Analysis and Optimisation of Structural Dynamics of Machine Tools by a Synthesis of Dynamic Rigidity Program System

Author(s):  
Masataka Yoshimura
Author(s):  
Lei Yang ◽  
Xing Zhang ◽  
Lei Wang ◽  
Wanhua Zhao

During the working process of high-speed multiaxis machine tools, inertial forces can cause vibration and deformation of mechanical structure, which lead to the dynamic error of tool center point (TCP) relative to worktable and can adversely affect the machining performance. Considering the varying feed positions and accelerations during machining, a parameter-varying multi-rigid-body dynamic model of a 3-axis gantry machine tool is proposed. This model represents the position dependent structural dynamics and inertial forces, which can simulate the dynamic error of TCP relative to worktable within the entire workspace. The results show that the dynamic error in one direction is affected by the feed motions of multiple feed axes. The magnitudes of the dynamic error significantly vary with the position of Z-axis. And the dynamic errors in Y- and Z-direction show different varying trends. Then the theoretical model is used to discuss the dynamic error and position dependency. The expressions of TCP dynamic response and inertial forces reveal the reason why the dynamic errors in Y- and Z-direction show different varying trends.


Author(s):  
T Kobayashi ◽  
M Burdekin

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.


Impact ◽  
2021 ◽  
Vol 2021 (1) ◽  
pp. 15-17
Author(s):  
Yum Ji Chan

Precision machinery has come a long way over the years. Factories that once relied on manpower now use machines, and this development has brought with it innumerable benefits including improvements to accuracy, repeatability, productivity and efficiency. Naturally, though, machines are imperfect in that precision of a batch of machines vary slightly. On top of that, machines experience wear and tear or even break-downs. These unpredictable events can be costly to manufacturers. This is why research to better understand factors that affect a machine's precision is important. This knowledge can be used to reduce the issues that occur with machine tools and thereby maximise the efficiency and quality of production. This is the goal of Dr Yum-Ji Chan, Department of Mechanical Engineering, National Chung Hsing University, Taiwan. His research on vibration engineering, structural dynamics and the dynamics of rotors is seeking to better understand machine tools and, in doing so, improve their performance. He believes more research is required to understand the behaviour of specific components in machine tools, and he is seeking to fill this gap in knowledge. This involves understanding the vibration phenomena that occur in components in machine tools and, to do so, Chan and his team are producing accurate dynamic behaviour in machine tool models. This will, in turn, enable researchers to develop virtual machine tools that can monitor the condition of machines.


2005 ◽  
Vol 128 (1) ◽  
pp. 194-203 ◽  
Author(s):  
Sang Won Lee ◽  
Rhett Mayor ◽  
Jun Ni

Miniaturized machine tools, referred to as mesoscale machine tools (mMTs) henceforth, have been proposed as a way to manufacture micro/mesoscale mechanical components. A thorough study of the dynamic behavior of the mMT is required for the successful development of its machine structure. This paper demonstrates the development of an mMT, the performance evaluation of its mesoscale milling process, and the characterization of its dynamic behavior. The mMT is developed by using an air turbine spindle and three piezoelectric linear stages, and its volumetric size is 150×70×140mm. A series of micro/mesoscale milling experiments are conducted, and the performances in the developed mMT testbed are evaluated. The dynamic characteristics of the mMT can be different from those of conventional machine tools because the mMT is a miniaturized structure and comprises different machine components. Therefore, the effect of the miniaturization of a structure on the change of its dynamic behavior, called scaling law of the structural dynamics, is studied numerically and experimentally. The dynamic characteristics of the developed mMT that are estimated from the scaling law of the structural dynamics are much different from those obtained from an experimental modal analysis, and the flexible joints of the developed mMT are mainly responsible for this significant difference. Therefore, the joint dynamics of the mMT are studied by introducing an equivalent lumped parameter model, thus enabling simple identification of the joint dynamics and the effective modification of its critical joints to enhance a machining performance.


2006 ◽  
Vol 304-305 ◽  
pp. 483-487
Author(s):  
Xian Guo Han ◽  
Wu Yi Chen ◽  
B. Huang ◽  
Shao Hong Wang

The development of a virtual axis cutter grinder was introduced. The main contents of this paper include layout design, parameters design method, control system and program system. The purpose of the development of the parallel machine tools is for cutter grinding. The dimension of the cutter and the translation workspace for cutter grinding usually is small and is therefore suitable for the parallel machine tool application. The new machine tool has high rigidity and good precision.


2020 ◽  
Vol 110 (09) ◽  
pp. 624-628
Author(s):  
Maximilian Busch ◽  
Thomas Semm ◽  
Michael Zäh

Industrieroboter werden aufgrund ihres großen Arbeitsraumes zunehmend für die Fräsbearbeitungen großer Werkstücke eingesetzt. Dynamische Instabilitäten während des Prozesses schränken jedoch ihre Produktivität ein. Maschinelle Lernverfahren gewinnen hierbei an Popularität, um Strukturmodelle aus experimentellen Daten abzuleiten. Das Institut für Werkzeugmaschinen und Betriebswissenschaften (iwb) der Technischen Universität München entwickelt in Zuge dessen Methoden, die mit maschinellen Lernverfahren Simulations- und Experimentaldaten verbinden, um dadurch die Strukturdynamik von Fräsrobotern zu modellieren.   Industrial robots are increasingly used for milling applications of large workpieces due to their large working area. However, dynamic instabilities during the process limit their productivity. Thus, machine learning methods are becoming increasingly popular for deriving system models from experimental data. The Institute for Machine Tools and Industrial Management (iwb) at the Technical University of Munich is developing methods to fuse simulation data and experimental data using machine learning methods to model the structural dynamics of milling robots.


2015 ◽  
Vol 9 (6) ◽  
pp. 679-679
Author(s):  
Hidenori Shinno

Demands for machine tools that are highly accurate, productive, flexible, and compact have been growing in the aerospace, automotive, energy, factory automation, and other industries. Rationally meeting these severe, complex requirements has led to numerous research and development activities involving machine tools. Few machine tool technologies have been established, however, despite the machine tool industry’s long history. Within the next several years, the rapid change and enlargement of the This mini special issue on machine tool structure and its design optimization features 8 papers classified under the following themes: - Enhancing high static and dynamic rigidity - Minimizing and optimizing thermal deformation - Proposing new structural analysis methods for machine tools - Selecting and applying new structural materials to the machinetool structure - Applying new structural designs and mechanisms These papers present new design concepts, design methods, and innovative examples in machine tool development. I believe that successfully combining these core technologies will provide machine tool compatible with future manufacturing environments. In closing, I would like to express my sincere gratitude to the authors and reviewers for their interesting and dedicated contributions to this special issue.


2010 ◽  
Vol 129-131 ◽  
pp. 814-818
Author(s):  
Ru Fu Hu ◽  
Xiao Ping Chen

Structural dynamics optimal design of key components is basis to reach optimal design of whole machine tool. The method of sensitivity analysis is applied to optimize the arrangement shapes and parameters of the strengthened bars of components. The BP neural networks model of the spindle system is established and corrected based on comparing with the experimental result, and the structure parameters of the spindle are optimized. These technologies will benefit to realize optimal design of whole NC internal grinder and guide dynamic optimal design of other machine tools.


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