Cutting tool and indexable insert

Abstract

The invention relates to a cutting tool (10), in particular a chamfering tool. Said tool comprises a tool body (14) which is rotatable about a tool axis (12) and a chamfer cutting element (24) which is mounted on the tool body (14) such that it is radially displaceable by means of a guide (32). The chamfer cutting element (24) is held in radial direction on the tool body (14) by means of a holding arm (42). The holding arm (42) is elastically flexible in radial direction and is disposed at least partly inside a substantially axially extending groove (56) provided on an outer periphery of the tool body (14). Also presented is an indexable insert (30) for such a cutting tool (10).

Claims

1. Cutting tool comprising a tool body which is rotatable about a tool axis, a chamfer cutting element which is mounted on the tool body such that it is radially displaceable by means of a guide, wherein at least one forward chamfer cutting edge and at least one reverse chamfer cutting edge are provided on the chamfer cutting element, and a holding arm separate from the chamfer cutting element, which holds the chamfer cutting element in radial direction on the tool body and is elastically flexible in radial direction, wherein the holding arm is disposed at least partly inside a substantially axially extending groove provided on an outer periphery of the tool body.

2. Cutting tool according to claim 1, wherein a cutting bit is disposed on a front end of the tool body.

3. Cutting tool according to claim 1, wherein the holding arm extends substantially in axial direction.

4. Cutting tool according to claim 3, wherein the holding arm comprises a first, axially forward end, which engages in an associated depression on the chamfer cutting element.

5. Cutting tool according to claim 3, wherein the holding arm comprises a second, axially rear end, which is fastened to the tool body.

6. Cutting tool of claim 3, wherein a recess is provided on the tool body adjacent in radial direction to at least one axially forward region of the holding arm and is configured to receive the holding arm in the event of a radially inward elastic deformation.

7. Cutting tool according to claim 6, wherein the recess extends from the axially forward end of the holding arm over at least 50% of the length of the holding arm.

8. Cutting tool according to claim 6, wherein a bending abutment element for the holding arm is disposed inside the recess, and wherein the bending abutment element s mounted on the tool body such that it is axially adjustable.

9. Cutting tool according to claim 1, claims, wherein the guide is formed by a guide channel which extends in radial direction in the tool body, into which at least a portion of the chamfer cutting element is inserted, wherein the guide channel is open on one side.

10. Cutting tool according to claim 1, wherein the tool body comprises a cooling channel which extends substantially axially and substantially over the entire length of the tool body.

11. Cutting tool according to claim 1, wherein the chamfer cutting element is an indexable insert.

12. Cutting tool according to claim 1, wherein the holding arm is strip-shaped.

13. Cutting tool according to claim 1, wherein that a stop element is provided on the tool body for limiting a displacement path of the chamfer cutting element radially outward.

14. Cutting tool according to claim 13, wherein the stop element is adjustable in its radial position.

15. Indexable insert for a cutting tool according to claim 1, wherein an indexable insert body comprises, on each of two opposite sides, a depression which is configured to interact with one end of a holding arm, wherein the depressions are offset to one another along a direction parallel to the two opposite sides, or comprises two depressions on one side, which are configured to interact with one end of a holding arm.

16. Cutting tool of claim 5, wherein the second, axially rear end is clamped or screwed to the tool body.

17. Cutting tool of claim 7, wherein the recess extends over at least 65% of the length of the holding arm.

18. Cutting tool of claim 10, wherein the cooling channel is fluidly connected to the guide channel.

19. Cutting tool of claim 12, wherein the holding arm is configured as a sheet metal strip.

20. Cutting tool of claim 14, wherein the stop element is a stop screw which is screwed radially into the tool body.

Description

[0030] The invention is explained below with the aid of different design examples, which are shown in the accompanying drawings. The figures show:

[0031] FIG. 1 a cutting tool according to the invention comprising an indexable insert according to the invention in a side view,

[0032] FIG. 2 the cutting tool and the indexable insert of FIG. 1 in a partly sectional illustration along Line II-II in FIG. 1,

[0033] FIG. 3 in a schematic illustration, the cutting tool of FIGS. 1 and 2, wherein an adjustable bending abutment element is in a changed position compared to FIG. 2,

[0034] FIG. 4 an illustration corresponding to FIG. 3, wherein the bending abutment element is still in a changed position,

[0035] FIG. 5 a portion of a cutting tool according to the invention according to an alternative embodiment, which comprises an indexable insert according to an alternative embodiment, in a partly sectional illustration,

[0036] FIG. 6 the indexable insert according to the invention of the cutting tool of FIGS. 1 to 4 in an isolated illustration, and

[0037] FIG. 7 the indexable insert according to the invention of the cutting tool of FIG. 5 in an isolated illustration.

[0038] FIG. 1 shows a cutting tool 10 comprising a tool body 14 which is rotatable about a tool axis 12.

[0039] It comprises a rear tool shank side end 16 and a front tool tip side end 18.

[0040] A drill tip 20 made of hard metal is fixedly connected to the tool body 14 on the tool tip side end 18. A plurality of cutting bits 22 are provided on the drill tip 20.

[0041] A chamfer cutting element 24 is furthermore provided on the tool body 14.

[0042] It comprises a forward chamfer cutting edge 26 and a reverse chamfer cutting edge 28.

[0043] The chamfer cutting element 24 is implemented as an indexable insert 30.

[0044] The cutting tool 10 is thus suitable both for drilling a hole and for creating chamfers on the edges of the hole. It is therefore a combination drilling-chamfering tool.

[0045] The chamfer cutting element 24 is mounted on the tool body 14 such that it is radially movable by means of a guide 32.

[0046] The guide 32 is formed by a guide channel 34 which extends in radial direction inside the tool body 14. It is radially open on one side (in the illustration according to FIG. 2 at the top).

[0047] A portion of the chamfer cutting element 24 is inserted into this guide channel 34.

[0048] A cross-section of the guide channel 34 corresponds substantially to a cross-section of the chamfer cutting element 24 along a guide channel center axis. Movements of the chamfer cutting element 24 beyond the radial mobility are thus excluded.

[0049] Since the guide channel 34 is open on only one side, a radially inward mobility of the chamfer cutting element 24 is limited as well.

[0050] In order to also limit the radially outward mobility of the chamfer cutting element 24, a stop element 36 in the form of a stop screw 38, which is screwed into the tool body 14 in radial direction, is provided on the tool body 14.

[0051] The stop screw 38 is implemented such that its screw head 40 limits a displacement path of the chamfer cutting element 24.

[0052] The position of the stop element 36 can be adjusted by screwing the stop screw 38 further or less far into the tool body 14.

[0053] The chamfer cutting element 24 is furthermore held in radial direction on the tool body 14 by means of a holding arm 42.

[0054] The holding arm 42 is separate from the chamfer cutting element 24.

[0055] It is also essentially strip-shaped.

[0056] In the embodiment shown, the holding arm 42 is configured as a sheet metal strip.

[0057] The holding arm 42 extends substantially in axial direction.

[0058] Moreover, a first, axially forward end 44 of the holding arm 42 engages in an associated depression 46 on the chamfer cutting element 24.

[0059] A second, axially rear end 48 of the holding arm 42 is fastened to the tool body 14.

[0060] In the embodiment shown, the rear end 48 is fixed to the tool body 14 by means of a fastening plate 50 which is oriented transversely to the holding arm 42. The fastening plate 50 is mounted on the tool body 14 by means of two screws 52, 54. The holding arm 42 is clamped between the fastening plate 50 and the tool body 14.

[0061] The holding arm 42 is disposed entirely inside a groove 56, which is provided on the tool body 14 and extends substantially axially.

[0062] The holding arm 42 is thus always located inside a substantially cylinder jacket shaped envelope surface, which corresponds to an outer periphery of the portions of the tool body 14, which are configured to come into contact with the workpiece during drilling. These portions are in particular located axially between the tool tip side end 18 and the fastening plate 50.

[0063] The holding arm 42 therefore does not project in radial direction relative to the tool body 14.

[0064] The holding arm 42 is also configured to be elastically flexible in radial direction.

[0065] Using this property, the holding arm 42 in the embodiment shown pretensions the chamfer cutting element 24 in radial direction against the stop element 36.

[0066] Therefore, in a neutral position (see FIGS. 1 and 2), the chamfer cutting element 24 rests against the screw head 40 of the stop screw 38 under pretension. In this context, the first end 44 of the holding arm 42 also rests against a radially outer boundary surface of the depression 46 of the chamfer cutting element 24.

[0067] To enable the holding arm 42 to also move inward in radial direction as needed, a recess 58 is provided on the tool body 14 adjacent to its axially forward region. Said recess is configured to receive the holding arm 42 in the event of a radially inward elastic deformation.

[0068] In the example shown, the recess 58 extends from the front end 44 of the holding arm 42 over approximately 80% of the length of the holding arm 42.

[0069] The recess 58 is furthermore configured as a recessed portion of the groove 56.

[0070] A bending abutment element 60 is disposed inside the recess 58. The holding arm 42 rests against it in the neutral state (see FIG. 2).

[0071] In the event that the holding arm 42 is to be bent radially inward, bending can take place in a region between the first end 44 and the bending abutment element 60.

[0072] The portion of the holding arm 42 which projects relative to the bending abutment element 60 in the direction of the first end 44 thus represents a type of cantilever beam.

[0073] The forces required for elastic deformation of the holding arm 42 are in particular dependent on a length of the portion which projects relative to the bending abutment element 60.

[0074] To control this, the bending abutment element 60 is mounted on the tool body such that it is axially adjustable (see FIGS. 2 to 4).

[0075] For this purpose, the bending abutment element 60 is configured as an abutment plate comprising a total of three fastening openings 62.

[0076] A fastening pin 64 is additionally provided on the tool body 14 for fastening the bending abutment element 60.

[0077] A size of the portion of the holding arm 42 which projects relative to the bending abutment element 60 can thus be adjusted by connecting the bending abutment element 60 to the fastening pin 64 using different fastening openings 62. In this context, FIGS. 2 to 4 show different positions.

[0078] The number of three fastening openings 62, which selectively interact with the fastening pin 64, is to be understood as an example. Of course, more or fewer than three fastening openings 62 can be provided as well, which results in more or fewer than three adjustable positions of the bending abutment element 60.

[0079] The distances between the fastening openings 62 can also be selected substantially freely. It is therefore possible to provide a cutting tool 10 depending on the specific application, in which the distances between the fastening openings 62 are of a suitable size.

[0080] The cutting tool 10 is also provided with a cooling channel 66 which extends substantially axially and substantially over the entire length of the tool body 14. Any coolant can be conducted to the cutting bits 22 via this cooling channel.

[0081] The cooling channel 66 is furthermore fluidically connected to the guide channel 34. Coolant can thus also be conducted to the forward chamfer cutting edge 26 and to the reverse chamfer cutting edge 28 of the chamfer cutting element 24.

[0082] The cutting tool 10 according to FIGS. 1 to 4 can be operated as follows.

[0083] The cutting tool 10 is set in rotation about the tool axis 12 and moved in the direction of a workpiece to be machined.

[0084] As soon as the cutting bits 22 come into contact with the workpiece, they begin to drill a hole. The cutting tool 10 is moved along the tool axis 12 in the direction of the workpiece in accordance with the drilling progress.

[0085] As soon as the workpiece and the cutting tool 10 assume a relative position in which the forward chamfer cutting edge 26 comes into contact with the workpiece, said cutting edge begins to produce a chamfer on an entry-side edge of the hole.

[0086] In doing so, cutting forces act on the chamfer cutting element 24.

[0087] As soon as the cutting forces acting in radial direction in this context exceed the pretensioning force applied to the chamfer cutting element 24 by means of the holding arm 42, the chamfer cutting element 24 is displaced radially inward, into the tool body, with elastic deformation of the holding arm 42.

[0088] If a through-bore is being produced by means of the cutting tool 10, the chamfer cutting element 24 does not leave this back-shifted position until it exits the bore on a side of the bore opposite to the entry side. Then, as in the neutral state, it is radially pretensioned against the stop element 36 by means of the holding arm 42.

[0089] In order to now produce a chamfer on the side of the bore opposite to the entry side, the cutting tool 10 has to be moved back along the tool axis 12. The reverse chamfer cutting edge 28 can then produce a chamfer on the associated edge of the bore.

[0090] Again, among others, cutting forces act on the chamfer cutting element 24 in radial direction. As soon as these exceed the pretensioning introduced by means of the holding arm 42 into the chamfer cutting element 24, the chamfer cutting element 24 shifts back into the interior of the tool body 14 and the cutting tool 10 can be removed from the bore along the tool axis 12.

[0091] It is thus possible, in a single machining step, to produce a through-bore in which both the entry or insertion-side edge and the exit-side edge are provided with a chamfer.

[0092] An alternative embodiment of the cutting tool 10 is shown in FIG. 5.

[0093] Only the differences to the first embodiment according to FIGS. 1 to 4 will be discussed. The same or corresponding components are provided with the same reference signs.

[0094] In the alternative embodiment, the holding arm 42 is produced in one piece with a clamping portion 68 which projects at a substantially right angle from it.

[0095] Said clamping portion is disposed in a recess 70 of the tool body 14 and clamped there by means of a frustoconical clamping element 72, which is fastened to the tool body 14 by means of a clamping screw 74.

[0096] The bending abutment element 60 is now also changed compared to the first embodiment.

[0097] It comprises a fastening extension 60a, which can selectively be inserted into an associated fastening groove 75a, 75b, 75c or 75d on the tool body 14.

[0098] Therefore, in order to set a size of the portion of the holding arm 42 which projects relative to the bending abutment element 60, the fastening extension 60a of the bending abutment element 60 can be inserted into a suitable fastening groove 75a to 75d.

[0099] In this context, the number of four fastening grooves 75a to 75d is also to be understood as an example. The same applies to the distances between the fastening grooves 75a to 75d, which can be selected depending on the application.

[0100] The fastening extension 60a and the fastening grooves 75a to 75d preferably create a press fit, so that the bending abutment element 60 is held securely on the tool body 14.

[0101] In all other respects, reference can be made to the explanations relating to the first-mentioned embodiment.

[0102] It goes without saying that constructive elements, which are shown in one of the two embodiments, can also be combined in other ways. In particular, the bending abutment element 60 according to the second embodiment can also be used together with a holding arm 42 according to the first embodiment. Likewise, the bending abutment element 60 according to the first embodiment can be used in combination with the holding arm 42 according to the second embodiment.

[0103] FIGS. 6 and 7 show the indexable inserts 30 used in the two embodiments of the cutting tool 10 in detail.

[0104] Each of the indexable inserts 30 comprises a total of two depressions 46, which are configured to interact with the end 44 of the holding arm 42.

[0105] The two indexable inserts 30 can thus respectively be used in two installation positions. In each of these installation positions, a forward chamfer cutting edge 26 and a reverse chamfer cutting edge 28 are available.

[0106] In total, therefore, the two indexable inserts 30 comprise two forward chamfer cutting edges 26 and two reverse chamfer cutting edges 28.

[0107] The indexable inserts 30 according to FIGS. 6 and 7 differ only with respect to the arrangement of the depressions 46, and thus with respect to the movement of the indexable insert 30, which is necessary, starting from a position in which one of the depressions 46 is coupled to the end 44 of the holding arm 42, to reach a position in which a respective other one of the depressions 46 can be coupled to the end 44 of the holding arm 42.

[0108] In the embodiment according to FIG. 6, the two depressions 46 are positioned on opposite sides of the indexable insert 30 and are also offset to one another in a direction 76 parallel to the two opposite sides.

[0109] In the embodiment according to FIG. 6, the two depressions 46 are configured on the same side.

[0110] It goes without saying that the embodiments according to FIG. 6 and FIG. 7 can also be combined. A resulting indexable insert 30 is thus provided with a total of four depressions 46 and comprises a total of four forward chamfer cutting edges 26 and four reverse chamfer cutting edges 28. The indexable insert 30 can consequently be used in four different installation positions.