Obrábění II

Tento učební text je určen zejména pro posluchače přednášek předmětu Obrábění. Předmět Obrábění (OBR 346-3003) je zaměřen na posluchače třetího ročníku bakalářského studia oboru strojírenská technologie, tedy pro studenty 5. semestru oboru B0715A270011 – Strojírenství, specializace Strojírenská technologie. Předmět má pod záštitou katedra Obrábění, montáže a strojírenské metrologie (kat 346), fakulty strojní VŠB–TUO. Pro studium tohoto předmětu se předpokládá, že student absolvoval předmět 346-3001 – Technologie obrábění. Učební text se snaží také doplňovat a rozšiřovat informace také k předmětům Technologie obrábění, Teorie obrábění, CAM systémy v obrábění a Počítačová podpora obrábění. Učební text je určen nejen pro studenty, kteří si zvolili zmiňovaný předmět Obrábění, ale také pro všechny zvídavé a nadšené strojaře prahnoucích po nových poznatcích v zajímavém a rychle rozvíjejícím se oboru technologie obrábění. Účelem této publikace je shrnutí pojmů, obecných zákonitostí, postupů a informací potřebných pro technology obrábění ve zkrácené formě podání. Skripta doplňují ústní výklad učiva na přednáškách Obrábění, proto zde nejsou detailní popisy prezentovaných obrázků, schémat a grafů.OstravaE-vyuk

A study of effects of changing the position of the tool axis against the machined surface

The article focuses on monitoring the machined surface after it has been machined with different milling strategies. Different milling strategies refer to milling whilst changing the tool axis relative to the surface after finishing the free form milling. The research focuses mainly on the geometric characteristics of the finished surface profile and residual stresses in the surface layer. The goal of the experimental work is to find an effective position of the tool axis, or an effective interval of the tool axis, in relation to the machined surface normal. Practical applications of the results are focused on finishing milling of complicated shape surfaces especially in the production of moulds and dies for the automotive and aerospace industries. The technology is based on the substitution of three-axis milling for multi-axis milling, i.e. mainly 5-axis simultaneous milling.Web of Science392463

Učinak brzine posmaka na trajnost i trošenje izmjenljivih pločica tijekom rezanja Ni-625

This paper deals with the process of cutting of nickel superalloy and selection of suitable cutting parameters for its easy and effective cutting. The experimental part proposes three exchangeable inserts and determines the effect of feed rate cutting parameter during machining on durability and wear of the cutting tool. Depending on selected cutting feed rate and the amount of wear of these exchangeable cutting inserts, the quality of turned surface is evaluated and height roughness parameters are determined. In closing we show our observations obtained while machining Inconel 625, determine the effect of feed rate on durability and wear of cutting inserts, evaluate and recommend practical steps, describe the mechanisms of cutting wedge wear, determine the durability of the tool and roughness of the turned surface.Rad se bavi postupkom rezanja super legure nikla i odabirom odgovarajućih parametara rezanja za njezino lako i učinkovito rezanja. U eksperimentalnom dijelu predlažu se tri izmjenljive pločice i određuje učinak parametra posmaka tijekom obrade na trajnost i trošenje reznog alata. Ovisno o izboru posmaka rezanja i količini trošenja tih izmjenljivih pločica, procijenjena je kvaliteta tokarene površine i određeni parametri visine hrapavosti. U završnom dijelu iznosimo opažanja do kojih smo došli tijekom obrade Inconel 625, određujemo učinak posmaka na trajnost i trošenje pločica, procjenjujemo i preporučujemo praktične korake, opisujemo mehanizme trošenja reznog klina, određujemo trajnost alata i hrapavost tokarene površine.Web of Science2416

Machining accurate holes with required roughness

The knowledge gained from the theoretical and practical tests in the production of precise openings has been utilized in a wide range of technologies from simple machine parts to complex schemes requiring accurate placement of individual parts. The topic here deals with the production of precise holes of required roughness according to the customer's requirements, it is a sealing of hydraulic cubes with a ball plug. The article examines the possibilities of existing technology, proposes the possibilities of using other tools or changes in the machining parameters, all using one machine tool. All theoretical knowledge has been verified by practical tests with the use of measuring instruments such as hardness meters. All output measurements were recorded in tables and graphs for more clear results and used in practice.Web of Science20192974296

Cutting tool wear monitoring with the use of impedance layers

The article deals with problems of cutting process monitoring in real time. It is focused on tool wear by means of impedance layers applied on ceramic cutting inserts. In the experimental part the cutting process is monitored using electrical resistance measurement. The results are compared and verified using the monitored cutting temperature and tool wear. The testing of impedance layers is reasonable mainly for cutting edge diagnostics. The width of this layer determines the wear allowance of tool wear (flank wear). Excessive wear causes a sharp reduction of this layer and thus a sharp increase in electrical resistance, which is a warning signal of the end of the cutting edge durability.Web of Science21364463

Cutting tool wear monitoring with the use of impedance layers

The article deals with problems of cutting process monitoring in real time. It is focused on tool wear by means of impedance layers applied on ceramic cutting inserts. In the experimental part the cutting process is monitored using electrical resistance measurement. The results are compared and verified using the monitored cutting temperature and tool wear. The testing of impedance layers is reasonable mainly for cutting edge diagnostics. The width of this layer determines the wear allowance of tool wear (flank wear). Excessive wear causes a sharp reduction of this layer and thus a sharp increase in electrical resistance, which is a warning signal of the end of the cutting edge durability.Web of Science21364463

Cutting tool wear monitoring with the use of impedance layers

The article deals with problems of cutting process monitoring in real time. It is focused on tool wear by means of impedance layers applied on ceramic cutting inserts. In the experimental part the cutting process is monitored using electrical resistance measurement. The results are compared and verified using the monitored cutting temperature and tool wear. The testing of impedance layers is reasonable mainly for cutting edge diagnostics. The width of this layer determines the wear allowance of tool wear (flank wear). Excessive wear causes a sharp reduction of this layer and thus a sharp increase in electrical resistance, which is a warning signal of the end of the cutting edge durability.Web of Science21364463

Cutting tool wear monitoring with the use of impedance layers

The article deals with problems of cutting process monitoring in real time. It is focused on tool wear by means of impedance layers applied on ceramic cutting inserts. In the experimental part the cutting process is monitored using electrical resistance measurement. The results are compared and verified using the monitored cutting temperature and tool wear. The testing of impedance layers is reasonable mainly for cutting edge diagnostics. The width of this layer determines the wear allowance of tool wear (flank wear). Excessive wear causes a sharp reduction of this layer and thus a sharp increase in electrical resistance, which is a warning signal of the end of the cutting edge durability.Web of Science21364463

Accuracy of machine tools

The accuracy of milling centre geometry is a basic condition for successful application in practice. Users of modern centres have to deal with the issue of measuring accuracy using in the production program. The desired results are achieved by careful preparation both before and during adjustment operations. These rules apply to all applications for new machines, but also to machines after collision or after handling older machines. The geometrical accuracy of the machine begins at the design stage, when the emphasis must be placed on the precision of production of parts and groups with the precise assembly of new machines. Even the best adjustment or alignment of the machine is not valid if the company orders a poor quality machine that does not meet the required characteristics both in design and quality. Such a poorly selected machine guarantees frequent interventions by technicians to ensure at least the minimum required tolerance.Web of Science20203836383

Cutting tool life tests of ceramic inserts for car engine sleeves

Ovaj članak je usredotočen na eksperimentalno određivanje trajnosti alata za indeksiranje keramičkih reznih uložaka. Postavljen je kriterij trošenja alata VBBmax = 0,6 mm (sukladno ISO 3685) ili 30 komada obrađenih tuljaka. Kada je postignut barem jedan od ovih parametara, ispitivanje je zaustavljeno i procijenjeno. Ispitivane su dvije vrste reznog materijala uz pomoć tvrtke Saint Gobain Advanced Ceramics s.r.o. – ZTA 7 NI i D 250. Pratili smo njihovu trajnost kod istih parametara obrade. Eksperimenti su izvedeni na alatnom stroju – CHEMNITZ NILES N22. Obrađivani materijal bio je lijevano željeza 25P koje se koristi za motore automobila. Trošenje alata praćeno je za svaki peti obrađeni tuljak. Mjerena je mikrogeometrija nakon ispitivanja trošenja alata na svakom petom tuljku. Cilj je bio odrediti aritmetičku toleranciju Ra profila, najveću visinu Rz profila i vanjski promjer D. Mjerenje je provedeno četiri puta, aritmetička sredina je izvedena naknadno i prikazana je u tablicama.This article is focused on the experimental determination of tool life tests for indexable ceramic cutting inserts. The set criterion of tool wear was VBBmax = 0,6 mm (in accordance with ISO 3685) or 30 pieces of machined sleeves. After at least one of the mentioned parameters was achieved, the tests were stopped and evaluated. Two types of cutting material by Saint Gobain Advanced Ceramics s.r.o. Company – ZTA 7 NI and D 250 were tested. We monitored their tool life at the same cutting parameters. The experiments were performed on machine tool – CHEMNITZ NILES N22. The machined material was the cast iron 25P mainly used for car engines. Tool wear was monitored on every fifth machined sleeve. Microgeometry was measured after tool wear test on each fifth sleeve. The aim was to determine the arithmetic tolerance of Ra profile, the greatest height of Rz profile and the external diameter D. The measurement was carried out four times; arithmetic average was performed subsequently as it is shown in the tables