tailieunhanh - Machinery Components Maintenance And Repair Episode 1 Part 12

Tham khảo tài liệu 'machinery components maintenance and repair episode 1 part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Balancing of Machinery Components 265 Figure 6-4. Couple unbalance. Figure 6-4A. Discs of Figure 6-3C realigned to cancel static unbalance now have couple unbalance. Figure 6-4B. Couple unbalance in outboard rotor component. 266 Machinery Component Maintenance and Repair couple does not matter as long as its value is equal in magnitude but opposite in direction to the unbalance couple. Quasi-Static Unbalance Quasi-static unbalance Figure 6-5 is that condition of unbalance for which the central principal axis of inertia intersects the shaft axis at a point other than the center of gravity. It represents the specific combination of static and couple unbalance where the angular position of one couple component coincides with the angular position of the static unbalance. This is a special case of dynamic unbalance. Dynamic Unbalance Dynamic unbalance Figure 6-6 is that condition in which the central principal axis of inertia is neither parallel to nor intersects the shaft axis. Figure 6-5. Quasi-static unbalance. Figure 6-5A. Couple plus static unbalance results in quasi-static unbalance provided one couple mass has the same angular position as the static mass. Balancing of Machinery Components 267 Quasi-Static Unbalance Figure 6-5B. Unbalance in coupling causes quasi-static unbalance in rotor assembly. Figure 6-6. Dynamic unbalance. It is the most frequently occurring type of unbalance and can only be corrected as is the case with couple unbalance by mass correction in at least two planes perpendicular to the shaft axis. Another example of dynamic unbalance is shown in Figure 6-6A. Motions of Unbalanced Rotors In Figure 6-7 a rotor is shown spinning freely in space. This corresponds to spinning above resonance in soft bearings. In Figure 6-7A only static unbalance is present and the center line of the shaft sweeps out a cylindrical surface. Figure 6-7B illustrates the motion when only couple unbalance is present. In this case the centerline of the rotor shaft sweeps .