RETROFIT MECCANICI

Model R118: high-evolution electronic retrofit

Developed and installed in 2012

Model R118

The R118 is one of the oldest models to have undergone an electrical-part retrofitting. In this particular case, the press had been designed to print film, bare annealed aluminium up to 40 micron and paper up to 150 g/m2; max web width 1000 mm; printing cylinders repeat 400 ÷ 1000 mm; max printing speed 250 m/min.

Practicable on models:

On all R118, R128, R138, R148 models, but also on older models such as model 28R.

The case

The press was not equipped with a PLC, and all sequences were implemented via electromechanics (relays); motor-adjustment functions were achieved via analogical electronic components and dedicated equipment, including the drives, completely analogical as well and limited to controlled-diode bridges (SCR).

The press has been updated with new digital drives for DC motors and with the installation of a PLC, both for the management of the new drives and to create and improve the performance of the most important machine sequences (i.e., start-up, speed- and acceleration-slopes control, the automatic splice sequences on unwinder and rewinder, and so forth).

To this end several electric cabinets had to be replaced, notably the ones of the main drive, the unwinder and the rewinder. Cerutti’s choice has been the new Rockwell* automation platform with PowerFlexDC drives, ControlLogix PLC, I/O PLC series 1756 and 1734, which, by the way, are the current standard also for presses being manufactured today, when equipped with the Rockwell automation platform. Furthermore, a management system has been installed (the original press had none), thus obtaining a better management of the press, notably of the new functions, and the possibility of connecting the press to the “24/7 by Cerutti” remote-assistance service.

* The Rockwell automation platform is particularly suitable to this kind of retrofitting thanks to the availability of perfectly-integrated DC-motor drives, which Rockwell keeps on the market with important investments.

Schedule

4-weeks downtime plus one week of assistance during production. The press underwent a complete general test and inspection, as well as the main print tests with the relevant materials.

Target

The main goal of the retrofitting was to extend the plant’s technological life and to prevent long downtimes in the event of faults in components not available anymore on the market, notably in the electrical part.

The second goal was to optimize the press’ performance according to the ever-increasing variability in the materials to be printed.

Performance improvements

All of the most important sequences, also according to the several materials to be printed, have been improved and enriched. By installing the management system it has been possible to implement or improve several functions, such as the preset of operational units, tensions, positions of the compensating rollers, temperatures, acceleration slopes, taper on the rewinder according to the material, activation of a continuous (24/7/365) remote-assistance service.

Notes

On presses of this generation with a high-performance printing quality, this kind of retrofitting offers the best price / performance ratio, since it makes the press, even with its features of mechanical transmission with DC motors, perfectly aligned with the current state of the art in automation. These factors have a positive effect on the return on investment of such a retrofitting, taking into account also the further 10-15 years increase in the obsolescence term of the spare electronic components.