Processing diameter measurement device with grinder measurement malfunction assessment function

An in-process diameter measuring apparatus equipped with a function of determining a measurement abnormality of a grinding machine, the grinding machine including:

• a workpiece support mechanism to support a workpiece of a circular shape in section and to rotate the workpiece about a center axis;
• a grindstone drive mechanism to grind a to-be-processed surface using a grindstone, the to-be-processed surface including an inner peripheral surface or an outer peripheral surface of the workpiece;
• and
• a control device configured to control the workpiece support mechanism and the grindstone drive mechanism,
• the apparatus measuring the diameter of the to-be-processed surface of the workpiece during the process of the workpiece, and the apparatus comprising:
• a sizing device to include a plurality of measuring heads that contact a plurality of respective circumferential locations of the to-be-processed surface, the plurality of circumferential locations including at least two locations spaced apart from each other in a diametric direction of the to-be-processed surface of the workpiece, and to measure respective diametric positions of the locations which the heads contact;
• a dimension calculator configured to calculate the diameter of the to-be-processed surface based on measured values of the plurality of the measuring heads of the sizing device;
• and
• a measurement abnormality determiner configured to determine a difference between measured values of the two measuring head out of the plurality of the measuring heads, the measuring heads measuring respective positions of the respective two locations of the to-be-processed surface that are spaced apart from each other in a diametric direction, and to determine the occurrence of a measurement abnormality in the event that the difference departs from a predetermined permissible range.