Plastic and nonmetallic article shaping or treating: processes – With step of cleaning – polishing – or preconditioning...
Reexamination Certificate
1999-12-16
2001-06-19
Kuhns, Allan R. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With step of cleaning, polishing, or preconditioning...
C249S112000, C264S225000, C264S337000, C264S338000, C264S328180
Reexamination Certificate
active
06248271
ABSTRACT:
TECHNICAL FIELD
This invention relates in general to molding processes for molding construction materials. More particularly, this invention pertains to molding a roof covering of the type suitable for providing an aesthetically pleasing appearance and a high degree of weatherability when applied to the roof of a building.
BACKGROUND OF THE INVENTION
Conventional roof coverings for sloped roofs include asphalt shingles, wooden shake shingles, sheet metal, slate, clay and concrete tile. Clay and slate are advantageous because of their high weatherability and desirable appearance. Various parts of the world have local or regional architectural preferences for the appearance of a roof. In Europe, clay tile and slate are generally preferred over the relatively flat looking asphalt shingle. Tastes in the U.S. vary, with the western and southwestern part of the U.S. preferring clay tile or wooden shakes and shake shingles.
One of the problems with clay tile and slate roofs is that the clay and slate tiles must be carefully fastened individually to the roof, and therefore they are expensive to install. Also, clay and slate tiles are inherently fragile, and suffer much breakage during manufacturing, shipping and installation. These materials are fragile even after installation on the roof, and can be damaged by foot traffic on the roof. One of the problems with wood shake shingles is that they are not naturally fire resistant, and therefore are prohibited in certain fire-prone areas, or at least require treatment for fire resistance.
Molded plastic shingles have been developed as an alternative both to clay and slate tiles, and to wooden shake tiles. U.S. Pat. No. 5,615,523 to Wells et al., which is herein incorporated by reference, discloses such shingles. Typical compositions include about 20 percent resinous material and about 80 percent fine stone filling and glass fiber reinforcement, with minor amounts of additives. This class of materials is also known as polymer concrete or highly filled resin. The high percentage of filler is important for maintaining a high fire resistance. Typically, these highly filled plastic shingles are compression molded, although casting, injection molding, injection compression molding, and transfer molding can also be used.
In general, the wear surfaces of compression molds are relatively durable where the moldable material is a typical fiber reinforced plastic (FRP) material. However, when the moldable material is highly filled with an inherently abrasive filler material, as is the case with the highly filled plastic material used to mold roofing shingles and tiles, the mold surfaces can wear out at a relatively rapid rate. Erosion of the mold cavity surface necessitates removal of the mold for refurbishing. This is a time consuming and expensive process.
It would be advantageous if there could be developed a molding process that uses relatively inexpensive facings or inserts so that when the molding surface wears out the surface can be replaced by a fresh insert without replacing the whole mold. Further, such a molding process would improve upon the conventional milling and machining methods used in imparting the desired surface features into the surface of mold. Also, it would be beneficial if a method for producing the mold inserts could be developed. Such a method would eliminate the need for an expensive milling process to prepare the molding surface in the inserts.
SUMMARY OF THE INVENTION
The above objects as well as other objects not specifically enumerated are achieved by a method of molding roofing shingles, comprising the steps of providing a compression mold having two mold bodies, and installing a mold insert in each of the two mold bodies. The surfaces of the inserts are shaped to correspond with the desired shape of a roofing shingle. A multiplicity of roofing shingles are molded using the compression mold. Each molding step includes charging the mold with a moldable material containing resin in an amount within the range of from about 10 to about 40 percent, and filler material in an amount within the range of from about 60 to about 90 percent, wherein the filler material subjects the inserts to wear by abrasion. The inserts in the mold are replaced when they are worn out, but this is done without replacing the mold bodies.
In another embodiment of the invention, there is provided a method of molding roofing shingles comprising the steps of providing a compression mold having two mold bodies, and installing a mold insert in each of the two mold bodies, with the surfaces of the inserts being shaped to correspond with the desired shape of a roofing shingle. A multiplicity of roofing shingles are molded using the compression mold, wherein each molding step includes charging the mold with a moldable material containing moldable resin in an amount within the range of from about 10 to about 40 percent, and filler material in an amount within the range of from about 60 to about 90 percent. The filler material subjects the inserts to wear by abrasion, and the inserts in the mold are replaced when they become worn. The mold inserts are produced by casting them from metal according to steps including providing a pattern element of pattern material corresponding to the roofing shingle, coating the pattern element with a first layer of ceramic coating, and drying the first layer of ceramic coating. Subsequent layers of ceramic coating are added, and each layer is dried before another subsequent layer is added, to form a ceramic coated pattern element. The pattern material is removed from the ceramic coated pattern element to form a mold of ceramic material having a mold cavity corresponding to the roofing shingle. The mold of ceramic material is heated to a temperature suitable for molding an insert. Molten metal is introduced into the ceramic mold cavity. Finally the ceramic mold and the metal are cooled, and the ceramic material is removed to form a metallic mold insert having a surface corresponding to that of the roofing shingle.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings.
REFERENCES:
patent: 2584109 (1952-02-01), Blackburn et al.
patent: 2714226 (1955-08-01), Axelrad
patent: 3550213 (1970-12-01), Ormsby et al.
patent: 3632278 (1972-01-01), Hall et al.
patent: 3638299 (1972-02-01), Garner et al.
patent: 3723584 (1973-03-01), Nussbaum
patent: 3754499 (1973-08-01), Helsman et al.
patent: 4028450 (1977-06-01), Gould
patent: 4117060 (1978-09-01), Murray
patent: 4225109 (1980-09-01), Yotsutsuji et al.
patent: 4240780 (1980-12-01), Carcey
patent: 4551084 (1985-11-01), Lake
patent: 4604141 (1986-08-01), Natori et al.
patent: 4614630 (1986-09-01), Plium, Jr.
patent: 4656722 (1987-04-01), Armstrong
patent: 4659056 (1987-04-01), Michaud-Soret
patent: 4824628 (1989-04-01), Curfman
patent: 4834929 (1989-05-01), Dehoff et al.
patent: 4976400 (1990-12-01), Martell et al.
patent: 5061427 (1991-10-01), Hirzel
patent: 5156754 (1992-10-01), Nomura et al.
patent: 5176839 (1993-01-01), Kim
patent: 5307604 (1994-05-01), Tasso
patent: 5545366 (1996-08-01), Lust et al.
patent: 5580507 (1996-12-01), Williamson et al.
patent: 5615523 (1997-04-01), Wells et al.
patent: 5630305 (1997-05-01), Hlasnicek
patent: 5678162 (1997-10-01), Barlow et al.
patent: 5711126 (1998-01-01), Wells
patent: 5800747 (1998-09-01), Cavasin
patent: 5800752 (1998-09-01), Charlebois
Ashley, Mechanical Engineering, Rapid Mold-Making for Investment . . . , (Nov. 1992).
Alloy Digest, Viscount 44, Data On World Wide Metals . . . , (Sep. 1960).
Graham William David
Rudy Andy
Schelhorn Jean E.
Dottavio James J.
Eckert Inger H.
Kuhns Allan R.
Owens Corning Fiberglas Technology Inc.
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