FLEXIBLE PACKAGING CONVEYOR BAR DRIVING DEVICE AND HORI ZONTAL PACKING MACHINES AND CONVEYOR EQUIPPED WITH SAID DEVICE

Technical field of the invention

The invention relates to a flexible packaging conveyor bar driving device in horizontal packing machines, of the kind used to hold and transport the packages between two workstations of a machine. The invention also relates to a conveyor belt that includes said driving device and to a horizontal packing machine that includes said conveyor.

Background of the invention

Horizontal packing machines are usually equipped with a package forming module and packing module, which cooperate in such a way that the packages produced by the forming module are transferred individually or in batches to the packing module where, amongst other processes, the packages are filled and sealed.

The packing module comprises of a series of workstations aligned lengthwise wherein said package filling and sealing operations are carried out simultaneously. To this effect, the packages are aligned lengthwise, separated from each other in correspondence with the distance separating the workstations, forming a packing line that advances intermittently, thereby carrying the packages from one station to the next. To this end, the machines are equipped with a conveyor that simultaneously holds all the packages of the packing line and also transports them simultaneously between two consecutive stations.

A conventional conveyor consists of two conveyor bars parallel to the packing line, disposed one on either side, which simultaneously execute longitudinal forward and backward movements alternated with transverse forward and backward movements between them. As the conveyor bars close together, the packages on the packing line are held in place due to the pressure exerted by one bar against the other and carried to the next station as both bars advance simultaneously. Once the packages are transported to the next station, the two bars separate and simultaneously release all of the packages, after which both bars return to their original position in such a way that, when they close together again, the bars hold in

place the packages that comprise the packing line in order to carry them to the next station.

Another type of conveyor is that consisting of a single conveyor bar equipped with a series of pincers specially adapted to hold the packages of the packing line. This bar successively executes a first longitudinal forward movement, during which the packages held between two stations move along; a second transverse movement that crosses the direction of package flow moving away from said packages; a third longitudinal backward movement under vacuum in the direction opposite to package flow; and a fourth transverse movement that crosses the direction of package flow moving towards said packages. Obviously, between the first and second movements the conveyor bar pincers open releasing the packages, while between the fourth and first movement of two consecutive transport cycles the pincers close in order to hold the packages to be transported.

At present, the longitudinal forward/backward and transverse forward/backward movements of the previously described conveyor bars are driven by different devices that move the bars alternately: a first transverse driving device, consisting of one or several support arms for each of the conveyor bars, which are driven simultaneously in order to approach and withdraw from the packing line and move the bar or bars transversely with respect to the direction in which the packages are transported; and a second longitudinal driving device, consisting of at least one brace, fastened to each of the conveyor bars in articulated manner and driven by an oscillating movement that moves the corresponding bar lengthwise forwards and backwards, respectively.

To this end, it is essential for the bars to be able to slide in relation to the support arms of the first transverse driving mechanism, which only serves to bring them nearer to or separate them from the packages, due to which said arms are equipped, at their connection with the bars, with a guide element along which the bars can slide in their longitudinal forward and backward movements. This assembly guarantees that the bars follow a straight-line trajectory in their longitudinal movements, as their movement is guided by the support arm guides, which remain motionless during the longitudinal movement of the bars. The forward or backward movement of the conveyor bars in a straight-line trajectory is fundamental to the correct operation of the packing machines and prevents, amongst other problems, the contents of the packages from being spilt when carried from one station to another in the packing module.

The relative movement between the conveyor bars and support arms of the

first transverse driving mechanism affects the maintenance and working life of some of the machine components, and especially said driving mechanisms. Due to the large number of cycles undergone by the machine, the constant friction between the bars and the support guides eventually wears both components and therefore requires a very strict maintenance of this part of the machine. In particular, appropriate lubrication between the bars and the support guides must be ensured during operation of the machine.

The constant lubrication or greasing of the components coupled with sliding capacity between them represents a drawback difficult to overcome when forming and packing operations must be carried out in sterile environments or under controlled atmospheres, as the previously mentioned mobile parts must be accessible from the exterior for lubrication purposes, which alters the sterile working conditions. At the same time, the excess grease that oozes from the guided couplings impregnates or soils parts of the mechanism, which can once again alter said sterile working conditions.

Explanation of the invention

In order to overcome said drawbacks, a driving device for the type of conveyor bar previously described is disclosed. Fundamentally, the device object of the invention is characterized in that it comprises at least one assembly consisting of a drive lever that can be joined by its upper end to the conveyor bar in articulated manner; a rotation axis, around which said drive lever rotates; a support structure, whereto the drive lever rotation axis is joined; and the means to produce, simultaneous to the rotating movement of the drive lever around its rotation axis, a relative movement between said rotation axis and the upper end of the drive lever or between the rotation axis and the support structure in such a way that, when said drive lever rotates around its rotation axis, in either direction, a corresponding forward or backward movement is transmitted to the upper end of the drive lever, respectively, following a straight-line trajectory that drags the conveyor bar in its first and third longitudinal forward and backward movements when said conveyor bar is coupled to the drive lever.

According to a variation of the invention, the drive lever rotation axis is movably joined to the support structure, following a basically vertical trajectory, and the device further comprises a means of compensation, supported on the same support structure, adapted to force the simultaneous upward or downward movement of the drive lever rotation axis, in either direction, respectively, while

causing the corresponding forward and backward movement following a straight-line trajectory of the upper end of the lever couplable to the conveyor bar.

According to a particularly interesting embodiment of said variation, the drive lever rotation axis is joined to the support structure through a first rotary arm, the rotation axis whereof is solidly joined to said support structure and parallel to the drive lever rotation axis, in such a way that the latter can freely move upwards or downwards following a circular trajectory with its centre in the rotation axis of said first arm.

According to another embodiment, the drive lever rotation axis can move freely along a guide the support structure is equipped with.

In accordance with another characteristic of the variation, the compensation means consists of a second rotary arm, one of the ends whereof is joined to the drive lever in articulated manner while its other end is joined to said support structure in articulated manner, the rotation axes of both articulated connections being parallel to the drive lever rotation axis.

According to a preferred embodiment, the second rotary arm is joined to the drive lever by its lower end, opposite to the upper end of the coupling between the drive lever and the conveyor bar, and the drive lever rotation axis is located in the middle of said lever. Alternatively, the compensation means can consist of a cam element on the outer surface whereon the lower end of the drive lever rests, through a rolling or sliding element, opposite to the upper end of the coupling between said drive lever and the conveyor bar.

According to another variation of the invention, the upper end of the drive lever is retractable, the drive lever, and therefore the distance between its upper end and the drive lever rotation axis, being of variable length .

In another variation of the invention, the drive lever is movably joined lengthwise with regard to the rotation axis, which can move freely along the interior of a guide element built into the drive lever. In accordance with another characteristic of the device according to the invention, the support structure is adapted to rotate around a horizontal axis perpendicular to the drive lever rotation axis, transmitting the rotation movement around said horizontal axis to the end of the lever, in such a way that said bar is in turn moved in its second and fourth transverse movements, when coupled to the drive lever.

Another object of the invention is a flexible packaging conveyor for horizontal

packing machines, designed to hold and transport the packages, which consists of at least one support bar of holding means. Said conveyor is basically characterized in that it comprises two driving devices according to the invention, coupled in articulated manner by their upper ends to said bar in corresponding points of connection, conveniently separated, whereby the simultaneous movement of the respective drive levers is transmitted to said bar.

A horizontal packing machine in accordance with claim 9 is also disclosed.

Brief description of the drawings The attached drawings illustrate, by way of non-limitative example, two variations of the driving device according to the invention, in addition to the embodiment of a conveyor also object of the invention. In said drawings:

Fig. 1 is a schematic elevational view of a driving device according to the invention; Figs. 2a, 2b, 2c, 2d and 2e are a sequence of movements of the device in

Fig. 1 ;

Fig. 3 is a schematic front view of a horizontal packing machine packing module equipped with a conveyor driven by driving devices in accordance with Fig. 1 ; Fig. 4 is a schematic elevational view of a variation of the driving device of the invention; and

Fig. 5 is a partially transparent, side view of the packing module in Fig. 2.

Detailed description of the drawings The driving device 1 of the invention (see Figs. 1 and 4) comprises a drive lever 8 couplable in articulated manner to the bar 2 of a package conveyor 3. The drive lever 8, during its rotational movement around its rotation axis 9 in either direction, will subsequently move the bar 2 forwards or backwards, respectively, when coupled to the drive lever 8. During a simple rotational movement of the drive lever 8 around the rotational axis 9, the upper end 20a of said lever would move following a circular trajectory with its centre in said rotation axis 9 of the drive lever 8. The movement of said upper end 20a would be transmitted to the bar 2 through said articulated coupling, due to which it would move following a circular trajectory. In order to avoid this effect, the driving device of the invention is equipped with compensation means 10 conveniently adapted to move the rotation axis 9 of

the drive lever 8 during its rotation around said axis, all whereof in such a way that the vertical component of the circular trajectory of the upper end 20a of the lever is compensated 10 downwards or upwards, respectively, by a magnitude equal to the vertical component that must be corrected, in such a way that the vertical component of the circular trajectory of the upper end 20a of the lever is compensated by the movement of said axis 9. In other words, when the end 20a of the lever tends to rise or fall in its trajectory, the rotational axis 9 is moved by the compensation means 10 downwards or upwards, respectively, by a magnitude equal to the vertical component that we wish to modify, so that the end 20a of the drive lever moves following a straight-line horizontal trajectory.

Fig. 1 shows in detail a driving device according to the invention, which comprises a drive lever 8 couplable by its upper end 20a to the conveyor bar 2 of a horizontal packing machine. The rotation axis of the drive lever 8 is movably joined to a support structure 11 , which can also support the compensation means 10, as previously explained, that will subsequently move the rotation axis 9 of the drive lever 8 during its rotation around its axis 9.

In the example shown in Fig.1, the rotation axis 9 is joined to the support structure 11 through a first rotary arm 13, the rotation axis 13' whereof is solidly joined to said support structure 11. The rotation axes 13' and 9 of the first rotary arm 13 and the drive lever 8, respectively, are parallel, so that the rotation axis 9 of the lever can move freely upwards or downwards following a circular trajectory with its centre in the rotation axis 13' of said first rotary arm 13. In turn, the compensation means 10 consists of a second rotary arm 12, joined in articulated manner by its end 12b to the lower end 20b of the drive lever 8, located on the other side of the rotation axis 9, while the other end 12a of said second rotary arm is joined in articulated manner to said support structure 11 , the rotation axes of both articulated connections being parallel to the rotation axis 9 of the drive lever 8.

Starting from the position represented in Fig. 1, when the end 12b of the second rotary arm 12 is pulled in the direction indicated by arrow A, the drive lever 8 is forced to rotate around its rotation axis 9, moving its upper end 20a in the direction indicated by arrow B, but simultaneously the same end 12b, and therefore the lower end 20b of the drive lever, is forced to move downwards around the rotation axis of the second rotary arm 12, due to which the rotation axis 9 of the drive lever 8 is also forced to descend. The simultaneous movement of the drive lever around its axis 9 and that of the latter around the rotation axis 13' of the first rotary arm 13 compensate the vertical component of the movement of the upper end

20a of the lever, which from a fixed point of reference, moves following a straight- line horizontal trajectory 4. Inversely, when the end 12b of the second rotary arm 12 moves in the opposite direction to that indicated by arrow A, the upper end 12a of the drive lever 8 will move, from a fixed reference point, following a straight-line horizontal trajectory 6 in the opposite direction to trajectory 4.

The sequence of movements of both the drive lever 8 and the first and second rotary arms 12 and 13, respectively, has been represented in Figs. 2a, 2b, 2c, 2d and 2e. In said sequence, it can be observed that the upper end 20a of the drive lever 8 moves following a straight-line horizontal trajectory, on rotating said lever around its rotation axis 9.

In the example shown in Fig. 4, the rotation axis 9 of the drive lever 8 is assembled with the capacity to move along the interior of a guide element 17 the support structure 11 is equipped with, due to which said rotation axis can move freely upwards or downwards along the interior of the guide element 17, disposed in a straight and vertical position in the example shown in Fig. 4. In turn, the compensation means 10 consists of a cam element 18, on the outer surface whereon the lower end 20b of the drive lever 8 rests, through a rolling element 19. Analogous to the example in Fig. 1 , on rotating the drive lever 8 around its axis 9, the latter is forced to move along the interior of the guide 17 upwards or downwards, in correspondence with the outer profile of the cam 18, by contact of the outer surface of the cam with the rolling element 19 of the lower end 20b of the drive lever 8. It is understood that, as in the previous example, the simultaneous movement of the axis 9 along the guide 17 on rotating the drive lever 8 around said axis 9, compensates the vertical component of the movement of the upper end 20a of the lever, which, from a fixed reference point, moves following a straight-line horizontal trajectory.

Alternatively, instead of assembling the drive lever 8 on the support structure 11 in such a way that its rotation axis 9 can move freely upwards or downwards along the interior of the guide element 17 solidly joined to the support structure 11 , the drive lever 8 can be equipped with a guide element, allowing the guide element to slide resting on a rotation axis 9, in this case solidly joined to the support structure 11.

Although not represented, and with the objective of transmitting a movement following a straight-line trajectory to the upper end 20a of the drive lever 8, another solution consists of using a retractable drive lever, the drive lever, and therefore the distance between its upper end 20a and the rotation axis 9, being of variable length

and even in the case that said rotation axis 9 and the drive lever 8 are firmly joined but in articulated manner, without relative movements through guides as explained previously.

In any case, the articulated coupling between the drive lever 8 and the bar 2 of the conveyor 3 allows the same drive lever 8 to be used to transmit to the bar 2 the transverse movements 15 and 16 with respect to the conveyor 3 or to the direction of package flow 21 (see Fig. 3). To this end, the support structure 11 will be assembled with the capacity to rotate around a longitudinal and horizontal axis 14, preferably perpendicular to the rotation axis 9 of the drive lever 8. The rotation of the structure 11 in either direction is transmitted to the upper end 20a of the drive lever 8, the rotation axis 9 whereof is linked to the same structure 11 , which can be coupled with the conveyor bar 2, separating it from or bringing it nearer to the packages 21 , respectively, while moving said conveyor bar 2 during its transverse movements 15 and 16 when coupled to the drive lever 8. Fig. 3 is a front view of the packing module of a horizontal packing machine, equipped with a conveyor 3 consisting of two parallel bars 2 and 2', equipped with means to hold the packages, between which the packing line passes parallel and at the same distance to both bars 2 and 2'. Said means to hold the packages 21 is formed, for the conveyor 3 represented in Fig. 3, by fixed or retractable rods distributed at regular intervals along the bars 2 and 2', placed opposite each other in both bars.

The parallel bars 2 and 2' simultaneously execute a first longitudinal forward movement, during which the packages move along between two workstations following a straight-line trajectory; a second transverse backward movement 15; a third longitudinal backward movement under vacuum opposite to the direction of package flow; and a fourth transverse forward movement 16. In their longitudinal and transverse movements with respect to the packages 21 , each bar 2 and 2' is driven by at least one drive lever 8 and 8', respectively, supported in a corresponding support structure 11 and 11 ', both adapted to rotate around the longitudinal and horizontal axis 14. The simultaneous rotation of said support structure 11 in opposite directions causes the movement of the bars 2 and 2' as they move forwards and backwards, according to the direction of rotation of said support structures 11.

With regard to the transmission of the longitudinal movement to the bars 2 and 2', Fig. 5 represents a schematic side view of bar 2 of the conveyor 3 of Fig. 3. As can be observed, two drive levers 8a and 8b pertaining to two driving devices 1

and 1 ' according to the invention are coupled in articulated manner to the bar 2 by their upper ends 22a and 22b. A cam assembled on the drive shaft of the machine, not represented, drives a transmission bar 23, in an oscillating movement, which is coupled in articulated manner to the lower end 24 of the drive lever 8b, producing the longitudinal and also oscillating movement of the bar 2, following a straight-line horizontal trajectory, as explained previously in detail. It is expected that only one of the driving devices be controlled by a corresponding transmission bar 23, as shown in Fig. 5, or that both mechanisms are connected, through their respective transmission bars, to the drive shaft of the machine. In the case of the conveyors 3 that comprise a single bar 2, the means to hold the packages consists of pincers distributed at regular intervals along said bar 2..