Rotary cutting tool and tool assembly

Abstract

A rotary cutting tool comprises a tool body having an axis of rotation (L) and a cylindrical shank, which comprises at least one locking groove via which the cutting tool can be axially locked in a tool holder. The locking groove has an axial groove, which extends from an axial end on the receiving side in axial direction (A) to an axial stop, and a circumferential groove, which is laterally adjacent to the axial groove and extends away from the axial stop and the axial groove in circumferential direction (U) toward a rotation stop. The circumferential groove comprises a first end face and a second end face opposite to said first end face, both of which extend in a plane that is perpendicular to the axis of rotation (L). A tool assembly having such a rotary cutting tool and a tool holder having a cylindrical tool receptacle for the cutting tool is provided as well.

Claims

1. A rotary cutting tool including a tool body comprising a central longitudinal axis (L) which forms an axis of rotation (L) of the cutting tool, wherein, at one axial end, the tool body comprises a cylindrical shank having at least one locking groove via which the cutting tool can be axially locked in a tool holder, wherein the locking groove has an axial groove, which extends from an axial end on a receiving side in axial direction (A) to an axial stop, and a circumferential groove, which is laterally adjacent to the axial groove and extends away from the axial stop and the axial groove in circumferential direction (U) toward a rotation stop, wherein the circumferential groove comprises a first end face and a second end face opposite to said first end face, wherein both the first and the second end face extend in a plane that is perpendicular to the axis of rotation (L), and wherein, in a sectional plane that is perpendicular to the axis of rotation (L), the axial groove has a lenticular cross-section with a radially outer section which is formed by an envelope on an outer circumference of the shank and a radially inner section which is formed by a circular arc.

2. The cutting tool according to claim 1, wherein, in a sectional plane in which the axis of rotation (L) is located, the circumferential groove has a rectangular cross-section.

3. The cutting tool according to claim 1, wherein a maximum radial height (h.sub.1) of the lenticular cross-section is less than half of the radius (r.sub.1) of the circular arc of the radially inner section.

4. The cutting tool according to claim 1, wherein the rotation stop delimits a region of the circumferential groove.

5. The cutting tool according to claim 1, wherein the cutting tool has a defined cutting direction (U) which corresponds to a direction of rotation (U) about the axis of rotation (L), wherein the circumferential groove extends away from the axial groove in the cutting direction (U).

6. The cutting tool according to claim 1, wherein the cutting tool comprises two to five corresponding locking grooves, which are spaced apart from one another in circumferential direction (U).

7. The cutting tool of claim 6, wherein the cutting tool comprises three to four locking groove.

8. The cutting tool of claim 6, wherein the locking grooves exhibit rotational symmetry.

9. A tool assembly comprising a rotary cutting tool according to claim 1, and a tool holder having a cylindrical tool receptacle for the cutting tool, wherein the tool holder has a common axis of rotation (L) with the cutting tool, wherein the tool receptacle comprises at least one locking element which is associated with the at least one locking groove, wherein the tool assembly has a free position, in which the at least one locking element is disposed in the axial groove of one of the at least one locking grooves such that the cutting tool can be pulled out of the tool receptacle in axial direction (A), and a locked position, in which the corresponding locking element is disposed in the circumferential groove of the corresponding locking groove such that the cutting tool cannot be pulled out in axial direction (A).

10. The tool assembly according to claim 9, wherein the at least one locking element comprises a first abutment surface and a second abutment surface disposed opposite to said first abutment surface, wherein both the first and the second abutment surface extend in a plane that is perpendicular to the axis of rotation (L).

11. The tool assembly according to claim 9, wherein, in a sectional plane that is perpendicular to the axis of rotation (L), the at least one locking element has a lenticular cross-section with a radially outer section which is formed by the inner circumference of the tool receptacle and a radially inner section which is formed by a circular arc.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages and features result from the following description and from the accompanying drawings. The figures show:

(2) FIG. 1 in a schematic sectional view, a tool assembly according to the invention having a rotary cutting tool according to the invention and a tool holder,

(3) FIG. 2 in a bottom view looking in axial direction A, the rotary cutting tool of FIG. 1 showing an axial end on the receiving side of the rotary cutting tool,

(4) FIG. 3 in a lateral view, the axial end on the receiving side of the rotary cutting tool of FIG. 2,

(5) FIG. 4 in a plan view looking against the axial direction A, a section of the tool holder of FIG. 1 having a tool receptacle, and

(6) FIG. 5 in a lateral view, the section of the tool holder having the tool receptacle of FIG. 4, wherein hidden edges are indicated with dashed lines.

(7) FIG. 1 shows a longitudinal section of a tool assembly 10 having a tool holder 12 and a rotary cutting tool 14, which is inserted in said tool holder 12.

(8) The cutting tool 14 has a tool body 15, which extends along a longitudinal axis L.

(9) An axial direction A, which corresponds to a direction parallel to the longitudinal axis L, is identified in FIGS. 1 to 5.

(10) Furthermore, a radial direction R, which corresponds to a direction perpendicular to the longitudinal axis L, is identified in FIGS. 1, 3 and 5.

(11) The longitudinal axis L also forms a common axis of rotation of the tool holder 12 and the cutting tool 14.

(12) The cutting tool 14 is provided for machining in a defined direction of rotation, which in this case corresponds to the circumferential direction U in clockwise direction. This means that, during operation, the cutting tool 14 is driven in circumferential direction U so as to exert a cutting force on the workpiece.

(13) In the present design example, the cutting tool 14 is a twist drill having a workpiece-side head 16 adjoined by helical flutes 18 and a shank 20 having an axial end 22 on the receiver side.

(14) In principle, the cutting tool 14 can be any rotary cutting tool having a corresponding shank 20, for example a round drill, profile drill, tap drill, spot facer or milling cutter.

(15) The tool holder 12 has a tool receptacle 24, which forms a chuck for the shank 20 of the cutting tool 14. The dashed region in FIG. 1 merely identifies the section X of the tool holder 12 shown in FIG. 5, in which the actual geometry of the tool receptacle 24 is shown.

(16) The chuck is a shrink fit chuck or a hydraulic chuck, for example.

(17) In order to prevent axial migration of the cutting tool 14 out of the tool holder 12 during operation, the tool assembly 10 comprises axial securing means 26, which are formed by a locking groove 28 (see FIGS. 2 and 3) in the shank 20 and corresponding locking elements 30 (see FIGS. 4 and 5) of the tool receptacle 24.

(18) In the embodiment shown, the tool assembly 10 further comprises a securing element 32 in the form of a securing ring, which can be screwed to the tool holder 12 and additionally secures the cutting tool 14 in the tool holder 12.

(19) However, such a securing element 32 is optional and can be omitted in an alternative embodiment.

(20) Furthermore, the securing element 32 can in principle have any desired configuration and be coupled to the tool holder 12 in any way.

(21) The structure and functioning of the axial securing means 26 are described in the following with the aid of FIGS. 2 to 5, in which hidden edges are indicated with dashed lines.

(22) The shank 20 has the basic shape of a circular cylinder having a diameter d1 (see FIG. 2) and, in the present design example, has three locking grooves 28 which extend radially inward from the cylindrical outer casing.

(23) The three locking grooves 28 are disposed rotationally symmetrically to one another at a respective angle α of 120°.

(24) In principle, the shank 20 can comprise any number of locking grooves 28, in particular one to five locking grooves 28, wherein the number of locking grooves 28 substantially depends on the diameter d1 and thus on the available outer circumference of the shank 20.

(25) Three or four locking grooves 28 are advantageous for a shank 20 having a diameter d1 of 20 mm to 40 mm.

(26) The locking grooves 28 can furthermore be arranged as desired over the outer circumference of the shank 20; however, a rotationally symmetrical arrangement is preferred.

(27) The locking grooves 28 are configured identically. The configuration of the locking grooves 28 is therefore explained in the following using a locking groove 28 as an example.

(28) Of course, in an alternative embodiment, the locking grooves 28 can be configured differently from one another.

(29) The locking groove 28 consists of an axial groove 34 (see FIG. 3) and a circumferential groove 36, which directly adjoins the axial groove 34 in circumferential direction U.

(30) The axial groove 34 extends from the axial end 22 in axial direction A to an axial stop 38 (formed by a radial surface), whereas, adjoining the axial stop 38, the circumferential groove 36 extends in circumferential direction U away from the axial groove 34 to a rotation stop 40.

(31) In a lateral view, the locking groove 28 thus has an “L” shape.

(32) In the sectional plane perpendicular to the axis of rotation L (see FIG. 2), the axial groove 34 has a lenticular cross-section 42 with a radially outer section 44 and a radially inner section 46.

(33) The radially outer section 44 is formed by a section of the envelope of the cylindrical shank 20 and is thus open.

(34) The radially inner section 46 is a circular arc having a radius r.sub.1.

(35) The radius r.sub.1 is preferably greater than the maximum radial height h.sub.1 of the lenticular cross-section 42.

(36) In an alternative embodiment, the axial groove 34 can in principle have any cross-section 42, as long as it does not prevent the insertion of a locking element 30 in axial direction A.

(37) The circumferential groove 36 comprises a first end face 48 and a second end face 50, which are opposite to one another in axial direction A and both extend in a plane that is perpendicular to the axis of rotation L.

(38) In a sectional plane in which the axis of rotation L is located, the circumferential groove 36 has a rectangular cross-section 52 (see FIG. 3), wherein the radial inner side 54 which forms the base of the circumferential groove 36 extends in axial direction A, whereas the opposite radial outer side is formed by a section of the envelope of the cylindrical shank 20 and is thus open.

(39) In circumferential direction U from the axial groove 34 to the rotation stop 40, the circumferential groove 36 has a constant depth h.sub.2 which corresponds to the maximum radial height h.sub.1 of the lenticular cross-section 42.

(40) At the rotation stop 40, starting from the axial groove 34, the radial inner side 54 extends in a plane which is perpendicular to the axis of rotation L first along a cylinder having the radius R.sub.G from the longitudinal axis A and then in a curve having the radius r.sub.1 radially outward to the envelope of the cylindrical shank 20, as a result of which, in a plane which is perpendicular to the axis of rotation L, the region 56 of the circumferential groove 36 adjacent to the rotation stop 40 has a cross-section which corresponds to half of the lenticular cross-section 42 that adjoins the circumferential groove 36 in circumferential direction U. In the view of FIG. 2, in simplified terms, it looks as if this half of the cross-section 42 has simply been pushed a little further clockwise to the end of the circumferential groove.

(41) In an alternative embodiment, the circumferential groove 36 can in principle have any cross-section 52, as long as the first and the second end face 48, 50 extend parallel to one another and perpendicular to the axis of rotation L.

(42) Like the shank 20, the tool receptacle 24 has the shape of a circular cylinder having a diameter d2 (see FIG. 4) and, in the present design example, has three locking elements 30 which extend radially inward from the cylindrical outer casing.

(43) The diameter d2 of the tool receptacle 24 corresponds to the diameter d1 of the shank 20, so that the cutting tool 14 is reliably fixed in the tool holder 12.

(44) In the case of a shrink fit chuck, for example, the components are designed such that there is play at the corresponding joining temperatures when joining and a press fit when the components are at the same temperature.

(45) Of course, in an alternative embodiment, the diameter d2 of the tool receptacle 24 can be greater than the diameter d1 of the shank 20, so that the shank 20 can be inserted into the tool receptacle 24 by hand with minimal play, and thus without tools, even when the components have the same temperature.

(46) Like the locking grooves 28, the three locking elements 30 are disposed rotationally symmetrically to one another at a respective angle α of 120°.

(47) The tool receptacle 24 can in principle comprise any number of locking elements 30, however no more than the number of locking grooves 28 provided in the shank 20.

(48) The tool receptacle 24 preferably comprises a number of locking elements 30 that corresponds to the number of locking grooves 28 in the shank 20.

(49) In all embodiments the locking elements 30 are disposed complementarily to the locking grooves 28 so that, when the shank 20 is inserted into the tool receptacle 24 against the axial direction A, a respective locking element 30 can be pushed into a respective locking groove 28.

(50) The locking elements 30 are configured identically. The configuration of the locking elements 30 is therefore explained in the following using a locking element 30 as an example.

(51) Of course, in an alternative embodiment, the locking elements 30 can be configured differently from one another, in particular if the corresponding locking grooves 28 are configured differently too. This may be provided, for example, to align the cutting tool 14 in a specific position in the tool holder 12.

(52) The locking element 30 comprises a first abutment surface 58 and a second abutment surface 60, which are disposed opposite to one another in axial direction A and both extend in a plane that is perpendicular to the axis of rotation L.

(53) In the sectional plane perpendicular to the axis of rotation L, the locking element 30 has a lenticular cross-section 62 (see FIG. 4) with a radially outer section 64 and a radially inner section 66.

(54) The radially outer section 64 of the locking element 30 is formed by a section of the envelope of the cylindrical tool receptacle 24.

(55) The radially inner section 66 of the locking element 30 is a circular arc having a radius r.sub.2.

(56) The radius r.sub.2 of the radially inner section 66 of the locking element 30 corresponds to the radius r.sub.1 of the radially inner section 46 of the axial groove 34.

(57) As a result, the locking element 30 is complementary to the axial groove 34; however, the locking element only has an axial height t.sub.2 that corresponds to the axial height t.sub.1 of the circumferential groove 36.

(58) In an alternative embodiment, the locking element 30 can in principle have any cross-section 62, as long as it does not prevent the insertion of the locking element 30 into one of the axial grooves 34 in axial direction A.

(59) In a sectional plane in which the axis of rotation L is located, the locking element 30 has a rectangular cross-section 68, which is only shown indirectly in the lateral view in FIG. 5 due to the perspective onto the locking elements 30. The radial inner side 70 of the locking element 30 extends in axial direction A between the first abutment surface 58 and the second abutment surface 60, whereas the opposite radial outer side is formed by a section of the envelope of the cylindrical tool receptacle 24.

(60) In an alternative embodiment, the axial height t.sub.2 can be smaller than the axial height t.sub.1.

(61) As a result, the locking element 30 is also complementary to the circumferential groove 36.

(62) Furthermore, the axial distance t.sub.4 between the first abutment surface 58 and an opposite bottom surface 72 of the tool receptacle 24 is at least as great as the axial distance t.sub.3 between the first end face 48 and the axial end 22 of the shank 20.

(63) All of the locking elements 30 are preferably integrally connected to one another, for example by means of a ring that is introduced into the base body of the tool holder 12 during the production of said tool holder 12.

(64) To couple the cutting tool 14 to the tool holder 12, the shank 20 is inserted into the tool receptacle 24 in such a way that the locking elements 30 are aligned opposite to the axial grooves 34. The shank 20 is then pushed into the tool receptacle 24 against the axial direction until the locking elements 30 abut the axial stops 38 with the second abutment surfaces 60.

(65) This position, in which the locking elements 30 are disposed in the axial grooves 34 and completely outside the circumferential grooves 36, describes a free position of the tool assembly 10. In the free position of the tool assembly 10, the axial securing means 26 are unlocked and the cutting tool 14 can be pulled out of the tool holder 12 in axial direction A.

(66) To lock the axial securing means 26 so that the cutting tool 14 cannot be pulled out of the tool holder 12 in axial direction A, the cutting tool 14 is rotated against the circumferential direction U until the locking elements 30 abut the rotation stops 40. During this rotation, the locking element 30 moves along the stop 38, which continues laterally into the circumferential groove 36 and there forms the end face 50.

(67) This position, in which the locking elements 30 are disposed at least in sections in the circumferential grooves 36, describes a locked position of the tool assembly 10.

(68) The end faces 48, 50 of the circumferential groove 36 form parallel stop surfaces for the abutment surfaces 58, 60 of the locking elements 30.

(69) Due to the complementary geometry of the locking elements 30 and the circumferential grooves 36, in particular in the regions 56 adjacent to the rotation stops 40, the locking elements 30 and the circumferential groove 36 are connected to one another in a form-locking manner in the locked position.

(70) Any possible radial play is prevented in the locked state by the rotation stops 40 and locking elements 60 which taper in a wedge-like manner.

(71) The shank 20 and the tool receptacle 24 are preferably dimensioned such that joining by hand is possible without tools, for example with a corresponding clearance fit. In the case of a shrink fit chuck, the components are designed such that there is play at the corresponding joining temperatures.

(72) To facilitate shifting the tool assembly 10 into the locked position, opposing edges of the locking elements 30 and the circumferential grooves 36 can comprise an insertion geometry such as a chamfer or rounding.

(73) Thus, a tool assembly 10 having a simply configured and at the same time effective axial securing means 26 is provided.

(74) Furthermore, during operation, the locking elements 30 are pressed in circumferential direction U against the rotation stops 40, so that axial migration is reliably prevented.

(75) In the embodiment shown, the axial end 22 of the shank 20 simultaneously forms an axial end of the cutting tool 14.

(76) In an alternative embodiment, the cutting tool 14 can have an axial extension at the axial end 22, which extends away from the shank 20 against the axial direction A. However, the extension is configured such that it does not cover the axial groove 34 in axial direction A, so that the function of the axial securing means 26 is not impaired.

(77) Such an extension can be configured for the torque-transmitting coupling of the cutting tool 14 to the tool holder 12 and, for this purpose, for example have a polygonal cross-section.

(78) The invention is not limited to the shown embodiment. Individual features of one embodiment can in particular be combined as desired with features of other embodiments, in particular independently of the other features of the corresponding embodiments.