The spiral convex and concave mold is divided into a convex mold and a concave mold. It is a volumetric mold and requires a certain matching clearance and contact area. When milling the spiral groove on the milling machine, the spiral groove is milled whether it is a spiral on the groove or on the bottom of the groove. The spirals have equal leads. Because when the workpiece rotates one week, the distance that the milling cutter moves in the axial direction relative to the workpiece is equal to the lead, but the calculation formula of the helix angle is tanβ=πD/P_z, on a spiral groove, from the notch to the bottom of the groove, The helix angle at different diameters varies with the diameter D of the workpiece. Due to the different angles of the helix angle β, the direction of the tangent on the same section is also different. Interference is often generated during machining, that is, the cutter turns the spiral during the milling process. The lower part of the groove is cut in a part to make the cross-sectional shape of the groove deviate, so that the milling