By Thorsten Sienk, AMK
First unwind, then rewind – and print, laminate, and die cut in between. The UR Precision U unwinding system of Kocher+Beck is designed to feed web material to printing and converting machines nonstop from the role. The system is driven by centralized and decentralized servo technology from AMK. Because the drive technology is placed directly in the process, the size of the control cabinet is minimized – and more compact systems can be designed and more easily combined with printing and converting machines. This applies, in particular, to the matrix winder that rewinds the matrix after die cutting.
Nonstop Butt-Splicer of Kocher+Beck with unwinding unit (left) on rewinder.
Space is generally always tight in print production. In light of this fact, Kocher+Beck has now developed a matrix transfer rewinder for printed labels that is virtually free of control cabinets. The purpose of the unit is to perform nonstop rewinding of the self-adhesive matrix that is produced by the printing and die cutting of labels and is removed before the rewinding and subsequent delivery of products to the customer.
The fully automatic matrix transfer winder is placed between the unwinder and rewinder units during print production.
The matrix winder is usually placed directly on a printing machine between the unwinding and rewinding units, which are also driven by AMK servo technology. After the printing process, the matrix winder pulls off the sheet matrix from the web before this is rewound. Given the outlined use conditions, the machine is designed in such a way that it requires little space and can be combined with any printing machine. The design forms the basis for modularization of print production system components, made possible by decentralized drive technology from AMK in Kirchheim, Germany.
The AMKASYN servo inverters in the machine modules of Kocher+Beck perform precise adjustment of the web speed and tension and keep them within barely perceptible tolerances during winding. Increasingly thinner composite materials and sheets are being used that make handling more and more difficult. Against this backdrop, Kocher+Beck has pursued the clear goal from the start of the UR Precision series of controlling the web tension with high precision using the braking torque of the unwinder.
Sheets: Conversion is becoming more and more difficult due to increasingly thinner materials.
AMK has therefore designed an axis grouping for Kocher+Beck that features regenerative inverters and a shared DC link. The braking unwinder feeds its regenerative energy into this, which the rewinder, in turn, uses for drawing. Consequently, the drives of the transfer units "waste" only the energy difference resulting from process-related friction losses.
Turret in the unwinder and rewinder is driven with servo motors from the central control cabinet.
Regardless of whether centralized or decentralized servo inverters are used, they are supplied by a centralized power supply module directly via the DC link in the Kocher+Beck design. The interconnected operation of all axes is energy-efficient and also offers fewer components due to elimination of contactors and is designed for longer service life of all components in the control cabinet due to less heat development in the control cabinet. "Energy efficiency is becoming more and more important in our industry," said Karin Enderle, Division Manager for Winding Technology at Kocher+Beck, in particular with regard to the European printing machine business. Expectations are high and the use of modern servo technology with sophisticated motion control is also required.
AMK has integrated the software-based "Winding" motion control function as a technology function in its own AMKAMAC A5 controller with visualization. The combination of controller and touch monitor with glass display is integrated in the machine enclosure of the unwinders and rewinders in the direct vicinity of the process. Generally speaking, the preprogrammed motion control provides all important subfunctions for unwinding and rewinding – web tension determination with and without sensors, signal processing of pressure measuring boxes, pressure measuring computers and monitoring as well as the dancer position control with dancer monitoring.
From the networking perspective, the drive-related equipment with modern servo controllers can be integrated in the overall network via TCP/IP. In this way, the machine solutions of Kocher+Beck are positioned to process production and inspection data in real-time. Consistent communication from the drive level to the controller and even to the ERP or MES level is becoming more and more important in this context.
Customers also have greater flexibility to adapt their machines to new products, which ultimately makes their investment more future-proof. Because the extensive options for positioning that today's modern servo technology offers broadens the solution space, a machine can convert a large range of materials much more easily.
The matrix winder of Kocher+Beck demonstrates the performance of decentralized drive technology, especially when it comes to keeping machine modules as compact as possible. The overall solution also illustrates why there is a practical demand for combination solutions of centralized and decentralized servo axes in the form of customized equipment. With a view to Industry 4.0, the device networking possibilities also establish the basis for consistent data and thus opportunities for continuous process optimizations.