Method for producing heat exchangers

Abstract: A method of producing heat exchangers produces two heat exchangers simultaneously in one assembly line. A tube element unit (20) has a pair of intake/outlet portions (6,7) on both ends thereof, a pair of medium passages (10) communicating between a pair of the intake/outlet portions (6,7) and a cutting portion (5) in a middle portion thereof. A pair of tanks (30) are arranged on both ends of the tube element units. The tube element units are provisionally maintained by the tanks, and after brazing, two heat exchangers are separated and formed by cutting the cutting portion (5).

Description: The present invention relates to a method for producing a laminated heat exchanger for use as a heater core, for instance, in an air conditioner for an automobile. In particular, the present invention relates to a method according to the preamble of claim 1. Such a method for producing two or more heat exchangers at a time on one assembly line is well known and shown in the specification and Fig. 1 through Fig. 3 of Japanese Patent Unexamined Publication No. 62-286632. The method for producing the heat exchanger shown in this publication includes the following steps: at a first process, a belt-like plate is formed; at a second process, a bulging portion for forming a passage and an intake opening and an outlet opening communicated with the bulging portion for forming the passage are formed a couple symmetrically in the longitudinal direction of the belt-like plate by a press; at a third process, a passage unit is made by bonding flush two belt-like plates, the passage unit having a pair of fluid passages into which a fluid medium can flow; at a fourth process, a plurality of passage units are laminated by arranging respective fins therebetween, and thus the intake openings are communicated and the outlet openings are communicated; and after brazing of the assembly in a furnace, at a fifth process, which is a last process, the laminated passage units are cut between a pair of fluid passages to separate the laminated passage units into two heat exchangers. However, in the above mentioned method of producing a heat exchanger, since the passage units are only laminated but not fixed, it is necessary to provisionally maintain the passage units with holders until they are brazed. Thus, because the longitudinal dimension of the passage unit is twice or more in comparison with that used where a single heat exchanger is formed, it is necessary for the provisional maintenance by the holders to be done at two portions at both side ends in the longitudinal direction of the heat exchanger or in three portions, further adding a central portion. There is thus the inconvenience of the provisional maintenance work with the heat exchangers taking a great deal of time and labour. Furthermore, both sides of every passage unit are clad with a solder member for brazing. The solder member melts in a furnace, and a pair of the heat exchangers are thus formed. However, in the aforementioned method, as there is a problem in that the holders and the passage units are connected by solder clad on the passage units. Thus it is difficult to separate the holders from the heat exchangers, and a side plate and other parts are necessary to prevent connections between the holders and the passage units, which is inconvenient. Accordingly, object of the present invention is to provide a method for producing heat exchangers without using holders to provisionally maintain an assembly, the assembly being comprised of tube elements and so on, in which it is easy to separate the assembly, in the case where two heat exchangers are made simultaneously on an assembly line. It is a further object to provide a method where the assembly is provisionally maintained until the heat exchangers are brazed. The above object is achieved by a method according to claim 1. Preferred embodiments are subject of the subclaims. The method of the present invention produces heat exchangers comprising a tank having an end plate and a plurality of connecting holes disposed in parallel in a laminating direction, a pair of intake/outlet portions installed in the connecting holes, tube elements having U-shaped heat exchanging medium passages connecting between the intake/outlet portions, and fins inserted between the tube elements. The method comprises the steps of (a) forming a form plate which comprises a pair of bulging portions for intake/outlet formations forming intake/outlet portions formed on both sides in the longitudinal direction of a long and narrow plate, with projections extending from between the bulging portions for the intake/outlet formations toward the middle of the plate, bulging portions for a passage formation formed around each of the projections, and a cutting unit formed in the middle in the longitudinal direction, of the long and narrow plate; (b) bonding flush two of the form plates to form a tube element unit comprising a pair of tube elements which are joined at the cutting unit, the cutting unit having a cutting portion; (c) provisionally assembling the intake/outlet portions formed on both ends of the tube element unit by inserting them into connecting holes of tanks disposed on both ends of the tube element unit, with corrugated fins put between the tube elements, to form an assembly comprising two heat exchangers; (d) brazing the assembly in a furnace; and (e) cutting the cutting portion to separate the assembly, thus producing two heat exchangers. According to the method of producing heat exchangers of this invention, since the intake/outlet portions formed on both ends in the longitudinal direction, of the tube element unit, inserted in the connecting holes of each tank, and the laminated tube elements are held by the tanks disposed on the both ends of the tube element unit, the assembly is in a provisionally maintained condition. Thus, holders become useless, and it is easy to treat the assembly. Further, a middle portion of the form plate for the heat exchanger has a pair of fin contacting portions located side by side in the middle portion, with one fin contacting portion extending from one side of the middle portion, bent up in the bulging direction of the form plate and perpendicular relative to the form plate, and another fin contacting portion next to the one fin contacting portion extending from another side of the middle portion in the bulging direction of the form plate and perpendicular relative to the form plate. Since the fin contacting portions are formed by being bent in the direction which is the same as the bulging direction of the form plate, the form plate may not be pulled toward the middle portion, and a connecting portion joining two portions of the form plate will not deform in the process of pressing the form plate. Furthermore, it is to be desired that the length of the bending fin contacting portion is more than half of distance between the cutting portions of the tube element units facing each other in the laminated direction. Since the fin contacting portions are more than half of distance between the cutting portion of the tube element units facing each other in the laminated direction, the fins may not pass through a clearance between the fin contacting portions and the fins may be held firmly. The above and other features of the invention and the concomitant advantages will be better understood and appreciated by persons skilled in the field to which the invention pertains in view of the following description, given in conjunction with the accompanying drawings, which illustrate preferred embodiments. In the drawings: Fig. 1 is a perspective view illustrating a structure of a form plate for a heat exchanger used in a first embodiment of the method according to this invention; Fig. 2 is a perspective view of a tube element unit comprising a pair of tube elements made by bonding flush two of the form plates illustrated in Fig. 1; Fig. 3 is a partial perspective view illustrating the state in which the tube elements shown in Fig. 2 are inserted into connecting holes of a tank; Fig. 4 is a perspective view illustrating the state in which the tube element units and the tanks are provisionally assembled; Fig. 5 is a perspective view illustrating the structure of a form plate for a heat exchanger used in a second embodiment of the method according to this invention; Fig. 6 is an enlarged view of a portion of a cutting unit of the form plate illustrated in Fig. 5; Fig. 7 is a perspective view illustrating the state in which tube element units which are formed by bonding flush two of the form plates illustrated in Fig. 5 are assembled; Figs. 8A and 8b are enlarged perspective partial views illustrating a portion adjacent to a cutting unit for a heat exchanger produced according to a third embodiment of the method of this invention; Fig. 9 is a schematic view illustrating a process of pressing the form plates illustrated in Fig. 1; Fig. 10 is a perspective view illustrating the structure of a form plate used in a fourth embodiment of the method according to this invention; Fig. 11 is a perspective view illustrating a tube element unit comprising a pair of tube elements formed by bonding flush two of the form plates illustrated in Fig. 10; Fig. 12 is a perspective view illustrating the state in which the tube element units illustrated in Fig. 11 and tanks are provisionally assembled; Fig. 13 is an enlarged perspective partial view illustrating the tube element units that are provisionally assembled and illustrated in Fig. 12; Fig. 14 is a partial perspective view illustrating the state in which the tube elements shown in Fig. 12 are inserted into connecting holes of a tank; Fig. 15 is a schematic view illustrating a process of pressing the form plates illustrated in Fig. 12; and Fig. 16 is a schematic view illustrating another process of pressing the form plates illustrated in Fig. 12. The following is an explanation of the embodiment according to the present invention with reference to the drawings. Fig. 1 shows a first embodiment of a form plate 2 used in method of producing a heat exchanger of this invention. The form plate 2 is a long, narrow and rectangular plate that has solder clad on both sides thereof and is made of aluminum alloy which has aluminum as a main ingredient. As shown in Fig. 1, a pair of intake/outlet portions for intake/outlet formations 6 and 7, which become the intake/outlet for heat exchanging medium, are on both sides in the longitudinal direction of the form plate and are formed by distending, for instance by pressing. A specific length of a projection 8 extends from between a pair of bulging portions for intake/outlet formations 6 and 7 formed on both sides, in the longitudinal direction of the form plate 2, opposite the side of a middle portion or cutting unit 5. Bulging portions for a passage formation 10, communicating the bulging portions for intake/outlet formations 6 and 7, are formed around the projections 8 by pressing. The cutting unit 5 is in the middle of the form plate 2 and is pressed and expanded in the bulging direction of the form plate. The unit 5 comprises fin contacting portions 13 and a cutting portion 14 connecting between the fin contacting portions 13. The form plate 2 is symmetrical with respect to the cutting unit. The fin contacting portion 13 connects between the ends of tube elements 20 to hold the ends of corrugated fins 3 when the tube elements 20 are laminated (see e.g. Fig. 4). The cutting portion 14 has a rectangular opening 15 in the middle thereof so as to be easy to cut. The tube element unit 20, as shown in Fig. 2 is formed by bonding flush two of the form plates 2. A pair of intake/outlet openings 21 and 22 are made of the bulging portions for intake/outlet formations 6 and 7 on both sides thereof, and approximately U-shaped heat exchanging medium passages 24 are made of the bulging portions for passage formation 10 on the inside. Thus two tube elements 20 are formed therein and are symmetrical with respect to the cutting unit 5. The intake/outlet openings 21 and 22 communicate with each other through the heat exchanging medium passage 24. A cutting unit 26 is formed in a middle portion 25 of the tube element unit 20 and comprises the fin contacting portions 13 and the cutting portion 14. A tank 30 is illustrated in Figs. 3 and 4 and is formed by a tank peripheral enclosure 31 whose cross section is E-shaped due to a partition plate 33 that extends in the longitudinal direction thereof, a flat shaped end plate 32 which covers an opening side of the tank peripheral enclosure 31, and a covering plate 39 which covers both sides or ends in the longitudinal direction of the tank peripheral enclosure 31. The tank 30 is formed separately from the tube element unit 20. The tank peripheral enclosure 31, the end plate 32 and the covering plate 39 are made of an aluminum alloy whose main ingredient is aluminum, and is clad solder material. The tank 30 has a distributing passage 34 and a converging passage 35 divided by the partition plate 33, an intake pipe 36 for a heat exchanging medium communicating with the distributing passage 34 and an outlet pipe 37 communicating with the converging passage 35. The end plate 32 has a plurality of connecting holes 38. The connecting holes 38 are arranged so that a pair of connecting holes 38 which are put side by side are laminated in the longitudinal direction thereof, the intake/outlet openings 21 and 22 of the tube element units 20 being inserted into and fixed in the connecting holes 38. By the intake/outlet openings 21 and 22 being inserted into and fixed in the connecting holes 38, the intake openings 21 are communicated with the distributing passage 34 and outlet openings 22 are communicated with the converging passage 35. The following is an explanation of a method of forming a heat exchanger using the tube element unit 20 and the tanks 30 as described above. At first, as shown in Fig. 3, the intake/outlet openings 21 and 22 formed on both sides of the tube element units 20 are inserted into the connecting holes 38 of the end plate 32 of the tank 30 while putting corrugated fins 3 therebetween, and a plurality of the tube element units 20 are laminated. Then, intake/outlet pipes 36 and 37 are connected to the tank 30, and an assembly 1 as shown in Fig. 4 is formed. In this case, by the intake/outlet openings 21 and 22 being formed on both sides of each tube element unit 20 and each tube element unit 20 being in a state held by the tanks 30 arranged on both sides thereof, the assembly is in a provisionally maintained state. Therefore, even when the assembly 1 is moved to be brazed in a furnace, the tanks 30 positioned on both sides of the tube element units 20 can be used as replacements for holders that are usually used for provisional maintaining the assembly. Then, the assembly 1 is brazed in the furnace. Two heat exchangers are produced by the cutting portion 26 being cut in the direction shown by an arrow A by, for instance, a saw such as a band saw, a slide-type dividing machine or by water injection. Thus the time necessary to produce with the above-mentioned method is reduced in comparison with the case of producing two respective heat exchangers, the method being able to make the process of producing the heat exchanger efficient. Fig. 5 shows an additional embodiment of a form plate 40 used in the method of producing heat exchangers of this invention. The following is an explanation of the form plate 40. Explanation is omitted of features previously described, which are marked with the same reference numbers. For instance, the bulging portion for intake/outlet formations 6 and 7, the bulging portion for passage formation 10, projection 8 and so on are similar. Explanation about different portions from the form plate 2 are provided in the following. Furthermore, in the method of producing the heat exchangers, as the form plate 40 is made by the same process as that described above, further explanation about it is omitted here. The form plate 40 has fin contacting portions 13 extending outwardly therefrom and a cutting portion 41 connecting between the fin contacting portions 13 in the middle portion 5 thereof. Further, the fin contacting portion 13 is formed so as to hold one end of the corrugated fin 3, another end of the corrugated fin 3 being held by the end plate 32. V-shaped cut portions 42 having a specific angle as shown in Fig. 6 are formed on both sides of the cutting portion 41. This specific angle is determined within a range from 10 degrees to 45 degrees by considering the level of a cutting work and identifying the cutting position. A diamond-shaped opening 43 is formed between the V-shaped cut portions 42. A measurement b between the opening 43 and the V-shaped cut portion 42 is determined to be approximately within a range from 0.5 mm to 1 mm by considering the strength necessary at the provisional assembling and working level and at cutting. Thickness of cutting portion 41 is determined to be about 1 mm by considering the strength necessary at the provisional assembling and working level and at cutting. A tube element unit 50, which has the heat exchanging medium passages 24, intake/outlet portions 21 and 22, and a cutting portion 48 positioned in the middle portion 25 is formed by bonding two form plates 40 flush to each other. The tube element units 50 are assembled to tanks 30 while putting fins therebetween, and thus an assembly as shown in Fig. 7 is formed. Two heat exchangers are separated by the cutting portions 48 of the assembly 1 being cut by a saw such as a band saw, water injection or the like. Further, as the cutting portion 48 has a cut portion 42 and an opening 43, the two heat exchangers can be separated by providing a bending force to the cutting portion 48, or it is possible to separate them by providing a pulling force on the cutting portion 48. Figs. 8A and 8B show a third embodiment with a tube element unit 55 different from the tube element units 20 and 50 and fins 3a different from the aforementioned fins 3. The following is an explanation regarding the tube element unit 55 and the fins 3a. Regarding similar features of the tube element unit in the tube element unit 55 as described above with respect to tube element unit 50, that is, the heat exchanging medium passage 24 and the projection 8, explanation of them is omitted by marking the similar features with the same reference number, and the following is an explanation of those features that are different. A fin contacting portion, like the aforementioned fin contacting portion in the middle portion 25 between the heat exchanging medium passages 24 thereof, is not formed in the tube element unit 55. Rather, the tube element unit 55 has a cutting portion 56 formed thinner than the thickness of a form plate forming the tube element unit 55 and is in the shape of a plate. Thus, surfaces of the tube element unit 55 in the laminating direction are approximately flat. A measurement of the fin 3a (not shown in the figures) is approximately equal to a longitudinal measurement of the tube element unit 55. In the previous embodiments, when the tube element units 20 or 50 are laminated by putting fins 3 therebetween, because the space between the respective tube element units is divided into two parts, two fins are needed between two tube element units. In this embodiment, because the space between the respective tube element units has one fin 3a, the work required to assemble the heat exchangers is made easier. As mentioned above, due to the method of forming the heat exchangers according to this invention, the intake/outlet portions formed on both sides in the longitudinal direction of the tube element units are connected with the connecting holes of the tanks, and thus a plurality of the laminated tube element units are held by the tanks being arranged on both sides thereof. Therefore, by only provisionally assembling the tube element units to the tanks, the assembly being provisionally maintained, the holders become unnecessary, the treatment of the assembly is convenient, and the separation of the assembly is performed easily without increasing the number of parts. What is called a pass-on method, as illustrated in Fig. 9, is used for producing the form plate. The method comprises a plurality of plates 60 being mutually connected by connecting portions 61 and moved in due order in the direction of the arrow illustrated in Fig. 9 whenever one process is completed. An embodiment of the method is explained as a process for producing the form plate 2 shown in Fig. 1. In a first process shown in Fig. 9 (1), the opening 15 is punched by the press in the middle portion 5 of a flat plate 60, which is then sent to a second process. In the second process shown in Fig. 9 (2), the middle portion 5 is pressed out by the press to form the fin contacting portions 13 and 13 on both sides of the middle portion 5. In a third process shown in Fig. 9 (3), the bulging portions for the passage formation 10, the bulging portions for the intake/outlet formation 6 and 7 are pressed out and other portions are formed. In a fourth process shown in Fig. 9 (4), the connecting portions 61 and the remainder of the plate 60 are cut down, and thus production of the form plate 2 is completed. However, this invention provides a form plate having shaped fin contacting portions able to be formed and maintain their longitudinal measurement during formation and able to surely hold the fins. The following is an explanation of this form plate. A form plate 72 as illustrated in Fig. 10 is made of an aluminum alloy whose main material is aluminum, and solder is clad on both sides thereof, similar to the form plate 2 shown in Fig. 1, and is a long and narrow rectangle to be used for producing a tube element of a heat exchanger. Bulging portions for a passage formation 80 and bulging portions for intake/outlet formations 76 and 77 communicating with the bulging portion for passage formation 80 are pressed out, for instance by pressing on both sides of the cutting portion 84. In the form plate 72, a projection 78 extends from between the bulging portions for intake/outlet formations 76 and 77. The bulging portion for passage formation 80, communicated with the bulging portions for intake/outlet formation 76 and 77, is formed around the projection 78. A brazing portion 79 is formed along the fringe of the bulging portion for passage formation 80 and the bulging portions for intake/outlet formations 76 and 77. Fin contacting portions 85 are formed at a middle portion 75 at the center in the longitudinal direction of the form plate 72. The middle portion 75 of the form plate 72 has a pair of fin contacting portions 85 arranged side by side in the lateral direction of the form plate 72. One fin contacting portion 85 extends from one specific portion of the form plate 72 as an end of one tube element and bends up in a bulging direction of the form plate 72, and another fin contacting portion 85 extends from another specific portion of the form plate 72 as an end of another tube element 90 and bends up in the bulging direction. In other words, the fin contacting portions 85 are arranged side by side in the lateral direction of the form plate 72, and cutting portions 84 are formed on the outer sides of the fin contacting portions 85. The fin contacting portions 85 are cut on three sides thereof alternately and raised up in the bulging direction. A tube element unit 90 is formed by bonding two form plates 72 flush to each other, as shown in Fig. 11. Thus, intake/outlet portions 91 and 92 are formed by the bulging portions for intake/outlet formations 76 and 77 facing each other. Medium passages 94 are formed by the bulging portions for passage formations 80 facing each other, and the tube element unit 90 having them is formed symmetrically with respect to the middle portion 75. As shown in Figs. 12 and 13, when the tube element units 90 are laminated with fins 73 inserted therebetween, the fin contacting portions 85 of the adjacent tube element units 90 extend toward and between the adjacent tube element units 90 alternately, without touching each other. The fin contacting portions 85 arranged alternately between the adjacent tube element units 90 are overlapped against the direction of wind blown into the heat exchanger. A tank 100 where the tube element units 90 are connected comprises, as shown in Figs. 12 and 14, a tank peripheral enclosure 101 whose section is E-shaped by standing a partition plate 103 in the longitudinal direction. An end plate 102, which is a flat plate, covers the open side of the tank peripheral enclosure 101, and covering plates 109 cover both ends in the longitudinal direction of the tank peripheral enclosure 101. The tank 100 is formed separately from the tube element unit 90. The tank peripheral enclosure 101, the end plate 102 and the covering plates 109 are made of an aluminum alloy whose main material is aluminum, solder being clad on both sides thereof. The tank 100 has a distributing passage 104 and a converging passage 105 divided by the partition plate 103. An intake pipe 106 for a heat exchanging medium is connected to the distributing passage 104, and an outlet pipe 107 is connected to the converging passage 105. A plurality of pairs of connecting poles 108, where the intake/outlet portions 91 and 92 of a tube element 90 are inserted, are formed in the longitudinal direction. The intake/outlet portions 91 and 92 can thus be inserted into and fixed in the connecting holes 108, the intake portion 91 communicated with the distributing passage 104 of the tank 100 and the outlet portion 92 communicated with the converging passage 105 of the tank 100. The form plate 72 is made by what is called a pass-on method, in which a plurality of plates 120 mutually connected by connecting portions 121, are moved in due order in the direction of the arrow illustrated in Fig. 15 whenever one process is completed. The production processes are explained in order as follows. Pre-formed plate 120, on which the bulging portions for passage formation 80, the projection 78 and so on have already been formed by the press, is sent to a first process. In the first process shown in Fig. 15 (1), a rectangular hole 122 elongated in a direction perpendicular to the pass-on direction, that is, in a longitudinal direction of the form plate, is formed in the middle portion 75 to make it easy to make subsequent cuts A. In a second process shown in Fig. 15 (2), cuts A are made symmetrically in the lateral direction from each point adjacent to both ends of the longitudinal direction, and cuts B are made perpendicular to the cuts A from each outer point of the cuts A. The measurement of the cut B is set as more than half the distance between the middle portions 75 of the adjacent tube element units 90 when the tube element units 90 are laminated, and the measurement of the cut A is set as about half of the lateral direction of the tube element unit 90 or less than half. In a third process shown in Fig. 15 (3), the fin contacting portions 85 are provisionally bent at an angle of 60° by making the uncut side a bending line, and then in a fourth process shown in Fig. 15 (4), the fin contacting portions 85 are further bent to a angle of 90°. Thus, the fin contacting portions 85, standing perpendicularly to the plate 120, are formed. At last, in a fifth process shown in Fig. 15 (5), the connecting portion 121 and the remainder around the plate 120 are cut down, and the form plate 72 is completed. Furthermore, after the first process, fin contacting portions 85 can be cut and bent directly by combining the third and fourth processes, and in this case the second process can be omitted. An assembly 71 of heat exchangers as shown in Fig. 12 is formed by that the intake/outlet portions 91 and 92 being inserted into and fixed in the connecting holes 108 of the tanks 100 arranged on both sides of tube element units 90, and the tube element units 90 being laminated with the fins 73 put therebetween. In the assembly 71, the fins 73 between the tube element units 90 are held by the fin contacting portions 85, as shown in Fig. 13. Then, after brazing the assembly 71 of the heat exchangers in the furnace, two heat exchangers can be produced simultaneously by cutting the cutting portion 84 and separating the two. The hole 122 is formed in the middle portion 75 in the first process shown in Fig. 15 (1) in the aforementioned embodiment. However,as for instance shown in Fig. 16, in a first process three cut B extending to the longitudinal direction of the tube element unit 72 can be made in the center and adjacent sides of the middle portion 125, with one cut A connecting one end of the middle cut B and one end of the side cut B and another cut A connecting another end of the middle cut B and one end of the another side cut B. These cuts can be made at the same time, and then, by performing the fourth and fifth processes, a pair of fin contacting portions 125 are formed. The fin contacting portions 125 thus formed have an enlarged width and an enlarged portion contacting the fins 73 so as to surely hold fins 73, thus decreasing the work of forming the hole 122 and preventing scraps, because the holes 122 are not made and it is thus not necessary to clean up the scraps. Because the structure of the form plate 72 having the fin contacting portions 125 is the same as the aforementioned embodiment, excluding the fin contacting portions 125, further an explanation is omitted and reference is made with the same reference numbers as used previously for the same parts. In the aforementioned embodiments, the fin contacting portions 85 and 125 are explained as being formed on the form plate of the tube element unit. However, it is not necessary to be thus defined in constitution, and they may be formed in a form plate used for producing two heat exchangers in which the tanks are united with tube element units simultaneously. In the above, because the fin contacting portions are formed by bending them in the same direction as the bulging direction of the bulging portion for the passage formation according to the aforementioned form plate of the heat exchanger, pulling a plate into the middle portion is avoided, thus preventing deformation of the connecting portion connecting between the plates in the processes for producing the form plate. According to the form plate of the heat exchanger, since the fin contacting portions are more than half of the distance between the middle portions of adjacent tube element units, the fin contacting portions of adjacent tube element units are overlapped in the wind pass direction of the heat exchanger, preventing the fins from being inserted into the gap between the fin contacting portions.

Claims: Method for producing two heat exchangers, wherein each heat exchanger comprises a tank (30, 100), tube elements each having a pair of intake and outlet portions (21, 22, 91, 92) and a U-shaped heat exchanging medium passage (24. 94) communicating between said intake and outlet portions (21, 22, 91, 92), and fins (3, 3a, 73) located between the tube elements, wherein said method comprises the steps of: (a) forming a plurality of form plates (2, 40, 72), such that each comprises a middle portion (5, 75) provided at a centre portion in a longitudinal direction thereof, two bulging portions for intake/outlet formation (6, 7, 76, 77) provided at both ends in the longitudinal direction for forming said intake and outlet portions (21, 22, 91, 92), two bulging projections (8, 78) extending towards said middle portion (5, 75), two portions for a passage formation (10, 80) formed around said projections (8, 78) for forming two heat exchanging medium passages (24, 94), and a cutting portion (14, 41, 56, 84) formed in said middle portion (5, 75); (b) bonding flush pairs of said form plates (2, 40, 72) to form tube element units (20, 50, 55, 90), wherein each tube element unit (20, 50, 55, 90) comprises a pair of tube elements, which extend to the cutting portion (14, 41, 56, 84), and to form the intake and outlet portions (21, 22, 91, 92) at the tube elements; (c) forming a provisional assembly (1, 71), wherein the fins (3, 3a, 73) are located between the tube element units (20, 50, 55, 90); (d) brazing the provisional assembly (1, 71) in a furnace; and (e) cutting the cutting portions (14, 41, 56, 84) so as to separate the provisional assembly (1. 71) and form two separate heat exchangers; characterized in that the provisional assembly (1, 71) of two heat exchangers is formed by inserting the intake and outlet portions (21, 22, 91, 92) formed on both ends of the tube element units (20, 50, 55, 90) into connecting holes (38, 108) provided in end plates (32, 102) extending in laminating direction and forming parts of the tanks (30, 100) located on both longitudinal sides of the tube element units (20. 50, 55, 90). Method according to claim 1, characterized in that said cutting portion (14, 41) is pressed out from the form plate (2, 40) in a convex shape, wherein the cutting portion (14, 41) has a flat surface. Method according to claim 2, characterized in that a rectangular opening (15) is formed in said cutting portion (14). Method according to claim 1 or 2, characterized in that V-shaped cut portions (42) with a specific angle are cut on both sides of the cutting portion (41). Method according to claim 4, characterized in that said V-shaped cut portions (42) are cut with a specific angle in the range of 10 degrees to 45 degrees. Method according to claim 4 or 5, characterized in that a diamond-shaped opening (43) is provided between the V-shaped cut portions (42). Method according to claim 1, characterized in that the thickness of the cutting portion (56) is made thinner than other portions of the form plate. Method according to claim 7, characterized in that a rectangular opening is formed in the cutting portion (56). Method according to claim 1, characterized in that a pair of fin contacting portions (85, 125) is arranged at the middle portion (75) of each form plate (72) side by side in a lateral direction of the form plate (72), wherein one fin contacting portion (85, 125) is cut and bent perpendicularly to the form plate (80) and the other fin contacting portion (85, 125) is cut and bent in the opposite direction. Method according to claim 9, characterized in that the fin contacting portion (85, 125) is bent with a length that is greater than half of the distance between the middle portions (75) of adjacent tube element units (90).

Inventors: ETO YOSHIHISA, KUWABARA SHOJI, SUGITA TAKASHI, TSUBAKIDA TOSHIO, ETO, YOSHIHISA, KUWABARA, SHOJI, SUGITA, TAKASHI, TSUBAKIDA, TOSHIO, Eto, Yoshihisa, c/o Zexel Corp. Konan Fact., Kuwabara, Shoji, c/o Zexel Corp. Konan Fact., SUGITA, TAKASHI, C/O ZEXEL CORP. KONAN FACT., Tsubakida, Toshio, c/o Zexel Corp. Konan Fact.
Applicants: ZEXEL CORP, ZEXEL CORPORATION
Application year: 1995
Main classification: B21D53
IPC codes: B21D53, F28D1