Cutting by use of rotating axially moving tool – Tool-support with means to permit positioning of the tool... – Pivotable tool
Patent
1986-10-27
1988-09-13
Bilinsky, Z. R.
Cutting by use of rotating axially moving tool
Tool-support with means to permit positioning of the tool...
Pivotable tool
408197, 408713, B23R 5100
Patent
active
047705710
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to the metal machining, and in particular, it deals with drills.
BACKGROUND ART
Known in the art is a drill disclosed in USSR Inventor's Certificate No. 718232 issued July 28, 1978 and published 1980, comprising a holder and a cutting member in the form of a pair of discs mounted in the holder eccentrically with respect to the axis thereof, the discs partly engaging each other with their end faces which have recesses to receive an insert for setting a desired diameter of drilling. This drill may be successfully used for counterboring. Since the cutting member of the drill comprises two round discs secured to each other, it cannot be used for drilling in a continuous body of material as the cutting edge of one disc at the center of the head portion of the drill is situated in the immediate proximity to the clearance face of the other disc. In drilling a hole in a continuous body of material, the root of chip (in the area where the chip has a high enough rigidity) bears against the clearance face of the cutting disc and the chip would get in between the engaging end faces of the cutting discs. The chip getting in between the discs hampers the cutting process, and causes a temperature increase in the cutting zone so that the drill life is reduced. In addition, the diametrical size of the drill is at rather a large distance from the head end face of the holder and is equal to about 2/3 R wherein R is the radius of the cutting disc. Therefore the diagonal of holder cross-section cannot exceed the diameter of the hole being machined in a plane drawn at a distance of 2/3 R from the center line of the cutting discs, i.e. the distance from the head end face of the holder to the center line of the cutting discs should be kept minimum possible so that the holder might have maximum possible cross-sectional area. A small cross-sectional area of the holder cannot ensure necessary rigidity of the drill.
It should also be noted that in machining holes in a continuous body of material only about one fourth of the whole circular cutting edge of each disc can take part directly in the cutting process (with one setting of the cutting member) so that the drill life is reduced as compared to penta- and hexahedral discs.
DISCLOSURE OF THE INVENTION
The present invention seeks to provide a drill with discs of a cutting member designed and arranged so as to increase the distance from a cutting edge of one disc to a clearance face of the other disc and to obtain the length of a diagonal of the holder cross-section to be close to the drill diameter and thus to improve the rigidity of the drill.
This is accomplished in a drill, comprising a holder and a cutting member in the form of a pair of discs mounted in the holder eccentrically with respect to the axis thereof and partly engaging each other with their end faces which have recesses for accommodation of an insert for setting a desired diameter of the drill, wherein, according to the invention, each disc of the cutting member has at least five facets disposed along the periphery thereof symmetrically with respect to the center line of the disc, the discs being mounted in such a manner that the angles of inclination of their facets with respect to the axis of the holder are equal to one another.
It is known that each facet of the disc is the clearance face of the drill and its intersection with the end face of the disc defines the cutting edge. Therefore, owing to the fact that the cutting discs are made with facets, at least with five facets, the distance from the cutting edge of one disc to the clearance face of the other disc is increased. Consequently the root of chip substantially cannot directly engage the clearance face of the cutting disc. Moreover, the chip can leave the cutting edge in the central part of the cutting member more easily since the direction of movement of chip is almost parallel with the clearance face of the disc. The cutting edge consisting of individual conjugated portions also contributes to enhanced chip bre
REFERENCES:
patent: 3688367 (1972-09-01), Bennett
patent: 4251172 (1981-02-01), Durand
patent: 4525110 (1985-06-01), Stosanovski
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