英语从零开始学习英语攻略37期

英语从零开始学习英语攻略37期 Xin Pu is 3.8?, "several problems should be noticed in graduation thesis defense This article is 7350 words, divided into 5 pages, the page first, page 12345: fast The matching and selection of fully mechanized coal mining equipment is directly related to the working face of fully mechanized mining equipment, the realization of the goal of the annual output of the working face. The author briefly introduces the supporting type selection of fully mechanized coal mining equipment in the intelligent working face. 1 type selection of hydraulic support The practice shows that the initial pressure strength of the basic roof of large mining height increases with the increase of mining height. The basic roof period, the pressure step length increases with the increase of mining height, and the period of the compression strength increases, but it is generally less than the initial compressive strength. Therefore, the large mining height support should have a high support strength and work resistance, should be able to withstand the impact load of the roof. On the other hand, with the increase of mining height, coal wall spalling intensifies, the increase of pressure, and easily lead to collapse. Therefore, the large mining height support should be improved in the protection of the device and the advance support device, the top should have a larger support. Support should be in accordance with the requirements of surrounding rock, to meet the requirements of supporting and production. Past mining experts generally agree that cover bracket type of instability and medium stable roof adaptability is good, cover type of support beam at the front end of the supporting force and roof cutting ability is poor, support shield support is applicable to the stability of roof and hard roof frame cut top performance. Therefore, the branch support shield type support for in the roof to pressure intensity, immediate roof stability of working face. Along with the deepening research on the interaction between support and support and the surrounding rock of fully mechanized coal mining face, the understanding of the frame type is continuously deepened. New research shows that four support due to the four column at the same time can not be affected by the force and actual use tend to occur before and after column stress uneven phenomenon, four post bracket support efficiency less than the actual cover scaffolding support efficiency. In addition, large bore column and provided the base mechanism used greatly expanded the scope of application of shield support, thus changing the people of shield support understanding of the past. At present, has become a two pillar shield hydraulic support the development direction, main coal producing countries in the United States, Australia, Germany and South Africa have all been used two pillar shield support, our country some new large modern mine is generally used by shield support, in different conditions using success. Because of the stability of the two pillar shield type support, the application scope of the shield support is enlarged in the large mining height mining. And due to the mining height, the stability of the stent has become an urgent need to solve the problem, so now the large mining height two pillar shield support to the direction of the development of the center. The 1.75 m, 2.0 m center distance, not only can greatly improve the support stability, and can reduce the number of stents, simplify the electro-hydraulic control system, reduce equipment investment costs, and improve the move speed of support and overall equipment reliability. On the other hand, to improve the working resistance of hydraulic support is also the development direction of large mining height hydraulic support. Higher hydraulic support at the beginning of the supporting force and resistance can reduce the roof of coal wall in the front abutment pressure, so as to avoid the coal wall broken, is conducive to the prevention of working face film help, roof and lead to a variety of mine pressure behavior law, is the large mining height working face can be guaranteed to achieve high yield, high efficiency and high security. According to the Tunlan coal mine roof conditions, consider successful experiences and developing direction of the high-yield and high-efficiency coal mines at home and abroad, equipped with large flow control system and electric hydraulic control system, to achieve fast moving frame, use two columns cover stent is more favorable, so the scheme intends to choose two column shield hydraulic support. Hydraulic support the basic selection principle should enable support support support strength and fully mechanized mining working face coal seam geological conditions and coal seam roof mine pressure behavior strength of fit, also support base on the floor than the pressure to adapt to the compressive strength of coal seam floor. According to the above principles and conditions, I choose the ZY8000/2.5/5.0 type of hydraulic support. ZY8000/2.5/5.0 shield type hydraulic pressure support has the following characteristics: one is the support absorbs the domestic and foreign cover type hydraulic support has the advantages with high adaptability, high reliability, compact structure, large supporting capacity, convenient operation, shift and fast frame rate characteristics. Two is the bracket using the parameter optimization design, through the dynamic interference check, the movement simulation simulation, has the high mechanical property. Three is the stent designed to meet the 312/000 MT standard. The four is the supporting ability, two 320 mm diameter bore column, the working resistance reached 8000 kN. Five is the use of the whole beam, simple structure, good reliability, in order to improve the effect of the top, the front end of the top beam up 50 mm. Before and after the beam is about 2.8. Six is the use of a form of protection, the first level of care to help the board through the four link mechanism and the first level of protection to help jack connected, not only can help, but also can flip the temporary support of the roof. Seven is the double front and rear connecting rod, the rear link for the overall structure, improve the stability of the support frame and stability. Eight is the selection of a single bore diameter balance Jack 200 mm, increasing the balance torque, enhance the ability to adapt to support. Nine is the passage mechanism for long push rod box structure, push jack upside down, reliable structure, good adaptability, moving frame force, can realize fast moving frame. Ten is the base of the bridge behind the lifting of the base device. The device is simple and reliable in structure, convenient loading and unloading, the front end of the base raised 100 mm to 150 mm, moving frame, operation bottom lifting jack to lift the front end of the base, to support forward to improve the frame shift speed. Eleven is a bracket base for the bottom of the rigid base, the front of the base with the bridge connection, the back of the box structure is connected, the base plate is divided into two parts, the middle part is free, is conducive to the floating coal discharge and lift the base. Twelve is a bracket with a dual pedestrian channel, is conducive to safe production. The thirteen is equipped with a beam, a shield beam with side guard plate bracket, good sealing performance, strong adaptability. Fourteen is the support hydraulic system using PM31 type electro hydraulic control system. 2 type selection of Shearer 2.1 selection principle The production capacity of fully mechanized coal mining face is mainly determined by the coal cutting ability, which is related to the maximum cutting speed of coal mining machine, the time of non fault cutting coal, the maximum depth of cut, the maximum mining height and the capacity of coal. The time of cutting coal without the help of cutting coal depends on the reliability of fully mechanized coal mining equipment, the occurrence condition of coal seam, the mining technology and operation mode. And the reliability of the equipment is largely determined by the power and mechanical properties of the machine. So the shearer selection according to the coal seam conditions and parameters of working face, the production capacity can reach full mechanized mining face design with an annual output of 300 million T, and satisfy the matched with the scraper conveyor, hydraulic support. When the mining height and the depth of cut are certain, the production capacity of the working surface is determined by the traction speed or the power of the coal mining machine. Therefore, the choice of shearer, according to the mining height, cutting depth, traction speed and power selection, also shearer should can satisfy and realize the requirements of the working face ends beveling feeding from the open gap, give high priority to the use of electrical haulage shearer. 2.2 type selection and characteristics Selection of 2.2.1 shearer drum According to the working face mining height of 4.7 m, as well as to consider the future to be about 5 m or so coal seam, large mining high coal seam requires the choice of double roller, can be two-way coal mining, but also can open the gap. Drum diameter is generally 0.55 to 0.6 times the height of the mining height, the diameter of the drum is mm = 2500 D, which can meet the normal production of the working surface. Selection of traction speed of 2.2.2 Shearer According to the geological conditions of coal seam and production technology, and increase the reliability of equipment, as well as the preparation of a certain degree of prosperity, the selection of shearer traction speed. According to the calculation, the working face length not less than 150 m, to achieve a predetermined volume, to ensure that the operating rate of the 40% ~ 50%, shearer traction rate of not less than 4 m to 6 m / min, selects the shearer traction speed should be 9 m / min to 12 m / min. The development trend of coal mining machine is to electric traction gradually replacing the hydraulic traction, to multi motor, high power, electromechanical integration direction development, both to improve the cutting and traction speed and the cutting depth, greatly increasing the yield per unit area, and increase the operation reliability and easy to operate, safe and convenient maintenance. According to the above principles tentatively recommends MG500/1200 - 3.3D type AC variable frequency electric haulage shearer, its main parameters: total power 1 200 kW, drum diameter 200 mm, range of mining height 2.2 m ~ 4.5 m to 16 degrees angle is less than or equal to, cut 400 mm in depth, cutting depth of 800 mm, cutting power motor 2 x 500 kW, traction motor 2 x 55 kW, 20 kW pump motor, traction speed of 750 m / min to 50 m / min, the power supply voltage 3 300 V. Selection of 3 working face scraper conveyor Select the main principles of the scraper conveyor is the maximum production capacity of fully mechanized mining face as the base to ensure the reliability and durability of fully mechanized mining face transport capacity and transport equipment, taking into account the equipment startup, protection and control performance. Mainly in the following aspects: First, the conveyor capacity and the maximum production capacity of coal mining to adapt, and there is a certain reserve capacity. In the same situation of transport capacity, select a small width of the model. Second is combined with coal hardness, size, volume selection structure (single and double chain, double chain, etc.), the coal is hard, block large preferred bilateral chain; soft coal may use single - or double center chain. Three is the choice of welding structure of conveyor chute with high strength chute, generally preferred sealing type. The back cover type resistance, mainly used for soft bottom conditions. Lan mine is a mine of Shanxi coking coal Xishan coal mine, the original design annual production capacity of 4 million T. Though Tunlan coal mine is rich in coal resources, coal quality, but also by various natural disasters, the serious threat: one is mine gas emission quantity, which belongs to the high gas mine; the second is mine hydrogeological condition is very complicated, the recoverable coal seam region mining with pressure, maximum pressure reached 5.57 MPa, was a potential threat to the mine safety production; three is broken roof, Tunlan coal mine roof for ternary composite roof. In order to build an efficient and safe mine, and further enhance the market competitiveness, the construction of the 12209 intelligent chemical industry, so that the coal production of the coal mine has exceeded 5 million T. 12209 working face ground elevation 1 085 m ~ 1 218 m, working face coal seam floor elevation 695 m ~ 730 m, working face main mining of No.2 coal seam, stability of coal seam thickness, thick about 4.3 m, the overall trend of monoclinal structure, toward to the southeast, dip 1 DEG to 8 DEG, roof: pseudo top 0.5 m, black mudstone and compressive strength difference, immediate roof M 0 to 2.5 m, grey fine sandstone, texture is hard, old top 5.7 m, siltstone, gray fine sandstone, siliceous cementation and bottom is 5.3 m, deep grey siltstone and fine sandstone. The design length of working face is 159 m, mining height is 4.7 m, depth of cut