Classification of hydraulic control system of four-column Hydraulic Press
There are many classification methods for the hydraulic control system of a four-column hydraulic press. China Machinery Co., Ltd. only focuses on two commonly used classification methods.
According to the physical dimension of the output of the hydraulic control system, it can be divided into three types: hydraulic position control system, hydraulic speed control system and hydraulic force control system.
Four-column hydraulic press hydraulic force control system
The full force, torque or pressure of the output disk of the Tathagata hydraulic control system is called the pressure exerted control system. It is a schematic diagram of a planting pressure force control system. The force object is an object with a certain mass and elasticity, one end is fixed with the platform, and the other end is connected with the piston rod of the forcing hydraulic cylinder. In order to measure the magnitude of the applied force, a force sensor is also connected between the force-bearing object and the piston. The hydraulic cylinder is directly equipped with an electro-hydraulic servo valve, which is communicated with each other through a channel. When a voltage signal Vo is given, it is corrected and amplified and then input into the control coil of the electro-hydraulic servo valve. Therefore, a certain amount of flow will enter one cavity of the forcing hydraulic cylinder, and the other cavity will have the same flow through the servo The valve returns to the tank, so the piston of the hydraulic cylinder will move to overcome the elastic deformation of the object. Since there is a certain hydraulic pressure acting on the force-applying piston, the force applied to the force-bearing object is the output of the hydraulic force control system. The force sensor feels this force, and it forms a force-to-electrical converter together with the carrier amplifier, which converts the sensed force into a voltage signal and inputs it into the system in the form of negative feedback. Obviously, the applied force F is proportional to the given voltage signal Vo.
is a pressure control system. The test piece needs to apply a functional force F, which is given by the press. Obviously, the hydraulic pressure PL in the lower cavity of the press must also be a proportional function of time, so it needs to be controlled. The-cavity of the electro-hydraulic servo valve is blocked to form a blind cavity, and the other cavity is communicated with the press. The given electrical signal Vo is integrated and amplified and then sent to the servo valve. The servo valve fills the lower cavity of the press with a corresponding flow rate. When a certain amount of drift effect is overcome, the pressure in the press cavity rises sharply. The pressure sensor and the carrier amplifier form a pressure-voltage converter, which converts the pressure in the lower cavity of the press into a voltage multiplier v, and inputs it into the system in the form of negative feedback. When v=Vo, it indicates that the pressure of the liquid in the lower cavity of the press has reached the required value, so the current output by the integrating amplifier remains unchanged, so the flow rate output by the servo valve remains unchanged, and the system is balanced. At this time, the flow delivered by the servo valve to the compressor is required for the upward movement of the piston of the compressor. The purpose of using the integrating amplifier here is to reduce the static error of the system, which will be described in detail in the later chapters of this book. The pressure accumulator in the solid 1-6 is used to supplement the flow that is needed instantaneously but cannot be satisfied by a single stable volume pump.
Hydraulic position control system, hydraulic speed control system and hydraulic force control system can sometimes be referred to as position system, speed system and force system (or force system) respectively.
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