JP4446900B2 - Filter mold - Google Patents

Description

  The present invention relates to a filter mold used when a cylindrical filter is molded from a resin material.

Conventionally, for example, a resin cylindrical filter is used when filtering oil circulating inside a power machine or the like (see, for example, Patent Document 1). The filter includes a side wall and a bottom wall. The side wall includes a plurality of first linear portions extending linearly in the direction of the center line of the filter and arranged in parallel at substantially equal intervals in the circumferential direction. A plurality of second linear portions extending annularly so as to surround the shape portion from the outside are formed integrally with the first linear portion and arranged in parallel at substantially equal intervals in the center line direction. These two linear portions form a large number of small holes for fluid filtration on the side wall of the filter. A large number of small holes for fluid filtration are also formed in the bottom wall of the filter.
Japanese Utility Model Publication No. 60-31319 (FIGS. 3 and 4)

  However, since the side wall of the filter of Patent Document 1 is composed of the first linear part and the second linear part surrounding the outside as described above, both linear parts are inward and outward of the filter. An overlapping portion is generated, and in the portion where the two linear portions overlap, the thickness becomes unnecessarily thick. When the thickness of the side wall is increased in this way, the outer shape of the filter expands, requiring a large space for disposing the filter, and the weight of the filter increases due to the material constituting the thick wall portion. And the material cost increases.

  The present invention has been made in view of such points, and the object of the present invention is to form a cylindrical filter having a large number of small holes for fluid filtration on each of the side wall and the bottom wall with a resin material. In addition, it is intended to reduce the size and weight of the filter and reduce the material cost by avoiding the occurrence of thickened portions on the side wall and the bottom wall.

  To achieve the above object, according to the first aspect of the present invention, there is provided a filter used when a bottomed cylindrical filter having a plurality of small holes for fluid filtration formed on each of a side wall and a bottom wall is molded from a resin material. A first outer side having a side wall molding surface for molding the side wall inner surface and the bottom wall inner surface of the filter, and an inner mold having a side wall molding surface for molding the outer side wall of the filter. A mold and a second outer mold having a bottom wall molding surface that molds the outer surface of the bottom wall of the filter, wherein the first outer mold has a predetermined width of about 1/4 or less continuous in the circumferential direction of the outer surface of the side wall. Each of the predetermined area forming molds is divided into a plurality of predetermined area forming molds for forming the areas, and the predetermined outer area forming molds move toward and away from the inner mold in the thickness direction of the side wall, and the second outer mold and the inner mold are separated from each other. Move relative to the thickness direction of the bottom wall Thus, the inner mold, the first outer mold, and the second outer mold are switched between a mold closed state in which a cavity is formed and a mold open state in which a filter molded in the cavity can be removed. On the side wall molding surface of the area molding die, there are a large number of pins that protrude in the moving direction of the predetermined area molding die, and whose tips are in a closed state to contact the side wall molding surface of the inner mold to mold the small holes in the side wall. One bottom wall molding surface of the second outer mold bottom wall molding surface and the inner mold bottom wall molding surface protrudes in the relative movement direction of the second outer mold and the inner mold, and the tip is In the mold-closed state, a plurality of pins that stand against the other bottom wall molding surface and mold small holes in the bottom wall are provided upright.

  According to the first aspect of the present invention, when the cavity is formed with the inner mold, the first outer mold, and the second outer mold closed, the pins of each predetermined area molding die abut on the side wall molding surface of the inner mold. At the same time, one pin of the second outer mold and the inner mold contacts the other bottom wall molding surface. The resin material supplied to the cavity spreads between the pins and can be demolded after solidification. When the mold is removed, the pins of the predetermined area mold extend in the moving direction of the predetermined area mold, and one pin of the second outer mold and the inner mold is in the relative moving direction of the second outer mold and the inner mold. Therefore, an undercut portion is not formed between these pins and the intermediate molded product of the molded filter. Accordingly, the inner mold, the first outer mold, and the second outer mold can be easily opened to obtain a filter in which small holes are formed in the traces of the pins.

  For example, when molding a cylindrical filter, the standing direction of the pin located in the middle portion in the circumferential direction on the side wall molding surface of each predetermined area molding die is such that the predetermined area molding die is in the thickness direction of the side wall. Since it moves, it will be the direction which penetrates this side wall. Furthermore, since the length in the circumferential direction of the side wall molding surface in each predetermined region molding die is shortened to about 1/4 or less of the outer surface of the side wall, the standing direction of the pins located on both sides in the circumferential direction is also reduced. It becomes the direction which penetrates a side wall. By these things, the small hole which penetrates a side wall can be formed in the wide range of this side wall. Further, a small hole penetrating in the center line direction of the filter can be formed on the bottom wall of the filter by a pin.

  Therefore, a large number of small holes can be formed in the side wall and the bottom wall without forming a portion where the first linear portion and the second linear portion overlap in the side wall and the bottom wall as in the prior art. Can be smoothly circulated in the inner and outer directions of the filter. Since the portion where the wall thickness is unnecessarily thick is eliminated on the side wall and the bottom wall of the filter, the filter can be reduced in size, and the space for disposing the filter can be reduced. In addition to reducing the weight of the filter, the material cost can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a filter mold 1 according to an embodiment of the present invention, and FIG. 2 shows a filter 3 molded by the mold 1. In the description of this embodiment, the structure of the filter 3 will be described before the structure of the mold 1 is described.

  The filter 3 is disposed, for example, in an oil pan (not shown) provided in an automobile engine. As shown in FIG. 3, the inside of an L-shaped pipe member 5 made of a resin material. Built in. Openings 5a and 5b are formed at one end and the other end of the pipe member 5, respectively, and a flange 7 extending outward is integrally formed at the periphery of the one end opening 5a. It can be attached. A substantially rectangular hole 5c is formed in the peripheral wall of the pipe member 5 close to the other end opening 5b.

  As shown in FIG. 2, the filter 3 has a cylindrical shape including a side wall 11 and a bottom wall 13, and an opening 3 a is formed at the end of the side wall 11 opposite to the bottom wall 13. Yes. The side wall 11 and the bottom wall 13 are integrally formed of a resin material. An annular extending portion 15 that extends outward is integrally formed on the periphery of the opening 3 a of the side wall 11. On the side wall 11 of the filter 3, a reinforcing first protrusion 17 projecting radially outward and extending over both ends of the center line direction of the filter 3, and the first protrusion 17 from the radially opposite side of the first protrusion 17. A reinforcing second ridge 19 projecting in the same manner as the first ridge 17 is formed. In the vicinity of the extension 15 of the first protrusion 17 and the second protrusion 19, a protrusion 20 that protrudes outward from the side wall 11 is integrally formed.

  The portions of the side wall 11 other than the first ridges 17 and the second ridges 19 are formed in a fine grid, and as shown in FIG. A hole 21 is formed. Similarly, a small hole (not shown) is formed in the bottom wall 13, and the shape of the side wall 11 and the small hole 21 of the bottom wall 13 is substantially rectangular in plan view.

  When the filter 3 is inserted into the other end opening 5b of the pipe member 5 from the bottom wall 13 side and is completely inserted into the pipe member 5, as shown in FIG. Comes into contact with the peripheral edge of the other end opening 5 b of the pipe member 5, and at this time, the protrusion 20 of the filter 3 is fitted into the hole 5 c of the pipe member 5 and the filter 3 is held in the pipe member 5.

  Next, the structure of the filter mold 1 will be described. The mold 1 is attached to an injection molding machine (not shown). As shown in FIGS. 1 and 5, an inner mold 31 that molds the inner surface of the filter 3 and an outer surface of the side wall 11 of the filter 3 are molded. And a second outer mold 35 that molds the outer surface of the bottom wall 13 of the filter 3. In this embodiment, for convenience of explanation, a case will be described in which the filter 3 is molded with its center line oriented in a substantially horizontal direction.

  The inner mold 31 is formed in a substantially cylindrical shape, and as shown in FIG. 5, a side wall molding surface 31 a for molding the inner surface of the side wall 11 of the filter 3 and a bottom wall molding surface for molding the inner surface of the bottom wall 13 of the filter 3. 31b. The side wall molding surface 31a is a circular surface, and the bottom wall molding surface 31b is a flat surface. The inner mold 31 is moved toward and away from the second outer mold 35 by moving the inner mold 31 in the center line direction (the direction indicated by the arrow e in FIG. 5) on the end surface opposite to the bottom wall molding surface 31b of the inner mold 31. An inner mold moving mechanism (not shown) is connected.

  As shown in FIG. 1, the first outer mold 33 is formed into first to fourth predetermined area forming molds 37 to 40 that respectively mold approximately 1/4 predetermined areas continuous in the circumferential direction of the outer surface of the side wall 11. It is divided. The first predetermined region molding die 37 is a first side wall molding surface 37a that molds a first region located on the left side and the upper side of the outer surface of the side wall 11 in a state where the filter 3 is arranged so that the center line thereof is oriented substantially in the horizontal direction. have. In this first predetermined area molding die 37, the molding die 37 is moved in a direction inclined in the upper left direction by approximately 45 ° with respect to the horizontal plane in the radial direction of the inner die 31 (the direction indicated by the arrow a in FIGS. 1 and 5). A first moving mechanism (not shown) is connected. By this first moving mechanism, the first predetermined region forming die 37 moves in the thickness direction of the side wall 3 and comes in contact with and separates from the inner die 31.

  In FIG. 1, the 1st concave surface 37b which shape | molds the upper half part of the said 1st protrusion 17 is formed in the lower end part of the said 1st side wall shaping | molding surface 37a. As shown in FIG. 6, a large number of first pins 45 are erected in the moving direction a by the first moving mechanism at portions other than the first concave surface 37 b of the first side wall forming surface 37 a. These first pins 45 are for forming the small holes 21 in the first region of the side wall 11 and are arranged at substantially equal intervals. The cross-sectional shape of the first pin 45 is substantially rectangular, and the base end side is held in a state of being embedded in the first side wall molding surface 37a. The projecting dimension of the first pin 45 from the first side wall molding surface 37 a is substantially the same as the thickness of the side wall 11, and its tip is formed so as to contact the side wall molding surface 31 a of the inner mold 31.

  Further, the second predetermined area forming die 38 is a second side wall forming that forms a second area located on the right side and the upper side of the outer surface of the side wall 11 in a state where the filter 3 is arranged so that the center line thereof is oriented substantially in the horizontal direction. It has a surface 38a. The second predetermined area molding die 38 is a second one in which the molding die 38 is moved in a direction (indicated by an arrow b in FIG. 1) inclined at an upper right angle of approximately 45 ° with respect to the horizontal plane in the radial direction of the inner die 31. A moving mechanism (not shown) is connected. By this second moving mechanism, the second predetermined area forming die 38 moves in the thickness direction of the side wall 3 and contacts and separates from the inner die 31.

  A second concave surface 38b for molding the upper half of the second protrusion 19 is formed at the lower end of the second side wall forming surface 38a. Similar to the first pin 45, a number of second pins 46 are erected in the moving direction b by the second moving mechanism at portions other than the second concave surface 38 b of the second side wall molding surface 38 a.

  The third predetermined region forming die 39 forms a third predetermined region located on the right side and the lower side of the outer surface of the side wall 11 in a state where the filter 3 is disposed so that the center line thereof is oriented substantially in the horizontal direction. It has a side wall molding surface 39a. In this third predetermined region molding die 39, the molding die 39 is inclined in the direction inclined by about 45 ° to the lower right with respect to the horizontal plane in the radial direction of the inner die 31 (the direction indicated by the arrow c in FIGS. 1 and 5). A third moving mechanism (not shown) to be moved is connected. By this third moving mechanism, the third predetermined area forming die 39 moves in the thickness direction of the side wall 3 and comes in contact with and separates from the inner die 31.

  A third concave surface 39b for molding the lower half portion of the second protrusion 19 is formed at the upper end of the third side wall forming surface 39a. Similar to the first pin 45, a large number of third pins 47 are erected in the moving direction c by the third moving mechanism at portions other than the third concave surface 39b of the third side wall forming surface 39a.

  Further, the fourth predetermined region forming die 40 is a fourth predetermined region forming the fourth predetermined region located on the left side and the lower side of the outer surface of the side wall 11 in a state where the filter 3 is disposed so that the center line thereof is oriented substantially in the horizontal direction. It has a side wall molding surface 40a. The fourth predetermined region molding die 40 has a fourth movement for moving the molding die 40 in a direction (indicated by an arrow d in FIG. 1) inclined to the lower left about 45 ° with respect to the horizontal plane in the radial direction of the inner die 31. A mechanism (not shown) is connected. The fourth predetermined region forming die 40 is moved in the thickness direction of the side wall 3 by this fourth moving mechanism and is brought into contact with and separated from the inner die 31.

  A fourth concave surface 40b for molding the lower half of the first protrusion 17 is formed at the upper end of the fourth side wall forming surface 40a. Similar to the first pin 45, a large number of fourth pins 48 are erected in the moving direction d by the fourth moving mechanism at portions other than the fourth concave surface 40b of the fourth side wall forming surface 40a. The first to fourth side wall molding surfaces 37a, 38a, 39a, and 40a constitute the side wall molding surface of the first outer mold 33 of the present invention.

  On the other hand, the second outer mold 35 is a fixed mold fixed to the base of the injection molding machine, and includes a bottom wall molding surface 35a for molding the outer surface of the bottom wall 13 of the filter 3 as shown in FIG. A number of bottom wall side pins 49 are erected on the bottom wall molding surface 35 a in the direction of the center line of the inner mold 31. That is, the standing direction of the bottom wall side pin 49 and the moving direction e of the inner mold 31 coincide. The bottom wall side pin 49 is for forming a small hole in the bottom wall 13 and has substantially the same shape as the first pin 45. The protruding dimension of the bottom wall side pin 49 from the bottom wall molding surface 35 a is set to be substantially the same as the thickness of the bottom wall 13. The tip of the bottom wall side pin 49 is formed so as to contact the bottom wall forming surface 31 b of the inner mold 31.

  The first to fourth moving mechanisms are configured to operate substantially in synchronization. When the first to fourth predetermined area molding dies 37 to 40 are brought close to the inner mold 31 by the first to fourth moving mechanisms, the tips of the first to fourth pins 45 to 48 are the side wall molding surface of the inner mold 31. It contacts 31a. Furthermore, when the inner mold 31 is moved closer to the second outer mold 35 by the inner moving mechanism, the tip of the bottom wall side pin 49 comes into contact with the bottom wall molding surface 31 b of the inner mold 31. As a result, the inner mold 31, the first outer mold 33 and the second outer mold 35 are closed, and the inner mold 31, the first outer mold 33 and the second outer mold 35 form a cavity S.

  On the other hand, the first to fourth predetermined area molding dies 37 to 40 in the mold closed state are moved away from the inner mold 31 by the first to fourth moving mechanisms, and the inner mold 31 is moved by the inner mold moving mechanism. When moved in a direction away from the second outer mold 35, the inner mold 31, the first outer mold 33, and the second outer mold 35 are in the mold open state. In this mold open state, the filter 3 molded in the cavity S is held by the inner mold 31.

  Next, the case where the said filter 3 is shape | molded using the shaping | molding die 1 comprised as mentioned above is demonstrated. First, after the inner mold 31, the first outer mold 33 and the second outer mold 35 are closed, a molten resin material is injected into the cavity S from an injection molding machine and filled. The molten resin material is distributed between the first to fourth pins 45 to 48 and the bottom wall side pin 49, and is molded by the side wall molding surfaces 31a, 37a, 38a, 39a, 40a and the bottom wall molding surfaces 31b, 35a. Then, it is solidified and becomes an intermediate molded product of the filter 3.

  At this time, the first to fourth pins 45 to 48 are erected in the moving directions a to d of the first to fourth predetermined region forming dies 37 to 40, and the bottom wall side pin 49 is moved to the inner die 31. Since e is erected, an undercut portion is not formed between the first to fourth pins 45 to 48 and the bottom wall side pin 49 and the intermediate molded product of the filter 3. Accordingly, when the mold is opened (demolded), the first to fourth predetermined area molding dies 37 to 40 are moved with respect to the inner mold 31, and the inner mold 31 is moved with respect to the second outer mold 35. The inner mold 31, the first outer mold 33, and the second outer mold 35 can be easily opened. After the mold is opened, when the intermediate molded product of the filter 3 held by the inner mold 31 is removed from the inner mold 31, the first to fourth pins 45 to 48 and the bottom wall side pin 49 are traced. The filter 3 in which the small holes 21 are formed is obtained.

  In addition, since the first predetermined region molding die 37 moves in the thickness direction of the side wall 11, the upright direction of the first pin 45 located in the middle portion in the circumferential direction in the first side wall molding surface 37a is The direction penetrates the side wall 11. Further, the length in the circumferential direction of the first side wall molding surface 37a in the first predetermined region molding die 37 is set to be approximately ¼ of the outer surface of the side wall 11, so that the first side wall molding surface 37a is located on both sides in the circumferential direction. The standing direction of the 1 pin 45 is a direction penetrating the side wall 11. Further, the small holes 21 are formed in the side wall 11 by the second to third pins 46 to 48 in the same manner as the first pin 45. By these things, the small hole 21 which penetrates the side wall 11 can be formed in the wide range of this side wall 11. Further, a small hole penetrating in the center line direction of the filter 3 is formed in the bottom wall 13 of the filter 3 by the bottom wall side pin 49.

  Therefore, according to the filter molding die 1 according to this embodiment, the first and second linear portions overlap each other without forming the overlapping portions on the side wall 11 and the bottom wall 13 as in the prior art. 11 and the bottom wall 13 can be formed with a large number of small holes 21 so that the oil can smoothly flow in and out of the filter 3. Thus, since the part where the thickness is unnecessarily thickened is eliminated from the side wall 11 and the bottom wall 13, the filter 3 can be reduced in size, and the space in the oil pan required for disposing the filter 3 can be reduced. In addition, the amount of resin material used can be reduced, the filter 3 can be reduced in weight, and the material cost can be reduced.

  Moreover, although this embodiment demonstrated the case where the cylindrical filter 3 was shape | molded, this invention is applicable also when shape | molding the cylindrical filter 3 whose cross-sectional shape is substantially square. That is, as shown in FIG. 7, the filter 3 has a bottom wall 13 formed in a substantially square shape, and the side wall 11 is configured by combining four rectangular portions 11 a that are long in the center line direction of the filter 3. These rectangular portions 11a have substantially the same shape. The extension 15 of the filter 3 is formed in a substantially rectangular shape when viewed from the front. Reference numeral 51 denotes a reinforcing frame, which is formed integrally with the side wall 11 and the bottom wall 13.

  Although not shown, the inner mold of the mold for molding the filter 3 is formed in a quadrangular prism shape. In addition, the first outer mold is divided into first to fourth predetermined area molding molds that mold the outer surfaces of the four rectangular portions 11a of the side wall 11 as first to fourth areas, respectively. That is, each of the first to fourth predetermined area forming dies is for forming a substantially ¼ area continuous in the circumferential direction of the outer surface of the side wall 11. Further, the side wall forming surfaces of the first to fourth predetermined area forming dies are formed substantially flat corresponding to the shape of each area of the side wall 11. Each of the first to fourth predetermined area forming dies is moved in a direction substantially orthogonal to the first to fourth areas by the first to fourth moving mechanisms to come in contact with and separate from the inner mold.

  A number of first pins are erected in the moving direction of the first moving mechanism on the first side wall forming surface of the first predetermined region forming die. Similarly, second to fourth pins are erected on the second to fourth side wall molding surfaces. Further, a bottom wall side pin is erected on the second outer mold.

  Accordingly, in this case as well, portions where the wall thickness is unnecessarily thick are eliminated from the side wall 11 and the bottom wall 13, so that the space in the oil pan required for disposing the filter 3 can be reduced, and the filter 3 can be reduced in weight, and the material cost can be reduced.

  In this embodiment, the case where the bottom wall side pin 49 is erected on the bottom wall molding surface 35 a of the second outer mold 35 has been described. However, the bottom wall side pin 49 is formed on the bottom wall molding surface 31 b of the inner mold 31. You may stand upright.

  Although not shown in the drawings, when a region exceeding 1/4 of the outer surface of the cylindrical side wall 11 is formed by each predetermined region molding die, all of the pins on the sidewall molding surface in the predetermined region molding die are the Since the pins are erected in the moving direction of the mold, the pins located on both sides in the circumferential direction of the side wall forming surface of the pins extend in a direction close to the tangential direction of the outer surface of the side wall 11. In this case, the length of the small hole formed by the pins on both sides in the circumferential direction becomes longer, that is, the thickness of the side wall 11 becomes thicker, and the standing direction of the pins on both sides in the circumferential direction is the side wall. In some cases, a portion in which a small hole is not formed in the side wall 11 occurs. If the small hole becomes longer in the center line direction or a portion in which the small hole is not formed in the side wall 11 as described above, the flow resistance when the oil flows in the inner and outer directions of the filter 3 increases, and the oil is efficiently filtered. Can not do.

  Moreover, it is preferable that the area | region which shape | molds the side wall 11 outer surface with each predetermined area | region shaping | molding die shall be the range of 1 / 4-1 / 6 continuing in the circumferential direction of this outer side surface of this side wall 11. For example, when forming a 1/5 region continuous in the circumferential direction of the outer surface of the side wall 11 with each predetermined region forming die, the first outer mold 33 may be configured with five predetermined region forming dies, When a 1/6 region continuous in the circumferential direction of the outer surface of the side wall 11 is formed, the first outer mold 33 may be configured by six predetermined region forming dies. Thus, by setting the region of the outer surface of the side wall 11 formed by each predetermined region mold to be in the range of 1/4 to 1/6 of the outer surface, the number of predetermined region molds is six or less. The structure of the 1 outer mold 33 is not complicated, and the cost increase of the mold 1 can be suppressed.

  The present invention can also be applied to the case where the cross-sectional shape of the filter 3 is, for example, an ellipse, or a pentagon and a hexagon. In this case, the first outer mold 33 may be divided into five and six predetermined area molds.

  In this embodiment, the case where the filter 3 is formed with its center line oriented in a substantially horizontal direction has been described. However, the present invention forms the filter 3 with its center line oriented in a substantially vertical direction. The present invention can also be applied to the case where the center line is oriented in a direction inclined with respect to the horizontal plane.

  Furthermore, the filter 3 molded by the molding die 1 of the present invention can be used for an automatic transmission of an automobile, a power machine other than an automobile, and the like.

  As described above, the filter molding die according to the present invention can be used to mold a cylindrical filter used in, for example, an automobile engine with a resin material.

It is a longitudinal cross-sectional view of the shaping | molding die of the filter which concerns on embodiment of this invention. It is a perspective view of the filter shape | molded with the shaping | molding die. It is a perspective view which shows the state which incorporated the filter in the pipe member. It is a top view which expands and shows the side wall of a filter. It is the sectional view on the AA line in FIG. It is a longitudinal cross-sectional view which expands and shows the 1st pin vicinity of a 1st predetermined area | region shaping | molding die. It is a perspective view of the filter whose cross-sectional shape is a substantially square.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 3 Filter 11 Side wall 13 Bottom wall 21 Small hole 31 Inner mold 31a Side wall molded surface 31b Bottom wall molded surface 33 First outer mold 35 Second outer mold 35a Bottom wall molded surface 37-40 First to fourth predetermined regions Mold 37a. 38a, 39a, 40a 1st-4th side wall molding surface 45-48 1st-4th pin 49 Bottom wall side pin S Cavity

Claims (1)

A filter molding die used when molding a bottomed cylindrical filter formed with a large number of small holes for fluid filtration on each of a side wall and a bottom wall with a resin material,
An inner mold having a side wall molding surface and a bottom wall molding surface for molding the side wall inner surface and the bottom wall inner surface of the filter, respectively;
A first outer mold having a sidewall molding surface for molding the sidewall outer surface of the filter;
A second outer mold having a bottom wall molding surface for molding the bottom wall outer surface of the filter,
The first outer mold is divided into a plurality of predetermined area molding dies that respectively mold predetermined areas of approximately ¼ or less continuous in the circumferential direction of the sidewall outer surface,
The predetermined area forming molds move toward and away from the inner mold in the thickness direction of the side wall, and the second outer mold and inner mold move relatively in the thickness direction of the bottom wall and move toward and away from each other. By doing so, the inner mold, the first outer mold and the second outer mold can be switched between a mold closed state in which a cavity is formed and a mold open state in which a filter molded in the cavity can be removed,
A pin that protrudes in the moving direction of the predetermined area molding die on the side wall molding surface of each predetermined area molding die and that forms a small hole in the side wall by contacting the side wall molding surface of the inner mold with the tip closed. Many are established,
One bottom wall molding surface of the bottom wall molding surface of the second outer mold and the bottom wall molding surface of the inner mold projects in the relative movement direction of the second outer mold and the inner mold, and the tip is closed. A filter molding die characterized in that a large number of pins that stand against the other bottom wall molding surface to form small holes in the bottom wall are provided upright.

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