SU1733934A1 - Method of testing watch for tightness - Google Patents

Abstract

The invention relates to the control of clocks for leaks and improves reliability and accuracy. The watch is kept in the chamber at a certain excessive air pressure, and the humidity and temperature of the air are determined in the chamber. Before keeping the clock in the chamber, the clock is checked for condensation by cooling the heated glass by repeatedly applying a certain dose of water to the surface of the heated glass. The temperature of the water decreases with a step difference of arithmetic progression. The temperature of the cooling water ti is determined at which condensation starts at a given dose of water. The clock is checked for condensation through similar operations by changing the dose of cooling water, and the temperature of cooling water t2 at which condensation starts is determined at the new value of the dose of water. The dew point tp is determined by the values of ti, t2 and the dose ratio of cooling water. Similarly, the dew point is determined before keeping the clock in the chamber. The mass of air that entered the clock through leaks is determined by taking into account the dew point values. It is also possible to heat them up with the lid removed before setting the clock in the chamber, and to install the lid after drying. 1 h.p.fly. SO with

Description

The invention relates to metrology and can be used in the watch industry in the manufacture of waterproof watches.

There is a known method of controlling the tightness of a clock, based on the fact that, under conditions of excessive air pressure, no more than 50 µg / min should penetrate into the clock at 2 bar

(one).

A known method of controlling the tightness of a clock is by checking the hours for condensation by setting the clock to a certain temperature and cooling the heated glass of the water clock hey with a temperature of 18-25 ° C and fixing the presence or absence of condensation moisture on the glass, immersing the clock into water to a certain depth for a fixed period of time and re-check hours for condensation through similar operations (1).

The disadvantage of this method is low reliability and accuracy.

The aim of the invention is to increase reliability and accuracy.

The goal is achieved by maintaining the humidity and air temperature in

VI

00

with cho with

In the chamber, the watch is checked for condensation. During both hours of condensation testing, the heated glass is cooled by repeatedly applying a certain dose of water to the surface of the heated glass, the temperature of which decreases with an arithmetic progression step and the cooling water temperature ti at which the condensation starts at that dose of water is repeated. checking the hours for condensation through similar operations, changing the dose of cooling water, and determining the temperature of the cooling water t2 at which condensation begins m value of the dose of water and determine the dew point tp by the values of ti, t2 and the ratio of doses of cooling water, similarly determine the dew point before keeping the clock in the chamber and determine the mass of air that penetrated into the clock through leaks, taking into account the values of dew points that, before keeping the clock in the chamber, they are subjected to heat drying with the cover removed, and the cover is set after drying is completed.

The essence of the invention is as follows.

Before placing the clock in a chamber with excess pressure of moist air, they are subjected to a condensation test. For this, the clock is heated to a certain temperature by placing the clock, for example, in a thermostat. The clock is then removed from the thermostat and the heated glass is cooled with a fixed mass of water mi. The latter is carried out by, for example, a glass tube with a calibrated orifice, into which a column of water of a certain height is drawn. When the watch is first checked for condensation, the cooling water temperature is chosen to be 25 ° C. If during the test there is no condensation moisture on the glass, then they are often again subjected to heating to the same specific temperature. Then again, the heated glass is cooled with water of mass mi with a temperature which is reduced by the difference of the arithmetic progression. In the absence of condensation moisture, with a new lower value of the cooling water temperature, the hours are again heated and the heated glass is cooled with water of a mass of IHR. However, the water temperature is again reduced by the difference of the arithmetic progression. This repeated process of heating and cooling the clock, in which the water temperature decreases with a step difference of arithmetic progression until the condensation moisture deposits on the glass. This completes the hours check for condensation, and the cooling water temperature ti is recorded at which the condensate is wilted. This ti value is the upper limit of the temperature range of the cooling water of mass mi, causing the appearance of condensate. At lower temperatures, cooling water, other things being equal, condensate will always appear.

Then, the watch is checked for condensation by similar operations, replacing the value of the mass of water in the GHz with that. During the watch’s check for condensation, the temperature of cooling water t2 is determined at which the condensate is cooled by cooling the heated glass with water of mass t2.

When checking clocks for condensation in both cases, it is necessary to ensure that the area of water-cooled glass areas is the same. Under this condition, the value of the total dew point condensation test tp1 for both cases is determined by the expression

TP1

mit1 - ITI2t2

mi - rri2

The calculated dew point tp- | characterizes the moisture concentration in the air hours and thereby determine the moisture content in hours before testing them in the chamber and excess moist air.

However, this condensation test to determine the moisture in the air of a watch can be excluded if the watch with its cover removed is subjected to heat drying. This operation makes it possible to reduce the value of the moisture concentration in the air of the watch to such a value that it can be neglected later on. At the end of the heat drying, the closure of the clock is quickly performed.

After completion of the preliminary condensation test or heat-drying, the watch is placed in a sealed chamber of constant volume. For a fixed period of time, a certain excessive air pressure of a certain humidity and temperature is created in the chamber.

The clock is then removed from the chamber and subjected to a condensation test, carried out through similar operations. During this test, the dew point value tP2- is determined. From the calculated values tpi and tP2, the maximum humidity values fmaxi and fmax2 are determined from the directory for temperatures tpi and tP2. Then the air mass of the TV that penetrated into the clock while in the chamber with excess pressure is determined by the expression

. . fmax2 fmaxi tv 1p ---

Ttakh f

where V is the volume of the inner part of the air-filled hours;

p is the density of air in hours;

fmaxK is the maximum air humidity in the chamber for a given air temperature;

p is the value of the relative humidity of the air in the chamber.

In the case of heat drying of the clock in the expression for TV, the value of fmaxi is taken to be zero.

Claims (2)

Claim 1. Method of monitoring the tightness of a clock by keeping the clock in the chamber at a certain excessive air pressure, checking the clock for condensation by heating the clock and cooling the heated glass of the clock with water not exceeding 25 ° C and fixing the presence or absence of condensation moisture on the glass, differing in order to to increase the reliability and accuracy, when keeping the clock in the chamber, the humidity and air temperature in it are determined, before keeping the clock in the chamber, the clock is checked for condensation, the heated glass is cooled during both checks of the condensation clock by repeatedly applying heated glass to the surface a certain dose of water, the temperature of which decreases with a step difference of arithmetic progression, and determine the temperature of the cooling water ti, at which condensation begins at a given dose of water, repeat the condensation hours test by similar operations, changing the dose of cooling water, and determine the temperature of the cooling water t2 at which starts condensation at a new dose of water, and determine the dew point tp by the values of c, t2 and the dose ratio of cooling water, similarly determine the dew point after keeping the hours in the chamber and determine the mass of air that penetrated into the clock through leaks, taking into account dew point values. 2. A method according to claim 1, characterized in that before keeping the hours in the chamber, they are subjected to heat drying with the cover removed, and the cover is installed after drying is completed.