MACHINE FOR PRODUCING FILTER-BAGS WITH INFUSION PRODUCTS AND WITH AN OVERWRAP ENVELOPE Technical field

This invention relates to a machine for forming filter-bags containing infusion products and with an overwrap envelope.

The expression "infusion products" means products such as tea, coffee, camomile (in powder, granules, or leaves).

Background art

Each filter bag contains at least a dose of product enclosed in a corresponding lobe of the filter bag. The filter bag comprises a piece of filter material and may be for example single-lobed or double-lobed. The piece of filter material of the single-lobed type defines a chamber designed to contain a dose of product, whilst the piece of filter material of the two- lobed type defines two chambers designed to contain two respective doses of product.

In the case of a two-lobed bag, the two chambers with doses are folded towards each other forming a single upper end (in the shape of an upturned "V") and a bottom end in the shape of a "W.

There are prior art machines for packaging (in a stepwise fashion) a plurality of wrapped filter-bags, in particular of the above-mentioned two- lobed type.

More specifically, these machines each form filter-bags through the handling of a piece of filter material, suitably folded, and (if present) of a sheet of overwrapping material which surrounds the folded piece.

Each packaged bag may comprise, in addition to the folded piece, a thread and, if necessary, a label. The thread, by means of knotting, connects the piece of folded filter material to the label. The automatic machines forming this type of the filter bag comprise, amongst other things, a rotary carousel equipped with a plurality of grippers each of which is designed to adopt a retaining condition and a releasing condition of a respective bag. The carousel rotates about an axis of rotation (usually horizontal), in such a way as to cause a movement of each of the grippers along an operating path (arc-shaped/circular), so that each respective bag is transported by the respective gripper along the path, whilst it is retained by the corresponding gripper.

For simplicity, from when a generic piece of filter material in a tubular shape and containing the two doses of infusion product enter into the operating path it may be known as the "filter bag". The filter bag, when it leaves the operating path, and once it has been subject to a plurality of operating steps, may then be called "packaged filter bag".

The features described below with reference to a "respective bag" are to be considered applicable to each filter bag of the plurality of bags which the machine is configured for packaging.

The machine comprises a plurality of stations distributed along the operating path to perform respective operating steps on the respective bag.

The machine is configured in such a way that the carousel rotates in a stepwise fashion, in such a way that the respective bag is, in sequence, in each of these operating stations and for a certain interval of time, so as to be subjected to the respective operating step.

One of these stations may be, for example, an infeed station to allow the entrance of a piece of filter material, from which is derived the respective filter bag, in this operating path.

The infeed station can also perform, advantageously, the folding of the piece, in such a way that the piece is already folded at the start of the operating path defined by the carousel.

Another of these stations may be, for example, an station for application of the thread and/or a label. Another of these stations may be, for example, a knotting station for knotting the thread to the respective piece and/or to the label.

Another of the stations is a wrapping station configured to operate, on the respective bag, at least according to a wrapping mode, in accordance with which the respective bag is picked up by the respective gripper, wrapped in a respective sheet of overwrapping material fed by respective unwinding means, and repositioned in the respective gripper.

The wrapping station, comprises gripping means (usually a further gripper) controlled by a first mechanical cam unit able to orient the gripping means towards and away from the gripper of the carousel and a second mechanical cam unit, in a synchronised fashion with the first cam unit, to allow the gripping by the gripper of the bag and a subsequent release of the bag wrapped by the sheet of overwrapping material always to the same gripper.

Another of these stations may be, for example, a joining station, configured to cause the closing the sheet of overwrapping material positioned around the bag.

After the joining station, it may be said that the respective bag has become, together with the thread, label and the sheet of overwrapping material, a packed overwrapped filter bag.

Usually, the machine also has one or more sensors which are able to detect whether the filter bag, whilst it is moved between these stations or whilst it is in one of them, or in any case whilst it is located along the operating path, has at least one defect. The at least one defect, in the production process of the machine, may require, normally, the rejection of the filter bag itself.

The defect may relate to any component applied during the operating path, therefore, the piece of filter material, the doses of infusion product, the thread and/or the label, for example their mutual arrangement and/or any incorrect knotting.

If the filter bag does not have any defect such as to require the rejection, the packaged filter bag exits from the operating path through an outfeed station, which typically directs it, for example, towards a stacker. If, on the other hand, at least one defect has been detected such as to require the rejection, the packaged filter bag is carried to a rejection station, which typically determines the ejection from the production line.

Basically, the filter bag to be rejected remains on the carousel until reaching a position along the path in which there is an ejector device.

A problem which the machine has is due to the fact that the wrapping station is configured so as to provide for the wrapping, by means of the sheet of overwrapping material, even on a defective filter bag, which will then be rejected.

This activity, so to speak mandatory, of the wrapping station even on a defective bag is due to the connection of the two mechanical cam units acting on the gripping means which, in effect, are interconnected with the remaining servo-mechanisms present on the carousel and in the other stations which create an automatic mechanism during the wrapping steps, irrespective of whether the bag is considered as a correct packaging or as a defective bag.

This situation determines, above all, the waste of the sheet of overwrapping material which is used to wrap the defective bag, as the bag, even if wrapped by the sheet, will in any case be rejected.

In addition, the continuation of the packaging of the defective filter bag may result, during all the operating steps performed by the stations of the machine (after the operation in which the defect is created), in damage to one or more components of these stations, which operate, automatically, on this defective bag.

More specifically, the operation for joining (sealing) between the sheet of overwrapping material and the defective filter bag by the joining station is risky, since this may cause the dispersion of residue deriving from the filter paper of the folded piece and/or from the label and/or from the infusion material. The dispersion may cause soiling such as to require and/or cause the total stoppage of the machine to allow the cleaning of the station in question.

Prior art machines for forming filter-bags are, for example, described in patent document D1 (EP1 173364 A1 ) and in patent document D2 (EP1 189810).

Disclosure of the invention

An aim of this invention is to provide an automatic machine for packaging filter-bags each wrapped by a sheet of overwrapping material which overcomes the above-mentioned drawbacks.

A further aim of this invention is to provide an automatic machine for packaging filter-bags each wrapped by a sheet of overwrapping material which is able to reduce the waste of material for the sheets of overwrapping material and increase the functional safety of the machine. Another aim of this invention is to provide an automatic machine for packaging filter-bags each wrapped by a sheet of overwrapping material which is able to maintain the operating steps necessary for packaging filter-bags and is simultaneously able to actuate various operations on the defective filter-bags within the operating steps set up.

A further aim of this invention is to provide a method for packaging filter- bags each wrapped in a sheet of overwrapping material which detects at least one defect present in any bag positioned along the operating path of the machine and at the same time is also able to reduce the waste of sheets of overwrapping material, avoiding the wrapping of the defective bag which is subsequently rejected.

A further aim of this invention is to provide a method for packaging filter- bags each wrapped in a sheet of overwrapping material which avoids damage to the machine used to perform the packaging, despite the presence of one or more defective bags being processed along the operating path of the machine.

These aims are fully achieved by a machine and a method having the features resulting from any combination of one or more of the appended claims, relating, respectively, to the machine and method.

Brief description of the drawings

The features of the machine and the corresponding method are described in detail below relating to respective embodiments of the machine and method, described by way of a non-limiting example of the more general technical concepts claimed.

The detailed description which follows relates to the accompanying drawings, in which:

- Figure 1 shows a general diagram of a possible embodiment of a machine according to this invention, configured to perform a series of operating steps on each bag of a plurality of filter-bags;

- Figures 2a to 2f show respective sub-steps of an operating step performed by a specific station of the machine, according to a first mode according to which this operating step may occur;

- Figures 3a to 3d show respective sub-steps of the operating step performed by the specific station of the machine, according to a second mode according to which this operating step may occur.

Detailed description of preferred embodiments of the invention

As illustrated, in particular in Figure 1 , this description relates to a machine for packaging filter-bags each wrapped in a sheet of overwrapping material. In this description, the filter bag illustrated is of the two-lobed type purely by way of example and without restricting the scope of the invention.

This filter bag contains two doses of infusion product housed in corresponding chambers. The two chambers are folded towards each other forming a single upper end (in the shape of an upturned "V") and a bottom end in the shape of a "W".

As illustrated, the machine is denoted in its entirety by the numeral 1 . The machine 1 comprises a control system, which may perform control functions for one or more of the components of the machine 1 . The control system is configured in such a way that all the operations and/or movements which are described below can be performed automatically and in predefined sequences.

For this purpose the control system comprises:

- one or more motors and, if necessary, one or more actuators associated with one or more components of the machine 1 ;

- one or more control units for controlling these motors and/or several actuators;

- one or more sensors configured for sending signals entering the one or more control units.

The control system also allows the setting up of at least one or more parameters for setting up the control by the user, for example through at least one interface.

The machine 1 comprises a fixed frame, not shown, relative to which all the movements described below occur, and which supports one or more of the components described below.

A filter bag 4 is shown in Figures 2a to 2f. As will be described in more detail below, the filter bag 4 is deemed to not have any defect such as to require the rejection.

Another filter bag 4' is shown in Figures 3a to 3d. As will be described in more detail below, the filter bag 4' is deemed to have at least one defect such as to require the rejection.

The following considerations, when made with reference to a generic bag

4, are deemed to be also applicable to a bag 4', unless stated otherwise for the case in which the bag is defective.

The machine 1 comprises a rotary carousel 2 that rotates about an axis (preferably horizontal).

The rotary carousel 2 is equipped with a plurality of grippers 3 each of which is designed to adopt a retaining condition in which it is designed to retain a respective bag 4.

Each gripper 3 is designed to adopt a release position, wherein it is not designed to retain a respective bag 4, and in particular it is designed to release it in the case it was previously retained by it.

Figure 1 indicates only some of the grippers 3, whilst the other drawings indicate only a specific gripper 3 which is located in a predetermined position of the machine 1 .

Each gripper 3 may comprise, for example, two retaining portions, labelled 3a and 3b, which may adopt a mutual close position and a spaced apart position.

When the retaining portions 3a and 3b (prongs) are in a mutual close position, the gripper 3 is in its retaining condition, as for example in Figures: 2a, 2e, 2f, 3a, 3c and 3d.

When the retaining portions 3a and 3b are in a mutual spaced apart position, the gripper 3 is in its release condition, as for example in Figures: 2b, 2c, 2d, and 3b.

The relative movement between the retaining portions 3a and 3b of the gripper 3, such as to cause the passage from the retaining condition to the release position, is indicated generically by the arrows X of Figure 1 . The relative movement between the retaining portions 3a and 3b of the gripper 3, such as to cause the passage from the release condition to the retaining position, is generically opposite to the arrows X of Figure 1 .

Even though Figure 1 indicates two arrows X, the relative movement between the retaining portions 3a and 3b, which causes the mutual moving towards or away, may be a movement which, with respect to a system fixed relative to the frame of the machine 1 , affects only one of the retaining portions 3a and 3b.

The carousel 2 rotates in the direction which is suitable for rotating about an axis of rotation R (preferably horizontal). The rotation of the carousel 2 causes a movement of each of the grippers 3 along an operating path.

The direction of travel of the path by each of the grippers 3, caused by the rotation of the carousel 2, may be considered substantially along the edge of the carousel 2 and, in Figure 1 , in a anticlockwise direction.

The movement of each of the grippers 3 in such a way that each respective bag 4 is transported by the respective gripper 3 along the path. The machine 1 comprises a plurality of stations distributed along the operating path P, shown schematically as blocks 5a to 5g. Each of these stations 5a to 5g is configured to perform at least one relative operating step on each bag 4 one after the other.

The number of processing stations may be different from that illustrated in the accompanying drawings and, similarly, the operating steps described below may be different from those which are described.

The position of the stations 5a to 5g of Figure 1 are non-limiting examples.

The stations 5a to 5g are arranged around the carousel 2 translated in an anticlockwise direction to allow better viewing of the components of the station 5d, but their angular positions relative to the carousel 2 may be different from that described, without thereby limiting the scope of the invention.

The machine 1 is configured to rotate the carousel 2 in a stepwise fashion, and therefore in a discontinuous manner, in such a way that each bag 4 can be in sequence in each of the operating stations 5a to 5g, for a certain length of time which can allow the performance of the respective operational step. The stepwise rotation of the carousel 2 also means that at each step several bags 4 transported by respective grippers 3 are simultaneously in several respective operating stations 5a to 5g, in such a way that the machine 1 simultaneously performs several respective operational steps on several respective bags 4.

The first station 5a may be configured to allow the entrance of a piece of filter material in a, for example, tubular configuration (that is, for example, closed by a longitudinal seal and having inside it, in one example, two doses of infusion product), from which is obtained a respective bag 4, in the operating path. Each piece of filter material (hereafter referred to only as piece for simplicity of description), from when it enters the operating path of the carousel 2, can be considered to be a respective filter bag 4.

At the level of an example, the second station 5b may be configured to perform the winding of at least one stretch of thread to the respective bag 4 with relative knotting of an end of the thread to the top (folded) of the bag 4.

The third station 5c may be configured to perform the positioning of the label on the top of the bag 4 and the relative knotting between the other end of the thread and the label with its simultaneous association with the top of the bag 4.

The fourth station 5d is a wrapping station configured to operate, on each respective bag 4, at least according to a wrapping method or according to a rejection method.

The wrapping station 5d, in the embodiment shown of the machine 1 comprises a gripping unit 9, means 6 for unwinding a piece or web of heat- sealable film, and a system 10 for moving the gripper element 9.

The operating station 5e after the wrapping station 5d is a station designed to perform an operating step in which the sheet of overwrapping material F is closed, by sealing, around the filter bag.

Lastly, the station 5g is used, as described in more detail below, as a rejection station for ejection of a defective bag, whilst the station 5f is used, as described in more detail below, as an outfeed station for the outfeed of a packaged bag which is not defective.

After returning to the wrapping station 5d, during its operating step, if this occurs according to the wrapping mode, the bag 4 is:

- picked up by the respective gripper 3, as shown in Figures 2a to 2c;

- wrapped in a respective sheet of overwrapping material F fed by unwinding means 6, as shown in Figure 2d;

- repositioning in the respective gripper 3, as shown in Figures 2e and 2f.

The unwinding means 6 are configured for feeding a web N from which is obtained the sheet of overwrapping material F. The sheet F is a portion of the web N which surrounds the bag 4. The portion of the web N, is separated, preferably during the wrapping or before the wrapping from the remaining part of the web N, in such a way as to make the respective sheet of overwrapping material F which surrounds the respective bag 4. During the operating step performed by the wrapping station 5d, if this occurs according to the rejection mode, the bag, which is now that indicated with the numeral 4', since in that case it is to be considered as having at least one defect such as to require the rejection, is kept in position in the respective gripper 3, or relative to the respective gripper 3. According to this reject mode, the unwinding means 6 are deactivated. The unwinding means 6 preferably comprise a feed and/or unwinding device.

The control system of the machine 1 is configured to operate the wrapping station 5d according to one of these modes.

The control system is configured to operate the wrapping station 5d according to one or the other of these mode on the basis of and/or as a function of at least one detection of at least one defect in the respective bag 4 or 4', the at least one defect being such as to require the rejection of the bag 4'. The type of defect which is such as to require the rejection of the respective bag 4' is set by the user, using the selections in terms of configuration of the control system and/or by means of the setting parameters set by the user and "entered" in the control system.

Figures 2a to 2f illustrate the wrapping mode of the operating step performed by the wrapping station 5d, and, therefore, the bag labelled 4 is to be considered as not defective. Figures 3a to 3d illustrate the rejection mode of the operating step performed by the wrapping station 5d, and, therefore, the bag labelled 4' is to be considered as defective at least at a level such as to require the rejection.

The machine control system comprises at least a sensor 7. In the case illustrated there are one or more sensors, for example, three, 7, 7', 7", distributed between the operating stations 5a to 5c. The control system comprises at least one control unit 8, operatively interposed between the at least one sensor 7 and the at least one wrapping station 5d.

The sensor 7 is operatively active in at least one detecting point P situated along the operating path defined by the carousel 2. The sensor 7 is therefore mounted in the machine 1 in such a way as to be designed to detect the at least one defect in a bag 4 or 4' transiting or at least positioned at the detecting point P.

Figure 1 shows the further sensors 7' and 7" operating in the respective detection points P' and P".

In the embodiment of the machine 1 according to the accompanying drawings, the at least one detection point P is situated between the application station 5b and the knotting station 5c.

The detection point P might be in any other position along the operating path. In any case, once the bag 4 or 4' starts to be subjected to the operating step of the wrapping station 5d, the at least one possible defect must have been detected by at least one sensor.

The sensor 7 is configured to generate at least one detection signal U indicating at least a possible defect present in the respective bag 4 or 4'. The control unit 8 is configured to receive the at least one detection signal U and to send to the wrapping station 5d at least one control signal C. The at least one control signal C is designed to operate the wrapping station 5d according to this wrapping mode or according to this rejection mode. The control signal C is a function at least of the detection signal U.

If the detection signal U is not indicative of the presence of at least one defect such as to require the rejection of the filter bag 4, then the control signal C is designed to ensure that the wrapping station 5d performs its operating step, on the non-defective bag 4, according to the wrapping mode.

If the detection signal U is indicative of the presence of at least one defect such as to require the rejection of the filter bag 4' which comprises the defect, then the control signal C is designed to ensure that the wrapping station 5d performs its operating step, on the defective bag 4, according to the rejection mode.

In this way, there is no waste of the sheet of overwrapping material F for wrapping a defective filter bag 4'.

As already mentioned, the operating station 5e after the wrapping station 5d is a station designed to perform an operating step in which the sheet of overwrapping material F is closed and joined around the filter bag 4.

In the case of a defective filter bag 4' (not wrapped by a sheet of overwrapping material F), the joining station 5e can equally operate when the defective filter bag 4' is in the same joining station 5e, without any drawbacks, thanks to the absence of a sheet of overwrapping material F around the defective filter bag 4', which is not affected by sealing units present in the joining station 5e.

Avoiding the wrapping of the defective bag 4' with a sheet of overwrapping material F not only saves material of the overwrapping material web N, but it also eliminates the risk that one or more components of the machine 1 are damaged and/or that undesired residues are produced due to the breakage of one or more components of the defective bag 4', since the fact that the sheet F is absent, as regards the defective bag 4', means that these drawbacks are avoided.

In an example embodiment of the machine 1 , the wrapping station 5d comprises a pickup unit 9 designed to adopt a gripping condition, in which it is designed to grip a bag 4, and a release position, wherein it is not designed to grip the bag 4. in particular it is designed to release it.

The pickup unit 9 may comprise, for example, two prongs or gripping portions, labelled 9a and 9b, which may adopt a mutual close position and a spaced apart position.

When the gripping portions 9a and 9b are in a mutual position where they are close together, the pickup unit 9 is in its gripping condition, as for example in Figures: 1 , 2b-2f and 3b-3d. When the gripping portions 9a and 9b are in a mutual position where they are spaced apart, the pickup unit 9 is in its release condition, as for example in Figures 2a and 3a.

The relative movement between the gripping portions 9a and 9b of the pickup unit 9, such as to cause the passage from the gripping (or retaining) condition to the release position, is indicated generically by the arrows Y of Figure 1. The relative movement between the gripping portions 9a and 9b of the pickup unit 9, such as to cause the passage from the release condition to the gripping condition, is generically opposite to the arrows Y of Figure 1 .

Even though Figure 1 indicates two arrows Y, the relative movement between the gripping portions 9a and 9b, which causes the mutual moving towards or away, may be a movement which, with respect to a system fixed relative to the frame of the machine 1 , affects only one of the retaining portions 9a and 9b.

The pickup unit 9 is designed to be positioned in a proximal position and in a distal position with respect to each respective gripper 3, when the respective gripper 3 is operatively positioned along the operating path, at the wrapping station 5d.

This distal position is shown in Figures 1 , 2c, 2f and 3d. The proximal position is shown in Figures 2b, 2d and 2e, as well as in Figures 3b and 3c. Figures 2a and 3a show the pickup unit 9 in an intermediate position between the proximal position and the distal position, and Figures 2a and 3a show it moving from the distal position to the proximal position. Moreover, Figures 2a and 3a show the pickup unit 9 whilst it is passing from its release condition to its gripping condition.

In the embodiment of the machine 1 shown in the drawings, the movement from the distal position to the proximal position of the pickup unit 9 is indicated generically by the arrow Z of Figure 1 . The movement of the pickup unit 9 from the proximal position to the distal position is generically opposite the arrow Z of Figure 1. In Figure 1 , the pickup unit 9 is to be considered in a distal position relative to the gripper, amongst the grippers shown in Figure 1 , which is, in the situation of Figure 1 , at the wrapping station 5d, and which is one of those indicated in Figure 1.

The machine 1 comprises a movement system 10 configured for causing a movement of the gripping unit 9 from the distal position to the proximal position and vice versa.

The movement system 10 is also configured to cause the passage of the pickup unit 9 from its release condition to its gripping condition and vice versa.

The movement system 10 is configured to cause the passage of the pickup unit 9 from its release condition to its gripping condition or vice versa, even at least partly simultaneously with the movement of the pickup unit 9 from its position distal to its proximal position and/or from its position proximal to its distal position.

In the embodiment of the machine 1 shown in the accompanying drawings, the movement system comprises at least one cam unit 10a. The at least one cam unit 10a (preferably of a mechanical type) is designed to rotate about an axis of rotation R', which is preferably parallel to the axis of rotation of the carousel 2.

In the embodiment of the machine 1 shown in the accompanying drawings, the movement system 10 comprises a kinematic transmission mechanism 10b (preferably an electric cam) operatively interposed between the at least one cam unit 10a and the pickup unit 9 and interacting with the cam unit 10a.

Preferably, the transmission mechanism 10b is configured so as to cause the movement of the pickup unit 9 from its distal position to its proximal position or vice versa.

This movement is synchronized with the rotation of the cam unit 10a designed to cause the passage of the pickup unit 9 from its release condition to its gripping condition or vice versa. The at least one cam unit 10a may for example comprise a double cam or a desmodromic cam.

Thanks to the cam unit 10a and transmission mechanism 10b, the movement system 10 is configured to ensure that each actuation of the transmission mechanism 10b (and rotation of the cam unit 10a, in at least a first angular interval) corresponds with the movement of the pickup unit 9 from the distal position to the proximal position, as is the case for example:

- between the situation of Figure 1 and the situation of Figure 2b passing through the situation of Figure 2a;

- between the situation of Figure 2c and the situation of Figure 2d;

- between the situation of Figure 1 and the situation of Figure 3b passing through the situation of Figure 3a.

Thanks to the cam unit 10a and transmission mechanism 10b, the movement system 10 is configured to ensure that each actuation of the transmission mechanism 10b (and rotation of the cam unit 10a, in at least a second angular interval) corresponds with the movement of the pickup unit 9 from the proximal position to the distal position, as is the case for example:

- between the situation of Figure 2b and the situation of Figure 2c;

- between the situation of Figure 2e and the situation of Figure 2f;

- between the situation of Figure 3c and the situation of Figure 3d.

Thanks to the cam unit 10a and transmission mechanism 10b, the movement system 10 is configured to ensure that each actuation of the transmission mechanism 10b (and rotation of the cam unit 10a, in at least a third angular interval) corresponds with the passage of the pickup unit 9 from the release condition to the gripping condition, as is the case for example:

- between the situation of Figure 2a and the situation of Figure 2b;

- between the situation of Figure 3a and the situation of Figure 3b.

Thanks to the cam unit 10a and transmission mechanism 10b, the movement system 10 is configured to ensure that each actuation of the transmission mechanism 10b (and rotation of the cam unit 10a, in at least a fourth angular interval) corresponds with the movement of the pickup unit 9 from the gripping condition to the release condition, as is the case for example, as occurs, for example, between the situation of Figure 1 and the situation of Figure 2a or 3a.

The at least a first angular interval can be superposed at least partly with the at least a third angular interval or with the at least a fourth angular interval, in such a way that the movement of the pickup unit 9 from the distal position to the proximal position can be performed at least partly superposed on the passage of the pickup unit 9 from its release condition to its gripping condition or, respectively, from its gripping condition to its release condition.

The at least a second angular interval can be superposed at least partly with the at least a third angular interval or with the at least a fourth angular interval, in such a way that the movement of the pickup unit 9 from the proximal position to the distal position can be performed at least partly superposed on the passage of the pickup unit 9 from its release condition to its gripping condition or, respectively, from its gripping condition to its release condition.

The above-mentioned angular intervals are to be considered relative to an initial angular reference position of the at least one cam unit 10a relative to a reference system fixed relative to the fixed frame of the machine and relative to an instant of reference referred to the operating step which is performed by the wrapping station 5d at each passage of a bag 4 or 4' in the wrapping station 5d.

In other words, the movement towards and away from the pickup unit 9 to the gripper 3 is controlled by the transmission mechanism 10b (electrical cam), while the condition for gripping or releasing the pickup unit 9 is given by the cam unit 10a.

The control system of the machine 1 (not illustrated) is configured to control the movement system 10 and the other one or more motors and/or actuators of the machine 1 in such a way as to obtain the synchronisation between the following movements and/or operations:

- the rotation of the carousel 2, and therefore the entrance and/or exit of each respective gripper 3 relative to the wrapping station 5d;

- the passage of each respective gripper 3 from its retaining condition to its releasing position and/or vice versa;

- positioning, or otherwise, of the web of overwrapping material N between the proximal position and the distal position of the pickup unit 9;

- the movements of the gripper element 9 from its releasing condition to its gripping condition and/or vice versa;

- the movements of the gripper element 9 from its distal position to its proximal position and/or vice versa.

The control system, by means of the control unit 8 and the at least one sensor 7, is configured to obtain this synchronisation in such a way that the wrapping station 5d performs its operating step, on each respective bag 4 or 4', according to the wrapping mode or according to the rejection mode, depending on whether at least one defect such as to require the rejection has been detected or not in the bag 4 or 4' by the sensor 7.

The control system of the machine 1 is therefore configured so that if the filter bag 4 which is in the wrapping station 5d has been detected as not defective or, in any case, not to the point to be rejected, the wrapping station 5d performs the relative operating step on the bag 4 in accordance with the wrapping mode.

This wrapping mode, in an example embodiment of the machine 1 , comprises the following sub-steps:

- the pickup unit 9 is moved from the position distal to the proximal position, and the gripping unit 9 passes from its release condition to its gripping condition, as shown in Figure 2a;

- the respective gripper 3 passes from its retaining condition to its release position, as shown in Figures 2a and 2b;

- the pickup unit 9 picks up the respective bag 4, as shown in Figure 2b; - the pickup unit 9 moves again towards the distal position, in such a way as to leave the space for the positioning of the web overwrapping material N;

- the unwinding means 6 position the web N between the respective bag 4 retained by the pickup unit 9 and the gripper 3, as shown in Figure 2c;

- the pickup unit 9 is moved again towards the proximal position, in such a way that the respective filter bag 4 intercepts the web N and is wrapped by a portion of the web N which will to make, once separated from the remaining part of the web N, the respective sheet of overwrapping material F, as shown in Figure 2d;

- the respective bag 4 wrapped by the respective sheet F is repositioned in the respective gripper 3 by the gripping element 9;

- the gripper 3 adopts again its retaining condition, the pickup unit 9 adopts again the release condition and moves again towards the distal position, to reach the situation of Figure 2f.

It should be noted that, in an example embodiment of the machine 1 , as shown in Figure 2e, the gripper 3 returns to its retaining condition before the pickup unit releases the respective bag 4 wrapped by the sheet F. It should be noted that in the situation of Figure 2f the pickup unit 9 is in its gripping condition, so that between the situation of Figure 2e and the situation of Figure 2f the pickup unit 9, in the example of operation of the machine 1 shown in the accompanying drawings, has passed from its gripping condition to its releasing condition, and again to its gripping condition.

With reference to this wrapping mode, the unwinding means 6 are configured for positioning a web N of overwrapping material between the proximal and distal positions of the pickup unit 9 and transversally to the movement of the pickup unit 9 from this distal position to the proximal position, as shown in Figure 2c.

In this way, when the pickup unit 9, which is gripping the bag 4, returns from the position distal to the proximal position, the bag 4 intercepts the web N and is wrapped by a portion of the web N. That portion of the web N is cut and separated from the remaining part of the web N preferably simultaneously with the wrapping, thus making the respective sheet of overwrapping material F which wraps the respective bag 4.

The control system of the machine 1 is therefore configured so that if the filter bag 4' which is in the wrapping station 5d has been detected as being defective at least to a point such as to require rejection, the wrapping station 5d performs the relative operating step on the defective bag 4' in accordance with the rejection mode.

This rejection mode, in an example embodiment of the machine 1 , comprises the following sub-steps:

- the pickup unit 9 is moved from the position distal to the proximal position, and the gripping unit 9 passes from its release condition to its gripping condition, as shown in Figure 3a, in order to pick up the bag 4'; - the respective gripper 3 passes from its retaining condition to its release position, as shown in Figures 3a and 3b;

- the pickup unit 9 maintains in position relative to the gripper 3 and/or in the gripper 3 the respective bag 4', as shown in Figure 3b;

- the pickup unit 9 remains in the proximal position and in the gripping condition for at least a period of time during which other operating stations of the machine 1 perform the respective operations on other bags 4 or 4';

- the gripper 3 adopts again its retaining condition, the pickup unit 9 adopts again the release condition and moves again towards the distal position, to reach the situation of Figure 3d.

It should be noted that, in an example embodiment of the machine 1 , as shown in Figure 3c, the gripper 3 returns to its retaining condition before the pickup unit releases the respective bag 4'.

It should be noted that in the situation of Figure 3d the pickup unit 9 is in its gripping condition, so that between the situation of Figure 3c and the situation of Figure 3d the pickup unit 9 has passed from its gripping condition to its releasing condition, and again to its gripping condition. Again with reference to Figure 3b, the control system of the machine 1 is configured so that if the filter bag 4' which is in the wrapping station 5d is defective to the point of requiring rejection, the unwinding means 6 are deactivated, in such a way that it does not cause the escape of the web N, which would interfere with the pickup unit 10 and/or with its movement system 1 1 , whilst the wrapping station 5d operates on the defective bag 4'. In this way, even if the respective gripper 3 passes in any case, even in the case of a defective bag 4', from the retaining condition to the release condition, a suitable control of the movement system 10 means that the defective filter bag 4' is kept in position in the respective gripper 3. Therefore, the control system, in order to perform the operating step of the wrapping station 5d according to the rejection mode, must not vary the control part of the carousel 2 and the grippers 3, but may only vary the control part of the movement system 10 and of the unwinding means 6 of the web of overwrapping material N.

It should be noted, therefore, that if there is a defective bag 4' the control system varies only the control part of the transmission mechanism 10b (electrical cam), so that the wrapping station 5d works or operates according to the rejection mode or according to the wrapping mode.

This structure has the advantage of not modifying the system of mechanical cams present in the station and correlated with the cam units of the carousel and of the other stations.

In Figure 1 the block A denotes, only schematically and generically, the actuating means of the wrapping station 5d. The actuating means comprise, in the case shown in Figure 1 , the motor or actuator which rotates at least one cam unit 10a, the motor of the transmission system 10b, the motor or actuator which determines the feeding of the web N by the unwinding means 6. The block is only shown in order to highlight that the control unit 8 command and/or controls the wrapping station 5d.

According to a second aspect, this invention relates to a method for packaging filter-bags 4 or 4' each wrapped by a sheet or bag of overwrapping material F and containing at least a respective dose of infusion product.

The method comprises the following steps:

- rotating a carousel 2 equipped with a plurality of grippers 3 each designed for adopting a retaining condition and a releasing condition of a respective bag 4 or 4', the rotation causing a movement of each gripper 3 along an operating path in such a way that each respective bag 4 or 4' is transported by the respective gripper 3 along the path;

- a plurality of operating steps carried out sequentially by a plurality of stations 5a to 5g on each respective bag 4 or 4', the stations 5a to 5g being distributed along the operating path;

- detecting at least any one defect in each respective bag 4 or 4', in which the presence of at least one defect can be detected such as to require the rejection of the respective bag 4 or 4';

wherein at least one of the operating steps is performed by a wrapping station 5d and, for each respective bag 4 or 4', it occurs according to a wrapping mode, in accordance with which the bag 4 is picked up by the respective gripper 3, wrapped in a respective sheet of overwrapping material F fed by respective unwinding means 6, and repositioned in the respective gripper 3, or according to a rejection mode, in accordance with which the unwinding means 6 are deactivated and the respective bag 4' is kept in position in the respective gripper 3.

This operating step carried out by the wrapping station 5d is performed according to the wrapping mode if this detecting step does not detect the presence of at least one defect such as to require the rejection of the respective bag, in this case Figures 2a-2f indicate a bag with the numeral 4.

This operating step is carried out by the wrapping station 5d according to the rejecting mode if this detecting step detects the presence of at least one defect such as to require the rejection of the respective bag, in this case Figures 3a to 3d indicate a bag with the numeral 4'. The method preferably comprises a control step in which a control system operates the wrapping station 5d, for each respective bag 4 or 4', according to one of these modes, as a function of the detection.

The control step preferably comprises the following sub-steps:

- at least one detection by means of a sensor 7 which is able to verify at least one defect on each filter bag and generate at least one detection signal U indicating the presence or not of the at least one defect;

- receiving the detection signal U from a control unit 8 designed to send to the wrapping station 5d at least one control signal C to operate the wrapping station 5d according to the wrapping mode, if the detection signal does not indicate the presence of the at least one defect, or according to the rejection mode, if the detection signal indicates the presence of the at least one defect.

The at least one control signal C may comprise, for each detection signal U, a plurality of control signals, for example at least one designed to control the unwinding means 6 and at least one designed to control the movement system 10.

In the embodiment of the machine 1 shown in the drawings, if there are two or more sensors, for example, those labelled 7, 7' or 7", each of them can send at least a respective detection signal U to the control unit 8, representing the presence or absence of at least one defect in a bag 4 or 4' which transits in the respective detection points P, P' and P" associated with the respective sensors 7, 7' and 7'.

The operating step carried out by the wrapping station 5d, according to this rejecting mode, comprises the following sub-steps:

- moving a gripping unit 9 from a distal position to a proximal position with respect to the respective gripper 3 operatively positioned in the wrapping station 5d;

- moving the respective gripper 3 from a condition for retaining the respective bag 4' to a position for releasing the respective bag 4';

- gripping the respective bag 4' by the gripping unit 9 by moving the gripping unit 9 from a releasing position of the respective bag 4' to a gripping condition of the respective bag 4';

- keeping in position the respective bag 4' in the respective gripper 3, or at least with respect to the respective gripper 3, by means of the gripping unit 9;

- moving the respective gripper 3 from a condition for releasing the respective bag 4' to a position for retaining the respective bag 4';

- moving the gripping unit 9 from the gripping condition to the releasing condition to release the respective bag 4' in the respective gripper 3;

- moving the gripping unit 9 from the proximal position to the distal position.

The operating step performed by the wrapping station, according to this wrapping mode, comprises the following sub-steps:

- moving a gripping unit 9 from a distal position to a proximal position with respect to the respective gripper 3 operatively positioned in the wrapping station 5d;

- moving the respective gripper 3 from a condition for retaining the respective bag 4 to a position for releasing the respective bag 4;

- gripping the bag 4 by the gripping unit 9 by moving the gripping unit 9 from a releasing position to a gripping condition of the respective bag 4;

- moving the gripping unit 9, in a gripping position of the respective bag 4, from the proximal position to the distal position;

- positioning a web of a sheet of overwrapping material N between the proximal position and the distal position;

- a movement of the pickup unit 9 from the distal position to the proximal position in such a way that the bag intercepts, whilst it is retained by the pickup unit 9, at least one portion of the web of overwrapping material N;

- positioning the respective bag 4 wrapped by a sheet of overwrapping material F deriving from the portion of the web N in the respective gripper 3;

- moving the respective gripper 3 from a release condition to a condition for retaining the respective bag 4 wrapped in the sheet of overwrapping material F;

- moving the gripping unit 9 from the gripping condition to the releasing condition to release the respective bag 4 in the respective gripper 3.

Summing up, if a defective bag 4' is detected during its formation in the stations upstream of the wrapping station, the control system receives the corresponding signal and prepares the wrapping station for a rejection operating mode condition.

Upon the arrival of the gripper with a defective bag in the wrapping station, the pickup unit moves towards and locks the top of the bag (according to the standard operations) whilst the gripper of the carousel, as per normal operation, opens.

In this situation, the control unit is programmed to prevent both the command for immediate moving away of the pickup unit 9 on the transmission unit 10b (electrical cam) and the command for activation of the means 6 for unwinding the sheet of overwrapping material.

During this step, therefore, the transmission system 10b is programmed to keep the pickup unit 9 in a position proximal to the gripper 3, whilst, as per mechanical phase profile, the cam units 10a keep the pickup unit in the locked position of the defective bag.

Upon completion of the operating steps on the other stations of the machine, the system allows the gripper of the carousel to return to the gripping condition of the defective bag (not wrapped), whilst the pickup unit 9 (thanks to the cam 10a in synchrony with the gripper) releases the defective bag and the transmission unit 10b is enabled to return to the distal position (spaced apart) from the gripper.

Therefore, thanks to this structure of the wrapping station, the machine has these main advantages:

- no modification in the traditional cam systems, including that relative to the opening and closing of the pickup unit, but modifying merely that relative to the movement towards and away from the pickup unit and that relative to the station for feeding the sheet of overwrapping material;

- keeping the defective bag in line on the carousel and locked by the pickup unit (using the working space of the cam unit designed for the opening and closing the pickup unit) until the end of the operating step wherein the gripper retakes the bag; this prevents the risk of dropping the bag from the carousel;

- safety and reliability of operation of the machine thanks to the absence of the sheet of overwrapping material on the defective bag which, in effect, prevents undesired contacts with the operating elements present on the subsequent stations (in particular the sealing units).

As already mentioned, Figure 1 also shows, along the operating path, the outfeed station 5f and the ejection station 5g following the joining station 5e, which can be present in the machine 1 in an example embodiment of it.

In the embodiment shown in Figure 1 , the outfeed station 5f is configured for allowing the outflow of each bag 4 packaged and not defective in such a way that it remains along the production line, for example in such a way that it is transferred towards stations for stacking and packaging in boxes (not illustrated).

In the embodiment shown in Figure 1 , the ejection station 5g is configured for allowing the outflow of each defective bag 4' in such a way that it passes beyond the outfeed station 5f and, therefore, in such a way that it is rejected.

There could, however, be a single outfeed station, for the bags to be rejected and for those not to be rejected, in which case the ejection of the bags to be rejected is performed by means of other components of the machine 1 or of the system in which the machine is installed.

Moreover, in the embodiment shown in Figure 1 , each bag 4 or 4' is subjected, between the wrapping station 5d and the outfeed 5f or ejection 5g stations, to the operating step which is performed by the joining station

5e, which is designed at least to join or close any sheet of overwrapping material F on each non-defective bag 4.