JPS58176029A - Working of heat pipe container - Google Patents

Abstract

PURPOSE:To make a hole formed at the bottom end of a heat pipe container by drawing uniform by providing a pinlike core of specified diameter at the center of spherical face or conical face of a rotary die having a spherical face or a conical face. CONSTITUTION:A pinlike core 8 of specified diameter is provided at the center of spherical face of a spherical die 6. When the end of a metallic pipe 4 is pushed into the spherical part of the die 6 while rotating the spherical die 6, the end of the metallic pipe 4 is softened by frictional heat, deformed to a spherical form and comes into contact with the core 8. When the metallic pipe 4 is pushed further, the thickness of the spherical part of the metallic pipe increases. However, no further deformation is caused in the part of core. Drawing of the end part is completed by pulling back the pipe to separate from the die 6 after pushing the metallic pipe 4 by specified amount. Thus, a hole of uniform diameter is always formed at the end of the metallic pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for processing a heat pipe container, and particularly to a method for processing an end portion of a heat pipe container.

Heat pipes are widely used, for example, as containers for heat exchange media in refrigerators and the like. That is, a heat exchange medium such as Freon is sealed inside the heat pipe container, and is used in refrigerators and the like to create a temperature difference between both ends of the container.

A conventional one-pipe container generally consists of a bottom end 1, a cylindrical part 2, and a sealed end 3 which is closed after the medium is filled in, as shown in FIG. The structure of the bottom end portion 1 is usually such that the cover member 1' is entirely attached to the end of the metal cylindrical portion 2 by brazing or welding (as shown in the figure).

However, in order to simplify the manufacturing process and improve reliability against leakage, a method has been developed in which the bottom end is drawn using a spherical die and then welded or the like is performed.

FIG. 2 illustrates such a drawing process. That is, by pressing the metal pipe 4 in the direction of the arrow against the rotary die 6 having a spherical surface, the tip thereof is heated by frictional heat and shaped by applying a constant pushing amount. FIG. 3 shows the shape of the end of the heat pipe container that has been smoothed in this manner. The diameter of the hole left at the tip varies depending on the amount of pushing, the pushing speed, variations in the wall thickness of the metal pipe 4, etc. This hole at the tip is welded using TIG or plasma arc, and for this welding, the optimal welding conditions must be met depending on the outer diameter and wall thickness of the metal tube, such as current, current application time, and hole diameter of the welded part. However, it is not possible to produce a uniform bottom end of the heat pipe container due to variations in the diameter of the hole at the tip produced by the conventional method. In other words, if the hole diameter is too large, the metal around the hole melted by the arc will not be able to close it, and if the hole is too small, only the outside of the tip will be fused during the initial stage of arc discharge. The hole is partially blocked by the blocked portion 4', and the subsequent arc does not reach the inside of the hole but flows to the periphery and the heat is dispersed, resulting in a depression 7 inside the tip as shown in FIG. The result remains.

If the heat pipe container has a bottom end shouldering the recess 7, the working fluid in the recess will be overheated compared to the other parts, especially when a medium, that is, a working fluid, is sealed by the boiling method. , it becomes easy to form boiling nuclei, which causes bumping when the hydraulic fluid is sealed.

Furthermore, even after the heat pipe is formed, such depressions cannot be left as they are weak points in terms of strength against internal pressure1.If a uniform planned hole diameter can be obtained, welding conditions should be adjusted accordingly. This decision can be made and these inconveniences can be resolved.

The purpose of the present invention is to eliminate the variation in residual hole diameter in drawing the bottom end of a heat pipe container using a rotating spherical die, and to provide a method for processing the bottom end of a heat pipe having a uniform 6-hole diameter. The purpose of this is to provide a heat pipe with no defects at the bottom end.

According to the present invention, a predetermined outer diameter is set at the center of the spherical or conical surface of a rotary die having a spherical or conical surface in order to make the holes formed at the bottom end of the heat pipe container uniform by drawing. The above object is achieved by providing a bottle-shaped core having the following properties.

The invention will now be described in detail with reference to FIGS. 4 and 5.

FIG. 4 shows a spherical die 6 according to the invention. A pin-shaped core 8 having a predetermined outer diameter is provided at the center of the spherical portion. The drawing process is performed in the following steps. Rotary chuck (not shown)
When the end of the metal tube 4 is pushed into the spherical part of the die while rotating the spherical die 6 held by the holder, the end of the metal tube softens due to frictional heat, deforms into a spherical shape as the pushing progresses, and finally comes into contact with the core 8 (Fig. 5). If the metal tube is pushed forward even after contact, the thickness of the spherical portion of the metal tube will increase, but the core portion will not deform any further. After the metal tube 4 is pushed in a predetermined amount, it is pulled back away from the die 6, thereby completing the drawing process of the end. Thus, at the end of the metal tube that has been squeezed into a spherical shape 9 and pressurized 2',
A hole with a uniform diameter is always formed regardless of the amount of pushing or the variation in the wall thickness of the entire tube.The shape of the machined surface of the die 6 is not limited to a spherical shape, but may be tapered or a combination thereof. The shape of the core 8 may be a cylinder with a constant diameter or a tapered shape.

Since the spherical end of the metal tube drawn by the die of the present invention has a uniform hole diameter in the center, a good weld is always obtained by TIG or plasma arc welding. For this reason, there are no dents that can cause bumping when filling the working fluid using the boiling method, and there are no problems with strength due to the internal pressure in the gap when the heat pipe is operated at high temperatures. The drawing process using a spherical die with a core according to the present invention is an extremely excellent method for processing the bottom end of a heat vibrator container.

[Brief explanation of the drawing]

Figure 1 is a vertical cross-sectional view of a conventional heat pipe container, Figure 2 is a vertical cross-sectional view of the edged metal tube end, which is an improved version of the conventional heat pipe, and Figure 3 is a conventional spherical surface for rotary drawing. FIGS. 4 and 5 are longitudinal sectional views showing an embodiment of a spherical die with a core according to the present invention and a processing method using the same.

Claims (1)

[Claims] In a method of processing a heat pipe container by inserting the end portion of a metal tube into a rotating die having a spherical or conical processing surface and drawing it, the center of the processing surface where the metal tube hits the top of the rotating die. A heat pipe container characterized in that a pin-shaped core is provided in the metal pipe, a hole corresponding to the core is left at the end of the metal pipe after drawing, and the hole is then closed by welding. Processing method.