Control & Automation

New ServoBelt precision rotary stages provide competitive belt driven alternative to direct drive and worm-wheel variants

Phil Black - PII Editor 03/12/2009

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Motorised belt-driven rotary stages

• Pre-tensioned belt driven rotary stage provides low cost solution for high precision angular positioning
• Flexible options include wide choice of encoder feedback and motor mount configuration

A new range has been launched of motorised belt-driven rotary stages from USA servo-mechanics innovator Bell-Everman that combine high precision positioning with excellent dynamic capability in a competitively priced package.

The ServoBelt Precision Rotary Stage uses a novel pre-tensioned belt drive mechanism for high stiffness and maximum positioning repeatability. Offering a practical and lower cost alternative to direct-drive rotary tables, and with improved dynamic performance over tradition worm-wheel stages, the 5:1 belt reduction ratio provides an advantageous motor-to-load inertia match whilst allowing high speeds and rapid accelerations.

The compact design includes a 165 mm diameter tabletop with a large 100 mm aperture to allow for cabling and services feed-through. The stage features pre-lubricated, long-life duplex type angular contact bearings for smooth motion, practical load capacity and maximum stage rigidity, with a NEMA 23 sized servo motor providing up to 6.6 Nm continuous torque at speeds to 1200 rpm. At just 61 mm high, the low profile stage is easily integrated into applications with user configurable above- or below-stage motor mounting options for complete installation flexibility. Side motor mount options are also available.

A wide choice of position feedback options include rear motor mounted optical encoders or direct table mounted ring encoders which can provide a positioning resolution from 14 arc-sec to 0.4 arc-sec – even for such a high resolution, the motor speed can be over 80 rpm. Bi-directional repeatability through these options is from 160 arc-sec down to just 0.9 arc-sec. Overall geometric accuracy is stated at 2.5 microns TIR (or better) at any point on the stage.

The ServoBelt Rotary range is aimed at high precision angular positioning in production and test systems applications for medium-heavy mechanical processes and metrology. The durable anodised aluminium housing is finished with stainless steel hardware and the tabletop can be machined to suit customer interfacing.

The Servobelt is available for use with third party NEMA 23 frame servo or stepper motors and they provide a complete design and commissioning service for customised mechatronics systems that can combine linear and rotary positioning components, motor drives and motion controls.