Blade for cutting concrete

#This invention relates to blades used to cut concrete.

#As concrete slabs harden the concrete shrinks and cracks form. Grooves are placed in the slabs so that these cracks form along the grooves rather than form randomly throughout the slab. In small concrete surfaces, these grooves are formed by hand operated grooving trowels which push the aggregate in the concrete aside to form the groove and in the process form a thin cement layer on the surface of the groove. The groove may have to be troweled several times in order to maintain the shape of the groove. These grooves have rounded edges and may also have flattened areas by the grooves left from the trowels. These rounded edges are aesthetically pleasing to many people and reflect a hand finished slab of concrete.

#On large slabs of concrete, hand troweling of grooves is impractical. The hand troweling of the grooves must be done while the concrete is soft enough for the trowel to push the aggregate aside, and at that stage the concrete is not hard enough support the weight of the person troweling the groove. It is impractical to support people over large slabs of concrete to perform the troweling. Repeatedly troweling the grooves is also expensive, and for large slabs of concrete the costs are further increased.

#These as well as other features of the present invention will become more apparent upon reference to the drawings in which like numbers refer to like parts throughout, and wherein:

#FIG. 1 shows an end view of a concrete cutting blade of this invention;

#FIG. 2a shows a cross-section of the blade of FIG. 1;

#Referring to FIGS. 1-3, a concrete cutting blade 10 has disc 12 with a hole 14 therein for mounting to a drive shaft of a motor (not shown) on a concrete cutting saw. The saw can have wheels, a skid plate, or both. The disc rotates about the longitudinal axis of the drive shaft which extends through the hole 14. The blade 10 has a cutting segment 16 that has a central, pilot segment 18 in the middle of two side cutting segments 20a, 20b, which are mirror images of each other.

#Referring to FIG. 2b, the cutting segment 16 is described in more detail. The central or pilot segment 18 extends radially away from the rotational axis 22 (FIG. 2a) about which disc 10 rotates. As used herein, the radial direction is orthogonal to the rotational axis 22. The side segments 20 have a concave portion that tangentially joins the pilot segment 18. The concave portion is preferably, but optionally a radiused portion having a radius between about ⅛ to ½ inch (about 4-13 mm), and more preferably between about ¼ and ⅜ inches (about 6-10 mm), and ideally about ¼ inches (about 6 mm) in radius. Larger radii could be used, but are not as desirable. Advantageously, the side cutting segments 16 extend along the rotational axis a distance corresponding to the radius of the concave portion. This axil distance is greater than the width of the pilot segment 18 measured along the rotational axis.

#The side segments 20 extend axially, parallel to the rotational axis 22 a predetermined distance. As used herein, the axial direction is parallel to the rotational axis 22. Preferably, but optionally, the side segments 20 have a convex shoulder 24 that the curves toward the rotational axis 22. Preferably, but optionally, the radiused juncture between the pilot segment 18 and the side segments 22 is tangential to the pilot segment 18 and tangential to the shoulder 24. Advantageously, the shoulder 24 is radiused, with a radius about half that of the concave radius 22 joining the pilot segment to the shoulder 24, but curving in the opposite direction. For a blade 10 having a diameter of about 5 inches (about 180 mm) the cutting segment 16 is about ⅝ inches (about 16 mm) wide measured along the rotational axis 22.