JPS62176692A - Production of clad steel pipe - Google Patents

Abstract

PURPOSE:To surely prevent an undercutting by performing a seam welding by laser beam after forming a clad steel plate in cylindrical shape. CONSTITUTION:The clad steel plate 1 formed in cylindrical shape by a roll forming, etc. is passed through the squeezing stand 5 consisting of the lower roll 2, the squeezing roll 3 giving an upsetting and the squeezing top roll 4 of the adjusting roll for causing no step difference and subjected to seam welding by a laser beam welding machine 6. The laser welding machine 6 is located at the upper part of the butt part at the downstream side of the squeezing center and welds the I shaped butt part without any gap formed by the squeezing stand 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an improvement in a seam welding method for manufacturing Rede welded clad steel pipes.

(Prior art) One method for manufacturing clad steel pipes in which the inner and outer layers of the steel pipe are made of different materials is to form a clad steel plate into a 9-node shape using rolls, etc., and then seam weld both end faces with a rede. Therefore, there is a method of manufacturing a steel pipe in which the inner and outer layers of the welded portion are made of different materials.

However, in Rede welding, even if a minute gap is created at the butt portion, undercuts will occur, resulting in poor welding. On the other hand, when forming steel pipes using rolls, etc., it is difficult to ensure that the butt part is shaped like a square as shown in Figure 2 (a) with no gaps, and it is difficult to form the butt part into a V-shape as shown in Figure 2 (b) or a shape with no gaps. Figure 2 (C)
This often results in an inverted V-shaped gap like this. For this reason, when manufacturing clad steel pipes by Rede welding, there is a problem in that undercut defects 9 as shown in FIGS. 3(b) and 3(e) are likely to occur in the welded portion.

(Problems to be Solved by the Invention) The present invention attempts to reliably prevent the occurrence of undercuts in the production of clad steel pipes that are seam welded by Rede.

(Means for Solving the Problems) The inventors of the present invention conducted research to solve the above problems, and as a result, they obtained the following knowledge. That is, when welding both end faces of a cylindrical A plate, as shown in Figure 1, by pressurizing and applying upseratra with a squeeze roll, it is possible to reliably form an I-shaped butt with no gaps. Obtainable. This is because by applying a thrust, plastic deformation is applied to both end faces of the steel plate, even in the case of V-formation or reverse-open butt as shown in Figure 2 (b) or Figure 2 (C). This is because it is possible to provide an I-shaped butt with no gaps.

The present invention has been made based on the above knowledge, and the undercut is removed by laser welding a steel plate formed into a cylindrical shape by roll forming, etc., pressurized with a squeeze roll to give an upset, and then laser welded. It is characterized by its reliable prevention.

(Example) The present invention will be described below with reference to embodiments shown in the drawings. FIG. 1 is an explanatory diagram of a squeeze and rede welding device for carrying out the present invention.

Clad steel plate 1 formed into a cylindrical shape by roll forming etc.
are passed through a squeeze stand 5 consisting of a lower roll 2, a squeeze roll 3 for giving an upset, and a squeeze dog roll 4 which is an adjustment roll to prevent the formation of a step, and are seam welded by a Rede welder 6. in this case,
The left and right squeeze rolls are movable in the left and right directions using hydraulic cylinders, etc., and this allows the roll spacing to be adjusted to give an upset to the abutting portion. The appropriate amount of upset varies depending on the plate thickness, but for example, in the case of a plate thickness of 6 mm, it is about 0.5 mm. If the amount of upset is too small, undercuts are likely to occur, while if it is too large, the weld bead becomes convex and requires bead cutting.

The laser welder 6 is installed on the downstream side of the squeeze center at a position approximately 150 m+ above the abutting portion, and welds the I-shaped abutting portion with no gap formed by the squeeze stand. The rede welding position varies depending on the external shape and plate thickness, but is approximately 10m downstream of the squeeze center.
The location is good. This is because if it is too close to the squeeze center, it may not be possible to obtain an I-shaped weld with no gaps, and conversely, if it is too far from the squeeze center, gaps will occur again due to springback. When rede welding clad steel plates, it is desirable to weld as fast as possible in order to fully form the weld into cladding, so C
A laser generator capable of high output, such as an O2 radar, is used, and the radar beam is focused to a beam of about 0.5 m, for example.

(Effects of the Invention) As explained above, in the present invention, after forming a clad steel plate into a cylindrical shape, seam welding is performed using a rede. Undercutting can be reliably prevented by applying pressure to the steel plate with a squeeze roll to give it an upset, and then performing rede welding.

[Brief explanation of drawings]

Figures 1 (a) and (b) are diagrams showing an embodiment of the present invention, Figure 2 (a) is a diagram showing a butting part of materials in an I-shaped case with no gap, and Figure 2 (b) is a diagram showing an example of the present invention. ) is for the same V shape,
Figure 2 (e) shows the case where a gap occurs on the outer surface side, and Figure 2 (e) shows the case where the same inverted V shape is used, and a gap occurs on the inner side, and Figure 3 (&) shows the case where proper welding is performed. FIG. 3(b) and FIG. 3(e) are diagrams showing the cross-sectional shape of the welded portion when an undercut occurs. 1... Clad steel plate 2... Lower roll 3...
Squeeze roll 4... squeeze top roll

Claims (1)

[Claims] A method for producing a clad steel pipe, which comprises forming a clad steel plate into a cylindrical shape using a roll or the like, and then performing seam welding with a laser while squeezing both end faces.