| 摘要 |
The invention relates to a pressurized-fluid workhead for permanent bell-forming of tracts of ends of plastic pipes, comprising: a die exhibiting a cavity for receiving a thermally plasticized end tract of a pipe, being provided with flow conduits for a pressurized fluid; a forming buffer, insertable into the end tract of the pipe and arranged centrally to the die and further exhibiting flow pipes for a pressurized fluid; a flange mounted coaxially and slidably with respect to the buffer and die, and having a striking surface which is associable to an edge of the end tract of the pipe; sealing elements located on the die and the buffer, destined to interact with an external surface and an internal surface of the end tract of the pipe. The die, the buffer and the flange together peripherally define a forming chamber of the end tract of the pipe, said forming chamber being subdivided by the pipe into a first and a second pressure chamber of a fluid; the first pressure chamber being arranged between the lateral surface of the buffer and the internal surface of the pipe; the second chamber being arranged between the external surface of the pipe and the internal surface of the die; the pressure chambers being fed by the conduits such as circumferentially and successively to dilate and contract the end tract of the pipe, to produce a ribbing of the pipe.
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