JPH0754236B2 - Heat pipe manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for efficiently manufacturing a heat pipe having extremely narrow passages that constitute a wick for transporting liquid, and more specifically, a precise passage. The present invention provides a method for manufacturing a heat pipe in which the transport distance of a liquid is increased by forming the pipe to be long in the axial direction of the tubular body.

[Prior art and its problems]

A heat pipe is one in which a transport passage that uses the surface tension of the liquid and a vapor transport passage are formed in the pipe, and if the liquid transport wick can transport the liquid to a long distance, an efficient heat pipe will be manufactured. It is possible to

As the type of the liquid transport wick, there is a type in which a groove extending in the axial direction of the pipe is formed. In this type of heat pipe, the narrower the groove width of the wick, the more the liquid transport by surface tension. It would be desirable to manufacture wicks with narrow groove widths as this would increase the quantity and the transport distance.

Heat pipes currently manufactured include extrusion press method that forms a narrow groove on the inner surface by extrusion press of soft metal such as aluminum and brass, and cutting method and drawing method that forms a narrow groove on the inner surface of the pipe by machining. There is a law.

However, in the extrusion press method, it is necessary to sufficiently resist this in order to receive the high pressure of the fluidized metal against a large number of thin protrusions for forming grooves inside the pipe in the die, A too thin protrusion cannot be formed. Therefore, in the conventional extrusion press method, it is difficult to narrow the width of the groove to an extremely fine width suitable for the liquid passage, and thus it is difficult to manufacture a heat pipe with good liquid transport efficiency. Further, the drawing method has the same problem as the extrusion pressing method on the die part.

Furthermore, the method of manufacturing a heat pipe by an extrusion press is not suitable for manufacturing a long heat pipe because of a structural problem of the mold. Further, the drawing method is not suitable for producing a long heat pipe in the same manner as the above method because a pulling force is applied to a thin pipe.

On the other hand, in the case of machining, it is difficult to manufacture a long heat pipe because the length of a cutting tool that cuts the groove is greatly limited, and it is practical to manufacture one having a delicate groove. Difficult to do.

Apart from the above technique, as a method of manufacturing a relatively long heat pipe, a method of filling the inside of a metal pipe with a metallic felt-like liquid-containing material has been proposed. However, when filling the inside of a small-diameter pipe with a felt-like material, the pressure to push the felt-like material into the interior is not transmitted, which is extremely difficult work. However, there is a problem in that it cannot be manufactured if it is too long. Also, if the felt-like material is forced into the pipe, the packing density will change, and the packing density will increase more than necessary especially at the inlet where the most force acts, and the function as a heat pipe will be significantly reduced. There is a problem to let it do.

Various types of heat pipe cross-sectional shapes have been proposed, but in JP-A-1-203894, all or a plurality of fins axially erected on the inner surface of a metal pipe are adjacent fins. It is bent with a distance that it does not touch,
A heat pipe has been proposed in which the width of the opening of the groove formed by this fin is smaller than the width inside the groove. Further, a method for casting a pipe by a heat casting method is disclosed in Japanese Patent Laid-Open No. 58-97.
Proposed by Japanese Patent No. 463.

The heat pipe having the above-mentioned structure has a structure capable of obtaining the maximum amount of heat of transport because the liquid passage and the gas passage can be separated from each other, but it is not possible to manufacture this structure by an extrusion method or machining. It's extremely difficult. Further, the method of producing a pipe in the heat casting method is excellent in that it can produce a pipe having an amorphous structure, but only a simple cross-sectional shape such as a circle is obtained, let alone No method has been proposed for producing a heat pipe in which a large number of fins are planted on the inner surface.

The present invention provides a method for solving all the problems of the extrusion method, the machining method, the drawing method and the filling method that have been conventionally adopted, and adopts a heating mold type continuous casting method. Therefore, it is an object of the present invention to provide a method for continuously and efficiently manufacturing a heat pipe, which is capable of continuously forming delicate groove portions and has excellent liquid transportation efficiency.

[Means for Solving Problems]

A method for manufacturing a heat pipe according to the present invention for achieving the above object is a method of casting a tubular body having a number of fins continuously formed in a longitudinal direction inside by a hot casting method, wherein a heater 8 is used. A heating mold 6 composed of an outer mold 4 and a core 5 is provided on the provided tundish 2, and these outer mold 4
The gap formed by the core 5 and the core 5 is a cylindrical portion and a protrusion 18 protruding from the inside of the cylindrical portion toward the outer peripheral direction.
Is formed in the lengthwise direction, and further, the protrusions 18 incline in the same direction in a diagonal direction toward the center in the cross section, and the cast heat pipe is a tubular portion 12a, and the inner surface of the tubular portion 12a is oriented in the central direction. This is a method of manufacturing a heat pipe (12) which is formed by fins (12b) that are inclined and protrude, and that have their tips closer to the root.

[Work]

When the heat pipe 12 having a large number of fins 12b on the inner surface of the tubular portion 2a is cast by the continuous casting method, a cylindrical portion is formed, and this cylindrical portion is formed from the inner peripheral direction to the protruding portion 18 of the core 5.
Since the fins 12b can be formed by cutting with, the manufacturing can be performed efficiently. Moreover, since the fins 12b are inclined in the inner diameter direction all at once, the fins 1b
It is possible to continuously manufacture the heat pipe 12 having a large moving heat amount, which has a delicate liquid passage having a long tip 2b and a reduced tip portion.

〔Example〕

 Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a heating mold type continuous casting apparatus, and this casting apparatus is proposed by, for example, Japanese Patent Laid-Open No. 58-97463.

In this casting apparatus, a melting pipe 3 is provided on one side of a tundish 2 covered with a heat insulating material 1, and a heating mold 6 composed of an outer mold 4 and a core 5 is provided at the bottom.

In the above apparatus, a metal material 7 such as copper, aluminum or brass is melted by a heater 8 in a melting pipe 3 and stored in a tundish 2 as a molten metal 9, which is melted between a core 5 and an outer die 4. Withdrawal device in succession from 10
The metal pipe 12 is continuously manufactured by drawing out the cooling water from the cooling nozzle 11 and then drawing it out while cooling.

FIG. 2 shows an example of the heating mold 6. The outer mold 4 has a cylindrical shape and has a step portion 15 on the upper part, and the step portion 15 has a support portion for the core 5.
A large number of protrusions 18 (portions forming grooves between fins) are provided so as to project around the body 17 while supporting the body 16.

FIG. 3 is a cross-sectional view showing an example of the metal tube 12 (material for the heat pipe) obtained by the casting apparatus, which is a tubular portion.
A large number of fins 12b are projected inside the 12a while being inclined in one direction, and a space 12c is formed at the tip of the fin 12b. Further, a groove 12d having a narrow width is formed between the fins 12b.

The metal tube 12 having the above structure, that is, the material of the heat pipe, is continuously cast by the hot mold casting method and cut into a predetermined size, for example, 500 mm.

Then, the rod-shaped molded body is press-fitted into the space portion 12c while being rotated in the direction in which the fin 12b is tilted, or a ball having a predetermined diameter is penetrated to deform the fin 12b. The heat pipe H processed and manufactured in this way is shown in FIG. 4. The fin 12b is tilted in one direction and its tip end is in contact with the side surface of the adjacent fin 12b. With this structure, as shown in FIG. 3, the groove 12d is closed from the open state of the tip of the fin 12b to form the closed groove 12e.

When the closed groove portion 12e is formed as described above, it is possible to move from one side to the other side due to the capillary phenomenon of the liquid (for example, water, alcohol, etc.) sealed in the metal tube 12.

The metal tube 12 cast by the heating mold type continuous casting method as described above, cut to a predetermined size, and processed with the fin 12b is closed at one end, is filled with a liquid inside, and is internally Is vacuumed and the other end is closed to produce the heat pipe.

In the heat pipe configured as described above, the closed groove 12e serves as a liquid passage (wick), and the closed groove 12e
The space 12c surrounded by e serves as a steam passage.

FIG. 5 shows a cross section of a part of another type of heat pipe H. FIG. 5 (a) shows that the thick groove 12g is formed at the tip of the fin 12b so that the closing groove 12e is crushed more than necessary. It has been prevented.

In the diagram (b), a thick portion 12g is formed at the tip of the fin 12b, and a branch portion 12h is further projected at the middle portion of the fin 12b. By forming the branch portion 12h in this manner, it is possible to divide the liquid passage into a plurality of passages.

〔The invention's effect〕

The heat pipe manufacturing method of the present invention is a method of casting a tubular body having a number of fins formed continuously in the lengthwise direction inside by a hot casting method, in which a tundish 2 provided with a heater 8 is provided with an outer mold 4. A heating mold 6 comprising a core 5 and a core 5 is provided, and a gap formed by the outer mold 4 and the core 5 is
A cylindrical portion and a protruding portion 18 projecting from the inside of the cylindrical portion toward the outer peripheral direction are formed in the lengthwise direction, and the protruding portion 18 further inclines in the same direction diagonally toward the center in the cross section. , The cast heat pipe has a tubular portion 12a,
From the inner surface of the tubular portion 12a, projecting with an inclination toward the center,
The heat pipe 12 is characterized in that the tip portion of the fin 12b is closer to the root portion than the root portion.

According to the present invention, when the heat pipe is manufactured by the heating mold casting method, the outer mold 4 and the core 5 are combined to form the molten metal into a cylindrical shape, and then the protrusions of the core 5 are arranged in the outer diameter direction from the inner diameter direction. The fins 12b are formed by cutting with the use of 18, and the fins 12b are formed in a state in which they are laid down at the same time, so that the inside of the heat pipe through which steam mainly passes and the outside diameter part through which liquid mainly passes are positively formed. It should be divided into two categories.

Specifically, as shown in FIG. 3, a plurality of rows of fins 12b are formed with a slight gap between the tips, and as shown in FIG. 4, tips of the rows of fins 12b are brought into contact with each other. Further, as shown in FIG. 5, a high performance device such as a heat pipe having a thick portion 12g at the tip of the fin 12b can be manufactured.

The method of manufacturing a metal tube having a special cross-sectional shape by a casting method can manufacture a small-diameter metal tube (heat pipe material) having high precision and fine fins as compared with the pressing method and the drawing method.

For example, the fins of the metal pipe obtained by the pressing method have the groove portions opened in a non-contact state with each other, so that only the liquid transport efficiency as the wick of the heat pipe is low. In particular, the height and thickness of the fins are important for exerting the function of the heat pipe, but in the extrusion press method, the thickness and thickness of the fins are caused by the fluidity of the metal and the frictional resistance between the mold and the mold. Only fins of similar height could be manufactured.

However, according to the present invention, the height of the fin is longer than that obtained by the conventional method if the metal tube has the same outer diameter as that described above, and the thickness of 1.2 mm and the thickness of 0.3 mm are continuously obtained. It is possible to manufacture. However, the fin formed so as to project inside the tubular portion in this manner is extremely excellent in workability because the closed groove portion can be formed simply by mechanically tilting it.

Further, it is possible to manufacture a core having a delicate projection. Specifically, the width of the closed groove portion of the heat pipe can be set to the micron order.

This makes it possible to manufacture a metal tube in which long and thin fins are densely arranged, which cannot be manufactured by the conventional method, and the fin is processed to form a liquid transport passage. Therefore, it is possible to highly efficiently manufacture a heat pipe having a high liquid transportation efficiency in which both the liquid transportation amount and the transportation distance are increased.

[Brief description of drawings]

1 shows an embodiment of the present invention, FIG. 1 is a schematic explanatory view of a heating mold type continuous casting method, and FIG. 2 is a sectional view showing an example of a heating mold. FIG. 3 is a cross-sectional view of a metal pipe (heat pipe material) manufactured by the heating mold, and FIG. 4 is a cross-sectional view of a heat pipe obtained by the present invention. 5 (a) and 5 (b) are main-portion cross-sectional views showing another cross-sectional shape of the fin provided inside the metal tube. 1 ... Insulation material, 2 ... Tundish 3 ... Melting tube, 4 ... Outer mold, 5 ... Core, 6 ... Heating mold, 7 ... Metal material, 8 ... Heater, 9 ... Molten metal, 10 ... Drawing device 11 …… Cooling nozzle, 12 …… Metal tube 12a …… Tube part, 12b …… Fin 12c …… Space part, 12d …… Groove part 12e …… Closed groove part, 12g …… Thick part 12h …… Branch part 15: Step, 16: Support 17: Body, 18: Projection

Claims (1)

[Claims] 1. A method of casting a tubular body having a number of fins formed continuously in the lengthwise direction by a hot casting method, wherein a tundish (2) provided with a heater (8) has an outer die (4). )
A heating mold (6) composed of a core (5) and a core (5) is provided, and a gap formed by the outer mold (4) and the core (5) is a cylindrical portion and an outer peripheral direction from the inside of the cylindrical portion. A projection (18) projecting toward the longitudinal direction is formed. Further, the projection (18) is inclined in the same direction in the cross section toward the center, and the cast heat pipe has a tubular portion ( 12a)
And a method for manufacturing a heat pipe (12) comprising a fin (12b) protruding from the inner surface of the tubular portion (12a) inclining toward the center and having a tip portion closer to the root portion.