The deformation of the inner hole in elliptical internal grinding can be divided into two types, one is that after grinding, the work piece has not been removed from the grinder, the other is the deformation of the work piece after being removed from the grinder. The former is due to the excessive clearance of the spindle bearing of the grinder, the poor combination of the bearing and the spindle surface, and the fact that the rotation center of the two gears of the bearing is not on the same axis. In addition, it is also necessary to consider whether the clamping of the work piece is reasonable (for the irregular shape of the work piece processed by the disk, attention should be paid to its balance). This kind of deformation is generally symmetrical deformation.
The second kind of deformation is mainly the elastic deformation caused by the clamping of the work piece . The work piece is clamped by a three-claw self-centering chuck of internal grinder, and the work piece has changed due to the clamping force. When the chuck is finished, the three claws of the chuck are relaxed and the work piece is reset. In order to avoid this deformation in inner hole grinding, the method of strengthening the wall thickness of the work piece can be adopted to improve the rigidity, that is, in the clamping part of the outer circle of the work piece, an elastic opening gasket (Fig. 5-51) is set, so that the chuck three claws clamp the gasket and finally fasten the work piece by the gasket. In this way, the three-point clamping force can be scattered on the circumference of the work piece, which does not cause the uneven force of the work piece and cause elastic deformation.