Tham khảo tài liệu 'harris' shock and vibration handbook part 17', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CHAPTER FORTY FIGURE Deflection of machine-tool spindle and bearings. A machine-tool spindle can be regarded as a beam on flexible supports. The total deflection under the force P consists of the sum of A the deflection X1 of a flexible beam on rigid supports and B the deflection X2 of a rigid beam on flexible supports. H. FIGURE Deflection of a beam on elastic supports as a function of the bearing distance. Bearing stiffness kA and kB spindle stiffness ko After H. placing them near the main column etc. by using rigid tools and clamps by using jigs which rigidly clamp and if necessary support the workpiece by clamping securely all parts of the machine which do not move with respect to each other etc. and by the optimization of mounting conditions mentioned above. The static and dynamic behavior of machine tools is influenced significantly by the design of the spindle and its bearings. The static deflection of the spindle consists of two parts X1 and X2 as shown in Fig. . The deflection X1 corresponds to the deflection of a flexible beam on rigid supports and X2 corresponds to the deflection of a rigid beam on flexible supports which represent the flexibility of the bearings. The deflection of the spindle amounts to 50 to 70 percent of the total deflection and the bearings 30 to 50 percent of the total depending on the relation of spindle cross section to bearing stiffness and span. The stiffness of antifriction bearings depends on their design accuracy preload and the fit between the outer race and the housing responsible for 10 to 40 percent of the bearing deformation3 . The distance between the bearings has considerable influence on the effective stiffness of the spindle as shown in Fig. ordinate of the figure corresponds to the deflection in inches per pound and the abscissa represents the ratio of bearing distance b to cantilever length a. The straight line refers to the deflection of the spindle and the .
