| Popis: |
Recently, electrical cordless chainsaws were introduced, which provide less harmful working conditions for the operators, and should therefore be deployed as much as possible in all non-professional and professional applications. The low power of the electric engines may result in lower efficiency and higher energy consumption in the case of over-tensioned chains, due to increased friction between the saw and the chain. Therefore, a partial factorial experiment with one factor on three levels (saw type) and two factors on two levels was designed, whereby a wooden beam was cross-cut at two levels of chain sharpness and tension. The time of cross-cutting and energy consumption were controlled. The chain tension does not have a significant effect onto time of cross cutting, or electricity consumption. Both have cross-cutting and energy consumption have been found to differ significantly when comparing the saws used in the experiment. The average efficiency of cross cutting using electrical chainsaws reported is 2.35 times lower than when using petrol powered saws. The lower efficiency is caused by the lower engine power of electrical saws, and lower speed of chain rotation. Energy consumption and time of cross cutting are significantly higher when using a blunt chain, with large differences in time of cross cutting and electricity consumption, making the chain sharpness the most important of all controlled factors. In the study, we did not find evidence that over tensioning of the chain increases the time of cross cutting or energy consumption, however the integration of such systems is recommended because of the worker’s safety. |
