Method and apparatus for ascertaining the presence of cracks in sealed containers

Abstract

A method for ascertaining the presence of cracks in sealed containers includes steps of defining a detection zone (13) in which a sealed container (CT) will be placed, placing a container (CT) in the detection zone (13), ascertaining the presence of a thermal gradient determined by the container in the detection zone (13), the thermal gradient being indicative of the presence of a crack in the container (CT).

Claims

1. A method for ascertaining the presence of cracks in sealed containers, said method comprising the steps of: defining a detection zone (13) adapted to receive a sealed container (CT); placing a container (CT) in said detection zone (13); ascertaining the presence of a thermal gradient determined by said container in the detection zone (13), said thermal gradient being indicative of the presence of a crack in said container (CT); wherein the presence of a thermal gradient is ascertained by a temperature sensor; and wherein a step is provided of putting said detection zone (13) in communication with a temperature sensor (19) through at least one duct (21), and sucking gas from said detection zone (13) through said duct (21) and transferring the gas to the temperature sensor (19) for ascertaining the presence of a thermal gradient caused by the presence of a fluid leakage from said container (CT).

2. The method according to claim 1, wherein a step is provided of maintaining, in said detection zone (13), an atmosphere at a predetermined constant temperature during passage of the container (CT) through said detection zone (13).

3. The method according to claim 1, wherein a step is further provided of submitting said container (CT), when placed in said detection zone (13), to squeezing for promoting possible spillage of fluid from said container (CT) through a crack that may be present in said container.

4. An apparatus for ascertaining the presence of cracks in sealed containers, said apparatus comprising: a detection zone (13) adapted to receive a sealed container (CT); at least one temperature sensor (19) for ascertaining a presence of a thermal gradient determined for said container (CT) in the detection zone (13), said thermal gradient being indicative of a presence of a crack in said container (CT); a duct (21) communicating with said detection zone (13) and said at least temperature sensor (19); and a suction fan (25) communicating with said duct (21) and located downstream of said at least one temperature sensor (19), the suction fan (25) being configured for sucking gas from the detection zone (13) through the duct (21) and transferring the gas to the at least one temperature sensor (19).

5. The apparatus according to claim 4, wherein said detection zone (13) is defined in a detection tunnel (14) equipped with means (16) for maintaining constant temperature of an atmosphere in said detection zone (13).

6. The apparatus according to claim 5, wherein the means for maintaining constant temperature comprises ducts (18) in which a fluid at constant temperature flows, said ducts being located at or near walls (20) of the detection tunnel (14) so as not to hinder passage of the container through the detection zone.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Some preferred embodiments of the invention will be provided by way of non-limiting examples with reference to the accompanying Figures, in which:

(2) FIG. 1 is a schematic representation of a preferred embodiment of the invention;

(3) FIG. 2 is a side perspective view of the apparatus according to a preferred embodiment of the invention;

(4) FIG. 3 is a side perspective view of a detection tunnel incorporated into the apparatus shown in FIG. 1.

(5) In all Figures, the same reference numerals have been used to denote equal or functionally equivalent components.

DESCRIPTION OF A PREFERRED EMBODIMENT

(6) Referring to FIG. 1, there is schematically shown a detection apparatus 11 made in accordance with a preferred embodiment of the invention and including a detection zone 13. Detection zone 13 is arranged to receive a sealed container CT that is to be checked for ascertaining the presence of possible leakages, i.e. of openings capable of putting the content of container CT in communication with the surrounding environment outside the container. In accordance with a preferred embodiment of the invention, detection zone 13 is defined by a supporting structure 15 including a frame 17 and it communicates with the outside environment.

(7) Apparatus 11 further includes a temperature sensor device 19, arranged to generate an electrical signal indicative of the presence of a thermal gradient in a gas mixture passing through or licking said sensor 19. In a particular embodiment of the invention, sensor 19 is a thermistor made of a sintered semiconductor material that, in response to a small temperature variation, exhibits a great resistance variation. The gas mixture to be analysed, when passing through sensor 19, causes an alteration in at least one parameter of an electrical signal passing in an electrical circuit associated with the sensor. The alteration is proportional to the thermal gradient induced by the gas mixture passing through sensor 19. In other embodiments, temperature sensors of different type could be used. Such kinds of sensors are known to the skilled in the art and therefore they will not be described in more detail.

(8) Apparatus 11 further includes a duct 21 communicating with detection zone 13 and with said temperature sensor 19. According to the invention, and as it will become more apparent from the description below, gases flow through duct 21 in the direction shown by arrow f1, from detection zone 13 to sensor 19, in a step of gas suction from said detection zone 13.

(9) In this preferred embodiment of the invention, duct 21 communicates with detection zone 13 through a conveyor 29. According to the invention, a single detection zone 13 could be equipped with a plurality of conveyors 29. For instance, conveyors 29 surrounding container CT passing in zone 13 could be provided, so that substantially the whole of the side surface of container CT passing in zone 13 is submitted to the effect of the air suction by conveyors 29.

(10) Turning back to FIG. 1, a preferred embodiment of the method for detecting leakages from sealed containers according to the invention will be described hereinafter.

(11) The method mainly includes a step in which a container the tightness of which is to be checked is placed in detection zone 13 and a step in which air present in said detection zone 13 is sucked through at least one suction duct 21 communicating with said detection zone 13.

(12) Thus, according to the invention, the method for detecting leakages mainly and preferably includes the steps of: defining a detection zone 13 in which a sealed container will be placed; putting said detection zone 13 in communication with a temperature sensor 19 through a duct 21; placing a container in said detection zone 13; sucking a gas sample from said detection zone 13 through said duct 21 and transferring it to sensor 19 for ascertaining the presence of a gas leakage in said container.

(13) Optionally, the method according to the invention includes a step in which the sample container undergoes a compression or squeezing step, for promoting possible gas spillage. Preferably, said squeezing step is performed by means of a squeezing assembly including rotatable rollers.

(14) Referring to FIG. 2, according to the embodiment of the invention illustrated, a sample container to be tested is placed in detection zone 13, defined in an equipment 10 incorporating apparatus 11 according to the invention, by means of a positioning assembly 51. According to this embodiment, positioning assembly 51 includes a corresponding conveyor belt for the introduction or entrance of the container into detection zone 13 and for the extraction or exit of said container from detection zone 13. Preferably, said positioning assembly 51 further includes a pair of side guides 55a, 55b for correctly positioning the container in detection zone 13, preferably centrally of zone 13.

(15) Referring to FIG. 3, a particular embodiment of the invention is shown in which detection zone 13 is defined inside a corresponding detection tunnel 14. In accordance with this embodiment of the invention, tunnel 14 is equipped with heating and/or cooling means 16 for maintaining constant the temperature in the tunnel in which sample container CT to be tested passes. Said means 16 are arranged to maintain temperature constant and uniform in the whole tunnel, thereby avoiding turbulences or thermal gradients

(16) In the embodiment illustrated, tunnel 14 is equipped with ducts 18 in which a fluid at constant temperature, for instance water, flows. Preferably, ducts 18 are located near or at tunnel walls 20, so as not to hinder the passage of sample CT through detection zone 13 defined inside the same tunnel. Preferably, said ducts 18 can include a single corresponding pipe defining a winding path extending over a great part or the major part of the surface of walls 20 of tunnel 18 surrounding detection zone 13.

(17) Always in accordance with the invention, entrance opening 22 for sample product CT is preferably occupied by an air curtain or blade distributed on a plane substantially perpendicular to the advance direction of the sample product passing through detection zone 13.

INDUSTRIAL APPLICABILITY

(18) The invention finds industrial application in several fields, for detecting leaks and micro-leaks from containers of substantially any kind, either compressible or rigid. The invention can also be applied for detecting leakages of liquids, for instance water or beverages, from pressurised rigid containers.

(19) The invention as described and illustrated can undergo several variants and modifications all falling within the same inventive principle.