HEAT EXCHANGER MANUFACTURING METHOD AND DIAMETER ENLARGEMENT TOOL

Abstract

A heat exchanger manufacturing method, including rolling a metal sheet into a roll shape to form a tube-shaped body, inserting the tube-shaped body through a through hole formed at a metal fin, and loosening the metal sheet that has been rolled into a roll shape to enlarge the diameter of the tube-shaped body and place an outer peripheral face of the tube-shaped body in contact with a hole wall of the through hole, and after enlarging the diameter, joining together a roll-overlap portion of the metal sheet that has been rolled into a roll shape.

Description

TECHNICAL FIELD

The present invention relates to a heat exchanger manufacturing method and a diameter enlargement tool.

BACKGROUND ART

Japanese Patent Application Laid-Open (JP-A) No. 2011-257084 describes a method of inserting a tube-shaped body (heat transfer tube) formed by extruding aluminum in a tube shape through insertion holes formed in fins, and then inserting a diameter enlargement tool (pipe enlargement tool) inside the tube-shaped body to enlarge the external diameter of the tube-shaped body.

SUMMARY OF INVENTION

Technical Problem

However, in the method described in JP-A No. 2011-257084, the diameter enlargement tool is used to stretch the tube-shaped body in the circumferential direction (stretch around the perimeter) in order to enlarge the external diameter, and so a large load is required to enlarge the diameter of the tube-shaped body.

In consideration of the above circumstances, an object of the present invention is to provide a heat exchanger manufacturing method and a diameter enlargement tool enabling a reduction in the load required to enlarge the diameter of the tube-shaped body.

Solution to Problem

A heat exchanger manufacturing method of a first aspect of the present invention includes a forming process of rolling a metal sheet into a roll shape to form a tube-shaped body, a diameter enlargement process of inserting the tube-shaped body through a through hole formed at a metal fin, and loosening the metal sheet that has been rolled into a roll shape to enlarge the diameter of the tube-shaped body and place an outer peripheral face of the tube-shaped body in contact with a hole wall of the through hole, and a joining process of, after the diameter enlargement process, joining together a roll-overlap portion of the metal sheet that has been rolled into a roll shape.

In the heat exchanger manufacturing method of the first aspect, the metal sheet is rolled up into a roll shape to form the tube-shaped body, and the metal sheet rolled up into a roll shape is loosened to enlarge the diameter of the tube-shaped body. This enables the load required to enlarge the diameter of the tube-shaped body to be reduced compared to a configuration where an extrusion-formed heat transfer tube is stretched in the circumferential direction (stretched around the perimeter) to enlarge the diameter.

A heat exchanger manufacturing method of a second aspect of the present invention is the heat exchanger manufacturing method of the first aspect in which, in the diameter enlargement process, a diameter enlargement tool, with an external diameter that is larger than an internal diameter of the tube-shaped body prior to diameter enlargement, is inserted inside the tube-shaped body to forcibly loosen the metal sheet that has been rolled into a roll shape and enlarge the diameter of the tube-shaped body.

In the heat exchanger manufacturing method of the second aspect, in the diameter enlargement process, the diameter enlargement tool, with an external diameter that is larger than the internal diameter of the tube-shaped body prior to diameter enlargement, is inserted inside the tube-shaped body pre-diameter enlargement to forcibly loosen the metal sheet rolled up into a roll shape and enlarge the diameter of the tube-shaped body. Namely, employing the diameter enlargement tool with an external diameter larger than the internal diameter of the tube-shaped body pre-diameter enlargement enables the diameter of the tube-shaped body to be enlarged in a simple manner.

A heat exchanger manufacturing method of a third aspect of the present invention is the heat exchanger manufacturing method of the second aspect in which, the metal sheet has an undulating portion formed on one sheet face and, in the forming process, the metal sheet is rolled into a roll shape to form the tube-shaped body with the undulating portion at an inner side thereof.

In the heat exchanger manufacturing method of the third aspect, the metal sheet is rolled up into a roll shape with the undulating portion formed on the one face on the inside to form the tube-shaped body with the undulating portion at an inner peripheral face. Forming the undulating portion in this manner increases the surface area of the inner peripheral face of the tube-shaped body, improving heat transfer efficiency between the tube-shaped body and fluid passing through inside the tube-shaped body.

Note that the heat exchanger manufacturing method described above enables a reduction in the load required to enlarge the diameter of the tube-shaped body, thereby enabling deformation (squashing deformation) of the undulating portion formed at the inner peripheral face of the tube-shaped body to be suppressed when using the diameter enlargement tool to enlarge the diameter of the tube-shaped body. This enables heat transfer efficiency to be secured between the tube-shaped body and the fluid passing through inside the tube-shaped body.

A heat exchanger manufacturing method of a fourth aspect of the present invention is the heat exchanger manufacturing method of either the second aspect or the third aspect in which the metal sheet is configured by aluminum.

In the heat exchanger manufacturing method of the fourth aspect, the metal sheet rolled up into a roll shape to form the tube-shaped body is configured by aluminum, thereby enabling a reduction in weight and a reduction in costs, while securing heat transfer efficiency between the tube-shaped body and the fluid passing through inside the tube-shaped body. Moreover, configuring the metal sheet by aluminum enables the load required to enlarge the diameter of the tube-shaped body to be reduced compared to cases in which the metal sheet is configured by a material that deforms less readily, such as a steel sheet. Deformation (squashing deformation) of an undulating portion formed at the inner peripheral face of the tube-shaped body can accordingly be further suppressed when enlarging the diameter of the tube-shaped body with the diameter enlargement tool.

A heat exchanger manufacturing method of a fifth aspect of the present invention is the heat exchanger manufacturing method of any one of the second aspect to the fourth aspect in which the diameter enlargement tool includes a circular column-shaped main body that is inserted inside the tube-shaped body, ribs that are provided at intervals in a circumferential direction around an outer peripheral face of the main body, that project outward from the main body outer peripheral face, that extend from an end portion of the main body at an insertion direction side toward an opposite side to the insertion direction, and that contact an inner peripheral face of the tube-shaped body, and inclined portions that are formed at insertion direction leading end portions of the ribs, and that have a projection height from the main body outer peripheral face that gradually increases toward the opposite side to the insertion direction.

In the heat exchanger manufacturing method of the fifth aspect, the ribs of the diameter enlargement tool contact the inner peripheral face of the tube-shaped body, thereby enabling a reduction in the contact surface area between the diameter enlargement tool and the inner peripheral face of the tube-shaped body, enabling a reduction in resistance from deformation of the tube-shaped body when inserting the diameter enlargement tool into the tube-shaped body. The load required to insert the diameter enlargement tool into the tube-shaped body can accordingly be reduced.

The leading end portions of the ribs in the insertion direction are formed with the inclined portions whose projection height from the outer peripheral face of the main body gradually increases on progression toward the opposite side to the insertion direction. The inclined portions accordingly act as guides for enlarging the diameter of the tube-shaped body when the diameter enlargement tool is inserted into the tube-shaped body pre-diameter enlargement. This enables smoother insertion of the diameter enlargement tool into the tube-shaped body than a rib configuration that does not include the inclined portions.

A heat exchanger manufacturing method of a sixth aspect of the present invention is the heat exchanger manufacturing method of the fifth aspect in which the ribs extend in a spiral shape toward the opposite side of the main body to the insertion direction, with the direction of the spiral being set as an opposite direction to a roll-up direction of the metal sheet that has been rolled into a roll shape.

In the heat exchanger manufacturing method of the sixth aspect, the ribs extend in a spiral shape toward the side of the main body opposite to the insertion direction, with the direction of the spiral set as the opposite direction to the roll-up direction of the metal sheet rolled up into a roll shape. The metal sheet rolled up into a roll shape is accordingly imparted with force from the ribs in the opposite direction to the roll-up direction and is loosened when the diameter enlargement tool is inserted into the tube-shaped body. The load required to enlarge the diameter of the tube-shaped body can accordingly be reduced.

A heat exchanger manufacturing method of a seventh aspect of the present invention is the heat exchanger manufacturing method of the fifth aspect in which the ribs extend in straight line shapes toward the opposite side of the main body to the insertion direction, and an interval between respective contact portions, at which two of the ribs disposed on either side of a peripheral inside edge portion of the metal sheet that has been rolled into a roll shape contact the inner peripheral face of the tube-shaped body, widens toward the opposite side to the insertion direction.

In the heat exchanger manufacturing method of the seventh aspect, the separation between respective contact portions where two of the ribs disposed on each side of a peripheral inside end portion of the metal sheet rolled up into a roll shape contact the inner peripheral face of the tube-shaped body widens on progression toward the opposite side to the insertion direction. When the diameter enlargement tool is inserted into the tube-shaped body, the peripheral inside edge portion of the metal sheet rolled up into a roll shape is accordingly imparted with force from the two ribs in the opposite direction to the roll-up direction, and moves in the circumferential direction of the tube-shaped body, thereby loosening the metal sheet rolled up into a roll shape. This enables the load required to enlarge the diameter of the tube-shaped body to be reduced.

A diameter enlargement tool of an eighth aspect of the present invention is a diameter enlargement tool to enlarge the diameter of a tube-shaped body formed by rolling a metal sheet into a roll shape, the diameter enlargement tool including a circular column-shaped main body that is inserted inside the tube-shaped body, ribs that are provided at intervals in a circumferential direction around an outer peripheral face of the main body, that project outward from the main body outer peripheral face, that extend from an end portion of the main body at an insertion direction side toward an opposite side to the insertion direction, and that contact an inner peripheral face of the tube-shaped body, and inclined portions that are formed at insertion direction leading end portions of the ribs, and that have a projection height from the main body outer peripheral face that gradually increases toward the opposite side to the insertion direction, wherein an external diameter of the diameter enlargement tool is larger than an internal diameter of the tube-shaped body.

In the diameter enlargement tool of the eighth aspect, the external diameter of the diameter enlargement tool is larger than the internal diameter of the tube-shaped body, such that inserting the diameter enlargement tool into the tube-shaped body forcibly loosens the metal sheet rolled up into a roll shape and enlarges the diameter of the tube-shaped body. Note that during insertion of the diameter enlargement tool, the ribs contact the inner peripheral face of the tube-shaped body, thereby enabling a reduction in the contact surface area between the diameter enlargement tool and the inner peripheral face of the tube-shaped body. Resistance due to deformation of the tube-shaped body when inserting the diameter enlargement tool into the tube-shaped body can accordingly be reduced. This enables a reduction in the load required to insert the diameter enlargement tool into the tube-shaped body. The load required to enlarge the diameter of the tube-shaped body can be reduced as a result.

Advantageous Effects of Invention

As described above, the heat exchanger manufacturing method and the diameter enlargement tool of the present invention enable a reduction in the load required to enlarge the diameter of a tube-shaped body.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-section taken along the axial direction of a tube-shaped body to explain a diameter enlargement process of a heat exchanger manufacturing method of a first exemplary embodiment.

FIG. 2 is a cross-section taken along line 2X-2X in FIG. 1.

FIG. 3 is a cross-section taken along line 3X-3X in FIG. 1.

FIG. 4A is a perspective view illustrating a diameter enlargement tool employed in a heat exchanger manufacturing method of the first exemplary embodiment.

FIG. 4B is a front view of the diameter enlargement tool illustrated in FIG. 4A.

FIG. 4C is a side view of the diameter enlargement tool illustrated in FIG. 4A.

FIG. 5 is a cross-section taken along the axial direction of a tube-shaped body of a heat exchanger manufactured using a heat exchanger manufacturing method of the first exemplary embodiment.

FIG. 6A is a perspective view illustrating a first modified example of a diameter enlargement tool employed in the first exemplary embodiment.

FIG. 6B is a front view of the diameter enlargement tool of the first modified example illustrated in FIG. 6A.

FIG. 6C is a side view of the diameter enlargement tool of the first modified example illustrated in FIG. 6A.

FIG. 7A is a perspective view illustrating a second modified example of a diameter enlargement tool employed in the first exemplary embodiment.

FIG. 7B is a front view of the diameter enlargement tool of the second modified example illustrated in FIG. 7A.

FIG. 7C is a side view of the diameter enlargement tool of the second modified example illustrated in FIG. 7A.

FIG. 8A is a perspective view illustrating a third modified example of a diameter enlargement tool employed in the first exemplary embodiment.

FIG. 8B is a front view of the diameter enlargement tool of the third modified example illustrated in FIG. 8A.

FIG. 8C is a side view of the diameter enlargement tool of the third modified example illustrated in FIG. 8A.

FIG. 9 is a cross-section taken along an axis-orthogonal direction of a tube-shaped body employed in a heat exchanger of a heat exchanger manufacturing method of a second exemplary embodiment.

FIG. 10 is a cross-section taken along an axis-orthogonal direction (corresponding to a cross-section taken along line 2X-2X of FIG. 1) of a tube-shaped body pre-diameter enlargement to explain a diameter enlargement process of a heat exchanger manufacturing method of the second exemplary embodiment.

FIG. 11 is a cross-section taken along an axis-orthogonal direction (corresponding to a cross-section taken along line 3X-3X of FIG. 1) of a tube-shaped body after diameter enlargement to explain a diameter enlargement process of the heat exchanger manufacturing method illustrated in FIG. 10.

DESCRIPTION OF EMBODIMENTS

Explanation follows regarding exemplary embodiments of a heat exchanger manufacturing method and a diameter enlargement tool according to the present invention, with reference to the drawings.

First Exemplary Embodiment

FIG. 5 illustrates a heat exchanger 20 manufactured by a heat exchanger manufacturing method of a first exemplary embodiment. The heat exchanger 20 of the present exemplary embodiment is installed in an air conditioner, and is employed in heat exchange with a fluid employed in a heat exchange section of the air conditioner. Note that the present invention is not limited to such a configuration, and the heat exchanger 20 may be installed in a refrigerator and employed to cool a coolant (an example of a fluid) employed in a cooling section of the refrigerator, or may be installed to a vehicle and employed to cool coolant water (an example of a fluid) in an engine cooling device. Namely, the heat exchanger 20 of the present exemplary embodiment may be applied to any equipment that performs heat exchange with a fluid.

As illustrated in FIG. 5, the heat exchanger 20 of the present exemplary embodiment includes a heat transfer tube 30 and fins 40. The heat transfer tube 30 is an example of a tube-shaped body of the present invention.

As illustrated in FIG. 2 and FIG. 3, the heat transfer tube 30 is formed by bending a single metal sheet 31. Specifically, the heat transfer tube 30 is formed by rolling up the single metal sheet 31 into a roll shape and joining together at a roll-overlap portion. The heat transfer tube 30 of the present exemplary embodiment is a double-walled rolled tube configured by rolling the metal sheet 31 around twice. In the heat transfer tube 30, part of an inner face 31B of the metal sheet 31 rolled up into a roll shape configures a tube inner face 30B, and part of an outer face 31A of the metal sheet 31 rolled up into a roll shape configures a tube outer face 30A. The tube outer face 30A indicates the outer peripheral face of the heat transfer tube 30, and the tube inner face 30B indicates the inner peripheral face of the heat transfer tube 30. In the drawings, the axial direction of the heat transfer tube 30 is indicated by the direction of arrow A.

The inner face 31B of the metal sheet 31 rolled up into a roll shape is formed with an inside stepped face 32B between a peripheral inside edge portion 31C and a peripheral outside edge portion 31D. The edge portion 31C of the metal sheet 31 rolled up into a roll shape is joined to the inside stepped face 32B.

The outer face 31A of the metal sheet 31 rolled up into a roll shape is formed with an outside stepped face 32A between the edge portion 31C and the edge portion 31D. The edge portion 31D of the metal sheet 31 rolled up into a roll shape is joined to the outside stepped face 32A.

In a manufacturing method of the heat exchanger 20 of the present exemplary embodiment, described later, an intermediate portion (roll-up direction intermediate portion) between the edge portion 31C and the edge portion 31D of the metal sheet 31 rolled up into a roll shape is bent into a substantially crank shape, forming a stepped portion 32. One face (the face configuring the inner face 31B) of the thus formed stepped portion 32 configures the inside stepped face 32B, and the other face (the face configuring the outer face 31A) configures the outside stepped face 32A.

The metal sheet 31 forming the heat transfer tube 30 is a metal sheet with a core formed from a metal material affixed with a covering member formed from a metal material with a lower melting point than the core, namely a clad sheet. In the present exemplary embodiment, the metal sheet 31 is configured by aluminum. Specifically, the metal sheet 31 is formed by affixing a covering member formed from an aluminum alloy (for example, aluminum impregnated with silicon) to a core formed from pure aluminum. The covering member forms the outer face 31A of the metal sheet 31 rolled up into a roll shape. The covering member is moreover employed as a joining material (brazing filler) for joining together the roll-overlap portion of the metal sheet 31 rolled up into a roll shape. The core forms the inner face 31B of the metal sheet 31 rolled up into a roll shape.

Note that in the present exemplary embodiment, the metal sheet 31 is configured by aluminum, however the present invention is not limited to such a configuration, and the metal sheet 31 may be configured from a metal material such as copper or iron.

As illustrated in FIG. 5, the fins 40 are configured by forming a metal material (for example aluminum) into plate shapes. The fins 40 are formed with through holes 42 penetrating in the plate thickness direction. Specifically, the through holes 42 are formed in the fins 40 by burring. The heat transfer tube 30 is inserted through the through holes 42, and the tube outer face 30A, that is the outer peripheral face of the heat transfer tube 30, is joined to hole walls 42A. Note that in the present exemplary embodiment, the tube outer face 30A of the heat transfer tube 30 is joined to hole walls 42A configuring inner walls of ring shaped stand-out portions 44 formed by burring the fins 40.

Next, detailed explanation follows regarding the heat exchanger 20. In the heat exchanger 20, plural of the heat transfer tubes 30 are arranged parallel to each other in a row, and end portions of adjacent heat transfer tubes 30 are coupled together by U-shaped tube connectors. Each of the heat transfer tubes 30 is inserted through respective through holes 42 of the plural fins 40, and the respective tube outer faces 30A are joined to the respective hole walls 42A.

Explanation follows regarding a manufacturing method of the heat exchanger 20 according to the first exemplary embodiment of the present invention.

Forming Process

First, the flat plate shaped metal sheet 31 is prepared, with the covering member affixed to the core. The metal sheet 31 is rolled up into a roll shape to form the heat transfer tube 30 (pre-diameter enlargement heat transfer tube) that is an example of a tube-shaped body (see FIG. 2). Specifically, the metal sheet 31 is rolled up into a roll shape using a roll forming machine, namely by roll forming, to form the heat transfer tube 30. In the forming process, the metal sheet 31 is rolled up into a roll shape such that the external diameter of the heat transfer tube 30 is smaller than the diameter of the through holes 42 formed in the fins 40 (see FIG. 1).

Diameter Enlargement Process

Next, the metal sheet 31 rolled up into a roll shape is inserted through the through holes 42 formed in the fins 40. The metal sheet 31 rolled up into a roll shape is then loosened to enlarge the diameter of the heat transfer tube 30, placing the tube outer face 30A of the heat transfer tube 30 in contact with the hole walls 42A of the through holes 42 of the fins 40. Specifically, as illustrated in FIG. 1, a diameter enlargement tool 50 with a larger external diameter than the internal diameter of the heat transfer tube 30 pre-diameter enlargement is inserted inside the pre-diameter enlargement heat transfer tube 30, forcibly loosening the metal sheet 31 rolled up into a roll shape to enlarge the diameter of the heat transfer tube 30. The external diameter of the diameter enlargement tool 50 is set at a size to enlarge the diameter of the heat transfer tube 30 far enough for the tube outer face 30A to contact the hole walls 42A.

During diameter enlargement of the heat transfer tube 30, as illustrated in FIG. 3, the stepped portion 32 is formed between the edge portion 31C and the edge portion 31D of the metal sheet 31 rolled up into a roll shape. When this is performed, the edge portion 31C is disposed facing the inside stepped face 32B of the stepped portion 32, and the edge portion 31D is disposed facing the outside stepped face 32A of the stepped portion 32.

Joining Process

Next, the metal sheet 31 rolled up into a roll shape is heated together with the fins 40, melting the covering member, and then the covering member is cooled and hardened in a close contact state of the roll-overlap portion of the metal sheet 31 rolled up into a roll shape, thereby joining (brazing) the roll-overlap portion of the metal sheet 31 rolled up into a roll shape. When this is performed, the covering member forming the outer periphery of the metal sheet 31 rolled up into a roll shape is also joined to the hole walls 42A of the through holes 42. The heat exchanger 20 is thereby formed.

Next, explanation follows regarding the diameter enlargement tool 50 employed in the manufacturing method of the heat exchanger 20 of the present exemplary embodiment.

As illustrated in FIG. 1 and FIG. 4A to FIG. 4C, the diameter enlargement tool 50 is configured including a circular column-shaped main body 52 that is inserted inside the heat transfer tube 30, ribs 54 provided at an outer peripheral face 52A of the main body 52, and inclined portions 56 formed at insertion direction leading end portions of the ribs 54. The insertion direction of the main body 52 is the same direction as the insertion direction of the diameter enlargement tool 50, and the insertion direction of the main body 52 is indicated by the direction of arrow B in the drawings.

The ribs 54 project out from the outer peripheral face 52A of the main body 52, and extend from the insertion direction leading end side of the main body 52 toward the opposite side to the insertion direction. Plural of the ribs 54 are provided at intervals around the circumferential direction of the main body 52 (the direction indicated by arrow C in the drawings). Apex portions 54A of the ribs 54 are configured so as to contact the tube inner face 30B of the heat transfer tube 30. The external diameter of the diameter enlargement tool 50 refers to the external diameter of a circle that passes through the locations of the ribs 54 most distant from the axial center of the main body 52 (portions of the apex portions 54A).

The ribs 54 extend in straight line shapes toward the opposite side to the insertion direction of the main body 52. A separation L between respective contact portions where two of the ribs 54, disposed on each side of the edge portion 31C of the metal sheet 31 rolled up into a roll shape, contact the tube inner face 30B of the heat transfer tube 30 widens on progression toward the opposite side to the insertion direction of the main body 52.

The inclined portions 56 are configured such that their projection height from the outer peripheral face 52A of the main body 52 becomes gradually higher on progression toward the opposite side to the insertion direction of the main body 52.

A rod 58, extending from a drive device that inserts the main body 52 into the heat transfer tube 30, is coupled to the diameter enlargement tool 50.

Explanation follows regarding operation and advantageous effects of the manufacturing method of the heat exchanger 20 of the present exemplary embodiment.

In the manufacturing method of the heat exchanger 20 of the present exemplary embodiment, the metal sheet 31 is rolled up into a roll shape to form the heat transfer tube 30, and then the metal sheet 31 rolled up into a roll shape is loosened to enlarge the diameter of the heat transfer tube 30. The load required to enlarge the diameter of the heat transfer tube 30 can accordingly be reduced compared to in a configuration where an extrusion-formed extruded heat transfer tube is stretched in the circumferential direction (stretched around the perimeter) to enlarge the diameter.

Specifically, in the diameter enlargement process of the manufacturing method of the heat exchanger 20, the diameter enlargement tool 50 that has a larger external diameter than the internal diameter of the heat transfer tube 30 pre-diameter enlargement is inserted inside the heat transfer tube 30, and the metal sheet 31 rolled up into a roll shape is forcibly loosened to enlarge the diameter of the heat transfer tube 30. Namely, employing the diameter enlargement tool 50 with a larger external diameter than the internal diameter of the heat transfer tube 30 pre-diameter enlargement enables simple diameter enlargement in the heat transfer tube 30.

During diameter enlargement of the heat transfer tube 30, the ribs 54 of the diameter enlargement tool 50 contact the tube inner face 30B of the heat transfer tube 30, thereby enabling a reduction in the contact surface area between the diameter enlargement tool 50 and the tube inner face 30B of the heat transfer tube 30, and enabling a reduction in resistance due to deformation of the heat transfer tube 30 when the diameter enlargement tool 50 is inserted into the heat transfer tube 30. The load required to insert the diameter enlargement tool 50 into the heat transfer tube 30 can accordingly be reduced.

The leading end portions of the ribs 54 in the insertion direction of the main body 52 are formed with the inclined portions 56 whose projection height from the outer peripheral face 52A of the main body 52 gradually increases on progression toward the opposite side to the insertion direction. Accordingly, during insertion of the diameter enlargement tool 50 into the heat transfer tube 30 pre-diameter enlargement, the inclined portions 56 act as guides for the diameter enlargement of the heat transfer tube 30. The diameter enlargement tool 50 can accordingly be inserted smoothly into the heat transfer tube 30.

Moreover, during diameter enlargement of the heat transfer tube 30, the separation L between the respective contact portions where the two ribs 54 disposed on each side of the edge portion 31C of the metal sheet 31 rolled up into a roll shape contact the tube inner face 30B of the heat transfer tube 30 widens on progression toward the opposite side of the main body 52 to the insertion direction. Accordingly, when the diameter enlargement tool 50 is inserted into the heat transfer tube 30, the edge portion 31C of the metal sheet 31 rolled up into a roll shape is imparted with force from the two ribs 54 in the opposite direction to the roll-up direction and moves in the heat transfer tube 30 circumferential direction (indicated by the arrow D in the drawings), thereby loosening the metal sheet 31 rolled up into a roll shape. This enables a reduction in the load required for diameter enlargement of the heat transfer tube 30.

In the manufacturing method of the heat exchanger 20, the metal sheet 31 rolled up into a roll shape to form the heat transfer tube 30 is configured by aluminum, thereby enabling a reduction in weight and reduction in costs of the heat exchanger 20 while securing heat transfer efficiency between the heat transfer tube 30 and the fluid passing through the heat transfer tube 30. Configuring the metal sheet 31 by aluminum enables, for example, a reduction in the load required for diameter enlargement of the heat transfer tube 30 in comparison to when the metal sheet 31 is formed from a material that does not deform so readily, such as steel sheet.

In the present exemplary embodiment, the diameter enlargement tool 50 is used to enlarge the diameter of the heat transfer tube 30 formed by rolling up the metal sheet 31 into a roll shape, however the present invention is not limited to such a configuration. For example, the diameter of the heat transfer tube 30 may be enlarged using a diameter enlargement tool 60 of a first modified example, a diameter enlargement tool 70 of a second modified example, or a diameter enlargement tool 80 of a third modified example of the diameter enlargement tool 50, respectively described below. Note that the diameter enlargement tool 60 of the first modified example, the diameter enlargement tool 70 of the second modified example, and the diameter enlargement tool 80 of the third modified example may also be employed in the manufacturing method of a heat exchanger 22 of a second exemplary embodiment, described later.

As illustrated in FIG. 6A to FIG. 6C, in the diameter enlargement tool 60 of the first modified example, ribs 64 projecting out from the outer peripheral face 52A of the main body 52 extend in straight line shapes from an end portion of the main body 52 on the insertion direction side toward the opposite side to the insertion direction. Plural of the ribs 64 are provided at uniform separations around the circumferential direction of the main body 52. Accordingly, during insertion of the diameter enlargement tool 60 into the heat transfer tube 30 pre-diameter enlargement, the diameter enlargement tool 60 can be inserted into the heat transfer tube 30 pre-diameter enlargement without limitation to the position of the ribs 64 of the diameter enlargement tool 60. The complexity of the heat transfer tube 30 diameter enlargement operation can accordingly be lessened. Note that the reference numeral 64A in FIG. 6A to FIG. 6C indicates the apex portions of the ribs 64.

As illustrated in FIG. 7A to FIG. 7C, in the diameter enlargement tool 70 of the second modified example, ribs 74 projecting out from the outer peripheral face 52A of the main body 52 extend in a spiral shape from an end portion of the main body 52 on the insertion direction side toward the opposite side to the insertion direction (specifically, in a spiral shape around the outer peripheral face 52A of the main body 52). The spiral direction of the ribs 74 is the opposite direction to the roll-up direction of the metal sheet 31 rolled up into a roll shape. Plural of the ribs 74 are provided at uniform separations around the circumferential direction of the main body 52. Note that on insertion of the diameter enlargement tool 70 into the heat transfer tube 30, the metal sheet 31 rolled up into a roll shape is imparted with force from the spiral shaped ribs 74 in the opposite direction to the roll-up direction and is loosened. This enables a reduction in the load required to enlarge the diameter of the heat transfer tube 30. Note that the reference numeral 74A in FIG. 7A to FIG. 7C indicates the apex portions of the ribs 74.

As illustrated in FIG. 8A to FIG. 8C, in the diameter enlargement tool 80 of the third modified example, ribs 84 projecting out from the outer peripheral face 52A of the main body 52 extend in straight line shapes from an end portion of the main body 52 on the insertion direction side toward the opposite side to the insertion direction. The width (the length around the circumferential direction of the main body 52) of apex portions 84A of the ribs 84 becomes gradually wider on progression toward the opposite side to the insertion direction of the main body 52. Note that when the diameter enlargement tool 80 is inserted into the heat transfer tube 30 pre-diameter enlargement, narrow-width portions of the apex portions 84A of the ribs 84 contact the tube inner face 30B of the heat transfer tube 30 first, enabling resistance due to deformation of the heat transfer tube 30 to be lowered, and enabling a reduction in the load required for insertion. Wider-width portions of the apex portions 84A then contact the tube outer face 30A of the heat transfer tube 30, enabling substantially uniform enlargement around the circumference of the tube inner face 30B of the heat transfer tube 30.

Second Exemplary Embodiment

FIG. 9 illustrates a heat transfer tube 90 of the heat exchanger 22 manufactured by a heat exchanger manufacturing method of a second exemplary embodiment. Note that in the present exemplary embodiment, configuration similar to that of the first exemplary embodiment is allocated the same reference numerals, and further explanation thereof is omitted.

With the exception of the configuration of the heat transfer tube 90, the heat exchanger 22 of the present exemplary embodiment is of similar configuration to the heat exchanger 20 of the first exemplary embodiment.

As illustrated in FIG. 9, an inner peripheral face (referred to below as the “tube inner face 90B”) of the heat transfer tube 90 is formed with an undulating portion 92. The undulating portion 92 is formed over substantially the entire tube inner face 90B. The heat transfer tube 90 of the present exemplary embodiment is an example of a tube-shaped body of the present invention.

The heat transfer tube 90 is formed by rolling up a metal sheet 31 formed with the undulating portion 92 into a roll shape, and joining at a roll-overlap portion. The heat transfer tube 90 of the present exemplary embodiment is a double-walled rolled tube configured by rolling the metal sheet 31 around twice. In the heat transfer tube 90, part of an inner face 31B of the metal sheet 31 rolled up into a roll shape configures the tube inner face 90B, and part of an outer face 31A of the metal sheet 31 rolled up into a roll shape configures a tube outer face 90A. Other than being formed with the undulating portion 92, the metal sheet 31 is of similar configuration to the metal sheet 31 of the first exemplary embodiment.

As illustrated in FIG. 9, the undulating portion 92 is configured by grooves 92A indented toward the radial direction outside of the heat transfer tube 90, formed at intervals around the circumferential direction of the heat transfer tube 90, and extending in a direction intersecting with the axial direction of the heat transfer tube 90 (a direction at an angle in the present exemplary embodiment), and by ridges 92B that are formed between adjacent grooves 92A to form projections toward the radial direction inside of the heat transfer tube 90. Note that the undulating portion of the present invention is not limited to such a configuration. For example, an undulating portion may be configured by forming plural projections and plural recesses on the tube inner face 90B.

Next, explanation follows regarding a manufacturing method of the heat exchanger 22 of the present exemplary embodiment.

Forming Process

First, the flat plate shaped metal sheet 31 is prepared with the covering member affixed to the core, and the undulating portion 92 is formed to one face of the metal sheet 31 (the face formed by the core). Note that the undulating portion 92 is formed to the one face of the metal sheet 31 in a range corresponding to the tube inner face 90B.

Next, the metal sheet 31 formed on the one face with the undulating portion 92 is rolled up into a roll shape with the undulating portion 92 on the inside to form the heat transfer tube 90 that is an example of a tube-shaped body (see FIG. 10).

Next, as illustrated in FIG. 10 and FIG. 11, the diameter enlargement tool 50 is used to perform a diameter enlargement process similar to that of the first exemplary embodiment, thereby enlarging the diameter of the heat transfer tube 90.

A joining process similar to that of the first exemplary embodiment is performed in order to form the heat exchanger 22 of the present exemplary embodiment.

Explanation follows regarding operation and advantageous effects of the manufacturing method of the heat exchanger 22 of the present exemplary embodiment.

In the manufacturing method of the heat exchanger 22, the metal sheet 31 is rolled up into a roll shape, with the undulating portion 92 formed to the one face on the inside, thereby forming the heat transfer tube 90 with the undulating portion 92 formed at the tube inner face 90B. Forming the undulating portion 92 in this manner increases the surface area of the tube inner face 90B of the heat transfer tube 90, raising the heat transfer efficiency between the heat transfer tube 90 and the fluid passing through inside the heat transfer tube 90.

Note that since the manufacturing method of the heat exchanger 22 enables a reduction in the load required to enlarge the diameter of the heat transfer tube 90, similarly to in the first exemplary embodiment, deformation (squashing deformation) of the undulating portion 92 formed to the tube inner face 90B can be suppressed when using the diameter enlargement tool 50 to enlarge the diameter of the heat transfer tube 90. Heat transfer efficiency between the heat transfer tube 90 and the fluid passing through inside the heat transfer tube 90 can accordingly be secured.

In the first exemplary embodiment, the stepped portion 32 is formed to the metal sheet 31 during the diameter enlargement process, however the present invention is not limited to such a configuration. For example, the stepped portion 32 may be formed to the metal sheet 31 in advance, prior to the diameter enlargement process. Note that such a configuration, in which the stepped portion 32 is formed to the metal sheet 31 in advance prior to the diameter enlargement process, may also be applied to the second exemplary embodiment.

In the first exemplary embodiment, the metal sheet 31 is a clad sheet configured by the core and the covering member, however the present invention is not limited thereto, and the metal sheet 31 may be a metal sheet configured by the core alone. In such cases, configuration may be made such that molten joining material (brazing filler) is injected into a gap at the roll-overlap portion of the metal sheet 31 of the heat transfer tube 30 after diameter enlargement to join together the roll-overlap portion of the metal sheet 31. Moreover, one or both faces of the fins 40 may be formed from an aluminum alloy (brazing filler), and heated together with the heat transfer tube 30 after diameter enlargement such that the roll-overlap portion of the metal sheet 31 is joined by the melted aluminum alloy. Such a configuration may also be applied to the second exemplary embodiment.

In the first exemplary embodiment, the heat transfer tube 30 is a double-walled rolled tube configured by rolling the metal sheet 31 around twice, however the present invention is not limited to such a configuration, and the metal sheet 31 may be rolled around more than twice to configure a multi-ply rolled tube. Such a configuration may also be applied to the heat transfer tube 90 of the second exemplary embodiment.

Explanation has been given above regarding exemplary embodiments of the present invention, however these exemplary embodiments are merely examples, and various modifications may be implemented within a range not departing from the spirit of the present invention. Obviously, the scope of rights encompassed by the present invention is not limited by these exemplary embodiments.

The disclosure of Japanese Patent Application No. 2014-014650, filed on Jan. 29, 2014, is incorporated in its entirety by reference herein.

All cited documents, patent applications and technical standards mentioned in the present specification are incorporated by reference in the present specification to the same extent as if the individual cited document, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A heat exchanger manufacturing method, comprising:

rolling a metal sheet into a roll shape to form a tube-shaped body;

inserting the tube-shaped body through a through hole formed at a metal fin, and loosening the metal sheet that has been rolled into a roll shape to enlarge the diameter of the tube-shaped body and place an outer peripheral face of the tube-shaped body in contact with a hole wall of the through hole; and

after enlarging the diameter, joining together a roll-overlap portion of the metal sheet that has been rolled into a roll shape.

2. The heat exchanger manufacturing method of claim 1, wherein, in the enlarging of the diameter, inserting a diameter enlargement tool, with an external diameter that is larger than an internal diameter of the tube-shaped body prior to diameter enlargement, inside the tube-shaped body to forcibly loosen the metal sheet that has been rolled into a roll shape and enlarge the diameter of the tube-shaped body.

3. The heat exchanger manufacturing method of claim 2, wherein the metal sheet has an undulating portion formed on one sheet face and, in the forming of the tube-shaped body, rolling the metal sheet into a roll shape to form the tube-shaped body with the undulating portion at an inner side thereof.

4. The heat exchanger manufacturing method of claim 2, comprising configuring the metal sheet by aluminum.

5. The heat exchanger manufacturing method of claim 2, wherein the diameter enlargement tool comprises:

a circular column-shaped main body that is inserted inside the tube-shaped body;

ribs that are provided at intervals in a circumferential direction around an outer peripheral face of the main body, that project outwardly from the main body outer peripheral face, that extend from an end portion of the main body at an insertion direction side toward an opposite side to the insertion direction, and that contact an inner peripheral face of the tube-shaped body; and

inclined portions that are formed at insertion direction leading end portions of the ribs, and that have a projection height from the main body outer peripheral face that gradually increases toward the opposite side to the insertion direction.

6. The heat exchanger manufacturing method of claim 5, wherein the ribs extend in a spiral shape toward the opposite side of the main body to the insertion direction, with the direction of the spiral being set as an opposite direction to a roll-up direction of the metal sheet that has been rolled into a roll shape.

7. The heat exchanger manufacturing method of claim 5, wherein:

the ribs extend in straight line shapes toward the opposite side of the main body to the insertion direction; and

an interval between respective contact portions, at which two of the ribs disposed on either side of a peripheral inside edge portion of the metal sheet that has been rolled into a roll shape contact the inner peripheral face of the tube-shaped body, widens toward the opposite side to the insertion direction.

8. A diameter enlargement tool to enlarge the diameter of a tube-shaped body formed by rolling a metal sheet into a roll shape, the diameter enlargement tool comprising:

a circular column-shaped main body that is inserted inside the tube-shaped body;

ribs that are provided at intervals in a circumferential direction around an outer peripheral face of the main body, that project outward from the main body outer peripheral face, that extend from an end portion of the main body at an insertion direction side toward an opposite side to the insertion direction, and that contact an inner peripheral face of the tube-shaped body; and

inclined portions that are formed at insertion direction leading end portions of the ribs, and that have a projection height from the main body outer peripheral face that gradually increases toward the opposite side to the insertion direction, wherein

an external diameter of the diameter enlargement tool is larger than an internal diameter of the tube-shaped body.