JP7365646B2 - Linear friction welding method and joined structure - Google Patents

Description

The present invention relates to a linear friction welding method and a joined structure obtained by the linear friction welding method.

As the strength of metal materials such as steel and aluminum alloys increases, a decrease in strength at joints, which determines the mechanical properties of jointed structures, has become a serious problem. In contrast, in recent years, solid-phase joining methods have attracted attention and are rapidly being put into practical use, as the maximum temperature during welding does not reach the melting point of the materials to be joined, and the decrease in strength at the joint is smaller than that of conventional fusion welding. It's progressing.

In particular, "linear friction welding", which joins materials by reciprocating them while in contact, is similar to friction welding, which joins rotating cylindrical materials by pressing them against fixed materials. However, the shape of the material to be joined is not limited to a columnar or cylindrical shape. In addition, unlike friction stir welding, it does not require a tool to be press-fitted into the materials to be joined, so it can be easily applied to high-melting-point, high-strength metals such as steel and titanium.

The present inventor has also been actively studying solid phase joining methods for metal materials using linear friction welding. a first step of forming a welded interface by bringing them into contact with each other, and repeatedly sliding one member and the other member on the same trajectory while applying pressure substantially perpendicularly to the welded interface; It has a second step of discharging burrs from the interface to be joined, and a third step of stopping sliding to form a joining surface, and applying pressure to one member and/or the other member at a desired joining temperature. We are proposing a linear friction welding method characterized by setting the yield stress to be higher than the yield stress and lower than the tensile strength.

In the linear friction welding method described in Patent Document 1, increasing the applied pressure in linear friction welding increases the frictional heat, but since the softened material is continuously discharged as burrs, the softened material The "joining temperature" is determined by the pressure applied to the materials (force to expel burrs). In other words, when the applied pressure is set high, the welded material with higher strength (high yield strength) can be discharged as burrs. Here, "a state with a higher yield strength" means a "state with a lower temperature", and therefore, the "junction temperature" decreases as the applied pressure increases. Since the relationship between yield strength and temperature is approximately constant depending on the material, the bonding temperature can be controlled extremely accurately.

Furthermore, in Patent Document 2 (Japanese Unexamined Patent Publication No. 2018-122342), a first step of bringing one member into contact with another member to form a bonded interface, and applying pressure substantially perpendicularly to the bonded interface. a second step in which one member and the other member are repeatedly slid on the same trajectory while applying a In the second step, the interface to be joined is observed from a direction substantially perpendicular to the direction of sliding, and burrs are observed in the direction of sliding. This paper proposes a linear friction welding method characterized by executing the stop in the third step at the moment when the material is discharged substantially in parallel.

In the linear friction welding method described in Patent Document 2, the interface to be welded is observed from a direction substantially perpendicular to the direction of sliding, and burrs discharged substantially perpendicular to the direction of sliding are detected at the interface. By stopping sliding the moment it reaches both ends of the bonding interface, the amount of burr discharged is reduced compared to stopping sliding at the moment the burr is discharged approximately parallel to the direction of sliding. Although the amount increases slightly, it is possible to more reliably remove oxides, etc.

Japanese Patent Application Publication No. 2018-122344 Japanese Patent Application Publication No. 2018-122342

However, since the bonding interface formed by linear friction welding is limited to the sliding surface between the materials to be bonded, it is difficult to expand the bonding area. When it is required to improve the strength and reliability of a joint, expanding the joint area is effective, but this cannot be easily achieved with conventional linear friction welding.

In addition, if one of the materials to be joined is a resin material, it is difficult to generate appropriate frictional heat by sliding with the metal material, and it is difficult to form a good resin/metal joint using linear friction welding. I can't.

In view of the above-mentioned problems in the prior art, an object of the present invention is to provide a linear friction welding method that is capable of forming an overlapping joint portion in which the joining area can be easily expanded, and which is also capable of joining resin materials and metal materials. The objective is to provide a possible linear friction welding. Another object of the present invention is to provide a joined structure having a linear friction joint obtained by the linear friction joining and other joints.

In order to achieve the above object, the inventor of the present invention has conducted extensive research on linear friction welding methods, and has found that by conducting the frictional heat generated during linear friction welding, a joint separate from the linear friction weld is formed. We have discovered that it is extremely effective to do the following, and have arrived at the present invention.

That is, the present invention
Frictional heat is generated by linear friction joining between one member and the other,
Raising the temperature of the surface of the one member and/or the other member by heat conduction of the frictional heat,
joining the one member and/or the other member and at least one third member by bringing a third member into contact with the surface;
A heat conduction type linear friction welding method is provided.

In the thermally conductive linear friction welding method of the present invention, it is preferable that the third member and the one member and/or the other member be joined by overlap joining. By using overlap bonding, it is easy to expand the area of the bonding interface, and desired bonding strength can be obtained.

Here, if one member and the other member are made of the same material, it is possible to obtain a joint in which a member made of one type of material and a third member are overlapped and joined. Moreover, if one member and the other member are made of different materials, joining of these dissimilar materials and overlapping joining of the third member can be achieved simultaneously.

Linear friction welding is a solid phase welding method in which frictional heat is generated by linearly sliding the materials to be welded together, and a joint is formed by expelling burrs from the sliding surfaces. Here, since the temperature of one member and the other member increases due to the thermal conduction of the frictional heat, the linear friction welding conditions, the material, size (friction surface area, joint surface area, etc.) and shape of the welded materials are required. etc., it is possible to control the surface of one member and/or the other member to be a bonded region to an appropriate temperature.

Here, a joint can be formed by overlapping a third member on a desired region of one member and/or the other member whose surface temperature is set to an appropriate temperature. The third member may be brought into contact with a desired region from the time of linear friction welding, or may be brought into contact with a desired region at an appropriate timing. Further, the third member may be brought into contact with the region to be joined using the same fixing jig as the member to be joined, or a different fixing jig may be used.

Further, in the heat conduction type linear friction welding method of the present invention, it is preferable that the temperature of the surface is controlled by the friction pressure of the linear friction welding (linear friction welding pressure). If the linear friction welding temperature at which one member is joined to the other member can be determined, the "surface temperature" achieved by heat conduction can be accurately controlled. As a result of intensive study by the inventor, in linear friction welding, increasing the applied pressure of linear friction welding increases the frictional heat, but the softened material becomes burrs and is continuously discharged. Therefore, it has become clear that the "joining temperature" (temperature at the friction surface) is determined by the pressure applied to the softened material (force to expel burrs). In other words, when the applied pressure is set high, the welded material with higher strength (high yield strength) can be discharged as burrs. Here, "a state with a higher yield strength" means a "state with a lower temperature", and therefore, the "junction temperature" decreases as the applied pressure increases. Since the relationship between yield strength and temperature is approximately constant depending on the material, the bonding temperature can be controlled extremely accurately.

Further, in the heat conduction type linear friction welding method of the present invention, it is preferable that the temperature of the surface is controlled by the friction area of the linear friction welding. Since the amount of frictional heat generation can be controlled by the friction area, the "surface temperature" and "temperature increase area" achieved by heat conduction can be controlled. Here, when forming the joint interface of the third member on the member surface in the vicinity of the friction surface, a good joint can be obtained by making the friction area equal to or larger than the desired joint interface area. In addition, for example, increasing the frequency or amplitude of linear sliding in linear friction welding increases the temperature increase rate, and decreasing the frequency or amplitude decreases the temperature increase rate.

Further, in the heat conduction type linear friction welding method of the present invention, it is preferable that the one member and the other member are metal members, and the third member is a resin member. When joining metal materials, it is necessary to remove surface impurities such as an oxide film as a preliminary treatment for joining, or to use an appropriate insert material, depending on the situation. On the other hand, by using a resin member as the third member, a good joint can be obtained by controlling the temperature of the interface to be joined to an appropriate temperature. Further, even when applying a bonding pressure to bond the third member, the bonding pressure can be set to a small value.

Furthermore, in the thermally conductive linear friction welding method of the present invention, when the third member is a resin member, the surface (the surface of one member and/or the other member) is subjected to a silane coupling treatment; is preferred. By performing silane coupling treatment on the bonded interface between the metal member and the resin member, it is possible to increase the number of chemical bonds that contribute to bonding, and it is possible to form a strong bonded interface.

Moreover, in the thermally conductive linear friction welding method of the present invention, it is preferable that the one member and/or the other member be made of steel, a titanium alloy, an aluminum alloy, or a magnesium alloy. Since steel has a wide variety of compositions and a wide range of thermal conductivity, it is easy to select a steel having an appropriate thermal conductivity. In addition, titanium alloys, aluminum alloys, and magnesium alloys are light metals and have high specific strength, so they can be used as structural members for transportation equipment, etc., which are in desperate need of weight reduction, especially when combined with resin materials. It can be suitably used.

Further, in the heat conduction type linear friction welding method of the present invention, it is preferable that the third member is made of carbon fiber reinforced resin. Carbon fiber reinforced resin is a composite material made of carbon fibers and a resin matrix, and its strength is mainly expressed by the carbon fibers. Here, since carbon fibers and metal materials, which basically consist of covalent bonds, cannot be directly bonded, the bonding interface between the resin matrix and metal material is responsible for the strength in bonding carbon fiber reinforced resin and metal materials. becomes. As a result, it is extremely difficult to obtain sufficient joint strength with butt joints where the joint area is small, but with the thermally conductive linear friction welding method of the present invention, it is possible to form overlapping joints. Since an arbitrary bonding area can be determined in overlap bonding, a good joint with high bonding strength can be obtained even when the third member is made of carbon fiber reinforced resin.

Further, in the heat conduction type linear friction welding method of the present invention, it is preferable that a welding pressure is applied during the overlapping joining of the one member and/or the other member and the third member. If one member and/or the other member and the third member are in good contact with each other at the interface to be joined that has been heated to an appropriate temperature, it is possible to join these members. Bonding strength can be improved by applying pressure.

Moreover, the present invention
a linear friction joint between one member and the other member;
having a joint between the one member and/or the other member and a third member;
Also provided is a bonded structure characterized by the following.
Preferably, the joint is a lap joint.

One member and the other member may be made of the same material or may be made of different materials. Further, the number of linear friction joints and other joints is not particularly limited, and it may have a plurality of linear friction joints and a plurality of joints other than the linear friction joints. In addition, a "linear friction joint" broadly includes a joint formed by linear friction joint between one member and another member, and can be, for example, a butt joint or a T-joint.

In the bonded structure of the present invention, it is preferable that the one member and the other member are metal members, and the third member is a resin member. Generally, resin parts have lower strength than metal parts, so by joining them using overlap joints that can easily expand the joint area, it is possible to ensure the desired strength and reliability according to each application. I can do it.

Moreover, in the bonded structure of the present invention, it is preferable that the one member and/or the other member be made of steel, a titanium alloy, an aluminum alloy, or a magnesium alloy. By making one member and/or the other member steel, it can be utilized as various structural members used in various industries. In addition, titanium alloys, aluminum alloys, and magnesium alloys are light metals and have high specific strength, so they can be used as structural members for transportation equipment, etc., which are in desperate need of weight reduction, especially when combined with resin materials. It can be suitably used.

Furthermore, in the bonded structure of the present invention, it is preferable that the third member is a carbon fiber reinforced resin. By joining carbon fiber-reinforced resins at overlapping joints, the joint area can be adjusted, and even carbon fiber-reinforced resins made of high-strength carbon fibers and a resin matrix can maintain sufficient strength and reliability. It can be a bonded structure having.

The bonded structure of the present invention can be suitably obtained using the heat conduction type linear friction welding method of the present invention.

According to the present invention, it is possible to provide a linear friction welding that can form an overlapping joint portion in which the joining area can be easily expanded, and can also join a resin material and a metal material. Further, according to the present invention, it is also possible to provide a joined structure having a linear friction joint obtained by the linear friction joining and other joints.

FIG. 2 is a schematic diagram showing a situation during general linear friction welding. FIG. 2 is a schematic diagram of heat conduction type linear friction welding (overlap welding) of the present invention. FIG. 2 is a schematic diagram of a thermally conductive linear friction weld (butt joint) of the present invention. FIG. 2 is a schematic diagram of a bonded structure having overlapping bonded portions. FIG. 2 is a schematic diagram of a joined structure consisting only of butt joints. FIG. 3 is a schematic diagram showing the state of heat conduction type linear friction welding in Example 1. It is a photograph of the appearance of a joint obtained under the condition of a frequency of 15 Hz. 2 is a graph showing the joint interface strength of each joint obtained in Example 1 and Example 2. FIG. 7 is a schematic diagram showing the state of bonding in Example 3. 3 is a photograph of the appearance of a joint obtained in Example 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, typical embodiments of a thermally conductive linear friction welding method and a welded structure of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. In the following description, the same or equivalent parts are given the same reference numerals, and redundant descriptions may be omitted. Further, since the drawings are for conceptually explaining the present invention, the dimensions of the illustrated components and their ratios may differ from the actual ones.

(1) Heat conduction type linear friction welding method Figure 1 shows a schematic diagram showing the situation during general linear friction welding. Linear friction welding is a solid phase welding that uses the frictional heat generated when the materials to be joined are rubbed together in linear motion as the main heat source. In linear friction welding, the material softened by temperature rise is discharged as burrs from the interface to be joined, thereby removing the oxide film that had formed on the interface, and forming a joint by bringing the newly formed surfaces into contact with each other. do.

FIG. 2 shows a schematic diagram of the heat conduction type linear friction welding (overlap welding) of the present invention. Here, a case will be described in which one member 2 and the other member 4 are butt-joined by linear friction welding, and one member 2 and the third member 6 are overlap-joined.

The method of linearly friction welding one member 2 and the other member 4 is not particularly limited as long as it does not impair the effects of the present invention, and linear friction welding methods using various conventionally known linear friction welding devices may be used. be able to. Further, the materials, sizes, and dimensions of one member 2 and the other member 4 are not particularly limited as long as they do not impair the effects of the present invention, and may be any material that can be joined by a conventionally known linear friction welding method.

In the heat conduction type linear friction welding of the present invention, one member 2 and the other member 4 are brought into contact with each other at the welded interface 8, and linear sliding is performed while applying a welding pressure P1 to the welded interface 8. By doing so, frictional heat is generated at the welded interface 8. Here, the third member 6 is superimposed on an arbitrary surface of the one member 2 to form an overlapping welded interface 10, and the frictional heat due to linear friction welding is thermally conducted and rises up the overlapping welded interface 10. By heating, overlapping bonding between the one member 2 and the third member 6 is achieved. Note that FIG. 2 shows a case where one member 2 and the third member 6 are fixed, and the other member 4 vibrates.

In the overlapping joining of the one member 2 and the third member 6, it is preferable to apply the overlapping joining pressure P2 in a substantially perpendicular direction to the overlapping and joining interface 10. A pressing mechanism may be provided for the purpose of applying the bonding pressure P2. For example, the bonding pressure P2 may be expressed by gripping one member 2 and the third member 6 with one fixing jig. good.

The temperature of the overlapping and welded interface 10 is increased by thermal conduction of frictional heat generated by linear frictional welding. That is, the temperature of the superimposed and welded interface 10 depends on the joining conditions (joining pressure, amplitude, frequency, approach distance, etc.) of linear friction welding that joins one member 2 and the other member 4, and the one member 2 and the other member 4. The friction area of the members 4, the distance between the overlapped interface 10 and the interface 8, the thermal conductivity of one member 2 and the other member 4, the size and thermal conductivity of the fixing jig, etc. be able to.

FIG. 3 shows a schematic diagram of the heat conduction type linear friction welding (butt welding) of the present invention. Here, a case will be described in which one member 2 and the other member 4 are butt-joined by linear friction welding, and one member 2 and the third member 6 are butt-joined. For example, one member 2 may be provided with a concave portion and the third member 6 may be provided with a convex portion at the ends where one member 2 and the third member 6 are brought into contact with each other, and the two members may be fitted with each other.

In the embodiment shown in FIG. 3, the temperature of the welded interface 12 where one member 2 and the third member 6 are in contact is raised due to the thermal conduction of frictional heat generated at the welded interface 8 in linear friction welding. One member 2 and third member 6 will be joined. Note that FIG. 3 shows a case where one member 2 and the third member 6 are fixed, and the other member 4 vibrates.

At the interface 12 to be joined, the one member 2 and the third member 6 are not sliding, and the joining is achieved by raising the temperature and pressing. /Or in the case where the end face of the third member 6 is subjected to silane coupling treatment or the like, a good bonding interface can be obtained without removing the treated surface.

(2) Joined Structure Regarding the joined structure of the present invention, schematic diagrams are shown in FIGS. 4 and 5, respectively, when it has an overlapping joint and when it consists of only a butt joint. Note that although these bonded structures show cases in which three members are bonded, the bonded structure of the present invention is not limited to this, and may be bonded using a linear friction joint and temperature increase due to heat conduction. It suffices as long as it has a joint part that is

In FIG. 4, one member 2 and the other member 4 are joined via a linear friction bonding interface 20, and a third member 6 and one member 2 are bonded via an overlap bonding interface 22. . Here, since the area of the overlapping bonding interface 22 can be easily expanded, for example, even if the third member 6 is made of carbon fiber reinforced resin made of high strength carbon fiber and a resin matrix, it has sufficient strength. A reliable bonded structure can be obtained.

In FIG. 5, one member 2 and the other member 4 are joined via a linear friction welding interface 20, and a third member 6 and one member 2 are joined via a butt joining interface 24. Here, the butt joint interface 24 is formed by raising the temperature and applying a joining pressure, and for example, even when a silane coupling treatment is performed, the treated surface is not removed. A good bonding interface is formed.

One member 2 and/or the other member 4 are not particularly limited as long as they do not impair the effects of the present invention, and various conventionally known structural materials that can be joined by linear friction welding can be used. , titanium alloy, aluminum alloy, and magnesium alloy. By making one member 2 and/or the other member 4 of steel, they can be utilized as various structural members used in various industries. In addition, titanium alloys, aluminum alloys, and magnesium alloys are light metals and have high specific strength, so they can be used as structural members for transportation equipment, etc., which are in desperate need of weight reduction, especially when combined with resin materials. It can be suitably used.

The third member 6 is also not particularly limited as long as it does not impair the effects of the present invention, and may be made of various conventionally known structural materials, but is preferably made of carbon fiber reinforced resin. By joining carbon fiber-reinforced resins at overlapping joints, the joint area can be adjusted, and even carbon fiber-reinforced resins made of high-strength carbon fibers and a resin matrix can maintain sufficient strength and reliability. It can be a bonded structure having.

Although typical embodiments of the present invention have been described above, the present invention is not limited to these, and various design changes are possible, and all such design changes are included within the technical scope of the present invention. It will be done.

≪Example 1≫
In the manner shown in Fig. 6, aluminum alloy (A6061-T6) plates were linearly friction welded together, and at the same time, one aluminum alloy plate and a carbon fiber reinforced resin (CFRP, polyamide 6 with 20 wt% carbon fiber addition) plate were overlapped and bonded. . Here, the surface of the aluminum alloy plate forming the overlap bonding interface was subjected to silane coupling treatment. The silane coupling agent is OFS-6040 (3-Glycidoxypropyl trimethoxysilane, epoxy functional), which can introduce epoxy groups into the surface of the aluminum alloy plate.

The shapes and sizes of the aluminum alloy plate and carbon fiber reinforced resin are as shown in Figure 6 (unit: mm), and the linear friction bonding conditions were: applied pressure of 50 MPa, amplitude of 2 mm, frequency of 15 to 50 Hz, and offset margin. It was set to 3 mm. The carbon fiber reinforced resin was fixed integrally with the aluminum alloy plate using a fixing jig while being in contact with the surface of the aluminum alloy plate. In linear friction welding, the aluminum alloy plate in contact with the carbon fiber reinforced resin was used as the stationary side, and the other aluminum alloy plate was used as the vibration side.

FIG. 7 shows a photograph of the appearance of the joint obtained under the condition of a frequency of 15 Hz. It can be seen that a linear friction joint between the aluminum alloys and an overlap joint between the aluminum alloy and the carbon fiber reinforced resin are formed. Note that for the aluminum alloy plate that was brought into contact with the carbon fiber reinforced resin, areas that did not contribute to overlapping bonding were cut off.

≪Example 2≫
Titanium alloy plates were linearly friction welded together in the same manner as in Example 1, except that titanium alloy (Ti-6Al-4V) was used for linear friction welding, and at the same time one titanium alloy plate and carbon fiber reinforced resin ( CFRP and 20wt% carbon fiber-added polyamide 6) plates were overlapped and bonded.

A tensile test was conducted on each joint obtained in Example 1 and Example 2, and the joint interface strength was calculated by dividing the measured test load by the joint area. The results obtained are shown in FIG. For comparison, a titanium alloy (Ti-6Al-4V) plate and a carbon fiber reinforced resin (CFRP, polyamide 6 with 20 wt% carbon fiber added) plate were fabricated by friction stir welding (FSW) using the same silane coupling treatment as in Example 1. The bonding interface strength obtained when these are overlapped and bonded is also shown. As shown in FIG. 8, the lap joint obtained by thermally conductive linear friction welding of the present invention has sufficiently high joint interface strength compared to the lap joint obtained by friction stir welding. I can see that

Here, although no large difference was observed in the bonding interface strength shown in FIG. 8, the bonding area increased as the frequency of linear friction welding decreased in both cases of the aluminum alloy plate and the titanium alloy plate. This is because the lower the frequency, the lower the rate of temperature rise due to friction, and the longer the bonding time. It is thought that as the bonding time increases, the frictional heat is conducted over a wider area, expanding the bonding area (note that even if the amplitude is reduced, the bonding time becomes longer). In addition, the thermal conductivity of aluminum alloy and titanium alloy is 180 W/m・K and 7.2 W/m・K, respectively, and aluminum alloy with high thermal conductivity has a higher thermal conductivity than titanium alloy under the same linear friction welding conditions. The bonding area was approximately twice that of the case.

The conditions for friction stir welding performed for comparison were: the rotation speed of the tool was 300 rpm, the moving speed of the tool (welding speed) was 100 mm/min, the advancing angle of the tool was 3°, and the bottom surface was smooth with no protrusions. Friction stir welding was performed using a cylindrical cemented carbide friction stir welding tool with a diameter of 15 mm. Argon gas was flowed through the joint, and the bottom of the tool was inserted 0.9 mm from the surface of the pure titanium plate.

≪Example 3≫
In the manner shown in Fig. 9, titanium alloy (Ti-6Al-4V) plates are linearly friction welded, and at the same time, one titanium alloy plate and a carbon fiber reinforced resin (CFRP, polyamide 6 with 20 wt% carbon fiber) plate are butt welded. did. Here, the same silane coupling treatment as in Example 1 was performed on the surface of the titanium alloy plate forming the butt joint interface. The linear friction welding conditions were as follows: applied pressure was 50 MPa, amplitude was 2 mm, frequency was 15 Hz, and offset was 1.5 mm.

A photograph of the front appearance of the obtained joint is shown in FIG. It can be seen that in addition to linear friction welding of the titanium alloy plates, the titanium alloy plates and carbon fiber reinforced resin are butt welded. The bond between the titanium alloy plate and the carbon fiber reinforced resin is formed by heat conduction from the linear friction bond and bonding pressure applied by the linear friction bond.

2...One member,
4...other member,
6...Third member,
8... Bonded interface,
10... overlapped interface to be joined,
12... bonded interface,
20...Linear friction bonding interface,
22... overlap bonding interface,
24...Butt joint interface.

Claims (9)

Frictional heat is generated by linear friction joining between one member and the other,
Raising the temperature of the surface of the one member and/or the other member by heat conduction of the frictional heat,
joining the one member and/or the other member and at least one third member by bringing a third member into contact with the surface;
A thermally conductive linear friction welding method featuring: The joining of the third member and the one member and/or the other member is an overlapping joining;
The thermally conductive linear friction welding method according to claim 1, characterized in that: controlling the temperature of the surface by the friction pressure of the linear friction welding;
The thermally conductive linear friction welding method according to claim 1 or 2, characterized in that: controlling the temperature of the surface by the friction area of the linear friction weld;
The thermally conductive linear friction welding method according to any one of claims 1 to 3, characterized in that: The one member and the other member are metal members,
The third member is a resin member;
The thermally conductive linear friction welding method according to any one of claims 1 to 4, characterized in that: applying silane coupling treatment to the surface;
The thermally conductive linear friction welding method according to claim 5. The one member and/or the other member are made of steel, titanium alloy, aluminum alloy, and magnesium alloy;
The thermally conductive linear friction welding method according to any one of claims 1 to 6, characterized in that: The third member is made of carbon fiber reinforced resin;
The thermally conductive linear friction welding method according to any one of claims 1 to 7, characterized in that: Applying a joining pressure in the overlapping joining of the one member and/or the other member and the third member;
The thermally conductive linear friction welding method according to claim 2 , characterized in that: