Installation for packaging liquid doses in sealed bags and use thereof

Abstract

The invention concerns an installation for packaging liquid doses in sealed bags produced from a longitudinally open blown tubing, comprising a vertical frame, means for moving along said blown tubing, a pipe supplying said liquid, means for welding said opening, means for welding the opposite edges of said tubing beneath the end of said pipe and cutting means. A first welding and cutting station is arranged on either side of said pipe, to provide first weld seams and cuts, a second welding and cutting station is arranged beneath the end of said pipe to provide first weld seams and cuts, a second welding and cutting station is arranged beneath the end of said pipe to produce transverse weld seams to link the two adjacent ends of the first weld seams located on either side of said feeding pipe of two adjacent pairs of said first weld seams and to form cut-outs.

Description

[0001] The present invention relates to an installation for packaging doses of liquid in sealed bags produced from a sheath of a heat-sealable flexible material, open longitudinally, comprising a vertical framework comprising means for causing this sheath to pass downward, a feed pipe for said liquid entering said sheath through said longitudinal opening, means for welding said longitudinal opening below the passage for said filling pipe through said longitudinal opening, transverse welding means for connecting the opposite longitudinal edges of said sheath under the dispensing end of said feed pipe, and cutting means for separating the bags containing said doses, and to the use of this installation.

[0002] A bag of this type, also comprising a valve adjacent to a pouch containing a straw one end of which is engaged in the entry to the valve, its method of manufacture and of packaging are described in EP-0 948 446. As far as the actual packaging is concerned, this document does, however, provide relatively little detail and does not disclose the means used for this purpose. Nor does it disclose any solution for continuous packaging. As described, the shape of the bags is given by the edges of the material in web form and by transverse welds, connecting the two longitudinal edges of the web-form material, giving the bag a quadrilateral profile.

[0003] The method that consists in continuous vertical packaging of bags, single-serving cartons or parallelepipedal bricks from a continuous tubular material, is well known. However, vertical packaging installations used for this purpose permit the production only of volumes of quadrangular profiles or volumes with regulated surfaces, dictated by the tubular shape of the sheath from which they are made, leaving little or no place for the imagination and not allowing the bags thus produced to be given a novel or even playful nature. In addition, a given installation can produce only bags of identical shapes and sizes. Only the decoration and/or the captions borne on the external surface of the bag allow the bag to be customized to the product it contains and/or the brand name of the manufacturer of the product packaged in this bag.

[0004] The main object of the present invention is to allow the continuous packaging of liquid, advantageously, although not exclusively, into bag blanks as described in the aforementioned document, and the formation of bags capable of exhibiting various shapes easily modified to suit the requirements or shape that is to be given to the bag with a minimum amount of work.

[0005] To this end, the subject of the present invention is first of all an installation for packaging doses of liquid in sealed bags produced from a sheath of a heat-sealable flexible material, as claimed in claim 1. Another subject of this invention is then the use of this installation as claimed in claim 10.

[0006] One of the advantages of this installation is that the bag is given most of the shape of its periphery before it is filled, leaving between the two welded parts on each side of the filling pipe only a passage for this pipe, so that the liquid is practically already confined within the periphery of the bag. This welding that gives most of the shape to the bag is accompanied by the cutting operation for separating the welded portions from the sheath from which the bag is formed. By virtue of this design, it becomes possible to vary the shape of the periphery given to the bag, because this is no longer dictated by the straight edges of the tubular sheath.

[0007] In consequence, all that is required is a change of welding and cutting tools and the profile given to the bag can be changed. Combining a given profile with appropriate printing of the profile makes it possible to give the bag particular appearances. Thus, for example, the profile may be reminiscent of that of a fruit, the printing on the bag then reproducing that of the skin of the fruit. Such a bag can then be used to package the juice of the fruit in whose likeness the bag is produced. This appearance is obviously not restricted to the aforementioned example; it may adopt that of imaginary or real people, caricatures, objects connected with sports events, animals, etc. The profile given to the bag may also be chosen to evoke a topic used in the context of an advertising campaign.

[0008] Advantageously, when the packaging installation is used to fill bags the blanks of which are produced in accordance with EP-0 948 446 as mentioned above, the workstations of the installation relating to the packaging of the actual liquid are preceded by a station intended to open the end wall of a pouch adjacent to the passage in the valve and to place a straw in this passage and in the adjacent pouch.

[0009] Other features and advantages of the present invention will become apparent from reading the description which follows, given in relation to the attached drawings which, schematically and by way of example, depict one particular embodiment of the installation that is the subject of the present invention and its use.

[0010] FIG. 1 is an elevation of this embodiment;

[0011] FIG. 2 is an enlarged part view of FIG. 1, illustrating the first welding and cutting station;

[0012] FIG. 3 is a view on III-III of FIG. 2, with the welding and cutting tool removed;

[0013] FIG. 4 is a part view of the welding and cutting tool alone, viewed on IV-IV of FIG. 2;

[0014] FIG. 5 is a view on V-V of the FIG. 1, illustrating the second welding and cutting station;

[0015] FIG. 6 is a perspective view of the welding and cutting tools alone, that are intended to be associated with the second welding and cutting station of FIG. 5;

[0016] FIG. 7 is an enlarged part view of FIG. 1;

[0017] FIG. 8 is a section on VIII-VIII of FIG. 7;

[0018] FIG. 9 is an enlarged part view of a detail of FIG. 8;

[0019] FIG. 10 is a diagram of the series of operations of the second welding and cutting station.

[0020] The installation illustrated in FIG. 1 comprises a framework B comprising two parts B1 and B2 side by side. The part B1 is intended to form straws P and feed them into bags the blanks of which, in this example, are already formed from a web-form material in the form of a flattened sheath G. This sheath G is stored in the form of a reel (not depicted) and conveyed to the part B2 of the framework B by a roller 1, arranged at the top of this part B2 which more especially forms the subject of the present invention.

[0021] This sheath G is longitudinally open along its left-hand edge with reference to FIG. 1. In this example, as it travels down, this sheath G passes through a straw-loading station 2. This station is obviously needed only if straws P have to be loaded into the bags formed in the sheath G and more particularly when these bags are fitted with valves. The sheath G then passes through a first welding and cutting station 3 and through a second welding and cutting station 4.

[0022] The first welding and cutting station 3 is depicted in greater detail in FIGS. 2 to 4 and comprises a support frame 5 connected to the framework B2 by two runners 6 mounted on two vertical slides 7 secured at each of their ends to two parallel fixing plates 8 fixed to the framework B2 by bolts 9. Wing nuts 10 are used to fix the runners 6 onto the vertical slides 7. An adjusting handwheel VR is secured to a shaft 70 the end of which is engaged with a screw jack 71 intended to move the support frame 5 vertically on the vertical slides 7. This adjustment is intended to alter the position of the welding and cutting station to suit the size of the bags in which the liquid is packaged.

[0023] Two tool supports 11 and 12 are each mounted to slide on one of two slides 13 and 14 respectively, that are fixed to two parallel sides of the support frame 5. Each of these supports 11, 12 is connected to an actuator 15 and 16 respectively, to cause these supports to slide on the slides 13, 14. Each tool support 11, 12 comprises two tool holders 17, 18 and 19, 20, respectively. Each tool holder 17-20 has a fixing dowel 21, 22, 23, or 24, respectively, each of which dowels passes through supports 25, 26, 27 and 28 respectively, exhibiting the form of pairs of parallel plates, pierced with coaxial openings. At one of their ends, the fixing dowels 21-24 end in heads 21a, 22a, 23a and 24a, respectively, while keys 21b, 22b, 23b and 24b respectively, retain them at their other ends.

[0024] The two tool holders 17, 18 and 19, 20, respectively, of the tool supports 11, 12 are each mounted to slide on two respective slides 29a, 29b and 30a, 30b. Wing nuts 17a, 18a, 17b, 18b, 19a and 20a, respectively, two other nuts symmetric with the last two 19a, 20a not being visible, are used to clamp the tool holders 17-20 on the slides 29a, 29b, 30a, 30b. Two adjusting knobs 31, 32 (FIG. 2) are secured to spindles of which a threaded part is engaged with a nut (not depicted) secured to each of the supports 17, 18 respectively. These adjusting knobs 31, 32 are used to move the supports relative to the slides 29a, 29b.

[0025] FIGS. 2 and 4 show in greater detail three of the four tools, the fourth not being visible, 33, 34 and 35 mounted on the four tool holders 17-20. Each tool 33-35 comprises on its rear face a fixing block, of which just two, 36, 37, are visible in FIG. 4. Each block has, passing through it, a bore 36a, 37a intended for the passage of a fixing dowel 21, 23, respectively, the other two bores not being visible.

[0026] Each tool 33, 34 comprises, in its upper part, a welding electrode 38, 39 that can be seen in broken line in FIG. 2. The flat surfaces of the tool 35 and of the non-visible tool facing the tool 34, are situated opposite electrodes 38, 39, respectively, and constitute opposite electrodes. The welds made by the two electrodes 38, 39 define the entire periphery of the bag except for a vertical passage 40 (FIG. 2) formed between the tools 33, 34 on the one hand, and between the tool 35 and the non-visible tool situated facing the tool 34 (FIG. 2). The vertical passage 40 is intended to allow a liquid feed pipe 41 to pass (FIG. 1).

[0027] The lower parts of the two tools 33, 34 (FIGS. 2 and 4) each comprise a moving cutter 42, 43 actuated by an actuator 44, 45. These moving cutters 42, 43 have a shape corresponding to the external edge of the welding electrodes 38, 39. The two tools, of which just the tool 35 is visible, comprise, facing each moving cutter 42, 43, a receiving groove of which only the groove 46 is visible in FIG. 4, of a shape corresponding to that of the moving cutter 42.

[0028] The actuating mechanism of the second welding and cutting station 4 is illustrated in greater detail by FIG. 5, while the tools intended to be associated with this actuating mechanism are illustrated in FIG. 6. The entirety of this actuating mechanism is carried by a horizontal rectangular chassis 47 secured to two vertical slides 48, 49, each engaged with a linear motor 50, 51, each of which is fixed to the framework B2 (FIG. 1) by fixing brackets 52.

[0029] The two short sides of the rectangular chassis 47 each bear an actuator 53, 54, each of these being in engagement with a slide 55 and 56 respectively, mounted on the chassis via guide rails (not depicted) running along the two sides 47a, 47b of the chassis 47. The slide 55 bears a runner 57 able to be moved at right angles to the slide 55 by drive motors M1, M2, that is to say transversely to the chassis 47. The slide 56 also bears a runner 58 that can also be moved transversely to the chassis, by drive motors M3, M4.

[0030] Each runner 57, 58 carries two tool holders 59, 60 and 61, 62, respectively, each of these being secured to an actuator 63, 64 and 65, 66, respectively. A free roller 67, arranged transversely at the center of the chassis 47 is intended to take the bottom of the sheath G.

[0031] The tools intended to be mounted on the second welding and cutting station 4 are illustrated in perspective in FIG. 6. These tools comprise a welding electrode 68 situated facing an opposite electrode 69, these two members 68, 69 being fixed to the supports 60, 62 by fixing pieces 100. Advantageously, the opposite electrode 69 is associated with cooling means. The two other supports 59, 61 bear the cutting members 72, 73. Whilst the member 73 is a fixed cutting anvil member connected to the support 59 by fixing pieces 100, the cutting member 72 is formed of a block mounted to slide on fixing rods 101 and pressed toward the cutting anvil member 73 by return springs 102. This set-up allows the block to retreat when it meets the cutting anvil member 73 and thus to allow the cutters (not visible) to deploy.

[0032] The welding members 68, 69 and cutting members 72, 73 are shaped to simultaneously close then cut lower and upper parts of two adjacent bags, in order to connect, through the space 40 left free, the welds made at the first welding and cutting station 3 by the electrodes 38 and 39, thus forming a continuous weld delimiting a packaging volume for the liquid.

[0033] Two pairs of gripping lips 74, 75; 76, 77 are arranged respectively above and below these welding 68, 69 and cutting 72, 73 tools and are intended to be fixed to the slides 55 and 56 respectively. The lips 74 and 76 advantageously exhibit an attached tongue 74a, 76a, made of an elastically compressible material such as an elastomeric material used for producing seals. These lips serve to grip the sheath G during the welding and cutting operations. Given that, as will be explained in the course of the description relating to the operation, the workstation is moved downward by the linear motors 50, 51 during the welding and cutting operations, the gripping lips 74-77 also serve to pull the sheath G without slippage during these welding and cutting operations.

[0034] According to a preferred embodiment of the present invention, the bags formed by the welding and cutting units 3, 4 comprise a valve, for example, like the bag described in EP-0 948 446.

[0035] The packaging installation according to the present invention comprises, upstream of the welding and cutting stations 3, 4, a station 2 for loading the straws P into the passages formed by the valves formed in the sheath G. This station will now be described with reference in particular to FIGS. 7 and 8.

[0036] A transfer disk 78 is mounted to pivot about a horizontal spindle perpendicular to the plane of the sheath G. For this, the center 78a of the disk 78 is fixed and the disk 78 is fixed to a drive means 78b mounted to pivot using ball bearings 79. A gearwheel 78c secured to the hub 78b is connected to a gearwheel 80a of a drive motor 80 by a toothed belt 81. The surface of the disk bears twelve radial slides 82, mounted to slide in supports 82a. Each radial slide 82 is pushed toward the center of the transfer disk 78 by return springs 83 and each of them bears a pusher 84. Radial housings 82b are mounted in the radial slides 82, to accommodate the straws P.

[0037] One radial slide 82 in two carries a folded straw P in an insertion position. Advantageously, these straws are already shaped as described in WO 99/3791. The pushers 84 of the other radial slides 82 situated between those that bear the straws P are configured as puncturing members. What actually happens is that the valves V described in EP 0 948 446 mentioned above occupy the right-hand part of the sheath G (FIG. 7) and their entry is closed by a diaphragm that the pushers 84 configured as puncturing members are intended to perforate in order to give access to the passage in the valve V.

[0038] FIG. 9 shows the device for guiding and clamping the various layers of films that form the sheath in which the valves V are formed. In fact, there are two guiding and clamping devices 85, 86, one situated above and the other below the line of perforation and insertion of straws P, which line consists of a horizontal line passing through the center of the transfer disk 78.

[0039] Each guiding and clamping device 85, 86 has two fixed support surfaces 87, 88 arranged in the shape of a V and between which the edge of the transfer disk 78 passes together with the ends of the slides 82, 82a. These support surfaces 87, 88 are fixed to a part of the framework B2. Clamping surfaces 89, 90, 91 are secured, one of them, 89, to an actuator 92, and the others, 90, 91 to an actuator 93. Two other actuators associated with similar clamping surfaces, and of which only the actuator 93a is visible in FIG. 7, operate in an identical way and serve the same goal as the actuators 92, 93. They are arranged symmetrically above the valve V and thus allow the layers of film of the sheath G to be clamped above this valve V. A film intended to form the outer wall of the bags and a film intended to form the diaphragm sealing a pouch for containing the bent part of the straw P are arranged between the support surface 87 and the clamping surface 89. The film forming the other wall of the bag and a first film for forming the valve V are clamped between the two clamping surfaces 90, 91, while the second film of the valve is clamped between the clamping surface 91 and the bearing surface 88. Ball and spring spacer devices 94, 95 are intended to separate the two clamping surfaces 90, 91 when the actuator 93 is in the open position.

[0040] The fixed center 78a of the transfer disk 78 bears an actuator 96 aligned with the horizontal line of perforation and insertion of straws P passing through the center of this transfer disk 78 and through the passage in the valve V, aligned with the diameter of this transfer disk 78.

[0041] A feed station 97 feeding the transfer disk 78 with straws P lies diametrically opposite the loading station 2 where straws P are loaded into the passages in the valves V. This station comprises fiber-optic positioning means 98 for ensuring precise angular alignment of the transfer disk 78. A pusher 99 is mounted to slide along an axis passing through the center of the transfer disk 78. The front part of this pusher 99 has a smaller diameter than the rear part, so as to be able to enter the bore of the straw P to keep the straw aligned by pushing it into a housing 82b secured to the transfer disk 78.

[0042] The way in which the packaging installation works will now be explained with reference to FIGS. 10 and 11 which give the timing sequence for the operations relating to the first and second welding and cutting stations 4. Given that the operations relating to the straw loading station 2 are performed on the sheath G while it is stationary, as are those at the first welding and cutting station, whereas the second welding and cutting station 4 is also used to advance the sheath step by step and therefore makes a reciprocating vertical movement at the same time as the welding and cutting operations, the operations of the straw loading station 2 and of the first welding and cutting station 3 are performed between the operations of the second welding and cutting station 4.

[0043] It must first of all be emphasized that the liquid feed pipe 41 extends down as far as a level mid-way up the height of the cutting tools 42, 43 (FIGS. 1, 2 and 4), that is to say a level situated appreciably below the first welding station, thus allowing liquid to be fed in at a continuous and constant flow rate without the liquid overflowing.

[0044] While the sheath G is stationary, the straw loading station 2 first of all performs the operation of puncturing the film that seals the entry to the valve V. For this, the actuators 92, 93 clamp the bearing and clamping surfaces 87-91 against each other, immobilizing the sheath G. The actuator 96 placed at the center of the transfer disk 78 is actuated and pushes the slide 82 secured to a perforator 84 toward the sheath G to make through the latter an opening allowing access to the passage of the valve V. The actuator 96 retreats and the slide 82 is moved back by the return springs 83.

[0045] Next, the motor 80 causes the transfer disk 78 to rotate through 30°, corresponding to one angular spacing separating two adjacent slides 82, in order to position a slide 82 into which a straw P has been loaded. The actuator 96 is then actuated once again to engage the front end of the straw P in the passage in the valve V. The depth to which the straw P is engaged in the valve V is chosen so that the valve remains closed. The actuator 96 returns to its initial position and the springs 83 return the slide 82 back, while the straw P remains engaged in the passage in the valve V.

[0046] The operations of puncturing and of loading the straw P which have just been described are performed at the same time as the welding and cutting operations at the first welding and cutting station 3. The sequence of events is illustrated in FIG. 10. The actuators 15 and 16 press the tools 33, 34 and the tools facing them and of which just the tool 35 is visible in FIGS. 2 and 4, against each other. The welding electrodes 38, 39 are then powered with pulses of current to perform the welding of the sheath G. Next, the actuator 44 is actuated to cause the cutters 42, 43 to enter the receiving grooves facing them and of which just the groove 46 is visible in FIG. 4, thus cutting the sheath G on the outside of the welds formed by the electrodes 38, 39, and thus separating them from the remainder of the sheath G.

[0047] As can be seen in FIG. 1, the welding electrodes 38, 39 and the cutters 42, 43 lie at two different levels, which means that the welding and cutting operations performed almost simultaneously by the welding and cutting station are performed on two different bags following on from one another along the sheath G. In this way, one bag is welded while the one just below it is being filled with liquid and at the same time cut. During the next operation cycle, the bag that was welded is lowered by one spacing and therefore finds itself facing the cutters 42, 43.

[0048] The sequence of events in the welding and cutting operations at the second welding and cutting station 4 is illustrated in FIG. 11, referring more especially to FIGS. 5 and 6. First of all, after the end of the operations performed at the first welding and cutting station 3, the actuators 53, 54 drive the tools 72-77 against each other, so that the sheath G is trapped between the lips 74, 75 on the one hand and between the lips 76, 77 on the other, these two lines of gripping lying respectively one above and one below the welding 68, 69 and cutting 73, 74 tools. During the operations that will follow, all of the members mounted on the chassis 47 will be driven downward by the linear motors 50, 51.

[0049] The length of the downward travel will correspond precisely to the length separating two successive bags or to the length separating two successive valves V, which amounts to the same thing. However, whereas the valves V are formed on the sheath G at regular and precise spacings before the operation of packaging liquid into the bags, the bags are not formed until during the packaging operation, at the same time as this, which means that it is the valves V which serve as marker means.

[0050] Next, the actuators 64, 66 controlling the welding tools 68, 69 corresponding to the electrode and to the opposite welding electrode press these tools against each other. The electrodes are powered with current in pulses, making it possible to limit the welding time, then to immediately cool afterwards in an extremely short space of time, it being possible for the opposite electrode 69 to serve as a cooling member by being connected to means (not depicted) for example a bimetal with Peltier effect, to quickly lower its temperature, while at the same time keeping the welded parts clamped together, something that cannot be achieved with resistive heating. The cooling following the welding keeping the parts clamped together is important in this case. This is because at the time of this welding, the bag is full of liquid and has therefore been deformed, which means that the welded surface would crumple. By keeping it clamped as it cools, the appearance of this welded portion is markedly improved.

[0051] Next, the actuators 64, 66 are opened and it is the turn of the runners 57, 58 to be moved by the drive motors M1, M2, M3, M4 in order to bring the cutting tools 72, 73 into the place of the welding tools, that is to say by moving the runners 57, 58 to the right with respect to FIG. 5. After this movement, it is the actuators 59 and 60 that move the cutting tools 72, 73 closer together, causing the cutters of the tool 73 to protrude in order to cause them to enter the grooves in the cutting anvil tool 73, cutting as it passes the portion of sheath G corresponding to the portions welded before. It can be seen from FIG. 6 that the welded portions and the cut portions are used to connect together the two portions already welded by the electrodes 38, 39 (FIG. 2) and cut by the cutters 42, 43, on each side of the space 40 left free to allow the passage of the liquid feed pipe 41. However, whereas the first welding and cutting station 3 performs the welding and cutting operations on two successive bags respectively, the second welding and cutting station 4 performs welding then cutting of two lower and upper parts respectively of two successive bags simultaneously. At the same time, the lower bag, the upper part of which has been welded, is separated from the sheath G after the cutting operation.

[0052] Once cutting is over, the actuators 59, 60 are returned backward, and then it is the turn of the actuators 53, 54 to be returned backward. At the same time, at the end of this welding and cutting operation of the second welding and cutting station 4, the sheath G is lowered by a spacing corresponding to the height of a bag, so that the first welding and cutting station 3 can recommence its operating cycle.

[0053] While the first welding and cutting station 3 is performing its operations, the chassis 47 of the second welding and cutting station 4 is returned upward by one spacing by the linear motors 50, 51.

[0054] It is also during this space of time that the operations of puncturing and loading the straw 2 which we shall now describe are performed, it being understood that these operations are also performed on a stationary sheath. Once the sheath G has been moved by the second welding and cutting station 4, a valve V finds itself aligned in the continuation of the diameter of the transfer disk 78. A slide 82 bearing a perforator 84 is positioned in the diameter of the transfer disk 78 aligned with the passage of the valve V. The four actuators 92, 93, 93a (the actuator 92a not being visible) push the bearing surfaces 89, 90 against each other and against the fixed support surfaces 87, 88 on each side of the valve V. The intermediate bearing surface 91 is clamped between the bearing surface 90 and the support surface 88. The various layers of film forming the sheath G are thus held firmly on each side of the valve V.

[0055] The actuator 96 pushes the radial slide 82 toward the valve V so that the perforator 84 perforates the film that was closing the entry to the passage in the valve V. It will be recalled that, in this example, the sheath G and the valve V are assumed to have been configured as described in EP-0 948 446 to which reference may be made. However, the invention may also obviously be applied to other types of bags equipped with valves. When the actuator 96 retreats, the return springs 83 return the slide 82 backward, with the perforator 84.

[0056] The motor 80 then drives the transfer disk through one spacing, in this example this spacing corresponding to 30°, thus placing the next slide 82 bearing a straw P on the line connecting the center of the transfer disk 78 to the passage in the valve V. The actuator 96 is once again actuated to push the slide 82 and engage the straw P in the passage in the valve V. Once the engagement of the straw P is over, the four actuators 92, 93, 93a (actuator 92a not being visible) retreat, releasing the layers of film of the sheath G.

[0057] At the same time as the operation of loading a straw P into the passage in the valve, the pusher 99 diametrically opposite the valve V with respect to the transfer disk is also actuated to push a straw P into the diametrically opposite slide 82.

[0058] As this operation of puncturing and of loading the straw P are performed at the same time as the operation of the first welding and cutting station 3, a further cycle of the second welding and cutting station 4 with the pulling of the sheath G can restart.

Claims

1. An installation for packaging doses of liquid in sealed bags produced from a sheath (G) of a heat-sealable flexible material, open longitudinally, comprising a vertical framework (B) comprising means (50, 51, 74-77) for causing this sheath (G) to pass downward, a feed pipe (41) for said liquid entering said sheath (G) through said longitudinal opening, means (38, 39) for welding said longitudinal opening below the passage for said feed pipe (41) through said longitudinal opening, transverse welding means (68) for connecting the opposite longitudinal edges of said sheath (G) under the dispensing end of said feed pipe (41), and cutting means (42, 43, 72, 73) for separating the bags containing said doses from said sheath, characterized in that this installation comprises a first welding and cutting station (3), arranged on each side of said feed pipe (41) to form first welds and cuts on the outside of these first welds, a second welding and cutting station (4) below the end of said feed pipe (41) for forming transverse welds for connecting the two adjacent ends of the first welds situated on each side of said feed pipe of two adjacent pairs of said first welds and to form cuts on the outside of said transverse welds.

2. The installation as claimed in claim 1, characterized in that said first and second welding and cutting stations (3, 4) each comprise at least two supports (11, 12; 59-62) arranged on each side of said sheath (G), means (13, 14; 47a, 47b) of guiding these supports (11, 12; 59-62) in a direction transverse to the movement of said sheath (G), actuating means (15, 16; 53, 54) for moving said supports (11, 12; 5962) along their respective guide means, in opposite directions to one another, to move them closer together or further apart, welding means (38, 39, 68, 69), cutting means (42, 43, 72, 73) and fixing means (21-24, 36, 100, 101) for connecting said welding (38, 39, 68, 69) and cutting (42, 43, 72, 73) means removably to said respective supports (11, 12; 59-62).

3. The installation as claimed in one of the preceding claims, characterized in that the supports (59, 60) of the cutting and welding means (69, 73) of said second welding and cutting station (4) situated on one side of said sheath (G) and the supports (61, 62) of the cutting and welding means (68, 72) of this same welding and cutting station (4) situated on the other side of said sheath (G) are each secured to an independent actuating member (63-66) for moving the supports (59, 60) arranged on one side of said sheath (G) and those (61, 62) arranged on the other side of this sheath (G) against each other and for parting them, and in that two sliding devices (57, 58) can be moved in two horizontal and mutually parallel paths, each of them being dynamically connected to two of said supports (59, 60, 61, 62) situated on the same side of said sheath (G), and are engaged with drive means (M1-M4) for causing them to slide along said paths, in two opposite directions alternately, so as to alternately place said welding and cutting means respectively, in a determined working position with respect to said sheath (G).

4. The installation as claimed in claim 3, characterized in that each of the two sliding devices (57, 58) dynamically connected to said respective supports (59-62) arranged on each side of said sheath (G), are secured to two respective sliding members (55, 56) mounted on guide means (47a, 47b) defining a horizontal path perpendicular to the paths of said sliding devices (57, 58), said sliding members each being engaged with drive means (53, 54) for alternately bringing them closer together or moving them further apart, means (74-77) for gripping said sheath (G) being secured to said sliding members (55, 56), the means (47a, 47b) for guiding these sliding members (55, 56) being secured to a chassis (47) engaged with vertical guidance and drive means (50, 51) to drive said chassis alternately downward and upward, the length of this travel being determined according to the vertical dimension of said sealed bags.

5. The installation as claimed in claim 3, characterized in that the vertical position of the welding (38, 39) and cutting (42, 43) means of said first welding and cutting station is fixed during the packaging process, these welding (38, 39) and cutting (42, 43) means being vertically aligned on each side of said sheath (G) with a spacing corresponding to the spacing between two successive ones of said sealed bags.

6. The installation as claimed in claim 5, characterized in that said welding (38, 39) and cutting (42, 43) means are secured to a common support (5) connected to said framework (B2) by height-adjustment means (7, 70, 71, VR) and means (10) of locking these adjusting means.

7. The installation as claimed in one of the preceding claims, characterized in that said welding means (38, 39, 68) consist of pulsed electrical heating means.

8. The installation as claimed in one of the preceding claims, characterized in that said welding means (68) comprise a mating support (69) associated with cooling means.

9. An installation for packaging doses of liquid in sealed bags comprising a valve (V) formed by a passage formed between two thermoplastic films arranged inside said sheath at the location of each of said bags, running transversely to said sheath, and a pouch the end wall of which is adjacent to the entry to said passage of the valve (V) as claimed in one of the preceding claims, characterized in that it comprises, upstream of said first welding and cutting station (3), a station (2) for introducing one end of a straw (P) into said passage in the valve (V), this station (2) comprising means (84) for piercing the end wall of said pouch adjacent to the entry to said passage in the valve (V) and means (82) for inserting one end of a straw (P) into the entry of said passage in the valve (V) and the remainder of said straw (P) into said pouch.

10. The installation as claimed in claim 9, characterized in that said station (2) for introducing a straw (P) into said passage in the valve (V) comprises means (87-93) for flattening and clamping said sheath (G) on each side of said passage in the valve (V), a transfer disk (78) mounted to pivot and roughly coplanar with said flattened sheath (G), a multitude of radial housings (82b) for said straws (P), distributed at uniform angles over this transfer disk (78), an equivalent series of radial guide means (82) for said means (84) for piercing the end walls of said pouches, alternating with said housings (82b), means (80, 81) for moving said transfer disk (78) step by step in order in succession to bring a piercing member (84) and one of said radial housings (82b) into alignment with each of said passages in valves (V), and means (96) for moving said piercing member (84) and said straw (P) radially and alternately toward the outside of the transfer disk (78) when these items are respectively aligned with said passage in the valve (V).

11. The use of the installation as claimed in one of the preceding claims for the packaging, by continuous filling, of said sheath (G) with said liquid at the same time as performing the steps of welding and cutting the periphery of said bags.