Abstract:The paper deals with the problems of introducing biodegradable oils in relation to the environmental protection. In the course of the research, the parameters were tested and improved of a number of rapeseed-based oils. Thus, two groups of oils were created to enable to distinguish raffinates and recycled oils. Recycling can remove the greatest disadvantage of raffinates, namely their thermo-oxidation instability, which becomes evident particularity by the formation of hardenable polymer deposits. The deposits result in the loss of the function of the components of the hydraulic circuit and gearbox. The methods of testing are based on the follow-up of the changes in acid value, kinematic viscosity at 40°C, water content, and peroxide number during the service life test. It has been proved that peroxide number characterises very well the thermo-oxidation stability, which is nearly unsatisfactory in raffinates. Within the cooperation in the international program KONTAKT, compliance tests were carried out of recycled rapeseed-based oil NAPRO 2003 in a hydraulic circuit and gearboxes. Their results are compared with the parameters of the best-recycled oils available.
Decomposition of cutting forces in quasi-orthogonal CNC milling. The paper is focused on the analysis of cutting forces in milling of MDF boards on the CNC machine called SCM Tech 99 L. The Kistler 9257 B is top-of-the-line dynamometer with DynoWare software used to measure power and analyse data. The forces were examined and analysed using quasi-orthogonal milling with a single-edged blade. The resulting force values were compared with each other depending on the conventional and climb milling of the edge of the MDF board at various feed speeds.
The paper deals with the dependence of using basic types of machining technologies on the surface quality of most common wood. In wood-processing industry, cutting by circular-saw blades and milling are the most often used technology to machining wood materials. The quality and accuracy of the machining are derived from the machine construction, shape and the amount of saw teeth, kind of wood species, feed per tooth and the size of the tool. Research was carried out on an experimental milling stand at setting various feed speeds and the spindle rpm, on an experimental cutting stand at using three types of circular-saw blades in the field of optimum and resonance rpm. Evaluation of the surface quality was carried out on a top multisensor apparatus Taylor Hobson-Talysurf CLI 1000 using a contactless method by a confocal sensor. Software equipment of a powerful computer was provided by the Talymap platinum program. Tree species were evaluated generally from the aspect of roughness and waviness altogether. An expert evaluation is carried out from two aspects. The first aspect is selection of the best technology for actual wood and the second aspect is selection of the best species for the actual technology. Particular relationships between wood and technology are evidently best described by graphs.
ABSTRACT:The paper is a response to the problem of the environment pollution by oil product spills from mechanisms of forest and agricultural machines. The problem can be dealt with through the replacement of mineral oils by biodegradable oils. Information concerning the measurement of parameters of these oils was published by the author. It has been demonstrated that the parameters are broadly suitable with the exception of thermooxidation stability. The paper is, therefore, aimed at improving the thermooxidation stability of biodegradable oils of HETG type. Oil raffinates based on rape oil, methyl esters are delivered in various quality, mostly with a service life of 600 to 2,000 service hours at a temperature of max. 70 o C. Methods of testing are based on monitoring the change in acid value, viscosity, water content and peroxide number during the service life test. It has been proved that peroxide number characterizes very well thermooxidation stability which is nearly unsatisfactory in raffinates. A method for improving the thermooxidation stability has been proposed using high superheating of oils at the beginning of use and their subsequent treatment. Thus, deep-frying oils (HETG) characterized by a short-term thermal stress appear to be suitable. Through filtration and other treatment three types of samples were developed and tested. The advantage of the procedure consists in the fact that esterification does not occur. Results of the tests are evaluated and compared with properties of traditional raffinates. It is possible to conclude that thermooxidizing stability of the oils has been substantially improved, other parameters in additivated samples are comparable with raffinates.
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