| 摘要 |
<p>An enhanced pressurisable fluid operating head for providing permanent bell-mouth shape to terminal portions, provided with gasket seats, of pipes made of plastic material and in particular polyethylene (PE) and polypropylene (PP), comprising: a shaped forming drift (55), comprising a second portion (552) with greater nominal diameter than the pipe and at least two half-moulds (52) surrounding the drift (55) and comprising a shaped surface (53) and a radial cavity (56), the half-moulds (52), the drift (55) and a flange (60) acting as a frontal stop of the edge (62) of the terminal portion (50) of the pipe (51), fitted on the drift (55), delimiting a first pressurisation chamber which allows a first phase of dilation of the terminal portion (50) of the pipe against the half-moulds (52), and a second chamber (64) which allows a second contraction phase of the same portion (50), onto the underlying drift (55), said drift (55) being of the type comprising a seat (551) for the sealing gasket (11), therein preliminarily placed in temporary fashion, whereas the flange (60), suitably heated in a concentrated manner, has its own extremity (600) shaped at least with a double step (602,603) in which the outer step (602), in combination with the shaped inner surface (53) of the half-moulds (52) in closed position on the drift (55) and with the underlying inner step (603), placed downstream of and against the gasket (11), identifies a cylindrical seat (700) for the edge (62) of the terminal portion (50) of the pipe (51), having a pre-set minimum diameter that is greater than the diameter of the second portion (552). <IMAGE></p> |
