JP3090772B2 - Brazing method for aluminum parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The method of brazing aluminum parts according to the present invention is incorporated in, for example, an air conditioner for automobiles to produce an evaporator for cooling air for air conditioning in a passenger compartment. Use in cases.

[0002]

2. Description of the Related Art An air conditioner incorporates an evaporator for evaporating a refrigerant inside and cooling air flowing outside. Built into such an air conditioner,
Conventionally, as a heat exchanger used as an evaporator, for example, Japanese Patent Application Laid-Open No. 61-49995 discloses a heat exchanger as shown in FIG.
Nos. 4 to 4 disclose a laminated evaporator.

The laminated evaporator is made of aluminum or an aluminum alloy (these materials are collectively referred to as "aluminum material" in this specification), and a pair of protruding ends is provided at one edge thereof at intervals. Part 1a, 1
An inverted U-shaped concave portion 3 is formed on one surface of the plate member 2 on which b is formed, with both ends of the concave portion 3 continuing to the edges of the pair of protrusions 1a and 1b. A large number of protrusions 4 are formed inside the concave portion 3 to disturb the flow of the refrigerant flowing inside the return flow path formed by the concave portion 3, and the heat exchange between the refrigerant and the plate 2 is efficient. Try to do well.

In the case of a laminated evaporator manufactured using such a plate member 2, the plate members 2 are formed as a set of two sheets, and are superposed in the middle while the recesses 3 are opposed to each other. The elements 6, 6 having an inverted U-shaped folded flow path and a pair of bonding parts 5a, 5b located at both ends of the flow path and protruding from the edge by being joined together in a liquid-tight manner. And

The joints 5a and 5b of the plurality of elements 6 and 6 are inserted into slit-like connection holes 9 and 9 formed on the upper surfaces of the first and second tanks 7 and 8, respectively. , The outer peripheral surface of each joint 5a, 5b and each connection hole 9,
9 and the inner peripheral edge are brazed to each other in a liquid-tight manner. Each of the tanks 7 and 8 is constituted by combining a seat plate 10 and a tank main body 11 as shown in FIG. 4 and brazing them to each other in a liquid-tight manner. 10
Is formed. Also, between the adjacent elements 6, 6
Fins 12 are provided.

The inside of the first tank 7 is divided into an inlet chamber 14 and an outlet chamber 15 by being partitioned by a partition wall 13 fixed to an intermediate portion.
The refrigerant outlets 17 are provided on the outlet chamber 15 side, respectively, until the refrigerant sent from the refrigerant inlet 16 flows through the return flow path in each element 6 and 6 and is taken out from the refrigerant outlet 17. During the evaporation.

By the way, when manufacturing a laminated evaporator configured and operating as described above, the plurality of elements 6,
6, the fins 12, 12, the first and second tanks 7, 8 and the partition 13 are combined in a state shown in FIG. 3 and temporarily fixed by a jig (not shown). 8
Is heated in a heating furnace.

The plate members 2 constituting the plurality of elements 6, 6
2 is made of a so-called clad material in which a clad layer also made of an aluminum brazing material is formed on both sides of a core material made of an aluminum material. Are melted and cooled and solidified again, the plate members 2 and 2 constituting the plurality of elements 6 and 6 as well as the elements 6 and 6 and the fins 12 and 12 and the first and second tanks 7 and 8 are formed. , First and second tanks 7,
The seat plate 10 and the tank main body 11 that constitute the part 8 are brazed to the first tank 7 and the partition wall 13, respectively.

As described above, the plate members 2, 2, the element 6,
6. When brazing aluminum parts such as the first and second tanks 7 and 8, the seat plate 10, the tank body 11, the partition wall 13 and the like to each other, the oxide layer existing on the surface of each part is destroyed. In order to ensure good brazing, a flux is applied to a contact portion between components. As such a flux, for example, a fluoride-based flux described in Japanese Patent Publication No. 58-27037 is widely used because it does not generate corrosive residues after brazing.

[0010] It is also possible to use a high-viscosity polybutene as a dispersion medium for the flux so that the flux can be applied only to the required portions.
As described in JP-A-794-6 / 1994, it is conventionally known.

[0011]

However, when aluminum materials are brazed to each other by using a fluoride-based flux as a flux and polybutene as a dispersion medium, a black residue remains at the brazed portion. Occurs, and the residue may reduce the brazing strength.

That is, polybutene used as a flux dispersion medium depolymerizes and sublimates at about 300 ° C., which is lower than the brazing temperature (for example, around 600 ° C.). It floats around. On the other hand, when the fluoride-based flux is activated based on heating, HF gas is generated. When the HF gas and the hydrocarbon gas are simultaneously present in a heating furnace for brazing, the hydrocarbon gas is generated. The bond between the C-Hs inside is broken, and a fine powder of carbon (C) is generated. When the fine powder adheres to the brazing portion, it causes the above-mentioned brazing failure.

The method for brazing aluminum parts according to the present invention prevents the above-mentioned generation of fine carbon powder,
This prevents the occurrence of brazing defects.

[0014]

According to the method of brazing aluminum parts of the present invention, the parts are brazed and joined to each other in the same manner as the above-mentioned conventional method of brazing aluminum parts. On the surface of at least one of the plurality of aluminum parts,
After applying a fluoride-based flux using polybutene as a dispersion medium and combining the plurality of aluminum parts with a brazing filler metal interposed between their contact surfaces, the plurality of aluminum parts are combined. The parts made of aluminum are heated in a heating furnace having a non-oxidizing atmosphere to melt the brazing material, and the plurality of parts made of aluminum are brazed to each other.

[0015] In particular, in the method of brazing aluminum parts of the present invention, at least a temperature higher than the sublimation temperature of polybutene and lower than the temperature at which the fluoride-based flux becomes active is obtained. The heating rate in the heating furnace is regulated at 19 to 25 ° C./min.

[0016]

In the brazing method of the present invention, the flux is activated after the polybutene used as a dispersion medium of the flux sublimates to generate a hydrocarbon gas. Sufficient time exists between the formation of HF gas and the formation of HF gas. For this reason, the hydrocarbon gas generated by the sublimation of polybutene is removed from the surroundings of the aluminum component before the HF gas is generated.

Therefore, the hydrocarbon gas and the HF gas do not exist at the same time in the vicinity of the brazing portion of the aluminum component, and the hydrocarbon gas and the HF gas react with each other to produce carbon fine powder. Disappears. For this reason, a brazing defect does not occur due to the carbon fine powder, and a brazing product made of an aluminum material having sufficient strength can be obtained.

[0018]

EXAMPLES The following tables and FIGS. 1 and 2 show the results of experiments conducted by the present inventors to confirm the effects of the present invention.

[0019]

[Table 1]

FIGS. 1 and 2 show the relationship between the elapsed time after the parts made of aluminum material to be brazed and joined into the heating furnace and the temperature in the heating furnace. This figure 1
Shows the relationship between the temperature rise speed represented by the inclination angle of the curve described in Table 1 and the adhesion rate, respectively. The heating speed 5 in each drawing is the same as that of Comparative Example 1 in the above table.
Corresponds to Comparative Example 2, temperature rising speed 3 corresponds to Comparative Example 3, temperature rising speed 4 corresponds to Example 1, and temperature rising speed 5 corresponds to Example 2.

As the fluoride-based flux used for the brazing, the one described in the above-mentioned JP-B-58-27037 and commercially available as "NOCOLOK FLUX" was used. The heating brazing was performed in a nitrogen gas atmosphere under the conditions of a dew point of -30 ° C., an oxygen concentration of 10 p.pm or less, and a heating temperature × time = 600 ° C. × 3 min.

Further, the brazing property was evaluated by visually observing the bonded portion after brazing, and the bonding ratio was described in the above table. The adhesion ratio is defined as a percentage (100 L ₁ / L) of a length L ₁ of a fillet formed between the components by heat brazing with respect to a contact length L ₀ of the components to be brazed to each other. ₀ ).

As is clear from these tables and the description of FIGS. 1 and 2, the heating rate in the heating furnace was set at 19 to 25 ° C., as in the method of brazing aluminum parts of the present invention.
If the rate is regulated to / minute, a fillet is formed over the entire length of the brazing portion. The heating rate in the heating furnace was set to 19 ° C.
Even if it is less than / min, the brazing property does not improve any more, it only increases the time required for brazing, and it causes Si and Zn contained in the aluminum material to diffuse. Is not preferred.

[0024]

The method for brazing aluminum parts of the present invention is constructed and carried out as described above, so that the brazing property is good and a sufficient heat-exchanger such as a heat-exchanger having excellent pressure resistance is provided. An aluminum brazing product having strength can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the elapsed time after an aluminum component to be brazed and joined into a heating furnace and the temperature in the heating furnace.

FIG. 2 is a bar graph showing a relationship between a heating rate and an adhesion rate.

FIG. 3 is a perspective view showing a laminated evaporator, which is an example of a laminated heat exchanger produced by the brazing method of the present invention.

FIG. 4 is a partially exploded perspective view of the evaporator.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1a Projection part 1b Projection part 2 Plate material 3 Concave part 4 Projection 5a Joint part 5b Joint part 6 Element 7 First tank 8 Second tank 9 Connection hole 10 Seat plate 11 Tank body 12 Fin 13 Partition wall 14 Entrance chamber 15 Exit chamber 16 Refrigerant inlet 17 Refrigerant outlet

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-14395 (JP, A) JP-A-3-52762 (JP, A) JP-A-1-143794 (JP, A) JP-A-1- 143796 (JP, A) JP-A-61-49995 (JP, A) JP-A-59-54496 (JP, A) JP-B-58-27037 (JP, B2) (58) Fields investigated (Int. ⁷ , DB name) B23K 1/00-3/08

Claims (1)

(57) [Claims] 1. A fluoride-based flux using polybutene as a dispersion medium is applied to a surface of at least one of a plurality of aluminum parts, which are brazed and joined to each other, After combining the plurality of aluminum parts with the brazing filler metal interposed between the contact surfaces, the plurality of aluminum parts are placed in a heating furnace having a non-oxidizing atmosphere inside. A method for brazing aluminum parts by heating to melt the brazing material and brazing the plurality of aluminum parts together, wherein at least the sublimation temperature of polybutene is higher than that of the fluoride-based flux. Characterized in that the heating rate in the heating furnace until the temperature reaches a temperature lower than the temperature at which the aluminum becomes active is regulated to 19 to 25 ° C./min. Method for brazing rubber parts.