JPH038847B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing a raw tube for use as an exterior body of a heat pipe, and particularly for a group wick type heat pipe with a thin groove in the wick. The present invention relates to a method for manufacturing a raw pipe.

<Prior art> As is well known, in a heat pipe, when heat is applied to one end, the working fluid sealed inside evaporates, and the vapor flows to the other end where it radiates and condenses heat, thereby transporting heat. The condensed and liquefied working fluid is then refluxed to the one end side by the capillary pressure provided on the inner wall of the tube.

Conventionally, metal mesh, porous sintered metal, or narrow grooves (groups) are known as devices that form a return flow path for liquid-phase working fluid and generate sufficient capillary pressure. Although sintered metal can obtain high capillary pressure, it is separate from the metal tube that forms the exterior body of the heat pipe.
Manufacturing the heat pipe as a whole takes time and effort.

On the other hand, although the capillary pressure of the group heat pipe is slightly lower, it is formed directly on the inner surface of the metal tube serving as the exterior body, so it is easy to manufacture the heat pipe as a whole. Further, if a group wick is employed, the thermal resistance between the outer surface of the heat pipe and the working fluid inside is reduced, so that the heat transport ability of the heat pipe as a whole can be improved.

<Problems to be Solved by the Invention> As described above, group wicks have various excellent features, so they are widely used as much as metal nets and porous sintered metals. Methods for forming groups on the inner surface of a metal tube that act as It has been known. However, the former method has the disadvantage that it is very difficult to form a large number of narrow grooves to generate sufficiently high capillary pressure, and the process takes time; It is difficult to set the wall thickness of the tube to be obtained, so if a thin-walled tube is used as the material to reduce the wall thickness of the final tube, there is a risk that the tube will break during extrusion. In addition, each of the above-mentioned methods requires forming grooves on the inner surface of the tube by machining such as cutting, which poses difficulties in manufacturing workability.

On the other hand, the metal tube that forms the exterior body of the heat pipe is
In order to reduce the thermal resistance between the heat source on the outer surface and the internal working fluid, it is preferable that the wall thickness be as thin as possible, but in the past, sufficient strength was required when machining grooves. A commercially available standard product was also used as the exterior body of the heat pipe, and as a result, it was not possible to sufficiently lower the thermal resistance of the heat pipe as a whole.

Furthermore, if there are impurities other than the working fluid inside the heat pipe, the evaporation and flow of the working fluid will be hindered, making it impossible to obtain the desired heat transport ability. However, in the above conventional method for forming group wicks,
When forming grooves on the inner surface of a metal tube, a large amount of lubricant and coolant such as cutting oil must be used, which makes cleaning work prior to filling in the working fluid more difficult, especially over a long period of time. In the case of short tubes, there are problems such as cleaning work being extremely difficult.

This invention has been made in view of the above circumstances, and is intended for use in heat pipes that have grooves that function as wicks formed on the inner surface, that are easy to clean prior to enclosing working fluid, and that have low thermal resistance. The object of the present invention is to provide a manufacturing method that allows raw pipes to be obtained easily and continuously.

<Means for Solving the Problems> That is, in the manufacturing method of the present invention, while running a metal tape, a large number of grooves with a rectangular cross section are formed along the longitudinal direction on one surface of the tape, and then the grooves are The surface on which the groove was formed is cleaned to remove impurities, and then the width of the opening of the groove is increased from the bottom by gradually curving both side edges of the metal tape so that the surface on which the groove is formed is on the inside. This is characterized in that a tubular body that becomes the base tube of a heat pipe is obtained by narrowing the tube and fixing the abutted side edges to each other.

Here, the metal tape used in this invention is preferably a metal with good thermal conductivity such as copper, which has been softened by annealing or the like in advance.
Further, it is preferable that the thickness thereof be as thin as possible within a range that allows formation of grooves in a subsequent process. The grooves can also be formed by cutting one side of the metal tape with a cutting tool such as a cutting tool arranged in parallel along the width direction of the metal tape.
A plurality of protrusions along the circumferential direction are formed on the outer peripheral surface of the roll at regular intervals in the axial direction, the roll is pressed against one surface of the metal tape, and the protrusions are applied to one side of the metal tape. The groove may be formed by plastically deforming the surface of the groove. Furthermore, the cleaning step is carried out to remove impurities that inhibit the evaporation and flow of the working fluid when the tubular body obtained by forming the metal tape into a tubular body is used as a heat pipe. The cleaning step includes washing away impurities with an organic solvent, wiping with a cloth, sponge, etc., and heating and evaporating the solvent, moisture, etc.

Furthermore, when a metal tape is rolled into a circle, it is preferable to secure the butt-side edges of the metal tape by welding in order to ensure airtightness, and the typical welding method is TIG welding. and high frequency electric resistance welding.

<Examples> Examples of the present invention will be described below with reference to the drawings.

First, an example of an apparatus for carrying out the method of the present invention will be described with reference to FIG. 1. A metal tape 1 is wound onto a reel 2 and set on a stand 3, and the metal tape 1 is sequentially fed out from there. Next, a groove machining device 4 is arranged in front of it. This groove machining device 4 includes, for example, a plurality of cutting tools 4a arranged in parallel along the width direction on the upper surface side of the metal tape 1, as shown in FIG. It consists of a tool 4a and a supporting roll 4b arranged opposite to each other, and is configured to cut a large number of grooves G on the upper surface in the longitudinal direction of the metal tape 1 which is passed by the plurality of cutting tools 4a. A device is used. Another groove processing device 4 is a groove processing roll 4 having a large number of protrusions 4c in the circumferential direction on the outer peripheral surface as shown in FIG.
d and the support roll 4b, with the metal tape 1 sandwiched between them, and the protrusion 4c of the groove processing roll.
It is possible to use a metal tape configured to plastically form grooves G on the upper surface of the metal tape 1.
A cleaning device 5 is arranged in front of this groove processing device 4. This cleaning device 5 mainly cleans the surface of the metal tape 1 on which the grooves G are formed to remove impurities. and a wiping roll 5b for wiping off impurities;
The heating dryer 5c sprays hot air onto the upper surface of the metal tape 1 to evaporate impurities that can be removed by evaporation. Further, in front of the cleaning device 5, a pipe former 6 mainly composed of a plurality of pairs of forming rolls consisting of a drum-shaped roll 6a and a drum-shaped roll 6b is disposed, and the surface on which the groove G is formed is on the inside. metal tape 1
The metal tape 1 is formed into a tubular shape by gradually curving both left and right sides of the metal tape 1. In front of this pipe former 6, a welding device 7 consisting of a TIG welder, a high frequency electric resistance welder, etc. is arranged to join the side edges of the metal tapes 1 that abut each other, and the welding device 7 A take-up machine 8 mainly composed of pinch rolls is provided in front of the machine.

Next, to explain the operation of the device configured as described above, that is, an example of the manufacturing method of the present invention, when the take-off machine 8 is driven, the metal tape 1 is paid out from the coil 2 and enters the groove processing device 4, and the upper surface A groove G is formed in the groove. Here, when using the groove machining device 4 configured to cut with a cutting tool 4a as shown in FIG. 2, appropriate cutting oil is applied to the cutting part for cooling and lubrication during cutting. In addition, when the groove processing device 4 is configured to perform plastic processing as shown in FIG. 3, the metal tape 1 is heated to a predetermined temperature in advance. The metal tape 1 with the grooves G formed in this way then enters the cleaning device 5, where impurities such as cutting oil, chips, and oil that has adhered to the metal tape 1 in advance are removed. When heating and drying the metal tape 1 in the final stage of this cleaning device 5, if the temperature is set slightly higher than the operating temperature when the tubular body P is used as a heat pipe, which will be described later, when the heat pipe is operated. Impurities that may evaporate can be reliably removed, and there is no risk of malfunction of the heat pipe or reduction in heat transport ability. The metal tape 1 that has been cleaned as described above is gradually curved at both side edges by the pipe former 6 so that the surface on which the groove G is formed is on the inside, and the abutted side edges are used for the next stage. The metal tapes 1 are joined to each other by a welding device 7, so that the metal tapes 1 are finally formed into a tubular body P. In addition, when the metal tape 1 is curved into a tubular shape as described above, since the groove G is formed in the metal tape 1 in advance, the metal tape 1 can be curved very easily. The groove G has a rectangular or rectangular cross section as shown in FIG. 4A, and after the metal tape 1 is bent into a tubular shape, the groove G becomes trapezoidal and has an opening as shown in FIG. 4B. As a result, when the tubular body P is used as a heat pipe, the groove G has a small flow resistance to the liquid phase working fluid.
It also functions as a wick that generates large capillary pressure. Note that, as mentioned above, when the metal tape 1 is bent, the width of the opening of the groove G becomes narrower, so when forming the groove G, the width of the opening should be widened to some extent. Of course, the opening of the groove G should not be closed when the metal tape 1 is bent.

The tubular body P obtained as described above, that is, the raw tube for the heat pipe, is pulled out by the take-off machine 8, cut into a required length in a subsequent process, and then both ends thereof are sealed with end plates. Thereafter, the non-condensable gas inside is evacuated, and a condensable working fluid such as water or ammonia is filled in to form a heat pipe. In addition, when a non-condensable gas is exhausted and a condensable working fluid is enclosed, the tubular body P has sufficient impurities removed from the inner surface during its manufacturing process, so it is not necessary to carry out any particular cleaning work, so that so-called flushing can be carried out. It is only necessary to carry out the steps several times, and therefore, overall, the raw tube obtained by the method of the present invention facilitates the manufacturing work of the heat pipe.

FIG. 5 is a partially cutaway perspective view showing an example of the heat pipe of the present invention obtained by the above method, and the inner peripheral surface of the pipe P has a large number of grooves (openings ) G is provided.

A heat pipe of an example obtained by the present invention and a pipe were prepared in advance for comparison.
The results of characteristic tests conducted on the heat pipe of the comparative example in which grooves were formed on the inner surface by an etching method or a rolling method are as follows.

The tape according to the embodiment of the present invention is made of copper (aluminum, stainless steel, etc.) with a width of 180 mm and a thickness of 2.5 mm.
Prepare a tape, cut and remove both ears, make a tape with a width of 157 mm, and make a pipe with a groove width of 0.5 mm, a width of the non-groove part of 1.0 mm, and a groove depth of 1.0 mm.The inner diameter is 45 mmφ and the outer diameter is 50 mmφ. , a heat pipe with 98 grooves. (Both ends were sealed with the same material.) This groove had a width of 0.5 mm at the bottom and 0.45 mm at the opening. Using this, a heat pipe with dimensions as shown in FIG. 6 was created.

At the same time, the heat pipe of the comparative example, in which grooves were created using the etching method or rolling method mentioned above, has the same inner shape and outer diameter as the example, and the grooves are the same at the bottom and the opening.
The only difference from the example is that the heat pipe is 0.5 mm. Regarding the above heat pipes of the example and comparative example,
The relationship between temperature and heat transport was investigated. This result is the 7th
As shown in the figure, it was recognized that the heat transfer amount of the device according to the present invention was large, and the scattering limit of the heat medium increased.

<Effects of the Invention> As is clear from the above explanation, according to the manufacturing method of the present invention, a raw tube for a heat pipe is obtained using a metal tape as a material, so the wall thickness of the raw tube can be reduced as necessary. This makes it possible to obtain a raw pipe that not only has low thermal resistance but also good thermal conductivity and is lightweight. Furthermore, since the grooves that function as wicks are processed prior to the process of bending the metal tape into a tubular shape, the process is extremely easy.Moreover, the metal tape is cleaned prior to the process of bending the metal tape into a tubular shape. Even if cutting oil is used during groove machining, it can be easily removed and a raw pipe with a clean inner surface can be obtained. Furthermore, since the metal tape is curved into a tubular shape after processing the grooves with a square cross section, the width of the opening of the groove, which functions as a wick, can be made narrower than its bottom, and the said groove can therefore be formed into a liquid phase. The flow resistance to the working fluid is low and high capillary pressure can be generated.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a device for carrying out the method of the present invention, FIG. 2 is a schematic diagram showing an example of the groove machining device, and FIG. 3 is a schematic diagram showing another example of the groove machining device. 4A is a sectional view showing the groove before deformation, FIG. 4B is a sectional view showing the groove after deformation, and FIG. 5 is a partially broken perspective view showing an example of the heat pipe obtained by the present invention. , FIG. 6 is a dimensional diagram of a heat pipe for comparative testing, and FIG. 7 is a graph of comparative test results regarding temperature and heat transport amount. 1... Metal tape, 4... Grooving device, 5...
Cleaning device, 6...pipe former, 7... welding device, G... groove, P... tubular body.

Claims (1)

[Claims] 1. While running a metal tape, a large number of grooves with a rectangular cross section are formed in the longitudinal direction on one surface, and then the surface on which the grooves are formed is cleaned to remove impurities, and then the grooves are removed. By gradually curving both sides of the metal tape so that the surface forming the groove is on the inside, the width of the opening of the groove is made narrower than the width of the bottom, and the abutted side edges are fixed to each other. A method for producing a raw tube for a heat pipe, the method comprising obtaining a tubular body.