Combined ripping and chipping device for creating holes in a substrate

Abstract

Device (1) for forming a hole (202) in a substrate (200), the device (1) comprising: a rotationally drivable shaft section (9); and a plurality of material removal sections (15) extending radially from the shaft section (9) and rotatably drivable by the shaft section (9); wherein at least some of the material removal sections (15) have an external tearing device (5) for tearing off material of the substrate (200) for circumferentially defining the hole (202) in the substrate (200), and wherein at least some of the material removal sections (15) have a chipping device (13) arranged between the shaft section (9) and a radial outer side of the respective material removal section (15) for chipping away material of the substrate (200), wherein, starting from an outer material tear-off tip (300) of the tearing device (5), a curved material removal edge (302) of the tearing device (5) extends to a material removal edge (304) of the chipping device (13), wherein the material removal edge (302) of the tearing device (5) is curved in the direction of rotation (306) from an outer front end (308) of the respective material removal section (15) towards a further inner rear end (310) of the respective material removal section (15); wherein at least one rib (7) arranged between respective gaps (19) is provided on at least some of the material removal sections (15) in the region of the respective chipping device (13) for comminuting removed material; wherein at least some of the chip devices (13) and / or ribs (7) are arranged replaceably on at least some of the material removal sections (15); wherein the tearing device (5) is arranged at the front of the respective material removal section (15) in the direction of rotation (306).

Description

The invention relates to a device and an arrangement for forming a hole in a substrate and to a method for forming a hole in a substrate.There are milling cutters for making holes in lightweight concrete which mill along the circumference of the later hole. Milling cutters, however, cannot produce holes in thick lightweight concrete plates.There are also drills for making holes in lightweight concrete. Drills cut off the material of the lightweight concrete, as a result of which a hole is formed. However, drills do not usually produce a clean edge of the borehole, i.e. the borehole wall has unevenness.With regard to known devices, reference is made to the following publications: DE 86 23 584 U1, DE 29 52 295 A1, U.S. Pat. No. 4,294,319 A, DE 198 32 551 A1, DE 260 378 A, DE 10 2007 010 321 A1, DE 26 36 182 A1.It is an object of the present invention to make it possible to produce a hole in a substrate with a clean hole wall and with a depth that can be selected over a wide range.This object is achieved by the subject matters having the features according to the independent claims. Further embodiments are shown in the dependent claims.According to an exemplary embodiment of the present invention, a device for forming a hole in a substrate is provided, wherein the device has a shaft section that can be driven in rotation (for example with motor force and / or muscle force) and a plurality of material removal sections that extend from the shaft section (in particular in a wing-like manner) radially (in particular perpendicular to the axis of rotation) and can be driven in rotation by the rotating shaft section, wherein at least a part (i.e. one or more) of the material removal sections has an outer-side tearing device (in particular a tearing device forming the outer edge of a respective material removal section) for tearing off material of the substrate for circumferentially defining the hole (in particular for circumferentially defining the hole edge) in the substrate, and wherein at least a part (i.e. one or more) of the material removal sections has a machining device (arranged in the radial direction) between the shank section and a radial outer side of the respective material removal section for chip-removing material of the substrate.According to a further embodiment of the present invention, an arrangement for forming a hole in a substrate is provided, wherein the arrangement comprises at least one device having the features described above for forming a hole in a substrate and a drive device (i.e. an interface to the device with the capability of providing rotational energy) which is configured for receiving the shank section and for rotationally driving the device in the received state.According to yet another exemplary embodiment of the present invention, a method for forming a hole in a substrate is provided, wherein in the method a shank portion, from which a plurality of material removal portions co-rotating with the shank portion extends radially outwards, is rotationally driven, the hole in the substrate is defined by means of a respective outer-side tearing device on at least one of the material removal portions by means of tearing and tearing away material of the substrate in the circumferential direction, and (in particular after the tearing) material of the substrate is chip-removed by means of at least one respective machining device arranged between the shank portion and a radial outer side of the respective material removal portion (wherein the radial outer side can in particular be formed by the respective tearing device).According to an exemplary embodiment of the present invention, an easily operated tool for producing a hole in a substrate is provided, in which a clean circular ring can be formed in the substrate first by means of radially outside scribing of the substrate with scribing devices in the outer region of a plurality of rotor-like material removal sections, the outer edge of which ring is well-defined circumferentially by the scribing and scribing of surface material of the substrate. By means of machining of machining devices arranged at the central location of some or all of the material removal sections, material of the underlying surface in the ring interior can then be machined, scraped or cut off. In this way, even very deep holes can be formed in the subgrade, since the tearing and machining can in principle be continued axially for any length.According to an exemplary embodiment of the present invention, it is thus possible to create a principle of drilled holes of any desired depth with a clean drilled hole wall. A quick change of the chip device or cutting tool adapted to a desired borehole diameter is conveniently possible. In the device, a tearing device, for example designed as a milling cutter (for cutting / tearing along the circumference of the borehole), is combined with a cutting device, for example designed as a cutting edge (for lifting off the material of the substrate by cutting, for example lightweight concrete). With the described concept, a clean cut surface is available even when hole formation is sought in challenging subsurfaces (e.g., an I-block 90 containing a tough coating of a Styropor® cement mixture). This makes it possible to easily create penetrations. Furthermore, a rapid change of the material removal sections or of components thereof with holes to be formed with different diameters is possible. The penetration can be produced without settling or interrupting the hole-forming process, since the described device is not impaired in its functioning by the ablated material produced in the hole. Commercially available drive devices (for example cordless screwdriver, drilling machine) can be used for receiving and rotationally driving the device.Additional exemplary embodiments of the device, the arrangement and the method are described below.According to an exemplary embodiment, at least a part of the (in particular each of the) material removal sections can have the outside tearing device for tearing off material of the base for circumferentially defining the hole in the base and a machining device arranged between the shank section and the tearing device for machining off material of the base. Thus, if each of the material removal sections has a tearing device and a cutting device, a particularly uniform force distribution over the entire device is ensured during operation and the occurrence of imbalance or transverse forces is particularly effectively suppressed. However, structural separation of tearing devices and cutting devices is also possible. For example, there may be one or more material removal sections that have only one tearing device but no cutting device. Furthermore, there may be one or more material removal sections which have only one cutting device but no tearing device. Finally, there may be one or more material removal sections which have both a tearing device and a cutting device.According to an exemplary embodiment, the shank portion can have a drive region, in particular a drive end, on which a drive, in particular a hexagon, is provided, which is designed to be engaged by a drive device in order to rotationally drive the shank portion. Other drives are also possible, for example a shaped recess (for example a longitudinal slot, a cross slot, a Torx drive, an AW drive or another groove) in an end face of the shank section as a drive region, into which a drive tool such as, for example, an cordless screwdriver can engage. In this way, it is possible to use the device according to the invention with conventional drive devices, such as an cordless screwdriver or a drilling machine.According to an exemplary embodiment, the shank portion can have a mounting region, in particular a mounting end (which can be arranged at an end of the shank portion opposite the drive end), on which the material removal portions are arranged in particular in a removable manner. This allows a selective exchange of the individual material removal sections, for example in the case of their wear, with little maintenance effort.According to an exemplary embodiment, the device can have a centering pin which can extend along an axis of rotation of the shank portion and axially beyond the material removal portions in such a way that the centering pin, when forming the hole, first rests on the underlying surface before the material removal portions rest on the underlying surface. According to a corresponding exemplary embodiment, during the method, the centering mandrel, which extends along the axis of rotation of the shank portion and axially beyond the material removal portions, can be placed on the planar base during the formation of the hole before the circumferential tearing is started. The centering pin can serve on the one hand as a mechanical guide during the formation of the hole, the position of which can be precisely fixed as a result. The centering pin can also serve, however, to be placed on a recorded target point on the surface of the substrate in order to serve as an orientation aid for a user.According to an exemplary embodiment, the centering mandrel can be formed simultaneously to the fastening of the material removal sections to the shank section. For example, a plurality of material-removing sections (for example, designed as a common body, which can also be referred to as a drill head) can be placed on a mounting end of the shank section in order to be able to be fastened there by means of subsequent screwing on of the centering mandrel for clampingly fastening the material-removing sections between the shank section and the centering mandrel.According to an exemplary embodiment, the shank portion can have a mandrel receptacle (in particular close to the mounting region of the shank portion), in which the centering mandrel can be received in a removable manner. The centering pin can thus also be provided in an exchangeable manner. For example, in the event of wear or the need to attach another mandrel (for example, in terms of one of its length), this may be advantageous.According to an exemplary embodiment, the centering mandrel can have at its free end a drilling device (for example a drill bit with one or more drill bits) for drilling into the ground. In this case, the centering pin can perform a drilling function and in turn contribute to the material removal during the formation of the hole in the underlying surface. Such a central hole, which the centering mandrel can form, can then significantly improve the guidance of the device in the hole during the preliminary operation.According to an exemplary embodiment, the plurality of material removal sections can be arranged spatially symmetrically (in particular axis-symmetrically or point-symmetrically) around the shank section. If the material removal sections are arranged symmetrically around the shank section, a symmetrical load is also introduced into the rod assembly or the shank section, thus avoiding undesired imbalance.According to an exemplary embodiment, the plurality of material removal sections can be arranged opposite one another in pairs around the shank section. Two opposing material removal sections can thus each be aligned running along a common extension direction. As a result, a particularly symmetrical introduction of force into the underlying surface and a uniform loading of different material removal sections can be achieved, since material removal sections located opposite one another in each case can generate or absorb counter-forces which are inverse to one another. This suppresses undesired slipping of a user during the formation of the hole due to acting uncompensated forces. The transverse forces or torques to be absorbed by the drive device and / or the user are then likewise low.According to an exemplary embodiment, exactly four material removal sections can be arranged around the shank section. In its visual appearance, this can be similar to the rotor of a helicopter. This has proven to be particularly symmetrical and advantageous with regard to the acting forces. Other preferred embodiments use two, three, five, six or more material removal portions around the shank portion.According to an exemplary embodiment, the material removal sections can be configured (in particular arranged spatially relative to one another) such that, when forming the hole in the substrate, the tearing devices initially tear the substrate circumferentially before the cutting devices begin the material removal of the substrate by machining. According to a corresponding exemplary embodiment, circumferential tearing can be started in time in the method by placing it on a planar base before machining is started. For example, all the tearing tips or tearing edges of the material removal sections can lie on a common plane. Furthermore, all chip edges of the material removal sections can lie on a common plane which can be oriented in particular parallel to the plane of the tearing tips or tearing edges and can be spatially set back with respect to this plane with respect to a hole generation direction. The subsequent chronological subsequent switching of the cutting / cutting central material removal with respect to the tearing / milling edge removal can thus be achieved in that the effective ends of the tearing sections extend axially further in the direction of the underlying surface than the effective surfaces of the cutting devices. It has been found that after a clean definition of a hole circumference by the tearing sections, an efficient material removal by the machining devices up to an approximately freely selectable desired depth is subsequently possible.According to an exemplary embodiment, each of the material removal sections can extend radially outwards from the shank section to the same extent. This in turn produces very symmetrical force conditions. Moreover, by cooperation of all tear sections, a particularly precise definition of the hole circumference is thus made possible.According to an exemplary embodiment, at least a part of the tearing devices can have a tear tooth which has a steep, in particular vertical, tear edge (in particular a milling edge) at an outer end, which tear edge is adjoined by a surface which is concavely curved in the radial direction towards the shank portion. As a result, circular cylindrical holes can be produced to a very good approximation, the outer diameters of which holes are predetermined by the steep outer edge of the tear teeth. The concavely curved surface serves for the efficient removal of removed material of the underlying surface and also produces a smooth transition to the chip device located radially further inward (in particular to a chip edge thereof).According to an exemplary embodiment, in the device at least a part of the material removal sections can have at least one additional tearing device, which is arranged between the tearing device and the shank section in the radial direction. It may be useful to provide multiple tearing teeth per material removal section along the radius, and not just one at the end.According to an exemplary embodiment, starting from an outer material tearing tip of the tearing device, a curved material removal edge of the tearing device can extend as far as a material removal edge, in particular at least sectionally straight, of the machining device. The material tear-off tip forms a tear-off groove along the circumference of the hole to be formed in the substrate when the device is rotated. The curved material removal edge then produces a homogeneous or continuous transition to a straight material removal edge of the machining device. This gentle transition prevents force peaks or jamming between the device and the material of the substrate. The straight chip edge, which is at least partially (in particular interrupted only by optional gaps for improving the material discharge properties), chips off material of the underlying surface over a large space and in a uniform manner in the central region of the substantially cylindrical hole.According to an exemplary embodiment, the material removal edge of the tearing device, in relation to a direction of rotation of the material removal section, can be curved from an outer front-side end of the respective material removal section towards a further inner rear-side end of the respective material removal section (wherein in the radial direction from the outside to the inside the curvature can be a left-hand curvature). Illustratively, a material removal edge of the tearing device formed in this way scoops material removed or torn off away from the tear-off position when the device is driven in rotation. In other words, the material removal edge of the tearing device can have such a cut and such a bevel that a circular shape of the hole formed is obtained during the rotation and there is no accumulation of material of the substrate to be transported away due to the blade effect.According to an exemplary embodiment, at least one rib arranged between two respective gaps for crushing material that has been ground can be provided on at least one part of the material removal sections in the region of the respective machining device. If one, two, three or more ribs are formed on a respective chip section by interrupting a continuous chip edge by a radial sequence of gaps, the ribs can cut material in a milling manner, which is then transported away with the help of the gaps. Interrupting a continuous chip edge by means of the gaps to form the ribs reduces the contact surface or contact edge length between the substrate and the chip device, so that locally higher forces can be transmitted to the substrate and also a lower resistance acts, which improves the removal results. At the same time, the recesses in the form of the gaps lead to improved removal of the removed material.According to an exemplary embodiment, at least a part of the machining devices or of the ribs can be attached to at least a part of the material removal sections in an exchangeable manner. These components of the device which are exposed to particularly strong mechanical stress and are therefore susceptible to wear can thus be isolated or exchanged separately from other components. Components of the device that are less susceptible to wear then do not have to be exchanged together unnecessarily, which is advantageous for reasons of sustainability and resource conservation.According to an exemplary embodiment, the device can comprise or consist of steel (in particular also stainless steel), plastic, tungsten carbide and / or diamond composites. Particularly hard materials such as tungsten carbide or diamond composites can be selectively deposited on certain components of the device which are exposed to particularly high forces during operation. These include the sharp-edged sections of the tearing means and the sharp-edged sections of the cutting means.According to an exemplary embodiment, the arrangement can have at least one further device with the features described above, the shank portion of which can alternatively be received by the drive device, wherein a radial span of the material removal portions of the at least one further device differs from a radial span of the material removal portions of the previously described device in order to form holes of different diameters. In particular, in an arrangement according to an exemplary embodiment, a set of devices may be provided, each of which may differ from the respective other devices with respect to the diameters of the hole to be formed. As a result, a wide range of hole sizes can be produced, wherein in each case one apparatus can be placed on one and the same drive device.According to an exemplary embodiment, the arrangement can have at least one further plurality of material removal sections with the above-mentioned features, which can be mounted on the shank section of the device instead of the plurality of material removal sections described hitherto, wherein a radial span of the further material removal sections differs from a radial span of the material removal sections in order to form holes of different diameters. The further plurality of material removal sections can be formed as a common body, which can also be referred to as a drill head. According to the described embodiment, for forming holes of a different diameter, it is possible to replace not the entire device but only the material removal sections and thereby use the same shaft section as previously. This leads to a particularly compact configuration of the arrangement.According to an exemplary embodiment, the drive device can be designed as an cordless screwdriver or drilling machine. Advantageously, such conventionally available cordless screwdrivers or drilling machines can be used as such and do not have to be adapted to the device according to the invention. The latter, however, should have a drive (for example a hexagon or a suitably shaped drive groove) which is compatible with the drive device.According to an exemplary embodiment, a blind hole or a through hole can be formed as a hole in the base. The depth of the object hole or the pallet of substrates of different thicknesses, for the complete penetration of which the device can be used, is large on account of the hole-producing principle according to the invention.According to an exemplary embodiment, light concrete, porous concrete and / or Styropor® can be used as the worked subgrade, for example. The device according to the invention has proven to be particularly well suited for drilling a clean hole in a substrate made of a Zement-Styropor® mixture with a tough surface coating (in particular in an I-block 90, i.e. a fire protection component). In an I-block 90 or other fire protection component, tough surface coatings can cover a core that is sufficiently mechanically strong and resistant to fire. According to an exemplary embodiment of the device, the tearing devices thereof can first scribe the tough surface coating or penetrate it, before the core is removed by means of the cutting devices in terms of center of gravity. For fire protection reasons, the tough surface coating must be recoating unless a clean hole with a well-defined edge can be produced. However, the latter is possible exactly according to an exemplary embodiment, so that a complicated aftercoating can be avoided.According to exemplary embodiments, individual components of the device are individually replaceable, for example, in the event of wear or for adaptation to a specific hole-producing task (for example, for adaptation to a desired hole diameter, for hardness and / or type of the substrate, etc.). For example, a drill head that combines all material removal sections in one piece can be replaced as a whole. Alternatively, individual material removal sections can also be exchanged individually. Furthermore, it is possible to exchange individual components of the material removal sections, for example individual cutting devices, individual ribs, etc. separately. A centering mandrel may be exchanged separately from other components of the apparatus to adapt to specific tasks.Exemplary embodiments of the present invention are described in detail below with reference to the following figures. FIG. 1 shows a device mountable on a drive device for forming a hole in a substrate according to an exemplary embodiment of the invention. FIG. 2 shows two devices mountable on the same drive device with different outer diameters for forming respective holes in a lightweight concrete subgrade according to another exemplary embodiment of the invention. FIG. 3 shows an enlarged region of a material discharge section of the device according to FIG. 2.Identical or similar components in different figures are provided with identical reference numerals.FIG. 1 shows a device 1 for forming a hole in a substrate (see FIG. 2 for this purpose) according to an exemplary embodiment of the invention.The device 1 has a shank section 9 which can be driven in rotation by means of a drilling machine or an cordless screwdriver (not shown) and four material removal sections 15 which extend radially rigidly from the shank section 9 and can be driven in rotation by the rotating shank section 9. Two of the four material removal sections 15 each point in mutually opposite directions or are situated opposite one another, so that the four material removal sections 15 are arranged completely symmetrically to one another along the circumference. This makes it possible to avoid transverse forces and imbalance during penetration of the device 1 into the substrate, which could interfere with the homogeneity of the hole formed. Each of the material removal sections 15 has an outside tearing device 5, which is designed here as a sharp-edged tear tooth, for circumferential circular scribing of a surface of the underlying surface at the beginning of the formation of the hole. In this case, the co-rotating tearing device 5 tears material out of the underlying surface in order to spatially delimit and initiate the hole formation. By circumferential scribing of the substrate by means of all four tearing devices 5 arranged on identical radii, a clean vertical hole wall without frays is simultaneously defined. In the radial direction between the shank portion 9 and each of the four tearing devices 5, a respective sharp-edged cutting device 13 for the cutting removal of material of the substrate is provided on each of the material removal portions 15. When the apparatus 1 is rotated, the chip devices 13 are used to remove material in the radial central region of the hole and thus to successively recess the hole up to a predeterminable final depth. For this purpose, a user simply needs to place the rotating device 1 at the desired location on the surface of the substrate under light pressure.The shank portion 9 carries the material removal portions 15 in a central region (see reference sign 17) and has a drive region 11 at a first end. On the drive region 11, a drive designed here as a hexagon is provided. This can be engaged by an engagement section of a drive device, in particular by a chuck of a drilling machine (or, if the drive is formed as a groove in an end face of the shank section 9, a screw tip of an cordless screwdriver), in order to rotationally drive or rotate the shank section 9 by means of the drive device for hole formation. The shank portion 9 extends along the axis of rotation of the device 1. the shank portion 9 has in its central portion a mounting region 17 on which the material removal portions 15 are arranged in a removable manner. As a result, individual material removal sections 15 can be replaced with little effort, for example during wear.The device 1 further comprises an optional centering mandrel 3 which, adjacent to the mounting region 17, likewise extends along the axis of rotation of the shank portion 9 and axially beyond the material removal portions 15. In other words, the centering mandrel 3 is aligned along the axis of rotation with the shank section 9. the centering mandrel 3 has such a length and protrudes axially beyond the material removal sections 15 to such an extent that, when forming the hole, the front-side end tip of the centering mandrel 3 rests on the underlying surface before the material removal sections 15 rest on the underlying surface. In this way, the centering pin 3 serves as a position marker which can be placed, for example, on a corresponding marking of a surface of the substrate which describes the center of the hole to be formed. Furthermore, the centering pin 3 serves as a guide when forming the hole, in that it penetrates with its tip ever further into the underlying surface when an axial pressure is exerted.The shank portion 9 has a mandrel receptacle in which the centering mandrel 3 can be received in a removable manner. In the event of wear or the need to mount a centering mandrel 3 of a different configuration (for example of a different length or else with a drill bit) on the apparatus 1, a desired centering mandrel 3 can be screwed on or off the mandrel receptacle, for example, for which purpose the centering mandrel 3 can have an external thread and the mandrel receptacle can have an internal thread.The material removal sections 15 are configured such that, when forming the hole in the substrate, the tearing devices 5 initially cut or mill into the substrate in a tearing manner, before the cutting devices 13 begin the cutting removal of material of the substrate (cutting and / or milling according to their configuration). This is achieved in that the tearing devices 5 extend further in the hole-producing direction towards the underlying surface than the cutting devices 13. The centering pin 3 extends further in the hole-producing direction towards the underlying surface than the tearing devices 5.It can also be seen in FIG. 1 that ribs 7 for crushing material that has been ground are provided on the material removal sections 15 in the region of the respective machining device 13, which ribs are formed between respectively adjacent pairs of recesses or gaps 19. The sharp-edged ribs 7 remove material from the substrate, which material can be transported away at least partially through the gaps 19. By effectively shortening a sharp removal edge by forming the gaps 19 to produce the ribs 7, the torque acts on the substrate along a shorter area or edge area when the device 1 rotates, which reduces the mechanical resistance during the formation of the hole and reinforces the force effect on the surface sections of the substrate that are operatively connected to the ribs 7.The machining devices 13 or the ribs 7, on which a particularly large mechanical load acts during operation of the device 1, can be arranged interchangeably on the respective material removal sections 15.The device 1 can comprise steel (in particular stainless steel) or consist thereof, wherein particularly highly stressed components (such as, for example, the tearing device 5 or the ribs 7) can be locally hardened, for example, by means of tungsten carbide or diamond composites or by means of other measures.The device 1 designed as a lightweight concrete milling cutter for producing penetrations in lightweight concrete thus comprises the centering mandrel 3 for positioning the drilling center. A respective tear tooth as a tear device 5 is provided for clean coating trimming of the lightweight concrete on the surface thereof. The ribs 7 serve for comminution of the drill material and cutting devices 13 designed as cutters serve for the cutting lifting of the lightweight concrete. A guide rod, which forms the shank portion 9, serves for guiding the device 1 in the underlying surface. A hexagonal receptacle constitutes the drive 11 and is designed for connection to an cordless screwdriver or a drilling machine. The ribs 7 or machining devices 13 are seated on a respective carrier as material removal section 15. A carrier head, which forms the mounting section 17, is designed to receive the material removal sections 15. The centering pin 3 is held in a receptacle and designed to be replaceable, for example screwed on.FIG. 2 shows two devices 1 with different outer diameters that can be mounted on the same drive device (not shown) for forming respective holes 202 in a base 200 made of lightweight concrete according to another exemplary embodiment of the invention.The substrate 200 according to FIG. 2 is a fire protection component and has a core 210 in the form of a composite material made of cement and Styropor®. The core 210 is covered with a cover layer 212 which contributes to fire protection and has tough material properties. For reasons of fire protection, it is essential to generate a clean transition when forming a hole in the base 200 at a boundary between the hole 202 and a region of the base 210 that is not to be removed, in particular as regards the cover layer 212. For this purpose, the two devices 1 shown in FIG. 2 are particularly predestined.As shown in FIG. 2, a device 1 designed as a lightweight concrete milling cutter can be used for producing holes 202 as penetrations in a substrate 200, such as an I-block 90. The maximum drilling depth of the device 1 is limited only by the essentially freely selectable length of the guide rod or shank section 9. In order to establish a penetration as a hole 202 in a subgrade 200 designed as lightweight concrete, the centering tip of the centering pin 3 is positioned suitably on the lightweight concrete. The material removal sections 15 are configured such that their length is adapted to the desired borehole diameter. The lightweight concrete milling cutter is connected to a drive tool, for example to a drilling machine, i.e. the drive 11 designed as a hexagonal receptacle is inserted into the drilling machine and is fixed there in a suitable manner. Subsequently, the lightweight concrete milling cutter is set in rotation by the drilling machine. The centering tip penetrates further into the lightweight concrete. At some point, the milling cutters 5 are placed on the lightweight concrete and mill the periphery of the borehole. As the process continues, the cutting devices 13 configured as cutters are placed on the lightweight concrete and lift it off in a cutting manner. Rotation is continued under axial pressure on the device 1 until the hole 202 is made to the appropriate depth. This may be a complete penetration of the lightweight concrete. However, it is alternatively possible to also produce a blind hole with the lightweight concrete milling cutter.To adapt to another borehole diameter, the centering mandrel 3 is unscrewed and the drill head (comprising the machining devices 13 / ribs 7 designed here as cutters and the tearing devices 5 on the carrier, which is four-rotor here, in the form of the material removal sections 15) is removed from the carrier head or mounting section 17. A desired drill head is then placed on the mounting section 17 and fixed there, for example by screwing on the centering mandrel 3. However, it is alternatively possible to mount a drill head on the mounting section 17 or to disassemble it therefrom without the participation of the optional centering pin 3 being required in this case. For this purpose, a releasable latching mechanism or a screw connection between the drill head and the mounting section 17 can be implemented, for example.The drive 11 of the device 1 can be a hexagon (depending on its size) or simply a cylindrical section, so that it can be used in conjunction with an cordless screwdriver or a power drill with a chuck. Examples are SDS and SDS293 (Special Direct System) recordings. In the present case, the lightweight concrete milling cutter has four material removal sections 15, as a result of which good drilling results are achieved. However, fewer or more material removal sections 15 can also be used, for example three or five, wherein a symmetrical arrangement of the material removal sections 15 is preferred, however, in order to achieve good drilling results. Depending on the field of use of the lightweight concrete milling cutter, individual components thereof can be manufactured from materials other than steel or stainless steel. If the lightweight concrete milling cutter is to be used only for the penetration of Styropor® for example, it may be sufficient if some or all of the parts are made of plastic. If the lightweight concrete milling cutter is also to be used for harder materials, it is possible to produce individual or all parts (for example the cutters and / or the milling cutters) from harder materials than stainless steel, for example from tungsten carbide or with diamond coating, etc.The centering tip or centering mandrel 3 can be adapted to the type of material of the substrate. If a hard material is to be penetrated, the centering mandrel 3 can have a small diameter and a small axial length, so that the centering mandrel 3 serves only for placing the lightweight concrete milling cutter. If a soft material is to be penetrated, the centering pin 3 can have a larger diameter and a larger axial length, in order that a sufficient stability thereof is provided for the drilling process. The centering pin 3 itself can be designed as a drill.The machining devices 13 or the ribs 7 can be arranged removably on the material removal section 15, which is referred to as carrier, in order to be able to exchange these individually when they are worn out.The I-block 90 has been specified as the material or substrate to be processed. However, other materials are also possible, for example Styropor@ slabs, porous concrete and porous lightweight concrete, etc.With appropriate dimensioning of the beam, the lightweight concrete milling cutter can also be used for producing blind holes for electrical installation. Conventionally, a hollow drill has to be set twice when two UP cans are to be placed one below the other. With a device 1 according to an exemplary embodiment, a larger (for example twice) can depth can be drilled in one operation.FIG. 3 shows an enlarged region of one of the material removal sections 15 of the device 1 according to FIG. 2.As can be seen from FIG. 3, proceeding from an outer material tearing tip 300 of the tearing device 5, a material removal edge 302 of the tearing device 5, which is curved to the left in the inward direction, extends as far as a sectionally straight material removal edge 304 of the machining device 13. This allows efficient scribing of the edge of the hole 202, efficient material removal in the central region and efficient removal of the removed material.In addition, it should be noted that "having" does not exclude other elements or steps and "a" or "an" does not exclude a plurality. It should also be noted that features or steps that have been described with reference to one of the above exemplary embodiments can also be used in combination with other features or steps of other exemplary embodiments described above. Reference signs in the claims should not be regarded as limiting.

Claims

Device (1) for forming a hole (202) in a substrate (200), wherein the device (1) comprises: a rotationally drivable shaft section (9); and a plurality of material-removing sections (15) extending radially from the shaft section (9) and rotationally drivable by the shaft section (9); wherein at least a part of the material-removing sections (15) comprises an external tearing device (5) for tearing off material of the substrate (200) for circumferentially defining the hole (202) in the substrate (200), and wherein at least a part of the material-removing sections (15) comprises a machining device (13) arranged between the shaft section (9) and a radial outer side of the respective material-removing section (15) for chip-removing material of the substrate (200), wherein, starting from an outer material tearing tip (300) of the tearing device (5), a curved material removal edge (302) of the tearing device (5) extends as far as a material removal edge (304) of the machining device (13), wherein the material removal edge (302) of the tearing device (5) is curved in the direction of rotation (306) from an outer front end (308) of the respective material removal section (15) towards a further inner rear end (310) of the respective material removal section (15); wherein at least one rib (7) arranged between respective gaps (19) for crushing removed material is provided on at least one part of the material removal sections (15) in the region of the respective machining device (13); wherein at least one part of the machining devices (13) and / or ribs (7) is arranged interchangeably on at least one part of the material removal sections (15); wherein the tearing device (5) is arranged at the front of the respective material removal section (15) in the direction of rotation (306).Device (1) according to claim 1, wherein the shaft section (9) has a drive region (11), in particular a drive end, on which a drive, in particular a hexagon, is provided, which is configured to be engaged by a drive device in order to rotationally drive the shaft section (9).Device (1) according to claim 1 or 2, comprising a centering pin (3) which extends along an axis of rotation of the shank portion (9) and axially beyond the material removal portions (15) in such a way that the centering pin (3) rests on the substrate (200) during the formation of the hole (202) before the material removal portions (15) rest on the substrate (200).Device (1) according to claim 3, wherein the shaft section (9) has a mandrel receptacle in which the centering mandrel (3) can be received in a removable manner.The device (1) according to claim 3 or 4, wherein the centering mandrel (3) has a drilling device at a free end for drilling into the subgrade (200).The device (1) according to any one of claims 1 to 5, wherein the plurality of material removal portions (15) are arranged symmetrically around the shaft portion (9).The device (1) according to any one of claims 1 to 6, wherein the plurality of material removal sections (15) are arranged opposite each other in pairs around the shaft section (9).Device (1) according to one of Claims 1 to 7, wherein exactly four material-removing sections (15) are arranged around the shank section (9), in particular with a mutual angular offset of 90° in each case.Device (1) according to one of Claims 1 to 8, wherein each of the material-removing sections (15) extends radially outwards to the same extent starting from the shank section (9).Device (1) according to one of claims 1 to 9, wherein at least a part of the tearing means (5) has a tear tooth which has a steep, in particular vertical, tear edge at an outer end, wherein the tear edge adjoins a surface which is concavely curved in the radial direction towards the shank portion (9).An assembly for forming a hole (202) in a substrate (200), the assembly comprising: a device (1) according to any one of claims 1 to 10 for forming the hole (202) in the substrate (200); and a drive device configured to receive the shaft portion (9) and to rotationally drive the device (1) in the received state.Arrangement according to Claim 11, having at least one further plurality of material removal sections (15) according to one of Claims 1 to 14, which can be mounted on the shank section (9) instead of the plurality of material removal sections (15), wherein a radial span of the further material removal sections (15) differs from a radial span of the material removal sections (15) in order to form holes (202) of different diameters.Arrangement according to one of Claims 11 to 12, wherein the drive device is designed as an cordless screwdriver or drilling machine.Method for forming a hole (202) in a substrate (200) by means of a device according to one of Claims 1 to 10, wherein the method comprises: rotationally driving a shank portion (9) from which a plurality of material-removing portions (15) co-rotating with the shank portion (9) extend radially outwards; tearing off material of the substrate (200) in order to define the hole (202) in the substrate (200) circumferentially by means of a respective outer-side tearing device (5) from at least one of the material-removing portions (15); Machining removal of material of the substrate (200) by means of at least one machining device (13) arranged between the shank portion (9) and a radial outer side of the respective material removal portion (15), wherein proceeding from an outer material tearing tip (300) of the tearing device (5) a curved material removal edge (302) of the tearing device (5) extends as far as a material removal edge (304) of the machining device (13), wherein the material removal edge (302) of the tearing device (5) is curved in the direction of rotation (306) from an outer front end (308) of the respective material removal portion (15) towards a further inner rear end (310) of the respective material removal portion (15).The method according to claim 14, wherein as the hole (202) in the substrate (200), one of the group consisting of a blind hole and a through hole is formed.The method of claim 14 or 15, wherein the hole (202) is formed in a subgrade (200) from a group consisting of a Zement-Styropor® mixture having a tough surface coating, lightweight concrete, porous concrete, and Styropor®.

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