Failure of underwater granulator and improvement measures
Cause of gu barrier
Influence of fixed knife
The originally fixed knife is made of integral Crl2MoV material, the deviation of straightness is less than 0.01 mm, and the cross-sectional size is 20 mm×8 mm.
Its wear rate is much faster than the movable knife because the movable knife has 30 teeth. In other words, the fixed knife wears 30 times, while the movable knife wears once.
When the cutting edge of the fixed knife is worn to a certain extent, the cut pellets will have burrs, which will affect the appearance quality of the cut pellets, so it is necessary to change the blade and sharpen it. Under the output of 120 t/d, it can only be maintained for 5-7 days.
Another situation. With the multiple grinding of the movable knife, its outer diameter has been greatly reduced, resulting in a space between the fixed knife holder and the scraper.
Clipping, random cutting, and a lot of irregularities in the cutting, especially when switching. The problem is more serious the gap change is shown in Figure 1.
Image 1 (Moving knife external diameter clearance pre and post reduetion)
The effect of the back angle
The back angle of the moving knife is to reduce the friction between the blade surface and the slice.
At the moment of cutting off, the cast belt continues to decline. Before the future of the subsequent teeth, the cast belt will rub against the back.
The result of friction leads to the irregular movement of the casting strip, and the casting strip arches to form disorderly cutting (forming irregular fragments). Therefore, the bigger the rear angle, the better, but the strength of the knife decreases accordingly.
Quote-[1] Fang Cheng, Dong Zijun. Troubles and improvement measures of underwater pelletizer [J]. Polyester Industry, 2005, 018(006): 41-43
