IN THE DRAWING
FIG. 1 is an isometric view of a blanket and anvil assembly illustrating an axial array of blankets attached to an anvil according to an embodiment of the present invention;
FIG. 2 is a fragmented sectional elevation view through one of the blankets of FIG. 1 in the typical flat uninstalled state showing the liner and molded plastic sheet blanket material;
FIG. 3 is a sectional elevation view of the mating locked abutting ends of a representative blanket assembly attached to the anvil as employed in the embodiment of FIG. 1;
FIG. 4 is a top plan view of the dimpled sheet metal liner that is attached to the blanket assemblies of FIGS. 2 and 3;
FIG. 5 is a top plan view of one of the dimples of the liner of FIG. 4 taken at region 5;
FIG. 6 is a a sectional elevation view of the liner of FIG. 5 taken at lines 6-6; and
FIG. 7 is a fragmented sectional elevation view of the liner in a mold for molding the blanket-liner assembly.
In the drawings, preferred embodiments of the present invention are illustrated wherein like parts are designated with like reference numerals. These drawings are diagrammatic and actual parts may differ from the drawings in scale and shape.
In FIG. 1, anvil and blanket assembly 10 comprises a steel circular cylindrical die cutter anvil 6 that has an axially extending channel 8 in the surface thereof for the length of the anvil. The anvil is rotated about longitudinal axis 14 by an apparatus (not shown) via an anvil shaft 12.
Attached to the anvil 6 is an axial array of blanket-liner assemblies 16. In FIG. 2, representative blanket assembly 16 comprises a plastic thermoset molded sheet material die cutter member 20 attached to a steel sheet liner 22. The liner 22 is of conventional sheet steel as used in this art. The liner 22 is molded to the member 20 in a conventional molding apparatus (not shown) such that the member 20 is adheringly bonded to the liner. The liner 22 has an array of stamped upstanding dimples 24 forming an array of convex-concave dome shaped projections.
In FIG. 4, the liner 22 is elongated and rectangular. The length (left to right in the figure) and width (top to bottom of the figure) of the liner matches that of the cover 20. The length is sufficient for the blanket assembly 16 to wrap about the anvil 6 and lock to the anvil channel 8 in a conventional manner. When so wrapped the edges of the respective ends 26, 28 of the blanket assembly 16 abut at seam 30, FIG. 3, to form a continuous smooth die cutting outer work surface 26. The width of the representative blanket assembly 16 is generally about a foot (30.5 cm).
In FIG. 4, the liner 22 has an array 32 of the dimples 24. The dimples 24 are identical in this embodiment, but may differ from each other in other implementations. The array 32 comprises an array of three rows 34, 36 and 38 of dimples 24. The dimples 24 in each of the three rows are equally spaced from each other in the corresponding row in this embodiment, but may have different spacing in other embodiments. The spacing between dimples in all of the rows is preferably the same. The spacing between the rows may differ. The dimples are preferably identical, but they may differ in dimension and shape in other embodiments. Also the dimples while convex-concave dome shaped in this embodiment, may have other shapes such as polygon, cubic triangular and so on as long as the shape of the dimples permits the plastic material to flow around and full encapsulate the liner during molding as described below The volumes contained by the dimples may also be of different values and shapes in different sheet metal liners and also may differ from each other in a given liner as long as the liner becomes encapsulated during molding of the blanket assembly. There is no criticality in size or shape of the dimples 24 except to permit the plastic material during molding to flow around the dimples to encapsulate the liner 22 as described below.
In FIGS. 5 and 6, preferably the dimples 24 are circular semi-spherical dome shaped as shown. The dimples 24 preferably have a representative maximum outer diameter d at their base regions, FIG. 5, of about ⅝ inches (about 16 mm) and an external height h of their convex domes above the surrounding liner surface plane, FIG. 6, of about 0.08 to about 0.09 inches (about 2 mm to about 2.3 mm). However, these dimensions are given by way of example for the disclosed embodiment and may vary from these values in other embodiments. The liner 22 preferably is sheet steel having a thickness of about 0.017-0.021 inches (0.4-0.5 mm). The dimples have smooth outer convex and inner concave spherical surfaces to permit the plastic material to readily flow around the dimples without gaps.
In FIG. 7, a portion of a mold 40 is shown having an interior mold surface 42. In the prior art molding of the liner blanket assemblies, the sheet metal liner is positioned abutting the mold surface 42 with no spacing therebetween. As a result no plastic material is permitted to flow between the liner and the mold surface 42. However, as shown in FIG. 7, the upstanding outer convex surface 44 of the dimples 24 of the liner 22 abut the mold inner surface 42. This abutment of the dimples against the surface 42 of the mold 40 creates a gap 46 between the liner 22 and the mold surface 42.
During the molding process when the plastic sheet die cutter member 20 is being molded, the molten plastic material in the mold is able to flow into the gap 46 between the liner 22 and the mold surface 42. Thus plastic material forming the member 20 is contiguous with the liner on the liner surface 48, FIG. 7, and a portion of the plastic material flows into the gap 46 between the liner 22 and the mold surface 46 to form a plastic layer 50, FIG. 2. The plastic layer 50 covers substantially all of the outer surface of the liner encapsulating the liner in combination with the molded plastic sheet member 20. While some plastic material may not fully cover some or all of the dimples, this is acceptable. The layer 50 in practice almost fully if not entirely, covers the liner to encapsulate it.
Applicants have discovered that by encapsulating the liner with the plastic material layer 50 and with the molded member 20, the molded member 20 and liner 22 assembly exhibit greater bending flexibility than an assembly molded without the layer 50 and without the encapsulation as in the prior art. This greater flexibility permits an installation person to more easily bend the blanket assembly 16 when wrapping it about and securing it to the anvil. This results in less fatigue of the installer and a quicker installation than with prior art blanket assemblies.
Thus the shape, dimensions, spacing of the projections permitting the encapsulation of the liner to the sheet member 20 is only important to the extent that the liner can be encapsulated during the molding process and does not have such molding defects that would interfere with the operation of the blanket assembly or its life. The present inventors do not contemplate any particular shape, size or configuration of the projections that would so detract from the operation or life of the blanket assembly.
In FIG. 3, anvil 6 has channel 8 as described above. Blanket assembly 16 is arranged with interlocking fingers 52 and 54 which lie in the plane 56 of the blanket and coextensive therewith. Such fingers are shown for example in U.S. Pat. No. 4,791,846 incorporated by reference herein. However, in this patent movement is permitted between the blanket and the anvil head during operation In the present embodiment such relative movement is not desired.
To lock the blanket assembly 16 in place to preclude relative movement to the anvil 6, a locking projection 58 depends from end 26 of assembly 16. The projection 58 depends from the fingers 52 and 54. The projection is integral with and is one piece with the blanket sheet member 20. The projection 58 is of the same shape as the channel 8 and extends for the length of the channel 8 into and out of the drawing figure. The projection 58 is dimensioned to fit in interference compressible friction engagement fit with the channel 8 in the transverse directions 60. This fit locks the projection 58 and the blanket assembly 16 to the anvil 6 precluding axial displacement of the blanket assembly 16 relative to the anvil 6.
It will occur to one of ordinary skill in this art that various modifications may be made to the disclosed preferred embodiments without departing from the spirit and scope of the invention. For example, the shape and dimensions of the dimples and of the sheet metal liner may differ from that described herein. The term encapsulated means encased in but not necessarily entirely encased without any exposure. Some external exposure is acceptable as long as the flexibility or bendable property of the molded plastic sheet material blanket is increased, i.e., the stiffness of the molded blanket plastic sheet material is decreased, by the encapsulation as compared to molded plastic sheet material with a liner that is not encapsulated. The disclosed embodiments are for illustration and not limitation. It is intended that the invention be defined by the appended claims.
Patent Application
20070251365
