JPH10277629A - Manufacture of fine inner diametered metallic pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a long size fine inner diametered metallic pipe excellent in precision without applying a mandrel and a floating plug by forming a compound material from a metallic pipe with a material nonreactive to the metallic pipe inserted in the metallic pipe and then removing the inserted material by liquefying, gasification, combustion or dissolution after reducing the diameter of the metallic pipe. SOLUTION: A compound material 4 is formed by inserting or packing a fine hole forming material 3 nonreactive to a metallic pipe 2 into the interior of the metallic pipe 2. This compound material 4 is subjected to diameter reducing with a die 5 and is formed into a diameter reduced compound material 6. After that out of the diameter reduced compound material 6, the fine hole forming material 3 is removed by liquefying, gasification, combustion or dissolution, and the fine inner diametered metallic body is manufactured. As to the fine hole forming material, thermal plastic plastics, metals of low melting point, an alkari soluble material and the like are cited. Further, another method is mentioned as well that a metallic pipe 2 filled with water is subjected to diameter reducing below the freezing point and then the ice in the interior is removed by melting under the normal temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a small-diameter metal pipe, and more particularly to a method for manufacturing a small-diameter metal pipe without using a mandrel and a floating plug.

[0002]

2. Description of the Related Art When a metal pipe having a small inside diameter (hereinafter, referred to as a small inside diameter metal pipe) is manufactured by drawing, there are a drawing method using a mandrel and a drawing method using a floating plug.

In a drawing method using a mandrel, a material (for example, a piano wire, a tungsten wire, or the like) having higher strength or hardness than a pipe to be processed is inserted as a mandrel into the inside of the pipe to be processed, and then the pipe to be processed is connected to the pipe. The mandrel and the mandrel are integrated and passed through a die hole to perform diameter reduction processing. After the diameter reduction processing, only the mandrel is taken out to obtain a small inner diameter metal tube.

In a drawing method using a floating plug, a floating plug having a diameter smaller than the diameter of the pipe to be processed is inserted into the pipe to be processed, and then the floating plug is fixed so as to be always positioned within the die surface. At the same time, the pipe material to be processed is passed through a die hole to reduce the diameter, thereby obtaining a metal pipe having a small inner diameter.

[0005]

However, in the case of a drawing method using a mandrel, the mandrel is too thin, so that there is a problem in that a general mandrel where one end of the mandrel is fixed is broken due to insufficient strength. Further, since it is necessary to insert a very fine mandrel into the pipe to be processed, there is a problem that workability is impaired and manufacturability is not very good. Furthermore, when manufacturing a long narrow inner diameter metal tube, a long mandrel is required, and thus there is a problem that it is difficult to take out the mandrel after the diameter reduction processing. Furthermore, since mandrels of various diameters are required in accordance with the drawing path, there is a problem that the manufacturing cost is increased.

Further, in the case of the drawing method using the floating plug, it is difficult to hold the floating plug in the die surface, so that it is not very suitable for manufacturing a metal tube having a small inner diameter.

Accordingly, the present invention has been made to solve the above-mentioned problem, and a small-diameter metal tube capable of easily and inexpensively manufacturing a long, high-precision small-diameter metal tube without using a mandrel and a floating plug. It is to provide a method for manufacturing a tube.

[0008]

According to a first aspect of the present invention, a composite material is prepared by inserting or filling a pore-forming substance which does not react with the metal tube into a metal tube. After forming and reducing the diameter of the composite material to form a reduced-diameter composite material, the substance is removed from the reduced-diameter composite material by liquefaction, gasification, combustion, or dissolution.

A second aspect of the present invention is the method for producing a small-diameter metal tube according to the first aspect, wherein the substance is a thermoplastic, a low-melting metal, or an alkali-soluble metal.

According to a third aspect of the present invention, the inside of a metal tube is filled with water, the metal tube is reduced in diameter below freezing to form a reduced metal tube, and then the ice inside the reduced metal tube is formed. Is dissolved and removed at room temperature.

According to the above construction, a composite material is formed by inserting or filling a pore-forming substance which does not react with the metal tube into the metal tube, and the composite material is subjected to diameter reduction processing. After the reduced-diameter composite material is formed, the substance is liquefied, gasified, burned, or dissolved and removed from the reduced-diameter composite material. Therefore, a long, high-precision fine material is used without using a mandrel and a floating plug. The inner diameter metal tube can be manufactured easily and at low cost.

[0012]

Embodiments of the present invention will be described below.

FIG. 1 is a schematic view showing a method for manufacturing a small-diameter metal pipe according to the present invention. FIG. 2 is a cross-sectional view of a composite material for manufacturing the small-diameter metal tube of the present invention. FIG. 2A shows a longitudinal sectional view, and FIG. 2B shows a transverse sectional view.

[0014] As shown in FIGS. 1 and 2, the manufacturing method of small inside diameter metal tube of the present invention, first, a metal tube of inside diameter D ₁ 2
A material (substance) 3 for forming pores which does not react with the metal tube 2 is inserted or filled into the inside of the composite material 4.

Next, the composite material 4 is reduced in diameter by a die 5 to form a reduced-diameter composite material 6 having an inner diameter of D ₂ .

Thereafter, the substance 3 for forming pores is liquefied, gasified, burned, or dissolved from the reduced-diameter composite material 6 to produce a small-diameter metal tube (not shown).

The constituent material of the metal tube 2 is not particularly limited, and examples thereof include copper and steel, and the method of manufacturing the metal tube 2 is not particularly limited.

As the combination of the metal tube 2 and the pore-forming substance 3, the pore-forming substance 3 is liquefied, gasified, burned, or compressed from the reduced-diameter composite material 6 obtained by reducing the diameter of the composite material 4. There is no particular limitation as long as the metal tube 2 can be dissolved. For example, a combination of the metal tube 2 and a substance that is liquefied or gasified at a temperature lower than the melting point of the metal tube 2 and flows out from the metal tube 2; And combinations of substances that can be chemically dissolved with the metal tube 2.

As a combination of the metal tube 2 and a substance which is liquefied or gasified at a temperature lower than the melting point of the metal tube 2 and flows out of the metal tube 2, for example, a Cu tube and a thermoplastic (polyester or the like) are heated. And gasification of thermoplastics. At this time, by using a high-purity thermoplastic, it is possible to substantially eliminate the thermoplastic resin residue remaining in the small-diameter metal tube.

As a combination of the metal tube 2 and a substance which is burned and disappears from the metal tube 2, for example, there is a combination in which a Cu tube and a low melting metal such as solder are heated to burn the low melting metal.

Examples of the combination of a substance that can be chemically dissolved in the metal pipe 2 include a combination in which a steel pipe and Al are dissolved in alkali and only Al is dissolved.

FIG. 3 shows an example of a method for producing a composite material for producing a metal tube having a small inner diameter according to the present invention.

As shown in FIG. 3, first, a metal tube 12 is arranged in a cylindrical extrusion container 11, a die 13 is provided at one end in the extrusion device 11, and a pusher is pressed at the other end in the extrusion device 11. Piston 14 consisting of plate 14a and stem 14b
Is provided. A die holding member 19 is provided outside the die 13.

Next, the extruder 11 is filled with the molten polyethylene 15, and hot liquid pressure extrusion is performed using the molten polyethylene 15 as a pressure medium. After this, the reduced diameter metal tube 16
Is cooled to produce a composite material 18 in which polyethylene 17 is filled in a reduced-diameter metal tube 16.

That is, according to the method for manufacturing a small-diameter metal tube of the present invention, the material for forming pores inserted or filled in the metal tube serves as a mandrel instead of not using the mandrel and the floating plug. It is possible to easily and inexpensively manufacture a long, high-precision small-diameter metal tube, which has been difficult to manufacture.

Next, another embodiment of the present invention will be described.

According to the method for producing a small-diameter metal tube of the present invention, a composite material is formed by inserting or filling a pore-forming substance that does not react with the metal tube into the metal tube, and reducing the diameter of the composite material. After forming the reduced-diameter composite material, the pore-forming substance is removed from the reduced-diameter composite material by liquefying, gasifying, burning, or dissolving.

The method of manufacturing a small-diameter metal tube according to the present embodiment is as follows. First, water is filled in a metal tube, and the metal tube is subjected to a diameter-reducing process under a freezing point such as in liquid nitrogen to reduce the diameter of the metal tube. To form

The water in the metal tube is frozen and becomes ice by the diameter reduction processing below the freezing point.

Thereafter, by leaving the reduced-diameter metal tube at room temperature, the ice inside the reduced-diameter metal tube is melted and removed from the reduced-diameter metal tube, and a small-diameter metal tube is obtained.

In the method of manufacturing a small-diameter metal tube according to the present embodiment, it is needless to say that the same function and effect as those of the present invention can be obtained. Since the step of removing the substance for forming pores from the (reduced-diameter composite material) is unnecessary, a metal tube having a small inner diameter can be manufactured at a lower cost, and the substance for forming pores inside the metal tube having a small inner diameter can be manufactured. A new function and effect is obtained in that there is no residue.

[0032]

First, polyethylene is filled in a Cu tube having an inner diameter of 10 mm formed by drawing using a floating plug, thereby forming a composite metal tube.

Next, the composite metal tube is subjected to drawing to form a reduced-diameter composite material having an inner diameter of 0.8 mm.

Thereafter, the reduced-diameter composite material is placed in a heating furnace at 400 ° C. in a nitrogen atmosphere, and polyethylene is gasified from the reduced-diameter composite material to produce a small-diameter metal tube.

The obtained small-diameter metal pipe had a good internal shape and had sufficient accuracy.

[0036]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) Instead of not using a mandrel and a floating plug, the material for forming pores inserted or filled in the metal tube plays the role of a mandrel, and therefore, it has been difficult to manufacture a long and accurate material. A high-thin-diameter metal tube can be easily and inexpensively manufactured.

(2) By using water as the pore-forming substance filled in the metal pipe, it is possible to obtain a small-diameter metal pipe having no pore-forming substance residue therein.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a method for producing a small-diameter metal tube of the present invention.

FIG. 2 is a cross-sectional view of a composite material for producing a small-diameter metal tube of the present invention.

FIG. 3 is an example of a method for producing a composite material for producing a small-diameter metal tube of the present invention.

[Description of Signs] 2 Metal tube 3 Pore forming substance (substance) 4 Composite material 6 Reduced diameter composite material

Claims (3)

[Claims] 1. A composite material is formed by inserting or filling a substance for forming pores that do not react with the metal tube into a metal tube to form a composite material. A method of manufacturing a metal tube having a small inner diameter, which comprises liquefying, gasifying, burning, or dissolving the substance and removing the substance from the reduced-diameter composite material after the formation. 2. The method according to claim 1, wherein the substance is a thermoplastic, a low-melting metal, or an alkali-soluble metal. 3. Filling the inside of a metal tube with water, subjecting the metal tube to a diameter reduction process below freezing to form a diameter reduced metal tube, and then melting the ice inside the diameter reduced metal tube at room temperature. A method for producing a metal tube having a small inner diameter, which comprises removing the metal tube.