DUSTPROOF DEVICE IN OUTSIDE DIAMETER MEASURING APPARATUS

摘要

PURPOSE:To measure smoothly the outside diameter of an object to be measured without being hindered by a scale by a constitution wherein a tapered protective tubular member is provided in a passage of an outside-diameter measuring apparatus through which the object passes and sensors for measuring the outside diameter of said object are provided outside the protective tubular member. CONSTITUTION:A protective tubular member 10 tapered toward the side of a hollow shaft member 3 (toward the inside of a passage 9) is provided in the passage 9 on the side of a hollow disk member 2. The large-diameter part 10a of the protective tubular member 10 is fixed on the other side surface 2c of the hollow disk member 2, while the small-diameter part 10b thereof is fixed to the passage 9 on the side of the hollow shaft member 3. Moreover, two sets of sensors for measuring the outside diameter, each of which comprises a detector 11 and a parallel-light source device 12, are arrnged inside the hollow disk member 2. The sensors are protected from a scale by the protective tubular member according to the aforesaid constitution, and thus the measurement of the outside diameter can be performed smoothly without being hindered by the scale.