Innovative tub vibrator concept for better quality, higher efficiency and improved competitive standing
, Rösler OberflÀchentechnik GmbH - Retour à l'aperçu
Plastification augers for melting plastic pellets are an essential part of each injection molding machine. To offer equipment that guarantees a maximum of quality and precision in an extremely competitive market, the globally active Engel Austria GmbH produces these augers exclusively at its Austrian manufacturing location in St. Valentin. The investment in two fully automated mass finishing machines from Rösler ensures not only a more cost-efficient production but also consistently high quality. The automation concept allows operating the tub vibrators and directly linked cleaning system with minimal personnel requirements. Since the optimized polishing process helps to substantially reduce the processing times, this trend-setting equipment concept will definitely be useful for other industrial applications.
In cooperation with the Austrian automation specialist Promot Rösler created an integrated system that optimally links the various equipment components. The work piece fixtures, specifically developed for this application, guarantee a maximum of operational efficiency and finishing quality. Moreover, the set-up times were significantly reduced. Last-but-not-least, by expanding the finishing system to two tub vibrators, the capacity for polishing the plastification augers - up to three meters long and 15 to 80 mm wide - was substantially increased.
Automatic loading of the tub vibrators with minimal handling times
The injection molding machinery manufacturer Engel has been using Rösler finishing equipment for more than 20 years. Until recently the company polished the plastification augers in a tub vibrator with a single stage finishing process. This included time-consuming, manual work piece handling requiring a lot of manpower, especially for loading and unloading the work pieces into and from the finishing system. Therefore, the specifications by the customer called for a reduction of the physically demanding handling work for the employees and automatic loading & unloading of the tub vibrators. A key role in this challenging project played the expansion of a gantry crane system by the Austrian automation specialist Promot, which is already successfully employed for loading/unloading the grinding machines used in a preceding finishing operation. Furthermore, the new mass finishing system had to be able to handle the production volume of plastification augers specified by Engel. Based on the already existing polishing process with a cycle time of on average 8.5 hours, this would have required several new tub vibrators.
Two stage process significantly reduces processing times
Therefore, the main focus of the Rösler engineers for this project was the reduction of the processing time and to minimize the required quantity of tub vibrators. Both goals were achieved by utilizing a two-stage Keramo-FinishŸ process that runs simultaneously in two tub vibrators, model R 800/3200 TSD-15. These machines, equipped with special direct-drive vibratory motors, are extremely productive, allow flexible operation and require very little space.
By reducing the overall roughness reading to a value of Ra = < 0.1 ”m the two-stage Keramo-FinishŸ fine-grinding and smoothing operation in the tub vibrators helps to drastically improve the surface finish. This is the main reason for the excellent quality of the plastification augers. The streamlined finishing operation in combination with the powerful equipment helped to substantially reduce the processing times. Of course, the improved surface quality of the work pieces entering the Keramo-FinishŸ process was also a positive factor. This is achieved by using fine grinding media that offers a relatively high metal removal rate but creates a fine surface finish.
Loading of the tub vibrators with a gantry system and optimized setup concept allows a fully automatic polishing operation
To allow fully automatic work piece loading/unloading of the tub vibrators, Rösler developed an automation and control concept for the gantry system in close cooperation with Promot. It transports the plastification augers after the pre-grinding operation to the work piece setup and mounting station. There, an operator places a certain quantity of augers, depending on the auger size, into a mounting frame. Mario Stollnberger, manager of the plastification activities explains: âIn the past this setup operation was very time-consuming, because both ends of every individual auger had to be mounted into the frame separately. Today, this is done by simply placing the augers into the mounting frame utilizing a floating positioning system. This has cut the setup times to around 15 minutes.â In the next step the gantry system picks up the mounting frame, now loaded with work pieces, transports it over the tub vibrator and then lowers it onto special guide rails positioned in the vibrator tub. This clever concept allows the mounting frame with work pieces to freely rotate in the processing media. In addition, it offers the advantage that upon completion of the finishing cycle the entire frame can be fully automatically removed from the tub vibrator. The placement and removal of plastification augers into and from one mounting frame takes place, while the work pieces in another mounting frame are being processed. The simultaneous work piece loading/unloading and processing function further improves the overall efficiency of the polishing process.
Besides the two mass finishing vibrators the new polishing cell includes a work piece load/unload station, a work piece cleaning system that was specifically developed for this application and a fully automatic centrifuge, model Z 1000, for cleaning and recycling the process water in a closed loop and thus, saving valuable natural resources.
Innovative automation concept offers many possibilities
Tub vibrators can be used for numerous finishing applications. However, until now it was practically impossible to automate the work piece loading/unloading operation for these versatile mass finishing machine. With the newly developed, innovative automation concept Rösler has now a solution that will make the finishing operations in other industries, like aerospace, etc., more efficient and faster!
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