Robert Kohar

Robert Kohar
University of Žilina · Department of Design and Mechanical Elements

About

40
Publications
19,741
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171
Citations

Publications

Publications (40)
Article
Full-text available
This paper is focused on the theoretical study of heat conduction in the multi-brake system of the automated guided vehicle (AGV). The study aims to compare the amount of heat generated during braking from 10 m/s until a stop in a brake system based on organic and ceramic friction material. The theoretical study of heat conduction is solved in Matl...
Article
Full-text available
The article deals with the design of virtual reality (VR) interactive training as a teaching method and its effect on knowledge transfer and retention of students. The first part presents the methodology of the VR interactive training design. The second part utilizes the created interactive training for a case study to evaluate its effect on the te...
Article
Full-text available
The safety of machinery is a very important aspect for its correct functioning in the conditions of modern production or assembly. According to the standards, manufacturers of special-purpose machines and devices are obliged to provide their equipment with a certificate of conformity (CE). This article describes the concerns of insufficient safety...
Article
This manuscript is focused on the investigation of tribological and thermodynamic parameters of the coated C45 steel substrate. A metallic coating of the WC-Cu base was applied on the C45 steel substrate using electro-spark deposition (ESD) coating technology. Three types of experimental WC-Cu coatings with different ratio of chemical elements were...
Article
Full-text available
The article deals with an optimization procedure of roller elements geometry with regard to durability of spherical roller bearings. The aim of the article is to examine the impact of change of the roller elements inner geometry on durability and reliability of spherical roller bearings; the contact strain along a spherical roller by means of the F...
Book
This conference proceeding presents contributions to the 59th International Conference of Machine Design (ICMD 2018), organized by the University of Žilina, Faculty of Mechanical Engineering, Department of Design and Mechanical Elements. Discussing innovative solutions applied in engineering, the latest research and developments, and guidance on im...
Conference Paper
The aim of this paper is to detail the creation of a roller bearing model in the Adams program suite for subsequent dynamic analysis and to obtain information about different parts of the bearing during the simulation. The bearing model was made so as to closely resemble its real-life counterpart, which allows us to estimate load conditions, dynami...
Conference Paper
Nowadays, there is a great demand for technical solutions, which is the main reason why individual components have to be designed for limited weight, size minimization, accuracy and cost reduction. Weight reduction, utilizing less expensive materials, increasing the strength, etc. have always been desired in designing different mechanical structure...
Article
Full-text available
An analysis of a conventional gear wheel shot with MPK methodology has been processed by many authors before. Harmonic gearbox systems are composed of rigid and flexible parts through which the torque is transmitted, thus generating power. The contact pressure is specifically distributed through more teeth whilst against conventional gearbox system...
Article
Full-text available
AGV system already known today is commonplace in any large-scale production, warehousing or supply process logistics. System is not only increasing process flexibility but also the quality of products and services. They are unattended vehicles designed for towing, guiding and carrying various types of cargo using peripheral devices designed for the...
Article
Full-text available
This article deals with modularity of special-purpose machines in the automotive industry. The Slovak economy, by its interconnection to engineering and most to the automotive industry, often solves the lowest costs, whether in the sphere of production or in the field of assembly. This question is associated with the question of special-purpose mac...
Article
Full-text available
The article is focused on optimizing the friction disc plates of the braking system integrated into the drive wheel of an automated guided vehicle. The introduction is focused on the application of these types of braking systems. In the next step, the individual mathematical parameters and the acting forces in the braking system are expressed. Usin...
Article
Full-text available
The article is focused on braking simulation of automated guided vehicle (AGV). The brake system is used with a disc brake and with hydraulic control. In the first step, the formula necessary for braking force at the start of braking is derived. The stopping distance is 1.5 meters. Subsequently, a mathematical model of braking is created into which...
Conference Paper
Full-text available
Otázka konceptu Industrie 4.0 prináša mnoho zmien štandardnej sériovej výroby, ktorá sa mení na takzvanú bunkovú výrobu. Bunková výroba je istou formou sériovej výroby, ktorá rozdeľuje prácu do samostatných tímov známych ako bunky. Každá z týchto buniek musí dosahovať ciele ako kvalita, efektívnosť či znižovanie odpadu. Bunková výroba je riadená pr...
Conference Paper
Full-text available
The article has the task of getting to know about the design of the plastic bottle crusher. The device should work under the conditions of collecting yards and add economical value to the plastic waste by doing plastic flocks. The article describes a scheme of a crusher, and important construction nodes are described here together with calculations...
Article
Full-text available
This article deals with the problem of 3D meshing of ball-side parts of bearings. The article consists of 5 thematic units. In the first paragraph, the geometry of a bearing is being analysed with the basics of the simulation and its problems in general. The second part presents a generated 3D model of the bearing with the rolling solid. This rolli...
Article
Full-text available
The article deals with the influence of deformations of the individual components of the gearbox as well as their influence on the correctness of the gearing, which is essential for the correct functioning of the gearbox and its overall service life. In the next section the article deals with the effect of the gearbox deformation on the contact of...
Article
Full-text available
The current situation on a field of 3D print does not allow significant changes in the printer's construction. 3D printer's build area is often a limiting factor. The goal of this project is the design of a modular construction of a 3D printer. In the future, that would mean, that after purchase and after query for increasing build area, it would b...
Article
Full-text available
The current situation on a 3D print field is increasing precision of printers and printing of small parts. We have decided to use reverse philosophy and build 3D printer of big dimensions. This resulted in need of performing a dynamical simulation. The goal of this paper is to perform a dynamical analysis of moving parts of 3D printer and also to f...
Article
Full-text available
The article deals with the dynamic analysis of the mechanical system of the drive to the conveyor belt. Subject of the investigation is the behavior of the mechanical system at different operating conditions of the activity to the conveyor belt. Analysis of mechanical systems were set data necessary for the compilation of the various simulations of...
Article
Full-text available
The need to optimize the design of the structural node or the entire technical system returns the structural design or the whole production documentation back to the engineer's drawing board. Incentives to changes may occur in another lifecycle phase of the technical system. If a need to optimize arises, the engineer has more methods to choose from...
Article
Full-text available
In the field of engineering relatively new designs and manufacturing processes are constantly emerging. These changes are often seen in designing and manufacturing of prototypes or in single part production. We decided to analyse an aircraft propeller prototype using modern technologies. Existing aircraft blade design was converted to digital model...
Article
Full-text available
The aim of this paper is to detail the creation of a roller bearing model with flexible body cages in the Adams program suite for subsequent dynamic analysis and to obtain information about kinematic and dynamic relationships of steel and plastic cages under various operating conditions. The bearing model was made to closely resemble its real-life...
Article
Full-text available
The objective of this paper is to describe the procedure of correct determination of the optimum preload of tapered roller bearings in terms of their fatigue life, using the procedure laid down in ISO 281, and by analysis of contact stress state (analytically and by the FEM) with application of the Lundberg-Palmgren theory. The procedures will be a...
Chapter
The aim of this paper was to show the way to build a model roller bearings in the program execution Adams for dynamic analysis and obtain information about different parts of the bearing during the simulation. Bearing model was designed to be as close as possible to the actual deposit, which allows us to get an idea of traffic load, the dynamic con...
Chapter
This article highlights the possibility of including the effect of fits on the accurate calculation of the fatigue life of rolling bearings and limits of ISO 281, which provides the calculation of service life for over 60 years.
Chapter
This article discusses the effect of fits stiffness on distribution of internal loading in rolling bearings. Investigating effect of stiffness was performed by using the finite element method, because with the analytic method, this effect is impossible to include in the load distribution calculations on body parts, which transmit load in rolling be...
Article
Full-text available
The aim of this paper is to detail the creation of a large tapered roller bearing model with flexible body cages in the Adams program suite for subsequent dynamic analysis and to obtain information about kinematic and dynamic relationships of steel and plastic cages under various operating conditions. The bearing model was made to closely resemble...
Conference Paper
The aim of this paper is to detail the creation of a large tapered roller bearing model with flexible body cages in the Adams program suite for subsequent dynamic analysis and to obtain information about kinematic and dynamic relationships of steel and plastic cages under various operating conditions. The bearing model was made to closely resemble...
Article
Full-text available
This paper deals with accurate geometric models of rolling bearing components in the CAD system. This model is then employed to create a static structural analysis used to determine the size of stress between the components of a rolling bearing. Following the stress analysis, we specify the maximum load of a rolling bearing with regards to durabili...
Article
Full-text available
The aim of this paper is to detail the creation of a roller bearing model in the Adams program suite for subsequent dynamic analysis and to obtain information about different parts of the bearing during the simulation. The bearing model was made so as to closely resemble its reallife counterpart, which allows us to estimate load conditions, dynamic...
Article
Full-text available
This article details the design of an apparatus used in service life testing of large-scale rolling bearings on Faculty of Mechanical Engineering at University of Žilina. It describes individual steps in the design process, used parts and methods employed throughout the design process. One chapter is devoted to measurement techniques used in servic...
Article
This article discusses steps towards the design, construction and production of a device used for lifetime assessment of large-scale bearings. The machine is reviewed as a mechatronic entity, comprised of three parts - mechanical, electro technical and hydraulic. The mechanical part was designed with the help of modern CAD/CAE/PDM design systems al...
Article
Full-text available
Paper industry deals with procedures for conceptual and final design of a machine Intended for unwinding paper that remains on reels during a certain phase of paper producing. Design procedure of the machine is a subject of this paper. The machine was designed as a mechatronic unit consisting of a mechanical part, an electric part and a pneumatic p...

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Projects

Projects (2)
Project
The issue of the Industrie 4.0 concept brings many changes to standard series production that is transformed into so-called cellular production (cellular manufacturing). Cellular production is a form of serial production that divides work into separate teams known as cells. Each of these cells must achieve goals such as quality, efficiency, or waste reduction. Cellular production is driven by product and it is therefore essential that it be adapted to the product.