Rolling forming method for 5CrNiMo steel thin-wall ring

Abstract

The invention discloses a rolling forming method for a 5CrNiMo steel thin-wall ring, which is used for rolling and forming a thin-wall ring with high dimensional precision and good texture and properties. In the technical scheme of the method, a 5CrNiMo steel pre-rolled compact heated to a deformation temperature and a preheated following-up die sleeve are firstly sleeved into a ring rolling mill, the following-up die sleeve is sleeved into the pre-rolled compact, and the two workpieces are positioned through a main roller, a core roller, a holding roller, an upper cone roller and a lower cone roller of the ring rolling mill; the ring rolling mill is started again, the core roller of the ring rolling mill does a feed motion toward the direction of the main roller along a radial direction, and the core roller and the main roller roll the pre-rolled compact with rolling force of 180KN-3800KN under the support of the following-up die sleeve together so that the pre-rolled compact is broadened along the radial direction at the speed of 6mm / s-12mm / s, and the wall thickness of the pre-rolled compact is gradually decreased; and the pre-rolled compact is rolled into a thin-wall ring after the deformation reaches 30%-50%. The minimum of the wall thickness of the 5CrNiMo steel thin-wall ring rolled and formed by adopting the method is 25mm, and the maximum of the depth to thickness ratio is 25mm. The ring is mainly used for rotor parts used in the field of special vehicles, and the like.

Description

technical field [0001] The invention relates to a rolling forming method of a ring forging, in particular to a rolling forming method of a 5CrNiMo steel thin-walled ring. Background technique [0002] 5CrNiMo steel is a commonly used hot work die steel. The steel thin-walled ring formed by rolling process requires high strength, toughness and wear resistance. It can still maintain high hardness when heated to 500 ° C. It is mainly used for Rotary parts used in special vehicles and other fields. During rolling, due to the small deformation of the ring, the thinner wall thickness, and the higher requirements for dimensional accuracy, performance and structure, the difficulty of rolling and forming is increased. [0003] Chinese Invention Patent Specification CN 101279343A published on October 8, 2008 discloses a rolling forming method for stainless steel special-shaped ring forgings. In this method, alloy bars blanked according to specifications are subjected to upsetting, pu...

AI Technical Summary

Problems solved by technology

When using this method to roll thin-walled 5CrNiMo steel thin-walled rings, since the rolling die is fixed on the roll (that is, the main roll and the core roll), the gap between the pass of the rolling die and the pre-rolled billet will Intense friction not only makes the rolling process very unstable and affects production, but also easily leads to the temperature rise of the pre-rolled billet, which affects the structure and properties of the steel, such as defects such as structure variation and coarse grains.

[0004] When using the above method and directly using the main roll and core roll of the ring rolling machine to roll (such as the rolling ring billet in the above method) thin-walled 5CrNiMo steel thin-walled rings, due to the rigidity of the core roll and other components of the ring rolling machine In addition to the poor structural rigidity and small machining allowance of the thin-walled ring, it is easy to cause plastic instability of the pre-rolled billet during the rolling process, resulting in flattening, bell mouth, etc., resulting in the shape and size of the ring not reaching It is scrapped due to design use or machining requirements, which will cause certain losses to the 5CrNiMo steel that is not cheap

[0005] During the rolling process, when the pre-rolled slab is first rolled, the rolls are shifted to one side of its rotation direction, and then to the other side, so that the pre-rolled slab has a tendency to move toward its other side during the rolling process. The holding rollers on both sides swing left and right, affected by the reaction force generated by the holding rollers, the rings are easily crushed and scrapped

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