On-Line Measurement Method for Diameter and Roundness Error of Balls

This paper presents an on-line measurement method for the diameter and roundness error of balls. An easy-installation rotary scanning system, which integrates the principles of the diameter and the roundness measurements, is constructed. The rotary scanning system consists of a rotary stage, a linear stage, and two sensors with a flat probe. Two sensors are initially installed on the linear stage and contact each other.The outputs of two sensors are reset to zero at first. The ball is then mounted on the rotary stage and positioned between two flat probes. The variations of the diameter and the roundness error of the ball at each angular position can be directly recorded by two sensors when the ball is rotated by the rotary stage. Substituting the outputs of two sensors into the proposed mathematical models, the diameter and roundness error can be evaluated. The effects of the alignment error induced by the spindle error of the rotary stage and the titling error and the eccentric error of the ball on the measurement accuracy can be self-separated in the proposed on-line measurement method. A series of experiments are carried out to verify the effectiveness and the capability of the proposed on-line measurement method and the designed rotary scanning system. The designed system is easy to construct both in the laboratory environment and the factory field. © 2020, International Society for Nanomanufacturing and Tianjin University and Springer Nature Singapore Pte Ltd.