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LB/MLB SERIES

LB/MLB SERIES
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LB/MLB SERIES LB/MLB SERIES LARGE BORE/MATCHED LARGE BORE HYSTERESIS 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 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. Fig.1 : LB Series Large Bore Hysteresis Brake 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. Unless otherwise specified, all brakes are matched at 100 rpm. Regular Brakes Matched Brakes Brake Power Supply Brake Power Supply In tension control applications that have multiple webs or multiple strands, it is very desirable to match the tension of each web or strand. This is most commonly attained by using a closed-loop servo control system which controls current to a braking device through the use of dancer arms, follower arms and in-line tension transducers. The problem with such systems is that each web or strand must be individually controlled, increasing the cost Power Supply Power Supply Brake Brake 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 © 2019 MAGTROL | Due to continual product development, Magtrol reserves the right to modify specifications without forewarning.

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LB/MLB series H MAGTROLPRINCIPLES OF HYSTERESISOVERVIEW 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 rotor — magnetically restrained, <Dra9 Cup) providing a braking action between the pole...

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LB/MLB series H MAGTROLSPECIFICATIONSBRAKE RATINGS BRAKE MODEL a) Higher speeds, up to 8000 rpm, are available on special basis. b) Kinetic power ratings are maximum values based on limiting coil and/or bearing temperature to approximately 100 °C, and should not be exceeded. Actual values in service may vary ±50% depending on mounting, ventilation, ambient temperature, etc. * To prevent damage to the power supply from inductive kickback, connect a diode rated at greater than or equal to the power supply’s output voltage and current across the brake leads. Connect the cathode to the positive...

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LB/MLB SERIES OPERATING CONSIDERATIONS At the standard bore diameters, actual brake torque at rated current will normally exceed the minimum guaranteed values. Larger bore diameters can be provided, however, reductions in performance will result as bore diameters are increased. Any modification to a Large Bore Brake should be reviewed in detail with Magtrol before ordering. BRAKE OPTIONS TORQUE CURRENT CURVES Nominal performance characteristic curves similar to that shown above will be provided by Magtrol, upon request. Precise calibration curves for individual brakes can be provided, but...

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