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An analytical method is presented for force analysis of plain lever mechanisms with one degree of freedom, based on the vector method. Using the example of a two-drive structural group, a method is outlined for finding reaction vectors in all its kinematic pairs, while maintaining the clarity and consistency of the solution inherent in the graphic-analytical method of diagrams of component forces. An original analytical description is given for finding the vectors of tangential and normal components of reactions in kinematic pairs. Application of the proposed method of force analysis makes it possisble to find reaction vectors in kinematic pairs without compiling and solving complex systems of equilibrium equations or graphical construction. Adaptation of the proposed force analysis in modern mathematical packages allows for the study of plain lever mechanisms with one degree of freedom in a short time and with high accuracy.

The purpose of the research is to substantiate the critical rotation speed of a rotor with bent blades based on force analysis and modeling the movement of mixture particles in a horizontal loader of a circulation mixer. The research method[1]ology included the substantiation of the highest rotation frequency of the loader blade rotor based on a force analysis of moving particles of forces when they were moved by the bent blades of the loader and compliance with the conditions for the entry of flying particles into the tray. The numerical analysis performed on the basis of the obtained expressions using the Mathcad mathematical package made it possible to establish the critical values of the rotation speed of the rotor-loader with bent blades based on the condition of the material coming off the blade and the condition of the flight of particles from the blade into the receiving tray. With radial blades, the limitation is the entry of particles into the receiving tray at a critical frequency of 43 min-1 , then for a blade bend of 30° – about 60 min-1 , for a blade bend of 45° – about 70 min-1, for a blade bend of 60° – about 80 min-1. The lowest critical values of the rotor-loader rotation frequency from the condition of particle movement along the blade correspond to the blade bend angle of 27–60° and are determined by the friction coefficient of the material, amounting to 83–78 min-1. With an increase in material friction, the critical values of the rotor rotation speed from the condition of material coming off the blade decrease slightly, and the bend angle for the rotation speed extremum increases. The highest rotation speed of the rotor - loader with a radius of 0.12 m is limited to 78 min-1 at a blade bending angle of the order of 30–60°, determined by the friction of the material on the blade.

The productivity of the wood grinding process can be increased by using abrasive wheels with spherical corundum grains. They also expand the area of application of rigid abrasive instruments by reducing soiling and eliminating burns on the treated surface. The studies revealed several advantages of the abrasive wheels over sanding paper: very precise processing, achievement of the desired grade of the treated surface, high durability of the instrument, and low cost. A force analysis of a grinding surface with micro-cuttings made of spherical corundum grains was performed depending on the degree of its wear. The results revealed that chip removal by the spherical corundum grains was possible only under certain conditions when the cutting edges of the grains were exposed. Besides, the theoretical dependencies of forces in micro-cutting were obtained from every principal condition for the process of grinding wood and wooden materials: properties of the spheres, treatment modes, and material-related factors. The special properties were analyzed by the chip formation process and self-sharpening conditions of the spherical corundum wheels. The grain size had the greatest influence on the thickness of chips which were cut by one grain. The grain content and bonding, like other properties of the internal volumetric structure, had a less substantial impact. The abrasive tool characteristics must complement the processed material, such as grain size, hardness, and structure. On the other hand, spherical corundum has optimal physical and mechanical properties for grinding, particularly the thickness of the grain’s edges, which primarily determine the material’s tensile strength. The grinding depth and feed rate mostly define the parameters of the grinding performance of wood and wood-based materials. An increase in those leads to a rise in cutting forces, roughness of the ground surface, a reduction in the grinding length over the period of the wheel’s durability, and the grinding coefficient. If the grinding depth and feed rate are constant, the performance can be improved by increasing the cutting rate. For citation: Sergeevichev A.V., Sokolova V.A., Mikhailova A.E., Ovcharova E.O., Voinash S.A. Force Analysis of a Single Grain Cutting Process in Wood Grinding Using Spherical Corundum. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 3, pp. 140–154. (In Russ.). https://doi.org/10.37482/0536-1036-2023-3-140-154

The article presents a method for calculating and designing spherical roller gears with a double-row pinion. The studied gears are analogs of planetary gears with a double-wheel pinion. They make it possible to implement a wide range of gear ratios. The advantages of spherical roller gears include small dimensions, low material consumption, and layout properties. A special feature of the proposed calculation algorithm is the search for optimal geometric gears parameters according to the criteria of maximum efficiency coefficient taking into account maximum load capacity for a given maximum radial dimensions. The main criterion of strength is fatigue endurance. The method includes design and verification calculations. It makes it possible to develop the small-sized speed reducers for low-speed drives for various purposes.

Mobile rope systems designed to carry out loading and unloading and transport and transfer operations in noequipped or hard-to-reach areas and ensuring the prompt deployment of the necessary technological means are a promising type of lifting and transport equipment. The article deals with the layout of the main technological equipment of one of the constructive variants of a mobile rope system on a base multi-axle wheeled chassis of high carrying capacity and performance. A variant of the layout with the central location of the end tower attachment point for supporting the leading rope pulley with a carrying rope on the base chassis frame is considered. Mathematical models have been developed that ensure the kinematic and power analysis of the kinematic scheme of the hydraulic mechanism for installing and fixing the end tower. The analysis of the influence of the main structural dimensions of the indicated mechanism on the dimensions of the mobile rope complex in the transport position, as well as on the force factors arising during the operation of the rope system is carried out. The necessary conditions have been established that must be met when designing a rope system to ensure the regulatory requirements for the movement of a mobile complex on automobile roads of the general using. The conditions for the location and length of the drive hydraulic cylinder of the end tower, which ensure the necessary movement of the tower from the transport position to the working position, have been established and analyzed; the presence of a significant zone of inadmissible location of the hinged assembly for attaching the hydraulic cylinder rod to the metal structure of the end tower has been revealed.