JPS59136218A - Vacuum forming method - Google Patents

Abstract

PURPOSE:To make possible successful forming of deeply drawn or complex configuration with equal thickness by dividing the vacuum part of thermoplastic synthetic resin sheet into multiple portions vacuum-forming those portions successively. CONSTITUTION:A thermoplastic resin sheet 4 set on a mold 3 is heated and softened and then, a portion 3a which is severest in deep drawing and complexity of configuration and hardest in formability in the mold 3 is made vacuous first of all and attached to the vacuum-forming surface for this portion 3a to take a desired configuration. Then, a portion 3b which is medium in deep drawing or complexity of configuration is made vacuous to take a desired configuration and last of all, a portion 3c which is least in deep drawing or complexity of configuration, then the thermoplastic resin sheet is cooled, vacuum drawing is stopped to release the formed piece from the mold. Forming defects due to short vacuum pressure do not occur and equal thickness is obtained in the deeply drawn portion or the portion of complex configuration.

Description

【発明の詳細な説明】 （発明の分野） 本発明は、塩化ビニル樹脂、アクリロニトリル−ブタジ
ェン−スチレン樹脂、エチレン−酢酸ビニル共重合体等
の熱可塑性合成樹脂シートの成形に用いられる真空成形
法に関する。DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to a vacuum forming method used for forming thermoplastic synthetic resin sheets such as vinyl chloride resin, acrylonitrile-butadiene-styrene resin, and ethylene-vinyl acetate copolymer. .

（従来技術の説明） 真空成形法は、熱可塑性合成樹脂シートの熱成形法のう
ち、最も広く行なわれている方法で、シートを型の上に
保持したまま加熱軟化でせ、型とシートとの間隙を真空
にして、シートを型に密着形法は、成形圧力が１ｋＱ／
ｃ４以下なので、成形機、型等が安価であり、大型品や
薄物品の成形に適している。従って、自動車内装部品、
家具等に用いられるクッション体のカバーから卵や豆腐
の包装容器の成形に至るまで広範囲に亘って利用されて
いる。(Description of Prior Art) Vacuum forming is the most widely used method of thermoforming thermoplastic synthetic resin sheets, and is a method in which the sheet is heated and softened while being held on the mold, and the mold and sheet are bonded together. In the molding method where the gap is vacuumed and the sheet is closely attached to the mold, the molding pressure is 1kQ/
Since it is less than c4, molding machines, molds, etc. are inexpensive, and it is suitable for molding large and thin products. Therefore, automobile interior parts,
It is used in a wide range of applications, from the covers of cushion bodies used in furniture, etc. to the molding of packaging containers for eggs and tofu.

この真空成形法は、雄型成形と雌型成形の二種類に大別
され、前者は、加熱軟化したシートを雄型上に予張した
後真空成形する方法であるために、深絞りに適しており
、後者は、加熱軟化したシートを単に真空によって雌型
に直接吸いつけて成形する方法であるために、深絞りゃ
形状の複雑な成形には好ましくないものでおった。しか
し、求められる形状によっては雌型成形によらねばなら
すや 改良が求められてた。第１図の断面図は、雌型成形が深
絞りの成形には適さないことを説明する図である。真空
成形型１上にセットされた熱可塑性合成樹脂シート２は
、加熱軟化でれた後、真空成形型の真空成形面１ａと熱
可塑性合成樹脂シート２との空間′ｆＩ：典突にするこ
とによって、真空成形型の真空成形部１ａに密着し、所
定形状とされる。This vacuum forming method is roughly divided into two types: male die forming and female die forming.The former is suitable for deep drawing because it involves pre-stretching a heat-softened sheet onto a male die and then vacuum forming it. The latter method is a method in which a heat-softened sheet is simply drawn directly into a female mold using a vacuum, and therefore is not suitable for forming complex deep-drawn shapes. However, depending on the desired shape, female molding may have to be used, and improvements have been required. The cross-sectional view in FIG. 1 is a diagram explaining that female molding is not suitable for deep drawing. After the thermoplastic synthetic resin sheet 2 set on the vacuum forming mold 1 is heated and softened, the space between the vacuum molding surface 1a of the vacuum forming mold and the thermoplastic synthetic resin sheet 2 is made into a space 'fI: straight. As a result, it is brought into close contact with the vacuum forming part 1a of the vacuum forming mold to form a predetermined shape.

この熱可塑性合成樹脂シート２の真空成形型の真ｂ 空成形面１ａへの吸引は、真空吸引穴特を介して、矢印
に示す如くの真空吸引により深絞り部分ａと他の部分す
、ｃとにおいて同時になされるために吸引の容易な部分
、すなわち深絞りでない部分ｂＣへの密着が初めに行な
われ、この後深絞り部分ａへの吸引ＶＢ着が行なわれる
。したがって、深絞り部分ａに対応する熱可塑性合成樹
脂シー）２ａは他部分より大きく伸びねばならず、この
ためにこの部分においては大きな真空吸引力が必要とな
り、深絞りの程度によっては成形できなかった。The thermoplastic synthetic resin sheet 2 is sucked into the vacuum molding surface 1a of the vacuum molding die by vacuum suction as shown by the arrows through the vacuum suction holes to the deep drawn portion a and other portions A, C. Since this is done at the same time, the part where suction is easy, that is, the part bC which is not deep drawn, is first closely attached, and then the suction VB is attached to the deep drawn part a. Therefore, the thermoplastic synthetic resin sheet 2a corresponding to the deep drawing part a must stretch more than the other parts, and for this reason, a large vacuum suction force is required in this part, and depending on the degree of deep drawing, it cannot be formed. Ta.

更に、辛うじて深絞りが形成された場合においても、熱
可塑性合成樹脂シートのこの深絞り部分の厚みは極端に
薄くなり、梨地等の模様を鮮明に付与することができな
かった。これと同様のことは、凹凸等の多い複雑な形状
の成形においても生じていた。Furthermore, even when deep drawing is barely formed, the thickness of the deep drawing portion of the thermoplastic synthetic resin sheet becomes extremely thin, making it impossible to clearly impart a pattern such as satin finish. A similar problem also occurred when molding a complex shape with many irregularities.

（発明の目的） 本発明は、深絞り及び複雑な形状の成形を可能とし、且
つ、深絞り部分における鮮明な模様の付与を可能とする
真空成形法を与えるものである。(Objective of the Invention) The present invention provides a vacuum forming method that enables deep drawing and molding into a complicated shape, and also enables the provision of a clear pattern in the deep drawn portion.

（発明の構成） 第２図乃至第４図は、本発明に係る真空成形法の概略工
程図である。(Structure of the Invention) FIGS. 2 to 4 are schematic process diagrams of the vacuum forming method according to the present invention.

本発明の実施に用いられる成形型は、真空成形部が複数
の部分に分けられ、各部分が独立して真空吸引可能とさ
れたものであり、この成形型の一実施例６は、最も成形
が困難である、深絞り又は形状の複雑度が最大である部
分３　ａ　ｓ幾分成形が困難である、深絞り又は形状の
複雑度が中程度である部分３ｂ、最も成形が容易である
、深絞り又は形状の複雑度が最小の部分６０を各々別個
に真空吸引可能とする構造である。勿論、求められる真
空成形の形状によっては、更に細かく区分される場合も
あるが、説明を容易にするために、本説明においては、
３ａ、３ａ、３ｂ、３ｂ、３０の五区分された成形型を
用いて記す。尚、成形型は真空成形面の裏側の真空部を
、図示した箱形状に限るものではなく、真空吸引用のパ
イプを設けたもの、その他としてもよい。The mold used to carry out the present invention has a vacuum forming section divided into a plurality of parts, each of which can be vacuum-suctioned independently. Part 3a, which is difficult to deep draw or have the greatest degree of shape complexity Part 3a, which is somewhat difficult to form, part 3B, which has medium degree of deep drawing or shape complexity, is the easiest to form. The structure allows the deep drawing or the parts 60 with the least complexity of shape to be vacuum-sucked separately. Of course, depending on the desired shape of vacuum forming, there may be more detailed classifications, but in order to make the explanation easier, in this explanation,
The description will be made using molds divided into five sections: 3a, 3a, 3b, 3b, and 30. Note that the vacuum part on the back side of the vacuum molding surface of the mold is not limited to the box shape shown in the figure, but may be provided with a pipe for vacuum suction, or may have another shape.

本発明は、熱可塑性合成樹脂シートの真空成形部を複数
の部分に区分し、各部分を順次真空成形するものであり
、以下、添付図面を用いて本発明の一実施例を詳述する
。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a vacuum-formed portion of a thermoplastic synthetic resin sheet is divided into a plurality of parts, and each part is successively vacuum-formed.One embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

イ、ｆＲ絞り又は形状の複雑度が最大である、成形が最
も困難な部分の成形（第２図） 成形型６上にセット式れた熱可塑性合成樹脂シート４は
、加熱軟化された後、成形型６の深絞り又は形状の複雑
度が最も大きく成形が最も困難な部分３ａを真空吸引す
ることにより、この部分３ａの真空成形面に密着し、所
定形状とされ名。B. Molding of the part where the fR drawing or shape complexity is the greatest and is the most difficult to mold (Fig. 2) After the thermoplastic synthetic resin sheet 4 set on the mold 6 is heated and softened, By deep drawing the mold 6 or by vacuum suctioning the part 3a, which has the greatest degree of complexity in shape and is the most difficult to mold, the part 3a is brought into close contact with the vacuum molded surface and formed into a predetermined shape.

口、深絞り又は形状の複雑度が中程度で、幾分成形が困
難な部分の成形（第６図） 成形型３の深絞り又は形状の複雑度が中程度で、幾分成
形が困難な部分３ｂを真空吸引することにより、この部
分６ｂの成形型の真空成形面に熱可塑性合成樹脂シート
４を密着させ、所定形状とする。Deep drawing of the mold 3 or forming of a part with a medium complexity of shape and somewhat difficult to form (Fig. 6) By applying vacuum suction to the portion 3b, the thermoplastic synthetic resin sheet 4 is brought into close contact with the vacuum molding surface of the mold for this portion 6b, and a predetermined shape is formed.

成形が最も容易な部分６Ｃｆ：、真空吸引することによ
り、この部分６Ｃの成形型の真空成形面に熱可塑性合成
樹脂シート４を密着させ、所定形状とする。Portion 6Cf that is easiest to mold: By vacuum suction, the thermoplastic synthetic resin sheet 4 is brought into close contact with the vacuum molding surface of the mold for this portion 6C to form a predetermined shape.

この後熱可塑性樹脂シートを冷却し、真空吸引を止め、
成形品を脱型する。After this, the thermoplastic resin sheet is cooled, the vacuum suction is stopped,
Demold the molded product.

尚、前記の３ａ、　６ｂ、　６ａの部分は、成形の雌易
度を最大要因として決定される。Note that the above-mentioned portions 3a, 6b, and 6a are determined with the ease of molding as the biggest factor.

成形型の真空成形面には、必要に応じて梨地等の模様が
刻設される。A pattern such as satin finish is engraved on the vacuum molding surface of the mold, if necessary.

（発明の効果） 本発明に係る真空成形法は、熱可塑性合成樹脂シートの
Ｘ突成形部を複数の部分に区分し、深絞り又は形状の複
雑度あるいはこれらの両者が最も大きく、成形が最も困
難な部分から真空成形を始め、順次、深絞り又は形状の
複雑度が小となる、より成形が容易な部分の真空成形を
行なうものである。すなわち、従来の成形法において大
きな伸びが必要とされた部分から真空成形を行なうもの
である。この様に、熱可塑性合成樹脂シートが最も引き
伸ばされ易い時点、つまり一番初めに最も伸びを必要と
する部分を真空成形し、順次、伸びの必要度が小となる
部分の真空成形へと移行するものである。したがって、
従来の成形方法において見られた様な、深絞り部分又は
形状が複雑な部分における真空吸引力不足による成形不
良を生じることがない。更に、本発明の成形方法は、従
来においては最も引き伸ばされていた、深絞り部分又は
形状が複雑な部分から真空成形を行なうものであるため
に、この部分が他部分と比較して厚みがそれ程薄くなら
ず、梨地等の模様も明確に付与することができるととも
に、厚みも均一となり、この厚みの均一化により、クッ
ション体に本発明により成形したシートを装着した際に
、厚み差による部分的な硬度差がなくなり、使用感が良
好となる。(Effects of the Invention) The vacuum forming method according to the present invention divides the X-projection forming part of a thermoplastic synthetic resin sheet into a plurality of parts, and divides the X-projection forming part of a thermoplastic synthetic resin sheet into a plurality of parts. Vacuum forming is started from the difficult part, and then deep drawing or vacuum forming is performed on the part that is easier to form, where the complexity of the shape is smaller. In other words, vacuum forming is performed starting from the parts where large elongation was required in conventional forming methods. In this way, the thermoplastic synthetic resin sheet is vacuum-formed at the point where it is most easily stretched, that is, the part that requires the most elongation, and then the vacuum-formed parts are gradually moved to the parts that require less elongation. It is something to do. therefore,
There is no possibility of molding defects due to insufficient vacuum suction force in deep-drawn parts or parts with complicated shapes, as seen in conventional molding methods. Furthermore, since the forming method of the present invention performs vacuum forming from the deep drawn part or the part with a complicated shape, which was conventionally stretched the most, this part is not as thick as other parts. It does not become thin, and patterns such as satin finish can be clearly applied, and the thickness becomes uniform.As a result of this uniform thickness, when the sheet formed according to the present invention is attached to a cushion body, there will be no unevenness due to the difference in thickness. There is no difference in hardness, and the usability is improved.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は従来の真空成形法を」？、明する断面図、第２
図乃至第４図は本発明に係る真空成形法の概略工程を示
す断面図である。Figure 1 shows the conventional vacuum forming method. , a cross-sectional view showing the second
4 through 4 are cross-sectional views showing schematic steps of the vacuum forming method according to the present invention.

Claims (1)

【特許請求の範囲】 １、熱可塑性合成樹脂シートを、深絞り形状又は複雑な
形状、あるいはこれらの両者の形状を有する所定形状に
真空成形する際に、該熱可塑性合成樹脂シートの真壁成
形部を複数の部分に区分し、各部分を順次真突成形する
ことを特徴とする真空成形法。 ２、深絞り又は形状の複雑度、あるいはこれらの両者の
程度が大の部分から小の部分へと順次真空成形すること
を特徴とする特許請求の範囲第１項記載の真空成形法。[Scope of Claims] 1. When vacuum forming a thermoplastic synthetic resin sheet into a predetermined shape having a deep drawing shape, a complicated shape, or both of these shapes, a straight wall forming portion of the thermoplastic synthetic resin sheet A vacuum forming method characterized by dividing the material into multiple parts and sequentially forming each part in a straight-edge manner. 2. The vacuum forming method according to claim 1, characterized in that vacuum forming is carried out sequentially from parts with a large degree of deep drawing or complexity of shape, or both, to parts with a small degree.