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Large Bore and Matched Large Bore Brakes LB / MLB Series

Large Bore and Matched Large Bore Brakes LB / MLB Series
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Large Bore and Matched Large Bore Brakes LB / MLB Series - 1

LB/MLB Data Sheet LB Large Bore Brakes and MLB Matched Brakes FEATURES • • • • • • • • • • Torque up to 12 N·m Speed up to 3000 rpm (higher speeds available) Power up to 1200 W No shaft or bearings: ideal for feed-through applications Torque independent of speed Long, maintenance-free life Operational smoothness Superior torque repeatability Broad speed range Excellent environmental stability Pole/Case Assembly DESCRIPTION For many years Magtrol has designed hysteresis brakes with large bores, and without a shaft or bearings. These uniquely designed brakes contain a large inside diameter to accommodate wire fed directly through the brake, while the rotor mounted to a tape supply reel, provides the required tension. Magtrol Large Bore Brakes consist of two primary parts: a pole/case assembly and a rotor. The pole/case assembly is usually mounted in a stationary position within the machine, while the rotor is shaft-mounted concentrically within the pole/case assembly. As with all of Magtrol’s hysteresis devices, LB/MLB Series Brakes operate without the use of magnetic particles or friction components. This provides absolute smoothness, superior torque repeatability, quiet operation and a long, maintenancefree life. MATCHED BRAKES In tension control applications that have multiple webs or multiple strands, it is very desirable to match the tension of each web or Matched Brakes Regular Brakes strand. This is most Brake Brake commonly attained Power Supply Transducer Power Supply Transducer by using a closedloop servo control Brake Brake system which controls current to Power Supply Transducer Brake a braking device Brake Brake through the use of dancer arms, Power Supply Transducer Brake follower arms and 1 in-line tension transducers. The problem with such systems is that each web or strand must be individually controlled, increasing the cost and complicating the system with multiple sensors and power supplies. To solve this problem, Magtrol developed a system to assure that every brake of a given model designation will be matched—at a predetermined torque and current point—to other brakes of the same model designation. Regardless of material and manufacturing tolerances, each brake is matched at the selected match point to within a tolerance of ±1%. The maximum deviation in torque from brake to brake at any point along their torque/current curve (from 0 torque up to the selected matched torque point) is less than ±4% of the selected matched torque value. With this level of matching, a system with multiple tension rollers would provide tension consistency within ±1% if set at the matched point with all brakes receiving the same current. The matched point can be any value between 50% and 100% of rated torque, which allows the brakes to be optimized for specific applications. Helical wrapping, braiding and other feed-through applications—used in machines for manufacturing cable, wire, fiber optic cable, rope and tape Flyer control in winding operations

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Large Bore and Matched Large Bore Brakes LB / MLB Series - 2

Hysteresis Principles PRINCIPLES OF HYSTERESIS Overview The hysteresis effect in magnetism is applied to torque control by the use of two basic components –a reticulated pole structure and a specialty steel rotor/shaft assembly–fastened together but not in physical contact. Until the field coil is energized, the drag cup can spin freely on the ball bearings. When a magnetizing force from either a field coil or magnet is applied to the pole structure, the air gap becomes a flux field. The rotor is magnetically restrained, providing a ROTOR braking action between (Drag Cup) the pole structure...

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Large Bore and Matched Large Bore Brakes LB / MLB Series - 3

RATINGS Large Bore Brake Model LB-250M-2 LB-450M-2 LB-750M-2 LB-1750M-2 * Higher speeds, up to 8000 rpm, are available on special basis. ** Kinetic power ratings are maximum values based on limiting coil and/or bearing temperature to approximately 100 ºC, and should not be exceeded. Actual values in service may vary ±50% depending on mounting, ventilation, ambient temperature, etc. N (4* FHCS) Mounting Holes equally spaced FRONT VIEW (Rotor) Large Bore Brake Model LB-250M-2 LB-450M-2 LB-750M-2 LB-1750M-2 Mounting Holes equally spaced SIDE VIEW REAR VIEW (Pole/Case Assembly) * Slightly...

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Large Bore and Matched Large Bore Brakes LB / MLB Series - 4

SPECIAL DESIGNS POWER SUPPLIES Since 1953, Magtrol has created literally thousands of special and modified brake designs to help solve specific application problems for our customers. For optimum torque stability, Magtrol offers four different power supplies for its Hysteresis Brakes and Clutches: Model 5200 Power Supply Common Modifications • • • • • • • • Non-Standard Coil Voltages Special Shaft Configurations: keyways, flats, holes and hollow Dust Covers Speed Pickups Special Mounting Configurations Non-Standard Lead: material, lengths, location Higher Torque Devices High Speed Units...

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