16 Plastics 2017.2. 1. Introduction 3D-blow molding, which molds crooked products two or three dimensionally or products with bellows without any flash, is done by storing the parison into the blow mold cavity. In this article, we introduce Multi-dimensional Extrusion Molding which we developed (Hereinafter referred to as MES) as well as several examples combined the method with exchange blow molding which molds hard material and soft material as one product. These molded products are used for automotive air intake ducts etc. that require 2D and 3D shapes and bellow structures. The advantages of these methods are lighter weight, decreased part numbers, products with advanced features, and cost reduction. 2. The mechanism and characteristics of MES The MES’s mechanism of storing the parison to the blow mold cavity is done by moving the extruder and the blow mold relatively in the X-Y direction to rest the parison into the cavity of the lower half of the mold. After the parison is set in the lower mold, the mold is moved to the mold closing unit to close the mold with the upper half. Drawing 1 below shows the basic mechanism of MES with the moving extruder. Fig. 1 Basic mechanism of MES The mechanism consists of an extruder unit that moves in the X-Y direction while feeding the plasticized resin parison, and the horizontally placed lower mold and the mold closing unit which moves and closes the horizontally placed mold with the upper half. The controls for the mold movement, mold close, parison feed and the wall thickness is done by a control unit with NC equipment. The conventional blow molding method feeds the parison in a vertical direction and pinches that parison with a vertical mold. Therefore conventional blow molding has high possibility of drawdown (when a tube of melted resin is fed downward the gravity pulls the resin down causing the resin tube to be thin in the top part of the tube causing thin wall thickness) resulting in molding to be possible by only high viscosity material (e.g. PE Extruder Unit Mold Closing Unit Mold Closing Unit Movable Plate B Mold (Upper) B Mold (Lower) A Mold (Upper) A Mold (Lower) Slide table Parison
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16 Plastics 2017.2.
1. Introduction
3D-blow molding, which molds crooked
products two or three dimensionally or products
with bellows without any flash, is done by storing
the parison into the blow mold cavity. In this article,
we introduce Multi-dimensional Extrusion Molding
which we developed (Hereinafter referred to as
MES) as well as several examples combined the
method with exchange blow molding which molds
hard material and soft material as one product.
These molded products are used for automotive air
intake ducts etc. that require 2D and 3D shapes and
bellow structures. The advantages of these
methods are lighter weight, decreased part
numbers, products with advanced features, and
cost reduction.
2. The mechanism and characteristics of MES
The MES’s mechanism of storing the parison to
the blow mold cavity is done by moving the
extruder and the blow mold relatively in the X-Y
direction to rest the parison into the cavity of the
lower half of the mold. After the parison is set in
the lower mold, the mold is moved to the mold
closing unit to close the mold with the upper half.
Drawing 1 below shows the basic mechanism of
MES with the moving extruder.
Fig. 1 Basic mechanism of MES
The mechanism consists of an extruder unit that
moves in the X-Y direction while feeding the
plasticized resin parison, and the horizontally
placed lower mold and the mold closing unit which
moves and closes the horizontally placed mold
with the upper half. The controls for the mold
movement, mold close, parison feed and the wall
thickness is done by a control unit with NC
equipment.
The conventional blow molding method feeds
the parison in a vertical direction and pinches that
parison with a vertical mold. Therefore
conventional blow molding has high possibility of
drawdown (when a tube of melted resin is fed
downward the gravity pulls the resin down causing
the resin tube to be thin in the top part of the tube
causing thin wall thickness) resulting in molding to
be possible by only high viscosity material (e.g. PE
Extruder UnitMold Closing
Unit
Mold Closing
Unit
Movable
Plate
B Mold
(Upper)
B Mold
(Lower)
A Mold
(Upper)
A Mold
(Lower)
Slide table Parison
Fig. 1 The basic mechanism of MES
17 Plastics 2017.2.
and PP). Also, in ducts and hoses with complicated
shapes the conventional blow molding method
causes high rate of burrs and has bad first pass
yield.
MES on the other hand, has the extruder follow
the cavity in an X-Y direction over the horizontally
placed lower mold to store the parison in the cavity.
This allows the dye head (the point where the
parison is fed) and the lower mold cavity in close
distance. Therefore the drawdown of the parison is