The Evolution Process Of Billet With Twin Nozzles In Multi-spray Forming And Shape Control

In multi-spray forming, twin nozzles can be used simultaneously to spray large size billets and to increase throughput. The advantage is better control of the distribution of the melted metal and enthalpy fluxed on the deposit surface. Therefore the billet preparation with twin nozzles in multi-spray forming is the direction for spray forming industry development.The arrangement structure of the twin spray nozzles is studied, the growth rule of deposit formation has been analyzed, and a model for simulating billet of the spray forming has been developed. The evolution process of the preform with time can be described by the model of deposition. The 3D model, which allows the nozzles to be placed asymmetrically over the substrate was developed. This makes it possible to model not only the growth of a Gaussian shaped preform, in which case the spray axis and the rotation axis coincide, but also the surface evolution during billet growth. The model is able to predict the shape of billet, analysis the spray mass flow rate along the axis in the spray cone and the shading effect.The influence of principal spray forming parameters of billet deposition on geometry and process have been studied, such as the withdrawal speed of the growing billet, the rotation speed of the substrate, the flow rate of the alloy melt, the mode of nozzle scanning and scanning angle, and the eccentricity of nozzle.Application of intelligent control technology in spray forming is studied. The monitor system of spray forming has been proposed, and the real-time control of the entire process can be realized. The billet with destination diameter and flat surface can be gotten with the real-time size detection and feed-back control technology.By mass experimental studies with single and twin spray nozzles in multi-spray forming, the experimental results indicated that the stimulations of the mathematical model of billet are in good agreement with the experimental results.This research result has been succeeded applied in billet spray forming equipment of SFZD500, and billet products with diameter 400mm, height 1.5m have been stably produced.