Rotary cutting tool

Abstract

A rotary cutting tool, in particular a drill, is described, which comprises a shank and an exchangeable cutting tip (14). For this purpose, a locking geometry having an undercut of a first type and a torque transmission geometry is provided on the shank. A locking projection having a torque transmission counter-geometry is provided on the cutting tip, wherein, in a mounted state, the locking projection engages in the undercut of the first type and the torque transmission counter-geometry abuts the torque transmission geometry. The rotary cutting tool further comprises a securing unit, which holds the cutting tip on the shank.

Claims

1. A rotary cutting tool comprising: a shank having an axis of rotation; an exchangeable cutting tip configured to be coupled to the shank, wherein the shank includes a locking geometry comprising a base body extending axially along the axis of rotation and a holding finger extending from a cutting tip-side end of the base body in a circumferential direction relative to the base body, the holding finger having a projecting section forming a first undercut and a second undercut, the locking geometry further comprising a torque transmission geometry oriented in the direction of rotation and including a flat torque transmission surface and a curved torque transmission surface, wherein the cutting tip includes a locking projection having a torque transmission counter-geometry comprising a flat torque transmission countersurface and a curved torque transmission countersurface, wherein, in a mounted state, the locking projection of the cutting tip engages both the first undercut of the shank to prevent pull-out of the cutting tip from the shank along the axis of rotation and the second undercut of the shank to counteract rotation of the cutting tip relative to the shank in a direction of rotation and to counteract a lifting away of the torque transmission counter-geometry from the torque transmission geometry, and the torque transmission counter-geometry abuts the torque transmission geometry; and loading means for holding the cutting tip on the shank, wherein the loading means comprises a clamping screw for elastically deforming the holding finger in the direction of the base body such that the locking projection of the cutting tip is clamped between the holding finger and an axial stop surface on the shank.

2. The rotary cutting tool of claim 1, wherein the rotary cutting tool comprises a drill.

3. A rotary cutting tool, comprising: a shank having an axis of rotation; an exchangeable cutting tip configured to be coupled to the shank, wherein the shank includes a locking geometry comprising a base body extending axially along the axis of rotation and a holding finger extending from a cutting tip-side end of the base body in a circumferential direction relative to the base body, the holding finger having a projecting section forming a first undercut and a second undercut, the locking geometry further comprising a torque transmission geometry oriented in the direction of rotation and including a flat torque transmission surface and a curved torque transmission surface, wherein the cutting tip includes a locking projection having a torque transmission counter-geometry comprising a flat torque transmission countersurface and a curved torque transmission countersurface, wherein, in a mounted state, the locking projection of the cutting tip engages both the first undercut of the shank to prevent pull-out of the cutting tip from the shank along the axis of rotation and the second undercut of the shank to counteract rotation of the cutting tip relative to the shank in a direction of rotation and to counteract a lifting away of the torque transmission counter-geometry from the torque transmission geometry, and the torque transmission counter-geometry abuts the torque transmission geometry; and loading means for holding the cutting tip on the shank, wherein the loading means comprises a clamping disc, which is disposed between the cutting tip and the shank such that, in the mounted state of the cutting tip, the holding finger of the shank is axially pressed against the locking projection of the cutting tip.

4. The rotary cutting tool according to claim 3, wherein the clamping disc is positioned on a side of the cutting tip facing away from the holding finger and the clamping disc comprises at least one support geometry for positioning the cutting tip on the shank.

5. The rotary cutting tool according to claim 4, wherein a first support geometry facing the shank and a second support geometry facing the cutting tip are different.

6. The rotary cutting tool according to claim 3, wherein the clamping disc is a component separate from the shank and the cutting tip.

7. The rotary cutting tool of claim 3, wherein the rotary cutting tool comprises a drill.

8. A rotary cutting tool, comprising: a shank having an axis of rotation; an exchangeable cutting tip configured to be coupled to the shank, wherein the shank includes a locking geometry comprising a base body extending axially along the axis of rotation and a holding finger extending from a cutting tip-side end of the base body in a circumferential direction relative to the base body, the holding finger having a projecting section forming a first undercut and a second undercut, the locking geometry further comprising a torque transmission geometry oriented in the direction of rotation and including a flat torque transmission surface and a curved torque transmission surface, wherein the cutting tip includes a locking projection having a torque transmission counter-geometry comprising a flat torque transmission countersurface and a curved torque transmission countersurface, wherein, in a mounted state, the locking projection of the cutting tip engages both the first undercut of the shank to prevent pull-out of the cutting tip from the shank along the axis of rotation and the second undercut of the shank to counteract rotation of the cutting tip relative to the shank in a direction of rotation and to counteract a lifting away of the torque transmission counter-geometry from the torque transmission geometry, and the torque transmission counter-geometry abuts the torque transmission geometry; and a securing unit for holding the cutting tip on the shank, wherein the securing unit comprises a securing pin, and an opening associated with the securing pin is provided on the cutting tip, wherein the securing pin extends axially from the shank and, in the mounted state of the cutting tip, engages in the opening.

9. The rotary cutting tool according to claim 8, wherein the securing pin comprises a pin shank and a pin head and the opening is provided with a third undercut, wherein the third undercut acts axially and the pin head is disposed inside the opening in a first rotational position of the cutting tip relative to the securing pin and engages in the third undercut in order to secure the cutting tip against an axial pull-out direction on the shank.

10. The rotary cutting tool according to claim 9, wherein the pin head has an oval cross-section and the opening of the cutting tip comprises a feed section which is designed with a corresponding oval cross-section, so that the pin head is configured to be inserted axially into the opening in a second rotational position, wherein the second rotational position differs from the first rotational position.

11. The rotary cutting tool according to claim 8, wherein the securing pin consists of two securing pin halves which are separated by an axial gap, wherein the securing pin halves are elastically deformable in a radial direction.

12. The rotary cutting tool of claim 8, wherein the rotary cutting tool comprises a drill.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained below with the aid of different design examples, which are shown in the accompanying drawings. The figures show:

(2) FIG. 1 a rotary cutting tool according to the invention according to a first embodiment in the form of a drill,

(3) FIG. 2 a shank of the rotary cutting tool of FIG. 1 in an isolated illustration,

(4) FIG. 3 a cutting tip of the rotary cutting tool of FIG. 1 in an isolated illustration,

(5) FIG. 4 a rotary cutting tool according to the invention according to a second embodiment in the form of a drill,

(6) FIG. 5 the rotary cutting tool of FIG. 4 during a mounting procedure,

(7) FIG. 6 a shank and a clamping disc of the rotary cutting tool of FIGS. 4 and 5 mounted on said shank in an isolated illustration,

(8) FIG. 7 the clamping disc of the rotary cutting tool of FIGS. 4 to 6 in an isolated illustration,

(9) FIG. 8 a rotary cutting tool according to the invention according to a third embodiment in the form of a drill during a mounting procedure in a perspective front view, and

(10) FIG. 9 the rotary cutting tool of FIG. 8 in a perspective rear view.

DETAILED DESCRIPTION

(11) FIGS. 1 to 3 show a rotary cutting tool 10 according to a first embodiment. The rotary cutting tool 10 is designed as a drill, which can be rotated about an axis of rotation 8.

(12) It comprises a shank 12, which is shown only in sections in FIG. 1, and a cutting tip 14 that is coupled to it in an exchangeable manner.

(13) For this purpose, a locking geometry 16 is provided on the shank 12.

(14) It comprises a base body 18, which extends substantially axially, i.e. along the axis of rotation 8.

(15) In addition to this, a holding finger 20 extends from a cutting tip-side end of the base body 18. Said holding finger extends substantially in circumferential direction relative to the axis of rotation 8 and projects relative to the base body 18. The holding finger 20 thus comprises a projecting section 22.

(16) In addition to this, the locking geometry 16 comprises a torque transmission geometry 24, which is oriented in a direction of rotation 26 of the rotary cutting tool 10 about the axis of rotation 8.

(17) In the embodiment shown, the torque transmission geometry 24 consists of a flat torque transmission surface 24a and a curved torque transmission surface 24b (see FIG. 2).

(18) The holding finger 20, more precisely the projecting section 22 of the holding finger 20, further forms an undercut 28 of a first type, which acts against an axial pull-out direction, i.e. along the axis of rotation 8.

(19) The projecting section 22 of the holding finger also forms an undercut 30 of a second type, which counteracts a rotation of the cutting tip 14 relative to the shank 12 in the direction of rotation 26.

(20) The cutting tip 14 is provided with a locking projection 32, which comprises a torque transmission counter-geometry 34. This is oriented against the direction of rotation 26.

(21) Corresponding to the torque transmission geometry 24, the torque transmission counter-geometry 34 consists of a flat torque transmission countersurface 34a, which has a surface normal that is oriented substantially in circumferential direction, and a curved torque transmission countersurface 34b (see in particular FIG. 3).

(22) The locking projection 32 is set back relative to an axial front side 36 of the cutting tip along the axis of rotation 8 and thus forms a step.

(23) In the mounted state of the rotary cutting tool 10, the locking projection 32 of the cutting tip 14 engages both in the undercut 28 of the first type and in the undercut 30 of the second type.

(24) The torque transmission counter-geometry 34 furthermore abuts the torque transmission geometry 24.

(25) The cutting tip is secured against unwanted relative rotation with respect to the shank 12 in the direction of rotation 26 by the undercut 30 of the second type. The undercut 30 of the second type thus also counteracts a lifting away of the torque transmission counter-geometry 34 from the torque transmission geometry 24.

(26) Axial withdrawal of the cutting tip 14 from the shank 12 is prevented by the axially effective undercut 28 of the first type.

(27) A securing unit 38 is provided as well, which, in the mounted state, holds the cutting tip 14 on the shank 12.

(28) In the embodiment shown, this securing unit 38 comprises a loading means 40, by means of which the holding finger 20 is pressed axially against the locking projection 32 in the mounted state.

(29) The only thing that matters is the relative relationship of the holding finger 20 to the locking projection 32, so that the locking projection 32, too, is pressed against the holding finger 20 by the loading means 40.

(30) In the first embodiment, the loading means 40 is a clamping screw 42.

(31) The holding finger 20 can be loaded with pressure in the direction of the base body 18 by the clamping screw 42 in such a way that the locking projection 32 is clamped axially between the holding finger 20 and an axial stop surface 44 on the shank 12.

(32) The stop surface 44 represents a bottom surface of the locking geometry 16.

(33) The rotary cutting tool 10 is furthermore provided with coolant channels. The shank 12 comprises a central supply channel 46, which extends substantially along the axis of rotation 8.

(34) The cutting tip 14 is furthermore provided with a connecting pin 48 for the coolant supply, which also extends substantially along the axis of rotation 8. Two outlet lines 50, 52 branch off from this in a forked manner and are depicted in FIGS. 1 and 3 with associated center lines. The coolant can be conducted into a machining zone via the outlet lines 50, 52.

(35) Mounting the cutting tip 14 on the shank 12 proceeds as follows.

(36) First, the cutting tip 14 is brought into a rotational position relative to the shank 12, in which it can be pushed past the projecting section 22 of the holding finger 20 into the locking geometry 16. It is thus moved along the axis of rotation 8 until it abuts the stop surface 44. As a result, the connecting pin 48 is also pushed into an end section of the supply channel 46 and thereby coupled to it in a coolant-conducting manner.

(37) The cutting tip 14 is then rotated relative to the shank 12 against the direction of rotation 26 until the torque transmission geometry 24 and the torque transmission counter-geometry 34 abut one another.

(38) This also causes the locking projection 32 to engage with the undercut 28 of the first type and the undercut 30 of the second type.

(39) The clamping screw 42 is then tightened so that the holding finger 20 deforms elastically in the direction of the base body 18. As a result, the holding finger 20 clamps the locking projection 32 against the stop surface 44.

(40) The cutting tip 14 is thus reliably held on the shank 12. The outlet lines 50, 52 can now also be supplied with coolant via the supply channel 46 in the shank 12.

(41) To remove the cutting tip 14 from the shank 12 again, the described mounting steps need only be carried out in reverse order and with reverse directions of movement.

(42) FIGS. 4 to 7 show a second embodiment of the rotary cutting tool 10.

(43) Only the differences to the first embodiment will be discussed. The same or corresponding components are therefore provided with the same reference signs.

(44) As in the first embodiment, the rotary cutting tool 10 according to the second embodiment, too, is provided with a securing unit 38 which comprises loading means 40.

(45) However, the loading means 40 is now a clamping disc 54.

(46) This is a separate component from the shank 12 and the cutting tip 14.

(47) In the mounted state of the rotary cutting tool 10, the clamping disc 54 is disposed between the cutting tip 14 and the shank 12. It is positioned on a side of the cutting tip 14 facing away from the holding finger 20.

(48) In other words, the clamping disc 54 abuts the stop surface 44 of the shank 12 on the one hand, and an end surface 56 of the cutting tip 14 on the clamped side on the other hand.

(49) The clamping disc 54 comprises a first support geometry 58 which, in the mounted state, abuts the torque transmission geometry 24. The clamping disc 54 is thus positioned on the shank 12 in the direction of rotation 26 via the first support geometry 58. In the embodiment shown, both the torque transmission geometry 24 and the first support geometry 58 are composed of a curved surface section and a flat surface section.

(50) The clamping disc 54 further comprises a second support geometry 60 which, in the mounted state, abuts the torque transmission counter-geometry 34 of the cutting tip 14. The second support geometry 60 therefore helps to position the cutting tip 14 relative to the clamping disc 54 and thus overall to position the cutting tip 14 relative to the shank 12.

(51) In the embodiment shown, the second support geometry 60 comprises a substantially flat support surface. The torque transmission counter-geometry 34 also comprises a substantially flat torque transmission countersurface.

(52) Between the support geometries 58, 60 there is a support region, which supports the torque introduced by the shank 12 into the cutting tip 14. This is also the case for torques that are oriented in the opposite direction.

(53) The clamping disc 54 presses the holding finger 20 axially against the locking projection 32. Once again, the only thing that matters is the interaction between the holding finger 20 and the locking projection 32, so that the locking projection 32 is also axially pressed against the holding finger 20.

(54) The axial thickness of the clamping disc 54 in particular is dimensioned such that this pressing occurs.

(55) The clamping disc 54 furthermore has a certain degree of elasticity. Compressing it between the cutting tip 14 and the shank 12 produces the force by means of which the holding finger 20 and the locking projection 32 are pressed against one another as an elastic reaction force.

(56) The mounting of the cutting tip 14 on the shank 12 is essentially the same as in the first embodiment. The only difference is that, in a preceding step, i.e. before the cutting tip 14 is mounted on the shank 12, the clamping disc 54 is placed against the stop surface 44 and oriented in the direction of rotation 26 by placing the first support geometry 58 against the torque transmission geometry 24.

(57) Of course, when mounting the rotary cutting tool 10 according to the second embodiment, there is also no tightening of the clamping screw 42.

(58) In the rotary cutting tool 10 according to the second embodiment, it is also possible to use the same combination of shank 12 and cutting tip 14 with different clamping discs 54.

(59) The different clamping discs 54 can be used to compensate for wear that occurs over the service life of the rotary cutting tool 10. Alternatively or additionally, the compressive force that exists between the holding finger 20 and the locking projection 32 can be influenced in a targeted manner by using different clamping discs 54.

(60) FIGS. 8 and 9 show a third embodiment of the rotary cutting tool 10. Again, only the differences to the two aforementioned embodiments will be discussed. Consequently, the same or corresponding components are again provided with the same reference signs.

(61) In the rotary cutting tool 10 according to the third embodiment, the securing unit 38 comprises a securing pin 62.

(62) Said pin comprises a pin shank 64 and an axially adjoining pin head 66.

(63) The securing pin 62 extends substantially axially along the axis of rotation 8.

(64) The securing pin 62 furthermore consists of two securing pin halves 62a, 62b. These are separated from one another by an axial gap 62c, which extends both through the pin shank 64 and through the pin head 66. The securing pin halves 62a, 62b are thus elastically deformable in a radial direction with respect to the axis of rotation 8.

(65) The pin shank 64, including the axial gap 62c, has a substantially circular cross-section.

(66) The pin head 66, on the other hand, has a substantially oval cross-section, the axial gap 62c again being included. The cross-section of the pin head 66 is configured such that it projects radially over the pin shank 64 on all sides.

(67) An opening 68, which is assigned to the securing pin 62, is furthermore provided on the cutting tip 14. This, too, extends substantially along the axis of rotation 8.

(68) The opening 68 comprises a feed section 70 and an end section 72. The end section 72 axially adjoins the feed section 70 in the direction toward the front side 36 of the cutting tip 14.

(69) The feed section 70 has a substantially oval cross-section, which is configured such that the pin head 66 can be pushed through the feed section 70.

(70) An axial length of the feed section 70 furthermore substantially corresponds to an axial length of the pin shank 64.

(71) At least in sections, a cross-section of the end section 72 has a cross-section that is enlarged relative to the feed section 70.

(72) The axial length of the end section 72 is substantially equal to an axial length of the pin head 66 or greater.

(73) Therefore, at least in those regions in which the cross-section of the end section 72 radially exceeds the cross-section of the feed section 70, the end section 72 forms an undercut 74 of a third type relative to the feed section 70, which acts along the axis of rotation 8, i.e. axially.

(74) In a mounted state of the rotary cutting tool 10, the securing pin 62 engages in the opening 68. In doing so, the pin head 66 engages behind the undercut 74 of the third type formed by the end section 72 and thus secures the cutting tip 14 on the shank 12.

(75) Mounting the cutting tip 14 on the shank 12 proceeds as follows.

(76) The securing pin 62 and the cutting tip 14 are first brought into a second rotational position, in which the cross-section of the pin head 66 and the cross-section of the feed section 70 are substantially congruent.

(77) In this second rotational position, the securing pin 62 is inserted along the axis of rotation 8 through the feed section 70 into the opening 68. The cutting tip 14 then abuts the stop surface 44 of the shank 12.

(78) The cutting tip 14 is then moved into a first rotational position by rotating it against the direction of rotation 26 relative to the shank 12. On the one hand, this brings the torque transmission geometry 24 into abutment with the torque transmission counter-geometry 34. On the other hand, the pin head 66 is rotated within the end section 72 such that it engages in the undercut 74 of the third type.

(79) In addition, a peripheral surface of the pin head 66 is elastically placed against a peripheral surface of the end section 72 of the opening 68, for which the two securing pin halves 62a, 62b are elastically deformed radially inward. The cutting tip 14 and the securing pin 62 are thus also coupled in a friction-locking manner.

(80) Overall therefore, the cutting tip 14 is reliably held on the shank 12.

(81) The above embodiments of the rotary cutting tool 10 have been explained with the aid of a single locking geometry 16, which cooperates with a single locking projection 32 of the cutting tip 14. However, it goes without saying that, in all of the discussed embodiments, two such locking geometries 16 are provided, which are positioned diametrically opposite one another on the shank 12. The cutting tip 14 accordingly also comprises two associated locking projections 32.