Roller Profiling for Shaping Corrugated Profiles on the Heat Exchanger Tape for Wind Tunnels

The efficiency of regenerative heat exchangers with heat-accumulating nozzles made of rolled corrugated tapes depends on the profile of their corrugation. It is technologically difficult to obtain corrugations of a given shape by copying --- stamping. It is technically more expedientto form such a profile by rolling between two rollers. The contact area is smaller, and the contact pressure is significantly higher. In this case, the shape and accuracy of the tape profile are determined by the accuracy of calculation and manufacturing of the profile of the rollers. The length of the profiling zone and the contact pressure depend on the diameter of the rollers. To apply the known profiling techniques when calculating the corrugated profile of the rollers, it is necessary to find the position of the centroid. However, the difficulty is in the tape between the rollers whose thickness cannot be neglected. Therefore, the problem is solved by rolling the roller and the rail smooth, where the tape with a profile formed on it is considered as a rail. The paper introduces a technique of roller profiling taking into account the above factors. When profiling the rollers, the springing of the tape, i.e., elastic aftereffect of plastic deformation, is taken into account. The suitable diameter of the rollers has been determined. The study results in a method developed for calculating the rollers corrugation profile, taking into account the established parameters, i.e., diameters of the centroids and rollers, and the rollers teeth profile correction value, depending on the tape springing during rolling

Elastic aftereffect in the process of asphalt concrete mixture compaction

Asphalt concrete of various brands is mainly used as a road surface. The quality and durability of the coating depends on its density. To achieve the required density of the asphalt concrete pavement, road rollers are used. The working body of the roller is a metal drum or a set of pneumatic tires. The article discusses the process of the asphalt concrete mixture compaction with a smooth metal drum. A rheological model of the force interaction of a smooth drum with a material is adopted, which includes elastic, viscous and plastic elements. The adopted model was corrected taking into account the investigated process of elastic aftereffect that occurs in the asphalt concrete mixture during compaction. The law of behavior of asphalt-concrete mixture with elastic aftereffect is established. A simulation model has been developed to study the behavior of a material in the process of elastic aftereffect. In the course of dynamic modeling, the relationship between the physical and mechanical characteristics of the compacted material with the design and technological parameters of the road roller was established. A statistical analysis of the design parameters of existing models of road rollers has been carried out. The results of the analysis, as well as the obtained dependencies, can be used to designate the technological modes of operation of a set of road rollers when compacting the asphalt concrete pavement of a motor road. Taking into account the elastic aftereffect when assigning the operating modes of the compaction equipment will improve the compaction efficiency, as well as the quality of the resulting coating.

Study of stress-strain state of cold-drawn hexagonal steel rods

The results of the stress-strain state during drawing of hexagonal steel rods are presented. The effect of the drawing die angle and the degree of reduction on the distribution of the stress-strain state parameters and the elastic aftereffect of the deformed metal is studied.

Research the hardness of polymer materials after turning

The paper presents the results of experimental studies to determine the hardness of the treated surface depending on the conditions and machining type of workpieces made of textolite, caprolon and fluoroplastic. The experimental methodology and explanation of the reasons for changing the hardness of the treated surface for the investigated variants of machining the materials are under study. The results of studying the influence of the phenomenon of elastic aftereffect of the polymer materials after workpieces machining are obtained.