Machine for manufacturing corrugated structures

A machine for manufacturing, out of a thin strip of filtering material, a flat and flexible folded structure that presents on each one of its two sides a series of parallel folded ribs showing ridges in a zigzagging pattern and corresponding to a series of cavities on the other side, and where each ridge of a rib is connected to each zigzagging line at the bottom of a contiguous cavity by a folded side consisting of a succession of facets in the shape of parallelograms, said machine including:

• two marking rollers with parallel axes, placed on either side of the direction of movement of the strip, respectively, and driven synchronously for the purpose of marking on the two sides of the strip impressions indicating the ridges of the ribs and the folds in the folded structure, where each roller presents a first and a second set of projecting marking lines corresponding, the first set, to the ridges of the ribs or to the bottom of the cavities, and the second set, to the folds in the sides of such ribs or cavities, respectively;
• means forming a guide passage limited laterally by two walls converging toward its exit;
• means to push the structure that is undergoing folding into the passage at a constant speed, characterized by the fact that the marking is such that the folded ribs run along the length of the strip and that the passage is fixed and enclosed vertically by two smooth walls, gradually diverging toward its exit in such manner that the transversal section of the entrance of the passage is practically complementary to the flattened rectangular section of the strip marked and not folded and that each section of the said passage by a vertical plane closely envelops the section of the structure that is being folded cut along the same plane, and the two diverging walls also present longitudinal smooth guiding ribs, the height of which increases toward the exit and which run along the median lines of the cavities enclosed between the folded ribs to be formed.