Study of Formed Milling Cutter for Processing Eccentric Screw Based on Non-Instantaneous Envelope Method

The design theory and method of formed milling cutter for eccentric screw is presented. Through analyzing the shape and characteristic parameters of eccentric screw, the spiral surface equation of eccentric screw was established. Considering the relative motion and the meshing conditions between formed milling cutter and eccentric screw, the contact line equation was established based on non-instantaneous envelope method. Further, from the cross-section shape of the rotary surface formed by the contact line around the axis of cutter, the profile equation of formed milling cutter was deduced. By analyzing the causes of processing errors after wear of formed milling cutter, the tooth back curve equation was achieved in accordance with spiral of Archimedes and got the profile equation of formed milling cutter with constant back edge was gotten. Finally, the interference for profile equation of formed milling cutter was checked. Simulation shows that the profile of formed milling cutter coincides with the spiral surface of eccentric screw and the designed profile equation of formed milling cutter conforms to the requirements of the processing. This work provides a theoretical foundation for the design and manufacture of formed milling cutter.