Apparatus, system, and method for measuring thread features on pipe or tube end

A method of measuring thread features of a threaded pipe or tube end, comprising the steps of:

• measuring a first thread feature, which does not relate to measurement of a thread flank surface, with an optical sensor by detecting light that reaches from a light source located on the opposite side of the pipe or tube axis and runs substantially in parallel to the thread grooves;
• measuring a second thread feature, which relates to measurement of the thread flank surface, with a contact sensor by contacting a contact probe onto a thread flank surface and detecting the space coordinates of the contact probe at a time of contact;
• and
• calculating thread features from the combination of the first thread feature and the second thread feature,
• wherein in the step of measuring the second thread feature, a profile of the thread flank surface is measured with the contact sensor by contacting the contact probe onto measuring points of the thread flank surface, the measuring points being spaced each other at different distances to the pipe or tube axis,
• wherein in the step of calculating thread features, a profile of an area other than the thread flank surface measured by the optical sensor and the profile of the thread flank surface measured by the contact sensor are combined with each other to calculate a thread profile, and
• wherein the thread flank surface includes a hooked frank surface having a hook shape.