第六讲 螺纹.pptVIP

* Screw-sealed 密封管螺纹用于要求形成加压下不渗透的连接而又无需使用油脂或密封件的场合，有锥形和柱形。 Non-screw 用于生活管道连接，圆柱管螺纹 * * * * 螺纹制造精度影响螺纹的接触质量，需要规定其公差。5g6g表示中等精度。5是公差等级，g为偏差值。 * 第六讲 螺纹连接(Threads) 螺纹要素及分类 Key Elements and types 内外螺纹画法 Representations of internal and external threads 螺纹联接 Threaded connection 螺纹紧固件 Threaded fasteners * 螺孔 Threaded hole * 6.1 螺纹的形成、结构和要素 Generation , structure and key elements of thread ⒈ 螺纹的形成Generation A ● 螺旋线 Helix 　　一个与轴线共面的平面图形（三角形、梯形等），绕圆柱面作螺旋运动，则得到一圆柱螺旋体 ——螺纹。A cylinder thread is a long narrow projection of uniform cross the section in the form of helix ont the surface of a cylinder 制在圆柱体外表面上的螺纹叫外螺纹。External thread is a thread on the outside of a cylindrical surface ,as on a shaft. 制在圆柱体内表面上的螺纹叫内螺纹。Internal thread is a thread on the inside of a cylindrical surface, as in a hole. * 车外螺纹 Lathe external thread 车内螺纹 Lathe internal thread 工件 A Shaft 卡盘 Fixture 车刀Cutter 工件旋转 The part rotates 车刀沿轴向移动 The cutter move along the axis 2. 螺纹加工 Machining screw thread * ⒊ 螺纹的要素Key Elements of threads ⑴ 螺纹的牙型 Form of thread 三角形 Metric 在通过螺纹轴线的剖面上，螺纹的轮廓形状。The cross section of thread cut by a plane containing the axis. 梯形 ACME 锯齿形 Buttress 常用的有：Most often used: 牙型 Form * ⑵ 螺纹的大径和小径 Major diameter and minor diameter 大径：与外螺纹牙顶或内螺纹牙底相切的假想圆柱面的直径。D、d Major diameter: The largest diameter of a screw thread 小径：与外螺纹牙底或内螺纹牙顶相切的假想圆柱面的直径。 D1、d1 Minor diameter: The smallest diameter of a screw thread 牙顶 Crest 牙顶Crest 牙底Root 牙底Root 小径 大径 * 外螺纹 External thread 内螺纹Internal thread 牙顶Crest 牙底Root 牙底Root 牙顶Crest 大径Major Dia. D、d 小径 Minor dia. D1、d1 中径Pitch dia. D2、d2 螺纹的中径Pitch diameter： 一个假想圆柱的直径。该圆柱的母线通过牙型上沟槽和凸起宽度相等的地方。The diameter of an imaginary cylinder where the thread width is equal to space between the threads. * ⑶ 螺纹的线数Number of threads 沿一条螺旋线形成的螺纹叫做单线螺纹；Single thread: with only one start. 沿两条或两条以上在轴向等距分布的螺旋线所形成的螺纹叫做多线螺纹。Multiple thread: with two or more starts 单线螺纹 Single thread 双线螺纹 Multiple thread 瓶口三线螺纹 Tri