JP2019206135A - Core mold of injection mold and injection molding method - Google Patents

Core mold of injection mold and injection molding method Download PDF

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JP2019206135A
JP2019206135A JP2018103409A JP2018103409A JP2019206135A JP 2019206135 A JP2019206135 A JP 2019206135A JP 2018103409 A JP2018103409 A JP 2018103409A JP 2018103409 A JP2018103409 A JP 2018103409A JP 2019206135 A JP2019206135 A JP 2019206135A
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JP6788199B2 (en
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雄一 近藤
Yuichi Kondo
雄一 近藤
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Abstract

To extract a cylindrical molded product from a core mold constituting a mold without damaging it after injection molding with a thermoplastic resin the cylindrical molded product in which only one end in an extraction direction is opened.SOLUTION: When a molded product Pis extracted, the molded product Pis slightly inflated with respect to a core mold Ato form an extraction gap Sso as to extract the molded product Pby pushing out an ejector pin Ein an extraction direction so that compressed air supplied to a flow gap Sof the core mold Apasses through a communication gap Sformed between a tip of the ejector pin Eand a tip of the core mold Ato supply the compressed air between an outer peripheral surface of the core mold Aand an inner peripheral surface of the molded product P.SELECTED DRAWING: Figure 5

Description

本発明は、抜取り方向の一端部のみが開放された筒状又は袋状の射出成形品の抜取りを容易にした射出成形型の中子型、及び射出成形方法に関するものである。   The present invention relates to an injection mold core and an injection molding method that facilitates the extraction of a cylindrical or bag-like injection molded product in which only one end portion in the extraction direction is opened.

ロッド状の中子型と、当該中子型の周囲を取り囲んで配置された複数の外型との間に形成されるキャビティに、溶融状の熱可塑性エラストマーを射出して、抜取り方向の一端部のみが開放された筒状又は袋状の成形品を成形することができる。しかし、成形品が一端部のみが開放された筒状又は袋状であるために、成形後において、中子型から成形品を抜き取ることが容易ではなく、無理に抜き取ると、成形品を損傷させてしまう。   One end portion in the extraction direction by injecting a molten thermoplastic elastomer into a cavity formed between the rod-shaped core mold and a plurality of outer molds surrounding the core mold A cylindrical or bag-shaped molded product with only the opening can be formed. However, since the molded product is cylindrical or bag-shaped with only one end opened, it is not easy to extract the molded product from the core mold after molding, and forcibly removing it will damage the molded product. End up.

特に、筒状又は袋状の成形品の一部に、抜取り方向に沿ってアンダーカット部が存在していたり、開放端から閉塞端に向けて横断面の寸法が漸次小さくなる逆テーパーの成形品であると、その抜取りが一層に困難となる。また、横断面の形状が全長に亘って同一の成形品であっても、その長さが長い場合には、中子型との総接触面積が大きくなることで、成形品の抜取りのための抵抗が大きくなって、成形品を損傷することなく抜き取ることは、容易ではない。   In particular, a part of a cylindrical or bag-shaped molded product has an undercut portion along the extraction direction, or a reverse-tapered molded product in which the cross-sectional dimension gradually decreases from the open end to the closed end. If it is, the extraction will become more difficult. Moreover, even if the shape of the cross section is the same over the entire length, if the length is long, the total contact area with the core mold is increased, so that the molded product can be removed. It is not easy to extract the molded product without damaging it because of increased resistance.

特許文献１には、加飾シートで覆われた樹脂の加飾成形品を成形する方法が開示されている。この加飾シートの成形方法は、離間（型開き）した一対の成形型の間に加飾シートを平面状にして配置した状態で、一方の成形型に形成された通気孔に負圧を作用させることで、当該加飾シートを当該一方の成形型の成形面に密着させ、この状態で一対の成形型を閉じて形成されるキャビティに溶融樹脂を供給することで、成形品の一方の表面に加飾シートを一体に形成させて、加飾成形品を成形している。この成形方法では、空気圧（負圧）は、一対の成形型の一方の成形面に加飾シートを密着させるのに使用されており、成形品の抜取りのためではない。   Patent Document 1 discloses a method of molding a resin decorative molded product covered with a decorative sheet. In this decorative sheet molding method, a negative pressure is applied to the vent hole formed in one mold while the decorative sheet is arranged in a plane between a pair of spaced apart molds. By bringing the decorative sheet into close contact with the molding surface of the one mold, and supplying the molten resin to the cavity formed by closing the pair of molds in this state, one surface of the molded product The decorative sheet is formed integrally to form a decorative molded product. In this molding method, air pressure (negative pressure) is used to bring the decorative sheet into close contact with one molding surface of the pair of molding dies, not for extracting the molded product.

また、特許文献２には、射出成形ではないが、内外の各周面に貫通する無数の貫通孔が形成された芯金の表面に生ゴム等の弾性を有する素材を巻き付けた状態で、加硫により筒状の弾性管を成形し、その後に、芯金の内部に加圧流体を供給することで、無数の貫通孔を通して、当該芯金と筒状の弾性管との間に僅かの隙間を形成した状態で、当該芯金から弾性管を抜き取ることで、弾性管の内周面が傷付けられるのを防止している。   Further, in Patent Document 2, although it is not injection molding, vulcanization is performed in a state in which a material having elasticity such as raw rubber is wound around the surface of a cored bar in which innumerable through-holes are formed through inner and outer peripheral surfaces. After forming a cylindrical elastic tube by supplying a pressurized fluid to the inside of the core metal, a slight gap is formed between the core metal and the cylindrical elastic tube through an infinite number of through holes. In the formed state, by pulling out the elastic tube from the core metal, the inner peripheral surface of the elastic tube is prevented from being damaged.

特開平８−１７１９号公報JP-A-8-1719 特開２０００−８９７号公報Japanese Patent Laid-Open No. 2000-897

本発明は、抜取り方向の一端部のみが開放された筒状又は袋状の成形品を熱可塑性樹脂で射出成形した後に、成形型を構成する中子型から前記成形品を損傷することなく抜き取ることを課題としている。   In the present invention, after a cylindrical or bag-shaped molded product having only one end portion in the extraction direction opened by injection molding with a thermoplastic resin, the molded product is extracted from the core mold constituting the molding mold without damaging the molded product. It is an issue.

上記の課題を解決するための請求項１の発明は、ロッド状の中子型と、当該中子型の周囲を取り囲んで配置することでキャビティを形成するための複数の割型とから成り、前記キャビティに、溶融状の熱可塑性樹脂を射出して、抜取り方向の一端部のみが開放された筒状又は袋状の成形品を成形した後に、前記割型を中子型から離間させて、当該成形品を前記中子型から抜き取る構成の射出成形型であって、
前記中子型の内部のロッド挿通孔には、前記成形品の抜取り用のエジェクタピンが、圧縮空気の流通隙間を有した状態で挿通可能に挿入され、当該エジェクタピンの先端部は、前記中子型の先端部に対して、射出成形時には嵌合して気密を保持すると共に、成形品の抜取り時には、エジェクタピンの抜取り方向への押出しにより、前記嵌合が解除されて、当該中子型の外周面と成形品の内周面とで形成される抜取り隙間と、前記流通隙間とを連通する連通隙間が形成されるように嵌合及びその解除が可能になっていることを特徴としている。 The invention of claim 1 for solving the above-mentioned problem comprises a rod-shaped core mold and a plurality of split molds for forming a cavity by surrounding the core mold, After injecting a molten thermoplastic resin into the cavity and forming a cylindrical or bag-shaped molded product in which only one end in the extraction direction is opened, the split mold is separated from the core mold, An injection mold having a configuration in which the molded product is extracted from the core mold,
An ejector pin for extracting the molded product is inserted into the rod insertion hole inside the core mold so that the ejector pin can be inserted in a state having a flow gap for compressed air. At the time of injection molding, it is fitted and kept airtight with respect to the tip of the core mold, and at the time of extraction of the molded product, the fitting is released by pushing out the ejector pin in the extraction direction, and the core mold It is characterized in that fitting and releasing are possible so as to form a drawing gap formed by the outer circumferential surface of the molded article and the inner circumferential surface of the molded product and a communication gap that communicates the flow gap. .

請求項１の発明によれば、中子型と、当該中子型を取り囲むように配置された割型とで形成されるキャビティに溶融状の熱可塑性樹脂を射出して、所定時間経過することで、当該熱可塑性樹脂が固化した後に、複数の割型を中子型に対して離間させると、抜取り方向の一端部のみが開放された筒状又は袋状の成形品は、中子型の外周を覆った状態となっている。なお、成形状態では、中子型のロッド挿通孔に挿通されたエジェクタピンの先端部は、当該中子型の先端部に気密を保持した状態で、抜取り方向に押出し可能に嵌合されているため、前記先端部と先端部との密着面から溶融状の熱可塑性樹脂が浸入することはない。   According to the first aspect of the present invention, the molten thermoplastic resin is injected into the cavity formed by the core mold and the split mold disposed so as to surround the core mold, and a predetermined time elapses. Then, after the thermoplastic resin is solidified, when the plurality of split molds are separated from the core mold, the cylindrical or bag-shaped molded product in which only one end portion in the extraction direction is opened is the core mold. The outer periphery is covered. In the molded state, the tip of the ejector pin inserted through the core-type rod insertion hole is fitted so as to be extrudable in the extraction direction while maintaining airtightness at the tip of the core. For this reason, the molten thermoplastic resin does not enter from the contact surface between the tip and the tip.

この状態で、中子型のロッド挿通孔と、当該ロッド挿通孔に挿通されたエジェクタピンとの間に形成された流通隙間に圧縮空気を供給した状態で、エジェクタピンを抜取り方向に押し出すと、エジェクタピンの先端部と中子型の先端部との嵌合が解除されることで、両者の間に連通隙間が形成され、前記圧縮空気は、当該連通隙間を通して、中子型の外周面と、成形品の内周面との間に供給されて、成形品が僅かに膨らんで、両面の間に抜取り隙間が形成されて、抜取り抵抗が小さくなる。成形品は、熱可塑性樹脂で成形されていて、弾性を有するため、内面に圧縮空気が作用することで、膨らみ易い。このため、エジェクタピンを抜取り方向に押し出すと、成形品は、その閉塞部の内側がエジェクタピンで押されることで、筒状又は袋状の成形品は、僅かに膨らんだ状態を維持することで、損傷されることなく、中子型からスムーズに抜き取られる。   In this state, when the ejector pin is pushed out in the extraction direction while compressed air is supplied to the flow gap formed between the core-type rod insertion hole and the ejector pin inserted into the rod insertion hole, the ejector By releasing the fitting between the tip of the pin and the tip of the core type, a communication gap is formed between them, and the compressed air passes through the communication gap, and the outer peripheral surface of the core type, It is supplied between the inner peripheral surface of the molded product and the molded product slightly swells to form a extraction gap between both surfaces, thereby reducing the extraction resistance. Since the molded product is molded from a thermoplastic resin and has elasticity, it easily swells when compressed air acts on the inner surface. For this reason, when the ejector pin is pushed out in the pulling direction, the molded product is pushed by the ejector pin inside the closing portion, so that the cylindrical or bag-shaped molded product maintains a slightly swollen state. It can be removed smoothly from the core mold without being damaged.

よって、抜取り方向に沿った横断面形状が変化して、抜取り方向の一部にアンダーカット部を有する成形品であっても、抜取り時に、圧縮空気により成形品が膨らむことで、成形品は、損傷させることなく中子型から迅速に抜き取ることができて、成形品の生産性が高められる。このように、抜取り方向の一部にアンダーカット部を有する成形品の場合には、成形品の当該アンダーカット部を大きく膨らませる必要があるため、熱可塑性樹脂としては、ゴム弾性を有するエラストマーを使用する必要がある。   Therefore, even if the cross-sectional shape along the extraction direction is changed and the molded product has an undercut part in a part of the extraction direction, the molded product is expanded by compressed air at the time of extraction. The product can be quickly extracted from the core mold without being damaged, and the productivity of the molded product is increased. Thus, in the case of a molded product having an undercut portion in a part of the extraction direction, it is necessary to greatly inflate the undercut portion of the molded product. Therefore, an elastomer having rubber elasticity is used as the thermoplastic resin. Need to use.

一方、抜取り方向に沿った横断面形状が一定の成形品の場合には、圧縮空気により成形品が僅かに膨らむことで、中子型に抜き勾配を設けなくても、当該中子型からの成形品を損傷させることなく抜き取ることが可能となり、成形品の生産性が高められる。また、熱可塑性樹脂は、必ずしもゴム弾性を有するエラストマーでなくても、一般の熱可塑性樹脂による成形が可能となる。   On the other hand, in the case of a molded product having a constant cross-sectional shape along the extraction direction, the molded product is slightly swollen by compressed air, so that even if a draft is not provided in the core mold, It becomes possible to extract the molded product without damaging it, and the productivity of the molded product is improved. Moreover, even if the thermoplastic resin is not necessarily an elastomer having rubber elasticity, molding with a general thermoplastic resin is possible.

請求項２の発明は、請求項１の発明において、前記エジェクタピンの先端部は、逆円錐台状に形成されて嵌合凸部となっていると共に、前記中子型の先端部は、前記ロッド挿通孔と連続する中空逆円錐台状に形成されて被嵌合凹部となっていることを特徴としている。   According to a second aspect of the present invention, in the first aspect of the invention, the tip of the ejector pin is formed in an inverted frustoconical shape to be a fitting convex portion, and the tip of the core type is It is characterized in that it is formed in a hollow inverted frustoconical shape that is continuous with the rod insertion hole to be a fitted recess.

請求項２の発明によれば、エジェクタピンの先端部の逆円錐台状の嵌合凸部が、中子型の先端部の中空逆円錐台状の被嵌合凹部に嵌合される構成であるので、エジェクタピンが抜取り方向に押し出すことで形成される連通隙間は、成形品の閉塞部に臨んでいるため、成形品は、当該閉塞部を含めた全部位において、中子型との間に抜取り隙間が形成されるため、成形品を損傷させないで抜き取ることが、一層容易になると共に、中子型の横断面形状、即ち成形品の横断面形状とは無関係に、常に同一構造を適用できる利点がある。   According to the second aspect of the present invention, the inverted frustoconical fitting convex part at the tip of the ejector pin is fitted into the hollow inverted frustoconical fitting recessed part at the tip of the core type. Therefore, since the communication gap formed by pushing the ejector pin in the extraction direction faces the closed part of the molded product, the molded product is not connected to the core mold in all parts including the closed part. Since the extraction gap is formed in the mold, it is easier to extract without damaging the molded product, and the same structure is always applied regardless of the cross-sectional shape of the core mold, that is, the cross-sectional shape of the molded product. There are advantages you can do.

請求項３の発明は、請求項１の発明において、前記中子型の先端外周部は、縦断面が円錐台状に形成されて嵌合凸部となっていると共に、前記エジェクタピンの先端部には、前記中子型の横断面形状に対応する傘状部が形成されて、当該傘状部の内面側外周部は、縦断面が中空円錐台状に形成されて被嵌合凹部となっていることを特徴としている。   According to a third aspect of the present invention, in the first aspect of the invention, the outer peripheral portion of the tip of the core type has a longitudinal section formed in a truncated cone shape to be a fitting convex portion, and a distal end portion of the ejector pin Is formed with an umbrella-shaped portion corresponding to the cross-sectional shape of the core type, and the inner peripheral side outer peripheral portion of the umbrella-shaped portion is formed in a hollow truncated cone shape to become a fitted recess. It is characterized by having.

請求項３の発明によれば、圧縮空気により成形品が僅かに膨らませられることで、当該成形品の抜取りが容易になることに加えて、エジェクタピンの先端部の傘状部が、成形品の閉塞部の内面に全面に当たった状態で、中子型から当該成形品が抜き取られるために、当該成形品の抜取りを、一層に安定した状態で損傷することなく行える。   According to the invention of claim 3, since the molded product is slightly inflated by the compressed air, the molded product can be easily removed, and the umbrella-shaped portion at the tip of the ejector pin is formed of the molded product. Since the molded product is extracted from the core mold in a state where the inner surface of the closed portion is in contact with the entire surface, the molded product can be extracted in a more stable state without being damaged.

請求項４の発明は、請求項１ないし３のいずれかに記載の射出成形型の中子型を用いて、抜取り方向の一端部のみが開放された筒状又は袋状の成形品を射出成形する方法であって、
前記成形品の抜取り時には、前記エジェクタピンを抜取り方向に押し出して、前記流通隙間に供給された圧縮空気が、前記連通隙間を通して中子型の外周面と成形品の内周面との間に供給されることで、前記中子型に対して成形品を僅かに膨らませて抜取り隙間を形成して、当該成形品を抜き取ることを特徴としている。 A fourth aspect of the present invention is an injection molding of a cylindrical or bag-shaped molded product in which only one end portion in the drawing direction is opened by using the core mold of the injection molding mold according to any one of the first to third aspects. A way to
When the molded product is extracted, the ejector pin is pushed out in the extraction direction, and the compressed air supplied to the flow gap is supplied between the outer peripheral surface of the core mold and the inner peripheral surface of the molded product through the communication gap. Thus, the molded product is slightly inflated with respect to the core mold to form an extraction gap, and the molded product is extracted.

請求項４の発明は、請求項１ないし３のいずれかの発明を、成形品の抜取り方法を主体にした「射出成形方法」の面から把握したものであって、その抜取り作用は、請求項１ないし３の各発明で説明した通りである。   The invention of claim 4 grasps the invention of any one of claims 1 to 3 from the aspect of an “injection molding method” mainly based on a method of extracting a molded product, and the extraction action thereof is claimed in claim As described in the first to third inventions.

請求項５の発明は、請求項４の発明において、前記熱可塑性樹脂は、熱可塑性エラストマーであることを特徴としている。   The invention of claim 5 is the invention of claim 4, characterized in that the thermoplastic resin is a thermoplastic elastomer.

請求項５の発明のように、熱可塑性樹脂として熱可塑性エラストマーを使用した場合には、樹脂自体がゴム弾性を有しているため、中子型の外周面と成形品の内周面との間に圧縮空気が供給されることで、当該成形品が膨らみ易いため、中子型の外周面と成形品の内周面との間に抜取り隙間が成形され易くなって、本発明を実施し易くなる。   When a thermoplastic elastomer is used as the thermoplastic resin as in the invention of claim 5, since the resin itself has rubber elasticity, the outer peripheral surface of the core mold and the inner peripheral surface of the molded product Since the molded product easily swells due to the supply of compressed air, the extraction gap is easily formed between the outer peripheral surface of the core mold and the inner peripheral surface of the molded product, and the present invention is carried out. It becomes easy.

本発明によれば、射出成形後の中子型の外側を成形品が覆った状態において、エジェクタピンを抜取り方向に押し出すと、エジェクタピンの先端部と中子型の先端部との嵌合が解除されることで、両者の間に連通隙間が形成されて、流通隙間に供給された圧縮空気は、前記連通隙間を通して、中子型の外周面と、成形品の内周面との間に供給されて、成形品が僅かに膨らんで、両面の間に抜取り隙間が形成され、抜取り抵抗が小さくなると共に、成形品は、熱可塑性樹脂で成形されていて、弾性を有するため、内面に圧縮空気が作用することで、弾性変形して膨らむ。   According to the present invention, when the ejector pin is pushed out in the extraction direction in a state where the outer side of the core mold after the injection molding is covered, the fitting between the tip of the ejector pin and the tip of the core mold is performed. By being released, a communication gap is formed between them, and the compressed air supplied to the flow gap passes through the communication gap between the outer peripheral surface of the core mold and the inner peripheral surface of the molded product. When the molded product is slightly inflated, an extraction gap is formed between both surfaces, the extraction resistance is reduced, and the molded product is molded with a thermoplastic resin and has elasticity, so it is compressed on the inner surface. When air acts, it is elastically deformed and swells.

このため、エジェクタピンを抜取り方向に押し出すと、成形品は、その閉塞部の内側がエジェクタピンで押されることで、筒状又は袋状の成形品は、抜取り方向に沿ってアンダーカット部を有していても、僅かに膨らんだ状態を維持することで、損傷されることなく、中子型からスムーズに抜き取られる。また、横断面形状が全長に亘って同一の円筒状の成形品の場合には、中子型に抜き勾配を設けなくても、当該中子型の外周面との間に、圧縮空気による抜取り隙間が形成されることで、成形品は、損傷されることなく中子型から迅速に抜き取ることが可能となる。なお、成形状態では、中子型のロッド挿通孔に挿通されたエジェクタピンの先端部は、当該中子型の先端部に気密を保持した状態で、抜取り方向に押出し可能に嵌合されているため、前記先端部と先端部との密着面から溶融状の熱可塑性樹脂が浸入することはない。   For this reason, when the ejector pin is pushed out in the extraction direction, the molded product is pushed by the ejector pin inside the closed portion, so that the cylindrical or bag-shaped molded product has an undercut portion along the extraction direction. Even if it is, it can be smoothly extracted from the core mold without being damaged by maintaining the slightly swollen state. Moreover, in the case of a cylindrical molded product having the same cross-sectional shape over the entire length, extraction with compressed air is performed between the core mold and the outer peripheral surface without providing a draft angle. By forming the gap, the molded product can be quickly extracted from the core mold without being damaged. In the molded state, the tip of the ejector pin inserted through the core-type rod insertion hole is fitted so as to be extrudable in the extraction direction while maintaining airtightness at the tip of the core. For this reason, the molten thermoplastic resin does not enter from the contact surface between the tip and the tip.

一対の割型Ｂ1 ，Ｂ2 の正面図（図３のＸ−Ｘ線矢視図）である。It is a front view of a pair of split molds B 1, B 2 (X- X sectional view taken along line of FIG. 3). 一対の割型Ｂ1 ，Ｂ2 が閉じて、中子型Ａ1 との間に形成されたキャビティＣに溶融状の熱可塑性エラストマーが射出される状態の射出成形型Ｋの縦断面図（図１のＹ−Ｙ線断面図）である。A longitudinal sectional view of an injection mold K in a state in which a pair of split molds B 1 and B 2 are closed and molten thermoplastic elastomer is injected into a cavity C formed between the core mold A 1 (FIG. 1 is a sectional view taken along line YY in FIG. 射出成形後に、各割型Ｂ1 ，Ｂ2 を中子型Ａ1 に対して離間させると共に、固定型Ｄと可動型Ｍとを分離させたた状態の射出成形型Ｋの縦断面図である。FIG. 4 is a longitudinal sectional view of an injection mold K in a state where the split molds B 1 and B 2 are separated from the core mold A 1 and the fixed mold D and the movable mold M are separated after injection molding. . 圧縮空気の作用により、成形品Ｐ1 の内周面と中子型Ａ1 の外周面との間に圧縮空気を供給して、当該成形品Ｐ1 を僅かに膨らませて、エジェクタピンＥ1 の押出しにより、中子型Ａ1 から成形品Ｐ1 を抜き取る状態を示す射出成形型Ｋの縦断面図である。By the action of compressed air, by supplying compressed air between the inner and outer circumferential surfaces of the core type A 1 of the molded article P 1, the molded product P 1 is inflated slightly, the ejector pin E 1 by extrusion, it is a longitudinal sectional view of the injection mold K which indicates a state of extracting the molded article P 1 from core mold a 1. エジェクタピンＥ1 が僅かに抜取り方向に押し出して、成形品Ｐ1 の内周面と中子型Ａ1 の外周面との間に圧縮空気が供給されて、中子型Ａ1 に対して成形品Ｐ1 が僅かに膨らんだ状態の中子型Ａ1 の縦断面図である。Ejector pin E 1 is extruded in the direction extraction slightly, compressed air is supplied between the inner and outer circumferential surfaces of the core type A 1 of the molded article P 1, molded to the core die A 1 It is a longitudinal cross-sectional view of the core mold A 1 in a state where the product P 1 is slightly swollen. （ａ），（ｂ）は、それぞれ図３のＺ1 −Ｚ1 線及び図５のＺ2 −Ｚ2 線の各拡大断面図である。(A), (b) are each a enlarged sectional view of the Z 2 -Z 2-wire Z 1 -Z 1 line and 5, respectively, of FIG 3. （ａ），（ｂ）は、それぞれ全長に亘って外径が同一であって、外径に対して長さが比較的長い円筒状の成形品Ｐ2 の抜取り前後の縦断面図である。(A), (b), the outer diameter over the entire length respectively are the same, it is a longitudinal sectional view of the front and rear removal of the molded article P 2 length to the outer diameter of relatively long cylindrical. （ａ），（ｂ）は、それぞれ引抜きの手前側から奥側に向けて外径が漸次小さくなる逆テーパー円筒状の成形品Ｐ3 を中子型Ａ2 から抜き取る前後の縦断面図である。(A), (b) is a vertical sectional view before and after extracting the molded product P 3 of the reverse taper cylindrical outer diameter of gradually smaller toward the respective front side of the pull on the far side from the middle mold A 2 . （ａ），（ｂ）は、それぞれ本発明により成形可能な別の成形品Ｐ4 の斜視図及び縦断面図である。(A), (b) are a perspective view and a longitudinal sectional view of the molded article P 4 of another formable by the present invention, respectively.

以下、複数の実施例を挙げて、本発明について更に詳細に説明する。最初に、本発明を実施するための射出成形型Ｋについて説明し、その後に射出成形方法について説明する。なお、割型をスライドさせる機構は、アンギュラピンによる方法、シリンダーによる方法等が知られているが、本実施例では、アンギュラピンを使用した射出成形型Ｋについて説明する。   Hereinafter, the present invention will be described in more detail with reference to a plurality of examples. First, an injection mold K for carrying out the present invention will be described, and then an injection molding method will be described. As the mechanism for sliding the split mold, a method using an angular pin, a method using a cylinder, and the like are known. In this embodiment, an injection mold K using an angular pin will be described.

実施例１の射出成形型Ｋは、固定型Ｄと、可動型Ｍとから成る。可動型Ｍは、図１〜図５に示されるように、正面視で方形状をなす剛体構造のテーブル台Ｔが側板１に複数本の支柱２を介してベース台３が垂直に支持され、方形状のベース台３における一対の割型Ｂ1 ，Ｂ2 のスライド方向Ｑの中央部に、中子型Ａ1 が垂直となって一体に支持され、ベース台３におるけ中子型Ａ1 の両側に、一対の割型Ｂ1 ，Ｂ2 が互いに接近・離間するように、水平方向にスライド可能に支持された構成である。当該構成の可動型Ｍの全体が固定型Ｄに対して接近・離間するように移動する。 The injection mold K according to the first embodiment includes a fixed mold D and a movable mold M. As shown in FIGS. 1 to 5, in the movable mold M, the base table 3 is vertically supported on the side plate 1 via a plurality of support columns 2 on a table base T having a rigid structure that is square in front view. The core mold A 1 is vertically supported integrally at the center of the pair of split molds B 1 and B 2 in the sliding direction Q of the rectangular base base 3, and the core mold A in the base base 3 is supported. A pair of split molds B 1 and B 2 are supported on both sides of 1 so as to be slidable in the horizontal direction so as to approach and separate from each other. The entire movable mold M configured as described above moves so as to approach and separate from the fixed mold D.

前記可動型Ｍにおいて、ベース台３に支持された一対の割型Ｂ1 ，Ｂ2 は、接近端位置（合***置）と離間端位置との間で、互いに接近及び離間するようにスライドされる。固定型Ｄの型本体４には、一対の割型Ｂ1 ，Ｂ2 を接近端位置において、合***置の各割型Ｂ1 ，Ｂ2 の型本体５の外側に嵌合される中空円錐台状の型嵌合凹部６が側方に開口して形成されており、方形状の型本体４の各コーナー部よりも僅かに内側の部分には、一対で一組となった二組である計４本の傾斜アンギュラピン７が下方に突出して設けられている。各組の２本の傾斜アンギュラピン７は、水平面内に配置されて、基端から先端に向けて間隔を広くなるように傾斜した状態で大きく下方に突出している。固定型Ｄの一対一組となった二組の傾斜アンギュラピン７は、一対の割型Ｂ1 ，Ｂ2 の外周部の厚肉フランジ部８に貫通形成された傾斜ガイド孔１１にそれぞれ挿通される構造になっている。よって、図１及び図２に示されるように、固定型Ｄの二組の傾斜アンギュラピン７が、一対の割型Ｂ1 ，Ｂ2 の各傾斜ガイド孔１１に挿通された状態で、可動型Ｍの全体を固定型Ｄに対して水平方向にスライドさせると、一対の割型Ｂ1 ，Ｂ2 は、互いに離間したり、接近したりする。固定型Ｄには、溶融状の熱可塑性エラストマーを射出させるスプルーブッシュ１２が埋め込まれている。なお、成形品Ｐ1 の抜取りのための空間を確保するため、図３及び図４に示されるように、一対の割型Ｂ1 ，Ｂ2 の離間時には、固定型Ｄの一対の傾斜アンギュラピン７が、各割型Ｂ1 ，Ｂ2 の各傾斜ガイド孔１１から脱出することで、固定型Ｄに対して可動型Ｍは分離される。 In the movable mold M, the pair of split molds B 1 and B 2 supported by the base table 3 are slid so as to approach and separate from each other between the approach end position (merged position) and the separation end position. . The mold body 4 of the fixed mold D, the hollow truncated cone at the approach end position a pair of split molds B 1, B 2, which is fitted on the outside of the split type B 1, B 2 of the mold body 5 of the united position The shape-shaped mold fitting recess 6 is formed so as to open to the side, and there are two pairs that are a pair in a portion slightly inside the corner portions of the square-shaped mold body 4. A total of four inclined angular pins 7 are provided protruding downward. The two inclined angular pins 7 of each set are arranged in a horizontal plane and project greatly downward in a state where they are inclined so as to be widened from the proximal end toward the distal end. The two sets of inclined angular pins 7 that are a pair of fixed molds D are respectively inserted into inclined guide holes 11 formed through the thick flange portions 8 on the outer peripheral portions of the pair of split molds B 1 and B 2. It has a structure. Therefore, as shown in FIGS. 1 and 2, the two sets of inclined angular pins 7 of the fixed mold D are inserted into the inclined guide holes 11 of the pair of split molds B 1 and B 2 , and are movable. When the whole M is slid in the horizontal direction with respect to the fixed mold D, the pair of split molds B 1 and B 2 are separated from each other or approach each other. A sprue bush 12 for injecting a molten thermoplastic elastomer is embedded in the fixed mold D. In order to secure a space for extracting the molded product P 1 , as shown in FIGS. 3 and 4, when the pair of split molds B 1 and B 2 are separated from each other, the pair of inclined angular pins of the fixed mold D is used. 7 escapes from each inclined guide hole 11 of each split mold B 1 , B 2 , so that the movable mold M is separated from the fixed mold D.

そして、図１に示されるように、一対の割型Ｂ1 ，Ｂ2 が最も接近して各型本体５が台形台状に合体した部分が、固定型Ｄの型嵌合凹部６に嵌合されることで、前記中子型Ａ1 の外周面と、各割型Ｂ1 ，Ｂ2 の内周面とで形成される空間がキャビティ（成形空間）Ｃとなる。なお、キャビティＣが形成された状態では、各割型Ｂ1 ，Ｂ2 により、当該キャビティＣに連通する短いランナ１３が形成される。 Then, as shown in FIG. 1, the part where the pair of split molds B 1 and B 2 are closest to each other and the mold main bodies 5 are combined into a trapezoidal trapezoidal shape is fitted into the mold fitting recess 6 of the fixed mold D. As a result, a space formed by the outer peripheral surface of the core mold A 1 and the inner peripheral surfaces of the split molds B 1 and B 2 becomes a cavity (molding space) C. In the state where the cavity C is formed, the short runner 13 communicating with the cavity C is formed by the split dies B 1 and B 2 .

成形品Ｐ1 は、抜取り方向に沿った横断面形状は大きく異なっていて、抜取り方向の途中にアンダーカット部を有していて、抜取り方向に沿った一端部のみが開放された変則円筒状又は変則袋状をなしている。即ち、成形品Ｐ1 は、抜取り方向の全体が閉塞されて、他端部のみが開口され、開放端部には、一般円筒部Ｐ1aの外径よりも遥かに大きな外径を有していて、縦断面が等脚逆台形状の端末嵌着部Ｐ1cが形成され、本実施例では、符号Ｐ1a, Ｐ1e, Ｐ1cで示される部分がアンダーカット構造となっている。中子型Ａ1 は、当該成形品Ｐ1 の内周形状と同一である。中子型Ａ1 の横断面の中央部には、エジェクタピンＥ1 が挿通されるロッド挿通孔２１が貫通して形成され、前記ベース台３には、前記エジェクタピンＥ1 の押出しを支持する支持ブッシュ２２が埋設され、当該ロッド挿通孔２１及び支持ブッシュ２２にエジェクタピンＥ1 が挿通されている。ロッド挿通孔２１の内径は、エジェクタピンＥ1 の外径よりも僅かに大きく形成されて、当該ロッド挿通孔２１にエジェクタピンＥ1 を挿通した状態で、当該エジェクタピンＥ1 の外周面と、ロッド挿通孔２１の内周面との間に形成される隙間は、圧縮空気が流通する流通隙間Ｓ1 となっている。当該流通隙間Ｓ1 における支持ブッシュ２２に近い部分には、中子型Ａ1 及びベース台３に貫通して形成された圧縮空気孔２３が接続され、当該圧縮空気孔２３を通して外部の圧縮空気源から流通隙間Ｓ1 に圧縮空気が供給される。なお、中子型Ａ1 のロッド挿通孔２１の内径と、エジェクタピンＥ1 の外径との差は、圧縮空気が必要な速度を有して流通して得ることが必要であり、例えば１ｍｍ程度である。 The molded product P 1 has a greatly different cross-sectional shape along the extraction direction, has an undercut part in the middle of the extraction direction, and has an irregular cylindrical shape in which only one end along the extraction direction is opened or It has an irregular bag shape. That is, the entire molded product P 1 is closed in the extraction direction, only the other end is opened, and the open end has an outer diameter much larger than the outer diameter of the general cylindrical portion P 1 a. Thus, a terminal fitting portion P 1 c having an isosceles inverted trapezoidal longitudinal section is formed, and in this embodiment, the portions indicated by the symbols P 1 a, P 1 e, and P 1 c have an undercut structure. ing. The core mold A 1 is the same as the inner peripheral shape of the molded product P 1 . A rod insertion hole 21 through which the ejector pin E 1 is inserted is formed at the center of the transverse cross section of the core mold A 1 , and the base table 3 supports the extrusion of the ejector pin E 1. A support bush 22 is embedded, and an ejector pin E 1 is inserted through the rod insertion hole 21 and the support bush 22. The inner diameter of the rod insertion hole 21, and than the outer diameter of the ejector pin E 1 is formed slightly larger, in a state of inserting the ejector pin E 1 to the rod insertion hole 21, the outer peripheral surface of the ejector pin E 1, gap formed between the inner peripheral surface of the rod insertion hole 21, compressed air has a flow gap S 1 flowing. A compressed air hole 23 formed through the core mold A 1 and the base 3 is connected to a portion close to the support bush 22 in the flow gap S 1. An external compressed air source is connected through the compressed air hole 23. compressed air is supplied to the flow gap S 1 from. The difference between the inner diameter of the rod insertion hole 21 of the core type A 1 and the outer diameter of the ejector pin E 1 must be obtained by circulating compressed air at a necessary speed, for example, 1 mm. Degree.

前記エジェクタピンＥ1 の先端部は、縦断面が逆円錐台状に形成された嵌合凸部２４となっていて、中子型Ａ1 に形成された前記ロッド挿通孔２１の先端部は、当該エジェクタピンＥ1 の嵌合凸部２４が隙間なく嵌合されて密着する中空逆円錐台状の嵌合凹部２５となっている。このため、図３、図５及び図６に示されるように、エジェクタピンＥ1 が後退端に達している状態では、エジェクタピンＥ1 の先端部の嵌合凸部２４が、中子型Ａ1 の先端部の嵌合凹部２５に隙間なく嵌合されることで、互いの円錐面が密着し合うことで、溶融状の熱可塑性エラストマーが浸入不能な構造になっている〔図３及び図６（ａ）〕。一方、エジェクタピンＥ1 が、後方の後退端から成形品Ｐ1 の抜取り方向に僅かに押し出すと、エジェクタピンＥ1 の嵌合凸部２４の外円錐面２４ａと、中子型Ａ1 の嵌合凹部２５の内円錐面２５ａとの間に僅かの隙間が形成される。この隙間は、前記流通隙間Ｓ1 と、成形品Ｐ1 の内周面と中子型Ａ1 の外周面との間に供給された圧縮空気により形成される抜取り隙間Ｓ3 とを連通する連通隙間Ｓ2 となる。 The tip of the ejector pin E 1 is a fitting convex part 24 whose longitudinal section is formed in an inverted truncated cone shape, and the tip of the rod insertion hole 21 formed in the core mold A 1 is The fitting convex part 24 of the ejector pin E 1 is a hollow inverted frustoconical fitting concave part 25 that fits closely without gap. Therefore, as shown in FIGS. 3, 5, and 6, in a state where the ejector pin E 1 has reached the retracted end, the fitting convex portion 24 at the tip of the ejector pin E 1 is the core type A 1 is fitted into the fitting recess 25 of the tip portion without any gap, so that the conical surfaces of each other come into close contact with each other, so that a molten thermoplastic elastomer cannot be infiltrated [FIGS. 6 (a)]. On the other hand, when the ejector pin E 1 is slightly pushed out from the backward retracted end in the extraction direction of the molded product P 1 , the outer conical surface 24a of the fitting convex portion 24 of the ejector pin E 1 and the core mold A 1 are fitted. A slight gap is formed between the concavity 25 and the inner conical surface 25a. This gap communicates with the flow gap S 1 and the extraction gap S 3 formed by the compressed air supplied between the inner peripheral surface of the molded product P 1 and the outer peripheral surface of the core mold A 1. the gap S 2.

また、図２〜図４に示されるように、ベース台３の下方には、方形状のエジェクタプレート２６が複数のガイドピン（図示せず）により垂直を維持して、水平方向にスライド可能に配置されている。エジェクタプレート２６は、押しロッド２７により押されて、当該押しロッド２７により前記エジェクタプレート２６を介して前記エジェクタピンＥ1 を抜取り方向に沿って押し出す。 As shown in FIGS. 2 to 4, a rectangular ejector plate 26 is maintained vertically by a plurality of guide pins (not shown) below the base table 3 and is slidable in the horizontal direction. Has been placed. Ejector plate 26 is pushed by the push rod 27, via the ejector plate 26 by the push rod 27 pushes in a direction withdrawing the ejector pin E 1.

そして、固定型Ｄの各傾斜アンギュラピン７が一対の割型Ｂ1 ，Ｂ2 の各傾斜ガイド孔１１に挿入された状態で、固定型Ｄに対して可動型Ｍを前進させると、一対の割型Ｂ1 ，Ｂ2 が互いに近接して、図１及び図２に示されるように、各型合せ面２８，２９（図１参照）が互いに密着して、一対の割型Ｂ1 ，Ｂ2 が合体して、固定型Ｄの型嵌合凹部６に嵌合されることで、中子型Ａ1 の外周面と、合体された各割型Ｂ1 ，Ｂ2 の内周面との間に、成形品Ｐ1 の形状に対応したキャビティＣが形成される。この成形状態では、エジェクタピンＥ1 が取付けられたエジェクタプレート２６は、リターンピン（図示せず）により最後退端に押されることで、エジェクタピンＥ1 も、最も後方の後退端位置に配置されて、その先端の嵌合凸部２４は、中子型Ａ1 の先端部に形成された嵌合凹部２５に隙間なく嵌合されることで、溶融状の熱可塑性エラストマーが浸入しないようになっている。 Then, when the movable mold M is moved forward with respect to the fixed mold D in a state where the respective inclined angular pins 7 of the fixed mold D are inserted into the respective inclined guide holes 11 of the pair of split molds B 1 and B 2 , The split molds B 1 and B 2 are close to each other, and as shown in FIGS. 1 and 2, the mold matching surfaces 28 and 29 (see FIG. 1) are in close contact with each other, and a pair of split molds B 1 and B 2 2 are united and fitted into the mold fitting recess 6 of the fixed mold D, so that the outer peripheral surface of the core mold A 1 and the inner peripheral surface of each of the combined split molds B 1 and B 2 In the meantime, a cavity C corresponding to the shape of the molded product P 1 is formed. In this molded state, the ejector plate 26 to which the ejector pin E 1 is attached is pushed to the last retracted end by a return pin (not shown), so that the ejector pin E 1 is also disposed at the most backward retracted end position. Then, the fitting convex portion 24 at the tip is fitted into the fitting concave portion 25 formed at the tip portion of the core mold A 1 without any gap, so that the molten thermoplastic elastomer does not enter. ing.

上記の状態で、スプルーブッシュ１２に形成されたスプルー１２ａ及びランナ１３を通して、樹脂原料射出装置のノズル５１から、溶融状の熱可塑性エラストマーが前記キャビティＣに射出される。所定時間が経過して、射出された熱可塑性エラストマーが冷却固化した後に、可動型Ｍを後退させると、図３に示されるように、一対の割型Ｂ1 ，Ｂ2 が互いに離間されて、中子型Ａ1 の外周面に成形された円筒状の成形品Ｐ1 が露出される。なお、図３〜図５において、４１は、スプルー１２ａ及びランナ１３で成形品Ｐ1 と一体に形成された非製品部であり、中子型Ａ1 から成形品Ｐ1 を抜き取った後に、当該成形品Ｐ1 を型外に取り出す際に、成形品Ｐ1 に接触することなく掴むのに使用される。 In the above state, molten thermoplastic elastomer is injected into the cavity C from the nozzle 51 of the resin raw material injection device through the sprue 12 a and the runner 13 formed in the sprue bush 12. After the predetermined time has elapsed and the injected thermoplastic elastomer has cooled and solidified, when the movable mold M is retracted, the pair of split molds B 1 and B 2 are separated from each other as shown in FIG. The cylindrical molded product P 1 molded on the outer peripheral surface of the core mold A 1 is exposed. 3 to 5, reference numeral 41 denotes a non-product part integrally formed with the molded product P 1 by the sprue 12 a and the runner 13, and after the molded product P 1 is extracted from the core mold A 1 , When the molded product P 1 is taken out of the mold, the molded product P 1 is used for gripping without contacting the molded product P 1 .

中子型Ａ1 の外周面に成形品Ｐ1 が覆い被せられて成形された状態で、ベース台３及び中子型Ａ1 に形成された圧縮空気孔２３から流通隙間Ｓ1 に圧縮空気が供給されている状態において、押しロッド２７によりエジェクタピンＥ1 を成形品Ｐ1 の抜取り方向に押し出すと、図５及び図６に示されるように、中子型Ａ1 の上端部の嵌合凹部２５の内円錐面２５ａと、エジェクタピンＥ1 の嵌合凸部２４の外円錐面２４ａとの間に連通隙間Ｓ2 が形成され、流通隙間Ｓ1 に供給された圧縮空気は、当該連通隙間Ｓ2 を通して、中子型Ａ1 の外周面と成形品Ｐ1 の内周面との間に供給されることで、熱可塑性エラストマーから成る成形品Ｐ1 がゴム弾性変形により外側に膨らむことで、両面の間に抜取り隙間Ｓ3 が形成される。 In a state where the molded article P 1 is molded is overmolded on the outer peripheral surface of the core type A 1, compressed air from the base table 3 and the core die A compressed air hole 23 formed in 1 to flow gap S 1 is When the ejector pin E 1 is pushed out by the push rod 27 in the removal direction of the molded product P 1 in the supplied state, as shown in FIGS. 5 and 6, the fitting recess at the upper end of the core mold A 1 is used. 25, a communication gap S 2 is formed between the inner conical surface 25a and the outer cone surface 24a of the fitting projection 24 of the ejector pin E 1. The compressed air supplied to the flow gap S 1 through S 2, it is supplied between the outer peripheral surface of the core die a 1 and the inner circumferential surface of the molded article P 1, that the molded product P 1 of a thermoplastic elastomer swells outward by elastic deformation , the clearance S 3 extraction between both sides is formed.

エジェクタピンＥ1 は、その先端部の嵌合凸部２４が、成形品Ｐ1 の閉塞部Ｐ1bの内周面に当たった状態で、抜取り方向に押し出すことで、成形品Ｐ1 は、中子型Ａ1 の外周面との間に抜取り隙間Ｓ3 が形成された状態で抜き取られるために、当該中子型Ａ1 の外周面に対する摺動抵抗がなくなるか、或いは極めて小さな摺動抵抗のため、当該成形品Ｐ1 は、損傷されることなく、スムーズに中子型Ａ1 から抜き取られる。なお、図４で実線で示されるように、中子型Ａ1 に対して成形品Ｐ1 の閉塞部Ｐ1bの側の部分が所定長だけ抜き取られた後には、流通隙間Ｓ1 から噴出される圧縮空気は、成形品Ｐ1 の抜取り部の内部空間に充満された状態を維持して、前記抜取り隙間Ｓ3 を通って成形品Ｐ1 の外部に排出される。このため、成形品Ｐ1 は、その開口側に端末嵌着部Ｐ1cが形成されていたり、中子型Ａ1 には、成形品Ｐ1 の膨出部Ｐ1dを形成するための膨出部Ａ1aが存在していても、抜取り隙間Ｓ3 を連続して流れる圧縮空気により、成形品Ｐ1 の各部が膨らむために、中子型Ａ1 に対して摺動した場合でも、その摺動抵抗は小さくなるため、成形品Ｐ1 は、中子型Ａ1 から殆ど損傷されることなくスムーズに抜き取られる。 Ejector pin E 1 is convex portion 24 fitting of the tip, while striking the inner circumferential surface of the closing portion P 1 b of the molded article P 1, by extruding the removal direction, the molded article P 1 is to be withdrawn in a state where a gap S 3 is formed withdrawal between an outer peripheral surface of the core type a 1, or the sliding resistance with respect to the outer peripheral surface of the core mold a 1 is eliminated, or very small sliding resistance Therefore, the molded product P 1 is smoothly extracted from the core mold A 1 without being damaged. In addition, as shown by the solid line in FIG. 4, after the portion on the closed portion P 1 b side of the molded product P 1 is extracted from the core mold A 1 by a predetermined length, it is ejected from the flow gap S 1. The compressed air to be discharged is discharged to the outside of the molded product P 1 through the extraction gap S 3 while maintaining a state in which the internal space of the extraction part of the molded product P 1 is filled. Therefore, the molded product P 1 has a terminal fitting portion P 1 c formed on the opening side, or the core mold A 1 for forming the bulging portion P 1 d of the molded product P 1 . Even if the bulging portion A 1 a exists, even if the portion of the molded product P 1 swells due to the compressed air continuously flowing through the extraction gap S 3 , even when sliding with respect to the core mold A 1 Since the sliding resistance is reduced, the molded product P 1 can be smoothly extracted from the core mold A 1 with almost no damage.

このように、抜取り方向に沿った横断面形状が随所で変化していて、しかも抜取り方向に沿った一部にアンダーカット部を有する変則円筒状又は変則袋状の成形品Ｐ1 であっても、成形品Ｐ1 は、ゴム弾性を有する熱可塑性エラストマーで成形されているため、抜取り時に、圧縮空気の作用による膨み量を大きく確保できて、中子型Ａ1 の外周面との間に、抜取りに必要な抜取り隙間Ｓ3 が形成されるため、成形品Ｐ1 は、損傷されることなく、中子型Ａ1 から迅速に抜き取ることが可能となって、生産性が高められる。また、実施例１のように、抜取り方向の途中にアンダーカット部Ｐ1eを有する成形品Ｐ1 では、当該成形品Ｐ1 の膨み量を大きくする必要があるため、熱可塑性樹脂は、ゴム弾性を有するエラストマーであることが必要である。なお、成形対象のアンダーカット部を有する筒状又は袋状の成形品の横断面形状は、円形以外に任意の形状であっても、抜取り可能である。 As described above, even if the cross-sectional shape along the extraction direction is changed everywhere, and the irregularly cylindrical or irregular bag-shaped molded product P 1 having an undercut portion at a part along the extraction direction, Since the molded product P 1 is molded from a thermoplastic elastomer having rubber elasticity, a large amount of swelling due to the action of compressed air can be secured at the time of extraction, and between the outer peripheral surface of the core mold A 1. Since the extraction gap S 3 necessary for extraction is formed, the molded product P 1 can be quickly extracted from the core mold A 1 without being damaged, and the productivity is improved. Further, as in Example 1, in the molded product P 1 having the undercut portion P 1 e in the middle of the extraction direction, it is necessary to increase the amount of swelling of the molded product P 1 . It is necessary to be an elastomer having rubber elasticity. In addition, even if the cross-sectional shape of the cylindrical or bag-shaped molded product having an undercut part to be molded is an arbitrary shape other than a circle, it can be extracted.

また、図７（ａ），（ｂ）は、全長に亘って一定の外径であって、しかも外径に対して長さが比較的長くて、抜取り方向の一端部のみが開放された円筒状の成形品Ｐ2 を中子型Ａ2 から抜き取る前後の縦断面図である。中子型Ａ2 は、成形品Ｐ2 の形状に対応して、抜き勾配が設けられずに、全長に亘って横断面形状が一定の円筒状を成していて、内部のロッド挿通孔２１には、上記したエジェクタピンＥ1 が挿通されている。このような形状の成形品Ｐ2 は、外径に対して長さが長いために、中子型Ａ2 との総接触面積が大きくなって、当該成形品Ｐ2 を抜き取る際の中子型Ａ2 に対する摺動抵抗が大きくなり、その結果、抜取りが困難であり、仮に抜き取ることができても、成形品Ｐ2 が損傷され易い。更に、成形品Ｐ2 の抜取りを可能にするために、中子型Ａ2 の外周面に抜き勾配を設けると、外径が一定の場合には、成形品Ｐ2 の肉厚は、抜取り方向の先端から基端に向けて、漸次薄くなり、全長に亘って一定の肉厚が要求される場合には、対応できない。 7 (a) and 7 (b) are cylinders that have a constant outer diameter over the entire length, are relatively long with respect to the outer diameter, and are open only at one end in the extraction direction. Jo of the molded article P 2 is a longitudinal sectional view of the front and rear withdrawn from the core type a 2. Corresponding to the shape of the molded product P 2 , the core mold A 2 is not provided with a draft angle, and has a cylindrical shape with a constant cross-sectional shape over the entire length. The above-described ejector pin E 1 is inserted into the cable. Since the molded product P 2 having such a shape has a long length with respect to the outer diameter, the total contact area with the core mold A 2 becomes large, and the core mold when the molded product P 2 is extracted. As a result, the sliding resistance against A 2 increases, and as a result, extraction is difficult, and even if it can be extracted, the molded product P 2 is easily damaged. Further, when a draft is provided on the outer peripheral surface of the core mold A 2 in order to allow the molded product P 2 to be extracted, the thickness of the molded product P 2 is determined in the sampling direction when the outer diameter is constant. This is not possible in the case where the thickness gradually decreases from the distal end to the proximal end and a constant thickness is required over the entire length.

実施例２では、使用樹脂は、ゴム弾性を有する熱可塑性エラストマーでなくても、一般の熱可塑性樹脂であっても、成形可能である。溶融状で射出された熱可塑性樹脂が冷却固化した状態において、流通隙間Ｓ1 に圧縮空気を供給した状態で、エジェクタピンＥ1 を抜取り方向に押し出して、成形品Ｐ2 の抜取りを開始すると、エジェクタピンＥ1 の先端部の嵌合凸部２４と、中子型Ａ2 の先端部の嵌合凹部２５との間に連通隙間Ｓ2 が形成され、当該連通隙間Ｓ2 を通して、中子型Ａ2 の外周面と成形品Ｐ2 の内周面との間に圧縮空気が供給されて、両面の間に、空気層による微小な抜取り隙間Ｓ3 が、成形品Ｐ2 の全長に亘って形成される。一般の熱可塑性樹脂であっても、僅かに弾性変形し得るため、連通隙間Ｓ2 に供給された圧縮空気により僅かに膨らんで、抜取り隙間Ｓ3 が形成される。このため、中子型Ａ2 に対する成形品Ｐ2 の摺動抵抗が皆無となるか、或いは極めて小さくなって、外径に対して長さの長い成形品Ｐ2 を損傷することなく、スムーズに抜き取ることが可能となる。 In Example 2, even if the resin used is not a thermoplastic elastomer having rubber elasticity, it can be molded even if it is a general thermoplastic resin. In a state where the thermoplastic resin injected in a molten state is cooled and solidified, the ejector pin E 1 is pushed out in the extraction direction in a state where compressed air is supplied to the flow gap S 1 , and extraction of the molded product P 2 is started. A communication gap S 2 is formed between the fitting convex part 24 at the tip of the ejector pin E 1 and the fitting concave part 25 at the tip of the core mold A 2 , and the core mold passes through the communication gap S 2. Compressed air is supplied between the outer peripheral surface of A 2 and the inner peripheral surface of the molded product P 2 , and a minute extraction gap S 3 due to the air layer extends over the entire length of the molded product P 2 between both surfaces. It is formed. Even a general thermoplastic resin can be slightly elastically deformed, so that it is slightly swelled by the compressed air supplied to the communication gap S 2 to form the extraction gap S 3 . For this reason, the sliding resistance of the molded product P 2 with respect to the core mold A 2 is completely eliminated or becomes extremely small without causing damage to the molded product P 2 having a long length with respect to the outer diameter. It can be extracted.

このように、抜取り方向に沿った一端部のみが開放されて、全長に亘って一定の横断面形状を有する円筒状の成形品Ｐ2 の射出成形では、圧縮空気により中子型Ａ2 の外周面との間に抜取り隙間Ｓ3 が形成されるため、中子型Ａ2 に抜き勾配を設けなくても成形可能であるのみならず、円筒状の成形品Ｐ2 は、全長に亘って一定の肉厚を確保できて、当該中子型Ａ2 から全く損傷させないで、しかも迅速に抜き取ることが可能となるので、成形品Ｐ2 の生産性が高められる。特に、成形品Ｐ2 のように、全長に亘って同一の横断面形状の場合には、原料樹脂である熱可塑性樹脂は、ゴム弾性を有するエラストマーに限られず、ゴム弾性を有しない一般の熱可塑性樹脂の使用も可能となる。なお、筒状の成形品の横断面形状、及び横断面の外径寸法に対する長さの比は、いかなるものであっても、成形可能である。 Thus, in the injection molding of the cylindrical molded product P 2 having only one end portion along the extraction direction and having a constant cross-sectional shape over the entire length, the outer periphery of the core mold A 2 is compressed by compressed air. Since the extraction gap S 3 is formed between the surface and the surface, not only can the core mold A 2 be molded without a draft, but the cylindrical molded product P 2 is constant over the entire length. Can be secured without being damaged from the core mold A 2 at all, and can be quickly extracted, thereby increasing the productivity of the molded product P 2 . In particular, as the molded article P 2, in the case of the same cross-sectional shape over the entire length, the thermoplastic resin which is a raw material resin is not limited to elastomers having rubber elasticity, generally heat no rubber elasticity The use of a plastic resin is also possible. In addition, it can shape | mold whatever the ratio of the length with respect to the cross-sectional shape of a cylindrical molded product and the outer diameter dimension of a cross-section.

次に、図８を参照して、本発明の実施例３について説明する。なお、樹脂材料は、ゴム弾性を有するエラストマーを使用している。図８（ａ），（ｂ）は、それぞれ引抜きの手前側から奥側に向けて外径が漸次小さくなる逆テーパー円筒状の成形品Ｐ3 を中子型Ａ2 から抜き取る前後の縦断面図である。中子型Ａ2 は、先端部から基端部に向けて外径が漸次小さくなるような逆テーパー円筒状に形成されて、軸心部に挿通孔３１が形成され、先端外周部は、縦断面が円錐台状に形成されて嵌合凸部３２となっている。中子型Ａ2 のロッド挿通孔３１に挿通されるエジェクタピンＥ2 の先端部は、当該中子型Ａ2 の先端部の外径と同一の傘状部３３が形成され、当該傘状部３３の内面側外周部は、縦断面が中空円錐台状に形成された被嵌合凹部３４となっていて、エジェクタピンＥ2 の被嵌合凹部３４に、中子型Ａ2 の嵌合凸部３２が隙間なく密着した状態で嵌合、及びその解除が可能となっている。このため、射出成形時に、エジェクタピンＥ2 の傘状部３３に対して任意の方向の射出圧が作用しても、中子型Ａ2 に対してエジェクタピンＥ2 の傘状部３３が位置ずれしないため、成形品の成形精度を確保できる。 Next, Embodiment 3 of the present invention will be described with reference to FIG. The resin material uses an elastomer having rubber elasticity. 8A and 8B are longitudinal sectional views before and after extracting from the core mold A 2 a reverse tapered cylindrical shaped product P 3 whose outer diameter gradually decreases from the front side to the back side of the drawing. It is. The core mold A 2 is formed in a reverse tapered cylindrical shape whose outer diameter gradually decreases from the distal end portion toward the proximal end portion, and an insertion hole 31 is formed in the axial center portion. The surface is formed in a truncated cone shape to form a fitting convex portion 32. Tip of the ejector pin E 2 to be inserted into the rod insertion hole 31 of the core die A 2 are identical cone-shaped part 33 and the outer diameter of the tip portion of the core mold A 2 are formed, the cone-shaped part The outer peripheral side of the inner surface 33 is a fitted recess 34 whose longitudinal section is formed in the shape of a hollow truncated cone, and the fitted protrusion 34 of the core type A 2 is fitted into the fitted recess 34 of the ejector pin E 2. The fitting and the release thereof are possible with the portion 32 in close contact with the gap. Therefore, at the time of injection molding, also act injection pressure of any direction relative to the cone-shaped part 33 of the ejector pin E 2, position the cone-shaped part 33 of the ejector pin E 2 is relative to the core die A 2 Since it does not shift, the molding accuracy of the molded product can be secured.

このため、エジェクタピンＥ2 の抜取り方向への押出しにより、エジェクタピンＥ2 の被嵌合凹部３４と、中子型Ａ2 の嵌合凸部３２との嵌合が解除されると、被嵌合凹部３４と嵌合凸部３２との間に隙間が形成され、当該隙間は、流通隙間Ｓ1 に供給されている圧縮空気が通って、中子型Ａ2 の外周面と成形品Ｐ3 の内周面との間に供給されて抜取り隙間Ｓ3 を形成するための連通隙間Ｓ2 となる。 For this reason, when the fitting between the fitting concave portion 34 of the ejector pin E 2 and the fitting convex portion 32 of the core mold A 2 is released by pushing the ejector pin E 2 in the extraction direction, the fitting is performed. a gap is formed between the engagement recess 34 and the fitting convex portion 32, the gap, the flow gap compressed air through which is supplied to S 1, the outer peripheral surface and the molded article P 3 of the core type a 2 The communication gap S 2 is formed between the inner peripheral surface and the extraction gap S 3 .

よって、成形品Ｐ3 の成形後において、流通隙間Ｓ1 に圧縮空気を供給した状態で、エジェクタピンＥ2 を抜取り方向に押し出して、中子型Ａ2 の嵌合凸部３２とエジェクタピンＥ2 の被嵌合凹部３４との間に連通隙間Ｓ2 が形成されると、当該連通隙間Ｓ2 を通って、中子型Ａ2 の外周面と成形品Ｐ3 の内周面との間に圧縮空気が供給されて、中子型Ａ2 の外周面と成形品Ｐ3 の内周面との間に抜取り隙間Ｓ3 が形成されるので、成形品Ｐ3 が逆テーパー円筒状をなしていても、成形品Ｐ3 が外側に膨らむことで、中子型Ａ2 に対して非接触又は僅かに接触した状態で、中子型Ａ2 から成形品Ｐ3 が抜き取られる。 Therefore, after molding the molded product P 3 , the ejector pin E 2 is pushed out in the extraction direction in a state where compressed air is supplied to the flow gap S 1 , and the fitting convex portion 32 and the ejector pin E of the core mold A 2 are pushed out. When the communication gap S 2 is formed between the two fitted recesses 34, the gap between the outer peripheral surface of the core mold A 2 and the inner peripheral surface of the molded product P 3 passes through the communication gap S 2. to be supplied with compressed air, since the gap S 3 extraction between an outer peripheral surface of the core die a 2 and the inner peripheral surface of the molded article P 3 is formed, the molded article P 3 an inverted tapered cylindrical Even if the molded product P 3 swells outward, the molded product P 3 is extracted from the core mold A 2 in a non-contact state or a slight contact with the core mold A 2 .

また、本発明の射出成形方法により成形可能な成形品は、抜取り方向又は抜取り方向に沿って一端部のみが開放された筒状であることが条件であるが、上記したような円筒状に限られず、図９に示されるような引抜き方向に沿って逆テーパー状の角筒部を有する四角筒状の成形品Ｐ4 であっても成形可能である。 In addition, the molded product that can be molded by the injection molding method of the present invention is in the drawing direction or a cylindrical shape in which only one end is opened along the drawing direction, but is not limited to the cylindrical shape as described above. However, even a quadrangular tubular molded product P 4 having a reverse-tapered square tubular portion along the drawing direction as shown in FIG. 9 can be molded.

なお、実施例３，４の閉塞端部から開口端部に向けて逆テーパー状となった前記成形品Ｐ3 ，Ｐ4 も、成形品の抜取りの面からみると、アンダーカット構造であると言える。 It should be noted that the molded products P 3 and P 4 having a reverse taper shape from the closed end portion to the open end portion in Examples 3 and 4 also have an undercut structure when viewed from the surface of the molded product extraction. I can say that.

Ａ1 ，Ａ2 ：中子型
Ｂ1 ，Ｂ2 ：割型
Ｃ：キャビティ
Ｄ：固定型
Ｅ1 ，Ｅ2 ：エジェクタピン
Ｋ：射出成形型
Ｍ：可動型
Ｐ1 〜Ｐ4 ：成形品
Ｐ1e：成形品のアンダーカット部
Ｓ1 ：流通隙間
Ｓ2 ：連通隙間
Ｓ3 ：抜取り隙間
２４：嵌合凸部（エジェクタピンの先端部）
２５：嵌合凹部（中子型の先端部）
３１：ロッド挿通孔
３２：嵌合凸部（中子型の先端部）
３３：傘状部
３４：被嵌合凹部（エジェクタピンの先端部） A 1 , A 2 : Core type B 1 , B 2 : Split type
C: Cavity
D: Fixed type E 1 , E 2 : Ejector pin
K: Injection mold
M: movable die P 1 to P 4: moldings
P 1 e: Undercut part of the molded product
S 1 : Distribution gap
S 2 : Communication gap
S 3: sampling gap
24: Fitting protrusion (tip of ejector pin)
25: Fitting recess (core tip)
31: Rod insertion hole
32: Fitting protrusion (core-shaped tip)
33: Umbrella-shaped part
34: recessed portion to be fitted (tip end of ejector pin)

Claims (5)

ロッド状の中子型と、当該中子型の周囲を取り囲んで配置することでキャビティを形成するための複数の割型とから成り、前記キャビティに、溶融状の熱可塑性樹脂を射出して、抜取り方向の一端部のみが開放された筒状又は袋状の成形品を成形した後に、前記割型を中子型から離間させて、当該成形品を前記中子型から抜き取る構成の射出成形型であって、
前記中子型の内部のロッド挿通孔には、前記成形品の抜取り用のエジェクタピンが、圧縮空気の流通隙間を有した状態で挿通可能に挿入され、当該エジェクタピンの先端部は、前記中子型の先端部に対して、射出成形時には嵌合して気密を保持すると共に、成形品の抜取り時には、エジェクタピンの抜取り方向への押出しにより、前記嵌合が解除されて、当該中子型の外周面と成形品の内周面とで形成される抜取り隙間と、前記流通隙間とを連通する連通隙間が形成されるように嵌合及びその解除が可能になっていることを特徴とする射出成形型の中子型。 It consists of a rod-shaped core mold and a plurality of split molds for forming a cavity by surrounding the core mold, and injecting a molten thermoplastic resin into the cavity, An injection mold having a configuration in which after forming a cylindrical or bag-shaped molded product in which only one end in the extraction direction is opened, the split mold is separated from the core mold and the molded product is extracted from the core mold. Because
An ejector pin for extracting the molded product is inserted into the rod insertion hole inside the core mold so that the ejector pin can be inserted in a state having a flow gap for compressed air. At the time of injection molding, it is fitted and kept airtight with respect to the tip of the core mold, and at the time of extraction of the molded product, the fitting is released by pushing out the ejector pin in the extraction direction, and the core mold It is possible to fit and release so that a drawing gap formed by the outer peripheral surface of the molded product and the inner peripheral surface of the molded product and a communication gap that connects the flow gap are formed. Core mold for injection molds. 前記エジェクタピンの先端部は、逆円錐台状に形成されて嵌合凸部となっていると共に、前記中子型の先端部は、前記ロッド挿通孔と連続する中空逆円錐台状に形成されて被嵌合凹部となっていることを特徴とする請求項１に記載の射出成形型の中子型。   The tip of the ejector pin is formed in an inverted frustoconical shape to be a fitting convex portion, and the tip of the core type is formed in a hollow inverted frustoconical shape that is continuous with the rod insertion hole. The core mold of the injection mold according to claim 1, wherein the core mold is a fitted recess. 前記中子型の先端外周部は、縦断面が円錐台状に形成されて嵌合凸部となっていると共に、前記エジェクタピンの先端部には、前記中子型の横断面形状に対応する傘状部が形成されて、当該傘状部の内面側外周部は、縦断面が中空円錐台状に形成されて被嵌合凹部となっていることを特徴とする請求項１に記載の射出成形型の中子型。   The outer periphery of the tip of the core type has a vertical cross section formed in a truncated cone shape to be a fitting convex portion, and the tip of the ejector pin corresponds to the cross sectional shape of the core type. 2. The injection according to claim 1, wherein an umbrella-shaped portion is formed, and an outer peripheral portion on the inner surface side of the umbrella-shaped portion is formed in a hollow truncated cone shape to be a fitted recess. Core mold for molds. 請求項１ないし３のいずれかに記載の射出成形型の中子型を用いて、抜取り方向の一端部のみが開放された筒状又は袋状の成形品を射出成形する方法であって、
前記成形品の抜取り時には、前記エジェクタピンを抜取り方向に押し出して、前記流通隙間に供給された圧縮空気が、前記連通隙間を通して中子型の外周面と成形品の内周面との間に供給されることで、前記中子型に対して成形品を僅かに膨らませて抜取り隙間を形成して、当該成形品を抜き取ることを特徴とする射出成形方法。 A method of injection-molding a cylindrical or bag-shaped molded article having only one end portion in the drawing direction opened using the core mold of the injection mold according to any one of claims 1 to 3,
When the molded product is extracted, the ejector pin is pushed out in the extraction direction, and the compressed air supplied to the flow gap is supplied between the outer peripheral surface of the core mold and the inner peripheral surface of the molded product through the communication gap. Thus, an injection molding method characterized in that the molded product is slightly inflated with respect to the core mold to form an extraction gap, and the molded product is extracted. 前記熱可塑性樹脂は、熱可塑性エラストマーであることを特徴とする請求項４に記載の射出成形方法。   The injection molding method according to claim 4, wherein the thermoplastic resin is a thermoplastic elastomer.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112976508A (en) * 2021-02-08 2021-06-18 柏祝美 Mould for injection moulding
CN115556309A (en) * 2022-09-16 2023-01-03 温州意华接插件股份有限公司 Barb plastic part mold and demolding method thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112976508A (en) * 2021-02-08 2021-06-18 柏祝美 Mould for injection moulding
CN112976508B (en) * 2021-02-08 2022-06-28 宁波利宝来汽车部件科技有限公司 Mould for injection moulding
CN115556309A (en) * 2022-09-16 2023-01-03 温州意华接插件股份有限公司 Barb plastic part mold and demolding method thereof
CN115556309B (en) * 2022-09-16 2024-04-09 温州意华接插件股份有限公司 Barb plastic part mold and demolding method thereof

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