DE29919858U1 - Carbide drills - Google Patents

Description

Harald Schmid 3091

04.11.1999

Carbide drill bits

The invention relates to a hard metal drill with at least two cutting edges for hard or hardened materials.

There are two- and, more rarely, three-edged drills for hard or hardened materials that leave much to be desired in terms of drilling feed rates and tool life (service life).

The object of the invention is to provide a drill of the type mentioned above which has high and comparatively significantly improved feed rates with comparatively longer service lives

The object is achieved according to the invention by a three-phase drill bit, wherein the first, drilling phase, has an angle of 140 ± 1 to 20%, the subsequent second, middle phase, an angle of 110° ± 1 to 20% and the third run-out phase, an angle of 90° ± 1 to 20% and the run-out phase is comparatively short compared to the other two phases.

Advantageously, the first and second phases have substantially the same cutting lengths.

It is advantageous if the first angle is 140° ± 1 to 10%, preferably 140°, the second angle is 110° ± 1 to 10%, preferably 110° and the third angle is 90° ± 1 to 10%, preferably 90°.

The object of the invention is alternatively achieved by a two-phase drill bit, wherein the first, drilling phase has an angle of 140° ± 1 to 20%, in particular ± 1

up to 10%, preferably 140°, followed by the second phase limited by a radius, which merges seamlessly into the outer circumference of the drill.

For both solutions according to the invention, it is advantageous if the drill has 2 to 8 cutting edges, preferably 4 cutting edges

For a double-edged drill according to the invention, diameters of up to 3.0 mm are advantageously selected. For drills according to the invention with 3 or 4 cutting edges, diameters of 2.5 to 16 mm are particularly suitable, and for 6 to 8 cutting edges, diameters of 16 to 25 mm are particularly suitable. For the drill according to the invention with a two-phase drill tip, it is advantageous to select the radius with a diameter "D" of 0.5 D to D, preferably 0.5 D to 0.7 D.

It may also be advantageous to design the drill bit according to the invention as an attachment.

The invention will be described only with reference to two preferred embodiments, which are shown in the drawing. Herein, in schematic representation,

Fig. 1 the drill bit of an inventive
three-phase drill and

Fig. iThe drill bit of an inventive
two-phase drill.

The drill 1 according to the invention in Fig. 1 has an angle of approximately 140° as the drilling phase (first phase) 2 for good self-centering. To reduce the cutting pressure as much as possible, the drilling phase is followed by a middle phase (second phase) 3 of approximately the same length with an angle of approximately 110°. This is followed by a comparatively short third phase 4 as a protective phase with an angle of

a a a

a »·· a

a a a

about 90°. The protection phase is intended to prevent or largely avoid the corners breaking out.

The drill according to the invention is particularly suitable for hardened materials (approx. 50 to 70 HRC ₁ preferably 55 to 68 HRC). The drill is made of hard metal (solid hard metal). Ceramic and cermet can also be used as materials.

Another drill 5 according to the invention with the diameter "D" is shown in Fig. 2. This is a two-phase drill with a drilling phase 6 of 140° corresponding to the drill according to Fig. 1. According to the invention, the drilling phase is followed by a radius "R" with a circle center on the drill axis, which, for example, with a drill diameter of 6 mm, has a radius of 3 to 6 mm and, for example, with a drill diameter of 10 mm, has a radius of 5 to 10 mm, preferably max. 7 mm. In general, with a diameter "D", the radius following the drilling phase is dimensioned according to the invention to be 0.5 D to D, preferably 0.5 to 0.7 D.

The invention is not limited to the embodiments. The invention includes variants that will readily occur to the person skilled in the art after having become familiar with them.

The number of cutting edges can be selected between 2 and 8 depending on the drill diameter. Further advantageous embodiments emerge from the features of the subclaims.

Claims (10)

1. Drill made of hard metal with at least two cutting edges for hard or hardened materials, characterized by a three-phase drill tip, wherein the first, starting drilling phase has an angle of 140 ± 1 to 20%, the subsequent second, middle phase has an angle of 110° ± 1 to 20% and the third run-out phase has an angle of 90° ± 1 to 20% and the run-out phase is comparatively short compared to the other two phases. 2. Drill according to claim 1, characterized in that the first and second phases have substantially the same cutting lengths. 3. Drill according to claim 1 and 2, characterized in that the first angle is 140° ± 1 to 10%, preferably 140°, the second angle is 110° ± 1 to 10%, preferably 110° and the third angle is 90° ± 1 to 10%, preferably 90°. 4. Drill made of hard metal with at least two cutting edges for hardened materials characterized by a two-phase drill tip, wherein the first, drilling phase has an angle of 140° ± 1 to 20%, in particular ± 1 to 10%, preferably 140°, which is followed by the second phase delimited by a radius, which merges seamlessly into the outer circumference of the drill. 5. Drill according to claim 1 or 4, characterized in that it is a 2- to 8-edged, preferably 4-edged drill. 6. Drill according to claim 5, characterized by 2 cutting edges with a diameter of up to 3.0 mm. 7. Drill according to claim 5, characterized by 3 or 4 cutting edges with a diameter of 2.5 to 16 mm. 8. Drill according to claim 5, characterized by 6 to 8 cutting edges with a diameter of 16 to 25 mm. 9. Drill according to claim 4, characterized in that for a diameter of "D" the subsequent radius "R" is 0.5 D to D, in particular 0.5 D to 0.7 D. 10. Drill according to one or more of the preceding claims, characterized in that the multi-phase drill bit is designed as an attachment.