JPS631152B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a brazing material in which the surface of an aluminum extrusion is coated with a brazing alloy. Today, aluminum is used for various industrial equipment, radiators, heat exchangers, etc. of vehicles, etc., taking advantage of aluminum's advantages such as lightness, workability, and good thermal conductivity, and in conjunction with the recent development of brazing technology. has been done. For example, heat sinks used in electronic devices are made by brazing extruded materials of various shapes and thickness onto a substrate, and radiators used in vehicles are made by brazing flat tubes and fins coated with a brazing alloy. It is then shaped into the desired shape and used. On the other hand, as a manufacturing method for this type of brazing material, there is a rolling joining method in which a pre-manufactured brazing alloy plate is clad and rolled onto the surface of an aluminum or aluminum alloy (hereinafter simply referred to as aluminum) plate serving as a core material, and this clad plate is A method of manufacturing a clad pipe by rounding it into a desired shape and then continuously seaming it, a clad extrusion method of cladding and extruding a brazing alloy material and aluminum as a core material, and adding a core material to a molten brazing alloy material. There are dipping methods in which aluminum is immersed, and a brazing material coated with a brazing alloy can be produced by any of these methods. but,
In the case of the rolling joining method, the surfaces of the plates to be joined must be cleaned to remove oxides, etc., which requires complicated pretreatment and equipment, and it is also difficult to manufacture pipes using these clad plates. In this case, it is difficult to obtain the desired uniform thickness of the brazing alloy layer at the seam joint. On the other hand, the clad extrusion method requires a clad double billet, and in addition, it is difficult to maintain and control the uniformity of the thickness of the braze alloy layer over the entire length of the extruded material.
Combinations of alloys, such as brazing alloys with low melting points and aluminum with high melting points, cannot be extruded. Furthermore, the dipping method has problems such as geometrical restrictions and difficulty in maintaining and controlling the thickness and uniformity of the braze alloy layer. The present invention was developed based on the above-mentioned circumstances, and by combining a thermal spraying process with a normal extrusion process, it is possible to continuously and uniformly coat the outer surface of aluminum extrusions of various shapes. It was confirmed that a strong Narou alloy layer could be formed. To further explain the method of the present invention as described above, the surface of warm extruded or hot extruded aluminum extruded material is a clean and active surface with no oxide film formed immediately after extrusion, so it cannot be thermally sprayed. It is thought that after the taro alloy is mechanically attached to the substrate, it immediately fuses to the wettable high-temperature surface, and a portion of it also diffuses onto the surface, resulting in a strong adhesion. In an embodiment of the method of the present invention, one or more automatic thermal spraying devices are installed near the die exit end of the extruder in order to uniformly coat a predetermined surface or the entire surface of the extruded material. As an example of installing the device, as shown in the side view of the device in FIG. 1, and the front view from the direction of progress of the extruded material in FIGS. If necessary, a thermal spray gun 4 is placed from the middle of the roller 3 for conveying the extruded material so as to perform thermal spraying perpendicular to the surface of the extruded material, thereby making the thermal spray coating layer uniform. The placement of the spray gun depends on the shape of the extruded material,
One or more units may be appropriately arranged depending on the purpose. For example, in the case of an extruded mold material for a heat sink, in order to strengthen the brazing between the base and the mold material during extrusion, an A-Si type brazing alloy or a low melting point brazing alloy is sprayed onto the brazing area. Form a coating layer of wax alloy. Particularly in the case of parts such as heat exchangers that do not like pit corrosion, such as flat tubes that serve as refrigerant passages, a solder alloy containing Zn is used during extrusion, for example, an A-Si-Zn-based solder. It is particularly effective to thermally spray the alloy,
In the subsequent brazing step, a Zn diffusion layer can be formed on the surface of the flat tube, and pit corrosion can be appropriately prevented. According to the method of the present invention, excellent film adhesion can be obtained without the need for plasting and preheating that are normally required for thermal spraying, and the process is also simplified.
In addition, when spraying brazing alloys, the particles are easily oxidized, so to prevent this, the flame should be made as reducing as possible, and if necessary, an inert gas should be used.
Further, general considerations such as making the spraying distance as short as possible are required, and the spraying process may be performed under an inert atmosphere. Further, by controlling the extrusion speed of the extruded material and the thermal spraying conditions, it is possible to arbitrarily control the thickness of the cladding layer. According to the method of the present invention, a uniform and highly adhesive cladding layer is continuously formed on the outer surface of various shapes. The apparatus is simple, and it can be said that the method for producing cladding materials is inexpensive and has excellent practicality. Specific examples of the method according to the present invention will be described below. Example 1 As shown in Figures 1 and 2, one automatic thermal spraying equipment was installed near the die end of the extruder, and aluminum continuous casting billet 148 having the composition shown in Table 1 was prepared.
mm x 500 x mm, a comb-shaped heat sink with a cross-sectional shape of 50 mm in width, 30 mm in height, and 7 comb teeth as shown in Fig. 2 was extruded at an extrusion speed of about 18 m/min. Under the thermal spraying conditions shown in Table 2, a brazing alloy wire having the composition shown in Table 1 was continuously thermally sprayed onto the portion to be attached to the substrate.

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[Table] As a result, a brazing alloy coating layer of 100 g/m ² was formed on the surface of the extruded material. The comb-shaped material thus formed and a substrate (not shown) were combined and brazed under the conditions shown in Table 3 below to produce a brazed product of a heat sink.

[Table] Good soldered joints were formed with an adhesion rate of 95% or higher, and sufficient brazing properties were obtained, indicating that this method is extremely effective for brazing aluminum. Example 2 As in Example 1, four automatic thermal spraying equipment were installed near the die end of the extruder as shown in Figure 3, and a billet having the composition shown in Table 4 and the dimensions shown in Example 1 was produced. A flat tube with a cross-sectional shape shown in Fig. 4, width 26 mm, height 5 mm, tube thickness 0.8 mm, and partition wall thickness 1.0 mm having four refrigerant channels was extruded at an extrusion speed of approximately 15 m/min. Thermal spraying was continuously carried out over the entire surface under the spraying conditions shown in Table 2 using a Zn-containing brazing alloy wire having the composition shown in Table 4.

[Table] As a result, a brazing alloy coating layer of approximately 30 μm was formed on the surface of the extruded material. Extruded flat tube formed in this way and A300 ₃
In combination with corrugated fins made of wood,
Brazing was performed under the conditions shown in Table 3 to produce laminated brazed products. As a result of being maintained at the brazing temperature, it was confirmed by an X-ray microanalyzer that a diffusion layer with a Zn concentration of 1.0% by weight and a Zn diffusion layer depth of 80 μm was formed on the surface of the extruded flat tube. This brazed item is JIS H
As a result of conducting the CASS test specified in 8661 for 720 hours, all the corrosion that occurred was in the form of surface corrosion, no pitting corrosion was observed, and a uniform and adherent Zn-containing brazing alloy coating layer was formed. It has been shown.

[Brief explanation of the drawing]

FIG. 1 is a side view of an embodiment of the method of the invention;
3 and 3 are front views from the direction in which the extruded material advances, showing examples of the arrangement of thermal spray guns, and FIG. 4 is an enlarged sectional view of the extruded flat tube. 1 is an extruder, 2 is an extruded material, 3 is a conveying roller,
4 is a thermal spray gun.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a brazing material, characterized in that a coating layer of a brazing alloy is formed by spraying a brazing alloy onto the surface of an extruded aluminum material near an extrusion port of an extrusion molding machine. 2. The method for producing a brazing material according to claim 1, wherein the brazing alloy contains zinc.