(1) Different shapes:

Theelliptical head, also known as the elliptical head, is composed of half an elliptical sphere and a cylindrical straight side section. It has the advantages of the hemispherical head having good force and the shallow depth of the dish-shaped head. Since the curvature of the warp of the ellipse is smooth and continuous, the stress distribution in the head is relatively uniform. Dish-shaped heads, also known as spherical heads with folded edges, also known as butterfly-shaped heads. It is composed of a spherical surface, a straight side of a cylinder with a certain height, and a transitional part connecting the above two parts with a radius of curvature smaller than the radius of the spherical surface.

(2) Different forces:

The elliptical head is better in force than the dish-shaped head, but the elliptical head of the same diameter is deeper than the dish-shaped one, and the manufacturing difficulty is slightly greater than that of the dish-shaped one. It consumes more materials, and the wood is higher. Some, and the difference in volume is still small.