TOOL COUPLING BETWEEN TWO COUPLING PARTS, AND COUPLING PART FOR SUCH A TOOL COUPLING

Abstract

A tool coupling used for a clamping connection between two coupling parts, in particular between a cutting head and a carrier of a rotary tool, in particular of a drill. The coupling parts comprise clamping sections, which respectively correspond to one another and which can be clamped against each other by turning counter to a predefined direction of rotation about an axis of rotation so that a press fit is produced. In order to produce a high clamping force and at the same time allow for a simple installation via screwing in, each clamping section comprises several successive clamping surfaces whichwith respect to a cross section viewed orthogonally to the axial directionrespectively travel along a circular arc, wherein the diameter increases for clamping surfaces succeeding one another in the direction of rotation.

Claims

1. A tool coupling between two coupling parts extending in an axial direction, in particular between a cutting head and a carrier of a rotary tool, with a predefined direction of rotation, wherein the first coupling partin particular the cutting headcomprises a clamping pin with a pair of clamping sections that are opposite one another on sides of the pin, and the second coupling partin particular the carriercomprises a pin receptacle with a pair of clamping sections that are opposite one another on sides of the receptacle, and wherein the clamping pin can be clamped by turning it counter to the direction of rotation about an axis of rotation into the pin receptacle so that clamping sections of the clamping pin and the pin receptacle that correspond to one another produce a press fit, wherein each clamping section respectively comprises several successive clamping surfaces, whichin a cross section when viewed orthogonally to the axial directiontravel respectively along a circular arc having a predefined diameter, wherein the diameter of the clamping surfaces that are successive in the direction of rotation increases.

2. The tool coupling according to claim 1, wherein the clamping surfaces are respectively partially cylindrical.

3. The tool coupling according to claim 1, wherein each clamping section comprises more than two, in particular 3 to 5, clamping surfaces with different diameters.

4. The tool coupling according to claim 1, wherein the successive clamping surfaces with different diameters extend over an identical angle.

5. The tool coupling according to claim 1, wherein each clamping surface respectively covers an angle in the range of at least 10 and preferably in the range of 35 to 45.

6. The tool coupling according to claim 1, wherein the difference of the diameters of two successive clamping surfaces is smaller than 0.2 mm and in particular is in the range of 0.04 to 0.1 mm.

7. The tool coupling according to claim 1, wherein a transition region is formed between two successive clamping surfaces, in which transition region the two coupling parts are spaced apart from each other.

8. The tool coupling according to claim 7, wherein each transition region is designed as a curved surface.

9. The tool coupling according to claim 8, wherein the transition regions of the two coupling parts are curved in opposite directions.

10. The tool coupling according to claim 7, wherein the transition region extends over a transition angle in the range of 5 to 30.

11. The tool coupling according to claim 1, wherein the first coupling part is a cutting head, and the second coupling part is a carrier of a modular rotary tool such as a drill or milling cutter.

12. The tool coupling according to claim 11, wherein, on its end surface side, the carrier comprises two opposing fastening webs which form the pin receptacle, wherein there are further formed on the fastening webs torque surfaces against which the cutting head rests with associated torque surfaces in order to transmit torque.

13. A coupling part for a tool coupling, which coupling part extends in an axial direction, in particular a cutting head or a carrier for a carrier tool, with a clamping pin or a pin receptacle, respectively with at least one pair of clamping sections that are opposite each other, wherein each clamping section respectively comprises several successive clamping surfaces whichin a cross section when viewed orthogonal to the axial directionrespectively travel along a circular arc having a predefined diameter, wherein the diameter of the clamping surfaces that are successive in the direction of rotation increases.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] An exemplary embodiment of the invention is explained in greater detail below with reference to the figures. These show, partially in simplified depictions:

[0026] FIG. 1 is a lateral sectional view of a modular rotary tool designed as a drill, with a carrier and a cutting head inserted therein,

[0027] FIGS. 2A, 2B show the cutting head according to FIG. 1 in different views,

[0028] FIG. 3 shows the carrier according to FIG. 1,

[0029] FIG. 4A is a simplified lateral depiction of the rotary tool according to FIG. 1,

[0030] FIG. 4B is a simplified sectional depiction of the rotary tool along the section plane marked in FIG. 4A in the coupling region between a clamping pin and a pin receptacle, with the clamping pin only partially screwed in,

[0031] FIG. 4C is a sectional depiction comparable to FIG. 4B, with the clamping pin completely screwed in, and

[0032] FIG. 4D is an enlarged sectional depiction from FIG. 4C.

[0033] Parts that function in the same manner bear the same reference numerals in the figures.

DETAILED DESCRIPTION

[0034] 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. During normal operation, the rotary tool rotates about the axis of rotation 6 in the direction of rotation 8, which at the same time defines a circumferential direction. The rotary tool is composed of a carrier 10 and a cutting head 12 that is attached thereto so as to be interchangeable. The cutting head 12 comprises major cutting edges (which are not described in more detail) which are usually connected to one another in the center of a drill face via cross-cutting edges, and which extend radially outward. Counter to the direction of rotation 8, major flanks at the end surfaces adjoin the major cutting edges. On its circumferential side, the cutting head 12 comprises a rear surface 14 which is interrupted by opposing flutes 16. The flutes thus already start at the cutting head 12 and transition into the carrier 10. In an example embodiment, the flutes 16 extend approximately helically. The carrier 10 has a grooved shaft section at which, for example, minor cutting edges continue which extend along the flutes 16 and start at the cutting head 12. The grooved shaft section of the carrier 10 is usually also adjoined by a non-grooved clamping section with which the rotary tool 2 is clamped in a machine tool.

[0035] At the same time, the carrier 10 and the cutting head 12 define two coupling parts which are connected to each other via a tool coupling described in detail below.

[0036] To this end, the cutting head 12 comprises a clamping pin 18 which can be inserted in a clamping manner into a corresponding pin receptacle 20 of the carrier 10. In an example embodiment, the clamping pin 18 is designed as a circular disk-like element with likewise circular disk-shaped recesses that oppose one another. The recesses are determined by the flutes 16 which cut the clamping pin 18. In an example embodiment, the clamping pin 18 is furthermore adjoined by a lead-in pin 22 with which the cutting head 12 is pre-centered during inserting.

[0037] On the carrier 10, the pin receptacle 20 is formed by two opposing fastening webs 24 between which the clamping pin 18 is received. In order to insert the cutting head 12 into the carrier 10, the cutting head is initially introduced into the pin receptacle 20 from above in the axial direction, and the cutting head is subsequently turned counter to the direction of rotation 8 by approximately 90 so that it is held in the carrier 10 so as to be clamped and resist being pulled out.

[0038] During operation, the carrier 10 transmits the rotational movementand thus a torqueto the cutting head 12. The cutting head 12 and the carrier 10 comprise several functional surfaces corresponding to one another for transmitting the torque on the one hand and for producing the desired press fit on the other hand. The surfaces corresponding to one another, which come to rest against one another in the inserted state, are designated below with the same reference symbols, wherein the surfaces of the carrier are designated with the letter a, and the surfaces of the cutting head are designated with the letter b.

[0039] As can be seen in FIGS. 1 and 3, the fastening webs 24 are more or less stepped, wherein the transition region of two planar step surfaces forms a torque surface 26a on the carrier side, against which torque surface a corresponding torque surface 26b of the cutting head comes to rest. The torque surfaces 26a,b are generally understood to be surfaces that are designed to transmit the torque during operation.

[0040] For the clamping fastening of the clamping pin 18 in the pin receptacle 20, clamping sections 28a,b are formed which respectively lie opposite one another in pairs. Flutes 16 are respectively formed between the opposite clamping sections 28a,b. As can be seen directly in FIGS. 2A,2B and FIG. 3, each clamping section 28a,b in an example embodiment respectively comprises two clamping surfaces 30a,b and 32a,b, between which a transition region 34a,b is formed. The clamping surfaces 30a,b; 32a,b are partially cylindrical shell surfaces, i.e. outer shell surfaces in the clamping pin 18 and inner shell surfaces in the pin receptacle 20. These shell surfaces extend parallel to the axial direction 4 and, when viewed in cross section relative to this, along a circular arc.

[0041] In order to prevent pulling-out (or pullout) in the axial direction, in an example embodiment, stop surfaces 36a,b corresponding to one another are additionally formed. In the clamping pin 18, these stop surfaces define an upper boundary surface of the clamping pin 18. They travel in particular at least approximately in the horizontal direction, and preferably precisely in the horizontal direction, i.e. orthogonally to the axial direction 4. In the carrier 10, an overhang is formed on each fastening web 24 to form the respective stop surface 36a. In the clamping pin 18, the stop surface 36b is directly adjoined by the torque surface 26b, which is designed in the exemplary embodiment to be diagonally inclined with respect to the axial direction 4. It is in particular designed as a ground surface. It extends in the direction of a front side end surface of the cutting head 12 and, at its end, tapers off freely, i.e., it is not covered at its end by a partial region of the cutting head, in particular not by the front side end surface. This allows for forming the stop surface 36b in a simple manner by grinding.

[0042] The design of the clamping sections 28a,b is explained in more detail below in connection with FIGS. 4A to 4B. For reasons of clarity, substantially only the reference symbols in connection with the clamping pin 18 are specified in the figures.

[0043] In FIGS. 4B to 4D, it can once again be seen that the respective clamping section 28b in the exemplary embodiment comprises two clamping surfaces 30b, 32b, which are separated from each other by a transition region 34b. As a result of the arrangement of the clamping sections 28b in pairs, the clamping surfaces 30b, 32b corresponding to one another are also arranged in pairs opposite one another. The clamping surface pair of the clamping surfaces 30b has a diameter d1, and the clamping surface pair of the clamping surfaces 32b has a diameter d2. The diameter d1 is slightly smaller than the diameter d2. The clamping surfaces 30b are leading clamping surfaces, and the clamping surfaces 32b are trailing or following clamping surfaces. This is understood to mean that the leading clamping surfaces 30b are arranged in a leading position during the screwing-in of the clamping pin 18 counter to the direction of rotation 8.

[0044] As a result of the smaller diameter d1, the clamping surfaces can therefore initially be screwed into the pin receptacle 20 with some play until they reach the clamping surfaces 30a of the pin receptacle 20 that are associated with them. The clamping surfaces 30b, 32b are therefore designed and arranged such that they reach their associated clamping surfaces 30a, 32a of the pin receptacle 20 at the same rotational position of the clamping pin 18 in the pin receptacle 20. The individual associated clamping surfaces 30a,b; 32a,b therefore come to engage with one another at the same time to produce the force fit or press fit. For this purpose, it is in particular provided that the individual clamping surfaces 30b, 32b extend over the same angle . At the same time, the transition region 34b extends over a transition angle . In the exemplary embodiment, the angle is in the range of 30 to 45 and in particular in the range between 35 and 40. At the same time, the transition angle is preferably in the range of 5 to 20 and in particular in the range of approximately 10 to 15. Overall, the respective clamping section 28b extends over an angular range of 2+ and, for example, is in the range between 80 and 110, preferably approximately 95 to 105.

[0045] The clamping surfaces 30a, 32a of the pin receptacle 20 are also designed to correspond to the clamping surfaces 30b, 32b of the clamping pin 18. These clamping surfaces 30a, 32a preferably extend over the same angle as do the clamping surfaces 30b, 32b. The transition angle is also preferably identical or at least similar to that of the clamping pin 18.

[0046] With regard to the desired press fit between the clamping surfaces 28a,b associated with one another, the clamping sections 28b have a slight oversize with respect to the clamping sections 28a of the pin receptacle 20. This means that the clamping surfaces 30a, 32a of the pin receptacle 20 have diameters that are respectively slightly less than the diameters d1, d2 of the clamping pin 18. The oversize is typically a few 1/100 mm.

[0047] As can be seen in particular in FIGS. 4C and 4D, a free space, i.e. a radial play, is formed in the transition region 34a,b between the surface sections corresponding to one another of the clamping pin 18 and the pin receptacle 20. With regard to the production process, the clamping sections 28a,b of the carrier 10 are formed by way of a milling cutter, and of the clamping pin 18 are formed by way of a grinding wheel. As a result of the different diameters d1, d2, the respective tool (grinding wheel or milling cutter) must be shifted somewhat in the radial direction so that the transition region 34a,b is formed. Accordingly, the transition regions 34a,b are defined by curved lines, wherein the radius of curvature respectively corresponds to the radius of the tool used, i.e. of the grinding wheel on the one hand and of the milling cutter on the other hand. These radii are drawn in FIG. 4C as radius r1 for the milling cutter and as radius r2 for the grinding wheel.

[0048] Overall, the design of the clamping sections 28a,b with several partially cylindrical clamping surfaces 30a,b; 32a,b achieves on the one hand an easy screwing of the clamping pin 18 into the pin receptacle 20. Sinceas a result of the differences in diameterthe clamping pin 18 can initially be screwed into the pin receptacle virtually without force, an increased force need only be exerted over a limited angular range to produce the press fit. On the other hand, only a minor rotational movement is required during releasing in order to subsequently further unscrew the cutting head 12, largely without force.

[0049] The partially cylindrical design furthermore achieves the particular advantage that the requirements for the fit and tolerance precision of the two coupling parts 10,12, in particular with regard to a defined final position, are comparatively tolerant since no precise relative rotational positioning of the two coupling parts 10,12 to one another is required. Namely, a certain turning with respect to an intended position does not yet result in an abrupt reduction in the clamping force.

[0050] Furthermore, the partially cylindrical design, i.e. at least the design according to which the clamping surfaces 30a,b; 32a,b extend along circular arcs when viewed in cross section, achieves a largely laminar (surface to surface) contact between the coupling partners so that overall, a very high clamping force is achieved.

[0051] The concept introduced here, with several clamping surfaces running along a circular arc per clamping section, is alternatively also implemented in clamping pins 18 with clamping surfaces diagonally inclined with respect to the axial direction, i.e. for example in a clamping pin 18 designed in the manner of a dovetail.

[0052] The tool coupling has been described in the present document in connection with a rotary tool 2, but is not limited thereto. The design of the tool coupling may in principle also be used for other tools in which two coupling parts are connected to each other in a clamping manner by reciprocal turning about an axis of rotation 6.

[0053] Basically, the possibility also exists of the pin receptacle 20 forming a completely circumferential pin receptacle 20unlike in the example embodiments shownso that the clamping pin 18 is therefore enclosed 360 by the pin receptacle 20. In particular, if such completely enclosed pins are assumed, then more than two successive clamping surfaces 30a,b; 32a,b are provided. In such completely enclosed design variants, measures merely have to be taken to allow for an initial insertion of the clamping pin 18 into the pin receptacle 20.