Patent ID: 8025832

Claim:
A method for shaping a thermoplastic material workpiece to a specified shape, having a softening point and at least one surface, the method comprising: supporting a workpiece of the thermoplastic material so that the at least one surface is spaced away from a mandrel having a shaped surface, the shape of which surface bears a relationship to the specified shape, thereby establishing a gap between the workpiece and the surface; flowing a fluid across the workpiece surface, establishing a predominantly viscous flow in the gap, which flow establishes a pressure profile across the workpiece surface such that force from the pressure inversely depends on the size of the gap; heating the workpiece to a temperature close to the softening point; while maintaining the fluid flowing across the workpiece surface such that the workpiece remains spaced away from the shaped surface, waiting until the workpiece conforms to the specified shape, due to the mandrel shaped surface and the fluid pressure profile; cooling the workpiece below the softening point so that it retains the specified shape.