JPH1080765A - Welding method, and its equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the residual stress in a weld zone by performing the welding with each end of a material to be welded in a restricted condition while the oscillation is given thereto. SOLUTION: Each end of materials 1, 1 is welded in a restricted manner in a hollow part 2a of a restrictive jig 2 of hollow rectangular parallelopiped shape. The restrictive jig 2 is oscillated while a part 8 to be welded of the material 1 is welded. The molten metal at the part 8 to be welded is stirred by the oscillation, and the gas such as hydrogen which may cause blow holes is emitted. Adhesion of scattering spatters to material 1 is prevented by the oscillation. Because the part 8 to be welded is solidified while it is plastically deformed under oscillation, the residual stress and welding distortion can be reduced. The acceleration and amplitude of the oscillation of the part 8 to be welded are detected by an oscillation detector 18, and a control device controls the moving speed of a welding torch and the delivering speed of a wire for welding so that the welding is appropriate. Slag of the part 8 to be welded is naturally separated by the oscillation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for welding steel structures such as ships and bridges.

[0002]

In a welded joint of a steel structure such as a ship or a bridge, excessive residual tension near the yield point of a welded material at and around a welded portion due to shrinkage in a process of solidifying a molten metal. The occurrence of stress and welding distortion is often observed.

[0003] Such residual stress and welding strain induce fatigue, vesicular fracture, stress corrosion cracking, and the like of the welded joint. However, the removal and reduction thereof are conventionally performed by heat treatment such as stress relief annealing or fatigue. In order to increase the strength, means for performing shot peening immediately after welding is provided.

The conventional means for reducing residual stress by heat treatment such as stress relief annealing requires not only large-scale welding equipment corresponding to the size of the material to be welded, but also the end of welding. Since the heat treatment is performed later, there is a problem that the working time is long and the welding cost is high.

[0005] In recent years, with the aging of welding workers and the shortage of personnel, the spread of welding robots has made it necessary for one worker to operate a plurality of welding robots and automatic welding machines. However, accompanying this, a large amount of labor and time are required for removing slag and spatter generated during welding.

In view of the above-mentioned problems, the present invention suppresses residual stress in a welded portion almost simultaneously with welding, reduces the adhesion of spatter at the time of welding, and promotes rapid peeling of slag to accompany welding. An object of the present invention is to provide a method and an apparatus for welding a structure capable of reducing incidental work.

[Means for Solving the Problems]

According to the present invention, in order to solve the above-mentioned problems, when an arc is generated between opposed workpieces and the workpiece is welded, both ends of the workpiece are restrained so as to be welded. Welding while applying vibration to a part, more specifically, for example, in butt welding of a flat plate supported at the periphery, adding a vibration stress to a part where a non-welded part is melting and solidifying by a vibrator, and We propose a welding method characterized by plastic deformation.

[0008] Further, as an apparatus for carrying out the welding method, a restraining jig for supporting opposite ends of a workpiece to be welded in a restrained state, a welding torch for generating an arc in a welded portion, A vibration device for applying vibration to the welded portion via a jig is provided.

According to this invention, both ends of the material to be welded are supported by the restraining jig in a restrained state, the welded portions are butted, and vibration of a predetermined frequency and amplitude is applied by the vibrating device via the restraining jig. While applying to the to-be-welded part, an arc is generated in the to-be-welded part by a welding torch.

The arc melts the welded portion to form a weld metal, and the molten metal is agitated by the vibration, thereby promoting the release of a gas such as hydrogen causing blowholes in the welded portion. At the same time, the spatter that is scattered is prevented from adhering to the material to be welded.

Further, since the welded portion is vibrating, the molten metal and the vicinity thereof solidify while being plastically deformed, thereby suppressing the occurrence of residual stress and welding distortion.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a front external view of a welding apparatus for carrying out a method for welding a structure according to an embodiment of the present invention, and FIG.
Shows perspective views of the workpiece and the restraining jig, respectively. In FIG. 1, reference numeral 9 denotes a pair of rail supports erected on a foundation 100, 10 denotes a rail erected horizontally on the rail support 9, and 12 denotes a rail mounted on the rail 10 so as to run. The bogie 11 is a welding torch held by the bogie 12.
Reference numeral 3 denotes a conduit cable connected to the torch 11.

Reference numeral 15 denotes a nozzle attached to the tip of the torch 11. A welding wire 14 is continuously fed to the nozzle 15 via the conduit cable 13, and the material 1 to be welded (see FIG. 2) ) Is to be welded. The carriage 12 is provided with a height adjusting jig 16 for setting the distance between the workpiece 1 and the nozzle 15 and a handle 17 for operating the jig 16.

Reference numeral 5 denotes a main body of the electromagnetic vibrating apparatus, and 6 denotes a vibrator mounted on the main body 5. A table 7 is mounted on the vibrator 6, and on the table 7, The restraining jig 2 is fixed by bolts (not shown) inserted into the plurality of bolt holes 4. As shown in FIG. 2, the constraining jig 2 is formed in a hollow rectangular parallelepiped shape, and the workpieces 1, 1 having a V-shaped groove formed in a rectangular hollow portion 2a are formed at both ends. Is restrained welding 3.

The embodiment shown in FIG. 2 shows a case where a copper plate having a thickness of about 6 mm is butt-welded as the workpieces 1 and 1, and the welded portion 8 between the workpieces 1 and 1 is The constraint jig 2 is supported and fixed in a cantilevered state from both ends by constraint welding 3 to the inner wall surface 2a and the opposing inner wall surface 2b. It vibrates in conjunction with the vibration applied to.

Reference numeral 18 denotes a vibration detector which is attached near the welded portion 8 and detects vibration amplitude and acceleration near the welded portion 8, and 21 denotes a lead wire connected to the detector 18.

Using the welding apparatus constructed as described above, a flux cored wire having a diameter of 1.4 mm is used as the welding wire 14, and carbon dioxide gas is used as a shielding gas for enclosing the welding metal and the wire. 6m thick
A description will be given of the welding operation of the embodiment in which the butt-welding of the m-th copper plate is performed using a V-shaped groove.

When the exciter 6 is operated with an appropriate amplitude and cycle, the welded portion 8 of the workpiece 1 vibrates via the restraining jig 2. In this embodiment, the vibration has a frequency of 60H.
z sine wave excitation, amplitude 0.05mm ~ 0.1mm
And When the bogie 12 travels simultaneously with the start of welding by the torch 11, an arc is generated between the wire 14 and the welded portion 8, and the base material of the welded portion 8 is partially melted while being consumed. The wire 14 as an electrode is melted, and a molten metal is formed so as to fill the V-shaped groove of the welded portion 8.

At this time, the molten metal is agitated by the vibration from the vibrator 6, so that the release of gas such as hydrogen, which causes blowholes in the welded portion 8, is promoted and scattered. The attachment of spatter to the workpiece 1 is prevented. Further, since the welded portion 8 is vibrated by the vibrator 6, the molten metal and the vicinity of the welded portion 8 solidify while being plastically deformed. Thereby, the occurrence of residual stress and welding distortion is suppressed.

The vibration acceleration and amplitude near the welded portion 8 are detected by a vibration detector 18 and fed back to a control device (not shown). In the control device, based on the feedback signal, the moving speed of the welding torch 11,
The feeding speed and the like of the welding wire 14 are controlled.

In the material 1 to be welded as described above, the slag covering the surface of the weld metal after the welding was spontaneously peeled off due to the temperature drop of the welded portion 8 and the vibration with the passage of time. Thereby, the slag removal work was reduced, and the workability was significantly improved. After welding, the residual stress in the welded portion 8 was measured by a stress relaxation method using a Χ-ray stress measuring device and a strain cage. As a result, it was confirmed that the residual stress was reduced by about 30% in the case where welding was performed without vibration by the vibrator 6.

In the above embodiment, the butt welding of the copper plate has been described, but the present invention is not limited to this.
It can also be applied to butt welding and fillet welding of bars, square bars and pipes.

[0024]

As described above, according to the present invention,
Vibration is applied to the welded portion of the material to be welded, both ends of which are restrained and supported during welding, so that the molten metal in the high temperature state and its vicinity can be solidified while being plastically deformed. Reduction can be realized, and blow holes are prevented from being generated, so that a high-quality welded product can be obtained.

In addition, the spatter adhered to the material to be welded is reduced, and the slag can be spontaneously peeled off by vibration. Therefore, the welding efficiency including the incidental work is greatly improved, and the cost of welding products is reduced. Is made.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a welding device according to an embodiment of the present invention.

FIG. 2 is an external perspective view of a workpiece attachment portion in the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 welded material 2 restraining jig 3 restrained welding 5 main body of electromagnetic vibration device 6 vibrator 8 welded portion 11 torch 12 bogie 14 wire 18 vibration detector

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B23K 37/04 B23K 37/04 X

Claims (2)

[Claims] When welding an object to be welded by generating an arc between opposed materials to be welded, welding is performed while restraining both ends of the material to be welded and applying vibration to a portion to be welded. A welding method characterized in that: 2. A constraining jig for supporting opposite ends of a material to be welded in a constrained state, a welding torch for generating an arc in a to-be-welded portion, and a welding torch via the constraining jig. A welding device, comprising: a vibration device that imparts vibration.