砖夹-砖块系统的传力机制及夹砖数量研究

Study on the Force Transfer Mechanism of the Fixture-brick System and the Number of Clamped Bricks

为了弄清砖夹-砖块夹持系统内部的传力机制及确定砖夹所能夹起的砖块数量,应用静力学平衡理论研究了受夹砖块在接触面上正压力和静滑动摩擦力的变化规律,获得了砖块在相互接触面上作用力的等效作用位置,并基于系统的极限平衡条件导出了砖夹所能夹起砖块的数量.结果表明,各砖块在接触面上的正压力相同但等效作用点不同,而静滑动摩擦力大小、方向和等效作用点都是变化的;受夹砖块系统的砖块在接触面上的静滑动摩擦力呈现两边高中间低的分布规律;正压力和静滑动摩擦力在各砖块接触面上的等效作用点则呈现出两边低中间高的分布规律;砖夹能夹起砖块的数量不仅与砖块的宽度、砖块与夹具间静滑动摩擦系数及砖块受夹的位置有关,还与工人手臂的提拉力和手掌的抓握力有关.

In order to clarify the internal force transmission mechanism of the fixture-brick clamping system and determine the number of bricks that can be clamped by the brick clamp,the variation rules of the positive pressure and static sliding friction force of the clamped brick on the contact surface are studied by using the static equilibrium theory,and the equivalent action position of the brick on the contact surface is obtained,and the number of bricks that can be clamped by the fixture is derived based on the limit equilibrium condition. The results show that the positive pressure of each brick on the contact surface is the same but the equivalent action point is different,and the static sliding friction force and the equivalent action point of each brick on the contact surface are variable;The static sliding friction force on the contact surface of the brick in the clamping system tends to be high on both sides and low in the middle;The equivalent action points of the positive pressure and friction force on the contact surface of each brick show a trend of low on both sides and high in the middle;The number of bricks that can be picked up by the fixture is not only related to the width of the brick,the friction coefficient between the brick and the fixture,and the position of the brick being clamped,but also related to the lifting force of the worker’s arm and the gripping force of the worker’s hand.