Stone drill

Abstract

This drill has an integrally formed extension (3) at its front end, which is smaller in diameter than the other drill bit (1). The extension (3) at the front end of the drill bit (1) preferably has a diameter d that is half the diameter D of the remaining drill bit (1) located behind the extension (3). The drill bit allows for perfect positioning, centering, and guidance of the hole along the intended drilling line.

Description

[0001] Previous masonry drill bits for hand drills are widely used and all look roughly the same. At their front end, they taper to an obtuse-angled tip, forming an angle of approximately 150°. Behind the drill tip is a steep, helical groove through which the drilled debris is expelled to the rear during drilling.

[0002] Anyone who has ever had to drill holes in stone or concrete using a hand drill and such a drill bit can confirm that it is a problem to position and guide the drill bit precisely on a line. You mark the drilling location on the stone or concrete, for example with a cross or X, and position the drill bit in the center. After the drill is operated, the drill bit begins to rotate and then often tends to wander away from the center until it engages and penetrates the stone or concrete. This means that holes are often drilled into the stone or concrete slightly from the actual planned point, or after the drill bit wanders in this way, attempts are made to guide it at a slightly oblique angle to the intended drilling line to compensate for this deficiency.

[0003] The object of this invention is to remedy this deficiency and to create a drill bit which can be easily centered on the stone or concrete and which then allows the drill bit to be inserted exactly at the intended location and to penetrate exactly along the intended drilling line.

[0004] This task is solved by a drill for stone or concrete, which is characterized by the fact that its front end is one piece and ends in an extension of smaller diameter.

[0005] In the figures this drill is shown in an example version and based on these figures it is described in detail in the following description and its handling and function are explained.

[0006] It shows: Fig. 1: A conventional stone drill; Fig. 2: On the left the front end of a conventional stone drill and on the right the front end of the drill according to the invention; Fig. 3: A drill according to the invention during the initial drilling of a borehole, after it has penetrated a certain distance into the stone or concrete, shown in a section of the borehole; Fig. 4: A drill hole created with the drill according to the invention after inserting a dowel, shown in a section of the drill hole; Fig. 5: A conventional drill bit during preparation and the black marked vulnerable areas at the later opening; Fig. 6: A drilled hole with a conventional drill bit, showing missing chipped parts at the mouth and with the dowel inserted; Fig. 7: The drill bit according to the invention in use, after the extension has penetrated into the stone or concrete and the drill bit is positioned at the desired thickness on the hole pre-drilled by the extension; Fig. 8: A drill hole in concrete, created with a drill bit according to the invention, into which a dowel was inserted, and a screw inserted into the dowel.

[0007] First, the Fig. 1, a conventional masonry drill bit. This has a conically tapered tip 20, which forms an obtuse angle of approximately 150°. Behind the hardened steel drill head 21, the drill bit forms a steep, helical groove 22 through which the drilled debris is conveyed backward into the open during drilling.

[0008] The Fig. Figure 2 shows, on the left, the front end 20 of such a conventional stone drill with the corresponding drill head 21, and, next to it, that of the drill 1 according to the invention. As can be seen, this drill 1 has, at its front end 2, a one-piece extension 3 formed therefrom with a smaller diameter, which extends a few mm forward. In the example shown, the front end of the extension 3 forms a tip 2 whose angle is approximately 90°, i.e., it is more pointed than the tip of a conventional stone drill. This tip 2 can, however, equally well include an angle of 150° or less. The extension 3, as well as the frontmost area of ​​the drill 1 adjoining it at the rear, is made of hardened steel.A tip 2 of extension 3 with a smaller included angle facilitates the precise positioning of drill bit 1 and its targeted penetration into the first millimeter of drilling progress. This extension 3 then centers the further drilling process. For a drill bit diameter of 6 mm, for example, extension 3 itself has a diameter of approximately 3 mm, thus being half as thick. Its length I measures approximately 5 mm, although this measurement can vary by 1-3 mm.

[0009] The Fig. Figure 3 shows a drill bit 1 according to the invention during the creation of a borehole. First, the drill bit 1 was precisely positioned with the extension 3, and then the hole was drilled until the extension 3 completely penetrated the material 4. The extension 3 served as a guide, allowing the drill bit 1 to subsequently drill precisely along the planned drilling line. This also prevents damage caused by chipping in the borehole opening area.

[0010] The Fig. Figure 4 shows a drill hole created with the drill according to the invention after inserting a dowel 5. The dowel is split in two at the front, forming two legs 6, 7 that can be spread apart from one another. The dowel 5 is inserted all the way into the drill hole 8 with the larger diameter, while the area 9 drilled out by the extension 3 remains free. The dowel 5 sits neatly in the drill hole 8 up to the outer clean opening, thus ensuring maximum strength for the screw to be screwed in later.

[0011] The Fig. Figure 5 illustrates the often detrimental consequences that can occur when drilling into stone and concrete with a conventional drill bit. When starting and drilling, there is a risk of material 4 breaking off or chipping off around the emerging borehole opening. These vulnerable areas 10 are marked in black.

[0012] The Fig. Figure 6 shows a longitudinal section of a drill hole 8 created in this way. In the opening area 11, parts of the surrounding material 4 have chipped or broken off and are therefore missing. The opening is then funnel-shaped and no longer provides support for an inserted dowel 5 in the opening area 11. Accordingly, the strength of an inserted screw will be reduced.

[0013] The Fig. Figure 7 shows the drill bit 1 according to the invention in use after the extension 3 has penetrated the stone or concrete. The drill bit 1, with its larger diameter corresponding to the desired borehole diameter D, now strikes the opening created by the drilling of the extension 3. The drill bit 1 is perfectly guided and laterally stabilized by the extension 3 and cannot wander sideways, as often happens. If the drilling is continued, the drill bit 1 penetrates the material exactly along the desired drilling line and is still guided by the extension 3, which drills into the material as a kind of vanguard. For a drill bit 1 with a diameter D of 6 mm, the extension 3 will advantageously have a smaller diameter d of approximately 3 mm, so that the ring, which still has to be drilled and cleared by the thicker drill bit 1 during drilling, only has a ring width of approximately 1.5 mm, namely (Dd) / 2.The 3 mm diameter dimension for extension 3 also works well for various larger drill bit diameters, for example, for drill bits from 6 mm to 20 mm thick and more. Thus, a 5 mm long extension with a 3 mm diameter sits in the center of the drill bit, making it an ideal size for starting a hole, so that the surface of the concrete or stone next to the hole is not damaged. However, the extension can also be made slightly larger or smaller, for example, with 3 mm ± 20% in diameter and 5 mm ± 20% in length. Extension 3, when drilled in, also ensures secure guidance of the drill along the intended drilling line for enlarging the borehole.

[0014] Finally, the Fig.8 a drill hole 8 in concrete 4, created with a drill bit according to the invention. Here, a dowel 5 was inserted into the created drill hole 8, which finds a stop at the point 16 where the drill hole 8 narrows. A screw 12 was then screwed into the dowel 5, which here clamps a washer 13 with its screw head 14 onto the drill opening. The screw 12 sits with maximum strength in this dowel 5, which sits snugly in the drill hole 8 over its entire length, while the tip 15 of the screw 12, which projects beyond the dowel 5 at the front, projects into the free space 9 created by the extension 3 of the drill bit 1 according to the invention. The advantages are obvious: no chipping of material at the drill opening, perfect drill hole start without the drill bit wandering at the beginning of drilling, perfect centering and guidance of the drill bit along the desired drilling line.

Claims

[1] Drills for stone or concrete, characterized by that at its front end it terminates in a single piece in an extension (3) of smaller diameter. [2] Drill bit for stone or concrete according to claim 1, characterized by that the extension (3) at the front end of the drill (1) measures 3 mm ± 20% in diameter and 5 mm ± 20% in length. [3] Drill for stone or concrete according to one of the preceding claims, characterized by that the extension (3) ends in a tip at the front, which encloses an angle of 90° to 120°. [4] Drill for stone or concrete according to one of the preceding claims, characterized by that the extension (3) ends in a tip at the front, which encloses an angle of 90° to 150°. [5] Drill for stone or concrete according to one of the preceding claims, characterized by that the extension (3) has a length I which corresponds to twice the dimension ± 20% of its diameter d. [6] Drill for stone or concrete according to one of the preceding claims, characterized by that the extension (3) and the front end of the subsequent drill (1) are made of hardened steel.

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