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热误差是精密机床最主要的误差源之一。主轴是机床的关键部件,其热误差直接影响机床的加工精度。文章以某型号精密卧式加工中心主轴为对象,对其温度场和热变形进行了仿真分析。根据仿真结果发现主轴轴向热变形更严重,并结合机床结构确定温度传感器布置位置。在此基础上,对不同转速下主轴部分位置温度和轴向热误差进行现场测试。运用最小二乘法建立热误差补偿模型,直接结合机床FANUC数控系统实施主轴轴向热误差补偿。经实验验证,补偿后主轴轴向热误差减小了85%以上。 相似文献
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主轴单元的热变形是高速加工中影响精度的主要因素。本文利用大型有限元分析软件ANSYS对高速电主轴进行了热-结构耦合分析。计算结果显示,设计的高速电主轴单元主轴轴承、主轴前端温升理想,工作端轴向热位移很小。这表明设计的电主轴具有良好的热-结构性能,可以满足加工精度要求。 相似文献
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Shuhe Li Yiqun Zhang Guoxiong Zhang 《International Journal of Machine Tools and Manufacture》1997,37(12):1715-1719
Thermally-induced errors are major contributors to the overall accuracy of machine tools. In this paper, an error pre-compensation system is developed to correct the thermal errors of the spindle and lead screws. A simple gauge 1-D ball array is used to accelerate and simplify the error measurement. An auto-regressive model based on spindle rotation speed is then developed to describe the thermal errors. Using the model, the thermal errors can be predicted without measuring the temperature field of the machine tool as soon as the workpiece NC machining program is made. By correcting the program, the errors can be pre-compensated before machining. Thus the process of compensation is greatly simplified and the cost is reduced. The test results on a vertical machining center show that a 70% reduction of thermal errors has been gained after compensation. 相似文献
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Tae Jo Ko Tae-weon Gim Jae-yong Ha 《International Journal of Machine Tools and Manufacture》2003,43(1):411
Thermally induced errors reduce the accuracy in precision machining, and a great deal of research has been presented on compensation for these errors in machine tools. However, during the transition period after commencing or stopping spindle rotation, thermal deformation behavior is very complex. In particular, the y-directional movement of the vertical machining center cannot be explained by thermal expansion alone because of the relationship between deformation and temperature. Thermal bending that is generated from the thermal gradient in the structure causes this movement. In the research described in this paper, a theoretical explanation and an experimental verification is given for the particular behavior of spindle thermal deformation. As it is not easy to map the relationship of the compensation model, separation of the steady from the non-steady state in the mapping process is strongly recommended. 相似文献
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The thermal behavior of a machine tool is an important indicator for the grade of production accuracy and indirectly for the
market success. The load-dependent temperature distribution and the resulting deformation of the machine tool are influenced
by a variety of design and thermo-technical parameters. The main spindle of a machine tool is, without any doubt, the major
heat source within the machine structure. The object of the scientific investigation presented in this article is the development
of an approach to robust compensation of thermo-dependent machine tool deformations due to spindle load in consideration of
rough machining. The focus of the work concentrates on the identification of the model with the highest compensation performance.
The underlying concept for the compensation of thermo-dependent machine tool deformations is the indirect approach by using
the speed and the effective power of the main spindle for the calculation of the Tool Center Point (TCP) displacement. The
presented modeling approach requires the knowledge of the TCP displacement in X-, Y- and Z-direction depending on the speed
and the effective power of the main spindle. As a tool for modeling the thermo-dependent behavior of a milling machine, a
load test rig for repeatable, defined long-term loading of the main spindle has been developed. It simulates the cutting force
depending on the spindle speed and the torque and applies load to the main spindle. The spindle speed and the spindle effective
power can be taken directly from the numerical control of the machine tool. An important advantage of the presented compensation
method is the fact that it does not require any external sensors. The displacement of the TCP has to be measured, but only
during modeling. The relationship between the speed/power of the main spindle as a cause and the displacement of the TCP in
X-, Y- and Z-direction as an effect can be determined by a transfer function. This paper compares the compensation results
depending on the transfer function and identifies the model with the best compensation performance. The validation of the
compensation method is executed by using the example of two different speed and power spectra of the main spindle. 相似文献
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龙门加工中心主轴滑枕结构是连接刀具和机床的一个重要部件,其受切削力和受热变形将直接影响刀具的加工精度.通过建立龙门加工中心主轴滑枕结构的有限元分析模型,在计算热源发热量以及主轴滑枕结构热边界条件的基础上,利用ANSYS有限元分析软件在其工作状态下进行切削力变形分析、稳态热变形分析以及热-结构耦合分析.得到了主轴不同转速条件下主轴滑枕结构热态性能及刀盘直径方向变形规律,为该型龙门加工中心主轴滑枕结构优化设计和热变形补偿提供了理论依据. 相似文献
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以精密车削中心主轴系统为研究对象,将有限元技术应用于其主轴系统的热特性研究,在机床热分析理论基础上,计算了液体动静压轴承内外壁的温度和主轴箱体的温度,建立并分析了主轴系统的稳态温度场和主轴的变形情况,为系统热补偿提供了理论依据. 相似文献
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Modeling of spindle-bearing and machine tool systems for virtual simulation of milling operations 总被引:2,自引:0,他引:2
Yuzhong Cao Y. Altintas 《International Journal of Machine Tools and Manufacture》2007,47(9):1342-1350
This paper presents a general, integrated model of the spindle bearing and machine tool system, consisting of a rotating shaft, tool holder, angular contact ball bearings, housing, and the machine tool mounting. The model allows virtual cutting of a work material with the numerical model of the spindle during the design stage. The proposed model predicts bearing stiffness, mode shapes, frequency response function (FRF), static and dynamic deflections along the cutter and spindle shaft, as well as contact forces on the bearings with simulated cutting forces before physically building and testing the spindles. The proposed models are verified experimentally by conducting comprehensive tests on an instrumented-industrial spindle. The study shows that the accuracy of predicting the performance of the spindles require integrated modeling of all spindle elements and mounting on the machine tool. The operating conditions of the spindle, such as bearing preload, spindle speeds, cutting conditions and work material properties affect the frequency and amplitude of vibrations during machining. 相似文献
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Measurement of spindle thermal errors in machine tool using hemispherical ball bar test 总被引:3,自引:1,他引:2
Seung-Han Yang Ki-Hoon Kim Yong Kuk Park 《International Journal of Machine Tools and Manufacture》2004,44(2-3):333-340
The assurance of top-quality products in machining processes requires improved machine tool accuracy. Among the various errors related to machine tools, thermal errors of a spindle have a significant effect on machining accuracy and directly influence both the surface finish and the geometric shape of the finished workpiece. Accordingly, the current paper proposes a new measurement method for spindle thermal errors in a machine tool based on the use of a ball bar system instead of the conventional capacitance sensor system. The novel measurement method is more efficient and easier to use compared to conventional measurement systems. Furthermore, a single ball bar system is sufficient for the simultaneous measurement of both geometric and thermal errors. 相似文献
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《CIRP Annals》2020,69(1):97-100
The dynamic behaviour of milling processes can be analysed using process simulations based on measured frequency response functions. However, the determination of these functions for micro-milling processes is challenging due to small tool diameters of 1 mm or less, the influence of higher spindle speeds on the dynamic behaviour, and runout errors. Therefore, an approach for analysing micro-milling tools based on an excitation using bearing balls with a diameter of 1 mm, shot by compressed air, is presented. The measured dynamic response is applied to a geometric physically-based process simulation in order to analyse tool vibrations in a micro-milling process. 相似文献
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Fast calibration and modeling of thermally-induced machine tool errors in real machining 总被引:2,自引:0,他引:2
J.-S. Chen 《International Journal of Machine Tools and Manufacture》1997,37(2):159-169
Calibration and modeling of thermally induced errors is a critical part of enhancing machine accuracy by software error compensation. In most applications, parametric thermal errors of a machine tool are calibrated and modeled individually by air-cutting experiments. Calibrating thermal errors individually is time-consuming and may neglect thermal interaction among thermal sources. The accuracy of the air-cutting model in real machining is also questionable. In this report, thermal errors of multiple machine axes in real cutting were calibrated simultaneously by a quick set-up measurement system consisting of on-machine probes and artifacts. Characteristics of thermal errors in real cutting under different cutting conditions, cutting paths and workpiece materials were investigated. It was found that thermal errors in real machining were distinct from those in air cutting. 相似文献
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以TH6350卧式加工中心为研究对象,构建了一套基于虚拟仪器系统的加工中心主轴系统温度场和热误差测量系统,测出了加工中心主轴系统的温度场和各项热变形.建立了基于I-DEAS的加工中心主轴系统的温度场和热变形有限元模型,得到了主轴系统的温度场和热变形分布及其计算结果,计算结果与实测值得到了较好的吻合,研究结果为加工中心的改进设计、温度控制和误差补偿提供了理论依据. 相似文献