US 20060125306 A1
A tool has a tapered forward cutting end behind which is a cylindrical shank. A rearwardly facing annular flange separates the forward cutting end from the shank. The shank is received in a tool holder having a planar forward surface, and fitted around the shank of the tool is an annular wear ring. The outer diameter of the wear ring is less than the outer diameter of the radial flange and less than the diameter of the forward end of the tool holder. The thickness of the wear ring forms a gap on opposite sides of the wear ring between a portion of the tool holder and a portion of the radial flange of the tool. Spaced apart prongs of an extraction tool can be fitted into the gaps to extract the tool from the tool holder.
1. The combination comprising:
a tool having a tapered forward cutting end, a rearwardly facing radial flange at a rear of said tapered forward cutting end, said radial flange having a diameter defining a first dimension, and a cylindrical shank extending axially rearward of said radial shank,
a tool holder having a forward surface, a cylindrical bore opening in said forward surface, an outer surface intersecting an outer peripheries of said forward surface wherein diametrically opposing portions of said intersecting surfaces define a second dimension,
a wear ring on said shank between said radial flange and said forward surface, said wear ring having an outer end defining a width, said width having a third dimension that is less than both said first dimension and said second dimension wherein a spacing remains between a portion of said flange and a portion of said forward surface, and
an extraction tool having a pair of parallel members defining a fork and an impact portion that can be struck by the head of a hammer wherein a portion of said parallel member is receivable in said spacing for removing said tool from said tool holder and wherein a hammer strike against said impact portion will aid in the removal of said tool from said tool holder.
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The present invention relates to rotatable tools used in machines to cut hard surfaces and to an improved wear ring between the tool and the tool holder adapted to receive an extraction device for extracting the tool from the tool holder.
Machines for cutting hard surfaces such as used in the trenching and mining industries and for highway cold planning to remove the upper surface of concrete and asphalt pavement, employ tools fitted into tool holders on a rotatable wheel or drum. The tools have a tapered forward cutting end and axially behind the cutting end is a cylindrical shank that rotatably fits within a complementarily shaped bore in the tool holder. Such rotatable tools have an annular rearwardly directed flange between the forward cutting end and the shank that contacts the forward surface of the tool holder. The shank is retained in the bore of the tool holder by a sleeve made of spring steel so as to be compressible and has an unstressed diameter greater than that of the bore, such that compression of the sleeve retains the sleeve within the bore of the tool holder. To prevent the withdrawal of the tool from the tool holder, the sleeve has one or more inwardly directed projections in the inner surface that engage an annular shoulder around the circumference of the shank of the tool.
To maximize the useful life of such tools, the tools are adapted to rotate around the axis of the shank thereby causing the tool to wear evenly about its circumference. A tool in a machine may undergo 50,000 rotations or more during a single work day, and the rotation of the rearwardly directed flange against the forward surface of the tool holder will over time cause the forward surface of the tool holder to become worn away. To prevent such wear, it is common to provide an annular wear ring around the shank of the tool between the forward surface of the tool holder and the rearwardly directed flange of the tool.
To operate properly, the wear ring must remain stationary against the forward surface of the tool holder while the tool rotates. In my co-pending application filed Sep. 28, 2004 and issued Ser. No. 10/952,158, I disclose a wear ring having an inwardly directed projection on the inner opening thereof that will engage portions of the upper end of the compressible sleeve to prevent the wear ring from rotating with respect to the tool holder while the tool is in use. In the same application I disclose that an enlarged diameter of the wear ring can be used to facilitate the extraction of the tool from the tool holder. There are circumstances, however, when it is not desirable to have a wear ring, the outer diameter of which is larger than the diameter of the radial flange of the tool. In such circumstances, it is desirable to provide an alternative method of extracting the tool from the tool holder.
Briefly, in the present invention a tool is provided having a tapered forward cutting end with a hardened tip at the forward end thereof. At the rearward end of the forward cutting end is a rearwardly facing annular flange having a first diameter, and extending axially from the rearwardly directed annular flange is a cylindrical shank. Fitted around the cylindrical shank is a compressible sleeve for retaining the shank of the tool in the tool holder.
The tool holder for receiving the shank of the tool has a generally planar forward surface and centrally located in the forward surface is a perpendicularly oriented bore. The outer surface of the tool holder in the proximity of the forward surface is generally frustoconical and opposing portions of the intersection of the forward surface with the frustoconical side surface defines a second dimension.
A wear ring for use with the tool has planar forward and rearward surfaces and an inner opening sized to receive the shank of the tool. The periphery of the wear ring has a pair of opposing parallel planar surfaces and the distance between the planar surfaces is less than the first dimension and less than the second dimension. Accordingly, when the shank of the tool is first inserted through the central opening of the wear ring and then received into the bore of the tool holder, the wear ring will space the rearwardly directed radial flange of the tool from the forward surface of the tool holder. Also, since the distance between the opposing parallel outer surfaces of the wear ring are less than the diameter of the radial flange of the tool and less than the distance across the forward end of the tool holder, a gap exists between a portion of the rearwardly directed radial flange of the tool and the forward surface of the tool holder.
In accordance with the invention, an extraction tool having a pair of parallel members spaced apart a distance a little greater than the distance between the parallel spaced surfaces of the wear ring is positioned in the gaps between the rearwardly directed flange and the forward surface and a hammer or the like can be used to pound against a surface of the extraction tool to thereby remove the rotatable tool from the tool holder.
A better understanding of the present invention will be had after a reading of the following detailed description taken in conjunction with the drawings wherein:
The compressible sleeve 28 generally defines a hollow cylinder with an elongate slot extending axially in the length of the wall forming parallel spaced slot edges 30, 32. The sleeve 28, as described herein, is of the type disclosed in my co-pending application, Ser. No. 10/952,158 and has at the forward end of the sleeve 28 adjacent slot edge 30, is a cut out portion defined by an axial wall 36 and an arcuate wall 38. Similarly, at the forward end of the second slot edge 32 is a second cut out portion defined by an axial wall 40 and an arcuate wall 42.
The wear ring 44 also has a central opening including a semi-cylindrical portion 56 that defines approximately 300 degrees of a circle, and at the ends of the semi-cylindrical portion 56 are radially outwardly extending notches 57, 58. Between the notches 57, 58 is a radially inwardly extending arcuate portion 60 having sides 61 and 62. The inner surface of the arcuate portion 60 defines a cylinder having a center co-axial with the center of the semi-cylindrical portion 54 but having a radius R1 that is substantially less than the radius R2 of the semi-cylindrical portion 56. The diameter of the opening defined by semi-cylindrical portion 56 is greater than the diameter 64 of the tool holder 11.
As shown in
Referring specifically to
While the present invention has been described as employing a wear ring having a radially inwardly directed projection 60 that engages portions of the compressible sleeve 28 to thereby prevent rotation of the wear ring, the invention may be employed on any rotatable tool having a wear ring between the rear surface of the tool and the forward surface of the wear ring. The configuration of the inner opening of the wear ring is not a necessary element of the invention.
It should be appreciated that the outer surface of the wear ring may have any of a number of configurations as long as the wear ring allows opposing gaps between the rearwardly directed surface 20 of the tool and the forward surface 12 of the tool holder. Referring to
While the invention has been described with respect to a single embodiment, it will be appreciated that many modifications and variations may be made without departing from the true spirit and scope of the invention. It is therefore the intent of the appended claims to cover all such modifications and variations which fall within the spirit and scope of the invention.