Showing papers by "Shiro Kobayashi published in 1995"

Process sequence design in cold extrusion to form an axisymmetric shell body

Abstract: The multi-stage cold extrusion process to produce a steel axisymmetric shell body is investigated for process sequence design by using the finite element method. The main design goal is to obtain the optimum process sequence which can produce the required part most economically. The established process sequence is simulated and design criteria are examined. Based on the results of preliminary simulation, two strategies for improving the sequence are derived for the type of preform. Using the approach taken with a plate preform, the finished product of a shell body is produced in three operations and two annealing treatments while the conventional sequence consists of five forming operations and four annealing treatments. The final design of the improved sequence is achieved by controlling process parameters and through creative punch design based on the finite element simulations.

Superplastic forging design of a jet engine disk by the finite element method

Abstract: Process design in superplastic bulk forming to produce a nickel-base jet engine disk has been carried out using the rigid-viscoplastic finite element method. This study aims at deriving systematic procedures in forging of a superalloy engine disk, and develops a scheme to control strain-rate within the range of superplastic deformation during the forging operation. The new process, using a pancake-shaped perform, is designed to have less manufacturing time, and a more even distribution of effective strain in the final product, while the conventional superplastic forging of an engine disk has been produced using a cylindrical billet. The process information required for the operation using the pancake-shaped preform is obtained from numerical analysis on the conventional forging of superplasticity, and then applied to the new process design.