pestle body

Abstract

To provide a pestle body that can effectively suppress metallic dust, which is generated mainly due to friction or the like of the pestle body, from mixing into a tablet or the like that is compression-molded by using the pestle body and a semiconductor substrate or the like to which sealing or the like is performed.SOLUTION: Pestle bodies are formed in a rod-like shape and respectively have pressing parts for pressing an article which is pressed against one end part thereof while contacting the article, pressurizing parts to which stress for pressing the article against the other end part is applied, and holding parts in which the pestle bodies are held slidably between the pressing parts and the pressurizing parts, which press an article by making the holding parts reciprocate in a longitudinal direction while holding the holding parts slidably, where magnets are arranged between the pressing parts and / or the pressurizing parts of the pestle bodies, and the holding parts.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a pestle body used for applying pressure to an object by reciprocating motion for the purpose of compressing powder into forms such as tablets and foods, or forming resin pellets used for injection molding, etc.

Background Art

[0002] Conventionally, a molding method has been used in which various powdery substances are compressed by applying pressure to form the powdery substances into solid objects having a predetermined shape. For example, in Patent Document 1, a powdery substance filled in a mortar hole is pressurized and compressed between an upper pestle and a lower pestle, which are rod-shaped pestle bodies provided so as to be vertically movable on the axis of the mortar hole provided in a plate-like body, and a powder compression molding apparatus for performing molding processing into a solid object having a predetermined shape is described.

[0003] On the other hand, Patent Document 2 describes a sealing device that seals a semiconductor substrate by pressing a sealing member against the semiconductor substrate placed on a mounting table using a vertically movable pressing member (pestle body).

[0004] In devices for molding an object by applying pressure as described in Patent Documents 1 and 2, mainly for the purpose of applying pressure to the object by a simple mechanism, a rod-shaped pestle body that is mainly held so as to be reciprocally movable up and down is used as a pressure applying means for performing the pressure application.

[0005] That is, in the powder compression molding apparatus described in Patent Document 1, in a state where the upper and lower pestle bodies are arranged so as to sandwich the powdery substance to be molded, the distance between the upper and lower pestle bodies is reduced by passing between compression rolls or the like arranged at a certain interval, thereby compressing the powdery substance to form tablets or the like. Also, in the sealing device described in Patent Document 2, the pestle body is driven by means that causes vertical movement such as an air cylinder, and the distance between the pestle body and the mounting table is reduced to seal the semiconductor substrate.

Prior Art Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-148321 [Patent Document 2] Japanese Patent Publication No. 2012-43898 [Patent Document 3] Japanese Patent Publication No. 2021-80907 [Patent Document 4] Japanese Patent Publication No. 2008-43858 [Overview of the project] [Problems that the invention aims to solve]

[0007] The punch used in the powder compression molding apparatus described in Patent Document 1 and the sealing apparatus described in Patent Document 2 is used to press against the object by applying stress in the direction of the reciprocating motion of the punch to the powder being compressed or the sealing member, thereby performing the desired molding or other process. On the other hand, the stress applied to the punch during molding is due to compression between compression rolls, etc. (Patent Document 1), and is not necessarily a stress in the direction of compressing the powder, but rather a stress with complex directional properties is applied to the punch. Generally, the punch is held slidably by a high-strength sheath (guide), thereby restricting the punch from moving in directions other than the predetermined reciprocating motion, and the stress in the direction of the punch's reciprocating motion is applied to the powder being compressed or the sealing member, etc. However, due to differences in the direction of stress applied to the punch and its direction of motion, a large frictional force is generated between the punch and the sheath in the configuration described above, and dust generation due to this friction is unavoidable. Similarly, friction exists between the punch and the compression rolls, and dust generation from these parts is unavoidable. Furthermore, there are concerns that if the dust generated by this friction is mixed into the compressed tablets or pellets, it could cause significant problems for the product. The present invention aims to provide a punch that can effectively suppress the incorporation of metallic dust, mainly generated by friction around the punch, into tablets and the like that are compression-molded using the punch, or into semiconductor substrates and the like that are sealed. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides the following means. (1) A punch having a rod shape, having a pressing portion at one end for contacting and pressing an article to be pressed, a pressurizing portion at the other end to which stress for pressing the article is applied, and a holding portion in which the punch body is slidably held between the pressing portion and the pressurizing portion, wherein the punch body is pressed by reciprocating motion in the longitudinal direction while the holding portion is slidably held, and a magnet is provided between the pressing portion and / or pressurizing portion of the punch body and the holding portion. (2) The magnet is provided between the pressing portion and the holding portion of the pestle body. (3) A punch body in which at least a portion of the punch body is made of a material that exhibits ferromagnetism. (4) The magnet is attached to the pestle body via an elastic body. (5) The above-mentioned elastic body is a punch made of a material that exhibits ferromagnetism. (6) A powder compression molding apparatus having the above-mentioned punch body. [Effects of the Invention]

[0009] According to the present invention, it is possible to effectively adsorb metallic dust generated as a result of the movement of the punch body, and to effectively suppress the inclusion of metallic dust in products that are compression molded or otherwise subjected to molding. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram shows an overview of the configuration of a powder compression molding apparatus. [Figure 2] This figure shows an overview of the powder compression molding process using a powder compression molding machine. [Figure 3]It is a diagram showing an overview of a powder compression molding apparatus having a pestle body according to the present invention. [Figure 4] It is a diagram showing an overview of the configuration of a powder compression molding apparatus. [Figure 5] It is a diagram showing an example of another configuration example of the pestle body according to the present invention. [Figure 6] It is a diagram showing an example of another configuration example of the pestle body according to the present invention. [Figure 7] It is a diagram showing an example of another configuration example of the pestle body according to the present invention. [Figure 8] It is a diagram showing an example of another configuration example of the pestle body according to the present invention.

Embodiments for Carrying Out the Invention

[0011] In FIG. 1, an example of the configuration of a part of a so-called tableting machine 1 in a powder compression molding apparatus generally used when forming tablets by compressing powder or forming resin pellets for injection molding or the like is schematically shown. In a general tableting machine 1, a mortar material 3 provided with a through hole having a predetermined inner diameter is inserted into a hole provided in a table 7, and the through hole provided in the mortar material 3 is used as a mortar hole when compressing and molding the powder 10, and molding such as tablets is performed.

[0012] That is, inside the through hole provided in the mortar material 3 so as to have a diameter corresponding to the tablets or the like to be molded, the tip portions of the upper pestle 2 and the lower pestle 2' are brought into contact with each other, and the powder 10 is compressed and molded into the shape of the space formed between the tip portions. The upper pestle 2 and the lower pestle 2' are generally cylindrical rod-shaped as a whole and axially symmetric, and the main body portion thereof is a cylinder having a diameter of about φ20 to 70 mm according to the size of the tablets to be molded. A pressing portion for pressing against the powder pressed inside the through hole provided in the mortar material 3 is formed at one end thereof, and the portion near the pressing portion has a diameter corresponding to the diameter of the through hole of the mortar material 3. The other end of the pestle body is a pressurizing portion for applying a stress for pressing an article from the outside, and is formed in a shape suitable for pressurization.

[0013] The upper pestle 2 and the lower pestle 2' are provided coaxially with the central axis of the through-hole provided in the mortar material 3 in a state where they can reciprocate respectively, and the tip portions of the upper pestle 2 and the lower pestle 2' are respectively arranged so as to be insertable into the through-hole by the reciprocating motion. And by making the diameters of the tip portions of the upper pestle 2 and the lower pestle 2' about 10 to 100 microns smaller than the inner diameter of the through-hole, the powder compressed and formed from the gap between the inner wall of the through-hole and the tip portions of the upper pestle 2 and the lower pestle 2' is prevented from leaking, and the friction with the inner surface of the through-hole is made difficult to occur when the upper pestle 2 and the lower pestle 2' are inserted into the through-hole.

[0014] The upper pestle 2 and the lower pestle 2' use the upper guide portion 4 and the lower guide portion 4' rigidly held by the upper holding mechanism 6 and the lower holding mechanism 6' respectively, and the cross-sectional shape between the pressing portion and the pressurizing portion of the pestle body is made constant. The portion of the holding portion is slidably held by the guide portion, so that it is possible to generate a reciprocating motion on a predetermined axis when an external force is applied. The range of the holding portion in the pestle body is determined according to the length of the corresponding guide portion and the stroke length of the reciprocating motion of each pestle body, and a pestle body having a length suitable for the tableting machine 1 using the pestle body is used. When in use, it is preferable that the portion of the holding portion of the pestle body sliding on the inner wall of the guide portion forms a predetermined interval with the pressing portion and the pressurizing portion. Note that the shape of the holding portions of the upper pestle 2 and the lower pestle 2' is not limited to a cylindrical shape, and it can be made to have an appropriate cross-sectional shape such as a quadrangular prism or a hexagonal prism.

[0015] In the tablet press 1 shown in Figure 1, large stresses are generated at the tips of the upper punch 2 and lower punch 2' in order to compress and mold the powder. At the same time, in order to insert the tips of the upper punch 2 and lower punch 2' into the through-holes in the die material 3, it is necessary to align the direction of movement of the upper punch 2 and lower punch 2' with the central axis of the through-holes with high precision. For this reason, by rigidly fixing the upper holding mechanism 6 and lower holding mechanism 6' to the table 7, the table 7, holding mechanisms 6, 6', and guide parts 4, 4' are made substantially integrated to prevent mutual displacement, so that the upper punch 2 and lower punch 2' can be inserted into the through-holes at their respective timings by a mechanism such as the one shown in Figure 2 below. Furthermore, from the viewpoint of providing high rigidity to each part of the tablet press 1, each part of the tablet press 1, including the punch body, is generally made of structural steel or the like.

[0016] The process of compressing and molding powder using a tablet press as shown in Figure 1 is configured as follows. First, the tip of the lower punch 2' is inserted into the through-hole of the die material 3, and with the tip of the lower punch 2' positioned at a predetermined depth from the upper surface of the die material 3, forming the bottom of the through-hole, the powder 10 to be compressed and molded is supplied to the surface of the die material 3 and table 7 near the through-hole by a feed shoe (powder supply device) (not shown), and a portion of it fills the through-hole.

[0017] Subsequently, a spatula (squeegee) or the like (not shown) is used to sweep the upper surfaces of the die material 3 and the table 7, removing any powder that was not filled into the through-holes from the upper surface of the table 7. At this time, the upper surface of the die material 3 and the surface of the table 7 form the same plane, which allows for effective sweeping of the powder with the spatula.

[0018] After the powder to be compressed is filled into the through-hole, the upper punch 2 is lowered and its tip is inserted into the through-hole to close it. In this state, the upper punch 2 is lowered and / or the lower punch 2' is raised to compress the powder 10 inside the through-hole, thereby performing compression molding. Subsequently, with the upper punch 2 raised to open the top of the through-hole, the lower punch 2' is raised, or air pressure is used, to remove the tablets or the like obtained by compression molding from the through-hole.

[0019] In a powder compression molding apparatus using a tablet press 1 as shown in Figure 1 above, for example, as described in Patent Document 1, multiple die materials 3, holding mechanisms 6, 6', guide parts 4, 4', upper punch 2, lower punch 2' are installed on the same circumference of a disc-shaped table 7, and by rotating the table 7, the upper punch 2, lower punch 2', etc. are operated by the force of the rotation to perform continuous compression molding of the powder.

[0020] Figure 2 schematically shows how the upper punch 2 and lower punch 2' are made to reciprocate in a predetermined pattern by passing the tablet press 1, as shown in Figure 1, between pre-positioned guide rails 9 and rotating rolls 8. In Figure 2, the horizontal direction corresponds to the linear unfolding of the rotational motion performed by the die material 3 fixed to the rotating disc-shaped table 7, and the horizontal axis corresponds to the rotation angle of the table 7 (the angle at which the die material 3 is located).

[0021] The mortar material 3, fixed to a rotating disc-shaped table 7, moves in a circular motion within a plane 12 perpendicular to the rotation axis of the table 7. The upper pestle 2 and lower pestle 2' corresponding to the mortar material 3 move together with the mortar material 3, with their central axes aligned with the central axis of a through hole provided in the mortar material 3.

[0022] Meanwhile, annular guide rails 9, 9' are provided above and below the table 7 to which the mortar material 3 is attached, and the distance between the mortar material 3 and the guide rails 9, 9' is set to change in a predetermined pattern depending on the position of the mortar material 3 on its circumference. The upper pestle 2 (lower pestle 2'), which is positioned above (below) the mortar material 3 and moves with it, is pushed downward (upward) as the distance between the mortar material 3 and the guide rail 9 narrows, and the tip of the upper pestle 2 (lower pestle 2') is inserted into the through hole of the mortar material 3, and the powder 10 filled inside the through hole is compressed.

[0023] The upper pestle 2 and lower pestle 2' are biased by springs or the like (not shown) so that their tips move away from the mortar 3, thereby increasing the distance between the mortar 3 and the guide rails 9, 9', and causing their pressing parts to move away from the mortar 3. Alternatively, the upper pestle 2 and lower pestle 2' can be slidably fixed to the guide rails 9, 9', allowing them to move up and down in accordance with changes in the distance between the guide rails 9, 9' and the mortar 3.

[0024] Furthermore, in particular, at positions where large stresses are applied to the upper punch 2 and lower punch 2', such as when completing the compression of the powder 10 filled inside the through hole, rotating rolls 8 and 8' are provided instead of guide rails 9 and 9' to eliminate the difficulty of movement (rotation) due to friction between the guide rails 9 and 9' and the upper punch 2 and lower punch 2'.

[0025] In other words, the distance between the annular guide rails 9,9' and the rotating rolls 8,8' and the surface 12 on which the die material 3 is located is set so that the tips of the upper punch 2 and lower punch 2' are in the desired position, depending on the purpose of filling the through-hole with powder 10, compressing the filled powder, and then opening the through-hole. Then, by rotating the table 7 at high speed, the tablet press 1, which is provided at multiple locations on the table 7, continuously compresses and molds the powder.

[0026] On the other hand, when powder was continuously compressed and molded using the tablet press 1 described above, it was observed that a certain proportion of the compressed tablets contained inclusions with properties that should not be present. When the inventors investigated the inclusions found in the compressed tablets, it became clear that the majority were powders mainly composed of metals and were attracted to magnets.

[0027] Therefore, the inventors of the present invention investigated various means of effectively collecting metal dust generated when compressing using a punch, etc., with a magnet, with the aim of suppressing the frequency with which the inclusions are incorporated into compacted bodies such as tablets that are compressed. As a result, the inventors arrived at the present invention. Furthermore, applying a magnet to oil or other substances containing metal chips to attract and remove them is an effective means of collecting metal dust, as described, for example, in Patent Documents 3 and 4.

[0028] Figures 3 and 4 show an example configuration for arranging magnets 20 around the compressed powder in a tablet press with the configuration shown in Figure 1. In the tablet press shown in Figure 1, the surfaces surrounding the compressed powder were considered to be (a) the lower surface of the holding mechanism 6 that holds the upper punch 2 (Figure 4(a)), (b) the table surface 7 to which the die material 3 is attached (Figure 4(b)), and (c) the surface of the punch body (upper punch 2) (Figure 3). Therefore, in the tablet press with the configuration shown in Figure 1, we attempted to collect metal dust when compression molding was repeated by attaching multiple small magnets 20 to each of the above positions, and searched for the magnet attachment positions that would enable effective collection of metal dust. As shown in Figures 3 and 4, the evaluation was performed by adsorbing the magnets 20 to each surface so that the line connecting the S / N poles of each magnet was approximately perpendicular to each attachment surface.

[0029] In the tablet press used in the above evaluation, the punch body and holding mechanism 6 are made of steel. Therefore, as shown in Figures 3 and 4, when magnets are attached to each surface, the punch body and holding mechanism 6 act as yoke materials, and it is thought that magnetic field lines are generated in the form shown in each figure. Thus, it is desirable for metal dust to be attracted to the magnetic pole (e.g., the north pole) exposed on the surface of the magnet, and it is also thought that the steel portion surrounding the magnetic pole functions as the other magnetic pole (e.g., the south pole), and metal dust is attracted to it in the same way.

[0030] As a result of the above evaluation, when the magnet 20 was attached to the lower surface of the holding mechanism 6 of the upper punch 2 (Figure 4(a)), metal dust was observed to be adsorbed onto the surface of the magnetic poles, etc. Also, when the magnet 20 was attached to the table surface 7 on which the die material 3 is attached (Figure 4(b)), metal dust was observed to be adsorbed onto the surface of the magnetic poles, etc., and it was observed that the adsorbed metal dust was mixed into the powder during the process of sweeping the powder that was to be filled into the through-holes of the die material 3 with a spatula (squeegee). Furthermore, as shown in Figure 4(b), even when the magnet 20 was embedded in the table surface 7 to avoid contact with the spatula, it was observed that the powder was filled into the recess that was formed, and that the metal dust was mixed into the powder by the movement of the spatula.

[0031] In contrast to the above, as shown in Figure 3, when a magnet 20 was attached to the side near the tip of the punch body (upper punch 2) exposed from the guide section 4 and the tablet-making operation was performed, it was observed that metal dust was attracted to the magnetic pole of the magnet and the surface of the punch body, and that the frequency of inclusion of impurities in the compacted powder was suppressed. Furthermore, it was observed that the amount of adsorption was improved compared to when the magnet was used in the configuration shown in Figure 4(a).

[0032] The causes of inclusions (metal dust) mixed into compacted powder formed by a tablet press, and the paths by which they enter the powder during compression, are not entirely clear. However, given that the metal dust is expected to be generated due to the sliding of machine parts, and that the frequency of inclusion is suppressed by the embodiment shown in Figure 3, the origin of the inclusions was inferred as follows.

[0033] In the tablet press evaluated above, the driving force for reciprocating the punches (upper punch 2, lower punch 2') is generally provided by means of narrowing the distance between the upper and lower punches using guide rails 9 and rotating rolls 8, as shown in Figure 2. When the punches are driven in the direction of narrowing the distance between them using these means, a stress is generated at the contact point between the guide rails 9 (rotating rolls 8) and the punches, with a direction perpendicular to the surface of the guide rails 9 (rotating rolls 8). The direction of this stress does not coincide with the direction of movement of the punches, and it is considered to include a component in the direction of movement of the punches (hereinafter, this stress component will be conveniently referred to as the "vertical component") as well as a component perpendicular to the direction of movement of the punches (hereinafter, this stress component will be conveniently referred to as the "horizontal component").

[0034] On the other hand, in order for the tip of the pestle to be accurately inserted into the through hole of the mortar material 3, displacement of the pestle due to the horizontal component stress generated between it and the guide rail 9, etc., is not permitted. Therefore, the horizontal component stress is supported by the rigid guide section 4, and the pestle is configured to be displaced substantially only in the direction of reciprocating motion due to the vertical component stress.

[0035] In order to suppress friction between the pestle body's holding part and the guide part 4, various bearing mechanisms are generally provided on the inner surface of the guide part, and lubrication is performed with lubricating oil, etc., so that the reciprocating motion of the pestle body is performed with the occurrence of friction between the guide part 4 and the pestle body caused by the horizontal component stress suppressed. On the other hand, friction still occurs between the guide part 4 and the pestle body's holding part due to the horizontal component stress, and as the pestle body repeatedly reciprocates at high speed, microscopic wear occurs between the guide part 4 and the pestle body's holding part. It is thought that the metal dust generated by this wear adheres to the surface of the pestle body and is released as metal dust 11 to the outside of the contact part with the guide part 4, and is the main cause of inclusion of inclusions in the compacted powder.

[0036] In response to the dust generation described above, as shown in Figure 3, by providing a magnet 20 on the surface between the holding part and the pressing part of the punch body (upper punch 2) that presses the powder, the magnetic field formed by the magnet 20 is distributed along the path in which the metal dust 11 diffuses toward the die material 3. This increases the rate at which the metal dust 11 is captured, and it is considered that the inclusion of the metal dust 11 as an inclusion in the compacted powder can be effectively suppressed. It is also considered that a good powder compression molding apparatus can be constructed by using a punch body having this configuration. In particular, by attaching the magnet 20 near the holding part of the punch body in a range where the magnet 20 does not come into contact with the guide part 4 when the upper punch 2 rises, the frequency of capturing the metal dust 11 generated between the guide part 4 and the punch body can be increased.

[0037] Furthermore, by attaching the magnet 20 to a ferromagnetic punch in the configuration shown in Figure 3, the punch is thought to act as a yoke, causing magnetic field lines to appear on the surface of the punch around the magnet 20. This allows the surface of the punch to act as a magnetic pole, attracting metal dust 11 before it diffuses into the air, thus suppressing the mixing of metal dust 11 into compacted powder and the like. Figure 3 shows an example in which a magnet 20 is provided on the surface of the punch between the pressing portion 2A and the holding portion 2B held by the guide portion 4. However, since the metal dust 11 generated as described above can also be generated from the upper end of the guide portion 4, the metal dust 11 can also be effectively attracted by providing a magnet 20 on the surface of the punch between the holding portion 2B and the pressurizing portion 2C that contacts the guide rail 9, etc., thereby suppressing the generation of metal dust 11 around the tablet press.

[0038] The pestle body that constitutes the pestle body according to the present invention can be made of a material that has the mechanical properties required for a pestle body, such as steel or stainless steel, which are generally used as structural members. In particular, by applying the present invention to a pestle body made of a ferromagnetic material such as steel or 400 series stainless steel (for example, Sus403), it becomes easier to attach the magnet 20 to the pestle body, and by using the pestle body as a yoke material, it becomes possible to efficiently capture metal dust.

[0039] On the other hand, even when using a punch made of 300 series stainless steel such as Sus304, which exhibits non-magnetic properties, the metal dust generated from the non-magnetic stainless steel by mechanical action generally exhibits ferromagnetism. Therefore, by applying the present invention as a means of capturing metal dust, it is possible to capture the metal dust and suppress its incorporation into compacted powder, etc.

[0040] Figure 5 shows an example of a configuration for attracting metal dust 11 by attaching a magnet 20 to a ferromagnetic punch (upper punch 2). In the configuration shown in Figure 3, the line connecting the N pole and S pole inside the magnet 20 is positioned approximately perpendicular to the direction of the reciprocating motion of the punch 2, and the punch 2 constitutes a yoke for one of the magnetic poles of the magnet 20. In contrast, as shown in Figure 5(a), a yoke 23 made of a ferromagnetic material is added to the back side of the magnet 20, and the yoke 23 and the punch 2 are positioned opposite each other. This concentrates the magnetic field lines emitted by the magnet 20 at the point where the yoke 23 and the punch 2 oppose each other, making it possible to effectively capture metal dust generated by the sliding of the guide part 4 and the punch 2.

[0041] On the other hand, as shown in Figure 5(b), by attaching the magnet 20 to the punch body 2 such that the line connecting the N pole and S pole inside the magnet 20 is approximately parallel to the direction of the reciprocating motion of the punch body 2, it becomes possible to capture metal dust on the surfaces of both poles of the magnet 20, and by expanding the adsorption surface, it becomes possible to capture a large amount of metal dust.

[0042] Figure 6 shows examples of other configurations for attracting metal dust 11 by attaching a magnet 20 to a ferromagnetic or non-magnetic punch. In a tablet press like the one shown in Figure 1, high-speed compression molding of powder is generally performed to improve productivity. Depending on the type of powder to be compressed, operations such as applying impact pressure with the punch are performed to obtain a good compacted powder.

[0043] On the other hand, magnets, including Fe-Nd magnets and rare-earth magnets such as Sm-Co magnets, which are known to generate particularly strong magnetic fields, are generally brittle, and there is a concern that they may develop internal cracks and collapse if subjected to high-frequency, long-term impact acceleration. In particular, when the magnet 20 is attached to the punch body by means such as being fitted into it, as shown in Figure 3, the acceleration generated in the punch body is directly transmitted to the magnet, and it is anticipated that the magnet 20 may break during long-term use.

[0044] In contrast to the above, in the configuration shown in Figure 6, the magnet 20 is attached to the pestle body via an elastic metal material (non-magnetic material) 22. Figure 6(a) shows a donut-shaped metal material 22 having a hole in the center with a diameter corresponding to the pestle body 2, with multiple magnets fixed to its surface, and the pestle body 2 being fixed near the tip of the pestle body 2 with the pestle body 2 passing through the hole in the metal material 22. With this configuration, even under conditions where the pestle body is subjected to strong acceleration during powder compaction, the elastic metal material 22 is interposed between the pestle body and the magnet 20, which mitigates the acceleration generated in the magnet 20 and reduces the frequency of the magnet 20 collapsing.

[0045] In particular, in the configuration shown in Figure 6, the elastic metal material 22 is made from a non-magnetic material such as titanium or Sus304, and the line connecting the N pole and S pole inside the magnet 20 is arranged to be approximately parallel to the direction of the reciprocating motion of the punch body 2. As a result, even when the magnet 20 is held by the metal material 22, the same magnetic field distribution as when the magnet 20 is directly attached to the punch body is obtained, as shown in Figure 5(b), and metal dust can be captured on the upper surface of the magnet 20 and on the surface of the metal material 22 near the lower surface of the magnet 20. In addition, as the elastic material used to hold the magnet 20, it is also possible to use a resin or the like with a predetermined strength.

[0046] As shown in Figure 6, when holding the magnet 20 with a metal material acting as an elastic body, it is preferable to set the material, thickness, and structure of the components constituting the metal material so that the amount of deformation in the metal material falls within the range of elastic deformation of the metal material, taking into consideration the weight of the magnet 20 used and the acceleration generated in the punch body during compaction. For example, as shown in Figure 6(b), by giving the metal material 22 that holds the magnet 20 a predetermined cross-sectional shape, it is possible to reduce the acceleration generated in the magnet 20 while suppressing the concentration of deformation inside the metal material 22. While there are no particular limitations on the structure for attaching a metal plate or the like to the pestle body, which is used as an elastic body to hold the magnet 20, the metal material 22 can be fixed to the part of the pestle body where the diameter changes, for example, as shown in Figure 6, by an appropriate fitting structure, screw fastening, etc.

[0047] Figure 7 shows an example of another configuration for attracting metal dust 11 by attaching a magnet 20 to a ferromagnetic punch (upper punch 2). The configuration shown in Figure 7(a) is characterized in that, compared to Figure 6(a), a ferromagnetic metal material 21 is used instead of a non-magnetic metal material 22 as an elastic body for holding and attaching the magnet 20 to the punch. As shown in Figure 7, by holding the magnet 20 to the punch using the ferromagnetic metal material 21, the metal material 21 functions as a yoke material, making it possible to concentrate the magnetic field lines generated from the magnetic pole of the magnet 20 on the side in contact with the metal material 21 at an appropriate position.

[0048] In particular, when the pestle body 2 is made of a ferromagnetic metal such as steel, it is possible to guide magnetic field lines to the pestle body via the metal material 21. By using the configuration shown in Figure 7(a), the magnetic field generated by the magnet 20 is concentrated between the upper surface of the magnet 20 and the surface of the pestle body in its vicinity, making it possible to efficiently capture metal dust generated between the guide part 4 and the pestle body 2. Furthermore, as shown in Figure 7(b), by providing a yoke material 23 on the upper surface of the magnet 20 and reducing the gap with the pestle body, the magnetic field lines emitted by the magnet 20 are concentrated in a narrow space, making it possible to capture metal dust with a strong magnetic force.

[0049] Furthermore, in the configuration shown in Figure 7, the magnetic field emitted by the magnet 20 is shielded by the metal material 21, which suppresses the distribution of magnetic field lines, particularly downwards from the magnet 20. This prevents, for example, powder supply devices and squeegees used when filling the die cavity with powder 10 from being affected by the magnetic force of the magnet 20.

[0050] In the configurations shown in Figures 7(a) and 7(b), by using an elastic body with a box-shaped cross-section to hold the magnet 20, for example as shown in Figure 6(b), within the range where the N and S poles of the magnet 20 are not magnetically short-circuited, the elastic body can be strengthened, and direct adhesion of metal dust to the magnet 20 can be prevented.

[0051] Figure 8 shows an example of another configuration for attaching a magnet 20 to a pestle (upper pestle 2) to attract metal dust 11. Figure 8 shows an example in which a ferromagnetic metal material 21 having a structure similar to that of Figure 7(a) is used to hold the magnet 20, particularly for a pestle 2" that is nonmagnetic. When a pestle 2" made of a nonmagnetic material is used, the influence on the distribution of magnetic field lines emitted from the magnet 20 is small, so it is thought that the magnetic field lines emitted from the upper surface of the magnet 20 directly reach the upper surface of the metal material 21, etc. Therefore, the upper surface of the metal material 21 acts as a magnetic pole, making it possible to efficiently capture metal dust generated between the guide part 4 and the pestle 2, etc., in the space between the magnet and the pestle.

[0052] Furthermore, as shown in Figure 7, even when a magnet 20 is held by a ferromagnetic punch 2 via a metal material 21, for example, a member with low magnetic permeability can be placed between the punch 2 and the metal material 21, or the punch can be constructed from a combination of multiple ferromagnetic or nonmagnetic members, and the magnetic flux distribution around the punch 2 and the metal material 21 can be adjusted depending on the method of combination.

[0053] Furthermore, by attaching the magnet 20 near the guide section 4 in a manner that prevents the magnet 20 from contacting the guide section 4 when the upper punch 2 rises, the sliding portion (holding portion) of the guide section 4 and the punch body 2 can be substantially enclosed by the magnet 20 and metal material 21, thereby preventing metal dust 11 generated between the guide section 4 and the punch body from spreading into the surroundings.

[0054] Furthermore, as shown in Figure 8, by covering the top of the magnet 20 with a flexible resin member 24, the magnet 20 can be protected from mechanical impact without affecting the elastic deformability or magnetic field distribution of the metal material 21. In addition, by partitioning the space between the guide part 4 and the resin member 24 with a bellows-shaped sleeve made of resin or the like, it is possible to further prevent metal dust 11 generated between the guide part 4 and the punch body from spreading into the surroundings.

[0055] The magnet 20 used to form a magnetic field around the above-mentioned punch body can be used without particular restrictions as long as it generates a magnetic force sufficient to attract metal dust. On the other hand, it is desirable to use a permanent magnet that can form a strong magnetic field, such as a rare-earth magnet, as a strong magnetic force generated by the magnet 20 allows for efficient capture of metal dust. In particular, by attaching the magnet to the punch body via an elastic material such as a metal plate, the acceleration applied from the punch body to the magnet 20 is mitigated, making it possible to use brittle magnets such as rare earth magnets.

[0056] The form of the magnet used in the present invention is not particularly limited. One or more magnets having a cylindrical shape or the like, with planar north and south poles formed substantially parallel to each other, may be used. It is also possible to magnetically connect these multiple magnets with a yoke material to use them as a single magnet. Furthermore, depending on how the magnet is attached to the punch body, it is also possible to use, for example, an annular magnet with a rectangular cross-section that has a radial magnetic field inside the magnet, or that has north and south poles on both planes.

[0057] The punch body according to the present invention can be formed, for example, by attaching a magnet in a predetermined form to a punch body (upper punch 2) attached to a tablet press, as shown in Figure 1, at an appropriate position on the punch body. When attaching the magnet to the punch body, for example, the magnet 20 can be attached to the punch body by the magnetic force of the magnet, as shown in Figure 3, or by providing a recess or the like on the surface of the punch body that matches the shape of the magnet 20, so that the magnet is less likely to come off due to the impact during the reciprocating motion of the punch body.

[0058] Furthermore, when providing a yoke material 23 around a magnet 20 attached to a punch body in the configuration shown in Figure 5(a), the magnet 20 can be prevented from coming off by using an annular yoke material 23 to restrain multiple magnets.

[0059] On the other hand, as shown in Figures 6 and 7, when attaching the magnet 20 to the pestle body via an elastic member such as a metal plate, the magnet 20 can be attached to the elastic member by magnetic force, adhesive, mechanical fitting, etc., and the pestle body and the elastic member can be fastened together using commonly used mechanical fastening means such as fitting or screwing.

[0060] In the above, we have mainly described a punch used in a tablet press (powder compression molding device) as shown in Figure 1, etc., but the applications of the present invention are not limited to this, and the present invention can be applied to punches that perform a similar reciprocating motion. For example, even in devices used for sealing semiconductor substrates, as described in Patent Document 2, it is possible to capture metal dust generated during operation by using the punch according to the present invention. Furthermore, the embodiments of the present invention are not limited to the forms described above, and the present invention can also be implemented in forms in which the technical elements included in each embodiment are appropriately substituted, as long as the effects of the present invention are not hindered. [Industrial applicability]

[0061] The present invention can be widely used in various processing devices that use a reciprocating punch, such as powder compression molding machines, and can suppress metal dust from being mixed into the workpiece. [Explanation of Symbols]

[0062] 1 Tablet press 2,2' pestle 3 Mortar wood 4,4' Guide section 6,6' retention mechanism 7 tables 8.8' Rotation Roll 9.9' Guide rail 10 powder 20 magnets 21 Metal materials (ferromagnetic materials) 22 Metal materials (non-magnetic materials) 23 Yoke material 24 Resin components

Claims

1. A rod-shaped punch having a pressing portion at one end for contacting and pressing an article to be pressed, a pressurizing portion at the other end to which stress for pressing the article is applied, and a holding portion in which the punch body is slidably held between the pressing portion and the pressurizing portion, wherein the punch body presses an article by reciprocating motion in the longitudinal direction while the holding portion is slidably held, A punching body characterized by having a magnet provided between the pressing portion and the holding portion of the punching body.

2. The punch body according to claim 1, characterized in that at least a portion of the punch body is made of a material that exhibits ferromagnetism.

3. The above-mentioned magnet is provided on the punch body via an elastic body, as described in claim 1 or claim 2.

4. The punch body according to claim 3, characterized in that the elastic body is made of a material that exhibits ferromagnetism.

5. A powder compression molding apparatus characterized by having a punch body as described in any one of claims 1 to 4.

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