| 摘要 |
PURPOSE:To measure exactly the inside diameter of a steel pipe by measuring the outside diameters at plural points of the steel pipe moving in a horizontal direction by means of outside diameter measuring instruments and subtracting the measured values of the wall thickness on both sides corresponding to the measured outside diameters from the measured values of the outside diameters. CONSTITUTION:Plural pieces of the optical outside diameter measuring instruments 1 are provided at prescribed intervals to the steel pipe 3 moved continuously in the horizontal direction by conveying rollers 2 in the same direction. Each of the plural instruments 1 measures automatically the outside diameter D of the steel pipe 3 moved to the prescribed position. The inside diameter d1 of the steel pipe 3 is calculated by an inside diameter calculator 5 according to d1=D1-(t1+t2) from the measured value of the outside diameter obtd. in the above-mentioned manner, for example, D1 and the measured values t1, t5 of the wall thickness on both sides corresponding thereto. The measuring thickness of the resultant inside diameter of the pipe 3 is 0.07mm mean square of the measuring accuracy of the device 1 and a wall thickness measuring instrument 4 if said accuracy is assumed to be both + or -0.05mm. The measuring accuracy is thus made considerably higher than heretofore. |
