scholarly journals Loading Performance of a Novel Shearer Drum Applied to Thin Coal Seams

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 358
Author(s):  
Kuidong Gao ◽  
Xiaodi Zhang ◽  
Liqing Sun ◽  
Qingliang Zeng ◽  
Zhihai Liu
Keyword(s):  
Rotational Speed ◽  
Production Efficiency ◽  
Loading Rate ◽  
Positive Impact ◽  
Structural Parameters ◽  
Helix Angle ◽  
Structure Design ◽  
Coal Seams ◽  
Coal Particles ◽  
Relationship Of

The poor loading performance of shearer drums restricts the development and production efficiency of coal in thin coal seams. Changing operation and structural parameters can improve the drum’s loading performance to some extent, but the effect is not obvious. A two-segment differential rotational speed drum (TDRSD) was proposed after analyzing the drum’s influence mechanism on coal particles. To further reveal the drum’s coal loading principle, the velocity, particles distribution, and loading rate were analyzed. The effect of the matching relationship of the rotational speed and helix angle between the front and rear drum are also discussed. The results show that a lower front drum rotational speed had a positive impact on improving the loading performance, and the loading rate first increases and then decreases with the increase in rear drum rotational speed. The optimal loading performance was obtained in the range 60–67.5 rpm. The front drum’s helix angle had no evident effect on loading performance, and the loading rate increase with the increase in the rear drum’s helix angle. The results provide a reference and guidance for operation parameters selection, structure design, and drum optimization.

scholarly journals Numerical simulation on coal loading process of shearer drum based on discrete element method

2021 ◽  
pp. 014459872110135
Author(s):  
Zhen Tian ◽  
Shuangxi Jing ◽  
Lijuan Zhao ◽  
Wei Liu ◽  
Shan Gao
Keyword(s):  
Numerical Simulation ◽  
Discrete Element Method ◽  
Loading Rate ◽  
Low Cost ◽  
Element Model ◽  
Discrete Element ◽  
Helix Angle ◽  
Loading Process ◽  
Coal Particles ◽  
Element Method

The drum is the working mechanism of the coal shearer, and the coal loading performance of the drum is very important for the efficient and safe production of coal mine. In order to study the coal loading performance of the shearer drum, a discrete element model of coupling the drum and coal wall was established by combining the results of the coal property determination and the discrete element method. The movement of coal particles and the mass distribution in different areas were obtained, and the coal particle velocity and coal loading rate were analyzed under the conditions of different helix angles, rotation speeds, traction speeds and cutting depths. The results show that with the increase of helix angle, the coal loading first increases and then decreases; with the increase of cutting depth and traction speed, the coal loading rate decreases; the increase of rotation speed can improve the coal loading performance of drum to a certain extent. The research results show that the discrete element numerical simulation can accurately reflect the coal loading process of the shearer drum, which provides a more convenient, fast and low-cost method for the structural design of shearer drum and the improvement of coal loading performance.

scholarly journals Complex Effects of Drum Hub Forms and Structural Parameters on Coal Loading Performance

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Kuidong Gao ◽  
Xiaodi Zhang ◽  
Liqing Sun ◽  
Qingliang Zeng ◽  
Kao Jiang
Keyword(s):  
Velocity Field ◽  
Loading Rate ◽  
Structural Parameters ◽  
Cone Angle ◽  
Dem Simulation ◽  
Coal Particles ◽  
New Form ◽  
Motion Parameters ◽  
Thin Seam ◽  
Seam Mining

The extremely poor loading performance of a thin coal shearer drum affects the mining efficiency in thin seam mining seriously on account of the restriction by the complicated mining environment and seam thickness. The coal loading performance of the drum is influenced by several complex factors, such as motion parameters and structural parameters, including the structure and form of the hub. The form of the drum hub is cylindrical in general, and in order to study the influence of the hub form on the coal loading rate of the drum, seven drums with different hub forms and structures were designed. The influence of the complexity of hub structures on the coal loading performance was studied by discrete element method (DEM) simulation in this paper. The change curves with the research object of different drums, such as coal loading rate, velocity field distribution, and contact force between fallen coal particles, were obtained. The results showed that the conical hub drum can improve the coal loading performance than the cylindrical hub drum, and the curve-shaped hub drum had a more obvious promotion on the coal loading performance. The coal loading rate increased first and then decreased with the increase of hub cone angle. Compared with the conical hub drum, the curve-shaped hub drum can not only improve the coal loading rate, but also has a larger space containing coal. This study has proposed a drum with a new form hub which could increase the coal loading rate, and the methods and conclusions provide the guidance for drum hub design.

scholarly journals Simulation of the Working Performance of a Shearer Cutting Coal Rock

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Li-juan Zhao ◽  
Hong-mei Liu
Keyword(s):  
Axial Force ◽  
Rotational Speed ◽  
High Efficiency ◽  
Loading Rate ◽  
Element Model ◽  
Cutting Depth ◽  
Rotating Speed ◽  
Coal Particles ◽  
Coal Rock ◽  
Working Performance

Taking the MG2∗55/250-BWD shearer as the research object and considering the influence of the rock on the working performance of the shearer, the shearer-coal-rock coupled discrete element model was established and its dynamic working process has been studied. The single-factor analysis method was used to study the variation law of the cutting depth, traction speed, and the drum’s rotational speed on the three-way force acting on the drum, the coal loading rate, and the trajectory of the coal particles. The simulation showed that the coal loading rate fluctuated during the start-up phase of the shearer, and it was then constant as the time increased. The value of the cutting resistance was the largest, the traction resistance was the second largest, the axial force was the smallest, and the fluctuation coefficient of the axial force was the largest of all of them. The research showed that the coal loading rate of the drum decreased with the increase of the cutting depth, increased with the increase of the rotating speed of the drum, and decreased with the increase of the traction speed. The three-way force of the drum increased with the increase of the traction speed, decreased with the increase of the drum’s rotational speed, and increased with the increase of the cutting depth. According to the analysis of the coal cutting force and the coal loading rate, the drum could achieve high-efficiency cutting if the cutting depth, rotational speed, and traction speed of the dynamic were matched.

scholarly journals Quantitative Evaluation of Top Coal Caving Methods at the Working Face of Extra-Thick Coal Seams Based on the Random Medium Theory

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Shi Jiulin ◽  
Zhang Quntao ◽  
Gao Xiaojin ◽  
Xue Jisheng
Keyword(s):  
Random Media ◽  
Production Efficiency ◽  
Random Medium ◽  
Field Tests ◽  
Coal Seams ◽  
Medium Theory ◽  
Working Face ◽  
Coal Particles ◽  
Geological Conditions ◽  
Coal Rock

Adopting an effective top coal caving method is the key to enhancing coal recovery and reducing gangue content for the fully mechanized top coal caving working face with extra-thick coal seams. In this study, the movement of coal particles generated during top coal caving is considered to follow a normal distribution. Then, the caving body and coal-rock settlement along the working face during the caving process are studied based on both the random media theory and probability theory. Accordingly, the optimal caving interval and caving sequences are determined, and a novel interval symmetrical coal caving method is proposed. The proposed method is systematically verified with results from physical similarity tests, and different caving methods are assessed by field tests. The results show the following: (1) The coal-rock settlement and the caving body demonstrate clear axial symmetrical features along the working face; the size of the caving body increases as the caving height grows and its shape turns progressively from semicircular to semielliptical with a lower foot of the coal-rock settlement. (2) The caving interval is derived using the sum of the radii of the coal-rock settlement curves formed by the two largest caving bodies. (3) The symmetrical caving approach provides a symmetrical space for the subsequent movement of the broken top coal, which enables a uniform development of the caving body. (4) Compared with the traditional sequential coal caving method with the same number of supports, the interval symmetrical caving method results in a 21.7% of coal production increase, 17% caving rate promotion, and a shortened caving time by 23.4%. (5) The interval symmetrical caving method is found to improve the controllability of the caving process at the fully mechanized top coal caving working face. In general, this work presents a theoretical approach to select the optimal caving methods for the fully mechanized caving working face in extra-thick coal seams for an improved production efficiency of the work face. The results of this study can also provide theoretical significance and referencing value for quantitative analyses of the coal caving methods for work faces with similar geological conditions.

Development and production experience of the multilayer curtain-coated linerboard of Ji’an PM No. 3,

TAPPI Journal ◽  
2014 ◽  
Vol 13 (2) ◽  
pp. 17-25
Author(s):  
JUNMING SHU ◽  
ARTHAS YANG ◽  
PEKKA SALMINEN ◽  
HENRI VAITTINEN
Keyword(s):  
Titanium Dioxide ◽  
High Speed ◽  
Food Packaging ◽  
Production Efficiency ◽  
Positive Impact ◽  
Low Cost ◽  
Board Structure ◽  
Flexographic Printing ◽  
Curtain Coating ◽  
Coating Formulations

The Ji’an PM No. 3 is the first linerboard machine in China to use multilayer curtain coating technology. Since successful startup at the end of 2011, further development has been carried out to optimize running conditions, coating formulations, and the base paper to provide a product with satisfactory quality and lower cost to manufacture. The key challenges include designing the base board structure for the desired mechanical strength, designing the surface properties for subsequent coating operations, optimizing the high-speed running of the curtain coater to enhance production efficiency, minimizing the amount of titanium dioxide in the coating color, and balancing the coated board properties to make them suitable for both offset and flexographic printing. The pilot and mill scale results show that curtain coating has a major positive impact on brightness, while smoothness is improved mainly by the blade coating and calendering conditions. Optimization of base board properties and the blade + curtain + blade concept has resulted in the successful use of 100% recycled fiber to produce base board. The optical, mechanical, and printability properties of the final coated board meet market requirements for both offset and flexographic printing. Machine runnability is excellent at the current speed of 1000 m/min, and titanium dioxide has been eliminated in the coating formulations without affecting the coating coverage. A significant improvement in the total cost of coated white liner production has been achieved, compared to the conventional concept of using virgin fiber in the top ply. Future development will focus on combining low cost with further quality improvements to make linerboard suitable for a wider range of end-use applications, including frozen-food packaging and folding boxboard.

scholarly journals A Numerical Investigation into the PAT Hydrodynamic Response to Impeller Rotational Speed Variation

2021 ◽  
Vol 13 (14) ◽  
pp. 7998
Author(s):  
Maxime Binama ◽  
Kan Kan ◽  
Hui-Xiang Chen ◽  
Yuan Zheng ◽  
Daqing Zhou ◽  
...  
Keyword(s):  
Rotational Speed ◽  
Distribution Systems ◽  
Water Distribution ◽  
Production Efficiency ◽  
Operating Conditions ◽  
Energy Regulation ◽  
Speed Increase ◽  
Energy Field ◽  
Long Run ◽  
Study Results

The utilization of pump as turbines (PATs) within water distribution systems for energy regulation and hydroelectricity generation purposes has increasingly attracted the energy field players’ attention. However, its power production efficiency still faces difficulties due to PAT’s lack of flow control ability in such dynamic systems. This has eventually led to the introduction of the so-called “variable operating strategy” or VOS, where the impeller rotational speed may be controlled to satisfy the system-required flow conditions. Taking from these grounds, this study numerically investigates PAT eventual flow structures formation mechanism, especially when subjected to varying impeller rotational speed. CFD-backed numerical simulations were conducted on PAT flow under four operating conditions (1.00 QBEP, 0.82 QBEP, 0.74 QBEP, and 0.55 QBEP), considering five impeller rotational speeds (110 rpm, 130 rpm, 150 rpm, 170 rpm, and 190 rpm). Study results have shown that both PAT’s flow and pressure fields deteriorate with the machine influx decrease, where the impeller rotational speed increase is found to alleviate PAT pressure pulsation levels under high-flow operating conditions, while it worsens them under part-load conditions. This study’s results add value to a thorough understanding of PAT flow dynamics, which, in a long run, contributes to the solution of the so-far existent technical issues.

scholarly journals Impact of Authoritative and Laissez-Faire Leadership on Thriving at Work: The Moderating Role of Conscientiousness

2021 ◽  
Vol 11 (3) ◽  
pp. 667-685
Author(s):  
Zulfiqar Ahmed Iqbal ◽  
Ghulam Abid ◽  
Muhammad Arshad ◽  
Fouzia Ashfaq ◽  
Muhammad Ahsan Athar ◽  
...  
Keyword(s):  
Leadership Style ◽  
Positive Impact ◽  
Work Relationship ◽  
Laissez Faire ◽  
Relationship Of ◽  
The Impact ◽  
The Relationship ◽  
Moderating Role ◽  
Thriving At Work

This study empirically investigates the less discussed catalytic effect of personality in the relationship of leadership style and employee thriving at work. The growth and sustainability of the organization is linked with the association of leadership style and employee thriving at the worplace. The objectives of this study are to explore the impact of authoritative and laissez-faire leadership styles and the moderating role of the personality trait of conscientiousness on thriving in the workplace. A sample of 312 participants was taken from a leading school system with its branches in Lahore and Islamabad, Pakistan. The participants either worked as managers, teachers in headquarters, or school campuses, respectively. The regression results of the study show that authoritative leadership and conscientiousness have a significantly positive impact on thriving at work. Furthermore, conscientiousness moderates the relationship between laissez-faire style of leadership and thriving at work relationship. The findings of this study have theoretical implications for authoritative and laissez-faire leadership, employee conscientiousness, and managerial applications for the practitioners.

Dynamic Characteristics Analysis of Cable-Rib Tension Deployable Antenna

2016 ◽  
Author(s):  
Liu Ruiwei ◽  
Hongwei Guo ◽  
Zhang Qinghua ◽  
Rongqiang Liu ◽  
Tang Dewei
Keyword(s):  
Dynamic Characteristics ◽  
Structural Parameters ◽  
Element Model ◽  
Structure Design ◽  
Antenna Structure ◽  
Characteristics Analysis ◽  
New Type ◽  
Dynamic Characteristics Analysis ◽  
The Finite Element Model ◽  
Weight Dynamic

Balancing stiffness and weight is of substantial importance for antenna structure design. Conventional fold-rib antennas need sufficient weight to meet stiffness requirements. To address this issue, this paper proposes a new type of cable-rib tension deployable antenna that consists of six radial rib deployment mechanisms, numerous tensioned cables, and a mesh reflective surface. The primary innovation of this study is the application of numerous tensioned cables instead of metal materials to enhance the stiffness of the entire antenna while ensuring relatively less weight. Dynamic characteristics were analyzed to optimize the weight and stiffness of the antenna with the finite element model by subspace method. The first six orders of natural frequencies and corresponding vibration modes of the antenna structure are obtained. In addition, the effects of structural parameters on natural frequency are studied, and a method to improve the rigidity of the deployable antenna structure is proposed.

The Design and Implementation of a Handling-Robot

2014 ◽  
Vol 644-650 ◽  
pp. 290-293
Author(s):  
Zhi Hui Deng ◽  
Yun Hang Zhu
Keyword(s):  
Production Efficiency ◽  
Structure Design ◽  
Stepper Motor ◽  
Current Sensor ◽  
Single Chip ◽  
Single Chip Microcomputer ◽  
Accident Rate ◽  
Repetitive Work ◽  
Design And Implementation ◽  
Information Interaction

A robot based on STC12C5A60S2 single-chip-microcomputer is designed for improving the production efficiency and reducing repetitive work. The system could identify path by detecting metal using eddy current sensor. By ways of the single-chip-microcomputer controlling stepper motor, the robot can run according to the predetermined route, judge independently cargo range and deliver the goods to the designated location. The implementation methods of the important links, such as mechanical structure design, path recognition and steering engine driving and so on are introduced, the system of which make the information interaction with computer through ISP-module (In-system-programming).by testing the model, it shows that the system can meet the design goals of handling goods automatically, and it has higher application value of reducing the accident rate of worker in repeated works and improving labor productivity.

FEM Comparative Analysis of Synchronous Rotor with Different Helix Angle in the Process of Mixing

2012 ◽  
Vol 501 ◽  
pp. 388-392
Author(s):  
Hui Guang Bian ◽  
Wei Shuai Lv ◽  
Chuan Sheng Wang
Keyword(s):  
Comparative Analysis ◽  
Theoretical Basis ◽  
Production Efficiency ◽  
Transient Flow ◽  
Flow Simulation ◽  
Helix Angle ◽  
Original Performance ◽  
Mixing Performance ◽  
Axial Tensile ◽  
Flow Mixing

The paper is used to analyze the structure of traditional synchronous rotor from the perspective which the helix angle between long edge and short edge has some difference. The specialized viscoelastic fluid software--Polyflow is used to dynamic simulation analyze the two different kinds of rotors during the process of flow mixing, and then to analyze the two kinds of rotor performance through the result of transient flow simulation which mixed for one second. The analysis revealed that the improved synchronous rotor had better axial tensile properties in the case of remaining the original performance basically unchanged. And that could improve mixing performance and the production efficiency of mixer more effectively. There will provide a theoretical basis for the optimization of the rotor configuration in future.

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