No abstract

No abstract

Technological and structural parameters of a threshing unit must ensure the highest possible quality of its operation under minimum input and cost. The aim of the study was to estimate the variation of speed of threshing cylinder with two different shapes of filler plates (FP-I and FP-II) under various corn ear feed rate into combine harvester. Threshing cylinder speed (frequency of rotation) nb (min-1) was measured simultaneously each 0.075 s using stationary tangential single-cylinder threshing unit located in laboratory-training ground intended for investigation into technological processes of agricultural machinery. Frequency of rotation of non-loaded threshing cylinder speed amounted for 450 min-1. Increase in corn ear feed rate from 6 kg s-1 to 12 kg s-1 caused frequency of rotation of threshing cylinder to decrease from nb=437.82±0.21 min-1 to nb=420.96±0.50 min-1 (using FP-I). Replacing covered spaces between rasp bars with FP-II had no effect on cylinder speed – it has decreased from 438.06±0.23 min-1 to 421.37±0.32 min-1. Results showed that in case of FP-I, the amplitude of speed Anb has increased from Anb=4.07±0.44 min-1 to Anb=8.60±0.88 min-1, whereas in case of FP-II – from Anb=2.67±0.25 min-1 to Anb=4.52±0.62 min-1 in response to increased feed rate from 4 kg s-1 to 12 kg s-1. This means that using the covers FP-II the threshing apparatus will work more evenly. The average threshing cylinder speed, irrespective of the closure of spaces between rasp bars, was found to decrease by approx. 20 min-1 in result of increase in corn ear feed rate from 4 kg s-1 to 12 kg s-1. When threshing corn ears, irrespective of the shape of filler plates, the acceptable feed rate amounted for 10 kg s-1, as it caused to exceed the permissible limit of 5 % allowed for decrease in cylinder speed (nb=427.5 min-1).

When applying soil, environment and energy sustaining tillage and drilling technologies, cultivation and seed incorporation become more complex. Crop residues left on the soil surface have a considerable influence on the process of tillage and drilling machinery operation. They aggravate the operation of tillage and especially that of drill coulters. Most often soil, environment and energy sustaining tillage and drilling technologies use disc coulters which can cut, break or press crop residues into the notch made by the coulter in the soil while interacting with the soil surface. The objective of this work is to investigate the forces of breaking or cutting fresh or overwintered straw of winter wheat and spring barley influencing the process of tillage and drilling machinery operation. Research on cutting and breaking crop residues was carried out during the period of 2011-2012 in the Tribology Laboratory of Aleksandras Stulginskis University. The fresh straw of winter wheat and spring barley of 22% moisture content and overwintered straw of 5% moisture content with nodes and without nodes were used for the research. Our research evidenced that the crop residues of spring barley were easier to break compared with those of winter wheat. About 160 N force is needed to break fresh straw of winter wheat with nodes or without them compared with the analogous type of spring barley straw -about 53 N force. Great influence on breaking characteristics is made by leaving the crop residues to overwinter on the soil surface. However, the research showed that the characteristics of the winter wheat and spring barley crop residues left to overwinter vary unevenly. The force for breaking the overwintered winter wheat straw decreases by about 3.2 times compared with the fresh straw of winter wheat and the force for breaking the straw of overwintered spring barley decreases by 34%. The research on cutting crop residues with a knife simulating a disc coulter showed that the cutting of the fresh and overwintered crop residues of winter wheat and spring barley at the node and other section of the straw differs signally. In order to cut the fresh straw of winter wheat and spring barley at the node 35 to 43 N weaker force is required compared to cutting at other sections of the straw. To cut the overwintered straw of spring barley and winter wheat at the node 18% to 30% weaker force is required compared with the fresh straw. During the cutting at the node the straw of winter wheat and spring barley is deformed less and more slowly compared to solid straw without nodes.

Corn ear feed rate variations in the threshing-separation unit of a combine harvester have a significant impact on the dynamic indicators of the threshing process. In this study, we conducted experiments using a stationary tangential threshing device and measured the forces acting on the rear part of the concave as well as the torque of the rotating cylinder during a threshing process. The ThreshLab software was developed for this purpose. We found that increasing the corn ear feed rate made the threshing process more even, due to decreasing the fluctuation of forces acting on the rear part of the concave and torque of the rotating cylinder. The corn ear threshing process may be more stable if the threshing cylinder is fitted with filler plates (FP-II). A comparison of the results obtained for variations in the forces acting on the rear part of the concave with those obtained for variations in the total torque of resistance and the speed of the threshing cylinder revealed a linear correlation between these parameters at varied feed rates. DOI: http://dx.doi.org/10.5755/j01.mech.24.4.20721