ROTARY TOOL, PARTICULARLY A DRILL, AND A CUTTING HEAD FOR SUCH A ROTARY TOOL

Abstract

A rotary tool comprising two coupling parts, namely a carrier and a cutting head in a front end surface. The carrier comprises a pin receptacle into which a coupling pin of the cutting head is inserted. In order to prevent pulling-out in an axial direction, stop surfaces are provided on the pin receptacle and on the coupling pin, said stop surfaces being effective in an axial direction. For a design that is as simple as possible, in particular with regard to grinding, each stop surface of the coupling pin is adjoined by a lateral surface which freely tapers off in the direction toward the end surface as viewed in the axial direction. In particular, the lateral surface constitutes a torque surface.

Claims

1. A rotary tool, in particular a drill, which extends in an axial direction along an axis of rotation and comprises two coupling parts, namely a carrier and a cutting head with a front end surface, and the cutting head is interchangeably attached to the carrier, wherein the carrier comprises on its end surface fastening webs by means of which a pin receptacle is delimited, a coupling pin of the cutting head is inserted into the pin receptacle by rotating the cutting head relative to the carrier, shell surfaces corresponding to one another are formed on the coupling pin and on the fastening webs for radial centering and for transmitting a radial clamping force, torque surfaces corresponding to one another are formed on the cutting head and on the carrier for transmitting a torque, in order to prevent pulling-out in an axial direction, stop surfaces are formed on the pin receptacle and on the coupling pin, the stop surfaces being effective in an axial direction, wherein each stop surface of the coupling pin is adjoined by a lateral surface which freely tapers off in the direction toward the end surface, as viewed in the axial direction.

2. The rotary tool according to claim 1, wherein the stop surfaces form upper boundary surfaces of the coupling pin.

3. The rotary tool according to claim 1, wherein the respective lateral surface is formed via grinding as a flat, ground surface.

4. The rotary tool according to claim 1, wherein the respective lateral surface constitutes a torque surface that extends up to the outermost circumference of the cutting head.

5. The rotary tool according to claim 1, wherein a torque surface is formed which adjoins the stop surface and which extends up to the outermost circumference of the cutting head.

6. The rotary tool according to claim 1, wherein the lateral surface is spanned by a transverse direction and by a longitudinal direction, wherein the transverse direction extends orthogonally to the axial direction and the longitudinal direction is inclined by an inclination angle with respect to the axial direction.

7. The rotary tool according to claim 6, wherein the inclination angle is in the range between 10 and 25.

8. The rotary tool according to claim 1, wherein when viewed in the axial direction, the stop surface does not protrude beyond the end surface.

9. The rotary tool according to claim 1, wherein when viewed in the axial direction, the stop surface protrudes beyond the end surface.

10. The rotary tool according to claim 6, wherein in a projection in the transverse direction, the cutting head comprises a trapezoid rear surface which is adjoined downwardly in the axial direction by the coupling pin, which protrudes on both sides beyond the trapezoid rear surface in the radial direction.

11. The rotary tool according to claim 6, wherein the lateral surface tapers off into a flute.

12. The rotary tool according to claim 11, wherein the flute ends opposite the lateral surface at a circumferential minor cutting edge, wherein the minor cutting edge lies behind a plane spanned by the lateral surface so that the plane does not touch the cutting head in the region of the minor cutting edge.

13. The rotary tool according to claim 12, wherein the minor cutting edge is inclined at a flute angle and the inclination angle substantially corresponds to the flute angle so that the minor cutting edge extends parallel to the longitudinal direction, or in that the inclination angle is smaller than the flute angle, in particular approximately 5-15 smaller.

14. The rotary tool according to claim 1, wherein the shell surfaces extend in parallel to the axial direction.

15. The rotary tool according to claim 1, wherein the coupling pin is in the shape of a circular disk, preferably with opposing recesses for each flute.

16. The rotary tool according to claim 1, wherein the coupling pin is designed as a central segment of the cutting head, which central segment is adjoined in the radial direction by the torque surface.

17. The rotary tool according to claim 1, wherein the coupling pin comprises at least one pair of clamping segments opposing one another on the pin, and the pin receptacle comprises at least one pair of clamping segments opposing one another, wherein each clamping segment respectively comprises several clamping surfaces which respectively extend along a circular arc in a cross section as viewed orthogonally to the axial direction, wherein the diameter of the clamping surfaces that succeed one another in a predefined direction of rotation increases.

18. The rotary tool according to claim 1, wherein the shell surfaces are designed to transmit a radial clamping force, and for this purpose several flat partial surfaces which are respectively used to transmit the clamping force are formed on the coupling pin.

19. A cutting head for a rotary tool, in particular a drill, which cutting head extends in an axial direction along an axis of rotation, comprises a front end surface and a coupling pin for fastening in a pin receptacle of a carrier, wherein the coupling pin comprises shell surfaces for radial centering and for transmitting a radial clamping force as well as stop surfaces effective in an axial direction in order to prevent pulling-out in an axial direction, wherein each stop surface is adjoined by a lateral surface which freely tapers off in the direction toward the end surface, as viewed in the axial direction.

20. The cutting head according to claim 19, wherein the clamping pin comprises a pair of clamping segments opposite one another, wherein the clamping segments respectively comprise several successive clamping surfaces which respectively extend along a circular arc in a cross section as viewed orthogonally to the axial direction, wherein the diameter of the clamping surfaces that succeed one another in a predefined direction of rotation increases.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Exemplary embodiments of the invention are explained in greater detail on the basis of the figures. These show, partially in simplified illustrations:

[0039] FIGS. 1A, 1B are lateral views in section of a modular rotary tool designed as a drill in accordance with a first variant with a cutting edge completely screwed into a carrier (FIG. 1A), and with an inserted cutting head which is still to be clamped into the carrier by turning (FIG. 1B),

[0040] FIGS. 2A, 2B is a lateral view (FIG. 2A) of the carrier according to FIGS. 1A, 1B and a sectional view (FIG. 2B) along the section line II-II in FIG. 2A,

[0041] FIGS. 3A, 3B, 3C are different views of the cutting head according to FIGS. 1A, 1B,

[0042] FIG. 4 is a perspective illustration of the carrier according to FIGS. 1A, 1B,

[0043] FIGS. 5A, 5B, 5C are various illustrations of a second embodiment of the modular rotary tool with the cutting head inserted (FIG. 5A) as well as exploded views (FIGS. 5B, 5C),and

[0044] FIGS. 6A to 6C are various views of the cutting head according to the second embodiment, while

[0045] FIG. 7 is a perspective view of the carrier of the second embodiment.

[0046] Parts that function in the same manner have the same reference numbers in the figures.

DETAILED DESCRIPTION

[0047] The rotary tool 2 illustrated in the figures is designed as a modular drilling tool. It extends in an axial direction 4 along an axis of rotation 6. The rotary tool 2 rotates about the axis of rotation 6 during normal operation in the direction of rotation 8, which at the same time defines a circumferential direction.

[0048] The rotary tool 2 is composed of a carrier 10 and a cutting head 12 that can be interchangeably attached thereto. The cutting head 12 comprises major cutting edges (not described in more detail here) which are usually connected to one another in the center at a drill face via cross-cutting edges, and which extend radially outwardly. Counter to the direction of rotation 8, the major cutting edges are adjoined by major free spaces on the end surface which are part of a front end surface 13 of the cutting head 12. The end surface 13 is typically constituted by the major free spaces and the surface regions in the center of the cutting head, where the major cutting edges are generally connected to one another via cross-cutting edges. On its circumferential side, the cutting head 12 comprises a rear portion 14 which is interrupted by opposing flutes 16. The flutes preferably start at the cutting head 12 and transition into the carrier 10. In the present working embodiment, the flutes 16 extend approximately helically. The carrier 10 has a grooved shaft region at which minor cutting edges 17 typically continue, which minor cutting edges extend along the flutes 16 and start at the cutting head 12. The grooved shaft region of the carrier 10 is, in usual manner, additionally adjoined by a non-grooved clamping segment with which the rotary tool 2 is clamped in a machine tool.

[0049] In the following, corresponding elements on the carrier 10 are designated with the letter a and corresponding elements on the cutting head 12 are designated with the letter b.

[0050] The carrier 10 comprises on its end surface two approximately diagonally opposing fastening webs 18, which are interrupted by the flutes 16. In the present working embodiment, the fastening webs 18 are respectively designed to be approximately stepped, wherein the bottom step surface constitutes a front support surface 22a on which the cutting head 12 rests with a head support surface 22b. The front support surface 22a as well as the head support surface 22b are each respectively adjoined by a torque surface 30a,b, each of which respectively extends up to the outer circumference, i.e. up to the rear portion 14. An upper step surface of the fastening web 18 constitutes a free end surface of the carrier 10 which thus is not covered by the cutting head 12. In the present working embodiment, coolant channels exit at this free end surface.

[0051] The torque surface 30a is generally spanned by a transverse direction 34 and a longitudinal direction 36. The transverse direction 34 is oriented orthogonally to the axial direction 4 and, in the first example embodiment according to FIGS. 1A and 1B, the longitudinal direction 36 is oriented at an inclination angle a with respect to the longitudinal direction 36.

[0052] For the clamping attachment of the cutting head 12 in the carrier 10, the cutting head 12 has a clamping or coupling pin 38 that corresponds to the pin receptacle 20 and that, in the first example embodiment of FIGS. 1 to 4, adjoins the head support surfaces 22b downward in the axial direction. The coupling pin 38 respectively has on its shell side clamping segments 32b that are arranged oppositely in pairs and interact with corresponding clamping segments 32a of the pin receptacle 20. A press fit is respectively produced between these clamping segments 32a,b that are associated with one another.

[0053] In the first example embodiment, the coupling pin 38 is overall designed like a circular disk with circular segment-like recesses 40, as can be seen in particular in FIG. 3B. As can furthermore be seen in particular in FIGS. 3A to 3C, the coupling pin 38 is also adjoined in the axial direction by a lead-in or centering pin 42 which, however, does not produce any press fit with the carrier in the inserted condition.

[0054] In order to prevent a pulling-out in the axial direction, stop surfaces 44a,b that correspond to one another and that in particular constitute an upper boundary surface of the coupling pin 38 are formed on the pin receptacle 20 and on the coupling pin 38. In particular, they travel horizontally, i.e. orthogonal to the axial direction. As an alternative to a precise horizontal orientation, they can be slightly inclined, for example at an angle of up to 30.

[0055] It is now of special note that the stop surfaces 44b of the coupling pin 38 are exposed in the manner of an uncovering. For this purpose, the stop surface 44b is adjoinedpreferably by forming a curveby a lateral surface 46 that is preferably designed (particularly) as a planar ground surface. This lateral surface 46 extends in the direction toward the end surface 13 and tapers off freely at its end. In a top view, as viewed in the axial direction (cf. for example FIG. 3C), the lateral surface 46 is therefore not covered by the end surface 13. In the first exemplary embodiment of FIGS. 1 to 4, the lateral surface 46 is also adjoined in the direction toward the end surface 13 by an additional ground surface that is oriented in the direction opposite the lateral surface 46. In the present example embodiment, a bend is formed between the two surfaces, which bend is approximately at the level of the free boundary surface of the fastening webs 18 on the end surface side. This additional ground surface extends up to the end surface 13.

[0056] In the region of the cross-cutting edge, what is known as a point thinning 47 is generally also provided; this is illustrated, for example, in FIG. 3A as a central surface region next to the flute 16 and above the torque surface 30b. This point thinning 47 is presently not associated with the end surface 13.

[0057] In the embodiment of FIGS. 1 to 4, the lateral surface 46 simultaneously also constitutes the torque surface 30b.

[0058] Corresponding to the stop surface 44b, the carrier 10 comprises a stop surface 44a on the carrier side, which stop surface is designed as a stepped overhang (cf. FIGS. 1A, 2A and 4). In an angular region covered by the front support surface 22a, the pin receptacle 20 in particular comprises inner shell regions that taper off upwardly without an overhang toward the front support surfaces 22a. In contrast thereto, the overhang with the stop surfaces 44a is formed in the angular region of the fastening webs 18 that adjoins the front support surfaces 22a. These also extend correspondingly to the stop surfaces 44b, and in particular in a direction orthogonal to the axial direction 4.

[0059] When viewed in a projection in the transverse direction 34, the lateral surfaces 46 being oriented at an inclination angle a results overall in a lateral view of the cutting head 12 as illustrated in FIG. 3C. Here, a trapezoidal rear surface 48 of the rear portion 14 can be well appreciated, wherein that surface tapers off in a direction toward the coupling pin 38.

[0060] As can be well appreciated from this lateral illustration, the longitudinal direction travels at least largely parallel to the minor cutting edge 17. The minor cutting edge is oriented at a flute angle relative to the axial direction 4, wherein that flute angle thus at least substantially corresponds to the inclination angle .

[0061] Overall, the lateral surface 46 spans a plane E which is oriented such that it tapers off freely into an adjoining flute 16 on the one hand, and furthermore is oriented such that it does not touch or intersect the minor cutting edge 17 adjoining the respective flute 16. This ensures that the opposing minor cutting edge 17 is not damaged during grinding of the lateral surface 46.

[0062] As can already been seen in FIGS. 3A to 3C, each clamping segment 32b of the coupling pin 38 has several clamping surfaces (two in the present working embodiment), indicated at 50b, 52b; these clamping surfaces are separated in particular by a concavely curved transition region 53b, which is curved in the opposite direction of the clamping surfaces 50b, 52b. The clamping surfaces 50b, 52b are respectively partially cylindrical. Each clamping surface 50b, 52b is assigned to an opposite clamping surface 50b, 52b of the coupling pin 38 so that a clamping surface pair is respectively constituted. Of special note, each diameter d1, d2 of such a clamping surface pair is different. The clamping surfaces 50b, 52b themselves constitute partially cylindrical surfaces, thus lying on a circular arc. The diameter d1 is associated with the clamping surfaces 50b and the diameter d2 is associated with the clamping surfaces 52b. When screwing the cutting head 12 into the carrier 10, the cutting head is generally screwed in counter to the conventional drilling direction of the rotation indicated at 8. In doing so, the clamping surfaces 52b initially come to overlap the fastening webs 18, thus constituting leading clamping surfaces during screwing-in. These leading clamping surfaces 52b have a smaller diameter d2 than the trailing clamping surfaces 50b. The difference in diameter between successive clamping surfaces 50b, 52b is preferably in the range of 0.04 mm to 0.1 mm.

[0063] The pin receptacle 20 comprises corresponding partially cylindrical clamping surfaces 50a, 52a with a transition region 53a lying between them.

[0064] In connection with FIGS. 5 to 8, a second embodiment is explained in more detail, wherein mainly the differences relative to the first embodiment are described below. With regard to the same or comparable designs of the individual parts, reference is made to the description of the first example embodiment.

[0065] A first differentiating feature is apparent in that the coupling pin 38 is no longer designed as an in particular disk-shaped element attached downward in the axial direction, but rather constitutes a central segment 54. This means that the coupling pin 38 is generally adjoined in the radial direction by a surface. The surface adjoining in the radial direction in particular constitutes a part of the torque surface 30b. In this case, the coupling pin 38 also comprises an upper, (particularly, once again) at least substantially horizontal stop surface 44b. The latter is adjoined by the lateral surface 46, considered upwardly and in axial direction 4 toward the front side end surface 13. This lateral surface may be, but does not necessarily need to be, a part of the torque surface 30b. In the present example embodiment, the lateral surface 46 is also adjoined in the radial direction by an upper partial segment of the torque surface 30b.

[0066] Another difference relative to the first embodiment can be seen in that the lateral surface 46 extends parallel to the axial direction 4, i.e. its longitudinal direction 36 extends parallel to the axial direction 4. In this embodiment variant, there is basically the possibility of also designing the longitudinal direction 36 to be inclined in a similar manner as in the first embodiment variant. The bottom side of the coupling pin 38 presently lies in a common plane together with a support surface of the cutting head 12, with which it rests at the floor in the pin receptacle 20.

[0067] The torque surfaces 30a,b therefore extend in an axial direction over the entire axial length of the pin receptacle 20. Accordingly, the fastening webs 18 in the second embodiment are also not formed like steps. The torque surface 30a constitutes a continuous, flat surface. There is basically also the possibility that this can be designed to be diagonally inclinedsimilar to the lateral surface 46 described previously.

[0068] In order to form the stop surface 44a on the carrier, at the end of the fastening web 18 a radially inwardly oriented overhang is formed which thus covers to this extent a corresponding clamping segment 32a on the carrier 10.

[0069] As can be seen in particular in the top view according to FIG. 6C, in this embodiment, the stop surface 44b protrudes from the end surface 13, thus protruding beyond it in the radial direction.