SU374504A1 - METHOD OF TESTING SHEET MATERIALS FOR DEEP EXTRACT BY ERIXEN - Google Patents

Description

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The invention relates to methods for testing thin sheet porous materials for deep drawability, i.e., methods for determining stampability in the manufacture of filters, porous parts of chemical current sources, etc.

A known method for determining stampability by the Eriksen method is that the specimen clamped on an annular matrix is pulled under load with a steam punch. According to the magnitude of the specimen deformation, its stampability is determined without destruction.

The known method, however, does not allow to determine the ability to deeply draw sheet porous permeable materials, since the appearance of trash is sometimes the result of complete destruction, and the maximum allowable changes in the porous structure during the test remain unnoticed.

The purpose of the invention is to improve the accuracy of controlling the amount of deformation of porous, predominantly metal-ceramic, materials when tested for deep drawing.

This is achieved by soaking the sample under study with a wetting fluid, pouring it over the sample, under which create an overpressure of gas, the value of which is less than the equilibrium pressure of the wetting fluid in the pores of the maximum radius of the non-deformed sample.

the moment of maximum permissible destruction of its structure is judged by the appearance of gas bubbles in the liquid.

The gas pressure on the sample impregnated with the wetting fluid and poured in from above allows to determine the value of the permissible limit of burrowing channels depending on the depth of sample drawing and the shape of the punch tip, which is based on the property of the capillary of a certain cross section to release the filling liquid if the wetting pressure the fluid in the channel is less than the external pressure of the gas.

The drawing shows schematically the installation for the implementation of the proposed method.

The sample / porous cermet material to be tested, impregnated with a wetting fluid, is attached to the annular matrix 2. Pa sample the layer 3 of the same liquid. In the hermetic chamber 4, a gas pressure is created through the regulator 5 from the gas cylinder 6, controlled by a pressure gauge 7. In the hermetic chamber there is a mechanism for the uniform movement of the punch 8, which creates a deformation force of the sample.

With a uniform strain rate, there will come a time when individual pores will increase in cross sections due to the strain in the stretch zones, therefore the equilibrium pressure in the deformed pores will be less than the recorded gas pressure in the sealed chamber. The gas bubbles through the released pores will be observed in the liquid layer, therefore, the structure of the porous sample is broken beyond the allowable limit. By knowing the amount of deformation at the moment of occurrence of bubbles and the amount of pressure in the chamber, it is possible to judge about the possibility of stretching the test material taking into account the permissible values of violation of the porous structure. Method of the Invention A method of testing sheet materials for deep drawing according to Eriksen, which consists in fixing the sample under test on an annular matrix, applying a load to it by means of a ball-shaped indenter punch, and deforming the sample until the maximum permissible destruction of its structure is judged The ability of the material for deep drawing, characterized in that, in order to increase the accuracy of controlling the amount of deformation of porous, mainly cermet, materials, the sample under study is They are moistened with a wetting liquid, poured over the sample, under which they create an overpressure of gas, the magnitude of which is less than the equilibrium pressure, is wetted with it in the tubes of the maximum radius of the non-deformed sample, and the appearance of gas bubbles in the liquid is judged .

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