Realizowany od lat 80. XX w. program „odbudowy miasta” zakłada uspołecznienie programów reform i polityki miejskiej. Celem artykułu jest ukazanie, jak program Krajowej Polityki Miejskiej przechwytuje i asymiluje ideały „bycia razem” (wspólnego bycia) wypracowane przez ruchy miejskie. Rządowe programy widzą w społeczeństwie „innowację” i nieuwzględniany wcześniej potencjał w planach rozwojowych. Dokonują „operacjonalizacji” ideałów i postulatów ruchów miejskich w taki sposób, by uczynić społeczeństwo nowym zasobem rozwoju ekonomicznego. Asymilacja i translacja roszczeń oraz ideałów ruchów miejskich przez programy rządowe zarządzania miastem staje się elementem nowej politycznej racjonalności.
Artykuł jest próbą analizy dyskursu przestrzenno-pedagogicznego na gruncie niemieckiej pedagogiki społecznej. Stanowi wycinek rozważań na temat zmiany w paradygmacie myślenia o miejscu/przestrzeni (spatial turn), jako kategoriach pedagogicznych. Autorki szukają odpowiedzi na pytanie, czym jest przestrzeń i miejsce oraz jakimi pojęciami w zakresie refleksji nad miejscem/przestrzenią operuje niemiecka pedagogika społeczna. Tekst przybliża między innymi relacyjną koncepcję przestrzeni Martiny Löw, jej dwuznaczność oraz pojęcie spacingu. Aktywne wytwarzanie przestrzeni miejskiej oraz przestrzenny wymiar relacji i jego dynamika poddane są dyskusji. Artykuł prezentuje również głosy krytyczne, dotyczące między innymi transdyscyplinarności przestrzeni oraz pracy socjalnej zorientowanej na przestrzeń socjalną. Stanowi zachętę do pogłębionych, międzynarodowych analiz teorii przestrzenno-pedagogicznych.
This work depicts the effects of deep cryogenically treated high-speed steel on machining. In recent research, cryogenic treatment has been acknowledged for improving the life or performance of tool materials. Hence, tool materials such as the molybdenum-based high-speed tool steel are frequently used in the industry at present. Therefore, it is necessary to observe the tool performance in machining; the present research used medium carbon steel (AISI 1045) under dry turning based on the L9 orthogonal array. The effect of untreated and deep cryogenically treated tools on the turning of medium carbon steel is analyzed using the multi-input-multi-output fuzzy inference system with the Taguchi approach. The cutting speed, feed rate and depth of cut were the selected process parameters with an effect on surface roughness and the cutting tool edge temperature was also observed. The results reveal that surface roughness decreases and cutting tool edge temperature increases on increasing the cutting speed. This is followed by the feed rate and depth of cut. The deep cryogenically treated tool caused a reduction in surface roughness of about 11% while the cutting tool edge temperature reduction was about 23.76% higher than for an untreated tool. It was thus proved that the deep cryogenically treated tool achieved better performance on selected levels of the turning parameters.
Titanium alloy (Ti-6Al-4V) has been extensively used in aircraft turbine-engine components, aircraft structural components, aerospace fasteners, high performance automotive parts, marine applications, medical devices and sports equipment. However, wide-spread use of this alloy has limits because of difficulty to machine it. One of the major difficulties found during machining is development of poor quality of surface in the form of higher surface roughness. The present investigation has been concentrated on studying the effects of cutting parameters of cutting speed, feed rate and depth of cut on surface roughness of the product during turning of titanium alloy. Box-Behnken experimental design was used to collect data for surface roughness. ANOVA was used to determine the significance of the cutting parameters. The model equation is also formulated to predict surface roughness. Optimal values of cutting parameters were determined through response surface methodology. A 100% desirability level in the turning process for economy was indicated by the optimized model. Also, the predicted values that were obtained through regression equation were found to be in close agreement to the experimental values.
The dynamics of the turning process of a thin-walled cylinder in manufacturing is modeled using flexible multibody system theory. The obtained model is time varying due to workpiece rotation and tool feed and retarded, due to repeated cutting of the same surface. Instabilities can occur due to these consecutive cuts that must be avoided in practical application because of the detrimental effects on workpiece, tool and possibly the machine. Neglecting the small feed, the stability of the resulting periodic system with time-delay can be analyzed using the semi-discretization method. The use of an adaptronic tool holder comprising actuators and sensors to improve the dynamic stability is then investigated. Different control concepts, two collocated and two model-based, are implemented in simulation and tuned to increase the domain of stable cutting. Cutting of a moderately thin workpiece exhibits instabilities mainly due to tool vibration. In this case, the stability boundary can be significantly improved. When the instability is due to workpiece vibration, the collocated concepts fail completely. Model based concepts can still obtain some improvements, but are sensitive to modeling errors in the coupling of workpiece and tool.
In the present work, the performance of multilayer coated carbide tool was investigated considering the effect of cutting parameters during turning of 34CrMo4 Low alloy steel. It has high strength and creep strength, and good impact tenacity at low temperature. It can work at –110°C to 500°C. And EN 10083-1 34CrMo4 owns high static strength, impact tenacity, fatigue resistance, and hardenability; without overheating tendencies. The objective functions were selected in relation to the parameters of the cutting process: surface roughness criteria. The correlations between the cutting parameters and performance measures, like surface roughness, were established by multiple linear regression models. Highly significant parameters were determined by performing an Analysis of variance (ANOVA). During the experiments flank wear, cutting force and surface roughness value were measured throughout the tool life. The results have been compared with dry and wet-cooled turning. Analysis of variance factors of design and their interactions were studied for their significance. Finally, a model using multiple regression analysis between cutting speed, fee rate and depth of cut with the tool life was established.
The objective of the investigation was to identify surface roughness after turning with wedges of coated sintered carbide. The investigation included predicting the average surface roughness in the dry machining of Duplex Stainless Steel (DSS) and the determination of load curves together with roughness profiles for various cutting conditions. The load curves and roughness profiles for various cutting wedges and variable cutting parameters were compared. It has been shown that dry cutting leads to a decrease in friction for lubricated surfaces, providing a small initial contact area where the surface is contacted. The study has been performed within a production facility during the production of electric motor parts and deep-well pumps.
Flank wear of multilayer coated carbide (TiN/TiCN/Al2O3/TiN) insert in dry hard turning is studied. Machining under wet condition is also performed and flank wear is measured. A novel micro-channel is devised in the insert to deliver the cutting fluid directly at the tool-chip interface. Lower levels of cutting parameters yield the minimum flank wear which is significantly affected by cutting speed and feed rate. In comparison to dry and wet machining, insert with micro-channel reduces the flank wear by 48.87% and 3.04% respectively. The tool with micro-channel provides saving of about 87.5% in the consumption of volume of cutting fluid and energy.
In recent times, the concept of hard turning has gained awareness in metal cutting as it can apparently replace the traditional process cycle of turning, heat treating, and finish grinding for assembly of hard, wear-resistant steel parts. The major apprehension in hard turning is the tool vibration, which affects the surface finish of the work piece, has to be controlled and monitored. In order to control tool vibration in metal cutting, a magnetorheological fluid damper which has received great attention in suppressing tool vibration was developed and used. Also an attempt has been made in this study to monitor tool vibration using the skewness and kurtosis parameters of acoustic emission (AE) signal for the tool holder with and without magnetorheological damper. Cutting experiments were conducted to arrive at a set of operating parameters that can offer better damping characteristics to minimize tool vibration during turning of AISI4340 steel of 46 HRC using hard metal insert with sculptured rake face. From the results, it was observed that the presence of magnetorheological damper during hard turning reduces tool vibration and there exist a strong relationship between tool vibration and acoustic emission (AERMS) signals to monitor tool condition. This work provides momentous understanding on the usage of magnetorheological damper and AE sensor to control and monitor the tool condition during turning of hardened AISI4340 steel.
The economic activity indicators in Poland during the years 1995‒2011 exhibit various cyclical patterns. Employing the Christiano – Fitzgerald band-pass filter and unobserved components model it is shown that the cyclical processes of Polish economic activity are driven by overlapping higher frequency fluctuations (3‒4 years) and longer cycles of 8.5 years. The cyclical fluctuations of construction, transportation and trade are dissimilar to gross value added. Economic activity in transportation leads and in construction lags the fluctuations of gross value added. Cyclical fluctuations of gross value added seem to be determined by industry and construction. Manufacturing, especially capital and intermediate goods fluctuations are responsible for the variation of industry. The production of non-durable consumer goods, energy and production of electric power are relatively the most desynchronized compared to industry. Production of electric power leads industrial production. Capital goods, intermediate goods and energy cycle phases are asymmetric – the slowdown lasts shorter and has higher amplitude compared to expansion. During the last crisis occurred the intensified variation of economic activity in Poland.