JPH06218793A - Blow molding method - Google Patents

Abstract

PURPOSE:To change smoothly to a flat or odd-shaped parison from a circular parison, by a method wherein the parison having a circular section is suspended between split molds performing blow molding and made into a flat state or an odd-shaped state by a parison holding device provided on the upper part or the upper part and the lower part of the split molds. CONSTITUTION:A pair of pinch devices are provided on the lower part of a die 9 and an extruded parison 13 is made into a bottomed parison. A pair of parison holding parts 16a, 16b making a circular parison into an elliptic form or an oval form are provided among the pinch devices 14a, 14b and split molds 10a, 10b. The parison 13 is extruded through the die 9 and the bottomed parison 13 is molded by the pinch devices 14a, 14b. After the lower end part of the parison 13 is suspended until it arrives at the lower parts of the molds 10a, 10b, the parison holding parts 16a, 16b are allowed to abut against the parison 13 and the parison 13 is premolded into a flat parison from a circular form. Then the molds 10a, 10b are clamped, blow molding is performed and the holding parts 16a, 16b are restored.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow molding method for obtaining a flat or irregularly shaped parison using a circular die.

[0002]

2. Description of the Related Art When manufacturing flat hollow products such as panels and boards from parisons formed by a blow molding machine, a flat parison is used according to the product rather than a circular parison. Since it is convenient in manufacturing, a blow molding machine that can mold a flat parison has been proposed.

Conventionally, in order to form such a flat parison, a flat die for ejecting a flat parison has been used, or a flat die separated from the lower part of the parison immediately after a true circle parison has been ejected. There is a method of inserting a pair of expander pins into the parison to widen it.

[0004]

However, in the case of the above-mentioned conventional blow molding method, the die is more complicated in structure and more expensive than the true circular die. In addition, in the case of, there was a problem that the parison itself was easily scratched, and further only the lower part of the parison expanded and the upper part remained a perfect circle.

In view of the above-mentioned conventional problems, it is an object of the present invention to provide a blow molding method capable of smoothly changing a circular parison to a flat or irregularly shaped parison.

[0006]

In order to solve such a problem, in the blow molding method according to the present invention, a parison injected in a circular shape from a circular die is hung between the divided molds to divide the divided molds. The parison hanging in between is preformed from a circular shape to a flat shape or an irregular shape by the parison gripping means provided on the upper part or lower part of the split mold, and then the split mold is closed and blown. Molding was performed.

[0007]

After the circular parison is ejected from the circular die, the parison gripping means arranged between the split die and the circular die is actuated to preform the parison from the circular shape to the flat shape, and finally the split die. By closing the mold and performing blow molding, a parison having a desired shape other than a circular shape such as a flat parison can be easily obtained with a circular die.

[0008]

EXAMPLES Specific examples of the blow molding method according to the present invention will be described below in detail with reference to the drawings.

The hollow molding die 10 comprises a pair of split dies 10a and 10b which are separated into right and left as shown in FIGS.
By closing the mold, a cavity portion (cavity portion) 11 whose upper and lower ends are closed is formed in a substantially central portion. The split molds 10a and 10b are mold clamping plates 12 respectively.
It is fixed to a and 12b with a bottle or the like. The hollow molding die 10 is arranged below the die 9 of a molding machine (not shown) and at a position separated from the die 9, and a cavity portion 11 is located substantially directly below the die 9. .

Further, a pair of pinch devices 14 (14) are provided at a lower portion of the die 10 at a position separated from the die 10.
a) and 14b) are arranged horizontally, and the lower portion of the parison 13 extruded from the die 10 is formed into a bag shape to form a bottomed parison 13. Between the pinch device 14 and the split molds 10a and 10b, a preforming device 15 including a pair of parison holding portions 16 is disposed, as in the pinch device 14.

Next, the structure of the preforming apparatus 15 according to the present invention will be described. The parison holding portion 16 as a parison holding means is composed of a pair of left and right parison holding portions 16a and 16b arranged facing each other, and a pair of parison holding portions 16 are brought close to each other with the parison 13 interposed (see FIG. (1)) The contact surface at the time of contact has an elliptical or elliptical shape (FIG. 3 (2)). The parison holder 16 holds the circular parison 13 hanging from the dice 10 from both sides separated from the parison 13 so that the desired flat parison 13 or other irregularly shaped parison 13 (see FIG. )) Is preformed.

The parison holding portion 16 is the die 10
And the split molds 10a and 10b are arranged between the split molds 10a and 10b. As shown in FIG.
Alternatively, the parison 13 may be disposed at a position separated from a and 10b, and the parison 13 may be sandwiched between the parison 13 and the parison 13 to be preformed from the circular parison 13 to the elliptical or elliptical parison 13.

Further, the parison holding portion 16 (16a,
16b) shows the shape of the contact surface between the parison 13 and the parison holding portion 16 when the pair of parison holding portions 16a and 16b are brought into contact with each other with the parison 13 interposed therebetween.
(2) Not only the pair of facing bolts 17 (17
a, 17b) so that the tips of the parison holders 16a, 1b are brought into contact with each other and the bolt 17 is rotated.
The flat shape of the parison 13 may be modified by changing the separation distance between the 6b (FIG. 5 (1)).

Further, the parison holder 16 and the parison 1
The contact surface with 3 may be preformed into a deformed shape as shown in FIG. 5 (2).

The operation of the blow molding machine configured as described above will be described.

First, as shown in FIG. 1 (1), the split mold 1
Keep 0a and 10b open and open the mold,
Pinch devices 14a, 14b and parison holder 16
Leave a and 16b open. Then the dice 9
A little more parison 13 is pushed out and pinch device 1
4a and 14b are approached to the parison 13 and the lower part of the parison 13 is pinched to form the bottomed parison 13 (FIG. 1 (2)).

Next, a circular parison 1 is formed from the dice 9.
3 is suspended until the lower end portion is positioned slightly below the split molds 10a, 10b and stopped, and then the pair of parison holding portions 16a, 16b are brought into contact with each other, the parison 13
Is preformed from a circular shape to an oval or elliptical so-called flat parison 13 (FIG. 2C).

As described above, the circular parison 13 extruded from the die 9 is once preliminarily formed into a flat shape by sandwiching it between the parison holding portions 16, and then the parison 13 is brought into close contact with the split molds 10a and 10b. At the same time, the parison holders 16a and 16b are returned to their original positions and cooled to form a hollow molded body along the cavity 11 (FIG. 2 (4)).

FIG. 4 shows another embodiment similar to the embodiment of the present invention, in which a circular parison 13 extruded from a die 9 is once disposed under the split molds 10a and 10b. Between holding parts 16a and 16b and split mold 1
Parison holding part 16 arranged on the upper part of 0a, 10b
a and 16b are brought into immediate contact with each other almost simultaneously and the parison holding portion 16
If it is sandwiched between a and 16b, the preforming is performed more reliably.

[0020]

As is apparent from the above description, in the blow molding method according to the present invention, the parison injected in a circular shape from the circular die is hung between the divided dies, and the parison is hung between the divided dies. The parison is preformed from a circular shape to a flat shape or a different shape by the parison holding means provided on the upper part of the split mold or on the upper and lower parts of the split mold.
Next, the split mold is closed and blow molding is performed, so that a flat parison can be easily obtained with the circular die. In addition, by simply changing the parison holder, it is possible to easily obtain a parison with a different aspect ratio (ratio of major axis and minor axis) and a different shape.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a blow molding before a mold clamping when a parison cage according to the present invention is used.

FIG. 2 is an explanatory view at the time of mold clamping of blow molding when the parison cage according to the present invention is used.

FIG. 3 is an explanatory view showing a deformed state of the parison when it is clamped by the parison holder.

FIG. 4 is a diagram showing another embodiment similar to the embodiment of the present invention.

FIG. 5 is an explanatory view showing another embodiment of the parison cage similar to the embodiment of the present invention.

[Explanation of symbols]

 9 dies 10 hollow molding dies 10a, 10b split dies 11 cavities 12a, 12b mold clamping plates 13 parisons 14 (14a, 14b) pinch devices 15 preforming devices 16 (16a, 16b) parison holders

Claims (1)

[Claims] 1. A parison in which a parison ejected in a circular shape from a circular die is hung between divided dies, and the parison hung between the divided dies is provided above the divided dies or above and below the divided dies. A blow molding method, characterized in that preforming is performed from a circular shape to a flat shape or an irregular shape by a gripping means, and then the split mold is closed to perform blow molding.