JPS60221167A - Production of heat-insulating composite pipe by two-stage casting - Google Patents

Abstract

PURPOSE:To improve mechanical strength and operability by casting a molten metal for forming an outside layer into a centrifugal casting mold through one aperture thereof as the 1st stage and casting a molten metal for forming an inside layer into said mold through the other aperture as the 2nd stage. CONSTITUTION:A cylindrical core material P consisting of heat insulating fibers P3 are disposed between an outside core pipe P1 and a circular core pipe P2 having plural gas vent holes. These pipes and core material are grapsed by means of a 1st stage side ring and a 2nd stage side ring 42 and are fixed to the casting mold 1. The molten metal M1 for the outside layer is cast from a 1st stage side hopper 31 into a molten metal pool A1 while the mold 1 is rotated. The molten metal M1 is filled in a space C by which the outside layer is formed. The molten metal M2 for the inside layer is then cast therein from a second stage side hopper 32 and is filled in a space B, by which the inside layer is formed. Mixing of the molten metals M2 and M1 for the inside and outside layers is obviated and the change in the volume of the alloy components in the inside layer of the composite pipe is prevented by the above-mentioned method. Since the inside layer is cast before the formation of solid solution of the outside layer, the mechanical strength and operability are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a heat-insulating composite pipe having a three-layer structure in which the middle layer of the pipe wall is made of heat-insulating fibers, and the outer and inner layers are made of different metals.

In steelworks, the transport rolls used to transport high-temperature heating materials such as slabs have a three-layer structure consisting of an intermediate layer of insulating fiber, an outer layer of heat-resistant steel, and an inner layer of cast iron. The roll body is made of a thermally insulated composite pipe.

The reason for this is that heat-resistant steel, which has excellent heat resistance, is suitable as a component of the outer layer that comes into direct contact with high-temperature heating materials such as slabs, and it is suitable for the inner layer, which requires strength, because it has high strength and is also economical. This is because cast iron is suitable. This is also because it is necessary to provide a layer of heat insulating fibers as the intermediate layer in order to suppress heat flow in the thickness direction of the tube.

As shown in Fig. 4, a method for manufacturing a heat-insulating composite tube used in such a conveyor roll body is an outer core tube (p+ )
A cylindrical core material (P) consisting of an inner core tube (P2) and heat insulating fibers (P3) filled in the gap between the two core tubes is placed in a centrifugal casting mold (1). Molten metal for forming the outer layer (hereinafter referred to as
First, the molten metal for forming the inner layer (hereinafter referred to as the molten metal for the inner layer) is cast to fill the space (C) around the cylindrical core material (P) to form the outer layer. There is a method in which an inner layer is formed inside a cylindrical core material (P) by casting. In this method, the molten metal for the outer layer and the molten metal for the inner layer are cast from the same casting hopper (31).

In such a method, since the molten metal for the outer layer and the molten metal for the inner layer are cast from the same casting hopper (31'), when the molten metal for the inner layer is poured, the molten metal for the outer layer remaining in the sump (A) There was a problem that the molten metal for the inner layer newly introduced into the sump (A>) was mixed, and the molten metal formed could not have the desired alloy composition. The molten metal for the outer layer near the cylindrical core material (P) solidifies into the container between the time when the inner layer is formed and the inner layer begins to form. As a result, only insulated composite pipes with low mechanical strength could be manufactured.Furthermore, due to the above-mentioned circumstances, after the outer layer was formed, the molten metal for the inner layer was immediately cast to form the inner layer. Although the molten metal for the outer layer and the molten metal for the inner layer must be poured into the same casting hopper (31'
), the workability was extremely poor.

The present invention has been made in view of the above circumstances, and its purpose is to prevent the change in the alloy composition of the inner layer when manufacturing a heat-insulating composite pipe in which the inner and outer layers are formed of alloys with different compositions. It is an object of the present invention to provide a method by which an insulating composite pipe with high mechanical strength can be manufactured, and which has extremely good workability.

The method for producing an insulated composite pipe by two-stage casting according to the present invention is to produce a three-layer insulated composite pipe by centrifugal casting, in which the middle layer of the pipe wall is made of insulating fibers, and the outer and inner layers are made of different metals. In the manufacturing method, the molten metal for forming the outer layer is poured as a first stage from a casting hopper provided at one opening of the centrifugal casting mold, and the molten metal is poured into the casting hopper provided at the other opening of the centrifugal casting mold. The hopper is characterized by the fact that the molten metal for forming the inner layer is poured into the second stage.

Hereinafter, the method of the present invention will be explained in detail with reference to the accompanying drawings.

Fig. 1 is a schematic vertical cross-sectional view of a casting apparatus used to carry out the method of the present invention, Fig. 2 is a right side view thereof, and Fig. 3 is a
It is a sectional view taken along the line -■. In addition, in FIG. 2 and FIG. 3, the casting hopper is not illustrated for clarity.

In the figure, (1) is a cylindrical centrifugal casting mold (hereinafter simply referred to as the mold), (21) is a donut-shaped single-stage end plate with a casting hole (21a) in the center, and (22) is a mold for centrifugal casting in the center. It is a donut-shaped two-stage side end plate having a casting hole (22a). The opening on the first stage side (the left side in Fig. 1) of the mold (1) is closed except for the casting hole (21a) by fitting the first stage side end plate (21), and The opening on the second stage side (the right side in FIG. 1) of 1) is closed except for the casting hole (22a) by fitting the second stage side end plate (22). The casting hole (21a) is configured to allow viewing of the lower end opening of the first-stage hopper (31) used for casting the molten metal (Ml) for the outer layer, and the casting hole (22a) , the lower end opening of the second hopper (32) used for casting the molten metal (M2) for the inner layer is visible.

Inside the mold (1), which is closed leaving the casting holes (21a) and (22a) as described above, there is an outer core tube (p+) and an inner core provided with a plurality of holes for degassing, etc. Pipe (P
2) and the insulating fibers (
A cylindrical core material (P) consisting of a cylindrical core material (P3), and a single-stage side ring (
41) and the second stage side ring (42) are housed therein.

The first stage ring (41) is a donut-shaped ring having an outer diameter corresponding to the outer diameter of the cylindrical core material (P), and is attached to the mold (1) by the hanging bolts (51) (51).
It is suspended coaxially in the air. By arranging the first-stage ring (41) in the mold (1) in this way, a first-stage sump (AI) is formed between the first-stage ring (41) and the first-stage end plate (21). is formed.

On the other hand, the second-stage side ring (42) is a ring whose outer diameter corresponds to the inner diameter of the mold (1), and the inner diameter of the second-stage side is slightly larger to form the second-stage side sump (A,). The diameter has been expanded.

The second stage side ring (42) is fitted inside the mold (1) and is fixed to the second stage side end plate (22) by fixing bolts (52) (52). There is.

As mentioned above, the cylindrical core material (P) is held between the first-stage peeling ring (41) and the second-stage side ring (42), and the outer side of the cylindrical core material (P) is A space (C) is formed between the mold (1) and the cylindrical core material (P
) A space (B) is formed inside the space (B).

Next, a case will be described in which a heat insulating composite pipe whose inner and outer layers are made of different alloys is manufactured using the above-mentioned casting apparatus.

First, while rotating the mold (1) about its axis, the molten metal (Ml) for the outer layer is poured from the single-stage stripping hopper (31) into the first-stage side sump (A+). The cast molten metal (Ml) for the outer layer is introduced into the space (C) along the inner surface of the mold (1) because the first-stage side sump (A,) communicates with the space (C). become. And the space (C) is the molten metal for the outer layer (M,)
The outer layer is formed. Thereafter, the molten metal for the inner layer (M2) is poured from the second stage side hopper (32) into the second stage side sump (Az). Molten metal for the inner layer (M2)
is introduced into the space (B) along the inner surface of the second-stage side ring (42) and the cylindrical core (P) because the second-stage side water reservoir (A2) communicates with the space CB). and a cylindrical core material (
An inner layer is formed inside P).

When manufacturing an insulated composite pipe in this way, the first-stage side sump (A,) stores the molten metal for the outer layer (Ml), and the second-stage side sump section (Ai) stores the molten metal for the inner layer (M2). ) are provided separately, so after forming the outer layer, the molten metal for the inner layer (M
Even at the time of casting 2), the molten metal for the outer layer (Ml) and the molten metal for the inner layer (M2) are not mixed. Therefore, the alloy composition of the inner layer of the heat-insulating composite pipe is not changed, and the desired result can be obtained. In addition, the molten metal (Ml) for the outer layer is stripped in one stage using a hopper (31
) and pour the molten metal (M2) for the inner layer into the second-stage side hopper (3).
Since the casting starts from step 2), the molten metal (M2) for the inner layer can be quickly cast after the outer layer is formed, and the workability is extremely good. Therefore, the molten metal for the outer layer (Ml
), the outer layer molten metal (M
, ) is not completely dissolved into a solid solution, the inner layer molten metal (M2)
is quickly cast, and both molten metals are melted together near the cylindrical core material (P), thereby improving the mechanical properties of the heat-insulating composite pipe.

This method of the present invention is applicable only when producing a heat-insulating composite pipe for a conveyor roll, in which the outside of a cylindrical core material filled with heat-insulating fibers is cast with heat-resistant steel, and the inside is cast with cast iron. However, it can be applied to the production of various types of heat-insulating composite pipes in which the outer layer and inner layer have different components.

Note that even when manufacturing a heat insulating composite pipe in which the outer layer and the inner layer have the same components, the method of the present invention can be used to form the outer layer and the inner layer to produce the heat insulating composite pipe.

Needless to say, it can be done.

As detailed above, when manufacturing an insulated composite pipe with different compositions in the inner and outer layers using the method of the present invention, the molten metal for forming the outer layer is poured from the one-stage casting hopper provided at one opening of the centrifugal casting mold. Since the molten metal for forming the inner layer is poured from the second-stage casting hopper provided at the other opening, the molten metal for forming the outer layer and the molten metal for forming the inner layer are not mixed, and the molten metal for forming the inner layer is not mixed. There is no change in the alloy composition of the inner layer. In addition, since the molten metal for forming the inner layer can be cast in a state where the molten metal for forming the outer layer is not completely solidified, both molten metals are melted together near the cylindrical core material, improving the mechanical properties of the heat-insulating composite pipe. I can do it. Furthermore, the present invention provides extremely good workability during casting, and thus provides an extremely effective means for manufacturing a heat-insulating composite pipe whose inner and outer layers have different compositions.

[Brief explanation of drawings]

Fig. 1 is a schematic vertical cross-sectional view showing a casting apparatus used to carry out the method of the present invention, Fig. 2 is a right side view thereof, Fig. 3 is a sectional view taken along line mm in Fig. 1, and Fig. 4. FIG. 1 is a schematic cross-sectional view showing a conventional casting device. 1: Mold for centrifugal force casting, 21 D, first stage side end plate, 22: Second stage side end plate, 31 D, first stage side hopper, 32: Second stage side hopper, 4
1 1st stage side ring, 42: 2nd stage side IJ link, A1 2nd stage side sump part, A: 2nd stage side sump part, P: Cylindrical 4 large core materials,
P,: heat insulating fiber, MI=molten metal for forming the outer layer, M2: molten metal for forming the inner layer. Agent Patent Attorney Miyazaki Shinshiki Department Figure 1 Figure 2 Figure 2

Claims (1)

[Claims] +1) In a method for manufacturing a three-layer thermally insulated composite pipe by centrifugal force casting, in which the middle layer of the pipe wall is made of insulating fibers and the outer and inner layers are made of different metals, one opening of the centrifugal force casting mold is The molten metal for forming the outer layer is poured into the first stage from the casting hopper installed at the opening of the centrifugal casting mold, and the molten metal for forming the inner layer is poured into the second stage from the casting hopper installed at the other opening of the centrifugal casting mold. A method for manufacturing insulated composite pipes by two-stage casting, characterized by casting as