Apparatus and method for testing the airtightness of containers each closed by a membrane

Abstract

An apparatus for testing the airtightness of containers (1) each closed by a membrane (2) comprises a deformation unit (15) configured to exert a deforming action on a plurality of containers (1), and a detection unit (40) for detecting the deformation of the membrane (2) of the containers (1) subjected to the deforming action. The deformation unit (15) comprises a plurality of deformation devices (20), and each of the deformation devices (20) is individually associated with a single corresponding one of the plurality of containers to exert a deforming action.

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for testing the airtightness of containers each closed by a membrane.

[0002] The entire content of the Italian patent application No. 102022000012308 titled "Method and apparatus for testing the tightness of a container closed by a membrane" filed by the present applicant on June 10, 2022, is considered to be incorporated herein.

Background Art

[0003] The present invention is preferably applicable, but not limited to, the field of manufacturing individual containers such as yogurt containers, dessert containers, cups for cooked food, and capsules for extractable products such as coffee. References to this field can be made in the following description without loss of generality.

[0004] Therefore, in this specification, the term "capsule" is intended to refer to a product formed by a container provided with a closing membrane.

[0005] Typically, containers in this technical field are products having the shape of a cup-shaped element, having a substantially inverted conical shape with the top cut off or an equivalent shape, with the widest part where the opening of the container is provided being upward, and are typically formed from a polymeric material.

[0006] In the manufacturing process of capsules, after the container filling step of introducing an extractable product into the container through the opening, the container is sealed by applying a membrane having the function of a closing lid with a layered structure, which is fixed to the edge of the container defining the opening.

[0007] Typically, an airtight closure of the container is obtained by a sealing operation that includes welding and / or gluing, or both. This allows the contents of the capsule, as well as the inert protective atmosphere that can be introduced therein, to be permanently separated from the external atmosphere until at least the removal or piercing of the closure membrane, i.e., the piercing of the container during use of the capsule if provided.

Summary of the Invention

Problems to be Solved by the Invention

[0008] In this specification and the appended claims, unless otherwise expressly stated, several terms and expressions are considered to have the meanings represented by the definitions described below.

[0009] The term "membrane" means an object having a thin sheet structure. This is intended to close an opening and is prone to deformation as a result of changes in internal or external pressure acting on the opening.

[0010] "Deformation of the membrane" means a change in the shape of the membrane. Here, at least a part of the membrane is spaced apart from the reference plane of the container, for example, the plane defined by the edge of the container to which the membrane is attached, and the distance therebetween perpendicular to the reference plane is at least several millimeters.

[0011] A container can be said to be "sealed" when it is airtight, i.e., when gas / air exchange between the inside and outside of the container itself is not possible.

[0012] In the capsule packaging process, generally, a step of testing the airtightness of a container closed by a film is provided. This is carried out after the filling and sealing steps. In fact, ensuring the integrity of the airtightness of the capsule is very important to prevent contamination and oxidation of the product contained therein, or the possibility of leakage of the contents themselves from the capsule. Defects that may impair the airtight closure can be due to, for example, rupture or tearing of the container and / or the closing film, and / or interruption of the welding or bonding area between the film and the container.

[0013] Known test systems provide subjecting the container to a compression, for example a deformation action by local constriction, in a section of the handling path where the inspection station is arranged. A load sensor is installed within the inspection station and arranged to contact the film during the transfer of the container, detecting changes in the pressure inside the container acting on the film. Such a change in the internal pressure induced by the constriction action tends to induce, for example, the expansion of the film itself and actually deform the film. Since the pressure inside the container changes due to a decrease in airtightness caused by the escape of air from the container, any decrease in airtightness can be recognized based on the change in pressure detected by the inspection system, taking into account the possibility of rejection of the container.

[0014] The applicant has been able to observe how important the deformation action of the container is for the realization of an effective control system for detecting any decrease in the airtightness of the container.

[0015] The applicant has first found that, since a plurality of containers are typically handled along a production line and arranged, for example, in a single row or a plurality of rows configuration, in order to adapt the step of testing the airtightness to the handling time and speed of the containers imposed by a production cycle typically designed for high production capacity, the action of deforming the containers should be exerted simultaneously on a plurality of containers.

[0016] Furthermore, the Applicant was able to observe that both the degree and duration of the deformation action exerted on each container are factors related to the system for testing airtightness. On the one hand, in fact, the force to which a deformation that must not actually break the container is applied is proportional with respect to the increase in internal pressure, if a sealed container is mentioned, and this internal pressure causes the deformation of the membrane. On the other hand, the time for applying a deformation force to the container must necessarily conform to the cycle time of the production line, but since it affects the amount of air escaping from the container in case of a defect, this is also an important factor. In fact, the longer the time for applying the deformation force, the greater the amount of air coming out of the opening characterizing the defect, and as a result, the smaller the size of the detectable opening. Therefore, this factor is decisive for identifying a decrease in airtightness related to the presence of openings having extremely small sizes.

[0017] The Applicant understood that the more uniform the deformation force applied from container to container, the more accurately and with higher reliability a defect can be recognized. Also, in order to achieve such uniformity, it is desirable to avoid as much as possible that the containers subjected to the deformation action influence each other. For example, it is also understood that it is desirable to prevent a container from being able to influence the deformation force applied to other containers by reacting to the deformation action, especially in case of the presence of a defect.

[0018] Therefore, the Applicant recognized that the uniformity of the deformation force applied to a plurality of containers subjected to a method for testing airtightness is obtained by applying a deformation action to the containers substantially independently of each other.

[0019] The applicant has finally set up a deformation unit for deforming a container equipped with a plurality of deformation devices. In this deformation unit, each deformation device is individually associated with a single corresponding container among the plurality of containers, thereby ensuring that as uniform a deformation action as possible is applied to all of the plurality of containers to be subjected to the airtightness test, and thereby enabling higher accuracy and result reliability to be obtained in the recognition of airtightness that can be classified as a defect.

Means for Solving the Problems

[0020] Therefore, in its first aspect, the present invention is directed to an apparatus for testing the airtightness of containers each closed by a film.

[0021] Preferably, the apparatus comprises a deformation unit.

[0022] Preferably, the deformation unit is configured to exert a deformation action on a plurality of containers.

[0023] Due to the deformation action, in the case of a sealed container, the pressure level inside the container rises.

[0024] Preferably, the apparatus comprises a detection unit for detecting the deformation of the film of each container subjected to the deformation action.

[0025] Preferably, the deformation unit comprises a plurality of deformation devices.

[0026] Preferably, each deformation device is individually associated with a single corresponding container among the plurality of containers in order to exert a deformation action.

[0027] In its second aspect, the present invention is directed to a method for testing the airtightness of containers each closed by a film.

[0028] Preferably, the method includes providing a deformation unit including a plurality of deformation devices configured to exert a deformation action on each of a plurality of containers.

[0029] Preferably, the method includes setting up a detection unit for detecting deformation of the film of each container subjected to the deformation action.

[0030] Preferably, the method includes individually associating each deformation device with a single corresponding container among the plurality of containers in order to exert the deformation action.

[0031] Preferably, the method includes detecting deformation of the film of each container subjected to the deformation action in order to test the airtightness of the container.

[0032] Due to these features, the deformation action can be applied to each container independently of one another. Thereby, with proper control of the deformation devices, the uniformity of the deformation force applied to all of the plurality of containers subjected to the airtightness test is ensured.

[0033] Furthermore, due to the fact that each deformation device is individually associated with a single corresponding container, one possible failure of a device does not affect the other devices. Thus, the continuity of the operation of the entire device is ensured without requiring interruption of the production line.

[0034] In at least one of the above-described aspects, the present invention may further have at least one of the preferred features described below.

[0035] In a preferred embodiment, the device further includes a conveying device for conveying a plurality of containers toward the detection unit.

[0036] Preferably, the plurality of deformation devices are mounted on the conveying device.

[0037] Preferably, each deformation device includes a pair of pressing elements between which the corresponding container can be disposed.

[0038] Preferably, the pressing elements are articulated on respective supports so as to be subjected to displacement movements from and to the operating position. Preferably, the pressing elements in the operating position exert an action of deforming the corresponding containers.

[0039] Preferably, the displacement movements of the pressing elements from and to the operating position are rocking movements.

[0040] In a preferred embodiment, the device comprises means for controlling the displacement movement of each pressing element.

[0041] Preferably, the control means comprise a cam mechanism.

[0042] Preferably, the cam mechanism includes respective cam follower elements. Preferably, the cam follower elements are rotatably supported on each pressing element. Preferably, the cam follower elements are surface-coupled to a cam profile that is common to a plurality of deformation devices in particular.

[0043] Thanks to these features, a uniform and controlled deformation force can be applied to each of the containers associated with the respective deformation devices.

[0044] Preferably, the cam profile is mounted on a fixed frame that supports the conveying device.

[0045] Preferably, the device comprises a pair of cam profiles respectively arranged on both lateral sides of the conveying device in the lateral direction with respect to the longitudinal extending direction of the conveying device.

[0046] In this way, in the control of the cam follower elements, a constructive simplification is obtained in that one of the pair of cam profiles is dedicated to the movement in one direction of the rocking of a part of the rocking pressing element, and the other cam profile on the opposite side of the pair of profiles is dedicated to the movement in the other direction of the rocking of the remaining part of the rocking pressing element.

[0047] Preferably, the pressing element includes a surface having a concave profile intended to come into surface contact with the container.

[0048] These features improve the holding stability of the container between the pair of pressing elements of the deforming device.

[0049] In a preferred embodiment, the deforming device is configured to exert a deforming action on the corresponding container while the container is being handled along a handling path.

[0050] In this way, the time required for the step of testing airtightness is at least partially and substantially occupied within the time required for the completion of the production cycle of the capsule.

[0051] In a preferred embodiment, each of the pair of pressing elements associated with the corresponding container is configured to exert a deforming action including its respective constriction. The two constricting actions exerted by the pair of pressing elements are carried out substantially simultaneously on the container on both diametric sides of the container.

[0052] Preferably, the container closed by a membrane is a capsule containing a powder for extracting a beverage, more preferably coffee powder.

[0053] It should be noted that some of the steps of the method described above may be independent of the described order of execution. Furthermore, some steps may be optional. Furthermore, some steps of the method may be executed repeatedly and may be executed in series or in parallel with other steps of the method.

Brief Description of the Drawings

[0054] The solution will become more apparent from the following detailed description of embodiments of the solution shown non - limitatively with reference to the accompanying drawings.

Figure 1

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Figure 3

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DETAILED DESCRIPTION OF THE INVENTION

[0055] Referring to the figures, an apparatus for testing the airtightness of a container 1 closed with a film 2, manufactured according to the present invention, is shown generally by reference numeral 100.

[0056] In this preferred embodiment, the container 1 is configured to manufacture capsules for extractable products such as coffee powder. The container 1 has a conical shape with its top cut off, and is manufactured such that the wider part with an opening 3 communicating with the cavity of the container 1 is at the top. Individual products are introduced through the opening 3.

[0057] An edge 4 defining the opening 3 is provided annularly on the container 1. A closing film 2 is fixed to the edge 4 by an operation including, for example, adhesion or welding, or both.

[0058] The fixing of the film 2 is performed to obtain an airtight closure of the container 1 in order to enable the contents of the capsule and any inert protective atmosphere that may be inserted therein to remain permanently separated from the external atmosphere, preferably until the stage of using the capsule.

[0059] The device 100 includes a conveying device 10. The conveying device 10 has the shape of a conveyor belt and is configured to handle a plurality of containers 1 arranged on the conveyor belt by a supply device (not shown) from an inlet region to an outlet region along the conveying direction F. Here, the containers 1 that have completed the step of testing airtightness are picked up in the outlet region and transported to subsequent processing steps in the capsule production cycle.

[0060] In this preferred embodiment, the containers 1 are handled in two laterally arranged rows by the conveying device 10. Each row includes a plurality of containers 1 aligned at a constant pitch along the conveying direction F (which is linear in this embodiment). The containers 1 are transported with their respective bottoms located on the conveying device 10 on the opposite side of the film 2 in the vertical direction.

[0061] The device 100 also includes a deformation unit 15 configured to exert a deforming action on a plurality of containers 1 suitable for testing airtightness.

[0062] The deformation unit 15 includes a plurality of deformation devices 20. Each deformation device 20 is individually associated with a single corresponding container 1 to exert a deforming action.

[0063] Each deformation device 20 is attached to the conveying device 10 and includes a pair of a plurality of pressing elements 21. The corresponding container 1 remains arranged between the pair of the plurality of pressing elements 21 while being handled on the conveying device 10.

[0064] Each pair of the pressing elements 21 is articulated on a respective support 22 integrated with the conveying plane of the conveying device 10. By being articulated around a respective rocking axis directed perpendicular to the conveying direction F, each pressing element 21 is displaceable from and to an operating position where it exerts a deforming action by locally squeezing the container 1. More specifically, each container 1 is subjected to a squeezing action including two squeezing actions performed substantially simultaneously on both diametric sides of the container 1 by the respective pressing elements 21.

[0065] To control the rocking movement of the pressing element 21, a control device 25 is provided which comprises a cam mechanism including a cam follower element 26 coupled to a cam profile 27.

[0066] The cam profile 27 is attached to a fixed frame 28 that supports the conveying device 10.

[0067] More specifically, the cam follower element 26 is composed of corresponding rollers rotatably supported on the corresponding pressing element 21 around a rotation axis oriented in a direction perpendicular to the conveying direction F. The cam profile 27 is defined on a longitudinally extending track along the conveying direction F, to which the cam follower roller 26 is superficially coupled. In this way, by means of an appropriate shape of the cam profile 27, for example including a parallel portion inclined with respect to the conveying direction F, the cam follower roller 26 is displaced transversely with respect to the conveying direction F. Such movement generates a rocking from and to the operating position of the pressing element 21 during handling of the container 1 in the conveying direction F by providing an appropriate lever arm between the articulation axis of the cam follower roller 26 and the articulation axis of the pressing element 21.

[0068] In each container 1 subjected to the deformation action, a pair of pressing elements 21 are rocked around their respective rocking axes in opposite directions. By rocking towards the operating position, each pressing element 21 exerts its respective squeezing action on the corresponding container 1. The two squeezing actions are exerted substantially simultaneously on both diametrically opposite sides of the container 1.

[0069] Reference numeral 21a denotes a surface having a concave profile of the corresponding pressing element 21 intended to come into superficial contact with the container 1.

[0070] Referring to FIG. 3, in this preferred embodiment, since the handling of two horizontally arranged rows of containers 1 is provided, the control of the pressing element 21 is carried out in a constructive and functionally effective manner as follows.

[0071] Each pair of containers 1 includes a first container and a second container that move side by side along the conveying direction F, and is subjected to the deformation action of a pair of first pressing elements 21 and a pair of second pressing elements 21.

[0072] The pair of first pressing elements 21 acts on the first container, and the pair of second pressing elements 21 acts on the second container. The pressing elements of the pair of first pressing elements 21 and the pressing elements of the pair of second pressing elements 21 are arranged on the same side of a pair of containers 1 so as to be adjacent to each other, and can swing integrally with each other around a common swing axis. The control of this swing is performed by a cam follower roller 26 coupled to the track of a cam profile 27 arranged on one side of the conveying device 10.

[0073] Similarly, the other pressing element 21 of the pair of first pressing elements 21 and the other pressing element 21 of the pair of second pressing elements 21 are arranged so as to be adjacent to each other, and can swing integrally with each other around a corresponding common swing axis. The control of this swing is performed by a corresponding cam follower roller 26 coupled to a second track of a cam profile 27 arranged on the other side of the conveying device 10.

[0074] In other words, on this other side of the conveying device 10, a second track of a cam profile 27 to which a corresponding cam follower roller 26 is coupled is arranged in mirror symmetry.

[0075] However, it should be noted that based on this configuration, each pair of pressing elements 21 is configured to act on a single container 1.

[0076] Furthermore, each pair of containers 1 that move side by side along the conveying direction F is subjected to the action of a corresponding pair of deformation devices 20. Its control is performed by a cam mechanism and is common to each other.

[0077] It should also be noted that, by means of a cam profile 27 common to all the deforming devices 20, in each deforming device 20 it is possible to apply the same movement of the vibration of the pressing element 21 from and to the operating position where the deforming action on the corresponding container 1 is exerted. Thereby, the uniformity of the deforming force applied to the container 1 is ensured.

[0078] Reference numeral 30 denotes a device for handling a plurality of abutting elements 31. Each abutting element 31 is configured to exert an abutting action on the membrane 2 of the corresponding container 1, and cancels the deformation of the membrane 2 caused by the squeezing deformation action exerted by the pressing element 21.

[0079] The handling device 30 is arranged at a position overlapping the conveying device 10 and is configured as a closed-loop belt between a pair of return wheels 32 to which the abutting elements 31 aligned at a constant pitch are attached in a moving direction parallel to the conveying direction F. In the handling device 30, an active branch 30a is provided between the return wheels 32. The active branch 30a is rotated at a predetermined interval at a position facing the container 1. Thereby, the abutting element 31 can exert the action of abutting the membrane 2 when being transferred along the active branch 30a.

[0080] Downstream of the handling device 30 with respect to the conveying direction F, the device comprises a detection unit 40 configured to detect at least one parameter related to the membrane profile 2, in particular when the abutting action exerted by the abutting element 31 has stopped.

[0081] Advantageously, the detection unit 40 comprises at least one optical device 41 for non-contact measurement of the membrane 2.

[0082] As an example of the optical device, a photoelectric sensor, particularly an analog type laser sensor, can be mentioned.

[0083] During the transfer of the container 1, the optical device 41 is arranged to detect the profile of the film 2, for example a series of points on the surface of the film 2, at a predetermined sampling frequency of the read values being carried out. It is also provided that sensors corresponding to each row of the container 1 are provided.

[0084] In another embodiment, the optical device may include a video camera or a camera configured to detect the film profile 2 through analysis of the image acquired by the optical device 41.

[0085] Furthermore, the device 100 comprises a control unit 50 schematically shown in FIG. 2. This is configured to compare the parameters related to the film profile 2 with a predetermined threshold value and verify whether the hermeticity of the container is classified as poor.

Claims

1. An apparatus for testing the airtightness of containers (1) each closed by a membrane (2), comprising a deformation unit (15) configured to exert a deforming action on a plurality of said containers (1), and a detection unit (40) for detecting deformation of said membrane (2) of said container (1) subjected to said deforming action, characterized in that, said deformation unit (15) comprises a plurality of deformation devices (20), each of said deformation devices (20) being individually associated with a single corresponding one of said plurality of containers (1) for exerting said deforming action. Apparatus.

2. The apparatus according to claim 1, further comprising a transport device (10) for transporting said plurality of containers (1) towards said detection unit (40), wherein a plurality of said deformation devices (20) are mounted on said transport device (10).

3. Each of said deformation devices (20) comprises a pair of pressing elements (21) between which a corresponding said container (1) is disposed, said pressing elements (21) being articulated on respective supports (22) so as to be subjected to a displacement movement from and to said operating position, said pressing elements (21) in said operating position exerting an action of deforming a corresponding said container (1).

4. The apparatus according to claim 3, wherein the displacement movement of said pressing elements (21) from and to said operating position is a rocking movement.

5. The apparatus according to claim 3 or 4, further comprising a control device (25) for controlling the respective displacement movement of said pressing elements (21), said control device comprising a cam mechanism, said cam mechanism including a corresponding cam follower element (26), said cam follower element (26) being rotatably supported on said pressing element (21) and being surface-coupled to a common cam profile (27) for a plurality of said deformation devices (20).

6. The apparatus according to claim 5, wherein the cam profile (27) is mounted on a fixed frame (28) that supports the conveying device (10).

7. The apparatus according to claim 5 or 6, comprising a pair of cam profiles (27) respectively arranged on both lateral sides of the conveying device (10) in the lateral direction with respect to the longitudinal extending direction of the conveying device (10).

8. The apparatus according to any one of claims 3 to 7, wherein the pressing element (21) includes a surface (21a) having a concave profile intended to be in surface contact with the container (1).

9. The apparatus according to any one of claims 1 to 8, wherein the deforming device (20) is configured to exert a deforming action on the corresponding container (1) associated with the deforming device (20) while the container (1) is being handled along a handling path.

10. Each of the pressing elements (21) of the pair of pressing elements associated with the corresponding container (1) is configured to exert a deforming action including a respective squeezing action, and the two squeezing actions exerted by the pair of pressing elements (21) are carried out substantially simultaneously on both diametrical sides of the container (1) with respect to the container. The apparatus according to any one of claims 3 to 9.

11. A method for testing the airtightness of containers (1) each closed by a membrane (2), comprising: providing a deforming unit (15) including a plurality of deforming devices (20) configured to exert a deforming action on each of a plurality of the containers (1); setting up a detection unit (40) for detecting deformation of the membrane (2) of the container (1) subjected to the deforming action; individually associating each of the deforming devices (20) with a single corresponding container among the plurality of containers (1) in order to exert the deforming action; To test the airtightness of the container (1), a step of detecting the deformation of the membrane (2) of the container subjected to the deformation action; A method comprising.

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