Cutting by use of rotating axially moving tool – Tool or tool with support – Having stepped cutting edges
Patent
1997-06-09
1999-10-19
Bishop, Steven C.
Cutting by use of rotating axially moving tool
Tool or tool with support
Having stepped cutting edges
407114, 408230, 408233, 408713, B23B 5102
Patent
active
059677104
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a drilling tool for drilling holes in solid metal, with a base body which contains at least one chip flute, with at least one replaceable cutting insert on the end surface of the base body located in a recess on the end of a chip flute, and with a blade which is preferably formed by two cutting edges which form an obtuse point angle with one another.
2. Background Information
In general usage, such drilling tools are also designated indexable insert drills.
During drilling work with such indexable insert drills, the chips are basically removed from the cutting edges after they have been bent into a curved shape. The curvature of the chip is caused by the different cutting speeds at individual points or areas of the cutting edges. Basically, the chips flow radially inward from the wall of the boring toward the axis of the drilling tool.
Such drilling tools of the prior art are equipped with replaceable cutting inserts, the faces of which carry chip shaping steps. The chip shaping steps on the faces are oriented approximately parallel to the major cutting edges (European Patent No. 0 181 844 B1), even if the chip shaping steps are hump-like structures in the manner of spot-like projections which project from the rake faces (U.S. Pat. No. 4,215,957 A). The chip shaping is conventionally also achieved by placing obstacles in the path of the chip as it is being removed. As a result of these obstacles, the chip is plastically deformed and immediately deflected in a new direction.
OBJECT OF THE INVENTION
The object of the invention is to provide a drilling tool of the type described above with chip shaping devices which promote the removal of the chips via the chip flutes.
SUMMARY OF THE INVENTION
The invention teaches that this object can be accomplished if the rake face of the blades contains chip shaping ribs located next to one another which act in the manner of runners for the chips, which chip shaping ribs, in the vicinity of the blade or of the cutting edges are oriented approximately perpendicular to the cutting edges, and from there the chip shaping ribs extend in the direction of chip removal with a curved profile with regard to their installed position radially inward toward a flank area of the insert, which flank area is close to the axis of the drilling tool. The reset replaceable inserts are each located in the end of a recess on the end surface of a drill base body, and are realized so that their chip surfaces contain chip shaping ribs which are located next to one another which act like runners on which chips slide. In the vicinity of the cutting edges of the indexable insert, the runners are oriented approximately perpendicular to the cutting edges, and from there run approximately in the chip removal direction on a curved path relative to their installation position, radially inward toward a flank area of the insert. The curved path of the chip shaping ribs or grooves is thereby selected so that it corresponds largely to the natural or optimal removal direction of the chip. This chip removal direction is not maintained with absolute reliability during drilling. Various factors which are due to changing advance speeds, the material of which the workpiece is made, etc., can cause the chip to deviate from its ideal removal direction, with the consequence that the chip spiral formed is not removed correctly from the chip space, and in particular can generate a great deal of friction. The chip shaping ribs claimed by the invention prevent this undesirable effect by promoting the removal of the chips along a curved path which runs radially inward toward the axis of the drill. The chip shaping ribs force the chips being removed to travel in the direction in which they are being removed from the cutting edges. In particular, the chip shaping ribs or grooves reflect the shape of the chips, which results in practically an automatic guidance. An additional advantageous effect of this shaping of the chip in the manner of
REFERENCES:
patent: 4215957 (1980-08-01), Holma et al.
patent: 5688083 (1997-11-01), Boianjiu
patent: 5695303 (1997-12-01), Boianjiu et al.
patent: 5800100 (1998-09-01), Krenzer
Bishop Steven C.
Kennametal Hertel AG Werkzeuge + Hartstoffe
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