HR Slitting Line

An HR (Hot Rolled) slitting line is a specialized industrial setup that plays a crucial role in the metalworking industry, particularly in processing hot  rolled coils. Hot  rolled coils are produced by heating steel slabs to high temperatures and then rolling them into coils. These coils are known for their relatively rough surface finish compared to cold  rolled coils but offer high strength and are commonly used in applications where formability and surface finish are not as critical as in some other industries.

The HR slitting line is designed to cut these hot  rolled coils into narrower strips, which can then be used in various downstream manufacturing processes. The process starts with the coil being loaded onto an uncoiler. There are different types of uncoilers used in HR slitting lines. Some are equipped with hydraulic collapsible drums, which are beneficial as they protect the sublayer of the hot  rolled material. This is important because hot  rolled coils can be quite thick and heavy, and any damage to the inner layers during uncoiling can affect the quality of the final slit strips. Uncoilers can also be configured to support tensile uncoiling or manual material unloading, depending on the specific requirements of the operation. Additionally, they are available in single  head or double  head configurations. Double  head uncoilers can significantly improve efficiency as they allow for quicker coil changes, reducing downtime.

Once the coil is being fed from the uncoiler, the material passes through a series of components to prepare it for slitting. A start  up unit may be present to ensure a smooth entry of the strip into the line. In some cases, a loop is incorporated. The loop serves multiple purposes. It can help to store a small amount of material, which is useful when there are minor speed fluctuations in different parts of the line. For example, if the slitting section needs to briefly slow down for blade adjustment, the loop can supply the material continuously, preventing any stoppages in the overall process.

Before reaching the slitter, the strip may also pass through a scrap winder or chopper. This is used to remove the edge trim, which is the excess material on the outer edges of the coil. The scrap winder collects the trimmed material, while a chopper can cut it into smaller, more manageable pieces for disposal or recycling.

The slitting unit is the core of the HR slitting line. The slitting head arbors in high  quality HR slitting lines are often fixed in eccentric sleeves. This design ensures that even after the slitting blades are polished (which is necessary over time due to wear), the slitting angle remains constant. Some advanced slitting units are equipped with two slitter heads. This allows for simultaneous slitting and blade changing. When one set of blades is in use, the other set can be readied for the next operation. As a result, the production downtime is significantly reduced, leading to higher overall productivity. Hydraulic lock nuts are also commonly used in the slitting unit to enhance the precision of blade positioning.

After slitting, the material passes through a tension unit. This unit features pre  separation devices and a disengaging shaft, which make it easier to switch between different separating plates. A friction  type tensile working table is usually part of the tension unit, with the ability to adjust the tension using hydraulic or pneumatic power. In cases where the hot  rolled material has a coated surface, a roller  type tightening machine can be optionally installed to protect the coating during the tensioning process.

Finally, the slit strips are wound onto a recoiler. The recoiler in an HR slitting line can be fitted with a seamless hydraulic expansion coiler to safeguard the sublayer of the material. A material clamping device with stress  reducing characteristics is also present. This device helps to maintain the roundness of the drum when coiling strips of different thicknesses, ensuring that the coiling is firm, dense, and neat.

HR slitting lines find applications in various industries. In the automotive industry, they are used to produce components that require high  strength materials, such as parts for heavy  duty trucks. In the construction sector, the slit hot  rolled strips can be used for manufacturing structural steel elements, like beams and columns. The manufacturing industry also benefits from HR slitting lines, as they can be used to create parts for machinery and equipment that need to withstand high stress and heavy loads.