Experimental study of the characteristics of the circular saw cutting unit linear electric drive

Широкое применение круглопильных станков в лесопильной и деревообрабатывающей промышленности обусловлено их высокой производительностью, простотой, надежностью конструкции, низкой энергоемкостью. Для повышения полезного выхода пилопродукции применяют тонкие пилы. Существенным недостатком, ограничивающим использование таких пил, является их недостаточная жесткость и устойчивость во время работы. Для повышения изгибной жесткости круглой пилы применяются щелевые, роликовые, аэростатические и электромагнитные направляющие. Большинство направляющих создают сопротивление вращению диска пилы. К недостаткам круглопильных станков следует отнести механические потери при передаче крутящего момента от двигателя диску пилы. Колебания диска круглой пилы во время работы являются еще одним недостатком тонких круглых пил, которые снижают качество обработки древесины, приводят к поломкам пил и повышенному уровню шума. Для увеличения надежности узла резания, стабилизации диска пилы во время работы, уменьшения колебаний пильного диска предложено использовать линейный асинхронный дугостаторный двигатель (ЛАДД), ротором в котором является сама круглая пила. Для проверки разработанной математической модели ЛАДД с круглой пилой в качестве ротора была создана экспериментальная установка. Целью работы явилась экспериментальная оценка математической модели и анализ рабочих и механических характеристик ЛАДД, характеристики холостого хода и короткого замыкания двигателя, зависимости мощности и cos ϕ от скольжения. Экспериментально установлено влияние электропроводности диска пилы на эффективность ЛАДД. Для увеличения тягового усилия предложено нанести на боковые поверхности диска пилы материал с высокой электропроводностью (медь). Проведенный эксперимент показал существенное увеличение тягового усилия для диска пилы с покрытием медью. Установленная экспериментально величина магнитной индукции в воздушном зазоре ЛАДД показала корректное совпадение с результатами расчетов по разработанной математической модели. The circular saws are widespread in sawmill and woodworking industry due to their high productivity, simplicity, design reliability, and low energy consumption. Thin saws are used to increase the effective yield of sawn timber. The insufficient rigidity and stability during operation of such saws limit their use. Slotted, roller, aerostatic and electromagnetic guides are applied to increase the bending stiffness of a circular saw. Most such guides create resistance to the rotation of the saw blade. Mechanical losses during the torque transmission from the motor to the saw blade is one of the circular saws disadvantages. Another disadvantage of thin circular saws is vibration of the circular saw blade during operation, which reduce the quality of wood processing, lead to the saw crashes and increased noise levels. It is proposed to use a linear induction arc-stator motor (LIASM), implementing the circular saw is the rotor, to increase the reliability of the cutting unit, stabilize the saw blade during operation, and reduce the oscillations of the saw blade. The experimental setup was created to analyze the developed mathematical model of a LIASM with a circular saw as a rotor. The aim of the work is the experimental evaluation of the mathematical model and the analysis of operating and mechanical LIASM characteristics, idling and short-circuit characteristics of the motor, the dependence of power and cos ϕ on slip. The influence of the saw blade electrical conductivity on the efficiency of the LIASM has been experimentally established. It was proposed to apply a material with high electrical conductivity (copper) on the side surfaces of the saw blade to increase the tractive effort of the drive. The carried-out experiment showed a significant increase in the tractive effort for a copper-coated saw blade. The experimentally established values of the magnetic induction in the air gap of the LIASM showed good coincidence with the calculated results from the developed mathematical model.

Analysis of the vibratory cultivator operation

Vibration can significantly reduce the pulling force of machines. The crushing of the soil increases with the frequency of vibration of the organ, and it was found that the size of the pieces of soil depends on the ratio of the speed of the aggregate to the frequency of vibration of the organ. In addition, traction and fuel consumption are reduced compared to machines without vibrating implements. Reduced tractive effort is the most important indicator of the effectiveness of the use of vibrating tools. The purpose of the study is to study the effect of applying vibrations at different frequencies to a cultivator on its performance, as well as oscillatory motion at two frequencies and with constant amplitudes on the traction force of the working body and soil properties. It can be noted that the effect of vibration frequency on tractive effort is more important than the depth of tillage. These two factors are the main and most significant in terms of tractive effort. Working depth also has a significant effect on tractive power. It increases to 54% with an increase in the working depth from 100 to 200 mm. The result is the same with a depth of 300 to 400 mm. An increase in tractive effort occurs due to a higher additional soil pressure and an increase in frictional forces in the "soil-metal surface of the working body" system. Keywords: TILLAGE; OSCILLATORY MOVEMENTS; LOOSENING THE SOIL; VIBRATION

Estimation of ballasting tractors 5-6 traction classes

To increase productivity in agricultural production, combined wide-grip machines are being created, aggregated with tractors of traction classes from 5 and higher. In addition, according to agrotechnical requirements, the pressure of the mover on the soil should be minimal, as well as the number of passes over the surface of the field. These contradictions can be solved by ballasting of tractors, which allows using engine power to increase tractive effort. Ballasting affects energy saturation. Increased energy saturation with appropriate ballasting makes it possible to compose machine-tractor units (MTU) according to a more accurate ratio of the tractor pulling force and the unit's pulling resistance. The most in demand in modern agriculture are tractors of 5-6 traction classes produced by domestic and foreign tractor-building plants with an internal combustion engine with a capacity of 220-320 kW and an operating weight of 115-150 kN. The article contains a two-way analysis of variance, which makes it possible to determine the greatest influence on the ballasting of a tractor. A diagram is constructed that gives an idea of which of the studied brands of tractors can be recommended for performing agricultural operations, taking into account ballasting and compliance with agrotechnical requirements. Keywords: TRACTOR, BALLASTING, ENERGY SATURATION, TWO-FACTOR ANALYSIS OF VARIANCE

DC RAILWAY POWER FLOW ANALYSIS FOR ADDIS ABABA LIGHT RAIL TRANSIT USING NEWTON RAPHSON METHOD

This paper uses Newton–Raphson method for DC power flow analysis of the Addis Ababa light Rail Transit (AALRT). The study focuses onthe line section from Menilik II square station up to Lideta station. First the tractive effort required by the trains for different scenarios such as train movement in a straight line, a curved line, and a line with gradient is computed as the chosen line section contains all these scenarios. Then the total input power will be calculated using computed tractive effort obtained for each scenario and using other input parameters obtained from AALRT, and different papers. The input power for the different loads is computed, and the input power is used to analyse the bus voltage for different loads and train positions. Newton Raphson Method is used to solve the DC Power bus problem assuming that the train requires constant power while moving between two feeding stations. Even if using the rail as the return conductor for DC traction systems has economic advantages, it has some limitations like the rail potential and stray current. A rail potential study is carried out and conclusions are drawn. The result shows that the maximum voltage drop was 0.1 p.u and the train power consumption increases by 136.73 kW as the train takes a gradient of 3.92% and keep increasing again by 29.17kw with a curve resistance (100 meters). The Rail potential moves from 6.0139V to 29.85V proportionally with the variation of the total ground resistance.

Individual Drive-Wheel Energy Management for Rear-Traction Electric Vehicles with In-Wheel Motors

In-wheel motor technology has reduced the number of components required in a vehicle’s power train system, but it has also led to several additional technological challenges. According to kinematic laws, during the turning maneuvers of a vehicle, the tires must turn at adequate rotational speeds to provide an instantaneous center of rotation. An Electronic Differential System (EDS) controlling these speeds is necessary to ensure speeds on the rear axle wheels, always guaranteeing a tractive effort to move the vehicle with the least possible energy. In this work, we present an EDS developed, implemented, and tested in a virtual environment using MATLAB™, with the proposed developments then implemented in a test car. Exhaustive experimental testing demonstrated that the proposed EDS design significantly improves the test vehicle’s longitudinal dynamics and energy consumption. This paper’s main contribution consists of designing an EDS for an in-wheel motor electric vehicle (IWMEV), with motors directly connected to the rear axle. The design demonstrated effective energy management, with savings of up to 21.4% over a vehicle without EDS, while at the same time improving longitudinal dynamic performance.

Digital Data Processing Methods for Estimating Tractive Force of Tractors

Introduction. When carrying out an energy assessment of agricultural machines and traction tests of tractors, the most important indicator is the value of the tractive effort. The existing methods for determining the tractive effort of tractors imply the use of specialized measuring instruments, such as strain gauges and devices for processing and displaying information. The accuracy of determining the tractive effort is significantly influenced by the physical and mechanical properties of soil. To process the useful signal during the measurement of tractive effort, the data stream of the strain gauge sensor must be subjected to additional digital filtering taking into account the operating conditions of the agricultural unit. Materials and Methods. The functions of changing the tractive effort obtained on the K-744R2 tractor in various gears have been analyzed. An algorithm for digital processing of the signal of a strain gauge force meter based on a median filter has been developed that makes it possible to increase the measurement accuracy. The advantage of the proposed method is the ability to cut off sharp short-term impulse noise and sharp fluctuations in the amplitude of the measured value. Results. A method for determining the amount of tractive effort using median signal processing has been proposed. A device for determining the tractive effort during testing of agricultural tractors and units has been developed. The choice of the main components of the device for determining the magnitude of the tractive effort has been substantiated. As a result of the research, a device for measuring and digital processing of the signal of a force meter based on a microcontroller and specialized software for processing initial data in real time was designed and manufactured. Discussion and Conclusion. The developed method makes it possible to exclude the negative effect of impulse noise arising in the process of measuring the tractive effort of the tractor. The proposed device for measuring the tractive effort of tractors is compatible at the level of the exchange protocol with existing devices, has a high speed of operation in real time, multi-channel operation.

INCREASING THE TRACTIVE EFFORT OF FOREST WINCHES DURING LOADING AND UNLOADING OPERATIONS

The article analyzes the operation of various friction devices in order to select the most appropriate design for use on winches on a road train when performing loading and unloading operations. International experience in the operation of forest winches has shown that the most commonly used winches are disk, cone, pad-pneumatic friction clutches and external belt types. Due to the increase in the length of the transmitted torque and the reliability of the couplings, it is possible to significantly increase the pulling forces of winches without significantly changing the designs of other nodes.

Resistive Force Analysis for Design of Rubber Tire Loader Buckets

Rubber tire loaders are key loading equipment for surface and underground mines and can load up to 35 t of material in a pass. Efficient initial penetration into the pile improves the overall efficiency of the loading operation. For efficient design for good initial penetration, we need to predict accurately the resistive forces encountered by these buckets during initial penetration. This paper examines the resistive forces on the bucket as a function of rake angle, height above the digging floor, speed, and tractive effort during initial penetration. A 1/16th scaled representative model of an 18 t (19.8 ton) capacity load haul dump is used for experimentation to understand the effects of rake angle, height above the floor, speed, and tractive effort. The results show that resistive forces are not associated with rake angle or height above the floor but significantly associated with speed, tractive effort, combined effects of speed and tractive effort, and combined effects of speed and rake angle. Future research should focus on conducting similar experiments on different materials and different buckets to better understand the ground engagement for mining and construction equipment. These insights are important to understand the full range of forces during bucket and equipment design.