Electrospark deposition for die repair

The electrospark deposition is a process for surfacing of hard metal alloys, e.g. carbides and stellites, on the surfaces of new or old machine elements. In this process, a high current is conducted through an oscillating electrode and a substrate for a very short period of time. In the paper, the process is described and the thickness of deposited layer, chemical composition, dilution rate and the layer roughness are determined

Nanošenje električnom iskrom za popravak alata

The electrospark deposition is a process for surfacing of hard metal alloys, e.g. carbides and stellites, on the surfaces of new or old machine elements. In this process, a high current is conducted through an oscillating electrode and a substrate for a very short period of time. In the paper, the process is described and the thickness of deposited layer, chemical composition, dilution rate and the layer roughness are determined.Nanošenje električnom iskrom postupak je za navarivanje tvrdih metalnih slitina, npr. karbida i stelita, na površinu novih ili starih elemenata strojeva. U tom postupku visoka struja provodi se kroz oscilirajuću elektrodu i supstrat na vrlo kratko vrijeme. U članku opisan je postupak i određeni su debljina nanesenog sloja, kemijski sastav, stupanj miješanja i hrapavost sloja

Izrada dvoplastnog alata za ubrizgavanje termoplasta postupkom zavarivanja

The article presents the technology of deposit cladding different materials, using the injection molds for thermoplastic as a case study. The aim of the study is to surface weld to the working surface of the mold a different material with corresponding physical properties. Steel (1.1141) and a copper alloy were used as the base, onto which different materials were surface-welded. Tungsten inert gas (TIG) welding was employed to make molds inserts. An analysis of cross-sectioned specimens was made by optical microscopy, and chemical and hardness profiles were measured too. The thermal conductivity of base and cladded layer was also tested. Finally, a thermal fatigue test was employed to investigate the thermal fatigue properties of such surfaces.U članku predstavljena je tehnologija navarivanja različitih materijala na primjeru alata za ubrizgavanje termoplasta. Cilj istraživanja je navarivanje drukčijeg materijala s odgovarajućim fizikalnim svojstvima na radnu površinu alata. Ulošci alata izrađeni su postupkom zavarivanja volframovom elektrodom uz zaštitu inertnog plina (TIG). Kao osnova na koju su navareni različiti materijali korišteni su čelik (1.1141) i bakarna slitina. Poprečni presjek uzoraka analiziran je optičkim mikroskopom, izmjereni su i kemijski profil i profil tvrdoće. Testirana je i toplinska provodljivost osnovnog i navarenog materijala. Na kraju je izvršen i test termičkog zamora u svrhu istraživanja svojstava termičkog zamora takvih površina

Computing the common zeros of two bivariate functions via Bézout resultants

The common zeros of two bivariate functions can be computed by finding the common zeros of their polynomial interpolants expressed in a tensor Chebyshev basis. From here we develop a bivariate rootfinding algorithm based on the hidden variable resultant method and Bézout matrices with polynomial entries. Using techniques including domain subdivision, Bézoutian regularization, and local refinement we are able to reliably and accurately compute the simple common zeros of two smooth functions with polynomial interpolants of very high degree (≥ 1000). We analyze the resultant method and its conditioning by noting that the Bézout matrices are matrix polynomials. Two implementations are available: one on the Matlab Central File Exchange and another in the roots command in Chebfun2 that is adapted to suit Chebfun’s methodology

The manufactoring of a two–layered injection mold by welding

The article presents the technology of deposit cladding different materials, using the injection molds for thermoplastic as a case study. The aim of the study is to surface weld to the working surface of the mold a different material with corresponding physical properties. Steel (1.1141) and a copper alloy were used as the base, onto which different materials were surface-welded. Tungsten inert gas (TIG) welding was employed to make molds inserts. An analysis of cross-sectioned specimens was made by optical microscopy, and chemical and hardness profiles were measured too. The thermal conductivity of base and cladded layer was also tested. Finally, a thermal fatigue test was employed to investigate the thermal fatigue properties of such surfaces