Cutters – for shaping – Including tool having plural alternatively usable cutting edges – With integral chip breaker – guide or deflector
Patent
1998-07-23
2000-06-27
Pitts, Andrea L.
Cutters, for shaping
Including tool having plural alternatively usable cutting edges
With integral chip breaker, guide or deflector
407 36, 407 41, B26D 125
Patent
active
060799129
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a cutting insert for workpiece machining with at least one main cutting edge for roughing and with an adjacent auxiliary cutting edge for finishing.
BACKGROUND OF THE INVENTION
European 0,117,400 describes a nonagonal indexable cutting plate that has on its lower and upper sides several main and auxiliary cutting edges of different lengths and that has the form of an equilateral triangle with symmetrically beveled-off corners, the main cutting edges lying in the region of the beveled-off corners and being shorter than the secondary cutting edges. In order to make a large number of usable cutting edges in a small cutting insert it has been suggested to make the ratio of the lengths of the main cutting edges to the lengths of the secondary cutting edges between 1:1.5 and 1:3 and to merge the main cutting edges via rounded corners with the auxiliary cutting edges, the radii of the rounded corners generally corresponding to the radii of a perimeter circle of the indexable cutting plate.
OBJECT OF THE INVENTION
It is an object of the present invention to provide a cutting insert for combined roughing and finishing by means of which one can get a high surface finish. In particular the cutting insert should be usable for planar milling of gray castings.
SUMMARY OF THE INVENTION
This object is solved by the cutting insert according to the invention in that the auxiliary cutting edges which extend to a planar free face, are convexly curved. In this manner an arcuate auxiliary cutting edge is produced for finish machining and that produces a cutting depth of for example 0.5 mm and a good surface quality.
According to the invention the auxiliary cutting edge is arcuately curved at a radius between 40 mm and 50 mm.
According to a further embodiment of the invention a chip-shaping groove, preferably a concave-section chip-shaping groove, extends on the cutting surface along the entire length of the auxiliary cutting edge and parallel thereto. This chip-shaping groove, which directly adjoins on the auxiliary cutting edge, produces when installed in a tool holder positive to neutral cutting angles both axially and radially. Preferably the auxiliary-edge cutting angle is between 10.degree. and 20.degree., preferably 15.degree.. The radius of the chip-shaping groove is between 0.5 mm and 0.8 mm.
According to a further embodiment of the invention the chip-shaping groove extends to the transition region between the auxiliary cutting edge and the main cutting edge. The main-edge cutting angle is positive, preferably up to 8.degree..
According to a further feature of the invention the cutting insert has a central raised cutting-surface plateau that is spaced from the highest point of the cutting edges. This produces a shape that produces edge lines on the cutting surface at a spacing from the cutting edges at respective angles. The central raised cutting-surface plateau has in particular the advantage that the cutting insert can be made two-sided since then alternatively the upper or the lower cutting-surface plateau can be used as mounting surface on the seat of a tool holder for clamping it in position. Preferably the cutting insert has a generally uniform hexagonal shape with three main cutting edges and three auxiliary cutting edges that delimit the cutting surface, preferably with two parallel cutting surfaces to produce overall six main and six auxiliary cutting edges.
In order to separate the machined chip produced by the main cutting edge effectively according to a further embodiment of the invention a chip-shaping element, preferably formed as a nose-shaped extension of the central raised cutting-surface plateau, is provided generally at the level of a perpendicular to a center of and spaced from the main cutting edge. The projection has a generally triangular planar top face level with the plane of the cutting-surface plateau and having a point directed at the main cutting edge and from which point extend adjacent planar side flanks to the cutting surface, pre
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UDDDEX Stirnfraser Mit Wendeplatten published by Uddeholms Aktiebolag, Sweden, dated Apr. 10, 1964.
Dubno Herbert
Ergenbright Erica D.
Pitts Andrea L.
Widia GmbH
Wilford Andrew
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