JPH0663756A - Welding distortion preventing method for tee type joint panel - Google Patents

Abstract

PURPOSE:To produce a conicise welded structure free from distortion at the low cost by bending both ends parallel to a weld line of sheet metals at a right angle to the direction of welding face and heating the weld zone rear side of the sheet metals in advance with a high energy beam. CONSTITUTION:The reverse angular distortion is easily generated on the sheet metals 3 before fillet arc welding by advance heating of the high energy beam and the angular distortion can be prevented by operation that this reverse distortion becomes flat and operation that the unbalance of arc heat distribution on the sheet surface at the time of fillet welding is moderated by heating. In addition, rigidity of a cross section is increased by bending both ends parallel to the weld line of the sheet metals 3 almost at a right angle to the direction of welding face and as a result, backling deformation is prevented. Accordingly, in the Tee type joint panel formed by welding >= one vertical aggregates 4 to the sheet metals 3, flat panel material with very little angular distortion and buckling distortion can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing welding distortion of T-shaped welded joints of thin metal plates.

[0002]

2. Description of the Related Art Thin metal plates are generally used in many structures such as high-speed boats, fishing boats, railway vehicles, bridges, buildings, and tanks. These structures are assembled and constructed by welding the metal thin plates as the raw materials. Is normal. However, there is a problem that welding distortion is likely to occur in the welding and assembling process of the thin metal plate. For example, when the reinforcing vertical aggregate is welded to the outer plate material to assemble it, if the corners of the vertical aggregate are subjected to fillet arc welding, the welding bead portion as shown in FIG. Buckling deformation strain (H
1) and angular distortion strain (H2) are likely to occur. When this deformation strain occurs, the quality of the welded structure material deteriorates, and there is a problem such as an increase in wave resistance during navigation when used in high-speed boats. Has been done.

In order to solve these problems, (a) mechanical restraints are performed in advance, or (b) or after the welding and assembly is completed, the welded portion or its vicinity is locally heated in spots or linearly and then rapidly cooled to remove strain. (Aluminum alloy welding distortion prevention manual, Light Metal Welding Structure Association) (c) Simultaneous heating from the back side (Japanese Patent Laid-Open No. 179565/1983).
However, there is a problem in that the work time and man-hours for that purpose are large. Further, the effect is limited, and it is difficult to completely remove the strain even with these methods, and there is a problem that the buckling deformation strain remains.

[0004]

SUMMARY OF THE INVENTION The inventors of the present invention have previously solved the problem of performing continuous fillet arc welding with such a T-type welded joint, but the back side of the welded portion of the welded thin plate is subjected to a high energy beam. A method of preceding heating to meat arc welding has been proposed (for example, Japanese Patent Application No. 2-75965). By this method, the above deformation can be reduced, and in particular, the angular deformation can be greatly reduced. However, even with this method, it was not possible to completely prevent the buckling deformation of the welding deformation for the thinner plate.

An object of the present invention is to solve the above problems and to make it possible to manufacture a welded structure which is simple, low in cost and free of distortion.

[0006]

SUMMARY OF THE INVENTION The essence of the present invention is to prevent welding deformation by simultaneously performing measures for preventing angular deformation and buckling deformation by different methods. That is, in a T-shaped joint panel formed by continuous fillet arc welding of one or more vertical aggregates to a thin metal plate, both ends parallel to the welding line of the thin metal plate are bent substantially at right angles to the welding surface direction. ,
Further, it is a welding distortion preventing method for a T-shaped joint panel, characterized in that the back side of the welded portion of the thin metal plate is heated with a high energy beam prior to fillet arc welding.

Here, mild steel, aluminum alloy plate and the like can be preferably applied as the kind of the metal thin plate. As the high-energy beam, TIG, plasma arc, electron beam, laser beam, acetylene, propane burner, etc. can be preferably used, and the degree of heating can be selected by conducting preliminary experiments appropriately depending on the plate thickness, welding conditions, etc. Good. The interval between the high-energy beam and the fillet arc welding when heating the back side of the thin metal plate for continuous fillet arc welding with the T-shaped weld joint in advance needs to be 1 mm or more, preferably 50 to 1000 mm in advance. Is desirable. The degree of prior heating is not particularly limited, but usually it is sufficient to melt the very surface layer (about 0.1 mm) of the thin metal plate,
Actually, the optimum degree may be selected by preliminary experiments etc. for each plate thickness and fillet arc welding conditions. As shown in FIG.
The amount of bending at both ends of the plate at substantially right angles to the welding surface direction is not particularly limited, but normally 1t to 10t (t: plate thickness) is desirable. The bending direction may be any direction, but FIG.
As shown in Fig. 5, when the T joint is aligned in the same direction as the vertical aggregate, the bent portion does not appear on the outer surface of the thin metal plate, and when the plate including the plurality of T joints is welded, the bent portion can be welded. It has advantages such as easy welding. The type of fillet welding method is not particularly limited, but MIG welding, CO ₂ welding, mag welding, or the like can be usually used, and is appropriately selected according to the type of metal thin plate. Although the present invention can be applied to a plate thickness of 10 mm or less, it is preferably 2 to 5 mm.

[0008]

It is considered that the reason why it is possible to prevent the angular distortion of the T-joint by the preceding heating of the high energy beam is due to the following two reasons. That is, heating by the high-energy beam easily causes reverse angular deformation strain in the thin metal plate before fillet arc welding, and this reverse strain is canceled by the subsequent deformation by fillet arc welding, resulting in a flat strain. It is considered that this is due to the action and heating that alleviate the imbalance in the arc heat distribution on the plate surface during fillet welding. On the other hand, the effect is small when the position of heating with the high energy beam is directly below or behind the arc of fillet arc welding.
This is because once the T-joint is formed by melting and solidifying by fillet arc welding, the restraining force becomes larger than that of the flat plate before welding, and it is difficult to restore the original state by strain correction after that. It is considered that the heat balance effect is deteriorated due to the fact that the heat is applied and the heat is already generated by the welding heat.

The reason why the buckling deformation can be greatly reduced is considered as follows. That is, when fillet welding of a thin metal plate is normally performed, shrinkage (vertical shrinkage) occurs in the welded portion in the welding line direction. Due to this contraction, a stress that causes a longitudinal contraction also acts on the thin metal plate around the welded part, but since it is a thin plate, the waist is weak and this easily causes buckling deformation, resulting in the shape shown in Fig. 1 above. It seems to be. On the other hand, as shown in FIG. 3, by bending both ends of the thin metal plate parallel to the welding line at a right angle to the welding surface direction, the rigidity of the cross section is increased, and as a result, buckling deformation is prevented. To be

[0010]

[Examples] Both ends of a plate parallel to the portion to be welded of the following outer plate material were previously bent at a right angle of 10 mm in the welding surface direction.・ Test piece Outer plate material: JIS A5083-O aluminum material Thickness 3 mm, width 1500 mm, length 3000 mm Vertical aggregate: JIS A5083-O aluminum material Thickness 4 mm, width 60 mm, length 3000 mm Next, as shown in FIG. Temporarily, while pressing three aggregates in order from the plate edge of the outer plate material at a position of 240 mm at intervals of 500 mm so as to be substantially at right angles to the outer plate material and with no gap at the boundary between the vertical aggregate and the outer plate material. After attachment welding
Set the back side of the outer plate material 200 mm ahead of each welding position 3
While preheating with the arc of the TIG welding machine torch of the table,
Continuous automatic fillet welding of three vertical aggregates was performed with six MIG welding machine torches. The welding conditions are as follows. MIG 180 (ampere) 18 (volt) TIG 150 (ampere) 18 (volt) Welding speed 2000 mm / min

At this time, the maximum value H1 of the buckling deformation amount and the angular deformation amount H2 at a position 100 mm from the welding center were measured. The results are shown in Table 1. In addition, as a comparative example, Table 1 also shows the results of strain in the case where the bending of the plate end and the back side TIG heating are not performed under the above conditions.

[0012]

[Table 1]

As shown in Table 1, in the comparative example, both buckling deformation and angular deformation are about 15 mm, but in the T-joint according to the present invention, the buckling deformation amount is 0.2 mm and the angular deformation amount is It was 0.4 mm, which was extremely small and was reduced to about 1/50 of that of the comparative example, and an extremely flat T-shaped joint could be obtained.

As described in detail above, according to the welding method of the present invention, in a T-shaped joint panel formed by welding one or more vertical aggregates to a thin metal plate material, angular distortion and buckling distortion are extremely high. It is possible to provide a small number of flat panel materials. Therefore, it is possible to reduce the number of man-hours and the construction period for ships and the like, resulting in a significant cost reduction. In addition, there is an advantage that it can be performed more easily than other strain removal methods and strain prevention methods.

[Brief description of drawings]

FIG. 1 is a perspective view showing a strain in a T-type welded joint.

FIG. 2 is a sectional view of a welding process showing an embodiment of the present invention.

FIG. 3 is a perspective view showing a T-type welded joint after welding according to the present invention.

[Explanation of symbols]

 1 Bent part 3 Metal thin plate (outer plate material) 4 Vertical aggregate 5 Weld bead 10 MIG welder 11 TIG welder H1 Buckling deformation amount H2 Angular deformation amount l Distance from welding center

Claims (1)

[Claims] 1. A T-shaped joint panel formed by continuous fillet arc welding of one or more vertical aggregates to a thin metal plate, and both ends parallel to the welding line of the thin metal plate are bent at substantially right angles to the welding surface direction. A method for preventing welding distortion of a T-joint panel, which comprises bending and heating the back side of the welded portion of the thin metal plate with a high energy beam prior to fillet arc welding.