SU1469372A1 - Method of testing air-tightness of closed hollow articles - Google Patents

Description

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The invention relates to a test technique and permits monitoring of compact closed hollow articles, preferably cases of wrist and pocket watches, for tightness.

The aim of the invention is to increase the reliability of control of products of various dimensions by creating the same test conditions for all sizes of products.

The drawing shows a diagram of the device for implementing the method.

The device comprises a case 1 made of a material having good thermal conductivity, for example of brass, and having two hermetic chambers 2 and 3: a working one, where a controlled watch 4 is placed, and a reference one. The working chamber 2 is closed by a bolt 5 through a hermetic gasket 6. Both chambers 2 and 3 are insulated from each other by a fixed partition 7, in which a channel 8 is made, which connects the working chamber 2 to the internal volume of the bellows 9 fixed on the partition 7 and located in the reference chamber 3

On the bellows 9, a movable element of the differential inductive sensor 10 is fixed, which converts the pressure difference i p.

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between chambers 2 and 3 to ac frequency. The control values of the differential pressure LR during the measurement cycle are memorized, microprocessor-based computing device and compared with each other.

The working chamber 2 has a channel 11 connecting it with an additional bellows 12 located tO outside the housing 1 and intended to compensate for measurement errors resulting from changes in the volume of the working chamber 2 when testing different-sized clocks. 15 The compression of the bellows 12 is effected by means of the metered movement mechanism 13.

Chambers 2 and 3 are connected via pipe 14 to test pressure source 20-15 and communicate with each other.

The valve 16 serves to disconnect the chambers 2 and 3 from the source 15. The initial (initial) differential pressure LR between chambers 2 and 3 is recorded and stored by a microprocessor-based computing device. As a rule, 4P, in real terms, is different from zero.

After separating chambers 2 and 3 and measuring 4P, the metered displacement mechanism 13 compresses the sylphon 12 by a predetermined value. In this case, a volume of air is displaced from the bellows 12 into the chamber 2, which is equal to the product of the maximum permissible leakage by the exposure time. According to the existing standards, the maximum permissible leakage is 50 µg / min at a pressure of 2 atm. As a result of the compression of the bellows 12 by the indicated amount, the initial volume of the working chamber 2 decreases, and the pressure in it increases inversely with its working volume, which depends on the dimensions of the pressure and 17 and 18, 25 gauge 2 products 4, t. e. the more pipelines 4 that are installed in the branches, the greater will be the pressure in chamber 2. As a result,

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wires 14 are designed to separate the working and reference chambers 2 and 3.,

A method for monitoring the tightness of closed hollow articles is performed 30 as follows.

In the working chamber 2 is placed a controlled watch case 4 and tightly close it with a lid 5. The gasket 6 ensures the tightness of the working chamber 2.

Further, air from source 15 under pressure is simultaneously supplied through conduit 14 to chamber 0 and 2 simultaneously. After pressure in chambers 2 and 3 reaches a test value of 2 atm, chambers 2 and 3 are disconnected from source 15 of pressure by means of valve 16, and some time required to equalize the temperature in chambers 2 and 3, they are separated from each other, valve 17

and 18.

In this case, as a result of the inevitable errors in the manufacture of the device and the asynchronous closing of the valves 17 and 18, some random pressure difference occurs in chambers 2 and 3, Since chambers 2 and 3 are connected between

2. As a result of the bellows 12, a change in pressure in chamber 2 causes a change in pressure differential / 5 P between chambers 2 and 3, which actuates the syringe 9 and the movable element of sensor 10. The microprocessor device immediately fixes the new value of pressure drop 4 and compares it with the calculated /) RF, previously stored in the memory of the microprocessor device when testing a sealed product 4 of the smallest size. Comparison of 4Pp pressure drops allows us to reveal product 4 with a clear:; Leakage, which is an order of magnitude higher than acceptable. When AV Pf product 4 is discarded, their further testing is terminated. If LR is -7 / PP, product 4 continues to be tested for a predetermined period of time, for example, for 1 min.

After the specified time has elapsed, the final differential pressure Rp in chambers 2 and 3, which is compared with the initial differential pressure LR, and negative negative difference sign are measured again. . -.

background 9, it reacts to the initial pressure drop between chambers 2 and 3, which causes movement of the movable element of the sensor 10.

Tests for leakage of the controlled article 4 with respect to the maximum permissible leakage. If the AP is c- - DP / 0, item 4 has a tolerance. The initial (initial) differential pressure LR between chambers 2 and 3 is recorded and stored by a microprocessor-based computing device. As a rule, 4P, in real terms, is different from zero.

After separation of chambers 2 and 3 and measurement of 4P, the force of background 12 compresses the force of background 12 by a predetermined amount. When this occurs, a volume of air is displaced from the bellows 12 into the chamber 2, which is equal to the product of the maximum permissible leakage by the exposure time. According to the existing standards, the maximum permissible leakage is 50 µg / min at a pressure of 2 atm. As a result of the compression of the bellows 12 by the indicated amount, the initial volume of the working chamber 2 decreases, and the pressure in it increases inversely with its working volume, which depends on the dimensions of the product 4 placed in the working chamber 2, i.e. the larger of division 4, the greater will be the pressure in chamber 2. As a result of compression

Here 2 products 4, i.e. the greater the amount of 4, the greater the pressure in chamber 2 will increase. As a result,

2. As a result of the bellows 12, a change in pressure in chamber 2 causes a change in pressure differential / 5 P between chambers 2 and 3, which actuates the syringe 9 and the movable element of sensor 10. The microprocessor device immediately fixes the new value of pressure drop 4 and compares it with the calculated /) RF, previously stored in the memory of the microprocessor device when testing a sealed product 4 of the smallest size. Comparison of 4Pp pressure drops allows detecting product 4 with a clear:;: leakage, which is an order of magnitude higher than the permissible value. When Pf product 4 is rejected, their further testing is terminated. If LR is -7 / PP, item 4 continues to be tested for a specified period of time, for example, for 1 minute.

After the specified time has elapsed, the final differential pressure iR in chambers 2 and 3, which is compared with the initial differential pressure LR, is again measured, and by the negative sign of the difference

Tests for leakage of the controlled article 4 with respect to the maximum permissible leakage. If the AP is c- - DP / 0, item 4 has a permissible degree of leakage, and if RC -JP, O, the degree of leakage of item 4 is equal to the maximum permissible leakage (50 µg), and at 1Pc - LR0, the item is unpressurized and rejected.

In this case, the differential pressure / 5P between both chambers 2 and 3 is considered positive if the pressure in the working chamber 2 is greater than the pressure in the reference chamber 3.

Thus, a metered reduction in the volume of the working chamber 2 after the test pressure is applied to

the value equivalent to the maximum permissible leakage allows, in the results, the measurement to take into account changes in the volume of the working chamber 2 with the product 4 when testing differently sized products, to provide the possibility of a rough rough determination of the degree of leakage of products 4 in order to reveal their obvious leakage and exclude the possibility get them in fit.

All this ensures the accuracy and, therefore, the reliability of the control of products for tightness.

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Editor A. Dolinich

Tehred M. Khodanych

Order 1351/48 Circulation 788 Subscription

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab., 4/5

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Proofreader V. Girn to

Claims (1)

METHOD FOR SEALING CLOSED ENCLOSED ITEMS by placing the product in a working chamber, creating a test pressure in the working and reference chambers by communicating them with a source of compressed gas, measuring the initial pressure drop between the working and reference chambers after they are disconnected from the compressed gas source, measuring the final pressure drop between them