Cutting blade for producing a tapazoidal groove in pavement and its associated method of manufacture

A cutting tooth element for a cutting blade. The cutting tooth element has a body. The body has a forward surface, a rearward surface and a peripheral edge surface that extends from the forward surface to the rearward surface. The peripheral edge surface has a constant width that is equal to the width at the bottom of the groove that is to be cut. The body of each cutting tooth has a thickened area between its forward surface and rearward surface. The thickened area has a maximum width equal to the width at the top of the groove that is to be cut. The body has sloped side surfaces that extend from the thickened area to the forward surface, rearward surface and the peripheral edge surface. The resulting shape of the cutting tooth causes the cutting tooth to retain its cutting profile as it wears.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to cutting blades that are designed to cut into pavement materials, such as concrete and asphalt. More particularly, the present invention relates to blades that cut grooves into pavement that are wider at the top than at the bottom.

2. Prior Art Description

Most all paved surfaces are impervious to water. Consequently, any low-point or depression in a paved surface has the potential to cause puddling during a rain storm. If the paved surface is an airport runway, for example, such puddling can be extremely dangerous. If the wheels of an airplane roll through a puddle during takeoff or landing, the wheels of the airplane can hydroplane. This can cause the airplane to turn on the runway and/or prevent an airplane from stopping or reaching takeoff speeds prior to the end of a runway.

It is for these reasons that many airports cut grooves into the surfaces of the paved runways. According to U.S. federal safety regulations, runway grooves should be ¼ inch wide, inch deep and should be spaced less than two inches apart. In theory, the grooves provide flow channels for water. Any water on the runway should flow into the grooves and should flow to the sides of the runway. This prevents puddles from forming on the paved surface.

Traditionally, grooves are cut into the pavement of a runway using a standard diamond embossed cutting blade. The cutting teeth on the blade have a uniform thickness. Consequently, when the blade cuts into the pavement it produces a groove that has a rectangular cross-sectional profile.

Grooves with rectangular cross-sectional profiles have sharp edges at the top of the groove. These top edges tend to chip and wear when contacted by airplane wheels, snow plows and other vehicles. Furthermore, wear due to freeze-thaw cycles and other weathering also causes these corners to chip and fall away. The chipped material from the top edge of a rectangular groove falls into the groove, therein causing small obstructions. These small obstructions catch dirt, tire rubber and other debris. Soon, the groove is clogged and cannot effectively channel water. The grooving then becomes ineffective and dangerous puddling can occur.

To prevent grooves from becoming clogged with debris, many airports perform runway cleaning as part of their periodic maintenance schedule. Cleaning removes collected debris from the grooves so that the grooves maintain their ability to channel water. The cost of cleaning runways is substantial in terms of both labor and equipment. Furthermore, the runways of an airport must be periodically closed during cleaning maintenance.

In the prior art, attempts have been made to produce grooves that do not have rectangular shaped cross-sectional profiles. If a groove can be made with sloped sides, then the sharp top edge can be eliminated. This would cause less wear, less debris and therefore would reduce the need for maintenance.

In U.S. Pat. No. 5,311,705 to Zuzelo, entitled Contoured Cutting Tool, a blade is shown having teeth with a triangular profile. Such blades do initially create a groove in pavement that is V-shaped. However, the shape of the cutting teeth causes the cutting teeth to wear unevenly. Consequently, after a short time, the shape of the groove being cut changes and eventually returns to a rectangular shape. The cutting blades must therefore be replaced very often during cutting. Since the blades contain diamond dust and are very expensive, the cost of cutting non-rectangular grooves soon becomes cost prohibitive.

A need therefore exists for a pavement cutting blade that can cut a non-rectangular groove, yet does not wear rapidly. In this manner, shaped grooves can be cut into airport runway pavement in an economically efficient manner. This need is met by the present invention as described and claimed below.

SUMMARY OF THE INVENTION

The present invention is the cutting tooth configuration for a circular blade, the resulting blade and the method of cutting a groove using the invented blade. The purpose of the present invention is to provide an effective and economical means for cutting a groove in pavement where the top of the grove is significantly wider than the bottom of the groove. To accomplish this goal, a new cutting tooth element is provided. The cutting tooth element has a body comprised, at least in part, of a diamond impregnated metal. The body has a forward surface, a rearward surface and a peripheral edge surface that extends from the forward surface to the rearward surface. The peripheral edge surface has a constant width that is equal to the width at the bottom of the groove that is to be cut.

The body of each cutting tooth has a thickened area between its forward surface and rearward surface. The thickened area has a maximum width equal to the width at the top of the groove that is to be cut. The body has sloped side surfaces that extend from the thickened area to the forward surface, rearward surface and the peripheral edge surface. The resulting shape of the cutting tooth causes the cutting tooth to retain its cutting profile as it wears. A trapezoidal shaped groove can, therefore, be cut by the blade and maintained as the cutting teeth wear.

DETAILED DESCRIPTION OF THE DRAWINGS

Although the present invention can be used to cut a groove with a trapezoidal cross-section into any surface, such as a roadway or a parking lot, it is particularly well suited for grooving the pavement of an airport runway. Accordingly, the present invention will be described in the application of cutting grooves in an airport runway in order to present the best mode contemplated for the invention. However, it should be understood that the present invention blade can be used for other applications and its use in cutting the pavement of a runway should not be considered a limitation.

Referring toFIG. 1, a blade assembly10is shown. The blade assembly10has a circular metal blank12with an arbor hole14positioned in its center. The arbor hole14is shaped and sized to enable the blade assembly10to be attached to a traditional pavement cutting machine.

A plurality of cutting teeth20are symmetrically disposed around the circular metal blank12. Each of the cutting teeth20is identical in shape, size and construction. The cutting teeth20are evenly distributed around the circular metal blank12so that the blade assembly10remains balanced, even at high rotating speeds.

Referring toFIG. 2, it can be seen that the purpose of the blade assembly10is to cut a groove18that has a trapezoidal cross-sectional profile into the pavement22of a runway. For an airport runway, the desired groove18has a depth D1of ¼ inch. The width W1of the groove18at the bottom26of the groove18is also ¼ inch. However, the width W2of the groove18at the top24is between 150% and 250% wider than the width W1at the bottom26. Consequently, the walls28defining the groove18diverge at an angle with respect to the vertical plane.

Each cutting tooth20has a complex shape. The cross-sectional shape of each cutting tooth20varies along the entire length of the cutting tooth20. As will be explained, the purpose of the complex shape of each cutting tooth20is to ensure that the cutting tooth20cuts the desired trapezoidal shaped groove18as the cutting tooth20continues to wear away.

Referring toFIG. 3andFIG. 4in conjunction withFIG. 2, it can be seen that each cutting tooth20has the same complex shape. Each cutting tooth20has an outer peripheral edge surface30that is curved, wherein the curvature of the peripheral edge surface30is concentric with the curvature of the circular metal blank12. The peripheral edge surface30is the surface of the cutting tooth20that lay the farthest from the center of the circular metal blank12. The peripheral edge surface30has a width that is equal to the desired width W1at the bottom of the groove18being cut.

Each cutting tooth20has a forward surface32and a rearward surface34. Each cutting tooth20also has two contoured sides36that extend between the forward surface32and the rearward surface34. Lastly, each cutting tooth20has a bottom edge38that faces the center of the circular metal blank12. The forward surface32and the rearward surface34of the cutting tooth20have generally rectangular cross-sectional profiles. The width of the forward surface32and the rearward surface34is preferably equal to the width of the peripheral edge surface30, and thus the width W1of the bottom26of the groove18that is to be cut.

The contoured sides36of each cutting tooth20have a complex shape. A slope transition point40is located in the middle of each contoured side36. The transition point40is located a distance D2below the middle of the outer peripheral edge surface30. The distance D2is equal to the desired depth D1of the groove18that is to be cut. A first transition line42extends from the transition point40to the middle apex of the bottom edge38of the cutting tooth20. The cutting tooth20is at its thickest along the first transition line42. The thickened area of the cutting tooth20along the first transition line42has a width equal to the desired width W2of the top24of the groove18that is to be cut.

A second transition line44extends from the transition point40to the corner where the outer peripheral edge surface30meets the forward surface32of the cutting tooth20. Likewise, a third transition line46extends from the transition point40to the corner where the outer peripheral edge surface30meets the rearward surface34of the cutting tooth20. The three transition lines42,44,46divide each contoured side36of the cutting tooth20into three sloping surfaces. The first sloping surface48is defined by the forward surface32, the bottom edge38, the first transition line42and the second transition line44. The cross-sectional thickness of the cutting tooth20at the first sloping surface48increases from its thinnest point at the forward surface32to its thickest point at the first transition line42.

The second sloping surface49is defined by the rearward surface34, the bottom edge38, the first transition line42, and the third transition line46. The cross-sectional thickness of the cutting tooth20at the second sloping surface49decreases from its thickest point at the first transition line42to its thinnest point at the rearward surface34.

The third sloping surface50is defined by the outer peripheral edge surface30, the second transition line44, and the third transition line46. The cross-sectional thickness of the cutting tooth20is complex along the third sloping surface50. The cross-sectional thickness increases from its thinnest point along the outer peripheral edge surface30to its thickest point at the transition point40where the second and third transition lines44,46converge.

Referring toFIG. 5, it can be seen that each cutting tooth20has an inert base section52and a diamond impregnated cutting section54. The complex shape of the cutting tooth20is reflected in both the shape of the inert base section52and the shape of the diamond impregnated cutting section54. The diamond impregnated cutting section54is the only part of the cutting tooth20that actually cuts into pavement during use. The diamond impregnated cutting section54contains diamond particles and is, therefore, expensive. The use of the inert base section52prevents expensive diamond material from being used in the part of the cutting tooth20where it would serve no purpose. The use of the inert base section52, therefore, greatly reduces the cost of the overall cutting tooth20. Furthermore, the material of the inert base section52can be selected to optimize its ability to be welded or otherwise bonded to the selected material of the circular metal blank12(FIG. 1).

Referring back toFIG. 2, it will be understood that the part of the cutting tooth20that forms the bottom26of the groove18cuts longer and through more material than other parts of the cutting tooth20. This fact is reflected in the design of the cutting tooth20. The contoured sides36of the cutting tooth20are configured to wear in a manner that maintains the selected shape of the groove18as the cutting tooth20wears away. In this manner, although the cutting tooth20does wear, the wear is evenly distributed and the cross-sectional shape of the groove18being cut does not significantly change.

In the selected embodiment of the cutting tooth20, the groove18that is created has a trapezoidal cross-section. It will be understood that other shapes can be created by varying the surfaces of the cutting tooth20. For example, the walls28of the groove18and/or the bottom26of the groove18can be made to be curved. Furthermore, the angle of the walls28can be varied to any acute angle. All such variations, modifications and alternate embodiments are intended to be included within the scope of the present invention as defined by the claims.