New Approaches to the Modal Analysis for Machine Tool Structure

1984 ◽  
Vol 106 (1) ◽  
pp. 40-47 ◽  
Author(s):  
Shinyi Wang ◽  
Hisayoshi Sato ◽  
Masanori O-Hori
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Impulse Response ◽  
Degrees Of Freedom ◽  
Computation Time ◽  
Measured Data ◽  
Sufficient Accuracy ◽  
New Approaches ◽  
Curve Fit ◽  
Machine Tool Structure

Three new approaches to modal analysis using impulse response were developed to identify the vibration characteristics of machine tool structure. The methods are based on the principle of minimizing the sum of squares of the differences between the measured data and the analytical expression. One of the methods successfully simplified the algorithm of the curve fit procedure and the computation time was significantly economized, so that it could be carried out by a microcomputer with sufficient accuracy for the system having about 30-degrees-of-freedom.

Application of Operational Modal Analysis to a Machine Tool Testing

2004 ◽  
Author(s):  
Emmanuil Kushnir
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Random Processes ◽  
Operating Conditions ◽  
Frequency Range ◽  
Mechanical Structure ◽  
Machine Tool Structure ◽  
Exciting Forces ◽  
Stationary Random Processes

Modal analysis testing of a mechanical structure is performed usually by artificial excitation of a structure and measuring input forces and output responses of a mechanical system. The excitation is either transient (impact hammer testing), random, burst-random or sinusoidal (shaker testing). The modern signal processing tools enable to determine properties of a mechanical structure such as resonance frequencies, damping ratios, and mode patterns by measuring the response of the structure without using an artificial excitation. The advantage of this technique is that modal parameters of a structure may be evaluated while the structure is under actual operating conditions. That will allow developing a model within true boundary conditions and actual force and vibration levels. The machine tool structure characteristics that effect productivity and quality have to be evaluated by testing. These characteristics include natural frequencies, modes of vibration, and external sources of high level vibration. Not all modes of machine tool structure effect machine quality. As a result only the modes that are excited during cutting have to be taken in the account. This approach narrowed the frequency range, which has to be considered in test. The machine tool during cutting and/or idling is loaded by a set of external and internal exciting forces. Spectrum, frequency range and application points of these forces are unknown in many cases. Under these exciting forces the vibration between the tool and workpiece, and vibration of machine tool components are sums of many independent vibrations and may be considered as stationary random processes. This assumption allows applying the theory of stationary random processes to machine tool dynamic testing during cutting. Several characteristics of random processes are used to separate harmonic vibration from narrow-band random vibration at natural frequencies. The spectral analysis of machined surface profiles and its correlation with observed vibration allows choosing modes that have to be developed. The analysis of these modes provides a basis for machine tool structure improvement. The proposed experimental approach was verified by experiments at different machine tools. Results of these tests are presented in the paper.

Experimental Complex Modal Analysis of Machine Tool Structures

1989 ◽  
Vol 111 (2) ◽  
pp. 116-124 ◽  
Author(s):  
Y. C. Shin ◽  
K. F. Eman ◽  
S. M. Wu
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Mode Analysis ◽  
Mode Shapes ◽  
Coupled Modes ◽  
Complex Mode ◽  
Machine Tool Structure ◽  
Experimental Complex ◽  
Complex Modal Analysis ◽  
Complex Modal

Despite the well-established theories and considerable experimental research, the identification of the complex mode shapes of a real machine tool structure with general damping still remains a formidable task. Moreover, the existence of closely coupled modes with heavy damping introduces additional difficulties. This paper presents a detailed procedure for experimental complex modal analysis of a machine tool structure by the Dynamic Data System method. The accuracy and efficiency are first illustrated by numerical examples through simulation studies. It has been shown that closely coupled modes and modes with heavy damping can be successfully identified from both simulated and actual experimental data from a machine tool. Complex mode shapes were also obtained without adding any complexity or losing accuracy as compared to normal mode analysis. The experimental results obtained by the proposed method were compared with those based on the FFT algorithm.

High-speed test of thermal effects for a machine-tool structure based on modal analysis

1986 ◽  
Vol 8 (2) ◽  
pp. 72-78 ◽  
Author(s):  
M. Matsuo ◽  
T. Yasui ◽  
T. Inamura ◽  
M. Matsumura
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Thermal Effects ◽  
High Speed ◽  
Speed Test ◽  
Machine Tool Structure

Analysis of the Coupled Vibration Between Feed Drive Systems and Machine Tool Structure

2015 ◽  
Vol 9 (6) ◽  
pp. 689-697 ◽  
Author(s):  
Ryuta Sato ◽  
◽  
Gen Tashiro ◽  
Keiichi Shirase ◽  
Keyword(s):  
Machine Tool ◽  
Degrees Of Freedom ◽  
Relative Displacement ◽  
Coupled Vibration ◽  
Motion Trajectories ◽  
Feed Drive ◽  
Proposed Model ◽  
Machine Tool Structure ◽  
Drive Systems ◽  
Feed Drive System

In this study, we have constructed a mathematical model that can analyze the coupled vibration of machine tool structure and feed drive systems. The model is proposed on the basis of the modal analysis of the actual machine tool structure. It consists of three translational and three rotational displacements of the bed, relative angular deformations between the bed and column, relative translational and angular deformations between the bed and saddle, and relative translational and angular deformations between the column and spindle head. In addition, each feed drive system is modeled using a vibration model, which has two degrees of freedom. The servo controllers of each axis are also modeled. To confirm the validity of the proposed model, frequency responses, motion trajectories of the feedback positions, linear scale positions, and the relative displacement between the table and head are measured and simulated. The effect of coupled vibrations on the tracking errors is examined with the help of both experiments and simulations. To investigate the effect of the servo systems on the vibration, both experiments and simulations are carried out by using feed drive systems in the following three conditions: mechanically clamped, servo-on, and servo-off. The results of experiments and the simulations show that the proposed model can express the mode of vibration and the influence of the condition of feed drive systems on the mode of vibration.

Modal Analysis of the Milling Machine Structure through FEM and Experimental Test

2011 ◽  
Vol 383-390 ◽  
pp. 6717-6721 ◽  
Author(s):  
S. Pedrammehr ◽  
Hamid Farrokhi ◽  
A. Khani Sheykh Rajab ◽  
S. Pakzad ◽  
M. Mahboubkhah ◽  
...  
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Modal Testing ◽  
Machining Process ◽  
Mode Shapes ◽  
Milling Machine ◽  
Machine Tool Structure ◽  
Tool Vibrations ◽  
Machine Structure

Machine tool vibrations have great impact on machining process. In this paper the dynamic behavior and modal parameters of milling machine is presented. For this purpose, the CAD model of the milling machine structure is provided in CATIA and then Natural frequencies and mode shapes of the machine tool structure are carried out through FEM modal analysis under ANSYS Workbench. The model is evaluated and corrected with experimental results by modal testing on FP4M milling machine. Finally, the natural frequencies and mode shapes obtained by both experimental and FEM modal analysis are compared. The results of two methods are in widely agreement.

Numerical Simulation of Solidification Process for a Machine Tool Bed

2011 ◽  
Vol 675-677 ◽  
pp. 987-990
Author(s):  
Ling Tang ◽  
Xu Dong Wang ◽  
Hai Jing Zhao ◽  
Man Yao
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Machine Tool ◽  
Computation Time ◽  
Solidification Process ◽  
Field Calculation ◽  
Original Design ◽  
Calculation Results ◽  
Improved Design

In this paper, the flow, heat transfer and stress during solidification process of the machine tool bed weighed about 2.5ton that has been optimized by structural topologymethod, was calculated with ProCAST software, and the causes of the crack forming in the casting of the machine tool bed was analysed. According to the calculation results, the structural design of the local part where cracks tends to form has been improved, and the heat transfer and the stress are calculated again. By comparing the temperature field with filling of molten cast iron and without filling, it has been found that there was little effect of filling on the results of temperature distribution of the cast, therefore the effect of filling can be ignored in the following temperature field calculation to save computation time. The model has been simplified in the stress field calculation with considering the complexity of the machine tool bed and the cost of computation. Then, the merits and demerits of the original design and the improved design are compared and analyzed depending on the calculated temperature and stress results. It is suggested that the improved one could get a more uniform temperature distribution and then the trend of the crack occurring can be greatly reduced. These results could provide a guide for the actual casting production, achieving the scientific control of the production of castings, ensuring the quality of the castings.

Dynamic Analysis and Experimental Research of Laser Cutting Machines

2014 ◽  
Vol 915-916 ◽  
pp. 31-34
Author(s):  
Qing Ping Zhang ◽  
Zheng Ru Wang ◽  
Yan Fang Wang
Keyword(s):  
Machine Tool ◽  
Modal Analysis ◽  
Laser Cutting ◽  
Machining Accuracy ◽  
Dynamics Analysis ◽  
Theoretical Base ◽  
Test Results ◽  
Cutting Machine ◽  
Manufacturing Errors ◽  
Theoretical Results

Vibration is one of the most important problems in laser cutting machine tool, which causes the manufacturing errors, also influences the machining accuracy of the parts. Modal analysis can calculate vibration type of structures. The paper presents how to use the powerful FEA software ANSYS to do the modal analysis on laser cutting machine tool and also studies the undamped free vibration on laser cutting machine tool. Finally, the test results and theoretical results were compared to verify the rationality of the modal, these provide theoretical base and conditions for dynamics analysis and optimal design.

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