Analysis on Dynamic Characteristics of CNC Machine Tool and Experiment with Influence of Rolling Guide Joint Considered

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.

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.


2012 ◽  
Vol 605-607 ◽  
pp. 1519-1522
Author(s):  
Lei Sun ◽  
Xia Wang

The modal analysis and harmonic response analysis of milling head box were done by means of finite element method. Find out its characteristics of vibration modal. The analysis is conducive to the design of the milling head box of machine tool. It makes a base for optimized design and remanufacturing.


2011 ◽  
Vol 52-54 ◽  
pp. 989-994
Author(s):  
Xiao Peng Li ◽  
Wei Nie ◽  
Bang Chun Wen

Linear rolling guide is one of the most essential parts of the NC modern machine tools, and they play a significant supporting and guiding role in machine tools components. Especially, the joint surface between guides has great influence on machine's dynamic characteristics. According to this, in this work, taken the Japanese THK Corporation's SNS35LR rolling guide as specific study object, the finite element model of guide pair has been established with the joint surface influence considered. And by the method of the theoretical analysis with the experimental confirmation combined; the dynamic characteristics of the linear rolling guide pair's were studied relatively. Thus, the theoretical model and the finite element model established in this paper can be confirmed by the experiment. It has been found that the theoretical models established are consistent with the results of experiment. This study results can provide useful guidance for the dynamic analysis and the structure optimization of CNC machine tools, and numerical simulation in engineering and design in the development of such machines with rolling guide used.


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.


2011 ◽  
Vol 361-363 ◽  
pp. 1553-1556
Author(s):  
Lei Sun ◽  
Ming Hai Wang ◽  
Xiao Peng Li ◽  
Yue Sun

Taking moving trestle of machine tool as example,the modal analysis and harmonic response analysis were done by means of finite element method. Find out its characteristics of vibration modal. The analysis is conducive to the design of the moving trestle of machine tool. It makes a base for optimized design and remanufacturing.


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.


2011 ◽  
Vol 480-481 ◽  
pp. 1496-1501
Author(s):  
Liu Hui

In order to study the dynamic characteristics of a super-long-span cable-stayed bridge which is semi-floating system, the spatial finite element model of this cable-stayed bridge was established in ANSYS based on the finite element theory.Modal solution was conducted using subspace iteration method, and natural frequencies and vibration modes were obtained.The dynamic characteristics of this super-long-span cable-stayed bridge were then analyzed.Results showed that the super-long-span cable-stayed bridge of semi-floating system has long basic cycle, low natural frequencies, dense modes and intercoupling vibration modes.


Author(s):  
Youngin Choi ◽  
Seungho Lim ◽  
Kyoung-Su Park ◽  
No-Cheol Park ◽  
Young-Pil Park ◽  
...  

The System-integrated Modular Advanced ReacTor (SMART) developed by KAERI includes components like a core, steam generators, coolant pumps, and a pressurizer inside the reactor vessel. Though the integrated structure improves the safety of the reactor, it can be excited by an earthquake and pump pulsations. It is important to identify dynamic characteristics of the reactor internals considering fluid-structure interaction caused by inner coolant for preventing damage from the excitations. Thus, the finite element model is constructed to identify dynamic characteristics and natural frequencies and mode shapes are extracted from this finite element model.


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.


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