Plastic article or earthenware shaping or treating: apparatus – Female mold and charger to supply fluent stock under... – With coupling between charger and mold
Reexamination Certificate
1999-10-18
2001-08-28
Nguyen, Nam (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Female mold and charger to supply fluent stock under...
With coupling between charger and mold
C425S409000, C425S450100, C425S451900, C425S589000, C425S595000
Reexamination Certificate
active
06280178
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to manufacture of millwork made of plastic, such as polyurethane, and, more particularly, is concerned with a molding apparatus having upper and lower composite mold/press units with replaceable mold cavity forming components for producing millwork products having different shaped profiles.
2. Description of the Prior Art
Due to the high cost of custom manufacture of wood and the persistent maintenance problems of wood in terms of rotting, cracking, warping, splintering and insect infestation, millwork for entry systems, window treatments, louvers, molding and architectural enhancements made of plastic, such as polyurethane, is increasingly being utilized in both commercial and residential construction, as well as, in historical restoration. Millwork made of plastic, sometimes referred to as formed millwork, is easy to handle, saws cleanly for miter cuts, and can be applied with construction adhesives and/or nails and screws. Such millwork does not need sanding or sealing and can be patched with ordinary (non-solvent) wood fillers. Furthermore, such millwork is substantially maintenance free in that its white acrylic prime finish will not peel and it is UV-stabilized to resist sun fading and readily accepts latex paint. Such millwork has the feel, density, and workability of wood while avoiding the aforementioned problems associated with wood. For convenience in terminology used hereinafter, the term millwork, formed millwork, molded millwork, or plastic millwork refers to millwork made of a plastic material, such as polyurethane, and are used interchangeably throughout this specification.
Heretofore, the process for manufacturing millwork has been simple and straight-forward piece work although very labor intensive and time-consuming. For any given end-product, the present manufacturing process involves, first, making a wood pattern of the desired product and, next, making a silicon rubber mold from the wood pattern which is the negative shape of the product. Then, the rubber mold is placed in a frame-box carrier which supports the mold such that the mold is confined to the shape of the pattern since otherwise the rubber could stretch and flex when it is filled. Following thereafter, the mold is sprayed with a releasing agent which will allow the molded product to be released from the mold and which will also provide a very smooth finish on one side of the product. The releasing agent actually is capable of forming a smooth finish skin on the product. Next, a suitable liquid plastic, such as polyurethane, is poured into the mold and a lid is placed over the open face of the mold. The liquid plastic can expand several times in volume due to an exothermic reaction that will occur in the polyurethane. The closed mold is then placed in a press for about thirty minutes (exothermic reaction time) such that the expandable polyurethane due to its confinement in the closed mold will increase in density as well as volume to provide the desired end-product. After the time has expired, the closed mold is removed from the press, its lid is removed and the product is removed from the mold. The product is now finished off by cleaning its edges, patching any pin holes therein and spray painting its top surface. The life of a normal rubber mold is approximately two hundred pours depending upon the complexity of the specific part, then the construction of a new rubber mold is required from the original pattern. Additionally, any given rubber mold is also limited to a small quantity of parts produced per day because of the heat build up in the rubber mold due to exothermic reaction of the injected material. It can be readily appreciated from the above description that the present manufacturing process is only capable of increasing production accompanied by greater labor utilization at increasing cost.
As the use of certain ones, such as interior and exterior molding, of the millwork pieces continue to increase, there is a need for introduction of innovations in the millwork manufacturing process which will lead toward the goal of achieving increased production of pieces at lower unit costs to be able to satisfy a growing market demand at a reasonable profit.
SUMMARY OF THE INVENTION
The present invention provides a molding apparatus designed to satisfy the aforementioned needs for innovations in the millwork manufacturing process. The present invention is the first to introduce injection molding techniques into the production of millwork products to enable increased production without increasing labor utilization and thus at lower unit cost. The molding apparatus of the present invention provides upper and lower composite mold/press units in which pressing and molding functions are substantially integrated together, unlike in the case of prior art injection molding machines, by an arrangement of operative components that occupy a relatively compact amount of space and effectively press and maintain a mold cavity of the apparatus in a closed condition as a millwork product is produced therein. Further, at least the lower composite unit of the apparatus utilizes easily replaceable mold cavity defining components for producing millwork products having different shaped profiles.
Accordingly, the present invention is directed to an injection molding apparatus for producing millwork pieces. The injection molding apparatus comprises: (a) a workstation supported on a support surface; (b) an elongated lower composite mold/press unit mounted upon the workstation and defining a lower portion of a mold cavity; (c) an elongated upper composite mold/press unit defining an upper portion of the mold cavity; (d) a plurality of support members spaced apart from one another along the lower composite unit, movably mounted to the workstation, and extending above the lower composite unit where the support members mount the upper composite unit generally above and for movement toward and away from the lower composite unit; (e) a plurality of actuators spaced apart from one another along the lower composite unit, mounted to the workstation, and coupled to respective ones of the support members such that actuation of the actuators to a first position causes movement of the support members in a first direction and places the upper composite unit in a mated relationship with the lower composite unit and thereby the upper and lower portions of the mold cavity in a closed condition whereas actuation of the actuators to a second position causes movement of the support members in a second direction and places the upper composite unit in an unmated relationship with the lower composite unit and thereby the upper and lower portions of the mold cavity in an opened condition; and (f) releasable locking means mounted on the workstation adjacent to the lower composite mold/press unit for releasably locking and maintaining the upper and lower composite units in the mated relationship and thereby the upper and lower portions of the mold cavity in the closed condition as a millwork product is produced in the mold cavity. The apparatus further comprises an ejector mechanism mounted on the upper composite unit for separating the product produced in the mold cavity from the upper composite unit when the mold cavity is in the opened condition.
More particularly, the lower composite unit includes a lower mounting plate mounted on the workstation, a lower mold part mounted on the lower mounting plate and defining the lower portion of the mold cavity, a plurality of fasteners removably attaching the lower mold part on the lower mounting plate, and a plurality of coolant flow paths defined through the lower mounting plate and extending between opposite ends thereof. The upper composite unit includes an upper mounting plate mounted to the support members, an upper mold part defining the upper portion of the mold cavity, a pair of opposite spacers disposed and extending between the upper mounting plate and upper mold part so as to space the upper mol
Del Sole Joseph S.
Flaunagan John R.
Nguyen Nam
SAR Development, LP
Swartz Michael R.
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