Kinematic analysis of quick-return mechanism in three various approaches

Članak se bavi kinematičkom analizom Whitwordovog mehanizma koja je izvedena u tri različite metode. Suvremene metode su računalno potpomognute s posebnim softverom za analizu obrade, koji može simulirati ne samo gibanje mehanizma, već može odrediti i položaj, brzinu, ubrzanje, sile, momente te druge parametre u svakom trenutku vremena, ali je potrebna provjera i razumijevanje zakona mehanike. Cilj je kinematičke analize istražiti gibanje pojedinih komponenti mehanizma (ili njegovih važnih točaka) u ovisnosti o gibanju pobuđivača. Ovdje su opisani osnovni principi triju pristupa te prednosti i nedostaci prezentiranih rješenja. Dobiveni se rezultati mogu usporediti, ako su rabljeni isti ulazni parametri.The article deals with kinematic analysis of quick-return mechanism that is executed by three various methods. The modern methods are computer aided with the special software for analysis processing, which can simulate not only the motion of the mechanism, but can define the position, velocity, acceleration, forces, moments and other parameters at every moment of time, but verification and mechanics laws understanding are necessary. The goal of the kinematic analysis is to investigate the motion of individual components of mechanism (or its important points) in dependence on the motion of drivers. The article describes the basic principles of three approaches, as well as the advantages and disadvantages of presented solutions. The obtained results can be compared, if the same input parameters are used

Thermal and performance analysis of a gasification boiler and its energy efficiency optimization

The purpose of this study was to determine a method for multi-parametric output regulation of a gasification boiler especially designed for heating or for hot water heating in buildings. A new method of regulation is offered, namely more parametric regulation via proportional-integral-derivative (PID) controllers that are capable of controlling the calculated values of pressure, temperature and fan speed. These values of pressure, temperature and fan speed are calculated in a completely new way, and calculations of setpoints for determination of optimal parameters lead to an increase in boilers efficiency and power output. Results of measurements show that changes at the mouth of the stack draft due atmospheric influences occur in times with high intensity and high frequency, while power parameters, or boiler power output amplitudes and fan speed automatically "copy" those changes proportionally due to instantaneous fan speed changes. The proposed method of regulation of the gasification boiler power output according to the technical solution enables a simple, cheap, express and continuous maintenance of high power output at low concentrations of the exhaust gases of the gasification boilers from the viewpoint of the boiler user, as well as from the perspective of development and production it allows a continuous control monitoring of these parameters.Web of Science107art. no. 106

Design and realization of the pull strength measuring device for SMD

Diplomová práce se zabývá problematikou návrhu a realizace zařízení pro měření síly v tahu u povrchově montovaných součástek (SMD). Rozebírá teorii testování pájeného spoje na pevnost v tahu s důrazem na normu IEC 62137-1-3 a popisuje volbu jednotlivých komponent využitých na tvorbu mechanické konstrukce i elektrické části. Vyrobené, nebo inovované elektronické části byly: řídící systém, výkonový obvod pro krokový motor a komunikace měřícího zařízení TEST 321 s PC. Celý návrh je doplněn o simulace mechanického namáhání kritických částí pomocí programu ANSYS. V závěru jsou shrnuty nejdůležitější parametry zařízení.This thesis deals with the design and implementation of a device for measuring pull strength by surface mounted devices (SMD). It analyzes the theory of pull strength testing of solder joints with emphasis on standard IEC 62137-1-3 and describes the selection of components utilized to create mechanical construction and electrical parts. These electronic parts made or innovated in this work were control system based on microcontroler Atmega164P, power circuit for stepper motor and communication of measure equipment TEST 321 with PC. The whole design is complemented by simulation of mechanical stress to the critical components using ANSYS. The conclusion summarizes the most important parameters of this equipment.

Realization of hybrid integrated circuits leads for high-temperature applications

Bakalářská práce řeší možnosti realizace vývodů hybridních integrovaných obvodů pro vysokoteplotní aplikace. Popisuje jejich realizaci pomocí metody přímého osazení vývodu, tato metoda k jejich fixaci využívá pastu pro vodivý motiv. Dále popisuje volbu vhodného materiálu vývodu a teplotního profilu přetavení ve vsázkové a průběžné peci, následné odstranění oxidů z vývodů. Dále byla navržena metoda testování teplotní odolnosti realizovaných vývodů. V závěru uvádí metodu zvýšení mechanické odolnosti pomocí dielektrické pasty.Bachelor thesis deals with realization possibilities of hybrid integrated circuit terminals for high temperature applications. It describes the realization method of direct mounting of terminals, this method of fixation using the conductive paste for the thick film technology. It also describes the selection of suitable materials and the temperature profile in the reflow and muffle furnace and follow removal of terminal oxides. Furthermore, a method for testing of terminals thermal resistance was realized. In conclusion, the method shows increased mechanical strength with the using of dielectric paste.

Static and dynamic assessment of an outlook tower construction

Tato práce se zabývá statickou a dynamickou analýzou vyhlídkové věže. Jedná se o dřevěnou rozhledu v obci Bohdaneč. Pro dynamickou analýzu byl vytvořen podrobný výpočtový model v programu ANSYS. Statická analýza byla provedena v programu Scia Engineer. Oba programy využívají metodu konečných prvků. Pozornost byla věnována zatížení větrem dle Eurokódu 1, zatížení námrazou, výpočtu dynamického součinitele a odezvě na odtrhávání vírů. Práce obsahuje také posouzení vybraných částí konstrukce dle Eurokódů.This thesis deals with static and dynamic analysis of an lookout tower construction. For dynamic analysis a computational model in ANSYS software is created. Static analysis is performed by Scia Engineer software. Both of this software use finite element method. It is also focused on wind load determination by Eurocode 1, structural factor calculation, modal analysis and vortex shedding. Verification of selected parts according to Eurocodes is included.

Molecularly-limited fractal surface area of mineral powders

The topic of the specific surface area (SSA) of powders is not sufficiently described in the literature in spite of its nontrivial contribution to adsorption and dissolution processes. Fractal geometry provides a way to determine this parameter via relation SSA ~ x(D − 3)s(2 − D), where x (m) is the particle size and s (m) is a scale. Such a relation respects nano-, micro-, or macro-topography on the surface. Within this theory, the fractal dimension 2 ≤ D < 3 and scale parameter s plays a significant role. The parameter D may be determined from BET or dissolution measurements on several samples, changing the powder particle sizes or sizes of adsorbate molecules. If the fractality of the surface is high, the SSA does not depend on the particle size distribution and vice versa. In this paper, the SSA parameter is analyzed from the point of view of adsorption and dissolution processes. In the case of adsorption, a new equation for the SSA, depending on the term (2 − D)∙(s2 − sBET)/sBET, is derived, where sBET and s2 are effective cross-sectional diameters for BET and new adsorbates. Determination of the SSA for the dissolution process appears to be very complicated, since the fractality of the surface may change in the process. Nevertheless, the presented equations have good application potential.Web of Science62art. no. 44

Automatizovaný systém pro návrh technologických parametrů hydro-abrazivního dělení materiálu

The abrasive waterjet technology is used today mainly for cutting metal materials. However, it is possible to use this technology also for cutting non-metal materials like marble or other materials whose surface must comply with specific parameters. Cutting non-metal materials using the abrasive waterjet technology is quite rare at present and we can find it mainly in laboratories. The main reason can be complicated settings of technological parameters. Technicians working with these mechanisms can predict these parameters based on their previous experience. Without such experience or when using new materials they have to make a lot of experiments to find the right technological parameters. The main task of this paper is to show how to use modern small computers to apply the automated system for the prediction of necessary parameters for the abrasive water jet cutting system which is developed at our university. This automated system can be helpful especially for the technicians who works with the abrasive waterjet technology or it may be part of robotized workplaces in future.V dnešní době je technologie hydro-abrazivního paprsku (AWJ) užívána zejména pro dělení kovových materiálů. Avšak tuto technologii je možné také využít pro dělení nekovových materiálů např. mramor nebo jiných materiálů, u kterých je důležité získat povrch s určitými parametry. Využití této technologie pro dělení nekovových materiálů je v dnešní době zatím ojedinělé, protože nastavení technologických parametrů je velice komplikované. Technici, kteří pracují s tímto zařízením, obvykle nastavují technologické parametry podle předchozích zkušeností. Pokud však nemají předchozí zkušenosti nebo pracují s novým materiálem, musí provést mnoho testů, tak aby byli schopni nalézt odpovídající technologické parametry. Článek je zaměřen na seznámení s automatizovaným systémem pro návrh technologických parametrů technologie AWJ a využití malých počítačových systémů. Tento automatizovaný systém je použitelný zejména pro techniky pracující s technologii AWJ a nebo v budoucnu může být součástí robotizovaných pracovišť v dolech

Physico-mechanical properties and electrical conductivity of conductive plastic materials

The paper deals with the research of variety of non-standard samples of plastic material made by injection moulding. The samples were made of conductive plastic material (LNP Stat-kon Compound ZX05009). Brown Corundum F24 was used for blasting under different pressures. This conductive plastic material can be applied as a plastic electrode, it is therefore possible to make measurements and examination of electrical conductivity. The experiment is used in order to establish the extent, to which the pressure used at blasting measurably affects the electrical conductivity of plastic electrode.Web of Science51215215

Statistical evaluation of impact of technological factors on surface texture of WPC composites

The paper aims at evaluating the impact of technological parameters of a drilling process on the parameter of surface roughness Rz (maximum height of roughness profile) of wood-based material (WPC – Wood Plastic Composite). During drilling with tools 3.0, 5.0 and 7.0 mm in diameter, the spindle speed nc and feed rate f were changed. The evaluation of statistical significance was performed using the ANOVA mathematical tool (two-way with repetition). Using a simple conversion, it is possible to assess which of the set parameters affects the final surface quality, which serves as supporting information for the work of an engineer.Web of Science52332932

Proposition of a solution for the setting of the abrasive waterjet cutting technology

The submitted paper aims to clarify the abrasive waterjet technology, particularly from the point of view of produced surface topography. It provides a new insight into the deformation process caused by the effect of abrasive waterjet and into the possibilities of using the surface topography for solving the issues of optimization of the process. The subject of study is a system of cutting tool, material and final surface topography and optimization of their parameters. The cutting or disintegrating tool of abrasive waterjet technology is flexible. The trajectory of its cut traces is strictly determined here by disintegration resistance at critical moments of tool-material interaction. The physico-mechanical character of the interaction within the cut will manifest itself in the final surface condition. This process can be re-analysed by measuring the selected elements of topography and roughness on the final surface, namely depending on the depth of the cut, technological parameters of the tool and mechanical parameters of the material. The mentioned principle is the basis of the presented solution. It lies in the analytical processing and description of correlation interrelations between set technological and measured topographical quantities in relation to the depth of cut and the type of material.Web of Science13528527