JPS60121074A - Method of detecting end of weld line - Google Patents

Abstract

PURPOSE:To detect the end part of a weld line simply, accurately and in real time by setting a position where output voltage of a magnetic sensor attached to a welding torch that moves along the weld line as the end part of the weld line. CONSTITUTION:In a welding machine in which a welding torch 3 made movable perpendicularly to a base metal 1 by a driving shaft 6 and a driving motor 7 is mounted on a welding truck 2 that is moved on the base metal 1 by a motor 5 and moved in the direction of welding, a magnetic sensor 4 is attached to above- mentioned welding torch 3 to keep a specified distance from the base metal 1 and the output voltage is detected and outputted to a controlling device 8. The end part of the weld line is detected at a place where the output voltage exceeds a threshold value set beforehand experimentally, and the motor 5 for running the truck and welding power source 9 are stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting weld line ends when welding structures.

Currently, various types of structures are welded using manual welding, gravity welding, typically covered arc welding, semi-automatic welding, in which only the welding wire is fed automatically, and automatic welding, in which welding equipment is mounted on a trolley and runs. ,ing.

Recently, welding robots have been introduced from the viewpoint of labor saving and manpower saving, but in this case, welding robots can of course be used to imitate welding lines.
In order to start and stop the welding arc, it is necessary to detect the end position of the member.

Among these methods, the arc sensor method that detects changes in welding electrical work, or the mechanical method that uses rollers, etc., is used to trace the welding line. , a teaching playback method in which the end position is taught, or a method in which the shape and dimensions of the member are converted into NC information and the start and end positions are set using this information are often used.

However, the teaching playback method requires a large amount of time for teaching work. Furthermore, the edge setting method based on NO information has the disadvantage that accurate edge detection cannot be performed if there is a mounting error in the component or deformation of the base material during welding.

Therefore, the present inventors conducted research to solve this problem, and as a result, they focused on magnetic sensors. That is, as shown in FIG. 1, the magnetic sensor output voltage is between l! and the base material. J.G.
Since the height changes in proportion to the height of the magnetic sensor, it is usually used to control the height between the base material and the device to which the magnetic sensor is attached. The present inventors have discovered that even if the gap between the magnetic sensor and the base metal remains constant, the output of the magnetic sensor changes almost proportionally depending on the distance between the edge of the base metal and the magnetic sensor. .

The present invention has been made based on this knowledge, and its purpose is to utilize the output characteristics different from the steady state that occurs when the magnetic sensor approaches the end of the workpiece to detect welding deformation or It is an object of the present invention to provide a weld line end detection method that is capable of detecting the end of a welded part without being affected by mounting errors of members, etc., and without requiring teaching work before welding.

That is, in the present invention, the welding torch is moved in the direction of the welding line, the output voltage of a magnetic sensor attached to the welding torch is detected from the left, and the point where this output voltage exceeds a predetermined threshold is determined as the end of the welding line. It is characterized by

The present invention will be described below with reference to illustrative embodiments.

FIG. 2 shows a welding device capable of detecting weld line ends. In this device, a welding torch 3 is added to a welding cart 2 that moves over a base material 1, and a magnetic sensor 4 is attached to the welding torch 3. direction. Further, the welding torch 3 is moved perpendicularly to the base material 1 by a drive@6 and a drive motor 7.

Furthermore, the magnetic sensor 4 is provided so as to maintain a certain distance from the base material 1, and its output voltage is connected to a control device 8 shown in FIG. 3. Control device 8 controls welding power source 9 using the control signal.

In this apparatus, as shown in FIG. 1, first, the magnetic sensor 4 is operated as a normal copying (position control) function in the middle part of the base material (between X) where regular welding is performed. Of course, the welding line may be copied using another method such as a copying roller method or an arc sensor method, and only the torch height may be controlled using the magnetic sensor 4. In this case, as in the conventional case, the drive @6 is moved by the motor 5 according to the change in the distance between the welding torch 3 and the base material 1, that is, the distance G between the magnetic sensor 4 and the base material I.
The gap between the magnetic sensor 4 in solution and the base material 1 is set to a nearly constant value G1.
control to keep it at that level.

Therefore, the output voltage of the magnetic sensor 4 is a constant value S1 corresponding to the gap G1 between the magnetic sensor 4 and the base material 1.

However, as welding progresses, the magnetic sensor 4
K near the end of (actually (d) 20~30 N7
1), even though the gap G1 between the magnetic sensor 4 and the base material 1 is kept constant, the output of the magnetic sensor exhibits characteristics as shown in FIG.

In this invention, when the magnetic sensor 4 comes to the vicinity K of the base material end, the level control program is switched to the end detection program. In other words, the distance control between the magnetic sensor 4 and the base material l based on the magnetic sensor output signal is discontinued, and the end portion is detected by detecting the voltage of the preset threshold value 82 (''). In this case, the threshold value is determined by testing in advance.
Settings are made in step 17 based on this test data. Also, switching from the position control program to the edge detection program is as follows:
All you need to do is to determine the approximate location in advance with some help.

When the output voltage of the magnetic sensor 4 reaches the threshold value, the control device 8 stops the cart treading motor 5 and the welding power source 9. Automatic welding can be performed in this way.

Next, other embodiments of the present invention will be described.

Figures 5 and 6 show the application of the method of the present invention to weld line tracing for horizontal fillet welding. In this case, welding torch 3
and two magnetic sensors 41.

4□ is attached so that each magnetic sensor 41r42 maintains a certain gap with the flat plate 10 and lip plate 11, respectively. And these magnetic sensors 4, . By detecting the end of the riff plate 11 on the flat plate 10 at 42, it is possible to carry out termination processing of the weld bead, such as corner welding, as shown in FIG. 6, for example.

In the present invention, it goes without saying that the welding starting point, that is, the end of the base material at which welding should start can also be detected in a similar manner.

As explained above, according to the present invention, teaching work is not required compared to the teaching playback method or the base material end setting method using NC information, and furthermore, deformation during welding or attachment of parts is affected by errors. This has the remarkable effect of being able to perform edge detection in real time while welding is in progress.

[Brief explanation of drawings]

Fig. 1 is a characteristic diagram showing changes in the magnetic sensor output depending on the distance between the magnetic sensor base materials, Fig. 2 is an explanatory diagram showing an example of a welding device used in the method of the present invention, Fig. 3 is a block diagram of the same, and Fig. 4
FIG. 5 is an explanatory view showing another embodiment of the method of the present invention, and FIG. 6 is a perspective view showing a welding result by the same method. DESCRIPTION OF SYMBOLS 1... Base material, 2... Welding trolley, 3... Welding torch, 4... Magnetic sensor, 5... Motor, 6... Drive shaft, 7... Drive motor, 8... ...control device, 9...
Welding power source, 10... Flat plate, IZ... Ribbed plate - Applicant's sub-agent Patent attorney Takehiko Suzue Continuation of page 1 0 Inventor Satoshi Urakawa Kannonsaku Hiroshima Shipyard, Nishi-ku, Hiroshima City 0 shots Author: Tamotsu Oka Kannonsaku Hiroshima Research Institute, Nishi-ku, Hiroshima City - 0A

Claims (1)

[Claims] It is characterized by detecting the output voltage of a magnetic sensor attached to the welding torch while moving the welding torch in the welding line direction, and determining the point where the output voltage exceeds a predetermined threshold as the welding line end. A method for detecting the edge of a weld line.