‎محمود فرزين، احمد كرمانپور

1396/10/03

كتابنامه

مكانيك

مهندسي مكانيك

ID9544

به فارسي و انگليسي

Theoretical and Analytical Studies and Design of Ultrasonic Cold Forging UCF Machine for Development of Surface Nanostructure Seyed Masoud Loeian Sm loueian@me iut ac ir May 16st 2011 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Saeed Behbahani behbahani@cc iut ac ir Fathallah Karimzadeh karimzadeh f@cc iut ac ir Abstract Ultrasonic Cold Forging UCF technology enhances mechanical properties of metals by generating a nano structure layer on their surface During UCF process static and high frequency dynamic forces are applied on the surface of the work piece by a spherical rigid tool in order to cause severe plastic deformation on a thin layer of the surface The changes in the appearance and the size of the work piece due to the severe plastic deformation are negligible while developed nano structure layer with induced work hardening and residual stress improves the surface mechanical properties of the samples remarkably Design and production of a UCF machine to be mounted on commercial turning and milling machines as well as identification of the process through experimental and numerical methods are two main objectives of this research Vibratory components of the head of the UCF machine play a very important role in the appropriate amplification and concentration of the generated oscillation The shape and mounting points of these components are designed and analyzed using modal analysis and based on these design UCF machine is manufactured The fabricated machine has been employed for surface treatment of two steel samples AISI S1 and AISI 4130 Before UCF process gains of two samples have average size 20 m After applying ultrasonic impacts nano structure layer is observed with average grain size 70 nm at the edge of S1 sample and the thickness of new micro structure is 100 m It has been determined that hardness of surface increased about two times compared with the conventionally sample and hardness incensement is observed till depth 450 m Also 50 nm grain size is obtained at the edge of 4130 steel and depth of new structure is 120 m The hardness of the surfaces was increased to 400 Vickers after applying UCF process at the surface and hardness of sample increased up to depth 200 m To identify the process the severe plastic deformations along with the induced residual stresses were analyzed using finite element simulation 4 models is generated The first one is considered as the reference model and in other three models the effect of changing of the tool velocity vibration amplitude and static force is studied By increasing the ultrasonic vibration amplitude and decreasing the tool velocity equivalent plastic strain and thickness of new microstructure is enhanced Depth of residual stress for all of the simulations is 750 m The obtained results showed that the highest residual stress and the highest equivalent plastic strain were generated in the case of the highest vibration amplitude The best roughness was gained in the model that had the least static force and the minimum residual stress is monitored in the process that has the least tool velocity Key Words Ultrasonic Cold Forging Nanostructure Severe plastic deformation Surface treatment Finite Element Model Modal Analysis

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‎محمود فرزين، احمد كرمانپور