drill

Abstract

Drill with a drill head and a clamping end of the drill, between which a spiral helix formed from a drilling dust removal groove and a web extends, the web width of which decreases from the drill head to the clamping end, characterized in that the drill (10) has a constant core diameter in the region of the spiral helix (16), and in that at least one chamfer (30) extends on the spiral helix (16), the width of which changes at least partially over the course from the drill head (12) to the clamping end (14), in particular over the entire course.

Description

[0001] The invention relates to a drill with a drill head and a clamping end of the drill, between which a spiral helix formed by a drilling dust removal groove and a web extends.

[0002] A drill with a specially designed spiral helix is known, for example, from DE 202 19 563 U1. In this drill, an intermediate helix extends into the drilling dust removal groove of the spiral helix.

[0003] Because the web of the intermediate helix springs back, it does not rub against the drill hole, so that no additional friction is created, but the intermediate helix is able to transport the drilling dust.

[0004] The document DE 23 58 447 B1 relates to a rock drill with a maximum nominal diameter of 12 mm for rotary percussion drilling machines, with a drilling cutting edge and several drilling dust grooves cut into the drill shaft, the respective base area of which runs essentially parallel to the axis and is provided with roundings to its adjacent lateral flanks, the radius of which is smaller than the groove depth.

[0005] The document DE 197 53 731 A1 relates to a rock drilling tool for rotating or percussive loading, with a drill head, a single- or multi-start, spiral conveyor helix connected thereto with at least one removal groove for drilling dust and a clamping shaft.

[0006] The document JP 2006-198724 A relates to a drill in which a plurality of torsion grooves extend from the cutting end to the base end.

[0007] On the other hand, drill bits with large dust removal grooves that are not interrupted by an intermediate helix are less prone to clogging. This is especially true for holes drilled horizontally or vertically downwards, and for holes drilled in brick, stone, or concrete.

[0008] Drills suitable for this purpose are typically equipped with a carbide plate that breaks up the material in the bottom of the borehole through the impact action of the hammer drill or hammer drill, thus ensuring advancement.

[0009] On the other hand, a precisely round drill hole with a specified diameter is often desired. This is especially true when determining the drill hole for wall anchors, which expand, but by a smaller amount than, for example, standard dowels.

[0010] To create appropriate drill holes, the spiral helix has a typically specified diameter and a typically specified web width, depending on the application, which allows drill holes to be created with the desired quality. Drill holes are typically created at different depths, with the depth range covered by a drill bit varying, for example, between 5 cm and 50 cm. With such drills, the front areas of the spiral helix typically experience greater wear, so that in shallower drill holes, a kind of wobbling motion of the drill bit in the hole can occur, which prevents the desired accuracy.

[0011] In contrast, the invention is based on the object of creating a drill according to the preamble of claim 1, which enables a consistent quality of boreholes both in shallower and deeper boreholes.

[0012] This object is achieved by an object according to claim 1. Advantageous further developments emerge from the subclaims.

[0013] The spiral helix is designed to have a chamfer whose width varies along the helix. This allows the remaining width of the web in contact with the drill hole to be adjusted to requirements without weakening the drill bit overall: If, for example - as will often be the case - the susceptibility of the drill to wear is particularly high in the area of the web of the spiral helix at the front, a particularly large web width is used there so that wear is reduced.

[0014] A particularly advantageous feature is that, compared to conventional drills, this drill has a significantly lower tendency to spiral breakage. While with conventional drills, wear is greatest just behind the drill head, which leads to the dreaded tapering of the drill bit and also to the drill bits breaking there, this type of tapering is avoided because the point where the removal forces are greatest also has the most material resisting the removal.

[0015] It is particularly advantageous that in the area adjacent to the clamping end, the width of the web back is reduced with increasing chamfer width, which benefits the reduction of friction without impairing the rigidity and stability of the drill.

[0016] Surprisingly, the impact energy of the drill can be fully transmitted due to the reduced back width and the resulting lower mass, especially in the area adjacent to the introduction of the impact energy, i.e. near the clamping end, which increases the efficiency of the drill.

[0017] It is particularly advantageous that the increase in friction when the drill is immersed more deeply is automatically compensated: In the front area, the full width of the ridge rests against the drilled hole, generating the corresponding friction. As the drill continues to penetrate the hole, friction increases, but this is significantly less than proportional to the fact that the ridge width decreases with the increasing width of the chamfer toward the clamping end.

[0018] The reduction in the web back width can be 30%, 40% or even 60%, or even up to 75%, which is accompanied by a corresponding reduction in the friction surface.

[0019] However, the wear on the spiral coil is not reduced; rather, the conical wear typical of conventional spiral coils is compensated.

[0020] It is also advantageous that the depth of the drilling dust removal groove remains the same towards the clamping end and at least does not decrease, so that there is sufficient space for the drilling dust to be removed.

[0021] It is therefore particularly advantageous that an increasing chamfer and correspondingly smaller back width are accompanied by lower load and friction, which also improves the efficiency of the drill. When the drill is almost completely immersed in the hole, the increase in rotational resistance of the drill is at least partially compensated by the lower increase in friction during immersion.

[0022] It is also particularly advantageous that the mass distribution on the web of the spiral helix is uneven along the drill's length. Given the constant core diameter, the web mass decreases from front to back, with the decrease being between 5% and 15%. This is surprisingly sufficient to avoid resonances caused by the introduced longitudinal pulses.

[0023] In some cases, the drill bit is held slightly angled relative to the borehole axis when drilling the hole, either unintentionally or to widen the end of the hole. This is generally not a problem for the drill bit when drilling into brick. However, when drilling into concrete, the spiral helix may come into contact with reinforcement or at least embedded stone, which frequently damages the spiral helix at the contact point.

[0024] The chamfer prevents or at least reduces damage, because the spiral helix hits the stone in a blunt manner in the rear area, and the angled position mainly acts in the rear area of the drill, i.e. near the clamping end, where the chamfer is at its largest.

[0025] Further advantages, details and features will become apparent from the following description of two embodiments of the invention with reference to the drawings.

[0026] They show: Fig. 1: A side view of a drill in one embodiment; Fig. 2: An enlarged view of a detail of the drill according to Fig. 1; and Fig. 3: A modified design of the drill according to Fig. 1.

[0027] The Fig. The drill 10 shown in Figure 1 has a drill head 12 and a clamping end 14, between which a spiral helix 16 extends. The spiral helix 16 rotates around a core 18 of the drill with a constant core diameter. In the illustrated embodiment, the core diameter is the same size as the diameter of the drill at the clamping end 14.

[0028] The spiral coil 16 is formed by two spirals 20 and 22, which rotate in a manner known per se and are each designed in the shape of a web. The spirals 20 and 22 have a substantially rectangular cross-section from their back 24 to the core 18, wherein the transition between the web 23 and the core 18 is smoothed out in a manner known per se by radii 26 and 28, which are better Fig. 2 are visible.

[0029] A chamfer 30 extends on the drill head side of the spiral helix 16, which, as it were, breaks the drill head-side edge of the web 23. This chamfer changes in width over the course of the drill, whereby in the illustrated embodiment, its width increases, viewed from the drill head 12 to the clamping end 14.

[0030] As the width of the chamfer 30 increases, the remaining width of the web's back also changes accordingly. At the drill head end of the spiral helix 16, the back width is extremely large, and toward the clamping end 14, it is reduced to less than half of this back width in the illustrated embodiment.

[0031] In a modified embodiment, it is also possible to reduce the back width at the clamping end 14 almost to zero.

[0032] Out of Fig. Figure 2 shows an enlarged view of a portion of this drill. As can be seen, the width of the chamfer increases over the three illustrated turns of the spiral helix 16. In this embodiment, it is slightly concave, which can be easily achieved with a milling head of a suitable diameter.

[0033] Out of Fig.3 shows a drill 10. The hard metal plates are attached to the drill head 12 in a conventional manner. It can be seen that in this embodiment, the width of the drilling dust removal groove 32 increases slightly over the course of the drill from the drill head end 12 to the clamping end 14, coupled with an increase in the width of the chamfer 30.

[0034] Here too, the diameter of the core 18 is constant, and the groove base 34 of the drilling dust removal groove 32 is designed slightly obliquely between the individual spiral turns of the spiral helix 16, so that its normal points slightly backwards towards the clamping end 14 in order to further improve the drilling dust removal groove by scooping effect.

[0035] It is understood that the exact design, for example, the size of the radii 26 and 28, can be adapted to requirements within a wide range, and that it is also possible to vary the width of the chamfer 30 in any way along the course of the drill, for example, by initially increasing it, then decreasing it, and then increasing it even more. The angle of inclination of the chamfer 30, which here is approximately 45 degrees to the drill axis, can also be adapted to requirements within a wide range, and the chamfer can also be designed in any way—convex or concave, flat or profiled.

Claims

[1] Drill with a drill head and a clamping end of the drill, between which extends a spiral helix formed by a drilling dust removal groove and a web, the web width of which decreases from the drill head to the clamping end, characterized by that the drill (10) has a constant core diameter in the region of the spiral helix (16), and that at least one chamfer (30) extends on the spiral helix (16), the width of which chamfer changes at least partially over the course from the drill head (12) to the clamping end (14), in particular over the entire course. [2] Drill according to claim 1, characterized by that the width of the chamfer (30) increases from the drill head (12) to the clamping end (14). [3] Drill according to one of the preceding claims, characterized by that the spiral coil (16) has more than one spiral (20, 22), in particular two spirals (20, 22), and that each spiral has a chamfer (30).

Images