What are the methods of cold rolling?
The production methods of cold rolling can be divided into single sheet rolling and coil rolling.
(1) Single sheet rolling.
(1) Single sheet rolling.
The two-roll mill was first used in monolithic rolling, and four-roll cold rolling mill is widely used at present. Four-high cold rolling mill can be divided into reversible and irreversible according to the direction of roll operation. When the irreversible four-high rolling mill is used for monolithic production, the rolling operation is to feed the steel plate into the mill manually one by one. After rolling the whole stacked steel plate one by one, the stacked steel plate is hoisted to the mill by crane for the next rolling, so that the rolling cycle can be carried out until the specified size of the finished product is reached.
When the reversible rolling mill is adopted, there are two rolling operations: one is to roll each steel plate on the mill back and forth until the final product size is rolled, and then to roll the second steel plate. Although this method of operation is frequently operated, it is not easy to scratch the surface of the product. Therefore, it is widely used in actual production, especially in rolling heavy and large-sized steel plates. The other is that each steel plate is fed into the rolling mill one by one, and then returned to the second rolling pass one by one after the whole stacked steel plate has been rolled one by one. This operation method makes the size of rolling products more uniform, and saves the adjustment time of roll reversal and pressing so that the output of cold rolling mill is higher, but scratches may sometimes occur between plates.
Because tension cannot be used in single sheet rolling, the reduction rate of each pass is generally not more than 14%. The rolling passes increase, and the degree of work hardening of steel plate increases. Therefore, single sheet rolling cannot produce cold rolled products with very thin thickness.
(2) Coil rolling.
When the reversible rolling mill is adopted, there are two rolling operations: one is to roll each steel plate on the mill back and forth until the final product size is rolled, and then to roll the second steel plate. Although this method of operation is frequently operated, it is not easy to scratch the surface of the product. Therefore, it is widely used in actual production, especially in rolling heavy and large-sized steel plates. The other is that each steel plate is fed into the rolling mill one by one, and then returned to the second rolling pass one by one after the whole stacked steel plate has been rolled one by one. This operation method makes the size of rolling products more uniform, and saves the adjustment time of roll reversal and pressing so that the output of cold rolling mill is higher, but scratches may sometimes occur between plates.
Because tension cannot be used in single sheet rolling, the reduction rate of each pass is generally not more than 14%. The rolling passes increase, and the degree of work hardening of steel plate increases. Therefore, single sheet rolling cannot produce cold rolled products with very thin thickness.
(2) Coil rolling.
At present, coil rolling is mostly used in cold rolling production. Its basic form is divided into single-machine coil rolling and multi-strand continuous coil rolling. Coil rolling adopts irreversible and reversible cold rolling mills such as two-high mill, four-high mill, partial eight-high mill, Twelve-high mill, and twenty-high mill.
There are two main types of single hunger irreversible cold rolling mill. There are hundreds of such mills in our country. The length of roll body is between 100-600 mm and the diameter of the roll is between 100-300 mm. Most of these rolling mills have uncoilers and coilers. These mills are mainly used to produce narrow strips below 600 mm or flat rolled narrow strips with rolling speed ranging from 1.2 to 2.0m/s.
There are two main types of single hunger irreversible cold rolling mill. There are hundreds of such mills in our country. The length of roll body is between 100-600 mm and the diameter of the roll is between 100-300 mm. Most of these rolling mills have uncoilers and coilers. These mills are mainly used to produce narrow strips below 600 mm or flat rolled narrow strips with rolling speed ranging from 1.2 to 2.0m/s.
The single reversible cold rolling mill is divided into the four-high mill and multi-high mill (partial eight-high mill, Twelve-high mill and twenty-high mill). Most rolling mills are driven by working rolls, which can reduce the total deformation resistance, reduce energy consumption and roll thinner products.
Compared with single stand reversible cold rolling mill, multi-stand continuous cold rolling mill has the following characteristics:
(1) high rolling speed, generally above 25m/s (up to 41 m/s).
(2) The product quality is good, and it can meet the requirements of mechanical properties, surface quality, thickness and accuracy put forward by users.
(2) The product quality is good, and it can meet the requirements of mechanical properties, surface quality, thickness and accuracy put forward by users.
(3) Both ends of the coil can be pressed down, which reduces the loss of cutting head and tail, and the metal yield is high.
(4) The output is high, and the annual output is generally in the hundreds of thousands of tons to more than 1 million tons.
(5) Hydraulic screwdown device and a series of automatic control and various new technologies are adopted, and their advantages are more prominent.
(5) Hydraulic screwdown device and a series of automatic control and various new technologies are adopted, and their advantages are more prominent.
