JP6255193B2 - Heat transfer brazing method - Google Patents

Description

  The present invention relates to a heat transfer brazing method and a related technique in which a heated mold is brought into contact with a member to be joined having a brazing material interposed at a bonding interface to heat a bonded portion.

  Various methods of brazing aluminum are classified according to the presence / absence of use of a flux, a heating method, a heating atmosphere, and the like (see Non-Patent Document 1).

  Further, as a method for brazing a lap joint, a heat transfer brazing method is known in which a brazing material is interposed between members to be joined, and a heated mold is brought into contact with the brazed material to heat the joint. The heat transfer brazing method is a heating method that uses heat conduction by contact, so it has the advantage that the joint is heated rapidly and can be brazed in a short time, such as resistance spot welding, torch brazing, high frequency brazing. It attracts attention as a brazing method that replaces the law (see Patent Document 1).

  For heat transfer brazing, a heating die corresponding to the shape of the member to be joined and the brazing area is used. For example, the heating die described in the drawing of Patent Document 1 is for partial joining instead of spot welding, and the area of the heat transfer surface to the member to be joined is small. Also, the brazing of the heat exchanger having the inner fins is the joining of the aluminum plate that becomes the outer shell of the refrigerant chamber and the corrugated fins, so that a heating mold having a heat transfer surface equivalent to the area of the aluminum plate is used. Use.

Japanese Patent Laid-Open No. 7-9124

Hiroshi Kawase, brazing of aluminum, light metal, August 1986, pages 514-524

  In heat transfer brazing, in order to obtain high heat transfer efficiency, it is desirable that the heating die and the member to be joined are in contact with each other without any gap, and the heat transfer surface of the die is required to be smooth. However, it is unavoidable that the smoothness of the heat transfer surface is impaired due to thermal deformation or wear due to repeated use of the mold. If a slight gap is formed between the heat transfer surface of the mold and the member to be joined, heat conduction is hindered and brazing takes time. Maintenance for restoring smoothness by polishing or the like is performed on the molds used repeatedly.

  In particular, in a mold having a large heat transfer surface area used for brazing of the heat exchanger, the effect of a decrease in heat transfer due to the gap is great, and maintenance for recovering smoothness is troublesome.

  In view of the above-described technical background, the present invention provides a heat transfer brazing method and related technology capable of realizing rapid heating without reducing the heat transfer efficiency even when a mold having a reduced heat transfer surface smoothness is used. To do.

  That is, this invention has the structure as described in following [1]-[7].

  [1] The heat transfer surface of the heating mold is brought into contact with the temporary assembly assembled by interposing the brazing material at the bonding interface of the members to be bonded, and gas is ejected from the opening provided in the heat transfer surface. A heat transfer brazing method comprising melting a brazing material and brazing a member to be joined.

  [2] The heat transfer brazing method according to item 1, wherein the opening is provided near the periphery of the heat transfer surface.

  [3] The heat transfer brazing method according to item 1 or 2, wherein the gas is an inert gas.

  [4] The heat transfer brazing method according to any one of items 1 to 3, wherein the gas is a heated gas.

  [5] The heat transfer brazing method according to any one of items 1 to 4, wherein the gas has a flow velocity of 5 m / sec or less.

  [6] The heat transfer brazing method according to any one of the above items 1 to 5, wherein the temporary assembly is a heat exchanger that brazes fins between two members arranged to face each other.

  [7] A heat transfer brazing method characterized in that an opening for ejecting gas is provided on a heat transfer surface to be brought into contact with a temporary assembly assembled by interposing a brazing material at a bonding interface of a member to be bonded. Mold for heating.

  According to the heat transfer brazing method described in [1], the heat transfer surface of the heating mold is ejected in the gap formed between the surface of the temporary assembly and the heat transfer surface of the heating mold. Gas causes forced convection to improve heat transfer efficiency. For this reason, even when using a heating mold with reduced smoothness of the heat transfer surface, the temporary assembly can be rapidly heated to achieve good brazing in a short time. Further, it is possible to reduce the number of times of maintenance for restoring the smoothness by polishing the heat transfer surface whose smoothness has been lowered by repeated use.

  According to the invention described in [2], heat transfer efficiency can be improved by jetting gas to the peripheral portion of the heat transfer surface where a gap is likely to occur.

  According to the invention described in [3], it is possible to achieve good brazing by preventing oxidation of the joint.

  According to the invention described in [4], the effect of improving the heat transfer efficiency can be enhanced without being influenced by the shape of the mold, the position or type of the heater, or the like.

  According to the invention described in [5], forced convection can be sufficiently generated in the gap.

  According to invention of [6], the said effect can be show | played in the brazing of the heat exchanger which brazes a fin.

  According to the heat transfer brazing heating die described in [7], gas is ejected from the opening of the heat transfer surface of the heating die so that the surface of the temporary assembly and the heating die are Heat transfer efficiency can be improved by causing forced convection in a gap formed between the heat transfer surface and the heat transfer surface. For this reason, even when using a heating mold with reduced smoothness of the heat transfer surface, the temporary assembly can be rapidly heated to achieve good brazing in a short time. Further, it is possible to reduce the number of times of maintenance for restoring the smoothness by polishing the heat transfer surface whose smoothness has been lowered by repeated use.

It is sectional drawing which shows an example of the heat-transfer brazing method of this invention. It is a top view of the metal mold | die for heating of this invention. It is the elements on larger scale of FIG. It is sectional drawing which shows the heat-transfer brazing method of a heat exchanger.

  1 to 3 are sectional views schematically showing the heat transfer brazing method of the present invention.

  The temporary assembly (1) for brazing includes a corrugated fin (13) sandwiched between a lower plate (11) and an upper plate (12). The lower plate (11) and the upper plate (12) are aluminum bare materials, and the fin (13) is a double-sided brazing sheet in which a brazing material is clad on both sides of a core material. The joint portions (14) and (15) in the temporary assembly (1) are a contact portion between the lower plate (11) and the lower end portion of the fin (13), and an upper end portion of the upper plate (12) and the fin (13). Are in contact with each other, and each has a line shape.

  In addition, this invention does not limit the supply method of a brazing material to a brazing sheet. Other brazing material supply methods include spraying brazing material foil and powder brazing material. Further, in the illustrated example of the temporary assembly (1), the lower plate (11) and the upper plate (12) may be made of a brazing sheet, and the fin (13) may be made of a bare material.

  Although the said joining plan part (14) (15) is a line shape, since a fin (13) is a waveform and has many upper end parts and lower end parts, a lower board (11) and an upper board (12) A plurality of planned joining portions (14) and (15) are present at predetermined intervals over the entire surface of the fin side. In the heat transfer brazing of such a temporary assembly (1), the entire surfaces of the lower plate (11) and the upper plate (12) are heated.

  As shown in FIGS. 1 and 2, the heating mold (20) is composed of a lower mold (21) and an upper mold (22) made of thick plates, and the dimensions of the heat transfer surfaces (23) and (24). Corresponds to the dimensions of the lower plate (11) and the upper plate (12). The lower mold (21) and the upper mold (22) are heated by being thermally coupled to respective heaters (not shown). On the heat transfer surfaces (23) and (24) of the lower mold (21) and the upper mold (22), there are five pieces penetrating in the thickness direction of the mold and opening to the heat transfer surfaces (23) and (24). Circular holes (25a) and (25b) are provided near the center and the four corners. The circular holes (25a) and (25b) are connected to a gas supply unit (not shown) through pipes, and the gas supply unit switches between gas supply and stop, and adjusts the gas flow rate.

  The lower mold (21) and the upper mold (22) are arranged in such a manner that the temporary assembly (1) is sandwiched in the vertical direction, and further pressed so that the heat transfer surfaces (23) and (24) are placed on the upper plate (11). And adhere to the surface of the lower plate (12). At this time, if the smoothness of the heat transfer surfaces (23) and (24) is lowered, as shown in FIG. 3, the heat transfer surfaces (23) and (24) are moved to the lower plate (11) and the upper plate (11). 12) There is a part that does not come into contact, and the slight gap (30) created between them prevents the transmission from the lower mold (21) and upper mold (22) to the lower plate (11) and upper plate (12). Hinder.

  In the present invention, the gas (G) is ejected from the heat transfer surfaces (23) and (24) through the circular holes (25a) and (25b), and the gas (G) is caused to flow through the gap (30). ) And the heat transfer surfaces (23) and (24) of the upper plate (12) are urged to be heated. The gas (G) supplied from the gas supply unit is heated while passing through the circular holes (25a) and (25b) of the lower mold (21) and the upper mold (22), and after the ejection, the heat transfer surface (23) Since the heat from (24) is received, the heated gas (G) flows through the gap (30), and this heated gas (G) passes through the lower plate (11) and the upper plate (12). Heat. Since the brazing atmosphere gas exists in the gap (30), the atmosphere gas is heated on the heat transfer surfaces (23) and (24) without causing the gas (G) to be ejected, so that natural convection occurs. Although the lower plate (11) and the upper plate (12) are heated, the heat transfer efficiency can be increased by jetting the gas (G) to cause forced convection.

  3 shows a gap (30) between the heat transfer surface (24) of the upper mold (22) of the temporary assembly (1) and the upper plate (12) of the temporary assembly (1) and gas (G ), The gap between the lower plate (11) and the heat transfer surface (23) of the lower mold (21) and the gas ejection are the same.

  The heating mold (20) is a tool used repeatedly, and heating to brazing temperature and cooling to room temperature are repeated. Since the heating mold (20) is repeatedly raised and lowered in temperature and contacted with the temporary assembly (1) is repeated, the heat transfer surface (23) is slightly affected by thermal deformation and wear. It is unavoidable that the smoothness of (24) decreases. According to the heat transfer brazing method of the present invention, when such a heating mold (20) with reduced smoothness is used, the gas (G) is ejected from the heat transfer surface (23) (24). As a result, a decrease in heat transfer efficiency due to a decrease in smoothness can be compensated. In addition, the heating mold (20) with reduced smoothness of the heat transfer surfaces (23) and (24) can be restored to smoothness by maintenance such as polishing. However, the heat transfer efficiency is improved by jetting gas (G). The number of maintenance can be reduced by compensating for the decrease in

  The type of the gas (G) is not limited, but it is preferable to use an inert gas such as nitrogen gas or argon gas in order to suppress the oxidation of the joint and achieve good brazing. It is also preferable to place the temporary assembly (1) and the heating mold (20) in an inert gas atmosphere and perform heat transfer brazing in the inert gas atmosphere.

  In addition, the gas (G) is naturally heated by being ejected from the heat transfer surface (23) (24) of the heating mold (20) even when normal temperature gas is supplied, but in order to increase the heat transfer efficiency. It is preferable that the temperature of the gas (G) reaches the brazing temperature or is close to the brazing temperature. Examples of a method of increasing the temperature of the gas (G) to be ejected include a method of setting a gas supply path that makes the contact time with the mold (20) longer, or a method of setting a gas supply path that passes near the heater. . Further, a preheated gas may be supplied. If a preheated gas is used, the gas temperature can be controlled without being influenced by the shape of the mold, the position and type of the heater, and the like.

  The flow rate of the gas ejected from the heat transfer surfaces (23) and (24) is preferably 5 m / sec or less. In order to cause forced convection in the gap (30), it is sufficient to eject gas at a flow rate of 5 m / sec, and 5 m / sec or less is preferable because a large flow rate is not necessary because the gap is small. A particularly preferred flow rate is 0.5 to 3 m / sec.

  In the heat transfer surfaces (23) and (24), the number and position of the openings (25a) and (25b) through which the gas is ejected are not limited, but are preferably provided in a portion where a gap is easily generated. As shown in FIG. 3, the heating mold (20) is often deformed so that the peripheral edge is warped by repeated use, so that the opening is in the vicinity of the peripheral edge of the heat transfer surface (23) (24). It is preferable to provide it. In the case of the rectangular heat transfer surface (23) (24), the distance (d) from the periphery of the heat transfer surface (23) (24) to the opening (25b) is 5 to 20 of the length of the diagonal line (D). It is preferable to provide in the position which becomes%. The heating mold (20) shown in FIGS. 1 and 2 is an example in which an opening (25b) is provided at a distance (d) on a diagonal line (D) from a corner. In addition to the opening (25b) in the vicinity of the periphery, it is preferable to provide the opening (25a) in the center.

  Further, the shape and dimensions of the openings (25a) and (25b) are not limited, but it is sufficient that gas flows, and therefore, the equivalent circle diameter is preferably 5 mm or less.

  The heat transfer brazing method of the present invention is not limited to the case where the heating mold is brought into contact with two opposing surfaces of the temporary assembly. The number and contact position of the heating mold can be arbitrarily set in accordance with the position and shape of the planned joining portion. In addition, in the heat transfer brazing using a plurality of heating molds, brazing for ejecting gas from the heat transfer surface of at least one mold is included in the present invention.

  The heat transfer brazing method of the present invention uses a heating die having a large heat transfer area, such as a brazed product having a large joint area or a brazed product in which a plurality of joints are dispersed in a wide area. Suitable for For example, it is suitable for brazing of a heat exchanger for brazing fins. As in the temporary assembly of FIG. 1, there are various types of heat exchangers for brazing the flat plate and the corrugated fins. The heat exchanger (40) shown in FIG. 4 has a corrugated fin (45) sandwiched between a lower plate (41) serving as a bottom plate and an upper plate (42) having a bulging portion (43) in the center. As a result, the fin (45) is loaded inside the refrigerant chamber (44) formed between the lower plate (41) and the upper plate (42). The heat exchanger (40) brazes the peripheral edge (46) of the lower plate (41) and the upper plate (43), and the upper end and lower end of the fin (45) are connected to the inner surface of the refrigerant chamber (44). It is made by brazing. The heat exchanger brazing of the heat exchanger (40) is performed on the entire surface of the lower plate (41) and the bulging portion (43) of the upper plate (42) on the heat transfer surface of the heating dies (51) (52) ( 53) and (54) are brought into contact with each other, and gas is ejected through holes (55) opened in these heat transfer surfaces (53) and (54).

  The temporary assembly (1) was brazed using the heating mold (20) shown in FIGS.

The lower plate (11) and the upper plate (12) constituting the temporary assembly (1) are made of JIS 3003 and are aluminum flat plates of 3000 mm × 100 mm × thickness 5 mm. The fin (13) is a brazing sheet formed into a waveform of 300 mm × 100 mm × height 30 mm. The brazing sheet is a double-sided brazing sheet having a thickness of 0.5 mm and a clad rate of 5% on each side, in which both sides of a core material made of JIS 3003 are clad with a brazing material made of JIS 4045. A temporary flux (1) is obtained by adhering a fluoride flux of 10 g / m ^{2 on} both sides of the fin (13) and sandwiching the fin (13) between the lower plate (11) and the upper plate (12). Assembled.

  In the heating mold (20), the lower mold (21) and the upper mold (22) have the same shape, and are thick plates of 300 mm × 100 mm × thickness 50 mm. These lower mold (21) and upper mold (22) have five circular holes (25a) (25b) having a diameter of 2 mm that penetrate through the mold in the thickness direction and open to the heat transfer surfaces (23) and (24). ) Is drilled. Regarding the positions of the five circular holes, one (25a) is the center of the heat transfer surface (23) (24), and four (25b) are on the diagonal line (D), and the distance (d ) Is 25 mm. The circular holes (25a) and (25b) are connected to a gas supply pipe on the surface opposite to the heat transfer surfaces (23) and (24), and are supplied from a gas supply unit (not shown) as needed. Gas is ejected from the heat transfer surface (23) (24). Since the pipe is routed through the atmosphere heated by the lower mold (21) and the upper mold (22), the heated gas (G) is ejected from the heat transfer surfaces (23) and (24). To do.

  The reference example, comparative example, and example use a heating mold (20) with different smoothness of the heat transfer surface (23) (24), and braze the temporary assembly (1) having the same surface condition. did. The heat transfer surfaces (23) and (24) of the heating mold (20) used in the reference example are sufficiently polished and highly smooth. On the other hand, the heating molds used in the comparative examples and the examples were repeatedly used, and the smoothness of the heat transfer surfaces (23) and (24) was lowered.

  When the temporary assembly (1) is sandwiched between the lower mold (21) and the upper mold (22) of each example and further pressurized with a weight of 10 kg, the surface of the temporary assembly (1) in each example The height (h) of the gap (30) generated between the heat transfer surfaces (23) and (24) was as shown in Table 1. In addition, 0.1 mm of the clearance (h) of the reference example is a clearance inevitably generated by the assembly of the temporary assembly (1) and the heating mold (20).

  In each case, the lower mold (21) and the upper mold (22) are held at 610 ° C. so that the actual temperature of the temporary assembly (1) is 600 ° C. in each example, oxygen concentration: 5 ppm, dew point The reaction was performed in nitrogen gas at −65 ° C. In this brazing, the reference example and the comparative example were brazed without jetting nitrogen gas (G), and in the example, nitrogen gas (G) was jetted at a flow rate of 1 m / s. Table 1 shows the time required from the start of brazing for bringing the heating mold (20) heated to a constant temperature into contact with the temporary assembly (1) until satisfactory brazing was achieved.

  As shown in Table 1, even with the mold having a reduced smoothness of the example, by blowing nitrogen gas, good brazing can be achieved in the same time as the mold with a smoothness of the reference example. It was. Moreover, since the comparative example in which the clearance gap equivalent to the Example formed the brazing time longer than the Example, the improvement effect of the heat transfer efficiency by gas ejection was able to be confirmed.

  INDUSTRIAL APPLICABILITY The present invention is suitable for manufacturing a heat transfer brazing product using a heating mold having a large bonding area and a large heat transfer surface area, and can be suitably used particularly for brazing of a heat exchanger.

1 ... Temporary assembly
11 ... Lower plate (joined member)
12 ... Upper plate (members to be joined)
13 ... Fin (member to be joined)
20 ... heating mold
21 ... Lower mold
22… Upper mold
23, 24 ... Heating surface
25a, 25b ... Circular holes (openings)
30 ... Gap

Claims (8)

The heat transfer surface of the heating mold heated by being thermally coupled to the heater is brought into contact with the temporary assembly assembled by interposing the brazing material at the bonding interface of the members to be bonded, and the heat transfer surface The brazing material is melted to braze the member to be joined by jetting gas from the opening provided at a position in contact with the temporary assembly to the gap formed between the surface and the surface of the temporary assembly. Heat transfer brazing method.   The heat transfer brazing method according to claim 1, wherein the opening is provided near the periphery of the heat transfer surface.   The heat transfer brazing method according to claim 1, wherein the gas is an inert gas.   The heat transfer brazing method according to claim 1, wherein the gas is a heated gas.   The heat transfer brazing method according to claim 1, wherein a flow rate of the gas is 5 m / sec or less.   The heat transfer brazing method according to claim 1, wherein the temporary assembly is a heat exchanger that brazes fins between two members arranged to face each other.   The heat transfer brazing method according to any one of claims 1 to 5, wherein the temporary assembly is a heat exchanger that brazes a flat plate and a corrugated fin. This is a heating mold that is heated by being thermally coupled to the heater, and is in contact with the temporary assembly of the heat transfer surface that is brought into contact with the temporary assembly assembled by interposing the brazing material at the joining interface of the members to be joined. A heating mold for heat transfer brazing, wherein an opening for ejecting gas is provided in a gap formed between the surface and the surface of the temporary assembly .

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