Jun Peng Shao

Using Fuzzy Switching to Achieve the Smooth Switching of Force and Position

In order to achieve the switching function of the force and position, the force control is executed when the hydraulic cylinder contacts with the mechanical objects, the position control is executed when the hydraulic cylinder is far away from the mechanical objects. This paper respectively established force control model and position control model. The position control adopts the PID algorithm and the force control adopts the fuzzy algorithm. In order to solve the jump and jitter of the parameters when force-position switching, this paper puts forward a fuzzy switching adaptive control strategy. Fuzzy switching ensures the smooth transition of the two control models, the results of simulations show that fuzzy switching not only ensures the system’s rapidity but also shows excellent robustness against variations of system parameters and external disturbances.

Simulation on Multi-Oil-Cavity and Multi-Oil-Pad Hydrostatic Bearings

Taking multi-oil-cavity and multi-oil-pad hydrostatic bearings as studied projects, firstly make brief instructions for structure characteristics and working principal of hydraulic system; Then, build three-dimensional models of multi-oil-cavity and multi-oil-pad hydrostatic bearings respectively. Adopting finite volume method, oil film mesh is generated by universal finite analysis software CFD; then, carry on numerical simulations for pressure distribution and temperature distribution of the two studied hydrostatic thrust bearing under various viscosity, and make comparative analysis for difference between the two studied hydrostatic thrust bearing. Based on the analysis of numerical simulation results, the conclusions whether oil-return groove is set for hydrostatic bearing could be received. Simulation results reveal truly the influence of setting oil-return groove or not on hydrostatic thrust bearing, and improve structure design for hydrostatic thrust bearing.

Temperature Field of Hydrostatic Supporting Disk in Different Viscosity and Rotational Speed

With heavy hydrostatic bearing as the research object, establish oil film viscosity-temperature equation. Adopt finite volume method, respectively calculates the oil film temperature field under different rotate velocity in Invariant viscosity and variable viscosity, revealing the oil film temperature arise influence rule of hydrostatic bearing on the viscosity and rotate velocity. The results show that the viscosity and rotate velocity have a great influence on the hydrostatic bearing oil film temperature rise, but the effect regularity varied. The calculated results that provide a theoretical basis for the hydrostatic bearing structure design and bearing deformation calculation, and have very important significance on improve the reliability and precision of the whole machine tools.

Research on Hydrostatic Supporting Temperature-Rise of Heavy NC Machine Tool

With heavy NC machine tool is widely used in many oil pad round guide hydrostatic bearing as the research object, in the under condition of variable viscosity, establish oil film viscosity-temperature equation. Adopt finite volume method, simulation the hydrostatic bearing internal fluid temperature field under different flow rates on the speed of 6R / min. Numerical simulation hydrostatic thrust bearing oil film temperature field, can find a general high temperature region, and then take effective control temperature. It can achieve the hydrostatic thrust bearing oil film temperature field prediction for engineering practical oil chamber structure, offer the theoretical foundation for optimization design.

Simulation on Supporting Characteristics of Heavy Hydrostatic Thrust Bearing

The pressure field of the clearance oil film of the hydrostatic bearing in varies velocities was simulated based on Finite Volume Method (FVM) by the software of Computational Fluid Dynamics. In this article, a conclusion could be drawn that the viscosity has great influences on the pressure in the heavy hydrostatic bearing and it cannot be neglected especially in high rotating speed. The results of numerical calculations provide internal flow status inside the bearing, which would help the design of the oil cavity structure of the bearing in engineering practice.

Research on Temperature Field Distribution of Heavy Hydrostatic Thrust Bearing Rotation-Workbench at Different Rotating Velocity

Based on heat transfer theory, thermodynamics steady state equation of hydrostatic bearing, thermal mathematical model of hydrostatic bearing and boundary condition of numerical simulation is established. Temperature field distribution of hydrostatic bearing at different velocity is numerical simulated. Regularity of the influence of velocity on temperature field of heavy hydrostatic thrust bearing is revealed. The results show that, velocity impacted a significant influence on heat transfer and temperature field distribution of hydrostatic bearing. Average temperature of workbench steadily declined as velocity increasing, while average temperature of base gradually increased; both of them emerged serious heat concentration, but the cooling situation of workbench is better than base. The numerical simulation results could provide theoretical basis for temperature control scheme design which will improve the stability and reliability during hydrostatic bearing operation.

Thermal Deformation Impact Analysis on the Workbench of Large Size Hydrostatic Bearing Plate Structure

Thermal deformation of large size hydrostatic bearing rotary workbench is the most direct factor that affects the machining accuracy of work-piece. The thesis puts forward the method of adding reinforcing plate structure to restrain the workbench thermal deformation, establishes three-dimensional supporting workbench model, with finite element method and sequence of fluid-solid coupling technology have carried on the thermal deformation calculation workbench, and reveals the influence law of different installation position of rib plate on the workbench thermal deformation. The results of the study shows that the method of adding reinforcing plate structure to reduce the thermal deformation of hydrostatic bearing worktable is feasible, and determine the optimal position of reinforcing plate by comparing different results.

Modeling and Motion Control of Hydraulic Biped Robot

The foot robot has a good adaptability to terrain and hydraulic drive has a great power to weight ratio compared with other drivers, therefore, a hydraulically actuated biped robot is proposed to meet the need for the high flexibility and high load capability, and each leg has four degrees of freedom. According to the proportion of human leg, the leg mechanism of biped robot is designed .A kind of simplified structure of the hydraulic biped robot is put forward based on the analysis of the structure. The model of the leg is established by Lagrange equation to obtain the corresponding dynamic model; the model of the hydraulic system is established according to the hydraulic control theory; the whole model of the leg is obtained combined with the two models. The variable structure control is suitable for the complex high-order control system, keeps invariant for external disturbance and parameter changes, and easily implements the control algorithm on-line, so the variable structure control is used to study on the motion control of the robot. The simulation is executed in Matlab software, which verifies that the mechanical structure is reasonable and the control algorithm is effective.

Rotational Velocity Influence Research on Pressure Field of Hydrostatic Bearing with Constant Flow

Large size hydrostatic bearing is the core component of heavy CNC equipment. The influence of pressure, heating and running time can reduce film thickness during operation. This will directly affect machining accuracy and operation reliability of the entire machine. Aiming at the problem of influence of rotational velocity on carrying capacity of heavy hydrostatic bearing, use finite volume method (FVM) to simulate gap film pressure field of heavy hydrostatic bearing with Constant Flow and study pressure field distribution law on the conditions of the different rotational velocity and same cavity depth, oil cavity area, then optimize oil cavity structure. Results show that, pressure field distribution law of the different rotational velocity is basically identical, but its carrying capacity is different. From the relation curve of the pressure and rotational velocity can be seen, because of the dynamic pressure of existence, along with the increase of rotational velocity, carrying capacity gradually. The study is of vital theoretical significance for the improvement of machining accuracy of numerical control machine and the entire CNC equipment and provides valuable theoretical basis for the design of hydrostatic guide rail in engineering practice.

Oil Film Flow-State Analysis of Hydrostatic Vertical Guideway of CNC Vertical Lathe Rail Head

Hydrostatic lubricated vertical guideway is commonly used as a form of rail head bearing lubrication in CNC vertical lathe lubricated bearing. In order to improve the cutting performance of CNC equipment during machining, we have studied the hydrostatic vertical guideway with inner slide during the process of ram feed moving in this paper. The single rectangular cavity flow equation and velocity equation are derived. Numerical simulation of taking limit working conditions that the cutting force is taken byis studied by the Finite Volume Method (FVM). The flow field and velocity distribution of X direction and Y direction of hydrostatic vertical guideway are obtained by using quantitative method and supplying oil with a single chamber, with the inlet flow of 0.52L/min, with the film thickness of 0.023mm and the depth of oil cavity of . The mathematical model by theoretical derivation and the flow state regularity in limit working conditions are verified and revealed. The results of study above in this paper provide valuable theoretical basis for hydrostatic guideway design in practical projects.