Projektiranje i konstrukcija uređaja za cijepanje drva

Heating by solid fuels, and especially fire wood, belongs to the most asked and requested types of heating in cottages. One of the main problems of heating is wood splitting as a fi rst operation. A very useful tool for splitting of wood material is a log splitter. This contribution is focused on how to apply a screw type log splitter in wood splitting. A set of experiments have been realized to get an appropriate shape of the splitting cone, which will provide an improved splitting action. The cone has been manufactured on the basis of the experimental results. The experimental apparatus has been developed to determine the validity of the splitting cone and its geometry design.Grijanje na kruta goriva, posebno na drva za ogrjev, pripada među najčešće vrste grijanja u vikend kućama. Jedan od glavnih problema tog načina grijanja jest potreba cijepanja drva prije loženja. Vrlo koristan alat za cijepanje drvnog materijala jest cjepač drva. Ovaj je rad usmjeren na specifi čnu upotrebu vijčanog tipa cjepača drva koji znatno olakšava cijepanje drva. Klin za cijepanje drva proizveden je na bazi eksperimentalnih rezultata istraživanja. Razvijena je eksperimentalna oprema za cijepanje drva kako bi se ispitala valjanost klina za cijepanje i njegova geometrija

An approximation of deflection line function at the rod loaded by buckling under self-weight

Rad se bavi aproksimacijom točne funkcije linije otklona za štap opterećen izvijanjem zbog vlastite težine pomoću funkcije, što je najbolje prikazano točnim oblikom ovog štapa. U ovom radu predlažemo metode derivacije kritične duljine izvijanja pomoću točnog rješenja i pomoću metode energije. Za zamjenske funkcije linije otklona su izabrane varijante goniometrijskih funkcija i polinomi. Pojedinačni koeficijenti funkcija su izabrani na temelju postojećih rubnih uvjeta i u slučaju nedovoljnog broja, oni su izabrani kako bi se izrazio točan oblik linije otklona štapa na najprikladniji način, koji je prenesen iz konkretnog primjera rješenja pomoću softvera SolidWorks. Rad prikazuje pogreške kritičnog izračuna duljine izvijanja nasuprot točnom rješenju, kao i maksimalna apsolutna i relativna odstupanja kod bočnog pomicanja za odabranu funkciju. Od pojedinačnih zamjenskih funkcija je naknadno izabrana ona koja ispunjava uvjet za opće korištenje i ima najmanja odstupanja od točnog rješenja.The paper deals with an approximation of the exact deflection line function at a rod loaded by self-weight buckling via the function, which is best-presented by the exact shape of this rod. In this paper, we suggest the methods of derivation of the critical buckling length by the exact solution and by the energy method. For the substitute functions of deflection line, the variants of goniometric functions and polynomials are chosen. Individual coefficients of the functions are chosen on the basis of existing boundary conditions and in the case of their insufficient count, they are chosen in order to express the exact rod deflection line shape in the most suitable way, which was transposed from the concrete example solution by SolidWorks Simulation software. The paper shows the errors of critical buckling length calculation against the exact solution, as well as the maximum absolute and relative deviations in the lateral displacement for the chosen function. From the individual substitute functions, one function that meets the condition for general use and has the lowest deviations from the exact solution, is subsequently chosen

Monitoring of vulcanization process using measurement of electrical properties during linear increasing temperature

The article presents the possibilities of diagnostics of irreversible chemical reaction vulcanization in case of laboratory prepared rubber mixture based on styrene - butadiene (SBR) using measurements of selected physical parameters. Our work is focused on the measurement of current rheologic parameters (torque at defined shear deformation) and selected electrical parameters (DC conductivity) during linear increasing temperature. The individual steps of vulcanization are well identified by means of measurements of rheologic parameters, while significantly affecting the value of the electrical conductivity. The value of the electrical conductivity increases with the increasing of rate of the crossbridging reactions during vulcanization. The rate of the heating affects both types of measurements. When the rate of the heating is increasing the temperature of the beginning of networking step of reactions and also the rate of vulcanization grow. The sensitivity of the both types of measurements allows a good mathematical description of the temperature dependence of the torque and the electric conductivity during the vulcanization of rubber mixtures based on SBR

The Systems Design of Transport Line in Water Sand Pit

Import 29/09/2010Hlavnou témou mojej diplomovej práce je návrh systému dopravnej trasy vo vodnej pieskovni, pre maximálny hodinový ťažobný výkon od korčekového bagra Q = 170 t.hod-1. Diplomová práca je členená na štyri časti. V úvode som podrobne priblížil problematiku ťažby piesku z priestoru pod hladinou spodnej vody. V ďalšej časti som konštrukčne navrhol plávajúci pásový dopravník pre dané parametre. Následne som konštrukčne navrhol plávajúce teleso s plavákmi valcového tvaru a pre toto teleso som skontroloval plávateľnosť a stabilitu, vrátene základných technologických výpočtov. Poslednou časťou je podrobný technický výkres plavákového telesa, ktorý tvorí prílohu mojej diplomovej práce.The main theme of my thesis is the design of a water transport line in water sand pit to achieve the maximum hourly mining capacity of Q = 170 t.hod-1 chain-bucket dredger. The thesis is divided into four parts. In the beginning, I described the problematic of extracting sand from the area below the level of groundwater in detail. In the next part, I designed a floating belt conveyor for given parameters. I subsequently designed floating body with cylindrical shaped floats and I also controlled the buoyancy and stability of this body with the basic technology calculations included. The last part – the attachment of the thesis - consists of a detailed technical drawing of the float body.342 - Institut dopravyvýborn

Slewing mechanism of the mobile crane

Import 25/06/2008Prezenční342 - Institut dopravyNeuveden

Use of Methane-Free Synthesis Gases as Fuel in an Spark Ignition Combustion Engine

The presented article deals with the use of methane-free synthesis gases in a spark-ignition internal combustion engine. The authors analyse the influence of seven synthesis gases on integral as well as internal parameters of the engine and make comparisons with operation on methane. The main combustible components of the synthesis gas are hydrogen and carbon monoxide and the remainder are inert gases (nitrogen and carbon dioxide). At the operating speed of the combustion engine of 1500 rpm, at which the cogeneration unit operates, in comparison with methane a decrease in power parameters was recorded in the range from 19 to 35%. The increase in the hourly fuel consumption was 6 to 8 times higher. Depending on the gas composition, the optimum start of ignition angle at full load ranged from 17 to 26 °CA BTDC. In terms of analysis of internal parameters, the cyclic variability of the pressure in the engine cylinder, which characterizes the stability of its operation, was in synthesis gases operation mostly at a lower level (from 3.6% to 6.9%) than in methane operation (6.8%). Due to the presence of hydrogen, the main combustion time interval of all synthesis gases has been shorter compared to methane. The presented results serve to better understand the setting of the waste gasification process so that the highest possible energy and economic recovery in the cogeneration unit is obtained

Influence of Selected Synthesis Gas Component on Internal Parameters of Combustion Engine

The paper deals with the influence of selected component of synthesis gas on internal parameters of combustion engine that is planned to be used in micro-cogeneration unit. The aim is to better understand the mechanism of combustion of carbon monoxide mixed with methane and as a follow-up to optimize the operation of the Lombardini LGW 702 engine on change of fuel composition. Generally, an increasing proportion of carbon monoxide in methane mixture leads to a decrease in engine performance (mean indicated pressure) and the hourly fuel consumption in each of the operating modes of the engine increases. With growing proportion of CO in mixture with CH4, the maximum pressure in the cylinder increases together with pressure rise rate up to approximately 10 % vol. of CH4. With further increasing proportion of CH4, there is a significant decrease of the before-mentioned engine parameters. The optimum ignition angle for pure methane, or carbon monoxide, does not change significantly and it is about 27° CA BTDC