METHOD FOR PIERCING INGOTS AND BILLETS OF TITANIUM BASE ALLOYS TO SLEEVES IN SKEW ROLLING MILLS Russian patent published in 2007 - IPC B21B21/00 

FIELD: rolled tube production, namely method for piercing ingots and billets of titanium base alloys to sleeves in skew rolling mills, possibly production of conversion tubes of large and mean diameters from ingots and billets of titanium base alloys in tube rolling aggregates including skew rolling mills, for example in tube rolling plants with pilger mills.

SUBSTANCE: method comprises steps of piercing at different revolution numbers of working rolls, namely from time moment of biting ingots and billets between rolls till time moment of full putting onto mandrel, gradually increasing revolution number of rolling rolls from n₃ till n_max; performing stable piercing process till time moment when rear end of ingot or billet achieves front end of piercing cone at maximum revolution number of working rolls n_max limited by maximum load of rolling mill drive unit and then till outlet of sleeve from piercing cone gradually decreasing revolution number of working rolls till minimum value n₃. Values of working roll revolution number during piercing cycle at i-time moment are determined according to given expression: P₃/n₃ = P_max /n_max =P_i/n_i = P_p/n_p where P₃ - load of working roll drive of piercing mill at biting ingot or billet between rolls, kA; n₃ = 28 - minimum value of revolution number of working rolls of piercing mill at biting ingot or billet between rolls, rev/min; P_max = 7.5 - maximally admissible load of drive unit of working rolls of piercing mill, kA; n_max = 50 -maximum value of working roll revolution number of piercing mill under load 7.5 kA, rev/min; P_p - load of working rolls drive in piercing mill at time moment of deformation region release, sleeve outlet from rolling out cone, kA; n_p - revolution number of working rolls of piercing mill at time moment of sleeve outlet from deformation region, rev/min; P_i - current value of load of working rolls drive of piercing mill at i-time moment of piercing cycle, kA; n_i - current value of working roll revolution number in piercing mill at i-time moment of piercing cycle, rev/min. Invention provides lowered by 15 - 20% titanium base alloy consumption factor at conversion ingot- conversion tube-bottle blank.

EFFECT: lowered labor consumption of conversion of ingot-blank of titanium base alloys conversion tube -bottle blank, improved efficiency of tube rolling plant, reduced cost of conversion tubes and commercial bottle blanks.

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