US Patent 10066446 Tapered spline connection for drill pipe, casing, and tubing

An apparatus comprises a first number of splines located near a first end of a first joint section and a second number of splines located near a second end of a second joint section. The first number of splines extends in an axial direction of the first joint section and spans a circumferential surface of the first joint section. Each of the first number of splines has a base, a tip, and a pair of flanks that extends from the base to the tip and forms an acute angle. Each of the first number of splines are configured to be received between adjacent pairs of splines in the second number of splines as the first end of the first joint section and the second end of the second joint section are joined.