Analysis of tool design and kinematics when machining a gear by power skiving

Abstract

Gears are one of the most common machine parts used for transmitting motion and torque. At the same time, they are among the medium-complexity parts. The reliability and cost of the finished product depend on the manufacturing performance and the quality of the resulting part. Of the various methods of gear machining, power skiving is increasingly being used by the world's leading enterprises. Over the past few decades, it has become a highly competitive gear manufacturing process. This is primarily due to advances in tool engineering and improvements in computer numerical control machines. This article reviews some of the main topics, including new tool designs and insights into process kinematics. This article provides a thorough review of literature and trends in developing new skiving tool designs. It shows a different approach to describing the cutting pattern to the conventional one, which corresponds to the actual kinematics of the power skiving process. During tool operation, the working, kinematic, or actual cutting angles undergo continuous variation. The magnitudes of these angles are governed by the direction of the cutting velocity vector rather than by the initial reference planes of the tool. It has been established that the actual rake angle on the lateral entering cutting edge of a skiving tooth becomes negative and varies along the entire cutting trajectory, thereby increasing the intensity of shear deformation on this edge. A similar effect is observed for the clearance angle on the lateral exiting cutting edge, which also attains a negative value, consequently leading to an increase in frictional forces along the flank surface. The combined influence of these adverse phenomena results in a substantial rise in the cutting force and, more critically, in accelerated wear at the skiver tooth tips. Each group of skiving cutters was analyzed, with emphasis placed on the advantages and disadvantages of each tool type. Taking this scheme into account, cutting processes using skiving cutters with different blade structures and geometries are analysed. The design shortcomings of combined super skiving cutters are analysed.