9.螺栓1.ppt

基本拧紧技术 拧紧技术 为什么使用螺栓连接 扭矩－夹紧力 The 50-40-10 规则 夹紧力与摩擦力的关系 弹性松弛会影响夹紧力 软连接、硬连接 软、硬连接 结论： 扭矩 OK, 角度过低 扭矩 角度 扭矩 = OK 角度 = 过低 扭矩 = OK 角度 = OK 扭矩 OK, 角度过高 扭矩 = OK 角度 = 过高 扭矩 = OK 角度 = 过低 扭矩 = OK 角度 = OK 扭矩 角度 Clamp force Friction in threads Friction under nut or head 螺栓装配质量对产品的最终质量有着直接影响 为了得到质量合格的拧紧连接– 拧紧扭矩必须精确 连接件质量必须得到监控 from large heavy steel constructions to tiny brittle plastic parts Why fasteners? Fasteners are used to join two or more pieces together. There are two MAIN types of fasteners: threaded fasteners rivets Threaded fasteners have features that make them the best choice for many applications: Easy and quick assembly Facilitates frequent packaging changes of a basic product Allow different products to be assembled on one line Give access to parts that require service/maintenance Allow replacing of parts with short life Can be used to produce HIGH QUALITY joints Safety Critical: When the failure of this bolt position is highly likely to lead to safety failure and/or to the destruction of the entire vehicle and thus direct or indirect danger to life and limb. Quality Critical: When the failure of the bolt position will lead to malfunction of the vehicle. Customer Critical: When the failure of the bolt position would provoke annoyance among customers Explain Safety, quality and customer critical, Tightenings are made for large heavy steel constructions as well as for tiny brittle plastic part Atlas Copco knows how to manage this! Screw joints are split into two main groups related to how external forces are applied to them: Shear load/ tensile load The shear load is applied across the screw stem trying to cut it in two. The screw force acts through the friction between the surfaces to hold the parts together. The force and friction must be big enough to prevent the parts from slipping and from having the shear load act directly on the stem of the screw. Joints of this type are mainly found in the steel frames and similar structures. But there