An approach to simulate cold roll-forging of turbo-engine thin compressor blade M. Sedighi and M. Mahmoodi School of Mechanical Engineering, University of Science and Technology, Tehran, Iran Abstract Purpose – Studying manufacturing process of compressor blade can reduce the production cost and time in aircraft turbo-engine industries. In the cold roll-forging of thin compressor blades, the elastic behavior of machine structure and rolls is considerable due to the higher volume of roll separating force. Owing to this kind of elastic deformation during rolling, the adjusted gap between the rolling dies is increased and this causes unexpected flow of material, shape and thickness. The purpose of this paper is to present a new approach for simulation of cold rolling of thin blades and studying the effect of elastic behavior of the machine structure as well as rolls deflection on the material flow and roll separating force. Design/methodology/approach – In this paper, the process has been investigated using experimental test and simulation by introducing a new approach in a decision-making flowchart. Instead of simulating of the entire system structure, a couple of virtual deformable rolls are suggested. The specifications of these rolls are selected to behave elastically during rolling same as whole roll stand. In addition, the thickness values are compared in both experiment and simulation. Also, the roll separating force is compared with and without using this approach. Findings – A decision-making algorithm has been presented that can be used to study the process. This finding provides the basis to investigate the effect of elastic deformation of machine structure and rolls on dimensional accuracy and roll force. Originality/value – Result of this work can promote the position of simulation of the thin rolled sections to an extent more compatible with reality. For instance, the amount of increased gap between two dies during rolling can be estimated accurately. Also the influence of this gap on final blade thickness and the roll force and on the roll torque can be investigated by this approach. Keywords Simulation, Compressors, Elastic analysis, Production metallurgy, Alloys Paper type Research paper Nomenclature d ¼ roll deflection L ¼ roll length I ¼ moment of inertia D ¼ roll diameter E ¼ modulus of elasticity m ¼ friction coefficient P ¼ force Dh ¼ thickness reduction 1. Introduction Cold rolling is one of the methods used for the production of compressor blades to eliminate machining and grinding operations. In this method, a blank is rolled between two rolls with a shaped tool (die) which have been fixed on them in the direction from the blade’s root to its tip. Cold rolling can produce a blade with a higher mechanical property and a higher accuracy and surface finish. In any study of blade rolling, it is usually required to reduce the number of passes considering the desirable material flow and created cold-work and stresses. So, this can reduce the number of intermediate heat treatment and the production time and cost. The above- mentioned points are under the impact of another factor such as the elastic behavior of the machine structure, which is due to the high amount of roll separating force. Also in the study of material flow, besides the initial geometrical specifications and materials properties, the opening of the gap between two dies shall be considered. Cold rolling of blades has been attracted some researchers. Their researches first include studying of the die and preform design considering the material workability. Then simulation- aided trial and error has been employed. Furthermore, by applying finite element software, some specification of the process same as roll deflection and roll pass design has been studied. Matviichuk et al. (1992) analyzed blade rolling based on the workability analysis of the blank. Process simulation provides the virtual trial and error environment that can predict forming, under-fills, microstructure, mill load and roll deflection. Making use of finite element method (FEM) and applying experimental data and simulation, Saigal and Mantri (2004) improved the pinch and roll process to reduce the number of roll passes. Akgerman et al. (1980) proceeded to simulate rolling blade sections using two ROLPAS and SHPROL computer programs. In simulation of shape rolling, Capece Minutolo et al. (2006) used rigid surfaces for the rolls and studied the dimensional analysis of the suitable sections for different passes and material flow during hot rolling process. In cold rolling process, increased gap between two rolls is due to the rolls deflection and the elastic or spring behavior of the other parts of the structure. It is safe to say that the value of elastic deformation during rolling depends on the machine components and their assembly method, material and required reduction considering the geometry of the part. For acquiring precise parts with closed tolerances in The current issue and full text archive of this journal is available at www.emeraldinsight.com/1748-8842.htm Aircraft Engineering and Aerospace Technology: An International Journal 81/3 (2009) 191–198 q Emerald Group Publishing Limited [ISSN 1748-8842] [DOI 10.1108/00022660910954682] 191