Reasons affecting roundness of inner race groove of rolling bearing

The reasons affecting the roundness of the inner race of rolling bearing.
1. The roundness of the inner race of rolling bearing is an important quality index, which directly affects the working accuracy, stability and service life of the bearing. Grinding is usually a semi finishing or finishing process of the inner ring channel, which plays a decisive role in the roundness of the finished inner ring channel. In addition to the accuracy and dynamic characteristics of the grinding process system, the roundness of the inner ring channel grinding is also closely related to the grinding process parameters. The former has been valued by many scholars and a lot of research has been carried out, which greatly improves the roundness of grinding inner ring channel. With the improvement of grinding process system accuracy and dynamic characteristics, grinding process parameters have become the main factor affecting roundness. Therefore, the study of the influence law of grinding process parameters on roundness is of great significance to reasonably select process parameters, ensure the grinding roundness of bearing channel, and then realize the optimization of grinding process parameters of bearing channel.
2. The groove of bearing inner ring usually adopts variable feed rate cut in grinding, and its grinding cycle can be divided into four stages: workpiece fast approaching, coarse feed, fine feed and no feed grinding. The main factors affecting the roundness of grinding bearing channel can be summarized as follows: (1) the accuracy of the process system in the grinding process, which depends on the accuracy of the grinder and the positioning principle, structural parameters and accuracy of the fixture; (2) the dynamic characteristics of the process system, especially the balance state of the grinding wheel: in the process of dressing and grinding, the grinding wheel is unbalanced, which will cause forced vibration, Due to the difference between the relative position of the dresser and the grinding wheel when dressing the grinding wheel and the relative position of the workpiece and the grinding wheel during grinding, and the different stiffness of the process system under these two different conditions, the vibration causes the workpiece surface to be out of roundness. The grinding process parameters will affect the contact stiffness between the grinding wheel and the workpiece, the wear process of the grinding wheel and the damping characteristics of the vibration of the process system, The vibration characteristics of grinding process are affected by the geometrical shape (i.e. roundness) and other surface quality of grinding workpiece: (3) the original error reflection caused by elastic deformation of the process system: the change rule of geometrical error of grinding cycle workpiece can be known. The geometric error remapping of the workpiece after grinding mainly depends on the rigidity of the process system Grinding process parameters, grinding wheel wear speed and workpiece original error?. Considering the above factors, when the stiffness and dynamic characteristics of the process system are certain (especially the grinding wheel must be well balanced), the roundness error of the grinding workpiece mainly depends on the grinding process parameters. Therefore, through the stepwise regression modeling of the grinding roundness test data, select important parameters from multiple process parameters and gradually introduce the regression equation, The optimal regression equation between grinding roundness and process parameters is established.
3. Machine tool vibration caused by unbalanced grinding wheel or other factors will seriously affect the roundness of grinding workpiece. Keeping the good working state of the machine tool and the good balance of the grinding wheel is the prerequisite for the application of the above fitted roundness mathematical model. In addition, the hardness, structure, particle size and abrasive type of grinding wheel, as well as the composition of coolant, will have a certain impact on the roundness of grinding.