DRILLING TOOL FOR ROCK

This application claims the priority of German Patent Document No. 10 2008 054 925.8-24, filed Dec. 18, 2008, the disclosure of which is expressly incorporated by reference herein.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a drilling tool for rock.

Drilling tools for rock feature an at least partially hollow drill rod having a flushing channel, a drive-side shank for accommodation in the tool receptacle of a propulsive drilling tool device and an output-side coupling means as well as a drill head having flushing openings and cutting edges made of hard material, which drill head is connected to this in a rotationally secured manner and detachably by means of a catch means.

A drilling tool for rock having an at least partially rotating and percussively loaded drill rod and having a drill head studded with hard material is known from European Patent Document No. EP 1 267 033 A1. The drill rod and the drill head are detachably connected to one another via a coupling means such that they are, to a limited extent, axially mobile with rotary form-locking, and also connected to each other via a catch means, wherein at least one radially projecting rotary lock-in bar is attached on a front end of the drill rod. The rotary lock-in bar in this case engages in at least one rotary lock-in slot of a rotary lock-in surface of a cup-shaped drill head, which slot runs along the tool axis.

The object of the present invention is further improving the known drilling tool and in particular simplifying the assembly and disassembly of the drill head on the drill rod.

According to this, a coupling mechanism has an elastic lock for holding the rotary lock-in bar in the rotary lock-in slot. A reliable connection of the drill head and the drill rod is hereby achieved in a technically simple manner, in particular the drill head and drill rod may be separated again by hand without implements. In addition, the attainment according to the invention can be manufactured very cost-effectively.

The elastic lock is advantageously arranged on the drill rod, whereby additional costs from manufacturing the drill heads are avoided and any additional costs that are incurred for the drill rod have only a negligible impact on the total cost, due to the longer service life of the drill rod.

Alternatively, the elastic lock may also be arranged on the drill head, thereby reducing the noise radiation of the drilling tool. This variant is particularly advantageous for manufacturing in the case of smaller drill diameters.

In a structurally simple attainment, the elastic lock is a spring element arranged on the rotary lock-in bar, which can be moved spring-elastically in a circumferential direction of the drill rod.

In a further structurally simple attainment, the elastic lock is a spring element arranged on the drill head, which can be moved spring-elastically in a circumferential direction of the drill head.

In an attainment that can be realized in an especially cost-effective manner, the elastic lock includes at least one elastic wall section of the drill head. At the same time, the width of the rotary lock-in slot in the region of the opening is smaller than the greatest width of the rotary lock-in bar. The elastic deformability of the drill head or its circumferential wall is utilized hereby in an advantageous manner.

A constricting of the rotary lock-in slot is advantageously achieved in that a projection narrowing the opening is arranged on the wall section in the region of the axial opening of the rotary lock-in slot.

In the process, it can be beneficial if a further slot is arranged in the wall section in a region lying in a working rotational direction behind the projection. The elastic widening of the opening or the constricted location is hereby facilitated when inserting and extracting the rotary lock-in bar from the rotary lock-in slot.

The rotary lock-in slot advantageously has at least one beveling in the region of its opening, wherein the widening of the opening or the narrow point of the rotary lock-in slot by the rotary lock-in bar is facilitated.

The invention is depicted in the drawings in an exemplary embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C are side views of the drilling tool according to the invention in three different stages of assembly;

FIGS. 2A to 2C are side views of another drilling tool in three different stages of assembly; and

FIG. 3 is a side view of another drilling tool where the drill head is not yet mounted on the drill rod.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C depict a first drilling tool 10 according to the invention, which extends along a tool axis A. This drilling tool 10 has a drill head 21, which bears a cutting body 29 made of hard metal, and an elongated drill rod 11. The drill head 21 and the drill rod 11 are connected via a coupling mechanism, which has four rotary lock-in slots 22 on the drill head 21 miming along the tool axis A and four rotary lock-in bars 12 arranged on a front end of the drill rod 11. Running lengthwise with or along a tool axis in this case also means a progression of the rotary lock-in slots 22 that is inclined at an angle of up to 25° from the tool axis A. The rotary lock-in bars 12 can each be inserted via axial openings 28 of the rotary lock-in slots 22 into the associated rotary lock-in slots 22 in order to arrange the drill head 21 detachably but rotationally secured on the drill rod 11. The openings 28 each have a beveling 27 as an insertion facilitator for the rotary lock-in bars 12 on at least one side of the openings 28. The rotary lock-in bars 12 are preferably conically tapered on their ends facing the drill head 21 in order to facilitate insertion into the rotary lock-in slots. In the region of the openings 28, a locking nose 30 projects respectively into the rotary lock-in slots 22 on the ends of the rotary lock-in slots 22 lying in the working rotational direction R and according to a type of bayonet lock prevents the disengaging of the rotary lock-in bars 12 during drilling operation.

Arranged on at least one of the rotary lock-in bars 21, on the side that is opposite from the working rotational direction R, is a spring element 13 embodied as a spring bridge, which acts as an elastic lock and via which the drill head. 21, if it is attached to the drill rod 11 as FIG. 1C shows, is acted upon elastically against the working rotational direction R. The rotary lock-in bars 12 are thereby held in the regions of the rotary lock-in slots 22 that are partially axially closed via the locking nose 30. The spring element 13 in this case can move at least to a limited extent spring-elastically in a circumferential direction of the drill rod 11. The drill head 21 is held securely and captively on the drill rod 11 via the coupling mechanism in combination with the elastic lock.

The drilling tool 10 depicted in FIGS. 2A to 2C differs from the drilling tool depicted in FIGS. 1A to 1C in that, in this case, instead of the spring element 13 on the rotary lock-in bar 12, a spring element 23 embodied as a spring tongue is arranged as an elastic lock in at least one of the rotary lock-in slots 22, which spring element can be moved spring-elastically in a circumferential direction of the drill head 21. The function of the spring element 23 corresponds in this case to what was described in the foregoing with respect to FIGS. 1A to 1C, which is why in this regard and because of reference numbers not mentioned here, reference is made fully to the description of FIGS. 1A to 1C.

The drilling tool 10 depicted in FIG. 3 differs from the drilling tool depicted in FIGS. 1A to 1C in that, instead of the spring element 13 on the rotary lock-in bar 12, the elastic lock in this case includes at least one elastic wall section 24 of the drill head 21 and at least one projection 25 projecting from the wall section 24 and narrowing the rotary lock-in slot 22 in the region of its axial opening 28. Moreover, a further slot 26 is arranged next to the wall section 24 in a region lying in a working rotational direction R behind the projection 25, which slot increases the elastic flexibility of the wall section 24. The projection 25 in this case has the beveling 27 in the design as a curved outer contour, which facilitates the widening of the opening 28 of the rotary lock-in slot 22 by the rotary lock-in bar 12.

The function of the elastic wall section 24 corresponds in this case to the function of the spring elements 13, 23 described in the foregoing with respect to FIGS. 1A to 2C, which is why in this regard and because of reference numbers not mentioned here, reference is made fully to the description of FIGS. 1A to 2C.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.