JPH0471742A - Manufacture of tube having complicated section hole - Google Patents

Abstract

PURPOSE:To easily manufacture a tube having a hole complicated in sectional form by compacting a previously worked mandrel as a core then melting the mandrel. CONSTITUTION:The mandrel 21 having the same sectional form as the sectional form of a desired hole 1 is made of low melting point alloy in advance, this is inserted into another metal tube 02 and compressed by an electromagnetic forming machine in the radial direction, therefore, the metal tube 02 is reduced uniformly along the form of the mandrel 21 and the sectional form of the hole 1 is the same form as the sectional form of the mandrel 21. Then, when this is heated, since the mandrel 21 is made of low melting alloy, it is melted away easily, the tube 2 having the hole 1 complicated in sectional form can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a heat exchanger tube having a complicated hole such as a star shape in cross section and used in a condenser of an underwater vehicle or the like.

[Prior Art] Conventionally, the method of manufacturing high-strength A1 alloy (e.g., 2219Al) heat exchanger tubes having holes with complex cross-sectional shapes, such as star-shaped holes, has a low plastic deformability due to high deformation resistance during extrusion or drawing. It was impractical. Therefore, the only option was to use the wire cutting method (a type of electric discharge machining method). FIG. 4 shows an example of a method of manufacturing a long heat exchanger tube with a large star-shaped cross section using the conventional wire cutting method.
A pilot hole 38 is previously drilled in the high-strength 11 alloy plate 33, and the wire 34 is passed through the hole 38.
A current is caused to flow between the electrodes 36, and the wire force is used to cut the wire by utilizing the discharge phenomenon.

Star-shaped machining is performed by moving the electrode 36 of the wire cutting device 5 under computer control in the XY force direction to cut the wire-cut hole 3.
7.

[Problem to be solved by the invention]

The above-mentioned conventional method for manufacturing a large pipe with a complex cross section has the following problems to be solved.

That is, the method of machining holes by wire cutting has the disadvantage that the machining process requires a long time (which results in high costs).

[Means to solve the problem]

As a means of solving the above-mentioned problems, the present invention is a method for producing a tube having a star-shaped or other complex cross-sectional shape, in which a mandrel made of a low melting point alloy and having the same cross-sectional shape as the desired hole is drawn. The mandrel was inserted into a relatively thin metal tube prepared separately, and the mandrel was held in the center of an electromagnetic forming machine capable of generating electromagnetic compressive force in the center, and the electromagnetic forming machine was activated to shape the metal tube into a radius. The object of the present invention is to provide a method for manufacturing a large pipe with a complex cross-section, which is characterized in that the mandrel is electromagnetically compressed in the same direction and then removed by heating and melting to obtain a pipe with a hole having a complicated cross-section.

(Function) Since the present invention is constructed as described above, it has the following function.

That is, a mandrel with the same cross-sectional shape as the desired hole is made in advance from a low-melting point alloy, and this is inserted into another metal tube and compressed in the radial direction by an electromagnetic forming machine, so that the metal tube has the shape of the mandrel. The cross-sectional shape of the hole becomes the same as the cross-sectional shape of the mandrel. Next, when this is heated, since the mandrel is a low melting point metal, the melt is easily removed, and a tube having holes with a complicated cross-sectional shape is obtained.

[Example] An example of the method of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 3 shows a Fuiri A1 alloy (for example, 2219A1
Figures 1 and 2 show an example of a manufacturing method thereof, with Figure 1 being a perspective view and Figure 2 a schematic diagram showing the manufacturing process.

First, as shown in FIG. 1, a mandrel 21 of a low melting point alloy (e.g., PB-Sn alloy) is manufactured as a long rod by extrusion or drawing, and then a high-strength A1 alloy tube 02 is prepared in advance.
Insert inside.

Next, as shown in FIG. 2, the high-strength 11 alloy tube 02 is inserted into the magnetic flux concentrator 28 of the electromagnetic forming machine 10, the voltage of the negative side power source 30 is increased by the transformer 31, and the rectifier 23 converts the voltage into DC. The low melting point alloy mandrel 21 is charged with instantaneous force by the switch 29 and the A1 alloy tube 02 is placed therein.
Compressive deformation is performed from the outside by electromagnetic compressive force 27 that is instantaneously generated between. In this way, while feeding at a predetermined pitch, the long high-strength 11 alloy tube 02 is made into a heat exchanger tube with a star-shaped hole 1. Next, after completing the forming, the low melting point alloy mandrel 21 placed in the high strength A1 alloy tube 02 is heated to around 150°C.
By melting, a high-strength At alloy heat exchanger tube 2 as shown in FIG. 3 is obtained.

〔Effect of the invention〕

Since the present invention is configured as described above, it has the following effects.

In other words, a hole with a complicated cross-sectional shape in a tube is obtained by compression molding a pre-processed mandrel as a core material and then melting the mandrel instead of using cutting or electric discharge machining, so that a tube with a hole of a desired cross-sectional shape can be obtained. can be easily obtained. In addition, since the mandrel is immediately machined to the hole accuracy, highly accurate holes can be easily and economically obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main steps according to an embodiment of the method of the present invention, FIG. 2 is a schematic diagram of a tube being manufactured by the method of the above embodiment, and FIG. FIG. 4 is a three-dimensional illustration of the conventional method. ■...star-shaped hole, 2...high-power old alloy heat exchanger tube lO... with magnetic forming machine, 21...mandrel.

Claims (1)

[Claims] In a method of manufacturing a tube having a hole with a star-shaped or other complex cross-sectional shape, a mandrel made of a low-melting point alloy with the same cross-sectional shape as the desired hole is manufactured by drawing, and a relatively After inserting the mandrel into a thin metal tube, the mandrel is held at the center of an electromagnetic forming machine capable of generating electromagnetic compressive force at the center, and after operating the electromagnetic forming machine to electromagnetically compress the metal tube in the radial direction, the mandrel is A method for producing a tube with a complex cross-section and a hole, the method comprising heating and melting and removing the tube to obtain a tube with a hole in a complex cross-section.