A new milling methodology with the equivalent normal curvature milling model machining freeform surfaces is proposed based on the normal curvature theorems on differential geometry. Moreover, a specialized whirlwind m...A new milling methodology with the equivalent normal curvature milling model machining freeform surfaces is proposed based on the normal curvature theorems on differential geometry. Moreover, a specialized whirlwind milling tool and a 5-axis CNC horizontal milling machine are introduced. This new milling model can efficiently enlarge the material removal volume at the tip of the whirlwind milling tool and improve the producing capacity. The machining strategy of this model is to regulate the orientation of the whirlwind milling tool relatively to the principal directions of the workpiece surface at the point of contact, so as to create a full match with collision avoidance between the workpiece surface and the symmetric rotational surface of the milling tool. The practical results show that this new milling model is an effective method in machining complex three- dimensional surfaces. This model has a good improvement on finishing machining time and scallop height in machining the freeform surfaces over other milling processes. Some actual examples for manufacturing the freeform surfaces with this new model are given.展开更多
Using brown .used alumina and top grade bauxite as main starting materials, ultrafine alumina, silica fume, and pure calcium aluminate cement as bonding system, the effcts of brown filsed alumina and top grade bauxite...Using brown .used alumina and top grade bauxite as main starting materials, ultrafine alumina, silica fume, and pure calcium aluminate cement as bonding system, the effcts of brown filsed alumina and top grade bauxite additions on the properties and microstructure of zero-cement Al2O3-SiO2 castables after dried at 110 ℃C and fired at 1 250℃ for 3 h were studied. The micro- structure was analyzed and discussed. The results show that the hot modulus of rupture of zero-cement Al2O3 - SiO2 castables at 1 250℃ is up to 22. 1 MPa when the bauxite addition is optimum at 12.5 wt%. The mullite formation mechanism in this castables is dissolutionprecipitation mechanism and the hot modulus of rupture of the castables is closely related to in-situ mullite formation. Compared with brown fused alumina, the top grade bauxite is more helpful to in-situ mullite formation and improvement of hot modulus of rupture of the castables.展开更多
基金China Postdoctoral Science Foundation(No.2005037348)Science and Technology Research Program of Hubei Province,Ministry of Education,China(No.D200612003)
文摘A new milling methodology with the equivalent normal curvature milling model machining freeform surfaces is proposed based on the normal curvature theorems on differential geometry. Moreover, a specialized whirlwind milling tool and a 5-axis CNC horizontal milling machine are introduced. This new milling model can efficiently enlarge the material removal volume at the tip of the whirlwind milling tool and improve the producing capacity. The machining strategy of this model is to regulate the orientation of the whirlwind milling tool relatively to the principal directions of the workpiece surface at the point of contact, so as to create a full match with collision avoidance between the workpiece surface and the symmetric rotational surface of the milling tool. The practical results show that this new milling model is an effective method in machining complex three- dimensional surfaces. This model has a good improvement on finishing machining time and scallop height in machining the freeform surfaces over other milling processes. Some actual examples for manufacturing the freeform surfaces with this new model are given.
文摘Using brown .used alumina and top grade bauxite as main starting materials, ultrafine alumina, silica fume, and pure calcium aluminate cement as bonding system, the effcts of brown filsed alumina and top grade bauxite additions on the properties and microstructure of zero-cement Al2O3-SiO2 castables after dried at 110 ℃C and fired at 1 250℃ for 3 h were studied. The micro- structure was analyzed and discussed. The results show that the hot modulus of rupture of zero-cement Al2O3 - SiO2 castables at 1 250℃ is up to 22. 1 MPa when the bauxite addition is optimum at 12.5 wt%. The mullite formation mechanism in this castables is dissolutionprecipitation mechanism and the hot modulus of rupture of the castables is closely related to in-situ mullite formation. Compared with brown fused alumina, the top grade bauxite is more helpful to in-situ mullite formation and improvement of hot modulus of rupture of the castables.
