APPARECCHIATURA PER LA CURVATURA DI TUBI METALLICI

The object of the invention is an apparatus for bending metal pipes, particularly pipes having a means and a great diameter. The apparatus is associated with a vertical press (1,2) and comprises two lower pipe-bearing cradle members (4) with their upper surface (104) being semi-circular in cross-section, and an upper pipe-bending saddle member (6) arranged between the two cradle members (4), with its lower surface (106) corresponding to an intrados part of a tore. At least the pipe-bending saddle member (6) and preferably also the pipe-bending cradle members (4) have each in the central region of their surface in contact with the pipe (T), two opposite lateral depressions (306,304) which are provided in symmetrical positions with respect to the longitudinal median vertical plane of the saddle member (6) or of the cradle member (4) in areas at 45 DEG of the said saddle member (6) or cradle member (4). The said depressions (306,304) are so sized that a slight pressure applied by means of the pipe-bending saddle member (6) on the pipe (T) to be bent on starting the bending thereof, causes an expanding of said pipe into the lateral depressions (306,304), so that conforming protuberances (T1,T2) are formed in said pipe, and a contact surface between pipe (T) and the pipe-bending saddle member (6) and between pipe (T) and the pipe-bearing member (4) is thus obtained, the said surface being of such a width that on subsequent by increasing the pressure as applied by means of the pipe-bending saddle member (6) up to obtain the moment of flexure which is required for bending the pipe (T), any specific pressure is prevented from being reached, which would be apt to produce the narrowing of said pipe.