螺纹副摩擦力Friction in the threads
50 – 40 – 10 规则
541rule
螺栓头下摩擦力 Screw head friction 50%
产生夹紧力
Clamp Force
10%
90% 的扭矩用于克 服摩擦力
螺纹副中
Friction in the threads
40%
扭矩
100%
半线性区Semi-elastic area.
ΔT Δα
角度Angle
塑变区Plastic zone.
寻帽Finding 快速旋进Run down
最终扭紧Final
螺栓标识The Bolt Marking System
Manufacturer First figure = 1/100 of min tensile stress (N/mm2) 100* 8 = 800 N/mm2
施加的扭矩The applied torque is measured
夹紧力是我们的目标Clamp force
is our target
1 1
直接测量夹紧力的方法the way to measure clamp force
12
为了拧紧螺栓, 必须施加力以便拧紧螺母/螺丝
The applied torque is must
3
生产过程中的几种装配方法assembly
• • • • 焊接 粘接 铆接 用螺丝和螺栓拧紧
4
哪种装配方法最普遍？Which one is most common
• • • • 焊接 粘接 铆接 用螺丝和螺栓拧紧
?
5
使用螺丝和螺栓拧紧！Advantages with screws and bolts!
15
夹紧力取决于扭矩和其他因素-摩擦力
Clamping force is dependent of torque and other factors – mainly friction
• Fm= T/ (0.16P + (μg * 0.58 * d2) + ((Dkm/2) * μk)) 螺距Pitch 螺纹副Thread 螺栓头Head • 定义Definitions
50 %
50%
螺纹里加润滑lubrication
19
30%
摩擦力减小会导致...friction decrease
20 %
30 % 50 %
...过拧！Over clamp force
20
改变摩擦力 – 生锈的螺栓friction change-rusty bolt
生锈的螺栓rusty bolt
• •
螺栓标记Bolt marking 螺栓分级Screw classifications
7
什么是连接
What is a joiarts
螺母Nut
连接受到不同的外力The joint is exposed to different external forces
8
这种情况必须避免This must be avoided!
9
The thread creates the clamp force that holds the joint together
• Turning the nut or screw stretches the screw • The stretching of the screw clamps the parts together • The clamp force in the joint is the target of all tightening
40%
17
改变摩擦力 – 加润滑friction change-lubrication
螺纹里的润滑lubrication
18
扭矩和夹紧力的关系torque and clamp force
夹紧力Clamp Force
螺栓头摩擦力Screw head friction
20 % 30 %
螺纹副摩擦力Friction in the threads
But why? • • • • • • 设计简单Simplicity of design 零部件标准化Standardized 装配简单，拆卸方便（可逆）Easy assembly and disassembly 效率高High productivity 成本低COST efficient 可控（螺栓张力可控）well controlled
屈服点Yield point = %抗拉强度of tensile strength
(弹性区域的终点 The ‘end point’ of elastic range)
失效Failure
角度Angular displacement
螺栓扭紧过程定义Tightening cycle
基本定义definition：
基本拧紧技术
Basic tightening technique
1
内容安排
时间 13:30-14:15 14:15-15:00 15:00-15:15 15:15-16:00 16:00-17:00
2
内容 基本拧紧技术 扭矩与夹紧力 休息 拧紧策略 动静态扭矩
人员 All All All All All
1 0
螺纹紧固件
Threaded fasteners - Torque
夹紧力是我们的目标，但是很难测量，而扭矩很容易测量
Clamp force is what we aim at but it is difficult to be measured. Torque is easy to measure and to apply
STANDARD
失效不影响设备功能
13
施加100%扭矩，夹紧力的结果Applied Torque (100%) and resulting Clamp Force…
‘正常情况Normal conditions’
扭矩Torque 夹紧力Clamp Force
螺栓头摩擦力Screw head friction
10%
100 % 50% 40%
30°
Hard Joint
拧紧到目标扭矩角度小于30°Tightening angle below
扭矩Torque (Nm)
目标Target
啮合点Snug level
<30
角度Angle (degrees)
软连接Soft joint
软连接
扭矩Torque (Nm)
目标Target
Soft Joint
过拧紧Overshoot and Mean shift
T 过拧紧Overshoot
Target Hard Soft
中间飘移Mean Shift
贴合面
Snug level
Angle (φ )
27
抗拉强度和屈服点Tensile strength and yield point
强度Stress
抗拉强度Tensile strength
• Dkm = (dw + dh)/2
– μk
16
改变摩擦力 –塑料垫圈friction change-plastic washer
夹紧力Clamp Force
螺栓头摩擦力Screw head friction
20 % 40 %
螺纹副摩擦力Friction in the threads
40 %
塑料垫圈plastic washer 40%
拧紧到目标扭矩角度小大于720°
Tightening angle above 720°
啮合点Snug level
角度Angle (degrees)
over 720
Real joints
硬连接
30°
Hard Joint
拧紧到目标扭矩角度小于30°Tightening angle below
很少连接是硬连接Very few joints are below 30°
!
6
基本拧紧技术Basic tightening technique
• • • •
• • •
什么是连接What is a joint? 部件Parts 不同的连接Different joint types 不同的负载Different loads
扭矩、摩擦力和加紧力Torque, friction and clamp force 连接类型Joint types 抗拉强度和屈服点Tensile stress and yield point
21
扭矩和夹紧力的关系torque and clamp force
夹紧力Clamp Force
螺栓头摩擦力Screw head friction
0%
螺纹副摩擦力Friction in the threads
50 %
50 %
50%
生锈的螺栓rusty bolt
22
50%
硬连接Hard joint
硬连接
31
螺栓分级
Screw quality classification With torque indications
32
推荐力矩值
Recommended torque levels
33
螺栓连接的分级joint classification
CATEGORY ASSEMBLY CRITICITY Example NEEDS 1- TO ASSURE A CORRECT TORQUE Sun roof, plastic protection 2 - TO ASSURE THAT ALL SCREWS ARE TIGHTENED AT CORRECT TORQUE 3 - TO ASSURE THAT THE JOINT IS CORRECT Gear box fixture, Engine fixture 4 - TO ASSURE THAT ALL SCREWS ARE TIGHTENED AND ALL JOINTS ARE CORRECT