The screw drum is the working mechanism of the shearer, which should be able to adapt to the geological conditions of coal seam and the requirements of advanced coal mining methods and co-mining technology.It should also have the function of cutting coal, loading coal and opening the work automatically.The advantages of the screw drum are simple and reliable, but the disadvantages are that the coal is too broken, the coal dust is larger, and the cutting energy consumption is higher. 

        1、 the "three diameters" of the drum usually refer to the diameter D of the circle where the blade is located.After the tooth seat is welded to the blade, the maximum diameter of the spiral blade is called blade diameter D.The diameter of the junction between the inner edge of the spiral blade and the hub is called the diameter of the simple hub D.Drum diameter mainly depends on the thickness of coal seam and the number of drum.

        2、 the cutting depth of the drum belongs to the shallow-cutting working mechanism. The cutting depth of the coal wall is less than 1m, which can make full use of the pressure crisp area of the coal seam and reduce the specific energy consumption of coal mining.

        3、In order to ensure that the spiral blade loads coal to the conveyor rather than pushing coal to the coal wall, the spiral direction of the roller blade should be consistent with the drum steering.Standing in the goaf side to see the drum, the right spiral drum should be clockwise rotation, the left spiral drum should be counterclockwise rotation.This relationship must be maintained regardless of the direction of the shearer. 

        4、the number of helix head under the condition of a certain length of helix blade, the number of helix head is small, the helix rising Angle is large, and the coal loading effect is good.However, the blade helix Angle is too large, increasing the amount of circulating coal and dust flying, so the number of helix head should not be too small.Double helix is often used in shearers for medium and thick seam.When the working conditions are stable and the installed power of the shearer is abundant, the three-head spiral drum can be used. 

        5、Drum speed is a relatively important parameter, which has a great influence on the cutting and loading process of the drum.If the rotating speed of the roller is too high, the cutting chips are too thin, which will produce more pulverized coal and dust flying, and the specific energy consumption is higher.At the same time, it will also lead to the increase of circulating coal, bring adverse effects.But high speed can improve the loading capacity of the roller.As a result of the above reasons, the drum speed has shown a trend of low speed, and the lowest speed has reached 22-25r/min. If the drum speed decreases further, its coal loading effect will become worse, and even the drum will be blocked during coal loading.In order to make cutting lower than energy consumption and high productivity, it must be that the traction speed should be high, the drum speed should be low, the tooth dispersion should be small, even if the coal lumpiness is larger.Using checkerboard configuration and large teeth can achieve the requirements of low energy consumption and high productivity. 

       6、the cutter used by the helical drum is usually called the cutter, the majority of the power of the shearer is consumed by it.The cutter is a wearing part that needs to be replaced frequently, which has a certain influence on the cost of a ton of coal.Therefore, improving the quality and working performance of cutting teeth, the correct selection and installation of cutting teeth, for improving the production efficiency of the shearer and reducing the cost of initial production has the most important significance. 

        The basic requirements for cutting teeth are:

        (1) better tightness.The teeth used to cut coal seams containing hard inclusions shall be of high strength.

        (2) the geometry of the cutting teeth should be able to adapt to different coal quality and cutting conditions, and the cutting energy consumption should be lower.

        (3) the assembly and disassembly of cutting teeth should be simple and rapid, and the installation and fixation should be reliable to avoid the loss of cutting teeth.

        (4) the structure of the cutter and its fixing device shall be as simple as possible to facilitate manufacturing and maintenance.    

        Drum shearer used by the teeth, can be basically divided into two categories:

        There are two forms of flat cutting and pick cutting.The flat cutter is installed along the radius of the roller, so it is also called the radial cutter.The installation direction of the handle of pick shape cutter is close to the tangent of the drum, so it is also called tangential cutter.It is suitable for cutting coal with various hardness, including hard coal and viscous coal.The arrangement of the cutter teeth is an important problem in the design of the roller.The basic requirements are: the lump coal produced should be more, the coal dust produced should be less, the energy consumption should be less, cutting resistance and traction resistance should be more balanced role in the roller.If these requirements can be met, the productivity of the shearer can be increased, while the load on the machine is smaller.  

        7、the arrangement of the cutting teeth of the drum on the blade of the spiral drum directly affects the cutting performance of the working mechanism.The best cutting performance should be the minimum energy consumption, the most coal bunches, the least coal dust, the highest production book.At the same time, the roller force uniform, so that the machine runs smoothly.