I. Product Introduction

Different types of rolling mills differ significantly in rolling process, load characteristics, speed range and operating environment, resulting in different technical requirements for bearings. NMT provides systematic bearing selection recommendations according to mill type and operating conditions.

 

Four-Row Tapered Roller Bearings: Can simultaneously withstand radial loads and bidirectional axial loads. Suitable for work rolls and backup rolls in hot and cold rolling mills. Axial clearance adjustable to适配 different mill rigidity requirements. In hot rolling conditions, open structures with cooling water protection seals are used; in cold rolling conditions, high precision grades and precision clearance settings are used.

 

Four-Row Cylindrical Roller Bearings: Primarily withstanding radial loads, with radial load capacity 3.5 to 4 times that of single-row bearings. Suitable for mill backup rolls and continuous caster segments. Cylindrical rollers and raceways form line contact, suitable for heavy loads and impact loads. Available in multiple structural types (FC, FCD, FCDP),适配 different size specifications and installation requirements.

 

Sendzimir Mill Bearings: Multi-row cylindrical roller bearings specifically designed for the compact space and high precision requirements of 20-high mills. Matched set precision requirements reaching P4 or higher, with section height differences and height differences between adjacent bearings controlled to high standards.

 

Sealing and Lubrication Supporting Products: Sealing and lubrication solutions configured according to operating conditions to ensure reliable bearing operation in specific environments.

 

II. Key Selection Parameters

NMT considers the following key parameters when selecting rolling mill bearings:

 

Load Conditions: Including radial load magnitude, presence of axial loads, load stability and impact frequency. Four-row tapered roller bearings are suitable for conditions with simultaneous radial and axial loads (such as work rolls); four-row cylindrical roller bearings are suitable for conditions primarily with radial loads (such as backup rolls).

 

Speed Range: Different mills have significantly different speeds. Sendzimir mills and high-speed wire rod mills operate at higher speeds, requiring bearings with high limiting speeds and good high-speed stability; hot roughing mills and continuous casters operate at lower speeds but require higher load capacity.

 

Temperature Conditions: In hot rolling conditions, bearing housing temperatures can reach 150-250°C, requiring bearing materials to be thermally stabilized and clearance settings to consider thermal expansion compensation. Cold rolling conditions have lower temperatures (60-120°C) but require higher precision.

 

Environmental Conditions: Water spray, scale, dust and other environmental factors impose different requirements on sealing systems. Conditions with severe water spray require combinations of labyrinth seals and contact rubber seals; conditions with significant dust can be supplemented with metal shields.

 

Precision Requirements: Processes with strict strip thickness tolerance control such as cold rolling, silicon steel rolling and non-ferrous metal rolling require bearing precision of P5 or higher. Hot roughing mills have relatively lower precision requirements but higher load capacity and impact resistance requirements.

 

III. Typical Application Scenarios and Selection Recommendations

Hot Roughing Mills: Operating characteristics include low speed, heavy loads, high temperature, large impact loads and severe water spray and scale environments. Selection recommendations: four-row tapered roller bearings for work rolls, four-row cylindrical roller bearings for backup rolls. Materials选用 thermally stabilized high-temperature bearing steel or GCr15 high-purity bearing steel. Sealing configuration using combined labyrinth and contact rubber seals. Clearance setting considering thermal expansion compensation from cold state to thermal equilibrium.

 

Hot Finishing Mills: Operating characteristics include relatively high speed, significant loads, high temperature and continuous water spray. Selection recommendations: high-precision four-row tapered roller bearings for work rolls, four-row cylindrical roller bearings for backup rolls. Precision controlled to P5 or higher. Sealing configuration using combined labyrinth and contact rubber seals. Grease选用 formulations with excellent water resistance.

 

Cold Rolling Mills: Operating characteristics include high speed, high precision, emulsion environment and significant loads. Selection recommendations: high-precision four-row tapered roller bearings for work rolls, precision P5 or higher. Four-row cylindrical roller bearings for backup rolls, precision P5 or higher. Sealing configuration using contact rubber seals with HNBR material for emulsion corrosion resistance. Grease选用 formulations with excellent anti-emulsification properties. Clearance setting considering thermal equilibrium at high-speed operation.

 

Continuous Caster Segments: Operating characteristics include very low speed, heavy loads, continuous water spray and scale environment. Selection recommendations: four-row cylindrical roller bearings. Sealing configuration using combined labyrinth and contact rubber seals with FKM or HNBR for water and steam resistance. Grease选用 formulations with excellent water resistance, with internal bearing channel design ensuring grease supply at very low speeds.

 

Sendzimir 20-High Mills: Operating characteristics include compact space, high speed, high precision and intermittent alternating use. Selection recommendations: multi-row cylindrical roller bearings (backing bearings). Precision requirement P4 or higher. Section height differences and height differences between adjacent bearings within matched sets controlled to high standards. Oil-mist or oil-air lubrication.

 

Wire Rod and Bar Mills: Operating characteristics include high speed, frequent start-stop and impact loads. Selection recommendations: double-row angular contact ball bearings or deep groove ball bearings for finishing stands. Four-row tapered roller bearings or spherical roller bearings for roughing/intermediate stands. Cage materials and lubrication methods selected according to speed and impact loads.

 

IV. Quality Assurance

Data Support for Selection: Based on understanding of mill operating conditions and accumulated actual application data, NMT provides data support for selection recommendations. The selection process considers load spectrum (not a single load value but load distribution throughout the rolling process), speed spectrum (speed variation range and proportion) and temperature conditions (effect of operating temperature on material fatigue strength).

 

Precise Calculation of Clearance Setting: NMT calculates and recommends optimal cold installation clearance values based on bearing operating temperature, speed and load conditions. For four-row tapered roller bearings, clearance is achieved by adjusting spacer ring thickness between inner rings; for four-row cylindrical roller bearings, clearance is determined by the配合 between the bearing and the roll neck and housing. Clearance setting solutions are based on “target clearance at operating temperature” reversed to “cold installation clearance.”

 

Condition Adaptation of Seal Configuration: NMT recommends seal solution types and materials according to water pressure, spray pattern, dust concentration and temperature conditions. Labyrinth seal gap dimensions are determined according to bearing size and water pressure conditions; contact seal lip compression is determined according to temperature and speed conditions.

 

Matching of Lubrication Solutions: NMT recommends grease base oil viscosity grades and additive formulations according to bearing type, load, speed and temperature conditions. Base oil viscosity ranges from ISO VG 150 to ISO VG 1000. Proportions of extreme-pressure anti-wear additives, rust inhibitors and water-resistant additives are adjusted according to operating conditions.

 

V. Product Range

NMT provides the following selection solutions for different mill types:

 

Hot Roughing Mill Solution: Four-row tapered roller bearings (work rolls) + four-row cylindrical roller bearings (backup rolls). High-temperature bearing steel material + thermal stabilization treatment. Labyrinth + contact combined seals. High-temperature water-resistant grease. Clearance setting with thermal expansion compensation.

 

Hot Finishing Mill Solution: Four-row tapered roller bearings (work rolls) + four-row cylindrical roller bearings (backup rolls). Precision P5 or higher. Labyrinth + contact combined seals. Water-resistant grease. Precision clearance setting.

 

Cold Rolling Mill Solution: High-precision four-row tapered roller bearings (work rolls) + high-precision four-row cylindrical roller bearings (backup rolls). Precision P5 or higher. Contact HNBR seals. Anti-emulsification grease. High-speed thermal equilibrium clearance setting.

 

Continuous Caster Solution: Four-row cylindrical roller bearings. FKM/HNBR seals. Water-resistant grease. Low-speed heavy-load clearance setting.

 

Sendzimir Mill Solution: Multi-row cylindrical roller bearings. Precision P4 or higher. Oil-mist/oil-air lubrication. Compact-space high-load design.

 

VI. Brand Strength

NMT has accumulated systematic application experience in rolling mill bearing selection.

 

Understanding of Operating Conditions: NMT has systematic understanding of the operating characteristics of different mill types. Familiar with the load characteristics, speed ranges, temperature conditions and environmental characteristics of hot rolling, cold rolling, continuous casting, Sendzimir, wire rod and bar mills, and able to consider these factors comprehensively during selection.

 

Selection Methodology: NMT has established a selection process based on mill parameters (mill type, rolling force, speed, temperature, coolant conditions, etc.). The selection process considers bearing dynamic load rating, static load rating, limiting speed and modified life to ensure selection results meet user design life and reliability requirements.

 

Clearance Calculation Capability: NMT has accumulated clearance setting data for different mill operating conditions, enabling provision of cold installation clearance recommendations at the selection stage.

 

Sealing and Lubrication Selection Experience: NMT's experience in selecting sealing and lubrication solutions according to operating conditions helps users obtain complete bearing configuration solutions at the selection stage.

 

VII. Global Collaboration

NMT provides rolling mill bearing selection consultation and technical support services to steel mills, non-ferrous metal processors and metallurgical equipment manufacturers worldwide.

 

Service Reach: Selection services cover various mill types including hot rolling, cold rolling, continuous casting, Sendzimir, wire rod and bar mills, as well as non-ferrous metal rolling equipment for aluminum, copper and other materials.

 

Collaboration Model: In the project preliminary stage, NMT can provide preliminary selection recommendations based on user-provided mill parameters. In the detailed design stage, NMT can provide complete selection documentation including bearing installation dimensions, clearance setting values, seal configuration solutions and lubrication solutions. In the equipment operation stage, NMT can review and optimize selection solutions based on actual operating data.

 

Technical Support: NMT can provide selection training, installation guidance and operational assessment services according to user needs. Selection training covers mill parameter collection methods, selection calculation procedures, clearance setting methods and other content.