EP0490607A1

EP0490607A1 - Improvements in or relating to filling heads

Info

Publication number: EP0490607A1
Application number: EP91311416A
Authority: EP
Inventors: James Ian Davidson
Original assignee: BAGFILLA Ltd
Current assignee: BAGFILLA Ltd
Priority date: 1990-12-11
Filing date: 1991-12-09
Publication date: 1992-06-17

Abstract

A filling head suitable for insertion into the top of a bag to be filled, comprising an inner cylindrical duct (10) defining an outlet (16) through which material is deposited into a bag from a hopper (14). An outer duct (21) extends concentrically around the duct (10) to provide an annular extraction duct (21) through which air borne material may be extracted from the neck of the bag being filled. Two hinged, semi-circular doors (24) are provided across the inlet (23) of the duct (21) and the outlet (16) of the duct (10). The doors (24) are operable to simultaneously close off or open both the inlet (23) and the outlet (16) when a bag is in position on the filling head. The doors (24) are operated manually by means of a linkage mechanism comprising a lever-and-crank assembly and two tension springs (20) attached between the said assembly and each door (24) respectively.

Description

The present invention concerns improvements in or relating to filling heads, especially but not exclusively filling heads for use in apparatus for filling large bags, typically of 1 tonne capacity, with fluent materials, for example powders.
A typical filling head includes a cylindrical duct through which fluent material passes into a bag to be filled, the duct providing communication between a valve at the bottom of a material hopper and the inlet to the bag. Normally such ducts are surrounded by a further duct to define an annulus around the cylindrical duct through which dust created at the bag entry during the filling operation can be extracted.
A problem with this apparatus is that when the bag is filled it is not unusual for a small amount of material to remain both in the filling duct and also in the outer annular duct (particularly when the extraction force has been switched off) and it is often found when the bag is removed, owing to vibrations or small movements within the filling apparatus, this small amount of material is dislodged, discharging into the space normally occupied by the bag and thereby causes a dust hazard.
It is an object of the present invention to obviate or mitigate this disadvantage.
According to the present invention there is provided a filling head adapted for insertion into a container to be filled, the head comprising at its outlet closure means movable between a first position in which the outlet is open, and a second position in which the outlet is closed, and means for moving said closure means between said first and second positions when the filling head is inserted in the container.
Preferably the head comprises a first duct defining the outlet through which a material may enter the container, and a second duct defining an inlet through which material may enter the head, the closure means being so formed as to close off the said outlet and inlet when in the second position.
Preferably the closure means comprises at least one door movable between the first and second positions.
Preferably the first and second ducts are concentric with the second duct surrounding the first duct.
Preferably the closure means comprises two semi-circular doors hingedly mounted along their diameters across a diameter of both the inlet and outlet.
Preferably the means for moving the closure means comprises a manually operable linkage mechanism which includes resilient means attached to a surface of each door and to a lever-and-crank door operating assembly such that during closure of the outlet, the assembly raises the resilient means and consequently urges the doors into the second, closed position. The resilient linkage may comprise a spring or springs or a wire.
Preferably the door operating assembly has an over-centre action to retain the closure means in the second, closed position with the resilient means in tension. Preferably the door operating assembly comprises a manually operable handle attached to a shaft extending at least partially across the diameter of the head, a crank lobe rigidly fixed to said shaft within the head, and a generally C-shaped link pivotally connected at one end to the lobe and at the other end to the resilient means.
In a modification it is preferable that the or each door is still hinged but that other door operating assemblies are employed which ensure that in the closed position the or each door is held firmly against both the inlet and the outlet of the head.
Further according to the present invention there is provided a filling head adapted for insertion into a container to be filled, the head comprising a first duct defining an outlet through which a material may enter the container, a second duct defining an inlet through which material may enter the head, and closure means movable between a first position in which the inlet and outlet are open and a second position in which the inlet and outlet are closed.
Still further according to the present invention there is provided a filling head adapted for insertion into a container to be filled, the head comprising at its outlet a pair of doors movable from a first open position to a second closed position in which they close off the outlet and means for moving said doors between said open and closed positions, said means incorporating a resilient linkage.
An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which:-

Fig. 1 is a perspective view of a filling head according to the present invention, with the closure means in an open position; and
Fig. 2 is a diagrammatic side view of the filling head of Fig. 1 with the closure means in a closed position.

A filling head comprises a cylindrical duct 10 which is adapted for connection to the outlet from a control valve 12 (Fig. 2) at the base of a hopper 14 containing powder to be supplied to a large capacity bag (not shown) to be filled, that bag being fitted with its inlet in communication with an outlet 16 of the filling head. A further cylindrical member 18 having an outwardly flared lower end 20 is mounted concentrically around the duct 10 and defines therewith an annular duct 21. The duct 21 is connected at its upper end 22 to dust extraction apparatus (not shown). The lower end 20 of the cylindrical member 18 defines, with the duct 10, an annular inlet 23 to the duct 21.
In operation of this apparatus the inlet to a bag to be filled is placed around the flared end 20, to be in communication with the outlet 16 and the inlet 23. Opening of the valve 12 allows powder from the hopper 14 to fall through the duct 10 through the outlet 16, and into the bag. The filling operation is continued until the weight of the bag reaches a predetermined value at which stage the valve 12 is closed. During this operation, dust at the bag inlet is removed by the extraction apparatus drawing the dust up through the inlet 23 into and out of the annular duct 21.
This has proved in the past to be an effective dust suppression apparatus during the filling operation.
It has been discovered, however, that when the filling operation is concluded and the bag is removed there often remains a small amount of powder in the duct 10 and also the annular duct 21 particularly when the extraction apparatus has been switched off. This is often dislodged when the bag is being or has been removed, for example when the filling apparatus is accidentally knocked. This creates a dust problem.
The present invention seeks to obviate or mitigate this difficulty by providing a pair of semi-circular doors 24 operable to simultaneously close off both the outlet 16 and the inlet 23 when the bag is in position on the flared end 20 of the apparatus. The doors 24 are hinged along their diameters 26 about a hinge axis 28 extending diametrically across the outlet 16 and the inlet 23. It will be realised that in the fully opened position (Fig. 1) the doors 24 hang vertically downwards from the head and therefore present a minimal obstruction to the flow of material into the bag during the filling operation. When the bag is removed or just before the bag is removed, the doors 24 can be closed manually by a link assembly provided in the head, the assembly causing the doors 24 to swing upwards about the hinge 28 so that they close off both the outlet 16 and the inlet 23 to the annular passage 21 (Fig. 2).
The link assembly may take any convenient form but in the drawings comprises a pair of tension springs 30 attached by one of their ends to lugs 32 on the inner face of each door 24. The other end of both springs 30 is connected to one end of a "C" shaped link 34 which is in turn pivotally connected about an axis P at its other end to one end of a crank lobe 35. The crank lobe 35 is rigidly connected at its other end to a shaft 37 which extends diametrically across the head (through the ducts 10 and 21) at a postion spaced from the doors 24. Attached to one end of the shaft 37, on the exterior of the head, is a manually operable lever 36. The other end of the shaft 37 is rotatably supported.
Referring particularly to Fig. 1, closure of the doors 24 is effected by manually rotating the lever 36 in the direction indicated by the arrow. The crank lobe 35 rotates with the shaft 37 thereby raising the link 34 upwards away from the doors 24. During this action, the pivotal connection between the link 34 and the lobe 35 acts to maintain a generally vertical pull on the springs 30. As the lever 36 is rotated, the doors 24 are raised to close both the inlet 23 and the outlet 16. Once the doors 24 are in position across the inlet 23 and the outlet 16 the lever 36 is further rotated so that the lobe 35 and a link 34 over-centre about the shaft 37, such that the springs 30 are retained in tension, thereby firmly retaining the doors 24 closed across the inlet 23 and the outlet 16. The over-centre action locks the doors 24 in the closed position until they are re-released and opened by counter rotation and lowering.
Various modifications may be made without departing from the scope of the present invention for example, the closing doors could slide across the opening or, more likely, different opening mechanisms could be employed for hinged doors. The springs could be replaced by resilient wires or similar components, or a single spring could be employed attached at its ends to respective lugs 32 on the doors and connected to the 'C' link 34 at its midpoint. Further, the linkage means may comprise a spring or other resilient means attached at one end to the operating assembly and at the other to non-resilient linkages attached to the or respective doors.

Claims

A filling head adapted for insertion into a container to be filled, characterised in that the head comprises at its outlet (16) closure means (24) movable between a first position in which the outlet (16) is open, and a second position in which the outlet (16) is closed, and means for moving said closure means between said first and second positions when the filling head is inserted in the container.
A filling head according to claim 1, characterised in that the head comprises a first duct (10) defining the outlet (16) through which a material may enter the container, and a second duct (21) defining an inlet (23) through which material may enter the head, the closure means (24) being so formed as to close off the said outlet (16) and inlet (23) when in the second position.
A filling head according to claim 2 characterised in that the first and second ducts (10, 21) are concentric with the second duct (21) surrounding the first duct (10).
A filling head according to claim 2 or to claim 3, characterised in that the closure means comprises two semi-circular doors (24) hingedly mounted along their diameters across a diameter of both the inlet (23) and outlet (16).
A filling head according to any preceding claim, characterised in that the means for moving the closure means comprises a manually operable linkage mechanism including resilient means (30) attached to a surface of each door (24) and to a lever-and-crank door operating assembly such that during closure of the outlet (16), the assembly raises the resilient means (30) and consequently urges the doors (24) into the second, closed position.
A filling head according to claim 5, characterised in that the resilient means comprises a spring or springs or a wire.
A filling head according to claim 5 or 6, characterised in that the door operating assembly has an over-centre action to retain the closure means (24) in the second, closed position with the resilient means (30) in tension.
A filling head according to any of claims 5 to 7, characterised in that the door operating assembly comprises a manually operable handle (36) attached to a shaft (37) extending at least partially across the diameter of the head, a crank lobe (35) rigidly fixed to said shaft (37) within the head, and a generally C-shaped link (34) pivotally connected at one end to the lobe (35) and at the other end to the resilient means (30).
A filling head adapted for insertion into a container to be filled, the head comprising a first duct (10) defining an outlet through which a material may enter the container, a second duct (21) defining an inlet (23) through which material may enter the head, and closure means (24) movable between a first position in which the inlet (23) and outlet (16) are open and a second position in which the inlet (23) and outlet (16) are closed.
A filling head adapted for insertion into a container to be filled, the head comprising at its outlet (16) a pair of doors (24) movable from a first open position to a second closed position in which they close off the outlet (16) and means for moving said doors (24) between said open and closed positions, said means incorporating a resilient linkage.