JP2013018045A - Molding die device of green compact of curved plate-like component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compress and mold raw powder of high hardness such as magnetic powder at a high pressure without generating a crack starting from an inner corner part of a die even when compression molding is carried out at the high pressure.SOLUTION: A recessed-shape cavity 30 is formed on an outer circumference surface 21 of a core rod 20. The raw powder, which is supplied to the cavity 30 by upper and lower punches slidably inserted in the cavity 30, is compressed to mold the green compact of the curved plate-like component. By forming the right-angled inner corner part 34 of the cavity 30 by an inner circumference surface 11 of a dice 10 and the outer circumference surface 21 of the core rod 20, stress applied on the inner corner part 34 in compression molding is leaked to a joint boundary surface 60 of the inner circumference surface 11 of the dice 10 and the outer circumference surface 21 of the core rod 20 to prevent generation of the crack starting from the inner corner part 34, and mold at the high pressure.

Description

  The present invention relates to a green compact mold apparatus used when compression molding a raw material powder into a green compact approximate to the part in the process of obtaining a curved plate-shaped part by powder metallurgy.

  The powder metallurgy method, which compresses the raw material powder supplied to the cavity in the mold with a punch to form a green compact that approximates the target part shape and sinters this green compact to obtain a part, is precise, It is also known as a method capable of mass production of complicated shapes. For example, for cylindrical parts such as bearings, raw material powder is supplied to a cylindrical cavity formed in a die of a mold and opened in the vertical direction, and the upper and lower punches are slidably inserted into the cavity. Are molded in the axial direction (see Patent Document 1).

  Now, it has been attempted to manufacture the curved plate-like part by powder metallurgy. The curved plate-like component in this case is, for example, a rectangular plate having a uniform thickness and having a shape in which one side is straight and the other side is curved in an R shape as indicated by reference numeral 100 in FIG. In other words, it means a shape obtained by cutting a part of a cylinder into a rectangular shape.

  In order to form the green compact of the curved plate-like component 100 by applying a conventional green compact molding method, as shown in FIGS. 21 and 22, the curved plate-like component formed in the die 110 is used. The raw material powder P is supplied to the cavity 130 corresponding to the above, and the raw material powder P is compressed by the upper and lower punches 140 and 150 inserted into the cavity 130. The cavity 130 is formed in a state where the linear one side direction is along the vertical direction, and therefore the raw material powder P is compressed in the axial direction like the cylindrical part.

JP 2004-251302 A

  By the way, a raw material powder having high hardness such as magnetic powder has a characteristic that it is difficult to increase the density because it is difficult to be plastically deformed. In the case of compressing and molding such a high-hardness raw material powder, the raw material powder is compressed at a pressure higher than usual to obtain a green compact. However, when the green compact of the curved plate-like component 100 as shown in FIG. 20 is molded by the mold apparatus shown in FIGS. 21 and 22 with the raw material powder having high hardness, as shown in FIG. In some cases, stress due to the punch pressure is concentrated on the right-angle inner corners 131 and 132 of the cavity 130 of the die 110, and cracks (indicated by arrows H) may occur starting from the inner corners 131 and 132. Since the die having cracks becomes unusable, and thus causes problems such as high cost and low productivity, an improvement measure has been demanded.

  The present invention has been made in view of the above circumstances, and its main purpose is to prevent the occurrence of cracks starting from the inner corner of the mold even when compression molding is performed at a high pressure, such as magnetic powder. An object of the present invention is to provide a green compact molding apparatus for curved plate-like parts, which can accurately mold a high hardness raw material powder.

  A green compact molding apparatus for a curved plate-shaped part according to the present invention is a mold apparatus for molding a green compact of a curved plate-shaped part, and a die having a hollow portion formed by a cylindrical inner peripheral surface. And a core rod having a cylindrical outer peripheral surface and slidably inserted into the hollow portion of the die, and a punch having a shape corresponding to the curved plate-like component, the inner peripheral surface of the die Alternatively, a cavity having a shape corresponding to the curved plate-like component is formed in one of the outer peripheral surfaces of the core rod in a concave shape, and between the die and the core rod between the circumferential directions of the cavity. A curved plate-like convex part that closes a part of the cavity to form the inner side surface of the cavity is disposed, and in the mold set state in which the core rod is inserted into the hollow part of the die, the cavity is connected to the die. Partitioned by the core rod Wherein the raw material powder supplied to the cavity is the curved plate-like part of the green compact is compressed in the axial direction is formed by the punch.

  In the present invention, when the cavity is formed on the inner peripheral surface of the die, the green compact of the curved plate-like component is formed with the outer peripheral surface at the bottom surface of the cavity, and the inner peripheral surface is formed with the outer peripheral surface of the core rod. Both side surfaces are formed by the side surfaces of the convex portion, that is, the inner side surface of the cavity. On the other hand, when the cavity is formed on the outer peripheral surface of the core rod, the green compact of the curved plate-shaped part is formed by the inner peripheral surface of the die and the inner peripheral surface is formed by the bottom surface of the core rod cavity. Both side surfaces are formed on the inner surface of the cavity.

  There are two inner corners at both ends in the circumferential direction of the cavity of the mold of the present invention, an inner corner formed by a die and a core rod, and an inner corner formed by a bottom surface and an inner side surface of the cavity. Among these, the inner corner of the former is formed of a die and a core rod to be divided, and a joining boundary surface between the die and the core rod extends outward from the inner corner. For this reason, when the raw material powder is compression molded with a punch, if stress is applied to the inner corner formed by the die and the core rod, the stress leaks to the above-mentioned joint boundary surface, and stress concentration on the inner corner is reduced. Does not happen. As a result, the occurrence of cracks starting from the inner corner is prevented.

  On the other hand, stress is likely to concentrate at the inner corner formed by the bottom surface and the inner surface of the cavity as in the prior art. Therefore, in the present invention, it is preferable that the inner corner formed by the bottom surface and the inner side surface of the cavity is formed in an R shape so that stress is not easily concentrated.

  Further, according to the present invention, the cavity in the mold setting state is opened to one end side in the axial direction, the other end side is closed by a step portion formed on the die or the core rod, and the punch enters the cavity from the opening on the one end side. Includes the form to be inserted. According to this embodiment, a single punch can be formed, and the raw material powder in the cavity is sandwiched between the punch and the stepped portion and compressed in the axial direction.

  In the case where the die or the core rod has the stepped portion, the inner corner portion of the stepped portion is formed in an R shape so that stress concentration on the inner corner portion of the stepped portion can be suppressed.

  Further, when the die or the core rod has the stepped portion, the die or core rod formed with the stepped portion has the stepped portion as a boundary, the body side including the cavity, and the stepped portion side including the stepped portion. In addition, it includes a form that is divided in the axial direction. According to this aspect, the inner corner portion of the step portion is composed of two members of the main body side and the step portion side, and the joint boundary surface between the main body side and the step portion side extends outward from the inner corner portion. . For this reason, stress concentration at the inner corner of the step portion does not occur, and cracks starting from the inner corner are prevented.

  Next, a green compact molding apparatus for a curved plate-shaped part according to the present invention is a mold apparatus for molding a green compact of a curved plate-shaped part, and is a hollow portion formed by a cylindrical inner peripheral surface. A die having a cylindrical outer peripheral surface, a core rod inserted into the hollow portion of the die with a gap between the inner peripheral surface of the die and a slidable insertion into the gap A curved plate-shaped intermediate mold that forms a cavity having a shape corresponding to the curved plate-shaped component, and a punch having a shape corresponding to the curved plate-shaped component, and the hollow portion of the die. In the die set state in which the intermediate die is inserted into the gap formed between the inner peripheral surface of these dies and the outer peripheral surface of the core rod, the inner peripheral surface of the die, the core rod The cavity is defined by the outer peripheral surface of the substrate and the intermediate mold. Wherein the raw material powder supplied to the cavity is the curved plate-like part of the green compact is compressed in the axial direction is formed by the punch.

  In the above invention, the green compact of the curved plate-like component has the outer peripheral surface formed by the inner peripheral surface of the die, the inner peripheral surface formed by the outer peripheral surface of the core rod, and both side surfaces formed by the side surfaces of the intermediate mold. In the mold of the present invention, the inner corners on the outer peripheral side at both ends in the circumferential direction of the cavity are formed by a die and an intermediate mold, and the joint boundary surface between the two extends outward from the inner corner. On the other hand, the inner corner portion on the inner peripheral side is formed by a core rod and an intermediate mold, and the joint interface between the two extends outward from the inner corner portion. That is, both the inner corners on the outer peripheral side and the inner peripheral side are formed of two members, and the joining boundary surfaces of these members extend outward from the inner corner portions. For this reason, stress concentration does not occur in the inner corners, and cracks starting from the inner corners are prevented.

  According to the present invention, it is possible to prevent the occurrence of cracks starting from the inner corner of the mold, and as a result, compression molding at high pressure is possible, and high-hardness raw material powder such as magnetic powder is accurately formed. There is an effect that can be.

It is a top view of the green compact molding die apparatus concerning a 1st embodiment of the present invention. It is a perspective view of the metal mold apparatus of a 1st embodiment. It is a figure corresponding to the AA cross section of FIG. 1, Comprising: (a) The state which supplied raw material powder to the cavity, (b) The state which compression-molded raw material powder with the punch is shown. It is a partially expanded plan view of the core rod of the mold apparatus of the first embodiment. It is a top view which shows the cavity formed with the metal mold apparatus of 1st Embodiment. It is (a) top view of the green compact of the curved plate-shaped component shape | molded with the metal mold apparatus of 1st Embodiment, (b) The front view seen from the inner peripheral surface side, (c) It is a perspective view. It is (a) perspective view which shows the core rod of the modification 1 which changed the core rod in 1st Embodiment of this invention, (b) It is sectional drawing which shows a step part. It is sectional drawing of the metal mold | die apparatus of the modification 1, Comprising: (a) The state which supplied raw material powder to the cavity, (b) The state which compression-molded raw material powder with the punch is shown. It is a disassembled perspective view of the core rod of the modification 2 which changed the core rod in 1st Embodiment of this invention. It is a lower cross-sectional view of the core rod of the second modification. It is a top view of the compacting die device concerning a 2nd embodiment of the present invention. It is a partially expanded plan view of the core rod of the mold apparatus of the second embodiment. It is a top view which shows the cavity formed with the metal mold apparatus of 2nd Embodiment. It is a top view of the green compact of the curved plate-shaped components shape | molded with the metal mold apparatus of 2nd Embodiment. It is a top view of the compacting die device concerning a 3rd embodiment of the present invention. It is a figure corresponding to the BB cross section of FIG. 15, Comprising: (a) The state which supplied raw material powder to the cavity, (b) The state which compression-molded the raw material powder with the punch is shown. It is a top view which shows the cavity formed with the metal mold apparatus of 3rd Embodiment. It is a top view of the green compact of the curved plate-shaped components shape | molded with the metal mold apparatus of 3rd Embodiment. It is a top view which shows the other form of the cavity formed with the metal mold | die apparatus of this invention. It is a figure which shows an example of a curved plate-shaped component, Comprising: (a) Top view, (b) The front view seen from the inner peripheral surface side, (c) It is a perspective view. It is a top view which shows an example of the conventional metal mold | die apparatus for shape | molding the green compact of the curved plate-shaped components shown in FIG. It is a figure corresponding to CC section of FIG. 21, Comprising: (a) The state which supplied raw material powder to the cavity, (b) The state which compression-molded the raw material powder with the punch is shown. It is the D section enlarged view of FIG. 21, Comprising: The state which the crack produced in the inner corner part of the cavity is shown.

  Hereinafter, embodiments (first to third embodiments) according to a green compact mold apparatus for curved plate-like parts of the present invention will be described with reference to the drawings. In any of the embodiments, the same shape as that of the curved plate-like component 100 shown in FIG. 20 is formed from the raw material powder to the green compact.

(1) First Embodiment FIGS. 1 to 3 show a mold apparatus 1 according to a first embodiment of the present invention. The mold apparatus 1 includes a cylindrical die 10 whose axial direction is set along the vertical direction, a columnar core rod 20 that is slidably inserted into the die 10, and a space between the die 10 and the core rod 20. And upper and lower punches 40 and 50 which are slidably inserted into the cavity 30 defined in FIG.

  A hollow portion 15 having a circular cross section is formed through the axis of the die 10. The inner diameter of the inner peripheral surface 11 of the die 10 forming the hollow portion 15 is set to be equal to the outer diameter of the outer peripheral surface of the curved plate-like component to be obtained. The core rod 20 is longer than the axial length of the die 10 and is concentrically and slidably inserted into the hollow portion 15 of the die 10. The outer peripheral surface 21 of the core rod 20 is formed in a cylindrical shape, and the outer peripheral surface 21 slides on the inner peripheral surface 11 of the die 10 when inserted into the die 10. A cavity 30 having a shape corresponding to the curved plate-like component is formed in a concave shape at a plurality of locations (in this case, two locations) equally divided on the outer peripheral surface 21.

  The cavity 30 is formed over the entire length of the core rod 20, and the bottom surface 31 is formed on a peripheral surface concentric with the outer peripheral surface 21 of the core rod 20. The outer diameter of the bottom surface 31 is set to be equal to the inner diameter of the inner peripheral surface of the curved plate-like component to be obtained. Between the circumferential direction of the cavity 30 of the core rod 20, the curved plate-shaped convex part 22 is formed over the full length of the core rod 20. As shown in FIG. As shown in FIG. 4, the side surface of the convex portion 22 forms the inner side surface 32 of the cavity 30. The outer peripheral surface of the convex portion 22 constitutes the outer peripheral surface 21 of the core rod 20. When the core rod 20 is inserted into the hollow portion 15 of the die 10, the outer peripheral surface 21 slides on the inner peripheral surface 11 of the die 10 as described above, and the convex portion 22 is partially formed between the die 10 and the core rod 20. It becomes the state blocked by.

  As shown in FIG. 5, inner corners 33 on the inner circumferential side at both circumferential ends formed by the bottom surface 31 and the inner side surface 32 of the cavity 30 are processed into an R shape. In addition, the inner corners 34 on the outer peripheral side at both ends in the circumferential direction formed by the outer peripheral surface 21 of the convex portion 22 and the inner side surface 32 of the cavity 30 of the cavity 30 are formed in a right angle shape.

  The upper and lower punches 40 and 50 have the same configuration and are formed in a curved plate shape corresponding to the curved plate-like component, and have dimensions and shapes that can be fitted into the cavity 30.

  The above is the configuration of the mold apparatus 1 according to the first embodiment. Next, a procedure for molding the green compact of the curved plate-like component by the mold apparatus 1 will be described. First, as shown in FIG. 3A, the core rod 20 is inserted into the hollow portion 15 of the die 10 from the lower side, and the upper end surface of the core rod 20 is adjusted to the height position of the upper end surface of the die 10 so that the mold is set. And In this mold set state, as shown in FIG. 5, the cavity 30 is surrounded and partitioned by the inner peripheral surface 11 of the die 10, the bottom surface 31 and the inner side surface 32 of the cavity 30 of the core rod 20.

  Subsequently, after the upper end portion of the lower punch 50 is inserted into the cavity 30 from the lower side, a predetermined amount of the raw material powder P is supplied to the cavity 30 from the upper opening. Next, as shown in FIG. 3B, the upper punch 40 is inserted into the cavity 30 from the upper side, the lower punch 50 is appropriately raised, and the raw material powder P is sandwiched between the upper and lower punches 40 and 50 in the axial direction. Compress at a predetermined pressure.

  Thereby, the raw material powder P in the cavity 30 is formed into a green compact P1 having a shape approximating a curved plate-like component. Thereafter, the die 10 is lowered relative to the core rod 20, and then the upper and lower punches 40, 50 are raised to extract the green compact from the mold apparatus.

  FIG. 6 shows the obtained green compact P1, and the green compact P1 has a uniform thickness. For example, the outer diameter r1: 15 to 20 mm, the inner diameter r2: 12 to 18 mm, and the thickness t: 1 to 5 mm, circumferential angle α: 100 to 150 °, thin curved plate-like compact with a ratio of outer peripheral length l to thickness t (l / t) of about 5 to 25 Is the body.

  6A and FIG. 5 showing the cavity 30, the green compact P1 has an outer peripheral surface 1a formed by the inner peripheral surface 11 of the die 10 and an inner peripheral surface 1b formed by the core rod 20. The side surface 1 c is formed by the inner side surface 32 of the cavity 30. The outer peripheral corners 1d at both ends in the circumferential direction are formed in an R shape in which the R-shaped inner corner portion 33 of the cavity 30 is transferred and chamfered at right angles, and the outer outer corner portion 1e on the outer peripheral side. Is formed in a right-angled shape by transferring a right-angled inner corner portion 34 formed by the inner side surface 32 of the cavity 30 on the core rod 20 side and the inner peripheral surface 11 of the die 10. The obtained green compact P1 is sintered to obtain a curved plate-like component made of a sintered body.

  According to the mold apparatus of the first embodiment, the outer corners 1e on the outer peripheral side at both ends in the circumferential direction of the green compact P1 are the inner surface 32 of the cavity 30 and the inner peripheral surface 11 of the die 10 as described above. The right-angled inner corner portion 34 formed in (1) is transferred to form a right-angle shape. That is, the inner corner portion 34 on the outer peripheral side of the cavity 30 is formed in a right angle by the dice 10 and the core rod 20 to be divided, and from the inner corner portion 34, as shown in FIG. A joint boundary surface 60 between the inner peripheral surface 11 and the outer peripheral surface 21 of the convex portion 22 of the core rod 20 extends outward along the circumferential direction.

  For this reason, when a stress is applied to the inner corner portion 34 when the raw material powder P is compression-molded by the upper and lower punches 40, 50, the stress leaks from the inner corner portion 34 to the joint boundary surface 60, and the inner Stress concentration at the corner 34 does not occur. As a result, the occurrence of cracks starting from the inner corner 34 is prevented. On the other hand, although the inner corner portion 33 on the inner peripheral side of the cavity 30 is formed only by the core rod 20, it is formed in an R shape, so that stress concentration is less likely to occur. From these facts, it is possible to compression-mold the raw material powder P at a relatively high pressure. For example, even if the raw material powder P is of high hardness such as magnetic powder, the pressure of the target shape can be obtained by compression molding at a high pressure. The powder can be accurately formed. In order to alleviate the stress concentration, the radius of the inner corner 33 formed in the R shape is preferably 1 mm or more, and more preferably 2 mm or more.

  Next, modified examples 1 and 2 in which the configuration of the core rod 20 of the first embodiment in which the cavity 30 is formed are changed will be described.

(2) Modification 1 of the first embodiment
FIG. 7A shows the core rod 20 of the first modification. The core rod 20 is integrated with the convex portion 22 by filling the lower end portion of the cavity 30 in the core rod 20 of the first embodiment, instead of the lower punch 50, and is integrated with the convex portion 22. A closed portion 23 having a continuous outer peripheral surface having the same diameter is formed. The upper end surface of the closing portion 23 is a flat step portion 24 orthogonal to the axial direction. As shown in FIG. 7B, the right-angled inner corner portion 25 formed by the arc-shaped step portion 24 and the bottom surface 31 of the cavity 30 is formed in an R shape.

  FIG. 8A shows a mold setting state of the mold apparatus 1 in which the core rod 20 of the first modification is inserted into the die 10, and the cavity 30 in this case is open to one end side, that is, the upper side in the axial direction. The other end side is closed by a closing portion 23 including a step portion 24 of the core rod 20. The raw material powder P is supplied to the cavity 30 from above, and thereafter, as shown in FIG. 8B, the upper punch 40 is inserted into the cavity 30 from the opening 30a of the cavity 30 and the core rod 20 is appropriately raised. The raw material powder P is sandwiched between the upper punch 40 and the stepped portion 24 of the closing portion 23 and compressed in the axial direction with a predetermined pressure. Thereby, the green compact P1 shown in FIG. 6 is formed.

  According to the first modification, since the lower punch 50 is not required, the punch can be configured by one of the upper punches 40, and thus has an advantage that the configuration is simpler than that of the first embodiment. In addition, since the rectangular inner corner 25 formed by the step 24 of the core rod 20 and the bottom surface 31 of the cavity 30 is formed in an R shape, stress concentration on the inner corner 25 is less likely to occur. Thus, the occurrence of cracks starting from the inner corner 25 is prevented.

(3) Modification 2 of the first embodiment
FIG. 9 shows the core rod 20 of the second modification. In the core rod 20 of the first modification, the core rod 20 is divided into a main body side 26 including the cavity 30 and the convex portion 22 and a step side 28 including the step portion 24 and the closing portion 23 with the step portion 24 as a boundary. The structure is divided in the axial direction. That is, the main body side 26 is formed with the cavity 30 and the convex portion 22, and the stepped portion side 28 is formed in a circular trapezoidal shape having an outer peripheral surface 28 a having the same diameter as the outer peripheral surface 21 of the convex portion 22. As shown in FIG. 10, a disk-shaped protrusion 29 is formed at the center of the upper surface 28b of the step side 28, and a recess 27 into which the protrusion 29 is fitted is formed on the lower surface 26b of the main body side 26. Yes.

  As shown in FIG. 10, the core rod 20 has a projection 29 on the step side 28 fitted in a recess 27 on the lower surface 26 b on the main body side 26, and a lower surface 26 b on the main body side 26 and an upper surface 28 b on the step side 28. Assembled in a combined state. The concave portion 27 and the projection 29 are positioning means for assembling. When the projection 29 is fitted into the concave portion 27, the outer peripheral surfaces 21 and 28a of the main body side 26 and the stepped portion side 28 coincide with each other concentrically. In this assembled state, the core rod 20 has the same shape as that of the core rod 20 of the first modification. As shown in FIG. 10, the arc-shaped outer periphery exposed by the cavity 30 on the upper surface 28 b of the step portion side 28 forms the step portion 24. Configure.

  In the second modification, the core rod 20 is divided into the main body side 26 and the step portion side 28, so that the inner corner formed by the step portion 24 and the bottom surface 31 of the cavity 30 as shown in FIG. Reference numeral 35 denotes a right-angled shape, and from this inner corner portion 35, a joining boundary surface 61 between the lower surface 26b of the main body side 26 and the upper surface 28b of the step portion side 28 extends in a direction perpendicular to the axial direction. Therefore, stress concentration on the inner corner 35 does not occur, and as a result, generation of cracks starting from the inner corner 35 is prevented.

(4) Second Embodiment Next, a mold apparatus according to a second embodiment of the present invention will be described with reference to FIGS.
The mold apparatus 2 of the second embodiment includes the die 10, the core rod 20, and the upper and lower punches 40 and 50, as in the first embodiment, but the raw material powder P is supplied, and the upper and lower punches 40, Unlike the first embodiment, the cavity 30 into which 50 is inserted is formed in the die 10, and the other configurations are the same.

  That is, the cavity 30 having a shape corresponding to the curved plate-like component is formed in a concave shape over the entire length at a plurality of locations (in this case, two locations) equally divided on the inner peripheral surface 11 of the die 10. A bottom surface 31 of the cavity 30 is formed on a peripheral surface concentric with the inner peripheral surface 11 of the die 10. Curved plate-like convex portions 12 are formed between the circumferential directions of the cavities 30, and the side surfaces of the convex portions 12 form inner side surfaces 32 of the cavities 30 as shown in FIG. 12. Further, the inner peripheral surface of the convex portion 12 constitutes the inner peripheral surface 11 of the die 10. When the core rod 20 is inserted into the hollow portion 15 of the die 10, the outer peripheral surface 21 of the core rod 20 slides on the inner peripheral surface 11 of the convex portion 12 of the die 10, and a part between the die 10 and the core rod 20 is partially formed. It will be in the state obstruct | occluded by the convex part 12. FIG.

  As shown in FIGS. 11 and 13, in the mold set state in which the core rod 20 is inserted into the hollow portion 15 of the die 10, the cavity 30 includes an outer peripheral surface 21 of the core rod 20, a bottom surface 31 of the cavity 30 of the die 10, and an inner surface. The upper and lower punches 40, 50 are slidably inserted into the cavity 30.

  As shown in FIG. 13, inner corners 36 on the outer peripheral side of both ends in the circumferential direction formed by the bottom surface 31 and the inner side surface 32 of the cavity 30 are processed into an R shape. In addition, inner corners 37 on the inner circumferential side at both ends in the circumferential direction formed by the inner circumferential surface 11 of the convex portion 12 and the inner side surface 32 of the cavity 30 of the cavity 30 are formed in a right angle.

  The green compact molding procedure by the mold apparatus 2 of the second embodiment is the same as that of the first embodiment. After the mold is set as described above, the lower punch 50 is inserted into the cavity 30 and the cavity 30 is inserted. The green compact is formed through steps such as supply of the raw material powder P to the cavities, insertion of the upper punch 40 into the cavity 30 and compression of the raw material powder P by the upper and lower punches 40 and 50.

  FIG. 14 shows an end face of the green compact P2 formed by the mold apparatus 2. As is clear from a comparison between FIG. 14 and FIG. 13 showing the cavity 30, the green compact P2 has an outer periphery. The surface 1 a is formed by the bottom surface 31 of the cavity 30 on the die 10 side, the inner peripheral surface 1 b is formed by the outer peripheral surface 21 of the core rod 20, and both side surfaces 1 c are formed by the inner side surface 32 of the cavity 30. In addition, the outer corners 1e on the outer peripheral side at both ends in the circumferential direction are formed in an R shape in which the R-shaped inner corner 36 of the cavity 30 is transferred and chamfered at a right angle, and the outer corner 1d on the inner peripheral side. Is formed in a right-angled shape by transferring a right-angled inner corner 37 formed by the inner surface 32 of the cavity 30 on the die 10 side and the outer peripheral surface 21 of the core rod 20.

  According to the mold apparatus of the second embodiment, the outer corner 1d on the inner peripheral side at both ends in the circumferential direction of the green compact P1 has the inner surface 32 of the cavity 30 and the outer peripheral surface 21 of the core rod 20 as described above. The right-angled inner corner portion 37 formed in the above is transferred to form a right angle. That is, the inner corner 1d on the inner peripheral side of the cavity 30 is formed in a right angle by the dice 10 and the core rod 20 to be divided, and from the inner corner 1d, as shown in FIG. The joint boundary surface 62 between the outer peripheral surface 21 and the inner peripheral surface 11 of the convex portion 12 of the die 10 extends outward in the circumferential direction.

  For this reason, when a stress is applied to the inner corner portion 37 when the raw material powder P is compression-molded by the upper and lower punches 40, 50, the stress leaks from the inner corner portion 37 to the joining boundary surface 62, and the inner No stress concentration on the corner 37 occurs. As a result, the occurrence of cracks starting from the inner corner 37 is prevented. On the other hand, the inner corner 36 on the outer peripheral side of the cavity 30 is formed only by the die 10, but is formed in an R shape, so that stress concentration is less likely to occur. From these facts, as in the first embodiment, even if the raw material powder P is of high hardness such as magnetic powder, it is possible to accurately form a green compact of a desired shape by compressing at high pressure. Such an effect is produced.

  In the second embodiment, the first and second modifications of the first embodiment can be applied. That is, when the first modification is applied, instead of the lower punch 50, the lower end portion of the cavity 30 on the die 10 side is filled with the lower end portion and integrated with the convex portion 12. 11, a closed portion having an inner peripheral surface of the same diameter is formed, and the upper end surface of this closed portion is defined as a stepped portion. The raw material powder is sandwiched between the stepped portion and the upper punch 40 and compressed in the axial direction. Moreover, when applying the modified example 2, it can implement by setting it as the structure divided | segmented into the step part side containing the step part, and the main body side containing the cavity 30 and the convex part 12. FIG.

(5) Third Embodiment Next, a mold apparatus according to a third embodiment of the present invention will be described with reference to FIGS.
The mold apparatus 3 according to the third embodiment includes the die 10, the core rod 20, and the upper and lower punches 40 and 50, as in the first and second embodiments, but the cavity 30 is formed in the die 10 and the core rod 20. The intermediate mold 70 for forming the cavity 30 is provided as a separate member.

  As shown in FIGS. 15 and 16, the inner peripheral surface 11 of the die 10 and the outer peripheral surface 21 of the core rod 20 are formed in a simple cylindrical shape, and the core rod 20 is inserted concentrically into the hollow portion 15 of the die 10. Between the outer peripheral surface 21 and the inner peripheral surface 11 of the die 10, a gap 19 of a constant distance is formed over the entire periphery. This gap 19 is set to a dimension equivalent to the thickness of the curved plate-like component to be obtained. The intermediate mold 70 is slidably inserted into a plurality of locations (in this case, two locations) equally divided by the circumference of the gap 19.

  The intermediate die 70 has a shape and size similar to a curved plate-like component, and when inserted into the gap 19, the intermediate die 70 is surrounded by the side surface 71 of the intermediate die 70, the inner peripheral surface 11 of the die 10, and the outer peripheral surface 21 of the core rod 20. A cavity 30 is formed. The cavity 30 is formed in a shape corresponding to the curved plate-like component, and the upper and lower punches 40 and 50 are slidably inserted into the cavity 30.

  As shown in FIG. 17, inner corners 38 on the inner circumferential side of both ends in the circumferential direction formed by the outer circumferential surface 21 of the core rod 20 and the side surfaces 71 of the intermediate mold 70, and the inner circumferential surface 11 of the die 10. The inner corner portions 39 on the outer peripheral side at both ends in the circumferential direction formed by the intermediate mold 70 and the side surface 71 of the intermediate mold 70 are all formed in a right angle shape.

  In order to mold the green compact by the mold apparatus 3 of the third embodiment, first, as shown in FIG. 16A, the core rod 20 is inserted into the hollow portion 15 of the die 10, and the die 10, the core rod 20, The intermediate mold 70 is inserted into the gap 19 between the two, and the mold is set. Then, the upper end portion of the lower punch 50 is inserted into the cavity 30 defined by the die 10, the core rod 20, and the intermediate mold 70 from the lower side, and then the raw material powder P is supplied to the cavity 30. Next, as shown in FIG. 16 (b), the upper punch 40 is inserted into the cavity 30 from the upper side, the lower punch 50 is raised as appropriate, and the raw material powder P is sandwiched between the upper and lower punches 40, 50 to be predetermined in the axial direction. Compress with pressure.

  FIG. 18 shows the end face of the formed green compact P3. As is apparent from comparing FIG. 18 with FIG. 17 showing the cavity 30, the outer peripheral surface 1a of the green compact P3 has a die 10 as shown in FIG. The inner peripheral surface 1 b is formed by the outer peripheral surface 21 of the core rod 20, and both side surfaces 1 c are formed by the side surfaces 71 of the intermediate mold 70. In addition, the inner corners 1d and 1e on the inner peripheral side and the outer peripheral side at both ends in the circumferential direction are formed in a right angle by transferring the right inner corners 38 and 39 of the cavity 30, respectively.

  According to the mold apparatus 3 of the third embodiment, the outer corners 1d and 1e on the inner peripheral side and the outer peripheral side at both ends in the circumferential direction of the green compact P3 are respectively formed at right angles to the cavity 30. Formed by corners 38,39. As shown in FIG. 17, of the inner corner portions 38 and 39 of the cavity 30, the inner corner portion 38 on the inner peripheral side is formed by the outer peripheral surface 21 of the core rod 20 and the side surface 71 of the intermediate mold 70. From the portion 38, a joint boundary surface 63 between the outer peripheral surface 21 of the core rod 20 and the inner peripheral surface 72 of the intermediate die 70 extends outward along the circumferential direction. On the other hand, the inner corner portion 39 on the outer peripheral side is formed by the inner peripheral surface 11 of the die 10 and the side surface 71 of the intermediate die 70, and from the inner corner portion 39, the inner peripheral surface 11 of the die 10 and the intermediate die 70. A joint boundary surface 64 with the outer peripheral surface 73 extends outward along the circumferential direction.

  For this reason, when stress is applied to the inner corner portions 38 and 39 when the raw material powder P is compression-molded by the upper and lower punches 40 and 50, the stress is applied to the joint boundary surface at the inner corner portion 38 on the inner peripheral side. 63 leaks to the joint boundary surface 64 at the inner corner 39 on the outer peripheral side. Therefore, stress concentration on the inner corners 38 and 39 does not occur, and cracks starting from the inner corners 38 and 39 are prevented. As a result, as in the first and second embodiments, even if the raw material powder P is of high hardness such as magnetic powder, it is possible to accurately form a green compact of a desired shape by compressing at high pressure. The effect that it is possible is produced.

  In each of the above embodiments, since the outer peripheral side and the inner peripheral side of the cavity 30 are concentric, the green compact of the obtained curved plate-like part has a uniform thickness. The curved plate-like component is not limited to having a uniform thickness. For example, as shown in FIG. 19, a configuration in which the diameter of the inner peripheral side 30 c is larger than the outer peripheral side 30 b of the cavity 30 and is not concentric is also included. In this case, the curved plate-like component molded in the cavity 30 in FIG. 19A has a cross-sectional shape that gradually decreases in thickness from the center in the circumferential direction toward both ends. In the cavity 30 in FIG. The curved plate-like component to be molded has a cross-sectional shape that gradually decreases in thickness from one end in the circumferential direction toward the other end. The number of cavities 30 is arbitrary, and at least one cavity is formed.

DESCRIPTION OF SYMBOLS 1, 2, 3 ... Mold apparatus 10 ... Dice 11 ... Inner peripheral surface of die 12 ... Die convex part 15 ... Die hollow part 19 ... Gap 20 ... Core rod 21 ... Outer peripheral surface of core rod 22 ... Convex part of core rod 24 ... Step portion 26 ... Core rod body side 28 ... Core rod step side 30 ... Cavity 31 ... Cavity bottom surface 33-39 ... Cavity inner corner 40 ... Upper punch 50 ... Lower punch 60-64 ... Junction interface 70 ... Intermediate mold 100 ... Curved plate-shaped part P ... Raw material powder P1, P2, P3 ... Green compact

Claims (6)

A mold apparatus for molding a green compact of a curved plate-shaped part,
A die having a hollow portion formed by a cylindrical inner peripheral surface;
A core rod having a cylindrical outer peripheral surface and slidably inserted into the hollow portion of the die;
A punch having a shape corresponding to the curved plate-like component;
With
A cavity having a shape corresponding to the curved plate-shaped component is formed in one of the inner peripheral surface of the die and the outer peripheral surface of the core rod, and a space between the cavities in the circumferential direction is formed. A curved plate-like convex part that closes a part between the die and the core rod to form the inner surface of the cavity is disposed,
In the mold set state in which the core rod is inserted into the hollow portion of the die, the cavity is partitioned by the die and the core rod,
The green compact molding die apparatus for a curved plate-shaped part, wherein the raw material powder supplied to the cavity is compressed in the axial direction by the punch to mold the green compact of the curved plate-shaped part.   2. The green compact mold apparatus for a curved plate part according to claim 1, wherein an inner corner formed by the bottom surface and the inner side surface of the cavity is formed in an R shape.   The cavity in the mold set state is opened on one end side in the axial direction, the other end side is closed by a step formed on the die or the core rod, and the punch is inserted into the cavity from the opening on one end side. The green compact mold apparatus for a curved plate-like part according to claim 1 or 2, wherein:   4. The green compact mold apparatus for a curved plate part according to claim 3, wherein an inner corner portion of the step portion is formed in an R shape.   The die or the core rod in which the step portion is formed is divided in an axial direction into a main body side including the cavity and a step portion side including the step portion, with the step portion serving as a boundary. The green compact mold apparatus for curved plate-like parts according to claim 3. A mold apparatus for molding a green compact of a curved plate-shaped part,
A die having a hollow portion formed by a cylindrical inner peripheral surface;
A core rod that has a cylindrical outer peripheral surface, and is inserted into the hollow portion of the die in a state where a gap is formed between the inner peripheral surface of the die,
A curved plate-shaped intermediate mold that is slidably inserted into the gap and forms a cavity having a shape corresponding to the curved plate-shaped component between the circumferential directions;
A punch having a shape corresponding to the curved plate-like component;
With
The core rod is inserted into the hollow portion of the die, and the die is set in a state where the intermediate die is inserted into the gap formed between the inner peripheral surface of the die and the outer peripheral surface of the core rod. The cavity is defined by an inner peripheral surface, an outer peripheral surface of the core rod, and the intermediate mold,
The green compact molding die apparatus for a curved plate-shaped part, wherein the raw material powder supplied to the cavity is compressed in the axial direction by the punch to mold the green compact of the curved plate-shaped part.

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