METHOD FOR PROCESSING PRECISION FORGING OF BEARING RING

Abstract

A near-net shape forming method for fabricating the precise bearing ring forging is invented. The processing method is composed of following three procedures. (1) the precise ring-like billet with chamfer angle is manufactured by the machining method. (2) The billet is heated by the less oxidation or non-oxidation heating method before ring rolling. (3) The bearing ring forging integrating with the raceway is formed in one pass of the rolling process by the ring rolling method.

Claims

1. A processing method for fabricating the near-net shape bearing ring forging, the processing method is comprised of following procedures. (1) The ring-like billet with chamfer angle is manufactured by the machining method. (2) The billet is heated by the less oxidation or non-oxidation heating method before rolling. (3) The bearing ring forging integrating with the raceway is formed within a single pass of the rolling process by ring rolling method.

2. The processing method according to claim 1, wherein said the machining method can be turning, drilling, milling or wire-electrode cutting method, or any combination of the machining methods.

3. The processing method according to claims 1 and 2, wherein said the ring-like billet with chamfer angle is a specially designed billet whose shape is like a ring, where a cylindrical hole is machined at the center of billet. Especially, the two inner edges and two outer edges of the ring-like billet are chamfered into round or oblique angles. Supposing that the said ring-like billet's width and height are represented by B and H respectively, the smaller value between the B and H is A=min(B, H). If the chamfer angle is round, the radius of the said round chamfer ranges from 0.1A to 0.5A. If the chamfer angle is oblique, the length of one side of the said oblique angle ranges from 0.1B to 0.5B, the length of the other side ranges from 0.1H to 0.5H.

4. The processing method according to claim 1, wherein said the less oxidation or non-oxidation heating method includes protective atmosphere heating, protective coating heating, vacuum heating, fast electro-magnetic induction heating.

5. The processing method according to claim 1, wherein said the bearing ring forging integrating with the raceway is formed in a single pass of the rolling process by the ring rolling machine.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1 a flowchart showing the invented compact near-net shape forming method of the bearing ring forging

[0027] FIG. 2 is a schematic cross sectional view showing the parameters of the ring-like billet with chamfered round angle

[0028] FIG. 3 is a schematic cross sectional view showing the parameters of the ring-like billet with chamfered oblique angle

DESCRIPTION OF EMBODIMENTS

[0029] Hereinafter, the embodiment of the present invention will be described with the reference to figures.

[0030] The invented compact near-net shape forming method of bearing ring forging includes machining the billet with chamfer angle, as FIG. 2 and FIG. 3 shown, heating the billet with less oxidation or non-oxidation method and ring rolling integrally with raceway together by the ring rolling machine.

[0031] Further, the machining method of manufacturing the billet with chamfer angle can be drilling, turning, milling or wire-electrode cutting method, or any combination of the above machining methods. The computer numerical control(CNC) machining center is recommended for manufacturing the ring-like billet with chamfer angle in order to obtain the high precision billet. This simple machining procedure can substitute the procedures upsetting.fwdarw.punching blind-hole.fwdarw.punching through-hole in the traditional forming method of ring forging. Hence, the processing line is greatly shortened. More importantly, dimensional consistency of the different billet can be ensured. The defects of the hole off-center, corner fracture and shrinking in traditional punching procedure are circumvented. High precision and high quality ring-like billet with chamfer angle is machined, which greatly improve the rate of finished products.

[0032] In the method of fabricating near-net shape bearing ring forging, referring to FIG. 2 and FIG. 3, the ring-like billet with chamfer angle is a specially designed billet whose shape is like a ring, where a cylindrical hole is machined in the center of billet. Especially, the two inner edges and the other two outer edges of the billet are chamfered into round or oblique angles, as FIG. 2 and FIG. 3 shown. Supposing that the ring-like billet's width is B and height is H, and the smaller value between the B and H is A=min(B, H), radius of the said chamfered round angle ranges from 0.1A to 0.5A. If the chamfered angle is oblique angle, the length of one side of the said oblique angle L.sub.1 ranges from 0.1B to 0.5B, and the length of the other side L.sub.2 ranges from 0.1H to 0.5H. Adopting the above specially designed ring-like billet, the contact area between the billet and the roller are sharply decreased. Therefore, the mold filling resistance are greatly reduced. More importantly, burrs and fishtail-like defects are circumvented because the chamfered angle forms into corner gradually in the rolling process.

[0033] In the method of fabricating near-net shape bearing ring forging, the ring-like billet is heated by less oxidation or non-oxidation heating method before rolling. The less oxidation or non-oxidation method can be fast electromagnetic induction heating method, protective atmosphere heating method, protective coating heating method or vacuum heating method. Further, the protective atmosphere can be the insert gases, such as Nitrogen and Argon, or mixed gases of the insert gases and the oxygen-exhausted ones, such as H.sub.2, CO, methane (CH.sub.4), ethane (C.sub.2H.sub.6) or propane (C.sub.3H.sub.8). For the protective coating heating method, the protective layer, such as glass powder or ceramics one, is painted on the surface of the ring-like billet firstly, then the billets are heated to the rolling temperature by heating furnace. For the vacuum heating method, the air is pumped out from the furnace chamfer before heating in order to completely prevent the billets from oxidation. The fast electromagnetic induction heating method is mainly used in the situation that the billet's outer radius is less than 150 mm. Because the less oxidation or non-oxidation heating method is adopted, the loss of the mass and the decarburized layer is very small, and the precise forming can be realized.

[0034] In the method of fabricating near-net shape bearing ring forging, the ring rolling process is performed on the ring rolling machine. The ring rolling machine can be vertical or horizontal ring rolling machine. In order to control the precision, the computer numerical control(CNC) ring rolling machine is recommended. The raceway is integrally formed in the rolling process even for the high temperature alloys.

EXAMPLE

Example 1

[0035] A bearing inner ring forging is fabricated. The material is high temperature bearing steel ANSI M50. A ring-like billet, with outer radius 108.5 mm, height H=42.8 mm and width B=30.8 mm, is designed and then machined with the CNC machining center. Radius of the chamfered round angle is designed as 13 mm. The billets are heated to 1120 C. by Nitrogen protective heating method. Then the D51-300 type ring rolling machine is used for fabricating the inner ring forging. The bearing ring forging is precisely formed integrally with the raceway within one pass rolling process. The machining allowance of produced bearing ring forging is only 1.5 mm, however, it is 4.0 mm with the traditional processing method.

Example 2

[0036] A bearing inner ring forging is fabricated. The material is high temperature bearing steel ANSI M50. A ring-like billet, with outer radius 108.5 mm, height H=42.8 mm and width B=30.8 mm, is designed and then machined with the CNC machining center. One radius of the chamfered round angle is 10 mm, the other radius of the chamfered round angle is 15 mm. The billets are heated to 1120 C. by vacuum heating method. Then the D51-300 type ring rolling machine is used for fabricating the inner ring forging. The bearing ring forging is precisely formed integrally with the raceway within one pass rolling process. The machining allowance is only 1.2 mm, however, it is 4.0 mm in the traditional processing method.

Example 3

[0037] A bearing outer ring forging is fabricated. The material is high temperature bearing steel ANSI M50. The ring-like billet, with outer radius of 122.2 mm, height H=43 mm and width B=34.5 mm, is designed and then machined with the CNC machining center. Radius of the chamfered round angle is 14 mm. The billets are heated to 1120 C. by protective gas heating method where the nitrogen mixed with H.sub.2 gases are used. Then the D51-350 type ring rolling machine is used for fabricating the outer ring forging. The bearing ring forging is precisely formed integrally with the raceway within one pass rolling process. The machining allowance is only 1.5 mm, however, it is 4.5 mm in the traditional processing method.

[0038] The embodiments and examples disclosed herein are illustrative and non-restrictive in any respect. The scope of the present invention is defined by the terms of the claims, rather than the embodiments described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

INDUSTRIAL APPLICABILITY

[0039] The method of fabricating bearing ring forging in the present invention can be applied to manufacture the anti-fatigue, long life bearing ring, especially for the high temperature steel or low elongation one. The processing line is greatly shortened and the processing cost is sharply decreased.