Torque-Add-Angle Control Approach Study For Bolt-Joints Of Automotive Key Components

There are a lot of bolt-joints failure problems based ontradition empirism design in automotive industrial. The properclamping force could overcome working load and improve the jointfatigue life.For light weight requirement, we need to change the frontknuckle material from ductile iron to aluminum. So the oldstrategy of torque only should be re-designed to adapt thischange. In order to control the clamping force scatter, we alsowant to use torque adding angle to replace the old design(torqueonly).It should cover all torque development detail, such asparameter configuration, validation test and statistic method. This paper studied the several factors impacting clampingforce included different friction coefficient of bolt-jointsurface and tightening speed.The whole torque development process included setting updesign limit by torque to yield method, statistic analyse byWeibull function, torque process parameter configuration,validation test, setting up the bench test, etc.The test result show the torque add angle control could bebetter than torque only control as of smaller scatter ofclamping force. This complete development process could behelpful to improve reliability in bolt joints of automotive keycomponents and driving safety.