Ústav výrobních strojů, systémů a robotiky
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- ItemThree-axes error modeling based on second order dual numbers(Springer-Verlag, 2015-11-17) Holub, Michal; Hrdina, Jaroslav; Vašík, Petr; Vetiška, JanThe aim of the paper is to employ the dual numbers in the multi axes machine error modelling in order to apply the algebraic methods in computations. The calculus of higher order dual numbers allows us to calculate with the appropriate geometric parametrization effectively. We test the model on the phantom data based on the real machine tool. The results of our analysis are used for the geometric manufacturing accuracy description of the work space, together with the reduction of the measuring time.
- ItemExperimental Study of the Volumetric Error Effect on the Resulting Working Accuracy—Roundness(MDPI, 2020-09-08) Holub, Michal; Jankových, Róbert; Vetiška, Jan; Šrámek, Jan; Blecha, Petr; Smolík, Jan; Heinrich, PetrCurrently, various types of software compensations are applied to machine tools. Their aim is to increase the working accuracy of the tools. The improvement in working accuracy is then further assessed according to the increase in the dimensional and shape accuracy or the surface quality of the workpiece. This publication describes the effects of the volumetric accuracy of a machine tool on the working accuracy of a workpiece, where total roundness (RONt) is evaluated in multiple cuts. In the experiment, two test workpieces are manufactured on a three-axis milling machining centre. The first is made using a standard machine setup while the second with activated volumetric compensation. The LaserTRACER self-tracking laser interferometer is used to compensate for volumetric accuracy. In the second part, verification measurements are performed with a Ballbar, where roundness error is evaluated according to ISO 230-4. Then two test workpieces are machined, and, in the last part, measurement is performed on Talyrond 595S roundness measuring equipment. Finally, the results are analysed and the dependence between the volumetric accuracy, the circularity error of the machine and the working accuracy of the CNC machine tool is established, represented by the RONt of the workpiece. This paper presents new and unpublished relations between the volumetric accuracy of the machine tool and the RONt of the workpiece.
- ItemCNC Machine Tool Safety From The Aspect Of Hazard Perception By Operating Personnel(MM publishing, 2022-10-01) Blecha, Petr; Marek, Jiří; Blecha, Radim; Rozehnalová, Jana; Heinrich, Petr; Pacher, PetrSafety of machinery, including CNC machine tools, must be ensured in all phases of their life cycle. The operation and maintenance phase is the most important as it represents the longest period in the machine ' s technical life linked to occurrence of work injuries. Every designer of a safe machine must consider also any reasonably foreseeable incorrect behaviour of the machine operator. The latest revision proposal of the Machinery Directive 2006/42/ES sets new requirements on solution of CNC machine tools safety. Aside from assessing the impact of cybersecurity on the machinery safety, the manufacturers will now have to take into account also the psychological stress arising from human-machine interaction. From the psychological point of view, the operating personnel of multifunctional CNC machine tools experience high level of stress when machining complicated and complex-shaped workpieces as the material often costs as much as 30% of the price of the machine; therefore, any mistake of the operator resulting in a nonconforming product causes high financial loss. Influence of various stressors on the operating personnel leads to their impaired concentration on the performed tasks, which may be accompanied by insufficient perception of the hazards associated with the machine operation and thus may lead to occurrence of work injuries. The presented paper discusses the factors that may put the operators of multifunctional CNC machine tools under psychological stress and analyses possible application of the virtual reality technology to assess the ability to perceive the hazards linked to such a complex machine on a group of university students representing both operators (beginners) and designers of a multifunctional CNC machine tool.
- ItemCapability of measurement with a touch probe on CNC machine tools(Elsevier, 2022-04-12) Blecha, Petr; Holub, Michal; Marek, Tomáš; Jankových, Róbert; Mišún, Filip; Smolík, Jan; Machálka, MartinIncreasing the productivity of high-precision manufacturing requires efficient product inspection, for example, using integrated scanning systems on CNC machine tools (MT). However, measuring the dimensional and shape accuracy of workpieces using a touch probe (TP) on MT is negatively affected by the geometric accuracy setting of the MT, thermal stability of the MT and its surroundings, type of scanning system. The aim of this paper was to examine the possibilities of assessing the capability of touch probe measurements on MT, to define the size of the permissible controlled tolerance of the workpiece and to assess the influence of the geometric accuracy of the machine on the size of the permissible tolerance parameter of the inspected workpiece. In the presented experiments, the calculation of the TP measurement capability is based on a new approach respecting the VDA5 standard extended by the minimum tolerance (TOLmin) conformity assessment procedure according to ISO 14253-1:2017.
- ItemImplementation of Digital Twin for Engine Block Manufacturing Processes(MDPI, 2020-09-30) Bambura, Roman; Šolc, Marek; Dado, Miroslav; Kotek, LubošThe digital twin (DT) is undergoing an increase in interest from both an academic and industrial perspective. Although many authors proposed and described various frameworks for DT implementation in the manufacturing industry context, there is an absence of real-life implementation studies reported in the available literature. The main aim of this paper is to demonstrate feasibility of the DT implementation under real conditions of a production plant that is specializing in manufacturing of the aluminum components for the automotive industry. The implementation framework of the DT for engine block manufacturing processes consists of three layers: physical layer, virtual layer and information-processing layer. A simulation model was created using the Tecnomatix Plant Simulation (TPS) software. In order to obtain real-time status data of the production line, programmable logic control (PLC) sensors were used for raw data acquisition. To increase production line productivity, the algorithm for bottlenecks detection was developed and implemented into the DT. Despite the fact that the implementation process is still under development and only partial results are presented in this paper, the DT seems to be a prospective real-time optimization tool for the industrial partner.