Introduction. The article is devoted to the research results on cutting resistance of a road asphalt concrete in the process of the removal of worn coatings by the working elements of milling machines. The relevance of the work is due to the occurring of new brands of asphalt concrete alongside with the use of new types of cutting elements, for which it is difficult to predict the load on the working element when solving the problems of designing new ones and substantiation the operating conditions of the current machines. The purpose. The objective of the study of the interaction of a single cutting element of a road mill with a material at the best fit of speed and geometric parameters of a cutting process with real machines is solved.Materials and methods. The experimental work was carried out by determining the tangential component of a cutting resistance strength, as well as the work of this strength on a pendulum desk using a unit recording equipment. Four different types of asphalt concrete were being destroyed. A two-factor experiment was conducted for each type of the material. The tangential components of a cutting resistance strength depending on the thickness of the cut chips and the temperature of the material were evaluated.Results. As a result of the experiment, the data were obtained that make it possible to reasonably determine the loads on the teeth of road milling machines, to determine a power capacity of the process and the drive power of the working element. It was found that the growth of the tangential component to a cutting resistance strength occurs quite intensively alongside with an increase in the thickness of the cut chips, only at the initial stages of the penetration of the cutter. With an increase in the thickness of the cut chips, the growth of the tangential component to a cutting resistance strength does not occur so intensively. In all cases the temperature of the material has an impact on the value of a cutting resistance strength, but this effect is less significant for asphalt concrete with a higher crushed stone content.Discussion and conclusion. The obtained data make it possible not only to determine the tangential strength to cutting resistance on the cutting elements of the working element of the milling machine, but also to find rational ways to place the cutting elements on the working element, as well as to determine the rational operation conditions of the current and new machines. This is possible when using the results in a mathematical model that describes the operation of the milling working element as a whole.Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.
Introduction. The article is devoted to the results of a study of the cutting resistance of road asphalt concrete in the process of removing worn coatings by the working bodies of milling machines. The relevance of the work is due to the emergence of new grades of asphalt concrete and new types of cutting elements, for which it is difficult to predict the loads on the working body when solving the problems of designing new and justifying the operating modes of existing machines.Purpose. To calculate the parameters of the working body of the road milling machine.Materials and methods. The experimental work was carried out by determining the horizontal and vertical components of the resistance force of cutting asphalt concrete. The research was carried out on a mechanical stand with a movable plate, using recording equipment. Four different grades of asphalt concrete were destroyed. A twofactor experiment was conducted for each brand of material. The horizontal and vertical components of the cutting resistance forces were determined depending on the chip cross-sectional area, the grade of asphalt concrete and the type of cutting element.Results. As a result of the experiment, data were obtained that make it possible to reasonably determine the loads on the working body of the road milling machine. It is proved that the dependence of the cutting resistance forces on the chip cross-sectional area of the cutting element has a nonlinear character. The data obtained allow to comprehensively answer questions concerning the justification of the parameters of road milling machines.Discussion and conclusion. The obtained data allow to develop a mathematical model of the asphalt concrete milling process which will make possible to determine not only the loads on the working body and the energy intensity of the process, but also to reasonably approach the placement of cutting elements on the drum, determine the rational range of equipment operating modes and solve the problems of choosing operating modes depending on the type of asphalt concrete.
The paper reflects the results of the study conducted to determine how a free rotary instrument cuts narrow joints in asphalt pavements required for road construction. Based on the analysis of strength characteristics of different asphalt concrete grades, we developed a mathematical model of working process, and this model stands as the calculation basis. The mathematical model associates the main parameter — cutting resistance force — with the material strength values and geometrical characteristics of the working body and the working process. The results of experimental confirmation of mathematical model reliability are presented in the paper.
Introduction. This article presents the results of a study of the wear out effect the carbide tip for the cutting element of a milling machine on the resulting cutting strength when milling asphalt concrete. The relevance of the work is due to insufficient information about the wear out effect on the strength of cutting resistance, and, consequently, it is not possible to predict changes in loads on the working body of milling machines during its operation with worn cutting elements.Materials and methods. The experimental studies to determine the cutting resistance force that occurs during the milling of asphalt concrete with a maximum mineral aggregate size of 16 mm. used for the top layer of the coating and for roads with normal traffic conditions (A16vn), depending on the thickness of the chip being cut and the degree (percentage) of wear of the cutting element were carried out. To conduct the study, a pendulum stand, which is most suitable for studying the interaction of a single cutting element of a road milling cutter with asphalt concrete, was used.Results. As a result of experimental studies, it was possible to obtain the data allowing a reasonable approach to the choice of the interval of replacement of cutting elements during the operation of milling equipment, which, in future, will lead to an increase in the productivity of equipment and its service life. The achieved results make it possible to adjust previously obtained mathematical models and calculation methods of milling machines, taking into account the degree (percentage) of wear of cutting elements.Discussion and conclusions. The conducted studies make possible to determine the dependence of the cutting strength on the percentage of wear of the cutting element and the thickness of the chip being cut. At the same time, it can be concluded that in practice it is necessary to set additional safety margins when designing elements of a milling machine, taking into account the wear of the cutting element.
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