four-column hydraulic press中调速阀的主要性能要求有以下几点：
1. The pressure difference between the inlet and outlet of the oil cavity is that the knuckles are fully opened. When the nominal flow rate is passed, the pressure difference between the valve and the oil cavity is generally about 1mpa. If the pressure difference is too low, the pressure reducing valve cannot compensate the pressure of the throttle valve, thus affecting the stability of the flow.
2、流量调节范围，一般情况下液压机流量调节范围越大越好，并且调节时，流量变化均匀，调节性能好。
3. Stable flow refers to the flow that the speed control valve can work normally, that is, the rate of change of the flow is not more than 10%, and there is no disconnection. QF type speed regulating valve and QDF type one-way throttle valve stable flow, generally about 10% of the nominal flow.
4. Internal leakage refers to the flow rate from the oil inlet cavity to the oil outlet cavity from the clearance between the valve core and the valve body when the throttle valve is fully closed and the oil inlet cavity pressure is adjusted to the nominal pressure. The internal leakage is required to be small. In addition, when the hydraulic press is working, the speed control valve is not easy to block. The flow through the valve is less affected by temperature.