Application of hydraulic special tools in equipment maintenance

Abstract: Today hydraulically powered production in all sectors of special tools widely used in the coal mine. Hydraulic special tools have also been increasingly applied to hydraulic power in the coal mine equipment maintenance work has an important position. Special tools that are powered by hydraulic systems can solve the problem that equipment and spare parts cannot be dismantled in the actual maintenance process. And can be effectively applied to work by maintenance personnel.

Keywords: hydraulics; special tools; actual maintenance: dismantling: effective application

0 Introduction

Zhangji Coal Mine is located in Fengtai County, Huainan City, Anhui Province. The mine now has a certified production capacity of 12.4 million t / a , which is the largest production mine in Huainan Mining Group. It is also the first million-ton-class modern large-scale mine in Anhui Province. With the further modernization of fully mechanized coal mining equipment, the specifications and models of coal mining machines, transport aircraft, and hydraulic supports are becoming larger and larger. It is also more difficult to dismantle equipment and spare parts during the maintenance of large-scale equipment. After equipment is used underground for a period of time, The large amount of water in the well and the heavy humidity cause the corrosion of the components to be very serious. Relying on manpower alone, the equipment to be repaired cannot be dismantled with sledgehammers, pull hammers, etc. Currently, special tools for hydraulic power generation in various departments of coal mines are widely used. Although there are also electrical, pneumatic or mechanical systems available, the use of hydraulic special tools has become more and more popular due to the versatility, efficiency and simplicity of hydraulic systems in power transmission. The task of hydraulic systems is to transform power from one form to another. Hydraulically-powered special tools have increasingly demonstrated their importance in the maintenance work of coal mines. The application of hydraulic special tools in the maintenance of coal mine equipment is described with examples of the two encountered in the work.

1 limiter removal device

Fully-mechanized face of Zhangji Coal Mine usually adopts SGZIO00 / 1400 type scraper conveyor and Jiuyi 7LS6 , Ekoff SL750 shearer, ZZ9200 / 24 / 50 hydraulic support, SZZ1000 / 400 type loader and PCM250 hammer Crusher, SSJ1200 belt conveyor and other supporting use to achieve a comprehensive mechanized coal mining face. During the downhole operation, the entire reducer was replaced due to oil leakage from the input shaft of the SGZ1000 / 1400 transport reducer. The reason is that the input shaft seals of the transport reducer are seriously worn out. This problem can be completely resolved in the production unit downhole, only need to replace the seals. However, friction torque limiter is installed between the reducer and the motor. Friction torque limiter cannot be removed. And had to replace the overall reducer from the time of shipment to the replacement of at least 3 small classes. Time-consuming. There are also great safety risks in the processes of transportation and lifting, which have a great impact on production.

Friction torque limiter is used in underground coal mine scraper conveyor. Its main function is to prevent damage to chain, sprocket and reducer, etc. due to overload impact. Zhangji Mine's XJQ - 700 friction torque limiter set torque close to 700 kW 4 times the rated torque of the motor . When the safe operation of the entire scraper conveyor system plays a protective role in the factory, the factory is also provided a special removal tool, including the "gland", "screw", "rod" three parts. The method of use is to fasten the "gland cover" through bolts and friction limiters. Then pass the rod through the hole on the end of the screw. Screw the "screw" into the threaded hole in the center of the gland. And with the reducer of a shaft end tight. Apply high torque through the "spindle". The friction limiter is removed from the shaft of the reducer but is actually used in the downhole field. This kind of design is ideal for tools only for new reducers. The new friction torque limiter has a demolition effect device and the friction reducer and the friction torque limiter are used in the downhole because of the damp environment. Severe corrosion. The special tool can not disassemble the frictional torque limiter and the disassembly of the friction torque limiter is operated manually, and the disassembly efficiency is low. And when disassembling, the artificially provided power is usually insufficient to disengage the friction torque limiter from the input shaft of the speed reducer and cannot be disassembled.

Against the above problems. The special tool design for dismantling frictional torque limiters must meet the following conditions:

1 can be used downhole, first is the power section. If you choose electricity as a power source. Special underground anti-explosive motors are also considered to use the emulsifying pump downhole. Can provide a good source of power;

2 must have enough motivation. Ordinary hydraulic jacks can reach rated pressure when used vertically. But dismantling the torque limiter should be used sideways. Ordinary hydraulic jacks cannot meet the requirements when used transversely and cannot reach the pressure. Finally, select the hydraulic jack for the bracket:

â‘¢ Downhole Face spacing is small space, manpower can be detached by lifting jack type movable ZZ6400 / 18/38 to help protect the bracket rated working pressure of the jack 31. At 5 MPa , the tensile force is 126 kN . Travel 470 mill , dimensions 980 to 1 450 mm , weight 49 . 47 kg . Thousands of base adjustments at rated working pressure 31 . 5 MPa . Pull 207 . 8 kN , stroke 150 mm , dimensions 580 to 730 mm , weight 47 . 03 kg , choose the base jack for the demolition jack; 4 must have sufficient strength. Chuck and support plate are made of steel plate thickness = 30 mill or more. Rods are made of round steel with a diameter of 4,30 or more. Two processing M30 threads for mounting nuts. Fixed lever. As shown in Figure 1 .

Figure 1 Dedicated tool for dismantling frictional torque limiter

1. Power plant 2. Support plate 3. Pull rod 4. The torque limiter to be dismantled 5. Through hole 6. Input shaft 7. Chuck 8. Telescopic power arm

How it works: The chuck chucks the friction-reducer-reducer side and uses a nut to adjust the support plate to the correct position. The piston end of the hydraulic jack withstands the center position of the input shaft of the reducer (the diameter of the piston rod is smaller than the diameter of the shaft ) . The rear end of the hydraulic jack is connected to the support plate. Emulsion liquid supply. Hydraulic jack piston rod out under the action of pressure fluid. When the hydraulic jack and the reducer input shaft and the support plate are tight. Because the reducer is fixed, the rear end of the hydraulic jack acts against the supporting direction of the hydraulic jack. The support plate drives 6 rods. The pull rod drives the chuck to move in the same direction. When the force is greater than the friction force of the friction torque limiter and the input shaft, the friction torque limiter will be separated from the input shaft of the speed reducer under the drag of the chuck.

2 hydraulic bracket disassembly device

Zhangji Mine's 1132(3) working face is high due to high mining height. In order to make better use of resources. Use ZZ9200 / 24 / 50 type bracket. The set of hydraulic support is in accordance with the geological conditions and requirements given by Zhangji Mine of Huainan Mining Group Corporation. According MT312 - 2000 <General "hydraulic support in the design. Meet the national coal equipment safety regulations. The bracket type is large, the width, height and weight exceed the single-tank lifting capacity of the mine. After the study decided to disassemble the bracket into three blocks: the top beam, the cover beam, and the base to facilitate the entry into the well. The top beam is in the form of a hinged front beam. The front beam has a telescopic beam with a secondary guard jack. The top beam has thrust jacks inside. It is composed of side guards. Covering beam with double active side guards. When using one side fixed. Side activities. The front end of the cover beam and the top beam are articulated, and the rear end is hinged with a four-bar linkage. And through the four-bar linkage and the base constitute an indispensable four-bar linkage in the hydraulic support. This mechanism makes the hydraulic support in the up and down movement. The trajectory of the center point of the hinge between the cover beam and the top beam forms a nearly straight twisted wire. In order to meet the hydraulic support has a reasonable and stable movement mechanism. The cover beam is a box-shaped structure and its interior is equipped with side protection jacks and other components. The base is a front end opening and a rear half closure structure. The front and rear bridges are connected. The front end is equipped with a lifting mechanism and the bottomed jack jack base is in direct contact with the bottom plate, and it withstands the top plate passed over by the top and bottom columns. Vertical pressure also withstands the upward force exerted by the soleplate. And the four-bar linkage to pull pressure, distortion force. Removing the ZZ9200 / 24 / 50 bracket has also become a very difficult thing. The pin diameter of the four-bar linkage mechanism is +140 mm . Demolition is very difficult with the manufacturer's proposed hammer method, 3 workers work in rotation. 30 to 40 minutes to pull down a pin. 1 set holder 6 together with large pin row line, a small pin, a holder station 1 D only be removed. 1132(3) Working face duration is particularly demanding. Each day must ensure that the removal of 8 10 brackets to ensure the smooth installation of the work surface.

The manpower method of the original pull hammer can not meet the needs of the existing production, but the principle can be used. The working principle is shown in Figure 2 . Pull the pin out in the direction of the human f .

Figure 2 working principle of the pull hammer

1. Pull hammer 2. Pin shaft

As shown in Figure 3 . Ll to a frame beam welding, the welding tip cap 3 = steel plate of 20 mm. A +260 mm hole is opened in the middle to allow the pin to pass through the frame to weld the bottom holder for the telescopic jack tail. Because of the live connection with the jack. Jacks have problems for easy replacement. The side of the frame welded flat iron is also used to fix the jack. Maintain the overall structure of the center of gravity smooth telescopic jack stroke of up to 900 mm , fully meet the working distance of the end of the welded frame steel plate. To ensure that the pin exit from the structure is convenient. Special joints also have M22 , M24 , M42 and other specifications, to meet the use of large-axis and small-pin shafts.

Figure 3 Fixing device

1.11 I-beam 2. Flat iron 3. Curved steel plate 4. End cover 5. Pin 6. Special connector 7. Telescopic jack 8. Bottom holder

Bracket hydraulic removal tool put into use. Greatly improve work efficiency, before the original hydraulic bracket disassembly work. The hydraulic support must be fixed mechanically. For example, insert a wooden wedge between each pair of four links. Use a chain or other effective method to secure the replacement parts on the inclined face. In order to prevent the roof beam, cover beam suddenly drop and suddenly replace the replacement parts. When manually dismantling 3 people 1 pin axis 30 ~ 40 min . And there are disassembling security risks. Use of hydraulic support removal tools, on-site security risks greatly reduced. Two small classes can complete the work of disassembling 8 to 10 stands. The tool is simple to manufacture, easy to use, and economically beneficial.

3 Conclusion

It needs to be seen through the above two examples. Hydraulically powered special tools have great promotion space in the daily maintenance operations of coal mines. The use of hydraulic power sources will greatly reduce the labor force and increase production efficiency. Equipment and parts that cannot be dismantled by manpower can also be easily dismantled after using hydraulic special tools. At the same time, work efficiency has been greatly improved. As long as there are conditions in the work site as far as possible to use hydraulic power as a hydraulic tool to complete the demolition of equipment. The economic benefits are considerable.

The information in this paper comes from Coal Mine Machinery, Volume 35, Number 11, November 2014.