JPS6163315A - Production of seamless cladding tube - Google Patents

Abstract

PURPOSE:To elevate a yield, workability and quality by placing a base material and fitting material in close contact each other with the jig of tube expansion having the flexible sealing hollow body filling up a fluid body in its inner part. CONSTITUTION:An inner tube 2 is inserted into the outer tube 1 consisting of a base material and fitting material. The jig 3 for tube expansion having a flexible sealing hollow body 9 is inserted into said inner tube 2 and a tube expansion is performed with expanding the hollow body 9 by placing a pressure on the inner part fluid body via an oil feed pipe 16. The double blank tube where the base material and fitting material are placed in close contact with each other is obtained with performing said working operation in order from one end part to other end part. Then after the seal welding of the base material and fitting material at both ends of said double blank tube a hot extension rolling work is performed with heating it to the prescribed temp.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application> The present invention relates to a method for manufacturing high quality seamless clad pipes economically and with high yields.

<Prior art> Recently, as seamless steel heavy equipment used in harsh conditions of high temperature and highly corrosive environments, such as oil country tubular goods in deep wells, nutless steel is being used for outer pipes made from a base material of carbon steel or low alloy steel. Seamless pipes manufactured by lining the inner pipe with a mixture of corrosion-resistant materials such as N1 alloy steel and N1 alloy steel have come to be widely used as a material that is advantageous in terms of economic quality and quality.

Seamless clad f used for this type of application basically requires a complete metallurgical bond between the base material and composite material, but the manufacturing method on an industrial scale is usually includes the following:

That is, first, for example, an inner tube made of a composite material is inserted into an outer tube made of a base material, and the loosely fitted inner and outer tubes are mechanically tightened to obtain a double-layered tube. Next, the outer tube and the inner tube are welded together at both ends of this double-layered tube, and then heated to a predetermined temperature, and then passed through, for example, an inclined roll punching machine, followed by a plug mill, an Arasel mill, or a pilger. By hot stretching and rolling through a mill or the like, the inner and outer tubes are completely crimped to obtain a seamless Kutsurad tube.

In the above manufacturing method, two methods are currently used to mechanically bring the loosely fitted inner and outer tubes into close contact: (1) cold open drawing method (2) water pressure expansion method.

■The cold drawing method is a method in which the loosely fitted inner and outer tubes are placed in a cold drawing machine and cold drawn to make them fit together, but this method can be easily applied to any size of raw tube. However, it requires a large drawing machine, which is not an economic problem, and it is necessary to cut off about 200 to 300 U of each of the front and rear ends of the double-layer tube after drawing, which results in a large yield. There is a problem with the decline.

Compared to the hydraulic pipe expansion method, the outer pipe is fitted with a jig of 1 μm of publicly known glue on both ends of the fitted inner pipe to seal the ends of the inner pipe. After water is injected into the inner tube from the μ jig to fill it, water pressure is applied inside 7 to expand and expand the inner tube and bring it into close contact with the outer tube. In this method, the truncation allowance at the end of the inner tube is sufficient to be about three times the tube thickness, so the truncation allowance is greatly reduced and the yield is improved compared to method ① above. Not only does this method require a considerable amount of cutting allowance, but this method requires the work of moving the 200-element pipe to a location where dedicated water pressure equipment is located in order to apply water pressure, which poses problems in workability. Also, when rolling a large amount of water, moisture may enter the gap between the inner and outer tubes, which may cause the product to peel.

Therefore, it has been strongly desired to develop a method for manufacturing seamless clad pipes that further reduces the cutting margin, improves workability, and eliminates the risk of product peeling due to the use of large amounts of water.〇<Objective of the Invention> The present invention is capable of producing seamless clad pipes that are significantly superior in terms of yield, workability, and cost compared to conventional cold drawing methods and hydraulic pipe expansion methods, and are free from the problem of products peeling off due to water, etc. It is intended to provide a method.

<Structure of the Invention> That is, the present invention provides a combustible seal in which an inner tube made of a base material or a composite material is inserted into an outer tube made of a base material or a composite material, and the inner tube is filled with a fluid. A pipe expansion jig having a hollow body is inserted, and the hollow body is expanded by applying pressure to its internal fluid to expand the pipe. By continuously holding the base material and the composite material, the base material and the composite material are brought into close contact with each other to obtain a t double base material pipe, and the base material and the composite material are sealed/L at both ends of this double base material.
-79 contact, and then heating it to a predetermined temperature and hot stretching and rolling.

A specific example of a method of obtaining an FC duplex tube in which the base material and composite material are brought into close contact with each other by tube expansion using a tube expansion jig in the method of the present invention described above will be shown below.

As shown in the cross-sectional view in Figure 1, an inner tube (2) that is slightly longer than the outer tube (1) is fitted, and a tube expansion jig (3) is attached to one end of the inner tube (2). set.

The structure of the tube expansion jig (3) is as follows. In other words, the jig (3) has flange-shaped fixing fittings (7/
X7J), a core rod (6), and both fixing fittings (7/
) (7 pieces), both ends of which are supported by ring-shaped backup metal fittings (8/X8 pieces), and a sealing hollow body (9) made of rubber, for example, filled with fluid, and the hollow It is provided inside the body (9) so as to cover its inner surface and is composed of a flexible steel lip αG.

The steel lip αO is a flat spring (b) which has a taper by gradually decreasing the VC thickness in the longitudinal direction from one end side to the other end side as shown in FIG. 1, as shown in the longitudinal sectional front view of FIG. A large number of them are arranged one on top of the other in the circumferential direction, and the whole has a cylindrical shape.

In addition, the backup metal fitting (at) on one end side (hereinafter, this side will be referred to as the rear end side) is constituted by a large number of pieces in a chain shape and has a ring shape, as seen in the longitudinal sectional front view of Fig. 4. Each piece is attached to a hollow rubber body (9) with a bolt (
(to)), and the retaining part (b) between the pieces is fixed by the stepped surface (
15/) and (154) come into contact and slide. That is, when the rubber hollow body (9) is expanded by hydraulic pressure, the step surface (15/) (15J) slides and expands in diameter accordingly. Then, the extension of the rubber hollow body (9) in the axial direction is restricted to prevent it from protruding outward. Note that the backup metal fittings (8 pieces) on the other end side do not have such an expansion/contraction function, and are simply a rigid body with a groove bottom.

When using the above-mentioned tube expansion jig, first, from one end of the inner tube to the required range of the fixing fitting (71) at the rear end of the inner tube (
2) into the hollow body (9) from the oil supply shaft αQ connected to the through hole (5) ((4/) is the outlet and (4J) is the inlet) passing through the core rod. The hollow body (9) is expanded by applying hydraulic pressure to, for example, oil filled in the hollow body (9), and the inner tube (2) is expanded by the expansion force. In this case, the steel lip αO is the wall thickness o on the backup metal fitting (81) side.
The diameter greatly expands at the 1st part and the hollow body (9
) also expands greatly, but in the thick part of the back-up metal fittings (8 pieces) 4AI at the tip that do not have an expansion/contraction function, the diameter expansion is gradually suppressed toward the tip, and the hollow body ( The expansion in 9) also takes a form similar to this. Therefore, as shown in the cross-sectional view of FIG. 2, the hollow body (9) expands from the back-up fitting (81) side at the rear end by a portion of, for example, about % of the total length of the hollow body (9), and the inner tube (2) expands. 1 to form a completely processed part Ct/) that is in close contact with the outer tube (1). In the remaining portion, for example, the fox portion, the tube expansion is insufficient, resulting in the formation of a tapered, f-shaped incompletely processed portion (mu) where the tube diameter gradually decreases from the completely processed portion (b). By adopting this type of tube expansion, internal and
Impurities such as air interposed between the outer tubes are successively pushed forward, and accumulation of these impurities between the inner and outer tubes is prevented.

By carrying out the tube expansion operation of the inner tube using the jig (3) as described above in order from one end of the inner tube to the other end so that the fully processed part continues with an appropriate weight, A completely machined part is formed that is continuous without any breaks in the tube axis direction and has no accumulation of air or the like between the inner and outer tubes, thereby achieving mechanical close contact between the inner and outer tubes.

As for the cutting margin in the method of the present invention, a part of the fixing fitting (81) is placed on the end of the inner tube (23) in order to prevent the rubber hollow body (9) from protruding on the inlet side of the tube expansion jig. As mentioned above, the inner tube should be made slightly longer than the outer tube, but only this longer part is the cutting margin.As this length is about 20 shoes, it is sufficient, so cut it down. As described above, in the method of the present invention, the cutting margin is greatly reduced compared to the conventional cold drawing method and hydraulic pipe expansion method, so it is much more advantageous in terms of yield.

Furthermore, in the method of the present invention, the accumulation of impurities such as air between the inner and outer tubes can be completely eliminated, so that the risk of peeling is also eliminated.

Also, from the viewpoint of conut, the pipe expansion jig of the present invention is much cheaper than a large drawing machine, and does not require the troublesome work of moving to a place exclusively for water pressure, as in the hydraulic pipe expansion method. Since the pipe expansion operation can be carried out immediately at the assembly point without having to do the process, it has a significant advantage over the conventional method in terms of efficiency.

It should be noted that the method of the present invention can be similarly applied to the production of double-walled steel pipes of any size and made of two materials by adjusting the size of the pipe expansion jig, and the effectiveness may be limited depending on the type of steel pipe to be used. There's no way I'll be able to do it.

<Effect of the invention> Dimensions: 245 shoes φX12. Om thickness (outer tube 1000 inner tube 2. (II) In the method of the present invention, the inner tube is first fitted to the outer tube with a length of 20 mm, and then the end of the inner tube is fitted with a length of 80 mm.
121 tube expansion jig was set. In the first pipe expansion, the part 60011 from the end is the fully machined part, and then the jig is moved 400 feet ahead so that the weight of the fully machined part is 200M, and the second pipe expansion is carried out in the same procedure. Do it.

By repeating this process, the pipe is expanded one after another until it reaches the other end. On the outlet side, a dummy material for the inner pipe was used to expand the pipe.

The 72:double element tubes obtained by the above-mentioned method of the present invention and the conventional method were prepared under exactly the same conditions, that is, after heating to 125 (l)
``Seamless Kutsurad snow was obtained by stretching and rolling in a rag mill.

The results obtained from the above test are as follows.

■ Yield: In the hydraulic pipe expansion method, the cutting margin of the inner pipe is 90%.
wX, whereas it was 20M in the method of the present invention, which was reduced to 4.5 in the method of the present invention compared to the conventional method.

■ Workability: In the hydraulic pipe expansion method, it was necessary to move from the double pipe assembly site to a special place with high-pressure equipment for hydraulic expansion, which lowered work efficiency, but with the method of the present invention, the double pipe expansion method Since it was possible to immediately expand the pipe using a pipe expansion jig at the pipe assembly site, work efficiency was greatly improved compared to the hydraulic pipe expansion method VC.

■ Quality: In the hydraulic pipe expansion method, peeling after stretching and rolling is 1
This occurred at a frequency of ~8%, but in the method of the present invention, there was no occurrence of peeling and a high quality seamless cladding could be obtained.

As is clear from the above explanation, the method for manufacturing seamless kutsurado panels of the present invention has no restrictions on the applicable size or material, and has advantages over conventional methods in terms of yield, work efficiency, and cost. Moreover, since the expansion process is applied to prevent the accumulation of air between the inner and outer pipes of the double-layered pipe, there is no risk of peeling. It can be said to be of great practical value in the production of clad pipes.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a tube expansion jig set at one end of the inner tube inserted into the outer tube, and is a longitudinal side view, and Figure 2 is the flammable sealed hollow body of the tube expansion jig shown in Figure 1. This is an explanatory diagram showing a state in which the inner pipe has been expanded by applying hydraulic pressure to the inner tube, and is a vertical side view. Figure 3 is a vertical front view explaining the structure of the flexible steel rib. Figure 4 is a back-alignment 1 metal fitting. FIG. 1: Outer pipe, 2: Inner pipe, 3: Tube expansion jig, 4/: Central outlet, 4-way inlet, 5: Through hole, 6: 8 rod, 71.7: Fixing metal fittings, 8/, 8J: Back 1 metal fitting, 9: Flexible sealed hollow body, 10: Burnable NuchitVVpu, 11: Leaf spring, 12: Piece, 13: Bolt, 14: Connecting part, 15/
, 15 Coni step surface, 16: Lubricating 1st 1 Fig. 1 Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] (1) Insert an inner tube made of composite material or base material into an outer tube made of base material or composite material, and insert a tube expansion jig having a flexible sealed hollow body filled with fluid into the inner tube. The processing operation of inserting the hollow body and expanding it by applying pressure to the internal fluid to expand the tube is performed in order from one end to the other end so that the completely processed part continues with an appropriate weight. A double raw tube with the base material and composite material in close contact with each other is obtained by this method, and after seal welding the base material and composite material at both ends of this double raw tube, this is heated to a predetermined temperature and hot-stretched and rolled. A method for manufacturing a seamless clad pipe, characterized by: