Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – Shaping against forming surface
Reexamination Certificate
1999-05-28
2001-06-19
Pyon, Harold (Department: 1722)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
Shaping against forming surface
C425S451700, C425S589000, C425S595000
Reexamination Certificate
active
06248281
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a compression apparatus for molding which applies compression force to a resin within a die during injection compression molding or press molding. The present invention also relates to an injection compression molding machine and an injection compression molding method which use the compression apparatus for molding.
2. Discussion of the Background
In injection compression molding, molten resin is charged into the interior of a closed die, which is then subjected to die clamping in order to apply compression force onto the molten resin, to thereby complete molding.
In such injection compression molding, since low pressure is employed for injection of resin, no warpage or distortion is imparted to a molded article. Therefore, a molded article having excellent shape is advantageously manufactured even if the molded article has a small wall thickness.
Generally, a molding machine for injection compression molding includes a die composed of a movable mold and a stationary mold, a mold clamping apparatus, and a compression apparatus. The movable mold is movably provided in the molding machine. The stationary mold is fixed to the molding machine. The mold clamping apparatus advances the movable mold toward the stationary mold. The compression apparatus is adapted to compress molten resin which has been charged into the die.
Japanese Patent Application Laid-Open (kokai) Nos. 57-95429 and 60-122128 discloses conventional compression apparatuses. In these apparatuses, a movable portion for adjusting the volume of a die is provided in the interior of the die; and the movable portion is advanced via a pin which abuts the movable portion in order to reduce the volume of the die, to thereby compress molten resin charged into the die.
Such apparatuses disadvantageously have limited utility, since they do not enable injection compression molding by use of an ordinary die containing no movable portion.
To solve the above-mentioned problem, the present inventor has proposed a compression apparatus (Japanese Patent Application Laid-Open (kokai) No. 7-164500). As shown in
FIG. 16
, the proposed compression apparatus
95
is a unit comprising a mechanism for pushing a movable mold
91
toward a stationary mold
92
, and is removably disposed between a die
93
, composed of the movable mold
91
and the stationary mold
92
, and a mold clamping apparatus
94
. A clearance a shown in
FIG. 16
has the same purpose as that of a clearance a shown in
FIG. 1
as described below.
As shown in
FIG. 17
, the compression apparatus
95
has slant members
97
and
98
arranged along the compression direction. Each of the slant members
97
and
98
has a slant surface
96
slanted with respect to the compression direction. Of these slant members, the slant members
98
located at the side of the mold clamping apparatus
94
are moved perpendicular to the compression direction, to thereby generate compression force.
A plurality of pairs each comprising one slant member
97
and one slant member
98
are provided. As shown in
FIG. 18
, the slant members
98
which are made movable are arranged so as to form a square. A rack
99
for synchronization is provided on a side face of each of the slant members
98
. A gear
100
for engaging the racks
99
is provided in the space surrounded by the slant members
98
. The racks
99
and the gear
100
constitute a synchronization mechanism
101
.
In the above-described compression apparatus
95
, there is employed a mechanism which generates compression force by pushing the entirety of the movable mold
91
. Therefore, the compression apparatus enables injection compression molding by use of an ordinary die containing no movable portion, so that utility is enhanced.
Also, since the motions of the slant members
98
are synchronized by means of the synchronization mechanism
101
, no bias is produced in pushing force generated by the slant members
98
, so that uniform compression force can be applied to the molten resin. As a result, a molded article having excellent dimensional precision and appearance is reliably molded.
However, the above-described compression apparatus
95
has an intricate structure in which the slant members
98
are arranged around the gear
100
of the synchronization mechanism
101
, and each of the slant members
98
is engaged with the gear
100
. Further, since a large drive force is applied to the slant members
98
, a large torque is applied to the gear
100
of the synchronization mechanism
101
. Therefore, the gear
100
must have a relatively large diameter, resulting in difficulty in reducing the size and weight of the compression apparatus.
Especially, in the case of molding of a large article, the compression apparatus may become considerably large and heavy, depending on the shape of the molded article. In this case, the compression apparatus cannot be attached to a molding machine.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the present invention is to provide a compression apparatus for molding which applies uniform compression force to molten resin, and facilitates downsizing of the overall compression apparatus and attachment of the compression apparatus to a molding machine. Another object of the present invention is to provide an injection compression molding machine and an injection compression molding method which use the compression apparatus for molding.
The present invention provides a compression apparatus for molding (first aspect) for applying compression force to a resin within a die during injection compression molding or press molding; and an injection compression molding machine (second aspect) and an injection compression molding method (third aspect) making use of the compression apparatus for molding.
According to the first aspect of the present invention, there is provided a compression apparatus for molding by use of a molding machine which includes a die comprising a movable mold and a stationary mold. In the molding machine, molten resin is charged into the die, and the movable mold is advanced so as to apply compression force to the molten resin, to thereby mold the molten resin. The compression apparatus is arranged in the rear of the movable mold. The compression apparatus includes first and second slant portions each of which has a slant face slanted with respect the advancement direction of the movable mold and which are arranged along the advancement direction of the movable mold. The slant face of the first slant portion is in surface contact with the slant face of the second slant portion. The first slant portion and the second slant portion are moved relative to each other in a direction perpendicular to the advancement direction of the movable mold, to thereby generate pushing force which pushes the movable mold toward the stationary mold. A plurality of sets each including the first slant portion and the second slant portions which move relative to each other in the same direction are provided in a plane which extends perpendicular to the advancement direction of the movable mold. The first slant portions or the second slant portions are engaged with a single interlock plate which is disposed to be movable in the moving direction of the slant portions.
In the compression apparatus, the interlock plate is preferably a plate-shaped rigid body which has an elongated hole extending along the moving direction of the slant portion, and a drive mechanism for driving the slant portion is preferably deposed inside the elongated hole.
The first and second slant portions may be disposed as follows. In addition to slant portions which move relative to each other in the same direction, slant portions which move relative to each other in a different direction are provided; and the latter slant portions are engaged with each other via a synchronization mechanism. In this case, groups of first or second slant portions which are generally engaged with their respective interlock plates may be engaged
Abe Tomokazu
Matsui Tsuneo
Idemitsu Petrochemical Co. Ltd.
Luk Emmanuel
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Pyon Harold
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