Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/36—Investigating fluid-tightness of structures by using fluid or vacuum by detecting change in dimensions of the structure being tested
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors

Definitions

• the present invention departs from a technique of manufacturing unleaky containers as disclosed in the WO 00/073760 or US patent 6 557 395, 6 439 032 or 6 840 087 all of the same applicant as the present invention.
• the present invention is a manufacturing method wherein after having provided a closed container, at least one a biasing member is moved towards and onto one of the first and second flexible wall areas of the container. Such biasing moving is stopped. A biasing force on the container is monitored and the biasing force as monitored is sampled resulting in a first force measuring signal at a first point in time. The addressed biasing force as monitored is further sampled at least at one second subsequent point in time which results in a second force measuring signal. A difference signal is generated in dependency of the first and second force measuring signals. The addressed container is considered unleaky if the difference signal fulfils a test criterium. Thereby the biasing member is moved towards and onto the first flexible wall area of the container and monitoring the biasing force is performed at the second flexible area. Sampling of the biasing force monitored which results in the addressed first force measuring signal comprises
• BESTATIGUNGSKOPIE determining a maximum force signal value having occurred during a time span up to and including the first point in time.
• the biasing member is moved up to a predetermined position with respect to the container which is in one embodiment defined by a mechanical stop. Further in one embodiment stopping of the biasing member is performed at least substantially at the first point in time thus at least substantially at that moment at which sampling of the biasing force monitored results in the first force measuring signal.
• a predetermined time span is selected and the maximum force value having occurred during this predetermined time span up to and including the first point in time is determined.
• biasing comprises moving at least two biasing members towards and onto the first flexible wall area from opposite sides of the container.
• first flexible wall area of the container is a wall area of a body of the container and the second flexible wall area is a sealing cover of an opening of the container body.
• second flexible area is a foil-like sealing cover of the addressed opening.
• monitoring the biasing force at the second flexible wall area is performed along a force sensing surface which is spaced from the second flexible area by a predetermined amount said second flexible wall area being thereby considered at unbiased condition of the container.
• This predetermined amount is substantially smaller than a maximum distance which the second flexible wall area may at all bow outwards due to an increased pressure in the closed container.
• monitoring the biasing force comprises monitoring by means of a resistance gouge.
• the biasing force as monitored is compared at a third point in time previous to said first point in time with a threshold value and a container is established as having a large leak if the force monitored does not at least reach the threshold value .
• a multitude of containers is provided, moving on a conveyor and moving the biasing members, stopping same, monitoring the biasing force, performing the addressed samplings, generating the difference signal and further performing the addressed leaky/unleaky consideration is performed on more than one of the moved containers on the conveyor at least substantially simultaniously.
• the force monitored is compared at a third point in time previous to the first point in time with a threshold value and there is established a container as having no large leak if the force as monitored at the third point in time at least reaches the threshold value.
• the force value monitored at the addressed third point in time if the threshold value is at least reached is averaged with such force values generated at previously tested containers which have been considered as having no large leak and the threshold value is applied in dependency of a result of such averaging.
• the difference signal is compared with a small-leakage-indicative threshold value.
• the difference signal is averaged with such difference signals which have been generated during previous testing of containers having being considered as unleaky, whereby the small-leakage- indicative threshold value is controlled in dependency of the result of such averaging.
• At least one force threshold value and the force monitored is compared with such threshold value whereby the addressed threshold value is updated as a function of comparing result .
• the output of the addressed force detector is operationally connected to a storing unit, the output of which being operationally connected to one input of a comparator unit, the second input thereof being operationally connected to the output of the force detector.
• the biasing arrangement is positioned so as to bias the first flexible area of the container and the force detector is positioned to cooperate with the second flexible area of the container.
• the biasing arrangement comprises at least two relatively movable biasing members relatively movable in a plane.
• the force detector has a force sensing surface which detects forces substantially perpendicular to the addressed plane.
• the force detector comprises a resistance gauge.
• the biasing arrangement cooperates with a mechanical stop limiting its biasing action upon the container.
• the output of the force detector is operationally connected to an input of a maximum value detecting unit.
• the apparatus comprises a conveyor arrangement for a multitude of the addressed containers. At least two of the addressed biasing arrangement and force detector are provided moving with the conveyor.
• a method for manufacturing unleaky closed containers with a first and a second flexible wall area of different flexibility characteristics wherein a closed container is provided and at least one biasing member is moved relatively towards and onto one of the flexible areas of the container. The addressed moving is stopped. The biasing force on said container is monitored. The biasing force as monitored is sampled which results in a first force measuring signal at a first point in time. The biasing force monitored is sampled at least at one second subsequent point in time which results in a second force measuring signal. A difference signal is generated in dependency of the first and the second force measuring signals as a leak indicative signal.
• An average signal of difference signal as generated during previous testing of containers is updated with the actual difference signal, if the container actually under test is unleaky.
• the difference signal is thereby compared with at least one threshold signal which threshold signal is controlled in dependency of the addressed average signal.
• moving the biasing member is performed relatively towards and onto the first flexible wall area and monitoring the biasing force is performed on the second flexible wall area.
• Sampling the biasing force monitored which results in the first force measuring signal comprises determining a maximum force signal value which has occurred during a time span up to and including the first point in time.
• a closed container is provided and at least one biasing member is moved relatively towards and onto one of said flexible wall areas of the container.
• the moving is stopped.
• a biasing force on the container is monitored.
• the biasing force as monitored is sampled which results in a first force measuring signal at a first point in time.
• the biasing force monitored is further sampled at least at one second subsequent point in time which results in a second force measuring signal.
• a difference signal is generated in dependency of the first and second force measuring signals as one leak indicative signal.
• the biasing force as monitored is further sampled at a further point in time resulting in an actual further force measuring signal which is leak indicatif.
• An average signal of further force measuring signals is generated during preceeding testing of unleaky containers and such averaged signal is updated with the actual further force measuring signal if the actual further force measuring signal indicates a unleaky container.
• the difference signal is thereby compared with a thresehold value which depends from the addressed average signal. A container which is indicated as leaky is rejected.
• Sampling of the biasing force as monitored which results in the first force measuring signal comprises determining a maximum force signal value having occurred .during a time span up to and including the first point in time .
• a method for manufacturing closed containers with a flexible wall portion wherein a closed container is provided and is biased.
• a biasing force on the container is monitored and from such force as monitored a maximum force value as occurring during a time span is detected.
• a signal which depends on the addressed maximum force value as detected is stored and compared with a signal dependent on the biasing force as monitored. The container is rejected as leaky in dependency of a result of the addressed comparing.
• FIG.l schematically and simplified a closed container being leak tested in the frame of manufacturing such containers being unleaky and according to the present invention
• Fig.2 an enlarged area of the representation according to fig. 1 showing biasing force monitoring at one of the flexible areas of the container's wall according to fig. 1;
• Fig. 3 qualitatively different force versus time characteristics at containers tested with an apparatus according to the present invention and by a testing procedure in the frame of the manufacturing method according to the present invention;
• Fig. 4 a simplified signal flow/functional block diagram of an apparatus according to the present invention operating according to the leak testing procedure within the frame of the manufacturing method according to the present invention
• Fig. 5 an embodiment for accurately performing digital signal comparison as applicable at the apparatus according to fig. 4;
• Fig. 6 different courses of force dependent signals over time as encountered at equally unleaky equal containers and as caused e.g. by manufacturing tolerances or varying environmental parameters;
• Fig. 7 an embodiment for generating a time varying threshold value for large leak detection
• Fig. 8 qualitatively courses of time varying reference and threshold value signals as exploited in some embodiments of the present invention
• Fig. 9 by means of a simplified functional block diagram evaluating from a leak indicative signal whether a container under test has a small leak or not;
• Fig. 10 for an embodiment of the present invention generating a time varying threshold value for a small leak indication;
• FIG. 11 in a simplified and schematic representation, an inline leak testing apparatus according to the present invention for high-rate container testing as applied in the frame of the manufacturing method according to the present invention, finally selecting only unleaky containers out of a stream of closed containers;
• FIG. 1 shows schematically the principal according tothe present invention.
• the opening 4 of container 1 is sealingly closed by a sealing foil-like member, which is a second flexible area 3b of the container's wall 3.
• the areas 3a and 3b are of different flexible characteristic.
• the container 1 is a bottle the bottle wall 3c of which being of a plastic material the opening of which being sealed with a foil-like cover 4 which is sealed to the border of the opening 4 of bottle wall 3c e.g. by welding.
• the foillike cover is on one hand and as was addressed flexible but substantially non-elastic as made of a metalized plastic foil or a plastified metal foil as of aluminum.
• the first flexible area 3a of bottle-wall 3c is of thicker plastic material and is more elastic.
• the addressed first and second areas 3a, 3b of the overall container's wall 3 are of different flexibility characteristics.
• the container 1 is positioned between two biasing members 5a and 5b of a biasing arrangement 5.
• the biasing members 5a and 5b are relatively moved towards and from each others to provide a biasing load B on the first flexible area 3a.
• both members 5a and 5b are equally moved towards and from each others and with respect to a mechanic machine reference 6 e.g. a conveyor for the container 1.
• a mechanic machine reference 6 e.g. a conveyor for the container 1.
• the second flexible area 3b formed by the sealing foil-like member is bowing outwards as also shown in fig. 1 and, in an enlarged representation, in fig. 2.
• the outwards bowing second flexible area 3b is thereby pressed against the sensing surface 9 a of a force detector 9 which is stationary with respect to the mechanical reference 6 of the testing machine.
• the distance d between the second flexible wall portion 3b formed by the sealing foil-like member and the sensing surface 9a of the force detector 9 is selected much smaller than the maximum distance D the foil-like member may bow outwards due to an increased pressure inside the container 1; in this respect fig. 2 does not show the correct relation of d and D.
• the spacing d is selected e.g. to be 0.5 mm.
• the effect of selecting the spacing d small is that bowing outwards of the second flexible area 3b is limited to such an extent that the sealing link or weld 5 is substantially not mechanically loaded by tensile strength by the outwards bowing.
• the relative movement of the biasing members 5a and 5b to squeeze first flexible area 3a is generated by respective drives 7a and 7b and is limited by respective stops 8a and 8b.
• fig. 3 a qualitative force versus time diagram explaining the inventive method as performed by the inventive apparatus, is shown. At times 0 according to fig. 3 the biasing movement of the two biasing members 5a and 5b is initiated. Because the characteristic of movement i.e. acceleration and thus speed as generated by the drives 7a and 7b upon the biasing members 5a and 5b is known the time span for moving the biasing members 5a and 5b up to the stops 8a and 8b of fig. 1 is known and shown in fig. 3 by the time span up to tl.
• the maximum value of force as monitored by the force detector 9 up to ti is determined.
• the movement characteristic of the drives 7a and 7b and positioning of the stops 8a and 8b is selected so that the course F(t) as monitored by force detector 9 will reach a maximum value within the time span up to t .
• three positive types of courses F(t) are shown as (ai) , (a 2 ) and (a 3 ) . If the course substantially accords with (ai) there is thus determined by maximum value detection up to ti the value F max ⁇ .
• FIG. 4 the inventive apparatus in its principal form which performs the procedure as explained with the help of fig. 3 is schematically shown.
• the container 1 to be tested is positioned between the biasing members 5a and 5b which are driven by drives 7a and 7b.
• the stops 8a, 8b which have been explained in context with fig. 1 are not shown in this figure.
• a timing unit 17 initiates the biasing movement B of the biasing members 5a and 5b and thereby establishes with an eye on fig. 3 for the zero time 0.
• the force depending electrical output signal S(F) of force detector 9 is fed at predetermined time t Tj , controlled by the timing unit 17 as schematically shown and by switching unit SWl to a comparator unit 21.
• the output signal S(F) is compared with a large leak indicative threshold value S 0 (F LL ) as generated by unit 23.
• switching unit SW 2 the input thereof being operationally connected to S(F) is opened disabling, via a control unit 25 further biasing of container 1 by the biasing members 5a and 5b.
• signal S(F) is led via SW 2 to a storing unit 26 which is enabled during the time span M up to the moment ti of fig. 3 so as to store the values of the electric signal S(F) representing the relevant part of the characteristics F(t) as monitored by detector 9.
• the stored content of the storing unit 26 representing a part of the course F(t) up to ti is fed to a maximum detection and storing unit 27 wherein the signal S(F max ) is detected and stored which signal defines for the maximum force F max which has been detected by force detector 9 up to the moment ti.
• the sensing surface 9a is, as schematically shown in fig. 2 provided with a surface structure 19 which may be realized by roughening this surface to a predetermined amount. It is perfectly clear that also the contact surfaces of the biasing members 5a and 5b as well as the surface whereupon container 1 resides may be structured to avoid also there clogging of possibly present leaks. Instead of evaluating directly the output signal OUT ( ⁇ F) of comparator unit 28 it is possible to control biasing by means of the biasing members 5a and 5b as a function of this output signal thereby removing the stops 8a and 8b as of fig. 1.
• a negative feedback control loop is installed (not shown) wherein the comparator unit 28 compares a rated value according to the detected and stored maximum force signal S(F max ) from unit 27 with an instantaneously prevailing signal S(F) and applying as an adjusting unit in the negative feedback control loop the drives 7a and 7b operating the biasing members 5a and 5b so as to minimize the output signal OUT ( ⁇ F) of comparator unit 28.
• the control signal applied to the drives 7a and 7b is exploited as a leak indicative signal.
• comparator unit 28 In fig. 5 one realization form of comparator unit 28 is schematically shown. As was addressed above memorizing the relevant part of the force versus time representing signal S(F) as in unit 26 and determining therefrom the maximum value S(F max ) is in one embodiment performed digitally. To do so according to fig. 4 there is installed upstream unit 26 an analogue to digital conversion unit as shown in dash lines. According to fig. 5 the detected digital signal S(F max ) # is fed to one input of a difference forming unit 123 # . As schematically shown in fig. 5 e.g. at the time ti or later the same stored digital signal S(F max ) # is fed also to the second input of difference forming unit 123 # .
• the output of the difference forming unit 123 # should be zero. If this output signal deviates from zero it is considered as an offset signal and is stored in a storing unit 127 # and applied for compensation purposes to the difference forming unit 123 # e.g. and as shown in fig. 5 via an adding unit 128 # upstream one of the inputs of difference forming unit 123 # .
• the force values measured at these unleaky containers 1 are slightly different and define a statistic distribution. There results an average value (RFLL) m .
• the threshold value So(F TjL ) of fig. 4 is found by substracting from the value (RFLL) m an offset value ⁇ RFLL the magnitude of which being selected according to the allowed probability that a container which has in fact no large leak is treated as a container having such large leak.
• the threshold value S 0 (F LL ) of fig. 4 is established in one embodiment and with an eye on fig. 6 by the value (RFLL) m - ⁇ RFLL.
• the average result signal S(F) accords with the time varying value (RFLL) m of fig.6. From the output average result S(F) the offset ⁇ RFLL is subtracted and the result of this operation is a dynamically varying reference value applied as S 0 (F LL ) to unit 21 according to fig. 4.
• This dynamically varying reference value So(F LL ) of fig. 4 is shown in fig. 8 qualitatively starting from an initial setting as e.g. found, as was addressed, with the help of measurements at test containers 1 without large leak.
• the output signal OUT ( ⁇ F) is further evaluated by being fed to a comparator unit 125 which is enabled at or after the time t 2 .
• a reference value source 130 a reference value ⁇ SLREF is fed to comparator unit 125.
• the value of ⁇ SLREF may controllably be varied in time and/or a reference value ⁇ R to which ⁇ SLREF is referred to, may also controllably be varied in time.
• a signal SL is generated at unit 125 indicating the presence of a small leak SL in the container 1 under test. If the signal OUT ( ⁇ F) does not reach ⁇ SLREF then the container is considered unleaky as neither a large leak LL nor a small leak SL has been detected.
• the average signal S(F) (tj ) is also the basis for referring ⁇ SLREF of fig. 9 to.
• the reference value ⁇ SLREF is not referred to a static value but is referred to S(F) (t LL ) , as generated at the output of averaging unit 130 of fig.7.
• a multitude of testing stations 140 are moved with a conveyor arrangement 142 for containers 1 to be tested. During the conveying course of the containers 1 they are brought into the testing stations 140 which keep moving with the conveyor arrangement 142.
• Each testing unit 140 is construed as has been explained.
• the respective squeezing biasing members 5a and 5b at each testing station are shown as well as the force detectors 9. Without interruption of conveying and the containers 1 become biasingly squeezed by the biasing members 5a and 5b and the resulting force on the respective force detector 9 is evaluated.
• a container If a container is detected to be leaky it is separated from the unleaky containers as schematically shown by selecting switch 144 resulting in a train of containers 1 UL which are unleaky.
• the result of container testing is the manufacture of unleaky containers 1 UL .
• force detector 9 different known detectors as e.g. Piezzo detectors may be used.
• the force detector 9 includes a resistance strain gauge sensor as e.g. of the type Z6 as manufactured by Hottinger Baldwin Messtechnik GmbH, Germany.

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• Examining Or Testing Airtightness (AREA)

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• 2005
  • 2005-09-09 EP EP05777631A patent/EP1922536A2/de not_active Withdrawn
  • 2005-09-09 AU AU2005255063A patent/AU2005255063B2/en not_active Ceased
  • 2005-09-09 RU RU2009124045/28A patent/RU2492440C2/ru not_active IP Right Cessation
  • 2005-09-09 JP JP2008529441A patent/JP4824089B2/ja not_active Expired - Fee Related
  • 2005-09-09 WO PCT/CH2005/000538 patent/WO2005124308A2/en not_active Ceased
  • 2005-09-09 EP EP13172969.1A patent/EP2642269A3/de not_active Withdrawn
  • 2005-09-09 KR KR1020137015906A patent/KR20130083931A/ko not_active Ceased
  • 2005-09-09 CN CN2005800514983A patent/CN101258395B/zh not_active Expired - Fee Related

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