SU1548678A2 - Method of testing hollow articles for tightness - Google Patents

Abstract

The invention relates to the monitoring of the tightness of closed hollow articles and allows to increase the reliability by excluding the pass as suitable products with a coarse leak. The products are installed in a vacuum chamber, the last vacuum. At the same time, the products are heated to a temperature selected from the condition that the pressure changes from the gas temperature expansion to the pressure change in the product from the permissible leakage under vacuum conditions. After the exposure time, let in atmospheric air into the chamber. By measuring the deformation of the walls of the product 1, the tightness of the product 2 is determined. 1C. f-ly, 1 ill.

Description

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The invention relates to a test technique, allows the controlled tightness of closed hollow articles and is an improvement of the known method according to the author. No. 1267190.

The aim of the invention is to increase the credibility by eliminating the pass as fit products with coarse leaks.

The drawing shows a diagram of an apparatus for implementing a method for testing hollow articles for tightness.

The device comprises a vacuum chamber 1, inside of which monitored products 2 are placed, a vacuum device 3 connected via valve 4 to a vacuum chamber 1. Inside the vacuum chamber there is a heater 5, and outside the vacuum chamber 1 there is a sensor 6 for measuring the deformation of the walls of the products 2. Vacuum chamber 1 through valve 7 is connected to the atmosphere. A vacuum gauge 8 is provided for monitoring the vacuum in chamber 1, and a temperature sensor 9 is used to monitor the temperature.

The method for testing hollow articles for leaktightness is implemented by the following method.

A mark is applied on the surface of the product 2 at the location where the deformations of the walls of the product 2 are measured. Using the sensor 6, the dimensions of the product 2 are measured at the places of the marking settings. The articles 2 are placed in the vacuum chamber 1. The valve 4 is opened and, with the help of the dilution means 3, vacuum is created in the vacuum chamber 1 and at the same time the products are heated by means of the heater 5.

As a result of the temperature expansion of the gas in each test article 2, the pressure is changed by an amount determined by the following formula:

 - one)

J- 1

(one)

Where

Pu gas pressure in the cavity of product 2 at normal temperature;

T t and T is the temperature of the product, respectively, normal and under vacuum. In the process of aging in the conditions of |

vacuum gas pressure in the cavity

item 2 is changed by a value defined by the following formula:

-Ґ-

(2)

Where

Q

V

the amount of leakage in the product under vacuum conditions; volume of product 2 filled with gas; Ј - holding time of product 2

sparse conditions. From the condition of equality of expressions (1) and (2), an expression is obtained for determining the temperature to which product 2 should be heated in the process of creating a vacuum:

(9JL

PH-V

+ 1)

(3)

Where

Q a - acceptable value of the leak in the product,

those. The heating temperature of the product 2 is selected from the condition of the equality of the pressure change from the temperature expansion of the gas to the pressure change in the product 2 from the allowable leakage under vacuum conditions. The pressure in the vacuum chamber 1 is controlled by the vacuum gauge 8, and the temperature of the products is 2nd by using the sensor 9. The products 2 are kept under vacuum conditions and the set temperature for the time required to detect unacceptable microdensity in the products 2. Then the pressure in the vacuum chamber is increased 1 to atmospheric, opening the valve 7. Take out the product 2 from the vacuum chamber

1 and measure the size of each item.

2in the places of the set marks using the sensor 6. In the absence of deformation or, if the deformation has a negative value, product 2 is rejected. Product 2 is considered suitable if the deformation is positive.

The method of testing hollow articles for leaktightness allows to increase the reliability of the tests due to the fact that the omission of coarse leaks is excluded and the accuracy of measurement of the amount of deformation of the walls of the product is improved. The productivity of the testing process increases, since the creation of a vacuum, the exposure of products under vacuum conditions and the rise in pressure to atmospheric values are not consistently performed.

each item tested, and for a group of items. The operating time of expensive vacuum equipment is also reduced.

Claims (2)

1. Method for testing hollow articles for leak tightness according to ed. St. No. 1267190, characterized in that, in order to increase the credibility by excluding a pass in quality of products with a coarse leak; simultaneously with the creation of a vacuum, the product is heated to a temperature selected from the condition that the pressure is equal to the temperature expansion of the gas and the pressure in the product varies from the allowable leak under the vacuum conditions. 2. The method according to claim 1, characterized in that the deformation measurement of the walls of the product is carried out outside the vacuum chamber.