Properties of low-alloy high-speed steel at elevated temperature

This paper presents the results of research on the determination of the coefficient of thermal conductivity and hot hardness of cutters made of selected grades of low-alloy high-speed steels, HS 6-5-2 and HS3-1-2. The investigations of hot hardness and yield stress values of HS6-5-2 steel at elevated temperatures have shown that the hot hardness value decreased to 650 – 700 HV (59 – 60 HRC) in the temperature range of 500 – 550 °C. However, the hardness of the samples preheated to the temperature of 500 – 550 °C and measured at room temperature does not change. A decrease of the hot hardness of the steel is correlated with decreasing yield stress at elevated temperature

Artificial neural networks and experimental analysis of the resistance spot welding parameters effect on the welded joint quality of AISI 304

The automobile industry relies primarily on spot welding operations, particularly resistance spot welding (RSW). The performance and durability of the resistance spot-welded joints are significantly impacted by the welding quality outputs, such as the shear force, nugget diameter, failure mode, and the hardness of the welded joints. In light of this, the present study sought to determine how the aforementioned welding quality outputs of 0.5 and 1 mm thick austenitic stainless steel AISI 304 were affected by RSW parameters, such as welding current, welding time, pressure, holding time, squeezing time, and pulse welding. In order to guarantee precise evaluation and experimental analysis, it is essential that they are supported by a numerical model using an intelligent model. The primary objective of this research is to develop and enhance an intelligent model employing artificial neural network (ANN) models. This model aims to provide deeper knowledge of how the RSW parameters affect the quality of optimum joint behavior. The proposed neural network (NN) models were executed using different ANN structures with various training and transfer functions based on the feedforward backpropagation approach to find the optimal model. The performance of the ANN models was evaluated in accordance with validation metrics, like the mean squared error (MSE) and correlation coefficient (R2). Assessing the experimental findings revealed the maximum shear force and nugget diameter emerged to be 8.6 kN and 5.4 mm for the case of 1–1 mm, 3.298 kN and 4.1 mm for the case of 0.5–0.5 mm, and 4.031 kN and 4.9 mm for the case of 0.5–1 mm. Based on the results of the Pareto charts generated by the Minitab program, the most important parameter for the 1–1 mm case was the welding current; for the 0.5–0.5 mm case, it was pulse welding; and for the 0.5–1 mm case, it was holding time. When looking at the hardness results, it is clear that the nugget zone is much higher than the heat-affected zone (HZ) and base metal (BM) in all three cases. The ANN models showed that the one-output shear force model gave the best prediction, relating to the highest R and the lowest MSE compared to the one-output nugget diameter model and two-output structure. However, the Levenberg–Marquardt backpropagation (Trainlm) training function with the log sigmoid transfer function recorded the best prediction results of both ANN structures

Investigation of frictional conditions of steel sheets using pin-on-disk tribometer

This paper presents a method of determining the anisotropic friction model for sheet metal forming processes based on experimental data obtained from the pin-on-disk tribometer test. Friction coefficient value was measured as a function of angular position with respect to the rolling direction of the sheet metal. The frictional investigations presented in this work were conducted for deep drawing quality cold-rolled steel sheet with a sheet thickness of 1 mm

Parametric Effects of Single Point Incremental Forming on Hardness of AA1100 Aluminium Alloy Sheets

When using a unique tool with different controlled path strategies in the absence of a punch and die, the local plastic deformation of a sheet is called Single Point Incremental Forming (SPIF). The lack of available knowledge regarding SPIF parameters and their effects on components has made the industry reluctant to embrace this technology. To make SPIF a significant industrial application and to convince the industry to use this technology, it is important to study mechanical properties and effective parameters prior to and after the forming process. Moreover, in order to produce a SPIF component with sufficient quality without defects, optimal process parameters should be selected. In this context, this paper offers insight into the effects of the forming tool diameter, coolant type, tool speed, and feed rates on the hardness of AA1100 aluminium alloy sheet material. Based on the research parameters, different regression equations were generated to calculate hardness. As opposed to the experimental approach, regression equations enable researchers to estimate hardness values relatively quickly and in a practicable way. The Relative Importance (RI) of SPIF parameters for expected hardness, determined with the partitioning weight method of an Artificial Neural Network (ANN), is also presented in the study. The analysis of the test results showed that hardness noticeably increased when tool speed increased. An increase in feed rate also led to an increase in hardness. In addition, the effects of various greases and coolant oil were studied using the same feed rates; when coolant oil was used, hardness increased, and when grease was applied, hardness decreased

Development trends in machines and techniques used in sheet metal cutting

W artykule przedstawiono zachodzące zmiany w maszynach sterowanych numerycznie wykorzystywanych w technologii kształtowania blach. Omówiono trendy rozwojowe w budowie maszyn do cięcia blach z uwzględnieniem laserowych i plazmowych wycinarek sterowanych numerycznie, wykrawarek matrycowych i wycinarek elektroerozyjnych. Przedstawiono także tendencje w zakresie zwiększania produktywności przez wprowadzanie nowych technologii oraz modernizację obecnie stosowanych.This paper presents changes in the numerically controlled tool machines in sheet metal forming technology. The article has also showed the characteristics of cutting machines including numerically controlled laser and plasma cutting machine, die cutting machines and machines for wire electrical discharge machining. Furthermore, the tendencies in increasing the productivity by development of new technologies and modernization recently used have been also presented

Analiza wpływu tarcia na zmianę topografii powierzchni wytłaczanych blach

In the article, topographical and tribological analysis of the surface of steel sheets is presented. Strip drawing tests were used to describe the friction phenomenon in sheet metal forming processes. The topographical analysis of tested samples was carried out by using the Alicona InfiniteFocus measurement system. The results of strip drawing tests were used as input variables in a mathematical model of friction. The friction tests were carried out in order to determine the influence of the surface parameter values of the sheets, the surface parameters of the rollers, and the pressure force on the friction coefficient value.W pracy przedstawiono analizę topograficzną powierzchni po próbie przeciągania blachy. Analizę wykonano za pomocą systemów pomiarowych Subtronic 3+ Rank Taylor Hobson oraz InfiniteFocus firmy Alicona. Badania mające na celu wyznaczenie wartości współczynnika tarcia dla zmiennych warunków tarcia wykonano na specjalnym przyrządzie umożliwiającym pomiar tensometryczny. Badania zrealizowano dla różnych warunków tarcia wynikających z zastosowania trzech kompletów przeciwpróbek walcowych o różnej chropowatości powierzchni oraz różnych wartościach sił docisku rolek w warunkach tarcia suchego i smarowania olejem LAN-46. Określono wpływ zmiennych warunków tarcia na zmianę wartości parametrów chropowatości przeciąganych blach. Generalną zależnością wynikającą z badań jest spadek wartości współczynnika tarcia wraz ze wzrostem siły docisku dla warunków tarcia suchego oraz przy smarowaniu olejem. Po przekroczeniu pewnej wartości obciążenia zależność między siłą tarcia a siłą docisku jest nieliniowa, a współczynnik tarcia nie ma stałej wartości i zmienia się wraz ze wzrostem nacisku. Ze zmianą warunków tarcia wiążą się zmiany topografii warstwy wierzchniej próbek. Przeprowadzone pomiary parametrów struktury geometrycznej powierzchni blach po wykonaniu prób przeciągania nie dały jednoznacznej odpowiedzi na pytanie o wpływ warunków tarcia na zmianę chropowatości powierzchni blach. Procesowi tarcia analizowanej blachy głębokotłocznej towarzyszy zmniejszenie parametrów amplitudowych Sa oraz Sq. Jest to spowodowane wygładzaniem powierzchni blachy na skutek plastycznego zgniatania wierzchołków mikronierówności. Jednocześnie wraz ze zmniejszeniem chropowatości powierzchni blachy zwiększa się udział powierzchni nośnej

Materiały i technologie w motoryzacji w aspekcie bezpieczeństwa i ekologii

The use of a particular material in the automotive industry is determined by its properties in the aspect of safety and the effects on the natural environment starting from production to its liquidation. We are constantly striving to reduce the costs of materials used while increasing the strength properties and the production of non-natural materials, e.g. composites. Among the modern materials appearing in the production of cars, a growing share of high-strength steels, plastics as well as light alloys based on aluminum and magnesium is observed. This article presents selected materials and technologies used in the automotive industry from the point of view of their impact on safety and environmental protection.O zastosowaniu konkretnego materiału w motoryzacji decydują jego właściwości w aspekcie bezpieczeństwa i skutków dla środowiska naturalnego począwszy od produkcji do jego likwidacji. Ciągle dąży się m.in. do obniżenia kosztów stosowanych materiałów przy jednoczesnym zwiększeniu właściwości wytrzymałościowych oraz wytwarzaniu materiałów niewystępujących w przyrodzie, np. kompozytów. Wśród nowoczesnych materiałów pojawiających się w produkcji samochodów obserwuje się rosnący udział wysokowytrzymałych stali, tworzyw sztucznych, a także stopów lekkich na bazie aluminium i magnezu. W artykule przedstawiono wybrane materiały oraz technologie stosowane w przemyśle motoryzacyjnym z punktu widzenia ich wpływu na bezpieczeństwo i ochronę środowiska

Methods of determination of frictional resistances in sheet metal forming of car body sheets

Zjawisko tarcia towarzyszące niemal wszystkim procesom przeróbki plastycznej, w szczególności procesom kształtowania blach jest złożoną funkcją właściwości materiału, parametrów procesu kształtowania, topografii powierzchni kształtowanej blachy i narzędzi oraz warunków smarowania. Podczas procesu kształtowania wytłoczek występują strefy zróżnicowane pod względem stanu naprężeń, stanu odkształceń, prędkości przemieszczeń i warunków tarcia. W artykule scharakteryzowano metody wyznaczania wartości współczynnika tarcia w wybranych obszarach kształtowanej blachy oraz przedstawiono wady i ograniczenia tychże metod.The friction phenomenon existed in almost all plastic working processes, in particular sheet metal forming, is a complex function of the material's properties, parameters of the forming process, surface topography of the sheet and tools, and lubrication conditions. During the stamping of the draw-pieces there are zones differentiated in terms of stress and strain state, displacement speed and friction conditions. This article describes the methods for determining the value of the coefficient of friction in selected areas of sheet metal and presents the drawbacks and limitations of these methods

Application of biomass-powered stirling engines in cogenerative systems

Due to the properties of different kinds of renewable energy as sources of energy for small farms in Podkarpackie province, cogenerative biomass technologies have proved the most suitable for its supplying. Special solutions based on direct combustion boiler coupled with biomass-powered Stirling engine are the most interesting. The characteristics and examples of use of cogenerative system based on Stirling engine are presented

Drying of herbal plants as a method of management of wasteland

The cultivation of herbs in Poland is one of the newest sectors of plant production despite the centuries-old tradition of using herbs across the world. Contemporary herbal processing in Poland is primarily oriented to the production of herbal medicines, as in many other European countries. The cultivation, harvesting and processing of herbs in small and medium-sized farms require machinery and devices adjusted to the scale of production. The processing of herbal plants involves drying, which is one of the most important stages of herb preservation and the most energy-consuming process occurring in agricultural production. A comprehensive review is presented covering the various methods used in agriculture to preserve herbal plants and the classification of solar-energy and hot-air drying systems. In addition the paper presents examples of the development of solutions using low-temperature herb dryers appropriate to small and medium-sized farms