Beater-knife cutting devices of forage harvesting machines and ways for their improvement

One of the main technological operations in the harvesting of stem fodder is harvesting with simultaneous chopping. Modern round balers, bale balers, and pickup trolleys are equipped with a beater-knife cutting apparatus. They are based on a rotating beater (a pipe with fingers fixed to it) and a number of knives installed in the channel, along which the fingers of the beater move in a rotational motion. In the process of developing the design of such a cutting apparatus, the beater has evolved from an analogue of a scraper-finger conveyor, a rotor with a controlled rake, into a rotor with a tubular shaft and fixed curved fingers radial to its base. The problem with such cutting machines is a significant increase in friction forces on the side surfaces of the knives with an increase in their number. The increase in the number of knives is caused by the need to reduce the length of the raw material to be cut. The research is aimed at determining the design features of the beater-knife cutting units of forage harvesters, the directions of their improvement by replacing the passive knife with an active disc knife and experimentally determining the effect of the circular speed of the knives on fuel consumption. The monographic method was used in the research. This made it possible to systematize the main design parameters of the beater-knife cutting machine, identify the main works carried out in the study of similar designs, and propose a technical solution that can significantly reduce the friction forces that occur on the side surface of the knives. By varying the distance between the knives of the prototype cutting machine, the weighted average cutting length of the resulting raw material was determined. The results obtained made it possible to determine the ratio between the dimensions of the cutting device (which are in the range of: length — 1120–2000 mm, diameter — 415–880 mm, minimum cutting length — 22–25 mm), experimentally confirm the performance of the cutting device with disc knives, establish the dependence of fuel consumption for picking up, cutting and feeding alfalfa on the circular speed of disc knives, and determine the minimum fuel consumption, which is 0.74 kg·hE−1.