Manufacturing method of 1.5D elbow

The invention discloses a manufacturing method of a 1.5D elbow, which comprises the followings steps: steel plate blanking, barrel rolling, welding, shaping, process head welding, heating processing, heat treatment, groove processing, nondestructive detection and finished product testing. The key improvements are as follows: the diameter of a heating coil is larger than the diameter of a steel pipe, and the heating coil is fixedly arranged relative to a steel pipe pushing device; the axis of the heating coil is not coincident with the axis of the steel pipe, and the heating coil is arranged in a leaning way relative to the outer ring side of the steel pipe after bending. The invention has the advantages that: the distance between the heating coil and the inner ring side of the elbow is smaller than the distance between the heating oil and the outer ring side of the elbow, and the temperature of the inner ring side is higher than that of the outer ring side in the electrifying and heating process of the heating coil, therefore, the molecules of steel material of the inner ring side of the elbow are more active than the molecules of steel material of the outer ring side of the elbow, thereby ensuring that the wall thickness is not excessively reduced when the outer ring side is extended in the bending process; and the temperature of the inner ring side is high so as to facilitate the metal to flow, thereby being not easy to crease, improving the yield of the elbow and reducing economic losses.