| Blades are a series of parts in the aero-engine with different sizes and various shapes. They are mainly used to converse thermal energy into mechanical energy. Blades especially turbine blades work at very severe environments with high temperature, high pressure, high-speed, high-corrosion, which required that they have high strength and excellent comprehensive mechanical properties. In order to meet some special aerodynamic performance, not only a complex geometry is needed, but also high surface roughness and machining accuracy. To achieve the above requirements, special processing is needed. Among all kinds of methods, die forming process is widely used, not only because of its high efficiency but also its capacity to obtain fine microstructure. Forging process involves the design of high-precision forging die, which further requires us to design the reasonable blade parts and corresponding forgings.In blade forging and die designing, traditional manual design method and two-dimensional design method can no longer meet the current need, three-dimensional CAD software is used extensively nowadays. Most three-dimensional software are common software, which not directed at a specific area. With such software for manual design, there are a lot of things to do. Taking into account the existence of substantial repetitive work during the design process, computer-aided design is a good solution. In this paper, according to a special blade data format, with the second development interface UG/Open API provided by UG, programs were written with C language to complete a specific CAD system for the design of forging blade and trimming die.The main contents in this paper include:(1) First, Excel was used to manage the design data of blade body in order to simplify the data preparing, reading and writing process, meanwhile, the maintaining of data consistency was also considered.(2) According to the fact that side points are more intensive than that in the blade basin and back curve, side points are being separated, and then appropriate side circles were being fitted from side points with the least square idea.(3) Blade basin and back curves were being fitted with quasi uniform cubic spline, and a fairness algorithm was used to make them more smoothing.This algorithm obtaining fairness effect through the adjustment of control point of spline curve.(4) The designing of blade part which include:the extensive of blade tip and root, polynomial fitting of blade basin and back curve, solution of balance angle, coordinate transformation, the insertion of rabbet and other auxiliary operations. Among them, the solution of largest inscribed circle of blade section was studied especially. (5)The designing of blade forging which mainly include:obtain discrete points from blade body, add margin to the blade body and rabbet, envelope and draft of rabbet, insertion of locating convex and other auxiliary operations.(6) Design of the Trimming die which include:Parameterization of trimming die moldbase, extraction of parting lines, the generation of cutting edges of die, and also the production of punch, and material-removal board.The blade design CAD system integrated seamlessly with UG software, it is user-friendly, very easy to operate, and it can reduce designers' workload greatly and thus shorten the design cycle. Above all, it has a certain practical application value. |
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