CN113993650A

CN113993650A - Method for manufacturing heat exchanger

Info

Publication number: CN113993650A
Application number: CN201980097737.0A
Authority: CN
Inventors: 堀久司; 濑尾伸城
Original assignee: Nippon Light Metal Co Ltd
Current assignee: Nippon Light Metal Co Ltd
Priority date: 2019-06-28
Filing date: 2019-11-19
Publication date: 2022-01-28
Anticipated expiration: 2039-11-19
Also published as: CN113993650B; JP2021006349A; JP7127618B2; WO2020261597A1

Abstract

The method comprises a primary welding step in which only a stirring pin (F2) of a rotating tool (F) is inserted into an outer peripheral surface (11F) of the perforated pipe (2), the rotating tool is rotated by one rotation around the outer peripheral surface (11F) of the perforated pipe (2) along a set movement path (L1) set on the perforated pipe (2) side with respect to a connection part (J1) by a predetermined depth while allowing the second aluminum alloy to flow into a gap in a state where the outer peripheral surface of the stirring pin (F2) and a step inclined surface (23b) of a lid body (3) are brought into slight contact, and the connection part (J1) is subjected to friction stirring, wherein after the rotating only stirring pin (F2) is inserted to a start position (SP1) set on the perforated pipe (2) side with respect to the set movement path (L1), a rotation center axis (Z) of the rotating tool (F) is moved to a position overlapping the set movement path (L1), while slowly pushing the stirring pin (F2) to the predetermined depth.

Description

Method for manufacturing heat exchanger

Technical Field

The present invention relates to a method for manufacturing a heat exchanger.

Background

For example, patent document 1 discloses a method of manufacturing a heat exchanger in which a perforated pipe having a plurality of holes arranged in parallel and a closing member for closing the openings of the perforated pipe are joined by friction stirring. Fig. 8 is a sectional view showing a conventional method for manufacturing a heat exchanger.

In a conventional method for manufacturing a heat exchanger, after an extruded multi-hole tube 101 made of an aluminum alloy including a plurality of fins 110 is butted against a stepped portion 103 formed on the outer periphery of a lid body 102 to form a butted portion J10, a rotary tool G is used to friction stir bond the butted portion J10. The step portion 103 is composed of a step bottom surface 103a and a step side surface 103 b. The abutting portion J10 is configured such that the end face 101a of the extruded multi-hole tube 101 abuts against the stepped bottom surface 103a of the lid 102. The rotary tool G includes a shaft shoulder G1 and a stirring pin G2 depending from the shaft shoulder G1. In the friction stirring step, the rotational center axis Z of the rotating stirring pin G2 is overlapped with the butting portion J10 and moved relatively.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2016-74016

Disclosure of Invention

Technical problem to be solved by the invention

Here, there are cases where a member having a relatively simple shape, such as the extruded multi-hole tube 101, is formed of an expanded material of 1000 series aluminum alloy, and the lid body 102 is formed of a cast material of 4000 series aluminum alloy, for example. In this way, there is a case where members made of different types of aluminum alloys are joined to each other to manufacture a heat exchanger. In this case, since the hardness of the lid body 102 is generally higher than that of the extruded porous tube 101, when the friction stir welding is performed as shown in fig. 8, the material resistance received by the stirring pin G2 from the lid body 102 side is higher than the material resistance received from the extruded porous tube 101 side. Therefore, it is difficult to stir different types of materials with high balance by the stirring pin G2 of the rotary tool G, and there is a problem that a void defect occurs in a plasticized region after joining, and the joining strength is lowered.

As shown in fig. 8, when the stirring pin G2 is inserted into the butting portion J10, the stirring pin G2 is pushed in the plumb direction to a predetermined depth, and therefore the frictional heat at the start position of the friction stirring becomes excessively large. Therefore, at this start position, there is a problem that metal on the lid 102 side is likely to be mixed into the extruded multi-hole pipe 101 side, which causes poor bonding.

On the other hand, when the stirring pin G2 is pulled out and disengaged from the butting portion J10, the stirring pin G2 is pulled out in the plumb direction, and therefore the frictional heat at the end position of the friction stirring becomes excessive. Therefore, at this end position, there is a problem that the metal on the lid 102 side is likely to be mixed into the extruded multi-hole pipe 101 side, which causes a poor connection.

From such a viewpoint, an object of the present invention is to provide a method for manufacturing a heat exchanger capable of desirably joining aluminum alloys different in material type.

Technical scheme for solving technical problem

In order to solve the above-described problems, the present invention provides a method of manufacturing a heat exchanger including a perforated tube having fins inside and a lid body closing an opening of the perforated tube, the perforated tube being joined to the lid body by friction stirring, the lid body including a bottom portion and a peripheral wall portion rising from a peripheral edge of the bottom portion, the peripheral wall portion having a peripheral wall step portion formed on an outer peripheral edge thereof, the peripheral wall step portion including a step side surface and a step inclined surface inclined so as to approach the bottom portion side as it goes outward from the step side surface, the perforated tube having a fitting portion at an end portion thereof for fitting with the peripheral wall portion without forming the fins, the perforated tube being formed of a second aluminum alloy, the lid body being formed of a first aluminum alloy, the first aluminum alloy is a material having a hardness greater than that of the second aluminum alloy, and a rotating tool used for friction stirring includes a stirring pin that is tapered toward a tip end side, and the method for manufacturing the heat exchanger includes: a butt joint step of forming a gap having a V-shaped cross section at a butt joint portion by inserting the peripheral wall portion of the lid body into the fitting portion of the porous extrusion pipe, so that an inner peripheral surface of the porous extrusion pipe overlaps a step side surface of the lid body, and so that an end surface of the porous extrusion pipe is butted against the step inclined surface of the lid body; and a primary welding step of inserting only a stirring pin of the rotating tool into an outer peripheral surface of the perforated pipe, and rotating the rotating tool around the outer peripheral surface of the perforated pipe by a predetermined depth along a predetermined movement path set on the perforated pipe side with respect to the butting portion while allowing the second aluminum alloy to flow into the gap in a state where the outer peripheral surface of the stirring pin and the step inclined surface of the lid body are in slight contact, thereby performing friction stirring on the butting portion, wherein in the primary welding step, after the rotating stirring pin is inserted to a start position set on the perforated pipe side with respect to the set movement path, a rotation center axis of the rotating tool is moved to a position overlapping the set movement path, while slowly pushing the stirring pin to the predetermined depth.

Further, the present invention provides a method of manufacturing a heat exchanger including a multi-hole extrusion pipe having fins inside and a lid body closing an opening of the multi-hole extrusion pipe, the multi-hole extrusion pipe being joined to the lid body by friction stirring, wherein the lid body includes a bottom portion and a peripheral wall portion rising from a peripheral edge of the bottom portion, a peripheral wall step portion is formed on an outer peripheral edge of the peripheral wall portion, the peripheral wall step portion includes a step side surface and a step inclined surface inclined so as to approach the bottom portion side from the step side surface toward an outer side, the multi-hole extrusion pipe includes a fitting portion at an end portion, the fitting portion does not have the fins and is fitted to the peripheral wall portion, the multi-hole extrusion pipe is formed of a second aluminum alloy, the lid body is formed of a first aluminum alloy, which is a material type having hardness greater than that of the second aluminum alloy, a method for manufacturing a heat exchanger, the method including: a butt joint step of forming a gap having a V-shaped cross section at a butt joint portion by inserting the peripheral wall portion of the lid body into the fitting portion of the porous extrusion pipe, so that an inner peripheral surface of the porous extrusion pipe overlaps a step side surface of the lid body, and so that an end surface of the porous extrusion pipe is butted against the step inclined surface of the lid body; and a primary welding step of inserting only a stirring pin of the rotating tool into an outer peripheral surface of the perforated pipe, and rotating the rotating tool around the outer peripheral surface of the perforated pipe by a predetermined depth along a predetermined movement path set on the perforated pipe side of the butting portion while allowing the second aluminum alloy to flow into the gap in a state where the outer peripheral surface of the stirring pin and the step inclined surface of the lid body are slightly in contact with each other, thereby friction-stirring the butting portion.

According to the above production method, the second aluminum alloy mainly on the side of the multi-hole extrusion pipe in the butt joint portion is stirred by frictional heat between the lid body and the multi-hole extrusion pipe to be plastically fluidized, whereby the lid body and the multi-hole extrusion pipe can be joined to each other at the butt joint portion. Further, since the outer peripheral surface of the stirring pin is kept in slight contact with the lid body, the mixing of the first aluminum alloy into the perforated pipe from the lid body can be reduced as much as possible. Thus, the second aluminum alloy is friction-stirred mainly on the side from which the multi-hole pipe is extruded at the butted portion, and therefore, a decrease in the joining strength can be suppressed. Further, by slowly pushing the stirring pin to a predetermined depth while moving the rotary tool, it is possible to prevent the frictional heat from being locally excessive. This prevents the first aluminum alloy of the lid from being mixed into the perforated pipe in the set movement path.

In the primary welding step, it is preferable that the stirring pin is rotated at a predetermined rotation speed to perform friction stirring, and when the stirring pin is inserted in the primary welding step, the stirring pin is inserted while being rotated at a speed higher than the predetermined rotation speed, and the stirring pin is moved to the set movement path while the rotation speed is gradually decreased.

According to the above manufacturing method, friction stir welding can be more preferably performed.

Further, the present invention provides a method of manufacturing a heat exchanger including a multi-hole extrusion pipe having fins inside and a lid body closing an opening of the multi-hole extrusion pipe, the multi-hole extrusion pipe being joined to the lid body by friction stirring, wherein the lid body includes a bottom portion and a peripheral wall portion rising from a peripheral edge of the bottom portion, a peripheral wall step portion is formed on an outer peripheral edge of the peripheral wall portion, the peripheral wall step portion includes a step side surface and a step inclined surface inclined so as to approach the bottom portion side from the step side surface toward an outer side, the multi-hole extrusion pipe includes a fitting portion at an end portion, the fitting portion does not have the fins and is fitted to the peripheral wall portion, the multi-hole extrusion pipe is formed of a second aluminum alloy, the lid body is formed of a first aluminum alloy, which is a material type having hardness greater than that of the second aluminum alloy, a method for manufacturing a heat exchanger, the method including: a butt joint step of forming a gap having a V-shaped cross section at a butt joint portion by inserting the peripheral wall portion of the lid body into the fitting portion of the porous extrusion pipe, so that an inner peripheral surface of the porous extrusion pipe overlaps a step side surface of the lid body, and so that an end surface of the porous extrusion pipe is butted against the step inclined surface of the lid body; and a primary welding step of inserting only a stirring pin of the rotating tool into an outer peripheral surface of the perforated pipe, and rotating the rotating tool around the outer peripheral surface of the perforated pipe by a predetermined depth along a predetermined movement path set on the perforated pipe side with respect to the butting portion while allowing the second aluminum alloy to flow into the gap in a state where the outer peripheral surface of the stirring pin and the step inclined surface of the lid body are in slight contact, thereby friction-stirring the butting portion, wherein in the primary welding step, an end position is set on the perforated pipe side with respect to the set movement path, and after the friction-stirring welding of the butting portion, the stirring pin is slowly pulled out while moving the rotating tool to the end position, thereby disengaging the rotary tool from the expression perforated tube at the end position.

Further, the present invention provides a method of manufacturing a heat exchanger including a multi-hole extrusion pipe having fins inside and a lid body closing an opening of the multi-hole extrusion pipe, the multi-hole extrusion pipe being joined to the lid body by friction stirring, wherein the lid body includes a bottom portion and a peripheral wall portion rising from a peripheral edge of the bottom portion, a peripheral wall step portion is formed on an outer peripheral edge of the peripheral wall portion, the peripheral wall step portion includes a step side surface and a step inclined surface inclined so as to approach the bottom portion side from the step side surface toward an outer side, the multi-hole extrusion pipe includes a fitting portion at an end portion, the fitting portion does not have the fins and is fitted to the peripheral wall portion, the multi-hole extrusion pipe is formed of a second aluminum alloy, the lid body is formed of a first aluminum alloy, which is a material type having hardness greater than that of the second aluminum alloy, a method for manufacturing a heat exchanger, the method including: a butt joint step of forming a gap having a V-shaped cross section at a butt joint portion by inserting the peripheral wall portion of the lid body into the fitting portion of the porous extrusion pipe, so that an inner peripheral surface of the porous extrusion pipe overlaps a step side surface of the lid body, and so that an end surface of the porous extrusion pipe is butted against the step inclined surface of the lid body; and a primary joining step of inserting only the stirring pin of the rotating tool into the outer peripheral surface of the extruded porous pipe, the friction stirring pin is configured to cause the second aluminum alloy to flow into the gap while the outer peripheral surface of the stirring pin and the step inclined surface of the lid body are in slight contact with each other, and to rotate the rotating tool around the outer peripheral surface of the perforated pipe by a predetermined depth along a predetermined movement path set on the perforated pipe side of the butted portion to perform friction stirring on the butted portion, in the primary welding step, an end position is set on the set movement path, and after the friction stir welding of the butting portion, and slowly pulling out the stirring pin while moving the rotating tool to the end position, thereby detaching the rotating tool from the perforated extrusion pipe at the end position.

According to the above production method, the second aluminum alloy mainly on the side of the multi-hole extrusion pipe in the butt joint portion is stirred by frictional heat between the lid body and the multi-hole extrusion pipe to be plastically fluidized, whereby the lid body and the multi-hole extrusion pipe can be joined to each other at the butt joint portion. Further, since the outer peripheral surface of the stirring pin is kept in slight contact with the lid body, the mixing of the first aluminum alloy into the perforated pipe from the lid body can be reduced as much as possible. Thus, the second aluminum alloy is friction-stirred mainly on the side from which the multi-hole pipe is extruded at the butted portion, and therefore, a decrease in the joining strength can be suppressed. Further, by slowly pulling out the stirring pin while moving the rotary tool, it is possible to prevent the frictional heat from locally becoming excessively large. This prevents the first aluminum alloy of the lid from being mixed into the perforated pipe in the set movement path.

Preferably, in the primary welding step, the stirring pin is rotated at a predetermined rotation speed to perform friction stirring, and when the stirring pin is disengaged in the primary welding step, the stirring pin is moved to an end position while gradually increasing the rotation speed from the predetermined rotation speed.

In the butt joint step, the perforated extrusion pipe and the lid body are preferably formed so that an outer peripheral surface of the perforated extrusion pipe is located outside an outer peripheral surface of the lid body.

According to the manufacturing method, insufficient metal at the joint portion can be prevented.

Preferably, the rotation direction and the travel direction of the rotary tool are set so that the docking portion side is an advancing side.

According to the above manufacturing method, friction stirring on the butt joint portion side can be promoted, and joining can be performed more desirably.

In the primary welding step, it is preferable that the tip end of the stirring pin is rotated once around the outer peripheral surface of the perforated tube while passing through the step side surface of the lid body, and the butted portion is friction-stirred.

According to the above manufacturing method, the lid body and the extruded porous pipe can be more desirably joined.

Preferably, the first aluminum alloy is formed of a cast material, and the second aluminum alloy is formed of an extended material.

Effects of the invention

According to the method of manufacturing a heat exchanger of the present invention, aluminum alloys of different material types can be preferably joined.

Drawings

Fig. 1 is an exploded perspective view showing a heat exchanger according to a first embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a butting step in the method for manufacturing a heat exchanger according to the first embodiment.

Fig. 3 is a schematic diagram showing a start position of a main bonding step in the method for manufacturing a heat exchanger according to the first embodiment.

Fig. 4 is a sectional view showing a main joining step in the method for manufacturing a heat exchanger according to the first embodiment.

Fig. 5 is a schematic view showing the end position of the main joining step in the method for manufacturing a heat exchanger according to the first embodiment.

Fig. 6 is a schematic view showing a start position of a main bonding step in a method of manufacturing a heat exchanger according to a second embodiment of the present invention.

Fig. 7 is a schematic view showing the end position of the main joining step in the method for manufacturing a heat exchanger according to the second embodiment of the present invention.

Fig. 8 is a sectional view showing a conventional method for manufacturing a heat exchanger.

Detailed Description

[ first embodiment ]

Embodiments of the present invention will be described with reference to the accompanying drawings as appropriate. As shown in fig. 1, a heat exchanger 1 according to the first embodiment includes a multi-hole extrusion pipe 2 and covers 3 and 3 disposed at both ends of the multi-hole extrusion pipe 2. The heat exchanger 1 is a device for cooling the arranged heating elements while allowing a fluid to flow therein. The extruded porous pipe 2 and the

caps

3 and 3 are integrated by friction stir welding.

The extruded porous tube 2 is mainly composed of a main body 11 and a plurality of fins 12. The extruded multi-hole pipe 2 is formed to mainly contain the second aluminum alloy in the present embodiment. The second aluminum alloy is formed of, for example, JISA1050, a1100, a6063 or other aluminum alloy wrought material. The extrudate 2 is an extrudate formed from a second aluminum alloy.

The main body 11 has a cylindrical shape. The

side portions

11a, 11b of the main body 11 are curved so as to protrude outward (outward in the width direction of the main body 11). The

substrate portions

11c and 11d of the main body 11 are flat and parallel to each other. That is, the body portion 11 has an oblong cross section. The fins 12 are perpendicular to the

base plate portions

11c and 11 d. The fins 12 extend in the extrusion direction of the main body 11 and are formed in parallel with each other. A hole 13 having a rectangular cross section through which a fluid flows is formed between adjacent fins 12.

Fitting portions 14 in which the fins 12 are not formed are formed in openings at both ends of the extruded multi-hole tube 2. The fitting portion 14 is a portion into which a peripheral wall portion 22 of the lid body 3 described later is inserted. The fitting portion 14 is formed by cutting both ends of the fin 12. The shape of the extruded porous pipe 2 is not limited to the above shape. For example, the extruded perforated tube 2 has a circular, oval or square cross-section (a cross-section perpendicular to the extrusion direction).

The

covers

3 and 3 are members for closing the openings at both ends of the perforated tube 2. The

covers

3 and 3 are respectively in the same shape. The lid 3 has a bottom 21 and a peripheral wall 22. The bottom 21 is a plate-like member having an oblong shape. The bottom portion 21 is formed in a shape substantially identical to the shape of the main body portion 11 of the perforated pipe 2 so as to close the opening of the perforated pipe 2. The peripheral wall 22 is a portion vertically rising from the peripheral edge of the bottom portion 21. The peripheral wall portion 22 is formed in an oval frame shape along the shape of the bottom portion 21. A recessed header passage 24 is formed by the bottom portion 21 and the peripheral wall portion 22.

The lid 3 is not particularly limited as long as it is a metal capable of friction stirring, but in the present embodiment, it is formed to mainly contain the first aluminum alloy. The first aluminum alloy is a material having a hardness greater than that of the second aluminum alloy. The first aluminum alloy is cast using an aluminum alloy such as JISH5302ADC12 (Al-Si-Cu series), for example.

As shown in fig. 2, a peripheral wall step portion 23 is formed on the outer periphery of the peripheral wall portion 22, and the peripheral wall step portion 23 includes a step side surface 23a and a step inclined surface 23b rising from the step side surface 23 a. The peripheral wall layer difference portion 23 is formed over the entire circumferential direction. The step side 23a is parallel to the extrusion direction. The step inclined surface 23b is inclined so as to approach the bottom portion 21 from the step side surface 23a toward the outside (the outside in the width direction of the main body portion 11). In other words, the level difference inclined surface 23b is inclined so as to be away from the main body portion 11 as it goes outward. The inclination angle β of the step inclined surface 23b is a constant inclination angle.

The outer peripheral surface 11f of the perforated pipe 2 and the outer peripheral surface 22b of the peripheral wall portion 22 may be flush with each other, but in the present embodiment, the perforated pipe 2 and the lid body 3 are set such that the outer peripheral surface 11f of the perforated pipe 2 is located outside the outer peripheral surface 22b of the peripheral wall portion 22 after the butting step described below. In other words, the height (thickness) of the end surface 11e of the extruded porous pipe 2 is set to be larger than the height of the stepped inclined surface 23 b.

Next, a method for manufacturing the heat exchanger of the present embodiment will be described. In the method of manufacturing a heat exchanger according to the present embodiment, a preparation step, a butt joint step, and a main joining step are performed.

The preparation step is a step of preparing to press out the porous tube 2 and the lid 3. The extruded porous pipe 2 and the lid body 3 are not particularly limited in terms of the manufacturing method, but the extruded porous pipe 2 is formed by, for example, extrusion molding. The cover 3 is molded by, for example, die casting.

As shown in fig. 2, the butt joint step is a step of butting the lid body 3 and the extruded porous pipe 2. In the abutting step, the fitting portion 14 of the discharge multi-hole tube 2 is fitted to the peripheral wall portion 22 of the lid body 3. Thus, the step inclined surface 23b of the lid 3 is abutted against the end surface 11e of the perforated pipe 2 to form an abutment J1, and the step side surface 23a of the lid 3 is overlapped against the inner peripheral surface 11g of the perforated pipe 2 to form an abutment J2. The end surface 22a of the peripheral wall 22 is in contact with the end surface 12a of the fin 12 or faces the end surface 12a with a slight gap therebetween. The abutting portions J1 and J2 are formed in the circumferential direction. A gap having a V-shaped cross section is formed in the abutting portion J1.

As shown in fig. 3 and 4, the main joining step is a step of friction stir joining the abutting portion J1 using the rotary tool F. First, the "set movement path L1" (one-dot chain line) is set at a position away from the lid 3 with respect to the abutting portion J1. The set movement path L1 is a movement path of the rotary tool F necessary for joining the joining portion J1 in the main joining process described later. Details about the setting movement path L1 will be described later.

As shown in fig. 4, the rotary tool F includes a coupling portion F1 and a stirring pin F2. The rotary tool F is formed of, for example, tool steel. The connection portion F1 is connected to a rotation shaft of a friction stir device (not shown). The coupling portion F1 has a cylindrical shape and is formed with a screw hole (not shown) to which a bolt is fastened.

The stirring pin F2 is suspended from the coupling portion F1 and is coaxial with the coupling portion F1. The stirring pin F2 becomes tapered as it goes away from the joint F1. The inclination angle α of the stirring pin F2 with respect to the rotation center axis Z is the same as the inclination angle β (fig. 2) of the level difference inclined surface 23b with respect to the plumb surface. The stirring pin F2 includes a flat surface F3 at its front end.

A spiral groove is engraved on the outer peripheral surface of the stirring pin F2. In the present embodiment, since the rotary tool F is rotated rightward, the spiral groove is formed to be wound leftward from the base end toward the tip end. In other words, the spiral groove is formed to be wound leftward when viewed from above when the spiral groove is drawn from the base end toward the tip end.

Further, when the rotary tool F is rotated to the left, the spiral groove is preferably formed to be wound to the right from the base end toward the tip end. In other words, the spiral groove in this case is formed so as to be wound rightward when viewed from above when the spiral groove is drawn from the base end toward the tip end. By setting the spiral groove in the above manner, the metal plastically fluidized at the time of friction stirring is guided toward the leading end side of the stirring pin F2 by the spiral groove. This can reduce the amount of metal that overflows to the outside of the joined metal members (the extruded porous pipe 2 and the lid body 3). The rotary tool F may be attached to a robot arm having a rotary drive unit such as a spindle unit provided at the tip thereof, for example.

As shown in fig. 3, in the primary welding step, friction stir welding is continuously performed in three sections, namely, a press-in section from the start position SP1 to the intermediate point S1, a primary section rotated one revolution from the intermediate point S1 on the set movement path L1 to the intermediate point S2, and a disengagement section from the intermediate point S2 to the end position EP 1. The intermediate points S1 and S2 are set on the set movement path L1. The start position SP1 is set in the body 11 of the discharge multi-hole tube 2 at a position distant from the lid 3 with respect to the set movement path L1. In the present embodiment, the start position SP1 is set at a position where an angle formed by a line segment connecting the start position SP1 and the intermediate point S1 and the set movement path L1 is an obtuse angle.

In the press-fitting section of the primary welding step, friction stirring is performed from the start position SP1 to the intermediate point S1. In the press-fit section, the stirring pin F2 rotating rightward is inserted to the start position SP1 while the rotation center axis Z is perpendicular to the outer peripheral surface 11F of the main body 11, and moves relatively to the intermediate point S1. At this time, the stirring pin F2 is slowly pushed in to reach a predetermined "predetermined depth" at least before reaching the intermediate point S1. That is, the rotary tool F is gradually lowered while moving on the set movement path L1 without being stopped at one position. After the rotating tool F reaches the intermediate point S1, the transition to the main section is made.

In the main section, the rotary tool F is rotated once along the set movement path L1 as shown in fig. 4. In the main section, the outer peripheral surface of the stirring pin F2 is set to be parallel to the step inclined surface 23b when reaching the intermediate point S1. When reaching the intermediate point S1, the outer peripheral surface of the stirring pin F2 is set to slightly contact the level difference inclined surface 23 b. The rotation center axis Z of the rotary tool F is set to be perpendicular to the outer peripheral surface 11F of the main body 11, and the rotary tool F is relatively moved along the butting portion J1 while maintaining the rotation center axis Z and the outer peripheral surface.

The contact amount (offset amount) N between the outer peripheral surface of the stirring pin F2 and the level difference inclined surface 23b is set to, for example, 0 < N.ltoreq.1.0 mm, preferably 0 < N.ltoreq.0.85 mm, and more preferably 0 < N.ltoreq.0.65 mm.

As shown in fig. 4, the set movement path L1 represents a trajectory passing through the center of the flat surface F3. That is, the movement path L1 is set so that the step inclined surface 23b is parallel to the outer peripheral surface of the stirring pin F2 in the circumferential direction of the butting portion J1 while slightly contacting the outer peripheral surface. In the main section, when the rotary tool F is viewed from above, the rotary tool F is moved so that the center of the flat surface F3 overlaps the set movement path L1. In addition, the "predetermined depth" of the stirring pin F2 may be appropriately set, but in the present embodiment, the flat surface F3 of the rotary tool F is inserted to a position where it passes through the step side surface 23 a. This also ensures the engagement of the abutting portion J2.

If the outer peripheral surface of the stirring pin F2 is set so as not to contact the level difference inclined surface 23b, the joining strength of the butting portion J1 becomes low. On the other hand, if the contact amount N of the stirring pin F2 and the step inclined surface 23b is larger than 1.0mm, the first aluminum alloy of the lid body 3 may be mixed into the extrusion multi-hole pipe 2 in a large amount, which may cause poor joining.

As shown in fig. 5, after the stirring pin F2 reaches the intermediate point S2 after the rotating tool F is rotated once, the operation transitions to the disengagement section. In the disengagement section, the stirring pin F2 is slowly pulled out (raised) from the middle point S2 toward the end position EP1, and the stirring pin F2 is disengaged from the extrusion multi-hole tube 21 at the end position EP 1. That is, the rotary tool F is slowly pulled out while moving to the end position EP1 without being stopped at one position. The end position EP1 is set at a position where an angle formed by a line segment connecting the end position EP1 and the intermediate point S2 and the set movement path L1 is obtuse. A plasticized region W1 is formed on the moving locus of the rotary tool F. After the completion of the friction stir welding of the perforated pipe 2 and the lid body 3 on the one end side as described above, the friction stir welding of the perforated pipe 2 and the lid body 3 on the other end side is performed in the same manner.

According to the method of manufacturing the heat exchanger of the present embodiment described above, the frictional heat between the multi-hole extrusion pipe 2 and the stirring pin F2 stirs and plastically fluidizes the second aluminum alloy of the abutting portion J1, mainly on the multi-hole extrusion pipe 2 side, so that the end face 11e of the multi-hole extrusion pipe 2 and the step inclined surface 23b of the lid body 3 can be joined to each other at the abutting portion J1.

Further, since the outer peripheral surface of the stirring pin F2 is kept in slight contact with the stepped inclined surface 23b, the mixing of the first aluminum alloy into the extruded multi-hole pipe 2 from the lid body 3 can be reduced as much as possible. Thus, the friction stirring is performed mainly on the second aluminum alloy on the side from which the multi-hole pipe 2 is extruded at the butting portion J1, and therefore, the reduction of the joining strength can be suppressed. That is, in the main joining step, the material resistance of the stirring pin F2 on one side and the other side with respect to the rotation center axis Z of the stirring pin F2 can be made as small as possible. Further, since the outer peripheral surface of the stirring pin F2 is set to be parallel to the step inclined surface 23b of the lid body 3, the friction stirring can be performed on the plastic fluidizing material with high balance, and the reduction of the joining strength can be suppressed.

In the press-fitting section of the main joining process, the stirring pin F2 is slowly press-fitted to a predetermined depth while the rotary tool F is moved from the start position SP1 to a position overlapping the set movement path L1, and the rotary tool F is prevented from stopping on the set movement path L1 and causing excessive frictional heat.

Similarly, in the disengagement section of the main joining process, the stirring pin F2 is gradually pulled out from the predetermined depth and disengaged while the rotary tool F is moved from the set movement path L1 to the end position EP1, and the rotary tool F can be prevented from stopping on the set movement path L1 and causing excessive frictional heat.

This prevents excessive frictional heat from being generated in the set movement path L1, and prevents the first aluminum alloy from excessively mixing into the multi-hole extrusion pipe 2 from the lid body 3 and causing poor joining.

In the main joining step, the positions of the start position SP1 and the end position EP1 may be appropriately set, but by setting the angle formed by the start position SP1 and the set movement path L1 and the angle formed by the end position EP1 and the set movement path L1 to an obtuse angle, the rotary tool F can be smoothly transferred to the main zone or the escape zone without decreasing the movement speed of the rotary tool F at the intermediate points S1 and S2. This prevents excessive frictional heat from being generated due to the stopping of the rotary tool F on the set movement path L1 or a decrease in the movement speed. The rotary tool F may be moved from the start position SP1 to the set movement path L1 so that the trajectory of the rotary tool F describes an arc when viewed from above. Similarly, the rotary tool F may be moved from the set movement path L1 to the end position EP1 so that the trajectory of the rotary tool F describes an arc when viewed from above.

In the main joining step of the present embodiment, the rotation direction and the advancing direction of the rotary tool F may be appropriately set, but the rotation direction and the advancing direction of the rotary tool F are set such that the lid body 3 side (the butting portion J1 side) in the plasticized region W1 formed in the movement locus of the rotary tool F is a shear side and the perforated pipe 2 side is a flow side. By setting the lid 3 side to be the shear side, the stirring action of the stirring pin F2 is increased around the butting portion J1, and the extruded porous pipe 2 and the lid 3 can be joined more reliably at the butting portion J1 in anticipation of a temperature rise at the butting portion J1.

The shear side (Advancing side) is a side where the relative speed of the outer periphery of the rotating tool with respect to the engaged portion is a value obtained by adding the magnitude of the moving speed to the magnitude of the tangential speed at the outer periphery of the rotating tool. On the other hand, the flow side (Retreating side) means a side where the relative speed of the rotary tool with respect to the engaged portion becomes low by rotating the rotary tool in the direction opposite to the moving direction of the rotary tool.

Further, the first aluminum alloy of the lid body 3 is a material having a hardness greater than that of the second aluminum alloy extruded out of the perforated pipe 2. This can improve the durability of the heat exchanger 1. Preferably, the first aluminum alloy of the lid body 3 is an aluminum alloy cast material, and the second aluminum alloy of the extruded multi-hole pipe 2 is an aluminum alloy expanded material. By using the first aluminum alloy as a casting material of an Al-Si-Cu series aluminum alloy such as JISH5302ADC12, for example, the castability, strength, machinability, and the like of the lid body 3 can be improved. Further, by making the second aluminum alloy, for example, JISA1000 series or a6000 series, the workability and the thermal conductivity of the extruded porous pipe 2 can be improved.

In the main joining step, the entire circumference of the abutting portion J1 can be joined by friction stir welding, and therefore, the air tightness and water tightness of the heat exchanger can be improved. Further, at the terminal end portion of the main joining process, after the rotary tool F completely passes through the intermediate point S1, it is directed toward the end position EP 1. That is, the air-tightness and the water-tightness can be further improved by overlapping the respective ends of the plasticized region W1 formed by the primary joining process.

In the main joining step, friction stirring is performed with the base end side of the stirring pin F2 of the rotating tool F exposed, and therefore the load acting on the friction stirring device can be reduced. In the present embodiment, after the butting step, the outer peripheral surface 11f of the extruded porous pipe 2 is set to be located outside the outer peripheral surface 22b of the peripheral wall portion 22. This can further prevent the shortage of metal in the butting portion J1 when friction stirring is performed.

Further, by including the header flow path 24 in the lid body 3, the fluid flowing into or out of the hole portion 13 can be collected.

In the primary joining step, the rotation speed of the rotary tool F may be constant or variable. In the press-fitting section of the main joining step, when the rotation speed of the rotary tool F at the start position SP1 is V1 and the rotation speed of the rotary tool F in the main section is V2, V1 > V2 may be set. The rotation speed V2 is a predetermined constant rotation speed on the set movement path L1. That is, at the start position SP1, the rotation speed may be set to be high in advance, and the transition may be made to the actual section while gradually decreasing the rotation speed in the push-in section.

In the disengagement section of the first main joining step, when the rotation speed of the rotary tool F in the main section is V2 and the rotation speed of the rotary tool F at the time of disengagement at the end position EP1 is V3, V3 > V2 may be set. That is, after the transition to the escape section, the rotary tool F may be escaped from the perforated extrusion pipe 2 while gradually raising the rotation speed toward the end position EP 1. When the rotary tool F is pushed into the perforated pipe 2 or when the rotary tool F is separated from the perforated pipe 2, the small pressing force in the pushing-in section or the separating section can be compensated for by the rotational speed by setting as described above, and therefore, friction stirring can be performed desirably.

[ second embodiment ]

Next, a method for manufacturing a heat exchanger according to a second embodiment of the present invention will be described. In the second embodiment, as shown in fig. 6 and 7, the positions of the start position SP1, the intermediate points S1, S2, and the end position EP1 in the main joining process are all set on the set movement path L1, which is different from the first embodiment. In the second embodiment, a description will be given centering on a portion different from the first embodiment.

In the manufacture of the heat exchanger according to the second embodiment, a preparation step, a butt joint step, and a main joining step are performed. The preparation step and the docking step are the same as those in the first embodiment.

In the main joining step, as shown in fig. 6, the start position SP1 is set on the set movement path L1. In the primary joining step, friction stirring is continuously performed in three sections, i.e., a press-in section from the start position SP1 to the intermediate point S1, a primary section from the intermediate point S1 on the set movement path L1 to the intermediate point S2 by one rotation, and a disengagement section from the intermediate point S2 to the end position EP 1.

In the press-in section, as shown in fig. 6, friction stirring is performed from the start position SP1 on the set movement path to the intermediate point S1. In the press-fitting section, the stirring pin F2 rotated to the right is inserted to the start position SP1 while the rotation center axis Z is perpendicular to the outer peripheral surface 11F of the multi-hole extrusion pipe 2, and is relatively moved to the intermediate point S1. At this time, the stirring pin F2 is slowly pushed in to reach a predetermined "predetermined depth" at least before reaching the intermediate point S1.

In the press-fitting section, when the rotary tool F is moved and reaches the intermediate point S1, the outer peripheral surface of the stirring pin F2 is set to be parallel to the step inclined surface 23b, and the outer peripheral surface of the stirring pin F2 is set to be slightly in contact with the step inclined surface 23 b. Then, the state is maintained, and the process shifts to the friction stir welding in the main zone. The contact amount (offset amount) N between the outer peripheral surface of the stirring pin F2 and the level difference inclined surface 23b and the setting of the set moving path L1 are the same as those in the first embodiment.

As shown in fig. 7, after the stirring pin F2 reaches the intermediate point S2 after the rotating tool F is rotated once, the operation transitions to the disengagement section. In the escape section, as shown in fig. 7, the stirring pin F2 is slowly pulled out (moved upward) from the intermediate point S2 toward the end position EP1, and the stirring pin F2 is disengaged from the extrusion porous tube 2 at the end position EP1 set on the set movement path L1.

The method for manufacturing a heat exchanger according to the second embodiment described above can provide substantially the same effects as those of the first embodiment. As in the second embodiment, the start position SP1 and the end position EP1 in the main joining process may be set on the set movement path L1.

(symbol description)

1 Heat exchanger

2 extruding out multi-hole pipe

3 cover body

F rotary tool

F2 stirring pin

Flat face of F3

J1 butt joint part

SP1 Start position

EP1 end position

W1 plasticized region.

Claims

1. A method of manufacturing a heat exchanger comprising a multi-hole extrusion tube having fins inside and a lid body for closing an opening of the multi-hole extrusion tube, wherein the multi-hole extrusion tube is joined to the lid body by friction stirring,

the lid body has a bottom portion and a peripheral wall portion rising from a peripheral edge of the bottom portion, a peripheral wall step portion is formed at an outer peripheral edge of the peripheral wall portion, the peripheral wall step portion has a step side surface and a step inclined surface which is inclined so as to approach the bottom portion side as facing outward from the step side surface,

the extruding multi-hole pipe has a fitting part at an end part, the fitting part is not provided with the fin and is used for being fitted with the peripheral wall part,

the extruded porous tube is formed of a second aluminum alloy, the lid body is formed of a first aluminum alloy, the first aluminum alloy being a material species having a hardness greater than that of the second aluminum alloy,

the rotating tool used in friction stirring includes a stirring pin that becomes tapered toward the leading end side,

the method of manufacturing the heat exchanger includes:

a butt joint step of forming a gap having a V-shaped cross section at a butt joint portion by inserting the peripheral wall portion of the lid body into the fitting portion of the porous extrusion pipe, so that an inner peripheral surface of the porous extrusion pipe overlaps a step side surface of the lid body, and so that an end surface of the porous extrusion pipe is butted against the step inclined surface of the lid body; and

a primary welding step of inserting only a stirring pin of the rotating tool into an outer peripheral surface of the perforated pipe, and rotating the rotating tool around the outer peripheral surface of the perforated pipe by a predetermined depth along a predetermined movement path set on the perforated pipe side of the butted portion while allowing the second aluminum alloy to flow into the gap in a state where the outer peripheral surface of the stirring pin and the step inclined surface of the lid body are in slight contact with each other, thereby friction-stirring the butted portion,

in the primary welding step, after the rotating stirring pin alone is inserted to a start position set on the side of the perforated pipe with respect to the set movement path, the stirring pin is gradually pushed into the predetermined depth while moving the rotation center axis of the rotating tool to a position overlapping the set movement path.

2. The method of manufacturing a heat exchanger according to claim 1,

in the primary welding step, the stirring pin is rotated at a predetermined rotation speed to perform friction stirring,

when the stirring pin is inserted in the primary welding step, the stirring pin is inserted while being rotated at a speed higher than the predetermined rotation speed, and the stirring pin is moved to the set movement path while gradually decreasing the rotation speed.

3. A method of manufacturing a heat exchanger comprising a multi-hole extrusion tube having fins inside and a lid body for closing an opening of the multi-hole extrusion tube, wherein the multi-hole extrusion tube is joined to the lid body by friction stirring,

the multi-hole extruding pipe has a fitting part at an end part, the fitting part is not formed with the fin and is used for fitting with the peripheral wall part,

the method of manufacturing the heat exchanger includes:

in the primary welding step, the stirring pin is inserted from a start position set on the set movement path, and the stirring pin is gradually pushed in to a predetermined height while moving the stirring pin in a traveling direction.

4. The method of manufacturing a heat exchanger according to claim 3,

5. A method of manufacturing a heat exchanger comprising a multi-hole extrusion tube having fins inside and a lid body for closing an opening of the multi-hole extrusion tube, wherein the multi-hole extrusion tube is joined to the lid body by friction stirring,

the method of manufacturing the heat exchanger includes:

in the primary welding step, an end position is set on the perforated pipe side of the set movement path, and after the friction stir welding of the butted portion, the rotating tool is moved to the end position and the stirring pin is slowly pulled out, thereby disengaging the rotating tool from the perforated pipe at the end position.

6. The method of manufacturing a heat exchanger according to claim 5,

when the stirring pin is disengaged in the primary joining step, the stirring pin is moved to an end position while gradually increasing the rotation speed from the predetermined rotation speed.

7. A method of manufacturing a heat exchanger comprising a multi-hole extrusion tube having fins inside and a lid body for closing an opening of the multi-hole extrusion tube, wherein the multi-hole extrusion tube is joined to the lid body by friction stirring,

the method of manufacturing the heat exchanger includes:

in the primary welding step, an end position is set on the set movement path, and after the friction stir welding of the butted portion, the stirring pin is slowly pulled out while the rotary tool is moved to the end position, and the rotary tool is disengaged from the extruded porous pipe at the end position.

8. The method of manufacturing a heat exchanger according to claim 7,

9. The method of manufacturing a heat exchanger according to any one of claims 1, 3, 5, and 7,

in the abutting step, the perforated tube and the lid body are formed so that the outer peripheral surface of the perforated tube is located outside the outer peripheral surface of the lid body.

10. The method of manufacturing a heat exchanger according to any one of claims 1, 3, 5, and 7,

the rotation direction and the advancing direction of the rotary tool are set so that the docking portion side becomes the advancing side.

11. The method of manufacturing a heat exchanger according to any one of claims 1, 3, 5, and 7,

in the primary joining step, the tip end of the stirring pin is rotated once around the outer peripheral surface of the perforated pipe while passing through the step side surface of the lid body, thereby performing friction stirring of the butted portion.

12. The method of manufacturing a heat exchanger according to any one of claims 1, 3, 5, and 7,

the first aluminum alloy is formed from a cast material and the second aluminum alloy is formed from an extended material.