JPH10272646A - Method and device for manufacturing hollow molded item - Google Patents

Method and device for manufacturing hollow molded item

Info

Publication number
JPH10272646A
JPH10272646A JP7984697A JP7984697A JPH10272646A JP H10272646 A JPH10272646 A JP H10272646A JP 7984697 A JP7984697 A JP 7984697A JP 7984697 A JP7984697 A JP 7984697A JP H10272646 A JPH10272646 A JP H10272646A
Authority
JP
Japan
Prior art keywords
synthetic resin
molten synthetic
gas
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.)
Granted
Application number
JP7984697A
Other languages
Japanese (ja)
Other versions
JP3276880B2 (en
Inventor
Atsushi Fukuhara
敦志 福原
Kazuaki Nakabayashi
和昭 中林
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.)
Itoki Crebio Corp
Original Assignee
Itoki Crebio Corp
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 Itoki Crebio Corp filed Critical Itoki Crebio Corp
Priority to JP7984697A priority Critical patent/JP3276880B2/en
Publication of JPH10272646A publication Critical patent/JPH10272646A/en
Application granted granted Critical
Publication of JP3276880B2 publication Critical patent/JP3276880B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related 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
    • 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
    • B29C45/1704—Introducing an auxiliary fluid into the mould the fluid being introduced into the interior of the injected material which is still in a molten state, e.g. for producing hollow articles

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)

Abstract

PROBLEM TO BE SOLVED: To achieve reduction in machining cost of a die, improved durability of a device, and high manufacturing efficiencies when a hollow molded item is manufactured by a gas-aided injection molding method. SOLUTION: While a molten synthetic resin R is being injected into a cavity 13, gas is blown off from nozzles 17, 18, 19 in the order of increasing distance from an injection port 15 to inject the resin R in an expanded form. Even if the pressure of the gas is relatively low, e.g. 20-30 kg/cm<2> , the resin R can be molded into a hollow shape easily and surely, and hence manufacturing and maintenance costs of device can be reduced and durability and manufacturing efficiency can be improved.

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、ガス支援射出成形
法によって製造される中空成形体の製造方法並びに製造
用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 a method for producing a hollow molded article produced by a gas-assisted injection molding method and a mold apparatus for producing the same.

【０００２】[0002]

【従来の技術】ガス支援射出成形法は、密着・離反自在
な一対の金型の合わせ面に形成したキャビティに、溶融
合成樹脂を、キャビティの容積よりも少ない量（例えば
キャビティの容積の50〜80％程度）だけ注入し、次い
で、溶融合成樹脂を注入し切ってから、キャビティ内に
窒素ガス等のガスを噴出させて、溶融合成樹脂をキャビ
ティの内面に押し付けることによって中空成形体を製造
するものである。2. Description of the Related Art In a gas-assisted injection molding method, a molten synthetic resin is filled in a cavity formed in a mating surface of a pair of molds that can be brought into close contact with and separated from each other, in an amount smaller than the volume of the cavity (for example, 50 to 50 times the cavity volume). (About 80%), then inject the molten synthetic resin completely, and then blow out a gas such as nitrogen gas into the cavity, and press the molten synthetic resin against the inner surface of the cavity to produce a hollow molded body. Things.

【０００３】この成形法によると、例えばポリプロピレ
ンのような安価な素材を使用して、単純な断面形状で強
度の高い中空成形体を製造できる利点がある。このた
め、例えば椅子用脚体のように、従来は６ナイロンや66
ナイロン等のエンジニアリングプラスチックを素材とし
て射出成形法で製造していた物品に適用すると、コスト
ダウンが可能になる。According to this molding method, there is an advantage that a hollow molded body having a simple sectional shape and high strength can be manufactured using an inexpensive material such as polypropylene. For this reason, conventionally, for example, 6 nylon or 66
When applied to an article manufactured by an injection molding method using an engineering plastic such as nylon as a material, the cost can be reduced.

【０００４】[0004]

【発明が解決しようとする課題】しかし、従来の一般的
なガス支援射出成形法は、ガスを500 Kg/cm2程度の高圧
で噴出させることによって溶融合成樹脂を中空に膨らま
せるものであるため、シール性の点から金型を高い寸法
精度で加工しなければならないばかりか耐久性も低く、
しかも、ガスの圧縮機等も堅牢な構造にせねばならず、
このためコストダウンの効果を十分に享受できないとい
う問題があった。更に、成形サイクルが長くなるため、
製造能率が悪いと言う問題もあった。However, the conventional general gas assisted injection molding method injects a gas at a high pressure of about 500 Kg / cm 2 to expand a molten synthetic resin into a hollow space. In addition, the mold must be machined with high dimensional accuracy from the viewpoint of sealing properties, and the durability is low.
In addition, the gas compressor must have a robust structure,
Therefore, there is a problem that the effect of cost reduction cannot be sufficiently enjoyed. Furthermore, since the molding cycle becomes longer,
There was also a problem that manufacturing efficiency was poor.

【０００５】本発明は、この問題を解消した製法及び装
置を提供することを目的とするものである。An object of the present invention is to provide a manufacturing method and an apparatus which solve this problem.

【０００６】[0006]

【課題を解決するための手段】このため本発明の製造方
法は、請求項１に記載したように、「密着・離反自在で
且つ合わせ面にキャビティを形成した一対の金型を使用
して、両金型を密着させた状態でキャビティ内に注入口
から溶融合成樹脂を未充満の状態に注入し、この溶融合
成樹脂を、両金型のうちいずれか一方又は両方に設けた
ノズルからキャビティ内に噴出させたガスによって中空
状に膨らませるようにした中空成形体の製造方法におい
て、前記溶融合成樹脂の注入途中にガスをキャビティ内
に噴出させて、溶融合成樹脂をキャビティに注入しつつ
中空状に膨らませる」の構成にした。Therefore, according to the manufacturing method of the present invention, as described in claim 1, "a pair of dies having a cavity formed in a mating surface which can be in close contact with and separated from each other are used. With both molds in close contact with each other, the molten synthetic resin is injected into an unfilled state from the injection port into the cavity, and the molten synthetic resin is injected into the cavity from a nozzle provided in one or both of the two molds. In the method for producing a hollow molded body, the gas is blown into the cavity during the injection of the molten synthetic resin, and the molten synthetic resin is injected into the cavity. Inflate ".

【０００７】他方、本発明の製造装置は、請求項２に記
載したように、「密着・離反自在で且つ合わせ面にキャ
ビティを形成した一対の金型を備えており、両金型のい
ずれか一方又は両方に、キャビティに溶融合成樹脂を注
入するための注入口を設けると共に、キャビティ内にガ
スを噴出させるためのノズルを、注入途中の溶融合成樹
脂で覆われるようにして配置し、このノズルからのガス
の噴出と前記注入口からの溶融合成樹脂の注入とを、注
入途中の溶融合成樹脂がノズルの箇所まで到達したら、
溶融合成樹脂の注入口を続けながらノズルからガスを噴
出させるように制御する」の構成にした。On the other hand, the manufacturing apparatus according to the present invention comprises a pair of dies having a cavity formed in a mating surface, which are capable of being in close contact with and separated from each other. On one or both sides, an injection port for injecting the molten synthetic resin into the cavity is provided, and a nozzle for injecting gas into the cavity is arranged so as to be covered with the molten synthetic resin in the middle of the injection. Spout of gas from and injection of the molten synthetic resin from the injection port, when the molten synthetic resin during the injection reaches the location of the nozzle,
Control so that the gas is ejected from the nozzle while continuing the injection port of the molten synthetic resin. "

【０００８】更に製造装置のより好適な形態として、請
求項３に記載したように、「複数個のノズルを、注入口
から遠ざかる方向に沿って適宜隔てて配置し、これらの
ノズルからのガスの噴出と注入口からの溶融合成樹脂の
注入とを、溶融合成樹脂が注入口からキャビティ内に拡
散していくのに連れて、注入口に近いノズルから遠いノ
ズルに向けて順にガスを噴出させるように制御する」の
構成にした。[0008] Further, as a more preferable form of the manufacturing apparatus, as described in claim 3, "a plurality of nozzles are arranged at appropriate intervals in a direction away from the injection port, and gas from these nozzles is discharged. As the molten synthetic resin diffuses into the cavity from the injection port and the injection of the molten synthetic resin from the injection port, the gas is sequentially emitted from a nozzle near the injection port to a nozzle far from the injection port. Control ".

【０００９】[0009]

【発明の作用・効果】従来のように溶融合成樹脂を所定
量だけキャビティ内に注入し切ってからガスを噴出させ
る方法では、所定量注入し切るまで時間が経過すること
によって溶融合成樹脂の流動性が低くなっており、しか
も、溶融合成樹脂を所定量だけ注入し切っているため溶
融合成樹脂を延び変形させるに際しての抵抗も大きく、
このため従来は、ガスを500 Kg/cm2程度の高圧で噴出さ
せて溶融合成樹脂を強引に押し広げていた。In the conventional method of injecting a predetermined amount of the molten synthetic resin into the cavity and then ejecting the gas as in the conventional method, the flow of the molten synthetic resin is caused by the lapse of time until the predetermined amount of the synthetic resin is completely injected. Resistance is low, and since the molten synthetic resin has been injected only by a predetermined amount, the resistance when extending and deforming the molten synthetic resin is large,
For this reason, conventionally, a gas was ejected at a high pressure of about 500 Kg / cm 2 to forcibly spread the molten synthetic resin.

【００１０】更に、溶融合成樹脂がキャビティに流れ込
むと、キャビティの内面に接触した箇所がすぐに硬化し
て薄いスキン層ができるが、溶融合成樹脂を所定量だけ
注入し切るまでガスの噴出を待機しているとスキン層が
発達するため、ガスの圧力を500 Kg/cm2程度の高圧で噴
出させないとスキン層を突き破ることができないのであ
った。Furthermore, when the molten synthetic resin flows into the cavity, the portion in contact with the inner surface of the cavity is immediately cured to form a thin skin layer, but the gas injection waits until a predetermined amount of the molten synthetic resin is completely injected. The skin layer develops when it is pressed, so the gas cannot be pierced through the skin layer unless it is jetted at a high pressure of about 500 Kg / cm 2 .

【００１１】これに対して本発明のように溶融合成樹脂
の注入途中でガスを噴出させると、溶融合成樹脂の流動
性が高い状態で当該溶融合成樹脂を膨らませることがで
きることと、溶融合成樹脂を押し広げるに際しての溶融
合成樹脂の抵抗を著しく低減できること、及びスキン層
が発達する前に溶融合成樹脂Ｒを押し広げ形成できるこ
ととが相まって、ガスの噴出圧力が20〜30Kg/cm2程度の
低圧であっても、溶融合成樹脂を膨らませて中空成形体
を製造することができる。On the other hand, when a gas is ejected during the injection of the molten synthetic resin as in the present invention, the molten synthetic resin can be expanded in a state where the flowability of the molten synthetic resin is high, and The ability to significantly reduce the resistance of the molten synthetic resin when spreading and the ability to spread and form the molten synthetic resin R before the skin layer develops, resulting in a low gas ejection pressure of about 20 to 30 kg / cm 2. Even in this case, the hollow molded article can be manufactured by expanding the molten synthetic resin.

【００１２】従って本発明によると、ガスの噴出圧力が
低くても中空成形体を製造できるため、金型の加工コス
ト等の設備費のの軽減と耐久性向上を図ることができる
と共に、ガスの噴出系統の機器の加工コスト低減と耐久
性向上を図ることができ、その結果、中空成形体の製造
コストを低減できる効果を有する。また、成形サイクル
を短くできるから、製造能率も向上できる。Therefore, according to the present invention, a hollow molded body can be manufactured even if the gas ejection pressure is low, so that equipment costs such as processing costs of a mold can be reduced and durability can be improved. It is possible to reduce the processing cost and improve the durability of the equipment of the ejection system, and as a result, there is an effect that the manufacturing cost of the hollow molded body can be reduced. Further, since the molding cycle can be shortened, the production efficiency can be improved.

【００１３】特に、請求項３のように、溶融合成樹脂を
キャビティに注入しながら複数のノズルから順次ガスを
噴出させる構成にすると、溶融合成樹脂を注入しながら
膨らませることを容易に行うことができる。[0013] In particular, if the gas is ejected sequentially from a plurality of nozzles while injecting the molten synthetic resin into the cavity, it is easy to inflate the molten synthetic resin while injecting it. it can.

【００１４】[0014]

【発明の実施形態】次に、本発明の実施形態を図面に基
づいて説明する。図１〜図８で示すのは本発明を椅子の
脚体に適用した第１実施形態であり、このうち図１は椅
子１の斜視図である。この椅子１は、座体２と中空成形
体の一例としての脚体３とを備えており、脚体３は、中
央に位置した上向き開口の筒部４と、筒部４から放射状
に延びる５本の棒状水平部５とから成っている。各棒状
水平部５の先端にはキャスター６を取付けている。図示
していないが、脚体３の筒部４にはガスシリンダ等の脚
柱を取付けており、これを蛇腹状のカバー７で覆ってい
る。Next, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 to 8 show a first embodiment in which the present invention is applied to a leg of a chair. FIG. 1 is a perspective view of the chair 1. The chair 1 includes a seat body 2 and a leg 3 as an example of a hollow molded body. The leg 3 has an upwardly opening tubular portion 4 located at the center and a radially extending 5 from the tubular portion 4. And a horizontal bar portion 5 of a book. A caster 6 is attached to the tip of each bar-shaped horizontal portion 5. Although not shown, a column such as a gas cylinder is attached to the cylindrical portion 4 of the leg 3, and this is covered with a bellows-like cover 7.

【００１５】図２は脚体３の部分平断面図、図３は脚体
３における棒状水平部５の破断斜視図である。両図に示
すように、各棒状水平部５は中空状に形成されており、
その底板の内面には、平面視で棒状水平部５の中心線に
沿って略全長にわたって延びるリブ８を突設している。
各リブ８は断面合掌状に形成されて、その付け根箇所を
閉じた状態になっている。このため、棒状水平部５の下
面には、リブ８の閉塞面の線９が直線状に延びている。
なお、リブ８は隙間なく完全に密着させた形態でも良
い。FIG. 2 is a partial plan sectional view of the leg 3, and FIG. 3 is a cutaway perspective view of the bar-shaped horizontal portion 5 of the leg 3. As shown in both figures, each bar-shaped horizontal portion 5 is formed in a hollow shape,
On the inner surface of the bottom plate, there is provided a rib 8 which extends over substantially the entire length along the center line of the bar-shaped horizontal portion 5 in plan view.
Each of the ribs 8 is formed in the shape of a cross section and has a closed base portion. For this reason, on the lower surface of the rod-shaped horizontal portion 5, the line 9 of the closing surface of the rib 8 extends linearly.
The ribs 8 may be completely adhered without any gap.

【００１６】このように、各棒状水平部５が中空である
ため、ポリプロピレンのような安価な素材製であって
も、高強度に製造できる。次に、図４〜図８に基づいて
脚体３の製法及び製造用金型装置を説明する。図4(A)は
金型装置と脚体３との分離断面図、図4(B)は(A) のB-B
視底面図、図4(C)は(A) のC-C 視平面図である。金型装
置は、脚体３に上方から嵌まる形状の上金型10と、脚体
３に下方から嵌まる形状の下金型11とを備えている。上
金型10の中心部には中子14を設け、これに溶融合成樹脂
Ｒの注入口（ゲート）15を下向き開口させている。な
お、筒部４は上下に開口させても良い。As described above, since each bar-shaped horizontal portion 5 is hollow, it can be manufactured with high strength even if it is made of an inexpensive material such as polypropylene. Next, a method of manufacturing the leg 3 and a manufacturing die apparatus will be described with reference to FIGS. FIG. 4 (A) is a cross-sectional view of the mold device and the leg 3 separated, and FIG. 4 (B) is the BB of FIG.
FIG. 4 (C) is a plan view in CC of FIG. 4 (A). The mold device includes an upper mold 10 having a shape fitted into the leg 3 from above, and a lower mold 11 having a shape fitted into the leg 3 from below. A core 14 is provided at the center of the upper mold 10, and an injection port (gate) 15 for the molten synthetic resin R is opened downward in the core 14. In addition, you may open the cylinder part 4 up and down.

【００１７】両金型10,11 の合わせ面には、筒部４を成
形するための筒部成形用キャビティ12と、棒状水平部５
を成形するための棒状水平部成形用キャビティ13とを凹
み形成している。下金型11のうち各棒状水平部成形用キ
ャビティ13の箇所には、前記リブ８を成形するための板
状の可動コア16を、棒状水平部成形用キャビティ13に向
けて突出・後退動自在となるように装着している。On the mating surfaces of the two dies 10, 11, a cavity 12 for molding the cylinder 4 for molding the cylinder 4 and a horizontal bar 5 are formed.
And a cavity 13 for molding a rod-shaped horizontal portion for molding the same. A plate-shaped movable core 16 for forming the rib 8 is freely protruded and retractable toward the rod-shaped horizontal portion forming cavity 13 at the position of each rod-shaped horizontal portion forming cavity 13 in the lower mold 11. It is attached so that it becomes.

【００１８】前記各可動コア16には、ガスを棒状水平部
成形用キャビティ13内に噴出させるための第１〜第３の
３本のノズル17,18,19を埋設している。第１〜第３のノ
ズル17,18,19は、各可動コア16の長手方向に沿って、す
なわち、注入口15から順次遠ざかるように適宜間隔を隔
てて並んでいる。各ノズル17,18,19は可動コア16の上端
面から若干突出させている。なお、ノズルの個数は３個
ずつには限らず、必要に応じて任意に設定できることは
言うまでもない。Each of the movable cores 16 has embedded therein first to third nozzles 17, 18, and 19 for ejecting gas into the rod-shaped horizontal portion forming cavity 13. The first to third nozzles 17, 18, 19 are arranged along the longitudinal direction of each movable core 16, that is, at an appropriate interval so as to gradually move away from the inlet 15. Each nozzle 17, 18, 19 slightly protrudes from the upper end surface of the movable core 16. It is needless to say that the number of nozzles is not limited to three, and can be set arbitrarily as needed.

【００１９】図５のうち(A) は図4(C)のV-V 視断面図、
(B) は(A) の平面図である。なお、各ノズル17,18,19を
可動コア16に対して相対的に後退・突出動するように取
付けても良い。また、コア16は下金型11に固定しても良
い。5A is a sectional view taken along the line VV of FIG.
(B) is a plan view of (A). The nozzles 17, 18, and 19 may be mounted so as to retreat and project relative to the movable core 16. Further, the core 16 may be fixed to the lower mold 11.

【００２０】下金型11のうち各棒状水平部成形用キャビ
ティ13の先端に位置した部位には、脚体３の各棒状水平
部５にキャスター取付け穴24を形成するためのピン25を
突設している。更に、下金型11の筒部成形用キャビティ
12のうち棒状水平部成形用キャビティ13の股部には、そ
れぞれ仕切体26を上向きに突設している。各仕切体26は
板状に形成されており（棒状でも良い）、上金型10との
間に若干の隙間が空くような高さ寸法に設定している。
また、各仕切り体26は筒部成形用キャビティ12の外周縁
よりも若干内側に配置している。成形した後の脚体３の
筒部４には、仕切り体26が抜けた後の穴27が空く。A pin 25 for forming a caster mounting hole 24 in each bar-shaped horizontal portion 5 of the leg 3 is protruded from a portion of the lower die 11 located at the tip of each bar-shaped horizontal portion forming cavity 13. doing. Further, the cavity for forming the cylindrical portion of the lower mold 11 is formed.
In the crotch portion of the rod-shaped horizontal portion forming cavity 13 among the 12, a partition member 26 is provided to project upward. Each partition member 26 is formed in a plate shape (or may be a bar shape), and is set to have a height such that a slight gap is left between the partition member 26 and the upper mold 10.
Further, each partition member 26 is disposed slightly inside the outer peripheral edge of the cylindrical portion forming cavity 12. In the cylindrical portion 4 of the leg 3 after molding, a hole 27 is formed after the partition 26 has come off.

【００２１】図６〜７は脚体３の製造工程を示す図、図
８は樹脂の注入とガスの噴出との関係を模式的に示す説
明図であり、これらの図に基づいて、脚体３の製造（成
形）工程を説明する。先ず、図６に示すように、可動コ
ア16を突出させた状態で上下金型10,11 を密着させ、そ
の状態で中子14の注入口15から、ポリプロピレン等の溶
融合成樹脂Ｒを例えば一般の射出成形法の圧力で射出す
る。全体の射出量は、キャビティ12,13 全体の容量の例
えば50〜70％程度である。注入口15から射出された溶融
合成樹脂Ｒは、筒部成形用キャビティ12を通じて各棒状
水平部成形用キャビティ13に流入し、各棒状水平部成形
用キャビティ13の先端に向けて流れていく。FIGS. 6 and 7 are views showing a manufacturing process of the leg 3, and FIG. 8 is an explanatory view schematically showing a relationship between resin injection and gas ejection. The manufacturing (molding) process of No. 3 will be described. First, as shown in FIG. 6, the upper and lower molds 10, 11 are brought into close contact with the movable core 16 protruding, and in this state, a molten synthetic resin R such as polypropylene Injection at the pressure of the injection molding method. The total injection amount is, for example, about 50 to 70% of the entire capacity of the cavities 12 and 13. The molten synthetic resin R injected from the injection port 15 flows into each rod-shaped horizontal portion forming cavity 13 through the cylindrical portion forming cavity 12, and flows toward the tip of each rod-shaped horizontal portion forming cavity 13.

【００２２】そこで、溶融合成樹脂Ｒが各棒状水平部成
形用キャビティ13に注入される過程において、実線ａで
示すように溶融合成樹脂Ｒが第１ノズル17を通過したら
第１ノズル17からガスを噴出させ、一点鎖線ｂで示すよ
うに溶融合成樹脂Ｒが第２ノズル18を通過したら第２ノ
ズル18からガスを噴出させ、二点鎖線ｃで示すように溶
融合成樹脂Ｒが第３ノズル19を通過したら第３ノズル19
からガスを噴出させると言うように、溶融合成樹脂Ｒの
流れに合わせて各ノズル17,18,19からガスを順次噴出さ
せる。Therefore, in the process of injecting the molten synthetic resin R into each rod-shaped horizontal portion forming cavity 13, when the molten synthetic resin R passes through the first nozzle 17 as shown by a solid line a, gas is discharged from the first nozzle 17. When the molten synthetic resin R passes through the second nozzle 18 as indicated by a dashed line b, gas is ejected from the second nozzle 18 and the molten synthetic resin R causes the third nozzle 19 to be ejected as indicated by a two-dot chain line c. After passing, the third nozzle 19
The gas is sequentially ejected from each of the nozzles 17, 18, and 19 in accordance with the flow of the molten synthetic resin R.

【００２３】すると、図８の実線の中空ループａ’、一
点鎖線の中空ループｂ’、二点鎖線の中空ループｃ’に
示すように、溶融合成樹脂Ｒは、中空状に押し広げられ
ながら棒状水平部成形用キャビティ13に充満していく。
これにより、棒状水平部５が中空状に成形される。とこ
ろで、図８のグラフに示すように、溶融合成樹脂Ｒの注
入過程において、当該溶融合成樹脂Ｒの圧力は注入口15
からの距離が遠ざかるほど低くなり、且つ、時間が経過
するに従って（溶融合成樹脂Ｒが充満していくに従っ
て）圧力は高くなっていく。従って、棒状水平部成形用
キャビティ13での圧力分布は、図８のグラフに実線ｄ、
一点鎖線ｅ、二点鎖線ｆで示すようにシフトしていく。
つまり、各ノズル17,18,19の箇所での圧力は、溶融合成
樹脂Ｒの流入量と共に変化していく。Then, as shown in a hollow loop a 'of a solid line, a hollow loop b' of a one-dot chain line, and a hollow loop c 'of a two-dot chain line in FIG. The horizontal portion forming cavity 13 is filled.
Thereby, the bar-shaped horizontal portion 5 is formed into a hollow shape. By the way, as shown in the graph of FIG. 8, during the injection process of the molten synthetic resin R, the pressure of the molten synthetic resin
And the pressure increases as the time elapses (as the molten synthetic resin R fills). Accordingly, the pressure distribution in the rod-shaped horizontal portion forming cavity 13 is represented by a solid line d in the graph of FIG.
The shift is performed as indicated by the one-dot chain line e and the two-dot chain line f.
That is, the pressures at the nozzles 17, 18, and 19 change with the inflow of the molten synthetic resin R.

【００２４】そこで、各ノズル17,18,19からガスを噴出
させるに当たって、ガスの噴出圧力P0が各ノズル17,18,
19の箇所での溶融合成樹脂Ｒの圧力P1〜P3よりも低くな
るように設定する。すなわち、PO＜(P1,P2,P3)の関係に
設定する。例えば溶融合成樹脂Ｒの圧力が40〜100Kg/cm
2の場合、ガスの圧力P0を20〜30Kg/cm2程度に設定す
る。Therefore, when the gas is ejected from each of the nozzles 17, 18, 19, the ejection pressure P0 of the gas is reduced by the respective nozzles 17, 18, and 19.
The pressure is set so as to be lower than the pressures P1 to P3 of the molten synthetic resin R at the 19 points. That is, the relationship of PO <(P1, P2, P3) is set. For example, the pressure of the molten synthetic resin R is 40 to 100 kg / cm.
In the case of 2 , the gas pressure P0 is set to about 20 to 30 kg / cm 2 .

【００２５】このようにして各ノズル17,18,19からガス
を順次噴出させることにより、ガスの圧力が低くても、
スキン層が発達する前に溶融合成樹脂Ｒを能率良く且つ
正確に押し広げ変形させることができる。本実施形態の
ように下金型型11に可動コア16を設けると、溶融合成樹
脂Ｒが可動コア16を包む状態になり、これによってリブ
８が形成される。この場合、樹脂Ｒが硬化し切ってから
型抜きするとリブ８は下向き開口した状態になる。これ
に対して本実施形態では、金型10,11 に冷却水を通して
樹脂Ｒを硬化させる過程で、リブ８の箇所だけがまだ十
分に硬化し切らずに他の部位は概ね硬化した状態で可動
コア16を後退させる。すると、リブ８は、棒状水平部５
の収縮に伴う内部応力により、図３のような形態に閉じ
変形する。By sequentially ejecting gas from each of the nozzles 17, 18, and 19 in this manner, even if the gas pressure is low,
The molten synthetic resin R can be efficiently and accurately expanded and deformed before the skin layer develops. When the movable core 16 is provided in the lower mold 11 as in the present embodiment, the molten synthetic resin R wraps around the movable core 16, thereby forming the rib 8. In this case, when the mold is removed after the resin R is completely cured, the rib 8 is in a state of opening downward. On the other hand, in the present embodiment, in the process of hardening the resin R by passing the cooling water through the molds 10 and 11, only the portion of the rib 8 has not sufficiently hardened yet, and the other portions are movable in a substantially hardened state. The core 16 is retracted. Then, the rib 8 becomes the rod-shaped horizontal portion 5.
Due to the internal stress caused by the shrinkage, the shape is closed and deformed as shown in FIG.

【００２６】つまり、樹脂Ｒの熱は金型10,11 を通して
吸収されるから、各棒状水平部５は金型10,11 に密着し
た外面部分が先に硬化し、リブ８の部分が最も遅く硬化
するため、棒状水平部５には、これを内向きに窄まらせ
るような内部応力が発生し、これにより、リブ８が閉じ
変形するのである。脚体３の全体が硬化したら、両金型
10,11 を離反して型抜きして、脚体３を得る。That is, since the heat of the resin R is absorbed through the molds 10 and 11, the outer surfaces of the respective bar-shaped horizontal portions 5 which are in close contact with the molds 10 and 11 are cured first, and the ribs 8 are the slowest. Due to the hardening, an internal stress is generated in the rod-shaped horizontal portion 5 so as to constrict it inward, whereby the rib 8 is closed and deformed. When the entire leg 3 is hardened,
10 and 11 are separated and die-cut to obtain the leg 3.

【００２７】本実施形態のように、筒部成形用キャビテ
ィ14に仕切体25を突設すると、各棒状水平部成形用キャ
ビティ13内にガスを噴出させたとき、隣合った棒状水平
部成形用キャビティ13間に溶融合成樹脂Ｒが流れ移動す
ることが阻止されるため、各棒状水平部５の肉厚を均一
化できる利点がある。図9(A)は、棒状水平部成形用キャ
ビティ13に１個のノズル30でガスを噴出させるようにし
た第２実施形態を模式的に示したものである。この場
合、溶融合成樹脂Ｒがノズル30の箇所に到達したら、そ
のあとノズル30からガスを噴出し続けても良いし、(B)
のグラフに実線ｇで示すように、間欠的にガスを噴出さ
せても良い。更に、グラフに点線ｈで示すように、ガス
を間欠的に噴出させるにおいて噴出圧力を変化させても
良い。ガスを噴出し続ける場合においても、ガスの噴出
圧力を変化させても良い。また、前記第１実施形態にお
いて、各ノズル17,18,19からのガスの噴出圧力を異なら
せても良い。As in the present embodiment, when the partition member 25 is protruded from the cylindrical portion forming cavity 14, when the gas is blown into each rod-shaped horizontal portion forming cavity 13, the adjacent rod-shaped horizontal portion forming cavity 13 is formed. Since the molten synthetic resin R is prevented from flowing between the cavities 13, there is an advantage that the thickness of each bar-shaped horizontal portion 5 can be made uniform. FIG. 9 (A) schematically shows a second embodiment in which a single nozzle 30 is used to eject gas into the rod-shaped horizontal portion forming cavity 13. In this case, when the molten synthetic resin R reaches the position of the nozzle 30, the gas may be continuously ejected from the nozzle 30 after that, or (B)
As shown by the solid line g in the graph, the gas may be ejected intermittently. Further, as indicated by a dotted line h in the graph, the ejection pressure may be changed in intermittently ejecting the gas. Even when the gas is continuously ejected, the gas ejection pressure may be changed. In the first embodiment, the pressure at which the gas is ejected from each of the nozzles 17, 18, 19 may be made different.

【００２８】図10に示すのは、椅子用脚体３における棒
状水平部５にリブ８を設けるにおいて、リブ８を棒状水
平部５の上下両面まで連接した第３実施形態である。こ
の場合は、ノズル31は可動コア16を挟んだ両側に１個ず
つ又は複数個ずつ設けている。なお、棒状水平部５には
必ずしもリブ８を設ける必要がないこと、及び、リブ８
を設ける場合、その形態は種々に設定できることは言う
までもない。FIG. 10 shows a third embodiment in which a rib 8 is provided on the bar-shaped horizontal portion 5 of the chair leg 3 and the rib 8 is connected to both upper and lower surfaces of the bar-shaped horizontal portion 5. In this case, one or more nozzles 31 are provided on both sides of the movable core 16. In addition, it is not always necessary to provide the ribs 8 in the bar-shaped horizontal portion 5;
Needless to say, in the case where is provided, the form can be variously set.

【００２９】図11に示すのは、ガスの噴出形態の別例で
ある第４実施形態である。この実施形態では、第１〜第
３ノズル17,18,19を設けて、第１ノズル17からガスを順
次噴出させるようにした場合において、樹脂が中空状に
変形し、しかも樹脂Ｒが硬化し切らない前に第１及び第
３のノズル17,19 を後退させ、その状態で第２ノズル18
からのみガスを噴出させるようにしたものである。この
ようにすると、第１ノズル17と第 3ノズル19とが抜けた
後の穴を塞ぐことが可能となる。FIG. 11 shows a fourth embodiment which is another example of the gas ejection mode. In this embodiment, when the first to third nozzles 17, 18, and 19 are provided and the gas is sequentially ejected from the first nozzle 17, the resin is deformed into a hollow shape, and the resin R is cured. Before cutting, the first and third nozzles 17 and 19 are retracted.
The gas is ejected only from the air. By doing so, it becomes possible to close the hole after the first nozzle 17 and the third nozzle 19 have come off.

【００３０】以上の各実施形態は椅子の脚体３に適用し
た場合であったが、本発明は、例えば図12(A) に示す机
の中空状脚体32や中空状天板33、図12(B) に示す中空板
34、図12(C) に示す二重床用の中空フロアーパネル35な
ど、種々の中空成形体の製法と成形装置に適用できる。Although each of the above embodiments is applied to the leg 3 of the chair, the present invention is, for example, a hollow leg 32 or a hollow top plate 33 of a desk shown in FIG. Hollow plate shown in Fig. 12 (B)
34, such as a hollow floor panel 35 for a double floor shown in FIG.

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

【図１】第１実施形態に係る脚体を使用した椅子の斜視
図である。FIG. 1 is a perspective view of a chair using a leg according to a first embodiment.

【図２】脚体の平断面図である。FIG. 2 is a plan sectional view of a leg.

【図３】脚体における棒状水平部の部分斜視図である。FIG. 3 is a partial perspective view of a bar-shaped horizontal portion of the leg.

【図４】(A) は金型装置及び脚体の分離断面図、(B) は
(A) のB-B 視底面図、(C) は(A) のC-C 視平面図であ
る。FIG. 4 (A) is an exploded sectional view of a mold device and a leg, and FIG.
(A) is a bottom view in BB view, and (C) is a plan view in CC view of (A).

【図５】(A) は図4(A)のV-V 視断面図、(B) は(A) の平
面図である。5 (A) is a sectional view taken along the line VV of FIG. 4 (A), and FIG. 5 (B) is a plan view of FIG. 4 (A).

【図６】成形工程を示す断面図である。FIG. 6 is a cross-sectional view showing a molding step.

【図７】成形工程を示す断面図である。FIG. 7 is a cross-sectional view showing a molding step.

【図８】成形工程での樹脂とガスとの関係を示す図であ
る。FIG. 8 is a diagram showing a relationship between resin and gas in a molding step.

【図９】第２実施形態を示す図である。FIG. 9 is a diagram showing a second embodiment.

【図１０】第３実施形態の断面図である。FIG. 10 is a sectional view of a third embodiment.

【図１１】第４実施形態の断面図である。FIG. 11 is a sectional view of a fourth embodiment.

【図１２】本発明を適用できる物品の別例を示す図であ
る。FIG. 12 is a diagram showing another example of an article to which the present invention can be applied.

【符号の説明】[Explanation of symbols]

３ 中空成形体の一例としての椅子用脚体 ５ 脚体の棒状水平部 ８ リブ 10,11 金型 13 棒状水平部成形用キャビティ 15 注入口（ゲート） 16 可動コア 17,18,19 ノズル 3 Leg for chair as an example of hollow molded body 5 Horizontal rod-shaped part of leg 8 Rib 10,11 Mold 13 Cavity for molding horizontal rod-shaped part 15 Inlet (gate) 16 Movable core 17,18,19 Nozzle

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】密着・離反自在で且つ合わせ面にキャビテ
ィを形成した一対の金型を使用して、両金型を密着させ
た状態でキャビティ内に注入口から溶融合成樹脂を未充
満の状態に注入し、この溶融合成樹脂を、両金型のうち
いずれか一方又は両方に設けたノズルからキャビティ内
に噴出させたガスによって中空状に膨らませるようにし
た中空成形体の製造方法において、 前記溶融合成樹脂の注入途中にガスをキャビティ内に噴
出させて、溶融合成樹脂をキャビティに注入しつつ中空
状に膨らませることを特徴とする中空成形体の製造方
法。1. A state in which a molten synthetic resin is not filled from an injection port into a cavity in a state in which both molds are brought into close contact with each other by using a pair of molds having a cavity formed in a mating surface, which can be freely contacted and separated. In the method for producing a hollow molded body, the molten synthetic resin is blown into a hollow shape by a gas ejected into a cavity from a nozzle provided in one or both of the molds, A method for producing a hollow molded body, characterized in that a gas is blown into a cavity during injection of a molten synthetic resin, and the molten synthetic resin is expanded into a hollow shape while being injected into the cavity. 【請求項２】「請求項１」に使用する製造装置であっ
て、密着・離反自在で且つ合わせ面にキャビティを形成
した一対の金型を備えており、両金型のいずれか一方又
は両方に、キャビティに溶融合成樹脂を注入するための
注入口を設けると共に、キャビティ内にガスを噴出させ
るためのノズルを、注入途中の溶融合成樹脂で覆われる
ようにして配置し、このノズルからのガスの噴出と前記
注入口からの溶融合成樹脂の注入とを、注入途中の溶融
合成樹脂がノズルの箇所まで到達したら、溶融合成樹脂
の注入口を続けながらノズルからガスを噴出させるよう
に制御していることをを特徴とする中空成形体の製造装
置。2. A manufacturing apparatus according to claim 1, comprising a pair of dies having a cavity formed in a mating surface which can be in close contact with and separated from each other, and one or both of both dies. In addition, an injection port for injecting the molten synthetic resin into the cavity is provided, and a nozzle for ejecting gas into the cavity is arranged so as to be covered with the molten synthetic resin in the middle of injection, and the gas from this nozzle is disposed. The injection of the molten synthetic resin from the injection port and the injection of the molten synthetic resin, when the molten synthetic resin in the middle of the injection reaches the location of the nozzle, while controlling the injection of the gas from the nozzle while continuing the injection port of the molten synthetic resin, An apparatus for manufacturing a hollow molded article, comprising: 【請求項３】「請求項２」において、複数個のノズル
を、注入口から遠ざかる方向に沿って適宜隔てて配置
し、これらのノズルからのガスの噴出と注入口からの溶
融合成樹脂の注入とを、溶融合成樹脂が注入口からキャ
ビティ内に拡散していくのに連れて、注入口に近いノズ
ルから遠いノズルに向けて順にガスを噴出させるように
制御していることを特徴とする中空成形体の製造装置。3. A method according to claim 2, wherein a plurality of nozzles are arranged at appropriate intervals in a direction away from the injection port, and a gas is injected from these nozzles and a molten synthetic resin is injected from the injection port. The hollow is characterized in that as the molten synthetic resin is diffused into the cavity from the injection port, the gas is ejected in order from a nozzle near the injection port to a nozzle far from the injection port. Manufacturing equipment for moldings.
JP7984697A 1997-03-31 1997-03-31 Method and apparatus for manufacturing hollow molded article Expired - Fee Related JP3276880B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP7984697A JP3276880B2 (en) 1997-03-31 1997-03-31 Method and apparatus for manufacturing hollow molded article

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP7984697A JP3276880B2 (en) 1997-03-31 1997-03-31 Method and apparatus for manufacturing hollow molded article

Publications (2)

Publication Number Publication Date
JPH10272646A true JPH10272646A (en) 1998-10-13
JP3276880B2 JP3276880B2 (en) 2002-04-22

Family

ID=13701576

Family Applications (1)

Application Number Title Priority Date Filing Date
JP7984697A Expired - Fee Related JP3276880B2 (en) 1997-03-31 1997-03-31 Method and apparatus for manufacturing hollow molded article

Country Status (1)

Country Link
JP (1) JP3276880B2 (en)

Also Published As

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JP3276880B2 (en) 2002-04-22

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