JPH03150110A - Variable die for forming parison having different diameter - Google Patents

Abstract

PURPOSE:To manufacture perison, the outer diameter and wall thickness of which change axially, by a structure wherein a rotating blade driving device for rotating all rotating blades by the same angle in order to change the diameter of a variable diameter die part, a mandrel for changing the width of parison extruding space and a mandrel driving device for shifting the mandrel are provided. CONSTITUTION:A driving ring 2 rotates all engaging rotating blades 1 by the same angle through gears. Through the rotation of the rotating blades 1, the inner diameter of an extrusion port 9 is changed so as to be able to control the outer diameter of parison to be extruded to the desired dimension. A mandrel 10 has stepped parts 11, which have various diameters and locate nearly in the extrusion port 9 and is connected by its end opposite to the stepped part 11 to the tip of the rod 15 of a hydraulic cylinder 13 through a coupling 14. By the shifting of the rod 15 of the hydraulic cylinder 13, the mandrel 10 is shifted axially, resulting in changing the width of the space, which is produced between the stepped parts 11 having various diameters and the extrusion port 9 and through which parison is extruded. As a result, the wall thickness is changed in response to the axial position of the mandrel 10, resulting in allowing to control the wall thickness of the parison to the desired dimension.

Description

[Detailed description of the invention]

[Industrial Field of Application J] The present invention relates to the structure of a die for producing a parison used in blow molding of thermoplastic resin. [Prior Art 1] In the prior art, a parison of thermoplastic resin is extruded from a space between a gouer having a fixed inner diameter and a mandrel having a fixed outer diameter, so that the outer diameter of the extruded parison is The diameter and wall thickness were constant in the axial direction. Since the outer diameter and wall thickness of the parison are constant in the axial direction, when manufacturing products with varying outer diameters, the wall thickness of the product may not be uniform, which may cause strength problems, or the outer shape of the product may change. The desired product shape could not be obtained due to the limited degree of

[Problem to be solved by the invention]

An object of the present invention is to provide a variable die for forming parisons with different diameters for producing parisons whose outer diameter and wall thickness vary in the axial direction. Means for Solving Problems 1 According to the present invention, there are a plurality of rotary blades, the axes of the rotary blades are arranged at equal intervals on one circumference, and the rotary blades are rotatable on the axis. Each of the rotor blades has a rotor blade that contacts an adjacent rotor blade near its radially outer tip and forms a variable diameter die portion whose diameter changes; a rotary vane drive device that rotates all of the rotary vanes at the same angle in order to change the diameter; and a mandrel that has a plurality of step sections with different diameters, and the mandrel moves in the axial direction within the diameter of the variable diameter die section. a mandrel whose movement changes the width of the parison extrusion space between the variable diameter die portion and the step portion of the mandrel; and the mandrel to change the width of the parison extrusion space. A variable die for forming parisons of different diameters is provided having a moving mandrel drive device. The variable die for forming a parison of different diameters operates the rotary blade drive device and the mandrel drive device emphatically,
A variable die for forming parisons with different diameters may be used, which forms parisons having different outer shapes and different wall thicknesses. Alternatively, the rotary blade drive device is an annular body, and a gear is provided on the inner diameter of the annular body, and each of the rotary blades has an outer peripheral gear, and these gears are engaged to cause the rotary blade drive device to rotate. It may also be a variable die for forming parisons of different diameters, in which the rotary blades are driven by the following. 1 Embodiment - In the variable die for forming parisons of different diameters according to the present invention shown in FIGS. The rotational axes of are arranged at equal intervals on one circumference. A drive ring 2 is arranged outside the rotor 1 and surrounds the rotor 1. A gear is provided on the inner diameter portion of the drive ring 2, and engages with a gear provided on a part of the rotor blade 1 to drive the rotor blade 1 through the same angle. The drive ring 2 is rotatably supported by the carrier body 5 via four guide rollers 3 which are rotatably supported by the carrier body 5. Drive ring 2
A gear is provided on a part of the outer periphery of the rack 6 and engages with the rack 6. The rack 6 is slidably supported by the carrier body 5 in the tangential direction of the outer circumferential portion of the drive ring 2, and has a threaded portion inside and engages with the threaded portion of the shaft. The shaft is rotated a desired amount by a servo motor 8. As the shaft rotates, the rack 6, which is engaged through the threaded portion, slides in the tangential direction of the outer circumference of the drive ring 2, thereby rotating the drive ring 2, which is held through gears, by a desired amount. The drive ring 2 rotates all the rotor blades 1 engaged through gears by the same angle. As the rotor blade 1 rotates, the inner diameter of the extrusion port 9 formed near the tip of the rotor blade 1 changes. In this way, by changing the inner diameter of the extrusion port 9, the outer diameter of the extruded parison can be controlled to a desired dimension. The mandrel 10 is axially slidably supported within the body 12 and extends into the extrusion port 9. The mandrel 10 has a stepped portion 11 of varying diameters near where it is located within the extrusion opening 9. At the opposite end of the step section 11, the mandrel 10 is connected via a coupling 14 to the tip of a rod 15 of a hydraulic cylinder 13. The hydraulic cylinder 13 is connected to the rod 15 by a directional control valve (not shown).
movement is controlled. Rod 15 of hydraulic cylinder 13
The movement of the mandrel 10 causes the mandrel 10 to move in the axial direction, and the width of the space formed between the stepped portion 11 having various diameters and the extrusion opening 9 changes. Since the parison is extruded through this space, the wall thickness of the ballin changes depending on the position of the mandrel 10 in the axial direction. In this way, the thickness of the parison can be controlled to a desired dimension. Thermoplastic resin such as polyethylene heated to a temperature that allows it to maintain sufficient fluidity is introduced into the extrusion port 9 through the resin passage 17 by the screw 16. The thermoplastic resin is applied to the stepped portion 11 of the mandrel 10 and the extrusion port 9.
It is extruded through the space formed between the two and becomes a cylindrical parison. At this time, the rotor blade 1 is controlled by the servo motor 8.
The internal diameter of the extrusion port 9 is appropriately changed by controlling the rotational position of the extrusion port 9, and the axial position of the stepped portion 11 of the mandrel 10 is controlled by a hydraulic cylinder to separate the stepped portion 11 and the extrusion port 9.
By changing the width of the space formed between the two, it is possible to extrude a parison having desired external dimensions and wall thickness.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a parison manufacturing apparatus equipped with a variable die for forming parisons of different diameters according to the present invention, and FIG. 2 is a partial cross-sectional view of a variable die for forming parisons of different diameters according to the present invention. DESCRIPTION OF SYMBOLS 1... Rotating blade, 2... Drive ring, 3... Guide roller, 4... Bearing, 5... Body, 6...
Rack, 7...shaft, 8...servo motor,
9--Extrusion port, 10--Mandrel, 11--Step part, 12--Main body, 13--Hydraulic cylinder-, 14
...Coupling, 15...Rod, 16...Screw, 17...Resin passage.

Claims (3)

[Claims] (1) A plurality of rotor blades, the axes of the rotor blades are arranged at equal intervals on one circumference, the rotor blades are rotatable on the axis, and each of the rotor blades has a tip end thereof. A rotor blade that forms a variable diameter die portion whose diameter changes by contacting neighboring rotor blades in the vicinity, and a rotor drive device that rotates all the rotor blades at the same angle in order to change the diameter of the variable diameter die portion. and a mandrel having a plurality of step portions of different diameters, the mandrel being movable in the axial direction within the diameter of the variable diameter die portion, and the movement causing the variable diameter die portion and the step portion of the mandrel to move in the axial direction. A variable die for forming parisons of different diameters, comprising: a mandrel that changes the width of a parison extrusion space between the parison extrusion space; and a mandrel drive device that moves the mandrel to change the width of the parison extrusion space. (2) A variable die for forming parisons of different diameters according to claim 1, in which the rotary blade drive device and the mandrel drive device are operated in cooperation to form parisons having different external shapes and different wall thicknesses. A variable die for forming parisons with different diameters. (3) A variable die for forming parisons of different diameters according to claim 1, wherein the rotary blade drive device is an annular body, a gear is provided on the inner diameter part of the annular body, and each of the rotary blades is A variable die for forming parisons of different diameters, which has outer circumferential gears, and these gears engage to achieve driving of the rotary blades by the rotary blade drive device.