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MDA Technologies 5/2015

MDA Technologies 5/2015

MACHINE ELEMENTS Steel

MACHINE ELEMENTS Steel is produced from pig iron in converters. Slow swiveling motions under heavy weights and shock loads require the bearings to have an exceptional static load carrying capacity. Alignment errors and design deformations must be compensated. Here, Schaeffler develops customized FAG spherical roller bearings with outside diameters of up to 1750 mm to meet the challenges in converters for the long term. Long-life ELGES plain bearings are used to support the vessel in a trunnion ring that is itself supported in housings with a swivel facility for pouring. The main gears in the gearboxes are supported by FAG deep groove ball bearings or cylindrical roller bearings. The comprehensive services Schaeffler provides range from the installation of bearings and housings to integrated monitoring systems. The liquid steel is cast continuously through an ingot mold in continuous casting plants. In its Continuous Caster Bearing (CoCaB) program, Schaeffler combines all bearing solutions that are specially tailored to the requirements of these facilities. Recently, the CoCaB program was extended to include ELGES large size spherical plain bearings with plastic sliding plates. The glass fiber reinforced plastic contains PTFE, and the bearings feature a very long service life, just like bearings with the tried and tested ELGOGLIDE sliding layer. Reliable top performers for metal forming In hot rolling processes, both flat products such as heavy plates or hot strips and long products such as sectional steel or bar stock are rolled. In cold rolling, cold strips are usually formed without heating them beforehand. Schaeffler offers powerful rolling bearings and optimized services for the extraordinary requirements in rolling mills. Application-specific developments are 02 In the Mancrodur high-performance steel with carbonitriding heat treatment, the addition of nitrogen produces ball-shaped carbonitrides, resulting in a fine, even microstructure. The following are visible in the material structure: (1) Coarse carbides, (2) Fine carbonitrides made in close cooperation with machine manufacturers and operators. Multi-row tapered roller bearings for rolling mills Schaeffler’s new high-performance steel Mancrodur, in combination with the carbonitriding heat treatment process, results in a significant extension of the service life of multi-row FAG tapered roller bearings. These feature as the Performance series and are the new standard for rolling mills. Bearings in rolling mills are subjected to high loads due to forces, speed and shocks in extreme ambient conditions. With the Mancrodur high-performance steel with carbonitriding heat treatment, nitrogen as well as carbon are added to the bearing surface, which provides the bearings with a greater surface hardness and wear resistance. The addition of nitrogen produces ball-shaped carbonitrides, resulting in a fine and even microstructure. This provides the tapered roller bearings with greater surface hardness and wear resistance. 01 Double-row and four-row FAG tapered roller bearings from the Performance series are used as roller bearings in rolling mills For over-rolled particles and mixed friction (boundary lubrication conditions), a significantly extended service life is achieved due to wear resistance and an improved microstructure. In an application, this leads to much higher plant efficiency. Integrated monitoring system for trunnion bearings One of the main requirements in the steel processing industry is the greatest possible availability of central production facilities. Particularly for bottleneck units such as converters in oxygen steel plants, downtimes can cost plant operators up to millions of euros. Schaeffler offers a solution with its new, integrated online monitoring system for trunnion bearings and gearboxes in converters. Schaeffler has integrated innovative monitoring systems such as acoustic emission measurements, oil particle analysis by means of the FAG Wear Debris Check as well as a check of the lubricating grease condition using the FAG GreaseCheck into a unique condition monitoring system. This makes it possible to schedule maintenance work and avoid expensive, unplanned plant downtimes due to bearing damage. Certified experts provide customers with support for data analysis and recommended actions. The principle of acoustic emission measurement is ideal for slowly rotating trunnion MDA Technologies 5/2015 17

MACHINE ELEMENTS 99 Failure probability 90 50 10 5 Standard material: Case hardened steel Mancrodur® carbonitrided 03 Increased performance due to Mancrodur 04 The FAG Wear Debris Check measures the number of particles in the oil and allows the transmission of parameters to superordinate monitoring systems as well as the entry and analysis of particle concentration, classified by size and material 1 10 100 1000 10000 Time [h] bearings such as those used in converters. Here, the usual vibration measurement cannot be used reliably because the speed is too low and the amount of energy released when damage in a rolling bearing is over-rolled is not sufficient for analyzable structure-borne sound measurements. Equally, processes that are too short may reduce the measurement time so much that the resolution is too low. Acoustic emission measurement, on the other hand, makes use of the effect that plastic deformation or fractures are the result of loads applied to material beyond the elastic limit. This defect leads to a concentration of stresses, to crack formation and ultimately to a sudden reduction of the stress in the material. This brief process generates an acoustic emission event that moves away from the source as an ultrasound wave and can be measured. Signs of wear on the bearings or gear teeth in gearboxes become visible long before an impending failure in the form of metal abrasion. When this abrasion is measured and monitored, damage to gearboxes with recirculating oil lubrication as well as plain bearings can be detected at an early stage. The FAG Wear Debris Check measures the number of particles in the oil and allows the transmission of key indicators to superordinate monitoring systems as well as the entry and analysis of particle concentration, classified by size and material. More than half of all rolling bearing failures can be attributed directly to lubrication. The FAG GreaseCheck lubricating grease sensor and the related electronic analyzing system allow the detection of condition changes in the grease of the FAG Arcanol series during operation, long before damage occurs in the rolling bearing. This makes it possible to schedule lubricating grease replacement and extend the service life of the rolling bearing. The new FAG spheroidal graphite cast iron housings for converter bearings already include bores for grease quality measurements in addition to measuring points for acoustic emission sensors. Besides the total number of more than 60 ascertainable parameters, it is also necessary to enter he process parameters as part of the monitoring strategy. FAG ProCheck monitors representative parameters and processes them accordingly for plant visualization. The alarm function of FAG ProCheck reports malfunctions and defects. Schaeffler service engineers can use remote access to perform evaluations and analyses with the necessary level of detail and make recommendations for required actions. Photographs: Schaeffler Technologies www.schaeffler.com 05 The liquid steel is cast continuously through an ingot mold in continuous casting plants. In its Continuous Caster Bearing (CoCaB) program, Schaeffler combines all bearing solutions that are specially tailored to the requirements of these facilities About Company name: Schaeffler Technologies Brands: INA, LuK and FAG Headquarters: Herzogenaurach, Germany Turnover: € 12,1 billion Employees: around 84,000 Products: Roller bearings and plain bearings, linear and direct drive technology 18 MDA Technologies 5/2015

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