Failure of underwater granulator and improvement measures（2）
The influence of lead gap
The pelletizer feed roller is in the lead. The cast strip mainly relies on the friction between the guide rollers to “bite”, and the gap is generally controlled at 1.25-2.0 mm.
When the casting bar is in contact with the rotating guide roller, the force of the guide roller on the casting strip includes positive pressure and friction.
The friction and positive pressure are given to the casting strip by the front and rear guide rollers are not enough to resist the vertical component of the cutting force.
That is, the positive pressure is given to the casting belt by the front and rear rollers are not enough. At this time, the casting belt is pulled, that is, the casting belt slides between the two guide rollers, and the proportional relationship between the designed feeding speed and the cutting speed is destroyed.
There will be uneven slices. Therefore, cut out qualified slices. It must be required that the lead roller has sufficient positive pressure on the casting.
In addition, when the rear lead roller is excessively worn, due to the uneven gap along the length of the roller (local wear), the cast strip in the recessed part cannot be fed, resulting in an unbalanced rotation torque and downward pull force generated during shearing. Produce random cuts.
The frictional resistance generated by it can overcome the downward force generated during cutting. This positive pressure is generated by the inherent factor that depends on the casting belt to have a sufficient depth of depression between the two lead rollers, and the external factor is dependent on the pressing force provided by the two cylinders (pinch cylinder) to the front lead roller.
Therefore, the lead gap must be less than the difference between the thickness of the cast strip and the pressing depth to cut pellets normally, otherwise, the cutting strip will tremble and cut out similar to the jaw-like slices.
The actual situation is that when the leadership gap is too large, the casting bar will dance like a silver snake. The cut-out products are of different sizes and are accompanied by a large number of long strips, which cannot be cut into pellets.
Quote-[1] Fang Cheng, Dong Zijun. Troubles and improvement measures of underwater pelletizer [J]. Polyester Industry, 2005, 018(006): 41-43
