SU1673888A1 - Method for quality control of thermos flasks - Google Patents

Abstract

The invention relates to the production of thermos flasks and allows to simplify the process of quality control of flasks of thermos flasks. During the manufacturing process, the self-resonant frequency of the test bulb is measured before flushing it F ₁ . After evacuation, the control flask is maintained for a predetermined period of time, after which its own resonant frequency is measured in the evacuated state of F ₂ . The quality of the monitored bulb is judged by exceeding by the ratio F ₁ / F _{2 the} measured values of the resonant frequencies of a given threshold value equal to 1.022 - 1.032.

Description

This invention relates to methods for controlling the quality of glass flasks of thermos flasks from the point of view of their heat insulating properties.

The purpose of the invention is to simplify the method.

The essence of the method is as follows. The degree of pumping out of the wall space determines the quality of the flask, since the residual gas pressure is proportional to the value of the thermal conductivity coefficient. On the other hand, each physical body has its own resonant frequency, the value of which depends on the geometric dimensions, body mass and stiffness.

During the production of flasks, there is a variation in the wall thickness of the flasks, so the resonant frequency from flask to flask will be different, equal to fi. After evacuation, the pressure inside the flask changes. Due to the rarefaction, the intensity of the walls of the bulb increases, the natural frequency decreases and stops at f2.

If according to the measurement results we calculate the relative resonant frequency fi / f2, then this value will characterize the thermal properties of the bulb (its quality), regardless of the wall spread. After pumping, the geometrical dimensions and mass remain unchanged, therefore, taking into account the frequency ratio, we achieve the elimination of the influence of the variation in the wall thickness of the flasks.

The intrinsic resonant frequency of the flask before pumping fi and after pumping h is determined by one of the known methods.

The permissible level of the relative frequency fi, which corresponds to the minimum allowable temperature, as experiments have shown, is 1.022-1.032.

For the implementation of the method, the sequence of operations for measuring the intrinsic resonant frequency of the flask is of fundamental importance. It is impossible to determine the change in the resonant frequency

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Claims (1)

inverse sequence. Formula of Invention Along with this technological process pumping out flasks provides for their skimming living by heating, in connection with which for thermoses, which includes shutting down the supply of reliable data of a measured flask during a given resonance frequency, it is necessary for the number of time to cool to room temperature. that in order to simplify the way It is known that when heating any inversion, the natural frequencies of the resonance are measured; gas is separated, and the controlled flask is subjected to natural oscillations. As a result, in the evacuated volume, the pressure 10, respectively, before the gas is pumped out of its interspecific and the measured over-night space — fi and after the evacuation flow rate at elevated gas temperatures and controlled flask exposure to takes steady-state value only for a predetermined period of time after holding the flask for a given time in the open state fa, and about the quality go time span. Exposure after 15 controlled flasks are judged by over-pumping is also important from the point of view of the evaluation of the quenching ratio by the ratio fi / f2 measured flask taps, because it allows the values of the resonant frequencies of a given record the flow into the flask of an atmospheric threshold value of 1.02-1.032. ferric air.