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Abstract: The splitting spinning which is designed to split a rotational disk blank into two flanges, is one of newly rising, green flexible forming technologies, and it can be widely applied to manufacture a whole pulley or wheel in fields of aerospace, automobile and train. The investigation of forming parameters influencing on splitting spinning force can provide the foundation for the choice of equipments, the design of dies and the determination of processing parameters. This paper aims at developing a reasonable formula between splitting spinning force and forming parameters by the principal stress method, and then the reliability of the formula is verified by the comparisons with experimental data. Meanwhile, both a reasonable method of calculating the three-dimensional projected areas and a more effective method of solving the average angle in the deformation zone are presented. Furthermore, based on the formula, the laws of initial thickness and initial diameter of workpiece, diameter and splitting angle of splitting roller and feed ratio of splitting spinning influencing on splitting spinning force are investigated. The achievements may serve as an important guide for the determination and optimization of forming parameters of splitting spinning. [Copyright &y& Elsevier]

Abstract: Cold cross-wedge rolling process is utilized to enhance the surface hardness and the strength in a round shaped part. Main geometrical design parameters in a cold cross-wedge rolling die are the forming angle, the spreading angle, and the die height. General defects in this process are an excessive slip on the surface and a hole generation at the center point which is usually called as the Mannesmann hole defect. The friction coefficient and geometrical design variables affect occurrences of an excessive slip and/or a central hole generation. In this paper, effects of the forming angle and the friction coefficient on the initiation of the Mannesmann hole defect are analyzed by using a response surface method. Integrals of four different ductile fracture models are compared with a history of the effective plastic strain at the central point. It reveals that the maximum effective plastic strain at the point can be utilized to determine the initiation point of the ductile fracture in the cold cross-wedge rolling process. Optimization of design parameters for prevention of the Mannesmann hole defect initiation is carried out using a response surface method. As results, that the forming angle of 25° and the spreading angle of 1° can be proper design conditions with the prevention of occurrences of internal hole defect and an excessive slip. Optimum design specification is testified by the experimental result. [Copyright &y& Elsevier]