METHOD AND APPARATUS FOR FORMING HIGH-IMPACT, TRANSPARENT, DISTORTION-FREE POLYMERIC MATERIALS

摘要

A method and apparatus are provided for forming a sheet (16) of polymeric material, such as polycarbonate. A forming mold (10) is provided having halves (12, 14) that engage for forming a heated sheet (16) therebetween. Each of the halves (12, 14) defines an interior cavity (18, 22) having a peripheral edge. The sheet (16) is retained between the peripheral edges (34-40, 52-58) of the halves (12, 14) and a vacuum (60) is generated within one of the cavities for drawing the sheet therein, whereby a sensing mechanism (80) detects a draw depth for initiating a cooling mechanism (20) to cool the sheet to a temperature below a glass transition temperature of the material. A series of retention mechanism (62) are provided about the peripheral edge of one of the halves (12, 14), for biasing the sheet (16) into engagement with the peripheral edge of the opposing half. A trimming mechanism (88) is further provided for trimming the perimeter of the sheet (16) to a desired form.