in Vol. 3 - May Issue - Year 2002
Linear Continuous Flow Machines - Continuous Vibratory Finishing for Large Components
The process chamber of the linear continuous flow machine type R850/4600 is designed in such a way that components of up to a diagonal dimension of 600mm can be vibratory finished fully automatically.
Linear continuous flow machine, pictured here in soundproof cabin with loading device and belt drier
Recirculation installation for clarifying process water
A process water recirculation system enables up to 95 percent of the fresh water and cleaning compounds to be reused.
Rösler Oberflächentechnik GmbH is an international leading all-round supplier of surface finishing and shot blasting systems located in Memmelsdorf and Hausen, Germany. Besides the two German plants the Rösler Group has ten branches and over 50 representations worldwide. The manufacturing programme also includes the media (chips + compounds) for the surface finishing as well as process technology and environmental technology (recycling, processing, recycling of waste and process water + high-performance centrifuges).
With this new type of continuous flow machine by Rösler Oberflächentechnik even very sensitive large components can be vibratory finished economically and gently. The automatic linear continuous machine with a working width of 850 mm, which is unique on the market, makes it possible to treat components up to a diagonal dimension of 600 mm and up to 50 kg in weight without difficulties. Being linked to a process water recirculation unit, the whole facility can be integrated directly into the production process.
While fully automatic vibratory finishing is almost standard for small components and mass-produced products, production planners very often still rely on the manually operated trough-type vibratory machines for large components. But manual loading and unloading complex exchange of abrasives and subsequent component rinsing does not only cost precious time and thus productivity but the quality is not consistent and not easily traceable. However, today ever more competitive market conditions demand a clear increase in productivity and the prerequisite for increased demands on quality is that the production processes are absolutely faultless in all parts and are absolutely reproducible from part A to part Z. For this reason, automatic treatment solutions are now moving into the focal point of production planning also for surface treatment of large components.
The argument that large parts with dimensions over 500 mm cannot be economically vibratory finished has been successfully disproved by Rösler Oberflächentechnik with the newly developed linear continuous flow machines type R 850/4600 DA and R 850/6600. With a working width of 850 mm and a total working length of the working chamber of 4600 mm and 6600 mm, respectively, these machines ensure an exceptionally economic treatment of consistent quality of components with a diagonal dimension of up to 600 mm and a weight of up to 50 kg.
Integrated in the Production Process
Linked to a process water recirculation installation system type R 850/4600 DA, this system has been integrated in the production process at one of Rösler's customers for some time now. Here it replaced a six year old trough-type vibrator in which components with a size of 650 mm x 390 mm were vibratory finished after the metal removal process with a great amount of handling. The components had to be loaded, unloaded and passed onto subsequent cleaning processes manually. These were operations where not only valuable time was lost but afforded potential for quality suffered because the time in the process chamber - an important prerequisite for the intensity and quality of processing - was controlled at the discretion of the operator alone.
In contrast the user of the automatic linear continuous flow machine now profits from a series of advantages:
-Time-saving due to simple handling
-Fully automatic flow of processing
-A treatment quality which is exact from the very first to the very last part - as previously determined
The safety distance to be selected in cycles ensures that the parts to not come into contact with each other in any way.
The components (e.g. chilled cast parts, steel cast parts) are delivered after the metal removal process on pallets directly to the production island to the continuous flow machine. One operator takes the components either by hand or by means of a crane or lifting truck and puts them onto the transport conveyor, which operates in cycles (depending on the size of the components 20/30/60 secs.). From there the components are conveyed by means of a special lifting device to the height of the unit, configured to 90 degrees and then placed fully automatically on a connected inlet conveyor belt which finally transfers the components into the process chamber of the continuous flow machine.
High Level of Precision of Treatment
The continuous flow machine uses plastic bonded abrasives (chips) for the treatment. The special shape of the inner surface of the process chamber ensures optimum rotation of chips and components and thus an excellent treatment performance. Sticking and climbing up of the components on the process chamber walls is prevented. The flow-through time can be set using the process chamber inclination, the counterbalance and speed for the treatment of the components mentioned above, on average 8-10 minutes. Sensors monitor the variable inclination position of the process chamber.
The separation of abrasives and component is effected with a large external separating unit with revolving steps. Simultaneously the abrasives, which have become too small are separated as they could block certain bores. This is effected with a calibration screen.
After the separation process the lateral vibration conveyor transports the chips. Residual water and component burrs are removed via the replaceable sieve segment section. Incline conveyor for returning chips is effected by a wide transport belt equipped with edge studs and carriers. Another vibratory conveyor transfers the chips and conveys them back into the process chamber. After vibratory finishing the components only require washing, drying and assembling.
A pre-programmed control unit (SPC)
programs and monitors the processing times, processing speeds and inlet cycles so that only the required processing cycle runs.
Increased Potential for Cost Savings due to Recirculation System
A process water recirculation system (centrifuge) is linked to the continuous flow machine. Process water clarification is another important step in order to make processing more economical. This enables up to 95 percent of the fresh water and cleaning compounds to be reused. The useful life of the process fluids can be up to several months depending on different factors.
The water coming from the vibratory finishing machine is continually intermediately stored in a wastewater holding tank and subsequently pumped into the centrifuge. Solid material/liquid separation takes place here at almost 3000 revolutions. Due to the high acceleration of up to 2000 g, the suspended material in the vibratory finishing wastewater is deposited on the rotor interior. The compact sludge created is automatically scraped off by an integrated scraper knife and gravitates out of the rotation drum open at the bottom into a sludge wagon placed under the unit.
The clarified water is forced out of the centrifuge rotor at high speed through a scraper pipe into a clarified water reservoir and fed back to the vibratory finishing unit from there. An SPC controls the centrifuge so that filling and scraping times can be set depending on the consistency and degree of sludge.
Today it can be assumed that more than 90 percent of all vibratory finishing processes can be operated with environmental centrifugal technology. Precise balancing of the treatment materials (compounds) is of great importance in this.
For this reason Rösler is one of the few manufacturers to always provide its customers with complete process technology which is specifically adapted to the needs of the individual customer consisting of plant construction, process water clarification system, abrasives and compounds from one source.
Rösler Oberflächentechnik GmbH
Vorstadt 1, D-96190 Untermerzbach
Tel: +49 (0) 9533 / 924 - 0
Fax: +49 (0) 9533 / 924 - 300