JPS621522A - Blow molding device - Google Patents

Abstract

PURPOSE:To constitute the title device so that parison does not swelling out of a mold and flowability of the parison can be held favorably by controlling lowering of the temperature of a discharge part of an extrusion die, by fitting a head part of the tip of the extrusion die in a fitting hole of a split mold through a heat insulation material. CONSTITUTION:When an extrusion die 16is made to descend down to a predetermined position, parison 20 is made to face on a cavity 12 by discharging the parison 20 through a parison discharge hole 18 and mold close of a split mold 11 is performed, air seal of the split mold is performed by holding the external circumferential surface of a head part of the tip of the extrusion die 16 by placing the same between the internal circumferential surface of a fitting hole 13 based on each of recessed parts of the split mold 11 through a heat insulation material 14, and the lower end part of the parison 20 is cut off by pressing the same by placing the same between the split mold 11. Molding is performed by blowing air into the parison through an air blowing hole 19 under this state. As a temperature drop of the extrusion die 16 is mitigated drastically deterioration in fluidity of an outlet part of the parison 20 is controlled and when air is blown in through the inner circumferential surface of the fitting hole 13 and a slit 15 of the external circumferential surface of the heat insulation material 14 the air which has remained between the parison 20 and the inside of the cavity 12 is discharged outside.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to blow molding of synthetic resin products! ! About i@”
Ru.

[Conventional technology]

Conventionally, when blow molding synthetic resin products, the fourth
As shown in the figure, an extrusion die 3 is placed above the proportioning die 2 in which the cavity 1 is formed, and the tip head 4 of the extrusion die 3 is
An annular parison discharge hole 5 is provided on the lower surface of the parison discharge hole 5, and an air blowing pin 6 is protruded from the center of the parison discharge hole 5.
The upper end of the parison 7 extruded from the parison discharge hole 5 is pinched and cut off by the split die 2, and the air blowing pin 6 is held between the split die 2 and the air blowing pin 6 is inserted into the parison 7. It is molded by blowing air into it.

However, in such blow molding equipment, bending or breakage of the air blowing pin frequently occurs, and production is often interrupted to repair or replace the pin.

For this reason, a blow molding apparatus without an air blowing pin as shown in FIG. 5 has been proposed. That is, while a through hole 1a is formed in the upper part of the cavity 1 of the split die 2, an annular parison discharge hole 5 is formed in the lower surface of the tip head 4 of the extrusion die 3, and an air blowing hole is formed in the center of the parison discharge hole 5. A filling hole 6a is formed, the parison 7 extruded from the parison discharge hole 5 is introduced into the cavity 1 of the split mold 2, the mold is closed, and the lower end of the parison 7 is pinched by the split mold 2 and cut off. At the same time, the extrusion die 3 is lowered to bring the lower surface of the tip head 4 into close contact with the upper surface of the split mold 2, and air is blown into the parison 7 through the air blowing hole 6a of the extrusion die 3 to form the parison.

[Problem that the invention seeks to solve]

However, with the device shown in Fig. 5 of E) above, the seal between the split mold and the extrusion die is insufficient, and the parison bulges out of the split mold during air blowing, leading to punctures. There is also the problem that heat from the parison discharge port of the extrusion die is taken away by the split die side, resulting in a decrease in fluidity at the parison outlet.

The present invention aims to solve the above problems, and aims to prevent parison punctures and a decrease in fluidity at the outlet.

[Means for solving problems]

In the present invention, an extrusion die 1 is placed in the crack 12 of the split mold 11.
In a blow molding apparatus that introduces the parison 20 extruded from the extrusion die 6 and blows air into the parison 20 to mold the parison 20, a fitting hole 13 is formed at the entrance of the cavity 12 of the split mold 11, and the extrusion die 16 is provided with a tip head 17 that fits into the fitting hole 13 of the split mold 11, an annular parison discharge hole 18 is provided in the tip head 17, and an air blow hole 19 is provided in the center of the parison discharge hole 18. It is open and a heat insulating material 14 is provided on at least one of the inner peripheral surface of the fitting hole 13 of the split mold 11 or the outer peripheral surface of the tip head 17 of the extrusion die 16.

[Effect]

The present invention provides a (
) The tip head 17 of an extrusion die 16 is fitted into the fitting hole 13 via the heat insulating material 14, and air is blown into the parison 20 to form the parison.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Reference numeral 11 denotes a split mold, and a cavity 12 is formed in the joint surface of the split mold 11, and a fitting hole 13 is formed in the split mold 11 at the upper entrance of the cavity 12. This fitting hole 13 is provided with a semicircular recess in each split mold 11, so that the fitting hole 13 assumes a circular shape when the mold is closed.

Further, a heat insulating material 14 is embedded in the split mold 11 so as to surround the fitting hole 13. Further, a large number of narrow slits 1 are formed on the inner circumferential surface of the fitting hole 13 and the outer circumferential surface of the heat insulating material 14 as ventilation portions that communicate the outside with the carrier and the biddy 12.
5 is formed to allow ventilation between the inside of the cavity 12 and the outside.

Reference numeral 16 denotes an extrusion die disposed above the split mold 11 so as to be movable up and down.
A distal end head 11 that fits into a fitting hole 13 is provided, and an annular parison discharge hole 18 is provided on the lower surface of this distal head 17, and an air blow hole 19 is provided in the center of this parison discharge hole 18.
is opened.

Then, when the extrusion die 1G is lowered to a predetermined position, the parison 20 is discharged from the parison discharge hole 18 to face the cavity 12, and the split die 11 is closed, the fitting by each recess of the split die 11 is completed. The inner circumferential surface of the hole 13 presses and holds the outer circumferential surface of the tip head 17 of the extrusion die 16 from both sides via the heat insulating material 14 for air sealing, and the lower end of the parison 20 is pinched by the split die 11. Eat it up.

In this state, air is blown into the parison 20 from the air blowing hole 19 to form it.

By doing this, the parison 20 can be attached to the split mold 11.
No bulging outside, parison 20 punctures occur.
Also, since the heat insulating material 14 is interposed between the tip head 17 of the extrusion die 16 and the split die 11, the heat insulating material 14
As a result, the temperature drop in the extrusion die 16 is significantly reduced, and a drop in fluidity at the exit portion of the parison 20 is suppressed.

In addition, the inner peripheral surface of the fitting hole 13 of the split mold 11 and the heat insulating material 1
The slit 15 on the outer peripheral surface of the parison 20
When air is blown into the cavity, the air remaining between the parison 20 and the inner surface of the cavity 12 is discharged to the outside. The slits 15 are formed narrowly and provide only slight ventilation while maintaining sealing properties, so the parison 20 does not bulge out and bank through the slits 1 to 15.

In the above embodiment, the heat insulating material 14 is installed on the inner circumferential surface of the fitting hole 13 of the split mold 11, but as shown in FIG. A material 14 may be provided. Further, the heat insulating material 14 may be provided on both the inner circumferential surface of the fitting hole 13 of the split die 11 and the outer circumferential surface of the tip head 17 of the extrusion die 16. These heat insulating materials 14 include, for example, synthetic resins such as Teflon, epoxy, and nylon;
Or asbestos etc. are used.

In addition, in practice, the split mold 11 may be divided into two parts, or may be divided into three or more parts.

In addition, the ventilation section between the kitobitei 12 and the outside is provided by the slit 1.
5, it may be formed with a small hole, etc. Furthermore, the ventilation portion may be formed by the fitting hole 13 and the tip head 17 of the extrusion die 16.
It may be provided near any fitting part.

〔Effect of the invention〕

According to the present invention: 1. The proportion of the tip head of the extrusion die is W! [It fits into the fitting hole of the parison through the insulation material], so when air is blown into the parison, the parison will not bulge out of the mold and become punctured, and the parison discharge part of the extrusion die will Suppresses temperature drop and maintains good fluidity of parison?
l- can be done.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the device of the present invention, FIG. 2 is a cross-sectional view of the device in a closed state, and FIG. 3 is a cross-sectional view of another embodiment of the device of the present invention in a closed state. , 4 and 5 are cross-sectional views of conventional devices. 11. Split mold, 12. Sharpness, 13. Fitting
. Hole, 14...insulating material, 15...slit as ventilation section, 16...extrusion die, 17...tip head, 18...parison discharge hole, 19...air blowing hole, 20...parison.

Claims (2)

[Claims] (1) In a blow molding device that introduces a parison extruded from an extrusion die into the cavity of a split mold and blows air into the parison to form the parison, a fitting hole is formed at the entrance of the cavity of the split mold. The extrusion die is provided with a tip head that fits into the fitting hole of the split mold, an annular parison discharge hole is formed in the tip head, and an air blow hole is opened in the center of the parison discharge hole. A blow molding apparatus, characterized in that a heat insulating material is provided on at least one of the inner circumferential surface of the fitting hole of the split mold or the outer circumferential surface of the tip head of the extrusion die. (2) The blow molding apparatus according to claim 1, wherein the fitting part between the fitting hole of the split mold and the tip head of the extrusion die has a ventilation part between the cavity and the outside. .