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Freeglass Produces Plastic Panorama Roof for Mercedes GL


The third dimension for more view

An open view to the sky gives a positive feeling to many motorists when driving. Provided with daylight, the ambiance in the car is more pleasant and less narrowed. This conception results in panorama roofs being more and more popular. Freeglass (Schwaikheim, Germany) is one of the leading suppliers for components shaped in 3-D, similar to glass. Using injection molded parts from polycarbonate allow shapes that are not possible in glass. If the passengers of a Mercedes GL desire shade, a robot from Reis Robotics fixes a roller blind to the sun roof module - using a state-of-the-art gluing technique.

Freeglass is a subsidiary of the global group Saint-Gobain Sekurit and developed from a joint venture. Beginning in 1998, the first plastic screens were produced in Schwaikheim. With car window screen modules, roof systems, and integrated sheathings from plastics, Freeglass opens new perspectives for the automotive design. Plastic elements can be shaped in three dimensions, they are easy to produce, and at the same time, they fulfill all glass standards.

Freeglass laid the cornerstone for their success with the development of a fixed plastic window from polycarbonate with scratch-proof coating for the Smart ForTwo. A comparable but more tinted material is used for the panorama roof of the luxury-SUV Mercedes GL. In one of the biggest injection molding machines of Europe with swivel-platen technology, Freeglass produces the fixed, one-piece panoramic roof from transparent and nontransparent elements in one operation. A two-part technique allows the production of an injection molded part in a two-stage process (transparent and nontransparent). Thus, a second section of the injection-molded part can be produced that, together with the first section, results in a part that is considerably lighter than similar glass elements. Furthermore, this solution is suitable to integrate an invisible antenna in the module, the receiving characteristics of which are not shadowed at all by metals or metalized screens.

Sun: in or out?

The friendly atmosphere of sunlight in vehicles is not as desirable when it is very hot outside. For this reason, the wish arose for a shadowing option in the panoramic roof. Accordingly, a roller blind was provided. The fixing of the frame for the roller blind to the roof module was a challenge for the developers at Freeglass.

"Already the planned piece number rendered a manual fixation of the frame impossible," Jens Kirchhoff explains, strategic purchasing department Freeglass. "Looking for an automated gluing system, we hit upon Reis Robotics very fast, because they have been competent for years in the fields of plastic processing and gluing technique. Now it was a matter of developing a process able to cope with the special requirements because in addition to glue application, exact positioning, and a holding time with mold constraint had to be considered in order to ensure that the parts were connected firmly enough for further handling."

In close cooperation between the senior developer from Freeglass, Walter Stopp, and the team from Reis Robotics, the gluing system was originated in 2005. As a compact cell, it integrates optimally with the preceding and succeeding processing steps.

Sequence in the system

The frame for the roller blind is prepared automatically for the gluing procedure. This includes cleaning with a special cleaner and application of an adhesion enhancing primer. At this point, the 6-axis Reis robot type RV130, using a special fixture, picks up the frame at the hand-over point exactly centered from the side turned away from the glue. For this purpose, the robot docks to the fixture device.

Next, the frame is turned with the side to be glued pointing upward, because the glue dispensing head from Reis Robotics is installed above the robot. This dispensing head can be lowered for ease of maintenance. Before each new gluing operation, a special mechanism ensures that glue remnants are stripped off from the nozzle.

In the next step, the robot guides the frame module beneath the dosing nozzle, which forms a triangular bead as the frame is moved underneath. In a very homogeneous movement, the robot moves the component with its three-dimensional contours beneath a static nozzle. Controlled as the seventh axis and absolutely synchronous to the robot movement, the orientation of the turning nozzle is adjusted at the four corners in order to align the glue bead shape always parallel to the frame and to apply it to all places in equally thick dimensions. In this system configuration, the robot control serves as central control for both systems.

When the glue application is finished, the robot moves the frame part to a parallel paternoster line. Here, the panoramic roof modules are precisely fixed on goods carriers. For maximum positioning accuracy, the robot docks to the goods carrier during joining.

Tighteners at the goods carrier press the frame to the final gap dimension and continue fixing the frame to the roof module. The robot loosens its connection and moves back for the next part. In a paternoster conveyor system, the goods carriers are conveyed for another six minutes together with the clamping in order to give the glue the required drying time for later handling; finally, the glued roof modules are removed and fed to further processing steps.

Result

"Reis Robotics became a preferred partner for gluing technique automation solutions," says Ulrich Riegler, head of project management at Freeglass, "because the experts understood and implemented our requirements very quickly. Cooperation with 2KM, the supplier of the gluing system, also went smoothly. The gluing cell installed in our works after a project phase of only four months meets our requirements and the high requirements of the automotive industry. During the introduction, the controls of the gluing system and robot were synchronized to each other in an optimum manner so that the result is of first-class quality."

Freeglass sees many challenges approaching the innovative and flexibly configurable products; therefore, the described gluing cell surely is only the beginning in a new, sunny automotive future!

Freeglass

Freeglass GmbH & Co. KG is world market leader on the field "plastic glazing." In Schwaikheim near Stuttgart, three-dimensional modules are developed and produced with state-of-the-art technologies and delivered to automotive manufacturers worldwide. Freeglass was founded in 2001 as joint venture of the former Schefenacker AG and Saint-Gobain Sekurit after the first plastic screens had been developed and produced together since 1998. Since the end of 2007, Freeglass has been a 100% subsidiary of Saint-Gobain-Sekurit.

Product range:

- Fixed door windows

- Transparent roof systems

- Rear windows/rear modules

Reis GmbH & Co. KG Maschinenfabrik Reis Robotics USA, Inc. www.reisrobotics.com www.reisroboticsusa.com Walter-Reis-Str.1 1320 Holmes Road 63785 Obernburg Elgin, IL 60123 Germany 847-741-9500

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