SU1717982A1 - Method of seal control of hollow articles - Google Patents

Abstract

The invention relates to the monitoring of the leaktightness of products by a mass spectrometric method and makes it possible to increase the reliability of the control by eliminating the fit of the elastic shell to the surface of the product. The product in an elastic shell is placed in a vacuum chamber. Then, the vacuum chamber and the closed cavity between the surface of the product and the elastic shell are pumped out, the latter being pumped to a lower degree of vacuum than the vacuum chamber. Withstand the test article filled with the test medium for a specified time. Then the vacuum chamber is communicated with the atmosphere and the indicator device. According to the penetration of the control medium through the walls of the product, its tightness is judged. 1 il.

Description

The invention relates to a control and measuring technique, namely to the control of the tightness of hollow articles.

There is a known method for controlling the tightness of products, including filling the internal cavity of a test product with a test gas, which is preliminarily placed in a vacuum chamber and pumped out the last with a vacuum pump, and the degree of tightness of the test sample is judged by the background level of the test gas flowing from the test product Lem, and the controlled product is placed in an elastic gas-tight casing located in a vacuum chamber, which is pumped out in an elastic lawn permeable shell, then for a certain time stand the test product filled with test gas, after which the vacuum chamber is reported with the atmosphere and measured

the leak detector the background level of the sample gas in the cavity between the body of the product being tested and the elastic gas-permeable shell.

However, this method of control, due to the possibility of overlapping of places having leaktightness on a controlled product by an elastic gas-tight casing, has low reliability.

The aim of the invention is to increase the reliability of the control.

This goal is achieved by the fact that the vacuuming is carried out to a pressure in the chamber lower than the pressure in the closed cavity between the surface of the product and the elastic sheath by an amount sufficient to achieve a sheath volume greater than the product volume.

The drawing is a diagram of the device implemented by the proposed method.

The proposed method is carried out as follows.

X

h about

| s

uh

The product 1 in an elastic gas-tight casing 2 is placed in a vacuum chamber 3. After opening the valves 4 and 5, the vacuum chamber 3 and the internal cavity of the elastic gas-tight casing 2 are pumped out with a vacuum pump 6 to a degree of vacuum PI. The valve 5 is then closed and the vacuum chamber 3 is pumped out to a degree of dilution Ro PL Elastic gas-tight casing 2 under the influence of the differential pressure AP Pi-Po expands and occupies the volume V06 YD, where V06 is the volume of the internal cavity of the elastic gas-tight casing after it is pumped out and the vacuum chamber ; Ouzd - the volume occupied by the controlled product.

Close valve A. After opening valve 7, fill test item 1 with test gas from test gas supply system 8 to pressure g. After closing valve 7, test item 1 is held in the internal cavity of elastic gas-tight casing 2 for a time period t, determined requirement mi tightness controlled product 1 and calculated by the formula

„Wizd Ra / CLNG,„, P2 -P1,

tg Ж rn Р - PI

derived from solving a differential equation

AT

V,

ed

| / tag pl7ivwdt

describing the process of molecular flow of the test gas from the controlled product 1 into the internal cavity of the elastic gas-tight shell 2 through a leakage of B at the initial conditions and, where P is the current pressure in the product;

Ra - atmospheric pressure;

Mpg is the molecular weight of the sample gas;

MV is the molecular weight of air.

After the exposure time expires, valve 9 is opened and the vacuum chamber 3 is communicated with the atmosphere. The elastic gas-tight cladding 2 under the influence of the pressure difference DR Pa-P1 is compressed and occupies the volume V About V06. Then the valve 10 is opened and the level of the test gas in the cavity between the elastic gas-tight

the shell 2 and the body of the test product: 1 and the degree of the test gas is judged on the degree of tightness of the test product.

Compared with the base object, the claimed method has a higher reliability of leakage testing results when stretching an elastic gas-tight shell under the influence of pressure difference between the cavities of the vacuum chamber and the elastic gas-tight shell and, therefore, excludes the possibility of overlapping of leaks controlled product elastic gas-tight sheath.

Claims (1)

Formula invented and The method of controlling the tightness of hollow products, which consists in enclosing the elastic sheath attached to the indicator device, placing the product in an elastic sheath in the chamber, evacuating the chamber and the closed cavity between the surface of the product and the elastic sheath, filling the product with the test medium, maintaining the product at for a certain time, the pressure in the chamber is increased, and the tightness is judged by the penetration of the test medium through the walls of the product, which is recorded using an indicator device, in order to increase the reliability of the control, vacuuming is carried out to lower than the pressure in the closed cavity between the surface of the product and the elastic shell to an extent sufficient to achieve a shell volume greater than the volume of the product.