Izračun livarskih procesov za ulitek dela reduktorja iz sive litine z lamelnim grafitom : diplomsko delo

Ceraj, Nik Kristjan (author), Mrvar, Primož (mentor), Petrič, Mitja (comentor)

V svoji diplomski nalogi sem ugotavljal, zakaj pride v livarni LIGO.doo, pri ulivanju ulitka AUMA SQ 07 V1, ki se uporablja za del reduktorja, do napak posedanja in krčilne poroznosti. Ulitek se uliva iz sive litine z lamelnim grafitom v formo iz bentonitne peščene mešanice. Zaradi velikega nagnjenja določenega mesta ulitka do napake posedanja je izmet zelo velik, izdelava krožne litine pa je potratna s stališča dela in energije. Zato je bilo potrebno ulivno napajalni sistem optimizirati tako, da bi zmanjšali delež izmeta. Najprej sem v livarni mesto na ulitku, kjer se je najpogosteje pojavljala napaka posedanja analiziral z optičnim mikroskopom. Nato smo na TC livarstvu naredili izračun livarskih procesov pri ulivanju tega ulitka s pomočjo računalniške simulacije. Ugotovili smo, da je glavni vzrok napake posedanja prevelik modul točno pod mestom, kjer se napaka pogosto pojavlja. Večji kot modul kot ima telo, počasneje se ohlaja. To pomeni, da se to mesto na ulitku strdi zadnje. Idealno bi pa bilo, da bi se zadnji strdil napajalnik. Do posedanja in poroznosti torej pride, ker se prekine tok taline iz napajalnika v ulitek, ko del ulitka s prevelikim modulom še ni strjen in nastopa krčenje med ohlajanjem. Problem smo rešili z drugačno konstrukcijo napajalnika, ki je bil sposoben dlje časa napajati ulitek, saj je imel ta večji modul kot prejšnji napajalnik. Spustili smo tudi livno temperaturo, da smo tako zmanjšali krčenje med ohlajanjem litine.

• Language: Slovenian
• Keywords: siva litina, lamelni grafit, posedanje, modul ulitka
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: [N. K. Ceraj]
• Year: 2022
• Number of pages: XI, 33 f.
• PID: 20.500.12556/RUL-141309
• UDC: 669
• COBISS.SI-ID: 131433731
• Publication date in RUL: 28.09.2022

CERAJ, Nik Kristjan, 2022, Izračun livarskih procesov za ulitek dela reduktorja iz sive litine z lamelnim grafitom : diplomsko delo [online]. Bachelor’s thesis. Ljubljana : N. K. Ceraj. [Accessed 1 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=141309

Secondary language

• Language: English
• Title: Calculation of casting processes for part of reductor from gray cast iron : diploma work

Abstract

In my diploma thesis, I found out why in the foundry LIGO.doo, during the casting of the casting AUMA SQ 07 V1, which is used as a part of the reductor, settling errors and shrinkage porosity occur. The casting is cast from gray cast iron with lamellar graphite into a form of bentonite sand mixture. Due to the large inclination of a certain place of the casting to the settling error, the ejection is very large, and the production of circular cast iron is wasteful from the point of view of work and energy. Therefore, the inflow feed system had to be optimized to reduce the ejection fraction. First, I analyzed the place on the casting in the foundry, where the most common settling error occurred, with an optical microscope. Then, at TC Livarstvo, we made a calculation of casting processes in the casting of this casting with the help of computer simulation. We found that the main cause of the settling error is an oversized module just below where the error often occurs. The larger the modulus than the body has, the slower it cools. This means that this spot on the casting hardens last. Ideally, however, the feeder should harden last. Settling and porosity therefore occur because the flow of melt from the feeder to the casting is interrupted when a part of the casting with an oversized module has not yet solidified and shrinkage occurs during cooling. We solved the problem with a different design of the feeder, which was able to power the casting for a longer time, as it had a larger module than the previous power supply. We also lowered the casting temperature to reduce shrinkage during the cooling of the cast iron.

• Keywords: gray cast iron, lamellar graphite, settling, module of casting