Molding die and molding method

Abstract

A molding die includes a first die having a through-hole; a second die inserted into the through-hole and configured to be movable relative to the first die; and first and second punches configured to be insertable into the through-hole, wherein an undercut molding part is provided on the second die, and a molding target is compression-molded in a cavity surrounded by inner side walls of the through-hole, the second die, the first punch, and the second punch.

Claims

1. A molding die comprising: a first die having a through-hole; a second die inserted into the through-hole from a first direction of the through-hole and configured to be movable relative to the first die in an inserting/releasing direction; a first punch configured to be insertable into the through-hole from the first direction of the through-hole, a second punch configured to be insertable into the through-hole from a second direction of the through-hole opposite to the first direction; a third punch configured to be insertable into the through-hole from the second direction of the through-hole; and a pressurizing mechanism including a first pressing part that independently moves only the first punch in the inserting/releasing direction, and a second pressing part that independently moves only the second die in the inserting/releasing direction, said pressurizing mechanism being configured to move the first punch and the second die simultaneously in compressing a molding target, wherein the molding target is compression-molded in a cavity surrounded by inner side walls of the through-hole, the second die, the first punch, and the second punch, the second die comes into contact with an outer circumferential surface of the first punch, and is configured to be slidable relative to the first punch in the inserting/releasing direction, the second die is extended in the second direction farther than the first punch in the cavity, an undercut molding part having a corrugation that extends in a direction intersecting the inserting/releasing direction is formed in a side surface of the second die configuring one portion of the cavity, the first punch and the second die are simultaneously moved in compressing the molding target, the third punch comes into contact with an outer circumferential surface of the second punch, and is configured to be slidable relative to the second punch in the inserting/releasing direction, and an end of the third punch in the second direction and an end of the second die in the first direction are arranged to face each other.

2. The molding die according to claim 1, wherein the second die is inserted into the through-hole such that a part of the second die comes into contact with the inner side walls of the through-hole.

3. The molding die according to claim 1, further comprising a third die inserted into the through-hole such that a part of the third die comes into contact with the inner side walls of the through-hole, and configured to be movable relative to the first and second dies.

4. The molding die according to claim 1, further comprising a core rod configured to be insertable into the cavity.

5. The molding die according to claim 1, wherein the molding target is a powder.

6. A molding method using the molding die according to claim 1, the molding method at least comprising: an introducing process of inserting the second punch and the third punch from the second direction of the through-hole and introducing the molding target into the through-hole; an inserting process of simultaneously inserting the first punch and the second die from the first direction of the through-hole; an operating process of operating the pressurizing mechanism to simultaneously move the first punch and the second die; a compacting process of moving the first punch and the second punch toward each other, while contacting the third punch with the second die and compression-molding the molding target in the cavity, and molding a molding; and an ejecting process of ejecting the molding from the molding die.

7. The molding method according to claim 6, wherein the ejecting process is a process of pulling the first punch, the second die, and the molding out of the through-hole, moving the second die and the molding relative to the first punch to remove the molding from the first punch, and moving the molding relative to the second die in a direction intersecting the inserting/releasing direction to remove the molding from the second die.

8. A molding die comprising: a first die having a through-hole; a second die inserted into the through-hole from a second direction of the through-hole and configured to be movable relative to the first die in an inserting/releasing direction; and a first punch configured to be insertable into the through-hole from a first direction of the through-hole opposite to the second direction; a second punch configured to be insertable into the through-hole from the second direction; and a pressurizing mechanism which brings the first punch into contact with the second die while moving each other, said pressuring mechanism including a first pressing part that independently moves only the first punch in the inserting/releasing direction, and a second pressing part that independently moves only the second die in the inserting/releasing direction, wherein a molding target is compression-molded in a cavity surrounded by inner side walls of the through-hole, the second die, the first punch, and the second punch, the second die is extended in the second direction farther than the second punch inside the cavity, an undercut molding part having a corrugation that extends in a direction intersecting the inserting/releasing direction is formed in a side surface of the second die configuring one portion of the cavity, and an end of the first punch in the first direction comes into contact with a front end of the second die in the second direction.

9. A molding method using the molding die according to claim 8, the molding method at least comprising: an introducing process of inserting the second punch and the second die from the second direction of the through-hole and introducing the molding target into the through-hole; an inserting process of inserting the first punch from the first direction of the through-hole; a compacting process of moving the first punch and the second punch toward each other, compression-molding the molding target in the cavity, and molding a molding; and an ejecting process of ejecting the molding from the molding die.

10. A molding die comprising: a first die having a through-hole; a second die inserted into the through-hole from a first direction of the through-hole and configured to be movable relative to the first die in an inserting/releasing direction; a first punch configured to be insertable into the through-hole from the first direction of the through-hole, a second punch configured to be insertable into the through-hole from a second direction of the through-hole opposite to the first direction; and a pressurizing mechanism including a first pressing part that independently moves only the first punch in the inserting/releasing direction toward the second direction, and a second pressing part that independently moves only the second die in the inserting/releasing direction toward the second direction, wherein a molding target is compression-molded in a cavity surrounded by inner side walls of the through-hole, the second die, the first punch, and the second punch, an undercut molding part having a corrugation that extends in a direction intersecting the inserting/releasing direction is formed in a side surface of the second die configuring one portion of the cavity, and the first punch and the second die are simultaneously moved in compressing the molding target.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a sectional view showing a molding die according to an embodiment of the present invention.

(2) FIG. 2 is an enlarged sectional view of main parts when a second die of the molding die is viewed from above.

(3) FIG. 3 is an exterior perspective view showing an example of a molding.

(4) FIG. 4 is a top view showing examples of a shape of an undercut molding part.

(5) FIG. 5 is a sectional view showing a molding method according to a first embodiment of the present invention in a step-by-step manner.

(6) FIG. 6 is a sectional view showing the molding method according to the first embodiment of the present invention in a step-by-step manner.

(7) FIG. 7 is a sectional view showing a molding method according to a second embodiment of the present invention in a step-by-step manner.

(8) FIG. 8 is a sectional view showing the molding method according to the second embodiment of the present invention in a step-by-step manner.

(9) FIG. 9 is an upper sectional view showing a molding die according to another embodiment of the present invention.

(10) FIG. 10 is an upper sectional view showing a molding die according to another embodiment of the present invention, and is an exterior perspective view showing a molding.

(11) FIG. 11 is an upper sectional view showing a molding die according to another embodiment of the present invention, and is an exterior perspective view showing a molding.

DETAILED DESCRIPTION THE INVENTION

(12) Hereinafter, a molding die and a molding method that are an embodiment to which the present invention is applied will be described with reference to the drawings. The embodiments shown below will be specifically described so that the gist of the invention can be better understood, and do not limit the present invention unless indicated otherwise. In addition, the drawings used for the following description may show portions that are main parts in an enlarged scale for convenience in order to facilitate understanding of features of the present invention, and dimensional ratios of the components are not necessarily the same as the actual dimensional ratios.

(13) FIG. 1 is a sectional view showing a molding die according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view of main parts when a second die of the molding die is viewed from above.

(14) A molding die 10 is a die that uses, for instance, a powder as an example of a molding target and forms a green compact as an example of a molding using compression molding.

(15) The molding die 10 includes a first die 11, a second die 12 that enables relative movement relative to the first die 11, a first punch 13, a second punch 14, a third punch 15, and a core rod 16.

(16) The first die 11 has, for instance, an approximately cylindrical contour, and is formed with a through-hole 22 that passes from first opening 11a to the second opening 11b. In the present embodiment, the through-hole 22 forms a cuboidal space surrounded by four inner side walls 22a to 22d.

(17) The second die 12 has, for instance, a plate shape, and is formed with an undercut molding part 32 having a corrugation 31 that extends in a direction intersecting (or perpendicular to) an inserting/releasing direction Y. In the present embodiment, the corrugation 31 formed at the undercut molding part 32 is made up of three projections that protrude in a horizontal direction and have a semicircular cross section. The inserting/releasing direction Y in the present embodiment is a direction in which the first punch 13, the second punch 14, and the second die 12 are inserted into and released from the through-hole 22 of the first die 11.

(18) This undercut molding part 32 gives an undercut shape to the green compact in a molding method to be described below.

(19) The second die 12 is inserted into the through-hole 22 at the time of molding such that an outer surface 12a of the second die 12 comes into contact with the inner side wall 22a of the through-hole 22 of the first die 11.

(20) The second die 12 comes into contact with a circumferential surface 13b of the first punch 13 to be described below, and is formed to be slidable relative to the first punch 13 in the inserting/releasing direction Y.

(21) The first punch 13 is inserted into a part of the through-hole 22 of the first die 11 at the time of molding, and compacts the powder, which is an example of the molding target, in the inserting/releasing direction Y. The first punch 13 has, for instance, an approximately cuboidal contour, and has a through-hole 13a formed therein. A part of the core rod 16 to be described below can be inserted into and released from the through-hole 13a.

(22) The second punch 14 is formed to face the first punch 13 via the through-hole 22 of the first die 11. The second punch 14 is inserted into the through-hole 22 of the first die 11 at the time of molding, and compacts the powder, which is an example of the molding target, in the inserting/releasing direction Y to put the powder between the first punch 13 and the second punch 14. The second punch 14 has, for instance, an approximately cuboidal contour, and has a through-hole 14a formed therein. A part of the core rod 16 to be described below can be inserted into and released from the through-hole 14a.

(23) The third punch 15 is an approximately plate-like member formed to face an end of the second die 12. The third punch 15 is inserted into the through-hole 22 such that an outer surface 15a of the third punch 15 comes into contact with the inner side wall 22a of the through-hole 22 of the first die 11 at the time of molding.

(24) The third punch 15 comes into contact with a circumferential surface 14b of the second punch 14, and is formed to be slidable relative to the second punch 14 in the inserting/releasing direction Y.

(25) A space surrounded by the inner side walls 22b, 22c and 22d of the through-hole 22 of the first die 11, the undercut molding part 32 of the second die 12, an end face of the first punch 13, and an end face of the second punch 14 becomes a cavity P. The green compact is molded in this cavity P by compression-molding the powder W that is the molding target.

(26) The core rod 16 is, for instance, an approximately plate-like elongated member, and is disposed to pass through the cavity P from the through-hole 14a of the second punch 14 toward the through-hole 13a of the first punch 13 in an insertable/releasable manner. The core rod 16 configured in this way forms a through-hole having a rectangular cross section with respect to the green compact formed in the cavity P.

(27) In this molding die 10, at the time of molding, the first punch 13 is moved toward the second punch 14 by a pressurizing mechanism 50, and reduces the cavity P in the inserting/releasing direction Y to compact the powder W that is the molding target. The pressurizing mechanism 50 has a first pressing part 50a that can independently move only the first punch 13 up and down, and a second pressing part 50b that can independently move only the second die 12 up and down.

(28) FIG. 3 is an exterior perspective view showing an example of the green compact (the molding) formed using the molding die 10 having this constitution. The green compact 40 is an approximate cuboid, and includes a through-hole 41 that is formed in the center of the green compact 40 by the core rod 16 (see FIGS. 1 and 2) and has a rectangular cross section. Three grooves 33 that are molded by the corrugation 31 of the undercut molding part 32 are provided on one surface of the green compact 40 (see FIGS. 1 and 2) and have an approximately semicircular cross section. These grooves 33 have an undercut shape that is a corrugation extending in the direction intersecting (or perpendicular to) the inserting/releasing direction Y when the green compact 40 is molded.

(29) The undercut shape formed on the green compact (the molding) 40 has the plurality of grooves 33 that extend in one direction in the present embodiment, but the undercut shape is not limited thereto.

(30) Several specific examples of the undercut shape formed at the green compact (the molding) are shown in FIG. 4.

(31) For example, a lattice-like undercut shape 102 in which a plurality of grooves are formed in two directions perpendicular to each other is molded on a green compact (a molding) 101 of FIG. 4(a). An undercut shape 104 in which a plurality of hemispherical dimples are arranged and formed is molded on a green compact (a molding) 103 of FIG. 4(b). An undercut shape 106 in which a plurality of grooves extending to be bent in a chevron shape are arranged and formed is molded on a green compact (a molding) 105 of FIG. 4(c).

(32) Each of inverted shapes of the undercut shapes 102, 104 and 106 of these embodiments is provided on the undercut molding part 32 of the second die 12 of the molding die 10, so that the green compacts (the moldings) 101, 103 and 105 shown in FIGS. 4(a) to 4(c) can be obtained.

(33) In the embodiment of the molding die of the present invention which is described above, the example in which the molding die from which the green compact that is an example of the molding is obtained using the powder raw material as the molding target is presented, but the molding target is not limited to the powder. For example, a coarsely formed solid material may also be applied in the same way to so-called sizing of using the solid material as the molding target, introducing the solid material into the cavity of the molding die of the present invention, and molding the solid material in a predetermined shape.

(34) A variety of forms such as an aggregated form, a granular form, or the like may be used as the molding target in addition to the powder or the coarsely formed solid material.

Molding Method: First Embodiment

(35) A molding method of the present invention which uses the molding die having the constitution described above will be described. FIGS. 5 and 6 are sectional views showing a molding method of a first embodiment of the present invention in a step-by-step manner.

(36) When the green compact 40 having the undercut shape, for instance, as shown in FIG. 3, is molded according to the molding method of the first embodiment of the present invention, the second punch 14 into which the core rod 16 is inserted and the third punch 15 are first inserted into the through-hole 22 from the second opening 11b of the first die 11 as shown in FIG. 5(a) (an inserting process). In this case, the second die 12 and the first punch 13 are located at a position at which they have retreated above the first die 11.

(37) Next, a powder W used as a molding target is filled (introduced) in the through-hole 22 of the first die 11 (an introducing process). The powder W to be filled includes, for instance, an iron or copper powder that is mainly composed of a metal, a mixed powder thereof, or the like.

(38) Next, as shown in FIG. 5(b), the pressurizing mechanism 50 is operated to lower the first punch 13 and the second die 12, and simultaneously inserts the first punch 13 and the second die 12 into the through-hole 22 from the first opening 11a of the first die 11 (an inserting process). Meanwhile, the second die 12 is lowered to push down the third punch 15, and comes into contact with the powder W with which the undercut molding part 32 of the second die 12 is filled. Thereby, a cavity P is defined in the through-hole 22 by the inner side walls 22b, 22c and 22d of the through-hole 22, the undercut molding part 32 of the second die 12, the entire circumferential surface of the core rod 16, the end face of the first punch 13, and the end face of the second punch 14.

(39) In this way, in the state in which the cavity P is formed in the through-hole 22, the pressurizing mechanism 50 further pushes down the first punch 13 to compact the powder W (a compacting process). Due to the compacting process, the powder W is compacted in the cavity P, and a green compact (a molding) 40 modeled after an internal shape of the cavity P is molded. A through-hole 41 that is modeled after the core rod 16 and has a rectangular cross section is also molded at the same time.

(40) During this compaction of the powder W, the compacted powder is pressed to the undercut molding part 32 of the second die 12, and the corrugation 31 protruding in the direction intersecting (or perpendicular to) the inserting/releasing direction Y is transferred.

(41) Three grooves 33 formed in an undercut shape having an approximately semicircular cross section are molded in the green compact (the molding) 40.

(42) As shown in FIG. 5(c), after the molding of the green compact (the molding) 40 is completed, the second punch 14 and the third punch 15 are raised while pressing down the green compact 40 with the first punch 13, and the first punch 13, the second die 12, and the green compact 40 are pulled out of the through-hole 22 (an ejecting process).

(43) In this case, the second die 12 having the undercut molding part 32 by which the grooves 33 of the undercut shape are formed in the green compact 40 is pushed out of the through-hole 22 by pushing up the third punch 15 with the corrugation 31 brought into close contact with the grooves 33 of the green compact 40 (see FIG. 6(a)). The core rod 16 is fixed at the same position as the first die 11.

(44) As shown in FIG. 6(b), the pressurizing mechanism 50 is moved upward in a state in which the green compact 40 is held on the first punch 13 and the second die 12.

(45) Afterward, only the second pressing part 50b of the pressurizing mechanism 50 which is in contact with the second die 12 is slightly lowered, and thereby the second die 12 and the green compact 40 are moved relative to the first punch 13 to release an upper portion of the green compact 40 from a lower end face of the first punch 13 (see FIG. 6(c)).

(46) Then, the green compact 40 is moved relative to the second die 12 in the direction intersecting (or perpendicular to) the inserting/releasing direction Y, and is removed from the second die 12. Thereby, the green compact (the molding) 40 in which the grooves 33 of the undercut shape as shown in FIG. 3 are formed and the through-hole 41 is also formed at the same time can be obtained.

(47) As described above, according to the molding die and molding method of the present invention, the highly precise undercut shape (the grooves 33 in the present embodiment) can be easily molded for the green compact (the molding) 40 by simply inserting the second die 12 having the undercut molding part 32 into the through-hole 22 of the first die 11 and performing molding.

(48) The green compact (the molding) 40 having this undercut shape is ejected from the through-hole 22 of the first die 11 along with the first punch 13 and the second die 12, so that the green compact (the molding) 40 can be released without damaging the undercut shape.

(49) Thereby, as in the related art, the green compact (the molding) 40 having this undercut shape can be molded with ease and with high precision without using, for instance, the die having dividable dies.

(50) In the molding die and molding method of the aforementioned embodiment, only the second die that can be moved relative to the first die is used as the die having the undercut molding part. However, a molding having a more complicated undercut shape may be molded by inserting the plurality of dies having the undercut molding part into the through-hole of the first die.

Molding Method: Second Embodiment

(51) A molding method of a second embodiment of the present invention is an example in which the second die 12 disposed at the upper side in the first embodiment is disposed at a lower side.

(52) FIGS. 7 and 8 are sectional views showing a molding method of a second embodiment of the present invention in a step-by-step manner.

(53) Components that are the same as those of the molding method of the first embodiment shown in FIGS. 5 and 6 will be given the same reference signs, and duplicate descriptions will be omitted.

(54) When the green compact 40 having the undercut shape, for instance, as shown in FIG. 3, is molded by the molding method of the second embodiment of the present invention, a second punch 94 into which the core rod 16 is inserted and the second die 12 are first inserted into the through-hole 22 from the second opening 11b of the first die 11 as shown in FIG. 7(a) (an inserting process). In this case, a first punch 93 is located at a position at which it has retreated above the first die 11.

(55) Next, a powder W used as a molding target is filled (introduced) in the through-hole 22 of the first die 11 (an introducing process). The powder W to be filled includes, for instance, an iron or copper powder that is mainly composed of a metal, a mixed powder thereof, or the like.

(56) Next, as shown in FIG. 7(b), the pressurizing mechanism 50 is operated to lower the first punch 93, and inserts the first punch 93 into the through-hole 22 from the first opening 11a of the first die 11 (an inserting process). The filled powder W is pressed to the undercut molding part 32 of the second die 12. Thereby, a cavity P is defined in the through-hole 22 by the inner side walls 22b, 22c and 22d of the through-hole 22, the undercut molding part 32 of the second die 12, the entire circumferential surface of the core rod 16, an end face of the second punch 94, and an end face of the first punch 93.

(57) In this way, in the state in which the cavity P is formed in the through-hole 22, the pressurizing mechanism 50 further pushes down the first punch 93 to compact the powder W (a compacting process). Due to the compacting process, the powder W is compacted in the cavity P, and a green compact (a molding) 40 modeled after an internal shape of the cavity P is molded. A through-hole 41 that is modeled after the core rod 16 and has a rectangular cross section is also molded at the same time.

(58) During this compaction of thee powder W, the compacted powder is pressed to the undercut molding part 32 of the second die 12, and the corrugation 31 protruding in the direction intersecting (or perpendicular to) the inserting/releasing direction Y is transferred.

(59) Three grooves 33 formed in an undercut shape having an approximately semicircular cross section are molded in the green compact (the molding) 40.

(60) As shown in FIG. 7(c), after the molding of the green compact (the molding) 40 is completed, the first punch 93 and the second die 12 are raised while the green compact 40 is supported with the second punch 94, and the second punch 94, the undercut molding part 32 of the second die 12, and the green compact 40 are pulled out of the through-hole 22 (an ejecting process). The second die 12 having the undercut molding part 32 by which the grooves 33 of the undercut shape are formed in the green compact 40 is pushed out of the through-hole 22 with the corrugation 31 brought into close contact with the grooves 33 of the green compact 40 (see FIG. 8(a)). The core rod 16 is fixed at the same position as the first die 11.

(61) As shown in FIG. 8(b), the first punch 93 retreats upward.

(62) Afterward, the green compact (the molding) 40 is moved in a transverse direction, and is released from an upper end face of the second punch 94 and the undercut molding part 32 of the second die 12 (see FIG. 8(c)).

(63) As described above, according to the molding method of the second embodiment of the present invention, the highly precise undercut shape (the grooves 33 in the present embodiment) can be easily molded for the green compact (the molding) 40 by simply inserting the second die 12 having the undercut molding part 32 into the through-hole 22 of the first die 11 and performing molding.

(64) The green compact (the molding) 40 having this undercut shape is ejected from the through-hole 22 of the first die 11 along with the first punch 93 and the second die 12, so that the green compact (the molding) 40 can be released without damaging the undercut shape.

(65) Thereby, as in the related art, the green compact (the molding) 40 having this undercut shape can be molded with ease and with high precision without using, for instance, the die having dividable dies.

(66) FIG. 9 is an upper sectional view showing another embodiment of the molding die of the present invention. Components that are the same as those of the first embodiment shown in FIG. 1 will be given the same reference signs, and duplicate descriptions will be omitted.

(67) A molding die 60 of another embodiment shown in FIG. 9 includes a second die 12 and a third die 62 that can be inserted into a through-hole 22 of a first die 11. Undercut molding parts 32 and 63 are formed at the second die 12 and the third die 62. Thereby, a cavity P surrounded by an inner side wall of the first die 11, the second die 12, the third die 62, the end face of a first punch, and the end face of a second punch is formed in the through-hole 22.

(68) According to the molding die 60 having this constitution, the undercut shapes can be formed on two sides of a cuboidal molding 65.

(69) FIG. 10(a) is an upper sectional view showing another embodiment of the molding die of the present invention. FIG. 10(b) is an exterior perspective view showing an example of a molding obtained by the molding die of the present embodiment. Components that are the same as those of the first embodiment shown in FIG. 1 will be given the same reference signs, and duplicate descriptions will be omitted.

(70) A molding die 70 of another embodiment shown in FIG. 10 has an approximately cylindrical through-hole 71 formed in a first die 11, and includes a second die 72 that can be inserted into the through-hole 71. The second die 72 is a plate-like member that is in contact with an inner side wall 71a of the through-hole 71 formed in the first die 11 and is curved in a semicircular shape of 180. An undercut molding part 73 is formed on an inner circumferential surface 72a of the second die 72, has a semicircular cross section, and extends in one direction of the inner circumferential surface 72a.

(71) Thereby, a cavity P surrounded by the inner side wall 71a of the first die 11, the inner circumferential surface 72a of the second die 72 on which the undercut molding part 73 is formed, the end face of a first punch, and the end face of a second punch is formed in the through-hole 71. A core rod 16 having a circular cross section passes in the vicinity of the center of the cavity P.

(72) After a molding 75 is molded using the molding die 70 having this constitution, if the second die 72 is extracted from the first die 11 in an inserting/releasing direction Y along with the molding 75, and is further moved in a horizontal direction L, then the molding 75 is released from the second die 72. As shown in FIG. 10(b), the molding 75 including an undercut shape 76 made up of a groove having a semicircular cross section only in an area of half of a circumferential surface 75a of the cylindrical molding 75 and having a through-hole 77 formed in a central portion of the cylindrical molding 75 can be molded.

(73) FIG. 11(a) is an upper sectional view showing another embodiment of the molding die of the present invention. FIG. 11(b) is an exterior perspective view showing an example of a molding obtained by the molding die of the present embodiment. Components that are the same as those of the first embodiment shown in FIG. 1 will be given the same reference sign, and duplicate descriptions will be omitted.

(74) A molding die 80 of another embodiment shown in FIG. 11 has an approximately cuboidal through-hole 81 formed in a first die 11, and includes a second die 82 that can be inserted into the through-hole 81. The second die 82 is a plate-like member that is in contact with three inner side walls 81a to 81c among four inner side walls 81a to 81d of the through-hole 81 formed in the first die 11 and is formed in a U shape. An undercut molding part 83, which has an approximately trapezoidal cross section and extends in one direction of each of inner side walls 82a to 82c, is formed at the second die 82.

(75) Thereby, a cavity P is formed in the through-hole 81 by the inner side wall 81d of the first die 11, the inner side walls 82a to 82c of the second die 82 at which the undercut molding part 83 is formed, an end face of a first punch, and an end face of a second punch. A core rod 16 having a circular cross section passes in the vicinity of the center of the cavity P.

(76) After a molding 85 is molded using the molding die 80 having this constitution, if the second die 82 is extracted from the first die 11 in an inserting/releasing direction Y along with the molding 85, and the second die 82 is further moved in a horizontal direction L, then the molding 85 is released from the second die 82. As shown in FIG. 11(b), the molding 85 including undercut shapes 86, each of which is made up of a groove having a trapezoidal cross section, at three sides 85a to 85c among four sides 85a to 85d of the cuboidal molding 85 and having a through-hole 87 formed in a central portion of the cuboidal molding 85 can be molded.

(77) In the embodiments of the molding method of the present invention described above, the example in which the green compact that is an example of the molding is obtained using the powder raw material as the molding target is presented, but the molding target is not limited to the powder. For example, a coarsely formed solid material may also be applied in the same way to so-called sizing of using the solid material as the molding target, introducing the solid material into the cavity of the molding die of the present invention, and molding the solid material in a predetermined shape.

(78) A variety of forms such as an aggregated form, a granular form, or the like may be used as the molding target in addition to the powder or the coarsely formed solid material.

(79) While several embodiments of the present invention have been described, these embodiments are presented by way of example, and are not intended to limit the scope of the invention. These embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications are possible without departing from the spirit and scope of the present invention. These embodiments or modifications thereof are included in the scope or the spirit of the invention, and are included in the invention described in the claims and the scope equivalent to the claims.

INDUSTRIAL APPLICABILITY

(80) According to the molding die and molding method of the present invention, a molding including an undercut shape can be molded with high precision and with ease.

REFERENCE SIGNS LIST

(81) 10, 70, 80 Molding die 11 First die 12, 72, 82 Second die 13, 93 First punch 14, 94 Second punch 15 Third punch 16 Core rod 22, 71, 81 Through-hole 22a to 22d, 71a, 81a to 81d Inner side wall 32, 63, 73, 83 Undercut molding part 40, 65, 75, 85 Green compact (molding) 62 Third die P Cavity