• Journal of the Korean Society for Precision Engineering
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• v.29 no.10
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• pp.1070-1077
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• 2012

Virtual machine tools have been magnified recently as manufacturers could estimate performances of machine tools before design and manufacturing of them. However, it requires much time and efforts to make FEM models and predict precision of machine tools well because machine tools are composed of many joints such as bolt joints, LM joints, rotational bearing joints and mounts. Especially, we have studied computational modeling methods of bolt joints to predict precision of machine tools well in this paper. Stiffness and damping coefficients of bolt joints are investigated and generalized with respect to fasten forces through experiments and FEM analysis. Matrix 27 element of ANSYS is used and bolt joints are simplified as square areas with 8 nodes to apply stiffness and damping simultaneously. Additionally, coordinate transformation of matrix 27 for bolt joints is induced to apply to skewed bolt joints of machine tools and evaluate it using FEM analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.378-381
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• 2003

Efficient development of method on a performance evaluation for machine tools has been regarded as the most important work for accuracy and quality enhancement to every user and manufacturer. A evaluation method of accuracy for machine tools has been studied recently according to the rapid increase of interest in precision machine tools. To this point of view, the circular interpolation test of machine tools is recognized as the most useful method to distinguish a dynamic accuracy of NC machine tools by ISO and ANSI/ASME, etc. In this paper, we have studied and developed the form measurement system with grid encoder to analyse the final accuracy of NC machine tools. we have analyzed the servo system error and geometric error of NC machine tools through measuring a dynamic error signal by this system. and then we verified the experimental result and enhanced the reliability by means of comparing the characteristics of the developed system with the kinematic ball-bar system.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.10
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• pp.1056-1061
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• 2012

FEM analysis is essential to shorten the development time and reduce the cost for developing high-performance machine tools. Mount joint parts play important role to ensure static and dynamic stability of machine tools. This paper suggests a computational modeling of mount joint part of machine tools. MATRIX27 element of ANSYS is adopted to model mount joint parts. MATRIX27 allows the definition of stiffness and damping matrices in matrix form. The matrix is assumed to relate two nodes, each with six degrees of freedom per node. Stiffness and damping values of commercial mount products are measured to build a database for FEM analysis. Jack mounts with rubber pad are exemplified in this paper. The database extracted from the experiments is also used to estimate of stiffness and damping of untested mounts. FEM analysis of machine tools system with the suggested mount computational model is performed. Static and dynamic results prove the feasibility of the suggested mount model.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1011-1017
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• 2011

Servo control loops are a core part in the control architecture of machine tools. Servo control loops manage acceleration, velocity and position of all the axes in a machine tool based on commands. The performance of servo control loops sets the basis for quality of production paris and cycle time reduction. First, this paper presents a general control architecture of machine tools and several control schemes in literature, which can be applicable to machine tools control; including Zero Phase Error Tracking Control (ZPETC) and Cross Coupling Control (CCC). After that, modem control strategies to mitigate the problem of high speed machining are reviewed. In high speed machining, high accelerations excite the machine structure up to high frequencies, thereby exciting the structure's modes of vibration. These structural vibrations need to be damped if accurate positioning or trajectory following is required. Input shaping is an attractive option in dealing with structural vibrations. The advantages and drawbacks of using input shaping technique for machine tools are discussed in detail.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.06a
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• pp.1-18
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• 2000

This paper describes firstly a prediction for desirable features of the machine tool in the year 2015 and beyond, and then delineates something definite in relation to some representative machine tools, which could be realised in very near future. The paper depicts furthermore another aspect of future machine tools, I. e., innovative structural designs. In addition, author asserts the importance of grass root-like knowledge, when predicting the desirable feature of machine tools future together with showing some evidences.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.869-877
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• 2011

In order to manufacture precision parts which are used for IT and BT Industry by machining, users need higher speed & precision machining center. So, for development of this kind of machine, we designed gantry type machining center which is piling of 3 axes on one moving body and the 2-axis rotary table is fixed on the base. It is applied linear motor that is instead of ball-screw and servo-motor combination and 50,000 rpm high-speed spindle. Composite material structure called mineral casting or resin concrete is applied also. This paper presents design technology and evaluated results of high speed and precision machining center.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.4
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• pp.7-15
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.991-994
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• 1995

Recent trend in machine tools is pursuing the high precision and high speed facility and its architecture is being more complicated. With this tendency, it is required the more precise dynamic analysis of electro-mechanical system in machine tools. In this paper, the exact mathematical model of feed and spindle system of a typical machine tools was induced. The feed system is modeled as 7-mass system including the workpiece and the spindle system as 4-mass system. The simulation results show that the induced model depicts the characteristics of real system very well. The effects of each mechanical element to dynamic motion of a machine are analyzed by simulation with the induced model. It ia anticipated that the induced model can be used in the analysis of various machine architectures and in the design stage of new machine tools.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.5
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• pp.461-466
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• 2013

In this paper, main mechanism and measurement method of energy consumption for machine tools are investigated by experiment and simulation. To evaluate total energy consumption of the machine tools, standard test workpiece and measuring method and test procedures are suggested. And, improvement of energy consumption evaluation by the motion kinematics theory is used. In addition, to estimate energy consumption of machine tools in design process, mass distribution of the structure and 5 axis motions are investigated and simulated by numerical analysis.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.2
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• pp.55-60
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• 2005

In order to develop the hydrostatic guideways driven by a core less linear motor for ultra precision machine tools, a prototype of guideway is designed and tested. A coreless linear DC motor with a continuous force of 156 N and a laser scale with a resolution of 0.01 ㎛ are used in the system. Experimental analysis on the static stiffness, motion errors, positioning error and its repeatability, micro step response and velocity variation of the guideway are performed. The guideway shows infinite stiffness within 50 N applied load in the feed direction, and by the motion error compensation method using the Active Controlled Capillary, 0.08 ㎛ linear motion error and 0.1 arcsec angular motion error are acquired. The guideway also reveals 0.21 ㎛ positioning error and 0.09 ㎛ repeatability, and it shows stable responses following a 0.01 ㎛ resolution step command. The velocity variation of feeding system is less than 0.6 ％. From these results, it is estimated that the hydrostatic guideway driven by a coreless linear motor is very useful for the ultra precision machine tools.