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S. Buljan

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S. Buljan, Darko Šunjić, M. Sućeska, Safet Isić

Summary Explosive energy can be used in metal forming processes, e.g. for bulk forming, sheet forming and for other processes. This paper presents the experimental research and numerical modelling of the process of sphere deformation by explosive forming. The assembly for forming a sphere with a diameter of 210 mm was welded from flat segments and annealed after welding. The material of the sphere was steel St12 according to DIN 1629/3. The thickness of the sheet metal was 2.0 mm. The sphere was modelled in the SolidWorks program and 3D-printed with the polylactic acid (PLA) material. The Poladyn 31ECO explosive was used for the experimental investigation into the process of deep drawing of the sphere by explosion, while the LS-DYNA hydrodynamic software was used for simulation. The pressure in the sphere was measured with a pair of copper crushers. It is shown that the simulation satisfactorily reproduces the experimentally measured pressure.

Darko Šunjić, S. Buljan

Explosive forming is one of the non-conventional impulse technologies of metal forming technologies and it is a relatively young technology that has not been fully explored. The origin, development and application of explosive forming technology is given in this paper, and the advantages and disadvantages are also described. Given the specificity of this technology, this paper presents the calculation of the mass of the explosive as the most important factor in this process and the calculation of the pressure of the shock wave. In fact, with conventional deep drawing technologies, it is possible to design the technology and follow the same steps to reach products of different dimensions. In explosive forming, this is a problem, and it is not possible to follow these rules. Experiments of explosive forming can only be performed by employees trained to work with explosives, following prescribed procedures.

I. Karabegović, Mirha Bičo Ćar, M. Šestić, Savo Stupar, E. Husak, E. Karabegović, M. Mahmić, Safet Isić, Samir Vojić et al.

Currently, the world is facing major changes. Research and development of innovations in new technologies, the rapid pace of implementation of these innovations and especially digitization and automation, play a major role in shaping the future world. Technological innovations promise the transformation of the world we live in all its dimensions. However, in order for the benefits of innovation to be adequately exploited, it is necessary for us as a society to adapt to the coming changes. We must also keep in mind that these changes come at a time previously marked by uncertainty, turbulent changes and hyper competitiveness. The development and implementation of new technologies in business is motivated by a number of technical and economic reasons: improving the quality of finished products (machining, etc.), increasing productivity and reducing the share of work (assembly process), increasing the degree of homogeneity of product quality in all production processes related to the application of robotic technology, increasing the level of safety, reducing labor engagement in routine and reproducible processes, minimizing total production costs and maintenance costs of the device in the production process, all with the purpose of adequate responses to competition challenges and increasingly stringent customer requirements. Although the concept of Industry 4.0 is already widely used in developed countries, it is a relatively new concept in the Western Balkans, including Bosnia and Herzegovina. Most company managers understand the benefits of "smart" production and are familiar with new trends in the industry, intend to gradually introduce smart solutions, methods and technologies, and only a small number of companies in Bosnia and Herzegovina currently implement the concept of Industry 4.0. The paper presents the results of research on the application of Industry 4.0 technologies in all branches of the economy in Bosnia and Herzegovina and especially the representation of Industry 4.0 in small, medium and large enterprises. Detection of awareness of certain groups about the concepts of Industry 4.0 was performed, and the research method itself is based on an online survey.

Darko Šunjić, S. Buljan

Explosive forming appeared at the end of the 19th century as unconventional technology that provides new methods to get workpieces with bigger dimensions and complex geometries. As a source of energy this technology uses explosives. Explosive, as such, is relatively inexpensive and theoretically with it, it is possible to get any amount of energy that is needed. Explosive forming is used with other technologies such as deep drawing, expansion of pipes, welding etc. One of the main explosive characteristics is the velocity of detonation that can be determined, inter alia, with the Dautrich method. This paper clarifies the method and gives a case study with explosive Vitezit 20.

Franko Puh, Z. Jurković, M. Perinić, M. Brezocnik, S. Buljan

Optimizacija parametara obrade tokarenja s vise kriterija kvalitete uporabom Grey relacijske analize Izvorni znanstveni clanak Optimizacija procesa obrade je neophodna za postizanje vece produktivnosti i visoke kvalitete proizvoda kako bi ostali tržisno konkurentni. Ovaj rad istražuje vise-kriterijsku optimizaciju procesa tokarenja s optimalnom kombinacijom parametara obrade koji osiguravaju minimalnu hrapavost povrsine (Ra) s maksimalnim ucinkom uklanjanja materijala (MRR) uporabom Grey-based Taguchi metode. Razmatrani parametri obrade tokarenjem su brzina rezanja, posmak i dubina rezanja. Primjenom Taguchijevog L9 (3 4 ) ortogonalnog plana provedeno je devet eksperimenata te je koristena Grey relacijska analiza kako bi se rijesio visekriterijski problem optimizacije. Temeljem vrijednosti Grey relacijskog stupnja utvrđene su optimalne razine parametara. Signifikantnost parametara na sveukupne kriterije kvalitete procesa tokarenja ocijenjena je analizom varijance (ANOVA). Optimalne vrijednosti parametara dobivene tijekom istraživanja potvrđene su verifikacijskim eksperimentom. Kljucne rijeci: ANOVA; Grey relacijska analiza; Taguchijeva metoda; tokarenje; visekriterijska optimizacija

M. Jurković, Z. Jurković, M. Obad, S. Buljan, Edin Mustafić

The fundamental basis for implementation of reengineering is: experimental measurement of forces and torques on the rollers-tools production line for profile sheet metal forming. The paper presents the experiments of measuring forces and torques, modeling and simulation in the aim of redesigning the process of sheet metal forming, selecting of the optimal process of sheet metal forming for each forming module and totally for the production line and increasing productivity on production lines. In the experimental research forces and torques were measured on the rollers of forming modules for profile forming of sheets for different values of the input parameters of the process: material type σm, sheet thickness s and sheet width b. Based on the experimental results mathematical models were defined, which enabled the analysis and implementation of reengineering the production system.

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