JP3441686B2 - Gas injection part structure in gas injection molding die - Google Patents
Gas injection part structure in gas injection molding dieInfo
- Publication number
- JP3441686B2 JP3441686B2 JP31546799A JP31546799A JP3441686B2 JP 3441686 B2 JP3441686 B2 JP 3441686B2 JP 31546799 A JP31546799 A JP 31546799A JP 31546799 A JP31546799 A JP 31546799A JP 3441686 B2 JP3441686 B2 JP 3441686B2
- Authority
- JP
- Japan
- Prior art keywords
- gas injection
- gas
- molding
- nozzle
- injection molding
- 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
- 238000002347 injection Methods 0.000 title claims description 34
- 239000007924 injection Substances 0.000 title claims description 34
- 238000001746 injection moulding Methods 0.000 title description 15
- 238000000465 moulding Methods 0.000 claims description 19
- 229920005989 resin Polymers 0.000 claims description 11
- 239000011347 resin Substances 0.000 claims description 11
- 230000002093 peripheral effect Effects 0.000 claims description 9
- 239000007789 gas Substances 0.000 description 52
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 10
- 229910001873 dinitrogen Inorganic materials 0.000 description 10
- 238000009423 ventilation Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 3
- 239000000758 substrate Substances 0.000 description 2
- 229920005992 thermoplastic resin Polymers 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/1703—Introducing an auxiliary fluid into the mould
- B29C45/1734—Nozzles therefor
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Description
【発明の詳細な説明】
【０００１】
【発明の属する技術分野】本発明は、成形窩内に熱可塑
性樹脂を射出するのに引き続いて高圧の窒素ガスを注入
するガスインジェクション成形における金型のガス注入
部構造に関するものである。
【０００２】
【従来の技術】ガスインジェクション成形（ガス・アシ
スト射出成形とも称される）は、周知のように、金型の
成形窩（キャビティ）内に熱可塑性樹脂を射出するのに
引き続いて高圧の窒素ガスを注入することにより、該成
形窩内を保圧し、成形品を中空状にして、成形品の反
り，ヒケ等の発生を防止するとともに、成形品を軽量化
する射出成形方法である。
【０００３】従来からこのガスインジェクション成形で
は、射出成形機の樹脂射出ノズルからガスを注入する方
式と、金型に別途に設けたガス注入ノズルからガスを注
入する方式とがある。図４は後者の方式を示した金型の
縦断面図で、図中、１は固定型２と可動型３により形成
される成形窩（キャビティ）、４は樹脂射出口、５は成
形窩１に延設された円錐台形のボス形成部、６は先端が
該ボス形成部中に臨むように固設されたガス注入ノズル
である。該ガス注入ノズルは、図５に従来のガス注入部
を拡大して示したように、円筒状のスリーブ７中に通気
間隙８が存せられるように円柱状のコアピン９が配置さ
れ、高圧の窒素ガスＧを該通気間隙８を通して成形窩１
内に注入するものである。なお、ＲはガスＧの注入に先
立って成形窩１内に射出された樹脂を示す。
【０００４】ところで、このような従来のガス注入部の
構造では、成形窩１内に注入された窒素ガスＧが、図６
に示したように、その高圧によってスリーブ７の外周面
に沿って樹脂との隙間ｇを作って外に漏れることがあっ
た。そのために成形品内のガス圧力制御が困難となり、
注入ガスが成形窩の末端部まで回らず成形品に例えばヒ
ケｎを生じさせ品質が維持できないなど所期のガスイン
ジェクション成形ができなくなるという問題があった。
【０００５】これを防ぐために従来は上記ボス形成部５
の高さｈを６〜８ｍｍ程度に高く突出させていたが、こ
の高さは成形品によっては美観を損ねたり形状規制され
るので、成形後にこのボスをカットしなければならなく
なり二次加工のコストが高くなるおそれがあるととも
に、たとえ高く突出させたとしても十分な洩れ防止がで
きない状況であった。またこのガス漏れを補填するべく
ガスを供給するとガス消費量が多くなるとともに、ガス
注入に時間がかかるので稼働率が落ち生産性を悪くする
問題があった。
【０００６】
【発明が解決しようとする課題】そこで本発明は上記の
ようなガス注入部からのガス漏れを防止し所期のガスイ
ンジェクション成形を常に安定して実行し得るようにす
るものである。
【０００７】
【課題を解決するための手段】そのために本発明のガス
インジェクション成形用金型におけるガス注入部構造
は、金型の成形窩中に突出するガス注入用ノズルの外周
面に拡径段部を形成し、該拡径段部の段差面および外周
面が射出された樹脂に接するように該ノズルを金型に設
定してなることを特徴とする。
【０００８】
【発明の実施の形態】次に図面に従い本発明の実施の形
態を説明する。図１は本発明に係るガスインジェクショ
ン成形用金型におけるガス注入部の縦断面図で、１は固
定型２と可動型３により形成される成形窩（キャビテ
ィ）、５は該成形窩に延設された円錐台形のボス形成
部、６は先端が該成形窩中に臨むように固設されたガス
注入ノズルである。該ガス注入ノズル６は、可動型３の
外面にボルト１０によって固定された取付基板１１に円
筒状のスリーブ７が設けられ、該スリーブ中に０．０３
〜０．１ｍｍ程度の通気間隙８が存せられるように円柱
状のコアピン９を挿入し該コアピン９を螺旋蓋１２によ
って固定するとともに、該通気間隙８と連通する給気路
１３を取付基板１１中に形成し、給気口１４より窒素ガ
スＧを数百気圧の高圧力で成形窩１中に注入し得るよう
にしている。なお、Ｒは窒素ガスＧの注入に先立って成
形窩１内に射出された樹脂を示す。
【０００９】そして本発明にかかるガス注入ノズル６で
は、スリーブ７の外周面に基部に向かい途中から外径を
急拡大することにより拡径段部１５を形成し、該拡径段
部の段差面１９および外周面が射出された樹脂に接する
ように設定している。このため、同図に示したように該
ノズルの外周面が軸方向に向かって曲折し、注入された
窒素ガスＧがたとえノズル６外周面に沿って樹脂との間
に隙間ｇを作って外方に流れ出ようとしても拡径段部１
５によって流出が阻まれる。なおこの段部１５の高さは
ガス流出阻止のため０．５ｍｍ以上とするのが望まし
い。【００１０】
また、図２に示した実施形態は、裏面にリ
ブ２０を有する板状品２１を成形するためその成形窩１
に表側から図１に示した拡径段部１５を有したガス注入
ノズル６を突出させてなるもので、この場合、成形窩１
のリブ形成用基部２２にガス注入ノズル６を突出させた
ことによって十分な厚みが確保されるので、上記実施形
態のようにあえてボス形成部を設けなくてもよい。
【００１１】一方、図３は、拡径段部１５の段差面１９
を基部方向に向かいテーパ状に縮径した形態とし、該段
差面１９が成形窩１の成形面（ボス形成部５の先端面）
をなすように該ノズル６を金型に設定してなるものであ
る。こうすることによっても窒素ガスの直進をより効果
的に防ぎ漏洩を阻止できるようになる。【００１２】
なお、ガス注入ノズル６の外周には上記実
施形態のように拡径段部１５を設けたうえでさらに凹凸
および粗面を設けることでその相乗効果としてガスの漏
出防止が確実になる。【００１３】
【発明の効果】このように本発明に係るガスインジェク
ション成形用金型におけるガス注入部構造によれば、成
形窩に注入された窒素ガスがノズルの外周面に沿って漏
出するのを防止できるので、注入ガスの圧力を容易に制
御できるようになり、注入ガスの回りをよくして成形品
の品質を向上させるとともに、ガス消費量が抑えられ成
形時間の短縮ともなり生産性が向上する。また従来のよ
うに成形品にガス注入のための高いボスを形成しなくて
もよくなるなど種々の有益な効果がある。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold gas for gas injection molding in which a high-pressure nitrogen gas is injected following injection of a thermoplastic resin into a molding cavity. It relates to the structure of the injection part. [0002] Gas injection molding (also referred to as gas-assisted injection molding), as is well known, involves the injection of a thermoplastic resin into a mold cavity followed by high pressure. Is an injection molding method in which the pressure in the molding cavity is maintained by injecting nitrogen gas to make the molded product hollow, preventing the molded product from warping or sinking, and reducing the weight of the molded product. . Conventionally, in the gas injection molding, there are a method of injecting a gas from a resin injection nozzle of an injection molding machine and a method of injecting a gas from a gas injection nozzle separately provided in a mold. FIG. 4 is a longitudinal sectional view of a mold showing the latter method. In the figure, reference numeral 1 denotes a molding cavity (cavity) formed by a fixed mold 2 and a movable mold 3; 4, a resin injection port; A boss forming portion having a truncated conical shape, and a gas injection nozzle 6 fixed so that a tip thereof faces the boss forming portion. As shown in an enlarged view of a conventional gas injection portion in FIG. 5 , the gas injection nozzle has a cylindrical core pin 9 disposed so that a ventilation gap 8 is provided in a cylindrical sleeve 7, and a high-pressure gas injection nozzle. Nitrogen gas G is passed through the ventilation gap 8 to form the molding cavity 1.
It is to be injected into. R indicates the resin injected into the molding cavity 1 prior to the injection of the gas G. [0004] In the structure of such a conventional gas injection unit, a nitrogen gas G is injected into the molding fossa 1, FIG. 6
As shown in FIG. 7, the high pressure may cause a gap g with the resin along the outer peripheral surface of the sleeve 7 to leak out. This makes it difficult to control the gas pressure in the molded product,
There is a problem that the desired gas injection molding cannot be performed, for example, because the injected gas does not reach the end of the molding cavity, for example, sink marks are generated in the molded product and the quality cannot be maintained. In order to prevent this, conventionally, the boss forming portion 5 is used.
The height h is projected to be as high as about 6 to 8 mm. However, depending on the molded product, the appearance is impaired or the shape is restricted. The cost may be high, and even if the protruding portion is protruded high, sufficient leakage cannot be prevented. In addition, when gas is supplied to compensate for the gas leakage, the gas consumption increases, and the gas injection takes a long time, so that there is a problem that the operation rate is reduced and productivity is deteriorated. SUMMARY OF THE INVENTION Accordingly, the present invention is to prevent the above-mentioned gas leakage from the gas injection portion and to stably carry out the intended gas injection molding. . [0007] For this purpose, the gas injection part structure of the gas injection molding die according to the present invention comprises a step of increasing the diameter of the gas injection nozzle protruding into the molding cavity of the die. The nozzle is set in a mold so that a step surface and an outer peripheral surface of the enlarged diameter step portion are in contact with the injected resin. Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a gas injection portion in a gas injection molding die according to the present invention, wherein 1 is a molding cavity (cavity) formed by a fixed mold 2 and a movable mold 3 and 5 is extended into the molding cavity. The frusto-conical boss forming portion 6 is a gas injection nozzle fixed so that the front end faces into the molding cavity. The gas injection nozzle 6 is provided with a cylindrical sleeve 7 on a mounting substrate 11 fixed to the outer surface of the movable mold 3 by bolts 10.
A cylindrical core pin 9 is inserted so as to have a ventilation gap 8 of about 0.1 mm, the core pin 9 is fixed by a spiral lid 12, and an air supply passage 13 communicating with the ventilation gap 8 is attached to a mounting substrate 11. The nitrogen gas G can be injected into the molding cavity 1 from the air supply port 14 at a high pressure of several hundred atmospheres. R indicates the resin injected into the molding cavity 1 prior to the injection of the nitrogen gas G. [0009] Then the gas injection nozzle 6 of the present invention, to form the enlarged diameter stepped portion 15 by rapid expansion of the outer diameter from the middle towards the base on the outer peripheral surface of the sleeve 7, the enlarged diameter section
The step surface 19 and the outer peripheral surface of the portion are in contact with the injected resin.
Is set as follows. For this reason, as shown in the figure, the outer peripheral surface of the nozzle is bent in the axial direction, and the injected nitrogen gas G creates a gap g between the resin and the resin along the outer peripheral surface of the nozzle 6, for example. Large diameter step 1
5 prevents outflow. The height of the step 15 is desirably 0.5 mm or more to prevent gas outflow. The embodiment shown in FIG. 2 uses a molding cavity 1 for molding a plate-like article 21 having a rib 20 on the back surface.
The gas injection nozzle 6 having the enlarged diameter step 15 shown in FIG. 1 is projected from the front side.
Since the gas injection nozzle 6 protrudes from the rib forming base 22 to secure a sufficient thickness, it is not necessary to provide a boss forming portion as in the above embodiment. Meanwhile, FIG. 3, the stepped surface 19 of the expansion-diameter step portion 15
Is tapered toward the base direction, and the step surface 19 is formed on the forming surface of the forming cavity 1 (the end surface of the boss forming portion 5).
The nozzle 6 is set in a mold so that This also makes it possible to more effectively prevent the nitrogen gas from going straight and prevent leakage. The gas injection nozzle 6 is provided with a stepped- diameter step 15 on the outer periphery thereof as in the above-described embodiment, and is further provided with irregularities and a rough surface. As a synergistic effect, prevention of gas leakage is ensured. . [0013] Effect of the Invention According to the gas injection unit structure in gas injection molding die according to the present invention, the nitrogen gas injected into the molding fossa from leaking along the outer peripheral surface of the nozzle Can improve the quality of the molded product by improving the flow of the injected gas, and reduce the gas consumption, shorten the molding time and improve productivity. I do. In addition, there are various beneficial effects, such as eliminating the need for forming a high boss for gas injection in a molded product as in the related art.
【図面の簡単な説明】
【図１】本発明の実施形態を示すガスインジェクション
成形用金型におけるガス注入部の縦断面図。
【図２】本発明の実施形態を示したガス注入部の縦断面
図。
【図３】本発明の実施形態を示したガス注入部の縦断面
図。
【図４】従来のガスインジェクション成形用金型の縦断
面図。
【図５】従来のガスインジェクション成形用金型のガス
注入部の縦断面図。
【図６】図５のガス注入部におけるガス漏れの模様を示
した縦断面図。
【符号の説明】
１ 成形窩
２ 固定型
３ 可動型
５ ボス形成部
６ ガス注入ノズル
７ スリーブ
８ 通気間隙
９ コアピン
１４ 給気口
１５ 拡径段部
１９ 段差面
２２ リブ形成用基部
Ｇ 窒素ガス
Ｒ 樹脂BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a gas injection part in a gas injection molding die according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of a gas injection unit according to the embodiment of the present invention. FIG. 3 is a vertical cross-sectional view of a gas injection section showing an embodiment of the present invention. FIG. 4 is a longitudinal section of a conventional gas injection molding die.
Area view. FIG. 5 shows gas in a conventional gas injection molding mold.
The longitudinal section of an injection part. FIG. 6 shows a gas leak pattern in the gas injection part of FIG .
Longitudinal section view. [Description of Signs] 1 Molding cavity 2 Fixed mold 3 Movable mold 5 Boss forming section 6 Gas injection nozzle 7 Sleeve 8 Ventilation gap 9 Core pin 14 Air supply port 15 Large- diameter step section 19 Step surface 22 Rib forming base G Nitrogen gas R resin
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平７−60780（ＪＰ，Ａ) 特開 平７−290508（ＪＰ，Ａ) 特開 平10−100203（ＪＰ，Ａ) 特開 平11−226987（ＪＰ，Ａ) 特開 平９−1593（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B29C 45/00 - 45/84 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-7-60780 (JP, A) JP-A-7-290508 (JP, A) JP-A-10-100203 (JP, A) JP-A-11- 226987 (JP, A) JP-A-9-1593 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) B29C 45/00-45/84
Claims (1)
ズルの外周面に拡径段部を形成し、該拡径段部の段差面
および外周面が射出された樹脂に接するように該ノズル
を金型に設定してなることを特徴としたガスインジェク
ション成形用金型におけるガス注入部構造。(57) [Claim 1] An enlarged diameter step portion is formed on an outer peripheral surface of a gas injection nozzle protruding into a molding cavity of a mold, and a step surface and an outer peripheral surface of the enlarged diameter step portion are formed. Wherein the nozzle is set in a mold such that the nozzle is in contact with the injected resin.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31546799A JP3441686B2 (en) | 1999-11-05 | 1999-11-05 | Gas injection part structure in gas injection molding die |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31546799A JP3441686B2 (en) | 1999-11-05 | 1999-11-05 | Gas injection part structure in gas injection molding die |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2003118937A Division JP2003311788A (en) | 2003-04-23 | 2003-04-23 | Structure of gas injection part in mold for gas injection molding |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001129855A JP2001129855A (en) | 2001-05-15 |
| JP3441686B2 true JP3441686B2 (en) | 2003-09-02 |
Family
ID=18065718
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP31546799A Expired - Fee Related JP3441686B2 (en) | 1999-11-05 | 1999-11-05 | Gas injection part structure in gas injection molding die |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3441686B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4609290B2 (en) * | 2005-11-28 | 2011-01-12 | 豊田合成株式会社 | Resin molded product and manufacturing method thereof |
-
1999
- 1999-11-05 JP JP31546799A patent/JP3441686B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2001129855A (en) | 2001-05-15 |
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