This paper aims to analyze the flow characteristics and fluid torques in a direct drive rotary control valve with a novel structure, and based on the computational fluid dynamics method, the advantages of improved structure are verified. With the establishment of the valve structure and the simulation model, the sliding mesh model and moving region grid are applied to simulate the complete opening and closing process of the valve at dynamic conditions. The results present that the fluid torques generate resistance torques during the increasing process of flow area while providing driving torques in the decreasing period of flow area, which is consistent with the theoretical analysis. In addition, the flow regulation of the fluid chamber is conducted with the computational fluid dynamics method and experimental test, which exhibited disagreement due to the oil leakage phenomenon. The simulation results and experimental results both convince the pressure and flow characteristics, and the improved valve model shows decreased fluid torques of around 17% compared with the original one under the system pressure of 6 MPa.

This paper is aimed at the solution of the driving actuator of the reversing valve, which is the core component of CNC die forging hammer. The proposed electromagnetic drive method contributes to a precise control of the valve spool position and eliminates the transmission mechanism and hydraulic circuits. The complete structure and the topology structure of the electromagnetic part are designed to guarantee its high controllability and robustness. The structure parameters of the electromagnetic part are calculated based on the driving requirement of the reversing valve. With the finite element analysis of the direct driving part, saturation phenomenon of the magnetic circuit is eliminated and optimization of the output force ripple is performed. The output force of the electromagnetic part is simulated to reach 1000 N with a rated speed of 0.55 m/s, which satisfies the drive demand of the reversing valve spool and the ripple amplitude of the output force is reduced by 43.9%. The operational test of the electromagnetic direct drive component is conducted to verify the finite element method simulation method and shows an expected performance.

This article proposes a servo control strategy for compensating matched and mismatched perturbations in flexible ball screw feed systems to improve their tracking performance. The perturbations that satisfy or dissatisfy the matching conditions include external disturbances, parameter uncertainties, and unmodeled dynamics. The flexible ball screw feed model includes both a rigid body and first-order axial structural dynamics. A generalized extended state observer is adopted to observe the matched and mismatched perturbations and various state variables of the system, and an improved integral sliding mode controller is proposed that can simultaneously compensate for the perturbations of the system that satisfy and dissatisfy the matching conditions. In addition, vibration compensation is designed for first-order axial vibration of the system to develop a controller that can quickly and accurately track the ideal reference trajectory, suppress system structural vibrations, and be robust to time-varying uncertainties and external disturbances. Finally, the tracking performance, anti-interference performance, and vibration suppression performance of the designed controller are verified via simulation and comparative experiments.

As the core component of the hydraulic die forging hammer, the main reversing valve controls the strike and return action of the hammer. It has high cost and poor stability since driven by hydraulic pressure, which needs a separately hydraulic circuit and it is unable to control the valve core precisely. In order to improve the speed control accuracy and position precision, a new drive method based on TPMLM (tubular permanent magnet linear motor) is designed in this paper. The mathematical models of the original reversing valve and the improved one are built. Theoretical calculation and simulation on the fluid force analysis are discussed to verify the method. The simulation performance is conduct to compare response characteristic between the two hydraulic systems based on AMESim. The results indicate that the new drive method exhibits a faster response of the reversing valve.