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Analysis of rolling system problems in China

1. At present, most domestic roller presses adopt the control mode of low pressure and large circulation, the pressure is low, the average roller pressure is 60-80Mpa, the peak pressure is also 120-150Mpa, the proportion of fine powder produced is small, and the fineness is 0.08mm. In 70-80%, 0.9mm or more accounted for about 50%, the extrusion effect is poor; the roller motor running current fluctuates greatly, the running current is about 50% of the rated current, and the actual operating power is lower.

2, the roll gap control has two ways, one is constant pressure control, one is constant roll gap control; its motor running current fluctuates greatly, PLC control mostly adopts German Siemens, running roll gap and pressure fluctuation is large Plus, the back roller press has a lot of fine powder, sometimes it will produce strong resonance.

3, iron remover, hard object cleaning system is poor, the system has iron removal, but can not ensure that no iron, hard objects, especially stainless steel, high-chromium steel balls and other hard objects; due to roller press material circulation, enter Hard objects and iron blocks cannot be excluded.

4. At present, most of the roller press feeding devices feed the material directly into the roll gap after passing through the silo, and pull the material between the two rolls, that is, the so-called pull-in angle of the roll press for extrusion; flow adjustment The range is limited and it is difficult to accurately and stably control; at the same time, the silo has the position of the warehouse, and the material segregation phenomenon sometimes causes the roller press to vibrate greatly; the improved feeding device can control the opening degree, but the effect is not good and fails to be effective. Control traffic.

5. At present, the roller speed of domestic roller presses is generally 1.5-1.7 m / s, the line speed is too fast, which is easy to cause the roller press to vibrate; plus the low pressure large cycle, the material flow is large, the roll gap fluctuates greatly, and it is used. The motor power is too small, resulting in large fluctuations in motor operating current and poor operational stability.

6. The roller press is equipped with a dispersing machine in the early stage and V-selecting in the later stage. Due to the low efficiency and fast wear of the dispersing machine, the grading control is difficult, and there are many problems in use, but the effect is not great; V-selection cycle The load is too large and the wear is fast. Although the fine powder particle size is controlled, the coarse powder contains a large amount of fine powder, so that the roller press works poorly.

7. In the design of the combined grinding system, the ingredients are stable and controllable. The feeding of the roller press will cause segregation and unstable flow, while the material to be milled will be stable by the operation of the roller press system and cannot be displayed. The flow rate is adjusted by the fineness index and experience, and the actual operation is difficult. The traditional double-layer compartment board is difficult to adapt to the current requirements. The partition board is blocked, the stroke is too large, the side wind is too small, and the material flow rate cannot be controlled. The grinding and grinding phenomenon in the grinding is serious.

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