- BACKGROUND OF THE INVENTION
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.
- SUMMARY OF THE INVENTION
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.
BRIEF DESCRIPTION OF THE DRAWINGS
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:
FIG. 1 is an exploded side view of a tool and tool holder having a wear ring in accordance with the invention, with the inner portions of the parts shown in broken lines;
FIG. 2 is a side-elevational view, taken partly in cross-section, of the tool, tool holder, and wear ring depicted in FIG. 1 in assembled form;
FIG. 3 is an isometric view of the tool and wear ring shown in FIGS. 1 and 2 prior to the tool being inserted into the tool holder;
FIG. 4 is a front-elevational view of the wear ring shown in FIGS. 1 through 3;
FIG. 5 is a side-elevational view of the wear ring shown in FIG. 4;
FIG. 6 is a front-elevational view of the working end of an extraction tool for extracting the tool having the wear ring shown in FIG. 4;
FIG. 7 is an exploded isometric view of the extraction tool shown in FIG. 6 and the tool, tool holder, and wear ring shown in FIGS. 1 and 2;
FIG. 8 is an isometric view of the extraction device fitted around a tool and tool holder having a wear ring in accordance with the invention; and
FIG. 9 is a front elevational view of a second embodiment of a wear ring according to the invention;
FIG. 10 is a front elevational view of a third embodiment of a wear ring according to the invention;
FIG. 11 is a front elevational view of a fourth embodiment of a wear ring according to the invention; and
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
FIG. 12 is a front elevational view of a fifth embodiment of a wear ring according to the invention.
Referring to FIGS. 1 and 2, a tool 10 is suitable for being rotatably mounted in a tool holder 11 having a planar forward surface 12 and a bore 13, the axis of which is perpendicular to the forward surface 12. The tool holder 11 may be mounted directly to the drum or wheel of the machine or may be a quick-change holder as depicted. The tool 10 includes a tool body 14 having a tapered forward cutting portion 15 at the forward end of which is a seat into which is brazed a hardened cutting tip 16. The cutting portion 15 flares outwardly near its rearward end to a flange 18 having a generally planar annular rearward surface 20. Extending axially rearwardly from the center of the annular rearward surface 20 is a cylindrical shank 22 having an enlarged hub 24 at the distal end thereof. The hub 24 forms a shoulder 26, and fitted forwardly of the shoulder 26 is a compressible sleeve 28 made of a suitable spring steel.
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.
Referring to FIGS. 1 through 5, fitted around the compressible sleeve 28 is a wear ring 44 having a planar forward surface 45, a parallel planar rearward surface 46, and outer surfaces 47, 48, 49, 50, 51, 52, 53, 54. Surfaces 47 and 51 are both planar and parallel to one another and are located on opposing portions of the wear ring 44. Surfaces 49 and 53 are also planar and parallel to each other, are located on opposing portions of the wear ring 44, and are perpendicular to surfaces 47 and 51. Surfaces 48, 50, 52, 54 are all arcuate and preferably form arcuate sections of the same cylinder.
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 FIG. 3, prior to insertion of the shank 22 of the tool 10 into a bore 13 of a tool holder 11, the wear ring 44 is fitted around the central portion of the circumference of the sleeve 28 with the arcuate portion 60 extending across the edges 30, 32 of the slot therein.
Referring specifically to FIGS. 1, 3, and 4, and as disclosed in my co-pending application, Ser. No. 10/952,158, the inwardly directed protrusion of the arcuate portion 60 compresses the sleeve 28 to a diameter that is less than the inner diameter of the bore 13 of the tool holder 11. The distal end of the shank 22 of the tool 10, including a portion of the sleeve 28 can then be manually inserted by a machine operator into the bore 13 using only one hand. The machine operator will be able to insert the distal end of the shank 22 until the rearward surface 46 of the wear ring 44 contacts the planar forward surface 12 of the tool holder 11. Thereafter, the cutting tip 16 of the tool 10 is pounded with a hammer to drive the shank 22 with the sleeve 28 thereon into the bore 13 of the holder 11. As the shank 22 is driven into the bore 13 the wear ring 44 is moved forwardly along the sleeve until the arcuate protrusion 60 thereof drops into the cut out portion 36, 38, 40, 42, after which the sleeve 28 can expand to the full diameter of the bore 13 of the tool holder 11.
Referring to FIGS. 1 and 3, the axial walls 36, 40 of the cut out portions at the forward end of the sleeve 28, as it is being compressed by the wear ring 44, are spaced further apart from each other than the width of the arcuate portion 60 of the wear ring 44 as defined by the distance between the sides 61 and 62. Accordingly, when the shank 22 of the tool 10 is driven entirely into the bore 13 of the tool holder 11, the wear ring 44 will be forced to the forward end of the sleeve 28 and the arcuate portion 60 will drop between the axial walls 36, 40 of the compressible sleeve 28. When this occurs, the compressible sleeve 28 will be released from beneath the arcuate portion 60 and allowed to expand. Since the diameter defined by semi-cylindrical portion 56 is larger than the diameter of the inner bore 13 of the tool holder 11, the compressible sleeve will expand until the outer surface thereof contacts the inner surface of the bore 13 of the tool holder 11. The tool 10 will thereafter be retained within the bore 13 of the tool holder 11 by the radially outwardly applied force of the partially compressed sleeve 28. Furthermore, the wear ring 44 will be retained against rotation with respect to the sleeve 28 by the contact of the sides 61, 62 of the arcuate portion 60 against the axial walls 36, 40 of the cut out portions at the forward end of the sleeve 28. Accordingly, the wear ring 44 is prevented from rotating with the tool 10 and will not cause rotational wear to the forward surface 12 of the tool holder 11.
Referring to FIGS. 1, 2, and 4, the distance 65 between the parallel outer surfaces 49, 53 and between parallel surfaces 47, 51 is significantly less than the outer diameter 66 of the radial flange 18 and is also substantially less than the diameter 67 across the forward surface 12 of tool holder 11. As a result, when the wear ring 44 is fitted around the shank 22 between the rearward surface 20 of the flange 18 and the forward surface 12 of the tool holder 11, a pair of opposing gaps 67, 68 are formed adjacent surfaces 47, 51 (best shown in FIG. 2) and similar gaps (not shown) are formed adjacent surfaces 49, 53. Preferably, for tools 10 used in the road planning industry, the rearward surfaces 20 of the tool 10 and the forward surface 12 of the tool holder 11 have diameters of about 1.5 inches, and the distance 65 is generally no greater than 1.25 inches. Preferably, there is between one-eighth inch to one-quarter inch of the width of the rearward surface 20 and on the forward surface 12 of each gap 67, 68 to allow an end extraction tool 70 to be inserted in the gaps 67, 68 between the surfaces 12, 20.
Referring to FIGS. 6, 7, and 8, to remove the shank 22 of the tool 10 from the bore 13 of the tool holder 11, an extraction tool 70 is provided having forked end consisting of spaced apart parallel prongs 72, 73. As best shown in FIG. 6, the prongs 72, 73 are spaced apart a distance that is a little greater than the distance 65 between the spaced parallel surfaces 47, 51 or between surfaces 49, 53 of the wear washer 44. The inwardly directed sides 74, 76 of the prongs 72, 73 respectively are tapered such that the tapered inner sides will fit in the gaps 67, 68 adjacent the surfaces 47, 51 of the wear ring 44. The extraction tool 70 includes an impact portion 78 that can be struck by the head of a hammer, not shown, while the prongs 72, 73 are fitted in the gaps 67, 68 to thereby remove the tool 10 from the tool holder 11.
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 FIG. 9, wear ring 90 has opposing parallel side surfaces 92, 93 that are spaced apart a distance 94 that will allow gaps between the two surfaces 12, 20 into which the prongs 72, 73 of a removal tool 70 can be inserted. Referring to FIG. 10, wear ring 100 has a cylindrical outer surface 102 with an outer diameter 104 that is significantly less than dimensions 65 and 67 to allow the use of the tool 70. Similarly, in FIG. 11 wear ring 110 has six outer surfaces 112, 113, 114, 115, 116, 117 defining a hexagon with the spacing 118 between parallel surfaces sized to allow gaps sufficient for use of the tool 70. And, finally, in FIG. 12, wear ring 120 has two sets of parallel sides 121, 122, and 123, 124 configured into a square with the spacing between parallel sides having the needed dimension 125.
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.