JP2000220899A - Manufacture of cold head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a cold head with further improved characteristics by welding a cylinder pipe where a displacer including a heat exchanger is reciprocated inside to a cylinder holder that functions as a heat radiation part and performing the honing of the inner surface of the welded cylinder pipe and cylinder holder. SOLUTION: When a cold head 11 is to be manufactured, a cylinder pipe 21 is welded to a cylinder holder 23 before honing, thus eliminating a part or the like deviating from a round due to welding and at the same time setting the inner surface of the cylinder pipe 21 to a surface with a proper roughness. When honing is made so that the surface roughness becomes approximately 1.3-1.9 S by manufacturing the cold head 11 due to a procedure using the cylinder pipe 21 that is made of an SUS seamless pipe with a surface roughness of 3.2 S, the cold head 11 indicating improved characteristics can be obtained. On the other hand, when honing is made so that a surface roughness of approximately 1.6 S is obtained, the cold head 11 indicating especially improved characteristics can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a cold head for a small Stirling refrigerator.

[0002]

2. Description of the Related Art As is well known, a cold head (expansion part) for a small Stirling refrigerator includes a displacer functioning as a regenerator and a pressure vessel in which the displacer reciprocates inside. A displacer is manufactured by combining a cylinder pipe that slides on its inner surface, a cylinder holder that functions as a heat radiator, and the like.

[0003]

In order to obtain a cold head exhibiting good characteristics, the friction coefficient between the displacer and the cylinder pipe is small and the leak is small (whole surface or a part of the displacer (for example, at two places). )
The sealing effect of the sealing surface provided on the cylinder pipe is large. In order to reduce the friction coefficient, it is necessary to make the inner surface roughness of the cylinder pipe appropriate, and to reduce the leak, it is necessary to improve the roundness of the cross section of the cylinder pipe.

[0004] On the other hand, when a cold head (pressure vessel) is manufactured, a work of welding a cylinder pipe made of stainless steel to a cylinder holder usually made of copper is usually performed. For this reason, although there is a degree of variation depending on the operation procedure (contents), in the conventional manufacturing method,
A pressure vessel having a deformed portion, a step, or the like near a welded portion, that is, a pressure vessel that can provide a cold head that does not exhibit good characteristics has been manufactured.

Accordingly, an object of the present invention is to provide a method of manufacturing a cold head which can obtain a cold head exhibiting better characteristics.

[0006]

According to the present invention, there is provided a method for manufacturing a cold head, comprising: a displacer including a heat exchanger; a cylinder pipe reciprocating therein; and a cylinder functioning as a radiator. The method includes a welding process of welding the holder and a honing process of honing the inner surfaces of the cylinder pipe and the cylinder holder welded by the welding process.

That is, in the manufacturing method of the present invention, by performing the honing process after the welding process, the roundness of the cylinder pipe deteriorated by the welding process is improved, and the inner surface roughness is reduced to a small friction coefficient. Make the roughness. According to this manufacturing method, a pressure vessel having a high roundness and an appropriate inner surface roughness can be obtained, so that a cold head having a smaller coefficient of friction between a displacer and a cylinder pipe and a smaller leak than before can be obtained. That is, it is possible to manufacture a cold head exhibiting better characteristics than before.

When the manufacturing method of the present invention is carried out, it is preferable to use, as the honing step, a step in which the inner surface of a cylinder pipe or the like after the welding step has a roughness of 1.3S to 1.9S. The inner surface has a roughness of about 1.6S.
It is desirable to use the step of

[0009]

Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 shows the configuration of a cold head manufactured by the manufacturing method of the present invention. As is apparent from the figure, the cold head 11 manufactured by this manufacturing method is used.
Is used in a split-type Stirling refrigerator, and includes a cylindrical displacer 20 containing a cold storage material (such as a wire mesh) for heat exchange, and a cylinder pipe 21 in which the displacer 20 reciprocates. The cold head 11 includes a cold tip 22, a cylinder holder 23, a holder cap 24, and a coil spring 25.
And The cold tip 22 is a cylinder pipe 2
1 is a member having a shape capable of closing one end of
It is fixed to the cylinder pipe 21 by silver brazing or the like.
An object to be cooled is attached to the cold chip 22.

The cylinder holder 23 holds the cylinder pipe 2
1 has a columnar cavity 60 fixed by silver brazing or the like, and a cavity 61 for connecting the columnar cavity 60 to the compressor via the capillary tube 12. The holder cap 24 is fixed to the cylinder holder 23 by bolts 28 with the seal member 27 interposed therebetween, so that the holder cap 24 communicates with the outside world (a compressor not shown) only through the capillary tube 12 in the cold head 11. To form a closed space. The holder cap 24 has a shape that functions as a spring seat for a coil spring 25 for keeping the displacer 20 at a neutral point.

In the manufacturing method according to the present invention, when manufacturing the cold head 11, the cylinder holder 23
Then, after the cylinder pipe 21 is welded, honing is performed to eliminate a portion deviated from a perfect circle due to welding, and to make the inner surface of the cylinder pipe 21 a surface having an appropriate roughness.

The production of the cold head 11 according to the above-described procedure using a cylinder pipe 21 made of a SUS seamless pipe having a surface roughness of 3.2S has a surface roughness of 1.3.
When the honing is performed to about 1.9S, a cold head 11 showing good characteristics is obtained. When the honing is performed to about 1.6S, the cold head 11 showing particularly good characteristics is obtained. Make sure you can.

[0014]

According to the manufacturing method of the present invention, a pressure vessel having a high roundness and an appropriate inner surface roughness can be obtained, so that the friction coefficient between the displacer and the cylinder pipe is smaller than in the prior art, In addition, it is possible to manufacture a cold head having less leakage, that is, a cold head exhibiting better characteristics than the conventional one.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cold head manufactured by a manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Cold head 12 Capillary tube 20 Displacer 21 Cylinder pipe 22 Cold tip 23 Cylinder holder 24 Holder cap 25 Coil spring 27 Seal member 28 Bolt

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshio Uchida 2-1-1 Tanidocho, Tanashi-shi, Tokyo Sumitomo Heavy Industries, Ltd. Tanashi Works (72) Inventor Yoshito Taguchi 2-chome, Tanatocho, Tanashi-shi, Tokyo No. 1-1 Sumitomo Heavy Industries, Ltd. Tanashi Factory

Claims (3)

[Claims] 1. A method of manufacturing a cold head for a small Stirling refrigerator, comprising: a welding step of welding a cylinder pipe in which a displacer reciprocates inside and a cylinder holder functioning as a heat radiating part; A honing step of honing an inner surface of a cylinder pipe and a cylinder holder welded by the above method. 2. The method according to claim 1, wherein the honing step is a step of setting the roughness of the inner surface to 1.3S to 1.9S. 3. The method according to claim 1, wherein the honing step is a step of reducing the roughness of the inner surface to about 1.6S.