Ridgeback^TM Liner Bolt

The RidgeBack's™ new bolt head increases contact surface by conforming to the shape of the tapered surface of the liner hole. In conventional liners, the oval radius of the bolt is about 15% less than the oval radius of the liner. These differing geometries lead to only a line contact on either side of the head. Furthermore, any difference between the taper angles of the bolt and liner will reduce the contact area from a line to a point. Small contact area leads to high local stresses which plastically deform when the mill is put in-service. This plastic deformation causes premature loosening and makes frequent retorquing necessary. As the RidgeBack™ is tightened, projecting ridges plastically deform during assembly (not afterwards!) to take the individual shape of the tapered liner seat. By establishing a greater contact surface during assembly, the bolts will maintain preload longer and can eliminate the need for retorquing.

The Ridgeback^TM bolt was designed by our engineers especially to solve bolting problems that users were encountering when liners were installed.  There is a 1/8" all-around clearance between the bolt and the liner; therefore, when the bolt is installed, it rests on two points and is not stable.  To stabilize the bolt, our engineer designed ridges along the taper of the bolt to conform to the tapered surface of the liner hole when assembled.  These ridges plastically deform during assembly to take the individual shape of the tapered liner seat, creating a solid surface to tighten against.  A correctly seated and tightened assembly does not come loose.  This saves expensive maintenance hours, as the mill does not have to be shut down to tighten loose bolts or for leakage problems.

RidgebackTM Solution:  Notice the well seated bolt.	Seating Problem:  Standard mill liner bolts may have an issue with properly seating.