Apparatus and method for forming caps of paper material

Abstract

The invention relates to an apparatus, machine and method for forming caps made from plant fiber or from a paper material intended to replace common caps made from metal or plastics, such as PET. The apparatus comprises a first mould half and a second mould half. The two mould halves are movable with respect to each other along a longitudinal axis, between a distal position and a proximal position. In the closed position, the first mould half and the second mould half together delimit an impression corresponding to the cap to be formed. A cutting blade to cut the band of plant fiber or of paper material, and a male forming element are provided on the first mould half. A counter cutting blade to cut the band, and a female forming element are provided on the second mould half. The male forming element can be at least partially inserted into the female forming element to deep-draw the cap. To prevent the formed cap from remaining engaged on the male forming element when the apparatus is opened, thus requiring manual unscrewing by an operator, the apparatus is configured with the male forming element rotatable about the longitudinal axis with respect to the first mould half. Thanks to this feature, the fully-formed cap can be unscrewed from the male forming element and consequently ejected from the apparatus automatically without operator intervention.

Description

[0001] Apparatus and method for forming caps of paper material

[0002] Field of the Invention

[0003] The present invention relates to an apparatus and method for forming paper caps, particularly screw caps intended to be screwed onto containers for food or non-food use, in order to replace traditional plastic caps.

[0004] State of the art

[0005] Within the scope of the present invention, the term caps is used to identify closing elements for container, and in particular substantially cylindrical closing elements provided with internal threads for screwing onto the mouth of bottles and containers in general.

[0006] In the food sector, the majority of the market for bottled beverages and drinks, such as water, tea, drinks, juices, fresh-squeezed juices, etc., consists of bottle packages made from polyethylene terephthalate (PET), or Tetrapack®- type multilayer film, closed by caps also made from PET. The caps can be screwed onto the bottles and allow the bottles to be opened and closed again by consumers.

[0007] For example, estimated 100-150 billion caps for packages of Tetrapack®-type multilayer film are produced each year.

[0008] Glass containers closed with metal screw caps are also traditionally used in the food sector, for example for the sale of jams and other preserves.

[0009] The traditional packaging solution with screw caps, made from plastic or metal material, is the most widely used in the world, even in non-food applications. For example, cleanser, cosmetics, lubricating oils, chemical additives, thinners, paints, etc., are often offered to consumers in rigid or semirigid plastic packaging, or in tins closed by caps also made from plastic or metal materials, screwed onto the respective container.

[0010] A problem now known to everyone is that the caps are dispersed into the environment. As a matter of fact, a non-negligible percentage of the caps are dispersed into the environment after use. Not only are the caps dispersed into the environment diverted from the recycling chain but in addition they create lasting pollution, given the very long time required for degradation in nature.

[0011] In order to mitigate this problem, companies producing containers have recently started investigating the possibility of replacing metal and plastic caps with new caps made from a paper material that is fully and rapidly biodegradable.

[0012] Swedish start-up Blue Ocean Closures (www.blueoceanclosures.com) offers caps made from a material comprising 85% plant fiber with additives that provide mechanical seal on the container and create a barrier effect for oxygen and liquids. These caps of paper material are proposed as a recyclable and biodegradable, and therefore environmentally sustainable, alternative to traditional metal and plastic caps in both food and non-food fields, such as in the cosmetic industry.

[0013] The production of caps made from paper material, or otherwise from plant fiber, is currently implemented using a special forming apparatus, starting with a single continuous band of paper or fiber, fed to the apparatus itself. The apparatus comprises a lower stationary mould half and an upper mould half movable with respect to the lower mould half between an open position and a closed position of the mould. The two mould halves interact to define an impression corresponding to the cap to be formed. Basically, when the upper mould half is lowered onto the lower mould half, a portion of the band is cut and shaped and the thread is impressed on the cap. Once the cap is fully formed, the upper mould half is lifted to open the apparatus and allow operators to unscrew the cap from the lower mould half.

[0014] Considering that the apparatus remains occupied and not usable for a new production cycle, until the cap already made is taken from the lower mould half, this production method is slow.

[0015] Clearly, by equipping the apparatus with a plurality of stations so as to produce a plurality of caps during the same processing cycle, all the caps already made will still have to be removed before the production of other caps can begin.

[0016] In light of the above, productivity is related to the speed of the operators who manually unscrew the already formed caps from the lower mould half.

[0017] The Applicant believes that there is room to increase the productivity of fiber or paper caps without compromising their quality.

[0018] The following three documents: US 2429376, US 2400961 and US 3408902, describe solutions known in the art.

[0019] Objects and summary of the invention

[0020] It is therefore an object of the present invention to provide an apparatus, a machine and a method for forming caps made from plant fiber or from a paper material which allow productivity, that is, the number of caps produced per unit time, to be maximized.

[0021] Therefore, a first aspect of the present invention relates to an apparatus according to claim 1 .

[0022] The apparatus produces, from a band made of plant fiber or a paper material, caps of the type able to be screwed. The exact composition of the material depends on the purpose of the cap, which is intended, for example, to close containers in both food and other fields, and is therefore subject to specific chemical and physical composition certifications.

[0023] As an example, the material used to form the caps comprises at least 85% plant fiber and a natural binder such as com starch, and optionally a barrier layer of food-grade silicone. In the food industry the expression paper material generally refers to vegetable parchment or paper laminated in multiple layers or siliconized, or it refers to paperboard.

[0024] The term cap is used herein to identify a screw closing element of containers made from a plastic, metal or glass material, or from composite materials. The cap comprises a flat top wall and a circular side wall that cantileverly extends from the top wall. The thickness of the cap depends on the field of application and can vary between the top wall and the side wall although, preferably, it is uniform throughout the cap. For example, for applications on PET water bottles, the cap can have a uniform thickness of 3-5 mm. At the inner surface of the side wall there is a thread that allows the cap to be screwed to the mouth of the respective container.

[0025] The apparatus comprises a first mould half and a second mould half. The two mould halves are movable with respect to each other on a longitudinal axis between a distal position and a proximal position. The distal position corresponds to the open apparatus and the proximal position corresponds to the closed apparatus. In the closed position, the first mould half and the second mould half together delimit an impression corresponding to the cap to be formed.

[0026] A cutting blade to cut the band of plant fiber or of paper material, and a male forming element are provided, concentrically and in sequence towards the longitudinal axis, on the first mould half. The male forming element is substantially cylindrical and is externally provided with the impression of the thread that has to be impressed on the inner surface of the side wall of the cap.

[0027] A counter cutting blade to cut the band and a female forming element are provided, concentrically and in sequence towards the longitudinal axis, on the second mould half. The female forming element is cylindrical and hollow.

[0028] The counter cutting blade and the female forming element, which are on the second mould half, can be inserted between the cutting blade and the male forming element, which are on the first mould half, and the male forming element can be at least partially inserted into the female forming element in order to deep-draw the cap.

[0029] To prevent the formed cap from remaining engaged on the male forming element when the apparatus is opened, thus requiring manual unscrewing by an operator, the apparatus is configured with the male forming element and / or the female forming element rotatable about the longitudinal axis. Thanks to this feature, the fully-formed cap can be unscrewed from the male forming element and consequently ejected from the apparatus automatically without operator intervention. For this reason, the apparatus comprises a first actuator that imparts rotations to the corresponding forming element at the appropriate time.

[0030] Thus, the proposed solution allows cap production to be automated, thus avoiding manual unscrewing of the newly formed cap. As a result, productivity is increased compared to manual operator intervention, as the time required to eject the cap from the apparatus is greatly reduced, all other factors being equal.

[0031] In the preferred embodiment, the rotatable forming element is the male forming element, while the female forming element is rotationally stationary.

[0032] In the preferred embodiment the counter cutting blade and the female forming element are made in one piece, and the counter blade corresponds to the sharp outer edge of the female forming element. As an alternative, the counter cutting blade and the female forming element can be made as separate and assembled elements, and, if necessary, a relative telescopic-type movement can be provided between them, the counter cutting blade being able to be extracted from the female forming element.

[0033] Preferably, the apparatus comprises an ejector element having the function of ensuring the ejection of the cap from the female forming element, that is, preventing a newly formed cap from getting stuck.

[0034] The ejector element is telescopically mounted on the second mould half, thus being movable relative to the second mould half between a retracted position and a forward position. In the retracted position, the ejector element closes the female forming element on top. In the forward position, the ejector element extends into the female forming element, at least partially occupying its volume designated for cap formation, so as to cause the formed cap to be ejected.

[0035] In the preferred embodiment, the telescopic ejector element is mounted on the second mould half, slides along the longitudinal axis and has an end against which the top wall of the cap is formed, i.e., it defines the abutment surface on which the top wall of the cap is formed. The apparatus comprises a second actuator configured to control the displacements of the telescopic ejector element.

[0036] For example, in an embodiment, the ejector element has a mushroom shape similar to that of a valve for automotive endothermic engines.

[0037] Preferably, the male forming element is damped so as to be inserted into the female forming element and is able to retract just enough to avoid mechanical interference, while continuing to exert the required pressure on the cap being formed, so that the plant fiber material or paper material remains compressed between the male forming element and the female forming element.

[0038] In the preferred embodiment, the male forming element is movable on the first mould half, on the longitudinal axis, between an extended position and a retracted position, in response to the thrust exerted by the second mould half when the material to be compressed is interposed between the two mould halves. The apparatus comprises a preloaded elastic element which counteracts the displacements of the male forming element. The elastic element constantly exerts a thrust on the male forming element in the direction that brings the male forming element to the respective extended position.

[0039] Preferably, the first actuator is an electric motor arranged with its own drive shaft coaxial to the longitudinal axis, and the male forming element is mounted on the electric motor, meaning that the rotations of the electric motor shaft are directly transmitted to the male forming element. Alternatively, if the axial dimension of the apparatus is to be minimized, the actuator could be offset, i.e. positioned not along the longitudinal axis but at a distance from the longitudinal axis, and a transmission system should be prearranged to transmit the rotations to the male forming element, e.g. by means of a kinematic chain with gears or a belt. The same measures can be taken in the case of making the female forming element rotatable.

[0040] In an embodiment, the apparatus is designed to work with bands of fiber or paper material that have been moistened before being sent to the apparatus. In this circumstance, the apparatus comprises heating means configured to heat the male forming element and / or the female forming element to reduce the moisture content of the cap being formed and fix its final shape more effectively. For example, heating means are electrical resistors inserted into at least one of the male forming element and the female forming element.

[0041] Preferably, the female forming element comprises, on its inner surface, a knurl to be impressed on the outer side surface of the cap. The knurl allows the cap to be easily grabbed by the user, for unscrewing and screwing from / onto the respective container.

[0042] In the preferred embodiment, the apparatus comprises an electronic control unit equipped with program means. The control unit is programmed to synchronize the rotation about the longitudinal axis of the male forming element with the opening movement of the apparatus. In addition, the control unit controls the closing and opening of the apparatus, the turning on and off of the heating means, etc. In particular, the control unit controls the opening of the apparatus by causing the rotation of the male forming element to be started when the female forming element is still at least partially fitted on the cap formed, so that the pressure exerted on the cap by the female forming element helps to facilitate the unscrewing of the cap from the male forming portion.

[0043] In the preferred embodiment, the first mould half is stationary and the second mould half is alternately movable along the longitudinal axis.

[0044] The apparatus described above can be defined as single-impression, meaning that it produces a single cap per work cycle, that is, each time the apparatus is closed. Of course, if productivity is to be increased, a machine could be equipped with a plurality of apparatuses to obtain a multiple impression machine.

[0045] Actually, a second aspect of the present invention relates to a machine for producing caps, comprising a lower mould carrier and an upper mould carrier, and comprising two or more apparatuses according to the present invention, described above. The first mould half of all apparatuses is mounted on board the lower mould carrier, and the second mould half of all apparatuses is mounted on board the upper mould carrier. The machine comprises a feeding system to feed a band made of plant fiber or of a paper material. The band is fed to all machine apparatuses, which are arranged either in parallel or in series / parallel. The machine comprises a movement system to move at least one of the mould carriers relative to the other mould carrier, in order to simultaneously close and open all apparatuses.

[0046] The machine can be equipped with the desired number of apparatuses, corresponding to the number of caps to be produced per cycle. To simplify the structure of the machine, a single first actuator can be used to force the rotation of the male forming element of all apparatuses, possibly using a belt drive system.

[0047] In its third aspect, the present invention relates to the method according to claim 13 for forming, from a band of plant fiber or of a paper material, a cap provided with a side wall and an upper wall, wherein there is a thread on the inside of the side wall of the cap.

[0048] The method comprises steps a) to e): a) providing the apparatus described above, b) while closing the apparatus, cutting or die-cutting the band by means of the cutting blade of the first mould half and the counter cutting blade of the second mould half, in order to obtain a blank having dimensions proportional to the dimensions of the cap to be formed; c) while closing the apparatus, deep-drawing the blank by means of the male forming element and the female forming element; d) while opening the apparatus, rotating the male forming element about the longitudinal axis to unscrew the formed cap from the male forming element; e) ejecting the cap formed by the apparatus.

[0049] The blank is a circular disk of material obtained from the band.

[0050] Step b) is implemented by inserting the counter cutting blade into the cutting blade and holding the blank centered with respect to the male forming element, such as holding the blank inside the counter cutting blade to prevent it from being displaced with respect to the longitudinal axis.

[0051] Step c) is implemented by at least partially inserting the male forming element into the female forming element until the blank is shaped to match the impression of the cap, defined by the male forming element together with the female forming element. At this step, the thread is impressed on the inner side surface of the cap.

[0052] If required, at least one of the male forming element and the female forming element is heated during step c) to reduce the moisture content in the fiber or paper material of the cap being formed.

[0053] As explained above, step d) is implemented by synchronizing the opening movement of the apparatus with the rotation imparted to the male forming element, to disengage, by unscrewing, the cap from the male forming element. Synchronization is provided by the control unit.

[0054] Preferably, step d) is implemented while the female forming element is still at least partially fitted on the formed cap.

[0055] Step e) is implemented by means of the cap ejector element and possibly by means of an air jet.

[0056] The apparatus, machine and method described above can be used / implemented to produce screw caps made from plant fiber or from a paper material, which are intended to close containers in food and non-food applications.

[0057] Brief description of the drawings

[0058] Further details of the invention will be evident from the following description made with reference to the attached non-limiting and illustrative drawings, in which:

[0059] - Figures 1-3 are perspective and axisymmetric section views of an apparatus according to the present invention, in three corresponding configurations during use;

[0060] - Figure 4 is an elevation and axisymmetric section view of the apparatus shown in Figures 1-3, in a first configuration, at the beginning of the production cycle of a cap;

[0061] - Figure 5 is an elevation and axisymmetric section view of the apparatus shown in Figure 1-3, in a second configuration;

[0062] - Figure 6 is an elevation and axisymmetric section view of the apparatus shown in Figure 1-3, in a third configuration;

[0063] - Figure 7 is an elevation and axisymmetric section view of the apparatus shown in Figures 1-3, in a fourth configuration;

[0064] - Figure 8 is an elevation and axisymmetric section view of the apparatus shown in Figures 1-3, in a fifth configuration, at the end of the production cycle of a cap.

[0065] Detailed description of the invention

[0066] In the attached figures, an apparatus according to the present invention for forming caps 2 is denoted by reference number 1 (Figure 8).

[0067] As shown in Figure 8, each cap 2 comprises a flat top wall 3 and a side wall 4 with circular section, which cantileverly extends from the flat top wall 3. At the inner surface of the side wall 4 there is a thread 5, either continuous or segmented, which allows the cap to be screwed onto the corresponding container.

[0068] The apparatus 1 comprises a first mould half 6 and a second mould half 7 arranged aligned on a longitudinal axis X. The two mould halves 6 and 7 are susceptible to relative displacements with respect to each other between a proximal position, at which the apparatus 1 is closed and the two mould halves 6 and 7 are at least partially inserted into each other, and a distal position, at which the apparatus 1 is open and the two mould halves 6 and 7 are separated and do not interact.

[0069] In the example shown in the figures, the first mould half 6 is placed below the second mould half 7, and for this reason in the following, the two mould halves 6 and 7 will also be referred to as lower mould half 6 and upper mould half 7.

[0070] In the example shown in the figures, the lower mould half 6 is stationary and the upper mould half 7 is translatable alternately in both directions along the longitudinal axis 7 to close and open the apparatus 1 and thus perform a processing cycle to produce a single cap 2. Alternatively, kinematic inversion can be considered, with the upper mould half 7 stationary and the lower mould half 6 movable, or else both mould halves 6 and 7 movable.

[0071] The first mould half 6, the lower one, comprises a cutting blade 8 formed on a metal support 9. The cutting blade 8 is a circular blade having the function of cutting a disk of material from a band of plant fiber or a band of paper material fed to the apparatus 1 , from which the caps 2 are obtained. The cutting blade 6 is coaxial to the longitudinal axis X and consists of a hole in the support 9, having a sharp edge.

[0072] The first mould half 6 further comprises a male forming element 10 substantially cylindrically shaped which has on its side surface the negative impression 11 of the thread 5 to be made in the caps 2. The inner surface of the cap 2 is formed on the outer surface of the male forming element.

[0073] The male forming element 10 is coaxial to the longitudinal axis X and is inserted into the cutting blade 8. Between the cutting blade 8 and the male forming element 10 there is a gap into which a part of the second mould half 7 is inserted, as will be explained later.

[0074] The male forming element 10 is in turn supported by a supporting column 12 to which it is telescopically constrained, i.e., with the possibility of displacements along the longitudinal axis X between a retracted position and an extended position. In Figures 1-3, the male forming element 10 is shown in the extended position, that is, at the end of travel in extension with respect to the supporting column 12. Specifically, the male forming element 10 is damped: an elastic element, which in the example shown in the figures is a preloaded spring 13, constantly exerts a thrust in the direction that brings the male forming element 10 to the extended position. This expedient allows the male forming element 10 to be returned into the supporting column 12 when longitudinal pressure is applied on the male forming element 10, by the second mould half 7.

[0075] The male forming element 10 is rotatable about the longitudinal axis X in order to unscrew the cap 2 each time it is formed. The supporting column 12 is coupled to a turning platform 14, which may be a supporting element driven to rotate by a remote electric motor, by means of a transmission system, such as a belt drive, or it may itself be an electric motor arranged coaxial to the longitudinal axis X. The turning platform 14 is coaxial to the longitudinal axis X. Regardless of the specific solution chosen, it should be noted that the turning platform 14 can be control-rotated about the longitudinal axis X to cause the male forming element 10 to rotate, clockwise or counterclockwise.

[0076] The second mould half 7, the upper one, comprises a support 15 on which a counter cutting blade 16, also circular and having a diameter complementary to the diameter of the cutting blade 8, is formed. The counter cutting blade 16 is the sharp edge of an annular portion 17 of the support 15. When the upper mould half 7 is lowered onto the stationary lower mould half 6, the annular portion 17 just mentioned is inserted into the support 9 of the lower mould half 6, between the cutting blade 8 and the male forming element 10, thus fitting onto the latter. This movement results in the insertion of the counter cutting blade 16 into the cutting blade 8 and the subsequent die-cutting of a disk of material from the band fed to the apparatus 1 .

[0077] On the upper mould half 7 there is a female forming element configured to define, together with the male forming element 10 when the apparatus 1 is closed, a volume corresponding to the cap 2 to be made, as in a mould.

[0078] In the example shown in the figures, the female forming element consists of the annular portion 17, on the inner surface of which the outer surface of cap 2 is formed. In the figures, there is a knurl 18 on the inner surface of the female forming element 17 intended to be impressed on the side surface 4 of the caps 2, to facilitate gripping by the user.

[0079] As an alternative, the counter cutting blade 16 and the female forming element 17 can be made as separate, assembled coaxial elements. An ejector element 19 having the function of ensuring the removal of the cap 2 from the female forming element 17, once the cap 2 has been formed and the apparatus 1 is opened, is also mounted on the upper mould half 7. In the example shown in the figures, the ejector element 19 is a mushroom-like element, that is, it is a stem that comprises a lower end 20 with an enlarged section. The shape of the ejector element 19 is similar to that of a valve of an automotive endothermic engine. The end 20 of the ejector element 19 has a flat bottom surface that constitutes the ceiling of the female forming element 17. In other words, the outer surface of the upper wall 3 of the cap 2 is formed right on the lower surface of the end 20 of the ejector element 19.

[0080] The ejector element 19 is coaxially inserted into the support 15 and slides along the longitudinal axis X between a retracted position and an extended position. In the retracted position, as can be seen in Figures 1 and 2, the end 20 of the ejector element 19 is flush with the female forming element 17, to allow the cap 2 to be formed; in Figure 3, the ejector element 19 is shown in the extended position, corresponding to the end 20 inserted into the female forming element 17, all the way under the knurl 18. Clearly, in the extended position shown in Figure 3, the cap 2 has been pushed out of the female forming element 17 by the ejector element 19. By returning the ejector element 19 to the retracted position, a new production cycle can be started. Axial displacements of the ejector element 19 are preferably controlled by an electric actuator (not shown), such as a motorized linear guide, but can alternatively be imparted by a pneumatic actuator.

[0081] Figures 4-8 are elevation and axisymmetric section views of the apparatus 1 in corresponding configurations during a production cycle of a cap 2, i.e. showing a sequence of operation of the apparatus 1. For the sake of simplicity, the band 21 of material to be processed is shown only in Figure 4 but the reader is encouraged to consider that the band 21 is continuously fed to the apparatus 1 , with intermittent feeding motion synchronized with the closing and opening movements of the apparatus 1 ; therefore, the band 21 should be understood as also present in Figures 5-8. The band 21 is fed in a plane orthogonal to the longitudinal axis X, which is intermediate between the two open mould halves 6, 7.

[0082] Figure 4 shows a configuration at the beginning of the cycle, in which the band 21 is stationary, the upper mould half 7 is moving along the longitudinal axis X toward the lower mould half 6. A circular blank 22 has been die-cut from the band 21 by the cutting blade 8 together with the cutting counter blade 16, both of which are circular. The blank 22 is a disk of plant fiber or paper material that is held in place on the top by the female forming element 17, on the bottom by the male forming element 10, and on the sides by the cutting blade 8. The male forming element 10 is restrained by the spring 13 in the respective extended position, with respect to the supporting column 12, that is, the spring 13 is extended to the maximum. The ejector element 19 is retracted. In this configuration, the blank 22 is ready to be deep-drawn, as it is sufficient to further close the apparatus 1.

[0083] Figure 5 shows a configuration subsequent to the one shown in Figure 4. The band 21 is stationary, the upper mould half 7 has been further lowered along the longitudinal axis X onto the lower mould half 6 but does not apply pressure. The female forming element 17, which is annular, is inserted between the cutting blade 8 (and the support 9) and the male forming element 10. This configuration corresponds to the male forming element 10 inserted into the female forming element 17 so as to face the flat end 20 of the ejector element 19; the elements 10, 17 and 20 jointly define the impression or forming volume of a cap 2. The male forming element 10 is restrained by the spring 13 in the respective extended position, with respect to the supporting column 12, that is, the spring 13 is extended to the maximum. The ejector element 19 is retracted.

[0084] Figure 6 shows a configuration subsequent to the one shown in Figure 5. The band 21 is stationary, the upper mould half 7 has been fully lowered along the longitudinal axis X onto the lower mould half 6. The female forming element 17, which is annular, is inserted between the cutting blade 8 (and the support 9) and the male forming element 10. This configuration corresponds to the male forming element 10 inserted into the female forming element 17 so as to face the flat end 20 of the ejector element 19; the elements 10, 17 and 20 jointly define the impression or forming volume of a cap 2. The thrust exerted by the upper mould half 7 against the male forming member 10 caused it to move back into the supporting column 12: the spring 13 is compressed and thus the gap 23 is created, which corresponds precisely to the axial travel traveled by the male forming member 10 to be brought to the retracted position, which, in the example shown, corresponds to the abutment against the turning platform 14. The ejector element 19 is still retracted. The pressure exerted by the male forming element 10 and the female forming element 17 on the blank 22 is sufficient to compact the material and impress the final shape of the cap 2.

[0085] The apparatus 1 can be equipped with resistors (not shown) to heat the male forming element 10 or the female forming element 17, or both, in case the initial moisture content of the band 21 is excessive, for example because the band 21 has been previously moistened to facilitate its deformation in the apparatus 1 .

[0086] Figure 7 shows a configuration subsequent to the one shown in Figure 5. The band 21 is still stationary, the upper mould half 7 is moving upward along the longitudinal axis X to open the apparatus 1 and exerts no pressure on the lower mould half 6 and on the male forming element 10. The male forming element 10 has been returned to the extended position by the spring 13. The turning platform 14, or the electric motor 14, has been activated and imparts a rotation to the male forming element 10 about the longitudinal axis X. Since the female forming element 17 has not yet been fully removed from the male forming element 10 and the newly formed cap 2 is still interposed between these two forming elements 10, 17, the rotation of the male forming element 10 causes the cap 2 to be unscrewed from the same male forming element 10, due to the slight restraint that the female forming element applies on the outer surface of the cap 2. In other words, the rotation of the platform / actuator 14 is synchronized with the opening movement of the apparatus 1 , so that the cap 2 does not remain rotationally integral with the male forming member 10 but can actually be unscrewed from the thread 11 , that is, so that the thread 5 can be disengaged from the negative impression 11 present on male forming member 10. As explained above, this is achieved by ensuring that a minimum grip of the forming element 17 on the cap 2 is maintained while the male forming element 10 is rotating.

[0087] The apparatus 1 can be implemented with inverted movements, that is, it can be implemented with the upper mould half 7 rotating about the longitudinal axis X, holding the male forming element 10 rotationally stationary, but the practical implementation would be more complex than the example shown in the figures, due to the presence of the ejector element 19.

[0088] Alternatively, both the mould halves 6 and 7 can be made rotatable to achieve unscrewing of the formed cap 2.

[0089] Turning back to the example shown in the figures, the forming element 10 rotates long enough to completely unscrew the cap 2, which nevertheless remains inserted in the female forming element 17.

[0090] Figure 8 shows the apparatus 1 in the final configuration of the production cycle. The upper mould half 7 is fully raised and separated from the lower mould half 6. The ejector element 19 is brought to the extended position, that is, the end 20 is pushed along the longitudinal axis X into the female forming element 17 in order to eject the cap 2 from the female forming element 17. An air jet supplied by external means pushes away the cap 2 towards a container located near the apparatus 1. A length of the band 21 is fed and stopped, to supply new material to be die-cut in the next cycle of the apparatus 1.

[0091] The apparatus 1 comprises an electronic control unit (not shown) that controls the operation of the apparatus 1 , and in particular of the closing and opening movements, the rotation movement of the rotatable forming element 10, 17, the movement of the ejector element 19, the feeding movement of the band 21 , etc., as explained above.

Claims

CLAIMS1. An apparatus (1 ) for forming caps (2) from a band made of plant fiber or of a paper material, comprising a first mould half (6) and a second mould half (7) which are movable with respect to each other along a longitudinal axis (X) between a distal, open position and a proximal, closed position, and wherein:- in the closed position, the first mould half (6) and the second mould half (7) together delimit an impression corresponding to a cap (2) provided with a side wall (4) and an upper wall (3), wherein on the inside of the side wall (4) of the cap (2) there is a thread (5),- a cutting blade (8) to cut said band and a cylindrical male forming element (10), externally provided with the impression (11 ) of said thread (5), are provided, concentrically and in sequence, on the first mould half (6),- a counter cutting blade (16) to cut said band, a cylindrical and hollow female forming element (17) are provided, concentrically and in sequence on the second mould half (7), wherein the counter cutting blade (16) and the female forming element (17) can be inserted between the cutting blade (8) and the male forming element (10), and the male forming element (10) can be at least partially inserted into the female forming element (17), and wherein at least one of the male forming element (10) and the female forming element (17) is rotatable about the longitudinal axis (X) to achieve unscrewing of the formed cap (2), and the apparatus (1) comprises a first actuator (14) which imparts rotations to the rotatable forming element (10, 17).

2. Apparatus (1 ) according to claim 1 , wherein the counter cutting blade (16) and the female forming element (17) are made in one piece, and the counter cutting blade (16) corresponds to the sharp outer edge of the female forming element (17), or they are made as separate elements and assembled.

3. Apparatus (1) according to claim 1 or claim 2, comprising a telescopic ejector element (19) mounted on the second mould half (7), wherein the ejectorelement (19) is movable with respect to the second mould half (7) between a retracted position, at which it closes the female forming element (17) on top, and a forward position, at which it is inserted into the female forming element (17) to cause the ejection of the formed cap (2).

4. Apparatus (1 ) according to claim 3, wherein the ejector element (19) is mounted on the second mould half (7), slides along the longitudinal axis (X), and has an end (20) against which the top wall (3) of the cap (2) is formed, and wherein the apparatus (1 ) comprises a second actuator configured to control the displacements of the ejector element (19).

5. Apparatus (1) according to any one of claims 1-4, wherein the male forming element (10) is damped.

6. Apparatus (1 ) according to any one of the preceding claims, wherein the male forming element (10) is movable on the first mould half (6), on the longitudinal axis (X), between an extended position and a retracted position, in response to the thrust exerted by the second mould half (7), and the apparatus (1 ) comprises a preloaded elastic element (13), for countering the displacements of the male forming element (10).

7. Apparatus (1 ) according to any one of the preceding claims, wherein the first actuator (14) is an electric motor arranged coaxially to the longitudinal axis (X), and the male forming element (10) is mounted on the electric motor, or the male forming element (10) is mounted on a supporting element which is driven to rotate about the longitudinal axis (X) by the first actuator.

8. Apparatus (1 ) according to any one of the preceding claims, comprising heating means configured to heat the male forming element (10) and / or the female forming element (17).

9. Apparatus (1 ) according to any one of the preceding claims, wherein the female forming element (17) comprises, on the inner surface, an impression of a knurl (18) to be impressed on the outer side surface (4) of the cap (2).

10. Apparatus (1 ) according to any one of the preceding claims, comprising a control unit provided with program means, wherein the control unitis programmed to synchronize the rotation of the male forming element (10) and / or the female forming element (17) about the longitudinal axis (X) with the opening movement of the apparatus (1 ).

11. Apparatus (1 ) according to any one of the preceding claims, wherein the first mould half (6) is stationary and the second mould half (7) is alternately movable along the longitudinal axis (X).

12. A machine for producing caps, comprising a lower mould carrier and an upper mould carrier and comprising two or more apparatuses (1 ) according to any one of preceding claims 1-11 , wherein the first mould half (6) of said apparatuses (1 ) is mounted on board the lower mould carrier and the second mould half (7) of said apparatuses (1 ) is mounted on board the upper mould carrier, and wherein the machine comprises a feeding system to feed a band (21 ) made of plant fiber or of a paper material to all apparatuses (1 ) and a movement system to move at least one of the mould carriers with respect to the other mould carrier, in order to close and open the apparatuses (1 ).

13. A method for forming, from a band (21 ) of plant fiber or of a paper material, a cap (2) provided with a side wall (4) and an upper wall (3), wherein there is a thread (5) on the inside of the side wall (4) of the cap (2), the method comprising: a) providing an apparatus (1 ) equipped with a first mould half (6) and a second mould half (7) which are movable with respect to each other along a longitudinal axis (X) between a distal, open position and a proximal, closed position, and wherein on the first mould half (6) a cutting blade (8) to cut said band (21) and a cylindrical male forming element (10) externally provided with the impression (11 ) of said thread (5) are provided, concentrically and in sequence, and on the second mould half (7) a counter cutting blade (16) to cut said band (21 ) and an annular female forming element (17), are provided, concentrically and in sequence, b) while closing the apparatus (1 ), cutting or die-cutting the band (21 ) by means of the cutting blade (8) and the counter cutting blade (16), in order toobtain a blank (22) having dimensions proportional to the dimensions of the cap (2) to be formed; c) while closing the apparatus (1 ), deep-drawing said blank (22) by means of the male forming element (10) and the female forming element (17); d) while opening the apparatus (1), rotating the male forming element (10) and / or the female forming element (17) about the longitudinal axis (X) to unscrew the formed cap (2) from the male forming element (10); e) ejecting the cap (2) formed by the apparatus.

14. Method according to claim 13, in which step b) is implemented by inserting the counter cutting blade (17) into the cutting blade (8) and holding the blank (22) centered with respect to the male forming element (10).

15. Method according to claim 13 or claim 14, wherein step c) is implemented by at least partially inserting the male forming element (10) into the female forming element (17) until the blank (22) is shaped to match the impression of the cap (2) defined by the male forming element (10) together with the female forming element (17), thereby impressing the thread (5) on the inner side surface (4) of the cap (2).

16. Method according to claim 15, comprising, during step c), heating at least one of the male forming element (10) and the female forming element (17) to reduce the moisture content in the fiber or paper material of the cap (2) being formed.

17. Method according to any one of preceding claims 13-16, wherein step d) is implemented by synchronizing the opening movement of the apparatus (1 ) with the rotation imparted to the male forming element (10) and / or the female forming element (17), to disengage, by unscrewing, the cap (2) from the male forming element (10).

18. Method according to claim 17, wherein step d) is implemented while the female forming element (17) is still fitted on the formed cap (2).

19. Method according to any one of preceding claims 13-18, wherein step e) is implemented by means of an ejector element (19) of the formed cap(2) and possibly by means of an air jet.

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