Drill having radially overlapping indexable cutting inserts
AssigneeSeco Tools AB
InventorFredrik Lamberg
Life of this patent
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Abstract
A drill includes a shank, a central insert and a peripheral insert. The shank defines a central axis of rotation and has pockets which carry the peripheral and central inserts. Chip flutes are formed in an outer periphery of the shank for conducting chips cut by the respective inserts. The peripheral insert includes a first operative cutting edge, and the central insert includes a second operative cutting edge which overlaps the first cutting edge at an overlap region. The central insert forms a rake surface adjacent to the second cutting edge. The rake surface includes a first portion disposed at the overlap region, and a second portion disposed at the axis of rotation of the shank. The first portion has a larger rake angle than the second portion.
Claims8
A drill comprising a shank, a central insert, and a peripheral insert;
- the shank defining a central axis of rotation and having a central pocket receiving the central insert, a peripheral pocket receiving the peripheral insert, a pair of chip flutes extending rearwardly in an outer periphery of the shank from respective ones of the pockets for conducting chips cut by the central and peripheral inserts, respectively;
- the peripheral insert including a first operative cutting edge projecting laterally outwardly beyond the shank to form a diameter of a hole cut by the drill;
- the central insert being substantially square and including a second operative cutting edge overlapping the first operative cutting edge at an overlap region spaced radially from the axis of rotation, the second operative cutting edge extending inwardly past the axis of rotation, the central insert forming a rake surface adjacent to the second cutting edge, the rake surface including a first portion disposed at the axis of rotation and a second portion disposed at the overlap region, the second portion having a larger rake angle than the first portion.
A cutting insert adapted for use in a drill, comprising a body of substantially square shape;
- the body having upper and lower parallel generally planar surfaces, and side surfaces interconnecting the upper and lower surfaces;
- intersections of the upper surface and the side surfaces forming cutting edges;
- the lower surface having a smaller cross sectional area than the upper surface, whereby the insert has a positive cutting geometry;
- the body defining four corners each having a bisector, the corners forming parts of the cutting edges, and each corner having a rake surface;
- wherein a portion of the rake surface disposed on one side of a respective bisector has a larger rake angle than a portion of the rake surface disposed on the other side of that same bisector.
Dependencies are inferred from the claim text.