JPH05185428A - Method and apparatus for controlling thickness of parison - Google Patents

Abstract

PURPOSE:To control the thickness of a parison in the peripheral direction thereof over a wide range by moving a die and an annular disc. CONSTITUTION:In a method and apparatus for controlling the thickness of a parison, a die 2 and the annular disc 4 provided to the die 2 are moved in the diameter direction A of a cylindrical head main body 10, the wall thickness of the parison 20 in the peripheral direction thereof is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for controlling the thickness of a parison, and more particularly to a new improvement for controlling the thickness of the parison in the circumferential direction over a wide range.

[0002]

2. Description of the Related Art There are various conventional parison thickness control devices of this type, and a typical one of them is shown in FIG.
The structure disclosed in Japanese Patent Publication No. 28766 can be mentioned. That is, a slice lip 4 is provided only in the circumferential direction of the die 2 through which the core 1 penetrates so as to be able to move in and out in the radial direction of the die 2 by a hydraulic cylinder 3, and corresponds to the peripheral wall 4a of the slice lip 4. The interval 5a between the slits 5 in the portion to be covered was partially controlled, and the thickness of the extruded parison (not shown) in only a partial angular range in the circumferential direction was controlled.

[0003]

Since the conventional parison thickness control device is constructed as described above, the following problems exist. That is, as shown in FIG. 6, since it is possible to control only the wall thickness of a part of the parison in the circumferential direction, for example, in the case of a resin fuel tank used in a recent automobile, it is close to the ground. In terms of fire resistance, the surface should be thick, and on the opposite side, the top surface of the tank should be thin, and it is sufficient if the thickness is about half that of the fire resistant surface. Since there is only a very limited partial control of the wall thickness in the direction, there is much waste of the wall thickness where the wall thickness cannot be controlled, which is a serious issue for resin fuel tanks for automobiles, which are designed to be lightweight. Was there.

[0004]

According to the method for controlling the thickness of a parison according to the present invention, molten resin fed into a cylindrical head body having a core is passed through a ring-shaped slit formed between the core and the die. In the method for controlling the thickness of the parison by controlling the thickness of the parison, the circumferential thickness of the parison is measured by moving the die and the annular disc provided on the die in the radial direction of the cylindrical head body. It is a control method.

Further, in the parison thickness control device according to the present invention, the molten resin sent into the cylindrical head main body having the core built therein is passed through the ring-shaped slit formed between the core and the die to make the parison meat. In a parison thickness control device for controlling the thickness, a die provided at the lower end of the tubular head body and movable along the radial direction of the tubular head body, and a die provided at the bottom of the die along the radial direction. And a movable circular disk.

[0006]

In the method and apparatus for controlling the thickness of the parison according to the present invention, the die provided at the lower end of the cylindrical head body moves in the radial direction, and the ring-shaped disc provided at the bottom of the die moves in the radial direction. Since it moves, the radial interval of the annular slit itself can be freely controlled over a wide range in the circumferential direction.Therefore, the molten resin supplied to the annular slit has the annular slit whose interval is controlled over a wide range in the circumferential direction. By passing through, it is possible to obtain a parison whose thickness is controlled in a wide range in the circumferential direction.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a parison thickness control method and apparatus according to the present invention will be described in detail below with reference to the drawings. It should be noted that the same or equivalent portions as those of the conventional example will be described using the same reference numerals. 1 to 5 show a parison thickness control device according to the present invention. FIG. 1 is a sectional view of the entire structure, FIG. 2 is a sectional view taken along line XX of FIG. 1, and FIG. 3 is a sectional view taken along line Y- of FIG. The Y sectional view, FIGS. 4 and 5 are sectional views of the parison.

A reference numeral 1 in FIGS. 1 to 3 is a core built in the cylindrical head body 10.
A ring-shaped slit 5 for guiding a molten resin (not shown) is formed between the inner wall 10a of the cylindrical head body 10 and the outer peripheral surface 1a of the core 1.

At the lower end 10b of the tubular head body 10, a ring-shaped die 2 is provided via a ring-shaped holder 11 so as to be movable in the radial direction A of the tubular head body 10.
The ring-shaped slit 5 forms a discharge port 5a through the die 2. At the lower end of the core 1, an auxiliary core 1 screwed into a screw portion 12a of a shaft 12 provided in the core 1.
A is provided, and the distance between the discharge ports 5a can be adjusted by axially moving the auxiliary core 1A.

The die 2 is provided on the ring-shaped holding body 11 and is, for example, a rod 3a of a first cylinder 3 of hydraulic type.
Is configured to be able to move in the radial direction A described above.

A ring-shaped disc 4 is disposed in a ring-shaped holding groove 2b formed in the lower inner wall 2a of the die 2 so as to face the slit 5, and a second cylinder 3A provided in the die 2 is provided. The rod-shaped disc 4 is configured to be movable in the radial direction A by the rod 3Aa.

Next, in the above-mentioned structure, when the parison 20 is molded by the molten resin fed into the cylindrical head main body 10 from the extruder (not shown), first, the die 2 and the first cylinder 3 in FIG. When the parison 20 to be molded is brought to the right in the radial direction A by the, the portion shown by the arrow B has a sectional shape in which the thickness is controlled in a wide range along the circumferential direction, as shown in FIG.

Further, when the ring-shaped disc 4 is further moved to the left in the radial direction A in FIG. 1 in the state of the die 2, the thickness of the slit 5 in the circumferential direction extends over a wide range as indicated by an arrow C. It is possible to obtain the parison 20 that is thin and only the central portion is thick, and both sides are thin.

Therefore, unlike the conventional method, the parison 20
It is possible to control the wall thickness in a wide angle range in the circumferential direction, and it is also possible to make it thicker on the entire lower surface and thinner on the other parts, such as a resin fuel tank for automobiles. Can be formed.

The shapes of the die 2 and the ring-shaped disc 4 described above are merely examples. For example, by forming a groove or a protrusion on the inner wall surface of the die 2, the outer surface shape different from that described above can be obtained. You can also get your own parison.

[0016]

Since the method and apparatus for controlling the thickness of the parison according to the present invention are configured as described above, the following effects can be obtained. That is, since the die itself is movable in the radial direction and the ring-shaped disc provided in the die is also movable in the radial direction, the circumferential thickness can be reduced by combining the movement of the die and the ring-shaped disc. It is possible to obtain a freely controlled parison over a wide range. Also, the control range of the wall thickness is not limited to a limited part of the conventional narrow range, but can be controlled over a wide range in the circumferential direction.

[Brief description of drawings]

FIG. 1 is a sectional view showing a parison thickness control device according to the present invention.

FIG. 2 is a sectional view taken along line XX of FIG.

FIG. 3 is a sectional view taken along line YY of FIG.

FIG. 4 is a cross-sectional view showing a molded parison.

FIG. 5 is a cross-sectional view showing a molded parison.

FIG. 6 is a plan configuration diagram showing a conventional parison thickness control device.

[Explanation of symbols]

 1 core 2 die 4 ring-shaped disc 5 ring-shaped slit 10 cylindrical head body 10b lower end 20 parison A radial direction

Claims (2)

[Claims] 1. A molten resin sent into a cylindrical head body (10) containing a core (1) passes through an annular slit (5) formed between the core (1) and a die (2). In the parison thickness control method for controlling the thickness of the parison (20), the die (2) and the ring-shaped disc (4) provided on the die (2) are attached to the cylindrical head body (10).
By moving in the radial direction (A) of the parison (2
0) A method for controlling the thickness of a parison characterized by controlling the thickness in the circumferential direction. 2. A molten resin sent into a cylindrical head body (10) containing a core (1) passes through a ring-shaped slit (5) formed between the core (1) and the die (2). In the parison thickness control device for controlling the wall thickness of the parison (20), the lower end (1) of the cylindrical head body (10) is
0b) and is movable along the radial direction (A) of the cylindrical head body (10), and is provided below the die (2) along the radial direction (A). A parison thickness control device comprising a movable circular disc (4).