Subterranean cutting tool structure tailored to intended use

摘要

A mill cutting structure is differently configured in three zones. Those zones are the center, the outer edge and in between. At the center has highly wear resistant material that has good temperature bond strength and high impact resistance. The outer periphery can have a material that is highly resistant to wear and impact. In between can be inserts such as used in the Metal Muncher® mills using sintered carbide shapes that resist tracking and create a chipping rather than a grinding action. The shapes should have high edge retention capability and shapes such as a double sided pyramid can be used. The wear patterns of prior designs are addressed to allow longer and faster milling of the fish.

主权项

1. A mill for milling subterranean tools or tubulars, comprising:
a body having a cutting face for tandem rotation with said body having a plurality of radially non-overlapping cutting zones when viewed on any given radial line passing through all said cutting zones and inserts disposed on a lowermost central zone of said body having a circular border to engage the tool or tubular to be milled wherein inserts in said central zone have different shapes than all said inserts in an adjacent radially surrounding intermediate zone; said cutting face further comprising a peripheral zone adjacent radially to said intermediate zone with blades extending starting from outside said central zone and extending over at least one of said intermediate and peripheral zones.