Edward Lisowski

The paper presents an analysis of switching time for pilot operated directional control valve [1–3] in a typical hydraulic system, in which the actuator is a hydraulic cylinder. A mathematical model has been built which contains equations of motion for the valve and actuator components, the balance of fluid flow, flow through the gap, and the principle of conservation of momentum and the flow curves of pressure relief valves [6, 8]. The system of equations is solved by fourthorder Runge-Kutta method. A survey to find minimal switching time has been conducted [4]. Positive overlap value, the coefficient of its movement resistance and control pressure value have significant impact on the switching time in the tested valve.

In the paper an analysis of gripping thin metal sheets in technological process of stamping metal closures is presented. An object made of two suction cups and pneumatic control system of vacuum and pressure inside the suction cup was analyzed. Mathematical model contains differential equations which were solved basing on Matlab/Simulink application. Prepared model provides an opportunity to check different parameters of the system. The paper presents analysis of impact of feed pressure on the course of sucking forces.

This paper presents methods for automatic generation of 3D models of hydraulic components. For the purposes of generating models the authors’ own software and PTC Creo Parametric CAD system was used.

The paper presents a CFD analysis of flow forces acting on a spool of directional control valve type WE10J. This is a four-port, three-position, solenoid directly operated valve with a nominal diameter of 10 mm and working pressure up to 35 MPa. The aim of the study was to investigate whether hydraulic forces acting on the spool during the flow of working fluid through the valve could be reduced by changing the geometry of that spool. ANSYS/Fluent software was used for the CFD analysis.

The article presents the evaluation of possibility of pressure losses reduction at the flow through a WEH22 hydraulic directional control valve. For this purpose, 3D models of flow paths were built using the Creo Parametric software. Then the models were used in the ANSYS/Fluent software to calculate pressure losses. The results of the analysis have allowed for determination of possibilities of pressure losses reduction without changing overall dimensions of the valve body.

This paper presents a method with the use of CFD analysis for calculating the forces acting on the spool during the flow of working liquid stream through the electro-hydraulic pilot operated directional control valve. The liquid stream flowing through the directional valve causes hydrodynamic response according to the principle of conservation of momentum. Liquid pressure acting on the spool surface affects the forces balance of valve spool as well. An object of the research is the pilot operated directional control valve WEH22 type with flow rate up to 450 dm3/min. For the analysis ANSYS/Fluent software was used.

The paper presents a method of optimizing the geometry of a cycloid positive displacement pump using genetic algorithm. This allowed for increasing its delivery and efficiency and reduce pulsation.

In the paper an analysis and investigation of round metal sheet sharing force and crown cork drawing force are presented. Experimental test stand was created in order to perform analysis on sharing and drawing forces for several metal sheet thicknesses. Obtained results are sufficient for comparison of acting forces for different metal sheet thicknesses and hardness during cutting process.

The paper presents the results of research on minimizing the air consumption of the air cushions used to move the transport platform. This kind of transport becomes more popular in industry. It is applied especially to move heavy machinery and equipment in factories with hardened floors. The working medium is air. This system has many advantages but it is characterized by high air consumption. The paper takes the issues of searching solutions to minimizing the air consumption. To perform the computational analysis a mathematical model was defined. Simulations were performed by using Maple software.

The paper presents the results of research for load lifting process for a single pneumatic cushion. The load lifting process has been simulated in SolidWorks Simulation using the model of Mooney-Rivlin for hyperelastic material. Research was conducted based on a simplified 3D model and drawn up a mathematical model of pneumatic cushions determining of non-linear static characteristics for the lifting height depending on the weight of the load and supply pressure. The results compare with the results of laboratory tests conducted for the platform equipped with four air cushions.

In this paper, a simulation and an experimental analysis of upsetting a cold ring placed between two rigid plates were conducted. When designing a new process, it is preferable to carry out the simulation studies using FEM, which allow for the prediction of the course and proper selection of process conditions. Due to the complexity of phenomena that occur during plastic formation, it is essential to have a good description of contact phenomena and properties of material in the plastic state. The computer simulation was performed for a specific material – a thick plate of hot-rolled carbon steel with fixed initial dimensions of rings and different values of the coefficient of friction.

The paper presents the effect of air suspension system on semi-trailers during loading and unloading processes while using a forklift. The mathematical model was created, which takes into account a sharp loading on the rear platform of a semi-trailer. The entry of a loaded forklift onto the rear platform of a semi-trailer causes rapid lowering of the platform, which contributes to an unstable movement of the forklift.