Communication Dans Un Congrès Année : 2015

Multi-stage hot forming process of shackles

Résumé

This study deals with the multi-stage forming process of a sling shackle, investigated with the use of finite element simulation. Used as a lifting connector during Floating Production Unit assembly and provision of supplies for petroleum platforms, Wide Body (WB) shackles endure severe working conditions in hostile environment. Providing high level of strength and toughness as well as outstanding fatigue behavior, hot forming is one of the main production method of shackles. Aiming towards process improvement and stronger shackles development, the main purpose of this study is, with the help of numerical simulation, to understand, predict and control all aspects that can be involved in the manufacturing of a WB 125 tons shackle. In close collaboration with forging industry Le Béon Manufacturing in Lorient area, forging experiments were carried out on a 0.3MJ friction drive screw press and at temperatures higher than 900°C. In order to form both jaws, two successive sequences of closed-die forging and deflashing are performed. It follows an open-die forging stage to form the body. Finally, the crown is obtained using a ram bending process. The numerical model presented herein is developed using a fully coupled 3D thermomechanical analysis and is conducted on Abaqus software. Tools are made of AISI H13 with constant thermophysical properties. Mechanical properties of the 34CrNiMo6 used for the workpiece at temperatures ranging from 900to 1200°C and strain rates ranging from 0.1 to 1/s were extracted from the literature. To describe the compression behavior, the Johnson-Cook flow stress model has been used. Temperatures, duration and kinematic movements have been recorded over the production of 80shackles, and forging loads were evaluated by instrumenting strain gauges directly on the mechanical press. A particular methodology has been developed to perform successively the numerical simulation of the various forming operations with a unique workpiece. It combines a sequence of Abaqus/Implicit-HT, Abaqus/Dynamic-Explicit and Abaqus/Static-Implicit. In all simulations, convective and radiative cooling is taken into account and heat transfer between the tools and the workpiece is considered. As in the industrial process, workpiece stability and forging accuracy are obtained with the use of a manipulator modeled as an analytical rigid surface and a combination of springs to account for the recoil and shock absorption. A remeshing method has also been developed to thwart excessive distortion in the flash and the body.

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Dates et versions

hal-03446140 , version 1 (24-11-2021)

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Identifiants

  • HAL Id : hal-03446140 , version 1

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Julien Cochet, Sandrine Thuillier, Pierre-Yves Manach, Nicolas Decultot. Multi-stage hot forming process of shackles. CFM 2015 - 22ème Congrès Français de Mécanique, Aug 2015, Lyon, France. ⟨hal-03446140⟩
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