Sintered body and method for manufacturing a sintered body

Abstract

To provide a sintered compact in which a through hole is formed at the bottom of a recessed part and having a simplifiable production process.SOLUTION: Provided is a sintered compact formed of metal powders, in which a recessed part is formed at either face in a thickness direction and a through hole which passes through in the thickness direction is formed at the bottom face of the recessed part, and a hole wall face is tilted with respect to the thickness direction in such a manner that a hole area is progressively reduced from either side to the other side of the thickness direction in at least a part of a circumferential direction of the through hole.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] As a method for manufacturing a sintered body, a method (powder metallurgy) of filling a mold with a raw metal powder, heat-treating the formed body thus produced, and sintering the metal powder is known. Powder metallurgy is suitable for mass-producing products of the same shape and is adopted as a method for manufacturing sintered bodies of various shapes and materials. For example, Patent Document 1 describes manufacturing a sintered component by heat-treating a formed body obtained by molding an alloy powder composition containing an alloy powder made of austenitic stainless steel.

[0003] Further, Patent Document 2 describes manufacturing a sintered soft magnetic member by compacting an Fe alloy powder containing silicon and iron elements into a desired shape and sintering the obtained formed body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, when forming a molded body with a through-hole at the bottom of a recess using a multi-stage press, excessive load is placed on the punch due to friction between the punch and the through-hole when the punch is withdrawn from the through-hole. Furthermore, there is a problem that the area around the through-hole of the molded body is prone to damage due to friction. For this reason, molded bodies without a through-hole at the bottom of the recess are formed using a multi-stage press, and after sintering, the through-hole is machined into the bottom of the recess of the sintered body. Thus, in order to manufacture a sintered body with a through-hole at the bottom of the recess, it is necessary to sinter the molded body with the recess and then post-process the through-hole into the bottom of the recess, which complicates the manufacturing process of the sintered body.

[0006] In view of the above circumstances, this disclosure aims to provide a sintered body having a through hole formed at the bottom of a recess, a sintered body that can simplify the manufacturing process, and a method for manufacturing the sintered body. [Means for solving the problem]

[0007] The following embodiments are included as means for solving the above problems. <1> A sintered body formed from metal powder, A recess is formed on one side in the thickness direction. A through hole is formed in the bottom surface of the recess, penetrating in the thickness direction. A sintered body in which, in at least a portion of the circumferential direction of the through hole, the hole wall surface is inclined with respect to the thickness direction such that the hole area gradually decreases from one side to the other in the thickness direction. <2> In at least a portion of the through hole in the circumferential direction, the hole wall surface is inclined within a range of 5 to 20 degrees with respect to the thickness direction. <1> The sintered body described above. <3> A portion of the circumferential wall surface of the through hole and a portion of the circumferential wall surface of the recess are continuous in the thickness direction. <1> or <2> The sintered body described above. <4> <1> ~ <3> A method for manufacturing a sintered body according to any one of the following items: A process of filling a mold with metal powder and applying pressure to form a molded body, The process of sintering the molded body, It has, A method for manufacturing a sintered body, wherein the projection of the mold that forms the through hole in the molded body, which becomes the through hole in the sintered body, has a side wall surface of the projection that is inclined with respect to the opening and closing direction of the mold, such that the cross-sectional area of ​​the projection gradually decreases from the root side to the tip side in at least a portion of the circumferential direction of the projection. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a sintered body in which a through hole is formed at the bottom of a recess, a sintered body that can simplify the manufacturing process, and a method for manufacturing the sintered body. [Brief explanation of the drawing]

[0009] [Figure 1] This is a front view of a sintered body according to one embodiment of the present disclosure. [Figure 2] This is a rear view of a sintered body in one embodiment of the present disclosure. [Figure 3] This is a 3X-3X cross-sectional view of Figure 1. [Figure 4] This is a cross-sectional view of a mold (corresponding to Figure 3) showing the state in which metal powder has been filled into the mold in a method for manufacturing a sintered body according to one embodiment of the present disclosure. [Figure 5] This is a cross-sectional view of the mold (corresponding to Figure 4) showing the state in which the metal powder inside the mold is being pressed by the upper and lower punches, as shown in Figure 4. [Figure 6] This is a cross-sectional view of the mold (corresponding to Figure 5) showing the process of demolding a molded body that has been pressure-molded using the mold shown in Figure 5. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments for implementing the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless specifically stated. The same applies to numerical values and their ranges, which do not limit the present disclosure.

[0011] In the present disclosure, the term "process" includes, in addition to a process independent of other processes, the process even if it cannot be clearly distinguished from other processes as long as the purpose of the process is achieved.

[0012] In the numerical range indicated by "~" in the present disclosure, the numerical values described before and after "~" are included as the minimum value and the maximum value, respectively. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0013] First, the sintered body of the present embodiment will be described. Next, the manufacturing apparatus and the manufacturing method for manufacturing the sintered body of the present embodiment will be described.

[0014] <Sintered Body> The sintered body of the present embodiment is a sintered body formed of metal powder, in which a concave portion is formed on one surface in the thickness direction, a through hole penetrating in the thickness direction is formed on the bottom surface of the concave portion, and in at least a part of the circumferential direction of the through hole, the hole wall surface is inclined with respect to the thickness direction so that the hole area gradually decreases from one side to the other side in the thickness direction. Hereinafter, specific examples of the sintered body will be described with reference to the drawings, but the present disclosure is not limited thereto.

[0015] The sintered body 20 of this embodiment is used as an automobile part. Specifically, as shown in Figures 1 to 3, it is used as a yoke for an electromagnetic clutch. However, the applications of the sintered body of this disclosure are not limited to automobile parts.

[0016] The sintered body 20 is formed from metal powder. Examples of this metal powder include powder containing silicon and iron. Furthermore, the powder containing silicon and iron is not particularly limited and may include, for example, Fe alloy powder containing silicon and iron, or a mixed powder of Si powder containing silicon and Fe powder containing at least iron.

[0017] As shown in Figures 1 to 3, the sintered body 20 comprises a main body portion 22, a recess 24, and a through hole 26.

[0018] As shown in Figure 1, the main body portion 22 is formed in a disc shape. A through hole 23 is formed in the radial center of the main body portion 22, penetrating in the thickness direction of the main body portion 22. In the following description, the radial direction of the main body portion 22 is indicated by arrow R, and the thickness direction of the main body portion 22 is indicated by arrow T. A recess 24 is formed on one surface 22A in the thickness direction of the main body portion 22.

[0019] As shown in Figures 1 and 2, the recess 24 is formed on one surface 22A of the main body 22. This recess 24 is a recessed portion that is recessed toward the other side in the thickness direction of the main body 22, and is formed in an annular shape on one surface 22A with the hole center C of the through hole 23 of the main body 22 as the center. For example, an electromagnetic clutch coil is housed in this recess 24. In addition, as shown in Figure 3, the recess 24 of this embodiment has opposing recessed wall surfaces 24A and 24B that extend along the thickness direction of the main body 22. In this embodiment, recessed wall surface 24A refers to the wall surface located radially inward of the recess 24, and recessed wall surface 24B refers to the wall surface located radially outward of the recess 24. The bottom surface 24C of the recess 24 extends along a direction perpendicular to the thickness direction of the main body 22 (the same direction as the radial direction). A through hole 26 is formed in the bottom surface 24C of the recess 24, which penetrates the bottom of the recess 24 in the thickness direction of the main body 22.

[0020] As shown in Figure 3, the through hole 26 extends from the bottom surface 24C of the recess 24 toward the other surface 22B in the thickness direction of the main body 22, and penetrates the bottom of the recess 24. Here, the bottom of the recess 24 refers to the portion of the main body 22 from the bottom surface 24C of the recess 24 toward the other surface 22B of the main body 22.

[0021] As shown in Figures 1 and 2, the through-hole 26 is oval-shaped when viewed from the thickness direction of the main body 22. As shown in Figure 1, the hole wall surface 26A of the through-hole 26 is inclined with respect to the thickness direction of the main body 22 in at least a portion of the circumferential direction of the through-hole 26 such that the hole area gradually decreases from one side (side 22A) to the other side (side 22B) in the thickness direction (see Figure 3). Specifically, an inclined portion 27 is formed on the hole wall surface 26A in a portion of the circumferential direction of the through-hole 26, in which the hole area gradually decreases from one side to the other in the thickness direction. In this embodiment, the inclined portion 27 is formed on the hole wall surface 26A of the through-hole 26 located radially outward from the main body 22, and the hole wall surface 26A of the other portion of the through-hole 26 (the portion where the inclined portion 27 is not formed) extends along the thickness direction of the main body 22.

[0022] As shown in Figure 3, the inclined portion 27 of the hole wall surface 26A is inclined at an angle θ with respect to the thickness direction of the main body portion 22. This angle θ is preferably set within the range of 5 to 20 degrees, more preferably 8 to 15 degrees.

[0023] Furthermore, the length of the inclined portion 27 of the hole wall surface 26A along the thickness direction of the main body portion 22 is preferably set within the range of 80% to 100%, more preferably 90% to 100%, of the length L of the through hole 26 along the thickness direction of the main body portion 22, as shown in Figure 3.

[0024] In this embodiment, a portion of the circumferential wall surface 26A of the through hole 26 and a portion of the circumferential wall surface 24B of the recess 24 are continuous in the thickness direction of the main body 22. Specifically, as shown in Figures 1 and 3, the portion of the hole wall surface 26A of the through hole 26 that is opposite to the portion where the inclined portion 27 is formed is continuous with a portion of the recess surface 24B of the recess 24.

[0025] Furthermore, as shown in Figure 2, the sintered body 20 of this embodiment has a groove 30 formed on the other surface 22B of the main body 22, extending from the through hole 26 to the outer peripheral edge of the main body 22. This groove 30 is, for example, a groove for passing wiring extending from a coil housed in the recess 24. The wiring of the coil extends to the outside of the sintered body 20 through the through hole 26 and the groove 30.

[0026] <Manufacturing equipment for sintered body 20> Next, a multi-stage press machine 50, which is used to form a molded body 40 from metal powder, will be described using Figures 4 to 6 as part of the manufacturing apparatus for producing the sintered body 20 of this embodiment.

[0027] As shown in Figures 4 to 6, the multi-stage press machine 50 is equipped with a mold 52 for forming metal powder. This mold 52 comprises a core 54, a die 56, an upper punch 58, a lower punch 60, a lower punch 62, and a lower punch 64.

[0028] The core 54 is a mold member that forms the through-holes 23 of the molded body 40, which correspond to the through-holes 23 of the sintered body 20. The die 56 is a mold member that forms the outer circumferential surface of the main body portion 42 of the molded body 40, which corresponds to the outer circumferential surface of the main body portion 22 of the sintered body 20.

[0029] Furthermore, the upper punch 58 is a mold member that forms the other surface 42B of the main body portion 42 of the molded body 40, which corresponds to the other surface 22B of the main body portion 22 of the sintered body 20.

[0030] The lower punches 60 and 64 are mold members that form one surface 42A of the main body portion 42 of the molded body 40, which corresponds to one surface 22A of the main body portion 22 of the sintered body 20.

[0031] Furthermore, the lower punch 62 is a mold member that forms a recess 44 in the molded body 40 that corresponds to a recess 24 in the sintered body 20. The lower punch 62 also has a projection 63 formed on it for forming a through hole 46 in the molded body 40 that corresponds to a through hole 26 in the sintered body 20. At least a portion of the circumferential direction of this projection 63 is inclined with respect to the pressing direction of the mold 52 (a direction parallel to the thickness direction of the molded body 40) such that the cross-sectional area of ​​the projection 63 gradually decreases from the root side to the tip side. Specifically, an inclined portion 63B is formed on the side wall surface 63A of the projection 63 in the portion corresponding to the inclined portion 47 of the hole wall surface 46A of the through hole 46 in the molded body 40.

[0032] Furthermore, the multi-stage press machine 50 is equipped with a drive source (not shown) for pressurizing (pressing) the metal powder using the upper punch 58 and the lower punches 60-64.

[0033] <Method for manufacturing sintered bodies> Next, a method for manufacturing the sintered body according to this embodiment will be described. The manufacturing method for a sintered body of this embodiment is a method for manufacturing a sintered body in which a recess is formed on one surface in the thickness direction, a through hole is formed in the bottom surface of the recess and penetrates in the thickness direction, and in at least a portion of the circumferential direction of the through hole, the hole wall surface is inclined with respect to the thickness direction such that the hole area gradually decreases from one side to the other in the thickness direction, comprising the steps of filling a mold with metal powder and pressurizing to form a molded body, and sintering the molded body, wherein the projection of the mold that forms the through hole of the molded body which becomes the through hole of the sintered body has a side wall surface inclined with respect to the opening and closing direction of the mold in at least a portion of the circumferential direction of the projection such that the cross-sectional area of ​​the projection gradually decreases from the root side to the tip side.Specific examples of the manufacturing method for a sintered body will be described below with reference to the drawings, but this disclosure is not limited thereto.

[0034] First, various powders are mixed to produce metal powder.

[0035] Next, metal powder is filled into the mold 52 of the multi-stage press machine 50 shown in Figure 4. Then, as shown in Figure 5, the filled metal powder is pressed by the upper and lower punches to form the molded body 40.

[0036] Then, as shown in Figure 5, the molded body 40 is demolded from the mold 52. In this embodiment, since an inclined portion 47 is formed on a part of the hole wall surface 46A of the through hole 46 of the molded body 40, for example, compared to a configuration in which the through hole 46 is of a constant diameter, friction between the projection 63 and the hole wall surface 46A is reduced when the projection 63 of the lower punch 62 is pulled out of the through hole 46. By reducing the friction between the projection 63 and the hole wall surface 46A in this way, the load on the projection 63 when the lower punch 62 is pulled out is reduced. Furthermore, damage to the surrounding parts of the through hole 46 of the molded body 40 (hole wall surface 46A, hole edge, etc.) is also suppressed.

[0037] Next, the molded body 40 is sintered to form the sintered body 20. Then, the angular parts of the sintered body 20 (for example, the outer edge or the edge of the hole) are chamfered with C-chamfers or R-chamfers to give the sintered body 20 the shape of the product.

[0038] Next, the operation and effects of this embodiment will be described. In the sintered body 20 of this embodiment, in a portion of the circumferential direction of the through hole 26 formed in the bottom surface 24C of the recess 24, the hole wall surface 26A is inclined with respect to the thickness direction of the main body 22 such that the hole area gradually decreases from one side to the other in the thickness direction of the main body 22. That is, an inclined portion 27 is formed in the through hole 26. In a molded body 40 which becomes such a sintered body 20, the portion corresponding to the inclined hole wall surface 26A (inclined portion 27) of the through hole 26 (inclined portion 47 of the through hole 46) is inclined, so as shown in Figure 6, the load on the mold 52 can be reduced when demolding the molded body 40, and furthermore, damage to the peripheral portion of the through hole 46 of the molded body 40 can be suppressed. Thus, in the sintered body 20 of this embodiment, by forming an inclined portion 27 in the through hole 26, even if the through hole 46 is formed in the bottom surface 44C of the recess 44 during molding of the molded body 40, defects are less likely to occur in the mold 52 and the molded body 40, and therefore there is no need to post-process the bottom surface of the recess into a through hole after sintering. For this reason, the manufacturing process of the sintered body 20 can be simplified compared to, for example, the case where a through hole is post-processed into the bottom surface of the recess of the sintered body after sintering the molded body.

[0039] Furthermore, in the sintered body 20, the angle θ of the inclined portion 27 is set within the range of 5 to 20 degrees. Here, if the angle θ is less than 5 degrees, the effect of reducing friction between the inclined portion 47 of the molded body 40 corresponding to the inclined portion 27 and the projection 63 of the lower punch 62 is small. Also, if the angle θ exceeds 20 degrees, the projection 63 that forms the through hole 46 of the molded body 40 becomes smaller in diameter, and the strength of the projection 63 decreases, making it more prone to defects. For this reason, it is preferable to set the angle θ of the inclined portion 27 of the sintered body 20 within the range of 5 to 20 degrees, more preferably within the range of 8 to 15 degrees.

[0040] Furthermore, in the sintered body 20, the length of the inclined portion 27 of the hole wall surface 26A along the thickness direction of the main body portion 22 is set to be within the range of 80% to 100% of the length L of the through hole 26. Here, if the length of the inclined portion 27 is less than 80%, the effect of reducing friction between the inclined portion 47 of the molded body 40 corresponding to the inclined portion 27 and the projection 63 of the lower punch 62 is reduced. For this reason, it is preferable to set the length of the inclined portion 27 of the sintered body 20 to be within the range of 80% to 100%, more preferably 90% to 100%, of the length L of the through hole 26.

[0041] Furthermore, in the sintered body 20, a portion of the circumferential hole wall surface 26A of the through hole 26 and a portion of the circumferential recessed wall surface 24B of the recess 24 are continuous in the thickness direction of the main body 22. Therefore, compared to, for example, a case where there is an inflection point between the hole wall surface 26A and the recessed wall surface 24B, the thickness of the projection 63 that forms the through hole 46 of the corresponding molded body 40 can be ensured. This ensures the strength of the mold 52 (the projection 63 of the lower punch 62).

[0042] [Other embodiments] In the above-described embodiment, a portion of the circumferential hole wall surface 26A of the through hole 26 of the sintered body 20 is inclined with respect to the thickness direction of the main body 22. However, the present disclosure is not limited to this configuration, and the entire circumferential hole wall surface 26A of the through hole 26 of the sintered body 20 may be inclined with respect to the thickness direction of the main body 22.

[0043] Furthermore, in the above-described embodiment, as shown in Figure 1, the through-hole 26 of the sintered body 20 is formed closer to the concave wall surface 24A in the width direction of the recess 24, but the present disclosure is not limited to this configuration. For example, the through-hole 26 of the sintered body 20 may be formed closer to the concave wall surface 24B in the width direction of the recess 24, or the through-hole 26 may be formed so that its center coincides with the center of the recess 24 in the width direction.

[0044] While preferred embodiments of this disclosure have been described above, this disclosure is not necessarily limited to the embodiments described above, and modifications may be made as appropriate without departing from its spirit. [Explanation of Symbols]

[0045] 20 Sintered body 22A One side 22B The other side 24 recesses 24B Concave wall surface 24C Bottom 26 Through holes 26A hole wall surface 40 molded body 44 recess 44C Bottom 46 Through hole 52 molds 63 Protrusion 63A Side wall θ angle T thickness direction

Claims

1. A sintered body formed from metal powder, It has a disc-shaped main body, The main body portion has one surface and the other surface facing each other in the thickness direction, A recess is formed on one of the aforementioned surfaces, A through hole is formed in the bottom surface of the recess, penetrating through the main body in the thickness direction. A sintered body in which, in at least a portion of the circumferential direction of the through hole, the hole wall surface is inclined with respect to the thickness direction of the main body such that the hole area gradually decreases from one side to the other in the thickness direction of the main body.

2. The sintered body according to claim 1, wherein in at least a portion of the circumferential direction of the through hole, the hole wall surface is inclined within a range of 5 to 20 degrees with respect to the thickness direction of the main body.

3. The sintered body according to claim 1, wherein a portion of the circumferential wall surface of the through hole and a portion of the circumferential wall surface of the recess are continuous in the thickness direction of the main body.

4. A method for manufacturing a sintered body according to any one of claims 1 to 3, A process of filling a mold with metal powder and applying pressure to form a molded body, The process of sintering the molded body, It has, A method for manufacturing a sintered body, wherein the projection of the mold that forms the through hole in the molded body, which becomes the through hole in the sintered body, has a side wall surface of the projection that is inclined with respect to the opening and closing direction of the mold, such that the cross-sectional area of ​​the projection gradually decreases from the root side to the tip side in at least a portion of the circumferential direction of the projection.

Images