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Turbine shafts Shafts of power plant turbine with diameters up to 1200 mm and length up to 16 m have a plurality of circumferential grooves with depth up to 400 mm and width from 90 mm onwards. These grooves cause a severe notch effect. The root radii range from 20 to 80 mm to reduce the notch effect. But this measure is not good enough to avoid material fatigue. The deep rolling process is specified for the rood diameter, the radii and the groove flanks as well. A slim mechanical system has been designed, consisting of a spring body with leaf springs. The infeed motion of the turret is used to control and reproduce build up of the rolling force. ECOROLL® offers these tools as FAK90 and FAK120 with different roller diameters. Two systems for rolling force measurement are available:
The rolling force is determined by means of the force/deflection characteristics of the spring pack in both cases. 
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Turbine wheels The face contours of steam-turbine-wheels experience high tensile stresses under rotation, caused by centrifugal forces. If this happens under chemical contaminated steam, stress corrosion can induce fatigue crack suddenly. Residual compressive stresses in the surface layer, generated by deep rolling with the ECOROLL® "ballpoint" tool HG13 eliminates or strongly reduces this danger. The process is applied in one setting after the turning on the vertical lathe. The tool can be set to different angles. The hydraulic unit of the tool is connected to the machine control for CNC control start and stopped off the deep rolling process. This determines exactly the stretch of the deep rolled zones. Cooling pumps  Coolant pumps of nuclear power plants are very important for their safety. Critical fillets and grooves on pump shafts and stator wheels are deep rolled with ECOROLL® tools. The picture shows a layout of tool positions and deep rolling areas of the stator wheel. |
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