Ľuboslav Straka

Operational Reliability of Mechatronic Equipment Based on Pneumatic Artificial Muscle

The aim of the contribution is to describe reliability control in technical equipment with focus on maximizing overall system reliability by the means of optimal selection of basic elements or by proper redundancy of the elements. The contribution describes the possibilities of increasing the reliability of pneumatic artificial muscle by the means of passive reliability increase of its parts. Further, possibilities of reliability increase by the means of active and passive reserve are described, as a higher level of reliability control in technical systems. In conclusion, summary of particular ways of reliability increase is presented on a concrete example of artificial muscle.

Study of Tool Electrode Wear in EDM Process

Technology of Electrical Discharge Machining (EDM) uses thermal energy in material removal, in which is the electrical energy transformed, generated between the electrodes (tool and workpiece). The material removal occurs through the rapid periodic repetitive electrical discharges in the presence of dielectric fluid. By the action of electrical discharges occurs to decline not only particles of a metal workpiece material, but also to decline in a certain proportion of metal particles in tool electrode. The paper deals with the diagnosis the size of the electrode wear of tools made from copper and graphite used in EDM machining.

Diagnostics of Production Systems Operation Based on Thermal Processes Evaluation

The paper describes a method of prediction values consistently transient events that can be described by a mathematical function. This article focuses on the thermal process. This allows a reasonable time to take appropriate control plot in the desired values of the variables borders. The article contains the results of the simulation and plot comparison of simulation results with the measured value.

Evaluation of Capability of Measuring Device on the Basis of Diagnostics

In capability evaluation of measuring devices on the basis of diagnostics, it is important to compare variability of measurement with certain proportion of tolerance zone width of observed qualitative parameter. Determined index of capability of particular measuring device indicates its applicability for inspection of selected qualitative parameters in a given tolerance range. The paper is focused on evaluation of capability of digital micrometer DIGIMATIC within its entire measuring range (0 to 25mm) by the means of capability index Cgm and Cgmk. Evaluation of capability of the given measuring device was carried out by repeated measurements of standards with dimensions representing lower, middle and upper range of the measuring instrument at given accuracy (2μm) of measuring device.

Research of the Basic Physical Regularities of Material Removal in Electrical Discharge Machining of Tool Steel

The paper describes the basic physical regularities of material removal in Electrical discharge machining (EDM) of tool steel. One of the parameters, that material removal regularities quite accurately identifies, is the tool wear rate (TWR). This parameter, however, describes only the regularities concerning the tool electrode wear. More complex parameter for assessing regularities of material removal in EDM is thus electrode wear ratio (EWR). This parameter, except the size of the wear of the tool electrode, also describes the size of the workpiece material removal. Research on material removal was carried out on samples made out of tool steel EN X32CrMoV12-28 using Cu-ETP electrode EN CW004A. Aim of this paper was also based on the selection of main process parameters that significantly influence the material removal in EDM to define the individual specifics with regard to minimizing EWR.

Impact Assessment of Input Factors on Tool Electrode Wear in Die Sinking EDM of Steel EN43CrMo4

The paper deals with the wear of tool electrodes for Die Sinking EDM. In the experiment were used the electrodes of copper and graphite. The workpiece material was steel EN43CrMo4. For the assessment the effects of each parameter was used the statistical method Design of Experiments (DOE). Assessed input factors were the peak current, pulse on-time, pulse off-time, and the electrode material. The result of the effects of each input factors was tool electrode wear. For calculating the relative wear of electrodes was used the percentage of the ratio of the electrode and the workpiece weight. The results show that the expression of the relative wear in practice can be described as a method unusable due to the absorption of the graphite electrode used in the experiment.

Influence of Process Parameters on Geometric Precision of Machined Surface after WEDM

Geometrical precision machined surface is generally understood as mainly precision shape, orientation, location and run-out. As a rule, it is measuring the appropriate deviations from the nominal surface. The geometric size of this deviation from the nominal surface can in practice affect the conventionally measured value for the dimension and the dimension whilst maintaining the required tolerance. Because the WEDM technology is among the most accurate technology, the small final geometric accuracy deviation has also a negative impact on the final quality of the machined surface. The paper aimed to describe errors geometrical precision of machined surface which occurs in wire electrical discharge machining (WEDM) and quantify their scope.

Quality Assessment of Machined Surfaces by an Optical Profilometer

Technological parameters affecting the surface quality of cutting edges in production system with the AWJ technology include cutting head movement speed. The article examines and evaluates the quality of processed surface by the AWJ technology on selected materials as related to the change of cutting head movement speed. It was discovered that the movement speed for the AWJ technology has a significant effect on the surface quality

Proposal of Preventive Maintenance Plan of Experimental Equipment

One of the basic means of improving the reliability of technical equipment is increasing their reliability through targeted maintenance. When designing any technical equipment should be chosen minimum necessary set of technical resources that are necessary to the achievement of the required scope and quality of its functions. By setting an appropriate preventive maintenance plan can be timely and effective interventions to prevent adverse consequences of failure. This paper describes the proposal of optimal plan of preventive maintenance of experimental equipment designed for 3D machining rotating parts with AWJ technology.

Determination of the Suitability of the Method Used for Evaluation Measurement Equipment Capability

Complex quality evaluation of manufacturing and control process is based on assessment of capability of measuring equipment. Substantiation of measuring equipment capability is evoked by constantly growing need to prove suitability of chosen inspection method from a view of global approach to inspection process. The contribution described evaluation of capability of digital indicator within its entire measuring range (0 to 12.7 mm) by the means of measurement equipment index Cgm and Measurement equipment index Golden Device Cgmk. Evaluation of capability of the given measuring equipment digital indicator Mitutoyo was carried out by repeated measurements of standards with dimensions representing lower, middle and upper range of the measuring instrument at given accuracy of measuring equipment 2μm.