Dragline Excavators Research Articles

Study on Heavy Machinery Utilizing the Most Recent Technologies for Excavation of Road Construction and Mining

An essential component of the nation's overall development is its infrastructure development. India is regarded as the centre of the service sector, where infrastructure development is crucial. The main issue is what contractors usually have when choosing the best equipment. Given the circumstances, a contractor's inquiry would likely focus heavily on machinery and plants' upkeep and operating costs. Due to the substantial capital required for the purchase, rental, lease, and operation of the plant and equipment, it must be managed to maximize return on investment, and productivity, and minimize operating, maintenance, and repair costs. Therefore, careful planning and selection are necessary to ensure that the project is completed successfully. The kind of apparatus chosen typically relies on the properties of the material to be worked with. Using tracks or wheeled equipment; power or dragline excavator use a shovel, among other common inquiries that should be responded to by the construction equipment planner.

Substantiating the rational parameters for a complicated non-transport system when mining low-thickness fireclay deposits

The paper examines a complicated non-transport system for mining a gently sloping fireclay deposit using ESH-10/70 dragline excavators. The research purpose is to substantiate the technological scheme of stripping operations and determine their parameters to reduce the strip-mining costs. Theoretical research is performed using the following methods: methods of scientific analysis of theoretical research, as well as practices of project and production organizations; mining-geometric calculations; variant method for comparing and selecting a mining system. As a result, the dependence of the excavator block mining velocity on the entry way width has been determined, which makes it possible to study the relationship between mining and stripping equipment in time. The change in the re-excavation coefficient depending on the width of the dragline excavator entry way has been studied and its rational value has been determined. The practical value of the research results is in the substantiation of an effective system for mining a gently sloping fireclay deposit.

Climatic influence on productivity of walking excavators and bulldozers in stripping in gold placer mining

The state and mineability of placer gold reserves and resources in the Russian Federation is reviewed. Judging from wide application of dragline excavators in peat cutting, it can be effective to use draglines in placer mining at depths up to 50 m due to the much lower cost of stripping compared to the other methods. In this case, it is possible to apply various schemes of direct dumping and wider employment of draglines in actual mining. It is noted that one of the highest influences on productivity of draglines and bulldozers during stripping is the presence of seasonal and perennial frost. Two groups of factors to decrease productivity of walking excavators and bulldozers at negative air temperatures are proposed. The conclusions are made about the difficulty of determining frozen ground cuttability due to the peculiarities of overburden sediment formation and because of deficient detailed studies into the properties of rocks, which govern their strength characteristics during freezing. The less labor-intensive method of calculating productivity reduction of walking excavators and bulldozers during stripping is proposed as the determination of hourly productivity reduction patterns by mathematical methods describing the random nature of phenomena, in particular, by the correlation method. The equations of the hourly productivity reduction of draglines and bulldozers depending on average monthly negative air temperature and the hourly capacity reduction factor as function of seasonal permafrost thickness and perennial permafrost cross-sections in overburden face are derived. It is noted that seasonal freezing governs reduction in productivity of excavators and bulldozers at the beginning of the warm period of the year until the permafrost is completely thawed. Stefan’s formula is suggested, according to which it is possible to calculate the depths of seasonal freezing of peat depending on the average monthly air temperature quite reliably.

Automatic control system for walking dragline excavator digging

This paper presents the results of the development of automatic control systems for walking dragline excavator digging process. The process enables operational productivity to be enhanced through optimizing digging process. This also prevents extreme loads on machinery and hoist cable deflection. The paper also describes mathematical models of the electric drives of the main excavator machinery which form the bucket motion and the model of cable length change. Further the study will analyse the tructure of the control system and the automatic digging algorithm. Computer modeling findings are also described to confirm the operability of the automatic digging algorithm. Computer simulation of the processes in electric drives of main machinery of a walking dragline in digging operations was performed by means of SimInTech software. The automatic control system optimizes digging trajectory with very fast penetration with permissible overregulation following digging at a constant cut depth. The integrated system of dragline operation process control is practically independent due to the following factors: the automatic digging control system in combination with automatic systems for transporting the loaded bucket to dump and the empty bucket to the face; the automatic main machinery overload protection systems; and the system of control over safe bucket movement in the dragline working space.

Analytical description of the process of operation of the hydraulic drive of the three-bearing walking mechanism of a dragline excavator

In the paper, an analytical formula is derived that allows to determine the acceleration of the movement of the piston of the hydraulic system at any moment of time. For the purpose of conducting the analytical studies, the most common dragline excavator used in surface mining operations, equipped with a hydraulically driven three-bearing walking mechanism, is selected. The derived formula has the form of the Cauchy formula and is solved on a computer by the Runge-Kutta method of the fourth order, which makes it possible to design the operation of the hydraulic system of the walking mechanism of an excavator-dragline and determine the speed of movement of the walking mechanism at each moment of time throughout the entire step. Keywords: hydraulic drive, dragline excavator, threebearing walking mechanism, differential equations in the Cauchy form, design. Stas_chernuhin@mail.ru

Use of Energy from Pneumatic Hydroaccumulators in the Process of Moving a Dragline Excavator

Use of Energy from Pneumatic Hydroaccumulators in the Process of Moving a Dragline Excavator

Structural Health Monitoring of Walking Dragline Excavator Using Acoustic Emission

The article is devoted to the organization of the structural health monitoring of a walking dragline excavator using the acoustic emission (AE) method. Since the dragline excavator under study is a large and noisy industrial facility, preliminary prospecting researches were carried out to conduct effective control by the AE method, including the study of AE sources, AE waveguide, and noise parameters analysis. In addition, AE filtering methods were improved. It is shown that application of the developed filtering algorithms allows to detect AE impulses from cracks and defects against a background noise exceeding the useful signal in amplitude and intensity. Using the proposed solutions in the monitoring of a real dragline excavator during its operation made it possible to identify a crack in one of its elements (weld joint in a dragline back leg).

Технология укладки бентонитовых матов на канале в сложных условиях производства работ

Purpose: the technology of laying geocomposite bentonite mats with the creation of an anti-filtration lining of increased reliability on the main canal section made under difficult conditions (in the presence of karst and suffusion phenomena) is considered. Materials and methods. The theoretical basis of the research is the indicators of physical, mechanical and technical characteristics of bentonite mats of various manufacturing companies. The practical component is flow charts, diagrams and technology for the work performance in natural conditions on the main canal section. Results and discussion: to reduce the filtration coefficient of anti-filtration coatings it is advisable to use two- and three-layer materials, which were used in the reconstruction of the Donskoy main canal section instead of polymeric materials, according to the results of the feasibility study. The work on laying sodium bentonite mats was carried out in difficult conditions after stopping the water supply, when there was an intense slope sloughing, and the water level in the canal was set below the groundwater level in the canal zone. At the same time, the canal was periodically cleaned with a dredger to remove the swollen soil along the canal bottom, and on the slopes – excavation with a dragline excavator, followed by transportation and soil storage in the slurry dump maps. Further, the work was carried out on maps with pools, separated by dams, where map sections were drained by a mobile pumping station. Conclusions: the use of the developed technology for canal cleaning and laying roll materials based on bentonite made it possible to reconstruct successfully the most dangerous canal sections. The introduction of a structural and technical solution in the form of a combined screen design ensures almost complete water imperviousity of the bottom and slopes of the canal.

Experimental mining of three coal seams by transportless technology

In conditions of market economy and competition it is of great importance to reduce the cost of coal mining. It is especially important when mining coal at the complicated deposits of Kuzbass. In these conditions it is important to choose the technology of stripping and winning works, providing a minimum cost for them. There are two essential factors for achieving this goal: reduction of expenses on transportation of overburden and expenses connected with alienation of lands for external dumps and their reclamation. Therefore, promising technologies are those that ensure the placement of the maximum amount of overburden in the internal dump. This condition sets the task of expanding the scope and boundaries of application of transportless technology, which is used in Kuzbass both independently and in combination with transport technology. In particular, the combined technology is used at Chernigovets open pit mine, where the upper part of the quarry field, containing Kemerovsky seam, is mined using transport technology. The lower part up to 70 m high, which includes three flat seams: Volkovsky, Podvolkovsky I, Podvolkovsky II, on an experimental basis is mined by transportless technology (the volume of stripping works is 5-10 % of the total volume). A distinctive feature of the experiment is the performance of stripping and winning operations with a single dragline excavator, which eliminates the cost of maintaining the rope shovel and bulldozer. Therefore, the experience of using this technology is of practical interest for other open pits in the basin, as well as for any other quarries with similar mining and geological conditions.

Mathematical modeling of the dragline travel mechanism with sliding supports

The results of an analytical study of the walking mechanisms of dragline excavators are presented. The advantages and disadvantages of the hydraulically driven walking mechanism are considered. Constructive changes are proposed in the form of installation of sliding supports and horizontal arrangement of traction hydraulic cylinders on support shoes. A method for calculating the forces acting on sliding bearings is presented, which makes it possible to determine the requirements for the physical and mechanical properties of the sliding bearings material, including the hardness and wear resistance of their working surfaces. Examples of using the mathematical model of a three-bearing walking mechanism with sliding supports, created in the MATLAB Simulink software environment, are shown.

Justification of dump parameters in conditions of high water saturation of soils

The object of research is the stability parameters of the massif of a single-tier dump of soft overburden rocks with a flooded slope when it is formed by a dragline excavator. One of the most problematic areas is determining the safe distance of the dragline excavator from the upper edge of the slope in the conditions of the formation of a single-tier dump of soft overburden rocks, flooded with water.The calculation of the width of the prism of possible shift was carried out using the Rocscience Slide software, which, taking into account the parameters of the slope and the physical and mechanical properties of the rock mass, automatically restores a number of curved sliding surfaces for individual safety factors. The obtained data were processed using the Microsoft Excel software, thanks to which, by the least squares method, graphs of the functions of the possible shift prism width from the height of the tier of a dump of soft overburden rocks and the level of its flooding were constructed.For the conditions of the formation of a single-tier dump of soft rocks of overburden with a height of 40–100 m and a flooding level of 0–30 m, the width of the prism of a possible shift was calculated for sliding surfaces with a safety factor of 1 and 1.2. These values are, respectively, 0–85.9 m and 0–122.6 m within the established calculation limits and depending on the method of constructing curved surfaces. The distance between the points of intersection of the horizontal surface of the tier with curved sliding surfaces with a safety factor of 1 and 1.2 is 16–52.5 m. The dependences of the width of the prism of possible shift (a) on the height of the tier of a dump of soft overburden rocks (Ho) and its level flooding (Hw), taking into account the physical and mechanical properties of the dumped mountain range, including saturated with water. The minimum deviation from the initial value of the coordinates of the points is achieved when setting the second-degree polynomial as the trend line for the function a=f(Hw), and for a=f (Hо) – a straight line.The obtained data for calculating the parameters of the possible shift prism suggest the possibility of forming a single-tier dump of soft overburden rocks with a height of 40–60 m with unloading of rock mass into the worked-out space and 70–100 m with loading the unstable part of the slope with an EK-11/70 excavator-dragline (Novokramatorsk Machine-Building plant, Ukraine).

Increasing energy efficiency of walker dragline

Relevance of the work. Reducing the cost of mining in the course of open pit mining has always been considered one of the important tasks in the mining industry; it allows to reduce the cost of the extracted ore. When developing quarries, the most costly work, in which there is no direct mining, is the overburden of waste rocks. The method of stripping operations is one of the most efficient and highly productive, which uses a non-transport technology with a walking dragline excavator. Moving such powerful machines is energy-intensive and affects the efficiency of the machine as a whole, therefore, the modernization of the walking mechanism will increase the energy efficiency of the excavator and ultimately reduce the cost of mining. The most common mechanism for moving such machines is a hydraulically driven three-bearing mechanism. This paper describes the proposed modernization of such a walking mechanism, which makes it possible to get rid of two main disadvantages, namely, the lack of energy recuperation of the lifted machine along the path and the dragging of the base edge against the ground, which creates additional resistance to movement. The installation of hydraulic accumulators in the hydraulic system of the drive of the movement of the machine will allow accumulating the energy of the machine raised above the ground when walking, and the introduction of an additional support shoe into the support base of the machine will get rid of dragging the base. In general, the presented modernization of the mechanism will reduce the energy consumption of moving a dragline excavator with a three-bearing walking mechanism with a hydraulic drive and, ultimately, reduce the cost of mining. Purpose of the work: to improve the efficiency of the dragline as a whole by increasing the energy efficiency of its movement. Objectives: consider design changes to reduce the energy cost of moving the dragline. Results. A variant of adding a support shoe into the walking mechanism is considered, which makes it possible to eliminate the friction of the base against the rock along the path by completely separating the base from the ground. Calculations of energy consumption of mechanisms for different types of draglines with the existing and proposed mechanism are carried out. Conclusions, application of results. The calculations given in this paper allow us to conclude about the effectiveness of the changes made to the design of the walking mechanism. The proposed mechanism allows you to significantly reduce the cost of moving and get rid of the disadvantages inherent in the existing mechanism.

Kinematic Analysis of an Under-actuated, Closed-loop Front-end Assembly of a Dragline Manipulator

Dragline excavators are closed-loop mining manipulators that operate using a rigid multilink framework and rope and rigging system, which constitute its front-end assembly. The arrangements of dragline front-end assembly provide the necessary motion of the dragline bucket within its operating radius. The assembly resembles a five-link closed kinematic chain that has two independent generalized coordinates of drag and hoist ropes and one dependent generalized coordinate of dump rope. Previous models failed to represent the actual closed loop of dragline front-end assembly, nor did they describe the maneuverability of dragline ropes under imposed geometric constraints. Therefore, a three degrees of freedom kinematic model of the dragline front-end is developed using the concept of generalized speeds. It contains all relevant configuration and kinematic constraint conditions to perform complete digging and swinging cycles. The model also uses three inputs of hoist and drag ropes linear and a rotational displacement of swinging along their trajectories. The inverse kinematics is resolved using a feedforward displacement algorithm coupled with the Newton-Raphson method to accurately estimate the trajectories of the ropes. The trajectories are solved only during the digging phase and the singularity was eliminated using Baumgarte′s stabilization technique (BST), with appropriate inequality constraint equations. It is shown that the feedforward displacement algorithm can produce accurate trajectories without the need to manually solve the inverse kinematics from the geometry. The research findings are well in agreement with the dragline real operational limits and they contribute to the efficiency and the reduction in machine downtime due to better control strategies of the dragline cycles.

Послеремонтные испытания электрических машин шагающих экскаваторов

Dragline excavators are the main means of mechanization in mining coal fields. The operational reliability and in-use performance of the overburden dragline excavators determine the mining enterprises’ capacity. The aim of the study is to increase the reliability of the excavators’ electromechanical equipment. The main research method is modeling of the electromagnetic processes taking place in the after-repair tests of the excavator’s electric machines. The study has shown that the failures of the mining equipment operating in the northern part of Russia are of both mechanical and electromechanical nature. The failures associated with electromechanical emergency conditions are more often caused by the failure of the direct-current electric machines of the excavators’ main drives. To ensure the high quality of the repair and reduce the risk of failure, all electrical machines must undergo appropriate post-repair tests including those under load. The existing loading methods involve mechanical aggregation of the electric machine with the load devices. It is difficult to implement these methods when testing large direct-current electric machines in the conditions of the repair plants. Obviously, the development of the test methods that exclude mechanical aggregation of the electric machines and load devices is important and promising. Static loading of electrical machines is proposed as one of the above methods. The method implies dividing the test in two stages. In the first stage, static current loading is performed, and in the second stage, dynamic current and mechanical loading are carried out in the modes close to operational ones. The study of the control system developed for the electric drive of the test stand has shown that the system is functional and allows the testing of the direct-current electric machines in full.

Determination of the working area of a hydraulic excavator

The article discusses the mechanisms of walking used on dragline excavators. The disadvantages of each mechanism are identified and based on this, the most promising movement mechanism is selected – a three-legged walking mechanism with a hydraulic drive. For this mechanism, the main disadvantages are also identified. The following is a technical solution that allows you to save this mechanism from the main drawback – the need to raise the center of mass of the excavator to a significant height to ensure the maximum step value. The technical solution includes the presence of a flat hydrostatic support that allows to increase the efficiency of the mechanism in open-pit mining operations. The calculation of oil consumption through a flat hydrostatic support in the conditions of its use on quarry soils with different bearing capacity is made.

Development of engineering approach to the assessment of stress raisers in metal structures of dragline excavators

In the present work, its authors present the new results obtained on the creation and development of an engineering approach to the assessment of stress raisers in the metal structures of dragline excavators, convenient to be applied in the express diagnostics system to test the condition of such machines. The main result of this work is the conclusion that the value of the geometric stress concentration factor for the fillet weld of metal structures of the excavator arm EH-10/70A under working conditions can be written using the Afanasiev formula.

Erratum to: The use of a flat hydrostatic support in the tricycle walking mechanism of a dragline excavator

Erratum to: The use of a flat hydrostatic support in the tricycle walking mechanism of a dragline excavator

Substantiation of the rational installation location of a dragline excavator in the face when working with dump trucks

Substantiation of the rational installation location of a dragline excavator in the face when working with dump trucks

Моделирование системы управления электроприводом подъема экскаватора ЭШ 20.90 при работе в тяжелых горнотехнических условиях

Walking excavators (ESH) are the main mechanization means when developing coal fields in the regions of Siberia. The operational reliability and in-use performance of overburden dragline excavators determine the mining enterprises’ capacity. The previous studies show that a large percentage of the failures of the mechanical equipment used in opencast mining is connected with the draglines. Reduction of the dynamic load in the kinematic elements of the ESH 20.90 lifting drive increases the operational reliability of the excavators operating in arduous conditions. The statistical analysis has shown that most of the excavators’ breakdowns are connected with the failures of their traction and lifting mechanisms. Therefore, to increase the draglines’ reliability, it is necessary to limit the load on the kinematic elements of the mechanical structure in the periods of the year with a significant temperature gradient. For this purpose, a standard closed-loop control system of the lifting electric drive has been modelled. The modelling has shown an unacceptable level of the dynamic loads arising in the kinematic elements of the excavators operating at low temperatures. As a result, an advanced lifting drive control system for the ESH 20.90 excavator has been developed. The system allows to control the engine torque by the speed, and to stabilize the sustained power of the drive. The study has shown that the suggested system significantly reduces the dynamic stress in the mechanical elements and therefore, increases the excavator’s operational reliability. The application of the developed control system for the lifting drives of dragline excavators has been substantiated.

NEW SPECIFICATIONS OF THE THEORY OF GROUND CUTTING

Earthwork is performed by some digging machines: excavators, scrapers, graders, dragline excavators, ditching machines, boring installations, etc. Some researchers were engaged in the cutting of soil, and in general, the theory of cutting of soil is rather developed. However, its provisions are correct to the determination of machines of the soil performing almost rectilinear cutting close to a surface, in a dehydrated medium. As practice shows, the known provisions of the theory of cutting do not allow to calculate accuracy the mode and loading of these machines. This article is devoted to the establishment of the regularities determining soil resistance to destruction for construction boring and milling machines. The determined dependencesdetermining the law of change of a corner of a chip when cutting soil as a function from the coupling, pressure in soil, hydrostatic and hydrodynamic pressure upon a surface, the angle of cutting, the angles of internal and external friction are determined. Coefficients of working conditions which describe a high-quality picture of cutting of soil are received and give a ratio of forces in case of rectilinear destruction of soil to forces arising in case of its milling.