indexable cutting insert

Details indexable cutting insert indexable cutting insert

1995-12-11

1998-05-26

Howell, Daniel W.

Cutters, for shaping

Including tool having plural alternatively usable cutting edges

407114, B23B 2722

Patent

active

057555362

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The cutting edge on indexable cutting inserts, which are used in rotary cutters or milling tools, is subject to a number of different types of wear. One type of wear is that material is gradually removed from the flank, beginning at the cutting edge, and over the course of time this wear mark, which thus becomes visible, progresses farther and farther over the flank. In the region of the flank wear, the clearance angle is negative, and therefore as the flank wear progresses the required cutting and feeding force increases. As soon as the wear mark has attained a certain extent, which is approximately 0.3 to 0.5 mm measured from the cutting edge, the indexable cutting insert is considered to be worn and is placed with a new one.
The distance covered by the tool in engagement with a workpiece until the end of the life of the cutting edge is conventionally called the wear distance. Under otherwise identical material conditions, the wear distance could in principle be improved by enlarging the cutting wedge angle, because in that way the cutting edge contains more material and lasts correspondingly longer under the wear limit is reached. However, an enlarged cutting wedge angle is achieved at the cost of the clearance angle and/or flank angle so that the cutting forces and/or feed force rises. Both of these are undesired, and therefore the cutter geometry is always a compromise between the cutting and feed forces on the one hand and the wear distance on the other.
European Patent Disclosure EP-A 0 416 901 discloses an indexable cutting insert which has a flat base, a flat top spaced apart from the base, and a side wall arrangement extending between the base and the top. The side wall arrangement is divided by a sharply bent edge, which extends at an acute angle to the cutting edge, into two flat portions that are at different angles from the top. The sharply bent edge merges into the cutting edge, so that when an indexable cutting insert is installed in a basic milling body, the clearance angle at the leading end is formed by the portion located above the sharply bent edge. The clearance angle at the trailing end is created by the second portion. In this way, even if there is a positive axial angle, the clearance angle is intended to be kept substantially identical along the cutting edge. There is no intent of attaining a lengthening of the service life by means of this geometry.
An undercut disk miller of natural steel is known from "Werkstattblatt 516", Carl Hanser Verlag, Munich, 1970. The form of each tooth of the disk miller has a recessed second flank, so that the miller is sufficiently free opposite the pitch circle, which makes regrinding of the teeth easier. The width of the first flank directly adjoining the cutting edge is substantially larger than the wear limit, because otherwise the regrinding described in this reference would not be possible.
For soldered-in cutting inserts, German Patent 877 531 also discloses forming a projection by grinding, so that the flank protrudes from a region of the hard-metal cutting insert located below the flank. In this case, however, the clearance angle and the angle that the region located below the flank forms with the vertical are of equal size. The lug is intended to protrude 0.4 mm or more.


SUMMARY OF THE INVENTION

Based on this prior art, it is the object of the invention to create a cutting insert that has a longer wear distance with an otherwise identical geometry of the cutting edge.
In the new cutting insert, the entire region of the side wall arrangement adjoining the cutting edge no longer forms the flank; instead, only that part located between the cutting edge and the setback provided in the side wall arrangement does so.
As a result of this provision, it is attained that the flank wear, measured in the direction at right angles to the cutting edge, is limited to the region between the cutting edge and the setback. The feeding force, compared with a cutting insert lacking the setback, thus remains within certain maximu

REFERENCES:
patent: 4588332 (1986-05-01), Komanduri
patent: 4627317 (1986-12-01), Komanduri
M. Barash, "Production Technology Abroad", Manufacturing Engineering, Mar. 1980, p. 53.
Brochure "Turning Tools" from SANDVIK Coromant, 1984, p. 32.
"Schneidplatten--Sims wahrt Schueidfahigkeit", Werkstatt und Betrieb 118 (1985) 4, p. 188.
Brochure "ISCARMILL HELIMILL" from ISCAR, Oct. 1991.
Drawing No. 6388842/1 of PLANSEE--TIZIT, Jun. 1992.
Drawing No. RW 282400002 of KOMET, Feb. 1987.
Werkstattblatt 516 (Gruppe E), by Carl Hanser Verlag, Munchen, 1970.
Transactions of the American Society of Mechanical Engineers, Bd. 107, Nr. 2, May 1985, New York (p. 100)--Komanduri & Lee "The Ledge Tool: A New Cutting Tool INsert".

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