TWI592232B - Metal powder injection molding - Google Patents

Description

Forming mold for metal powder injection molding

The present invention relates to a molding die for metal powder injection molding.

In recent years, as a method of manufacturing a metal sintered body having a complicated shape, a metal injection molding method (MIM) has been popularized. The metal powder injection molding method is produced by molding a kneaded material of a metal powder and an organic binder into a cavity of a molding die, and degreasing and calcining the obtained molded body to produce a desired metal sintered body. The method. According to this method, since the metal sintered body having a shape close to the final shape can be produced, the secondary processing can be omitted, or the amount of processing can be reduced, and the simplification of the manufacturing steps and the reduction of the manufacturing cost can be achieved.

As a metal sintered body to which the metal powder injection molding method is applied, a yoke case for a dot impact printer device can be cited (for example, see Patent Document 1). The yoke box forms a plate shape of a ring containing a soft magnetic material. Further, the outer edge portion of the ring protrudes toward one surface side, and a plurality of cylindrical cores are also protruded inside. Further, a plurality of through holes are also provided. In the metal powder injection molding method, a kneaded material of a powder of a soft magnetic material and an organic binder is injected into a cavity corresponding to the shape of the yoke case, and the obtained molded body is degreased and calcined. The yoke box is obtained.

Here, in order to achieve high dimensional accuracy in the metal powder injection molding method, it is necessary to smoothly fill the kneaded material in the cavity of the molding die. However, in the case of the yoke case described in Patent Document 1, since a plurality of cores and through holes are formed, the shape of the cavity is extremely complicated. Therefore, the flow resistance of the kneaded material tends to be high and cannot be smoothly filled. As a result, it is impossible to avoid the occurrence of molding problems such as weld lines and dimensional defects caused by poor filling.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2007-44980

An object of the present invention is to provide a metal powder injection molding die which can reliably produce a high-quality molded body having a ring-shaped plate shape by a metal powder injection molding method.

The above object is achieved by the present invention described below.

The metal powder injection molding die according to the present invention is characterized in that it can form a cavity for molding a metal powder injection molding body, the metal powder injection molding body comprising: a base portion which forms a circular plate shape; a rim portion disposed along an outer edge of one of the main faces of the base portion and forming a shape rising from the one main surface; a plurality of through holes equal to a direction orthogonal to a direction perpendicular to the one main surface of the base portion Provided at a position different from the outer edge portion and penetrating the base portion in the thickness direction; and a plurality of core portions, wherein the plurality of core portions are different from the outer edge portion and the plurality of through holes in the plan view The metal powder injection molding die includes: a first molding die having at least one side opposite to the one main surface on which at least the base portion of the metal powder injection molded body is molded a first cavity surface of the main surface; and a second molding die having a second cavity surface on which the one main surface of at least the base portion of the metal powder injection molded body is molded; and the metal powder The injection molding die includes a plurality of gates for introducing a metal powder injection molding material into the cavity, and the plurality of gates are on the first cavity surface The center point of the annular plate shape of the base portion of the metal powder injection molded body in a plan view satisfies the point symmetry relationship, and is provided in the plurality of through holes from the metal powder injection molded body. And a position at which the positions corresponding to the plurality of core portions are separated from each other.

Thereby, the fluidity and the filling property of the molding material in the cavity are ensured, and the temperature of the molding material filled in the cavity is uniformized, and the so-called melt scar is suppressed, so that it can be emitted by the metal powder. The molding method can reliably produce a metal powder injection molding die for forming a high-quality molded body having a circular plate shape.

In the metal mold for injection molding of the present invention, it is preferable that one of the openings of the gate overlaps the position corresponding to the outer edge portion in a plan view of the first cavity surface.

Thereby, one part of the molding material supplied from the gate flows in the direction of filling the outer edge portion, and the remaining portion flows in the direction of the filling base or the like. As a result, the flow efficiency of the molding material can be well dispersed, and the time until the molding material is filled into the cavity can be shortened. That is, it is possible to prevent a portion of the cavity from being filled first, and then filling the remaining portion as in the case where the filling of the molding material causes a large time lag. As a result, the unevenness of the temperature of the molding material and the like is further suppressed, the density of the molded body is more uniformized, and the generation of the melt scar is more reliably suppressed.

In the molding die for metal powder injection molding of the present invention, it is preferable that the number of the gates is n/4 or more and n/2 or less when the number of the core portions is n.

Thereby, the temperature and the like are prevented from changing during the flow of the molding material in the cavity, the density of the molded body is lowered, or a melt mark is generated, and the molding material is distributed to the gates at substantially the same timing, thereby forming the material. When the opening of the gate is passed, the deviation is less likely to occur, and the density of the molded body or the occurrence of the melt mark can be prevented, so that the filling property of the molding material can be ensured.

In the molding die for metal powder injection molding of the present invention, the number of the gates is compared Good for 3 or more and 6 or less.

Thereby, the decrease in the density of the molded body or the generation of the melt mark can be sufficiently suppressed.

In the metal mold for injection molding of the present invention, the positions of the gates are preferably located at equal distances from at least two of the through holes in a plan view of the first cavity surface.

Thereby, the flow resistance of the molding material is suppressed to a minimum, and the smooth flow is ensured, whereby the decrease in the density of the molded body or the generation of the melt mark can be more reliably suppressed.

In the metal powder injection molding die of the present invention, it is preferable that the metal powder injection molding further includes an inner edge portion which is provided along an inner edge of one of the main faces of the base portion, and is formed to be adjacent to the outer edge The portion is formed in the same height from the above-mentioned main surface.

Thereby, it is possible to obtain a molding die in which the molding material can be uniformly filled even for a cavity having a shape in which both the outer edge portion and the inner edge portion are difficult to uniformly fill.

In the molding die for metal powder injection molding of the present invention, it is preferable that the plurality of core portions satisfy a point symmetry relationship with respect to a center point of the annular plate shape of the base portion, and are disposed at equal intervals from the center point. The distance is equal.

Thereby, the smooth flow of the molding material can be ensured, and the decrease in the density of the molded body or the generation of the melt mark can be surely suppressed.

1‧‧‧forming mould

10‧‧‧ cavity

11‧‧‧1st forming die

12‧‧‧2nd forming die

101‧‧‧ base

102‧‧‧The outer edge

103‧‧‧through holes

104‧‧‧ Core Department

105‧‧‧Inner rim

111‧‧‧1st recess

115‧‧‧ gate

1151‧‧‧Area

1152‧‧‧Area

120‧‧‧1st convex

121‧‧‧2nd recess

122‧‧‧3rd recess

123‧‧‧2nd convex

P‧‧‧分模面

Fig. 1 is a cross-sectional view showing a closed state of a first embodiment of a metal powder injection molding die according to the present invention.

Fig. 2 is a plan view showing a cavity of a metal powder injection molding die shown in Fig. 1.

Fig. 3 is a cross-sectional view showing a mold opening state of the first embodiment of the metal powder injection molding die shown in Fig. 1;

Figure 4 is a partial enlarged view of the plan view shown in Figure 2.

Fig. 5 is a view showing a second embodiment of a molding die for metal powder injection molding of the present invention; A cross-sectional view of the closed mode state.

Fig. 6 is a plan view showing a cavity of a metal powder injection molding die shown in Fig. 5.

Fig. 7 is a cross-sectional view showing a mold opening state of a second embodiment of the metal powder injection molding die shown in Fig. 5;

Hereinafter, the metal powder injection molding die of the present invention will be described in detail based on the preferred embodiment shown in the drawings.

<First embodiment>

First, a first embodiment of a molding die for metal powder injection molding of the present invention will be described.

Fig. 1 is a cross-sectional view showing a mold closing state of a first embodiment of a metal powder injection molding die according to the present invention, and Fig. 2 is a plan view showing a cavity of a metal powder injection molding die shown in Fig. 1. A cross-sectional view showing a mold opening state of the first embodiment of the metal powder injection molding die shown in Fig. 1 . Further, the cross-sectional views shown in Figs. 1 and 3 are cross-sectional views taken along line A-A of Fig. 2, respectively.

The metal powder injection molding die (hereinafter simply referred to as "forming die") 1 shown in Fig. 1 includes a first molding die 11 and a second molding die 12 which are mold-openable and mold-closeable. Further, a cavity 10 for molding is formed between the first molding die 11 and the second molding die 12 in the mold closing state (the parting surface P). The cavity 10 is an example of a cavity for forming a yoke box for a dot matrix printer device.

As shown in FIGS. 1 and 2, the cavity 10 includes a base portion 101 including a cavity of a circular plate shape, and an outer edge portion 102 disposed along an outer edge of one of the two main faces of the base portion 101. And a plurality of through holes 103, which are different from the outer edge portion 102, which are scattered on the base portion 101 in a plan view orthogonal to a main surface. The base portion 101 is disposed in the thickness direction, and the plurality of core portions 104 are disposed on the base portion 101 and the outer edge portion 102 and the plurality of through holes 103 in plan view. The position is different from that of the base 101, and the inner edge portion 105 is disposed along the inner edge of one of the main faces of the base 101, and is configured to be the outer edge portion. 102 is erected from a main surface in the same thickness.

By filling the cavity 10 with the metal powder injection molding material, a metal powder injection molded body (hereinafter simply referred to as a "molded body") having a shape corresponding to the shape of the cavity 10 can be obtained. In other words, the base portion of the molded body is formed corresponding to the base portion 101, and the outer edge portion of the molded body is formed corresponding to the outer edge portion 102. The through hole of the molded body is formed corresponding to the through hole 103, and the core portion of the molded body corresponds to The core portion 104 is formed, and the inner edge portion of the molded body is formed corresponding to the inner edge portion 105.

Further, a convex portion and a concave portion corresponding to the shape of the cavity 10 are formed in the split surface P of the first molding die 11 and the second molding die 12. Specifically, in the first molding die 11 shown in FIG. 1, the first cavity surface facing the cavity 10 is provided with a thickness formed by recessing from the parting surface P and the thickness and outer diameter of the cavity 10. Corresponding to the first recess 111. The surface of the first cavity surface defining the cavity 10 constitutes a surface of a region of the base portion 101 on the other principal surface side opposite to the one main surface.

On the other hand, in the second molding die 12 shown in FIG. 1, a second cylinder surface facing the cavity 10 is provided with a substantially cylindrical shape which is formed to protrude from the split surface P and corresponds to the first concave portion 111. The first convex portion 120 is formed in a shape. The second cavity surface forms a surface of a surface of the cavity 10 which forms a region on one main surface side of the base portion 101.

In the first convex portion 120, recesses (a plurality of second concave portions 121 and third concave portions 122) are formed in portions corresponding to the plurality of core portions 104 and portions corresponding to the inner edge portions 105 (see FIG. 2, 3), the core portion 104 and the inner edge portion 105 of the cavity 10 are formed by the recess. Further, as shown in FIG. 1, the outer diameter of the first convex portion 120 is smaller than the inner diameter of the first concave portion 111, and the cavity corresponding to the difference corresponds to the outer edge portion 102. Further, in a portion of the first convex portion 120, a plurality of portions having a columnar shape thicker than the periphery are present, and the portions (the plurality of second convex portions 123) and the base portion 101 penetrating the cavity 10 in the thickness direction are connected in plurality. The holes 103 correspond.

Further, the first molding die 11 is provided with a plurality of gates 115 for introducing a metal powder injection molding material (hereinafter simply referred to as "forming material") into the cavity 10. As shown in FIG. 2, the openings of the plurality of gates 115 satisfy the point symmetry relationship with respect to the center point O of the ring, and are disposed at positions apart from the respective through holes 103 and the core portions 104 in plan view.

According to this molding die 1, the molding material can be smoothly flowed and uniformly filled in the cavity 10. As a result, the molding die 1 is a molded body capable of reliably forming a high-quality molded body capable of producing a homogeneous and dense sintered body. Further, in the case where both the outer edge portion 102 and the inner edge portion 105 are present in the cavity 10, the filling property of one of the gates 115 is lowered depending on the position of the gate 115, but according to the present invention, even for The cavity 10 of such a shape can also uniformly fill the molding material.

The inner diameter of the cavity 10 (the inner diameter of the base portion 101) is not particularly limited, and may be, for example, 15 mm or more and 200 mm or less. Further, the thickness of the cavity 10 is not particularly limited, and may be, for example, 2 mm or more and 30 mm or less.

The constituent material of the first molding die 11 and the second molding die 12 may be a ceramic material, but is generally a metal material such as heat resistant steel, super hard alloy, or stainless steel.

Further, the position of the parting surface P of the molding die 1 is not limited to the surface shown in Figs. 1 and 3, and may be set at other positions.

As shown in FIG. 2, the base portion 101 includes a cavity having a circular plate shape, and the thickness thereof is set to be about 0.5 mm or more and 3 mm or less.

The outer edge portion 102 includes an annular cavity provided along the outer edge of the base portion 101, the thickness of which is equal to the thickness of the cavity 10, and the width (the length in the radial direction of the ring) is set to be 1 mm or more and 5 mm or less. degree. Further, the step difference between the base portion 101 and the outer edge portion 102 is set to be about 0.5 mm or more and 15 mm or less.

The plurality of through holes 103 penetrate the base portion 101 in the thickness direction, and the inner diameter of the second convex portion 123 is an inner diameter of 0.5 mm or more and 5 mm or less. Also, a plurality of through holes 103 The number of the second convex portions 123 is not particularly limited, and is set to be eight or more and 200 or less.

As shown in FIG. 2, a plurality of core portions 104 are arranged at equal intervals in the circumferential direction of the ring. Each of the core portions 104 is formed in a substantially trapezoidal shape in plan view, and has a long diameter of 2 mm or more and 10 mm or less, and a short diameter of 1 mm or more and 8 mm or less. Further, the thickness of each of the core portions 104 is equal to the thickness of the cavity 10, and is preferably set to be equal to the thickness of the outer edge portion 102 and the inner edge portion 105. Further, the arrangement pattern of the core portions 104 is not particularly limited, and may be arranged at different intervals.

Further, the step of the base portion 101 and each of the core portions 104 is not particularly limited, and is set to be about 0.5 mm or more and 15 mm or less.

Further, the number of the core portions 104 is not particularly limited, and is set to be four or more and 100 or less (12 in FIG. 2). Further, the arrangement of the core portion 104 satisfies the point symmetry relationship with respect to the center point O of the ring, and is set to a position equal to the distance from the center point O. By providing the core portion 104 at the above position, the smooth flow of the molding material can be ensured, and the decrease in the density of the molded body or the generation of the melt mark can be surely suppressed.

Further, the through holes 103 are arranged one or more in order to have an equal positional relationship with respect to each of the core portions 104. Specifically, in the cavity 10 shown in FIG. 2, one through hole 103 is disposed in each of the positions on the center point O side of each core portion 104 and the outer side of each core portion 104. Therefore, the number of the through holes 103 is preferably an integral multiple of the number of the core portions 104. In FIG. 2, two through holes 103 are disposed in each of the core portions 104, and the through holes 103 disposed on the center point O side of each core portion 104 satisfy a point symmetry relationship with respect to the center point O, and are equally spaced. In the arrangement, on the other hand, the through holes 103 disposed on the outer side of each core portion 104 satisfy the point symmetry relationship with respect to the center point O, and are arranged at equal intervals. Further, the arrangement pattern of the through holes 103 is not particularly limited, and may be arranged at different intervals.

The inner edge portion 105 includes an annular cavity disposed along the inner edge of the base portion 101, the thickness of which The thickness of the cavity 10 is equal to the thickness of the cavity 10 (the length of the ring in the radial direction) is set to be 1 mm or more and 5 mm or less. Further, the step difference between the base portion 101 and the inner edge portion 105 is set to be about 0.5 mm or more and 15 mm or less.

Further, it is preferable that the thicknesses of the outer edge portion 102, the core portion 104, and the inner edge portion 105 are set to be equal.

Here, as described above, the plurality of gates 115 are provided in the first molding die 11, and the arrangement of the openings is as shown in FIG. 2, and the point O is satisfied with respect to the center point O of the ring, and is viewed in a plan view. It is located at a position separated from each of the through holes 103 and each of the core portions 104. By arranging the gate 115 in this manner, the temperature of the molding material filled in the cavity 10 is uniformized. As a result, when the molding materials introduced from the plurality of gates 115 are joined together in the cavity 10, the temperature of the molding material is uniform, and therefore it is difficult to mix with each other, thereby suppressing the occurrence of so-called melt marks and changing the density of the molded body. Evenly.

Further, three gates 115 are formed in the opening of the first molding die 11, and the openings are located at positions outside the core portion 104. Further, the opening is provided at a position where a part thereof overlaps with a position corresponding to the outer edge portion 102 in plan view.

Figure 4 is a partial enlarged view of the plan view shown in Figure 2.

As shown in FIG. 4, the opening of the gate 115 is disposed at a position where a portion thereof overlaps with a position corresponding to the outer edge portion 102 in a plan view of the first cavity surface, and the remaining portion overlaps with the base portion 101. By setting the position of the opening of the gate 115 in this way, a part of the molding material supplied from the gate 115 flows in the direction of filling the outer edge portion 102 (arrow F1 shown in FIG. 4), and the remaining portion is directed to the filling base 101 or the like. (arrow F2 shown in Fig. 4) flows. As a result, the flow of the molding material can be efficiently dispersed, so that the time until the molding material is filled in the cavity 10 can be shortened. That is, it is possible to prevent a portion of the cavity 10 from being filled first, and then filling the remaining portion as in the case where the filling of the molding material causes a large time lag. As a result, the unevenness of the temperature of the molding material and the like is further suppressed, and the density of the molded body is more uniformized, and the generation of the melt mark can be further reliably suppressed.

In this case, the region of the opening of the gate 115 which overlaps the outer edge portion 102 in plan view (the region 1152 shown in FIG. 4) is preferably set to a region overlapping the base portion 101 (the region 1151 shown in FIG. 4). )narrow. Thereby, the balance of the flow of the shaped material is optimized. Further, the area of the region 1152 is preferably 5% or more and 45% or less of the area of the region 1151, and more preferably 10% or more and 40% or less.

The number of the gates 115 is not particularly limited, and is preferably set to n/4 or more and n/2 or less when the number of the core portions 104 is n. Thereby, a high filling property of the molding material is ensured. In the case where the number of the gates 115 is lower than the lower limit value, since the number of the gates 115 is small, the temperature of the molding material changes during the flow of the molding material in the cavity 10, and the molded body is formed. The density drops, or the flaws are created. On the other hand, when the number of the gates 115 is larger than the above upper limit value, since the number of the gates 115 is too large, it is difficult to distribute the molding materials to the gates 115 at the same timing, and the molding material passes. The timing at which the opening of the gate 115 is deviated causes the density of the formed body to decrease, or the flaw of the melt mark is generated.

Further, in the case of FIG. 2, the number of the core portions 104 is twelve, so the number of the gates 115 is preferably three or more and six or less.

Further, the number of the gates 115 is appropriately set in accordance with the size of the cavity 10, but it is preferably three or more and six or less in terms of the inner diameter and the thickness as described above. By setting the number of the gates 115 to this extent, it is possible to sufficiently suppress the decrease in the density of the molded body or the generation of the melt marks.

Further, since the opening of the gate 115 is provided at a position separated from each of the through holes 103 or the core portions 104 in plan view as described above, it is difficult to hinder the supply of the molding material from the gate 115, and smooth filling can be achieved. In this case, the separation distance L1 between the opening of the gate 115 and each of the through holes 103 in plan view or the separation distance L2 of the opening of the gate 115 and the core portion 104 in plan view is preferably set to 1 mm or more, respectively. Good setting is 2 mm or more.

Further, the opening position of the gate 115 is preferably set to a position at which the at least two through holes 103 are at equal distances. By setting it at the above position, it is possible to ensure a smoother flow of the formed material. Further, it is possible to surely suppress the decrease in the density of the formed body or the generation of the melt mark. This is because when the through hole 103 provided in the cavity 10 serves as a resistance factor that hinders the flow of the molding material, the flow resistance can be minimized by setting the position of the gate 115 as described above. In FIG. 4, the through holes 103 are respectively located on both sides in the circumferential direction of the opening of each gate 115, and the distance L1 between the through holes 103 and the gate 115 is equal.

Further, the position of the opening of the gate 115 may be set at a position equidistant from the three or more through holes 103.

Although the first molding die 11 and the second molding die 12 have been described above, the molding die may be divided into a plurality of blocks or a nesting structure (embedded block) as needed. Further, although not shown, the first molding die 11 and the second molding die 12 are provided with an eject pin that can protrude into the cavity 10. After the molding material is formed, the molded body can be released from the cavity 10 by projecting the ejection pin into the cavity 10.

Further, a vent hole is provided in the first molding die 11 or the second molding die 12 as needed. By providing the vent holes, excess gas in the cavity 10 can be released to the outside, thereby improving the filling property of the molding material.

The position at which the vent hole is formed is not particularly limited, and examples thereof include the parting surface P and the vicinity of the eject pin. Further, when the first molding die or the second molding die has a nesting structure, a vent hole may be provided in the mating abutting surface.

Further, the gate 115 may be provided on the second molding die 12 side, and a part of the plurality of gates 115 may be provided on the side of the first molding die 11 and the other portion may be provided on the second molding die 12 side.

Further, the size of the cavity 10 is set in accordance with the size of the formed body to be manufactured.

The formed body is then subjected to a degreasing treatment and a calcination treatment to form a metal sintered body. This metal sintered body becomes the yoke case described above.

Here, since the molded body shrinks during the degreasing treatment or the calcination treatment, when the molded body is produced, the size of the molded body is designed in consideration of the shrinkage ratio. Further, the shrinkage ratio varies depending on the shape of the formed body, so that it is formed by the cavity 10 of a complicated shape as shown in Figs. In the form, the shrinkage rate is locally different. Therefore, when designing the cavity 10, it is preferable to reflect the unevenness of the above shrinkage ratio.

Further, the metal sintered body is usually subjected to a polishing treatment. Therefore, when the cavity 10 is designed, it is reflected that the amount of polishing in the polishing process is also effective. Thereby, the metal sintered body conforming to the design can be efficiently manufactured.

<Second embodiment>

Next, a second embodiment of the molding die for metal powder injection molding of the present invention will be described.

Fig. 5 is a cross-sectional view showing a closed state of a second embodiment of a metal powder injection molding die according to the present invention, and Fig. 6 is a plan view showing a cavity of a metal powder injection molding die shown in Fig. 5; A cross-sectional view showing a mold opening state of the second embodiment of the metal powder injection molding die shown in Fig. 5 . Further, the cross-sectional views shown in Figs. 5 and 7 are cross-sectional views taken along line B-B of Fig. 6, respectively.

In the following, the second embodiment will be described, but the differences from the first embodiment will be mainly described, and the description of the same matters will be omitted. In the same manner as in the first embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the detailed description thereof will be omitted.

In the second embodiment, the mold removal chamber 10 is the same as the first embodiment except that the inner edge portion 105 is not included. Even in such a form, according to the molding die 1, a high-quality molded body capable of producing a homogeneous and dense sintered body can be reliably formed.

Further, in the first molding die 11 and the second molding die 12 of the present embodiment, convex portions and concave portions corresponding to the cavity 10 are formed. In other words, the second molding die 12 shown in FIGS. 5 to 7 is the same as the second molding die 12 shown in FIGS. 1 to 3 except that the third concave portion 122 corresponding to the inner edge portion 105 of the cavity 10 is omitted.

Hereinabove, the present invention has been described based on preferred embodiments, but the present invention is not limited thereto.

For example, in the forming mold, any structure may be added in addition to the above-described structure.

Further, in the molding die for metal powder injection molding of the present invention, as long as it is a metal product having the shape of the above-mentioned annular plate, it is possible to form a molded article of a metal product which can be used for any purpose.

1‧‧‧forming mould

10‧‧‧ cavity

11‧‧‧1st forming die

12‧‧‧2nd forming die

101‧‧‧ base

102‧‧‧The outer edge

103‧‧‧through holes

104‧‧‧ Core Department

105‧‧‧Inner rim

111‧‧‧1st recess

115‧‧‧ gate

120‧‧‧1st convex

121‧‧‧2nd recess

122‧‧‧3rd recess

123‧‧‧2nd convex

P‧‧‧分模面

Claims (7)

A metal powder injection molding die for forming a mold cavity for molding a metal powder injection molding body, the metal powder injection molding body comprising: a base portion forming a circular plate shape; an outer edge a portion disposed along an outer edge of one of the main faces and forming a shape rising from the one main surface; a plurality of through holes equal to a direction from a direction orthogonal to the one main surface of the base The base portion is penetrated in a thickness direction from a position different from the outer edge portion; and the plurality of core portions are equal to the one of the positions different from the outer edge portion and the plurality of through holes in the plan view The metal powder injection molding die includes: a first molding die having another main body on which the at least one base portion of the metal powder injection molding body is formed opposite to the one main surface; a first cavity surface of the surface; and a second molding die having a second cavity surface on which the one main surface of the base portion of the metal powder injection molded body is molded; and the metal powder is injected The molding die for molding includes a plurality of gates for introducing a metal powder injection molding material into the cavity, and the plurality of gates are provided on the metal cavity injection molding body in a plan view of the first cavity surface The center point of the shape of the circular plate of the base portion satisfies the position of the point symmetry relationship, and is disposed at a position apart from a position corresponding to the plurality of through holes and the plurality of core portions of the metal powder injection molded body One of the openings of the gate overlaps with a position corresponding to the outer edge portion in a plan view of the first cavity surface. The metal powder injection molding die according to claim 1, wherein when the number of the core portions is n, the number of the gates is n/4 or more and n/2 or less. The metal powder for injection molding of claim 1 or 2, wherein the gate is The number is three or more and six or less. The metal powder injection molding die according to claim 1 or 2, wherein each of the gates is located at a position equidistant from at least two of the through holes in a plan view of the first cavity surface. The metal powder injection molding die according to claim 1 or 2, wherein the metal powder injection molding further comprises: an inner edge portion provided along an inner edge of one of the main faces of the base portion, and formed to be the outer edge The portion is formed in the same height from the above-mentioned main surface. The metal powder injection molding die according to claim 1 or 2, wherein the plurality of core portions satisfy a point symmetry relationship with respect to a center point of a circular plate shape of the base portion, and are disposed at equal intervals from the center point The distance is equal. A metal powder injection molding die for forming a mold cavity for molding a metal powder injection molding body, the metal powder injection molding body comprising: a base portion forming a circular plate shape; an outer edge a portion disposed along an outer edge of one of the main faces and forming a shape rising from the one main surface; a plurality of through holes equal to a direction from a direction orthogonal to the one main surface of the base The base portion is penetrated in a thickness direction from a position different from the outer edge portion; and the plurality of core portions are equal to the one of the positions different from the outer edge portion and the plurality of through holes in the plan view The metal powder injection molding die includes: a first molding die having a first concave portion formed to be recessed from the mold division surface; and a second molding die having a self-splitting mold a first convex portion having a smaller outer diameter than the inner diameter of the first concave portion, and the first convex portion of the second molding die having the plurality of cores of the metal powder injection molded body a plurality of second recesses corresponding to the core portion and the above a plurality of second protrusions corresponding to the plurality of through holes of the metal powder injection molded body; the first molding die includes a plurality of gates for introducing a metal powder injection molding material into the cavity, and the plurality of gates a position that satisfies a point symmetry relationship with respect to a center point of the first concave portion in a plan view of the split surface, and is provided at a position corresponding to the plurality of second concave portions and the plurality of second convex portions a position at which it leaves; in a plan view of the split surface, a portion of the opening of the gate overlaps with a position corresponding to the outer edge portion.