JPH11342419A - Clad steel pipe manufacture by press roll piercing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a clad steel pipe having a good inner surface status by rolling the pipe while supplying a lubricating agent to an inside of a working side inner pipe in a rolling mill, when the clad steel pipe is rolled by a press rolling piercing machine. SOLUTION: In case of a rolling by the press roll piercing machine, a rolling member 2 to be rolled wholly contacts with a plug 3 in a circumferential direction and no clearance is generated. Even when the lubricating agent is not applied in advance to whole of the inner face of the rolling member, the lubricating agent is supplemented between the plug 3 and the rolling member 2 by inserting the lubricating agent in an inside of a working side inner pipe in the rolling mill so that the lubrication is made possible across the whole length of the rolling member 2. That is after the inner pipe is inserted into a penetrating hole across the whole length of a rectangular cross-section steel piece, the clad steel pipe is manufactured by rolling a billet, which joined a boundary part between an end face of the working side steel piece in the rolling mill and the inner pipe, by the press roll piercing machine. In that case, the lubricating agent is supplied to the inside of the bite-in side inner pipe in the rolling mill. A lubricating agent containing an iron oxide of Fe2 O3 and the like as a main element and a glass at 15 wt.% is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner surface lubrication method for producing a clad steel pipe using a press roll punch.

[0002]

2. Description of the Related Art Conventionally, carbon steel and low alloy steel are generally used as steel pipes for oil and natural gas wells.
In recent years, development of petroleum and natural gas wells containing highly corrosive components such as H ₂ S and CO ₂ has become active due to resource depletion. Especially in an environment containing a large amount of H ₂ S,
Austenitic stainless steel, duplex stainless steel, or high Ni alloys are used, but they are expensive,
Due to the relatively low proof stress, there is an increasing need for carbon steel and clad steel pipes which are made by laminating them.

[0003] The present inventors have developed a method of rolling clad steel pipes using a press roll drilling machine. After the insertion, at least the billet in which the steel slab of the end face on the side that bites into the rolling mill and the boundary portion of the inner pipe are joined is rolled by a press roll punch. The plug used in this drilling machine is made of 3% Cr-1Ni-based low alloy steel material,
In order to secure the heat insulation property, heat treatment
A treatment for forming an oxide scale such as ₃ O ₄ and FeO is performed. In the rolling of clad steel pipe by press roll drilling machine, if a hard-to-work material such as austenitic stainless steel or high Ni alloy is used for the inner pipe, the oxide scale on the plug surface will be worn away early, and the inner surface flaw caused by seizure will be reduced. May occur. However, in rolling a clad steel pipe by a press roll punch, there is no effective measure for preventing inner surface flaws.

On the other hand, a clad steel pipe is manufactured by an inclined rolling mill by using a material in which an inner pipe is closely fitted to an outer pipe, and then the outer pipe and the inner pipe are welded and fixed at their end faces. Is what you do. Also in this method, when a difficult-to-work material such as austenitic stainless steel or a high Ni alloy is used for the inner tube, cracks and flaws may be generated on the inner surface by inclined rolling. To solve this problem, Japanese Patent Application Laid-Open
Japanese Patent Application Publication No. 182010 describes a method of applying a lubricant substantially made of water glass to the inner surface of a mixture tube (inner tube) before heating.

[0005]

However, the above-mentioned method is effective when a mandrel bar is used as a tool on the inner surface side, but requires a large-scale apparatus for applying a lubricant to the inner surface. Furthermore, when a lubricant substantially consisting of water glass is applied to a scaled plug, the scale applied to the plug surface is melted and an internal flaw is generated due to damage of the plug, so that application to a press roll punch is difficult. .

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a rolling method for preventing inner surface flaws in rolling a clad steel pipe by a press roll punch.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and at least after inserting an inner pipe into a through-hole formed in a steel slab having a rectangular cross-section and extending over the entire length of the slab. In the production of a clad steel pipe to be rolled by a press roll punching machine with a billet joined to the end of the steel piece on the end face on the side of the rolling mill and the boundary of the inner pipe, a lubricant is preferably contained in the inner pipe on the side of the rolling mill, preferably Is mainly composed of iron oxide such as Fe ₂ O ₃ ,
This is a method for producing a clad steel pipe in which a lubricant containing 15% by weight of glass is supplied and rolled.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The rolling method according to the present invention will be described in detail below. In rolling with a press roll punch, as shown in Fig. 1, the plug and the material to be rolled were in full contact in the circumferential direction and there was no gap. Even if the lubricant is not applied to the surface in advance, the lubricant is inserted between the plug and the material to be rolled by inserting the lubricant into the inner tube that bites into the rolling mill, It has been found that lubrication is possible over the entire length.

On the other hand, in the rolling by the inclined rolling mill, as shown in FIG. 2, there is a gap in the circumferential direction between the plug and the material to be rolled, so that the lubricant is supplied only to the side that bites into the rolling mill. According to the method, the lubricant escapes toward the rear end of the plug along with the rolling while the lubricant adheres to the rolled material from the gap between the plug and the material to be rolled, so that it is difficult to supplement the lubricant on the plug surface.

The lubricant used in the present invention is mainly composed of iron oxide such as Fe ₂ O ₃ which has a low possibility of melting the scale applied to the plug and is excellent in heat insulation and lubricity. A lubricant containing glass is preferred. Next, when the lubricant is inserted into the inner tube, the lubricant can be easily supplied into the inner tube by wrapping the lubricant in an aluminum foil and forming the lubricant into a cylindrical shape.

[0011]

<Example 1> A carbon steel square steel piece with a side of 80 mm and a length of 700 mm with a hole having a diameter of 39 mm at the center was formed into an INCOLO having an outer diameter of 37.5 mm, a wall thickness of 6 mm and a length of 700 mm.
The inner tube of Y825 was inserted. After the material to be rolled is heated to 1250 ° C., the outer diameter is 93 mm and the wall thickness is 23 mm using a press roll punch.
Rolled. At this time, 50 g of a lubricant containing 85% by weight of Fe ₂ O ₃ and the remainder consisting of glass was wrapped with aluminum foil, and inserted into the inner surface of the inner tube on the side to be bitten by the rolling mill immediately before rolling. For comparison, rolling was performed without using a lubricant. As a result of observing the inner surface of the clad steel pipe after rolling and observing the inner surface, in the case of the method of the present invention using a lubricant, a good inner surface could be obtained, but the lubricant was used regardless of the present invention. In the case of the method which was not performed, an inner surface flaw caused by the seizure of the plug was generated, and only a product whose commercial value as a clad steel pipe was reduced by half was obtained.

[0012]

According to the present invention, when a clad steel pipe is rolled by a press roll punch, a clad steel pipe having good inner surface properties can be obtained.

[Brief description of the drawings]

1A is a schematic diagram of rolling by a press roll punch, and FIG. 1B is a cross-sectional view taken along line AA of FIG.

FIG. 2A is a schematic view of rolling by a tilt rolling mill,
(B) is an AA sectional view of (a).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Roll of press roll piercing machine 2 ... Material to be rolled 3 ... Plug of press roll piercing machine 4 ... Mandrel bar for plug support of press roll piercing machine 5 ... Roll of inclined rolling mill 6 ... Plug of inclined rolling mill 7 ... Rolled material 8: Mandrel bar for plug support of inclined rolling mill 9: Guide shoe of inclined rolling mill

Claims (2)

[Claims] After inserting an inner pipe into a through-hole formed in a steel slab having a rectangular cross section and extending over the entire length of the slab, at least a boundary between the steel slab on the end face on the side to be engaged with the rolling mill and the inner pipe is joined. A method for producing a clad steel pipe, in which a billet is rolled by a press roll drilling machine, wherein a lubricant is supplied to an inner pipe on a side to be meshed with the rolling mill and rolling is performed. 2. The method for producing a clad steel pipe according to claim 1, wherein the lubricant is mainly composed of iron oxide such as Fe ₂ O ₃ and contains 15% by weight of glass.