Lofting and unfolding method for round-sky and square-earth base

The invention relates to the technical field of ship construction, and discloses a lofting and unfolding method for a round-sky and square-earth base, which comprises the following steps: S1, drawing a three-dimensional diagram of a neutral line of an outer plate of the round-sky and square-earth base, and rounding a rectangle of a lower opening; s2, the outer circle of the upper opening is equally divided according to the set number, all fillets of the rectangle of the lower opening are equally divided, and bisectors are obtained; s3, respectively expanding a triangular plane ABC and an adjacent conical curved surface ABD in the neutral line three-dimensional diagram to obtain an expanded plane graph; and S4, repeating the step S3 to obtain an expanded view of other triangular planes and the conical curved surface. Lofting and unfolding are carried out by taking a three-dimensional diagram of the neutral line of the outer plate as a reference, meanwhile, a lower opening rectangle of the neutral line is chamf