Drill motor for a drill bit, tool holder for a drill bit, and drill bit
Patent Information
- Application Number
- AE202602523
- Authority / Receiving Office
- AE · AE
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-09-30
- Filing Date
- 2025-01-31
Smart Images
Figure ABST_ABST
Abstract
Description
DRILL MOTOR FOR A DRILL BIT, TOOL HOLDER FOR A DRILL BIT, AND DRILL BITThe present invention relates to a drill motor for a drill bit, wherein the drill bit has a connection for the drill motor, the connection being formed by a tubular section having an external profile on the outside and an internal thread on the inside, wherein the drill motor has a rotary drive with a shaft, the shaft having a projection with a tool holder, an external thread connectable to the internal thread of the drill bit being provided on the projection. Furthermore, the invention relates to a tool holder for a drill bit, the drill bit having a connection for the tool holder, the connection being formed by a cylindrical section having an external profile on the outside and an internal thread on the inside, the tool holder comprising an external thread connectable to the internal thread of the drill bit, the tool holder having a sleeve, the sleeve having a polygonal internal profile corresponding to the external profile. In addition, the invention relates to a drill bit and a set composed of a drill motor and a drill bit. BACKGROUND TO THE INVENTION A drill bit is a tool for drilling through very hard materials such as concrete, stone, metal, or combinations thereof. The drill bit typically consists of a metal cylinder which, on one side, is closed by an end cap with a connection for a drill motor and, on the open side, has a cutting edge usually equipped with a cutting trim. The cutting trim typically consists of cutting elements made of sintered steel with an admixture of industrial diamond, with the cutting trim being soldered or welded onto the metal cylinder. Diamond drill bits are particularly effective as diamonds are extremely hard. The cutting edge of the drill bit has several cutting elements shaped in such a way that they can efficiently cut through concrete. These cutting elements are designed such that they cut and crush the concrete as the bit rotates. The drill bit may exhibit channels or openings which remove the drilling dust emerging during drilling or, respectively, the drilling mud produced with water therefrom. This prevents the drill bit from becoming clogged and overheating. The drill bit is connected to a drill motor, with a connection being provided for this purpose on the back of the drill bit, and a tool holder being provided on the drill motor. Typically, the tool holder has an external thread (usually a drill spindle of 1 1 / 4") and the connection has a corresponding internal thread so that a threaded connection is established between the drill bit and the drill motor. The drill bit must be securely and stably connected to the drill motor to ensure precise drilling. A loose connection can lead to an imprecise drill hole, increased wear on the drill bit, and the drill bit detaching from the drill motor, posing a safety risk. Even during normal operation of the drill motor comprising a drill bit, the threaded connection is tightened more and more during drilling. Particularly when drilling into reinforced concrete, the rotational movement of the drill bit can experience a sudden deceleration as the drill segments engage the reinforcement, which may result in almost unsolvable jamming of the threaded connection. Said jamming can often only be resolved by cutting up the threaded connection, resulting in the drill bit's connection being destroyed. The drill bit is then unusable and must be disposed of, even though the drill segments would allow continued use. EP 3 854 988 A1 discloses a tool coupling in the form of a two-part adapter for coupling and decoupling a drill bit. EP 0 235 581 A1 shows a drill motor that can be connected to a drill bit by means of a bayonet lock. An adapter for attaching a drill bit to a drill motor is disclosed in DE 297 03 692 U1. BRIEF DESCRIPTION OF THE INVENTION With a practical application of the drill bit and the drill motor, the threaded connection of the prior art poses the risk of premature unusability of the drill bit if the connection between the drill bit and the drill motor can no longer be broken. It is the object of the present invention to redesign the described connection between the drill motor and the drill bit to avoid jamming of the threaded connection. In particular, the drill bit should still be easy to install on the drill motor, while it is possible to dismantle the drill bit from the drill motor even in the event of the drill bit becoming stuck in the material to be drilled, without destroying the drill bit. This object is achieved bya drill motor for a drill bit,the drill bit having a connection for the drill motor, the connection being formed by a tubular section having an external profile - that is preferably polygonal - on the outside and an internal thread on the inside,the drill motor having a rotary drive with a rotatable shaft,the shaft having a tool holder,the tool holder comprising an external thread connectable to the internal thread of the drill bit,characterized in that the tool holder has a sleeve concentrically surrounding the shaft,the sleeve having an internal tool section designed to be form-fitting with the external profile of the drill bit,the drill motor having a releasable locking device by means of which the sleeve can be coupled to the shaft and decoupled from the shaft. Unlike in the prior art with a purely threaded connection, in the present case, a sleeve is additionally provided on the tool holder, the sleeve having an internal tool section designed to be form-fitting with the external profile of the drill bit. This internal tool section can furthermore be engaged with the external profile of the drill bit. Normally, the external profile of the drill bit serves only for loosening the threaded connection or for establishing the threaded connection between the connection and the tool holder using a wrench. Therefore, the external profile of the drill bit is often an external hexagonal section. In the prior art, the power transmission occurs from the shaft to the drill bit via the threaded connection. According to the invention, the power transmission mainly occurs via the sleeve on the drill motor and the external profile on the drill bit, with the internal tool section and the external profile being in contact. In this case, the threaded connection primarily serves for stabilizing the smooth rotation of the drill bit on the shaft, but not for power transmission. When attaching the drill bit to the drill motor, the locking device is first positioned such that it is coupled to the gear housing and the sleeve is thus no longer rotatable. The external thread of the tool holder remains rotatable and can therefore be screwed into the internal thread of the drill bit. In this case, the stationary sleeve serves as a fixed bearing, and thus the shaft screws itself into the internal thread of the drill bits. The maximum tightening torque between the shaft and the drill bit is mechanically limited by the drill motor. Once the threaded connection between the internal thread of the drill bit and the external thread of the tool holder is established, the locking device is coupled as well, by means of a coupling element, for example. The power transmission from the drill motor to the drill bit occurs exclusively via the sleeve. It is thus the function of the locking device to couple or, respectively, decouple the rotational movements of the sleeve and of the drill bit, depending on the operating state. The internal tool section, which is designed to be form-fitting with the external profile of the drill bit, is replicated from a ring wrench in terms of its function. In one area of the shaft, the sleeve is positioned concentrically to the shaft, and it has a radial distance between the tool holder and the shaft. The internal tool section typically has a profile arranged in an annular fashion, which matches the external profile of the drill bit in a form-fitting manner. In many cases, the external profile of the drill bit comprises a straight, cylindrical section with a polygon for a cross-section, such as, e.g., an external hexagonal section. Therefore, the internal tool section is designed appropriately as a cylindrical sheath having a form-fitting internal cross-sectional profile, e.g., as an internal hexagon, internal hexalobe, internal dodecagon, or internal XZN. Drill bits usually have an internal thread of 1 ¼ inch according to the UNC (Unified Thread Standard), i.e., a diameter of 1.25 inches (31.75 mm). The external thread on the drill motor is designed to match the internal thread accordingly. The sleeve is usually made of metal, e.g., steel or aluminium, to ensure high strength and durability. For a rotary drive, the drill motor preferably has an electric motor. A gearbox is typically also provided to reduce and adjust the speed generated by the rotary drive and the torque to a level suitable for the drill bit. Furthermore, a control device can be provided for controlling the speed and / or the torque. A housing can be provided for protecting the internal components. Moreover, a handle can be provided for handling and controlling the device. A fixture for a drill stand can also be provided to attach the drill motor to a drill stand. The drill motor can comprise an integrated cooling system, usually for water cooling, in order to prevent overheating during intensive drilling operations. The tool holder preferably has a projection, with part of the external thread being arranged on the projection. In this manner, the drill bit can be connected more easily to the drill motor via the threaded connection. Preferably, part of the external thread is radially surrounded by the sleeve. This enables automated and tool-free installation of the drill bit on the drill motor. Furthermore, the locking device can comprise a sleeve freewheel to enable or, respectively, facilitate the removal of the drill bit. The locking device can have a sliding element and a coupling element arranged on the shaft, wherein the sleeve can be coupled to the shaft and decoupled from the shaft via the sliding element. Furthermore, the sliding element can be attachable to the gear housing of the drill motor by means of a dowel pin to rigidly fix the sleeve. The internal tool section can have a corner point. Such a corner point can be, for example, the edge of a polygonal internal profile or the edge of a curved tooth profile. An internal hexalobe or an internal XZN are typical curved tooth profiles. The sleeve can have at least one marking element, which is preferably arranged on the outside of the sleeve, the first marking element marking a corner point of the internal profile. The marking element facilitates the assembly and disassembly of drill bits. As mentioned previously, a corner point of the internal profile, which is preferably polygonal, is marked by the first marking element, and, accordingly, a corner point of the polygonal external profile can be inserted in a form-fitting manner into the corner point of the internal profile so that additional locking of the drill bit is avoidable and the assembly process is simplified. In a specific embodiment variant, the marking element comprises a line and / or an arrow. In one embodiment, the first marking element comprises at least a visual and / or physical marking. The marking element can be visually enhanced by visual markings, such as colour markings or symbol markings, so that it becomes visible more readily and faster. Physical markings, such as indentations, elevations, engravings, or imprints, offer the advantage of an abrasion-resistant and durable identification. Furthermore, the tool holder can comprise a drill bit for the tool holder. In this case, the drill bit has at least one marking which indicates the position of the completely unscrewed thread and is preferably concealed by the sleeve in the state of being partially or fully screwed in. The position of the completely unscrewed thread thereby corresponds to the position starting from which the thread is free and the drill bit would fall to the ground without being captured by the operator. The marking thus facilitates the disassembly process and prevents the drill bit from being dropped uncontrollably, whereby damage to the drill bit is reduced. At the position where the external thread abuts the internal thread and screwing into one another has not yet begun, the marking is preferably flush with the end of the sleeve facing the drill bit. The marking can be arranged circumferentially around the polygonal external profile of the connection of the drill bit. In one embodiment, the marking comprises at least a visual and physical marking. In one embodiment, the marking comprises at least a visual or physical marking. The polygonal external profile of the connection of the drill bit can comprise a male square, an external hexagon, or an external dodecagon. The internal tool section is, in the simplest case, an internal hexagon, an internal hexalobe, an internal dodecagon, or an internal XZN. In one aspect, the invention relates to a tool holder for a drill bit,the drill bit having a connection for the tool holder, the connection being formed by a tubular section having an external profile - that is preferably polygonal - on the outside and an internal thread on the inside,the tool holder being connectable to a rotary drive with a rotatable shaft,the tool holder comprising an external thread connectable to the internal thread of the drill bit,characterized in that the tool holder has a sleeve concentrically surrounding the shaft,the sleeve having an internal tool section designed to be form-fitting with the external profile of the drill bit,the tool holder having a releasable locking device by means of which the sleeve can be coupled to the shaft and decoupled from the shaft. Embodiment variants of the tool holder correspond to those of the drill motor. Consequently, the following configurations are provided: The tool holder can have a projection, with part of the external thread being arranged on the projection. Part of the external thread can be radially surrounded by the sleeve. The locking device can have a sliding element and a coupling element arranged on the shaft, wherein the sleeve can be coupled to the shaft and decoupled from the shaft via the sliding element. The sliding element can be connectable in a form-fitting manner to the coupling element, preferably via a gearwheel connection. The sliding element can be suitable for being coupled to the gear housing of a drill motor by means of a dowel pin. The locking device can comprise a sleeve freewheel. The internal tool section can have a corner point. The internal tool section can have an internal hexagon, an internal hexalobe, an internal dodecagon, or an internal XZN. The sleeve can have at least one marking element, which is preferably arranged on the outside of the sleeve, the first marking element marking a corner point of the internal profile. The first marking element can comprise at least a visual and / or physical marking. Said marking can be designed as described above in more detail with regard to the drill motor. DETAILED DESCRIPTION OF THE INVENTION Further details of the invention are explained on the basis of exemplary embodiments using the accompanying figures and the following figure description. Figs. 1a, 1b show a drill bit in two views according to the prior art.Fig. 2 shows a drill motor according to the prior art.Figs. 3a, 3b show a drill motor comprising a tool holder according to the invention in a side view (Fig. 3a) and in an oblique view (Fig. 3b).Figs. 4a, 4b show cross-sections through the drill motor of Figs. 3a and 3b in various operating states.Figs. 5a, 5b show a sleeve of a tool holder with a marking element in a side view (Fig. 5a) and in an oblique view (Fig. 3b).Fig. 6 shows a view of a drill bit according to the invention with a marking. Fig. 1a and Fig. 1b show a drill bit 2 according to the prior art in two oblique views. The drill motor 1 according to the invention, which will be described later, is used for such drill bits 2. The drill bit 2 has a base body 21 corresponding to a circular, straight cylinder. On one side, the base body 21 is closed by an end cap 22, on which a connection 23 for a drill motor 1 is provided. A cutting edge 24 is provided on the opposite open side of the base body 21. As in the example shown, said edge can consist of individual cutting elements 25, which form a cutting trim. The cutting elements 25 generally consist of sintered steel with an admixture of industrial diamond, the cutting trim being welded onto the base body 21. When the drill bit 2 is set in rotation, the cutting elements 25 penetrate the material to be cut (in particular reinforced concrete). The connection 23 is formed by a tubular section 28 that protrudes from the end cap 22. The connection 23 has an external profile 26 on the outside, and an internal thread 27 on the inside. The external profile 26 is designed as an external hexagon. The drill bit 2 is connected to the drill motor 1 via the internal thread 27. Typically, drill bits 2 are equipped with a 1 ¼ inch UNC (Unified Thread Standard) internal thread 27 so that the external thread 11 of the drill motor 1 must be designed appropriately. The drill bit 2 may exhibit channels or openings to remove the drilling dust emerging during drilling or drilling mud that has accumulated. The operation of the drill bit 2 can occur in both dry and wet conditions. A drill motor 1 according to the prior art is shown in Fig. 2. The drill motor 1 has a tool holder 10 comprising an external thread 11. To connect the drill bit 2 to the drill motor 1 via a threaded connection, the internal thread 27 of the drill bit 2 is screwed onto the external thread 11. If the internal thread 27 of the drill bit 2 is equipped with a 1 ¼ inch UNC, the corresponding external thread 11 of the tool holder must be designed appropriately and fittingly. The drill bit 2 is then securely connected to the drill motor 1. During operation, the shaft 31 is set in rotation via a rotary drive 30 installed in the housing 32 of the drill motor 1, the shaft in turn setting the drill bit 2 in rotation via the threaded connection so that drilling can take place. During actual drilling, especially in reinforced concrete, it frequently happens that cutting elements 25 are abruptly decelerated in the reinforcement of the concrete and become wedged with the reinforcement. The rotational movement of the drill bit 2 can lead to an almost inseparable threaded connection, making it difficult to remove the drill motor 1 from the jammed drill bit 2. In the worst case, the tubular section of the connection 23 must be destroyed with an angle cutter to detach the drill motor 1. During the time window until this solution is achieved, it is not possible to work with the drill motor 1. The drill motor 1 according to the invention is shown in a side view and in an oblique view in Figs. 3a and 3b, the internal structure is visible in the sectional views of Figs. 4a and 4b. Fig. 3a shows the drill motor 1 which has a rotary drive 30 integrated into a housing 32. The rotary drive 30 (usually an electric motor) is coupled to a shaft 31 and is designed for setting the shaft 31 in rotation. The rotary drive 30 can be activated and deactivated via an on / off switch. A control element 33 can control the rotation (e.g., rotational speed, torque and / or impact energy for the operation of a hammer drill). The shaft 31 has a tool holder 10 to which the drill bit 2 can be attached. For this purpose, the tool holder 10 has, on the one hand, a projection 14 on which an external thread 11 is provided, which is connectable to the internal thread 27 of the drill bit 2 by means of a threaded connection. On the other hand, the tool holder 10 has a sleeve 12, which is arranged concentrically to the projection 14 and is rotatably mounted on the shaft 31. The sleeve 12 has an internal tool section 13 designed to be form-fitting with the external profile 26 of the drill bit 2. In addition, the internal tool section 13 can be engaged with the external profile 26 of the drill bit 2. Different from the "normal" function of the external profile 26, which serves for loosening the threaded connection or establishing the threaded connection between the connection 23 and the tool holder 10, the power transmission according to the invention does not occur directly from the shaft 31 to the drill bit 2, i.e., no longer via the threaded connection, but rather from the coupling element 35 to the sleeve 12 and via the tool section 13 of the sleeve 12 to the external profile 26 of the drill bit 2. The drill motor 1 has a locking device 29 by means of which the sleeve 12 can be coupled to and decoupled from the shaft 31. The indirect power transmission from the rotary drive 30 of the drill motor 1 via the sleeve 12 to the external profile 26 of the drill bit 2, with the internal tool section 13 and the external profile 26 being in contact, prevents the problem of jamming. The internal structure of the drill motor 1, including the locking device 29, is described in more detail with reference to Figs. 4a and 4b, with Fig. 4a showing the locked state (for the drilling operation) and Fig. 4b showing the detached state of the locking device 29 (for the assembly and disassembly of the drill bit 2). The drill motor 1 has a locking device 29 by means of which two different switching positions are possible so that the sleeve 12 and the shaft 31 can be coupled and decoupled. For this purpose, the locking device 29 comprises a coupling element 35 in the form of a toothed wheel, which is connected to the shaft 31 so that the shaft 31 always rotates with the coupling element 35. Between the coupling element 35 and the shaft 31, a tolerance sleeve 42 is installed which slips through at and above a certain torque. This means that the coupling element 35 can also rotate independently of the shaft 31. With this function, the maximum clamping force between the drill bit 2 and the tool holder 10 is limited. However, as an alternative to a tolerance sleeve 42, a brake element (not shown) could also be provided. In this case, the rotary drive 30 is an electric motor that converts electrical energy into a rotational movement of the coupling element 35, passing it on to the sleeve 12 in the locked state in order to rotate the drill bit 2. Furthermore, a gearbox (not shown) is provided to reduce and adjust the speed generated by the rotary drive 30 and the torque to a level suitable for drilling at the sleeve 12. Control and regulation elements 33 allow the speed and the torque to be controlled and can provide additional safety functions. A handle for handling (not shown) and / or a fixture 46 for a drill stand can be provided on the housing 32 to clamp the drill motor 1 onto a drill stand and to automate the motion. Fig. 4b shows a switching position in which the locking device 29 is detached, i.e., in which the sleeve 12 and the shaft 31 are decoupled. In this state, dowel pins 36 of the locking device 29 engage the gear housing 39 in a form-fitting manner so that the sleeve 12 acts as a fixed bearing. In this switching position, the sliding element 38 is detached from the coupling element 35 and connected only to the sleeve 12. The rotary drive 30 now drives the coupling element 35 and the shaft 31 with the external thread 11 in a clockwise direction via a gearbox. The shaft 31 (and the external thread 11) rotates independently of the sleeve 12 by means of the slide bushings 41. The external thread 11 of the tool holder 10 of the drill motor 1 can now be screwed onto the internal thread 27 of the drill bit 2. When the external thread 11 is fully screwed into the internal thread 27 of the drill bit 2, clamping between the drill motor 1 and the drill bit 2 occurs. The required clamping force is defined by way of the electric motor. Additionally, a tolerance sleeve 42 is installed so that, if the maximum clamping force is exceeded, the shaft 31 can rotate independently of the coupling element 35. In Fig. 4a, the coupled locking device 29 is shown. As soon as the threaded connection between the internal thread 23 of the drill bit 2 and the external thread 11 of the drill motor 1 is established, the locking device 29 is coupled to the coupling element 35 (toothed wheel). For this coupling, the sliding element 38 is, at first, shifted so that the dowel pins 36 do not engage the sliding element 38 anymore. The sliding element 38 is moved towards the coupling element 35 so that the sliding element 38 comes into engagement with the coupling element 35. In this switching position, the shaft 31 and the sleeve 12 are driven simultaneously via the coupling element 35, and subsequently the drill bit 2. The power transmission from the drill motor 1 to the drill bit 2 is ensured exclusively by the form-fitting connection between the external profile 26 of the drill bit 2 and the sleeve 12 of the drill motor 1. Even in the event of the drill bit 2 decelerating abruptly, the clamping of the internal thread 27 of the drill bit 2 and the external thread 11 of the drill motor 1 can no longer become wedged. To detach the drill bit 2 from the drill motor 1, the sliding element 38 is moved back in the opposite direction, starting from the coupled locking device 29 (Fig. 4b), and the dowel pins 36 are reconnected to the gear housing 39. The dowel pins 36 of the locking device 29 form-fittingly engage openings of the gear housing 39. In this state of the locking device 29, the sleeve 12 acts as a fixed bearing. The rotary drive 30 now drives the coupling element 35 and the shaft 31 with the external thread 11 in a counterclockwise direction via the gearbox. The shaft 31 rotates independently of the sleeve 12 by means of the slide bushings 41. Between the coupling element 35 and the shaft 31, a sleeve freewheel 40 is installed which allows the independent rotational movement of the coupling element 35 and of the shaft 31 in a clockwise rotation and transmits the rotational movement of the coupling element 35 to the shaft 31 in a counterclockwise rotation. The external thread 11 of the tool holder 10 of the drill motor 1 can now be unscrewed from the internal thread 27 of the drill bit 2. How to connect the drill bit 2 and the drill motor 1 and how to loosen this connection is described once again in more detail below. Mountingthe drill bit on the drill motor (Fig. 4b):In a method of mounting the drill bit 2 on the drill motor 1, the locking device 29 can first be decoupled. For this purpose, the control element 33 is set to a mounting position, and the locking device 29 is actuated, and the sliding element 38 is connected to the gear housing 39. The sleeve 12 is thus no longer rotatable. The drill bit 2 is pushed onto the tool holder 10 until the external profile 26 of the drill bit 2 engages the sleeve 12 and thus is also no longer rotatable. The rotary drive 30 is also activated so that the shaft 31 rotates. The power transmission via the coupling element 35 to the external thread 27 happens until resistance is encountered and the rotary drive 30 is deactivated. For this purpose, the control can have an operating mode for "drill bit assembly" to set the correct forces. The drill bit 2 is thus mounted on the tool holder 10. To prevent exceeding the specified tightening torque, the rotary drive 30 is electronically throttled with respect to speed and torque in the operating mode "drill bit assembly". A tolerance sleeve 42 can also be installed between the toothed wheel and the drill spindle, which mechanically limits a predeterminable torque. Subsequently, the locking device 29 is coupled. In doing so, the sliding element 38 is coupled to the coupling element 35, and the sleeve 12 is detached from the gear housing 39. The operation of the drill motor can be started via the control element 33, and it can be switched, for example, to the 1st, 2nd, or 3rd gear via the control element 33. The full torque is transmitted to the drill bit 2 entirely via the sleeve 12. The threaded connection only transmits the torque specified by the tolerance sleeve 42. The drill bit 2 can thus be mounted to the tool holder 10 of the drill motor 1 with a predefined torque automatically and without tools. Detaching the drill bit from the drill motor (Fig. 4b):In a method of detaching the drill bit 2 from the drill motor, the locking device 29 is first decoupled. For this purpose, the control element 33 is set to a detaching position, and the locking device 29 will be decoupled, and the sliding element 38 is connected to the gear housing 39. The sleeve 12 is thus no longer rotatable. The rotary drive 30 is activated in the opposite direction ("counterclockwise rotation") so that the shaft 31 rotates. The rotary drive 30 rotates counterclockwise with full torque, but with the speed being electronically throttled, thus disengaging the drill bit 2 from the shaft 31. To ensure that the full torque can be achieved (for drill bit assembly, mechanically throttled by a tolerance sleeve), a so-called sleeve freewheel 40 is installed. Sleeve freewheels 40 are one-way couplings, they transmit torques in only one direction. The drill bit 2 is thus removed from the drill motor 1 automatically and without tools. Locking device in "neutral" positionIn the event of "jamming", it may happen that the sliding element 38 cannot be coupled to the gear housing 39 due to a tooth-on-tooth position between the coupling element and the sliding element 38. In this case, the sliding element 38 can still be decoupled, a neutral position thus also occurs. Since the drill bit 2 is fixed in this case due to jamming, detachment from the shaft 31 is similarly possible without requiring the sleeve 12 to be coupled to the gear housing 39. There is no detenting neutral position when the sliding element 38 is switched to be spring-loaded. As soon as the tooth-on-tooth position changes, the sliding element 38 automatically moves to the preselected operating mode. In Figs. 5a and 5b, the additional aspect of the marking element 44 is explained with reference to the exemplary embodiment of Figs. 3a and 3b. Regarding the general structure of the drill motor 1 and of the tool holder 10, respectively, reference may be made to the figure description of Figs. 3a and 3b (above) with regard to the individual components. Figs. 5a and 5b additionally show that the sleeve 12 of the tool holder 10 is provided with a marking element 44. The marking element 44 is arranged on the outside of the sleeve 12 and marks a corner point 49 of the internal profile. The marking element 44 is visually configured as an arrow using colouring, and, in addition, it is physically identified as an indentation (using milling). The marking element 44 can, of course, be provided at any corner point 49 of the internal profile. The marking element 44 marks a corner point 49 and enables simplified insertion of the drill bit 2 or, respectively, of a hexagonal profile of a drill bit 2. In the exemplary embodiment, the internal tool section marks a corner point 49 in the form of an edge of a curved tooth profile, namely of an internal XZN. When inserting the drill bit 2, the marking element 44 is attached so as to match an edge of the hexagon of the drill bit 2. For facilitating the insertion of the drill bit 2. Fig. 6 shows a drill bit 2 having a marking 45. The drill bit 2 has a connection for the tool holder 10, the connection 23 being formed by a tubular section 23 having an external profile 26 on the outside and an internal thread 27 on the inside. Furthermore, the drill bit has a marking 45 which indicates the position of the completely unscrewed thread and is preferably concealed by the sleeve 12 in the state of being partially or fully screwed in. When loosening the drill bit 2, it is possible to precisely determine in this manner when the connection to the tool holder 10 is loosened. The marking 45 as the horizontal line on the polygonal section is required exclusively on the drill bit 2. It marks the section of the drill bit 2 leaving the thread. In practice, the drill bit 2 is twisted or unscrewed from the tool holder 10 after drilling. Once the thread is completely unscrewed, the drill bit 2 is loosened or free, respectively. The drill bit 2 would fall to the ground without being captured. To prevent the drill bit 2 from falling uncontrollably, the marking 45 is attached, for example, in the form of a groove to indicate the exact starting position for removal. As soon as the marking 45 is visible when unscrewing the drill bit 2, the drill bit 2 is free and can be removed.
Claims
1. A drill motor (1) for a drill bit (2),the drill bit (2) having a connection (23) for the drill motor (1), the connection (23) being formed by a tubular section (23) having an external profile (26) on the outside and an internal thread (27) on the inside,the drill motor (1) having a rotary drive (30) with a rotatable shaft (31),the shaft (31) having a tool holder (10),the tool holder comprising an external thread (11) connectable to the internal thread (27) of the drill bit (2),characterized in that the tool holder (10) has a sleeve (12) concentrically surrounding the shaft (31),the sleeve (12) having an internal tool section (13) designed to be form-fitting with the external profile (26) of the drill bit (2),the drill motor (1) having a releasable locking device (29) by means of which the sleeve (12) can be coupled to the shaft (31) and decoupled from the shaft (31).
2. A drill motor according to claim 1, characterized in that the tool holder (10) has a projection (14), with part of the external thread (11) being arranged on the projection (14).
3. A drill motor according to claim 2, characterized in that part of the external thread (11) is radially surrounded by the sleeve.
4. A drill motor according to any of claims 1 to 3, characterized in that the locking device (29) has a sliding element (38) and a coupling element (35) arranged on the shaft (31), wherein the sleeve (12) can be coupled to the shaft (31) and decoupled from the shaft (31) via the sliding element (38).
5. A drill motor according to claim 4, characterized in that the sliding element (38) is connectable in a form-fitting manner to the coupling element (35), preferably via a gearwheel connection.
6. A drill motor according to any of claims 1 to 5, characterized in that the sliding element (38) can be coupled to the gear housing (39) of the drill motor (1) by means of a dowel pin (36).
7. A drill motor according to any of claims 1 to 6, characterized in that the locking device (29) comprises a sleeve freewheel (40).
8. A drill motor according to any of claims 1 to 8, characterized in that the internal tool section (13) has a corner point.
9. A drill motor according to any of claims 1 to 8, characterized in that the internal tool section (13) has an internal hexagon, an internal hexalobe, an internal dodecagon, or an internal XZN.
10. A drill motor according to claim 8 or claim 9, characterized in that the sleeve (12) has at least one marking element (44), which is preferably arranged on the outside of the sleeve (12), the first marking element (44) marking a corner point (49) of the internal profile.
11. A drill motor according to claim 10, characterized in that the first marking element comprises at least a visual and / or physical marking.
12. A tool holder (10) for a drill bit (2),the drill bit (2) having a connection (23) for the tool holder (10), the connection (23) being formed by a tubular section (23) having an external profile (26) - that is preferably polygonal - on the outside and an internal thread (27) on the inside,the tool holder (10) being connectable to a rotary drive with a rotatable shaft,the tool holder (10) comprising an external thread (11) connectable to the internal thread (27) of the drill bit (2),characterized in that the tool holder (10) has a sleeve (12),the sleeve (12) having an internal tool section (13) designed to be form-fitting with the external profile (26) of the drill bit (2),the tool holder (10) having a releasable locking device (29) by means of which the sleeve (12) can be coupled to the shaft and decoupled from the shaft (31).
13. A drill bit for a drill motor according to any of claims 1 to 11 or a tool holder according to claim 12, wherein the drill bit (1) has a connection (23) formed by a tubular section (23) having an external profile (26) - that is preferably polygonal - on the outside and an internal thread (27) on the inside, characterized in that the drill bit (2) has a marking (45) which indicates the position of the completely unscrewed thread and is preferably concealed by the sleeve (12) in the state of being partially or fully screwed in.
14. A set composed of a drill motor according to any of claims 1 to 11 and a drill bit (2) having a connection (23) for the drill motor (1), wherein the connection (23) is formed by a tubular section (23) having an external profile (26) on the outside and an internal thread (27) on the inside.
15. A set according to claim 14, characterized in that the drill bit (2) has a marking (45) which indicates the position of the completely unscrewed thread and is preferably concealed by the sleeve (12) in the state of being partially or fully screwed in.