Cutting insert for drill
AssigneeSandvik Aktiebolag
InventorsJorgen Wiman, Ake Sjolander
Life of this patent
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Abstract
A cutting insert for a during includes a broken main cutting edge, the ends of which join respective additional edges of the insert by curved nose portions. Each curved nose portion forms a curved cutting edge defined by at least three sequentially arranged curved cutting edge segments defined by respective radii of different sizes. A first of the segments joins one end of the main cutting edge and has a first radius. The next segment has a radius of different length than the first radius and projects farther laterally than the first segment to perform a wiping function.
Claims10
Cutting insert for a rotary drill, comprising a body having a polygonal shape with substantially flat upper and lower surfaces, and edge surfaces adjoining the upper and lower surfaces;
- the lower surface having a smaller area than the upper surface to provide the insert with a positive cutting geometry;
- a first of the edge surfaces intersecting the upper surface to form a main cutting edge;
- the main cutting edge comprising short cutting edge portions converging from respective ends of the cutting edge and forming an obtuse angle with one another;
- at least one end of the first edge surface joining a second one of the edge surfaces, respectively, by a curved nose portion;
- the curved nose portion intersecting the upper surface to form a curved cutting edge defined by a plurality of sequentially arranged curved cutting edge segments having respective radii, the radii of adjacent ones of the segments being of different respective lengths.
A rotary drill bit comprising:
- a shaft defining a longitudinal axis of rotation, and a longitudinal front end;
- and
- a cutting insert mounted at the front end and comprising:
- a body having a polygonal shape with substantially flat upper and lower surfaces, and edge surfaces adjoining the upper and lower surfaces;
- the lower surface having a smaller area than the upper surface to provide the insert with a positive cutting geometry;
- a first of the edge surfaces intersecting the upper surface to form a main cutting edge;
- the main cutting edge comprising short cutting edge portions converging from respective end of the cutting edge and forming an obtuse angle with one another;
- at least one ends of the first edge surface joining a second one of the edge surfaces, respectively, by a curved nose portion;
- the curved nose portion intersecting the upper surface to form a curved cutting edge defined by a plurality of sequentially arranged curved cutting edge segments having respective radii, the radii of adjacent ones of the segments being of different respective lengths, wherein a first of the segments joints an end of a first of the short cutting edge portions, an adjacent one of the segments connected to the first segment and having a radius of different length than the first segment and projecting farther from the axis of rotation than the first segment.
Dependencies are inferred from the claim text.