Abstract
The tightening of bolted joints is of vital importance to many engineers in the mechnical industry. The impact-wrenching is known as one of the most practical methods for the tightening of bolted joints, but few studies about the hammering impact have been made. This study investigated the percussive point of the spanner which gives an impact to tighten bolted joints to obtain the effective tightening force. Author found the precise formula to obtain the effective tightening force which acts on the bolted joints by impacts. The formula is r = K√Ms/Mh, where r is the distance between the percussive point and the rotatory axis of the spanner, K is the radius of gyration, Mh is the mass of the hammer, and Ms is the mass of the spanner. The experimental results agree well with the theoretical values.
