A plug gauge includes a housing defining an internal volume and a longitudinal axis AH. The housing includes an opening into the internal volume. The plug gauge also includes a contact element at least partially received in the opening. The plug gauge further includes a plunger at least partially received in the internal volume. The plunger is biased into engagement with the contact element to urge the contact element radially outward from the housing through the opening. The plug gauge additionally includes a sealing member between the contact element and the housing.

The following are observed using a camera: a first position of a small hole of a workpiece, which is fixed to a linear-and-tilting-motion stage and rotating with a rotating body, and a second position thereof different from the first position, at a first rotation angle of the rotating body; and the first position and the second position of the small hole of the workpiece at a second rotation angle different from the first rotation angle of the rotating body. A position and a tilt of the small hole are calculated from coordinates of the respective observed positions, and small hole information, which includes the position and the tilt of the small hole, is outputted.

A gauge apparatus includes a body member, one or more gauge arms biased outwardly from the body member for engagement with a wall of the elongated space, and one or more deformable regions. The gauge apparatus is configured so that a variation in an outward extension of each gauge arm from the body member induces a change in strain in a corresponding one of the one or more deformable regions. A gauge system includes the gauge apparatus and an optical fiber attached to the gauge apparatus so that a strain in each deformable region of the gauge apparatus is transferred to a corresponding sensor portion of the optical fiber. The gauge system may be used for making real-time measurements of a geometry of an elongated space such as a wellbore of an oil and gas well.

A gauge apparatus includes a body member, one or more gauge arms biased outwardly from the body member for engagement with a wall of the elongated space, and one or more deformable regions. The gauge apparatus is configured so that a variation in an outward extension of each gauge arm from the body member induces a change in strain in a corresponding one of the one or more deformable regions. A gauge system includes the gauge apparatus and an optical fiber attached to the gauge apparatus so that a strain in each deformable region of the gauge apparatus is transferred to a corresponding sensor portion of the optical fiber. The gauge system may be used for making real-time measurements of a geometry of an elongated space such as a wellbore of an oil and gas well.

A system and method for measuring an inside diameter of a pipe to determine if it exceeds a predetermined value using a plurality of fingers operatively connected to a spring. When in a fully extended position, the distance between opposite fingers is the predetermined value. The fingers are pivotable between a starting position, through the fully extended position, and to a failing position. In the starting position, an outer end of each finger engages an inside surface of the pipe to compress the spring. If the diameter exceeds the predetermined value as the system moves through the pipe, the pipe inside surface will no longer engage the fingers, which releases the spring causing the fingers to pivot to the failing position, where they remain until the system is removed from the pipe and manually reset.

A system and method for measuring an inside diameter of a pipe to determine if it exceeds a predetermined value using a plurality of fingers operatively connected to a spring. When in a fully extended position, the distance between opposite fingers is the predetermined value. The fingers are pivotable between a starting position, through the fully extended position, and to a failing position. In the starting position, an outer end of each finger engages an inside surface of the pipe to compress the spring. If the diameter exceeds the predetermined value as the system moves through the pipe, the pipe inside surface will no longer engage the fingers, which releases the spring causing the fingers to pivot to the failing position, where they remain until the system is removed from the pipe and manually reset.

Method for measuring a workpiece, comprising the method steps of: providing a workpiece, wherein the workpiece has a surface with a surface structure; predefining a geometric measured variable of the workpiece, wherein the geometric measured variable is a diameter of the workpiece and wherein the geometric measured variable and a nominal-actual deviation of the geometric measured variable are defined in a reference plane; predefining a measuring path; tactile sensing of measured values on the workpiece by bringing a measuring probe into contact with the surface of the workpiece and the measuring probe scans the workpiece in contact with the surface along the predetermined measuring path; computational determination of the geometric measured variable and the nominal-actual deviation of the geometric measured variable from the measured values within the reference plane; wherein the predefined measuring path lies at least partially outside the reference plane.

There is provided an inside-diameter measuring unit capable of automating inside-diameter measurement and a control method for automatic inside-diameter measurement. An inside-diameter measuring part is supported by a support frame part via a floating joint part. The floating joint part includes a rotation-allowing mechanism part and a translation-allowing mechanism part. A measuring head part of the inside-diameter measuring part is inserted into a hole by a robot arm part. The inside-diameter measuring part adjusts its position and posture autonomously by the reaction force when a contact point pushes against the inner wall of the hole to align the axis of the inside-diameter measuring part with the axis of the hole. An electric inside-diameter measuring unit can automatically measure the inside diameter of a hole.

There is provided an inside-diameter measuring unit capable of automating inside-diameter measurement and a control method for automatic inside-diameter measurement. An inside-diameter measuring part is supported by a support frame part via a floating joint part. The floating joint part includes a rotation-allowing mechanism part and a translation-allowing mechanism part. A measuring head part of the inside-diameter measuring part is inserted into a hole by a robot arm part. The inside-diameter measuring part adjusts its position and posture autonomously by the reaction force when a contact point pushes against the inner wall of the hole to align the axis of the inside-diameter measuring part with the axis of the hole. An electric inside-diameter measuring unit can automatically measure the inside diameter of a hole.

A method for rapidly measuring the roller pass major semi-axis of a three-roller reducing mill to improve the outer-diameter precision and surface quality of a steel pipe includes selecting a corresponding value of the average diameter of an elliptical pass, a value of a first major semi-axis, and a value of a minor semi-axis according to a rack station number of a special numerical control lathe; calculating a value of a first line segment according to an elliptic equation, the obtained value of the first major semi-axis, and the obtained value of the minor semi-axis; calculating a value of a second major semi-axis according to the right-angle triangle theorem and the value of the first line segment; and measuring a value of the first dimension by attaching three claws of a three-claw internal micrometer to three roller gaps.