JPS59166835A - Pressure variation detecting type leakage inspecting device - Google Patents

Abstract

PURPOSE:To always maintain a constant inspection accuracy by using a mean value obtained by calculating a mean value of an inspected data of a prescribed number of objects to be inspected, as a correcting value to the inspected data of the object to be inspected, correcting the inspected data, and also correcting only the first inspecting cycle by the correcting value set in advance. CONSTITUTION:A correcting value delta1 of the first time is given from a first time correcting quantity setting device 53, and a corrected data DELTAP1 is obtained by correcting an inspected data D1 by said correcting value delta1. This corrected data P1 is given to a quality deciding and comparing part 49. In an inspecting cycle of the second time, a changeover switch 52 is switched to a mean value operating part 44 side. In a storage device 42c, the inspected data value D1 of the first time becomes a correcting value delta2 of an inspected data D2 of the second time, and in an inspected data of the third time, the inspected data D1 of the first time and the inspected data value D2 of the second time are stored, therefore, the mean value operating part 44 calculates a mean value delta3 of the inspected data D1 and D2, this mean value delta3 is supplied to a correcting quantity converting part 45, and an inspected data D3 of the third time is corrected. A corrected data DELTA P2 is given to the quality deciding and comparing part.

Description

[Detailed Description of the Invention] <Technical Field of the Invention> This invention is designed to prevent fluid leakage during use.
Or, regarding leak testing equipment that sequentially inspects products or parts that must meet certain standards during the production process to determine pass/fail, to automatically correct errors in measurement data caused by the measurement atmosphere, etc. The present invention aims to provide a leak inspection device with an automatic correction function that can perform the following steps.

<Description of Prior Art> FIG. 1 is a block diagram showing the configuration of a leakage testing device that has already been put into practical use. The flow pipe 1o connected to the output side of the air pressure source 11 is connected to the solenoid valve 1 via the pressure regulating valve 12 and the solenoid valve 14.
It is divided into two parts at the exit side of No. 4, and connected to branch paths 15-1 and 15-2, respectively.

A pressure gauge 13 is connected between the outlet of the pressure regulating valve 12 and the inlet of the electromagnetic valve 14 to set the test pressure.

The branch path 15-1 is connected to one end of a conduit 18 via a solenoid valve 16, and the other end of this conduit 18 is provided with a mechanism for connecting an object 20 to be inspected for leakage. This conduit 1
A mechanism at the other end of the test piece 8 connects the test objects 20 one after another to enable leakage testing. On the other hand, branch road 15
-2 is connected to one end of the conduit 19 via the solenoid valve 17;
A reference tank 21 is connected to the other end of the conduit 19.

Conduits 18 and 19 on the outlet side of solenoid valves 16 and 17
A differential pressure detector 22 is installed between them.

The output signal of the differential pressure detector 22 is given to a comparator 32 via an amplifier 31, and in the comparator 32, a reference signal setter 3
The configuration allows comparison with the output reference value of No. 3.

<Explanation of operation in Fig. 1> The object to be inspected 20 is attached to the end of the conduit 18, the leak-free reference tank 21 is attached to the conduit 19, the solenoid valve 14 is closed, and the pressure regulating valve 12 is opened. The air pressure applied from the air pressure source 11 is adjusted by the pressure gauge 13 to a predetermined value. Next, the solenoid valves 16 and 17 are opened, and the solenoid valve 14 is opened to supply air at a set constant pressure to the test object 20 and the reference through the branch path 15-1.15-2 and the conduit 18.19. It is supplied to the tank 21. This state is defined as a pressurization or exhaust period as shown in FIG. 2A, and the time period is represented by T1.

After a certain period of time T1 has elapsed since the electromagnetic valves 16 and 17 were fully opened and the pressure in the test object 20 and the reference tank 21 had stabilized, the electromagnetic valves 16 and 17 were closed. Furthermore, after a predetermined stabilization time T2 (this time T2 is referred to as an equilibrium period), the automatic zero correction formula connected to the differential pressure detector 22 is connected to the amplifier 3.
A zero correction signal 34 is applied to the amplifier 31, and the output of the amplifier 31 is set to zero in advance, and the output signal of the amplifier 31 is read after a certain period of time T1 from the time of zero setting.

The time T3 from the time of zero setting until nine readings are performed is referred to as a measurement time. When the zero point of the amplifier 31 is set, the amplifier 31
The sensitivity of is switched to a high sensitivity state.

Therefore, in the state where the output of the amplifier 31 is read, the differential pressure detector 2
The second detection signal is greatly enlarged and read.

Here, the solenoid valve 16.17 is controlled to open and the pressure is applied for a period T+, the solenoid valve 16.17 is closed and the pressure is stabilized T2, and the time from setting the amplifier 31 to zero until reading is taken. The entire inspection time T8 is referred to as one inspection cycle.

This period'f1. 'f2. 'rs switching is performed by the sequence controller 54.

When the inspection object 20 is completely airtight and there is no leakage, the output signal from the amplifier 31 ideally becomes zero during a certain measurement time. If there is a leak at 2° of the object to be inspected,
If the internal pressure is positive, the positive pressure will gradually decrease,
In the case of negative pressure, an output signal in which the pressure gradually increases is obtained, and the output signal within a certain detection time has a value proportional to the amount of negative or positive leakage.

The reference signal given from the reference signal setter 33 and the amplifier 3
The output signals of 1 are compared by a comparator 32, and if the output signal does not exceed the reference signal, a quality determination output 35 is obtained indicating whether the product is good or defective.

<Problems with pressure change detection type or differential pressure detection type leak detection device> In this conventional pressure change detection type leak detection device, the reference tank 21 has exactly the same shape as the object 2o to be inspected and is resistant to leakage. However, the output signal ideally remains at zero because it is affected by factors such as the temperature difference between the test object 20 and the reference tank 21, the internal capacity, slight deformation of the shape, and the difference in adhering moisture. I can't get it. In other words, due to these factors, even if there is no leakage at all in the inspected object 2°, the output signal within a certain testing time will not be in the ideal zero state, but will be positive or negative as shown in Figure 2B. It usually shows a value ΔP comparable to the amount of leakage.

If the errors caused by these factors are always constant for each measurement cycle, they can be corrected in advance during use, but in reality, the atmospheric conditions over a long period of time, i.e., ambient temperature, humidity, supply air temperature, etc. , the temperature of the test object 20 and the reference tank 21, and factors such as attached moisture gradually change.

In addition, deformation of the rubber that seals the opening of the test object 20 may occur, and based on these factors, when testing a large number of test foods 20 flowing through the production process line with a blowgun, it is necessary to between days or each day.

Errors based on these factors change from time to time or seasonally or over the years.

<Disadvantages of conventional leak testing devices> In conventional pressure change detection type or differential pressure detection type leak testing devices, there are errors based on factors that change over time, and the output standard of the reference signal setting device 33 is used for pass/fail judgment. I had to change the values frequently. However, this is not desirable for a leak testing device intended for labor saving and automation, and it has been difficult to perform highly accurate leak testing with this operation.

<Purpose of the Invention> The present invention solves the various problems in the conventional leakage testing device described above, automatically corrects for changes in factors within a predetermined period, except for variations in the inspected object itself, and constantly The present invention provides a leakage inspection device having an automatic error correction function capable of maintaining a constant inspection accuracy.

<Summary of the Invention> According to the present invention, a constant fluid pressure is applied to an object to be inspected, and changes in the pressure of this object to be inspected are detected over time, or a leak-free reference tank to which a constant fluid pressure is applied is used. In a leak test device that determines the quality of the inspected object by capturing the change in the differential pressure over time and comparing it with a preset standard judgment value, the inspection data of the inspected object that has been determined to be good is a storage means for storing a predetermined number of measurements, a calculation means for calculating an average value of the inspection data stored in the storage means, and the average value obtained by the calculation means as a correction value for the inspection data of the object to be inspected; The apparatus is provided with a data correction means for correcting the measurement data based on this correction value, and an initial correction means for correcting the measurement data using a preset correction value only in the first measurement cycle at the start of operation.

<Embodiments of the Invention> The automatic error correction and leakage inspection device of the present invention will be described in detail below based on embodiments using the drawings.

FIG. 3 is a diagram showing the configuration of a main part of an embodiment of the present invention, in which the output terminal of the differential pressure detector 22 is connected to the input terminal of an amplifier 31, and the output terminal of the amplifier 31 is connected to an A-D converter 41. The input end of is connected. These differential pressure detector 22, amplifier 31 and A-
The D converter 41 constitutes a measuring means. This A-D
The output terminal of the converter 41 is connected to the output display 548 and the input terminal of the comparison section 49 via the data correction section 47 .

On the other hand, the output of the A-D converter 41 is supplied to the storage means 42. The storage means 42 includes an error upper limit value setter 42a and a
-When the output value of the Dg converter 41 reaches the error upper limit value set in this setting device 4.2a and is smaller than PM, the output data is passed and the output data of the A-D converter 41 is set to the error upper limit value △PM. It is constituted by a gate means 42b that prevents the data from passing when the error is large, and an error storage 42C that stores only the data that has passed through the gate means 42b. Therefore, the error storage unit 42C stores only error data that is smaller than the error upper limit value △PM, l:, set in the setter 4'2a. A set number of data are read out and given to the average value calculation section 44.

The average value calculating section 44 calculates the average value of the data given from the error data storage device 42C, and supplies the average value to the correction amount converting section 45 through the changeover switch 52.

The correction amount converting section 45 calculates the correction amount δ=''t×ΔP using, for example, the measurement time T3 and the average error value ΔP given from the average value calculation section 44. Here, 3 T indicates the elapsed time, and it is assumed that it changes from T-0 to T=T8. Through this calculation, the correction amount δ is obtained from the correction amount converter 45 as a digital code that gradually increases from δ-0 to δ=ΔP as time T passes. This correction value δ is given to the data correction section 47 to correct the measurement data ΔPi output from the DA converter 41.

In this invention, an initial correction amount setter 53 is provided in addition to the average value calculation section 44 on the input side of the correction amount conversion section 45, and the initial correction amount setting device 53 is set only at the first measurement at the start of operation. The measurement data is corrected using the correction value, and the average value of the measurement data is used as the correction value from the second time onwards. The average value is the average value of the number of samples set in the sample number setting device 43. In other words, when the number of samples is set to N, the average value of the current measurement data and the number of N samples before is calculated. In the next measurement cycle, the oldest N pieces of previous measurement data is removed, and the measurement data from that cycle is added to calculate the average value. This is generally called a moving average. Until the number of error data stored in the error storage device 42C reaches N, the average value of the stored data is calculated. Note that 54 indicates a controller that sequentially controls the operations of each part.

<Operation of the invention> At the start of operation, the selector switch 52 is set to the initial correction amount setter 5.
Switch to side 3. The initial correction amount setter 53 is set with the final correction value of the previous day or a correction value obtained empirically in advance for that season. The correction operation will be explained using FIG. 4. DI shown in FIG. 4A, D2. Ds,...I)
n is the measurement data of each measurement cycle. For example, D exceeding the error upper limit △PM among the measurement data D1~on
1 is prevented from passing through by the gate means 42b and is not stored in the memory 42c. δ1 to δn shown in FIG. 4B indicate correction values for correcting each of the measurement data D1 to Dn.

Here, the initial correction value δl is given from the initial correction amount setter 53, and by correcting the measurement data D1 using this correction value δl, the correction amount data ΔP1 shown in FIG. 4C is obtained. This correction amount data p+ is given to the pass/fail judgment comparison section 49, where it is compared with the limit value ΔPs given from the pass/fail judgment limit setter 50. If the corrected data ΔP1 is within the limit value range, a good signal 51 is output. The corrected data ΔP1 is also given to a display 48 in addition to the pass/fail judgment comparison section 49, and displays the data value of the correction amount (value corresponding to the differential pressure).

In the second measurement cycle, the changeover switch 52 is switched to the average value calculation section 44 side. 1 for the storage device 42c
The first measurement data value D1 is the correction value δ2 of the second measurement data D2, and the first measurement data D1 and the second measurement data value D2 are stored in the third measurement data. Therefore, the average value calculation unit 44 calculates the average value δ3 of the measurement data ΔD] and D2, and converts this average value δ8 into the correction amount conversion unit 4.
5 to correct the third measurement data D3. If the correction amount data ΔP2 is smaller than the pass/fail limit value ΔPs, the pass/fail determination comparison section 49 outputs a pass signal 51.

Similarly, the measurement data D4 is the measurement data D1. D2, D
It is corrected using the average value δ4 of s. As a result of this correction, is the corrected data △P4 obtained? If △P4 exceeds the pass/fail judgment limit value △Ps, for example, the pass/fail judgment comparison unit 49
A defective signal 511 is output from. In this case, the measurement data D4 is not taken into the memory 42c.

In this way, the number of correction data increases sequentially until the number of samples stored in the storage device 42c reaches the number N set in the sampling number setting device 43.

When the number of samples reaches N, after that, the average value is calculated by excluding the previous data by the set number of samples N instead of adding the measurement data of that time to calculate the average value.

When the inspection data D1 in the next inspection cycle exceeds the correction amount limit value △PM set in the correction amount limit setter 42a, it is determined that there is an abnormal leakage other than the object to be inspected, and this is stored in the memory. 42c.

<Effects of the Invention> As described above, according to the present invention, the measurement data is corrected by the correction value set by the initial correction amount setting means 53 only in the first measurement cycle, and from the second time onwards, in each measurement cycle. Since the average value of the obtained error values is used as the correction value, highly accurate tests can be performed from the beginning of operation.

Furthermore, even if the error changes slightly during operation, the error can be averaged and obtained as a correction value, so that leak inspection can be performed with high accuracy from the start of operation.

T In addition, the correction amount converter 45 calculates 5×ΔP and corrects the correction value δ so as to gradually increase with the passage of time, so that the correction value δ and the measurement data output from the A-D converter 41 are Since y increases while y is equal, the corrected data can be set to a small value at any point in time. Therefore, even if the limit value set in the pass/fail judgment limit setter 50 is made small, if the product is non-defective during the inspection period T3, the pass/fail limit value △P
It never exceeds s. Therefore, the pass/fail limit value Δps can be set small, and a highly accurate leak test can be performed. Therefore, the effect is extremely great in practical use.

<Other Embodiments of the Invention> FIG. 5 shows a case where the configuration of each part shown in FIG. 3 is configured by a microcomputer.

In FIG. 5, 55 indicates a microcomputer. As is well known, the microcomputer 55 can be composed of a central processing unit 56, a ROM 57, a RAM 58, an input port 59, and an output port 1. The analog measurement data of the differential pressure detector 22 is amplified by the amplifier 31, and the amplified output is connected to the input port 59.
-D converter 41 provides digital measurement data that has been A-D converted. The central processing unit 56 controls the A-D converter 4 at regular time intervals, for example, at time intervals of about 10 milliseconds.
Import the measurement data output from 1.

In addition to the A-D converter 41, the input port 59 has a setting device 62.
is connected. As explained in FIG. 3, the setting device 62 includes an error upper limit value setting device 42a, a sample number setting device 43 for calculating the average value, a pass/fail judgment limit setting device 50, and an initial correction amount setting device 53. connected to each of these setting devices 42a.
, 43, 50. The setting value set to 53 is the central processing unit 5.
6 and stored at a designated address in the RAM 58.

FIG. 6 shows a flowchart illustrating the operational sequence of the embodiment shown in FIG.

In step (2), the setting device 42a is used as described above.

4-3, 50, and 53 are loaded into the RAM 58. In step (2), the A-D conversion value is taken in.

In step (2), it is determined whether the A-D conversion value is smaller than the error upper limit value ΔPM. This judgment step (2) corresponds to the gate means 42b shown in FIG. 3, and if the A-D conversion value is larger than the error upper limit value than PM, the process jumps to step 00 and a defect signal 51'' is output.

In step (2), the A-D conversion value is loaded into the RAM 48.

In step (2), it is determined whether or not this is the first cycle of inspection. As a result of this determination, if the first time is the inspection cycle, the first correction value is read out in step (3).

If it is determined in step (2) that the test cycle is not the first one, the process jumps to step (2), where it is determined whether the number of test cycles is larger or smaller than the number N set in the sampling number setting device 43. As a result of this determination, if the number of inspection cycles is smaller than the number N set in the sampling number setter 43, the average value of the inspection data taken into the RAM 48 is calculated in step @.

In the judgment in step (2), if the number of measurement cycles is greater than the set number N of the sampling setter 43, in step 0, the previous data corresponding to the set number N is removed, a new A-D conversion value is added, and the average value is Calculate.

Using these average values or the initial correction value ΔP, calculate the upper×ΔP in the step, and convert it into a correction value δ that becomes 3 points higher with time. Therefore, this step (2) corresponds to the correction amount converter 45 shown in FIG.

In step (2), the A-D conversion value is corrected using the correction value obtained in step (2). Therefore, this step ■ is the third
This corresponds to the data correction section 47 shown in the figure.

In step (2), it is determined whether the corrected data is within the pass/fail judgment limit, and if it is within the pass/fail judgment limit, a pass signal 51 is output in step [phase]. If the corrected data exceeds the pass/fail judgment limit, jump with step lily() and send the defect signal 5.
Outputs 1°.

The above sequence operations are executed by a program stored in the ROM 57 constituting the microcomputer 55.

<Yet another embodiment of the invention> By the way, in the above description, the reference tank 21 is
The case has been described in which the pressure difference between the test object 20 and the reference tank 21 is detected by the differential pressure detector 22, but as shown in FIG. 7, only the test food 20 is pressurized or A leak testing device is also considered in which the pressure change in the test object 20 is directly detected by the pressure detector 63 without being detected as a pressure difference with the reference tank after evacuation is performed, and leakage in the test object 20 is detected based on the pressure change. It will be done.

FIG. 7 shows a case where the present invention is applied to such a leak testing device. In FIG. 7, parts corresponding to those in FIG. 5 are designated by the same reference numerals, and redundant explanation thereof will be omitted.

As explained above, according to the present invention, since the initial correction value is prepared at the time of starting operation, highly accurate leakage inspection can be performed from the time of starting operation.

Even if the error value gradually changes as the dimension inspection 111i1 cycle progresses, the correction value changes to follow the change, so that leakage inspection can always be performed with high precision even over time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining a conventional leakage test device, FIG. 2 is a waveform diagram for explaining the operation of FIG. 1, and FIG. 3 is a block diagram for explaining an embodiment of the present invention. 4 is a block diagram for explaining the correction operation in the embodiment of FIG. 3, FIG. 5 is a block diagram for explaining another embodiment of the invention, and FIG. 6 is a block diagram for explaining the operation of FIG. 5. Flowchart FIG. 7 is a block diagram showing another embodiment of the present invention. ll: Pressure source, 20: Test object, 21: Reference tank, 2
2: Differential pressure detector, 31: Zero point correction amplifier, 41: A-
D converter, 42: Storage means, 44: Average value calculation unit, 45
: correction amount converter, 47: data correction section, 49: pass/fail judgment comparison section, 50: pass/fail judgment limit setter, 53: initial correction amount setter. Agent Takashi Kusano

Claims (1)

[Claims] (1) A. An inspection means that applies a constant fluid pressure to the object to be inspected and measures changes in pressure inside or outside the object to obtain inspection data, and B. Obtains data from this inspection means. a storage means for storing a predetermined number of test takes within an appropriate range of the test data to be measured; D. Data correction means for correcting the measurement data obtained from the measurement means using the error correction value obtained by this calculation means; E. Correction corrected by this data correction means. F. a pass/fail judgment means for comparing the completed inspection data and a pass/fail judgment limit value to judge the pass/fail of the inspected object; a pressure change detection type leak test comprising: initial correction value setting means for correcting the test data of the first test cycle by giving a preset error correction value to the data correction means only in the first test cycle of operation; Device.