Cutting – Other than completely through work thickness or through work... – Splitting
Reexamination Certificate
1999-05-18
2004-01-13
Dexter, Clark F. (Department: 3724)
Cutting
Other than completely through work thickness or through work...
Splitting
C083S176000, C083S425000, C083S435000, C083S435200, C083S856000, C425S289000, C425S335000, C425S362000, C425S373000
Reexamination Certificate
active
06675691
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to apparatus for continuously shaping the surface of a slab of compressible or cellular polymer material, such as polyurethane foam. A blade cuts portions of the compressible material from the surface of the slab after the slab is passed through a predetermined gap and has been compressed between a compression roller and a movable patterned platform. The predetermined gap preferably is created at a region where the platform is adjacent to or driven by a drive roller.
Several methods and apparatus for cutting slabs of cellular polymer materials have been disclosed in the prior art. For example, U.S. Pat. No. 4,700,447 to Spann discloses convolute-cutting slabs of polyurethane foam by compressing a slab or pad of foam between a pair of rolls with opposed spaced projecting fingers arranged in a pattern and cutting the foam with a saw blade transversely just as it emerges from the rolls. The cut slab is then separated into two pads each with convolute-cut surfaces forming a series of peaks separated by valleys. The valleys formed on one pad are formed by slicing away foam which becomes a mating peak or projection on the other pad. Spann then shaves the peaks to form a more planar top surface. As noted in Spann, convolute cutting alone produces only rounded peaks and rounded valleys, and it is difficult, if not impossible, to produce a cut surface with peaks having substantially flat top surfaces or with recesses having substantially straight side walls. The convolute usually is intended to form the classic symmetrical and repeating “egg crate” pattern of peaks and valleys. To achieve a planar upper surface at other than the recessed portions the tops of the peaks must be cut or shaped in a second step.
Compressible cellular polymer materials may also be cut using a hot wire cutter. A slab of such material is cut by moving the slab relative to one or more hot wires as shown, for example, in U.S. Pat. No. 4,683,791 (Demont). Only straight cuts in regular or symmetrical patterns may be formed using a hot wire cutter. See also U.S. Pat. No. 4,915,000 (MacFarlane) and U.S. Pat. No. 5,573,350 (Stegall).
Shapes may be cut into the surface of a slab of cellular polymer material using a punch cutting apparatus, such as disclosed in U.S. Pat. No. 5,299,483 (Ber-Fong). A block of the cellular material is pressed against a template so that a portion of the material is forced through an opening in the template. The exposed material is then cut by a blade and removed, leaving a recess or cavity in the slab. This method cuts one block of material at a time, and only one surface at a time.
U.S. Pat. No. 4,351,211 (Azzolini) compresses a block of foam material against a template or die having an aperture therein using a pair of plates with concave and convex portions. The compressed foam is transversely cut along the template as it is held between the plates. More complex cut regions may be obtained than when using a template without the plates with raised and depressed portions, but only one block is cut at a time. Other template or pattern cutting methods are shown in U.S. Pat. No. 3,800,650 (Schroder) and U.S. Pat. No. 3,653,291 (Babcock).
The surface of a cellular polymer material may be shaped by molding or embossing, as opposed to cutting. U.S. Pat. No. 4,383,342 (Forster), for example, discloses injecting the foam-forming composition into a mold cavity. After sufficient curing time, the individual foamed article is removed from the mold. Other one-shot molding techniques and apparatus are known to persons of skill in the art. The molded cellular polymer product generally forms a tough skin at the surfaces that were in contact with the mold.
Continuous and semi-continuous molding processes are also known. These processes have the same drawbacks associated with one-shot molding techniques. For example, U.S. Pat. Nos. 4,128,369 and 4,290,248 (Kemerer, et al.) disclose an apparatus and method for impression molding thermoplastic products. The thermoplastic material in a liquid state is injected between compressed traveling belt molds. As the belt molds travel away from the point of introduction of the thermoplastic, they are cooled, which in turns cools the thermoplastic material, allowing it to solidify. The hardened molded thermoplastic material is removed from between the belts to form the finished product. Kemerer does not show a method for cutting or shaping a cellular polymer material, such as polyurethane foam.
A method of embossing a foam surface using a patterned metallic embossing belt or band is shown in U.S. Pat. No. 4,740,258 (Breitscheidel). The foam is heated and then pressed against the embossing belt. The belt is removed after the foam surface cools. The embossed surface by design has a hardened skin. No method for cutting or shaping the foam is disclosed.
U.S. Pat. No. 5,534,208 (Barr) discloses a continuous rotary method for surface shaping synthetic foams in which the foam is compressed between a compression roller and a die roller having raised and recessed portions. The portions of the foam extruded into the recesses in the die roller are cut away. The compressed foam portions return to an uncompressed state after passing through the rollers. As a result, a mirror-image pattern to the pattern on the surface of the die roller is cut on the surface of the foam. The diameter of the die roller limits the length of the shaped synthetic foam article that may be formed.
The prior art does not disclose an apparatus for continuously shaping a compressible or cellular polymer material of unlimited length by cutting to form recesses of various depths and various symmetrical and nonsymmetrical shapes. Nor does the prior art disclose a profile cut product without the hardened skin or hard spots associated with molded or embossed products. Nor does the prior art disclose continuously cutting compressible or cellular polymer materials with an apparatus that includes a movable patterned platform, such as an endless belt or a series of connected panels defining at least one recess or void into which the cellular material may be compressed before cutting the material transversely with a knife blade.
SUMMARY OF THE INVENTION
An apparatus for continuously shaping a compressible or cellular polymer material, such as polyurethane foam, by cutting and removing portions of the material is disclosed. A compression roller and a cooperating surface, such as the surface of a driver roller, compress a slab of cellular polymer material. A surface of the moving patterned platform, interposed between the compression roller and the cooperating surface, defines one or more recesses or voids that hold a portion of the cellular material as it is compressed by the roller. In a preferred embodiment, the cooperating surface is the solid surface of a drive roller. In a less preferred embodiment, the moving patterned platform is interposed between the compression roller and a follower roller and the compression force is applied at a region where the platform is adjacent to a solid surface of the follower roller.
A knife blade is positioned downstream from the compression roller and the point at which the compression force is applied, preferably with the blade interposed between the compression roller and the patterned platform. The slab surface is cut transversely by the blade just as the slab emerges from between the compression roller and the moving patterned platform, thus trimming off those portions of the cellular material that filled the recesses or voids in the patterned platform. In an alternate embodiment, the blade is positioned so that it shaves a fine scrim layer of foam from the slab surface, and makes deeper cuts into the slab in the regions in which the polymer material has filled the recesses or voids, but preferably the blade cuts away foam material only from those portions of the surface at which it is intended that voids or recesses be formed. If the patterned platform defines upstanding projections, instead of or in addition to recesse
Connolly Bove & Lodge & Hutz LLP
Dexter Clark F.
Foamex L.P.
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