Method for manufacturing heat exchanger

Abstract

A method for manufacturing a heat exchanger (1) including a plurality of fins (10) arranged in the thickness direction and a plurality of heat transfer tubes (30) penetrating the plurality of fins (10), the heat transfer tubes (30) being made of aluminum, the manufacturing method including a connection step in which the fins (10) are connected to the heat transfer tubes (30), and a first brazing step in which the fins (10) are welded to the heat transfer tubes (30), and the first brazing step in which the fins (10) are welded to the heat transfer tubes (30). In a first brazing step, a first opening end (31) of opening ends (31, 32) of a heat transfer tube (30) protruding from a fin (10) is connected to a first connection tube (41) made of aluminum, and in a first brazing step, the first connection part (43) is heated by a first burner (61) that can move around the first connection part (43) that connects the first opening end (31) and the first connection tube (41), and the first connection part (43) is brazed by a second burner (61) that can move around the first connection part (43) that connects the first opening end (31) and the first connection tube (41). And the first connecting part (43) is brazed.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a heat exchanger. Background Art

[0002] Conventionally, in fin-tube heat exchangers, the open ends of heat transfer tubes protruding from stacked fins are connected to the U-shaped bends by brazing. Patent Document 1 discloses a multi-head burner in which the open ends of a plurality of heat transfer tubes are brazed to the U-shaped bends at the same time.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 2010-172943 Summary of the invention

[0006] -Technical problem to be solved by the invention-

[0007] Since aluminum is easily deformed by heating, when the raw materials of heat transfer tubes and elbows are aluminum, the heating temperature needs to be relatively strictly adjusted during brazing. Therefore, when using a multi-head burner that brazes multiple heat transfer tubes and elbows at the same time, insufficiently brazed heat transfer tubes may occur. Therefore, there is room for improvement in the manufacturing method of the heat exchanger.

[0008] The purpose of the present disclosure is to provide a method for manufacturing a heat exchanger, which can improve the brazing accuracy of aluminum heat transfer tubes.

[0009] -Technical solutions to solve technical problems-

[0010] The first aspect is a method for manufacturing a heat exchanger.

[0011] The heat exchanger includes a plurality of fins 10 arranged in a thickness direction and a plurality of heat transfer tubes 30 penetrating the plurality of fins 10, wherein the heat transfer tubes 30 are made of aluminum. The manufacturing method of the heat exchanger includes a connecting process and a first brazing process.

[0012] In the connecting step, the first open end 31 of the open ends 31 and 32 of the heat transfer tube 30 protruding from the fin 10 is connected to the first connecting tube 41 made of aluminum.

[0013] In the first brazing step, the first connection portion 43 is brazed by heating the first connection portion 43 by using the first burner 61 that is movable around the first connection portion 43 that connects the first opening end portion 31 and the first connection pipe 41 .

[0014] In the first aspect, since the heat transfer tube 30 and the first connecting tube 41 are made of aluminum, it is necessary to adjust the temperature of the first connecting portion 43 relatively carefully during heating. However, by moving the first burner 61 so that each first connecting portion 43 is heated as a whole, the brazing accuracy of the first connecting portion 43 can be improved.

[0015] The second aspect is based on the first aspect.

[0016] In the first brazing step, the flow rate of the gas used for the heating flame ejected from the first burner 61 is controlled according to the temperature of the first burner 61 .

[0017] In the first brazing process, when the temperature of the first burner 61 itself rises, the inner diameter of the injection port of the first burner 61 increases due to thermal expansion, and the gas flow rate and the gas flow pattern change. In addition, as the temperature of the first burner 61 rises, the temperature of the first connection part 43 rises due to the radiation heat of the first burner 61. In this way, the temperature of the first connection part 43 changes due to the heating due to the temperature rise of the first burner 61, but in the second aspect, the gas flow rate is controlled according to the temperature of the first burner 61. In this way, the temperature of the first connection part 43 during heating can be kept constant.

[0018] The third aspect is based on the second aspect.

[0019] The gas is a mixed gas of combustion gas and air, and the oxygen concentration of the air is 95% or more.

[0020] In the third aspect, by changing the combustion-supporting gas from air to air with a high oxygen concentration, the combustion power can be increased. As a result, the brazing time in the first brazing step can be shortened.

[0021] According to the fourth aspect, based on any one of the first to third aspects,

[0022] In the first brazing step, the flow rate of the gas used for the heating flame ejected from the first burner 61 is controlled according to the brazing state of the first connection portion 43 .

[0023] In the fourth aspect, the gas flow rate can be adjusted so that the brazing state of the first connection portion 43 is good.

[0024] The fifth aspect is based on any one of the first to fourth aspects,

[0025] The connecting process further includes the step of connecting the second open end 32 of the open ends 31 and 32 of the heat transfer tube 30 protruding from the fin 10 to a second connecting tube 42 made of aluminum and having a lower heat capacity than the first connecting tube 41.

[0026] The manufacturing method of the heat exchanger further includes a second brazing step, in which the second connection portion 44 connecting the second opening end portion 32 and the second connection pipe 42 is heated by a fixed second burner 71 to braze the second connection portion 44.

[0027] The second brazing step is performed after the first brazing step.

[0028] Since the heat capacity of the second connection pipe 42 is lower than that of the first connection pipe 41, the heat required for brazing the second connection portion 44 is less than that of the first connection portion 43. Therefore, assuming that the first brazing step is performed after the second brazing step, the solder M that has solidified in the second brazing step will melt in the first brazing step. In the fifth aspect, by performing the second brazing step after the first brazing step, re-melting of the solder of the second connection portion 44 can be suppressed.

[0029] The sixth aspect is based on any one of the first to fifth aspects,

[0030] In the first brazing step, the heat exchanger 1 is fixed by the clamping mechanism 50.

[0031] The position of the first burner 61 is adjusted according to the deviation amount of the heat exchanger 1 from a predetermined reference position.

[0032] In the sixth aspect, since the heat exchanger 1 is positioned, the distance between the first burner 61 and the first connection portion 43 can be kept constant. Thus, the brazing state can be prevented from being varied due to the first connection portion 43 .

[0033] The seventh aspect is based on the sixth aspect.

[0034] The clamping position of the heat exchanger 1 by the clamping mechanism 50 is adjusted according to the type of the heat exchanger 1 .

[0035] In the seventh aspect, even when the heat exchanger 1 is of a different model, the distance between the first burner 61 and the first connection portion 43 can be made constant. In this way, a variety of heat exchangers 1 can be manufactured.

[0036] The eighth aspect is based on any one of the first to seventh aspects,

[0037] In the first brazing step, the plurality of first connection portions 43 are brazed simultaneously using the plurality of first burners 61 .

[0038] In the eighth aspect, the time of the first brazing step can be shortened by using the plurality of first burners 61 . BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a perspective view of a heat exchanger in an embodiment;

[0040] Figure 2 is a perspective view showing an enlarged portion of a heat exchanger;

[0041] Figure 3 is a diagram showing a flow of a method for manufacturing a heat exchanger;

[0042] Figure 4 Schematic diagrams showing a state where a heat exchanger is clamped by a clamping mechanism, (A) is a perspective view, and (B) is a view of the heat exchanger viewed from above;

[0043] Figure 5 1 is a longitudinal cross-sectional view showing the connection state of the connecting pipe and the heat transfer pipe, (A) shows the state of the connection portion before brazing, and (B) shows the state of the connection portion after brazing;

[0044] Figure 6 is a block diagram showing the structure of a first brazing device;

[0045] Figure 7 is a perspective view showing a state where the first burner is brazed to the first connection portion;

[0046] Figure 8 is a schematic diagram showing the operation of the first burner;

[0047] Fig. 9 is a block diagram showing the structure of a second brazing device;

[0048] Fig.10 is a schematic diagram showing the operation of the second burner;

[0049] Fig.11 is a flow chart showing control of gas flow;

[0050] Fig.12 is a graph showing the temperature and heating time of brazing an aluminum heat transfer tube and a connecting tube;

[0051] Fig.13 is a block diagram showing the structure of a first brazing device according to a modified example;

[0052] Fig.14 : is a flowchart showing the control of the gas flow rate in a modified example. DETAILED DESCRIPTION

[0053] The embodiments of the present invention are described below with reference to the accompanying drawings. It should be noted that the following embodiments are essentially only preferred examples and are not intended to limit the present invention, its application objects or its uses. The various structures of the various embodiments, modifications, other examples, etc. described below can be combined or partially replaced within the scope of the present invention. It should be noted that the "front", "rear", "up", "down", "right" and "left" shown below refer to the front view, respectively. Figure 1 The orientation of the heat exchanger 1 is shown.

[0054] (1) Heat exchanger

[0055] like Figure 1 and Figure 2 As shown in FIG. 1 , the heat exchanger 1 of the present embodiment is a fin-tube heat exchanger. The heat exchanger 1 includes fins 10, tube sheets 20a and 20b, heat transfer tubes 30, second connecting tubes 42, and first connecting tubes 41. In the following description, an assembly in which the fins 10 and the heat transfer tubes 30 are temporarily assembled before the first connecting tubes 41 and the second connecting tubes 42 are connected is sometimes also referred to as a heat exchanger.

[0056] (1-1) Fin

[0057] The fins 10 are made of aluminum. Each fin 10 is formed into a substantially rectangular long plate shape. The heat exchanger 1 is configured into a substantially rectangular parallelepiped shape by arranging a plurality of fins 10 in the thickness direction. A plurality of holes (not shown) are formed in each fin 10 for the heat transfer tube 30 to pass through.

[0058] (1-2) Tube sheet

[0059] The tube sheets 20a and 20b include a first tube sheet 20a and a second tube sheet 20b. Each tube sheet 20a and 20b is formed into a plate having a size substantially the same as that of the fin 10. The first tube sheet 20a is arranged at the upper end of the heat exchanger 1. The second tube sheet 20b is arranged at the lower end of the heat exchanger 1. The first tube sheet 20a and the second tube sheet 20b are arranged to sandwich a plurality of fins 10 from the upper and lower directions. A plurality of through holes 21 for the heat transfer tubes 30 to pass through are formed on each tube sheet 20a and 20b. The through holes 21 are formed in a row in the left-right direction at the front and rear portions of the tube sheets 20a and 20b, respectively.

[0060] (1-3) Heat transfer tube

[0061] The heat transfer tubes 30 are made of aluminum. The plurality of heat transfer tubes 30 penetrate the two tube sheets 20a, 20b and the plurality of fins 10 in the thickness direction. Each heat transfer tube 30 is formed in a hairpin shape, and the two open ends 31, 32 of each heat transfer tube 30 protrude upward from the through hole 21 of the first tube sheet 20a. In the following description, the open ends 31, 32 refer to the portions of the heat transfer tube 30 that protrude upward from the first tube sheet 20a.

[0062] When the heat exchanger 1 is viewed from above, the open ends 31, 32 of the plurality of heat transfer tubes 30 are arranged in a row in the left-right direction at the front and rear portions of the heat exchanger 1. The open ends 31, 32 of the plurality of heat transfer tubes 30 protruding from the first tube sheet 20a include a first open end 31 and a second open end 32. Both the first open end 31 and the second open end 32 protrude from the fin 10. A first connecting pipe 41 described later is connected to the first open end 31. A second connecting pipe 42 described later is connected to the second open end 32.

[0063] (1-4) Second connecting pipe

[0064] The second connection pipe 42 is a pipe connected to the second open end 32. In other words, the second open end 32 is an open end 32 to which the second connection pipe 42 is connected among the open ends 31 and 32 protruding from the first tube plate 20a.

[0065] The two second opening ends 32 for connecting the second connecting pipe 42 are adjacent to each other. In this way, the second connecting pipe 42 connects the second opening ends 32 adjacent to each other in the left-right direction or the front-back direction. The second connecting pipe 42 is made of aluminum. The second connecting pipe 42 is formed in a U shape. The heat capacity of the second connecting pipe 42 is smaller than the heat capacity of the first connecting pipe 41, and the details will be described later.

[0066] (1-5) First connecting pipe

[0067] The first connecting pipe 41 is a pipe connected to the first opening end 31. In the present embodiment, the first opening end 31 is an opening end 31 other than the second opening end 32 of the opening ends 31 and 32 protruding from the first tube plate 20a. The first connecting pipe 41 connects the opening ends 31 that are not adjacent to each other, or connects a flow divider (not shown) and the opening end 31.

[0068] The first connecting pipe 41 is made of aluminum. The first connecting pipe 41 and the second connecting pipe 42 have the same inner diameter and outer diameter. The pipe length of the first connecting pipe 41 is longer than the pipe length of the second connecting pipe 42. Therefore, the heat capacity of the first connecting pipe 41 is greater than the heat capacity of the second connecting pipe 42.

[0069] (2) Method for manufacturing heat exchanger

[0070] The manufacturing method of the heat exchanger 1 of the present embodiment is described. The manufacturing method of the present embodiment corresponds to a plurality of heat exchangers 1. The plurality of heat exchangers 1 are different from each other in, for example, the stacking thickness of the fins 10, the number of heat transfer tubes 30, the number of first connecting tubes 41 or second connecting tubes 42, and the arrangement conditions.

[0071] like Figure 3 As shown, the manufacturing method of this embodiment includes a clamping process, a connecting process, a first brazing process, and a second brazing process. The clamping process, the connecting process, the first brazing process, and the second brazing process are sequentially performed on the heat exchanger 1 in a state where the fins 10 and the heat transfer tubes 30 are temporarily assembled. In the manufacturing method of the heat exchanger 1 of this embodiment, a manufacturing device for the heat exchanger 1 is used. The manufacturing device for the heat exchanger includes a clamping mechanism 50, a first brazing device 60, and a second brazing device 70. The details of each device are described in the following steps.

[0072] (2-1) Clamping process

[0073] like Figure 4 As shown in (A), in the clamping process, the heat exchanger 1 is fixed by the clamping mechanism 50. The clamping mechanism 50 positions the heat exchanger 1 and fixes the heat exchanger 1 so that it does not shift in the horizontal direction. By fixing the heat exchanger 1 in this way, it is possible to suppress the brazing accuracy in the first brazing process from deviating between the heat exchangers 1 (details will be described later).

[0074] like Figure 4 As shown in (B), in the clamping process of the present embodiment, the side of the heat exchanger 1 is fixed. Specifically, the clamping mechanism 50 has four plate members 51, 51, 51, 51 and retractable arms 52, 52, 52, 52 supporting each plate member 51. The clamping mechanism 50 has a clamping control unit (not shown) for controlling the movement of each arm 52. The clamping mechanism 50 clamps the heat exchanger 1 in a manner that two plate members 51, 51 clamp the heat exchanger 1 from the left and right directions, and clamps the heat exchanger 1 in a manner that another two plate members 51, 51 clamp the heat exchanger 1 from the front and back directions. In a state where the heat exchanger 1 has been fixed by the clamping mechanism 50, the heat exchanger 1 is sent to the next process.

[0075] The clamping mechanism 50 clamps the portion above the middle height position in the vertical direction of the heat exchanger 1. This can prevent the upper end of the heat exchanger 1 from swinging in the front-rear direction, so that the brazing state of the first connection portion 43 in the first brazing step is stabilized (details will be described later).

[0076] The clamping mechanism 50 of this embodiment can adjust the height position of the clamping. For example, in the case of a heat exchanger 1 of a type with a high clamping height (a large stacking thickness of the fins 10), the height of the plate members 51, 51, 51, 51 is set higher. On the other hand, in the case of a heat exchanger 1 of a type with a low clamping height, the height of the plate members 51, 51, 51, 51 is set lower. In this way, the clamping mechanism 50 corresponds to the manufacture of various types of heat exchangers 1.

[0077] (2-2) Connection process

[0078] like Figure 5 As shown in (A), the connection process is a process of connecting the first opening end 31 of the heat transfer tube 30 to the first connecting tube 41, and connecting the second opening end 32 to the second connecting tube 42. In the following description, the connection portion between the first opening end 31 and the first connecting tube 41 is referred to as the first connection portion 43. The connection portion between the second opening end 32 and the second connecting tube 42 is referred to as the second connection portion 44. Ring-shaped solder M is pre-set on the outer peripheral surface near the end of each of the first connecting tube 41 and the second connecting tube 42.

[0079] The open ends 31 and 32 of each heat transfer tube 30 are expanded in advance by bell mouth processing. In the connection process, the first connection tube 41 is inserted into the first open end 31. Similarly, the second connection tube 42 is inserted into the second open end 32. Specifically, each open end 31 and 32 has a secondary bell mouth after the diameter is expanded and a tertiary bell mouth after the diameter is further expanded at the upper end of the secondary bell mouth. Each connection tube 41 and 42 is inserted into the second bell mouth, and the solder M is arranged to be carried on the third bell mouth (opening ends 31 and 32).

[0080] Figure 5 (B) shows the state of each connection part 43, 44 after brazing by the first brazing process and the second brazing process. The heated and molten solder M flows into the gap of the first connection part 43 and the gap of the second connection part 44 and solidifies. Specifically, the solder M flows into the secondary bell mouth of the first connection part 43 and the second connection part 44. In this way, the solder M after solidification forms a solder fillet at the first connection part 43 and the second connection part 44.

[0081] (2-3) First Brazing Step

[0082] like Figure 6 and Figure 7 As shown, the first brazing step is a step of brazing the connection between the first opening end portion 31 and the first connection pipe 41. In the first brazing step, a first brazing device 60 is used. The first brazing device 60 includes a first burner 61, a temperature sensor 62, and a first control device 63.

[0083] The first burner 61 heats the first connection portion 43, which is the connection portion between the first opening end portion 31 and the first connection pipe 41. The first burner 61 is a movable burner and can move around the first connection portion 43. The first burner 61 has two movable torches 64, 64.

[0084] Each movable welding torch 64 sprays a heating flame toward one first connection portion 43. Specifically, the two movable welding torches 64 are formed into a shape of two branches, and the heating flame is blown out from the blowing outlets provided at the top ends of the movable welding torches 64. The two movable welding torches 64 are formed to approach each other from the base end toward the blowing outlets located at the top ends. In this way, the first burner 61 heats the first connection portion 43 from two directions.

[0085] The heating flame ejected from the first burner 61 uses a prescribed gas. The heating flame is ejected from the movable welding torch 64 by burning the prescribed gas. The size of the heating flame ejected from the movable welding torch 64 is adjusted by the flow rate of the prescribed gas. The prescribed gas is a mixed gas of combustion gas and air. The combustion gas is, for example, city gas. The oxygen concentration of the air is 95% or more.

[0086] The temperature sensor 62 detects the temperature of the first burner 61. Specifically, the temperature sensor 62 detects the temperature of the movable torch 64. The temperature sensor 62 outputs information indicating the detected temperature or a signal thereof to the first control device 63. The temperature sensor 62 is a radiation thermometer.

[0087] The first control device 63 controls the size of the heating flame ejected from the movable welding torch 64 and the operation of the first burner 61. The first control device 63 includes a microcomputer and a storage device storing software for operating the microcomputer. The first control device 63 is connected to various devices of the first burner 61 in a wired or wireless manner. The first control device 63 controls the operation of various devices of the first burner 61.

[0088] The first control device 63 controls the flow rate of gas supplied to the first burner 61 based on the temperature information (temperature of the first burner 61) received from the temperature sensor 62. The control of the gas flow rate will be described later.

[0089] The first control device 63 controls the operation of the first burner 61 according to a predetermined operation program. The first control device 63 has an operation program corresponding to each type (model) of the heat exchanger 1. Thus, the first control device 63 performs brazing corresponding to each model.

[0090] like Figure 8As shown, the first control device 63 moves the movable welding torch 64 so as to heat the first connection portion 43. The first burner 61 is controlled so that the movable welding torch 64 moves in the front-to-back direction and the up-down direction. Specifically, the movable welding torch 64 moves back and forth in the front-to-back direction at the upper end of the solder M while heating the vicinity of the upper end of the solder M. Thereafter, the movable welding torch 64 descends while moving back and forth in the front-to-back direction near the lower end of the solder while heating the vicinity of the lower end of the solder. In this way, the first burner 61 moves around the first connection portion 43 while brazing the first connection portion 43. The time for heating the upper portion of the solder M and the time for heating the lower portion of the solder M are appropriately set.

[0091] The distance that the movable welding torch 64 moves back and forth is substantially equal to the length of the outer diameter of the first connection portion 43. That is, when the heat exchanger 1 is viewed from above, the heating flame ejected from each movable welding torch 64 moves back and forth between the front end and the rear end of the first connection portion 43. Furthermore, since the two movable welding torches 64 heat the upper left and right parts and the lower left and right parts of the first connection portion 43, it is possible to suppress local heating of the first connection portion 43, and the overall temperature of the first connection portion 43 rises.

[0092] The first control device 63 performs control so as to maintain a predetermined distance between the blow outlet of the movable torch 64 and the first connection portion 43. This can suppress variations in brazing accuracy of the first connection portion 43 between the heat exchangers 1.

[0093] In particular, since the horizontal deviation of each heat exchanger 1 is suppressed by the clamping mechanism 50, the deviation of the brazing state of each heat exchanger 1 can be suppressed. In addition, since the upper end of the heat exchanger 1 is suppressed from swinging in the front-back direction by the clamping mechanism 50, the distance between the blowout port of the first burner 61 and the first connecting portion 43 can be kept constant. As a result, the heat applied to the first connecting portion 43 is stabilized.

[0094] (2-4) Second Brazing Process

[0095] like Fig. 9 and Fig.10 As shown, the second brazing step is a step of brazing the connection portion between the second opening end portion 32 and the second connection pipe 42. In the second brazing step, a second brazing device 70 is used. The second brazing device 70 includes a second burner 71 and a second control device 72.

[0096] The second burner 71 heats the second connection portion 44 which is the connection portion between the second opening end portion 32 and the second connection pipe 42. The second burner 71 is a fixed type burner and includes a plurality of fixed welding torches 73.

[0097] The plurality of fixed torches 73 are arranged so that the blowing outlets of the heating flames are directed toward the respective connection parts 43 and 44. Specifically, the plurality of fixed torches 73 are fixed to a predetermined fixing member (not shown) extending in the left-right direction in front of and behind the heat exchanger 1. In this way, the plurality of fixed torches 73 arranged in front of the heat exchanger 1 heat the second connection part 44 provided in the front part of the heat exchanger 1. The plurality of fixed torches 73 of the fixing member arranged in the rear part of the heat exchanger 1 heat the second connection part 44 provided in the rear part of the heat exchanger 1.

[0098] The second burner 71 reciprocates in the left-right direction. The operation of the second burner 71 is controlled by the second control device 72 .

[0099] The second control device 72 moves the second burner 71 back and forth in the left and right directions. The distance of the back and forth movement is substantially equal to the length of the outer diameter of the second connection portion 44. That is, when the heat exchanger 1 is viewed from above, each fixed welding torch 73 moves back and forth between the right end and the left end of the second connection portion 44. In this way, the entire second connection portion 44 is heated by the heating flame of each fixed welding torch 73 without any omission. The heating time of the second connection portion 44 is appropriately set.

[0100] The heat capacity of the second connection pipe 42 is smaller than the heat capacity of the first connection pipe 41. Therefore, the amount of heat applied to the second connection pipe 42 by the second burner 71 is smaller than the amount of heat applied to the first connection pipe 41 by the first burner 61.

[0101] (2-5) Gas flow control

[0102] As the temperature of the movable torch 64 of the first burner 61 rises, its inner diameter expands due to thermal expansion, and the gas flow rate changes. In addition, as the temperature of the movable torch 64 rises, the radiant heat of the movable torch 64 may affect the temperature of the first connection portion 43. In this way, the temperature change of the movable torch 64 affects the heating of the first connection portion 43.

[0103] Thus, even if the heating time is the same, the brazing accuracy of the first connection portion 43 may vary due to the temperature change of the movable welding torch 64. Therefore, it is preferable to keep the amount of heat received by the first connection portion 43 constant. In this embodiment, in the first brazing step, the gas flow rate ejected from the first burner 61 is controlled according to the temperature of the first burner 61. Fig.11 How the gas flow rate supplied to the first burner 61 is controlled will be described.

[0104] In step S11, the first control device 63 operates the first burner 61 to start heating the first connection portion 43 at a preset gas flow rate. The temperature of the first connection portion 43 is thereby increased.

[0105] In step S12, the first control device 63 determines whether a predetermined time has passed since the start of heating (heating time). If it is determined that the heating time has passed ("Yes" in step S12), step S13 is executed. If it is determined that the heating time has not passed ("No" in step S12), heating is continued and step S12 is executed again.

[0106] In step S13, the first control device 63 determines whether the temperature of the movable welding torch 64 is within the prescribed temperature range. If it is determined that the temperature of the movable welding torch 64 is within the prescribed temperature range ("Yes" in step S13), the control returns. After returning, the first brazing is performed using the gas flow rate set in step S11. If it is determined that the temperature of the movable welding torch 64 is not within the prescribed temperature range ("No" in step S13), step S14 is executed.

[0107] In step S14, the first control device 63 determines whether the temperature of the movable welding torch 64 exceeds the prescribed range. If it is determined that the temperature of the movable welding torch 64 exceeds the prescribed range ("Yes" in step S14), step S15 is executed. If it is determined that the temperature of the movable welding torch 64 has not exceeded the prescribed range ("No" in step S14), it is determined that the temperature of the movable welding torch 64 is below the prescribed temperature range, and step S16 is executed.

[0108] In step S15, the first control device 63 sets the gas flow rate to be lower than the gas flow rate in step S11. In the first brazing step performed next, brazing is performed at the gas flow rate set in step S15.

[0109] In step S16, the first control device 63 sets the gas flow rate to be higher than the gas flow rate in step S11. In the first brazing step to be performed next, brazing is performed at the gas flow rate set in step S16.

[0110] By controlling the gas flow rate in this way, it is possible to suppress the excessive amount of heat received by the first connection portion 43. Therefore, the amount of heat received by the first connection portion 43 is constant, and the brazing accuracy of each first connection portion 43 is stabilized.

[0111] (3) Features

[0112] (3-1) Feature 1

[0113] The manufacturing method of the heat exchanger 1 of this embodiment includes a connecting process and a first brazing process. In the connecting process, the first open end 31 of the aluminum heat transfer tube 30 is connected to the first aluminum connecting tube 41. In the first brazing process, the first connecting part 43 is brazed by heating the first connecting part 43 with a first burner 61 that can move around the first connecting part 43 connecting the first open end 31 and the first connecting tube 41.

[0114] like Fig.12 As shown, since the heat transfer tube 30 and the first connecting tube 41 are both made of aluminum, when heating the first connecting portion 43, strict temperature control is required compared to the case where the heat transfer tube and the connecting tube are made of copper. Specifically, when the heat transfer tube and the connecting tube are made of copper, the copper heat transfer tube and the connecting tube are difficult to deform even if overheated, so it is sufficient to heat the first connecting portion 43 until the solder is completely melted. However, for the heat transfer tube and the connecting tube made of aluminum, if overheated, the first connecting portion 43 will be deformed or damaged, and on the other hand, if the heating temperature is low, unmelted solder will remain, resulting in insufficient brazing. Moreover, for the heat transfer tube and the connecting tube made of aluminum, the temperature difference between the lower limit heating temperature at which unmelted solder does not remain and the upper limit heating temperature at which the first connecting portion 43 does not deform is relatively small. Therefore, when connecting tubes with different heat capacities are brazed to the heat transfer tubes as in the heat exchanger 1 of the present embodiment, it is preferable to make the heating conditions different according to the type of the connecting tube.

[0115] However, in the existing multi-head brazing device that simultaneously brazes the connection parts of multiple heat transfer tubes and connecting tubes, in order to braze the connecting tube with a larger heat capacity (equivalent to the first connecting tube 41 of this embodiment), it is necessary to add an auxiliary burner to compensate for the lack of heat.

[0116] However, the auxiliary burner needs to adjust the torch installation position and angle according to the heat capacity of the connecting pipe. Since the shape, number, and layout of the connecting pipe vary depending on the heat exchanger, it is necessary to add an auxiliary burner or change the torch installation position according to the model. As a result, when producing multiple models, it cannot be said that the production efficiency is good.

[0117] In addition, concentrated brazing is a brazing method that simply heats multiple connection parts uniformly, so it is difficult to fine-tune the heating for each connection part. When adding an auxiliary burner, it takes time to study the conditions for determining the optimal position, angle, etc. according to the model.

[0118] Furthermore, if the temperature of the manufacturing equipment itself rises during the manufacturing of a large number of heat exchangers, the brazing results will also vary. Although it is conceivable to adjust the brazing time according to the operating conditions of the manufacturing equipment, the brazing results are easily affected to different degrees by the shapes of the connecting pipes connected to the heat transfer pipes, so it is difficult to maintain a constant brazing accuracy.

[0119] Therefore, in this embodiment, the first connection parts 43 are heated one by one by using the movable first burner 61. By setting the heating conditions, i.e., the operation and heating time of the first burner 61, according to the shape and heat capacity of the first connection part 43, the brazing accuracy of the first connection part 43 can be improved.

[0120] Furthermore, since the first burner 61 ejects the heating flame from two directions toward the first connection portion 43 while moving back and forth in the front-back direction, the first connection portion 43 can be heated uniformly. Furthermore, since the first burner 61 sequentially heats the upper part and the lower part of the first connection portion 43, the entire first connection portion 43 can be heated without any omission. In this way, a local temperature rise of a part of the first connection portion 43 can be suppressed.

[0121] In addition, in the present embodiment, the first burner 61 can be moved around the first connection portion 43 according to the model, so it is not necessary to study the position and angle of the auxiliary burner that supplements the heat of the first connection portion 43 as in the conventional brazing device. Therefore, even if the model of the heat exchanger to be manufactured is changed, brazing corresponding to the changed model can be quickly performed. In this way, a variety of heat exchangers 1 can be manufactured in the manufacturing method of the present embodiment. Moreover, even if there are many types of heat exchangers 1 to be manufactured, the reduction in manufacturing efficiency can be suppressed.

[0122] In addition, in the present embodiment, since the heat transfer tube 30 and the first connecting tube 41 are both made of aluminum, the range between the upper limit and the lower limit of the heating temperature for brazing is relatively narrow. Therefore, when the temperature adjustment of the first connecting portion 43 is important, since the first burner 61 is a movable burner, the heating conditions can be set for each first connecting tube 41 even if the shape of the first connecting tube 41 is different. As a result, it is possible to suppress the remaining unmelted solder due to insufficient heating, the deformation of the first connecting portion 43 due to excessive heating, and the like.

[0123] Furthermore, in this embodiment, since the first brazing device 60 can set the operating conditions of the first burner 61 according to the type of the connection pipe, it is possible to suppress an increase in manufacturing man-hours compared to the conventional method that requires adjusting the auxiliary burner each time.

[0124] (3-2) Feature 2

[0125] In the method for manufacturing the heat exchanger 1 of the present embodiment, in the first brazing step, the flow rate of the gas used for the heating flame ejected from the first burner 61 is controlled according to the temperature of the first burner 61 .

[0126] As described above, when the inner diameter of the blowout port of the movable torch 64 changes due to the thermal expansion of the movable torch 64, the gas flow rate changes, and the amount of heat applied to the first connection portion 43 also changes. In addition, if the radiant heat emitted from the movable torch 64 increases, the amount of heat applied to the first connection portion 43 is also affected. Therefore, in the first brazing step, the gas flow rate is adjusted according to the temperature of the movable torch 64. In this way, even if the movable torch 64 thermally expands, the gas flow rate can be kept constant, and thus the amount of heat applied to the first connection portion 43 can be kept constant.

[0127] Furthermore, when the temperature of the manufacturing equipment itself increased by the operation of the first brazing device 60 also affects the first brazing step, the gas flow rate control of the first burner 61 can suppress the deviation of the brazing state, thereby stably producing the heat exchanger 1.

[0128] (3-3) Feature 3

[0129] In the manufacturing method of the heat exchanger 1 of the present embodiment, the gas of the heating flame of the first burner 61 is a mixed gas of combustion gas and air, and the oxygen concentration of the air is 95% or more. In the prior art, the gas of the heating flame uses a mixed gas of combustion gas and combustion-supporting gas, but by replacing the combustion-supporting gas with air with a high oxygen concentration, high firepower can be achieved. In the first brazing process, since the first burner 61 heats the first connecting parts 43 one by one, a longer brazing time is sometimes required. In the present embodiment, since the firepower of the first burner 61 can be enhanced, the first brazing time can be shortened.

[0130] (3-4) Feature 4

[0131] The manufacturing method of the heat exchanger 1 of the present embodiment further includes a second brazing step in which the second connection portion 44 is brazed by heating the second connection portion 44 with a fixed second burner 71, and the second brazing step is performed after the first brazing step. The second connection pipe 42 is made of aluminum.

[0132] Since the heat capacity of the first connection pipe 41 is larger than that of the second connection pipe 42, the heat used for brazing the first connection part 43 is greater than the heat used for brazing the second connection part 44. Therefore, if the first brazing process is performed after the second brazing process, the temperature of the second connection part 44 will rise due to the heat applied in the first brazing process, and the weld leg of the second connection part 44 that has been formed will melt. However, by performing the second brazing process after the first brazing process, the melting of the weld leg of the second connection part 44 can be suppressed (see Figure 5 ).

[0133] (3-5) Feature 5

[0134] In the method for manufacturing the heat exchanger 1 of the present embodiment, the position at which the heat exchanger 1 is clamped by the clamping mechanism 50 is adjusted according to the type of the heat exchanger 1 .

[0135] According to this embodiment, the positioning accuracy of each heat exchanger 1 can be improved by using the clamping mechanism 50. If the positioning accuracy is improved, in the first brazing step, the distance between the blowout port of the movable welding torch 64 and the first connecting portion 43 can be kept constant, and thus the amount of heat applied to the first connecting portion 43 can be kept constant. As a result, the brazing accuracy between the heat exchangers 1 can be kept constant.

[0136] Furthermore, the clamping mechanism 50 suppresses the upper end swing of the heat exchanger 1 by fixing the upper portion of the heat exchanger 1. Since the clamping mechanism 50 can change the clamping height position, the upper portion of the heat exchanger 1 can be fixed according to the heat exchanger. As a result, it is possible to manufacture a variety of heat exchangers 1.

[0137] (4) Modification

[0138] The first control device 63 of this example controls the flow rate of the prescribed gas according to the brazing state of the first connection portion 43. The prescribed gas is the same as the gas in the above-mentioned embodiment. Fig.13 As shown, the first soldering device 60 includes a camera 65. The camera 65 detects the first connection portion 43 in the heating process as image data. For example, the first soldering device 60 has data indicating the relationship between the image data of the soldering state of the first connection portion 43 and the evaluation value indicating the degree of the soldering state.

[0139] The evaluation value indicating the degree of the brazing state is a numerical value expressed in three levels, 1 to 3, for example, "1" indicates the least satisfactory brazing state, "2" indicates the most satisfactory brazing state, and "3" indicates that the temperature of the first connection portion 43 rises excessively. The first control device 63 evaluates which stage 1 to 3 the brazing state is in based on the image data received from the camera 65. The first control device 63 controls the gas flow rate based on the estimated brazing state. Fig.14 Provide explanation.

[0140] In step S21, the first control device 63 operates the first burner 61 to start heating the first connection portion 43 at a preset gas flow rate. The temperature of the first connection portion 43 is thereby increased.

[0141] In step S22, the first control device 63 determines whether a predetermined time (heating time) has passed since the start of heating. If it is determined that the heating time has passed ("Yes" in step S22), step S13 is executed. If it is determined that the heating time has not passed ("No" in step S22), heating is continued and step S22 is executed again.

[0142] In step S23, the first control device 63 evaluates the brazing state of the first connection portion 43 based on the image data received from the camera 65. Specifically, the first control device 63 determines whether the evaluation of the brazing state of the first connection portion 43 is "2". When the evaluation of the brazing state of the first connection portion 43 is "2" ("Yes" in step S23), the control returns. After returning, the first brazing is performed using the gas flow rate set in step S21. When it is determined that the evaluation of the brazing state of the first connection portion 43 is not "2" ("No" in step S23), step S24 is executed.

[0143] In step S24, the first control device 63 determines whether the evaluation of the brazing state of the first connection portion 43 is "3". When it is determined that the evaluation of the brazing state of the first connection portion 43 is "3" ("Yes" in step S24), step S25 is executed. When it is determined that the evaluation of the brazing state of the first connection portion 43 is not "3" ("No" in step S24), it is determined that the evaluation of the brazing state of the first connection portion 43 is "1", and step S26 is executed.

[0144] In step S25, the first control device 63 sets the gas flow rate to be lower than the gas flow rate in step S21. In the first brazing step performed next, brazing is performed at the gas flow rate set in step S25.

[0145] In step S26, the first control device 63 sets the gas flow rate to be higher than the gas flow rate in step S21. In the first brazing step to be performed next, brazing is performed at the gas flow rate set in step S26.

[0146] In this way, by feeding back the brazing state of the first connection portion 43 , the gas flow rate can be adjusted so that the next brazing state is good.

[0147] (5) Other Implementation Methods

[0148] The first brazing device 60 may include a plurality of first burners 61. In the first brazing step, a plurality of first connection portions 43 are brazed simultaneously using the plurality of first burners 61. This can shorten the time of the first brazing step.

[0149] Alternatively, in the first brazing step, the heat exchanger 1 is fixed by the clamping mechanism 50, and the position of the first burner 61 is adjusted according to the displacement from the reference position of the heat exchanger 1. In this way, the first burner can heat the first connection portion 43 from a certain distance.

[0150] The first brazing device 60 may also have a laser displacement meter (not shown). The laser displacement meter measures the position of the first connecting pipe 41 after being positioned by the clamping mechanism 50. When the first connecting pipe 41 deviates from the reference position (for example, when it deviates from the reference position by ±0.5 mm), the first control device 63 adjusts the distance between the blowout port of the first burner 61 and the first connecting portion 43 according to the deviation. In this way, even if the first connecting pipe 41 is offset, the distance between the first connecting portion 43 and the blowout port of the first burner 61 can be kept constant.

[0151] The gas flow rate can also be controlled by adjusting the mixture ratio of combustion gas and air.

[0152] The above describes the implementation and variations, but it should be understood that various changes can be made to the implementation and specific matters without departing from the subject and scope of the claims. In addition, as long as the functions of the objects of the present disclosure are not affected, the above implementation and variations can be appropriately combined or replaced. The words "first", "second"... mentioned above are only used to distinguish the sentences containing the above words, and are not intended to limit the number or order of the sentences.

[0153] - Industrial Applicability -

[0154] In summary, the present disclosure is useful for a method of manufacturing a heat exchanger.

[0155] - Explanation of symbols -

[0156] 1Heat exchanger

[0157] 10 fins

[0158] 30 heat transfer tubes

[0159] 31 first opening end

[0160] 31, 32 Open end

[0161] 32 second opening end

[0162] 41 first connecting pipe

[0163] 42 Second connecting pipe

[0164] 43 first connection part

[0165] 44 second connection part

[0166] 50 Clamping mechanism

[0167] 61 First Burner

[0168] 71 Second Burner

Claims

1. A method for manufacturing a heat exchanger (1), the heat exchanger (1) comprising a plurality of fins (10) arranged in a thickness direction and a plurality of heat transfer tubes (30) penetrating the plurality of fins (10), the heat transfer tubes (30) being made of aluminum, characterized in that: The manufacturing method of the heat exchanger (1) comprises a connecting step and a first brazing step. In the connecting step, a first open end (31) of the open ends (31, 32) of the heat transfer tube (30) protruding from the fin (10) is connected to a first connecting tube (41) made of aluminum. In the first brazing step, the first connection part (43) is brazed by heating the first connection part (43) connecting the first opening end (31) and the first connection pipe (41) with a first burner (61) that can move around the first connection part (43).

2. The method for manufacturing a heat exchanger according to claim 1, characterized in that: In the first brazing step, the flow rate of gas used for the heating flame ejected from the first burner (61) is controlled according to the temperature of the first burner (61).

3. The method for manufacturing a heat exchanger according to claim 2, characterized in that: The gas is a mixed gas of combustion gas and air, and the oxygen concentration of the air is 95% or more.

4. The method for manufacturing a heat exchanger according to any one of claims 1 to 3, characterized in that: In the first brazing step, the flow rate of gas used for the heating flame ejected from the first burner (61) is controlled according to the brazing state of the first connection portion (43).

5. The method for manufacturing a heat exchanger according to any one of claims 1 to 4, characterized in that: The connecting process further includes the step of connecting a second open end (32) of the open ends (31, 32) of the heat transfer tube (30) protruding from the fin (10) to a second connecting tube (42), the second connecting tube (42) being made of aluminum and having a lower heat capacity than the first connecting tube (41), The method for manufacturing the heat exchanger further includes a second brazing step, in which the second connection portion (44) is brazed by heating the second connection portion (44) connecting the second opening end portion (32) and the second connection pipe (42) with a fixed second burner (71). The second brazing step is performed after the first brazing step.

6. The method for manufacturing a heat exchanger according to any one of claims 1 to 5, characterized in that: In the first brazing step, the heat exchanger (1) is fixed by a clamping mechanism (50). The position of the first burner (61) is adjusted according to the amount of deviation of the heat exchanger (1) from a predetermined reference position.

7. The method for manufacturing a heat exchanger according to claim 6, characterized in that: The clamping position of the heat exchanger (1) by the clamping mechanism (50) is adjusted according to the type of the heat exchanger (1).

8. The method for manufacturing a heat exchanger according to any one of claims 1 to 7, characterized in that: In the first brazing step, a plurality of the first connecting portions (43) are brazed simultaneously using a plurality of the first burners (61).

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