JPH01130870A - Manufacture of aluminum made heat exchanger - Google Patents

Abstract

PURPOSE:To subject bending part and linear part to work hardening and to improve the pressure resistant strength by stretching in parallel to the linear part of a perforated pipe with the inside of the bend part of the perforated pipe of the heat exchanger brazing a corrugated fin by heating it to the Al made extrusion perforated pipe which is bent in meandering shape as the fulcrum. CONSTITUTION:The corrugated fin 2 composed of the brazing sheet to which a brazing filler metal is cladded is assembled into the Al made extrusion perforated pipe 1 bent in meandering shape and a core assembly is made by interposing it by a pressing jig. After executing zincate treatment by degreasing it a flux is coated and brazing by heating is executed in N2, etc. It is subjected to stretching to the core outside in parallel to the linear part of the perforated pipe 1 with the inside of the bend part 4 of the perforated pipe 1 as the fulcrum by jigs 5, 6 by fitting a jig 5 to the inside of the bend part 4 and a jig 6 to the inside of an union 3. The bending part and linear part are thus subjected to work hardening by applying stretching on the perforated pipe subjected to an O materializing by heat brazing, the pressure resistant strength is improved and the lightening of a core can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing an aluminum heat exchanger, and particularly to a method for improving the compressive strength of a serpentine type heat exchanger.

(Prior art) There are serpentine type condensers and evaporators as aluminum heat exchangers, and these use extruded aluminum multi-hole tubes that constitute refrigerant passages and fins made of a blending sheet clad with brazing material. , made using the brazing method. As an extruded multi-hole tube, it has a flat shape.
Approximately 4 to 8 holes are used for the condenser, and 15 to 30 holes are used for the evaporator, each with a width of 2.
Generally, it is 2m, around 100Mr1, the height (thickness) is 5m, and the wall thickness is 0.4 to 1.0#. Furthermore, a brazing sheet with a thickness of approximately 0.16 seconds is used for the fins.

At first, the mainstream brazing method was to use chloride-based flux and heat it in the atmosphere (FB method), but due to problems such as drainage treatment, it was decided to do so in a vacuum without using 7lux. The brazing method has changed to one in which the material is heated in N2 gas (the NB method) using a non-corrosive fluoride flux (the VB method).

NB method is JIS 1050.1070.1 for extruded multi-hole pipes.
Using A1 or A1 alloy such as 100°3003, the fin is made of JIS 3003 + 1.5% 7-n alloy as the core material,
Using a brazing sheet clad with JIS 4343 brazing material on both sides, a corrugated fin is installed between the extruded multi-hole tubes bent into a serpentine shape by a bender, and a union is attached to the end of the extruded multi-hole tube. After mounting, assemble the core by holding it with a holding jig, degrease it and treat it with zincate, apply flux, and then apply N.
The end plate is attached to the side of the core by heating and brazing in two gases.

[Problem that the invention seeks to solve]

The manufactured heat exchanger is required to have a pressure resistance of 100 Kg/CI/ or more for condensers and 40 Kg/cM or more for vaporizers according to the pressure vessel standards, so the cross-sectional shape of the extruded multi-hole tube after brazing is 0 material strength exceeds this standard.

However, extruded multi-hole tubes are JIS IX with excellent hot extrudability.
The main types are XX series and JIS 3XXX series, and the strength obtained by brazing heating is only about 7 to 12 kg/-.The cross-sectional shape of the extruded multi-hole pipe is determined based on this O material strength, and the thin wall of the multi-hole pipe is determined based on the O material strength. There were limits to this.

On the other hand, the only way to make a multi-hole pipe thinner is to reduce the hole size to prevent the pressure resistance from decreasing.
, 4mm, considering that the limit is 0.4#,
At present, the thickness is progressing to a point close to this. Also, in order to reduce the resistance of the passageway, we are in a situation where it is not possible to narrow the width very much.

In particular, in serpentine-type heat exchangers, the tube wall becomes noticeably thinner at the bent portions, and these portions often break during pressure tests, so there is a strong desire to improve the pressure resistance of multi-hole tubes.

(Means for Solving the Problems) In view of this, and as a result of various studies, the present invention is an aluminum heat exchanger in which the extruded multi-hole pipes are made harder after heat brazing, and the pressure resistance of the multi-hole pipes is improved. A manufacturing method has been developed in which the refrigerant passage is an extruded multi-hole Ai tube bent in a serpentine shape.
In the manufacture of heat exchangers, corrugated fins made of brazing sheets clad with brazing material are incorporated between bent multi-hole tubes to form a C core, and this is heated and brazed. Using the inside of the bend as a fulcrum,
This method is characterized by applying stretching deformation to the outside of the core parallel to the straight portion of the multi-hole tube.

That is, the present invention is directed to an Ai bent into a meandering shape as shown in FIG.
A corrugated fin (2) made of a brazing sheet clad with brazing material is installed between the extruded multi-hole pipes (1), and although not shown in the figure, the core is assembled by holding it with a holding jig. Attach unions (3) to both ends of pipe (1). After degreasing and zincate treatment, flux is applied and then heated and brazed in N2 gas.

As shown in the figure, the bent part (4) of the multi-hole pipe (1)
jig (5) inside the union (3) and jig (6) inside the union (3).
), and use cough jigs (5) and (6) to connect the multi-hole pipe (1).
), using the inside of the bent part (4) as a fulcrum, and stretching the core outward (in the left-right direction in the figure) parallel to the straight part of the multi-hole tube (1).

(Function) The heat exchanger of the present invention applies a stretching process to a multi-hole tube that has been heat-brazed to form O phase, thereby work-hardening the bent portions and straight portions of the multi-hole tube, improving its pressure resistance. let For example, in the case of JIS 1050 alloy, as shown in FIG. 2, the yield strength improves depending on the degree of working (elongation), and the pressure resistance strength increases.

However, the core is made by stretching the multi-hole tube from side to side.
In order to prevent shrinkage in the vertical direction, it is necessary to adjust the width to the four methods of each jig, especially the spacing of the multi-hole tubes. Furthermore, as shown in FIG. 3, the jigs (5) and (6) must be positioned relative to each other using guides (7). In the figure, arrows indicate the movable direction and range of the jig.

Further, as the multi-hole tube deforms, the pitch of the fins also increases because the interval between the fins and the joint with the multi-hole tube increases, so it is necessary to reduce the pitch of the fins in advance during corrugation processing of the fins. Reducing the pitch of the fins has an advantageous effect on buckling of the fins during brazing. Furthermore, since the multi-hole tube reduces its width and height as it stretches and deforms, the multi-hole tube is made thicker in advance in anticipation of this reduction. Furthermore, the reduction in the width and height of the multi-hole pipe also reduces the internal dimension, which improves the pressure resistance of the multi-hole pipe.

(Example) A 4-hole condenser tube made of JIS 1050 alloy with a width of 16 m, a height of 5 feet, and a wall thickness of 0.8 m was made.
Bent processing was performed in a serpentine shape at intervals of m. Also JIS 30
The fin material was a brazing sheet with a width of 16# and a thickness of 0.16an, which was made by cladding 10% brazing material made of JIS 4343 alloy on both sides of a 03 alloy plate, and was corrugated to create a fin with a pitch of 3 and a height of 16. . These fins were assembled between the tubes of a meandering bent condenser tube to form a core, held by a holding jig, and heated and brazed by the NB method. That is, after degreasing,
After zincate treatment, 3% fluoride flux was applied thereto, and after drying, heat brazing was performed at 600° C. for 10 minutes in N2 gas. The union was made of JIS7NO1 alloy and was attached to both ends of the condenser tube by TIG welding before NB brazing.

Using the serpentine type capacitor thus formed, a jig was attached to the inside of the bent part of the duplex and the inside of the union as shown in Figure 1, and a
．． A stretching process of 5 to 3% was applied, and a pressure test was conducted using water pressure to determine the bursting pressure. The results are shown in Table 1. The pressure resistance in the table is the average value of 5 test results.

Table 1 As is clear from Table 1, according to the method of the present invention, work hardening and change in cross-sectional shape (reduction) of the condenser tube
It can be seen that the compressive strength is improved by 10 to 20% due to the synergistic effect of .

The change in heat exchange performance due to stretching of the duplex was investigated, but no difference was observed in heat exchange performance due to stretching.

〔Effect of the invention〕

According to the present invention, it is possible to improve the pressure resistance strength of a serpentine type heat exchanger.
Since the pressure resistance is improved by ~20%, even if the wall thickness of the extruded multi-hole tube is reduced by 10 to 20%, the pressure resistance of the heat exchanger manufactured using the conventional method can be obtained, and the weight of the core can be reduced. , which has significant industrial effects.

[Brief explanation of the drawing]

Fig. 1 is an explanatory drawing showing an example of the present invention, Fig. 2 is a graph showing the relationship between the working degree (elongation) and proof stress of O material, and Fig. 3 is an explanatory drawing showing an example of the guide of the stretching jig. be. 1, extruded multi-hole tube 2, fin 3, union 4, bent portion 5.6. Enlarger jig 7, guide

Claims (1)

[Claims] An extruded multi-hole aluminum tube bent into a meandering shape is used as a refrigerant passage.
In the manufacture of heat exchangers, corrugated fins made of brazing sheets clad with brazing material are incorporated between bent multi-hole tubes to form a core, and this is heated and brazed. Using the inside of the bend as a fulcrum,
A method for manufacturing an aluminum heat exchanger, characterized by applying stretching deformation to the outside of the core parallel to the straight portion of a multi-hole tube.