Motors are highly specialized, but their level of specialization pales in comparison to mechanical actuators. Actuators can be rotary or linear, and offer solutions for tight size constraints, backlash, vibration, environmental, self-locking, explosion proof and the list goes on. Yet all of these characteristics can be important to an application's needs, and the actuator's ability to meet these needs drives the appropriate mechanical actuator choice in any particular design.
Sometimes the combination of motor and actuator, and the way they are combined, has everything to do with the success of the machine. Suppliers know this and are integrating motors with actuators into standard products, creating a new breed of products that deliver improved, repeatable performance. Today's motor-actuator combinations are designed to meet a wide range of technical and cost goals. Usually in compact and affordable packages, these new products are designed to be effectively and efficiently applied to customer's particular needs.
ACTUATOR-CONTROLLER
The MTR-DCI servo actuator from Festo has been designed with integrated power electronics and controller to simplify positioning applications. The MTR-DCI combines a dc motor with integral rotary gearbox to provide torques ranging from 0.17 to 12.3 Nm and respective top speeds from 481 to 156 RPM. The actuator reduces space requirements in the control cabinet because the controller is integrated into the motor. Wiring is also reduced with a single source of power and no wiring required between controller and motor. Required I/O connections are made directly to a multi-pin connector on the unit. Menu-driven operation and the optional LCD display (resolution of 128 × 64) simplifies programming. The complete commissioning process can be performed by using simple teach-in functions. The new MTR-DCI offers a variety of positioning functions including 16 positioning memory records (including homing), constant acceleration and deceleration, and a homing mode using a switching signal or mechanical stop.
DUAL-FORCER LINEAR MOTOR
Equipped with two independent load-positioning forcers on a single rail, ServoTube motors from Copley Controls can position two items simultaneously to improve throughput in pick and place applications. A ServoTube motor's drive force is produced by the interaction between the forcer's electrically powered magnetic field and the thrust rod's permanent magnet field. The thrust rod's permanent magnets are enclosed in a stainless steel tube; electromagnetic drive coils are contained within the forcer. The motor's two forcers move independently and in opposite directions when required. Each forcer's drive coil is energized by its own Xenus micro controller. ServoTube's direct magnetic drive achieves fast response by eliminating the friction and inertia of rotary-to-linear conversion mechanisms. Each forcer develops up to 80 lb peak drive force, and has a 3 m/sec peak speed. A patented magnetic design enables a solid-state position sensor to achieve 12 microns repeatability replacing feedback encoders. ServoTube motors are food-safe and meet IP67 wash-down specifications.
COMPACT ELECTROMECHANICAL LINEAR ACTUATORS
The MINILINE® family of linear actuators from Concise Motion has a hollow-rotor design which allows the piston rod to “telescope” through the axis of the motor. This makes it possible to have a retracted length which is less than twice the effective stroke including internal limit switches and planetary gearing. Unlike conventional designs with right-angle or parallel motors, the coaxial design has a very small cross-section as well. The stainless-steel case is washdown rated for use in harsh environments. The company claims the MINILINE® is the most compact actuator in its class making it a good choice for space-critical applications. Available in five models with forces from 20 to 5,800 lb-force and strokes from 4 to 40 inches, 3-phase or single-phase ac motors. Mini actuators with a rolled acme lead screw are predominantly dynamically self-locking. Options include feedback potentiometer, encoder and force-dependent shutoff.
ACTUATOR OFFERS HIGH SPEEDS, LOADS AND THRUST
With the trend in electric actuators toward higher speeds, loads and thrust, a new belt drive (B3W) from Tol-O-Matic extends the range of previous products. The B3W achieves speeds up to 200 inch/sec (5 m/sec) and load (Fz) ranges between 591 (2.6 kN) and 4,635 lbf (20.6 kN). Actuator thrust tops out at 325 lbf (1.4 kN) depending upon carrier options. Any stroke increments to 292 inches (7.4m) are made to order. The B3W is designed for high wear resistance, repeatable accuracy and high load capacities. Features such as a patented bearing system at drive and idle pulleys, stainless steel dust band and a polyurethane steel belt provide performance with consistent tracking throughout actuator life. Full access to idle pulley simplifies alignment adjustments and tensioning. The B3W is available in either a one-piece direct drive housing for optimal motor alignment and support, or a reduction drive option for reduced inertia and motor torque.
SRX-150 HEAVY-DUTY LINEAR ACTUATOR
The heavy-duty SRX-150 linear actuator from Bishop-Wisecarver is a high precision, compact aluminum profile linear actuator available in belt or ball screw driven versions. With a smaller footprint than similar units, the company says the new actuator provides up to double the roll moment capacity of screw driven products and nearly five times that of other belt driven actuators. SRX-150 can handle load up to 66 kN dynamic load rating and provide speeds up to 5 m/s. Features such as zero backlash, high speed and long stroke operation are targeted for applications including high load gantry systems, pick and place and heavy transfer equipment for industries such as automotive/transportation, industrial packaging, heavy machinery and glass handling. Standard features include NSK K1 lubrication Units for maintenance free operation, and end of travel high energy absorbing bumpers, which help to eliminate damage caused by accidental crashes, particularly during system setup.
ACTUATOR OFFERS HIGH SPEEDS, LOADS AND THRUST
Type VLA actuators from THK use fewer components and lower overall system costs by using a LM Guide for its base. Type SRS LM Guides use the company's patented Caged Technology to separate rolling elements with a synthetic resin cage that retains grease and reduces maintenance costs. To ensure optimal lubrication within the ball screw unit, the unit incorporates a QZ lubricator. The Type VLA actuator is designed as a replacement for pneumatic cylinders in many applications, since it electromechanical components offer improved energy efficiency, as well as cleaner and quieter operation. Contamination from lubricants, audible noise and damaging friction are reduced. The Type VLA is available in slide and cylinder types, and is compatible with most popular ac or dc servomotor controller packages. Rated speeds on the actuators range from 300 to 600 mm/s; ball screw leads are from 6 to 12 mm.
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