The smart factories that are already beginning to appear employ a completely new approach to product creation. Smart products are uniquely identifiable and know both their current status and ...alternative routes to achieving their target state. Smart factories allow individual customer requirements to be met, meaning that even one-off items can be manufactured profitably. In smart industry, dynamic business and engineering processes enable last-minute changes to design and production, delivering the ability to respond flexibly to disruptions and failures on behalf of suppliers. This paper presents a case study of product development and design process renovation according to changeability paradigm in one-of-a-kind industrial environment. It demonstrates how integration of changeability with agile design strategies crucially contribute to improve the operations of a highly individualized product development business. Successful management of ‘never-ending’ engineering changes appears to be the most important aspect in this field. Contribution of the presented work is a generalized framework that demonstrates how companies in such specific environments can improve competitiveness through the utilization of changeability concepts. The included case study validated the proposed changeability model and offers valuable insights into how to implement this in practice.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The topic of this paper is the application of abrasive flow machining (AFM) to gear tool inserts polishing. Polished surface on plastic gear teeth improves surface geometry stability, and it ...increases the lifespan, which was proved on the gear testing rig. Experiments have shown that it is an efficient alternative to the hand polishing procedure. Besides significant cost and processing time savings, AFM generates constant surface quality. The achieved roughness is homogeneous on the entire machined surface; it is reduced from
R
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= 0.68 μm to
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= 0.08 μm in 120 s. At the same time, the tooth geometry profile is not damaged. The first time, surface polishing should be done at request because of individually manufactured tool inserts. Processing parameters depend on the type of the abrasive machine, the polishing paste and part geometry. Computer-aided abrasive flow analyses and practical experiments assist in setting optimum AFM process parameters. The paper presents a working set of parameters and a detailed report on machined surface measurement data. On the base of better understanding of AFM process, the surface roughness prediction model and thickness of removed material model was setup. It has high accuracy and reliability for specific applications. The use of plastic gears for various applications is widespread; the presented process improvement is an important innovation for injection molding tools manufacturers.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This work presents a developed mathematical model that transforms functions and functionalities as sets from the functional domain and design elements domain. The sets are interconnected by a matrix ...model which we called the matrix of function and functionality (MFF). By the MFF model we are searching cross-sections of function and functionality sets. The cross-sections we called submatrices. Submatrices contain design parameters that designers need for development of new product conceptual variants. MFF is conceived as a tool used in conceptual design phase. MFF collects and binds data from the requirement list and transforms them into functional requirements. Compared to the morphological matrix, MFF is structured as multidimensional matrix, which according to the mathematical model presented in this work, generates a functional structure as multilayer functional structure. MFF simulates the iterativity of the design process in conceptual phase, generating new conceptual variants. According to the mathematical model of MFF, a Computer application was made and also presented in this work.
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•Developed thermo-mechanical model produces results consistent with exp. measurements.•Model enables the consideration of any type of spur gear tooth profile.•High-speed thermography offers detailed ...insight into thermal response of polymer gears.•Tooth flash temperature gradient quickly dissipates after meshing cycle completion.•Geometric tolerance deviations influence the temperature rise on a given tooth pair.
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The presented work is focused on the development of a comprehensive thermo-mechanical model for predicting the temperature rise in thermoplastic polymer spur gears with any desired profile geometry while running. The specific constitutional behavior of thermoplastics influences the gear-meshing pattern, which can deviate substantially from ideal gear meshing, as typically exhibited by metal gears in moderate-loading conditions. Taking this aspect into account is of paramount importance if realistic temperature-rise predictions are to be made. The thermal response of the considered gear pair is studied thoroughly from both the analytical and experimental standpoints. Good agreement was found between the results of the model and the experimental measurements performed using a high-speed thermal imaging infrared camera, although it was also observed that the real-life temperature rise can increase noticeably if large geometric tolerance deviations from the ideal profile geometry are present. The presented experimental approach also offers the possibility to observe the temperature rise inside and outside the meshing cycle.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
This paper presents an investigation of different topological designs of steel-frame towers for the purpose of telecommunications usage, where the antennas are mounted at the top of the tower. The ...towers are subjected to different loads, such as self-weight, antenna loads, wind loads, ice loads and their combination (wind has an effect on iced towers because of the increased surface area). The results of the load impacts are compared to each other on the basis of comparative criteria, such as the criteria of ultimate limit states, the criteria of angular rotation at the antenna mounting, the structural mass criteria and economic evaluation of the structures. The comparison revealed some of the structural features of each topological design.
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This paper examines parameters that could influence geometric part deviation (shrinkage and warpage) of the Housing (Cycoloy, PC/ABS, Grade C2800) produced by plastic injection molding. Five ...parameters (temperature of molded plastic, injection time, cooling time, holding pressure, holding pressure time). Influence of the parameters is compared by simulation and real experiment with the results measured at five points. Taguchi's orthogonal array method is used. The simulation leads to unreliable results, with too many parameters influencing geometric deviation. Factor that has major influence is holding pressure time (HPT). The real experiment identifies holding pressure (HP) as a parameter with major influence. For further examination, the real experimentation is recommended, whenever it is possible.
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•Experimental tensile and bending tests performed on polyoxymethylene samples.•Anand viscoplastic model used for polymer gear meshing mechanical analysis.•Contact response found to be ...influenced by the viscoplastic material component.•Low influence of viscoplastic properties on generated frictional heat found.•For steel-polymer pairs the heat partition coefficient is a time dependent function.
The nonlinear material properties of thermoplastics like polyoxymethylene (POM) can influence the thermo-mechanical response of polymer gears to applied running loads. In the presented study, the non-elastic strain rate- and temperature-dependent mechanical characteristics of POM are examined, along with their influence on the mechanical response of the polymer gear at the tooth root and contact interface, and the resulting heat generation driving the commonly exhibited temperature rise during gear meshing/running. A detailed experimental study of these properties was conducted, employing standardized and partly customized tensile and bending tests. Using a suitable viscoplastic constitutive material model, calibrated based on the obtained experimental results, a numerical structural-contact analysis of the gear meshing process was performed, which could subsequently be used for a more detailed evaluation of the generated frictional heat and resulting temperature rise during gear running. While a significant influence of the viscoplastic material properties on the mechanical contact response and the flash temperature rise on the POM gear was identified, no major impact on the long term nominal temperature rise was recognized.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
In this paper we present a software package for computational modeling of single particle motion in static and dynamic external magnetic and electric fields and show applications of our package to ...general cases and particular cases of space, laboratory and fusion plasmas. In addition we further elaborate on the properties of a new concept named Larmor Center Trajectory that we introduced in our previous work D. Erzen, J.P. Verboncoeur, J. Duhovnik, N. Jeli, Int. J. Multiphys.
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, 419 (2007) as a generalization of the well known guiding center approximation, and show the ranges of applicability of this concept, especially in strongly inhomogeneous fields when adiabatic approximations break.
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Currently, the production of a high-quality and highly aesthetic prosthesis is still mainly based on handwork and subjective comparison to get the proper shape and colour of the prosthesis, likely ...not by a first attempt. This article describes a case study whose goal was to investigate the possibilities of computer-aided surface reconstruction and supplementation to improve the quality and reduce the manufacturing time for an orthopaedic prosthesis. For this purpose, a model of human finger made of plaster had been scanned with the high fidelity laser triangulation scanner. The result was a set of very dense point clouds, representing the surface of the finger model in all its complexity. The main target of this work was to create a water-tight, high resolution computer model of a human finger, which would be ready for further manipulation, such as scaling, mirroring or stretching in arbitrary dimensions. A larger amount of such models could represent a virtual database of human shapes, which would be suitable for prosthesis production and many other (medical) purposes. The first steps after scanning were done in an attempt to reorient several scans, taken from different viewpoints, relative to each other in order to get the proper shape of a finger. This was done by applying an ICP algorithm, integrated in commercial software, and its comparison to the results of reorientation, based on information about finger's position transformation during the scanning process. This information proved to be vital for a fast and accurate alignment of the scans and successful surface generation. This paper also discusses the possibilities of avoiding the influences of geometric errors, generated by a triangulation scanner on surface alignment and the creation of a 3D model. The surface was created by applying Delaunay triangulation to the point cloud. Afterwards, it was followed by manual and automatic refining and reconstruction of a triangular mesh. The final result is a 3D computer model of a human finger with all its details, such as fingerprints and wrinkles. Additional measurements showed that the arithmetical average of deviation between a computer and a physical model was less than 0.3 mm, which is a good result for the desired purposes. The study also showed the possibilities for acceleration of scan alignment while the accuracy could be increased.
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BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The ability to manage engineering changes (ECs) efficiently reflects the agility of an enterprise. A large majority of products become gradually improved and perfected through the ...developmental-design process, during which the set design requirements are met or even upgraded, thus prolonging the product life cycle. The concept of product improvement was based on the activation and tracking of (ECs) through the developmental-design phase and the manufacturing phase. A special method was used to recognize activities within the process and the degree of involvement of individual participants. The individuals involved in the process were provided with appropriate information and the required communication channels with others were ensured. The EC process was generalized and applied to different types of production. A product's complexity and design level were analyzed first, and key factors such as CE methods, process definition, information system, communication and organization were used as a tool for optimizing the EC process. The method was tested and successfully applied into industrial practice.
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