In the production of shaft kilns, the fracture of the flange connecting bolts of the hollow shaft of the mill and the flange bolts of the inlet and outlet spiral cylinders is one of the common failures. and broken. After the bolts are loose or broken, the ash powder enters the joint surface or the flange of the end face of the spiral cylinder. If the treatment is not timely or thorough, similar failures will occur repeatedly, and the failure cycle will be shortened. The common temporary treatment method is to remove the residual bolts and re-tapping to replace the bolts, or drill holes near the broken bolts, but the phenomenon of repeated failures is unavoidable.

Reasons for bolt breakage: some are shallow flange positioning, and the bolts are subjected to alternating bending for a long time during the operation of the mill, resulting in stress relaxation or fatigue fracture; another case is that the flange joint surface is not properly fitted, and the actual contact area Due to the static inertia at the moment of starting, a slight slip occurs between the active and passive parts, and the screw teeth are eventually cut off by the extrusion deformation of the flange over time. Therefore, the contact condition of the flange joint surface should be checked during installation to increase the actual contact area. Always check the pre-tightening of the bolts frequently to prevent loosening. If this kind of failure occurs many times, but the flange joint condition has not changed greatly, the qb20~25mm pin hole can be drilled symmetrically in the flange 180~azimuth, and the positioning pin (both shear resistance) can be tightly fitted. Because the cylindrical surface of the positioning pin is in contact with the flange, when the flange joint surface is slightly displaced, the ability of the pin to withstand extrusion is much greater than that of the bolt. Under the action of preload, there is still a large frictional force transmission between the two joint surfaces, and the transmission is mainly realized by frictional force, and the slight slip caused by inertial action at the moment of starting is weakened or weakened by the resistance of the cylindrical pin. Avoid, so although the pin is small, it plays the role of protecting the bolt to a certain extent.