Overhead Conveyors Benefit from Motor Drives

Overhead conveying systems, such as this one, often require complex drive systems that work best if managed by motor-drive units.

Multiple drive units, needed to handle the inclines, declines, and turns of overhead systems, require motor drives for reliable operation. 

As companies change to adapt to industry demands and needs, flexible systems are becoming more important than ever. Many companies are subject to producing more product with the same workforce and floor space. This often requires different plant layouts and creative floor-space management to optimize efficiency. In cases where additional production lines are being added to existing facilities, overhead conveyor systems are a flexible option to move product without impeding existing production. An added advantage is that floor-level production lines may not have to be moved or shut down to accommodate expansion that uses overhead conveying systems. This was the case with a recent expansion at a major tire producer that needed additional production to accommodate the increased demand for large truck tires.

Integration challenge

Integrating conveyor systems is not without challenges. A common issue when integrating such a system into existing infrastructure is that it often results in less than optimum routing where the shortest distance between points cannot be followed. Often, extra conveyor length is incurred when routing lines over and under pre-existing machinery and equipment. The extra conveyor length may require larger driving units such as motors and gearboxes.

In these cases, it’s common to add duplicate driving units to the system when a single unit would be too small or would subject the conveyor hardware to excessive stress. However, controlling multiple drive units adds some complexity. While a single control operating multiple drive motors might work, it may not be optimal because it may place stress on conveyor sections where inclines, declines, turns, and bends are encountered. Also, some motors may be overloaded by the greater load generated by conveyor contours. Controlling the multiple motors with multiple drives may be required.

A solution

The tire company recently installed a couple of new overhead conveyor lines to move product throughout their facility as part of a plant expansion. The length and layout of the overhead chain conveyor systems necessitated that there be multiple drive units located strategically throughout the span of the conveyor system to share the overall load and reduce stress on the chain and associated components.

The installation used Yaskawa America Inc., Waukegan, IL, (yaskawa.com), A1000 drives to control the 5- and 10-hp motors that were gearbox coupled into the overhead chain systems. The control integrator used standard Yaskawa drives with a self-contained load-sharing configuration to ensure each motor performs its share of the work.

The drives were configured in a master-slave arrangement with the slave drives using PID to match the load being produced in the master. In this case, the load was split between both drives, with each drive/motor producing 50% of the overall load. However, the drives can be easily adjusted to shift the load ratio if required by the system.

The master drives receive their reference and start/stop commands through the plant network. The slave drives regulate their output frequency appropriately in response to the speed and load signals from the master. No encoders or PLC programming were required to perform the load sharing.

The drives transfer the necessary signals through the drive’s standard terminal I/O. Had the drives been located a far distance from one another, the PLC could be used to transfer the data from master to slave through the network. Slave-drive response is set up using the PID gains, integral settings, and limits.

The startup was performed over a holiday weekend with assistance from Yaskawa. Both systems were commissioned the same morning using application note AN.AFD.39 as a base point and required almost no adjustment beyond the initial settings generated by Yaskawa’s application engineering team. The result was the much-needed increase in tire production. EP

For more information about motor drives for a variety of applications, visit yaskawa.com.

The Yaskawa U1000 Matrix motor drive offers an advanced design that provides direct AC-to-AC input to output power conversion and 98% efficiency. The drive is easy to install and set up. Learn more about the Yaskawa U1000 drive in a new podcast conversation with Christopher Jaszczolt, Product Manager, Matrix Drive, at Yaskawa America Inc., Waukegan, IL.