Wear collar device for rotatable cutter bit

#The present invention relates to cutter bits and more particularly relates to cutter bits of the type used in excavation applications such as in trenching, road scarifying or the like. The present invention is especially concerned with a new and improved construction of a mounting block for rotatably supporting a cutter bit by means of a detachable and replaceable wear collar member which operates to support the bit in the block. The general purpose of such wear collar member being to reduce the wear on the bit and block, and especially the block since it is relatively expensive to replace, as compared to the bit. In addition, such wear collar member adds a support and stabilizing factor to the bit to afford uniform rotational movement to the bit and hence, to promote uniform wear on the working bit surfaces.

#The present invention relates to a mounting block assembly which incorporates a detachable and replaceable wear collar member for rotatably supporting a cutter bit within such block. Heretofore, such cutter bits have included the type generally known as conical bits or pik-bits of the type used for construction and excavation applications. For example, such cutter bits are generally utilized with such mounting blocks which are detachable or fixably mounted on an excavating wheel of a trenching machine or on the drive wheel of a road scarifying machine or the like. Such cutter bits are illustrated, for example in U.S. Pat. Nos. 3,841,708 and 4,201,421.

#Heretofore, there has been a need to mount such cutter bits in a rotatable relationship relative to the blocks so as to minimize wear between the component parts while permitting easy assembly and replacement of the parts when necessary. It is especially important to minimize the wear on the mounting blocks themselves as their cost for replacement is relatively high compared to the replacement cost of the bits. It will be recognized, however, that it is also important to minimize, to the greatest extent possible, wear on the bits since a relatively substantial number of bits are required for each such excavating machine and oftentimes a full set of bits (i.e. 500 or more) are replaced after merely a few hours of operation due to damage and/or wear. In addition, it is important to support and stabilize the bit to the greatest extent possible so as to promote the generally concentric uniform rotational movement of the bit relative to the block thereby to promote uniform wear on the bit. In this case, it will be recognized that such uniform wear increases the overall wear-life of the bit.

#FIG. 1 is a generally side elevation view of the mounting system of the present invention illustrating a cutter bit mounted for substantially free-rotation within a mounting block, and with the wear collar member detachably mounted on the block and supporting the cutter bit in the installed position thereof; and

#FIG. 2 is a fragmentary, vertical section view, on an enlarged scale, representing in more detail the features of the invention illustrated in FIG. 1 thereof.

#Referring again to the drawings and in particular to FIG. 1 thereof, there is illustrated the mounting assembly, designated generally at 2, of the present invention. As generally illustrated, the assembly includes a mounting block member 4 which has an internal bore, as at 5, for mounting in a substantially free-rotational relationship a cutter bit 6. The cutter bit is generally of a conventional construction recognized in the field as a pik-type bit which has a cylindrical body portion 7 which merges into a conical carbide tip portion 10. The rearward portion of the cutter bit includes a cylindrical shank 12 which is mounted for substantially free-rotation within the bore 5 by means of a resilient retainer element, as at 14, which has a plurality of dimples, as at 16, for co-acting engagement within a groove, as at 13, provided in the block member for retaining the cutter bit against axial movement as known in the art and as generally described in U.S. Pat. No. 3,841,708. As shown, the bit element 6 has a pair of parallel, laterally spaced shoulder members 18 and 22 separated by a groove 20 with the shoulder portion 18 having an inclined tapered surface 24 which provides a cam-like seat 24 of a generally conical configuration.

#Now in the invention, the wear collar member 8 is of a cylindrical configuration having a cylindrical inlet opening 29 which opens onto an inclined tapered surface 32 which provides a cam-like seat surface for the confronting tapered conical surface 24 of the shoulder portion 18 on the cutter bit 6. By this arrangement, the wear collar member provides a cam-like seat so as to give a surface-to-surface friction contact between the wear collar member and the confronting conical surface of the shoulder portion 18 of the cutter bit to stabilize and hence, to afford a more uniform wear between the component parts. As to the collar member itself, it includes a body 30 having a curved or radius surface, as at 34, which merges into an integral annual flange 36 which has a transverse dimension to slidably fit over and around the confronting circular end portion, as at 37, of the mounting block member 4.

#In the invention, the collar member 8 is detachably mounted on the cylindrical portion 37 of the mounting block member 4 by means of a resilient ring element, as at 42. The ring element 42 is preferably made from an elastomeric or polymeric material having high strength yet good flexibility characteristics. For example, an elastomeric material would include a neoprene rubber while a polymeric material would include nylon, Teflon or the like. As illustrated, the resilient element 42 is disposed within a semicircular groove, as at 38, provided in the mounting block member and in a corresponding semi-circular groove, as at 40, provided in the integral flange portion 36 of the wear collar member 8. By this arrangement, the resilient member 42 provides an effective snap-action interconnection between the wear collar member 8 and the mounting block member 4.