Cutting by use of rotating axially moving tool – Tool of specific diverse material
Patent
1989-11-13
1992-03-10
Howell, Daniel W.
Cutting by use of rotating axially moving tool
Tool of specific diverse material
408227, B23B 5102
Patent
active
050945718
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a drill manufactured from a substantially rod-like blank containing high speed steel. The invention also relates to a method for producing a drill according to the invention.
Drills of the kind meant here are intended for drilling primarily metal and are cylindrical in shape and include a pointed tip which is intended to be inserted into the material to be drilled and cutting edge-parts located in the vicinity of said drill tip. In this regard, slightly different requirements are placed on the drill material in the radial direction of the drill cross-section. The centrally located parts of the drill, the drill tip, are required to have a high compression strength and wear resistance. In addition to being wear resistant, the outer parts of the drill are also required to have a high temperature stability, because of the high relative speeds between the outer drill parts and the material being drilled.
Drills of this kind are manufactured from high-speed steel-rod, although optimum regard is not paid, however, to the aforesaid variation regarding the requisite material properties. This will often result in the use of a more expensive material than is actually required.
The present invention relates to a drill in which the properties of the drill material vary radially in the cross-section of the drill, and in which the properties of the material have been adapted to occurrent stresses as described hereinafter.
According to the invention, at least part of the drill material, with regard to its composition, can be selected with regard to desired material properties and not, as is usual, also with regard to the working properties of the material, primarily the hot working properties thereof. This will also enable very high contents of alloying substances to be used.
The invention thus relates to a drill produced from a substantially rod-like blank which contains high speed steel. The drill has at one end thereof a pointed tip which is intended to penetrate the material to be drilled, and is preferably a helical-type drill which includes cutting edges which extend essentially from the center part of the drill tip to the periphery of the drill cross-section, and also at least one radially open groove which extends helically along the drill, for the removal of chippings.
The inventive drill is particularly characterized in that the blank, and herewith also the drill in cross-section, comprises a steel central part which is adapted to exhibit high compressive strength and which forms the outer part of the drill tip, and a concentric, outer layer of high speed steel which is adapted to exhibit high thermal stability and which is applied by means of a casting technique.
The invention will now be described in more detail with reference to an illustrative embodiment thereof, shown in the accompanying drawing, in which:
FIG. 1 is a side elevation of a drill constructed from a rod-like blank made in accord with the present invention; and
FIG. 2 is a section taken through the plane 2--2 of the drill in FIG. 1.
According to the invention the drill blank, and therewith also the drill, includes, in cross-section, a central part which is adapted to exhibit high compressive strength and to form, inter alia, the drill tip. The requirement of thermal stability is not especially accentuated in this case. In the case of slightly simpler and less expensive drills, the central drill part may comprise carbon steel, i.e. not necessarily high speed steel. In the case of high performance drills, however, it is preferred in many cases to produce the central part of the drill from high speed steel, although not necessarily a high speed steel which possesses high thermal stability.
Furthermore, in accordance with the invention, the said outer layers of the drill comprise high speed steel, although a somewhat simpler high speed steel can be accepted in the case of simpler and less expensive drills. In the case of high performance drills, a high speed steel possessing very high thermal stability is preferably
REFERENCES:
patent: 2240840 (1941-05-01), Fischer
patent: 2351827 (1944-06-01), McAllister
patent: 3017790 (1962-01-01), Werle
patent: 4813823 (1989-03-01), Bieneck
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