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Florenz-Allee 1, 55129 Mainz, Germany
Tel: +49 6131 / 4998-0, Fax: +49 6131 / 4998-109
Multi-passage rotating unions—a solution for complex tasks
In the machine tool, the task of transferring more than just one medium into/from or through a rotating machine part is becoming ever more frequent during machining. The requirement results from both turning and milling operations as well as from combined lathing and milling operations and includes all the machining axes. DEUBLIN, the rotating union manufacturer, unveiled a new generation of multi-passage rotating unions—the Hybrid series—at the AMB trade fair for this very purpose.
As a two-channel rotating union, this product group has already been in use for a considerable amount of time, particularly in the field of clamping technology and for cooling with hydraulic, compressed air and coolant media. The tried-and-tested 2620 series, which the manufacturer has been a preferred supplier of for a number of years now, is a good example of this.
But in spite of this, the company has set about creating a new development, since user requirements are becoming ever more complex nowadays. Rotational speeds of more than 10,000 rpm are therefore already being achieved in the two-channel segment; however, users and design engineers are also currently requesting rotational speeds of 5,000 rpm and higher in the multi-passage segment of three channels and more—with pressures of up to 250 bar for hydraulics or up to 10 bar for compressed air at the same time, even under rotating conditions.
The applications are vast and varied in this regard. While requests do indeed come from the clamping technology segment with regard to machining, machine manufacturers are increasingly requesting complex multi-passage rotating unions too. DEUBLIN has set itself the task of also being a provider of ideas for new possibilities in the machining process with its rotating unions. Media supply operations, which previously could only be performed at a standstill or at a low rotational speed, can now take place at maximum rotational speed. This technological leap increases the degree of automation and thus the productivity of the overall system.
What made this technological leap possible was the fact that sealing technologies—whether the mechanical seal, the hydrostatic seal or the elastomer, say “plastomer” seal—are combined in the new Hybrid series. This combination means that user requirements with respect to media, operating parameters and process parameters can be responded to with pinpoint accuracy. The most suitable sealing technology is used for each media channel on this basis. All three sealing technologies can even be combined in a single housing if necessary.
To achieve this goal, a joint discussion is held between the manufacturer and the user to specify the necessary media and operating data. It is also very important to find out about the processes—when which medium is pressurised, for instance. DEUBLIN, as a specialist when it comes to selecting the right sealing technology, designs an application-specific solution on this basis. Depending on requirements, the rotating union may then include a single sealing technology, but could even include all three sealing technologies too!
Target criteria influence the selection of the suitable sealing technology, whereby extending a rotating union’s service life often takes priority. But the influence of temperature on the overall system, for example, is decisive too. The job of contemporary solutions is to demonstrate excellent values in both disciplines—in other words, long service lives with low temperature development.
At DEUBLIN, design engineers and users will find a large selection of existing rotating unions for multi-passage applications that are already ideal as a technical basis and simply “fit in” straight away in many cases. Existing series can also be adapted to the special requirements. And, last but not least, modular series are available too. Against this backdrop, the user receives an extensive “kit” to find sufficient solutions.
A current example: A tooling machine manufacturer decided to design and produce their very own tables for simultaneous milling / turning work for rotational speeds of 20 rpm to 1,000 rpm. Rotating unions for three to ten channels were needed for this purpose. Depending on the table user’s requirements, hydraulics or pneumatics for clamping and un-clamping loosening functions are required both at a standstill and under rotating conditions. Added to this are functions such as system control or table cleaning with coolant or compressed air. Channels for a vacuum can be implemented too.
Based on a standardised interface, a solution that is consistent for all variants was developed for this purpose. The particular advantage lies in the fact that the specification of the actual number of channels does not have any influence on the interface. The machine manufacturer is thus able to respond to any changes in channel assignment in a flexible manner. DEUBLIN has thereby enabled a simplified basic design for the table series.
Additional advantages—such as greater productivity and the integration of various functions under rotating conditions—can be achieved for turning and milling companies.
This applies both to pure rotation, where the rotating union supplies media to the workpiece spindle and any adapters, and to milling and turning operations, where the rotating union supplies media to the pallet and workpiece clamps. Here, the rotational speed and thus the cutting speed can be increased with the Hybrid series. What’s more, the Hybrid series can also be used to implement a variety of turntable application functions, such as clamping and un-clamping functions, system control and table cleaning at rotational speeds of more than 1,000 rpm.
Since these functions are integrated in a compact manner, additional scope for efficiency and productivity enhancements is created for both machine manufacturers and users alike.
Co-Authors: Frank Reimold, Vertriebsleiter Deutschland, DEUBLIN GmbH
Jörn Jacobs, Dipl.-Kfm., Fachjournalist, IHW Marketing GmbH