Abstract:

The transmission efficiency of a hydraulic press fast forging is less than 5%, it causes a great waste of energy. In view of this, a new hydraulic system of accumulator with compound power producer was proposed herein, which combined a direct-driven pump of variable frequency with accumulator. In order to control the pressure of the pump output, a  fuzzy self-turning closed-loop control strategy was adopted, thus making it possible stable pressure outputs without overflow under the low installed power, and providing stable power inputs for electro-hydraulic proportional control of the hydraulic forging press. Differential circuit was applied during down-stroke stage to reduce throttling loss. The mathematic model of pump unit was founded and working parameters' calculation principles were given.The experimental results show that the position error of  the new fast forging hydraulic system is lower to 0.2mm, and the total energy consumption is reduced by 65.3% compared with the traditional electro-hydraulic proportional system. Meanwhile, the results also prove that transmission efficiency is increased by 13.4%.

Key words: hydraulic press, saving energy, variable frequency, accumulator, transmission efficiency

摘要：

针对快锻时不足5%的传动效率造成的液压传动系统高能耗问题，提出由变频直驱泵与蓄能器结合起来而构成的新型泵-蓄能器复合动力源系统，并以泵口压力为控制目标，通过模糊自整定压力闭环控制策略，实现低装机功率下动力源的无溢流稳压输出，也为锻造液压机电液比例控制系统提供了稳定的动力输入。为减少节流损失，压下时利用差动回路。建立了泵头单元的数学模型，给出了确定蓄能器工作参数的基本原则。实验研究表明，基于变频调节的快锻液压系统位置误差可达0.2mm，较电液比例阀控系统总能耗降低65.3%，传动效率提高13.4%。

关键词: 液压机, 节能, 变频, 蓄能器, 传动效率