Plant for blow-moulding plastic containers, particularly bottles

1. A blow-moulding plant for making plastic containers ( 2 ) from respective parisons ( 3 ), comprising:

a blow-moulding line ( 7 ) equipped with a plurality of moulding units ( 15 ), each comprising at least two cavities ( 19 ) for blow-moulding respective containers ( 2 ), the moulding cavities ( 19 ) of each moulding unit ( 15 ) having respective first longitudinal axes ( 19 a ) positioned at a first predetermined distance (D 2 ) from each other;

a flexible feed conveyor ( 41 ) which is equipped with a plurality of members ( 43 ) for picking up and transporting respective parisons ( 3 ) and which extends through a thermal conditioning device ( 38 );

a parison ( 3 ) transfer device ( 39 ) coupled to the blow-moulding line ( 7 ) at a first transfer station ( 13 ) for transferring the parisons ( 3 ) to the moulding units ( 15 ) and coupled to the flexible feed conveyor ( 41 ) at a second transfer station ( 40 ) for receiving the parisons ( 3 );

a plurality of pick-up and transfer members ( 43 ) associated with the flexible feed conveyor ( 41 ) for moving the parisons ( 3 ) individually along a predetermined path,

wherein the flexible feed conveyor ( 41 ) extending through the thermal conditioning device ( 38 ), at the second transfer station ( 40 ), is shaped in such a way that couples of consecutive parisons ( 3 ) engaged with the respective pick-up and transfer members ( 43 ) of the flexible feed conveyor ( 41 ) are spaced on the flexible feed conveyor ( 41 ) according to a spacing (P 1 ) that is equal to the first distance (D 2 ) so that they can be picked up directly from the transfer device ( 39 ) and put in the cavities ( 19 ) of the corresponding moulding unit ( 15 ),

wherein the flexible feed conveyor ( 41 ) comprises a chain arranged in closed loop and having a succession of rotating joints, each joint defines a vertical rotation axis, each pick-up and transfer members ( 43 ) has (i) a structure connected at two consecutive rotating joints of the chain whereby it is hooked up to the conveyor ( 41 ) to project outwardly from the chain loop in cantilever fashion, and (ii) a mandrel ( 47 ) pivotally coupled to the structure to rotate about a vertical axis,

wherein the mandrel of each pick-up and transfer members ( 43 ) has a pinion at its top end, which is configured to engage with a stationary element to put the mandrel in rotation as a consequence of the movement of the corresponding pick-up and transfer member ( 43 ) along said predetermined path.

2. The plant according to claim 1 , wherein the flexible feed conveyor ( 41 ) has at least one curved stretch (T) at the second transfer station ( 40 ).

3. The plant according to claim 2 , wherein the flexible feed conveyor ( 41 ) comprises at least one straight stretch; the pick-up and transport members ( 43 ) and the parisons ( 3 ) associated with them being spaced along said straight stretch according to another spacing that is different from the spacing (P 1 ).

4. The plant according to claim 1 , wherein the transfer device ( 39 ) comprises a single transfer wheel ( 39 ) connected to the blow-moulding line ( 7 ) and to the flexible feed conveyor ( 41 ) at the first and second transfer stations ( 13 , 40 ), respectively.

5. The plant according to claim 1 , wherein the transfer device ( 39 ) comprises at least one pick-up and transporting unit ( 65 ) mobile through the first and second transfer stations ( 13 , 40 ) to feed into a moulding unit ( 15 ) a number of parisons ( 3 ) equal to the number of moulding cavities ( 19 ).

6. The plant according to claim 5 , wherein the pick-up and transporting unit ( 65 ) comprises a plurality of pick-up and transporting elements ( 75 ) equal in number to the number of moulding cavities ( 19 ) of one moulding unit ( 15 ).

7. The plant according to claim 6 , wherein the pick-up and transporting elements ( 75 ) of each pick-up and transporting unit ( 65 ) have respective second longitudinal vertical axes ( 75 a ) positioned at a predetermined second distance (D 1 ) from each other; the second distance (D 1 ) being fixed and equal to the first distance (D 2 ).

8. The plant according to claim 1 , wherein the flexible feed conveyor ( 41 ) and the blow-moulding line ( 7 ) are movable along a first and a second annular path (S, P), respectively, an orienting device ( 56 , 62 , 66 ) being provided for keeping the pick-up and transporting units ( 65 ) of the blow-moulding line ( 7 ) substantially parallel with the first path (S) at the second transfer station ( 40 ) and with the second path (P) at the first transfer station ( 13 ) so that the parisons ( 3 ) at the second transfer station ( 40 ) are held simultaneously both by the pick-up and transporting units ( 65 ) and by the pick-up and transport members ( 43 ).

9. The plant according to claim 1 , wherein each moulding unit ( 15 ) moves along a second annular path (P), comprises two half-moulds ( 17 a , 17 b ) mobile relative to each other between a position for opening and a position for closing the respective moulding cavities ( 19 ) and has a plane ( 20 ) where the two half-moulds ( 17 a , 17 b ) close and which is substantially parallel to the path (P).

10. The plant according to claim 1 , wherein the flexible feed conveyor ( 41 ) is a chain conveyor.

11. A blow-moulding plant for making plastic containers ( 2 ) from respective parisons ( 3 ), comprising:

a blow-moulding line ( 7 ) equipped with a plurality of moulding units ( 15 ), each comprising at least two cavities ( 19 ) for blow-moulding respective containers ( 2 ), the moulding cavities ( 19 ) of each moulding unit ( 15 ) having respective first longitudinal axes ( 19 a ) positioned at a first predetermined distance (D 2 ) from each other;

a flexible feed conveyor ( 41 ) which is equipped with a plurality of members ( 43 ) for picking up and transporting respective parisons ( 3 ) and which extends through a thermal conditioning device ( 38 );

a parison ( 3 ) transfer device ( 39 ) coupled to the blow-moulding line ( 7 ) at a first transfer station ( 13 ) for transferring the parisons ( 3 ) to the molding units ( 15 ) and coupled to the flexible feed conveyor ( 41 ) at a second transfer station ( 40 ) for receiving the parisons ( 3 );

a plurality of pick-up and transfer members ( 43 ) associated with the flexible feed conveyor ( 41 ) for moving the parisons ( 3 ) individually along a predetermined path,

wherein the flexible feed conveyor ( 41 ) extending through the thermal conditioning device ( 38 ), at the second transfer station ( 40 ), is shaped in such a way that couples of consecutive parisons ( 3 ) engaged with the respective pick-up and transfer members ( 43 ) of the flexible feed conveyor ( 41 ) are spaced on the flexible feed conveyor ( 41 ) according to a spacing (P 1 ) that is equal to the first distance (D 2 ) so that they can be picked up directly from the transfer device ( 39 ) and put in the cavities ( 19 ) of the corresponding molding unit ( 15 ),

wherein the flexible feed conveyor ( 41 ) comprises a chain arranged in closed loop and having a succession of rotating joints, each joint defines a vertical rotation axis, each pick-up and transfer members ( 43 ) has (i) a holding structure connected at two consecutive rotating joints of the chain whereby it is hooked up to the conveyor ( 41 ) to project outwardly from the chain loop in cantilever fashion, and (ii) a mandrel ( 47 ) pivotally coupled to the structure to rotate about a vertical axis,

wherein the chain comprises at least a central portion defined by a plurality of chain links mashed with the rotating joints, an upper portion defined by a first plurality of pins extending from respective rotating joints and projecting upward from said central portion, and a lower portion defined by a second plurality of pins extending from respective rotating joints and projecting downward from said central portion,

wherein the holding structure of each pick-up and transfer members ( 43 ) has an upper arm connected to two consecutive pins of said first plurality of pins and a lower arm connected to corresponding two consecutive pins of said second plurality of pins.

12. The blow-moulding plant of claim 11 , wherein, in the holding structure of each pick-up and transfer members ( 43 ), the upper arm and the lower arm are detachable from a remaining body of the holding structure itself through locking elements provided between the upper arm and the body of the holding structure and between the lower arm and the body of the holding structure.