EP2493646A1

EP2493646A1 - Multiplex exchangeable cutting plate for a drilling tool

Info

Publication number: EP2493646A1
Application number: EP10784436A
Authority: EP
Inventors: Horst Manfred JÄGER; Thilo Müller
Original assignee: Kennametal Inc
Current assignee: Kennametal Inc
Priority date: 2009-10-28
Filing date: 2010-10-12
Publication date: 2012-09-05
Also published as: CN104588740A; US20120282054A1; KR20120089694A; JP2013509308A; WO2011050903A1; BR112012009283A2; CN102574211B; CN102574211A; DE102009051073A1

Abstract

The invention relates to a multiplex exchangeable cutting plate (1) designed and suitable for use in a drilling tool, for an especially wide range of applications. The invention further relates to a drilling tool (12), which, when equipped with said exchangeable cutting plate, can be operated particularly effectively. The multiplex exchangeable cutting plate (1) comprises two end faces (3), which are plane-parallel to each other and perpendicular to a plate axis (2), and which have a substantially triangular outer contour. At each edge of the two end faces (3), a primary cutting edge (6) is formed, extending substantially over the entire length of the edge. Furthermore, the multiplex exchangeable cutting plate (1) has a design that is rotationally symmetrical with respect to a 120º rotation about the plate axis (2) and rotationally symmetrical with respect to a 180º rotation transversely to the plate axis (2). The drilling tool (12) comprises a first receptacle (18a) for the cutting plate (1). Said first receptacle (18a) is provided with a substantially triangular main contact surface (19) for contact with one of the end faces (3) of the cutting plate (1). Additionally, the main contact surface (19) is oriented at an angle between 90º and approximately 60º with respect to a tool axis (14) and extends in the region of one of the three edges directly up to the outer tool circumference (24).

Description

description

Multiple indexable insert for a drilling tool

Background of the invention

The invention relates to a multiple cutting insert for a drilling tool according to the preamble of claim 1. The invention further relates to a trained for receiving such a cutting tool and drilling tool on the combination of the drilling tool with the cutting plate. Finally, the invention also relates to the use of the cutting plate in the drilling tool.

In drilling tools, multiple cutting inserts, at least in an "outer cutting" position, in which the respective cutting plate cuts to the outer periphery of the drilling tool, are usually used in a "stationary" orientation with respect to the tool axis, namely such that the plate plane of the cutting insert is oriented approximately parallel to the tool axis , A corresponding drilling tool is known, for example, from EP 0 841 115 A1. In order to ensure the necessary clearance for the drilling of the cutting plate, so far cutting tools are mainly used in drilling tools, which are ground only on one side, which thus have only one main cutting edge per side surface. Such inserts have - with three- or quadrangular cross-section - at most three or four alternatively usable main cutting edges. For example, an insert known from EP 0 841 115 A1 has only two main cutting edges.

Deviating from EP 1 749 602 A2, a generic (multiple change) cutting insert with six main cutting edges is known. This cutting insert is designed for use in an associated drilling tool, in which the cutting insert can be inserted on the one hand into an outer receptacle and on the other hand into an inner receptacle. In the outer receptacle, through which the cutting plate in external cutting position is held, the cutting plate is again aligned as usual standing with respect to the tool axis. In contrast, in the inner receptacle in which the cutting insert is "internally cutting", thus held at a distance from the outer circumference of the tool, the cutting insert is oriented "horizontally" with respect to the tool axis so that its plane of the plate is oriented approximately perpendicular to the tool axis. The known cutting plate is formed asymmetrically in the direction of the plate axis and has in particular at its two end faces differently shaped main cutting edges. In each case one of these end faces is provided here as a contact surface on the bottom of a specific associated recording. The known insert is therefore used as intended only with a first end face in the outer receptacle. In this orientation, the cutting plate can be turned twice - namely rotated by 120 ° about its axis of the plate - are, wherein the three of the first end face opposite main cutting edges are worn. Subsequently, the known insert is intended implemented by the outer receptacle in the inner receptacle. For this purpose, the cutting plate is turned transversely to the plate axis and inserted in accordance with the second end face first in the second recording. In this position, the cutting plate can be turned twice again by 120 ° around its plate axis, until the other three main cutting edges are worn.

In each of the two shots of the drilling tool, the known cutting plate so each only has a triple benefit, so in each case only three main cutting available for change.

For use in milling or turning tools on the other hand from DE 1 232 436 A, WO 2007/149035 A1 or WO 2009/075633 A1 Mehrfachwendeschneidplatten known, in each of which each edge of both end faces is provided with a main cutting edge. These inserts are characterized by a particularly high multiple benefits. For example, in the case of a triangular plate cross-section, six main cutting edges can be provided on these cutting plates even with four-sided plate cross-section. These inserts are suitable for use in a conventional drilling tool, especially for use in external cutting position, but unsuitable.

Object of the invention

The invention has for its object to provide a designed for use in a drilling tool and particularly suitable Mehrfachwechselschneidplatte with particularly high multiple benefits. The invention is further based on the object of specifying a drilling tool that - equipped with this indexable insert - is particularly effective operable.

Solution of the task

With respect to the drilling tool, the above object is achieved according to the invention by the features of claim 6. Optional embodiments and further developments of the invention will become apparent from the dependent claims, the following description and the figures.

The cutting insert according to the invention has two plane-parallel and perpendicular to a plate axis end faces, each having a substantially triangular outer contour. At each edge of each of the two end faces, a main cutting edge is formed in each case. Overall, therefore, the cutting plate comprises six main cutting edges, each of these main cutting edges extending at least substantially over the entire edge length of the cutting insert. According to the invention, the cutting plate is both rotationally symmetrical with respect to a 120 ° - rotation about the plate axis and rotationally symmetrical with respect to a 180 ° - rotation transverse to the plate axis, ie with respect to a 180 ° rotation about an axis perpendicular to the plate axis axis of rotation formed. The cutting plate can thus be mapped six times exactly on itself as a result of these symmetry properties become. In other words, there are six different, but geometrically indistinguishable orientations of the insert.

The drilling tool according to the invention has at least one first receptacle for an insert of the type described above. This first receptacle comprises a substantially triangular main contact surface, which is designed as an abutment or counter-abutment surface for one of the end faces of the insert. The receptacle is positioned with respect to the drilling tool such that its main abutment surface is roughly approximately perpendicular, namely oriented at an angle between 90 ° and about 60 ° to a tool axis and extending in the region of one of its corners directly to the tool outer circumference. In other words, the first receptacle is designed to support the cutting plate arranged in the intended position in a lying position and an outer cutting position.

In principle, the drilling tool can have only a single receptacle for the cutting insert, especially in the case of small-sized designs. Preferably, however, several, in particular two receptacles are provided on the drilling tool, in each of which an insert of the type described above can be inserted. All of these recordings can be arranged for the outer cutting positioning of the cutting plate. In this case, the drilling tool thus comprises a plurality of "first" receptacles in the sense of the preceding embodiments, in which case the drilling tool preferably comprises a central pilot between the receptacles, the main cutting edges of which process an inner region of the bore.

In an alternative embodiment, in contrast to the "first" receptacle, the drilling tool comprises a "second" receptacle for an insert of the type described above, this second receptacle being offset radially inwardly relative to the first receptacle and thus designed for internally cutting positioning of the insert. This second receptacle also preferably has a shape which is substantially complementary to the cutting insert, in particular a substantially triangular main contact surface. che, which in turn is designed as an abutment or counter-bearing surface to an end face of the cutting plate.

The above-described symmetry properties of the cutting plate makes it possible to insert the cutting plate in six different orientations in the same receptacle, and thus in particular to use all six main cutting edges of the cutting insert already in the outer cutting position. The use of the cutting edge provided on both sides with main cutting edges in the outer cutting position of a drilling tool is made possible or at least usefully by the idea of not mounting the cutting plate here - as usual - standing, but lying. The horizontal positioning in external cutting position is in turn made possible by the triangular shape of the cutting plate.

If the drilling tool in addition to the "first" recording includes a "second" recording in the sense of the above definition, the cutting plate formed according to the invention can be used even twelve times. As is known, the respectively active main cutting edge of the cutting insert in the outer cutting position is primarily worn in the outer corner region, while the main cutting edges in an inner region would be significantly longer usable. In the inner cutting position, however, these outer corner areas are only relatively weakly stressed. The insert initially used in external cutting position can therefore still be used after wear of all six outer corner areas six times in the inner cutting position.

By "outside cutting", this again refers to a position of the cutting plate in which it cuts to the outer circumference of the tool, in contrast to which the cutting insert is "spaced apart" from the outer circumference of the tool in an "internal cutting" position.

In this case, a position of the cutting plate is again referred to as "lying", in which the plate axis is approximately parallel, and the plate plane is approximately perpendicular to the tool axis, in contrast to which "standing" in the following In turn, a position of the cutting plate referred to, in which the plate axis approximately perpendicular, and the plate plane are aligned approximately parallel to the tool axis.

The indications "approximately triangular" or "substantially triangular", based on the end faces of the cutting plate or the main bearing surfaces of the first and second receptacle, are to be understood as coarse-grained indications. In particular, in the region of the corners, the end faces of the cutting plate in the invention may deviate from an exact triangular shape. Thus, the end faces in the region of the corners are even preferably "cut off" or rounded off by coverings.Furthermore, the main cutting edges may have a slight curvature in the context of the invention.The main bearing surface of the first or second receptacle is "substantially triangular" in the context of this application always if the corresponding cutting plate is insertable into it in such a way that the cutting plate is accommodated in the receptacle in a form-fitting and non-rotatable manner about the plate axis. Deviations from an exact triangular shape can in particular occur in the area of the corners in the case of the main contact surface within the scope of the invention. In particular, individual corners of the "substantially triangular" main abutment surface are preferably cut off or hollowed out.

Accordingly, the statements "approximately" and "substantially" are also to be understood in other context as an indication that the relevant information in the context of the invention is coarse-grained, so that it does not depend on an exact fulfillment of the respective statement. In particular, the main contact surface of the first receptacle "oriented essentially perpendicular to the tool axis is preferably not aligned exactly perpendicular to the tool axis but is set against the plumb line on the tool axis." In this case the angle of attack is between 1 ° and 30 °, preferably between 2 ° ° and 8 °, and in particular about 5 °.

The cutting plate is preferably designed such that between each end face and an adjacent region of the sides connecting the end faces. tenflächen an acute angle is formed. As a result, each of the six main cutting edges has a wedge angle that falls below 90 °.

In a preferred embodiment, the cutting plate is for this purpose formed of two identical part bodies, each having the shape of a truncated pyramid with a triangular base surface, wherein the base is formed in each case by one of the end faces. The two truncated pyramidal body parts are in this case the head side, i. with each smaller area directly or indirectly set together. In this embodiment, if the partial bodies are placed directly next to one another, then a groove tapering in the center plane of the dental incisor is formed in each of the three lateral surfaces. The term "part body" here is to be understood in a purely geometrical sense, the cutting plate, regardless of this choice of words, preferably being a one-piece object.

In an alternative embodiment of the cutting insert according to the invention deviating from this in each of the three end faces are each two parallel and separated by a central web Spanformnuten introduced, wherein one of these two Spanformnuten adjacent to a corresponding end face for the realization of the acute wedge angle.

In a preferred development of the cutting plate, in each end face a recess centered with respect to the plate axis, i. Well provided. As an alternative to a single recess, a structure formed from a plurality of recesses may also be provided in each end face. Due to the above-described symmetry properties of the cutting insert, the (single) recess is symmetrical with respect to a 120 ° rotation about the plate axis. In the case of several recesses per end face, these are to be distributed symmetrically around the plate axis.

These recesses act as intended with one or more complementarily shaped and arranged projections in the main bearing surface of the (first or second) receiving an associated configuration of the drilling tool together. The recesses and projections are hereby matched to one another so that they engage positively in one another, and thus fix the cutting plate transversely to the plane of the end faces or to the plane of the main bearing surface. If the cutting plate - as usual - has a central passage for screwing the cutting plate in the receptacle, the said recess is dimensioned such that it protrudes radially beyond the diameter of the bore. Through the recesses and the corresponding projections at least a portion of the forces acting on the cutting plate in operation transverse forces is introduced into the drilling tool. The side walls of the receptacle and possibly existing screw are relieved thereby. This is particularly important for the first shot, whose outside wall due to the close proximity arrangement of this recording forcibly has only a comparatively small thickness, so that under the action of shear forces here a particularly high material load is expected. By the recesses and the corresponding projections thus the load capacity of the drilling tool is substantially improved and counteracted tool breakage in case of overload effectively.

If only one central recess is provided in each end face of the cutting insert, this recess preferably has a non-circular cross-section with a 120 ° rotational symmetry with respect to rotation about the plate axis. The recess in this embodiment has e.g. the contour of an equilateral triangle, or a star. Due to the non-circular cross-section of the formed between the or each recess and each in turn complementarily shaped projection of the main bearing surface positive engagement causes a rotationally fixed mounting of the cutting plate in the recording. As a result, the tangential forces that may be acting on the cutting disc are at least partially introduced via the projections into the drilling tool. The side walls of the recording are thereby relieved in turn. The recess and the corresponding projection can basically also have a round cross-section.

The second receptacle is formed in a convenient embodiment of the drilling tool, as well as the first receptacle for holding the cutting plate in a lying position. Accordingly, the main bearing surface of the second shot in this embodiment in turn aligned substantially perpendicular to the tool axis. In an alternative embodiment, however, the cutting plate is fixed as intended standing in the second receptacle. In this case, the main bearing surface of the second receptacle is arranged substantially parallel to the shaft axis. In this case too, the terms "substantially perpendicular" and "substantially parallel" are to be understood as coarse-grained indications which permit a slight adjustment of the main abutment surface relative to the shaft axis or the solder thereon.

In a comparatively simple embodiment of the drilling tool, the or each projection in the main bearing surface of the first or second receptacle is formed integrally with the wall of the associated receptacle. In a particularly advantageous variant of the drilling tool, however, the or each projection is part of a separate intermediate piece, which can be inserted approximately in the manner of a washer between the main bearing surface and the cutting plate. In order to be able to transfer transverse and optionally tangential forces from the cutting plate into the drilling tool, the intermediate piece and the main bearing surface are in turn designed such that they engage with one another in a form-fitting manner.

The formation of the or each projection on the separate intermediate piece has the particular advantage that the intermediate piece can be made of a different material than the rest of the drilling tool. Conveniently, the intermediate piece is formed here in particular in terms of a particularly high wear resistance of a harder material than the main bearing surface. The separate intermediate piece has the particular advantage that it can be easily replaced when worn, while the remaining components of the drilling tool can continue to be used. The intermediate piece also has the positive side effect of protecting the receptacle against erosion by coolant and chip abrasion. For this purpose, it is suitably dimensioned in such a way that it terminates in the assembled state with a side wall approximately flush with the wall of a flute. The above object is further achieved by a drilling tool of the type described above, in whose recording or recording Geweils) a cutting plate of the type described above is used. In another formulation, the above object is also achieved by the use of a cutting insert of the type described above as an insert in a drilling tool of the type described above.

Description of the figures

Embodiments of the invention will be explained in more detail with reference to a drawing. Show:

1 is a perspective view of a Mehrfachwechselschneidplatte,

2 shows a perspective view of a drilling tool with two receptacles, in each of which the insert according to FIG. 1 can be inserted,

3 is a perspective view of the drilling tool of FIG. 2 in a contrast rotated orientation,

2 in the representation according to FIG. 3 the drilling tool according to FIG. 2 with two inserts inserted into the receptacles according to FIG. 1, FIG.

3 in the illustration of FIG. 3, the drilling tool according to FIG. 2 with inserts inserted in a variant of FIG. 1, FIG.

6 is a representation according to FIG. 3 of a modified embodiment of the drilling tool with two inserted inserts according to FIG. 5, FIG.

7 shows a representation according to FIG. 2 of a further embodiment of the drilling tool, FIG.

Fig. 8 in illustration of FIG. 3 shows another embodiment of the drilling tool with inserts inserted according to FIG. 5, and

Fig. 9 is a schematic representation of the cutting plate according to FIG. 1 with various details for positioning the same with respect to the drilling tool. Corresponding parts and sizes are always provided with the same reference numerals in all figures.

Description of the embodiment

The (Mehrfachwechsel-) insert 1 shown in Fig. 1 has transversely to a plate axis 2 approximately a cross section in the form of an equilateral triangle. Viewed in the direction of the plate axis 2, the cutting plate 1 is bounded by two end faces 3, which are connected by three side surfaces 4 ^.

Each of the two end faces 3 has approximately the shape of an equilateral triangle again, but the corners of the triangular shape are "cut off" or rounded off by bevels 5. The edges forming the transition between the end faces 3 to the surrounding side faces 4 are over the whole The cutting edge 1 comprises correspondingly six main cutting edges 6. A corresponding secondary cutting edge is formed in each of the main cutting edges 6 on the side edges of the cutting plate 1 connecting each side surface 4. In the interior, each end face 3 is provided with a relative to the plate axis 2 centered recess 7. The recess 7 has the shape of an equilateral triangle aligned in the same direction with the respective end face 3.

The cutting plate 1 is also coaxial with the plate axis 2 with a central bore 8 passes. The two mouths of the bore 8 are in each case inscribed in the respective recess 7, so affect the walls of the recesses 7 on all three sides.

The cutting plate 1 has a total of approximately the shape of a body composed of two partial bodies 9, wherein the partial bodies have the shape of truncated pyramidal stumps and head to head, ie with the respective small neren surface, are directly juxtaposed. Each of the side surfaces 4 therefore consists of two partial surfaces which abut each other along the center plane 10 of the cutting plate 10 at an obtuse angle. As a result of the truncated pyramid shape of the partial body 9, an acute angle is always formed between each end face 3 and respectively adjacent partial surfaces of the lateral surfaces 4. As a result, each cutting edge 6 has a 90 ° under wedge angle.

In the embodiment shown in FIG. 1, the two end faces 3 are aligned, so that each two the same side surface 4 bounding main cutting edges 6 are parallel. Deviating from this, however, the two end faces 3 can also be slightly rotated relative to each other about the plate axis 2.

In any case, however, the insert 1 is formed symmetrically with respect to a 120 ° rotation about the plate axis 2. In addition, the cutting plate 1 is formed symmetrically with respect to a 180 ° rotation about a rotation axis 11 perpendicular to the plate axis 2.

In the illustrated embodiment of the cutting plate 1, the axis of rotation 11 runs within the center plane 10 through an (arbitrary) corner of the cutting plate 1 and through the intersection of the plate axis 2 with the median plane 10th

As a result of the described symmetry properties, the cutting insert 1 can be imaged six times on itself. In other words, in addition to the orientation of the cutting insert 1 shown in FIG. 1, there are five further orientations which are geometrically indistinguishable from the representation selected in FIG.

The drilling tool 12 shown in FIGS. 2 and 3 comprises a roughly cylindrical shaft 13, in the lateral surface of which two coiled flutes 15 are formed, which are diametrically opposed to a tool axis 14. 2 and 3 show a section of a head portion of the shaft 13, which represents the actual working tip of the drilling tool 12. As can be seen from FIGS. 2 and 3, the flutes 15 terminate in a head-side end face 16 and subdivide them into two subsections designated below as free faces 17 a and 17 b. In each of the free surfaces 17a and 17b in this case a receptacle 18a and 18b is introduced, in each of which an insert 1 is used. In the embodiment according to FIGS. 2 and 3, the drilling tool 12 itself has no cutting edges. Rather, it merely serves as a holder for the cutting plates. 1

Each of the receptacles 18a and 18b has a main abutment surface 19 corresponding in its shape to the end faces 3, thus approximately in the form of an equilateral triangle, which serves as an abutment or counter abutment surface for one of the end faces 3. The main bearing surface 19 of each receptacle 18a, 18b is surrounded on both sides by side walls 20a and 20b. Towards the third side, each of the receptacles 18a and 18b is open towards the flute 15 leading in each case in the intended direction of rotation of the drilling tool 12.

The respective main contact surface 19 of the receptacles 18a and 18b is provided in its center in each case with a threaded bore 21, which corresponds to the through hole 8 of the associated cutting plate 1. The threaded hole 21 is surrounded in each case by an equilateral triangle forming projection 22. Each of the projections 22 is in this case formed complementary to the recesses 7 of the cutting plate 1 and acts as intended with one of these recesses 7 to form a positive connection together.

It can also be seen from FIGS. 2 and 3 that the inner corner and the trailing corner of each receptacle 18a and 18b are hollowed out in order to form free space for the corresponding corner areas of the insert 1 to be inserted. Further, two mouths of channels 23 for cooling and / or lubricant can be seen in Fig. 2 and 3, wherein one of these channels 23 nachlegend to one of the receptacles 18a and 18b in the respectively associated free surface 17a and 17b opens. In the embodiment according to FIGS. 2 and 3, the two receptacles 18a and 18b are arranged radially offset relative to one another in the end face 16. The first receptacle 18a is arranged such that its outer corner extends directly to the outer circumference 24 of the shaft (generically also referred to as tool outer circumference). The receptacle 18a thus serves for externally-cutting positioning of the cutting insert 1. On the other hand, the second receptacle 18b is arranged in the end face 16 such that its outer corner is spaced apart from the outer circumference 24. This receptacle 18b thus serves for internal cutting positioning of the cutting insert 1. Both receptacles 18a and 18b are arranged in the exemplary embodiment according to FIG. 2 such that the cutting insert 1 is positioned in a lying position with respect to the tool axis 14. The main contact surfaces 19 of both receptacles 18 a and 18 b are aligned approximately perpendicular to the tool axis 14 accordingly.

FIG. 4 shows the drilling tool 12 with the cutting plates 1 inserted horizontally with respect to the tool axis 14 in the receptacles 18a and 18b. It can be seen in this representation, in particular, that each of the cutting plates 1 rests positively in the associated receptacle 18a or 18b, the side walls 20a and 20b of the receptacles 18a and 18b flank each two side surfaces 4 tight. Regardless of the two-sided contact of each insert 1 on the adjacent side walls 20a and 20b, the introduction of the forces acting on the cutting plates 1 and tangential to the respective plate axis 2 forces in the drilling tool 12 takes place primarily via a form fit between each between a recess 7 of each cutting 1 and the projection 22 engaging therein is formed. The side walls 20a and 20b of the receptacles 18a and 18b are thereby relieved. This is particularly important for the outer receptacle 18a, especially since - as can be seen in particular from FIG. 4 - whose outer side wall 20a has only a very small material thickness due to the proximity to the outer circumference 24.

In Fig. 4, two clamping screws 25 are also recognizable, which passed through the through hole 8 of an associated cutting plate 1, and in the underlying threaded bore 21 of the associated receptacle 18 a and 18b are bolted. The cutting plates 1 are thus clamped by the clamping screws 25 in the respective associated receptacle 18 a and 18 b.

5 shows the drilling tool 12 already described in connection with FIGS. 2 to 4 with inserts 1 inserted, wherein these inserts 1 are present here in a different form from FIG. 1 embodiment. The illustrated in Fig. 5 cutting plates 1 differ from the embodiment described in connection with Figure 1 in that in each side surface 4 instead of a single groove two parallel and separated by a central web 26 Spanformnuten 27 are provided. In each case one of the chip-forming grooves 27 adjoins an associated end face 3. The main cutting edge 6 formed between each end face 3 and the respectively adjacent chip forming groove 27 is thus in turn formed with an acute wedge angle.

Incidentally, the cutting plate 1 shown in FIG. 5 is similar to the embodiment described in connection with FIG. 1. In particular, the end faces 3 of this cutting plate 1 are optionally also provided with recesses 7, as shown in Fig. 1.

FIG. 6 shows a variant of the drilling tool 12. This differs from the embodiment described above essentially in that the second receptacle 18b has a tilted by 90 ° relative to the first receptacle 18a and according to the mounting of the

Cutting plate 1 is formed in a stationary position with respect to the tool axis 14. The receptacle 18b here correspondingly has a main contact surface 19, which is aligned approximately parallel to the tool axis 14, more precisely approximately in the axial-radial orientation. The drilling tool 12 is shown in FIG. 6 by way of example with inserted inserts 1 of the type shown in FIG. 5.

7 shows a further embodiment of the drilling tool 12. This third embodiment of the drilling tool 12 is similar, unless otherwise described below, the embodiment of FIG. 2 and 3. In contrast to the local embodiment is shown in FIG. 7 instead of the projections 22 in the main bearing surfaces 19 of the receptacles 18 a and 18 b but each provided a recess 28. In this embodiment, the drilling tool 12 additionally comprises two intermediate pieces 29. In each case one of the two intermediate pieces 29, which are of the same construction and of which only one is shown in FIG. 7 for the sake of simplicity, is designed in the manner of a washer between the corresponding main contact surface 19 and 19 inserted on the cutting plate 1 to be mounted. Each of the intermediate pieces 29 each has a (in the perspective of FIG. 7 facing away) back, with which the respective intermediate piece 29 is positively inserted into the respective corresponding recess 28. On a front side 30 opposite this rear side, which in turn is provided complementary to the recesses 7 of the cutting plate ΐ projection 22 is provided. Each intermediate piece 29 also has a central bore 31, through which one of the clamping screws 25 can be passed.

In the assembled state, the intermediate pieces 29 engaging on the one hand in the cutting plate 1 and on the other hand in the corresponding recess 28 thus mediate an indirect positive connection between the cutting insert 1 and the respective receiving receptacle 18a or 18b.

Each of the intermediate pieces 29 is dimensioned such that in the assembled state with a side face 33 it extends directly to the wall of the corresponding flute 15, and preferably terminates approximately flush with the flute wall. The side surface 33 forms a kind of skirt which protects the flute 15 in the area above the cutting plate 1 against chip abrasion.

FIG. 8 shows a further embodiment of the drilling tool 12. This differs from the above-described variants of the drilling tool 12 in that instead of an outer receptacle 18a and an inner receptacle 18b two radially symmetrically arranged receptacles 18a are provided, both for externally cutting positioning each of an insert 1 in a respect to the shaft axis 14 lying position are formed. In a radially inner region between the two receptacles 18 a, a so-called pilot 32 is provided here, which is equipped with its own NEN main and secondary cutting edges is provided. The pilot 32 is here as

integral part of the shaft 13 shown. The pilot 32 can also be designed as a separate and connectable to the shaft 13 part. The drilling tool 12 according to FIG. 8 differs from the embodiments described above further in that its two diametrically introduced into the lateral surface of the shaft 13 flutes 15 are not or only slightly coiled. Incidentally, the drilling tool 12 according to FIG. 8 also resembles the embodiments described above.

All illustrated embodiments of the drilling tool 12 can be equipped with both the cutting plates 1 in the embodiment of FIG. 1 and the modified inserts 1 in the embodiment of FIG. 5. In addition, the individual design features of the illustrated drilling tools 12 and inserts 1 - as far as possible - can be combined with each other.

FIG. 9 diagrammatically shows that the or each cutting plate 1 is not fixed exactly perpendicular to the tool axis 14, at least in the outer cutting position by the receptacle 18a, but in a position slightly inclined to the tool axis 14. The leading main cutting edge 6 of the cutting insert 1 in this case assumes an angle of attack α with respect to the solder on the tool axis 14, which in an advantageous dimensioning has an amount of between 2 ° and 8 °, preferably about 5 °. As a result of this inclination of the cutting insert 1, a sufficient clearance f of the cutting insert 1 in the region of the end face 16 remote from the end face 16 and thus inactive cutting face 3 is achieved.

In Fig. 9 is also seen that the cutting plate is also issued slightly in the tangential direction.

Claims

claims

1. Mehrfachwechselschneidplatte (1) for a drilling tool, with two

plane parallel to a plate axis (2) vertical end faces (3), each having a substantially triangular outer contour, wherein on each edge of the two end faces (3) each have a substantially over the entire edge length extending main cutting edge (6) is formed

marked by

a rotational symmetry with respect to a 120 ° rotation about the plate axis (2) in combination with a rotational symmetry with respect to a 180 ° rotation transverse to the plate axis (2).

2. cutting insert (1) according to claim 1,

marked by

two identical part bodies (9) each in the form of a truncated pyramid whose base is formed by a respective one of the end faces (3), and the head side are juxtaposed directly or indirectly.

3. cutting insert (1) according to claim 1 or 2,

marked by

three side surfaces (4) connecting the end faces (3), in each of which two parallel and by a central web (26) separate chip forming grooves (27) are introduced, one of which is adjacent to a corresponding end face (3).

4. cutting insert (1) according to one of claims 1 to 3,

characterized, in that in each end face (3) a recess (7) centered relative to the plate axis (2) or several recesses distributed around the plate axis (2) are provided.

5. cutting insert (1) according to claim 4,

characterized,

the recess (7) has a non-circular cross-section.

6. Drilling tool (12) with a first receptacle (18a) for an insert (1) according to one of claims 1 to 5, wherein the first receptacle (18a) has a substantially triangular main abutment surface (19) for engagement with one of the end surfaces (3 ) of the cutting insert (1), and wherein the main abutment surface (19) is aligned with a tool axis (14) at an angle between 90 ° and about 60 ° and extends in the region of one of its three corners directly to the tool outer circumference (24).

7. drilling tool (12) according to claim 6,

marked by

a second receptacle (18b) for a cutting insert (1) according to one of claims 1 to 5, wherein the second receptacle (18b) is arranged offset radially inwards relative to the first receptacle (18a).

8. drilling tool (12) according to claim 7,

characterized,

in that the second receptacle (18b) has a substantially triangular main abutment surface (19) for abutment with one of the end surfaces (3) of the cutting insert (1), and wherein this main abutment surface (19) is arranged substantially parallel to the tool axis (14).

9. drilling tool (12) according to any one of claims 6 to 8,

characterized, in that a projection (22) for positive engagement in the corresponding recess (7) of the cutting plate (1) formed according to claim 4 or 5 is formed in the main bearing surface (19).

10. drilling tool (12) according to claim 9,

characterized,

in that the projection (22) is part of an intermediate piece (29) which is separate from the main bearing surface (19) and can be inserted into the main bearing surface (19) in a form-fitting manner.

11. drilling tool (12) according to claim 10,

characterized,

the intermediate piece (29) is formed from another, in particular harder, material than the main bearing surface (19).

12. drilling tool (12) according to claim 10 or 11,

characterized,

in that the intermediate piece (29) can be inserted into the main contact surface (19) such that a side wall (33) of the intermediate piece (29) terminates approximately flush with the wall of a flute (15).

13. Drilling tool (12) according to any one of claims 6 to 12, with an insert in the or each receptacle (18 a, 18 b) insert (1) according to one of claims 1 to 5.

14. Use of an insert (1) according to any one of claims 1 to 5 as an insert in a drilling tool (12) according to any one of claims 6 to 12.