The Key Technology Research On Speed Improvement For The Grinding-Wheel Spindle Of Large Roll Grinder

The large roll grinder, which has been widely used in industries such as metallurgy, papermaking and shipbuilding, is important equipment for manufacturing of large-scale rollers. Its grinding precision and efficiency are mainly affected by the rotating accuracy and the speed of its grinding-wheel spindle. Moreover, core component of the grinding-wheel spindle bearing system, the front static and dynamic hydrodynamic lubrication radial sliding bearing is a key part to determine the speed and rotating accuracy of the spindle. This dissertation mainly focus on the front bearing of spindle, a core component of the grinding-wheel spindle bearing system of the large roller grinder MK84250 which was newly developed by Guiyang Xianfeng Machine Tool Co., Ltd.Aiming at the key factors which affect the working performance such as bearing capability, temperature rise, etc., calculation and verification were carried out. A simple calculating method was put forward, which is apt for the special structure bearing discussed in this dissertation. According to the experiments, the calculating method was verified to be applicable. On the basis of this, a new structure bearing was developed, and the feasibility and rationality of the bearing were verified by calculating and experiments. Main research contents in this dissertation include:-1、Solution procedure was investigated to analysis the static and dynamic hydrodynamic lubrication bearing used in MK84250. The structure of roller grinder and a typical three-oil-chamber structure of the liquid hybrid bearing were introduced. Then analyzed the force bearing status and the operating process of the hybrid bearing.2、The solution-domain for the hydrodynamic oil film of the bearing was studied, and result shows that the start-point coordinate of the solution-domain is determined by the angle of displacement. A new simple method was put forward to calculate the angle of displacement while solve the oil film pressure by quasi-two-dimensional method. The solution process for the liquid hybrid bearing was designed and analyzed. Moreover, details for the solving process and the critical points were introduced as well. According to the solution procedure, deduced the dimension normalization formula of the Reynolds equation. It was obtained that the non-dimensional and dimensional distribution of the oil film by employing Matlab toolbox’s numerical computation. The equation and curve for bearing capacity coefficient-eccentricity ratio（S₀-ε） were also obtained by fitting. On the basis of the equation and curve, this thesis calculated and verified the bearing capacity and temperature rise at the ultimate speeds of 45m/s and 60m/s. And the experimental results show that the calculation process and method are reliable and applicable.3、The calculation result shows that, to the roller grinder MK84250, front bearing for the spindle cannot work properly due to over-heat while the grinding linear speed of the grinding-wheel went up to 60m/s. Under this condition, a series of improved designs are needed to solve the problem of over-heat. According to the cost minimization and the analysis, the basis and directions for the further design were put forward. And the improved static oil chamber and bearing were designed to increase oil flow and enhance the heat dissipation. Radius diameter ratio B/D=0.7 biserial narrow-bearing was designed, and its bearing capability of the static oil chamber was verified as well. At the same time, on basis of such an improvement, the corresponding components for the bearing such as the eccentric sleeve, annular oil groove, etc. were also adaptively designed. And the capillary-throttler mounted in original static chamber was calculated and analyzed.4、The bearing capability and temperature rise for the new structure bearing were calculated and verified by employing the methods which was put forward in this dissertation. The results of investigation indicate that the bearing capability of the new structure bearing exceeds the initial MK84250 spindle bearing at the same-grinding-wheel linear speed of 45m/s. On the condition of 60m/s, the interior effective temperature of the new bearing can meet the requirement. Moreover, according to the primary-analysis, the new bearing can also normally running while the speed of grinding-wheel is increased up to 70m/s. The temperature rise, leaked oil mass and stiffness of the new structure bearing were detected by experiments, and the results obtained are close to the theoretical calculation. That verified the applicability of the new structure bearing.