Device for producing powder molded article and method for producing powder molded article

Abstract

Provided is a device that is for producing a powder molded article and that comprises: a die which has a hollow part that passes therethrough in a first direction; a first core which is inserted in the hollow part along the first direction; an upper punch and lower punch which compress a powder disposed inside the hollow part; and a drive mechanism which moves the first core in the first direction. The first core is provided with a protrusion that protrudes from a side surface of the first core in a direction intersecting the first direction. The drive mechanism is provided with a cylinder that imparts a motive power to the first core in a manner causing movement thereof independently of the die, the upper punch, and the lower punch.

Description

Apparatus for manufacturing powder compact and method for manufacturing powder compact

[0001] The present disclosure relates to a powder compact manufacturing apparatus and a powder compact manufacturing method. This application claims priority to Japanese Patent Application No. 2024-110531 filed on July 9, 2024, the entire contents of which are incorporated by reference.

[0002] Patent Document 1 discloses a mold for producing a compact having an undercut shape. The mold includes a first die, a second die, a first punch, and a second punch. The first punch is an upper punch, and the second punch is a lower punch. The second die has an undercut forming portion that imparts the undercut shape to the compact. The undercut forming portion includes, for example, a protrusion. The second die is inserted into the through hole of the first die from below so that the outer surface of the second die contacts the inner surface of the through hole. A compact is produced by compressing powder filled in a cavity formed by the inner surface of the through hole of the first die, the second die, and the second punch with the first punch and the second punch. When compressing the powder, the lower end surface of the first punch and the upper end surface of the second die engage with each other.

[0003] Japanese Patent Application Laid-Open No. 2021-000664

[0004] The presently disclosed apparatus for manufacturing a powder compact includes a die having a hollow portion penetrating in a first direction, a first core inserted into the hollow portion along the first direction, an upper punch and a lower punch for compressing powder disposed in the hollow portion, and a drive mechanism for moving the first core along the first direction. The first core includes a protrusion protruding from a side surface of the first core in a direction intersecting the first direction. The drive mechanism includes a cylinder for applying power to the first core so that the first core moves independently of the die, the upper punch, and the lower punch.

[0005] FIG. 1 is a longitudinal cross-sectional view of the powder molding manufacturing apparatus according to the embodiment, showing a state in which the upper punch, lower punch, first core, and second core are not inserted into the die. FIG. 2 is a longitudinal cross-sectional view of the powder molding manufacturing apparatus according to the embodiment, showing a state in which the lower punch, first core, and second core are inserted into the die, but the upper punch is not inserted into the die. FIG. 3 is a longitudinal cross-sectional view of the powder molding manufacturing apparatus according to the embodiment, showing a state in which the upper punch is being lowered from the state shown in FIG. 2. FIG. 4 is a longitudinal cross-sectional view of the powder molding manufacturing apparatus according to the embodiment, showing a state in which the upper punch is further lowered from the state shown in FIG. 3 to compress the powder between the upper punch and the lower punch, and the first core is moved to a predetermined position. FIG. 5 is a transverse cross-sectional view of the powder molding manufacturing apparatus shown in FIG. 4. FIG. 6 is a longitudinal cross-sectional view of the powder molding manufacturing apparatus according to the embodiment, showing a state in which a manufactured powder molding is being removed. FIG. 7 is a perspective view of a powder molding formed using the powder molding manufacturing apparatus according to the embodiment.

[0006] [Problem to be Solved by the Present Disclosure] If the size of the undercut molding portion, for example, the protrusion length, is large, resistance force from the powder acts below the protrusion when compressing the powder, which may prevent the second die from being pressed down to the appropriate position. If the second die is not in the appropriate position, the undercut portion in the manufactured powder compact will not be positioned as expected. Furthermore, if the second die is not in the appropriate position, the powder may not be compressed sufficiently. If the lower end surface of the first punch and the upper end surface of the second die are engaged with each other, as in the mold disclosed in Patent Document 1, the second die is forcibly pressed down even if resistance force from the powder acts below the protrusion. However, if the lower end surface of the first punch and the upper end surface of the second die are engaged with each other, the first punch and the second die move simultaneously, making it impossible to individually adjust the timing of moving the first punch and the timing of pressing down the second die. If the first punch and the second die move simultaneously, depending on the shape and size of the protrusion, the powder may not be compressed sufficiently.

[0007] An object of the present disclosure is to provide a powder compact manufacturing apparatus that can manufacture powder compacts having undercut shapes with high precision and efficiency.

[0008] Effect of the Present Disclosure The powder compact manufacturing apparatus of the present disclosure can manufacture powder compacts having undercut shapes with high precision and efficiency.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described.

[0010] (1) An apparatus for manufacturing a powder compact according to an embodiment of the present disclosure includes a die having a hollow portion penetrating in a first direction, a first core inserted into the hollow portion along the first direction, an upper punch and a lower punch for compressing powder disposed in the hollow portion, and a drive mechanism for moving the first core along the first direction. The first core includes a protrusion protruding from a side surface of the first core in a direction intersecting the first direction. The drive mechanism includes a cylinder for applying power to the first core so that the first core moves independently of the die, the upper punch, and the lower punch.

[0011] The first direction is the direction in which the upper punch and the lower punch move relative to the die, and is the direction in which the powder is compressed. Although the first core is referred to as a core in this disclosure, depending on the configuration of the powder compact manufacturing apparatus, it may be a component generally referred to as a punch. The first core may be called any component as long as it has a protrusion protruding from its side surface in a direction intersecting the first direction and serves to impart an undercut shape to the powder compact to be manufactured.

[0012] In the powder compact manufacturing apparatus of the present disclosure, the first core can be moved along a first direction by a drive mechanism. Therefore, even if resistance force from the powder is applied below the protrusion when compressing the powder, the first core can be forcibly moved downward. By moving the first core, the protrusion is positioned appropriately when compressing the powder. Therefore, in the manufactured powder compact, the undercut portion is positioned at a predetermined position with high precision. In the powder compact manufacturing apparatus of the present disclosure, the timing of moving the first core and the timing of moving components other than the first core can be independently adjusted. If the timing of moving the first core can be independently adjusted, powder can be appropriately compressed regardless of the shape and size of the protrusion of the first core.

[0013] (2) In the powder molding manufacturing apparatus of (1) above, the first core may be inserted into the hollow portion from the same direction as the lower punch, the drive mechanism may include a lower plate connected to the lower end of the first core, and the cylinder may move the lower plate along the first direction.

[0014] The first core is interlocked with the lower plate, making it easier to forcibly move the first core downward.

[0015] (3) In the powder molding manufacturing apparatus of (2) above, the upper end of the cylinder may be supported by an upper plate connected to the upper end of the upper punch, and the lower end of the cylinder may be freely in contact with the lower plate.

[0016] By disposing the cylinder between the upper plate and the lower plate, the powder compact manufacturing device can be made smaller.

[0017] (4) In the powder molding manufacturing apparatus according to any one of (1) to (3) above, the upper end surface of the first core may be out of contact with the lower end surface of the upper punch.

[0018] If the upper end surface of the first core and the lower end surface of the upper punch are not in contact with each other, the first core is not affected by the movement of the upper punch.

[0019] (5) In any of the powder molding apparatuses described in (1) to (4), the first core may be inserted into the hollow portion so as to divide the hollow portion into a plurality of segments arranged in parallel in a direction perpendicular to the first direction.

[0020] When the hollow portion is divided into multiple segments, multiple powder compacts can be produced in a single compression. The protrusions on the first core are provided corresponding to each segment. Therefore, powder compacts having undercut shapes can be efficiently produced. When multiple powder compacts are produced in a single compression, the resistance force from the powder acting on the protrusions on the first core tends to be large. Because the drive mechanism can move the first core along the first direction, the first core can be moved so that the protrusions are positioned appropriately, regardless of the magnitude of the resistance force.

[0021] (6) The powder molding manufacturing apparatus according to any one of (1) to (5) above may further include a second core inserted in the hollow portion in parallel with the first core.

[0022] The provision of the second core increases the degree of freedom in the shape of the powder compact to be manufactured, and in particular, the provision of the second core makes it possible to manufacture a powder compact having a through hole or a blind hole along the first direction.

[0023] (7) A method for manufacturing a powder compact according to an embodiment of the present disclosure includes the steps of: preparing an apparatus for manufacturing a powder compact according to any one of (1) to (6), filling the hollow portion into which the first core and the lower punch are inserted with the powder, compressing the powder with the upper punch and the lower punch to form a powder compact, and moving the die and the upper punch relative to the lower punch to remove the powder compact. In the step of forming the powder compact, the first core is moved to a predetermined position by the drive mechanism.

[0024] The method for manufacturing a powder compact of the present disclosure uses the powder compact manufacturing apparatus of the present disclosure, and therefore can manufacture a powder compact having an undercut shape with high precision and efficiency.

[0025] [Details of the embodiments of the present disclosure] Specific examples of the powder compact manufacturing apparatus of the present disclosure and the powder compact manufacturing method using the powder compact manufacturing apparatus of the present disclosure will be described with reference to the drawings. The same reference numerals in the figures indicate the same or equivalent parts. In each drawing, for the convenience of explanation, some components may be exaggerated or simplified. The dimensional ratios of each part in the drawings may also differ from the actual ratios. Note that the present invention is not limited to these examples, but is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0026] <Apparatus for Manufacturing Powder Compact> An apparatus for manufacturing powder compacts 1 according to an embodiment will be described with reference to Figures 1 to 5. Figures 6 and 7 will be referred to as appropriate for a powder compact 10 manufactured by the apparatus for manufacturing powder compacts 1. The apparatus for manufacturing powder compacts 1 includes a die 2, an upper punch 3, a lower punch 4, and a first core 5. The apparatus for manufacturing powder compacts 1 according to this embodiment further includes a second core 6.

[0027] In the powder compact manufacturing apparatus 1 shown in Figure 1, the upper punch 3, the lower punch 4, the first core 5, and the second core 6 are not inserted into the die 2. In the powder compact manufacturing apparatus 1 shown in Figure 2, the lower punch 4, the first core 5, and the second core 6 are inserted into the die 2, but the upper punch 3 is not inserted into the die 2. As shown in Figure 1, the die 2 has a hollow portion 20 that penetrates in a first direction D1. As shown in Figure 2, the first core 5 and the second core 6 are inserted into the hollow portion 20 parallel to each other along the first direction D1.

[0028] FIG. 3 shows the state in which the hollow portion 20 formed by inserting the lower punch 4, first core 5, and second core 6 into the die 2 is filled with powder 7P, and the upper punch 3 is being lowered. FIG. 4 shows the state in which the upper punch 3 is further lowered from the state shown in FIG. 3 to compress the powder 7P between the upper punch 3 and the lower punch 4, and the first core 5 is moved to a predetermined position. FIG. 5 shows a cross section of the die 2, upper punch 3, first core 5, and second core 6 in the powder compact manufacturing apparatus 1 shown in FIG. 4 , taken along a plane perpendicular to the first direction D1 and above the protrusion 55 of the first core 5. In FIG. 5, the protrusion 55 is indicated by a dashed line. FIG. 6 shows the state in which the manufactured powder compact 10 is being removed. FIG. 7 shows one of the powder compacts 10 manufactured by the powder compact manufacturing apparatus 1.

[0029] The first core 5 has a protrusion 55. The protrusion 55 protrudes from the side surfaces 51 and 52 of the first core 5 in a direction intersecting the first direction D1. The protrusion 55 imparts an undercut shape to the powder compact 10 shown in FIGS. 6 and 7 . As shown in FIG. 2 , a cavity is formed in the hollow portion 20 by the die 2, the lower punch 4, the first core 5, and the second core 6. In this example, the cavity has a first cavity 73 and a second cavity 74. As shown in FIG. 3 , the first cavity 73 and the second cavity 74 are filled with powder 7P. As shown in FIG. 4 , the upper punch 3 and the lower punch 4 compress the powder 7P filled in the first cavity 73 and the second cavity 74, thereby producing a total of two powder compacts 10 (see FIG. 6 ).

[0030] One of the features of the powder molding manufacturing apparatus 1 of the embodiment is that it includes a drive mechanism 8 that moves the first core 5 along the first direction D1. The drive mechanism 8 includes a cylinder 80 that applies power to the first core 5 so that the first core 5 moves independently of the die 2, the upper punch 3, the lower punch 4, and the second core 6.

[0031] As shown in FIG. 1 , the first direction D1 is the direction in which the hollow portion 20 in the die 2 penetrates. The first direction D1 is a vertical direction. The first direction D1 is the direction in which the upper punch 3 and the lower punch 4 move relative to the die 2, compressing the powder 7P. The second direction D2 shown in the drawings is a direction perpendicular to the first direction D1, in which the first core 5 and the second core 6 are aligned. The third direction D3 shown in the drawings is a direction perpendicular to both the first direction D1 and the second direction D2. In the drawings, the first direction D1, the second direction D2, and the third direction D3 are indicated by single arrows. The opposite directions of the first direction D1, the second direction D2, and the third direction D3 are also referred to as the first direction D1, the second direction D2, and the third direction D3, respectively. FIGS. 1 to 4 show the powder compact manufacturing apparatus 1 cut along a plane along the first direction D1. For ease of explanation, the cylinder 80 is shown in a side view in FIGS. 1 to 4 .

[0032] <Die> As shown in FIG. 1 , the die 2 is a cylindrical member having a hollow portion 20 penetrating in a first direction D1. The hollow portion 20 has an end that opens upward and an end that opens downward. The hollow portion 20 is a space with both ends open. The shape of the hollow portion 20 corresponds to the outer shape of the powder compact 10 to be compression-molded. The inner surface 21 of the die 2 is, for example, a smooth surface without irregularities. The opening edge of the hollow portion 20 as viewed from the first direction D1 may be a straight line, a curved line, or a combination of multiple straight lines and curved lines. In this example, the shape of the opening edge is generally rectangular, as shown in FIG. 5 , and includes four straight lines and four curved lines.

[0033] The die 2 is moved along a first direction D1 by a driving mechanism (not shown).

[0034] <Upper Punch> The upper punch 3 is inserted into the upper part of the hollow portion 20. If the hollow portion 20 is divided into multiple segments 7 by a first core 5 (described later), multiple upper punches 3 are provided corresponding to the number of the multiple segments 7. In this example, the hollow portion 20 is divided into a first segment 71 and a second segment 72, as shown in FIGS. 2 and 5 . As shown in FIG. 5 , the first segment 71 and the second segment 72 are columnar spaces with rectangular cross sections. One powder compact 10 is produced in the first segment 71, and another powder compact 10 is produced in the second segment 72. In this example, a total of two powder compacts 10 are produced, corresponding to the number of first segments 71 and second segments 72 (see FIG. 6 ). The upper punch 3 in this example includes a first upper punch 31 and a second upper punch 32, corresponding to the first segment 71 and the second segment 72. If the hollow portion 20 is not divided, the number of upper punches 3 is one.

[0035] Each of the first upper punch 31 and the second upper punch 32 is a columnar or cylindrical member. In this example, each of the first upper punch 31 and the second upper punch 32 is a cylindrical member into which a portion of the second core 6, which will be described later, is inserted. The outer shape of each end face of the first upper punch 31 and the second upper punch 32 corresponds to the outer shape of the first end face 11 of the powder compact 10 to be compression-molded. In this example, the outer shape of each end face of the first upper punch 31 and the second upper punch 32 is substantially rectangular. The term "substantially rectangular" includes a range that can be considered substantially rectangular, including shapes with chamfered corners or shapes with rounded corners.

[0036] 3 and 4, a part of the first core 5 is inserted between the first upper punch 31 and the second upper punch 32. The first upper punch 31 and the second upper punch 32 are arranged with a gap therebetween that allows a part of the first core 5 to slide freely.

[0037] In this example, each of the first upper punch 31 and the second upper punch 32 is provided with a through hole 34. A part of the second core 6, which will be described later, is slidably inserted into the through hole 34.

[0038] Each of the first upper punch 31 and the second upper punch 32 slides along a first direction D1 relative to the die 2, the first core 5, and the second core 6.

[0039] The first upper punch 31 and the second upper punch 32 are moved along the first direction D1 by a drive mechanism (not shown). The drive mechanism includes, for example, a ram. The first upper punch 31 and the second upper punch 32 may be operated in conjunction with each other. For example, the upper end of the first upper punch 31 and the upper end of the second upper punch 32 are connected to an upper plate 37, and the upper plate 37 is connected to a drive mechanism (not shown). When the upper plate 37 is moved along the first direction D1 by the drive mechanism, the first upper punch 31 and the second upper punch 32 are simultaneously moved along the first direction D1 in conjunction with the upper plate 37.

[0040] The first upper punch 31 and the second upper punch 32 may move independently of each other. For example, the upper end of the first upper punch 31 may be connected to the first upper plate, and the upper end of the second upper punch 32 may be connected to the second upper plate. The first upper plate and the second upper plate are moved along the first direction D1 by different drive mechanisms. Even if the first upper punch 31 and the second upper punch 32 move independently of each other, compression by the first upper punch 31 and compression by the second upper punch 32 may be performed simultaneously. Simultaneous compression makes it easier to compress the powder 7P in the first cavity 73 and the second cavity 74 evenly.

[0041] <Lower Punch> The lower punch 4 is inserted into the lower part of the hollow portion 20. When the hollow portion 20 is divided into a plurality of segments 7 by a first core 5 described below, a plurality of lower punches 4 are provided corresponding to the number of the plurality of segments 7. The lower punch 4 in this example includes a first lower punch 41 and a second lower punch 42 corresponding to the first segment 71 and the second segment 72. The first upper punch 31 and the first lower punch 41 form a pair. The second upper punch 32 and the second lower punch 42 form a pair. When the hollow portion 20 is not divided, the number of lower punches 4 is one.

[0042] Each of the first lower punch 41 and the second lower punch 42 is a columnar or cylindrical member. In this example, each of the first lower punch 41 and the second lower punch 42 is a cylindrical member into which a portion of the second core 6, which will be described later, is inserted. The outer shape of each end face of the first lower punch 41 and the second lower punch 42 corresponds to the outer shape of the second end face 12 of the powder compact 10 to be compression-molded. The second end face 12 is the surface facing the first end face 11 of the powder compact 10. In this example, the outer shape of each end face of the first lower punch 41 and the second lower punch 42 is approximately rectangular.

[0043] 3 and 4, a portion of the first core 5 is inserted between the first lower punch 41 and the second lower punch 42. The first lower punch 41 and the second lower punch 42 are arranged with a gap therebetween that allows a portion of the first core 5 to slide freely. The first core 5 in this example is inserted into the hollow portion 20 from the same direction as the lower punch 4. Therefore, the first core 5 in this example is always arranged between the first lower punch 41 and the second lower punch 42. In other words, the first lower punch 41 and the second lower punch 42 in this example slidably sandwich the first core 5 therebetween.

[0044] In this example, each of the first lower punch 41 and the second lower punch 42 is provided with a through hole 44. A portion of a second core 6, which will be described later, is slidably inserted into the through hole 44. The second core 6 in this example is inserted into the hollow portion 20 from the same direction as the lower punch 4. Therefore, the second core 6 in this example is always disposed inside each of the through holes 44 of the first lower punch 41 and the second lower punch 42.

[0045] The lower punch 4 is usually fixed. The die 2, upper punch 3, first core 5, and second core 6 move relative to the lower punch 4 along a first direction D1. In this example, the lower end of the first lower punch 41 and the lower end of the second lower punch 42 are connected to a base plate 47. The base plate 47 is stationary. The second core 6 slidably passes through the base plate 47.

[0046] 2 and 3 , the first core 5 is a columnar member that is inserted into the hollow portion 20 along the first direction D1. In this example, the first core 5 is inserted into the hollow portion 20 from the same direction as the lower punch 4. In other words, the first core 5 is inserted into the hollow portion 20 from below the die 2.

[0047] In this example, the first core 5 is inserted into the hollow portion 20 so as to divide the hollow portion 20 into a plurality of segments 7. The plurality of segments 7 are arranged in parallel in the second direction D2. In this example, the first core 5 is disposed at a position that divides the hollow portion 20 into two segments 7, a first segment 71 and a second segment 72. Cavities are formed corresponding to the number of segments 7, in this example, a first cavity 73 and a second cavity 74.

[0048] The shape of the first core 5 is determined according to the shape and number of the powder compacts 10 to be compression-molded. The shape of the first core 5 in this example is a substantially rectangular parallelepiped. The term "substantially rectangular parallelepiped" encompasses shapes that are essentially considered rectangular parallelepipeds, including shapes with chamfered or rounded corners. As shown in FIG. 5 , the first core 5 in this example has a side surface 51 facing the first segment 71, a side surface 52 facing the second segment 72, and sliding surfaces 53, 53 facing the die 2, and further has an upper end surface 54 shown in FIGS. 1 to 4 . As shown in FIG. 5 , the first core 5 in this example has a substantially rectangular cross-sectional shape in which the length in the third direction D3 is longer than the length in the second direction D2.

[0049] As shown in FIGS. 1 to 4 , the first core 5 has protrusions 55 provided on the side surfaces 51, 52. The protrusions 55 protrude from the side surfaces 51, 52 in a direction intersecting the first direction D1. The protrusions 55 protrude in the second direction D2. The protrusions 55 are provided midway in the first direction D1 on the side surfaces 51, 52. The shape of the protrusions 55 is not important. The protrusions 55 have, for example, a curved, bulging cross-sectional shape. More specifically, the protrusions 55 in this example are columnar pieces having a bow-shaped cross-sectional shape surrounded by a circular arc and a chord.

[0050] The protrusions 55 provide the undercut portions 15 to the powder compact 10 that is compression-molded. The undercut portions 15 have an undercut shape. The undercut shape is a concave shape that is recessed in a direction intersecting the first direction D1.

[0051] In this example, the protrusions 55 are provided so as to protrude in the second direction D2 and extend in the third direction D3. In this example, the protrusions 55 are columnar pieces having an arched cross-sectional shape and extending along the third direction D3. The protrusions 55 may be provided so as to extend at an angle in a direction intersecting the third direction D3. In this example, the shapes of the protrusions 55 provided on the side surfaces 51 and 52 are the same. In this example, the sizes of the protrusions 55 provided on the side surfaces 51 and 52 are the same. In this example, the protrusions 55 provided on the side surfaces 51 and 52 are symmetrically arranged. When the protrusions 55 provided on the side surfaces 51 and 52 have the same shape, size, and arrangement, multiple powder compacts 10 having the same undercut portions 15 can be simultaneously manufactured. If the protrusions 55 provided on the side surface 51 and the protrusions 55 provided on the side surface 52 have the same shape, size, and arrangement, excessive stress is unlikely to act on the first core 5. This is because, when the powder 7P shown in Figures 3 and 4 is compressed, the stress acting on the first core 5 acts substantially uniformly on the side surfaces 51 and 52. The protrusions 55 provided on the side surface 51 and the protrusions 55 provided on the side surface 52 do not need to have exactly the same shape and size.

[0052] At least one protrusion 55 is provided on each of the side surfaces 51, 52. As in this example, one protrusion 55 may be provided on each of the side surfaces 51, 52. A plurality of protrusions 55 may be provided on each of the side surfaces 51, 52, for example, divided in the first direction D1 or divided in the third direction D3.

[0053] In this example, the first segment 71 and the second segment 72 are symmetrical with respect to the first core 5. In this example, the shape of the first segment 71 and the shape of the second segment 72 are the same. In this example, the size of the first segment 71 and the size of the second segment 72 are the same. The orientation of the first segment 71 and the orientation of the second segment 72 may be different. In this example, the orientation of the first segment 71 and the orientation of the second segment 72 are symmetrical with respect to the first core 5.

[0054] As shown in FIG. 2 , when the first lower punch 41 is placed on the first segment 71, a first cavity 73 is formed in the first segment 71. When the second lower punch 42 is placed on the second segment 72, a second cavity 74 is formed in the second segment 72. In this example, a second core 6 is further placed in each of the first segment 71 and the second segment 72. In this example, the first cavity 73 and the second cavity 74 are rectangular cylindrical spaces. In this example, the first cavity 73 and the second cavity 74 have the same shape. In this example, the first cavity 73 and the second cavity 74 each have a cylindrical shape. The powder compact manufacturing apparatus 1 of this example can simultaneously mold two powder compacts 10 of the same shape and size.

[0055] The plurality of segments 7 may include segments 7 of different shapes. For example, the shape of the first segment 71 may be different from the shape of the second segment 72. The plurality of segments 7 may include segments 7 of different sizes. For example, the size of the first segment 71 may be different from the size of the second segment 72.

[0056] The first core 5 may be inserted into the hollow portion 20 so as to divide the hollow portion 20 into three or more segments 7. The three or more segments 7 may be arranged side by side in the second direction D2. For example, when two first cores 5 shown in FIG. 1 and the like are arranged side by side in the second direction D2, the hollow portion 20 is divided into three segments 7, and three powder compacts 10 are produced. In this case, as an example, the two powder compacts 10 produced in the outer segments 7 have one undercut portion 15 as shown in FIG. 7 , while the powder compact 10 produced in the middle segment 7 has two undercut portions 15, one on each of the opposing side surfaces. Alternatively, two first cores 5 having different numbers of protrusions 55 may be arranged side by side in the second direction D2. One of the two first cores 5 has a protrusion 55 on each of the side surfaces 51 and 52 as shown in FIG. 1 and the like, and the remaining one of the two first cores 5 has a protrusion 55 only on the side surface 52. When two first cores 5 having different numbers of protrusions 55 are arranged in parallel in the second direction D2, three powder compacts 10 each having one undercut portion 15 are produced as shown in FIG.

[0057] Three or more segments 7 may be arranged in parallel around the central axis of the hollow portion 20. For example, in the case of a hollow portion 20 having a rectangular cross section, if the first core 5 is a cross-shaped columnar member, the hollow portion 20 is divided into four segments 7, and four powder compacts 10 are produced.

[0058] The hollow portion 20 does not have to be divided. For example, in the case where the hollow portion 20 has a rectangular cross section, if the first core 5 is inserted biasedly to one side of the hollow portion 20, one segment 7 is formed in the region of the hollow portion 20 where the first core 5 is not inserted. One cavity is formed in the hollow portion 20.

[0059] The first core 5 is moved in the first direction D1 by a drive mechanism 8, which will be described later. The drive mechanism 8 includes a cylinder 80. For example, the lower end of the first core 5 is connected to the lower plate 57, and the lower end of the cylinder 80 is able to come into contact with the lower plate 57. The lower plate 57 is pushed down by the cylinder 80. As the lower plate 57 moves in the first direction D1 by the cylinder 80, the first core 5 moves in the first direction D1 in conjunction with the lower plate 57. The movement of the first core 5 will be described in detail. The lower punch 4 and the second core 6 slidably pass through the lower plate 57.

[0060] The upper end surface 54 of the first core 5 does not contact other components of the powder compact manufacturing apparatus 1. Therefore, the upper end surface 54 of the first core does not contact the lower end surface of the upper punch 3. If the upper end surface 54 of the first core 5 and the lower end surface of the upper punch 3 do not contact each other, the first core 5 is not affected by the movement of the upper punch 3. If the upper end surface 54 of the first core 5 and the lower end surface of the upper punch 3 do not contact each other, the upper end surface 54 of the first core 5 does not wear. The upper end surface 54 of the first core 5 does not contact the lower end surface of the upper punch 3 throughout the entire process, from when the powder 7P is filled into the cavities, in this example, the first cavity 73 and the second cavity 74, until the compression-molded powder compact 10 is removed.

[0061] <<Second Core>> As shown in FIGS. 1 to 4 , the second core 6 is a columnar member inserted into the hollow portion 20 in parallel with the first core 5. The second core 6 is inserted into the hollow portion 20 from the same direction as the lower punch 4. That is, the second core 6 is inserted into the hollow portion 20 from below the die 2. The length of the second core 6 along the first direction D1 is longer than the length of the lower punch 4 along the first direction D1. The second core 6 is structured to be fitted into the hollow portion 20 together with the lower punch 4 and the first core 5 from the same direction as the lower punch 4. When the hollow portion 20 is divided into multiple segments 7 by the first core 5, multiple second cores 6 are provided corresponding to the number of the multiple segments 7. The second core 6 is inserted into each of the through holes 44 of the first lower punch 41 and the second lower punch 42. The second core 6 forms a through hole 16 in the powder compact 10 to be compression-molded. The shape of the second core 6 corresponds to the shape of the through hole 16. The second core 6 in this example has a cylindrical shape.

[0062] The two second cores 6 are moved along the first direction D1 by a drive mechanism (not shown). The drive mechanism includes, for example, a ram. The two second cores 6 may be operated in conjunction with each other. For example, the lower ends of the two second cores 6 are connected to a yoke plate 67, and the yoke plate 67 is connected to a drive mechanism (not shown). When the yoke plate 67 is moved along the first direction D1 by the drive mechanism, the two second cores 6 are simultaneously moved along the first direction D1 in conjunction with the yoke plate 67.

[0063] <<Drive Mechanism>> The drive mechanism 8 is a mechanism that moves the first core 5 along the first direction D1. The drive mechanism 8 includes a cylinder 80. The cylinder 80 applies power to the first core 5 so that it moves independently of the die 2, the upper punch 3, the lower punch 4, and the second core 6. In the cylinder 80, a piston reciprocates within a hollow cylindrical body by air pressure or hydraulic pressure. The piston moves along the first direction D1.

[0064] The drive mechanism 8 of this example includes a lower plate 57. The upper end of a cylinder 80 is supported by the upper plate 57. The lower end of the cylinder 80 can freely contact the lower plate 57 by extending the piston. As shown in FIG. 4 , when the cylinder 80 moves downward in the first direction D1, the lower end of the cylinder 80 presses the lower plate 57 down in the first direction D1. When the lower plate 57 moves down in the first direction D1, the first core 5 moves down in the first direction D1 in conjunction with the lower plate 57.

[0065] <Powder molded body> As shown in Fig. 7 , the powder molded body 10 manufactured by the above-described powder molded body manufacturing apparatus 1 includes an undercut portion 15. The undercut portion 15 is a recess recessed from the side surface 13. The powder molded body 10 of this example further includes a through hole 16.

[0066] <Method for Manufacturing Powder Compact> A method for manufacturing a powder compact according to an embodiment will be described with reference to Figures 1 to 4 and 6. The method for manufacturing a powder compact includes a preparation step, a filling step, a molding step, and a removal step, which are performed in this order.

[0067] <Preparation Step> In the preparation step, the above-described powder compact manufacturing apparatus 1 is prepared. The shapes of the die 2, upper punch 3, lower punch 4, first core 5, and second core 6 can be appropriately selected to correspond to the shape of the powder compact 10 to be manufactured.

[0068] <<Filling Process>> In the filling process, the hollow portion 20 shown in FIG. 1 is filled with powder 7P (FIG. 3) by inserting the lower punch 4 and the first core 5 into the hollow portion 20. As shown in FIG. 2, the hollow portion 20 into which the lower punch 4 and the first core 5 are inserted is a cavity, which in this example is a first cavity 73 and a second cavity 74. In this example, a second core 6 is also inserted into the hollow portion 20. The upper end surface of the second core 6 is positioned higher than the upper end surface of the lower punch 4. The upper end surface 54 of the first core 5 and the upper end surface of the second core 6 are flush with the upper end surface of the die 2, for example.

[0069] <<Molding Process>> The molding process includes a first process of lowering the upper punch 3, a second process of lowering the cylinder 80 of the drive mechanism 8, and a third process of compressing the powder 7P with the upper punch 3 and the lower punch 4. In the molding process, the first core 5 needs to be positioned at a predetermined position when the powder 7P is compressed with the upper punch 3 and the lower punch 4. To adjust the position of the first core 5, the drive mechanism 8 moves the first core 5 to a predetermined position. To move the first core 5 to a predetermined position, the drive mechanism 8 lowers the first core 5.

[0070] The length of the cylinder 80 may be adjusted in advance to determine the timing of the descent of the upper punch 3 and the first core 5. In this case, as the upper punch 3 descends, the lower end of the cylinder 80, whose length has been adjusted in advance, reaches the lower plate 57, causing the lower end of the cylinder 80 to press down on the lower plate 57, causing the upper punch 3 and the first core 5 to descend in unison. The first and second steps may be performed simultaneously. For example, the cylinder 80 may be operated to lower the first core 5 while the upper punch 3 is being lowered. The second and third steps may be performed simultaneously. Furthermore, the first, second, and third steps may be performed in unison without a clear division between them. For example, in the third step, the lower punch 4 remains stationary, and the die 2, upper punch 3, and second core 6 are lowered. In the third step, the cylinder 80 may be operated to lower the first core 5 at the timing when the powder 7P is compressed by the upper punch 3. After the powder 7P is compression-molded by the upper punch 3 and the lower punch 4, the first core 5 is not lowered.

[0071] When compressing the powder 7P, resistance from the powder 7P is applied below the protrusion 55 of the first core 5. By forcibly moving the first core 5 downward using the drive mechanism 8, the protrusion 55 is positioned appropriately when compressing the powder 7P, even if resistance from the powder 7P is applied below the protrusion 55. Therefore, in the manufactured powder compact 10, the undercut portion 15 is positioned at a predetermined position with high precision. The timing for moving the first core 5 is adjusted independently of the timing for moving components other than the first core 5. If the timing for moving the first core 5 can be adjusted independently, the powder 7P can be compressed appropriately regardless of the shape and size of the protrusion 55 of the first core 5.

[0072] In this example, the powder 7P in the first cavity 73 is compressed by the first upper punch 31 and the first lower punch 41, and the powder 7P in the second cavity 74 is compressed by the second upper punch 32 and the second lower punch 42. In this example, two powder compacts 10 are molded simultaneously.

[0073] 6, in the removal process, the die 2, the upper punch 3, and the second core 6 are moved relative to the lower punch 4. Specifically, with the lower punch 4 and the first core 5 fixed, the upper punch 3 is raised along the first direction D1, and the die 2 and the second core 6 are lowered along the first direction D1.

[0074] The removal step positions each powder compact 10 outside the hollow portion 20 of the die 2. The surfaces of each powder compact 10 positioned outside the hollow portion 20 are exposed except for the surface in contact with the first core 5. Each powder compact 10 positioned outside the hollow portion 20 can be moved away from the first core 5. Each powder compact 10 can be removed by peeling it off the first core 5. In this example, two powder compacts 10 are moved away from each other along the second direction D2. This removal step allows the powder compact 10 having the undercut portion 15 shown in FIG. 7 to be easily removed from the powder compact manufacturing apparatus 1.

[0075] After the powder compact 10 is removed from the powder compact manufacturing apparatus 1, the lower plate 57 is returned to a predetermined position. The predetermined position of the lower plate 57 is the position before it is pressed down by the cylinder 80 in the molding process. A cylinder (not shown) is disposed below the lower plate 57 for pushing up the lower plate 57. After the powder compact 10 is removed from the powder compact manufacturing apparatus 1, the lower plate 57 that was pressed down by the cylinder 80 in the molding process is pushed up to a predetermined position immediately before filling the cavity with powder 7P in the process of manufacturing the next powder compact 10.

[0076] DESCRIPTION OF SYMBOLS 1 Powder compact manufacturing apparatus 2 Die 20 Hollow portion 21 Inner surface 3 Upper punch 31 First upper punch 32 Second upper punch 34 Through hole 37 Upper plate 4 Lower punch 41 First lower punch 42 Second lower punch 44 Through hole 47 Base plate 5 First core 51, 52 Side surface 53 Sliding surface 54 Upper end surface 55 Protrusion 57 Lower plate 6 Second core 67 Yoke plate 7 Segment 71 First segment 72 Second segment 73 First cavity 74 Second cavity 7P Powder 8 Drive mechanism 80 Cylinder 10 Powder compact 11 First end surface 12 Second end surface 13 Side surface 15 Undercut portion 16 Through hole D1 First direction D2 Second direction D3 Third direction

Claims

1. An apparatus for manufacturing a powder compact, comprising: a die having a hollow portion penetrating in a first direction; a first core inserted into the hollow portion along the first direction; an upper punch and a lower punch that compress powder placed in the hollow portion; and a drive mechanism that moves the first core along the first direction, wherein the first core has a protrusion that protrudes from a side surface of the first core in a direction intersecting the first direction, and the drive mechanism has a cylinder that imparts power to the first core so that it moves independently of the die, the upper punch, and the lower punch.

2. The powder molding device according to claim 1, wherein the first core is inserted into the hollow portion from the same direction as the lower punch, the drive mechanism includes a lower plate connected to the lower end of the first core, and the cylinder moves the lower plate along the first direction.

3. The powder molding device according to claim 2, wherein the upper end of the cylinder is supported by an upper plate connected to the upper end of the upper punch, and the lower end of the cylinder is freely in contact with the lower plate.

4. An apparatus for manufacturing powder compacts according to any one of claims 1 to 3, wherein the upper end surface of the first core is not in contact with the lower end surface of the upper punch.

5. A powder molding manufacturing apparatus as described in any one of claims 1 to 4, wherein the first core is inserted into the hollow portion so as to divide the hollow portion into a plurality of segments arranged side by side in a direction perpendicular to the first direction.

6. An apparatus for manufacturing powder moldings according to any one of claims 1 to 5, further comprising a second core inserted in the hollow portion in parallel with the first core.

7. A method for manufacturing a powder compact, comprising the steps of: preparing a manufacturing apparatus for a powder compact as described in any one of claims 1 to 6; filling the powder into the hollow portion into which the first core and the lower punch are inserted; compressing the powder with the upper punch and the lower punch to form a powder compact; and moving the die and the upper punch relative to the lower punch and removing the powder compact, wherein in the step of forming the powder compact, the first core is moved to a predetermined position by the drive mechanism.

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