Plastic and nonmetallic article shaping or treating: processes – Mechanical shaping or molding to form or reform shaped article – To produce composite – plural part or multilayered article
Reexamination Certificate
2000-05-31
2003-11-18
Kuhns, Allan R. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
Mechanical shaping or molding to form or reform shaped article
To produce composite, plural part or multilayered article
C249S176000, C264S299000, C264S319000
Reexamination Certificate
active
06649110
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
(Not Applicable)
STATEMENTS AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT
(Not Applicable)
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a mold apparatus and method for manufacturing panels. More particularly, this invention relates to a method for manufacturing panels having, as desired, one or more areas of reduced material comprising a facing sheet and cell forming walls extending in roughly perpendicular fashion from said facing sheet, wherein said cell forming walls are integrally formed with and attached to said facing sheet. More particularly still, the present invention relates to a method of molding panels from thermoplastic resins and other moldable materials which requires significantly less energy than other known molding methods. More particularly still, the present invention relates to a method of molding panels from thermoplastic resins and other moldable materials wherein said panels have one or more sections which exhibit characteristics of a solid panel, that is, portions of said panels which have roughly continuous outer surfaces.
2. Description of Related Art
Panels constructed of various materials, and embodying many different sizes and shapes, have been known in the art and used in a multitude of applications for some time. Although such applications are too numerous to name, some examples include the use of large-scale panels made of wood, gypsum, metal and/or fiberglass in connection with the construction of buildings and other structures. Additionally, panels of various sizes have routinely been used, individually and in combination with one another, as load-bearing elements.
In most applications, it is beneficial for panels to exhibit desirable strength characteristics, while remaining relatively light. In this regard, attempts have been made to utilize thermoplastic resins and other synthetic materials to replace materials like metal, wood and concrete to construct such panels. However, to date, it has been difficult to manufacture panels from thermoplastic resins and other moldable materials having the desired strength and weight characteristics in a cost effective manner. This is particularly true in the case of large-size panels.
While it may be beneficial to manufacture solid panels, it is generally known that use of cellular structure in panels can greatly reduce material requirements while maintaining, or in some cases actually increasing, strength characteristics of said panels. In most instances, such material reduction results in significant cost savings. In the case of panels molded from thermoplastic resins and other moldable synthetic materials, the use of cellular structure to reduce material requirements can have a dramatic effect on the ultimate cost of such molded panels.
Panels exhibiting cellular structure, in general, and hexagonal shapes or honeycombs, in particular, have been known in the art for some time. Similarly, molding apparatuses and methods of manufacturing panels containing cellular structure are also generally well known in the art.
U.S. Pat. No. 2,892,339 to Flower et al, discloses panels having open faced cellular structure which are constructed of gypsum plaster or other moldable composition, as well as a method of manufacturing same. The panels described in the '339 patent include at least one facing sheet having integral and homogenous cell forming walls disposed with their axes at a right-angle to said facing sheet. The '339 patent further describes a method of manufacturing such panels comprising a facing-mold table for containing a volume of plaster or other moldable material, a series of deformable plugs or offsets for molding cell walling in one with a facing layer of plaster or other moldable material, a vertically movable framing on which such plugs are mounted in spaced relation, means for immersing said plugs in plaster or other moldable material of the facing-mold to form the whole of the cell walling for a panel simultaneously with the facing, and means for contracting the plugs for their withdrawal from the plastic or other moldable material.
U.S. Pat. No. 3,509,005 to Hartig discloses a method of applying molten thermoplastic resin into a pattern disposed on the surface of a rotating roll to form a web of ribs integrally molded to a continuous film.
U.S. Pat. No. 3,617,416 to Kromrey describes a structure consisting of fiber-reinforced cells, such as honeycombs, which are integrally molded to a substrate material, as well as a method of manufacturing said structure. The method described in the '416 patent utilizes dies formed as continuous individual strips of cells having a desired end configuration. Said die strips are placed side by side and interfitted to form a mold for a honeycomb structure. Fibers or fabric pre-impregnated with curable resin are wound between the dies to form cellular walls of a honeycomb structure, as well as a substrate layer. The entire structure is then subjected to conditions of elevated temperature and pressure to effect a cure.
U.S. Pat. No. 5,776,582 to Needham discloses loadbearing structures having interlockable edges. The '582 patent addresses a method of molding panels having cellular structure out of thermoplastic resins and other materials. The '582 patent briefly describes a pan-like lower mold member into which thermoplastic material and reinforcing fiber is placed. Thereafter, an upper mold member having positive plug extensions are combined with the lower mold member, and heat and pressure is applied. The positive plug extension is used to deform the resin and reinforcing material to the desired configuration.
Similarly, U.S. Pat. No. 5,888,612 to Needham, et al, also describes a method of molding panels containing cellular structure. A lower mold member having an ordinary smooth interior surface is first filled with thermoplastic material. An upper mold member is configured with positive molding dies. Said upper and lower mold members are combined, and the dies of said upper mold member are used to displace said thermoplastic material. Thereafter, the apparatus is subjected to conventional heat and pressure to form the desired panel having cellular structure.
One significant problem encountered when molding panels having cellular structure under the prior art relates to uniform placement of thermoplastic resin or other moldable material which form cell walls. Under the prior art, thermoplastic resin or other moldable material is loaded into a lower mold member which is typically in the form of a pan. Thereafter, an upper mold member having positive standoffs, spaced apart in a desired pattern, is forced into said lower mold member. In order to create the desired cell-forming walls, the thermoplastic resin or other moldable material must be displaced by said upper mold member in order to fill voids between said positive standoffs. Unless such resin or other material is uniformly and adequately distributed between said positive standoffs, pits or voids will often develop in the cell-forming walls. Because such thermoplastic resin or other moldable material must be mechanically displaced between the positive standoff elements of the upper mold member, the prior art methods of molding have significantly greater energy requirements than the molding method of the present invention disclosed herein.
Additionally, it is often beneficial to manufacture panels of thermoplastic resin which have one or more generally solid sections, that is, sections exhibiting roughly the same characteristics as a solid panel, such as continuous outer surfaces. However, with existing molding methods described in the prior art, it is generally not possible to mold large-size panels or other items having one or more portions of solid thermoplastic resin, particularly when said solid portions are situated immediately adjacent to one or more sections exhibiting cellular structure. Because a solid mass of thermoplastic material will general
Rogers Donald S.
Seaux Kenneth P.
Seaux Ores Paul
Anthony Ted M.
Kuhns Allan R.
OLS Consulting Services, Inc.
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