JPH0659685B2 - Molding method for plastic hollow body - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic hollow body composed of a front surface and a back surface facing each other and side surfaces formed around them, such as a panel-shaped building member and a vehicle member such as a spoiler. The present invention relates to a method for molding a hollow plastic body by blow molding.

Conventional technology Conventionally, a parison is hung between a pair of split molds, the molds are clamped and blow molded, and then the split molds are opened to obtain a hollow molded product. It is practiced as a manufacturing means for automobile members such as car and spoiler, and various hollow body members.

Further, in blow molding of a hollow plastic body, as a method of using a blow molding die having a structure in which a pinch offline is provided on one side of a side surface of a molded product, it is described in, for example, Japanese Utility Model Publication No. 57-88524. Things are known.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the conventional method for molding a plastic hollow body as described above, a pinch offline is formed on a surface parallel to the mold opening direction of the molded product. If it is a panel-shaped one, it is formed around the side surface, so it is often noticeable and the appearance is often impaired, which requires complicated work for finishing the molded product.

Therefore, as described in Japanese Utility Model Application Laid-Open No. 57-88524, the method of using a blow molding die having a structure in which the pinch off-line is eccentrically arranged on one side of the side surface of the molded product is used. Although it is possible to move it to one side of the side surface, it is not possible to form a hollow body whose side surface appearance is also important depending on the type of hollow body.

Therefore, the present invention provides one of the divided molds having a cavity for shaping the shape of the front and side surfaces of the plastic hollow body, and the other of the other having a cavity for shaping the shape of the back surface of the plastic hollow body inside A pair of split molds including a split mold and a cavity for shaping a part of the side surface and the back surface of the plastic hollow body inside, and integrated with one of the split molds. By using an auxiliary mold as a mold, the pinch offline that occurs during blow molding is formed on the back side that is not visible,
Molding of plastic hollow bodies that not only surface but also side appearance can be obtained, and finishing work of pinch offline can be omitted. It is intended to provide a method.

Means for Solving the Problems The present invention achieves the object by the following means, and the means are as follows.

In a method of blow molding a plastic hollow body consisting of a front surface and a back surface facing each other and side surfaces formed around them, one split mold having a cavity for shaping the surface and side surfaces of the plastic hollow body inside And a pair of split molds each having a cavity for shaping the shape of the back surface of the plastic hollow body inside, and a pair of split molds inside and a part of the side surface and the back surface of the plastic hollow body. Using an auxiliary die that has a cavity for shaping the shape and is combined with one of the above divided dies to form an integrated die, and the auxiliary die is combined with one of the divided dies to form an integrated die At the same time, after opening the integrated mold and the other split mold and hanging a parison between them, the integrated mold and the other split mold are clamped and blow molded, one Characterized in that the mold is opened between the chemical mold and the other split mold, and then the auxiliary mold constituting the integrated mold is moved in a direction orthogonal to the mold opening direction to release the molded product. Method for molding a hollow plastic body.

According to the method for molding a plastic hollow body according to the present invention,
As a mold for blow molding a hollow plastic body, a sub-mold that has a cavity inside the plastic hollow body to shape part of the sides and back surface of the plastic hollow body and combines it with one split mold to form an integrated mold. Since we use a mold,
At the time of blow molding in which the mold is closed, the pinch offline is located on the back surface side of the molded product by the integrated auxiliary mold, and the pinch offline is formed on the back surface side of the molded product. Then, after molding, the integrated mold and the other split mold are opened, and then the auxiliary mold constituting the integrated mold is moved in a direction orthogonal to the mold opening direction, so that the back surface side It is possible to release the molded product on which the pinch offline is formed.

Embodiment An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a panel-shaped hollow body as a molded product formed by the method for molding a plastic hollow body according to the present invention. Reference numeral 1 is the front surface, 2 is the back surface, and 3 is the side surface, and the pinch off-line 4 that is generated in the cutout portion of the hollow body during blow molding is formed in the peripheral portion on the back surface 2 side.
It does not appear on side 3. 5 is Bali, this Bali 5
Are removed after molding.

FIG. 2 illustrates a mold used for carrying out the method according to the present invention.

Reference numerals 6 and 6 ′ are a pair of split molds, and one of the split molds 6 has a surface 1 and a side surface 2 of a plastic hollow body inside.
And a cavity 7'for shaping the shape of the back surface 2 of the hollow plastic body inside the other split mold 6 '. Reference numeral 8 is an auxiliary mold, and this auxiliary mold 8 is vertically divided into two parts, each of which is vertically movable. The auxiliary metal mold 8 has a cavity for shaping a part of the side surface 3 and the back surface 2 of the plastic hollow body inside, and the one of the divided metal molds 6 is formed.
This is an integrated mold together with.

As shown in FIGS. 3 to 6, the cavity of the auxiliary mold 8 has a surface 8a which is parallel to the mold opening direction and a surface 8b which is orthogonal to the mold opening direction. Part of the cavity 7 is formed, and the pinch offline 4
Is shaped so as to approach the back surface 2 side of the hollow body.

In the figure, A indicates the mold opening direction of the pair of split molds 6 and 6 ', and B indicates the moving direction of the auxiliary mold 8.

At the time of blow molding of the hollow plastic body, the auxiliary mold 8 is fitted to one of the divided molds 6 to form an integrated mold, and the integrated mold and the other divided mold 7'are opened. , A thermoplastics parison 9 extruded from an extruding head (not shown) is hung between them, and the integrated die and the other divided die 7'are clamped and blow-molded. Tighten and blow mold as shown in FIG. Then, after blow molding, the integrated mold and the other split mold 6'are opened in the direction of arrow A as shown in FIG. 5, and the auxiliary mold 8 is shown as arrow B orthogonal to the mold opening direction as shown in FIG. When the molded product is released by moving it in the direction, a panel-shaped hollow body as shown in FIG. 1 is obtained.

The hollow pinch offline 4 molded in this way is
Since it is formed on the peripheral portion of the back surface 2 of the hollow body and does not appear on the side surface 3 and is inconspicuous in use, it is often unnecessary to carry out finishing work such as shaving the pinch offline 4, and the finishing work is required. Greatly simplified.

The auxiliary mold 8 can be divided into two parts in the vertical direction B, which is orthogonal to the mold opening direction, by means of a device such as a hydraulic cylinder, and can also be divided into four parts in the vertical direction (not shown) for synchronous movement with the mold opening. . The auxiliary mold 8 may be opened before the split molds 6 and 6'are opened or at the same time.

In the above-mentioned embodiment, the pinch off-line is formed on the back surface 2 of the hollow body which is not visible, but it is also possible to form the pinch off-line only on the upper and lower parts of the hollow body. In the case of a spoiler or other automobile member, a pinch off line may be formed on the mounting surface.

EFFECTS OF THE INVENTION According to the present invention, as a mold for blow molding a plastic hollow body, it has a cavity for shaping a part of the side surface and the back surface of the plastic hollow body inside, and is combined with one split mold. Since an integrated mold consisting of an auxiliary mold is used, it is possible to form a plastic hollow body with excellent appearance by forming the pinch offline that occurs during blow molding on the back side that is invisible. The processing work can be simplified.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is a perspective view of a formed plastic hollow body, FIG. 2 is a perspective view of a mold, and FIGS. FIG. 1 ... Front of hollow body, 2 ... Back surface, 3 ... Side surface, 4 ...
Pinch off-line, 5 ... Burr, 6, 6 '... Pair of split molds, 7, 7' ... Cavity, 8 ... Auxiliary mold, 8
a: surface parallel to mold opening direction, 8b: surface orthogonal to mold opening direction, 9: burr

Claims (1)

[Claims] 1. A method of blow-molding a hollow plastic body comprising front and back surfaces facing each other and side surfaces formed around the front and back surfaces, wherein a cavity for shaping the shape of the front and side surfaces of the hollow plastic body is provided inside. A pair of split molds including one split mold and the other split mold having a cavity for shaping the shape of the back surface of the plastic hollow body, a side surface of the plastic hollow body, and Uses an auxiliary mold that has a cavity that shapes a part of the back surface and is combined with one of the above-mentioned split molds to form an integrated mold. Along with constructing a chemical mold, open the integrated mold and the other split mold, hang a parison between them, and clamp the integrated mold and the other split mold. Blow blow After that, the integrated mold and the other divided mold are opened, and then the auxiliary mold constituting the integrated mold is moved in the direction orthogonal to the mold opening direction to release the molded product. A method for molding a plastic hollow body, which is characterized by the above.