本帖最后由 pengzhh 于 2014-3-26 15:00 编辑
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Does it matter whether you tighten the bolt head or the nut? Normally it will not matter whether the bolt head or the nut is torqued. This assumes that the bolt head and nut face are of the same diameter and the the contact surfaces are the same (giving the same coefficient of friction). If they are not then it does matter. Say the nut was flanged and the bolt head was not. If the tightening torque was determined assuming that the nut was to be tightened then if the bolt head was subsequently tightened instead then the bolt could be overloaded. Typically 50% of the torque is used to overcome friction under the tightening surface. Hence a smaller friction radius will result in more torque going into the thread of the bolt and hence being over tightened. If the reverse was true - the torque determined assuming that the bolt head was to be tightened then if the nut was subsequently tightened - the bolt would be under tightened.
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