JP3615650B2 - Gas assist injection molding method and gas assist injection molding apparatus - Google Patents

Gas assist injection molding method and gas assist injection molding apparatus Download PDF

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Publication number
JP3615650B2
JP3615650B2 JP4105098A JP4105098A JP3615650B2 JP 3615650 B2 JP3615650 B2 JP 3615650B2 JP 4105098 A JP4105098 A JP 4105098A JP 4105098 A JP4105098 A JP 4105098A JP 3615650 B2 JP3615650 B2 JP 3615650B2
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Prior art keywords
gas
cavity
screw
injection
mold
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JPH11221835A (en
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吉哉 谷口
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東洋機械金属株式会社
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17Component parts, details or accessories; Auxiliary operations
    • B29C45/1703Introducing an auxiliary fluid into the mould
    • B29C45/1704Introducing an auxiliary fluid into the mould the fluid being introduced into the interior of the injected material which is still in a molten state, e.g. for producing hollow articles
    • B29C45/1711Introducing an auxiliary fluid into the mould the fluid being introduced into the interior of the injected material which is still in a molten state, e.g. for producing hollow articles and removing excess material from the mould cavity by the introduced fluid, e.g. to an overflow cavity
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B29WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29CSHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/17Component parts, details or accessories; Auxiliary operations
    • B29C45/1703Introducing an auxiliary fluid into the mould
    • B29C45/1704Introducing an auxiliary fluid into the mould the fluid being introduced into the interior of the injected material which is still in a molten state, e.g. for producing hollow articles
    • B29C45/1711Introducing an auxiliary fluid into the mould the fluid being introduced into the interior of the injected material which is still in a molten state, e.g. for producing hollow articles and removing excess material from the mould cavity by the introduced fluid, e.g. to an overflow cavity
    • B29C2045/1712Introducing an auxiliary fluid into the mould the fluid being introduced into the interior of the injected material which is still in a molten state, e.g. for producing hollow articles and removing excess material from the mould cavity by the introduced fluid, e.g. to an overflow cavity plastic material flowing back into the injection unit

Description

【0001】
【発明の属する技術分野】
本発明は、ガスアシスト式の射出成形法及び射出成形装置に関するものであり、特に溶融樹脂の無駄の少ない方法,装置に関するものである。
【0002】
【従来の技術】
射出成形法は射出ユニットにより溶融樹脂を金型のキャビティに射出する成形法である。射出成形用の型の設計では、「ひけ」や「反り」防止のためにできるだけ均一な肉厚にすることが必要であり、そのために金型に肉盗みを施す複雑な加工が余儀なくされ金型製造費が高くなり、メンテナンスの手間も大きくなる。
【0003】
そこで、このような問題点を解消するための手段としてガスアシスト射出成形法が開発された。図2は従来のガスアシスト射出成形法を説明するための概念図である。図中(11)は金型であり、(12)は金型内に形成されたキャビティである。(13)は金型に設けられたガス導入口であり、キャビティ(12)に連通している。(10)はガス供給装置(10)である。
【0004】
(14)はキャビティ(12)と連通した「捨てキャビ」と呼ばれる空間であり、「捨てキャビ」(14)とキャビティ(12)との間の通路には開閉部材(15)が備えられている。
【0005】
図2(A)に示したように射出ユニット(20)により金型(11)のキャビティ(12)に溶融樹脂(P)を射出する。このときキャビティと「捨てキャビ」(14)との間の通路は開閉部材(15)により閉鎖されている。そのため、溶融樹脂(P)はキャビティ(12)に充填されるが、「捨てキャビ」(14)には充填されない(尚、通路の位置や形状により開閉部材(15)がなくても溶融樹脂(P)が「捨てキャビ」(14)に充填されないようにすることも可能である)。
【0006】
次に、開閉部材(15)を開状態としてキャビティ(12)と「捨てキャビ」(14)との間の通路を開けて、図2(B)に示したようにガス供給装置(10)から供給されたガスをガス導入口(13)を通してキャビティ(12)に充填する。ガスとしては圧縮された空気等が使用される。
【0007】
キャビティ(12)内に充填されたガスの圧力により、キャビティ内(12)の溶融樹脂(P)は圧迫され、「捨てキャビ」(14)に押出される。射出ユニット(20)側は溶融樹脂(P)を射出したスクリュ(21)が金型(11)側に押し出されているので、溶融樹脂(P)は射出ユニット(20)側に逆流することはなく「捨てキャビ」(14)に流れ込む。
【0008】
溶融樹脂(P)の「捨てキャビ」(14)への移動により、キャビティ内に中空の部分(16)ができる。この中空部(16)の位置や大きさが適当となるようにガス導入口(13)を設けると、厚肉部と薄肉部が共存していても「ひけ」や「反り」等の問題を生じにくい。
【0009】
したがって、金型製作において傾斜コア,スライドコア等の複雑な加工が不要となり、金型構造を簡略化することができる。これにより、金型製造費を安くすることができ、金型(10)のメンテナンスの手間も少なくなる。
【0010】
また、偏肉設計が可能となるので、設計上の制約事項が少なくなり自由な設計が可能となる。例えば、従来法では3,4部品にわけて成形していたものを一体で成形できることになり部品点数を減らしてコスト減を図ることができる。
【0011】
また、中空部(16)を有するので、同じ形状であれば従来の方法で成形した場合よりも成形品の重量を軽減することができる。更に、中空部(16)により金型内の樹脂量が少なくなるので、樹脂の硬化時間が短く、成形のサイクルを短くして生産性を高めることもできる。
【0012】
しかしながら、このようなガスアシスト射出成形にも問題がある。すなわち、「捨てキャビ」(14)に流れ込んだ樹脂は射出毎に捨てられており、材料費や資源の有効利用の点で好ましくない。尚、「捨てキャビ」に流れ込んだ樹脂をペレット化し、再度溶融することも考えられるが、樹脂の性格が変わってしまうので新規の樹脂材料として使用することができない。
【0013】
【発明が解決しようとする課題】
そこで、樹脂の無駄がないガスアシスト射出成形法と、そのためのガスアシスト射出成形装置が求められている。
【0014】
【課題を解決するための手段】
本発明の請求項1のガスアシスト射出成形法は、射出ユニット(20)のスクリュ (21)により金型(1)のキャビティ(2)に溶融樹脂(P)を射出した後に、該キャビティ(2)にガスを送り込み、キャビティ(2)内のガスの圧力によりキャビティ(2)内の溶融樹脂(P)を射出ユニット(20)に逆流させ、逆流した樹脂の圧力によって射出ユニット (20) のスクリュ (21) を後退させ、スクリュ (21) の後退制御はスクリュ (21) の背圧を制御することにより行うことを特徴とする。
本発明の請求項2のガスアシスト射出成形法は、射出ユニット (20) のスクリュ (21) により金型 (1) のキャビティ (2) に溶融樹脂 (P) を射出した後に、該キャビティ (2) にガスを送り込み、キャビティ (2) 内のガスの圧力によりキャビティ (2) 内の溶融樹脂を射出ユニット (20) に逆流させ、ガスの送り込み量に応じて射出ユニット (20) のスクリュ (21) を後退させ、スクリュ (21) の後退制御は後退位置あるいは後退速度を制御することにより行うことを特徴とする。
【0015】
本発明の請求項1および2のガスアシスト射出成形法によれば、キャビティ(2)に充填されたガスによってキャビティ(2)から射出された溶融樹脂(P)は、「捨てキャビ」ではなく射出ユニット(20)に逆流する。そして、射出ユニット(20)に逆流した溶融樹脂(P)は未硬化であるので次回の成形に利用することができるので、樹脂の無駄がほとんど無い。
【0017】
本発明の請求項2のガスアシスト射出成形法によれば、ガスの供給やスクリュ(21)の後退を制御して、キャビティ(2)内が過度に減圧されることを防止することができる。よって、キャビティ(2)内の溶融樹脂(P)が必要以上に逆流することを防止すると共に金型(1)に接触している溶融樹脂(P)が金型から剥がれて成形不良となることを防止することができる。
【0018】
請求項3のガスアシスト射出成形装置は、金型(1)にはキャビティ(2)に連通するガス導入口(3)が備えられており、ガス導入口(3)には加圧されたガスをキャビティ(2)に送り込むためのガス供給装置(5)が接続されており、射出ユニット (20) にはスクリュ (21) の前進,後退を司る射出用サーボモータが備えられており、ガス供給装置 (5) とガス導入口 (3) との間にはガス流入計が設けられており、ガス流入計により測定されたガスの充填量に対応して射出ユニット (20) のスクリュ (21) を所定の位置まで後退させるように射出用サーボモータを制御することを特徴とする。
【0019】
これによれば、ガス供給装置(5)によってキャビティ(2)にガスを充填して、キャビティ(2)内の溶融樹脂(P)を射出ユニット(20)に逆流させるという上記請求項のガスアシスト射出成形法を容易に実施することができる。
【0021】
また、スクリュ (21) を後退させることにより逆流する溶融樹脂(P)の圧力が適当な範囲となるように制御することができ、上記請求項2のガスアシスト射出成形法を容易に実施することができる。
【0022】
【発明の実施の形態】
以下、本発明を好適な実施例を用いて説明する。
[実施例]
図1は本実施例を説明するための図である。
【0023】
図中において(1)は金型、(2)は金型(1)に形成されたキャビティである。(3)は金型(1)に設けられたガス導入口であり、キャビティ(2)と連続している。また、ガス導入口(3)にはガス供給装置(5)が接続されている。ガス導入口(3)の位置や数は成形品を中空にする箇所の位置,形状,数等により定められる。金型(1)には従来のような「捨てキャビ」は備えられていない。
【0024】
ガス供給装置(5)としては、実施例ではガスとしてはポンプにより圧縮されたエアタンク内の空気を用いたが、高圧窒素ガス等を利用することもできる。
【0025】
まず、図1(A)に示すように、射出ユニットのスクリュを前進させることにより、加熱筒の先端部に蓄えられた溶融樹脂(P)をキャビティ(2)に射出する。その後、図1(B)に示したようにガス供給装置(5)よりガス導入口(3)を通ってキャビティ(2)にガスを供給する。
【0026】
キャビティ(2)内に充填されたガスによりキャビティ(2)内の溶融樹脂(P)は圧迫を受けるが、従来のような「捨てキャビ」はないので、溶融樹脂(P)は加熱筒(22)に逆流する。
【0027】
溶融樹脂(P)の逆流により従来のガスアシスト射出成形法と同様に中空部(4)が形成され、ガスアシスト射出成形法の長所はそのまま活かすことができる。
【0028】
逆流した溶融樹脂(P)は未硬化であるので次回の射出に利用することができ、樹脂を無駄なく有効に利用することができる。これにより、材料費の低減や資源の有効利用を図ることができる。又、次回の射出の際には成形品に使用された分だけ溶融樹脂(P)を新たに補充すればよいので、必要な量の溶融樹脂(P)が溜まるまでの時間が短く、成形のサイクルを速くすることができる。
【0029】
ガス充填時には加熱筒に溶融樹脂(P)が逆流することになるが、スクリュはガスの送り込み量に応じて能動的に後退させてもよいし、スクリュを自由に進退できるようにしておいて逆流した樹脂圧を受けた際に受動的に後退するようにしてもよい。
【0030】
スクリュの後退がガスの充填量に対して速すぎるとキャビティ内が大きく減圧され、金型と接触している溶融樹脂(P)が剥がれ落ちたり、凹む等して成形品の不良の原因となる。そこで、このような弊害が生じないように制御装置により逆流する樹脂の圧力を制御している。
【0031】
具体的には、本実施例ではガス供給装置(5)とガス導入口(3)との間に設けたガス流入計によりガスの充填量を測定し、ガス充填量に対応してスクリュ(21)を所定の位置まで後退させるようにスクリュ(21)の前進,後退を司る射出用サーボモータを制御することにより、逆流する樹脂の圧力を制御している。
【0032】
スクリュの後退制御は実施例のように後退位置を制御してもよいが、後退速度の制御やスクリュの背圧を制御してもよい。更に、スクリュの後退の制御に代えて、又はスクリュの後退の制御と共にガスの充填速度,ガス圧等を制御することにより逆流する樹脂の圧力を制御してもよい。
【0033】
尚、射出後に型を冷却してキャビティ内の溶融樹脂(P)がある程度硬化した後に型を開いて成形品を取り出すのは従来と同様であるが、「捨てキャビ」の樹脂を捨てて次回の射出に備える必要がないので、その分の手間を省くことができる。
【0034】
【発明の効果】
以上述べたように、本発明によりガスアシスト射出成形法において、成形品に用いられない無駄な樹脂の量を大幅に減少させ、材料費の軽減と資源の有効利用を図ることができる。又、次回の射出のために新たに補充しなければならない樹脂量が少なくてよいので、成形のサイクルを速くすることができ、生産効率が向上する。
【図面の簡単な説明】
【図1】本発明のガスアシスト射出成形法を説明する図。
【図2】従来のガスアシスト射出成形法を説明する図。
【符号の説明】
(1) 金型
(2) キャビティ
(3) ガス導入口
(5) ガス供給装置
(20) 射出ユニット
(21) スクリュ
(22) 加熱筒
(P) 溶融樹脂
[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gas assist type injection molding method and an injection molding apparatus, and more particularly to a method and an apparatus with little waste of molten resin.
[0002]
[Prior art]
The injection molding method is a molding method in which a molten resin is injected into a mold cavity by an injection unit. In the mold design for injection molding, it is necessary to make the wall thickness as uniform as possible to prevent “sinking” and “warping”, which necessitates complicated processing to steal the mold. Manufacturing costs will increase and maintenance efforts will also increase.
[0003]
Therefore, a gas assist injection molding method has been developed as a means for solving such problems. FIG. 2 is a conceptual diagram for explaining a conventional gas assist injection molding method. In the figure, (11) is a mold, and (12) is a cavity formed in the mold. (13) is a gas inlet provided in the mold and communicates with the cavity (12). (10) is a gas supply device (10).
[0004]
(14) is a space called “discarding cabinet” communicating with the cavity (12), and an opening / closing member (15) is provided in the passage between the “discarding cabinet” (14) and the cavity (12). .
[0005]
As shown in FIG. 2A, the molten resin (P) is injected into the cavity (12) of the mold (11) by the injection unit (20). At this time, the passage between the cavity and the “discarding mold” (14) is closed by the opening / closing member (15). Therefore, the molten resin (P) is filled in the cavity (12), but is not filled in the “discarded mold” (14) (Note that the molten resin (P) can be formed without the opening / closing member (15) depending on the position and shape of the passage. It is also possible to prevent P) from filling the “throwing mold” (14)).
[0006]
Next, the opening / closing member (15) is opened to open a passage between the cavity (12) and the “discarding mold” (14), and the gas supply device (10) is opened as shown in FIG. The supplied gas is filled into the cavity (12) through the gas inlet (13). Compressed air or the like is used as the gas.
[0007]
Due to the pressure of the gas filled in the cavity (12), the molten resin (P) in the cavity (12) is squeezed and pushed out into the “disposal mold” (14). On the injection unit (20) side, the screw (21) that injected the molten resin (P) is pushed out to the mold (11) side, so that the molten resin (P) does not flow back to the injection unit (20) side. Instead, it flows into “Abandoned mold” (14).
[0008]
By moving the molten resin (P) to the “discarding mold” (14), a hollow portion (16) is formed in the cavity. If the gas inlet (13) is provided so that the position and size of the hollow portion (16) are appropriate, problems such as "sinking" and "warping" occur even if the thick and thin portions coexist. Hard to occur.
[0009]
Therefore, complicated processing such as an inclined core and a slide core is not required in the manufacture of the mold, and the mold structure can be simplified. As a result, the mold manufacturing cost can be reduced, and the maintenance of the mold (10) can be reduced.
[0010]
In addition, since uneven thickness design is possible, design restrictions are reduced and free design is possible. For example, in the conventional method, what has been molded into three or four parts can be integrally molded, and the number of parts can be reduced to reduce costs.
[0011]
Moreover, since it has a hollow part (16), if it is the same shape, the weight of a molded article can be reduced rather than the case where it shape | molds by the conventional method. Furthermore, since the amount of resin in the mold is reduced by the hollow portion (16), the curing time of the resin can be shortened, and the molding cycle can be shortened to increase the productivity.
[0012]
However, there are problems with such gas-assisted injection molding. That is, the resin that has flowed into the “discarding mold” (14) is discarded at every injection, which is not preferable in terms of material costs and effective use of resources. Although it is possible to pelletize the resin that has flowed into the “discarded mold” and melt it again, it cannot be used as a new resin material because the properties of the resin change.
[0013]
[Problems to be solved by the invention]
Therefore, there is a need for a gas-assisted injection molding method that does not waste resin and a gas-assisted injection molding apparatus therefor.
[0014]
[Means for Solving the Problems]
According to the gas assist injection molding method of the first aspect of the present invention, after the molten resin (P) is injected into the cavity (2) of the mold (1) by the screw (21) of the injection unit (20), the cavity (2 ), The molten resin (P) in the cavity (2) is caused to flow back to the injection unit (20) by the gas pressure in the cavity (2), and the screw of the injection unit (20) is caused by the pressure of the resin that has flowed back. (21) to retract the retraction control of the screw (21) and performing by controlling the back pressure of the screw (21).
According to the gas assist injection molding method of claim 2 of the present invention, after the molten resin (P) is injected into the cavity (2) of the mold (1) by the screw (21) of the injection unit (20) , the cavity (2 ) to feed a gas, the cavity (allowed to flow back into the injection unit the molten resin in the cavity (2) by the pressure of gas in 2) (20), the screw of the injection unit in accordance with the amount infeed of gas (20) (21 ) , And the backward control of the screw (21) is performed by controlling the reverse position or the reverse speed.
[0015]
According to the gas-assisted injection molding method of claims 1 and 2 of the present invention, the molten resin (P) injected from the cavity (2) by the gas filled in the cavity (2) is not "discarded mold" but injected. Backflow to unit (20). The molten resin (P) flowing back to the injection unit (20) is uncured and can be used for the next molding, so there is almost no waste of resin.
[0017]
According to the gas-assisted injection molding method of the second aspect of the present invention, it is possible to prevent the inside of the cavity (2) from being excessively decompressed by controlling the supply of gas and the retreat of the screw (21). Therefore, the molten resin (P) in the cavity (2) is prevented from flowing back more than necessary, and the molten resin (P) in contact with the mold (1) is peeled off from the mold, resulting in a molding failure. Can be prevented.
[0018]
In the gas assist injection molding apparatus according to claim 3, the mold (1) is provided with a gas introduction port (3) communicating with the cavity (2), and the gas introduction port (3) has a pressurized gas. Is connected to the gas supply device (5), and the injection unit (20) is equipped with an injection servo motor that controls the forward and backward movement of the screw (21). A gas inflow meter is provided between the device (5) and the gas inlet (3), and the screw (21) of the injection unit (20) corresponding to the gas filling amount measured by the gas inflow meter. The injection servomotor is controlled so as to retract the valve to a predetermined position .
[0019]
According to this, the gas supply device (5) filled with gas to a cavity (2), of the claim 2 that is reverse flow cavity (2) molten resin (P) in the injection unit (20) Gas The assist injection molding method can be easily performed.
[0021]
Further, by reversing the screw (21) , the pressure of the molten resin (P) flowing backward can be controlled to be within an appropriate range, and the gas assist injection molding method of claim 2 can be easily carried out. Can do.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to preferred embodiments.
[Example]
FIG. 1 is a diagram for explaining the present embodiment.
[0023]
In the figure, (1) is a mold and (2) is a cavity formed in the mold (1). (3) is a gas inlet provided in the mold (1) and is continuous with the cavity (2). A gas supply device (5) is connected to the gas introduction port (3). The position and number of gas inlets (3) are determined by the position, shape, number, etc. of the location where the molded product is hollowed out. The mold (1) is not provided with the conventional “discarding mold”.
[0024]
In the embodiment, as the gas supply device (5), air in the air tank compressed by a pump is used as the gas, but high-pressure nitrogen gas or the like can also be used.
[0025]
First, as shown in FIG. 1A, the molten resin (P) stored at the tip of the heating cylinder is injected into the cavity (2) by advancing the screw of the injection unit. Thereafter, as shown in FIG. 1B, gas is supplied from the gas supply device (5) to the cavity (2) through the gas inlet (3).
[0026]
Although the molten resin (P) in the cavity (2) is pressed by the gas filled in the cavity (2), there is no “discarded mold” as in the prior art, so the molten resin (P) is heated by the heating cylinder (22 ) Backflow.
[0027]
The hollow portion (4) is formed by the back flow of the molten resin (P) as in the conventional gas assist injection molding method, and the advantages of the gas assist injection molding method can be utilized as they are.
[0028]
Since the backflowed molten resin (P) is uncured, it can be used for the next injection, and the resin can be used effectively without waste. Thereby, reduction of material cost and effective utilization of resources can be aimed at. In addition, at the time of the next injection, the molten resin (P) needs only to be replenished by the amount used for the molded product, so the time required for the required amount of molten resin (P) to accumulate is short, The cycle can be made faster.
[0029]
When the gas is filled, the molten resin (P) flows backward into the heating cylinder. However, the screw may be actively retracted according to the amount of gas fed, or the screw may be moved back and forth freely. When the resin pressure is applied, it may be passively retracted.
[0030]
If the screw retreats too quickly with respect to the gas filling amount, the inside of the cavity is greatly decompressed, and the molten resin (P) in contact with the mold is peeled off or dented, causing defective molded products. . Therefore, the pressure of the resin flowing backward is controlled by the control device so that such a problem does not occur.
[0031]
Specifically, in this embodiment, the amount of gas filling is measured by a gas inflow meter provided between the gas supply device (5) and the gas inlet (3), and a screw (21 ) Is moved back to a predetermined position, the pressure of the resin flowing backward is controlled by controlling the injection servo motor that controls the advance and retreat of the screw (21).
[0032]
The screw retreat control may control the retreat position as in the embodiment, but may control the retreat speed or the back pressure of the screw. Furthermore, the pressure of the resin that flows backward may be controlled by controlling the gas filling speed, the gas pressure, or the like instead of controlling the screw retreating or together with the screw retreating control.
[0033]
The mold is cooled after the injection and the molten resin (P) in the cavity is cured to some extent, and then the mold is opened and the molded product is taken out. Since it is not necessary to prepare for the injection, it is possible to save time and effort.
[0034]
【The invention's effect】
As described above, according to the present invention, in the gas-assisted injection molding method, the amount of useless resin that is not used in a molded product can be greatly reduced, and material costs can be reduced and resources can be effectively used. Further, since the amount of resin that needs to be newly replenished for the next injection may be small, the molding cycle can be accelerated and the production efficiency is improved.
[Brief description of the drawings]
FIG. 1 is a view for explaining a gas assist injection molding method of the present invention.
FIG. 2 is a view for explaining a conventional gas-assisted injection molding method.
[Explanation of symbols]
(1) Mold (2) Cavity (3) Gas inlet (5) Gas supply device (20) Injection unit (21) Screw (22) Heating cylinder (P) Molten resin

Claims (3)

射出ユニットのスクリュにより金型のキャビティに溶融樹脂を射出した後に、該キャビティにガスを送り込み、キャビティ内のガスの圧力によりキャビティ内の溶融樹脂を射出ユニットに逆流させ、逆流した樹脂の圧力によって射出ユニットのスクリュを後退させ、スクリュの後退制御はスクリュの背圧を制御することにより行うことを特徴とするガスアシスト射出成形法。After injecting the molten resin into the mold cavity with the screw of the injection unit, gas is sent into the cavity, and the molten resin in the cavity is caused to flow back to the injection unit by the pressure of the gas in the cavity, and injection is performed by the pressure of the backflowed resin A gas-assisted injection molding method , wherein the screw of the unit is retracted, and the screw retraction is controlled by controlling the back pressure of the screw . 射出ユニットのスクリュにより金型のキャビティに溶融樹脂を射出した後に、該キャビティにガスを送り込み、キャビティ内のガスの圧力によりキャビティ内の溶融樹脂を射出ユニットに逆流させ、ガスの送り込み量に応じて射出ユニットのスクリュを後退させ、スクリュの後退制御は後退位置あるいは後退速度を制御することにより行うことを特徴とするガスアシスト射出成形法。 After injecting the molten resin into the mold cavity with the screw of the injection unit, gas is sent into the cavity, and the molten resin in the cavity is caused to flow back to the injection unit by the pressure of the gas in the cavity, and according to the amount of gas supplied A gas assist injection molding method , wherein the screw of the injection unit is moved backward, and the screw backward control is performed by controlling the backward position or the backward speed . 金型にはキャビティに連通するガス導入口が備えられており、ガス導入口には加圧されたガスをキャビティに送り込むためのガス供給装置が接続されており、射出ユニットにはスクリュの前進,後退を司る射出用サーボモータが備えられており、ガス供給装置とガス導入口との間にはガス流入計が設けられており、ガス流入計により測定されたガスの充填量に対応して射出ユニットのスクリュを所定の位置まで後退させるように射出用サーボモータを制御することを特徴とするガスアシスト射出成形装置。The mold is provided with a gas introduction port communicating with the cavity, and a gas supply device for sending pressurized gas into the cavity is connected to the gas introduction port . There is an injection servomotor that controls the retraction, and a gas inflow meter is provided between the gas supply device and the gas inlet, and injection is performed according to the gas filling amount measured by the gas inflow meter. A gas assist injection molding apparatus that controls an injection servomotor so that a screw of a unit is retracted to a predetermined position .
JP4105098A 1998-02-06 1998-02-06 Gas assist injection molding method and gas assist injection molding apparatus Expired - Fee Related JP3615650B2 (en)

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Application Number Priority Date Filing Date Title
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Publication number Priority date Publication date Assignee Title
TW548173B (en) * 2001-07-10 2003-08-21 Cinpres Gas Injection Ltd Process and apparatus for injection moulding a hollow plastics article
US6576170B1 (en) * 2002-04-23 2003-06-10 Bulk Molding Compounds, Inc. Gas-assisted injection molding of thermosetting polymers
CN103434083A (en) * 2013-09-04 2013-12-11 上海宝鹿车业有限公司 Air-assisting counter blowing process for handle and handle main body employing same

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