FAANES PER AAGE (NO)
| SE403066B | 1978-07-31 | |||
| DE3842683A1 | 1990-03-15 | |||
| DE2415240A1 | 1975-10-16 | |||
| US4978258A | 1990-12-18 | |||
| NO302587B1 | 1998-03-23 |
| 1. | 1. A device for drilling a conical zone at the end of a drilled cylindrical hole in rock, stone, concrete or other drillable material, for fixing screws, safety bolts or similar. c h a r a c t e r i s e d i n that the device comprises a drill head (1) coupled to a swingout cone joint (2) with a flexible and resilient Oring (15). and the drill head and the cone joint have a through passage (11,13) for introduction of compressed air or drill fluid. A device according to Claim 1, c h a r a c t e r i s e d i n that the swingout cone joint (2) is attached to the drill head (1) via a solid through bolt (4), the cone joint (2) may swing out to a predetermined radius (8) by coming to a stop against an edge (10) at the bottom of the drill head 3. A device according to Claims 12, c h a r a c t e r i s e d i n that the cone joint (2) is equipped with at least one, preferably three longitudinal carbide segments (5). *& 4. |
| 2. | A device according to Claim 1, c h a r a c t e r i s e d i n that the Oring (15) on the cone joint (2) is preferably made from a flexible, resilient rubber.*& 5. |
| 3. | A device according to Claims 14, c h a r a c t e r i s e d i n that compressed air may be introduced through the passages (11, 13).*& 6. |
| 4. | c h a r a c t e r i s e d i n thatthedevice is equipped with standard thread, so as to allow it to be coupled to commonly used drill rods.*& 7. |
| 5. | A device according to Claims 16, c h a r a c t e r i s e d i n that the cone joint (2) has a hollowed out area (12) at the top in order to enhance the transfer of compressed air between the passages (11) and (13). |
It is previously known that a certain amount of conisity may be formed at the bottom of a drilled hole, and that this may be done by use of various types of devices and drills. A great drawback to these solutions is the fact that they are complicated and often do not give satisfactory results, in addition to the fact that no compressed air or drill fluid is fed to the hole during drilling. This results in the drilled materials remaining at the innermost end of the hole and having to be removed by means of e. g. compressed air after the conical area has been drilled. Unlike these known solutions, the device of the invention ensures that compressed air is introduced, so as to remove the drilled materials while the drilling takes place.
The basis of the invention is the fact that it is often difficult to create solid and firm anchorage points in rock, stone, concrete and similar hard materials. It turns out that only cylindrical holes are normally drilled for fixing bolts and screws in these materials.
In other words, the bolts are only held by the frictional forces between the bolt and the cylindrical, straight wall.
Use of the device of the invention to drill a conical area at the bottom of a cylindrical hole will provide a much stronger and firmer anchor at the innermost end of the drilled hole.
Various ways of drilling conical holes have previously been described. EP 704 226 is especially aimed at a device for drilling holes in face tiles. DE 2 415 240 describes a method and device for drilling conical holes. US 5 829 925 describes a drill with a cutting device at the end, which device may be forced out by means of pressurised drill fluid. US 4 978 258 is aimed at a drilling tool with a swing-out head for drilling cavities.
The present invention regards a device for drilling a conical zone at the end of a predrilled cylindrical hole in rock, stone, concrete, bricks or other drillable material for fixing screws, safety bolts, the device being characterised in that it comprises a replaceable drill head coupled to a swing-out cone joint with a resilient O-nng, where the ball joint is attached to the drill head by use of a through bolt, and where the drill head. the bolt, the ball head with the cone joint have through holes for introduction of compressed air or drill fluid for removal of drilled materials.
By both the drill head and the cone joint having through holes for introduction of compressed air or drill fluid, even at all angles of the cone joint, the drilled hole will at all times be free of drilled materials, cuttings and other loose materials.
When drilling large holes in rock and coning the lower part of the hole, great forces must be applied to the actual drill head in the form of powerful blows and rotation. The device of the invention is formed with a ball joint in which the actual ball is to withstand the percussion forces applied and a sturdy through bolt is to withstand the rotational forces.
The invention will now be explained in greater detail by means of the figures, in which Fig. 1 shows a cross section of the entire drill head with a ball-attached joint and a swing-out cone joint, Fig. 2 shows a cross section of the cone joint, seen from the side, Fig. 3 shows a top view of the drill head, Fig. 4 shows a conventional rock drill at the bottom of a drilled hole, Fig. 5 shows the cone joint of the invention while drilling a conical bottom.
Fig. 6 shows an example of a taper bolt that has been hammered down and secured.
Figures 1,2 and 3 show the drill head 1 with a threaded portion 3 that is screwed onto a drill rod. The cone joint 2 that can be forced outwards to drill a conical hole is attached by use of a through bolt 4. The bolt 4 has a hollowed out area 14 in the middle, so as to allow compressed air to pass through in all positions of the cone joint 2. Carbide
segments 5 have been mounted on the side of the cone joint 2 facing the drilled hole.
These will ensure quicker. improved drilling of the conical area and make the drill more durable. A central passage 11 and 13 for introduction of compressed air goes through the drill and the cone joint 2. A hollowed out area 12 existes in the region between the cone joint 2 and the drill head, the function of which area is to ensure the free passage of compressed air even when the cone joint 2 is in its extreme position. In figure I, the broken line 9 illustrates the bottom of the drilled hole, and the broken line 8 shows the ready drilled conical zone. A rubber O-ring 15 is fitted to the upper part of the cone joint 2. the effect of which is to force the cone joint back to its original position after drilling. The lower edge of the cone joint 2 is rounded with a bevel 6. When the cone joint 2 reaches the ready drilled position, the cone joint will come to a stop against the lower stop edge 10 of the drill head. Thus this edge ensures the maximum deflection of the cone joint.
Figure 3 shows the drill head 1 with the cone joint 2 seen from above, with carbide segments 5. The through bolt 4 is indicated by broken lines, and provides swivelling attachment of the cone joint 2 to the drill head.
Figure 4 shows a conventional rock drill 16 drilling a cylindrical hole in rock 17. The drilling is carried out until the hole has reached the desired depth 9.
Figure 5 shows the hole drilled in Figure 4, but with the cone joint 2 mounted on a drill head and a conical hole 8 drilled at the bottom of the hole. Due to the lower bevel 6 of the cone joint, the joint will, as a result of rotation and hammering on the drill head, be forced outwards and will drill a conical hole 8. The swivel radius of the cone part is limited as it hits the lower stop edge 10. When the conical hole is ready drilled, the rotation and hammering on the drill head is stopped. At this point the rubber O-ring 15 will force the cone joint back to its original position, to allow the whole thing to be withdrawn from the hole. Drilled materials will already have been carried out of the hole bv compressed air.
Figure 6 shows an example of a taper bolt 18 that has been inserted into the hole. A pipe 19 is then placed around the outside of the taper bolt 18 and knocked down towards the
bottom of the hole. As a result of the force applied during the hammering, the pipe 19 is forced out by the conical part of the bolt 18 and fills the surrounding space. This provides a very safe fixing and anchoring system.
The diameter, length and angle of the cone joint may be adapted to the desired dimensions.
The entire drill head and the cone joint are preferably provided with standard special threads. These are matched to the thread used on drill rods for drilling in rock, stone, concrete and similar, for securing and anchoring conventional rock safety bolts and other fastening devices. By using special standard thread, drill heads and cone joints may be replaced quickly.