JP3716662B2 - Manufacturing method of flat heat pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat pipe used by being incorporated in various electronic devices, heat-related devices, and the like, a manufacturing method thereof, and a heat pipe type cooling device using the heat pipe.
[0002]
[Prior art]
Conventionally, heat pipes in which a condensable fluid is sealed as a working fluid in a metal tube such as a copper tube have a thermal conductivity that is several to several hundred times better than that of a single metal such as copper or aluminum. Therefore, it is widely used as a cooling element in various electronic devices and heat-related devices.
[0003]
The shape of the heat pipe is generally a circular tube in cross section, but when incorporated in a small portable electronic device such as a laptop computer, the shape of the heat pipe is flat to reduce the size and weight. A pipe-shaped heat pipe is often used.
[0004]
By the way, such a heat pipe having a flat cross section is generally obtained by using a metal pipe having a circular cross section and flattening it so as to crush it in the radial direction as it is. As shown in FIG. 5, when the metal tube 1 is simply crushed in the radial direction, the center portion of the crushed surface is recessed inside the metal tube 1 to generate dents R and R, and smooth flattening is performed. It is difficult to realize, and there is a disadvantage that a desired passage cross-sectional area cannot be obtained.
[0005]
Therefore, for example, as shown in Japanese Patent Application Laid-Open No. 9-49893, the recesses R and R of the crushed surface are obtained by performing the flattening after annealing the metal tube 1 before the flattening to improve the workability. Or a flat processing with an appropriate internal pressure applied by inserting a spring coil 7 inside the metal tube 1 as shown in FIG. 6 (Japanese Patent Laid-Open No. 63-267891), etc. Indentation R, R-preventing flattening method has been proposed.
[0006]
[Problems to be solved by the invention]
However, the former method is effective when the flatness is relatively small, but when the flatness is large, that is, the thickness after flattening is smaller than the diameter of the metal tube having a circular cross section. If it is quite thin, for example, if a round copper tube having a diameter of 5 mm and a wall thickness of 0.2 mm is flattened to a thickness of 1 mm, the depression generated on the crushed surface even if the annealing treatment as described above is performed. It was difficult to prevent R.
[0007]
On the other hand, in the latter method, even if the flatness degree is large, the depression R does not occur on the crushed surface, but the wire diameter of the spring coil 7 is reduced in order to exert an appropriate elastic force on the spring coil 7. Since it is necessary to hold to some extent, there is a drawback that the cross-sectional area of the flat heat pipe is greatly reduced. For this reason, it is conceivable to reduce the wire diameter of the spring coil 7 using a dissimilar metal material having a large elastic force. In this case, the dissimilar metal comes into contact with the galvanic effect in the flat heat pipe, and corrosion occurs. There is a risk of ending up.
[0008]
Therefore, the present invention has been devised in order to effectively solve such a problem, and the purpose thereof is that even if the degree of flattening is large, no depression is generated on the crushed surface, and a sufficient passage cross-sectional area is obtained. can be secured is to provide a novel process for the preparation of the novel flat Hitopai flop.
[0009]
[Means for Solving the Problems]
The present invention in order to solve the above problems, the inside surface of the metal tube of copper in which the cross-section circular, large diameter copper metal wires than the inner diameter of the post will and flat machined from the same material as the metal tube, the and arranged to be positioned at a substantially central portion of the metal tube after flattening processing as well as arranged over the length, after fixing the metal wire to the metal pipe surface and facilities to heat treatment in this state, wherein the metal tube so as to sandwich the metal wires vertically squashed vertically is obtained so as to flat processing.
[0010]
And, in the flat heat pipe obtained in this way, even when the flatness degree is large, the metal wire accommodated in the metal tube is formed of dents generated on both squashed surfaces from the flattening initial stage to the middle stage. In addition to suppressing the growth, the depression is pressed from the inside of the metal tube and acts to eliminate the depression at the end of flattening.
[0011]
As a result, a smooth crushing surface can be obtained without generating depression on the crushing surface of the metal tube, and thus a small and light flat heat pipe that ensures a sufficient passage cross-sectional area can be obtained with certainty.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, a preferred embodiment for carrying out the present invention will be described with reference to the accompanying drawings.
[0013]
FIG. 1 shows an embodiment of a method for producing a flat heat pipe according to the present invention. In the figure, 1 is a metal tube having a circular cross section such as a copper tube, and 2 is the length of the metal tube 1 in its length. The metal wires 3 and 4 arranged along the direction are upper and lower rolls of a roll mill for crushing the metal tube 1 up and down and flattening.
[0014]
First, as shown in FIG. 1 (a), the manufacturing method of the present invention includes a copper wire having a diameter of 0.8 mm in a metal tube 1 made of a round copper tube having a diameter of 5 mm and a thickness of 0.2 mm. The metal wire 2 is inserted and heat treated under the conditions of a heating temperature of 700 ° C. and a heating time of 2 hours to fix the metal wire 2 to the inner surface of the metal tube 1.
[0015]
Next, as shown in the figure, the metal tube 1 to which the metal wire 2 is fixed is positioned between the upper roll 3 and the lower roll 4 positioned above and below, and the outer surface of the portion to which the metal wire 2 is fixed is After the metal tube 1 is rotated and adjusted so as to come into contact with the lower roll 4 side, the upper roll 3 and the lower roll 4 are brought close to each other and flattened so as to crush the metal tube 1 up and down.
[0016]
Then, from the beginning to the middle of the flat processing, as shown in FIG. 1 (b), the upper and lower crushing surfaces are deformed into the insides of the metal tube 1 as dents R and R, respectively. When the upper roll 3 and the lower roll 4 are further brought closer to each other from this state, the top part (lowermost part) of the upper depression R comes into contact with the metal wire 2 and the growth of the further depression R is suppressed. Become.
[0017]
Further, when the upper roll 3 and the lower roll 4 are brought close to 1 mm from this state, the top of the recess R disappears by being pressed against the metal wire 2 as shown in FIG. The metal tube 1 is flattened so as to be smoothed and uniform in thickness. In this flattening, even if the position of the top of the recess R and the metal wire 2 is slightly shifted, the metal wire 2 is fixed in the metal tube 1, so this is the top of the recess R. It will act to surely correct the recess R smoothly without being pushed to the left and right. The total distance between the thickness (0.2 mm × 2) of the metal tube 1 and the diameter (0.8 mm) of the metal wire 2 is 1.2 mm, and the distance between the upper roll 3 and the lower roll 4 (1 mm). Although the contact surface of the metal wire 2 is somewhat crushed or flattened into the inner wall of the metal tube 1 during flattening, it is flattened to the distance (1 mm) between the upper roll 3 and the lower roll 4. It will be.
[0018]
As a result, it is not necessary to perform the long-time annealing process that was required before flattening as before, and the manufacturing time required for flattening can be shortened. The flattening can be easily and reliably performed on the metal tube 1 without causing the above. In addition, such troubles as the use of the coil spring 7, such as the labor of manufacturing the coil spring 7, the loss of the passage cross-sectional area, the internal corrosion, etc., can be avoided.
[0019]
Then, the flat heat pipe having a thickness of 1 mm obtained in this way is used as a cooling element, for example, nickel plating or the like, and is attached in close contact with a heat sink made of aluminum having a thickness of 0.5 mm. It becomes possible to obtain a heat pipe type cooling device with a thickness of 1.5 mm, and if this is incorporated into a portable small electronic device such as a notebook computer, the portable small electronic device can be further reduced in size and weight. Can contribute.
[0020]
Next, FIGS. 2 to 4 show another embodiment of the present invention.
[0021]
First, in FIG. 2, a metal mesh 5 such as a copper mesh is interposed around the metal wire 2 in the metal tube 1 described above (FIG. 2A). 1 and flat processed. As a result, a flat heat pipe in which the metal mesh 5 is securely fixed around the metal wire 2 as shown in FIG. 2B can be easily manufactured.
[0022]
Next, FIG. 3 shows a case in which a plurality of extra fine wires 6 are accommodated in the metal mesh 5 shown in FIG. 2 and a wick material is combined (FIG. 3A). Thus, it is possible to easily manufacture a flat heat pipe in which the fine wires 6 are uniformly arranged around the metal wire 2 as shown in FIG. 3 (b). it can.
[0023]
Further, FIG. 4 shows that at least two or more (three in the present embodiment) metal wires 2 are fixed in the metal tube 1 at regular intervals (FIG. 4A). The flattening process is performed similarly to the above. That is, when the flattening degree is higher, for example, when the metal tube 1 having the same thickness as the metal tube 1 of the above-described embodiment and having a diameter of only 10 mm is flattened to 1 mm, 1 The metal wire 2 alone cannot support the recess R, and it becomes difficult to flatten the flattened surface. However, as shown in FIG. On the other hand, if two or more metal wires 2 are installed at a predetermined interval, the flattened surface can be surely flattened even when the flattening degree is higher. Furthermore, as shown in the figure, the flattening may be performed after the metal mesh 5 and the ultrafine wire 6 described above are accommodated in the metal tube 1 during the flattening.
[0024]
The same effect can be obtained by using an aluminum metal tube and a metal wire in place of the copper metal tube 1 and the copper metal wire 2 used in each of the above-described embodiments. Needless to say, the optimum conditions may be adopted each time depending on the metal and size used. Further, the flattening process is not necessarily limited to the roll mill, and may be performed by a press machine or the like.
[0025]
【The invention's effect】
In short, according to the present invention, even when the flattening degree is large, it is possible to reliably flatten the crushed surface of the metal tube. It is possible to exhibit excellent effects such as being able to easily and reliably obtain a high-quality flat heat pipe that is free from the occurrence of internal corrosion and internal corrosion.
[Brief description of the drawings]
FIG. 1 is a process diagram showing an embodiment of a flat heat pipe and a manufacturing method thereof according to the present invention.
FIG. 2 is a cross-sectional view showing another embodiment of the present invention.
FIG. 3 is a cross-sectional view showing another embodiment of the present invention.
FIG. 4 is a cross-sectional view showing another embodiment of the present invention.
FIG. 5 is a cross-sectional view showing a state in which a metal tube having a circular cross section is flattened as it is.
FIG. 6 is a cross-sectional view showing a state in which a coil spring is inserted into a metal tube having a circular cross section and then flattened.
[Explanation of symbols]
1 Metal tube 2 Metal wires 3 and 4 Roll 5 Metal mesh 6 Fine wire 7 Spring coil R Dimple

Claims (1)

The inner surface of the metal tube of copper in which the circular cross section, after flattening processing with a large diameter copper metal wires than the inner diameter of the post will and flat machined from the same material as the metal tube, arranged over its length substantially arranged so as to be positioned at the center portion, after fixing the metal wire to the metal pipe surface and facilities to heat treatment in this state, the metal so as to sandwich the metal wires above and below of the metal tube A method for producing a flat heat pipe, wherein the pipe is crushed up and down and flattened.

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