Edited by: Leslie Langnau, Managing Editor
An economic multi-axis motion controller and software is helping Rollem – a leading specialist print machinery manufacturer rapidly evolve its modular finishing system. The motion architecture made it easy to add another peripheral to the company’s print finishing equipment range, a stacking unit that collects and groups products such as business cards into finished quantities ready for shipping.
Rollem specializes in accurate cutting/perforating/scoring machines, with a focus on extreme accuracy enabling users to squeeze extra units out of production processes or standard paper sizes with the company’s finishing equipment.
At the heart of the current machinery range is a compact ABB controller called NextMove-ESB2. This compact unit controls up to eight servo and step motor axes, and includes onboard analog and digital I/O for general machine control, plus interfaces including a CANopen port for controlling distributed motion and I/O resources. Depending on the particular finishing line configuration and number of motion axes, one or more of these controllers is installed in the distributed control system. This architecture gives the company granular control that scales economically. The controller’s combination of motion and machine control functions also enhances versatility to meet the needs of new stations in the equipment family.
The newly designed Descending Card Stacker is typically installed as a third station on a print finishing line, following slitting and collating stations. This peripheral has a single axis of movement using a step motor, which dynamically varies the height of a stacking tray synchronized to a laser sensor detecting the position and height of printed items. In the case of playing card printing, the system can group multiple packs to create a ready-to-use Blackjack deck. In the business card world, the system will group specific printed quantities such as 250 or 500 into a stack for final shipping.
The step motor axis and its drive connect to the main controller and HMI through the print finishing line’s CANopen network. The MINT motion software language made it easy for developers to create code, as it uses clear English-like commands and has hundreds of keywords that provide single-command instructions for motion tasks.
In the case of the new stacker, Rollem’s main software developer Stuart Murphy wrote the control code and the additional code required for the machine’s HMI in under half a day, before testing it on the prototype electromechanical hardware.
Rollem is now installing the second generation of the multi-axis NextMove controller. A key selling point for Rollem was the MINT software development environment, with its rich library of ready-to-use motion control functions. MINT’s high-level commands are similar to the BASIC and PASCAL style programming languages that Murphy learned at college.
A production unit of the new stacker was installed on a Rollem line at an advanced print-ecommerce or ‘web2print’ company producing business cards. The complete print finishing line is known as Rollem Revolution, which handles sheet sizes up to 1020 x 720 mm.
A Revolution line consists of several stations. At the start of the process is a feeder with a vertical axis for raising a stack of sheets, driven by a 3-phase motor/inverter combination, which is controlled through the ABB NextMove’s onboard D/A converter.
A second servomotor axis drives the feed roller. A conveyor – driven by another motor/inverter combination – then moves the sheets onto registration and slitting. An optical sensor detects the registration mark and adjusts a guide rail.
The cutting system detects the leading edge of the paper and accelerates the blades to the conveyor speed before performing a single-direction ‘interrupt slit’ – which creates strips but leaves the outside edge connected. This border keeps the strips in place while the paper turns through 90-degrees for a second registration and slitting stage to separate the individual print items.
Rollem’s cutting system is rigid, allowing accurate cutting suitable (for security items), at speeds up to 4000 sheets/hour. Each cutting module uses two servomotors, one to control the acceleration and return of the cutting head, and one for vertical positioning of the rotary blades. The next stage is collation. If the end product is business cards for example, separated cards are collated into a stack by three servomotor motion axes, which move the cards at an angle across the process area into a ‘gutter’ output channel.