A detachable design method of large-sized structure for heavy duty machine tool based on joint surface dynamics characteristic analysis

Ball screw mechanisms (BSMs) are used as accuracy transmission components in a wide range of industries and are characterized by their high accuracy. More specifically, the positioning accuracy of BSM has a significant effect on the accuracy of machine tool. Based on the macro-micro multiscale method, an exponential prediction model for the BSM positioning accuracy was developed considering time-varying working conditions (load and rotational speed) and feed modes. Since the accuracy degradation is mainly caused by wear, a microscopic approach was proposed to describe the positioning accuracy retention and the microscopic wear process was investigated. The sliding contact of the asperities between the ball and raceway was analyzed, and the microscopic wear behavior of the asperities was determined. Considering the time-varying working conditions, the BSM positioning accuracy characteristics were obtained under the normal feed mode by conducting suitable tests. The exponential wear model used the wear index to describe the wear status based on the positioning accuracy measurement. The accuracy loss value and the prediction index of positioning accuracy were determined based on an exponential model, and the effective lifetime of the BSM was predicted. Finally, the exponential prediction model was used in negative/positive skew feed distribution, and the effective lifetime determined.

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“…where σ e represents the normal elastic deformation of a single asperity and can be written as following 25 :…”

Section: Microscopic Wear Of Contact Asperitymentioning

confidence: 99%

Positioning accuracy degradation and lifetime prediction of the ball screw considering time-varying working conditions and feed modes

Cheng

Liu

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…Then, the contact force can be obtained by integrating the asperity results using the size distribution function. The MB model has been widely used to analyze the contact effect of various structures 20,21 . Liao et al 22 combined the MB model with the virtual material method to analyze the contact effect of bolted joints in machine tools, where only the elastic asperities and plastic asperities at the joint interface were involved, and the elastic–plastic asperities were not considered.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Modeling of Tie-bolt Rotors via Fractal Contact Theory and Virtual Material Method

Qin

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part C:

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Tie-bolt rotors, comprised of multiple stages of discs fastened by tie bolts, are commonly used in heavy-duty gas turbines. The contact interfaces between adjacent discs have considerable influence on the dynamic characteristics of tie-bolt rotors. Although many studies on the modeling of tie-bolt rotors have been reported, it is still a challenge to develop a relatively simple, efficient, and accurate model for such a kind of complex rotors. In this article, a new virtual material modeling method is proposed to analyze the dynamic characteristics of tie-bolt rotors. The elastic modulus and Poisson ratio of the virtual material are determined from the interface contact stiffness, which is derived based on the three-dimensional fractal contact theory. To verify the modeling approach proposed here, modal tests are conducted on a tie-bolt rotor specimen, of which the measured natural frequencies are compared with the simulation results. Finally, by using the verified modeling approach, the dynamic behaviors of tie-bolt rotors are investigated comprehensively, where the effects of fractal dimension parameters and preload level on rotor dynamics are evaluated.

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A detachable design method of large-sized structure for heavy duty machine tool based on joint surface dynamics characteristic analysis

Cited by 2 publications

References 26 publications

Positioning accuracy degradation and lifetime prediction of the ball screw considering time-varying working conditions and feed modes

Positioning accuracy degradation and lifetime prediction of the ball screw considering time-varying working conditions and feed modes

Dynamic Modeling of Tie-bolt Rotors via Fractal Contact Theory and Virtual Material Method

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