第五章带传动讲解.ppt

§5 Belt drives 带传动 §5-1 General considerations 概述 §5-2 Belt drive theoretical basis 带传动理论基础 §5-3 V-Belt drive design 带传动设计（V带） §5-4 Tension device of the belt drive 张紧装置 Belt drive design example 带传动设计实例 §5-1 General considerations 一、特点和应用 1 、优点  2 、缺点 3、 Applications 2、 Flat-belt 平形带 3、多楔带 Multiple V belt drive 4、 toothed belt drive 同步齿形带 § 2-2 Belt drive theoretical basis带传动理论基础 一、Forces in belts 1、带传递的力 二、应力分析 Stresses in belts 4. The total stress The total stress in the belt is equal to the sum of the bending stress plus the tensile stress which contains the centrifugal stress . Maximum stress is at the point where the tight side of the belt runs onto the smaller driving pulley. 三、带的滑动现象Creep and slipping of the belt1.带的弹性滑动 Creep of the belt （固有的、不可避免的正常现象） As the belt runs over the driving pulley, the belt becomes shortened and creeps along the pulley. As the belt runs over the driven pulley, the belt is elongated and creeps along the pulley. 四、失效形式和计算准则Types of failure design criteria  1. 失效形式Types of failure ：打滑、带疲劳破坏 Slip fatigue failure ⑶不打滑且有一定的疲劳强度时，传递的功率P0：In order to prevent slipping and ensure necessary fatigue strength, transmitted power is limited as follows: △P0 ＝0.0001 △T×n1 （ △T：扭矩修正值 The torque correction factor） ⑵ K α ——包角系数 Contact angle factor （ α180° →P ↓ ） § 5-3 带传动设计（V带） V-Belt drive design Ld ↓→V/L ↑ (带单位时间 内绕过带轮的次数 Times running over a ↓ pulley in one unit of time ） →寿命 Service life↓ α1↓→Femax↓ 尺寸Overall size↑→ 工作时 拍击、颤动 Shocks and flapping occur in operation 2.长度 Length 3. 根数 Numbers § 5-4 张紧装置Tension device of the belt drive Pd↓ 、n1 ↑（高速轻载 High-speed and light-load） →选截面较小的V带 Select V-belts of smaller cross-section dimensions ： Y、Z、A型 由于带的弹性和拉力差 引起的带与带轮之间的