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Promess, Inc. has introduced a new servo-based electro-mechanical actuator intended for applications requiring programmable rapid non-stop motion at frequencies not well suited for ballscrew-type presses.  The Bolt Actuator achieves this new level of performance through Promess’ Dual-Eccentric Servo technology.  This new innovation employs an eccentric shaft mounted inside an eccentric sleeve, both of which are independently servo controlled, to provide dynamic stroke-length and/or force/distance profile adjustment in real-time.

The Bolt Actuator has an integral force sensor that measures reactive load in real-time.  Bolt is married with the Promess UltraPRO control system to form a complete package to handle applications such as fatique testing, long-term characterization of mechanical parts, high-speed assembly, metal forming, die compaction of powdered metals, and materials packaging.

Promess will initially offer the BOLT in two configurations, each having a variable stroke length of 0 to 26 mm:  a 4kN model that operates from 0 to 8 Hz and a 1 kN model that extends to 30 Hz.  Future designs will easily scale up to more than 60 kN at motion frequencies up to 75 Hz.

The Bolt Actuator is capable of 0.0005 mm resolution, 0.039 mm position accuracy and 0.005 mm repeatability. The Promess UltraPRO controller used in the Bolt system also can accept and integrate input from a broad range of external sensors including position transducers and load cells.

 “The Bolt fills a niche for a programmable servo press that can operate at relatively high frequencies while allowing the stroke to be dynamically adjusted for length, force, speed or any combination of the them,” explained Glenn Nausley, President. “It’s an ideal solution for applications like fatigue testing as well as assembly operations including pin insertion, stamping, capping, staking or plugging.

“A ballscrew driven linear servo press requires the motor to stop and reverse direction at the beginning and end of every stroke; the time required to do that plus the associated accel/decel time limits the practical frequency it can achieve. Repetitive motion over a small range also concentrates wear to that portion of the ballscrew. The Bolt eliminates both of those issues.”

The BOLT Actuator can adjust any combination of speed, force and distance “on the fly” within a single stroke based either on a pre-programmed profile or sensor feedback.  The software package included with the initial Bolt offering produces pure sinusoidal motion. Future versions will allow for a wider range of profiles, for example, rapid approach/slow press/rapid retract which can be useful in certain assembly operations.

“The UltraPRO is easily integrated into existing data storage and analysis systems,” Glenn Nausley added. “That makes it simple to document test and/or assembly operations to provide traceability for individual products which is extremely important in applications like medical device manufacture.”