Technological properties of covering masses of electrode coatings

Abstract

In domestic and foreign publications the problems of quality of manufacture of coated electrodes are considered quite insufficiently. In the present work an attempt was made to consider the causes for insufficient stability of the process of molding the electrodes and to share a practical experience in their elimination. The recommendations on optimizing the coating process in the manufacture of electrodes were given. 4 Ref. K e y w o r d s : manufacture of welding electrodes, covering masses, technological properties, optimization, granulometric composition, composition and properties of chargeThe quality of manufacture of coated welding electrodes is determined mainly by technological properties of covering masses. The most significant indicator of the quality is the difference in thickness of coating. This indicator manifests itself at the stage of deposition of covering mass (coating) on rods in the process of their molding under the pressures on mass of up to 800 kg/cm 2 and at speeds of up to 400 m/min. For 90 % the stability of molding process, including the polythickness of coating, is determined by molding (plastic) properties of covering masses.It is characteristic that in the publications on this problem there are no clear regularities about the influence of different parameters and characteristics of technological components on molding properties and, moreover, there are no clear practical recommendations for technologists and manufactures.The aim of the work is to consider the causes of instability of the process of molding the electrodes and the possible ways of their elimination.Technological properties of masses. They include:• molding (plastic) properties of covering masses: pressure of molding (the lower the better at a sufficient resistance to dents), degree of stability of flows formation at the lead-in molding area and, accordingly, the stability of polythickness of coating deposition on rods at molding; the degree of mass (coating) adhesion to the rod at their contact in the molding chamber;• properties of raw masses (coating), which characterize their tendency to processing (to rupture of coating in plane of mating the rods of electrodes after coming out from the molding head), to cleaning the coating for the electrode holder and the contact end, to sticking of electrodes, sticking to the frames, etc.;• drying properties of covering masses: resistance of structure of covering masses to the passage of humidity (removal from inner layers); degree of softening the masses during heating at the initial stages of drying; tendency of masses to shrinkage and to micro/ macrocracks; to delamination from the rod surface (cracks and delamination reduce the strength of electrodes coating);• strength properties of coating of ready electrodes.Causes of low technological properties and ways of their optimization. The results of experiments, manufacturing experience and their analysis on the basis of the available scientific publications [1-4] allow stating that molding properties of covering masses are de...