Plastic and nonmetallic article shaping or treating: processes – Direct application of fluid pressure differential to... – Production of continuous or running length
Reexamination Certificate
2001-07-02
2004-02-24
Colaianni, Michael (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Direct application of fluid pressure differential to...
Production of continuous or running length
C264S515000, C264S154000, C264S163000, C264S173160
Reexamination Certificate
active
06696011
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a production of plastic products through a molding process and, more particularly, to a plastic product having desired thermal insulation property, desired light transmitting effect, desired buoyancy, and desired durability, and to a method and device for producing such plastic products by extruding a melted plastic material to form a plastic structural body, and sequentially blowing, filling and molding the structural body before the hardening of the body to produce resulting plastic products.
BACKGROUND OF THE INVENTION
In a conventional extrusion molding process, plastic material is melted at a predetermined temperature to become a half-melted gel. The half-melted plastic material is, thereafter, fed to an extrusion head by means of a feeding unit, such as a feed screw, and so a plastic structural body having an outer shape determined by the shape of a dice mold provided in the extrusion head is produced.
A conventional extrusion-molding device for performing such an extrusion molding process comprises a plurality of cores provided in the housing of an extrusion head. A dice mold, having a shape corresponding to a desired shape of resulting products, is set in the terminal of the housing. A water-cooling unit is provided outside the extrusion head for cooling the structural body discharged from the dice mold.
In a conventional extrusion molding process using such a conventional extrusion-molding machine, the shape of the resulting products is determined by the dice mold when the melted plastic material passes through the dice mold. In such a case, a plastic structural body is discharged from the dice mold while being initially cooled by a primary cooling unit provided around the dice mold, and is then cooled by a water-cooling unit longitudinally installed along a feeding passage extending from the dice mold. The structural body is, thereafter, cut by a cutter installed at the terminal of the passage.
The above-mentioned conventional extrusion molding process has been preferably used to form a variety of plastic products having the same cross-section, such as wires, rods and panels. As the plastic products produced by the conventional extrusion molding process are hollow members, they are preferably lightweight. However, the plastic products may be undesirably weak in their structure for an impact, particularly when they have thin walls.
In addition, the extrusion-molded plastic products are produced by cutting a linear structural body, and so each product has cut surfaces at both end surfaces of the product, with a cavity longitudinally formed in inner-space of each product. The longitudinal cavity has to been opened at both end portions.
A conventional extrusion molding process of producing such plastic products comprises the steps of: melting a plastic material; extruding the melted plastic material to feed the plastic material into a molding cavity defined by the housing and cores of an extrusion head; shaping a plastic structural body by extruding the plastic material through a dice mold installed at the terminal of the extrusion head housing; initially cooling the plastic structural body by a primary cooling unit provided around the dice mold; then cooling the structural body by a water cooling unit longitudinally installed along a feeding passage extending from the dice mold; and cutting the plastic structural body by a cutter installed at the terminal of the passage. Therefore, it is impossible to produce plastic products having shapes different from that of the dice mold through a conventional extrusion molding process.
A variety of plastic products, each having a completely sealed and completely continuous sidewall, a sealed cavity defined within the sidewall, and a shaping part having a desired shape and formed in the cavity, are preferably usable for a variety of applications in a variety of industrial fields. However, it is impossible to produce such plastic products through a conventional extrusion molding process or a conventional injection molding process.
In a conventional injection molding process, melted plastic material heated to a predetermined temperature is injected into a cavity defined between the open able top and bottom molds of an injection-molding machine. After the product is hardened, the top mold is separated from the bottom mold prior to ejecting the product from the cavity using an ejection unit. Therefore, the plastic products produced through a conventional injection molding process do not have a sealed cavity, but are open in their structures in the direction of mold opening.
In addition, even though plastic products are produced through a conventional injection molding process with a variety of cores, it is impossible to form a desired shaping part, such as a rib, in the cavity of the products.
It is also impossible to produce the above-mentioned plastic products, each having a completely sealed and completely continuous sidewall, a sealed cavity defined within the sidewall, and a shaping part having a desired shape and formed in the cavity, through another conventional forming process, such as a blow molding process or a vacuum forming process which is used for producing tubes, containers or a variety of casings in the prior art.
SUMMARY OF THE INVENTION
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a plastic product, which each have a completely sealed and completely continuous sidewall, at least one sealed cavity having a single or multi-layered structure and defined within the sidewall, and a shaping part having a desired shape and formed in the cavity.
Another object of the present invention is to provide a plastic product, which has an air suction valve and an air exhaust valve on its sidewall to perform a respiration action through the valves in response to thermal expansion or contraction of a sealed cavity inside the sidewall, thus being protected from undesired deformation or breakage regardless of a change in atmospheric temperature.
A further object of the present invention is to provide a plastic product, which has an integrated structure having filler, such as urethane filler, welded to a sealed cavity of a plastic structural body of the product.
Still another object of the present invention is to provide an extrusion molding method and device, which produces a plastic product through a continuous blow molding process and/or a mold forming process, the product consisting of a plastic structural body having a completely sealed sidewall, with a plurality of ribs formed on the sidewall to form a plurality of cavities in the structural body;
Another object of the present invention is to provide an extrusion molding method and device, which produces a plastic product through a filling process, in addition to a continuous blow molding process and/or a mold forming process, the product consisting of a plastic structural body having a completely sealed sidewall, with a plurality of ribs formed on the sidewall to form a plurality of cavities in the structural body, and a filler integrally filling each of the cavities;
Another object of the present invention is to provide an extrusion molding method and device, which produces a plastic product by continuously injecting a filler, such as resin foam, into the cavity of a plastic structural body of the product while forming the product, thus integrating the filler with the sidewall of the product.
Another object of the present invention is to provide plastic products including panel type, pipe type, channel type, door panel type, boat type, and column type having a specifically designed structure with a completely sealed and completely continuous sidewall and at least one sealed cavity defined inside the sidewall, thus having desired thermal insulation property, desired no flammability, desired light transmitting effect, desired buoyancy, desired durability; being preferably usable as interior or exterior materia
Lee Jae Wook
Yun Sun Young
Bachman & LaPointe P.C.
Colaianni Michael
Fontaine Monica A
Yun Sun Young
LandOfFree
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