JP2013024634A - Leak testing method, and leak testing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten time for leak testing.SOLUTION: A leak testing method includes: a step of measuring a temperature correction value, for measuring a change of differential pressure measured between pressures inside a master vessel and a work vessel, as the temperature correction value, in a state where the master vessel and the work vessel are blocked by use of air pressure; a step of measuring a test differential-pressure change, for measuring the change of the differential pressure, as a test differential-pressure value, in a state where the master vessel and the work vessel are blocked by use of test pressure other than the air pressure; and a temperature correction measuring mode step for correcting the test differential-pressure value on the basis of the temperature correction value, and determining whether a leak exists or not in the work vessel on the basis of the corrected test differential-pressure value. Further, when the change of the differential pressure that is measured in the step of measuring the temperature correction value, does not exceed a first reference value in the temperature correction measuring mode step, the method performs the step of measuring the test differential-pressure change, and shifts to a pressure measuring mode step for determining whether the leak exists or not in the work vessel on the basis of the test differential-pressure value measured in the step of measuring the test differential-pressure change. Thereafter, if the leak is determined to exist in the pressure measuring mode step, the method returns to the temperature correction measuring mode step.

Description

  The present invention relates to a leak test method and a leak test apparatus, and more particularly to a leak test method and a leak test apparatus for detecting the presence or absence (airtight state) of a work container based on a pressure difference (differential pressure) between a master container and a work container. About.

  A leak test is performed to check the air tightness of work containers to be inspected such as pipes and containers. The principle of the leak test is to check whether the internal pressure of the work container changes after the internal pressure of the work container is increased or decreased from the external pressure (usually atmospheric pressure). When the internal pressure of the work container changes, it means that a leak has occurred in the work container, which means that the airtightness is defective.

  In this leak test method, it has been proposed to measure the change in the internal pressure of the work container with a single pressure sensor and determine whether there is a leak based on the change in the pressure. For example, Japanese Patent Application Laid-Open No. H10-260628. In this leak test method, in order to distinguish whether the change in internal pressure after pressurization or depressurization of the work container has changed due to a leak or a temperature change due to a temperature difference from the outside air temperature, the inside of the work container is Measure the change in the internal pressure with the same atmospheric pressure condition as in the case of eliminating leaks, measure the change in the internal pressure due to temperature change, and change the internal pressure of the work container after pressurization or decompression By removing the internal pressure change due to the temperature change in the atmospheric pressure state, the effect of the temperature change is eliminated, that is, the temperature test is performed to perform the leak test.

  On the other hand, it has been proposed to measure a differential pressure between a reference master container and a work container to be inspected, and to perform a leak test based on whether there is a change in the differential pressure after pressurization or depressurization. For example, Patent Documents 2 and 3. In the case of a differential pressure sensor that measures the internal pressure difference between the master container and the work container, the pressure measurement range can be narrower than that of a single pressure pressure sensor that measures the internal pressure of the work container. The pressure change can be measured with high accuracy by increasing the resolution.

  In this differential pressure type leak test, in order to remove the influence of the change in internal pressure accompanying the change in temperature of the work container from the change in the differential pressure between the master container and the work container after pressurization or depressurization, It has been proposed to close a work container in an atmospheric pressure state, measure a change in differential pressure due to a temperature change as a correction value, and remove the correction value from a change in differential pressure in a pressurized or reduced pressure state.

Japanese Patent No. 3484253 Japanese Patent No. 3411374 Japanese Patent No. 3133275

  In the above-described differential pressure type leak test, a temperature correction value measuring process for measuring a differential pressure change in an atmospheric pressure state and a differential pressure change measuring process for measuring a differential pressure change in a pressurized or depressurized test pressure state are performed. By doing so, the effect of temperature change is excluded.

  However, repeating the temperature correction value measurement process in the atmospheric pressure state and the test differential pressure change measurement process in the test pressure state for each work container increases the time required for the test process and increases the leak test cost. Invite.

  Therefore, an object of the present invention is to provide a leak test method and a leak test apparatus that can shorten the time of the leak test process.

According to the first aspect of the leak test method,
A temperature correction value measuring step for measuring a change in the differential pressure between the internal pressure of the master container and the work container as a temperature correction value in a state where the master container and the work container are closed at atmospheric pressure, and the master container and the work container. A test differential pressure change measuring step of measuring a change in the differential pressure as a test differential pressure value in a state of being blocked with a test pressure other than the atmospheric pressure, and correcting the test differential pressure value based on the temperature correction value. , Performing a temperature correction measurement mode step of determining whether or not the work container has leaked based on the corrected test differential pressure value,
When the change in differential pressure measured in the temperature correction value measurement step in the temperature correction measurement mode step does not exceed the first reference value, the test differential pressure change measurement step is performed and measured in the test differential pressure change measurement step. The process proceeds to a pressure measurement mode process for determining whether or not there is a leak in the work container based on the test differential pressure value.
When it is determined that there is a leak in the pressure measurement mode process, the process returns to the temperature correction measurement mode process.

  According to the first aspect, when the change in the differential pressure measured in the temperature correction value measurement process in the temperature correction measurement mode process does not exceed the first reference value, the test differential pressure change measurement process is performed and the test difference is measured. Shifts to the pressure measurement mode process that determines whether there is a leak in the work container based on the pressure value, and repeats the pressure measurement mode process as long as the determination of no leakage continues, and temperature correction measurement is performed when it is determined that there is a leak Since the mode is returned to the mode, the temperature correction value measurement process is omitted at least in the pressure measurement mode process to shorten the test time, while the erroneous inspection in the pressure measurement mode process can be prevented.

It is a figure which shows an example of the apparatuses used with the leak test method in this Embodiment. It is a figure which shows the example of a change of a differential pressure in the state which obstruct | occluded the master container and the workpiece | work container in the test differential pressure change measurement process with the test pressure. It is a figure which shows the example of a change of a differential pressure in the state which obstruct | occluded the master container and the workpiece | work container in the test differential pressure change measurement process with the test pressure. It is a figure which shows the example of the temperature correction measurement mode in the differential pressure type leak test in this Embodiment. It is a figure which shows the example of the temperature correction measurement mode in the differential pressure type leak test in this Embodiment. It is a figure which shows the example of the temperature correction measurement mode in the differential pressure type leak test in this Embodiment. It is a figure which shows the example of the temperature correction measurement mode in the differential pressure type leak test in this Embodiment. It is a figure which shows the temperature correction measurement mode in this Embodiment. It is a figure which shows the pressure measurement mode in this Embodiment. It is a state transition diagram of temperature correction measurement mode S11 and pressure measurement mode S14 in the leak test in this Embodiment. It is a figure which shows an example of the leak test by FIG. It is a figure which shows the example which a misjudgment generate | occur | produces in a leak test. It is an operation | movement flowchart figure of the leak test apparatus in this Embodiment. It is a flowchart figure of the modification 1 of operation | movement of the leak test apparatus in this Embodiment. It is a flowchart figure of the modification 2 of operation | movement of the leak test apparatus in this Embodiment.

  FIG. 1 is a diagram illustrating an example of devices used in the leak test method according to the present embodiment. In the leak test, the work container WA to be subjected to the leak test and the master container MA serving as a reference container of the same shape or different size but the same shape as the work container are connected to the branch pipes 3 and 2 via connecting devices (not shown). Can be attached to each. The branch pipes 2 and 3 are respectively provided with valves MV and WV that can be opened and closed, and a differential pressure sensor 4 that detects a differential pressure between the internal pressures of the master container and the work container.

  Further, a pressure pump for applying a test pressure can be connected to the common pipe 1 connected to the branch pipes 2 and 3, and a valve PV and a pressure regulator RG that can be opened and closed are provided. Further, the branch pipes 2 and 3 are provided with a valve AV for opening to atmospheric pressure.

  The leak test apparatus 10 is connected to the pressure sensor 4, the valves MV, WV, PV, AV, and the pressure pump 5, and a control device including a built-in microcomputer executes a leak test program, and the valves MV, WV, PV, AV, and an actuator such as the pressure pump 5 are appropriately driven, the detection value of the pressure sensor 4 is acquired, and a leak test of the work container WA is performed.

  In FIG. 1, the atmospheric pressure adjusting means for closing the master container MA and the work container WA in the atmospheric pressure state includes a master container side valve MV, a work container side valve WV, and a valve AV opened to the atmospheric pressure. The On the other hand, the test pressure adjusting means for closing the master container and the work container with a test pressure other than the atmospheric pressure includes the master container side and the work container side valves MV and WV, the pressure pump 5, the pressure regulator RG, and the valve PV. Is done.

  Work containers include not only containers but also pipes and other sealed structures that have a volume that can accommodate gases and liquids and that require leak inspection. Further, the test pressure applied to the master container or the work container by the pressure pump 5 may be either a pressure increased or reduced from the atmospheric pressure. However, in the following description of the embodiment, pressurization will be described as an example of the test pressure.

[Principle of differential pressure type leak test]
2 and 3 are diagrams showing examples of changes in the differential pressure in a state where the master container and the work container are closed with the test pressure in the test differential pressure change measurement process. Cases 1 and 2 are shown in FIG. 2, and cases 3 to 6 are shown in FIG. In each case, the vertical direction corresponds to the pressure value or the differential pressure value, and the horizontal direction corresponds to the time. The change in the internal pressure of the master vessel M, the change in the internal pressure of the work vessel, and the change dP in the differential pressure between them. It is shown.

  Case 1 is an example in which neither of the internal pressures changes with the master container M and the work container W closed with the test pressure. In this case, there is no change in the differential pressure dP. Therefore, in case 1, it is determined that the work container has no leak. On the other hand, Case 2 is an example in which the internal pressures of the master container M and the work container W are increased in the same manner. Case 2 is an example in which the temperature of both the master container and the work container is higher than the outside air temperature, and the temperature in both containers rises during the test, thereby increasing both the internal pressure of the master container and the work container. There is no change in the resulting differential pressure dP. Therefore, even in case 2, the work container is determined to have no leak. In case 2, for example, even if the internal pressures of both the master container and the work container are lowered similarly, the differential pressure dP does not change and it is determined that the work container has no leak.

  In this way, by monitoring the change in the differential pressure with respect to the change in the internal pressure at the test pressure, even if the disturbance affects the master container and the work container in the same way, those effects can be offset. That is, if all conditions are the same between the master container and the work container, the pressure change due to the temperature change is not reflected in the differential pressure, and the presence or absence of the work container leak can be detected correctly. Furthermore, even if the test pressure is as high as 100 kPa, for example, since the measurement range of the differential pressure is small, the change in the differential pressure can be measured with high resolution.

  Case 3 in FIG. 3 is an example in which the internal pressure of the master container M is not changed, but the internal pressure of the work container W is decreased, thereby increasing the differential pressure dP. The decrease in the internal pressure of the work container M is when the test pressure is in a pressurized state and a leak occurs in the work container. Thus, when the differential pressure dP rises, it is determined that there is a leak and is determined to be a defective product (+ NG).

  On the other hand, in case 4, the internal pressure of the master container M is reduced, but the internal pressure of the work container W is not changed, and the differential pressure dP is thereby lowered. The reason why only the internal pressure of the master container is reduced is, for example, when the master container is not completely attached to the branch pipe 2 and a leak occurs on the master container side. Also in this case, since the test differential pressure change cannot be measured appropriately, it is determined as a defective product (−NG), and a retest is performed as necessary.

  However, in the case 5 of FIG. 3, as in the case 3, there is no change in the internal pressure of the master container M, but the internal pressure of the work container W is decreased, and thereby the differential pressure dP is increased. However, the decrease in the internal pressure of the work container is caused by, for example, the work container being in a high-temperature state immediately after the welding process, and in the test differential pressure change measurement process at the test pressure, being in a temperature decrease situation. Also in this case, the internal pressure of the work container decreases, so that the differential pressure dP increases. In this case, it is determined that there is a leak due to an increase in the differential pressure dP, and it is determined as a defective product (+ NG). However, there is no leak in the work container, and the determination as a defective product is an erroneous determination.

  In the case 6 of FIG. 3, unlike the case 4, the internal pressure of the master container M does not change, but the internal pressure of the work container W increases and the differential pressure dP decreases. However, the increase in the internal pressure of the work container is, for example, brought from a place where the work container is at a lower temperature than the master container attached to the pipe. The reason is that In this case, the differential pressure dP decreases and it is determined as a defective product (−NG). However, there is no leak in the work container, and the determination as a defective product is an erroneous determination.

  In order to distinguish between cases 3 and 5 in FIG. 3 and to distinguish between cases 4 and 6, in the leak test of the present embodiment, the temperature correction measurement mode is executed, and the master container and the work container are enlarged. A temperature correction value measuring step for measuring a change in the differential pressure dP as a temperature correction value in a state in which the master container and the work container are closed at a test pressure in a state where the pressure difference is blocked by the atmospheric pressure. The test differential pressure change measuring step to be measured is performed, the test differential pressure value is corrected based on the temperature correction value, and the presence or absence of leakage of the work container is determined based on the corrected test differential pressure value.

[Temperature compensation measurement mode]
The temperature correction measurement mode will be specifically described below.

  4 to 7 are diagrams showing examples of the temperature correction measurement mode in the differential pressure type leak test in the present embodiment. In each figure, the horizontal axis represents time, and the vertical axis represents the pressure P in the master container and the work container, and the differential pressure dP.

  In the temperature correction measurement mode, a test differential pressure change measurement step S2 for measuring a change in differential pressure as a test differential pressure value in a state where the master container and the work container are closed with the test pressure, and either before or after the test differential pressure change measurement process S2. On the other hand, temperature correction value measurement steps S1 and S2 are performed, in which a change in the differential pressure dP is measured as a temperature correction value in a state where the master container and the work container are closed at atmospheric pressure. The temperature correction value measurement step S1 performed before the test differential pressure change measurement step S2 is referred to as a pre-process, and the temperature correction value measurement step S3 performed after the test differential pressure change measurement step S2 is referred to as a post-process.

  After step S1 and before the start of step S2, the valves MV, WV, and PV are opened, the pressure pump 5 is driven, and the master container and the work container are pressurized to a test pressure of, for example, 100 kPa. The container side valve WV is closed and closed at the test pressure. Also, before the start of step S1 and after the end of step S2 and before the start of step S3, the atmospheric pressure valve AV, the master container side valve MV, and the work container side valve WV are opened, the pressurization side valve PV is closed, and the master container is closed. Then, the work container is brought to the atmospheric pressure state, and then the master container side valve MV and the work container side valve WV are closed to be closed at the atmospheric pressure.

  Furthermore, in the temperature correction measurement mode, the test differential pressure value, which is the change in the differential pressure at the test pressure, is corrected based on the temperature correction value, which is the differential pressure change at atmospheric pressure, and the corrected test differential pressure value is obtained. Based on this, the presence or absence of leakage of the work container is determined. If the corrected test differential pressure value (differential pressure change at the test pressure) does not exceed zero, that is, the reference value, it is considered that there is no pressure change due to leak in the work container, and it is judged as a good product without leak. On the contrary, if the corrected test differential pressure value exceeds the reference value, it is determined that the work container is a defective product because a leak has occurred in the work container or some trouble has occurred such as mounting of the master container.

  In the example of FIG. 4, the differential pressure dP is zero and does not change in the temperature correction value measurement steps S1 and S3. This means that there is no disturbance of temperature change between the master container and the work container. Similarly, in the test differential pressure change measurement step S2, the differential pressure dP is zero and does not change. Therefore, in this case, there is no temperature change in the master container and the work container during the leak test, and no leak occurs in the work container, and it is determined that the product is OK (OK).

  In the example of FIG. 5, the differential pressure dP is zero (DP1 = DP3 = 0) and does not change in the temperature correction value measurement steps S1 and S3. That is, there is no disturbance of temperature change between the master container and the work container. However, the differential pressure dP increases (DP2> 0) in the test differential pressure change measurement step S2. The increase in the differential pressure dP is the same as in the cases 3 and 5 of FIG. However, since the differential pressure dP is zero and has not changed in the temperature correction value measurement steps S1 and S3, it is found that the case 3 is not the case 5. The leak test apparatus corrects by removing the differential pressure changes DP1, DP3 = 0 in the temperature correction value measurement process S1 or S3 from the differential pressure change DP2 in the test differential pressure change measurement process S2, and corrects the correction. Based on the increase in the differential pressure change amount (DP2-DP1, DP2-DP3), it is determined that there is a leak and the product is defective (+ NG).

  In the example of FIG. 6, the differential pressure dP increases in the temperature correction value measurement steps S1 and S3 (DP1 = DP3> 0). For example, the differential pressure is increased because the temperature of the work container is increased. On the other hand, also in the test differential pressure change measurement step S2, the differential pressure dP increases by DP2. The amount of increase DP2 in the differential pressure is the same as that of cases 3 and 5 in FIG. However, the increase DP2 of the differential pressure dP is equal to the differential pressure changes DP1 and DP3 at atmospheric pressure. The leak test apparatus corrects the differential pressure change amount DP2 in the test differential pressure change measurement step S2 by removing the differential pressure change amount DP1 = DP3 (= DP2) in the temperature correction value measurement step S1 or S3. , Based on the fact that the corrected differential pressure variation (DP2-DP1, DP2-DP3) is zero and does not exceed the reference value, it is determined that the product is non-defective (OK) without leakage. That is, it becomes clear that it is case 5 instead of case 3.

  In the example of FIG. 7, the differential pressure dP increases in the temperature correction value measurement steps S1 and S3 (DP1 = DP3> 0). For example, the temperature of the work container increases. On the other hand, also in the test differential pressure change measurement step S2, the differential pressure dP increases by DP2. However, the increase amount DP2 of the differential pressure is larger than the differential pressure changes DP1 and DP3 at atmospheric pressure. The leak test apparatus corrects the differential pressure change amount DP2 in the test differential pressure change measurement step S2 by removing the differential pressure change amount DP1 = DP3 (<DP2) in the temperature correction value measurement step S1 or S3. Based on the fact that the corrected differential pressure variation (DP2-DP1> 0, DP2-DP3> 0) is still not zero and exceeds a predetermined reference value, it is determined that there is a leak (+ NG). To do.

  4 to 7, in the case where the differential pressure dP decreases due to the temperature rise of the work container during S1, S2, and S3 during the leak test, the influence of disturbance due to the temperature change is similarly removed. Thus, it is possible to determine whether or not there is a leak in the work container.

[Temperature compensation calculation]
As described above, in the temperature correction measurement mode, the test differential pressure value DP2 that is a change in the differential pressure at the test pressure is corrected based on the temperature correction value DP1 or DP3 that is the differential pressure change at the atmospheric pressure. Based on the test differential pressure value DP2-DP1 (or DP2-DP3), the presence / absence of leakage of the work container is determined. However, the density of the gas in the master container and the work container differs between the atmospheric pressure state and the test pressure state. Therefore, in the present embodiment, considering the difference in gas density, whether the differential pressure change amount in the atmospheric pressure state (test differential pressure value) or the differential pressure change amount in the test pressure state (temperature correction value) is used. Either of the above is corrected according to the difference in gas density, and the temperature correction value is subtracted from the test differential pressure value.

The equation of state of the ideal gas is as follows.
PV = ρRθ (1)
Where P: pressure (Pa), V: volume of container (m ³ ), ρ: density of air (Kg / m ³ ), R: gas constant (J / (Kg.K), θ: temperature (K) From this state equation (1), the pressure is as follows.
P = ρRθ / V
The differential pressure change amount (test differential pressure value) in the test pressure state is DP2 = ρ ₂ Rθ / V, and the differential pressure change amount (temperature correction value) in the atmospheric pressure state is DP1 = ρ ₁ Rθ / V. For example, the corrected differential pressure variation (corrected test differential pressure value) is as follows.
DP2−DP1 = ρ ₂ Rθ / V−ρ ₁ Rθ / V (2)
The ratio of the above equation (2), the gas density [rho ₂ of the test pressure (e.g. 100 kPa (G)), the gas density [rho ₁ at atmospheric pressure (0 kPa (G), 101.325 kPa (Abs)), [rho ₂ / [rho ₁ is a correction coefficient for the difference pressure variation of atmospheric pressure (temperature correction value) is 1.986 ≒ 1.99. Therefore, Formula (2) is as follows.
DP2-1.99 × DP1 = ρ ₂ Rθ / V−1.99 × ρ ₁ Rθ / V (2A)
[Temperature compensation value measurement mode and pressure measurement mode]
FIG. 8 is a diagram showing a temperature correction measurement mode in the present embodiment. Similar to FIGS. 4 to 7, the test differential pressure change measurement step S <b> 2 for measuring the change in the differential pressure (test differential pressure value) between the master container and the work container in the test pressure state, and the atmospheric pressure state before and after the difference. Temperature correction value measuring steps S1 and S3 for measuring a change in pressure (temperature correction value). Only one of the temperature correction value measurement steps S1 and S3 may be performed. However, when the temperature correction value measurement steps S1 and S3 are performed twice, the average value may be used as the temperature correction value.

  FIG. 9 is a diagram showing a pressure measurement mode in the present embodiment. In the pressure measurement mode, only the test differential pressure change measurement step S2 is performed without performing the temperature correction value measurement steps S1 and S3. Therefore, the pressure measurement mode can be implemented when the differential pressure change is zero in the temperature correction value measurement process, specifically when it does not exceed a predetermined reference value, and the test differential pressure value is corrected with the temperature correction value. First, depending on whether or not the test differential pressure value has changed, that is, whether or not a predetermined reference value has been exceeded, it is determined that the test has failed (defective product, + NG, -NG) or test pass (good product, OK). . In the case of a test failure (+ NG, -NG) in the pressure measurement mode, there is a possibility of a pressure change due to a temperature change. Therefore, whether or not there is a leak with the test differential pressure value corrected by performing the temperature correction measurement mode again. Determine.

  FIG. 10 is a state transition diagram of the temperature correction measurement mode S11 and the pressure measurement mode S14 in the leak test according to the present embodiment. FIG. 11 is a diagram showing an example of the leak test. The leak test of FIG. 10 will be described with reference to FIG.

  In the leak test process for a plurality of work containers, at a test start time S10, a work container leak test is performed in the temperature correction measurement mode S11. That is, as shown in FIG. 8, the temperature correction value measurement steps S1 and S3 in the atmospheric pressure state and the test differential pressure change measurement step S2 in the test pressure state are performed, and the differential pressure change at the test pressure is temperature corrected. Correct by value. When the differential pressure change occurs in the temperature correction value measurement steps S1 and S3 in the atmospheric pressure state in the temperature correction measurement mode S11 and is not zero, that is, when the differential pressure change exceeds a predetermined reference value (S12), Since the differential pressure change due to the temperature change has occurred and temperature correction is required, the leak test for the next workpiece container is repeated in the temperature correction measurement mode S11 of FIG. The change in the differential pressure in the atmospheric pressure state in S12 is the case as shown in FIGS.

  On the other hand, if the differential pressure change is zero in the temperature correction value measurement steps S1 and S3 in the atmospheric pressure state in the temperature correction measurement mode, that is, if the predetermined reference value is not exceeded (S13), the differential pressure change due to the temperature change occurs. 9 is performed in the pressure measurement mode S14 of FIG. 9 from the leak test for the next work container. The fact that there is no differential pressure change in the atmospheric pressure state in S13 is the case as shown in FIGS. If the leak test result in the pressure measurement mode S14 is a non-defective product (OK) determination, the leak test in the pressure measurement mode S14 is repeated. In the pressure measurement mode S14, the temperature correction value measurement steps S1 and S3 for measuring the differential pressure change in the atmospheric pressure state can be omitted, so that the leak test time can be shortened.

  In the pressure measurement mode S14, the temperature correction value measurement steps S1 and S3 in the atmospheric pressure state are omitted, and the presence or absence of the differential pressure change obtained in the test differential pressure change measurement step S2 in which the differential pressure change is measured in the test pressure state. The following four states can be determined. That is, first, if there is no change in the differential pressure in the test pressure state, the work container is determined to be a non-defective product (OK) on the assumption that there is no influence of the temperature change. Second to fourth, when a differential pressure change occurs in the test pressure state, as described in FIGS. 5, 6, and 7, there is no effect of temperature change and a leak occurs in the work container (in the case of FIG. 5). ), When there is no leak in the work container but there is an effect of temperature change (in the case of FIG. 6), and when there is an effect of temperature change and there is a leak in the work container (see FIG. 6). 7).

  Therefore, in the pressure measurement mode S14, while the non-defective product (OK) determination is made (S15), the pressure measurement mode S14 is repeatedly performed because the first state is described above. However, if a defective product (+ NG, -NG) determination is made (S16), it is necessary to confirm that it is one of the above-mentioned second to fourth. In S11, the leak test is performed again. According to the temperature correction measurement mode S11, the three states of FIGS. 5, 6, and 7 can be distinguished, and a good product and a defective product can be appropriately distinguished.

  As described above, if there is a differential pressure change in the atmospheric pressure state in the temperature correction measurement mode S11 (S12), the temperature correction measurement mode S11 is repeated for the next workpiece container, but the differential pressure change in the atmospheric pressure state is repeated. If not (S13), the process proceeds to the pressure measurement mode S14.

  FIG. 11 shows an example in which the state transition of FIG. 10 is applied. When (1) temperature correction measurement mode in FIG. 11 is zero and the differential pressure change is zero in the atmospheric pressure state, (2) transition to pressure measurement mode. In the pressure measurement mode of FIG. 11 (2), when a change in the differential pressure occurs in the test pressure state and a defective product (+ NG) is determined, the temperature correction measurement mode of FIGS. 11 (3A) and (3B). Migrate to (3A) is the same as FIG. 6, and is an example in which the change in the differential pressure of the test pressure subjected to temperature correction is zero and the product is determined to be non-defective (OK). Further, (3B) is the same as FIGS. 5 and 7, and is an example in which the change in the differential pressure at the temperature-corrected test pressure is determined to be defective (+ NG) instead of zero.

  As described above, in the leak test in the present embodiment, when the differential pressure change in the atmospheric pressure state is zero, the process proceeds to the pressure measurement mode S14 in which the temperature correction value measurement process is omitted, and the differential pressure change in the test pressure state. Is zero and the non-defective product (OK) determination is made, the pressure measurement mode S14 is repeated. As a result, the leak test time is shortened while eliminating the erroneous determination of the leak test.

  FIG. 12 is a diagram illustrating an example in which an erroneous determination occurs in the leak test. FIG. 12 (1) shows the differential pressure changes DP1 and DP3 in the temperature correction value measurement steps S1 and S3 in the atmospheric pressure state in the temperature correction measurement mode. However, when the differential pressure changes DP1 and DP3 in the temperature correction value measurement process repeat the same value, it is assumed that the temperature change is stably repeated, and the pressure correction measurement process is omitted. It can be considered to shift to the mode. In the pressure measurement mode of FIG. 12 (2), the temperature correction value measurement steps S1 and S3 are omitted, and temperature correction is performed using the temperature correction values DP1 and DP3 obtained in the temperature correction measurement mode of FIG. 12 (1). Is called. In the example of FIG. 12 (2), a differential pressure change DP2 occurs in the same test pressure state as in (1), and DP2-DP1 (or DP3) is obtained by subtracting the temperature correction values DP1 and PD3 obtained in (1). = 0 is obtained, it is determined that there is no change in the differential pressure due to leakage in the test pressure state, and a non-defective product (OK) is determined.

  However, the pressure measurement mode (2) in FIG. 12 may actually have two states (2A) and (2B) in FIG. That is, in (2A), DP2 = DP1 and DP3 as in (1), and the non-defective product determination is correct. On the other hand, in (2B), unlike (1), the temperature correction values DP1 and DP2 obtained in the atmospheric pressure state are zero or smaller than DP1 and DP3 in (1). In this case, the value DP2-DP1 (or DP3) after temperature correction is> 0, and a defective product (+ NG) should be determined. Therefore, it can be understood that the non-defective product (OK) determination in (2) of FIG. 12 is an erroneous determination.

  As described above, if the pressure measurement mode without the process is shifted to the pressure measurement mode simply because the differential pressure changes DP1 and DP3 detected in the temperature correction value measurement process are stably repeated, there is a possibility of erroneous determination. Is not preferable.

  On the other hand, the leak test method of FIGS. 10 and 11 in the present embodiment does not cause an erroneous determination as shown in FIG. That is, according to the present embodiment, it is possible to shorten the leak test time while avoiding erroneous determination.

  The leak test apparatus shown in FIG. 1 performs a leak test based on the state transition shown in FIG. The state transition of FIG. 10 is as described above. In addition to the above description, when the pressure measurement mode step S14 is repeated n times that is a predetermined number of times, the state is forcibly shifted to the temperature correction measurement mode S11. Then, the temperature correction value measurement process is performed again to confirm that the differential pressure change at atmospheric pressure is zero. Alternatively, when the leak test is interrupted for a predetermined time such as a lunch break while the pressure measurement mode process S14 is being repeated, it is desirable to shift to the temperature correction measurement mode S11. This is because the probability that a differential pressure change due to a temperature change occurs with the passage of time increases.

[Operation of leak test equipment]
FIG. 13 is an operation flowchart of the leak test apparatus in the present embodiment. In the test operation of the leak test equipment shown here, in the temperature compensation measurement mode, as a rule, the test differential pressure obtained in the test differential pressure change measurement process using the temperature compensation value obtained in the temperature compensation value measurement process S1 of the previous process. The leak is judged by correcting the value. If the leak determination is a non-defective product (OK), the temperature correction value measurement step S3 in the subsequent process is not performed. On the other hand, if the leak judgment is poor (+ NG, -NG), the temperature correction value measurement step S3 in the subsequent process is performed, and the test differential pressure value is corrected with the average value of the temperature correction values in the previous process and the subsequent process. Perform leak judgment.

  Furthermore, in the pressure measurement mode, a leak judgment is performed based on the test differential pressure value obtained in the test differential pressure change measurement step S2, and if the leak judgment is poor (+ NG, -NG), a temperature correction value measurement step is performed, Accordingly, the test differential pressure value is corrected using the obtained temperature correction value, and the leak determination is performed again. That is, the temperature correction measurement mode process is performed by the test differential pressure change measurement process S2 in the pressure measurement mode and the subsequent temperature correction value measurement process.

  The operation of the leak test apparatus will be described with reference to FIG. When the start button is turned on, the leak test is started and the variables N, Y, and Z are reset to the initial value 0 (S20). Variable N is the number of consecutive pressure measurement modes, variable Y is the number of retries used in a later-described modification, and variable Z is a flag indicating temperature correction measurement mode (Z = 1) and pressure measurement mode (Z = 0) . In step S21, the variables Z and N are reset to the initial value 0.

  Then, the temperature correction value measurement step S1 of the previous step is started (S22). That is, once the valves MV, WV and the pressure reducing valve AV shown in FIG. 1 are opened, the supply valve PV is closed, the master container and the work container are brought to atmospheric pressure (S23), and then the opened valves MV, Close WV and AV (S24). Both containers are now closed at atmospheric pressure. Then, it is determined whether there is no change in the differential pressure measured by the differential pressure sensor (S25). If there is a change in the differential pressure, the flag Z is set to Z = 1 to set the temperature correction measurement mode (S26). If there is no change in the differential pressure, the flag Z is the initial value Z = 0 and the pressure measurement mode is set.

  If there is no change in the differential pressure in the atmospheric pressure state, the pressure measurement mode (Z = 0) is entered, and the number of times N is set to N + 1 (S27). Then, differential pressure measurement in the pressurized state (test differential pressure measurement step S2) is started (S28). That is, the valves MV, WV, and PV are opened and pressurized from the pressure pump 5 (S29). At this time, the pressure value of a single pressure sensor (not shown) attached to the workpiece side pipe 3 in FIG. 1 is fed back so that the pressure in the workpiece container becomes a desired pressure. When the desired pressure is reached, the valves MV and WV are closed to close both containers (S30). Then, the change in the differential pressure in this pressurized state is measured. If Z = 0 (NO in S31), the presence or absence of a leak is determined based on whether or not there is a change in the differential pressure (S34). When Z = 1, the temperature correction measurement mode is set, and therefore the presence or absence of a leak is determined based on the differential pressure change corrected using the temperature correction value (S32).

  Now assume that the pressure measurement mode (Z = 0). Therefore, a leak judgment is made based on the differential pressure change in the pressurized state (S34). If there is no leak, the supply valve PV is closed (S35), the valves MV, WV, AV are opened, and the master container and work container Are released to atmospheric pressure (S36). Then, the leak test apparatus turns on the pass lamp (S37) and outputs a workpiece replacement instruction (S38). When the operator replaces the work container and turns on the start switch (S39), the leak test for the next work container is started. X = 0, Y = 0 in the step S40 is for a modified example to be described later. In step S41, it is confirmed whether the number N of pressure measurement modes has reached a predetermined value n (for example, 10 times). If not, Z = 0 is confirmed in step S42, and the process returns to step S27.

  For the next work container, the pressure measurement mode from steps S27 to S31 and S34 to S38 is performed, and the number of times N reaches n = 10 as long as the leak judgment is no leak (good product OK). Until the test is interrupted for a predetermined time in the middle (until the replacement timer for measuring the time for replacing the work container in S55 and S56 is over), the pressure measurement mode is repeated. When the number N reaches 10 in step S56 or when the test is interrupted, the process returns to step S21, and the temperature correction value measurement step S22 is executed again. After the time-out due to interruption, the leak test is resumed when the start switch is turned on (S57).

  Another condition for transitioning from the pressure measurement mode to the temperature correction measurement mode is when there is a leak (+ NG, −NG) (S43) in the leak determination in step S34. In this case, the temperature correction value measurement step (S44) is started, the valves MV, WV, AV are opened, the valve PV is closed, the master container and the work container are released to atmospheric pressure (S45), and then the valves MV, WV, The AV is closed and closed (S46). Then, the change in the differential pressure in the atmospheric pressure state is detected as a temperature correction value. Since Z = 0, the process branches to NO in step S47, and the change in the differential pressure in the test pressure state is detected using the current temperature correction value. Correction is made to determine whether or not there is a leak (S52). If it is determined that there is a leak (defective product), the leak tester turns on the defective lamp (S49), closes the supply valve PV, opens the other valves MV, WV, AV (S50), and the master container. And the work container is released to atmospheric pressure, and a work replacement instruction is output (S38). In step S51, Z = 1 is set to change to the temperature correction measurement mode.

  Next, the test operation in the temperature correction measurement mode (Z = 0) will be described. Perform the temperature correction value measurement process S22-S25 of the previous process, perform the test differential pressure change measurement process S28-S30, and perform leak determination based on the differential pressure change in the pressurized state corrected using the temperature correction value ( S32). If there is no leak (YES in S32), the pass lamp is turned on (S37), and the work replacement is instructed (S38).

  If there is a leak (NO in S32), perform the temperature correction value measurement process S44-S46 in the subsequent process, and change the pressure difference in the pressurized state corrected by the average value of the temperature correction value in the previous process and the subsequent process. Based on this, a leak determination is made (S48). If there is a leak (defective product), the defective lamp is turned on (S49), and the master container and the work container are released to atmospheric pressure (S50). If there is no leak (non-defective), the master container and the work container are released to atmospheric pressure (S53), and the acceptance lamp is turned on (S54). Then, the workpiece replacement is instructed (S38), and the start switch on after the workpiece container replacement is waited (S39).

[First Modification of Operation of Leak Test Apparatus]
FIG. 14 is a flowchart of Modification Example 1 of the operation of the leak test apparatus in the present embodiment. In the operation of the leak test apparatus, steps S60 to S67 are added to FIG. In this process S60-S67, if there is a leak (defect + NG, -NG) during the pressure measurement mode (NO in S34), it does not immediately switch to the temperature correction measurement mode, Repeat the pressure measurement mode with the number of times y as the upper limit of the number of repetitions, and check if there is no leak. That is, after the release to atmospheric pressure (S63, S64), the test differential pressure change measurement process consisting of pressurization to the test pressure (S28-S30) and leak judgment based on the differential pressure change in the pressurized state (S32) Repeat until the number of repetitions Y = y is the upper limit until there is no leak (good product OK). However, if the number X reaches the predetermined number x (x <y) during the repetition up to the predetermined number y (YES in S65), the cooling fan is turned on (S66), and the master container and work container are connected with the cooling fan. While cooling, repeat the test differential pressure change measurement process (S28-S30, S32) with the number of repetitions Y = y as the upper limit until there is no leak (good product OK). When the work test is completed, the cooling fan is turned off (S67).

  That is, if it is determined that there is a leak in the pressurization measurement mode in step S34, the number of repetitions Y is incremented (S43), and the upper limit value Y = y is reached (NO in S60), and atmospheric pressure is detected in steps S61-S64. Then, repeat the test differential pressure change measurement process (S28-S30, S32). When the number of repetitions X reaches the predetermined number x, the cooling fan is turned on (S66), and the process is repeated until the upper limit value Y = y is reached again.

  Even if it is determined that there is a leak in the pressurization measurement mode, it may be determined that there is no leak while the test differential pressure change measurement process is repeated. The reason is, for example, the case where the work container is not completely installed due to dust or the like. On the other hand, when the test differential pressure change measurement process is repeated, the pressure injection into the master container and the work container is repeated and heated, and the master container and the work container are heated even though the work container is good. There is a case where the behavior of the pressure fluctuation is different and the differential pressure change is detected and it is erroneously determined that there is a leak. Therefore, when repeating the test differential pressure change measurement process in the pressure measurement mode, it is effective to repeat the cooling while cooling the master container and the work container after a predetermined number of times of pressure injection. In the first modification, the cooling is performed by air cooling with a cooling fan.

[Modification 2 of operation of leak test apparatus]
FIG. 15 is a flowchart of a second modification of the operation of the leak test apparatus in the present embodiment. In this leak test apparatus, instead of the air cooling process by the cooling fan in FIG. 14, a cooling method is performed by purging the master container and the work container from the pressure pump while purging the pressurized air to the atmospheric pressure. .

  That is, in FIG. 1, a purge valve for connecting to the atmospheric pressure is provided in the master side branch pipe 2 and the work side branch pipe 3. Alternatively, if the shapes of the master container and the work container allow, a purge valve may be attached on the opposite side of the master container and the work container from the branch pipes 2 and 3.

  Then, after it is determined that there is a leak in the pressure measurement mode, when the test differential pressure change measurement process in the pressure measurement mode is repeated with the number of times y as the upper limit, when the number of repetitions X reaches the predetermined number y (YES in S65). ), Steps S70 to S74 are performed. In other words, the pressure reducing valve AV is closed, the purge valve is opened, the supply valve PV is opened (S70), pressurized air is injected from the pressure pump, and cold air is injected into the master container and the work container. Purge cooling is started to circulate low temperature air that escapes to atmospheric pressure (S71). After purging with this low temperature air for a predetermined time (S72), the purge valve is closed (S74). At this time, the number of repetitions X is reset to X = 0. Thus, purge cooling with this low-temperature air is performed every time the number X reaches a predetermined number x (x <y) until the number of repetitions Y reaches the upper limit value y.

  By purging with low-temperature air as described above, the temperatures of the master container and the work container can be lowered more effectively than air cooling with a cooling fan. Other operations are the same as those in FIGS.

  As described above, according to this embodiment, when the change in the differential pressure in the temperature correction value measurement process is zero, that is, smaller than the reference value during the temperature correction measurement mode, the process proceeds to the pressure measurement mode and the temperature correction value measurement process is performed. Since it is omitted, the leak test time can be shortened.

  In addition, after the transition to the pressure measurement mode, when the leak determination becomes a leak, the leak determination is performed by returning to the temperature correction measurement mode and correcting with the temperature correction value, thereby preventing erroneous determination.

  In addition, even if it is judged that there is a leak in the pressure measurement mode, if the pressure measurement mode can be repeated up to a predetermined number of times to obtain a judgment that there is no leak, the pressure measurement can be made without switching to the temperature correction measurement mode. The mode can be continued and the man-hours for the leak test can be reduced.

MA: Master container WA: Work container 4: Differential pressure sensor 5: Pressure pump 10: Leak test device S11: Temperature correction measurement mode S14: Pressure measurement mode

Claims (11)

A temperature correction value measuring step for measuring a change in the differential pressure between the internal pressure of the master container and the work container as a temperature correction value in a state where the master container and the work container are closed at atmospheric pressure, and the master container and the work container. A test differential pressure change measuring step of measuring a change in the differential pressure as a test differential pressure value in a state of being blocked with a test pressure other than the atmospheric pressure, and correcting the test differential pressure value based on the temperature correction value. , Performing a temperature correction measurement mode step of determining whether or not the work container has leaked based on the corrected test differential pressure value,
When the change in differential pressure measured in the temperature correction value measurement step in the temperature correction measurement mode step does not exceed the first reference value, the test differential pressure change measurement step is performed and measured in the test differential pressure change measurement step. The process proceeds to a pressure measurement mode process for determining whether or not there is a leak in the work container based on the test differential pressure value.
A leak test method for returning to the temperature correction measurement mode step when it is determined that there is a leak in the pressure measurement mode step. In claim 1,
In the pressure measurement mode step, a leak test method for determining that the leak is present when a change in the differential pressure of the test differential pressure value exceeds a second reference value. In claim 1 or 2,
A leak test method in which the pressure measurement mode process is repeated when a change in the differential pressure of the test differential pressure value in the pressure measurement mode process does not exceed a second reference value. In claim 1 or 2,
A leak test method for returning to the temperature correction measurement mode step when the pressure measurement mode step is repeated a first predetermined number of times or when a predetermined time has elapsed after the pressure measurement mode step. In claim 1 or 2,
When it is determined in the pressure measurement mode step that the work container is leaked, the pressure measurement mode step is repeated with the second predetermined number of times as an upper limit, and then the temperature correction measurement mode step is returned to. A leak test method for performing the pressure measurement mode process on the next workpiece container when it is determined that there is no leak during the repetition of the pressure measurement mode process with the predetermined number of times as the upper limit. In claim 5,
A leak test method in which the master container and the work container are either cooled by a cooling fan or cooled by inflow and outflow of low-temperature air during the repetition of the pressure measurement mode process having the upper limit of the second predetermined number of times. An atmospheric pressure adjusting means for closing the master container and the work container in an atmospheric pressure state, a test pressure adjusting means for closing the master container and the work container with a test pressure other than the atmospheric pressure, and an internal pressure of the master container and the work container In a leak test device connected to a differential pressure sensor that measures the differential pressure of
A temperature correction value measuring step of acquiring a change in differential pressure detected by the differential pressure sensor as a temperature correction value in a state where the master container and the work container are closed at atmospheric pressure by the atmospheric pressure adjusting means; and the test pressure adjustment And a test differential pressure change measuring step of acquiring a change in differential pressure detected by the differential pressure sensor as a test differential pressure value in a state where the master container and the work container are closed with the test pressure by means, Performing a temperature correction measurement mode step of correcting a pressure value based on the temperature correction value, and determining the presence or absence of leakage of the work container based on the corrected test differential pressure value;
When the change in differential pressure measured in the temperature correction value measurement step in the temperature correction measurement mode step does not exceed the first reference value, the test differential pressure change measurement step is performed and measured in the test differential pressure change measurement step. The process proceeds to a pressure measurement mode process for determining whether or not there is a leak in the work container based on the test differential pressure value.
A leak test apparatus that returns to the temperature correction measurement mode step when it is determined that there is a leak in the pressure measurement mode step. In claim 7,
A leak test apparatus that repeats the pressure measurement mode process when a change in the differential pressure of the test differential pressure value in the pressure measurement mode process does not exceed a second reference value. In claim 7,
A leak test apparatus that returns to the temperature correction measurement mode step when the pressure measurement mode step is repeated a predetermined number of times or when a predetermined time has elapsed after the pressure measurement mode step. In claim 7,
When it is determined in the pressure measurement mode step that the work container is leaked, the pressure measurement mode step is repeated with the second predetermined number of times as an upper limit, and then the temperature correction measurement mode step is returned to. A leak test apparatus that performs the pressure measurement mode process for the next workpiece container when it is determined that there is no leak during the repetition of the pressure measurement mode process with the predetermined number of times as the upper limit. In claim 10,
A leak test apparatus that performs either cooling of the master container and the work container by a cooling fan or cooling by inflow and outflow of low-temperature air during the repetition of the pressure measurement mode process having the upper limit of the second predetermined number of times.

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