OPTIMISED SOLUTIONS FOR REGISTERED EMBOSSING

Dieffenbacher­ Zaisenhausen now offers the coating industry even greater scope for design in the form of newly developed systems which deliver an extremely high level of positioning accuracy, thus ensuring that the finished products are more vivid and natural in appearance.

Suppliers of laminate flooring have succeeded in boosting the appeal of their products and increasing their market shares by continually developing attractive patterns and surface finishes, giving consumers exactly what they want, namely high-quality products with a realistic look and feel. The design of the surface structure is decisive. It is now possible to produce a three-dimensional appearance and, therefore, create the natural and authentic-looking products that the market demands. On a technical level, manufacturers face the stiff challenge of matching the decorative pattern to the surface structure as precisely as possible. If there is a slight discrepancy, the customer's illusion of authenticity is shattered and the value of the product is diminished considerably. One example of this would be a tile pattern with non-­matching grout lines.

In series production, modern, high-quality coating plants of conventional design allow near- perfect congruence in pattern and structure, within certain tolerances. However, for many products, the requirements are far more stringent than even this.  The Dieffenbacher­ Zaisenhausen plant concept is designed for those stages of the production process, which are decisive with respect to the quality and the accuracy of the embossing on the finished product. In the loading area, for example, the specially developed positioning belt has an optical detection system for determining the exact position of the decorative film, with a resolution of upto O.O3mm. Motor-driven correcting elements enable any deviations from the desired position, lengthways or crossways, to be put right immediately.

One of the main features to be modified was the motion sequence in the loading and pressing area, which is critical with regard to positioning accuracy in conventional plants. Here all the guides and bearings were designed using highly precise, state-of-the-art components. Positioning in the limit positions is highly accurate. All of the drives are asynchronous servomotors with low-backlash gears and frequency converters. When it came to developing a system for depositing the press material in the press, the main aim was to find an innovative ant viable solution to maintain the high degree of positioning accuracy already achieved up to this point in the production process. To this end, the entire loading and depositing system had to be re-designed and re-engineered. The kinematics of the depositing process was modified to incorporate an additional loading tray tilting function in conjunction with extremely precise control and position strategies.

Even the short-cycle press itself underwent major changes. Firstly it was equipped with a precision guide for the stroke movement. Furthermore, the guide is hydraulically preloaded, thus ensuring an extremely low degree of play. In extreme situations, it yields hydraulically and thus allows the press ram to re-align itself automatically. The caul plate holders were designed to allow extremely precise locating of the caul plates on the one hand and safe, simple caul plate changes (semi-automatic caul plate changes) on the other hand, all in keeping with Dieffenbacher's high quality standards. Dieffenbacher opted to use the tried-and-trusted SIEMENS S 7 system for the control duties. For the program developers, an effective plant concept needs an easy-to-understand and user-friendly visualization system. Great importance was also attached to keeping the system open for corrections from outside so that it is always possible to influence the process and its individual parameters.