Tool body and method for manufacturing the tool body

Abstract

A tool body, which is a tool body for mounting a blade and is made of a sintered metal material. The sintered metal material has: a matrix phase made of metal, and a plurality of pores existing in the matrix phase.

Description

Technical Field

[0001] The present disclosure relates to a tool body and a method for manufacturing the tool body.

[0002] This application claims priority based on Japanese Patent Application No. 2020-025191 filed on February 18, 2020, and incorporates by reference all the descriptions recorded in the Japanese application. Background Art

[0003] Patent Document 1 discloses a machining tool for removal, which is composed of a cutting edge portion having a cutting edge and a main body for fixing the cutting edge portion. The tool body described in Patent Document 1 is made of a so-called porous metal. This porous metal is obtained by the following method: by gradually cooling and solidifying molten metal in which gas atoms are dissolved from a predetermined direction, gas atoms are precipitated during the solidification process, and a large number of voids are formed elongated along the cooling direction.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-66714 Summary of the Invention

[0007] The tool body of the present disclosure is a tool body for mounting an insert,

[0008] which is made of a sintered metal material,

[0009] The sintered metal material includes:

[0010] a matrix phase made of metal, and

[0011] a plurality of pores existing in the matrix phase.

[0012] The method for manufacturing the tool body of the present disclosure includes:

[0013] a step of compressing raw material powder to form a compacted body;

[0014] a step of machining the compacted body to form the shape of a tool body for mounting an insert; and

[0015] a step of sintering the compacted body machined into the shape of the tool body. Brief Description of the Drawings

[0016] Figure 1A Figure 1A FIG. is a side view showing an example of a cutter including the tool body according to the embodiment.

[0017] ​​​Figure 1B Figure 1B A plan view showing an example of a bite having a tool body according to an embodiment.

[0018] Figure 1C Figure 1C A side view showing an example of a bite having a tool body according to an embodiment.

[0019] Figure 2A Figure 2A A micrograph showing a cross-section of the sintered metal material of Specimen No. 1 fabricated in Test Example 1.

[0020] Figure 2B Figure 2B A micrograph showing a cross-section of the sintered metal material of Specimen No. 2 fabricated in Test Example 1.

[0021] Figure 2C Figure 2C A micrograph showing a cross-section of the sintered metal material of Specimen No. 3 fabricated in Test Example 1.

[0022] Figure 3 Figure 3 A graph showing the average cross-sectional area of pores in the sintered metal material of each specimen fabricated in Test Example 1.

[0023] Figure 4 Figure 4 A graph showing the average perimeter of pores in the sintered metal material of each specimen fabricated in Test Example 1.

[0024] Figure 5 Figure 5 A graph showing the average value of the maximum diameter of pores in the sintered metal material of each specimen fabricated in Test Example 1.

[0025] Figure 6 Figure 6 A graph showing the maximum value of the maximum diameter of pores in the sintered metal material of each specimen fabricated in Test Example 1.

[0026] Figure 7 Figure 7 A graph showing the minimum value of the maximum diameter of pores in the sintered metal material of each specimen fabricated in Test Example 1.

[0027] Figure 8A Figure 8A A micrograph showing a cross-section of the sintered metal material of Specimen No. 101 fabricated in Test Example 1.

[0028] Figure 8B Figure 8B ​​​​​​​​​​​​​​​​​​​​​​​Microscopic photograph showing a cross-section of the sintered metal material of Specimen No. 102 fabricated in Test Example 1.

[0029] Figure 8C Figure 8C Microscopic photograph showing a cross-section of the sintered metal material of Specimen No. 103 fabricated in Test Example 1. Detailed Description

[0030] [Problems to be Solved by the Present Disclosure]

[0031] Conventionally, a cutting tool with replaceable cutting edges has been known, which includes: a cutting insert having a cutting edge and a tool body for mounting the cutting insert. The cutting insert forms the cutting edge of the cutting tool. Generally, the tool body is fabricated by machining a molten material of a metal such as tool steel. Conventionally, the molten material constituting the tool body is a solid metal material and substantially has no pores.

[0032] The tool body described in Patent Document 1 is made of porous metal, and thus stable strength may not be obtained. According to Patent Document 1, by forming the tool body of porous metal, chattering and the like can be suppressed by the vibration damping effect generated by the voids. The above-mentioned porous metal is obtained by the following method: by cooling a molten metal from a predetermined direction, a large number of voids are formed elongated along a specific direction. Although these voids can be controlled to be substantially aligned in the longitudinal direction, it is difficult to control the size of each void and the position of the voids. Therefore, in the above-mentioned porous metal, there may be deviations in the size of the voids, and thus coarse voids may be generated. When coarse voids exist in the porous metal constituting the tool body, the strength of the tool body decreases. In addition, since the position of the voids cannot be controlled, in the tool body, coarse voids may be located at places where stress concentration occurs during use.

[0033] In addition, in the above-mentioned porous metal, a large number of voids are regularly formed along a specific direction. Therefore, it is considered that when the tool body is formed of such porous metal, the tool body is likely to break along a specific direction. In recent years, for the machining of complex shapes, sometimes a single tool is machined from multiple directions. When a large number of voids exist along a specific direction in the porous metal constituting the tool body, it is likely to break along a specific direction during machining, and thus the strength of the tool body may be insufficient.

[0034] One object of the present disclosure is to provide a tool body having excellent vibration damping properties and stable strength. Another object of the present disclosure is to provide a method for manufacturing a tool body having excellent vibration damping properties and capable of obtaining stable strength.

[0035] [Effects of the Present Disclosure]

[0036] ​​The vibration damping property of the tool body of the present disclosure is excellent and it has stable strength. The manufacturing method of the tool body of the present disclosure can manufacture a tool body with excellent vibration damping property and stable strength.

[0037] [Description of Embodiments of the Present Disclosure]

[0038] The present inventor proposed a solution in which the tool body is made of a sintered metal material. The sintered metal material is a material obtained by shaping and sintering metal powders.

[0039] First, the embodiments of the present disclosure are listed and described.

[0040] (1) The tool body related to the embodiment of the present disclosure is a tool body for mounting a blade,

[0041] which is made of a sintered metal material,

[0042] The sintered metal material includes:

[0043] a matrix phase made of a metal, and

[0044] a plurality of pores existing in the matrix phase.

[0045] Since the tool body of the present disclosure is made of a sintered metal material, it has excellent vibration damping property and stable strength at the same time. The sintered metal material can effectively suppress vibration because it has a plurality of pores in the matrix phase. Therefore, the vibration damping property of the sintered metal material is superior to that of a solid melted material. Thus, the vibration damping property of the tool body of the present disclosure is excellent. When the tool body of the present disclosure is used as a cutting tool, chattering during machining can be suppressed, thereby improving machining accuracy.

[0046] Generally, in a sintered metal material, a plurality of pores are isotropically dispersed in the matrix phase. "Isotropically dispersed" means that the size of the pores does not depend on the direction. That is, in a sintered metal material, pores are not formed elongated along a specific direction as in the porous metal described in Patent Document 1. Therefore, it is difficult for the sintered metal material to break along a specific direction. In addition, compared with the above-mentioned porous metal, the sintered metal material can suppress the formation of large pores. Therefore, by making the tool body of a sintered metal material, a reduction in the strength of the tool body can be suppressed. When the tool body of the present disclosure is used as a cutting tool, even if a single tool is machined from multiple directions, the deviation in the strength of the tool body in multiple directions is small. Therefore, the tool body of the present disclosure has stable strength.

[0047] In addition, since the sintered metal material has multiple pores, the weight of the tool body can be reduced compared to a solid fused material. Additionally, the sintered metal material can dissipate heat effectively through the multiple pores. Therefore, the tool body of the present disclosure also has excellent heat dissipation performance.

[0048] (2) As one embodiment of the tool body of the present disclosure, the following can be cited:

[0049] The relative density of the sintered metal material is 85% or more and 99.9% or less.

[0050] In the above embodiment, it is easy to balance the strength and vibration damping performance of the tool body. The above sintered metal material has a relative density of 85% or more and is dense. The above sintered metal material has fewer pores, so it is difficult for the pores to become the starting points of cracking. Thus, the above embodiment can improve the strength of the tool body. Since the relative density of the above sintered metal material is 99.9% or less, it contains pores. Thus, the above embodiment can improve the vibration damping performance and heat dissipation performance of the tool body. Additionally, the tool body can be made lighter.

[0051] (3) As one embodiment of the tool body of the present disclosure, the following can be cited:

[0052] The relative density of the sintered metal material is 93% or more and 99.5% or less.

[0053] The above embodiment can further balance the strength and vibration damping performance of the tool body. If the relative density of the sintered metal material is 93% or more, there are fewer pores, making it even more difficult for the pores to become the starting points of cracking. Thus, the above embodiment can further improve the strength of the tool body. Since the relative density of the sintered metal material is 99.5% or less, it moderately contains pores. Thus, the above embodiment can further improve the vibration damping performance and heat dissipation performance of the tool body. Additionally, the tool body can be made even lighter.

[0054] (4) As one embodiment of the tool body of the present disclosure, the following can be cited:

[0055] The average perimeter of the pores in any cross-section of the sintered metal material is 100 μm or less.

[0056] The above embodiment can further improve the strength of the tool body. Although the above sintered metal material contains multiple pores, each pore is difficult to become the starting point of cracking. The reason is that if the average perimeter of the pores is 100 μm or less, it can be considered that among the multiple pores, most pores have short perimeters. Pores with short perimeters have small cross-sectional areas and are thus difficult to become the starting points of cracking. Additionally, in the above embodiment, since the pores are small, the vibration damping performance of the tool body is improved.

[0057] Since the above-mentioned sintered metal material is manufactured by sintering at a relatively low temperature, its productivity is also excellent. Since the sintering temperature is low, thermal energy can be reduced. When sintering a compacted powder compact at a high temperature where a liquid phase is generated, the pores tend to become larger. Large pores are likely to be the starting points of cracking. Since the pores become the starting points of cracking, the strength of the sintered metal material is reduced. In contrast, if the compacted powder compact is sintered at a relatively low temperature, a sintered metal material with small pores can be obtained. In addition, compared with the case of high-temperature sintering, in the case of low-temperature sintering, it is easier to obtain a sintered metal material with excellent shape accuracy and dimensional accuracy. Therefore, the above-mentioned sintered metal material can improve the yield rate.

[0058] (5) As one mode of the tool body of the present disclosure, the following can be cited:

[0059] The average cross-sectional area of the pores in any cross-section of the sintered metal material is 500 μm 2 or less.

[0060] The above mode can further improve the strength of the tool body. Although the above-mentioned sintered metal material contains a plurality of pores, it is difficult for each pore to be the starting point of cracking. The reason is that if the average cross-sectional area of the pores is 500 μm 2 or less, it can be considered that most of the pores among the plurality of pores have a small cross-sectional area. Pores with a small cross-sectional area are difficult to be the starting points of cracking. In addition, in the above mode, since the pores are small, the vibration damping property of the tool body is improved.

[0061] Since the above-mentioned sintered metal material is manufactured by sintering at a relatively low temperature, its productivity is also excellent. The reason is as described above.

[0062] (6) As one mode of the tool body described in the above (4) or (5), the following can be cited:

[0063] The average value of the maximum diameter of the pores is 5 μm or more and 30 μm or less.

[0064] The above mode can further improve the strength of the tool body. In the above-mentioned sintered metal material, since the average value of the maximum diameter of the pores is within the above range, the circumference of the pores is short, or the cross-sectional area of the pores is small. If the average value of the maximum diameter of the pores is 30 μm or less, it can be considered that most of the pores among the plurality of pores are short and small. Therefore, it is difficult for each pore to be the starting point of cracking. In addition, since the pores are generally small in the above mode, the vibration damping property of the tool body is further improved. If the average value of the maximum diameter of the pores is 5 μm or more, the pores will not be too small, so the effect of suppressing vibration is improved.

[0065] (7) As one mode of the tool body of the present disclosure, the following can be cited:

[0066] The plurality of pores are isotropically dispersed in the matrix phase.

[0067] In the above manner, the pores are not oriented in a specific direction, so it is difficult to break along a specific direction.

[0068] (8) As one mode of the tool body of the present disclosure, examples include:

[0069] The metal is a ferrous alloy,

[0070] The ferrous alloy contains one or more elements selected from the group consisting of C, Ni, Mo, and B.

[0071] The above mode can improve the strength of the tool body. A ferrous alloy containing the above-listed elements, such as a steel of a ferrous alloy containing C, has excellent strength. Therefore, the tool body of the above mode has high strength.

[0072] (9) The manufacturing method of the tool body according to the embodiment of the present disclosure includes:

[0073] A step of compressing a raw material powder containing metal powder to form a compacted body;

[0074] A step of machining the compacted body to process it into the shape of a tool body to which a blade is to be mounted; and

[0075] A step of sintering the compacted body processed into the shape of the tool body.

[0076] The manufacturing method of the tool body of the present disclosure can manufacture a tool body made of a sintered metal material. As described above, by forming the tool body from a sintered metal material, a tool body with excellent vibration damping properties and stable strength can be obtained. In addition, when the tool body is made of a sintered metal material, lightweight and improved heat dissipation of the tool body can be achieved.

[0077] In the manufacturing method of the tool body of the present disclosure, the compacted body is machined to be processed into the shape of the tool body, so the tool body can be manufactured with good productivity. The compacted body before sintering is a compacted body directly formed from metal powder, so it is easier to perform cutting processing than the sintered metal material after sintering. In the manufacturing method of the present disclosure, since the compacted body is processed, the processing time is shortened, and the life of the processing tool is also extended compared with the case of processing the sintered metal material. In addition, since cutting processing is easy, it is easy to obtain a tool body with excellent shape accuracy and dimensional accuracy. Thus, the manufacturing method of the present disclosure can obtain a tool body with high shape accuracy and dimensional accuracy, thereby improving the yield.

[0078] (10) One aspect of the manufacturing method of the tool body of the present disclosure may include:

[0079] In the process of forming the compacted powder compact, the relative density of the compacted powder compact is 85% or more and 99.9% or less.

[0080] In the above aspect, by making the relative density of the compacted powder compact 85% or more, a sintered metal material with a relative density of 85% or more can be obtained. This sintered metal material has fewer pores, so it is difficult for pores to become the starting point of cracking. Thus, the above aspect can improve the strength of the tool body. In addition, in the above aspect, since the above-mentioned dense compacted powder compact is used, even when sintering is performed at a relatively low temperature of less than 1300 °C, a tool body composed of a dense sintered metal material with a high relative density can be obtained. On the other hand, by making the relative density of the compacted powder compact 99.9% or less, the relative density of the sintered metal material can be made 99.9% or less. This sintered metal material contains pores, so the vibration damping property and heat dissipation property of the tool body can be improved. In addition, the tool body can be lightened.

[0081] (11) One aspect of the manufacturing method of the tool body of the present disclosure may include:

[0082] In the process of sintering the compacted powder compact, the sintering temperature is 1000 °C or more and less than 1300 °C.

[0083] In the above aspect, the compacted powder compact is sintered at a temperature of 1000 °C or more and less than 1300 °C, so the productivity is excellent. By making the sintering temperature less than 1300 °C, the thermal energy can be reduced. In addition, since the sintering temperature is a relatively low temperature, the formation of large pores can be suppressed. Therefore, it is easy to obtain a sintered metal material with small pores. Typically, a sintered metal material with an average perimeter of pores of 100 μm or less, or an average cross-sectional area of pores of 500 μm 2 or less can be obtained. Thus, the above aspect can further improve the strength of the tool body. In addition, compared with the case of high-temperature sintering, in the case of low-temperature sintering, it is easy to obtain a tool body with excellent shape accuracy and dimensional accuracy. Therefore, the above aspect further improves the yield.

[0084] (12) One aspect of the manufacturing method of the tool body of the present disclosure may include:

[0085] The metal powder contains powder composed of an iron-based material with a Vickers hardness Hv of 80 or more and 200 or less.

[0086] The above method can obtain a tool body with high strength. Representative examples of iron-based materials include iron-based alloys. Iron-based alloys generally have high strength. Therefore, by forming the metal powder from an iron-based material, a sintered metal material with high strength can be obtained. In addition, by using a powder of an iron-based material having a Vickers hardness Hv of 80 or more and 200 or less as the metal powder, the above-mentioned dense compacted powder body can be easily obtained. By sintering the dense compacted powder body, a dense sintered metal material can be obtained. Thus, the above method can improve the strength of the tool body.

[0087] (13) As one mode of the manufacturing method of the tool body described in the above (12), the following can be cited:

[0088] The powder composed of the iron-based material contains powder composed of an iron-based alloy,

[0089] The iron-based alloy contains at least one element of Mo of 0.1 mass% or more and 2.0 mass% or less and Ni of 0.5 mass% or more and 5.0 mass% or less.

[0090] The above method can easily obtain a powder of an iron-based alloy having a Vickers hardness Hv of 80 or more and 200 or less.

[0091] [Details of the embodiments of the present disclosure]

[0092] Hereinafter, with reference to appropriate drawings, a tool body and a manufacturing method of the tool body according to the embodiments of the present disclosure will be described. The same reference numerals in the drawings denote the same objects. It should be noted that the present invention is not limited to these examples, but is represented by the claims, and is intended to include all variations within the meaning and scope equivalent to the claims.

[0093] [Tool body]

[0094] Mainly with reference to Figure 1A 、 Figure 1B 、 Figure 1C , the tool bodies 110 and 210 of the embodiments will be described. Hereinafter, Figure 1A 、 Figure 1B 、 Figure 1C will be collectively referred to as Figure 1.

[0095] The tools 100 and 200 shown in Figure 1 are cutting tools. Figure 1A The tool 100 shown is a cutting tool as an example of a fraise tool. Figure 1B 、 Figure 1CThe tool 200 shown is a turning tool as an example of a turning tool. The tool 100, 200 includes a blade 101, 201 and a tool body 110, 210 to which the blade 101, 201 is mounted. The blade 101, 201 is sometimes referred to as a chip. The tool body 110, 210 is a component to which the blade 101, 201 is fixed. Usually, the tool body 110, 210 is mounted on a tool post or a spindle.

[0096] The inserts 101 and 201 have cutting edges 102 and 202. The inserts 101 and 201 constitute the cutting edges of the tools 100 and 200. Examples of materials of the inserts 101 and 201 include cemented carbide, cermet, cubic boron nitride (CBN) sintered body, diamond sintered body, high-speed steel, etc. The shapes of the inserts 101 and 201 can be known shapes.

[0097] The tool body 110, 210 has a mounting seat 111, 211 for mounting the blade 101, 201. The mounting seat 111, 211 of this example is arranged at the front end of the tool body 110, 210. As an example of the mounting seat 111, 211, a recess corresponding to the shape of the blade 101, 201 can be cited. The shape of the mounting seat 111 of this example is approximately quadrilateral. The shape of the mounting seat 211 of this example is approximately triangular. The blade 101, 201 is mounted in such a manner that the cutting edge 102, 202 protrudes from the mounting seat 111, 211. In this example, the blade 101, 201 is detachably mounted on the mounting seat 111, 211 by a screw not shown in the figure. Specifically, as shown in FIG. Figure 1A , Figure 1B As shown, the blades 101, 201 can be screwed onto the mounting seats 111, 211 by inserting screws into the through holes 103, 203 formed in the blades 101, 201. The blades 101, 201 can be fixed to the mounting seats 111, 211 by brazing, for example. The shape of the tool body 110, 210 can adopt a known shape. The tool body 110 of the tool in this example is roughly cylindrical with an axial hole of a rotating axis. The outer diameter of the front end side of the tool body 110 is larger than the outer diameter of the root side. The number of mounting seats 111 of the tool body 110 and the number of blades 101 are 6. The tool body 210 of the turning tool in this example has: a square rod-shaped handle, and a block-shaped bracket integrally provided at the front end of the handle. A mounting seat 211 is provided on the bracket.

[0098] In this example, a cutting tool and a turning tool are exemplified as an example of a cutting tool, but the types of tools are not limited to cutting tools and turning tools. As cutting tools, for example, milling tools, turning tools, etc. can be cited. Representative examples include: drill bits, end mills, cutting tools, turning tools, etc. For example, when the tool is a drill bit or an end mill, the shape of the tool body can be, for example, cylindrical. For example, when the tool is a cutting tool, the shape of the tool body can be, for example, disc-shaped. In this case, a plurality of cutting blades are mounted on the outer periphery of the front end of the tool body. As the structure of the specific tool body, it can be cited that: there are a plurality of mounting seats on the outer periphery of the front end of the tool body, and the cutting blades are detachably mounted on each mounting seat. The shapes of the cutting blade and the tool body can be appropriately adopted as known shapes according to the type of the tool.

[0099] One of the features of the tool bodies 110 and 210 of the embodiment lies in the aspect of being made of a sintered metal material. The sintered metal material constituting the tool bodies 110 and 210 will be described. Figure 2A , Figure 2B , Figure 2C are microscope photographs respectively showing the cross-sections of the sintered metal material 1. Hereinafter, sometimes Figure 2A , Figure 2B , Figure 2C are collectively referred to as Figure 2.

[0100] [Sintered Metal Material]

[0101] The sintered metal material 1 shown in Figure 2 is a sintered material with a metal as the main body. As shown in Figure 2, the sintered metal material 1 includes: a matrix phase 10 made of a metal, and a plurality of pores 11 existing in the matrix phase 10. In Figure 2, the granular regions represented by dark colors, especially black, and the granular regions with white edges are the pores 11, and the rest is the matrix phase 10.

[0102] The sintered metal material 1 can effectively suppress vibration by having a plurality of pores 11 in the matrix phase 10. Therefore, the vibration damping property of the sintered metal material 1 is excellent. Thereby, the vibration damping property of the tool bodies 110 and 210 shown in Figure 1 is excellent. In addition, the sintered metal material 1 can effectively dissipate heat through the plurality of pores 11. Therefore, the heat dissipation property of the tool bodies 110 and 210 is excellent. Since the sintered metal material 1 has pores 11, it is lighter in weight than the melted material, and the weight reduction of the tool bodies 110 and 210 can be achieved.

[0103] As shown in FIG. 2, in the sintered metal material 1, a plurality of pores 11 are isotropically dispersed in the matrix phase 10. That is, in the sintered metal material 1, the pores 11 are not formed elongated along a specific direction. Therefore, the sintered metal material 1 is less likely to break along a specific direction. In addition, the pores 11 in any cross-section of the sintered metal material 1 shown in FIG. 2 are small. Since the tool bodies 110 and 210 shown in FIG. 1 are made of the sintered metal material 1, they have excellent strength in multiple directions. Thus, the tool bodies 110 and 210 have stable strength.

[0104] Hereinafter, a preferred embodiment of the sintered metal material 1 will be described mainly with reference to FIG. 2.

[0105] (Composition)

[0106] The metals constituting the matrix phase 10 may include various pure metals or alloys. Examples of pure metals may include: Fe (iron), Ti (titanium), Cu (copper), Al (aluminum), Mg (magnesium), etc. Examples of alloys may include: iron-based alloys, titanium-based alloys, copper-based alloys, aluminum-based alloys, magnesium-based alloys, etc. The strength of alloys is generally higher than that of pure metals. Therefore, the sintered metal material 1 having a matrix phase 10 made of an alloy has high strength. The higher the strength of the sintered metal material 1, the more the strength of the tool bodies 110 and 210 shown in FIG. 1 can be improved.

[0107] The iron-based alloy contains additive elements, and the balance is composed of Fe and impurities. The iron-based alloy contains the most Fe. Examples of additive elements may include one or more elements selected from the group consisting of C (carbon), Ni (nickel), Mo (molybdenum), and B (boron). Among iron-based alloys containing the above-listed elements in addition to Fe, such as steel, the tensile strength is high. The sintered metal material 1 having a matrix phase 10 made of such an iron-based alloy has excellent strength. Generally, the higher the content of each element, the higher the strength. On the other hand, the toughness tends to decrease. As long as the content of each element is not excessive, the decrease in toughness can be suppressed while increasing the strength.

[0108] The iron-based alloy containing C (typically carbon steel) has excellent strength. The content of C can be, for example, 0.1 mass% or more and 2.0 mass% or less. The content of C can be 0.1 mass% or more and 1.5 mass% or less, further 0.1 mass% or more and 1.0 mass% or less, 0.1 mass% or more and 0.8 mass% or less. It should be noted that the content of each element is the mass ratio when the iron-based alloy is set to 100 mass%.

[0109] In addition to contributing to the improvement of strength, Ni also contributes to the improvement of toughness. The content of Ni can be, for example, 0 mass% or more and 5.0 mass% or less. The content of Ni can be 0.1 mass% or more and 5.0 mass% or less, further can be 0.5 mass% or more and 5.0 mass% or less, and further can be 4.0 mass% or less, 3.0 mass% or less.

[0110] Mo and B contribute to the improvement of strength. In particular, Mo improves strength.

[0111] The content of Mo can be, for example, 0 mass% or more and 2.0 mass% or less, further can be 0.1 mass% or more and 2.0 mass% or less, and further can be 1.5 mass% or less.

[0112] The content of B can be, for example, 0 mass% or more and 0.1 mass% or less, further can be 0.001 mass% or more and 0.003 mass% or less.

[0113] As other additive elements, for example, Mn (manganese), Cr (chromium), Si (silicon), etc. can be cited. The content of each of these elements can be, for example, 0.1 mass% or more and 5.0 mass% or less.

[0114] The overall composition of the sintered metal material 1 can be analyzed, for example, by energy dispersive X-ray analysis (EDX or EDS), high-frequency inductively coupled plasma optical emission spectrometry (ICP-OES), etc.

[0115] Since the sintered metal material 1 constituting the tool bodies 110 and 210 shown in Fig. 1 has high strength, tool bodies 110 and 210 with high strength can be obtained. Thus, from the viewpoint of the strength of the tool bodies 110 and 210, the matrix phase 10 of the sintered metal material 1 is preferably composed of the above-mentioned iron-based alloy.

[0116] (Structure)

[0117] The sintered metal material 1 contains a plurality of pores 11 in any cross section. Each pore 11 is preferably small. If each pore 11 is small, it is difficult for each pore 11 to become a starting point of fracture. It is difficult for the sintered metal material 1 to fracture due to the pores 11, thereby further improving the strength of the tool bodies 110 and 210 shown in Fig. 1. In addition, since each pore 11 is small, the vibration damping property of the tool bodies 110 and 210 is improved. The details of the measurement methods of the perimeter of the pores, the cross-sectional area of the pores, the maximum diameter of the pores, and the relative density will be described in the test examples described later.

[0118] 《Perimeter of Pores》

[0119] The average perimeter of the pores 11 in any cross-section of the sintered metal material 1 is preferably 100 μm or less. The average perimeter of the pores 11 here means: obtaining an arbitrary cross-section from the sintered metal material 1, and in this cross-section, calculating the length of the contour of each of the multiple pores 11, and taking the average of the lengths of each contour.

[0120] If the average perimeter of the pores 11 is 100 μm or less, it can be considered that most of the pores 11 are pores 11 with short perimeters. The cross-sectional area of the pores 11 with short perimeters is small. It can be considered that the shorter the average perimeter of the pores 11, the smaller the cross-sectional area of each pore 11. If each pore 11 is small, it is difficult to become a starting point for cracking. Therefore, the sintered metal material 1 in which the average perimeter of the pores 11 satisfies 100 μm or less can further improve the strength of the tool bodies 110 and 210 shown in FIG. 1. Since the pores 11 of this sintered metal material 1 are small, the vibration damping property of the tool bodies 110 and 210 is improved. From the viewpoints of the strength and vibration damping property of the tool bodies 110 and 210, the above average perimeter is preferably 90 μm or less, more preferably 80 μm or less, and particularly preferably 70 μm or less.

[0121] The higher the relative density of the sintered metal material 1, the smaller the average perimeter of the pores 11 tends to be. For example, in the process of forming the compacted powder compact that is the raw material of the sintered metal material 1, if the relative density of the compacted powder compact is increased by increasing the forming pressure, the relative density of the sintered metal material 1 is increased. As a result, the pores 11 become smaller, and thus the above average perimeter easily becomes smaller. However, when the forming pressure is too high, it is difficult to take out the compacted powder compact from the mold, or the life of the mold is easily shortened. That is, when the forming pressure is too high, it may lead to a reduction in productivity. From the viewpoint of improving productivity, the above average perimeter can be, for example, 10 μm or more, and further can be 15 μm or more.

[0122] 《Cross-sectional Area of Pores》

[0123] The average cross-sectional area of the pores 11 in any cross-section of the sintered metal material 1 is preferably 500 μm 2 or less. The average cross-sectional area of the pores 11 here means: obtaining an arbitrary cross-section from the sintered metal material 1, and in this cross-section, calculating the cross-sectional area of each of the multiple pores 11, and taking the average of the cross-sectional areas of each.

[0124] If the average cross-sectional area of the pores 11 is 500 μm 2 or less, it can be considered that most of the pores 11 are pores 11 with small cross-sectional areas. It can be considered that the smaller the average cross-sectional area of the pores 11, the smaller the cross-sectional area of each pore 11. If each pore 11 is small, it is difficult to become a starting point for cracking. Therefore, the sintered metal material 1 in which the average cross-sectional area of the pores 11 satisfies 500 μm2 The following sintered metal material 1 can further improve the strength of the tool bodies 110 and 210 shown in Fig. 1. Since the pores 11 of the sintered metal material 1 are small, the vibration damping property of the tool bodies 110 and 210 is improved. From the viewpoints of the strength and vibration damping property of the tool bodies 110 and 210, the above average cross-sectional area is preferably 480 μm 2 Hereinafter, it is more preferably 450 μm 2 Hereinafter, it is particularly preferably 430 μm 2 Hereinafter.

[0125] The higher the relative density of the sintered metal material 1, the smaller the average cross-sectional area of the pores 11 tends to be. As described above, from the viewpoint of improving productivity without excessive forming pressure, the above average cross-sectional area can be, for example, 20 μm 2 Hereinafter, it can be further 30 μm 2 Hereinafter.

[0126] Preferably, the average perimeter of the pores 11 of the sintered metal material 1 is 100 μm or less, and the average cross-sectional area of the pores 11 is 500 μm 2 Hereinafter. In this case, it can be considered that most of the pores 11 are pores 11 with a small cross-sectional area and a short perimeter. Therefore, it is difficult for each pore 11 to become a starting point of fracture. As described above, from the viewpoints of the strength and vibration damping property of the tool bodies 110 and 210, the smaller the above average perimeter and the above average cross-sectional area, the more preferable.

[0127] 《Maximum diameter of pores》

[0128] In addition, the average value of the maximum diameters of the pores 11 is also preferably small. The average value of the maximum diameters of the pores 11 here means: an arbitrary cross-section is obtained from the sintered metal material 1, and in this cross-section, the maximum length of each of the plurality of pores 11 is obtained, and the average value of each maximum length is taken.

[0129] The average value of the maximum diameter of the pores 11 can be listed as, for example, 5 μm or more and 30 μm or less. If the above average value is 30 μm or less, it can be considered that most of the pores 11 are shorter and smaller. Such pores 11 are more difficult to become the starting point of cracking. Therefore, the sintered metal material 1 in which the average value of the maximum diameter of the pores 11 satisfies 30 μm or less can further improve the strength of the tool bodies 110 and 210 shown in FIG. 1. Since the pores 11 of the sintered metal material 1 are smaller as a whole, the vibration damping property of the tool bodies 110 and 210 is further improved. From the viewpoints of the strength and vibration damping property of the tool bodies 110 and 210, the above average value is preferably 28 μm or less, more preferably 25 μm or less, and particularly preferably 20 μm or less. If the above average value is 5 μm or more, the pores 11 will not be too small. Therefore, it is easy to obtain the vibration suppression effect brought by the pores 11. As described above, from the viewpoint of improving productivity without excessive forming pressure, the above average value can be 8 μm or more, and further can be 10 μm or more. From the viewpoint of achieving a good balance between strength and productivity, the above average value can be listed as, for example, 10 μm or more and 25 μm or less.

[0130] In addition, the maximum value of the maximum diameter of the pores 11 is also preferably small. This is because it is difficult for each pore 11 to become the starting point of cracking. The above maximum value is preferably 30 μm or less, more preferably 28 μm or less, and particularly preferably 25 μm or less.

[0131] The minimum value of the maximum diameter of the pores 11 can be listed as, for example, 3 μm or more and 20 μm or less, and further can be listed as 5 μm or more and 18 μm or less. If the above minimum value is within the above range, it is preferable in terms of improving productivity as described above.

[0132] 《Shape of Pores》

[0133] In the cross-section of the sintered metal material 1, the shape of the pores 11 can typically be listed as an irregular shape. As one of the reasons why the shape of the pores 11 is not a simple curved shape such as a circle or an ellipse but an irregular shape, it can be listed that the compacted powder compact is sintered at a relatively low temperature as described later.

[0134] (Relative Density)

[0135] The relative density of the sintered metal material 1 is preferably 85% or more and 99.9% or less. That is, the sintered metal material 1 contains pores 11 in the range of 0.1% or more and 15% or less. If the proportion of the pores 11 is within the above range, the pores 11 are less. Therefore, the sintered metal material 1 is dense. Since there are also few pores 11, it is difficult for the pores 11 to become the starting point of cracking. Thus, the sintered metal material 1 with a relative density of 85% or more can improve the strength of the tool bodies 110 and 210 shown in Fig. 1. If the relative density of the sintered metal material 1 is 99.9% or less, pores 11 are included, so the vibration damping property and heat dissipation property of the tool bodies 110 and 210 can be improved. In addition, the tool bodies 110 and 210 can be lightened. The relative density here means: for example, in any cross-section of the sintered metal material 1, the area ratio of the matrix phase 10 to the area of the cross-section (refer to Fig. 2).

[0136] From the viewpoint of the strength of the tool bodies 110 and 210, the relative density of the sintered metal material 1 is preferably 90% or more, more preferably 93% or more, 94% or more. In the case of achieving further high strength of the tool bodies 110 and 210, the above relative density is preferably 96% or more, particularly preferably 96.5% or more. The above relative density can be 97% or more, 98% or more. From the viewpoint of improving the vibration damping property and heat dissipation property of the tool bodies 110 and 210 and achieving the lightening of the tool bodies 110 and 210, the above relative density is preferably 99.5% or less, more preferably 99% or less.

[0137] If the relative density of the sintered metal material 1 is 99.9% or less, particularly 99.5% or less, excessive forming pressure can be prevented as described above, and thus productivity can be improved. From the viewpoint of improving productivity, the above relative density can be 99% or less.

[0138] From the viewpoints of the balance between the strength of the tool bodies 110 and 210 and vibration damping property, etc., and productivity, the relative density of the sintered metal material 1 can be, for example, 93% or more and 99.5% or less, and further can be 94% or more and 99% or less. If the above relative density is 93% or more, there are even fewer pores 11, so it is even more difficult for the pores 11 to become the starting point of cracking. Thus, the strength of the tool bodies 110 and 210 can be further improved. Since the above relative density is 99.5% or less and pores 11 are moderately included, the vibration damping property and heat dissipation property of the tool bodies 110 and 210 can be further improved. In addition, the tool bodies 110 and 210 can be further lightened.

[0139] (Use)

[0140] The tool bodies 110 and 210 of the embodiments can be used for cutting tools. Examples of cutting tools include milling tools, turning tools, etc. Representative examples can include: drill bits, end mills, cutting tools, lathe tools, etc.

[0141] (Main effects)

[0142] The tool bodies 110 and 210 of the embodiments are made of a sintered metal material 1. The sintered metal material 1 can effectively suppress vibration through a plurality of pores 11. Although the sintered metal material 1 contains a plurality of pores 11, the pores 11 are not oriented in a specific direction. Therefore, the tool bodies 110 and 210 of the embodiments have excellent vibration damping properties and stable strength. Since the tool bodies 110 and 210 have excellent vibration damping properties, when the tool bodies 110 and 210 are used as cutting tools, chatter and the like generated during machining can be suppressed. Thereby, the machining accuracy of the cutting tool is improved. In addition, the tool bodies 110 and 210 have stable strength, and the deviation of strength in multiple directions is small. Therefore, even when the tool bodies 110 and 210 are used as cutting tools and cutting operations are performed on one tool from multiple directions, breakage along a specific direction in the tool bodies 110 and 210 can be suppressed.

[0143] In addition, by forming the tool bodies 110 and 210 from the sintered metal material 1, the tool bodies 110 and 210 can be made lightweight. The sintered metal material 1 can effectively dissipate heat through a plurality of pores 11. Therefore, the tool bodies 110 and 210 also have excellent heat dissipation properties.

[0144] In addition, the above-mentioned sintered metal material 1 has a relative density of 85% or more, has fewer pores 11, and the pores 11 are small in any cross-section. Therefore, the pores 11 are less likely to become the starting point of breakage, and thus the sintered metal material 1 has excellent strength. Thereby, by forming the tool bodies 110 and 210 from the sintered metal material 1, the strength of the tool bodies 110 and 210 can be further improved. In addition, since the pores 11 of the sintered metal material 1 are small, the vibration damping properties of the tool bodies 110 and 210 are improved.

[0145] [Manufacturing method of tool body]

[0146] The tool bodies 110 and 210 of the embodiments can be manufactured, for example, by a manufacturing method of a tool body including the following processes.

[0147] First process: A process of compressing a raw material powder containing metal powder to form a powder compact.

[0148] Second process: A process of machining the powder compact into the shape of a tool body for mounting a cutting insert.

[0149] Third process: A process of sintering and processing a compacted powder compact into the shape of a tool body.

[0150] The method for manufacturing the tool body of the embodiment includes the above-described first to third processes. According to this manufacturing method, a tool body made of a sintered metal material can be manufactured. By forming the tool body from a sintered metal material, as described above, a tool body with excellent vibration damping properties and stable strength can be obtained. In addition, when the tool body is made of a sintered metal material, weight reduction and improvement of heat dissipation of the tool body can be achieved.

[0151] Hereinafter, each process will be described.

[0152] (First process: Forming process)

[0153] 〈Preparation of raw material powder〉

[0154] The raw material powder contains metal powder. The metal powder is preferably composed of a metal that is neither too soft nor too hard. By making the metal powder not too hard, plastic deformation is likely to occur due to compression. Therefore, it is easy to obtain a dense compacted powder compact with a relative density of 85% or more. By making the metal powder not too soft, it is easy to obtain a compacted powder compact with a relative density of 99.9% or less, that is, a compacted powder compact containing pores.

[0155] The raw material powder may contain metal powder with an appropriate composition according to the composition of the matrix phase of the sintered metal material. In addition, the hardness of the metal powder can be adjusted according to the composition of the metal powder. Examples of adjusting the hardness of the metal powder include: adjusting the composition of the metal powder, performing heat treatment on the metal powder, or adjusting the heat treatment conditions of the metal powder, etc. The composition of the metal powder can be referred to the item of (composition) of the above [sintered metal material].

[0156] For example, when the matrix phase of the sintered metal material is composed of an iron-based material, the raw material powder contains powder composed of an iron-based material. Hereinafter, the powder composed of an iron-based material is sometimes referred to as "iron-based powder". The iron-based material is pure iron or an iron-based alloy. If the iron-based material is an iron-based alloy in particular, a sintered metal material with high strength can be obtained as described above. The iron-based powder can be manufactured, for example, by water atomization method, gas atomization method, etc.

[0157] The Vickers hardness Hv of the iron-based powder is preferably 80 or more and 200 or less. By using an iron-based powder with a Vickers hardness Hv within the above range, it is easy to obtain the above-mentioned dense green compact. The iron-based powder with a Vickers hardness Hv of 80 or more is not too soft. If a raw material powder containing such an iron-based powder is used, a green compact containing pores can be obtained as described above. The iron-based powder with a Vickers hardness Hv of 200 or less is not too hard. If a raw material powder containing such an iron-based powder is used, a dense green compact can be obtained as described above. The above Vickers hardness Hv can be 90 or more and 190 or less, and further can be 100 or more and 180 or less, 110 or more and 150 or less.

[0158] In the case where the matrix phase of the sintered metal material is composed of an iron-based alloy, examples of the raw material powder are as follows.

[0159] (1) The raw material powder contains a first alloy powder. The first alloy powder is composed of an iron-based alloy having the same composition as the iron-based alloy constituting the above matrix phase.

[0160] (2) The raw material powder contains a second alloy powder and a first elemental powder. The second alloy powder is composed of an iron-based alloy containing a part of the additive elements contained in the iron-based alloy constituting the above matrix phase. The first elemental powder is a powder composed of each of the remaining additive elements among the above additive elements.

[0161] (3) The raw material powder contains the above second alloy powder and a third alloy powder. The third alloy powder is composed of an iron-based alloy containing the remaining additive elements among the above additive elements.

[0162] (4) The raw material powder contains pure iron powder and a second elemental powder. The second elemental powder is a powder composed of each of all the additive elements in the iron-based alloy constituting the above matrix layer.

[0163] A specific example of the raw material powder shown in the above (2) will be described. For example, in the case where the matrix phase of the sintered metal material contains C, Ni, and Mo as additive elements and the balance is composed of Fe and impurities in an iron-based alloy, the following second alloy powder and first elemental powder can be cited. The second alloy powder is a powder containing the above additive elements except C, that is, Ni and Mo, and the balance is composed of Fe and impurities. The first elemental powder is carbon powder. As an example of the above iron-based alloy, an element containing at least one of Mo of 0.1% by mass or more and 2.0% by mass or less and Ni of 0.5% by mass or more and 5.0% by mass or less can be cited. There are various compositions of the iron-based alloy containing Mo and Ni within the above range and having a Vickers hardness Hv of 80 or more and 200 or less. Therefore, it is easy to obtain a powder composed of the above iron-based alloy.

[0164] The size of the raw material powder can be appropriately selected. The average particle diameters of the above alloy powder and pure iron powder can be, for example, 20 μm or more and 200 μm or less, and further can be, for example, 50 μm or more and 150 μm or less. The average particle diameter of the third powder (except for carbon powder) can be, for example, about 1 μm or more and 200 μm or less. The average particle diameter of the carbon powder can be, for example, about 1 μm or more and 30 μm or less. The average particle diameter of the powder here is the particle diameter (D50) at which the cumulative volume in the volume particle size distribution measured by a laser diffraction type particle size distribution measuring device is 50%.

[0165] 〈Forming〉

[0166] The higher the relative density of the compacted powder compact, the denser sintered metal material with a higher relative density can be obtained. Therefore, a tool body composed of a dense sintered metal material with a high relative density can be finally obtained. The pores in the dense sintered metal material tend to become fewer and smaller. The relative density of the compacted powder compact can be, for example, 85% or more and 99.9% or less. By using a dense compacted powder compact with a relative density of 85% or more as the material, even if the sintering temperature is a relatively low temperature lower than the liquid phase temperature, a dense sintered metal material with a relative density of 85% or more and 99.9% or less can be obtained. In addition, the above compacted powder compact contains pores in the range of 0.1% or more and 15% or less. However, each pore becomes smaller due to compression. By sintering the above dense compacted powder compact at a relatively low temperature, a dense sintered metal material with few and small pores can be obtained. That is, a sintered metal material that substantially maintains the size and number of pores contained in the compacted powder compact can be obtained. Since the sintered metal material has few and small pores, the pores are difficult to become the starting point of cracking, and thus the strength is excellent. Thereby, the strength of the tool body can be improved.

[0167] The relative density of the compacted powder compact can be 90% or more, and further can be 93% or more, 94% or more, 96% or more, 96.5% or more, 97% or more, 98% or more. On the other hand, from the viewpoints of improving the vibration damping property and heat dissipation property of the tool body and realizing the light weight of the tool body, it is preferable that the sintered metal material moderately contains pores. The relative density of the compacted powder compact can be 99.5% or less, and further can be 99.4% or less, 99.2% or less, 99% or less. From the viewpoint of the balance between the strength of the tool body and the vibration damping property, etc., the relative density of the compacted powder compact can be, for example, 93% or more and 99.5% or less, and further can be 94% or more and 99% or less.

[0168] The forming of the compacted powder compact can typically be exemplified by using a die stamping device. The forming of the compacted powder compact can also be carried out, for example, by using a cold isostatic pressing (CIP) device. The shape of the die can be selected according to the shape of the compacted powder compact.

[0169] A lubricant can be coated on the inner peripheral surface of the die. By coating the lubricant, it is possible to suppress the sintering of the compacted powder compact to the die. Therefore, it is easy to obtain a compacted powder compact with excellent shape accuracy, dimensional accuracy, and density. Examples of the lubricant include higher fatty acids, metal soaps, fatty acid amides, higher fatty acid amides, etc.

[0170] The higher the forming pressure, the easier it is to obtain a dense compacted powder compact with a high relative density. The forming pressure can be, for example, 1560 MPa or more. The forming pressure can be 1660 MPa or more, 1760 MPa or more, 1860 MPa or more, 1960 MPa or more. If the forming pressure is reduced, it is easy to remove the compacted powder compact from the die, extend the life of the die, etc., thereby improving productivity.

[0171] The shape of the compacted powder compact can be a shape close to the shape of the tool body or a shape different from the shape of the tool body. Examples of the shape of the compacted powder compact include simple shapes such as cylindrical, cylindrical, and rectangular parallelepiped. If the shape of the compacted powder compact is a simple shape, it is easy to form a dense compacted powder compact with high precision even if the forming pressure is reduced to a certain extent. In addition, if it is a simple shape, the die cost can also be reduced.

[0172] (Second process: machining process)

[0173] The above-mentioned compacted powder compact is machined into the shape of the tool body. The machining performed on the compacted powder compact can typically be exemplified by cutting. As the cutting, for example, milling, turning, etc. can be cited. Since the compacted powder compact before sintering is a compacted powder compact obtained by directly forming metal powder, it is easier to perform cutting on it than the sintered metal material and the melted material after sintering. Thereby, the machining time is shortened, and the life of the machining tool is also extended compared to the case of machining the sintered metal material and the melted material. Therefore, by machining the compacted powder compact into the shape of the tool body, the tool body can be manufactured with good productivity. In addition, since it is easy to perform cutting, it is easy to obtain a tool body with excellent shape accuracy and dimensional accuracy. Thereby, a tool body with high shape accuracy and dimensional accuracy can be obtained, and the yield rate is improved.

[0174] The machining performed on the compacted powder compact is machining to form the shape of the tool body. By this machining, for example, a mounting seat for mounting a cutting blade at a predetermined position can be formed.

[0175] When the relative density of the compacted powder compact reaches a certain level, it is easy to perform cutting processing. In particular, for a compacted powder compact with a relative density of 85% or more, (for example) even if a large feed rate is set, cutting processing can be satisfactorily carried out. Therefore, it is easy to obtain a tool body with excellent shape accuracy and dimensional accuracy. In this regard, the yield rate is increased. In addition, if the feed rate is increased, the cutting time becomes shorter. Thus, performing cutting processing on the compacted powder compact contributes to improving the productivity of the tool body.

[0176] (Third process: sintering process)

[0177] The above-mentioned compacted powder compact processed into the shape of the tool body is sintered. The sintering temperature is preferably lower than the liquid phase temperature. Specifically, in the case where the metal powder is an iron-based powder, the sintering temperature can be, for example, 1000 °C or more and less than 1300 °C. The sintering temperature being lower than the liquid phase temperature is a relatively low temperature. Therefore, compared with the case of sintering at a high temperature where a liquid phase is generated, the thermal energy can be reduced. In addition, if the sintering temperature is a relatively low temperature, the formation of large pores can be suppressed. Therefore, it is easy to obtain a sintered metal material with small pores. Typically, a sintered metal material can be obtained in which the average perimeter of the pores is 100 μm or less, or the average cross-sectional area of the pores is 500 μm 2 The following sintered metal material. For example, by sintering a dense compacted powder compact with a relative density of 85% or more at a relatively low temperature, a dense sintered metal material with few and small pores can be obtained. In addition, compared with high-temperature sintering, low-temperature sintering is less likely to cause a reduction in shape accuracy and dimensional accuracy due to thermal shrinkage. Therefore, it is easy to obtain a tool body with excellent shape accuracy and dimensional accuracy, thereby increasing the yield rate. Thus, sintering the compacted powder compact at a relatively low temperature contributes to improving the productivity of the tool body.

[0178] The sintering temperature and sintering time can be adjusted according to the composition of the raw material powder, etc. In the case of using an iron-based powder, the sintering temperature is 1000 °C or more and less than 1300 °C.

[0179] The lower the sintering temperature, the easier it is for the amount of thermal shrinkage to become smaller. Therefore, it is easy to obtain a tool body with excellent shape accuracy and dimensional accuracy. From the viewpoints of reducing thermal energy and improving shape accuracy and dimensional accuracy, the sintering temperature is preferably 1250 °C or less, more preferably less than 1200 °C.

[0180] The higher the sintering temperature within the above range, the easier it is to shorten the sintering time. In this regard, the productivity is increased. From the viewpoint of shortening the sintering time, the sintering temperature can be 1050 °C or more, further can be 1100 °C or more.

[0181] From the viewpoint of reducing heat energy, achieving a good balance between accuracy and shortening the sintering time, the sintering temperature can be, for example, 1100 °C or higher and less than 1200 °C.

[0182] The sintering time can be, for example, 10 minutes or longer and 150 minutes or shorter.

[0183] The atmosphere during sintering can be, for example, a nitrogen atmosphere or a vacuum atmosphere. The vacuum atmosphere can be, for example, 10 Pa or less. If it is a nitrogen atmosphere or a vacuum atmosphere, the oxygen concentration in the atmosphere is low, and it is easy to suppress the oxidation of the sintered metal material.

[0184] (Other processes)

[0185] The manufacturing method of the above tool body can include: after the third process, a process of heat-treating the sintered metal material obtained by sintering the above powder compact. For example, in the case of a sintered metal material using the above iron-based powder, the above heat treatment can include: carburizing treatment, quenching and tempering, carburizing quenching and tempering, etc. The conditions of the above heat treatment can be appropriately adjusted according to the composition of the sintered metal material. The above heat treatment conditions can adopt well-known conditions.

[0186] The manufacturing method of the above tool body can also include: after the third process, a process of finishing the sintered metal material. Finishing can include, for example, grinding and grinding. By performing finishing, a tool body with excellent surface properties and a tool body with further improved shape accuracy and dimensional accuracy can be obtained.

[0187] (Main effects)

[0188] The manufacturing method of the tool body according to the embodiment can manufacture a tool body made of a sintered metal material. By forming the tool body from a sintered metal material, a tool body with excellent vibration damping properties and stable strength can be obtained. In particular, in the manufacturing method of the embodiment, since the powder compact before sintering is processed into the shape of the tool body, the tool body can be manufactured with good productivity. For example, the tool body according to the above embodiment can be manufactured with good productivity.

[0189] [Test example 1]

[0190] Powder compacts with different relative densities were sintered at various temperatures to produce sintered metal materials, and the microstructure of the sintered metal materials was studied.

[0191] Sintered metal materials were produced by the following method.

[0192] Powder compacts were made using raw material powders.

[0193] The obtained powder compacts were sintered.

[0194] After sintering, carburizing quenching and tempering are carried out in sequence.

[0195] The raw material powder is a mixed powder containing alloy powder composed of the following iron-based alloy and carbon powder.

[0196] The iron-based alloy contains 2% by mass of Ni, 0.5% by mass of Mo, 0.2% by mass of Mn, and the balance is composed of Fe and impurities. The Vickers hardness Hv of this iron-based alloy is 120, which satisfies 80 or more and 200 or less.

[0197] When the total mass of the mixed powder is set to 100% by mass, the content of the carbon powder is 0.3% by mass.

[0198] The average particle size (D50) of the above alloy powder is 100 μm. The average particle size (D50) of the carbon powder is 5 μm.

[0199] The raw material powder is compressed to form an annular compacted powder compact. The compacted powder compact is formed by die stamping. The dimensions of the compacted powder compact are an inner diameter of 16 mm, an outer diameter of 30 mm, and a thickness of 8 mm.

[0200] The forming pressure is selected from the range of 1560 MPa to 1960 MPa so that the relative density (%) of the compacted powder compact of each specimen becomes about 85% to 99%, thereby forming the compacted powder compact. The greater the forming pressure, the easier it is to obtain a compacted powder compact with a high relative density. The density (g / cm 3 ) and relative density (%) of the compacted powder compact of each specimen are shown in Table 1.

[0201] The density (g / cm 3 ) of the compacted powder compact is obtained by measuring the mass of the compacted powder compact and dividing this mass by the volume of the compacted powder compact. The obtained density is the apparent density of the compacted powder compact. The relative density (%) of the compacted powder compact is obtained by dividing the apparent density of the compacted powder compact by the true density of the compacted powder compact. The true density is set to 7.8 g / cm 3 . The true density is obtained based on the composition of the raw material powder.

[0202] The compacted powder compact produced is sintered under the following conditions. After sintering, carburizing quenching is carried out under the following conditions, and then tempering is carried out, thereby obtaining the sintered metal material of each specimen.

[0203] (Sintering conditions)

[0204] The sintering temperature (°C) is any one of 1130 °C, 1450 °C, and 1480 °C. The sintering temperature of each specimen is shown in Table 1. The holding time is 20 minutes. The atmosphere is a nitrogen atmosphere.

[0205] (Carburizing quenching)

[0206]

[0207] (Tempering)

[0208] 200 °C × 90 minutes

[0209] By the above method, a ring-shaped sintered metal material with an inner diameter of 16 mm, an outer diameter of 30 mm, and a thickness of 8 mm was obtained. The matrix phase of this sintered metal material is composed of the following iron-based alloy. This iron-based alloy contains 2% by mass of Ni, 0.5% by mass of Mo, 0.2% by mass of Mn, 0.3% by mass of C, and the balance is composed of Fe and impurities. The composition analysis of the sintered metal material was carried out by ICP.

[0210] (Description of the specimen)

[0211] The sintered metal materials of Specimen Nos. 1 to 3 are sintered metal materials obtained by low-temperature sintering a powder-compacted body with a relative density of 93% or more at a temperature lower than the liquid phase temperature of 1130 °C. Figures 2A to 2C The SEM images obtained by observing an arbitrary cross-section of the sintered metal materials of Specimen Nos. 1 to 3 using a scanning electron microscope (SEM) are shown in sequence.

[0212] The sintered metal materials of Specimen Nos. 101 to 103 are sintered metal materials obtained by high-temperature sintering a powder-compacted body with a relative density of less than 93% at a liquid phase temperature such as 1450 °C or 1480 °C. Figures 8A to 8C The SEM images obtained by observing an arbitrary cross-section of the sintered metal materials of Specimen Nos. 101 to 103 using SEM are shown in sequence. In Figure 8A , Figure 8B , the upper black area is the background. Hereinafter, Figures 8A to 8C will be collectively referred to as Figure 8.

[0213] (Density and relative density)

[0214] The density (g / cm 3 ) and relative density (%) of the sintered metal materials of each specimen produced were studied. The results are shown in Table 1.

[0215] The density (g / cm 3 ) of the sintered metal material was calculated using the results of the above composition analysis.

[0216] The relative density (%) of the sintered metal material was calculated by the following method.

[0217] Obtain a plurality of cross-sections from the sintered metal material. Observe each cross-section using a microscope such as SEM or an optical microscope. Perform image analysis on the observed images, and regard the area ratio of the matrix phase excluding pores as the relative density.

[0218] In the case where the sintered metal material is a cylindrical body or a columnar body, obtain cross-sections from the regions on each end face side of the sintered metal material and the region near the center of the length of the sintered metal material along the axial direction. In the case of this example, the sintered metal material is a cylindrical body. Each end face of the sintered metal material is an annular surface. The axial direction of the sintered metal material corresponds to the thickness direction.

[0219] Although the above-mentioned region on the end face side depends on the above-mentioned length (i.e., thickness) of the sintered metal material, for example, a region within 3 mm from the surface of the sintered metal material toward the inside can be cited. Although the above-mentioned region near the center depends on the above-mentioned length of the sintered metal material, for example, a region from the center of the above-mentioned length toward each end face side up to 1 mm (a total region of 2 mm) can be cited. The cut surface can be cited as a plane intersecting the above-mentioned axial direction, and typically an orthogonal plane can be cited.

[0220] Obtain a plurality of observation fields of view from each cross-section. The number of observation fields of view can be, for example, 10 or more. The size (area) of one observation field of view can be, for example, 500 μm × 600 μm = 300,000 μm 2 . In the case of obtaining a plurality of observation fields of view from one cross-section, preferably, the cross-section is evenly divided, and observation fields of view are obtained from each of the divided regions.

[0221] Perform image processing on the observed images of each observation field of view, and extract the region composed of metal from the processed images. The region composed of metal can be considered as the region obtained by removing pores from the matrix phase. The above-mentioned image processing can be, for example, binarization processing, etc. Calculate the area of the extracted region composed of metal. Further, calculate the ratio of the area of the region composed of metal to the area of the observation field of view. Regard this area ratio as the relative density of each observation field of view. Take the average of the relative densities of the obtained plurality of observation fields of view. Take this average value as the relative density (%) of the sintered metal material.

[0222] Here, obtain 10 or more observation fields of view from each of the two regions on the end face side. In addition, obtain 10 or more observation fields of view from the region near the center. Then, calculate the relative density of each observation field of view, and take the average of a total of 30 or more relative densities. Take this average value as the relative density (%) of the sintered metal material.

[0223] It should be noted that the relative density of the compacted powder compact can be obtained in the same manner as the relative density of the sintered metal material described above. As in this example, in the case where the compacted powder compact is formed by die stamping, cross-sections of the compacted powder compact can be obtained from a region near the center of the length of the compacted powder compact along the pressing axis and from regions on the end face sides at both ends of the pressing axis, respectively. The cut surface can be a plane intersecting the pressing axis, and typically an orthogonal plane can be cited.

[0224] (Microstructure observation)

[0225] For the sintered metal materials of each specimen produced, arbitrary cross-sections were obtained and the sizes of the pores were studied.

[0226] The sizes of the pores were obtained by the following method.

[0227] Arbitrary cross-sections were obtained from the sintered metal materials of each specimen. The above cross-sections were observed by SEM and at least 1 field of view was obtained from the above cross-sections. A total of 50 or more pores were extracted for the measurement of the pore sizes.

[0228] Here, the size of the field of view was adjusted so that there were 50 or more pores in 1 field of view. The size of 1 field of view was approximately 355 μm × approximately 267 μm.

[0229] The pores were extracted from the above field of view. As shown in FIGS. 2 and 8, the color of the matrix 10 is different from the color of the pores 11. Therefore, the pores can be extracted by performing image processing such as binarization processing on the SEM image. A commercially available image analysis system or commercially available image analysis software can be used to extract the pores and measure the pore sizes, extract the metal - composed region for the measurement of the above relative density, measure the area of the above region, etc.

[0230] 〈Cross-sectional area〉

[0231] The cross-sectional areas of the respective pores extracted from the above SEM image were obtained. Further, the average value of the cross-sectional areas of the pores was obtained. The average value of the above cross-sectional areas was obtained by the following method: obtaining the sum of the cross-sectional areas of 50 or more pores extracted from 1 field of view and dividing the sum by the number of pores. The average value of the above cross-sectional areas was taken as the average cross-sectional area (μm 2 ). The average cross-sectional areas are shown in Table 1. In addition, the number of pores (N number) extracted is shown in Table 1.

[0232] 〈Perimeter〉

[0233] Find the perimeter of each pore extracted from the above SEM image. The perimeter of a pore is the length of the pore's contour. Further, find the average value of the perimeters of the pores. The average value of the above perimeters is obtained by the following method: find the sum of the perimeters of 50 or more pores extracted, and divide the sum by the number of pores. Take the average value of the above perimeters as the average perimeter (μm). The above average perimeter is shown in Table 1.

[0234] 〈Maximum diameter〉

[0235] Find the maximum diameter of each pore extracted from the above SEM image. Further, find the average value of the maximum diameters. The average value of the above maximum diameters is obtained by the following method: find the sum of the maximum diameters of 50 or more pores extracted, and divide the sum by the number of pores. The average value of the above maximum diameters (μm) is shown in Table 1. The maximum diameter of a pore is obtained by the following method. In the above SEM image, the contour of each pore is sandwiched between two parallel lines, and measure the distance between these two parallel lines. The above distance is the distance in the direction orthogonal to the above parallel lines. Take multiple sets of parallel lines in an arbitrary direction and measure the above distance respectively. Take the maximum value among the multiple measured above distances as the maximum length of each pore, and take this maximum length as the maximum diameter.

[0236] Find the maximum value and minimum value of the maximum diameter of the pores. Here, the maximum value (μm) among the maximum diameters of the above 50 or more pores is shown in Table 1. In addition, the minimum value (μm) among the maximum diameters of the above 50 or more pores is shown in Table 1.

[0237] 〈Circularity〉

[0238] In addition, find the circularity of the pores. To find the circularity, first, for all pores existing in 4 or more fields of view in an arbitrary cross-section of the sintered metal material, find the diameter of the circumscribed circle and the diameter of the inscribed circle of each pore. Then, find the ratio of each pore "diameter of the circumscribed circle of the pore / diameter of the inscribed circle of the pore". Set the circularity as the average of the above ratios of all pores. The diameters of the circumscribed circle and the inscribed circle of the pore can be obtained using commercially available image analysis software. Observe the cross-section using SEM. Set the magnification of each field of view to 450 times. Set the size of each field of view to 0.4 mm × 0.6 mm. The above circularity is shown in Table 1.

[0239] [Table 1]

[0240]

[0241] Figures 3 to 7 In turn, show the average cross-sectional area (μm of the pores in the sintered metal material of each specimen 2)、Graphs of the average perimeter of pores (μm), average value of the maximum diameter of pores (μm), maximum value of the maximum diameter of pores (μm), and minimum value of the maximum diameter of pores (μm). The horizontal axis of each graph represents the sample number. For the vertical axis of each graph, in Figure 3 it represents the average cross-sectional area of pores (μm 2 ), in Figure 4 it represents the average perimeter of pores (μm), in Figure 5 it represents the average value of the maximum diameter of pores (μm), in Figure 6 it represents the maximum value of the maximum diameter of pores (μm), and in Figure 7 it represents the minimum value of the maximum diameter of pores (μm).

[0242] As shown in Table 1 and Figure 3 , it can be seen that: compared with the sintered metal materials of Samples No. 101 to No. 103, the average cross-sectional area of pores in the sintered metal materials of Samples No. 1 to No. 3 is smaller. Hereinafter, the sintered metal materials of Samples No. 1 to No. 3 are referred to as samples of high-density forming. In addition, the sintered metal materials of Samples No. 101 to No. 103 are referred to as samples of high-temperature sintering. Quantitatively, the average cross-sectional area of pores in the samples of high-density forming is 500 μm 2 or less, and particularly 450 μm 2 or less in this example. In the sintered metal materials of Samples No. 2 and No. 3 with a relative density of the sintered metal material of 96.5% or more, the average cross-sectional area of pores is 400 μm 2 or less, particularly 300 μm 2 or less. The average cross-sectional area of pores in the sintered metal materials of Samples No. 2 and No. 3 is even smaller.

[0243] In addition, as shown in Table 1 and Figure 4 , it can be seen that: compared with the samples of high-temperature sintering, the average perimeter of pores in the samples of high-density forming is shorter. Quantitatively, the average perimeter of pores in the samples of high-density forming is 100 μm or less, and particularly 70 μm or less in this example. The average perimeter of pores in the sintered metal materials of Samples No. 2 and No. 3 is 55 μm or less. The average perimeter of pores in the sintered metal materials of Samples No. 2 and No. 3 is even shorter.

[0244] In the samples of high-temperature sintering, the relative density of the sintered metal material is 93% or more, as shown in Table 1 and Figures 8A to 8CAs shown, the cross-sectional area of each pore 11 is relatively large and the perimeter is relatively long. One of the reasons is considered to be as follows. Compared with the compacted powder compact used for the specimens of high-density forming, the relative density of the compacted powder compact used for the specimens of high-temperature sintering is smaller, and thus a large number of pores are included. When sintering a compacted powder compact with many pores at a high temperature such as the liquid-phase temperature, although the bubbles are somewhat easily discharged, multiple bubbles combine inside. Therefore, as Figures 8A to 8C shown, large pores tend to remain in the specimens of high-temperature sintering. That is, pores with a large cross-sectional area and a long perimeter tend to remain.

[0245] In contrast, as shown in Table 1 and Figures 2A to 2C shown, in the specimens of high-density forming, although the number of pores 11 is somewhat larger, the cross-sectional area of each pore 11 is smaller and the perimeter is shorter. Among the sintered metal materials of Specimens No. 1 to No. 3, the number of pores 11 in Specimen No. 3 is the smallest, and the cross-sectional area of the pores 11 is the smallest and the perimeter is the shortest. One of the reasons is considered to be as follows. The relative density of the compacted powder compact used for the specimens of high-density forming is large, and thus the number of pores is small. In addition, through compression, each pore easily becomes smaller. When sintering such a compacted powder compact at a relatively low temperature, although the bubbles do not discharge and tend to remain, each pore is still small. Therefore, as Figures 2A to 2C shown, in the specimens of high-density forming, pores with a small cross-sectional area and a short perimeter tend to remain. In addition, the fewer the pores in the compacted powder compact, the easier it is for the cross-sectional area of the pores in the sintered metal material to become smaller, and at the same time the easier it is for the perimeter of the pores to become shorter.

[0246] In addition, the following can be known from this experiment.

[0247] (1) As shown in Table 1 and Figure 5 shown, the average value of the maximum diameter of the pores in the specimens of high-density forming is smaller than that in the specimens of high-temperature sintering. Quantitatively, the average value of the above-mentioned maximum diameter in the specimens of high-density forming is 30 μm or less, and particularly 20 μm or less in this example. In addition, the average value of the above-mentioned maximum diameter in the specimens of high-density forming is 5 μm or more, and particularly 10 μm or more in this example. Although such pores are small, it can be considered that they are not too small.

[0248] (2) As shown in Table 1 and Figure 6 、 Figure 7As shown, compared with the specimens sintered at high temperature, the maximum and minimum values of the maximum diameter of the pores in the specimens formed with high density are also smaller. Quantitatively, the maximum value of the above-mentioned maximum diameter in the specimens formed with high density is 30 μm or less, and particularly 25 μm or less in this example. In addition, compared with the specimens sintered at high temperature, the difference between the average value and the maximum value of the above-mentioned maximum diameter in the specimens formed with high density is smaller. Therefore, it can be considered that the pores have a uniform size in the specimens formed with high density. The minimum value of the above-mentioned maximum diameter in the specimens formed with high density is 20 μm or less, and particularly 5 μm or more and 15 μm or less in this example. From this, it can be seen that although the pores are small in the specimens formed with high density, it can be considered that they are not too small.

[0249] (3) As shown in Table 1, compared with the specimens sintered at high temperature, the roundness of the pores in the specimens formed with high density is smaller. Quantitatively, the roundness of the pores in the specimens formed with high density is 3.4 or less, and further 3.3 or less here.

[0250] In addition, this experiment shows that a sintered metal material with a relative density of 93% or more and 99.5% or less and small pores can be manufactured by sintering a green compact with a relative density of 93% or more and 99.5% or less at a relatively low temperature below the liquid phase temperature. In addition, it is shown that by using a powder composed of an iron-based alloy with a Vickers hardness Hv of 80 or more and 200 or less, a dense green compact as described above can be obtained.

[0251] As described above, in a sintered metal material with a high relative density, high density and small pores, it is difficult for the pores to become the starting point of cracking, so the strength is excellent. Therefore, the above-mentioned sintered metal material can be expected to be suitable for various components requiring high strength, etc. As a specific example of the above components, the main body of a cutting tool can be cited. The above-mentioned sintered metal material can effectively suppress vibration or effectively dissipate heat through a plurality of pores. Therefore, the above-mentioned sintered metal material can be suitable for the main body of a cutting tool that expects vibration damping and heat dissipation.

[0252] [Test Example 2]

[0253] Manufacture a tool body made of a sintered metal material and evaluate it.

[0254] The tool body is manufactured by the following method.

[0255] Use raw material powder to form a green compact.

[0256] Process the green compact into the shape of a tool body.

[0257] Sinter the processed green compact.

[0258] After sintering, perform carburizing quenching and tempering in sequence.

[0259] The raw material powder is the same as that in Test Example 1 above. That is, the raw material powder is a mixed powder containing alloy powder composed of an iron-based alloy containing 2% by mass of Ni, 0.5% by mass of Mo, and 0.2% by mass of Mn and carbon powder. When the total mass of the mixed powder is set to 100% by mass, the content of the carbon powder is 0.3% by mass.

[0260] The raw material powder was compressed to form a cylindrical compacted powder compact. The forming of the compacted powder compact was carried out by die stamping. The forming pressure of the compacted powder compact in each specimen was the same as that of the sintered metal materials of Specimen Nos. 1 to 3 in Test Example 1 above. The density (g / cm 3 ) and relative density (%) of each specimen are shown in Table 2. The density (g / cm 3 ) and relative density (%) of the compacted powder compact were determined in the same manner as in Test Example 1.

[0261] The fabricated compacted powder compact was machined to form the shape of the tool body. In this example, it was machined into the shape of the tool body of the cutting tool shown in Figure 1A . The cutting tool is "SECWaveMill WEX2000F" manufactured by Sumitomo Electric Industries, Ltd., and the cutting edge diameter is 40 mm.

[0262] After machining, the sintered compacted powder compact was sintered. After sintering, carburizing quenching and tempering were carried out to obtain the tool bodies of the respective specimens. The sintering temperature was set to 1130°C, which is the same as that of Specimen Nos. 1 to 3 above. The conditions of carburizing quenching and tempering were the same as those of Specimen Nos. 1 to 3 above.

[0263] For the sintered metal materials constituting the tool bodies of the respective specimens obtained by the above method, the composition of the matrix phase was analyzed by ICP. As a result, the composition of the matrix phase of the sintered metal material was: an iron-based alloy containing 2% by mass of Ni, 0.5% by mass of Mo, 0.2% by mass of Mn, 0.3% by mass of C, and the balance being Fe and impurities.

[0264] (Description of specimens)

[0265] The sintered metal materials constituting the tool bodies of Specimen Nos. 21 to 23 were obtained by sintering compacted powder compacts with a relative density of 93% or more at a low temperature of 1130°C, which is lower than the liquid phase temperature. For the tool bodies of Specimen Nos. 21 to 23, an arbitrary cross-section was observed in the same manner as in Specimen Nos. 1 to 3 above using a scanning electron microscope (SEM).

[0266] (Density and relative density)

[0267] The density (g / cm 3 ) and relative density (%) of the sintered metal material that constitutes the tool body of each specimen were studied. The density (g / cm 3 ) and relative density (%) of the sintered metal material of each specimen are shown in Table 2. The density (g / cm 3 ) and relative density (%) of the sintered metal material were determined in the same manner as in Test Example 1 above.

[0268] (Microstructure Observation)

[0269] For the sintered metal material that constitutes the tool body of each specimen, an arbitrary cross-section was obtained, and the above cross-section was observed using SEM to extract pores, thereby studying the size of the pores. The size of the pores in the sintered metal material of each specimen was measured in the same manner as in Specimens Nos. 1 to 3 above. The average cross-sectional area (μm 2 ), average perimeter (μm) of the pores, average value of the maximum diameter (μm) of the pores, maximum value of the maximum diameter (μm) of the pores, and minimum value of the maximum diameter (μm) of the pores in the sintered metal material of each specimen are shown in Table 2.

[0270] [Table 2]

[0271]

[0272] Blades were installed on the tool bodies of Specimens Nos. 21 to 23 to assemble cutting tools. Then, the tool bodies of each specimen were used for cutting tools and cutting operations were performed. The blades used were AXMT123504PEER-G manufactured by Sumitomo Electric Industries, Ltd. The material type of the blades was cemented carbide. In the cutting operation, the end face of a cylinder as the workpiece material was cut using the above cutting tool. The material of the workpiece was SCM440. The diameter of the cylinder was 75 mm. The length of the cylinder was 30 mm. The cutting conditions are as follows.

[0273] (Cutting Conditions)

[0274] Cutting speed: 100 m / min

[0275] Feed rate: 0.4 mm / t

[0276] Depth of cut: 3 mm

[0277] Cutting environment: Dry

[0278] The above feed rate is the feed rate per edge.

[0279] For comparison, a tool body made of a melted material was prepared. The prepared tool body is a tool holder for milling, and was made by cutting from a melted material of SKD61. The shape of this tool body is the same as the tool bodies of the above-mentioned Specimens No. 21 to No. 23. The above-mentioned tool body made of a melted material was used as Specimen No. 200.

[0280] An arbitrary cross-section of the tool body of Specimen No. 200 was observed using SEM. As a result, there are substantially no pores in the melted material constituting the tool body of Specimen No. 200. That is, the relative density of the melted material constituting the tool body of Specimen No. 200 is substantially 100%.

[0281] A cutting blade was installed on the tool body of Specimen No. 200, and cutting was performed under the same conditions as those of the above-mentioned Specimens No. 21 to No. 23.

[0282] (Evaluation of machining accuracy)

[0283] The machining accuracy when using the tool bodies of Specimens No. 21 to No. 23 and the tool body of Specimen No. 200 respectively was evaluated. The machining accuracy was evaluated by the surface roughness of the end face of the machined material after machining. It can be considered that the smaller the surface roughness of the machined surface, the higher the machining accuracy. In this example, the surface roughness in the radial direction of the end face of the machined material was measured. The measured surface roughness was the arithmetic mean roughness Ra. The measurement of the surface roughness was carried out according to JIS B 0601-2001, with the reference length set to 0.1 mm and the evaluation length set to 2.0 mm. As a result, in the tools using the tool bodies of Specimens No. 21 to No. 23, the arithmetic mean roughness Ra in the radial direction of the end face of the machined material was all 1 μm or less. In contrast, in the tool using the tool body of Specimen No. 200, the arithmetic mean roughness Ra in the radial direction of the end face of the machined material was 3 μm.

[0284] As described above, compared with the case of using the tool body of Specimen No. 200, the surface roughness of the end face of the machined material is smaller when using the tool bodies of Specimens No. 21 to No. 23. From this, it can be seen that when using the tool bodies of Specimens No. 21 to No. 23, it is excellent in terms of machining accuracy. It is considered that the reason is as follows. The tool bodies of Specimens No. 21 to No. 23 are made of sintered metal materials, so vibrations can be effectively suppressed by the multiple pores in the sintered metal materials. That is, the vibration damping property of the tool bodies of Specimens No. 21 to No. 23 is excellent. From this, it can be considered that when using the tool bodies of Specimens No. 21 to No. 23, by suppressing chatter and the like generated during machining, the machining accuracy can be improved.

[0285] The following study was conducted on each cutting tool with the tool body using Specimens No. 21 to No. 23: Whether cracks or notches occurred in the tool body after repeating the above cutting process 1,000 times. As a result, no damage such as cracks was confirmed in any of the tool bodies. From this, it can be seen that the tool bodies of Specimens No. 21 to No. 23 have a sufficiently high strength.

[0286] Explanation of symbols

[0287] 1 Sintered metal material

[0288] 10 Matrix phase

[0289] 11 Pores

[0290] 100, 200 Tools

[0291] 101, 201 Blades

[0292] 102, 202 Cutting edges

[0293] 103, 203 Through holes

[0294] 110, 210 Tool bodies

[0295] 111, 211 Mounting seats

Claims

1. A tool body, which is a tool body for installing a blade, The tool body is made of a sintered metal material, The sintered metal material has: A matrix phase composed of metal, and A plurality of pores existing in the matrix phase, The relative density of the sintered metal material is 93% or more and 99.5% or less, In any cross-section of the sintered metal material, the average perimeter of the pores is 100 μm or less, the average cross-sectional area of the pores is 500 μm 2 Hereinafter, the average value of the maximum diameter of the pores is 5 μm or more and 30 μm or less.

2. The tool body according to claim 1, wherein The plurality of pores are isotropically dispersed in the matrix phase.

3. The tool body according to claim 1 or 2, wherein The metal is an iron-based alloy, The iron-based alloy contains one or more elements selected from the group consisting of C, Ni, Mo, and B.

4. A method for manufacturing a tool body, which is a method for manufacturing the tool body according to any one of claims 1 to 3, including: A step of compressing a raw material powder containing metal powder to form a compacted body; A step of machining the compacted body into the shape of a tool body to which a blade is to be mounted; and A step of sintering the compacted body machined into the shape of the tool body, In the step of sintering the compacted body, the sintering temperature is 1000 °C or higher and less than 1300 °C.

5. The method for manufacturing a tool body according to claim 4, wherein In the step of producing the compacted body, the relative density of the compacted body is 85% or higher and 99.9% or lower.

6. The method for manufacturing a tool body according to claim 4, wherein The metal powder contains powder composed of an iron-based material having a Vickers hardness Hv of 80 or higher and 200 or lower.

7. The method for manufacturing a tool body according to claim 5, wherein The metal powder contains powder composed of an iron-based material having a Vickers hardness Hv of 80 or higher and 200 or lower.

8. The method for manufacturing a tool body according to claim 6 or 7, wherein The powder composed of the iron-based material contains powder composed of an iron-based alloy, The iron-based alloy contains at least one of Mo in an amount of 0.1% by mass or more and 2.0% by mass or less and Ni in an amount of 0.5% by mass or more and 5.0% by mass or less.

Images