EP3846957A1

EP3846957A1 - Drill

Info

Publication number: EP3846957A1
Application number: EP18765613.7A
Authority: EP
Inventors: Helmut Miller
Original assignee: Mk Tools Service GmbH
Current assignee: Mk Tools Service GmbH
Priority date: 2018-09-04
Filing date: 2018-09-04
Publication date: 2021-07-14
Also published as: WO2020048590A1; CN112243398A; US11883887B2; KR20210045479A; US20210205900A1; KR102581858B1

Abstract

The aim of the invention is to improve a drill (10), in particular a spiral drill, comprising a base (12) which extends substantially longitudinally in an axial direction relative to a drill axis and which has a drill section (24), wherein, in the base (12), a radially inner core region (122) and a radial outer region (124) are provided in the drill section (24), and the drill section (24) has multiple spiral recesses (116) in the outer region (124) and a wall part (114) is arranged between each two spiral recesses (116). This aim is achieved, according to the invention, in that the drill (10) comprises at least four main cutting edges, in particular exactly four main cutting edges, and/or that the drill (10) comprises at least three central cutting sections.

Description

DRILL

The invention relates to a drill, in particular a twist drill. The drill is intended for drilling a borehole into a workpiece. In particular, the drill is a metal drill, that is to say it is provided for drilling a drill hole in a metal workpiece.

The drill comprises a base body, which extends essentially elongated in the axial direction to a drill axis. The base body comprises a drill section, which extends in particular in the axial direction of the drill axis up to a drill tip of the drill. In the case of the base body, a core region lying radially inward to the drill axis and a radial outer region are provided in the drilling section. The drilling section has a plurality of spiral-shaped recesses in the outer region and a wall part is arranged between each two spiral-shaped recesses.

Such drills are known from the prior art.

The problem with these drills is on the one hand to achieve a high feed rate during drilling and to achieve good guidance of the drill and at the same time a high precision of the drill hole to be drilled, for example with regard to its roundness, its diameter tolerance and / or the surface properties of the same , to reach. The present invention is therefore based on the problem of improving a generic drill, in particular with regard to these requirements.

According to the invention, this problem is solved in the case of a drill of the type mentioned at the outset in that the drill, in particular the base body, comprises at least four main cutting edges and / or the drill, in particular the base body, comprises at least three central cutting edge sections. In a particularly advantageous embodiment, it is provided that the drill, in particular the base body, comprises exactly four main cutting edges.

In advantageous embodiments, the drill, in particular the base body, comprises exactly three central cutting sections.

In particularly preferred embodiments, the drill, in particular the base body, comprises at least four central cutting edge sections, in particular exactly four central cutting edge sections.

One of the advantages of the invention is to be seen in the fact that the at least four main cutting edges and / or the at least three central cutting edge sections separate, in particular cut off, smaller chips during drilling, thus reducing the risk of chip jams and the like Guidance of the drill is improved.

Another advantage of the solution according to the invention is that the cutting central cutting sections and / or the at least four main cutting edges can increase the feed during drilling compared to conventional drills.

It is particularly advantageous if the central cutting edge sections replace the otherwise usual cross cutting edge. The transverse cutting edge, which is usually arranged in a center of a conventional drill, merely squeezes the workpiece to be drilled. Due to the friction of the cross-cut on the workpiece, a higher cutting pressure is required and the centering of the drill suffers from this friction. Due to the central cutting edge sections and / or the at least four main cutting edges, which are designed in particular to cut into the center, the drill is designed to cut into its center and so the feed can be increased with a lower cutting pressure and a higher centering accuracy can be achieved. The main cutting edges are essentially the same. Insofar as a feature of a main cutting edge is mentioned below without further specification of the main cutting edge, this is to be understood that at least one main cutting edge comprises this feature, preferably all of the main cutting edges comprise this feature.

The drill extends in the axial direction of the drill axis up to an end face which is arranged at the front of the drill in relation to a feed direction during drilling.

In particular, the main cutting edges run along the end face, in particular exclusively along the end face.

In particular, the drill is rotationally symmetrical with respect to a position and / or a configuration of the main cutting edges with respect to a rotation about the drill axis by 360 ° / l \ l, where N is the number of main cutting edges. Thus, the drill with four main cutting edges is designed to be rotationally symmetrical with respect to a rotation through 90 ° about the drill axis in relation to the position and / or the configuration of the main cutting edges.

In particular, it is provided for the main cutting edges that a respective rake face and a respective free face run towards the main cutting edge and meet at the main cutting edge at a wedge angle. In particular, the wedge angle is at most 110 °, preferably at most 90 °, for example at most 80 °. In particular, the wedge angle is at least 60 °.

The free area runs at a clearance angle to the main cutting edge, the clearance angle being measured between the course of the clearance area and a geometric reference plane running perpendicular to the drill axis. The clearance angle is, for example, at least 1 °, preferably at least 3 °. In particular, the clearance angle is at most 25 °, preferably at most 15 °. The rake face runs towards the main cutting edge at a rake angle, the rake angle being measured between the course of the rake face and a geometrical reference plane which runs parallel to the axial direction of the drill axis and in particular contains the drill axis. For example, the rake angle is between -10 ° and 25 °, with negative values for the rake angle corresponding to a relief-ground main cutting edge.

In one embodiment it is provided that the wedge angle and / or the relief angle and / or the rake angle along at least one main cutting edge is substantially constant along the extent of the main cutting edge.

In a preferred embodiment, however, it is provided that in one, in particular in some, preferably in each of the main cutting edges, the wedge angle and / or the rake angle and / or the clearance angle vary along the extent of the respective main cutting edge, in particular in one of the above mentioned angular ranges vary.

In particular, it is provided that the main cutting edges each comprise different main cutting edge sections, the individual main cutting edge sections each being formed by partial surfaces of the rake surface and the free surface.

It is expedient if at least one main cutting edge, in particular each of the main cutting edges, comprises an outer cutting edge section running in the outer region. The main cutting edge outer sections of the respective main cutting edges are preferably of essentially the same design.

It is preferably provided that at least one main cutting edge outer section, in particular each of the main cutting edge outer sections, runs completely through the outer region in the direction radial to the drill axis. For example, the main cutting edge outer section runs essentially in a straight line through the outer region.

However, it is preferred if the main cutting edge outer section, in particular lightly, runs through the outer region in a curved manner.

It is particularly expedient if at least one main cutting edge, preferably each main cutting edge, in particular its main cutting edge outer section, extends radially inward starting from a radial outside of the base body and in particular runs radially inward through the outside area.

In particular, it is provided that at least one main cutting edge, in particular each main cutting edge, runs at least in sections along a radial extent of one of the wall parts.

The main cutting edge outer section preferably runs completely along the radial extent of one of the wall parts.

In particular, a wall side of the wall part, which delimits a spiral-shaped recess, forms an outer chip surface as a partial surface of the chip surface for the main cutting edge outer section.

In particular, the wall side on which the main cutting edge runs is arranged in front of the corresponding wall part in relation to a direction of rotation when drilling about the drilling axis.

In preferred embodiments, it is provided that the main cutting edge is undercut in the area of the main cutting edge outer section, that is to say the rake angle has a negative value in this area.

It is particularly expedient if at least one main cutting edge, in particular each of the main cutting edges, has at least a partial area of a respective one Wall face forms an outer free area as a partial area of the free area for the main cutting outer portion.

In preferred embodiments it is provided that at least one main cutting edge, in particular each main cutting edge, comprises a main cutting edge core section which runs in the core area.

In particular, the drill comprises a core part in the core area. In particular, the wall parts run along an axial extent of the core part in a spiral around it.

It is particularly expedient if the core part has core recesses in a tip end region, which extends in front of the drill in relation to the feed direction and in particular comprises the end face.

In particular, the core recesses are open towards the end face and radially outward.

In particular, the core recess opens radially outwards at an opening angle. The opening angle is measured in particular between two core wall sides of the core recess, which run essentially radially outwards.

In particular, the opening angle of at least one core recess, in particular each core recess, for a drill with at least four main cutting edges, in particular with exactly four main cutting edges, is at most 55 °, preferably at most 45 °, for example at most 40 °.

For example, the opening angle of at least one core recess, in particular each core recess, is at least 30 ° in a drill with at least four main cutting edges, in particular with exactly four main cutting edges. Preferably, a core recess merges radially outwards into a respective spiral recess.

It is advantageous if at least one of the core recesses forms a taper with one of the spiral recesses.

It is particularly advantageous if each of the core recesses forms a taper with its respective spiral recess for one main cutting edge.

In preferred embodiments, it is provided that at least one main cutting core section, in particular each main cutting core section, runs along a respective core recess of the base body in the core region, that is to say in particular a core recess in the core part.

In particular, a respective core wall part runs between two core recesses essentially in the radial direction.

In particular, each core wall part essentially forms a continuation in the radial direction of the drill axis of a respective wall part in the tip end region.

It is preferably provided that at least one main cutting core section, in particular each main cutting core section, runs along a respective core wall part.

At least one main cutting edge, in particular each main cutting edge, preferably runs continuously through the outer region into the core region.

In particular, it is provided that in at least one main cutting edge, in particular in each main cutting edge, its main cutting edge core section and its main cutting edge outer section merge into one another. In one embodiment it is provided that the main cutting edge has a kink during the transition from the main cutting edge outer section to the main cutting core section.

In a preferred embodiment, however, it is provided that the main cutting edge core section and the main cutting edge outer section flow smoothly into one another, that is to say in particular the main cutting edge has no kink during this transition.

The central cutting edge sections are arranged in a central area of the drill.

In particular, the central area is an area of the core area that is radially inner with respect to the drill axis.

For example, the core recesses extend in the radial direction to the drill axis up to the central area but not into it.

Provision is preferably made for the base body, in particular its core part, to be solid in the central region, that is to say in particular in the central region without any recesses.

Basically, the central sections run on the end face of the drill, in particular exclusively on the end face of the drill.

In preferred embodiments, it is provided that at least one central cutting section, in particular each central cutting section, extends radially inward to the drill axis up to a front tip of the drill. For example, the at least one central section, in particular each of the central sections, runs essentially radially inwards up to the drill axis. The drill thus also has cutting sections in the central region, which in particular replace an otherwise conventional cross cutting edge, as a result of which friction between the drill and the workpiece to be drilled is reduced and feed can be increased.

For example, the front tip is essentially pyramid-shaped, the central cutting edge sections in particular forming the edges of the pyramid shape. This allows the centering of the drill to be improved.

In particular, it is provided that in at least one central cutting section, in particular in each central cutting section, a central free surface of the base body extends at a central clearance angle up to the central cutting section. The central clearance angle is measured between the course of the central clearance surface and a geometric reference plane running perpendicular to the drill axis.

The central clearance angle is preferably at least 3 °.

For example, the central clearance angle is at most 25 °, preferably at most 15 °.

In particular, it is provided that in at least one central cutting section, preferably in each of the central cutting sections, a central cutting surface of the base body extends at a central cutting angle up to the central cutting section. The central rake angle is measured between the course of the central rake surface and a geometric radial reference surface. The geometrical radial reference surface runs parallel to the drill axis and in particular the geometrical radial reference surface contains the drill axis.

In particular, the central rake angle is at least -5 °. The phrase that the angle is at least -5 ° is understood to mean that the angle either has a negative value and its absolute value is less than or equal to 5 ° or that the central rake angle is 0 ° or that the central rake angle has a positive value.

Negative values of the central rake angle correspond to an undercut of the central cutting section in relation to the geometric radial reference surface.

In particularly preferred embodiments it is provided that the central rake angle is at least -1 °, in particular greater than 0 °.

For example, the central rake angle is at most 20 °, in particular at most 15 °.

It is preferably provided that the central cutting edge sections run towards one another in a radially inward direction towards the drill axis.

In particular, it is provided that at least one central cutting edge section, in particular each of the central cutting edge sections, runs towards the drill axis at an angle of increase. The angle of rise between the course of the central cutting edge section and the radial direction of the drill axis is measured.

For example, the angle of rise is at least 5 °, preferably at least 15 °, particularly preferably at least 20 °.

In particular, the rise angle is at most 40 °, for example at most 35 °, preferably at most 30 °.

In particularly preferred embodiments, it is provided that at least one main cutting edge, in particular each of the main cutting edges, comprises a main cutting edge central section. The main cutting central section runs in the central area of the drill. The one main cutting edge or each of the main cutting edges is thus designed to cut into the central region, which improves the removal of the chips and reduces friction of the drill. This enables the drill to be advanced when drilling with greater precision.

In particular, it is provided that at least one main cutting edge, in particular each main cutting edge, has its main cutting edge central section connected to its main cutting edge core section and / or to its main cutting edge outer section. This has the advantage that the main cutting edge runs continuously radially inwards to the central area and so the chips are effectively removed during drilling.

In particularly preferred embodiments, at least one of the main cutting edges, in particular each of the main cutting edges, runs continuously from the outside of the drill, in particular of the base body, radially inward into the central region and, for example, essentially up to the drill axis.

In particular, it is provided that with a main cutting edge, preferably with each of the main cutting edges, its main cutting edge central section merges into its main cutting edge core section. The main cutting edge is thus designed to cut continuously in a radially outer edge region of the central region.

In some preferred embodiments, the main cutting center section merges smoothly, that is, without a kink, into the main cutting core section.

In other preferred embodiments, the main cutting edge has a kink during the transition from its main cutting edge central section into its main cutting core section. It is particularly expedient if at least one main cutting edge central section, in particular each of the main cutting edge central sections, is formed by a central cutting edge section with one or more of the features mentioned above.

In some preferred embodiments, each of the central cutting edge sections forms a main cutting edge central section. In this embodiment, the drill thus includes as many central cutting sections as main cutting edges. In particularly preferred embodiments, the drill comprises four main cutting edges and four central cutting edge sections, the four central cutting edge sections forming the four main cutting edge central sections.

In other preferred embodiments, the drill includes more

Central cutting sections as main cutting edges.

For example, between each two central cutting edge sections, which also form a main cutting edge central section of one of the main cutting edges, a central cutting edge section is arranged, which is not assigned to any main cutting edge.

In a particularly preferred embodiment, the drill comprises two main cutting edges and four central cutting edge sections, two of the central cutting edge sections each forming a main cutting edge central section. It is preferably provided that, with respect to the direction of rotation around the drill axis, a central cutting section, which does not form a main cutting central section, is arranged between the two central sections forming a main cutting central section.

In preferred embodiments it is provided that at least one wall part, in particular each wall part, has an auxiliary cutting edge. This in particular improves the precision when drilling. In particular, it is provided that the at least one minor cutting edge or each of the minor cutting edges runs on the outside of the respective wall part.

In particular, the one minor cutting edge or the multiple minor cutting edges run essentially along the spiral shape of the respective wall part.

For example, it is provided that at least 15%, preferably at least 25%, particularly preferably at least 30%, for example at least 35%, of a radius of the base body in the drilling section runs through the core region. This provides a drill which is more stable than previously because of the thicker core.

For example, at most 45%, in particular at most 40%, the radius of the base body in the drilling section runs through the core area.

In particular, at least 15%, preferably at least 25%, for example at least 30%, of a radius of the core area runs through the central area of the core area.

In particular, it is provided that the radius of the core area runs through the central area of the core area to a maximum of 50%, in particular to a maximum of 40%.

In particular, at least one of the spiral recesses, in particular each of the spiral recesses, in a drill with at least four main cutting edges, in particular with exactly four main cutting edges, runs in a cross-sectional area running perpendicular to the drill axis through an angular range which delimits the spiral recess Wall sides is limited, which has an opening angle of at least 40 ° and / or an opening angle of at most 60 °. In particular, it is provided that at least one of the wall parts, in particular each wall part, for a drill with at least four main cutting edges, in particular with exactly four main cutting edges, runs through an angular range in a cross-sectional area perpendicular to the drill axis, the angular range having an opening angle of has at least 30 ° and / or an opening angle of at most 50 °.

In particularly preferred embodiments, the base body is coated at least in the drilling section and / or, for example, in the fastening section, in particular with a layer hardening the base body. This makes the base body more stable and longer tool life is possible.

In particular, it is provided that the base body tapers in the area of the drilling section against the feed direction.

In particular, it is provided that the base body has a fastening section.

In particular, the fastening section extends in the direction axial to the drill axis, in particular starting from a rear side opposite the end face. For example, the fastening section extends essentially up to the drill section.

The fastening section is provided in particular for insertion into a drilling machine. The drill can thus be fastened to the fastening section on the drilling machine and the drilling machine can transmit a rotational movement about the drilling axis to the drill for drilling.

In particularly preferred embodiments, it is provided that the base body has a larger radius in the region of the fastening section than in the drilling section. This allows the drill, in particular, to be more firmly attached to the drilling machine due to the larger area on the fastening section fasten and a higher torque can be transferred to the drill and the feed during drilling can be increased.

It is particularly preferred if the drill has a cooling device with one cooling channel or with several cooling channels.

A cooling liquid can be transported to the borehole through the one cooling channel or the multiple cooling channels. The drill is cooled by the coolant, which means that the feed can be increased.

In a preferred embodiment it is provided that at least one cooling duct runs through one of the wall parts at least in sections. For example, a cooling channel runs through at least two of the wall parts, in particular through each of the wall parts, at least in sections.

In particular, it is provided that at least through a wall part

cooling channel running in sections at the end of the drill with an opening emerging from the wall part. The coolant is thus transported directly to the drill tip and the main cutting edges are cooled directly.

For example, the cooling liquid emerging at the tip of the drill is pressed back through the spiral-shaped recesses against the feed direction, so that the chips are also better transported away.

In a particularly preferred embodiment, it is provided that at least one cooling duct, in particular each of the cooling ducts running through a wall part, runs at least approximately along the entire spiral extension of a wall part. It is thereby achieved that the opening of the cooling channel is in each case arranged on the wall end face of the wall part even when the drill is reground. In another advantageous embodiment, it is provided that the cooling duct running through the wall part extends radially inward to a central duct. This enables a structurally simple solution.

In a further preferred embodiment it is provided that at least one cooling duct, for example as a groove, runs on an outside of the fastening section. This enables the drill to be provided with at least one cooling channel in a structurally simple manner.

Further advantages and preferred features of the drill are the subject of the following description and the drawing of some exemplary embodiments.

The drawing shows:

Figure 1 is a side view of a drill with four main cutting edges according to a first embodiment;

Figure 2 is a perspective view of the drill according to the first

Embodiment;

Figure 3 is a perspective view of a view of an end face of the

Drill of the first embodiment;

Figure 4 is a perspective view of a drill tip of the drill of the first embodiment;

Figure 5 is a perspective view from one side of the drill tip of the drill according to the first embodiment;

FIG. 6: a top view of the drill tip of the drill of the first exemplary embodiment; FIG. 7: a detail enlarged representation of the representation according to FIG. 6;

FIG. 8 shows a perspective illustration of a front tip with central cutting edge sections of the drill of the first exemplary embodiment, the front tip being cut along a cutting surface which is essentially perpendicular to a central cutting edge section;

FIG. 9: the section according to FIG. 8 with the angles shown;

Figure 10: a representation similar to Figure 8, with the section through two

Central cutting sections runs;

Figure 11: a perspective enlarged in the area of a main cutting edge

Representation of the drill tip of the drill of the first exemplary embodiment;

FIG. 12: a plan view similar to FIG. 6 of a drill tip of a drill with two main cutting edges and four central cutting edge sections according to a second exemplary embodiment;

FIG. 13: an enlarged representation of FIG. 12;

FIG. 14: a top view similar to FIG. 6 of a drill tip of a drill with cooling channels in the wall parts according to a third exemplary embodiment;

Figure 15: a section axially to the drill axis through a

Variant of the drill according to the third embodiment; FIG. 16: a schematic side view of a drill with grooves in a fastening section of the same according to a fourth exemplary embodiment; and

Figure 17: a schematic perpendicular to the drill axis

Cross section through the fastening portion of the drill of the fourth embodiment.

In a first exemplary embodiment of a drill designated as a whole by 10, which is shown by way of example in FIGS. 1 to 11, it comprises a base body 12 which extends essentially elongated in the axial direction of a drill axis 14.

In the following, information on the orientation, orientation, position and the like, which relate to an axis, such as “axial”, “radial”, are to be understood with respect to the drill axis 14, unless a different specification is specified .

In particular, the base body 12 extends at least in sections essentially cylindrical in the axial direction.

The drill axis 14 extends in the axial direction essentially in the direction of a feed direction 16, the drill 10 being moved into a workpiece to be drilled in the direction of the oriented feed direction 16 during drilling.

The drill axis 14 essentially corresponds to an axis of rotation about which the drill 10 rotates in a direction of rotation 18 during drilling.

In particular, the base body 12 comprises different sections and parts, as described below, but is formed in one piece. The base body 12 comprises a fastening section 22 and a drilling section 24. The fastening section 22 is provided in particular for fastening the drill 10 to a drilling machine, and the drilling section 24 in particular comprises a cutting part 26 of the drill 10 and is for drilling in a workpiece to be drilled, in particular a metallic workpiece.

The fastening section 22 and the drilling section 24 are axial sections of the base body 12 which extend longitudinally along the drill axis 14. In particular, a transition region 28 of the base body 12 is provided, in which the drilling section 24 merges into the fastening section 22.

In particular, the fastening section 22 extends from a rear side 52 of the base body 12 in the axial direction into the transition region 28.

The fastening section 22 has an outer side 54 which, in this exemplary embodiment, extends essentially coaxially to the drill axis 14.

The outer side 54 runs essentially at a radius 56 from the drill axis 14 around it, and in this exemplary embodiment the radius 56 is approximately constant along the axial extent of the fastening section 22.

In particular, in this exemplary embodiment, the fastening section 22 is essentially designed as a cylindrical shaft.

In variants of the exemplary embodiment, the fastening section 22 is essentially designed as a taper shaft.

The drilling section 24 extends longitudinally axially to the drill axis 14 and in the direction of the feed direction 16 up to an end face 72 of the base body 12. In particular, the drilling section 24 extends from the end face 72 to the transition region 28.

The end face 72 is an end side of the base body 12 in the axial direction.

In the case of functional drilling, the end face 72 is a front of the base body 12 in relation to the feed direction 16 and penetrates as the first part of the base body 12 into the workpiece to be drilled.

On the end face 72, the drilling section 24 forms a drill tip 76 in a tip end region 74, which is followed by a main drilling section 78 along the further axial extent of the drilling section 24.

The main drilling section 78 extends axially between the tip end area 74 and a connecting end area 82 of the drilling section 84, at which the drilling section 24 merges into the next axial section of the base body 12, in particular into the fastening section 22 in the transition area 28.

The drilling section 24 has a radius 86, which is measured in particular in the main drilling section 78.

The radius 56 of the fastening section 22 is preferably larger than the radius 86 of the drilling section 24. Thus, a radius of the base body 12 increases, for example in the transition region 28.

For example, a step 92 is provided in the transition area 28.

In the drilling section 24, the drill 10 has a core part 112 and four wall parts 1141, 114II, 114III, 114IV, collectively referred to as the wall parts 114, and four spiral recesses 1161, 11611, 116III, 116IV, collectively referred to as the spiral recesses 116 ( Fig. 2, 3). In the following, elements that are essentially of the same design and perform at least the fundamentally the same function are jointly described and given a common reference symbol, for example the wall parts 114 and the spiral-shaped recesses 116 fulfilling elements are to be referred to or exactly such an element is to be described, a Roman numeral identifying this exactly one element is appended to the common reference sign

The core part 112 and the wall parts 114 are parts of the one-piece base body 12 and the spiral-shaped recesses 116 are recesses in this base body 12.

The core part 112 extends coaxially to the drill axis 14 essentially along the entire axial extent of the drill section 24, specifically in a core region 122 thereof.

The three-dimensional core area 122 runs coaxially to the drill axis 14. In particular, the core area 122 is rotationally symmetrical to the drill axis 14 and, for example, cylindrical with a circular base. The base body 12 is essentially solid in the core region 122 and forms the core part 112.

An outer region 124 runs in a circumferential direction around the drill axis 14 radially outside the core region 122 around it, and in the axial direction the outer region 124 runs essentially coaxially to the drill axis 14 and the core region 122.

In particular, the core area 122 with a radial outside touches the outside area 124 on a radial inside of the outside area 124. For example, the core area 122 and the outside area 124 touch at a radial distance from the drill axis 14 corresponding to a core radius 126.

The wall parts 114 are arranged in the outer region 124.

The wall parts 114 are connected to the core part 112 and in a transition from the outer region 124 to the core region 122, the wall parts 114 merge into the core part 112.

The radius 86 of the drilling section 24 corresponds in particular to a radial distance of an outer side 132 of a wall part 114 from the drill axis 14.

The wall parts 114 run along the axial extent of the core part 112 in the main drilling section 78 in the outer region 124 in a spiral around the core part 112 up to at least partially into the tip end region 74.

For example, a spiral angle of the wall parts lies in the range between 10 ° and 60 °, the spiral angle indicating the slope of a spiral shape of the spiral-shaped recesses 116.

The wall parts 114 end on the end face 72 and form wall end faces 136 at their end there.

The wall end faces 136 run in the tip end region 74. In particular, the wall end faces 136, starting from the outside 132, increase slightly in the direction of the feed direction 16 with increasing radial inward extension.

The wall parts 114 each form two wall sides 138 along their spiral course. On the one hand, the wall sides 138 run radially inward from the outer side 132 and on the other hand run along the spiral

Extension of the respective wall part 138.

A wall part 114 is arranged in each case between two spiral-shaped recesses 116, for example the wall part 1141 is arranged between the spiral-shaped recesses 116IV and 1161.

The spiral recesses 116 run in the outer region 124 and correspond to the spiral course of the wall parts 114. In particular, the spiral recesses 116 extend radially to the core region 122, but not into the core region 122.

In particular, at least a small area of the core part 112 thus delimits the spiral-shaped recesses 116 in the radial direction. Otherwise, the wall parts 114 limit the spiral-shaped recesses 116 with their wall sides 138, two wall parts 114 in each case essentially in the circumferential direction around the drill axis 14 each delimit a spiral recess 116. For example, the spiral recess 11611 is delimited by the wall parts 11411 and 114III.

The spiral-shaped recesses 116 are open radially outward.

In particular, a wall part 114 and a spiral-shaped recess 116 each run through a cross-sectional area perpendicular to the drill axis 14 in each of a quadrant emanating from the drill axis 14.

For example, through the cross-sectional area running perpendicular to the drill axis 14, the wall part 114 runs through an angular region 139 starting from the drill axis, which is for example between 40 ° and 60 ° in size. In particular, through the cross-sectional area running perpendicular to the drill axis 14, the spiral recess 116 runs through an angular region 141 starting from the drill axis 14, which is, for example, between 30 ° and 50 ° in size.

The angular ranges 139 and 141 relate in particular to the extent of the wall part 114 or the spiral recess 116 along the outside of the base body 12 in the circumferential direction around the drill axis 14.

The spiral recesses 116 form flutes through which chips generated during drilling can or can be removed from the drill tip 76.

It is preferably provided that the wall parts 114 each have a guide chamfer 142 on their respective outer side 132, the respective guide chamfer 142 preferably being arranged in an end section of the outer side 132 starting from the tip end region 74.

In variants of the exemplary embodiment, it is provided that the wall parts 114 each have an auxiliary cutting edge 144.

In particular, the secondary cutting edge 144 runs essentially in a spiral shape at least along a section of the spiral extension of the wall part 114.

In particular, the secondary cutting edge 144 runs on the outer side 132, specifically at an end of the outer side 132 which runs along a spiral recess 116 and which is at the front with respect to the direction of rotation.

In particular, it is provided that the drilling section 24 tapers in the direction opposite to the feed direction 16, that is to say in particular from the tip end area 74 to the connecting end area 82. For example a taper in the range of 0.1 mm to 1 mm to 100 mm axial extent is provided, in particular a taper of at least approximately 0.5 mm to 100 mm axial extent.

In this exemplary embodiment, four core wall parts 1521, 15211, 152III and 152IV are provided in the tip end region 74. The core wall parts 152 extend in the core area 122 (FIGS. 3 and 4).

In particular, a core wall part 152 forms a preferably continuous continuation of a respective wall part 114 into the core area 122.

In particular, the core wall parts 152 are formed from the core part 112.

The core wall parts 152 end on the end face 72 and form respective core wall end faces 154. The core wall end faces 54 extend with increasing radial inward extension, in particular in the direction of the advancing direction.

The core part 112 has four core recesses 1561, 156II, 156III, 156IV in the tip end region 74. The core recesses 156 in particular do not extend into the main drilling section 78 in the axial direction.

A core wall part 152 runs between two core recesses 156 adjacent in the circumferential direction about the drill axis 14. The core wall part 152 essentially runs in the radial direction to the drill axis 14 and, with respect to its radial extent, delimits a core recess 156 with one each on each side Core wall side 158.

For example, the core wall part 1521 is arranged between the core recesses 156IV and 1561 in relation to the direction of rotation around the drill axis 14. The core wall part 1521 extends between the two core recesses 156IV and 1561, in particular starting from the wall Part 1141 radially inward into the core region 122 and, on the one hand, partially delimits the core recess 156IV and the core recess 1561 with its sides relating to this radial extent.

The core recesses 156 are open towards the end face, that is to say in the direction of the feed direction 16, and are delimited in the circumferential direction around the drill axis 14 by a core wall part 152 in each case.

In the direction radial to the drill axis 14, the core recesses 156 merge into a corresponding spiral recess 116. For example, the core recess 1561 merges radially outward into the spiral recess 1161.

In particular, the respective core wall sides 158 merge into a corresponding wall side 118 and in particular into a tapering surface 160 thereof, which runs between the wall end face 54 and a wall surface of the wall side 118 which delimits the spiral-shaped recess 116 and extends correspondingly to this.

The core recesses 156 each extend in the radial direction, in particular starting from the respective spiral recess 116, up to a respective core recess end region 162 into the core part 112.

In particular, the core recesses 156 taper with increasing radial inward extension starting from the respective spiral recess 116. The two core wall sides 158 delimiting the corresponding core recess 156 run towards one another with increasing radial inward extension and meet in the core recess end region 162. In particular, the two core wall sides 158 essentially run towards one another at an opening angle 159. For example, the opening angle 159 is at least approximately 35 °.

In particular, the core recesses 156 and the spiral recesses 116 form, for example through the tapering surface 160, in

Tip end area 74 each taper for the drill tip 76.

The core part 112 has a central section 162 which extends in a central region 166.

The central region 166 runs centrally in the core region 122 with respect to the radial direction to the drill axis 14.

In particular, the central region 166 is a radially innermost region of the core region 122.

In particular, the central region 166 in the core region 122 runs coaxially to the latter and to the drill axis 14.

The central section 162 is the section of the core part 112 lying radially inward of the drill axis 14.

The drill axis 14 runs through the central section 162 and this runs essentially coaxially to the latter.

The central section 162 is solid in particular in the tip end region 74, for example free of recesses.

The central section 162 extends axially to the end face 72 and forms a front front section 172 there. In relation to the feed direction 16, the central section 162 thus forms the most forwardly arranged section of the drill 10 and in particular the drill tip 76. In particular, the central section 162 is formed in the front section 172 as a front tip 176.

A front end of the front section 172 with respect to the feed direction 16, in particular the front tip 176, is formed by front surfaces 178 of the central section 162.

In particular, the front tip 176 is essentially pyramid-shaped, the front surfaces 178 essentially forming the lateral surfaces of the pyramid-shaped front tip 176. It is particularly expedient if the front surfaces have grinding as described below.

The front surfaces 178 preferably run towards one another at the drill axis 14.

In particular, it is provided that the front surfaces 178 merge with their radially extending extent at a radial outer edge of the central region 166 into a respective core wall end face 154, in particular continuously. For example, the front surface 178II merges into the core wall end surface 15411.

In this exemplary embodiment, the drill 10 comprises four central cutting edge sections 2101, 210II, 210III, 210IV (FIGS. 5-10).

The central cutting edge sections 210 run in the central region 166, in particular up to the front tip 176.

In particular, the central cutting edge sections 210 essentially extend outward from the drill axis 14 at least approximately in the radial direction, for example to the edge of the central region 166. In particular, the central cutting edge sections 210 do not extend beyond the central region 166.

In particular, the central cutting edge sections 210 run towards the drill axis 14 at least approximately at the same angle to adjacent central cutting edge sections 210.

In particular, the central cutting edge sections 210 extend radially inward toward the drill axis 14 and run along this radial extension obliquely to the radial direction of the drill axis 14, the course of the central cutting edge sections 210 including an angle of increase A with the radial direction (FIG. 9).

The central cutting edge sections 210 are each formed by a central cutting surface 212 and a central free surface 214. The central chipping surface 212 and the central free surface 214 meet at the central cutting section 210 at a central wedge angle ZK.

The central chip surface 212 is arranged in relation to a rotation of the drill 10 about the drill axis 14 in the direction of rotation 18 in front of the central free surface 214.

The central wedge angle ZK and the meeting of the central cutting surface 212 and the central free surface 214 are designed such that the respective central cutting edge section 210 is designed to be cutting.

The central free surface 214 runs at a central free angle ZF toward the central cutting section 210, the central free angle ZF being measured between the course of the central free surface 214 and a geometric reference surface running perpendicular to the drill axis 14 (FIG. 9). In particular, the central clearance angle ZF is between 1 ° and 20 °. The central rake surface 212 runs at a central rake angle ZS toward the central cutting section 210, the central rake angle ZS being measured between the course of the central rake surface 212 and a geometric radial reference surface. The geometric radial reference surface extends from the drill axis 14 in its radial direction, so that the radial reference surface is spanned by the axial direction and a radial direction to the drill axis 14 and contains the drill axis 14.

In particular, the central rake angle ZS is between -5 ° and 25 °. In this case, negative values of the central rake angle correspond to a undercut central cutting section 210, so that an undercut occurs in the area of the central rake surface 212.

In particular, if the central cutting section 210 is undercut, it is provided to provide a central rake angle with an absolute value between 0 ° and 5 ° or to provide a central cut section 210 which is not undercut, in which case the central rake angle ZS, for example, has an absolute value between 0 ° and 20 ° .

The central chipping surfaces 212 and the central free surfaces 214 are in particular formed by the front surfaces 178 of the central section 162, in particular ground out.

A front surface 178 extends between two central cutting edge sections 210 and forms the central cutting surface 212 for one central cutting edge section 210 and the central free surface 214 for the other central cutting edge section 210 on the other side. For example, the front surface 178II, which runs between the central cutting edge sections 2101 and 210II and in particular merges into the core wall end face 15411, forms the central cutting surface 2101 on the side of the central cutting edge section 2101 and the central free surface 21411 on the side of the central cutting edge section 210II (FIG. 10). . The front surfaces 178 are thus designed to be slightly curved so as to converge on the corresponding sides under the corresponding central clearance angle or central rake angle on the respective central cutting edge section 210.

In this exemplary embodiment, the drill 10 has four main cutting edges 3001, 300II, 300III, 300IV at the drill tip 76 (FIGS. 5-11).

The main cutting edges 300 run, in particular exclusively, on the end face 72 of the drill 10.

In particular, the main cutting edges 300 have individual sections, specifically in this exemplary embodiment the main cutting edges 300 each comprise a main cutting edge outer section 302, a main cutting edge core section 304 and a main cutting edge central section 306.

The main cutting edges 300 are each formed by a rake face 312 and a free face 314 meeting. In particular, the rake surfaces 312 and the free surfaces 314 each have individual partial surfaces, which will be explained in more detail below.

The rake face 312 and the free face 314 of a respective main cutting edge 300 meet at a wedge angle K on the main cutting edge 300 and thus form the cutting edge of the main cutting edge 300.

In particular, it is provided that the wedge angle K varies along the extent of the main cutting edge 300.

The rake face 312 runs towards the main cutting edge 300 at a rake angle S. The rake angle S is measured between the course of the rake face 312 and a corresponding geometric radial reference plane, which runs parallel to the drill axis 14, for example includes it. For example, the rake angle S is in a range between -5 ° and 20 °, where negative angles of the rake angle S correspond to a relief-ground main cutting edge 300.

In particular, it is provided that the rake angle S varies along the extent of the main cutting edge 300.

The free area 314 runs at a clearance angle F towards the main cutting edge 300. The clearance angle F is measured between the course of the clearance surface 314 in a corresponding geometric reference plane, which runs perpendicular to the drill axis 14. For example, the clearance angle F is in the range between 1 ° and 20 °. In particular, it is provided that the clearance angle F varies along the extent of the main cutting edge 300.

The wedge angle K, the rake angle S and the clearance angle F are generally defined angles for cutting edges and are not shown in the drawing.

The main cutting edge outer section 302 runs through the outer region 124 and preferably completely through it.

The main cutting edge outer section 302 extends along a corresponding wall part 114. For example, the main cutting edge outer section 3021 of the main cutting edge 3001 extends along the wall part 1141.

The main cutting edge outer section 302 runs along an edge of the wall part 114, which is formed by the wall end face 136 and the wall side 118, in particular the surface thereof. The wall side 118 of the wall part 114, which also forms the main cutting edge outer section 302, is that wall side 118 of the wall part 114 which is arranged at the front of the wall part 114 in relation to the direction of rotation 18. In particular, the main cutting edge outer section 302 extends radially inward through the outer region 124 from the outer side 132 of the wall part 114.

The surface of the wall side 118 forms an outer chip surface 322 as a partial surface of the chip surface 312 for the main cutting edge outer section 302.

The wall end face 136 forms an outer free area 324 as a partial area of the free area 314 for the main cutting edge outer section 302.

It is preferably provided that the main cutting edge outer section 302 is ground, that is to say the rake angle S has a negative value in the region of the main cutting edge outer section 302.

The main cutting core section 304 runs through the core region 122 and in particular runs completely through it.

In particular, the main cutting edge core section 304 adjoins the main cutting edge outer section 302, and so the main cutting edge 300 runs continuously from the outer region 124 into the core region 122.

The main cutting core section 304 runs along the extent of a corresponding core wall part 152. For example, the main cutting core section 3041 of the main cutting edge 3001 runs along the core wall part 1521.

The main cutting core portion 304 is formed on an edge of the core wall part 152. The edge is formed by the intersecting core wall end face 154 and the surface of the core wall side 158. The core wall side 158 of the core wall part 152, which forms the main cutting core section 304, is that core wall side 158 which is arranged on the core wall part 152 in relation to the direction of rotation 18. The surface of the core wall side 158 forms a core chip surface 342 as a partial surface of the chip surface 312 for the main cutting core section 304.

The core cutting surface 342 runs at a core cutting angle KS to the main cutting core section 304. In this exemplary embodiment, it is provided that the main cutting core section 304 is not undercut and thus the core cutting angle KS has a positive value. In a variant of the exemplary embodiment, however, it is provided that at least partially the main cutting edge 300 is undercut in the region of the main cutting core section 304 and the core cutting angle KS therefore has a negative value at least in sections.

When grinding out the core chip surface 342, it can be helpful to grind into an axial bottom of the corresponding core recess 156, so that a pocket 352 is formed there. The core recess 156 in the pocket 352 has an axial incision, on one side of which the core chip surface 342 extends. On the other side of the pocket 352, its surface rises slightly in the axial direction and then merges into the core wall side 158, which otherwise extends essentially smoothly.

By grinding out the pocket 352, it can be achieved that the main cutting edge 300 runs continuously at the transition between the wall part 114 and the core wall part 152 without a kink.

The main cutting edge core section 304 extends in particular radially inward in the core area 122 and up to the central area 166 and preferably merges there into the main cutting edge central section 306.

The main cutting central section 306 runs in the central region 166. In particular, the main cutting central section 306 runs radially through the Central area 166 through to the front tip 176 and thus essentially to the drill axis 14.

In this case, partial areas of the front surfaces 178 for the respective main cutting edge central sections 306 form a respective main cutting edge central cutting surface 362 as a partial surface of the cutting surface 312 for the main cutting edge 300 in the central area 166.

In addition, partial areas of the front surfaces 178 for the respective main cutting edge central sections 306 form a respective main cutting edge central free area 364 as partial area of the free area 314 for the main cutting edge 300 in the central area 166.

The respective main cutting edge central cutting surface 362 runs at a central cutting angle ZS to the main cutting edge central section 306.

The main cutting edge central free area 364 runs at a central clearance angle ZF to the main cutting edge central section 306.

In this embodiment, the main cutting edge central portions 306 are formed by the central cutting edge portions 210. For example, the central cutting edge section 2101 corresponds to the main cutting edge central section 3061.

The central cutting surface 212 of the central cutting section 210 corresponds to the main cutting central cutting surface 362 of the main cutting central section 306 and the central free surface 214 of the central cutting section 210 corresponds to the main cutting central free surface 364 of the main cutting central section 306. The respective central cutting angles and central free angles also correspond to one another.

In order to avoid repetitions, the description of the main cutting edge central sections 306 is accordingly based entirely on the Explanations in connection with the central cutting edge sections 210 referenced.

In a second exemplary embodiment of a drill 10a, shown by way of example in FIGS. 12 and 13, those elements and features which fulfill the function which is at least fundamentally the same and / or are essentially of the same design as corresponding elements and features in the first exemplary embodiment, are used provided with the same reference numerals and with regard to the description thereof, reference is made in full to the explanations in connection with the first exemplary embodiment. Insofar as alternative configurations of elements or features with at least the fundamentally the same function and / or which are configured essentially the same are described, the same reference number is followed by a letter "a" characterizing the alternative configuration and, to the extent that those elements and features follow not described in more detail, reference is made to the explanations in connection with the first exemplary embodiment with regard to the description thereof.

In contrast to the first exemplary embodiment, the drill 10a of the second exemplary embodiment has two main cutting edges 3001a and 30011a.

Correspondingly, the drill 10a comprises two wall parts 1141a and 11411a and two spiral recesses 1161a and 11611a, which form corresponding flutes.

The wall parts 114a are correspondingly thicker in the circumferential direction around the drill axis 14 than the wall parts 114 of the first exemplary embodiment.

The spiral-shaped recesses 116a in FIG

The circumferential direction around the drill axis 14 is further developed than the spiral-shaped recesses 116 of the first exemplary embodiment. The spiral recesses 116a and the wall parts 114a also run spirally in an outer region 124 around a core part 112a which is arranged in a core region 122.

In contrast, the drill 10a also has only two core recesses 1561a and 15611a, which are arranged between two core wall parts 1521a and 15211a and are delimited by them.

The respective core recesses 156a open radially outwards in accordance with the corresponding spiral recesses 116a.

The core wall parts 152a merge with the wall parts 114a with their radial extension outwards.

In addition, the drill 10a comprises a central section 162a in a central region 166.

As in the first exemplary embodiment, the drill 10a has four central cutting edge sections 2101, 210II, 210III, 210IV and in particular a front tip 156 in the front section 172 of the central section 162a.

Four front surfaces 1781, 178II, 178III, 178IV also correspondingly run between the central cutting edge sections 210 and, as in the first exemplary embodiment, form central cutting surfaces 212 and central free surfaces 214 for the central cutting edge sections 210.

In contrast to the first exemplary embodiment, only two front surfaces 178, for example the front surfaces 1781 and 178III, in particular flowing, merge into a respective core wall end surface 154, for example into the core wall end surface 1541 or 154III. The two other front surfaces 178, for example the front surfaces 178II and 178IV, adjoin a respective cutout surface 160 and in particular an intermediate surface 392, an edge in particular being provided at the boundary thereof. The intermediate surface 392 runs radially outward from the transition from the central region 166 into the core region 122 to the outer region 124, in particular through it to the outer side 132 and between the respective core wall end face 154 and wall end face 136 on the one hand and the cutout surface 160 on the other hand.

In one variant, two front surfaces 178 each merge into a core wall end surface 154. For example, the front surfaces 1781 and 178IV merge into the core wall end surface 1541a.

In particular, the two main cutting edges 300a also have different sections, in particular a main cutting edge outer section 302a, a main cutting edge core section 304a and a main cutting edge central section 306a.

In particular, the two main cutting edge central sections 3061a and 30611a are each formed by a central cutting edge section 210. In this embodiment, the main cutting edge central portion 3061a is formed by the central cutting edge portion 2101 and the main cutting edge central portion 30611a is formed by the central cutting edge portion 210III.

However, the two other central cutting edge sections 210II and 210IV do not form a main cutting edge central section 306.

The two central cutting edge sections 210, which form a main cutting edge central section 306, for example the central cutting edge sections 2101 and 210III, are each arranged between the two central cutting edge sections 210 which do not form a main cutting edge central section 306, that is to say for example the central cutting edge section 210II and 210IV. Thus, in the circumferential direction around the drill axis 14, a central cutting edge section 210 forming a main cutting edge central section 306 and a central cutting edge section 210 which does not form a main cutting edge central section 306 are alternately arranged one behind the other.

In particular, this drill 10a is essentially rotationally symmetrical with two main cutting edges 300a with respect to rotations through 180 ° about the drill axis 14, the formation in the central region 166 with the four central cutting edge sections 210 also being rotationally symmetrical with respect to rotations through 90 ° around the drill axis 14.

In particular, the central section 162 with the front tip 176 in the second exemplary embodiment is essentially rotationally symmetrical with respect to rotations through 90 ° about the drill axis 14.

Otherwise, all other features and elements are at least fundamentally the same as in the first exemplary embodiment, so that reference is made in full to the explanations in connection with this exemplary embodiment.

In a third and fourth exemplary embodiment and their variants, which are shown by way of example in FIGS. 14 to 17, those elements and features which fulfill at least fundamentally the same functions or are at least substantially the same as in the first or second exemplary embodiment are the same Reference numerals are provided as in the preceding exemplary embodiments and reference is made in full to the above statements in connection with these exemplary embodiments with regard to the description thereof. In alternative configurations, a letter characterizing the exemplary embodiment is appended to the same reference symbol.

In a drill 10c of the third exemplary embodiment, channels 412 are provided in the wall parts 114c. In particular, a channel 412 is provided in each of the wall parts 114c.

In variants of the exemplary embodiment, a channel 412 is provided only in some of the wall parts 114c.

For example, channels 412 are arranged in two of four wall parts 114c, a wall part 114c with a channel 412 and a wall part 114c without channel 412 being arranged alternately one behind the other, in particular with respect to the direction of rotation about the drill axis 14.

Even if in the drawing the drill 10c is shown with four wall parts 114c and four main cutting edges 300, the description applies to drills with a different number of wall parts and main cutting edges, for example with three wall parts 114c and three main cutting edges 300 or with two Wall parts 114c and two main cutting edges 300 accordingly.

On the end face 72, the wall part 114c, in particular on the wall end face 136, has an opening 416 of the channel 412.

Starting from the opening 416, the channel 412 runs through the wall part 114c at least in an area that is forward in the feed direction 16.

For example, the channel 412 runs radially inward in the direction of the drill axis 14 and opens there with the further channels 412 into a central channel 422.

The central channel 422 runs axially through the drilling section 24c, in particular up to the fastening section 22.

In particular, the central channel 422 extends only in the main drilling section 78c, so that the central section 162c in the tip end region 74 is also solid in the radially inward region around the drill axis 14. In particular, the main drilling section 78c is also solid except for the central channel 422, and in particular the spiral recesses 116 also only extend in the outer region 124.

The central channel 422 extends further through the base body 12c to a further opening, which is not shown in the drawing.

In a variant of the exemplary embodiment, the channel 412, like the wall part 114c, follows its spiral extension. Thus, in this variant, the channel 412 runs through the wall part 114c along its spiral extension. For example, in this variant, the channels 412 connect into a central channel 422 in the fastening section 22 or in the transition region between the fastening section 22 and the drilling section 24c.

The channels 412 and in particular also the central channel 422 are in particular part of a cooling device 432 for the drill 10c.

For example, a cooling and / or lubricating liquid can be introduced into the central channel 422 via the opening (not shown in the drawing) and into the channel 412 via this or, in the case of variants, directly into the channel 412. The cooling and / or lubricating liquid emerges from the opening 416 on the end face 72 and cools the drill 10c and the workpiece to be drilled.

In a fourth exemplary embodiment of a drill 10d, grooves 452 are provided on the outer side 54d of the fastening section 22d.

In particular, the grooves 452 extend in the axial direction to the drill axis 14 along the outer side 54d of the fastening section 22d.

In particular, the grooves 452 extend to an end of the fastening section 22d that is at the front in relation to the feed direction 16, for example up to the transition region 28. In particular, the grooves 452 open in the axial direction towards the drilling section 24.

In this exemplary embodiment, the grooves 452 are provided as part of a cooling device 432.

A coolant and / or lubricant can be guided through the grooves 452 and brought to the point to be drilled on the workpiece to be drilled.

Otherwise, in the third and fourth exemplary embodiments, the remaining features and elements are at least substantially the same as those in the first and / or second exemplary embodiments, so that with regard to FIG

Full description of the same reference is made to the above statements in connection with these embodiments.

Claims

PATENT CLAIMS

1. Drill (10), in particular twist drill, comprising one in

Main body (12), which extends substantially elongated in the axial direction of a drill axis (14), which comprises a drilling section (24), with a core region (122) radially inward of the drill axis (14) in the drilling section (24) in the main body (12) ) and a radial outer region (124) are provided and the drilling section (24) in the outer region (124) has a plurality of spiral recesses (116) and a wall part (114) is arranged between two spiral recesses (116), characterized that the drill (10) comprises at least four main cutting edges (300), in particular comprises exactly four main cutting edges (300) and / or the drill (10) comprises at least three central cutting edge sections (210).

2. Drill (10) according to claim 1, characterized in that the drill (10) based on a position and / or formation of the main cutting edges (300) with respect to a rotation through 360 ° / l \ l around the drill axis (14 ) is rotationally symmetrical, where N is the number of main cutting edges.

3. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one main cutting edge (300), in particular each of the main cutting edges (300), comprises a main cutting edge outer section (302) running in the outer region (124), in particular at least one main cutting edge outer section (302), in particular each of the Main cutting edge outer sections (302) run completely through the outer region (124) in the radial direction to the drill axis (14).

4. Drill (10) according to one of the preceding claims, characterized in that at least one main cutting edge (300), in particular each of the main cutting edges (300), at least in sections, in particular with its main cutting edge outer section (302) completely, along a radial extent of one of the wall parts (114) runs.

5. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one main cutting edge (300), in particular each of the main cutting edges (300), comprises a main cutting edge core section (304) which runs in the core region (122).

6. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one main cutting core section (304), in particular each main cutting core section (304), runs along a respective core recess (156) of the base body (12) in the core region (122).

7. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one of the core recesses (156) forms a taper with one of the spiral recesses (116), in particular each of the core recesses (156) with a respective spiral recess (116) each forms a taper.

8. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one main cutting core section (304) runs along a core wall part (152), in particular each main cutting core section (304) runs along a respective core wall part (152).

9. drill (10) according to any one of the preceding claims, characterized

characterized in that for at least one of the main cutting edges (300), in particular for each main cutting edge (300), its main cutting edge core section (304) and its main cutting outer section (302) merge.

10. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one central cutting section (210), in particular each central cutting section (210), extends radially inward to the drill axis (14) up to a front tip (176).

11. Drill (10) according to one of the preceding claims, characterized

characterized in that in at least one of the central cutting sections (210), in particular in each central cutting section (210), a central free surface (214) of the base body (12) extends at a central clearance angle (ZF) up to the central cutting section (210), wherein the central clearance angle (ZF) between the central clearance surface (214) and a geometric reference plane running perpendicular to the drill axis is measured and the central clearance angle (ZF) is at least 3 ° and / or at most 25 °.

12. Drill (10) according to one of the preceding claims, characterized

characterized in that in at least one of the central cutting sections (210), in particular in each central cutting section (210), a central cutting surface (212) of the base body (12) extends at a central cutting angle (ZS) up to the central cutting section (210), the central cutting angle (ZS) is measured between the central rake surface (212) and a geometric radial reference surface, which runs parallel to the drill axis (14), and the central rake angle (ZS) is at least -5 ° and / or at most 20 °, where negative values of the central rake angle (ZS) correspond to an undercut of the central cutting section (210).

13. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one central cutting section (210), in particular each central cutting section (210), to the drill axis (14) extends at an increase angle (A) which is at least 5 ° and / or at most 40 °, the increase angle (A) being measured between the course of the central cutting edge section (210) and the radial direction of the drill axis (14) becomes.

14. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one of the main cutting edges (300), in particular each of the main cutting edges (300), comprises a main cutting edge central section (306) which runs in a central region (166) which is central to the drill axis in the radial direction.

15. Drill (10) according to one of the preceding claims, characterized

characterized in that at least in one of the main cutting edges (300), in particular in each of the main cutting edges (300), their main cutting edge central section (306) merges into their main cutting edge core section (304).

16. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one of the main cutting edge central sections (306) is formed by one of the central sections (210), in particular that each of the main cutting edge central sections (306) is formed by a respective central section (210).

17. Drill (10) according to one of the preceding claims, characterized

characterized in that at least one of the wall parts (114), in particular each of the wall parts (114), has an auxiliary cutting edge (144).

18. Drill (10) according to the preceding claim, characterized in that the secondary cutting edge (144) runs essentially along a spiral shape of the wall part (114) on the outside (132) thereof.

19. Drill (10) according to one of the preceding claims, characterized

characterized in that a radius (86) of the base body in the drilling section (24) at least 15% and / or at most 45% runs through the core area (122).

20. Drill (10) according to one of the preceding claims, characterized

characterized in that a radius (126) of the core area (122) runs at least 15% and / or at most 50% through the central area (166) of the core area (122).

21. Drill (10) according to one of the preceding claims, characterized

characterized in that the base body (12) has a larger radius (56) in the area of a fastening section (22) than in the drilling section (24).

22. Drill (10) according to one of the preceding claims, characterized

characterized in that the drill (10) has a cooling device (432) with a cooling channel (412) or with a plurality of cooling channels (412).

23. Drill (10) according to the preceding claim, characterized in that at least one cooling channel (412) runs through one of the wall parts (114) at least in sections.

24. Drill (10) according to one of the two preceding claims, characterized in that at least one cooling channel (412) extends at least approximately along the entire spiral extension of one of the wall parts (114).

25. Drill (10) according to one of the three preceding claims, characterized in that at least one cooling channel (412) runs on an outer side (54) of the fastening section (22).