Five-Axis Numerical Control Processing Application and Surface Quality Control of HyperMILL-Based Mobile Phone Mold Cavity
The mold cavity structure of mobile phones is one of the most typical complex surface structures. Specific to this type of product, this paper takes some typical product as an example, to conduct Hyper Mill-based analysis and computation for surface processing quality control problem in numerical control milling on the basis of the analysis of traditional mobile phone cavity processing. The description of five-axis processing and path as well as VERICUT simulation is explained with the final application verification. The result shows that the quality control formula of the processing surface is consistent with the actual situation, and the advantages of five-axis processing technology in the application of such types of products are clarified as well.
EQUIVALENT NORMAL CURVATURE APPROACH MILLING MODEL OF MACHINING FREEFORM SURFACES
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.
Numerical and experimental investigation on air distributor design of fluidized bed reactor of sawdust pyrolysis
Abstract An improved biomass conversion in a lab-scale fluidized bed reactor (FBR) is achieved by optimizing the air distributor orifice size and number. Two approaches for introducing air were numerically and experimentally examined. These included perforated plate and downward orifice sparger. 3 mm and 5 mm orifice diameters, and 7, 9 and 13 holes were simulated at flow velocities of 2, 4, 6, and 8 times the minimum fluidization velocity, Umf. The simulation results revealed that increasing the orifice number has a positive effect on gas holdup, particularly for the perforated plate, which showed a uniform distribution of bubbles. The sparger configuration produced larger bubbles sizes, which could lead to better recirculation of solid flux, while stagnant particle zones were observed at the lower section of both distributors. A pyrolysis unit is also inserted at the top of freeboard of the FBR. For perforated plate with 6Umf, the pyrolysis process achieved thermal and cold gas efficiencies of 82.91% and 52.03%, respectively, while combustible gases with 41.6%mol CO, 8.7%mol CH 4 and 2.17%mol HC, were obtained. For sparger pipe and 6U mf _sp, 35.33 ppm NOx and 111 ppm SO 2 were measured in flue gas from combustion process at bed region.