• 한국정밀공학회지
• /
• 제26권3호
• /
• pp.73-80
• /
• 2009

In accordance with the trend for high-speed multi-axes, and the increasing technical sophistication of machine tools, thermal deformation has become an important factor in the accuracy of machine tools. It was analyzed that thermal deformation error accounts for about 70% of all errors made with machine tools. For precise temperature control, both cooling and heating should be implemented. A hot gas bypass type cooling cycle method has a simplified structure and temperature control accuracy to with in ${\pm}0.1^{\circ}C$. In this study, the performances of oil cooler system, including temperature controllability according to hot gas floe and preset temperature sustainability according to temperature load, were tested. It is expected that this study will contribute to the development and performances of oil cooler system, which could minimize thermal errors and improve the quality of precision machine tools.

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2017년도 추계학술발표회
• /
• pp.2-2
• /
• 2017

• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2017년도 추계학술발표회
• /
• pp.33-33
• /
• 2017

• 대한기계학회논문집
• /
• 제17권2호
• /
• pp.351-358
• /
• 1993

Recently a high speed spindle system for machine tools has attracted considerable attention to reduce the machining time, to improve the machining accuracy, to perform the machining of light metals and hard materials and to unite the cutting and grinding processes. In this study, a high speed spindle system is developed by applying the oil-air lubrication method, angular contact ball bearings, injection nozzles with dual orifices and so on. And a lubrication experiment for evaluating the performance of the spindle system is carried out. Especially, in order to establish the lubrication conditions related to the development of a high speed spindle system, the effects of oil supply rate, rotational spindle speed and so on are studied and discussed on the bearing temperature rise, bearing temperature distribution and frictional torque. And the effect of spindle system structure on the bearing temperature distribution is investigated.

• 한국기계가공학회지
• /
• 제14권4호
• /
• pp.85-91
• /
• 2015

Current world aircraft industry studies on the precision of the product are in active progress. Particularly in terms of improving the quality of processed products in terms of the surface roughness of the dimensional accuracy, fatigue strength, and corrosion resistance, which affect a lot of research on surface roughness, has been investigated. In this study of aluminum alloy, 7075 aircraft aluminum is used in a cutting CNC lathe machine for the cutting speed and feed rate according to the cutting experiments that were conducted. Additionally, the machine tool of the cooling method soluble cutting oil, insoluble cutting oil by cooling, and cooling the workpiece by cutting surface roughness will be investigated. Through the method and soluble cutting oil coolant cooled by the cutting speed increases, the value of surface roughness showed a regular result. Tool nose radius of 0.8 mm than 0.4 mm picture of when approximately 50 of the surface roughness values were less.

• 대한안전경영과학회지
• /
• 제22권2호
• /
• pp.39-46
• /
• 2020

This paper recognizes the risk of ignition of air fryer (machine that can cook fried dishes with hot air without oil) that is far exceeding the sales rate of microwave ovens, which is necessary to modern household kitchen, and identifies fire risk through the operation principle of the process of heat transfer, and the main structure of the machine. The fire test that we conducted is to observe the risk of ignition of the machine due to the damage to the safety system and the possibility of igniting oil paper along with food, to experiment with the possibility of ignition due to blockage of the exhaust due to obstacles, and accumulation of oil stains on the hot wire, and to present the method of fire control and devise countermeasures.

• Journal of Biosystems Engineering
• /
• 제40권2호
• /
• pp.137-144
• /
• 2015

Purpose: The high energy requirement of extraction of oil from jatropha seed and reduction of loss in oil content between whole seed and kernel of jatropha necessitate seed shelling. The purpose of this study is to develop and evaluate the performance of a jatropha seed shelling machine based on seed moisture content. Methods: A shelling machine was designed and constructed for jatropha seed. The components are frame, hopper, shelling chamber, concave, and blower with discharge units. The performance evaluation of the machine was carried out by determining parameters such as percentage of whole kernel recovered, percentage of broken kernel recovered, percentage of partially shelled seed, percentage of unshelled seed, machine capacity, machine efficiency, and shelling efficiency. All of the parameters were evaluated at five different moisture levels: 8.00%, 9.37%, 10.77%, 12.21%, and 13.68% w.b.). Results: The shelling efficiency of the machine increased with increase in seed moisture content; the percentage of whole kernel recovered and percentage of partially shelled seed decreased with increase in moisture content; and percentage of broken kernel, machine efficiency, and percentage of unshelled seed followed a sinusoidal trend with moisture content variation. Conclusion: The best operating condition for the shelling machine was at a moisture content of 8.00% w.b., at which the maximum percentage of whole kernel recovered was 23.23% at a shelling efficiency of 73.95%.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2003년도 춘계학술대회 논문집
• /
• pp.62-67
• /
• 2003

In this Paper, the dynamic temperature sensitivity and mu. temperature measurement errors of oil and air sensor in oil cooler are evaluated to predict design validity of sensors under special oil and atmosphere temperature changes. The temperature tracking of oil sensors for periodic temperature changes is simulated by obtaining thermal response coefficient from experiment. By this method, it is possible to design the optimal sensors with the admitted temperature measurement errors.

• 설비공학논문집
• /
• 제23권2호
• /
• pp.111-119
• /
• 2011

Recently, the performances of speed and accuracy are enhanced in machine tools. The high speed of the machine tools usually causes harmful thermal displacements on the objects. To reduce the thermal displacements, machine tools generally adopt oil coolers with precise temperature control function. This study aims at precise control of oil outlet temperature in the oil coolers with hot-gas bypass manner based on PI control logic. The control system was designed for obtaining steady state error within ${\pm}0.1^{\circ}C$ and maximum overshoot with 0.8% even though abrupt disturbances are added to the system. We showed that the PI gains could be easily decided by numerical simulations using practical transfer function which got experiments. Also, transient characteristics could be improved significantly by reflecting the inlet temperature of an evaporator to the output of a controller feedforwardly considering periodic abrupt disturbances. Through some experiments, excellent control performances were established by the suggested control.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2003년도 춘계학술대회 논문집
• /
• pp.93-98
• /
• 2003

High speed precision machines have been introduced to the CNC industry in order to improve productivity, shorten the appointed date of delivery and reduce the prime cost. High speed machines have more functions then general machines, and they were proved in performance. The production and sales of the high speed machines have been increased not only in domestic market but also all over the world. Accordingly, machines are faster, there are lots of problems to be solved. One of the most difficult problems is the thermal displacement on the main spindle due to generated heat while the spindle is rotated in high speed. Since the thermal displacement directly effects the quality of the machined parts, utmost efforts to minimize the thermal displacement have to be given from the beginning of designing machines. In practice, variety of methods are attempted and practiced to minimize the thermal displacement such as design of symmetrical frame, adoption of high speed bearings, application of compensation system using non-contact sensor and use of forced circulating lubrication system with oil cooler. Even if these variable methods have been practically used in the industrial field, generated heat has not been Perfectly Prevented lienee, in this paper, the characteristics of thermal displacement were investigated when several kinds of oil were tested for a high speed machine with forced circulating lubrication system within the same atmosphere and under the same conditions.