JPH037889A - How to manufacture heat pipes - Google Patents

Abstract

PURPOSE:To efficiently manufacture heat pipes in mass by first filling the operating liquid in a coiled elongate metallic pipe one end of which is sealed, and then cutting the pipe at the cutting section after forming the sealed sections on both sides of the cutting section by applying heat higher than the critical temperature of the operating liquid. CONSTITUTION:One end 2 of an elongate metallic pipe 1A is sealed, and the operating liquid is filled therein. Part of the liquid is caused to evaporate and discharged from the filler neck 3 to purge the incondensable gas remaining therein. After the end of the filling opening 3a is sealed, the pipe is wound in a coiled heat pipe 5. The coil 5 is heated in a heating device 6 to maintain the operating liquid in its super critical state. After the operating liquid evaporated and uniformly diffused in the pipe, the pipe is fed by means of pinch rolls 7, 8 and sealed by means of a pinch sealing device 9 at every desired length of heat pipe. The sealing is carried out by applying calking and TIG welding, for instance, on both sides of the cutting section 12 of the pinch sealing section 11.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a novel method for manufacturing heat pipes that can mass-produce heat pipes with excellent performance extremely efficiently and stably, and in particular, relates to a method for manufacturing heat pipes with a small diameter. The present invention relates to a very convenient manufacturing method for manufacturing heat pipes.

[Prior art 1] In recent years, as shown in FIG. 6, a working fluid 4 is sealed in one end of a sealed metal tube 1 of a predetermined length, and the working fluid is made to absorb heat and turn into steam 4a on the heat collecting part P side. The heat dissipation part Q on the a end side of the tube
The steam is condensed into liquid 4b in the heat dissipation section, and the liquid 4b is returned to the heat collecting section P side, and the heat dissipation during the condensation is utilized to transfer the vapor to the heat dissipation section Q. A heat pipe 20 formed by m is used in various fields to heat the surrounding area.

Specifically, in addition to cooling high-power silicon rectifiers, geothermal energy can be used to melt snow around steel towers, or attached to branch lines of utility poles in areas with heavy snowfall to melt snow, preventing breakage of branch lines due to the settling force of snow. Its application is also attracting attention in new fields such as preventing slope collapse of electric wires.

However, the conventional method of manufacturing such a heat pipe is to clean the inner surface of a metal tube 1 made of copper or stainless steel, etc., and seal one end by welding or the like, as shown in Figure 1. A hydraulic fluid injection tube 3 section is formed with an injection port 3a for hydraulic fluid injection at the other end (if the diameter is particularly small, an appropriate separate member may be provided), and when the boiling point is below room temperature, the injection tube After evacuating the inside through step 3, the working fluid is injected. In addition, if the boiling point of the working fluid is above room temperature, the working fluid 4 is directly injected in the atmosphere, the whole is heated above the boiling point of the working fluid 4, and steam is ejected from the injection pipe 3, so that steam remains inside the pipe. A method is used in which the distal end of the injection tube 3 is sealed after the non-condensable gas is mixed and discharged together with the vapor of the working fluid.

[Problem to be solved by the invention] As is clear from the above explanation, manufacturing a heat pipe involves injecting a working fluid into each individual product and sealing the entire pipe, which is extremely difficult from an industrial perspective. It is uneconomical.

In addition, in order to ensure sufficient performance of the heat pipe, it is necessary to sufficiently remove non-condensing scum.
Eliminating this noncondensable gas takes a lot of effort, and
If the heat pipe has a small diameter and is long, it is often very difficult to completely remove the residual non-condensable scum.

Therefore, as disclosed in Japanese Patent Publication No. 58-40118, for example, a long pipe with a small diameter is filled with hydraulic fluid and then heated to sufficiently evaporate the hydraulic fluid so that the entire inside of the pipe is activated. A method has been proposed in which after the liquid has a uniform vapor pressure, the ends of the pipes are sealed, the pipes are pinched at arbitrary positions, and the heat pipes are loaded into a plurality of heat pipes.

However, according to this method, the working fluid held in the heat pipe is evenly distributed in each heat pipe and it is possible to manufacture a heat pipe having uniform performance. Publication No. 8 only discloses the principle thereof, and does not disclose any concrete means for industrially mass-producing it with high efficiency and reducing manufacturing costs.

It is an object of the present invention to provide a heat pipe which eliminates the problems associated with the prior art as described above, has high performance with simple means, and is free from industrial manufacturing restrictions.
In particular, it is an object of the present invention to provide a novel method for manufacturing heat pipes that can efficiently mass-produce long heat pipes with a small diameter and make it possible to significantly reduce costs.

[Means for Solving the Problems] The present invention has one end sealed and a working fluid injected from the other end of a long metal tube having a length equivalent to a plurality of heat pipes to discharge residual noncondensable gas. At the same time, the whole is made into a coil shape and stored in a heating device, and the coil is heated to a temperature higher than the critical temperature of the working fluid in the injected long metal tube,
The working fluid within the entire length of the long metal tube is maintained in a supercritical state, and under this condition, airtight sealable airtight parts are formed on both sides of the cutting section for cutting the long tube into the required length. Then, the tubes are sequentially cut off at the cutting portions, leaving the hermetic seals on both sides.

[Function] If the entire long metal tube is formed into a coil shape, it can be easily accommodated in a commonly used device such as a normal annealing furnace, and if heated using such a commonly used heating device, it can be heated for a long time. Since it is possible to uniformly heat the entire length of the metal tube, and the heating temperature can also be controlled within an extremely fine range, it is possible to reach the temperature necessary to discharge the non-condensable gas contained in the working fluid. The long metal tube itself can be easily heated, thereby making it possible to completely discharge residual noncondensable gas and maintain the working fluid in a supercritical state.

By sealing the heat pipe to the required length and cutting it using conventional means, it becomes possible to mass-produce a heat pipe with a homogenized working fluid.

[Example] The present invention will be described below with reference to Examples.

Figure 2 shows a long metal tube IA (made of conventionally used copper or copper alloy, stainless steel, or aluminum or aluminum alloy) that is long enough to cut into multiple heat pipes. As shown in Fig. 1, one end portion 2 of the long metal tube IA is sealed by caulking, TIG welding, etc., as shown in Fig. 1. After injecting the working fluid by means of the vacuum method, a part of it is evaporated and discharged from the injection pipe 3 to exhaust the harmful non-condensable gas remaining inside the container, and ensure that the discharge is sufficient. At this stage, the tip of the injection hole is sealed and the whole is sealed into a long metal tube I.
A long coil-shaped heat pipe is formed.

When injecting the working fluid 4 whose boiling point is higher than room temperature, the working fluid 4 is injected and heated in the atmosphere as described above.

After the hydraulic fluid is injected, the coil 5 is housed in the heating device 6 as shown in FIG.

Such a heating device 6 is provided by the applicant, for example.
It is regularly equipped for various purposes such as manufacturing long copper pipes or annealing thick wire or rough drawn wire, and a pinch roll 8, a pinch seal device 9, and a guide are shown in FIG. 3 by slightly modifying this equipment. By attaching an additional device such as the tube 10, it would be possible to easily modify the coil 5 without requiring a large expense.After the coil 5 is housed in the heating device 6 as shown in FIG. 3, the coil 5 is heated. The entire length of the working fluid within the long metal tube IA is maintained in a supercritical state.

The supercritical state here means that all the working fluid is sufficiently vaporized.

If the gas is heated to a supercritical state in this way, it will be in a state where the pressure is uniform and evenly distributed within the long pipe IA due to the properties of the gas.

Once the internal working fluid has been vaporized and uniformly distributed in the long metal tube IA, the third
The heat pipes are sent out using pinch rolls 8 shown in the figure, and hermetically sealed using a pinch sealing device 9 for each required length of the heat pipe.

When taking out the heat pipe cut to a predetermined length from the guide tube 10, caulking or TIG welding may be performed within the guide tube 10. Since there is no pressure difference inside the pipe, welding work is very easy.

FIG. 4 is an explanatory view showing an example of cutting in this way, and shows the above-mentioned caulking and the like on both sides of the cut portion 12 of the pinch seal portion 11 to be cut of the long metal tube IA. Using IG welding, or if the metal tube has a small diameter, insert the hermetically sealed portion of the long metal tube IA into the die groove 14 of the sealing die 15 as shown in FIG. Seal well by crimping.

Note that if you select a working fluid with a boiling point above room temperature, if you take the heat pipe out into the atmosphere, there will be a negative pressure inside and there is a risk of air infiltrating, so make sure it is completely airtight before taking it out from the guide mto. Sealing the condition is a must.

If heat pipes are formed by cutting long metal tubes with uniform distribution of working fluid into the required lengths as described above, all heat pipes will have uniformity, and This makes it possible to industrially mass-produce heat pipes with high performance in an extremely efficient manner.

Regarding the amount and type of hydraulic fluid to be injected in the above, the amount required to operate as a heat pipe is determined, and it is necessary to inject this within the determined range and the type of hydraulic fluid injected. Alternatively, it is practically easy to consider the material and size of the metal tube and select an appropriate temperature to obtain the above-mentioned supercritical state.

This will be explained using a specific example.

Let us consider a case where copper or stainless steel is used as the material of the heat pipe, and Freon R22, which is widely used, is used as the working fluid. The critical temperature of Freon R22 is 96°
C1 critical pressure is 50.2kg/aa+” abs
and its critical density is 164CC/sol (0,
525/J).

Therefore, if the inner diameter and length of the long metal pipe IA are determined, the amount of working fluid to be injected into the inside is also determined, and by injecting this amount into the long heat pipe, the The optimum amount of working fluid is retained within the heat pipe, and a saturated state of liquid and steam always coexists within the heat pipe, allowing the heat pipe to exhibit optimal performance.

In addition, if the inside of the guide tube 10 is evacuated when sealing and cutting the heat pipe at the pinch sealing part (many Ws use vacuum evacuation and annealing in this way), the long metal tube IA can be guided. It is also possible to first cut the tube inside the tube 10 and seal the end thereof by molding or other processing.

If the length of the heat pipe to be cut is determined from the beginning, you can reduce the diameter of the long metal pipe LA at the point where it is to be cut, without having to measure it. It has the advantage that it can be cut and sealed.

[Effects of the Invention] According to the manufacturing method according to the present invention, it is possible to mass-produce heat pipes with uniform performance and excellent performance at a low cost, and it is especially possible to manufacture fine heat pipes that are difficult to manufacture. Extremely excellent effects can be exhibited in the production of heat pipes with long diameters.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view showing the state of manufacturing a heat pipe, FIG. 2 is a sketch showing how a long metal tube according to the present invention is coiled, and FIG. 3 is a process for manufacturing a heat pipe according to the present invention. Fig. 4 is a sketch showing a specific example of cutting a long metal pipe, Fig. 5 is an explanatory drawing showing an example of sealing the pipe end with a die and punch, and Fig. 6
The figure is an explanatory diagram showing the operation of the heat pipe.

Claims (1)

[Claims] (1) One end of a long metal tube corresponding to the length of multiple heat pipes is sealed and a working fluid is injected from the other end to exhaust the remaining non-condensable gas, and the whole is formed into a coil shape. The coil is heated to a temperature higher than the critical temperature of the working fluid in the injected long metal tube, thereby maintaining the working fluid within the entire length of the long metal tube in a supercritical state. Under this condition, a hermetically sealable airtight part is formed on both sides of the cutting part for cutting the long tube to the required length, and the pipe is sequentially separated at the cutting part, leaving the hermetically sealed part on both sides. A method for manufacturing a heat pipe in which a plurality of heat pipes are produced.