Modal Testing for Heavy Machine Tool Using Active Excitation

2014 ◽  
Vol 536-537 ◽  
pp. 1326-1332 ◽  
Author(s):  
Bo Luo ◽  
Bin Li ◽  
Xin Yong Mao ◽  
Hui Cai
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Inertial Force ◽  
Modal Testing ◽  
Modal Parameters ◽  
Part Quality ◽  
Machine Tool Structure ◽  
Machining Speed ◽  
Heavy Machine ◽  
Large Machine

For application in large machine tools, the machined part quality, accuracy as well as machining speed depende greatly on the dynamics of the structure. In this paper, an active-excitation modal analysis (AEMA), using inertial force of the moving slider to excite the structural modes, is proposed. Modal parameters of the machine tool structure estimated by AEMA are experimentally validated. Since the artificial excitation produced by elaborate excitation equipment is replaced by the inertial force of the slider, the proposed method is much more practical and economical than traditional methods.

Use of Shock Compared With Harmonic Excitation in Machine Tool Structure Analysis

1974 ◽  
Vol 96 (1) ◽  
pp. 187-195 ◽  
Author(s):  
J. Tlusty ◽  
K. C. Lau ◽  
K. Parthiban
Keyword(s):  
Machine Tool ◽  
Structure Analysis ◽  
Machine Tools ◽  
Harmonic Excitation ◽  
Mode Shapes ◽  
Shock Excitation ◽  
Machine Tool Structure ◽  
Degree Of Stability ◽  
The Individual

The paper recapitulates the method of analyzing stability against chatter of machine tools as it has been practised by one of the authors for many years. Several new features of the method are presented and, mainly, comments are given on the use of shock excitation for determining both the receptances of the structure and its mode shapes. The method itself consists of comparing results of cutting tests and of excitation tests for various directional orientations of the cut in the structure and of identifying the contribution of the individual modes to the resulting degree of stability.

An investigation on modeling and compensation of synthetic geometric errors on large machine tools based on moving least squares method

2016 ◽  
Vol 232 (3) ◽  
pp. 412-427 ◽  
Author(s):  
Zihan Li ◽  
Wenlong Feng ◽  
Jianguo Yang ◽  
Yiqiao Huang
Keyword(s):  
Machine Tool ◽  
Least Squares ◽  
Error Compensation ◽  
Machine Tools ◽  
Geometric Error ◽  
Moving Least Squares ◽  
Geometric Errors ◽  
Position Accuracy ◽  
Type Machine ◽  
Large Machine

This article intends to provide an efficient modeling and compensation method for the synthetic geometric errors of large machine tools. Analytical and experimental examinations were carried out on a large gantry-type machine tool to study the spatial geometric error distribution within the machine workspace. The result shows that the position accuracy of the tool-tip is affected by all the translational axes synchronously, and the position error curve shape is non-linear and irregular. Moreover, the angular error combined with Abbe’s offset during the motion of a translational axis would cause Abbe’s error and generate significant influence on the spatial positioning accuracy. In order to identify the combined effect of the individual error component on the tool-tip position accuracy, a synthetic geometric error model is established for the gantry-type machine tool. Also, an automatic modeling algorithm is proposed to approximate the geometric error parameters based on moving least squares in combination with Chebyshev polynomials, and it could approximate the irregular geometric error curves with high-order continuity and consistency with a low-order basis function. Then, to implement real-time error compensation on large machine tools, an intelligent compensation system is developed based on the fast Ethernet data interaction technique and external machine origin shift, and experiment validations on the gantry-type machine tool showed that the position accuracy could be improved by 90% and the machining precision could be improved by 85% after error compensation.

scholarly journals Analysis of Dynamic Characteristics for Machine Tools Based on Dynamic Stiffness Sensitivity

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2260
Author(s):  
Chunhui Li ◽  
Zhiqiang Song ◽  
Xianghua Huang ◽  
Hui Zhao ◽  
Xuchu Jiang ◽  
...  
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Dynamic Stiffness ◽  
Variable Stiffness ◽  
Structural Vibration ◽  
Dynamic Experiment ◽  
Machine Tool Structure ◽  
Analysis Experiment ◽  
Five Axis

Dynamic parameters are the intermediate information of the entirety of machine dynamics. The differences between components have not been combined with the structural vibration in the cutting process, so it is difficult to directly represent the dynamic characteristics of the whole machine related to spatial position. This paper presents a method to identify sensitive parts according to the dynamic stiffness-sensitivity algorithm, which represents the dynamic characteristics of the whole machine tool. In this study, two experiments were carried out, the simulation verification experiment (dynamic experiment with variable stiffness) and modal analysis experiment (vibration test of five-axis gantry milling machine). The key modes of sensitive parts obtained by this method can represent the position-related dynamic characteristics of the whole machine. The characteristic obtained is that the inherent properties of machine-tool structure are independent of excitation. The method proposed in this paper can accurately represent the dynamic characteristics of the whole machine tool.

scholarly journals A new modal analysis method applied to changing machine tool using clustering

2020 ◽  
Vol 12 (10) ◽  
pp. 168781402096832
Author(s):  
Xuchu Jiang ◽  
Xinyong Mao ◽  
Yingjie Chen ◽  
Caihua Hao
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Natural Frequency ◽  
Efficient Method ◽  
Machine Tools ◽  
Vibration Signal ◽  
Modal Parameters ◽  
Analysis Method ◽  
Modal Parameter ◽  
The Difference

The states of the machine tool, such as the components’ position and the spindle speed, play leading roles in the change of dynamic parameters. However, the traditional modal analysis method that modal parameters manually identified from vibration signal is greatly interfered by harmonics, and the process of eliminating interference is very inefficient and subjective. At present, there is a lack of a standard and efficient method to characterize modal parameter changes in different states of machine tools. This paper proposes a new machine tool modal classification analysis method based on clustering. The characteristics related to the modal parameters are extracted from the response signal in different states, and the clustering results are used to reflect the changes of machine tool modal parameters. After the amplitude of the frequency response function is normalized, the characteristics related to the natural frequency are acquired, and the clustering results further reflect the difference of the natural frequency of the signal. The new method based on clustering can be a standard and efficient method to characterize modal parameter changes in different states of machine tools.

An Analysis and Modeling of the Dynamic Stability of the Cutting Process Against Self-Excited Vibration

2020 ◽  
Vol 22 (4) ◽  
pp. 1287-1300
Author(s):  
A. Motallebia ◽  
A. Doniavi ◽  
Y. Sahebi
Keyword(s):  
Machine Tool ◽  
Removal Rate ◽  
Dimensional Accuracy ◽  
Modal Testing ◽  
Cutting Process ◽  
Work Piece ◽  
Stability Diagrams ◽  
Machine Tool Structure ◽  
Excited Vibration ◽  
The Stability

AbstractChatter is a self-excited vibration which depends on several parameters such as the dynamic characteristics of the machine tool structure, the material of the work piece, the material removal rate, and the geometry of tools. Chatter has an undesirable effect on dimensional accuracy, smoothness of the work piece surface, and the lifetime of tools and the machine tool. Thus, it is useful to understand this phenomenon in order to improve the economic aspect of machining. In the present article, first the theoretical study and mathematical modeling of chatter in the cutting process were carried out, and then by performing modal testing on a milling machine and drawing chatter stability diagrams, we determined the stability regions of the machine tool operation and recognized that witch parameter has a most important effect on chatter.

Dynamic Characteristics Analysis of Gantry Machining Center Structure

2013 ◽  
Vol 819 ◽  
pp. 24-28
Author(s):  
Yan Yun Tang ◽  
Ze Yu Weng ◽  
Li Ka Fang ◽  
Xiang Gao ◽  
Jian De Hu ◽  
...  
Keyword(s):  
Machine Tool ◽  
Machine Tools ◽  
Weak Link ◽  
Dynamic Performance ◽  
Modal Parameters ◽  
Machining Center ◽  
Characteristics Analysis ◽  
Relative Excitation ◽  
Dynamic Characteristics Analysis ◽  
Modern Machine

The dynamic performance of modern machine tools is more and more highly emphasized. The research purpose of this paper is to research dynamic performance of gantry machining center through modal experiment. In this paper, the theory of relative excitation test on the machine tool is expounded, and relative excitation test is carried on gantry machining center and then the modal parameters of this machine tool are obtained through experimental modal analysis. Analyze the weak link of this gantry machining center, show that the stiffness of Z direction of Z to feed component of this machine tool is insufficient and the stiffness of X, Y direction of ram is insufficient.

Modeling and simulation of the interaction of manufacturing process and machine tool structure in flycutting machining

2014 ◽  
Vol 229 (15) ◽  
pp. 2730-2736 ◽  
Author(s):  
Wanqun Chen ◽  
Yazhou Sun ◽  
Chenhui An ◽  
Hao Su ◽  
Kai Yang ◽  
...  
Keyword(s):  
Machine Tool ◽  
Dynamic Performance ◽  
Great Influence ◽  
Machining Process ◽  
State Space Method ◽  
Machined Surface ◽  
Machine Tool Structure ◽  
Machining Speed ◽  
The Relationship ◽  
Space Method

The process machine interactions in the flycutting machining are presented by integrating the state-space method and finite element method. The prediction of the cutting force fluctuations in the machining process caused by the compliance of machine tool structure is achieved. Furthermore, the relationship between the dynamic performance of the machine tool structure and the machining speed is discussed, which has great influence on the root mean square of waviness and flatness on the machined surface. The simulation results are validated by experiments.

scholarly journals Dynamic Modeling and Experimental Research on Position-dependent Behavior of Twin Ball Screw Feed System

2021 ◽  
Author(s):  
Meng Duan ◽  
Hong Lu ◽  
Xinbao Zhang ◽  
Zhangjie Li ◽  
Yongquan Zhang ◽  
...  
Keyword(s):  
Machine Tool ◽  
Dynamic Model ◽  
Machine Tools ◽  
Experimental Tests ◽  
Ball Screw ◽  
Fe Model ◽  
Feed System ◽  
Dependent Behavior ◽  
Machine Tool Structure ◽  
Important Means

Abstract To establish the dynamic model of machine tool structure is an important means to assess the performance of the machine tool structure during the cutting process. It’s necessary to study the dynamics of the machine tools in different configurations for the sake of analyzing the dynamic behavior of the machine tools in the entire workspace. In this paper, a robust approach is presented to build an efficient and reliable dynamic model to evaluate the position-dependent dynamics of the twin ball screw (TBS) feed system. First, the TBS feed system is divided into several components and a finite element (FE) model is built for each component. Second, the Craig-Bampton method is proposed to reduce the order of the substructures. Third, a multipoint constraints (MPCs) method was introduced to model the mechanical joints substructures of the TBS system, and the spring-damper element (SDE) is employed to connect the condensation nodes. Finally, a series experimental tests and full order FE analysis are conducted on the self-designed TBS worktable in the four positions to validate the effectiveness of the proposed dynamic model. The results show that the proposed approach evaluates accurately the position-dependent behavior of the TBS system.

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