• 한국생산제조학회지
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• 제7권4호
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• pp.104-116
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• 1998

This paper provides a review of the performance for SM45C using the CNC lathe. Under the constant cutting area, the tool wear for large feed rate is more than the small feed rate, and the progress goes more rapidly as the cutting speed is increased. This is caused by the friction between the workpiece and the bite. The average cutting force increases as the feedrate increases, and decreases as the cutting speed increases. This is because the effective rake/shear angle becomes smaller as the feedrate becomes larger. The higher is the cutting speed and the aspect ratio (the ratio for depth of cut to feedrate), the lower is the cutting force and the surface roughness. Also, for the optimal selection of the cutting conditions, many experimental graphical data were obtained. That is, the cutting force, the tool life, and the surface roughness were measured and investigated as the depth of cut and the feedrate changed. And the size effect was examined as the depth of the cut varied.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.135-138
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• 2009

In this study we investigate the machining characteristics of tool material for cold forging by using the machining center. The test was in the SKD62 cold forging material by 2-edge endmill with cutting fluid. The coating conditions are depth of cut 1,2,3mm. WC-endmill, federate 20mm/min, cutting velocity 20m/min. The surface roughness increase as the depth of cut increase. Also cutting force increase whiles the depth of cut increase.

• 한국정밀공학회지
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• 제13권4호
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• pp.61-66
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• 1996

The subsequent recrystallizations technique, and experimental strain measurement method by use of recrystallization phenomena, has been successfully applied for the observation of machined surface plastic zones with equivalent plastic strain .epsilon. .geq. 0.5, 0.12 and 0.02 of type 304 stainless steel. The depth of the zone with .epsilon. .geq. 0.5 is very small, 10-15 .mu. m, while those with .epsilon. .geq. 0.12 are 100-200 .mu. m and 200-450 .mu. m, respectively. The depths increase with increasing depth of cut and with decreasing rake angle. The relation between the depth of the zones and the cutting paramenters is shown. The deformation state ahead of the quick-stop cut was also well visualized by the technique.

• 한국정밀공학회지
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• 제16권4호통권97호
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• pp.220-228
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• 1999

The machining accuracy has been improved with the development of NC machine tools and cutting tools. However, it is difficult to obtain a high degree of accuracy when machining deep pocket with long end mill, since machining accuracy is mainly dependant on the stiffness of the cutting tool. To improve surface accuracy in machining deep pocket using end mill, the performance by down cut and up cut is compared theoretically and experimentally. To verify usefulness of up milling, various experiments were carried out. As a result, it is found that up milling produce more accurate surface than down milling in machining deep pocket. For effective application of up milling, various values in helix angle, number of teeth, radial depth of cut and axial depth of cut are applied in experiment.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.668-673
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• 1998

The specimen of current study has the same type with the 3-span slabs of Burns et al used in the study by Mojtahedi/Gamble, which laid a ground for the revision of the ACI318-77 code to the ACI 318-83 code. But those specimens was failed prematurely before it reached the ultimate strength which the specimen had. The reason is that bonded reinforcements were cut off where there is no need for the flexural reinforcement. As results. the slabs failed ultimately where the reinforcements was cut off. Thus, the tendon stresses of failure may have been much smaller than the values which culd reach if the bonded reinforcements were extended beyond the theoretical cut off points. On the based on the fact mentioned above. the specimens which had the same conditions as the specimens of Burns et al were used in the current study, but in which the reinforcements were distributed in a sequence for the reinforcements not to be cut anywhere in the 3-span. As a results, it was known that the current ACI code, revised by the result of Mojtahedi/Gamble's study, overestimated the effect of span/depth ratio on the members with high span/depth ratio. Thus it was concluded that the effect of span/depth ratio on the ultimate stress of unbonded tendon regulated by the current ACI code must be reconsidered and reevaluated.

• 한국생산제조학회지
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• 제6권3호
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• pp.17-25
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• 1997

This paper aims to clarify the effects of grinding conditions on the grinding force, ground surface and chipping size of workpiece in surface grinding of various ferrites with the resin bond diamond wheel. The main conclusions obtained were as follows: In a constant peripheral wheel speed, the specific grinding energy is fitted by straight lines with grinding depth coefficient($\delta$) in a logarithmic graph. The effect of both depth of cut and workpiece speed on grinding energy becomes larger in the order of Mn-Zn, Cu-Ni-Zn and Sr. When using the diamond grain of the lower toughness, the roughness of the ground surface becomes lower. The ground surfaces show that the fracture process during grinding becomes more brittle in the order of Sr, Mn-Zn and Cu-Ni-Zn. The chipping size at the corner of workpiece in grinding increases with the the increases of the depth of cut and workpiece speed, and the decrease of peripheral wheel speed. The effect of both depth of cut and workpiece speed on chipping size becomes more larger in the order of Sr, Mn-Zn and Cu-Ni-Zn.

• 한국정밀공학회지
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• 제15권2호
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• pp.114-123
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• 1998

In the end milling process, the information of the surface errors plays an important role in adaptive control systems for precision machining. As the measuring accuracy of the surface errors directly matches the control's, it is an important factor for evaluating the performance of the system. In order to obtain the surface errors, the prediction using the cutting force, torque, motor power etc. is frequently practiced owing to the easiness in measurement. In the implementation of the prediction, the information on the cutting depths make it concrete and precise. Actually the axial depth of cut limits the range of the calculation. In general, it is not easy to know the cutting depths due to irregular shape of workpieces, inaccurate positioning of them on the table of machine tool, and machining error in the previous cutting. In addition to, even if cutting depths are informed, it is difficult to match the individual position of the cutter on the varying shape of the work material. This work suggests an algorithm estimating the cutting depths based on cutting force and makes it precise to predict the surface error. The proposed algorithm can be applied in more extensive cutting situations, such as presence of the tool wear, change of the work material hardness, etc.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.173-178
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• 1995

This paper presents a new method to obtain parameters of end-mill cutting system. For high speed milling and precision surface finish, we have to predict the deflection of tool and the critical depth of cut. The cutting system can be modeled to a vibratory system to obtain the deflection of tooll and the critical depth of cut. A new method of the modeling of one degree of freedom system was developed using bisection method, ARMA(Autoregressive Moving average) and impact test.

• 대한기계학회논문집
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• 제18권5호
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• pp.1096-1105
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• 1994

A hypereutectic Aluminum-Silicon Alloy is widely used in the parts of automobile because of high-resistance and good strength. In this study, the cutting of hypereutectic A1-Si alloy for economical production was investigated by simulation. Tool life and the extraction rate of Si particles is inversely proportional to the depth of cut. When decreasing the depth of cut, the reduction of single crystal diamond tool cost and tool change time is achieved.

• 한국기계가공학회지
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• 제11권3호
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• pp.68-72
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• 2012

Al2017 is typical Duralumin of self-hardening aluminum alloy. It is lightweight, formability and machinability so throughout the industries have widely used automobile, electronics, semiconductor and aircraft as material. A variety of CNC machine tool processing technology, scientific principles and experience have been studied in order to increase accuracy and productivity. Using a machining center is to constant amount of side step and cutting characteristics studied changing depth of cut, revolution per minute and feed rate.