JP2012096264A - Aluminum alloy preplaced brazing and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, when brazing is performed, the kind and using method of a brazing filler metal are restricted by shape, clearance, the use-nonuse of flux, a brazing system or the like, and working efficiency is inferior; and further, to solve the problem that, when brazing heating is performed by using flux, a step is also needed of removing the residue of the flux remaining in a part with complicated shape, and that productivity is deteriorated.SOLUTION: Brazing is performed without using flux by using an aluminum alloy brazing filler metal wire obtained by disposing the outside of an aluminum alloy brazing filler metal containing, by mass, 5 to 13% Si and 0.1 to 5% Mg, and the balance Al with inevitable impurities with a skin material composed of an aluminum material having a solidus temperature higher than the liquidus temperature of the brazing filler metal.

Description

  The present invention provides an aluminum alloy brazing wire, a method for producing the aluminum alloy brazing wire, and a method for producing a heat exchanger in an attempt to place the aluminum alloy brazing wire, particularly using a flux in an inert gas atmosphere. The present invention relates to a technique for manufacturing a heat exchanger by brazing and heating.

  For example, as shown in FIG. 1, a heat exchanger such as a radiator is a fin 2 (corrugated fin) formed by bending a flat tube 1 extruded into a tube in a hot or warm manner in a meandering manner and forming a brazing sheet between the tubes. Is attached. The fin material has JIS 3003 or an alloy containing Zn or the like for the purpose of giving a sacrificial effect as a core material, and both sides of a brazing material such as JIS 4045 (Al-10mss% Si) and JIS4343 (Al-7.5mass% Si). Is clad.

  The heat exchanger is integrated and assembled by brazing and heating the flat tube with the fins attached thereto, so that the brazing material on the surface of the fin material melts and fills the gaps between the members. Examples of the brazing heating method include a flux brazing method using a flux and a nocolok brazing method using a non-corrosive flux.

  By the way, as problems that occur during brazing heating, there are crushed fins, erosion of brazing material to tubes and the like, and brazing where brazing is not sufficiently supplied to the joint. In order to cope with these, brazing heating is performed while finely adjusting the heating rate. In addition, since the melting point of aluminum is about 660 ° C., if the brazing temperature is increased as much as possible, erosion occurs in which the brazing material diffuses into the base metal, and therefore the upper limit of the brazing temperature is strictly controlled. The additional heating is performed at a temperature around 600 ° C.

  However, in practice, it is not easy to uniformly heat the entire heat exchanger due to the difference in temperature distribution in the furnace and the heat capacity of the members. If the brazing temperature is set so that erosion does not occur at the place where the temperature is highest among the heat exchanger parts, the temperature does not rise to the brazing temperature depending on the part of the heat exchanger, and brazing occurs. Brazing is an important manufacturing defect because the heat transfer characteristics of the heat exchanger are extremely reduced.

In particular, since the connector part between the heat exchanger and the pipe part is a part where a thin plate member or a thick plate member is in contact, a temperature difference is likely to occur between the members, and a brazing failure is likely to occur. In order to braze such a part at the same time as the heat exchanger, the brazing material is processed into a linear shape, a ring shape, a spring shape, and a washer shape according to the shape of the joint portion, and is used for placing.
Japanese Patent Application No. 2006-150442 Japanese Patent Application No. 9-047892

  However, the type of brazing material and the method of use are restricted by the connector shape, the clearance of the piping, and the use / non-use of the flux, the brazing method, etc., and there is a problem that the work efficiency is poor. Further, when brazing heating is performed using a flux, a step of removing the flux residue remaining in the complicated shape portion such as the connector portion is necessary, which causes a problem that productivity is lowered.

  The present inventors have intensively studied to solve the above problems, and found that productivity can be remarkably improved by trying to place a low melting point brazing alloy and brazing without using a flux.

  That is, the first invention according to claim 1 is the liquidus line of the brazing material outside the aluminum alloy brazing material containing Si 5-13 mass%, Mg0.1-5 mass%, the balance Al and unavoidable impurities. An aluminum alloy brazing wire characterized by providing a skin material made of an aluminum material having a solidus temperature higher than the temperature.

  A second invention according to claim 2 is an aluminum alloy brazing wire characterized in that the skin material according to claim 1 is pure Al or an Al-Mn alloy.

  A third invention according to claim 3 includes Si 5 to 13 mass%, Mg 0.1 to 5 mass%, and is higher than the liquidus temperature of the billet on the outer peripheral portion of the aluminum alloy billet composed of the balance Al and inevitable impurities. A method for producing an aluminum alloy brazing wire characterized by drawing a wire after fitting a pipe made of an aluminum material having a solidus temperature.

  A fourth invention according to claim 4 is the method for producing an aluminum alloy brazing wire characterized in that the pipe according to claim 3 is pure Al or an Al-Mn alloy.

  According to a fifth aspect of the present invention, in manufacturing an aluminum alloy heat exchanger, the aluminum alloy brazing wire is left as a wire, or is processed into a spring shape or a ring shape so as to be brazed. It is the manufacturing method of the aluminum-alloy heat exchanger characterized by arrange | positioning and brazing and heating, without using a flux in inert gas atmosphere.

  As described above, the use of the aluminum alloy brazing wire of the present invention eliminates the need for expensive equipment such as a vacuum furnace and a highly airtight atmosphere furnace, and also eliminates the need for flux, and the process of removing the residue after flux coating and brazing. Is also unnecessary, improving productivity and reducing costs. In addition, it is possible to perform brazing with excellent workability by simply sandwiching a ring in which a wire is processed during brazing assembly.

It is a perspective view which shows a serpentine type evaporator.

  First, the reason for limiting the brazing filler metal component will be described.

  Si is an indispensable alloying element for the aluminum alloy brazing material, and has an effect of lowering the melting point of the brazing material and improving the flowability of the molten brazing material. However, if the amount is less than 5 mass% or more than 15 mass%, the melting point is not sufficiently lowered, the flowability of the molten wax is poor, and the brazing occurs at the low temperature portion. Moreover, when it exceeds 15 mass%, Si crystallized substance will be produced | generated, the supply of the wax to a fillet part will decrease, and the erosion of a core material will become large. Therefore, the Si amount is set to 5 to 15 mass%. A more preferable amount of Si is 9 to 12 mass%.

  Mg diffuses from the inside of the material to the material surface during brazing heating, and promotes the wetting and spreading of the brazing by destroying and removing the oxide film formed on the surface. In particular, when the oxygen concentration in the inert gas atmosphere is high, the addition of Mg is effective because an oxide film is likely to be formed during brazing heating and the brazing property is hindered. If the added amount is less than 0.1 mass%, the effect of promoting the wetting and spreading of the wax is not obtained. If the added amount exceeds 5 mass%, the promoting effect is saturated, which is not economical. Therefore, the Mg amount is set to 0.1 to 5 mass%. A more preferable amount of Mg is 0.5 to 2 mass%.

  Bi has the effect of coexisting with Mg or promoting the wettability of wax in an inert gas atmosphere alone, and may be added in the range of 0.01 to 0.5 mass%.

  Furthermore, Zn, In, and Sn impart sacrificial anticorrosive action to the brazing material and improve the corrosion resistance of the core material. Therefore, Zn may be added in the range of 0.01 to 5 mass%, In may be added in the range of 0.01 to 0.1 mass%, and Sn may be added in the range of 0.01 to 0.1 mass%.

  Note that Fe is allowed because it does not adversely affect the properties of the brazing material even if it is contained up to about 0.5 mass% or less. Other inevitable impurities are each preferably 0.05 mass% or less, and the total is preferably 0.15 mass% or less.

  Next, the skin material will be described. As the aluminum alloy used for the skin material of the present invention, an aluminum alloy having a solidus temperature higher than the liquidus temperature of the brazing material is used. An aluminum alloy to be used may have any composition as long as this condition is satisfied. In consideration of necessary product strength, corrosion resistance, etc., JIS A 1070, 1050, 1100, 1200, 3003, 3203, 3004, 5005, 5N01, 6951, 6061, 6063 , 6N01, etc., or alloys obtained by adding various alloy elements to these alloys. However, if Mg is contained in the skin material, an oxide film on the surface of the skin material is likely to grow during the heating process of brazing heating. Therefore, the skin material does not contain Mg, and pure Al or Al-Mn having excellent ductility. Alloys are preferred.

  A method for producing the aluminum alloy brazing wire of the present invention will be described.

  A conventional aluminum alloy brazing wire has been obtained by forming a billet of about 10 mm by directly or indirectly extruding a DC-cast alloy billet, and further drawing it into a wire having a predetermined thickness. However, since the aluminum alloy brazing material contains a large amount of Si-based intermetallic compounds, cracks are often generated at the time of drawing, starting from these intermetallic compounds.

  The aluminum alloy brazing wire of the present invention chamfers the outer peripheral shape of a DC casting brazing alloy billet. On the other hand, a hollow pipe having the same inner diameter as the outer diameter of the brazing alloy alloy billet is manufactured with a pure Al alloy or Al-Mn alloy having high ductility. Then, the brazing material alloy billet is fitted into the hollow pipe and integrated. Thereafter, the integrated material is heated to 300 to 500 ° C., and then drawn to form a hollow pipe made of a brazing material and a pure Al alloy or an Al—Mn alloy (finally, a skin material. ) Can be completely adhered. The drawing process may be either extrusion, drawing, or a combination of these methods.Since the brittle brazing material is covered with a highly ductile skin material, it does not cause cracks in the internal brazing material and has a similar shape. Can be processed into a thin wire shape.

  The diameter of the aluminum alloy brazing wire of the present invention is 0.5 to 3.0 mm. When the diameter exceeds 3.0 mm, it becomes difficult to bend into a ring shape or the like. In terms of convenience in use, a diameter of 2.0 mm or less is particularly desirable. On the other hand, when the diameter is smaller than 0.5 mm, it is impossible to supply a brazing material sufficient to fill the joint. From a practical viewpoint, a diameter of about 0.5 mm is appropriate as the lower limit.

  The aluminum alloy brazing wire of the present invention can be brazed without a flux in brazing under a normal inert gas by arranging a skin material having a thickness of 1 to 450 μm on the wire surface. Here, it is difficult in manufacturing to make the thickness of the thin skin uniformly less than 1 μm. On the other hand, when the thickness of the thin skin is thicker than 450 μm, Mg contained in the brazing material becomes difficult to diffuse to the surface of the skin material during brazing, and the wettability of the wax in an inert gas atmosphere is deteriorated. Therefore, the thickness of the skin material is preferably 1 to 450 μm.

  Next, a method for producing an aluminum alloy heat exchanger or the like using the aluminum alloy brazing wire of the present invention will be described.

  When manufacturing a structure such as a heat exchanger, the aluminum alloy brazing wire according to the present invention is to be brazed after being processed into a predetermined shape or size such as a ring, spring, or washer. Used to place it on the site. Examples of the aluminum alloy heat exchanger include, but are not limited to, a radiator, a condenser, a heater, and an evaporator.

  The present invention will be specifically described below with reference to examples.

  The brazing material billet having the alloy composition shown in Table 1 was produced by DC casting, and the outer diameter was chamfered. Specimens obtained by fitting pipes made of pure Al alloy (JIS A 1050) to these billets were obtained. These specimens were heated to 400 ° C., and rods having a diameter of 50 mm were produced by an extrusion method. Next, these rods were drawn to produce a wire having a diameter of 0.4 to 5 mm.

  As a result, for the brazing alloy as an example of the present invention and the brazing alloy as a conventional example (JIS A 4045), a wire having a predetermined diameter could be manufactured, but the amount of Si was outside the scope of the present invention. Alloys No. 12 and 13 of comparative examples are inferior in brazeability, In the case of No. 13, wire breakage occurred frequently during drawing, and the wire could not be manufactured stably.

  The wire produced above was used to be placed on the brazed portion between the tube and connector of the heat exchanger of FIG. That is, at the time of assembly before brazing, a wire was placed in a ring shape around the connector inserted into the tube.

  At this time, for the brazing alloy as an example of the present invention and the brazing alloy as a conventional example (JIS A 4045), a ring having no surface defects such as cracks could be formed on the surface. Comparative Examples Nos. 12 and 13, particularly No. 1, which fall outside the scope of the present invention. It was found that No. 13 caused many cracks on the molded ring surface, and the function to place it could not shine.

  The assembled product was held for 3 minutes in a brazing furnace at 600 ° C. in an inert gas atmosphere without using flux. Ten heat exchangers were manufactured for each brazing alloy, and each heat exchanger was filled with He gas, and the occurrence of leakage failure at the brazed portion between the tube and the connector was examined. The results are also shown in Table 1.

  For the alloys (Nos. 1 to 11) of the examples of the present invention, there was no heat exchanger that caused a leakage failure. In contrast, the alloy composition range of the present invention example, the comparative example alloys (No. 12-18) out of the diameter and the conventional alloy (No. 19), there is a heat exchanger in which a leakage failure has occurred. there were.

1. Flat tube 2. Fin 3. connector

Claims (5)

  It is made of an aluminum material having a solidus temperature higher than the liquidus temperature of the brazing material on the outer side of the aluminum alloy brazing material containing 5 to 13 mass% of Si and 0.1 to 5 mass% of Mg and the balance Al and inevitable impurities. An aluminum alloy brazing wire characterized by a skin material.   An aluminum alloy brazing wire, wherein the skin material according to claim 1 is pure Al or an Al-Mn alloy.   A pipe made of an aluminum material having a solidus temperature higher than the liquidus temperature of the billet on the outer peripheral portion of an aluminum alloy billet containing Si 5-13 mass% and Mg 0.1-5 mass% and the balance Al and inevitable impurities A method for producing an aluminum alloy brazing wire characterized by drawing a wire after fitting.   The pipe according to claim 3 is pure Al or Al-Mn system alloy, The manufacturing method of the aluminum alloy brazing material wire characterized by things. When manufacturing an aluminum alloy heat exchanger, the aluminum alloy brazing wire is processed as a wire or a spring or ring and placed at the location to be brazed, and flux is applied in an inert gas atmosphere. A method for producing an aluminum alloy heat exchanger, characterized by brazing and heating without using.

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