The thermal effect on the lubricant of extrusion process

• Main Authors: Jen-Hua Yu, 于振華
• Other Authors: Tze-Chi Hsu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/35302669337842544983

碩士 === 元智大學 === 機械工程學系 === 90 === In cold forming of metals, one of the biggest problems is lubrication between the workpiece and the tool. Their surfaces slide under extremely high pressure beyond the yield value, producing large areas of chemically active nascent surface, and causing seizure. The main roles for the lubricant, then, are preventing seizure between the workpiece and the tool and alleviating deformation force. To prevent seizure, a phosphate coating method has been widely used and it requires many steps as well as complicated facilities. Although a method using oils alone without precoating is simpler, such a lubricating film is thin and apt to rupture easily. These drawbacks prevent extensive application. During forming, much heat is generated due to the deformation and friction, and a chemically nascent surface is produced. These are the main causes of seizure. The objective of this research is to investigate the antiseizure property of various extreme-pressure agents used in the extrusion processes. And then to maximize the property of the extrusion produces. Another goal of this research is to develop a realistic friction model used in the computer simulation of the extrusion processes. The model combines a rigid plasticity finite element code with a lubrication analysis. The effect of the surface roughness on lubrication flow is included by using the average Reynolds equation. The active lubrication regimes and appropriated friction factor can then be evaluated from the current local values of the interface variables.