EXPERIMENTALSTUDY OF DYNAMIC EFFORTS DURING THE OPERATION OF THE MECHANISM OF MOVEMENT OF THE CARGO TROLLEYOF AN OVERHEAD CRANE

The article deals with the determination of the dynamic loads arising in the running wheels of a conventional (standard) and modernized design during the movement of the cargo carriage of an overhead crane. The redesigned wheel has an insert made from 7-7130 rubber compound. Also, a method for diagnosing running wheels of conventional and modernized design was determined. The ZETLAB program was chosen as a program for signal registration and analysis. This program allows not only displaying the signal in real time with the possibility of scaling, but also allows you to digitize the signal with the possibility of further processing the results in various standards. Finding out the occurrence of a defect in wheels and rails is mainly carried out by two methods, when shock pulses appear and according to an increased background of vibration. In practice, there is a process of "dry" rolling friction, and this means that the method of shock pulses for diagnosing the condition of wheels and a rail track can be used only in some cases in the form of extreme wear of the friction pairs of a wheel and a rail. That is, the method of spectral analysis of fluctuations in the power of random vibration can be successfully applied to diagnose the state of the rail track and crane wheel. The diagnostic method based on the overall vibration level allows for an overall assessment of the technical condition. Such diagnostics makes it possible to identify defects only at the very last stage of development, when they lead or have already led to partial destruction of the rolling surface of the wheel and the surface of the rail, that is, to an increase in the overall level of vibration. The performance evaluation criteria are fully focused on the corresponding standard vibration levels for the investigated friction pair. A friction pair is considered to be defective, the vibration of which exceeds the general standard. When determining an increased overall level of vibration, maintenance personnel must make a decision to replace parts or a unit to prolong its operation. The results obtained indicate the advisability of using the wheels of the modernized design on the cargo carriage of an overhead crane.

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.

Kinetic energy at collision of two automobiles

At collision of two automobiles under the influence of shock pulses the change of their speed occurs. The dynamic characteristic of movement of mechanical system consisting of two automobiles includes traffic, kinetic moment regarding motionless centre and kinetic energy. On the basis of dynamics theorems the author has determined a loss of kinetic energy of central-straight collision of two automobiles. The paper considers specific cases — elastic and absolutely inelastic collisions. It is established that at elastic collision the kinetic energy decreases by the amount of kinetic energy of lost velocities with amendment that includes a coefficient of recovery at collision.

ИССЛЕДОВАНИЕ ВЫГРУЗКИ ТРАНСПОРТНЫХ СРЕДСТВ ПРИ УБОРКЕ КАРТОФЕЛЯ

Уборка картофеля предполагает транспортировку клубней с поля до хранилищ. Транспортные средства для перевозки картофеля весьма разнообразны и разнотипны это и автомашинысамосвалы, тракторные самосвальные прицепы, автомашины с полуприцепами и контейнеровозы. В большинстве картофелеводческих хозяйств площади, занятые под картофель, не превышают 300 га, а для транспортировки урожая применяют большегрузные самосвалы. Выгрузка картофеля из кузова происходит в результате подъемаопрокидывания, что приводит к образованию гравитационных потоков клубней и способствует появлению механических повреждений клубней. Взаимодействия клубней при выгрузке генерируют напряжения в насыпи картофеля за счет передачи ударных импульсов. В работе исследуется процесс скатывания одиночных клубней по насыпи картофеля. Анализ движения единичных клубней по насыпи показал, что качение клубня происходит при достаточной силе трения под углом естественного откоса. Наибольшее влияние на кинетическую энергию системы будет оказывать путь, пройдённый клубнем по насыпи чем больше путь, тем больше энергия. Значительную роль будет оказывать также конечная скорость клубня. Снизить кинетическую энергию клубня можно, уменьшая участок разгона с помощью установки дополнительных препятствий в кузове, например, поперечной перегородки. Для уточнения теоретических выкладок был проведен эксперимент по выгрузке клубней из контейнера без перегородки и оборудованного поперечной перегородкой. В ходе эксперимента изучались раскат клубней от контейнера, характеризующий скорость клубней при скатывании по насыпи, и остаток клубней в кузове, характеризующий скорость выгрузки клубней. Установлено, что дополнительные поперечные перегородки способствуют снижению кинетической энергии картофеля при выгрузке и снижают механические повреждения клубней.Harvesting potatoes involves transporting tubers from the field to storage. Vehicles for transporting potatoes are very diverse and diverse these are dump trucks, tractor dump trailers, trucks with semitrailers and container carriers. In most potato farms, the area occupied by potatoes does not exceed 300 hectares, and heavy trucks are used to transport the crop. Unloading of potatoes from the body occurs as a result of lifting tipping, which leads to the formation of gravitational flows of tubers and contributes to the appearance of mechanical damage to tubers. The interactions of the tubers during unloading generate stresses in the embankment of the potato due to the transmission of shock pulses. We investigate the rolling of single tubers over a mound of potatoes. Analysis of the movement of individual tubers along the embankment showed that the tuber rolls with sufficient friction at an angle of repose. the kinetic energy of the system will be most affected by the path traveled by the tuber through the embankment the larger the path, the greater the energy. The final speed of the tuber will also play a significant role. Reducing the kinetic energy of the tuber, it is possible to reduce the acceleration area by installing additional obstacles in the body, for example, a transverse partition. To clarify the theoretical calculations, an experiment was conducted to unload tubers from a container without a partition and equipped with a transverse partition. During the experiment, the tuber roll from the container was studied, which characterizes the speed of the tubers when rolling along the embankment, and the remainder of the tubers in the back, which characterizes the speed of unloading the tubers. Additional transverse partitions have been established that contribute to a decrease in the kinetic energy of potatoes during unloading and reduce mechanical damage to tubers.

Investigation of the influence of the geometrical dimensions of the striker on the efficiency of energy transfer of shock pulses during wave strain hardening

The article presents data on the influence of the geometric parameters of a flat-faced rod shock system on the efficiency of a shock pulse energy transfer to the deformation zone during wave strain hardening. As a result of the simulation, it was found that an increase in the ratio of the striker length to its diameter from 0.1 to 10 allows transferring 15.6 times more shock pulse energy to the deformation area. Changing the ratio of the lengths of the striker and the waveguide from 0.1 to 10 increases the share of the transmitted shock pulse energy by 2.8 times.