JPH0724867A - Multiple injection molding of plastic - Google Patents
Multiple injection molding of plasticInfo
- Publication number
- JPH0724867A JPH0724867A JP20582293A JP20582293A JPH0724867A JP H0724867 A JPH0724867 A JP H0724867A JP 20582293 A JP20582293 A JP 20582293A JP 20582293 A JP20582293 A JP 20582293A JP H0724867 A JPH0724867 A JP H0724867A
- Authority
- JP
- Japan
- Prior art keywords
- cavity
- molten resin
- volume
- injection
- filling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、プラスチックの多重射
出成形方法に係わり、特に部分的に厚肉部を有するプラ
スチック成形品に発生し易いヒケを防止し、成形品の外
観を良好にする、射出成形や射出圧縮成形などの成形方
法に好適なプラスチックの多重射出成形方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for multiple injection molding of plastics, and particularly, prevents sink marks that are likely to occur in a plastic molded product having a partially thick portion, and improves the appearance of the molded product. The present invention relates to a multiple injection molding method for plastics suitable for molding methods such as injection molding and injection compression molding.
【０００２】[0002]
【従来の技術】従来、電気製品や自動車の外装部品など
に使用されているプラスチック成形品を成形する場合
は、射出成形や射出圧縮成形等が採用されているが、肉
厚の変化が大きい部分にはヒケが生じて商品価値を大き
く低下させるため、次のようなヒケを少なくする成形方
法および製品が知られている。 （１）肉厚の急激な変化を避ける目的で、肉厚変化をな
だらかにさせたり、ボスやリブの取り付け部近傍の母体
側の厚さを厚くする等の製品設計。 （２）全体あるいはヒケの発生する部分に窒素などのガ
スを注入して厚肉部の樹脂部分を少なくする、あるいは
薄くするガスインジェクション。2. Description of the Related Art Conventionally, injection molding, injection compression molding, etc. have been adopted for molding plastic moldings used for electric products and exterior parts of automobiles. Since sink marks are generated and the commercial value is greatly reduced, the following molding methods and products for reducing sink marks are known. (1) In order to avoid sudden changes in wall thickness, product design such as smoothing the wall thickness change and increasing the thickness of the base side near the attachment parts of bosses and ribs. (2) Gas injection for injecting a gas such as nitrogen into the whole or a portion where a sink mark occurs to reduce or thin the resin portion of the thick portion.
【０００３】（３）まず外装樹脂を定められ量だけ金型
のキャビティ内に射出し、次に芯部樹脂として発泡して
いる樹脂を射出する。発泡樹脂は未発泡樹脂のコア層と
して押し込まれる。最後に未発泡樹脂を射出し、ノズル
周辺をシ−ルする二重射出成形方法（低発泡成形Ｃｏ−
ｉｎｊｅｃｔｉｏｎ成形技術：合成樹脂、１９８６年７
月号、ｐ．２〜６）。 （４）発泡コア層と未発泡スキン層とを１回で成形する
発泡成形方法。 （５）射出成形方法により、リブなどの厚肉部を有する
部品を成形する場合、リブなど部品の内面側を成形後、
（イ）部品を取り出し別の射出成形機で最終用の型にイ
ンサ−トして成形したり、（ロ）該１回目の射出品を装
着したままの型を回転させ、別の最終用の型と構成され
るキャビティに２度目の射出を行ったり、して二重成形
し、１回目に生じるヒケを埋める（例えば、実開平２−
１０９８号公報）。(3) First, a predetermined amount of exterior resin is injected into the cavity of the mold, and then foamed resin is injected as the core resin. The foamed resin is pressed as a core layer of unfoamed resin. Finally, a non-foaming resin is injected and the nozzle periphery is sealed.
injection molding technology: synthetic resin, 1986 7
Monthly issue, p. 2-6). (4) A foam molding method in which the foam core layer and the unfoamed skin layer are molded once. (5) When molding a component having a thick portion such as a rib by an injection molding method, after molding the inner surface side of the component such as the rib,
(A) Take out the parts and insert into a final mold with another injection molding machine for molding, or (b) rotate the mold with the first-time injection product still attached, and use it for another final mold. The cavity formed by the mold is injected a second time and then double-molded to fill the sink mark generated the first time (eg
1098 publication).
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、上記従
来の成形方法および製品には次のような問題点がある。 （１）に記載された設計では、製品の肉厚変化をなだら
かにするために厚肉部分が増加し製品重量が重くなり、
プラスチック材料費の増加、環境問題の増長等の問題が
ある。製品重量を軽くすることは、省資源、自動車にお
ける排気ガス量低減・燃費低減、電気製品での運搬の容
易性等から重要である。また、製品重量が増大すると、
場合によっては成形機械の射出容量の大きい機械が必要
となり、大型のため型作動が遅くなることによる生産効
率の低下、償却費の増加になり、生産コストが高くな
る。However, the above-mentioned conventional molding method and product have the following problems. In the design described in (1), in order to smooth the change in the product thickness, the thick part increases and the product weight becomes heavy.
There are problems such as an increase in plastic material costs and an increase in environmental problems. Reducing the product weight is important from the viewpoint of resource saving, reduction of exhaust gas amount and fuel consumption in automobiles, and ease of transportation by electric products. Also, as the product weight increases,
In some cases, a molding machine with a large injection capacity is required, and the large size of the machine slows down the mold operation, resulting in a decrease in production efficiency, an increase in depreciation costs, and an increase in production costs.
【０００５】（２）に記載されたガスインジェクション
では、内部にガスにより空間を形成している個所の製
品の表面部分にはムラ、特に色ムラを生じ易く、商品価
値を低下させために、必要に応じて更に表面塗装を行っ
たり、ガスチャンネルを形成するために製品設計が制
限されることがある。また、ガスの圧力は一般的にお
およそ２００ｋｇ／ｃｍ2 と高圧であり、作業には危険
が伴い易く、ガス関連の装置も高価である。 （３）に記載された二重射出成形方法（２台の射出装置
で二重に射出する）では、溶融樹脂の内部を発泡樹脂が
流れなければならないために、製品の肉厚も厚くする必
要がある。また、多材質成形品あるいは多色成形品のよ
うに、１回目の射出と２回目以後の射出される材料ある
いは色が異なる樹脂を射出する例もあるが、これは一度
成形した製品の金型を開き、そのキャビティより大きい
キャビティと組み合わされてその空間に次の射出を行う
ので、１回の成形サイクルの２倍以上の成形時間が必要
となり、生産性に問題がある。In the gas injection described in (2), unevenness, especially color unevenness is apt to occur on the surface portion of the product where the space is formed by the gas inside, and it is necessary to reduce the commercial value. Depending on the application, the product design may be limited due to further surface coating and forming gas channels. In addition, the gas pressure is generally high at about 200 kg / cm 2 , and the work is likely to be dangerous, and the gas-related device is expensive. In the double injection molding method described in (3) (double injection with two injection devices), since the foamed resin must flow inside the molten resin, it is necessary to increase the product thickness. There is. There is also an example of injecting material or resin of different colors that is injected after the first injection and after the second injection, such as a multi-material molded product or a multi-color molded product. Is opened and the next injection is performed in the space in combination with a cavity larger than that cavity, which requires a molding time that is at least twice as long as one molding cycle, resulting in a problem in productivity.
【０００６】（４）に記載された発泡成形方法は、肉の
厚いボスやリブ等の内部に安定して一定の発泡層を形成
することが困難である。その理由として、表面のヒケが
出ないようにするには、スキン層の厚さは内部発泡層の
圧力に充分耐え得る厚さである必要がある。発泡圧力に
耐え得る厚さが無い場合には、発泡ガスの発生する圧力
によって、その部分にフクレ（ヒケとは反対方向の変
形）が生じる。逆にスキン層が厚くなり過ぎると、内部
発泡ガスによるヒケ防止よりもスキン層厚さ部の樹脂収
縮により、表面にヒケが生じる。したがって、発泡層の
発生ガス量の違いとスキン層の厚さとの関係によってフ
クレかヒケが発生するため、スキン層厚さを適切に制御
できなければ、ヒケのない一定した成形品を製造するこ
とは困難である。しかし、スキン層の厚さは制御が困難
な金型の温度変化により変動し、発泡層のガス発生量は
化学発泡材自体の均一性や可塑化装置（内部にスクリュ
−があるシリンダ部）の混練性、溶融樹脂温度の均一性
等の多くの要因により変化するので、それら全てを制御
管理することは困難である。In the foam molding method described in (4), it is difficult to stably form a uniform foam layer inside thick bosses or ribs. The reason is that the thickness of the skin layer must be sufficient to withstand the pressure of the internal foam layer in order to prevent the occurrence of sink marks on the surface. If there is not enough thickness to withstand the foaming pressure, the pressure generated by the foaming gas causes blisters (deformation in the direction opposite to the sink marks) at that portion. On the contrary, when the skin layer becomes too thick, sink marks are generated on the surface due to resin shrinkage in the skin layer thickness portion rather than sink mark prevention by internal foaming gas. Therefore, since blistering or sinking occurs due to the relationship between the difference in the amount of gas generated in the foam layer and the thickness of the skin layer, if the skin layer thickness cannot be controlled appropriately, it is necessary to manufacture a molded product with no sink mark. It is difficult. However, the thickness of the skin layer fluctuates due to the temperature change of the mold, which is difficult to control, and the gas generation amount of the foam layer depends on the uniformity of the chemical foam material itself and the plasticizer (cylinder part having the screw inside). Since it depends on many factors such as kneading property and uniformity of molten resin temperature, it is difficult to control and manage all of them.
【０００７】（５）に記載された射出成形による二重成
形において、射出装置（射出シリンダ、ノズルを含む）
あるいは金型のうち少なくともどちらかは複数使用する
か、射出シリンダあるいはノズルを複数有する射出装置
が必要である。これら射出装置および金型はともに高価
であり、それぞれ１台および１式にできれば、コストの
低減、即ち産業への貢献となる。In double molding by injection molding described in (5), an injection device (including an injection cylinder and a nozzle)
Alternatively, a plurality of at least one of the molds is used, or an injection device having a plurality of injection cylinders or nozzles is required. Both the injection device and the mold are expensive, and if one unit and one set are provided, the cost can be reduced, that is, it can contribute to the industry.
【０００８】本発明は、上記従来技術の問題点に着目
し、部分的にボスやリブ等の肉の厚い部分を有するプラ
スチック成形品に発生しやすいヒケを防止し、成形品の
外観を良好にし、さらに高いコスト、環境問題、不安定
な製造などを解決できる、プラスチックの多重射出成形
方法を提供することを目的とする。The present invention focuses on the above-mentioned problems of the prior art to prevent sink marks which are likely to occur in a plastic molded product partially having thick parts such as bosses and ribs, and to improve the appearance of the molded product. Another object of the present invention is to provide a plastic multiple injection molding method capable of solving higher costs, environmental problems, unstable manufacturing, and the like.
【０００９】[0009]
【課題を解決するための手段】上記目的を達成するため
に、本発明に係わるプラスチックの多重射出成形方法に
おける第１発明は、部分的にリブあるいはボスなどの厚
肉部を有するプラスチック成形品の成形方法において、
（イ）最終成形品容積より小さい所定のキャビティ容積
を設定し、そのキャビティに第１回目の溶融樹脂の射出
充填を行い、（ロ）その後に、最終成形品容積となる第
２回目の溶融樹脂の射出充填を行う、工程から成ること
を特徴とする。In order to achieve the above object, the first invention in the method for multiple injection molding of plastics according to the present invention is a plastic molded article having a thick portion such as a rib or a boss partially. In the molding method,
(A) A predetermined cavity volume smaller than the volume of the final molded product is set, and the cavity is injected and filled with the molten resin for the first time, and (b) after that, the molten resin for the second time becomes the volume of the final molded product. Injection filling is performed.
【００１０】第２発明は、第１発明において、第１回目
の射出充填工程として、所定のキャビティ容積より、予
め縮小したキャビティに溶融樹脂を射出充填しながら、
第１回目の所定のキャビティ容積まで拡大を行う。第３
発明は、第１発明において、第１回目の射出充填工程と
して、所定のキャビティ容積より、予め拡大したキャビ
ティに溶融樹脂射出を行った後、あるいは行いながら、
第１回目の所定のキャビティ容積まで縮小し充填する。
第４発明は、第１発明乃至第３発明において、第１回目
の射出充填後、キャビティを最終成形品容積まで拡大
し、その拡大したキャビティに第２回目の溶融樹脂射出
充填を行う。第５発明は、第１発明乃至第３発明におい
て、第１回目の射出充填後、キャビティを最終成形品容
積以下に拡大し、その拡大したキャビティに第２回目の
溶融樹脂を射出充填しながら、最終成形品容積まで拡大
を行う。第６発明は、第１発明乃至第３発明において、
第１回目の射出充填後、キャビティを最終成形品容積以
上に拡大し、その拡大したキャビティに第２回目の溶融
樹脂射出を行った後、あるいは、行いながら最終成形品
容積まで縮小し充填する。In a second aspect of the present invention, in the first aspect of the present invention, as a first injection filling step, while a molten resin is injected and filled into a cavity which is previously reduced from a predetermined cavity volume,
The first cavity is expanded to a predetermined cavity volume. Third
According to the first aspect of the invention, in the first aspect, as the first injection filling step, after or while performing the molten resin injection into the cavity that has been expanded in advance from the predetermined cavity volume,
The volume of the first cavity is reduced to a predetermined volume and filled.
In the fourth invention, in the first to third inventions, after the first injection filling, the cavity is expanded to the volume of the final molded product, and the expanded cavity is subjected to the second molten resin injection filling. In a fifth invention, in the first invention to the third invention, after the first injection filling, the cavity is expanded to a volume of the final molded product or less, and the expanded cavity is injected and filled with the second molten resin, Expand to the volume of the final molded product. A sixth invention is the same as the first invention to the third invention,
After the first injection filling, the cavity is expanded to a volume of the final molded product or more, and the expanded cavity is injected with the molten resin for the second time, or while the cavity is expanded, the volume of the final molded product is reduced and filled.
【００１１】第７発明は、第１発明乃至第６発明におい
て、第１回目の溶融樹脂が射出された成形品は発泡した
状態であり、第２回目の溶融樹脂が射出された成形品部
は発泡していない状態である。第８発明は、第１発明乃
至第７発明において、第１回目と第２回目に射出された
溶融樹脂は同一の材料である。第９発明は、第１発明乃
至第８発明において、第１回目の射出充填および第２回
目の射出充填を、同一の射出装置および金型により行
う。According to a seventh aspect of the invention, in the first to sixth aspects of the invention, the molded product injected with the first molten resin is in a foamed state, and the molded product part injected with the second molten resin is It is in a state of not foaming. In an eighth invention, in the first invention to the seventh invention, the molten resin injected in the first time and the molten resin injected in the second time are the same material. In the ninth invention, in the first invention to the eighth invention, the first injection filling and the second injection filling are performed by the same injection device and mold.
【００１２】第１０発明は、部分的にリブあるいはボス
などの厚肉部を有するプラスチック成形品の成形方法に
おいて、（イ）キャビティを第１回目の所定キャビティ
容積に設定し、溶融樹脂を射出充填する第１工程、
（ロ）キャビティを第２回目の所定キャビティ容積まで
拡大し、溶融樹脂を射出充填する第２工程、（ハ）キャ
ビティを第３回目の所定キャビティ容積まで拡大し、溶
融樹脂を射出充填する第３工程、以上の工程からなるこ
とを特徴とする。A tenth aspect of the present invention is a method for molding a plastic molded product having a thick portion such as a rib or a boss partially. (A) The cavity is set to a predetermined cavity volume for the first time, and a molten resin is injected and filled. The first step to do,
(B) A second step of expanding the cavity to the predetermined cavity volume of the second time and injecting and filling the molten resin, and (c) a third step of expanding the cavity to the predetermined cavity volume of the third time and injecting and filling the molten resin. The process is characterized by comprising the above steps.
【００１３】第１１発明は、第１０発明において、
（イ）は、キャビティを第１回目の所定キャビティ容積
より縮小し、溶融樹脂を射出充填しながら第１回目の所
定キャビティ容積まで拡大する第１工程、である。第１
２発明は、第１０発明において、（イ）は、キャビティ
を第１回目の所定キャビティ容積より拡大し、溶融樹脂
を射出した後、あるいは溶融樹脂を射出しながら、第１
回目の所定キャビティ容積まで縮小し充填する第１工
程、である。第１３発明は、第１０発明乃至第１２発明
において、（ロ）は、キャビティを第２回目の所定キャ
ビティ容積より縮小し、溶融樹脂を射出充填しながら第
２回目の所定キャビティ容積まで拡大する第２工程、で
ある。第１４発明は、第１０発明乃至第１２発明におい
て、（ロ）は、キャビティを第２回目の所定キャビティ
容積より拡大し、溶融樹脂を射出した後、あるいは溶融
樹脂を射出しながら、第２回目の所定キャビティ容積ま
で縮小し充填する第２工程、である。An eleventh invention is the tenth invention,
(A) is a first step in which the cavity is reduced from the first-time predetermined cavity volume and expanded to the first-time predetermined cavity volume while injecting and filling the molten resin. First
2nd invention is, in the 10th invention, in (a), the cavity is expanded from the predetermined cavity volume of the first time, and after the molten resin is injected or while the molten resin is being injected,
The first step is to reduce the volume of the cavity to a predetermined cavity volume and fill the cavity. A thirteenth invention is, in the tenth invention to the twelfth invention, in (b), the cavity is reduced from a predetermined cavity volume of the second time and expanded to the second cavity volume of the second time while injecting and filling the molten resin. Two steps. A fourteenth invention is the tenth invention to the twelfth invention, wherein (B) is the second time after the cavity is expanded from a predetermined cavity volume of the second time and the molten resin is injected or while the molten resin is being injected. The second step of reducing the volume of the cavity to a predetermined cavity volume and filling the cavity.
【００１４】第１５発明は、第１０発明乃至第１４発明
において、（ハ）は、キャビティを第３回目の所定キャ
ビティ容積より縮小し、溶融樹脂を射出充填しながら第
３回目の所定キャビティ容積まで拡大する第３工程、で
ある。第１６発明は、第１０発明乃至第１４発明におい
て、（ハ）は、キャビティを第３回目の所定キャビティ
容積より拡大し、溶融樹脂を射出した後、あるいは溶融
樹脂を射出しながら、第３回目の所定キャビティ容積ま
で縮小し充填する第３工程、である。第１７発明は、第
１０発明乃至第１６発明において、（イ）〜（ハ）の３
工程を、同一の射出装置および金型により行う。第１８
発明は、第１０発明乃至第１７発明において、（ニ）キ
ャビティを所定キャビティ容積まで拡大し、溶融樹脂を
射出充填する工程、（ホ）キャビティを所定キャビティ
容積より縮小し、溶融樹脂を射出充填しながら所定キャ
ビティ容積まで拡大する工程、（ヘ）キャビティを所定
キャビティ容積より拡大し、溶融樹脂を射出した後、あ
るいは溶融樹脂を射出しながら、所定キャビティ容積ま
で縮小し充填する工程、の３工程において、（ハ）の第
３工程後、さらに、（ニ）〜（へ）のいずれか１工程を
少なくとも１回行う。本発明に係わるプラスチックの多
重射出成形方法は以上の構成とした。A fifteenth aspect of the invention is the tenth to fourteenth aspects, wherein (c) reduces the cavity from a predetermined cavity volume of the third time and injection-fills the molten resin up to the predetermined cavity volume of the third time. This is the third step of enlarging. A sixteenth invention is the tenth invention to the fourteenth invention, wherein (c) is the third time after the cavity is expanded from a predetermined cavity volume of the third time and the molten resin is injected or while the molten resin is injected. The third step of reducing the volume of the cavity to a predetermined cavity volume and filling the cavity. A seventeenth invention is the invention of the tenth to sixteenth inventions, in which (a) to (c)
The process is performed with the same injection device and mold. 18th
According to the invention, in the tenth invention to the seventeenth invention, (d) a step of expanding the cavity to a predetermined cavity volume and injecting and filling the molten resin, (e) reducing the cavity to a predetermined cavity volume, and injecting and filling the molten resin. While expanding the cavity volume to a predetermined cavity volume while (f) expanding the cavity from the predetermined cavity volume and injecting the molten resin, or while injecting the molten resin, reducing and filling the cavity volume to the predetermined cavity volume. After the third step of (c), any one step of (d) to (e) is further performed at least once. The plastic multiple injection molding method according to the present invention has the above-described structure.
【００１５】[0015]
【作用】本発明は、プラスチックの多重射出成形方法に
係わるが、説明の便宜上、第１回目と第２回目との射出
工程からなる場合を二重射出成形あるいは二重射出成形
方法、第１回目〜第３回目の射出工程からなる場合を三
重射出成形あるいは三重射出成形方法、第３回目の射出
工程後さらに少なくとも１回以上の射出工程からなる場
合を四重射出成形あるいは四重射出成形方法、と言う。The present invention relates to a multiple injection molding method for plastics, but for convenience of explanation, the case of the first and second injection steps is the double injection molding or the double injection molding method, the first injection molding method. A triple injection molding or a triple injection molding method in the case of the third injection step, a quadruple injection molding method or a quadruple injection molding method in the case of at least one injection step after the third injection step, Say
【００１６】通常の成形において、部分的にボスやリブ
などの厚肉部分がある成形品では、成形品の冷却に伴う
収縮により、厚肉部にヒケが生じる。ここで、図１３に
示す金型の成形品キャビティ１００の寸法に基づき、通
常の成形である１回成形でのヒケ量を求める。図１３を
補足すると、底面肉厚Ａの部分に、高さＢのボス１００
ａと高さＣのリブ１００ｂが付いた形状である。射出直
後の溶融樹脂温度ＴＲとキャビティから取り出し後の最
終製品温度ＴＥとの温度差を△Ｔ１（＝ＴＲ−ＴＥ）と
すれば、各部の収縮量は次式となり、各部の収縮量は異
なる。 底面部収縮量△ＳG1＝α・△Ｔ１・Ａ ボス部収縮量△ＳB1＝α・△Ｔ１・（Ｂ＋Ａ） リブ部収縮量△ＳR1＝α・△Ｔ１・（Ｃ＋Ａ） 但し、α：使用する材料の熱収縮率 したがって、ボス部、リブ部の収縮量と底面部収縮量と
の差により生じるヒケ量は次式となり、この通常の１回
成形でのヒケ１０１を模式的に図１４に示す。 ボス部ヒケ量△ＭB1＝α・△Ｔ１・Ｂ ・・・・・・・・・（１） リブ部ヒケ量△ＭR1＝α・△Ｔ１・Ｃ ・・・・・・・・・（２） このヒケ量をガスインジェクションや発泡成形では、ガ
スや発泡ガスで補っている。In a usual molding, in a molded product having a thick portion such as a boss or a rib, a shrinkage occurs in the thick portion due to shrinkage accompanying cooling of the molded product. Here, based on the dimensions of the molded product cavity 100 of the mold shown in FIG. 13, the amount of sink mark in the normal molding, which is one-time molding, is obtained. Complementing FIG. 13, a boss 100 having a height B is formed at the bottom wall thickness A portion.
It has a shape with a and a rib 100b of height C. Assuming that the temperature difference between the molten resin temperature TR immediately after injection and the final product temperature TE after taking out from the cavity is ΔT1 (= TR-TE), the shrinkage amount of each part is given by the following equation, and the shrinkage amount of each part is different. Bottom part shrinkage ΔS G1 = α ・ ΔT1 ・ A Boss shrinkage ΔS B1 = α ・ ΔT1 ・ (B + A) Rib part shrinkage ΔS R1 = α ・ △ T1 ・ (C + A) where α: Therefore, the shrinkage amount caused by the difference between the shrinkage amount of the boss portion and the rib portion and the shrinkage amount of the bottom surface portion is given by the following equation. Shown in. Boss sink amount ΔM B1 = α ・ ΔT1 ・ B ・ ・ ・ ・ ・ ・ (1) Rib sink amount ΔM R1 = α ・ ΔT1 ・ C ・ ・ ・ ・ ・ ・ ( 2) This amount of sink mark is supplemented with gas or foaming gas in gas injection or foam molding.
【００１７】本発明の二重射出成形では、第１回目の成
形時には通常の成形におけるキャビティ（図１３の形
状）の底面肉厚ＡよりＸ薄い状態に成形し、その後残り
の部分に第２回目の溶融樹脂を射出充填するものであ
る。第１回目射出の所定キャビティを図１５に示す。射
出充填後、この成形品がキャビティ内で温度ＴＣまで冷
却すると、各部分の収縮量は次式となり、図１６に第１
回目射出充填後の温度ＴＣにおける収縮状態を模式的に
示す。 底面部収縮量△ＳG2＝α・△Ｔ２・（Ａ−Ｘ） ボス部収縮量△ＳB2＝α・△Ｔ２・（Ａ＋Ｂ−Ｘ） リブ部収縮量△ＳR2＝α・△Ｔ２・（Ａ＋Ｃ−Ｘ） 但し、△Ｔ２＝ＴＲ−ＴＣIn the double injection molding of the present invention, at the time of the first molding, the cavity is molded to a thickness X thinner than the bottom wall thickness A of the cavity (shape of FIG. 13) in the normal molding, and then the second portion is molded in the remaining portion. The molten resin of (1) is injected and filled. The predetermined cavity for the first injection is shown in FIG. After injection filling, when this molded product is cooled to the temperature TC in the cavity, the shrinkage amount of each part becomes the following formula, and the first formula in FIG.
The contraction state at the temperature TC after the second injection filling is schematically shown. Bottom part shrinkage ΔS G2 = α ・ ΔT2 ・ (A−X) Boss shrinkage ΔS B2 = α ・ ΔT2 ・ (A + B−X) Rib part shrinkage ΔS R2 = α ・ ΔT2 ・ ( A + C−X) However, ΔT2 = TR−TC
【００１８】さらに、第２回目のキャビティ部分に温度
ＴＲの溶融樹脂を射出充填するが、この時追加射出部分
１１０（図１７）の厚さは次式となる。 底面部厚さＤG1＝α・△Ｔ２・（Ａ−Ｘ）＋Ｘ ボス部厚さＤB1＝α・△Ｔ２・（Ａ＋Ｂ−Ｘ）＋Ｘ リブ部厚さＤR1＝α・△Ｔ２・（Ａ＋Ｃ−Ｘ）＋Ｘ これらの追加射出部分が最終製品温度ＴＥまで冷却され
ると、各部分の収縮量は次式となる。 底面部収縮量△ＳG3＝α・△Ｔ１・｛α・△Ｔ２・（Ａ
−Ｘ）＋Ｘ｝ ボス部収縮量△ＳB3＝α・△Ｔ１・｛α・△Ｔ２・（Ａ
＋Ｂ−Ｘ）＋Ｘ｝ リブ部収縮量△ＳR3＝α・△Ｔ１・｛α・△Ｔ２・（Ａ
＋Ｃ−Ｘ）＋Ｘ｝ したがって、ボス部、リブ部のヒケ量は次式になる。 ボス部ヒケ量△ＭB3＝α2 ・△Ｔ１・△Ｔ２・Ｂ ・・・・・・・（３） リブ部ヒケ量△ＭR3＝α2 ・△Ｔ１・△Ｔ２・Ｃ ・・・・・・・（４）Further, the molten resin at the temperature TR is injected and filled in the second cavity portion, and the thickness of the additional injection portion 110 (FIG. 17) at this time is given by the following equation. Bottom thickness D G1 = α ・ ΔT2 ・ (AX) + X Boss thickness D B1 = α ・ ΔT2 ・ (A + B−X) + X Rib thickness D R1 = α ・ ΔT2 ・ (A + C -X) + X When these additional injection parts are cooled to the final product temperature TE, the shrinkage amount of each part is given by the following equation. Bottom shrinkage ΔS G3 = α ・ ΔT1 ・ {α ・ ΔT2 ・ (A
-X) + X} Boss shrinkage ΔS B3 = α ・ ΔT1 ・ {α ・ ΔT2 ・ (A
+ B−X) + X} Rib shrinkage ΔS R3 = α ・ ΔT1 ・ {α ・ ΔT2 ・ (A
+ C−X) + X} Therefore, the sink amount of the boss portion and the rib portion is given by the following equation. Boss sink amount ΔM B3 = α 2 · ΔT 1 · ΔT 2 · B ··· (3) Rib sink amount ΔM R 3 = α 2 · ΔT 1 / ΔT 2 · C ··· ... (4)
【００１９】しかし、図１６の状態の部分も最終的には
温度ＴＥになるので、この第１回目射出部分のヒケ量も
加える必要がある。この加えるヒケ量は次式となる。 ボス部ヒケ量△ＭB4＝α・△Ｔ３・Ｂ ・・・・・・・・・・（５） リブ部ヒケ量△ＭR4＝α・△Ｔ３・Ｃ ・・・・・・・・・・（６） 但し、△Ｔ３＝ＴＣ−ＴＥ したがって、ボス部、リブ部のそれぞれの合計ヒケ量
は、前記式の （３）＋（５）、（４）＋（６）とな
る。この二重射出成形後の最終的ヒケ量を模式的に図１
８に示す。However, since the portion in the state of FIG. 16 finally reaches the temperature TE, it is also necessary to add the amount of sink mark of this first injection portion. The amount of sink marks added is given by the following equation. Boss sink amount ΔM B4 = α ・ ΔT3 ・ B ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ (5) Rib sink amount ΔM R4 = α ・ △ T3 ・ C ・ ・ ・ ・ ・ ・ ・ ・(6) However, ΔT3 = TC-TE Therefore, the total sink amount of each of the boss portion and the rib portion is (3) + (5), (4) + (6) in the above equation. The final sink amount after this double injection molding is schematically shown in FIG.
8 shows.
【００２０】ここで、Ａ＝３ｍｍ，Ｂ＝５ｍｍ，Ｃ＝７
ｍｍ，ＴＲ＝２５０℃，ＴＣ＝１８０℃，ＴＥ＝２０
℃，α＝３×１０-5／℃とすると、（イ）通常の１回成
形でのヒケ量は、（１）、（２）式より、 ボス部：０．０３４５ｍｍ リブ部：０．０４８３ｍｍ となる。 （ロ）本発明の二重射出成形をした場合のヒケ量は、
（３）＋（５）式、（４）＋（６）式より、 ボス部：０．０００１＋０．０２４０＝０．０２４１ｍ
ｍ リブ部：０．０００１＋０．０３３６＝０．０３３７ｍ
ｍ となり、理論的にも本発明がヒケ量の少ない方法で
あることが明らかである。Here, A = 3 mm, B = 5 mm, C = 7
mm, TR = 250 ° C., TC = 180 ° C., TE = 20
C, α = 3 × 10 −5 / ° C., (a) The amount of sink mark in the normal single molding is from the formulas (1) and (2): boss part: 0.0345 mm rib part: 0.0483 mm Becomes (B) The amount of sink marks when the double injection molding of the present invention is
From the expressions (3) + (5) and (4) + (6), the boss portion: 0.0001 + 0.0240 = 0.0241m
m Rib part: 0.0001 + 0.0336 = 0.0337m
m, which is theoretically clear that the present invention is a method with a small amount of sink marks.
【００２１】さらに、本発明の二重射出成形によるヒケ
を少なくする別の作用について述べる。これは、射出充
填する樹脂を発泡、未発泡の状態にて成形する方法に関
する。すなわち、第１回目の所定のキャビティ（図１
５）に射出する時、発泡させた樹脂を注入すれば図１６
のようなヒケは発生しない。したがって、この場合には
次の第２回目の射出時に厚さＸの均一部分に溶融樹脂を
射出すれば良いので、ヒケ発生部分は無いため冷却によ
る収縮も均一に行われる。第２回目の射出時にも発泡し
た材料を注入すると表面にスワ−ルマ−クが表れ、外観
を損ねるので、好ましくは第２回目に発泡しない材料を
注入する方が良い。また、第１回目および第２回目の溶
融樹脂の充填を同一の射出装置と金型により一貫して行
えば、生産性を向上させることができる。Further, another function of reducing the sink mark by the double injection molding of the present invention will be described. This relates to a method of molding a resin to be injected and filled in a foamed or unfoamed state. That is, the first predetermined cavity (see FIG.
When injecting foamed resin when injecting into 5),
The sink mark like does not occur. Therefore, in this case, since it is sufficient to inject the molten resin into the uniform portion having the thickness X at the time of the next second injection, since there is no sinking portion, the contraction due to cooling is uniformly performed. When the foamed material is injected also during the second injection, swirl marks appear on the surface and the appearance is impaired. Therefore, it is preferable to inject the non-foamed material in the second injection. Further, if the first and second fillings of the molten resin are carried out consistently by the same injection device and mold, the productivity can be improved.
【００２２】次に、本発明に係わる三重射出成形では、
前述の二重射出成形で計算式にて説明したヒケ量低減作
用が、三回目射出することによりさらに加わり、ヒケが
低減される。また、推定ではあるが、次の作用も考えら
れる。すなわち、第１回目の射出充填部のボス部等肉厚
より薄い肉厚である第２回目の射出充填部は、溶融樹脂
温度より充分低温に温度調節されている金型に接するの
で冷却速度が大きく、早期に温度が下がるので、この第
２回目の射出充填部と接する薄い肉厚である第３回目の
射出充填部も早期に温度が下がり、固化する。これによ
り、第２回目と第３回目の射出充填部は早期に固化する
とともに、強固になる。したがって、肉が厚いため冷却
速度の小さいボス部等の固化時に生じる収縮力に対し、
ボス部等の表面側部分にある第３回目の射出充填部表面
は、強度が向上しているの変形を生じることがなく、ヒ
ケ等を生じない。Next, in the triple injection molding according to the present invention,
The effect of reducing the amount of sink marks described by the calculation formula in the above-described double injection molding is further added by the third injection, and the sink marks are reduced. Although estimated, the following effects are also possible. That is, since the second injection filling portion, which is thinner than the wall thickness of the boss portion of the first injection filling portion, contacts the mold whose temperature is sufficiently lower than the molten resin temperature, the cooling rate is Since the temperature is large and the temperature drops early, the temperature of the third injection filling part, which is in contact with the injection filling part of the second time and is thin, also drops early and solidifies. As a result, the second and third injection filling parts solidify early and become strong. Therefore, because the flesh is thick, the shrinking force generated at the time of solidification such as the boss portion with a low cooling rate,
The surface of the third injection-filled portion on the surface side portion of the boss portion or the like has improved strength, does not deform, and does not cause sink marks or the like.
【００２３】また、本発明に係わる四重射出成形では、
四回もしくはそれ以上射出するので、前述の二重射出成
形で説明したヒケ量低減の作用がさらに加わり、ヒケ量
はより低減される。また、三重射出成形で推定した、強
度向上による作用も三重射出成形以上に大きく加わる。
したがって、ボス、リブ等が大きい、あるいは厚肉の大
物部品等で、二重射出成形あるいは三重射出成形でもま
だヒケ量低減が不十分の場合には、四重射出成形は有効
である。Further, in the quadruple injection molding according to the present invention,
Since the injection is performed four times or more, the effect of reducing the sink amount described in the double injection molding is further added, and the sink amount is further reduced. In addition, the effect of strength improvement estimated by triple injection molding is added more than that of triple injection molding.
Therefore, when large parts such as bosses, ribs, or the like, or large-sized parts having a large wall thickness and the like are not sufficiently reduced in double injection molding or triple injection molding, quadruple injection molding is effective.
【００２４】[0024]
【実施例】以下に、本発明に係わるプラスチックの多重
射出成形方法の実施例につき、図面を参照して詳細に説
明する。まず、二重射出成形に関して説明する。図１に
は、二重射出成形を実施するための射出装置１１と金型
１との構成例であるシステムを模式的に示す。図示しな
い成形機には金型取付盤である固定盤２と可動盤３とが
互いに対面する状態で設けられている。可動盤３は、シ
ステムの制御装置であるコントロ−ラ２１の指令により
油圧ポンプ２２ａを介して型締用シリンダ８ａによって
固定盤２に近づく方向および遠ざかる方向に移動可能で
ある。固定盤２には、固定金型４が取り付けられ、可動
盤３には可動金型５が取り付けられている。可動金型５
と固定金型４とが、嵌合状態でキャビティ７を構成して
おり、最終成形品のキャビティ容積（位置Ｚ）に対応し
た拡大および縮小が可能である。このＺ等の位置は、位
置センサ２３ａで検出されコントロ−ラ２１により制御
される。固定金型４には、キャビティ７に開口する樹脂
通路６が設けられている。樹脂通路６はコ−ルドランナ
（溶融樹脂が成形品とともに冷却され、取り出し時に固
化されて取り出される）よりもホットランナ（金型内部
のヒ−タ等で加熱され、樹脂は溶融したままのランナで
あり、成形品取り出し時にもランナは取り出されない）
である方が良い。Embodiments of the plastic multiple injection molding method according to the present invention will now be described in detail with reference to the drawings. First, double injection molding will be described. FIG. 1 schematically shows a system which is a configuration example of an injection device 11 and a mold 1 for carrying out double injection molding. The molding machine (not shown) is provided with a fixed platen 2 and a movable platen 3 which are mold mounting plates so as to face each other. The movable platen 3 is movable in a direction toward and away from the fixed platen 2 by a mold clamping cylinder 8a via a hydraulic pump 22a according to a command from a controller 21 which is a control device of the system. A fixed mold 4 is attached to the fixed platen 2, and a movable mold 5 is attached to the movable platen 3. Movable mold 5
The fixed mold 4 and the fixed mold 4 form a cavity 7 in a fitted state, and can be expanded and contracted corresponding to the cavity volume (position Z) of the final molded product. The position such as Z is detected by the position sensor 23a and controlled by the controller 21. The fixed mold 4 is provided with a resin passage 6 that opens into the cavity 7. The resin passage 6 is heated by a hot runner (heater inside the mold, etc.) rather than a cold runner (the molten resin is cooled together with the molded product and is solidified and taken out at the time of taking out), and the resin is a runner as it is in a molten state. Yes, the runner is not removed even when the molded product is taken out)
Is better.
【００２５】本実施例では可動盤３の動作によってキャ
ビティ７の拡大縮小が行われるものであるが、キャビテ
ィの拡大縮小は他のアクチュエ−タ、例えばエジェクタ
用のシリンダや別途設けた駆動シリンダなどによっても
よい。本実施例では、可動盤の動作は型締シリンダによ
って行われるが、この制御は一般の成形機に取り付けら
れている制御装置によればよい。この動作については、
シ−ケンス動作を制御装置に組み込めば良いことは明白
であるので省略する。In this embodiment, the cavity 7 is enlarged or reduced by the operation of the movable platen 3. However, the cavity is enlarged or reduced by another actuator such as a cylinder for an ejector or a drive cylinder separately provided. Good. In this embodiment, the movable platen is operated by the mold clamping cylinder, but this control may be performed by the control device attached to a general molding machine. For this behavior,
Since it is obvious that the sequence operation may be incorporated in the control device, it is omitted.
【００２６】また、図１において、射出装置１１の射出
シリンダ１３にはスクリュ１４が組み込まれており、先
端部のノズル１２から樹脂通路６を経てキャビティ７に
射出される。この射出する手段としては通常の射出装置
を使用し、キャビティ動作に合わせて第１回目の射出と
第２回目の射出を行えばよい。この射出動作はキャビテ
ィの動作（拡大縮小）に合わせた制御が行われるが、ス
クリュ１４の位置は位置センサ２３ｂで検出され、コン
トロ−ラ２１により油圧ポンプ２２ｂを介して油圧シリ
ンダ８ｂで制御される。これも機械に取り付けられてい
る制御装置にシ−ケンス動作を組み込めばよいので、こ
こではその動作について説明する。Further, in FIG. 1, a screw 14 is incorporated in the injection cylinder 13 of the injection device 11, and is injected into the cavity 7 from the nozzle 12 at the tip end through the resin passage 6. A normal injection device is used as this injection means, and the first injection and the second injection may be performed in accordance with the cavity operation. This injection operation is controlled according to the operation (enlargement / reduction) of the cavity, but the position of the screw 14 is detected by the position sensor 23b, and is controlled by the controller 21 by the hydraulic cylinder 8b via the hydraulic pump 22b. . Since the sequence operation may be incorporated into the control device attached to the machine, the operation will be described here.
【００２７】キャビティへの射出時には、ノズル１２は
金型の樹脂通路６と通じている。この状態にて、射出シ
リンダ１３に組み込まれたスクリュ１４が溶融樹脂を計
量位置ＸＭから第１回目の射出を行う。この射出される
量はスクリュストロ−クＳ１分であり、これによってス
クリュはＸ１の点まで移動する。第２回目の射出時には
スクリュはＸ１の点からＸ２の点まで移動し、ストロ−
クＳ２分だけ金型に射出する。本実施例では１回にて２
回分の射出容量ＸＭを計量しているが、第１回目の射出
のあと第２回目の計量を行い、その分を射出することも
同じ効果である。なお、第２回目の射出開始時期は、温
度センサ（キャビティ近傍の温度が分かるように設けら
れている）又はタイマ２４により、コントロ−ラ２１で
制御するのも有効である。At the time of injection into the cavity, the nozzle 12 communicates with the resin passage 6 of the mold. In this state, the screw 14 incorporated in the injection cylinder 13 injects the molten resin from the measuring position XM for the first time. This injected amount is the amount of screw stroke S1, which causes the screw to move to the point X1. During the second injection, the screw moves from the point X1 to the point X2,
Inject only into the mold for 2 minutes. In this embodiment, 2 at a time
Although the injection capacity XM for the batch is measured, the same effect can be obtained by performing the second measurement after the first injection and injecting that quantity. It is also effective to control the second injection start timing by the controller 21 by a temperature sensor (provided so that the temperature in the vicinity of the cavity can be known) or the timer 24.
【００２８】図２は、図１の射出成形動作概要を示した
ものである。（ａ）ＳＴＥＰ１ではＳ１のストロ−ク分
を第１回目の射出として金型に射出した状態、（ｂ）Ｓ
ＴＥＰ２では第１回目の状態に加え、Ｓ２のストロ−ク
分を第２回目の射出として金型に射出した状態である。
（ｃ）ＳＴＥＰ３ではその後冷却し、金型を開いて成形
品を取り出している状態である。FIG. 2 shows an outline of the injection molding operation of FIG. (A) In STEP 1, the stroke of S1 is injected into the mold as the first injection, (b) S
In TEP2, in addition to the state of the first time, the stroke of S2 is in the state of being injected into the mold as the second injection.
(C) In STEP 3, the mold is then cooled, the mold is opened, and the molded product is taken out.
【００２９】ＳＴＥＰ１からＳＴＥＰ２の詳細の動作を
図面を参照して説明する。図３は第１回目所定成形品と
第２回目射出後の最終成形品の概略を示す。図３（ａ）
は、第１回目に射出充填された所定成形品の状態である
が、このままではリブ５１やボス５２の部分の反対側に
ヒケ５３ａ、５４ｂが生じる。図３（ｂ）は第２回目の
射出充填５４が行われ最終成形品となった状態のもので
ある。第１回目の射出充填と第２回目の射出充填に関す
る実施例を以下述べる。The detailed operation of STEP1 to STEP2 will be described with reference to the drawings. FIG. 3 shows an outline of a first molded product and a final molded product after the second injection. Figure 3 (a)
Is a state of a predetermined molded product that is injection-filled for the first time, but if it is left as it is, sink marks 53a and 54b are formed on the opposite side of the rib 51 and the boss 52. FIG. 3B shows a state in which the second injection filling 54 is performed and the final molded product is obtained. An example of the first injection filling and the second injection filling will be described below.
【００３０】（二重射出成形方法における第１回目の射
出充填動作）第１回目の所定キャビティへの射出充填を
図４に示す。ここで、所定成形品となる開き量Ｙにセッ
トされたキャビティ７に（図４（ａ））、第１回目の射
出充填を行った状態（図４（ｂ））である。第１回目の
所定キャビティ容積より予め縮小したキャビティへの射
出充填を図５に示す。所定の開き量Ｙよりも縮小して開
き量Ｌ（Ｌ＜Ｙ）にセットしたキャビティ７に溶融樹脂
の射出を開始し（図５（ａ））、射出充填に伴ってキャ
ビティ７が拡大し開き量Ｙとなる所定成形品（図５
（ｂ））の状態を示す。図４の方法ではキャビティが広
いためジェッティングが生じやすい場合、空間が広いた
め流動抵抗が低く即座に発泡して表面にスワ−ルマ−ク
が大きく発生する発泡材料を使用する場合などに有効な
手段である。これは、図５の方法では射出中に抵抗が生
じるので最初から広い空間である場合よりジェッティン
グや発泡が生じ難いためである。また、射出開始時の開
き量Ｌは樹脂が流れる程度まで小さくしてもよい。(First Injection Filling Operation in Double Injection Molding Method) FIG. 4 shows the first injection filling of a predetermined cavity. Here, it is a state in which the cavity 7 set to the opening amount Y which is a predetermined molded product (FIG. 4A) is subjected to the first injection filling (FIG. 4B). FIG. 5 shows injection filling into a cavity that has been reduced in advance from the predetermined cavity volume for the first time. The injection of the molten resin is started in the cavity 7 which is set to the opening amount L (L <Y) by reducing the opening amount Y from a predetermined value (FIG. 5 (a)), and the cavity 7 expands and opens with injection filling. Predetermined molded product with quantity Y (Fig. 5
The state of (b)) is shown. The method of FIG. 4 is effective when the jetting is likely to occur due to the large cavity, and when the foaming material in which the flow resistance is low due to the large space and the swirl mark is generated immediately on the surface is used. It is a means. This is because the method of FIG. 5 causes resistance during injection, and thus jetting and foaming are less likely to occur than in the case where a wide space is initially provided. Further, the opening amount L at the time of starting the injection may be reduced to such an extent that the resin flows.
【００３１】第１回目の所定キャビティ容積より予め拡
大したキャビティへの射出充填を図６に示す。この方法
ではＹよりも拡大した開き量Ｍ（Ｍ＞Ｙ）のキャビティ
７に溶融樹脂を射出し（図６（ａ））、これを型閉じ方
向への可動金型５の移動によりキャビティ７を縮小する
ことで溶融樹脂を押しつぶし、所定の成形品になる開き
量Ｙまで樹脂を展延する（図６（ｂ））。第１回目の成
形品均一部厚さ（開き量Ｙに対応）が薄いものを図６の
方法で実施すると、薄肉部への溶融樹脂射出充填が充分
になされる。また図６の方法において、射出しながら所
定成形品まで縮小してもよい。以上の、図４〜図６を基
本とする方法で射出充填後取り出したものは、発泡材料
を用いた以外は、リブやボスの部分の反対側にヒケや凹
みが生じる。FIG. 6 shows the first injection and filling of the cavity, which has been expanded from the predetermined cavity volume in advance. In this method, molten resin is injected into the cavity 7 having an opening amount M (M> Y) that is larger than Y (FIG. 6A), and the cavity 7 is moved by moving the movable mold 5 in the mold closing direction. By shrinking, the molten resin is crushed, and the resin is spread to the opening amount Y that becomes a predetermined molded product (FIG. 6B). When the first molded product having a uniform thickness (corresponding to the opening amount Y) having a small thickness is carried out by the method shown in FIG. 6, the molten resin is sufficiently injected and filled into the thin portion. Further, in the method of FIG. 6, it is possible to reduce the size to a predetermined molded product while injecting. With the above-described method based on FIGS. 4 to 6 and taken out after injection filling, sink marks or dents are formed on the side opposite to the ribs or bosses, except that a foam material is used.
【００３２】（二重射出成形方法における第２回目の射
出充填動作）最終成形品となる第２回目の射出充填も第
１回目と同様な動作で行われればよい。最終成形品容積
まで拡大したキャビティへの第２回目の射出充填を図７
に示す。最終成形品容積となる開き量Ｚにキャビティ７
をセットし（図７（ａ））、第２回目の射出充填を行う
（図７（ｂ））。最終成形品容積以下に拡大したキャビ
ティへの第２回目の射出充填を図８に示す。第１回目の
射出充填後、最終成形品容積以下に拡大した開き量Ｕ
（Ｙ＜Ｕ＜Ｚ）のキャビティ７に射出を開始し（図８
（ａ））、射出しながら拡大し、最終成形品容積となる
開き量Ｚまで射出充填を行う（図８（ｂ））。また、射
出開始の開き量Ｕは樹脂が流れる程度まで小さくしても
よい。最終成形品容積以上に拡大したキャビティへの第
２回目の射出充填を図９に示す。第１回目の射出充填終
了後、キャビティ７を最終成形品容積以上となる開き量
Ｗ（Ｗ＞Ｚ）に拡大し、その空間に第２回目を射出後
（図９（ａ））、最終成形品容積となる開き量Ｚまで縮
小し充填を行う（図９（ｂ））。また、この方法におい
て、射出しながら最終成形品容積まで縮小してもよい。(Second Injection Filling Operation in Double Injection Molding Method) The second injection filling, which is the final molded product, may be performed by the same operation as the first injection filling operation. Figure 7 shows the second injection filling of the cavity expanded to the final molded product volume.
Shown in. Cavity 7 in opening Z, which is the final molded product volume
Is set (FIG. 7A), and the second injection filling is performed (FIG. 7B). FIG. 8 shows the second injection filling of the cavity expanded to the volume of the final molded product or less. Opening amount U expanded to less than the final molded product volume after the first injection filling
Injection is started into the cavity 7 of (Y <U <Z) (see FIG.
(A)) Then, it is expanded while being injected, and injection filling is performed up to the opening amount Z which becomes the final molded product volume (FIG. 8B). Further, the opening amount U at the start of injection may be reduced to the extent that the resin flows. FIG. 9 shows the second injection filling of the cavity expanded to the volume of the final molded product or more. After the completion of the first injection and filling, the cavity 7 is expanded to an opening amount W (W> Z) which is equal to or larger than the volume of the final molded product, and the second molding is injected into the space (FIG. 9A), and the final molding is performed. Filling is performed by reducing the opening amount Z which is the product volume (FIG. 9B). Further, in this method, the volume of the final molded product may be reduced while being injected.
【００３３】図７〜図９を基本とする方法で射出充填し
た成形品は、いずれもヒケなどが極めて少ないかあるい
は観察できないレベルであり、通常の１回成形だけの射
出充填法と比べて、表面品質は大幅に改善されている。
前述の図４〜図６は第１回目の射出充填方法であり、図
７〜図９は第２回目の射出充填の方法である。したがっ
て、本発明の二重射出成形方法においては、、第１回目
の射出方法として図４〜図６を基本とする方法の中から
一つと、第２回目の射出方法として図７〜図９を基本と
する方法の中から一つが、選択・組み合わされて行えば
よい。The molded articles injection-filled by the method based on FIGS. 7 to 9 have very few sink marks or are at an unobservable level. The surface quality is greatly improved.
4 to 6 are the first injection filling method, and FIGS. 7 to 9 are the second injection filling method. Therefore, in the double injection molding method of the present invention, one of the methods based on FIGS. 4 to 6 is used as the first injection method and FIGS. 7 to 9 are used as the second injection method. One of the basic methods may be selected and combined.
【００３４】次に、本発明に係わる二重射出成形方法の
別の実施例である、第１回目に発泡した射出を行い、第
２回目に発泡しない射出を行う例を述べる。図１０に実
施するための射出装置と金型との構成例であるシステム
を模式的に示す。なお、前記実施例と同一部品には同一
符号を付して説明は省略する。この場合、ノズル１２に
は開度量により剪断発熱を制御するロ−タリ−バルブ３
１が設けられており、コントロ−ラからの指令で電動サ
−ボモ−タ３２が開度を制御する。本例での図３（ａ）
に示す第１回目所定成形品、次に図３（ｂ）に示す最終
成形品の成形ついて、剪断発熱の制御法概要を示す図１
１で動作を説明する。すなわち、発泡剤を混入した樹脂
材料を用い、シリンダ１３の内部では樹脂の溶融温度以
上で、かつ発泡を開始する温度以下に制御し、ロ−タリ
−バルブ３１の開度を絞り気味にし第１回目の射出充填
を行う（図１１（ａ））。これは、ロ−タリ−バルブを
通過する時生じる剪断発熱により発泡温度以上の溶融樹
脂状態にして、発泡させた樹脂を充填するものである。
続いて、キャビティを拡大し、第１回目と同じ材料で、
かつシリンダ内部温度も同じに調節制御されている未発
泡の溶融樹脂を、発泡しない程度の剪断発熱量となるに
ロ−タリ−バルブ３１の開度（開き気味）にして第２回
目の射出をする（図１１（ｂ））。この発泡剤含有樹脂
材料での二重射出成形動作を図１２に示すが、第１回目
と第２回目の金型動作等についてはそれぞれ図４〜図６
と図７〜図９とから選択・組合せて行える。Next, another embodiment of the double injection molding method according to the present invention, that is, an example in which the first foaming injection is performed and the second non-foaming injection is performed will be described. FIG. 10 schematically shows a system that is an example of the configuration of an injection device and a mold for implementation. The same parts as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted. In this case, the nozzle 12 has a rotary valve 3 for controlling the shear heat generation depending on the opening degree.
1 is provided, and the electric servo motor 32 controls the opening degree by a command from the controller. FIG. 3A in this example
FIG. 1 showing the outline of the method for controlling the shear heat generation regarding the molding of the first predetermined molded product shown in FIG. 3 and the final molded product shown in FIG.
The operation will be described in 1. That is, using a resin material mixed with a foaming agent, the temperature inside the cylinder 13 is controlled to be higher than the melting temperature of the resin and lower than the temperature at which foaming starts, and the opening degree of the rotary valve 31 is narrowed down. The second injection filling is performed (FIG. 11A). This is to fill the foamed resin in a molten resin state having a foaming temperature or higher due to shearing heat generated when passing through a rotary valve.
Then, expand the cavity, using the same material as the first time,
In addition, the unexpanded molten resin whose cylinder internal temperature is also adjusted and controlled is set to the opening (opening) of the rotary valve 31 so that the shearing calorific value is such that foaming does not occur, and the second injection is performed. (FIG. 11B). The double injection molding operation using this foaming agent-containing resin material is shown in FIG. 12, and the first and second mold operations and the like are shown in FIGS.
And FIG. 7 to FIG. 9 can be selected and combined.
【００３５】なお、剪断発熱量すなわち温度調節を制御
する方法として、ロ−タリバルブによる方法を開示した
が、ノズル部分に他の可変絞りを設けて制御してもよい
し、射出速度を高速・低速にすることで発泡・未発泡を
制御してもよいし、電気抵抗発熱体や超音波発熱、高周
波加熱、赤外線加熱などの通常の加熱装置も利用するこ
ともできる。Although a method using a rotary valve has been disclosed as a method for controlling the amount of heat generated by shearing, that is, temperature control, another variable throttle may be provided in the nozzle portion for control, or the injection speed can be set to high or low. In this case, foaming / non-foaming may be controlled, or an ordinary resistance heating device such as an electric resistance heating element, ultrasonic heating, high frequency heating, infrared heating or the like may be used.
【００３６】次に、本発明に係わる三重射出成形方法に
ついて、説明する。図１９に、本実施例に適用する、射
出装置と金型との構成例であるシステムを模式的に示
す。この構成は、前述の二重射出成形方法の別の実施例
（図１０参照）と同じであり、前述実施例と同じ部品に
は同一符号を付して説明は省略する。作動に関し、三重
射出成形動作概要を図２０に示す。（ａ）ＳＴＥＰ１で
は、金型１を閉じた後、第１回目の所定キャビティ容積
７ａとなる位置に可動金型５をセットする。続いて、シ
リンダ１３内部で所定温度に加熱制御されている溶融樹
脂６１がノズル１２から漏出しない開度量０％にあるロ
ータリーバルブ３１（（ａ）の状態）を開度量１００％
（図１１（ｂ）参照）にするとともに、所定の計量位置
ＰＭにあるスクリュ１４を第１回目の射出完了となる位
置Ｐ１に移動させ、第１回目の所定射出量となるストロ
ークＱ１分の溶融樹脂６１をキャビティ７に射出充填
し、ロータリーバルブ３１の開度量０％にする（（ａ）
の状態）。続いて、（ｂ）ＳＴＥＰ２では、第２回目の
所定キャビティ容積７ｂとなる位置に可動金型５を移動
拡大し、開度量０％のロータリーバルブ３１を開度量１
００％にするとともに、位置Ｐ１にあるスクリュ１４を
第２回目の射出完了となる位置Ｐ２に移動させ、第２回
目の所定射出量となるストロークＱ２分の溶融樹脂６１
をキャビティ７に射出充填し、ロータリーバルブ３１の
開度量０％にする（（ｂ）の状態）。さらに、（ｃ）Ｓ
ＴＥＰ３では、第３回目の所定キャビティ容積７ｃとな
る位置に可動金型５を移動拡大し、開度量０％のロータ
リーバルブ３１を開度量１００％にするとともに、位置
Ｐ２にあるスクリュ１４を第３回目の射出完了となる位
置Ｐ３に移動させ、第３回目の所定射出量となるストロ
ークＱ３分の溶融樹脂６１をキャビティ７に射出充填
し、ロータリーバルブ３１の開度量０％にする（（ｃ）
の状態）。そして、（ｄ）ＳＴＥＰ４では、所定条件で
冷却後、可動金型５後退により型１を開き、三重射出成
形最終成形品６２を取り出すとともに、スクリュ１４を
所定の計量位置ＰＭに後退させる。Next, the triple injection molding method according to the present invention will be described. FIG. 19 schematically shows a system which is an example of the configuration of an injection device and a mold, which is applied to this embodiment. This structure is the same as that of the other embodiment (see FIG. 10) of the above-described double injection molding method, and the same parts as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted. Regarding the operation, an outline of triple injection molding operation is shown in FIG. (A) In STEP 1, after the mold 1 is closed, the movable mold 5 is set at a position where the first predetermined cavity volume 7a is reached. Then, the rotary valve 31 (state of (a)) at the opening amount of 0% at which the molten resin 61 whose heating is controlled to a predetermined temperature inside the cylinder 13 does not leak from the nozzle 12 is opened at 100%.
(See FIG. 11B), the screw 14 at the predetermined measuring position PM is moved to the position P1 at which the first injection is completed, and melting for the stroke Q1 at the first predetermined injection amount is performed. Resin 61 is injected and filled in the cavity 7 to make the opening amount of the rotary valve 31 0% ((a)).
State). Then, in (b) STEP2, the movable mold 5 is moved and expanded to a position where the second predetermined cavity volume 7b is reached, and the rotary valve 31 having an opening amount of 0% is opened at an opening amount of 1%.
To 100%, the screw 14 at the position P1 is moved to the position P2 at which the second injection is completed, and the molten resin 61 for the stroke Q2 at which the second predetermined injection amount is obtained.
Is injected and filled in the cavity 7, and the opening amount of the rotary valve 31 is set to 0% (state (b)). Furthermore, (c) S
In TEP3, the movable mold 5 is moved and expanded to a position where the predetermined cavity volume 7c for the third time is reached, the rotary valve 31 having the opening amount of 0% is set to 100%, and the screw 14 at the position P2 is set to the third position. The cavity 7 is moved to the position P3 where the third injection is completed, and the molten resin 61 for the stroke Q3, which is the third predetermined injection amount, is injected and filled in the cavity 7 to set the opening amount of the rotary valve 31 to 0% ((c)).
State). Then, in (d) STEP 4, after cooling under a predetermined condition, the mold 1 is opened by retracting the movable mold 5, the triple injection molded final molded product 62 is taken out, and the screw 14 is retracted to a predetermined measuring position PM.
【００３７】以上、三重射出成形動作の１例を詳述した
が、本三重射出成形動作概要のフローを図２１に示す。
第１回目射出充填から第３回目射出充填は基本的には同
様な動作であり、また各射出充填動作は上述の二重射出
成形と同様である。すなわち、第１回目射出充填動作
は、（イ）第１回目の所定キャビティ容積位置に金型を
セット後、第１回目射出充填を行い、金型は第１回目の
所定キャビティ容積位置にある、（ロ）第１回目の所定
キャビティ容積位置より縮小した位置に金型をセット
後、第１回目射出充填を行いながら第１回目の所定キャ
ビティ容積位置に金型を拡大する、（ハ）第１回目の所
定キャビティ容積位置より拡大した位置に金型をセット
後、第１回目射出を行った後、あるいは射出を行いなが
ら第１回目の所定キャビティ容積位置に金型を縮小し、
溶融樹脂を充填する、である。また、第２回目および第
３回目の射出充填動作は、上記第１回目射出充填動作の
（イ）、（ロ）、（ハ）と同様に行われる。さらに、本
三重射出成形動作は、上述の二重射出成形と同様に種々
の動作が可能であり、目的に応じて、第１回目、第２回
目および第３回目のそれぞれの射出充填動作において、
上記（イ）、（ロ）、（ハ）を組み合わせて行えば良
い。Although one example of the triple injection molding operation has been described in detail above, the flow of the outline of the triple injection molding operation is shown in FIG.
The first injection filling to the third injection filling are basically the same operation, and each injection filling operation is the same as the double injection molding described above. That is, in the first injection filling operation, (a) after the mold is set in the predetermined cavity volume position of the first time, the first injection filling is performed, and the mold is at the predetermined cavity volume position of the first time, (B) After setting the mold at a position smaller than the first predetermined cavity volume position, the mold is expanded to the first predetermined cavity volume position while performing the first injection filling. (C) First After setting the mold at a position that is larger than the predetermined cavity volume position of the first time, after performing the first injection, or reducing the mold to the predetermined cavity volume position of the first time while performing injection,
Fill with molten resin. In addition, the second and third injection filling operations are performed in the same manner as (i), (b), and (c) of the first injection filling operation described above. Further, this triple injection molding operation can perform various operations similar to the above-described double injection molding, and depending on the purpose, in each of the first, second and third injection filling operations,
The above (a), (b), and (c) may be combined.
【００３８】次に、三重射出成形の１実施例を説明す
る。図２２に三重射出成形での最終成形品６３の模式的
断面を示すが、最終成形品６３の裏面側にボス６４（直
径７ｍｍ、突き出し高さ４ｍｍ）とリブ６５を有し、底
面部厚さ６６が３．０ｍｍの円板であり、材料はＰＰ
（ポリプロピレン）樹脂である。この最終成形品６３
は、一体化成形品であり、各射出成形毎の境界面は観察
されないが、境界面相当を推定し設定すると、第１回目
成形部６７、第２回目成形部６８および第３回目成形部
６９から構成される。Next, one embodiment of triple injection molding will be described. FIG. 22 shows a schematic cross section of the final molded product 63 in triple injection molding. The final molded product 63 has a boss 64 (diameter 7 mm, protruding height 4 mm) and a rib 65 on the back surface side, and has a bottom surface thickness. 66 is a 3.0 mm disc and the material is PP
(Polypropylene) resin. This final molded product 63
Is an integrally molded product, and the boundary surface for each injection molding is not observed. However, if the boundary surface equivalent is estimated and set, the first molding part 67, the second molding part 68, and the third molding part 69. Composed of.
【００３９】作動は図２０のＳＴＥＰに従い、（ａ）Ｓ
ＴＥＰ１では、金型１を閉じた後、第１回目の所定キャ
ビティ容積７ａより約４ｍｍ固定金型４と可動金型５と
が開く状態、すなわち拡大した位置に可動金型５をセッ
トし、ロータリーバルブ３１を開度量０％から開度量１
００％にするとともに、所定の計量位置ＰＭにあるスク
リュ１４を第１回目の射出完了となる位置Ｐ１に移動す
る。これにより、第１回目の所定射出量となるストロー
クＱ１分の溶融樹脂６１である溶融ＰＰ樹脂をキャビテ
ィ７に射出し、射出後、ロータリーバルブ３１の開度量
を０％にするとともに、可動金型５を型閉じ方向に移動
させる。この移動により、射出された溶融樹脂６１を圧
縮して展延しつつ、第１回目の所定キャビティ容積７ａ
の位置にて、ボス等を有する第１回目成形部６７であ
る、キャビティ７を充填する。The operation follows (STEP in FIG. 20) (a) S
In TEP1, after the mold 1 is closed, the fixed mold 4 and the movable mold 5 are opened by about 4 mm from the first predetermined cavity volume 7a, that is, the movable mold 5 is set in an expanded position, and the rotary mold is rotated. Open the valve 31 from 0% opening to 1 opening
At the same time, the screw 14 at the predetermined measuring position PM is moved to the position P1 where the first injection is completed. As a result, the molten PP resin, which is the molten resin 61 for the stroke Q1 that is the first predetermined injection amount, is injected into the cavity 7, and after the injection, the opening amount of the rotary valve 31 is set to 0% and the movable die is moved. 5 is moved in the mold closing direction. By this movement, the injected molten resin 61 is compressed and spread, and the first predetermined cavity volume 7a
At the position of, the cavity 7, which is the first molding portion 67 having a boss or the like, is filled.
【００４０】続いて、（ｂ）ＳＴＥＰ２では、第２回目
の所定キャビティ容積７ｂより約３ｍｍ固定金型４と可
動金型５とが開く状態、すなわち拡大した位置に可動金
型５をセットし、ロータリーバルブ３１を開度量０％か
ら開度量１００％にするとともに、位置Ｐ１にあるスク
リュ１４を第２回目の射出完了となる位置Ｐ２に移動す
る。これにより、第２回目の所定射出量となるストロー
クＱ２分の溶融樹脂６１をキャビティ７に射出し、射出
後、ロータリーバルブ３１の開度量を０％にするととも
に、可動金型５を型閉じ方向に移動させる。この移動に
より、射出された溶融樹脂６１を圧縮して展延しつつ、
第２回目の所定キャビティ容積７ｂの位置にて、キャビ
ティ７を充填する。Subsequently, in (b) STEP2, the movable mold 5 is set in a state in which the fixed mold 4 and the movable mold 5 are opened by about 3 mm from the second predetermined cavity volume 7b, that is, in an expanded position, The rotary valve 31 is changed from the opening amount 0% to the opening amount 100%, and the screw 14 at the position P1 is moved to the position P2 at which the second injection is completed. As a result, the molten resin 61 for the stroke Q2, which is the second predetermined injection amount, is injected into the cavity 7. After the injection, the opening amount of the rotary valve 31 is set to 0%, and the movable mold 5 is closed in the mold closing direction. Move to. By this movement, the injected molten resin 61 is compressed and spread,
The cavity 7 is filled at the position of the second predetermined cavity volume 7b.
【００４１】次の、（ｃ）ＳＴＥＰ３では、第３回目の
所定キャビティ容積７ｃより約３ｍｍ固定金型４と可動
金型５とが開く状態に可動金型５をセットし、ロータリ
ーバルブ３１を開度量０％から開度量１００％にすると
ともに、位置Ｐ２にあるスクリュ１４を第３回目の射出
完了となる位置Ｐ３に移動する。これにより、第３回目
の所定射出量となるストロークＱ３分の溶融樹脂６１を
キャビティ７に射出し、射出後、ロータリーバルブ３１
の開度量を０％にするとともに、可動金型５を型閉じ方
向に移動させる。この移動により、射出された溶融樹脂
６１を圧縮して展延しつつ、第３回目の所定キャビティ
容積７ｃの位置にて、キャビティ７を充填する。さら
に、（ｄ）ＳＴＥＰ４では、所定条件で冷却後、可動金
型５を後退させて金型１を開き、三重射出成形最終成形
品６３を取り出すとともに、スクリュ１４を所定の計量
位置ＰＭに後退させる。In the next (c) STEP3, the movable mold 5 is set so that the fixed mold 4 and the movable mold 5 are opened by about 3 mm from the third predetermined cavity volume 7c, and the rotary valve 31 is opened. The degree of opening is changed from 0% to 100%, and the screw 14 at the position P2 is moved to the position P3 at which the third injection is completed. As a result, the molten resin 61 for the stroke Q3, which is the third predetermined injection amount, is injected into the cavity 7, and after the injection, the rotary valve 31
And the movable mold 5 is moved in the mold closing direction. By this movement, the injected molten resin 61 is compressed and spread, and the cavity 7 is filled at the position of the third predetermined cavity volume 7c. Further, in (d) STEP 4, after cooling under predetermined conditions, the movable mold 5 is retracted to open the mold 1, the triple injection molded final molded product 63 is taken out, and the screw 14 is retracted to a predetermined measuring position PM. .
【００４２】なお、本実施例では、射出装置１１は、先
端部のノズル１２にコントロールバルブ３１を設けてあ
るが、射出装置は通常の射出する手段を有する装置で良
く、所定射出量も、３回射出分計量する方法を開示した
が、１回毎にスクリュを所定の計量位置まで後退させ、
都度射出させても良い。In the present embodiment, the injection device 11 is provided with the control valve 31 on the nozzle 12 at the tip, but the injection device may be a device having a normal injection means, and the predetermined injection amount is 3 as well. Disclosed is a method of measuring the amount of injections, but each time the screw is retracted to a predetermined measuring position,
It may be ejected each time.
【００４３】以上の三重射出成形により得られた最終成
形品６３（図２２参照）の表面６３ａは、極めて綺麗で
あり、裏面側にボス６４、リブ６５を形成する部分に
も、ヒケは観察されなかった。表面６３ａの中で最もヒ
ケを生じ易い、裏面側にボス６４の表面部６３ｂの表面
粗さ計によるヒケ量測定結果を図２３に示す。本発明に
係わる事例として、上述の１実施例である事例１以外
に、底面部厚さ６６（図２２参照）が異なる、事例２お
よび事例３も加えてある。図２３中、１−、２−お
よび３−は、事例１、事例２および事例３において、
第１回目射出充填後取り出した第１回目成形部６７（図
２２参照）の表面部６３ｂのヒケ量である。他も同様で
あり、、は、第２回目成形部６８、第３回目成形部
６９の表面部６３ｂのヒケ量である。また、底面部厚さ
６６は、事例１、２および３で、それぞれ、３．０、
３．８および４．９ｍｍであり、第１回目成形部６７厚
さ（徐ボス、リブ厚さ）も同様に１．２、１．７および
２．６ｍｍであり、第２回目成形部６８および第３回目
成形部６９厚さは０．８〜１．２ｍｍである。The surface 63a of the final molded product 63 (see FIG. 22) obtained by the above triple injection molding is extremely clean, and sink marks are also observed in the portion where the boss 64 and the rib 65 are formed on the rear surface side. There wasn't. FIG. 23 shows the result of sink mark measurement by the surface roughness meter of the surface portion 63b of the boss 64 on the back surface side, which is most likely to cause sink marks on the front surface 63a. As examples related to the present invention, in addition to the above-described case 1 which is one example, cases 2 and 3 having different bottom face thicknesses 66 (see FIG. 22) are also added. In FIG. 23, 1-, 2-, and 3-in case 1, case 2, and case 3,
This is the amount of sink mark on the surface portion 63b of the first molding portion 67 (see FIG. 22) taken out after the first injection filling. The same is true for others, and is the amount of sink mark on the surface portion 63b of the second molding portion 68 and the third molding portion 69. Further, the bottom face thickness 66 is 3.0, in Cases 1, 2 and 3, respectively.
3.8 and 4.9 mm, the thickness of the first molding portion 67 (gradual boss, rib thickness) is also 1.2, 1.7 and 2.6 mm, and the second molding portion 68 and The thickness of the third molding portion 69 is 0.8 to 1.2 mm.
【００４４】このヒケ量測定結果より、三重射出成形後
のヒケ量は、３事例とも全て表面粗さ計の精度限界レベ
ルの小さい値であり、１μｍ程度以下と推定される。一
般に、人間の目で分かるヒケ量は５μｍが限界と言われ
ており、本三重射出成形後のヒケ量１μｍ程度以下は、
人目ではヒケとは判断できない。すなわち、ヒケ量ゼロ
である。From the result of measuring the amount of sink marks, it is estimated that the amount of sink marks after triple injection molding is a value at which the accuracy limit level of the surface roughness meter is small in all three cases, and is about 1 μm or less. Generally, it is said that the limit of sink mark that can be seen by human eyes is 5 μm, and the sink mark amount after this triple injection molding is about 1 μm or less,
It cannot be judged as a sink by the eye. That is, the amount of sink is zero.
【００４５】また、ヒケ量測定結果の中で、は従来の
１回射出成形を行った後のヒケに対応し、は本発明に
係わる二重射出成形を行った後のヒケに対応する。１回
射出成形でのヒケ量は、底面部厚さの影響を受けるため
一概には言えないが、二重射出成形によるヒケ量は、従
来の１回射出成形の約半分に低減され、効果の大きいこ
とが分かる。なお、三重射出成形により、従来の１回射
出成形の数十分の１以下にヒケが低減することは、射出
成形の多数化によるヒケ低減以上の改善効果があると考
えられる。このさらなる改善を推察すれば、厚肉部のボ
ス６４が無い第２回目成形部６８、第３回目成形部６９
は比較的急冷され、固化して強固になることにより、ボ
ス６４の固化時に生じる収縮力以上の強度を有すること
で、変形しない、すなわちヒケを生じない効果と考えら
れる。Further, among the sink mark amount measurement results, "" corresponds to the sink mark after the conventional single injection molding, and "" corresponds to the sink mark after the double injection molding according to the present invention. The amount of sink in single injection molding cannot be generally stated because it is affected by the thickness of the bottom surface, but the amount of sink in double injection molding is reduced to about half that of conventional single injection molding. It turns out to be big. It is considered that the triple injection molding reduces sink marks to 1 or less, which is several tens of minutes of the conventional single injection molding, and has an improvement effect more than the sink mark reduction due to the increase in injection molding. Inferring this further improvement, the second molding portion 68 and the third molding portion 69 without the thick boss 64 are provided.
It is considered that the effect of not being deformed, that is, not causing sink marks, is obtained by having a strength more than the contracting force generated when the boss 64 is solidified by being relatively rapidly cooled and solidifying to be strong.
【００４６】次に、本発明に係わる四重射出成形方法の
実施例について説明する。本実施例が適用される装置
は、前述した三重射出成形方法の実施例と同じ（図１９
参照）である。射出動作に関しては、前述の三重射出成
形方法で射出充填後、さらに、（イ）第４回目の所定キ
ャビティ容積位置に金型をセット後、第４回目射出充填
を行い、金型は第４回目の所定キャビティ容積位置にあ
る、（ロ）第４回目の所定キャビティ容積位置より縮小
した位置に金型をセット後、第４回目射出充填を行いな
がら第４回目の所定キャビティ容積位置に金型を拡大す
る、（ハ）第４回目の所定キャビティ容積位置より拡大
した位置に金型をセット後、第４回目射出を行った後、
あるいは射出を行いながら第４回目の所定キャビティ容
積位置に金型を縮小し、溶融樹脂を充填する、のいずれ
かにより、４回目の射出充填を行う。なお、さらに、５
回目以降の射出充填として、上記（イ）、（ロ）あるい
は（ハ）を行っても良い。この、四重射出成形方法は、
二重射出成形あるいは三重射出成形でもヒケ等の改善が
要求される場合、例えば、最終成形品が大物であり、か
つ、底面部厚さが厚く、しかもボス、リブ等も大きい部
品等に有効である。Next, examples of the quadruple injection molding method according to the present invention will be described. The apparatus to which this embodiment is applied is the same as the embodiment of the above-described triple injection molding method (see FIG. 19).
See). Regarding the injection operation, after the injection filling by the above-mentioned triple injection molding method, (a) the mold is set in the predetermined cavity volume position of the 4th time, and then the 4th injection filling is performed. (B) After setting the mold at a position which is smaller than the fourth predetermined cavity volume position in the predetermined cavity volume position, the fourth mold is placed at the fourth predetermined cavity volume position while performing the fourth injection filling. Enlarge, (c) After setting the mold at a position enlarged from the fourth cavity volume position of the fourth time, after performing the fourth injection,
Alternatively, the injection molding is performed for the fourth time by either reducing the mold to the predetermined cavity volume position during the fourth injection and filling the molten resin. Furthermore, 5
As the injection filling after the first time, the above (a), (b) or (c) may be performed. This quad injection molding method
When double sinking or triple injection molding requires improvement of sink marks, it is effective for parts where the final molded product is large and has a large bottom thickness and large bosses, ribs, etc. is there.
【００４７】[0047]
【発明の効果】本発明は、以上説明したように構成され
ているので、以下に記載されるような効果を奏する。ま
ず、第１回目および第２回目の樹脂充填を行う二重射出
成形では、次のとうりである。 （１）製品の軽量化を目指すために製品肉厚を薄くし、
さらに強度を確保するためリブを設けたり、製品取付け
用にビス止めするためのボスを設けたりすることにより
ヒケの生じやすい製品を、ヒケを非常に少なくあるいは
無くすことができる。したがって、外観品質のよい製品
を得ることができる。 （２）第１回目の射出は発泡成形、第２回目の射出は未
発泡成形とすることで、さらに外観品質のよい製品を得
ることが出来る。ヒケは無いがスワ−ルマ−クの生じる
通常の発泡成形品に対しても、ヒケもスワ−ルマ−クも
無く外観のよい製品が得られる。また、ロ−タリ−バル
ブの開度量による剪断発熱の制御方法は最終成形品の表
面品質に影響を与えない方法であり、同一の溶融樹脂材
料が使用できることも含めて、成形条件を幅広くするこ
とができる。 （３）１対の金型を有する１台の射出成形機（射出圧縮
成形機なども含む）でも、１回の成形サイクル（２回連
続の射出）で成形が可能であり、製造工程の大幅な短縮
が出来る。さらに、金型、射出成形機も安価な型・設備
費用にすることができるので、製品の品質を向上させて
製造原価を大幅に低減できる。Since the present invention is constructed as described above, it has the following effects. First, in the double injection molding in which the first resin filling and the second resin filling are performed, the following results are obtained. (1) To reduce the product weight, reduce the product thickness,
Further, by providing a rib for securing strength and providing a boss for fixing a screw for attaching a product, it is possible to extremely reduce or eliminate a sink in a product which is likely to cause a sink. Therefore, a product with good appearance quality can be obtained. (2) By forming the first injection by foam molding and the second injection by non-foam molding, it is possible to obtain a product with better appearance quality. Even if there is no sink mark but a normal foamed molded product in which swirl mark occurs, a product with good appearance can be obtained without sink mark or swirl mark. Also, the method of controlling the shear heat generation by the opening amount of the rotary valve is a method that does not affect the surface quality of the final molded product, and the molding conditions should be broadened, including that the same molten resin material can be used. You can (3) Even a single injection molding machine (including an injection compression molding machine, etc.) that has a pair of molds can perform molding in one molding cycle (two consecutive injections), greatly reducing the manufacturing process. Can be shortened. In addition, since the cost of molds and injection molding machines can be reduced to low costs for molds and equipment, the quality of products can be improved and the manufacturing cost can be significantly reduced.
【００４８】次に、三重射出成形では、下記効果が得ら
れる。 （４）射出充填を３回行うことにより、最終成形品表面
は、最もヒケ等の生じ易い、裏面側にボス等が形成され
る部分でも、ヒケ量は１μｍ程度以下、すなわち、人目
にはヒケがゼロ、という表面が綺麗な極めて高品質な製
品が得られる。 （５）しかも、二重射出成形と同様に、１対の金型を有
する１台の射出成形機で１回の成形サイクルで可能であ
り、製造原価を大幅に低減できる。さらに、射出充填を
４回あるいはそれ以上行う四重射出成形では、下記効果
が得られる。 （６）大きなヒケ等を生じやすい最終成形品、例えば、
大物であり、かつ、底面部厚さが厚く、しかもボス、リ
ブ等も大きい部品等でも表面側にヒケを生じることな
く、極めて高品質な外観表面が得られる。Next, the following effects can be obtained by triple injection molding. (4) By performing injection filling three times, the surface of the final molded product is most likely to have sink marks, and even in the portion where bosses are formed on the back surface side, the sink amount is about 1 μm or less, that is, the sink mark is visible to the human eye. It is an extremely high quality product with a beautiful surface with zero. (5) Moreover, as with the double injection molding, one injection molding machine having a pair of molds can perform one molding cycle, and the manufacturing cost can be significantly reduced. Furthermore, the following effects can be obtained by quadruple injection molding in which injection filling is performed four times or more. (6) Final molded products that are prone to large sink marks, for example,
Even for parts that are large and have a large bottom thickness and large bosses, ribs, etc., an extremely high-quality exterior surface can be obtained without sink marks on the surface side.
【図１】本発明の二重射出成形方法に係わる射出装置と
金型との構成例であるシステムの模式図である。FIG. 1 is a schematic diagram of a system that is an example of the configuration of an injection device and a mold according to a double injection molding method of the present invention.
【図２】本発明の二重射出成形方法に係わる射出成形動
作の概要図である。FIG. 2 is a schematic diagram of an injection molding operation according to the double injection molding method of the present invention.
【図３】本発明の二重射出成形方法に係わる第１回目所
定成形品と第２回目射出後の最終成形品の概略図であ
る。FIG. 3 is a schematic view of a first predetermined molded product and a final molded product after the second injection according to the double injection molding method of the present invention.
【図４】本発明の二重射出成形方法に係わる第１回目の
所定キャビティへの射出充填を表す図である。FIG. 4 is a diagram showing the first injection filling into a predetermined cavity according to the double injection molding method of the present invention.
【図５】本発明の二重射出成形方法に係わる第１回目の
所定キャビティ容積より予め縮小したキャビティへの射
出充填を表す図である。FIG. 5 is a diagram showing injection filling into a cavity that has been reduced in advance from the first predetermined cavity volume according to the double injection molding method of the present invention.
【図６】本発明の二重射出成形方法に係わる第１回目の
所定キャビティ容積より予め拡大したキャビティへの射
出充填を表す図である。FIG. 6 is a diagram showing injection filling into a cavity which has been enlarged in advance from the first predetermined cavity volume according to the double injection molding method of the present invention.
【図７】本発明の二重射出成形方法に係わる最終成形品
容積まで拡大したキャビティへの第２回目の射出充填を
表す図である。FIG. 7 is a diagram showing the second injection filling of the cavity expanded to the final molded product volume according to the double injection molding method of the present invention.
【図８】本発明の二重射出成形方法に係わる最終成形品
容積以下に拡大したキャビティへの第２回目の射出充填
を表す図である。FIG. 8 is a diagram showing a second injection filling of a cavity expanded to a volume of a final molded product or less according to the double injection molding method of the present invention.
【図９】本発明の二重射出成形方法に係わる最終成形品
容積以上に拡大したキャビティへの第２回目の射出充填
を表す図である。FIG. 9 is a diagram showing a second injection filling of a cavity expanded to a volume of a final molded product or more according to the double injection molding method of the present invention.
【図１０】本発明の二重射出成形方法に係わる射出装置
と金型との構成例であるシステムの模式図である。FIG. 10 is a schematic diagram of a system that is an example of the configuration of an injection device and a mold according to the double injection molding method of the present invention.
【図１１】本発明の二重射出成形方法に係わる剪断発熱
の制御法概要図である。FIG. 11 is a schematic diagram of a method for controlling shearing heat generation according to the double injection molding method of the present invention.
【図１２】本発明の二重射出成形方法に係わる発泡剤含
有樹脂材料での二重射出成形動作図である。FIG. 12 is a double injection molding operation diagram with a foaming agent-containing resin material according to the double injection molding method of the present invention.
【図１３】通常の１回成形での金型の成形品キャビティ
図である。FIG. 13 is a cavity diagram of a molded product of a mold in normal single molding.
【図１４】通常の１回成形でのヒケ状態の模式図であ
る。FIG. 14 is a schematic view of a sink state in a normal single molding.
【図１５】本発明の二重射出成形方法に係わる第１回目
射出の所定キャビティ図である。FIG. 15 is a predetermined cavity view of the first injection according to the double injection molding method of the present invention.
【図１６】本発明の二重射出成形方法に係わる第１回目
射出充填後の温度ＴＣにおける収縮状態の模式図であ
る。FIG. 16 is a schematic diagram of a contracted state at a temperature TC after the first injection filling according to the double injection molding method of the present invention.
【図１７】本発明の二重射出成形方法に係わる第２回目
の追加射出部分を示す図である。FIG. 17 is a diagram showing a second additional injection portion relating to the double injection molding method of the present invention.
【図１８】本発明の二重射出成形方法に係わる二重射出
後の最終的ヒケ量を示す模式図である。FIG. 18 is a schematic diagram showing the final sink amount after double injection according to the double injection molding method of the present invention.
【図１９】本発明の三重射出成形方法に係わる射出装置
と金型との構成例であるシステムの模式図である。FIG. 19 is a schematic diagram of a system that is an example of the configuration of an injection device and a mold according to the triple injection molding method of the present invention.
【図２０】本発明の三重射出成形方法に係わる射出成形
動作概要図である。FIG. 20 is a schematic view of an injection molding operation according to the triple injection molding method of the present invention.
【図２１】本発明の三重射出成形方法に係わる射出成形
動作概要のフローである。FIG. 21 is a flow chart of the outline of the injection molding operation according to the triple injection molding method of the present invention.
【図２２】本発明の三重射出成形方法に係わる最終成形
品の模式的断面図である。FIG. 22 is a schematic cross-sectional view of a final molded product according to the triple injection molding method of the present invention.
【図２３】本発明の三重射出成形方法に係わるヒケ量測
定結果を表す図である。FIG. 23 is a diagram showing the result of sink amount measurement according to the triple injection molding method of the present invention.
１ 金型 ２ 固定盤 ３ 可動盤 ４ 固定金型 ５ 可動金型 ６ 樹脂通路 ７ キャビティ １１ 射出装置 １２ ノズル １３ シリンダ １４ スクリュ ３１ コントロ−ルバルブ 1 Mold 2 Fixed Plate 3 Movable Plate 4 Fixed Mold 5 Movable Mold 6 Resin Passage 7 Cavity 11 Injection Device 12 Nozzle 13 Cylinder 14 Screw 31 Control Valve
Claims (18)
を有するプラスチック成形品の成形方法において、
（イ）最終成形品容積より小さい所定のキャビティ容積
を設定し、そのキャビティに第１回目の溶融樹脂の射出
充填を行い、（ロ）その後に、最終成形品容積となる第
２回目の溶融樹脂の射出充填を行う、工程から成ること
を特徴とするプラスチックの多重射出成形方法。1. A method of molding a plastic molded article having a thick portion such as a rib or a boss partially,
(A) A predetermined cavity volume smaller than the volume of the final molded product is set, and the cavity is injected and filled with the molten resin for the first time, and (b) after that, the molten resin for the second time becomes the volume of the final molded product. A method for multiple injection molding of plastics, comprising the steps of:
キャビティ容積より、予め縮小したキャビティに溶融樹
脂を射出充填しながら、第１回目の所定のキャビティ容
積まで拡大を行う請求項１記載のプラスチックの多重射
出成形方法。2. The first injection filling step according to claim 1, wherein while the molten resin is injected and filled into a cavity that has been reduced in size from a predetermined cavity volume in advance, the cavity is expanded to the first predetermined cavity volume. Multiple injection molding method for plastics.
キャビティ容積より、予め拡大したキャビティに溶融樹
脂射出を行った後、あるいは行いながら、第１回目の所
定のキャビティ容積まで縮小し充填する請求項１記載の
プラスチックの多重射出成形方法。3. The first injection and filling step, after the molten resin is injected into a cavity that has been expanded in advance from a predetermined cavity volume, or while the molten resin is being injected, the first cavity is reduced to the predetermined cavity volume and then filled. The multiple injection molding method for a plastic according to claim 1.
終成形品容積まで拡大し、その拡大したキャビティに第
２回目の溶融樹脂射出充填を行う請求項１〜３のいずれ
か１項に記載のプラスチックの多重射出成形方法。4. The method according to claim 1, wherein after the first injection filling, the cavity is expanded to the volume of the final molded product, and the expanded cavity is subjected to the second molten resin injection filling. Multiple injection molding method for plastics.
終成形品容積以下に拡大し、その拡大したキャビティに
第２回目の溶融樹脂を射出充填しながら、最終成形品容
積まで拡大を行う請求項１〜３のいずれか１項に記載の
プラスチックの多重射出成形方法。5. After the first injection and filling, the cavity is expanded to the volume of the final molded product or less, and the expanded cavity is injected and filled with the molten resin for the second time, and the volume of the final molded product is expanded. Item 4. A multiple injection molding method for plastic according to any one of items 1 to 3.
終成形品容積以上に拡大し、その拡大したキャビティに
第２回目の溶融樹脂射出を行った後、あるいは、行いな
がら最終成形品容積まで縮小し充填する請求項１〜３の
いずれか１項に記載のプラスチックの多重射出成形方
法。6. After the first injection and filling, the cavity is expanded to a volume of the final molded product or more, and the expanded cavity is subjected to the second molten resin injection, or while performing, up to the volume of the final molded product. The method for multiple injection molding of plastic according to any one of claims 1 to 3, which is performed by reducing and filling.
は発泡した状態であり、第２回目の溶融樹脂が射出され
た成形品部は発泡していない状態である請求項１〜６の
いずれか１項に記載のプラスチックの多重射出成形方
法。7. The molded product injected with the first molten resin is in a foamed state, and the molded product part injected with the second molten resin is in a non-foamed state. The multiple injection molding method for plastic according to any one of 1.
脂は同一の材料である請求項１〜７のいずれか１項に記
載のプラスチックの多重射出成形方法。8. The method for multiple injection molding of plastics according to claim 1, wherein the molten resins injected in the first and second injections are the same material.
出充填を、同一の射出装置および金型により行う請求項
１〜８のいずれか１項に記載のプラスチックの多重射出
成形方法。9. The method for multiple injection molding of plastics according to claim 1, wherein the first injection filling and the second injection filling are performed by the same injection device and mold.
部を有するプラスチック成形品の成形方法において、
（イ）キャビティを第１回目の所定キャビティ容積に設
定し、溶融樹脂を射出充填する第１工程、（ロ）キャビ
ティを第２回目の所定キャビティ容積まで拡大し、溶融
樹脂を射出充填する第２工程、（ハ）キャビティを第３
回目の所定キャビティ容積まで拡大し、溶融樹脂を射出
充填する第３工程、以上の工程からなることを特徴とす
るプラスチックの多重射出成形方法。10. A method of molding a plastic molded article having a thick portion such as a rib or a boss partially,
(A) The first step of setting the cavity to the predetermined cavity volume for the first time and injecting and filling the molten resin with the first step, and (b) the second step of expanding the cavity to the predetermined cavity volume of the second time and injecting and filling the molten resin with the second step. Process, (c) Cavity third
A multiple injection molding method for plastics, comprising the third step of expanding to a predetermined cavity volume for the first time and injecting and filling the molten resin.
定キャビティ容積より縮小し、溶融樹脂を射出充填しな
がら第１回目の所定キャビティ容積まで拡大する第１工
程、である請求項１０記載のプラスチックの多重射出成
形方法。11. The method according to claim 10, wherein (a) is a first step in which the cavity is reduced from a predetermined cavity volume of the first time, and is expanded to the first cavity volume of the first time while injecting and filling the molten resin. Multiple injection molding method for plastics.
定キャビティ容積より拡大し、溶融樹脂を射出した後、
あるいは溶融樹脂を射出しながら、第１回目の所定キャ
ビティ容積まで縮小し充填する第１工程、である請求項
１０記載のプラスチックの多重射出成形方法。12. In (a), after the cavity is expanded from the predetermined cavity volume of the first time and the molten resin is injected,
11. The multiple injection molding method for plastics according to claim 10, which is a first step of reducing and filling a predetermined cavity volume for the first time while injecting a molten resin.
定キャビティ容積より縮小し、溶融樹脂を射出充填しな
がら第２回目の所定キャビティ容積まで拡大する第２工
程、である請求項１０〜１２のいずれか１項に記載のプ
ラスチックの多重射出成形方法。13. The step (b) is the second step of reducing the cavity from the predetermined cavity volume of the second time and expanding the cavity to the predetermined cavity volume of the second time while injecting and filling the molten resin. 13. The method for multiple injection molding of plastic according to any one of 12 above.
定キャビティ容積より拡大し、溶融樹脂を射出した後、
あるいは溶融樹脂を射出しながら、第２回目の所定キャ
ビティ容積まで縮小し充填する第２工程、である請求項
１０〜１２のいずれか１項に記載のプラスチックの多重
射出成形方法。14. In (b), after the cavity is expanded from the second predetermined cavity volume and the molten resin is injected,
Alternatively, the multiple injection molding method for plastic according to any one of claims 10 to 12, which is a second step of reducing and filling a predetermined cavity volume in a second time while injecting a molten resin.
定キャビティ容積より縮小し、溶融樹脂を射出充填しな
がら第３回目の所定キャビティ容積まで拡大する第３工
程、である請求項１０〜１４のいずれか１項に記載のプ
ラスチックの多重射出成形方法。15. The step (c) is the third step of reducing the cavity from a predetermined cavity volume of the third time and expanding the cavity to the predetermined cavity volume of the third time while injecting and filling the molten resin. 15. The multiple injection molding method for plastic according to any one of 14 above.
定キャビティ容積より拡大し、溶融樹脂を射出した後、
あるいは溶融樹脂を射出しながら、第３回目の所定キャ
ビティ容積まで縮小し充填する第３工程、である請求項
１０〜１４のいずれか１項に記載のプラスチックの多重
射出成形方法。16. In (c), the cavity is expanded from the volume of the predetermined cavity for the third time, and after the molten resin is injected,
Alternatively, the multiple injection molding method of plastic according to any one of claims 10 to 14, which is a third step of reducing and filling a predetermined cavity volume to a third cavity while injecting a molten resin.
出装置および金型により行う請求項１０〜１６のいずれ
か１項に記載のプラスチックの多重射出成形方法。17. The plastic multiple injection molding method according to claim 10, wherein the three steps of (a) to (c) are performed using the same injection device and mold.
積まで拡大し、溶融樹脂を射出充填する工程、（ホ）キ
ャビティを所定キャビティ容積より縮小し、溶融樹脂を
射出充填しながら所定キャビティ容積まで拡大する工
程、（ヘ）キャビティを所定キャビティ容積より拡大
し、溶融樹脂を射出した後、あるいは溶融樹脂を射出し
ながら、所定キャビティ容積まで縮小し充填する工程、
の３工程において、（ハ）の第３工程後、さらに、
（ニ）〜（へ）のいずれか１工程を少なくとも１回行う
請求項１０〜１７のいずれか１項に記載のプラスチック
の多重射出成形方法。18. (d) A step of expanding the cavity to a predetermined cavity volume and injecting and filling the molten resin, (e) Reducing the cavity volume from the predetermined cavity volume, and expanding to the predetermined cavity volume while injecting and filling the molten resin. Step (f) expanding the cavity beyond a predetermined cavity volume and injecting the molten resin, or while injecting the molten resin, reducing the volume to a predetermined cavity volume and filling the cavity;
In the three steps of (a), after the third step of (c),
The multiple injection molding method for a plastic according to any one of claims 10 to 17, wherein any one of the steps (d) to (v) is performed at least once.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20582293A JPH0724867A (en) | 1993-05-10 | 1993-07-28 | Multiple injection molding of plastic |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13257093 | 1993-05-10 | ||
| JP5-132570 | 1993-05-10 | ||
| JP20582293A JPH0724867A (en) | 1993-05-10 | 1993-07-28 | Multiple injection molding of plastic |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0724867A true JPH0724867A (en) | 1995-01-27 |
Family
ID=26467112
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20582293A Pending JPH0724867A (en) | 1993-05-10 | 1993-07-28 | Multiple injection molding of plastic |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0724867A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012086513A (en) * | 2010-10-22 | 2012-05-10 | Mazda Motor Corp | Method of molding resin molded article |
| JP2012113560A (en) * | 2010-11-25 | 2012-06-14 | Toyota Motor Corp | Method for manufacturing vehicle pedal |
| JP2012132513A (en) * | 2010-12-22 | 2012-07-12 | Nsk Ltd | Method for manufacturing toroidal type continuously variable transmission |
| CN113071056A (en) * | 2021-03-16 | 2021-07-06 | 苏州海栎森视觉有限公司 | Thick wall injection molding process |
| CN114103005A (en) * | 2021-11-10 | 2022-03-01 | 浙江长珑车灯股份有限公司 | Three-time forming injection mold and forming method for thick-wall optical element |
-
1993
- 1993-07-28 JP JP20582293A patent/JPH0724867A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012086513A (en) * | 2010-10-22 | 2012-05-10 | Mazda Motor Corp | Method of molding resin molded article |
| JP2012113560A (en) * | 2010-11-25 | 2012-06-14 | Toyota Motor Corp | Method for manufacturing vehicle pedal |
| JP2012132513A (en) * | 2010-12-22 | 2012-07-12 | Nsk Ltd | Method for manufacturing toroidal type continuously variable transmission |
| CN113071056A (en) * | 2021-03-16 | 2021-07-06 | 苏州海栎森视觉有限公司 | Thick wall injection molding process |
| CN114103005A (en) * | 2021-11-10 | 2022-03-01 | 浙江长珑车灯股份有限公司 | Three-time forming injection mold and forming method for thick-wall optical element |
| CN114103005B (en) * | 2021-11-10 | 2023-09-19 | 浙江长珑车灯股份有限公司 | Three-time molding injection mold and molding method for thick-wall optical element |
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