding condition from the measured temperature distribution.

(2) Effects According to the above-described present invention, after the welding work has been completed, the welded object is once cooled, and then only the welded portion to be inspected is locally heated. Next, the temperature distribution in the vicinity of the welded area is measured by detecting infrared rays emitted from the heated welded area using an infrared temperature detector. Subsequently, the quality of the welded portion is determined by comparing the measured temperature distribution with the temperature distribution of a non-defective product or the temperature distribution of a defective product. At this time, the workpiece is cooled once after welding is completed, and then only the welded part to be inspected is locally heated to measure the temperature distribution, so infrared rays from other parts can cause detection errors. No radiation is emitted, making it possible to accurately determine the welding state.

(3) Examples Hereinafter, the present invention will be described in detail based on the drawings.

Figures 1 to 4 show one embodiment of the present invention.
Figure 2 shows the process of heating the welded part, Figure 2 shows the process of measuring the temperature distribution of the welded part, Figure 3 shows the shape of the workpiece, and Figure 4 shows the temperature distribution of the welded part. Figure 2 is a graph showing an example.

As shown in Figure 3, the objects to be welded are two plates W1 and W2.
The edges of both plates W, , W are overlapped with each other with a predetermined joining width and are welded by continuous welding using a laser beam. Welding is performed by irradiating the laser beam twice at a predetermined time interval, the first bead B1 is irradiated with the laser beam twice, and the second bead B1 is irradiated with the second bead B1 with the second irradiation.
2 is formed. Each bead B, B2 is formed into two short parallel lines by moving the irradiating laser beam.

After the welding is completed, the object to be welded is once cooled, and then, as shown in FIG. 1, the welded part is heated using a heating device 1. That is, the heating device 1 includes a heater 3 that receives heat from the heating wire 2 and is maintained at a high temperature, and this heater 3 is connected to both beads B1. The upper plate material W1 is locally heated by bringing it into contact between B2.

Welded part of plate material W1, that is, both parallel beads B1.82
When the space is heated to a predetermined temperature, the heating device 1 is removed,
As shown in FIG. 2, the temperature distribution of the weld zone is detected by an infrared temperature detector 4 such as a well-known thermograph.

The infrared temperature detector 4 detects the intensity of infrared rays emitted from the surface of an object according to its temperature, and outputs the temperature distribution of the object as an image signal by amplifying and calculating the results. A monitor 5 is connected to the infrared temperature detector 4, so that the temperature distribution of the object can be directly viewed as an image.

FIGS. 4(a) to 4(d) show the two-dimensional temperature distribution on the surface of the upper plate material W1 at the welding part of the workpiece measured by the infrared temperature detector 4, and its P-P One-dimensional temperature distribution p in the line or Q-Q line cross section,
It shows q.

FIG. 3(a) shows the state of a normal weld zone, where a sudden change in temperature is observed in the vicinity of surface weld beads B, B2, and a sudden drop in temperature in the area outside of these beads. This is because the weld bead B, B2 is completely welded to the upper and lower plates W,
, W, this weld bead B, ,B
2, heat is rapidly transferred from the upper plate material W1 to the lower plate material W2, and the temperature of the upper plate material WI increases to the welding bead B.
This is because it decreases near .

Figure 3(b) shows the temperature distribution when there is a welding defect in the second bead B. Although there is a rapid temperature drop near the normal first bead B1, as described above, On the other hand, in the defective welding area (on the right side), the temperature decreases more slowly. This is because the second
Since the bead B2 does not sufficiently penetrate from the upper plate Wl to the lower plate W, heat cannot escape from the upper plate W to the lower plate W2, and as a result, the second bead B
This is because a sudden temperature drop does not occur in the vicinity of 2.

FIG. 3(c) shows the temperature distribution when the welding state differs depending on the position of the weld beads Bl and B2. That is, P-P corresponding to the upper part of weld bead B, B2
In the temperature distribution p (shown by the solid line) in the line cross section, the temperature change in the second bead B2 is gradual, indicating that there is a welding defect in this portion. On the other hand, in the temperature distribution q (shown by the broken line) in the Q-Q line cross section corresponding to the lower part of weld beads B, B2, the temperature change in the first bead B1 is gradual, and there is a welding defect in this part. It shows that there is.

Figure 3(d) shows the temperature distribution when there is a welding defect in which both weld beads B, B2 do not fully reach the lower plate material W. In this case, the temperature distribution is shown from the upper plate material W1 to Since heat is transferred slowly to the side plate material W mainly through its contact surface, the temperature decrease in the vicinity of the surface weld beads B, B, is gradual.

As described above, when the quality of the weld is judged from the measured temperature distribution of the weld, the heated weld is cooled again, and then the next weld is locally heated to check the weld state. A pass/fail judgment is made. At that time, since the heating for inspection is at a low temperature, the cooling is performed quickly.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various small design changes can be made without departing from the scope of the invention described in the claims. Is possible.

For example, instead of displaying the temperature distribution of the weld on a monitor, it may be recorded on a graphic recorder.

In addition, temperature distribution patterns corresponding to various welding defects are stored in advance in the computer, and by comparing the measured temperature distribution with the stored temperature distribution, the quality of the welding condition is automatically determined. You can. Also,
The means for heating the welded part is not limited to those in the embodiments, and heating by radiant heat or heating by hot air can be used. In this case, it is also possible to heat the welded part and measure the temperature distribution in parallel. be.

C1 Effect of the Invention According to the above-mentioned invention, after the welding work is completed, the workpiece is cooled down, and then only the predetermined welded part is locally heated and its temperature distribution is determined from the infrared rays emitted. Therefore, even when a plurality of welds are arranged adjacent to each other, the detection accuracy of the infrared temperature detector will not be adversely affected by the thermal influence from the adjacent welds. Therefore, an accurate correlation can be obtained between the temperature distribution of the welded part and the welding condition, and it becomes possible to accurately determine whether the welding condition is good or bad.

[Brief explanation of drawings]

Figures 1 to 4 show one embodiment of the present invention.
Figure 2 shows the process of heating the welded part, Figure 2 shows the process of measuring the temperature distribution of the welded part, Figure 3 shows the shape of the workpiece, and Figure 4 shows the temperature distribution of the welded part. Figure 2 is a graph showing an example. w,, W2... Plate material (object to be welded) 4. Infrared temperature detector patent applicant Honda Motor Co., Ltd.

Claims (1)

[Scope of Claims] A method for determining the quality of welding of a welded object that has been polymerized and welded after welding is completed, comprising: cooling the welded object after welding is completed; It consists of a step of locally heating the welding part of the workpiece, a step of measuring the temperature distribution near the welding part with an infrared temperature detector, and a step of determining the quality of the welding state from the measured temperature distribution, Method for determining the quality of welding.