Apparatus for the precision measurement of internal tube diameter over a long distance

摘要

Device intended to be introduced and moved axially in a cylindrical casing (100), of axis D1 and internal diameter (110), in order to measure the said internal diameter (110). According to the invention, the device includes a measurement apparatus (400), and, placed in alignment, a reading head (200) comprising contact elements (310, 320, 330) of spherical shape which can move radially with respect to the said axis D1 and consist of a magnetic material, a transmitter (210) capable of moving along the said axis D1 with respect to the said measurement apparatus under the action of an elastic means (500), the said transmitter having a body of substantially conical shape which bears on the said contact elements to hold them in contact with the internal wall (101) of the said casing (100), and a rigid holding means (260) with axial polarisation positioned opposite the said transmitter, facing the said contact elements, and having a polarised planar bearing surface (260a) perpendicular to the said axis D1, used as a bearing surface for the said contact elements. IMAGE