JPH11294981A - Machining method of heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the machining method of a heat pipe that does not affect radiation effect even when performing desired shape machining. SOLUTION: In a machining method of a heat pipe 10, the operating liquid of the heat pipe 10 is frozen, and then the deformation machining of a container 12 is made. Also, in the machining method, the deformation machining is made by nearly instantly freezing from the dry out state of the working liquid where the entire heat pipe 10 is heated on average, by nearly instantly freezing from a state where the operating liquid of the heat pipe 10 is partially vaporized, or by freezing after pouring a proper amount of the liquid inside the container 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a heat pipe, and more particularly to a method for performing a deformation process such as a bending process or a flattening process.

[0002]

2. Description of the Related Art Heat pipes are used to cool main components of portable electronic devices such as notebook personal computers. In recent years, there has been a remarkable demand for thinner and lighter electronic devices.
In order to realize this requirement, the heat pipe has been required to perform various bending and flattening processes more than ever before.

[0003] As is well known, the structure of a heat pipe has a container formed of copper, aluminum, or the like, and a wick that is mainly subjected to group processing or a mesh attached to the inner wall of the container. In this method, a working fluid such as water, ammonia, or alcohol is injected about several tens of percent of the volume in the container.

As is well known, the characteristics of the heat pipe are as follows.
It is intended to equalize the temperature by using latent heat and sensible heat when a gas-liquid two-phase state change occurs. When processing this heat pipe, for example, the interior of the heat pipe using copper as the container material and water as the working fluid is depressurized at room temperature of 25 ° C or less, and becomes pressurized when the temperature exceeds 35 ° C. It is common to work under controlled conditions. However, at the time of processing the heat pipe, since the degree of stress applied by the deformation processing is hardly uniformly applied over the entire circumference of the pipe, undesired deformation of the container or the wick is inevitable and required. There were very many restrictions on deformation processing.

For example, FIG. 1 shows a side cross-sectional view of a cylindrical heat pipe 10 before being flattened and deformed. In FIG. 1, (a) shows a groove wick 14a on an inner wall of a container 12, and FIG. b) mesh wick 14 on the inner wall of container 12
(b) and (c) show the heat pipe 10 provided with the mesh annular wick 14c at the axial center portion of the container 12, respectively. In addition, the shape of the heat pipe 10 in actual use is
The container 12 is arbitrarily deformed and brought into contact with a heat generating portion and a heat radiating portion (not shown).

An L-shaped heat pipe 10 shown in FIG.
FIG. 4 (a) is obtained by bending a heat pipe as shown in FIG. 1 into a shape shown in FIG.
It is deformed as shown in the figure.

[0007]

When such a heat pipe 10 is bent at an angle of 90 degrees as shown in FIG.
In the heat pipe shown in FIG. 1 (b), the mesh wick 14b buckles as shown in FIG. 5 so that it does not adhere to the inner wall of the inner R portion of the container 12, and in a severe case, the steam passage is closed, but not completely. Even this causes various causes of heat transfer performance deterioration. Further, although not shown, the case where the heat pipe 10 shown in FIG. 1C is bent is not shown, but the bias of the wick 14c occurs in the bending direction, which causes a deterioration in performance.

Further, when the heat pipe bent in an L shape in the state of FIG. 4A is flattened, the heat pipe is mainly recessed as shown in FIG. 6A regardless of the wick shown in FIG. This causes the cross section shown in FIG. 6 (b) to occur, and the steam passage is blocked. This dent becomes more pronounced as the degree of flatness increases, and a similar dent occurs in an unbent portion.

[0009] That is, the conventional processing method of arranging and inserting wicks or performing thermal expansion cannot sufficiently respond to the deformation processing required for these.

In view of the above problems, an object of the present invention is to provide a method for processing a heat pipe which does not affect the heat radiation effect even when a desired shape processing is performed.

[0011]

In order to solve the above-mentioned problems, the present invention provides a method for processing a heat pipe in which the working fluid in the heat pipe is frozen and then the container is deformed. Further, the deformation processing is performed almost instantaneously from the dry-out state of the working fluid in which the entire heat pipe is uniformly heated, or is performed almost instantly from the partially vaporized state of the working fluid in the heat pipe. To be
Alternatively, a method of processing a heat pipe performed by injecting an appropriate amount of liquid into a container and then freezing the liquid is used.

After temporarily fixing the wick inside the container, the same liquid as the working fluid is poured and frozen to perform deformation processing, and then the above liquid is partially or entirely discharged leaving an appropriate amount as the working liquid. The working fluid injection step may be performed again, or the liquid may be frozen after a slight bending process is performed on a portion of the heat pipe where the deformation process is performed.

In a heat pipe using copper as a container material, the processing start temperature after freezing using water as the liquid may be set at -30 ° C to -90 ° C.

The liquid may be frozen using liquid nitrogen or dry ice.

[0015] Further, a method of processing a heat pipe in which an appropriate amount of liquid is injected into a container to perform deformation processing, and then a heat pipe is formed. In this case, the same liquid as the working liquid is injected into the container. The heat pipe may be subjected to a deforming process and then partially or entirely draining the liquid while leaving an appropriate amount as a working fluid, and then performing a working fluid injection step again.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a general working method of the present invention, after a straight heat pipe is completed, a working fluid is frozen to perform a desired deformation working. In rare cases, a liquid such as water is put in a container before processing the heat pipe and frozen, and after performing part or all of the desired deformation processing in this frozen state, the heat pipe is formed. Impossible bending R
It is possible to perform various and various deformation processes such as a small object, a very small object having a flat thickness, or a combination thereof.

Next, a description will be given based on a specific embodiment.
FIG. 1 shows a first embodiment of the present invention. FIG. 1 is a side sectional view of three types of cylindrical heat pipes before flattening, and FIG. 1 (a) shows a groove wick 14a, and FIG.
Is the mesh wick 14b, and (c) is the annular wick 14c
Are shown respectively. Book first
In the embodiment of FIG. 1, the container 12 does not need to be used in any of the wicks shown in FIGS. 1 (a), 1 (b) and 1 (c).
Is made of copper, and the working fluid uses water.

FIG. 2A shows an external view of the heat pipe 10 after the cylindrical heat pipe 10 of FIG. 1 has been flattened, and FIG. 2B, FIG. Are (a) and (b) in FIG.
(c) is a cross-sectional view of each section after flattening.
When each of the heat pipes 10 of FIG. 1 is processed into a flat shape as shown in FIG. 2 (a), the container 12 is maintained in a horizontal state, the whole is heated to + 100 ° C., and the working fluid is converted into steam. Immediately after permeating the entire container 12, the working fluid freezes almost instantaneously from the dry-out state by immersing it in a container filled with liquid nitrogen (not shown) at a temperature of −150 ° C. or less, and the entire container 12 is roughened. And then expands in volume.

Next, the heat pipe is taken out of the liquid nitrogen container, set in a press jig, and molded. At this time, since the frozen state of the working fluid is coarse, it is generally not necessary to control the temperature. By performing press molding while controlling the temperature in the range of minus 90 ° C., the container 12 does not lose its freezing liquid and cracks, and the shape shown in FIG. 2A is obtained. The cross sections after processing of FIGS. 1 (a), (b) and (c) are shown in FIGS. 2 (b) and (c), respectively.
There is no distortion as shown in (d). This state is then maintained even after natural thawing.

In particular, FIG. 2 (d) showing a cross section of a heat pipe processed into a flat shape from FIG. 1 (c) is a heat pipe 10 using a mesh annular wick 14c, and a sufficient steam passage is secured. The working fluid is not only in the axial direction of the heat pipe,
Although it can move freely in the width direction, it shows excellent characteristics as a super-flat heat pipe, but mass production by the conventional method was difficult because there was almost no space for the annular wick 14c. . However, according to the heat pipe processing method of the present invention, since the annular wick is prevented from being crushed by the inner wall of the container, the wick can be extended over the entire length in the axial direction.

Further, the working fluid in the heat pipe may be frozen almost instantaneously from a partially vaporized state. This allows
Since the freezing of the steam portion becomes coarse and the water portion is in a frozen state with a high density, the processing accuracy can be increased by freezing the portion where the deformation processing accuracy is required particularly in the water state.

Next, a second embodiment of the present invention is shown in FIG.
FIG. 3 shows a flat heat pipe processed into a multi-stepped shape (a), an L-bending twist shape (b), and a U-shaped shape (c), which are almost impossible with the conventional method. But,
In the heat pipe processing method of the present invention, the heat pipe can be easily formed by the processing method described in the first embodiment or its application. The three shapes shown in FIGS. 3A to 3C are:
Each of them is processed into a flat shape as shown in FIG. 2 above, and then the working fluid is frozen again and pressed to each of the required shapes in the same manner as described above, whereby a highly accurate shape can be obtained. If accuracy is not required,
3 can be performed at once from the unprocessed stage, and this molding method is not much different from processing a normal bar or plate except that the temperature of the object is low.

FIG. 4B shows a third embodiment of the present invention, and FIG. 4C shows a sectional view in the axial direction. Fig. 4 (b)
As shown in (c), the heat pipe 10 is bent in an L shape, and the central axis of the container 12 is formed with a concave portion 16,
A wick 14 is formed on the inner wall of the container 12. The heat pipe processing method according to the third embodiment is the same as the processing method according to the above-described first or second embodiment, and a description thereof is omitted. However, according to the processing method, a cross-sectional view of FIG. The heat pipe 10 having a special shape in which only the central portion shown in FIG. The concave portion 16 has various functions such as a function as a second wick added to the wick 14 of the inner wall of the container, an improvement in strength against external pressure, and an increase in pressure limit of the heat pipe due to a loop of the steam passage. It has the characteristics of

Next, a fourth embodiment of the present invention will be described. In the method of freezing the working fluid described in the first to third embodiments, the working method of freezing the working fluid which has been heated and vaporized almost instantaneously has been described. At the end of the heat pipe 10, when the hydraulic fluid is collected with its part down, and if the central part is slightly bent, the hydraulic fluid is collected in the part to be deformed. The working fluid is put into a low-temperature tank and frozen in a liquid state without heating the heat pipe 10. Of course, liquid nitrogen or dry ice may be used for this freezing. Further, the steps after the freezing are the same as those described in the first to third embodiments, and the description thereof will be omitted.

Next, a fifth embodiment and a sixth embodiment of the present invention will be described. In the above-described first to fourth embodiments, the deformation processing is performed after the completion of the straight heat pipe 10. However, in order to complete the heat pipe 10 having a complicated and high-precision shape, a heat pipe is required. Some or all of the intended deformation processing of the container 12 in the stage before the pipe 10 is completed is performed.

Specifically, the amount of the working fluid after the completion of the heat pipe 10 is reduced from about 15% of the internal volume of the heat pipe 10.
If the deformed portion of the heat pipe 10 is concentrated on a specific portion because it is about 50%, a highly accurate shape can be obtained in the fourth embodiment in which the hydraulic fluid is collected and frozen in that portion. However, when it is desired to perform a complicated deformation as a whole, the desired deformation may not be obtained even if the working fluid is coarsely frozen. For this reason, the container 14 is filled with an appropriate amount of the same working fluid as the working fluid, and the deformation is performed in the liquid state, whereby it is possible to obtain a predetermined accurate deformation. Of course,
After the working fluid is frozen for easy handling, deformation processing such as press molding is often performed.

As a sixth embodiment, the working hydraulic fluid is discharged from the deformed container 12 by heating or the like by leaving a proper amount of the working fluid or by discharging the proper amount of the working fluid after discharging the entire amount. It is also possible to obtain a heat pipe by obtaining an injection step.

In the above embodiment, when ammonia or the like is used as the working fluid, water is used as the working fluid for handling such as waste liquid treatment of the working fluid. In this case, as a matter of course, the working fluid after the deformation processing of the container is completely removed and a predetermined working fluid is injected.

In each of the above embodiments, the wick
Reference numeral 14 indicates that the groove wick, mesh wick, and annular wick may be interchanged.

[0030]

As described above, according to the present invention, after the straight heat pipe 10 was completed, it was impossible in the past without a jig such as a core required for each product processing. Since the heat pipe 10 can be subjected to complicated deformation processing, not only can the manufacturing process be simplified, but also it is possible to quickly respond to various customer demands as the technology evolves.

Further, even for a complicated and highly accurate shape requirement, a liquid such as water is put into the container 12 before the heat pipe 10 is processed, and a part or all of the desired deformation processing is performed in a liquid state or a frozen state. After the heat pipe 10
By doing so, it is possible to perform various and various deformation processes which were impossible with the conventional method.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a heat pipe according to the present invention and a conventional heat pipe before processing.

FIG. 2 shows a heat pipe after flattening according to the present invention and a conventional one.

FIG. 3 shows a heat pipe after processing according to a second embodiment of the present invention.

FIG. 4 shows a heat pipe after processing according to a third embodiment of the present invention.

FIG. 5 is a top sectional view of a bent portion of a conventional heat pipe.

FIG. 6 shows a cross-sectional view of FIG.

[Explanation of symbols]

 In the drawings, the same reference numerals indicate the same or corresponding parts. Reference Signs List 10 heat pipe 12 container 14 wick 14a groove wick 14b mesh wick 14c annular wick 16 concave portion

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[Procedure amendment]

[Submission date] May 7, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claim 2

[Correction method] Change

[Correction contents]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] Claim 3

[Correction method] Change

[Correction contents]

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] Claim 4

[Correction method] Change

[Correction contents]

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] Claim 10

[Correction method] Change

[Correction contents]

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] Claim 11

[Correction method] Change

[Correction contents]

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

[0011]

According to the present invention, a heat pipe is formed by bending or flattening a heat pipe.
Container for performing at least one deformation process such as construction
As a means for reducing the distortion of the heat pipe and the wick, a method of processing a heat pipe in which the working fluid of the heat pipe is frozen and then deformed. Further, the deformation was almost instantly performed after frozen, or almost instantly frozen working fluid of the heat pipe from a state in which the partially vaporized from a dry out condition of the hydraulic fluid that uniformly heats the entire heat pipe After that , or after injecting an appropriate amount of liquid into the container , freeze it,
A method of processing a heat pipe in which at least one deformation processing out of flattening processing is performed.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

[0015] Further, a method of processing a heat pipe, in which an appropriate amount of liquid is injected into a container, and at least one of bending and flattening processes is performed, and then the heat pipe is formed, In this case, the same liquid as the working fluid is poured into the container and bent or flattened.
Further, a method of processing a heat pipe in which at least one deformation processing is performed, and after that, a part or all of the liquid is discharged while leaving an appropriate amount as a working liquid, and then a working liquid injection step is performed again.

Claims (11)

[Claims] 1. A method of processing a heat pipe, comprising deforming a container after freezing a working fluid of the heat pipe. 2. The method of processing a heat pipe according to claim 1, wherein the entire operation of the heat pipe is substantially instantaneously frozen from a dry-out state of the working fluid in which the entire heat pipe is uniformly heated. 3. The method according to claim 1, wherein the working fluid in the heat pipe is frozen almost instantaneously from a partially vaporized state. 4. A method of processing a heat pipe in which a proper amount of liquid is poured into the inside of a container, frozen, deformed, and then turned into a heat pipe. 5. A wick is temporarily fixed inside the container, and then the same liquid as the working fluid is poured into the container and frozen to perform deformation processing. Then, a part of the liquid is discharged or the entire amount is left except for an appropriate amount as the working fluid. The method for processing a heat pipe according to claim 4, further comprising a step of injecting a working fluid after discharging. 6. The heat pipe processing method according to claim 1, wherein the liquid pipe is frozen after slightly bending the portion of the heat pipe where the deformation processing is performed. . 7. A heat pipe using copper as a container material, wherein the liquid is water and the processing start temperature after freezing is minus.
7. The method according to claim 1, wherein the temperature is set from 30 ° C. to −90 ° C.
The method for processing the heat pipe according to the above. 8. The method according to claim 1, wherein the liquid is frozen by using liquid nitrogen. 9. The method according to claim 1, wherein the freezing of the liquid is performed by using dry ice. 10. A method of processing a heat pipe, wherein a proper amount of a liquid is injected into a container and deformed to form a heat pipe. 11. The same liquid as the working fluid is injected into the interior of the container to perform deformation processing, and then the working fluid is injected again after partially or entirely discharging the liquid except for an appropriate amount of the working liquid. The method for processing a heat pipe according to claim 10.