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Bearing steel performance and requirements

Date锛2013-09-06 9:26:18

Rolling bearing parts timber , including timber and cage , rivets and other supporting material. Bearings and parts thereof Most are made of steel , high carbon chromium bearing steel is usually steel and hardened steel . With the development of modern science and technology and the increasing use of rolling bearings , the bearings have become increasingly demanding , such as high precision, long life and high reliability . For some special purpose bearings , bearing materials also requires high temperature , corrosion-resistant , non-magnetic, ultra-low temperature , anti-radiation properties. In addition , bearing materials include alloys, non-ferrous metals and non-metallic materials. In addition, the ceramic material of the bearing has been used in motorcycle , car , subway , aviation, aerospace, chemical and other fields.
Rolling the basic requirements of the material depends largely on the bearing performance. Select Manufacturer bearing material is appropriate, its performance and life will be greatly affected. Under normal circumstances , bearing the main damage is in the form of alternating fatigue spalling under stress , as well as leaving the bearing friction and wear loss of accuracy . In addition , there are cracks , dents , rust and other causes of bearing non-normal damage. Therefore, the bearing should have a high resistance to plastic deformation , the less friction and wear , a good rotation accuracy , good dimensional accuracy and stability, and long contact fatigue life. And many of them are by the material properties and heat treatment process of joint decision . Rolling the material as the basic requirements are determined by the failure mode of the bearing , so the requirements of manufacturing of the material after rolling a certain heat treatment after the process should have the following properties:
a high contact fatigue strength
Bearing contact fatigue damage is the main form of normal damage . Rolling operation , rolling in the bearing inner and outer raceways between rolling , the contact part of the cycle of alternating load to bear , and more are up to several thousands of times per minute , alternating stress in the cycle repeated , the contact surface fatigue spalling . Rolling began to appear after peeling will cause bearing vibration, noise , temperature increased sharply , resulting in damage to the bearing end , the damage in the form known as contact fatigue damage. Therefore, the requirements should have high steel rolling contact fatigue strength .
b high wear resistance
Rolling normal working hours, in addition to rolling friction occurs , but also accompanied by sliding friction . The main part of sliding friction occurs are: rolling element and raceway contact surface between the rolling elements and cage pockets between the contact surfaces , and a ferrule holder between the guide wall and the roller end face of the ferrule guide between ribs and so on. Rolling in the presence of sliding friction of the bearing parts inevitably produces wear. If the poor wear resistance of bearing steel , roller bearing will wear prematurely due to loss of precision or accuracy decreases due to leaving the rotating bearing vibration increases, reduced life . Therefore, the required bearing steel should have high wear resistance .
c high elastic limit
Rolling operation, the rolling body and the contact area between ring raceway is small , bearing under load , especially when subjected to high loads in the case, the contact surface contact pressure. In order to prevent too high contact stress large plastic deformation occurs , the bearing loss of accuracy or the occurrence of surface cracks, therefore , required to be bearing steel having a high elastic limit .
d suitable hardness
Hardness is an important indicator of rolling bearings . It is in contact with the material fatigue strength , wear resistance, elastic limit is closely related to , directly affect the life of rolling bearings , bearing hardness is usually bear the load according to the manner and bearing size , bearing size and wall thickness of the overall circumstances. Rolling steel hardness should be appropriate, too large or too small will affect bearing life. As we all know , the main failure mode is rolling contact fatigue damage, as well as wear resistance, dimensional instability leaving poor or loss of precision bearings ; bearing parts if a certain lack of toughness to withstand greater impact loads will occur as a result of brittle fracture bearing damage. So, must be based on the specific circumstances and damage the bearing way to determine the hardness of the bearing . For errands wear due to fatigue spalling or loss of precision bearings circumstances bearing parts should be used in higher hardness ; withstand greater impact loads for bearings ( eg mill : bearings, railway bearings and some auto bearings ) , should be appropriately reduced hardness in order to improve the toughness of the bearing is necessary .
e certain toughness
Many Rolling in the course will be - given the impact load , thus requiring bearing steel has a certain toughness , in order to ensure the bearing is not due to impact damage. For withstand greater impact load bearing such as rolling bearings, railway bearings require a material with a relatively high impact toughness and fracture toughness, these bearings are some with bainite hardening heat treatment process , some with hardened steel materials, is to ensure that these bearings have good resistance to impact toughness.
f good dimensional stability
Rolling is a precision machine parts , its accuracy is micron dollars. In the long-term storage and use, due to internal organizational changes or stress can cause changes in the size of the bearing , resulting in the loss of precision bearings . Therefore, to ensure the dimensional accuracy of the bearing , bearing steel should have good dimensional stability.
g good rust resistance
Rolling many production processes , the production cycle is longer, some semi-finished or finished parts before assembly extended period of storage needed , therefore , the bearing parts in the manufacturing process or in the finished product must be stored in both prone to corrosion , particularly in humid air. Therefore , bearing steel required to have good anti-rust properties.
h good process performance
Rolling in the production process, its parts to go through multi-channel cold and hot processing operations. This requires bearing steel should have good process performance, such as cold and hot forming properties, cutting, grinding and heat treatment processing performance properties , etc., to accommodate rolling high-volume, high efficiency, low cost and high quality production.
In addition , for special operating conditions using the bearings , apart from these few basic requirements, it must also be made of steel corresponding special performance requirements, such as high temperature resistance , high-speed performance , corrosion resistance and magnetic properties.

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