毕业设计(论文)外文资料翻译系 别： 机电信息系 专 业： 机械设计制造及其自动化班 级： 姓 名： 学 号： 外文出处: Int J Adv Manuf Technol 附 件： 1. 原文； 2. 译文 2013年01月Int J Adv Manuf Technol (2001) 17:649653 2001 Springer-Verlag London LimitedReal-Time Prediction of Workpiece Errors for a CNC Turning Centre, Part 1. Measurement and IdentificationX. LiDepartment of Manufacturing Engineering, City University of Hong Kong, Hong Kong This paper analyses the error sources of the workpiece in bar turning, which mainly derive from the geometric error of machine tools, i.e. the thermally induced error, the error arising from machineworkpiecetool system deflection induced by the cutting forces. A simple and low-cost compact measuring system combining a fine touch sensor and Q-setter of machine tools (FTSFQ) is developed, and applied to measure the work- piece dimensions. An identification method for workpiece errors is also presented. The workpiece errors which are composed of the geometric error, thermal error, and cutting force error can be identified according to the measurement results of each step. The model of the geometric error of a two-axis CNC turning centre is established rapidly based on the measurement results by using an FTSFQ setter and coordinate measuring machine (CMM). Experimental results show that the geometric error can be compensated by modified NC commands in bar turning.Keywords: Dimension measure; Error identification; Geo- metric error; Turning1. Introduction In recent years, ultraprecision machining has made remarkable progress. Some special lathes have been able to make ultra- precision machining, to less than a submicron and nanomicron tolerances a possibility. A common second approach is that the grinding is used to achieve a high level of dimensional accuracy after turning. However, the condition of the cutting tool (diamond) and workpiece (aluminium) have restricted the application of ultraprecision lathes. The second approach increases the number of machine tools and machining processes used 1, which results in an increase in the manufacturing cost. At present, most CNC lathes are equipped with a positioning resolution of 1 urm. Various machining errors in finish turning, however, degrade the accuracy to a level of approximately10 urm, so that when turning carbon steel, a machining error predictably arises in excess of 2030 urm. For improving mach- ining accuracy, the method of careful design and manufacture has been extensively used in some CNC lathes. However, the manufacturing cost based on the above method will rapidly increase when the accuracy requirements of the machine tool system are increased beyond a certain level. For further improv- ing machine accuracy cost-effectively, real-time error prediction and compensation based on sensing, modelling and control techniques have been widely studied 2, so ultraprecision and finish tuning can be performed on one CNC lathe. The positioning resolution of the cutting tools and workpieceis reduced so that it cannot maintain high accuracy during machining because of the cutting-force-induced deflection of the machineworkpiecetool system, and the thermally induced error, etc. In general, a positioning device using a piezo-eletric actuator is used to improve the working accuracy, but the method introduces some problems, such as, the feedback strat- egy, and the accuracy of sensors, which add to the manufactur- ing cost of the products. However, if the workpiece error can be measured by using a measuring instrument, or predicted by using a modelling, the turning program produced by modified NC commands can be executed satisfactorily on a CNC machine tool. Thus, a CNC turning centre can compensate for the normal machining error, i.e. the machine tool can machine a product with a high level of accuracy using modified NC commands, in real time. The workpiece error derives from the error in the relative movement between the cutting tool and the ideal workpiece. For a two-axis turning centre, this relative error varies as the condition of the cutting progresses, e.g. the thermal deflection of the machine tool is time variant, which results in different thermal errors. According to the various characters of the error sources of the workpiece, the workpiece errors can be classified as geometric error, thermally induced error, and cutting-force- induced error. The main affecting factors include the position errors of the components of the machine tool and the angular errors of the machine structure, i.e. the geometric error. The thermally induced errors of the machine tool (i.e. the thermal error), and the deflection of the machining system (including the machine tools, workpiece, and cutting tools) arising from cutting forces, are called the cutting-force error. This pap