JPS5854357B2 - Manufacturing method of heat pipe with inner groove - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a heat pipe with internal grooves that ensures reliable brazing of the pipe ends.

In general, a heat pipe is a metal tube whose interior is depressurized and a working fluid with a relatively low boiling point, such as water or alcohol, is sealed, one end of the metal tube serves as a heat receiving section, and the other end serves as a heat dissipating section.
Due to the rapid transfer of latent heat due to evaporation and condensation of the working fluid,
It is a high-performance heat transfer device with an equivalent thermal conductivity more than 1,000 times that of copper.

Conventionally, as a means for returning this working fluid to the heat-receiving part, a porous material such as gold steel, glass fiber, or sintered body is provided on the inner surface of a metal tube to form a wick, and the working fluid is returned by the capillary action of this wick. ing.

However, it is difficult to provide these wicks in close contact with the inner surface of a long metal tube, so as shown in FIG. 2... has been developed to utilize its capillary action.

In manufacturing the heat pipe 3 provided with the grooves 2 in this way, a ring-shaped brazing material 4 is inserted into the pipe end 1a, a cap 5 is attached, and this part is heated and brazed to seal the inside. .

However, during this brazing process, the melted brazing material 4 is sucked up by the capillary action of the grooves 2.
The solder metal 475 was not sufficiently applied to the joint portion, and the solder metal had the disadvantage that it was easily defective.

In the present invention, as a result of conducting various studies in view of these drawbacks, we have discovered a method of manufacturing a heat pipe that ensures a sufficiently airtight structure by reliably brazing the ends of the tube.

That is, the present invention involves cutting and removing a predetermined length of grooves from both ends of a metal tube in which a large number of grooves are formed along the longitudinal direction of the inner surface, and then inserting a ring-shaped brazing material into the removed portion. At the same time, a cap having an annular step formed along the outer periphery is provided so that the step fits into the brazing material,
This method of manufacturing a heat pipe with internal grooves is characterized in that after this portion is heated and brazed, the inside of the metal tube is depressurized and a working fluid is sealed.

The present invention will be explained in detail below based on the drawings.

2 to 6 are cross-sectional views sequentially showing the present invention according to the steps. First, as shown in FIG. 2, aluminum, copper,
After forming a large number of grooves 2 along the longitudinal direction on the inner surface of a metal tube 1 made of stainless steel or the like, the grooves 2 are formed over a predetermined length from the tube ends 1a, 1a'.
... to be deleted.

Next, as shown in FIG. 3, ring-shaped brazing fillers 4, 4 are inserted into the removed portions 1b, 1b', and then the steps 6a are inserted along the outer periphery.
Remove the cap 6.6' with the removed portion 1b so that the stepped portion 6a fits into the brazing material 4.

1b'.

In this case, the cap 6' inserted into the removed portion 1b' has an exhaust port 6b formed in its center.

Next, the tube end 1a is heated and the metal tube 1 and the cap 6 are brazed together as shown in FIG.

In this case, since the molten brazing material 4 is provided apart from the groove 2, it will be sucked up by its capillary action, and the molten brazing material 4 may be drawn between the stepped portion 6a and the inner wall portion of the metal tube 1. The brazing material accumulates in the annular groove formed between the pipes, and also flows around in the circumferential direction due to the capillary action of a portion of the corner of this groove, so that the end portion of the pipe can be reliably brazed.

Next, this metal tube 1 is turned over, and the tube end 1a' into which the cap 6' is inserted is heated and brazed in the same manner.

Next, the air in the metal tube 1 is degassed from the exhaust port 6b of the cap 6' and maintained in a reduced pressure state, and then a working fluid 7 such as water or alcohol is injected as shown in FIG. 8 into the exhaust port 6b.

This blind rivet 8 has a cylindrical body 8b with a threaded groove 8a on its inner surface, and a collar plate 8c provided at the open end of the cylindrical body 8b. After screwing into the thread groove 8a of the metal tube 1, the tip of the cylindrical body 8b is plastically deformed and caulked by pulling up the pulling rod as shown in FIG. 6, and the inside of the metal tube 1 is sealed and heated. This is called pipe 3.

FIG. 7 shows another embodiment of the present invention, in which the outer diameter of the cap 6 is made equal to the outer diameter of the metal tube 1, and the stepped portion 6a is inserted into the removed portion 1b of the groove 2. It is also possible to do so.

In the above embodiment, a blind rivet 8 is used as a method of sealing the metal tube 1, but the present invention is not limited to this. It is also possible to seal off the exhaust pipe after injecting 7.

As explained above, according to the method for manufacturing a heat pipe according to the present invention, even in a metal tube provided with grooves on the inner surface for returning the working fluid by capillary action, the melted brazing material is formed in the grooves when the pipe ends are brazed. The melted brazing material does not get sucked up into the groove, but instead flows around in the circumferential direction at the corner of the annular groove formed between the stepped part of the cap and the inner surface of the metal tube, ensuring a tight seal at the end of the tube. It is of extremely great industrial value as it can be used in many different applications.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the tube end portion of a heat pipe showing a state in which the tube end is sealed by a conventional method, and FIGS. 2 to 6 are cross-sectional views sequentially showing the steps of manufacturing a heat pipe by the method of the present invention. FIG. 7 is a sectional view showing another embodiment of the present invention. 1...Metal tube, 1a, 1a'...Tube end, lb. 1b'...Removed portion, 2...Groove, 3
... Heat pipe, 4 ... Brazing material, 5
, 6...Cap, 6a...Step part, 6
b...Exhaust port, 7...Hydraulic fluid, 8...
····Blind rivet.

Claims (1)

[Claims] 1 After cutting and removing the grooves over a predetermined length from both ends of a metal tube in which a large number of grooves have been formed along the longitudinal direction of the inner surface, a ring-shaped brazing material is inserted into the removed portion, and the outer surface is A cap with an annular step formed along the periphery is provided so that the step fits into the brazing material, and after this portion is heated and brazed, the inside of the metal tube is depressurized to drain the working fluid. A method for manufacturing a heat pipe with an internal groove, characterized by enclosing the heat pipe.