Device for sealing bags containing powder or granular materials

1. A device for closing valved bags, having a projecting valve, for containing powder or granular materials, suitable for installation within a belt, roller or similar line for conveying bags, comprising:

at least one sealing head; and

a conveyor means for feeding the bags to the sealing head,

wherein the sealing head presents drive means causing the sealing head to advance, during the sealing process, at the same speed and direction as the conveyor means and to simultaneously move the sealing head in a direction perpendicular to the direction of the conveyor means to enable the sealing head to seal the projecting valve of the bag while the conveyor means is moving,

wherein the drive means comprise a guide on which the sealing head is slidable, and

wherein the guide is inclined to a resting surface of the conveyor belt.

2. The device as claimed in claim 1 , wherein the conveyor means is a conveyor belt or a roller conveyor.

3. The device as claimed in claim 1 , wherein the sealing head is of toothed wheel type.

4. The device as claimed in claim 1 , wherein the inclination (α) of the guide to the surface of the conveyor means is 60°.

5. The device as claimed in claim 1 , wherein the horizontal component of the speed of the sealing head is equal to the speed of the conveyor means.

6. The device as claimed in claim 1 , wherein a retaining roller is provided upstream of the sealing head.

7. The device as claimed in claim 1 , wherein a pacing roller is provided upstream of the conveyor means.

8. A device as claimed in claim 1 , further comprising upstream of the sealing head a conveyor belt inclined to a retaining wall, said belt urging the bags towards the retaining wall.

9. The device as claimed in claim 1 , wherein upstream of the sealing head a roller conveyor is present comprising a plurality of rollers presenting their axes of rotation parallel to each other and inclined to a retaining wall, said rollers, by their movement, urging the bags towards the retaining wall.

10. The device as claimed in claim 9 , wherein the retaining wall presents for the bags a movable bearing surface comprising a sliding band passing taut between two rollers, one of which is motorized.

11. The device as claimed in claim 9 , wherein said retaining wall presents means for adjusting its position relative to the roller conveyor.

12. A device for closing valved bags, having a projecting valve, for containing powder or granular materials, suitable for installation within a belt, roller or similar line for conveying bags, comprising at least one sealing head and a conveyor means for feeding the bags to the sealing head, wherein the sealing head presents drive means causing the sealing head to advance during the sealing process, at the same speed as the conveyor means to enable the sealing head to seal the projecting valve of the bag while the conveyor means is moving,

wherein the drive means comprise a guide on which the sealing head is slideable, and

wherein the sealing head is connected to a connecting rod-crank linkage operated by a brushless motor associated with an electronic control device.

13. A device for closing valved bags, having a projecting valve, for containing powder or granular materials, suitable for installation within a belt, roller or similar line for conveying bags, comprising at least one sealing head and a conveyor means for feeding the bags to the sealing head, characterised in that the sealing head presents drive means causing it to advance, during the sealing process, at the same speed as the conveyor means to enable it to seal the projecting valve of the bag while the conveyor means is moving,

wherein a valve cleaning unit is provided upstream of the sealing head to clean the valve of dust traces.

14. The device as claimed in claim 13 , wherein the valve cleaning unit comprises at least one nozzle presenting its own drive means enabling it to advance at the same speed as the conveyor means, so that it is able to clean the valve while the conveyor means is moving.

15. The device as claimed in claim 13 , wherein the valve cleaning unit comprises a series of nozzles connected to compressed air and fed sequentially.

16. The device as claimed in claim 13 , wherein the valve cleaning unit comprises a structure which directly supports at least one nozzle, said structure presenting means conferring a swinging movement on said structure.