Safe and sound: New drive and safety controls in Shepparton
Published: March 6, 2009A substantial drive and safety control upgrade has accompanied the five-year evolution of Shepparton Newspapers’ Goss Community to a six-tower, predominantly full-colour press.
A second stage has seen increased clutching flexibility and safety control added at the central Victorian site, which prints the ‘Shepparton News’ and a range of group and commercial publications ranging from 800 to 70,000 copies, and four to 120-pages.
Printing division general manager Paul Kelly says ongoing maintenance issues, coupled with escalating demand for full-colour offset printing, ultimately catalysed the upgrade which began in in 2003. Three four-high towers and a larger folder were added to the existing two four-high and several two-high units.
A mechanical clutch to allow the upgraded line to operate as a whole or as two presses, prompted the drive upgrade – an opportunity to address reliability issues with the DC on the older part of the press – for which Rockwell Automation was the contractor.
“We’d been having all sorts of problems with the existing press – breakdowns once or twice a month that would take two or three hours to fix,” says Kelly. “These would often lead to production penalties.”
Apart from the problem of finding technical support for the motors and drives to get the press back online quickly, sometimes at 3 am, a holistic view was needed production flexibility, safety requirements and future needs.
The existing DC drive was replaced with a new AC system with five Reliance AC motors each with 93kW Allen-Bradley drives – two pairs for the new section and three for the old. These are interfaced to two controllers, which provide intelligent drive and logic control, with peer-to-peer communications. The configuration allows the two press sections to function independently when the lineshaft clutch is open, and as one – with one drive assigned as ‘master’ – if it is not.
Local system integrator Terry Johnstone was brought in to assist with installation and commissioning, helping to address the issue of ongoing technical support, and a spare parts programme established.
Kelly says the diagnostics ability and local support has made a huge difference: “We hardly ever get unplanned shuts anymore, but when we do, they only last around half an hour.”
An interface identifies where problems are occurring, so Johnstone can be advised in advance of a visit.
A second project followed with the need in 2006 to split the press further via three additional clutch points, so that one press can incorporate three, four, five or six four-high units, with the balance as a second press.
The key challenge, says Kelly, was ensuring that operation of the press remained safe. “It was easy for me to say exactly what I wanted, but we had to make sure it fitted within the safety constraints,” he says.
A risk assessment followed, reinforcing and clarifying safety issues, and delivering a manageable project with specific goals. The main safety issues related to the numerous combinations of clutch configurations, which were manually set and then entered into the control and drive system.
The system keeps track of which printing units are clutched together, and must control how the units behave during plating up, with each unit’s movement limited to a locally-controlled inching function.
The resulting safety control system has been founded on an Allen-Bradley safety controller, integrated with one of the controllers from the 2003 upgrade. This monitors the inputs from a series of paired proximity switches fitted to each of the four clutch points.
The safety audit also revealed several additional areas where safety could be improved, leading to the installation of improved mechanical guarding on the units and ‘safe stop’ buttons on each unit.
The safety controller not only responds to any of four ‘emergency stops’ (shutting down the entire press) but will shut down a section if a ‘safe stop’ button on a print unit is pressed or a roller guard opened. It also initiates a controlled shut if a web breaks, with the web first diverted from the back of the folder to avoid a jam.
Kelly says the journey of the past five years has been “well and truly” worth the effort: “With all the upgrade work carefully managed to be carried out during scheduled downtime and maintenance periods, the plant never missed a day’s production.”
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