Method of and instrument for measuring roll diameter in roll grinder

An apparatus for measuring a roll diameter of a roll mounted on a roll grinder having a carriage so as to reciprocate in the axial direction of said roll, a grinding wheel head mounted on said carriage and a work mounting bed for mounting said roll thereon, said apparatus comprising:

• roll diameter measuring means for measuring said roll diameter of said roll, said roll diameter measuring means being mounted on said carriage and having movable gauge heads;
• a step-shaped conical master roll arranged in alignment with a center axis of said roll mounted on said work mounting bed, said master roll having a plurality of diametrical parts of which diameters are different from each other;
• standard diameter value storing means for storing standard diameter value of said diametrical parts, said standard diameter value being obtained by measuring respective diameters of said diametrical parts of said master roll under a condition of a predetermined temperature;
• and
• roll diameter measurement correcting means for calculating a difference between a diameter value of one of said diametrical parts, of which standard diameter value is closest to said roll diameter value of said roll, measured by said roll diameter measuring means and said standard diameter value stored in said standard diameter storing means as a correction value, and correcting said roll diameter value of said roll, which is measured by said roll diameter measuring means, by said correction value.