METHOD FOR MANUFACTURING A HOLLOW METAL PART, HOLLOW METAL PART AND TURNING TOOL

Abstract

A method for producing a hollow metal component (1), which is a metal component (41) with an interior (21), using a rotary tool (6), comprises: a step for providing a recessed metal component (46) in which a recessed part (44) corresponding to a desired interior shape is formed from a surface to an interior of the metal component; and a step for moving the rotary tool along an opening of the recessed part while the rotary tool is pressed against an opening surface (42) which is a surface of the recessed metal component on which the recessed part is formed, and closing the recessed part with a softened material of the opening surface.

Description

TECHNICAL FIELDThis disclosure relates to a method of manufacturing a hollow metal component.BACKGROUNDFor example, in order to form a member having a space therein through which a liquid or a gas passes, a hollow metal member that is a metal member having an inner space may be manufactured. As a method for manufacturing the hollow metal member, a method using friction stir processing (FSP) is known.An example of the method for manufacturing a hollow metal member using friction stir machining (FSP) is disclosed in JP 2014-223 680 A (Reference 1). In the method of JP 2014-223 680 A (Reference 1), using a turning tool, the turning tool is moved along a surface of the metal member while being turned, a flat groove part is formed, and at the same time, the groove part is covered by a lid to form a tunnel-like inner space in the metal member.However, the method of Reference 1 has a problem that a shape of the internal space formed in the hollow metal member is limited by a shape of the turning tool.Thus, there is a need for a method of manufacturing a hollow metal member for manufacturing a hollow metal member in which the degree of freedom of the shape of the internal space is secured.SUMMARYA method for manufacturing a hollow metal member according to the disclosure for manufacturing a hollow metal member, which is a metal member having an internal space, using a turning tool includes: a step of providing a metal member provided with a recess in which a recessed part corresponding to a desired internal space shape is formed from a surface to an inside of the metal member; and a step of moving the turning tool along an opening of the recessed part while pressing the turning tool against an opening surface, which is a surface of the metal member provided with a recess on which the recessed part is formed, and closing the recessed part with a softened material of the opening surface.According to this configuration, the turning tool is moved along the opening of the recessed part while the turning tool is pressed against the opening surface of the metal member provided with a recess, in which the recessed part is formed with a shape corresponding to the desired inner space shape regardless of a shape of the turning tool from the surface to the inside of the metal member. Thus, the recessed portion can be closed by the deposited material using friction stir machining (FSP). Therefore, the hollow metal member can be formed while ensuring a degree of freedom of a shape of the internal space.BRIEF DESCRIPTION OF THE DRAWINGSThe above, as well as additional features and characteristics of this disclosure, will become apparent from the following detailed description with reference to the accompanying drawings. The following are shown: FIG. 1 is a perspective view of a hollow metal member according to a first embodiment; FIG. 2 is a perspective view of a metal member provided with a groove; FIG. 3 is a cross-sectional view showing an aspect of a closing step; FIG. 4 is a plan view showing an aspect of the closing step; FIG. 5 shows an offset width of a rotary tool with respect to a groove part; FIG. 6 is a plan view of the hollow metal member; FIG. 7 is a cross-sectional view taken along a line VII-VII in FIG. 6 ; FIG. 8 is a cross-sectional view taken along a line VIII-VIII in FIG. 6 ; FIG. 9 is a plan view of a metal member provided with a hole according to a second embodiment; FIG. 10 is a cross-sectional view of the perforated metal member; FIG. 11 is a plan view showing an aspect of a closing step; FIG. 12 is an offset width of a rotary tool with respect to a hole part; FIG. 13 is a plan view of a hollow metal member; FIG. 14 is a schematic front view of a fixed tool used in a third embodiment; FIG. 15 is a partially enlarged view of FIG. 14 ; FIG. 16 is a schematic bottom view of the fixed tool; FIG. 17 is a cross-sectional view showing an aspect of a closing step; FIG. 18 is a plan view showing an aspect of the closing step; FIG. 19 is a perspective view of a hollow metal member; FIG. 20 is a cross-sectional view of the hollow metal member; and FIG. 21 is a photograph showing a state of a closure member as viewed from an interior side.DETAILED DESCRIPTIONFirst EmbodimentA hollow metal member 1 and a method of manufacturing the same (a method of manufacturing a hollow metal member) according to a first embodiment will be described with reference to the drawings.The hollow metal member 1 according to the embodiment is a part of a cooling member 90 that constitutes a cooling device together with, for example, a cooling circuit and a pump. The cooling member 90 is formed in a piece shape using a metal material, and as shown in FIG. 1, includes a flow path space 91 in which a coolant flows, and an inflow opening 92 and an outflow opening 93 that connect the flow path space 91 to the outside. The cooling circuit is indirectly connected to the inflow port 92 and the outflow port 93 directly or via a connecting member or the like.The hollow metal member 1 is used as a member underlying the cooling member 90. The hollow metal member 1 is a metal member having an internal space 21, and the hollow metal member 1 includes a body part 2 and a closing part 3 formed in a part on a surface side of the body part 2. In the embodiment, the body part 2 is formed in the shape of a flat rectangular cuboid. The internal space 21 is formed in the body part 2. In the example, the internal space 21 is not formed in a simple linear shape but in a two-dimensional manner. The closing part 3 closes the internal space 21 at a part on the surface side of the body part 2.Through holes communicating with the internal space 21 are formed to form the cooling member 90 from two opposite side surfaces of the hollow metal member 1, respectively. In this case, the two through holes serve as the inflow opening 92 and the outflow opening 93, and the internal space 21 serves as the flow path space 91.In the following description, a height direction of the hollow metal member 1 in FIG. 1 is referred to as a Z direction, a longitudinal direction of the hollow metal member 1 as viewed from the Z direction is referred to as an X direction, and a lateral direction is referred to as a Y direction. The internal space 21 of the hollow metal member 1 according to the embodiment is a space extending in the X direction and the Z direction, respectively.In the method for manufacturing a hollow metal member according to the embodiment, the hollow metal member 1 is manufactured using friction stir machining (FSP). That is, in the method for manufacturing a hollow metal member according to the embodiment, the hollow metal member 1 is manufactured by a step of stirring a material softened by frictional heat by plastic flow using a rotating tool 6 rotating at a high speed.The method for manufacturing a hollow metal member includes a step of providing a recessed metal member 46 (hereinafter referred to as a "providing step") and a step of closing a recessed part 44 formed in the recessed metal member 46 (hereinafter referred to as a "closing step").In the providing step, the recessed metal member 46 in which the recessed part 44 is formed from a surface to an inside of a metal member 41 is provided. The recessed portion 44 is a portion that is recessed from the surface toward the inside of the metal member 41 and may be closed or opened regardless of the depth on the opposite side. In the embodiment, in the providing step, as shown in FIG. 2, a grooved metal member 46A in which a groove part 44A extending at a predetermined depth in the longitudinal direction is formed from the surface to the inside of the metal member 41 is provided.A metal material constituting the metal member 41 is not limited as long as it is a metal that can be processed by friction stir milling, and for example, aluminum, copper, titanium, magnesium, and an alloy thereof can be used. When used as a part of the cooling member 90 as in the embodiment, a metal having high thermal conductivity (for example, copper or aluminum) is preferable.The grooved metal member 46A as the indented metal member 46 can be formed by, for example, casting. In this case, the grooved metal member 46A is formed as the metal member 41 in which the groove part 44A is formed as the recessed part 44 from the beginning. The grooved metal member 46A can be formed as a base body by, for example, cutting the metal member 41. In this case, the grooved metal member 46A is formed by forming the groove part 44A in the metal member 41 at a later time. In either case, the grooved metal member 46A having the groove part 44A can be formed into various shapes by matching a shape of a shape or a shape of a machining.The shape of the groove part 44A of 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 groove part 44A is set to have the shape of the desired internal space 21 and is a shape extending in at least one direction for opening in the surface of the metal member 41. In the embodiment, the surface in which the groove part 44A is opened is referred to as an opening surface 42. In the example shown in FIG. 2, the grooved metal member 46A has the groove part 44A having the same shape as the desired internal space 21 and a shape extending in the Z direction until reaching the opening surface 42.That is, the groove part 44A of the grooved metal member 46A is formed to have the same size in the X direction and the Y direction as the inner space 21 of the hollow metal member 1 to be finally obtained, have a size in the Z direction larger than the inner space 21, and be opened to the surface. Referring to the groove part 44A of the grooved metal member 46A, a depth direction of the groove part 44A is the Z direction, an extending direction is the X direction, and a width direction is the Y direction.A body for forming the grooved metal member 46A may be the same as or different from a manufacturing body of the hollow metal member 1. That is, in the providing step, the manufacturing body of the hollow metal member 1 may be provided by forming the grooved metal member 46A itself or may be provided by obtaining the grooved metal member 46A formed by another body.In the closing step, the groove part 44A is closed by the friction stir machining (FSP) for the grooved metal member 46A. The friction stir machining (FSP) is performed using a friction stir apparatus including the 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 a direction of a rotation axis.In the embodiment, as the rotary tool 6, a tool having a normal specification generally used for friction stir machining (FSP) is used. As shown in FIG. 3, the rotary tool 6 has a shoulder 61 and a head (probe) 62 provided integrally with the shoulder 61. The shoulder 61 is formed with a columnar shape rotatable about a rotation axis A. The shoulder 61 is drivingly connected to the drive unit and rotates about the rotational axis A by power from the drive unit. the shoulder 61 is also drivingly connected to the pushing unit and can advance and retract along the rotational axis A.The head 62 is provided coaxially with the shoulder 61 so as to project further downward from a lower surface of the shoulder 61. The head 62 is formed in a columnar shape having a substantially constant diameter. The head 62 is formed to have a diameter smaller than the shoulder 61. The head 62 rotates about the rotation axis A by the power from the driving unit together with the shoulder 61, and the head 62 is also drivingly connected to the pushing unit and can advance and retreat together with the shoulder 61.The turning tool 6 is made of a material having high hardness, for example, high-speed tool steel, alloy tool steel, super steel alloy and ceramics.In the closing step, first, as shown in FIG. 3, the rotating tool 6 is pressed against a position adjacent to the groove part 44A of the opening surface 42 of the grooved metal member 46A while being rotated at a high speed. In the embodiment, the rotary tool 6 is pressed against a position (offset position) of the opening surface 42 of the grooved metal member 46A adjacent to the groove part 44A in the Y direction, which is the width direction of the groove part 44A. Then, the metal material forming the grooved metal member 46A is locally heated and softened by the frictional heat, and the head 62 enters an interior of the grooved metal member 46A. At this time, the head 62 enters the inside of 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.Next, as shown in FIG. 4, while maintaining this state, the turning tool 6 is relatively moved along the position adjacent to the groove part 44A of the opening surface 42 of the grooved metal member 46A. That is, in a state in which the head 62 enters the inside of the grooved metal member 46A until the lower surface of the shoulder 61 comes into contact with the opening surface 42, the turning tool 6 is relatively moved along the position adjacent to the groove part 44A of the opening surface 42 of the grooved metal member 46A while being turned at high speed. In the embodiment, at the position on the opening surface 42 of the grooved metal member 46A adjacent to the groove part 44A in the Y direction, the rotary tool 6 is relatively moved along the X direction, which is the extending direction of the groove part 44A. Then, the metal material constituting the grooved metal member 46A flows to the opening surface 42 side of the groove part 44A while being continuously softened by the frictional heat, and the groove part 44A is closed by the softened material.As described above, in the closing step, the rotary tool 6 is moved (relatively moved) on a path parallel to an opening edge of the groove part 44A while being pressed against the opening surface 42 of the grooved metal member 46A. More specifically, the rotary axis A of the rotary tool 6 is moved on the path. The path described above is a path that is offset in the width direction of the groove part 44A with respect to the groove part 44A (more specifically, a center of the groove part 44A in the width direction), in other words, a linear path parallel to the opening edge of the groove part 44A along the Y direction. In the closing step, the rotary tool 6 is linearly moved along the X direction along the opening edge of the groove part 44A. As is apparent from the above description, a movement along the opening edge is a concept including a movement along a position offset from the opening edge. In the closing step, the groove part 44A is closed by the softened material of the opening surface 42.The flow of the softened metal material is a plastic flow while maintaining a solid phase, and a softened metal that has reached a region of the groove part 44A on the opening 42 side, which is a part positioned near the head 62, remains at its position (that is, does not flow downward toward the bottom side of the groove part 44A). Therefore, the groove part 44A can be suitably sealed with the softened material.The relative movement of the rotary tool 6 may be performed by moving the rotary tool 6 in a state where the grooved metal member 46A as a workpiece is held on a fixed table, or may be performed by moving the grooved metal member 46A held on a movable table in a state where the rotary tool 6 is held at a predetermined position. Alternatively, the turning tool 6 can be relatively moved by moving both the turning tool 6 and the grooved metal member 46A. An aspect to be used may be selected according to a specification of the stirring friction device to be used.Machining conditions in the closing step are not particularly limited, but are preferably set according to materials, sizes, or the like of the turning tool 6 and the grooved metal member 46A as the workpiece. A rotational speed of the rotary tool 6 can be, for example, 1000 U / min to 5000 U / min. A pressing pressure of the turning tool 6 against the grooved metal member 46A may be, for example, 10 MPa to 20 MPa. A relative movement speed of the rotary tool 6 can be, for example, 200 mm / min to 1000 mm / min.Referring to FIG. 5, the displacement (i.e., the above-described trajectory) of the turning tool 6 in the Y direction with respect to the groove part 44A is set such that a part of the turning tool 6 is positioned inside an opening edge of the recessed part 44 (in the embodiment, the groove part 44A). More specifically, the displacement of the rotary tool 6 in the Y direction with respect to the groove part 44A is preferably set to satisfy the following conditions. Here, among inner surfaces of the groove part 44A that are opposed to each other in the Y direction that is the width direction, the inner surface on the side where the turning tool 6 is offset is referred to as a reference inner surface 51 of the recessed part 44, and the other inner surface (the inner surface on the side opposite to the reference inner surface 51) is referred to as an opposite inner surface 52.In FIG. 5, a diameter of the shoulder 61 of the turning tool 6 (hereinafter referred to as "shoulder diameter") is indicated by "S", a diameter of the head 62 (hereinafter referred to as "head diameter") is indicated by "P", and a width of the groove part 44A in the Y direction, which is the width direction (hereinafter referred to as "groove width"), is indicated by "G". A distance length (hereinafter referred to as "offset width") in the Y direction along the opening surface 42 from the reference inner surface 51 of the recessed part 44 (groove part 44A) to the rotation axis A of the rotary tool 6 is defined as "F". A distance length (hereinafter referred to as "machining margin") in the Y direction along the opening surface 42 from the reference inner surface 51 of the groove part 44A to the highest point of the turning tool 6 is defined as "R".An offset of the rotary tool 6 is preferably set such that a ratio (hereinafter referred to as "offset ratio (F / P)") of the offset width F from the reference inner surface 51 of the groove part 44A to the rotation axis A of the rotary tool 6 to the head diameter P is 0 or more and 1 or less. By setting the displacement ratio (F / P) to 0 or more, an amount of the metal material that is softened by the frictional stirring treatment (FSP) and flows into the groove part 44A can be sufficiently secured. Further, when the displacement ratio (F / P) becomes excessively high, the metal material softened by the friction stir machining (FSP) cannot reach the groove part 44A, but by reducing the displacement ratio to 1 or less, it can be ensured that the softened metal material flows into the groove part 44A.The highest point of the turning tool 6 from the reference inner surface 51 of the groove part 46A is a position that is forward of the rotational axis A of the turning tool 6 by a radius (0.5P) of the head 62 in the Y direction. Therefore, when the displacement ratio (F / P) is "0", a ratio of the machining margin R to the head diameter P (hereinafter referred to as a machining margin ratio (R / P)) is "0.5", and when the displacement ratio (F / P) is "1", the machining margin ratio (R / P) is "1.5". That is, a condition that "the offset ratio (F / P) is 0 or more and 1 or less" is equivalent to a condition that "the machining margin ratio (R / P) is 0.5 or more and 1.5 or less".In the closing step, when a pressing position of the rotary tool 6 against the opening surface 42 of the grooved metal member 46A is set, a corresponding condition may be satisfied based on the ease of handling the offset width F and the machining margin R.In addition, the offset width F is preferably set in a range where the shoulder 61 of the turning tool 6 covers the opposing inner surface 52 of the groove part 44A. Here, a distance length in the Y direction along the opening surface 42 from the opposing inner surface 52 of the groove part 44A to the rotation axis A of the rotary tool 6 is equal to a sum of the offset width F and the recessed part width G. When the distance length from the opposing surface 52 to the rotational axis A is less than or equal to a radius (0.5S) of the shoulder 61, the shoulder 61 covers the opposing inner surface 52 of the groove part 44A. Therefore, quantitatively speaking, the offset width F is preferably set to be equal to or smaller than a difference between the radius (0.5S) of the shoulder 61 and the recessed part width G (F≤0.5S-G). In the embodiment, the recessed part width G is a groove width Ga that is a width in the Y direction orthogonal to a movement path of the groove part 44A, and the offset width F is preferably set to be equal to or smaller than a difference between the radius (0.5S) of the shoulder 61 and the groove width GA (F≤0.5S - Ga). Accordingly, the groove part 44A can be closed in one passage (that is, in a process on one side in the Y direction with respect to the groove part 44A), and the machining efficiency is high.It should be understood that the offset width F need not necessarily be adjusted such that the shoulder 61 covers the opposing inner surface 52. In such a case, the groove part 44A can be closed in two passages. That is, after the first processing on one side in the Y direction with respect to the groove part 44A, the second processing can be performed on the opposite side (the other side in the Y direction) of the groove part 44A, and the groove part 44A can be closed by the cooperation of both. In this case, the offset width F is preferably set in a range where the shoulder 61 of the turning tool 6 covers a center position of the groove part 44A in the width direction, in quantitative terms, preferably set to be equal to or less than a half of a difference between the shoulder diameter S and the recessed part width G (F≤0.5(S-G)). In the embodiment, the offset width F is preferably set to be equal to or less than one half of a difference between the shoulder diameter S and the groove width Ga (F≤0.5(S - Ga)).A length of the head 62 of the turning tool 6 (hereinafter referred to as "head length" and indicated by "Q" in FIG. 5 ) is preferably set to a length that can secure sufficient strength even during machining. The head length Q is typically set to be equal to or smaller than the head diameter P.In the embodiment, it is preferable to use the turning tool 6 having the head diameter P that is a length different from the recessed part width G with respect to the recessed part width G. In the example shown, the rotary tool 6 having the head diameter P longer than the recessed portion width G is used. However, the disclosure is not limited to such a configuration, and the rotary tool 6 having the head diameter P that is a length less than or equal to the width G of the recessed part may be used. For example, when the groove part 44A is closed in one passage as described above, the rotary tool 6 having the head diameter P which is a length the same as the width G of the recessed part may be used. When the groove part 44A is closed in two passages as described above, the rotary tool 6 having the head diameter P which is a length about half of the width G of the recessed part can be used.As shown in FIGS. 1 and 6 to 8, the hollow metal member 1 obtained through these steps includes the body part 2 in which the internal space 21 is formed and the closing part 3 formed in a part on the surface side of the body part 2 with respect to the internal space 21. The body part 2 is derived 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 step becomes the body part 2 of the hollow metal member 1 to be finally obtained. the internal space 21 is discharged from the groove part 44A of the grooved metal member 46A. That is, in the groove part 44A of the grooved metal member 46A subjected to the closing step, a part except a part melted and flowed by the metal material softened and flowed in the closing step becomes the internal space 21 of the hollow metal member 1 to be finally obtained.As described above, in the providing step, the grooved metal member 46A having the groove part 44A can be provided with various shapes by casting, cutting, or the like. Therefore, by forming the groove part 44A of the grooved metal member 46A into a desired shape, the hollow metal member 1 having the internal space 21 with a desired shape can be finally obtained. For example, the hollow metal member 1 having the inner space 21 extending in two directions, the X direction and the Z direction can be obtained from the grooved metal member 46A having the groove part 44A having a depth longer (for example, two, three,..., ten times as long or more) than the head length Q of the turning tool 6.The closure part 3 is arranged to be offset outward with respect to the interior space 21. That is, the closing part 3 is disposed so as to be offset to the side opposite to a center of the inner space 21 in the width direction (Y direction) with respect to the inner space 21. The closing part 3 is disposed to be offset outward in the width direction (Y direction) with respect to an inner wall surface of the internal space 21 (an inner surface corresponding to the reference inner surface 51 described above). The closing part 3 is formed to extend along the X direction, which is the extending direction of the internal space 21, at a position offset in the Y direction with respect to the internal space 21. As viewed from the Z direction, the locking part 3 is formed in an elongated oval shape corresponding to a movement path of the shoulder 61 of the turning tool 6. The closing part 3 is made of a metal material that has been softened once by frictional stirring in the closing step and then cured again.The closing part 3 according to the embodiment is made as a body of particles having crystal sizes smaller than those of a metal material constituting the body part 2. An average particle diameter of the metal material forming the body part 2 is on the order of millimeters to submillimeter, while an average particle diameter of the metal material forming the closing part 3 is on the order of micrometers to subnometer.The closing part 3 according to the embodiment has a dent part (recess part) 31 in the vicinity of an end part of the internal space 21 in the X direction. The dent part 31 has an inner surface shape corresponding to an outer shape of the head 62 of the turning tool 6. In the embodiment, the dent part 31 has a pillar-shaped inner surface shape. The dent part 31 is formed in a bottomed shape and does not communicate with the internal space 21. A depth of the dent part 31 is equal to the head length Q of the turning tool 6.The closing part 3 according to the embodiment has a small dent part (recess part) 32 linearly extending from the dent part 31 along the X direction. The small dent part 32 is formed along a movement path of the head 62 of the rotary tool 6 as viewed in the Z direction. The small dent part 32 is formed in a shape of a shallow groove that is slightly dent in a recessed shape from an upper surface of the closing part 3. A depth of the small dent part 32 is shallower than the depth of the dent part 31 (shorter than the head length Q of the turning tool 6). In the embodiment, the depth of the small dent part 32 is shallower than half the depth of the dent part 31, in the example shown, even shallower than 1 / 4 of the depth of the dent part 31.Second EmbodimentThe hollow metal member 1 and a manufacturing method thereof (a method for manufacturing a hollow metal member) according to a second embodiment will be described with reference to the drawings. In the embodiment, a specific configuration of the hollow metal member 1 is different from that of the first embodiment, and accordingly, a specific configuration of the indented metal member 46 as a raw material is different from that of the first embodiment. Hereinafter, regarding the hollow metal member 1 and the manufacturing method thereof according to the embodiment, differences from the first embodiment will be mainly described. Items not specifically stated are the same as those in the first embodiment and denoted by the same reference numerals, and detailed description thereof will be omitted.The hollow metal member 1 according to the embodiment is a part of a housing member 95 (see FIG. 9 ) that is used in, for example, a vehicle drive device and forms a rotating electric machine, a transmission mechanism, or the like therein. The housing member 95 is formed in a piece shape using a metal material, and a flow path 96 through which a fluid such as a lubricating oil or cooling water flows is formed therein. The hollow metal member 1 is used as a member underlying the housing member 95, and the flow path 96 is the internal space 21.In the embodiment, the hollow metal member 1 is also manufactured using friction stir machining (FSP). That is, in the method for manufacturing a hollow metal member according to the embodiment, the hollow metal member 1 is manufactured by a step of stirring a material softened by frictional heat by plastic flow using the rotating tool 6 rotating at a high speed. The method of manufacturing a hollow metal member includes a step of providing the recessed metal member 46 (providing step) and a step of closing the recessed part 44 formed in the recessed metal member 46 (closing step).In the providing step, the recessed metal member 46 in which the recessed part 44 is formed from the surface to the inside of the metal member 41 is provided. In the embodiment, as shown in FIG. 10, in the providing step, a hole-provided metal member 46B in which a hole part 44B having a predetermined diameter extending along a depth direction is formed from the surface to the inside of the metal member 41 is provided. The holed metal member 46B of the embodiment can be formed as a base body by performing drilling on the metal member 41.A shape of the hole part 44B of the holed metal member 46B is set 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 part 44B is set to have the shape of the desired internal space 21 (flow path 96) and is a shape extending in a direction for opening in the surface (opening surface 42) of the metal member 41. In the example shown in FIG. 10, the perforated metal member 46B includes a hole portion 44B in the form of a circular hole that extends in the Z direction until it reaches the opening surface 42 while having the same shape as the desired internal space 21 (flow path 96). In this example, the Z direction is the depth direction of the hole part 44B.In the closing step, the hole part 44B is closed by the friction stir machining (FSP) for the holed metal member 46B. The friction stir processing (FSP) is performed using a friction stir apparatus provided with the rotary tool 6 of the normal specification as in the first embodiment.In the closing step, the rotating tool 6 is pressed against a position adjacent to the hole part 44B of the opening surface 42 of the holed metal member 46B while being rotated at a high speed. In the embodiment, the rotary tool 6 is pressed against a position (offset position) of the opening surface 42 of the holed metal member 46B adjacent to the hole part 44B in a radial direction of the hole part 44B. Then, the metal material forming the perforated metal member 46B is locally heated and softened by the frictional heat, and the head 62 enters an interior of the perforated metal member 46B. At this time, the head 62 enters the inside of the perforated metal member 46B until the lower surface of the shoulder 61 comes into contact with the opening surface 42 of the perforated metal member 46B.Next, while maintaining this state, as shown in FIG. 11, the turning tool 6 is relatively moved along the position adjacent to the hole part 44B of the opening surface 42 of the holed metal member 46B. That is, in a state in which the head 62 enters the inside of the perforated metal member 46B until the lower surface of the shoulder 61 comes into contact with the opening surface 42, the turning tool 6 is relatively moved along the position adjacent to the hole part 44B of the opening surface 42 of the perforated metal member 46B while being turned at a high speed. In the embodiment, the rotary tool 6 is relatively moved along a path parallel to an opening edge of the hole part 44B at a position on the opening surface 42 of the holed metal member 46B on the outer side of the opening edge of the hole part 44B in the radial direction. Then, the metal material forming the holed metal member 46B flows to the opening surface 42 side of the hole part 44B while being sequentially softened by the frictional heat, and the hole part 44B is closed by the softened material.As described above, in the closing step, the rotary tool 6 is moved (relatively moved) along a circular path that is concentric with the opening edge and has a large diameter over an entire circumference of the hole part 44B while being pressed against the opening surface 42 of the holed metal member 46B. In the closing step, the rotary tool 6 is moved over the entire circumference of the hole part 44B in a circular shape along the opening edge. In the closing step, the hole part 44B is closed by the softened material of the opening surface 42.Referring to FIG. 12, the displacement of the rotary tool 6 in the radial direction with respect to the hole part 44B is preferably set to satisfy the following conditions. In the embodiment, an inner surface of the hole part 44B is the reference inner surface 51 of the recessed part 44.The displacement of the rotary tool 6 is preferably set such that the ratio (displacement ratio (F / P)) of the displacement width F from the reference inner surface 51 of the recessed part 44 (hole part 44B) to the rotation axis A of the rotary tool 6 to the head diameter P is 0 or more and 1 or less. The displacement of the rotary tool 6 is preferably set such that the ratio of the machining allowance R to the head diameter P (machining allowance ratio (R / P) is 0.5 or more and 1.5 or less.In the embodiment, it is sufficient that the hole part 44B can be closed as a whole when the rotary tool 6 rotates once along the circular path concentric with the hole part 44B. In this case, the offset width F is preferably set, quantitatively speaking, preferably set to be less than or equal to a half of the difference between the shoulder diameter S and the recessed part width G (F≤0.5(S-G)) within a range where the schooler 61 of the rotary tool 6 covers a center of the hole part 44B. In the embodiment, the recessed part width G is a diameter of the hole part 44B (hereinafter referred to as "hole diameter Gb"), and the offset width F is preferably set to be equal to or less than a half of a difference between the shoulder diameter S and the hole diameter GB (F≤0.5(S - Gb)).As shown in FIG. 13, the hollow metal member 1 obtained through these steps includes the body part 2 in which the internal space 21 (flow path 96) is formed, and the closing part 3 formed in the part on the surface side of the body part 2 with respect to the internal space 21 (flow path 96). The closing part 3 is disposed to be offset outward with respect to the internal space 21 (flow path 96). That is, the closing part 3 is disposed so as to be offset to the side opposite to the center of the internal space 21 (flow path 96) with respect to the internal space 21 (flow path 96). The closing part 3 is disposed to be offset outward in the radial direction with respect to the inner wall surface (the inner surface corresponding to the reference inner surface 51 described above) of the inner space 21 (flow path 96). The closing part 3 is formed to have a diameter larger than the internal space 21 (flow path 96), and is disposed concentrically with the internal space 21 (flow path 96). As described above, according to one aspect, in the embodiment, even when the closure part 3 as a whole is concentric, as long as the closure part 3 is displaced outward at each position in a circumferential direction, "the closure part 3 is disposed so as to be displaced outward with respect to the inner wall surface of the internal space 21".The closing part 3 is made of a metal material that is softened once by the frictional stirring in the closing step and then re-cured. The closing part 3 is made as a body of particles having crystal sizes smaller than those of the metal material constituting the body part 2.The closing part 3 according to the embodiment has the dent part 31 at a position in the circumferential direction. The dent part 31 has an inner surface shape corresponding to an outer shape of the head 62 of the turning tool 6. The dent part 31 is formed in a bottomed shape and does not communicate with the internal space 21 (flow path 96). The closing part 3 according to the embodiment includes the small dent part 32 that extends from the dent part 31 annularly along the circumferential direction of the internal space 21 (flow path 96). The small dent part 32 is formed along the movement path of the head 62 of the turning tool 6 as viewed from the Z direction. The small dent part 32 is formed in a shape of a shallow groove that is slightly dent in a recessed shape from an upper surface of the closing part 3. The depth of the small dent part 32 is smaller than the depth of the dent part 31.Third EmbodimentThe hollow metal member 1 and a method of manufacturing the same (a method of manufacturing a hollow metal member) according to a third embodiment will be described with reference to the drawings. In the embodiment, a specific configuration of the rotary tool 6 provided in the friction stirring device used in the closing step is different from that of the first embodiment, and accordingly, a specific configuration of the hollow metal member 1 to be finally obtained is also different from that of the first embodiment. Hereinafter, regarding the hollow metal member 1 and the manufacturing method thereof according to the embodiment, differences from the first embodiment will be mainly described. Items not specifically stated are the same as those in the first embodiment and denoted by the same reference numerals, and detailed description thereof will be omitted.The turning tool 6 used in the embodiment is similar to that of the first embodiment in that the turning tool 6 has the cylindrical shoulder 61 and the head 62 coaxially integrated with the shoulder 61, but a specific configuration of the head 62 is different from that of the first embodiment. As shown in FIGS. 14, 15 to 16, the head 62 according to the embodiment includes a spiral part 63 continuous from the shoulder 61 and a receiving part 64 provided at an end part of the spiral part 63. The receiving part 64 includes a narrowed part 64A, a receiving body part 64B, and a pointed part 64C.In FIGS. 14, 15 to 16, a maximum diameter of the scroll member 63 (hereinafter referred to as "scroll diameter") is indicated by "H", a difference in elevation of a turn of the scroll member 63 (hereinafter referred to as "scroll pitch") is indicated by "J", and a difference in a radius of a turn of the scroll member 63 (hereinafter referred to as "scroll width") is indicated by "K". A diameter of the narrowed part 64A (hereinafter referred to as "narrowed diameter") is indicated by "N", and a length of the narrowed part 64A (the length between a lower end part of the spiral part 63 and the accommodation body part 64B, hereinafter referred to as "narrowed length") is indicated by "M". A diameter of the accommodating body part 64B (hereinafter referred to as "accommodating diameter") is indicated by "T", and a length of the accommodating body part 64B (hereinafter referred to as "accommodating length") is indicated by "U". An angle formed by a horizontal plane and a virtual straight line connecting outermost points at respective positions of the scroll member 63 (hereinafter referred to as "scroll angle") is defined as "α", and an angle formed by an outer surface of the tip member 64C and the horizontal plane (hereinafter referred to as "end angle") is defined as "β".The scroll part 63 is a part serving as a unit part of the head 62 (that is, a part that stirs a material when the rotary tool 6 rotates at a high speed). In an axial direction of the shoulder 61, the spiral part 63 is formed to draw a spiral while a diameter gradually decreases as it goes away from the shoulder 61 (toward the end side of the head 62). The spiral part 63 is formed at a position slightly inward in the radial direction of an outer surface of the shoulder 61. The spiral diameter H is set to be smaller than the shoulder diameter S. A ratio (H / S) of the spiral diameter H to the shoulder diameter S is not particularly limited, and may be, for example, 0.7 or more and 0.95 or less, or 0.75 or more and 0.85 or less.The spiral part 63 is formed to draw a spiral having a substantially constant width. The spiral width K is set to a substantially constant value. A ratio (K / H) of the spiral width K to the spiral diameter H is not particularly limited, and may be, for example, 0.05 or more and 0.2 or less, or 0.1 or more and 0.15 or less.The spiral part 63 is formed so as to draw a spiral with a substantially constant pitch. The spiral pitch J is set to a substantially constant value. A ratio (J / K) of the spiral pitch J to the spiral width K is not particularly limited, and may be, for example, 0.2 or more and 0.8 or less, or 0.3 or more and 0.6 or less.The spiral angle α is not particularly limited, and may be, for example, 22.5° or more and 60° or less, or 30° or more and 45° or less.The receiving part 64 is provided at the end part of the scroll part 63 for receiving the material frictionally stirred and softened by the scroll part 63 from below. The receiving part 64 includes the narrowed part 64A, the receiving body part 64B, and the tip part 64C in this order from the shoulder 61 (the spiral part 63) to the end part.The narrowed part 64A is a part positioned at the center of the head 62 and formed to be thinner than other parts. The narrowed portion 64A is formed slightly thinner than the lower end portion of the scroll portion 63. The narrowed diameter N is not particularly limited, and may be, for example, 3 mm or more and 6 mm or less, or 4 mm or more and 5 mm or less. The narrowed length M is not particularly limited, and may be, for example, 0.5 mm or more and 2.5 mm or less, or 0.8 mm or more and 1.8 mm or less.A ratio (N / H) of the narrowed diameter N to the spiral diameter H is not particularly limited, and may be, for example, 0.1 or more and 0.3 or less, or 0.15 or more and 0.25 or less. A ratio (M / Q) of the narrowed length M to the head length Q is not particularly limited, and may be, for example, 0.05 or more and 0.2 or less, or 0.08 or more and 0.15 or less. A ratio (M / N) of the narrowed length M to the narrowed diameter N is not particularly limited, and may be, for example, 0.1 or more and 0.25 or less, or 0.15 or more and 0.2 or less.The accommodating body part 64B is a part serving as a unit part of the accommodating part 64 (that is, a part that accommodates the softened material from below). The accommodating body part 64B is formed in the shape of a flat column. A receiving diameter T is not particularly limited, and is preferably set to be equal to or smaller than (see FIG. 17 ) the recessed part width G of the recessed part 44 of the recessed metal member 46 (in the embodiment, the groove width Ga of the groove part 44A of the recessed metal member 46A). A ratio (U / Q) of the recording length U to the head length Q is not particularly limited, and may be, for example, 0.2 or more and 0.4 or less, or 0.25 or more and 0.3 or less. A ratio (U / T) of the accommodation length U to the accommodation diameter T is not particularly limited, and may be, for example, 0.1 or more and 0.5 or less, or 0.2 or more and 0.4 or less.The tip part 64C is a tip part on one end side of the receiving part 64. the tip part 64C is formed with a flat inverted cone shape so that its diameter gradually decreases toward the end side (away from the receiving body part 64B). The tip part 64C serves as a guide part that aligns a center when a center of the rotary tool 6 in the Y direction deviates from a center of the recessed part 44 (the groove part 44A of the embodiment). The end angle β is not particularly limited, and may be, for example, less than or equal to the spiral angle α. The end angle β may be, for example, 7.5° or more and 30° or less, or 10° or more and 20° or less.In the embodiment, in the closing step, as shown in FIGS. 17 and 18, the rotary tool 6 is relatively moved along a center line C of the opening of the recessed part 44 (groove part 44A) using the friction stirring device with the rotary tool 6 having a specific specification as described above. That is, the rotary tool 6 is relatively moved along the center line C of the opening of the recessed part 44 (groove part 44A) while being rotated at a high speed in a state where the receiving part 64 enters the recessed part 44 (groove part 44A) and the spiral part 63 is in contact with an upper surface of the recessed metal member 46 (grooved metal member 46A). Then, while the metal material constituting the grooved metal member 46A is sequentially softened by the frictional heat and flows to the opening surface 42 of the groove part 44A, the metal material is received by the receiving part 64 from below, and the groove part 44A is closed by the softened material.In the embodiment, as shown in FIGS. 19 and 20, an escape hole 48 is formed at a position adjacent to an end part in the X direction of the recessed part 44 (groove part 44A) in the recessed metal member 46 (grooved metal member 46A). In the illustrated example, the escape hole 48 is provided at a position further adjacent to the end part in the X direction of the recessed part 44 (the groove part 44A) in the X direction, but may deviate in the Y direction when there is a space in the Y direction. An inner diameter and a depth of the escape hole 48 are set so as not to interfere with the head 62 (specifically, the receiving part 64) of the rotary tool 6.In the embodiment, since the rotating tool 6 has the receiving part 64, when the rotating tool 6 is raised and pulled out from the recessed metal member 46 (recessed metal member 46A) in a final aspect of the closing step, a recessed hole corresponding to an outer shape of the receiving part 64 is inevitably formed. Even in such a case, by moving the rotary tool 6 to the position of the escape hole 48 and then pulling out the rotary tool 6 in the final aspect of the closing step, the internal space 21 of the finally obtained hollow metal member 1 can be prevented from being unintentionally communicated with the exterior due to the inevitably generated recessed hole.As shown in FIGS. 19 and 20, the hollow metal member 1 obtained in the embodiment includes the body part 2 in which the internal space 21 is formed and the closing part 3 formed in the part on the surface side of the body part 2 with respect to the internal space 21. The origin of the body part 2 and the origin of the interior space 21 are the same as those of the first embodiment. Similarly to the first embodiment, the closing part 3 is composed as a body of particles having crystal sizes smaller than those of the metal material constituting the body part 2.In the embodiment, the closure member 3 has a bottom surface 34 and a beveled surface 35. The bottom surface 34 is formed in a shape corresponding to the recessed part 44 (groove part 44A) of the recessed metal member 46 (grooved metal member 46A). The bottom surface 34 is provided at a position slightly lower than an upper surface of the hollow metal member 1. The tapered surface 35 is gradually inclined upward from the bottom surface 34. The tapered surfaces 35 inclined upward toward the outside are provided on both sides in the Y direction with the center line C of the internal space 21 interposed therebetween and on both sides in the X direction of the internal space 21. The chamfered surface 35 is formed around the bottom surface 34 so as to surround an entire periphery of the bottom surface 34.In the embodiment, as shown in FIG. 21, the locking part 3 has a tool path 37 on a back surface (that is, a surface facing the internal space 21). The tool path 37 is a path generated when the rotary tool 6 moves while rotating, more specifically, a path generated on a back surface of the bottom surface 34 when the receiving part 64 moves while rotating. In the embodiment, the tool path 37 is a path formed by connecting a plurality of arc-shaped curves at substantially equal intervals in the X direction. As described above, one of the features of the hollow metal member 1 according to the embodiment is that the tool path 37 generated by the rotation and movement of the rotary tool 6 can be verified when the closing part 3 is viewed from the inner space 21 side.Other Embodiments(1) In each of the above embodiments, a configuration in which the recessed part 44 (groove part 44A / hole part 44B) of the recessed metal member 46 is opened only on a single surface has been described as an example. However, the disclosure is not limited to such a configuration, and the recessed part 44 of the metal recessed member 46 may be opened to a plurality of surfaces. In this case, in the closing step, the friction stir processing (FSP) is performed for each of a plurality of opening surfaces 42 to close the recessed part 44 by cooperation of a plurality of closing parts 3.(2) In each of the above embodiments, a configuration in which the cooling member 90 and the housing member 95 using the hollow metal member 1 are independent members has been mainly adopted and described. However, the disclosure is not limited to such a configuration, and the cooling member 90 and the housing member 95 using the hollow metal member 1 may be integrated. Alternatively, one or both of the cooling member 90 and the housing member 95 may be integrated with another member.(3) In each of the above embodiments, a configuration in which the recessed portion 44 formed in the recessed metal member 46 is the groove portion 44A extending along the longitudinal direction or the hole portion 44B extending along the depth direction has been described as an example. However, the recessed portion 44 is not limited to such a configuration, and may be formed in a more complicated shape such as an L shape, a T shape, a crank shape, or a meander shape.(4) The configurations disclosed in connection with the above embodiments (including the above embodiments and other embodiments, the same applies to the following) may be applied in combination with configurations disclosed in other embodiments as long as no contradiction arises. Regarding other configurations, the embodiments disclosed in the present specification are shown in all respects and can be appropriately modified without departing from the spirit of the disclosure.Overview of EmbodimentsIn summary, a method for manufacturing a hollow metal member according to the disclosure preferably has the following configurations.A method of manufacturing a hollow metal member for manufacturing a hollow metal member (1) which is a metal member (41) having an inner space (21) using a turning tool (6), comprising the steps of:a step of providing a metal member (46) provided with a recess in which a recessed part (44) corresponding to a desired inner space shape is formed from a surface to an inside of the metal member (41); anda step of moving the rotary tool (6) along an opening of the recessed part (44) while pressing the rotary tool (6) against an opening surface (42) which is a surface of the recessed metal member (46) on which the recessed part (44) is formed, and closing the recessed part (44) with a softened material of the opening surface (42).According to this configuration, the turning tool (6) is moved along the opening of the recessed part (44) while the turning tool (6) is pressed against the opening surface (42) of the recessed metal member (46) in which the recessed part (44) having a shape corresponding to the desired inner space shape is formed from the surface to the inside of the metal member (41) regardless of the shape of the turning tool (6). Thus, the recessed part ( 44) can be closed by the softened material using friction stir machining (FSP). Therefore, the hollow metal member ( 1) can be formed while securing a degree of freedom of a shape of the internal space ( 21).According to an aspect, it is preferable that in the recessed part closing step (44), the rotary tool (6) is moved along an opening edge of the recessed part (44).According to this configuration, the opening of the recessed part ( 44) is easily closed by the material softened in the friction stir machining (FSP). Therefore, the hollow metal member ( 1) in which the degree of freedom of the shape of the internal space ( 21) is secured can be formed appropriately using the rotary tool ( 6) having the normal specification generally used for the friction stir machining (FSP).According to an aspect, it is preferable that in the recessed part closing step (44), the rotary tool is moved in a range in which a ratio of an offset width (F) along the opening surface (42) from a reference inner surface (51) of the recessed part (44) to a rotation axis (A) of the rotary tool (6) to a diameter (P) of a head (62) of the rotary tool (6) is 0 or more and 1 or less.By setting the ratio (hereinafter referred to as "displacement ratio") of the displacement width (F) from the reference inner surface (51) of the recessed part (44) to the rotation axis (A) of the rotary tool (6) to the head diameter (P) of the rotary tool (6) to 0 or more, an amount of the material softened by the friction stir machining (FSP) can be sufficiently ensured. By setting the displacement ratio to 1 or less, it can be ensured that the material softened by the friction stir machining (FSP) flows to the opening surface ( 42) of the recessed part ( 44). Therefore, according to this configuration, the opening surface ( 42) of the recessed part ( 44) can be suitably closed by the softened material using the friction stir machining (FSP).In one aspect, it is preferable that the recessed part (44) is a groove part (44A) extending along a longitudinal direction (X), and the offset width (F) is set in a range in which a shoulder (61) of the turning tool (6) covers an inner surface (52) of the groove part (44A) opposite to the reference inner surface (51).According to this configuration, the opening surface ( 42) of the groove part ( 44A) can be closed by a process performed along a position adjacent to the groove part ( 44A) formed in the recessed metal member ( 46). Therefore, the hollow metal member ( 1) can be formed efficiently.According to an aspect, it is preferable that the recessed part (44) is a groove part (44A) extending along a longitudinal direction (X), and in the recessed part closing step (44), the rotary tool (6) is linearly moved along at least one of opening edges of the groove part (44A) along the longitudinal direction (X).According to this configuration, when the recessed part ( 44) is the groove part ( 44A) extending along the longitudinal direction (X), the groove part ( 44A) can be properly closed in the step of closing the recessed part ( 44).According to an aspect, it is preferable that the recessed part (44) is a hole part (44B) extending along a depth direction (Z), and in the step of closing the recessed part (44), the rotary tool (6) is moved over an entire periphery of the hole part (44B) in a circular shape along an opening edge.According to this configuration, when the recessed part ( 44) is the hole part ( 44B) extending along the depth direction (Z), the hole part ( 44B) can be properly closed in the step of closing the recessed part ( 44).According to an aspect, it is preferable that in the recessed part closing step (44), the rotary tool (6) is moved along a center line (C) of the opening of the recessed part (44).According to this configuration, even if a sufficient thickness is not secured at a position adjacent to the recessed part (44) in the metal member (41), the opening of the recessed part (44) can be closed by the material softened in the friction stir machining (FSP) using the rotary tool (6) having a specific specification. Therefore, the hollow metal member ( 1) in which the internal space ( 21) having a degree of freedom in shape is formed in a balanced manner in a width direction (Y) can be formed appropriately.The present specification further discloses a product (a hollow metal member ( 1)) manufactured by the above-described method for manufacturing a hollow metal member. Such a hollow metal member (1) preferably has the following configuration.The hollow metal component (1) having an interior space (21) has:a body part (2) in which the internal space (21) is formed in a desired shape; anda closing part (3) formed along the inner space (21) in a part on a surface side of the body part (2) with respect to the inner space (21), the closing part (3) being mainly composed of particles having crystal sizes smaller than a constituent material of the body part (2), whereinthe closing part (3) is arranged to be offset outward with respect to an inner wall surface of the inner space (21).According to this configuration, the closing part ( 3) can be provided in a part of the body part ( 2) closer to the surface than the internal space ( 21) using the friction stir machining (FSP). Since the step of forming a space forming the base for the internal space (21) in the metal member and the step of forming the closing part (3) can be separated, the internal space (21) can be formed while the degree of freedom in shape is secured. In addition, by disposing the closing part (3) so as to be offset outward with respect to the inner wall surface of the internal space (21), when the closing part (3) is provided using the friction stir machining (FSP), a part on the surface side with respect to the internal space (21) can be suitably closed. Therefore, the hollow metal member (1) has the inner space (21) having the desired shape.A tool (turning tool (6)) having a specific specification used for manufacturing the above-described hollow metal member (1) is also disclosed in the present specification. Such a turning tool (6) preferably has the following configuration.A turning tool (6) for manufacturing a hollow metal member (1) which is a metal member (41) having an interior space (21), comprising:a cylindrical shoulder (61); anda head (62) coaxially integrated with said shoulder (61), whereinthe head (62) has a spiral part (63) having a diameter decreasing away from the shoulder (61) in an axial direction of the shoulder (61), and a receiving part (64) provided at an end part of the spiral part (63) for receiving a material stirred and softened by the spiral part (63) from below.According to this configuration, the material is frictionally stirred by the spiral part ( 63) of the head ( 62), and the softened material can be caused to flow in the vicinity of the opening of the recessed part ( 44). Since the head (62) has the receiving part (64) at the end part of the spiral part (63), the softened material is received by the receiving part (64) from below and does not flow into the recessed part (44). Therefore, the recessed part (44) can be closed while the turning tool (6) is moved along the center line (C) of the opening of the recessed part (44). Therefore, by using the turning tool ( 6) having this configuration, the hollow metal member ( 1) in which the internal space ( 21) having a degree of freedom in shape is formed in a balanced manner in the width direction (Y) can be suitably manufactured.The hollow metal member (1) formed using the turning tool (6) having the specific specification described above is a hollow metal member (1) having an internal space (21) and has:a body part (2) in which the internal space (21) is formed in a desired shape; anda closing part (3) formed along the inner space (21) in a part on a side of a surface of the body part (2) with respect to the inner space (21), the closing part (3) being mainly composed of particles having crystal sizes smaller than a constituent material of the body part (2), whereinthe closing part (3) has slanted surfaces (35) inclined upward toward an outside on both sides in a width direction (Y) above a center line (C) of the internal space (21).Another hollow metal member (1) formed using the turning tool (6) having the specific specification described above is a hollow metal member (1) having an interior space (21) that includes:a body part (2) in which the internal space (21) is formed in a desired shape; anda closing part (3) formed along the inner space (21) in a part on a side of a surface of the body part (2) with respect to the inner space (21), the closing part (3) being mainly composed of particles having crystal sizes smaller than a constituent material of the body part (2), whereinthe closing part (3) has a tool path (37) generated by the rotating tool (6) moving while rotating on a back surface facing the internal space.The method for manufacturing a hollow metal member, the hollow metal member, and the turning tool according to the disclosure may have at least one of the effects described above.It is expressly emphasized that all features disclosed in the description and / or the claims are to be regarded as separate and independent from each other for the purpose of original disclosure as well as for the purpose of restricting the claimed invention independently of the combinations of features in the embodiments and / or the claims. It is expressly stated that all range specifications or specifications of groups of units disclose every possible intermediate value or subgroup of units for the purpose of original disclosure as well as for the purpose of restricting the claimed invention, in particular also as a boundary of a range specification.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2014-223 680 A

[0003]

Claims

A method of manufacturing a hollow metal member for manufacturing a hollow metal member (1) that is a metal member (41) having an internal space (21) using a turning tool (6), comprising: a step of providing a recessed metal member (46) in which a recessed part (44) corresponding to a desired internal space shape is formed from a surface to an inside of the metal member; and a step of moving the turning tool along an opening of the recessed part while pressing the turning tool against an opening surface (42) that is a surface of the recessed metal member on which the recessed part is formed, and closing the recessed part with a softened material of the opening surface.The method for manufacturing a hollow metal member according to claim 1, wherein in the recessed part closing step, the turning tool is moved along an opening edge of the recessed part.The method for manufacturing a hollow metal member according to claim 2, wherein in the recessed part closing step, the turning tool is moved in a range in which a ratio of an offset width (F) along the opening area from a reference inner surface (51) of the recessed part to a rotation axis (A) of the turning tool to a diameter (P) of a head (62) of the turning tool is 0 or more and 1 or less.The method for manufacturing a hollow metal member according to claim 2 or 3, wherein the recessed part is a groove part (44A) extending along a longitudinal direction (X), and in the recessed part closing step, the rotary tool is linearly moved along at least one of opening edges of the groove part along the longitudinal direction.The method for manufacturing a hollow metal member according to claim 2 or 3, wherein the recessed part is a hole part (44B) extending along a depth direction (Z), and in the recessed part closing step, the rotary tool is moved over an entire circumference of the hole part in a circular shape along an opening edge.The method for manufacturing a hollow metal member according to claim 1, wherein in the recessed part closing step, the turning tool is moved along a center line (C) of the opening of the recessed part.A hollow metal member having an internal space, comprising: a body part (2) in which the internal space is formed in a desired shape; and a closing part (3) formed along the internal space in a part on a side of a surface of the body part with respect to the internal space, wherein the closing part is mainly composed of particles having crystal sizes smaller than a constituent material of the body part, wherein the closing part is disposed to be offset outward with respect to an inner wall surface of the internal space.A hollow metal member having an internal space, comprising: a body part in which the internal space is formed in a desired shape; and a closing part formed along the internal space in a part on a side of the surface of the body part with respect to the internal space, the closing part being mainly composed of particles having crystal sizes smaller than a constituent material of the body part, wherein the closing part has tapered surfaces (35) inclined upward to an outside on both sides in a width direction (Y) above a center line of the internal space.A hollow metal member having an internal space, comprising: a body part in which the internal space is formed in a desired shape; and a closing part formed along the internal space in a part on a side of a surface of the body part with respect to the internal space, the closing part being mainly composed of particles having crystal sizes smaller than a constituent material of the body part, wherein the closing part has a tool path (37) generated by the rotating tool moving while rotating on a back surface facing the internal space.A turning tool for manufacturing a hollow metal member, which is a metal member having an inner space, comprising: a cylindrical shoulder; and a head coaxially integrated with the shoulder, wherein the head includes a spiral part (63) having a diameter decreasing away from the shoulder in an axial direction of the shoulder, and a receiving part (64) provided at an end part of the spiral part from below for receiving a material stirred and softened by the spiral part.

Images