Thermal Expansion Method of Bearing Steel Tapered Ring Rolling

Abstract

The invention discloses a thermal bulge forming method of a tapered bearing steel ring rolling part. The method comprises the steps of sleeving the outer circumference of a preheated bulge forming block in a bulge forming machine with the hot-rolled tapered ring rolling part; moving a preheated pressing block to fit the bulge forming block, and pressing the pressing block on the upper end surfaceof the ring rolling part; starting the bulge forming machine; radially extruding the ring rolling part through the bulge forming block from the inner taper surface of the ring rolling part, and synchronously axially the ring rolling part by the pressing block until the ring rolling part is subjected to plastic deformation, including increasing of the inside diameter and the outside diameter of thering rolling part, decreasing of the wall thickness and decreasing of the height; finishing the bulge forming after preset size is reached and the pressure is maintained; rotating the ring rolling part by 30 degrees around a center axis; flattening protruded marks which are formed on the inner taper surface of the ring rolling part in the bulge forming process by bulging throug the abovementionedoperation; and then sizing, wherein in the bulge forming process, the bulge forming temperature is 830-910 DEG C; the bulge forming speed is 0.61-1.61mm / s; the downward pressing speed is 0.21-1.21mm / s; and the pressure is maintained for 41-81s. The ring rolling part subjected to bulge forming is high in size accuracy and is mainly applicable to the fields such as the field of bearings.

Description

Technical field [0001] The invention relates to a bulging method of a ring piece, in particular to a thermal bulging method of a bearing steel tapered ring rolling piece. Background technique [0002] Bearing steel tapered ring-rolled parts are special-shaped ring-rolled parts with a tapered longitudinal section, which are mainly used in bearings and other industries. Due to the difference in diameter and size between the upper and lower ends of the tapered ring-rolled piece, the difficulty of bulging is increased, and the bulging process is not well controlled and easy to produce defects. [0003] The prior art discloses a method (CN102500708A) for thermally expanding a rectangular ring rolling piece of bearing steel to form a special-shaped ring. The technical solution is: the heated rectangular ring rolling piece of bearing steel is inserted into the bulging machine to make it The inner ring surface is sleeved on the periphery of the outer circumferential surface of the preheat...

AI Technical Summary

Problems solved by technology

[0004] When the above method is used to bulge the tapered ring rolling piece of bearing steel, due to the difference in diameter between the upper and lower end surfaces of the tapered ring rolling piece, most of the strain during bulging is concentrated on the small end surface of the tapered ring rolling piece, and the bulging After the forming is completed, a slope will appear on the large end surface of the tapered ring rolling piece from the inner diameter to the outer diameter direction, and the middle position of the inner wall of the tapered ring rolling piece will appear concave. If the bulging force is too large, the tapered ring will easily The rolled piece bulges upwards to form a bulging block

That is to say, after the bulging of the tapered ring rolling piece, there will be problems such as warping deformation, inner wall depression, and low dimensional accuracy.

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