[0030] Fig. 1 shows a drilling tool designed according to the present invention, which is generally designated by the symbol 1, and the figure shows that it has been installed in a tool mount R of a drill M, such as a percussion drill. The drilling tool 1 has a sleeve-shaped rod 2 with a through hole 3. The tubular rod 2 is connected to the connecting part 4 at one end thereof, for example, by brazing. The connecting part has an insertion end 5 for connecting to the tool mounting seat R of the drilling machine M. The through hole 3 communicates with a hole 6 in the connecting part 4, which opens into a hole 7 at the periphery of the connecting part 4. In the axially elongated section of the tool mounting seat R, a torsion-transmitting joint C is provided on the drill M, which is equipped with an annular cavity S, and the annular cavity S communicates with the outlet hole 7 of the hole 6 in the connecting part 4. The annular cavity S is connected to the connecting pipe N, and the suction hose H is connected to the connecting pipe N. At the end of the sleeve-like rod 2 opposite to the connecting part 4, the drilling tool is equipped with a drill bit 8, which has a drill edge 9 and is entirely made of cemented carbide. The drill bit 8 has at least one suction channel, which extends obliquely with respect to the through hole 3 in the rod 2 of the drilling tool 1 and opens into the hole 10 on the side of the drill blade 9.
[0031] The joint C of the drill M is connected to a suction device not shown further in the figure, such as a vacuum cleaner, via a suction hose H. When the vacuum cleaner is switched on, through the suction hose H, the ring cavity 5, the hole 6 in the connecting part 4, the through hole 3 and the suction channel inclined in the drill bit 8, a negative effect is generated at the hole 10 on the side of the drill blade 9 Pressure. Due to this negative pressure, the cuttings cut by the drill blade 9 during drilling are drawn to the suction hose H through the drill bit 8, the through hole 3 in the sleeve-like rod, and the hole 6 in the connecting part 4 and transported to the vacuum cleaner.
[0032] The drawings in Figures 2-7 are limited to drilling tools that are an important part of the present invention. In the embodiment of the drilling tool shown in FIGS. 2 and 3, which is generally designated 11, it can be seen that the drill bit 15 has a drill edge 16 extending diagonally. The portion of the drill bit 15 with a drill edge protrudes from the outer diameter of the sleeve-shaped rod 12 and is mounted in two grooves 19, which are provided at the front end of the rod 12 opposite to each other. The area between the drill blades 16 is designed to expand to both sides into a semicircle. In this case, the outer contour 17 of the expansion part is coordinated with the contour of the inner wall 18 of the through hole 13 of the sleeve-like rod 12. The diameter of the drill 15 measured on the expanded portion is equal to the diameter of the through hole 13. This measure is taken to ensure that the drill bit 15 is in surface contact with the inner wall 18 of the rod 12 along most of its periphery. The part of the drill bit 15 embedded in the rod 12 is firmly connected to the material of the rod by brazing or welding. In this way, the drill bit 15 is designed to be guided and fixed by the inner wall 18 of the rod 12 in the groove 19 at the front end of the rod 12 along its entire circumference. A hole 14 is formed in the peripheral area of the front end portion of the rod 12 to communicate with the through hole 13.
[0033] FIG. 4 shows a plan view similar to FIG. 3 of the drilling tool 21 with the modified drill bit 25. The drill bit 25 has three cutting edges, which preferably extend at an angular distance of approximately 120° from each other. The part of the drill bit 25 with the drill edge 26 extends beyond the periphery of the sleeve-shaped rod 22 and is mounted in three corresponding grooves 29 at the front end of the rod 22. Two of the areas between the portions of the drill bit 25 with the cutting edges 26 have expanded portions whose outer contour 27 is consistent with the contour of the inner wall 28 of the rod 22 in order to obtain surface contact. In the third area between the two drill edges 26, the drill bit 25 is provided with a material space, because this material space forms the hole 24 of the through hole 23, which uses the wall of the drill bit 25 and the sleeve-like rod 22 The inner surface 28 is the boundary.
[0034] Figure 5 shows another version of the drilling tool 31 according to the invention. The drill bit 35 has a drill edge 36 extending diagonally, which is arranged on the portion of the drill bit 35 that protrudes from the outer diameter of the sleeve-shaped rod 32 and fits into a corresponding groove at the front end of the rod 32. There is a thickened area on one side of the drill 35, the outer contour 37 of which is consistent with the contour of the inner wall of the rod 32. The drill bit 35 shrinks on the opposite side toward its part inside the rod 32 and forms an orifice 34 which is bounded by the wall of the drill bit and the inner wall 38 of the sleeve-like rod 32. In each case, the orifice 34 can expand inwardly of the rod, and it extends obliquely inwardly from the end face of the rod 32.
[0035] The embodiment of the drilling tool according to the present invention shown in FIG. 6 is generally designated by the symbol 41. The rod is denoted by 42 and has an embedded section 40 of a reduced diameter serving as a drill bit 45 with a drill edge 46 designed as a drill plate. The embedded section 40 of the rod 42 with a smaller diameter is designed to be solid. This is achieved, for example, by reducing the diameter of the tubular rod 42 initially having a uniform diameter in the buried section 40 of the drill bit 45 later. The diameter can be reduced to such an extent that the through hole 43 in the front section 40 of the tubular rod 42 is substantially or completely closed. Then, the front section 40 with the reduced diameter is slotted from its front free end and the drill bit 45 is inserted into the slot 49 and then fixed by welding or brazing. The substantially flat side surface 47 of the drill bit 45 is in surface contact with the side wall 48 of the mounting groove 49 for the drill bit 45, and is firmly connected to it by brazing or welding. The through hole 43 passes through the hole 44, and the hole 44 is arranged below the embedded section 40 for the drill bit 45.
[0036] Fig. 7 shows a plan view of another embodiment of a drilling tool according to the present invention, which is generally designated 51. The drilling tool 51 has a rod 52 whose cross-section is not circular. The front section 50 of the rod 52 used as the embedding section of the drill 55 has some recesses. These recesses are designed so that the drill bit 55 provided with three drill edges 56 has as large a brazing surface as possible. Therefore, a substantially polygonal outer contour is formed for the embedded section 50. The grooves 59 for mounting the drill bit 55 are arranged so that they extend at an angle of approximately 90°±10° with respect to the outer surface of the embedded section 50. The hole 54 in the peripheral region of the rod 52 communicates with the through hole 53. Among them, a hole 54 is provided for each drill edge 56 of the drill 55. The orifices are arranged such that there is an angular distance of less than 90° between the drill edge 56 lagging in the direction of rotation and the orifice in front.
[0037] Particularly from the top views in Figures 3, 4 and 7, it can be seen that the parts of the drill bits 15, 25, 55 with the cutting edges 16, 26, 56 are installed in the grooves 19, 29, 59, each of which has a preferably 90° to each other. The rods 12, 22, 52 are arranged at the front ends of the rods 12, 22, 52 at an angular distance of up to 180°. It can be seen from all the figures that the orifices 10, 14, 24, 34, 44, and 54 have smaller cross-sectional areas than the through holes 3, 13, 23, 33, 43, and 53, respectively. Advantageously, the cross-sectional area of the orifices 10, 14, 24, 34, 44, 54 is approximately 30% to 70% of the cross-sectional area of the through holes 3, 13, 23, 33, 43, 53. In the case of multiple orifices, the sum of their cross-sectional areas is preferably smaller than the cross-sectional area of the through holes. In the embodiments shown in the drawings, each is represented as a substantially circular through hole 3, 13, 23, 33, 43, 53. It goes without saying that, in an alternative embodiment, the cross-section of the through hole of the sleeve-like rod may also be different from the circular shape if it is required to better embed the drill bit. For example, it may be elliptical, or it may have a polygonal shape. It is not critical for the implementation of the present invention that the sleeve-shaped rod has a circular outer contour. For example, the rod may also be elliptical, or may have a curved-sided triangle shape as shown in FIG. 7, or may have a regular hexagonal shape.
[0038] In FIG. 1, the drilling tool 1 according to the invention is illustrated by means of a connecting part 4 brazed to the rod with an insertion end 5. The connecting part 4 may also be connected to the rod 2 by friction welding, for example. Obviously, the insertion end can also be designed directly on the sleeve-shaped rod, for example. In this case, a modified tool mount and an integrated suction device are required. The drilling tool according to the present invention describes its application as a suction drill. It goes without saying that the described drilling tool can also be used in the opposite way of working. For example, the through hole with its outlet can also be used to flush the borehole with the aid of air or a flushing fluid.
