Detailed introduction of rolling mill

Electroplated hard chrome processing Roller is a common working tool in the metal processing industry, mainly used in the processing of metal materials such as flattening, stretching, and curling. It is usually made of metal materials and has the characteristics of high strength, high hardness, high wear resistance and high durability. Rollers are usually used in the process of rolling steel, rolling aluminum, rolling metal strips, etc., and are widely used in steel, non-ferrous metals, ferroalloys and other industries.

Rollers are generally used in pairs of two or more to form a roll group. These rolls can be installed on the roll stand and driven by the transmission mechanism to rotate the rolls. During the working process, the metal material passes through the working area between the two rolls and is subjected to a large pressure, which causes the metal material to undergo plastic deformation and reduce its thickness.

The main components of the roll include the journal, drum, upper roller, lower roller, connecting rod, box door and automatic device. Among them, the journal is an important component connecting the roll and the roll stand. It bears a large axial force and bending force, and needs to have high strength and high wear resistance. The roller is the working part of the roller, which contacts the metal material and bears great pressure and friction, and needs to have high hardness and high wear resistance.

The manufacturing materials of the roller are usually alloy steel, high-speed tool steel, tungsten steel, carbide steel, etc. according to the strength, hardness and other requirements of different power rolling mills. According to different working requirements and the characteristics of the processed materials, the surface of the roller can be specially treated, such as grinding, polishing, carbide spraying, etc., to improve the working efficiency and service life of the roller.

The shape and size of the roller also vary according to different working requirements and the characteristics of the processed materials. Generally speaking, the roller can be divided into two types: working roller and support roller. The working roller is mainly used for flattening, stretching and curling metal materials, and has a larger diameter and a narrower working surface. The support roller is mainly used to support the working roller, maintain the stability of the metal material, and has a smaller diameter and a wider support surface.

In addition, there are some special types of rollers, such as spiral rollers, gear rollers, spare rollers, etc., which are used in different metal processing processes, making full use of the characteristics and advantages of the rollers, and improving work efficiency and product quality.

Forged steel rolls

Through smelting, forging and heat treatment, the forged steel rolls have uniform high hardness, high wear resistance and excellent accident resistance on the roll body working layer, while ensuring that the roll neck and roll body core have certain strength and high toughness. This unique property of forged steel rolls gives them irreplaceable advantages over cast rolls in cold rolling and non-ferrous rolling. According to the conditions of use, forged steel rolls can be divided into forged steel hot rolls and forged steel cold rolls. Forged steel hot rolls are mainly used for hot rolling blanks and rough rolling rolls for steel sections, while forged steel cold rolls are widely used for cold rolls. Forged steel cold rolls have high requirements for use. The surface of the roll body must have high and uniform hardness to ensure the dimensional accuracy and good surface quality of the cold-rolled strip or steel plate. The roll body has a certain depth of hardened layer and has high accident resistance. For this reason, the original organization of the roll is very strict, one is pure metallurgical quality, and the other is the uniformity of the organization. At present, my country mainly uses cold rolling roller materials containing about 2% chromium, and the working layer above HS90 is about 10mm. The newly developed Cr5 series cold rolling rollers contain 5% chromium, and the working layer above HS90 is more than 30mm. The excellent performance of the C5 series cold rolling working rollers in all aspects will gradually replace the traditionally used C2 series cold rolling rollers and become the development direction of cold rolling working rollers.

How would you solve the roller shaft repair problem?

A rolling mill is an equipment that realizes the metal rolling process, and generally refers to the equipment that completes the entire process of rolling material production. The working stand consists of rolls, rolling mill arches, bearing seats, bearings, self-contained rewinding and unwinding or rewinding and unwinding platforms, bases, roll adjustment devices, upper roll balancing devices and roll changing devices. The roll is the main working part and tool on the rolling mill that causes continuous plastic deformation of metal. It is mainly composed of three parts: the roll body, the roll neck and the shaft head.

The roller bearings of a company’s reciprocating rolling mill are worn. The wear depth is 0.7mm and the journal is 500mm. Call us to ask if we can repair it. After understanding the relevant data of the equipment and the on-site conditions, we decided to use the “Roll Repair Machine Processing Technology” to solve the problem of roll shaft repair. The repair material has good machining performance, meets the processing requirements of turning, milling, planing and grinding, and is not affected by thermal stress during the repair process. And the bonding performance of the material is also very good. At the same time, in the process of repairing the worn surface, the surface bonding area and bonding force of the material are increased through surface baking oil, surface grinding, absolute ethanol cleaning, etc. to ensure that the material does not Will fall off.

Regarding roll shaft repair, the advantages of our Sole carbon nanopolymer material repair technology go beyond the points mentioned above. We have strengthened predictive maintenance and used the Internet and sensing technology to assist users in implementing all-weather online monitoring, intelligent early warning and diagnostic analysis to promptly discover and eliminate hidden equipment faults to prevent risks and reduce equipment operating costs. We also focus on the core concerns of customers and use new generation information technologies such as the industrial Internet and AR virtual reality to build a product capability ecosystem of “data chain”, “service chain” and “supply chain” to achieve the integrated development of user needs and solution capabilities. .

Little knowledge about roll index

Regardless of hot rolling or cold rolling, the roll is a direct tool to achieve metal deformation during the rolling process. Therefore, the requirements for roll quality are strict. Its main quality requirements are strength, hardness and certain heat resistance. Roll strength is the most basic quality indicator. While meeting the strength requirements, it must also have a certain impact resistance toughness. To ensure that the roll has sufficient strength, the main considerations include selecting the roll material and determining a reasonable roll structure and size. Whether the strength is sufficient or not can be determined based on the calculation of the roll strength. Hardness usually refers to the hardness of the working surface of the roll and is also the main quality indicator of the roll. It determines the wear resistance of the roll. To a certain extent it determines the service life of the roll. Hardness requirements can be met through material selection and some kind of heat treatment on the roll surface. In addition, when the roll is working under hot rolling conditions, it should also have certain heat resistance to ensure product accuracy.

Classification and selection of rolls

1. Classification of rolls

There are many ways to classify rolls, the main ones are:

1) According to product types, they include strip steel rolls, profile steel rolls, wire rod rolls, etc.;

2) According to the position of the rolls in the rolling mill series, they are divided into blank rolls, rough rolls, finishing rolls, etc.;

3) According to the roller function, it can be divided into scale breaking roller, perforated roller, smoothing roller, etc.;

4) According to the roll material, there are steel rolls, cast iron rolls, carbide rolls, ceramic rolls, etc.;

5) According to the manufacturing method, there are cast rolls, forged rolls, cladding rolls, nested rolls, etc.;

6) According to the state of the rolled steel, it is divided into hot rolling rollers and cold rolling rollers. Various classifications can be combined accordingly to give the rolls a clearer meaning, such as centrifugally cast high chromium cast iron work rolls for hot rolled strips.

2. Selection of rollers

Commonly used roll materials and uses are shown in the table. The performance and quality of a roll generally depends on its chemical composition and manner of manufacture and can be assessed by its organizational, physical and mechanical properties and the type of residual stress present inside the roll (see Roll Inspection). The use effect of rolls in rolling mills not only depends on the roll material and its metallurgical quality, but also on the usage conditions, roll design, operation and maintenance.

The use conditions of rolls in different types of rolling mills are very different. The factors causing the differences are:

1) Rolling mill conditions. Such as rolling mill type, rolling mill and roll design, pass design, water cooling conditions and bearing types, etc.;

2) Rolling conditions such as rolled product varieties, specifications and deformation resistance, reduction system and temperature system, output requirements and operations, etc.;

3) Requirements for product quality and surface quality, etc.

Different types of rolling mills and rolling mills of the same type with different operating conditions have different performance requirements for the rolls used. For example, the billet and slab blooming mill rolls must have good torsional and bending strength, toughness, bite, and heat resistance. Crack resistance, thermal shock resistance and wear resistance; while the tropical finish rolling stand requires high hardness of the roll surface, resistance to indentation, wear resistance, resistance to spalling and resistance to thermal cracking.

What are the rollers used for?

The roller is an important part of the rubber machine in the rubber factory. It uses the pressure generated by a pair or a group of rollers to roll steel. It mainly bears the effects of dynamic and static loads, wear and temperature changes during rolling.

The main working parts and tools on the rolling mill that produce continuous plastic deformation of rubber. The roll mainly consists of three parts: roll body, roll neck and shaft head. The roll body is the middle part of the roll that actually participates in rolling metal. It has a smooth cylindrical or grooved surface. The roll neck is installed in the bearing and transmits the rolling force to the frame through the bearing seat and the pressing device. The transmission end shaft head is connected to the gear seat through the connecting shaft to transmit the rotational torque of the motor to the roller. The rolls can be arranged in the form of two-roller, three-roller, four-roller or multi-roller in the rolling mill frame.

There are many ways to classify rolls, the main ones are: (1) According to product type, they are divided into strip steel rolls, profile steel rolls, wire rod rolls, etc.; (2) According to the position of the rolls in the rolling mill series, they are divided into blank rolls, rough rolls, Finishing rolls, etc.; (3) According to the roll function, it is divided into scale breaking roller, perforated roll, smoothing roll, etc.; (4) According to the roll material, it is divided into steel roll, cast iron roll, cemented carbide roll, ceramic roll, etc.; (5) According to the roll material The manufacturing methods are divided into casting rolls, forging rolls, cladding rolls, nested rolls, etc.; (6) According to the state of the rolled steel, they are divided into hot rolls and cold rolls. Various classifications can be combined accordingly to give the rolls a clearer meaning, such as centrifugally cast high chromium cast iron work rolls for hot rolled strips.

Analyze what factors affect the production quality of cold rolls

The production quality of cold rolls is affected by the following factors:
1. The quality of the cold roll is closely related to the raw materials used. In general, the higher the hardness and the better the wear resistance of the roll material made of good steel, the longer the service life of the roll.


2. The precision and stability of production equipment will also affect its production quality. For example, the accuracy and stability of the roll bearing, transmission system, bending mechanism and other equipment of the rolling mill will affect its quality.
3. The production process will also affect its quality. For example, processes such as heat treatment, surface treatment, and maintenance of rolls can affect their performance.
4. The experience and skills of the operator will also affect the production quality of the cold rolled roll. Operators should have sufficient knowledge and skills, be able to operate the equipment correctly and master the process essentials to ensure its production quality.
5. Environmental factors such as cleanliness and temperature and humidity of the production environment will also affect the production quality of cold rolls. In the production process, the cleanliness and temperature and humidity of the production environment should be ensured to meet the requirements to avoid negative impact on it due to environmental problems.

Forged steel rolls

Through smelting, forging and heat treatment, the working layer of the forging steel roll body has uniform high hardness, high wear resistance and excellent anti-accident ability, and at the same time ensures that the roll neck and the core of the roll body have a certain strength and high toughness. This unique property of forged steel rolls makes it irreplaceable in cold rolling and non-ferrous rolling. According to the conditions of use, forged steel rolls can be divided into forged steel hot rolls and forged steel cold rolls, forged steel hot rolls are mainly used for hot rolling billet and section steel rough rolls, forged steel cold rolls are widely used in cold rolls. Forged steel cold rolled roll use requirements are high, the surface of the roll body must have high and uniform hardness, in order to ensure the dimensional accuracy and good surface quality of the cold rolled strip or steel plate, the roll body has a certain hardened layer depth, with high anti-accident ability, for this reason, the original structure of the roll is very strict, one is the pure metallurgical quality, the other is the uniformity of the structure. At present, China mainly uses the cold rolled roll material containing about 2% chromium, and the working layer above HS90 is about 10mm, and the newly developed Cr5 series cold rolled roll containing 5% chromium, the working layer above HS90 is more than 30mm, and the excellent performance of Cr 5 series cold rolled work roll in all aspects will gradually replace the traditional use of Cr 2 series cold roll, and become the development direction of cold rolled work roll.

What are rolls used for

Rolls are the main working parts and tools on the rolling mill that cause continuous plastic deformation of metal.

The roll is mainly composed of three parts: the roll body, the roll journal and the shaft head. The roll body is the middle part of the roll that actually participates in rolling the metal. It has a smooth cylindrical or grooved surface.

The variety and manufacturing process of rolls have evolved with the advancement of metallurgical technology and the evolution of rolling equipment. In the Middle Ages, low-strength gray cast iron rolls were used to roll soft non-ferrous metals. In the middle of the 18th century, Britain mastered the production technology of cold-hardened cast iron rolls for rolling steel plates. Advances in European steelmaking technology in the second half of the 19th century required the rolling of larger tonnage ingots, and neither grey cast iron nor chilled cast iron rolls were no longer strong.

How rolls work

Resistant to thermal cracking

Strength and thermal crack resistance are the main requirements for rough rolls, and the working rolls of small 20-high mills weigh only about 100 grams, while the back-up rolls of wide and heavy plate mills weigh more than 200 tons. When selecting rolls, first of all, according to the basic strength requirements of the rolling mill for the rolls, select the main material for safe bearing (various grades of cast iron, cast steel or forged steel, etc.).

hardness

The speed of the finishing roll is higher, and the final product of rolling must have a certain surface quality, which is mainly required for hardness and wear resistance. Then consider the wear resistance that the roll should have when it is used.

Impact-resistant

In addition, there are some special requirements for the roll, such as when the amount of pressure is large, the roll is required to have strong bite ability and good impact resistance;

Finish

When rolling thin gauge products, the rigidity, uniformity of microstructure, processing accuracy and surface finish of the roll are more stringent;

Cutting performance

When rolling steel with complex sections, it is also necessary to consider the cutting performance of the working layer of the roller body.

When selecting rolls, some performance requirements for rolls are often opposed to each other, and the purchase and maintenance costs of rolls are very expensive, so the technical and economic pros and cons should be fully weighed to decide whether to use cast or forged, alloy or non-alloy, single material or composite materials.