Plitko gravurno kovanje s aspekta mikrooblikovanja

doctoral thesis

• Title (english): Microforming approach to coining technology
• Author: Zdenka Keran
• Mentor: Miljenko Math (mentor)
• Committee member: Franjo Cajner (predsjednik povjerenstva)
• Committee member: Miljenko Math (član povjerenstva)
• Committee member: Bojan Jerbić (član povjerenstva)
• Committee member: Toma Udiljak (član povjerenstva)
• Committee member: Branko Grizelj (član povjerenstva)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2010-09-23, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering; Production Mechanical Engineering
• Universal decimal classification (UDC): 621 - Mechanical engineering. Nuclear technology. Machinery

Abstract

U radu je provedena eksperimentalna i numerička analiza procesa plitkog gravurnog kovanja s aspekta mikrooblikovanja. To je novi pristup rješavanju problema oblikovanja proizvoda malih dimenzija koji uzima u obzir utjecaj veličine kristalnog zrna na parametre procesa. Izvršena su mjerenja elastičnog povrata materijala rondele početne visine 2 mm za tri različite veličine kristalnog zrna i to kod slobodnog kovanja i kovanja u gravuri. Mjerena je sila oblikovanja potrebna za zadovoljavajuće popunjavanje gravure ukovnja kod istih veličina zrna. \Načinjena je i numerička analiza promjene koeficijenta kontaktnog trenja također za različite veličine kristalnog zrna. Radom je pokazano kako se prilikom plitkog gravurnog kovanja javlja značajna razlika u ponašanju materijala obratka kod različitih veličina kristalnog zrna te oprečno ponašanje parametara procesa prilikom slobodnog kovanja i kovanja u gravuri. Time je proces plitkog gravurnog kovanja nesumnjivo svrstan u procese mikrooblikovanja. Numeričkom analizom dobivena je teorijska zavisnost promjene veličine kontaktnog trenja obzirom na promjenu veličine kristalnog zrna kod specifičnog slučaja slobodnog kovanja.

Abstract (english)

The work presents an experimental and numerical analysis of coining process in terms of microforming. This is a new approach to solving the problems of small-sized products design that takes into account the influence of crystalline grain size on the process parameters. Measurements of elastic springback were made on roundels which initial height is 2 mm. This was done for three different grain sizes and also for the open and closed die forging processes. The force required for the satisfactory die filling was measured at the same grain sizes. A numerical analysis of friction coefficient changes was also made for different sizes of crystal grains. The work showed that during coining process a significant difference in the behaviour of workpiece material of different grain sizes appears and also the opposite behaviour of process parameters during open and closed die forging. This behavior classifies coining process into the group of microforming processes without any doubt. Numerical analysis showed theoretical friction coefficient dependence on grain size changes in speciffic case.

• Keywords: mikrooblikovanje; plitko gravurno kovanje; teorija dislokacija; veličina kristalnog zrna; elastični povrat; sila oblikovanja; ukupna deformacija
• Keywords (english): microforming; coining; dislocation theory; grain size; elastic springback; forming force; total deformation
• Language: croatian
• URN:NBN: urn:nbn:hr:235:051559
• Study programme: Title: Mechanical Engineering and Naval Architecture; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje tehničkih znanosti (doktor/doktorica znanosti, područje tehničkih znanosti)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2020-06-19 12:47:21