JP2587900B2 - Plastic injection molded products and their molds - Google Patents
Plastic injection molded products and their moldsInfo
- Publication number
- JP2587900B2 JP2587900B2 JP5205841A JP20584193A JP2587900B2 JP 2587900 B2 JP2587900 B2 JP 2587900B2 JP 5205841 A JP5205841 A JP 5205841A JP 20584193 A JP20584193 A JP 20584193A JP 2587900 B2 JP2587900 B2 JP 2587900B2
- Authority
- JP
- Japan
- Prior art keywords
- plastic
- molding
- mold
- cavity
- injection
- 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.)
- Expired - Fee Related
Links
Landscapes
- Moulds For Moulding Plastics Or The Like (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Description
【0001】[0001]
【産業上の利用分野】本発明は、一度の射出成形によ
り、表面にひけや変形が生せず、高精度に成形されたプ
ラスチックの射出成形品と、この射出成形品を複数同時
に成形できるようにした成形用金型に関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic injection molded article which is molded with high precision without causing sink marks and deformations by one injection molding, and a plurality of such injection molded articles can be simultaneously molded. The present invention relates to a molding die set as described above.
【0002】[0002]
【従来の技術】一般にプラスチックの射出成形品は、溶
融状態の熱可塑性プラスチックを分割可能な成形用金型
のキャビティ内に高圧で押し込み、固体状に冷えて固ま
った後、該金型を開いて取り出すことにより形成されて
いた。図3は、その成形用金型を示し、分割可能な金型
1,1’内のキャビティ7に、油圧シリンダー13で押
動されるラム12を内挿した加熱筒2の先端のノズル3
を、この金型1’に形成されたランナ、ゲートなどを介
して連通させている。なお、図において符号14は、粒
状の熱可塑性プラスチックを上記加熱筒2に供給する為
のホッパー、5は上記加熱筒2の周囲を循環する冷却
水、15はバンドヒータを示す。2. Description of the Related Art In general, a plastic injection molded product is formed by pressing a molten thermoplastic into a cavity of a mold capable of being divided at a high pressure, cooling to a solid state and solidifying, and then opening the mold. It was formed by taking out. FIG. 3 shows the molding die, in which a ram 12 pushed by a hydraulic cylinder 13 is inserted into a cavity 7 in a divisible mold 1, 1 ′.
Are communicated via a runner, a gate, and the like formed in the mold 1 ′. In the drawing, reference numeral 14 denotes a hopper for supplying granular thermoplastics to the heating cylinder 2, 5 denotes cooling water circulating around the heating cylinder 2, and 15 denotes a band heater.
【0003】しかし、上記金型で成形されたプラスチッ
ク成形品は、冷却固化の際の収縮で、表面にひけを生じ
たり、変形したりする為、表面の仕上げ状態が悪く、且
つ必要な精度も得られないという問題点があった。[0003] However, plastic molded articles molded by the above-mentioned molds have shrinkage or deformation on the surface due to shrinkage upon cooling and solidification, so that the finished state of the surface is poor and the required accuracy is low. There was a problem that it could not be obtained.
【0004】そこで、精度を要するプラスチック成形品
を得るために従来は、ひけの生じた成形品を、更に成形
してひけを補完する二重成形を行ったり、あるいは表面
側と内面側とを別々に成形した後、合体させて目的形状
の製品を形成するということが行われていた。[0004] Therefore, in order to obtain a plastic molded product requiring precision, conventionally, a molded product having sink marks is further molded to perform double molding to supplement sink marks, or separate surface and inner surfaces are used. After forming into a product, the product is combined to form a product having a desired shape.
【0005】なお、溶融プラスチックの冷却固化が遅い
厚肉部のひけを防止するものとしては、実開昭63−1
91013号、特開昭60−8026号、実開平2−1
04211号、特開昭63−281817号の各公報に
示されるものがある。[0005] In order to prevent sinking of a thick-walled portion where the cooling and solidification of the molten plastic is slow, Japanese Utility Model Application Laid-Open No. 63-1 / 1988 has disclosed the following.
No. 91013, JP-A-60-8026, and Japanese Utility Model Application 2-1
No. 04211 and JP-A-63-281817.
【0006】また複数の成形用キャビティを有する金型
においては、冷却の際に一方の金型を全体的に他方の金
型に押しつけるようにしたものが公知である。[0006] As for a mold having a plurality of molding cavities, it is known that one mold is entirely pressed against the other mold during cooling.
【0007】[0007]
【発明が解決しようとする課題】上述した通常の射出成
形では、冷却固化の際の収縮で、表面にひけを生じた
り、変形したりする為、表面の仕上げ状態が悪く、且つ
必要な精度も得られないという問題点を有していた。In the above-mentioned ordinary injection molding, shrinkage during cooling and solidification causes sink marks or deformation on the surface, so that the finished state of the surface is poor and the required accuracy is low. There was a problem that it could not be obtained.
【0008】又、これを防止する為に二重成形や分割成
形を行うと、製作の手間がかかると共に、金型も二種類
必要とし、コストアップの要因になるという問題点があ
った。Further, if double molding or split molding is performed in order to prevent this, it takes a lot of time and effort to manufacture, and two types of dies are required, resulting in an increase in cost.
【0009】また、実開昭63−191013号、特開
昭60−8026号、実開平2−104211号、特開
昭63−281817号の各公報に示された金型や方法
では、厚肉部に生じるひけは、防止されるものの、厚肉
部以外の個所に生じるひけや表面のあれは、防止され
ず、精度を要するものは、やはり上述した従来のものと
同様に二重成形や分割成形を行う必要があった。またこ
の金型では、ゲートとは別の個所にピンや押圧体を設け
ているので、成形品には、双方の痕跡が別々に残り、見
苦しいという問題点も有していた。The molds and methods disclosed in Japanese Utility Model Laid-Open No. 63-191013, Japanese Patent Laid-Open No. 60-8026, Japanese Utility Model Laid-Open No. 2-104211, and Japanese Patent Laid-Open No. Although sink marks in parts are prevented, sink marks and surface roughness in places other than the thick part are not prevented. Molding had to be performed. Further, in this mold, since the pins and the pressing body are provided at a place different from the gate, both traces are separately left on the molded product, which has a problem that it is unsightly.
【0010】更にまた複数の成形用キャビティを有する
金型において、冷却の際に一方の金型を全体的に他方の
金型に押しつけるようにしたものは、各成形用キャビテ
ィに押し込まれるプラスチック量が必ずしも均一ではな
く、又、その冷却速度も各キャビティ間で相違する為、
出来上がった製品にばらつきが生じると共に、十分な寸
法精度も得られないという問題点を有していた。Further, in a mold having a plurality of molding cavities, one mold is entirely pressed against the other mold during cooling, and the amount of plastic pushed into each molding cavity is limited. It is not always uniform, and the cooling rate differs between each cavity.
There is a problem that the finished product varies, and that sufficient dimensional accuracy cannot be obtained.
【0011】本発明は、これら従来の問題点の解決を課
題とする。An object of the present invention is to solve these conventional problems.
【0012】[0012]
【課題を解決する為の手段】本発明のうち、請求項1記
載の発明は、熱可塑性プラスチックの射出成形品におい
て、溶融プラスチックの供給個所に形成されるゲート痕
の周囲に、押し込みにより冷却時の体積変化を吸収した
押込痕が形成されたことを特徴とする。According to a first aspect of the present invention, there is provided an injection molded article made of a thermoplastic plastic, which is formed by pushing around a gate mark formed at a supply point of a molten plastic by cooling. Characterized by the fact that a pressing mark that absorbs the change in volume is formed.
【0013】また、請求項2記載の発明は、複数の成形
用キャビティを有するプラスチックの射出成形用の金型
において、溶融したプラスチックが押し出される各キャ
ビティに、それぞれその先端を臨ませて押圧手段により
押し出される押圧体を設け、各押圧体には、一端が射出
機のノズルと連通し、他端がゲートを介してキャビティ
内と連通したランナを有するランナブッシュを内装し、
溶融プラスチックの供給個所の周囲を押圧するようにし
たことを特徴とする。According to a second aspect of the present invention, in a plastic injection mold having a plurality of molding cavities, the tip of each of the cavities through which the molten plastic is extruded is pressed by pressing means. A pressing body to be extruded is provided, and each pressing body includes a runner bush having a runner having one end communicating with the nozzle of the injection machine and the other end communicating with the inside of the cavity through a gate,
The present invention is characterized in that the periphery of the supply point of the molten plastic is pressed.
【0014】[0014]
【作用】個々の成形用キャビティ内に押し出される各押
圧体は、冷却の際、それぞれの成形品の溶融プラスチッ
クの供給個所の周囲を押しつけることにより、各成形品
の収縮の際の体積変化を個別にこの押圧部分で吸収し、
他の箇所でのひけや変形を防止するように作用する。[Function] Each pressing body pushed into an individual molding cavity presses the periphery of the molten plastic supply point of each molded product during cooling, thereby individually changing the volume change during shrinkage of each molded product. Absorbed by this pressed part,
It acts to prevent sinking and deformation at other locations.
【0015】[0015]
【実施例】図1は、本発明の成形用金型を、容器キャッ
プの成形用金型を例に示した簡略断面図である。図示し
たように本発明のプラスチックの成形品用金型は、従来
と同様に分割可能な射出成形用金型1,1’のキャビテ
ィ7内に射出機のノズル(図示せず)をランナ17など
を介して連通させたものである。FIG. 1 is a simplified sectional view showing a molding die according to the present invention, taking a container cap molding die as an example. As shown in the drawing, the plastic molding die according to the present invention has a nozzle (not shown) of an injection machine in a cavity 7 of an injection molding die 1, 1 'which can be divided in the same manner as in the prior art. Are communicated with each other.
【0016】ここにおいて、本発明ではキャビティ7内
に出没可能に押圧体4を設け、この押圧体4に溶融プラ
スチックの通路となるランナ17を設けたランナブッシ
ュ16を内装している。このランナブッシュ16は、一
端が図示しない射出機のノズルに連通すると共に、他端
が極めて小径の孔であるピンゲート(図示せず)を介し
てキャビティ7内に連通している。なお、このように成
形品の裏側となる固定側(射出機のノズルを設けた側)
の金型6にピンゲートを配したものは、特に裏ピンゲー
トと称される。Here, in the present invention, the pressing body 4 is provided so as to be able to protrude and retract in the cavity 7, and a runner bush 16 provided with a runner 17 serving as a passage for the molten plastic is provided inside the pressing body 4. One end of the runner bush 16 communicates with a nozzle of an injection machine (not shown), and the other end communicates with the cavity 7 via a pin gate (not shown) which is an extremely small hole. The fixed side (the side on which the nozzle of the injection machine is provided) which is the back side of the molded product
A mold in which a pin gate is arranged on a mold 6 is particularly called a back pin gate.
【0017】上記押圧体4は、その後端のピストン部
4’を上記キャビティ7内に嵌入した固定側金型6の後
部に一体的に形成したシリンダー6’に嵌合させてい
る。The pressing body 4 has a piston 4 'at the rear end fitted to a cylinder 6' integrally formed at the rear of the fixed mold 6 fitted in the cavity 7.
【0018】なお、5は上記ランナブッシュ16を冷却
する冷却水、8,9は油圧駆動用の油を供給する送油
口、10,11は上記シリンダー6’内の油圧室を示
す。Reference numeral 5 denotes cooling water for cooling the runner bush 16, reference numerals 8 and 9 denote oil supply ports for supplying oil for hydraulic drive, and reference numerals 10 and 11 denote hydraulic chambers in the cylinder 6 '.
【0019】上記は1つの成形用キャビティを例示した
が、同様の押圧体は、金型に形成された各成形用キャビ
ティにそれぞれ設けられていることとする。Although one molding cavity has been exemplified above, it is assumed that similar pressing members are provided in each molding cavity formed in the mold.
【0020】このようにして成る本発明の成形用金型
は、通常の射出成形と同様に射出機のノズル(図示せ
ず)から押し出された溶融状態の熱可塑性プラスチック
を、ランナ17などを介してゲート(図示せず)からキ
ャビティ7内に高圧で押し込むことにより、所望形状の
成形品を得るものであるが、ここにおいて本発明では、
所定量のプラスチックを押し込んだ後、直ちに図示しな
い油圧機構で送油口9からシリンダー6’後部の油圧室
11内に油を送り込むこととしている。このことによ
り、該シリンダー6’の内部に密嵌したピストン部4’
は図中右方向に押動される力を受け、先端の押圧体4は
常に所定圧力でキャビティ7内のプラスチックに押しつ
けられることとなる。よって、キャビティ7内のプラス
チックは、ゲートから離れたキャビティの隅々まで行き
渡ると共に、冷却され、その体積が減少するにつれて押
圧体4が内部に食い込み、その体積変化が吸収されるも
のである。そして、冷却が完了し、プラスチックが固ま
ると、今度は送油口8から油圧室10内に油を送り込
み、該押圧体4を反対方向に駆動して原状に復帰させ、
金型1,1’を分割して成形品を取り出すものである。The thus-formed molding die of the present invention is similar to ordinary injection molding, in that a molten thermoplastic extruded from a nozzle (not shown) of an injection machine is passed through a runner 17 or the like. The molded product having a desired shape is obtained by pushing the molded product into the cavity 7 at a high pressure from a gate (not shown).
Immediately after a predetermined amount of plastic is pushed in, oil is fed from the oil feed port 9 into the hydraulic chamber 11 at the rear of the cylinder 6 'by a hydraulic mechanism (not shown). As a result, the piston portion 4 'closely fitted inside the cylinder 6'
Receives a force to be pushed rightward in the drawing, and the pressing body 4 at the tip is constantly pressed against the plastic in the cavity 7 at a predetermined pressure. Therefore, the plastic in the cavity 7 spreads to every corner of the cavity away from the gate, is cooled, and as the volume decreases, the pressing body 4 digs into the inside, and the volume change is absorbed. When the cooling is completed and the plastic is solidified, oil is fed into the hydraulic chamber 10 from the oil feed port 8 and the pressing body 4 is driven in the opposite direction to return to the original state.
A mold is taken out by dividing the molds 1 and 1 '.
【0021】図2は、このようにして形成された成形品
aの断面図である。図示したように本発明のプラスチッ
クの射出成形品aには、その裏面など製品の品質を損な
わない箇所に冷却時の体積変化を吸収した押込痕a’が
残ることにより、他の箇所でのひけや変形を防止して高
い精度に成形されるものである。又、溶融状態のプラス
チックが押圧されることにより、キャビティ7の隅々に
までプラスチックが行き渡り、厚肉や薄肉のリブなどの
加工が一工程で可能になると共に、その細部の加工性も
向上する。さらに金型のコア側のキャビティ7内に押し
出し可能に押圧体4を設けているので、この箇所から成
形時のガス抜きもなされることとなり、一層高い精度に
成形されると共に、成形品にガス溜まりに起因するやけ
も生じない。FIG. 2 is a sectional view of the molded article a formed in this manner. As shown in the figure, the plastic injection molded article a of the present invention has indentation marks a ′ that absorb the volume change during cooling left at places where the quality of the product is not impaired, such as the back surface, so that sinks at other places can be made. It is molded with high precision while preventing deformation. Further, when the plastic in the molten state is pressed, the plastic spreads to every corner of the cavity 7, and processing of thick or thin ribs and the like can be performed in one step, and the workability of the details can be improved. . Further, since the pressing body 4 is provided so as to be able to be pushed out into the cavity 7 on the core side of the mold, gas is released from the molding at the time of molding. There is no burn due to accumulation.
【0022】尚、上記押込痕a’の中心には、その成形
上、必然的に生じるゲート痕(図示せず)も存在する。At the center of the indentation mark a ', there is also a gate mark (not shown) which is inevitably formed during molding.
【0023】このように本発明のプラスチックの射出成
形品aでは、ゲート痕と押込痕とが内側の目立たない場
所に重なり合って形成され、外部の視認可能な場所に
は、一切痕跡が残らず、その外観が極めて良好に成形さ
れる。As described above, in the plastic injection-molded article a of the present invention, the gate mark and the push mark are formed so as to overlap with each other at an inconspicuous place on the inside, and no trace remains at a place visible outside. Its appearance is very well formed.
【0024】尚、本実施例では、冷却時に押圧体が成形
品内に押し込まれる例を示したが、予め熱収縮により押
し込まれる量を想定して押圧体を後退させておいても良
く、このようにすることにより、押込痕を目立たなくす
ることもできる。In this embodiment, the example in which the pressing body is pushed into the molded article at the time of cooling is shown. However, the pressing body may be retracted in advance by assuming the amount to be pushed by thermal contraction. By doing so, it is also possible to make indentations inconspicuous.
【0025】又、実施例では、押圧体の駆動手段として
油圧を用いた例を示したが、押圧体の駆動手段は油圧に
限らず、空気圧、その他、電気的、機械的に駆動するも
のであっても良い。Further, in the embodiment, an example in which hydraulic pressure is used as the driving means of the pressing body has been described. However, the driving means of the pressing body is not limited to hydraulic pressure, but may be pneumatically or otherwise electrically or mechanically driven. There may be.
【0026】[0026]
【発明の効果】以上の通り、本発明のプラスチック成形
品は、一工程の射出成形により形成されるにもかかわら
ず、ひけや寸法誤差が殆ど生じないので、従来のような
二重成形や分割成形を必要とせず、高品質な製品をコス
ト低廉に提供できる。As described above, the plastic molded article of the present invention hardly causes sink marks and dimensional errors despite being formed by one-step injection molding. High quality products can be provided at low cost without the need for molding.
【0027】又、その成形用金型は、一工程でひけや寸
法誤差の殆ど生じない等品質の成形品を同時に複数成形
できるので、従来の二重成形や分割成形のように複数の
金型を必要とせず、製品の品質が向上すると共に、生産
能率が向上し、設備投資費も削減されるという多くの優
れた効果を奏する。In addition, since the molding die can simultaneously mold a plurality of molded products of the same quality with almost no sink mark or dimensional error in one process, a plurality of molds are required as in the conventional double molding or split molding. In addition to the above advantages, the present invention has many excellent effects of improving product quality, improving production efficiency, and reducing capital investment costs.
【図1】本発明による成形用金型の実施例を示す簡略断
面図である。FIG. 1 is a simplified sectional view showing an embodiment of a molding die according to the present invention.
【図2】本発明によるプラスチック成形品の実施例を示
す断面図である。FIG. 2 is a sectional view showing an embodiment of a plastic molded product according to the present invention.
【図3】射出成形用金型の従来例を示す断面図である。FIG. 3 is a cross-sectional view showing a conventional example of an injection mold.
1,1’ 金型 4 押圧体 4’ ピストン部 5 冷却水 6 固定側金型 7 キャビティ 8,9 送油口 10,11 油圧室 16 ランナブッシュ 17 ランナ a プラスチック成形品 a’ 押込痕 1,1 'Mold 4 Pressing Body 4' Piston 5 Cooling Water 6 Fixed Mold 7 Cavity 8,9 Oil Feeding Port 10,11 Hydraulic Chamber 16 Runner Bush 17 Runner a Plastic Molded Product a 'Press Mark
Claims (2)
いて、 溶融プラスチックの供給個所に形成されるゲート痕の周
囲に、冷却時の体積変化を吸収した押込痕が形成されて
いることを特徴とするプラスチックの射出成形品。1. A plastic injection molded article, characterized in that, around a gate mark formed at a supply point of a molten plastic, a press mark absorbing a volume change during cooling is formed. Injection molded products.
チックの射出成形用の金型において、 溶融したプラスチックが押し出される各キャビティに、
それぞれその先端を臨ませて押圧手段により押し出され
る押圧体が設けられ、各押圧体には、一端が射出機のノ
ズルと連通し、他端がゲートを介してキャビティ内と連
通したランナを有するランナブッシュが内装され、溶融
プラスチックの供給個所の周囲が、押圧されるようにな
されたことを特徴とするプラスチックの成形用金型。2. A mold for injection molding a plastic having a plurality of molding cavities, wherein:
Each of the pressing bodies has a runner having a runner whose one end communicates with the nozzle of the injection machine and whose other end communicates with the inside of the cavity through a gate. A mold for molding plastic, wherein a bush is provided inside and a periphery of a supply point of molten plastic is pressed.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5205841A JP2587900B2 (en) | 1993-07-27 | 1993-07-27 | Plastic injection molded products and their molds |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5205841A JP2587900B2 (en) | 1993-07-27 | 1993-07-27 | Plastic injection molded products and their molds |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0740394A JPH0740394A (en) | 1995-02-10 |
JP2587900B2 true JP2587900B2 (en) | 1997-03-05 |
Family
ID=16513605
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP5205841A Expired - Fee Related JP2587900B2 (en) | 1993-07-27 | 1993-07-27 | Plastic injection molded products and their molds |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2587900B2 (en) |
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Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS608026A (en) * | 1983-06-28 | 1985-01-16 | Ichikoh Ind Ltd | Injection molding method of synthetic resin |
JPS63281817A (en) * | 1987-05-14 | 1988-11-18 | Matsushita Electric Ind Co Ltd | Injection mold assembly |
JPS63191013U (en) * | 1987-05-22 | 1988-12-08 | ||
JPH02104211U (en) * | 1989-02-07 | 1990-08-20 |
-
1993
- 1993-07-27 JP JP5205841A patent/JP2587900B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
JPH0740394A (en) | 1995-02-10 |
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