Cutting insert with trapezoidal indentations along the cutting e

Details Cutting insert with trapezoidal indentations along the cutting e Cutting insert with trapezoidal indentations along the cutting e

1994-06-10

1997-11-18

Rachuba, M.

Cutters, for shaping

With chip breaker, guide or deflector

B23B 2716

Patent

active

056880812

DESCRIPTION:

BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS

This application is the US national phase of PCT application PCT/DE92/01027 filed 7 Dec. 1992 with a claim to the priority of German application P 41 41 368.7 filed 14 Dec. 1991.


FIELD OF THE INVENTION

The invention relates to a cutting insert for chip-forming machining, in particular for rough machining of metallic workpieces with a high feed rate having a chip surface which is provided in the region of a cutting edge with indentations which are arranged in a row extending along the cutting edge, which interrupt same and which have a generally trapezoidal sectional shape parallel to the cutting edge and perpendicular to the chip surface with trapezoid sides open toward the chip surface.


BACKGROUND OF THE INVENTION

Cutting inserts of this type are known from the prior art, e.g. from EP 414,241. Such a cutting insert has indentations on its edge surface as well as on its chip surface which overlap in the region of the cutting edge so that the cutting edge is set back in the region of the indentations relative to the remaining portions of the cutting edge. The actual trapezoidal shape has sharp edges which are hard to maintain for long times. In addition even with this arrangement the friction as chips pass over it is considerable. Disadvantageously the cutting insert in this reference can only be used for a particular setup.
Further cutting inserts with indentations are known from German 2,849,610. As a result of the substantial width of the inserts at the actual cutting edge a substantially increased plastic deformation or stiffening of the passing chips is achieved. The indentations are in top view generally round to square with rounded transitions and corner regions in the chip surface. A comparable cutting plate is described in U.S. Pat. No. 4,447,175 where a row of concave recesses is provided along the cutting edge with the cutting edge uninterrupted. The recesses are generally rectangular seen in top view.
U.S. Pat. No. 3,973,308 also describes recesses that are in top view rectangular or even triangular and that also do not reach to the cutting edge but start in a region at a bevel of the cutting edge and that extend inward down into a chip groove. This embodiment also is intended to reduce the temperature and forces exerted on the chip surface during machining.
Similarly to reduce the thermal and mechanical load during machining operations German 3,731,426 suggests a cutting insert with a corrugated cutting edge where the chip surface is corrugated parallel and perpendicular to the cutting edge.


OBJECTS OF THE INVENTION

It is an object of the present invention to develop a cutting insert of the above-described type which has even at high feed speeds a stable guiding and diversion of the chips with minimal wear to the cutting edge. Furthermore the cutting insert should be simple in construction and also simple to make.


ACCORDING TO THE INVENTION

The solution is the cutting insert which is characterized in that the indentations have a chip-surface base extending at a negative chip angle or a 0.degree. chip angle for the case of an indentation with a positive chip angle. The chip surface in the region between the indentations at the cutting edge has a positive chip angle of at least 5.degree.. To avoid sharp-edge transitions between the indentations and the surrounding chip surface in the region of the cutting edge the transitions are preferably rounded, preferably with a radius from 0.3 to 3 mm.
This cutting insert causes a plastic deformation of the chip passing over it with minimal force and friction. The chip shaping as well as the chip guiding are positively influenced by the negative chip angle of the indentations. In general the negative chip angle of the indentations interrupting the cutting edge stabilizes the cutting edge so that high feed rates can be used without the danger of breaking off parts of the cutting edge. The trapezoidal section is not only clearly defined during manufacture of the cutting insert but can be made without great

REFERENCES:
patent: 4273480 (1981-06-01), Shirai et al.
patent: 4934879 (1990-06-01), van Barneveld
patent: 4988242 (1991-01-01), Pettersson et al.
patent: 5074720 (1991-12-01), Loqvist et al.

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