针对四点接触球轴承钢球与沟道间发生多点接触引起轴承过早失效的问题,以 QJ214 四点接触球轴承为研究对象,建立了钢球-沟道接触模型,分析了结构参数及工况参数变化时钢球-沟道发生多点接触的成因.研究结果表明,内外圈沟道曲率半径系数或内外垫片厚度的增大可使钢球-沟道接触状态由三点接触转变为两点接触,再转变为三点接触;恒定转速时,轴向载荷的减小可使钢球-沟道接触状态由两点接触转变为三点接触;转速及轴向载荷均恒定时,径向载荷的增大可使部分钢球-沟道接触状态由两点接触转变为三点接触,再转变为四点接触.研究成果为避免四点接触球轴承在运转过程中发生多点接触而引起的猫眼圈磨损失效提供了参考.
针对航发主轴轴承在高速轻载下存在的打滑问题,在构建某航发圆柱滚子轴承仿真模型的基础上,研究了滚子数、滚子长度、初始径向游隙、保持架引导间隙等结构参数对轴承打滑和疲劳寿命的影响规律.结果表明,增加滚子数和保持架引导间隙,减小滚子长度和初始径向游隙,可以有效降低轴承打滑率.采用正交设计方法,得到滚子数、滚子长度、初始径向游隙、保持架引导间隙对轴承打滑、轴承疲劳寿命、内滚道磨损率的影响权重.通过综合平衡优化,得到当滚子数、滚子长度、初始径向游隙、保持架引导间隙分别为13 mm、6 mm、-2μm、1 mm时,保持架打滑率为0.29％,内滚道磨损率为5.9×10-13 m3/s;在保证轴承寿命的同时,降低了轴承发生打滑蹭伤、磨损失效的概率.
There are 189 kinds grasses used by rabbits.In this study,twenty-four juvenil and young eight dot black rex rabbits the weight of which was 1750.4±369.9g,were used to study the palatability of twenty-eight kinds grass.Experimental rabbits were divided into four groups: A,B,C and D,every group had six rabbits.Four kinds grasses were study in every batch experiment for 4 days,one kind grass was used by every group.The diets for every rabbit was 50g grass the first day,100g grass the second day,150g grass the third and forth day.The results indicated that the palatability of thirteen kinds grass was good,occupying 46.4%,edible rate of which was more than 80%.The palatability of six kinds grass was very good,occupying 21.4%,edible rate of which was 70%-79%.The palatability of four kinds grass was middling,occupying 14.3%,edible rate of which was 60%-69%.The palatability of five kinds grass was very bad,occupying 17.9%,edible rate of which was 50%-59%.The best feeding grass of juvenil and young rabbit per day is 100g in this study and the palatability of grass used by rabbit was divided into five grades,good,very good,middling,very bad and bad,and the value of grass and the development of rabbit after feeding grass was know.The results can establish base for the study on palatability,nutritive value,value for drug and digestibility of other grasses,and provide science evidence for reasonable using grasses to feed rabbits.
