Atlas Copco基本拧紧技术 PPT课件

Tensile load
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AC tightening technique
Bolt tension = 20 kN
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Bolt tension = ?
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ton
Bolt tension = ?
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Different ways of assembling装配的不同方 法
• Welding(焊接) • Gluing(粘接) • Riveting(铆接) • Tightening with screws and bolts(螺
栓拧紧连接)
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• 我们需要的是连接件中的夹 紧力
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AC tightening technique
Torque measurement扭矩测量
Clamping force is the aim at but it is hard to measure. Torque is easy to measure and apply.夹紧力是目标但是比较难测量但是扭矩 比较容易测量
外部负载的变化只有很小的一部分会转移到螺栓上=>这样螺栓就不容 易由于负载的交变而产生疲劳损坏
It provides a frictional grip => It will not come apart if the parts cannot move in relation to each other
interface. 界面中没有夹
紧
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The Joint Loaded by an Applied Force
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Question
What is the major difference between a bolted joint on one hand and a welded, glued or riveted joint on the other hand?螺栓连接和焊 接铆接粘接有什么最大的区别
The applied torque is measured应用力矩
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Clamping force Needed需要的夹紧力
Torque T=Fxr
F
Ta
Tb
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r
F
Ta=Fr
Tb= ½ Fr
Result: Ta= 2 Tb
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Clamping force vs tensile load and shear load夹紧力和 螺栓张力和剪切力
Tensile load
Clamping force
Shear load
Shear load
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AC Tightening Technique
阿特拉斯·科普柯拧紧技术
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BASIC TIGHTENING TECHNIQUE
基本拧紧技术
基本拧紧技术
介绍装配过程中的基本问题，为正确和使用选择工具提供指导
对客户来讲，成功的关键是所使用的工具／设备能够匹配其特定需要．
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AC tightening technique
ton
= 10 kN
Is the bolt tension now approximately…….. 现在螺栓的拉伸力大约是多少?
10 kN?
20 kN?
Or 30 kN?
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AC tightening technique
The Correct answer is: 正确的答案是:
VDI 2230， 德国工程师协会 2230标准
基于从1960年代就开始的研 究，德国工程师协会(VDI， German Society of Engineers) 发布了VDI2230：高负荷连接 的系统计算方法 － Systematic Calculation of High Duty Joints.
螺栓伸长δ1
连接件 压缩δ2
变形
连接图解
轴向工作载荷的影响
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AC tightening technique
力
螺栓受力
增加部分
工
夹紧力
作 载
减少部分 荷
σδ1
δ1
δ2
变形
Joint Diagrams 连接图解
通过螺纹产生夹紧力把连接件夹紧
• 旋转螺母或螺丝使螺丝受力 伸长
• 螺丝伸长产生的夹紧力把连 接件夹紧
历史背景
十九世纪工业革命开始，为得到 更大的生产力要求工业产品必须 达到： •系统化 •质量可控性 •可复制性
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AC tightening technique
连接图
德国人Rotscher 在1927年提出了连接图，这种方法直到今天仍在使用，帮 助我们理解连接的力学特性和进行计算。
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INTERESTING – BUT WHAT IS THE VALUE OF THAT? 意义-但是这个价值是什么
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Variations in external loads are only to a small extent transferred to the bolt => The fatigue resistance of the bolt becomes very high
THE BOLTED JOINT IS PRELOADED!螺栓连接 有预加负载
And what is the consequence of this diffference?
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AC tightening technique
Question
What is the major difference between a bolted joint on one hand and a welded, glued or riveted joint on the other hand?
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AC tightening technique
施加的力不要超过使用极限
• 施加的力过大会使 螺栓过度伸长
• 安全余量取决于: – 拧紧精度 – 材料等级
N 夹紧力
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AC tightening technique
螺栓拉伸量
螺栓连接应用的历史背景
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½r
F = applied force (in Newton)
r = lever length (in meters)
为了拧紧螺栓, 必须施加力以便拧紧螺母/螺丝
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AC tightening technique
Clamping force depends on torque and other factors 夹紧 力的因素是扭矩和其余的因素
20 kN – the bolt pretension will NOT change (much)螺栓上承受的拉伸力 是不会变化的
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The Special Fastener 特殊模式
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The Use of the Special Fastener拧紧这个模式
• Standardised well-defined element(标准化)
• Cost-efficient(节省成本)
• The bolt should be weakest link(设计 成最薄弱环节)
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The thread creates the clamp load that holds the joint together螺纹建立夹紧载何使得 工件被夹紧)
THE BOLTED JOINT IS PRELOADED! And what is the consequence of this diffference? ONLY A SMALL PORTION OF THE EXTERNAL LOAD IS TRANSFERRED
TO THE BOLT!
And what is the consequence of this difference?这个不同点有什么重要的
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AC tightening technique
Question
What is the major difference between a bolted joint on one hand and a welded, glued or riveted joint on the other hand?
• Turning the nut or screw stretches the screw(旋转螺母或 者螺栓拉深螺栓)
Clamping force
• Stretching the screw clamps the parts together(拉伸螺栓保证工件 夹紧)
Tension
• The clamp load in the joint is the target of all tightening(夹紧载何 就是我们的拧紧的目标)
AC tightening technique
Why use bolted joints?为什么使用螺栓连
接
It’s so easy that a child can do it
• Easy and quick assembly(简单方便)
• Can be disassembled and reassembled(可以拆卸和重新装配)
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AC tightening technique
VDI 2230－使用范围
VDI 2230的应用非常广 泛，包括带60度法兰的 高强度螺拴，螺丝大小 从M4到M39。
它给出的是单螺拴连接 的分析指导。由多个螺 拴组成的连接，负荷首 先要被分配，使每个螺 拴上的负荷确定下来。
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The Joint Loaded by an Applied Force连接负载被一应用的力产生
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AC tightening technique
The Joint Loaded by an Applied Force
Zero clamp at the
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AC tightening technique
Question
What is the major difference between a bolted joint on one hand and a welded, glued or riveted joint on the other hand?
螺拴与连接件的关系
Βιβλιοθήκη Baidu
拉伸弹簧＋ 压紧弹簧
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连接件图
螺拴和连接的变形
压力
力
连接件压 缩
压缩量
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连接件图
拉力 螺栓拉伸
伸长量
螺栓连接的变形关系
夹紧力
预 紧 力
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AC tightening technique
THE BOLTED JOINT IS PRELOADED! And what is the consequence of this diffference? ONLY A SMALL PORTION OF THE EXTERNAL LOAD
IS TRANSFERRED TO THE BOLT (until the preload is exceeded) !只有很小的一部分外部负载被转移到螺栓上 (直到超过预加负载)
提供了一个有摩擦力的夹紧=>这将不会出现部件分离如果部件不能有 相互的位移
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螺栓连接的受力
剪切
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拉伸
一定要确保施加的扭矩达到最小需要扭矩
• 夹紧力一定要高于外部载荷
• 安全余量载荷的影响因素: – 振动 – 摩擦力的变化 – 连接件尺寸变化 – 拧紧精度