Miniature bearing level of accuracy and speed

。 Two basic concepts in centerless grinding through type, requirements artifacts have vitamin k Vj movement speed and rotational speed. Although the two speed is given from the form, type (see 9 - 162). And that they are associated with wheel speed. But actually, the movement of the workpiece depends mainly on its stress state. As shown in figure 9 - 43, under normal circumstances, when the workpiece loading device has just entered the area 1, the same as a sudden change in the stress state ( The movement research did not consider the phenomenon, only think Ⅱ workpiece in the grinding area. On the workpiece in the grinding い area eye movement characteristics, subject to further study) Acceleration, the labor is to produce mobile dv/DHR and rotation velocity v with grinding, workpiece movement to Ⅱ grinding area, its C 1 move velocity and rotation velocity basically stable. Figure 9 - if some process parameter 43 grinding area several improper selection and combination of words, may appear the following situations. First is artifacts can't active into grinding area 1, or although can barely into grinding area 1, 19 mobile very arduous, but its serious occurs between artifacts from each other. And the third is the workpiece rotation, play phenomenon occurred work-piece had occurred when heavy letter fly out of the grinding area. These two cases available motion parameters and ∑ ∑ y M, described, and thus leads to two basic 1) If mobile stability ∑ 0 or higher, y showed that the workpiece enough driving force to overcome resistance, workpiece moving forward smoothly, this situation is called stable workpiece moving. If the ∑ y < 0, the driving force to overcome resistance show that the workpiece, workpiece moving hard, said the situation for the workpiece moving instability ( Or unstable) 。 2) If the rotational stability of ∑ M,> M0 ( M。 For the value of the comprehensive effect of various factors, M out here. A value near zero, E and body size determined by experiment. ) The driving torque is greater than the impedance torque, the workpiece.> 0, the workpiece speed rotation ( At this point, the wheel brake function failure) , said the situation for the workpiece rotational instability. If M < M. , the driving moment of the workpiece is greater than the resistance moment, 8 v < 0, the workpiece rotation is very difficult. This situation is called rotational instability. If M = M0, ev is approximately equal to zero, the workpiece, the rotation velocity of keep constant average rotational workpiece. This situation is called workpiece rotational stability. 19, the derivation of the two concepts, help to deep research the motion law of centerless grinding and reveal its mechanical essence. To deepen the two concepts, some important technological parameters on the influence law of ∑ ∑ M and Y show in figure 9-20 4 and 9 - 45. In the two figure, the assumption is that the workpiece is the thin wall ring width of 10 mm, believing it is = = month month