Rolling Mill Bearing Failiure Analysis

Years of analysis statistics of the failures of the rolling mill bearings in CHG indicate that more than 30% of the failures are caused by inappropriate installation.

Pay attention to the concentricity on the surface between the bearing and the roll neck and housing hole when the bearing is installed to avoid load deviation when the bearing is used. To eliminate deviation when the bearing is manufactured the inner ring of the Four-row Cylindrical Roller Bearing currently adopts the modus operandi of installing the inner ring of the bearing into the roll neck in advance for integrated grind which is simple and practical.

The clearance inside the bearing after the bearing is grinded must be matched with using temperature and temperature rise. For example the axis of the inner ring and the outer ring of the bearings on the two fulcrums of the roll will deviate because the housing hole of the bearings are not in the same circle center, or the side surface of the shaft shoulder is not vertical to axis, or the housing hole on one end tilts, or the axis is deformed after the roll is loaded etc..

It is required that the bearing has certain spherical performance which is the ability of working normally when relative deviation occurs on the axis of the inner ring and the outer ring. Under this condition CHG changes the inside designing parameter which makes the 370000 type Two-row Tapered Roller Bearing has the ability of slight adjustment to adapt to this condition. But on the rolling mill with four rollers the support roller generally adopts multiple-row bearing (the rows on the bearings are generally assembled in pairs).

Because when the Four-row Tapered Roller Bearing, Four-row Cylindrical Roller Bearing and Double-row Tapered Roller Bearing are used as a combination the bearing itself does not have the performance of self-aligning and the roller works under a large bend load. In fact the housing of the bottom roll is placed inside the even support base surface. Under this condition the bearing cannot adjust itself to compensate the non-concentricity on the bole hole of the bearing’s housing and the flexure on the axis after the roller is loaded. This intensifies the nonuniformity of the force on all rows of rolling element thus the lifespan of the bearing is lowered sharply. To solve this problem the self-aligning performance problem of the housing should be solved. And the housing should have the ability of changing along with the changing of the load of the roller. The housing should have the self-aligning feature. Please contact CHG if consultancy is required.