Fulltext search in archive

To achieve much higher operation parameters of EAST device, some key components are upgraded. Fast control coil as one of the key components is updated by using novel stainless steel mineral insulation conductor and the turns are increased to 4, which means the coil's operation environment becomes more severe and larger loads will be encountered. The coil joint is apt to be destroyed in view of the potential defects during the fabrication. Given the numerous advantages, the induction brazing is being considered for the conductor joint connection. The copper mock up is used to carry out the feasibility analysis. Based on the structural size of copper tube, the brazing parameters are calculated and a 2 turns splitting induction coil is designed. Some influence factors effecting the induction efficiency are analysed. It will provide guidance for choice of power supply and the optimization design of induction coil. In addition, the induction experiment is launched and comprehensive joint performance tests are subsequently performed. The test results indicate the joint overall performance could satisfy the basic engineering design requirement, but also some defects are found and more study should be carried out and to further improve the brazing quality.

Automatic workpiece exchange is one of the important parts of every flexible manufacturing system. This part largely allows complete automation of the component's production cycle. It also greatly contributes to a significant reduction in the workpiece clamping times and contribute to a reduction in the downtime during the machining process. It also allows eliminating a human factor from the production process, thereby contributing to greater machine utilization and higher machining productivity. This article describes certain modifications of interchangeable pallet system designated for specific training CNC machine tool EMCO Concept Mill 105 situated in the laboratory at the Department of Automation and Production Systems. This machine has considerably limited workspace and length of feeds which are the most limiting parameters during design. Mentioned modifications allow manipulating with designed pallets with the industrial robot or special manipulator instead of previously designed manual handling.

Lightweight constructions are in demand for applications which require low weight accompanied by rigidity. From this perspective, lattice structures are an interesting design solution in conjunction with additive manufacturing technology. This study addresses promising lattice topologies. A range of metallic lattice structures was produced using Direct Metal Laser Sintering technology and the samples were exposed to uniaxial tensile load. During the tensile tests crack initiations and locations of the breaks were observed. The results clarify the weaknesses of the cellular lattices and reveal their maximum tensile load. First steps have been taken to meet the demand for optimized lightweight AM products.

Presented research paper is focused on the development of carbon fibre wheel. Considering development and construction of wheels for the automotive and motorcycle industry, low weight is one of the most significant factors. In the case of rotating components, the imbalance of the assembly is a problem. This fact affects handling of the vehicle or wheel behavior under the load, for example in the point of turning, acceleration or drive on damaged road. Determination of the most appropriate material composition (sequence) is primarily the main problem of composite material application. Correct design of material composition and also lay-up diagram is determined by material characteristics and strength requirements. A suitable solution is in the application of a group of input material structures creating hybrid composite. Specific combination of various input materials (aluminum ring, 3D printed plastic honeycomb core and carbon fibre composites) guarantees and ensures the fulfilment of the strength requirements which are determined during each particular application. The main aim of presented paper was to design material composition and shape of carbon fibre wheel that were subsequently verified by successful manufacturing process.

Main goal of this study is to describe and design manufacturing system which is using Additive manufacturing technology for production of semi-finished products and conventional machining technology for finishing operations, then demonstrate requirements of such production on simulation model on production planning and then analyze and summarize the outputs of the production model. The model is made with aid of modern Digital Factory tools. The main purpose of the model is to provide a complex tool for this study in order to analyze and optimize the fictive production system in needed range and complexity. The topic of Rapid Prototyping and Additive manufacturing technologies is very recent topic in industry. But still, there are only few examples of production systems, which are really using Rapid Prototyping technologies as a part of the production or production line. The advantage of these technologies is their versatility, but on the other hand, as a part of production system, they can have different demands on for example production planning, area consumption or maintenance, that can affect whole production system.

The traditional Mixed-model Assembly Lines (MMALS) balancing and sequencing serial design methods are difficult to adapt to rapidly changing requirements. From the perspective of the parallel design of balancing and sequencing, a mixed integer linear programming model for MMALS balancing and sequencing is proposed. An improved particle swarm optimization (PSO) algo-rithm was proposed, in the process of updating the optimal solution, the simulated annealing (SA) algorithm is added to make it possible to jump out of the local optimum with a certain probability and expand the solution selection to the entire population. Based on the algorithm, random coding and ascending decoding methods are proposed, the number of products and the number of tasks are coded and decoded at the same time. Verify the effectiveness of the algorithm by an example.

This paper presents some advanced techniques on CAD modelling and CAM programming for 5-axis machining of free-form surfaces. In the CAD stage, based on surface partitioning, the design surface can be created with separate regions such as convex, concave and saddle. Point-based techniques are used to create the original surface and the boundary curves of the regions. Some other CAD/CAM techniques for determining tool sizes and tool orientations are also proposed to generate gouge-free tool paths for each region. A simple B-spline surface was given as an example to demonstrate the proposed techniques implemented in Creo Parametric. The points on the design surface and on the boundaries were generated by a Matlab program developed by the author.

Tubes of super-heaters and heaters used in conventional power plants are exposed to coolant and high temperatures. The growing oxide layer on the inner surface reacts over time as a heat insulator on the water side and reduces heat transfer through the wall of the tube. A relatively thin oxide layer already contributes to the boiler efficiency and causes a permanent overheating of the tube wall. As a result of overheating at the site, the intercrystalline cracks leading to the bursting of the tube are developing. The secondary problem of the growth of oxide layer thickness is so-called exfoliation. For non-destructive evaluation of the thickness of the oxide layer directly at the power station, ultrasonic method (UT) can be used with a high frequency probe. In order to verify the accuracy of the measurement and the qualification of the ultrasonic testing methodology, light and Scanning Electron Microscopy (SEM) was used on specimens that were removed from the super-heater after the UT measurement. The standard longitudinal cut surface imaging in BackScatter Electrons (BSE) and Energy Dispersive Spectroscopy (EDS) analysis for accurate thickness determination with the chemical composition of the layer confirmed the accuracy of the UT measurement.

This paper presents the theoretical and practical aspects of industrial robots transport systems problems focused on application possibilities connected with concrete type of robotic device. Introduction of the article presents today possibility of robot transport systems and collect information about basic technical parameters of transport systems, their design and construction. Main part describe industrial robot ABB IRB 140, collect information about technical parameters, its construction, axes, motions and applications used in industrial practice. Practical part of paper is focused on proposal of robot transport system design from manufacturing point of view.

The article deals with the wear of the blades of the delimber device of harvester head. An input analysis of the materials of the fixed knife and movable arm parts was performed. It consisted of chemical analysis, evaluation of microstructure and hardness measurement by HRC and HB methods. The original welded joint was analyzed, which ensured the connection of the blade and the fixed, resp. movable arm mechanism. Based on the findings, two blade replacement solutions have been proposed. The first was the application of hard metal by an OK 84.58 electrode and second use HARDOX 450 by welding with a fixed part or a mechanical gripping with screws. This was recommended based on previous research at the Faculty of Technology. The hardnesses of the original blade material were compared with the proposed solutions. The correctness of the proposed methods will be verified in the future and in operation.

Hard-to-machine materials conclude a variety of materials. In this group of materials are high-strength, hardness-resistant steels, such as austenitic steels, but also non-ferrous alloys with high cor-rosion, heat resistance and strength based on nickel, titanium or cobalt, etc. For machining of these materials, it is necessary to choose suitable tools. The improper cutting tool can cause an increase in geometric inaccuracies, rapid wear, etc. Cutting material is an important factor during designing of cutting tools. A combination of a proper cutting tool with the trochoidal milling can reduce maching time, extend tool lifetime and reduce production costs.

In terms of physical and chemical properties, titanium and its alloys are among the most important construction materials today. The Ti6Al4V alloy can be classified among high-strength materials with good plasticity, corrosion resistance and other valuable properties. When performing operations associated with long-term heating of workpieces and parts made of titanium alloys in an air atmosphere, a TiO2 layer is formed on the surface of the product. Ti6Al4V alloy, also known as Ti64, in terms of microstructure is a two-phase alloy formed by α+β solid solutions, which has excellent corrosion resistance and biocompatibility. This alloy is also suitable for jet engines, gas turbines and many aircraft components, as well as in biomedicine. Heat treatment can further improve its technical properties, reduces stress, improves machinability, fracture toughness. The surface of alloys can also be thermally stressed when micro and nano layers of material are applied, which serve to extend the life of products made of this alloy. The presented article analyzes the effect of heat treatment at temperatures of 550 °C and 600 °C and corrosion load with salt fog in the range of 168 to 720 hours on the microstructure and microhardness of the Ti6Al4V alloy.

Production of primary aluminium is energetically enormously expensive. The use of secondary (recycled) aluminium, has therefore a high potential to save money and energy while reducing the negative environmental impact of aluminium production. Although the properties of secondary aluminium alloys are generally comparable to those of primary aluminium alloys, the increased Fe content can lead to a significant reduction in the corrosion resistance of these alloys. Secondary (recycled) AlSi7Mg0.3 cast alloy with different iron contents (0.123, 0.454, 0.679 and 1.209 wt. %) in the as-cast and after heat treatment (T6) condition was investigated. The quantitative analysis was focused on the evaluation of the Fe-phases, especially the needle-like Al5FeSi phase. The corrosion resistance was measured by a rapid corrosion test (AUDI test). The corrosion damage of the surface was observed macroscopically. The results show that Fe content higher than 0.454 % has no significant effect on the amount and size of needle-like phases of Al5FeSi. The corrosion resistance is mainly influenced by the size and length of the Al5FeSi phases. Increased Fe content decreases the corrosion resistance of AlSi7Mg0.3 alloy and accelerates the initiation of corrosion.

The AGVs or mobile robots are well used in today’s manufacturing supply technologies and also can be used in engineering’s education. The motion controlling and simulation of such vehicles are a cru-cial question. This paper introduces the steps of motion planning for a driverless carrier vehicle from the positions initially available to the speed of the wheels. The vehicle is located in the High-Tech Logistics Systems Laboratory of the Logistics Institute of the University of Miskolc. For motion con-trolling and simulation between two points the further modules are necessary: 1. path planner, 2. tra-jectory planner, 3. velocity-voltage converter using velocities gained from trajectory planner, 4. mo-tion controlling and simulation of a motor dynamical model using voltages from the converter, 5. simulation of the path and 6. data processing. In this paper the first two modules are detailed, i.e. the path planning and then the trajectory planning. Path planning is based on a new approach, using Bezier-curves and Hermite curves. The trajectory planning tends to the mininum energy, which can be carried out by the examining the current consumption created in the other modules. The smaller consumption originated from the two curves determines the final path and trajectory.

Technological progress in the 21st century has catalysed the industrial revolution (Industry 4.0) following the development of multiple new industrial automation technologies in the manufacturing sector. Regardless, past research indicated the unsuccessful attempts in adopting Industry 4.0 technologies among manufacturing organisations. Undoubtedly, the operationalisation of Industry 4.0 in manufacturing proved challenging as organisations were required to evaluate various aspects for effective implementation. Thus, a sound understanding of constructs concerning employees’ acceptance and readiness levels towards novel automation technologies was required. Hence, this study aims to explore, develop, and validate the suggested conceptual framework by integrating the Technology Acceptance Model (TAM) and Technology Readiness Index (TRI) with Exploratory Factor Analysis (EFA). The EFA process was the first crucial step in ensuring the internal consistency and stability of the instrument across the sampling population. Consequently, the research outcome potentially enabled the manufacturing sector to identify and comprehend the key determinants in designing industrial automation technologies. This study also contributed to knowledge on technology acceptance by synthesizing TAM 3 and TRI 2.0 theories, thus constructing a new TAM in manufacturing.

The paper considers questions asotiated with automated systems to produce composite parts. Exist-ing automated systems used in aerospace production are usually based on lay-up technologies. The main objective of the on-going development is to find an affordable production technology for com-posite parts that can be easily automated. The handling with dry reinforcing fabrics is objective of the paper: dry fabric is placed in a suitable mold where it is impregnated by selected type of a matrix and consolidated under vacuum bag afterwards. Based on experiments using standard gripping systems, it was found that local damage of reinforcing fibers occurs. For these reasons, a new vacuum suction-based gripper was developed. As a suction source industrial vacuum cleaner was used, whose perfor-mance can be regulated continuously. Functionality of the suction system was verified on six differ-ent types of reinforcing materials, using two different types of suction grid at three different levels of vacuum cleaner performance. Performed experiments verified suitability of the designed solution for manipulation with dry fabrics without the risk of their damage.

Mechanical alloying and subsequent compaction with spark plasma sintering was chosen for the fabrication of investigated CoCrFeNiTi alloy method. The alloy was characterized in terms of chemical and phase composition with X-ray fluorescence spectroscopy and X-ray diffraction spectrometry, respectively. The microstructure was examined using light microscopy and scanning electron microscopy equipped with an energy dispersion spectrometer. The alloy showed an ultra-fine grained uniform microstructure composed mainly of an FCC solid solution with a volume fraction of HCP Laves phases. Regarding mechanical properties, the prepared specimen reached an ultimate compressive strength of 1340 MPa with the hardness of 757 HV 30. The wear rate of the sample reached 1.19 · 10-4 mm3·N-1·m-1 showing traces of adhesive-abrasion wear mechanism.

Natural fibre-reinforced polymer (NFRP) composites can be environmentally friendly and cost-effective alter-natives to synthetic fibre-reinforced composites. Major industries have expressed significant interest in the advancement of new natural fibre-reinforced composite materials. However, these materials perform poorly on their own and require further analysis since accessible information is lacking in the literature. This paper presents the results of previously reported works on natural fibre reinforced polymer composites, with strong attention to the types of fibres employed, the polymers used in the matrix, the treatment of fibres as well as the test parameters. The best proportion of composites is consequently selected. Composite materials are tested using a CNC router machine. Pinewood dust is combined with vinyl ester resin. A hand layup tech-nique is used to prepare the samples. The availability of relevant pinewood dust and the volume of pine wood dust to be used are first determined to continue with the experiment. According to the findings, the impact of machining performance is successfully evaluated by employing the tensile strength test, Charpy impact test, flexural strength test and surface roughness measurement. The findings are derived from the microscopic assessment of the surface roughness of pinewood dust (PWD) fibre reinforced vinyl ester resin.

The effects of punch radius, deep-drawing speed and amplitude on the friction coefficient were studied on an improved drawing-bulging friction coefficient testing device on basis of ultrasonic vibration. A contact friction model based on the tribology theory of adhesion and plowing was constructed and used to explain the friction reduction phenomenon of applied out-of-plane normal vibration. The results show that the friction coefficient decreases with the increase of ultrasonic vibration amplitude. At the same deep-drawing height, the friction coefficient decreasing rates at amplitude of 7.8um and 10.1 um on the deep-drawing speed of 0.1 mm/s and 10 mm/s, were 6.7% and 18.8%, respectively. the friction coefficients at the punch radii R0.3 and R1.5 declined from 0.18 to 0.13 and from 0.12 to 0.11. The friction coefficients of thin specimens were larger than thick specimens whether ultrasonic vibration was applied or not. The average friction coefficient from theoretical modeling (μ_v) was smaller than the friction coefficient without ultrasonic vibration (μ_0), and the relative friction coefficient ratio declined with the rise of amplitude and was inversely proportional to time.

At present, electromagnetic induction quenching and nitriding are two commonly used surface strengthening approaches applied in improving the strength of the steel parts. In this paper, a comparative study was proposed to research the strengthening effect of these two technologies in improving the fatigue strength of steel crankshaft. First a modified statistical analysis approach of the fatigue limit load was proposed to obtain the distribution of the fatigue limit load. Then two types of steel crankshafts were selected to be the object of research and treated by these two techniques. Finally the standard T and F hypothesis testing methods were conducted in evaluation the strengthening effect. The results showed that compared with the nitriding approach, the electromagnetic induction approach can improve the fatigue strength of the steel crankshaft more obviously, thus is more suitable for engineering applications.

The milling process is widely used industrially and the quality of the obtained milled products should be controlled because it affects their performance in exercise. This work correlates the quality of the machined surfaces with the adopted locating system, the shape deviations of the workpiece datum and the machine tool. An analytical model was set up and implemented through Matlab® to simulate the quality effects of a milling process. It was applied to two face milling processes characterized by two different locator configurations. It was proved that machine tool volumetric error influences the flatness of the milled surface, while the locator configuration and the datum form deviation affect the orientation of the milled surface, as should be actually.

Atomic Diffusion Additive Manufacturing (ADAM) is a recent metal sintering process based on known composite printing technology. ADAM can be classified as indirect additive production using fibre of metal powder bound in a plastic matrix. The plastic binder allows the metal powder to remain in place when is printing. Thus, a "green part" is printed and then the plastic binder is removed by the post-washing and sintering process. The aim of this work is providing a brief description of the ADAM process patented by Markforged. Furthermore, the main task was to compare the technology with other sintering technology, namely SLM technology. It works on the basis of selective bonding of metal powder using the thermal energy of the laser beam. Parameters, such as dimensional and shape accuracy, roughness of printed surfaces or tensile strength of printed samples were examined and compared. Dimensional accuracy of the ADAM process was evaluated using ISO IT grades - determined on the basis of the reference standard. The observed accuracy of the sintering process was comparable to traditional production processes.

The present work describes the influence of Al content on the CoCrFeNiAl high-entropy alloys pre-pared by the powder metallurgy technique. The preparation procedure consisted of mechanical alloy-ing and subsequent spark plasma sintering. The content of Al varied from 10 – 30 at.% which affected the microstructure and mechanical properties. Using scanning electron microscope (SEM) and X-ray diffraction analysis (XRD) was found the microstructure becomes more refined with increasing con-tent of Al accompanied by the annihilation of the ductile FCC solid solution (Cr0.25Fe0.25Co0.25Ni0.25) phase and growth of the brittle and hard BCC solid solution phase (α-Fe) and formation of Al(Co0.5Ni0.5) phases, improving the mechanical properties. The best combination of the porosity, hardness HV 30, and ultimate compressive strength (UCS) was achieved for the studied high-entropy alloy when it contained 20 at. % Al.

This study is focused on testing the ballistic resistance of composite materials to define their limit thicknesses according to the US STANDARD NIJ 0101.06, level III. The materials Twaron CT 747, Twaron CT 747 TH110 and Endumax Shield XF33, which are widely used in the manufacture of the ballistic protection systems, were tested. A method known as the Taylor Anvil Test (TAT) was used to verify their ballistic resistance. The missile 7.62 mm M80 was used to test the ballistic resistance of these materials. Within the experimental part, the deformation processes of composite materials were examined after impact by this missile. The value of the traumatic effect according to the US STANDARD NIJ 0101.06 was also measured. The results of the experiment provide an idea of the ballistic resistance of selected materials. Based on the results, TAT proved to be the perspective measurement method for further development and optimalization of the multilayer composite armor.

This paper describes some tools usable for quality control in plastic injection moulding. The introductory part presents tools for quality management, the use of which is demonstrated in the next part using a practical example. The selection of suitable methods was based on proven methods for quality management. They were selected to work in synergy. The author's contribution is the modification of the PDCAI method, which was enriched by another step, namely, innovation. The last part of the article presents is a demonstration of FMEA, Ishikawa diagram, and Pareto diagram.

The goal of the study was to conduct a preliminary analysis of the kinematics of tram-pedestrian collision in case of a side impact. A T6A5-type tram, traveling at the speed of 10 km/h, was used for the crash analysis and reconstruction of the collision. The pedestrian response was analyzed using a crash-test dummy. For the purpose of this study, the postimpact dummy movement was approximated by the motion of its center of mass (COM) and only the translation movement in the frontal plane of the dummy (along the horizontal and vertical axes) was considered. The results showed a significant change in the coefficient of restitution after the initial impact. At first, the coefficient of restitution was high (e = 0.94), suggesting an almost perfectly elastic collision, followed by a sharp decrease (e = 0.07) within a short period of time (t = 0.02 s) that suggested an almost perfectly inelastic collision. After that, the coefficient of restitution reached a plateau phase with the values ranging from 0.18 to 0.32 and corresponding to a percentage loss of kinetic energy falling within 89 % and 97 %. The preliminary analysis of this study highlighted some features of side-impact tram-pedestrian collision and its kinematics.

The constantly developing aerospace industry places demands on increasing productivity and produc-tion efficiency. At present, new construction materials are being produced that have better physical and mechanical properties than conventional materials. In addition to new materials, new cutting materials and new machining technologies are being developed. The combination of suitable machin-ing technology, material and tool will achieve excellent product surface quality, long tool life and thus production efficiency. Due to its mechanical and physical properties, technical ceramics can be used in the machining of difficult-to-machine materials, in which there is mechanical stress on blows, impacts, abrasions and other damage. Thanks to these properties, ceramics as a material is very suit-able for the production of machine tools. The presented article deals with the applicability of ceramic milling cutters in high-speed machining of nickel alloy, which is used mainly in the aerospace indus-try. The evaluation of the experiment took place by means of DoE - analysis of cutting forces, the result of which is the creation of the dependence of cutting forces on cutting conditions. Based on the data obtained, it is possible to continue to further intensify the cutting conditions in the area of high-speed machining.

In the present study, an innovative method is proposed to improve the accuracy of thermal models of the grinding process. To this end, a set of orthogonal experiments are carried out to calculate heat flux using infrared temperature measurements. Then the convective heat transfer coefficient is modified based on the heat transfer and hydrodynamics theories. Finally, the modified heat flux and convective heat transfer coefficient are applied and a thermal model is established using ANSYS software. To verify the accuracy of the proposed model, a finite element grinding residual stress model based on the grinding heat and grinding force is established. By measuring the grinding residual stress and comparing it with the finite element residual stress model, the effectiveness of the grinding thermal model is indirectly verified. The obtained results demonstrate that the modified grinding thermal models are accurate and can be applied in engineering applications.

The paper deals the production of porous aluminum materials that are characterized by lower density and mechanical properties. Samples of porous aluminium materials were produced on the basis of the developed methodology that applied sodium chloride particles of different sizes (average size 4, 6 and 9 mm). The AlSi12 foundry alloy was preffered for the production of the aluminium porous material. As part of the experiments, samples of porous aluminium material in the shape of a truncated cone were made. The cavity of the foundry mould was in the shape of a truncated cone with diameters: D = 0.047 m, d = 0.040 m and height v = 0.040 m. The material properties were determined on the produced samples. Their weight, volume and their density, relative density were calculated. Based on empirical relations, their value of Young's modulus of elasticity and value of thermal conductivity were determined. The compressive strength of selected samples was monitored as well. The value of Young's modulus of elasticity was determined from the measured stress-strain course. Furthemore, the porosity of the produced samples was evaluated on a scanning microscope.

In this article, we studied the phenomenon of instability which is the buckling of the beam elaborated of steel (E36-S355), and magnetorheological elastomer subject to compression-flexion solicitation. The study of the influence of the intensity of the magnetic field on the buckling instability of compressed hybrid beams is done by a mathematical development using the Ritz approach and by a numerical simulation under the Abaqus calculation code. The obtained results show clearly that we can control the instabilities of the adaptive intelligent beams behavior by the magnetic field.