Couplings provide dampener for inserters

Edited by the Engineeringtalk editorial team Jan 31, 2006

CD couplings damp out shock and vibration from partition inserters' vertical reciprocating and intermittent motion and maintain insertion accuracy cycle after cycle.

The SF-400 partition inserters from Wayne Automation cycle once every second and travel 96.5cm vertically.

Every up-down cycle accurately inserts solid fibre or corrugated partitions into cartons that hold bottles and plastic containers ready for shipment.

To maintain repeatable accuracy round the clock at these high speeds, they use servomotors connected to backlash-free Zero-Max CD couplings.

These couplings damp out shock and vibration from the inserters' vertical reciprocating and intermittent motion and maintain insertion accuracy cycle after cycle.

"To operate without problems, conventional vertical inserters require near perfect fibre or corrugated partitions," said Jay Bachman, VP of Engineering for Wayne.

"In contrast, the SF-400 inserters have designed-in features, including servo drive systems, that help deal with less than perfect materials".

"Unlike conventional systems which rely on gravity during the insertion process, the SF-400 maintains complete insertion control from the time the partition is picked off the magazine until is fully inserted into the case".

"This ensures correct partition placement into the case every cycle".

The drive system for the vertical inserter mechanism is powered by an Allen Bradley servomotor connected to a planetary reduction gearbox.

The motor transmits torque to the inserter via a floating shaft Zero-Max CD coupling configuration connected at both ends to two gearboxes.

These gearboxes are connected to two timing belt drive pulley gearboxes.

The combination of both intermittent and reciprocating motions at 1000rev/min (96.5cm one-way travel for every one second cycle) is demanding on the system's drive train.

Torque loads are a big factor in this setup with cyclical peak torques approaching 60% of the motor torque with vertical load lift up to 90kg.

A coupling design was needed that would handle these forces and one that could be positioned at both ends of the two gearboxes to equalise tension on both timing belts.

The firm chose the Zero-Max CD 6F30-AC floating shaft coupling.

The SF-400 coupling application is unique because of the 71cm span from one coupling's outer connecting hub to the second coupling's outer hub.

Also, this setup is a test of each coupling's composite disc design integrity that has a rated torque of 90Nm.

While the CD coupling disc pack transmits torque similar to any conventional coupling, it does a better job of dampening backlash and shock without coupling fatigue, which can occur in a fast-moving, high torque system such as the SF-400.

The disc pack at each shaft end resists fatigue through its open arm disc design.

Made of highly durable composite material, the disc pack absorbs any shock from the servomotor's intermittent motion while maintaining a zero backlash condition.

Also, the coupling's disc design and hub configuration provide support for the floating shaft component without imposing excessive radial loads on the connected equipment and bearings.

Precision machining of the coupling components also gives the connection dynamic balance for smooth, quiet operation.