Folding machine and folding method for joining a lid to a container

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims priority from Italian patent application no. 102022000007688 filed on April 15, 2022.TECHNICAL FIELD

[0002] The present invention relates to a seaming machine for fixing a lid to a container containing, for example, a food product.

[0003] In particular, the present invention relates to a seaming machine, for applying a metallic lid to a cylindrical container, it too metallic, so as to form a can for food beverages, to which the following discussion will explicitly refer without thereby losing generality.BACKGROUND

[0004] In the field of can forming , it is known to use seaming machines different from each other and among these carousel seaming machines, i.e. of the type comprising a structure rotating about a fixed axis and a crown of forming sections coupled to the rotating structure and moved by the rotating structure along a circular seaming path.

[0005] Documents US 2308296 on which the preamble of claim 1 is based, JPH08168837 and WO 2009 / 047659 describe respective cam machines for seaming.

[0006] Each forming section, during the rotation of the structure, receives the container with the relative lid resting on it in a loading station, firmly fixes the lid to the relative container and transfers a formed can into an unloading station.

[0007] For this purpose, each forming section comprises a support plate of the container and a seaming head arranged above the relative plate for bending and pressing the perimeter edges of the lid and of the container together.

[0008] The plate is vertically movable between a lowered loading / unloading position, in which it supports the container in a position spaced from the seaming head, and a raised seaming position.

[0009] The seaming head comprises a motorised reference spindle coaxial to the axis of the plate, and a pair of rollers arranged laterally to the spindle and of which one for bending or curling the edges of the container and of the lid and one for pressing the bent or curled edges.

[0010] The seaming cycle comprises a first operation, during which the outer edges of the lid and of the container are turned downwards on the outside of the container and substantially curled by the bending roller, and a second step, during which the curled edges are radially pressed and forced against each other by the pressing roller, so as to create a hermetic seal.

[0011] The seaming must comply with very strict specifications (some sizes must fall within a tolerance of ± 0.05 mm), therefore it is necessary to carry out very frequent sample checks.

[0012] A first check, carried out more frequently, is carried out on the completely seamed can, i.e. on the cans leaving the unloading station.

[0013] Although less frequently, a second check must also be carried out at the end of the bending operation, so as to check the state of the bending made by the bending roller before the subsequent pressing step is carried out.

[0014] In order to carry out the second check, it is necessary that the pressing roller does not come into contact with the container-lid assembly so as not to make any modifications to the bending carried out by the bending roller.

[0015] In known seamers, the bending and pressing rollers are moved by a mechanical cam, the profile of which defines the desired movement profile of the rollers away from and towards the respective spindle.

[0016] In some known seamers, it is possible to exclude all the pressing rollers present on the machine. Once the check on the bent edges is carried out, the exclusion of the pressing rollers is removed so as to again obtain completely seamed cans.

[0017] In known seamers, the exclusion is obtained by using mechanical cams consisting of two sectors, of which one is fixed for controlling the bending roller and one is movable for controlling the pressing roller. During the normal seaming cycle, the two sectors are kept in fixed operating positions and each one controls the relative roller, whereas during the exclusion, the movable sector is moved in a radial direction to an exclusion or rest position, in which it is not capable of controlling the pressing roller, hence the pressing operation is not carried out.

[0018] Known machines of the type described above, although used, are not much satisfactory from a functional point of view and simultaneously have high manufacturing and maintenance costs. The foregoing is essentially attributable to the fact that the cam, also when the movable sector is arranged in its operating position, is still anyway a cam having a discontinuous profile, i.e. a cam which, however very accurate from a constructive point of view, still has an inevitable discontinuity in the passage zone from one sector to the other. Such discontinuity is responsible for the formation of impacts on the cam follower members, which prejudice the structural and shape stability thereof and the duration of the cam follower members, making indispensable periodic check operations, which obviously entail machine stops and production loss.

[0019] In order to minimize the interruptions and the consequent impacts, to the advantage of the duration of the rollers, an extremely precise mechanical construction is necessary, but as such extremely expensive.

[0020] In addition to this, when the movable sector is arranged in its exclusion position, a macro interruption of the control profile is inevitably generated. In order to prevent mechanical damage to the cam followers and to the various components connected thereto, the rotating structure is rotated at a reduced speed relative to the speed with which it is rotated in the condition of complete seaming.

[0021] Consequently, the check carried out as soon as the bending operation is completed will be carried out on cans machined at a speed different from the normal production speed, introducing potential errors on the verification, since the rotation speed affects the quality of the seaming.SUMMARY

[0022] The object of the present invention is to manufacture a seaming machine for connecting a lid to a container, which allows solving the problems described above in a simple and cost-effective manner.

[0023] A particular object of the present invention is to manufacture a seaming machine, which allows quickly passing from a condition of complete seaming to a condition of partial seaming and vice versa without the initial setting or the efficiency of the machine being compromised or the bending operation being modified.

[0024] According to the present invention a seaming machine for connecting a lid to a container is manufactured, as claimed in claim 1.

[0025] The present invention further relates to a seaming method for connecting a lid to a container.

[0026] According to the present invention, a seaming method is provided, as claimed in claim 5.BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The invention will now be described with reference to the accompanying figures, which illustrate a non-limiting example embodiment thereof, wherein: Figure 1 illustrates, schematically in plan view, and substantially in blocks, a seaming machine manufactured according to the teachings of the present invention; Figure 2 illustrates, in side elevation, on an enlarged scale and with parts removed for clarity, a detail of Figure 1; Figure 3 is a plan view of the detail of Figure 2 arranged in an operating condition; Figure 4 is a figure similar to Figure 3 and illustrates the detail of Figure 3 arranged in a different functional condition; Figure 5 is a sectional view, on an enlarged scale and with parts removed for clarity, of the detail of Figure 1; Figure 6 illustrates, schematically and substantially in blocks, the machining operations of forming sections of the detail of Figure 2 when arranged in the functional condition illustrated in Figure 3; and Figure 7 is a figure similar to Figure 6 and illustrates, schematically and substantially in blocks, the machining operations of forming sections of the detail of Figure 2 when arranged in the functional condition illustrated in Figure 4. DESCRIPTION OF EMBODIMENTS

[0028] In Figures 1 and 2, reference numeral 1 indicates, as a whole, a seaming machine for connecting a metallic closing lid 2 to a container 3, it too metallic, and containing, preferably but not necessarily a food product, and for forming a hermetically closed container 4, for example a can.

[0029] For this purpose, the machine 1 comprises a loading or receiving station 5, in which a succession of lids 2 advanced by a conveyor 6 and a succession of containers 3 advanced by a conveyor 7 converge and in which each lid 2 is superimposed on a relative container 3 in a manner known per se.

[0030] The machine 1 further comprises an unloading station 8 of the hermetically closed containers 4, from which the containers 4 are moved away by means of an evacuation conveyor 9.

[0031] Still with reference to Figure 1, between the conveyors 6, 7 and 9, the machine 1 comprises a seaming assembly 10 for connecting a relative lid 2 to each container 3.

[0032] With reference to Figure 2, the assembly 10 comprises, in turn, a fixed structure 11, a rotating support structure 12 relative to the fixed structure 11 about a fixed axis 13 and a crown of seaming sections 15 carried by the structure 12 and advanced by the structure 12 in succession through the stations 5 and 8 along a circular seaming path P1 (Figure 1).

[0033] With reference to Figure 5, each seaming section 15 comprises a relative support plate 16 for a container 3; the plate 16 rotates about a seaming axis 18 parallel to the axis 13 and defines a support plane P for the container 3 arranged coaxial to the axis 18. The plate 16 is actuated by a known actuator 19 controlled for moving the plate 16 along the axis 18 between a lowered position, illustrated with a dashed line in Figure 5, for loading a container 3 in the station 5 and for unloading the hermetically closed container 4 in the station 8, and a raised position for seaming or connecting the lid 2 to the relative container 3.

[0034] Each seaming section 15 then comprises a relative seaming head 20 arranged above the relative plate 16 (Figure 5).

[0035] Each seaming head 20 comprises, in a manner known per se, a reference spindle arranged coaxially and above the plate 16 and, placed side by side with the spindle, a bending roller 22 and a pressing roller 23 having different external profiles from each other and known per se. The rollers 22 and 23 are coupled, in a known manner, to opposite end portions 24A of a horizontal crosspiece 24, an intermediate portion 24B of which is firmly connected to a lower end section 25A of a driving shaft 25. The driving shaft 25 is coupled to the rotating structure 12 in a rotating manner and in an axially fixed position relative to the rotating structure 12 about a vertical axis 26 by means of a pair of bearings K.

[0036] Each shaft 25 is rotated in an alternating cyclic motion by a motorized cam device 27 common to all the heads 20 and configured to horizontally translate the rollers 22 and 23, in succession and in a known manner, from and towards the relative spindles and fix each lid 2 to the relative container 3.

[0037] The device 27 comprises a crank 29, an end portion 29A of which is firmly connected to an end portion 25B of the shaft 25 and an opposite end portion 29B of which is coupled to a cam follower member 30 of the device 27.

[0038] The device 27 further comprises a control cam 31 having a groove 32 slidably engaged by the cam follower member 30.

[0039] With reference to Figures 2 and 5, the cam 31 is made in one piece and is coupled to the fixed structure 11 in a manner rotating about the axis 13 and in an axially fixed position by means of pairs of bearings 31A.

[0040] The cam 31 is rotated by a linear actuator 33, between two extreme angular end-of-stroke positions, of which a retracted one illustrated in Figures 2 and 3 and an advanced one illustrated in Figure 4, wherein the cam 31 is rotated counter-clockwise and towards the unloading station 8 by a predefined angle X. Preferably, the angle X ranges from 75° to 85° and is conveniently equal to 80°.

[0041] Conveniently, but not necessarily, the linear actuator 33 is a pneumatic piston, which is arranged above a horizontal plate 11A of the fixed structure 11 and, in turn, arranged above the cam 31. The actuator 33 has a jacket 34 hinged to the fixed structure 11 and an output rod 35 coupled to the cam 31 by means of a vertical pin 37 integral with the cam 31 and sliding in a curved slot 38 obtained through the plate 11A. The curved slot 38 defines a guide for an intermediate section of the pin 37 and is configured in such a way as to define two angular shoulders angularly spaced from each other so as to stop the intermediate section in two extreme angular end-of-stroke positions angularly spaced from each other by the angle X (Figures 3 and 4).

[0042] Still with reference to Figure 5, the cam 31 is held in the two angular end-of-stroke positions in a releasable manner by respective vertical blocking pins 39, each of which slides through a relative through opening 40 obtained through the plate 11A and is vertically movable under the thrust of a relative pneumatic actuator 41 fixed to the plate 11A (Figures 2,3, and 4) between a lowered blocking position, in which it makes the cam 31 integral with the fixed structure 6 (Figure 5) and a raised position, in which it allows the cam 31 to freely rotate relative to the fixed structure 11.

[0043] In use, by keeping the cam 31 in its retracted position (Figures 2 and 3), the machine 1 behaves like a traditional seaming machine, in which each of the forming sections 15 during their movement along the path P between the loading station 5 and the unloading station 8 produces a complete seaming, i.e. its own hermetically closed container 4 according to the sequence of operations illustrated in Figure 6. Specifically, after the loading station 5, and once a period is passed in which the plate 16 is raised and the roller 22 approaches the container 3, represented by sector A1, the bending operation of the perimeter edges 43 of the container 3 and of the lid 2 (Figure 5) by the roller 22 starts. The bending operation is represented by sector A of Figure 6.

[0044] During the bending operation, the plate 16 remains in its raised position, as indicated by sector B, the roller 22 carries out the bending of the perimeter edges 43, whereas the pressing roller 23 is kept inactive, as shown by sector C still in Figure 6.

[0045] Once the bending operation is ended, after a period indicated by sectors D, in which the roller 22 moves away from the bent edges 43 and the roller 23 approaches the bent edges 43, the pressing operation of the bent edges 43 by the roller 23 and represented by sector E starts. During the entire pressing operation, the plate 16 remains raised (sector B).

[0046] Once the pressing operation is completed and before reaching the unloading station 8, the plate 16 returns to its lowered position (sector B1), the roller 23 moves away from the container 3 (sector E1) and in the station 8 the hermetically closed container 4 is transferred to the evacuation conveyor 9 and evacuated. Following the evacuation and when provided for, all the planned checks are carried out at the end of the seaming so as to ascertain the optimality of the seaming of the edges 43 and the correct sealing of the containers 4.

[0047] Whereas, when the check on the bent edges 43 is required, the blocking pins 39 are carried into their retracted position, releasing the cam 31 from the constraint with the fixed structure 11, after which the actuator 33 is activated and rotates the cam 31 counter-clockwise in Figure 3 moving it into its advanced position, illustrated in Figure 4. In this manner, sectors A, A1,C,D,E and E1 are rotated counter-clockwise, as is visible in Figure 7, by the angle X, excluding or making in actual fact non-executable the pressing operation of the bent edges 43 represented, as mentioned in the foregoing, by sector E. In particular, in Figure 7 it is immediately evident that the rotation of the cam 31 in a counter-clockwise direction and towards the unloading station 8 and the keeping of the cam 31 in the rotated end-of-stroke position, in actual fact delays the start and the end of the bending operation (sector A), keeping unchanged the bending cycle followed in the complete seaming, producing, in actual fact, an intermediate semi-finished product 4A.

[0048] Still in Figure 7, it is possible to see that the value of the angle X of rotation of the cam 31 is such that before the start E2 of what should be the pressing operation (sector E), the bent edges 43 of the intermediate semi-finished product 4A are spaced vertically from the seaming head 20 since the plate 16 at such instant E2 is already in a lowered position and spaced from the relative seaming head 20.

[0049] In general, the value of the angle X is such that when the start of the pressing operation is planned, the pressing roller 23 does not find or does not come into contact with the bent edges 43 so that the pressing roller 23 will carry out a "blank" pressing operation.

[0050] In an optimization example of the seaming cycle, the blank pressing operation starts when the plate 16 is approximately halfway its descent stroke towards its lowered position. Obviously, and still for a matter of optimizing the seaming cycle or on the basis of the geometric features of the bent edges 43, the instant of absence of contact of the roller 23 with the bent edges 43 can be modified with reference to the position assumed by the plate 16 between the raised and lowered positions. For example, still from the graph of Figure 7 it is apparent that following the rotation of the cam 31, the moving away operation of the bending roller 22 from the container 3 is kept unchanged, hence the angle X of rotation can be such that the moving away operation ends after the plate 16 begins its descent towards its lowered position.

[0051] Still in Figure 7, it is apparent that the angle X of rotation of the cam 31 is such that the instant E2 of the start of what should be the pressing operation is arranged before the intermediate semi-finished product 4A, i.e. with only the edges bent, reaches the unloading station 8.

[0052] From the foregoing it is evident that the simple rotation of the entire control cam 31 about the axis 13 towards the unloading station 8 by a predetermined angle allows arranging all the forming sections 15 in the condition to release in the unloading station 8 an intermediate semi-finished product 4A in which the edges 43 have only been subjected to the bending operation. Such intermediate semi-finished products 4A can therefore be subjected to the planned check operations.

[0053] In this regard it is important to note that with respect to the known solutions, in the described machine 1, due to the rotation of the entire cam 31, the bending operation of the edges is carried out exactly in the same manner and especially at a rotation speed of the rotating structure 12 which is exactly the same at which the rotating structure 12 is rotated during the complete seaming. It follows that the bending state of the edges examined following the exclusion of the pressing operation corresponds exactly to that obtained at the end of the bending operation in the complete seaming cycle.

[0054] In addition to this, still with respect to the known solutions, in the described machine 1, the cam 31 is never modified from a geometrical or dimensional point of view for excluding the pressing operation, but simply rotated. Consequently, in the machine 1 there are no discontinuities and the latter cannot occur in the profile for controlling the rollers 22 and 23 preventing, in such manner, any bouncing of the cam follower and the consequent onset of stresses and vibrational states present, instead, in the known solutions.

[0055] From a constructive point of view, the described machine 1 is, still with respect to the known solutions, constructively simple, easily controllable and has reasonable costs. The exclusion of the pressing operation is obtained, in fact, by means of the mere actuation of a single linear actuator which rotates the cam 31 between two end-of-stroke angle positions defined by mechanical stops.

[0056] From the foregoing it is then evident that under no condition are the settings of the machine 1 lost and periodic check operations are not necessary.

[0057] From the foregoing it is evident that modifications and variations can be made to the described machine 1 without thereby departing from the scope of protection defined by the claims.

[0058] In particular, the actuator 33 could be different from the one indicated by way of example and be replaced for example by a linear electric motor or by a rotary electric motor connected to the cam 31 directly or through a mechanical transmission.

[0059] Furthermore, the machine 1 could comprise a number of forming sections different from that represented in the accompanying figures.

[0060] Finally, the angle X can be varied by a person skilled in the art on the basis of his / her knowledge so as to optimize both the complete seaming cycle and the partial cycle without pressing also depending on the type of seaming to be obtained.

Claims

1. Seaming machine for connecting a lid to a container, the machine (1) comprising a fixed structure (11), a rotating structure (12) relative to the fixed structure (11) about a fixed vertical axis (13) and a plurality of seaming sections (15) carried by said rotating structure (12); each forming section comprising a support plate (16) for a container (3) and a seaming head (20); the plate (16) being movable along a moving vertical axis (18) in opposite directions and relative to the head (20) between a lowered position and a raised position; each seaming head (20) comprising a rotating reference spindle arranged coaxially and above said support plate (16) and a bending roller (22) and a pressing roller (23) having different external profiles from each other placed side by side with the spindle; the machine (1) further comprising a mechanical operating cam (31) made in one piece, carried by said fixed structure (11) and configured to move said bending and pressing rollers (22, 23) crosswise to said moving vertical axis (18) away from and towards said spindle, characterised in that said cam (31) is coupled to said fixed structure (11) in a manner rotating about said fixed vertical axis (13) and in that of comprising motorised actuator means to rotate said mechanical cam (31) between an operating position of complete seaming of the lid (2) to the container (3) and a position of partial seaming of the lid (2) to the container (3).

2. Machine according to claim 1, characterised by comprising mechanical positioning means for blocking said cam (31) relative to said fixed structure (11) in said operating position and in said position of partial seaming.

3. Machine according to claim 2, characterised in that said mechanical positioning means comprise a guide slot (38) .

4. Machine according to any one of the preceding claims, characterised in that said actuator means comprise a linear actuator (33).

5. Seaming method for connecting a lid (2) to a container (3) using a seaming machine (1) as defined in claim 1, the method comprising the steps of arranging a container (3) over a rotating support plate (16), of superimposing a lid (2) on said container (3), of carrying out, by means of a seaming head (20), a bending operation of the perimeter edges (43) of the container (3) and of the lid (2), of carrying out a subsequent operation of pressing said perimeter edges (43) against each other producing a container (4) closed by the lid (2) and of moving the closed container (4) into a pick-up station of the closed container (4) arranging the support plate (16) in a lowered evacuation position in which the closed container (4) does not interfere with the seaming head (20); the method comprising the further step of carrying out, following the bending operation, an operation of excluding said pressing step to obtain in the evacuation station an intermediate semi-finished product in which the lid (2) and the container (3) are partially seamed to each other, characterised in that said exclusion step is carried out by rotating a mechanical cam (31) for controlling the bending and pressing operations about a fixed axis (13) towards the pick-up station and by a given angle such that before the start of the pressing operation the bent edges (43) of the intermediate semi-finished product are spaced vertically from the seaming head (20).

6. Method according to claim 5, characterised in that said bending operation is followed by a step of moving a bending roller (22) away from a reference spindle, said given angle being such that said step of moving away starts before the support plate (16) starts its descent towards its lowered position.

7. Method according to claim 5 or 6, characterised in that said given angle is such that said pressing step starts before the intermediate semi-finished product reaches the evacuation station.

8. Method according to any one of claims 5 to 7, characterised in that said given angle is such that the pressing operation starts when the plate (16) is arranged in a substantially median position between its raised seaming position and its lowered transfer position.