JP2012240097A - Method of manufacturing powder compression molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a molding in which a thickness-directional hardness unevenness and a width-directional hardness unevenness are restrained effectively from being generated in the molding having an irregular cubic shape.SOLUTION: The method of manufacturing the molding includes a filling process for filling a raw material 50 containing powder, into a molding space formed of a mill body 2 and a molding face 42 of a lower rod 4 arranged in an inside of the mill body 2, and a molding process for making an upper rod 3 go down into the mill body 2, to compression-mold the raw material 50. A rod having a recessed part on its molding face is used as the lower rod. An upper part of the raw material 50 filled into the molding space is pressed partially by a pusher 8 of a shape smaller than an opening end shape of the mill body 2, while filling the raw material 50 into the molding space, or after finishing the filling, in the filling process.

Description

  The present invention relates to a method for producing a powder compression molded body.

  For the purpose of imparting a design property to a powder compression molded body to enhance a sense of quality, a powder compression molded body rich in three-dimensional design is required. In such a molded body, since the surface is not flat and has a three-dimensional shape of unevenness, there is a tendency for troubles to occur in molding as compared with the case where a molded body having a flat surface is molded. For example, unevenness in the hardness may occur due to the fact that each part of the molded body cannot be compressed uniformly.

  Therefore, it has been proposed that the powder raw material is preformed prior to molding and compression is performed uniformly. For example, in Patent Document 1, in a method for manufacturing a convex solid powder cosmetic, first, the powder cosmetic is compressed with a male mold having a deep concave press head, and the powder cosmetic is moved to the central convex portion. Later, a male die having a concave press head corresponding to the convex surface of the target convex solid powder cosmetic is performed.

  In Patent Document 2, cosmetic powder that has already been filled is pre-compressed with a pressing die having a conical concave pressing portion, and the upper surface of the filling powder is raised at the center, and the filling powder is in this raised state. It describes that the body is compressed with a compression jig and molded. By doing so, it is described in the same document that abundant powder in the center moves to the periphery during compression and can be uniformly compression-molded.

Japanese Patent Laid-Open No. 5-201829 Japanese Unexamined Patent Publication No. 7-010721

  As described above, any preforming that has been conventionally performed is preformed by applying a molding load to the entire surface of the powder filled in the die. Specifically, in Patent Document 1, the powder in the direction orthogonal to the molding direction is formed by performing the main molding after moving the powder to the center of the die by the preforming performed on the entire surface of the powder. It is considered that the difference in body compression ratio is reduced, and the compression ratio of the obtained molded body is made uniform. In Patent Document 2, the powder is formed at the center of the die by pre-forming on the entire surface of the powder, and the powder is molded in that state, resulting in a uniform compression rate of the compact. It is thought that. The method for producing a powder compression molded body having such a preforming is effective when the molding surface of the lower arm is smooth, and if the entire surface of the powder after the preforming is compressed, the powder is molded in the die. Was moving efficiently. However, in the case of using the lower mold having a concave molding surface, it is not easy to obtain a molded product having a uniform hardness even if the above-described preliminary molding is performed.

  Therefore, the present invention provides a method for producing a powder compression molded product that can eliminate the occurrence of hardness unevenness in the thickness direction and width direction, which is a problem that cannot be solved by the above-described prior art, and that occurs when the lower eyelid is concave. To do.

The present invention includes a filling step of filling a molding space formed by a mortar and a molding surface of a lower jaw arranged in the mortar with a raw material containing powder, and lowering the upper jaw into the mortar. A method for producing a powder compression molded body comprising a molding step of compression molding the raw material,
As the lower iron, use the one that has a recess in its molding surface,
In the filling process, the powder that partially presses the upper part of the raw material filled in the molding space with the pusher having a shape smaller than the opening end shape of the mortar while filling the raw material in the molding space or after completion of filling. A method for producing a compression molded body is provided.

  According to the production method of the present invention, the occurrence of uneven hardness in the thickness direction and uneven hardness in the width direction is effectively suppressed in a molded article having a complicated three-dimensional shape of unevenness rich in three-dimensional design. Therefore, according to the manufacturing method of this invention, the freedom degree of the three-dimensional design of a molded object becomes high.

Fig.1 (a) is a perspective view which shows an example of the powder compression molding body obtained with the manufacturing method of this invention, FIG.1 (b) is a side view of the powder compression molding body shown to Fig.1 (a). is there. FIG. 2 is a cross-sectional view showing an outline of a powder compression molding apparatus suitably used for carrying out the production method of the present invention. FIG. 3 is a schematic diagram showing a state of the powder compression molding apparatus when the raw material is preliminarily pressed by the pusher. 4A to 4C are explanatory views of a preliminary pressing process of the raw material by the pusher. 5 (a) to 5 (c) are explanatory views of the molding process of the powder compression molded body by the production method of the present invention. 6 (a) to 6 (c) are explanatory views of a molding process of a powder compression molded body by a conventional manufacturing method. 7A to 7C are graphs showing the hardness distribution in the powder compression molded product obtained in Example 1. FIG. 8A to 8C are graphs showing the hardness distribution in the powder compression molded body obtained in Comparative Example 1. FIG.

  The present invention will be described below based on preferred embodiments with reference to the drawings. 1 (a) and 1 (b) show an example of a powder compression molded article that is suitably manufactured according to the manufacturing method of the present invention. The powder compression-molded body 10 shown in FIG. 1 (b) is compression-molded with the vertical direction of the paper surface as the compression direction. The powder compression molding 10 has a lower portion 11 rich in three-dimensional design. The lower part 11 has a shape of a lower dent whose cross-sectional area decreases toward the bottom, and has a mortar shape as shown in FIGS. 1 (a) and 1 (b). The powder compression-molded body 10 can take various three-dimensional designs depending on the shape of the molding surface of the upper and lower eyelids used in the manufacturing process. For example, it can be formed by imagining the shape of a flower or a character. The powder compression molding 10 shown to Fig.1 (a) and (b) is formed in the image of a flower. The mortar-shaped lower part 11 in the molded body 10 is formed in a three-dimensional manner in the image of an aggregate of petals from the bottom surface side. The upper portion 12 of the powder compression molded body 10 also has a shape rich in three-dimensional design, and is three-dimensionally formed by imagining an aggregate of petals from the top side. Conventionally, when such a molded article rich in three-dimensionality is manufactured by compression molding, it is not easy to make the hardness uniform in each part. In particular, the hardness in the upper central region of the powder compression molded body 10 tended to be lower than the hardness in the peripheral region. This tendency is remarkable when the upper portion 12 of the powder compression molded body 10 has a plurality of unevenness having a large difference in height, and the angle formed between the tangent line of the unevenness and the X axis (see FIG. 2) is the raw material powder. It became clear by examination of inventors that it becomes very remarkable when it is larger than the angle of repose of the body. However, according to the manufacturing method of the present invention, a molded body having a uniform hardness in each part can be easily manufactured.

  FIG. 2 is a sectional view showing an outline of the entire powder compression molding apparatus preferably used for manufacturing the powder compression molding body 10 shown in FIGS. 1 (a) and 1 (b). A powder compression molding apparatus 1 shown in the figure is an apparatus for producing a powder compression molded body 10 having a high degree of three-dimensional design by compression molding a raw material containing powder. As shown in FIG. 2, the powder compression molding apparatus 1 includes a mortar body 2 having a through hole 21 extending in the vertical direction, an upper punch 3 that is inserted downward from the upper side of the through hole 21, and the through hole 21. And a lower collar 4 that is inserted upward from the lower side. The Y direction in the figure is the vertical direction of the powder compression molding apparatus 1 and the vertical direction. The X direction in the figure is a direction orthogonal to the Y direction and is a horizontal direction.

  The powder compression molding apparatus 1 includes a tableting table 6 attached in the horizontal direction. A through hole is provided in the center of the tableting table 6, and the die 2 is fitted in the through hole. The mortar body 2 is made of a metal rigid body and has a cylindrical shape having a cylindrical through-hole 21 extending in the Y direction.

  The upper collar 3 is inserted from the upper side of the through hole 21 and can move up and down in the through hole 21. The upper arm 3 is made of a metal rigid body. The upper collar 3 is held integrally with the holder 31 by an upper collar holder 31 arranged on the upper side thereof. The upper rod holder 31 is supported by a connecting rod (not shown) connected to the crankshaft. In a state where the upper arm 3 is inserted into the through hole 21 of the mortar 2, a slight clearance is formed between the upper heel 3 and the wall surface of the mortar 2. With the clearance formed, the upper collar 3 can move up and down in the through hole 21. The moving means of the upper rod 3 is not limited to the connecting rod connected to the crankshaft, but may be a hydraulic cylinder, an air cylinder, a ball screw press using an electric motor, or the like.

  The bottom surface of the upper collar 3, that is, the surface facing the lower collar 4 is a molding surface 32. The molding surface 32 can be a flat surface or a surface having an uneven portion (hereinafter simply referred to as an uneven surface). From the viewpoint of imparting design properties to the upper portion 12 of the target powder compression molded body 10, the molding surface of the upper collar 3 is preferably an irregular surface, and more preferably has a plurality of irregularities on the surface. The molding surface is complementary to the shape of the upper part 12 of the target powder compression molding 10.

  The lower punch 4 is inserted from the lower side of the through hole 21 of the mortar 2 and can move up and down in the through hole 21. The lower collar 4 is made of a metal rigid body in the same manner as the upper collar 3 described above. The lower rod 4 is held integrally with the holder by a lower rod holder (not shown) disposed on the lower side thereof. In a state where the lower eyelid 4 is inserted into the through hole 21 of the mortar body 2, a slight clearance is formed between the lower heel 4 and the wall surface of the mortar body 2. With this clearance formed, the lower collar 4 can move up and down in the through-hole 21.

  The upper surface of the lower collar 4, that is, the surface facing the upper collar 3 is a molding surface 42. The molding surface 42 is a concave surface. The molding surface 42 is complementary to the shape of the lower portion 11 of the target powder compression molding 10.

  In a state where the lower punch 4 is inserted into the through-hole 21 of the mortar 2, a molding space filled with the raw material containing powder is formed by the molding surface 42 of the lower heel 4 and the wall surface of the mortar 2. Is done.

  At the center of the molding surface 42 of the lower collar 4, a lower collar through hole 41 that penetrates the lower collar 4 in the vertical direction is provided. A protruding core 5 that is complementary to the lower collar through hole 41 is inserted into the lower collar through hole 41. The protruding core 5 is installed in the lower punch through-hole 41 in a state where the upper end surface is smoothly connected to the molding surface 42 so that the upper end surface is a continuous surface from the molding surface 42 of the lower punch 4. Yes. It becomes a continuous surface from the molding surface 42. The upper end surface of the core 5 is preferably a flat surface, but is not limited thereto, and may be a convex surface or a concave surface as long as it is a continuous surface from the molding surface 42. The upper end surface of the core 5 forms part of the molding surface 42 of the lower collar 4.

  The lower end of the core 5 is connected to lifting means (not shown) of the core 5. As the lifting means, for example, an air cylinder, a hydraulic cylinder, a cam mechanism, a ball screw press using an electric motor, or the like can be used.

  The powder compression molding apparatus 1 includes a feed shoe 7 that supplies a raw material containing powder to the through-hole 21 of the mortar 2 on the upper surface of the tableting table 6. The feed shoe 7 is connected to a hopper (not shown) disposed on the upper side of the feed shoe 7. The raw material containing the powder is continuously supplied from the hopper (not shown) to the feed shoe 7. The feed shoe 7 and the tableting table 6 are relatively movable in the X direction.

  When the feed shoe 7 moves onto the through hole 21 of the mortar 2, the raw material is supplied into the molding space through a supply port (not shown) on the bottom surface side of the feed shoe 7. During the movement, the bottom surface of the feed shoe 7 and the top surfaces of the tableting table 6 and the mortar body 2 are flush with each other. The raw material supplied into the molding space fills the molding space and is scraped off by the bottom surface of the feed shoe 7. As a result, a certain amount of raw material is filled into the molding space.

  A pusher 8 is attached to the feed shoe 7. The pusher 8 is supported by a support member (not shown) attached to the housing 7 a of the feed shoe 7 and moves together with the feed shoe 7.

  FIG. 3 shows a state in which the feed shoe 7 is located on a molding space formed by the molding surface 42 of the lower punch 4 and the inner wall of the mortar body 2. The pusher 8 includes a pressing part 8a, a support part 8b, and an elevating part 8c. The pressing portion 8a is made of a flat plate member having an upper surface and a lower surface. The pressing portion 8 a is located in the housing 7 a of the feed shoe 7. The pressing portion 8a has a shape whose contour shape when viewed in plan is smaller than the open end shape when the mortar 2 is viewed in plan. The pressing portion 8a is disposed at a position corresponding to the deepest portion of the recess in the molding surface 42 of the lower collar 4 in a state where the feed shoe 7 is positioned in the molding space from the viewpoint of further suppressing the hardness unevenness at the time of molding. Preferably it is done. In FIG. 3, the bottom surface of the pressing portion 8 a faces the molding surface 42 of the lower collar 4 in a state where the feed shoe 7 is positioned on the molding space. That is, the pressing portion 8a is located at a substantially central portion of the open end of the mortar body 2 in plan view.

  The lower end of the support portion 8b of the pusher 8 is connected to the upper surface of the pressing portion 8a, while the upper end is connected to the elevating portion 8c. The raising / lowering part 8c consists of an air cylinder, a hydraulic cylinder, etc., for example. Thereby, the pressing part 8a of the pusher 8 can be moved up and down.

  In the method for manufacturing a powder compression molded body using the molding apparatus 1 shown in FIG. 2, as shown in FIG. 4 (a), in the molding space formed by the molding surface 42 of the mortar 2 and the lower collar 4, A filling step of filling the raw material 50 including powder is performed. The raw material 50 is filled using the feed shoe 7 as described above. In this state, the pressing portion 8 a of the pusher 8 attached to the feed shoe 7 is in a state of being retracted near the top surface of the housing 7 a of the feed shoe 7. Therefore, the raw material 50 exists between the lower surface of the pressing portion 8 a of the pusher 8 and the molding surface 42 of the lower rod 4.

  When the raw material 50 is filled in the molding space by the feed shoe 7 or when the raw material 50 is fully filled in the molding surface 42, the pusher 8 is lowered as shown in FIG. Press. As described above, the pressing portion 8a of the pusher 8 has a contour shape when viewed in plan view that is smaller than the open end shape when viewed in plan view of the mortar 2. The pressing of the raw material 50 is partial. Specifically, the upper part of the raw material 50 filled in the molding space is partially pressed. A portion of the raw material 50 that is pressed by the pusher 8 becomes a consolidated portion 50a that is consolidated as compared to a portion that is not pressed. Since the pressing portion 8a of the pusher 8 is located at a substantially central portion of the open end of the mortar body 2, the consolidated portion 50a is generated at a substantially central portion of the upper portion of the raw material 50 filled in the molding space. . In the consolidated part 50a, the fluidity of the particles constituting the consolidated part 50a is lower than that of the particles present in the part that has not been pressed. However, the particles constituting the consolidated portion 50a are not pressed together and have fluidity.

  The pusher 8 that pressed the raw material 50 by the lowering then moves up as shown in FIG. 4C, and the pressing portion 8 a retracts to the vicinity of the top surface of the housing 7 a of the feed shoe 7. As the pusher 8 rises, a space is created below the pressing portion 8a of the pusher 8, and unconsolidated raw material flows into the space. As a result, the space between the lower surface of the pressing portion 8a of the pusher 8 and the molding space is filled with the raw material 50.

  After the reciprocating operation of the pusher 8 ascending and descending shown in FIGS. 4B and 4C is performed once or twice or more, the feed shoe 7 is retracted horizontally from the position of the molding space. When the raw material 50 filled in the molding space is scraped off by the housing 7 a of the feed shoe 7, the upper punch 3 is lowered into the mortar 2. Then, a compression molding process for compressing and molding the raw material 50 is performed by abutting the upper collar 3 and the lower collar 4. Thereby, the target powder compression molding 10 is obtained.

  When the powder compression molded body 10 is manufactured in this way, the upper iron 3 is raised and retracted to the retracted position. Further, when the upper collar 3 is retracted or when the upper collar 3 is retracted, the projecting core 5 inserted into the through hole 41 of the lower collar 4 is projected upward, and the molded body 10 in the lower collar 4 is projected. Take out.

  According to the manufacturing method of this embodiment having a step of partially pressing the raw material 50 with a weak force, when compared with a molded body having the same density, the hardness is higher than that of a molded body obtained by a conventional molding method. And the powder compression molding 10 with a small dispersion | variation in the hardness between each site | part is obtained. The reason why such an advantageous effect is achieved is not clear in detail, but the present inventors consider that this is because of the mechanism described below. Hereinafter, the mechanism will be described with reference to FIG.

  As shown in FIG. 5A, when the raw material 50 is partially pressed with a weak force by the pusher 8, the consolidated portion 50 a generated by the pressing is less fluid than the other portions in the raw material 50. As described above, the consolidated portion 50a is formed in the substantially central portion of the upper portion of the raw material 50 filled in the molding space. When compression molding is performed by lowering the upper collar 3 in this state, parts other than the consolidated part 50a, which is a highly fluid part, move along the wall surface of the lower collar 4 toward the center of the molding space. To do. Specifically, as shown in FIG. 5 (b), a portion of the raw material 50 located around the consolidation portion 50a formed in the substantially upper central portion is directed toward the center of the molding space. And move actively. On the other hand, since the fluidity of the consolidated portion 50a is reduced, it is more difficult to move than other portions of the raw material 50, and remains in the vicinity of the lower portion of the upper bowl 3. For these reasons, as shown in FIG. 5 (c), when the compression molding is completed, the raw materials 50 gather near the center of the molding space, and the compression ratio in the depth direction of the molded body is the entire molded body. It becomes uniform. For these reasons, it is possible to increase the hardness of the central region of the upper part of the molded body, which is a part where it is difficult to increase the hardness by the conventional molding method. The hardness becomes uniform. In addition, the hardness can be increased. Further, by adjusting the degree of pressing by the pusher 8, the filling property of the raw material and the hardness of the upper central region of the obtained molded body 10 can be easily controlled.

  On the other hand, as shown in FIG. 6A, when the contour shape in plan view of the pressing portion 8a of the pusher 8 is substantially the same as the open end shape of the mortar 2, that is, the molding space is filled. When the upper portion of the raw material 50 is pressed all over, the entire upper portion of the raw material 50 is consolidated to form a consolidated portion 50a ′. The fluidity of the powder is reduced in the entire consolidated portion 50a '. When the upper iron 3 is lowered under this state and compression molding is performed as shown in FIG. 6B, the fluidity of the powder is reduced in the entire area of the upper portion of the raw material 50. It is gradually compressed from the bottom toward the bottom. This operation is basically the same as the operation shown in FIG. Even if compression molding further proceeds from the state shown in FIG. 6B to the state shown in FIG. 6C, the powder located near the lower part of the molding space, which is a highly fluid portion of the raw material 50 Is only compressed along the shape of the molding space. Therefore, this method does not perform the entire consolidation shown in FIG. 6A, and there is no difference from the method of performing the main compression directly. In the molded body thus obtained, the compressibility of each part of the molded body is not constant, resulting in uneven hardness. In particular, since the compression ratio in the upper central region of the molded body is significantly reduced as compared with other parts, the hardness in the upper central region is reduced. In particular, the occurrence of unevenness in hardness becomes more prominent when the molding surface of the upper collar 3 is an uneven surface. The present inventors have found that the hardness tends to be lower than the hardness at.

  In the present embodiment, from the viewpoint of making the above-described advantageous effects more prominent, the consolidation of the raw material 50 by pressing with the pusher 8 may be a low pressure that does not cause a bonding force between the powders. preferable. Specifically, the pressure at the time of pressing by the pusher 8 depends on the specific material of the raw material 50 and the like, but is 0.1 to 20.0%, particularly 0.5 to 0.5% of the molding pressure when performing compression molding. It is preferable to set it as 10.0%. Specifically, for example, it is preferably 100 to 1020 kPa, particularly 200 to 820 kPa. On the other hand, the molding pressure at the time of compression molding is set higher than the pressure at the time of pressing by the pusher 8 so that the powders are bonded to each other. Specifically, the compression pressure when performing compression molding is preferably 5 to 35 MPa, and particularly preferably 10 to 30 MPa, on the condition that it is higher than the pressure during pressing by the pusher 8.

  Moreover, the pressing of the raw material 50 by the pusher 8 can be performed once or twice or more. As a result of the study by the present inventors, it has been found that the desired effect can be obtained even if the pressing by the pusher 8 is performed only once. Therefore, in consideration of the productivity of the molded body 10, it is advantageous to perform the pressing by the pusher 8 only once. In relation to the pressing by the pusher 8, the speed at which the pusher 8 is raised and lowered is 5 to 500 mm / sec, particularly 20 to 100 mm / sec. The powder pressed by the lower surface of the pressing portion 8a of the pusher 8 It is preferable from the viewpoint of reliably compressing and efficiently increasing the density of the molded body.

  The degree to which the pusher 8 is lowered is such that the lower surface of the pressing portion 8a of the pusher 8 is located at the same position as the upper surface of the die 2 at the lowest lowered position where the pusher 8 is lowered from a position higher than the upper surface of the die 2. In order to further increase the hardness of the molded body 10, it is preferable that the degree is as follows. When the lower surface of the pressing portion 8a at the lowest descending position of the pusher 8 is at the same position as the upper surface of the mortar 2, the arrangement and size of the consolidated portion 50a generated by the pressing are optimized, and the molded body is more effectively produced. This is because the unevenness of hardness can be suppressed.

  As described above, the shape of the pressing portion 8a of the pusher 8 in plan view is smaller than the opening end shape of the mortar body 2 in plan view, and the area of the pressing portion 8a in plan view is 10 to 70%, particularly 15 to 60% of the area of the open end in plan view of the body 2 is preferable from the viewpoint of successfully obtaining the molded body 10 having a more uniform hardness.

  By preliminarily forming the consolidated portion 50a by pressing the raw material 50 by the pusher 8, the mass of the raw material 50 existing in the molding space is equal to the raw material 50 existing in the molding space when the pressing by the pusher 8 is not performed. The mass is increased. Therefore, in the case where a molded body having the same mass as that of the molded body manufactured when the pusher 8 is not pressed is manufactured by pressing with the pusher 8, the lower side of the through hole 21 of the mortar 2 is used. The degree of insertion of the lower eyelid 4 that is inserted upward is set larger than the case where the pusher 8 is not pressed and the volume of the molding space is made smaller than the case where the pusher 8 is not pressed.

  In the case where the deepest portion of the recess in the molding surface 42 of the lower collar 4 used in the present embodiment is a substantially flat surface, the contour shape of the pressing portion 8a in plan view as the pusher 8 is substantially the same as that described above. It is preferable to use a shape that is substantially the same shape as the contour shape of the flat surface in plan view. As a result, the consolidated portion 50a can be effectively generated, and as a result, the molded body 10 having a more uniform hardness in each portion can be obtained.

  The raw material 50 of the powder compression molded body 10 includes, for example, various powders and various components such as oil components blended as necessary, and these components are mixed. From the viewpoint of facilitating the unpressed raw material 50 to flow into the space generated by the pusher 8 being pushed upward after the raw material 50 is pressed by the pusher 8, it is preferable to use a raw material 50 having a small angle of repose. When the powder compression molding 10 is a bathing agent tablet, for example, a powder raw material containing, for example, a multilayer, sodium carbonate, succinic acid, fumaric acid, dextrin, a fragrance, and a pigment can be used as the raw material 50.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the scope of the present invention is not limited to such examples.

[Example 1]
Using the powder compression molding apparatus 1 shown in FIG. 2, a powder compression molding 10 having the shape shown in FIGS. 1A and 1B was manufactured. The maximum thickness of the molded body 10 was 28 mm, and the maximum diameter in plan view was 70 mm. The raw material 50 of the molded body 10 was as shown in Table 1 below. The molding surface 32 of the upper collar 3 had an uneven shape, and the molding surface 42 of the lower collar 4 had a concave shape. The deepest part of the molding surface 42 of the lower collar 4 is a flat surface, and a part thereof corresponds to the upper end surface of the protruding core 5.

As the pusher 8, a pusher 8 a having a diameter of 35 mm was used. The shape of the pressing portion 8 a was substantially the same as the shape of the flat surface located at the deepest portion of the molding surface 42 of the lower collar 4. After the raw material 50 is filled by the feed shoe 7 into the molding space formed by the inner wall of the mortar 2 and the molding surface 42 of the lower arm 4, the pusher 8 is lowered at a speed of 50 mm / sec to press the raw material 50. Went. The pressure at the time of pressing was 203 kPa. The pusher 8 was held at its lowest position for 0.5 seconds. The pusher 8 was raised at the same speed as the descent speed. At the lowest lowered position of the pusher 8, the lower surface of the disk-shaped pressing portion 8a and the upper surface of the mortar 2 were in the same position. Next, after the raw material 50 was scraped off at the position of the upper surface of the mortar 2 by the feed shoe 7, the upper punch 3 was lowered to compress the raw material 50 in the molding space. The molding pressure was 16.87 MPa and the molding time was 2 seconds. After the completion of molding, the upper collar 3 was raised, the protruding core 5 was also raised, and the molded body 10 was taken out. The average density of the entire molded body 10 obtained was 1.31 g / cm ³ as a result of calculation from its dimensional value and weight.

[Comparative Example 1]
In Example 1, the pressing by the pusher 8 was not performed, and the compression molding by the lowering of the upper collar 3 was directly performed to obtain a molded body. The compression was performed by adjusting the molding pressure so as to be the same density as the density of the molded body obtained in Example 1.

[Evaluation]
The hardness of each part in the powder compression molding obtained in the examples and comparative examples was measured. The measurement was performed according to the following procedure. The molded body was cut along the horizontal direction using a milling machine to form a flat portion for hardness measurement. Cutting was performed at intervals of 2 mm along the thickness direction of the molded body. The hardness of the formed flat portion was measured with a micro rubber hardness meter MD-1 (manufactured by Kobunshi Keiki Co., Ltd., stylus φ0.16 mm, length 0.5 mm). The measurement positions were a total of 21 locations, 9 in the central area in plan view of the molded body and 12 in the peripheral area. The central region is a circular portion having a radius of 15 mm from the center of the molded body in plan view. The peripheral region is an annular portion having a radius in the range of 15 mm to 22.5 mm from the center of the molded body in plan view. The measurement results are shown in FIGS. 7 and 8, R represents the degree of hardness variation.

  As is apparent from the results shown in FIGS. 7 and 8, it can be seen that the molded body obtained in the example has less variation in hardness in the thickness direction and the planar direction than the molded body obtained in the comparative example. . Moreover, it turns out that the value of hardness itself is higher than the molded object obtained by the comparative example.

DESCRIPTION OF SYMBOLS 1 Powder compression molding apparatus 2 Mill 3 Upper punch 4 Lower punch 6 Tableting table 7 Feed shoe 8 Pusher 8a Press part 10 Powder compression molding 11 Lower part of powder compression molding 12 Upper part 21 of powder compression molding Surface 42 Molding surface

Claims (6)

A filling step of filling a molding space formed by a mortar and a molding surface of a lower jaw arranged in the mortar, a raw material containing powder, and lowering the upper jaw into the mortar, A method for producing a powder compression molded body comprising a molding step for compression molding,
As the lower iron, use the one that has a recess in its molding surface,
In the filling process, the powder that partially presses the upper part of the raw material filled in the molding space with the pusher having a shape smaller than the opening end shape of the mortar while filling the raw material in the molding space or after completion of filling. A method for producing a compression molded body.   The manufacturing method according to claim 1, wherein the raw material is pressed by lowering the pusher from a position higher than the upper surface of the mortar to the same position as the upper surface.   The manufacturing method according to claim 2, wherein, in the filling step, after pressing the raw material with a pusher, the raw material is scraped off at the position of the upper surface of the mortar.   The manufacturing method according to any one of claims 1 to 3, wherein the pressure when the raw material is pressed by the pusher is 0.1 to 20% of the molding pressure when the raw material is compression-molded by the upper punch. The deepest part of the recess on the molding surface of the lower arm is a substantially flat surface,
The manufacturing method as described in any one of Claims 1 thru | or 4 which uses the shape of the raw material press surface as a pusher as the outline shape in planar view of the said substantially flat surface.   The manufacturing method as described in any one of Claims 1 thru | or 5 which uses what the molding surface has an unevenness | corrugation as an upper collar.

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