The Thermal Characteristic Analysis Of The Spindle System Of The GMB2550 Gantry Boring-milling Machining Center

The machine tool is the basis of the machinery manufacturing industry, for its design and manufacturing level is a crucial criterion of national manufacturing industry. Currently, precision machining is the trend of the machine tool industry, and the fundamental way to improve the machining accuracy is to reduce processing errors, especially by the machine errors caused by thermal deformation. This dissertation focused on the spindle system of the GMB2550 gantry boring-milling machining center, and studies were mainly achieved as the followings:(1) This paper gave a brief introduction of the world-wide research on the thermal error of the machine tool, described the effects on machining accuracy caused by the temperature distribution, and sum up the research directions of the way to reduce the thermal error. Besides, the finite element method and the related software used for calculation and analysis were also introduced.(2) The finite element model of the spindle system was established. The thesis discussed the finite element method to solve the temperature field and the thermal stress distribution. The solid model built with Pro/E was imported into ABAQUS/CAE to obtain the assembly of the spindle system, and the parts' physical properties were defined as well as the their interactions. Additionally, the assembly was meshed.(3) The author determined the heat source and the transfer modes of the spindle system, set boundary conditions combined with actual working conditions, analysed the transient and steady-state temperature field with the finite element method, and modified the thermal property to ensure the accuracy of calculation through the comparison with the tested temperature data.(4) Based on the temperature distribution field, the thermal stress was analysed with the finite element method to calculate the thermal deformation of the spindle nose. On the terms of the thermal deformation inspection standards, the radial runout and the face runout impacted the machining accuracy significantly.(5) The essay optimized the spindle system, put forward effective measures, such as hoisting the asynchronous motor and so on, to reduce the thermal error, among which installing the cooling zone and setting the auxiliary heat source were particularly introduced. After optimization, the deformation of the spindle system was rapidly decreased, which guaranteed the machining accuracy.Aiming at the improvement of the thermal characteristics of the spindle system, this paper managed to reduce the thermal error and improve the machining accuracy, on the basis of the current research of the machine thermal error, which provided a technical reference and support to the thermal characteristics research of similar domestic large-scale machine tools.