• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 제35회 춘계학술대회
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• pp.240-247
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• 2002

The rolling wear behavior of SM55C is investigated under lubrication. This is a comparative tribological behavior of heat treatment effect for SM55C. Rolling wear test method is used for Ball-on-disk type. Specimens can be classified into two main groups: as-annealing and non-annealing. As result of wear behavior, flanking initial time of non-annealing specimen keep at retard but it have not under high normal load. One of the notable features of annealing specimen is steady flanking initial time for a normal load in this experiment. Failure mechanism of SM55C is due to the fatigue wear such like flanking, pitting etc.. Flanking leads to abruptly fracture of worn surface. Fracture mechanism has a connection with normal load and polishing direction of specimens.

• Tribology and Lubricants
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• 제7권1호
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• pp.40-45
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• 1991

Wear performances for dibutyl 3,5-di-t-butyl 4-hydroxy benzyl phosphonate (DBP) were invesitigated using the four ball test machine under sliding and also rolling contact conditions, and compared with ZDDP. DBP showed excellent antiwear performace compared with ZDDP under severe sliding contact. Also, DBP achieved a longer fatigue life than ZDDP under rolling contact conditions. The surface of the worn balls was observed using an optical microscope, and the wear derbis generated was measured using the Particle Quantifier (PQ).

• 한국정밀공학회지
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• 제19권6호
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• pp.96-103
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• 2002

The objective of this study is to adjust the roll gap fur the dimension accuracy of bar in hot bar rolling process considering roll wear. In this study hot bar rolling processes fur round and oval passes have been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental from and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the effects of thermal softening of DCI (Ductile Cast Iron) roll material according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering curve. The new technique developed in this study for adjusting roll gap can give more systematically and economically feasible means to improve the dimension accuracy of bar with full usefulness and generality.

• International Journal of Precision Engineering and Manufacturing
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• 제4권1호
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• pp.56-62
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• 2003

The objective of this study is to adjust the roll gap for the dimension accuracy of bar in hot bar rolling process considering roll wear. In this study hot bar rolling processes for round and oval passes have been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental form and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the effects of thermal softening of DCI (Ductile Cast Iron) roll material according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering curve. The new technique developed in this study for adjusting roll gap can give more systematically and economically feasible means to improve the dimension accuracy of bar with full usefulness and generality.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.1036-1041
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• 1997

The objective of this study is to adjust the roll gap for the dimension accuracy of bar in hot bar rolling process considering roll wear. In this study hot bar rolling processes for round and oval passes have been investigated. In order to predict the roll wear, the wear model is reformulated as an incremental form and then wear depth of roll is calculated at each deformation step on contact area using the results of finite element analysis, such as relative sliding velocity and normal pressure at contact area. Archard's wear model was applied to predict the roll wear. To know the effects of thermal softening of DCI (Ductile Cast Iron) roll material according to operating conditions, high temperature micro hardness test is executed and a new wear model has been proposed by considering the thermal softening of DCI roll expressed in terms of the main tempering curve. The new technique developed in this study for adjusting roll gap can give more systematically and economically feasible means to improve the dimension accuracy of bar with full usefulness and generality.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.105-113
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• 2001

The effect of silver particle introduction on the rolling friction of AISI 52100 steel pairs has been investigated. Experiments were performed in dry conditions using a thrust bearing-type rolling test rig at a load range of 12 - 960 N and a sliding velocity range of 8 - 785 mm/sec with pure(99.99%) silver particles. Results showed that the introduced silver particles formed transfer layer, which protected virgin bearing surfaces and resulted in low rolling friction. By changing the quantity of silver particles, transitions in the rolling friction wear found. Results also showed that the variations in normal load and rolling speed also affected the rolling friction behavior. Analyses using SEM and EPMA showed that tile formation of transfer layer was mainly governed by the silver particle quantity, normal load and rolling speed, and this resulted in the different behavior of rolling friction. In this study, it was found that the low and stable rolling friction was resulted from the shakedown phenomena occurred at the silver transfer layer.

• 열처리공학회지
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• 제21권6호
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• pp.314-319
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• 2008

• 한국정밀공학회지
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• 제29권4호
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• pp.409-416
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• 2012

Recently, surface modification technology is of importance to improve the wear resistance and the corrosive resistance for high accurate mechanical parts such as LM guide, Ball Screw and Roller Bearing etc., Those has generally featured on rolling contact mechanism to improve not only the wear and the friction, but also the accuracy and the corrosion performances. For surface modifications of high accurate mechanical parts, normally thermal spray, PVD, CVD and E.P. processes have been used with many materials such as DLC, raydent, W, Ni, Ti etc. Diamondlike carbon (DLC) films possess a combination of attractive properties and have been largely employed to modify the tribological behaviors such as friction, wear, corrosion, fretting fatigue, biocompatibility, etc. However, for rolling contact mechanism mechanical parts DLC films are needed to study for commercial benefit. Rolling contact mechanism has features on effects of cyclic motions and stresses, and also not simply sliding motions. The papers focused on the performance test of wear and corrosive resistance according to Me-DLC film thickness. And also, its thickness effect of wear analysis was carried out through the simulation of the maximum shear stress under the rolling contact surface. As the results, Me-DLC films have more potential to improve the wear resistance for high precision mechanical parts than raydent films.

• 한국재료학회지
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• 제21권6호
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• pp.334-340
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• 2011

Saw wires have been widely used in industries to slice silicon (Si) ingots into thin wafers for semiconductor fabrication. This study investigated the microstructural and mechanical properties, such as abrasive wear and tensile properties, of a saw wire sample of 0.84 wt.% carbon steel with a 120 ${\mu}M$ diameter. The samples were subjected to heat treatment at different linear velocities of the wire during the patenting process and two different wear tests were performed, 2-body abrasive wear (grinding) and 3-body abrasive wear (rolling wear) tests. With an increasing linear velocity of the wire, the tensile strength and microhardness of the samples increased, whereas the interlamellar spacing in a pearlite structure decreased. The wear properties from the grinding and rolling wear tests exhibited an opposite tendency. The weight loss resulting from grinding was mainly affected by the tensile strength and microhardness, while the diameter loss obtained from rolling wear was affected by elongation or ductility of the samples. This result demonstrates that the wear mechanism in the 3-body wear test is much different from that for the 2-body abrasive wear test. The ultra-high tensile strength of the saw wire produced by the drawing process was attributed to the pearlite microstructure with very small interlamellar spacing as well as the high density of dislocation.

• 한국철도학회논문집
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• 제8권5호
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• pp.477-482
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• 2005

Through a year's commercial operation, Korea High Speed Railway has solved defectives from several breakages at the beginning and is going into the stage of stable operation. Among issues, wheel wear becomes a matter of primary concerns in view of vehicle's stability and maintenance. It was understood as above that wear status has been improved in the test by which railway system including vehicles and tracks was stabilized during a year's commercial operation, comparing to that with excessive wear in the trial operation prior to opening to the public. To make out wheel's wear status and characteristics of equivalent conicity at present when the service has been introduced a year ago and the average cumulative mileage of vehicles reach almost 500,000km, wheel's wear types were analyzed with the current vehicles in service.