Cutting by use of rotating axially moving tool – With means to apply transient – fluent medium to work or product – Including tool with duct
Patent
1998-08-27
2000-02-29
Pitts, Andrea L.
Cutting by use of rotating axially moving tool
With means to apply transient, fluent medium to work or product
Including tool with duct
408 57, 408223, 408230, B23B 2710
Patent
active
060301554
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention is related to a drilling tool for machine tools and a method for the production thereof.
BACKGROUND OF THE INVENTION
A drilling tool of this type is known, which comprises a drill body having at least two chip transport grooves which are delimited at their flanks by helical ribs and a cutting head which is disposed at the front face side of the drill body. The cutting head has two segment portions which are radially outwardly delimited by partially cylindrical circumferential surfaces and which are seperated from each other by chip spaces which end in the adjacent chip transport grooves in the direction of chip flow and which are aligned essentially parallel to the tool axis. Further, the cutting head comprises at least two cutting inserts which are each disposed in a recess of the segment portions in the region of an essentially axially parallel radial chip breaker face, preferably with the face aligned to this, and which each have at least one active cutting edge which protrudes axially over the cutting head, wherein the chip breaker faces each end in a helical flank of the adjacent chip transport groove at a transition point in the direction of chip flow.
By a specific alignment of the cutting inserts which partially overlap in the active region of their cutting edges it is ensured that the lateral forces present at the cutting edges during drilling are essentially compensated by each other, so that a bore may be made in a workpiece essentially without guidance. The chip spaces, which extend axially parallel in the cutting head and which have a triangular cross section, merge in the direction of chip flow into a comparatively steep helical chip transport groove, which is also of triangular cross section. The chip transport grooves are delimited at their edges by ribs which on the one hand serve to guide the drill within the bore and on the other hand serve to delimit the chip transport grooves. The chips are mainly forced out through the chip transport grooves under the action of a coolant and lubricant which is supplied through the drill body. By the design of the ribs to be relatively broad it is attempted to prevent that the chips exit the chip transport grooves and distribute themselves over the circumference of the drill body, since this could cause the chips to be fused to the bore wall and the drill body, damaging the bore and the drilling tool. A further problem consists in that the chip space forms in the region of the cutting inserts, which are displaced radially inwards with respect to the circumference, a chip space of triangular cross section which tapers in the direction of chip flow in a funnel-like fashion. This leads to the circumstance that the chips may be formed to be relatively broad upon their creation and then have to be forced into the chip transport groove necessitating deformation work. By this a large part of the thrust imparted to the chips during the cutting process is lost in deformation work. Furthermore, the deformation forces are partially converted into transverse forces, which causes a radial deflection of the drilling tool and therefore a degradation of the drilling efficiency and bore quality.
Based on this it is an object of the invention to develop a drilling tool which ensures an efficient and nearly lateral force-free chip flow, and which therefore may be used to create comparatively deep bores. A further object of the invention is to develop a method for the production of the drilling tool according to the invention.
SUMMARY OF THE INVENTION
The solution according to the invention is based foremost on the recognition that a chip deformation, which leads to a chip compression and lateral forces, must be avoided in the region of the chip spaces and the following chip transport grooves. In order to achieve this goal, the following features are proposed according to the invention: flanks by helical ribs, the drill body, outwardly delimited by partially cylindrical circumferential surfaces and which are seperated from each
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Alber, P., and Guehring, K.: Schleifen von Wendelnuten ins Volle (1981); pp. 723-727.
Baxivanelis Konstantin
Scheer Gerhard
Komet Praezisonswerkzeuge Robert Breuning GmbH
Pitts Andrea L.
Smith Monica
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