JPH1071641A - Mold apparatus for biaxial stretching blow molding - Google Patents

Mold apparatus for biaxial stretching blow molding

Info

Publication number
JPH1071641A
JPH1071641A JP8248942A JP24894296A JPH1071641A JP H1071641 A JPH1071641 A JP H1071641A JP 8248942 A JP8248942 A JP 8248942A JP 24894296 A JP24894296 A JP 24894296A JP H1071641 A JPH1071641 A JP H1071641A
Authority
JP
Japan
Prior art keywords
support pin
preform
blow
mold
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.)
Pending
Application number
JP8248942A
Other languages
Japanese (ja)
Inventor
Hiromichi Saito
浩道 斉藤
Hiroaki Sugiura
弘章 杉浦
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.)
Yoshino Kogyosho Co Ltd
Original Assignee
Yoshino Kogyosho Co 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 Yoshino Kogyosho Co Ltd filed Critical Yoshino Kogyosho Co Ltd
Priority to JP8248942A priority Critical patent/JPH1071641A/en
Publication of JPH1071641A publication Critical patent/JPH1071641A/en
Pending legal-status Critical Current

Links

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
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/08—Biaxial stretching during blow-moulding
    • B29C49/10—Biaxial stretching during blow-moulding using mechanical means for prestretching
    • B29C49/12—Stretching rods
    • 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
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/42—Component parts, details or accessories; Auxiliary operations
    • B29C49/48—Moulds
    • B29C2049/4879—Moulds characterised by mould configurations
    • B29C2049/4892—Mould halves consisting of an independent main and bottom part
    • 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
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/08—Biaxial stretching during blow-moulding
    • B29C49/10—Biaxial stretching during blow-moulding using mechanical means for prestretching
    • B29C49/12—Stretching rods
    • B29C49/1208—Stretching rods using additional means to clamp the preform bottom while stretching the preform

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)

Abstract

PROBLEM TO BE SOLVED: To hold a preform so that the stretching center of the bottom part thereof is not displaced by providing an elastic material exerting elastic action on a support pin in the advance direction thereof in the vicinity of the retreat limit of a blow process in a cylinder chamber and forming the leading end surface of the support pin into a circumference-of-circle edge having a recessed cross-sectional shape. SOLUTION: A support pin 6 is inserted into the cylinder chamber 3a formed to the bottom mold 3 of a blow mold in a freely advancing and retreating manner to be arranged in order to prevent the wall thickness irregularity of a product subjected to blow molding and the leading end surface 6a of a support pin is formed into a circumference-of-circle edge having a recessed cross-sectional shape so that resistance of a degree preventing the slide of the bottom part 4a of a perform 4 is provided but the deformation of the preform is not obstructed at a time of the stretching blow molding of the preform 4. Further, the support pin is brought to an energizing state in an advance direction at a retreat position by an elastic material 3c and the stretching center part of the bottom part 4a of the preform is held by the leading end surface 6a of the support pin and the leading end surface 5a of the stretching rod 5 provided to a blow core mold 2 to prevent the displacement of the stretching center of the preform.

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】本願発明は、熱可塑性合成樹
を中空容器にブロー成形する装置に係わり、更に詳しく
は、ポリエチレンテレフタレート樹脂を射出成形したプ
リフォームを２軸延伸ブロー成形して、耐熱性、耐圧
性、耐衝撃性に優れた中空容器を成形するための成形金
型装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for blow molding a thermoplastic synthetic resin into a hollow container. More specifically, the present invention relates to a biaxially stretch blow-molded preform obtained by injection molding a polyethylene terephthalate resin. TECHNICAL FIELD The present invention relates to a molding die apparatus for molding a hollow container having excellent pressure resistance and impact resistance.

【０００２】[0002]

【従来の技術】ポリエチレンやポリプロピレン等の熱可
塑性合成樹をブロー成形した中空容器は、透明性があ
り、軽量で耐衝撃性、耐薬品性に優れているので、種々
の液体収容容器として用いられているが、酸素や炭酸ガ
ス等の気体を透過し易いという欠点がある。そこで、近
年は、透明で機械的強度にも優れており、ガスバリヤー
性にも優れているポリエチレンテレフタレート樹脂を２
軸延伸ブロー成形した中空容器が、多用されるようにな
っている。2. Description of the Related Art Hollow containers made of blown thermoplastic synthetic resin such as polyethylene or polypropylene are used as various liquid containers because they are transparent, lightweight, and excellent in impact resistance and chemical resistance. However, there is a drawback that gas such as oxygen and carbon dioxide is easily permeated. Therefore, in recent years, a polyethylene terephthalate resin which is transparent, has excellent mechanical strength, and has excellent gas barrier properties has been developed.
Axial stretch blow-molded hollow containers are used frequently.

【０００３】ポリエチレンテレフタレート樹脂（以下、
ＰＥＴ樹脂と称する）、その他の熱可塑性樹脂を２軸延
伸ブロー成形して中空容器とするには、加熱溶融したＰ
ＥＴ樹脂等を射出成形により最終製品に適したプリフォ
ームに予備成形した後、該プリフォームをブロー成形金
型内で２軸方向に延伸ブロー成形を行って中空容器に成
形する方法が一般的である。そして、このようにしてＰ
ＥＴ樹脂を２軸方向に延伸ブロー成形する方法として
は、射出成形により予備成形したプリフォームを、所定
の延伸成形が可能な温度に加熱した後、口頸部をブロー
金型に挟持して単純にブロー成形するもの（特開昭５１
−５３５６６号）や、前記プリフォームを、ブロー金型
に口頸部を挟持して、ブローピンと同軸に設けた延伸ロ
ッドにより縦軸方向に延伸させながらブロー成形するも
の（特開昭５７−１２６１７号）等が知られているが、
このような方法によりブロー成形を行なうと、プリフォ
ーム内に吹き込まれる空気圧による振動現象によってプ
リフォームが横振れを起こして中空容器に偏肉を生じ易
いという欠点がある。[0003] Polyethylene terephthalate resin (hereinafter, referred to as
PET resin) and other thermoplastic resins are biaxially stretch blow-molded to form a hollow container.
After preforming an ET resin or the like into a preform suitable for the final product by injection molding, the preform is subjected to biaxial stretching blow molding in a blow molding mold to form a hollow container. is there. And in this way P
As a method of stretch-blow-molding the ET resin in the biaxial direction, a preform preformed by injection molding is heated to a temperature at which a predetermined stretch-molding can be performed, and then the mouth and neck are sandwiched between blow molds. To be blow-molded on
(Japanese Patent Application Laid-Open No. 57-12617), and a method in which the mouth and neck portion of a preform are sandwiched between blow molds and stretched in the longitudinal direction by a stretching rod provided coaxially with a blow pin. No.) etc. are known,
When the blow molding is performed by such a method, there is a drawback that the preform is liable to oscillate due to a vibration phenomenon caused by air pressure blown into the preform, and the hollow container is apt to be uneven in thickness.

【０００４】このような欠点を改良する方法として、予
備成形して延伸成形が可能な温度に加熱したプリフォー
ムを、ブロー金型に口頸部を挟持して、ブローヘッドに
同心状に設けた延伸ロッドにより縦軸方向に延伸させて
からブロー成形する方法（特公昭５３−１９３４４号、
特公昭５８−３７８９５号）や、前記予備成形したプリ
フォームを、ブロー金型に口頸部を挟持した状態でブロ
ー成形すると同時に、プリフォームの底部中央を外側か
らセンターピンで支持して後退させながら成形する方法
（特開昭５７−１９７１２７号）が知られているが、こ
れ等の方法では、射出成形によりプリフォームを成形す
る際に生ずるゲートマークその他に起因した肉厚が不均
一な分布になるのを避けがたく、そして、このようなプ
リフォームを延伸成形しても円周方向における偏肉は解
消しがたくて、製品の強度上の問題だけでなく外観上か
らも好ましくない。[0004] As a method of remedying such a drawback, a preform which has been preformed and heated to a temperature at which stretch forming can be performed is provided concentrically on a blow head by holding a mouth and neck portion in a blow mold. Blow molding after stretching in the longitudinal axis direction by a stretching rod (Japanese Patent Publication No. 53-19344,
Japanese Patent Publication No. 58-37895) and the preformed preform is blow-molded with the mouth and neck held in a blow mold, and at the same time, the center of the bottom of the preform is supported by a center pin from the outside and retracted. A method of molding while performing molding (Japanese Patent Application Laid-Open No. 57-197127) is known. However, in these methods, the distribution of the uneven thickness due to gate marks and the like generated when a preform is molded by injection molding is known. , And even if such a preform is stretch-formed, it is difficult to eliminate uneven thickness in the circumferential direction, which is not only a problem from the viewpoint of the strength of the product but also from the viewpoint of appearance.

【０００５】そこで、上記したようなプリフォームの射
出成形時の肉厚分布の不均一やブロー成形時の横振れに
起因する中空容器の偏肉の発生を防止するようにしたも
のとして、前記予備成形したプリフォームをブロー金型
に口頸部を挟持し、該プリフォームの底部を内側の延伸
ロッドと外側の支持ピンとで保持して、延伸ロッドによ
り縦軸方向に延伸させる同時に、支持ピンを後退させな
がらながらブロー成形する方法がある。（特開昭５２−
７３９６６号）この発明のようにプリフォームの底部を
延伸ロッドと支持ピンとで挟着して固定した状態で、縦
軸方向に延伸すると共にブロー成形することにより、プ
リフォーム成形時の不均一な肉厚分布は分散、緩和され
ると同時に、ブロー空気圧による横方向の揺れも解消さ
れるので、円周方向の偏肉も一応防ぐことができる。In order to prevent the uneven thickness distribution of the hollow container due to the uneven thickness distribution at the time of injection molding of the preform and the lateral deflection at the time of blow molding as described above, the above-mentioned preparatory method has been proposed. The formed preform is sandwiched between the mouth and neck by a blow mold, and the bottom of the preform is held by an inner extending rod and an outer supporting pin. There is a method of performing blow molding while retracting. (Japanese Patent Laid-Open No. 52-
No. 73966) As in the present invention, in a state where the bottom of the preform is fixed by being sandwiched between a stretching rod and a support pin, the preform is stretched in the longitudinal direction and blow-molded, so that a non-uniform meat at the time of preform molding is formed. The thickness distribution is dispersed and alleviated, and at the same time, the lateral sway caused by the blow air pressure is eliminated, so that the circumferential thickness deviation can be prevented for the time being.

【０００６】しかしながら、上記発明に於けるプリフォ
ームの内外から底部を挟着して支持する延伸ロッドと支
持ピンとの先端部は平坦な面に形成されており、また、
延伸ロッドが押圧するプリフォームの底部面で加圧空気
を吹き込むので、プリフォームの状態によっては、延伸
時に延伸ロッドまたは支持ピンが当接したプリフォーム
底部の延伸中心がずれて変位を生じて、ブロー成形した
製品に偏肉を生じて強度や外観上の不都合な点がみられ
たり、また、ブロー成形金型内でブロー成形された中空
容器等の製品は、ブロー圧により製品の表面が成形金型
面に密着していて、製品の底面部が金型面に付着してい
るので取り出し作業が円滑にできないことがあった。[0006] However, the leading ends of the extending rod and the support pin for sandwiching and supporting the bottom from inside and outside of the preform in the above invention are formed on a flat surface.
Since the pressurized air is blown at the bottom surface of the preform pressed by the stretching rod, depending on the state of the preform, the stretching center of the preform bottom contacted by the stretching rod or the support pin at the time of stretching is displaced, resulting in displacement, Blow-molded products may have uneven thickness, causing disadvantages in strength and appearance.In addition, for products such as hollow containers blow-molded in blow molding dies, the surface of the product is formed by blow pressure. Since the product is in close contact with the mold surface and the bottom surface of the product is adhered to the mold surface, the take-out operation may not be performed smoothly.

【０００７】そこで、このような不良点を改善するもの
として図５に示すように、２軸延伸ブロー成形装置に於
いて、プリフォーム４に当接する延伸ロッド５と支持ピ
ン６の先端部にそれぞれ凹溝５ａと突条６ａとからなる
滑り止めの凹凸面を設けて、プリフォームの底部４ａを
内側の延伸ロッドと外側の支持ピンとで挟持して、延伸
ロッドにより延伸させると同時に支持ピンを後退させな
がらながらブロー成形することにより、プリフォーム底
部の延伸中心位置が変位するのを防止したものを考案し
た。（実開昭５８−８４２１６号参照） しかし、上記考案によりＰＥＴ樹脂を２軸延伸ブロー成
形する場合には、成形品にヒートセット等の加熱処理を
施して耐熱性を付与する必要があるので、成形品の底面
部が金型面に付着して製品の取り出し作業が円滑にでき
ないことがあり、また、上記のような凹溝５ａと突条６
ａを形成した延伸ロッドと支持ピンにより挟持してブロ
ー成形すると、成形品の底面部に不規則な凹凸面が形成
されて、傷がついたようになって見栄えが良くないとい
う欠点があった。In order to improve such a defect, as shown in FIG. 5, in a biaxial stretch blow molding apparatus, a tip of a stretching rod 5 and a tip of a support pin 6 which come into contact with a preform 4 are respectively provided. A non-slip uneven surface comprising a concave groove 5a and a ridge 6a is provided, and the bottom 4a of the preform is sandwiched between an inner extending rod and an outer supporting pin, and the supporting pin is retracted while being extended by the extending rod. A device in which the stretching center position of the bottom of the preform is prevented from being displaced by blow molding while performing the molding. (See Japanese Utility Model Application Laid-Open No. 58-84216) However, when biaxially stretch blow-molding a PET resin according to the above invention, it is necessary to apply heat treatment such as heat setting to the molded product to impart heat resistance. In some cases, the bottom surface of the molded product adheres to the surface of the mold, making it difficult to take out the product.
When the blow molding is performed by sandwiching the stretched rod and the support pin formed with a, an irregular uneven surface is formed on the bottom surface of the molded product, and there is a defect that the appearance is not good due to scratches. .

【０００８】従って、上記のような延伸時に於ける延伸
ロッドまたは支持ピンからのプリフォーム底部の延伸中
心が変位するのを防止すると共に、ブロー成形した製品
の成形金型からの離型を円滑にするように改良したもの
として、本願出願人は、実公昭６１−２３３７５号公報
に記載するように、２軸延伸ブロー成形装置に於ける成
形金型の底部に、製品の底部形成する面を有すると共に
軸心部にシリンダ室を設けた底部金型と、該底部金型に
上端部が型面の一部を形成すると共に下端部にピストン
を有する底部支持ピンを、前記シリンダ室内に進退可能
に設けて底部金型部分を形成して、該支持ピンの後退限
界近くで支持ピンに前進方向へ弾性作用をする弾発材を
前記シリンダ室に設けて、延伸ロッドと支持ピンとを一
定間隔に維持して、前進方向に一定抗力に保つようにし
たものを考案した。この方法によれば、ブロー成形した
製品を成形金型面から円滑に離型することはできるが、
しかし、プリフォーム底部４１ａが延伸ロッド５１と支
持ピン６１とで挟持された状態は、図４に示すように平
滑な先端面で挟持されたものであるから、２軸延伸ブロ
ー成形に於ける延伸操作時にプリフォームが横揺れし
て、底部の延伸中心が変位して支持ピン６１の芯ずれを
おこすことがある。Accordingly, it is possible to prevent the center of stretching of the bottom of the preform from the stretching rod or the support pin from being displaced during the stretching, and to smoothly release the blow-molded product from the molding die. As disclosed in Japanese Utility Model Publication No. 61-23375, the applicant of the present invention has a surface on which the bottom of a product is formed at the bottom of a molding die in a biaxial stretch blow molding apparatus. A bottom mold having a cylinder chamber at the shaft center, and a bottom support pin having an upper end forming a part of the mold surface and having a piston at the lower end of the bottom mold. The bottom mold portion is formed to provide a resilient material that elastically acts on the support pin in the forward direction near the retreat limit of the support pin in the cylinder chamber, and maintains the extension rod and the support pin at a constant interval. do it I devised what was kept constant drag in the forward direction. According to this method, the blow-molded product can be smoothly released from the molding die surface,
However, the state in which the preform bottom 41a is sandwiched between the stretching rod 51 and the support pins 61 is a state in which the preform bottom 41a is sandwiched between the smooth tip surfaces as shown in FIG. During operation, the preform may roll laterally, displacing the extension center at the bottom and causing the support pin 61 to be misaligned.

【０００９】[0009]

【発明が解決しようとする課題】本願発明は、ポリエチ
レンテレフタレート等の熱可塑性樹脂を２軸延伸ブロー
成形するに際して、予備成形したプリフォームの底部を
内側の延伸ロッドと外側の支持ピンとで挟持して、延伸
ロッドにより延伸させると同時に支持ピンを後退させな
がらながらブロー成形する延伸時に、延伸ロッドまたは
支持ピンが当接するプリフォーム底部の延伸中心が変位
するのを防止して、ブロー成形品に偏肉が生じないよう
にすると共に、ブロー成形金型内でブロー成形された中
空容器等の製品の表面がブロー圧により成形金型面に密
着したものを円滑に取り出すことを可能にした延伸ブロ
ー成形装置を提供する。SUMMARY OF THE INVENTION In the present invention, when a thermoplastic resin such as polyethylene terephthalate is biaxially stretch blow-molded, the bottom of the preformed preform is sandwiched between an inner stretch rod and an outer support pin. At the time of blow molding while retracting the support pin while being stretched by the stretch rod, the stretch center of the bottom of the preform with which the stretch rod or the support pin abuts is prevented from being displaced, and the thickness of the blow molded product is uneven. Stretch blow molding machine that enables the surface of a product such as a hollow container blow-molded in a blow molding die to be smoothly removed from the surface of the molding die due to the blow pressure. I will provide a.

【００１０】[0010]

【課題を解決するための手段】ブロー成形金型に口頸部
を挟持したプリフォームの底部を内側の延伸ロッドと外
側の支持ピンとで保持して、延伸ロッドにより軸方向に
延伸させる同時に、支持ピンを後退させながらながらブ
ロー成形するポリエチレンテレフタレート等の熱可塑性
樹脂を２軸延伸ブロー成形する装置に於いて、成形金型
の底部に、製品の底部形成する面を有する支持ピンを設
けると共に軸心部にシリンダ室を有する底部型を設け
て、該支持ピンの下端部にピストン部を形成して前記シ
リンダ室内に進退可能に設けて底部金型部分を構成し
て、前記シリンダ室内に、ブロー工程の後退限界近くで
前記支持ピンに前進方向へ弾性作用をする弾発材を設け
ると共に、該支持ピン先端面を断面が凹形状をした円周
縁に形成して安定性を増して、前記延伸ロッドと協働し
てプリフォームの底部の延伸中心が変位しないように保
持可能にする。Means for Solving the Problems The bottom of a preform having its mouth and neck held in a blow molding die is held by an inner stretching rod and an outer support pin, and is stretched in the axial direction by the stretching rod. In an apparatus for biaxially stretch-blow-molding a thermoplastic resin such as polyethylene terephthalate, which is blow-molded while retracting a pin, a support pin having a surface on which a product bottom is formed is provided at the bottom of a molding die, and a shaft center is provided. A bottom mold having a cylinder chamber is provided at a portion thereof, and a piston portion is formed at a lower end portion of the support pin and provided so as to be able to advance and retreat into the cylinder chamber to form a bottom mold portion. Near the retreat limit, the support pin is provided with a resilient material that exerts an elastic action in the forward direction, and the support pin tip surface is formed on a circumferential edge having a concave cross section to improve stability. And, drawing the center of the bottom portion of the preform in cooperation with the stretching rod to be held so as not to be displaced.

【００１１】[0011]

【発明の実施の形態】ポリエチレンテレフタレート樹脂
を射出成形により予備成形したプリフォーム４を、２軸
延伸ブロー成形装置の成形金型１の口頸部２ａに挟持す
ると共に、プリフォームの底部４ａを内側に設けた延伸
ロッド５と外側に設けた先端面６ａが断面凹形状の円周
縁をした支持ピン６とで挟持して、プリフォーム４の延
伸中心が変位しないように保持する。次いで、前記延伸
ロッド５を伸長させてプリフォーム４を縦方向に延伸さ
せる同時に、支持ピン６を後退させながらながら前記プ
リフォーム４内にブロー孔より加圧空気を吹き込んで膨
張成形して円周方向に延伸させる。しかる後、２軸延伸
ブロー成形が完了してから、ブロー圧力を停止して成形
金型を開放せしめると、前記支持ピン６は底部金型３の
シリンダ室３ａ内に設けた弾発材３ｃの反発力により底
部金型３面から突出せしめられて、成形品は底部金型面
から強制的に且つ確実に離型されて２軸延伸ブロー成形
が終了する。DESCRIPTION OF THE PREFERRED EMBODIMENTS A preform 4 preformed by injection molding of polyethylene terephthalate resin is sandwiched between a mouth and neck 2a of a molding die 1 of a biaxial stretch blow molding apparatus, and a bottom 4a of the preform is placed inside. Of the preform 4 is held between a stretching rod 5 provided on the front side and a support pin 6 having a concave cross section and having a circumferential edge so as not to be displaced. Next, the stretching rod 5 is extended to stretch the preform 4 in the vertical direction. At the same time, while the support pins 6 are retracted, pressurized air is blown into the preform 4 from the blow holes to expand and mold. Stretch in the direction. After that, after the biaxial stretch blow molding is completed, when the blow pressure is stopped and the molding die is opened, the support pin 6 is attached to the elastic material 3c provided in the cylinder chamber 3a of the bottom die 3. The repelling force causes the bottom mold 3 to protrude from the bottom mold surface, and the molded product is forcibly and surely released from the bottom mold surface, thereby completing the biaxial stretch blow molding.

【００１２】[0012]

【実施例】以下、図面を参照しつつ本願発明を、最適な
一つの実施例に基づいて詳細に説明する。２軸延伸ブロ
ー成形装置に於ける成形金型１は、半割りの金型１ａと
ブロー芯型２と底部金型３とが組み合わさってブローキ
ャビィティ１ｂが形成されるように構成されている。そ
して、前記ブロー芯型２は、プリフォーム４の開口部に
嵌合して容器の開口首部に合致する口頸部２ａを有し、
その中心部にブロー用の空気孔と延伸ロッド５とを同心
状に設けてなり、該口頸部２ａと前記半割り金型１ａと
でプリフォーム４の開口部を挟持して容器の口頸部を形
成可能に構成されている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings based on one preferred embodiment. The molding die 1 in the biaxial stretch blow molding apparatus is configured such that a half mold 1a, a blow core mold 2, and a bottom mold 3 are combined to form a blow cavity 1b. . The blow core mold 2 has a mouth-neck portion 2a that fits into the opening of the preform 4 and matches the opening neck of the container.
An air hole for blowing and a stretching rod 5 are provided concentrically at the center thereof, and the opening of the preform 4 is sandwiched between the mouth and neck portion 2a and the half mold 1a. It is configured so that a part can be formed.

【００１３】また、前記底部金型３は、中央部に進退可
能な支持ピン６を設けてなり、該支持ピンは、その上端
部６ａに断面が凹形状の円周縁をした成形容器底部の成
形面を形成すると共に下端部にピストン６ａを形成し
て、底部金型３に設けたシリンダ室３ａに嵌入して保持
されて、シリンダ室に形成した吸排気孔３ｂに加圧空気
を供給、排出することにより前進、後退動が可能に構成
されており、前記シリンダ室の下端部内には、コイルス
プリングからなる弾発材３ｃが後退した支持ピン６に前
進方向の弾発力を作用するように組付けられている。The bottom mold 3 is provided with a support pin 6 which can be advanced and retracted at the center, and the support pin is formed at the upper end 6a of the bottom of a molding container having a concave peripheral section. Forming a surface and forming a piston 6a at the lower end, the piston 6a is fitted and held in a cylinder chamber 3a provided in the bottom mold 3, and supplies and discharges pressurized air to an intake / exhaust hole 3b formed in the cylinder chamber. The resilient member 3c made of a coil spring is arranged in the lower end portion of the cylinder chamber so as to act on the retracted support pin 6 to exert a resilient force in the forward direction. It is attached.

【００１４】ポリエチレンテレフタレート樹脂を溶融し
て、射出成形により所定形状をしたプリフォーム４に予
備成形して、該プリフォームを、図１に示すように、ブ
ロー成形装置の成形金型１のブロー芯型２の口頸部２ａ
に嵌合せしめて、成形金型に組み合わせた半割り金型１
ａで挟着すると共に、プリフォームの底部４ａを内側に
設けた前記延伸ロッド５と外側に設けた前記支持ピン６
との間に延伸中心位置が変位しないように保持する。A polyethylene terephthalate resin is melted and preformed into a preform 4 having a predetermined shape by injection molding, and the preform is blow-molded into a blow mold 1 of a blow molding apparatus as shown in FIG. Mouth and neck 2a of mold 2
Half mold 1 combined with the mold
a extending rod 5 provided with the bottom 4a of the preform inside and the support pin 6 provided outside.
Is held so that the stretching center position is not displaced.

【００１５】しかる後に、図２に示すように、前記延伸
ロッド５を伸長させてプリフォーム４を縦方向に延伸さ
せると同時に、前記シリンダ室３ａの上部の供給口３ｂ
に圧搾空気を供給すると共に下部の排気口３ｂからシリ
ンダ室内の加圧空気を排気させて、支持ピンを後退させ
ながらながらブロー口から加圧空気を噴射して膨張せし
めて２軸方向に延伸ブロー成形して中空容器となす。こ
の時、支持ピン６のピストン部６ａは後退限界間近で弾
発材３ｃに当接して後退するので、ブロー終了時には支
持ピン６は弾発材３ｃにより前進方向の反発力を保持し
た状態で底部金型３の中央成形面を形成している。Thereafter, as shown in FIG. 2, the stretching rod 5 is extended to extend the preform 4 in the vertical direction, and at the same time, the supply port 3b at the top of the cylinder chamber 3a is extended.
And pressurized air in the cylinder chamber is exhausted from the lower exhaust port 3b, and while the support pin is retracted, the compressed air is injected from the blow port to expand and expand in the biaxial direction. It is formed into a hollow container. At this time, the piston portion 6a of the support pin 6 comes into contact with the resilient material 3c near the retreat limit and retreats. Therefore, at the end of blowing, the support pin 6 retains the repulsive force in the forward direction by the resilient material 3c. The central molding surface of the mold 3 is formed.

【００１６】上記のようにして延伸ブロー成形された中
空容器は、成形金型内で所定温度にヒートセットされた
り、冷却される等の熱処理操作が施された後、成形金型
１が開放状態にされてブロー芯型２及び延伸ロッド５が
後退すると、支持ピン６は弾発力によりその先端部が僅
かに突出して中空容器の底面を勢いよく押圧するので、
中空容器はブロー成形金型から強制的に確実に離型され
て、２軸延伸ブロー成形操作の工程は終了する。The hollow container stretch blow-molded as described above is subjected to a heat treatment such as heat setting to a predetermined temperature or cooling in the molding die, and then the molding die 1 is opened. When the blow core mold 2 and the extension rod 5 are retracted, the support pin 6 has a slightly protruding tip due to the resilient force and vigorously presses the bottom surface of the hollow container.
The hollow container is forcibly and reliably released from the blow molding die, and the process of the biaxial stretch blow molding operation is completed.

【００１７】上記の説明から明らかなように、本願発明
は、２軸延伸ブロー成形装置に於いて、ブロー成形され
る製品の偏肉を防止するために、ブロー成形金型の底部
金型３部に形成したシリンダ室３ａに進退自在に支持ピ
ン６を嵌入せしめて配置し、該支持ピンの先端面６ａを
断面が凹形状をした円周縁に形成してプリフォーム４の
底部４ａが滑らない程度の抵抗を有しているが、その延
伸ブロー成形時の変形を妨げないようにすると共に、後
退位置では弾発材により前進方向に付勢状態となるよう
にして、該支持ピン先端面とブロー芯型に設けた延伸ロ
ッド先端面とでプリフォーム底部４ａの延伸中心部を挟
持するようにして、ブロー成形時にプリフォームの延伸
中心が変位しないように構成したものである。As is apparent from the above description, the present invention relates to a biaxial stretch blow molding apparatus in which three parts of a bottom mold of a blow molding mold are used in order to prevent uneven thickness of a product to be blow molded. A support pin 6 is fitted and disposed in a freely movable cylinder chamber 3a formed at the end of the preform 4 so that the tip end surface 6a of the support pin 6 is formed at a circumferential edge having a concave cross section so that the bottom 4a of the preform 4 does not slip. However, it does not hinder the deformation during the stretch blow molding, and at the retracted position, is urged in the forward direction by the resilient material so as to be in contact with the front end face of the support pin. The stretching center of the preform bottom 4a is sandwiched between the leading end surface of the stretching rod provided in the core mold and the stretching center of the preform is not displaced during blow molding.

【００１８】このような構成としたことにより、延伸ロ
ッド５の先端面５ａと支持ピン６の先端面６ａとの間に
プリフォーム４の延伸中心となる底部４ａを軽く挟持し
た状態で、支持ピンは延伸ロッドの前進に同期して底部
金型面が滑らかに形成されるまで後退させながら前記プ
リフォームは２軸方向に延伸ブロー成形されるが、図３
に示すように、プリフォームの底部４ａは支持ピン先端
部６ａの断面凹形状の円周縁面でずれないように、且
つ、変形可能に支持されているので、プリフォーム底部
４ａの延伸中心が変位することもなく、また、成形品の
成形金型１からの離型が円滑に達成される。With such a configuration, the support pin is lightly held between the distal end surface 5a of the stretching rod 5 and the distal end surface 6a of the support pin 6 so that the bottom 4a serving as the center of extension of the preform 4 is held therebetween. FIG. 3 shows that the preform is stretch blow-molded in two axial directions while retracting until the bottom mold surface is formed smoothly in synchronization with the advancement of the stretching rod.
As shown in (2), since the preform bottom 4a is supported so as not to be displaced by the circumferential edge surface of the cross-section concave shape of the support pin tip 6a and is deformable, the extension center of the preform bottom 4a is displaced. In addition, the release of the molded product from the molding die 1 is smoothly achieved.

【００１９】上記の構成に於いて、支持ピン先端部に断
面が凹形状となるように円周縁を形成したので、容器の
底部外面に円形状の浅い溝部が形成されるが、円形状に
代えて複数の円弧状に形成してもよい。また、容器の内
面に浅い痕跡があってもよい場合には、延伸ロッドの先
端部に同様な形状を形成してもよく、そのようにすれば
一層プリフォームの延伸中心が変位することはない。
尚、上記の構成に於ける支持ピンの後退限界間近に於け
る弾発材の反発力は、ブロー時の圧力よりも強いもので
あってはならず、弾発材は底部金型面から成形品を離型
させるだけの押圧作用を有すれば充分である。In the above configuration, since the circumferential edge is formed at the tip of the support pin so that the cross section is concave, a shallow circular groove is formed on the outer surface of the bottom of the container. To form a plurality of arcs. In the case where a shallow trace may be present on the inner surface of the container, a similar shape may be formed at the tip of the stretching rod, so that the stretching center of the preform is not further displaced. .
The repulsive force of the resilient material near the retreat limit of the support pin in the above configuration must not be stronger than the pressure at the time of blowing, and the resilient material is formed from the bottom mold surface. It is sufficient to have a pressing action enough to release the product.

【００２０】[0020]

【発明の効果】以上、説明したように、本願発明は、成
形金型内に口頸部を挟持したプリフォームを、内側に設
けた延伸ロッドと外側に設けた支持ピンとで挟着する従
来の２軸延伸ブロー成形する成形装置に於いて、前記支
持ピンの先端部に断面が凹形状をした周縁を設けたこと
により、ブロー成形時にプリフォームの延伸中心が変位
することがない。また、前記支持ピンを進退可能に保持
する底部金型のシリンダ室内に、支持ピンを後退位置で
前進方向に付勢状態となす弾発材を設けたことにより、
成形品を成形金型面から円滑に離型することができる。As described above, according to the present invention, a conventional preform in which a mouth and neck is sandwiched in a molding die is sandwiched between a stretching rod provided inside and a support pin provided outside. In the molding apparatus for biaxially stretch-blow molding, the center of the preform is not displaced during blow molding by providing a peripheral edge having a concave cross section at the tip of the support pin. Further, by providing a resilient material for biasing the support pin in the forward direction at the retracted position in the cylinder chamber of the bottom mold that holds the support pin so as to be able to advance and retreat,
The molded product can be released smoothly from the molding die surface.

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

【図１】本願発明の成形装置にプリフォームを挟持した
ブロー成形直前を示す断面図である。FIG. 1 is a sectional view showing a state immediately before blow molding in which a preform is sandwiched by a molding apparatus of the present invention.

【図２】本願発明の成形装置に於けるブロー成形終了直
前を示した断面図である。FIG. 2 is a cross-sectional view showing a state immediately before the end of blow molding in the molding apparatus of the present invention.

【図３】本願発明に於けるプリフォーム底部の支持状態
の拡大図である。FIG. 3 is an enlarged view of a support state of a preform bottom portion in the present invention.

【図４】先行例に於けるプリフォーム底部の支持状態を
示す断面図である。FIG. 4 is a cross-sectional view showing a support state of a preform bottom portion in a conventional example.

【図５】プリフォーム底部の延伸中心が変位しない支持
形態の先行例である。FIG. 5 is a prior example of a supporting form in which the stretching center at the bottom of the preform is not displaced.

【符号の説明】 １ 成形金型 ２ ブロー芯型 ２ａ 口頸部 ３ 底部金型 ３ａ シリンダ室 ３ｂ 吸排気孔 ３ｃ 弾発材 ４ プリフォーム ４ａ プリフォーム底部 ５ 延伸ロッド ６ 支持ピン[Description of Signs] 1 Molding die 2 Blow core die 2a Mouth and neck 3 Bottom die 3a Cylinder chamber 3b Intake / exhaust hole 3c Resilient material 4 Preform 4a Preform bottom 5 Stretch rod 6 Support pin

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】 半割りの金型本体とブロー芯型と底部金
型とからなるブロー成形金型を備えた熱可塑性剛性樹脂
の２軸延伸ブロー成形装置に於いて、 前記ブロー芯型は、予備成形品の開口部を嵌着する口頸
部を有すると共に、軸心部にブロー孔と延伸ロッドとが
同心状に形成されて、 前記底部金型は、軸心底部にシリンダ室を形成して、先
端面が底部金型の成形面の一部をなすと共に該先端面に
滑り止めを形成し、下端にピストン部を形成した支持ピ
ンを、前記シリンダ室内に延伸ロッドと同期して進退可
能に保持して、且つ、該シリンダ室の支持ピンの後退限
界位置には支持ピンを前進方向に付勢する弾発材が設け
られて、 前記延伸ピンの先端面と支持ピンの先端面との間に、前
記口頸部に嵌着する予備成形品の底部延伸中心を挟持し
た状態を維持してブロー成形を可能としたことを特徴と
する２軸延伸ブロー成形の成形金型装置。1. A biaxial stretch blow molding apparatus for a thermoplastic rigid resin comprising a blow molding mold comprising a half mold body, a blow core mold and a bottom mold, wherein the blow core mold comprises: A blow mold and an extension rod are formed concentrically at the shaft center while having a mouth-and-neck portion for fitting the opening of the preform, and the bottom mold forms a cylinder chamber at the shaft center bottom. The tip surface forms a part of the molding surface of the bottom mold and forms a non-slip on the tip surface, and the support pin having a piston at the lower end can be advanced into and out of the cylinder chamber in synchronization with the extension rod. And a resilient material for urging the support pin in the forward direction is provided at a retreat limit position of the support pin in the cylinder chamber, and a front end surface of the extension pin and a front end surface of the support pin are provided. A state in which the center of the bottom extension of the preform to be fitted to the mouth and neck is sandwiched between A molding apparatus for biaxial stretch blow molding, wherein blow molding is enabled while maintaining the condition. 【請求項２】 前記支持ピンの先端面の滑り止めは、断
面が凹形状をした円周縁に形成したことを特徴とする請
求項１に記載する２軸延伸ブロー成形の成形金型装置。2. A molding die apparatus for biaxial stretch blow molding according to claim 1, wherein the non-slip at the tip end surface of said support pin is formed on a circumferential edge having a concave cross section. 【請求項３】 前記支持ピンの先端面の滑り止めは、断
面が凹形状をした複数の円弧縁に形成したことを特徴と
する請求項１に記載する２軸延伸ブロー成形の成形金型
装置。3. The molding die apparatus for biaxial stretch blow molding according to claim 1, wherein the non-slip of the tip surface of the support pin is formed in a plurality of arc edges having a concave cross section. .
JP8248942A 1996-08-31 1996-08-31 Mold apparatus for biaxial stretching blow molding Pending JPH1071641A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP8248942A JPH1071641A (en) 1996-08-31 1996-08-31 Mold apparatus for biaxial stretching blow molding

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP8248942A JPH1071641A (en) 1996-08-31 1996-08-31 Mold apparatus for biaxial stretching blow molding

Publications (1)

Publication Number Publication Date
JPH1071641A true JPH1071641A (en) 1998-03-17

Family

ID=17185717

Family Applications (1)

Application Number Title Priority Date Filing Date
JP8248942A Pending JPH1071641A (en) 1996-08-31 1996-08-31 Mold apparatus for biaxial stretching blow molding

Country Status (1)

Country Link
JP (1) JPH1071641A (en)

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US9314955B2 (en) 2010-10-15 2016-04-19 Discma Ag Use of optimized piston member for generating peak liquid pressure
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