Machines used for cutting hard surfaces, such as concrete and asphalt pavement, rock and the like, employ rotatable tools having a tapered forward cutting end behind which is an axially extending shank rotatably fitted in a tool holder. Where a quick-change tool holder is employed, the tool holder itself has a tapered forward end behind which is an axial shank that is received in the bore of a base block mounting on a machine. Base block mountings are secured to a rotatable wheel or drum, which forces the forward cutting ends of the tools retained in the various tool holders against the hard surface to be cut.
Where such tools are used to cut hard material such as asphalt or concrete, the tools retained in the quick-change tool holders must rotate to wear evenly around their circumference and thereby maximize their useful life. The hard material engaged by such tools none the less wears the tool rapidly. When the machine is used to cut hard surfaces it is common to replace the tools therein at least once a day. The same hard use that causes the tools to become rapidly worn eventually causes wear to the tool holders that receive the rotatable shanks of the tools. Although the life expectancy of such tool holders may be one hundred times or several hundred times the life of the tools received therein, extended usage of a machine will result in the tool holders becoming worn and requiring replacement.
It has become common to use a quick-change tool holder having a tapered forward end and an axially rearwardly extending shank that is received in a complementarily shaped bore of a base block mounting on the machine to simplify the replacement of worn tool holders. The distal end of the shank of the quick-change holder is threaded and extends beyond a rearward surface of the base block mounting, and a nut threaded on the distal end of the shank retains the quick-change tool holder in the base block mounting. Preferably, the quick-change holder is of the type disclosed in my previously issued U.S. Pat. Nos. 6,371,567 B1 and 6,585,326 B2, which are incorporated herein by reference.
Ideally, such quick-change tool holders are easily removed from the base blocks on the machine by using a punch and hammer to withdraw the shank out of the bore of the base block mounting. The strong forces applied to the tools, the tool holders, and the base block mountings, as the machine cuts hard surfaces, however, can cause the various parts to become deformed such that the shank of the quick-change tool holder can't be easily extracted from the bore of a base block mounting. The hard material cut by the machine also produces fines that work their way between the surfaces of the various parts and further inhibit the movement of one part with respect to another. As a result of the forgoing, it is often difficult to remove the shank of a quick-change tool holder from the bore of a base block mounting.
Presently, it is the practice to use a hammer and a punch or the like against the distal end of the shank of the tool holder to drive the shank out of the bore of the tool holder. Where the shank has become tightly bound into the bore of the tool holder, however, driving a worn shank out of a tool holder may be exceedingly difficult.
An alternative method of extracting such tool holders is to apply a tool against the radial flange that defines the rearward end of the tapered forward portion of the quick-change tool holder. The tool holder may include a notch or another configuration to allow the forward end of a punch or the like to be applied to the rear surface of the radial flange and facilitate the removal of the quick-change tool holder.
It sometimes occurs that the tapered forward end of a quick-change tool holder will become broken off during usage, leaving the shank thereof still lodged in the bore of the mounting block. In such a case, a machine operator cannot use a punch and hammer against the rear surface of the radial flange to remove the remnants of the shank of the quick-change tool holder and is limited to using a punch to drive the remnants of the shank forward through the bore.
It is also difficult for a machine operator to reach all the base block mountings for which the quick-change tool holders must be replaced. To improve the accessibility of the various base block mountings and tool holders, the operator must periodically operate the machine to partially rotate the drum and thereby bring previously inaccessible base block mountings into his reach. Where a damaged quick-change tool holder must be pounded out of its mounting block, the drum must be rotated so that the damaged parts are most accessible to the operator before removing the worn part. The process of removing damaged quick-change tool holders, therefore, can consume a great amount of time. Such down time has been greatly reduced by the provision of the quick-change tool holders, but it would, none the less, be desirable to provide an improved method and apparatus for removing a worn quick-change tool holder from a base block mounting. It would be further desirable to provide a method and apparatus for removing the remaining shank of a quick-change tool holder after the forward end thereof has been broken off.