The employee was additionally tightening a bolt using a T pipe in exchanging a mold of Machine 3. When he tightened it leaning his weight on the circle part of right illustration by hand, the pipe turned over and he lost a balance and fell backward. At that time, he hit his back of the head on the corner of a work table and was injured.
*The victim wore a helmet. But he hit the point below the helmet and was injured.