Archive for category: Knowledge

Pressure Roller Bearings in Sinter Plants: Critical Components for Pallet Car Operations

In industrial settings such as sinter plants, where heavy machinery operates under extreme conditions, pressure roller bearings play a pivotal role in ensuring reliability, efficiency, and longevity of equipment. This article explores the application of pressure roller bearings in sinter plants, with a focus on their critical function in pallet cars, which are integral to the sintering process.

1. Understanding Pressure Roller Bearings
Pressure roller bearings, also known as tapered roller bearings or cylindrical roller bearings, are designed to handle both radial and axial loads. Their unique structure-comprising an inner ring, outer ring, tapered rollers, and a cage—enables them to withstand high-pressure conditions while minimizing friction. These bearings are widely used in heavy-duty applications, including mining, steel production, and material handling systems like those in sinter plants.

2. Role of Pallet Cars in Sinter Plants
In a sinter plant, pallet cars are specialized vehicles that transport raw materials (e.g., iron ore fines, coke, and fluxes) through the sintering process. The sintering machine consists of a continuous loop of pallet cars that move along a track, carrying the raw mix through ignition furnaces, cooling zones, and discharge points. During this process, the materials are fused at high temperatures (up to 1,300°C) to form sintered agglomerates, a crucial feedstock for blast furnaces.

Pallet cars operate in harsh environments characterized by:
– Extreme heat from sintering furnaces.
– Heavy loads due to the weight of materials and equipment.
– Dust and abrasive particles generated during material handling.
– Continuous vibration from the movement of the sintering machine.

3. Application of Pressure Roller Bearings in Pallet Cars
Pressure roller bearings are indispensable for the smooth operation of pallet cars. They are typically installed in the following critical areas:
– Wheel assemblies: Bearings support the wheels of pallet cars, enabling them to move smoothly along the track under heavy loads.
– Drive mechanisms: Bearings reduce friction in gearboxes and drive shafts, ensuring efficient power transmission.
– Guide rollers: These bearings maintain alignment and stability as pallet cars navigate curves and inclines.

Key design considerations for pressure roller bearings in sinter plants include:
– High-temperature resistance: Bearings must retain structural integrity and lubrication properties even when exposed to radiant heat from sintering furnaces. Special heat-resistant alloys or ceramic coatings are often employed.
– Dust and contamination protection: Sealed bearings or labyrinth seals prevent ingress of abrasive sinter dust, which can accelerate wear.
– Load capacity: Bearings must support the combined weight of the pallet car, sinter mix, and thermal stresses. Reinforced cages and larger roller diameters are common solutions.
– Lubrication systems: Automatic lubrication systems or high-temperature greases are used to ensure continuous performance under demanding conditions.

4. Challenges and Solutions
The harsh operating environment of sinter plants poses significant challenges for pressure roller bearings:
– Thermal expansion: Temperature fluctuations can cause bearing components to expand or contract, affecting clearance and alignment. Precision engineering and thermal compensation designs mitigate this issue.
– Abrasive wear: Sinter dust infiltrating bearings leads to premature failure. Advanced sealing technologies, such as multi-layered seals or air-purge systems, are critical.
– Fatigue failure: Cyclic loading from continuous operation necessitates bearings with high dynamic load ratings and fatigue-resistant materials like case-hardened steel.

5. Maintenance and Monitoring
Proactive maintenance is essential to maximize bearing lifespan in pallet cars:
– Regular inspections: Visual checks for wear, misalignment, or lubrication deficiencies.
– Vibration analysis: Detects early signs of bearing damage, such as spalling or brinelling.
– Thermal monitoring: Infrared cameras identify overheating bearings caused by inadequate lubrication or excessive friction.
– Lubrication management: Scheduled relubrication with high-temperature greases reduces wear.

6. Case Study: Enhancing Pallet Car Reliability
In a modern sinter plant, upgrading to advanced pressure roller bearings with hybrid ceramic rollers (steel races with ceramic rolling elements) reduced downtime by 30%. The ceramic components offered superior heat resistance and reduced friction, while integrated sensors enabled real-time condition monitoring. This innovation improved pallet car efficiency and extended maintenance intervals.

7. Conclusion
Pressure roller bearings are unsung heroes in sinter plants, enabling pallet cars to operate reliably under extreme conditions. Their design, material selection, and maintenance protocols directly impact the productivity and cost-effectiveness of the sintering process. As sintering technology evolves, advancements in bearing materials (e.g., graphene-enhanced lubricants, smart bearings with IoT connectivity) promise to further enhance performance in this critical industrial application.

By prioritizing robust bearing solutions, sinter plants can achieve higher throughput, reduced energy consumption, and lower operational costs—key factors in the competitive steel manufacturing industry.

Introduction

Spring bush bearings, also known as spring roller bearings, find widespread use in various applications. One of the most typical areas of application is the steel industry. These bearings are employed in various components, including:

1. Rollers in Steel Mills: In rolling mills, spring bush bearings support the rollers that shape and process steel sheets.
2. Continuous Casting Machines: Spring bush bearings are used for supporting the guide rollers and directing rollers in continuous casting machines.

3. Furnace Equipment: Inside furnaces or refining equipment, spring bush bearings are utilized for the rollers that handle hot materials.

   Construction and Components

   The construction of spring bush bearings is relatively straightforward. They consist of three main components:

   1. Inner Ring: The inner ring provides the mounting surface for the bearing.
   2. Rolling Elements: These typically include cylindrical rollers with a retaining cage. The rolling elements facilitate smooth rotation.
   3. Outer Ring: The outer ring encloses the entire assembly and provides stability.

   These basic elements can be assembled to create various types of bearings, depending on specific requirements. Whether the application involves split bearing housings, high-temperature operations, or axial load transmission, spring bush bearings can adapt. They handle impact loads and minor misalignments with ease, making them versatile even when multiple challenges arise simultaneously. Additionally, these bearings exhibit excellent wear resistance.

   

   Elasticity and Tolerance

   One notable feature of spring bush bearings is their inherent elasticity. The slight clearance between the inner and outer rings allows them to maintain functionality even under conditions like bending deformation. This property makes them particularly suitable for continuous casting machines and high-temperature transfer equipment.

   Advantages of Spring Bush Bearings

   1. Robust Design: Spring bush bearings share a similar height profile with needle roller bearings but offer greater durability. They can withstand temperature variations, contamination, and inadequate lubrication.
   2. Tolerance to Deviations: These bearings tolerate deviations and inclinations, making them ideal for challenging environments.

   3. Application Range: Spring bush bearings find applications beyond the steel industry. They are also used in mining, cement, and other heavy-duty sectors.

The pressure roller bearings are mainly used in the continuous furnaces of sintering plants. They are massive bearings ready to be fixed. They are used with heavy loads and where the rotation reverses continuously at low speed.
The outer ring shows three entire borders, one section and one outer surface which is highly resistant to wear.
The inner ring is made of two parts, each one has an entire border expressly developed in order to bear high axial thrusts, in addition to radial loads.
Pressure roller bearings do not need maintenance.
The outer ring and the inner ring are manufactured in GCr18Mo steel.
Hardness 60-2 HRC.
In order to increase the resistance to wear, pressure roller bearings usually undergo bainitic temper treatment up to 250° C, named S2.
The sealing system foresees the presence of Viton O-rings, which are inserted in the proper grooves on the inner ring. The seals allow the bearing to be disassembled, they prevent the entrance of contaminating agents and in the meantime, the leakage of lubricant.

Code	d	D	B	Load ratings
				C (KN)	Co (KN)
PRB88x170x95	88	170	95	384	908
PRB93x170x95	93	170	95	384	908
PRB93x171x95	93	171	95	384	908
PRB110x200x90	110	200	90	414	841
PRB110x210x110	110	210	110	479	942
PRB110x300x87/133	110	300	87/133	604	1022
PRB120x190x130	120	190	130	580	1570
PRB120x210x113.8	120	210	113.8	584	1268
PRB120x210x114	120	210	114	584	1268
PRB128.665x210x101.6	128.665	210	101.6	393	1132
PRB128.665x210x114	128.665	210	114	463	1395
PRB130x210x132	130	210	132	529	1659
PRB130x250x132	130	250	132	899	1664
PRB140x250x114	140	250	114	769	1601
PRB140x250x130	140	250	130	899	1957

Cam followers (stud-type track rollers) are designed to run on tracks and to be used in cam drives, conveyor systems, etc. They are based on either needle or cylindrical roller bearings. Instead of an inner ring, they have a threaded solid stud (pin).

Features and benefits:

1. Accommodate high radial loads
2. Accommodate axial loads
3. Long service life
4. Easy to mount

NUKR35, NUKR40, NUKR47, NUKR52, NUKR62, NUKR72, NUKR80, NUKR85, NUKR90, NUKR100, NUKR110

 

The slewing drive is a complete system assembly that can be easily installed and integrated into existing system programs.

It is composed of ball slewing bearing or cylindrical roller slewing bearing, worm, shell and other parts that can bear axial, radial and overturning moments at the same time. The worm is driven by a hydraulic motor or motor to drive the slewing bearing to rotate. The surface of the housing is spray-coated and fully enclosed with seals to protect the slewing drive from contamination, damage and grease loss.

These components are assembled together to avoid customers installing various mating components, and we can also provide a variety of size standards.

The outstanding advantages of the slewing drive are as follows:
• The design is very compact, suitable for installation of mechanical equipment with limited space.

• Very high load carrying capacity in a very compact design.

• long lasting.

• Low maintenance costs.

• Cast housing protects internal parts.

Slewing drives are used worldwide for:
• Vehicle and crane systems.

• Rotation of attachments such as excavators, hydraulic tongs and forklifts.

• Facility management (automated systems).

• Loading and unloading equipment.

• Positioning Systems.

The rotary motion of the slewing drive is driven by a hydraulic motor or an electric motor. It is easy to find a matching hydraulic motor in the market, and it also conforms to industry standards, which can save a lot of time. For the motors, however, some device adapters are also required.

The housing of the slewing drive is a cast part and can be dimensioned according to customer requirements. The closed housing protects the swing system from contamination, damage and grease loss, ensuring smoother operation and longer life of the swing drive.

Additionally, labyrinth seals mounted on the housing structure protect the interior of the assembly from contamination if the swing drive is used in wet or dirty environments. Because the performance and reliability of the slewing drive depends to a large extent on the internal stability. It is worth noting that high-pressure water guns cannot be used to clean the swing drive, as the pressurized water will penetrate the seal and enter the inside of the swing drive, which will greatly reduce the service life.

Slewing drives can be used in temperatures ranging from -20°C to 70°C.

Proper and regular lubrication is required to ensure stable operation and long service life of the slewing drive. Grease is conducive to the better functioning of the rotary drive, reducing wear, reducing noise during operation, extending service life and reducing heat generation.

Periodically lubricate with a grease compatible with the seal material, depending on the frequency of use and ambient operating conditions.

It is best to fill the slewing drive with the same lubricating oil that was originally used. If you wish to use another type of grease, you must verify that the grease is compatible with the originally used grease. In addition, regular relubrication is recommended during operation and after extended periods of non-use or cleaning.

Grease that has been aged but not used should be replaced if it has not been used after three years. Also, greases must not be mixed with different thickeners and base oils.