UBC Theses and Dissertations
Transfer die system timing and parameter optimization according to an obstacle map Han, Guanzhong
For complex sheet metal parts, multiple stamping stages are needed in a sequence. In today’s industry, intermediate parts are transferred between stages automatically by feeding as a strip (progressive die) or a blank (transfer die). Although progressive/transfer dies are highly automated, transfer system parameters need to be predefined. These parameters must ensure that the part is transferred to next stage quickly and safely. However, due to highly complex geometry and motion in the die system, these parameters are conventionally finalized manually according to designers’ experience. In this thesis, algorithms are proposed to optimize transfer system parameters in transfer die, according to the geometry and motion restrictions of the entire system. Two algorithms are proposed to complete a two-step optimization process. In the first step, the geometry of the die set and parts are analyzed. Based on Siemens NX software and customized kinematic model, motions of die components are simulated, an “Obstacle Map” is generated to record the potential collisions between parts (and grippers) and die set during the part transfer process. Obstacle map can be regarded as an inherent property of the entire die system geometry, which can be utilized not only for the optimization algorithm proposed in the second step, but also for future research. In the second step, with obstacle map, motions of the transfer system are analyzed. According to system motion capacity and freedom of modification in practice, transfer system parameters are optimized. The core of the algorithm in this step is to apply overlap between motions to reduce the transfer duration. Lift stroke and press stroke are also optimized when modifications are allowed. The optimized transfer system parameters result in improved strokes per minute, while all the obstacles in the obstacle map are bypassed. One case study for a typical transfer die system with 14 initial SPM is performed to show the effectiveness of the proposed algorithms. Four levels of optimization are conducted with increasing freedom of modification: initial speed -> maximum speed -> allow lift stroke modification -> allow press stroke modification. The results show that the proposed algorithms are valid, SPM can be improved (22.9 -> 26.52 -> 26.61 -> 27.99) in different situations. Some topics can be further addressed based on the works in this thesis, future works can focus on algorithm expansion to progressive die, and algorithm improvements for more complex cases.
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