Investigation of Semi/Near-Dry Machining for Ecology in Thermal Engineering

热工中半/近干式加工的生态学研究

基本信息

批准号：
14550196
负责人：
OHTAKE Hiroyasu
金额：
$ 2.37万
依托单位：
Kogakuin University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2004
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14550196/
关键词：
Mechanical Engineering Thermal Engineering Heat Transfer Mist Cooling Machining Correlations and Modeling Evaporation Boiling Ecology 整理式・モデリング整理式

项目摘要

A kind of semi or near dry machining is Minimum Quantity Lubrication. The machining is expected as an Ecological technology. In the method, material is cut with lubrication blended on the basis of vegetable oils of a few cc/h. The liquid also serves as coolant during the machining. In this study, heat transfer characteristics in mist cooling with commercial machining oil and water were investigated experimentally and analytically. Especially, the heat transfer in the mist cooling was examined focusing on the effects of droplet size, droplet velocity and liquid mass flux on the heat transfer characteristics.Steady state experiments of heat transfer were conducted using a pure copper cylinder and mist flow of commercial machining oil or pure water with air at room temperature. Liquid flow rates were 0.3,0.9,1.8,4 and l/hr, respectively ; each air flow rate was 0,40,75 and 120 l_N/min.Experimental results showed that heat fluxes increased with an increasing liquid flow rate for every air flow rate. Maximum cooling rate in the present experimental range was 6 MW/m^2. The heat transfer mechanism in oil mist was only cooling of liquid film without boiling formed on a heated surface, whereas the heat transfer mechanism in water mist cooling was classified into three regions: non-boiling, evaporation of droplets and evaporation of the liquid film. A cooling limit (critical heat flux-CHF-) model of water mist flow was presented by focusing on maximum evaporation rate of liquid mass flux on a heater. The heat transfer coefficient in oil mist was well expressed by the heat removal capacity on sensible heat of supplying oil-droplets to the heated surface. Finally, four dimensionless correlations of heat transfer were derived from a dimension analysis and experimental data for both the water mist flow and the oil mist flow.

半干式或近干式加工的一种是微量润滑。该加工有望成为一种生态技术。在该方法中，通过以几cc/h的植物油为基础混合润滑来切割材料。该液体还在加工过程中充当冷却剂。在这项研究中，通过实验和分析研究了商业加工油和水雾冷却的传热特性。特别是，研究了雾冷却中的传热，重点关注液滴尺寸、液滴速度和液体质量通量对传热特性的影响。利用纯铜圆柱体和商业加工的雾流进行了稳态传热实验。油或纯净水与空气在室温下。液体流速分别为0.3、0.9、1.8、4和l/hr；每种空气流量分别为0、40、75和120 l_N/min。实验结果表明，对于每种空气流量，热通量随着液体流量的增加而增加。当前实验范围内的最大冷却速率为6 MW/m^2。油雾冷却的传热机理仅是液膜冷却，而不会在受热表面形成沸腾，而水雾冷却的传热机理分为三个区域：非沸腾、液滴蒸发和液膜蒸发。以加热器上液体质量通量的最大蒸发速率为研究对象，提出了水雾流的冷却极限（临界热通量-CHF-）模型。油雾中的传热系数可以通过向受热表面供应油滴的显热的散热能力来很好地表达。最后，根据水雾流和油雾流的量纲分析和实验数据，得出了传热的四个无量纲相关性。