US 5,694,339 AGranted

Roundness measuring apparatus

AssigneeMitutoyo Corporation

InventorsTakao Ishitoya, Yoshiyuki Omori, Tsukasa Kojima

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Abstract

An object is mounted and rotated on a rotary table. An encoder outputs a rotary angle signal corresponding to the rotary angle of the rotary table. A detection head outputs a displacement detection signal while tracing the surface of the object. The detection head moves within a plane including the axis of rotation, so as to oppose the outer or inner surface of the object. When the detection head is opposed to the inner surface of the object, the positive and negative signs of the displacement detection signal is reversed, while at the same time a 180.degree. angle is added to the rotary angle signal. By utilizing the reversed displacement detection signal and the corrected angle correction signal, the obtained result can be displayed through a displaying processing common to the processing for the outer surface.

Claims8

Dependent claims

A roundness measuring apparatus, comprising:

a rotary table for mounting an object having continuous inner and outer surfaces around an axis of measurement;
an encoder for outputting a rotary angle signal corresponding to a rotary angle of the rotary table;
a detection head for detecting a displacement from a detection reference along a peculiar detection direction having positive and negative directions with respect to a peculiar detection reference, to thereby output a displacement detection signal corresponding to the displacement in response to an output of the rotary angle signal;
R axis guiding means for guiding the detection head along a straight line passing through the axis of measurement;
polarity reversing means for reversing positive and negative signs of the displacement detection signal when the detection head is opposed to the inner surface of the object along the straight line;
and
angle correction means for introducing a 180.degree. correction angle to the rotary angle signal when the polarity reversing means reverses the positive and negative signs so as to generate a corrected angle signal, wherein
a form of the outer and inner surfaces of the object is measured while retaining the peculiar detection direction.

5 more elements

Dependencies are inferred from the claim text.