MEASUREMENT DEVICE AND MEASUREMENT METHOD OF SCREW SHAFT

To measure the effective diameter of a screw shaft.SOLUTION: A measurement device comprises: an imaging control unit which images an upper contour of a screw shaft of a ball screw and a lower contour on the opposite side to the upper contour; an outer diameter detection unit which detects the outer diameter position of the screw shaft in the photographed image; an axial line specification unit which specifies the axial line position of the screw shaft on the basis of the outer diameter position of the screw shaft in the photographed image targeting the upper contour and the outer diameter position of the screw shaft in the photographed image targeting the lower contour; and a difference calculation unit which calculates a difference value between a first axial line position specified when a rotation angle of the screw shaft is set to a first rotation angle and a second axial line position specified when the rotation angle of the screw shaft is set to a second rotation angle different from the first rotation angle.SELECTED DRAWING: Figure 6 【課題】ねじ軸の有効径を測定する。【解決手段】測定装置は、ボールねじのねじ軸の上輪郭と、上輪郭の反対側の下輪郭を撮像する撮像制御部と、撮像画像においてねじ軸の外径位置を検出する外径検出部と、上輪郭を対象とする撮像画像におけるねじ軸の外径位置と、下輪郭を対象とする撮像画像におけるねじ軸の外径位置に基づいて、ねじ軸の軸線位置を特定する軸線特定部と、ねじ軸の回転角が第１の回転角に設定されるときに特定される第１の軸線位置と、ねじ軸の回転角が第１の回転角とは異なる第２の回転角に設定されるときに特定される第２の軸線位置との差分値を算出する差分算出部と、を備える。【選択図】図６