Jaroslav Beran

Magnetic-mechanical accumulator of kinetic energy

Abstract The paper focuses on the process of non-contacting kinetic energy accumulation at the dead-end positions of a reciprocating rectilinear motion with a variable stroke. It describes the development of a magnetic-mechanical accumulator that absorbs energy while the moving part is decelerating towards the dead-end position and releases the energy back to the system while it is accelerating from the dead-end position. At the same time, it enables stroke modification of a certain level with a minimal impact on the maximum force of the accumulator. With respect to the magneto-static analysis of components, the preload of the mechanical element has been set accordingly. The dynamic analysis of the system has been carried out and the prototype produced and tested on the testing rig.

Design of Coaxial Needleless Electrospinning Electrode with Respect to the Distribution of Electric Field

The paper is focused on the design of the electrode for needleless coaxial electrospinning. This method allows to produce core/shell nanofibers from the free surface of a polymeric two-layer. The geometry of the designed model of electrode was analyzed using the software Autodesk Simulation Multiphysics. The results of electrostatic field simulation indicate the sharp edges of the electrode as the source of high electric intensity. These sharp edges lead to the loss of the electric energy during the electrospinning process. Based on that, the new cylindrical geometry of the electrode was developed. The results of carried out experiments clearly demonstrate the enhancement of the electrospinning process stability.

Dynamic Properties of Traversing Rod

The paper deals with an analysis of traversing rod dynamic properties. The traversing rod is a part of winding mechanisms on rotor spinning machines, and transmits periodical linear traversing motion from motor to yarn guides. The rod is specific by its very thin and long shape where the ratio between length and diameter reaches almost 4,000:1. Due to a demanding exciting motion it is subject of high dynamic load resulting in mainly longitudinal vibrations. In order to better understand the behaviour of the system, several measurements of material and dynamic properties of the rod were carried out. Moreover a mathematical model of the rod was created and loaded by the requested motion. The performed analysis disclosed new information about the dynamic behaviour of the rod. However, the results confirmed the assumptions that the rod poses limiting factor in reaching high speeds.

Enhanced Central System Of The Traversing Rod For High-Performance Rotor Spinning Machines

Abstract The paper deals with the improvement of central traversing system on rotor spinning machines, where rectilinear motion with variable stroke is used. A new system of traversing rod with implemented set of magnetic-mechanical energy accumulators is described. Mathematical model of this system is analysed in the MSC. Software Adams/View and verified by an experimental measurement on a real-length testing rig. Analysis results prove the enhancement of devised traversing system, where the overall dynamic force is reduced considerably. At the same time, the precision of the traversing movement over the machine length is increased. This enables to increase machine operating speed while satisfying both the maximal tensile strength of the traversing rod and also output bobbin size standards. The usage of the developed mathematical model for determination of the optimal number and distribution of accumulators over the traversing rod of optional parameters is proved. The potential of the devised system for high-performance rotor spinning machines with longer traversing rod is also discussed.

Approach To Analyse Of Reaction Forces In Ring–Traveller System

Abstract The paper presents the approach to analyse of reaction forces and contact pressure for ring-traveller system in twisting machine. The theory of the ballooning yarn has been adapted for the calculation of reactions, and the motion equation is developed for traveller with two reaction forces. The components of normal reaction forces are analyzed for system with free balloon and control one. The effect of the balloon control ring is shown to be significant, reducing the reaction forces of traveller or increasing the speed of spindle. Contact pressure generated between the ring and the traveller is analyzed using Hertzian contact theory. The article also presents the recommendations for optimization of the traveller shape to increase its service life.

Protrusion of the Rod Electrode in the Electrospinning Process

The paper focuses on the influence of the protrusion of the rod electrode on critical voltage in the DC electrospinning process. On the testing and industrial DC electrospinning devices, electrodes of any kind are extended towards the counter electrode. This provides the maximal, that is, supercritical, electric field intensity on the spinning-electrode orifice that is found to be higher than on the other supplementary parts. The principal study and experiments with basic apparatus were carried out and presented by Taylor in 1966. This study is focused on the arrangement closely related to the design of the real electrospinning device with respect to the safety and technological aspects. Results of the carried out experiments of the rod spinning-electrode are compared with the electrostatic simulation and analytical calculation. The presented effect of the electrode protrusion on the potential difference and the critical field strength introduces valuable information for the designers of electrospinning machines as well as for the setting up of the optimal technological parameters for producing modern nonwoven textile products.