Research On The Melt-cast Explosives Quality Under Solidification Processes

Explosive casting is a kind of molding technology. In this way explosive is heated and injected into projectile or mould, after a while, solidified into a certain shape, size of explosive column. Explosive casting process involves many complicated physical changes, such as state changes, temperature changes and volume changes, this process can determine the casting quality characteristic at a large extent and accordingly affect the performance. To effectively control the solidification sequence, optimize the solidification process is the key to solve the problem of the explosive column defect.In order to study the effect of solidification process on the quality characteristic of explosive column, the solidification process of explosive was calculated by the finite element method.By analyzing some factors who influence the quality of explosive column, the influence of casting temperature, velocity, ambient temperature, heat transfer on phase change of explosive casting is studied, and optimum scheme is presented. The results show that it is advisable to set the pouring temperature to the minimum degree who ensure explosive full of projectile. Increasing velocity will cause a turbulent flow and form bubbles. Reducing ambient temperature can accelerate solidification rate of explosives surface and form shrinkage porosity. Lower heat transfer coefficient can decrease temperature gradient in explosives and is good for stress. Optimized parameters have a distinct effect on improving the comprehensive quality of explosive column, but cannot comb-out macroscopic shrinkage porosity.Based on the above, heater processing was designed and calculated. In heater processing, the solidification rate of explosives in the riser neck and below of riser neck are lower relative to the conventional process, so that, liquid explosives in the riser can fully to supplement of shrinkage porosity center.Solidification process of explosive under graded casting was calculated, the characteristics of solid liquid interface change, temperature field change and the formation characteristics of shrinkage porosity were predicted by the finite element method. The results show that, temperature field and solidification layer presenting funnel shape transits from the bottom up, shrinkage porosity in the explosive column can be completely eliminated.Above all, the research on the inherent relation between factors and the quality of explosive column and two kinds of advanced explosive casting process were provided in this paper. These works offer potent theoretical support and technical guidance for technology improvement of the explosive molding.