Search

Use of welding technology for the repair of steel castings is particularly common in two areas. These include weld surfacing of protrusions that remained incomplete after casting, or filling the surface defects (cavities). These defects are more common for steel casting than for graphite cast iron, due to the lower fluidity of steel. This article describes a suitable technological process of repairing the defects on the casting using the welding technology. A specimen produced for this purpose was prepared by carving a groove into a cast steel plate 20 GL, which was then filled with a weld metal using MAG (135) technology. The following evaluation of the basic characteristics of the repaired site point to the suitability of the selected technological parameters of the repair procedure. Metallographic evaluation was carried out, further evaluation of mechanical properties by tensile test, bend test and Vickers hardness test. The proposed methodology for the evaluation repair of foundry defects in steel castings also meets the requirements for the approval of welding procedures in accordance with the relevant valid legislation. Web of Science 18 2 180 177

Nowadays the automotive industry is predominantly using heterogeneous welded joints. The welding of an austenitic and galvanized steel sheet is one of the most common applications, which are using resistive spot welding (RSW); it is a process in which contacting metal surfaces are joined by the heat obtained from resistance to an electric current The electrodes used influence the quality of a heterogeneous welded joint. This paper describes the influence of the electrodes used, their material and shapes ; and the final heterogeneous welded joint, which consists of two or three sheets. They will be compared with each other two electrode materials: CuCr1Zr original (material used for both electrodes) of new material CuCr1Zr (upper electrode replacement) and CuCo2Be (removable bottom electrode). Furthermore, the improved electrode geometry where the original planar electrode is passed to the electrode with radius surface, due to poor access to the point of welding. The aim of this research was to achieve a better quality of spot welded joints consisting of two or three sheets. Web of Science 25 5 1277 1274

The aim of the article was to check the internal defects in the butt welded joints by non-destructive TOFD (Time of Flight Diffraction) technique. Subsequently, the macrostructure from the defect indication site was evaluated and assigned to the TOFD ultrasound indication. Basic knowledge of ultrasonic TOFD testing are described in the theoretical part of a submitted paper. Ultrasound technique TOFD is non-destructive method that can detect internal defects inside test material without damaging it. It is a reliable method for detecting mainly flat internal defects such as incomplete root penetration, lack of fusion, etc. Ultrasonic test procedures and test results obtained in non-destructive testing of butt weld are shown in experimental part. Evaluation of the ultrasonic TOFD testing results, its advantages and disadvantages are described at the end of this article.

The durability of classic structural steels against various types of wear is generally low. Therefore, various types and combinations of resilient materials are constantly evolving, which are designed to reduce the cost of components replacement or repairs. This paper deals with the structures that are formed in a weld after addition of tungsten carbide particles to protect the surface of the components from wear. The resistance of the weld surface layer containing tungsten carbides is also evaluated in comparison with a layer without these particles. Web of Science 59 4 472 470

Es wird ein Verfahren fur den Entwurf einer Technologie fur das Wasserstrahlschneiden von Materialien vorgestellt, das auf der Bestimmung der Konstanten der Schneidbarkeit von Materialien unter Verwendung eines abrasiven Wasserstrahls Kawj nach vier verschiedenen Ausfuhrungen basiert: Version A, bei der drei Deformationsparameter auf dem Testschnitt gemessen werden, namlich die ausgewahlte Tiefe hx [mm], die lokale Rauheit Rax [μm] in der Tiefe hx und die lokale Abweichung der Schnittspur von der Normalebene Yretx in der Tiefe hx; Version B, bei der lediglich zwei Verformungsparameter gemessen werden, namlich die Bezugstiefe het [mm] und die Abweichung der Schnittspur von der Normalebene Yretx [mm] oder Variante C, bei der nur ein Parameter gemessen wird, namlich entweder die Ultraschall-Wellengeschwindigkeit vLUZ [m · s–1] oder der Elastizitatsmodul Emat [MPa] (Kawj wird hierbei aus den entsprechenden Deformationsparametern berechnet). Die letzte Moglichkeit ist die Version D, wobei das Design der gesamten Technologie durch die Berechnung von Kawj mittels des Elastizitatsmoduls Emat oder mittels der Ultraschall-Wellengeschwindigkeit vLUZ des geschnittenen Materials durchgefuhrt wird.

Protective layers include special weld deposits, utilizing e.g. ferrous, nickel or cobalt matrices in combination with tungsten carbide particles, which according to their properties belong among so-called composite materials, and which have slowly replaced conventional components produced from tool steels. A weld deposit with an iron-based matrix (Megafil A864M) was used, with tungsten carbide particles on steel S235JR+N. The high- level hardness of tungsten carbides together with a tough matrix allows achieving high resistance to different types of wear. This resistance significantly increases the lifetime of machine components and thus it reduces the costs of companies needed for repairs or the replacements of machine parts.

SPR sensor with matrix arrangement of nanostructured golden spots enables both the study of low concentrations of substances in solution and the acquisition of information on the spatial layout of the diagnosed medium in solution. The linear response of this sensor was experimentally specified for standard solutions of alcohols in a concentration range of 0.01 - 0.5 wt%. The influence of signal noise generated by carrier substance flowing through sensing dots has been removed by data processing. This approach enables to determine refractive index changes less than 3 × 10-6.

This article deals with the study of defects in steel wire. In the study we model magnetic fields around rope genetated by magnetized part of rope. The work is based on the finite element program ANSYS. For the purposes of the experiments we consider one strand wire rope construction. We define different kinds of defects and faults. The shape of the magnetic induction lines of generated fields depends on the size of the defect, the depth of rope violation or the presence of other nearby defects. The location and number of disturbances have been chosen to achieve the most versatile outputs. All of these modifications were analyzed and the results displayed in the 3D colored.

Osnovna ideja rada je prikaz toka vrijednosti uz identifikaciju izvora troškova i nedostataka, koji će pomoći da se razotkriju skrivene pričuve u proizvodnji. Analiza obuhvaća postojeće stanje u pojedinačnim postupcima na proizvodnoj traci. Nakon prepoznavanja postojećih nedostataka napravljen je plan racionalizacije u kojemu je rabljena kombinacija elemenata lean proizvodnje. Predložena bi se rješenja mogla primijeniti kad se primijene principi lean proizvodnje na pojedinim dijelovima montažne trake u cijelom pogonu. U slučaju da se predloženo rješenje ne može primijeniti u praksi može se koristiti kao model za druge vrste poboljšanja kao što su smanjenje otpada i nedostataka., The core idea of the paper is a value stream mapping with identification of waste sources, and drawbacks which help to uncover hidden reserves of production. The analysis covers the current state of individual processes within the production line. After determination of the present drawbacks the plan of rationalization was created in which the combination of elements of lean production was used. The proposed solutions could be used when establishing the principles of lean production at particular sections of the assembly line within the whole plant. In case that proposed solution cannot be put into practice it can be used as a blueprint for other types of improvement respectively decreasing of waste and drawbacks.

Praca približuje problematiku automatizovaných metod merania rozmerov, pricom rozsiruje doteraz znamy obzor použivaných pristupov K meraniam O navrh novej, doteraz nepouživanej, metody. V praci popisovaný sposob merania rozmerov vychadza Z principu vlastnej lokalizacie inercialnych senzorov, schopných popisovať aktualne hodnoty uhlových rýchlosti a zrýchleni V smere jednotlivých suradnicových osi priestoru. Nutným predpokladom presnosti týchto merani je jasna definicia nulovej polohy systemu V priestore a zohľadnenie sirsieho spektra vplyvov okolia. Metoda by mohla umožniť meranie rozmerov tvarovo zložitých objektov S vysokou presnosťou, a to dokonca aj na miestach, kde by to pri použiti konvencných metod merani nemuselo byť vždy možne. Prispevok taktiež informacne popisuje principy funkcie inercialnych navigacných systemov a technologie MEMS, ktora znacne znižuje naklady na použitie týchto pokrokových technologii.

It is important that the computer technology used in interactive teaching is independent on the platform being presented on as well as the newest ICT standards are, used. The authors consider the design of a suitable technology to implement the computer model of a virtual technological work-place in so that they are used for teaching and testing manipulation control operations.

Actual trends of worldwide railway transport development are characterized by increasing speed and growth of railway’s axels load. Increasing load together with transverse, longitudinal wheel displacement and braking on the rails results into heavy surface tension. One of many applications for bainitic steel is in railway transport for highly strength and wear resistant rails. Rail steel must be designed to be able to resist plastic deformation, wear, rolling contact fatigue, bending stress and thermal stress during rail welding process and rails resurfacing.

The development and application of new materials brings, in connection with their technological machining, a number of new questions. Classical methods of machining are supplemented by new technologies. An abrasive water jet represents a universal flexible tool enabling the machining of all natural and artificial materials that are not damaged by direct contact with water. Great attention is paid to the study of the cut surface topography after abrasive water jet machining. The study of surface topography is important from the point of view of modelling and prediction of the topographic function of the abrasive water jet. On the basis of knowledge of the topographic function, we are able to optimise the technological parameters of the abrasive water jet machining process, which has an impact on the output, quality and price of the final product. The mechanism to remove material is an area which has not received much attention. In material disintegration, the mechanisms of cutting, plastic deformation, fatigue and fracture participate physically. By studying the surface topography we can better understand the process of abrasive water jet machining, specify the theory and correctly quantify the mechanism of material removal, which is the subject of this paper.

The paper deals with abrasive waterjet titanium tangential turning. Titanium grade 3 with a diameter of 55 mm was used as an experimental material. Technological conditions of turning tests were the same by gradually changing value of traverse speed (vf = 1,5; 3; 4,5; 6; 7,5 mm・min-1). Experiment tests were performed by using continuous abrasive waterjet of pressure p = 400MPa, by rotation n = 60 rpm of workpiece. The abrasive particles (Barton Garnet) were fed to the waterjet in the amount of 0,4 kg・min-1. It was determined that acceleration of traverse speed did not increase the surface profile parameters.