Thermal Deformation Estimation of Under Composite Operating Conditions for a Ball Screw Feed Drive System

• Main Authors: Huan Hua Hsu, 許桓華
• Other Authors: 楊安石
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/frjxew

碩士 === 國立臺北科技大學 === 能源與冷凍空調工程系碩士班 === 103 === The position error of a feed drive system was primarily caused by the thermal deformation of a ball screw shaft. A high-speed ball screw system can generate massive heat after long-term operations, with greater thermal expansion produced, and thereby unfavorably impact the positioning accuracy of the feed drive mechanism. In this study, we applied the computational approach using the finite element method (FEM) to simulate the thermal expansion process for estimating the deformation of the ball screw system. In the model, the deformation of the ball screw shaft was modeled by a linear elasticity manner given the assumption that the material was elastic, homogeneous, and isotropic. To emulate reciprocating movements of the nut at the maximum speed of 10, 20, and 40m/min relative to the screw shaft, we also utilized a three-dimensional unsteady heat conduction equation to determine the steady-state and transient temperature distributions, as well as temperature rises for calculating the thermal deformations of hollow ball screws under operating situations. The analysis adopted the multi-zone heat loads to treat the heat generation sources from the frictions between the nut, bearings and the ball screw shaft. In addition, simulations were conducted to appraise the influence of composite operating conditions in terms of different speeds (500, 1000 and 2000 rpm) as well as moving spans (500 and 900 mm) of the nut on the thermal deformations of a ball screw shaft.