DRILLING TOOL

Description

[0001] The invention relates to a drilling tool, and more precisely a drilling tool with a borehole length indicator according to the preamble of claim 1. The features of the preamble of claim 1 are known from publication FR 2 851 945 A1.

[0002] Drilling tools for drilling, in particular, masonry made of brick, concrete, reinforced concrete, and stone are known from the prior art, trade, etc. Publication EP 0 891 832 A1 serves as an example of such a drilling tool.

[0003] Such drilling tools (also simply called drill bits), such as the one described in publication EP 0 891 832 A1, have a shank, a working area, and a head. The shank serves to clamp the drill bit in a chuck (SDS chuck) of a suitable machine, such as a rotary hammer or a drill press. The working area has one or more spiral flutes that serve to remove drilling dust. The head is used to cut the hole. It is common practice to equip the head with a carbide insert. This reduces wear on the head.

[0004] To fasten an object to a wall made of masonry, concrete, reinforced concrete, or stone, it is known to use anchors that are provided with projections in a type of barb and are inserted into the drilled hole. A fastener, such as a screw or threaded rod, is then screwed into the anchor, thereby expanding its circumference. This causes the barbs to engage with the wall material, preventing the anchor from being pulled out.

[0005] Accordingly, the hole to be drilled (the bore) must be longer than the length of the anchor. Otherwise, the fastener cannot be screwed in in such a way that the anchor is sufficiently expanded. The length of the bore is also related to the diameter of the bore and / or the anchor.

[0006] However, it is also not advisable to make the bore so long that a large gap remains between the tip of the screwed-in fastener and the end of the bore. This leads to excessive wear of the drilling tool if the bore is made longer than necessary.

[0007] It is known that in standard drilling machines (e.g., drills or rotary hammers), a rod is positioned between the chuck and a handle of the machine. The longitudinal axis of this rod is parallel to the axis of rotation of the drill bit. The rod is designed to be movable towards the drill bit tip. This allows the length of the hole to be defined by bringing the tip of the rod into contact with the wall. The length of the hole then corresponds to the distance from the tip of the drill bit to the tip of the rod.

[0008] However, it is cumbersome to regularly adjust the rod length when drilling holes of different diameters, as different drilling lengths are then required. Furthermore, corresponding forces and moments act on the rod's mounting during drilling when it comes into contact with the wall. This can lead to shifts in the position of the rod tip and wear on the rod's mounting.

[0009] Document US 2004 / 052597A1 shows a drill bit whose drill grooves are formed in the form of facets. The facets and transitions are intended to create overpressure in the area of ​​the drill bit tip.

[0010] Document US 5 350 261 A1 relates to a drilling tool in which the core thickness decreases at a predetermined distance from the tip.

[0011] According to the publication FR 2 851 945 A1, a marking (or multiple markings) can be applied to a drilling tool. The marking is applied, for example, "by etching, painting, machining, laser marking, or any other suitable method." The marking is indelible when manufactured by laser engraving. When the marking is applied within the groove, it is protected against wear.

[0012] The purpose of the invention is to provide a drilling tool with an easy-to-use and reliable borehole length indicator.

[0013] The object of the invention is achieved by a drilling tool according to claim 1. Advantageous embodiments are carried out according to the dependent claims.

[0014] A drilling tool according to the invention has a shank, a working area, and a head with a tip. The working area has at least two grooves circumferentially around the tool axis. An indicator area is provided at a predetermined position in the working area, which is located at a predetermined distance from the tip of the head along a longitudinal axis of the drilling tool. The depth of the grooves in the indicator area differs from the depth of the grooves between the head and the indicator area, and from the depth of the grooves between the indicator area and the shank.

[0015] The indicator area stands out in depth compared to the depth of the grooves in the remaining working area. Therefore, the indicator area is visually detectable by the user during rapid rotation of the drill bit, such as occurs during drilling with a power drill (e.g., a hammer drill). The indicator area is clearly recognizable as a ring while the drill bit rotates. Even during hammer operation with, for example, an impact drill or a rotary hammer, where the drill bit is subjected not only to rotation but also to a back-and-forth motion along its longitudinal axis, the indicator area remains easily visible.

[0016] The drilling tool can advantageously have four circumferential grooves.

[0017] Advantageously, the slope of the helix angle of the circumferential grooves between the head and the shaft can change at least once.

[0018] It can be advantageous to change the slope at the indicator area.

[0019] According to the invention, the indicator area is produced by removing a cutting tool to manufacture the circumferential grooves over a predetermined length, whereby the indicator area has an increased core thickness.

[0020] Advantageously, the indicator area can have two indicator surfaces. A first indicator surface rises from the depth of the groove to the depth of the indicator area. The second indicator surface falls from the depth of the indicator area to the depth of the groove.

[0021] According to this design, the indicator area has a ramped, rising or falling slope. Therefore, the removal of drilling dust is easily possible without the risk of the dust accumulating and clogging the groove due to the reduced cross-section in the indicator area. Alternatively, the indicator area can be designed as a step.

[0022] Such a drilling tool is easier to manufacture.

[0023] Advantageously, the depth of the groove in the indicator area can be reduced to between 0.2 and 0.3 mm, preferably by 0.25 mm, and the length of the indicator area can be between 0.4 and 0.6 mm, preferably 0.5 mm.

[0024] A currently preferred embodiment of the invention is described with reference to the attached figures. The figures show: the Fig. 1 a top view of a drilling tool according to the invention; and the Fig. 2 a section labeled II of the Fig. 1 .

[0025] The drilling tool (hereinafter also referred to as drill bit) according to the embodiment has a shank 1 which serves to receive the drill bit in a holder of a machine. A commercially available drill, hammer drill, rotary hammer, etc., can be used as the machine. The one in the Fig. 1 The shaft shown as an example is designed for use in an SDS holder.

[0026] A working area 3 is formed adjacent to the shank 1, which is provided with four chamfers and spiral grooves 7 of a predetermined depth located between them. At an end opposite the shank in the longitudinal direction of the drill, a head 5 with a tip 5a is formed. The head 5 is made of a sintered material, which is joined to the material of the working area 3 by brazing.

[0027] A predetermined length from the tip 5a of the head 5 in the direction of the shaft 1, an indicator area 11 is formed in the grooves 7. At the indicator area 11, the cross-section of the grooves 7 is reduced by a decrease in the groove depth.

[0028] The indicator area 11 has two essentially rectangular indicator surfaces 11a and 11b. Indicator surface 11a forms a smooth transition from the head 5 to the shaft 1, from the depth of the groove 7 to the reduced depth of the groove 7 on the indicator area 11. The second indicator surface 11b forms a smooth transition from the head 5 to the shaft 1, from the reduced depth of the groove 7 on the indicator area 11 back to the depth of the groove 7.

[0029] This prevents removed material such as drilling dust or shavings from accumulating in the indicator area 11 and clogging the groove 7.

[0030] According to the exemplary embodiment, the grooves are formed by a machining process such as milling or grinding. To create the indicator area, the machining tool is raised slightly, e.g., by 0.25 mm, upon reaching the position of the indicator area and lowered again after traversing a predetermined length, e.g., 0.5 mm. This makes it possible to form an indicator area that is clearly visible as a ring.

[0031] The distance I between the tip 5a and the indicator area 11 corresponds to an ideal drilling depth for the diameter of the drilling tool. The ideal drilling depth is determined in relation to the diameter of a dowel to be inserted into the hole (such as a plastic expansion dowel) and the additional length of any part of a fastener, such as a screw or threaded rod, that extends beyond the dowel into the hole. For example, for dowel diameters between 4 and 20 mm, this additional length is between 5 and 30 mm, so the distance I between the tip of the head and the indicator area is the sum of the length of the dowel and this additional length.

[0032] Dowel manufacturers also provide tables from which these length specifications can be read for each available diameter.

[0033] A second preferred embodiment of the invention, which is not apparent from the figures, relates to a drilling tool like the one described above, with the modification that the helix angle of the flutes changes. According to the second embodiment, an indicator area corresponding to the indicator area 11 described above is located at the position where the helix angle of the flutes changes.

[0034] The drilling tool according to the second embodiment has grooves with a shallow pitch in the working area near the head. Drilling is therefore easier in this area, although the removal of drilling dust is slower. Near the shank, the working area again has grooves with a steeper pitch, resulting in improved removal of drilling dust in this area. The transition between the area with the shallow-pitch grooves and the area with the steeper-pitch grooves is located at a distance from the tip of the head corresponding to the ideal borehole length.

[0035] The indicator area according to the second embodiment is therefore arranged at this transition.

[0036] The invention has been described with reference to currently preferred embodiments. However, it should be noted that these embodiments serve only as examples and are not intended to limit the scope of the invention.

[0037] According to this embodiment, for example, the shank is provided with an SDS slot for insertion into an SDS drill chuck. Alternatively, the shank can also be designed differently, for example with a continuous round cross-section or a polygonal cross-section.

[0038] The drilling tool according to the embodiment is intended for machining masonry made of brick, stone, concrete, or reinforced concrete. However, an indicator area according to the invention can also be provided on a drilling tool intended for drilling wood or metal.

Claims

1. A drilling tool comprising: A shaft (1); a working region (3); and a head (5) with a tip (5a); wherein the working region (3) has at least two flutes (7) extending circumferentially around the tool axis; wherein at a predetermined position in the working region (3), which has a predetermined distance (I) from the tip (5a) of the head (5) along a longitudinal axis of the drilling tool, an indicator region (11), optically detectable at a rotation of the drilling tool, of an ideal borehole depth provided for the diameter of the drilling tool, is provided, in which the depth of the flutes (7) differs from the depth of the flutes between the head (5) and the indicator region (11) and the depth of the flutes between the indicator region (11) and the shaft (1), characterized in that the indicator region (11) is formed by lifting a cutting tool for machining the circumferential flutes (7) over a predetermined length, whereby the indicator region (11) has an increased core thickness.

2. The drilling tool according to claim 1, wherein the drilling tool has four circumferential flutes.

3. The drilling tool according to claim 1 or 2, wherein the incline of the helix angle of the circumferential flutes between the head and the shaft changes at least once.

4. The drilling tool according to claim 3, wherein a change in incline occurs in the indicator region.

5. The drilling tool according to one of the preceding claims, wherein the indicator region (11) has two indicator surfaces (11a, 11b), of which a first indicator surface (11a) slopes upwards from the depth of the flute (7) to the depth of the indicator region (11), and the second indicator surface (11b) slopes downward from the depth of the indicator region (11) to the depth of the flute.

6. The drilling tool according to any one of claims 1 to 4, wherein the indicator region is provided in the form of a step.

7. The drilling tool according to one of the preceding claims, wherein the depth of the flute (7) in the indicator region is reduced by between 0.2 and 0.3 mm, preferably by 0.25 mm.

8. The drilling tool according to one of the preceding claims, wherein a length of the indicator region (11) is between 0.4 and 0.6 mm, preferably 0.5 mm.