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The process of brazing certain components should be carried out with the surfaces in the vertical position, in particular, components consisting of coaxial shells connected together (Fig. 1). These components are brazed using brazing alloys in the form of foil, coatings or paste, deposited on the surfaces. Heating for brazing is usually carried out in special systems, fitted with a manipulator (Fig. 2), rotating the component in relation to its horizontal central axis in order to prevent the flow of the melt of the brazing alloys and filling of the areas between the individual ribs. The need for rotating the component complicates the brazing process and restricts the possibilities of carrying out the process in shaft and bell furnaces. These shortcomings are not found in brazing with the surfaces in the vertical position, without rotating the components.
In melting of the brazing alloys in the gap of the component in the vertical position, the resultant melt is subjected to the effect of gravitational forces and capillary pressure, generated by the bent surfaces of the melt. In certain conditions, the capillary pressure may be incapable of maintaining the melt of the brazing alloy in the gap because already in the stage of development of technology, it is necessary to obtain information on the filling of the welding gap by the brazing alloy. This information may be obtained on the basis of the calculation and experimental approaches. The analysis and development of these procedures is the subject of the present work.
The standardised method of determination of the capacity of the melt of the brazing alloy to maintain its position in the vertical brazed joint (GOST 20485-75) is based on the well-known physical phenomenon of the lifting of the liquid in the gap between the vertical surfaces of the specimen, immersed in the liquid by its lower part. The earned surface of the liquid in the gap generates a capillary pressure, lifting the liquid to a certain distance above the non-perturbed surface. The value of the height, determined in this manner, is regarded as the required characteristic. The identical procedure is also used abroad.2, etc
However, experience with vertical brazing shows that in the brazed joints, the molten brazing...