Cutting insert

Details Cutting insert Cutting insert

1996-12-13

1998-11-24

Pitts, Andrea L.

Cutters, for shaping

Including tool having plural alternatively usable cutting edges

With integral chip breaker, guide or deflector

407116, 407115, B23B 2722

Patent

active

058398570

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION



CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US national phase of PCT application PCT/DE95/00552 filed 21 Apr. 1996 with a claim to the priority of German application P 44 22 312.9 filed 17 Jun. 1994.


FIELD OF THE INVENTION

The invention relates to a cutting insert for machining having at least one top surface forming the cutting surface and peripheral side faces forming the free faces, the cutting surface having at least one raised chip-shaping element that extends as seen from above like a wedge toward the cutting edge.


BACKGROUND OF THE INVENTION

Cutting inserts with such chip-shaping elements are known for example from EP 0,066,091. The cutting inserts described there have at the cutting edge or the cutting corners a land of constant width behind which there is a steeply descending cutting surface region and a shallowly descending cutting-surface region. The chip-shaping elements lie in the last two cases on slightly descending cutting-surface regions. The chip-shaping element projects with its upper edge past the plane of the cutting edges or the cutting corners. The ascending surface is formed of curved side flanks that extend toward the cutting corner as a rounded region with a larger but not more closely defined radius of curvature.


OBJECTS OF THE INVENTION

It is an object of the present invention so to improve on the above-described type of cutting insert that, in machining operations wherein radically deformed chip cross sections are produced, the chip or the chip layers are separated from each other by the influence of a force from an element at a particular location so that the stable chip-cross section is weakened and the force exerted by the chip on the cutting insert is reduced.


SUMMARY OF THE INVENTION

This object is attained by a cutting insert according to claim 1 which is characterized in that the raised chip-shaping element has a width that increases uniformly away from the cutting edge along its longitudinal axis continuously in the region of ascending surfaces turned toward the cutting edge, the ascending surfaces being formed as generally planar side flanks which extend at an acute angle to each other, toward the cutting edge as well as upward, the upper edge being rounded along its full length, and a surface turned away from the cutting edge being formed as a descending flank and ending at the ascending surfaces.
Preferably the raised chip-shaping element not only locally lifts the passing chip from the cutting surface surrounding the element but also partially tears the passing layers of the chip transversely and longitudinally of the chip-travel direction to facilitate subsequent fracturing of the individual layers. The frictional forces that are produced are substantially less than in the known chip-shaping elements and the effect of the force on the cutting insert is reduced. Preferably these raised chip-shaping elements can be combined with other also trough-shaped recesses of different cutting edge formations on cutting inserts with different geometries.
The angle of ascent of the upper edge measured longitudinally relative to the plane in which the cutting corners lie or relative to the cutting edge is between 10.degree. and 45.degree., preferably 20.degree. to 35.degree.. The descending flank is a plane which has a negative angle of inclination of between 15.degree. and 40.degree., preferably 15.degree. to 30.degree. relative to the plane in which the cutting corners lie or relative to the cutting edge. Experience has shown that optimal results are obtained when the side flanks seen from above form a wedge angle between 15.degree. and 40.degree., preferably 20.degree. to 30.degree. and/or the radius of the rounded upper edge is between 0.1 mm and 0.5 mm. The length of the ascending flank seen from above at the upper edge is between 0.3 mm and 4 mm. In connection with the known angle of the ascending flank, this length is enough to effect the described layer separation with normal cut conditions. The chip-shaping element(s) are a

REFERENCES:
patent: D304949 (1989-12-01), Niebauer
patent: D305239 (1989-12-01), Niebauer
patent: 4487534 (1984-12-01), Reiter
patent: 5147159 (1992-09-01), Lowe et al.
patent: 5503507 (1996-04-01), Lowe et al.

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