Stock material or miscellaneous articles – Sheets or webs edge spliced or joined – Sheets or webs coplanar
Patent
1985-04-01
1986-05-06
Van Balen, William J.
Stock material or miscellaneous articles
Sheets or webs edge spliced or joined
Sheets or webs coplanar
156 93, 156157, 156159, 156197, 156227, 156258, 428156, 428172, 428174, 428179, B32B 312, B32B 328, B32B 708
Patent
active
045871477
DESCRIPTION:
BRIEF SUMMARY
This invention relates to reticulated materials of substantially planar configuration which have been formed by the conjunction of a plurality of strips of nonplanar sheet material.
Such products are known in which the strips of nonplanar sheet material lie substantially perpendicular to the plane of the reticulated material so that the edges of the strips lie coplanar with the reticulated material and form opposite surfaces of it. In these materials, projections on the nonplanar sheets are opposed and brought into abutment to leave spaces between adjacent sheets and thus form the reticulated structure of the composite material. The abutted projections in these materials are permanently bonded to ensure shear strength between the strips.
One type of method and apparatus which may be used to form nonplanar sheets is that described, for example, in Australian Patent Specification No. 460,849. This specification describes the cuspation of nonplanar sheets through the action on a sheet of thermoplastic material of a patterned array of projections on opposed tools. The non-planar sheets formed in accordance with the disclosure of this specification have projections of substantially equal height extending from each surface of the sheet and are generally adapted to nest within sheets of similar configuration so that substantially the whole of the opposed surfaces of adjacent sheets are in contact. While the specification refers broadly to alternative sheet forms where the nesting of the sheets is limited by the pattern of the projections and the relative alignment of the adjacent sheets, any limitations on the form of such sheets and their relative configurations if nested in stacks of two or more do not appear to have been investigated.
Other forms and combinations of nonplanar sheets have been proposed but none are known which are any more relevant to the present invention than those of Australian Specification No. 460,849.
Cuspation forming technology has been found particularly useful for the production of sheets to be used in accordance with the present invention. This is at least partly because of the wide range of different patterns which may be formed using this technology and also because the technology allows the substantially continuous production of substantial lengths of nonplanar sheet material. Furthermore cuspation is a unique process in that it provides structurally efficient materials distribution while permitting variable vertical stretch. Accordingly it is useful to adopt and extend the terminology of the cuspation process in describing the present invention.
Bilateral cuspation by counter-thrust of opposed tools carrying cold projections draws hot thermoplastic sheet upwardly and downwardly forming cusps and inverted cusps. The cusp walls are formed by free stretch since the plan area of tool projections is usually less than 5% of the sheet plan area.
To define terms it is necessary to describe tooling principles. The position of the projections is based on a lattice or plane tessellation. This lattice can be triangular or preferably square.
For convenient description, the areas of the lattice may be considered as alternately black and white, as in a chessboard. The upper and lower opposed tools are then considered as two superposed lattices, black areas over black areas and white over white. On the lower tool at the centre of every "black" area is mounted a vertical projection. The upper tool has projections on the "white" area. In effect every up-projection lies between four down projections and vice versa, except at the lattice edges.
In the main example in Australian Patent Specification No. 460,849, all projections on both tool sets are of equal height. That is, the envelope of each tool set is a plane. Hot sheet placed between the tools is drawn only when the tool sets act to interdigitate their respective projections. As the tool projections are all of equal height, each surface of the sheet is deformed to the same extent by the interdigitation. That is, each projection forces the shee
REFERENCES:
patent: 3227598 (1966-01-01), Robb
patent: 3574109 (1971-04-01), Yoshikawa
patent: 3955019 (1976-05-01), Keith
patent: 4025996 (1977-05-01), Saveker
A.A.R.C. (Management) Pty. Limited
Van Balen William J.
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