Steel, shipped from the customer, processed and returned to the customer
For one of its steel suppliers Rösler built a fully automatic, linked 2-in-1 preservation line for plates and profiles. The high manufacturing depth of Rösler with its own steel cutting, bending and welding departments was key to meet the quality demands of the customer.
Klöckner & Co. Germany GmbH, a leading steel supplier, expects top quality for the various steel components, which must frequently be blast cleaned and coated with a protective primer. To date, at its Bremen location, which supplies predominantly shipyards, the company had these services done by external job shops. To fulfill customer requirements faster and more flexible, it was decided to bring the blast cleaning and painting operations in-house by investing in a preservation line. Rösler was awarded this important project, because similar installations are successfully running at other Klöckner customers. Moreover, the company was impressed by the excellent handling of the pre-project phase by Rösler’s sales team and, last-but-not-least, by the high manufacturing depth at Rösler considered to be a significant factor for first class quality.
Engineering and steel processing (cutting, welding, etc.) work hand-in-hand
It begins with the engineering phase, during which suggestions and ideas from various manufacturing stages are picked up and utilized, frequently resulting in significant design improvements. Once the design is completed the various equipment components are laser cut and bent. The subsequent blast cleaning stage facilitates not only the work of the welding crew but also ensures the best possible quality of the welding seams. The welding department has seven small and five large welding stations. The latter can be combined into one station that allows producing assemblies up to 36 m long in one single piece with minimal tolerances. Each assembly is checked for the proper size of the welding seams, overall dimensional integrity and optical appearance, before it is released for the next manufacturing steps consisting of an additional shot blast process and painting.
Efficient, fully automatic blast cleaning of plates and profiles
The preservation line, designed as a 2-in-1 system, consists of a profile and a main/plate line with separate loading stations, one painting booth with drier, a thermal after burning system and three unload stations. With this configuration Klöckner can handle components up to 3,200 mm wide, 16,000 mm long and 100 mm thick. All line units are linked with each other and connected to the company’s higher-level production control system. During the loading phase the operator enters information regarding the shot blasting parameters, the paint color and at which stocking location the material has to be deposited after being processed.
The profiles come in bundles to the preservation line where they are placed on a cross-conveyor to be separated into single pieces. The equipment design already foresees a leveling station to be retrofitted at a later date, if the customer decides that such a unit is needed. In the next step the profiles are combined into batches of 3,200 mm width and fed into the plate line at a high priority. During this preparation phase steel plates can be processed continuously allowing full use of the system capacity. In the master line the plates and profiles pass through a blow-off station to remove water and loose contaminants and, subsequently, through a pre-heater. From there they are transferred to a roller conveyor shot blast machine RRB 34/6-HD. Eight Gamma 400 G turbines with 22 kW drive power each, placed on the roof and bottom of the blast chamber, ensure that the specified blast cleaning results of SA 2,5 are safely and consistently achieved. The blast chamber, made from manganese steel is equipped with easily exchangeable manganese steel plates for additional wear protection. Carried out blast media and dust are removed in the blow-off/brush-off station located behind the blast chamber.
Highly flexible painting system
Painting of the plates and profiles is typically done with solvent-based 2-component paint in two colors, which are automatically mixed as required. To quickly fulfill special color requests by customers the paint system is also equipped with a third, manual mixing station for solvent-based and water-based paints. The paint is applied from above and below with eight paint guns. Each individual paint gun is controlled by a work piece recognition system and a control device that monitors the work piece length. This keeps overspray at an absolute minimum. After passing through the drier the plates and profiles are transported to their pre-determined unload station from where they can immediately be loaded onto waiting trucks.