Sintered part and process for manufacturing a sintered part

Abstract

Sintered part consisting of a metal, wherein the sintered part has a relative density of 95% or more and has at least one of a hole for which the diameter x1 and depth y1 meet specific requirements, and a groove for which the width x2 and depth y2 meet specific requirements.

Description

TECHNICAL FIELD

[0001] The present invention relates to a sintered compact and a method for producing a sintered compact.

[0002] This application claims priority from Japanese Patent Application No. 2022-071901, filed on April 25, 2022, the entire contents of which are incorporated herein by reference. BACKGROUND

[0003] A method for producing a sintered compact in PTL 1 includes the step of press-molding a raw material powder to produce a green compact, the step of forming a hole in the green compact, and the step of sintering the green compact with the hole formed therein. The raw material powder contains iron powder, copper powder, carbon powder, and ethylene bisstearamide. LIST OF CITATIONSPATENT LITERATURE

[0004] PTL 1: Unexamined Japanese patent application with publication number 2019-14971 SUMMARY OF THE INVENTION

[0005] The sintered compact of the present invention is a sintered compact formed of a metal, the sintered compact having a relative density of 95% or more, the sintered compact having at least one of a hole having a diameter x1 (mm) and a depth y1 (mm) and a groove having a width x2 (mm) and a depth y2 (mm), the diameter x1 and the depth y1 satisfying the following requirements (a1) to (a7), the width x2 and the depth y2 satisfying the following requirements (b1) to (b3): if 0.05≤×1<0.08,y1>2.67×1+0.217; if 0.08≤×1<0.1,y1>28.5×1−1.85; if 0,1≤×1<0,3,y1>10×1; if 0.3≤×1<0.8,y1>8×1+0.6; if 0.8≤×1<1.5,y1>32.9×1−19.3; if 1.5≤x1<2.0,y1>20x1; if 2,0≤x12,y1>10×1+20; if 0.05≤×2<0.2,y2>5×2+0.4; if 0.2≤×<0.5,y2>28.7×2−4.3;and if 0.5≤×2,y2>6×2+7.

[0006] The process for producing sintered molded parts according to the present invention comprises: Preparing a raw material powder containing a metal powder and a lubricant; pressing the raw material powder to produce a green compact with a relative density of 95% or more; Subjecting the green compact to at least one cutting process selected from hole drilling and grooving to produce a workpiece having at least one of a hole with a diameter x1 (mm) and a depth y1 (mm) and a groove with a width x2 (mm) and a depth y2 (mm), wherein the diameter x1 and the depth y1 satisfy the requirements (a1) to (a7) below, wherein the width x2 and the depth y2 satisfy the requirements (b1) to (b3) below; and

[0007] Sintering of the workpiece, wherein the proportion of lubricant contained in the raw material powder is 0.025 mass percent to 0.2 mass percent, and wherein the lubricant has a melting point of 150°C or less: if 0.05≤x1<0.08,y1>2.67x1+0.217; if 0.08≤x1<0.1,y1>28.5x1−1.85; if 0,1≤x1<0,3,y1>10x1 if 0.3≤x1<0.8y1>8x1+0.6; if 0.8≤x1<1.5,y1>32.9x1−19.3; if 1.5≤x1<2.0,y1>20x1 if 2,0≤x1,y1>10x1+20; if 0.05≤x2<0.2,y2>5x2+0.4; if 0.2≤x2<0.5, y2>28.7x2−4.3; and if 0.5≤x2, y2>6x2+7. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic perspective view showing a sintered molded article in one embodiment. Fig. 2 is a cross-sectional view along the line II-II in Fig. 1. Fig.3 is a partial cross-sectional view showing another example of the sintered molded article in this embodiment. Fig. 4 is a cross-sectional view along the line IV-IV in Fig. 3. Fig. Figure 5 is a graph showing the relationship between the diameter and depth of the holes in each of the sintered compacts prepared in Test Example 1. Fig. Figure 6 is an enlarged view of area A in Fig. 5. Fig. Figure 7 is an enlarged view of area B in Fig. 6. Fig. Figure 8 is a graph showing the relationship between the width and depth of the grooves in each of the sintered compacts prepared in Test Example 2. Fig. Figure 9 is an enlarged view of area C in Fig. 8. DETAILED DESCRIPTION [Problems to be solved by the present invention]

[0008] There is a need to produce a sintered part that has a hole with a large depth relative to its diameter or a groove with a large depth relative to its width.

[0009] An object of the present invention is to provide a sintered compact having a hole with a large depth relative to its diameter or a groove with a large depth relative to its width. Another object of the present invention is to provide a method for producing the sintered compact. [Advantageous effects of the present invention]

[0010] The sintered compact of the present invention has a hole with a large depth relative to its diameter or a groove with a large depth relative to its width. The method for producing the sintered compact according to the present invention can produce the sintered compact of the present invention. <<Beschreibung von Ausführungsformen der vorliegenden Erfindung> >

[0011] First, embodiments of the present invention are enumerated and described.

[0012] (1) One embodiment of the sintered molding of the present invention is a sintered molding formed of a metal, wherein the sintered molded article has a relative density of 95% or more, wherein the sintered molded part has at least one of a hole with a diameter x1 (mm) and a depth y1 (mm) and a groove with a width x2 (mm) and a depth y2 (mm), wherein the diameter x1 and the depth y1 satisfy the following requirements (a1) to (a7), wherein the width x2 and the depth y2 satisfy the following requirements (b1) to (b3): if 0.05≤x1<0.08, y1>2.67x1+0.217; if 0.08≤x1<0.1, y1>28.5x1−1.85; if 0.1≤x1<0.3, y1>10x1; if 0.3≤x1<0.8, y1>8x1+0.6; if 0.8≤x1<1.5, y1>32.9x1−19.3; if 1.5≤x1<2.0, y1>20x1; if 2,0≤x1, y1>10×1+20; if 0.05≤x2<0.2, y2>5x2+0.4; if 0.2≤x2<0.5, y2>28.7x2−4.3; and if 0.5≤x2,y2>6x2+7.

[0013] The sintered part has the hole with a large depth relative to its diameter or the groove with a large depth relative to its width.

[0014] (2) In the sintered molded part according to (1), the metal may be pure iron or an iron alloy.

[0015] The sintered part made of pure iron or an iron alloy has the hole with a large hole depth relative to its diameter or the groove with a large depth relative to its width.

[0016] (3) In the sintered molded part according to (1), the metal may be stainless steel.

[0017] The sintered stainless steel part has the hole with a large depth relative to its diameter or the groove with a large depth relative to its width.

[0018] (4) A method for producing a sintered compact according to an embodiment of the present invention comprises: preparing a raw material powder comprising a metal powder and a lubricant; pressing the raw material powder to produce a green compact having a relative density of 95% or more; Subjecting the green compact to at least one cutting process selected from hole drilling and groove milling to produce a workpiece having at least one of a hole with a diameter x1 (mm) and a depth y1 (mm) and a groove with a width x2 (mm) and a depth y2 (mm), wherein the diameter x1 and the depth y1 satisfy the following requirements (a1) to (a7), wherein the width x2 and the depth y2 satisfy the following requirements (b1) to (b3); and sintering of the workpiece, wherein the proportion of lubricant contained in the raw material powder is 0.025 mass percent to 0.2 mass percent, and wherein the lubricant has a melting point of 150°C or less: if 0.05≤x1<0.08, y1>2.67x1+0.217; if 0.08≤x1<0.1, y1>28.5x1−1.85; if 0,1≤x1<0,3,y1>10x1; if 0.3≤x1<0.8,y1>8x1+0.6; if 0.8≤x1<1.5,y1>32.9x1−19.3; if 1.5≤x1<2.0,y1>20x1; if 2,0≤x1,y1>10x1+20; if 0.05≤x2<0.2,y2>5x2+0.4; if 0.2≤x2<0.5,y2>28.7x2−4.3; and if 0.5≤x2,y2>6x2+7.

[0019] In the method for producing sintered compacts described above, the raw material powder containing the lubricant with a melting point of 150°C or less is compressed, which allows the lubricant to easily disperse into the spaces between the particles of the produced green compact. Because the lubricant is dispersed in the spaces between the particles of the green compact, the hole can be formed by drilling the green compact and the groove can be formed by grooving the green compact. The specific gravity of the green compact is equal to the specific gravity of the workpiece. Since the specific gravity of the produced green compact is 95% or more, shrinkage during sintering of the workpiece is very small. Therefore, the dimensions of the hole and groove in the workpiece are maintained and are essentially the same as the dimensions of the hole and groove in the sintered compact.With the method for producing a sintered molding described above, a sintered molding having a hole with a large depth relative to its diameter or having a groove with a large depth relative to its width can be produced.

[0020] (5) In the method for producing a sintered molded article according to (4), the lubricant may be stearic acid, erucic acid amide or stearic acid amide.

[0021] By pressing the raw material powder, the lubricant can be easily and widely distributed into the interstices of the particles in the green body. < <details zu ausführungsformen der vorliegenden erfindung>>

[0022] Embodiments of the present invention are described with reference to the drawings. In the drawings, like reference numerals denote components with like names. The dimensions of the molded parts shown in the drawings are provided for clarity of description and do not necessarily represent actual dimensions. <<Ausführungsformen> >[sintered molded part]

[0023] With reference to the Fig. 1 to 4, a sintered compact 1 is described in one embodiment. The sintered compact 1 is made of a metal. A feature of the sintered compact 1 in the present embodiment is that the sintered compact 1 has a high relative density and has a hole 2 of a specific size and / or a groove 3 of a specific size. [Material]

[0024] The material of the sintered molded part 1 is a metal. The metal is, for example, pure iron, an iron alloy, or a non-ferrous metal.

[0025] Pure iron is iron with a purity of 99% or more. Specifically, pure iron is a material with an iron (Fe) content of 99% or more by mass.

[0026] An iron alloy is an alloy that contains an additional element, with the remainder consisting of iron (Fe) and unavoidable impurities. The iron alloy contains the highest amount of Fe. The additional element contained in an iron alloy is, for example, at least one element from the group consisting of nickel (Ni), copper (Cu), chromium (Cr), molybdenum (Mo), manganese (Mn), carbon (C), silicon (Si), aluminum (Al), phosphorus (P), boron (B), nitrogen (N), and cobalt (Co).Specific examples of iron alloys include stainless steel, Fe-C-based alloys, Fe-Cu-Ni-Mo-based alloys, Fe-Ni-Mo-Mn-based alloys, Fe-P-based alloys, Fe-Cu-based alloys, Fe-Cu-C-based alloys, Fe-Cu-Mo-based alloys, Fe-Ni-Mo-Cu-C-based alloys, Fe-Ni-Cu-based alloys, Fe-Ni-Mo-C-based alloys, Fe-Ni-Cr-based alloys, Fe-Ni-Mo-Cr-based alloys, Fe-Cr-based alloys, Fe-Mo-Cr-based alloys, Fe-Cr-C-based alloys, Fe-Ni-C-based alloys, and Fe-Mo-Mn-Cr-C-based alloys. Examples of stainless steel include austinite stainless steel. Examples of austenitic stainless steel are SUS304 and SUS304L.

[0027] The non-ferrous metal is, for example, copper, a copper alloy, aluminum or an aluminum alloy.

[0028] The composition of the sintered molded part 1 can be checked by analyzing the composition using ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry). [Relative density]

[0029] The relative density of the sintered compact 1 is 95% or more. The sintered compact 1 with a relative density of 95% or more has good mechanical properties such as strength. The relative density of the sintered compact 1 may be 96% or more, especially 97% or more. There are no particular restrictions on the upper limit of the relative density of the sintered compact 1, and the upper limit can be reasonably selected as long as the sintered compact 1 can be manufactured. For example, the relative density of the sintered compact 1 may be 99.9% or less. In particular, the relative density of the sintered compact 1 may be 95% to 99.9%, 96% to 99.9%, especially 97% to 99.9%.

[0030] The relative density of the sintered part 1 is the ratio (%) between the actual density of the sintered part 1 and the true density of the sintered part 1. Specifically, the relative density of the sintered part 1 is determined as [(actual density of the sintered part 1) / (true density of the sintered part 1)) × 100]. The true density of the sintered part 1 can be determined by immersing the sintered part 1 in oil to impregnate the sintered part 1 with the oil and calculating [oil-impregnated density × (mass of the sintered part 1 before oil impregnation) / (mass of the sintered part 1 after oil impregnation)]. The oil-impregnated density is defined as (mass of the sintered part 1 after impregnation with oil / volume of the sintered part 1 after impregnation with oil).Specifically, the true density of the sintered part 1 can be determined as (mass of the sintered part 1 before oil impregnation / volume of the sintered part 1 after oil impregnation). The volume of the sintered part 1 after oil impregnation can typically be measured by a liquid displacement method. The true density of the sintered part 1 is a theoretical density determined from the composition of the sintered part 1, assuming that the sintered part 1 contains no voids. [Hole]

[0031] Hole 2 is either a through hole or a blind hole. The blind hole has a bottom. The number of holes 2 is not limited and can be freely selected. If the number of holes 2 is two or more, the holes 2 can include both a through hole and a blind hole. Hole 2 has a substantially uniform diameter in a direction along the depth of hole 2.

[0032] The diameter x1 (mm) and depth y1 (mm) of hole 2 meet the following requirements (a1) to (a7). The details of the requirements are given in Test Example 1 with reference to the Fig. 5 to 7. If 0.05≤x1<0.08, y1>2.67x1+0.217. If 0.08≤x1<0.1,y1>28.5x1−1.85. If 0,1≤x1<0,3,y1>10x1. If 0.3≤x1<0.8,y1>8x1+0.6. If 0.8≤x1<1.5,y1>32.9x1−19.3. If 1.5≤x1<2.0,y1>20x1. If 2,0≤x1,y1>10x1+20.

[0033] The upper limit of the depth y1 (mm) of hole 2 relative to the diameter x1 (mm) depends, for example, on the limit of the tool diameter and the limit of its length or the limit of the size of the green compact during its manufacturing process. For example, for a commercially available drill used to produce hole 2, the ratio L / D between the length of the flute L (mm) of the drill and the diameter D (mm) of the drill is about 20 or less, or about 30 or less. The limit of the ratio L / D depends on the diameter D and the material of the tool, but should be 40 or less, or 50 or less, even for special drills used for drilling particularly deep holes. For example, for all requirements (a1) to (a7), the upper limit of the depth y1 of hole 2 relative to the diameter x1 is at least 50 times the diameter x1.It is considered that the depth of the hole 2 formed by a later-described method for manufacturing the sintered compact in the present embodiment may be greater than the depth of a hole that can be formed with a drill with L / D = 50, which is the manufacturing limit of the drill. [Nut]

[0034] The number of grooves 3 is not limited and can be selected accordingly. Groove 3 has a substantially uniform width in one direction along the depth of groove 3.

[0035] The width x2 (mm) and depth y2 (mm) of groove 3 meet the following requirements (b1) to (b3). The details of the requirements are shown in Test Example 2 with reference to the Fig. 8 and Fig. 9 described. If 0.05≤x2<0.2,y2>5x2+0.4. If 0.2≤x2<0.5, y2>28.7x2−4.3. If 0.5≤x2, y2>6x2+7.

[0036] The upper limit of the depth y2 (mm) of the groove 3 relative to its width x2 (mm) depends, for example, on the limit of the width of the tool or the limit of the size of the green compact during the manufacturing process.

[0037] The sintered molded part 1 can have both the hole 2 and the groove 3, which are not shown. [Method for producing a sintered molded part]

[0038] A method for manufacturing a sintered compact according to an embodiment includes: step A of preparing a raw material powder; step B of producing a green compact; step C of producing a workpiece; and step D of sintering the workpiece. A feature of the manufacturing method for the sintered compact is that the specific raw material powder is prepared in step A, and the specific hole and / or groove is formed in step C. With the manufacturing method for the sintered compact according to the embodiment, the above-described sintered compact 1 is manufactured. [Step A: Preparing a raw material powder]

[0039] In step A, the raw material powder, which contains a metal powder and a lubricant, is prepared. The raw material powder does not contain an organic binder. The metal powder is, for example, a ferrous powder or a non-ferrous powder. (iron-containing powder)

[0040] The iron powder is a powder selected from the group consisting of a pure iron powder, a first iron alloy powder, a first powder mixture, a second powder mixture, a third powder mixture, and a fourth powder mixture. The pure iron contained in the pure iron powder has a purity of 99% or more, as described above. The first iron alloy contained in the first iron alloy powder is the iron alloy described above. The first powder mixture consists of the pure iron powder and an alloying element powder. The alloying element powder is a powder of an element used to produce the iron alloy in step D. The alloying element is an additional element of the iron alloy described above.When the manufactured sintered part 1 is formed from an iron alloy comprising a plurality of additional elements, the alloying element powder comprises a plurality of additional element powders. The second powder mixture is composed of a second iron alloy powder and a carbon powder. Examples of the second iron alloy contained in the second iron alloy powder are Fe-Cu base alloys, Fe-Ni-Mo-Cu base alloys, Fe-Ni-Mo base alloys, Fe-Cr base alloys, Fe-Ni base alloys, and Fe-Mo-Mn-Cr base alloys. The third powder mixture is composed of the pure iron powder, the alloy powder, and the first iron alloy powder. The fourth powder mixture consists of the pure iron powder, the alloying element powder, the second iron alloy powder, and a carbon powder. (Non-ferrous powder)

[0041] The non-ferrous powder is a copper powder, a copper alloy powder, an aluminum powder or an aluminum alloy powder. (Lubricant)

[0042] The lubricant disperses into the interstices between a plurality of particles under the processing heat generated during the pressing of the raw material powder in step B. Such a lubricant has a melting point of 150°C or lower. The melting point of the lubricant may be 110°C or lower, particularly 85°C or lower. For example, the melting point of the lubricant is 50°C or higher. Specifically, the melting point of the lubricant may be 50°C to 150°C, 55°C to 110°C, particularly 60°C to 85°C. Specific examples of the lubricant are stearic acid, erucic acid amide, and stearic acid amide. These lubricants can easily and widely disperse into the interstices between the plurality of particles under the processing heat in step B.

[0043] The lubricant content in the raw material powder, for example, is 0.025 to 0.2 mass percent. When the content is 0.025 mass percent or more, the lubricant can easily and widely disperse into the spaces between the plurality of particles under the processing heat in step B. Therefore, at least one of the holes and the groove can be easily formed in step C. When the above content is 0.2 mass percent or less, a dense green compact can be easily formed in step B. In addition, volume shrinkage due to loss of the lubricant during sintering of the workpiece in step D can be reduced, and a high-density sintered part with high dimensional accuracy can be easily manufactured. The content can be 0.04 to 0.18 mass percent. The content is a value at which the total amount of the raw material powder is set to 100 mass percent. [Step B: Creating a green body]

[0044] In step B, the raw material powder is pressed to produce a green compact with a relative density of 95% or more. The relative density can be 97% or more, especially 98% or more. The relative density of the green compact is determined as [(actual density of the green compact / true density of the green compact) × 100]. The meaning of the true density of the green compact is the same as the meaning of the actual density of the sintered compact (see above). The meaning of the actual density of the green compact is the same as the actual density of the sintered compact described above. The shape of the green compact is not particularly limited, and the shape can be appropriately selected. The shape of the green compact is, for example, columnar or tubular. The green compact is produced using a suitable die that can produce any of the above-mentioned shapes.

[0045] The molding pressure is adjusted so that the resulting green compact has a relative density of 95% or more and heat is generated to allow the lubricant to spread into the interstices between the particles. Specifically, in this step, the processing heat during molding allows the lubricant to spread. To allow the lubricant to spread, the mold is not heated by a heater. The molding pressure is, for example, 1560 MPa or more. The higher the molding pressure, the higher the relative density of the resulting green compact. The molding pressure can be 1660 MPa or more, 1760 MPa or more, especially 1860 MPa, and 1960 MPa or more. The upper limit of the molding pressure is not explicitly specified. [Step C: Creating the workpiece]

[0046] In step C, the green compact is subjected to at least one cutting process selected from hole drilling and grooving, thereby producing a workpiece having at least one hole or groove. The ratios between the diameter x1 and the depth y1 of the formed hole are within the ranges described above. The ratios between the width x2 and the depth y2 of the formed groove are within the ranges described above. Since the lubricant is distributed in the spaces between the particles of the green compact, at least one of a hole and a groove that meet the above-mentioned ranges can be formed. A drill is an example of a tool used to create the hole. Drilling can be performed under wet conditions with internal or external lubrication, depending on the diameter of the drill.Examples of tools used to create the groove are dicing blades, metal saws and grooving tools. [Step D: Sintering the workpiece]

[0047] In step D, the workpiece is sintered. Sintering the workpiece produces the sintered compact 1. As a result of sintering, the workpiece shrinks. The relative density of the workpiece corresponds to the relative density of the green compact. In particular, the workpiece has a high relative density. Therefore, the shrinkage of the workpiece due to sintering is very small. In this case, the relative density of the sintered compact 1 is greater than or equal to the relative density of the workpiece. In particular, the relative density of the sintered compact 1 is 95% or more. The dimensions of the hole and groove in the workpiece are maintained and are essentially the same as the dimensions of the hole 2 and the groove 3 in the sintered compact 1. The sintering conditions can be selected according to the composition of the raw material powder. The sintering temperature is, for example, 1100°C to 1400°C and can be 1200°C to 1300°C. The sintering time is, for example,15 minutes to 150 minutes and can be 20 minutes to 60 minutes. The usual sintering conditions can be used. [Next steps]

[0048] The method for producing a sintered molded article may further comprise at least one step selected from a step α in which the sintered molded article 1 is subjected to a heat treatment and a step β in which the sintered molded article 1 is subjected to a finishing process. (Step α: Heat treatment of the sintered part)

[0049] In step α, the sintered part 1 is subjected to carburizing and quenching, followed by tempering. The mechanical properties, particularly hardness and toughness, of the sintered part 1 are likely to be improved by step α. (Step β: Finishing of the sintered part)

[0050] In step β, the surface roughness of the sintered part 1 is reduced and the dimensions of the sintered part 1 are adjusted to its design dimensions. Examples of finishing include polishing the surface of the sintered part 1. <<Testbeispiel 1> >

[0051] In Test Example 1, sintered molded parts with holes were manufactured and the relationship between the diameter x1 and the depth y1 of the holes was evaluated. [Samples Nos. 1 to 7]

[0052] Sintered molding samples Nos. 1 to 7 were prepared by performing steps A to D of the above-described method for producing a sintered molding. [Step A]

[0053] In step A, a raw material powder containing a stainless steel powder and a lubricant was prepared. The composition of the stainless steel powder consisted of 16 mass percent Cr and 12 mass percent Ni, with the remainder being Fe and unavoidable impurities.

[0054] The lubricant was stearic acid. The melting point of stearic acid is 69.3°C. The lubricant content in the raw material powder was 0.1 mass percent. [Step B]

[0055] In step B, the raw material powder was pressed into green compacts. The pressing pressure was 1960 MPa.

[0056] The relative density of each green compact produced was 99.5%. The relative density of the green compact was determined as described above as [(actual density of the green compact) / (true density of the green compact) x 100]. [Step C]

[0057] In step C, the green compacts were drilled to produce workpieces with holes. The diameters x1 of the holes formed in samples Nos. 1 to 7 were 0.05 mm, 0.08 mm, 0.1 mm, 0.3 mm, 0.8 mm, 1.5 mm, and 2.0 mm, respectively.

[0058] Holes with different diameters x1 were created using drills with different diameters. Drilling was performed using the MQL (minimal quantity lubrication) method, in which the green compact was subjected to machining while a small amount of cutting fluid was supplied along with a large amount of compressed gas. When holes with a diameter of 0.05 mm, 0.08 mm, 0.1 mm, 0.3 mm, or 0.8 mm were created, the cutting fluid was supplied via external lubrication. When holes with a diameter of 1.5 mm or 2.0 mm were created, the cutting fluid was supplied via internal lubrication.

[0059] The machining conditions for the samples are shown in Table 1. The holes in the samples were drilled by step-feed drilling. The step drilling method is a drilling method in which the drill bit is repeatedly moved back and forth alternately to create a hole. The step size shown in Table 1 is the depth of the hole created by one feed motion of the drill bit. For example, if the step size in Table 1 is 2 mm, the operation is as follows. The drill bit is advanced to drill the green compact until the front end of the drill bit reaches a depth of 2 mm from the surface of the green compact. Then, the drill bit is retracted from the bottom of the drill hole until the front end of the drill bit reaches the surface of the green compact or a position behind the surface of the green compact. After that, the drill bit is advanced to drill the green compact until the front end of the drill bit reaches a depth of 2 mm from the bottom of the drill hole.The drill is then retracted from the bottom of the hole until the front end of the drill reaches the surface of the green compact or a position behind the surface of the green compact. The drill is repeatedly retracted and advanced alternately in the manner described above. The number of steps indicates how many times the drill is repeatedly advanced and retracted until it reaches the depth y1. If the step size is 2 mm and the depth y1 is 70 mm, the step number is a value obtained by dividing 70 by 2, i.e., 35. A value indicated in the "Relationship between diameter x1 and step width" column was obtained by dividing the diameter x1 by the step width. The value indicated in the "Relationship between diameter x1 and feed rate" column was obtained by dividing the feed rate by the diameter x1. [Table 1] Sample No. HOLE Number of revolutions Feed per revolution feed rate Step width Number of steps Relationship between diameter x1 and step width Relationship between diameter x1 and feed speed Diameter x1 Depth y1 y1 / x1 mm mm rpm mm mm / min mm Number of reps / min 1 0,05 0 8,0 15000 0,0008 12 0,01 40 5 240 2 0,08 0 10,0 12000 0,0008 9.6 0,01 80 8 120 3 0,1 3 33,0 12000 0,001 12 0,01 330 10 120 4 0,3 6 20,0 11000 0,002 22 0,03 200 10 73 5 0,8 15 18,8 7962 0,02 159 0,4 38 2 199 6 1,5 50 33,3 7430 0,05 372 1,5 34 1 248 7 2,0 70 35,0 7962 0,05 398 2 35 1 199

[0060] Fig. Figures 5 to 7 are graphs showing the relationship between the diameter x1 and the depth y1 of the holes in each of Samples Nos. 1 to 7. Fig. Figure 6 is an enlarged diagram of area A in Fig. 5. Fig. Figure 7 is an enlarged diagram of area B in Fig. 6. The horizontal axis of each of the diagrams in Fig. 5 to 7 represents the diameter x1 (mm) of the holes. The vertical axis of each of the diagrams in the Fig. 5 to 7 represents the depth y1 (mm) of the holes. In the diagrams in Fig. In Figures 5 to 7, the results for samples Nos. 1 to 7 are shown by circles.

[0061] In sample No. 1, holes with a diameter x1 of 0.05 mm and a depth y1 of 0.4 mm could be formed.

[0062] In sample No. 2, holes with a diameter x1 of 0.08 mm and a depth y1 of 0.8 mm could be formed.

[0063] In sample No. 3, holes with a diameter x1 of 0.1 mm and a depth y1 of 3.3 mm could be formed.

[0064] In sample No. 4, holes with a diameter x1 of 0.3 mm and a depth y1 of 6.0 mm could be formed.

[0065] In sample No. 5, holes with a diameter x1 of 0.8 mm and a depth y1 of 15.0 mm could be formed.

[0066] In sample No. 6, holes with a diameter x1 of 1.5 mm and a depth y1 of 50.0 mm could be formed.

[0067] In sample No. 7, holes with a diameter x1 of 2.0 mm and a depth y1 of 70.0 mm could be formed.

[0068] Twenty holes could be continuously formed in each sample. [Step D]

[0069] In step D, each of the workpieces with holes was heated to remove the lubricant, and the workpiece with the removed lubricant was sintered to produce a sintered element. The lubricant was removed from the workpiece by heating it to 100°C to 250°C. The workpiece without lubricant was held at 1100°C for 60 minutes. The sintering atmosphere was a vacuum.

[0070] The relative density of each sintered part produced was 96.2%. The relative density of the green compact was determined as described above as [(actual density of the sintered part) / (real density of the sintered part) x 100]. For all samples, the diameter x1 and depth y1 of the holes in the sintered part were essentially the same as the diameter x1 and depth y1 of the holes in the workpiece. (Samples Nos. 101 to 108)

[0071] Sintered molded part samples Nos. 101 to 107 were manufactured according to the same procedures as samples Nos. 1 to 7, except that the lubricant was not used in step A. Sintered molded part sample No. 108 was manufactured according to the same procedure as sample No. 107, except that the diameter x1 of the holes formed in step C was changed to 3.0 mm.

[0072] The diagrams in Fig. 5 to 7 also show the relationship between the diameter x1 and the depth y1 of the holes in each of the samples Nos. 101 to 108. In the diagrams in Fig. In Figures 5 to 7, the results for samples Nos. 101 to 108 are represented by triangles.

[0073] For sample No. 101, the diameter x1 of the holes was 0.05 mm and the depth y1 of the holes was limited to 0.35 mm.

[0074] For sample No. 102, the diameter x1 of the holes was 0.08 mm and the limit value for the depth y1 of the holes was 0.43 mm.

[0075] For sample No. 103, the diameter x1 of the holes was 0.1 mm and the depth y1 of the holes was limited to 1.0 mm.

[0076] For sample No. 104, the diameter x1 of the holes was 0.3 mm and the depth y1 of the holes was limited to 3.0 mm.

[0077] For sample No. 105, the diameter x1 of the holes was 0.8 mm and the limit of the depth y1 of the holes was 7.0 mm.

[0078] For sample No. 106, the diameter x1 of the holes was 1.5 mm and the depth y1 of the holes was limited to 30.0 mm.

[0079] For sample No. 107, the diameter x1 of the holes was 2.0 mm and the depth y1 of the holes was limited to 40.0 mm.

[0080] For sample No. 108, the diameter x1 of the holes was 3.0 mm and the depth y1 of the holes was limited to 50.0 mm.

[0081] The depth limit y1 is the depth limit of a hole with a diameter x1 that can be drilled without drill breakage. [Evaluation]

[0082] Among samples Nos. 1 to 7 and samples Nos. 101 to 107, samples with the same hole diameter x1 are compared. According to the illustration in the Fig. 5 to 7, the depths y1 in samples Nos. 1 to 7 are greater than the depths y1 in samples Nos. 101 to 107, regardless of the diameter x1.

[0083] The straight line L1 connecting the point of sample No. 101 and the point of sample No. 102 in Fig. 7, y1 = 2.67x1 + 0.217. The values ​​of the slope and intercept have been rounded.

[0084] The straight line L2, which connects the point for sample No. 102 and the point for sample No. 103 in Fig. 6, y1 = 28.5x1 - 1.85.

[0085] The straight line L3, which Fig. 6 shown point of sample No. 103 with the Fig. 5 of sample No. 104, y1 = 10x1.

[0086] The straight line L4 connecting the point of sample No. 104 and the point of sample No. 105 in Fig. 5, y1 = 8x1 + 0.6.

[0087] The straight line L5 connecting the point of sample No. 105 and the point of sample No. 106 in Fig. 5, y1 = 32.9x1 - 19.3. The values ​​of the slope and intercept have been rounded.

[0088] The straight line L6, which connects the point of sample No. 106 and the point of sample No. 107 in Fig. 5 has the form y1 = 20x1.

[0089] The straight line L7, which connects the point of sample No. 107 and the point of sample No. 108 in Fig. 5, y1 = 10x1 + 20.

[0090] As can be seen, the sintered parts with holes produced by using the powdered raw material containing the lubricant having a melting point of 150°C or less meet the following requirements (a1) to (a7). If 0.05≤x1<0.08, y1>2.67x1+0.217. If 0.08≤x1<0.1, y1>28.5x1−1.85. If 0.1≤x1<0.3, y1>10x1. If 0.3≤x1<0.8, y1>8x1+0.6. If 0.8≤x1<1.5, y1>32.9x1−19.3. If 1.5≤x1<2.0, y1>20x1. If 2,0≤x1, y1>10x1+20.

[0091] The straight line L8 connecting the point of sample No. 1 and the point of sample No. 2 in Fig. 7, y1 = 13.3x1 + 0.267. The values ​​of the slope and intercept have been rounded.

[0092] The straight line L9 connecting the point of sample No. 2 and the point of sample No. 3 in Fig. 6, y1 = 125x1 - 9.2. The values ​​of the slope and intercept have been rounded.

[0093] The straight line L10, which Fig. 6 shown point of sample No. 3 with the Fig. 5 to the point of sample No. 4, y1 = 13.5x1 + 1.95.

[0094] The straight line L11 connecting the point of sample No. 4 and the point of sample No. 5 in Fig. 5, y1 = 18x1 + 0.6.

[0095] The straight line L12 connecting the point of sample No. 5 and the point of sample No. 6 in Fig. 5, y1 = 50x1 - 25.

[0096] The straight line L13 connecting the point of sample No. 6 and the point of sample No. 7 in Fig. 5, y1 = 40x1 - 10.

[0097] The straight line L14, which passes through the Fig. 5 shown sample No. 7 and parallel to the straight line L7 is y1 = 10x1 + 50.

[0098] As can be seen, the hole-formed sintered molded articles produced by using the lubricant-containing raw material powder having a melting point of 150°C or below also satisfy the following requirements (a51) to (a56). If 0.05≤x1<0.08, y1=13.3x1+0.267. If 0.08≤x1<0.1, y1=125x1−9.2. If 0.1≤x1<0.3, y1=13.5x1+1.95. If 0.3≤x1<0.8, y1=18x1+0.6. If 0.8≤x1<1.5, y1=50x1−25. If 1.5≤x1<2.0, y1=40x1−10. If 2,0≤x1, y1=10x1+50. <<Testbeispiel 2> >

[0099] In Test Example 2, sintered molded parts with grooves were manufactured and the relationship between the width x2 and the depth y2 of the grooves was evaluated. [Samples Nos. 21 to 25]

[0100] Sintered compact samples Nos. 21 to 25 were prepared by the same procedure as sample No. 1, except that the green compact was grooved in step C to produce a grooved workpiece. [Step C]

[0101] The width x2 of the grooves formed in samples Nos. 21 to 25 was 0.05 mm, 0.1 mm, 0.2 mm, 0.3 mm, and 0.5 mm, respectively. The grooves with a width of 0.05 mm or 0.1 mm were created with a dicing blade. The grooves with a width of 0.2 mm, 0.3 mm, and 0.5 mm were formed with a metal saw.

[0102] Fig. 8 and Fig. 9 are diagrams showing the relationship between the width x2 and the depth y2 of the grooves in each of Sample Nos. 21 to 25. Fig. Figure 9 is an enlarged diagram of area C in Fig. 8. The horizontal axis of each of the diagrams in Fig. 8 and Fig. 9 represents the width x2 (mm) of the grooves. The vertical axis of each of the diagrams in the Fig. 8 and Fig. 9 represents the depth y2 (mm) of the grooves. In the diagrams in Fig. 8 and Fig. In Figure 9, the results for samples Nos. 21 to 25 are shown by circles.

[0103] In sample No. 21, grooves with a width x2 of 0.05 mm and a depth y2 of 0.7 mm could be formed.

[0104] In sample No. 22, grooves with a width x2 of 0.1 mm and a depth y2 of 1.0 mm could be formed.

[0105] In sample No. 23, grooves with a width x2 of 0.2 mm and a depth y2 of 1.6 mm could be formed.

[0106] In sample No. 24, grooves with a width x2 of 0.3 mm and a depth y2 of 9.0 mm could be formed.

[0107] In sample No. 25, grooves with a width x2 of 0.5 mm and a depth y2 of 19.0 mm could be formed. [Samples No. 201 to 207]

[0108] Sintered compacts Nos. 201 to 205 were manufactured using the same procedures as Samples Nos. 21 to 25, except that no lubricant was used in Step A. Sintered compacts Nos. 206 and 207 were manufactured using the same procedure as Sample No. 205, except that the width x2 of the groove formed in Step C was changed to 1.5 mm or 3.0 mm. The grooves with a width x2 of 1.5 mm and 3.0 mm, respectively, were machined using a keyway die.

[0109] The diagrams in the Fig. 8 and Fig. 9 show the relationship between the width x2 and the depth y2 of the grooves in each of the samples Nos. 201 to 207. In the diagrams in Fig. 8 and Fig. In Figure 9, the results for samples Nos. 201 to 207 are represented by triangles.

[0110] For sample No. 201, the width x2 of the grooves was 0.05 mm and the limit of the depth y2 of the grooves was 0.65 mm.

[0111] For sample No. 202, the width x2 of the grooves was 0.1 mm and the limit of the depth y2 of the grooves was 0.9 mm.

[0112] For sample No. 203, the width x2 of the grooves was 0.2 mm and the limit of the depth y2 of the grooves was 1.4 mm.

[0113] For sample No. 204, the width x2 of the grooves was 0.3 mm and the limit of the depth y2 of the grooves was 3.0 mm.

[0114] For sample No. 205, the width x2 of the grooves was 0.5 mm and the limit of the depth y2 of the grooves was 10.0 mm.

[0115] For sample No. 206, the width x2 of the grooves was 1.5 mm and the limit of the depth y2 of the grooves was 15.0 mm.

[0116] For sample No. 207, the width x2 of the grooves was 3.0 mm and the limit of the depth y2 of the grooves was 25.0 mm.

[0117] The limit of depth y2 is the limit of the depth of a groove with a width x2 that can be formed without tool breakage. [Evaluation]

[0118] Among samples Nos. 21 to 25 and Nos. 201 to 205, samples with the same groove width x2 are compared. As shown in the Fig. 8 and Fig. As shown in Figure 9, the depths y2 in Samples Nos. 21 to 25 are greater than the depths y2 in Samples Nos. 201 to 205, regardless of the width x2.

[0119] The straight line L21, which connects the point of sample No. 201 and the point of sample No. 203 in Fig. 9, y2 = 5x2 + 0.4.

[0120] The straight line L222, which Fig. 9 shown point of sample No. 203 with the Fig. The value of the slope and intercept connecting the point shown in Figure 8 of sample No. 205 is y2 = 28.7x2 - 4.3. The values ​​of the slope and intercept have been rounded.

[0121] The straight line L23, which connects the point of sample No. 205 and the point of sample No. 207 in Fig. 8, y2 = 6x2 + 7.

[0122] As can be seen, the sintered molded parts with grooves formed using the powdery raw material containing the lubricant having a melting point of 150°C or less meet the following requirements (b1) to (b3). If 0.05≤x2<0.2, y2>5x2+0.4. If 0.2≤x2<0.5, y2>28.7x2−4.3. If 0.5≤x2, y2>6x2+7.

[0123] The straight line L24, which connects the point of sample No. 21, the point of sample No. 22 and the point of sample No. 23 in Fig. 9, y2 = 6x2 + 0.4.

[0124] The straight line L25, which Fig. 9 shown point of sample No. 23 with the Fig. 8 to the point of sample No. 24, y2 = 74x2 - 13.2.

[0125] The straight line L26, which connects the point of sample No. 24 and the point of sample No. 25 in Fig. 8, y2 = 50x2 - 6.

[0126] The straight line L27, which passes through the Fig. 8 shown sample No. 23 runs parallel to the straight line L23 and y2 = 6x2 + 16.

[0127] As can be seen, the grooved sintered parts produced by using the lubricant-containing raw material powder having a melting point of 150°C or less satisfy the following requirements (b51) to (b54). If 0.05≤x2<0.2, y2=6x2+0.4. If 0.2≤x2<0.3, y2=74x2−13.2. If 0.3≤x2<0.5, y2=50x2−6. If 0.5≤x2, y2=6x2+16. <<Testbeispiel 3> >

[0128] In Test Example 3, the number of holes that can be made with a drill was evaluated. [Samples Nos. 31 to 34 and Samples Nos. 301 to 304]

[0129] Sintered compact samples Nos. 31 to 34 were manufactured according to the same procedure as Sample No. 1, except that the diameter of the holes formed in the green compact in step C was different from that of Sample No. 1. Sintered compact samples Nos. 301 to 304 were manufactured according to the same procedure as Sample Nos. 31 to 34, except that the lubricant was not used in step A. [Step C]

[0130] The diameters of the holes formed in samples Nos. 31 to 34 were 0.4 mm, 0.6 mm, 0.8 mm, and 1.0 mm, respectively. The diameters of the holes formed in samples Nos. 301 to 304 were 0.4 mm, 0.6 mm, 0.8 mm, and 1.0 mm, respectively. When the holes had a diameter of 0.4 mm or 0.6 mm, the cutting fluid was supplied by an external lubrication method. When the holes had a diameter of 0.8 mm or 1.0 mm, the cutting fluid was supplied by internal lubrication. The depth of the holes formed in the samples was the same. [Evaluation]

[0131] The number of holes that could be drilled with one drill was counted. When the number of holes reached 20, drilling was stopped. A number below 20 indicates the number of holes that could be drilled without breaking the drill.

[0132] In sample No. 31, 20 holes with a diameter of 0.4 mm could be formed.

[0133] In sample No. 32, 20 holes with a diameter of 0.6 mm could be formed.

[0134] In sample No. 33, 20 holes with a diameter of 0.8 mm could be formed.

[0135] For sample No. 34, the number of holes with a diameter of 1.0 mm that could be formed was 20.

[0136] For sample No. 301, the number of holes with a diameter of 0.4 mm that could be formed was 0.

[0137] For sample No. 302, the number of holes with a diameter of 0.6 mm that could be formed was 1.

[0138] In sample No. 303, 8 holes with a diameter of 0.8 mm could be formed.

[0139] In sample No. 304, 18 holes with a diameter of 1.0 mm could be formed.

[0140] For samples Nos. 31 to 34 and Nos. 301 to 304, samples with the same hole diameter are compared. As can be seen, the smaller the diameter of the holes formed, the greater the difference between the number of holes formed when the raw material powder contains the lubricant with a melting point of 150°C or less and the number of holes formed when the raw material powder does not contain the lubricant with a melting point above 150°C. <<Testbeispiel 4> >

[0141] In test example 4, drills with extra-long flutes were manufactured and the upper limit of the drilling depth was determined. [Samples Nos. 41 to 44]

[0142] The sintered molded part samples were prepared according to the same procedure as Sample No. 1, except that the processing conditions in step C were changed to those shown in Table 2. [Step C]

[0143] In sample No. 41, a drill with a flute length L of 30 mm, a diameter D of 0.6 mm, and an L / D of 50 was used to form holes. In sample No. 42, a drill with a flute length L of 40 mm, a diameter D of 0.8 mm, and an L / D of 50 was used to form holes. In sample No. 43, a drill with a flute length L of 40 mm, a diameter D of 1.0 mm, and an L / D of 40 was used to form holes. In sample No. 44, a drill with a flute length L of 50 mm, a diameter D of 1.0 mm, and an L / D of 50 was used to form holes. In the diagram in Fig. In Figure 5, the results for samples Nos. 41 to 44 are shown by circles. [Table 2] Sample No. Hole Number of revolutions Feed per revolution feed rate Step width Number of levels Relationship between diameter x1 and step width Relationship between diameter x1 and feed rate Diameter x1 Depth y1 y1 / x1 mm mm rpm mm mm / min mm Number of reps / min 41 0,6 30 50 9290 0,005 46 0,06 500 10 77 42 0,8 40 50 8276 0,02 166 0,3 134 3 207 43 1,0 40 40 6370 0,025 159 1 40 1 159 44 1,0 50 50 6370 0,03 191 1 50 1 191 [Evaluation]

[0144] In each sample, 320 holes could be continuously drilled using a single drill. No drill breakage or other machining problems occurred during hole formation. From these results, it can be deduced that the upper limit of the depth y1 of holes is determined by a limitation on the availability of a drill suitable as a tool. It was found that holes with y1 / x1 ≥ 50 can be achieved, at least within the range shown. From the above results, it can be seen that a hole with y1 / x1 = 60, y1 / x1 = 80, and especially with y1 / x1 = 100 could be produced if a suitable drill were available.

[0145] The straight line L40, which connects the point for sample No. 41, the point for sample No. 42 and the point for sample No. 44 in Fig. 5, y1 = 50x1. The following values ​​are obtained by combining the results in Test Example 1 and the results in Test Example 4, with the upper limit set to y1 / x1 = 50. If 0.1≤x1<0.3, 50x1≥y1>10x1. If 0.3≤x1<0.8, 50x1≥y1>8x1+0.6. If 0.8≤x1<1.5, 50x1≥y1>32.9x1−19.3. If 1.5≤x1<2.0, 50x1≥y1>20x1.

[0146] The following results are obtained by combining the results of Test Example 1 and Test Example 4, with the upper limit set to y1 / x1 = 80. If 0.1≤x1<0.3, 80x1≥y1>10x1. If 0.3≤x1<0.8, 80x1≥y1>8x1+0.6. If 0.8≤x1<1.5, 80x1≥y1>32.9x1−19.3. If 1.5≤x1<2.0, 80x1≥y1>20x1.

[0147] The results of test examples 1 and 4 show the following.

[0148] A hole with a large depth y1 relative to the diameter x1 can be easily made by step drilling.

[0149] The upper limit for the number of steps is not particularly restricted, and the number of steps can be set reasonably as long as the processing time is not excessively long.

[0150] It is desirable that the step width be smaller the smaller the diameter x1. For example, the step width is less than or equal to the diameter x1. The step width can be less than or equal to 1 / 2 of the diameter x or less than or equal to 1 / 5 of the diameter x1.

[0151] It is desirable that the feed rate is less than or equal to 250 times the diameter x1.

[0152] The present invention is not limited to the above examples and is defined by the scope of the claims. It is intended that the present invention encompass all modifications that fall within the scope and meaning of the claims.

[0153] In connection with the above-described embodiments of the present invention, the following appendix is ​​further disclosed. [Appendix 1]

[0154] A sintered compact formed from a metal, the sintered compact having a relative density of 95% or more, and the sintered compact having a hole with a diameter x1 (mm) and a depth y1 (mm), the diameter x1 and the depth y1 meeting the following requirements (α1) to (α4): if 0.1≤x1<0.3, 50x1≥y1≥10x1+2; if 0.3≤x1<0.8, 50x1≥y1≥20x1−1; if 0.8≤x1<1.5, 50x1≥y1≥50x1−25; and if 1.5≤x1<2.0, 50x1≥y1≥40x1−10.

[0155] The sintered part in Appendix 1 has a hole with a large depth relative to its diameter. LIST OF REFERENCE SYMBOLS 1 sintered molded part 2 holes 3 grooves x1 diameter y1 depth x2 width y2 depth A, B, C area L1, L2, L3, L4, L5, L6, L7 Straight L8, L9, L10, L11, L12, L13, L14 Straight L21, L22, L23 Straight L24, L25, L26, L27 Straight QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2022-071901

[0002] JP 2019-14971

[0004] < / details>

Claims

[1] Sintered molded part formed from a metal, wherein the sintered molded article has a relative density of 95% or more, wherein the sintered molded part has a hole with a diameter x1 (mm) and a depth y1 (mm) and / or a groove with a width x2 (mm) and a depth y2 (mm), wherein the diameter x1 and the depth y1 satisfy the following requirements (a1) to (a7), wherein the width x2 and the depth y2 satisfy the following requirements (b1) to (b3): if 0.05≤x1<0.08, y1>2.67x1+0.217; if 0.08≤x1<0.1, y1>28.5x1−1.85; if 0.1≤x1<0.3, y1>10x1; if 0.3≤x1<0.8, y1>8x1+0.6; if 0.8≤x1<1.5, y1>32.9x1−19.3; if 1.5≤x1<2.0, y1>20x1; if 2,0≤x1, y1>10x1+20; if 0.05≤x2<0.2, y2>5x2+0.4; if 0.2≤x2<0.5, y2>28.7x2−4.3; and if 0.5≤x2, y2>6x2+7. [2] A sintered molded article according to claim 1, wherein the metal is pure iron or an iron alloy. [3] The sintered molded article according to claim 1, wherein the metal is stainless steel. [4] A method for producing a sintered molded part, the method comprising: preparing a raw material powder comprising a metal powder and a lubricant; pressing the raw material powder to produce a green compact with a relative density of 95% or more; subjecting the green compact to at least one cutting process selected from hole drilling and grooving to produce a workpiece having a hole with a diameter x1 (mm) and a depth y1 (mm) and / or a groove with a width x2 (mm) and a depth y2 (mm), wherein the diameter x1 and the depth y1 satisfy the following requirements (a1) to (a7), wherein the width x2 and the depth y2 satisfy the following requirements (b1) to (b3); and sintering of the workpiece, wherein the proportion of lubricant contained in the raw material powder is 0.025 mass percent to 0.2 mass percent, and wherein the lubricant has a melting point of 150°C or less: if 0.05≤x1<0.08, y1>2.67x1+0.217; if 0.08≤x1<0.1, y1>28.5x1−1.85; if 0.1≤x1<0.3, y1>10x1; if 0.3≤x1<0.8, y1>8x1+0.6; if 0.8≤x1<1.5, y1>32.9x1−19.3; if 1.5≤x1<2.0, y1>20x1; if 2,0≤x1, y1>10x1+20; if 0.05≤x1<0.2, y2>5x2+0.4; if 0.2≤x2<0.5, y2>28.7x2−4.3; and if 0.5≤x2, y2>6x2+7. [5] A method for producing a sintered molded article according to claim 4, wherein the lubricant is stearic acid, erucic acid amide or stearic acid amide.

Images