in Vol. 11 - September Issue - Year 2010
Automated roller conveyor shot blast machine produces excellent cleaning results for steel plates, beams and pipes. Double Is Better!
To be able to serve its customers with an expanded product range the steel trader Salzgitter Mannesmann Stahlhandel GmbH set up a new warehouse and steel processing plant in Zeithain in the state of Saxonia
The RRB 34/6-HD designed for parts of up to 3,400 mm (124") width and 600 mm (24") height is equipped with eight (8) EVO 38 high performance blast wheels. With a power of 37 kW and a blast media flow of 500 kg/min for each wheel, these newly designed twin disk blast wheels guarantee short processing times.
To simplify the material handling, the customer decided to load the steel components onto the roller conveyor from outside of the building. For this purpose the heavy duty roller conveyor with its rated load capacity of 3,000 kg/running meter was extended by 20 meters through the building wall. If no parts are being processed, the opening in the wall can be closed with an overhead door.
The RRB 16/5 was placed directly under the bridge cranes in the middle of the new building in Zeithain. This allows loading and blast cleaning of parts from both sides (inlet and outlet side) of the blast system. Two blow-off/brush-off stations located at each end of the blast chamber of the roller conveyor allow the complete removal of residual blast media, irrespective of the transport direction of the parts to be blasted.
Rösler RRB roller conveyor shot blast systems allow the quick and effective removal of rust, scale and other contaminations from the surface of steel plates, beams and pipes. For this purpose the Rösler engineers developed a modular equipment design which not only offers highly efficient blast cleaning solutions but can also be easily adapted to the most stringent customer requirements. Including the newly developed high performance twin disk EVO blast wheels, the many technical features in the RRB design convinced Salzgitter Mannesmann Stahlhandel GmbH to invest not only in one but two RRB systems at their facility in Zeithain.
The product range of the steel trading company Salzgitter Mannesmann Stahlhandel GmbH (SMSD) includes not only different kinds of steel plates, beams, pipes and pipe accessories but also various steel processing services. Within the Salzgitter group the SMSD GmbH, headquartered in Düsseldorf, is responsible for the group’s steel trading business in Austria, France, Germany and Switzerland. In line with the philosophy of maintaining a close physical proximity to its customers, the SMSD GmbH in Germany maintains warehouses and sales offices in all 15 federal states. In order to serve its customers with a wider range of products, the company recently opened a new facility in the town of Zeithain in the state of Saxonia. At this new facility SMSD not only stocks a full range of steel products, but it is now also able to offer various steel processing services. Among other steel processing systems the Zeithain facility includes two Rösler RRB roller conveyor shot blast machines. Says Manfred Stach, the manager responsible for warehousing and logistics: "We requested quotes from several shot blast equipment manufacturers. Key factors for our decision to go with Rösler were (1) the convincing technical concept and (2) the excellent quality of the Rösler equipment".
Heavy duty roller conveyor handles extra heavy loads
The larger of the two RRB systems, the RRB 34/6-HD, is mainly utilized for de-rusting and de-scaling of up to 3,400 mm (134") wide steel plates. But it can also be used for processing other steel components with a maximum height of 600 mm (24"). To simplify the material handling, the customer decided to load the steel components onto the roller conveyor from outside of the building. For this purpose the heavy duty roller conveyor with its rated load capacity of 3,000 kg/running meter was extended by 20 meters through the building wall. If no parts are being processed, the opening in the wall can be closed with an overhead door. The outside portion of the roller conveyor is coated with a special corrosion resistant paint. After a magnetic crane has placed the parts onto the roller conveyor, they pass through a blow-off station - also placed outside - which removes loose dirt, water and snow from the parts surface, before the parts enter the building. This blow-off station is equipped with special sensors for automatic height adjustment of the air nozzles. A pre-heater, placed in front of the blast chamber, melts and evaporates ice that may cover the parts during winter, and at the same time it heats up the parts to an optimum operating temperature. Inside the building the RRB system is equipped with a cross conveyor designed as a walking beam ("lift and go") that allows the loading of parts onto the roller conveyor from the side.
High media flow of 500 kg/min ensures high blast performance
Taking into account the SMSD GmbH requirement for an increased material throughput the 34/6-HD is equipped with 8 EVO 38 blast wheels with a power of 37 kW each. These blast wheels allow a media flow of up to 500 kg/min, thus producing a surface cleanliness of SA 2,5 at higher parts travel speeds. Explains Norbert Gärtner, plant manager at the Zeithain facility: "We had planned for such a high capacity which, of course, made the higher throughput speeds an absolute must". Major feature of the new EVO blast wheels is their highly robust, wear resistant design that guarantees high uptimes combined with low maintenance costs. This was achieved by the use of wear resistant materials like heat treated manganese and tool steel and an extremely precise wheel housing design made possible by the use of high tech laser cutting technologies. A simple slide-in self-locking blade fastening system eliminates the need for fast wearing parts like locking screws and springs. This allows easy and quick change of the throwing blades. The EVO blast wheels are optimally placed at the so-called "de-scaling angle" on top and at the bottom of the blast chamber which is equipped with easy to replace, wear resistant and gap-free mounted manganese wear liners. Of course, it goes without saying that the blast chamber itself is also made from wear resistant manganese steel ensuring a longer life and requiring less maintenance than blast chambers made from mild steel.
For cleaning of the blast media the RRB is equipped with an extra wide air wash separator. This ensures the optimum cleaning of the high blast media quantities handled by the system. The exhaust air from the blast chamber is cleaned in a dust collector placed on top of the shot blast machine. Compared to dust collectors placed alongside the shot blast machine, this "backpack" concept not only reduces the overall space requirements by 12 square meters but is also more cost efficient. An additional fine filter allows recirculation of the cleaned air back into the building.
Shot blasting in "forward" and "reverse"
Explains the plant manager: "In the smaller RRB system we blast-clean about 100 different components which after flame cutting require a special edge treatment, thermal treatment or annealing. This requires the removal of scale and slag residues from the flame cutting process, and the surface must have a cleanliness of SA 2,5." These requirements are fully met by the RRB 16/5 equipped with four blast wheels, type Hurricane H 42 with a power of 15 kW each.
When planning the location of the shot blast machine in the new building Salzgitter Mannesmann Stahlhandel placed special emphasis on optimized material flow. For this reason the shot blaster was placed in the middle of the two building bays below the bridge cranes. "This placement allows us processing of parts, namely loading & blasting, from both sides of the roller conveyors", explains Norbert Gärtner. That is why the RRB shot blast system is equipped with two blow-off/brush-off cleaning systems placed to the left and right of the blast chamber. These cleaning systems remove residual blast media from the parts when coming out of the blast chamber. They are equipped with special sensors allowing automatic adjustment of their height to the height of the work pieces. Below the inlet and outlet roller conveyors are special media collecting hoppers transferring the blast media back into the media recycling system.
Modular equipment design
Like at SMSD GmbH the modular standard RRB equipment concept – laid out for the processing of parts up to 5,200 mm (205") wide and 600 mm (24") high – makes it possible to meet the most stringent technical customer requirements. Roller conveyor shot blast systems of the type RRB from Rösler are also utilized with great success in other industries like steel fabrication, equipment & machinery manufacturing, ship building and manufacture of wind power generating systems. In wind power applications the RRB systems are used for shot blasting of the steel sheets required for the fabrication of the towers for off-shore and land based windmills.