Ing. Radek Havlíček, Ph.D.

When designing a machine tool, it is necessary to start from desired machine output parameters. It is advisable to check the dynamic behaviour of the machine tool before making constructional design. By dynamic behaviour of the machine, we mean determining the time flow of trajectories, velocities, or accelerations, and arisen forces and torques of individual output working parts of the machine tool. We assume that dynamic behaviour will be assessed using a suitably built machine tool model, which describes the machine tool itself as closely as possible. The model then can by described by system of motion equations, which we solve numerically using Matlab. Based on the results calculated, we asses the most often generated inappropriate vibrations of individual machine parts. By simulating input parameters, or respectively, by change of structure, we try to minimize such vibrations. The described procedure is demonstrated by an example of a lifting unit design.

In this article, mechanical vibrations of the most strained back radial slide bearing (i. e. on the electromotor shaft outlet side) of working engine driving synchronous motor are numerically solved. For the solution, a mechanical system model was built and electromotor shaft deflections in two planes during the motor start-up were solved using Matlab. Slide lubricant was simulated using a set of elastic and dampening elements. Valued of lubricant absorption and elasticity were defined for dampening vibrations during start-up.

In the domain of mechanical vibration research, dynamic absorbers have extensive application in reducing vibrations of mechanical systems. In paper, the linear dynamics of two degree of freedom vibration mechanical system with linear damping and linear spring is studied. The system consists of the main mass and the absorber. The concept of the vibration absorber is that we want to reduce the motion of the main mass to zero. To do this, first let us modify the linear system with one degree of freedom to make it a two degree of freedom linear system. Optimum working conditions for the absorber are by the same frequencies of the action force and main mass. The effects of different parameters of the linear systems are studied numerically with Matlab.

Designing of non-cascade control of a complex electromotor-driven mechanical system respecting all parameters of individual elements is not an easy task. Degree reduction is the solution. This reduction should preserve the system dynamics. At the same time, the unstable part of the system must not be lost. Individual system states must be sorted out with respect to energy or information they contribute to the system output. The reduced system will then be used for controller design.

Designing of non-cascade control of a complex electromotor-driven mechanical system respecting all parameters of individual elements is not an easy task. Degree reduction is the solution. This reduction should preserve the system dynamics. At the same time, the unstable part of the system must not be lost. Individual system states must be sorted out with respect to energy or information they contribute to the system output. The reduced system will then be used for regulator design.

Numerické modelování umožňuje provést simulaci, popř. optimalizaci různých provozních stavů a dle výsledků simulace navrhnout úpravu konstrukce stroje. Model stroje ( skládající se z asynchronního motoru (hnací moment Mh ), hřídele (součinitel tuhosti k a tlumení b), převodovky (převodový poměr i) a výstupní částí , na kterou působí různé zatěžující momenty Mz je popsán pohybovými rovnicemi. Tyto jsou pak řešeny numericky pomocí Matlabu.

Undesirable vibration of machines and their parts can be reduced by adjusting the design, i.e. changing the vibratory system, which changes the relationship between stiffness and masses of different parts of a machine, or the introduction into the current design of other parts. Reducing adverse change vibratory oscillation system can connect in the case of a machine absorber. The principle of the use of absorber, the resonant oscillations eliminator will be shown on the simplified vibratory system without control, solved numerically using Matlab.

Machine vibrations are caused by unbalanced rotating machine parts, or operating impact load which results in the occurrence of mounting clearance, which may subsequently cause even a breakdown of the machine. Therefore it is recommended to place the individual machine parts on damping elements which would minimize these undesirable vibrations. The article features a numerical solution of an appropriate mounting of a vibrating mass using the Matlab-Simulink program.

The paper will shows method and a numerical solution of manufacturing system driving with asynchronous motor by dynamically load. The computer system Matlab - Simulink uses a numerical solution in order to solve the mathematical model, i.e. the system of non-linear differential equations of the second order.

Článek se zabývá numerickým modelováním vibrujících strojních součástí v Matlabu a na příkladu je řešení vysvětleno.

The design consists in assembling a model of the machine assuming that elastic mounting has been provided for, describing the model using equations of motion and elaborating their numerical solution. The air pressure in the air springs can be regulated according to deflections of the individual machine parts measured by accelerometers using a control element. The numeric solution provides for determination of values of stiffness coefficients k and damping coefficients c which would be optimal for the specified machine parameters in order to minimise the deflections of the individual machine parts.

The aim of the paper is to acquaint the order with design of the incorporated absorber to the vibration of generator, which makes possible the reduction of the vibration of the generator to a minimum. If we use the pneumatic spring with the changed coefficient of elasticity k with the possibility of regulation of the pressure p for the air in the operated spring in dependence to the displacement x1 of generator of is possible to reduce this displacement x1 on the minimum.