Fracturing and Deformation Characteristics of Aluminium Preform during Cold Forging at Low Strain Rates
The industrial processing of sintered powder preform has been developed for manufacturing various engineering components. The present investigation has been undertaken to analyze the deformation characteristics during the cold forging of sintered aluminium preform at low strain rates. Experiments have been conducted and measurements made on deformation during cold forging on aluminium preforms with lubricated end conditions. Experimentally obtained flow load and plastic work done are in good agreement with theoretical estimates.
High Speed Forging of Solid Powder Polygonal Discs with Bulging
The paper reports on an investigation into the various technological aspects of a high speed forging of solid powder polygonal disc which have been compacted and sintered from atomized powder. During forging, both the bulging of sides and barreling along the thickness take place. Here solution is given for forging of an N-sided polygonal sintered disc between two flat dies at high speed, taking into account the bulging of preform. An attempt has been made for the development of a generalized solution for the polygonal disc and determination of the die pressures developed during the cold forging of square sintered powder preform by using an upper bound approach. The results so obtained are discussed critically to illustrate the interaction of various process parameters involved and are presented graphically.
Investigation of dynamic effects during cold upset-forging of sintered aluminium truncated conical preforms
Abstract The present paper deals with the upper bound analysis, experimental investigation and computer simulation of upset-forging of sintered aluminium truncated conical preforms, which considers heterogeneous deformation due to barreling of preform slant sides, composite die–workpiece interfacial friction conditions, preform densification along with compression and inertia effects. A generalized theoretical expression for average forging load and preform bulged profile based on the exponential velocity field and strain rate has been established. The upset-forging experiments were conducted using the sintered preforms prepared by compacting aluminium metal powder in the closed dies and various deformation characteristics were measured. Finally, the computer simulation of the upset-forging of the sintered aluminium truncated conical preforms was performed using DEFORM software and the deformation behavior velocity, effective strain and effective stress distribution were critically studied. The effect of die speed, i.e. dynamic effects on average die load has been investigated using energy and load factors. The DOE (Design of Experiment) and RSM (Response Surface Methodology) techniques were also used to investigate and determine interrelationships between important upset-forging characteristics and the results were presented graphically. During the present investigations, it was found that inertia energy dissipation and energy factor increases, where as die load and load factor decreases exponentially with die speed. It is expected that the present work will be useful for effective assessment of various deformation characteristics during processing of sintered materials, especially at high-speed.