SURFACE SHAPING OF COMPRESSIBLE CELLULAR POLYMERS WITH CONTINUOUS ROTARY APPARATUS
Apparatus and methods for cutting compressible cellular polymers such as polyurethane foam, are characterized by a first die roller and a pressure roller, wherein both rollers define raised portions separated by recesses or depressions, and the raised portions on the first die roller register with the recesses of the pressure roller at a nip formed between the rollers. Portions of the polymer material extruded into the spaces between the raised portions of the first die roller are cut away, such that the cut product conforms substantially to the surface geometry of the first die roller, and the depth of cut is greater than with prior rotary cutting methods.
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This application is a divisional of U.S. Ser. No. 10/997,041, filed Nov. 23, 2004, now U.S. Pat. No. ______.
FIELD OF THE INVENTIONThe present invention relates to apparatus and methods 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 has been compressed between complementary patterned surfaces, such as die rollers. The concurrent positive and negative compression imparted by the surfaces on the compressible material results in particularly desirable deeper vertical cut surfaces with flattened valleys or troughs.
BACKGROUND OF THE INVENTIONSeveral methods and apparatus for cutting slabs of cellular polymer materials have been disclosed in the prior art. Of particular interest is U.S. Pat. No. 5,534,208 (Barr). This patent discloses a continuous rotary method for surface shaping synthetic foams in which the foam is compressed between a smooth 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 by a blade. 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. It can be difficult to produce troughs with flattened bottom surfaces using this rotary method. Moreover, the depth of cut is proportionate to the die roller pattern depth. See also, U.S. Pat. No. 5,688,538.
Heretofore, it has been difficult to form foam parts having deep cut portions, e.g., up to 80% of the thickness of the foam slab, using the continuous cutting method of the '208 patent. Such deep cut portions with relatively straight and relatively vertical side walls are also difficult to process. Thus, apparatus and methods for producing such foam parts are desired.
SUMMARY OF THE INVENTIONIn a first aspect, a sheet or pad of a cellular polymer material, such as a foam, having a three-dimensional shaped support surface with raised portions separated by depressions is formed by pressing a slab of the cellular polymer material that has a planar surface into a nip formed between a die having a cylindrical die surface with raised die portions separated by die depressions and a pressure roller parallel to said die surface. The pressure roller defines recesses of complementary shape to said raised die portions wherein each recess substantially registers with a respective raised die portion at the nip. Each raised die portion may nest into the respective registered recess in the pressure roller. At least one of said die and said pressure rollers is turned. Some portions of the cellular polymer material are compressed against said raised die portions to a reduced thickness and other portions of the cellular polymer material are extruded into said die depressions. The extruded portions are then cut away by a blade.
Preferably, the cutting blade is positioned in a cutting plane substantially tangent to the cylindrical die surface. The resulting pad then has raised portions separated by depressions in which the raised portions have substantially vertical side walls. In addition, the resulting pad has raised portions separated by depressions in which the depressions have substantially planar bottom surfaces.
In a particularly preferred embodiment, the raised portions of the pad have a height that is at least 50%, more preferably at least 80%, of the thickness of the pad.
In a second aspect, an apparatus for forming a sheet or pad of a cellular polymer material, such as a foam, having a three-dimensional shaped support surface with raised portions separated by depressions includes a die having a cylindrical die surface with raised die portions separated by die depressions and a pressure roller parallel to said die surface. The pressure roller defines recesses of complementary shape to said raised die portions wherein each recess substantially registers with a respective raised die portion at a nip formed by the die roller and the pressure roller. Each raised die portion may nest into the respective registered recess in the pressure roller. At least one of said die and said pressure rollers is turned. Some portions of the cellular polymer material are compressed against said raised die portions to a reduced thickness and other portions of the cellular polymer material are extruded into said die depressions. The extruded portions are then cut away by a blade.
Numerous other objects, features and advantages of the invention shall become apparent upon reading the following detailed description taken in conjunction with the accompanying drawings, in which:
With reference to the drawings in which like numerals designate similar elements,
The compression roller 14 is mounted for rotation on shaft 22. The compression roller 14 may be indexed so that its circumferential surface is closer to or farther away from the outer circumferential surfaces of the rings 18 forming the die roller 12. In this way, the nip between the compression roller and the die roller may be varied. The shafts 16, 22 are mounted for rotation to a supporting structure, such as a housing (indicated by phantom outline in
A cutting blade (not shown) is installed so as to cut a slab of compressible material just as it emerges from the nip between the compression roller and the die roller. Referring to
Referring now to
While a honey-comb like regular pattern with hexagonal-shaped raised projections has been shown in
The die surface of the first die roller may be constructed either by machining a solid cylindrical roller body or by axially assembling a number of die rings on the roller shaft, each die ring carrying one circumferential row of die elements. The diameter, thickness and orientation of each ring may be varied to vary the shape of the cut product to be produced by the rotary cutting apparatus. The constructions of the die rollers shown in U.S. Pat. No. 5,534,208 are illustrative, and are incorporated by reference.
The first die roller 52 is mounted for rotation on shaft 56. Shaft 56 is positioned in parallel with shaft 62. If rings are used to form the die roller pattern surface, such rings may be attached to the roller with set screws. Holes may be tapped in an inner groove surface to receive the set screws. Other suitable attachment means may be used.
A pressure roller, which may be a second die roller 54, is mounted for rotation on shaft 62. The pressure roller 54 defines recesses 60 in its outer circumferential surface. Such recesses 60 for the embodiment illustrated in
Most preferably, the die roller 52 and pressure roller 54 are formed from one or more materials that are durable, sufficiently hard under compression and will not react with the cellular polymer material to be cut in the rotary cutting apparatus 50. Suitable materials for the first and second rollers 52, 54 include, inter alia, steel and aluminum.
The two shafts 56, 62 are spaced apart so that a gap exists between the outer circumferential surfaces of the first and second rollers 52, 54. This gap or nip is substantially smaller than the thickness of the slab 70. Preferably, where the cellular polymer material to be cut is flexible polyurethane foam in a slab with a thickness in the range of 2.5 to 15 cm, the nip spacing between the outer circumferential surfaces of the first and second rollers is from 5 to 75 mm, most preferably from 12 to 50 mm.
As the foam slab 70 is fed into the roller assembly 50 in the direction of arrow 68 shown in
In the embodiment of the cutting method shown in
As is apparent from
As an improvement over the cut support structures shown in U.S. Pat. No. 5,534,208, the slots 82 in the shaped support surface can be much deeper, while the slot bottom surface remains generally planar. Whereas the cut depth of the slots shown in
While preferred embodiments of the invention have been described and illustrated here, various changes, substitutions and modifications to the described embodiments will become apparent to those of ordinary skill in the art without thereby departing from the scope and spirit of the invention.
Claims
1. An apparatus for making a sheet or pad of a cellular polymer material having a three-dimensional shaped support surface with raised portions separated by depressions by pressing a slab of the cellular polymer material that has a planar surface into a nip formed between a die having a cylindrical die surface with raised die portions separated by die depressions and a pressure roller parallel to said die surface, turning at least one of said die and said pressure roller with a motor means, compressing some portions of the cellular polymer material against said raised die portions to a reduced thickness and extruding other portions of the cellular polymer material into said die depressions, and cutting away said other portions with a blade, characterized in that:
- the die has a length and a circumference, and the raised die portions are in multiple first rows along the length wherein each first row extends around the circumference of the die and comprises a plurality of discrete raised die portions and the raised die portions have face surfaces with an outer periphery defining a geometric shape, and wherein the each of the raised die portions also is in one of a multiple of second rows that extend along the length of the die, with each such second row containing three or more raised die portions, and
- the pressure roller has a length and defines a plurality of recesses in its outer circumferential surface that are in multiple first rows and multiple second rows along the length, wherein each first row extends around the circumference of the pressure roller and comprises a plurality of discrete recesses, with each recess having a perimeter of identical or substantially identical shape and size to the outer periphery of a respective one of said raised die portions, wherein each recess also is in one of the multiple second rows that extend along the length of the pressure roller, with each such second row containing three or more recesses, wherein each recess substantially registers with the respective raised die portion at the nip so that the outer periphery of each face surface is in alignment with the perimeter of the respective recess with which it is substantially registered, and
- wherein cutting away said other portions is with a blade positioned in a cutting plane substantially tangent to the cylindrical die surface.
2. The apparatus of claim 1, wherein the blade is positioned in a cutting plane substantially tangent to the cylindrical die surface.
3. The apparatus of claim 1, wherein each raised die portion of the die registers with but does not nest within a respective recess in the pressure roller.
4. The apparatus of claim 1, wherein each raised die portion of the die registers with and nests within a respective recess in the pressure roller.
5. An apparatus for making a sheet or pad of a cellular polymer material having a three-dimensional shaped support surface with raised portions separated by depressions, comprising:
- a die having a cylindrical die surface and a length and a circumference, and having raised die portions separated by die depressions, wherein the raised die portions are in multiple first rows along the length wherein each first row extends around the circumference of the die and comprises a plurality of discrete raised die portions and the raised die portions have face surfaces with an outer periphery defining a shape, and wherein the each of the raised die portions also is in one of a multiple of second rows that extend along the length of the die, with each such second row containing three or more raised die portions,
- a pressure roller parallel to said die surface and spaced apart therefrom to form a nip between an outer circumferential surface of the pressure roller and the cylindrical die surface, said pressure roller having a length and defining a plurality of recesses in its outer circumferential surface that are in multiple first rows and multiple second rows along the length, wherein each first row extends around the circumference of the pressure roller and comprises a plurality of discrete recesses, with each recess having a perimeter of identical or substantially identical shape and size to the outer periphery of a respective one of said raised die portions, wherein each recess also is in one of the multiple second rows that extend along the length of the pressure roller, with each such second row containing three or more recesses, wherein each recess substantially registers with the respective raised die portion at the nip so that the outer periphery of each face surface is in alignment with the perimeter of the respective recess with which it is substantially registered, and
- a cutting device positioned in a cutting plane substantially tangent to the cylindrical die surface and in or just beyond the nip for cutting away some or all of portions of said cellular material extruded into said die depressions when said pressure roller presses the slab against the die.
6. The apparatus of claim 5, further comprising a motor to rotate either or both of the die and the pressure roller.
7. The apparatus of claim 5, wherein each raised die portion of the die registers with but does not nest within a respective recess in the pressure roller.
8. The apparatus of claim 5, wherein each raised die portion of the die registers with and nests within a respective recess in the pressure roller.
Type: Application
Filed: May 12, 2011
Publication Date: Sep 1, 2011
Applicant: Foamex Innovations Operating Company (Media, PA)
Inventor: Jose D. M. Contreras (West Covina, CA)
Application Number: 13/105,971
International Classification: B28B 11/12 (20060101);