JPS598866Y2 - ERW steel pipe manufacturing equipment - Google Patents

Description

[Detailed description of the invention] This invention aims to clean the tubular skelp edge, stabilize the welding point, and obtain high-quality welding when manufacturing ERW steel pipes by continuously shaping and welding band-shaped skelps. This relates to steel pipe manufacturing equipment.

In the manufacturing method of ERW steel pipes, for example, high frequency induction welding,
Skelp 1 continuously shaped into a tubular shape as shown in Fig. 1
The edge portion 7 of the tubular squelp (hereinafter referred to as a tubular squelp) is heated to a welding temperature by an eddy current induced by a high frequency current flowing through the work coil 2, and is pressure welded by a squeeze roll 4.

The edge portion 7 of the tubular scale 1 contains water used in the ceremonial process,
Foreign matter such as a paste-like substance (hereinafter referred to as metal powder paste) that is a mixture of lubricant for forming and metal powder generated in this process is attached.

Normally, most of the lubricating liquid adhering to the edge part 7 evaporates during the heating process, and its residue and metal powder paste are also removed from the welding point 9 by the pressurizing action of the squeeze roll 4 together with the oxide produced on the edge part 7. Extruded.

However, as the proportion of elements such as Cr, Si, and Mn in the steel increases, it becomes difficult for the oxides forming on the edge 7 to be extruded even by the pressurizing action of the squeeze roll 4, resulting in a welding process called penetrating welding. This often results in defects.

Therefore, when manufacturing high-grade steel or alloy steel containing a large amount of elements such as Cr, Si, and Mn, the welding atmosphere is adjusted to an inert or reducing non-oxidizing atmosphere, and the edge portion 7 of the tubular skeleton 1 is Preventing oxides from growing is also considered to be an effective means.

As a technical solution, for example, US Patent No. 280
No. 0561 and No. 2991345 show that a jet of inert gas is blown onto the weld from a nozzle, but this method is not effective because it is considered that ambient air is engulfed by the gas jet. It cannot be called a means.

In Japanese Patent Application Laid-Open No. 53-29257, an inert gas sealing device is arranged between the work coil and the welding point at the upper part of the tubular scalp edge, but there is an opening below the wiping device, and the tubular It is impossible to maintain a completely non-oxidizing atmosphere inside the skelp.

In addition, in order to remove the metal powder paste adhering to the scalp edge, a foreign matter wiping cloth or brush is placed, but the wiping cloth is not suitable for the following reasons: (1) The surface of the scalp edge is uneven and sharp. The fabric has sharp corners, which can damage the fabric and prevent continuous operation.

(2) When manufacturing electric resistance welded steel pipes using high-frequency induction welding, the line speed is high, and even if you try to constantly clean the scalp edges, it is not possible to supply cloth, and the line must be stopped when changing cloth.

(3) The opening width of the scalp edge is narrow, so it is not possible to insert the wiping roll as shown in the figure, and the wiping cloth does not fit into the roll shape.

It has such drawbacks that it is not suitable for practical use.

In addition, the brush has the following characteristics: (1) The opening width of the scalp edge is narrow, and even if the brush can be inserted, it is impossible to wipe the scalp edge evenly.

(2) The metal paste wiped off with the brush adheres to the brush and re-adheres to the scalp edge on the downstream side of the brush, so that no wiping effect can be expected.

On the other hand, in Japanese Patent Application Laid-Open No. 52-60268, an "avalanche" phenomenon occurs in the molten metal upstream of the squeeze roll due to electromagnetic force, and oxides such as Cr, Si, Mn, etc. cannot be completely removed and the penetrator is damaged. It is said that he will be alive.

In view of the above-mentioned shortcomings of the conventional technology, the inventors of the present invention photographed the basic phenomena of the ERW steel pipe manufacturing method using high-frequency induction welding using a 16 mm high-speed camera, and observed in detail the occurrence of defects at weld abutments.

As a result, as shown in FIGS. 2 and 3, the occurrence period of the aforementioned "avalanche" phenomenon completely coincides with the oscillation period of the welding point 9 in the line direction, and the tubular skeleton inside the work coil It has been found that the impedance of the eddy current circuit passing through the outer periphery of the surface of the welding point 9 and the welding point 9 changes due to the fluctuation of the welding point 9, and that penetration occurs due to excess or deficiency of the molten metal 8.

This period corresponds to the lateral vibration period of the squeeze roll 4.

This fact is completely new knowledge that was not recognized by the United States.

The present invention was developed based on this new knowledge. During high-frequency welding of ERW steel pipes, the metal paste on the skelp edge is removed by a gas jet supplied from a group of nozzles, and the fluctuation of the melting point is suppressed by a seam guide. This suppresses the "avalanche" phenomenon of molten metal and provides a method for preventing the occurrence of penetrators.

The present invention will be explained in detail below with reference to FIG.

The nozzle groups 3 to 3 are mounted between the seam guide 6 and the work coil 2, in the tangential direction of the tubular skelp 1, facing the skelp edge 7, and so that the angle with respect to the line axis direction can be adjusted.

This angle is preferably in the range of 60° to 90°. The cross-sectional area of the nozzle groups 3 to 3 is 3 to 50 mm2, and 3 to 1
A high pressure gas jet of 0 kg/cm' is supplied.

The nozzle groups 5 to 5 are arranged on the upstream side of the welding point 9 and on the left and right sides of the welding point 9, respectively, so that the gas jet can be supplied from diagonally above the squeeze roll 4.

This position is preferably 50 to 200 mm upstream from the welding point and within a range of 10 to 100 mm to the left and right of the welding point.

The cross-sectional area of the nozzle groups 5 to 5 is 3 to 50 mm2, and 3 to 1
A high pressure gas jet of 0 kg/cm2 is supplied.

The seam guide 6 is arranged upstream of the welding point 9, is always in contact with the squelp edge 7, and is controlled by the advancing speed of the tubular squelp 1.
It is installed so that it rotates at the same circumferential speed as the rotation speed.

For reasons to be described later, it is preferable that the seam guide 6 is normally located 150 to 500 mm upstream of the welding point and has a thickness of 5 to 20 mm.

The present invention is constructed as described above, and the metal paste adhering to the skelp edge 7 of the continuously shaped tubular skelp 1 is completely removed by supplying a gas jet through the nozzle groups 3 to 3. be done.

Also, does squeeze roll 4 overheat due to eddy current? In order to prevent this, cooling water is supplied for cooling, and this is done by supplying a gas jet through the nozzle groups 5 to 5 to prevent it from flowing into the vicinity of the welding point 9.

In this way, the inflow of foreign matter into the welding point 9 is completely blocked.

On the other hand, the squeeze roll 4 that presses and presses the scalp edge 7 at the welding point 9 has a lateral deflection amount of h per rotation due to manufacturing dimensional accuracy.

In conventional welding, where the seam guide 6 is placed at a position 500 mm or more upstream of the welding point 9 and the thickness is 5mm or less, it is impossible to hold the welding point 9 within 5 mm. could not be prevented.

However, according to the present invention based on experimental results, the defects caused by the lateral vibration of the squeeze roll 4 can be overcome, and stable welding can be performed without the "swelling" phenomenon.

Examples manufactured using the apparatus of the present invention according to the configuration shown in FIG. 1 and results of manufacturing according to a conventional method will be described below.

Welding equipment: Vacuum tube type high frequency induction welding equipment Frequency: 300 KHz Output: 250 KW Pipe material: Pipe manufacturing dimensions: 38φmm x 2. O tmm Steel pipe material SUS 3Q4 Pipe making speed 50 m/min Seam guide position Squeeze roll upstream side 150 mm
~500mm? In the case of the present invention, the nozzle cross-sectional area was set to 5 mm2, and compressed air at an original pressure of 4 kg/cm was supplied, keeping the conditions of 5 to 20 mm or more constant.

The weld defect occurrence rates of the resulting products were subjected to a weld fracture test and are compared, and are shown in FIG.

As a result of manufacturing according to the present invention, no defects were observed at all.

As explained above, the apparatus of the present invention can produce electrical resistance welded steel pipes having extremely high-quality welds compared to conventional apparatuses, and is an extremely useful invention industrially.

Furthermore, it has become possible to manufacture an electric resistance welded steel pipe having a high quality welded part without having to spend a huge amount of money to create a non-oxidizing atmosphere near the welded part.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the structure of the electric resistance welded steel pipe manufacturing apparatus of the present invention, Fig. 2 is a perspective view showing the "avalanche" phenomenon of molten metal, Fig. 3 is a perspective view showing a good welding state, FIG. 4 is a diagram comparing the results of destructive inspection of product welds by manufacturing method. 1: Tubular skelp, 2: Work coil, 3: Nozzle, 4
: Squeeze roll, 5: Nozzle, 6: Seam guide, 7
: Skelp edge, 8: Molten metal, 9: Welding point.

Claims (1)

[Scope of claim for utility model registration] 1. In the electric resistance welded steel pipe manufacturing device, (a) at an intermediate position between the seam guide 6 and the work coil 2,
Nozzle groups 3 to 3 for supplying gas jets are arranged so as to be perpendicular to the tubular squelp 1, facing the squelp edge 7, and adjustable in angle with respect to the line axis direction. (b) Nozzle groups 5 to 5 are arranged to be able to supply a gas jet to the squeeze roll 4 from diagonally above. (c) A seam guide 6 is arranged at a position intermediate between the upstream side of the welding point and the final shape roll. An electric resistance welded steel pipe manufacturing apparatus characterized by having the structure as described above. 2. The electric resistance welded steel pipe manufacturing apparatus according to claim 1, wherein the angle of the nozzle groups 3 to 3 facing the squelp edge 7 can be adjusted in the range of 60° to 90° in the line axis direction. 3 Claims for Utility Model Registration in which the nozzle groups 5 to 5 for supplying gas jets to the squeeze roll 4 are arranged 50 to 200 mm upstream from the welding point 9 and in a range of 10 to 100 mm to the left and right of the welding point 9 The electric resistance welded steel pipe manufacturing apparatus according to item 1. 4. The electric resistance welded steel pipe manufacturing apparatus according to claim 1, wherein the seam guide 6 has a thickness of 5 to 20 mm and is disposed at a position 150 to 500 mm upstream of the welding point 9.