The Analysis on Dynamic Characteristics and the Structural Optimization of HRG Polishing Machine Tool

2013 ◽  
Vol 770 ◽  
pp. 54-58 ◽  
Author(s):  
Ming Jun Chen ◽  
Lin Yu ◽  
He Nan Liu ◽  
Wan Qun Chen

The dynamic characteristics of machine tool directly affect machining accuracy of the final parts. Taking the self-developed HRG ultra-precision polishing CNC machine tool as the research object, the simplified finite element model is established with the finite element analysis software to do the dynamic analysis and the natural frequency is detected as the index of the dynamic performances. Based on the comparative analysis of the natural frequency and vibration modes, the gantry and the supporting frame are recognized as structural weaknesses of the machine tool, and then the modal test is done to verify simulation results. Eventually the structural weaknesses are optimized effectively. The 1st order nature frequency of the optimized gantry and the optimized supporting frame is increased 75.5% and 80.8% respectively so that they have better dynamic performances, resulting in offering higher workpiece quality and process stability.

Author(s):  
Prabhu Raja Venugopal ◽  
M Kalayarasan ◽  
PR Thyla ◽  
PV Mohanram ◽  
Mahendrakumar Nataraj ◽  
...  

Higher damping with higher static stiffness is essential for improving the static and dynamic characteristics of machine tool structures. The structural vibration in conventional machine tools, which are generally made up of cast iron and cast steel, may lead to poor surface finish and the dimensional inaccuracy in the machined products. It leads to the investigation of alternative machine tool structural materials such as concrete, polymer concrete, and epoxy granite. Although epoxy granite has a better damping capacity, its structural stiffness (Young's modulus) is one-third as compared to cast iron. Therefore, the present work represents optimization of the structural design of the vertical machining center column by introducing various designs of steel reinforcement in the epoxy granite structure to improve its static and dynamic characteristics using experimental and numerical approaches. A finite element model of the existing cast iron vertical machining center column has been developed and validated against the experimental data obtained using modal analysis. Furthermore, finite element models for various epoxy granite column designs have been developed and compared with the static and dynamic characteristics of cast iron column. A total of nine design configurations for epoxy granite column with steel reinforcement are evolved and numerical investigations are carried out by finite element analysis. The proposed final configuration with standard steel sections has been modeled using finite element analysis for an equivalent static stiffness and natural frequencies of about 12–20% higher than cast iron structure. Therefore, the proposed finite element model of epoxy-granite-made vertical machining center column can be used as a viable alternative for the existing column in order to achieve higher structural damping, equivalent or higher static stiffness and, easy and environmental-friendly manufacturing process.


Author(s):  
Shanmugam Chinnuraj ◽  
PR Thyla ◽  
S Elango ◽  
Prabhu Raja Venugopal ◽  
PV Mohanram ◽  
...  

Machine tools are used to manufacture components with desired size, shape, and surface finish. The accuracy of machining is influenced by stiffness, structural damping, and long-term dimensional stability of the machine tool structures. Components machined using such machines exhibit more dimensional variations because of the excessive vibration during machining at higher speeds. Compared to conventional materials like cast iron, stone-based polymer composites such as epoxy granite have been found to provide improved damping characteristics, by seven to ten folds, due to which they are being considered for machine tool structures as alternate materials. The stiffness of structures made of epoxy granite can be enhanced by reinforcing with structural steel. The current work highlights the design and analysis of different steel reinforcements in the lathe bed made of the epoxy granite composite to achieve equivalent stiffness to that of cast iron bed for improved static and dynamic performances of the CNC lathe. A finite element model of the existing the cast iron bed was developed to evaluate the static (torsional rigidity) and dynamic characteristics (natural frequency) and the results were validated using the experimental results. Then finite element models of five different steel reinforcement designs of the epoxy granite bed were developed, and their static and dynamic behaviors were compared with the cast iron bed through numerical simulation using finite element analysis. The proposed design (Design-5) of the epoxy granite bed is found to have an improvement in dynamic characteristics by 4–10% with improved stiffness and offers a mass reduction of 22% compared to the cast iron bed, hence it can be used for the manufacture of the CNC lathe bed and other machine tool structures for enhanced performance.


2012 ◽  
Vol 443-444 ◽  
pp. 745-750 ◽  
Author(s):  
Xiao Peng Li ◽  
Hui Fan Nie

The 3D finite element model of CAKxxx CNC machine tool is established and the static/dynamic characteristics of the machine tool are analyzed with finite element method when the influence of the linear rolling guide (LRG) joint is considered or neglected. The lowest five natural frequencies and vibration modal shapes are obtained in both cases. It shows that when considering the influence of the LRG joint, each of the lowest five natural frequencies is 14 Hz smaller than the results of neglecting the influence, and the vibration modal shapes are more stable. The modal experiment shows that the results of considering the influence of the LRG joint are closer to the actual situation. It also proves that LRG joint has great influence on the dynamic characteristic of the machine tool. It provides an important reference for accurate modeling and dynamic design of machine tool.


2012 ◽  
Vol 507 ◽  
pp. 217-221 ◽  
Author(s):  
Zhong Qi Sheng ◽  
Sheng Li Dai ◽  
Yu Chang Liu ◽  
Hua Tao Fan

Relying on HTC3250µn and HTC2550hs high-speed precision CNC turning center, this paper analyzes the static and dynamic characteristics of CNC machine tool spindle with finite element analysis software. Based on the results and using ANSYS software, this paper considers the volume and amplitude of vibration model as the objective function to optimize the size of the spindle. According to the optimized size of spindle, this paper analyzes the static and dynamic characteristics of the CNC machine tool spindle again and concludes the optimization results.


2014 ◽  
Vol 543-547 ◽  
pp. 76-79
Author(s):  
Ting Ting Guo ◽  
Teng Jiao Sun ◽  
Fang Shao

Taking a grinding machine tool as an example, this paper obtained the static stiffness of the machine tool by finite element analysis method. The structure and technical parameters of the machine tool were introduced at first.Then, the finite element model of the machine tool was established. The static stiffness of the machine tool in x-, y-, and z-directions were simulated at last. The results show that, the static stiffness in x-direction is 2.0062×107 N/m, the static stiffness in y-direction is 0.821×107 N/m, and the static stiffness in z-direction is 0.2992×107 N/m. This paper provides advices for structure optimization of the machine tool which is convenient for improving the machining accuracy.


2013 ◽  
Vol 281 ◽  
pp. 165-169 ◽  
Author(s):  
Xiang Lei Zhang ◽  
Bin Yao ◽  
Wen Chang Zhao ◽  
Ou Yang Kun ◽  
Bo Shi Yao

Establish the finite element model for high precision grinding machine which takes joint surface into consideration and then carrys out the static and dynamic analysis of the grinder. After the static analysis, modal analysis and harmonic response analysis, the displacement deformation, stress, natural frequency and vibration mode could be found, which also helps find the weak links out. The improvement scheme which aims to increase the stiffness and precision of the whole machine has proposed to efficiently optimize the grinder. And the first natural frequency of the optimized grinder has increased by 68.19%.


2014 ◽  
Vol 555 ◽  
pp. 555-560 ◽  
Author(s):  
Doru Bardac ◽  
Constantin Dogariu

This paper presents a method to investigate the characteristics of a turning high-speed spindle system. The geometric quality of high-precision parts is highly dependent on the performance of the entire machining system,especially by the main spindle behaviour. The machine tool main spindle units is focused on direct driven spindle units for high-speed and high performance cutting. This paper analyzes the static behavior for a turning machine spindle and presents some activities to improve the CAD model for such complex systems. The proposed models take into account the spindle with the detailed bearing system. The analysis was performed during the design activity and was based on Finite Elements Method. Starting from the 3D designed model, using FEM done by means of ANSYS analysis the structure stiffness was evaluated and, by consequence, the influence on the machine tool precision. The aim of this paper is to develop a finite element model of the machine spindle system and to use this method for design optimization. The 3D model was designed using the SolidWorks CAD software. The static analysis was completed by modal, harmonic response and thermal analysis, but their results will be presented in other papers.


2009 ◽  
Vol 16-19 ◽  
pp. 510-514 ◽  
Author(s):  
Yao Man Zhang ◽  
Zhi Kun Xie ◽  
Yong Xian Liu

The linear rolling guideway is one of the most essential parts of the machine tool. So it is very important to analyze the dynamic-static characteristic of the machine tool consider rolling guideway and to study the effect on machinery function. The paper’s research is based on a NC machine tool produced by a certain plant of machine tools. Methods of simulating the rolling guideway support are studied, and the configuration of the spring damper elements of the bearing supports are also studied, and the finite element analysis on the CKS6125 machine tool has been made to confirm its dynamic characteristics. Then the finite element analysis models are validated by some experiments.


2013 ◽  
Vol 712-715 ◽  
pp. 1391-1394
Author(s):  
Zhi Li ◽  
X. S. Zhao ◽  
D. W. Zhang

Modal analysis is one way of studying the dynamic characteristics of the mechanical. In order to study the dynamic characteristics of machine tool,numerical machine model is set up with finite element analysis software,of which validity is verified by experimental modal analysis.The experimental test also provide the boundary conditions, so as to further structure modification and dynamic characteristic design


2011 ◽  
Vol 80-81 ◽  
pp. 1051-1054
Author(s):  
Chun Xia Zhu ◽  
Bin Li ◽  
Ji Man Luo

In order to analyze accurately the dynamic characteristics of guideway joints of CNC, the finite element model(FEM) of guideway joints of CNC is built in ANASYS software, which that springs and damping units imitate guideway joints in this paper. The proposed method can predict the regular pattern which joint stiffness and joint span affect natural frequency and harmonic response. The research demonstrates that the method predicts well the dynamic characteristics of the guideway joints of CNC; therefore, it can be a reference for dynamic optimization design of guideway joints of CNC machine tool.


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