Disc cutter and method of replacing disc cutters

Abstract

An improved rolling disc type cutter, and novel cutterheads employing such cutters. The cutter includes a washer surface and a cutter ring assembly. The cutter ring assembly further includes an annular cutter ring with an interior annulus defining portion and an outer ring portion. A bearing assembly substantially fits into the annulus of the cutter ring in a close fitting relationship with the shaft, so that the cutter ring may rotate with respect to and be supported by said shaft. The bearing assembly includes a bearing and a seal which fits between the washer surface and the cutter ring to form a lubricant retaining seal for the interior annulus portion of the cutter ring. A retainer assembly is used to retain the cutter ring assembly on the shaft, and a cap seals the interior annular portion of the cutter ring assembly so that, in cooperation with the seal and the cutter ring, a lubricant retaining chamber is provided. This simplified cutter design is achieved by using a comparatively large stiff shaft which is preferably in the range of 40-50% of the cutter ring diameter. The stiff shaft design permits cantilever mount of the cutter on a cutterhead. The design allows increased loading of the disk cutter footprint, and permits single disc cutter technology to be applied to small bits or cutterheads. Also, hard metal cutting edge inserts with reduced leading and trailing edge surface curvature are provided.