JPH05318116A - Method for detecting abnormality at time of welding - Google Patents

Abstract

PURPOSE:To improve productivity by detecting welding defects simultaneously with welding, specifying the places and eliminating a conventional helium test. CONSTITUTION:At the time of welding, a melting crucible 6 is immediately imaged by a camera 5, and the contour 6a of the melting crucible 6 with the image picked up is displayed in a monitor 10 together with a first detection frame 12 and a second detection frame 13. If the contour 6a is smaller than the first detection frame 12 and larger than the second detection frame 13, welding is normal. If a part of the contour 6a is smaller than the second detection frame 13 or larger than the first detection frame 12, abnormality in the welding is detected and the signal 14 is outputted. Thus, welding defects are detected simultaneously with welding, and the place of defect is specified. In the case where welding defects are caused continuously, the welding may be suspended through the feedback of the signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detection method for welding, which detects an abnormality during welding of a metal material by non-electrolytic electrode type inert gas arc welding.

[0002]

2. Description of the Related Art Conventionally, a welded portion of a metal material which constitutes a vacuum container requires airtight welding over the entire welding line.
In particular, when a thin stainless steel plate is used as the metal material, it is common to use non-welding electrode inert gas arc welding, for example, TIG welding, as the welding method.
After the welding is completed, all lines are airtightly tested (helium inspection) using a helium leak detector.

Further, as a method for detecting defects in a welded portion at the same time as welding, there is provided a method for inspecting a laser welded portion as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-255288. In this conventional method, when welding a butt portion of a thin steel plate by using laser light, defective fusion of the butt portion is detected based on an output from a temperature sensor provided at the tip of a nozzle for irradiating the laser light. is doing.

[0004]

However, according to the inspection method of performing the airtightness test using the above-mentioned conventional helium leak detector, the productivity is remarkably low. Further, the conventional inspection method disclosed in Japanese Patent Laid-Open No. 2-255288 only automatically determines whether or not there is a melt-in defect at the butt portion, and cannot detect a weld defect in hermetic welding.

An object of the present invention is to provide a method for detecting abnormalities during welding, which can detect welding defects in airtight welding simultaneously with welding.

[0006]

In order to achieve the above object, an abnormality detecting method for welding according to the present invention is a camera connected to a welding torch side when welding a metal material by non-electrolytic electrode type inert gas arc welding. The contour of the image of the molten pool taken in step 1 is displayed on the monitor together with the first detection frame that is larger than the preset normal contour of the molten pool and the second detection frame that is smaller than that of the normal contour of the molten pool. When it is larger than the detection frame or smaller than the second detection frame, the signal is output.

[0007]

According to the structure of the present invention, when the desired welding is performed while moving the welding torch along the welding line, the molten pool can be immediately imaged by the camera, and the contour of the imaged molten pool can be obtained. Can be displayed on the monitor together with the first detection frame and the second detection frame. At this time, when the contour is smaller than the first detection frame and larger than the second detection frame, welding is normal.

When a part of the contour is smaller than the second detection frame and a part of the contour is larger than the first detection frame, it is possible to detect that the welding is abnormal and to output a signal. Become. This makes it possible to detect a welding defect at the same time as welding and specify a location, and when a defective welding portion continues, a signal can be fed back to stop the welding.

[0009]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 and FIG. 2, 1A and 1B are welding base materials made of a thin plate of stainless steel (an example of a metal material), and side faces thereof are considerably contacted to each other to form a butt welding line 2. 3 is a metal fitting for a dolly,
A welding torch 4 is attached with its lower end inclined with the movement direction. Here, as the welding, non-electrolytic electrode type inert gas arc welding is adopted. A camera 5 is attached to the fitting 3 in front of the welding torch 4, and the camera 5 is arranged so as to face the molten pool 6 with its lower end inclined toward the rear direction. 7 indicates a weld bead.

In FIG. 3, reference numeral 10 is a monitor, which is connected to the camera 5 through an image recognition device 11, and the screen shows
The contour 6a of the image of the molten pool 6 captured by the camera 5 has a first detection frame 12 that is larger than the preset contour of the normal molten pool and a second detection frame 13 that is smaller than the contour of the normal molten pool.
Is displayed together with.

Here, the size of the first detection frame 12 is a size corresponding to the maximum value of the size of the molten pool 6 allowed,
The size of the second detection frame 13 corresponds to the minimum allowable size of the molten pool 6. The sizes of the first detection frame 12 and the second detection frame 13 are uniquely determined by the material of the welding base material, the plate thickness, the joint shape, the welding current, the welding speed, and the welding torch angle.

The welding operation in the above embodiment will be described below. In order to perform airtight welding of a thin stainless steel plate by TIG welding, the molten pool 6 is made to precede the welding torch 4, and the welding line 2 is melted in the molten pool 6 instead of in the arc (welding current, welding speed, welding torch). Weld at different angles. At that time, the molten pool 6 is made of the material of the welding base materials 1A and 1B,
When the conditions of plate thickness, joint shape, welding current, welding speed, and welding torch angle are fixed, the size is constant everywhere on the welding line 2, but there is a gap in the welding line 2, misalignment, or rising If there is a material defect, the molten pool 6 will be interrupted, distorted, or the size will change.

It has been found that defective welding occurs in a portion where the size of the molten pool 6 is changed, and the present invention is based on this finding. According to the above example,
When the desired welding is being performed while moving the welding torch 4 along the welding line 2, the molten pool 6 immediately moves to the camera 5
Is imaged. The imaged image of the molten pool 6 is passed through the image recognition device 11, and the outline 6a of the image is the first detection frame.
It is displayed on the monitor 10 together with 12 and the second detection frame 13.

As shown in FIG. 3, when the contour 6a of the molten pool 6 is smaller than the first detection frame 12 and larger than the second detection frame 13, welding is normal and a signal is output from the image recognition device 11. do not do. Then, as shown in FIG. 4, when the contour 6a of the molten pool 6 is smaller than the first detection frame 12 and partly smaller than the second detection frame 13, it is detected that welding is abnormal (welding failure). Then, the image recognition device 11 outputs the signal 14. Further, as shown in FIG. 5, when even a part of the contour 6a of the molten pool 6 is larger than the first detection frame 12 and larger than the second detection frame 13, it can be detected that welding is abnormal, and image recognition is performed. A signal 14 is output from the device 11.

Abnormalities in welding can be detected by the output of the above-mentioned signal 14, and in this case, the alarm mark is monitored by issuing an alarm by the output of the signal 14 or by the output of the signal 14.
By displaying on 10, the operator can be made to identify and recognize the location of the welding abnormality. In addition, the output of signal 14 is the image recognition device.
By storing it in 11 or the like, it is possible to specify the location where the welding is abnormal at a later time by the screen display or punching. Further, when the defective welding portions continue, it is possible to stop the welding by feeding back a signal.

When the first detection frame 12 and the second detection frame 13 are stored in the image recognition device 11, the image recognition device 11
The contour 6a can be displayed on the monitor 10 together with the images of the first detection frame 12 and the second detection frame 13. When the first detection frame 12 and the second detection frame 13 are displayed in advance on the monitor 10 by printing, etc., the first detection frame 12 and the second detection frame 12 are displayed.
The outline 6a or the like can be displayed by being superimposed on the detection frame 13.

The non-electrolytic electrode type inert gas arc welding is TI
In addition to G welding, plasma arc welding is also applicable and applicable. The metal material (welding base materials 1A and 1B) is not limited to stainless steel, but can be applied to mild steel, low alloy steel, and aluminum.

[0018]

According to the present invention having the above-mentioned structure, when the desired welding is performed through the welding torch, the molten pool can be immediately imaged by the camera, and the imaged contour of the molten pool can be obtained.
It can be displayed on the monitor together with the first detection frame and the second detection frame. At this time, when a part of the contour is smaller than the second detection frame, and when a part of the contour is larger than the first detection frame, it is possible to detect that welding is abnormal and output a signal.

With this, since it is possible to detect the welding defect and to specify the location at the same time as the welding, the conventional helium inspection becomes unnecessary and the productivity can be improved. When the defective welding parts are continuous, it is possible to feed back a signal to stop the welding and reduce defective welding.

[Brief description of drawings]

FIG. 1 is a front view of a welded portion showing an embodiment of the present invention.

FIG. 2 is a side view of the welded portion.

FIG. 3 is a monitor screen diagram in the normal state.

FIG. 4 is a monitor screen diagram when the molten pool is small and defective.

FIG. 5 is a monitor screen view when the molten pool is large and defective.

[Explanation of symbols]

 1A Welding base metal (metal material) 1B Welding base metal (metal material) 2 Welding line 3 Mounting bracket 4 Welding torch 5 Camera 6 Weld pool 6a Weld pool contour 10 Monitor 11 Image recognition device 12 First detection frame 13 Second detection frame 14 signals

Claims (1)

[Claims] 1. When welding a metal material by non-welding electrode inert gas arc welding, the contour of the image of the molten pool taken by a camera connected to the welding torch side is used to set the contour of a normal molten pool which is set in advance. It is displayed on the monitor together with the first detection frame that is larger than the contour and the second detection frame that is smaller than the contour, and a signal is output when a part of the contour of the molten pool is larger than the first detection frame or smaller than the second detection frame. Characteristic welding abnormality detection method.