The hole types are divided into the following types according to their purpose:
(1) Open pass, also known as extension, rough rolling, or compression pass. The task of this pass type is sufficient to reduce the cross-section of the stainless steel alloy 440;
(2) Rough rolling pass, also known as rough rolling, shaping or forming pass. Its task is to continue reducing the cross-section of the rolled piece while gradually transforming it into a prototype similar to the finished product;
(3) Precision rolling pass, also known as pre rolling pass, refers to the last 3-5 passes within the finished pass;
(4) Finished pass, also known as finished pass, refers to the pass of the last rolled finished product.
The pass is divided into the following types based on the turning method of the pass on the roller:
(1) Open pass, that is, the roll gap S of the roller is located around the pass;
(2) Closed pass, which means that the roll gap s of the roller is outside the periphery of the pass;
(3) Half open (closed) hole type, also known as control hole type; The hole types are divided into the following types according to their punching special shaped spring sheet: round, square, rhombic, elliptical, hexagonal, flat, I-shaped, groove, rail shaped, and disc shaped hole types.