Device for gripping containers

1. A device for gripping containers, comprising clamps ( 8 ) adapted to clamp a container ( 20 ), and a centring cone ( 5 ) adapted to receive a cap ( 23 ) of the container ( 20 ), said centring cone ( 5 ) having a longitudinal axis (A) and comprising an inlet mouth ( 10 ), for entrance of said cap ( 23 ), and an inner lateral surface ( 11 ), said inner lateral surface ( 11 ) comprising a first, substantially cylindrical portion ( 12 ) and a second portion ( 13 ) comprised between the first portion ( 12 ) and the inlet mouth ( 10 ) and diverging outwards in the direction from the first portion ( 12 ) to the inlet mouth ( 10 ), wherein the centring cone ( 5 ) is a component separate from and independent of the clamps ( 8 ), and wherein the centring cone ( 5 ) is rotatably mounted in the device for gripping containers.

2. The device according to claim 1 , wherein the first portion ( 12 ) of the inner lateral surface ( 11 ) of the centring cone ( 5 ) has a knurled region ( 14 ) so as to be able to match with a knurled region ( 26 ) of the cap ( 23 ) of the container ( 20 ).

3. The device according to claim 1 , wherein the centring cone ( 5 ) can be integrally connected to a measuring unit for measuring a torque for removing the cap ( 23 ) from the container ( 20 ).

4. The device according to claim 1 , wherein the centring cone ( 5 ) is made of a substantially rigid material so that it is not deformed or is deformed only to a negligible extent, when the cap ( 23 ) of the container ( 20 ) is fitted thereinto.

5. A plant for conveying containers ( 20 a , 20 b ), comprising a conveyor belt ( 101 ) on which the containers ( 20 a , 20 b ) are advanced, and a transferring apparatus ( 103 ) comprising a supporting arm ( 104 ) at the end of which a head ( 105 ) having at least one gripping device ( 106 , 107 ) according to claim 1 .

6. A method of gripping a container ( 20 ) having a cap ( 23 ) located on a conveyor for removal therefrom by means of a gripping device ( 1 ) comprising clamps ( 8 ) and a centring cone ( 5 ) having a longitudinal axis (A), said centring cone ( 5 ) comprising an inlet mouth ( 10 ) and an inner lateral surface ( 11 ); wherein the inner lateral surface ( 11 ) comprises a first, substantially cylindrical portion ( 12 ) and a second portion ( 13 ) comprised between the first portion ( 12 ) and the inlet mouth ( 10 ) and diverging outwards in the direction from the first portion ( 12 ) to the inlet mouth ( 10 ), said method comprising the steps of:

bringing the gripping device ( 1 ) to a position above a container ( 20 ) to be gripped,

lowering the gripping device ( 1 ) with its clamps ( 8 ) open, onto the container ( 20 ),

inserting the cap ( 23 ) of the container ( 20 ) into the centring cone ( 5 ) through the inlet mouth ( 10 ) of the centring cone ( 5 ), and guiding the cap ( 23 ) towards the center of the centring cone ( 5 ) by means of the second portion ( 13 ) of the inner lateral surface ( 11 ) of the centring cone ( 5 ) if the cap ( 23 ) of the container ( 20 ) is offset relative to the centring cone ( 5 ),

fitting the cap ( 23 ) into the first portion ( 12 ) of the centring cone ( 5 ), and aligning the cap ( 23 ), and therefore the container ( 20 ), by rotating the axis (B) of the container ( 20 ) until said axis (B) is brought to coincide with the longitudinal axis (A) of the centring cone ( 5 ) if the axis (B) of the container ( 20 ) is inclined relative to the longitudinal axis (A) of the centring cone ( 5 ),

bringing the clamps ( 8 ) into engagement with the container ( 20 ).

7. The method according to claim 6 , wherein the first portion ( 12 ) of the inner lateral surface ( 11 ) of the centring cone ( 5 ) has a knurled region ( 14 ), said method comprising the additional step of:

matching the knurled region ( 14 ) of the first portion ( 12 ) with a knurled region ( 26 ) of the cap ( 23 ) by compensating for any misalignment between said knurled region ( 14 ) of the first portion ( 12 ) and said knurled region ( 26 ) of the cap ( 23 ), by means of the rotation of the container ( 20 ) and/or of the centring cone ( 5 ) about their respective axes (A, B).

8. The method according to claim 6 , wherein the gripping device ( 1 ), during the aforesaid steps, is advanced at a speed (v) equal to a speed of a conveyor belt ( 30 ) on which the container ( 20 ) stands.

9. A method of releasing a container ( 20 ) having a cap ( 23 ) from a gripping device ( 1 ) onto a surface, the gripping device ( 1 ) comprising clamps ( 8 ) and a centring cone ( 5 ) having a longitudinal axis (A), said centring cone ( 5 ) comprising an inner lateral surface ( 11 ) comprising a substantially cylindrical portion ( 12 ), said method comprising the steps of:

bringing the gripping device ( 1 ), with its clamps ( 8 ) closed, clamped on a container ( 20 ), to a position in which the container ( 20 ) is to be released;

causing opening of the clamps ( 8 ) and simultaneously vertically raising the gripping device ( 1 );

causing sliding, by means of the movement of the gripping device ( 1 ) upwards, an outer lateral surface ( 24 ) of the cap ( 23 ), on the substantially cylindrical portion ( 12 ) of the inner lateral surface ( 11 ) of the centring cone ( 5 ), and aligning the cap ( 23 ), and therefore the container ( 20 ), if the axis (B) of the container ( 20 ) is inclined relative to the longitudinal axis (A) of the centring cone ( 5 ), by rotating the axis (B) of the container ( 20 ) until said axis (B) is brought to coincide with the longitudinal axis (A) of the centring cone ( 5 );

taking the cap ( 23 ) of the container ( 20 ) out of the centring cone ( 5 ) with the axis (B) of the container ( 20 ) aligned relative to the longitudinal axis (A) of the centring cone ( 5 ).

10. The method according to claim 9 , wherein the gripping device ( 1 ), during the aforesaid steps, is advanced at a speed (v) equal to a speed of a conveyor belt ( 30 ) on which the container ( 20 ) stands.