JPS61232060A - Production of multi-hole tube for aluminum heat exchanger - Google Patents

Abstract

PURPOSE:To prevent the buckling of fins in the stage of brazing the bare fins by coating a potassium fluoroaluminate complex salt flux to the surface of an extruded multi-hole tube made of Al or Al alloy and preheating the tube then dipping the tube into the melt of an Al-Si alloy brazing filler metal having the m. p. below the m. p. of the multi-hole tube and subjecting the surface to hot dipping. CONSTITUTION:The potassium fluoroaluminate complex salt flux is coated on the surface of the extruded multi-hole tube 1 made of the Al or Al alloy having >=635 deg.C m. p. and thereafter the tube is preheated to 100-500 deg.C and is dipped into the melt of the Al-Si alloy brazing filler metal kept at <=630 deg.C so that the Al-Si brazing filler metal 3 is hot dipped on the surface of the tube 1. The assembly of a heat exchanger core by combining such tube with the bare fins 2 and by ordinary brazing is thus made possible without using the fins consisting of a brazing sheet and without buckling the fin 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a tube for circulating a heat exchange medium in an aluminium π heat exchanger which is assembled by a brazing method.

Conventional technology Generally, aluminum heat exchangers are used in oil coolers and radiators for automobile and aircraft engines, as well as evaporators and condensers for air conditioners. As shown in Figure 3, bend the tube into a meandering shape (1
) A full gate fin (2) made of a plating sheet coated with Al alloy brazing filler metal on both sides is attached between the fins (2), and this is heated to the melting temperature of the brazing filler metal and brazed to assemble the aluminum heat exchanger tray. ing.

Problems to be Solved by the Invention In recent years, there has been a strong desire to reduce the weight of heat exchanger fins from the standpoint of energy saving and cost reduction, and thinning of the fins is being considered. However, during brazing work, in order to improve the joint between the tube and fin, both
Brazing is performed by fixing with an iron jig in the direction of the arrow shown in the figure. Therefore, the tube and fin have Ai and F.
Due to the high stress caused by the difference in thermal expansion of e, if the fin thickness is made thinner than the current approximately 0.1θ■, the fins may buckle during brazing, which deforms the entire heat exchanger and makes installation difficult. Because of this, it was extremely difficult to reduce the thickness of the fins, that is, to reduce the weight of the heat exchanger air.

Means for Solving the Problems In view of this, the present invention has conducted various studies and found that buckling of fins during brazing can be solved by using normal brazing in combination with bare fins, without using fins made of plating sheets. The method is characterized in that a potassium fluoroaluminate complex flux is applied to the surface of an extruded porous tube made of an An or Al alloy with a size larger than fins, and then the material is hot-dip plated at 100 to 500°C. Melting point is 63
As Al or Al alloy at 0°C or higher, for example, JIS
105G (Pure A i of 98.5% or more pure soap) JIS
Iloo (A i -0.05~0.20% Cu alloy') JIS3003 (A l -0.05~0.
20%Cu-1.0~1.5%M lazy alloy) JIS
3203 (Al-1.0 to 1.5% Mn alloy), etc., is extruded into a porous tube according to a conventional method, and the tube surface is treated with a solvent or detergent before applying potassium fluoroaluminate complex flux. Apply potassium fluoroaluminate powder or as an aqueous solution in water. Also, as an An-5i alloy brazing material.

An alloy consisting of SI 8-13%, balance Ai and unavoidable impurities, such as JIS4343 (A i -6,8~B,
2%Si alloy) JISt045 (A l-9,0
~11.0%Si alloy) JIS4G4? (A i
Zn, Sn.

An An-Si alloy brazing filler metal to which any one type of In or 29 or more is added is used.

Function In the present invention, the extruded multi-hole tube is f! The reason why Al or Al alloy with a temperature of 35°C or higher was used was to make the hot-dip plating of the above-mentioned A-Si-based alloy brazing material more stable, and the melting point was 63°C.
This is because if the temperature is lower than 5° C., a portion of the tube will be deformed or melted, making hot-dip plating difficult. In addition, the reason why potassium fluoroaluminate complex flux is applied to the tube surface is to wet the tube surface and the brazing metal well during hot-dip plating to form a good plating layer of the brazing metal.
Moreover, this flux is non-corrosive and requires no removal treatment after hot-dip plating, and since the flux melts before the work begins, the tube does not get wet well.If the temperature exceeds 500℃, the quality of the flux deteriorates during preheating, and 7 lux 63 during hot-dip plating.
If the temperature exceeds 0°C, part of the tube will deform or melt.

A multi-hole tube for an aluminum heat exchanger, in which the surface of an extruded multi-hole tube made of An or A2 alloy is hot-dip-plated with an An-3I alloy brazing filler metal, is made into a multi-hole tube (as shown in Fig. 1). The surface of 1) is filled with brazing metal (3)
When installing full gate fins between tubes that are covered with a serpentine fin and bent into a serpentine shape, it is possible to use normal brazing in combination with bare fins without using a fin made of a plating sheet with brazing metal coated on both sides. 1. For example, the aluminum heat exchanger 1A can be assembled by the FB method using a cement-based flux or the NE method using a potassium fluoroaluminate complex-based flux. As a result, even when the fins are brazed, the decrease in strength is small, and buckling of the fins can be effectively prevented. Also, set the fin thickness to 0.
．． It is possible to make the heat exchanger as thin as 0.8m, making it possible to make a significant contribution to reducing the weight of the heat exchanger.

Example Apply a 10% aqueous solution of non-corrosive flux containing JISI050 (melting point: 848°C) as the main component to normal extrusion processing, preheat under the conditions shown in Table 1, and then apply JIS 4045 of 820°C. g for 10 seconds into the molten material
Hot-dip plating was performed by dipping to produce a multi-hole aluminum heat exchanger tube as shown in FIG.

After observing the plating condition of these tubes, they were bent into a meandering shape as shown in Figure 3, a bare full gate fin made of J1S3003 with a thickness of 0.08 m was attached between the tubes, and the tubes were exposed to upper air. This was heated to 610° C. for 10 minutes and brazed to produce a heat exchanger 1A. The brazing properties and buckling resistance of these were investigated. These results were bent into a serpentine shape without hot-dip plating a brazing material on an extruded multi-hole tube made of JIS1050.

A conventional heat exchange method in which a corrugated fin made of a plating sheet of the thickness shown in Table 1 is attached between the tubes and a core material made of JIS 3003 is coated with a brazing material made of JIS 4045 on both sides, and brazed in the same manner as above. The results are shown in Table 1 in comparison with the container 1a.

As is clear from Table 1 and Table 1, J with a melting point higher than 835°C
Apply potassium fluoroflumate salt-based flux to the surface of an extruded multi-hole tube made of IS1050, 1
The multi-hole tubes for heat exchangers manufactured by the method of the present invention (Ml) 1 to 5), which is preheated at 00 to 500"O and immersion plated in molten steel at 630℃ or less according to JIS 4045, are plated. The heat exchanger 1A using this had good brazing properties and no buckling was observed on the fins.In contrast, the comparative method Nb8-7 in which the preheating was less than 100"O And multi-hole tubes for heat exchangers manufactured by Comparative Methods No. 8 to 8 in which the preheating temperature exceeds 500"C could not achieve a good plating condition, and brazing was difficult in heat exchanger 1A using these tubes. In addition, as is clear from the conventional method No. 1 O-12, in which the surface of a multi-hole tube for a heat exchanger is not coated with a brazing material and is combined with a fin made of a plating sheet, To prevent fin buckling, the fin thickness must be at least 0.18s.
It turns out that it is necessary to set the value to - or more.

In addition, using JIS3003 (melting point 843°C) caranal extruded porous tube, JIS was applied to the An-Si alloy brazing material.
Using S4343 and JrS4047, Al-3i alloy was applied to the surface of a multi-hole tube for a Nishite heat exchanger, but the results were almost the same as above.

Effects of the Invention According to the present invention, it is possible to easily obtain a multi-hole tube for an aluminum heat exchanger in which an extruded multi-hole tube is coated with a good brazing material hot-dip plating, and furthermore, even if the fins are thinned, Brazing can prevent the fins from buckling over time, and has significant industrial effects, such as making it possible to reduce the weight and cost of heat exchangers.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an example of an aluminum multi-hole tube for a heat exchanger manufactured by the method of the present invention, Fig. 2 is a perspective view showing an example of a conventional aluminum multi-hole tube for a heat exchanger, and Fig. 3 is a perspective view showing an example of a conventional multi-hole aluminum heat exchanger tube. FIG. 2 is a perspective view showing an example of an aluminum heat exchanger. 1 Extruded multi-hole tube 1a hole 2 Corrugated fin 3 A-cross alloy brazing filler metal

Claims (1)

[Claims] After coating the surface of an extruded multi-hole tube made of Al or Al alloy with a melting point of 635°C or higher, a potassium fluoroaluminate complex flux is preheated to 100 to 500°C to form an Al-Si immersed in a melt of 630°C or less alloy brazing filler metal,
A method for producing multi-hole tubes for aluminum heat exchangers, which is characterized by hot-dip plating a brazing filler metal on the tube surface.