What happened to the polygon after the chip removal drilling 1 meter length of the deep hole drilling and boring machine?

Structural defects of chip removal groove of bit body. Due to the structural defects of the bit body row, it is easy to make mistakes in the process of drilling and boring, which leads to the formation of polygons in the later stage. Deep-hole drilling and boring machine is used to process deep holes with aperture ratio (D/L) above 1: 6, such as gun barrels, gun barrels and machine tool spindles.