Improvement of the Design of Rocket Propelled Granite (RPG.7) Main Tube’s Forging Dies

Abstract

A lot of engineering design studies concerned with modifying or improving of the already existing products, rather than searching for producing anew products. This study put full attention to improve or modify the design of the hot-forging dies which produce the main forged tube for the launcher RPG7. The research started with the study of the existing design ( old design ) by determining its advantages and disadvantages, and then the detail studies for the forging dies continued with considerations for all forging stages of dies and related hard production environment and situations such as severe mechanical and thermal stresses.This reflected directly on the selection of material and its heat-treatment, and further on the method or procedure of die making with respect to the available machines, equipments, tool, and required specifications . The study produced a new design for the hot-forging dies which include the set of hammering dies and the set of trimming dies, which co-operated together to produce the forged tube, as suggested by the new design that avoided many disadvantages of the old designed forged tube, mainly the difficulties of machining the forged tube, the great amount of losses in raw material, and the shortage in die-life of hammering dies. All the new designs carried out by using the computer, the Vero International Software VISI 12.1 in the stage of CAD (Computer-Aided Design) and the software NX3 in the stage of CAM (Computer-Aided Manufacturing). The new design achieved the following improvements:  Reduction of processes by eliminating some of machining processes that used to be taken before rough turning to remove sharp and hard edges of the semi-tripezoidal section of old forged tube.  Facilitation the process of rough turning in lathe machine by chosen of cylinderical profile.This minimized the machine vibration and elongated the life-time of the cutting tool.  Saving in raw material by about 5 Kg per piece, thus results in a saving of a minimum of 20000 $ (twenty thousand dollars) per year.  Elongation of the life-time of hammering dies by avoiding the deep impressions due to the parting line’s location.  Localization of forging die’s designing and manufacturing which results in saving of a tens of thousands of dollars per year