Main Problems of the mineral sizers at Present are the transmission type is backward and the open long tooth gear is adopted to ensure that the transmission of the movable tooth roller will not be interrupted when it retreats. The meshing clearance of the gear is very large, and there is a serious impact during operation, and the no-load noise reaches 90103db. Limited by the transmission system, the toothed roller can only work at low speed. To improve the processing capacity, the only way is to increase the size of the toothed roller, which makes the whole machine bulky and bulky. The first-class gear transmission and the big ken wheel at the shaft end of the toothed roller used in the existing mineral sizers in China are located on both sides of the frame, which belong to open transmission and have poor lubrication conditions. The gear teeth of large gears are "special long teeth", which are difficult to machine with low precision, and the backlash during meshing is very large. Although the rotating speed of the gear roller is very low, generally not exceeding 50r/min, there is a big impact when it is running, and the noise at no-load is over 87B. The low transmission efficiency limits the improvement of productivity.
The material of the short-life broken toothed plate is ZGM13, which is worn seriously in use, and the phenomenon of broken teeth occurs from time to time. The service life is generally 35 months, and the toothed roller bearings are sliding bearings or tapered roller bearings, which have poor bearing capacity and are easy to wear. The annual maintenance cost of the equipment is up to 230,000 yuan/set.

The energy consumption per ton of coal is 0.37KW, and the phenomenon of product granulation and over-crushing is serious.
Inconvenient maintenance: the equipment has incomplete functions, and the user can't adjust the center distance of the toothed roller at any time, so it's inconvenient to use and maintain. Thus,it can be seen that the old toothed roller crusher has a small backward processing capacity and can't meet the needs of modern large mines. The existing spring buffer devices of some mineral sizers in China only have one function, that is, when the hard-to-break materials enter the crushing box, the spring is further compressed, and the distance between the toothed rollers can be increased by moving the toothed rollers to give way. After the hard-to-break materials pass through the crushing cavity, the toothed rollers are moved back to their original positions under the action of the spring force. Because the structure of the device is not perfect, it brings a lot of inconvenience to the field use, the discharging granularity is not up to the requirements, and the center distance between the toothed rollers can't be adjusted. Especially in case of unexpected power failure or sudden shutdown of the safety pin, the materials accumulated in the crushing box can only be removed manually, which is laborious and time-consuming.

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