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It can beseen from the Table 1 that the maximum relative errorbetween the results of calculation and measure is10.71%. Here errors of calculating are mainly aroused inmodeling. In order to improve the accuracy of modeling,further work is concentrated on the hybrid modelingmethod of a whole machine-tool structure.7. Summary and conclusionsA systematic procedure was proposed to predict thedynamic behaviours of a whole machine-tool structurewith respect to natural frequencies. The prediction pro-cedure makes use of a receptance synthesis method,which incorporates the effects of non-linearity of joints.The dynamic modeling was developed by three types ofelements such as the distributed-mass beam, the lumpedmass and the joint.
As an example, the dynamic charac-teristics of a guideway joint are analysed based upon thedynamic fundamental characteristic parameters of jointsurfaces at unit area obtained by experiments. Since thedynamic fundamental characteristic parameters of jointsurfaces at unit area are common for analysing dynamiccharacteristics of joints, the aim to predict dynamicbehaviours of a whole machine-tool structure at itsdesign stage can be realised. Table 1Comparison of the predicted and experimental natural frequencies for the tool-side structureOrders 1 2 3 4 5 6 7 8Measured results (Hz) 52 103 112 150 190 230 260 303Computed results (Hz) 48 106 124 140 186 250 270 282Relative errors (%) 7.69 2.91 10.71 6.67 2.10 8.70 3.85 6.93Based on the proposed procedures the software forpredicting the natural frequencies of a whole machine-tool structure was developed. The analysis of dynamiccharacteristics of joints in the software is supported bythe library of the dynamic fundamental characteristicparameters of joint surfaces at unit area.To demonstrate the utility of the proposed proceduresand the software, a dynamic test for a whole machiningcentre structure was carried out. The maximum relativeerror of the natural frequencies between calculating andmeasuring is 10.7%, which showed that the proceduresand the software can be used in predicting the naturalfrequencies of a whole machine-tool structure at itsdesign stage.AcknowledgementsThe authors are grateful to the State Key Project, forsupport of this research work under grant no. 85-719-04-04/02.References[1] J.A.W. Hijink, A.C.H. Van Der Wolf, Analysis of a millingmachine: computed results versus experimental data, in: Proc14th Int MTDR Conf, Pergamon, 1973, pp. 553–558.[2] S. Taylor, S.A. Toias, Lumped-constants method for the predic-tion of the vibration characteristics of machine tool structures, in:Proc 5th Int MTDR Conf, Pergamon, 1964, pp. 37–42.[3] H. Sato, Y. Kuroda, M. Sagara, Development of the FEM forvibration analysis of machine tool structure and its application,in: Proc 14th Int MTDR Conf, 1973, pp. 545–552.[4] W.P. Fu, Y.M. Huang, G.P. Zhang, Experimental investigation ondamping behaviors of normal joint surface at unit area, Modeling,Measurement and Control B, AMSE Press 51 (2) (1993) 13–20.[5] C.F. Beads, Damping in structural joints, The Shock andVibration Digest (6) (1982) 563–570.[6] M. Weck, K. Teipel, Dynamisches Verhalten Spanender Werk-zeugmaschinen, Springer Verlag, Berlin, 1977.[7] M. Yoshihara, Computer-aided design improvement of machinetool states Incorporating joint dynamics data, Annals of the CIRP28-1 (1979) 241–246.[8] G.P. Zhang, Y.M. Huang, S.J. Wang, X. Yan, Modeling of thegeneral dynamics of machine tools with BP neural network, in:Proc the ICAIE’98, 1998, pp. 353–356.[9] R.E.D. Bishop, D.C. Jonson, The Mechanics of Vibration, Uni-versity Press, Cambridge, 1960.[10] Y.M. Huang, W.P. Fu, L.X. Dong, Research on the normaldynamic characteristic parameters of joint surface, Journal ofMechanical Engineering 29 (3) (1993) 74–77 In Chinese.
摘要本文提出一种预测机床结构的动态行为的系统化程序。预测程序利用刚-柔的合成方法，其中动态模型是由元素分布质量梁，集中质量和结合面组成。例如，动态特性的导轨结合面分析就是通过使用动态的基本特征参数联合表面单位面积上的实验来完成的。该预测软件是基于加工结构的动态行为基础上制定的程序来开发的。为了证明提出的程序和开发的软件的有效性，加工中心结构的动态建模已经建立，是利用其自然频率计算软件来完成的。动态试验表明，加工中心的程序和软件对机床结构设计阶段的动态行为的的预测是有效的。