Bag-filling machine and method of packaging in bags with advanced opening of the bag

Abstract

A bag-filling machine (100) comprises a pick-up station (110) and a filling station (120) arranged in sequence along a longitudinal bag advancement line (X). The pick-up station (110) comprises one or more pick-up locations for picking up a bag and the filling station comprises a corresponding number of filling locations for filling a bag. A transporter and opener apparatus (1) is configured to pick up the bags arranged in the pick-up station (110), with a mouth (1a) of each bag closed and parallel to the longitudinal advancement line (X), and to transport them along the advancement line to a respective filling location in the filling station (120). The bag transporter and opener apparatus is also configured to at least partially open the mouth (1a) of each picked-up bag prior to its arrival at the filling station (120), and for this purpose comprises a pair of carriages (10) arranged on opposite sides in a transverse direction (Y-Y) of the longitudinal bag advancement line (X), each carriage (10) being displaceable in a longitudinal direction (X-X) parallel to the advancement line (X) between the pick-up station (110) and the filling station (120). Each carriage (10) also carries respective pressers, designed to cooperate with oppositely arranged pressers of the opposite carriage (10) in order to hold the opposite side edges (1b, 2b) of a bag. Each carriage further carries, for each of said one or more bags (1) in a pick-up location, a respective adhesion group (30), the adhesion groups (30) of the two carriages (10) being arranged opposite each other in the transverse direction and cooperating so as to adhere to the opposite front surfaces (1c) of the bag and to open the mouth (1a) of the bag (1) in the transverse direction. Each filling station comprises a respective pair of grippers (122) for holding the opposite side edges (1) of a bag so as to hold the bag during filling.

Description

[0001] BAG-FILLING MACHINE AND METHOD OF PACKAGING IN BAGS WITH ADVANCED OPENING OF THE BAG

[0002] DESCRIPTION

[0003] The present invention relates to a bag-filing machine and a method of packaging material in bags by means of a bag-filling machine.

[0004] It is known in the product sector relating to the packaging of loose material that there exists the need to arrange said material inside bags which must be filled with a predetermined amount of material and then sealed.

[0005] It is also known that, for this purpose, automatic bag filling machines have been developed, an example of said machines consisting of so-called forming and filling machines which are able to perform at high speed the cycle of forming the bag or picking up a preformed bag, filling the bag and final sealing of the bag mouth.

[0006] In the known machines, the opening of the bag mouth is performed in the filling station when the bag has already arrived underneath the cone supplying the material. This results in a long machine cycle time with consequent reduced productivity of the machine.

[0007] Examples of machines according to the preamble of Claim 1 are described in US2016 / 122057 A1.

[0008] EP 2,925,622 also discloses a bag-filling machine able to obtain opening of the bag mouth before the bag is transferred from a pick-up station to a filling station.

[0009] The associated holding means able to perform said opening are however arranged so as to hold the top rim of the bag along the side folds for the entire duration of the filling cycle, cooperating with the filling cone during opening thereof. The machine described is therefore extremely complex and therefore costly to produce, as well as being complicated to assembly and overall not being able to achieve a real increase in the speed of the machine cycle.

[0010] The technical problem which is posed, therefore, is that of providing a bagfiling machine able to reduce the machine cycle times, while increasing the productivity thereof.

[0011] A particular object of the invention is to provide improved means for opening and transporting a bag from a pick-up station to a filling station.

[0012] In connection with this problem it is also required that said means should be simple to produce and install. A further desirable aspect is that the machine should allow bags of different sizes to be filled, with adjustment of the change in format being managed by programming and control means of the digital type.

[0013] These results are obtained according to the present invention by a bag-filling machine according to the characteristic features of Claim 1 .

[0014] The present invention relates furthermore to a method for the production of bags by means of a bag-filling machine which is able to achieve an increased productivity compared to the known machines.

[0015] Further details may be obtained from the following description of a nonlimiting example of embodiment of the subject of the present invention provided with reference to the attached drawings in which:

[0016] Figure 1a: shows a schematic front view of a bag-filling machine according to the present invention;

[0017] Figure 1b: shows a schematic front view of the filling station of the machine shown in Fig. 1 a, during release of the open bags to the grippers of the filling station by the transporter and opener apparatus;

[0018] Figure 2: shows a schematic top plan view of the station for picking up a bag with small dimensions;

[0019] Figure 3: shows a schematic top plan view of the sequence for holding the bag being handled;

[0020] Figure 4: shows a schematic top plan view of the sequence for opening the bag and simultaneous transport thereof to the filling station;

[0021] Figure 5: shows a schematic top plan view of the sequence for releasing the bag to the filling station;

[0022] Figs.6-9: show schematic views similar to those of Figs. 2-5 for opening a bag with larger width dimensions.

[0023] As shown in Fig. 1 a and assuming, solely for the purposes of description, a set of three reference axes, i.e. a longitudinal axis X-X, parallel to the widthwise dimension of a bag 1 and a line X for advancement thereof between stations of the machine, transverse axis Y-Y, parallel to the direction of opening of the mouth 1 a of a bag and perpendicular to the advancement line X, and vertical axis Z-Z, parallel to a height of the bag 1 , a preferred example of a bag-filling machine 100 (Fig. 1a) according to the present invention comprises: a pick-up station 110 for picking up a bag 1 , a filling station 120 for filling the bag, and a sealing station 130 for sealing the bag mouth, which are arranged in sequence along the longitudinal line for advancement of the bag 1 .

[0024] In the example shown in Fig. 1a, each station 110,120,130 comprises two respective locations, so that the machine 100 is configured to handle simultaneously two bags 1 in each station; the dual-location configuration is that which is preferred in order to achieve an increased productivity while maintaining smaller dimensions and lower overall costs of the machine, but it will be clear to the person skilled in the art that the machine according to the invention may be configured with any desired number of handling locations greater than or equal to one for each station.

[0025] The machine 100 comprises an apparatus for transporting a bag and opening the mouth 1a of a bag, configured to:

[0026] - pick up one or more bags 1 arranged in the pick-up station 110 with the mouth 1a closed and parallel to the longitudinal advancement line X-X; and

[0027] - transport them along the advancement line to a respective filling location in the filling station 120.

[0028] As will become clearer below, the bag transporter apparatus is also configured to open at least partially the mouth 1 a of each picked-up bag, before it arrives at the filling station 120.

[0029] Figure 1a shows the machine 100 with a pair of bags 1 in the pick-up station 110, already picked up and completely opened by the transporter and opener apparatus which is moving the bags towards the filling station 120, and with a pair of bags already filled and closed present in the filling station which has open grippers 122 which have already released the bags 1 and are positioned to receive a following bag 1 to be filled. A pair of bags is also being welded in the sealing station 130.

[0030] Figure 1 b, instead, shows schematically the filling station at the moment of release of the bags 1 , already opened by the transporter and opener apparatus, to the grippers 112 of the filing station 120.

[0031] For simpler description, Figs. 2-9 show a transport and opener apparatus configured to transport and open a single bag 1 , but it is understood that the devices and mechanisms described may be duplicated and / or adapted to handle simultaneously a number of bags 1 corresponding to the number of locations of the filling station.

[0032] In the preferred embodiment shown, the transporter and opener apparatus comprises a pair of carriages 10 arranged on opposite sides (in the transverse direction Y-Y) of the longitudinal bag advancement line and therefore, during use, on opposite sides of the bag 1 in the transverse direction Y-Y.

[0033] Each carriage 10 is displaceable in the longitudinal direction X-X parallel to the advancement line X between the pick-up station 110 and the filling station 120, and vice versa.

[0034] Each carriage 10 preferably comprises a support plate 12 which moves, in particular by means of respective sliding shoes (not shown) sliding on a respective guide rail 11 of a pair of guide rails extending in the longitudinal direction between the said stations, and arranged opposite to each other with respect to the bag advancement line; the carriages 10 may be independent, but move in a coordinated and symmetrical manner along the advancement line.

[0035] Each carriage 10 carries respective presser means 21 designed to cooperate with the presser means 21 of the opposite carriage 10 so as to form a pair of first holding means 20 arranged to hold the opposite side edges 1 b, 2b of a bag.

[0036] Each carriage also carries, for each bag 1 being handled, a respective adhesion group 30, preferably comprising one or more suction cups 30a.

[0037] The two adhesion groups 30 are arranged facing and movable towards and away from each other in the transverse direction Y-Y, perpendicularly with respect to the bag advancement line so as to:

[0038] - grip the bag 1 adhering to the opposite front surfaces 1c thereof following their movement towards each other, and

[0039] - cause opening of the mouth 1a following their movement away from each other in the transverse direction Y-Y.

[0040] In other words, the two adhesion groups 30 of the two carriages 10 cooperate to form second holding means designed to adhere to the opposite front surfaces 1c of the bag and to open the mouth 1a of the bag 1 in the transverse direction.

[0041] In a preferred embodiment, the presser means of each carriage 10 comprise, for each bag being handled, a pair of presser elements, in particular plates 20a, arranged opposite each other in the longitudinal direction X-X and able to be displaced in the longitudinal direction X-X for movement thereof towards each other (Fig. 2) or away from each other (Fig. 5) between a maximum close-together position and a maximum spaced apart position. The presser means can be operated so as to be displaced with respect to the associated carriage towards and away from each other by means of an actuating unit preferably of the electrically actuation type with one or more actuators, also mounted on the plate 12.

[0042] Preferably, the maximum spaced apart position can be correspondingly adjusted to the width size of the bag being handled whose edges 1 b, 2b are to be gripped, between a minimum spaced apart distance (Fig. 3) and a maximum spaced part distance (Fig. 7).

[0043] Moreover, the machine is preferably configured so that, upon variation in the widthwise dimension of the bag being handled, the travel movement of the presser means towards each other between the position spaced from each other and the position close together is fixed and independent of the width of the bag 1 .

[0044] The pressers 20a of each carriage are also movable in a coordinated manner in the transverse direction Y-Y between a position spaced from the advancement line, where they do not interfere with a bag arranged on the said advancement line, and a position close to the advancement line, for gripping the edges 1 b, 2b of a bag arranged on the line X.

[0045] In this way, when each presser 20A of a carriage 10 is in the position close to the advancement line, it forms with the opposite presser 20a of the other carriage 10 a holding gripper arranged so as to grip a respective edge 1b, 2b of the bag 1 which is held between the two pressers 20a.

[0046] As can be seen for example in Fig.1 , the height in the vertical direction Z-Z where the first holding means 20 hold the opposite edges 1b of the bag 1 is, preferably, lower than the upper line (or top rim) of the mouth of the bag 1 by an amount at least such that the grippers 122 of a filling station 120 can be arranged so as to hold the side edges 1b of the bag mouth, above the presser means 20, as will emerge more clearly below.

[0047] In a preferred embodiment, the adhesion group 30 of each carriage is supported on the respective plate and comprises, for each bag 1 picked up along the line, one or more suction cups 30a mounted on a respective transverse arm 31 which can be operated by an actuating unit displaceably in the transverse direction so as to move the one or more suction cups 30a from a position spaced from the advancement line, where there is no interference with a bag arranged on the said advancement line, into a position close to the advancement line, where the suction cups 30a adhere to the respective side surface 1c of the mouth of the bag 1 . As can be seen in Figures 1a-7, the adhesion point is preferably fixed in a substantially central position along the longitudinal width of the mouth of the bag 1 and is preferably at a height in the vertical direction higher than the gripping height of the edges 1b, 2b by the pressers.

[0048] In the preferred machine configuration, the adhesion group 30 is fixed with respect to the carriage in the longitudinal direction X-X, namely the adhesion point of the suction cups 30a does not vary upon variation of the widthwise dimension of the bag being handled.

[0049] The adhesion group 30 may also be associated with suction means (not shown) so that a negative pressure is formed when the bag is gripped, thus ensuring that the bag is stably held during opening of the mouth.

[0050] As shown in figures 4 and 7, from the moment the bag is respectively gripped, the travel movement of the adhesion means 30 in the transverse direction Y-Y and of the presser means 20 in the longitudinal direction X-X is therefore preferably constant and independent of the longitudinal widthwise dimension of the smaller bag 1 (Fig. 4) or larger bag 2 (Fig.7).

[0051] As a result, adjustment of the bag-filling machine may be simplified, irrespective as to the number of bags 1 which are simultaneously being handled along the line (or the number of pick-up and filling locations).

[0052] Said filling station 120, which comprises for each location a filling cone 121 and a pair of grippers 122 for holding the side edges of the top rim of the bag 1 , is arranged downstream of the pick-up station 110 along the advancement line X.

[0053] Each of the grippers 122 of the filling station can be operated so as to close and open in the transverse direction Y-Y in order to hold / release the respective side edge 1b of the mouth 1b of the bag. In the gripper open position, each gripper 122 is advantageously arranged so as not to interfere with the transit of a bag 1 along the advancement line X. In particular, each gripper 122 may comprise a respective pair of jaws 122a, 112b which are movable with respect to each other between a gripper open position and a gripper closed position, the two jaws 122a, 122b being for example hinged together so as to rotate about an axis parallel to the longitudinal direction, between said open position and said closed position of the gripper 122.

[0054] The two grippers 122 of each pair are also movable towards and away from each other in the longitudinal direction X-X parallel to the advancement line X. In greater detail, the two opposite grippers 122 of a pair, which are closed so as to grip the edges of the bag, move between a position close together, corresponding to the width of the open bag 1 arriving at the filling location in order to perform gripping of the edges 1 b, 2b of the bag, and a spaced apart position, which may be adjusted depending on the width of the bag 1 being handled, so as to allow the closing realignment of the mouth 1 a of the bag following filling thereof.

[0055] The close-together position of the grippers 122 in the longitudinal direction X- X may also be adjusted depending on the size of the bag and, for a given bag width, preferably corresponds substantially to the close-together position of the gripping pressers 20a, i.e. to the open condition of the bag mouth.

[0056] According to a preferred configuration, the grippers 122 are arranged open and in the closely arranged position for the arrival, in the filling station, of the bag 1 already opened by the transporter and opener apparatus, close so as to grip the edges of the mouth 1a of the bag, remaining fixed during the filling step, and move to the mutually spaced apart position in the longitudinal direction once filling has been completed, so as to align the mouth 1a of the bag, moving away said side edges held by the jaws 122a, 122b of the grippers 122.

[0057] Preferably, as shown in Fig. 1 b, the grippers 122 in the closed position are arranged at a height in the vertical direction Z-Z such that they take hold of the edge 1b, 2b of the bag mouth above the part of the side edge held by the respective oppositely arranged pressers 20a, so that the bag may be easily released to the filling station and the grippers 122 may be arranged opposite the top rim of the bag so as to cooperate better with the filling cone.

[0058] As shown in Fig. 1a, the sealing station 130, which has a number of sealing locations corresponding to the number of filling and pick-up locations, is preferably arranged downstream of the filling station 120 along the advancement line X. The sealing locations for sealing the mouth of the bag 1 may be conventional and are not described in detail here.

[0059] For the transport of the one or more filled bags 1 with the mouth 1a closed, from the filling station to the sealing station 130, the machine 100 comprises third holding and advancing means 40 configured to hold the closed bag underneath its mouth 1a and transport it from the filling station to the sealing station 130. In greater detail said third holding means 40 preferably comprise a pair of pressure bars arranged opposite each other in the transverse direction on opposite sides of the advancement line X and movable towards and away from each other with respect to the advancement line between a spaced apart position, where there is no interference with the bags 1 arranged on the line, and a close together position for gripping the opposite surfaces 1c of the bag which are held between the pressure bars 40. Each bar 40 has preferably a longitudinal length such as to hold simultaneously all the bags 1 arranged simultaneously in the filling station 120. Alternatively, it is possible to arrange a pair of bars 40 opposite each other for each bag to be transported.

[0060] Optionally, the carriages 10 may extend in the longitudinal direction X-X so as to support the third means 40 for holding and advancing the bags 1 , which, during use, will be arranged downstream of the first holding means 20 and moved by the carriages 10 between the filling station 120 and the sealing station in a manner coordinated with the first holding means 20 and second holding means 30.

[0061] In particular, according to a particularly preferred configuration, each carriage 10 carries one or more bars of the third holding means 40 arranged on the respective side of the advancement line X, so that the third holding means 40 are displaced in the longitudinal direction in a manner coordinated with the displacement of the first holding means 20 and the second holding and opening means 30. This configuration results in a transporter and opener apparatus which is extremely simple to control and speeds up the production cycle. The third holding means 40 could also be mounted on respective second independent carriages which are controlled in a manner coordinated with the carriages 10 in order to synchronize the transport of the empty and full bags 1 between the stations 110, 120, 130.

[0062] In particularly preferred embodiments, the height in the vertical direction for holding of the surfaces of the bag 1 by the pressure bars 40 is situated underneath the gripping height of the grippers 122 of the filling station 120 and the top rim of the bag 1 , thus allowing optimum picking up of the full bag at the filling station 120, with the mouth 1a of the bag 1 which is held by the grippers 122 until the third holding means 40 for advancement of the bag pick it up.

[0063] The preferred machine described may be used in a preferred example of implementation of a method for packaging loose material in bags by means of a bag-filling machine comprising an in-line pick-up station 110 for picking up a bag 1 , a filling station 120 for filling the bag and optionally a sealing station 130 for sealing the bag mouth and an apparatus for transporting and opening the bag 1 , the method comprising the following steps:

[0064] - positioning each carriage 10 in the station 10 for picking up the bag 1 ,2, with the presser means 20a in the position mutually spaced apart in the longitudinal direction X-X and in the position of non-interference in the transverse direction Y-Y, spaced from the advancement line X, and with the adhesion groups 30 spaced from the advancement line X;

[0065] - feeding at least one bag 1 to the pick-up station with the closed mouth arranged parallel to the advancement line X;

[0066] - displacing the presser means 20a of each carriage 10 in the transverse direction Y-Y with holding of the edges 1b, 2b of the bag between the presser means 20a mounted on the first carriage 10 and the oppositely arranged presser means 20a mounted on the other carriage;

[0067] - operating in the transverse direction the adhesion means 30 of each carriage 10 into the position close to the advancement line X, with gripping of the opposite front surfaces 1c, 2c of the bag by the oppositely arranged adhesion means 30 mounted on the carriages 10;

[0068] - displacing the carriage from the station 110 for holding the bag to the station 120 for filling the bag; and

[0069] - simultaneously moving away from each other in the transverse direction the adhesion means 30 holding the surfaces 1c of the bag 1 and moving towards each other the first holding means 20 so as to shorten the width of the mouth 1 a and allow opening thereof in the transverse direction by the adhesion means 30;

[0070] - terminating the travel of the carriage at the filling station with the bag mouth open;

[0071] - closing each of the grippers 122 of the filling station, the grippers of each pair being arranged in a position close together in the longitudinal direction X-X so as to hold the opposite side edges 1b, 2b of the mouth of the respective bag;

[0072] - releasing of the bag by the presser means 20a and the adhesion means 30;

[0073] - return, to the pick-up station, of the first holding means 20 and the second holding means 30 mounted on the carriages 10, for picking up of a new bag 1 ;

[0074] - insertion of the filling cone into the mouth 1a of the open bag and holding by the pair of grippers 122 of the filling station, with filling of the bag with a predefined amount of product;

[0075] - closing and extracting the cone from the bag mouth 1a;

[0076] - operating the grippers (122) of each pair of grippers of the filling station away from each other in the longitudinal direction X-X so as to cause the realignment of the surfaces of the bag mouth 1a and therefore closing thereof.

[0077] In preferred embodiments, the bag opening movements performed by the pressers 20 and the adhesion means 30 may occur entirely in the pick-up station, entirely during the displacement between the pick-up station and the filling station or partially in the pick-up station and partially during the displacement towards the filling station.

[0078] Once filling and closing of the bag mouth have been completed, the bag is held by the third holding means 40 which are operated in the transverse direction Y-Y into the position close to the advancement line X where they are arranged so as to hold the opposite surfaces 1c of the closed bag 1 . The grippers 122 of the filling station may at this point move into the open position, releasing each filled bag 1 which is held by the pressure bars 40 and is transported in the longitudinal direction X-X to the mouth sealing station 130.

[0079] Advantageously, the holding height in the vertical direction of the pressure bars 40 is situated underneath the gripping height of the grippers 122 of the filling station 120 and the top rim of the bag 1 , so that the bag may be kept properly closed and aligned by the grippers 122 until the third holding means pick them up. it is therefore clear how, with the machine according to the invention, it is possible to obtain opening of the bag mouth before the bag reaches a filling station where filling may be immediately started without delay, resulting in a reduction in the overall cycle time of the machine and therefore greater productivity thereof compared to the machines of the prior art.

[0080] In addition, owing to the possibility of maintaining the same constructional form of the presser and adhesion means upon variation in the size and number of the bags to be handled, many components of the apparatus may be standardized, resulting in economies of scale while reducing the manufacturing costs.

[0081] Owing to the particular arrangement with the carriages arranged on opposite sides of the advancement line, carrying respective holding and opening groups cooperating with each other, it is also possible to move the carriages without these interfering with the handling of the bags already present along the line, making use of the periods where the bags are parked awaiting the return of the carriages from / to the respective stations for the next pick-up, opening and transport cycle.

[0082] Owing to the use of electrical actuation systems it is possible to coordinate easily the movements of the carriages and respective presser and adhesion groups between the two opposite sides of the advancement line, reducing the number of mechanical components which are subject to wear.

[0083] Owing to the particular position in which the edges of the bags are held for transport thereof and opening of the mouth, the holding means of a filling station are able to hold the side edges of the bag mouth when it is released by the transport pressers 20; this facilitates the action of the filling cone which is able to open completely, tensioning the bag and preventing material from coming out.

[0084] The use of third holding means for advancement of the bags from the filling station to the sealing station, which move in a manner coordinated with the presser and adhesion means and which are preferably mounted on the same carriages, further optimizes beneficial use of the downtime and simple operation of the machine, to the advantage of the production cycle speed and the overall simplicity.

[0085] The relative arrangement of the holding, adhesion and gripping means of the filling station and optionally of the third holding and advancement means ensures correct holding of the edges of each bag in the desired open or close position along the whole of the travel path along the advancement line and positioning in the respective stations, thereby benefiting optimum opening, closing and sealing without misalignment or loss of material.

[0086] Although described in connection with a number of embodiments and a number of preferred examples of implementation of the invention, it is understood that the scope of protection of the present patent is determined solely by the claims below.

Claims

CLAIMS1. Bag-filling machine (100) comprising a pick-up station (110) and a filling station (120) arranged in sequence along a longitudinal bag advancement line (X), the pick-up station (110) comprising one or more pickup locations for picking up a bag and the filling station comprising a corresponding number of filling locations for filling a bag, the bag-filling machine further comprising a bag (1 ) transporter and opener apparatus configured to pick up the one or more bags arranged in the pick-up station (110), with a mouth (1 a) of each bag closed and parallel to the longitudinal advancement line (X), and to transport the one or more picked-up bags along the advancement line to a respective filling location in the filling station (120); wherein each filling location comprises a respective pair of grippers (122) for holding the opposite sides edges (1 ) of a bag, in order to hold the bag during filling, wherein the bag transporter and opener apparatus is further configured to at least partially open the mouth (1 a) of each picked-up bag prior to its arrival at the filling station (120), characterized in that the bag transporter and opener apparatus comprises a pair of carriages (10) arranged on opposite sides in a transverse direction (Y-Y) of the longitudinal bag advancement line (X), each carriage (10) being displaceable in a longitudinal direction (X-X) parallel to the advancement line (X) between the pick-up station (1 10) and the filling station (120); each carriage (10) carries respective presser means (21 ) designed to cooperate with oppositely arranged presser means (21 ) of the opposite carriage (10) in order to form, for each of said one or more bags (1 ) in a pickup location, a respective pair of first holding means (20) arranged to hold the opposite side edges (1 b, 2b) of a bag; each carriage further carries, for each of said one or more bags (1 ) in a pick-up location, a respective adhesion group (30), the adhesion groups (30) of the two carriages (10) being arranged opposite each other in the transverse direction and cooperating to form second holding means designed to adhere to the opposite front surfaces (1 c) of the bag and to open the mouth (1 a) of the bag (1 ) in the transverse direction during the travel movement between the pick-up station and the filling station.

2. Machine according to Claim 1 , characterized in that the adhesiongroups (30) of the two carriages (10) are movable towards and away from each other in the transverse direction (Y-Y) perpendicularly to the bag advancement line, so as to grip the respective bag (1 ) adhering to the opposite front surfaces (1c) thereof following their movement towards each other, and so as to cause opening of the bag mouth (1 a), following their movement away from each other in the transverse direction (Y-Y).

3. Machine according to one of the preceding claims, wherein the pressers (20a) of each carriage are movable in a coordinated manner in the transverse direction (Y-Y) between a position spaced from the advancement line so as not to interfere with a bag arranged on the said advancement line, and a position close to the advancement line, for gripping the edges (1b, 2b) of a bag arranged on the line (X), such that when each presser (20a) of a carriage (10) is in the position close to the advancement line, it forms with the opposite presser (20a) of the other carriage (10) a holding gripper arranged so to grip a respective edge (1b, 2b) of the bag (1), which is held between the two pressers (20a).

4. Machine according to one of the preceding claims, wherein a height in a vertical direction (Z-Z) where the first holding means (20) hold the opposite edges (1 b) of the bag (1) is lower than an upper line of the mouth of the bag (1 ) by an amount at least such that the grippers (122) of a filling station (120) can be arranged so as to hold the side edges (1b) of the bag mouth, above the presser means (20a).

5. Machine according to one of the preceding claims, wherein the adhesion group (30) of each carriage (10) comprises, for each picked up bag (1) along the line, one or more suction cups (30a) mounted on a respective transverse arm (31 ) which can be operated by an actuating unit for displaceable actuation in the transverse direction so as to move the one or more suction cups (30a) from a position spaced from the advancement line, where there is no interference with a bag (1) arranged on the advancement line, into a position close to the advancement line, where the one or more suction cups (30a) adhere to the respective side surface (1c) of the mouth of the bag (1).

6. Machine according to the preceding claim, wherein the adhesion point of each adhesion group (30) on the mouth of the bag (1 ) is at a height in the vertical direction higher than the height where the edges (1b, 2b) are gripped by the first holding means (20).

7. Machine according to one of the preceding claims, wherein the adhesion group (30) is fixed with respect to the associated carriage (10) in the longitudinal direction (X-X), such that an adhesion point of the adhesion group (30) on the mouth (1 a) of the bag to be picked up does not vary upon variation of the widthwise dimension of the bag in the pick-up location.

8. Machine according to one of the preceding claims, wherein the filling station (120) comprises, for each filling location, a filling cone (121) arranged between the grippers (122) of the filling location along the advancement line.

9. Machine according to one of the preceding claims, wherein each of the grippers (122) of the filling station can be operated so as to close and open in the transverse direction (Y-Y) in order to hold / release the respective side edge (1b) of the bag mouth (1 a), wherein in the gripper open position, each gripper (122) is arranged so as not to interfere with the transit of a bag (1) along the advancement line (X).

10. Machine according to the preceding claim, wherein each gripper (122) of the filling station comprises a respective pair of jaws (122a, 122b) movable with respect to each other between a gripper open position and a gripper closed position, the two jaws (122a, 122b) being hinged with each other so as to rotate about an axis parallel to the longitudinal direction, between said open position and said closed position of the gripper (122).

11. Machine according to one of the preceding claims, wherein the two oppositely arranged grippers (122) of each pair of grippers of the filling station are movable towards and away from each other in the longitudinal direction (X-X) parallel to the advancement line (X), between a position close together, corresponding to the width of the open bag (1) arriving at the filling station in order to perform gripping of the edges (1b, 2b) of the bag, and a spaced apart position, which is adjustable based on the width of the bag (1 ) being handled, for allowing a closing realignment of the bag mouth (1a) following filling thereof.

12. Machine according to the preceding claim, wherein the travel of each gripper in the longitudinal direction (X-X) between the close together position and the spaced apart position of the grippers (122) is fixed upon variation of the widthwise dimension of the bag being handled.

13. Machine according to one of the preceding claims, configured such that the grippers (122) of the filling station are arranged in the open position and in the close together position for the arrival, in the filling station, of thebag (1) already open by the transporter and opener apparatus, are then closed so as to grip the edges of the mouth (1a) of the bag, remaining fixed during the filling step, and move to the spaced apart position in the longitudinal direction once filling has been completed, so as to close the mouth (1 a) of the bag by moving away from each other the side edges held by the jaws (122a, 122b) of the grippers (122).

14. Machine according to one of the preceding claims, wherein a height in the vertical direction (Z-Z) of the grippers (122) in the closed position is such that the grippers take hold of the edge (1 b, 2b) of the bag mouth above a part of the side edge (1 b2b) held by the respective oppositely arranged pressers (20a).

15. Machine according to one of the preceding claims, further comprising a sealing station (130) which has a number of sealing locations corresponding to the number of filling and pick-up locations, the sealing station (130) being arranged downstream of the filling station (120) along the advancement line (X).

16. Machine according to the preceding claim, further comprising third holding means (40) for holding and advancing bags, configured to hold the one or more filled bags with the closed mouth (1a) underneath the respective mouth (1a) and transport them from the filling station to the sealing station (130).

17. Machine according to the preceding claim, wherein said third holding means (40) comprise at least one pair of pressure bars arranged opposite each other in the transverse direction on opposite sides of the advancement line (X) and movable towards and away from each other with respect to the advancement line between a position spaced apart, where they do not interfere with the one or more bags (1 ) arranged in line, and a position arranged close together for gripping the opposite surfaces (1c) of the one or more bags which are held between the pressure bars (40).

18. Machine according to Claim 16 or 17, wherein said third holding means (40) are mounted on said carriages and arranged on opposite sides of the advancement line (X), so that the third holding means (40) are displaced in the longitudinal direction between the filling station (120) and the sealing station in a manner coordinated with the displacement of the first holding means (20) and the second holding and opening means (30).

19. Machine according to one of Claims 17 or 18, wherein a height, in thevertical direction, for gripping of the surfaces of the bag (1) by the third holding means, in particular by said pressure bars (40), is situated below the height for gripping of the edges (1b, 2b) by the grippers (122) of the filling station (120) and the top rim of the bag (1).

20. Method for packaging loose material in bags (1 ) using a bag-filling machine according to one of the preceding claims, the method comprising the following steps:- positioning each carriage (10) in the pick-up station (110) for picking up the bag (1 ,2), with the presser means (20a) in the position mutually spaced apart in the longitudinal direction (X-X) and in a position for non-interference in the transverse direction (Y-Y), spaced from the advancement line (X), and with the adhesion groups (30) spaced from the advancement line (X).- feeding at least one bag (1) to the pick-up station with the closed mouth arranged parallel to the advancement line (X);- displacing the presser means (20a) of each carriage (10) in the transverse direction (Y-Y) with holding of the edges (1b, 2b) of the at least one bag between the presser means (20a) mounted on the first carriage (10) and the oppositely arranged presser means (20a) mounted on the other carriage;- operating in the transverse direction the adhesion group (30) of each carriage (10) into the position close to the advancement line (X), with gripping of the opposite front surfaces (1c, 2c) of the bag by the oppositely arranged adhesion groups (30) mounted on the carriages (10);- simultaneously moving away from each other in the transverse direction the adhesion groups (30) holding the surfaces (1c) of the bag (1) and moving towards each other the first holding means (20) so as to shorten the width of the bag mouth (1 a) and allow opening thereof in the transverse direction by the adhesion groups (30);- displacing the carriage from the bag pick-up station (110) to the bag filling station (120) with positioning of the at least one bag in the filling station with the bag mouth open;- closing each of the grippers (122) of the filling station, the grippers of each pair being arranged in a position close together in the longitudinal direction (X-X) so as to hold the opposite side edges (1 b, 2b) of the open mouth of the respective bag (1);- releasing of the bag by the presser means (20a) and the adhesion groups (30);- return movement to the pick-up station of the first holding means (20) and the second holding means mounted on the carriages (10), for picking up of a new bag (1);- insertion of the filling cone into the mouth (1a) of the open bag held by the pair of grippers (122) of the filling station, with filling of the bag with a predefined quantity of product;- closing and extracting the cone from the bag mouth (1 a);- operating the grippers (122) of each pair of grippers of the filling station away from each other in the longitudinal direction (X-X) so as to cause the realignment of the surfaces of the bag mouth (1a) and therefore closing thereof.

21. Method according to the preceding claim, wherein said simultaneous movement away from each other of the adhesion groups (30) gripping the surfaces of the bag (1) in the transverse direction and movement towards each other of the first holding means (20) in order to shorten the width of the mouth (1a) and allow opening thereof in the transverse direction by the adhesion groups (30) occurs entirely in the pick-up station, or entirely during the displacement between the pick-up station and the filling station, or partially in the pick-up station and partially during displacement.