Abstract: The machine for the formation of tubes includes at least, in series with each other, forming stations including pairs of idle rollers which make rototranslational movements of the same amplitude but in opposite directions, and at least one finishing station including four idle rollers having a concave profile with a constant curvature and able to perform rototranslational movements of the same amplitude and direction according to 90° axes. The lower rollers of each forming station have an elliptical profile with a curvature decreasing form the outer edge to the inner edge of the roller. The upper rollers of the first forming station have an elliptical profile with a curvature increasing from the outer edge to the inner edge of the roller; the upper rollers of the forming stations subsequent to the first have a circular profile.

Abstract: A finishing station of variable structure includes two plates, joined integrally to each other and able to slide along two vertical shoulders which support a plurality of forming rollers mounted on shoes able to slide in radial guides formed in the plates. The shoes that support the forming rollers are moved by levers hinged to the plates and connected to each other by connecting rods, two of which are hinged to levers hinged to the plates and secured to the ground. A further forming roller, situated in the lower part of the plates, is preferably secured to the ground. In the inner part of the two forming rollers situated in the upper part of the finishing station a disc blade is formed to control the position of the edges of the bent strip of sheet metal during the finishing operation.

Abstract: The machine for the formation of tubes includes at least, in series with each other, forming stations including pairs of idle rollers which make rototranslational movements of the same amplitude but in opposite directions, and at least one finishing station including four idle rollers having a concave profile with a constant curvature and able to perform rototranslational movements of the same amplitude and direction according to 90° axes. The lower rollers of each forming station have an elliptical profile with a curvature decreasing form the outer edge to the inner edge of the roller. The upper rollers of the first forming station have an elliptical profile with a curvature increasing from the outer edge to the inner edge of the roller; the upper rollers of the forming stations subsequent to the first have a circular profile.

Abstract: A finishing station of variable structure includes two plates, joined integrally to each other and able to slide along two vertical shoulders which support a plurality of forming rollers mounted on shoes able to slide in radial guides formed in the plates. The shoes that support the forming rollers are moved by levers hinged to the plates and connected to each other by connecting rods, two of which are hinged to levers hinged to the plates and secured to the ground. A further forming roller, situated in the lower part of the plates, is preferably secured to the ground. In the inner part of the two forming rollers situated in the upper part of the finishing station a disc blade is formed to control the position of the edges of the bent strip of sheet metal during the finishing operation.