| description abstract | Metal forming press is one of the most commonly used manufacturing machines. Every day, millions of parts are produced by metal forming ranging from battery caps to automotive body panels. Therefore, even a small improvement may add to significant corporative gain. Currently, the metal forming presses can be divided into two categories: mechanical presses and hydraulic presses. The former is fast (high speed presses may reach up to several thousand shots per minute) and energy efficient (the large flywheel eases the impulsive force), but lacks flexibility. On the other hand, the hydraulic presses are flexible (their motions can be programmed) and accurate, but are expensive to build and to operate. Recently, there are mechanical presses driven by servomotors. They could perform as flexible as hydraulic presses with high speed. Nevertheless, they are even more expensive to build and to operate. This paper introduces a new design of mechanical press whose performances are programmable, including the trajectory and the velocity of the stroke, and yet, it is relatively inexpensive to build and to operate. The key idea of the new design is a 2-degree-of-freedom seven-bar linkage mechanism driven by a large constant speed motor and a small servomotor. First, the kinetics and kinematics of the design are presented including the feasibility conditions, mechanical advantage, as well as the torque and power distribution between the two motors. Next, a number of simulation results are given. The design (parameter) optimization is also carried out using Genetic Algorithm (GA). Based on computer simulation, it is shown that the new design is indeed very attractive. | |
