Method for inspecting an elongated element

A method for inspecting cylinder-shaped elongated elements for smoking articles, comprising the following steps:

• selecting a working plane passing through a longitudinal axis of a first elongated element and considering a first half-space and a second half-space arranged on opposite parts with respect to the working plane;
• in an operating step of the inspection method, projecting on an external face of the first elongated element a first stripe of light from the first half-space and obtaining a first three-dimensional light trace on an inspection portion of the external face, projecting a second stripe of light from the second half-space on the inspection portion and obtaining a second three-dimensional light trace;
• processing a first view of the first elongated element, the first view being obtained by framing the first elongated element from the first half-space and identifying in the first view a respective first curved line;
• processing a second view of the first elongated element, the second view being obtained by framing the first elongated element from the second half-space, and identifying in the second view a respective second curved line;
• reconstructing a first closed curved section profile of the first elongated element by processing the first identified curved line and the second identified curved line;
• comparing the reconstructed first closed curved profile with an ideal closed section profile, to identify possible deformations of the reconstructed first closed curved profile with respect to the ideal section profile;
• wherein an ideal elongated element is arranged in a reference position alongside the first elongated element, arranged in a first position, such that the longitudinal axis of the first elongated element and a longitudinal axis of the ideal elongated element are arranged in the working plane;
• inspecting simultaneously the first elongated element and the ideal elongated element by the first stripe of light and the second stripe of light;
• obtaining from the projection of the first stripe of light a first three-dimensional light trace on an external face of the ideal elongated element and obtaining from the projection of the second stripe of light a second three-dimensional light trace on the external face of the ideal elongated element;
• framing simultaneously from the first half-space the first elongated element and the ideal elongated element so as to process the first view to identify additionally a first curved line of the ideal elongated element by a processing device;
• framing simultaneously from the second half-space the first elongated element and the ideal elongated element such as to process the second view to identify additionally a second curved line of the ideal elongated element by the processing device;
• reconstructing a closed curved section profile of the ideal elongated element by processing the first identified curved line and the second identified curved line by the processing device;
• monitoring the reconstructed closed curved profile of the ideal elongated element generating a warning by the processing device if the reconstructed closed curved profile of the ideal elongated element is different from an ideal section profile.