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Shi Y.,Tianjin University | Zhao X.,Tianjin University | Zhang H.,Tianjin University | Zhang H.,Tianjin Polytechnic University | And 2 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2015

This work describes a new top-down design method for the stiffness of precision machine tools that considers the entire machine stiffness to guarantee the stiffness requirements in the initial design stage. A stiffness modelling method and a stiffness matching design method are presented to achieve the top-down design of the stiffness. A new stiffness characterisation using the stiffness coefficients for characterising the stiffness of the structural parts and the functional units is proposed. The deformation model of the entire machine is established based on multi-body system theory, and the equations of the stiffness coefficients for the deformations of the components are established based on the simultaneous equations of the static equilibrium equations, the deformation compatibility equations and the physical equations. The three-direction (3D) stiffness model is obtained by substituting the equations into the deformation model that reflects the stiffness characteristics of the machine tool. Thus, the reliability of the stiffness model is verified by experiments. Next, the stiffness matching design is performed to confirm the reasonable stiffness values of the parts based on the stiffness model. The finite element method (FEM) is used to validate the proposed method. The contribution rate of the stiffness of the parts to the stiffness of the entire machine is analysed. © 2015 Springer-Verlag London


PubMed | Beijing Machine Tool Research Institute and Tianjin University
Type: Journal Article | Journal: The Review of scientific instruments | Year: 2017

The rotational accuracy of a machine tool spindle has critical influence upon the geometric shape and surface roughness of finished workpiece. The rotational performance of the rolling element bearings is a main factor which affects the spindle accuracy, especially in the ultra-precision machining. In this paper, a new method is developed to measure the rotational accuracy of rolling element bearings of machine tool spindles. Variable and measurable axial preload is applied to seat the rolling elements in the bearing races, which is used to simulate the operating conditions. A high-precision (radial error is less than 300 nm) and high-stiffness (radial stiffness is 600 N/m) hydrostatic reference spindle is adopted to rotate the inner race of the test bearing. To prevent the outer race from rotating, a 2-degrees of freedom flexure hinge mechanism (2-DOF FHM) is designed. Correction factors by using stiffness analysis are adopted to eliminate the influences of 2-DOF FHM in the radial direction. Two capacitive displacement sensors with nano-resolution (the highest resolution is 9 nm) are used to measure the radial error motion of the rolling element bearing, without separating the profile error as the traditional rotational accuracy metrology of the spindle. Finally, experimental measurements are performed at different spindle speeds (100-4000 rpm) and axial preloads (75-780 N). Synchronous and asynchronous error motion values are evaluated to demonstrate the feasibility and repeatability of the developed method and instrument.


Fan W.,Beijing Information Science and Technology University | Wang K.,Beijing Information Science and Technology University | Zha C.,Beijing Machine Tool Research Institute
Jinshu Rechuli/Heat Treatment of Metals | Year: 2014

Hot working process of GCr15 steel ball screw is introduced, including preheating treatment, high-temperature aging, surface heat treatment, cryogenic treatment, stabilization treatment and so on. Good comprehensive properties of ball screw can be obtained by reasonably controlling process parameters of all the stages.


Daxian H.,Beijing Information Science and Technology University | Keshe W.,Beijing Information Science and Technology University | Chuliang Z.,Beijing Machine Tool Research Institute | Yong Z.,Beijing Information Science and Technology University | Haifeng Y.,Beijing Information Science and Technology University
Applied Mechanics and Materials | Year: 2013

Ball screw feeding system is a very important part of the machine tool. The ball screw of High-speed at the same time bring the vibration, noise, temperature rise due to friction and many problems. Noise and temperature rise are the key factors constrain the ball screw in the High-speed. The article summarized the ball screw causes of the vibration, noise, comprehensive both at home and abroad research results to the ball screw vibration and noise generating mechanism.Then pointed out that the ball screw noise generation is the main reason of the screw groove waveness arouses nut forced vibration.Introduced the latest progress of the ball screw drive system modeling and the vibration model analysis,specific introduces several methods of reducing vibration and noise reduction. And talk about the development trend of ball screw vibration and noise to the future. © (2013) Trans Tech Publications, Switzerland.


Huang L.L.,Beijing Information Science and Technology University | Wang K.S.,Beijing Information Science and Technology University | Zha C.L.,Beijing Machine Tool Research Institute
Applied Mechanics and Materials | Year: 2014

The accuracy reliability problems have long been studied. In order to research ball screw’s accuracy reliability under radical force, some work have done. By using mechanical vibration theory, the dynamic response equation of the beams under external excitation has been derived out. Then by using Matlab, the dynamic response of screw rod under working circumstance is studied, and the dynamic response equation is obtained. At last some calculation examples have given. Results showed that screw’s polar moment of inertia section errors have decisive influences on precision and reliability. By using vibration theory and second moment theory, a new meathod have been proposed in evaluating the ball screw accuracy reliability. © (2014) Trans Tech Publications, Switzerland.


Zhang Y.,Jiangsu University of Science and Technology | Wei H.,Jiangsu University of Science and Technology | Wu Z.,Beijing Machine Tool Research Institute
Journal of Information and Computational Science | Year: 2013

A Least Squares Support Vector Machines (LSSVM) combined inverse control strategy is proposed for two-motor variable frequency speed-regulating system. First, a right inverse control method is adopted to decouple speed and tension of the two-motor system. Then, a left inverse soft-sensing model is applied to estimate the motor rotor flux, which is substituted into the right inverse system in order to form a whole combined inverse controller. To overcome the difficulties in implementing the combined inverse controller by an analytical method, a LSSVM is used to approximate the static nonlinear mapping. Designed two additional controllers, the LSSVM combined inverse control strategy is achieved. Finally, the effectiveness and capability of this proposed control strategy is verified by computer simulations. Copyright © 2013 Binary Information Press.

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