On shredding of wood raw materials with knives of different designs

The market for renewable energy from forest residues has developed since the signing of the Kyoto Protocol to combat global climate change and due to the significant increase in hydrocarbon prices, which has also affected Russia. Many countries, such as Finland and Sweden, have developed technologies to utilise bio-resources, in particular wood, as fuel. This circumstance, as well as the tendency of domestic fuel prices to equalise with the cost of energy carriers on the world market, has contributed to an increased interest in the use of various fuels made from waste wood. In order to use this type of fuel, the raw material is chopped into chips of a certain size. The wood raw material is crushed by crushing machines, which differ in their mobility, type of cutting equipment and the type of chips produced. More than 70 % of the waste wood raw material is found in clearcuts. For this reason, mobile chipper technology is the most widely used in the forestry sector to produce the final product in the form of wood chips.Significant design range of this equipment and high efficiency proves the priority of its use in the production of fuel chips. The existing methods of designing wood chipping equipment cannot fully satisfy modern requirements for the development of new types of wood chopping machines. In the practice of wood raw material chopping the most widespread use has received straight knives, but they are characterised by high energy consumption of the cutting process, and the resulting chips do not meet the requirements for use in modern boiler units. Therefore, the proposed design of stepped knives will allow levelling the disadvantages of wood chopping by straight knives. The computer modelling of the working process of wood chips production from wood waste used in the research allows to carry out with a high degree of accuracy a comparative automated analysis of the efficiency of wood waste chopping by straight and stepped knives.