Modeling of water and lubricant sprays in hot metal working
Spray cooling and lubrication are used in hot metal working such as forging industry. Proper selection of lubricant spray and cooling helps increase die life, improve part quality, protect operation environment, minimize waste, and enhance overall productivity. Understanding of this process will result in sprays-on-demand in terms of heat transfer and friction design. Modeling of water and lubricant sprays has significant impact on the performance of spraying systems, and on the hot metal working processes on which it applied. This research focuses on developing a more complete understanding of spray cooling effects on hot forging process by modeling the thermal-steady state temperature of tool, modeling of droplet spread and evaporation on the tool surface, modeling of space- and time- averaged cooling rate and film formation in lubricant. The sprays modeling is broke down to two parallel approaches. The first approach is to study heat transfer in the forging cycle, the relationship between cooling control and forging performance, and the optimal design of cooling rate. It has been shown via numerical simulations that discrete cooling rate design can improve forging performance. An upfront method Thermal-Steady State Balance method was developed combining one dimensional heat conduction algorithm with FEA simulation to predict temperature evolution and thermal steady state temperature distribution, and to optimize cooling rate considering the full forging cycle. The second one starts from a macro view of traditional sprays system and connects it to a micro view of single lubricant droplet impingement by focusing on the material being sprayed and the spray parameters. In the effort to bring sprays design and cooling management together, a statistical model is developed to address the gap between hydrodynamic and thermodynamics of droplet impingement and global sprays design on cooling rate and lubricant film formation. A two-step spray approach which separates water spray from lubricant spray was studied in transient simulation and recommended for dual objectives of heat transfer and lubricant film formation. The results confirm that the prediction of heat transfer and film formation links sprays process with forging process and facilitates in the design and optimization of both processes.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:spray heat transfer lubrication forging modeling
Date of Publication:01/01/2007