More specifically, the present invention relates to a machine for filling containers with incoherent fill material, of the type comprising an endless conveyor looped about a first and a second wheel to convey the containers along a given conveying path; and a container filling unit; the conveying path comprising a curved filling portion extending about the second wheel and beneath the filling unit, an empty-container loading portion, and a full-container unloading portion; and the loading and unloading portions being located on opposite sides of the filling portion.

BACKGROUND ART In known filling machines of the type described above, the filling portion of the container conveying path is normally a semicircular portion extending along a roughly 180° arc about the second wheel, and the filling unit is normally a volumetric unit, i. e. a unit comprising a succession of dispensing stations, each of which is movable with the second wheel, travels with a respective container along the filling portion, and

dispenses a given volume of fill material into the respective container as the container travels along the filling portion.

Employing volumetric filling units has various drawbacks, on account of the weight of a given volume of material normally varying over a relatively wide range, depending on environmental conditions. And, since a given weight, as opposed to a given volume, of material must be guaranteed inside each container, manufacturers are forced, at considerable cost, to operate in excess, i. e. to calculate volumes so as to guarantee"at least"the declared weight.

Despite the above drawback, volumetric filling units are traditionally preferred, by permitting relatively compact filling machines. That is, the dispensing stations of volumetric filling units, by dispensing the relative volumes of material into the relative containers practically in one go, require relatively short filling paths and, therefore, relatively small-diameter wheels.

Whereas, in the case of a filling unit operating by weight, the material is dispensed gradually and, for the same output rate as an equivalent volumetric filling unit, i. e. for a given travelling speed of the conveyor, requires larger-diameter wheels.

DISCLOSURE OF INVENTION It is an object of the present invention to provide a machine for filling containers with incoherent fill material, which combines the advantages, and eliminates

the drawbacks, of both volumetric and weight filling machines.

According to the present invention, there is provided a machine for filling containers with incoherent fill material, as claimed in Claim 1 and, preferably, in any one of the following Claims depending directly or indirectly on Claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS A non-limiting embodiment of the invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows a schematic plan view, with parts removed for clarity, of a bottom portion of a preferred embodiment of the filling machine according to the present invention; Figure 2 shows a schematic diametrical section of a top portion of the Figure l filling machine; Figure 3 shows a schematic section, with parts removed for clarity, along line III-III in Figure 1 ; Figure 4 shows a schematic view in perspective, with parts removed for clarity, of the Figure 3 detail; Figures 5 and 6 show two cross sections, in planes parallel to the Figure 1 plane, illustrating the Figure 3 and 4 detail in two distinct operating positions; Figure 7 shows a larger-scale view of a detail in Figure 2.

BEST MODE FOR CARRYING OUT THE INVENTION Number 1 in Figure 1 indicates as a whole a filling

machine for filling, with a given incoherent fill material, containers 2 defined by open-topped, substantially parallelepiped-shaped cardboard boxes or similar.

Machine 1 comprises a conveyor 3, in turn comprising two wheels 4 and 5 fitted to a frame 6 to rotate, with respect to frame 6, about respective axes 7 and 8 perpendicular to the Figure 1 plane, and a conveying member 10 looped about wheels 4 and 5, and having a succession of pockets 11, each for receiving and retaining a respective container 2. Machine 1 also comprises a filling unit 9 (Figure 2) located over wheel 5, and for filling containers 2 by weight.

Conveying member 10 feeds pockets 11 along a path P which comprises a curved filling portion P1 extending about part of wheel 5 and beneath filling unit 9; a loading portion P2 extending from a loading station 12 where empty containers 2 are loaded onto conveying member 10 ; and an unloading portion P3 located on the opposite side of filling portion PI to loading portion P2, and which terminates at an unloading station 13 where the full containers 2 are unloaded off conveying member l0.

Wheel 5 is larger in diameter than, and preferably at least twice the diameter of, wheel 4 ; filling portion P1 extends about the periphery of wheel 5 along an arc of over 180° and preferably of about 270° ; and loading portion P2 and unloading portion P3 are straight parallel portions which are tangent to wheel 4, are separated by a

distance substantially equal to the diameter of wheel 4, and are connected to the respective ends of filling portion P1 by respective bends 14 and 15.

In a variation not shown, wheel 4 is offset laterally with respect to wheel 5, and only one of portions P2 and P3 is connected by a bend to filling portion Pl.

As shown more clearly in Figure 2, wheel 5 comprises a cylindrical base body 16 coaxial with axis 8 and fitted to a drive shaft 17 fitted in rotary manner to frame 6.

With reference also to Figures 5 and 6, the top of cylindrical body 16 is fitted by means of studs 18 with an inner ring 19 of an annular body 20 coaxial with axis 8 and comprising an outer ring 21 connected integrally to inner ring 19 by spokes defining a succession of slots 22 between inner ring 19 and outer ring 21. Outer ring 21 is fitted on its outer periphery with two superimposed ring gears 23 for respective chains 24 forming part of conveying member 10 and supporting pockets 11. Each pocket 11 is substantially U-shaped, and comprises an intermediate wall 25 parallel to axis 8, located outside chains 24, and connected to chains 24 by a bracket 26; and, as shown in Figures 4 to 6, two lateral walls 27 connected to the relative lateral edges of intermediate wall 25 by hinges 28, each enabling relative lateral wall 27 to oscillate, under the control of an actuating device 29 and about a respective axis 30 parallel to axis 8, between an open position (Figure 6) and a closed position

(Figure 5) in which lateral walls 27 are parallel to each other to grip and retain between them a relative container 2. As shown in Figure 4, actuating device 29 comprises a fixed cam 31 extending along the whole of path P inwards of chains 24; and, for each lateral wall 27, an arm 32 integral with lateral wall 27 and fitted on its free end with a cam follower 33 movable in contact with cam 31.

In a variation not shown, only one of lateral walls 27 is movable, while the other is fixed.

As shown in Figure 2, wheel 5 comprises a number of weighing devices 34 which are equally spaced about cylindrical body 16 with the same spacing as pockets 11 along conveying member 10, and are synchronized with pockets 11 along filling portion P1.

As shown more clearly in Figure 3, each weighing device 34 comprises a box body 35 fitted to a bottom surface of cylindrical body 16 to project radially outwards of cylindrical body 16, and comprising, outwards of cylindrical body 16, a chamber 36 bounded at the top by a wall 37 and housing a scale 38 having an input member 39 facing upwards, parallel to axis 8 and towards wall 37.

As shown in Figures 3 and 4, each weighing device 34 also comprises two side by side rods 40 which are fitted in rotary and axially fixed manner through wall 37, extend through relative slot 22 and parallel to axis 8, and define a guide for a U-shaped slide 41. Each slide 41

extends through relative slot 22, and comprises two end shoes 42 fitted through with the relative pair of rods 40, which are fitted in rotary and axially sliding manner to each shoe 42. Shoes 42 of each slide 41 are connected to each other by a core 43 parallel to axis 8 and extending in the space between rings 19 and 21. The bottom end, just above wall 37, of each core 43 is fitted with a plate 44 which projects radially outwards of relative core 43 and supports a flat, substantially rectangular plate 45 located beneath a respective pocket 11 and fitted on its bottom surface with a strut 46 which extends through plate 44 and in sliding manner through wall 37, and is fitted at the end to input member 39 of relative scale 38.

Each weighing device 34 also comprises a pocket 47, which is bounded at the bottom by relative plate 45 and defined laterally by two pairs of jaws 48 and 49 of a double gripper 50 fitted to relative slide 41 to move with slide 41 along relative rods 40.

As shown more clearly in Figure 4, each jaw 48 is located over a respective jaw 49, is connected angularly, together with respective jaw 49, to a respective rod 40, is connected to the other jaw 48 by a spring 51, and comprises an end portion defined by a flat contoured plate 52 parallel to relative plate 45 and which engages respective container 2 laterally through a respective slit 53 formed through relative lateral wall 27 of relative pocket 11. Each jaw 49 is similar to relative

jaw 48, is connected to the other jaw 49 by a spring 54 similar to spring 51, and comprises an end portion defined by a flat contoured plate 55 similar to plate 52 of relative jaw 48, and which engages respective container 2 laterally through a passage formed between relative plate 45 and a bottom end of relative lateral wall 27 of relative pocket 11. Both the passages and slits 53 are so sized vertically as to permit a given vertical movement of relative slide 41 and relative gripper 50. Jaws 48 and 49 are moved, in opposition to springs 51 and 54, from a normal closed position (Figure 6) to an open position (Figure 5) by an actuating device 56, which comprises, for each rod 40, an arm 57 housed inside relative box body 35 and fitted to rod 40; and a control rod 58 connected to a free end of relative arm 57 and activated by a known cam device (not shown) to rotate relative rod 40 about its axis with respect to cylindrical body 16 of wheel 5.

As explained in more detail later on, actuating devices 29 and 56 (in particular, the relative cams) are designed to keep each gripper 50 in the closed position along at least part of filling portion P1, and lateral walls 27 of each pocket 11 in an open position, releasing relative container 2, along substantially the whole of said part of filling portion P1.

In a variation not shown, only one of rods 40 is oscillated about its axis to control the position of respective jaws 48 and 49, while the other rod 40 is

angularly fixed together with relative jaws 48 and 49.

Each pocket 47 is therefore free to move with relative slide 41, and within a given range, along relative rods 40, and is supported vertically solely by input member 39 of relative scale 38. Input member 39 is obviously also movable axially in known manner in opposition to known internal measuring members (not shown) of scale 38 to transmit a continuous weight signal to scale 38.

With reference to Figure 2, filling unit 9 comprises a dispensing member 59 mounted over and coaxial with wheel 5, rotating with wheel 5 about axis 8, and which comprises a powered telescopic upright 60 extending upwards from wheel 5 and smaller in outside diameter than inner ring 19; and a head 61 integral with the top end of upright 60. Head 61 comprises a top portion 62 having a conical, upward-tapering lateral surface 63 coaxial with axis 8; and a bottom portion 64 having a cylindrical lateral wall 65 bounded at the bottom by a flat annular wall 66, which is perpendicular to axis 8 and has a peripheral annular portion 67 projecting outwards of lateral wall 65 and having a number of openings 68, each located directly over a respective plate 45.

Filling unit 9 also comprises a substantially cylindrical casing 69 coaxial with wheel 5 and surrounding head 61 to define, with head 61, an annular chamber 70 having a central hole 71 at the top, through which is inserted a feed conduit 72, a bottom edge of

which is located close to lateral surface 63 of head 61 to define, with lateral surface 63, an annular gap 73 coaxial with axis 8 and through which the fill material is fed into chamber 70. Casing 69 has an inside diameter larger than the outside diameter of lateral wall 65 of bottom portion 64 of head 61, and rests on and is welded to an outer edge of peripheral annular portion 67 of wall 66 to define, with annular portion 67 and lateral wall 65, an annular channel 74 communicating with the outside through openings 68.

As shown more clearly in Figure 7, each opening 68 defines a pocket for a relative removable insert 75 having a normally substantially oval-section through hole 76, the size of which depends on the size of containers 2 to be filled. The outlet of each hole 76 is adjustable by means of a respective valve device 77 supported by an annular plate 78 which is fitted integrally to the underside of wall 66, is coaxial with axis 8, projects outwards of casing 69, and has through openings 79, each of which is substantially coaxial with a respective opening 68 and is engaged by a respective insert 75.

Each valve device 77 comprises two opposite actuators 80 which are fitted to annular plate 78 in radially coaxial positions, are controlled by relative scale 38, and activate respective shutters 81 movable to and from a position contacting each other to fully close relative hole 76.

As shown in Figure 2, filling unit 9 also comprises

a known stirring device 82 which is secured in a fixed position to feed conduit 72, and comprises a sloping arm 83 extending inside chamber 70 along conical lateral surface 63 of top portion 62 of head 61, and fitted on its free end with a powered blade 84 engaging channel 74 and rotating about an axis 85 perpendicular to axis 8.

In actual use, containers 2, in the form of flat tubular packages 86, are withdrawn successively in known manner from a stack 87 by a gripper drum 88, and are fed into respective pockets 11 at loading station 12. As it is fed into relative pocket 11, each flat tubular package 86 is"unfolded"in known to form a hollow tubular package and, as it travels along loading portion P2 and through a known folding station 89, is closed at the bottom to form an open-topped, cup-shaped container 2 having upward-facing flaps 90 at the top end.

As it is fed along loading portion P2, each container 2 is engaged laterally by lateral walls 27 of relative pocket 11 in the closed position, and is so retained contacting intermediate wall 25 of relative pocket 11 which, as it travels along bend 14, gradually mates with a relative pocket 47 which receives relative pocket 11 with gripper 50 in the open position (Figure 5). At the start of filling portion P1, gripper 50 is closed onto container 2 and, immediately after, lateral walls 27 are moved into the open position (Figure 6) to release container 2 inside relative pocket 47, resting on relative plate 45, and gripped between jaws 48 and 49 of

relative gripper 50.

In the position described above, container 2 therefore no longer interferes in any way with relative pocket 11 which accompanies it along the whole length of filling portion P1, and the weight of container 2 rests entirely, and with no outside interference, on scale 38 of relative weighing device 34.

At this point, the relative previously closed valve device 77 opens to allow the incoherent material-fed continuously by feed conduit 72 into chamber 70 and evenly distributed by dispensing member 59 along the whole of channel 74-to flow through relative hole 76 and gradually fill relative container 2 as the container travels along filling portion P1. Each scale 38 normally controls relative valve device 77 so that the flow of material through relative hole 76 is fairly considerable to begin with, and is gradually reduced to zero as the weight of the material fed into relative container 2, and monitored continuously by relative scale 38, nears the desired weight, which is normally reached close to the end of filling portion P1.

In connection with the above, it should be pointed out that the arc of over 180°, and of about 270° in the example shown, along which filling portion P1 extends about axis 8 permits relatively long filling times, and therefore relatively precise filling by weight, using a relatively small-diameter wheel 5 and without impairing the operating speed or overall compactness of machine 1.

When container 2 reaches bend 15, lateral walls 27 of relative pocket 11 close to grip container 2 laterally, and relative gripper 50 opens to release container 2 onto conveying member 10, which feeds container 2 through a folding station 91 where flaps 90 are folded and connected in known manner to close container 2. Conveying member 10 then feeds container 2 through a known reject station 92 and to unloading station 13 where, after opening lateral walls 27 of relative pocket 11, the full container 2 is unloaded in known manner off conveying member 10 and onto an output conveyor 93.