Utjecaj odvođenja čestica na aksijalnu silu pri bušenju kamena

master's thesis

• Title (english): The influence of chip evacuation on axial force at stone drilling
• Author: Hinko Fuš
• Mentor: Toma Udiljak (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2018-07-12, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Danas se najveći udio u postupcima obrade odvajanjem odnosi na obradu metala. U isto vrijeme, sve se više potiču istraživanja i razvoj tehnologije obrade nehomogenih materijala poput kamena i kompozita. Svojstva kod nehomogenih materijala nisu jednaka po cijelom volumenu promatranog dijela. Navedeni problem utječe na proces obrade te na samo trošenje alata. Na samom početku teorijskog dijela rada biti će objašnjen postupak izračuna snage, momenata i sila kod bušenja. Biti će prikazani mehanizmi i oblici trošenja alata koji se mogu pojaviti zbog različitih uvjeta u kojima se nalazi alat tijekom obrade. Opisat će se Taylor-ov model trošenja alata, zatim kako se definira postojanost oštrice alata, odnosno životni vijek alata i koji od modela se primjenjuje kod postupka bušenja. Objasnit će se koja je svrha sredstva za hlađenje, ispiranje i podmazivanje (SHIP) te koje sve vrste i načini dovođenja postoje. Na kraju teorijskog dijela biti će objašnjen postupak elektro-erozijske obrade žigom koji je potreban kod modifikacije komercijalnog svrdla za provedbu eksperimenta. U eksperimentalnom dijelu, objašnjen je postupak modifikacije komercijalnog svrdla s tvrdo lemljenom pločicom, na način da se kroz svrdlo izradi kanal koji omogućava ispuhivanje i hlađenje reznih oštrica svrdla tijekom procesa bušenja. Provodit će se bušenje različitih vrsta kamena s različitim parametrima obrade i stupnjem istrošenosti svrdla. Tijekom bušenja koristit će se komprimirani zrak za ispuhivanje i hlađenje reznih oštrica svrdla. Kod provođenja pokusa snimat će se signali sila rezanja i jakosti struja pogonskih motora te će se prema planu eksperimenta vršiti snimanje stražnje površine svrdla pomoću industrijske kamere. Na kraju će se usporediti dobiveni rezultati s rezultatima bušenja kamena bez upotrebe SHIP-a.

Abstract (english)

Today, the largest share in machining processes refers to metalworking. At the same time, working technologies of non-homogeneous materials such as stone and composites are increasingly being explored. The properties of non-homogeneous materials are not equal through the entire volume of the observed body and that problem affects the working process and the tool wear. In the first part of this paper, the methods of calculation of powers, moments, and forces at drilling will be explained. The mechanisms and different types of tool wear that may occur due to the different cutting conditions in which the tool is located during cutting process will be displayed. Taylor’s model of tool wear and how the tool life is defined will be described. The purpose of cutting fluids (cooling lubrication fluid, coolant), which types and ways of bringing the coolant exist will be shown. At the end of first part, the Sinker Electrical Discharge Machining (Sinker EDM, Ram EDM) process, which is needed for modifying a commercial drill bit for experiment, will be explained. The experimental section of this paper explains the method of modifying a commercial drill bit with a hard solder plate, in such way that through the drill a channel is created which allows the flow of cutting fluids during drilling. Drilling of different types of stones will be carried out with different process parameters and the different degree of tool wear. Compressed air will be used during drilling to help extract a chip from the inside of the bore and cool the cutting edge of drill bit. During the experiment, the signals of cutting forces and the current of the drive motors will be recorded. Also, according to the plan of the experiment, the flank face of drill bit will be photographed using an industrial camera. At the end, the obtained results will be compared with the results of the same drilling processes carried out without using a compressed air as cutting fluid.

• Keywords: bušenje; kamen; trošenje; svrdlo; elektroerozija; ispuhivanje; SHIP; sile rezanja
• Keywords (english): drilling; stone; tool wear; EDM; coolant; compressed air; cutting force
• Language: croatian
• URN:NBN: urn:nbn:hr:235:925334
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 22:27:04