JPH10337757A - Method for injection molding - Google Patents

Method for injection molding

Info

Publication number
JPH10337757A
JPH10337757A JP15200097A JP15200097A JPH10337757A JP H10337757 A JPH10337757 A JP H10337757A JP 15200097 A JP15200097 A JP 15200097A JP 15200097 A JP15200097 A JP 15200097A JP H10337757 A JPH10337757 A JP H10337757A
Authority
JP
Japan
Prior art keywords
mold
resin
injection
screw
molten resin
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
Application number
JP15200097A
Other languages
Japanese (ja)
Inventor
Etsuo Okahara
悦雄 岡原
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ube Corp
Original Assignee
Ube Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Ube Industries Ltd filed Critical Ube Industries Ltd
Priority to JP15200097A priority Critical patent/JPH10337757A/en
Publication of JPH10337757A publication Critical patent/JPH10337757A/en
Pending legal-status Critical Current

Links

Landscapes

  • Moulds For Moulding Plastics Or The Like (AREA)
  • Injection Moulding Of Plastics Or The Like (AREA)

Abstract

PROBLEM TO BE SOLVED: To supplement a volume reduction of resin in the case of cooling melted resin by lowering resin pressure in a mold cavity, cooling to solidify the melted resin near a mold splitting surface of the mold to form a skin layer on a surface, and then again loading a forwarding force to an injection screw. SOLUTION: In the dwelling step, a set time for giving a forwarding force to a screw 34 is set by a timer, then the force of the screw 34 is removed, a mold clamping force is released, and the a cooling step is started while retaining in the mold closing state. In the dwelling step, melted resin charged in a mold cavity 5 is proceeded in cooling as a time is elapsed, a skin layer is formed on a contact surface with the mold, and simultaneously volume reduction occurs in the case of cooling to solidify it. A skin layer of sufficient thickness is formed at resin in contact with a gap provided at parting surfaces, and a forwarding force is again loaded to the screw 34. The resin compressed by the force of the screw 34 flows into the cavity 5 to compensate for the volume reduction due to the cooling of the resin.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、射出成形方法に係
り、特に、金型キャビティの容積に見合う溶融樹脂を射
出完了後、前記射出スクリュに負荷する前進力を、一
旦、低下あるいは除去して該金型キャビティ内樹脂圧力
を低下させ、該金型の金型割り面近傍の溶融樹脂が冷却
固化して表面にスキン層を形成せしめてから、再度、該
射出スクリュに前進力を負荷させて、溶融樹脂の冷却に
伴なう樹脂の体積減少を補い成形品を得る射出成形方法
関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method, and more particularly, to a method in which after a molten resin corresponding to a volume of a mold cavity is completely injected, a forward force applied to the injection screw is once reduced or removed. After lowering the resin pressure in the mold cavity, the molten resin in the vicinity of the mold split surface of the mold is cooled and solidified to form a skin layer on the surface, and then a forward force is again applied to the injection screw. The present invention relates to an injection molding method for obtaining a molded product by compensating for a decrease in the volume of a resin accompanying cooling of a molten resin.

【0002】[0002]

【従来の技術】従来の射出成形においては、溶融樹脂の
射出充填に伴い、金型内の空気や溶融樹脂から発生する
ガスを圧縮しながら充填が進行するが、この圧縮ガスの
圧力に打ち克って充填を続行しようとすると高い射出圧
力が必要となり、この結果、金型内の樹脂圧力は高くな
り、ポリプロピレン樹脂の場合で0.03mm以上の隙
間、ナイロン樹脂の場合では0.01mm以上の隙間が
あると、この隙間から溶融樹脂が外部へ吹き出してバリ
発生の原因となると言われており、金型が開かないよう
にするために、大きい型締力を必要としていた。しかも
この高い樹脂圧力が内部応力の原因となり、高圧の金型
キャビティより型開して取り出した製品に応力開放によ
るソリが発生する等の問題があった。このため、金型割
り面にガス抜き機能を付与した金型が使用されることが
試みられたが、バリの発生を完全に防止することが困難
であった。
2. Description of the Related Art In conventional injection molding, the filling proceeds while compressing air in a mold and gas generated from the molten resin with injection filling of a molten resin. In order to continue filling, a high injection pressure is required, and as a result, the resin pressure in the mold increases, and a gap of 0.03 mm or more in the case of polypropylene resin and 0.01 mm or more in the case of nylon resin. It is said that if there is a gap, the molten resin blows out from the gap to cause burrs, and a large mold clamping force is required to prevent the mold from opening. In addition, the high resin pressure causes internal stress, and there is a problem that a product released from the high-pressure mold cavity and taken out is warped due to the release of stress. For this reason, attempts have been made to use a mold having a degassing function on the mold split surface, but it has been difficult to completely prevent the occurrence of burrs.

【0003】これらの問題を解決するために、低圧射出
技術が提案されている。低圧射出技術としては、射出圧
縮成形や射出プレス成形と呼ばれる、金型を僅かに開い
て射出し、射出充填完了後に金型を閉じる技術がよく知
られている。
In order to solve these problems, a low-pressure injection technique has been proposed. As a low-pressure injection technique, a technique called injection compression molding or injection press molding, in which a mold is slightly opened to perform injection, and the mold is closed after completion of injection filling, is well known.

【0004】[0004]

【発明が解決しようとする課題】このような射出圧縮成
形や射出プレス成形においては、金型を開いたときの樹
脂漏れを防止するため、喰い切り構造を有する金型を使
用する必要がある。この喰い切り構造を有する金型は、
通常の割り面をもった金型に比べて耐久性の面で劣り、
しかも、金型コストが高くなるという問題があった。一
方、特開平7−100883号公報には、通常の割り面
をもった金型を使用して型締力を低圧化して、バリやヒ
ケ、ソリ等の発生を防止する技術が開示されているが、
装置の制御が複雑になり、射出成形機の製造コストが高
くなるという問題があった。
In such injection compression molding and injection press molding, it is necessary to use a mold having a biting structure in order to prevent resin leakage when the mold is opened. A mold having this bite structure
Inferior in durability compared to a mold with a normal split surface,
In addition, there is a problem that the mold cost is increased. On the other hand, Japanese Patent Application Laid-Open No. 7-100883 discloses a technique of using a mold having a normal split surface to lower the mold clamping force to prevent generation of burrs, sink marks, warpage, and the like. But,
There is a problem that the control of the apparatus becomes complicated and the manufacturing cost of the injection molding machine increases.

【0005】本発明は、これら上述の従来技術の問題を
解決して、通常の割り面をもった金型を使用し、特別に
高価な制御機能をもたない射出成形機を使用して、射出
時における金型キャビティ内のガス、および、射出充填
される樹脂から発生するガスを金型割り面に設けた隙間
から効率よく排出することにより、射出圧力の低圧化、
ひいては、金型キャビティ内樹脂圧の低圧化を達成する
と同時に、バリやヒケ、ソリ等の欠陥の無い良好な品質
の成形品を、簡便容易に、しかも、低コストで成形する
ことを意図している。
The present invention solves the above-mentioned problems of the prior art, and uses a mold having a normal split surface and an injection molding machine having no special expensive control function. The gas in the mold cavity at the time of injection, and the gas generated from the resin to be injected and filled are efficiently exhausted from the gaps provided on the mold split surface, thereby lowering the injection pressure.
Consequently, at the same time as achieving a reduction in the resin pressure in the mold cavity, it is intended to mold a good quality molded product without defects such as burrs, sink marks and warpage simply and easily and at low cost. I have.

【0006】[0006]

【課題を解決するための手段】以上のような課題を解決
するために、本発明においては、第1の発明では、射出
成形機の射出スクリュを前進させて、対向する左右一対
または上下一対の金型の間の金型キャビティ内に溶融樹
脂を射出充填する射出成形方法において、溶融樹脂の充
填完了直前の流動先端位置が金型割り面になるようにゲ
ート配置を施すとともに、該両金型の完全型閉時に該流
動先端位置となる金型割り面の全面もしくは一部に金型
キャビティ内のガスを排出する隙間を設け、該両金型を
型閉し、金型キャビティの容積に見合う溶融樹脂を射出
完了した後、前記射出スクリュに負荷する前進力を、一
旦、低下あるいは除去して該金型キャビティ内樹脂圧力
を低下させ、該金型の金型割り面近傍の溶融樹脂が冷却
固化して表面にスキン層を形成せしめてから、再度、該
射出スクリュに前進力を負荷させて、溶融樹脂の冷却に
伴なう樹脂の体積減少を補い成形品を得ることとした。
In order to solve the above-mentioned problems, in the first invention, in the first invention, an injection screw of an injection molding machine is moved forward so that a pair of opposed left and right or upper and lower pairs is formed. In an injection molding method for injecting and filling a molten resin into a mold cavity between molds, a gate arrangement is performed so that a flow front position immediately before completion of filling of the molten resin is a mold splitting surface, and both molds are provided. When the mold is completely closed, a gap for discharging the gas in the mold cavity is provided on the entire surface or a part of the mold splitting surface which is the flow front position, and the molds are closed to match the volume of the mold cavity. After the injection of the molten resin is completed, the forward force applied to the injection screw is temporarily reduced or removed to reduce the resin pressure in the mold cavity, and the molten resin in the vicinity of the mold split surface of the mold is cooled. Solidifies on the surface After allowed forming a down layer, again by loading the advancing force to the injection-screw, it was to obtain a molded article compensate the reduction in volume accompanying the resin to cool the molten resin.

【0007】また、第2の発明では、第1の発明におけ
る隙間を、厚さが0.01mm〜0.3mmとした。
In the second invention, the gap in the first invention has a thickness of 0.01 mm to 0.3 mm.

【0008】[0008]

【発明の実施の形態】本発明においては、第1の発明で
は、射出成形機の射出スクリュを前進させて、対向する
左右一対または上下一対の金型の間の金型キャビティ内
に溶融樹脂を射出充填する射出成形方法において、溶融
樹脂の充填完了直前の流動先端位置が金型割り面になる
ようにゲート配置を施すとともに、該両金型の完全型閉
時に該流動先端位置となる金型割り面の全面もしくは一
部に金型キャビティ内のガスを排出する隙間を設け、該
両金型を型閉し、金型キャビティの容積に見合う溶融樹
脂を射出完了した後、前記射出スクリュに負荷する前進
力を、一旦、低下あるいは除去して該金型キャビティ内
樹脂圧力を低下させ、該金型の金型割り面近傍の溶融樹
脂が冷却固化して表面にスキン層を形成せしめてから、
再度、該射出スクリュに前進力を負荷させて、溶融樹脂
の冷却に伴なう樹脂の体積減少を補い成形品を得ること
としたため、金型キャビティ内のガスや溶融樹脂から発
生したガスは、溶融樹脂の射出充填の進行とともに圧縮
されるが、この圧力の上昇とともに金型割り面の隙間か
ら外部に抜けて、従来技術の金型が完全に型締されて閉
塞された状態のように高圧状態に圧縮されることがない
から、金型キャビティ内の樹脂圧を比較的低い状態にし
て再度溶融樹脂の射出充填が可能となり、低い射出力で
射出出来て、結果的に小さい型締力で成形が可能とな
る。その結果、バリやヒケ、ソリ等の欠陥の無い良好な
品質の成形品を、簡便容易に、しかも、低コストで成形
することが出来る。
BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, in the first invention, an injection screw of an injection molding machine is advanced, and molten resin is injected into a mold cavity between a pair of opposed left and right or upper and lower molds. In the injection molding method for injection filling, the gate is arranged so that the flow front position immediately before the completion of the filling of the molten resin is the mold splitting surface, and the mold which becomes the flow front position when the two dies are completely closed. A gap for discharging gas in the mold cavity is provided on the entire or part of the split surface, the molds are closed, and after the molten resin corresponding to the volume of the mold cavity is completely injected, a load is applied to the injection screw. The advancing force, once reduced or removed to reduce the resin pressure in the mold cavity, the molten resin near the mold split surface of the mold is cooled and solidified to form a skin layer on the surface,
Again, a forward force is applied to the injection screw to compensate for the decrease in resin volume accompanying cooling of the molten resin to obtain a molded product.Therefore, gas in the mold cavity and gas generated from the molten resin are: It is compressed with the progress of injection filling of the molten resin. Since it is not compressed into a state, the resin pressure in the mold cavity can be made relatively low and injection filling of the molten resin can be performed again, and it can be injected with a low injection power, resulting in a small mold clamping force. Molding becomes possible. As a result, a molded product of good quality without defects such as burrs, sink marks and warpage can be molded simply and easily at a low cost.

【0009】また、第2の発明では、隙間の厚さを0.
01mm〜0.3mmとしたため、初期射出充填中は、
金型キャビティ内のガスが容易に外部に排出されると同
時に、初期射出充填が完了した後には、金型キャビティ
内の溶融樹脂の外部への漏出が防止され、バリ発生とヒ
ケの生成を抑止することが可能となる。
Further, in the second invention, the thickness of the gap is set to 0.1.
Because it was set to 01 mm to 0.3 mm, during the initial injection filling,
The gas in the mold cavity is easily discharged to the outside, and at the same time after the initial injection filling is completed, the leakage of the molten resin in the mold cavity to the outside is prevented, preventing the generation of burrs and sink marks. It is possible to do.

【0010】[0010]

【実施例】以下図面に基づいて本発明の実施例の詳細に
ついて説明する。図1〜図7は本発明の実施例に係り、
図1は本発明に使用する射出成形機の全体構成図、図2
は充填完了直前における金型の要部縦断面図、図3は図
2のA−A視の平面図、図4は図3の金型の金型キャビ
ティへ射出充填される溶融樹脂の進行推移を説明する正
面図、図5は他の実施例を示す充填完了直前における金
型の要部縦断面図、図6は図5の金型の金型キャビティ
へ射出充填される溶融樹脂の進行推移を説明する正面
図、図7は射出成形工程のフローチャートである。
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 7 relate to an embodiment of the present invention,
FIG. 1 is an overall configuration diagram of an injection molding machine used in the present invention, and FIG.
3 is a longitudinal sectional view of a main part of the mold immediately before completion of filling, FIG. 3 is a plan view taken along the line AA of FIG. 2, and FIG. 4 is a progression of molten resin injected and filled into the mold cavity of the mold of FIG. FIG. 5 is a vertical sectional view of a main part of a mold immediately before completion of filling, showing another embodiment, and FIG. 6 is a progress transition of molten resin injected and filled into a mold cavity of the mold of FIG. FIG. 7 is a flowchart of the injection molding process.

【0011】図1に示すように、本発明における射出成
形機100は、金型装置10と型締装置20と射出装置
30と制御装置60とで構成される。金型装置10は、
固定盤1に取り付けられた固定金型3と可動盤2に取り
付けられた可動金型4とからなり、可動盤2および可動
金型4は型締装置20の型締シリンダ22で前後進でき
るよう構成される。型締装置20は、金型装置10の両
金型3、4の型開、型閉を作動する型締シリンダ22を
備えており、可動金型4が固定金型3に対して図示しな
いタイバーに案内されて前後進する。
As shown in FIG. 1, an injection molding machine 100 according to the present invention comprises a mold device 10, a mold clamping device 20, an injection device 30, and a control device 60. The mold apparatus 10
It comprises a fixed mold 3 attached to the fixed platen 1 and a movable mold 4 attached to the movable platen 2. The movable platen 2 and the movable mold 4 can be moved forward and backward by the mold clamping cylinder 22 of the mold clamping device 20. Be composed. The mold clamping device 20 includes a mold clamping cylinder 22 that operates to open and close the molds 3 and 4 of the mold device 10. The movable mold 4 is connected to the fixed mold 3 by a tie bar (not shown). You will be guided back and forth.

【0012】射出装置30は、バレル32内に外周にス
パイラル状に取り付けられたスクリュ羽根36を備えた
スクリュ34が、正逆転油圧モータ42および射出シリ
ンダ40により回転自在で、かつ前後進自在に配設さ
れ、ホッパ38に供給された樹脂ペレットを加熱溶融し
て混練しつつノズル39を経由して、金型3、4間に形
成される金型キャビティ5内へ溶融樹脂を射出する。す
なわち、射出装置30は、ホッパ38内の樹脂原料をバ
レル32内の供給ゾーン、圧縮ゾーンにおいて加熱圧縮
し、計量ゾーンにおいて溶融計量し、射出ゾーンを経て
ノズル39の樹脂流路39a、ランナ3a、ゲート3b
を介して金型キャビティ5内へ射出するよう構成され
る。射出シリンダ40および正逆転油圧モータ42に
は、油圧供給源50により供給される作動油が射出制御
部61の操作指令を受けた油圧制御弁52で設定された
一定の圧力で供給され、駆動される。
The injection device 30 includes a screw 32 provided with a screw blade 36 spirally mounted on the outer periphery of a barrel 32. The screw 34 is rotatable by a forward / reverse hydraulic motor 42 and an injection cylinder 40, and is freely rotatable forward and backward. The molten resin is injected into the mold cavity 5 formed between the molds 3 and 4 via the nozzle 39 while heating and melting and kneading the resin pellets supplied to the hopper 38. That is, the injection device 30 heats and compresses the resin raw material in the hopper 38 in the supply zone and the compression zone in the barrel 32, melts and measures in the measurement zone, passes through the injection zone, the resin flow path 39 a of the nozzle 39, the runner 3 a, Gate 3b
Through the mold cavity 5. Hydraulic oil supplied from a hydraulic supply source 50 is supplied to the injection cylinder 40 and the forward / reverse rotation hydraulic motor 42 at a constant pressure set by a hydraulic control valve 52 that has received an operation command from an injection control unit 61, and is driven. You.

【0013】一方、制御装置60は、図1に示すよう
に、固定金型3に配置された樹脂圧センサ63で計測さ
れた圧力情報と温度センサ65で計測されたコア材樹脂
温度情報とを入力し型締装置20の型締シリンダ22に
油圧制御弁69を経由して操作信号を与える型締制御部
62と、型締制御部62に接続されたタイマ66と、型
締制御部62に接続された射出制御部61とで構成され
る。70は油圧供給源である。
On the other hand, as shown in FIG. 1, the control device 60 converts the pressure information measured by the resin pressure sensor 63 disposed on the fixed mold 3 and the core material resin temperature information measured by the temperature sensor 65. A mold clamping control unit 62 that inputs and provides an operation signal to the mold clamping cylinder 22 of the mold clamping device 20 via a hydraulic control valve 69, a timer 66 connected to the mold clamping control unit 62, and a mold clamping control unit 62 It is composed of an injection control unit 61 connected thereto. 70 is a hydraulic supply source.

【0014】なお、本実施例では、直圧式の型締装置を
有する射出成形機を用いたが、トグル型締装置の射出成
形機や、あるいは竪型の射出成形機または電動式の型締
装置を有する射出成形機を使用してもよい。
In this embodiment, an injection molding machine having a direct pressure type mold clamping device is used. However, an injection molding machine of a toggle mold clamping device, a vertical injection molding machine, or an electric type mold clamping device is used. May be used.

【0015】図2は本発明の充填完了直前における金型
の要部縦断面図を示したもので、本発明においては、溶
融樹脂の充填完了直前の流動先端位置が金型割り面にな
るようにゲート配置を施す(逆に言うと、ゲート3bか
ら供給された溶融樹脂が金型割り面に到達した後、反転
して金型キャビティ5の中央部に向かわないようなゲー
ト配置を採る)とともに、該両金型3、4の完全型閉時
に該流動先端位置となる金型割り面の全面もしくは一部
に金型キャビティ5内のガスを排出する隙間Sを設け
る。すなわち、図2の実施例では、金型キャビティ5と
ノズル39の樹脂流路39aとは1本のゲート3b(こ
の実施例では、ゲート3bがランナ3aを兼ねている)
で接続され、両金型(固定金型3および可動金型4)が
型締された完全型閉時においても、固定金型4に設けた
ゲート3bから金型キャビティ5内へ射出充填される溶
融樹脂の先端部が金型割り面に到達した状態で射出充填
が完了するようなゲート配置を行ない、かつ、図3の平
面図からも判るように、完全型閉状態でも割り面の全面
もしくは一部に隙間Sが出来るような金型の組合せを構
成して、射出中のガスの排出を円滑に進行させる。
FIG. 2 is a longitudinal sectional view of a main part of the mold immediately before the completion of filling according to the present invention. In the present invention, the flow front position immediately before the completion of filling of the molten resin is the mold dividing surface. (Conversely, after the molten resin supplied from the gate 3b reaches the mold split surface, the gate is reversed so as not to go to the center of the mold cavity 5.) When the molds 3 and 4 are completely closed, a gap S for discharging gas in the mold cavity 5 is provided on the entire surface or a part of the mold splitting surface which is the flow front position. In other words, in the embodiment of FIG. 2, the mold cavity 5 and the resin flow path 39a of the nozzle 39 are provided with one gate 3b (in this embodiment, the gate 3b also serves as the runner 3a).
Even when the two molds (the fixed mold 3 and the movable mold 4) are closed, the mold is injected and filled into the mold cavity 5 from the gate 3b provided in the fixed mold 4. The gate is arranged so that the injection filling is completed when the tip of the molten resin reaches the mold splitting surface, and as can be seen from the plan view of FIG. A combination of dies that partially forms the gap S is configured to smoothly discharge the gas during the injection.

【0016】図3は、図2の金型における金型キャビテ
ィ5へ射出充填される溶融樹脂の進行推移を説明する正
面図を示し、溶融樹脂の流動先端位置が金型割り面にな
るようにゲート配置を施すとともに、該両金型3、4の
完全型閉時に該流動先端位置となる金型割り面の全面も
しくは一部に金型キャビティ5内のガスを排出する隙間
Sを設ける。すなわち、隙間Sを設ける位置は、図4
(c)の「射出完了直前」の状態で、未だ溶融樹脂の充
填されていない4点(図中、白い部分)の位置とするこ
とがガス抜きの観点から、望ましい。
FIG. 3 is a front view for explaining the progress of the molten resin injected and filled into the mold cavity 5 in the mold shown in FIG. 2 so that the flow front position of the molten resin becomes the mold splitting surface. A gate S is provided, and a gap S for discharging gas in the mold cavity 5 is provided on the entire surface or a part of the mold splitting surface which is the flow front position when the molds 3 and 4 are completely closed. That is, the position at which the gap S is provided is as shown in FIG.
From the viewpoint of degassing, it is desirable to set the positions of four points (white portions in the figure) not yet filled with the molten resin in the state "just before the completion of injection" of (c).

【0017】一方、図5は、金型キャビティ5に対して
ゲート3aを上下に2本水平に設けた実施例を示し、こ
の場合には、図6(c)に示すように、隙間Sを設ける
位置は、図示の未だ溶融樹脂の充填されていない6点
(図中、白い部分)を含むように設けることが望まし
い。
On the other hand, FIG. 5 shows an embodiment in which two gates 3a are provided vertically above and below the mold cavity 5, and in this case, as shown in FIG. It is desirable that the positions are provided so as to include six points (white portions in the figure) not yet filled with the molten resin.

【0018】このように、構成された射出成形機100
における本発明の射出成形方法について、説明する。図
7は、本発明における成形方法のフローチャートであ
り、図7に示す工程にしたがって操業する。
The injection molding machine 100 constructed as described above
The injection molding method of the present invention will be described. FIG. 7 is a flowchart of the molding method according to the present invention, and operates according to the steps shown in FIG.

【0019】(1)まず、金型装置10の両金型3、4
が型開された状態から、完全型開(この場合でも、隙間
Sを設けた位置では、金型キャビティ5は外部と連通状
態にある)し、所定の低圧の型締力で両金型3、4を型
締する。
(1) First, the two dies 3, 4 of the die apparatus 10
Is completely opened (in this case also, at the position where the gap S is provided, the mold cavity 5 is in communication with the outside), and the two molds 3 are pressed at a predetermined low pressure. 4. Clamp the mold.

【0020】(2)次に、溶融樹脂の射出充填を開始
し、射出装置30のスクリュ34に前進力を与えて、金
型キャビティ5の容積に見合う溶融樹脂量を射出する。
射出充填が、図3や図5に示したように推移し、射出充
填が完了すると、射出装置30のスクリュ34の前進力
を除去する。すなわち、本発明では、射出開始から射出
充填が進行し、金型キャビティ5へ溶融樹脂が充満する
までは、従来技術と同様に、スクリュ34に前進力を付
与しているが、金型キャビティ5内に溶融樹脂が過不足
無く充満した時点でスクリュ前進力を除去し、あるい
は、かぎりなく零に近い値に低下させ、隙間Sに連通す
る部分の金型キャビティ内樹脂の樹脂圧力が、ほぼ0k
gf/cm2 となるようにする。このような状態に保持
された、金型キャビティ5内に存在するガスは、隙間S
より金型外部に排出されるが、樹脂圧力が低いために、
従来技術でバリ発生の限界とされていた上限値よりも遙
かに大きな隙間Sであっても、溶融樹脂の隙間Sからの
漏出が無く、したがってバリ発生が防止される。このと
き、スクリュ先端部の樹脂は圧縮状態にあるため、スク
リュ34を押し戻す力がスクリュ34に働き、スクリュ
34は負荷させた前進力ととのバランス点まで僅かに後
退する。
(2) Next, injection filling of the molten resin is started, and a forward force is applied to the screw 34 of the injection device 30 to inject a molten resin amount corresponding to the volume of the mold cavity 5.
The injection filling changes as shown in FIG. 3 and FIG. 5, and when the injection filling is completed, the forward force of the screw 34 of the injection device 30 is removed. That is, in the present invention, the forward force is applied to the screw 34 in the same manner as in the related art until the injection filling proceeds from the start of injection to the time when the mold cavity 5 is filled with the molten resin. When the molten resin has been filled with no excess or shortage, the screw advancing force is removed or reduced to a value close to zero as much as possible, and the resin pressure of the resin in the mold cavity communicating with the gap S becomes almost 0 k
gf / cm 2 . The gas existing in the mold cavity 5 held in such a state is generated by the gap S
It is discharged outside the mold, but because the resin pressure is low,
Even if the gap S is much larger than the upper limit, which is considered to be the limit of burr generation in the prior art, there is no leakage of the molten resin from the gap S, and thus burr generation is prevented. At this time, since the resin at the tip of the screw is in a compressed state, a force for pushing back the screw 34 acts on the screw 34, and the screw 34 slightly retreats to a balance point with the applied forward force.

【0021】(3)この前進力を除去する設定時間t1
は、タイマで設定し、設定時間t1 の終了後は、保圧工
程に入り、再び、スクリュ34に前進力を付与する(こ
の保圧工程では、冷却に進行による金型キャビティ5内
の樹脂の収縮量を補うために、溶融樹脂を金型キャビテ
ィ5内へ補充する)。
(3) Set time t 1 for removing this forward force
Is set by a timer, and after the set time t 1 , the pressure-holding step is started, and the forward force is again applied to the screw 34 (in this pressure-holding step, the resin in the mold cavity 5 due to the progress of the cooling is cooled). The molten resin is replenished into the mold cavity 5 in order to compensate for the shrinkage of the mold.

【0022】(4)この保圧工程の、スクリュ34に前
進力を付与する設定時間t2 もタイマで設定し、設定時
間t2 の終了後に、スクリュの前進力を除去し、つい
で、型締力を解除して、型閉状態のまま冷却工程に入
る。この保圧工程では、金型キャビティ5内へ充填され
た溶融樹脂は、経過時間とともに冷却が進行し、金型と
の接触面には、「スキン層」と呼ばれる固化層が生成す
ると同時に、前述したように、冷却固化に伴なう体積減
少が起こるから、パーティング面(金型割り面)に設け
た隙間Sに接触する樹脂に十分な厚さのスキン層を形成
せしめてから、再度、スクリュ34に前進力を負荷す
る。スクリュの前進力により圧縮された樹脂が金型キャ
ビティ内に流入し、既に充填されていた樹脂の冷却に起
因する体積減少分を補填する。 (5)冷却工程が完了すると、型開して、成形品を製品
として取り出す。
(4) The set time t 2 for applying the forward force to the screw 34 in this pressure holding step is also set by a timer, and after the set time t 2 , the forward force of the screw is removed. Release the force and enter the cooling process with the mold closed. In this pressure-holding step, the molten resin filled in the mold cavity 5 cools down with the lapse of time, and a solidified layer called a “skin layer” is formed on the contact surface with the mold, and at the same time as described above. As described above, since the volume decreases due to cooling and solidification, a sufficiently thick skin layer is formed on the resin that comes into contact with the gap S provided on the parting surface (the mold split surface), and then, again, A forward force is applied to the screw 34. The resin compressed by the advancing force of the screw flows into the mold cavity, and compensates for the volume decrease due to cooling of the resin already filled. (5) When the cooling step is completed, the mold is opened and the molded product is taken out as a product.

【0023】以上述べた一連の成形工程において、本発
明では、射出中は、溶融樹脂の金型キャビティ内への射
出充填により、金型キャビティ内の空気や溶融樹脂から
発生するガスが隙間Sから抜け、金型キャビティが完全
型閉されて外部と閉塞されて、従来技術の状態のように
溶融樹脂が高圧に圧縮されることはない。したがって、
金型キャビティ内の樹脂圧も低い状態で充填が可能とな
り、低い射出力で射出することが出来て、結果的に小さ
い型締力で成形が可能となる。
In the above-described series of molding steps, according to the present invention, during injection, the molten resin is injected into the mold cavity, so that air in the mold cavity or gas generated from the molten resin flows from the gap S. As a result, the mold cavity is completely closed and closed with the outside, so that the molten resin is not compressed to a high pressure unlike the state of the prior art. Therefore,
Filling can be performed in a state where the resin pressure in the mold cavity is also low, and injection can be performed with a low injection power. As a result, molding can be performed with a small mold clamping force.

【0024】射出が進行して、金型割り面の隙間Sに溶
融樹脂の流動先端部が到達し、初期充填が終了した時点
でスクリュ前進力が除去または低下されるため、金型キ
ャビティ内樹脂圧力も低下し、ガス抜き用の隙間Sが
0.3mm以下であるならば、この隙間Sに溶融樹脂が
入り込んで、いわゆる、バリ発生を起こすことも無い。
さらに、樹脂の冷却固化に伴なうスキン層が生成した後
に、再度、スクリュ前進力を付与しているので、バリの
発生を防止しつつヒケの発生も防止できる。
The injection progresses, the leading end of the molten resin reaches the gap S on the mold split surface, and when the initial filling is completed, the screw advancing force is removed or reduced. If the pressure also decreases and the gap S for degassing is 0.3 mm or less, the molten resin does not enter the gap S and so-called burrs do not occur.
Furthermore, since the screw advancing force is applied again after the formation of the skin layer accompanying the cooling and solidification of the resin, the occurrence of burrs can be prevented while preventing the generation of burrs.

【0025】次に、第2発明の隙間Sの数値限定理由に
ついて、説明する。隙間Sの厚さは、0.01mm〜
0.3mmとしたが、隙間Sを0.01mm以下にする
と金型キャビティ無いの空気や溶融樹脂から発生するガ
スの排出抵抗が増えてガス抜きが不十分になる惧れがあ
り、また、逆に、0.3mm以上にすると隙間S内に溶
融樹脂が入り込んで、バリ発生を起こしてしまう。な
お、本発明の出願人の種々のテスト結果によれば、たと
えば、ナイロン樹脂のような粘度が低く、バリ発生の惧
れが強い樹脂の場合には、隙間Sの選定範囲は、0.0
1mm〜0.2mmとすることが望ましく、また、たと
えば、ポリプロピレン樹脂のような比較的粘度が高く、
バリ発生のしにくい樹脂の場合には、隙間Sの選定範囲
は、0.03mm〜0.3mmとすることが望ましいこ
とが判った。
Next, the reason for limiting the numerical value of the gap S according to the second invention will be described. The thickness of the gap S is from 0.01 mm
The gap S is set to 0.3 mm, but if the gap S is set to 0.01 mm or less, there is a possibility that the gas generated from the air or the molten resin without the mold cavity may have an increased resistance to discharge, resulting in insufficient degassing. On the other hand, if the thickness is 0.3 mm or more, the molten resin enters the gap S, causing burrs. According to various test results of the applicant of the present invention, for example, in the case of a resin such as a nylon resin having a low viscosity and a strong possibility of generating burrs, the selection range of the gap S is 0.0
1 mm to 0.2 mm is desirable, and, for example, relatively high viscosity such as polypropylene resin,
In the case of a resin that does not easily generate burrs, it has been found that the selection range of the gap S is desirably 0.03 mm to 0.3 mm.

【0026】[0026]

【発明の効果】以上述べたように、本発明の方法によれ
ば、簡便容易な構造や手順により、金型キャビティ内の
樹脂圧力を低圧で成形が可能となり、バリ、ヒケ、ソリ
等の無い良好な成形品を安定、連続的に低コストで得る
ことが出来る。
As described above, according to the method of the present invention, the resin pressure in the mold cavity can be molded at a low pressure by a simple and easy structure and procedure, and there are no burrs, sink marks, warpage, etc. Good molded products can be obtained stably and continuously at low cost.

【図面の簡単な説明】[Brief description of the drawings]

【図1】本発明の実施例に係る射出成形機の全体構成図
である。
FIG. 1 is an overall configuration diagram of an injection molding machine according to an embodiment of the present invention.

【図2】本発明の実施例に係る充填完了直前における金
型の要部縦断面図である。
FIG. 2 is a longitudinal sectional view of a main part of a mold immediately before completion of filling according to an embodiment of the present invention.

【図3】図2のA−A視の平面図である。FIG. 3 is a plan view taken along line AA of FIG. 2;

【図4】図2の金型の金型キャビティへ射出充填される
溶融樹脂の進行推移を説明する正面図である。
FIG. 4 is a front view for explaining the progress of molten resin injected and filled into a mold cavity of the mold of FIG. 2;

【図5】本発明の実施例に係る充填完了直前における金
型の要部縦断面図である。
FIG. 5 is a vertical sectional view of a main part of a mold immediately before completion of filling according to the embodiment of the present invention.

【図6】図5の金型の金型キャビティへ射出充填される
溶融樹脂の進行推移を説明する正面図である。
6 is a front view for explaining the progress of molten resin injected and filled into a mold cavity of the mold of FIG. 5;

【図7】本発明の実施例に係る射出成形工程のフローチ
ャートである。
FIG. 7 is a flowchart of an injection molding process according to an embodiment of the present invention.

【符号の説明】[Explanation of symbols]

1 固定盤 2 可動盤 3 固定金型 3a ランナ 3b ゲート 4 可動金型 5 金型キャビティ 10 金型装置 20 型締装置 22 型締シリンダ 30 射出装置 32 バレル 34 スクリュ 36 スクリュ羽根 38 ホッパ 39 ノズル 39a 樹脂流路 40 射出シリンダ 42 油圧モータ 50 油圧供給源 52 油圧制御弁 60 制御装置 61 射出制御部 62 型締制御部 63 樹脂圧センサ 65 温度センサ 66 タイマ 69 油圧制御弁 70 油圧供給源 100 射出成形機 S 隙間 DESCRIPTION OF SYMBOLS 1 Fixed board 2 Movable board 3 Fixed mold 3a Runner 3b Gate 4 Movable mold 5 Mold cavity 10 Mold device 20 Mold clamping device 22 Mold clamping cylinder 30 Injection device 32 Barrel 34 Screw 36 Screw blade 38 Hopper 39 Nozzle 39a Resin Flow path 40 Injection cylinder 42 Hydraulic motor 50 Hydraulic supply source 52 Hydraulic control valve 60 Control device 61 Injection control unit 62 Mold clamping control unit 63 Resin pressure sensor 65 Temperature sensor 66 Timer 69 Hydraulic control valve 70 Hydraulic supply source 100 Injection molding machine S Gap

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】 射出成形機の射出スクリュを前進させ
て、対向する左右一対または上下一対の金型の間の金型
キャビティ内に溶融樹脂を射出充填する射出成形方法に
おいて、 溶融樹脂の充填完了直前の流動先端位置が金型割り面に
なるようにゲート配置を施すとともに、該両金型の完全
型閉時に該流動先端位置となる金型割り面の全面もしく
は一部に金型キャビティ内のガスを排出する隙間を設
け、 該両金型を型閉し、金型キャビティの容積に見合う溶融
樹脂を射出完了した後、前記射出スクリュに負荷する前
進力を、一旦、低下あるいは除去して該金型キャビティ
内樹脂圧力を低下させ、該金型の金型割り面近傍の溶融
樹脂が冷却固化して表面にスキン層を形成せしめてか
ら、再度、該射出スクリュに前進力を負荷させて、溶融
樹脂の冷却に伴なう樹脂の体積減少を補い成形品を得る
ことを特徴とする射出成形方法。
1. An injection molding method for advancing an injection screw of an injection molding machine and injecting and filling a molten resin into a mold cavity between a pair of left and right or upper and lower opposed molds. The gate arrangement is performed so that the flow front position immediately before is the mold splitting surface, and the entire surface or a part of the mold splitting surface that becomes the flow front position when the two dies are completely closed is a mold cavity. After providing a gap for discharging gas, closing both the molds and injecting the molten resin corresponding to the volume of the mold cavity, the forward force applied to the injection screw is once reduced or removed to temporarily reduce or remove the forward force. Lowering the resin pressure in the mold cavity, the molten resin near the mold split surface of the mold is cooled and solidified to form a skin layer on the surface, and then again, applying a forward force to the injection screw, Cooling of molten resin Injection molding method characterized by obtaining compensate the molded product volume decreased accompanied resin.
【請求項2】 厚さが0.01mm〜0.3mmの隙間
を設けた請求項1記載の射出成形方法。
2. The injection molding method according to claim 1, wherein a gap having a thickness of 0.01 mm to 0.3 mm is provided.
JP15200097A 1997-06-10 1997-06-10 Method for injection molding Pending JPH10337757A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP15200097A JPH10337757A (en) 1997-06-10 1997-06-10 Method for injection molding

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP15200097A JPH10337757A (en) 1997-06-10 1997-06-10 Method for injection molding

Publications (1)

Publication Number Publication Date
JPH10337757A true JPH10337757A (en) 1998-12-22

Family

ID=15530885

Family Applications (1)

Application Number Title Priority Date Filing Date
JP15200097A Pending JPH10337757A (en) 1997-06-10 1997-06-10 Method for injection molding

Country Status (1)

Country Link
JP (1) JPH10337757A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003053798A (en) * 2001-08-09 2003-02-26 Fuji Photo Film Co Ltd Mold for injection molding and method for injection molding
JP2014177131A (en) * 2010-06-25 2014-09-25 Nissei Plastics Ind Co Molding method for injection molding machine

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003053798A (en) * 2001-08-09 2003-02-26 Fuji Photo Film Co Ltd Mold for injection molding and method for injection molding
JP2014177131A (en) * 2010-06-25 2014-09-25 Nissei Plastics Ind Co Molding method for injection molding machine

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