ねじの締付管理方法の比較

Abstract

In this paper, the torque and the angle control methods, which are most usually used in screw tightening, and the newly developed gradient control method are compared and a policy for the selection of them is discussed. For this purpose a tightening test machine which can test the above three methods is designed and manufactured. Firstly, using the machine, fundamental experiments are carried out taking account of the following factors : pitch of screw threads (A), surface treatment (B), lubrication (C) and tightening speed (D), and it is pointed out that the effect of the lubrication condition is especially significant. Secondly, in the case where the factors (A), (B) and (D) are fixed and the factor (C) is with or without lubrication, the three control methods are compared, and it is found that the dispersions of clamping force become greater in order of the angle, the gradient and the torque control methods. Finally, a new tightening method is presented, in which bolted joints are tightened with the torque or the angle control methods using the value of the torque or the angle found in the case of tightening them with the gradient control method, and this method is confirmed to be efficient.