In forging each kind of forging, the first to calculate the material, forging in the forging of the weight and consumption for cutting. (the basic formula to calculate material G = rho V G - the proportion of rho - the weight of the blank material V - the volume of a billet) calculate way, must calculate the volume of raw materials (because of all sorts of different proportion of raw materials) and then multiplied by the proportion of the weight of the forgings, any kind of forging in the forging and closely related to the volume before and after, when forging such as pier coarse, long drawing, punching and pulling long mandrel, shoulder, moving, bending and torsion. Its overall volume remains the same, while its shape changes, such as from circle to square, from square to circle, from octagon to circle, but its volume remains the same.

2. Principle of least resistance

Before forging, the specified process and the selection of equipment, must consider the deformation law of the workpiece, free forging when the basic process, auxiliary process, plastic process three categories.

Such as pier: the workpiece axial force and radial no resistance, along the axial transformation to radial flow, axial resistance by radial flow faster. The resistance path flows slowly in the axial direction.

Drawing length: rectangular section and circular section drawing length, mainly feed and pressure, if the use of the upper and lower flat anvil drawing length, the narrower the width of the anvil, the axial resistance is the least, and the longitudinal resistance is large, so the axial flow is larger than the longitudinal flow.

V-shaped anvil pulling: if the upper and lower v-shaped anvil is used to pull the length (referring to the round material), the lateral flow is limited, forcing the metal to flow along the axial direction, the pulling speed is increased. The same is true of the upper and lower semicircular anvil.

Horse rod expanding hole: in the forging process, the anvil and the workpiece and the horse rod of the small contact surface friction effect, resistance small wall thickness thinning, expanding the inner and outer diameter.

Mandrel drawing length: generally with the upper and lower v-shaped anvil four angles to produce resistance workpiece and tooling contact surface reduction, forcing the metal along the axial flow, length increase. Therefore, the principle of least resistance is indispensable in the process of forging.