The thickness definition system for end caps includes several concepts. The calculated thickness δ is the thickness calculated using formulas from various chapters. The design thickness δd is the sum of the calculated thickness δ and the corrosion allowance C2. The nominal thickness δn is the design thickness δd plus the negative deviation of the steel thickness C1, rounded up to the standard steel specification, i.e., the thickness marked on the drawing. The effective thickness δe is the nominal thickness δn minus the corrosion allowance C2 and the negative deviation of the steel thickness C1. The blank thickness δs = δ + C1 + C2 + Δ1 (first design rounding value) + C3 (processing thinning amount) + (second manufacturing rounding value). Furthermore, the minimum forming thickness refers to the thickness that must be guaranteed after hot-rolled cylinders or convex end caps are formed; its value is not less than the design thickness.
The main forming methods for end caps are stamping and spinning. Hot spinning forming utilizes the principle that the strength of metal materials decreases with increasing temperature, locally heating the area to be spun and then spinning it into shape. Hot spinning forming technology does not require expensive molds, is unrestricted in the production of non-standard sized heads, has relatively low production costs, high dimensional accuracy, and controllable final spinning temperature.