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production pelton runner

 

Apart from the customary fulfilment of check-lists separated for pre-design and detail construction, every single runner is put in order as part of a continuously variable construction series according to it's hydraulic data and it's special geometric proportions.
A runner is designed by means of an arithmetic programme as a function of the specific speed of nq, the head H and a typical measurement e.g. pitch circle
diameter D.

The sum of all hydraulic and mechanical strength-related experimental data and experiences have gone into this parametric arithmetical programme, which gives out all bucket contours and cutting edge geometries as parallel sections.

Furthermore, the calculation programme, which is symbolized in illustration 1, determines all compressive loads per unit area and mechanical stresses.

Diverging interventions into the programme for reasons of adaptation, e.g. to given turbine case contours for replacement runners, are also easily possible.
The actual results of the calculation programme are the special coordinates of the parallel sections and the broad outlines which go with them.
These coordinates in the form of tables are transformed into a 3D-network diagram (illustration 2).

This network diagram is overlied by a functional surface area programme. Ensuingly, a CNC-processing programme for the machine tool, which is used for milling the spatial contours of a Pelton bucket, is drawn up. The 3D-model (illustration 3) of a bucket as a basis facilitates both milling the runner blades themselves as well as producing a drop outline for the forged buckets and, furthermore, possibly milling a model runner on a suitable scale for a laboratory acceptance test.

The individual buckets are processed on CNC-machines. The bucket is simply put up with 2 clampings, thereby making an entire processing of the bucket possible.

This open accessibility on all sides allows the use of chiefly short and very stiff tools in the processing machinery, thereby making high cutting speeds combined with very high surface qualities realisable in the best way possible.
In addition, processing can be done with customary tools and does not require special tools.
Illustration 4 shows the processing of the pedestal foot and illustration 5 the processing of the inside of a bucket with an inside width of 490 mm and an untreated single weight of 250 kg.

The advantages of a small-series production in the production cycle can be made use of in an optimal way through electronic data processed and edited programming as well as mechanical processing of the buckets.

 


illustration 1


illustration 2


illustration 3


illustration 4


illustration 5

Our Partners:    
Metzler - Dimensionen der Metallbearbeitung MIKRON WESTCAM
 
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