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Hybrid four-point method
Roundness measure which measures correctly
The traditional measuring devices on grinding machines contain only a two-point measuring system. The traditional two-point method cannot distinguish the roll's rotation line of the roll's roundness profile. Therefore a tape is seen as two when using a two-point system (see a figure down on left). It is not possible to measure odd waveforms correctly with any two-point measuring equipment. (See figure down on right). Only a cast and a diameter profile can be measured with the traditional methods of measuring. This simply means that the roundness cannot be measured properly with the traditional measuring methods.
The C-frame type can be either saddle or rigid.
Without a real many-point measuring method a true result cannot be provided. Due to this a good grinding result cannot be achieved.
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| A tape measuring carried out with the 3D four-point method (see left) and with the two-point measuring device (see right). |
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A triangular roll measured with the 3D four-point method (see left) and with the two-point measuring device (see right). |
The measuring frame (C-frame) can be of a rigid (a) or of a saddle type (b) (below).
Why does the two-point method measure wrong?
We can see the answer from the figure below. The two-point diameter method sees a profile with odd lobes as round, because it's diameter variation is zero.
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