METHOD FOR PROVIDING A WINDOW HOLE IN A CYLINDRICAL BLANK

摘要

PURPOSE:To provide a desired triangular window hole in the outer or inner peripheral surface of a blank by giving cutting feed to a rotary tool which forms a envelope surface of cylindrical or conical shape with its own rotation. CONSTITUTION:When a tool 1 which forms a cylindrical or conical envelope by its own rotation is fed while rotating, two surfaces 4, 5 are formed by the side face 2 and the bottom surface 3 of the tool 1. In this case the rotary axis of the tool 1 is tilted angle beta from the direction perpendicular to the axis of a blank 6 to cut the blank in parallel to the bottom surface of the tool and angle gamma from same axis to cut the blank. By this method the blank 6 is formed with a window hole 7 in which the length of arc is approximately in proportion to the distance between the apex and the arc.