Belling machine for pipes made of thermoplastic material, forming end sockets equipped with an integrated seal

A belling machine (1) for pipes made of thermoplastic material, forming end sockets equipped with an integrated seal, comprising:

• means (2) for locking a pipe (3) made of thermoplastic material for keeping the pipe (3) coaxial with a belling machine (1) belling axis (b) and in the belling position;
• a forming mandrel (4) which can be forcibly inserted in a heated end (30) of the pipe (3) for forming the end into a socket, for that purpose the mandrel being able to move along the belling axis (b) and coaxial with it, between a back position in which it is disengaged from the pipe (3) and a forward position in which it is inserted in the end (30) of the pipe (3), the mandrel (4) comprising a tapered portion (40), its diameter increasing along the axis of the mandrel (4) away from the forward insertion position towards the rear disengaged position, followed, in that direction, by a cylindrical portion (41) whose diameter is equal to the maximum diameter of the tapered portion (40);
• there being the possibility of placing on the cylindrical portion (41) of the (4) mandrel, diametrically expanded, coaxially and in a predetermined position, an annular seal (5) to be integrated in the end (30) of the pipe (3) which has a socket formed on it;
• seal (5) constraining means (6), for holding the seal (5) in the predetermined position on the cylindrical portion (41) at least during insertion of the forming mandrel (4) in the end (30) of the pipe (3);
• an apparatus (7) for loading the annular seal (5) on the forming mandrel (4);
• wherein:
• the loading apparatus (7) comprises:
• a loader (8) for loading the annular seal (5) on the mandrel (4), the loader being able to move between a arming position, in which the loader (8) is spaced from the belling axis (b) and does not interfere with the mandrel (4) movement along the belling axis (b), and a loading position, in which the loader (8) is coaxial with the belling axis (b) and is located between the mandrel (4) back position, disengaged from the pipe (3), and the mandrel (4) forward position, inserted in the end (30) of the pipe (3);
• an arming device (9) which armes the loader (8) with an annular seal (5) when the loader (8) is in the arming position;
• an annular seal (5) positioner (10) in which the annular seal (5) is placed in an operating position for the action of the arming device (9);
• the loader (8) comprises:
• an annular loading flange (80), designed so that the edge (81) of its inner circular opening (82), having a diameter greater than the diameter of the cylindrical portion (41) of the mandrel (4), makes contact with a front circumferential portion (50) of the outer edge (51) of the annular seal (5);
• a plurality of gripper elements (83), each rotatably constrained to the structure of the annular loading flange (80) at a respective pivot (830) and free to rotate there about a respective axis parallel with the plane in which the annular loading flange (80) lies, between a closed position, in which one end (831) of the gripper element (83) distal from the pivot (830) presses on a rear circumferential portion (52) of the outer edge (51) of the annular seal (5), holding it against the edge (81) of the inner circular opening (82) of the annular loading flange (80), and an open position, in which said distal end (831) is spaced from the rear circumferential portion (52) of the outer edge (51) of the annular seal (5), leaving the seal (5) free to detach from the edge (81) of the inner circular opening (82) of the annular loading flange (80), the movement of the distal end (831) of each gripper element (83) from the closed position towards the open position being opposed by the action of elastic return elements (84), the gripper elements (83) being distributed along the edge (81) of the inner circular opening (82) of the annular loading flange (80) in such a way as to form a gripper device acting in a self-centring way on the annular seal (5) towards the edge (81) of the inner circular opening (82) of the annular loading flange (80);
• the shape of the distal end (831) of each gripper element (83) and the respective position, with the distal end (831) in the closed position, adopted by the pivot (830) of each gripper element (83) and the respective distal end (831), being such that a thrust applied on a lower front portion (832) of the distal end (831) towards the annular loading flange (80) along the axis of the inner circular opening (82) of the annular loading flange (80) produces a movement of the distal end (831) towards the respective open position;
• the loader (8) also comprising means (85) for mechanical interference with the surface of the mandrel (4), the means being operatively connected to the gripper elements (83);
• when the loader (8) is in the loading position, with the mandrel (4) in the back position, disengaged from the pipe (3), the inner circular opening (82) of the annular flange (80) is coaxial with the belling axis (b) and keeps a rear face (53) of the annular seal (5) facing towards the mandrel (4), the rear circumferential portion (52) of the outer edge (51) of the seal (5) belonging to said rear face;
• from the loading position, with the mandrel (4) in the back position, disengaged from the pipe (3), the loader (8) can move relative to the mandrel (4) along the belling axis (b) at least as far as a position for releasing the annular seal (5) onto the cylindrical portion (41) of the mandrel (4), coinciding with the predetermined position of the annular seal (5) on the cylindrical portion (41) of the mandrel (4), through a series of intermediate positions in which the inner circular opening (82) of the annular flange (80) is fitted on the mandrel (4) and passes along its tapered portion (40) and its cylindrical portion (41), conveying the annular seal (5) with it and causing the seal to expand diametrically along the tapered portion (40) of the mandrel (4);
• on at least an end part of the tapered portion (40) and during the passage onto the cylindrical portion (41) the loader (8) means (85) for mechanical interference with the surface of the mandrel (4) interfere with the lateral surface of the mandrel (4), which acts as a mechanical cam, and they cause the gradual movement of the distal end (831) of each gripper element (83) from the closed position towards the open position, leaving the rear face (53) of the annular seal (5) free;
• from the position where it releases the annular seal (5) on the cylindrical portion (41) of the mandrel (4), the loader (8) can move relative to the mandrel (4) along the belling axis (b) with a return movement towards the loading position, the gripper elements (83) remaining in the open position at least for an initial stretch of that return movement due to the action of the means (85) for mechanical interference, and allowing annular seal (5) release and consequent positioning in the predetermined position on the cylindrical portion (41) of the mandrel (4);
• the arming device (9) comprises a pusher (90), coaxial with a belling machine (1) arming axis (a) and able to move along the arming axis (a) between a first limit position for disengagement from the positioner (10) and a second limit position for arming the loader (8) with the annular seal (5), the annular seal (5) positioner (10) being located on the arming axis (a) between the loader (8) arming position and the first limit position for pusher (90) disengagement;
• the pusher (90) comprises:
• a cylindrical part (91), with a diameter less than the diameter of the cylindrical portion (41) of the mandrel (4) and such that it does not interfere with the means (85) for mechanical interference with the mandrel (4) when inserted in the inner circular opening (82) of the annular loading flange (80) coaxially with the latter, the cylindrical part (91) of the pusher (90) being intended to be inserted in the annular seal (5) without causing seal diametrical expansion and to support the seal (5) during the arming movement until the seal (5) is released in the loader (8);
• flat contact portions (92) lying in a plane which is perpendicular to the arming axis (a), the portions projecting outside the cylindrical part (91) of the pusher (90) and intended to make contact with the rear face (53) of the annular seal (5);
• the positioner (10) comprises a depositing cradle (100) for an annular seal (5) which is limited:
• at the bottom by a semi-circular supporting surface (101) whose concavity is facing towards the arming axis (a) and intended to support the annular seal (5) with a circumferential part (50, 52) of a portion of the outer edge (51) of the seal (5) resting on it;
• at the front, towards the pusher (90) first limit position, by a flat supporting surface (102) which is perpendicular to the arming axis (a), comprising an opening (103) for the passage of the pusher (90), the rear face (53) of the annular seal (5) and/or the rear circumferential portion (52) of the outer edge (51) of the annular seal (5) being intended to rest on an edge (104) of the opening;
• at the back, towards the loader (8) arming position, by annular seal (5) supporting elements (105) on which a front face (54) of the annular seal (5) and/or the front circumferential portion (50) of the outer edge (51) of the annular seal (5) is intended to rest;
• the positioner (10) supporting elements (105) being able to move between a first configuration, close to the arming axis (a), for supporting and guiding the front face (54) of the annular seal (5) and/or the front circumferential portion (50) of the outer edge (51) of the annular seal (5), and a second configuration, spaced from the arming axis (a) and in which the pusher (90) and the annular seal (5), loaded on the cylindrical part (91) of the pusher (90) and making contact with the respective flat contact portions (92), are free to pass through the positioner (10) and to reach the loader (8) located in the arming position, the passage from the first to the second configuration of at least part of the supporting elements (105) being caused by the thrust from the seal (5) due to the contact between the seal (5) and the flat contact portions (92);
• when the loader (8) is in the arming position, the inner circular opening (82) of the annular flange (80) is coaxial with the belling machine (1) arming axis (a) and the distal ends (831) of the gripper elements (83) remain facing towards the positioner (10), the distal ends (831) being in the closed position when there is no annular seal (5) in the loader (8);
• in the movement from the first to the second limit position, the pusher (90) passes through a series of intermediate positions one after another, in which:
• the pusher (90) reaches the opening (103) in the cradle (100) flat supporting surface (102), penetrates it and, with the contact offered by at least part of the positioner (10) supporting elements (105) which have not yet been moved to the second configuration, the pusher is inserted in the annular seal (5) positioned in the cradle (100) and carries the seal on its cylindrical part (91), sliding inside the seal until the rear face (53) of the annular seal (5) makes contact with the pusher (90) flat contact portions (92);
• when the rear face (53) of the annular seal (5) makes contact with the flat contact portions (92) of the pusher (90), the thrust that the annular seal (5) consequently applies causes said at least part of the positioner (10) supporting elements (105) to pass from the first to the second configuration and the possibility for the pusher (90), with the annular seal (5) loaded on the cylindrical part (91), to pass through the positioner (10) and reach the loader (8) in the arming position;
• the front circumferential portion (50) of the outer edge (51) of the annular seal (5) making contact with the lower front portion (832) of the distal end (831) of the gripper elements (83) and applying on it, due to the action of the pusher (90) flat contact portions (92), a thrust towards the annular loading flange (80) along the axis of the circular opening (82) which produces the movement of the distal end (831) towards the respective open position;
• the further movement of the pusher (90) causing the annular seal (5) to pass beyond the distal end (831) and, due to the action of the elastic return means (84), reclosing of the distal end (831) on the rear circumferential portion (52) of the outer edge (51) of the annular seal (5) and consequent contact between the latter and the edge (81) of the inner circular opening (82) of the annular loading flange (80), the pusher (90) having thus reached the second limit position for arming the loader (8) with the annular seal (5);
• from the second limit position for arming the loader (8) with the annular seal (5), the pusher (90) being able to move relative to the loader (8) along the arming axis (a) with a return movement towards the first limit position for disengagement from the positioner (10), the annular seal (5) remaining retained by the gripper elements (83) in the loader (8) and leaving the pusher (90) free.