Forming plastic articles having strands by stretching
AssigneeP.L.G. Research Limited
InventorFrank B. Mercer
Life of this patent
Estimating the term…
Abstract
In order to make a non-planar plastics material article, a starting material has at least one ring of holes or depressions and is pressed so that the part which is within the ring is moved generally at right angles to the plane of the ring with respect to the part which is outside the ring, thereby stretching, into orientated strands, zones between adjacent holes or depressions in the ring; in the finished article, the strands interconnect the two parts.
Claims13
A method of making a plastic material article, comprising providing a piece of plastic starting material having a plurality of generally coaxial rings of holes or depressions therein, each hole or depression being separated from its adjacent hole or depression in the same ring by a zone, the sum of the cross-sectional areas of all the zones in a given ring being approximately equal to the sum of the cross-sectional areas of each other ring, the cross-sectional area of each zone being the multiplication product of (a) the shortest distance between adjacent holes or depressions and (b) the average thickness of the plastic starting material along that distance, said piece being substantially all at substantially the same temperature, and moving a first part of said piece which is within the rings with respect to a second part which is on the other side of the rings, in a direction generally at right angles to notional planes which generally intersect the holes or depressions of the respective rings, thereby stretching said zones of said given and other rings into oriented strands, said zones in the given ring all being stretched to substantially the same stretch ratio and said zones in the other rings all being stretched to substantially the same stretch ratio.
A method of making a plastic material article, comprising providing a piece of plastic starting material having a plurality of generally coaxial rings of holes or depressions therein, the sum of the shortest distances between each respective pair of adjacent holes or depressions in a given ring being substantially equal to that in each other ring, and the plastic starting material zones between adjacent holes or depressions of the given ring and other rings being all substantially of the same thickness, said piece being substantially all at substantially the same temperature, and moving a first part of said piece which is within the rings with respect to a second part which is on the other side of the rings, in a direction generally at right angles to notional planes which generally intersect the holes or depressions of the respective rings, thereby stretching said zones of said given and other rings into oriented strands, said zones in the given ring all being stretched to substantially the same stretch ratio and said zones in the other rings all being stretched to substantially the same stretch ratio.
Dependencies are inferred from the claim text.