Patent ID: 7319913

Claim:
A device for extracting an unmachined shape with respect to a product shape upon machining a product, comprising: a tool displacement unit for virtually displacing a machining tool corresponding to a selected point among predetermined points on a surface of a three-dimensional product shape model without causing interference between the product shape model and the machining tool by moving the machining tool in a direction vertical to the surface of the three-dimensional product shape model if interference between the product shape model and the machining tool occurs, thereby eliminating said interference; a distance detection unit for obtaining a distance between each of the predetermined points on the surface of the product shape model and corresponding projected points on the machining tool surface; and a three-dimensional shape preparation unit for preparing a three-dimensional unmachined shape by considering a shape of the machining tool surface using minimum values of the distances obtained regarding each of the predetermined points on the surface of the shape model and the corresponding points on the machining tool surface shape corresponding to a shape of the machine tool with the unmachined shape having cusps.