Plastic article or earthenware shaping or treating: apparatus – Stock pressurizing means operably associated with downstream... – Including auxiliary shaping means associated with molding...
Reexamination Certificate
2001-05-30
2004-02-03
Eashoo, Mark (Department: 1732)
Plastic article or earthenware shaping or treating: apparatus
Stock pressurizing means operably associated with downstream...
Including auxiliary shaping means associated with molding...
C425S382300
Reexamination Certificate
active
06685460
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention belongs to the technical field of extrusion molding and relates to an extrusion molding machine by which a molten resin material is extruded through a die by an extruder and further extruded through a pair of delivery rolls.
2. Description of the Related Art
As shown in
FIG. 11
, a molding part
610
in a conventional molding machine is provided with a pair of upper and lower delivery rolls
601
supported by a frame
605
, and a rolling part
607
between this pair of delivery rolls
601
is arranged before a die
602
installed at the end of an extruding machine
4
.
Upon extrusion of a molten resin material in a cylinder
42
by rotating a screw
41
in the extruder
4
, the molten resin material is passed through a resin flow path
621
in the die
602
and extruded from the discharge opening at the end of the die
602
, and by rotating a pair of the delivery rolls
601
, the molten resin material extruded toward the rolling part
607
between the delivery rolls
601
is delivered from the delivery part
608
at the opposite side of the rolling part
607
to form a product sheet S. The molten resin material is molded in this manner into the product sheet S by the extrusion molding machine equipped with a pair of the delivery rolls
601
.
As the molten resin material, various thermoplastic resins and rubber materials are used. A lubricant is added to this molten resin material to improve the releasability of the product sheet S from the delivery rolls
601
, a foaming agent is added in foaming molding, and various additives are incorporated depending on molding processability and characteristics of moldings.
Since the rolling part
607
between a pair of the delivery rolls
601
is open, the molten resin material extruded from the die
602
is exposed immediately to atmospheric pressure. Accordingly, there Is a problem that a part of the compounding ingredients in this molten resin is diffused into the atmosphere.
For example, when a molten resin material containing a foaming agent is used in foaming molding, there is a problem that upon extrusion of the molten resin material containing a foaming agent from the die
602
, the melting viscosity of the molten resin material is low so that the gas in the resin material cannot be maintained in the resin material, thus diffusing into the atmosphere, breaking bubbles and roughing the surface of the product to worsen the outward appearance.
Further, when highly volatile compounding ingredients are contained, a part of the volatile compounding ingredients is evaporated upon extrusion of the molten resin material from the die
602
. If such evaporated volatile compounding ingredients are, for example, a lubricant added for improving releasability from the delivery rolls
601
, the release of the product sheet S from the delivery rolls
601
is deteriorated to worsen the surface conditions of the delivered product sheet S.
SUMMARY OF THE INVENTION
The object of the present invention is to prevent diffusion etc. of compounding ingredients in a molten resin material upon extrusion of the molten resin material from a die in “a molding extrusion machine comprising a pair of delivery rolls arranged forward continuously with a die attached to the end of an extruder by which a molten resin material is extruded through the die toward a rolling part between the delivery rolls and further extruded through a pair of the delivery rolls”.
The technical means taken for solving the problem described above are as follows:
“Gas-sealing molds in intimate contact with both sides at least at the top of the die at the side of the discharge opening are provided to close openings in both sides of the rolling part so that supporting parts in both sides of a pair of the delivery rolls are formed into an air-tightness keeping part by said gas-sealing molds.”
The technical means described above act as follows.
The gas-sealing molds are provided in intimate contact with both sides at least at the top of the die at the side of the discharge opening thereby closing openings in both sides of the rolling part, so that the space in the rolling part between the delivery rolls is closed by the gas-sealing molds and the die. Further, the supporting parts for a pair of the delivery rolls are formed into an air-tightness keeping part by said gas-sealing molds, so that in both sides of the delivery rolls, the gas-sealing between the delivery roll and the gas-sealing mold is achieved by said gas-tightness keeping part.
Therefore, upon extrusion of the molten resin material out of the die, the rolling part is highly airtight to form a high-pressure zone kept at high pressure. Accordingly, the molten resin material extruded out of the die can be maintained at high pressure even in the rolling part.
Another technical means is “the die is intimately and externally fitted with gas-sealing molds being open forward, a pair of the delivery rolls is accommodated in the gas-sealing molds, and supporting parts in both sides of a pair of the delivery rolls are formed into an air-tightness keeping part by said gas-sealing molds.”
In this case, a pair of the delivery rolls is accommodated in the gas-sealing molds with which the die is intimately and externally fitted, and thus the space in the rolling part between the delivery rolls is closed by the gas-sealing molds and the die. In this case too, the supporting portions in both sides of a pair of the delivery rolls are formed into a gas-tightness keeping portion, so that in both sides of the delivery rolls, the gas-sealing between the delivery roll and the gas-sealing mold is achieved by said gas-tightness keeping part. By this constitution, the space in the rolling part is rendered highly airtight.
In this case too, therefore, the molten resin material is extruded from the die thereby reducing the leakage, out of the highly airtight rolling part, of the air and volatile components and a foaming agent etc. for foaming molding, to achieve a high-pressure zone kept at atmospheric pressure or more. By this constitution, the molten resin material extruded from the die is pressurized at atmospheric pressure or more, even in the rolling part. That is, the molten resin material is kept at atmospheric pressure or more until it is formed into a product sheet by delivery with a pair of the delivery rolls.
Said gas-tightness keeping part is constituted by “interposing an O-ring in a freely rotating part between the rotating shaft of each of the delivery rolls and the gas-sealing mold.”
In each of the technical means wherein “said gas-tightness keeping part comprises resin packing interposed inside of the O-ring”, the gas sealability between the delivery roll and the gas-sealing mold can be further improved. In addition, even if a part of the molten resin material extruded from the die permeates into the supporting parts at both sides of the delivery rolls, the molten resin material is sealed by the resin packing thereby preventing the leakage of the molten resin material from the gas-sealing molds.
In each of the technical means wherein “said die is thinning toward its top along the rolling faces of the delivery rolls, and the top is inserted into the rolling part with a gap therebetween to prevent the top from contacting with the rolling face”, the air-tightness of the space in the rolling part can be further improved by the thinning part of the die, and the maintenance of the high pressure in the rolling part as the high-pressure zone can be further improved.
In each of the technical means wherein “at least one member of the delivery roll, the die and the gas-sealing mold has a temperature-regulating function”, not only the viscosity of the extruded molten resin material but also the surface temperature of the extruded molten resin material can be regulated thereby preventing disruption of foams more effectively, to provide a product with a good appearance.
In each of the technical means wherein “a pair of the delivery rolls is delivery rolls rotated by a rotation dri
Kuroda Ryuma
Nodono Mitsunori
Eashoo Mark
Fitch Even Tabin & Flannery
Sumitomo Chemical Company Ltd.
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