Method and apparatus for shaping a normally rigid plastic pipe

Apparatus for shaping a normally rigid plastic tube having a softened end zone, the apparatus comprising

• a. a mandrel comprising a hollow cylinder made of a resiliently deformable rubber and dimensioned for insertion inside the softened end zone and adjacent rigid portions of a plastic tube to be shaped,
• b. a piston rod having inner and outer ends and mounting the mandrel adjacent said inner end,
• c. die means freely surrounding the mandrel and arranged to surround the softened end zone and an adjacent rigid portion of a tube to be shaped,
• d. a first abutment rigidly mounted on the inner end of a piston rod and arranged for bearing engagement with the adjacent end of the mandrel,
• e. a second abutment freely slidable on the piston rod and extending into the die means for bearing engagement with both the adjacent end of the mandrel and the face of the softened end of a tube to be shaped,
• f. a fluid pressure cylinder integral with and extending outwardly from the second abutment and freely encircling the piston rod intermediate the ends of the latter, and
• g. a piston fixed to the piston rod within the cylinder, whereby the application of fluid pressure to one end of the cylinder effects movement of the cylinder along the piston rod and extension of the second abutment into the die means, thereby compressing the mandrel between the first and second abutments and expanding the mandrel radially while simultaneously shortening it axially, contemporaneously securing the plastic tube and mandrel within the die means against axial displacement and expanding the softened end zone of the plastic tube radially outward into forming contact with the die means, and the application of fluid pressure to the opposite end of the cylinder effects retraction of the cylinder and second abutment outwardly relative to the die means to return the mandrel to its original relaxed condition.