TCD (Total Cost of Design) and TCM (Total Cost of Manufacturing) are essential factors in maintaining a leading position in high-demand and competitive machine-tool markets worldwide. With one eye on the costs and the other on performance level, most of the machine-tool leaders have switched to the cubic concept, invented and developed by Redex to enhance axis drives.
The cubic concept entails that the machine frame on which the axis drives (mostly with Rack & Pinion planetary reducers inside) are fitted is no longer part of the machine, but part of the drive itself. This design offers numerous advantages, such as eliminating the need to design and integrate high-precision fixation extensions to the main machine frame. This key benefit simplifies the design, saving many hours of stiffness simulation on sophisticated 3D CAD software and even more on real test proof campaigns. The implementation process is also streamlined, with only very simple machining shapes for the fixation interfaces needed. This advantage increases global savings on TCD and TCM by 15 to 20 per cent, in contrast with conventional approaches.
This cubic process used to produce the DRPng and KRPXng product lines. The core component of Redex's axis drives is a very low backlash / very high stiffness planetary reducer, fully embedded in its own cubic frame and ready to be fitted to the machine mainframe exactly as if it were a part of the frame itself.
Now available in the five standard universal sizes (the full range - size 1 to size 5 - will be officially introduced at the EMO), KRPXng is a compact single drive, especially designed for the easy construction of 100 per cent backlash-free axis drive systems (becoming a dual drive when used together with an electric preload). This design offers a significant implementation advantage with the pinion height not higher than 75.9-135mm.
Also available in the five standard universal sizes, DRPng is a DualDrive developed option which combines two planetary reducers inside the same compact and ultra-high stiffness cubic housing unit. Cubic design of the DRP series even allows 100 per cent backlash cancellation through a cost-effective mechanical preload arrangement and simplifies the setting-up process when an electric preload system is utilised.
Each machine subassembly and component must keep the global stiffness at the same level as the main frame, to avoid deterioration of global dynamic performance. The substantial stiffness of DRP & KRPX series is a result of the patented Redex integral output pinion design with oversized output bearing. The output pinions are machined to the same diameter as the shafts, giving the optimum balance between transmissible torque and rigidity at the rack. The output bearing consists of two preloaded and substantially oversized angular contact roller bearings. This construction enables the bearing to support the pinion as close as possible to the force, as only the thickness of the fastening nut separates the pinion from the output bearing. This design considerably reduces radial bending, which is responsible for 60 per cent of overall distortion that is still poorly managed by existing systems.
The housings structures have been optimised with FEM analysis methods to avoid deflection during acceleration. The fixture is made to ensure a still connection with the machine frame. This smart system has been designed to eliminate the risk of mounting system deflection. The result is an increased dynamic working range, leading to the ability to displace heavier loads at higher speeds. Its performance in terms of stiffness combined with its low inertia enable higher accelerations (up to 25m/s2). Consequently, the natural frequencies of the axis drive systems, in which the new series are embedded, are significantly improved.
Redex engineers have taken a further step forward, introducing a new gear-finishing technology to the machine tool industry. This new technology, HQ-GF, ensures high reversibility, significant noise reduction, and above all, a decrease of over 15 per cent of power losses. Thousands of kWh can be saved in over a machine's lifetime.
With the HQ-GF inside, the new technology applied to DRP and KRP series is joining the long line of REDEX 's innovative products specifically designed by its engineering team to constantly improve machine-tool performance.
For further information about axis drives and the cubic concept, please visit www.andantex.co.uk.