Friction build-up method and jig for friction build-up method

Abstract

This friction build-up method comprises: a first step for inserting an annular jig onto a rod-shaped metal material; a second step for pressing the metal material with the inserted annular jig against a build-up base material while rotating the metal material around the major axis thereof; and a third step for forming a build-up layer by placing a fore-end portion of the metal material on the build-up base material, the metal material being softened by the heat of friction between the metal material and the build-up base material. The annular jig has: an inner circumferential surface which can slide on the metal material along the major-axis direction of the metal material in at least the first step; and a bottom surface which faces the build-up base material in the second step. In the second step, the annular jig is located at the fore end of the metal material. In the third step, the bottom surface of the annular jig may rotate while being in contact with the top surface of the build-up layer.

Description

Friction surfacing method and jig for friction surfacing method

[0001] The present disclosure relates to a friction surfacing method and a tool for the friction surfacing method.

[0002] Metal additive manufacturing (MAM) is sometimes used as one method for manufacturing metal parts. Because MAM generally involves a melting process, the structure of the manufactured metal part includes a solidification structure that differs from that of the base material. Therefore, the metal part is prone to embrittlement due to the solidification structure. For this reason, MAM methods that do not involve the melting process, i.e., methods for performing metal deposition without melting the metal, have recently attracted attention. For example, Patent Document 1 below discloses a build-up method that utilizes friction. Specifically, the friction build-up method discloses a friction build-up method in which a substantially cylindrical build-up layer material is pressed against the surface of a base material while rotating, and the build-up layer material is softened by frictional heat to perform build-up processing on the base material.

[0003] JP 2010-227967 A

[0004] In the build-up method using friction as disclosed in Patent Document 1, burrs are inevitably formed at the tip of the build-up layer material. Although it is unclear whether the burrs are caused by the build-up method, the build-up layer surface tends to become rough (particularly, irregular burrs tend to form on the top surface of the build-up layer). Therefore, a metal additive manufacturing method that does not include a melting step and that can form a smooth build-up layer surface is desired.

[0005] An object of one aspect of the present disclosure is to provide a friction surfacing method that does not include a melting step and that is capable of forming a smooth surface of a buildup layer.

[0006] A friction build-up method according to one aspect of the present disclosure comprises a first step of inserting an annular jig into a rod-shaped metal material, a second step of pressing the metal material through which the annular jig is inserted against the material to be built up while rotating the metal material around the longitudinal axis of the metal material, and a third step of forming a build-up layer by building a tip portion of the metal material, which is softened by frictional heat generated between the metal material and the material to be built up, onto the material to be built up.

[0007] A jig for a friction build-up method according to another aspect of the present disclosure comprises a main body portion that is annular in plan view and can be inserted into a rod-shaped metal material that is the raw material for the build-up layer, the main body portion having an inner surface that can slide against the metal material along the longitudinal direction of the metal material when the metal material is inserted through the main body portion, and a bottom surface that is closest to the tip of the metal material in the longitudinal direction, and when the tip portion of the softened metal material is built up on the material to be built up, the softened tip portion has a weight that allows it to penetrate between the material to be built up and the bottom surface.

[0008] According to one aspect of the present disclosure, a friction surfacing method can be provided that does not include a melting step and that can form a smooth surface of a buildup layer.

[0009] FIG. 1 is a schematic diagram showing a metal material to which a friction buildup jig according to an embodiment is attached. FIG. 2 is a flowchart of a friction buildup method. FIG. 3 is a schematic diagram of a main portion for explaining the friction buildup method. FIG. 4(a) is a schematic perspective view of a jig according to a modified example, and FIG. 4(b) is a schematic cross-sectional view of the jig according to the modified example. FIG. 5(a) shows a photograph of the appearance of the buildup layer formed in Test Example 6, and FIG. 5(b) shows a photograph of the appearance of the buildup layer formed in Test Example 5. FIG. 6(a) shows a photograph of the appearance of the third buildup layer formed in Test Example 8, and FIG. 6(b) shows a photograph of the appearance of the third buildup layer formed in Test Example 7. FIG. 7(a) shows a photograph of a cross section of the third buildup layer formed in Test Example 8. FIG. 7(b) shows a photograph of a cross section of the third buildup layer formed in Test Example 7. FIG. 8(a) shows a photograph of the appearance of the buildup layer formed in Test Example 13, and FIG. 8(b) shows a photograph of the appearance of the buildup layer formed in Test Example 14. FIG. 9 is a graph showing the relationship between the moving speed of the metal material and the thickness of the buildup layer. FIG. 10 is a photograph showing the bottom surface of the jig for Test Examples 9, 2, and 10 after the buildup layer has been formed. FIG. 11 is a schematic diagram showing the location for evaluating the mechanical properties of the third buildup layer for Test Example 7. FIG. 12 is a graph showing the measurement results of the Vickers hardness distribution for Test Example 7. FIG. 13 is a graph showing the measurement results of the Vickers hardness distribution for Test Example 8. FIG. 14 is a schematic diagram of the position at which tensile test specimens were taken for evaluating the interfacial strength between the multilayer buildup layer and the buildup material.

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, identical elements or elements having the same functions will be designated by the same reference numerals, and redundant explanations will be omitted. In this specification, the term "same" and similar words are not limited to "completely identical." Furthermore, since the drawings are intended to conceptually explain the embodiments, the dimensions and ratios of the depicted components may differ from the actual dimensions.

[0011] (1) Overview of the Friction Building Method In the friction building method (metal additive manufacturing) according to this embodiment, a building method utilizing friction is carried out, similar to the friction building method described in Patent Document 1. However, the building layer formed by this friction building method and the building material on which the building layer is formed do not have to be joined to each other. In other words, in this friction building method, friction stir welding does not have to be performed.

[0012]

[0010] As a specific example, the friction surfacing method according to this embodiment includes a first step of inserting an annular jig into a rod-shaped metallic material, a second step of rotating the metallic material through the annular jig about the longitudinal axis of the metallic material while pressing it against the workpiece, and a third step of forming a buildup layer by depositing a tip portion of the metallic material, which is softened by frictional heat generated between the metallic material and the workpiece, on the workpiece. Here, in one example, the annular jig has an inner peripheral surface that can slide against the metallic material along the longitudinal axis of the metallic material at least in the first step, and a bottom surface that faces the workpiece in the second step, and in the second step, the annular jig is positioned at the tip of the metallic material, and in the third step, the bottom surface of the annular jig rotates while contacting the top surface of the buildup layer.

[0013] (2) Friction Surfacing Jig Hereinafter, an example of a friction surfacing jig used in carrying out the friction surfacing method according to this embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic diagram showing a metal material to which the friction surfacing jig according to this embodiment is attached. FIG. 1 also shows a rod-shaped metal material M through which the friction surfacing jig 1 is inserted. Hereinafter, the longitudinal direction of the metal material M will be referred to as a first direction X, and the direction perpendicular to the first direction X will be referred to as a second direction Y. Hereinafter, viewing from the first direction X will also be referred to as a planar view.

[0014] The metallic material M is the raw material for the buildup layer BL (see FIG. 3 , described later) formed by the friction surfacing method according to this embodiment. The tip portion M1 of the metallic material M is the portion that contacts the workpiece P (see FIG. 3 , described later). The metallic material M may be a rod-shaped member containing a single type of metal, or a rod-shaped member containing multiple types of metals. In the latter case, the metallic material M is, for example, an alloy rod-shaped member. The metallic material M may include, for example, iron, titanium, aluminum, copper, magnesium, chromium, zinc, nickel, molybdenum, cobalt, and other metals. Specific examples of the metallic material M include aluminum rod-shaped members, aluminum alloy rod-shaped members, copper rod-shaped members, copper alloy rod-shaped members, titanium rod-shaped members, titanium alloy rod-shaped members, magnesium alloy rod-shaped members, Invar rod-shaped members (iron-nickel alloy rod-shaped members), and steel rod-shaped members. The steel rod-shaped member is, for example, a rod-shaped member made of medium carbon steel. In this embodiment, the metallic material M has a cylindrical shape, but is not limited thereto. For example, the metal material M may have a polygonal prism shape or an elliptical cylinder shape. The build-up material P is a member on which a build-up layer BL formed from softened metal material M is provided. The build-up material P may be a plate member made of the same material as the metal material M, or may be a plate member made of a material different from the metal material M. The build-up material P may contain the above-mentioned metals contained in the metal material M.

[0015] The jig 1 is an annular member (annular jig) that shapes the metal material M and the buildup layer BL during friction building up, and is attached to the metal material M at least during friction building up. The jig 1 is attached without being fixed to the metal material M. Therefore, the jig 1 can move along the first direction X even during friction building up. The jig 1 may also contact or engage with the metal material M that expands during friction building up. In this case, the jig 1 rotates in conjunction with the metal material M that rotates during friction building up, with the rotation direction of the jig 1 being the same as the rotation direction of the metal material M. The jig 1 is made of a material that does not soften or melt during friction building up. For this reason, it is preferable that the thermal conductivity of the jig 1 be low. It is also preferable that the jig 1 be made of a material to which the softened metal material M does not bond. Furthermore, it is preferable that the melting point of the jig 1 be high. In one example, the jig 1 may be made of carbon steel, stainless steel (e.g., SUS304), titanium, tungsten, cobalt, iridium, molybdenum, ceramics, or the like. In other words, the jig 1 may be a carbon steel jig, a titanium jig, a titanium alloy jig, a tungsten jig, a tungsten alloy jig, a cobalt jig, a cobalt alloy jig, an iridium jig, an iridium alloy jig, a molybdenum jig, a molybdenum alloy jig, or a ceramic jig. In this embodiment, the jig 1 is a single member, but it may also be a composite member. In the latter case, each member may be made of a different material.

[0016] The jig 1 includes a main body 10 having a ring shape in a planar view that can be inserted into the metal material M. In the present embodiment, the main body 10 has a circular ring shape, but is not limited thereto. The main body 10 may have, for example, a polygonal ring shape or an elliptical ring shape. The dimensions of the main body 10 are appropriately adjusted according to the dimensions of the metal material M. In one example, when the diameter of the metal material M is 20 mm, the dimension of the main body 10 along the first direction X is 30 mm to 100 mm in terms of heat resistance, strength, weight, and the like. In this case, the buildup layer BL can be contained inside the jig 1 in a planar view, and the jig 1 can be stably positioned. In other words, the posture of the jig 1 during friction buildup is stabilized, and the buildup layer BL is less likely to be extruded from between the jig 1 and the workpiece P in a planar view. The dimension (thickness) of the main body 10 along the second direction Y is thicker than the region where the metal material M is heated and thinner than the length of the metal material M along the first direction X. The dimension of the main body 10 along the second direction Y is, for example, 10 mm or more and 100 mm or less. The weight of the jig 1 can be adjusted by adjusting the dimensions of the main body 10. While one jig 1 is used in this embodiment, this is not limited thereto; two or more overlapping jigs 1 may be used. That is, two or more jigs 1 may be inserted into the metal material M. When two or more jigs 1 are used, the materials, shapes, and sizes of these jigs 1 do not need to be identical. By adjusting the dimensions and weight of the main body 10, the shape, thickness, etc. of the buildup layer BL formed on the buildup material P can be controlled. The main body 10 has an inner circumferential surface 10a, an outer circumferential surface 10b, a bottom surface 10c, and a top surface 10d. Additionally, the main body 10 has an inner portion 10e including an inner circumferential surface 10a and an outer portion 10f including an outer circumferential surface 10b.

[0017] The inner circumferential surface 10a is a portion that can slide against the metal material M along the first direction X when the metal material M is inserted through the main body 10, and has a cylindrical shape. Therefore, the shape of the inner circumferential surface 10a is substantially identical to the side shape of the metal material M, and the diameter of the inner circumferential surface 10a is substantially identical to the diameter of the metal material M. The shape of the inner circumferential surface 10a can be deformed depending on the side shape of the metal material M. That is, the shape of the inner circumferential surface 10a is not limited to a cylindrical shape. In this embodiment, the outer circumferential surface 10b is a curved surface, but this is not limited thereto. The outer circumferential surface 10b may also be an aggregate of multiple polygonal surfaces. From the viewpoint of easily inserting the metal material M into the main body 10, the diameter of the inner circumferential surface 10a may be approximately 0.05 mm or 0.1 mm larger than the diameter of the metal material M.

[0018] The bottom surface 10c has an annular shape and is the portion closest to the tip portion M1 of the metal material M in the first direction X when the metal material M is inserted through the main body 10. The bottom surface 10c can also be said to be the surface facing the workpiece P when the metal material M is inserted through the main body 10 (see FIG. 3 described later). The bottom surface 10c functions as a cutting surface that cuts the tip portion M1 of the metal material M, the surface of the softened metal material M, the surface of the buildup layer BL, etc. during friction buildup. The top surface 10d is the portion closest to the base end of the metal material M in the first direction X when the metal material M is inserted through the main body 10. In this embodiment, both the bottom surface 10c and the top surface 10d are smooth surfaces, but this is not limited thereto. At least one of the bottom surface 10c and the top surface 10d may have intended irregularities, grooves, slopes, etc.

[0019] The inner portion 10e is a portion capable of storing frictional heat generated between the metal material M and the cladding material P, and the outer portion 10f is a portion surrounding the inner portion 10e. The inner portion 10e may be a portion closer to the inner circumferential surface 10a than the center line of the thickness of the main body portion 10, or may be a portion of the main body portion 10 that can overlap the cladding layer BL. The outer portion 10f may be a portion closer to the inner circumferential surface 10a than the center line of the thickness of the main body portion 10, or may be a portion of the main body portion 10 that does not overlap the cladding layer BL. During friction cladding, the temperature of the outer portion 10f is lower than the temperature of the inner portion 10e. The cladding layer BL can be cooled at or near the outer portion 10f, thereby forming an edge in the width direction of the cladding layer BL. Furthermore, during friction cladding, the heat transferred from the inner portion 10e to the outer portion 10f is released to the outside. In this embodiment, the inner portion 10e and the outer portion 10f are integrally formed of the same material, but this is not limiting. For example, the inner portion 10e and the outer portion 10f may be formed of different materials. From the viewpoint of heat storage performance, the thermal conductivity of the inner portion 10e may be lower than the thermal conductivity of the outer portion 10f.

[0020] In this embodiment, the jig 1 has a weight that allows the softened tip portion M1 to penetrate between the workpiece P and the bottom surface 10c when the tip portion M1 of the softened metal material M is deposited on the workpiece P. This allows the softened tip portion M1 to penetrate between the workpiece P and the bottom surface 10c during friction deposition, and the jig 1 to rise above the workpiece P to the top of the deposition layer BL. Therefore, the deposition layer BL formed from the softened tip portion M1 can be sandwiched between the jig 1 and the workpiece P.

[0021] (3) Details of the Friction Surfacing Method Next, details of the friction surfacing method according to this embodiment will be described with reference to Figures 2 and 3. Figure 2 is a flowchart of the friction surfacing method. Figure 3 is a schematic diagram of the main parts for explaining the friction surfacing method. In Figure 3, the second direction Y is also referred to as the surface direction or horizontal direction of the workpiece P.

[0022] First, as shown in FIG. 2 , the jig 1 is inserted into a rod-shaped metal material M (first step ST1). In the first step ST1, the jig 1 is attached to the metal material M so that the jig 1 can slide on the metal material M along the first direction X. That is, in the first step ST1, the jig 1 is movable even if it interferes with the metal material M. In the first step ST1, the jig 1 is inserted into the metal material M according to the thickness and / or width of the buildup layer BL to be formed in the third step ST3 described later. A lubricant may be used when inserting the jig 1 into the metal material M. In one example, a lubricant containing boron nitride may be applied to the inner circumferential surface 10 a of the jig 1, and then the metal material M may be inserted into the jig 1.

[0023] Next, the metal material M, through which the jig 1 is inserted, is pressed against the workpiece P while being rotated around the longitudinal axis of the metal material M (second step ST2). In the second step ST2, a load is applied to the metal material M in the first direction X toward the workpiece P, and the metal material M is rotated clockwise or counterclockwise. The metal material M may rotate continuously or intermittently. As a result, in the second step ST2, the metal material M rubs against the workpiece P. At least at the start of the second step ST2, the jig 1 is positioned at the tip of the metal material M. That is, at least at the start of the second step ST2, the bottom surface 10c of the jig 1 faces and contacts the workpiece P. In addition, in the second step ST2, the tip portion M1 of the metal material M is surrounded by the jig 1. The load applied to the metal material M and the rotation speed of the metal material M are each appropriately adjusted depending on the material of the metal material M (i.e., the required frictional heat).

[0024] Next, as shown in FIG. 3 , the tip portion M1 of the metallic material M, which is softened by frictional heat generated between the metallic material M and the workpiece P, is deposited on the workpiece P to form the buildup layer BL (third step ST3). In the third step ST3, the metallic material M moves along the second direction Y on the workpiece P. As a result, the metallic material M softened by the frictional heat solidifies on the workpiece P, forming the buildup layer BL having the desired shape. The final shape of the buildup layer BL as viewed from the first direction X can be determined by the trajectory of the relative movement of the metallic material M with respect to the workpiece P. Note that the jig 1 also moves along the second direction Y in conjunction with the movement of the metallic material M. From the viewpoint of the stability of the thickness of the buildup layer BL, the movement speed of the metallic material M and the jig 1 along the second direction Y is, for example, 400 mm / min or more. The movement speed may be 600 mm / min or more.

[0025] The thickness and width of the buildup layer BL are adjusted by at least one of the dimensions and material of the metallic material M, the pressing speed of the metallic material M, the dimensions and material of the jig 1, and the movement speed of the metallic material M and the jig 1. Assuming that the buildup efficiency is 100% (i.e., assuming that all of the metallic material M is consumed as the buildup layer BL) and that the shape of the buildup layer BL is a rectangular parallelepiped, the volume of the buildup layer BL corresponds to the consumption of the metallic material M. In this case, the thickness t of the buildup layer BL can be calculated using the following equations 1 and 2 (φ: diameter of the metallic material M (mm), h: pressing speed of the metallic material M (mm / min), w: width of the buildup layer (mm), v: movement speed of the metallic material M (mm / min)). From these equations 1 and 2, the thickness t of the buildup layer BL can be controlled by the pressing speed and movement speed of the metallic material M. The pressing speed of the metal material M can be adjusted, for example, by the dimensions and rotation speed of the metal material M, the load applied to the metal material M, the coefficient of friction between the metal material M and the cladding material P, etc.

[0026]

[0027]

[0028] In the third step ST3, a portion of the softened metallic material M penetrates between the jig 1 and the workpiece P. As a result, the jig 1 is lifted, and the bottom surface 10c of the jig 1 is positioned on the top surface of the buildup layer BL, with the buildup layer BL being sandwiched between the jig 1 and the workpiece P. Additionally, in the third step ST3, the jig 1 comes into contact with the metallic material M, which has expanded due to the frictional heat, from the bottom side of the jig 1. As a result, in the third step ST3, the rotation direction of the jig 1 becomes the same as the rotation direction of the metallic material M, and the jig 1 rotates in conjunction with the rotation of the metallic material M. At this time, the bottom surface 10c of the jig 1 rotates while contacting the top surface of the buildup layer BL. Due to the rotation of the jig 1, at least a portion of the tip portion M1 of the metallic material M and the top surface of the buildup layer BL are sheared and flattened. In addition, the softened metal material M is cooled by the outer portion 10f of the jig 1, thereby stabilizing the width position of the buildup layer BL perpendicular to the first direction X and the direction of movement of the metal material M. In this way, the friction buildup method for forming the buildup layer BL on the workpiece P is carried out.

[0029] In addition to the above-described friction buildup method, the metal material M through which the jig 1 is inserted may be rotated and pressed against the buildup layer BL (step 4). Subsequently, the buildup layer BL may be thickened by depositing the tip portion M1 of the metal material M, which is softened by frictional heat generated between the metal material M and the buildup layer BL, onto the buildup layer BL (step 5). In step 5, the jig 1 may rotate while in contact with the thickened buildup layer BL. Repeating steps 4 and 5 above allows the buildup layer BL to be further thickened, enabling three-dimensional molding of the buildup layer BL.

[0030] According to the friction surfacing method of this embodiment described above, the buildup layer BL can be formed without performing a melting step. Furthermore, by using the jig 1 in the friction surfacing method, the buildup layer BL is less likely to spread irregularly, and the surface of the buildup layer BL is less likely to become rough. Therefore, according to the friction surfacing method of this embodiment, irregular burrs are less likely to form on the top surface of the buildup layer BL, and the surface of the buildup layer BL can be formed smoothly without including a melting step.

[0031] Additionally, in the third step ST3, the bottom surface 10c of the jig 1 rotates while contacting the top surface of the buildup layer BL. This shears the top surface of the buildup layer BL and the softened metal material M that will later become the top surface. This prevents irregular burrs from forming on the top surface of the buildup layer BL, making the top surface smooth. Therefore, the friction buildup method according to this embodiment does not include a melting step, and can form a smooth surface for the buildup layer BL.

[0032] Furthermore, since the tip portion M1 of the metal material M is also sheared, burrs are less likely to form on the metal material M. This allows for efficient use of the metal material M and the buildup layer BL to be formed with a high yield. Furthermore, in the second step ST2 and the third step ST3, the tip portion M1 of the metal material M is surrounded by the jig 1. This makes it difficult for frictional heat generated between the tip portion M1 and the buildup material P to diffuse into the air. In other words, this frictional heat is more likely to accumulate. Therefore, the use of the jig 1 promotes softening of the tip portion M1, allowing the buildup layer BL to be formed efficiently. Note that, since the jig 1 is positioned on the top surface of the buildup layer BL, the buildup layer BL is sandwiched between the jig 1 and the buildup material P. This introduces strain into the buildup layer BL, making it possible to control the microstructure of the buildup layer BL.

[0033] In one example, in the third step ST3, the rotation direction of the jig 1 is the same as the rotation direction of the metal material M, and the jig 1 rotates in conjunction with the rotation of the metal material M. In this case, the jig 1 can be rotated without using a mechanism for rotating the jig 1, and irregular burrs are less likely to be formed on the top surface of the buildup layer BL.

[0034] In one example, in the third step ST3, the metal material M may move on the build-up material P along the second direction Y. At this time, the moving speed of the metal material M along the second direction Y may be 400 mm / min or more. In this case, the thickness of the build-up layer BL is stabilized.

[0035] In one example, the main body 10 of the jig 1 has an inner portion 10e that can store frictional heat generated between the metal material M and the buildup material P, and an outer portion 10f that surrounds the inner portion 10e. This makes it easier for frictional heat generated between the tip portion M1 and the buildup material P to be stored in the inner portion 10e, and the softened metal material M is well cooled in the outer portion 10f. Therefore, the jig 1 can promote the softening of the metal material M while well aligning the width position of the buildup layer BL.

[0036] FIG. 4A is a schematic perspective view of a jig according to a modified example, and FIG. 4B is a schematic cross-sectional view of the jig according to the modified example. The jig 1A shown in FIGS. 4A and 4B is a composite member including a first member 21, a second member 22, and a third member 23 that are combined with each other. Therefore, the jig 1A according to the modified example can also be referred to as an assembly of multiple jigs. In this modified example, from the perspective of the frictional heat storage performance of the jig 1A, the thermal conductivity of the first member 21 is lower than that of the second member 22. Therefore, the material of the first member 21 is different from the material of the second member 22. In this modified example, the first member 21 is made of a ceramic such as alumina. The second member 22 is made of a material with a higher thermal conductivity than the ceramic, such as carbon steel, stainless steel, titanium, tungsten, cobalt, iridium, or molybdenum. The material of the third member 23 may be the same as the material of the first member 21, may be the same as the material of the second member 22, or may be different from the materials of the first member 21 and the second member 22. Note that the third member 23 does not necessarily have to be included in the jig 1A.

[0037] The first member 21 is a member capable of storing frictional heat generated between the metal material M and the cladding material P and has a cylindrical shape that can be inserted into the metal material M. The first member 21 is a member that performs the same function as the inner portion 10e (see FIG. 1) of the above embodiment. The first member 21 has a main body portion 21a and a flange portion 21b. The main body portion 21a has a circular ring shape in a plan view, but is not limited thereto. In a plan view, the main body portion 21a may have, for example, a polygonal ring shape or an elliptical ring shape. The dimensions of the main body portion 21a are appropriately adjusted depending on the dimensions and material of the metal material M. The dimension H1 of the main body portion 21a along the first direction X is, for example, 10 mm or more and 80 mm or less. The thickness of the main body portion 21a along the second direction Y depends on the type of metal material M, for example, but is, for example, 3 mm or more and 20 mm or less. In one example, the thickness of the main body portion 21a is 5 mm, 7 mm, or 10 mm. The shape of the inner peripheral surface of the main body portion 21a is substantially the same as the side shape of the metal material M, and the diameter of the inner peripheral surface is substantially the same as the diameter of the metal material M. The inner diameter D1 of the main body portion 21a is constant. One end portion 21c of the main body portion 21a is the portion closest to the tip portion M1 of the metal material M in the first direction X when the metal material M is inserted through the first member 21. The end portion 21c also functions as a cutting portion that cuts the tip portion M1 of the metal material M, the surface of the softened metal material M, the surface of the buildup layer BL, etc. during friction buildup. The other end portion 21d of the main body portion 21a is the portion closest to the base end of the metal material M in the first direction X when the metal material M is inserted through the main body portion 10. In this embodiment, the annular end surface 21e included in the end portion 21c is a smooth surface, but is not limited to this. The end surface 21e may have intended irregularities, grooves, slopes, etc.

[0038] The flange portion 21b is provided to prevent the first member 21 from detaching from the jig 1A. It is an annular portion that protrudes outward in the second direction Y from the end 21d of the main body portion 21a. When the metal material M is inserted through the main body portion 21a, the flange portion 21b is located at the uppermost position of the first member 21 and is hooked onto the inner circumferential surface 22a of the second member 22. This prevents the first member 21 from freely falling from the jig 1A. The flange portion 21b has a circular ring shape in a plan view, but is not limited thereto. The outer diameter D2 of the flange portion 21b is larger than the outer diameter of the main body portion 21a, for example, greater than 13 mm and equal to or less than 60 mm. For example, the outer diameter D2 is 30 mm, 40 mm, 45 mm, or 50 mm. The outer diameter D2 is constant, but is not limited thereto. The dimension H2 of the flange portion 21b along the first direction X is, for example, greater than 1 mm and equal to or less than 20 mm. From the viewpoint of the strength of the flange portion 21b, the dimension H2 may be 3 mm or more, or 5 mm or more.

[0039] The second member 22 has a ring shape and is capable of holding the first member 21 and dissipating heat transferred from the first member 21 to the outside. The second member 22 functions similarly to the outer portion 10f (see FIG. 1) of the above embodiment. A portion of the second member 22 may be closer to the inner circumferential surface of the main body portion 21a of the first member 21 than the center line of the thickness of the jig 1A. During friction buildup, the temperature of the second member 22 is lower than the temperature of the first member 21. This allows for the formation of an edge in the width direction of the buildup layer BL, as in the above embodiment. The second member 22 has a circular ring shape in plan view, but is not limited thereto. In plan view, the second member 22 may have, for example, a polygonal ring shape or an elliptical ring shape. The dimensions of the second member 22 are appropriately adjusted depending on the dimensions of the first member 21. The dimension H3 of the second member 22 along the first direction X is, for example, the same as the dimension H1. The thickness of the second member 22 along the second direction Y is, for example, not less than 5 mm and not more than 30 mm.

[0040] The inner circumferential surface 22a of the second member 22 is shaped to conform to the outer circumferential surface of the first member 21. Therefore, when the first member 21 is accommodated in the second member 22, or when the metal material M is inserted into the jig 1A, the inner circumferential surface 22a of the second member 22 and the outer circumferential surface of the first member 21 can fit together. At this time, the flange portion 21b of the first member 21 is hooked onto the inner circumferential surface 22a. The inner diameter of a portion of the second member 22 is the same as or substantially the same as the outer diameter of the main body portion 21a of the first member 21. The inner diameter of another portion of the second member 22 is the same as or substantially the same as the outer diameter D2 of the flange portion 21b of the first member 21. When the first member 21 is accommodated in the second member 22, one end face 22b of the second member 22 in the first direction X is flush with the end face 21e of the first member 21. This reduces the occurrence of variations in the surface of the buildup layer BL. When the first member 21 is housed in the second member 22, the other end face 22c of the second member 22 in the first direction X may be flush with another end face 21f of the first member 21, or may be located closer to the end face 21e than the end face 21f in the first direction X. In the latter case, a step is formed between the end faces 22c and 21f. By having the third member 23 fill this step, the first member 21 is less likely to fall off the second member 22 during friction building up, etc.

[0041] The third member 23 is a ring-shaped member that can prevent the first member 21 from falling off the second member 22. When the metal material M is inserted through the jig 1A, the third member 23 is positioned on both the first member 21 and the second member 22. This allows the third member 23 to function as a lid for the first member 21. The third member 23 has a circular ring shape in a plan view, but is not limited thereto. In a plan view, the third member 23 may have, for example, a polygonal ring shape or an elliptical ring shape. The inner peripheral surface 23a of the third member 23 is flush with the inner peripheral surface of the main body 21a of the first member 21. The bottom surface 23b of the third member 23 is a smooth surface. In the jig 1A, the bottom surface 23b is in close contact with the entire end surface 21f of the first member 21 and at least a portion of the end surface 22c of the second member 22. As described above, when a step is formed by the end surfaces 21f and 22c, a protrusion that can fit into the step may be provided on a portion of the bottom surface 23b. In this case, the third member 23 is less likely to separate from the first member 21 even when a force is applied from the second direction Y. The dimensions of the third member 23 are appropriately adjusted depending on the dimensions of the first member 21 and the second member 22. The dimension H4 of the third member 23 along the first direction X is, for example, 3 mm or more and 20 mm or less. From the perspective of the third member 23's function as a lid, the dimension H4 may be 10 mm or more. This allows the weight of the third member 23 to effectively press down on the first member 21 in the jig 1A. The thickness of the third member 23 along the second direction Y corresponds to, for example, the sum of the thicknesses of the first member 21 and the second member 22.

[0042] Even when the jig 1A according to the modified example described above is used, it is possible to properly align the width of the buildup layer BL while promoting the softening of the metal material M, as with the jig 1 of the above embodiment. In addition, in this modified example, by utilizing the heat storage performance of the first member 21, it is possible to properly form a buildup layer by the friction buildup method, even when a metal material that is relatively difficult to soften (e.g., medium carbon steel) is used.

[0043] The friction surfacing method and jig for the friction surfacing method according to the present disclosure are as described in [1] to

[18] below, and have been described in detail based on the above-mentioned embodiments and modified examples. [1] A friction surfacing method comprising: a first step of inserting an annular jig into a rod-shaped metallic material; a second step of pressing the metallic material through which the annular jig is inserted against a workpiece while rotating the metallic material about the longitudinal axis of the metallic material; and a third step of forming a buildup layer by depositing a tip portion of the metallic material, which is softened by frictional heat generated between the metallic material and the workpiece, onto the workpiece. [2] The friction surfacing method according to [1], wherein the annular jig has an inner peripheral surface that is slidable against the metallic material along the longitudinal direction of the metallic material at least in the first step, and a bottom surface that faces the workpiece in the second step, wherein the annular jig is positioned at the leading end of the metallic material at least at the start of the second step, and wherein the bottom surface of the annular jig rotates while contacting the top surface of the buildup layer at the third step. [3] The friction surfacing method according to [2], wherein the rotation direction of the annular jig is the same as the rotation direction of the metallic material at the third step, and the annular jig rotates in conjunction with the rotation of the metallic material. [4] The friction surfacing method according to [2], wherein the rotation direction of the annular jig is opposite to the rotation direction of the metallic material at the third step. [5] The friction surfacing method according to any of [2] to [4], wherein the metallic material moves on the workpiece in a direction perpendicular to the longitudinal direction at the third step. [6] The friction surfacing method according to [5], wherein the moving speed of the metallic material along the direction is 400 mm / min or more. [7] The friction surfacing method according to any one of [1] to [6], wherein in the first step, a jig corresponding to the thickness and / or width of the buildup layer formed in the third step is inserted into the metallic material as the annular jig.[8] The friction surfacing method according to any of [2] to [4], further comprising: a fourth step of pressing the metallic material, through which the annular jig is inserted, against the buildup layer while rotating it about a longitudinal axis of the metallic material; and a fifth step of thickening the buildup layer by depositing, on the buildup layer, a tip portion of the metallic material that is softened by frictional heat generated between the metallic material and the buildup layer, wherein in the fifth step, the annular jig rotates while contacting a top surface of the thickened buildup layer. [9] The friction surfacing method according to any of [1] to [8], further comprising: a fourth step of pressing the metallic material, through which the annular jig is inserted, against the buildup layer while rotating it about a longitudinal axis of the metallic material; and a fifth step of thickening the buildup layer by depositing, on the buildup layer, a tip portion of the metallic material that is softened by frictional heat generated between the metallic material and the buildup layer,

[10] The friction surfacing method according to any one of [1] to [9], wherein the annular jig is a carbon steel jig, a stainless steel jig, a titanium jig, a titanium alloy jig, a tungsten jig, a tungsten alloy jig, a cobalt jig, a cobalt alloy jig, an iridium jig, an iridium alloy jig, a molybdenum jig, a molybdenum alloy jig, or a ceramic jig.

[11] A jig for a friction surfacing method comprising a main body portion that is annular in plan view and can be inserted into a rod-shaped metallic material that is a raw material for a buildup layer, the main body portion having an inner circumferential surface that can slide against the metallic material along a longitudinal direction of the metallic material when the metallic material passes through the main body portion, and a bottom surface that is closest to a tip of the metallic material in the longitudinal direction.

[12] The jig for a friction surfacing method according to

[11] , wherein when a tip portion of the softened metallic material is built up on a workpiece, the softened tip portion has a weight that allows the softened tip portion to penetrate between the workpiece and the bottom surface.

[13] The jig for the friction surfacing method according to

[12] , wherein the main body portion has an inner portion capable of storing frictional heat generated between the metallic material and the workpiece, and an outer portion surrounding the inner portion.

[14] The jig for the friction surfacing method according to any of

[11] to

[13] , wherein the main body portion has an annular shape.

[15] The jig for the friction surfacing method according to claim

[11] or

[12] , comprising a first member and a second member that are combined with each other, wherein the first member has the main body portion, the second member houses the first member, and the thermal conductivity of the first member is lower than the thermal conductivity of the second member.

[16] The jig for the friction surfacing method according to

[15] , wherein the first member further has a flange portion protruding from the main body portion, and when the metallic material is inserted through the main body portion, the flange portion is located at the uppermost position of the first member and is latched onto the inner circumferential surface of the second member.

[17] The jig for the friction surfacing method according to

[15] or

[16] , wherein the first member is capable of storing frictional heat generated between the metallic material and the material to be overlaid, and the second member is capable of radiating heat transferred from the first member to the outside.

[18] The jig for the friction surfacing method according to any of

[15] to

[17] , further comprising a third member combined with the first member and the second member, and when the metallic material is inserted through the main body portion, the third member is located above both the first member and the second member.

[0044] However, one aspect of the present disclosure is not limited to the above embodiment, the above modification, and the above [1] to

[18] . One aspect of the present disclosure can be further modified within the scope of its gist. For example, in the third step of the above embodiment, the rotation direction of the jig may be opposite to the rotation direction of the metal material. For example, the rotation direction of the jig can be set opposite to the rotation direction of the metal material by attaching a mechanism for rotating the jig to the jig. Furthermore, although the jig is not fixed in the above embodiment and modification, this is not limited thereto. For example, the jig may be restricted from moving upward in the longitudinal direction. In this case, the distance between the bottom surface of the jig and the base material (or the buildup layer) can be set to any value, allowing for more precise control of the thickness of the buildup layer, the metal structure, and the like. Methods for restricting the upward movement of the jig include attaching a mechanism or member that restricts the movement to the metal material or the jig, and modifying the shape of the metal material.

[0045] The present disclosure will be explained in more detail by the following examples, but the present disclosure is not limited to these examples.

[0046] (Test Example 1) A round bar (diameter: 20 mm) made of aluminum alloy (A6063-T5) was prepared as the metal material for the buildup layer. A flat plate (plate thickness: 10 mm, width: 100 mm, length: 300 mm) made of aluminum alloy (A6063-T5) was prepared as the buildup material on which the buildup layer was to be formed. Additionally, a ring-shaped member (inner diameter: 20 mm, outer diameter: 40 mm, thickness: 20 mm) made of stainless steel (SUS304) was prepared as a jig through which the metal material was inserted.

[0047] First, a metal material was inserted into the jig, and the tip of the metal material was abutted against the main surface of the workpiece. This placed the jig on the tip of the metal material and on the main surface of the workpiece. Next, the metal material was rotated at a rotational speed of 1500 rpm while abutting the workpiece with a load of 1000 kgf. This generated frictional heat between the metal material and the workpiece, softening the metal material. Then, the metal material with the jig inserted was moved over the main surface of the workpiece at a speed of 200 mm / min. This resulted in a buildup layer formed from the softened metal material on the workpiece. The appearance of the buildup layer was observed using a three-dimensional shape measuring machine (Keyence Corporation, "VR-3200"). The width, thickness, surface roughness, etc. of the buildup layer were evaluated. In order to soften the metal material, the time (holding time) from when the tip of the metal material came into contact with the main surface of the workpiece to when the metal material began to move was set to 2 seconds.

[0048] (Test Example 2) A buildup layer was formed in the same manner as in Test Example 1, except that the metal material through which the jig was inserted was moved on the main surface of the workpiece at a speed of 300 mm / min. The buildup layer was evaluated in the same manner as in Test Example 1. In addition, the appearance of the jig after the buildup layer was formed was also evaluated.

[0049] Test Example 3 A buildup layer was formed in the same manner as in Test Example 1, except that the metal material through which the jig was inserted was moved on the main surface of the workpiece at a speed of 400 mm / min. The buildup layer was also evaluated in the same manner as in Test Example 1.

[0050] Test Example 4 A buildup layer was formed in the same manner as in Test Example 1, except that the metal material through which the jig was inserted was moved on the main surface of the workpiece at a speed of 500 mm / min. The buildup layer was also evaluated in the same manner as in Test Example 1.

[0051] Test Example 5 A buildup layer was formed in the same manner as in Test Example 1, except that the metal material through which the jig was inserted was moved on the main surface of the workpiece at a speed of 600 mm / min. The buildup layer was also evaluated in the same manner as in Test Example 1.

[0052] Test Example 6 A buildup layer was formed in the same manner as in Test Example 1, except that the jig was not inserted into the metal material. The buildup layer was evaluated in the same manner as in Test Example 1.

[0053] (Test Example 7) First, a buildup layer was formed on the workpiece using the same method as in Test Example 3. Next, the metal material with the jig inserted therethrough was rotated at a rotational speed of 1500 rpm while being abutted against the buildup layer at a load of 1000 kgf. The metal material with the jig inserted therethrough was then moved over the buildup layer at a speed of 400 mm / min to thicken the buildup layer (hereinafter, the thickened buildup layer will be referred to as the "second buildup layer"). Next, the metal material with the jig inserted therethrough was rotated at a rotational speed of 1500 rpm while being abutted against the second buildup layer at a load of 1000 kgf. The metal material with the jig inserted therethrough was then moved over the second buildup layer at a speed of 400 mm / min to thicken the second buildup layer. This resulted in the formation of a thickened second buildup layer (hereinafter, the thickened second buildup layer will be referred to as the "third buildup layer"), in which the three buildup layers were integrated. The third buildup layer was evaluated in the same manner as in Test Example 1. Additionally, the cross section of the third buildup layer was also evaluated. The cross section of the third buildup layer was obtained according to the following procedure. First, a central portion of the third buildup layer was cut out along a direction perpendicular to the direction of movement of the metal material (i.e., the width direction of the third buildup layer) using an NC wire-cut electric discharge machine (manufactured by Sodick Co., Ltd., "AG360L"). This exposed the cross section of the central portion. Next, the surface of the cross section was wet-polished using emery paper (No. 800 to No. 4000). Next, the surface was mirror-polished using diamond paste (average particle size: 3 μm, 1 μm combined). This resulted in the cross section of the third buildup layer.

[0054] (Test Example 8) First, a buildup layer was formed on the workpiece by the same method as in Test Example 6. Next, a third buildup layer was formed by the same method as in Test Example 7, except that a metal material without a jig inserted therein was used. The third buildup layer was evaluated in the same manner as in Test Example 1. In addition, the cross section of the third buildup layer was also evaluated.

[0055] (Test Example 9) A buildup layer was formed in the same manner as in Test Example 2, except that the outer diameter of the jig through which the metal material was inserted was set to 30 mm. The buildup layer was evaluated in the same manner as in Test Example 2. In addition, the appearance of the jig after the buildup layer was formed was also evaluated.

[0056] (Test Example 10) A buildup layer was formed in the same manner as in Test Example 2, except that the outer diameter of the jig through which the metal material was inserted was set to 50 mm. The buildup layer was evaluated in the same manner as in Test Example 2. In addition, the appearance of the jig after the buildup layer was formed was also evaluated.

[0057] Test Example 11 Using the same method as in Test Example 7, a thick buildup layer (hereinafter referred to as a "multi-layer buildup layer") was formed by integrating five buildup layers.

[0058] Test Example 12 Using the same method as in Test Example 8, a thick buildup layer (hereinafter referred to as a "multi-layer buildup layer") was formed by integrating five buildup layers.

[0059] Test Example 13: A round bar (diameter: 20 mm) made of medium carbon steel (S45C) was prepared as the metal material for the buildup layer. A flat plate (thickness: 10 mm, width: 100 mm, length: 300 mm) made of medium carbon steel (S45C) was also prepared as the buildup material on which the buildup layer was to be formed. Additionally, a ring-shaped member (inner diameter: 20 mm, outer diameter: 40 mm, thickness: 20 mm) made of stainless steel (SUS304) was prepared as a jig through which the metal material was inserted.

[0060] First, the metal material was inserted into the jig, and the tip of the metal material was abutted against the main surface of the workpiece. This placed the jig on the tip of the metal material and on the main surface of the workpiece. Next, the metal material was rotated at a rotational speed of 1500 rpm while abutting the workpiece with a load of 3000 kgf. This generated frictional heat between the metal material and the workpiece, softening the metal material. Then, the metal material with the jig inserted was moved over the main surface of the workpiece at a speed of 200 mm / min. This resulted in the formation of a buildup layer on the workpiece, made of the softened metal material. The appearance of the formed buildup layer was observed using a three-dimensional shape measuring machine (Keyence Corporation, "VR-3200").

[0061] Test Example 14: A buildup layer was formed using the same method as Test Example 13, except that the first to third members shown in Figures 4(a) and 4(b) were used as jigs. The appearance of the formed buildup layer was observed using a three-dimensional shape measuring machine (Keyence Corporation, "VR-3200"). Here, the inner diameter of the first member made of alumina (92%) was 20 mm, the length of the first member was 20 mm, the outer diameter of the main body of the first member was 25 mm, the outer diameter of the flange portion of the first member was 45 mm, and the thickness of the flange portion was 5 mm. The outer diameter of the second member made of SUS304 was 60 mm, and the thickness of the second member was 20 mm. The inner diameter of the third member made of SUS304 was 20 mm, the outer diameter of the third member was 60 mm, and the thickness of the third member was 10 mm. In Test Example 14, the first member was fitted onto the inner circumferential surface of the second member and was covered with the third member.

[0062] <Observation results of the shape of the buildup layer> Fig. 5(a) shows a photograph of the appearance of the buildup layer formed in Test Example 6. Fig. 5(b) shows a photograph of the appearance of the buildup layer formed in Test Example 5. Fig. 6(a) shows a photograph of the appearance of the third buildup layer formed in Test Example 8. Fig. 6(b) shows a photograph of the appearance of the third buildup layer formed in Test Example 7. In Figs. 5(a) and 5(b), "S" indicates the location where the buildup layer is first formed, and "F" indicates the location where the buildup layer is last formed. In Figs. 5(a) and 5(b) and Figs. 6(a) and 6(b), "AS (Advancing side)" indicates the advancing side, and "RS (Retreating side)" indicates the retreating side. Note that "A," "B," and "C" shown in Fig. 5(b) each indicate the location where the buildup layer thickness was measured.

[0063] As shown in Figure 5(a), numerous irregularities were formed on the surface of the buildup layer formed in Test Example 6. As shown in Figure 6(a), numerous irregularities were also formed on the surface of the thickened third buildup layer formed in Test Example 8. On the other hand, as shown in Figures 5(b) and 6(b), the surfaces of the buildup layers formed in Test Examples 5 and 7 were observed to be significantly smoother than the buildup layers of Test Examples 6 and 8. Furthermore, the variation in the width (i.e., the dimension from AS to RS) of the buildup layers formed in Test Examples 5 and 7 was observed to be significantly lower than that of Test Examples 6 and 8, respectively. Therefore, the left-right symmetry of the buildup layers formed in Test Examples 5 and 7 was significantly higher than that of the buildup layers formed in Test Examples 6 and 8, respectively. From the above, it was observed that the shape of the buildup layer significantly differed depending on whether or not a jig was used.

[0064] 7(a) shows a cross-sectional photograph of the third buildup layer formed in Test Example 8. FIG. 7(b) shows a cross-sectional photograph of the third buildup layer formed in Test Example 7. As shown in FIG. 7(a), the presence of numerous voids (i.e., unbonded portions of the buildup layers) surrounded by dashed lines was confirmed within the third buildup layer formed in Test Example 8. On the other hand, as shown in FIG. 7(b), no voids were observed within the third buildup layer formed in Test Example 7. From this, it can be inferred that the strength of the thickened buildup layer can differ significantly depending on whether or not a jig is used.

[0065] FIG. 8(a) shows a photograph of the appearance of the buildup layer formed in Test Example 13. FIG. 8(b) shows a photograph of the appearance of the buildup layer formed in Test Example 14. As shown in FIG. 8(a), the surface of the buildup layer formed in Test Example 13 had irregularities. In addition, there were areas in parts of the buildup layer that were presumably crushed by the jig. On the other hand, as shown in FIG. 8(b), the surface of the buildup layer formed in Test Example 14 was observed to be smoother than the buildup layer of Test Example 13. Furthermore, it was observed that the variation in the width of the buildup layer formed in Test Example 14 (i.e., the dimension from AS to RS) was significantly lower than that of Test Example 13. Therefore, the left-right symmetry of the buildup layer formed in Test Example 14 was significantly higher than that of the buildup layer formed in Test Example 13. The above suggests that a composite jig may be useful for materials with high softening temperatures, such as medium carbon steel.

[0066] <Relationship between the moving speed of the metallic material and the thickness of the build-up layer> Figure 9 is a graph showing the relationship between the moving speed of the metallic material and the thickness of the build-up layer. In Figure 8, the vertical axis represents the thickness of the build-up layer, and the horizontal axis represents the moving speed of the metallic material. Plot 31 represents the thickness at point A shown in Figure 5(b) for Test Example 1. Plot 41 represents the thickness at point B shown in Figure 5(b) for Test Example 1. Plot 51 represents the thickness at point C shown in Figure 5(b) for Test Example 1. Plots 32, 42, and 52 represent the thicknesses at points A to C, respectively, for Test Example 2. Plots 33, 43, and 53 represent the thicknesses at points A to C, respectively, for Test Example 3. Plots 34, 44, and 54 represent the thicknesses at points A to C, respectively, for Test Example 4. Plots 35, 45, and 55 represent the thicknesses at points A to C, respectively, for Test Example 5.

[0067] As shown in Figure 9, the thicknesses of points A to C in Test Example 1 differ by approximately 1 mm or more. Here, the higher the moving speed of the metal material, the smaller the variation in the thickness of the buildup layer. In Test Examples 3 to 5, the variation in the thickness of the buildup layer was significantly smaller than in Test Examples 1 and 2. Therefore, it can be said that friction buildup was performed with an appropriate heat input at a moving speed of 400 mm / min or more. In particular, it can be said that there was almost no variation in the thickness of the buildup layer in Test Example 5. Therefore, it can be said that friction buildup was performed with a more appropriate heat input at a moving speed of 600 mm / min. The thickness of point B in Test Example 3 was approximately 2.8 mm, the thickness of point B in Test Example 4 was approximately 2.3 mm, and the thickness of point B in Test Example 5 was approximately 1.8 mm. The width of the buildup layer in Test Examples 3 to 5 was approximately 33 mm.

[0068] When the plunger speeds for Test Examples 3 to 5 were calculated using Equations 1 and 2, the plunger speed for Test Example 3 was 1.96 mm / s, the plunger speed for Test Example 4 was 2.01 mm / s, and the plunger speed for Test Example 5 was 1.89 mm / s. From the above, it can be said that the plunger speeds for Test Examples 3 to 5 were almost identical. From this, it can be inferred that when the buildup width is constant, for example, increasing the rotation speed or load of the metallic material tends to increase the optimal value of the moving speed. Furthermore, when the buildup width is constant, it can be inferred that the buildup thickness tends to decrease with increasing rotation speed of the metallic material, that the buildup thickness tends to increase as the diameter of the metallic material increases, that the buildup thickness tends to increase as the load applied to the metallic material increases (i.e., as the plunger speed increases), and that the buildup thickness tends to decrease with increasing moving speed of the metallic material. The tendency for the buildup thickness to decrease with increasing moving speed of the metallic material can also be inferred from the contents of Figure 9.

[0069] <Relationship between jig size and buildup layer thickness> Although not shown, the difference between the thickness at point A and the thickness at point C in Test Example 9 was larger than the difference in Test Example 2. In addition, the buildup layer thickness in Test Example 10 was thinner than the buildup layer thicknesses in Test Examples 2 and 9. Even when the holding time in Test Example 10 was increased four times (8 seconds), the buildup layer thickness in Test Example 10 was still thin. It is presumed that the result of Test Example 10 is due to the weight of the jig.

[0070] FIG. 10 is a photograph showing the bottom surfaces of the jigs of Test Examples 9, 2, and 10 after the formation of the buildup layer. As shown in FIG. 10, in Test Examples 2 and 10, the bottom surfaces were discolored white over an area of ​​approximately 33 mm in diameter. In contrast, in Test Example 9, the entire bottom surface was discolored white. The white-discolored portions of the bottom surface are presumed to be portions that had been in contact with the buildup layer. On the other hand, the undiscolored portions of the bottom surface are presumed to be portions that had not been in contact with the buildup layer. Therefore, in Test Examples 2 and 10, it is presumed that a portion of the jig functioned as a heat storage portion, while another portion of the jig functioned as a cooling portion for the buildup layer, and that this cooling portion performed the function of shaping the surface of the buildup layer (particularly the edges in the width direction). In contrast, in Test Example 9, it is presumed that no portion of the jig functioned as a cooling portion for the buildup layer. Therefore, in Test Example 9, it is presumed that the jig did not have sufficient heat conduction control, which resulted in unstable heat supply to the metal material and the aforementioned variation in buildup layer thickness.

[0071] <Mechanical Property Evaluation> FIG. 11 is a schematic diagram showing the locations where the mechanical properties of the third buildup layer in Test Example 7 were evaluated. Below, the cross sections of the third buildup layer obtained in Test Examples 7 and 8 were used to measure the Vickers hardness distribution at the joint surface between the third buildup layer and the workpiece and in its vicinity. As shown in FIG. 11 , the Vickers hardness distribution at the joint surface between the third buildup layer 100 and the workpiece 200 and in its vicinity was measured at positions α, β, and γ. The Vickers hardness at each location was measured using a microhardness tester (FM-300, manufactured by Future Tech Co., Ltd.) under the following conditions: test load: 100 gf, hold time: 15 seconds, and measurement interval: 0.5 mm. Note that position α corresponds to the center of the third buildup layer in the width direction. Position β is closer to AS than the center of the third buildup layer in the width direction. Position γ is closer to RS than the center of the third buildup layer in the width direction. The distance between the position α and the position β and the distance between the position α and the position γ are each 8 mm.

[0072] Fig. 12 is a graph showing the measurement results of the Vickers hardness distribution of Test Example 7. Fig. 13 is a graph showing the measurement results of the Vickers hardness distribution of Test Example 8. In each of Figs. 12 and 13, the horizontal axis represents the distance from the joint surface between the third buildup layer and the workpiece, the vertical axis represents Vickers hardness, plot 60A represents the average hardness of the aluminum alloy (A6061-T6), and plot 60B represents the average hardness of the aluminum alloy (A6063-T5). In Figs. 12 and 13, plots 61 and 71 represent the Vickers hardness distribution at position α, plots 62 and 72 represent the Vickers hardness distribution at position β, plots 63 and 73 represent the Vickers hardness distribution at position γ, and plots 64 and 74 represent the average hardness of each buildup layer. In each of Figures 12 and 13, region R1 corresponds to the buildup layer located at the top of the third buildup layer, region R2 corresponds to the buildup layer located in the center of the third buildup layer, region R3 corresponds to the buildup layer located at the bottom of the third buildup layer, and region R4 corresponds to the material to be built up.

[0073] 12 and 13, in Test Example 7, the Vickers hardness at positions α, β, and γ were approximately the same at a distance of 3 mm from the substrate surface. On the other hand, in Test Example 8, the Vickers hardness at positions α, β, and γ were significantly different at a distance of 3 mm from the substrate surface.

[0074] Fig. 14 is a schematic diagram of the positions at which tensile test specimens were taken for evaluating the interfacial strength between the multi-layer buildup layer and the buildup material. As shown in Fig. 14, in each of Test Examples 11 and 12, a plurality of tensile test specimens were taken at position α, a plurality of tensile test specimens at position β, and a plurality of tensile test specimens at position γ. These tensile test specimens were obtained by machining the specimens obtained in Test Examples 11 and 12 with a wire-cut electric discharge machine. Each of the obtained tensile test specimens was subjected to strain testing using a tensile testing machine (AGS-X 10kN) manufactured by Shimadzu Corporation at 27°C, a crosshead speed of 0.24 mm / min (initial strain rate: 1.0 x 10 －３ A tensile test was carried out under the condition of 1 / s.

[0075] In Test Example 11, it was confirmed that the tensile test specimen at position α, the tensile test specimen at position β, and the tensile test specimen at position γ all fractured with necking. Furthermore, in Test Example 11, the maximum fracture strengths of the tensile test specimen at position α, the tensile test specimen at position β, and the tensile test specimen at position γ were all approximately 150 MPa. In contrast, in Test Example 12, it was confirmed that only the tensile test specimen at position α fractured with necking. Additionally, in Test Example 12, the maximum fracture strength of the tensile test specimen at position α was approximately 140 MPa, the maximum fracture strength of the tensile test specimen at position β was approximately 110 MPa, and the maximum fracture strength of the tensile test specimen at position γ was approximately 90 MPa. These results confirmed that the use of a jig can stabilize and improve the interfacial strength between the buildup layer and the buildup material.

[0076] DESCRIPTION OF SYMBOLS 1... Jig, 10... Main body part, 10a... Inner peripheral surface, 10b... Outer circumferential surface, 10c... Bottom surface, 10d... Top surface, 10e... Inner part, 10f... Outer part, BL... Overlay layer, M... Metal material, M1... Tip part, P... Overlay material.

Claims

1. A friction surfacing method comprising: a first step of inserting an annular jig into a rod-shaped metal material; a second step of pressing the metal material through which the annular jig is inserted against a workpiece while rotating the metal material around its longitudinal axis; and a third step of forming a buildup layer by depositing a tip portion of the metal material, which is softened by frictional heat generated between the metal material and the workpiece, onto the workpiece.

2. A friction surfacing method as set forth in claim 1, wherein the annular jig has an inner peripheral surface that is slidable against the metal material along the longitudinal direction of the metal material in at least the first step, and a bottom surface that faces the workpiece in the second step, and at least at the start of the second step, the annular jig is positioned at the tip of the metal material, and in the third step, the bottom surface of the annular jig rotates while contacting the top surface of the buildup layer.

3. A friction surfacing method as described in claim 2, wherein in the third step, the rotation direction of the annular jig is the same as the rotation direction of the metal material, and the annular jig rotates in conjunction with the rotation of the metal material.

4. A friction surfacing method as set forth in claim 2, wherein in the third step, the rotation direction of the annular jig is opposite to the rotation direction of the metallic material.

5. A friction surfacing method according to any one of claims 2 to 4, wherein in the third step, the metal material moves on the workpiece in a direction perpendicular to the longitudinal direction.

6. A friction surfacing method according to claim 5, wherein the moving speed of the metal material along the direction is 400 mm / min or more.

7. A friction surfacing method as claimed in any one of claims 1 to 4, wherein in the first step, a jig corresponding to the thickness and / or width of the buildup layer formed in the third step is inserted into the metal material as the annular jig.

8. A friction surfacing method as claimed in any one of claims 2 to 4, further comprising: a fourth step of pressing the metallic material, through which the annular jig is inserted, against the buildup layer while rotating it around the longitudinal axis of the metallic material; and a fifth step of thickening the buildup layer by depositing on the buildup layer a tip portion of the metallic material that has been softened by frictional heat generated between the metallic material and the buildup layer, wherein in the fifth step, the annular jig rotates while contacting the top surface of the thickened buildup layer.

9. A friction surfacing method according to any one of claims 1 to 4, wherein the metal material is an aluminum rod-shaped member or an aluminum alloy rod-shaped member.

10. The friction surfacing method according to any one of claims 1 to 4, wherein the annular jig is a carbon steel jig, a stainless steel jig, a titanium jig, a titanium alloy jig, a tungsten jig, a tungsten alloy jig, a cobalt jig, a cobalt alloy jig, an iridium jig, an iridium alloy jig, a molybdenum jig, a molybdenum alloy jig, or a ceramic jig.

11. A jig for a friction build-up method, comprising a main body that is annular in plan view and can be inserted into a rod-shaped metal material that is the raw material for the build-up layer, wherein the main body has an inner circumferential surface that can slide against the metal material along the longitudinal direction of the metal material when the metal material is inserted through the main body, and a bottom surface that is closest to the tip of the metal material in the longitudinal direction.

12. A jig for a friction surfacing method as set forth in claim 11, wherein when the tip portion of the softened metal material is placed on the workpiece, the softened tip portion has a weight that allows it to penetrate between the workpiece and the bottom surface.

13. A jig for a friction surfacing method as described in claim 12, wherein the main body has an inner portion capable of storing frictional heat generated between the metal material and the material to be overlaid, and an outer portion surrounding the inner portion.

14. A jig for a friction surfacing method according to any one of claims 11 to 13, wherein the main body has a circular ring shape.

15. A jig for a friction surfacing method as set forth in claim 11 or 12, comprising a first member and a second member that are combined with each other, the first member having the main body portion, the second member housing the first member, and the thermal conductivity of the first member being lower than the thermal conductivity of the second member.

16. A jig for a friction surfacing method as described in claim 15, wherein the first member further has a flange portion protruding from the main body portion, and when the metal material is inserted through the main body portion, the flange portion is located at the uppermost position in the first member and is hooked onto the inner surface of the second member.

17. A jig for a friction surfacing method as described in claim 15, wherein the first member is capable of storing frictional heat generated between the metal material and the material to be overlaid, and the second member is capable of radiating heat transmitted from the first member to the outside.

18. A jig for a friction surfacing method as described in claim 15, further comprising a third member combined with the first member and the second member, wherein when the metal material is inserted through the main body, the third member is located on both the first member and the second member.

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