Double taper lock system for a locking a mixer shaft in a quill

Abstract

A system for automatically centering and rigidly retaining a mixer shaft in a mixer drive. A hollow quill in a mixer drive is provided with an axial bore having a first diameter along a central portion thereof and tapering linearly and axially in opposite directions away from the central portion with increasing diameter to define a pair of opposed conical portions of the axial bore on either side of the central bore. A smooth-surface cylindrical mixer shaft inserted into the bore is retained by the tightening of upper and lower tapered cylindrical locks which are slidable along the mixer shaft and have conical outer surfaces which are matable with the upper and lower conical portions of the quill bore. The locks, when urged into wedged relationship between the shaft and the quill bore, automatically center the shaft in the quill in rigid retention. The upper end of the shaft is provided with a thrust plate secured by throughbolts into the quill to press the upper lock into locking relationship. At the lower end of the quill, a bearing retainer ring threaded onto the outer surface of the quill is bored to receive bolts extending through a flange on the lower lock to press the lower lock into locking relationship. The rigidity of the lock increases the first critical frequency of the mixer system and therefore permits operation at high speeds, including rotational frequencies greater than the first critical (natural) frequency of the mixer system.