Analysis of Form Error caused by Thermal Effect in Single Point Diamond Turning Machine

Abstract

In a single point diamond turning machine, the workpiece inevitably develops an uneven temperature field, leading to surface deformation and subsequently affecting the form accuracy. In this paper, a Twyman-Green interferometer is constructed to measure the thermal deformation of workpiece surfaces. An orthogonal experiment is designed, and the response surface methodology is employed to investigate the effects of spindle speed, cooling water temperature, cooling water flow rate, and air velocity on the thermal deformation of the workpiece. The result indicates that under the conditions of 4000 RPM spindle speed, 23℃ cooling water temperature, 5 L/min cooling water flow rate, and 3 m/s air velocity, the workpiece surface exhibits a protrusion with a higher center and lower periphery, and the amplitude of the protrusion at the workpiece center is 96 nm compared to the edges. The effects of rotational speed, cooling water temperature, and air flow rate on the thermal deformation of the workpiece are more pronounced, while cooling water flow rate has almost no influence. Furthermore, there exists a coupling relationship between the rotational speed and cooling water temperature. Specifically, for every 1% increase in rotational speed, cooling water temperature, and air flow rate, the thermal deformation of the workpiece increases by 1.51%, 2.38%, and 0.34% respectively.