Abstract
A core drill is arranged to drill in the ground, the core drill having a sleeve with a first end portion and a bit ring which is detachably attached in a rotationally rigid manner to the first end portion, one of the sleeve and the bit ring having a groove with two converging side faces, and the other one of the sleeve and the groove having a protrusion with two complementary side faces, and the groove and the protrusion being arranged to engage with each other.
Claims
1. An annular cutter arranged to drill in the ground, the annular cutter comprising: a sleeve with a first end portion; and a bit ring, wherein one of the sleeve and the bit ring has a groove with two converging side faces, and the other one of the sleeve and the bit ring has a protrusion with two complementary side faces, and the groove and the protrusion are arranged to engage with each other to create a friction surface between the bit ring and the sleeve; and the bit ring is rotationally rigid and detachably attached to the first end portion of the sleeve via a coupling arranged between the first end portion of the sleeve and the bit ring.
2. The annular cutter according to claim 1, wherein the protrusion is arranged on the bit ring.
3. The annular cutter according to claim 1, wherein the coupling is arranged to absorb an axial force which is greater than an axial lifting force necessary for lifting the annular cutter out of the ground, the coupling being placed between the first end portion of the sleeve and the bit ring.
4. The annular cutter according to claim 1, wherein the coupling comprises fastening means taken from a group comprising screws, clamping sleeves and wedges.
5. The annular cutter according to claim 1, wherein the fastening means is arranged in a cut-out in the end face of the sleeve.
6. The annular cutter according to claim 3, wherein the coupling includes a coupling body.
7. The annular cutter according to claim 1, wherein the first end portion of the sleeve and the bit ring comprises complementary toothings arranged to prevent relative rotation between the sleeve and the bit ring.
8. The annular cutter according to claim 1, wherein the bit ring includes several detachable teeth.
9. An assembly comprising an annular cutter and a drive unit, the annular cutter being connected to the drive unit comprising: a sleeve with a first end portion; and a bit ring, wherein one of the sleeve and the bit ring has a groove with two converging side faces, and the other one of the sleeve and the bit ring has a protrusion with two complementary side faces, and the groove and the protrusion are arranged to engage with each other to create a friction surface between the bit ring and the sleeve; and the bit ring is rotationally rigid and detachably attached to the first end portion of the sleeve via a coupling arranged between the first end portion of the sleeve and the bit ring.
10. The annular cutter according to claim 2, wherein the coupling is arranged to absorb an axial force which is greater than an axial lifting force necessary for lifting the annular cutter out of the ground, the coupling being placed between the first end portion of the sleeve and the bit ring.
11. The annular cutter according to claim 4, wherein the coupling includes a coupling body.
12. The annular cutter according to claim 5, wherein the coupling includes a coupling body.
Description
EXEMPLARY EMBODIMENTS
[0028] In what follows, examples of preferred embodiments are described, which are visualized in the accompanying drawings. For the sake of order, it is pointed out that FIGS. 1 and 14-19 describe the first aspect of the invention. FIGS. 4-7 and 12-3 show solutions that may be combined with the first aspect of the invention. FIGS. 2-3 and 8-11 show solutions on which the invention has been built, but which are not combinable with the first aspect of the invention:
[0029] FIG. 1 shows an annular cutter according to the invention with a first coupling of a bit ring;
[0030] FIG. 2 shows the coupling of FIG. 1 on a larger scale;
[0031] FIG. 3 shows a section of FIG. 2;
[0032] FIG. 4 shows an annular cutter with a second coupling of the bit ring;
[0033] FIG. 5 shows a section of the bit ring of FIG. 4 on a larger scale;
[0034] FIG. 6 shows the second coupling on a larger scale;
[0035] FIG. 7 shows a section of FIG. 6;
[0036] FIG. 8 shows a third coupling of the bit ring;
[0037] FIG. 9 shows a section of FIG. 8;
[0038] FIG. 10 shows a fourth coupling of the bit ring;
[0039] FIG. 11 shows a section of FIG. 10;
[0040] FIG. 12 shows a fifth coupling of the bit ring;
[0041] FIG. 13 shows a section of FIG. 12;
[0042] FIG. 14 shows a sixth coupling of the bit ring;
[0043] FIG. 15 shows a first section of FIG. 14;
[0044] FIG. 16 shows a second section of FIG. 14;
[0045] FIG. 17 shows an alternative embodiment of the sixth coupling shown in FIG. 16;
[0046] FIG. 18 shows a bit ring as shown in FIG. 14, on a smaller scale; and
[0047] FIG. 19 shows a section of FIG. 18 on a larger scale.
[0048] FIG. 1 shows an annular cutter 1 according to the invention, the annular cutter 1 being in an operative position in a ground 99. The annular cutter 1 comprises a sleeve 2 and a bit ring 3. The bit ring 3 is detachably attached in a rotationally rigid manner to the sleeve 2 via a first coupling 4a. The annular cutter comprises a plurality of couplings 4a. The annular cutter 1 is arranged in a drilling rig 5 comprising a drive unit 51 and a lifting device 52 arranged to raise and lower the annular cutter 1. The couplings 4 are arranged to absorb a force F1 which is greater than the maximum lifting force F2.
[0049] FIGS. 2 and 3 show, from the side and in a cross section A-A, respectively, the coupling 4a. The sleeve 2 is provided with an end face 21 and an internally threaded portion 23. The bit ring 3 is provided with a corresponding end face 31 and a through cut-out 33. A tooth 35 is attached to the bit ring 3. A screw 12 has been passed through the cut-out 33 of the bit ring 3 and screwed to the threaded portion 23. The head diameter 12d of the screw 12 is smaller than the thickness 3d of the bit ring, and the height 12h of the screw is smaller than the height 40h of the tooth body. Thereby the screw head is protected in a tangential direction during drilling.
[0050] FIG. 4 shows an annular cutter 1 with a second coupling 4b. The sleeve 2 and the bit ring 3 are provided with corresponding toothings 29, 39. The bit ring 3 is detachably attached to the sleeve 2 via the coupling 4b. The coupling 4b includes a screw 12 arranged axially, shown in FIGS. 6 and 7.
[0051] FIG. 5 shows a cross section, on a larger scale, of the bit ring of FIG. 4. The bit ring 3 is provided with six axial cut-outs 34 and six corresponding radial cut-outs 33. The axial cut-outs 34 are arranged to receive and enclose the screw 12, shown in FIG. 4. The radial cut-outs are arranged to protect the screw 12. The cut-out 33 gives an angle of motion A1 for a tightening tool. A wider cut-out 33 may give a wider angle of motion A2. See FIGS. 6 and 7 for more details.
[0052] FIGS. 6 and 7 show, on a larger scale, the second coupling 4b shown in FIGS. 4 and 5, from the side and in a section C-C, respectively. The cut-out 34 has a size and shape that make it possible to pass the screw 12 through the cut-out 33 and then screw the screw 12 to the sleeve 22 with a tool. The tooth 35 is attached to the sleeve 3.
[0053] FIGS. 8 and 9 show a third coupling 4c, from the side and in a section D-D, respectively. The bit ring 3 is slipped over the sleeve 2 and attached with a countersunk screw 13 arranged radially. The end face 31 of the bit ring 3 is arranged to rest supportingly against the end face 21 of the sleeve 2. The tooth 35 is attached to the sleeve 3.
[0054] FIGS. 10 and 11 show a fourth coupling 4d, from the side and in a section E-E, respectively. In principle, the fourth coupling 4d is identical to the third coupling 4c, with the difference that the countersunk screw 13 has been replaced by a clamping sleeve 14. FIGS. 9 and 10 further show a detachable tooth 36, attached to the bit ring with two screws 37.
[0055] FIGS. 12 and 13 show a fifth coupling 4e, from the side and in a section F-F, respectively. The fifth coupling 4e comprises a coupling body 16 which is locked to the sleeve 2 and the bit ring 3 by means of two set screws 15. To prevent relative motion between the sleeve 2 and the bit ring 3, an annular cutter 1 provided with coupling bodies 16 should include at least three coupling bodies 16 evenly spaced along the circumference of the annular cutter 1. The tooth 35 is attached to the sleeve 3.
[0056] FIGS. 14-16 show a sixth coupling 4f, from the side and in a section G-G and in a section H-H, respectively. The sleeve 2 and bit ring 3 are provided with a conical coupling portion 60, in which the bit ring 3 has a protrusion 63 with two converging side faces 64 and the sleeve 2 has a groove 61 with two complementary side faces 62, the protrusion 63 and the groove 61 being arranged to engage with each other.
[0057] The conical coupling portion 60 is so formed that an axial clearance 61 is created between the top of the protrusion 63 and the bottom of the groove 61. Thereby a greatest possible contact between the sloping faces 62, 64 is ensured.
[0058] When the screw 12 (FIG. 15) is tightened, the surface pressure and thereby the friction between the first and second sloping surfaces 62, 63 will increase.
[0059] FIG. 17 shows an alternative embodiment of the conical coupling portion shown in FIGS. 14-16, the protrusion 64 being arranged on the sleeve 2 and the groove 61 being arranged on the bit ring 3.
[0060] FIG. 18 shows the bit ring of FIGS. 14-16 in perspective.
[0061] FIG. 19 shows a section of FIG. 18.
[0062] It should be noted that all the above-mentioned embodiments illustrate the invention, but do not limit it, and persons skilled in the art may construct many alternative embodiments without departing from the scope of the attached claims. In the claims, reference numbers in brackets are not to be regarded as restrictive.
[0063] The use of the verb to comprise and its different forms does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article a or an before an element does not exclude the presence of several such elements.
[0064] The fact that some features are indicated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.
