Patent ID: 7481958
Filing Date: 2009-01-27
Classification: B29C,B29L,B32B,B65D,E04C,Y10T

Abstract:
1. A method of producing the plastic sheet having a number of recessed and protruded parts produced by thermal processing to form a number of uneven parts consisting of a protruding, truncated cone-shaped part and a recessed, ring-shaped part surrounded and continuing from the protruding part on a plane of a plastic sheet, comprising the steps of: feeding a plastic sheet in the molten state extruded from a T-die to a vacuum forming roll, which rotates around an axis at a center of the vacuum forming roll and has plural projections and ring-shaped recesses each surrounding the projections and vacuum suction passages therein; forming plural protruded, truncated cone-shaped parts and recessed, ring-shaped parts surrounding and continuing from the protruding parts to have the parts evenly distributed on the plane of the plastic sheet, and peeling the formed plastic sheet from the vacuum forming roll.