JPS58179565A - Prevention method of welding distortion - Google Patents

Abstract

PURPOSE:To prevent easily the occurrence of welding distortion in welding one face of members to be welded, by heating a facing part of a welding point in the opposite face by the amount of heat which is nearly equal to heat input caused by welding. CONSTITUTION:When welding a horizontal member 7 to one side face of a vertical member 8 by a submerged arc welding machine 9, a coupling member 18 is connected to the welding machine 9, and the tip is extended to the opposite side of the welding face of the vertical member 8. A gas burner 19 is attached to a holding member 20 provided on the tip of the coupling member 18, and the tip of the burner 19 is directed to a point C on the opposite side face that faces a fillet welding point B of the vertical member 8 and the horizontal member 7. The horizontal member 7 is welded to the vertical member while moving the welding machine 9 mounted on a truck along the fillet weld zone. At the same time, the opposite side of the welding point of the vertical member 8 is heated by the burner 19 with the amount of heat nearly equal to heat input of welding. Bending of the vertical member 8 to the direction A due to distortion caused by one face welding can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing welding distortion that occurs when one side is automatically welded.

For example, when manufacturing a structural beam, which is often used for building beams, by welding a web and upper and lower flanges, the web 1 is placed horizontally and the flanges 2 are placed vertically on both sides of the web 1, as shown in Figure 1. Generally, they are brought into contact and tack-attached, the corner part 3 of -L is continuously welded, and the corner part on the back side is reversed and joined by fillet welding.

When one side of the plate member is welded in this way, heat enters the welded part of the base H and becomes high temperature, which shrinks when cooled.
In the example of FIG. 1, the flange 2 is distorted so as to fall inward in the direction indicated by arrow A in the figure.

In order to remove this distortion, conventionally, after welding, another worker would heat the back side of the welded part with a gas burner to gradually cool it down, and then return the distorted part to its original position, or use a large press to remove the distorted part. Since the distortion was removed by pressing, there was a drawback that the time required, manpower, and construction period were large.

As shown in Figure 2, there are also areas where single-sided fillet welding is performed, such as the welding part 6 between the deck 4 and side plate 5 of box girders, etc. of bridges, etc., and when it is large, the height is 3 m or more. This made it necessary to carry out strain relief work from the outside at a height of 3 m or more, and this work was extremely dangerous.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems regarding the removal of welding distortion associated with conventional one-sided fillet welding, it is an object of the present invention to provide a method that can prevent the occurrence of welding distortion with simple means.

Hereinafter, the present invention will be explained in detail based on examples thereof.

FIG. 3 is a diagram showing an example of an apparatus for carrying out the method of the present invention, and 7 in the figure is placed horizontally when welding, for example, the web of the above-mentioned structural beam or the deck of a box girder. This is the member that is used. Reference numeral 8 designates a member that is vertically disposed during welding, such as the flange of a ■-shaped beam or the side plate of a box girder. Reference numeral 9 denotes a known small automatic horizontal fillet submerged arc welding machine, in which a welding wire 111 wound around a bobbin 10 is used.
A Franks supply tank 12, a control panel 13, a wire feeding device 14, etc. are mounted on a 15vc cart, and the cart is moved toward a vertical member 8, which serves as a guide, by four oblique rubber tires 16, and the guide roller 17 is moved vertically. Continuous fillet welding is performed while traveling while abutting against the wall 8 and maintaining a predetermined distance from the weld line.

In the apparatus for carrying out the method of the present invention, a holding member 20 for holding a gas burner 19 is fixed to the bath welding machine 9Vc by a connecting member 18 beyond the upper part of the vertical member 8 to the above-mentioned welding machine. The position of the gas burner 19 can be adjusted in the vertical direction so that the vicinity of the point C on the back side of the fillet welding point B by the welding machine 9 can be heated. In the direction parallel to the welding line, there is no problem even if the positions of the welding point and the heating point are slightly shifted at the same time. The amount of heat input into the vicinity of point C of the member by the burner 19 is made to be equal to the amount of heat input into point B due to welding.

Since this device is constructed as described above, if the welding machine 9 is run to automatically perform continuous fillet welding and the burner is activated at the same time, the back side of the welding machine 9 will be automatically heated at the same time with the same amount of heat input. As the welding progresses, the amount of heat input on the front and back sides is equal, and almost no welding distortion occurs. Even if slight distortions are to be corrected by tapping after welding, much less work is required compared to conventional distortion removal VVC.

In the above embodiment, the horizontal fillet submerged arc welding machine was explained using the metal side, but the welding machine to which all the methods of the present invention can be applied is not limited to this, and any automatic welding machine is used (CC) It can also be applied to welding machines, etc.

As described above, the present invention allows a single welder to perform both welding and strain relief at the same time, whereas conventionally it was necessary for another worker to perform strain relief work after the completion of welding work. This reduces work man-hours and time required, and also contributes to improving safety by eliminating work at heights.

When manufacturing many products with the same dimensions, such as shaped beams, it is possible to improve efficiency by fixing the welding machine and the gas burner to prevent distortion, and moving all the workpieces at a constant speed in the direction of the weld line. Welding and distortion prevention can be performed. In this case, if there is a slight deviation between the welding position and the heating position by the burner, r1, the welding machine's start/stop switch will
It is convenient to use a timer to start and stop both the C welding machine and the gas burner at different timings.

[Brief explanation of the drawing]

FIGS. 1 and 2 are sectional views illustrating a fillet weld to which the method of the present invention is applied, and FIG. 3 is a perspective view showing an embodiment of an apparatus for carrying out the method of the present invention. 7.8... Part to be welded 9... Automatic welding machine 19.
...Gas burner B...Welding point C...Heating point Fig. 1

Claims (1)

[Claims] A method for preventing welding distortion, characterized in that when automatically welding one side of a member to be welded, the back side t is simultaneously heated so that the amount of heat input is equal to the amount of heat input due to welding.