共查询到20条相似文献,搜索用时 15 毫秒
1.
Thermal characteristics of the spindle bearing system with a gear located on the bearing span 总被引:3,自引:0,他引:3
Jin Kyung Choi Dai Gil Lee 《International Journal of Machine Tools and Manufacture》1998,38(9):1017-1030
High cutting speeds and feeds are essential requirements of a machine tool structure to accomplish its basic function which is to produce a workpiece of the required geometric form with an acceptable surface finish at as high a rate of production as is economically possible. Since bearings in high speed spindle units are the main heat source of total cutting system, in this work, the thermal characteristics of the spindle bearing system with a tilting axis were investigated using finite element method to improve the performance of the spindle bearing system. Based on the numerical results, a specially designed prototype spindle bearing system was manufactured. Using the manufactured spindle bearing system, the thermal characteristics were measured and compared to the numerical results. From the comparison of the numerical results with the experimental results, it was found that the finite element method predicted well the thermal characteristics of the spindle bearing system. 相似文献
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Thermo-mechanical model of spindles 总被引:9,自引:0,他引:9
This paper presents a Finite-Element-method-based thermo-mechanical model of spindles with rolling bearings. The heat generated in the bearings and the motor is transferred to the ambient air, the motor coolant and the spindle structure, and causes thermal expansion of spindle parts. The experimentally validated thermo-mechanical spindle model predicts temperature distribution and thermal growth, as well as bearing stiffness and contact loads, under specified operating conditions. Transient changes in temperatures, deformations, viscosity of the lubricant, and bearing stiffness are considered in the solution. The predicted bearing properties are used to estimate the changes in the dynamic behavior of spindles. 相似文献
3.
Igor Zverv Young-Shik Pyoun Keon-Beom Lee Jeong-Du Kim Inho Jo Andrew Combs 《Journal of Materials Processing Technology》2005,170(3):570-578
Kinematic characteristics and elastic deformation properties of ball bearings such as stiffness, axial, and radial deflections of the rings, speeds of balls, contact angles, and loads, all vary strongly with rotational speed, temperature, and axial preload. This paper presents an elastic deformation model of spindle units built into ball bearings, which are running on high rotational speed and axial preload. For this, software for simulation of the high speed spindle units was developed and introduced into a practical use. A computer aided analysis of the model was carried out and experiments were made, which showed a significant effect of high rotational speed, cutting load, bearing axial preload, and a new effect for which the criteria for a choice of bearing preload are given. 相似文献
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Jenq-Shyong Chen Kwan-Wen Chen 《International Journal of Machine Tools and Manufacture》2005,45(12-13):1487-1493
Angular contact ball bearings are the most popular bearing type used in the high speed spindle for machining centers. Because the bearing load is increased rapidly with the raised spindle speed due to the centrifugal force and temperature raise, proper initial preload and especially operating-induced load control of the angular ball bearing is important to the rigidity, accuracy and life of the spindle. The bearing layout, preload mechanism an on-line load bearing control are discussed in this paper. The management of the centrifugal force and thermally-induced bearing loads is especially emphasized. An active bearing load monitoring and control mechanism that consists of an integrated strain-gage load cells and piezoelectric actuators has been developed and tested. This active control and monitoring mechanism on-line adjusts the bearing load according the cutting conditions. Experiments were conducted to identify the proper initial bearing preload range. Optimal preload for the lowest bearing temperature raise existed for a specified spindle speed. The optimum preload, however, should be raised when the operational speed is increased. 相似文献
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A new concept for increasing process stability during milling processes is presented utilizing a parametric anti-resonance. The beneficial effect is examined by numerical calculations in the time domain for an example spindle which is supported conventionally by ball bearings and is equipped with an additional active magnetic bearing that enables the realization of a deliberate parametric excitation. In the present study the stiffness of this active support bearing is changed periodically with time. The parametric excitation is tuned to a parametric anti-resonance which triggers the transfer of vibration energy between the vibration modes of the underlying system without this additional time-periodicity. It is highlighted how vibration energy is transferred from the first bending mode of the rotor, which is the most critical one by means of regenerative chatter, to a mode with higher damping in order to increase the effective damping of the entire spindle drive unit. 相似文献
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针对由于撞刀事故引起的精密车床主轴精度下降问题,首先通过主轴振动信号监测,获取故障主轴振动信号频域特征;然后基于主轴结构和轴承特征参数,计算不同故障模式下轴承故障特征频率;最后基于故障特征频率与监测振动信号频率之间的对应关系,定位主轴故障位置。通过主轴拆卸和精度测试,验证了所提故障定位方法的有效性。实验结果表明:角接触球轴承内、外圈损伤是导致主轴精度下降的故障源,理论方法故障定位结果与拆卸实验定位结果一致;采用新轴承重装配后主轴的精度检测结果恢复正常,进一步验证了此故障定位方法的有效性。 相似文献
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Christian Brecher Christoph Baum Markus Winterschladen Christian Wenzel 《Production Engineering》2007,1(4):415-420
Hydrostatic bearings have an excellent static and dynamic behavior and are used for different kinds of application. Application of hydrostatic bearings is limited by friction and therewith by velocity. Typical characteristics of the hydrostatic system (load, stiffness, flow) are calculated without a velocity dependency. The geometry of the hydrostatic bearing pockets and their restrictors are optimized by using time continuous pressure distribution at the bearing pocket, laminar flow behavior as well as constant velocity of the bearing. The dynamic effects of the flow at high velocities are not considered. The paper reflects the common design and calculation methods and shows their limitations in regard to the calculation of hydrostatic bearings at high velocities. It analyzes the results of complex dynamic flow simulations of hydrostatic bearings and presents a new design and optimization concept of hydrostatic bearings. This concept analyses the oil flow at high bearing velocities and it optimizes the bearing geometry, the restrictor geometry as well as the geometry of the main mechanical components. 相似文献
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M. Aleyaasin R. Whalley M. Ebrahimi 《International Journal of Machine Tools and Manufacture》2000,40(6):809-822
In this paper a high precision grinding wheel is considered as a rigid rotor mounted on two hydrostatic bearings. The equations for small perturbations of the wheel on the bearings are derived in the form of a multi-input, multi-output transfer function matrix, enabling the frequency response function of the wheel to be determined. Thereafter an optimisation algorithm is proposed which considers speed, load and dimensions of the spindle, and computes optimal stiffness and damping of the bearings. The dynamic characteristics of the bearings, tuned for minimum radial displacement of the spindle, is achieved maximising thereby the accuracy of the grinding process. Simulation results show that by stiffness coarse adjustment, and fine adjustment of the damping in the bearings, a spindle with 35 μm manufacturing error, can produce components with 3 μm accuracy. 相似文献
13.
R.L. Judd K. Aftab M.A. Elbestawi 《International Journal of Machine Tools and Manufacture》1994,34(7)
The results of an experimental investigation into the practicality of using a heat pipe installed in the spindle of a milling machine to remove the heat produced in the spindle bearings which is capable of causing thermal distortion and cutting error are presented in the paper. Measurements of the variation of bearing temperature with time are reported at four different spindle speeds when there was no heat pipe installed, when the heat pipe was cooled by air and when the heat pipe was cooled by an ice/water mixture. Analysis of the results by a simple heat transfer model indicates that the particular heat pipe used was capable of removing up to 160 W with a corresponding 50% reduction in the rise of the bearing temperature above the temperature of the surrounding air at steady operating conditions. 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
15.
Young Kug Hwang Choon Man Lee 《International Journal of Machine Tools and Manufacture》2009,49(10):781-787
Machine tool spindles of late require high stiffness and fast rotation characteristics all at once for high-speed, high-efficient processing, as well as for a wide range of use rotation. As such, many studies are being carried out on automatic variable preload control methods that apply a preload to a spindle rolling bearing as an alternative to the existing fixed position preload and constant pressure preload methods. This paper introduces a newly structured automatic variable preload device that can automatically adjust the preload applied to spindles employing a rolling bearing. It proposes an automatic variable preload device with a completely new composition comprising of a main bearing to which the preload is applied, an auxiliary bearing that conveys the force and a centrifugal element that converts the centrifugal force into a force in the axial direction, and a constant pressure preload spring that applies the initial preload to the main bearing. Other changes in the centrifugal force are also presented. The proposed composition was validated through a contact nonlinear analysis, and the design data necessary to create a prototype were obtained. A prototype for the automatic variable preload device using centrifugal force was then created and tested to confirm that the preload device of the proposed structure runs properly and smoothly. 相似文献
16.
Expert spindle design system 总被引:8,自引:0,他引:8
Osamu Maeda Yuzhong Cao Yusuf Altintas 《International Journal of Machine Tools and Manufacture》2005,45(4-5):537-548
This paper presents an expert spindle design system strategy which is based on the efficient utilization of past design experience, the laws of machine design, dynamics and metal cutting mechanics. The configuration of the spindle is decided from the specifications of the workpiece material, desired cutting conditions, and most common tools used on the machine tool. The spindle drive mechanism, drive motor, bearing types, and spindle shaft dimensions are selected based on the target applications. The paper provides a set of fuzzy design rules, which lead to an interactive and automatic design of spindle drive configurations. The structural dynamics of the spindle are automatically optimized by distributing the bearings along the spindle shaft. The proposed strategy is to iteratively predict the Frequency Response Function (FRF) of the spindle at the tool tip using the Finite Element Method (FEM) based on the Timoshenko beam theory. The predicted FRF of the spindle is integrated to the chatter vibration stability law, which indicates whether the design would lead to chatter vibration free cutting operation at the desired speed and depth of cut for different flutes of cutters. The arrangement of bearings is optimized using the Sequential Quadratic Programming (SQP) method. 相似文献
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Virtual Design and Optimization of Machine Tool Spindles 总被引:4,自引:0,他引:4
An integrated digital model of spindle, tool holder, tool and cutting process is presented. The spindle is modeled using an in-house developed Finite Element system. The preload on the bearings and the influence of gyroscopic and centrifugal forces from all rotating parts due to speed are considered. The bearing stiffness, mode shapes, Frequency Response Function at any point on the spindle can be predicted. The static and dynamic deflections along the spindle shaft as well as contact forces on the bearings can be predicted with simulated cutting forces before physically building and testing the spindles. The spacing of the bearings are optimized to achieve either maximum dynamics stiffness or maximum chatter free depth of cut at the desired speed region for a given cutter geometry and work-piece material. It is possible to add constraints to model mounting of the spindle on the machine tool, as well as defining local springs and damping elements at any nodal point on the spindle. The model is verified experimentally. 相似文献
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M. Matsubara H. Rahnejat R. Gohar 《International Journal of Machine Tools and Manufacture》1988,28(4):429-442
This paper outlines a method for the modelling of a precision spindle supported by ball bearings. The support bearings are represented as piece-wise linear springs with damping provided by concentrated forces external to the bearings at each end of the spindle. The simplified damping model can simulate the squeeze film effect exerted by seals. The main elastic modes of the spindle vibrations are considered and the results corresponding to various machine tool spindle designs under various operating conditions are presented. 相似文献
20.
微型钻头磨床砂轮轴振动严重地影响了钻头加工精度。通过对砂轮轴的传递矩阵建模分析,发现砂轮轴轴承刚工和砂轮尺寸是影响其振动的固有频率与振型的两个主要因素。轴承刚度越高,砂轮尺寸越小,基各阶固有频率越高;由于砂轮小对称布置,砂轮尺寸越大,各阶振型的振幅也越大。在调整砂轮轴轴承预紧前,采用Machinery Analyzer model 2130振动分析仪的测试结果也显示该砂轮轴在低频部分的振动较为严重,预紧轴承和精修砂轮后,振动消除。 相似文献