Plastic article or earthenware shaping or treating: apparatus – Distinct means to feed – support or manipulate preform stock... – Extrusion shaping means
Reexamination Certificate
1999-07-02
2001-05-15
Mackey, James P. (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Distinct means to feed, support or manipulate preform stock...
Extrusion shaping means
C425S115000, C425S327000, C264S252000, C029S428000
Reexamination Certificate
active
06231327
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention is directed, in general, to composite extrusion machines and, more specifically, to a composite extrusion and patterning machine that can extrude a composite onto an irregularly curved edge and place a pattern on the composite in situ and a method of manufacturing the machine.
BACKGROUND OF THE INVENTION
A particularly desirable aspect of furniture and cabinetry has been high-relief, decorative trim. Decorative elements on furniture and cabinetry have been traditionally applied as preformed molding incorporating the desired shape. For example, in the case of display shelves, decorative molding is often used on the edge of a wood shelf to hide the end and side grain. Solid wood molding is typically formed by multiple passes of routing and shaping tools, depending upon the complexity of the decorative design. Some molding, however, is manufactured by extruding a composite (essentially wood fiber and adhesive) material through a cross-sectional shaping nozzle and allowing the material to harden on a flat surface. The resulting molding is usually fastened to cabinetry by wire nails, brads and/or glue. Typically, the molding is mitered at the corners where the straight edges meet. However, this method of applying preformed molding is not useful for shelves, or other similar wood shapes that have other than straight edges. This is because the straight molding does not readily conform to shapes other than straight edges.
For regularly shaped objects, e.g., circular platters or disks, it is relatively easy to form a pattern on an edge of the platter. That is, the molding and shaping can take place at a constant distance from the centerpoint. In these cases, the workpiece may rotate with the applicator at a fixed distance, or vice versa. For irregularly shaped workpieces this approach does not work well because of the difficulty of maintaining a constant distance from the applicator to the workpiece edge. Alternatively, for shelves having other than straight edges, it is possible to have a skilled craftsman carve the relief from an oversize workpiece to form the desired pattern. However, this method is cost-prohibitive in terms of time, material and labor. Alternatively, for regularly shaped objects such as a picture frame, a custom mold may be made that fits around the object, such as a basic wooden picture frame. The composition is then injected into the mold, filling the voids and forming the desired shape. This system, however, is expensive in that a specific mold must be made for each different size frame. Therefore, for many commercial products, especially decorative display shelves, it would be highly desirable to directly form decorative molding on the edges of irregularly shaped wood products.
Accordingly, what is needed in the art is a machine that will apply and form decorative material on the edge of an irregularly shaped wood workpiece by extrusion of a composite material.
BRIEF SUMMARY OF THE INVENTION
To address the above-discussed deficiencies of the prior art, the present invention provides a material extrusion and patterning machine for a workpiece having an irregularly curved edge and a method of manufacturing the same. In one embodiment, the machine includes: (1) a frame, (2) a fixture coupled to the frame for rotation relative thereto and having a clamp adapted to hold the workpiece, (3) an extrusion head, coupled to the frame for translation relative thereto and adapted to move relative to the axis of rotation to follow the edge and (4) a mold mount, coupled to the frame for translation relative thereto and adapted to move relative to the axis of rotation to follow the edge, the extrusion head and mold mount cooperating to deposit the material on the edge and allow a mount mold to place a pattern on the material as the workpiece rotates relative to the frame.
The present invention therefore introduces a machine that is equipped to deposit and pattern a plastic material (such as a composite wood product, or “compo”) on the irregularly curved edge of a workpiece, such as a piece of wood. “Irregularly curved” is defined as having a varying radius of curvature or varying distance from a single point. A workpiece having an irregularly curved edge therefore cannot be circular. The present invention provides a machine that adjusts for varying radii of curvature or distance from a point on the workpiece by allowing the extrusion head and mold mount to move with respect to the workpiece. Alternatively, the machine may be configured to apply and pattern the compo on a face of the workpiece.
In one embodiment of the present invention, the fixture holds the workpiece such that the edge is radially outward from an axis of rotation of the fixture. Thus, the edge on which the material is desired to be deposited and patterned is proximate an outer periphery of the fixture, allowing the extrusion head and mold mount to be located radially outward of the workpiece from the fixture's axis of rotation. Of course, the extrusion head and mold mount may be located radially inward from an edge defining a periphery of an aperture in the workpiece, allowing such edge to be coated and patterned.
In one embodiment of the present invention, the fixture has a second clamp for holding a second workpiece oriented such that a second edge of the second workpiece is located radially outward of the axis of rotation. Sometimes it is not necessary to coat and pattern the entire edge of a workpiece (for example, when some of the edge is hidden and of no decorative value when the workpiece is eventually installed, as with a shelf) The present invention introduces an embodiment wherein the fixture can hold two workpieces. Preferably, one workpiece can be coated and patterned while the other (having been coated and patterned) is being replaced with one to be coated and patterned. However, one who is skilled in the art will recognize that the fixture may readily be configured to hold multiple workpieces.
In one embodiment of the present invention, the machine further includes: (1) a cam coupled to the fixture and having a surface that corresponds to a shape of the edge and (2) a follower, coupled to the extrusion head, that contacts and follows the surface to guide the extrusion head. Alternatively, the extrusion head can follow the edge itself, although this may wear the edge. In yet another embodiment, data concerning the geometry of the edge are preprogrammed into the machine, allowing the extrusion head and mold mount to be moved without having to sense where the edge is. Still further, the edge can be sensed by other than mechanical means, such as by optical sensors, coupled to a programmer that can compensate for extreme irregularities in workpiece shape.
In one embodiment of the present invention, the machine further includes a mold, the pattern being contained in indentations in the mold. The mold edges may be forcibly applied to the workpiece so as to form a tear line to separate excess material from the workpiece. Alternatively, the pattern may be contained on a tape applied on top of the material by the mold.
In one embodiment of the present invention, the machine further includes a mold, the mold being circular and adapted to rotate to place the pattern on the material. Alternatively, the mold may be of any other shape. For example, the mold may have multiple forms on a single mold wheel that are indexed to apply desired shapes.
In one embodiment of the present invention, the machine further includes: (1) a variable rate material pump coupled to the extrusion head and (2) a constant rate motor coupled to the fixture to rotate the fixture at a constant rate. Those skilled in the art will realize that an extrusion head will traverse the irregularly curved edge of a workpiece at a rate that depends upon the distance of the edge from the axis of rotation. Since this distance varies, the rate of traversal varies, and the rate at which material is extruded from the extrusion head should vary to compensate. In an alternative embodiment, the
Mihlhauser Bobby Allen
Shanahan James William
Del Sole Joseph S
Mackey James P.
Mastercraft Industries, L.P.
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