Skid plate for a concrete saw

This application claims the benefit under 35 U.S.C. § 119(e) of provisional application Ser. No. 60/576,476, filed Jun. 3, 2004, the complete contents of which is incorporated herein by reference.

Slotted skid plates are used with concrete saws to cut concrete before it is hardened to the green stage. This is described in U.S. Pat. No. 4,769,201. But the concrete is very abrasive. Thus, the skid plates are made of steel to resist the wear from sliding over the concrete surface and to resist the wear from the abrasive concrete carried by the blade at the cutting edge and which widens the slot in the skid plate. The skid plates were made of sheet steel and bent to the desired shape. But the steel skid plates warp during manufacture and use and that causes raveling as the cut concrete grooves ravel unless the skid plates are flat against the concrete during cutting. There is thus a need for an improved skid plate that remains flat against the concrete after manufacture and during use.

One patent addresses this problem of the non-flat skid plates by using a truss to warp the skid plate into a desired configuration, as described in U.S. Pat. No. 5,507,273. But adjusting the truss and fixing the truss to lock in the desire distortion is complex and time consuming. Indeed, it is so difficult that special equipment and methods are used, as described in U.S. Pat. No. 5,689,072. There is thus a need for a better way to achieve a flat skid plate during cutting. A less expensive way to make skid plates is also desirable.

The skid plates are fastened to the saw by inserting pins through holes in the distal ends of spring loaded pistons The pistons resiliently urge the skid plate against the concrete surface during cutting. Because the alignment of the skid plate with the saw blade affects the quality of the groove cut in the concrete, the pins holding the skid plate to the saw have a very tight fit with the mating holes in the pistons. But removing the pins is difficult because the pins often freeze in place. The skid plates thus become difficult to remove and that encourages workers to leave them as long as possible, and often too long. Unfortunately, the skid plates wear, sometimes after as little as 1200 feet of cutting and the quality of the cut groove deteriorates with the wear. There is thus a need for a better way to fasten the skid plate to the saw and to make it easy to remove a used skid plate from the saw and to fasten a replacement skid plate to the saw.

A cast skid plate for a concrete cutting saw is provided. The saw has a rotating blade with sides and rotating about a rotational axis to cut a groove in a concrete surface during use of the saw. The skid plate has an elongated support portion having a longitudinal slot therein sized to fit within about ⅛ inch or less of the sides of the concrete cutting blade during use of the skid plate. The elongated support is slightly bowed an amount selected to substantially counteract bowing of the skid plate that occurs when the elongated support is urged against the concrete surface during cutting of the concrete. The bow is cast into the skid plate. At least one saw mounting portion is provided, and is offset from the elongated support. The elongated support and at least one saw mounting portion are also integrally cast with the skid plate.

Further variations of the cast skid plate cause the curvature of a bottom surface of the skid plate to extend beyond leading and trailing end portions of the skid plate by about ⅛ inch or less. The skid plate bows toward the concrete. Preferably there are two mounting portions forming a front and rear mounting portion, one each at an opposing end of the elongated support portion. Advantageously, but optionally, there is a front mounting portion having a front mounting yoke, and there is a rear mounting portion having a rear yoke. The elongated portion and at least one mounting portion are preferably cast of metal other than iron, preferably aluminum, but could be cast of a polymer or of a ferrous alloy.

In a further variation the cast skid plate has two mounting portions, one of which comprises a slot extending along an axis toward and away from the elongated support portion and configured to receive a pin orientated generally parallel to the rotational axis. The other mounting portion comprises a slot that is generally parallel to the concrete surface during cutting. Preferably, but optionally, a snap lock or spring loaded clip holds a mating portion of the saw engaged in the vertical slot in order to provide for a quick-release connection with the skid plate.

In a further variation the skid plate has a leading and trailing end and the leading end of the skid plate has an end that is angled relative to the longitudinal slot. Moreover, the leading end of the skid plate preferably has a V shaped configuration in the plane of the elongated portion with the point of the V oriented away from a trailing end and toward the leading end and that helps shove concrete debris from cutting out of the way of the skid plate so the debris is not run over by the skid plate.

The skid plate preferably comprises a single part connected to the saw at opposing ends. But in a further embodiment the skid plate is formed by two separate segments each of which has a separate saw mount portion, and each of which has a slot therein which slot extends along a portion of the cutting blade during use of the saw.

There is also advantageously provided a skid plate having two saw mounting portions on the skid plate and an elongated support portion which are integrally cast of metal. The saw mounting portions are offset from the support portion a predetermined distance. An elongated slot is either cut into the support portion or integrally cast with the support portion. The slot is sized relative to the cutting blade to support the concrete surface during cutting so cutting does not produce unacceptable raveling of the cut groove during use of the skid plate. The skid plate is preferably cast of non-ferrous metal, but an iron based metal could be used, as could polymers. The leading end of the skid plate preferably, but optionally also has an angled end forming a V with the apex of the V facing forward and in the same plane as the slot. The support portion is also preferably, but optionally curved about an axis generally parallel to the first axis by an amount selected to at least partially offset the deformation of the skid plate occurring when the saw urges the skid plate against the concrete surface during cutting.

There is also provided a further skid plate having first means for mounting the skid plate to the concrete saw and second means for supporting the concrete surface during cutting. The first and second means are simultaneously and integrally cast. The first and second means are preferably formed of cast metal, and more preferably cast of a metal the dominant portion of which is other than iron. The first and second means could be cast of a polymer. The second means preferably, but optionally comprises a slot that is cut in the elongated portion after the elongated support skid plate and mounting portion are cast, but the second means could comprise a slot that is cast in the elongated portion. As with the prior embodiments, there is preferably an angled front end on the support portion.

A further embodiment uses a replaceable plate that removably fastens to the skid plate and abuts the bottom of the skid plate. Various fastening mechanisms can be used, including snap locks that cooperate with the sides or flanges on the skid plate, threaded fasteners that engage the skid plate at various locations, resilient prongs that engage the edges around holes or slots in the skid plate, and adhesives. The mechanisms for fastening the plate to the skid plate restrain the plate and skid plate from longitudinal movement, and lateral movement, so that a slot in the plate aligns with the blade extending through the slot in the skid plate, in order to prevent raveling of the concrete surface during cutting. The slot can be formed in the plate, or cut by the blade. The slot can end internally to the plate, or can extend to a trailing edge of the plate. A partial slot or widened slot can be used at the trailing end of the plate in order to avoid having the plate trowel over the cut groove.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a saw with a cast skid plate;

FIG. 2 is a top perspective view of the cast skid plate of FIG. 1;

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