| 摘要 |
A forming apparatus (1) for making a bell joint (60) on an end (51) of a plastic material pipe (50) by hot plastic deformation includes moulding means (9) for externally enclosing the end (51) and a mandrel (2) movable along a longitudinal direction (A) and insertable into the end (51) in order to form the bell joint (60) in cooperation with the moulding means (9), the mandrel (2) being provided with a plurality of sectors (3) that can be transversally and externally expanded towards the moulding means (9) in an extended position (E) in order to form on a side wall (61) of the bell joint (60) an annular seat (62) for a sealing gasket; the apparatus (1) further includes a first compressing flange (12), movable along the longitudinal direction (A) and cooperating with the moulding means (9) for abutting against and forming the side wall (61) at the annular seat (62), and a second compressing flange (14) movable along the longitudinal direction (A), interposed between the first compressing flange (12) and the mandrel (2) and arranged to abut against and compress an end front portion (63) of the bell joint (60) so as to upset the plastic material against the moulding means (9), the first compressing flange (12) and the sectors (3) arranged in the extended position (E) in order to precisely form the seat (62) and the end front portion (63) of the bell joint (60). |
