螺丝紧固扭力控制资料.ppt

Atlas Copco ToolsWhy threaded fasteners?Atlas Copco ToolsTensile Load vs.Shear LoadShear LoadShear LoadTensile LoadTensile LoadClamping forceAtlas Copco ToolsThis must be avoided!Shear LoadShear LoadTensile LoadTensile LoadAtlas Copco ToolsMeasuring the tightemingWe measure theapplied torqueWe WANT to measurethe clamping forceAtlas Copco ToolsTorque T=Fx xr2rFTarFTbTa=2FrTb=Frwhich gives Ta=2 TbAtlas Copco ToolsRelationship between applied Torqueand resulting Clamp ForceFriction in the threadsClamp ForceFriction under the bolt head50%10%40%Atlas Copco ToolsRelaxationThe material relaxes and you risk to loose clamping force!TimeAtlas Copco ToolsTorqueAngleSnug levelTorqueAngleSnug levelHard Joint 720 deg(ISO 5393)X NmX Nm 720 degAtlas Copco ToolsHard and Soft jointsTargetMean ShiftTorqueAngleOver ShootSnuglevelHardSoftAtlas Copco ToolsMean Shift compensationTorqueTime orAngleTarget torqueThis difference givesMean Shift and theneed for a qualitycontrol stationHard jointSoft jointAtlas Copco ToolsTorque OKTorqueAngleTorque=OKAtlas Copco ToolsTorque and Angle OKTorqueAngleTorque=OKAngle=OKAtlas Copco ToolsTorque OK,Angle LowTorqueAngleTorque=OKAngle=LowTorque=OKAngle=OKAtlas Copco ToolsTorque OK,Angle HighTorque=OKAngle=HighTorque=OKAngle=LowTorque=OKAngle=OKTorqueAngleAtlas Copco ToolsStatic TorquePower ToolOutputTorque(Nm)92949192949292X=92,43s=1,13StaticTorque (Nm)103 106 103 100 100 103 100X=102,14s=2,27T(Nm)Time20406080100110120Tool outputStatic torqueThe initial(static)friction is higher than the dynamicAtlas Copco ToolsThe Bolt Marking SystemManufacturerFirst figure=1/100 of min tensile stress(N/mm2)100*8=800 N/mm2 Second figure=relation between tensile stress and yield 0,8=80%Multiply the two figures to get the yield stress 800*0,8=640 N/mm2 Atlas Copco ToolsTensile Stress/Yield StressStressAngular displacementTensile stress100*8=800 N/mm2Yield stress800*0,8=640 N/mm275%YieldFailureAtlas Copco ToolsThread types MMetric UNFUnified fine threads UNCUnified coarse threadsM6=6mmTorque recommendation(short example)See table page 9 in the catalougeBolt gradeThread5.88.810.9 M30,77Nm1,20Nm1,70Nm M66,10Nm9,80Nm14,0NmM1029,0Nm47,0Nm65,0Nm