| 摘要 |
PURPOSE: A variable mandrel for measuring an inner diameter is provided to freely retracted according to a deformation degree of an inner diameter of a tube way while passing the tube, and maintain an original size after passing through the tube, thereby measuring a minimum diameter of the tube way. CONSTITUTION: A variable mandrel for measuring an inner diameter includes a cylindrical main body(10) having a minimum diameter able to maintain and connection rings(11) at both front and rear parts to connect a passing line(2), a plurality of variable wings(20) rotatable with respect to the main body, expanded from a front end of the main body with a predetermined inclination to become parallel to a side of the main body, extended backward of the main body and having guide grooves formed with holding protrusions at both end parts of an inner peripheral surface, and connection plates(30) positioned between the variable wings to be fitted into the guide grooves and having coupling protrusion at a surface correspondingly to the holding protrusions of the variable wings.
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