BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates generally to the field of grinding wheels. More specifically, the present invention discloses a grinding wheel assembly for grinding grooves into road pavement for striping and the like.
Statement of the Problem
A variety of devices have been used in the past for grinding or cutting grooves in roadway pavement. For example, this process is often an initial step in striping a roadway. Paint or material having a distinctive, contrasting color is then deposited into the recessed area created by grinding. The recessed area helps to protect the paint for abrasion and weathering. Grinding is also used to remove existing striping prior to repainting or for other road maintenance operations. Finally, grinding can also be used to create a pattern of recesses in the pavement to provide an audible warning of lane departure for the vehicle driver. The roadway pavement is typically asphalt, macadam or concrete, although other types of paving materials are known in the industry.
Conventional pavement grinding machines have a number of significant shortcomings. In particular, they tend to be relatively slow (often traveling a small fraction of a mile per hour), and typically require frequent replacement or maintenance of the bits or grinding surface. These limitations significantly increase the time and expense required for a given job. Therefore, a need exists of a pavement grinding machine that can operate more rapidly and is also durable, so that maintenance or replacement of the bits is not required as frequently.
Solution to the Problem
The present invention addresses these shortcomings in the prior art by providing a grinding wheel assembly with polycrystalline diamond bits in a unique staggered pattern that allows the grinding wheel to rotate at higher velocities without excess bit wear. These elements not only allow the present device to grind more rapidly, but also significantly increase the useful life of the bits.
SUMMARY OF THE INVENTION
This invention provides a grinding wheel assembly for grinding grooves in road pavement that employs a rotating wheel having a generally cylindrical shape with a plurality of parallel tracks spaced around the periphery of the wheel and running across the face of the wheel. A plurality of blocks are removably secured to these tracks. Each block has a pattern of holes for removably engaging bits positioned to grind parallel grooves in the road pavement as the wheel rotates. The bit patterns are arranged so that bits on adjacent blocks are not aligned to hit the same groove in the road pavement, but bits on selected non-adjacent blocks are aligned to hit the same groove during rotation of the wheel. Preferably, the bits have a conical, polycrystalline diamond tip and a cylindrical base that allows the bits to be removed from the holes in the blocks, rotated and then reinserted in a different orientation to enable different aspects of the tips to be used during grinding.
These and other advantages, features, and objects of the present invention will be more readily understood in view of the following detailed description and the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention can be more readily understood in conjunction with the accompanying drawings, in which:
FIG. 1 is a front view of a machine incorporating an embodiment of the present grinding wheel assembly 10.
FIG. 2 is a right side view corresponding to FIG. 1.
FIG. 3 is a side view of the grinding wheel assembly 10.
FIG. 4 is a front view of the grinding wheel assembly 10 corresponding to FIG. 3.
FIG. 5 is a side view of the wheel 11.
FIG. 6 is a front view of the wheel 11 corresponding to FIG. 5.
FIG. 7 is a front view of a block 20.
FIG. 8 is a front view of a block 20 holding a number of bits 30.
FIG. 9 is a right side view of the blocks 20 and bits 30 corresponding to FIG. 8.
FIG. 10 is a perspective view of a bit 30.
FIG. 11 is a front view of a bit 30 corresponding to FIG. 10.
FIG. 12 is a cross-sectional view of a bit 30 corresponding to FIG. 10.
FIG. 13 is a cross-sectional view of a segment of road pavement 50 showing a set of grooves 40a made by a first set of bits 30 as the grinding wheel assembly 10 is rotated.
FIG. 14 is a cross-sectional view of a segment of road pavement 50 corresponding to FIG. 13 showing the sets of grooves 40a and 40b made by two laterally-offset sets of bits.
FIG. 15 is a cross-sectional view of a segment of road pavement 50 corresponding to FIG. 13 showing the sets of grooves 40a-40c made by three laterally-offset sets of bits.
FIG. 16 is a cross-sectional view of a segment of road pavement 50 corresponding to FIG. 13 showing the sets of grooves 40a-40d made by all four laterally-offset sets of bits.
DETAILED DESCRIPTION OF THE INVENTION
FIGS. 1 and 2 show front and side views, respectively, of a machine for grinding stripes in road pavement. In particular, the grinding wheel assembly 10 includes a wheel 11 having a generally cylindrical shape with opposing lateral sides, as shown in FIGS. 3 and 4. An axle 12 extends laterally outward from the sides of the grinding wheel assembly 10 along a central horizontal axis, as shown in FIG. 4, and is used to rotate the grinding wheel assembly 10 during grinding operations. A conventional motor powers the axle 12 and grinding wheel assembly 10.
As illustrated in FIG. 5, the wheel 11 has a plurality of parallel tracks 14 spaced around its periphery and running across the cylindrical face of the wheel. For example, the tracks 14 can run parallel to the central axis of the wheel (i.e., horizontally during normal operation). In the embodiment shown in FIGS. 5 and 6, the tracks 14 are rectangular recesses running completely across the peripheral surface of the wheel 11 from side to side. It should be understood that the tracks 14 could have other cross-sectional shapes, or run only part of the way across the peripheral surface of the wheel 11, etc.
Blocks 20 are removably secured to the tracks 14 of the wheel 11, as shown in FIGS. 3 and 4. Detail views of the block 20 are shown in FIGS. 7-9. For example, each block 20 can include a rectangular ridge 26 that seats in a corresponding track 14. This embodiment simplifies manufacture of the tracks 14 and blocks 20, and also allows a range of sliding movement between track 14 and block 20 during installation and maintenance. The blocks 20 can be secured in place in the tracks 14 by means of bolts that are inserted through aligned holes 24 in the blocks and threaded holes 16a-16d in the wheel 11 (shown in FIG. 6). It should be noted that the lateral position of each block 20 in its track 14 with respect the lateral sides of the wheel 11 is determined by a staggered pattern of bolt holes 16a-16d used to secure each block 20 to a track 14 in the wheel 11. For example, as shown by the pattern of threaded holes 16a-16d in FIG. 6, each block 20 can be shifted laterally by a small increment with respect to the lateral sides of the wheel 11.
Bits 30 are removably secured to the blocks 20 in a predetermined pattern to grind parallel grooves 40 in the road pavement as the wheel 10 rotates and the assembly moves along the road pavement. In the preferred embodiment of the present invention shown in FIGS. 10-12, each bit 30 has a substantially conical, polycrystalline diamond tip 32 extending from a generally cylindrical base 36. For example, the base 36 can be made of tungsten carbide. A thin cobalt layer 34 joins the tip 32 to the base 36. Alternatively, the bits 30 could have flat tips.
The base 36 of each bit 30 is removably seated in a hole 22 in a block 20 and secured in place by a friction fit, as depicted in FIGS. 8 and 9. After a period of operation in grinding, the bits 30 can be removed and replaced, or alternatively the bits 30 can be rotated about their longitudinal axis and reseated in the holes 22 in the block 20 in a different orientation so that a different aspect of the bit tip is used for grinding. This is similar to rotating a pencil so that its tip wears evenly. In one embodiment of the present invention, the bit holes 22 extend through the block 20, so that the bits 30 can be punched out of the holes 22 in the block 20 by a force exerted on the base 36 of the bit 30 from the rear of the block 20.
As previously discussed, the bits 30 are secured to the blocks 20 (and in turn to the wheel 11) in a predetermined pattern to grind parallel grooves 40 in the road pavement 50 as the wheel rotates and the assembly moves along the road pavement. But, the bits 30 on each block 20 are arranged so that bits 30 on adjacent blocks are not aligned to hit the same grooves 40 in the road pavement 50. Instead, the bits 30 on selected non-adjacent blocks are aligned to hit the same grooves 40 in the road pavement 50 during rotation of the grinding wheel assembly 10.
In the embodiment of the present invention shown in FIGS. 4 and 6, each quadrant of the wheel 11 carries four blocks 20 that are laterally shifted with respect to one another so that so that none of the grooves 40 cut by the bits 30 on the four blocks 20 coincide. Instead, each set of grooves is shifted to the right by an increment determined by the shift in the threaded holes 16a-16d used to mount the blocks 20 to the tracks 14 in the wheel 11, as shown in FIG. 6. These four sets of grooves 40a-40d cut by the bits 30 on these four blocks are illustrated in FIGS. 13-16, respectively. In other words, only the bits 30 on every fourth block 20 hit the same set of grooves 40 (i.e., one block 20 in each quadrant of the wheel 11 hits each set of groove 40). This 1:4 ratio is a matter of engineering design, and it should be understood that other ratios could be employed.
The specific embodiment of the block 20 shown in FIGS. 7 and 8 has a pattern of fourteen holes 22 arranged in two rows of seven. It should be noted the pattern of bit holes 22 is the same in each block 20, but the four staggered lateral offsets of the blocks 20 produce a total of fifty six parallel grooves, as shown in FIG. 16. However, this specific configuration is entirely a matter of engineering design. The parallel grooves 40 can be closely spaced to overlap to a degree and form a recessed strip of a desired width. The same end result could also be accomplished by varying the pattern of bit holes 22 on the blocks 20. In other words, four different bit hole patterns could be formed on the block 20 in place of employing staggered lateral offsets to mount the blocks 20 to the tracks 14 in the wheel 11.
The above disclosure sets forth a number of embodiments of the present invention described in detail with respect to the accompanying drawings. Those skilled in this art will appreciate that various changes, modifications, other structural arrangements, and other embodiments could be practiced under the teachings of the present invention without departing from the scope of this invention as set forth in the following claims.
Patent Application
20170022674
