With its HDDS series mechanical expanding sleeve mandrel, RINGSPANN provides mechanical engineers and users in the field of gearing technology with a highly efficient alternative to hydraulic expansion technology. HDDS enables high precision and flexibility in fine machining to be achieved and supports the implementation of fully automated manufacturing concepts.
For all manufacturers of gear cutting machines and users in the field of fine machining who have particularly high demands on the precision and flexibility of their clamping fixtures, RINGSPANN has a solution: the mechanical expanding sleeve mandrel HDDS. As an alternative to hydraulic expanding fixtures, it features a comparably high concentricity of ≤ 5 µm with a surprisingly great expansion. While the first manufacturers are testing the patented HDDS as a potential standard component in their gear cutting machines, RINGSPANN is also positioning it as a component for simplified entry into automated production.
High geometric accuracy requires special clamping fixtures
The mechanical production of high-quality spur and bevel gears for use in gear manufacturing has been characterised for years by increasing demands on their geometric accuracy. For a long time, customers in the sector of fine machining were satisfied with gear qualities of 8 or 9 according to DIN 3961, but today suppliers are usually required to achieve qualities of level 7 or 6. In the field of motor racing, in particular, gear qualities of at least 5 or 4 are the gold standard. Yet every experienced gear manufacturer knows that such high accuracies cannot be achieved without specially designed clamping fixtures. This challenge drove the development of the HDDS expanding sleeve mandrel.
Leakage-free clamping ensures process reliability
As a mechanical internal clamping system, the HDDS is a real highlight of modern clamping technology. It features a concentricity of ≤ 5 µm, offers an absolute expansion four times greater than that of most hydraulic clamping fixtures, and is therefore currently regarded as one of the best mechanical alternatives to the hydraulic expanding mandrels often found in gearing technology. HDDS accommodates workpieces with bores up to tolerance class IT10, while most hydraulic clamping fixtures are only suitable for accommodating workpiece bores up to tolerance class IT7. Unlike hydraulic expanding clamping fixtures, HDDS is also free of any leakage risks, its use increases process reliability in series production, where even the smallest leakage on hydraulic clamping fixtures triggers the need for repair. The only source of wear on RINGSPANN’s HDDS is its clamping discs. High performance capability in high precision gear grinding HDDS proved its performance capability and power reserves during high-precision cylindrical gear grinding in the production of a Swiss gear manufacturer. Here, its axial and radial run-out accuracy were measured both with a control workpiece on a tactile measuring device and with an original blank in a coordinate measuring system. The results were even better than expected: The measuring equipment recorded accuracies of ≤ 2 µm for the axial runout and ≤ 3 µm for the radial runout. In addition, the geometric accuracy achieved for the involute toothing on the series workpiece was well within the defined tolerance limits and thus well above the customer’s requirements.
High flexibility thanks to the high expansion rate
Other practical cases have since shown that the expanding sleeve mandrel from RINGSPANN not only enables the achievement of high gearing qualities, but that it also supports the realisation of fully automated manufacturing concepts: since hydraulic expanding mandrels have only a low expansion rate due to their physics, high-precision handling systems are usually needed to feed them, which also drives up the costs for the required measurement and control technology for the periphery. The HDDS from RINGSPANN, on the other hand, has an expansion that is four times greater than that of many hydraulic clamping fixtures. Due to the high expansion rate, the technical expenditure for the entire periphery is considerably reduced, which makes the entry into fully automated machining much easier. RINGSPANN’s mechanical expanding sleeve mandrel is capable – depending on the version – of clamping bores with diameters from 25 mm and is also suitable for bores whose internal geometry is interrupted by a groove. In addition, it can also be used to machine components with very short clamping lengths, because its mechanics provide a pull-back action in which the workpiece is pressed against a contact and aligned at the same time. Besides, in high-precision machining, further advantages can be achieved by using a spindle sleeve because this increases the reproducibility of the clamping result to ≤ 2 µm – while simultaneously increasing the rigidity of the entire system. This also means that the clamping system is insensitive to very large radial forces applied by the tools.