Автор: Pavlin Vitchev
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- EQUIVALENT SOUND PRESSURE LEVELS IN WOODWORKING MILLING MACHINES
Equivalent continuous sound pressure level LAeq is the main variable characterizing the physiological effects of noise on humans. The technological equipment for woodworking and furniture industry includes the woodworking milling machines, which at the same time are characterized with high levels of noise emissions.
The current study investigates the changes in equivalent sound pressure level measured at workplace during milling of details from common beech wood (Fagus Sylvatika L). The influence of the construction and rotational speed of the cutting tool have been studied.
It was found that depending on the cutting speed and the construction characteristics of the cutting tool, the equivalent sound pressure level LAeq for eight hour working day varies from 74 dB(A) tо 89 dB(A).
Ключови думи: noise, sound emission, equivalent level, noise during milling
- STUDY ON THE POWER – ENERGETIC INDICATORS OF A UNIVERSAL MILLING MACHINE
Experimental studies during milling of solid wood were carried out. The current study was performed at the Laboratory of Woodworking Machinery, University of Forestry, Sofia. The measurements were carried out using universal milling machine FD – 3 (ZDM – Plovdiv). The correlations between fundamental factors influencing the milling process and target functions, such as cutting force and power, specific cutting work, specific power consumption have been investigated. On the basis of the analysis of the obtained results, practical recommendations have been proposed.
Ключови думи: universal milling machine, cutting power, cutting force, specific cutting work, wood milling
- STUDY ON THE SOUND ABSORPTION CHARACTERISTICS OF WOOD FROM SCOTS PINE
In this paper, the absorption properties of wood materials from Scots pine (Pinus Silvestrys L.), which are widely used in flooring and wall linings, have been experimentally studied. The frequency-dependent sound absorption coefficient (αp) was determined in octagonal frequency bands with an average geometric frequency of 100 Hz to 2000 Hz. The tests were carried out using an impedance tube, according to the requirements of BDS EN ISO 10534-1:2006. The obtained results are of a particular interest from both scientific and practical point of view, given that the sound absorption coefficient has a decisive impact on the reverberation time. The latter is the main acoustic parameter of a room depending on its intended purpose.
Ключови думи: sound absorption, Pinus silvestrys, reverberation time
- INFLUENCE OF THE CUTTING MODE ON THE SURFACE QUALITY DURING LONGITUDINAL PLANE MILLING OF ARTICLES FROM SCOTS PINE S
The current study investigates the changes in the surface quality of experimental samples of Scots pine (Pinus sylvestris L.) wood during a milling process, performed with different rotation speed of the cutting tool (n), feed rates (U) and different thicknesses of the removed layer (h). On the basis of the performed experiments, graphical dependencies, representing the relationship between the different factors have been derived. In order to achieve a higher quality of the milled (processed) surfaces, practical recommendations for the optimal values of the evaluated factors have been suggested. The surface roughness of the material (surface) was measured with a roughness tester, type „SurftestSJ-210“ (Mitutoyo, Japan).
Ключови думи: milling, surface quality, cutting mode, Scots pine (Pinus sylvestris)