• 한국공작기계학회논문집
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• 제12권4호
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• pp.77-84
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• 2003

The properties of a machine tool greatly affect machining quality since a machine tool has large variance in its features. Machine tool makers want to find best machining condition with the one that they have built. Machine builders need to develop test specimen since it helps finding characteristics of machine tools when the machining properties of the specimen are analyzed. This paper develops test specimen to identify features of the main spindle, the feeding device, and the frame of a machine tool. The specimen is machined with a high speed machine and the features of the machine are analyzed with test items. They are surface roughness, overshoot in axial movement, errors in circular movement, feeding with small movement and compensational error. This work can improve usability for a machine tool in machining practice.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.106-112
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• 2003

High-speed machining is one of the most effective technology to improve productivity. Because of the high speed and high feed rate, high-speed machining can give great advantages for the machining of dies and molds. This paper describes on the improvement of machining accuracy in high-speed machining and an estimate about machining accuracy of high-speed machining.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.460-465
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• 2003

High-speed machining is one of the most effective technology to improve productivity. Because of the high speed and high feed rate, high-speed machining can give great advantages fur the machining of dies and molds. This paper describes on the improvement of machining accuracy in high-speed machining and an estimate about machining accuracy of high-speed machining.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.977-981
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• 2000

Direct drive linear motors have large potential for use as high speed machine tool feed units since they can increase machining rates and improve servo accuracy by eliminating gear related machining problems. So, in this paper, characteristic of 2-axis linear motor feed unit are studied and control gain are adjusted considering positioning, velocity, acceleration and static stiffness. We confirm linear motor feed unit are affected value of control gain sensitively, because drive directly. From the experiment, this feed unit has l${\mu}{\textrm}{m}$ micro step resolution, 5.7${\mu}{\textrm}{m}$ positioning accuracy and under 60${\mu}{\textrm}{m}$ circularity.

• 한국정밀공학회지
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• 제24권2호
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• pp.127-133
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• 2007

The spindle system with a built-in motor can be used to simplify the structure of machine tools, to improve the machining flexibility of machine tools, and to perform the high speed machining. To improve the competition power of price to quality, spindle design is very important. Because it possesses over 10 percent of machine tool's price. The latest machine tools have rotational frequency and excellent about might and precision cutting. So it requires static and dynamic strength in the load aspect. In conclusion, the deformation of the spindle end have to extremely small displacement in static and dynamic load. In this study, On the assumption that the bearings that are supporting 24,000rpm high-speed spindle are selected in the most optimum condition, the natural frequency and deformation of the spindle end is obtained by FEM mode analysis. The Taguchi Method was used to draw optimized condition of bearing position and it's stiffness.

• 산업기술연구
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• 제33권A호
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• pp.31-39
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• 2013

There are two methods to make a distinction of deterioration of high-speed railway track. One is that an administrator checks for each attribute value of track induction data represented in graph and determines whether maintenance is needed or not. The other is that an administrator checks for monthly trend of attribute value of the corresponding section and determines whether maintenance is needed or not. But these methods have a weak point that it takes longer times to make decisions as the amount of track induction data increases. As a field of artificial intelligence, the method that a computer makes a distinction of deterioration of high-speed railway track automatically is based on machine learning. Types of machine learning algorism are classified into four type: supervised learning, unsupervised learning, semi-supervised learning, and reinforcement learning. This research uses supervised learning that analogizes a separating function form training data. The method suggested in this research uses SVM classifier which is a main type of supervised learning and shows higher efficiency binary classification problem. and it grasps the difference between two groups of data and makes a distinction of deterioration of high-speed railway track.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권8호
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• pp.400-407
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• 1999

This paper treated the design, manufacture and the performance characteristics under each mode of high speed motor/generator for an electro-mechanical battery(EMB). This machine is employed as an integral part of a flywheel energy storage system(FESS), i.e., a modular flywheel system to be used as a device for storing electrical or mechanical energy. In this machine, the magnetic field system is constructed by using special magnet array, dipole Halbach array with 16 permanent magnet segments and the armature is composed of a plastic bobbin and multi-phase windings with Litz wire. The magnet array produces a highly uniform dipole field without back iron. The motor/generator is 3-phase machine in which the dipole Halbach array surrounding the winding is rotating. Since there are no iron laminations, this field system offers some unique advantages for the simplicity of the design and the theoretical prediction of characteristics of a high speed electric machine. This paper describes the results obtained when EMB system was tested in the laboratory.

• 한국공작기계학회논문집
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• 제13권1호
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• pp.1-8
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• 2004

Thermal distortion is a critical issue in machine tools, especially in high speed machining. This is the reason why recent machine tools have thermal compensation function. To compensate thermal distortion, it is necessary to make a model that has some relationship between temperature and deformation. Various experimental methods ye widely been used in thermal test: constant spindle speed, unit step speed increase, random spindle speed, etc. This paper focuses on which type of spindle operation condition is good for thermal experiment. Also, experimental data is modeled using multiple linear regression models and compared each other to select a method. Consequently, it turned out at e condition of 75％ constant of maximum spindle speed is good enough to generate temperature and distortion data.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.223-226
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• 2002

To maximize the productivity in machining molds and dies, machine tools should operate at high speeds. However, the productivity of mold manufacturing has not increased significantly because CNC milling machines have massive slides, which do not allow rapid acceleration and deceleration during the frequent starts/stops encountered in machining molds and dies. This paper presents the use of composites for these slides to overcome this limitation. The vertical and horizontal slides of a large CNC machine were constructed by bonding high-modulus carbon-fiber epoxy composite sandwiches to welded steel structures using adhesives. These composite structures reduced the weight of the vertical and horizontal slides by 34% and 26%, respectively, and increased damping by 1.5 to 5.7 times without sacrificing the stiffness. Without much tuning, this machine had a positional accuracy of $\pm5\mu\textrm{m}$ per 300 m of the slide displacement.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.36-40
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• 2002

The development of feed drive system with high speed and accuracy has been a major issue in the machine tool industry. Linear motors can be used as the efficient tool to achieve fast feed mechanism and high accuracy. However. a high speed feed drive system with linear motors can generate heat problems such as the variation of temperature distribution and the resultant thermal stress. In this paper, the important heat sources and the resultant thermal errors are presented. The thermal deformation characteristics of the machine tool with linear motors were identified, which are thermal expansion of linear scale, shrinkage, expansion and bending in the machine tool structure.