钢球展开过程运动学及动力学分析

钢球表面质量检测常用的办法是依靠展开机构中的摩擦力将钢球表面完全展开，摩擦力对钢球表面检测效率和精度有着重要影响。为分析摩擦对钢球展开的影响，根据展开轮与钢球接触的几何约束关系，对钢球与展开轮接触模型进行运动学分析，得到钢球与展开轮接触点位置的变化规律；由于展开装置构件之间全部依靠干摩擦接触约束，在古典Coulomb摩擦模型基础上，结合展开装置特性，建立修正的Coulomb摩擦模型，建立钢球和展开轮的运动微分方程，得到钢球与展开轮接触点处摩擦力的变化规律，并分析接触点处接触力的影响因素；同时根据展开原理构建实体模型进行虚拟仿真并搭建物理样机进行试验，结果表明驱动轮转速直接影响钢球与展开轮接触点法向接触力变化，从而影响接触点处摩擦力变化特性，通过摩擦力变化特性，解释了展开轮能实现钢球表面展开的工作原理。

Dynamic Characteristics of Steel Ball Surface Unfolding Process

The method of steel ball surface quality detection is to rely on the mechanism friction to expand the ball surface completely. The friction has an important influence on the detection efficiency and effect. For the analysis of friction effect on steel ball expansion, according to the geometric constraint relationship between wheel and the steel ball contact, to carry out the motion and position analysis, then obtain the position variation of contact point between wheel and the steel ball; Because all components of expansion device depend on the dry friction constraint, based on the classical Coulomb friction model, establishes the modified Coulomb friction model in combination with device features, and establishes the movement differential equation between steel ball and unfolding wheel, obtains the change law of friction for contact points of steel ball and unfolding wheel, and analyzes the influence factors of contact force; At the same time, according to the unfolding principle, the entity model is built for virtual simulation, and the physical prototype is built for test. The results show that the driving wheel speed directly affect the normal contact force changes of contact point between steel ball and unfolding wheel, which affects change features in friction of contact point, the principle of steel ball surface unfolding by unfolding wheel can be explained through changing friction characteristics.