Own development model for Integrated Management of Technological Innovation.
New grinding machine for the automated manufacture of curved couplings for the aeronautical sector
Development of a new grinding machine for the manufacture of curved couplings. The differential feature on this machine is improved accuracy and built-in in-process measurement systems of the part and wheel geometry to ensure a fully automated process. This new product meets the need of the aeronautical market for universal grinding machines for machining curvic couplings.
Curvic couplings are components with a toothed connection, with a particular geometry that provides them with extraordinary self-centring features. They offer very high precision, maximum load capacity and manufacturing speed, and are most typically used in turbine rotors and aircraft compressors.
It is viable to use them on universal grinding machines for machining these aeronautical components, which previously required a dedicated machine.
The main challenge of the project is to develop a grinding process of curvic couplings adapting a DANOBAT HG horizontal grinding machine.
The HG is a machine optimised for cylindrical grinding, with high stability and precision, and which incorporates an in-process diameter measurement system to ensure maximum accuracy. This measurement system cannot be applied to the machining of curvic couplings, so new solutions are needed to ensure the accuracy required in their manufacture. Furthermore, it being a larger and universal grinding machine, the thermal stability and geometric accuracy are necessarily somewhat lower than those of specialized machines and show a more compact architecture such as those commonly used for machining these couplings. Thermal monitoring of the machine and an improvement of optimised cooling of the machine and the process by means of customised nozzles is proposed, considering additive manufacturing for this purpose.
The technological development to provide an HG grinding machine with the necessary grinding precision for curvic couplings can be broken down into two fundamental tasks: to improve the geometric precision and thermal stability of the machine, and to implement an automated control of process precision. The focus of this project lies on geometric and thermal areas. The critical geometrical errors in the machining process of curvic couplings are those that affect the distance between centres and the parallelism of workpiece and wheel head. The U-CURVIC idea focusses on minimising these two errors by means of two different solutions: improving the precision of the linear axes of a grinding machine, and integrating an ultra-fine adjustment system on the machine of the direction and vertical position of the grinding head, which does not have a linear axis.
In order to automate process control, we suggest measuring the resulting geometry of the part by means of an inbuilt two-dimensional laser profilometer (laser triangulation) which measures the ground profile in an automated way. Processing of data by means of intelligent functions will provide both possible errors in the machined geometry and the remaining grinding depth. If errors are detected in the geometry, the grinding wheel measurement process will be activated to verify and, if necessary, correct the profile of the wheel by diamond dressing.
Implementation on a DANOBAT HG grinding machine with different technological solutions to improve precision and thermal stability. Manufacture of curvic couplings that meet the precision tolerances required by the aeronautical sector.
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