• Transactions of Materials Processing
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• v.27 no.5
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• pp.289-295
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• 2018

The profile ring rolling process can realize various ring shapes unlike conventional rectangular cross-sectional ring products. In this paper, the defective groove in the bottom surface of L-shaped ring products was analyzed. Grooves are generated by non-uniform external forces due to profile main roll and initial blank shape. Process parameters such as the motion of dies and working temperature were determined. Mechanism of groove formation was analyzed by FE simulation on the basis of local external forces acting on the blank. Analysis results were similar to the groove actually occurring in the production line. Based on results of the analysis, two solutions were proposed for the groove. The position of the base plate supporting the blank was adjusted and edge length of the main roll was extended to suppress growth of grooves. It has been verified that groove was improved by applying two proposed methods in the shop-floor.

• Journal of Advanced Marine Engineering and Technology
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• v.19 no.2
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• pp.47-55
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• 1995

When the low heavy oil is using as fuel oil to the diesel engine, some problems such as corrosion resistance, wear resistance and heat resistance are happened in diesel engine's internal material, especially the adhesive wear of piston ring groove was occurred as a important problem. Therefore to prevent adhesive wear of its groove, the surface of its groove used to be electroplated with Chrominum and for its Chromium electroplating, Fe anode is being used until nowadays because of its Special shape. However in case of using Fe anode, there were some problems such as deterioation of solution, property of Chromium film, and condition of coation. In this paper Pb anode electroplated withPb to the steel plate was investigated for its Chromium electroplating for Pb's high corrosion resistance in acid solution, and Pb anode is not dissolved compared with Fe anode and deterioration degree of solution in case of Pb anode is smaller than that of Fe anode and also property of Chromium film was better than that of Fe anode. Moreover it was known that the optimum cathodic current density for Pb electroplating to steel plate as insoluable anode for Chromium coating of piston ring groove is 30mA/$cm^2$ by experimental results obtained.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.859-863
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• 2004

Structural Dynamics Modification is very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material property, changing shape of structure. In this research, using the surface grooving technique, shape of base structure was changed to improve its first natural frequency. Utilizing the result of sensitivity analysis, groove shape was formed gathering the many small embossing elements. For this process, Sensitivity Criterion Factor was introduced. To reduce its amount of calculation, the range of target area was restricted to their neighboring area and that result was very successful.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.826-829
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• 2004

Structural Dynamics Modification is very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material property, changing shape of structure. In this research, using the surface grooving technique, shape of base structure was changed to improve its first natural frequency. Utilizing the result of frequency variation analysis, groove shape was formed gathering the many small embossing elements. For this process, Criterion Factor was introduced. To reduce its amount of calculation, the range of target area was restricted to their neighboring area and initial grooving point was selected using high-strain energy. This surface grooving technique was successfully applied to the HDD cover model.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.4
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• pp.1-7
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• 2010

Recently optical and electric and electronic forms in the field of ultra fine patterns has been used extensively, and techniques of the optical parts are required that can precision-machine this micro-patterns such as V or R-shaped micro-groove patterns. In this study, V and R type, shaping the way micro groove brass machining process to characterize the material feed rate and cutting depth and the V and R as a variable brother, using two kinds of diamond tools for each picture shape and surface roughness caused by conditions such as chips, processed through the analysis of effects of geometry and analysis such as precision machining.

• Tribology and Lubricants
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• v.35 no.6
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• pp.382-388
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• 2019

It is currently well known that surface textures act as lubricant reservoirs, entrap wear debris, and hydrodynamic bearings, which can lead to certain increases in load-carrying capacities. Until recently, the vast majority of research has focused on parallel sliding machine components such as thrust bearings, mechanical face seals, piston rings, etc. However, most sliding bearings have a convergent film shape in the sliding direction and their hydrodynamic pressure is mainly generated by the wedge action. Following the first part of the present study that investigates the effect of groove position on the lubrication performances of inclined slider bearings, this paper focuses on the effects of groove depths and film thicknesses. Using a commercial computational fluid dynamics (CFD) code, FLUENT, the continuity and Navier-Stokes equations are numerically analyzed. The results show that the film thickness and groove depth have a significant influence on the pressure distribution. The maximum pressure occurs at the groove depth where the vortex is found and, as the depth increases, the pressure decreases. There is also a groove depth to maximize the supporting load with the film thickness. The friction force acting on the slider decreases with deeper grooves. Therefore, properly designed groove depths, depending on the operating conditions, can improve the load-carrying capacity of inclined slider bearings as compared to the bearings without a groove.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.19 no.1
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• pp.51-56
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• 1983

In the stability problem of the U-grooved plate, it has a circular hole, the site of the hole determines some different deformation mode when it was loaded. To determine the optimal position of the circular hole-center which not to get large distortion of the hole itself, in this paper, we studied the distributions of stresses in the neck area between hole and U-groove and the distortion mode of the deformed hole by B.E.M(Boundary Element Method) and compared with experimental results in four cases. For a distributed load, according to the center of the hole moves closer to the U-groove center (c.-c. line), the shape of the circular hole was transformed to the elliptical one(it's major axis perpendicular to the c.-c. line). In this problem, the results by Boundary Element Method was well accorded with Experiments.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.3 s.96
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• pp.341-345
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• 2005

Structural Dynamics Modification (SDM) is a very effective technique to improve structure's dynamic characteristics by adding or removing auxiliary structures, changing material properties and shape of structure. Among those of SDM technique, the method to change shape of structure has been mostly relied on engineer's experience and trial-and-error process which are very time consuming. In order to develop a systematic method to change structure shape, surface grooving technique is studied. In this work, the shape of base structure was modified to improve its dynamic characteristics such as natural frequencies via surface grooving technique. Grooving shape was formed by mergingthe neighboring small embossing elements after analyzing frequency increment sensitivities of all the neighboring emboss elements. For this process, Criterion Factor was introduced and the initial grooving was started from the element having highest strain energy and the grooving is expanded into neighboring element. The range of targeting grooving area to check its frequency variations restricted to their neighboring area to reduce the computation effort. This surface grooving technique was successfully applied to a hard disk drives (HDD) cover model to raise its natural frequency by giving some groove on its surface.

• Tribology and Lubricants
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• v.35 no.6
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• pp.376-381
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• 2019

Surface texturing is widely applied to reduce friction and improve the reliability of machine elements. Despite extensive theoretical studies to date, most research has been limited to parallel thrust bearings, mechanical face seals, piston rings, etc. However, most sliding bearings have a convergent film shape in the sliding direction and the hydrodynamic pressure is mainly generated by the wedge action. The results of surface texturing on inclined slider bearings are largely insufficient. This paper is the first part of a recent study focusing on the effect of the groove position on the lubrication performances of inclined slider bearings. We model a slider bearing with one rectangular groove on a fixed pad and analyze the continuity and Navier-Stokes equations using a commercial computational fluid dynamics (CFD) code, FLUENT. The results show that the film convergence ratio and the groove position have a significant influence on the pressure and velocity distributions. There are groove positions to maximize the supporting load with the film convergence ratio and the groove reduces the frictional force acting on the slider. Therefore, the proper groove position not only improves the load-carrying capacity of the slider bearings but also reduces its frictional loss. The present results apply to various surface-textured sliding bearings and can lead to further studies.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.7
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• pp.1340-1347
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• 2002

Finite element simulations are being widely used to increase the efficiency and effectiveness of design of bulk metal forming processes. In such simulations, proper consideration of friction condition is crucial in obtaining reliable results. For this purpose, tip test based on backward extrusion was proposed recently. In this lest, a cylindrical billet is positioned in a shallow groove of a counter punch for centering purpose and formation of a radial tip is induced on the extruded end of the workpiece. In this study, the effect of centering groove on tip test was investigated. The quantitative ratio of the shear friction factors between the punch and die was numerically determined depending on the shape of centering groove. Also, surface expansion and pressure distribution along the punch and die were considered in order to better understand the reason that friction condition at the punch compared to the one of die was more severe.