Study of the influence of pulsating water jet technology on material surface

Import 14/02/2017Technologie vysokorychlostních kapalinových paprsků doznala v posledních třiceti letech nebývalého rozmachu a rozšířila se jako univerzální nekonvenční technologie do téměř všech průmyslových odvětví. Výzkum vlastností a chování kapalinových paprsků a jejich další vývoj však nadále probíhají se stejnou intenzitou. Jedním z nových směrů, kterým se výzkum ubírá, jsou pulzující kapalinové paprsky. Budoucí využití těchto paprsků se předpokládá ve stavebnictví a strojírenství, zvláště pak v automobilovém a leteckém průmyslu. Disertační práce se zabývá studiem vlivu pulzujícího vodního paprsku při jeho dopadu na povrch materiálu. Teoretická část se věnuje vývoji kapalinových paprsků, klasifikaci jednotlivých druhů a jich využití v komerční sféře. Jsou zde uvedeny jednotlivé části vysokotlakého řetězce, které jsou nutné pro generování pulzujícího vodního paprsku. V teoretické části je rovněž podrobně popsán princip působení pulzujícího vodního proudu na povrch obráběného materiálu včetně mechanismů porušování, které se celého procesu desintegrace účastní. Experimentální část obsahuje návrh a popis zkoušek porušování vybraných kovových materiálů (korozivzdorná ocel, hliníková slitina a měď) pulzujícím vodním paprskem včetně následného vyhodnocení pro jednotlivá měření. První část je věnována experimentálnímu stanovení erozních účinků pulzujícího paprsku, v další části je pak provedena analýza vlivu jednotlivých technologických faktorů paprsku na zkoumaný povrch pomocí tzv. plánovaného experimentu. Jako míra účinku pulzujícího paprsku na obráběný povrch byly zvoleny vybrané parametry drsnosti a objemový úběr materiálu.Last thirty years, technology of high speed liquid jets has gone through unprecedented expansion and it has been applied in almost all industrial sectors as a universal unconventional technology. However, the research into properties and behavior of liquid jets and their further development continue with the same intensity. Pulsating water jets represent one of new directions which the research focuses on. It is expected that these jets will be applied in the construction and mechanical engineering, most especially in the automotive and aviation industries. The thesis studies the effect of the pulsating water jet impacting the surface of a material. The theoretical part focuses on the development of liquid jets, classification of particular liquid jet types and their commercial application. Individual parts of the high pressure chain which are essential for the generation of pulsating water jet are presented. In addition, the principle of pulsating water jet impact on the surface of a machined material, including mechanisms of disintegration, is described in the theoretical part. The experimental part consists of the design and description of tests of disintegration of selected metal materials (stainless steel, aluminium alloy and copper) with the pulsating water jet, including consequent evaluation of individual measurements. The first part deals with experimental determination of erosive effects of the pulsating water jet. In the following part, effect of individual technological factors of the jet on the studied surface is analyzed using the so-called Design of Experiments. Particular roughness parameters and the volume of material removal were selected in order to determine the effect of the pulsating water jet on a machined material.345 - Katedra mechanické technologievyhově

Effects of continuous and pulsating water jet on CNT/concrete composite

This paper presents first results of the study of the resistance of carbon nanotube concrete composite (CNT/concrete composite) to the action of continuous and pulsating water jets. The experiments oriented at the determination of erosion effects of pulsating and continuous water jets impinging the surface of reference (concrete) and CNT/concrete composite samples were performed. Tested samples were characterized by X-ray powder diffraction and scanning electron microscope. Samples were exposed to pulsating and continuous water jets at various operating parameters. Erosion effects of pulsating and continuous jets were evaluated in terms of material removal rate. The possible influence of addition of CNTs to the concrete on its resistance to the action of continuous and pulsating water jets is discussed in the paper. The experiments proved that CNT/concrete composite exhibits higher resistance than reference concrete to the action of both pulsating and continuous water jet under the given testing conditions.Web of Science631058958

Erosion of metals by pulsating water jet

Cilj rada bio je utvrditi eroziju uzrokovanu pulsirajućim vodenim mlazom koji udara o površinu metalnog uzorka. Istražen je utjecaj ponovljenih djelovanja vodenih impulsa i utjecaja brzine (radnog tlaka) na eroziju metalne površine. Analiziran je i raspravljen razvoj erozijskog modela u odnosu na broj djelovanja. Utvrđeno je da se erozija uzrokovana opetovanim djelovanjem vodenih impulsa ​​javlja u tri faze. Faza erozije površine može se odrediti pomoću ponašanja karakteristika površine (kao što su Ra i Rz) s obzirom na broj djelovanja pulsirajućeg vodenog mlaza.The aim of the paper was to determine erosion effects of pulsating water jet impinging the surface of metal sample. The influence of repeated impacts of water pulses and impact velocity (operating pressure) on the erosion of metal surface was investigated. The development of erosion pattern with respect to number of impacts was analysed and discussed. It was found that erosion caused by repeated impacts of water pulses occurs in three stages. The stage of erosion of the surface can be determined by the behaviour of surface characteristics (such as Ra and Rz) with respect to number of impacts of pulsating water jet

Effects of pulsating water jet on aluminium alloy with variously modified surface

Rad se bavi određivanjem učinaka erozije pulsirajućeg vodenog mlaza koji udara na površinu uzoraka od aluminijske legure obrađenih različitim postupcima (grubo i fino glodanje, blanjanje i valjanje). Ispitivao se utjecaj početne topografije površine na završnu topografiju uzorka izloženog pulsirajućem vodenom mlazu. Analizirala se erozija površinskih slojeva u odnosu na brzinu kojom ih mlaz prelazi. Ustanovilo se da početna svojstva površine značajno utječu na završnu topografiju. Stupanj erozije površine određen je mjerenjem površinskog parametra Ra.The paper deals with the topic of the determination of erosion effects of a pulsating water jet impinging the surface of aluminium alloy samples treated by various techniques (rough and fine milling, planing and rolling). The influence of the initial surface topography on the final topography of the sample exposed to the pulsating water jet was investigated. Erosion of surface layers was analysed and discussed in relation to the traversing velocity of the jet. It was found that initial surface properties have a significant impact on the final topography. Degree of the surface erosion was determined by the measurement of the surface parameter Ra

Abrasive waterjet (AWJ) titanium tangential turning evaluation

The paper deals with abrasive waterjet titanium tangential turning. Titanium grade 3 with a diameter of 55 mm was used as an experimental material. Technological conditions of turning tests were the same by gradually changing value of traverse speed (vf = 1,5; 3; 4,5; 6; 7,5 mm·min-1). Experiment tests were performed by using continuous abrasive waterjet of pressure p = 400MPa, by rotation n = 60 rpm of workpiece. The abrasive particles (Barton Garnet) were fed to the waterjet in the amount of 0,4 kg·min-1. It was determined that acceleration of traverse speed did not increase the surface profile parameters.Web of Science53454053

Comparison of surface roughness quality created by abrasive water jet and CO2 laser beam cutting

Ovaj se rad bavi procjenom kvalitete površinske hrapavosti ostvarene abrazivnim vodenim mlazom i CO2 laserom, s obzirom na utjecaj odabranih tehnoloških parametara na završnu kvalitetu obrađenih površina. Glavni cilj ovih eksperimentalnih istraživanja bio je razmotriti uporabu obje tehnologije za rezanje materijala koji se teško režu. Eksperimenti prezentirani u radu provedeni su na uzorcima titana ASTM B265-99. Obrađene površine uzoraka mjerene su optičkim profilometrom. Nakon toga, proučene su odabrane topografske značajke. Dobiveni podaci su korišteni za usporedbu hrapavosti površina parametara Ra u različitim dubinama. Napravljena je usporedba obje tehnologije na temelju postignutih rezultata.This paper deals with an evaluation of the surface roughness quality created by abrasive water jet and by CO2 laser, in terms of influence of the selected technological parameters on the final quality of machined surfaces. The main objective of these experimental studies was to consider the use of both technologies for cutting of difficult to cut materials. Experiments presented in the paper were carried out on titanium ASTM B265-99 samples. The machined surfaces of samples were measured by an optical profilometer. Subsequently, selected topographical characteristics were studied. The obtained data were used for comparison of surface roughness parameters Ra in different depths. Based on achieved results the comparison of both technologies was made

Surface Integrity Evaluation of Brass CW614N after Impact of Acoustically Excited Pulsating Water Jet

AbstractPresented article is focused on surface integrity evaluation of brass CW614N form the sight of surface topography, structural changes in surface layers and strengthening character in subsurface layers after impact of acoustically excited pulsating water jet (PWJ). Surface topography was evaluated using optical profilometry. Structural changes in subsurface layer were observed based on mass material removal Δm [mg/s] and maximal depth of penetrance of PWJ hmax [mm]. Nano indentation measurement according to Berkovich were used to examination of strengthening character in subsurface layer. Disintegration of experimental samples was performed under constant technological conditions: hydraulic power of plunger pump Ph = 19kW; round nozzle diameter d = 1.6mm; feed speed rate v = 0.75mm/s; pressure of plunger pump p = 38MPa, stand-off distance of nozzle from target material z = 45mm; ultrasound frequency f = 20.29kHz and as variable factor was set power of ultrasound P on values 340, 360 and 380W. In terms of surface topography experimental investigation proved that PWJ under selected conditions is not suitable for precision machining. Evaluation of the surface characteristics indicates that the chemical composition has a significant effect on material weight loss Δm [mg/s] and a maximum depth of penetration of PWJ hmax [mm]. Evaluation of characteristics of subsurface layer was observed strengthened area with lower elasticity

On the preparation of precursors and carriers of nanoparticles by water jet technology

Uporaba vodenog mlaza velike brzine proširila se u mnoga područja ljudskog djelovanja zbog njegovih jedinstvenih svojstava. Uz već tradicionalne tehnološke postupke počinje se primjenjivati u usitnjavanju mineralnih čestica. U ovom se radu analizira mogućnost usitnjavanja čestica primjenom abrazivne glave za miješanje koja stvara abrazivni vodeni mlaz velike brzine koji udara u čvrstu okomitu metu od volfram karbida. Čestice filosilikata (tj. sloja silikata) dimenzija kako mikrona tako i submikrona dobivene su ovom metodom. Ovom se metodom izbjegava stvaranje sekundarnih strukturnih defekata suprotno mehaničkim metodama usitnjavanja čestica. Nekoliko tipova mika (muskovit, vermikulit i biotit) i sitnozrnati kaoliniti usitnjeni su primjenom tehnologije vodenog mlaza. Rad se također bavi mogućnostima daljnje promjene dimenzija zrna čestica silikata te korištenja tako pripremljenih čestica kao supstance ili nositelja nanočestica.High-velocity water jet expanded into many fields of human activity due to its unique properties. Besides already traditional technological processes it begins to find its way also to the comminution of mineral particles. The paper analyzes the possibility of particle comminution using an abrasive mixing head used to generate high-velocity abrasive water jet and an impact of the jet to the solid perpendicular target made from tungsten carbide. Phyllosilicate (i.e. layered silicate) particles of both micron and submicron sizes were made by this method. The method avoids the formation of secondary structural defects which is in contrast to mechanical methods of particles comminution. Several types of micas (muscovites, vermiculite and biotite) and fine-grained kaolinites were comminuted using high-velocity water jet technology. The paper also deals with the possibilities of further change of silicate particles grain size and of using such prepared particles as precursors or carriers of nanoparticles

Ekonomska usporedba rezanja materijala pomoću lasera, plazme i kisika

This paper compares three of the most common processes: laser, plasma and oxygen cutting in terms of economical point of view. It illustrates the introduction of thermal cutting methods into the manufacturing of the companies with an emphasis on their productivity. This comparison can be carried out only to a limited extent what is given by many factors.U članku se uspoređuju tri najčešća procesa: rezanje laserom, plazmom i kisikom s ekonomskog motrišta. Članak prikazuje uvođenje metoda toplinskog rezanja u proizvodnju poduzeća s naglaskom na njihovu produktivnost. Ova usporedba može se provoditi samo u ograničenom opsegu, što je dano pomoću mnogo faktora.Web of Science19481781

Comparison of the actual costs during removal of concrete layer by high-speed water jets

This paper describes the process of possible evaluation of costs of using high speed water jet technology for concrete removal methods. High speed water jet technology is a progressive technology of removing damaged concrete used in civil engineering since the 80's of 20th century. It has been changing and developing since that time. But there is little information in literature devoted to the economic evaluation of this technology. Detailed economic analysis is still missing. This paper aims to compare comprehensively in economic terms the costs of removing concrete using the technology of both continuous oscillating and pulsating oscillating water jets. The research was realized in cooperation with research institutions and industrial companies and was supported by state budget of the Czech Republic and from the European Union. The scheme of cooperation of the University, research institutions, industrial companies and government follows the Triple helix model