Patent ID: 7621738

Claim:
A conveyor system ( 10 ) for an installation for the manufacture of thermoplastic containers by blow molding using preforms ( 12 ), of the type comprising a number of transport elements ( 18 ) which each have at least one grasping device ( 26 ) for carrying a preform ( 12 ) so as to convey it, in the vertical position, along a path in the downstream direction, inside the installation, of the type in which each grasping device ( 26 ) can move along a vertical axis (A 2 ) relative to the transport element ( 18 ) carrying it so as, when it is brought from an upper release position to a lower grasping position, to engage axially in the neck ( 14 ) of the preform ( 12 ) to be seized, characterized in that each grasping device ( 26 ) is linked in terms of upward and downward axial movement to an associated bracket ( 46 ) which is mounted so that it can slide axially in one direction (A 3 ) and which bears, at its lower axial end, a cam follower element ( 58 ), the bracket ( 46 ) being stressed axially downward so that the cam follower element ( 58 ) interacts with a surface of a fixed cam ( 66 ) provided to bring the grasping device ( 26 ) from its upper release position to its lower grasping position, in that the bracket ( 46 ) comprises a stud ( 74 ) with a bearing surface ( 76 ) designed to interact slidingly with a fixed ramp ( 78 ) comprising a control surface ( 86 ) which is inclined relative to the vertical and oriented generally upward, when the grasping device ( 26 ) is in an intermediate axial position between its upper release position and its lower grasping position, this intermediate axial position corresponding to an incorrect positioning of the grasping device ( 26 ) in the preform ( 12 ), so that the fixed ramp ( 78 ) brings the stud ( 74 ) upward and causes the grasping device ( 26 ) to slide axially into its upper release position so as to eject the associated preform ( 12 ), and in that the fixed ramp ( 78 ) extends axially at a certain height in such a way that, when the grasping device ( 26 ) is in its lower grasping position, the stud ( 74 ) can travel under the fixed ramp ( 78 ) in a passage ( 100 ) provided for this purpose.