Table of Contents


    • Roll leveler for straightening sheet blanks

      pg(s) 114-115

      The report presents the design of a 13-roll leveler for straightening sheet blanks of complex configuration. The roll leveler is equipped with a mechanism for controlling the roll gap, which during the levelling process compensates for the elastic deformation of the housing and maintains the specified levelling conditions. The levelling process was analyzed using the finite element method (FEM) with the determination of forces acting on the rollers during levelling of sheet blanks up to 50 mm thick.

    • Development and implementation of closed loop position control concepts on electromechanical linear system using Beckhoff controller

      pg(s) 116-119

      Electromechanical linear axes are used as actuators in many areas of industrial automation. Such axes are a fundamental building block of any machine tool, manipulator or similar device, whether they implement only one- or multi-axis positioning. Usually, servomotors or stepper motors are used to drive the axes, and the control is performed by a variety of PLC controllers and controller con cepts. The paper presents the implementation of a multi-purpose electromechanical linear axis, which enables the study, research and comparison of various linear drive concepts and types of closed loop controllers. The linear axis incorporates two different motor types: a BLDC servomotor as well as a stepper electric motor, and thus also enables comparison of these two motor types and corresponding control concepts. A multi-core Beckhoff soft PLC is used as a controller, which can implement either built-in closed loop controllers or can also implement controllers designed in the Matlab/Simulink environment.
      PID closed loop position controller built-in Beckhoff TwinCAT 3 is presented in the paper. Further on, it is compared by PID closed loop controller developed in Matlab/Simulink which was exported and imported into Beckhoff TwinCAT 3 environment in order to confirm the adequacy of importing and using Matlab/Simulink controllers on Beckhoff soft PLCs.

    • Research of the stress state of a gantry crane track

      pg(s) 120-122

      The technology of work in some industrial enterprises involves the using of the heavy lifting machines moving on a special railway track. The type and dimensions of the gantry crane and the crane track are in accordance to the size and weight of the processed loads and the final product. The gantry cranes and the crane tracks usually work outdoors in all weather conditions and aggressive environmental influences. Most of these facilities were built 30 ÷ 40 years ago. During this period the regulations and requirements for their operation have been changed. Digital technologies now allow more precise modeling and calculation of the structure of the crane track, as well as inspection the impact of individual elements on the stress state of the structure as a whole.
      The effect of the present study will have the greatest impact on loading and unloading platforms in railway stations, harbors and intermodal terminals.


    • Possibilities of reducing the degradation of molds for high-pressure of Al alloys

      pg(s) 123-126

      The paper focuses on the degradation of molds that are used for the technology of high-pressure casting of Al and its alloys. The method of high-pressure casting of aluminum products is one of the widely used production methods, which at the same time meets the requirements for precision and productivity in the production of cars and various mechanical parts. In the high-pressure casting process, the molds are exposed to various thermal and mechanical loads, where the molds and their shaped parts are degraded. The paper presents the results of research focused on the use of duplex PVD coatings to increase the life of shaped parts of molds for high-pressure casting of Al and its alloys.

    • Study of the defect closure behaviour during forging in a step-wedge strikers

      pg(s) 127-129

      This work is devoted to the study of the internal defect closure during metal broaching in step-wedge strikers with wedge and depression by FEM in Deform program. A through cylindrical hole with a diameter of 3 mm was considered as an internal defect. At the same time, three variants of the defect vertical location were modeled – in the workpiece center, near the upper face of the wedge and near the lower face of the depression. In all three cases, the internal defect closure is uneven. The most intense defect closure is observed when it is located in the workpiece axial zone. Defects located near the strikers surface zones are not closed well enough. The stress-strain state analysis showed that the defect location affects the distribution nature of stresses and strains along the workpiece section.

    • Method for repair and recovery of defected industrial reinforced concrete structures through an effective thin repair overlay

      pg(s) 130-133

      The bearing monolithic reinforced construction of “Open Fuel Storage” of SOLVAY SODY AD, Devnya, has been operated for more than 40 years in conditions of extreme stress and external aggressive factors. All this has logically led to the presence of serious corrosion damages. The basic requirements for developing a technical solution for repair and restoration of defect structures retaining walls (assembly type), supporting beams and columns, is the bringing of the technical characteristics of the reinforced concrete structure in its initial (design) or better condition. The report discusses the features of the proposals as the most effective technological method for repair, based on the possibilities for the formless construction of a new special thin repair concrete layer restoring the original cross-section, applied with the methods of “wet” shotcreting. A composition of high -tech concrete with the participation of an internal crystallization chemical admixture and a shrinkage-compensating one suitable for shotcrete is proposed. Specific details have been developed for the renovation of the individual structural elements, as well as optimal technological regulations for the implementat ion of the repair.

    • Testing of nitinol sensor on bending deformed polypropylene tube: comparison of winding methods

      pg(s) 134-137

      A thin nitinol wire with a diameter of 0.05 mm was used as a surface sensor indicating deformation changes of the polypropylene tube during bending. Two types of nitinol wire windings were compared: parallel placement with the longitudinal axis of the tube and transverse windings around this axis. Changes in the electrical resistance of the wire were measured during the bending deformation. The sensitivity of the nitinol sensor, its comparison with conventional wire metal resistance strain gauge made of constantan alloy, its application possibilities, as well as the advantages resulting from the different winding geometry were discussed.


    • Investigation of Heat-Treated Steels Using the Magnetic Noise Method

      pg(s) 138-141

      This paper presents the results of an investigation conducted on samples of high-quality heat-treated carbon steel using the magnetic noise method. The objective of the work was to find the proper informative parameters for identifying the obtained s tructures with different hardness. To this end, samples were prepared using quenching and tempering heat treatment at different temperatures , from 150°C to 500°C. After microstructural analysis and hardness measurements, the samples were investigated using the magnetic noise method. The signals were visualized and analyzed using a digital oscilloscope and the Multi Instrument 3.8 software program. The RMS informative parameters and the registration time of the magnetic noise signals were used to identify the obtained microstructures with different characteristics and hardness.

    • Mesoporous transition metal oxide composites for effective remediation of air from VOCs

      pg(s) 142-145

      This study is aimed at the preparation of mesoporous Cu-Ti-M oxide composites (M=Ce, Zr, Sn) by combination of template assisted hydrothermal technique with the conventional impregnation or novel “chemisorption -hydrolysis” techniques. The obtained materials are characterized by nitrogen physisorption, XRD, SEM, FTIR, HRTEM, XPS, TPR and tested as catalysts for ethyl acetate oxidation, as a probe VOCs molecule. The regulation of the microstructure, surface and redox properties and the related catalytic behavior of the composites by changing of the metal oxide dopant and preparation technique used is discussed in details.

    • Strain controlled fatigue of 40X steel

      pg(s) 146-149

      The fatigue strength of 40X steel at 25 oC was determined following ASTM E606M standard for strain-controlled tests. The studied experimental dependence was modelled with a power function as well as with the functions and coefficients described in the standard. The material expresses plastic properties for cyclic loadings above 0.2% strain amplitude.