YB32—300液压机(天津锻压机床厂产品)采用QF_1预泄换向阀保证在发出回程讯号时滑块卸压后再回程。但近年来出现了所谓“二次压力”。即在工件压制完毕发出回程讯号后,QF_1预泄换向阀开始预泄,主缸上腔压力逐渐减小,当上腔压力小于控制油路压力(1.6MPa)时,滑块本应换向回程。但是,在滑块还未动 YB32-300 hydraulic machine (Tianjin forging machine tool factory products) QF_1 pre-vent valve to ensure that when the return signal issued by the slider relief after the return trip. But in recent years there has been a so-called “secondary pressure.” That is, after the workpiece is pressed back signal is issued, QF_1 pre-vent valve to pre-vent, the master cylinder pressure on the chamber gradually decreases, when the chamber pressure is less than the control circuit pressure (1.6MPa), the slider should be reversed Return. However, the slider has not moved yet