Development of a Method for Obtaining a Wear-Resistant Coating for a Cutting Tool

The article presents a method for producing a nanostructured wear-resistant high-hard coating with high physicomechanical and strength characteristics, resistance to shock and vibration loads. The result is an increase in adhesion between the substrate and the coating, as well as an increase in microhardness. One of the common methods of metal cutting is band-cutting machines that use closed band saws as cutting tools. Since materials with high physicomechanical characteristics (hardness, strength, etc.) are increasingly being used in modern production, which significantly complicates the cutting process and makes increased demands on the cutting tool. To expand the range of processed materials for which the productive use of band-cutting machines is possible, it became necessary to create a band saw with higher cutting characteristics. At the same time, the specificity of the working conditions of the band saw shows that the blade should have such characteristics as increased vibration resistance, resistance to alternating and dynamic loads, and the cutting part of the saw should have increased resistance to shock, dynamic, alternating loads, have high hardness, as well as increased wear resistance.

Full dynamic reactions in the main links of big band saw machines

In this study, the full dynamic reactions in the bearing supports of the leading wheel of big band saw machines are determined. These reactions are caused by both the external loads and the kinematic and mass characteristics of the rotating disk. Expressions for calculating the dynamic reactions caused by external forces and moments that occur in the operating mode are obtained. The influence of the kinematic and mass characteristics of the rotating disk is studied and expressions for calculating the dynamic reactions caused by these characteristics are obtained. Expressions for calculating the full dynamic reactions that load the bearing supports of the leading wheel are obtained. With the help of these expressions, the parameters of the band saw machine can be selected in such a way as to ensure a minimum load on the shaft and bearings.

Plate Dampers in the Tensioning Plate Dampers in the Tensioning

The article analyses strengths and weaknesses of bandsaw machines. While analysing we have found the relationship between the weaknesses and the tension of a band saw. Its use as a cutting tool leads to a decrease in the lateral rigidity and stability of the cutting section on the pulling chain. This leads to fluctuations in the cutting width, a decrease in the geometric accuracy of sawn timber and an increase in the roughness of the side surfaces of a kirf. The main types of tensioning unit mechanisms, which strengthen the tension and maintain its stability during operation, are defined, and common design flaws are described. Oil-filled metal plate dampers promote space-saving and low-inertia dampers for bandsaw machines with any basic saw blade tensioning mechanisms. The influence of the device on the level of dynamic fluctuations of the tensile force caused by the artificial eccentricity of the tension pulley was studied. The efficiency was evaluated by computer oscillography of the tensile load sensor signal and subsequent computer processing of the obtained oscillograms. The effectiveness of using damper devices is confirmed by the quality of sawing, which is characterized by a lower level of roughness of the lateral surfaces of the cut while reducing the variation in thickness of a workpiece. Methods of eliminating flaws with different types of tensioning units are reviewed, and the effectiveness of using oil-filled plate dampers is evaluated. The article presents the research technique and parameters of the experimental unit as well as the conclusions on the effectiveness of damping devices. For citation: Alekseev A.E., Dumanskij I.O., Prokhorov A.V. Plate Dampers in the Tensioning Units of Bandsaw Machines. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 142–149. DOI: 10.37482/0536-1036-2021-5-142-149

Improving the quality of the band saw cut

This article is devoted to the study of the dynamic characteristics of the band sawing process to improve their efficiency. The object of study is: band saw, softwood. A screening experiment was carried out when sawing with band saws to identify key influencing factors on the quality of the treated surface (roughness) and sawing force (sawing power). Rational values of key influencing factors were determined. The effectiveness of the sawing regimes with band saws was evaluated. In the course of laboratory tests of the new saw, it was found that the moisture content of the wood has the maximum effect on the quality of the sawing walls. According to the degree of influence of factors, the roughness of the cut depends on the moisture content of the wood, the feed per tooth, the type of cutting relative to the wood grain and the height of the cut. As a result of a multivariate experiment, two regression equations were obtained for the assumed roughness of the cut and the cutting power. The estimation of the significance of the coefficients in the given interval of variation of the influencing factors is carried out.

Research of dynamic processes at cutting forest materials on horizontal band saw equipment

For processing small-scale wood, as well as wood from logging and sanitary logging, small enterprises are created that use fairly large and expensive band saws of various foreign firms and domestic production, which have a high energy intensity of the technological process. In this regard, the development of a resource-saving band saw machine that improves the quality of saw products and reduces the energy intensity of the technological process is an urgent task for the timber processing industry. To study the dynamics of the process of sawing wood on a horizontal band saw, it is necessary to create its dynamic model, which is a mathematical description of the interaction of the cutting process and the equivalent elastic system of the machine. The problem of the quality of wood sawing is both the accuracy of processing and the roughness of the surface to be processed. To assess the accuracy of wood sawing, two indicators were used: average and maximum undulation. As a result of the research, a new design of the band saw was developed using a dynamic model, which ensures resource saving, reducing the energy intensity of the technological process and improving the quality of the resulting saw products.

APPLICATION OF PHOTOMETRY IN DETERMINING THE DUST MASS CONCENTRATION OF HARDWOODS

Given the carcinogenicity of hardwood dust, the aim of this study was to determine the effectiveness of the photometric method for different types of woodworking machines and its application in determining the mass concentration of inhalable dust for raw and dry hardwoods. In addition to the optical part of the device, the input part of the measuring device contains the Institute of Occupational Medicine (IOM) inhalable dust filter holder. This correlation of gravimetric and photometric methods in determining the dust mass concentration showed that photometry underestimates the mass concentration measured gravimetrically. The results of this study recommend the application of a correction factor 2 for a timber band saw and a correction factor 3 for circular saws in determining the mass concentration of hardwood dust by the photometric method. It was showed that photometry can be used if the correction factor of the optical device has been previously tested for specific wood processing place.

Preparation Methods for Lower Bainite after a Continuous Austempering Treatment of Thin Sheets of the Eutectoid Cold Work Steel 80CrV2 (1.2235)

Strip material with a thickness of 0.85 m was austempered in a suitable continuous hardening furnace for the further development of blade body steels used for thin-cutting circular and band saw blades. This work also comprised the search for a rather straightforward metallographic preparation procedure allowing for a reliable identification of the microstructure and microstructural constituents. The prepared microstructure can be revealed using Nital or Beraha and LePera etching solutions. None of the three etchants allows a reliable and reproducible distinction of the microstructural constituents of the extremely fine-grained lower bainite using light-optical techniques. Only the use of the scanning electron microscope at higher magnifications allows a reliable identification of the characteristic bainite fiber bundles. For this examination, etching with Nital is recommended.