Simulation of a hydraulic short-stroke device for deep drawing

Abstract

A novel hydraulic short-stroke device for the deep drawing of cylindrical cups has been designed, fabricated and experiments conducted with it recently. This device reduces the cycle-time and the stroke needed by 50 percent, and also applies automatically a blank-holder force that is approximately proportional to the draw force. Wrinkle-free cups of aluminium, copper and brass of diameter 100 mm and thickness between 0.8 and 1.0 mm were drawn successfully with this device at a draw ratio of 1.85. A software was developed for simulating this process, its features being presented and discussed in this paper. The software presents the user with several windows (on a Macintosh Computer) containing text, theoretical derivations, diagrams, animation of the process, and provision for the user to interact by feeding process parameters of different values, these parameters including the draw ration, the thickness of the cup, material properties, various constants, etc. After imputting the parameters, the user can calculate various related quantities including the draw force, the blank-holding force, the fluid pressure, etc. at any value of the punch stroke. These forces and the fluid pressure are presented to the user in graphical form also. Thus,the software can be used to enable through study and understanding of the process and to select the various parameters in the design of such a device for drawing cyclindrical cups of desired specifications.