diplomsko delo
Gregorič Lugarič (Author), Mitja Petrič (Mentor)

Abstract

Vsak ulitek zaznamuje njegova kakovost, tako površinske kot volumske napake. Na te napake močno vpliva postopek litja. Gravitacijsko litje je eden od postopkov, ki se po navadi uporablja za večje ulitke, v nekaterih primerih pa tudi za relativno majhne. Ta tehnika litja poteka v enkratne ali večkratne forme. Pri enkratnih formah najpogosteje uporabljamo pesek z dodatkom gline in vode t. i. bentonitna peščena mešanica, ki jo pred litjem oblikujemo, po končanem ulivanju pa porušimo. Ulivni sistem pri gravitacijskem litju je sestavljen iz lijaka, razdelilnih kanalov, dovodnih kanalov ter samega ulitka. Masna razmerja in postavitev posameznih komponent drastično vpliva na končni ulitek, saj med samim ulivanjem vpliva na hitrost taline in način polnjenja livne votline. Posledice so razni oksidi v ulitku, ter površinske in volumske napake, predvsem poroznost. Da je temu tako, smo ulili ulitek v obliki plošče na tri različne načine po tri ponovitve. Ulitek je bil ploščica z dolžino 10 cm, širino 3 cm in višino 1 cm, ki je bila izdelana iz lesa. Iz enakega materiala smo izdelali tudi ostale elemente ulivnega sistema z različnimi preseki in dolžinami. Pri tem je zelo pomembno, da upoštevamo livarski naklon, ki nam omogoči odstranjevanje komponent modela iz forme. Zaradi velikosti ulitka smo dodali tudi dva napajalnika na skrajni konec ulitka, da smo se izognili nastanku poroznosti in vpliva le te na kakovost ulitka. Ulitek smo poslali na RTG, naredili upogibni test ter analizo prelomnih površin. Našo teorijo je najbolj potrdila analiza prelomnih površin, katera nam pove, da ima ulitek, ki je ulit z ne tlačnim ulivnim sistemom najmanj napak.

Keywords

gravitacijsko litje;ulivni sistem;formanje;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UL NTF - Faculty of Natural Sciences and Engineering
Publisher: [G. Lugarič]
UDC: 669
COBISS: 90388739 Link will open in a new window
Views: 225
Downloads: 25
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Other data

Secondary language: English
Secondary title: influence of different gating systems on quality of casting
Secondary abstract: Each casting is characterized by its quality, both surface and volume defects. These defects are strongly influenced by the casting process. Gravity casting is one of the processes that is usually used for larger castings, and in some cases for relatively small. This casting technique takes place in single use and permanent moulds. In single use moulds, sand with the addition of clay and water is most often used so called the bentonite sand mixture, which is formed before casting and after casting, is demolished. Casting system in gravity castings consists of a funnel, runner, gates and the casting itself. The mass ratios and placement of the individual components drastically affect final casting, as it affects the melt velocity and the way casting cavity is filled during casting. The consequences are various oxides in the casting, as well as surface and volume defect, especially porosity. To make this so, we poured plate – shaped casting in three different ways with three repetitions. The pattern was a tile with a length of 10 cm, a width of 3 cm and a height of 1 cm, which was made of wood. Other elements of the casting system with different cross-sections and lengths were also made of the same material. In doing so, it is very important to take into account the draft angle, which allows us to remove the components of the pattern from the mold. Due to the size of the casting, we also added two feeders to the far end of the casting to avoid the formation of porosity and its impact on the quality of the casting. The casting was sent for X-ray, a bending test and analysis of fracture surfaces were performed. Our theory is most confirmed by the analysis of fracture surfaces, which tells us that a casting cast with a non-pressure casting system has the fewest defects.
Secondary keywords: gravity casting;casting system;moulding;
Type (COBISS): High school thesis
Study programme: 0
Thesis comment: Univ. v Ljubljani, Naravoslovnotehniška fak., Oddelek za materiale in metalurgijo
Pages: XI, 33 f.
ID: 14040749