AUTOMATED FINISHING SYSTEM REMOVES OXIDATION FROM TURBO-GENERATOR COPPER ROTOR COILS
Installation of an automated surface-finishing system with a pair of custom-built Hodge Clemco blast cabinets has significantly improved production of rotor coils for turbo-generators at the Loughborough factory of Brush Electrical Machines.
Brush is the world’s largest independent manufacturer of generators for gas and steam turbine drive, with customers in the power-generation, industrial, marine and off-shore sectors world-wide. The UK factory produces air-cooled DAX two-pole turbo-generators up to 120MVA output.
The copper laminates fitted to the central rotor of each generator are formed from strip typically 30mm x 6mm and have to meet precise specifications to ensure reliable long-term performance. After being cut to length, the strips are bent on edge at 90° at both ends, which has a work-hardening effect, requiring annealing at 700°C. Oxidisation caused by the heat-treatment then has to be removed.
In the past the scale on the copper was removed by staff using powered hand-tools and wearing breathing apparatus in an enclosed area. The process was time-consuming and uncomfortable for the operatives, according to Brush operations engineering manager Peter Williams.
The company has now invested in two Hodge Clemco blast cabinets linked to an automatic feed system designed by Rotary Engineering, which has tripled throughput, improved working conditions and resulted in a better and more consistent finish. As well as the blast cabinets and feed conveyor, the system incorporates abrasive hopper, abrasive cleaning and dust collection equipment in a single integrated unit.
The cabinets use a suction blast system that propels abrasive through 12 nozzles at all four sides of the area on each component where the oxidisation is present. A wide variety of media can be used. Abrasive volume and speed are precisely controllable, and an 1800cfm reclaim unit linked to a dust collector automatically collects used abrasive and grades it for re-use or disposal.