METHOD OF PREPARING ROLLS OF TUBE-ROLLING MILLS FOR OPERATION Russian patent published in 2010 - IPC B21B28/02 

FIELD: metallurgy.

SUBSTANCE: method involves mechanical treatment of the working surface of roll press, welding of wear-resistant heat-resistant layer with allowance for mechanical treatment and mechanical treatment for finished size till surface roughness of not more than 6.5 mcm Ra is obtained. Improvement of the quality of tube surface, reduction of their wall thickness variation, improvement of wear resistance of rolls is provided owing to further application (in 1-2 passes) of additional wear-resistant layer by means of electric spark alloying method at which between the roll surface and hard-alloy tool electrode the spark discharges appear in the form of flow of electrons, thus providing saturation of the treated surface with tool electrode material. At that, the roll rotates with frequency of 2-5 min^-1, and tool electrode moves linearly with supply 0.1-0.5 mm/rev, thus repeating the roll pass profile. Coating with thickness of wear-resistant layer of 50-150 mcm, micro-hardness of 1000-1800 kilogauss/mm² and isotropic microrelief with roughness of not more than 25 mcm Ra is obtained at currents of spark 10-30 A with voltage amplitude of 40-90 V and cooling air flow of 0.4-0.5 m³/min. Additional layer can be applied for many times.

EFFECT: improving the quality of items of tube surface, reducing wall thickness variation and increasing operating lifetime of rolls.

2 cl