DETERMINATION OF A TECHNICAL CONDITION OF THE EQUIPMENT OF THE LINE OF A DRIVE OF ROLLING ROLLS ON THE SPEED OF PROPAGATION OF THE SHOCK PULSE

One of the ways to determine the technical condition of the equipment of the line working rolls - spindles - gear cage - root coupling - reducer - intermediate shaft - engine is considered. In each connection there is wear of contact elements, for example, bronze inserts of spindles, teeth of gears. According to the known method, the amount of current wear of the elements and the gaps caused by them at the same time is determined by the time of delay of the reaction of sections of the line to the impact load during the capture of the strip by rolls. The greater the wear, the longer the delay time. The option of determining the state of the nodes of the line by determining the speed of propagation of the shock pulse from the rolling stand to the engine is considered. An example of measuring the reaction delay time of three sections of one of the stands with calculations of the pulse rate in these sections is given. It is shown that with increasing wear, the pulse velocity decreases significantly. Therefore, this speed characterizes the technical condition of the sites, ie has a diagnostic feature. Additionally, the influence of the presence of oil, scale, and contamination in the joints is considered. It is also recommended to use the ratio of the base speed of the shock pulse in the solid shaft to the actual speed in the nodes to determine their technical condition.

Bridges maintainability evaluation peculiarities as part of hydraulic structures

Introduction: the article is dedicated to assessing the condition with respect to use for traffic methods of bridges as part of hydraulic structures (dams, hydroelectric power stations, locks). The main factors affecting the structural element’s durability included in the composition of the hydraulic structures are dynamic loads (applied repeatedly and repeated) affecting the bay due to the hydrodynamic effect; temporary, moving loads from passing highway transportation, along the top of the structure (along the roadway); harmful chemical impurities contained in the water passing through the structure. Under the influence of the above-mentioned factors, defects and damage occur in the hydraulic facilities’ structural elements. Methods: the authors assessed the actual state of the material of the operating structure. To assess structures and materials actual state during the bridge structure inspection work, the following instrumental measurements were performed on as-built structural elements: leveling the top of the sidewalks and the roadway; materials strength determination of the main supporting structures by nondestructive methods; thickness measuring the asphalt concrete pavement of the roadway; determination of the degree of carbonation of concrete; identification of defects in the elements of the bridge. The actual structure’s concrete strength was determined by nondestructive testing methods: (1) by the method of the elastic rebound; (2) by the shock pulse monitoring method; (3) an indirect method of concrete strength ultrasonic testing based on the revealed relationship between the method of separation with shear test and methods – shock pulse and elastic rebound. Results: technical condition and bridge safety indicators calculation as a hydraulic structure element was executed. Discussion: technical examination results of the bridge structural elements and instrumental studies confirm the conclusion about the repair measures need with high-strength concretes and protective coatings based on polymer composite materials. Final report: following the emergency scenarios a numerical estimate table for the quantitative and qualitative parameters list was made, parameters corresponding to a particular structure state. Thus, according to the scenario related to the 3rd accident group, the bridge technical condition is assessed as limited operable, and the safety level is reduced.

Segregation of the bulk cargo on a belt conveyor under the vibro-pulse impact

The dynamics of interaction of the large lumps of the bulk cargo with a conveyor belt while passing through roller supports of the conveyor linear sections is often a cause of damage on the conveyor belt. In order to reduce the negative impact it is proposed to isolate the conveyor belt surface from the large lumps by filling small fractions of the bulk cargo by means of adding a shock device to the conveyor structure that causes increased segregation of the bulk cargo. A mathematical model of the segregation of the bulk cargo located on the conveyor belt and in zone of impact of the shock pulses has been developed. The model considers a change in the rotation direction of the large lump when applying shock pulses to the characteristic points of the lump lower face. Herewith it takes into consideration weakening of the shock pulse by a layer of the bulk cargo small fractions. The presented model has received experimental confirmation. Analytically and experimentally the height of filling of the bulk cargo small fractions under a large lump when passing the vibrating impact device located on the conveyor belt has been determined.