The Development Of The CAPP System For Flashless Forging Of Gear Blanks And Its Design Technology Of Preforging And Die

The CAPP system for flashless forging of gear blanks is a computer aided forging process and die design software which is developed for a company, AutoCAD is used as drawing platform and VBA as visual developing tool. After perfecting the structure and function of the system the preforging process and die structure are systemically and widely studied.The system is divided into four function modules based on the design route of forming process: input module of the gear blank information, forging design module, processing parameters design module and the die structure design module. The coordination and communication of each module is realized by the main control module, that is by the system menu and running control program. The forging drawings and the forging procedure card are created by AutoCAD ActiveX technology. The databases related to the forgings are managed by MicrosoftAccess. The user interfaces are designed by VBA language. The forging parameters can be modified and confirmed in the system interactively, also forging drawings, process card, die structure optimization and die drawings can be displayed according to the parameters.Some relations during the design are integrated with the executive program by making use of the programming technique of VBA language, realize the parametrizaltion of each part and assembly drawing by the form of procedure drive.Preforming design is one of important contents in the forging process design, which is a transitional figure to the forming of complex forging, it will affect the flowing condition of metal in the cavity, eventually affect the final shape and the forming quantity. The forging shape is kaleidoscopical, shape of preforming could be various, which lead to the difficulty of preforming design. In general preforming design come through trial and error such as initial design, verifying the design result, modifying design and re-verifying, it depends on the experience of designer greatly, furthermore the adjustment of the die is difficult. Based on summing up and tiding up large quantity examples of preforging, analyzing metal flow law of gear blank forging, according to the existing principle of axisymmetric forging, a suitable design rule to the complex preforging of gearblank is given.At the same time the hot preforging drawing is given which provides the reference to the die impression of preforging and structural dimension.The calculation of processing parameters such as heating-up time and deformation resistance are discussed in the thesis.On the basis of analyzing every kind of common die structure, die structure adopt the form of combination die which composed of die body and pre-stress ring, furthermore choose to the reasonable beam pad structure.The universalization, standardization and seriation of die can increase the production rate. During die design, it is significant to use the universal die sets. Therefore group the forgings according to their diameter to each press, design the combination die according to the maximum forging diameter of each group. So use the die body and pre-stress ring with the same outside diameter to the same press. Thus different forgings can be produced by the same die sets in the same press.The system has many advantages such as having friendly interface, strong practicability, the normalization and standardization of die design. The successful development of the system to expand the fine forging process of gear blank, alleviate to the heavy labor of designer, shorten process designtime and guarantee the quantity of the process design have the obvious significance.