Dynamic Characteristics of a Machine Tool at Working Positions in Operating Test

2011 ◽  
Author(s):  
Huimin Dong ◽  
Yang Tan ◽  
Delun Wang ◽  
Yali Ma
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Dynamic Properties ◽  
Vibration Energy ◽  
Testing Method ◽  
Spring Element ◽  
Machining Center ◽  
Brick Element ◽  
Stiffness And Damping

A machine tool is an assembly structure fitted by some moveable substructures, which the relative motion between the substructures creates normal and limit operating positions. Along with the substructures moving, the distributions of masses, stiffness and damping of the machine in space vary, leading to variety of structure distributions and dynamic properties. For exploring the dynamic properties distributions of machine tools, this paper presents a testing method under practical operational excitations, which is under operating excitations from remaining unbalanced value in the spindle, and collecting vibration signals of time and frequency at the spindle foreside at working positions. To identify resonance characteristics, a judging matrix is established by comparing vibration energy and vibration amplitude at 1st octave. By this method, MDH50 active pole horizontal machining center is tested, and the dynamic characteristics is determined. It reveals that dynamic characteristics of resonance come from the substructure independent resonance and their superposition in operating excitation. For verifying this result, FEA is conducted, in which 20 nodes brick element and spring element are applied to build the model entities and interfaces. The analysis result by FEM is consistent to the testing results. The research provides foundation for how setting up machining programs to avoid the resonance vibration of the machine in the operating.

Dynamic Characteristics Optimization of Joint Interface of Machine Tool Based on Porous Oily Materials

2014 ◽  
Vol 709 ◽  
pp. 63-67
Author(s):  
Jian Feng Ma ◽  
Qiang Li ◽  
Ji Kun Feng ◽  
Liang Sheng Wu
Keyword(s):  
Porous Material ◽  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Unit Area ◽  
Test System ◽  
Joint Interface ◽  
Characteristic Parameters ◽  
Damping Characteristics ◽  
Stiffness And Damping

The joint interface plays a significant role in machine tools and other machineries. A novel type of joint which consists of oily porous material was proposed in the paper. A test system for identifying the unit area dynamic characteristic parameters of Fe-based joint interfaces were represented. The stiffness and damping parameters were compare to the conversional structures. The result showed that the joint which contains an oil film interlayer formed by porous and steel was superior to the joint with non-media formed by steel in stiffness and damping characteristics. In the case of the same preload, the former’s stiffness is increased by about 50 %, and the damping is increased about five to six times.

Dynamic Characteristics of Rotating and Nonrotating Machine Tool Spindles

1974 ◽  
Vol 96 (1) ◽  
pp. 343-347 ◽  
Author(s):  
R. J. Allemang ◽  
H. Thomas Graef ◽  
C. D. Powell
Keyword(s):  
Machine Tool ◽  
Frequency Response ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Vibration Testing ◽  
Pulse Technique ◽  
Dynamic Conditions ◽  
Testing Method ◽  
Rotating Machine ◽  
Pulse Testing

The initial concern of this paper is to establish the general relationships between vibration testing using a static machine tool, and vibration testing using a machine tool under dynamic conditions, obtaining the frequency response by a pulse technique. The application of pulse testing to determine the dynamic characteristics of a rotating machine tool spindle is investigated. The characteristics of a static spindle are contrasted with the characteristics at different rotational speeds of the same spindle while also noting any effect of table feed. The capabilities, advantages, and limitations of the testing method are discussed with respect to mounting conditions and physical aspects of the machine tools examined.

Mechanical and dynamic properties of alternate materials for machine tool structures: A review

2018 ◽  
Vol 37 (24) ◽  
pp. 1456-1467 ◽  
Author(s):  
S Murugan ◽  
PR Thyla
Keyword(s):  
Composite Materials ◽  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Large Scale ◽  
Dynamic Properties ◽  
Research Work ◽  
Present Review ◽  
High Speeds ◽  
Machine Tool Structures

Machine tool structures find large-scale applications in various machining industries due to their necessity to design several kinds of machines. However, the vibration produced on machining is a significant problem which has to be overcome. To suppress the vibration, several researchers have attempted to enhance the machine tool structure’s dynamic characteristics in the recent past. The composite materials have risen up as a new kind of material for the manufacture of machine tool structures with producing lesser vibrations since the past few decades. To increase the production of precision products, machining should be done at high speeds without producing vibration. The dynamic characteristics such as natural frequency as well as damping of machine tool structures are very important parameters. Hence, the improvement of these parameters is nothing but the improvement of dynamic characteristics, as said earlier. Therefore, the present review elaborates various available reports on the improved dynamic characteristics of machine tools. The review focused mainly on mechanical and dynamic properties of alternate materials for machine tools with different composite materials. Furthermore, conflicting conditions of suitable alternate material for the preparation of machine tools are also focused in the present review. To the best of our knowledge, the review on the use of alternate materials for the manufacturing of machine tool structures has not been reported elsewhere and hence the present review will provide useful information for subsequent researchers to enhance the scope of research work in the area of manufacturing machine tool structures.

Design Optimization of Machine-Tool Structures With Respect to Dynamic Characteristics

1983 ◽  
Vol 105 (1) ◽  
pp. 88-96 ◽  
Author(s):  
M. Yoshimura ◽  
T. Hamada ◽  
K. Yura ◽  
K. Hitomi
Keyword(s):  
Machine Tool ◽  
Design Optimization ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Structural Model ◽  
Optimization Method ◽  
Practical Applications ◽  
Design Variables ◽  
Design Changes ◽  
Machine Tool Structures

This paper proposes a design optimization method in which simplified structural models and standard mathematical programming methods are employed in order to optimize the dynamic characteristics of machine-tool structures in practical applications. This method is composed of three phases: (1) simplification, (2) optimization, and (3) realization. As design variables employed in this optimization are greatly reduced, machine-tool structures are optimized effectively in practice. With large design changes being conducted through this multiphase procedure, dynamic characteristics of machine tools can be greatly improved. This method is demonstrated on a structural model of a vertical lathe.

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.

Optimized Design and Performance Study of High Speed Five-Axis Machine Tools

2020 ◽  
Author(s):  
Tzu-Chi Chan ◽  
Jyun-Sian Yang
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
High Speed ◽  
Spectral Response ◽  
Work Piece ◽  
Static And Dynamic Characteristics ◽  
Five Axis ◽  
Speed Accuracy ◽  
Machine Structure

Abstract With the development of machine tools trending toward high precision, intelligence, multi-axis, and high speed, the improvement of the processing performance and rigidity of the machine is considerably important. The objective of this study is to design of a high-speed five-axis moving-column machine tool and perform structural analysis and optimization. We study the static and dynamic characteristics of the five-axis machine tool, design and improve the mechanical structure, and optimize the structural configuration of the machine. The entire machine structure is further analyzed and enhanced to improve its static and dynamic characteristics, including static rigidity, modal, transient, and spectral response characteristics. The static and dynamic characteristics of the machine structure directly affect the machine processing performance, and further affect the work piece precision machined by the tool. Through this study, the design technology for speed, accuracy, and surface roughness of the machine tool are further improved.

Structural investigation of steel-reinforced epoxy granite machine tool column by finite element analysis

2019 ◽  
Vol 233 (11) ◽  
pp. 2267-2279 ◽  
Author(s):  
Prabhu Raja Venugopal ◽  
M Kalayarasan ◽  
PR Thyla ◽  
PV Mohanram ◽  
Mahendrakumar Nataraj ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cast Iron ◽  
Machine Tool ◽  
Dynamic Characteristics ◽  
Element Model ◽  
Static Stiffness ◽  
Element Analysis ◽  
Static And Dynamic Characteristics ◽  
Machining Center

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.

Modal Modeling of Micro-Machining Center

2012 ◽  
Author(s):  
Marcin Chodźko ◽  
Krzysztof Marchelek
Keyword(s):  
Machine Tool ◽  
Model Updating ◽  
Dynamic Properties ◽  
Modal Testing ◽  
Mode Shapes ◽  
Experimental Investigations ◽  
Micro Machining ◽  
Machining Center ◽  
Modal Model ◽  
The Impact

Modeling of dynamic properties of machine tools has a significant influence on improvement of its construction. This process is extremely important when a new construction of machine tool is under development. Experimental modal analysis provides information about frequency bandwidths with significant amplitudes of resonances, damping values and mode shapes. This information can be used in FEM model updating, stability prediction or finding weak elements of the machine tool structure as well. In the paper the modal model of prototype of the micro machining center is presented. Polymax algorithm was used to estimate the poles (frequency, damping) of modal model and modal shapes. Modal model was built on the basis of the impact test results. Methodology of conducted experimental test is presented. Tested machine tool was made of different materials (steel, aluminum, stone and others) which causes difficulties during experimental investigations. In the construction different types of guideways were implemented — rolling, slide and pneumatic ones. Maximum rotational speed of the tool is about 100 000 rev/min, so the frequency range where poles of modal model are estimated is wide (high frequencies of excitation during machining). Weight of sensors used during testing is an important issue due to a low mass of the structure. Also the excitation of the structure is troublesome because of vulnerability of precise guideways and forces sensors used in machine tool construction. Validation of the modal model is also presented in the paper and practical problems of modal testing are discussed.

Optimization Method of Machining Center Multi-Joint Stiffness Based on Orthogonal Experiment and FEA

2011 ◽  
Vol 697-698 ◽  
pp. 253-257
Author(s):  
Ming Nan Sun ◽  
Guo Fu Yin ◽  
Liang Mi
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Discrete Optimization ◽  
Orthogonal Experiment ◽  
Joint Stiffness ◽  
Optimization Method ◽  
Mean Frequency ◽  
Machining Center ◽  
Orthogonal Optimization ◽  
Significant Factors

Machine tool joint stiffness has important affects on the dynamic characteristics of the whole machine tool. It is a challenging task to optimize multi-joint stiffness of the overall structure. By discussing the distribution of stiffness of linear guides, ball screws, bolt joints and bearings, a discrete optimization method of multi-joint stiffness of a machining center was presented based on orthogonal experiment and FEA. Mean frequency formulation was adopted to define the index of orthogonal optimization. According to the principle of orthogonal experiment, optimization levels were found out, sequence of the factors on the index of the orthogonal experiment was listed and significant factors were determined. Results of this research proved the validity and feasibility of the discrete optimization method of multi-joint stiffness of the whole machine tool by combining orthogonal experiment and FEA.

The Effects of the Damping Characteristics of Slideways on the Dynamic Characteristics of Workpiece Fixtures Mounted on Machine Tool Tables

1994 ◽  
Vol 208 (4) ◽  
pp. 245-251
Author(s):  
T Kobayashi ◽  
M Burdekin
Keyword(s):  
Machine Tool ◽  
Dynamic Characteristics ◽  
Machine Tools ◽  
Design Criterion ◽  
Damping Characteristics ◽  
Machine Tool Structures ◽  
Dynamic Rigidity ◽  
Cutting Point

Not only dynamic characteristics of machine tool structures but also those of workpiece fixtures are important in machine tools as they directly influence the dynamic rigidity at a cutting point. In this paper, the effects of damping characteristics of slideways on the dynamic characteristics of workpiece fixtures mounted on machine tool tables have been clarified both theoretically and experimentally. Furthermore, a design criterion of workpiece fixtures has been suggested.

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