JPS62131200A - Method of sealing heat pipe end - Google Patents

Abstract

PURPOSE:To seal an end of a heat pipe easily and surely by crushing a small diameter pipe section for sealing that is formed at the end section of a metal pipe by means of a die and a punch of a particular shape with a section of a certain dimension which is not crushed left at the tip end section of the pipe and joining by welding the section of the pipe that is not crushed. CONSTITUTION:One end of a metal pipe such as a copper pipe is sealed and on the other end a pipe section 11 of a small diameter is formed. Non-condensating gases such as air, etc. in the metal pipe 10 are exhausted and a specified working fluid is injected into the inside of the metal pipe 10. The end section 11 of the small diameter pipe is worked to crush it and make the inside faces contact each other with a section 12 of a specified dimension which is not crushed left at the tip end. The crushing work on the pipe end is carried out by pressing radially from outside with a die 13 which has a concave circular face of a specified shape and dimension and a punch the tip end of which is a truncated square pyramid. The metal pipe 10 which has undergone the crushing work is held up right, and the not crushed section 12 left on the end section of the small diameter pipe section 11 is heated to be melted and fused together. With this method, at both end sections in the crushed section where the curvature given by folding is largest has the largest degree of crushing, and as a result no opening caused by the springing back of the pipe material is given, making sure that the press-fusion is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a heat pipe by sealing the end of the pipe after injecting a working fluid.

Conventional Techniques As is well known, a heat pipe has a structure in which a non-condensable gas such as air is evacuated and then a condensable fluid such as water or ammonia is sealed as a working fluid. It is necessary to completely seal the end of the pipe to prevent air from entering or leaking of the working fluid, and therefore the conventional method of sealing the pipe end has generally been to use both crimping and welding. In that case, sealing of the end on the side where the working fluid is injected is necessary if the working fluid has already been injected into the metal tube and the internal pressure is below atmospheric pressure, and if heat is applied to the metal tube. Because there are special circumstances such as the working fluid evaporating and the internal pressure of the metal tube becoming higher than atmospheric pressure, special consideration needs to be taken, and conventional methods based on such requirements have been Japanese Patent Publication No. 51-271
No. 46, JP-A-52-23759, JP-A-53-51
556@, Japanese Patent Publication No. 56-24875, etc., various proposals have been made. Among these, the special public service No. 56-24875
The method in question is a method in which the crimping shape of the cylindrical short pipe section for injecting the working fluid is improved, and the compression is carried out so that the shape after compression becomes a semicircular cross section. The method of welding the tip is said to have the effect that welding can be easily and inexpensively performed.

Problems to be Solved by the Invention However, when crimping the end of a tube to seal it, all that is needed is to crush the cylindrical shape and fold it in two.
The method proposed in the above-mentioned Japanese Patent Publication No. 56-24875 seems to be characterized by squeezing so that the shape after crimping becomes a semicircular cross section, but in order to crimp into such a shape, it is necessary to As shown in FIGS. 7(A) to 7(C), a die-like receiver having a recess 1 with a semicircular cross section has a member 2 and a hemispherical or semicylindrical tip having a radius smaller than the radius of the recess 1. It seems necessary to press the cylindrical short tube portion 4 with a suppressing member 3 equivalent to a punch.

When such a crimping process is performed, both ends of the crimped tube P, which is formed into a semicircular cross section, are as shown in FIG. 7(B).
As shown in FIG. 2, the curvature becomes significantly large and the actual wall thickness becomes thicker than other parts, so springback tends to cause incomplete crimping and a slight opening is likely to occur.

In order to eliminate this inconvenience, it may be considered that both ends should be crushed more than the middle part, which has a small curvature.In the conventional method described above, as shown in FIG. 7(B), In a state where the center of curvature of 1 and the center of curvature formed at the tip of the suppressing part vi3 coincide, the pressing force applied to the crimped tube P becomes equal at all parts, but from that state, the pressing member 3 @ is pushed further. Even so, the distance between the inner surface of the recess 1 and the outward direction of the pressing member 3 does not increase at the portions corresponding to both ends of the compressed tube P to be crimped, so the amount of compression at both ends does not increase, and therefore the pressing member 3 There is a problem in that even if the amount of pushing is increased, the occurrence of the above-mentioned opening cannot be reliably prevented. In addition, in the above-mentioned method, the pressing member 3 whose tip end is hemispherical or semi-cylindrical is used to press the pipe, but when the pressing member 3 starts pushing the pipe P to be crimped, the center of the pressing member If the line is deviated from the center of the crimped tube P, the tip of the suppressing member 3 is hemispherical or semi-cylindrical, so the lateral component force generated by pressurization will rotate the crimped tube P. Otherwise, it was easy to move laterally, and as a result, there was a high possibility that the desired shape could not be squeezed and an opening would be formed. Furthermore, in the above-mentioned method of crimping to a semicircular cross section, the tip of the crimped part to the semicircular cross section is welded, and the welding produced at that time flows into the groove of the semicircular part. In order to do this, a considerable amount of the crimped part must be melted, and the melted droplets mainly flow into the groove, so the crimped part becomes shorter, and the opening (after cooling and solidification) becomes clogged. There was a risk that it would not work positively as a plug.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a method for easily and effectively sealing the end of a heat pipe.

Means for Solving the Problems In order to achieve the above object, the present invention forms a small diameter tube section for sealing at the end of a metal tube into which a working fluid is injected after exhausting a non-condensable gas. Then, when sealing the metal pipe by sealing the small diameter pipe part, the tip of the small diameter pipe part is sealed so that the outer surface is arcuate and a truncated quadrangular pyramid shaped recess is formed inside. A portion of the tft 11 with a predetermined size of the non-collapsed portion left is crushed by a die having a concave arc surface and a punch whose tip has a truncated quadrangular pyramid shape, and then the non-squeezed portion is melted and joined. This is the method to do so.

Accordingly, in the method of the present invention, the small diameter tube portion is crushed using a punch having a tip portion or a truncated square pyramid, and as a result, the tube is crimped so that a concave portion having an arcuate outer surface and a truncated quadrangular pyramid shape is formed inside. Therefore, the amount of collapse of the side edge of the concave portion along the axial direction of the small diameter tube portion is greater than that of the other portions, and as a result, springback at the portion where the curvature is greatest and the resulting opening Occurrence can be prevented. In addition, since the non-collapsed part is hollow and open, if we melt and join it, the droplets generated at that time will solidify as a plug that closes the opening, so it will be more securely closed. .

Example The present invention will be described in detail below.

In carrying out the present invention, first, the -h end of a metal tube 10 such as a copper tube, which is a container for the main body of the heat pipe, is sealed, and the other end of the metal tube 10 is sealed. As shown in FIG. 1, a small-diameter tube section 11 with a small diameter is formed at the end, and non-condensable waste such as air is exhausted from the inside of the metal tube 10 through the narrow-diameter tube section 11. , a predetermined working fluid is injected into the metal tube 10 . A portion of the small-diameter tube portion 11 with a non-collapsed portion 12 of a predetermined size remaining at its tip is subjected to crushing and crimping. As shown in FIG. 2, the small-diameter tube portion 11 is placed inside a die 13 having a concave arc surface, and a punch 14 whose tip end is in the shape of a truncated quadrangular pyramid, as shown in FIG.
This is done by pressing against the small diameter tube portion 11 from the outside in the radial direction. The die 13 used has a concave portion with a curvature equal to or less than the curvature of the outer circumferential surface of the small-diameter tube portion 11, and the tip of the punch 14 has a truncated pyramid shape that is aligned with the @ line of the small-diameter tube portion 11. The maximum width measured in a plane perpendicular to
The shape has a length equal to or longer than the diameter of the assembled diameter tube section 11 minus its wall thickness. When performing such processing, bond 1
Since the tip of 4 is flat, insert the punch 14 into the die 13.
Even if the center line of the punch 14 is slightly off the center of the small diameter tube section 11, the small diameter tube section 1
1 is crushed along a radial line passing through the center, so that abnormal deformation of the small diameter tube portion 11 does not occur. The crushed state by the die 13 and the bonder 14 is shown in FIG. 4. In this state, the slope of the truncated square pyramid formed at the tip of the punch 14 becomes parallel to the chord in the concave part of the die 13.
The distance 9 between the die 3 and the punch 14 at the open end of the recess (both ends of the crushed portion) is smaller than the distance at the intermediate portion, as shown in FIG. Both ends, where openings are likely to occur due to the bag, are more actively pressed into two folds. the result,
The metal tube 10 is crimped and sealed at the crushed portion of the small diameter tube portion 11. It is preferable that the punch 14 be located on the outside in the width direction (on the left side in FIG. 5) of the side surface of the punch 14 from the end of the hole 15 created by folding it in half in this way.
This allows the quadrangular truncated pyramidal portion at the tip of the punch 14 to be coupled with the above-mentioned dimensions, and as a result of squeezing, the small diameter tube portion 11
The entire inner surface of the product can be firmly adhered to.

The metal tube 10 that has been crushed as described above is stood vertically with the small diameter tube section 11 facing upward, and in this state, the non-collapsed portion 12 remaining at the tip of the small diameter tube section 11 is heated and melted. and join. In other words, weld. In that case, since the non-collapsed portion 12 remains in a cylindrical shape, the molten metal generated by heating fills the hollow portion, and the molten metal beyond the hollow portion becomes spherical above the collapsed portion. to solidify. Figure 6 is a diagram showing the state after crushing and welding as described above, and as shown here, in the above method, the crimped part remains as it is, and the molten metal due to welding on the tip side remains. The metal tube 10 is solidified into a plug, and the metal tube 10 is sealed by both the crimped portion and the welded portion.

Effects of the Invention As is clear from the above explanation, according to the method of the present invention, the small-diameter tube portion is crushed and crimped using a punch with a truncated quadrangular pyramid tip. The degree of crushing is greater at both ends where the associated curvature is greatest, and as a result, crimping can be achieved reliably without creating an opening due to springback, and the tip surface of the punch is flat, so Even if there is a slight misalignment between the axis of the punch and the center of the small-diameter tube, it is possible to crush the pipe into the desired shape, ensuring reliable crimping. Since the non-collapsed part left on the tip side of the part is melted and joined, the crimped part is not affected, and the molten metal generated by heating solidifies as a plug against the small diameter pipe part. Effects such as improved strength and durability of the sealed area can be obtained.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the small diameter tube provided at the end of the metal tube, Figure 2
The figure is a cross-sectional view showing the state at the start of crushing, Figure 3 is a perspective view showing the shape of the tip of the punch, Figure 4 is a cross-sectional view of the crushed state, and Figure 5 is a partially enlarged view showing the end of the crushed part. Figures 6 and 6 are front views showing the state in which the melting bonding process has been completed, and Figures 7 (Δ) to <C> are cross-sectional views of the conventional method. 10...Metal tube, 11...Small diameter tube part, 12...
Non-collapsed portion, 13...Dice, 14...Punch.

Claims (1)

[Claims] A small diameter tube part for sealing is formed at the end of the metal tube into which the working fluid is injected after exhausting the non-condensable gas, and when sealing the metal tube by sealing the small diameter tube part, A die having a concave arc surface, and a die having a concave arc surface, and a part of the small diameter tube part with a non-collapsed part of a predetermined size left on the distal end side so that the outer surface is arcuate and a quadrangular truncated pyramid-shaped recess is formed inside. 1. A method for sealing a tube end of a heat pipe, comprising crushing the tube end with a punch having a truncated quadrangular pyramid portion, and then melting and joining the non-crushed portion.