Автор: Krasimira Atanasova
Статии
- INFLUENCE OF SOME FACTORS ON ADHESION STRENGTH IN THE FORMATION OF WATER-BASED FINISHES ON BEECH PLYWOOD
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Резюме
Adhesion strength is an indicator of the coating’s detachment resistance from the base. The magnitude of the adhesion strength depends on the nature of the lacquer system, the type and state of the substrate, and the film formation conditions. In this study, a water-based varnish system was applied to beech plywood. The influence of а sandpaper grit size used and the time between а sanding and coating processes has been determined.
Ключови думи: adhesion strength, plywood, sanding, water-based finishes, coating
- INFLUENCE OF THE MOISTURE CONTENT OF FROZEN LOGS ON ENERGY REQUIRED FOR THEIR DEFROSTING IN BOILING PITS
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Резюме
With the help of our own non-stationary model, the temperature field and defrosting durations of frozen beech logs with a diameter of 0.4 m, initial temperature of −10 oC, and moisture content of 0.4 kg∙kg-1, 0.6 kg∙kg-1, and 0.8 kg∙kg-1 were determined at water temperatures in the boiling pit equal to 80 oC. Using the determined durations, the change in energy required for carrying out of the entire defrosting process and that for each of the 5 components of the pit's thermal balance was calculated. Computer simulations were performed for a well-insulated concrete pit with working volume of 20 m3 and degree of filling with logs f equal to 25%, 50%, and 75%. It was found that at maximum possible value f = 75% the total energy consumption of the pit increases from 145.1 kWh.m-3 to 180.2 kWh∙m-3, i.e. by 24.2% when the moisture content of the frozen logs increases from 0.4 kg∙kg-1 to 0.8 kg∙kg-1. With a decrease in f, the thermal efficiency of the pit decreases almost proportional to f, mainly due to the increase in the specific energy required to heat the water in the pit.
Ключови думи: concrete pits, heat balance, defrosting of logs, wood moisture content, energy consumption
- PRODUCTION OF FURNITURE ELEMENTS WITH PARTICLEBOARD CUTTING WASTE CORE
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Резюме
The scarcity of natural resources and the generation of waste without adequate disposal are worldwide concerns related to the linear production model. The present study is part of a research project to create a technology for the utilization of laminated particleboard cutting waste in furniture element production. A layer of waste details was laminated on both sides with High Pressure Laminate (HPL) with a thickness of 0.8 mm. Polyvinyl acetate adhesive was used for lamination. The influence of the lamination process conditions and the arrangement scheme of the core details on the appearance, bending strength, and processing features in the subsequent technological phases of the manufacturing process has been established.
Ключови думи: waste utilization, laminated particleboard, lamination, HPL
- EFFECT OF STAINING ON THE ROUGHNESS OF BEECH FURNITURE SURFACES
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Резюме
Staining is a process of transparent wood surface colouring. Stains are liquid systems that wet and penetrate treated surfaces, changing their properties, including their roughness. The article presents research on the surface roughness change of beech, beech plywood, and beech veneered wood-fibre boards after treatment with waterborne and solvent-based stains and waterborne stains with PVA resin additive. Before staining, the surfaces were sanded with P150-grain sandpaper. A contact roughness tester model SJ-210 and a standard Gaussian filter were used to evaluate the roughness. The influence of the substrate structure, the stain dilution and the type of thinner on the surface roughness were determined. The parameters Ra, Rpk, Rk, Rvk and the composite parameter Rpk+Rk+Rvk were analysed. The results are presented graphically and also in tables.
Ключови думи: waterborne stain, solvent-based stain, roughness, beech, beech plywood