Improvement of the Design of the Unit for Automatic Graded Spreader

Abstract

Surface treatment is widely used to provide the required parameters of roughness and wear resistance of road surfaces. To ensure the quality of surface treatment, the time gap between the application of a binder layer on the surface of the roadway and the further distribution of crushed stone over it should not exceed one second. For such a synchronous distribution of binder and crushed stone, bitumen-split distributors (BSC) are used. When using crushed stones of different fractions, it is important to ensure the quantitative ratio of the components and their thorough mixing. Known BSC with a plane-oscillating distribution unit does not provide a dosed separation and mixing of crushed stone of different fractions. In the article, based on the analysis of the operation of the main functional units of the BSC, an original design unit for the dosed extraction and mixing of different-fraction crushed stone in the form of a rotating gate interacting with the blades of a rotating drum is proposed. The main situations in the variation of the mutual position of these synchronously rotating parts are empirically revealed. Thus, it has been established that the dominant factor determining the quantitative ratios of different crushed stone fractions in the mixture is the accuracy of the relative position of the shutter working surface relative to the rotation trajectory of the peripheral sections of the drum blades. The article analyzes the accuracy of the relative position of the shutter and the petals of the drum, and to compensate for the identified displacements of the centers of their rotation, a modernized design of the crushed stone distribution unit is proposed. On the basis of experimental studies on a special stand, the operability of the proposed design of the crushed stone distribution unit was confirmed, the influence of the shutter opening degree on the crushed stone emptying time was investigated, and further directions in the creation of new designs of crushed stone mixing and distribution units were indicated, including when operating as part of automatic control systems for the process of bitumen and crushed stone distribution.
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