• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 춘계학술대회 논문집(한국공작기계학회)
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• pp.149-154
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• 2001

This paper presents the experimental study of the static stiffness for the BT Shank(7/24 Long Taper) and the HSK Tool Shank(1/10 Short taper). The static stiffness test was performed under different experimental conditions. The results obtained are as follows ; As known in the analysis results of the Load-Deflection diagram of the 7/24 Test tool shank, it is turned out that the diagram is a linear characteristics without regard to axial drawing force and according as the axial drawing force get to the 6kN, the static stiffness of the shank increase linearly. Thus the effective axial drawing force which maintains the static stiffness of the Main spindle taper of Machine Tool is larger than 6kN. It is found that the Load-Deflection diagram with 6kN of drawing force in the 1/10 Test tool shank is characterized by non-linear. But according as the axial drawing force is increasing by the 8kN, the diagram is characterized by linear. And increasing amount of deflection is about 60%. Therefore commendable axial drawing force is larger than 8kN. As a result, considering that the actual drawing force of the Machining Center is about 1300kgf and axial drawing force 12kN is equivalent amount as a 1220kgf, it is turned out that 1/10 Test tool shank superior to 7/24 Test tool shank in the static stiffness.

• 한국정밀공학회지
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• 제18권8호
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• pp.48-53
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• 2001

In order to increase productivity and efficiency, high-speed rotating machines become popular these days. The high-speed rotating machine is likely to vibrate and cause machine failure even though it has small unbalance. Therefore, a balancing technique is studied in this paper. Off-line balancing methods are inadequate to solve unbalance vibration problem occurring in the field due to flexible rotor effect, faster tool change, and shorter spin-up and down, etc. An active balancing is suggested to allow re-balancing of the entire rotating assembly in the machine when a tool is changed. This paper shows how to identify the dynamics of the system using influence coefficient and suggest an active balancing technique based on influence coefficient method for high-speed spindle system.

• 대한기계학회논문집A
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• 제24권7호
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• pp.1681-1688
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• 2000

A dynamic model for the prediction of surface topography in high speed end milling process is developed. In this model the effect of tool runout, tool deflection and spindle vibration were taken in to account. An equivalent diameter of end mill is obtained by finite element method and tool deflection experiment. A modal parameter of machine tool is extracted by using frequency response function. The tool deflection, spindle vibration chip thickness and cutting force were calculated in dynamic cutting condition. The tooth pass is calculated at the current angular position for each point of contact between the tool and the workpiece. The new dynamic model for surface predition are compared with several investigated model. It is shown that new dynamic model is more effective to predict surface topography than other suggested models. In high speed end milling, the tool vibration has more effect on surface topography than the tool deflection.

• International Journal of Precision Engineering and Manufacturing
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• 제8권2호
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• pp.3-8
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• 2007

A machining system that generates accurate relative motions between the tool and workpiece is required to realize ultra precise machining or measurements. Accuracy improvements for each element of the machine are also required. This paper proposes a machining system that uses a compensation device for the six-degree-of-freedom (6-DOF) motion error between the tool and workpiece. The compensation device eliminates elastic and thermal errors of the joints and links due to temperature fluctuations and external forces. A hexapod parallel kinematics mechanism installed between the tool spindle and surface plate is passively actuated by a conventional machine. Then the parallel mechanism measures the 6-DOF motions. We describe the conception and fundamentals of the system and test a passively extensible strut with a compensation device for the joint errors.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.121-126
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• 2000

This research proposes a new advanced control method and demonstrates its realization in part. By incorporating shape machining and cutting force control at a time, this integrated scheme makes it possible to machine a desired shape and avoid the trouble of programming feedrate and spindle speed before machining and also reduce the shape error. The main idea proposed to achieve those goals consists in giving commanded path and desired cutting force at the same time. which makes it possible for position and force controller to distribute the corresponding velocity of individual axes and main spindle by an appropriate interpolation. That indicates we can replace the built-in interpolator of commercial machine tools by the developed algorithm.

• 한국공작기계학회논문집
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• 제16권6호
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• pp.9-14
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• 2007

In this paper, a rotating tool clamping device was developed based on a shape memory alloy(SMA) and its feasibility as a tool holder was experimentally explored. The SMA-based device was able to alter clamping to unclamping through temperature control within 1 second. The means and repeatability(${\sigma}$) of the tool clamping force were 185.5N and 6N respectively and its drifts were less than 3% for an hour. Considering the temperature hysteresis of the SMA-based tool clamping device, it is necessary to heat the SMA ring to around $50^{\circ}C$ after tool change to obtain more clamping force.

• 한국공작기계학회논문집
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• 제15권3호
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• pp.1-7
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• 2006

By the reason of increased demand of high productivity, the researches on manufacturing process and equipments for reducing cycle time have been made in many directions of a machine tool industries. Especially high productivity is very important to machining center with high-speed spindle. This paper proposed method of reducing T-T(tool to tool) time which results in shorter unclamping time. T-T time varies as factors such as a hydraulic system, a drawbar mass, a flow meter, a disc spring, piston and pipe diameters. In this paper We could find design factors has much influence on decreasing the unclamping time using DOE(Design of Experiment) and optimized the level of the factors using AMESim $4.0^{(R)}$ and visualNastran $4D^{(R)}$ Finally, we have verified improved result of the optimized factors with initial design.

• 한국정밀공학회지
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• 제23권3호
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• pp.139-146
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• 2006

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. For more quantitative analysis of a built-in motor's dynamic characteristics, that of tile mass and stillness effects are considered. And the drawbar in the spindle can be in various condition according to supporting stiffness between drawbar and shaft. Therefore, in this paper following items are performed and analyzed : 1. Modal characteristics of the spindle. 2. Analysis of rotor's mass and stiffness effects. 3. Modal characteristics of the spindle including drawbar, rotor and tool. The results show enough stiff supports must be provided between shaft and drawbar to prevent occurring drawbar vibration lower than the natural frequency of 1st bending mode of the spindle, and considering the mass and stiffness of built-in motor's rotor is important thing to derive more accurate results.

• 대한기계학회논문집A
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• 제20권5호
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• pp.1477-1485
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• 1996

Since the spindle bearing systme is the main source of the total cutting point compliance of machine tool structures, in this work, the static and dynamic characteristics of the spndle bearing systme driven by the gear located on the bearing span were investigated using analytical and finite elemtn methods to improve the performance of the spindle bearing system. Based on the theretical results, a specially designed prototype spindle bvearing systme was manufactured. Using the manufactured spindle bearing system, the static and dynamic characteristics were measured. From the comparison of the experimental results with the theoretical results, it was found that the finite elemetn method predicted well the static and dynamic characteristics of the spindle bearing system.

• 한국공작기계학회논문집
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• 제13권5호
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• pp.55-61
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• 2004

Chatter monitoring is also important for realizing an unmanned machining system. while many researches were done on this area, it is still a difficult job to detect very small amplitude amount of chattering. A monitoring system using a capacitive spindle displacement sensor was developed to monitor cutting vibration in turning in this research. The variance of the measured spindle displacement signals using the developed sensor was calculated and utilized to quantify the small vibration in machining. The results were compared with variance obtained using a tool dynamometer. The result showed that the developed system could be utilized in monitoring the subtle changes of cutting vibrations with high sensitivity confidence.