JP2010094867A - Injection molding die for cylindrical molding, injection molding method, and molding - Google Patents

Injection molding die for cylindrical molding, injection molding method, and molding Download PDF

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JP2010094867A
JP2010094867A JP2008266321A JP2008266321A JP2010094867A JP 2010094867 A JP2010094867 A JP 2010094867A JP 2008266321 A JP2008266321 A JP 2008266321A JP 2008266321 A JP2008266321 A JP 2008266321A JP 2010094867 A JP2010094867 A JP 2010094867A
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mold
core pin
molded product
molding
molding die
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JP5317053B2 (en
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Shigeru Hatano
成 波多野
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SABIC Innovative Plastics Japan KK
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<P>PROBLEM TO BE SOLVED: To provide an injection molding die capable of obtaining a cylindrical molding with satisfactory dimensional precision. <P>SOLUTION: This injection molding die has a fixed side molding die and a movable side molding die, at least one of the fixed side molding die and the movable side molding die has a core pin for forming an inner face of a molding, and a full length of the core pin is 10-80% of a thickness of the molding die in a side having the core pin. The present invention provides also a molding die of which the core pin is constituted of a material having heat conductivity lower by 10-99% than a material constituting other member for forming a cavity, and also a molding die of which the core pin has a heat insulation portion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、熱可塑性樹脂の成形により円筒状成形品を得るための射出成形用金型、これを用いた射出成形方法及び成形品に関する。特に、高い寸法精度を要求される円筒状成形品の成形に適する射出成形用金型、これを用いた射出成形方法及び成形品に関する。 The present invention relates to an injection mold for obtaining a cylindrical molded product by molding a thermoplastic resin, an injection molding method using the mold, and a molded product. In particular, the present invention relates to an injection mold suitable for molding a cylindrical molded product requiring high dimensional accuracy, an injection molding method using the mold, and a molded product.

熱可塑性樹脂からなる成形品は、射出成形により極めて容易に効率よくかつ安価に製造することができることから、金属製に代わって広く利用されている。しかし、樹脂の成形品は一般に、金属を切削加工して得られる製品に比べて、寸法精度に劣る。高い寸法精度、特に真円度(円形部分の、幾何学的に正しい円からの狂いの大きさ;一定断面円の各直径の偏り)および円筒度(円筒部分の、幾何学的に正しい円筒からの狂いの大きさ;円筒の長さ方向に見たときの各断面円の大きさ(直径)の差)が要求される円筒状の成形品においては、これが重大な問題となる。 Molded articles made of thermoplastic resins are widely used in place of metal because they can be manufactured very easily, efficiently and inexpensively by injection molding. However, resin molded products are generally inferior in dimensional accuracy compared to products obtained by cutting metal. High dimensional accuracy, especially roundness (magnitude of deviation from the geometrically correct circle of the circular part; deviation of each diameter of the constant cross-sectional circle) and cylindricity (from the geometrically correct cylinder of the cylindrical part) This is a serious problem in a cylindrical molded product that requires a difference in size (diameter) of each cross-sectional circle when viewed in the length direction of the cylinder.

そこで、円筒状成形品の内面を形成するコアピンを有する金型を用いて樹脂を射出成形するとき、コアピンを冷却することにより、樹脂から放出される熱がコアピンに蓄積するのを緩和して寸法精度を高めることが従来行われている。さらに、キャビティ先端部に近接する金型接合面に断熱層を設けることにより、円筒状成形品の先端部の冷却固化を抑制して、精度(特に成形品の外面の円筒度)のより高い成形品を得ることが提案されている(例えば特許文献1)。 Therefore, when resin is injection molded using a mold having a core pin that forms the inner surface of a cylindrical molded product, the core pin is cooled to reduce the heat released from the resin from accumulating in the core pin. Conventionally, the accuracy is improved. Furthermore, by providing a heat insulating layer on the die joint surface close to the cavity tip, cooling and solidification of the tip of the cylindrical molded product is suppressed, and molding with higher accuracy (particularly the cylindricity of the outer surface of the molded product) is achieved. It has been proposed to obtain a product (for example, Patent Document 1).

また、高精度の円筒状成形品を効率よく得ることを目的として、コアピンを固定金型に設けることによりコアピンの十分な冷却を容易に行うことが提案されている(例えば特許文献2)。 In addition, for the purpose of efficiently obtaining a high-precision cylindrical molded product, it has been proposed to sufficiently cool the core pin by providing the core pin in a fixed mold (for example, Patent Document 2).

一方、成形材料としてフィラー入りの樹脂(特に非晶性樹脂)を使用すると、材料の線膨張率が小さくなり、したがって良好な寸法精度を有する成形品が得られることが知られている。しかし、フィラー入り樹脂を使用して円筒状成形品を成形するとき、その寸法精度は十分でない。
特開平1−263016号公報 特開平5−138693号公報
On the other hand, it is known that when a resin containing a filler (particularly an amorphous resin) is used as a molding material, the linear expansion coefficient of the material is reduced, and thus a molded product having good dimensional accuracy can be obtained. However, when a cylindrical molded product is molded using a resin containing filler, the dimensional accuracy is not sufficient.
Japanese Patent Laid-Open No. 1-263016 JP-A-5-138893

本発明者は、上記事情に鑑みて、高い寸法精度を有する円筒状成形品の成形に適する射出成形用金型を提供すべく、特に、フィラー入り樹脂を使用して円筒状成形品を成形しても、十分な寸法精度の成形品を得ることができる金型を提供すべく鋭意検討した。そして、フィラー入り樹脂を使用したときに十分な寸法精度が得られない原因が、円筒状成形品の外面に比べて、内面でのフィラーの浮き上がりが大きく、内面の真円度及び円筒度が悪化するためであることが見出され、上記浮き上がりの原因として、以下のことが見出された。 In view of the above circumstances, the present inventor, in order to provide an injection mold suitable for molding a cylindrical molded product having a high dimensional accuracy, in particular, molded a cylindrical molded product using a filler-filled resin. However, intensive studies were conducted to provide a mold capable of obtaining a molded product with sufficient dimensional accuracy. And the reason why sufficient dimensional accuracy cannot be obtained when using resin with filler is that the float of the filler on the inner surface is larger than the outer surface of the cylindrical molded product, and the roundness and cylindricity of the inner surface are deteriorated. The following were found as the causes of the above-mentioned lifting.

円筒状成形品を射出成形する場合、例えば図2に示されるように、成形品の取り出しをエジェクタースリーブによって行うことが一般的である。図2に示されるように、コアピン2はその周囲にエジェクタースリーブ6を有し、エジェクタースリーブはコアピンに沿って前後に摺動する部品であるので、エジェクタースリーブ内側にあるコアピンや、エジェクタースリーブ外側にある他の部材との間に隙間がある。従って、通常の金型温調回路を設けても(例えば図2のプレート7に加熱用のヒートパイプを設けても)、その熱はコアピンに伝わり難い。したがって、コアピンはキャビティに充填される樹脂からしか熱をもらえない。さらに、スリーブ突き出しの機構上、コアピンは長くなり(図2に示されるように、コアピンの全長(L)は通常、可動側金型の厚み(T)の100%以上である)、したがって、熱容量が大きくなるとともに放熱しやすくなるため、コアピンの温度を、フィラーの浮き上がりを防ぐのに必要な温度に上昇させ難くなる。 When a cylindrical molded product is injection-molded, for example, as shown in FIG. 2, it is common to take out the molded product with an ejector sleeve. As shown in FIG. 2, the core pin 2 has an ejector sleeve 6 around it, and the ejector sleeve is a part that slides back and forth along the core pin. Therefore, the core pin 2 is provided inside the ejector sleeve and outside the ejector sleeve. There is a gap between some other member. Therefore, even if a normal mold temperature control circuit is provided (for example, a heat pipe for heating is provided on the plate 7 in FIG. 2), the heat is hardly transmitted to the core pin. Therefore, the core pin can receive heat only from the resin filled in the cavity. Furthermore, the core pin becomes longer due to the mechanism of sleeve protrusion (as shown in FIG. 2, the total length (L) of the core pin is usually 100% or more of the thickness (T) of the movable mold), and therefore the heat capacity However, it becomes difficult to raise the temperature of the core pin to a temperature necessary for preventing the filler from being lifted.

本発明者は、コアピンの全長を短くすると、コアピンの熱容量が小さくなるとともにコアピンから放出される熱量が少なくなり、上記目的が達成されることを見出した。従来は、コアピンの温度が上がり過ぎて成形品の寸法精度が不十分になるという問題があり、コアピンを冷却することにより上記問題を解決していた。しかし、本発明は、成形樹脂としてフィラー入り樹脂を使用する場合には、逆に、コアピンを高温に保つようにする必要があることを見出したことに基づく。 The present inventor has found that when the total length of the core pin is shortened, the heat capacity of the core pin is reduced and the amount of heat released from the core pin is reduced, thereby achieving the above object. Conventionally, there has been a problem that the temperature of the core pin is too high and the dimensional accuracy of the molded product becomes insufficient, and the above problem has been solved by cooling the core pin. However, the present invention is based on the finding that it is necessary to keep the core pin at a high temperature when using a resin containing filler as the molding resin.

すなわち、本発明は、円筒状成形品の射出成形用金型において、固定側金型および可動側金型を有し、固定側金型および可動側金型の少なくとも一方が、成形品の内面を形成するコアピンを有し、コアピンの全長が、上記コアピンを有する側の金型の厚みの10〜80%であることを特徴とする金型を提供する。
また、本発明は、円筒状成形品の射出成形用金型において、固定側金型および可動側金型を有し、固定側金型および可動側金型の少なくとも一方が、成形品の内面を形成するコアピンを有し、コアピンを構成する材料が、キャビティを形成する他の部材を構成する材料よりも10〜99%低い熱伝導率を有することを特徴とする金型を提供する。
また、本発明は、円筒状成形品の射出成形用金型において、固定側金型および可動側金型を有し、固定側金型および可動側金型の少なくとも一方が、成形品の内面を形成するコアピンを有し、コアピンが断熱部分を有することを特徴とする金型を提供する。
That is, the present invention provides a cylindrical molded product injection mold having a fixed mold and a movable mold, and at least one of the fixed mold and the movable mold has an inner surface of the molded product. Provided is a mold having a core pin to be formed, wherein the total length of the core pin is 10 to 80% of the thickness of the mold on the side having the core pin.
In addition, the present invention provides a cylindrical molded product injection mold having a fixed mold and a movable mold, wherein at least one of the fixed mold and the movable mold has an inner surface of the molded product. There is provided a mold having a core pin to be formed, and a material constituting the core pin having a thermal conductivity lower by 10 to 99% than a material constituting another member forming the cavity.
In addition, the present invention provides a cylindrical molded product injection mold having a fixed mold and a movable mold, wherein at least one of the fixed mold and the movable mold has an inner surface of the molded product. A mold having a core pin to be formed and the core pin having a heat insulating portion is provided.

本発明の射出成形用金型は、円筒状の成形品を高精度で得ることができ、成形樹脂としてフィラー入り樹脂を使用しても、成形品の内面でのフィラーの浮き上がりを生じることなく、高い寸法精度を有する円筒状成形品を得ることができる。したがって、スピンドルモーターのスリーブ等の高い寸法精度を要求される円筒形状の部品の製造に好適に使用できる。 The mold for injection molding of the present invention can obtain a cylindrical molded product with high accuracy, and even if a resin containing a filler is used as a molding resin, the filler does not float on the inner surface of the molded product, A cylindrical molded product having high dimensional accuracy can be obtained. Therefore, it can be suitably used for the manufacture of cylindrical parts that require high dimensional accuracy, such as spindle motor sleeves.

以下に、本発明の金型を、図を参照して説明する。なお、本発明の金型は射出成形用である。射出成形は、樹脂を金型内に射出する射出工程と、金型内で樹脂を冷却する冷却工程と、金型を開いて成形品を取り出す取り出し工程とを含む成形法である。 Below, the metal mold | die of this invention is demonstrated with reference to figures. The mold of the present invention is for injection molding. The injection molding is a molding method including an injection process for injecting a resin into a mold, a cooling process for cooling the resin in the mold, and a taking-out process for opening the mold and taking out a molded product.

本発明の第1の態様における金型は、固定側金型および可動側金型を有し、固定側金型および可動側金型の少なくとも一方がコアピンを有し、上記コアピンの全長(L)が上記コアピンを有する側の金型の厚み(T)の10〜80%、好ましくは20〜60%、より好ましくは30〜50%であるように構成される。具体的には、成形品の全長が10mm以下の場合には、コアピンの全長から成形品の長さを除いた長さが20〜100mm、好ましくは20〜50mmである。成形品の全長が10mmを超える場合には、コアピンの全長から成形品の長さを除いた長さが20〜150mm、好ましくは20〜75mmである。 The mold in the first aspect of the present invention has a fixed mold and a movable mold, and at least one of the fixed mold and the movable mold has a core pin, and the total length (L) of the core pin. Is 10 to 80%, preferably 20 to 60%, more preferably 30 to 50% of the thickness (T) of the mold having the core pin. Specifically, when the total length of the molded product is 10 mm or less, the length excluding the length of the molded product from the total length of the core pin is 20 to 100 mm, preferably 20 to 50 mm. When the total length of the molded product exceeds 10 mm, the length excluding the length of the molded product from the total length of the core pin is 20 to 150 mm, preferably 20 to 75 mm.

コアピン全長を上記のように短くすることができる金型として、図1および3に示す構造を有する金型が挙げられる。 A mold having the structure shown in FIGS. 1 and 3 can be cited as a mold that can shorten the entire length of the core pin as described above.

図1は、可動側金型がコアピンを有し、成形品の突き出しをエジェクタースリーブ機構によって行う場合の、本発明に従う金型を示す概略断面図である。図中、パーティングライン(PL)より上部が固定側金型4であり、PLと可動側プラテン13との間が可動側金型である。1は成形品であり、2は成形品の内面を形成するコアピンであり、3は成形品の胴部外面を形成する雌型であり、6はエジェクタースリーブである。コアピン2が、図2に示す従来の金型の場合と比べて、成形品により近いプレート(プレート8)に固定されている。こうすることにより、コアピンの全長を、従来の場合よりも短くすることができる。この場合、エジェクタースリーブは、図2と同様の可動機構にすることができない。なぜならば、コアピンの全長に合わせて可動側金型の厚みを単純に薄くすることができないからである。可動側金型は、ある程度の強度を必要とし、また、温度調節回路を設けるためのスペースを必要とする。そこで、図1に示すように、エジェクタースリーブ6とその後退機構であるスプリング9とを成型品1とコアピン固定プレート8との間に設け、エジェクタースリーブのフランジ部と連結した部材を介してエジェクタースリーブを可動させる機構にすることができる。この場合、上記可動は、従来と同様の成形機エジェクターロッド12を用いて行うことができる。 FIG. 1 is a schematic cross-sectional view showing a mold according to the present invention when the movable mold has a core pin and the molded product is ejected by an ejector sleeve mechanism. In the drawing, the upper part from the parting line (PL) is the fixed mold 4, and the space between the PL and the movable platen 13 is the movable mold. 1 is a molded product, 2 is a core pin that forms the inner surface of the molded product, 3 is a female mold that forms the outer surface of the body of the molded product, and 6 is an ejector sleeve. The core pin 2 is fixed to a plate (plate 8) closer to the molded product than in the case of the conventional mold shown in FIG. By doing so, the overall length of the core pin can be made shorter than in the conventional case. In this case, the ejector sleeve cannot be a movable mechanism similar to that shown in FIG. This is because it is not possible to simply reduce the thickness of the movable mold in accordance with the entire length of the core pin. The movable mold requires a certain level of strength and requires a space for providing a temperature control circuit. Therefore, as shown in FIG. 1, an ejector sleeve 6 and a spring 9 as a retraction mechanism thereof are provided between the molded product 1 and the core pin fixing plate 8, and the ejector sleeve is connected via a member connected to the flange portion of the ejector sleeve. The mechanism can be made to move. In this case, the above-mentioned movement can be performed by using the same molding machine ejector rod 12 as that of the prior art.

図1に関する上記説明では、エジェクターをスリーブ状として記載したが、エジェクターは、複数のピンで構成されていてもよい。 In the above description regarding FIG. 1, the ejector is described as a sleeve shape, but the ejector may be configured by a plurality of pins.

また、図1の金型において、スプリング9を設ける代わりに、スリーブとプレート10とを繋ぐ部材を中空にし、中空部分にボルトを貫通させて、エジェクタースリーブのフランジ部と締結することもできる。 In the mold shown in FIG. 1, instead of providing the spring 9, a member connecting the sleeve and the plate 10 can be made hollow, and a bolt can be passed through the hollow portion to be fastened to the flange portion of the ejector sleeve.

図1に示す構成の他に、図3に示す構成も、コアピン全長を短くすることができる。 In addition to the configuration shown in FIG. 1, the configuration shown in FIG. 3 can also shorten the overall length of the core pin.

図3は、可動側金型がコアピンを有し、成形品の突き出しをプレート突き出し機構によって行う場合の、本発明に従う金型を示す概略断面図であり、PLで金型を開いた状態を示す。図3の金型では、エジェクタースリーブ(またはエジェクターピン)を設ける代わりに、プレート5と成形機エジェクターロッド12とを直結し、プレート5を前進させることにより、成形品の突き出しが行われる。また、成形品の外面を形成する雌型3が固定側金型に設けられている。この金型は、エジェクタースリーブ(またはエジェクターピン)による突き出し機構を有しないので、コアピン全長を短くすることができる。このような金型では、図3に示すように金型を開いたとき、成形品が、成形品の外面を形成する雌型3からは離れるが、コアピン2には接触したままであるように、成形品のための樹脂を特定のものにしたり、コアピンの表面にアンダーカットをつけたりして成形が行われる。 FIG. 3 is a schematic cross-sectional view showing a mold according to the present invention when the movable mold has a core pin and the molded product is ejected by a plate ejecting mechanism, and shows a state where the mold is opened at PL. . In the mold of FIG. 3, instead of providing an ejector sleeve (or ejector pin), the plate 5 and the molding machine ejector rod 12 are directly connected, and the plate 5 is advanced, whereby the molded product is ejected. In addition, a female die 3 that forms the outer surface of the molded product is provided in the fixed-side die. Since this mold does not have a protruding mechanism by the ejector sleeve (or ejector pin), the entire length of the core pin can be shortened. In such a mold, when the mold is opened as shown in FIG. 3, the molded product is separated from the female mold 3 that forms the outer surface of the molded product, but remains in contact with the core pin 2. Molding is performed by making the resin for the molded product a specific one or by attaching an undercut to the surface of the core pin.

本発明の第2の態様における金型は、固定側金型および可動側金型を有し、固定側金型および可動側金型の少なくとも一方がコアピンを有し、コアピンを構成する材料が、キャビティを形成する他の部材を構成する材料よりも10〜99%低い、好ましくは20〜99%低い、より好ましくは30〜99%低い熱伝導率を有する。こうすることにより、コアピンからの熱の放出を抑えることができる。その結果、成形樹脂としてフィラー入り樹脂を使用しても、成形品の内面でのフィラーの浮き上がりを抑えることができ、円筒状成形品を良好な寸法精度で得ることができる。この第2の態様における金型の構成は、好ましくは、上記第1の態様における金型の構成と組み合わせられ得る。 The mold in the second aspect of the present invention has a fixed mold and a movable mold, at least one of the fixed mold and the movable mold has a core pin, and the material constituting the core pin is: It has a thermal conductivity that is 10 to 99% lower, preferably 20 to 99% lower, more preferably 30 to 99% lower than the material constituting the other members forming the cavity. By so doing, it is possible to suppress the release of heat from the core pin. As a result, even if filler-containing resin is used as the molding resin, the floating of the filler on the inner surface of the molded product can be suppressed, and a cylindrical molded product can be obtained with good dimensional accuracy. The configuration of the mold in the second aspect can be preferably combined with the configuration of the mold in the first aspect.

コアピンを構成する熱伝導性の低い材料としては、ステンレス鋼、セラミック材料(アルミナ、窒化珪素、ジルコニア等)などが挙げられ、キャビティを形成する他の部材のための熱伝導性の高い材料としては、炭素鋼などの一般鋼、ベリリウム鋼、銅、銅合金、窒化アルミニウムなどが挙げられる。 Stainless steel, ceramic materials (alumina, silicon nitride, zirconia, etc.) are examples of materials with low thermal conductivity that constitute the core pin. Examples of materials with high thermal conductivity for other members that form cavities include: And general steel such as carbon steel, beryllium steel, copper, copper alloy, and aluminum nitride.

本発明の第3の態様における金型は、固定側金型および可動側金型を有し、固定側金型および可動側金型の少なくとも一方がコアピンを有し、コアピンが断熱部分を有する。こうすることにより、コアピンからの熱の放出を抑えることができる。その結果、成形樹脂としてフィラー入り樹脂を使用しても、成形品の内面でのフィラーの浮き上がりを抑えることができ、円筒状成形品を良好な寸法精度で得ることができる。この第3の態様における金型の構成は、好ましくは、上記第1の態様における金型の構成および/または第2の態様における金型の構成と組みわせられ得る。 The mold in the third aspect of the present invention includes a fixed mold and a movable mold, at least one of the fixed mold and the movable mold includes a core pin, and the core pin includes a heat insulating portion. By so doing, it is possible to suppress the release of heat from the core pin. As a result, even if filler-containing resin is used as the molding resin, the floating of the filler on the inner surface of the molded product can be suppressed, and a cylindrical molded product can be obtained with good dimensional accuracy. The configuration of the mold in the third aspect can be preferably combined with the configuration of the mold in the first aspect and / or the configuration of the mold in the second aspect.

断熱部分を設ける方法として、例えば、図4に示すように、コアピン内で、他の部材と接触する個所に断熱溝16を設けたり、図5に示すように、コアピンを複数個に分割し、分割部分に断熱層18を設けたりする方法が挙げられる。断熱層は、コアピンを構成する材料よりも熱伝導性の低い材料、例えば熱伝導率が10W/m・K以下、更には1W/m・K以下の材料、で構成され得る。 As a method of providing a heat insulating part, for example, as shown in FIG. 4, in the core pin, a heat insulating groove 16 is provided at a place where it contacts other members, or as shown in FIG. 5, the core pin is divided into a plurality of parts. A method of providing the heat insulating layer 18 at the divided portion is mentioned. The heat insulating layer can be made of a material having a lower thermal conductivity than the material constituting the core pin, for example, a material having a thermal conductivity of 10 W / m · K or less, and further 1 W / m · K or less.

さらに、コアピンを加熱する手段を金型に設けて、コアピンの温度の低下を抑えることもできる。加熱手段を設ける方法としては、コアピンの内部および/または外部にヒーターを設ける、コアピンに電磁誘導加熱を設ける、コアピンが固定されているプレートに温度調節回路を設け、媒体による温度管理を行う、温度調節回路をコアピンの外周に設ける、コアピン内部に温度調節回路を設ける(例えば、図3における15)などが挙げられる。 Furthermore, a means for heating the core pin can be provided in the mold to suppress a decrease in the temperature of the core pin. As a method of providing the heating means, a heater is provided inside and / or outside of the core pin, electromagnetic induction heating is provided on the core pin, a temperature control circuit is provided on the plate on which the core pin is fixed, and temperature control is performed by a medium. For example, an adjustment circuit is provided on the outer periphery of the core pin, and a temperature adjustment circuit is provided inside the core pin (for example, 15 in FIG. 3).

本発明の金型は、固定側金型および可動側金型の少なくとも一方がコアピンを有するが、金型の作製が容易である(金型作製のコストが低く、金型の機構を簡略化できる)点から、固定側金型および可動側金型のいずれか一方がコアピンを有するのが好ましく、可動側金型がコアピンを有するのが更に好ましい。 In the mold of the present invention, at least one of the fixed-side mold and the movable-side mold has a core pin, but the mold can be easily manufactured (the cost of mold manufacture is low, and the mold mechanism can be simplified). ) From this point, it is preferable that one of the fixed side mold and the movable side mold has a core pin, and it is more preferable that the movable side mold has a core pin.

本発明の金型は、熱可塑性樹脂の成形に有用であり、金型温度を150℃以上、好ましくは170℃以上、さらに好ましくは190℃以上にする場合に特に有用である。 The mold of the present invention is useful for molding a thermoplastic resin, and is particularly useful when the mold temperature is 150 ° C. or higher, preferably 170 ° C. or higher, more preferably 190 ° C. or higher.

また、本発明の金型は、熱可塑性樹脂の中でも特に非晶性樹脂の成形に有用であり、好ましくはガラス転移温度が160℃以上、より好ましくは180℃以上、さらに好ましくは200℃以上である非晶性樹脂の成形に有用である。 The mold of the present invention is particularly useful for molding amorphous resins among thermoplastic resins, and preferably has a glass transition temperature of 160 ° C. or higher, more preferably 180 ° C. or higher, more preferably 200 ° C. or higher. This is useful for molding certain amorphous resins.

上記非晶性樹脂としては、例えば、ポリエーテルイミド、非晶性ポリイミド、ポリエーテルサルホン、ポリサルホン、ポリアリレート、ポリアミドイミド、ポリフェニレンエーテルなどが挙げられる。 Examples of the amorphous resin include polyetherimide, amorphous polyimide, polyethersulfone, polysulfone, polyarylate, polyamideimide, polyphenylene ether, and the like.

さらに、本発明の金型は、フィラーを20重量%以上、好ましくは30重量%以上、より好ましくは40重量%以上含む熱可塑性樹脂(特に非晶性樹脂)の成形に有用である。フィラーの量の上限は好ましくは80重量%である。フィラーとしては、ガラスファイバー、ガラスフレーク、ガラスビーズ、カーボンファイバー(カーボンウィスカー、カーボンナノチューブを含む)、タルク、マイカ、クレー、ウオラストナイト、無機ウィスカー類(チタン酸カリウムウィスカー、炭化珪素ウィスカー、酸化亜鉛ウィスカー、ホウ酸アルミウィスカー、ウィスカー状炭酸カルシウムなど)が挙げられる。 Furthermore, the mold of the present invention is useful for molding a thermoplastic resin (particularly an amorphous resin) containing 20% by weight or more, preferably 30% by weight or more, more preferably 40% by weight or more of a filler. The upper limit of the amount of filler is preferably 80% by weight. Fillers include glass fibers, glass flakes, glass beads, carbon fibers (including carbon whiskers and carbon nanotubes), talc, mica, clay, wollastonite, inorganic whiskers (potassium titanate whiskers, silicon carbide whiskers, zinc oxide) Whisker, aluminum borate whisker, whisker-like calcium carbonate, etc.).

また、本発明において成形樹脂として使用され得る熱可塑性樹脂は、−30℃〜+30℃の範囲の線膨張係数(TMA法)が5×10−5以下、更には4×10−5以下、特に3×10−5以下であることが好ましく、また、曲げ弾性率(ASTM D790)が3500MPa以上、更には5000MPa以上、特に8000MPa以上であることが好ましい。 The thermoplastic resin that can be used as a molding resin in the present invention has a linear expansion coefficient (TMA method) in the range of −30 ° C. to + 30 ° C. of 5 × 10 −5 or less, more preferably 4 × 10 −5 or less, particularly It is preferably 3 × 10 −5 or less, and the flexural modulus (ASTM D790) is preferably 3500 MPa or more, more preferably 5000 MPa or more, and particularly preferably 8000 MPa or more.

本発明の金型は、コアピンからの放熱を抑えることができるので、成形樹脂としてフィラー入り樹脂を使用しても、成形品の内面でのフィラーの浮き上がりを生じることなく、円筒状成形品を良好な寸法精度で得ることができる。特に、スピンドルモーターのスリーブ等の高い寸法精度を要求される円筒形状の部品の製造に好適に使用できる。また、コアピン全長を従来よりも短くすることにより、コアピンの加工精度の向上および金型組立て時のコアピンの垂直性の向上、およびそれらの結果としての、金型メンテナンスコストの低減および金型寿命の長期化、ならびにコアピンの加工コストの低減という効果も有する。 Since the mold of the present invention can suppress heat dissipation from the core pin, even if a resin containing a filler is used as a molding resin, the cylindrical molded product is excellent without causing the filler to rise on the inner surface of the molded product. Can be obtained with high dimensional accuracy. In particular, it can be suitably used for the manufacture of cylindrical parts that require high dimensional accuracy, such as spindle motor sleeves. In addition, by shortening the overall length of the core pin, the core pin processing accuracy is improved and the verticality of the core pin when assembling the die is improved. It also has the effect of prolonging the length and reducing the core pin processing cost.

本発明に従う金型の一態様を示す概略断面図である。It is a schematic sectional drawing which shows the one aspect | mode of the metal mold | die according to this invention. 円筒状成形品用の従来の金型の概略断面図である。It is a schematic sectional drawing of the conventional metal mold | die for cylindrical molded articles. 本発明に従う金型の別の態様を示す概略断面図である。It is a schematic sectional drawing which shows another aspect of the metal mold | die according to this invention. 本発明に従う金型の別の態様を示す部分断面図である。It is a fragmentary sectional view which shows another aspect of the metal mold | die according to this invention. 本発明に従う金型の別の態様を示す部分断面図である。It is a fragmentary sectional view which shows another aspect of the metal mold | die according to this invention.

符号の説明Explanation of symbols

1 成形品
2 コアピン
3 成形品の胴部外面を形成する雌型
4 固定側金型
4’固定側金型
5 プレート
6 エジェクタースリーブ
7 プレート
8 プレート
9 スプリング
10 プレート
11 プレート
12 成形機エジェクターロッド
13 可動側プラテン
14 温度調節回路用パイプ
15 温度調節回路
16 断熱溝
17 連結用ネジ
18 断熱層
PL パーティングライン
L コアピン全長
T 可動側金型の厚み
DESCRIPTION OF SYMBOLS 1 Molded product 2 Core pin 3 Female type | mold 4 which forms the trunk | drum outer surface of a molded product 4 Fixed side die 4 'Fixed side die 5 Plate 6 Ejector sleeve 7 Plate 8 Plate 9 Spring 10 Plate 11 Plate 12 Molding machine ejector rod 13 Movable Side platen 14 Temperature adjustment circuit pipe 15 Temperature adjustment circuit 16 Heat insulation groove 17 Connection screw 18 Heat insulation layer PL Parting line L Core pin total length T Thickness of movable side mold

Claims (6)

円筒状成形品の射出成形用金型において、固定側金型および可動側金型を有し、固定側金型および可動側金型の少なくとも一方が、成形品の内面を形成するコアピンを有し、コアピンの全長が、上記コアピンを有する側の金型の厚みの10〜80%であることを特徴とする金型。 An injection mold for a cylindrical molded product has a fixed mold and a movable mold, and at least one of the fixed mold and the movable mold has a core pin that forms the inner surface of the molded product. A mold characterized in that the total length of the core pin is 10 to 80% of the thickness of the mold on the side having the core pin. 円筒状成形品の射出成形用金型において、固定側金型および可動側金型を有し、固定側金型および可動側金型の少なくとも一方が、成形品の内面を形成するコアピンを有し、コアピンを構成する材料が、キャビティを形成する他の部材を構成する材料よりも10〜99%低い熱伝導率を有することを特徴とする金型。 An injection mold for a cylindrical molded product has a fixed mold and a movable mold, and at least one of the fixed mold and the movable mold has a core pin that forms the inner surface of the molded product. The metal mold is characterized in that the material constituting the core pin has a thermal conductivity 10 to 99% lower than that of the material constituting the other member forming the cavity. 円筒状成形品の射出成形用金型において、固定側金型および可動側金型を有し、固定側金型および可動側金型の少なくとも一方が、成形品の内面を形成するコアピンを有し、コアピンが断熱部分を有することを特徴とする金型。 An injection mold for a cylindrical molded article has a fixed mold and a movable mold, and at least one of the fixed mold and the movable mold has a core pin that forms the inner surface of the molded article. A mold characterized in that the core pin has a heat insulating part. コアピンを加熱する手段を有する、請求項1または2記載の金型。 The mold according to claim 1 or 2, further comprising means for heating the core pin. 請求項1〜4のいずれか1項記載の金型を用いる射出成形方法。 The injection molding method using the metal mold | die of any one of Claims 1-4. 請求項5記載の射出成形方法により成形された成形品。
A molded product molded by the injection molding method according to claim 5.
JP2008266321A 2008-10-15 2008-10-15 Mold for injection molding of cylindrical molded product, injection molding method and molded product Expired - Fee Related JP5317053B2 (en)

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