JPS63317255A - Jointing method for closely packed multitube to porous metal member - Google Patents

Abstract

PURPOSE:To reduce a joining cost and to facilitate a work by coating the element executing an eutectic reaction with a metal or entering into solid solution at a low m.p. on the surface of a small diameter metal tube and heating the assembly joining face of a porous metal body and the small diameter metal tube at specified temp. CONSTITUTION:A thin Ag plated layer part is formed at both end parts of numerous small diameter metal tubes 1 and a small diameter tube 1 and metal body 2 are temporarily assembled by fitting it to the hole 4 of a porous metal body 2. In this case, a tube expansion work is executed according to the fitting state of the tube 1 and hole 4 to hold the fitting state well. The joining face is then heated at the temp. lower than the m.p. of the metal tube 1 and metal body 2 and higher than the m.p. of the eutectic body or a low m.p. solid solution. Therefore, the small diameter metal tube 1 and metal body 2 are strongly joined via the eutectic reaction or low m.p. solid solution formation. Consequently the joining cost is reduced and the joining work is facilitated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for assembling a tube assembly structure, such as a heat exchanger, in which a plurality of long small diameter tubes and a manifold need to be partially joined. It is related to.

[Conventional technology]

Conventional techniques include the following 2M1 joining method or derivative methods thereof.

(1) Method for soldering using flux or method for brazing (2) Method for fluxless brazing (however, a vacuum furnace or inert gas furnace is used, and the brazing method or brazing metal cladding method is used) ) [Problems to be Solved by the Invention] In (1) of the conventional bonding methods described above, it is difficult or impossible to completely remove fuwax after bonding, which may cause corrosion or damage to the surrounding area during use. This can cause problems due to reactions with the atmosphere, and the bond itself lacks reliability. Furthermore, in the joining method (2), when assembling a large number of pipes at high density, it is difficult to place and solder the pipes, and the finished joint is unreliable.

In particular, equipment used or loaded on space rockets,
Due to issues such as launch capability, there is a need for something that is lightweight, small, and as efficient as possible. In particular, in space, unlike on the ground, there is no convection, so the heat exchange function is particularly important. For example, in order to satisfy the above requirements, a heat exchanger used in outer space has a diameter of A5 m and a plate thickness of (125 m).
140 m, a small diameter pipe with a length of about 1000 cm within 1 m”
It is necessary to join the tubes to the manifold at an extremely high density of 00 tubes. For example, if you try to braze the conventional joining method using a brazing method, it is difficult to place the solder on the top and bottom of the pipe, and it takes time and effort to braze the top and bottom in sequence, and the pipes are not connected to each other. Because they are too close together, the melted brazing filler metal draws together due to its surface tension, causing the brazing filler metal to shift, resulting in some parts being brazed and some not, resulting in a problem that uniform brazing cannot be achieved over the entire heat exchanger.

[Means for solving problems]

The present invention has been made in order to solve the problems of the prior art as described above.The present invention has been made in order to (1) join a plurality of small diameter metal tubes to a porous metal member having a large number of closely spaced holes; A process of coating the joint surface of the small diameter metal tube with an element that forms a eutectic reaction or a low melting point solid solution with the porous metal member and the small diameter metal tube, and fitting the small diameter metal tube into the hole of the porous metal member. and temporarily assembling the temporarily assembled product at a temperature below the melting point of the small diameter metal tube and the porous metal member and above the eutectic temperature with the coating element or the melting point temperature of the low melting point solid solution. (2) A method for joining a plurality of small-diameter metal tubes to a porous metal member having a large number of closely spaced pores, the method comprising: heating the porous metal member; and a step of coating the joining surface of the small diameter metal tube with an element that undergoes a eutectic reaction or forms a low melting point solid solution with the small diameter metal tube, and after fitting the small diameter metal tube into the hole of the porous metal member. The process of expanding and temporarily assembling the temporarily assembled product is carried out at a temperature below the melting point of the small-diameter metal pipe and the metal member, and the eutectic temperature with the coating element or the melting point of the low-melting solid solution. This is a method for joining a close-fitting multi-tube to a porous metal member, the method comprising the step of heating to a temperature higher than the above temperature.

The present invention can be particularly advantageously applied to the joining of small diameter pipes and manifolds, which are indispensable for manufacturing the lightweight, compact, and highly efficient heat exchangers required for the above-mentioned space equipment.

[Effect]

Since the present invention is a type of fluxless brazing method with the above-mentioned configuration, even when manufacturing a structure in which a large number of small-diameter pipes are densely packed, the arrangement of elements equivalent to the brazing material is easy and reliable, and at the same time, it is possible to join. Since there is no need to remove fuwax afterwards, it is possible to significantly reduce costs and improve the quality and reliability of the joint.

Hereinafter, the means of the method of the present invention will be specifically explained.

First, a small diameter metal tube with a smaller outer diameter than the pore diameter of the porous metal member is prepared, and a eutectic reaction or a low melting point solid solution is applied to the part of the small diameter metal tube to be joined to the porous metal member. When coating the forming elements, these elements are coated using a plating method or CVD (chemical vapor deposition).
method, PVD (physical vapor deposition) method, etc.

These coating methods have the advantage that the range of coating and the thickness of the coating layer can be easily controlled.

If the precision between the small-diameter metal tube coated with all of the above elements and the hole in the porous metal member is poor, you can insert the small-diameter metal tube coated with the element into the hole in the porous metal member, and then expand the small-diameter metal tube. . Tube expansion methods include roller mant expansion, sleeve mandrel expansion, and pull-out or push-in tubes using alumina powder, rubber, etc.
This can be done by any means such as di-pressure tube expansion.

When the porous metal member and the small diameter metal tube (hereinafter referred to as the joining material) are aluminum (including alloys), copper, silver,
Coated with elements such as germanium and zinc. When the material to be joined is nickel/L/(including alloy), elements such as phosphorus, boron, cadmium, zirconium, magnesium, and chromium that can cause a eutectic reaction with nickel,
Coated with copper, gold, and other elements that form a solid solution with a lower melting point than nickel. Furthermore, when the material to be joined is niobium (including alloys), it is coated with elements such as phosphorus and nickel that can cause a eutectic reaction with niobium. Furthermore, when the material to be joined is titanium (including alloys), copper, nickel, and
Coated with elements such as silver.

After coating the surface of the joint of a small-diameter metal tube with such an element, the small-diameter metal tube is fitted into the hole of the porous metal member (or expanded after fitting), and the melting point is lower than the melting point of the materials to be welded, but is the same. heating to a temperature higher than the melting point of the crystal or low melting point solid solution;
Join the materials to be joined.

Hereinafter, the effects of the present invention will be demonstrated by citing the invention and development of the invention.

〔Example〕

This example shows an example of joining a porous aluminum member and a small diameter aluminum tube.

Fig. 1 (a) shows a small diameter aluminum tube 1, which is a small diameter tube with a wall thickness of α25-1, an outer diameter of 55 cm, and a length of approximately 1.000 mm, and is fitted into a hole in a porous aluminum member. Aj' plating with a thickness of 20 to 25 microns is applied to both ends (indicated by diagonal lines). 14,000 pieces of this material are manufactured and prepared.

FIG. 1(b) is a plan view of the porous aluminum member 2.
Figure (c) is a side view of the same, and this porous aluminum member 2 is 1000 m in length and width, the thickness part 3 of the joint part of the small diameter aluminum pipe 1 is 10 m, and it is an aluminum manifold having holes 4 (D number 14000i). , make and prepare two of these.

The 16,000 small-diameter aluminum tubes 1 prepared in this way were fitted into the holes 4 of the porous aluminum member 2,
Above the eutectic temperature of AL-Af (566°C), the melting point of At (
After heating to a temperature of 660°C or lower, cooling the
) I made a wooden structure like the one shown in the figure.

At this time, since the amounts of At and Ar involved in the eutectic reaction at the heating temperature can be determined from the AA-AP binary system equilibrium phase diagram, by controlling the thickness of the AP plating and the heating temperature, small diameter aluminum Required remaining wall thickness of pipe 1 (
Wall thickness that does not participate in eutectic reactions) can be easily controlled.

In addition, the holes 4 of the porous aluminum member 2 that will become the manifold
If the gap is too large or unmanageable due to the relationship between the accuracy of the pipe and the outside diameter of the small-diameter aluminum tube, it can be managed by using the various tube expansion methods described above. In this example, a pull-out rubber bulge pressure method was adopted, and as a result, excellent bonding properties were exhibited as shown in FIG. 2.

FIG. 2 is a microscopic photograph showing the joined state of the small-diameter aluminum pipe 1 made of one piece of wood and the holes 4 of the porous aluminum member 201 in the assembled tub structure using the method of the above-mentioned embodiment.
) is a microscopic photograph of the metal weave at a magnification of 100 times that of section ``2'' in FIG. 2(a).

In FIG. 2, 1 is a small diameter aluminum tube, 2 is a porous aluminum member, and 3 is an At-Ay eutectic weave.

Although examples have been given above of joining small-diameter aluminum pipes and porous aluminum members, excellent joining performance was also demonstrated by the method of the present invention in other combinations of small-diameter metal pipes and porous metal members.

〔Effect of the invention〕

The bonding method according to the present invention is a type of fluxless brazing method, but it is a method that causes a eutectic reaction with the base metal to perform bonding, which facilitates the brazing work before bonding, reduces the cost, and reduces the cost of plating. The amount of bonding reaction can be controlled by controlling the coating thickness and temperature, and the gap can also be easily controlled by expanding the pipe, making it possible to improve the quality and reliability of the bonded parts. At the same time, it is suitable for assembling aggregates that are assembled at high density.

[Brief explanation of drawings]

Micrograph (-Red #Concubine 100 times) divided by 10 times.

Claims (2)

[Claims] (1) When joining multiple small-diameter metal tubes to a porous metal member having a large number of densely packed pores, an element that forms a eutectic reaction or a low melting point solid solution with the porous metal member and the small-diameter metal tube is added to the joining surface of the small-diameter metal tubes. a step of temporarily assembling the small-diameter metal tube by fitting it into the hole of the porous metal member; and a step of temporarily assembling the small-diameter metal tube at a temperature below the melting point of the small-diameter metal tube and the porous metal member. A method for joining a dense multi-tube to a porous metal member, comprising the step of heating to a temperature higher than the eutectic temperature with the coating element or the melting point temperature of the low melting point solid solution. (2) When joining multiple small-diameter metal tubes to a porous metal member having a large number of densely packed pores, an element that forms a eutectic reaction or a low melting point solid solution with the porous metal member and the small-diameter metal tube is added to the joining surface of the small-diameter metal tubes. a step of fitting the small-diameter metal tube into the hole of the porous metal member and then expanding the small-diameter metal tube to temporarily assemble it; and a step of temporarily assembling the small-diameter metal tube and the porous metal member; A method for joining a close-fitting multi-tube to a porous metal member, comprising the step of heating to a temperature below the melting point of the member and above the eutectic temperature with the coating element or the melting point temperature of the low melting point solid solution. .