METHOD OF PRODUCTION AND OPERATION OF PILGER MILL MANDRELS Russian patent published in 2008 - IPC B21B25/00 B23P6/00 

FIELD: pipe rolling.

SUBSTANCE: applicable for production and operation of pilger mill mandrels. Cakes are cast from the carboniferous-grade steel. The heat-resistant wear-proof coating is applied to the cakes by weld depositing. Mandrel semifinished items are produced from the cakes by pilger mill rolling followed by thermal treatment of the mandrel semifinished items. Then mechanical treatment is performed to achieve the finish size, followed by strengthening by wheel rolling. In the process of mandrel operation upon emerging of the crevice array, the mandrel regrinding is performed multiple times until full removal of the heat-resistant wear-proof coating; then the new heat-resistant wear-proof coating is applied by weld depositing, followed by mechanical treatment to achieve the finish size, and strengthening by wheel rolling. The heat-resistant wear-proof coating of constant thickness is applied at the bottom end of the cake while producing the mandrels, up to two-thirds of the cake's height. The thickness of the mentioned coating layer is gradually reduced by 2-3 times toward the pipe end of the cake. After the mandrel regrinding, the heat-resistant wear-proof coating is applied to two-thirds of their length from the mandrel head to the front conic part of the mandrel while gradually reducing the layer thickness by 2-3 times. The heat-resistant wear-proof coating layer thickness on the cakes Δ and on the mandrel semifinished items Δ₁ is defined from the given formulae.

EFFECT: mandrel durability and material saving.

2 cl, 1 tbl