真空度随真空管道长度变化规律研究

摘要

通过对PCB钻孔机抽真空设计的研究，借鉴流体力学理论中管道流体与管道摩擦模型，提出了真空度管道摩擦损失假设和管道真空负压损失摩擦系数，并推算出了实验管道的真空负压损失摩擦系数和真空负压随各种不同管径管道每米长度损失的计算公式，为PCB业界设计钻孔工序抽真空系统提供了具有实用价值的理论指导。%With the study on PCB drilling shop vacuum pressure lose data for deferent diameter vacuum tunnels, and with reference to the model of lfuids in tunnels rubbing with the wall of tunnels in the hydromechanical theory, the author set up a hypothesis of a vacuum-rate decease due to the air lfow friction on the wall of tunnels, proposed vacuum-rate decease frication constant, and calculated out the practical vacuum tunnel’s vacuum-rate decease frication constant, built up a formula to predict the vacuum pressure lose for different diameter vacuum tunnels. The formula can be useful to help engineers to design a vacuum system.