The metallurgical roll is a key component used in the rolling mill to make the metal produce plastic deformation, which plays an important role in the metallurgical industry, the following is a detailed introduction of it 2:
Structural composition
Roll body: is the working part of the roll, directly in contact with the rolled piece and produce plastic deformation, its surface can be smooth cylindrical shape or with rolling groove to adapt to different rolling needs.
Roll neck: located at both ends of the roll, used for installation in the bearing, through the bearing seat and the holding device to transfer the rolling force to the frame, to support the roll.
shaft head: At the drive end, the connecting shaft is connected with the gear seat, and the rotational torque of the motor is transferred to the roll to realize the rotation of the roll.
Classification mode
by process combination method
Integral roll: The outer shell, core and neck of the roll are cast or forged from a single material.
Metallurgical composite rolls: the outer part and core of the roll body (including the neck) are made of two or more materials, and the metallurgical bond between the two materials is used.
Combination roll: mainly set combination roll, which is assembled by different materials of roll sleeve and mandrel.
· According to forming method
· Casting roll: made by pouring molten steel or molten iron directly.
· Forging roll: Forged from ingot, semi-steel billet or clad cast iron.
· By structure
· Smooth roll: mainly used for rolling plate and strip.
· Grooved roll: mainly used for rolling profiles, wires and billets.
· By purpose
· Work roll: in direct contact with the rolling piece, generally a drive roll.
· Support roll: placed on the back or side of the work roll without direct contact with the rolled parts, mainly bearing bending load.
· As per rack
· Primary roll: used in the primary mill to roll ingots into billets.
· Rough roll: The rolled parts are rolled with large deformation in the rough rolling stage.
· Intermediate roll: used in the middle stage of the rolling process to further process the rolled parts.
· Finishing roll: used in the finishing rolling stage to carry out the final precise rolling of the rolled parts to ensure the dimensional accuracy and surface quality of the product.
· According to the variety of rolled wood
· Strip roll: used for rolling plate and strip.
· Rail and beam roll: used for rolling rail, steel beam, etc.
· Wire roll: used for rolling wire.
· Tube roll: used for rolling tubes.
· According to the condition of rolled parts
· Hot roll: used in hot rolling process, working in contact with high temperature rolled parts.
· Cold roll: used in cold rolling process to roll rolled parts at normal temperature.
Manufacturing process
Traditional craft
Integrated casting: with round sand box, dry sand production, the middle part of the cold, the bottom pouring form, but the toughness of the roll core is low.
Overflow casting: first pour the working part of the roll metal liquid, to be poured fully, then pour the core of the roll metal liquid, the center part of the unsolidified metal liquid, through the overflow trough discharge, can improve the toughness of the roll core.
Centrifugal casting: using vertical or horizontal casting, high metal liquid recovery rate, can save alloy materials, improve roll surface quality, improve roll strength and efficiency.
Forging: the small casting blank is forged after electroslag remelting, and then heat treatment and finishing. There is no problem of binding layer, but the manufacturing process is complicated and expensive.
New technology
Continuous casting composite technology: a forged steel core shaft is used, the surface is coated with flux, and the induction coil is preheated. The melted working layer metal is poured between the mandrel and the tundish with induction coil to form a bonding layer.
·Electroslag remelting surfacing welding technology: the electric current through the slag generated resistance heat melt metal, electroslag remelting instead of induction heating, the core shaft preheating and cleaning, promote the formation of bonding layer.
Powder metallurgy + hot isostatic pressing technology: The forged steel shaft welded with a steel container is placed in a container filled with metal powder, and the hot isostatic pressing is carried out under high temperature and high pressure to make a roll, which can form a good bonding layer, but is not suitable for manufacturing large rolls.
Common material
Cast iron: such as chilled cast iron, ductile cast iron, etc., has better wear resistance and corrosion resistance, the cost is relatively low.
Cast steel: high strength and toughness, can withstand greater rolling force and impact load, often used in large rolling mill roughing and rolling stand.
Forged steel: dense structure, good strength, toughness and wear resistance, suitable for cold rolling and hot rolling finishing stand with high roller performance requirements.
Tungsten carbide: with high hardness, high wear resistance, good thermal stability and corrosion resistance, it is often used in high-speed wire rolling mill where the wear resistance is very high.
Development trend
High performance: Develop roll materials and manufacturing processes with higher strength, hardness, wear resistance, heat resistance and fatigue resistance to meet the needs of high-speed, heavy-duty and high-precision rolling.
Compound: to further promote and improve the composite roll manufacturing technology, so that the outer layer and core of the roll can better play the performance advantages of different materials.
Intelligent: The use of advanced sensors and monitoring technology, real-time monitoring and analysis of the working status of the roll, to achieve intelligent maintenance and management of the roll.
