• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.888-891
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• 2000

Drilling is one of the most important operations in machining industry and usually the most efficient and economical method of cutting a hole in metal. From automobile parts to aircraft components, almost every manufactured product requires that holes are to be drilled for the purpose of assembly, creation of fluid passages, and so on. It is therefore desirable to monitor drill wear and hole quality changes during the hole drilling process. One important aspect in controlling the drilling process is drill wear status monitoring. With the monitoring, we may decide on optimal timing for tool change. The necessity of the detection of tool wear, fracture and the abnormal tool state has been emphasized in the machining process. Accordingly, this paper deals with the cutting characteristics of the hot-rolled high strength steels using common HSS drill. The performance variables include drill wear data obtained from drilling experiments conducted on the workpiece. The results are obtained from monitoring of the cutting force and Acoustic Emission (AE) signals, and from the detection of the abnormal tool state with the computer vision system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.1038-1042
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• 2002

Monitoring of the drill wear and hole quality change is conducted during the drilling process. Cutting force measured by tool dynamometer is a evident feature estimating abnormal state of drilling. One major difficulty in using tool dynamometer is that the work piece must be mounted on the dynamometer, and thus the machining process is disturbed and discontinuous. Acoustic transducer do not disturb the normal machining process, and provide a relatively easy way to monitor a machining process for industrial application. For this advantage, AE signal is used to estimate the abnormal state. In this study vision system is used to detect flank wear tendency and hole quality, there are many formal factors in hole quality decision circularity, cylindricity, straightness, and so on, but these are difficult to measure in on-line monitoring. The movement of hole center and increasement of hole diameter is presented to determine hole quality As the results of this experiment, AE RMS signal and measurements by vision system are shown the similar tendency as abnormal state of drilling. And detection of the abnormal states using BPNs was achieved 96.4% reliability.

• Journal of the Korean Society for Railway
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• v.18 no.5
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• pp.410-418
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• 2015

A slider of the pantograph undergoes uneven and abnormal wear due to sliding contact with the catenary. In the case of rain, the loss of lubricant increases the frictional resistance for the reciprocating motion between the catenary and the slider, accelerating local wear. The slider in the winter should have good wear resistance, which can be achieved through alloy design. Uneven and abnormal wear were not observed in the results of a driving test using a wear resistant slider. It was found that the increased density of the slider enhanced the corrosive effects of Fe-Ti, preventing the occurrence of abnormal wear by maintaining the wear and arc resistance in the rainy season. Also, mechanical and electrical wear did not affect the composition of the slider, and this improved the wear resistance. Inaddition, the slider was applied to an entire train and was tested during driving; ananalysis of the correlation of the catenary was performed, including during the rainy season and the winter season.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.346-349
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• 2015

Generally, in order to verify the degree of tire wear or abnormal wear, a driver or an auto mechanic checks the degree of tire wear and the existence of tire abnormality, directly with the naked eye or by way of using a gauge equipment. In case of such verification, individual subjective judgments may be involved or a driver may suffer heavy burdens to expend the time and cost for using the wheel alignment equipment. Therefore, this thesis will use a number of laser sensors to check the existence of abnormal wear and the degree of wear on each tire and develop a system checking the sides of tires to receive the tire information, so that subjective judgments may be overcome and objective and accurate judgments may be rendered.

• Journal of Korea Foundry Society
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• v.10 no.3
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• pp.235-246
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• 1990

This study has been carried out to investigate into the rolling wear characteristics of austempered ductile iron under unlubricated dry rolling condition by Amsler type test with 9.09% sliding ratio. Wear amount is increased with increasing of ferrite and retained austenite and it has been found that the amount of rolling wear is decreased when the hardness of matrix are higher. The rolling life up to generation of abnormal condition is conspicusly increased and amount of rolling wear is increased asrolling revolutionis increased and wear of austempered ductile ironunder dry rolling condition. Matrix has been obtained to upper bainite, low bainite at heat treatment, obtained to bull`s eye structure at as cast. It has been found that the amount of rolling wear is decreased when the tensile strength of the casting are increased and then the rolling life up to generation of abnormal wear in conspicuously increased and amount of wear was intend to graphite content.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.1021-1024
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• 2001

Out of all metal-cutting processes, the hole-making process is the most widely used. It is estimated to be more than 30% of the total metal-cutting process. It is therefore desirable to monitor and detect drill wear during the hole-drilling process. In this paper, the vision system of the sensing methods of drill flank wear on the basis of image processing is used to detect the wear pattern by non-contact and direct method and get the reliable wear information about drill. In image processing of acquired image, median filter is applied for noise removal. The vision flank wear area of the drill was measured. Backpropagation neural networks (BPns) were used for no-line detection of drill wear. The neural network consisted of three layers: input, hidden and output. The input vectors comprised of spindle rotational speed, feed rates, vision flank wear, thrust and torque signals. The output was the drill wear state which was either usable or failure. Drilling experiments with various spindle rotational speed and feed rates were carried out. The learning process was peformed effectively by utilizing backpropagation. The detection of the abnormal states using BPNs achieved 96.4% reliability even when the spindle rotational speed and feedrate were changed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.16-21
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• 2005

The cutting characteristics of hardened steel(AISI 52100) by PCBN tools is investigated with respect to cutting force, workpiece surface roughness and tool flank wear by the vision system. Hard Owning is carried out with various cutting conditions; spindle rotational speed, depth of cut and feed rate. Backpropagation neural networks(BPNs) are used for detection of tool wear. The input vectors of neural network comprise of spindle rotational speed, feed rates, vision flank wear, and thrust force signals. The output is the tool wear state which is either usable or failure. The detection of the abnormal states using BPNs achieves $96.8\%$ reliability even when the spindle rotational speed and feedrate are changed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.3
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• pp.8-16
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• 2003

Monitoring of the drill wear :md hole quality change is conducted during the drilling process. Cutting force measured by tool dynamometer is a evident feature estimating abnormal state of drilling. One major difficulty in using tool dynamometer is that the work-piece must be mounted on the dynamometer, and thus the machining process is disturbed and discontinuous. Acoustic transducer do not disturb the normal machining process and provide a relatively easy way to monitor a machining process for industrial application. for this advantage, AE signal is used to estimate the abnormal fate. In this study vision system is used to detect flank wear tendency and hole quality, there are many formal factors in hole quality decision circularity, cylindricity, straightness, and so of but these are difficult to measure in on-line monitoring. The movement of hole center and increasement of hole diameter is presented to determine hole quality. As the results of this experiment AE RMS signal and measurements by vision system are shorn the similar tendency as abnormal state of drilling.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.148-154
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• 1999

This study was carried out to verify grinding performance of dental diamond bur and investigate the possibility of AE application in dentistry field. Workpieces were made of acryl and bovine respectively for the experiments in this study. Grinding test was conducted to get the data of grinding resistance and specific grinding energy of four different types of diamond bur by using tool dynamometer. AE signal was acquired to verify grinding process in the AE measuring system. Tool wear was observed to find parameters about grinding characteristics of diamond bur by means of SEM picture. It was found that the wear of dental diamond bur could be detected with polishing of grinding material, removal of adhesive parts, wear of particles neighboring cutting nose, loss of material and elevation of temperature. The wear of B, C, D type diamond bur is due to wear and fracture of grain size. Abnormal state can be found through the behavior of AE signal in the grinding working. As a result, it is expected that forecast of abnormal state is possible using AE equipments under real time process.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.75-80
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• 2014

In previous study, make an attempt to estimate exhaust valve seat and seat-ring wear acceleration factor for engine durability test with measuring and consideration of wear mechanism. But found abnormal initial wear rate in exhaust valve seat-ring. And have to improve exhaust valve seat-ring wear rate for reliability reason, because next GDI/Turbo engine is based on this engine and GDI/Turbo engine have higher combustion pressure and higher thermal load. In this study, Trying to find the cause of abnormal wear factor, improve valve-train durability by change specification & design of parts and verify variant parts for improving durability of valve-train. And then I would like to propose a design guide line of valve-train system in a reliability point of view, besides make a complement of previous study.