JP6215025B2 - 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, one of the conditions for achieving good brazing is uniform heating of the joint, and the temperature of the heat transfer surface of the heating mold is required to be uniform.

  However, as shown in the isotherm diagram of FIG. 3, since the heating mold (50) is radiated from the peripheral end, the temperature of the heat transfer surface (51) is higher in the center and lower as it goes to the end. Become. Therefore, as shown in FIG. 4, in order to uniformly heat the joint portion of the temporary assembly (1), a mold (50) larger than the size (W × L) of the joint portion is used, It is necessary to assemble so that the temperature drop region at the peripheral edge of the heat transfer surface (51) is removed from the joint. In particular, in a mold having a large area of the heat transfer surface used for brazing the heat exchanger, the temperature difference tends to be large between the central portion and the peripheral portion of the heat transfer surface. In addition, when performing heat transfer brazing in a brazing furnace in an inert gas atmosphere, the dimensions of the brazing furnace must be increased with the expansion of the dimensions of the heating mold, resulting in an increase in equipment cost.

  In view of the technical background described above, the present invention heats a portion of the temporary assembly that comes into contact with the peripheral portion of the heat transfer surface, which is reduced by heat dissipation in heat transfer brazing, and substantially expands the preferred temperature range of the heat transfer surface. A method and related techniques are provided.

  That is, this invention has the structure as described in following [1]-[5].

  [1] A heating assembly of a heating mold is brought into contact with a temporary assembly assembled by interposing a brazing material at a joining interface of a member to be joined, and the heating mold is disposed in the vicinity of the peripheral end of the heating mold. A heat transfer brazing method characterized in that a heating gas introduced into a mold is circulated through a gas flow passage that opens on a side surface of the mold, and a brazing material is melted to braze the member to be joined.

  [2] The heat transfer brazing method according to item 1, wherein the heating gas is a gas having a temperature higher than the brazing temperature.

  [3] The transmission according to the above item 1 or 2, wherein the heating mold has a square shape in plan view, and the heating gas introduced in the vicinity of the corner of the heating mold is circulated through the gas flow passage leading to the corner. Thermal brazing method.

  [4] The heat transfer brazing method according to any one of the preceding items 1 to 3, wherein the temporary assembly is a heat exchanger that brazes fins between two members arranged to face each other.

  [5] A heating mold to be brought into contact with a temporary assembly assembled by interposing a brazing material at the joining interface of the members to be joined, the gas flow having a discharge port on the side surface in the vicinity of the peripheral end of the heating mold A heat transfer brazing heating mold characterized in that a path is provided.

  According to the heat transfer brazing method described in [1], the heating gas flowing through the gas flow passage heats the mold. The gas flow passage is provided in the vicinity of the peripheral edge of the mold so as to open to the side surface of the mold, and the position of the gas flow passage corresponds to a peripheral region where the heat transfer surface temperature is lowered by heat radiation. Therefore, the temperature decreasing region of the heat transfer surface is heated with the heating gas, and the temperature difference between the portion contacting the central portion of the heat transfer surface and the portion contacting the peripheral portion of the temporary assembly is reduced. The preferred temperature range for heat transfer brazing on the hot surface is substantially enlarged. And a metal mold | die can be reduced in size because the suitable temperature range of a heat-transfer surface is expanded. Also, the brazing furnace can be downsized by downsizing the mold.

  According to the heat transfer brazing method described in [2], since the temperature of the heating gas is higher than the brazing temperature, the substantial temperature of the temporary assembly can be reliably increased.

  According to the heat transfer brazing method described in [3], it is possible to expand the preferable temperature region by circulating the heating gas in the vicinity of the corner where the temperature tends to decrease particularly in the rectangular mold in plan view.

  According to the heat transfer brazing method described in [4], the above effect can be achieved in brazing of a heat exchanger for brazing fins.

  According to the heat transfer brazing mold described in [5], the mold can be heated by circulating the heating gas through the gas flow passage. The gas flow passage is provided with a discharge port on the side surface of the mold in the vicinity of the peripheral edge of the mold, and the position of the gas flow passage corresponds to the peripheral region where the heat transfer surface temperature is reduced by heat radiation. The temperature-lowering region can be heated. Therefore, the temperature difference between the portion that contacts the central portion of the heat transfer surface and the portion that contacts the peripheral portion of the joint portion of the temporary assembly is reduced, and a suitable temperature range for heat transfer brazing on the heat transfer surface is substantially reduced. Can be enlarged. And a metal mold | die can be reduced in size because the suitable temperature range of a heat-transfer surface is expanded. Also, the brazing furnace can be downsized by downsizing the mold.

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 a heating used by this invention. It is the 2B-2B sectional view taken on the line of FIG. 2A. It is an isotherm figure in the heat transfer surface of the conventional heating metal mold | die. It is sectional drawing which shows the heat-transfer brazing method using the conventional metal mold | die for a heating.

  FIG. 1 is a cross-sectional view schematically showing the heat transfer brazing method of the present invention.

  The temporary assembly (1) of the heat exchanger shown in FIG. 1 has a corrugated lower plate (11) serving as a bottom plate and an upper plate (12) having a bulging portion (13) in the center. The fin (15) is loaded inside the refrigerant chamber (14) formed between the lower plate (11) and the upper plate (12) by sandwiching the fin (15). The temporary assembly (1) brazes the peripheral portion (16) of the lower plate (11) and the upper plate (13), and the upper end and lower end of the fin (15) are connected to the refrigerant chamber (14). It is produced by brazing to the inner surface. In the temporary assembly (1), the method for supplying the brazing material is not limited. For example, the lower plate (11) and the upper plate (13) can be supplied to the joint portion by forming a brazing sheet in which a brazing material is clad in a core material. Further, the fin (15) may be composed of a brazing sheet on both sides.

  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.

  The joints of the fins (15) in the refrigerant chamber (14) are linear, but the fins (15) are corrugated and have a number of upper and lower ends, so that the lower plate (11) and the upper A plurality of joints exist at predetermined intervals over the entire surface of the fin side of the plate (13). In the heat transfer brazing of such a temporary assembly (1), the entire surfaces of the lower plate (11) and the upper plate (13) are heated.

  As shown in FIGS. 1 to 2B, the heating mold (2) is composed of a lower mold (20) and an upper mold (30) having the same shape made of a thick plate having a rectangular shape in plan view. It is heated by being thermally coupled to (omitted).

  As shown in FIGS. 2A and 2B, the lower mold (20) and the upper mold (30) have openings in the opposing surfaces (26) and (36) of the heat transfer surfaces (21) and (31) in the vicinity of the four corners. Bottomed circular holes (22), (32), and gas flow passages (24), (34) communicating with the bottoms of these circular holes (22), (32) and opening to the side of the mold Yes. The gas flow passages (24) and (34) extend substantially parallel to the heat transfer surfaces (21) and (31), and open at the corners of a rectangular mold in plan view, thereby providing gas discharge ports (25) and (35). Forming. The openings of the circular holes (22) and (32) form inlets (23) and (33) to the gas flow passages (24) and (34). Furthermore, the inlets (23) and (33) of the circular holes (22) and (32) are connected to a gas supply unit (not shown) via pipes, and the gas supply unit switches between gas supply and stop, Flow rate adjustment is performed.

  In the heat transfer brazing of the temporary assembly (1), the heat transfer surface (21) of the lower mold (20) is brought into contact with the lower plate (11) and the heat transfer surface of the upper mold (30) ( 31) is brought into contact with the bulging portion (13) of the upper plate (12), and the temporary assembly (1) is assembled so as to be sandwiched between the upper and lower molds.

  Although the heat transfer brazing mold is heated, since the heat is radiated from the peripheral portion, the temperature of the heat transfer surface is not uniform and the peripheral portion has a lower temperature than the central portion. FIG. 3 is an example of an isotherm diagram on the heat transfer surface (51) when a heater is connected to the center of the square mold (50). The temperature is higher at the center and lower at the end. Show. Since the heat transfer surface (51) in the illustrated example is rectangular, the temperature of the corner (52) is particularly low. In order to achieve good brazing using a mold having such a temperature distribution, avoid the temperature drop region (53) at the peripheral edge where the heat transfer surface temperature is lower than the predetermined temperature (55). Only the temperature zone (54) must be in contact with the joint of the temporary assembly (1). For this reason, a metal mold having a large size is used in anticipation of the temperature reduction region (53) of the heat transfer surface (51). For example, FIG. 4 shows the case where the upper and lower parts of the temporary assembly (1) in FIG. A large mold (50) having dimensions of the heat transfer surface (51) of about 1.2 W × 1.2 L is required. In addition, the larger the mold (50), the larger the brazing furnace.

  The present invention heats the mold by circulating the heating gas (G) in the mold (20) (30) in the portion corresponding to the temperature drop region of the heat transfer surface (21) (31) due to heat radiation. And uniformize the heat transfer surface temperature.

  As shown in FIG. 1, in the lower mold (20), when the heating gas (G) is supplied from the introduction port (23), the heating gas (G) flows through the circular hole (22) into the gas flow path (24). And is discharged from the gas outlet (25). While the heating gas (G) passes through the gas flow passage (24), the temperature decreasing region at the peripheral edge of the heat transfer surface (21) is heated to recover the lowered heat transfer surface temperature. Due to the above action, the temperature difference between the portion of the temporary assembly (1) on the lower plate (11) side that contacts the central portion of the heat transfer surface (21) and the portion that contacts the peripheral portion is reduced. The uneven heating due to the temperature difference of the hot surface (21) is eliminated and the heating is evenly performed. That is, the preferred temperature range for heat transfer brazing on the heat transfer surface (21) is substantially expanded. And a metal mold | die can be reduced in size because the suitable temperature range of a heat-transfer surface (21) is expanded. For example, if the region (joining part) that requires soaking in the lower plate (11) of the temporary assembly (1) is a square of W × L, 1.2 W × unless the heating gas (G) is circulated. Although a 1.2 L heat transfer surface (21) is required, the heat transfer surface (21) can be reduced to 1.1 W × 1.1 L by circulating a heating gas in the four corners. . Further, if the mold is downsized, the brazing furnace can be downsized.

  As for the upper mold (30), the heating gas (G) can be introduced in the same manner as the lower mold (20), but the upper plate (12) side joint is smaller than the lower plate (11) side. In this example, the heating gas (G) is not introduced because the portion is accommodated inside the gas flow passage (34). In the heat transfer brazing of the temporary assembly (1) in the example shown in the figure, the upper mold (30) can be reduced in size according to the dimensions of the joint on the upper plate (12) side, and narrowed due to the reduction in size. Like the lower mold (20), the preferred temperature range can be expanded by introducing a gas for heating (G) by providing a gas flow passage.

  In the present invention, the formation position of the gas flow passage is not limited to the corner. An arbitrary number of gas flow passages can be provided at a position where the temperature is likely to be lowered according to the planar shape of the heating mold, that is, the shape and dimensions of the heat transfer surface, so that the preferable temperature region of the heat transfer surface can be expanded. Since the temperature at the corner of the rectangular, particularly quadrangular heat transfer surface is likely to decrease, the preferred temperature region can be expanded by providing a gas flow passage at the corner to allow the heating gas to flow.

  Further, the position of the inlet for supplying the heating gas to the gas flow passage is not limited. However, if a hole is formed in the opposite surface of the heat transfer surface as shown in the drawing, the communication to the gas flow passage is possible. Such an embodiment is desirable. Further, the gas flow path is not limited to being parallel to the heat transfer surface, and may be a slant hole that opens to the side surface of the mold and the surface opposite to the heat transfer surface.

  The temperature of the heating gas (G) is not limited as long as the substantial temperature of the temporary assembly (1) can be raised. However, in order to reliably raise the (1) solid temperature of the temporary assembly to the brazing temperature, the temperature is preferably higher than the brazing temperature. Specifically, it is preferable to distribute a gas that is 5 to 30 ° C. higher than the brazing temperature. As a method of obtaining the heating gas (G), a method of setting a gas supply path that makes the contact time with the molds (20) and (30) longer, or a method of setting a gas supply path that passes near the heater is used. It can be illustrated. 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 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.

  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 according to the position and shape of the joint. Further, in the heat transfer brazing using a plurality of heating dies, brazing that causes the heating gas to flow through the gas flow passage leading to the discharge port on the side surface in the vicinity of the peripheral end of at least one die is included in the present invention. included.

  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 A heating mold having a large heat transfer area is likely to cause a temperature difference between the central portion and the peripheral portion, so that it is significant to apply the method of the present invention.

  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
2 ... heating mold
11 ... Lower plate (joined member)
12 ... Upper plate (members to be joined)
15 ... Fin (member to be joined)
20 ... Lower mold
30 ... Upper mold
21, 31 ... Heat transfer surface
22, 32 ... Circular holes
23, 33 ... Gas inlet
24, 34 ... Gas flow passage
25, 35 ... Gas outlet
26, 36 ... Opposing surface G ... Gas for heating

Claims (5)

A heating assembly of a heating mold heated by being thermally coupled to a heater is brought into contact with a temporary assembly assembled by interposing a brazing filler metal at a bonding interface of the members to be bonded, and the heating mold In the vicinity of the peripheral edge of the mold, the heating gas introduced into the heating mold is circulated through a gas flow passage that opens on the side of the mold, and the brazing material is melted to braze the members to be joined. Heat transfer brazing method.   The heat transfer brazing method according to claim 1, wherein the heating gas is a gas having a temperature higher than a brazing temperature.   The heat transfer brazing according to claim 1 or 2, wherein the heating mold has a square shape in plan view, and the heating gas introduced in the vicinity of the corner of the heating mold is circulated through the gas flow passage leading to the corner. How to attach.   The heat transfer brazing method according to any one of claims 1 to 3, wherein the temporary assembly is a heat exchanger that brazes fins between two members arranged to face each other. A heating mold that is heated by being thermally coupled to a heater and is brought into contact with a temporary assembly that is assembled with a brazing material interposed at a bonding interface of the members to be bonded, the peripheral end of the heating mold A heating mold for heat transfer brazing, characterized in that a gas flow passage having a discharge port on a side surface is provided in the vicinity.

Images