There are many shapes of rolling bearing ring raceway, as shown in Figure 1 below. There are three grinding methods for rolling bearing ring raceway: swing method, cut in method and generation method. These three methods have their own characteristics and application scope.
1. Swing grinding method: the principle of swing (also known as swing head) grinding is shown in Figure 2. This method is often used in groove grinding of ball bearings. During grinding, the workpiece rotates to form a wire on its surface, and the workpiece swings back and forth around the swing center at an angle a to form its surface bus. The grinding wheel rotates at a certain grinding speed and also makes radial feed motion.
The circular arc swing of the workpiece relative to the grinding wheel always keeps the fixed shape of the grinding wheel surface. In addition, the rubber bonded grinding wheel with good self sharpening is used. Therefore, it is not necessary to adjust the grinding wheel in the work.
In swing grinding, because the grinding wheel tracks do not coincide and the grinding wheel is worn evenly, good channel shape and roughness can be obtained. However, it is difficult to realize the absolute coincidence of the grinding wheel working surface center, groove curvature center and swing center in the work, and the vibration of the swing mechanism during reversing sometimes causes vibration marks on the machined surface. In addition, the time change of the grinding contact surface will also make the elastic deformation of the process system fluctuate periodically, thus affecting the machining quality.
2. Cut in grinding method. Cut in grinding is an advanced finishing method of bearing ring raceway, which is suitable for Raceway of any shape. The working principle is shown in Figure 3.
This grinding method is to trim the working surface of the grinding wheel into the shape of the raceway, and grind the raceway on the ferrule according to the principle of forming grinding. In grinding, the wear of the grinding wheel surface is uniform, and the self sharpening of the grinding wheel can not be brought into full play. Usually, the grinding wheel should be trimmed after grinding several workpieces. The advantages of cutting in method are simple machine structure, few adjustment links, good machining stability, easy to realize high-speed grinding and automation, etc. However, because the grinding track of sand particles is always in one position, the surface roughness is increased and easy to burn. At the same time, it is required that the rigidity of the machine tool is good, the quality of the grinding wheel is uniform, and the machining error of the previous process is small.
3. Fan Cheng attrition method. Figure 4 is the working principle diagram of generation grinding method, which is an advanced spherical raceway finishing method.
When the feed axis of the grinding wheel is perpendicular to the rotation axis of the grinding wheel, it is the working phase of the grinding wheel.
The outer diameter of the grinding wheel is slightly larger than the width of the workpiece. This kind of grinding method is special. It is grinded by the slope edge of the end face of the bowl grinding wheel, and there are usually two grinding arc lines on the workpiece surface. These two arcs are formed by the edge of the grinding wheel. They rotate around the axis of the workpiece to form a spherical raceway with network surface morphology, as shown in Fig. 5.
Therefore. This method can obtain good roughness.
Due to the use of grinding wheel edge grinding, this grinding method does not need a special dresser, but only rely on workers to manually repair the end face slope. If the special dresser is used, the labor intensity can be reduced, the production environment can be improved, and the regular grinding wheel surface can be obtained.
The above three grinding methods of raceway are applied to different degrees in the field of bearing production at home and abroad. Swing method is a relatively old process, which was used in earlier bearing factories. Most of the bearing plants that put into operation later use the cut in method. The generic method is used for medium and large spherical raceways.
