Advanced Materials Research Vol. 1036

Abstract: The tubular sections or shells for forming channels, drums, tanks or pressure vessel are manufactured by bending plates generally through three-roller bending machine and then welding the ends of bent plate to form a cylinder or cone. Force exerted on rollers during bending is one of the important criteria which must not exceed the capacity of bending machine. Secondly, Total bender capacity must be utilised during bending of desired curvature, which reduces number of passes and hence time required to attain desired curvature. Thus, it necessary to estimate the forces during bending, based on the roller position, so that it does not exceeds the bender capacity and simultaneously reduces number of passes. In this regards, some analytical models are available to predict the forces during three roller bending process with assumption of constant bend radius during bending. In fact, the radius continuously changes during bending operation which affects the magnitude and the direction of the forces exerted on the roller. An attempt is made to simulate the roller bending using FEA. Variation of curvature of plate and effect of various parameters such as plate thickness, bottom roller inclination and top roller inclination on bending forces during cylindrical and conical bending operation are studied using FEA analysis.

Abstract: The current work deals with numerical simulation connected to forming of a rectangular shaped part made from tailored blanks, having the welding line positioned symmetrical with respect to the part geometry. The objective was to study the relation between the blank holder force applied during forming and the thinning of the parents materials. All the parameters are fixed except the blank holder force, its variation will cause variation of the material thinning. The presented work is trying to demonstrate the important role of the blank holder force on the material thinning during the deep drawing process. It must be mentioned that both materials from the welded structure are having the same thickness (1mm). The Dynaform 5.8.1 software is used to simulate the forming process. The part obtained after each simulation is analyzed and measured to quantify the on the material thinning. All the parameters are maintained fixed except the blank holder force. The obtained results for five different binder forces (5, 10, 30, 50, 70 kN) were compared to realise the behaviour of the tailor welded blanks during deep drawing process. In the final part of this paper conclusions regarding the influence of the blank holder force on the material thinning are presented.

Abstract: Over the past years the target for waste recovery/ recycling has significantly increased in Romania, in according with the EU Directives. Nowadays, the competitive contexts of the current market lead the manufacturers to obtain novel and custom-made products using new technologies and quality raw materials. Such resources can be consisting of low-cost waste/by-products and in the processes of converting them into value-added products. On the other hand, the necessity for recycling waste is important under the strict European legislation. Regarding glass, the key sources of waste are container/ packaging glass, flat glass, electric and electronic equipments, domestic glass, E-glass, etc. According with source, waste glass can be: pre-and post-consumer waste glass. Now many recycling processes have been studied, developed and applied in industry. The major challenge is represented by creating of innovative and sustainable technologies and making it suitable. But recycling of glass is technologically more complicated than other waste (for example: paper). In case of glass, the most sustainable route is to use it for re-melting processes and obtaining a new glass. Glass is 100% recyclable but not all waste/cullet can be used for the manufacturing of any type of glass, due different chemical composition and the prohibitive shipping costs from collection points to glass factory. In this study, authors paid attention to the recycling process of soda-lime glass (post-industrial flat glass) and proposed the thermal embossing technique of glass, using glass slumping process, in order to obtain decorative products with aesthetic impact and functional role. An input image is prepared by applying different enhancement techniques, adjusting contrast, transferring into grayscale image in 256 shades of gray. The result image is transferred in Computer Aided Manufacture (CAM) software to refine the surface geometries and to obtain with rapid tooling the mould for glass. The method used for tooling fabrication consists of machining a block of suitable material with a Computer Numerical Controlled (CNC) machine which is known as a subtractive method. The next stage consists in applying of the heat treatment, using an electrical furnace. The major advantages of the embossing method for converting waste glass in value-added products is represented in the fact of use reduced energy comparing with the classic route of re-melting, possibility of obtaining bespoke products, ready to use in architectural and decorative fields. In addition, environmental benefits that results from processing waste glass are the reducing the raw materials (virgin) and the CO₂ emissions.

Abstract: The work presented in this paper refers to numerical simulation related to deep drawing of three parts having different geometry, as follows: square shape, cylindrical shape and semispherical shape. The current paper is trying to prove out the important role of the punch speed on the welding line displacement during the forming process. The punch speed influence is testes for the fallowing values: 100, 300, 600, 800 and 1000 mm/s. The punch stroke is 25 mm, which is the safe drawing depth for all three selected shapes. The parts are made from tailor welded blanks, having the welding line positioned as axis of symmetry. It must be mentioned that both materials from the welded structure are having the same thickness (1mm). The Dynaform 5.8.1 software is used to simulate the forming process. The part obtained after each simulation is analyzed and measured to quantify the displacement of the welding line. The welding line behave differently for each tested punch speed and also for each part shape. All the parameters are maintained fixed except the punch speed. The obtained results for those three shapes were compared to realise the behaviour of the tailor welded blanks during deep drawing process. In the final part of this paper conclusions regarding the influence of the punch speed and of the part shape on the welding line movements are presented.

Abstract: Conformities to law of changeability of the tool geometrical parameters, parameters of сut section, parameter of the chip formation, cutting forces, cutting temperature and machining surface roughness at machining of the shaped surfaces are set. There is researched character of change of the working edge angle, cutting face edge angle, width and thickness of cut section, cutting speed on position of blade top on the convex and concave shaped surface. The analytical dependences of the chip contraction coefficient, cutting forces, cutting temperature and machining surface roughness on the cutting speed and feed are certain. The method of determination of the cutting forces, thermal streams and cutting temperature at turning of the shaped surfaces is created taking into account changeability of the geometrical parameters and parameters of сut section. There are set coefficients, which allow expecting these parameters in any point of the convex and concave shaped surfaces. The method of account of the cutting process parameters changeability at optimization of the cutting regimes at turning of the shaped surfaces on the criterion of maximum productivity is developed. With the use of method of the linear programming analytical dependences of the optimum-cutting regime from the turning parameters taking into account variable limitations on cutting forces, cutting temperature and machining surface roughness are definite.

Abstract: This work is aimed at improvement of durability of especially thin disc tools, by means of controlling their dynamic parameters. It was found out that it is necessary to design tools and methods of reducing oscillations of the tool’s structure that could allow designing tools with thin and especially thin cutting pieces, ensuring the specified parameters of its durability, cutting precision and improvement of cutting modes. The performed investigations allow reducing substantially the cut’s width and ensuring the prescribed parameters of the tool’s durability, thus improving the overall technical and economic parameters of blanks cutting.

Abstract: Tools which generate by enveloping using the rolling method may be profiled using various methods. The substitutive circles family method is a complementary method developed based a specifically theorem, in which is determined a family of circles associated with the blank’s centrode, family which envelop the profile to be generate. The method assumes the determination of the circles family, transposed in the rolling process between the blank and tool centrodes. In this paper is proposed an algorithm for curling surfaces in enveloping, associated with a pair of rolling circular centrodes. The graphical algorithm is based on the representation of the circles family enveloped the blank’s profile. It is generated the circles family transposed on the centrode associated with the gear shaped cutter and is determined a new position of contact points with the blank. The assembly of these points forms the profile of the gear shaped cutter. The numerical data proof the proposed method quality.

Abstract: The spiroid gears are known and used due to their performances: increased gear ratio; reduced overall dimensions; the simplicity of the construction; increased carrying capacity on the gear flanks etc. The gears construction demand assurance of a certain geometry of the worm, which constitutes, in the same time, the basics for the generating tool of the spiroid wheel. In this paper, a worm with a composite profile is proposed. The profile is composed by an assembly of circles arc, in order to increase the length of the flank active zone. This design is intended to increase the contact length between the flanks of the spiroid worm and spiroid wheel, in order to decrease the contact pressure between the two parts and to improve the gear function process.

Abstract: This paper proposes an answer to a question like "it is better to use something new or use what we already know is a relatively recent technique novelty, which is found in tools manufacturer’s catalogues but still very rarely used, almost unknown in current industrial practice: spiral drill with three cutting edges. To give an endorsed answer, it starts machining a concrete case of a part of aluminium and research, based on a minimal experimental program, the processing with new drilling tool compared with the known helical drill. Answer the question initially is not simple, nor one given in few words and none with the high degree of generality, but one nuanced, depending on the performance indicators considered to be of interest and closeness of experimental working conditions than those found in current industrial environment. Helpful for the formulation and presenting the response is the processing of experimental data in the form of calculations, graphs and summary of the rejection’s causes. In this way, the concluding elements stand out more obvious and a number of partial answers can be formulated and justified recommendations can be done regarding: which of drills, where and in which conditions provides the best quality of machined hole, the best chip fragmentation and with the best ratio: price / quality / operation.

Abstract: The complex helical surfaces specific for the rotors of the helical compressors and of the screw pumps imply the production of a series of tools providing a high productivity. The staggered-tooth milling cutter achieve these conditions but their design gives rise to difficult problems. In order to optimize their parameters and to facilitate their design, a package of programs has been created to select the constructive parameters of the tool, to calculate the profiles of the plates, the angles of the surface of section, the dimensions of the elements of attachment. In order to include all these elements in an efficient system of design, a series of regular calculations were applied for various parameters that were then included through the CAD software for design and documentation AutoCAD; at the same time, several applications of verification, construction and simulation of the functioning of the tool and of the cutting process were designed. The method applied in this case reduced to a considerable extent the time of design and it also improved the constructive solutions of the staggered-tooth milling cutter.