WO2012072652A1

WO2012072652A1 - Drilling tool for machining crp materials

Info

Publication number: WO2012072652A1
Application number: PCT/EP2011/071326
Authority: WO
Inventors: Ingo Von Puttkamer; Dominik Gerlach
Original assignee: Gühring Ohg
Priority date: 2010-11-29
Filing date: 2011-11-29
Publication date: 2012-06-07

Abstract

A drill intended for hard materials is described, with solid regions divided by flutes and with at least two main cutting edges which run tangentially with respect to the external periphery of the drill diameter, with transition to the chisel edge. Starting from the chisel edge and proceeding in a radial direction outwards towards the external diameter of the drill, the main cutting edge is at least in sections concave.

Description

Drilling tool for cutting CFK materials

The invention relates to a drilling tool for cutting Kohlestofffasernverstärketen

Plastic, such as carbon fiber reinforced plastic (CFRP)

The development of carbon-fiber reinforced plastic is moving towards materials with higher strength and greater rigidity. Thus, in aircraft the carbon fiber reinforced plastic, such as carbon fiber reinforced plastic (CFRP) is increasingly used.

In addition, when processing materials such as e.g. Steels HSS drills with drill tip geometries with a sloping in a longitudinal section through the drill under a radius

Major cutting profiles are known, such as the so-called "Racon Point" geometry (Radius-Conical, i.e. the radius extends over the entire length of the main cutting edge), or the Bickford-Point geometry (the radius extends only over the outer one

Main cutting section, while a central section with a linear main cutting path forms a good centering point).

US Pat. No. 3,443,459, for example, describes a drill having a main cutting edge in a plane parallel to the drill bit axis, in which the main cutting edge drops from the drill tip with a radius to the minor cutting edge and tangentially into the drill bit

Bolnemmfang passes so that a sharp cutting edge is completely bypassed.

In contrast, US Pat. No. 1,309,706 describes a drill with a main cutting profile, in which the main cutting edge follows a radius in an outer section in a plane defined by the drill axis and the cutting corner and extends linearly in a central section. The transition secondary cutting edge - main cutting edge is not tangential, but at a certain angle. However, the remaining cutting corner is thus at least much duller than conventional drills with a straight main cutting path in the above plane. These embodiments of the main cutting edge in addition to avoid the sharp

Cutting corners especially in the outer and thus highly loaded areas to an extension of the main cutting edge or to a reduction in per unit length of

Main cutting edge to perform cutting work.

On this basis, it is an object of the invention to provide a drill that is optimized for cutting carbon fiber reinforced plastic, such as carbon fiber reinforced plastic (CFRP) and promises low costs and high durability and Zespanungsleisrungen low cost.

This object is achieved with the features of claim 1.

According to the invention, the per se known merlanal of a main cutting edge, which runs continuously convexly from the cutting corner in the axial direction under a radius, is first transferred to drills with a sharpening. Due to the main cutting path according to the invention with a taper, it is now possible, the geomeü-related advantages - avoiding a sharp cutting edge, extension of the main cutting edge and reducing the load per main cutting length unit, especially in the outer region and reducing the pressure in

Center - to use.

Earlier approaches were directed, as described above, to counteracting wear on the cutting corner by selecting a particularly hard material, which, however, often led to premature breakage even at relatively low cutting powers or cutting values. Also, the compromise of selecting a medium-hard and tough material using the cast-root geometry did not lead to satisfactory results in terms of long

Lifetime or distances and high scores.

The carbon fiber reinforced plastic (CFRP) tends to delamination to a greater degree. Even when breaking through the last layer with the remaining cross-section of a generic drill, the central fiber is ripped. To avoid this, the free surface is sharpened in a drill with a Racon Point geometry in Zemtrumsbereich, thus shortening the transverse edge and the pressure in the center is reduced, thereby avoiding the emergence of individual chamfers when breaking the last layer is avoided with the residual cross-section ,

The drill material is so-called. Ceimets, Schneidcerceriks and hard metals, e.g. based on WC-TiC-Co.

With regard to the course of the main cutting edge, however, not only a main cutting edge extending in a plane parallel to the drill axis under a radius is conceivable, but also other continuously convex curvatures, such as, for example, a parabolic or hyperbolic curvature

In this case, the drill according to the invention has a tangential main cutting profile, i. the main cutting edge is fully tangential to the drill circumference. In comparison one

Tip area with a cutting edge that shortens the main cutting edge lengthens the usable tip area of a tangential major cutting edge. Due to the tangential passing main cutting edge, the heat dissipation improves, thereby reducing the thermal overload and the mechanical stress is reduced.

The smooth transition of the main cutting edge into the outer circumference of the drill diameter causes a reduction in wear, since the working area of the cutting edge at the outer circumference has the highest stepping speed and prevents delamination since the diameter to be drilled is slowly reached or drilled by the extended tip region.

In the embodiment according to claim 2, the main cutting also has a Ausspitzung in the central portion. At the upper end of the cutting edge, the taper sharpens the transverse cutting edge of the drill and increases the area of the groove to reduce the pressure in the center of the drill. The main cutting edge on the cross cutting edge has an additional chip and an open surface, whereby the main cutting edge in the center of the drill receives a concave shape. This is to reduce the pressure on the drill center, thereby avoiding breakage of the colloid-fiber reinforced plastic material as it exits the bore.

With the sharpened chisel edge, it is also possible, relatively large

Insert drill core diameter and thus increased bending strength and

To achieve torsional rigidity of the tool.

The geometry according to the invention can be used with straight or spirally grooved drills. As an open-plan grinding, a substantially cone-shaped bevel or a bevel with divided open surfaces is suitable in the manner of a 4-surface grinding. Several surfaces together form the free surface of the convex main cutting edge and the concave main cutting edge has at least one free surface. Further geometry-side

Further developments are useful only because of the properties of the selected drill material or only allow further optimization of the selected material.

Thus, the bolirer advantageously has a small Spanwinlcel in the area of Querscimeide. By the small Spanwinlcel an increase of the stability of the cutting wedge can be achieved.

The Spanwinlcel the main cutting edge can be corrected in particular in coiled drills by a Hauptschneidenlcorrektur, or an additional Hauptclxneidenkorrekrurschliff to the desired level, so that the desired cutting wedge stability and

Main cutting edge wear resistance results. Advantageously, the drill is designed so that the Hauptschneidenlcorrelctur can be ground in one go with the Querschneidenausspitzung.

The proposed geometry of the drill tip is particularly suitable for double-edged drills. In addition, however, the use of three-knife or drill with a leading main cutting web and a trailing friction ahlensteg each subdivided by an additional clamping web would be conceivable.

Further developments relate to a Innenlcühlung the drill according to the invention, preferably coiled from the drill webs depending on Ausführungsfonn or just by the Drill through extending cooling channels is formed. The cooling channels can have an elliptical or trigoniform cross-sectional profile, in particular for drills with smaller nominal diameters. It would also be conceivable on the drill axis extending through the drill and in the region of the drill tip Y-shaped spread Innenlaihlkanal conceivable.

The mouth openings are preferably on the open spaces of the webs. Advantageously, the mouth openings are thereby widened by an additional relief grinding to the web back and thus to the flute by a Steigücken to the web Irin steeper than the free surface sloping relief cut to a higher throughput in the direction of saving groove out. With the drills designed in this way, in addition to the use of a coolant emulsion and the

Minimum quantity lubrication (MQL) with an oil-air aerosol is possible to cool the drill bit and to reduce the frictional resistance during machining and chip removal by lubrication.

In the embodiment according to claim 8, however, the cutting insert is an insert, which is screwed on the drill in the circumferential direction. In this case, the entire drill tip with two main cutting edges and secondary cutting elements (-absclmitten) be designed as an insert, which is inserted into a designated receiving groove on the front side of the carrier and screwed or soldered there.

But also indexable inserts, each only one main cutting edge or a

Make Hauptschneidenabsclrnitt and are screwed on corresponding plate seats are conceivable, especially at the stage in a step tool. Incidentally, there could also be provided a corresponding carrier plate equipped with a cutting plate. In this way, it is not only possible to use the inventive cutting geometry-Haitstoff combination with interchangeable inserts and a standard Werlczeugträger, but also can

production technology significantly facilitated: The cutting geometry does not need to be ground directly into the hard material on the drill, but can - at least in sections - are ground on easily accessible hard material inserts. In the following some advantageous embodiments of the inventions will be described with reference to FIGS.

Show it:

Fig. 1 is a schematic side view of a spiral grooved drill according to an embodiment of the invention;

Fig. 2 is a schematic side view of a spiral grooved drill in plan view.

Reference is made to FIG. 1. There is a double-edged drill bit 10. With 1 the main cutting edge is concave 12 and with 8 the main cutting edge of the drill 10 is denoted by 11, with 5 the transverse cutting edge, 2 the tangential course the main sheath to the outer circumference of the drill diameter and with 3 the Nebensclrneide. As can be seen, the main cimeide 1, starting from the center of the drill in radii direction, runs cocavely and merges into a convexly rounded main cutting edge, which continues gently into a secondary cutting edge 3.

The course of the main cutting edge 1 is determined by the Ausspitzung 4, which shortens the transverse cutting edge 5 and interrupts the convex flank profile 7 of the convex main cutting edge 8. The main cutting edge 1 has a concave profile, which has a chip and a clearance angle.

In FIG. 2, the rake angle 6 and the clearance angle 9 of the main cutting edge 1 are shown.

The rake surface 6 has at the Hauptsimeime 1 a steeper angle compared to the adjacent angle of the free surface. 9

Claims

claims

1. hard-material drill with divided by flutes webs and at least two

Main cutting edges (1; 8) having a tangential course to the outer circumference of the drill diameter (2) and a transition to the transverse cutting edge (5), characterized in that

the main cutting edge (1) starting from the transverse cutting edge (5) is at least partially concave 12 in radial direction outwards relative to the outside diameter of the drill bit 10.

2. Hard material drill according to one of the preceding claims, characterized by a shortening of the transverse cutting edge (5) causing Ausspitzung (4).

3. hard-material drill according to one of the preceding claims, characterized in that the convexly curved portion (1 1) of the Hauptsclineide (8) substantially tangentially 2 to the secondary cutting edge (3) connects.

4. hard-material drill according to one of the preceding claims, characterized in that the main cutting edge 1, 8 has a concave 12 and a convex shape 11.

5. hard-material drill according to one of the preceding claims, characterized in that it is grooved spirally.

6. hard-material drill according to one of the preceding claims, characterized by a substantially a 4-Flächenanschliff corresponding Spitzenanschliff.

7. hard-material drill according to one of the preceding claims, characterized in that the convex flank 7 of the main sheath 8 consists of several surfaces

8. hard-material drill according to claim 21, characterized in that at least one main cutting edge (1,8) consists of a cutting plate.