Perfect Colour Distribution

09.03.2015 11:03:00

Automated painting of ROSTA AG rubber spring systems using Cognex vision systems and the robotics expertise of Robotec Solutions AG

Spring parts protect equipment from wear. High-quality varnishes protect spring parts from corrosion. In order to keep the rubber spring systems of ROSTA AG perfectly painted in large quantities, Robotec Solutions AG has automated its previously partly manually operated inventory system. Cognex vision systems detect hanging carriers equipped with 2D codes, enabling fully automatic program control of painting robots.

Springs allow repetition of alternating movements without overloading machinery, plants, and moving vehicle parts. The rubber spring parts of Swiss ROSTA AG, already patented in 1942, provide equally elegant and simple, low-wear damping. The ROSTA part is a crafted spring with four preloaded special rubber bodies between the outer casing, and a 45 degree offset inner square profile. These innovative rubber spring systems for the machine and automotive industries are able to include several components such as a torsion spring, pivot bearing and shock absorber due to quite compactly built elastic pivot bearings. They operate silently and maintenance-free. The 40 g to 80 kg rubber spring systems are protected from corrosion by a high-quality Aqualack. In the beginning of 2014, the company modernized its paint shop, converting to fully automatic operation of painting robots. This modernization was carried out by Swiss specialist for robot-based automation from Robotec Solutions AG. Introduction of a vision system from Cognex was a landmark in the truest sense of innovation. Equipped with a DataMan 8100 wireless hand-held reader and two DataMan 50S stationary code readers, the paint shop automatically assigns spring parts travelling on an overhead track to a product-specific painting program.

Powered paint spraying
Up to the end of 2013, rubber spring parts were primed by means of linear portal robots and finish painted by hand, but the new system enables fully automatic painting today. For this purpose, two 6-axis, articulated-arm painting robots, programmed and installed by the experts from Robotec Solutions AG are in operation in the paint booth. The painting itself is performed using electrostatically charged Aqualack. When 100 kilovolt-ionized paint impinges on spring parts grounded via the hanger, it adapts completely to their surfaces, forming a hermetically sealed protective layer.
In order for the robot control to know exactly what product type is located in front of the flat spray paint nozzle, both the carriers travelling on the overhead track and the products must be made identifiable and traceable during the entire painting process. This was achieved by encoding the hanging carriers with robust, hard-wearing 2D codes, and the rubber spring parts with 1D codes from the relevant product data sheets.
The first step in the code reading chain is to match products attached to the hanging carriers using the DataMan 8100 of Cognex. The combination of product and hanging carrier codes provides unique information to the system control as to which product is at what point in the process chain. A short "shot" from a hand-held Cognex on a product data sheet 1D code is sufficient to subsequently read several 2D codes from hanging carriers.

Distance reading
Due to its long range, the DataMan 8100 Wireless provides a great advantage as it enables employees to scan 2D codes by hand along the entire 20 m carrier path. They thus have a time buffer during the passage of a hanger scanned at the plant entrance, and are able to hook up new product carriers. Another benefit of the DataMan 8100 is its capacity to easily read the approx. 2 x 2 cm adhesive labels with the printed 2D codes on the hanging carrier from a distance of just over one metre. Integrated decoding algorithms allow rapid decoding of 2D codes. The large reading distance is made possible due to the special LiquidLens optics. The integrated radio module and intelligent base station of the DataMan 8100 were designed specifically for wireless code reading applications over longer distances.

The correct program
When assignment of hangers and products is complete, two stationary DataMan 50S code readers become active at a distance of about 1.5 m shortly before entry into the paint booth. By reading the 2D code, the first DataMan 50S checks whether a hanger has been assigned a product. It triggers opening and closing of track points that initiate and halt further transport into the paint booth. The second DataMan 50S re-reads the 2D code and returns the product-specific program information to the robot control or paint shop control. With its small size of only 23.5 mm x 43.5 mm x 27 mm, the DataMan code reader in the 50 series can be easily integrated in the tightest fitting locations, which played an important role regarding installation in the existing system of ROSTA AG. During the next pass through the spray booth, hanger 2D codes are protected by a cover against contamination from the paint spray. Depending on part size, 20,000 to 30,000 parts per week pass through this modernized plant.

Performance is the decisive factor
The large reading distance of the DataMan 8100 wireless code reader was decisive as regards contracting the project order in favour of Robotec Solutions AG. Moreover, decades of experience and its high level of expertise in implementing customized applications played a crucial role. The powerful team of robotics specialist were also able to easily manage modernizing the plant during just three weeks of commissioning at the turn of the year 2013/2014. Last but not least, thanks to the equally innovative, powerful and robust vision system of Cognex, the plant has been running smoothly ever since.

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DataMan 8100 reads the 2D codes of the hanging carrier rapidly and reliably even at a distance of about 1 m.

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Both painting robots of Robotec Solutions AG in action.

About Cognex
Cognex Corporation designs, develops, manufactures and markets machine vision and industrial ID systems, or devices that can "see." Cognex is the world's leader in the machine vision and industrial ID industries; its vision and ID systems are used around the world for a wide range of inspection, identification and guidance applications throughout the manufacturing and distribution process. Key markets are the Automotive, Food & Beverage, Pharma and Logistics industries, as well as OEMs. Headquartered in Massachusetts, USA, Cognex has regional offices and distributors located throughout North America, Europe, Asia and Latin America. Also in Eastern Europe, Cognex is constantly expanding its local presence, offering now technical support and classroom trainings in its offices in Wroclaw, Poland, and Budapest, Hungary. For details, visit Cognex on-line at www.cognex.com.

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