Patent Application
20070182238
The present invention relates to pavement routers or routers. More particularly, the present invention relates to a replaceable cutter for use in a pavement router.
For over 30 years, pavement cracks in both asphalt and concrete pavement have been mechanically widened and made deeper in order to define a proper reservoir configuration for optimum sealant performance. Cracks that appear in pavement are major causes of reduced useful life of the pavement. In order to extend the useful life of the pavement, the pavement cracks that appear are typically widened and made deeper to define the above noted reservoir. After definition of the reservoir, sealants are injected into the reservoir in order to minimize the on-going damage to the pavement caused by the pre-existing crack.
The first cutters were vertical spindles and proved to be very slow in operation. Next came steel star cutters that were significantly more productive than the first cutters but had the deficiency of wearing out very quickly. See prior art
Additionally, the oversized diameter of the arbor permitted the introduction of grit between the cutter pin 4 and the arbor, resulting in increased wear of the cutter 1. This further resulted in increased down time of the pavement router due to the fact that the cutters 1 needed more frequent replacement.
There is a need then in the industry for a cutter that produces a clean and spall-free reservoir in asphalt and concrete pavements. Additionally, it would be advantageous to have a cutter whose arbor dimensions more closely approximate those of the cutter pin in order to minimize the introduction of grit therein.
As noted above, the cutters utilized with pavement routers are typically mounted on cutter pins. The cutter pins extend between two spaced apart discs. The distance between the two discs is known. The cutter of the present invention has a hub that has width dimension that is only slightly less than the known distance between the two discs. Accordingly, no washers or only a single pair of washers are utilized to take up space on the cutter pin adjacent to the wide hub cutter, unlike the prior art discussed above. By providing a relatively wide hub, the wobble of the cutter on the cutter pin is significantly reduced with no other changes to the cutter. Additionally, in a preferred embodiment, the arbor defined in the hub of the cutter of the present invention has a reduced diameter dimension in order to more closely approximate the diameter of the standard diameter cutter pin. This closeness of fit between the cutter pin and the arbor results in two significant improvements. The first is that the wobble of the cutter on the cutter pin and the up-down motion of the cutter relative to the cutter pin are both significantly reduced. Secondly, by having a relatively close tolerance between the cutter pin and the arbor, grit is substantially precluded from entering into the space defined by the interface between the exterior margin of the cutter pin and the interior margin of the arbor, thereby minimizing cutter wear at that interface. Thirdly, having a wide hub increases the bearing surface between cutter and cutter pin, which reduces wear at that interface.
The present invention is a cutter for use with a pavement router, the pavement router having a pair of cutter supports, the cutter supports being spaced apart a known distance, the cutter includes a plurality of blades disposed radially about a hub, the hub being operably coupled to each of the plurality of blades and having an arbor defined therein along a longitudinal axis, the hub having a certain width dimension taken along the longitudinal dimension, the width dimension being substantially coextensive with the known distance that the cutter supports are spaced apart so that the hub extends substantially from cutter support to cutter support when disposed between the pair of cutter supports. The present invention is further a method of forming a cutter for use with a pavement router.
A typical pavement router is shown generally at 10 in
The frame assembly 12 has a generally planar main support 20. A handle 22 is coupled to and extends rearward of the main support 20. A suspension 24 depends from the main support 20. A pair of spaced apart wheels 26 is rotatably coupled to the suspension 24. The wheels 26 may be power driven or the router 10 may be propelled by the operator exerting a force on the handle 22. A drag 27 may extend rearward and a shield 28, comprising depending chains, may be positioned forward.
The second subcomponent of the pavement router 10 is the engine assembly 14. The engine assembly 14 includes an engine 30 supported on the main support 20. A fuel tank 32 is disposed forward of the engine 30. A battery 34 is mounted at a rear margin of the main support 20. The battery 24 provides ignition and cranking energy to the engine 30.
The output of the engine 30 is supplied to a clutch unit 36. The clutch unit 36 includes a clutch 38. The clutch 38 is manually operated by a clutch control 40, including a dead man control mounted on the handle 22.
The clutch unit 36 is rotatably coupled to drive belt assembly 41. The drive belt assembly 41 includes a drive sheave 42 and spaced apart driven sheave 44. A belt 46 rotatably couples the drive sheave 42 to the driven sheave 44.
The cutter head assembly 16 is depicted in
A plurality of cutter pins 60 extend between the two cutter discs 58 to support a plurality of cutters 70, described in greater detail below. Each cutter pin 60 acts as an axle for a respective cutter 70. A first end of the cutter pin 60 is supported in a blind bore 62 defined in a first cutter disc 58. The second end of the cutter pin 60 is supported in a bore 64 defined through the second cutter disc 58. An exposed portion 68 of the cutter pin 60 extends between the two cutter discs 58. The cutter pin 60 is held in place by a shiftable pin retainer 69 coupled to the exterior margin of the second cutter disc 58.
The cutter of the present invention is shown generally at 70 in
A plurality of blades 86 extend radially outward from the hub 72. Preferably, there are eight blades 86. Each of the blades 86 has a blade root 88 that is joined to the hub 72 at the rounded junction 76. Each blade 86 is tapered, narrowing outward, and having a leading edge 90 and a trailing edge 92. An outer margin 94 extends between the leading edge 90 and the trailing edge 92. The outer margin 94 is angled such that the greatest radial measurement of the blade 86 is found at the intersection of the outer margin 94 and the leading edge 90. A cutting edge 96 is defined at the outermost portion of the leading edge 90. The cutting edge 96 may be carbided or otherwise treated or coated in order to improve the longevity of the cutter 70.
In assembly, a cutter 70 is disposed between the two cutter discs 58 with the arbor 82 in registry with the bores 62, 64 defined in the respective cutter discs 58. A cutter pin 60, preferably having a generally standard diameter of 22.23 mm (0.875 inches) is slid into the bore 64, through the arbor 82 and into the bore 62. The cutter pin 60 is then captured in this disposition by the pin retainer 69. There is a relatively close fit between the inner margin of the arbor 82 and the outer margin of the cutter pin 60. This fit is preferably less than 0.254 mm (0.010 inches) and is preferably between 1.778 mm (0.070 inches) and 0.00254 mm (0.001 inches). This close fit substantially prevents the cutter 70 from wobbling on the cutter pin 60 and further minimizes radial displacement of the cutter 70 relative to the cutter pin 60. As noted in
The above disclosure is not intended as limiting. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the restrictions of the appended claims.
