EFFECT OF THE PROPERTIES OF GLASS-LUBRICANTS ON THE PROCESS OF PRESSING PIPES FROM STAINLESS STEEL 08Cr18Ni10Ti
The article presents the results of the investigation of the influence of the particle size of the glass greases and the viscosity of their melts on the pressing process. When pressing the pipes to reduce stress, glassmaking is used in the form of a powder, which at the pressing temperature forms a melt on the contact surface of the deformable metal with a press tool, resulting in a reduction in the coefficient of friction and reduction of the pressing forces. During pressing, the frictional conditions on the contact surfaces are not the same, therefore, different glass lubricants are used in practice for the needle contacting the inner surface of the liner, the container and the matrix in contact with the outer surface of the sleeve. Viscosity and fusibility are important indicators of glass greases, which characterize the rate of softening of the glass and the formation of a melt with a certain thickness and strength. Therefore, one of the main requirements for glazing is its granulometric composition, and the resulting melt is a viscosity. Both indicators determine the efficiency of the resulting lubricating layer, which can reduce the pressing forces and ensure a good surface quality of the pipes produced. In this connection, the influence of the particle size distribution and the viscosity of the glass grease on the pressing forces of stainless steel pipes 08Cr18Ni10Ti were studied. Tests were carried out in conditions TPTS-2 of JSC “VTZ” when pressing pipes made of steel 08Cr18Ni10Ti on a press with a force of 2000 tons. During the tests of the experimental compositions of the glass blanks, the temperatures of the liners on the glass-lubricating table were recorded and the force diagrams were used to determine the maximum force during the filling of the deformation center during pressing (peak force), as well as the average force that occurs during the steady-state stage of the pressing process. The analysis of the obtained data made it possible to draw a conclusion about the effect of the properties of the glass lubricant on the peak and average pressing force in different temperature intervals.