Wind power positioning bearing structure, characteristics and the limit analysis

Figure 1 1, wind locating bearing design for wind power typical position bearing design, using positioning bearing of the bearing arrangement, locating bearing should be fixed in the axes of the right end, bearing radial load and thrust load from gear, and NU type CRB bearing on the other side as a floating end bearing. Positioning bearing is a kind of high performance, two-way bearing, it replaced the CRB bearing and FPCBB bearing combination. It is yet another solution to replace some adopted in the design of cross positioning of the single bearing arrangement or double row 2 ts - DMTRB bearing arrangement. This based on the single row circular cone roller bearings, bearing at the outer ring attached a baffle ring. Figure 1 a typical locating bearing design 2 shows how positioning bearing bearing with two-way thrust load. Expressed as a coarse arrow lines is the main thrust of load spectrum of more than 99% of the time positive torque condition from the axial force produced by helical gear. During the state of positive torque, the load bearing are implemented through the bearing raceway, taper roller bearings and special structure can make the roller pure roll motion, well under complex load, and roller does not produce any ball bearing can produce tiny slip. High voltage power grid or generator of temporary failure, however, and during the braking of the implementation process of resonance, force and gear drive torque reverse axial force in a short period of time. In addition, there are other conditions, such as: when the generator is used as a motor, for ease of maintenance and in low-speed driving turbine rotor; And under the critical speed of a low-speed wind. All these conditions need to be bearing positioning in CiYaoFang upward, with fine arrow line ( See figure 3) Representation of the axial load. The secondary axial load by the large and small end of the roller to inner ring guard, outer ring baffle ring. Figure 2 2 load distribution and the orientation of wind power bearing structure of the standard of bearing cage is on the center line of the form, the cage will roller limit circle. Locating bearing, on the other hand, also can use the center line of cage, the cage will be limited to roller outer ring. This configuration can be equipped with two independent baffle ring, as shown in figure 3. What kind of structure is more suitable, depends largely on the gearbox gear process, and when heavy intermediate shaft is vertical load cabinet in place, this kind of structure is especially useful. Figure 3 with two removable rim baffle ring high-speed shaft often encounter of maintenance in use, and it also frequently. During the period of maintenance, output shaft components and complete the attached positioning bearing can slip out of the box body, similar to today's daily maintenance. 3, wind locating bearing the characteristics of wind power bearing the main features and benefits of the positioning: reduces the axial space. Single bearing to replace the conventional double row bearing arrangement, and reduced the design space, therefore, also reduces the heavy gear box the length and weight of the box body requirements, match the current design. Work at 360 ° load zone of the bearing with the positioning of the features, and thus improve the gear contact position. Reduce the cost of system. Reduce stress, improve the service life of bearing. During the positive torque during normal operation, the bearing in the 360 ° running load area, all the roller and raceway contact force as shown in figure 4. Figure 4 360 ° load zone according to the gear system caused by the radial load ( Fr) And the axial load, Fa） Ratio of the two relations, can the raceway/roller contact point of optimization. When the bearing design to do induced axial force produced by locating bearing is less than the gear thrust. As a result of the bearing reaction force and the gear axial ratio in load cycle remains the same, therefore, always enough to locate tapered roller gear axial force, as shown in figure 5. On either side of the outer ring at the same time can provide smaller flange, to prevent the possibility of reverse assembly during assembly, as shown in figure 6. Figure 5 positioning the load bearing area figure 6 with positioning of the flange bearing bearing clearance is precisely set during manufacturing, therefore, in the assembly, the need for manual regulation of the bearing clearance. Practical application, it must be precise control of bearing or bearing radial clearance range of the axial clearance, to ensure that in all of the operating load and temperature conditions, within the scope of the keep proper running clearance. Due to the fixed end is locating bearing and floating the NU type CRB bearing used in combination, therefore, does not need to maintain proper running clearance and manual adjustment. Typical analysis shows that for both support radial load and bearing axial load, load area is 360 ° the positioning of the bearing, the contact stress is less than 1300 MPa, And only carry axial load FPCBB bearing the same) , but only to bear radial load, but smaller load the CRB bearing stress is much smaller, as shown in figure 7. Figure 7 4 the comparison of contact stress, wind locating bearing limit of wind power gear box usually occurs early damage of the bearing and gear and fatigue, the damage and fatigue phenomenon due to the impurities shot indentation on the contact surface of the key. Due to the rotation of the output shaft suffer more impact, the shaft bearing and even more susceptible to damage due to the influence of impurities. Therefore, in order to improve the reliability of the output shaft, bearing positioning can be equipped with an impurity bearing material, and the roller surface coated with ES300 coating, maximize its reliability. Figure 8 shows a group, with statistical significance test results, DangTu covered by ES300 coating, 4 bearing life can be. 5 times. Figure 8 fatigue life test results: ES300 technology