JP4801943B2 - Molding method - Google Patents

Molding method Download PDF

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JP4801943B2
JP4801943B2 JP2005201372A JP2005201372A JP4801943B2 JP 4801943 B2 JP4801943 B2 JP 4801943B2 JP 2005201372 A JP2005201372 A JP 2005201372A JP 2005201372 A JP2005201372 A JP 2005201372A JP 4801943 B2 JP4801943 B2 JP 4801943B2
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mold
molten resin
resin
movable mold
surface side
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JP2007015317A (en
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文人 上羽
淳 小泉
誠 奥平
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Honda Motor Co Ltd
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本発明は、裏面側に凸な厚肉部を有する樹脂製品を成形する方法に関する。   The present invention relates to a method for molding a resin product having a thick portion convex on the back surface side.

この種の樹脂製品は、樹脂の収縮によるヒケが厚肉部の表面側に発生し、外観品質が損なわれるという問題がある。そこで、金型のキャビティ内に充填した溶融樹脂を保圧し、その状態で溶融樹脂を固化することで、樹脂の収縮分を補充し、ヒケの発生を防止する方法が提案されている（特許文献１）。この方法では、溶融樹脂の保圧と同時に、裏面側の型面からキャビティ内に加圧ガスを注入して溶融樹脂を表面側の型面に押し付けている。
特開平１１−１９８１６５号公報 This type of resin product has a problem in that sink marks due to resin shrinkage occur on the surface side of the thick-walled portion and the appearance quality is impaired. Therefore, a method has been proposed in which the molten resin filled in the cavity of the mold is held in pressure, and the molten resin is solidified in that state, thereby replenishing the shrinkage of the resin and preventing the occurrence of sink marks (Patent Literature). 1). In this method, simultaneously with the holding pressure of the molten resin, pressurized gas is injected into the cavity from the mold surface on the back surface side to press the molten resin against the mold surface on the front surface side.
Japanese Patent Laid-Open No. 11-198165

しかし、この方法によると、樹脂保圧による凹みが製品の表面に生じ易いという問題と、樹脂保圧と同時に加圧ガスの注入を行っているため、注入するガス圧を高く設定しなければならず、成形装置のコストアップを招くという問題とがある。   However, according to this method, the dent due to the resin holding pressure is likely to occur on the surface of the product, and since the pressurized gas is injected simultaneously with the resin holding pressure, the gas pressure to be injected must be set high. However, there is a problem that the cost of the molding apparatus is increased.

本発明は、このような事情に鑑み、樹脂保圧による凹みの発生がなく、成形装置のコストダウンを図ることができる成形方法を提供することを目的とする。   In view of such circumstances, an object of the present invention is to provide a molding method capable of reducing the cost of a molding apparatus without generating dents due to resin holding pressure.

上記課題を解決するための本発明は、可動型で形成される裏面側に凸な厚肉部を有する樹脂製品を成形する方法であって、前記可動型と固定型からなる金型のキャビティ内に溶融樹脂を充填する第１の工程と、溶融樹脂を保圧することなく、裏面側の可動型面からキャビティ内に気体を注入して溶融樹脂を裏面側の可動型面から剥離する第２の工程と、溶融樹脂を裏面側の可動型面から剥離した状態で固化する第３の工程とを備え、前記固定型を前記可動型よりも高温にすることを特徴とする。 The present invention for solving the above-mentioned problems is a method for molding a resin product having a convex thick wall portion on the back side formed by a movable mold, wherein the mold is formed in a cavity of a mold composed of the movable mold and the fixed mold . And a second step of peeling the molten resin from the movable mold surface on the back surface by injecting gas into the cavity from the movable mold surface on the back surface side without holding the molten resin. And a third step of solidifying the molten resin in a state where the molten resin is peeled from the movable mold surface on the back side, and the fixed mold is heated to a temperature higher than that of the movable mold .

かかる構成によれば、裏面側の型面からキャビティ内に気体を注入すると、溶融樹脂の裏面側が型面から剥離する一方、表面側は型面に密着しようとするため、表面側から固化が始まる。このため、溶融樹脂が表面側に引き寄せられ、その裏面側にヒケが生じる。時間が経過すると、溶融樹脂の裏面側の固化が始まるが、溶融樹脂の表面側は既に固化しているため、表面側にヒケが発生することはない。   According to this configuration, when gas is injected into the cavity from the mold surface on the back surface side, the back surface side of the molten resin is peeled off from the mold surface, while the surface side tends to adhere to the mold surface, so that solidification starts from the surface side. . For this reason, the molten resin is drawn to the front surface side, and sink marks are generated on the back surface side. When the time elapses, solidification of the back side of the molten resin starts. However, since the surface side of the molten resin is already solidified, no sink marks are generated on the front side.

本発明によれば、樹脂保圧が行われなくなるので、製品の表面に凹みが発生しなくなるとともに、裏面側の型面からキャビティ内に注入する気体の圧力が小さくて済み、成形装置のコストダウンを図ることができる。   According to the present invention, since the resin holding pressure is not performed, dents are not generated on the surface of the product, and the pressure of the gas injected into the cavity from the mold surface on the back side can be reduced, thereby reducing the cost of the molding apparatus. Can be achieved.

以下、本発明の実施形態を添付図面に基づいて詳細に説明する。   Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

まず、図１に示すように固定型１と可動型２の間のキャビティ３内に溶融樹脂４を充填する。可動型２の型面には、厚肉部としてのリブを成形するための凹部５を複数個形成してある。   First, as shown in FIG. 1, a molten resin 4 is filled into a cavity 3 between the fixed mold 1 and the movable mold 2. The mold surface of the movable mold 2 is formed with a plurality of recesses 5 for forming ribs as thick portions.

金型（固定型１と可動型２）の温度は、溶融樹脂４が型面に密着し易くするため、通常の温度（４０〜５０℃）よりも高く設定しておく。つまり、金型の温度としては、使用する樹脂材料の固化温度（結晶性樹脂においては結晶化温度、非結晶樹脂においてはガラス転移温度）の近傍に設定する。   The temperature of the mold (the fixed mold 1 and the movable mold 2) is set higher than the normal temperature (40 to 50 ° C.) so that the molten resin 4 can easily adhere to the mold surface. That is, the mold temperature is set in the vicinity of the solidification temperature of the resin material to be used (the crystallization temperature for a crystalline resin and the glass transition temperature for an amorphous resin).

次いで、溶融樹脂４を保圧することなく、可動型２の型面からキャビティ３内に気体を注入して、溶融樹脂４を可動型２の型面から剥離する（図２参照）。この場合、溶融樹脂４の保圧は行っていないので、気体の注入圧が小さくて済むとともに、溶融樹脂４に保圧の影響を与えることなく、溶融樹脂４を固定型１側に効率的に当接させた状態で固化させることができる。   Next, without holding the molten resin 4, gas is injected into the cavity 3 from the mold surface of the movable mold 2, and the molten resin 4 is peeled from the mold surface of the movable mold 2 (see FIG. 2). In this case, since the holding pressure of the molten resin 4 is not performed, the injection pressure of the gas can be small, and the molten resin 4 can be efficiently moved to the fixed mold 1 side without affecting the holding pressure of the molten resin 4. It can be solidified in the contacted state.

つまり、気体の注入には工場エア等を利用することができ、特別な設備は必要なく、コスト的に安価で済む。なお、気体の注入は溶融樹脂４の充填完了の直後に行うのが好ましい。また、気体の注入は所定の時間行われるが、製品の表面にうねりや反りが生じない範囲で連続注入または延長が可能になる。   In other words, factory air or the like can be used for gas injection, no special equipment is required, and the cost is low. The gas injection is preferably performed immediately after completion of the filling of the molten resin 4. In addition, although gas is injected for a predetermined time, continuous injection or extension is possible within a range in which no swell or warpage occurs on the surface of the product.

図７は可動型２の気体注入通路の構造を示す図で、リブ成形用の凹部５の間に気体注入通路６を配設してある。この気体注入通路６は、型面への開口部に焼結鋼７を設置し、溶融樹脂４の進入を阻止している。なお、注入した気体は金型内に留めておく必要はなく、金型の合わせ面等から大気中に放出すればよい。つまり、注入気体をシールする必要がなく、コスト的に安価で済む。   FIG. 7 is a view showing the structure of the gas injection passage of the movable mold 2, and the gas injection passage 6 is disposed between the rib forming recesses 5. The gas injection passage 6 is provided with sintered steel 7 at the opening to the mold surface to prevent the molten resin 4 from entering. The injected gas need not be kept in the mold, and may be released into the atmosphere from the mating surface of the mold. That is, there is no need to seal the injected gas, and the cost can be reduced.

ところで、金型の温度は上述のように通常よりも高く設定してあるので、キャビティ３内に充填された溶融樹脂４には、図３に示すように固定型１の型面に密着しようとする力が働く。このため、溶融樹脂４は図４に示すように固定型１の型面に密着し、その表面側から固化が始まる。表面側の固化層４ａの形成にともなって、溶融樹脂４が固定型１側に引き寄せられ、裏面側のヒケｈが進行する。一方、溶融樹脂４の裏面側は気体の注入によって可動型２の型面から剥離し、空気断熱層が形成されているため、表面側よりも冷却の進行が遅れ、固化層の形成はまだ始まっていない。   By the way, since the temperature of the mold is set higher than usual as described above, the molten resin 4 filled in the cavity 3 tries to adhere to the mold surface of the fixed mold 1 as shown in FIG. The power to do works. For this reason, as shown in FIG. 4, the molten resin 4 comes into close contact with the mold surface of the fixed mold 1 and solidification starts from the surface side. With the formation of the solidified layer 4a on the front surface side, the molten resin 4 is attracted to the fixed mold 1 side, and sink marks h on the back surface side advance. On the other hand, since the back surface side of the molten resin 4 is peeled off from the mold surface of the movable mold 2 by gas injection and an air heat insulating layer is formed, the progress of cooling is delayed as compared with the front surface side, and the formation of the solidified layer is still started. Not.

なお、金型（固定型１と可動型２）の温度に関しては、固定型１を可動型２よりある程度高温にすると、溶融樹脂４がエアーアシストを受けて高温の固定型１に製品表面を密着した状態で引っ張られ、製品表面のヒケ発生の防止に効果的である。   In addition, regarding the temperature of the molds (fixed mold 1 and movable mold 2), when the fixed mold 1 is heated to a certain degree higher than the movable mold 2, the molten resin 4 receives air assist to bring the product surface into close contact with the high temperature fixed mold 1 It is effective in preventing the occurrence of sink marks on the product surface.

因みに、可動型２を固定型１より低温にし過ぎると、可動型２の温度の影響で、樹脂の溶融状態が維持されずに早く固化してしまい、固定型１に樹脂が密着しにくくなる。また、可動型２を固定型１より高温にすると、可動型２付近の樹脂が溶融した状態で、エアーアシストを受けても、うまく可動型２から剥離しない。   Incidentally, when the movable mold 2 is set to a temperature lower than that of the fixed mold 1, the molten state of the resin is not maintained and the resin is solidified quickly due to the temperature of the movable mold 2, and the resin is less likely to adhere to the fixed mold 1. Further, when the movable mold 2 is heated to a temperature higher than that of the fixed mold 1, even if the air assist is received in a state where the resin near the movable mold 2 is melted, the movable mold 2 does not peel off from the movable mold 2 well.

時間が経過すると、溶融樹脂４の裏面側にも、図５に示すような固化層４ｂが形成されるが、表面側には既に固化層４ａが形成されているため、裏面側の固化層４ｂの形成にともなうヒケが製品の表面に生じることはない。   When time elapses, a solidified layer 4b as shown in FIG. 5 is also formed on the back surface side of the molten resin 4, but since the solidified layer 4a is already formed on the front surface side, the solidified layer 4b on the back surface side. There is no sink on the surface of the product.

図６はこのようして成形された製品Ｗを示している。製品Ｗの裏面には、平板部ＦからリブＲの周面に跨るヒケｈを生じるが、表面側にはヒケは生じない。   FIG. 6 shows the product W formed in this way. On the back surface of the product W, sink marks h extending from the flat plate portion F to the peripheral surface of the rib R are generated, but no sink marks are generated on the front surface side.

〔実施例〕
以下の条件で成形を行うと、製品表面にヒケが生じないことが確認された。
非結晶樹脂での実験結果
１．金型温度
固定型１の型面温度：８０℃
可動型２の型面温度：７０℃
２．気体の注入圧力：０.４〜０.５Ｍｐａ
３．気体の注入時間：５秒
４．樹脂保圧：なし 〔Example〕
When molding was performed under the following conditions, it was confirmed that there was no sink on the product surface.
Experimental results with amorphous resin Mold temperature Mold surface temperature of fixed mold 1: 80 ℃
Mold surface temperature of movable mold 2: 70 ° C
2. Gas injection pressure: 0.4 to 0.5 Mpa
3. 3. Gas injection time: 5 seconds Resin holding pressure: None

本発明の成形方法の第１工程を示す図。The figure which shows the 1st process of the shaping | molding method of this invention. 本発明の成形方法の第２工程を示す図。The figure which shows the 2nd process of the shaping | molding method of this invention. 本発明の成形方法の第３工程を示す図。The figure which shows the 3rd process of the shaping | molding method of this invention. 本発明の成形方法の第４工程を示す図。The figure which shows the 4th process of the shaping | molding method of this invention. 本発明の成形方法の第５工程を示す図。The figure which shows the 5th process of the shaping | molding method of this invention. 本発明の成形方法による製品を示す図。The figure which shows the product by the shaping | molding method of this invention. 本発明の成形方法の実施に使用する金型の断面図。Sectional drawing of the metal mold | die used for implementation of the shaping | molding method of this invention.

符号の説明Explanation of symbols

１ 固定型
２ 可動型
３ キャビティ
４ 溶融樹脂
５ リブ成形用凹部
６ 気体注入通路
７ 焼結鋼
Ｗ 製品
Ｒ リブ
ｈ ヒケ DESCRIPTION OF SYMBOLS 1 Fixed type 2 Movable type 3 Cavity 4 Molten resin 5 Rib forming recessed part 6 Gas injection path 7 Sintered steel W Product R Rib h Sink

Claims (1)

可動型で形成される裏面側に凸な厚肉部を有する樹脂製品を成形する方法であって、
前記可動型と固定型からなる金型のキャビティ内に溶融樹脂を充填する第１の工程と、
溶融樹脂を保圧することなく、裏面側の可動型面からキャビティ内に気体を注入して溶融樹脂を裏面側の可動型面から剥離する第２の工程と、
溶融樹脂を裏面側の可動型面から剥離した状態で固化する第３の工程と、
を備え、
前記固定型を前記可動型よりも高温にすることを特徴とする成形方法。 A method of molding a resin product having a thick portion convex on the back side formed by a movable mold ,
A first step of filling molten resin into a cavity of a mold composed of the movable mold and the fixed mold ;
A second step of injecting gas into the cavity from the movable mold surface on the back side without peeling the molten resin and peeling the molten resin from the movable mold surface on the back side;
A third step of solidifying the molten resin in a state of being peeled from the movable mold surface on the back side;
With
A molding method characterized in that the fixed mold is heated to a higher temperature than the movable mold .
JP2005201372A 2005-07-11 2005-07-11 Molding method Expired - Fee Related JP4801943B2 (en)

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JP2007015317A JP2007015317A (en) 2007-01-25
JP4801943B2 true JP4801943B2 (en) 2011-10-26

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Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3790317B2 (en) * 1997-02-17 2006-06-28 旭化成ケミカルズ株式会社 Gas combined injection molding method
JP4303844B2 (en) * 1999-09-22 2009-07-29 株式会社プライムポリマー Method for producing fiber-containing lightweight resin tray
JP2002316347A (en) * 2001-02-13 2002-10-29 Sanraito Kasei Kk Mold assembly and injection molding method

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