Description

Process for moving powdered material, dosing machine for powdered material and system for bagging said material

Technical Field

The present invention relates to a process for dosing powdered material and a dosing machine for powdered material which implements the process, in particular a dosing machine for powdered material such -as cement, lime, carbonate, talc and the like.

The present invention also relates to a system for bagging powdered material .

Background Art

In systems for bagging powdered material, dosing machines are usually installed upstream of packaging or bagging machines and supply the latter with a precise quantity of material to be packaged in each bag. In the case of powdered material, the bags are normally of the type with a valve, that is to say, preformed bags with a tab for insertion of a nozzle from which the material comes out.

Packaging machines of the known type, in general multi-head rotary machines, close between 80 and 120 bags per hour and the respective dosing machines can supply them appropriately.

Valve bags are very expensive, made of paper or fabric and usually filled very slowly, since the powders easily take in air, increasing their volume by up to three times and spreading in the environment . This is why for powdered materials tubular bags are not used, for example made of polyethylene, normally used with granular materials which can be poured into the bag very rapidly.

The tubular bags are produced, in the relative packaging machine, from a reel of tubular polythene material from which a portion of tubular material is taken, which is sealed closed at

one end, filled and closed with another seal at the other end.

Bagging machines which produce tubular bags operate continuously, allowing a significant amount of time to be saved during packaging but cannot be advantageously used with powdered materials since dosing machines of the known type do not allow more than 50 bags per hour to be supplied because the powdered material takes in air during processing, considerably increasing its volume .

Known dosing machines are unable to remove the air from the powder, therefore, the material is moved slowly.

To package each bag, it is necessary to wait until the air leaves the bagged material, allowing the correct quantity of material to be inserted in each bag before sealing it .

Disclosure of the Invention

In this context, the main technical purpose of the present invention is to propose a process for moving powdered material rapidly, in particular to allow rapid bagging of the material and the use of bagging machines for tubular bags . Another aim of the present invention is to propose a dosing machine for powdered material which prepares the doses of material substantially without air, in particular to bag them in sealable tubular bags .

Yet another aim of the present invention is to propose a system for bagging powdered material, for bagging said material in tubular bags .

The technical purpose indicated and the aims specified are substantially achieved by a process for moving powdered material described in claim 1 and in one or more of the dependent claims herein, by a dosing machine for powdered material described in claim 13 and in one or more of the dependent claims and by a system for bagging powdered material described in claim 38 and in one or more of the dependent claims .

Brief Description of the Drawings

Further characteristics and advantages of the present invention are more apparent in the detailed description below,

with reference to a preferred, non-limiting, embodiment of a dosing machine for powdered materials and a system for bagging said material, illustrated in the accompanying drawings, in which:

Figure 1 is a schematic front view, partly a block diagram, of a system for bagging powdered material made in accordance with the present invention;

Figure 2 is an enlarged schematic front view of a portion of the system from Figure 1, with some parts cut away and others in cross-section for greater clarity; Figure 2a is an enlarged schematic front view of detail A from Figure 2, with some parts cut away and others in cross- section for greater clarity;

Figure 3 is a schematic top plan view of the portion of system from Figure 2, with some parts for greater clarity; Figure 4 is an enlarged schematic front view of a second portion of the system from Figure 1, with some parts cut away for greater clarity;

Figure 5 is an enlarged schematic front view of a second embodiment o£ the portion of system from Figure 2, with some parts cut away and others in cross-section for greater clarity;

Figure 6 is an enlarged schematic front view of a preferred embodiment of a weighing device which is part of the system from Figure 1 ;

Figure 7 is a schematic front view of a preferred embodiment of a nozzle for filling bags which is part of the system for bagging powdered material in accordance with the present invention;

Figure 8 is a schematic front view, partly a block diagram, of a second embodiment of a system for bagging powdered material made in accordance with the present invention.

Detailed Description of the Preferred Embodiments of the Invention With reference to the accompanying drawings, the numeral 1 denotes a system for bagging powdered material 2 such as cement, lime, carbonate, talc.

Said system 1 allows implementation of the process for moving the powdered material 2 disclosed. Details of system 1

structure and operation are described below.

The process substantially comprises the steps of inserting the powdered material 2 in a feed path P, depressurising the path P and compacting the material 2 along the path P so that the air with which it is mixed is removed from it.

In particular, the compacting step comprises a step of compressing the material 2; in particular, the material is made to rotate and is pressed against suitable stop means 31.

The step of depressurising the feed path P comprises a step of extracting fluid along the path P using suitable extractor means 18.

Any powdered material 2 extracted during the extraction step is recycled and returned to the path P after being suitably filtered. Moreover, the process preferably comprises a step of weighing the material 2 as it is fed along the path P.

To prevent the material 2 from taking in air as it is fed, preferably by falling, along P, the material 2 is suitably braked.

During insertion of the material 2 in a bag 14, the process comprises a step of extracting fluid from the bag 14.

For improved bag 14 filling, more material 2 than necessary is inserted in it and the excess material 2 is sucked out again by strong depressurisation of the bag 14.

Simultaneously with insertion of the material 2 in the bag 14 the latter is shaken to achieve improved filling.

The system 1 substantially comprises a dosing machine 3 for the material 2 and a bagging machine for the material located downstream of the machine 3 according to a material 2 feed path P.

The bagging machine is schematically illustrated with a ^' block 4, since it is of the substantially known type and only the parts necessary for an understanding of the invention are described below.

The machine 3 extends mainly vertically and is supported by suitable support means, of the substantially known type and not illustrated.

As illustrated in Figure 1, the machine 3 comprises means 5 for containing the material 2 to be bagged.

The container means 5 are supplied in the substantially known way, during system 1 operation, through a loading mouth 6 communicating by means of a pipe 7 with a material 2 storage silo, not illustrated. The container means 5 have a sensor 56, preferably of the paddle type, for the minimum level, and a sensor 57, preferably of the paddle type, for the maximum level.

The sensors 56 and 57 monitor the quantity of material 2 present in the container means 5. Downstream of the container means 5 according to the material 2 feed path P towards the bagging machine 2 , the machine 3 comprises material 2 weighing means 8.

In particular, the weighing means 8 are connected to the container means 5 by jointed connecting means 9. The jointed connecting means 9 allow the weighing means 8 to slide freely relative to the container means 5 during material 2 weighing, so that it is not affected by the upstream means 5.

As illustrated in particular in Figure 2, the jointed connecting means 9 comprise, for example, a funnel 91 slidably inserted in a mouth 92, at the weighing means 8 infeed, forming a sliding male - female connection.

The outflow of material 2 from the container means 5 towards the weighing means 8 is regulated by unloading means 10, described in more detail below, which are mobile between a position in which the container means 5 are closed and at least one position in which they are open.

The outflow of material 2 from the weighing means 8 towards the bagging machine 4 is regulated by second gradual opening unloading means 11 connected to the weighing means 8. Downstream of the dosing machine 3, the system 1 comprises an unloading hopper or pipe 12 for conveying the material 2 from the dosing machine 3 to the bagging machine 4.

The latter has a filling pipe 13 or nozzle in communication with the hopper 12 for filling the bags 14. It should be noticed that the hopper 12 is connected to the gradual opening means 11 by second jointed connecting means 15 which allow the weighing means 8 to move freely relative to the

hopper 12, so that material 2 weighing is not affected by the downstream hopper 12.

As illustrated in Figure 4, the bagging machine 4 comprises conveyor means 16 which feed the bags 14 along a sorting path substantially transversal to the material 2 descent path P.

There are active agitator means 17 at the bag 14 conveyor means 16, to optimise bag 14 filling, as described in more detail below.

The system 1 has extractor means 18 operating at the feed path P to substantially keep the path P at least partly in a vacuum.

It should be noticed that the material 2 preferably descends from the container means 5 as far as the bagging machine 4 by falling and the extractor means 18 are designed to prevent the powders from being dispersed outside of the system 1.

In the preferred embodiment illustrated, the means 18 comprise an extractor 19, in fluid communication with the dosing machine 3 and the bagging machine 4.

In particular, in the solution illustrated in Figure 1, the means 18 comprise an extractor pipe 20 positioned, along the path P, downstream of the container means 5 and upstream of the weighing means 8.

The pipe 20 is preferably positioned substantially at the filling mouth 91 of the weighing means 8. The means 18 also comprise a second extractor pipe 22 positioned downstream of the weighing means 8, substantially at the second jointed connecting means 15.

Advantageously, the extractor pipes 20 and 22 prevent powders from coming out of the weighing means 8, allowing a very precise measurement without obstructing the oscillations of the weighing means 8, described in more detail below.

A third extractor pipe 23 operates at the nozzle 13, close to the bag 14 opening.

A fourth pipe 24, which is part of the extractor means 18, is preferably located at the nozzle 13, close to the bag 14 opening, on the opposite side to the pipe 23, to guarantee a stronger vacuum, as is explained in more detail below, when the

bag 14 is being filled.

The system 1 also comprises choke means, schematically- illustrated with a block 54 connected to the extractor means 18.

Said choke means 54 allow the vacuum in the pipes 23 and 24 to be increased when the bag 14 is being filled, in particular when it is substantially full, as described in more detail below.

In the preferred embodiment illustrated, the means 54 comprise a plurality of gate valves, not illustrated, which regulate the fluid currents in the extractor means 18. The system 1 preferably comprises powder filter means 25 having an inlet 26 in fluid communication with the extractor means 18 to recover material dispersed during feed along the path P.

In particular, the filter means 25 have an outlet 27 in communication with the container means 5 to form a closed recycling path for material 2 dispersed or extracted by the extractor means 18.

In the preferred embodiment illustrated, the filter means 25 comprise a body 250 containing a plurality of filter elements

(filters) 251 to prevent dispersion in the outside environment of the powdered material 2 extracted by the extractor means 18 and to allow said material to be recirculated.

As illustrated in Figures 2 and 3 , the machine 3 comprises material 2 compacting means 28 positioned inside the container means 5. The means 28 are designed to compact the material 2 before feeding it along the path P towards the bagging machine 4.

In particular, the means ^' 28 compress the powdered material 2 to remove the air trapped in it which significantly increases its volume . In the preferred embodiment illustrated, the compacting means 28 comprise a rotary element 29, which can rotate about an axis R in the direction V.

The rotary element 29 is driven by a motor unit 30 of the substantially known type by means of a shaft 30a. In the preferred embodiment illustrated, the stop means 31 are formed by a panel against which the material 2 fed by the rotary element 29 is pressed.

The container means 5 preferably consist of a substantially cylindrical container 32, which allows a fluid movement of the material 2 inside it.

Moreover, the rotary element 29 preferably consists of a cone 33.

The cone 33 is preferably right and has an axis substantially coinciding with the axis R.

The conical shape of the element 29 allows the material 2 to slide under the effect of gravity along the side surface 34 of the cone 33.

As illustrated, the panel 31 consists of a bar 35 positioned transversally relative to the cone 33 and with the ends 36, 37 at different heights relative to the cylinder 32.

In particular, the lower end 37 is positioned at a material 2 unloading opening 38 in the cylinder 32 communicating, by means of the unloading means 10, with the weighing means 8.

The material 2 is made to rotate by the cone 33 and is compressed against the bar 35 due to the rotary movement, removing the air trapped in it. Once compacted, that is to say, when the air has been removed from it, the material 2 is unloaded into the weighing means 8.

The machine 3 comprises pusher means 39 positioned in the cylinder 32 to promote the outflow of the material 2 through the opening 38.

The pusher means 39 comprise a plurality of rotary blades 40 positioned at the base of the container means 5.

In particular, the blades 40 are connected to the bottom of the cone 33 and can rotate with the cone. The blades 40 substantially extend as far as the side wall 41 of the cylinder 32.

Each blade 40 has a chamfer 401 for improved material 2 pushing .

Advantageously, in alternative embodiments not illustrated, the pusher means 39 comprise a greater or lesser number of blades 40 depending on the type of material 2 moved.

As illustrated in Figures 2 and 2a, the unloading means 10

comprise a valve 42 mobile between a position in which the opening 38 is closed, illustrated in Figure 2a, and a first and a second open position, illustrated in Figure 2 respectively with a continuous line and a dashed line. The first and second open positions are distinguished from one another in that the first is for unloading a large quantity of material 2 and the second is for finishing unloading.

The valve 42 is preferably operated by control means 43 of a substantially known type, for example pneumatic or electro- mechanical.

As illustrated in Figure 4, the weighing means 8 comprise means 44 for braking the material 2 falling along the path P, to reduce the material 2 flying time, so .that it does not absorb air.

In particular, the weighing means 8 comprise a hopper 45 with an angled inner wall 46, forming the braking means 44.

In the preferred embodiment illustrated, the hopper 45 has the shape of an off-centre truncated cone to promote material 2 falling.

A plurality of load cells 47 are connected to the hopper 45 to weigh its contents in a substantially known way.

The gradual opening means 11 comprise a pinch valve 48.

The bottom of the hopper 45 is closed by the pinch valve 48 to substantially form a weighing tank.

The pinch valve 48, operated in a substantially known way by a pair of pneumatic actuators 49, allows gradual opening of the hopper 45.

The pinch valve 48 may be opened slowly and is precise as regards the quantity of material it allows to pass .

As illustrated in Figure 4, the system 1 comprises bag 14 retaining means 51, operating when a bag is filled, as described below.

The means 51 are mobile between a position in which they retain the bag 14 and a home position, not illustrated, which allows the bag to be fed along the sorting path. In practice, the powder 2 is supplied in a known way to the cylinder 32 by means of the pipe 7.

Inside the cylinder the cone 33 causes the material 2 to

rotate and, gradually, removes the air from it by pressing it against the bar 35.

The valve 42 is periodically opened to allow the compacted material 2 to pass into the weighing means 8; the pusher means 39 promote material 2 feed towards the opening 38, in particular if it is very compact, which makes feed under the effect of gravity difficult.

It should be noticed that during this step a first part of the material 2 descends rapidly, with the valve in the first open position, completely distanced from the opening 38, then a last part (preferably the last second of valve 42 opening) falls with the valve 42 in the second open position, close to the opening 38 for improved control of the weight of the material 2 unloaded.

Moreover, this second open position guarantees a substantially immediate speed for closure of the opening 38.

In this way, the material 2 which descends into the weighing means 8 is substantially compact, without taking in air.

As illustrated in Figure 5, the unloading means 10 comprise a gate valve 100 comprising a sliding element 101 which is mobile between a position in which the container 32 is closed and a position in which it is open, illustrated with the dashed line.

The valve 100 is preferable for moving materials 2 which do not flow well, since it can "cut off" the flow of material 2 coming out of the container 32. Between the closed position and the open position there is preferably a finishing open position, where the material 2 is free to flow through a crack 102 delimited, at the unloading opening 38, by a lower edge 103 of the sliding element 101 and by the base wall of the container 32. The angled wall 46 significantly reduces the flying time of the material 2 which rests on the wall as soon as it comes out of the opening 38, substantially without taking in air.

Once it has been weighed in a substantially known way by the load cells 47, the powder 2 is allowed to move towards the nozzle 13 where bagging takes place.

It should be noticed that during the descent the material 2 moves along the path P which is substantially in a vacuum.

In this way the powder 2 is not dispersed in the surrounding environment and the material 2 does not swell, remaining easy to bag.

Moreover, advantageously, any powders which do escape are recovered by the extractor means 18 and put back into the machine 3 through the filter means 25.

As illustrated in Figure 6, the extractor means 18 comprise a fifth pipe 104 in fluid communication with the inside of the weighing hopper 45. In particular, the hopper 45 has a lid 105 through which the pipe 104 is in communication with the inside of the hopper 45.

The lid 105 has an opening 106 where a connector 107 is applied. The pipe 104 is loosely inserted on the connector.

The connector 107 is such that the pipe 104 draws near the hopper 45 substantially horizontally to avoid disturbing weighing operations .

The bagging machine 4, in the substantially known way and therefore not illustrated, prepares the tubular bag 14 by taking it from a wound up reel, seals one end of the bag and feeds it along the sorting path, holding it with suitable gripping means, schematically illustrated with a block 55, at a filling opening.

It should be noticed that such a type of bagging machine is referred to by way of example; the dosing machine 3 may be connected to any known type of bagging machine; similarly the machine 3 can be used to weigh raw materials intended for subsequent processing.

In particular with reference to Figure 4, the preformed bag 14, illustrated with a dashed line, remains compressed and preferably in a controlled vacuum until the subsequent filling. The empty bag 14 is then joined in the known way to the nozzle 13 through which the material 2 enters the bag 14 to fill it.

During this step the bag 14 suddenly swells and the retaining means 51 keep it balanced. As illustrated in Figure 7, the nozzle 13 comprises an outer covering 108, having an inlet 108a and an outlet 108b, connected to the unloading hopper 12, and an inner tube 109 through which

the material 2 flows towards the bag 14.

The outer covering 108 and the inner tube 109 form a substantially tubular hollow space 110 connected to the extractor 19. In the preferred embodiment illustrated, the tube 109 is mounted in such a way that it projects on the hopper 12 by suitable support means 111.

The tube 109 is preferably made of a material which guarantees optimum flowing of the powders processed. By way of example, the tube 109 is made of PVC.

During the bag filling step, the agitator means 17 shake the bag 14 to promote insertion of the material 2.

In the preferred embodiment, the agitator means 17 comprise first and second vibrator means 52, 53 rotating in opposite directions in such a way that their line of action is substantially vertical.

During shaking the extraction power is significantly increased in the pipes 23 and 24 or in the hollow space 110, through the choke means 54, so that the bag 14 tends to be compressed and to take on a shape which is easy to palletise.

In particular, in the embodiment in Figure 7, the extraction through the hollow space 110 substantially maintains the vacuum in the bag 14 facilitating its filling.

It should be noticed that to compensate for losses of material 2 from the bag at the moment of this latter strong extraction, the machine 3 is calibrated to insert in the bag 14 more material 2 than required so that when the bag 14 is closed the necessary quantity is inside it.

At the end of filling the retaining means 51 release the bag 14 which is conveyed in the known way onwards for closing and storage .

As illustrated in Figure 8, the hopper 45 has an inner coating 112 which facilitates material 2 flowing.

For powdered material, the coating 112 is preferably made of PVC .

The unloading hopper 12 has an inner coating 113 to facilitate material 2 flowing.

Advantageously, the coating 113 is made of PVC.

The invention brings important advantages .

The material falling along a path in a vacuum prevents it from taking in air and increasing in volume, thus allowing it to be bagged in plastic bags, which cannot normally be used for such materials .

The material is compacted twice, at the start of its path along the dosing machine, by compressing, and in the bag, by a strong extraction and the shaking which allow the powdered material to be packed in bags, for example made of polythene, which can be sealed on each side .

Use of such bags allows a significant economic saving compared with the usual use of valve bags for powdered materials.

The plastic bags can be recycled, can be stored in the open and do not lose material, which occurs with unsealed valve bags.

The invention described has evident industrial applications and may be modified and adapted without thereby departing from the scope of the inventive concept. Moreover, all details of the invention may be substituted by technically equivalent elements .