Method for measuring abrasion in a grinding operation and apparatus therefor

In a grinding operation a method of measuring the abrasion depth of at least one outer surface of a substantially stationary body such as a tool which rests in working position against a rotating body for example a rotating workpiece such as a shaft to be ground, comprising the steps of

• moving a measurement pin in a first direction D in a measurement sleeve, which sleeve is arranged in the stationary body, by the shaft into a starting position by pressing on one end of the measurement pin, said measurement pin defines a length L, W in said starting position, such that another end of the measurement pin is spaced apart from an electric contact disposed inside the sleeve,
• during the grinding operation, as a result of the abrasion on said surface of the stationary body, on said one end of said measurement pin and on said sleeve, by the shaft pressing on said surface, on said one end of the measurement pin and on said sleeve, continuously further moving the measurement pin in the first direction in the sleeve such that upon traversing a distance (cf. W1), the latter distance being predetermined such that it is traversed when the surface of the stationary body has been completely abraded to a predetermined amount so as to be required to be replaced, said another end of the measurement pin contacts against the electric contact so as to provide an alarm via an electric circuit of an indicating device, and
• measuring the abrasion on said one end of said measurement pin, comprising the steps of
• storing in a path detection system a desired reference length B of an end length (cf. 13) of the measurement pin,
• before a start of a new grinding operation removing the shaft from contacting the stationary body and said measurement pin and moving the measurement pin back in a second direction opposite to said first direction so that said end length moves past stationary measurement feelers which are arranged laterally on the measurement sleeve and are operatively connected with the path detection system, and measuring and comparing the end length (13) of the measurement pin, which end length has moved past the measurement feelers in said second direction, with the desired reference length B stored in the path detection system, and
• initiating an alarm signal if the measured end length (13) of the measurement pin is at most the same as the stored desired reference length B.