Because of the indexer in the four-axis machining center and the arm descending during tool changing, the tool will probably hit the work piece in certain conditions.

• 四轴加工中心由于安装了分度盘,而盘式刀库在换刀时刀臂要下降一段距离,所以在一定的条件下就会在换刀时刀具与工件发生碰撞事故。