Double toothed roller crusher is used for the crushing of medium hardness materials, such as coking coal, sinter, limestone, metal and non-metallic ore. It is especially suitable for the fine and medium crushing of non-metallic ore in small and medium-sized mine. The minimum granularity is smaller than 100 mesh. This crusher has simple structure, is easy for operation, and can achieve ideal crushing granularity as well as stable performance through adjusting the clearance of crushing roller. But the crown of roller crusher is easy to be broken, the reasons are as follows:

1. The crown receives the large impacting force from the falling lump ore leading the back crown breaking;

2. If there are too many lump ore, the crown is easy to be damaged or broken;

3. The extension of crown bolt leads to the fracture of the crown.

Solution: Adding steel plates at both side of the crown on the crusher to make it into a box crown, which can make the crown live for more than two years.