JP4909228B2 - Extrusion mold - Google Patents

Description

  The present invention relates to an extrusion mold for forming a molded body having a hollow hole by extruding a molding material such as a cement-based molding material.

  A molded body B (see FIG. 10) having a plurality of hollow holes 23 formed by extrusion molding a molding material such as a cement-based molding material is used as an outer wall of a building.

  Such a molded body B was manufactured using, for example, an extrusion mold as shown in FIG. The illustrated extrusion mold is provided with a core mold 32 for forming the hollow hole 23 in the vicinity of the extrusion port 36 of the flow path 33 through which the molding material of the main body mold 31 flows. The core mold 32 is provided with a plurality of protrusions 35 arranged in a line with respect to a plurality of support sections 34 that are long in a direction orthogonal to the drawing sheet surface. A plurality of hollow holes 23 are provided according to the number of hollow holes 23 provided in the body B.

  In such an extrusion mold, the molding material completely branches up and down at the rear end portion of the support portion 34 and flows between the support portions 34, and is further introduced between the rows of the plurality of rows of protrusions 35. Is done. After that, while the molding material flows between the rows of the projections 35, the molding material flows up and down until the molding material is extruded from the extrusion port 36 of the main body mold 31, and is filled between the projections 35 in each row. Is done. The flow path 33 is formed so that the flow path 33 is wide at the position of the support section 34 and gradually becomes narrower as it goes to the extrusion port 36 in order to provide the support section 34 with a space above and below the paper surface. Yes.

A core mold 32 as shown in FIG. 11B has also been proposed (see Patent Documents 1 and 2). The core mold 32 has a plurality of slits 37 formed on the front end side, a plurality of projections 35 for forming the hollow hole 23 between the slits 37, and the slit 37 on the rear end side. A plurality of introduction holes 38 communicating with the crossing positions are provided. Then, after the molding material is introduced into each introduction hole 38, the molding material is supplied into the slit 37 from the intersection of the slits 37. For this reason, the molding material is supplied between the protrusions 35 from a plurality of locations around each protrusion 2 and is uniformly filled around the protrusions 35.
JP 2005-254345 A JP 2006-51682 A

  When the molded body material is extruded by the extrusion mold as exemplified above, the molded body B having the hollow holes 23 is continuously formed, and the air flows into the hollow holes 23 of the obtained molded body B. By doing so, the internal pressure of the hollow hole 23 becomes equivalent to the outside of the molded body B.

  However, when a part of the hollow hole 23 is buried due to some trouble in the extrusion molding process of the molding material, air is not supplied into the hollow hole 23 formed thereafter, and the pressure inside the hollow hole 23 is not supplied. May become very low. In such a case, the formed molded body B is in a state where breakage is likely to occur due to a pressure difference between the inside and the outside of the hollow hole 23, and the hollow hole 23 is sequentially crushed during the forming, and the hollow hole 23 is not formed. The molded body B may be damaged when a load is applied when the molded body B is cut.

  The present invention has been made in view of the above points. In forming a molded body having a hollow hole by extruding a molding material such as a cement-based molding material, a part of the hollow hole is formed in the extrusion process. Extrusion that can suppress the decrease in the internal pressure of the hollow hole and suppress the occurrence of breakage in the molded body and perform stable production even when a situation such as being buried due to some trouble occurs. An object is to provide a mold.

  An extrusion mold A according to the present invention is an extrusion mold A for forming a molded body B having a plurality of hollow holes 23 by extruding a molding material, and the flow direction of the molding material is in its flow direction. And a plurality of protrusions 2 projecting from the support part 1 toward the forward direction side of the flow direction. A vent hole 17 penetrating the protrusion 2 in the flow direction is provided, and a flow hole 3 penetrating the support portion 1 in the flow direction and an air flow supplied from the outside flow through the support portion 1. Ventilation passages 20 and 21 communicating with the vent hole 17 of the protrusion 2 are provided.

  The air passages 20 and 21 include a main air passage 20 through which an air flow supplied from the outside flows, and a branch air passage 21 that branches from the main air passage 20 and communicates with the air holes 17. The main ventilation path 20 is provided along the longitudinal direction outside the outer edges on both sides along the longitudinal direction of the area where the protrusions 2 of the support portion 1 are projected, and the branch ventilation path 21 is formed in the area. It is preferable that a plurality of parallel vents are provided on the inner side along the short direction of the region, and the end portions on both sides of the branch air passage 21 are respectively communicated with the main air passages 20.

  Further, the support portion 1 is configured by superimposing a front body 1a disposed on the forward direction side in the flow direction of the molding material and a rear body 1b disposed on the reverse direction side in the flow direction. The ventilation paths 20 and 21 are preferably formed in a space sandwiched between the front body 1a and the rear body 1b.

  According to the present invention, when the molding material is extruded to obtain the molding B, the molding material has the hollow hole 23 by passing through the flow hole 3 of the support portion 1 and the projection 2. B can be molded. Further, it is possible to prevent the internal pressure of the hollow hole 23 from being reduced by flowing the air flow into the hollow hole 23 through the ventilation paths 20 and 21 and the ventilation hole 17 during the molding, and the internal pressure is an external pressure. Breakage of the molded product B due to being smaller than that can be suppressed.

  Further, by forming the air passages 20 and 21 by the main air passage 20 and the branch air passage 21, the length of the branch air passage 21 is shortened, and the protrusion connected to each branch air passage 21. Reducing the number of the vent holes 17 in the section 2 and supplying the air flow from both ends of the branch air passage 21 to reduce the flow resistance when the air flow flows through the extrusion mold A. Even if the air flow is supplied to the extrusion mold A at a low pressure near atmospheric pressure, the air flow can be discharged from each vent hole 17 and the internal pressure of the hollow hole 23 is prevented from being excessive, and the extrusion molding is performed. The pressure difference between the airflows flowing out from the air holes 17 caused by the difference in path length until the airflow supplied to the mold A flows out of the air holes 17 can be reduced, and the internal pressure of the hollow hole 23 can be reduced. Becomes larger than the external pressure or the difference in the internal pressure of the hollow hole 23 is large. In which it is possible to suppress the damage of the molded body B caused by or become.

  Further, by forming the air passages 20 and 21 in a space sandwiched between the front body 1a and the rear body 1b, the air passages 20 and 21 can be easily formed inside the support portion 1. Is.

  The best mode for carrying out the present invention will be described below with reference to FIGS.

  As shown in FIGS. 3, 4, and 7 to 9, the illustrated extrusion mold A includes a base portion 8, a base portion 9, a support portion 1, and a protrusion 2 (hollow pin).

  The base portion 8 is formed in a cylindrical shape having both sides opened, and the molded body B after extrusion molding is exposed to the outside from the opening on the tip side (the forward direction side in the flow direction of the molding material, hereinafter referred to as the forward direction side). Extruded. Moreover, the collar part 10 is extended toward the outer peripheral direction from the outer periphery of the edge part of the base end side (the reverse direction side of the distribution direction of a molding material. Hereafter, it is called a reverse direction side). The hollow part 11 inside the base part 8 constitutes a flow passage for the molding material, and the molding material flows from the reverse side of the base part 8 to the forward side in the hollow part 11. In the illustrated example, in order to mold the plate-shaped molded body B, the cross-sectional shape of the hollow portion 11 is formed in a rectangular cross section in which a pair of opposing sides is longer than the other pair of opposing sides. .

  The base portion 9 is formed of a plate-like body in which one surface side is disposed on the forward direction side and the other surface side is disposed on the reverse direction side. The base portion 9 is provided with a hollow portion 12 that penetrates from the reverse direction side to the forward direction side at a position that matches the hollow portion 11 of the base portion 8. The hollow portion 12 also constitutes a flow path of the molding material, and the molding material flows in the hollow portion 12 from the reverse direction side to the forward direction side of the base portion 9.

  The support part 1 is provided so as to be interposed between the flange part 10 and the base part 9 of the base part 8, and is constituted by a hollow part 11 of the base part 8 and a hollow part 12 of the base part 9. The flow path of the molding material is provided so as to be divided into a forward direction side and a reverse direction side in the flow direction. The support portion 1 is formed of a plate-like body, and its forward-side surface overlaps the reverse-side surface of the flange portion 10, and the reverse-side surface is a forward-side surface of the base portion 9. It is supposed to overlap. A plurality of protrusions 2 are provided on the surface of the support portion 1 in the forward direction along the flow direction of the molding material. This protrusion 2 is accommodated in the hollow part 11 of the base part 8 so as to protrude from the support part 1 toward the forward direction in the flow direction of the molding material. Further, the support portion 1 is provided with a plurality of flow holes 3 penetrating the support portion 1 in the flow direction of the molding material, and between the hollow portion 12 of the base portion 9 and the hollow portion 11 of the base portion 8. A molding material flows through the flow hole 3.

  In addition, a plurality of communication holes 13 are formed at positions corresponding to each other in the flange portion 10, the support portion 1, and the base portion 9 of the base portion 8, and the communication holes 13 are connected to the base portion 8, In order to attach the support part 1 and the base part 9 to the extrusion molding machine as a reference for alignment when the extrusion mold A is configured, or to insert an appropriate fixing tool such as a bolt into the communication hole 13. Or can be used.

  The structure of the support part 1 and the protrusion 2 in this embodiment is demonstrated in detail.

  Plural protrusions 2 are provided in parallel and in parallel. The protrusion 2 shown in the figure has a cylindrical shape, but the protrusion 2 is formed in another appropriate shape such as a hexagonal column depending on the shape of the hollow hole 23 formed in the molded body B. The plurality of protrusions 2 are provided so as to be spaced apart from each other and arranged in a planar hexagonal lattice shape. That is, as shown in FIG. 5 and the like, the interval between the adjacent protrusions 2 is formed to be constant, and the six protrusions 2 surround the periphery of one protrusion 2 in the shape of a regular hexagon. The distance between the protrusions 2 and the surrounding protrusions 2 and the distance between the surrounding protrusions 2 are all made equal. In FIG. 5, some of the protrusions 2 are indicated by broken lines. Each protrusion 2 is formed in a columnar shape, and a large-diameter portion 14 having a diameter larger than that of the base portion is formed at the end portion on the forward direction side, and as shown in FIGS. Further, between the portion on the opposite direction side of each protrusion 2 and the large diameter portion 14, an enlarged diameter portion 15 having a gradually increasing diameter is formed. Moreover, the end surfaces of all the protrusions 2 are formed flush with each other. Further, a connecting portion 16 having a smaller diameter than the base end portion is formed at the base end portion on the opposite side of the protrusion 2 (see FIG. 9). Further, as shown in FIGS. 7 to 9 and the like, the protrusion 2 is provided with a vent hole 17 penetrating the inside thereof in the flow direction of the molding material from the reverse direction side to the forward direction side.

  Here, the interval between the adjacent protrusions 2 (interval between the large diameter portions 14) is set as appropriate. If this interval is reduced, the interval between the hollow holes 23 formed in the molded body B is reduced, thereby reducing the weight. Although it is possible to make a contribution, it is preferable to leave an interval that can give sufficient strength to the molded body B. For example, when a cement-based molding material is used as the molding material, this interval should be 1.5 mm or more. Is preferred. Moreover, it is preferable that the internal diameter of the vent hole 17 is 1 mm or more.

  On the other hand, the support part 1 is formed of a plate-like body in which one surface side is disposed on the forward direction side and the other surface side is disposed on the reverse direction side. The support portion 1 is configured by overlapping a plate-shaped front body 1a (see FIGS. 1 and 2) disposed on the forward direction side and a plate-shaped rear body 1b disposed on the reverse direction side. ing.

  The front body 1a is provided with a plurality of connection holes 18 penetrating through the surface on the forward direction side and the surface on the reverse direction side at a position coinciding with the protruding position of the protrusion 2. In other words, the openings of the plurality of connection holes 18 are arranged inside a rectangular region that is arranged in a planar hexagonal lattice pattern on both surfaces of the front body 1 a and matches the arrangement of the protrusions 2. The inner diameter of the connection hole 18 matches the inner diameter of the connection portion 16 of the protrusion 2, and the protrusion 2 is protruded from the support portion 1 by fitting the connection portion 16 of the protrusion 2 into the connection hole 18. (See FIG. 9 etc.). Here, the length dimension of the connection portion 16 is formed to be smaller than the length dimension of the connection hole 18, and therefore, the reverse side portion of the connection hole 18 is a hollow opening on the reverse side surface. A connecting space 19 is formed.

  In addition, the support portion 1 is provided with a main air passage 20 and a branch air passage 21 as the air passages 20 and 21 that serve as air flow paths.

  The main ventilation path 20 is reverse to the outside of the rectangular area (the area where the protrusion 2 protrudes) where the opening of the connection hole 18 is provided on the reverse side surface of the front body 1a. It is recessed in the shape of a groove so as to open in the direction side surface. The main air passage 20 is provided along the long side outside the two long sides facing each other in the rectangular region.

  A plurality of branch vents 21 are provided in parallel in parallel between the two main vents 20 so as to communicate with the main vents 20 at both ends and to open on the opposite side surface. Yes. The branch air passage 21 is formed inside a rectangular region where the opening of the connection hole 18 is provided, and each branch air passage 21 sequentially connects the connection spaces 19 of the plurality of connection holes 18 in the region. It is provided to cross. As a result, the connection spaces 19 of all the connection holes 18 communicate with any one of the branch ventilation paths 21.

  Openings on the opposite side of the main air passage 20, the branch air passage 21, and the connection space 19 are closed by the rear body 1b. Therefore, the main air passage 20, the branch air passage 21, and the connection space 19 are supported by the support portion. 1 is provided. In this way, the support portion 1 is formed by the front body 1a and the rear body 1b, and the main ventilation path 20, the branch ventilation path 21 and the connection space 19 are formed in a space sandwiched between the front body 1a and the rear body 1b. By forming, the main ventilation path 20, the branch ventilation path 21, and the connection space 19 which have a complicated form in the inside of the support part 1 can be formed easily. Here, in the illustrated form, the front body 1a is recessed to form the main air passage 20, the branch air passage 21, and the connection space 19 so as to open on the opposite side surface, and the main air passage 20, The openings of the branch air passage 21 and the connection space 19 are closed by the rear body 1b. However, the present invention is not limited to this configuration. For example, the main air passage 20, the branch air passage 21, and the connection space are formed in the rear body 1b. At least one of 19 may be recessed and closed by the front body 1a.

  The main ventilation path 20 may be formed outside the area where the opening of the connection hole 18 (connection space 19) is provided (the area where the protrusion 2 is projected). The position where 21 is formed may be a position that crosses all the connection spaces 19 inside the region, but the main air passage 20 is arranged outside the outer edges on both sides along the longitudinal direction of the region as described above. If a plurality of branch air passages 21 are formed in parallel with each other along the short direction of the region so as to connect the main air passage 20, the plurality of branch air passages 21 are formed in parallel with each other. The path length of the ventilation path 21 can be formed as short as possible.

  In addition, an air supply path 22 that communicates with the main ventilation path 20 and that opens at the outer peripheral surface of the front body 1a and communicates with the outside of the support section 1 is provided inside the front body 1a. Two air supply passages 22 are provided for each main air passage 20, and a total of four air supply passages 22 are provided.

  In addition, the plurality of flow holes 3 provided in the support portion 1 have their end portions on the opposite direction side opened on the surface on the opposite direction side of the support portion 1 and communicated with the hollow portion 12 of the base portion 9. The end on the direction side is opened at the surface on the forward direction side of the support portion 1, communicates with the hollow portion 11 of the base portion 8, and penetrates the support portion 1 in the flow direction of the molding material.

  The plurality of flow holes 3 are provided at positions that surround the plurality of protrusions 2 protruding from the support portion 1, and are provided so as to uniformly surround the protrusion 2. That is, the plurality of flow holes 3 provided around each protrusion 2 are formed such that the intervals between the protrusions 2 and the flow holes 3 are all equal and the intervals between the flow holes 3 are all equal. Is done. In the illustrated example, each flow hole 3 is formed at a central position surrounded by three protrusions 2, and each protrusion 2 is a center surrounded by six flow holes 3 arranged in a regular hexagon. It is formed in a position, and thereby, the distance between each protrusion 2 and each surrounding circulation hole 3 is constant, and the distance between each surrounding circulation hole 3 is constant. .

  Each of the plurality of flow holes 3 is provided with an outflow side taper portion 4 whose inner diameter increases toward the forward direction side on the inner peripheral surface of the end portion on the forward direction side. The outflow side taper portion 4 is provided on the front body 1 a of the support portion 1. An inflow side taper portion 5 whose inner diameter increases toward the opposite direction side is provided on the inner peripheral surface of the end portion on the opposite direction side of each flow hole 3. The inflow side taper portion 5 is provided on the rear body 1 b of the support portion 1.

  At this time, on the surface on the forward direction side of the support portion 1, the outflow side taper portions 4 of the adjacent flow holes 3 are formed adjacent to each other, and a plurality (six in the drawing) of the outflow side taper portions 4 are formed. The flat area | region 24 in which the connection hole 18 is formed is ensured in the position enclosed by (refer FIG. 5).

  As shown in FIGS. 4, 6, 8, etc., the inflow side taper portions 5 of the adjacent circulation holes 3 are formed adjacent to each other on the opposite side surface of the support portion 1. A ridge portion 6 is formed at the boundary between the outflow side taper portions 4. Since both sides of the ridge portion 6 are formed with the outflow side taper portion 4, each ridge portion 6 is inclined downward toward the forward direction side. The ridge portion 6 is formed in a straight line when viewed from the reverse direction side, and the ridge line of the ridge portion 6 is formed so as to be recessed toward the forward direction side. At this time, the flow hole 3 is formed at a position surrounded by a plurality of (three in the drawing) ridges 6. Moreover, the top part 7 which protrudes toward a reverse direction side is formed in the position (position which agree | coincides with the formation position of the connection hole 18) where the edge parts of several (six in the illustration) ridge parts 6 cross. . In the example shown in the drawing, a flat area having a small area is formed at the tip of the top portion 7. More preferably, the tip of the top portion 7 is formed in a pointed shape.

  In addition, in FIG. 1, illustration of the inflow side taper part 5, the ridge part 6, and the top part 7 in the rear part 1b is abbreviate | omitted.

  Next, the shaping | molding of the molded object B using the extrusion mold A formed in this way is demonstrated.

  The above-described extrusion mold A is attached to an appropriate extrusion molding apparatus, an extrusion pressure is applied to the molding material, and the molding material is supplied from the base portion 9 side to the molding material flow passage in the extrusion molding die A. The molded body B is molded by extruding from the forward direction side opening.

  Although it will not restrict | limit especially if it is a material used for extrusion molding as a molding material, Especially a cement-type molding material can be used. The cement-based molding material 2 can have an appropriate composition, and is prepared, for example, by blending aggregate, fiber, colorant and the like with cement as necessary, and kneading with water. As the cement, arbitrary materials such as ordinary Portland cement, slag cement, alumina cement, and early strength cement can be used. In addition, as the aggregate, silica, silica powder, silica sand, fly ash, slag, crushed stone, and the like can be used. As the fiber, polypropylene fiber, vinylon fiber, acrylic fiber, pulp, carbon fiber, cotton, hemp, metal fiber and the like can be used. Further, iron black, carbon black, chromium oxide, or the like can be used as a colorant.

  In particular, as a cement-based molding material, it contains an oily substance and further contains an emulsifier (inverse emulsifier) such as a nonionic surfactant, various anionic surfactants, and a cationic surfactant as necessary. It is also preferable to use what forms an inverse emulsion (W / O emulsion). Since such an inverse emulsion type cement-based molding material has a certain shape-retaining property, the shape can be maintained when the molded body B having the hollow holes 23 is molded. As will be described later, extrusion can be performed without applying excessive pressing force, and the destruction of the inverse emulsion structure at the time of molding can be suppressed, thereby preventing the subsequent curing and curing from being hindered. it can.

  The oily substance is not particularly limited as long as it can form an inverse emulsion with water, and usually a hydrophobic liquid substance is used. For example, toluene, xylene, kerosene, styrene, divinylbenzene, methyl methacrylate, Examples include trimethylolpropane trimethacrylate and unsaturated polyester resins. Among these, when using those having a polymerizable double bond (vinyl monomer) such as styrene, divinylbenzene, methyl methacrylate, trimethylolpropane trimethacrylate, unsaturated polyester resin, etc. In order to accelerate the polymerization of the oily substance, a polymerization initiator such as an organic peroxide or a persulfate, or a crosslinking agent such as trimethylolpropane trimethacrylate can be used in combination.

  In this extrusion molding, when the molding material passes through the support portion 1 and the protrusion 2, the molding material first flows into each flow hole 3 of the support portion 1 and branches, and after passing through this flow hole 3, The molding material passes between the plurality of protrusions 2 and flows in parallel along the protruding direction of the protrusions 2 around the protrusions 2 between the adjacent protrusions 2. At this time, the molding material flows out from the flow holes 3 formed so as to be evenly arranged at positions surrounding the periphery of the protrusion 2, thereby causing an even flow of the molding material around the protrusion 2. For this reason, the molding material can be sufficiently filled around the protrusion 2 without applying a high extrusion pressure. In addition, while the molding material flows between the protrusions 2 in this way, the molding material flowing around the protrusions 2 becomes familiar and integrated.

  In such a flow of the molding material, when the molding material flows into the flow hole 3 from the hollow portion 12 of the base portion 9, the ridge portion 6 formed on the opposite side surface of the support portion 1 and The molding material is easily branched by the top portion 7 and is easily guided to the flow hole 3. In particular, when the tip of the top portion 7 is formed in a pointed shape, deposition of the molding material on the top portion 7 is suppressed, and the inflow of the molding material into the flow hole 3 is further promoted. Furthermore, the inflow side taper portion 5 is provided at the opposite end portion of the flow hole 3 to facilitate the flow of the molding material into the flow hole 3.

  For this reason, the extrusion pressure required for the molding material to pass through the flow holes 3 can be reduced, and the pressure applied to the molding material can be suppressed.

  Further, when the molding material flows out from each flow hole 3 to the hollow portion 11 side of the base portion 8, the flow-out hole 3 is provided with the outflow side taper portion 4, so that the molding material spreads in the lateral direction. It will be leaked. For this reason, the fluidity | liquidity at the time of a molding material flowing out from the flow hole 3 improves, and deposition of a molding material can be suppressed. Further, the filling property around the protrusions 2 when the molding material passes between the protrusions 2 can be further improved, and the familiarity between the molding materials around the protrusions 2 can be further improved. .

  Then, when this molding material is pushed out from the opening on the forward direction side of the base portion 8, a molded body B having a hollow hole 23 as shown in FIG. 10 is formed. FIG. 10A shows a molded body B obtained when the columnar protrusion 2 is applied as in this embodiment, and has a hollow hole 23 having a circular cross section. Further, when a hexagonal columnar shape is applied as the protrusion 2, a molded body B having a hollow hole 23 having a hexagonal cross section as shown in FIG. 10B can be obtained, and other appropriate shapes can be obtained. By adopting the protrusion 2, a molded body B having a hollow hole 23 having a desired shape can be obtained.

  The obtained molded body B is cut so as to have a desired dimension as required, and is cured and cured as necessary, particularly when formed of a cement-based molding material.

  Further, in the extrusion molding process as described above, an air flow such as air is supplied from an opening outside the support portion 2 of each air supply path 22. In this case, the supplied airflow flows from the air supply paths 22 into the main ventilation paths 20 and further branches into the plurality of branch ventilation paths 21 and flows in. At this time, airflow flows into the plurality of branch air passages 21 from the end portions on both sides thereof. Then, the airflow flows from the branch ventilation paths 21 into the vent holes 17 in the projections 2 through the connection spaces 19, and flows out from the openings on the front end surfaces of the projections 2. For this reason, airflow such as air is supplied to the hollow holes 23 formed in the molded body B.

  When airflow is supplied to the hollow hole 23 of the molded body B in this way, it is possible to prevent the pressure in the hollow hole 23 from being lowered and to prevent the hollow hole 23 from being buried.

  In addition, when a part of the hollow hole 23 is buried due to some trouble during the extrusion molding process of the molding material, air is not supplied into the hollow hole 23 formed thereafter, and the pressure inside the hollow hole 23 is reduced. It can be very low. In such a case, the formed molded body B is likely to be damaged due to a pressure difference between the inside of the hollow portion and the outside. For this reason, there is a possibility that the hollow holes 23 are sequentially crushed during molding, and the hollow holes 23 may not be formed. Further, even when the hollow holes 23 are formed, a load is applied to cut the molded body B. The molded body B may be damaged. However, when the airflow is supplied to the hollow hole 23 of the molded body B as described above, it is possible to prevent the pressure inside the hollow hole 23 from being lowered even if a part of the hollow hole 23 is buried. , Damage to the molded body B as described above can be prevented.

  Here, if the pressure of the air flow supplied into the hollow hole 23 is too high, the molded body B may be damaged due to the difference between the pressure inside the hollow hole 23 and the pressure outside the molded body B. The pressure of the airflow is preferably a pressure near atmospheric pressure. At this time, when the flow resistance of the airflow flowing out from the air supply passage 22 through the main air passage 20, the branch air passage 21, the connection space 19, and the air vent 17 is large, the air flow is reduced at a low pressure close to the atmospheric pressure. It becomes difficult to supply.

  However, in the present embodiment, as described above, the branch air passage 21 is formed so that the path length is as short as possible, and the air flow is supplied from both ends of the branch air passage 21. The path length of the air flow at 21 remains at a half of the length of the branch ventilation path 21 at the maximum. For this reason, the whole path | route length of airflow becomes short, and flow-path resistance is reduced. Moreover, since the number of the vent holes 17 of the protrusion 2 connected to each branch vent path 21 can be reduced, the flow path resistance is further reduced. In addition, since airflow is supplied from both sides of the branch ventilation path 21 in this way, even if clogging occurs in the middle of the branch ventilation path 21, the airflow can be stably supplied to each ventilation hole 17.

  In addition, when the difference in flow resistance between the airflows flowing out from the hollow holes 23 of the protrusions 2 until the airflow flows out from the hollow holes 23 increases, the difference in pressure between the airflows increases, and the compact B There is a possibility that the pressure difference in each hollow hole 23 formed in the above becomes large, causing the molded body B to be damaged.

  However, the difference in the channel resistance is mainly caused by the difference in the path length from the time when the airflow flows into the branch ventilation path 21 to the time when the airflow flows into the vent hole 17 of each projection 2. By making the path length of the airflow in the branch air passage 21 shorter, the difference in the path length of the airflow can be made smaller, so that the airflow flowing out from the hollow hole 23 of each protrusion 2 can be reduced. The pressure difference can be reduced.

  Further, if the flow passage resistance in the branch air passage 21 is reduced by increasing the cross-sectional area of the branch air passage 21 as much as possible, it can contribute to the reduction of the overall flow passage resistance, and the air flow is supplied at a lower pressure. Will be able to. Moreover, since the difference in flow path resistance due to the difference in path length in the branch air passage 21 can be reduced, the difference in flow path resistance between the airflows flowing out from the hollow holes 23 of the respective protrusions 2 is also reduced. The pressure difference between the airflows can be further reduced. In this case, the cross-sectional area of the branch air passage 21 can be set as appropriate. Preferably, for each branch air passage 21, the cross-sectional area of the branch air passage 21 is S, and the air flow in the branch air passage 21 is If the number of the inflow positions of n is n and the sum of the cross-sectional areas of the vent holes 17 of all the protrusions 2 connected to the branched vent path 21 is s, the relation of S ≧ s / n is established. It is preferable. Here, in this embodiment, since airflow flows from both ends of the branch air passage 21, n = 2 and it is preferable that S ≧ s / 2. Here, in the case where the protrusions 2 are formed densely in order to form the hollow portions 23 densely in the molded body B, the air holes 17 are also formed densely, and the branch air passage 21 is formed by the air holes. Since it is necessary to sew between 17, it is difficult to form the branch air passage 21 with a sufficiently large width. For this reason, in order to form the branch air passage 21 so as to have a sufficiently large cross-sectional area, it is necessary to secure a sufficient depth of the branch air passage 21. For this purpose, it is preferable to form the front body 1a so as to be sufficiently thick.

It is a disassembled perspective view which shows the structure of the support part and protrusion in an example of embodiment of this invention. FIG. 2 is a partially enlarged view of FIG. 1. It is a perspective view which shows an example of embodiment same as the above. It is another perspective view same as the above. It is a partial front view same as the above. It is a partial rear view of the same as the above. It is a partially broken perspective view same as the above. It is another perspective view fractured | ruptured partially same as the above. It is a fragmentary sectional view same as the above. (A) And (b) is the partially broken perspective view which shows the example of a molded object. (A) is sectional drawing which shows an example of a prior art, (b) is the partially broken perspective view which shows the other example of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS A Extrusion mold B Molding body 1 Support part 1a Front part 1b Rear part 2 Protrusion part 3 Flowing hole 17 Vent hole 20 Ventilation path (main ventilation path)
21 Airway (branch airway)

Claims (3)

An extrusion mold for molding a molded body having a plurality of hollow holes by extruding a molding material,
A support part that partitions the flow path of the molding material into a forward direction side and a reverse direction side of the flow direction; and a plurality of protrusions that protrude from the support part toward the forward direction side of the flow direction;
The protrusion is provided with a vent hole penetrating the protrusion in the flow direction,
The support portion is provided with a flow hole penetrating the support portion in the flow direction, and a ventilation path through which an air flow supplied from the outside flows and communicates with the vent hole of the protrusion. Extrusion mold. The air passage is composed of a main air passage through which an air flow supplied from the outside flows, and a branch air passage branched from the main air passage and communicating with the vent hole,
The main ventilation path is provided along the longitudinal direction on the outer side of the outer edges on both sides along the longitudinal direction of the region where the protrusions in the support portion are projected.
A plurality of the branch air passages are provided in parallel inside the region along the short direction of the region, and both ends of the branch air passage are communicated with the main air passages, respectively. The extrusion mold according to claim 1, wherein The support portion is configured by superimposing a front body disposed on the forward direction side in the flow direction of the molding material and a rear body disposed on the reverse direction side of the flow direction,
The extrusion mold according to claim 1 or 2, wherein the ventilation path is formed in a space sandwiched between the front body and the rear body.

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