| Abstract [eng] |
The topic of the research carried out in this Master's thesis is "Investigation of frame vibrations in a straw chopper frame of a self-propelled combine harvester". The aim of the study is to investigate the oscillations of the tangential straw chopper frame of a combine harvester with variations in the condition of the chopping blades, in order to determine the effect of wear on the performance of the chopper. The problem for which this study has been carried out relates to the vibration-induced bearing collapse and chipper frame breakage that occurs in working agricultural practice. This failure results in significant financial losses, which can be avoided by the implementation of the diagnostic system proposed in this work. The smooth and uninterrupted operation of agricultural machinery during the season is a goal of every farmer and agricultural company, and research and development are constantly being carried out to ensure the smooth operation of the machinery on which mankind's food supply depends. The instruments used for the study are an accelerometer and an oscilloscope with software for measuring oscillations. The RMS of the signal was calculated to assess the variation in the condition of the chopping knives. The study was carried out in two phases: in the first phase, measurements were taken while the technical condition of the combine harvester was changing, and in the second phase, measurements were taken while this factor was being eliminated, and then the data obtained were compared. The results of the study showed that after 360 hours of operation, the uneven wear of the blades results in a mass imbalance that coincides with the rotational frequency of the shredder. In order to avoid this problem, the MSc thesis proposes the introduction of an oscillation monitoring system to monitor the changing technical condition and to signal to the harvester operator the planning of repairs. This proposed system is of the non-destructive diagnostic type and will therefore simplify the diagnosis of the technical condition of this combine harvester unit and the planning of the servicing This study provides additional knowledge on the performance of the crusher and practical recommendations for farmers and companies providing threshing or combine hire services, as this system will help to predict the time needed to repair the combine harvester, and is also useful for combine harvester manufacturers. |
