Synthesis of a Profile Errorless Involute Shaper Cutter with Cylindrical Rake Face

This paper presents a new geometric construction of a straight teethed involute shaper cutter having theoretical zero profile error. The usual shaper cutters are generated with classical, straight profiled, rake-type tools, applying them a linear decreasing profile shifting. Thus they result with a constant tooth height but with helical involute side relief faces. Due to the fact rake face is a circular cone, the cutting edge results in a spatial curve whose projection in a plane perpendicular to the axis differs from the involute curve; the difference is the theoretical profile error. The solution analyzed in this paper starts from a theoretical perfect straight involute tooth. The rake faces are separate for each tool; their form is cylindrical. The side relief faces are helical, in order to allow a positive side relief angle; the linear decreasing of the profile shifting coefficient is a consequence of this. The paper focuses on the geometric model of the proposed cutter shaper. It states all the necessary computing formulae for a design process. Parametric equations of the edges, the side relief faces and the addendum relief faces are given.