Research on energy efficiency of pneumatic cylinder for pneumatic vehicle motor

Compressed gas is relatively expensive source of energy. When compressed gas is used for propelling of pneumatically driven vehicle, efficient gas utilization is favoured. Design and control strategy of pneumatic cylinder, with the emphasis on effective energy conversion is being discussed in this paper. Mathematical model, results of computer simulation and experimental work are provided and discussed. Experimental research is performed on the competition vehicle, equipped with pneumatically driven piston motor and instrumented. Relative significance of various geometric and control parameters of pneumatic cylinder on efficiency of energy conversion is presented

DIG-MAN: Integration of digital tools into product development and manufacturing education

General objectives of PRODEM education. Teaching of product development requires various digital tools. Nowadays, the digital tools usually use computers, which have become a standard element of manufacturing and teaching environments. In this context, an integration of computer-based technologies in manufacturing environments plays the crucial and main role, allowing to enrich, accelerate and integrate different production phases such as product development, design, manufacturing and inspection. Moreover, the digital tools play important role in management of production. According to Wdowik and Ratnayake (2019 paper: Open Access Digital Tool’s Application Potential in Technological Process Planning: SMMEs Perspective, https://doi.org/10.1007/978-3-030-29996-5_36), the digital tools can be divided into several main groups such as: machine tools and technological equipment (MTE), devices (D), internet(intranet)-based tools (I), software (S). The groups are presented in Fig. 1.1. Machine tools and technological equipment group contains all existing machines and devices which are commonly used in manufacturing and inspection phase. The group is used in physical shaping of manufactured products, measurement tasks regarding tools and products, etc. The next group of devices (D) is proposed to separate the newest trends of using mobile and computer-based technologies such as smartphones or tablets and indicate the necessity of increased mobility within production sites. The similar need of separation is in the case of internet(intranet)-based tools which indicate the growing interest in network-based solutions. Hence, D and I groups are proposed in order to underline the significance of mobility and networking. These two groups of the digital tools should also be supported in the nearest future by the use of 5G networks. The last group of software (S) concerns computer software produced for the aims of manufacturing environments. There is also a possibility to assign the defined solutions (e.g. computer programs) to more than one group (e.g. program can be assigned to software and internet-based tools). The main role of tools allocated inside separate groups is to support employees, managers and customers of manufacturing firms focused on abovementioned production phases. The digital tools are being developed in order to increase efficiency of production, quality of manufactured products and accelerate innovation process as well as comfort of work. Nowadays, digital also means mobile. Universities (especially technical), which are focused on higher education and research, have been continuously developing their teaching programmes since the beginning of industry 3.0 era. They need to prepare their alumni for changing environments of manufacturing enterprises and new challenges such as Industry 4.0 era, digitalization, networking, remote work, etc. Most of the teaching environments nowadays, especially those in manufacturing engineering area, are equipped with many digital tools and meet various challenges regarding an adaptation, a maintenance and a final usage of the digital tools. The application of these tools in teaching needs a space, staff and supporting infrastructures. Universities adapt their equipment and infrastructures to local or national needs of enterprises and the teaching content is usually focused on currently used technologies. Furthermore, research activities support teaching process by newly developed innovations. Figure 1.2 presents how different digital tools are used in teaching environments. Teaching environments are divided into four groups: lecture rooms, computer laboratories, manufacturing laboratories and industrial environments. The three groups are characteristic in the case of universities’ infrastructure whilst the fourth one is used for the aims of internships of students or researchers. Nowadays lecture rooms are mainly used for lectures and presentations which require the direct communication and interaction between teachers and students. However, such teaching method could also be replaced by the use of remote teaching (e.g. by the use of e-learning platforms or internet communicators). Unfortunately, remote teaching leads to limited interaction between people. Nonverbal communication is hence limited. Computer laboratories (CLs) usually gather students who solve different problems by the use of software. Most of the CLs enable teachers to display instructions by using projectors. Physical gathering in one room enables verbal and nonverbal communication between teachers and students. Manufacturing laboratories are usually used as the demonstrators of real industrial environments. They are also perfect places for performing of experiments and building the proficiency in using of infrastructure. The role of manufacturing labs can be divided as: • places which demonstrate the real industrial environments, • research sites where new ideas can be developed, improved and tested. Industrial environment has a crucial role in teaching. It enables an enriched student experience by providing real industrial challenges and problems

Modifitseeritud lõikuriga raskesti töödeldavate materjalide pinnakvaliteedi parandamine viimistleval treimisel

One important challenge in engineering is the setting of dimensions and tolerances of the machine elements’ surfaces, which work together. The shape and position tolerances may increase the occurrence of failures and can lead to a decrease in the performance of machinery. Because of this, it is very important to achieve as stable as possible cutting process in order to get quality parts and extend the lifetime of the cutting tool to the maximum. Unfortunately by turning of complex products from hard-to-cut materials the stability may be lost, which leads to tool oscillations. This causes an increase in the cutting tool wear, reduces the lifetime of the machine actuators and reduces productivity. The cutting system components that most readily can be brought into vibration are the cutting tool, the workpiece and the clamping equipment (Stahl, 2012). Vibrations and other sorts of unintended periodic movements are produced by variations in the contact forces between the workpiece and the cutting tool, these in turn are being produced by variations in cutting resistance or in cutting data. Vibrations of the cutting tool can take place in machining operations of most types, whatever the geometry and size of the workpiece may be (Schmitz & Smith, 2008). In turning of hard workpiece materials very high stresses act on the tool holder through the cutting tool. These stresses require the tool holder to have some specific properties such as high stiffness and its ability to absorb the energy generated during the cutting process. It is also important that the material cost of the tool holder is being taken into account because lower cost provides a competitive advantage for manufacturers. One aspect of improving the dynamic stability of the subsystem "tool" is the creation of damped tools with increased resistance. Specialized cutting tool holders help to shift the stable operating regions to avoid chatter vibrations, increase the manufacturing precision and productivity of machine components. Consequently, the aim of the work was to focus on the utility effect of a cutting tool holder modified with alternate bars of different material structure in its construction. The different bars are made from rolled steel and have an anisotropic structure, which also has different mechanical properties. This construction is considered as a method to improve the cutting stability of the cutting tool and helps to suppress the oscillations in the finishing turning of hard to cut materials.Üheks oluliseks probleemiks kvaliteedi tagamisel on seada mõõtmed ja tolerantsid masina elementide pindadele, mis peavad koos töötama. Kõrvalekalle asendi- ja kujuhälvetest võib suurendada rikete esinemist ning võib kaasa tuua enneaegse masina purunemise. Seetõttu on väga oluline saavutada võimalikult stabiilne lõikeprotsess, et oleks võimalik toota kvaliteetseid masina elemente ja pikendada ka maksimaalselt lõikeinstrumendi eluiga. Kahjuks võib raskesti töödeldavatest materjalidest detailide lõikamisel stabiilsus kaduda, mille tagajärjel tekib vibratsioon. See põhjustab lõikeinstrumendi suurenenud kulumist ja vähendab masinate eluiga ning tootlikkust. Lõikesüsteemi osad, mis kõige lihtsamalt võivad lõikeprotsessis vibreerida, on: lõikeinstrument, töödeldav detail ja kinnitusseadmed (Stahl, 2012). Vibratsioon tekib kõige sagedamini detaili ja lõikeinstrumendi kontaktjõudude vahel, need omakorda on põhjustatud materjali struktuuri omadustest ja lõikerežiimist. Lõikeinstrumendi vibratsioon võib esineda mis tahes töötlusoperatsiooni käigus olenemata töödetava detaili geomeetriast või suurusest (Schmitz & Smith, 2008). Raskesti töödeldavatest materjalidest detailide treimisel mõjuvad suured jõud lõikeinstrumendi hoidikule, mille tõttu on oluline, et hoidikul oleks vastavad omadused, nagu suur jäikus ning võime summutada lõikeprotsessi ajal tekkinud energiat. Selle juures on oluline, et hoidiku maksumus oleks optimaalne, sest odavam hind annab tootjale konkurentsieelise. Sellest lähtuvalt oli doktoritöö eesmärgiks välja töötada vibratsioone summutav lõikeinstrumendi hoidik, mis võimaldaks vähendada esinevaid vibratsioone raskesti töödeldavate materjalide viimistleval treimisel ning aitaks parandada töödeldavate detailide kvaliteeti ja tootlikust. Tulenevalt eesmärgist oli esimeseks ülesandeks analüüsida lõikeprotsessi olemust ning vibratsioonide tekke põhjuseid. Lahenduse väljatöötamisel anti ülevaade vibratsioonide summutamise teooriast ning lõikeprotsessi olemusest. Analüüs näitas, et antud protsess omab lainelist olemust struktuuri igal tasemel. Seetõttu on põhjendatud eelduseks, et plastse deformatsiooni laineline olemus on vibratsioonide peamiseks allikaks treimise protsessis. Väljatöötatud meetod stabiilsuse suurendamiseks treimisel põhineb valtsitud terase anisotroopsetel omadustel. Tegemist on passiivse vibratsiooni summutamise lahendusega, kus vibratsiooni lainete hajumise põhjustab terakeha sisse paigutatud varraste kokkupuute pindade üksteise vastu hõõrumine. Antud lõikeinstrumendi hoidikuga on läbi viidud katsetused, kus on uuritud sellega töödeldud detailide pinnakaredust ning esinevaid vibratsioone. Hoidik on arendatud kasutamiseks CNC tüüpi treipinkides viimistlevaks töötlemiseks, kuid seda on võimalik kasutada ka manuaalsetes pinkides. Katsetustel saadud andmete põhjal on analüüsitud hoidiku kasutamisega saadud pinnakvaliteedi paranemist võrreldes originaalhoidikuga. Arendatud hoidik võimaldab muuta stabiilse lõikamise piirkonda ning aitab summutada tekkivaid vibratsioone, mis omakorda parandab töötlemise täpsust ja suurendab tootlikust

ENGINEERING FOR RURAL DEVELOPMENT IMPACT OF ETHANOL ON FUEL INJECTION PUMP OF DIESEL ENGINE

Abstract. In general, it is not purposeful to use ethanol as diesel engine fuel, because it causes problems in the fuel system. When using ethanol in a high-pressure pump, one common problem is the rapid wear or jamming of the plunger work surfaces. These problems arise due to the physical and chemical properties of ethanol. In order to study the wear-and-tear and work parameters of the pump, a test was performed with a used high-pressure pump. The selection of this pump was based on the average operation period of a tractor, in the case of machinery already used in agriculture. This work provides the test data acquired by using bioethanol in a highpressure pump and the analysis of the results obtained. Keywords: diesel engine, high-pressure pump, bioethanol, work surface. Introduction The research of potential uses for alternative fuels is becoming more popular worldwide. Various biofuels, alcohol fuels, biogas, and plant oils are used as motor fuels in several countries. The problem with using biofuels consists in the impact of their physical-chemical properties on the fuel supply system. One of such biofuels is bioethanol. Bioethanol is a prospective and widely used alternative fuel, which is used as motor fuel in many countries, such as the USA, Brazil, Germany, and Sweden [1; 2]. Due to its physical-chemical properties, bioethanol is mostly used in spark ignition engines. Namely, the auto-ignition temperature of ethanol is too high to be used in regular compression-ignition engines. In order to ignite ethanol in the compression-ignition engine, it is necessary to increase the pressure ratio, which results in increased pressure and temperature in the engine cylinder. Besides that the use of ethanol in diesel engine fuel-supply systems is complicated, because the lubricating properties and viscosity of ethanol are significantly lower than in diesel fuel. Another problem arises from the water content in the fuel, which causes corrosion The article examines the impact of 94.6 % bioethanol on the precise working components of diesel supply equipment. A closer look is given to the technical condition of plunger pairs and injectors of the in-line fuel-injection pump before and after operating on ethanol. The article also includes the study of the impact of ethanol on the geometry of the plunger work surfaces and on the changes in section capacity of the fuel injection pump. The aforesaid information is analysed and an evaluation of the impact of ethanol on fuel-supply equipment is provided. The results are gained by means of a fuel-injection pump test bench, where fuel-supply equipment was operated for 100 hours and the test liquid was 94.6 % bioethanol

Torrefaction of Agricultural and Wood Waste: Comparative Analysis of Selected Fuel Characteristics

Abundant biomass is a potential energy source. However, it possesses several challenges when considered for energy applications. Torrefaction, a thermal pretreatment process can improve the properties of biomass as energy source. This study focused on comparing effect of torrefaction operating parameters on agricultural and wood wastes properties as fuel. The physiochemical properties, composition, moisture-biomass interaction and ash melting behavior were determined. The result show that higher torrefaction temperature and longer residence time increased lignin content, reduced hemicellulose and cellulose content. The moisture uptake of torrefied biomass was reduced in the range 2.47–9.94% compared with raw biomass depending on torrefaction temperature that indicate torrefied biomass was more hydrophobic than raw biomass. The moisture adsorption isotherm curve shows type II isotherm based on the Brunauer-Emmett-Teller’s (BET) classification and was best described by the Oswin model. In addition, torrefaction treatment showed significant influence on the melting behavior of the biomass ash. Especially for agricultural wastes, the fouling tendency shifted from serious range to low range with torrefaction treatment. Torrefaction showed promise for improving fuel characteristics of the studied biomass