Plastic article or earthenware shaping or treating: apparatus – With transportation device for relocating molding apparatus...
Reexamination Certificate
2000-08-03
2003-02-04
Mackey, James P. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
With transportation device for relocating molding apparatus...
C425S182000, C425S435000, C425SDIG002
Reexamination Certificate
active
06514061
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to methods and apparatus for casting or forming various structures, and more specifically to a fixture providing for both elevation and rotation of a mold. The present fixture is adapted particularly for handling relatively large molds, as used in the forming of boat hulls, decks, and other large components formed of glass fiber and/or similar materials.
2. Description of the Related Art
The invention of methods of forming fine strands of glass fiber and other fine synthetic fibrous materials, means of weaving such materials to form sheets of cloth, and various resins for impregnating such materials to form composite structures, has led to a myriad of different products which were previously formed of other materials. For example, traditionally boats have been constructed of wood, and later riveted and/or welded sheet metal for recreational boats and the like. The development of glass fiber structures made rigid by impregnating with resins and curing, has greatly simplified the construction of such structures and reduced the hours of labor previously required.
Nevertheless, the use of glass and/or other fibers for forming large structures requires a significant amount of specialized equipment, in the form of molds for the hull and other large components, resin mixing equipment, large clean areas for laying out and cutting the glass fiber cloth, etc. Probably the most cumbersome piece of equipment is the mold itself for the boat hull, which is the largest single component of such a craft. Such molds are quite heavy, due to the need for rigidity to form a precisely shaped and dimensioned hull. As a result, they are quite difficult to manipulate, with a number of workers and/or fork lifts, cranes, etc. being required to handle such molds.
Yet, frequent handling is a requirement with such molds, as they typically must be positioned or oriented for access by workers for the layups of glass fiber or other synthetic cloth and resin which are used to form the structure. Such molds are generally rotated or tilted to one side to provide for ease of access for layups along that side of the hull, and then rotated back to the opposite side to facilitate layups on that side. Also, it is critical that the mold be kept very clean, in order to provide the smoothness desired for the completed hull and to preclude contamination of the materials used for the structure. Accordingly, such molds are often stored in an inverted position when not in use. The raising and lowering of such molds is also frequently required, for ease of access to the interior by workers and to provide clearance for rotating the mold from one to another working position or for inversion for storage.
Heretofore, such rotating, lifting, and lowering of relatively large molds was often done by means of cranes and/or fork lifts, using heavy straps and a considerable amount of muscle power by several workers. While some devices have been developed to assist in the movement and orientation of such relatively large molds, none, to the knowledge of the present inventor, provides for complete powered rotation of a large mold as well as providing for powered lifting and lowering of the mold. The present invention responds to this need by providing the above functions, thereby greatly reducing the need for additional equipment in the form of cranes, hoists, lifts, etc., and also greatly reducing the manpower which might otherwise be required for the lifting and/or rotation of a large, heavy mold structure and thereby greatly increasing safety for such workers. A discussion of the related art of which the present inventor is aware, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 4,247,279 issued on Jan. 27, 1981 to William E. Masters, titled “Rotational Molding System,” describes an apparatus providing periodic heating of two separate molds during curing operations. The molds are on a track which passes through the curing oven, and are alternatingly installed in the oven from opposite ends. Masters also provides a remotely powered system for rocking the molds about their lateral axes, and for rotating the molds about their longitudinal axes. However, Masters does not provide any means of elevating his molds, as provided by the present fixture.
U.S. Pat. No. 4,354,819 issued on Oct. 19, 1982 to Jakob Wirz, titled “Multi-Pivotable Mold Carrier Clamping Apparatus,” describes a relatively small clamp table for holding a mold. The Wirz mold carrier has no wheels or casters, and is relatively immobile compared to the present fixture with its wheels which provide a degree of mobility. The two clamp faces are flat plates, precluding placement of a large mold structure having an irregular configuration, such as a large boat hull. While the Wirz device provides for lifting and rotation of the mold held therein, the rotation is about a vertical axis, rather than about a horizontal, longitudinal axis of the mold carried therein, as provided by the present fixture.
U.S. Pat. No. 4,360,334 issued on Nov. 23, 1982 to Gunther Kiefer, titled “Thermoforming Machine,” describes a machine having three separate compartments for containing a plastic sheet therein, heating the sheet to soften the plastic, and introducing pressure into the mold to form the plastic sheet according to the interior shape of the mold. This process is accomplished via three separate molds and stations, with each handling one of the steps in the process. The forming station provides for elevating the mold for clearance for a deep draw mold. However, Kiefer does not rotate a single mold generally through its longitudinal axis, nor does he provide for elevating the mold by means of a single hydraulic or other powered strut or cylinder, as provided by the present positioning fixture invention.
U.S. Pat. No. 4,632,654 issued on Dec. 30, 1986 to Jerome H. Lemelson, titled “Rotational Molding Apparatus,” describes an apparatus more closely resembling the rotational molding system of the '279 U.S. patent to Masters, discussed further above, than the present invention. Lemelson provides only a single mold carriage structure through the heating oven, rather than the two carriages of Masters. However, the same points of distinction between the Masters apparatus and the present invention, i. e., the lack of any elevating means, also apply to the apparatus of the Lemelson '654 U.S. patent in comparison to the present positioning fixture invention.
U.S. Pat. No. 4,767,299 issued on Aug. 30, 1988 to Peter Friesen, titled “Rotational Molding Machine,” describes an oven for heating thermoplastic materials during the molding process. The oven contains a rotary drive mechanism providing rotation about two mutually perpendicular axes, unlike the single longitudinal axis provided by the present positioning fixture. It is also noted that Friesen does not provide any means of elevating the mold, either within or without the oven, whereas the present fixture allows the mold to be elevated and lowered as desired to facilitate access thereto. Moreover, the Friesen mold is relatively fixed, whereas the present positioning fixture is relatively mobile, with its wheeled frame.
U.S. Pat. No. 5,028,230 issued on Jul. 2, 1991 to Gordon S. Hunter, titled “Machine For Handling Molds In Injection Molding,” describes an apparatus having two opposed mold attachment faces at opposite ends thereof. Both are arcuately translatable so the faces are horizontal, for cleaning and other work. One face is horizontally movable relative to the other, to adjust the spacing therebetween. However, the rotating axes of the Hunter machine are not horizontally disposed and concentric with one another, and thus cannot rotate a single, fixed object therebetween, as provided by the present positioning fixture. Moreover, Hunter does not provide any means of elevating or lowering a mold held within his machine, nor does he provide any means of mobility for the machine, which features a
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