Ball screw actuators can't normally support side loads without the addition of a bulky auxiliary guide and support system. Strongarm™, a compact side-load-capable ball screw linear actuator, supports bending moments and side loads with a counterbalance mechanism that isolates such forces using internal, adjustable, preloaded cams.
In the actuator, the counterbalance contains a patent-pending cam mechanism that conveys compensating forces to a drive-nut adapter at the rear of the piston. Six adjustable eccentrics deflect four cam beams proportional to the actual payload and extension, with minimal preload on the cam beams as the piston retracts.
During extension, as the moment arm increases, cam rollers travel along to proportionally preload the cam beams. As a result, the rollers move into a counterbalance position in the drive-nut adapter. The piston, continually seated in a journal bearing at the front of the actuator, offsets bending moments at any given position handling axial tension and compression loads while resisting bending.
| An internal counterbalance mechanism counteracts sideloads, and keeps the actuator design compact.
James Haury, E-Drive Design, 124 Hebron Ave., Glastonbury, CT 06033; Tel: (800) 878-1157; Fax: (860) 659-2185; E-mail: email@example.com.
With some spring-latch assemblies it's hard to tell whether fastener separation is complete. Especially if the female and male portions aren't ejected away from each other with force upon release, and if the force to eject the latch is applied in the same direction as the force to secure it. By applying a triggering force in the same direction as the ejection force, a new bistable member for ejecting snap-fastener and spring-latch assemblies (Patent 5,870,806) avoids such problems, and integrates both the latching mechanism and ejecting mechanism in a single molded structure.
A continuously curved dome-shaped base portion inverts between convex and concave forms. An engaging protrusion forms a ring around the central apex of the bistable member that is wide enough to receive the head of the male portion. During inversion, the engaging protrusion moves toward the central apex to wrap around and engage the head of the male member. Upon release, recovered potential energy ejects the male, notifying the operator that separation from the bistable member is completed.
| When pressed by the male member, the bistable member stores potential energy. In response to a slight triggering force in the opposite direction, potential energy is released ejecting the male member away from the bistable member.
Robert P. Black Jr., 18532 Paseo Pueblo, Saratoga, CA 95070; Tel: (408) 374-7059; Fax: (408) 374-3005; E-mail: firstname.lastname@example.org
To create motion within a vacuum chamber, typical rotary feedthrough devices use a ferrofluid or O-rings to seal the shaft, or a magnetic feedthrough device. But ferrofluids are expensive and complicated, O-rings wear out, and magnetic couplings don't provide the positive connection required.
Instead, ChamberLink™ seamlessly integrates the harmonic drive with the chamber wall, keeping the motor and input elements on the chamber's ambient side and the geared output shaft on the vacuum side.
ChamberLink reduces particle count, downtime, and maintenance costs because there are no seals to wear out and fail. Moreover, vacuum is not compromised even if the motor is removed.
| ChamberLink combines an airtight rotary feedthrough device with a harmonic drive servo actuator.
Mark Gould, Harmonic Drive Technologies, 247 Lynnfield St., Peabody, MA 01960-4905; Tel: (800) 921-3332; E-mail: email@example.com.