JPH0134333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic error correction leakage inspection device that can automatically correct errors in detected data caused by measurement atmosphere and the like.

A product or part that must be free of fluid leakage during use is sequentially inspected during its production process line, and the inspection data is compared with set standard values to determine the quality of the product or part. is being carried out.

FIG. 1 is a block diagram showing the configuration of this type of leak testing device, in which a flow pipe 10 connected to the output side of a pneumatic pressure source 11 is connected to the outlet side of the solenoid valve 14 via a pressure regulating valve 12 and a solenoid valve 14. Branching road 15-1, 1
5-2, respectively. A pressure gauge 13 for setting a test pressure is connected between the outlet side of the pressure regulating valve 12 and the inlet side of the electromagnetic valve 14.

The branch 15-1 connects to the conduit 18 via the solenoid valve 16.
A mechanism is provided at the other end of the conduit 18 to which an object 20 to be inspected for leakage can be connected. A mechanism at the other end of the conduit 18 connects the objects 20 to be tested one after another, so that a leakage test can be performed. On the other hand, the branch path 15-2 is also connected to one end of the conduit 19 via the solenoid valve 17, and the reference tank 21 is connected to the other end of the conduit 19. At the outlet sides of the electromagnetic valves 16 and 17, conduits 18 and 19 are extended and taken out, respectively, and a differential pressure detector 22 is installed between their respective ends.

The output signal of the differential pressure detector 22 is given to a comparator 32 via an amplifier 31, and the comparator 32 is configured to be able to compare it with the output reference value of the reference signal setter 33.

The object to be inspected 20 is attached to the end of the conduit 18, a leak-free reference tank 21 is attached to the conduit 19, the solenoid valve 14 is closed, the pressure regulating valve 12 is opened, and the pressure gauge 13 is used to detect the air pressure source 11. Adjust so that the specified air pressure is obtained. The solenoid valves 16 and 17 are opened, and the solenoid valve 14 is opened to send air at a constant pressure to the branch paths 15-1 and 15-.
2. Test object 2 through conduits 18 and 19, respectively.
0 and reference tank 21.

After a certain period of time has passed and the pressures in the test object 20 and the reference tank 21 have stabilized, the solenoid valves 16 and 17 are closed. Further, after a predetermined stabilization time, the automatic zero correction amplifier 3 is connected to the differential pressure detector 22.
1 output signal is read. When the inspection object 20 is completely airtight and there is no leakage,
Ideally, the output signal from the amplifier 31 becomes zero during constant detection. When there is a leak in the test object 20, an output signal is obtained that gradually decreases when the internal pressure is positive, and gradually increases when the internal pressure is negative, and the output signal within a certain detection time is either negative or positive. The value is almost proportional to the amount of leakage.

The reference signal given from the reference signal setter 33 and the output signal of the amplifier 31 are compared by the comparator 32,
A quality determination output 35 indicating whether the product is good or defective is obtained depending on whether the output signal does not exceed the reference signal.

In this conventional leakage testing device, even if the reference tank 21 is exactly the same shape as the test object 20 and has no leakage, the test object 20 and the reference tank 21
An ideal state of zero output signal cannot be obtained because of the influence of factors such as temperature, internal capacity, slight deformation distortion of shape, and difference in attached moisture. In other words, due to these factors, even if there is no leakage at all in the inspected object 20, the output signal during a certain detection time will not be in the ideal zero state, but will have a value comparable to a significant amount of positive or negative leakage. This is usually shown.

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

In addition, deformation of the rubber that seals the opening of the inspection object 20 may occur, and based on these factors, when leakage inspection is performed one after another on a large number of inspection objects 20 flowing through the production process line, it is necessary to Errors based on these factors change during the day, from day to day, or seasonally and over time.

Therefore, in the conventional leakage testing device, there is an error based on factors that change over time, and it is necessary to frequently change the output reference value of the reference signal setting device 33. 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.

This invention solves the problems with the conventional leakage testing device described above, and automatically corrects for changes in factors within a predetermined period without depending on variations in the inspected object itself, thereby always maintaining a constant testing accuracy. The purpose of the present invention is to provide an error automatic correction leakage inspection device that is capable of automatically correcting errors.

According to this invention, a constant fluid pressure is applied to the object to be inspected, and the pressure change of the object to be inspected is measured over time, or the differential pressure change between it and a leak-free reference tank to which a constant fluid pressure is applied is measured. In a leak test device that determines the quality of the inspected object by comparing it with a preset standard judgment value based on time,
A storage means is provided for storing a predetermined number of detection data of inspection objects determined to be non-defective. Further, a calculation means for calculating the average value of the detection data stored in the storage means is provided, and the average value obtained by the calculation means is used as a correction value for the detection data of the object to be inspected, and the correction value is obtained based on this correction value. A correction means for correcting the detected data is provided.

The automatic error correction leakage inspection device of this invention will be described below.
The embodiment will be described in detail with reference to the drawings.

FIG. 2 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
The input end of converter 41 is connected. The output terminal of this A-D converter 41 is connected to the input terminals of an output display 48 and a comparison section 49 via a data correction section 47 .

On the other hand, the output end of the A-D converter 41 is connected to the input end of the error data storage section 42, and the input end of the average value calculation section 44 is connected to the output end of the error data storage section 42. The output end of 44 is connected to the input end of correction amount converter 45 .

The output end of the correction amount converting section 45 is connected to a data correcting section 47 via a correction on/off switch 46. The output signal from the sampling number setter 43 can be supplied to the error data storage section 42, and the comparison section 4
9, the configuration is such that an output signal can be supplied from the tolerance value setter 50.

Generally, the amount of leakage from many products in a production process line is often completely zero for non-defective products, and the defective rate is less than a few percent. Under such conditions, it is assumed that the leakage testing device according to the present invention is installed in a production process line that continuously measures a large number of products, and is measuring a certain object to be inspected 20-i.

The output of the differential pressure detector 22 is output to the automatic zero correction amplifier 3.
1 as an input, and when an automatic zero correction signal 34 is further applied at the same time as the start of detection, the zero point is automatically corrected in the amplifier 31 and a differential pressure change output signal is obtained. This output signal is sent to the A-D converter 41
A/D conversion is performed at , and a digital output signal is obtained as measurement data indicating the differential pressure change output value ΔPi during the detection time.

At this time, if the object to be inspected is a good product, most of the value of ΔPi can be regarded as the error output Ei. When the inspected object is a defective product, ΔPi is not entirely due to leakage and often includes a considerable error Ei, but the value of the error Ei has many factors that vary slowly over time.

Therefore, as shown in FIG. 3, going back from the previous measurement of the inspected object 20-i, measurement data ΔP ₁ , ΔP ₂ , . . .
...ΔPn is regarded as error data E ₁ , E _{2 ,} . n(E ₁ +E ₂ +...+En) is calculated.

Note that the number of samples n is set to the optimum number by the sample number setter 43 in consideration of the temporal trend of the error output. In this way, the immediately preceding average error data Ei of the inspected object 20-i can be regarded as the most reliable correction amount for the measured data ΔPi of the inspected object 20-i.

Therefore, the output signal Ei from the average value calculation unit 44 is sent to the data correction unit 47 via the correction on/off switch 46, and the value ΔPi−Ei is subtracted from the measurement data ΔPi, which is output and displayed as more accurate measurement data with error compensation. displayed on the display 48. At the same time, this measurement data is given to the comparator 49 and compared with a pass/fail determination tolerance value ΔP ₀ set in the tolerance setter 50 to obtain a pass/fail determination output signal 51.

Although the correction on/off switch 46 is normally turned ON, it can be turned OFF at any time and used to check the magnitude of the error output signal in a non-defective inspected object. Furthermore, although the embodiment has shown a differential pressure detection method in which the pressure of the object 20 to be inspected is compared with the pressure of the reference tank 21, it is equally applicable to a method in which pressure is applied only to the object 20 to be inspected. Further, the electronic circuit section of the automatic error correction/leakage inspection apparatus of the present invention shown in the embodiment can be easily constructed using various LSIs (microcomputer chips, etc.).

As explained in detail above, according to the present invention, in continuous leakage inspection in a production process line,
Fluctuations in the output value for each leakage test caused by temporal changes in atmospheric conditions such as air supplied to the test object, temperature, and humidity, as well as changes in various factors such as the temperature of the jig and the deformation of the airtight seal. It is possible to obtain a measurement output that corrects for the temporally gradual fluctuations, which are most of the elements. In this manner, according to the present invention, it is possible to provide an automatic error correction leakage inspection device that performs highly accurate pass/fail judgment and performs leakage inspection of objects to be inspected in a production process line.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of a conventionally used leak testing device, FIG. 2 is a diagram showing the configuration of an embodiment of the automatic error correction leak testing device of the present invention, and FIG. 3 is a diagram illustrating the principle of the present invention. FIG. 11: Air pressure source, 20: Test object, 21: Reference tank, 22: Differential pressure detector, 31: Amplifier, 32:
Comparator, 33: Reference signal setter, 42: Error data storage section, 43: Sampling number setter, 44:
Average value calculation section, 45: Correction amount conversion section, 47: Data correction section, 48: Output display, 49: Comparison section.

Claims (1)

[Claims] 1. Apply a constant fluid pressure to the object to be inspected and capture the pressure change of this object over time, or measure the change in differential pressure between it and a leak-free reference tank to which the constant fluid pressure is applied over time. By comparing with the standard judgment value set in advance in the judgment means,
In the leak testing device for determining the quality of the inspected object, the storage means stores a predetermined number of detection data of the inspected object determined to be non-defective starting from the previous measurement of the inspected object; a calculation means for calculating the average value of the detection data stored in the calculation means; and a calculation means for calculating the average value of the detection data stored in the calculation means; and a calculation means for calculating the average value of the detection data stored in the calculation means; An automatic error correction/leakage inspection device comprising a correction means for correcting data and supplying the corrected data to the determination means.