Making servo driven systems easier
Published: 10 July 2012 - Neil Mead
Machine builders strive constantly to improve their competitiveness. Servo driven systems are often a significant item in their build expenditure with high costs to purchase, install and commission. The Lenze 8400 TopLine drives are claimed to reduce costs through lower purchase prices, small size, leading to reduced panel costs, and high performance that increases productivity. Programming software is simple and free which all contributes towards to reduced workload for the designer and machine builder.
The Lenze 8400 TopLine is a servo drive for synchronous and asynchronous motors that sits at the top of the 8400 frequency inverter range. As such it is based on products in volume manufacture which leads to competitive pricing in the servo drive market. Latest technology gives middle to high-end servo performance with compact dimensions. Synchronous and asynchronous motors can be run open-loop or, for more precise control, with feedback from incremental or absolute encoders. On board is software for positioning, electrical gearbox and management of holding brakes. Safe Torque Off to Category 4, Performance Level e, is a further option whose low cost is normally justified by a reduction in external safety components.
With the flexibility to handle different types of motors and feedback, TopLine suits the majority of applications in the power range 0.55 to 45kW, 3.0 to 89A rated current. Three typical applications that illustrate its use are palletising, food portioning and paper winding machinery.
Palletising machines require smooth positioning with medium to high dynamics. The 8400 TopLine scores highly here with 200 per cent peak torque available for three seconds and smooth ‘S’ shaped ramps for acceleration and deceleration.
Stop-start applications such as food portioning and paper cutting run at high cyclic frequencies of operation. Where the requirement for precision is moderate, it may be possible to combine the 8400 TopLine with a standard IEC framed asynchronous motor, albeit with feedback. High precision will demand the extra expense of a synchronous servo motor and control from a higher level IPC. This in turn puts a demand on the bus communications between the drive and the controller. Here standard plug-in modules are available for the drive with either of the fast realtime buses EtherCAT or Profinet.
Paper winding machinery and other web-based applications for plastic and foil require smooth delivery of torque and medium to high accuracy on a speed setpoint. The 8400 TopLine has as standard an electrical gearbox function, also known as electrical shaft. A separate axis bus links drives specifically for this purpose and precise control of speed, angle or torque can be achieved between the master and slave drives.