Grinding of pelton buckets
For efficiency reasons Pelton buckets must have a very smooth surfaces. Since machining of smooth bent surfaces is very time consuming and costly the grinding is still done manually.
The goal is to have a robot doing the major part of the work. For this task a grinding disk is attached to the robot arm with an additional extension in between. The compact design of this construction allows the robot to grind even in places which are very difficult to reach. The grinding paper is attached to the disc via a Velcro fastener which allows to exchange the abradant automatically. An integrated force control tells how much the grinding disk is used up and if it already has to be exchanged.
Besides the savings in time and costs the automatic grinding also gives more precise results. With the force control the grinding pressure can be controlled. Further more this device allows to measure the resulting geometry with high precision. If the resulting geometry is outside of the tolerances the speed of grinding can be adjusted to make sure the required shape is generated.