• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.173-180
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• 2000

In the process of grinding a long slender type workpiece, such as ballscrew, by the external cylindrical grinding machine, the cylindricity of the workpiece depends on the distance of rests, the stiffness of supports, the diameter and material of workpiece. Conventionally the process needs to be supported by one or more rests to prevent static deflection and vibration. In this paper, the optimal position of the rests was investigated in order to minimize the cylindricity due to the static deflection, by taking compliance of the workpiece and structure into account. In order to obtain the optimal position of rests, a new modeling that is considering the spring effect of all support elements was established. Since it is so complicated to obtain the optimal position analytically for various conditions due to discontinuity, a genetic algorithm u as utilized.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.1000-1004
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• 1995

In the case of the external cylindrical grinding machine, the grinding mechanism can cause a wheel to vibrate due to a wheel cutter. This phenomena will bring about the unsymmetric wear up to high frequency without any relation of rotational speed. So far, when the grinding spindle is analyzed, it is assumed that a wheel is considered as lumped mass at the endof a beam. Nowadays, there is a tendency to use the wheel with a lsrge diameter or CBN wheel to achieve the high speed and accuracy grinding performance. Therefore, this kind of assumption is no longer valid. At the analysis of the grinding spindle, the parameter which dapends on the dynamic characteristics is a combination force between each part. For example, there is the tightness torque of a bolt and taper element in the grindle. In addition, the material property of the wheel can contribute the dynamic characteristics. This paper shows the mode participation of the shell mode of the wheel in the grindle and the dynamic characteristics according to the parameters which are the configuration of the flange and tightness torque of a bolt and taper. Modal parameter of the wheel, flange and the spindle can be extracted through frequency response function obtained by modal test. After that, by changing the tightness torque and kinds of wheel, we could accomplish the test in the whole combined grinding spindle. To perform modal analysis of vibration characteristics in the grinding spindle, we could develop the model of finite element method.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.1
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• pp.62-69
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• 1993

The accuracy of machine tools is the major factor concerned with the acuracy of the processed work. The feed errors of feed system in machine tool, therfore, make the machining errors of work directly on processing. In this point, this study focused on the generative elements of feed errors in CNC cylindrical grinding machine, such as supporting method of ball screw, the effect of pitch and yaw error and the position detecting method in servo system when operating its shaft of grinding wheel head. Furthermore, in order to improve the driving accuracy of this machine tool, feed errors are measured by a laser interferometer. Results obtained in this study provide some useful informations to attain high accuracy of CNC machine tool.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.258-261
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• 2002

In this study, micro tools(WC) to produce micro-structure and parts, were fabricated ell a cylindrical grinding machine using ELID(Electrolytic In-process Dressing) technique. The shape of the micro-carbide tool was square, corn. The size of the micro-carbide tool was measured less than 10$\mu\textrm{m}$ respectively by SEM(Scanning Electron Microscope). Furthermore, we fabricated micro structure by different processing methods on the desk top cylindrical grinding machine. The manufactured shape was like a tower and the measurement showed that the endpoint of micro structure was $50{\times}50$$\mu{\textrm}{m}$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.555-559
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• 1996

Based on the general drill grinding mechanism, termed the helical grinding system, the conceptual design of 5 axes CNC drill grinding machine is proposed. Unique determination of the grinding parameters for precise production of the desired flank geometry is discussed by utilizing a mathematical model. Also, different combinations of grinding parameters are mentioned in order to produce various drill geometries (conical, cylindrical, and planar drill) on the single proposed CNC machine. A manual helical grinding machine has been fabricated and consequently helical drills have been ground in order to check the feasibility of the proposed grinding mechanism and its functionality.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.164-174
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• 1996

As tools for machining precision componants, end mills and ball end mills are widely used. For the end mills have longer cylindrical shape comparing dianeter, they are liable to deflect when machining and induce geometrical error and deterioration of surface roughness. To improve the stiffness and the sharpness of the cutting edge of end mill, a software for manufacturing end mills are developed. The program predicts the result of helical flute grinding and the configuration of cuting edge which is located in cylindrical surface. Furthermore to facilitate the manufacturing end mills using CNC grinding machine, the setting condition which satisfy the geometrical requirements like tool rake angle and stiffness are obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.318-318
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• 2004

원통 연삭기(cylindrical grinding machine)는 원통형 공작물을 센터나 척으로 지지하면서 연삭 공정을 수행하기 때문에 연속적인 작업이 어렵지만, 무심 연삭기(centerless grinding machine)는 원통형 공작물을 받침판으로 지지하면서 연삭 숫돌(grinding wheel)과 조정 숫돌(regulating wheel)로 연삭 공정과 축방향 이송을 동시에 수행하기 때문에 연속적인 작업이 가능하다. 특히 고정밀 부품을 작업자의 숙련도와 무관하게 고능률적으로 가공할 수 있는 무심 연삭기는 구름 베어링, 축, 피스톤 핀 등과 같은 고정밀 기계류 부품들을 대량 연삭하기 위한 용도로 많이 사용되어 왔다.(중략)

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.315-320
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• 2001

Ultra-abrasives such as diamond and CBN have used to maintain accuracy and form deviation for superalloy etc. This study contains the dry cylindrical grinding of metals with Vitrified-bond CBN wheel and Resinoid-bond CBN wheel. For various condition of grinding speed, workpiece speed, grinding depth and feed speed of table, the grinding resistance, the surface roughness, and material removal are measured and discussed.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.204-209
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• 1999

The dressing time monitoring in cylindrical grinding is very important with respect to machining efficiency. Therefore, the purpose of this paper is to determine the wheel life by monitoring behavior of grinding power for Wa, 19A and GC. For this purpose, we investigated indirectly the attritious wear of grain edge, the loading of grinding wheel and the breakage of grain through the grinding power and the surface roughness under various grinding conditions. From obtained the results, the relationship between the wheel life and the average sectional chip area is examined to guide for the determination of dressing time.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.20-27
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• 2000

A chatter vibration and a workpiece burn are the main phenomena to be monitored in modern grinding processes. This study describes a trouble diagnosis of the cylindrical plunge grinding process using the power and acoustic emission (AE) signals. The raw signals of the power and the AE occurred during the grinding operation were sampled and analyzed to determine the relationship between each fault and change of signals. A neural network that has a high success rate of the fault detection was used. Furthermore, an analysis on the influence of parameters to the chatter vibration and the grinding burn was conducted.