Tomáš Stejskal

Mechanism of Randomness in Vibration Signals of Machinery

The paper deals with a special analysis of the vibration signal, which may reveal the chaotic behavior of the machine. The most likely effect of randomness is an exponential distribution. In case of the time interval divisions between peaks signal from vibrating machinery process has not a unique character of exponential distribution.

The Effectiveness of a Three-Temperature Heat Pump System

Three-temperature heating systems consist of a heat engine and a heat pump, enabling thus maximum usage of the primary thermal source for the heating of buildings. This analysis has revealed obvious advantages and disadvantages that the combining of thermodynamic systems has in future development, also with respect to environmental and economic issues. It appears that the combination of a Stirling engine or a similar heat drive with a heat pump is especially suitable. In order to analyze the effectiveness of such a system, a comprehensive calculation procedure is used: its basis lies in accounting for all types of energy and their relationship to the original natural resource. The present paper aims to point out that the combination of Stirling engine and a heat pump is a useful solution thanks to the most favorable resultant economic impact if compared to the usage of a diesel, four-stroke gas, or, most commonly used, electric drive.

Production Aspects Affecting the Final Precision Machining of Advanced Materials

When creating products of modern construction materials has a great influence on their endpoints right way and the quality of working on machine tools. The article deals with positioning accuracy of machine tools which is carried out in an unloaded condition, according to international standard ISO 230-2. Overall accuracy of working machining is determined mainly static rigidity, geometrical accuracy of mechanical components, positioning accuracy and dynamic stiffness. Static stiffness is defined in new machine tools in a limited workspace. Therefore, the article deals with the definition of static stiffness in the expanded work area and also defines its impact on the positioning accuracy at individual points in workspace of the machine tool.

Impact of the Technological Conditions of Plane Surface Machining on a Triangular Milling Cutter on the Residual Hysteresis of the Movement Axis of the Machine

The paper deals with the possibilities of measuring the residual displacement or hysteresis on the lateral direction of the movement forces caused by the cutting forces of the machining. A special adjustment of laser interferometry assemblies was used for measurement. The measurement results indicate that the positioning accuracy in addition to the cutting forces also influences the position of the displaced moving substances and the temperature. The complex effect of these parameters is greatly dependent on the design of the machine.

Elimination of Thermal Drift in Measuring the Positioning Accuracy of a Three Axis Milling Machine

The aim of this paper is to draw attention to more reliable verification method of positioning accuracy. The improvement lies in mathematical elimination of thermal impact during the measurement process. This thermal impact, always present during the motion of movable parts, is of a special systemic character. It increases the indefiniteness of measurement of the classic measurement method. This measurement uncertainty can be reduced by implementing the procedure introduced in this paper. The reduction can be achieved by separating the temperature impact from other sources of inaccuracy. Such separation is a very new solution. The methodology relies on mathematical processing and does not depend on the manner of accuracy measurement. The evaluation method also yields diagnostic information on the machine’s condition. The experiments were performed with the use of laser interferometer.

Information Contents of a Signal at Repeated Positioning Measurements of the Coordinate Measuring Machine (CMM) by Laser Interferometer

Abstract The input of this paper lies in displaying possibilities how to determine the condition of a coordinate measuring machine (CMM) based on a large number of repeated measurements. The number of repeated measurements exceeds common requirements for determining positioning accuracy. The total offset in the accuracy of spatial positioning consists of partial inaccuracies of individual axes. 6 basic errors may be defined at each axis. In a triaxial set, that translates into 18 errors, to which an offset from the perpendicularity between the axial pairs must be added. Therefore, the combined number of errors in a single position is 21. These errors are systemic and stem from the machine’s geometry. In addition, there are accidental errors to account for as well. Accidental errors can be attributed to vibrations, mass inertness, passive resistance, and in part to fluctuations in temperature. A peculiar set of systemic errors are time-varying errors. The nature of those errors may be reversible, for instance if they result from influence of temperature or elastic deformation. They can be also irreversible, for example as a result of wear and tear or line clogging, due to loosened connection or permanent deformation of a part post collision. A demonstration of thermal equalizing of the machine’s parts may also be observed in case of failure to adhere to a sufficient time interval from the moment the air-conditioning is turned on. Repeated measurements done on a selected axis with linear interferometer can provide complex information on the CMM condition and also on the machine’s interaction with the given technical environment.

Manufacturing Systems Building and Developing

The paper presents a complex of information aimed at automated production systems structures and simulation. For production systems intergrated structures formation it uses logistic principles for making the internal material flow among various logistic nodes more precise and effective, including respective information flow, here e. g. with use of integrable and compatibile handling and technological systems, as well.

2D-Shape Analysis Using Shape Invariants

High efficiency detection of two-dimensional objects is achieved by an appropriate choice of object invariants. The aim is to show an example of the construction of an algorithm for rapid identification also for highly complex objects. The program structure works in a similar way as animal systems in nature. Differentiating runs from whole to details. They are used to shape invariants. The program algorithm is specifically used a surfaces invariant, which represents a whole. Then was used a boundary length invariant around the object. Finally, the chord distribution code was used, which represent a detail of object recognition. The actual computational algorithms are not software-intensive and easy to debug. System uses the redundancy of uncertain information about the shape. In principle, chosen a certain balance between the confidence level of recognition and repetition of shape recognition by various methods.

Virtual Reality in the Maintenance of Machinery and Equipment

The paper deals with the possibilities of virtual reality applications in maintenance and servicing of machinery and technical equipment. It presents the results of experimental testing of new methods and techniques in the laboratory, in the process of implementation of maintenance operations in a virtual environment. It characterizes the hardware and software tools used in laboratory experiments.