Direct Drive DC Torque Motors
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Data Publication Direct Drive DC Torque Motors The Direct Drive DC torque motor is a servo actuator which can be directly attached to the load it drives. It has a permanent magnet (PM) field and a wound armature which act together to convert electrical power to torque. This torque can then be utilized in positioning or speed control systems. In general, torque motors are deigned for three different types of operation: • High stall torque (“stand-still” operation) for positioning systems • High torque at low speeds for speed control systems, and • Optimum torque at high speed for positioning, rate, or tensioning systems. Direct drive torque motors are particularly suited for servo system applications where it is desirable to minimize size, weight, power and response time, and to maximize rate and position accuracies. Frameless motors range from 28.7mm (1.13in) OD weighing 1.4 ounces (.0875 lbs) to a 4067 N-m (3000 lb-ft) unit with a 1067mm (42in) OD and a 660.4mm (26in) open bore ID. Housed motors range from a one inch cube design with 0.049 N-m (7 oz-in) peak torque to any of the frameless motors housed to customer specifications with integral DC tachometers, resolvers, encoders and shaft configur

Direct Drive DC Torque Motors INTRODUCTION Advantages of Direct Drive DC Torque Motors High Torque-to-Inertia Ratio at the Load Reliability and Long Life A direct drive motor provides the highest practical torqueto-inertia ratio where it counts—at the load. In a geared system, reflected output torque is proportional to the gear reduction while reflected output inertia is proportional to the square of the gear reduction. Thus, the torque-to-inertia ratio in a geared system is less than that of a direct drive system by a factor equal to the gear-train ratio. The higher torque-to-inertia ratio...

System Performance Characteristics The same features which give torque motors an advantage over other types of servo actuators also allow the designer to obtain the following system performance characteristics. High Servo Stiffness The direct-drive torque motor is coupled directly to the load, thus eliminating gears and backlash errors. The resulting high coupling stiffness and associated high mechanical resonance frequency yield high servo stiffness. Fast Response The low electrical time constant of torque motors allows torque to develop very rapidly when voltage is applied. This fast...

Direct Drive DC Torque Motors INTRODUCTION PERMANENT MAGNET FIELD ASSEMBLY ARMATURE LAMINATION STACK STEPPED SHAFT MOUNTING BRUSH RING ASSEMBLY S KEEPER RING ALNICO DESIGN COMMUTATOR Figure 2 - Frameless Alnico torque motor, showing hole for axial-shaft mounting. BRUSH RING ASSEMBLY ARMATURE ASSEMBLY (ROTOR) SILVER GRAPHITE BRUSHES FIELD ASSEMBLY (STATOR) SAMARIUM COBALT MAGNETS RARE EARTH DESIGN Figure 4 Alnico and rare earth magnet designs Figure 3 - Frameless rare earth torque motor. KOLLMORGEN • Radford, Virginia • 1-800-77 SERV

Direct Drive DC Torque Motors INTRODUCTION Magnet Material The motors are manufactured with one of two magnet materials: Alnico or rare earth (Samarium Cobalt and Neodymium-Iron-Boron). Model numbers preceded by “T’, “NT”, or “OT” have Alnico magnets and models preceded by “QT” have rare earth magnets. These magnet materials have different characteristics which determine their suitability for various applications. Performance: A major advantage of rare earth magnet motors is stability of magnetic characteristics in overcurrent conditions. In Alnico magnet motors, exceeding the rated current...

FRAMELESS TORQUER SELECTION GUIDE Model Number Note: Metric conversions provided for reference only. Continued on adjacent page. KOLLMORGEN • Radford, Virginia • 1-800-77 SERVO

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- TABLE OF STANDARD OPTIONS - These standard options allow our customers to modify existing catalog motors to achieve the features as described below. Please consult factory for application information. Kollmorgen enjoys a reputation of excellence based on constant endeavors to update products. Information in this brochure is subject to change. E-mail: servo if/ kollmorgen.com Internet: http://www.kollmorgen.com Fax:1-540-731-0847 Radford, VA USA • 1-800-77 SERVO