FABRICATION METHOD OF SEAMLESS HOT-DEFORMED TUBES OF LARGE AND MEAN DIAMETRES ON TUBE-FORMING INSTALLATIONS WITH PILGER MILLS Russian patent published in 2010 - IPC B21B21/00 

FIELD: metallurgy.

SUBSTANCE: method involves heating of ingots and workpieces to ductility temperature, their conversion to hollow thick-walled shells in skew rolling mill on a short mandrel, repeated heating of thick-walled shells to ductility temperature, rolling to thin-walled shells in skew rolling mill, rolling of shell to tubes on pilger mills in profiling rolls on a long holder - mandrel; at that, conversion of ingots and workpieces to thick-walled shells is performed in the first skew rolling mill, and rolling to thin-walled shells - in the second skew rolling mill installed parallel to the first one with an offset of outlet and inlet sides; total power of drives of piercing mills is determined from the following equation: (N₁+N₂)=(1.1-1.15)N_max, where N_max- maximum power of drives of skew rolling mill, which is required for conversion of maximum diametres of ingots of electroslag remelting process and workpieces for rolling the tubes with maximum diametre from difficult-to-form grades of steel and alloys for this tube-forming installation, kW; N₁ -power of drives of the first skew rolling mill for conversion of ingots and workpieces to thick-walled shells, kW; N₂ - power of drives of the second skew rolling mill for rolling thick-walled shells to thin-walled ones, kW, and power of drives of skew rolling mill for conversion of ingots and workpieces to thick-walled shells is determined from equation N₁=K(N₁+N₂), where K=(0.55-0.60) - coefficient for determining power of drives of skew rolling mill in order to convert ingots and workpieces to thick-walled shells.

EFFECT: increasing efficiency of tube-forming installation with pilger mills, decreasing coefficient of metal consumption, which provides the possibility of forming the stock of orders with tubes in small batches, and reducing production cost of tube products.

3 cl, 1 tbl