2. Technical advantages:

(1) The centrifugal composite casting process is used for producing the roller whose outer layer is made of high nickel chrome molybdenum alloy characterized by high hardness and good wear resistance; and whose core is made of ductile iron characterized by strong strength and high toughness.

(2) The hard alloy layer at the outside of roll is greatly increased in thickness and the service life

of roll is dramatically prolonged.

(3) Unique structure with four rolls of three rolling makes the oil plants to be crushed three times

by four rolls in a machine. The oil plants can be crushed more fully and uniformly; and the productivity is apparently improved.

(4) The fine-tuning part of device is used for eliminating the micro-gap among rolls for crushing

through turbine, screw, and double nut. Meanwhile, the crushing pressure is guaranteed on the

action of butterfly spring; hence, one of the four rolls is fixed and the other three can be

randomly adjusted.

(5) The feeding part is implemented forcibly and uniformly and the production efficiency is

improved.

(6) The multi-level magnetic separation device is used so that the roll is avoided damaging by the

hard impurities in the raw materials.