Leakage test with blocking device

Description

[0001] The invention relates to the leak test on a test specimen.

[0002] To test the leak tightness of test specimens, such as food packaging, it is common practice to place the specimen to be tested in a test chamber and evacuate the chamber to a pressure lower than the pressure inside the specimen. The pressure inside the specimen is typically atmospheric. The test chamber is evacuated using a vacuum pump.

[0003] After evacuating the test chamber, gas escaping from the test object into the test chamber can be detected using a gas detector or gas analyzer. The measurement of a predetermined amount of test gas indicates that the test object has a leak through which the test gas is escaping from the interior of the test object into the test chamber and reaching the gas detector. Alternatively or additionally, the pressure inside the test chamber can be monitored. An increase in the pressure inside the test chamber above a predetermined value or at a predetermined rate indicates that the test object has a leak through which gas is escaping from the interior of the test object into the test chamber, increasing the pressure there.

[0004] Typically, a large number of test specimens are tested for leaks one after the other, with an operator placing the specimens into the test chamber, closing the test chamber, starting and monitoring the leak test, and then removing the specimens after the leak test has been completed. There is a risk that a test specimen identified as leaking will be assigned to the group of previously identified leak-tight specimens and not separated from them.

[0005] EP 0 931 253 B1 describes a device for testing the tightness of packaging.

[0006] US 2010 / 0326173 A1 describes a method and apparatus for testing filled and sealed containers.

[0007] The invention is based on the object of enabling an improved leak test.

[0008] The method according to the invention is defined by the features of patent claim 1. The leak testing device according to the invention is defined by the features of patent claim 12.

[0009] According to the invention, the test chamber is blocked depending on the result of the leak test in order to prevent the test specimen from being removed from the test chamber if the result of the leak test indicates a leak in the test specimen, while in the case of a leak-tight test specimen the test chamber is released. This prevents the operator removing the test specimens from the test chamber from treating a test specimen identified as leaking as a leak-tight test specimen and removing it from the test chamber and inadvertently assigning it to the group of test specimens previously tested as leak-tight. Because the test chamber is blocked in the case of a leaking test specimen, the operator must first perform further activities in order to remove the test specimen from the test chamber. The process is therefore different for a leaking test specimen than for a leak-tight test specimen and the risk of confusion by the operator is reduced.

[0010] Before the leak test, the test chamber containing the test specimen can be evacuated to a vacuum pressure that is lower than the pressure inside the test specimen. For this purpose, the test chamber can be connected to a vacuum pump. In the event of a leak in the test specimen, gas from inside the test specimen escapes through the leak into the vacuum chamber.

[0011] Alternatively, the test specimen can be pressurized and exposed to at least a portion of a specific test gas. This test specimen is placed in a test chamber in the form of an accumulation chamber, in which the test gas concentration is measured. The test gas concentration in the accumulation chamber, which increases over time, is a measure of the leak rate in the test specimen.

[0012] The test chamber can be blocked automatically depending on the leak test result. The leak test result is the measurement result obtained with a leak test device, which can be a gas detector, a gas analyzer, and / or a gas pressure gauge.

[0013] To unlock or unblock the test chamber, a key is preferably required, which can be used by a human operator to unlock the test chamber. The key can be an electronic key, for example, in the form of a password or token, or a mechanical key.

[0014] The test chamber can be blocked using a blocking device operated by a control device, which receives information about the leak test from a leak detector. A leak detector is understood to be a measuring device that performs the leak test, such as a gas detector, a gas analyzer (e.g., a mass spectrometer or an infrared absorption analyzer), or a gas pressure gauge.

[0015] Blocking the test chamber can be achieved alternatively or additionally by applying or maintaining a vacuum inside the test chamber. In this embodiment, the blocking device can be understood as the control electronics that applies or maintains the vacuum, for example, by activating a vacuum pump or maintaining its operation.

[0016] The test chamber can be blocked by applying a mechanical force. This force can be a force that counteracts the force applied to open the test chamber. The force can be applied by a vacuum inside the test chamber or by a mechanical locking element, such as a lock or latch.

[0017] The measurement signal of the leak tester can be transmitted as an electronic signal to a control device which is electronically connected to the blocking device, wherein in the case of a test object being detected as leaking, the control device transmits a control signal to the blocking device which triggers an actuation of the blocking device in order to block the test chamber.

[0018] In the present case, a test specimen in which no leak was detected is referred to as tight, whereas a test specimen in which a leak was detected is referred to as leaking. For this purpose, the measurement signal from the leak tester is typically compared with reference values ​​and / or a threshold value in order to be able to automatically assess, based on the measurement signal, whether the test specimen should be assigned to the group of tight test specimens or the group of leaking test specimens. A human operator carrying out the leak test will typically assign a test specimen that was tested to be tight to a group of tight test specimens by removing the test specimen from the test chamber, for example, and moving it to a container provided for this purpose, onto a conveyor belt provided for this purpose, or another spatially defined area. The invention is intended to reduce the risk of the human operator inadvertently assigning a test specimen identified as leaking to the group of tight test specimens.Blocking the test chamber results in a process for the operator that differs from that for leak-tight test specimens. Blocking the test chamber during removal of the test specimen provides the operator with an additional opportunity to identify that the test specimen has been tested as leaky and should not be assigned to the group of leak-tight test specimens.

[0019] An embodiment of the invention is explained in more detail with reference to the figure. The figure shows a block diagram of the leak testing device according to the invention.

[0020] A test specimen 12 to be tested for leaks is placed inside a test chamber 14. The test chamber 14 is a conventional vacuum chamber and is shown in the figure in a sealed state. A vacuum pump 18 is connected to the test chamber 14 by vacuum technology in order to evacuate it to a pressure that is lower than the pressure inside the test specimen 12. In the event of a leak in the test specimen 12, test gas will escape from the interior of the test specimen 12 into the interior of the test chamber 14 in the area outside the test specimen 12.

[0021] A leak tester 16 is also connected to the interior of the test chamber 14 via a vacuum-conducting gas line for leak testing. In the illustrated embodiment, the leak tester 16 is contained in the gas line connecting the test chamber 14 to the vacuum pump 18. Other configurations are conceivable. The leak tester 16 can be a conventional gas detector, a gas analyzer, or a pressure gauge to monitor the pressure inside the test chamber 14. Valves required for the leak test are present but are not shown in the figure for reasons of simplicity.

[0022] As soon as the leak tester 16 measures test gas that has escaped from the interior of the test piece 12 or, in the case of a pressure measuring device, measures a pressure increase that indicates a leak in the test piece 12, the leak tester 16 sends an electronic signal to a control device 22 that is electronically connected to the leak tester 16. The control device 22 is designed to automatically generate a control signal in the event of a measurement signal from the leak tester 16 that indicates a leaky test piece 12, which activates a blocking device 20 to prevent the test chamber 14 from opening. For this purpose, the control device 22 is electronically connected to the blocking device 20. The blocking device 20 can be a mechanical lock or a lock that locks the test chamber 14.Alternatively or additionally, the blocking device 20 can also be a valve that connects the interior of the test chamber 14 with the atmosphere surrounding the test chamber 14 and that is opened before the test chamber 14 is opened to ventilate the test chamber 14. To block the test chamber 14, the valve remains closed, thus preventing ventilation of the test chamber 14. The vacuum pressure prevailing inside the test chamber is then so great that a human operator cannot open the test chamber 14. The closing force for closing the test chamber is then generated by the vacuum pressure. Alternatively or additionally, the closing force can be applied as a mechanical force by a closing device.

[0023] Furthermore, it is conceivable that the control device 22 activates the vacuum pump 18 or an additional vacuum pump or continues to operate it in order to maintain or even increase the vacuum pressure inside the test chamber 14. In this case, the blocking device 20 could be understood as part of the vacuum pump or as an additional vacuum pump.

[0024] If an operator now wishes to remove the test specimen 12 from the test chamber 14 after the leak test has shown that the test specimen 12 has a leak, the operator must use a key to deactivate the blocking device 20. The key can, for example, be a mechanical key to unlock a mechanical locking device or to command the control device 22 to deactivate the blocking device 20. The key can also be an electronic key in the form of a password that the user must enter into an operating terminal of the control device 22. In any case, the operator who wishes to remove the test specimen 12 from the test chamber 14 must perform an additional action to remove a leaking test specimen from the test chamber 14 than in the case of a leak-tight test specimen.This reduces the risk of confusing a leaky test specimen with the group or set of test specimens previously tested as leak-tight.

Claims

1. A method for leak testing of a test specimen (12), comprising the following steps: placing the test specimen (12) in a test chamber (14), testing the leak-tightness of the test specimen (12) in the test chamber (14), opening the test chamber (14) and removing the test specimen (12) if the leak test has determined that the test specimen (12) is leak-tight, characterized in that opening the test chamber (14) is blocked in order to prevent removal of the test specimen (12) if the leak test has determined a leak in the test specimen.

2. The method according to claim 1, characterized in that the test chamber (14) is automatically blocked depending on the result of the leak test.

3. The method according to claim 1 or 2, characterized in that an electronic or mechanical key is required to release the blocking.

4. The method according to any one of the preceding claims, characterized in that the test chamber is blocked with the aid of a blocking device (20) actuated by a control device (22), the control device (22) receiving information about the leak test from a measuring device (16) carrying out the leak test.

5. The method according to any one of the preceding claims, characterized in that the test chamber (14) is blocked by applying or holding a vacuum inside the test chamber (14).

6. The method according to any one of the preceding claims, characterized in that the test chamber (14) is blocked by applying a mechanical force.

7. The method according to claim 6, characterized in that the mechanical force is applied by the blocking device (20).

8. The method according to claim 7, characterized in that the blocking device (20) is a mechanical closing device.

9. The method according to any one of the preceding claims, characterized in that the test chamber (14) containing the test specimen (12) is evacuated to a test chamber internal pressure which is lower than the pressure inside the test specimen for testing the leak-tightness of the test specimen, in order to detect gas entering the test chamber from a leak in the test specimen.

10. The method according to any one of claims 1-8, characterized in that the pressure inside the test specimen (12) for testing the leak-tightness of the test specimen is increased to a pressure which is higher than the pressure inside the test chamber, in order to detect gas entering the test chamber from a leak in the test specimen according to the accumulation principle.

11. The method according to any one of the preceding claims, characterized in that the step of testing the leak-tightness of the test specimen (12) is carried out with the aid of a measuring device (16) in the form of a pressure measuring device or a gas detector or a gas analyzer, the measuring signal of the measuring device (16) being transmitted to a blocking device (20) actuating the control device (22).

12. A leak testing device for testing the leak-tightness of a test specimen (12), comprising a test chamber (14) receiving the test specimen (12), a leak detector (16) connected to the test chamber (14), characterized in that a blocking device (20) is configured to block the test chamber (14) in order to prevent removal of the test specimen (12) if the measuring signal of the leak detector (16) corresponds to a leaking test specimen (12), and to enable the test chamber (14) to be opened if the measuring signal corresponds to a non-leaking test specimen.

13. The leak testing device according to claim 12, characterized by vacuum pump (18) connected to the test chamber (14) in order to evacuate the test chamber.