Abstract. With the increasing demand for renewable energy in the domestic market, additional attention is paid to the use of stump-wood in energy supply. The stump harvesting technology is not substantiated sufficiently so that the end users can use this unpredictable raw material to generate heat and power. Service providing logging companies need to know the specific requirements to equipment and the characteristics of stump harvesting technologies in order to assess the possibility of acquiring this natural resource. The stump harvesting should be planned along with the regenerative felling, because the layout of the timber forwarding roads and the characteristic of the logging residues layer on the road surface are important. In its turn, when planning the upper timber yard, it is necessary to take into account the meteorological data, the prevailing wind direction and water streams. The aim of the study is to find out the total energy balance during the stump extraction with the MCR500 bucket. Working time, output volumes and productivity indicators are derived from the project "Development and testing of a prototype of multifunctional equipment for stump-wood production and preparation of the soil mounds" (2DP/2.1.1.1.0/10/APIA/VIAA/174) results and from the results of the joint stock company "Latvia state forest" project implemented in 2008. The most energy-consuming process is comminution of biomass, therefore it is common, for instance, in Finland that electricity-operated equipment located near the customer is used to carry out this work. More efficient use of forest resources by stump extraction and further utilization in heat and power production can increase biomass deliveries for energy applications by 500 thousand tons of dry matter of currently unused coniferous stump biomass annually.
The article reflects the relevance of the mechanization of work and individual operations in the course of planned thinning in forests of various types. The specific operating conditions of machines used for this type of forestry work are determined. The principles of construction of transmissions of machines for various purposes are considered, a method for determining external parameters and constructing a kinematic diagram of an inter-axle controlled power distribution mechanism in its composition is proposed. The results of kinematic and force analysis for the considered example of the mechanism are presented. Prospects for using the mechanisms of this family are formulated.
In recent years, the enterprises of forestry and the Ministry of Energy of the Republic of Belarus and other countries widely implemented advanced milling tools designed to chop wood, stumps and roots without immersing the cutter in the soil (mulchers) and with immersion (rotovators), which allows you to prepare the ground for planting forest crops. They can be mounted on multi-purpose tractors, loaders and excavators. At the same time, there are no methods that allow carrying out a reasonable choice of technological equipment for a particular basic machine, since a significant number of production, technological and technical factors have an impact on the emerging power and capacity parameters. The proposed method allows taking into account a significant number of variable values (working methods, speeds of various operations, parameters of the working body, its drive and base chassis, soil conditions, etc.) and simulate the interaction of milling tools under various operating conditions. It was found that the greatest loads on the mulcher rotor occur during the felling of tree and shrub vegetation, which is associated with an increase in the area of interaction between the cutters and the wood up to 2 times compared with the chopping of similar lying stands. This value can be reduced by 15–30 % depending on the diameter of the trunks being processed. In the case of a significant amount (cluster) of forest stands with a diameter of more than 10 cm, it is preferable to carry out work at a speed of about 0.2 m/s or advanced felling of these trees. The use of hydraulic travel (speed) reducers or hydrostatic transmission is promising in order to reduce dynamic loads and get better adaptability of the working equipment to natural-production conditions (the ability to work at a speed from 0 to 5 km/h). It should be noted that the installed required engine power for the milling equipment drive should be increased by 10–15 % due to the needs of the drive of various equipment located on the base chassis. Also, in the case of the integrated use of tree and shrub vegetation, it is possible to use mulchers that collect biomass; however, this will require additional energy costs. In this regard, the method can be applied when choosing the parameters of technological equipment for the existing base chassis, to solve the inverse problem, and also to select the operating mode of the milling equipment depending on the natural and production conditions with the possibility of subsequent prediction of the effectiveness of the work performed.
The article presents the results of theoretical and experimental studies of weight and linear wear from resource indicators of cultivator paws hardened by the combined method. It is established that in order to achieve an increased resource of cultivator legs, world manufacturers use special alloying materials, design features and technological methods of hardening, namely heat treatment, application of wear-resistant materials. The most commonly used methods for strengthening the working surfaces of parts are conventional hardening of medium-carbon, high-carbon and alloy steels. The hardness of the metal can be obtained in the range of 45 HRC for steel 45 and up to 65 HRC for steel 65G and alloy steels. To determine the change in the geometric parameters of the blades of cultivator legs during production tests recorded linear wear, weight wear and the radius of rounding of the cutting edge of the working bodies with an operating time of 8, 23, 42 and 54 ha. According to the results of linear wear of the wings of experimental cultivator paws during production tests, the materials that provide the best performance against abrasive wear were determined. As a result of the analysis of cultivator paws with a yield of 54 ha, it was found that the working bodies do not have visible damage and extreme wear and are suitable for further use. At the same time, measurements showed that the amount of wear on the width of the blade is 5.3–11.9 mm.
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