Hollow metal member manufacturing method, hollow metal member, and rotary tool

Abstract

To manufacture a hollow metal member while securing the degree of freedom of the shape of an internal space.SOLUTION: A method for manufacturing a hollow metal member includes a step of preparing a recessed metal member (46) in which a recess (44) corresponding to a desired internal space shape is formed, and a step of moving a rotary tool (6) along an opening of the recess (44) while pressing the rotary tool (6) against an opening surface (42) of the recessed metal member (46), and closing the recess (44) with a softened material of the opening surface (42).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a hollow metal member. [Background technology]

[0002] For example, hollow metal components, which are metal components with an internal space, are manufactured to form components with an internal space through which liquids or gases can pass. A method using friction stir processing (FSP) is known as a manufacturing method for such hollow metal components.

[0003] An example of a method for manufacturing a hollow metal member using friction stir processing (FSP) is disclosed in Japanese Patent Laid-Open No. 2014-223680 (Patent Document 1). In the method of Patent Document 1, a rotary tool is used to move the rotary tool along the surface of the metal member while rotating, forming shallow grooves and simultaneously covering the grooves, thereby forming a tunnel-like internal space inside the metal member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-223680 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method of Patent Document 1 has a problem in that the shape of the internal space formed inside the hollow metal member is restricted by the shape of the rotary tool.

[0006] Therefore, it is desirable to be able to manufacture hollow metal members while ensuring freedom in the shape of the internal space. [Means for solving the problem]

[0007] The method for manufacturing a hollow metal member according to the present disclosure includes: A method for manufacturing a hollow metal member, which is a metal member having an internal space, using a rotary tool, comprising: a step of preparing a recessed metal member having a recess corresponding to a desired internal space shape formed from the surface to the interior of the metal member; a step of moving the rotary tool along the opening of the recess while pressing it against an opening surface, which is the surface on which the recess is formed in the recessed metal member, and closing the recess with the softened material on the opening surface; Includes.

[0008] According to this configuration, a hollow metal component is formed with a recess shaped according to the desired internal space shape, extending from the surface to the interior of the metal component, regardless of the shape of the rotary tool. While pressing the rotary tool against the surface of the recess, the rotary tool is moved along the opening of the recess. This allows the recess to be filled with softened material using friction stir processing (FSP). This allows for the formation of a hollow metal component with a high degree of freedom in the shape of the internal space.

[0009] Further features and advantages of the techniques according to the present disclosure will become more apparent from the following description of exemplary and non-limiting embodiments, which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view of a hollow metal member according to a first embodiment; [Figure 2] A perspective view of a grooved metal member [Figure 3] 1 is a cross-sectional view showing one aspect of the closing process. [Figure 4] FIG. 1 is a plan view showing one phase of the closing process. [Figure 5] Offset width of the rotary tool relative to the groove [Figure 6] Plan view of hollow metal member [Figure 7] Cross section taken along the line VII-VII in Figure 6 [Figure 8] Cross section VIII-VIII in Figure 6 [Figure 9] 10 is a plan view of a perforated metal member according to a second embodiment; [Figure 10] Cross-sectional view of a metal member with holes [Figure 11] FIG. 1 is a plan view showing one phase of the closing process. [Figure 12] Offset width of the rotary tool relative to the hole [Figure 13] Plan view of hollow metal member [Figure 14] 10 is a schematic front view of a fixing tool used in the third embodiment; [Figure 15] Enlarged view of part of Figure 14 [Figure 16] Schematic bottom view of the fixing tool [Figure 17] 1 is a cross-sectional view showing one aspect of the closing process. [Figure 18] FIG. 1 is a plan view showing one phase of the closing process. [Figure 19] A perspective view of a hollow metal member [Figure 20] Cross-sectional view of a hollow metal member [Figure 21] A photo showing the blocked area as seen from the inside of the space DETAILED DESCRIPTION OF THE INVENTION

[0011] [First embodiment] A first embodiment of a hollow metal member 1 and a method for manufacturing the hollow metal member (a method for manufacturing a hollow metal member) will be described with reference to the drawings.

[0012] The hollow metal member 1 of this embodiment is part of a cooling member 90 that constitutes a cooling device together with, for example, a refrigerant circuit, a pump, etc. The cooling member 90 is formed in a block shape using a metal material, and as shown in Fig. 1, includes a flow path space 91 through which a refrigerant flows, and an inlet 92 and an outlet 93 that respectively communicate this flow path space 91 with the outside. A refrigerant circuit is connected to the inlet 92 and the outlet 93 directly or indirectly via a connecting member, etc.

[0013] The hollow metal member 1 is used as the original component of the cooling member 90. The hollow metal member 1 is a metal member having an internal space 21. The hollow metal member 1 comprises a main body 2 and a blocking portion 3 formed on the surface side of the main body 2. In this embodiment, the main body 2 is formed in the shape of a flattened rectangular parallelepiped. The internal space 21 is formed inside the main body 2. In this example, the internal space 21 is not simply linear but extends two-dimensionally. The blocking portion 3 blocks the internal space 21 on the surface side of the main body 2. As a result, the hollow metal member 1 of this embodiment has a sealed internal space 21.

[0014] Through holes communicating with the internal space 21 are formed on two opposing side surfaces of this hollow metal member 1, thereby forming a cooling member 90. In this case, the two through holes serve as an inlet 92 and an outlet 93, and the internal space 21 serves as a flow path space 91.

[0015] 1 is referred to as the Z direction, the longitudinal direction of the hollow metal member 1 as viewed from the Z direction is referred to as the X direction, and the lateral direction is referred to as the Y direction. The internal space 21 of the hollow metal member 1 in this embodiment is a space that expands in both the X direction and the Z direction.

[0016] In the hollow metal member manufacturing method of this embodiment, friction stir processing (FSP) is used to manufacture the hollow metal member 1. That is, in the hollow metal member manufacturing method of this embodiment, a rotary tool 6 that rotates at high speed is used to manufacture the hollow metal member 1 through a step of stirring, by plastic flow, a material softened by frictional heat.

[0017] The method for manufacturing a hollow metal member includes a step of preparing a recessed metal member 46 (hereinafter referred to as the "preparation step") and a step of closing the recess 44 formed in the recessed metal member 46 (hereinafter referred to as the "closing step").

[0018] In the preparation step, a recessed metal member 46 is prepared, in which a recess 44 is formed from the surface of the metal member 41 to the inside. The recess 44 is a portion recessed from the surface of the metal member 41 toward the inside, and can be of any depth, and may be closed or open on the opposite side. In this embodiment, in the preparation step, a grooved metal member 46A is prepared, in which a groove 44A extending in the longitudinal direction to a predetermined depth is formed from the surface of the metal member 41 to the inside, as shown in FIG.

[0019] The metal material constituting the metal member 41 is not particularly limited as long as it is a metal that can be friction-stirred, and examples that can be used include aluminum, copper, titanium, magnesium, and alloys thereof. When used as part of the cooling member 90 as in this embodiment, a metal with high thermal conductivity (such as copper or aluminum) is preferred.

[0020] The grooved metal member 46A as the recessed metal member 46 may be formed by casting, for example. In this case, the grooved metal member 46A is formed as a metal member 41 in which grooves 44A as recesses 44 are formed from the beginning. The grooved metal member 46A may also be formed by subjecting the metal member 41 as a base body to cutting, for example. In this case, the grooved metal member 46A is formed by subsequently forming the grooves 44A in the metal member 41. In either case, by adjusting the mold shape and the processed shape, grooved metal members 46A having grooves 44A of various shapes can be formed.

[0021] The shape of the grooves 44A in the grooved metal member 46A is determined according to the shape of the internal space 21 of the hollow metal member 1 to be finally obtained. That is, the shape of the grooves 44A is determined so as to encompass the shape of the desired internal space 21 and to extend in at least one direction so as to open onto the surface of the metal member 41. In this embodiment, the surface where the grooves 44A open is referred to as the opening surface 42. In the example shown in FIG. 2, the grooved metal member 46A has grooves 44A that have the same shape as the desired internal space 21 and extend in the Z direction all the way to the opening surface 42.

[0022] That is, the grooves 44A of the grooved metal member 46A have dimensions in the X and Y directions that are the same as the internal space 21 of the hollow metal member 1 to be finally obtained, and are formed so as to open to the surface with a dimension in the Z direction that is longer than the internal space 21. When the grooves 44A of this grooved metal member 46A are considered as a reference, the depth direction of the grooves 44A is the Z direction, the extension direction is the X direction, and the width direction is the Y direction.

[0023] The entity that forms the grooved metal member 46A may be the same as or different from the entity that manufactures the hollow metal member 1. That is, in the preparation step, the entity that manufactures the hollow metal member 1 may prepare the grooved metal member 46A by itself, or may prepare the grooved metal member 46A by procuring it from another entity that has formed it.

[0024] In the closing step, the grooves 44A are closed by a friction stir process (FSP) on the grooved metal member 46A. The friction stir process (FSP) is performed using a friction stir device including a rotary tool 6, a drive unit that rotates the rotary tool 6, and a pressing unit that applies a pressing force to the rotary tool 6 along the direction of the rotation axis.

[0025] In this embodiment, the rotary tool 6 is a standard tool commonly used for friction stir processing (FSP). As shown in FIG. 3, the rotary tool 6 has a shoulder 61 and a probe 62 integrally provided with the shoulder 61. The shoulder 61 is formed in a cylindrical shape that is rotatable around a rotation axis A. The shoulder 61 is drivingly connected to a drive unit and rotates around the rotation axis A by power from the drive unit. The shoulder 61 is also drivingly connected to a pressing unit and can advance and retreat along the rotation axis A.

[0026] The probe 62 is provided coaxially with the shoulder 61 and protrudes further downward from the lower surface of the shoulder 61. The probe 62 is formed in a cylindrical shape with a substantially constant diameter. The probe 62 is formed with a smaller diameter than the shoulder 61. The probe 62 rotates around the rotation axis A together with the shoulder 61 by power from the drive unit. The probe 62 is also drivingly connected to the pressing unit, and can move forward and backward along the rotation axis A together with the shoulder 61.

[0027] The rotary tool 6 is made of a high-hardness material such as high-speed tool steel, alloy tool steel, cemented carbide, or ceramics.

[0028] In the closing process, first, as shown in FIG. 3, the rotary tool 6 is rotated at high speed and pressed against a position adjacent to the groove 44A on the opening surface 42 of the grooved metal member 46A. In this embodiment, the rotary tool 6 is pressed against a position adjacent (offset) to the groove 44A on the opening surface 42 of the grooved metal member 46A in the Y direction, which is the width direction of the groove 44A. This causes frictional heat to locally increase the temperature of the metal material constituting the grooved metal member 46A, softening it, and the probe 62 penetrates into the grooved metal member 46A. At this time, the probe 62 penetrates into the grooved metal member 46A until the lower surface of the shoulder 61 comes into contact with the opening surface 42 of the grooved metal member 46A.

[0029] Next, while maintaining this state, as shown in FIG. 4 , the rotary tool 6 is moved relatively along a position adjacent to the groove portion 44A on the opening surface 42 of the grooved metal member 46A. That is, with the probe 62 inserted into the grooved metal member 46A until the lower surface of the shoulder 61 contacts the opening surface 42, the rotary tool 6 is moved relatively along a position adjacent to the groove portion 44A on the opening surface 42 of the grooved metal member 46A while rotating at high speed. In this embodiment, the rotary tool 6 is moved relatively along the X direction, which is the extension direction of the groove portion 44A, at a position on the opening surface 42 of the grooved metal member 46A adjacent to the groove portion 44A in the Y direction. As a result, the metal material constituting the grooved metal member 46A gradually softens due to frictional heat and flows toward the opening surface 42 of the groove portion 44A, and the softened material closes the groove 44A.

[0030] As described above, in the closing process, the rotary tool 6 is moved (relatively moved) along a trajectory parallel to the opening edge of the groove 44A while being pressed against the opening surface 42 of the grooved metal member 46A. Specifically, the rotation axis A of the rotary tool 6 is moved along the above trajectory. The above trajectory is offset in the width direction of the groove 44A with respect to the groove 44A (specifically, the center of the groove 44A in the width direction). In other words, it is a linear trajectory parallel to the opening edge of the groove 44A along the X direction. In the closing process, the rotary tool 6 is moved linearly along the opening edge of the groove 44A along the X direction. As is clear from the above description, moving along the opening edge includes moving along a position offset from the opening edge. Then, in the closing process, the groove 44A is closed with the softened material of the opening surface 42.

[0031] The flow of the softened metal material is a plastic flow in which the solid phase is maintained, and the softened metal that reaches the region of groove 44A on the opening surface 42 side, which is the portion located near probe 62, remains in that position (i.e., it does not flow down to the bottom side of groove 44A). Therefore, groove 44A can be appropriately blocked with the softened material.

[0032] The relative movement of the rotary tool 6 may be performed by moving the rotary tool 6 while the grooved metal member 46A, which is the workpiece, is held on a fixed table, or by moving the grooved metal member 46A held on a movable table while the rotary tool 6 is held in a predetermined position. Alternatively, the rotary tool 6 may be moved relatively by moving both the rotary tool 6 and the grooved metal member 46A. Which mode to adopt may be selected depending on the specifications of the friction stir welding apparatus to be used.

[0033] The processing conditions for the closing step are not particularly limited, but are preferably determined appropriately depending on the material and size of the rotary tool 6 and the grooved metal member 46A, which is the workpiece. The rotation speed of the rotary tool 6 can be, for example, 1000 to 5000 rpm. The pressing pressure of the rotary tool 6 against the grooved metal member 46A can be, for example, 10 to 20 MPa. The relative movement speed of the rotary tool 6 can be, for example, 200 to 1000 mm / min.

[0034] 5, the offset of the rotary tool 6 in the Y direction relative to the groove 44A (i.e., the above-mentioned trajectory) is set so that a portion of the rotary tool 6 is located inside the opening edge of the recess 44 (groove 44A in this embodiment). Specifically, the offset of the rotary tool 6 in the Y direction relative to the groove 44A is preferably set so as to satisfy the following condition. Here, of the inner surfaces facing the Y direction, which is the width direction of the groove 44A, the inner surface to which the rotary tool 6 is offset is referred to as a reference inner surface 51 of the recess 44, and the other inner surface (the inner surface opposite to the reference inner surface 51) is referred to as an opposing inner surface 52.

[0035] 5, the diameter of the shoulder 61 of the rotary tool 6 (hereinafter referred to as the "shoulder diameter") is "S," the diameter of the probe 62 (hereinafter referred to as the "probe diameter") is "P," and the width of the groove 44A in the Y direction (hereinafter referred to as the "groove width") is "G." Furthermore, the distance in the Y direction from the reference inner surface 51 of the recess 44 (groove 44A) to the rotation axis A of the rotary tool 6 along the opening surface 42 (hereinafter referred to as the "offset width") is "F." Furthermore, the distance in the Y direction from the reference inner surface 51 of the groove 44A to the highest point of the rotary tool 6 along the opening surface 42 (hereinafter referred to as the "machining allowance") is "R."

[0036] It is preferable that the offset of the rotary tool 6 is set so that the ratio of the offset width F from the reference inner surface 51 of the groove 44A to the rotation axis A of the rotary tool 6 to the probe diameter P (hereinafter referred to as the "offset ratio (F / P)") is between 0 and 1. By setting the offset ratio (F / P) to 0 or greater, a sufficient amount of metal material can be secured that is softened by the friction stir process (FSP) and flows into the groove 44A. Furthermore, if the offset ratio (F / P) is too large, the metal material softened by the friction stir process (FSP) will not be able to reach the groove 44A, but by setting the offset ratio (F / P) to 1 or less, it is possible to ensure that the softened metal material flows into the groove 44A.

[0037] The highest point of the rotary tool 6 from the reference inner surface 51 of the groove portion 44A is a position that is advanced in the Y direction by the radius (0.5P) of the probe 62 from the rotation axis A of the rotary tool 6. Therefore, when the offset ratio (F / P) is "0", the ratio of the machining allowance R to the probe diameter P (hereinafter referred to as the machining allowance ratio (R / P)) is "0.5", and when the offset ratio (F / P) is "1", the machining allowance ratio (R / P) is "1.5". In other words, the above-mentioned condition "the offset ratio (F / P) is 0 or more and 1 or less" is equivalent to the condition "the machining allowance ratio (R / P) is 0.5 or more and 1 or less".

[0038] In the closing process, when determining the pressing position of the rotary tool 6 against the opening surface 42 of the grooved metal member 46A, it is sufficient to satisfy the corresponding conditional expression based on the offset width F or the processing allowance R, whichever is easier to manage.

[0039] Additionally, the offset width F is preferably set within a range in which the shoulder 61 of the rotary tool 6 covers the opposing inner surface 52 of the groove 44A. Here, the distance in the Y direction along the opening surface 42 from the opposing inner surface 52 of the groove 44A to the rotation axis A of the rotary tool 6 is equal to the sum of the offset width F and the recess width G. If the distance from the opposing inner surface 52 to the rotation axis A is equal to or less than the radius (0.5S) of the shoulder 61, the shoulder 61 will cover the opposing inner surface 52 of the groove 44A. Therefore, more quantitatively, the offset width F is preferably set to be equal to or less than the difference between the radius (0.5S) of the shoulder 61 and the recess width G (F≦0.5SG). In this embodiment, the recess width G is the groove width Ga, which is the width in the Y direction perpendicular to the movement trajectory of the groove 44A, and the offset width F is preferably set to be equal to or less than the difference between the radius (0.5S) of the shoulder 61 and the groove width Ga (F≦0.5S−Ga). In this way, the groove 44A can be closed in one pass (that is, in one process on one side of the groove 44A in the Y direction), resulting in good processing efficiency.

[0040] Of course, the offset width F does not necessarily have to be set so that the shoulder 61 covers the opposing inner surface 52. In such a case, the groove 44A may be closed in two passes. That is, after a first process on one side of the groove 44A in the Y direction, a second process may be performed on the opposite side (the other side in the Y direction) of the groove 44A, and the groove 44A may be closed by the cooperation of both processes. In this case, the offset width F is preferably set within a range in which the shoulder 61 of the rotary tool 6 covers the center position of the groove 44A in the width direction. More quantitatively, it is preferably set to half the difference between the shoulder diameter S and the recess width G (F≦0.5(SG)). In this embodiment, the offset width F is preferably set to half the difference between the shoulder diameter S and the groove width Ga (F≦0.5(S−Ga)).

[0041] The length of the probe 62 of the rotary tool 6 (hereinafter referred to as the "probe length" and shown as "Q" in FIG. 5) is preferably set to a length that ensures sufficient strength during processing. The probe length Q is typically set to be approximately the same as or shorter than the probe diameter P.

[0042] Furthermore, in this embodiment, in relation to the recess width G, it is preferable to use a rotary tool 6 having a probe diameter P whose length is different from the recess width G. In the example shown in the figure, a rotary tool 6 having a probe diameter P longer than the recess width G is used. However, without being limited to such a configuration, a rotary tool 6 having a probe diameter P whose length is equal to or shorter than the recess width G may be used. For example, when closing the groove 44A in one pass as described above, a rotary tool 6 having a probe diameter P whose length is approximately the same as the recess width G can be used. Furthermore, when closing the groove 44A in two passes as described above, a rotary tool 6 having a probe diameter P whose length is approximately half the recess width G can be used.

[0043] As shown in Figures 1 and 6 to 8, the hollow metal member 1 obtained through these processes comprises a main body 2 in which an internal space 21 is formed, and a closing portion 3 formed on the surface side of the main body 2 relative to the internal space 21. The main body 2 originates from the metal member 41 of the grooved metal member 46A. That is, the metal member 41 of the grooved metal member 46A subjected to the closing process becomes the main body 2 of the hollow metal member 1 that is finally obtained. The internal space 21 originates from the groove portion 44A of the grooved metal member 46A. That is, the groove portion 44A of the grooved metal member 46A subjected to the closing process, excluding the portion that is closed by the metal material that has softened and flowed in the closing process, becomes the internal space 21 of the hollow metal member 1 that is finally obtained.

[0044] As described above, in the preparation step, grooved metal members 46A having grooves 44A of various shapes can be prepared by casting, cutting, or the like. Therefore, by forming the grooves 44A of the grooved metal member 46A into the desired shape, it is possible to obtain a hollow metal member 1 having an internal space 21 of the desired shape. For example, a hollow metal member 1 having an internal space 21 extending in two directions, the X direction and the Z direction, can be obtained from a grooved metal member 46A having grooves 44A with a depth longer than the probe length Q of the rotary tool 6 (for example, 2 times, 3 times, 10 times, or even more).

[0045] The blocking portion 3 is disposed offset outward with respect to the internal space 21. That is, the blocking portion 3 is disposed offset on the opposite side of the center of the internal space 21 in the width direction (Y direction). The blocking portion 3 is disposed offset outward in the width direction (Y direction) with respect to the inner wall surface of the internal space 21 (the inner surface corresponding to the reference inner surface 51 described above). The blocking portion 3 is formed at a position offset in the Y direction with respect to the internal space 21 so as to extend along the X direction, which is the extension direction of the internal space 21. When viewed from the Z direction, the blocking portion 3 is formed in the shape of an elongated oval that generally corresponds to the movement trajectory of the shoulder 61 of the rotary tool 6. The blocking portion 3 is made of a metal material that has been softened once by friction stirring in the blocking process and then re-hardened.

[0046] The blocking portion 3 of this embodiment is mainly composed of particles having a smaller crystal size than the metal material that constitutes the main body portion 2. The average particle size of the metal material that constitutes the main body portion 2 is on the order of millimeters to submillimeters, while the average particle size of the metal material that constitutes the blocking portion 3 is on the order of microns to subnano.

[0047] Furthermore, the blocking portion 3 of this embodiment has a recessed portion 31 near one end of the internal space 21 in the X direction. This recessed portion 31 has an inner surface shape that corresponds to the outer shape of the probe 62 of the rotary tool 6. In this embodiment, the recessed portion 31 has an inner surface shape that is cylindrical. This recessed portion 31 is formed with a bottom and does not communicate with the internal space 21. The depth of the recessed portion 31 is equal to the probe length Q of the rotary tool 6.

[0048] Furthermore, the blocking portion 3 of this embodiment has a minute recess 32 that extends linearly from the recess 31 along the X direction. This minute recess 32 is formed so as to follow the movement trajectory of the probe 62 of the rotary tool 6 when viewed from the Z direction. The minute recess 32 is formed as a shallow groove that is slightly recessed from the upper surface of the blocking portion 3. The depth of the minute recess 32 is shallower than the depth of the recess 31 (shorter than the probe length Q of the rotary tool 6). In this embodiment, the depth of the minute recess 32 is shallower than half the depth of the recess 31, and in the illustrated example, is even shallower than ¼ of the depth of the recess 31.

[0049] Second Embodiment A second embodiment of a hollow metal member 1 and a method for manufacturing the same (a method for manufacturing a hollow metal member) will be described with reference to the drawings. In this embodiment, the specific configuration of the hollow metal member 1 differs from that of the first embodiment, and accordingly, the specific configuration of the recessed metal member 46, which is its raw material, differs from that of the first embodiment. Below, the hollow metal member 1 and the method for manufacturing the same of this embodiment will be described, focusing mainly on the differences from the first embodiment. Note that points that are not specifically mentioned are the same as those of the first embodiment, and the same reference numerals will be used, and detailed description will be omitted.

[0050] The hollow metal member 1 of this embodiment is a part of a case member 95 (see FIG. 9 ) used in, for example, a vehicle drive device, etc., and which contains a rotating electric machine, a transmission mechanism, etc. The case member 95 is formed in a block shape using a metal material, and has a flow path 96 formed therein through which a fluid such as lubricating oil or cooling water flows. The hollow metal member 1 is used as a base material for the case member 95, and the flow path 96 forms the internal space 21.

[0051] In this embodiment, the hollow metal member 1 is also manufactured using friction stir processing (FSP). That is, in the hollow metal member manufacturing method of this embodiment, a rotary tool 6 that rotates at high speed is used to manufacture the hollow metal member 1 through a stage in which material softened by frictional heat is stirred by plastic flow. The hollow metal member manufacturing method includes a step of preparing a recessed metal member 46 (preparation step) and a step of closing the recesses 44 formed in the recessed metal member 46 (closing step).

[0052] In the preparation step, a recessed metal member 46 is prepared, in which a recess 44 is formed from the surface to the interior of a metal member 41. In this embodiment, the preparation step prepares a perforated metal member 46B, in which a hole 44B having a predetermined diameter and extending in the depth direction is formed from the surface to the interior of the metal member 41, as shown in Fig. 10. The perforated metal member 46B as in this embodiment may be formed by drilling a metal member 41 as a base.

[0053] The shape of the hole 44B in the perforated metal member 46B is determined according to the shape of the internal space 21 (flow path 96) of the hollow metal member 1 to be finally obtained. That is, the shape of the hole 44B is determined so as to encompass the shape of the desired internal space 21 (flow path 96) and to have a shape that extends in one direction so as to open to the surface (opening surface 42) of the metal member 41. In the example shown in FIG. 10, the perforated metal member 46B has a circular hole 44B that has the same shape as the desired internal space 21 (flow path 96) and extends in the Z direction to reach the opening surface 42. In this example, the Z direction is the depth direction of the hole 44B.

[0054] In the closing step, the hole 44B is closed by a friction stir process (FSP) on the holed metal member 46B. The friction stir process (FSP) is performed using a friction stir apparatus equipped with a rotary tool 6 of standard specifications, similar to the first embodiment.

[0055] In the closing process, the rotary tool 6 is rotated at high speed and pressed against a position adjacent to the hole 44B on the opening surface 42 of the holed metal member 46B. In this embodiment, the rotary tool 6 is pressed against a position on the opening surface 42 of the holed metal member 46B that is adjacent to (offset from) the hole 44B in the radial direction of the hole 44B. This causes frictional heat to locally increase the temperature of the metal material that makes up the holed metal member 46B, softening it, and the probe 62 penetrates into the holed metal member 46B. At this time, the probe 62 penetrates into the holed metal member 46B until the lower surface of the shoulder 61 comes into contact with the opening surface 42 of the holed metal member 46B.

[0056] Next, while maintaining this state, as shown in FIG. 11 , the rotary tool 6 is moved relatively along a position adjacent to the hole 44B on the opening surface 42 of the holed metal member 46B. That is, with the probe 62 inserted into the holed metal member 46B until the lower surface of the shoulder 61 contacts the opening surface 42, the rotary tool 6 is moved relatively along a position adjacent to the hole 44B on the opening surface 42 of the holed metal member 46B while rotating at high speed. In this embodiment, the rotary tool 6 is moved relatively along a trajectory parallel to the opening edge of the hole 44B at a position radially outward from the opening edge of the hole 44B on the opening surface 42 of the holed metal member 46B. As a result, the metal material constituting the holed metal member 46B gradually softens due to frictional heat and flows toward the opening surface 42 of the hole 44B, and the hole 44B is blocked by the softened material.

[0057] Thus, in the closing process, the rotary tool 6 is moved (relatively moved) along a large-diameter circular path that is concentric with the opening edge over the entire circumference of the hole 44B while being pressed against the opening surface 42 of the holed metal member 46B. In the closing process, the rotary tool 6 is moved in a circular shape along the opening edge over the entire circumference of the hole 44B. Then, in the closing process, the hole 44B is closed with the softened material on the opening surface 42.

[0058] 12, the radial offset of the rotary tool 6 with respect to the hole 44B is preferably set to satisfy the following condition: In this embodiment, the inner surface of the hole 44B itself is the reference inner surface 51 of the recess 44.

[0059] It is preferable that the offset of the rotary tool 6 is set so that the ratio (offset ratio (F / P)) of the offset width F from the reference inner surface 51 of the recess 44 (hole 44B) to the rotation axis A of the rotary tool 6 to the probe diameter P is between 0 and 1. It is also preferable that the offset of the rotary tool 6 is set so that the ratio (machining allowance ratio (R / P)) of the processing allowance R to the probe diameter P is between 0.5 and 1.5.

[0060] In this embodiment, it is sufficient if the hole 44B is entirely closed when the rotary tool 6 is rotated once along a circular locus concentric with the hole 44B. In this case, the offset width F is preferably set within a range in which the shoulder 61 of the rotary tool 6 covers the center of the hole 44B, and more quantitatively, it is preferably set to half the difference between the shoulder diameter S and the recess width G (F≦0.5(SG)). In this embodiment, the recess width G is the diameter of the hole 44B (hereinafter referred to as the "hole diameter Gb"), and the offset width F is preferably set to half the difference between the shoulder diameter S and the hole diameter Gb (F≦0.5(S-Gb)).

[0061] As shown in FIG. 13 , the hollow metal member 1 obtained through these steps includes a main body 2 having an internal space 21 (flow path 96) formed therein, and a blocking portion 3 formed on the surface side of the main body 2 relative to the internal space 21 (flow path 96). The blocking portion 3 is disposed offset outward relative to the internal space 21 (flow path 96). That is, the blocking portion 3 is disposed offset from the center of the internal space 21 (flow path 96) relative to the internal space 21 (flow path 96). The blocking portion 3 is disposed offset radially outward relative to the inner wall surface of the internal space 21 (flow path 96) (the inner surface corresponding to the reference inner surface 51 described above). Furthermore, the blocking portion 3 is formed with a larger diameter than the internal space 21 (flow path 96) and is disposed concentrically with the internal space 21 (flow path 96). Thus, in this embodiment, even if the blocking portion 3 is concentric overall, being offset outward at each circumferential position is one aspect of “the blocking portion 3 being disposed offset outward relative to the inner wall surface of the internal space 21.”

[0062] The blocking portion 3 is made of a metal material that has been softened by friction stirring in the blocking process and then re-hardened. The blocking portion 3 is mainly made of particles with smaller crystal size than the metal material that makes up the main body 2.

[0063] The blocking portion 3 of this embodiment also has a recess 31 at one location in the circumferential direction. This recess 31 has an inner surface shape that corresponds to the outer shape of the probe 62 of the rotary tool 6. This recess 31 is formed with a bottom and does not communicate with the internal space 21 (flow path 96). The blocking portion 3 of this embodiment also has a minute recess 32 that extends annularly from the recess 31 along the circumferential direction of the internal space 21 (flow path 96). This minute recess 32 is formed so as to follow the movement trajectory of the probe 62 of the rotary tool 6 when viewed from the Z direction. The minute recess 32 is formed in the shape of a shallow groove that is slightly recessed from the upper surface of the blocking portion 3. The depth of the minute recess 32 is shallower than the depth of the recess 31.

[0064] Third Embodiment A third embodiment of a hollow metal member 1 and a method for manufacturing the same (a method for manufacturing a hollow metal member) will be described with reference to the drawings. In this embodiment, the specific configuration of the rotary tool 6 provided in the friction stirring device used in the closing step differs from that of the first embodiment, and accordingly, the specific configuration of the hollow metal member 1 finally obtained also differs from that of the first embodiment. Below, the hollow metal member 1 and the method for manufacturing the same of this embodiment will be described, focusing mainly on the differences from the first embodiment. Note that points that are not specifically mentioned are the same as those in the first embodiment, and the same reference numerals will be used, and detailed description will be omitted.

[0065] The rotary tool 6 used in this embodiment is similar to that of the first embodiment in that it includes a cylindrical shoulder 61 and a probe 62 integrated and coaxially therewith, but the specific configuration of the probe 62 differs from that of the first embodiment. As shown in Figures 14 to 16, the probe 62 of this embodiment has a spiral portion 63 continuing from the shoulder 61 and a receiving portion 64 provided at the tip of the spiral portion 63. The receiving portion 64 has a narrowed portion 64A, a receiving main body portion 64B, and a sharpened portion 64C.

[0066] 14 to 16, the maximum diameter of helical portion 63 (hereinafter referred to as "helix diameter") is designated as "H," the difference in height of one revolution of helical portion 63 (hereinafter referred to as "helix pitch") is designated as "J," and the difference in radius of one revolution of helical portion 63 (hereinafter referred to as "helix width") is designated as "K." Furthermore, the diameter of constricted portion 64A (hereinafter referred to as "constriction diameter") is designated as "N," and the length of constricted portion 64A (the length between the lower end of helical portion 63 and receiving main body portion 64B; hereinafter referred to as "constriction length") is designated as "M." Furthermore, the diameter of receiving main body portion 64B (hereinafter referred to as "receiving diameter") is designated as "T," and the length of receiving main body portion 64B (hereinafter referred to as "receiving length") is designated as "U." In addition, the angle between an imaginary line connecting the outermost points at each position of the spiral portion 63 and a horizontal plane (hereinafter referred to as the "spiral angle") is "α", and the angle between the outer surface of the sharp portion 64C and the horizontal plane (hereinafter referred to as the "tip angle") is "β".

[0067] The spiral portion 63 is a portion that functions as a substantial portion of the probe 62 (i.e., a portion that frictionally stirs material when the rotary tool 6 rotates at high speed). The spiral portion 63 is formed so as to describe a spiral in the axial direction of the shoulder 61, gradually decreasing in diameter as it moves away from the shoulder 61 (toward the tip of the probe 62). The spiral portion 63 is formed from a position slightly radially inward from the outer surface of the shoulder 61. The spiral diameter H is set to be smaller than the shoulder diameter S. The ratio of the spiral diameter H to the shoulder diameter S (H / S) is not particularly limited, but may be, for example, 0.7 to 0.95, or 0.75 to 0.85.

[0068] The spiral portion 63 is formed to draw a spiral with a substantially constant width. The spiral width K is set to a substantially constant value. The ratio (K / H) of the spiral width K to the spiral diameter H is not particularly limited, but may be, for example, 0.05 to 0.2, or 0.1 to 0.15.

[0069] The helical portion 63 is formed so as to draw a spiral at a substantially constant pitch. The helical pitch J is set to a substantially constant value. The ratio (J / K) of the helical pitch J to the helical width K is not particularly limited, but may be, for example, 0.2 to 0.8, or 0.3 to 0.6.

[0070] The helical angle α is not particularly limited, but may be, for example, 22.5° or more and 60° or less, or 30° or more and 45° or less.

[0071] The receiving portion 64 is provided at the tip of the spiral portion 63 so as to receive from below the material that has been softened by friction stirring by the spiral portion 63. The receiving portion 64 is provided with a constricted portion 64A, a receiving main body portion 64B, and a sharp portion 64C, in this order from the shoulder 61 side (the spiral portion 63 side) toward the tip side.

[0072] The constricted portion 64A is located in the middle of the probe 62 and is formed to be thinner than other portions. The constricted portion 64A is formed to be slightly thinner than the lower end of the spiral portion 63. The constricted diameter N is not particularly limited, but may be, for example, 3 mm to 6 mm, or 4 mm to 5 mm. The constricted length M is not particularly limited, but may be, for example, 0.5 mm to 2.5 mm, or 0.8 mm to 1.8 mm.

[0073] The ratio (N / H) of the neck diameter N to the spiral diameter H is not particularly limited, but may be, for example, 0.1 to 0.3, or 0.15 to 0.25. The ratio (M / Q) of the neck length M to the probe length Q is not particularly limited, but may be, for example, 0.05 to 0.2, or 0.08 to 0.15. Furthermore, the ratio (M / N) of the neck length M to the neck diameter N is not particularly limited, but may be, for example, 0.1 to 0.25, or 0.15 to 0.2.

[0074] The receiving body portion 64B is a portion that functions as the substantial portion of the receiving portion 64 (i.e., a portion that receives the softened material from below). The receiving body portion 64B is formed in a flat cylindrical shape. The receiving diameter T is not particularly limited, but is preferably equal to or slightly smaller than the recess width G of the recess 44 of the recessed metal member 46 (in this embodiment, the groove width Ga of the groove portion 44A of the grooved metal member 46A) (see FIG. 17). The ratio of the receiving length U to the probe length Q (U / Q) is not particularly limited, but may be, for example, 0.2 to 0.4, or 0.25 to 0.3. The ratio of the receiving length U to the receiving diameter T (U / T) is not particularly limited, but may be, for example, 0.1 to 0.5, or 0.2 to 0.4.

[0075] The sharp tip portion 64C is a pointed portion on the tip side of the receiving portion 64. The sharp tip portion 64C is formed in a flat inverted cone shape so that the diameter gradually decreases toward the tip side (away from the receiving main body portion 64B). The sharp tip portion 64C functions as a guide portion that aligns the center of the rotary tool 6 when it is deviated from the center of the recess 44 (groove portion 44A in this embodiment) in the Y direction. The tip angle β is not particularly limited, but may be, for example, equal to or less than the helix angle α. The tip angle β may be, for example, 7.5° to 30°, or 10° to 20°.

[0076] In this embodiment, a friction stir welding apparatus including the specially specified rotary tool 6 described above is used in the closing step, and the rotary tool 6 is moved relatively along the center line C of the opening of the recess 44 (groove 44A) as shown in FIGS. 17 and 18 . That is, with the receiving portion 64 entering the recess 44 (groove 44A) and the spiral portion 63 in contact with the upper surface of the recessed metal member 46 (grooved metal member 46A), the rotary tool 6 is moved relatively along the center line C of the opening of the recess 44 (groove 44A) while rotating at high speed. As a result, the metal material constituting the grooved metal member 46A gradually softens due to frictional heat and flows toward the opening surface 42 of the groove 44A, and is received from below by the receiving portion 64, and the groove 44A is closed with the softened material.

[0077] 19 and 20, in this embodiment, an escape hole 48 is formed in the recessed metal member 46 (grooved metal member 46A) at a position adjacent to the X-direction end of the recess 44 (groove 44A). In the illustrated example, the escape hole 48 is provided at a position further adjacent in the X-direction to the X-direction end of the recess 44 (groove 44A), but if there is space in the Y direction, the escape hole 48 may be shifted in the Y direction. The inner diameter and depth of the escape hole 48 are set so as not to interfere with the probe 62 (particularly the receiving portion 64) of the rotary tool 6.

[0078] In this embodiment, since the rotary tool 6 has the receiving portion 64, when the rotary tool 6 is raised and removed from the recessed metal member 46 (grooved metal member 46A) in the final stage of the closing step, it is inevitable that a sinkhole will be formed according to the outer shape of the receiving portion 64. Even in such a case, by moving the rotary tool 6 to the position of the relief hole 48 in the final stage of the closing step and then removing it, it is possible to prevent the internal space 21 of the hollow metal member 1 that is finally obtained from unintentionally communicating with the outside due to the inevitably occurring sinkhole.

[0079] As shown in Figures 19 and 20, the hollow metal member 1 obtained in this embodiment comprises a main body 2 in which an internal space 21 is formed, and a blocking portion 3 formed on the surface side of the main body 2 relative to the internal space 21. The origin of the main body 2 and the origin of the internal space 21 are the same as in the first embodiment. Also, similar to the first embodiment, the blocking portion 3 is mainly composed of particles with a smaller crystal size than the metal material that constitutes the main body 2.

[0080] In this embodiment, the closing portion 3 has a bottom surface 34 and a tapered surface 35. The bottom surface 34 is formed in a shape corresponding to the recess 44 (groove portion 44A) of the recessed metal member 46 (grooved metal member 46A). The bottom surface 34 is provided at a position slightly below the upper surface of the hollow metal member 1. The tapered surface 35 is inclined gradually upward from the bottom surface 34 toward the outside. Such tapered surfaces 35 inclined upward toward the outside are provided on both sides of the center line C of the internal space 21 in the Y direction and on both sides of the internal space 21 in the X direction. The tapered surfaces 35 are formed around the bottom surface 34 so as to surround the entire periphery of the bottom surface 34.

[0081] In this embodiment, as shown in FIG. 21 , the closing portion 3 has a tool mark 37 on its back surface (i.e., the surface facing the internal space 21). This tool mark 37 is a mark made by the rotary tool 6 moving while rotating, and more specifically, a mark made on the back surface of the bottom surface 34 by the receiving portion 64 moving while rotating. In this embodiment, the tool mark 37 is a mark made by a plurality of arc-shaped curves connected at approximately equal intervals in the X direction. In this way, when viewing the closing portion 3 from the internal space 21 side, the fact that the tool mark 37 made by the rotary tool 6 moving while rotating can be confirmed is one of the features of the hollow metal member 1 of this embodiment.

[0082] Other Embodiments (1) In each of the above embodiments, a configuration has been described as an example in which the recesses 44 (groove portions 44A / hole portions 44B) of the recessed metal member 46 are open only on a single surface. However, the present invention is not limited to such a configuration, and the recesses 44 of the recessed metal member 46 may be open on multiple surfaces. In this case, in the closing step, friction stir processing (FSP) is performed on each of the multiple open surfaces 42, and the recesses 44 are closed by the cooperation of the multiple closing portions 3.

[0083] (2) In the above embodiments, the cooling member 90 using the hollow metal member 1 and the case member 95 are mainly described as separate components. However, the present invention is not limited to such a configuration, and the cooling member 90 using the hollow metal member 1 and the case member 95 may be integrated into one body. Alternatively, one or both of the cooling member 90 and the case member 95 may be integrated into one body with another component.

[0084] (3) In each of the above embodiments, the recesses 44 formed in the recessed metal member 46 are grooves 44A extending in the longitudinal direction or holes 44B extending in the depth direction. However, the recesses 44 are not limited to such configurations, and may be formed in more complex shapes, such as an L-shape, a T-shape, a crank shape, or a serpentine shape.

[0085] (4) The configurations disclosed in the above-described embodiments (including the above-described embodiments and other embodiments; the same applies hereinafter) can be applied in combination with configurations disclosed in other embodiments, as long as no contradiction occurs. Regarding other configurations, the embodiments disclosed in this specification are illustrative in all respects and can be appropriately modified within the scope of the present disclosure.

[0086] [Outline of the embodiment] To summarize the above, the method for manufacturing a hollow metal member according to the present disclosure preferably includes the following configurations.

[0087] A method for manufacturing a hollow metal member (1), which is a metal member (41) having an internal space (21), using a rotary tool (6), comprising the steps of: a step of preparing a recessed metal member (46) having a recess (44) corresponding to a desired internal space shape formed from the surface to the interior of the metal member (41); a step of moving the rotary tool (6) along the opening of the recess (44) while pressing the rotary tool (6) against an opening surface (42) on which the recess (44) is formed in the recessed metal member (46), and closing the recess (44) with the softened material on the opening surface (42); Includes.

[0088] According to this configuration, the rotary tool 6 is pressed against the opening surface 42 of the recessed metal member 46, which has a recess 44 shaped according to the desired internal space shape extending from the surface to the interior of the metal member 41, regardless of the shape of the rotary tool 6. The rotary tool 6 is then moved along the opening of the recess 44. This allows the recess 44 to be closed with softened material using a friction stir process (FSP). This allows the hollow metal member 1 to be formed while ensuring freedom in the shape of the internal space 21.

[0089] In one embodiment, In the step of closing the recess (44), the rotary tool (6) is preferably moved along the opening edge of the recess (44).

[0090] This configuration makes it easy for the opening of the recess 44 to be blocked by the material softened by the friction stir process (FSP), and therefore, it is possible to appropriately form the hollow metal member 1 with a high degree of freedom in the shape of the internal space 21 using a rotary tool 6 with standard specifications that is widely used for the friction stir process (FSP).

[0091] In one embodiment, In the step of closing the recess (44), it is preferable to move the rotary tool within a range in which the ratio of an offset width (F) along the opening surface (42) from a reference inner surface (51) of the recess (44) to a rotation axis (A) of the rotary tool (6) to a diameter (P) of the probe (62) of the rotary tool (6) is greater than or equal to 0 and less than 1.

[0092] By setting the ratio of the offset width (F) from the reference inner surface (51) of the recess (44) to the rotation axis (A) of the rotary tool (6) to the probe diameter (P) of the rotary tool (6) (hereinafter referred to as the "offset ratio") to be 0 or greater, a sufficient amount of material can be softened by the friction stir process (FSP). Furthermore, by setting the offset ratio to be 1 or less, it is possible to ensure that the material softened by the friction stir process (FSP) flows to the opening surface (42) of the recess (44). Therefore, with this configuration, the opening surface (42) of the recess (44) can be appropriately blocked with the softened material using the friction stir process (FSP).

[0093] In one embodiment, The recess (44) is a groove (44A) extending along the longitudinal direction (X), It is preferable that the offset width (F) is set within a range in which the shoulder (61) of the rotary tool (6) covers the inner surface (52) of the groove portion (44A) opposite to the reference inner surface (51).

[0094] According to this configuration, the open surface 42 of the groove 44A can be closed in a single process along a position adjacent to the groove 44A formed in the recessed metal member 46. Therefore, the hollow metal member 1 can be formed efficiently.

[0095] In one embodiment, The recess (44) is a groove (44A) extending along the longitudinal direction (X), In the step of closing the recess (44), it is preferable that the rotary tool (6) is moved linearly along at least one opening edge of the groove (44A) along the longitudinal direction (X).

[0096] According to this configuration, when the recess (44) is a groove (44A) extending along the longitudinal direction (X), the groove (44A) can be appropriately closed in the step of closing the recess (44).

[0097] In one embodiment, The recess (44) is a hole (44B) extending along the depth direction (Z), In the step of closing the recess (44), the rotary tool (6) is preferably moved in a circular shape along the opening edge of the hole (44B) over the entire circumference.

[0098] According to this configuration, when the recess (44) is a hole (44B) extending in the depth direction (Z), the hole (44B) can be appropriately closed in the step of closing the recess (44).

[0099] In one embodiment, In the step of closing the recess (44), it is preferable to move the rotary tool (6) along the center line (C) of the opening of the recess (44).

[0100] According to this configuration, even if a sufficient thickness is not ensured at one position adjacent to the recess 44 in the metal member 41, the opening of the recess 44 can be closed with material softened by the friction stir process (FSP) by using the specially designed rotary tool 6. Therefore, it is possible to appropriately form a hollow metal member 1 in which the internal space 21 is well-balanced in the width direction Y and the degree of freedom in shape is ensured.

[0101] The present specification also discloses an article (hollow metal member (1)) manufactured by the above-mentioned hollow metal member manufacturing method. Such a hollow metal member (1) preferably has the following configuration.

[0102] A hollow metal member (1) having an internal space (21), a main body portion (2) in which the internal space (21) of a desired shape is formed; a blocking portion (3) formed along the internal space (21) in a portion of the main body portion (2) on the surface side of the internal space (21), the blocking portion (3) being mainly made of particles having a smaller crystal size than the constituent material of the main body portion (2), The closing portion (3) is disposed offset outward from the inner wall surface of the internal space (21).

[0103] According to this configuration, the blocking portion (3) can be formed in the portion of the main body (2) closer to the surface than the internal space (21) by using friction stir processing (FSP). The process of forming the space that will become the internal space (21) in the metal member and the process of forming the blocking portion (3) can be separated, so the internal space (21) can be formed with a sufficient degree of freedom in shape. Furthermore, by disposing the blocking portion (3) offset outward from the inner wall surface of the internal space (21), the portion closer to the surface than the internal space (21) can be appropriately blocked when the blocking portion (3) is formed by using friction stir processing (FSP). This results in a hollow metal member (1) having an internal space (21) of the desired shape.

[0104] This specification also discloses a special tool (rotary tool 6) used to manufacture the above-mentioned hollow metal member 1. Such a rotary tool 6 preferably has the following configuration.

[0105] A rotary tool (6) for manufacturing a hollow metal member (1), which is a metal member (41) having an internal space (21), A cylindrical shoulder (61) and a probe (62) coaxially integrated with the shoulder (61), The probe (62) has a spiral portion (63) whose diameter decreases as it moves away from the shoulder (61) in the axial direction of the shoulder (61), and a receiving portion (64) provided at the tip of the spiral portion (63) so as to receive the material that has been stirred and softened by the spiral portion (63) from below.

[0106] According to this configuration, the spiral portion 63 of the probe 62 frictionally stirs the material, causing the softened material to flow near the opening of the recess 44. The probe 62 has a receiving portion 64 at the tip of the spiral portion 63, so the softened material is received from below by the receiving portion 64 and does not flow deep into the recess 44. Therefore, the recess 44 can be closed while the rotary tool 6 is moved along the center line C of the opening of the recess 44. Therefore, by using the rotary tool 6 of this configuration, a hollow metal member 1 can be appropriately manufactured, in which the internal space 21, which ensures freedom in shape, is well-balanced in the width direction Y.

[0107] The hollow metal member (1) formed using the specially designed rotary tool (6) described above is A hollow metal member (1) having an internal space (21), a main body portion (2) in which the internal space (21) of a desired shape is formed; a blocking portion (3) formed along the internal space (21) in a portion of the main body portion (2) on the surface side of the internal space (21), the blocking portion (3) being mainly made of particles having a smaller crystal size than the constituent material of the main body portion (2), The closing portion (3) has tapered surfaces (35) that are inclined upwards toward the outside on both sides in the width direction (Y) across the center line (C) of the internal space (21).

[0108] Another hollow metal member (1) formed using the specially designed rotary tool (6) described above is A hollow metal member (1) having an internal space (21), a main body portion (2) in which the internal space (21) of a desired shape is formed; a blocking portion (3) formed along the internal space (21) in a portion of the main body portion (2) on the surface side of the internal space (21), the blocking portion (3) being mainly made of particles having a smaller crystal size than the constituent material of the main body portion (2), The closing portion (3) has a tool mark (37) on the back surface facing the internal space (21) that is formed by the rotary tool (6) moving while rotating.

[0109] It is sufficient for the hollow metal member manufacturing method, hollow metal member, and rotary tool according to the present disclosure to achieve at least one of the above-described effects. [Explanation of symbols]

[0110] 1: hollow metal member, 2: main body, 3: closing portion, 6: rotating tool, 21: internal space, 31: recessed portion, 32: minute recessed portion, 34: bottom surface, 35: tapered surface, 37: tool mark, 41: metal member, 42: opening surface, 44: recess, 44A: groove portion, 44B: hole portion, 46: recessed metal member, 46A: grooved metal member, 46B: holed metal member, 48: relief hole, 51: reference inner surface, 52: opposing inner surface, 61: shoulder, 62: probe, 63: spiral portion, 64: receiving portion, 64 A: constricted portion, 64B: receiving body portion, 64C: sharp portion, 90: cooling member, 91: flow path space, 92: inlet, 93: outlet, 95: case member, 96: flow path, A: rotation axis, C: center line, F: offset width, G: recess width, Ga: groove width, Gb: hole diameter, H: spiral diameter, J: spiral pitch, K: spiral width, M: constricted length, N: constricted diameter, P: probe diameter, Q: probe length, R: machining allowance, S: shoulder diameter, T: receiving diameter, U: receiving length, α: spiral angle, β: tip angle

Claims

1. A method for manufacturing a hollow metal member, which is a metal member having an internal space, using a rotary tool, comprising: a step of preparing a recessed metal member having a recess corresponding to a desired internal space shape formed from the surface to the interior of the metal member; a step of moving the rotary tool along the opening of the recess while pressing it against an opening surface, which is the surface on which the recess is formed in the recessed metal member, and closing the recess with the softened material on the opening surface; A method for manufacturing a hollow metal member, comprising:

2. The method for manufacturing a hollow metal member according to claim 1 , wherein in the step of closing the recess, the rotary tool is moved along an edge of an opening of the recess.

3. 3. The hollow metal member manufacturing method according to claim 2, wherein in the step of closing the recess, the rotary tool is moved within a range in which the ratio of the offset width along the opening surface from the reference inner surface of the recess to the rotation axis of the rotary tool to the diameter of the probe of the rotary tool is greater than or equal to 0 and less than 1.

4. The recess is a groove extending along the longitudinal direction, The method for manufacturing a hollow metal member according to claim 2 or 3, wherein in the step of closing the recess, the rotary tool is moved linearly along at least one opening edge along the longitudinal direction of the groove.

5. The recess is a hole extending in a depth direction, The method for manufacturing a hollow metal member according to claim 2 or 3, wherein in the step of closing the recess, the rotary tool is moved in a circular shape along an opening edge over the entire circumference of the hole.

6. The method for manufacturing a hollow metal member according to claim 1 , wherein in the step of closing the recess, the rotary tool is moved along a center line of the opening of the recess.

7. A hollow metal member having an internal space, a main body portion in which the internal space of a desired shape is formed; a blocking portion formed along the internal space on a surface side of the main body portion with respect to the internal space, the blocking portion being mainly made of particles having a smaller crystal size than the constituent material of the main body portion, The hollow metal member, wherein the closing portion is disposed offset outward relative to the inner wall surface of the internal space.

8. A hollow metal member having an internal space, a main body portion in which the internal space of a desired shape is formed; a blocking portion formed along the internal space on a surface side of the main body portion with respect to the internal space, the blocking portion being mainly made of particles having a smaller crystal size than the constituent material of the main body portion, The closing portion has tapered surfaces that slope upward outward on both sides in the width direction across the center line of the internal space, the hollow metal member.

9. A hollow metal member having an internal space, a main body portion in which the internal space of a desired shape is formed; a blocking portion formed along the internal space on a surface side of the main body portion with respect to the internal space, the blocking portion being mainly made of particles having a smaller crystal size than the constituent material of the main body portion, The closing portion has a tool mark on a back surface facing the internal space, the tool mark being caused by a rotary tool moving while rotating.

10. A rotary tool for manufacturing a hollow metal member, which is a metal member having an internal space, comprising: a cylindrical shoulder and a probe coaxially integrated with the shoulder; The probe has a spiral portion whose diameter decreases as it moves away from the shoulder in the axial direction of the shoulder, and a receiving portion provided at the tip of the spiral portion so as to receive from below the material that has been stirred and softened by the spiral portion.

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