Method for removing a tool and system for carrying out the method

Abstract

The invention relates to a method for releasing a self-tightening insert tool (28) in a working direction (O) of a tool spindle (30) of a hand-held power tool (12), comprising at least the following steps (78, 82, 84): securing the insert tool (28) against rotation with a holding tool (38) when the tool spindle (30) is stationary, starting the tool spindle (30) in the opposite direction of working rotation (O), and stopping the tool spindle (30) after a defined number (N) of revolutions. The invention further relates to a system comprising a hand-held power tool (12), in particular a diamond core drill (10), an insert tool (38), in particular a core drill (70), and a holding tool (38), in particular a wrench (40), for carrying out the method.

Description

[0001] The invention relates to a method for releasing a self-tightening insert tool in a working direction of rotation of a tool spindle of a hand-held power tool according to the preamble of independent claim 1. Furthermore, the invention relates to a system comprising a machine tool, in particular a diamond drilling machine, an insert tool, in particular a drill bit, and a holding tool, in particular a wrench, for carrying out the method. State of the art

[0002] Some handheld power tools, such as diamond core drills, have a spindle that rotates only clockwise, as the corresponding tools, especially drill bits, are designed for this direction of rotation. Driving the spindle in the opposite direction is generally not possible with these types of power tools. The tools are connected to the spindle via an internal thread, which then tightens itself during operation in the working direction until it reaches a stop on the spindle.Two open-end wrenches are often required to initially loosen the tool insert. One wrench grips the tool spindle, and the other grips the tool insert in such a way that an operator can turn the wrench gripping the insert in the opposite direction of rotation of the tool spindle, which is fixed against rotation. The tool insert must then be manually unscrewed from the thread of the tool spindle.

[0003] EP 2 977 132 A1 discloses a device for receiving and securing a tool, in particular a drill bit, on a hand-held power tool, for example a core drilling machine, comprising a tool spindle for transmitting a torque generated in the power tool to the tool and a union nut positioned around the tool spindle for releasably connecting the tool spindle to a terminal end of the tool. The device is designed such that the tool can be mounted and dismounted on the power tool by hand without the use of any other tool.

[0004] The object of the invention is to further simplify and accelerate the loosening of a self-tightening insert tool in a working direction of rotation of a tool spindle, a process known from the prior art. Advantages of the invention

[0005] To solve the problem, the method according to the invention comprises at least the following steps: • Securing the tooling unit against rotation when the tool spindle is at rest using an additional holding tool, • Starting the tool spindle against the direction of rotation and • Stopping the tool spindle after a defined number of revolutions.

[0006] A particular advantage of this is that the process of manually removing the insert from the tool spindle after initial loosening is significantly accelerated and simplified by the machine assistance of the handheld power tool. Furthermore, only a single holding tool is required for the loosening process, which facilitates handling and makes the overall process safer, as the operator can hold the power tool with one hand and the insert with the other after the initial loosening. This is especially advantageous with a diamond core drill using a relatively heavy drill bit.

[0007] A further development of the invention provides that, prior to starting the tool spindle in the opposite direction of rotation, a start authorization is required in a prior step. For this purpose, the machine tool has a push button or switch by means of which the starting of the tool spindle in the opposite direction of rotation can be authorized. Alternatively or additionally, the handheld machine tool can have a communication interface via which the starting of the tool spindle in the opposite direction of rotation can be authorized by means of an external data processing device. The communication interfaces of the handheld machine tool and the external data processing device can transmit the authorization signal wirelessly, for example via WLAN, BT, Zigbee, NFC, or the like. Wired communication interfaces, e.g., via USB-C or the like, are also conceivable.An external data processing device is defined as a device physically separate from the hand-held power tool. Examples of external data processing devices include smartphones, smartwatches, or tablets with a suitable app installed, or personal computers with appropriate software installed. The enable signal allows for easy switching between rotation directions, while the speed and / or torque of the tool spindle can be controlled via a main button on the hand-held power tool.

[0008] To increase safety, the release should preferably only occur if the tool spindle has come to a complete stop before starting rotation in the opposite direction to the working direction. Furthermore, it can be provided that after a defined period of time following activation of the button or switch, receipt of the release signal, and / or after reactivation of the main button, the working direction is automatically reset. Preferably, the currently set direction of rotation is displayed to the operator on the handheld power tool via a display element, for example, in the form of two LEDs, an LCD, or the like. Acoustic or haptic signaling, particularly after a release to change the direction of rotation, is also conceivable.

[0009] Furthermore, it is provided that the number of revolutions until the tool spindle stops is calculated by dividing the length of a thread provided on the tool spindle for the insert tool by the sum of the thread pitch and a constant. Preferably, this constant has a value between 1 and 5, preferably 3. This significantly reduces the effort required for manually turning the insert tool and also prevents the insert tool from accidentally falling off.

[0010] The invention also relates to a diamond drilling machine with a tool spindle for holding a drill bit and a main button for changing the speed of the tool spindle, wherein the drill bit tightens itself in one working direction of rotation of the tool spindle by means of a thread. According to the invention, the diamond drilling machine is provided with a button or switch or a communication interface for releasing the drill bit, via which rotation of the tool spindle against the working direction of rotation can be enabled, wherein the speed of the tool spindle can be changed after release via the main button. Examples of implementation Drawing

[0011] The invention is described below with reference to the Fig. Figures 1 to 3 are explained by way of example, whereby identical reference symbols in the figures indicate identical components with the same function.

[0012] They show: Fig. 1: A hand-held power tool designed as a diamond drilling machine for carrying out the method according to the invention in a perspective view, Fig. 2: a drill bit designed as a core drill and a holding tool designed as a wrench as parts of the system according to the invention in a perspective view and Fig. 3: a flowchart of the process according to the invention. Description of the exemplary implementations

[0013] Fig. Figure 1 shows a perspective view of a battery-powered hand tool 12 designed as a diamond drilling machine 10, which is supplied with energy via two interchangeable battery packs 14. The diamond drilling machine 10 has a housing 16 which, together with a main handle 18 arranged at the rear end, forms a D-shaped recess 20. During the machining process, the main handle 18, together with an auxiliary handle 24 arranged at the front end of a gearbox housing 22, serves to guide the diamond drilling machine 10 in a working direction W. To reduce the vibrations acting on the operator during the machining process, the main handle 18 and the auxiliary handle 24 can be connected to the housing 16 and the gearbox housing 22, respectively, by means of vibration damping or decoupling. A person skilled in the art will be familiar with the corresponding measures for vibration damping or decoupling, so they are not the subject of the invention.

[0014] The housing 16 and the main handle 18 are integrally joined and formed from two housing halves. "Integrated" here means that the joined parts are manufactured from the same material, preferably in a single manufacturing step, for example by means of plastic injection molding. The gearbox housing 22 is preferably made of metal and is screwed to the housing 16. A gearbox (not shown in detail) is arranged in the gearbox housing 22, by means of which a tool holder 26 is provided for the alternating mounting of a tool. Fig. The insert tool 28, as shown in Figure 2, is driven by a tool spindle 30 about a rotational axis R in a working direction O. The tool holder 26 has an external thread 32 with a length L and a pitch S, onto which the insert tool 28 can be screwed with a corresponding internal thread such that, during operation of the diamond drilling machine 10, it tightens itself against a stop due to the rotation of the tool spindle 30 in the working direction O and the frictional resistance acting against the insert tool 28. The stop and the internal thread of the insert tool 28 are shown in Fig. 2 is only indicated and is located inside a rear threaded boss 34 of the insert tool 28. The threaded boss 34 has a hexagonal profile 36 around its outer circumference, which can be gripped by a holding tool 40, designed as an open-end wrench 38, for tightening or loosening the insert tool 28 in a form-fit and force-fit manner. According to the prior art, a second open-end wrench 38 (not shown) is placed on a flange 42, which is rotationally fixed to the tool spindle 30 and has two diametrically opposed flats on its outer circumference, in a form-fit and force-fit manner to rotate the two open-end wrenches 38 in opposite directions. Alternatively, instead of the two flats, the flange 42 can also have a hexagonal profile corresponding to the hexagonal profile 36 of the insert tool 28.

[0015] The operator of the diamond drilling machine 10 can select two different gear stages of the gearbox via a gear selector switch 44 attached to the gearbox housing 22. The gearbox is driven by an electric motor 46 located in the housing 16, which is supplied with energy by an electronic unit consisting of power electronics and a control unit. The electronic unit is also located in the housing 16 and serves to regulate or control the electric motor 46 such that, depending on the travel of a main push button 48 and the setting of the gear selector switch 42, a desired speed and / or a desired torque of the electric motor 46 and the tool 28 driven by it can be preset.The main button 48 is located in the main handle 18 of the diamond drilling machine 10, which itself is essentially formed from two half-shells shaped as grip shells, each integrally connected to the half-shells of the housing 16. The two grip shells are at least partially coated with a soft component to provide improved and more comfortable grip for the operator. The soft component is preferably a thermoplastic elastomer (TPE). The further the main button 48 is pressed into the main handle 18, the higher the speed and / or torque of the electric motor 46.To control the speed and / or torque of the electric motor 46, which is designed as an EC motor, the control unit controls the power electronics, designed as a power bridge, by pulse width modulation (PWM) such that the power bridge applies trapezoidal or nearly sinusoidal commutation to the individual phases of the EC motor in a known manner. When the main button 48 is released, it is automatically released by a spring force, and the electric motor 46, along with the tool spindle 30 driven by it via the gearbox, comes to a standstill.

[0016] The two interchangeable battery packs 14 can be detachably connected to the diamond drilling machine 10 via appropriately designed electromechanical interfaces 50, 52 on the battery packs 14 or on a section 54 of the housing 16 adjacent to the electric motor 46 within the D-shaped recess 20. The electromechanical interfaces 52 are aligned with each other on section 54 of the housing 16 such that they run parallel to each other for the interchangeable battery packs 14. The operator can then insert the interchangeable battery packs 14 with their electromechanical interfaces 50 into the corresponding electromechanical interfaces 52 of the diamond drilling machine 10 transversely, in particular at right angles, to the working direction W and lock them into place. During operation of the diamond drilling machine 10, the interchangeable battery packs 14 are discharged via the electromechanical interfaces 50, 52.The charge status of each interchangeable battery pack 14 can be read via a charge status indicator 56 of the interchangeable battery pack 14 designed as an LED segment display.

[0017] The voltage class of a battery pack 14 is determined by the connection (parallel or series) of the individual energy storage cells integrated into the battery pack 14 (not shown) and is generally an integer multiple (>= 1) of the voltage of the individual energy storage cells. An energy storage cell is typically designed as a galvanic cell with a structure in which one cell pole is located at one end and another cell pole at the opposite end. In particular, the energy storage cell has a positive cell pole at one end and a negative cell pole at the opposite end. Preferably, the energy storage cells are designed as lithium-based cylindrical cells, e.g., Li-ion, Li-polymer, Li-metal, or the like, with the cell poles arranged at flat ends of the cylindrical shape. However, Ni-Cd, Ni-MH cells, or other suitable cell types are also applicable.Common lithium-ion energy storage cells typically have a cell voltage of 3.6 V. Different cell voltages are possible for pouch cells and / or cells with a different electrochemical composition. While the invention is not dependent on the type and design of the energy storage cells used, but can be applied to any interchangeable battery packs 14 that utilize prismatic cells, pouch cells, or the like instead of cylindrical cells, interchangeable battery packs 14 with a voltage class of 18 V are shown as an example, so that the diamond drilling machine 10 is operated with a supply voltage of 36 V when two interchangeable battery packs 14 are connected in series.

[0018] The diamond drilling machine 10 can additionally be controlled via an external data processing device 58. For the purposes of this invention, an external data processing device 58 is understood to be a device spatially separate from the diamond drilling machine 10. Fig. 1. The external data processing device 58 is, for example, configured as a smartphone 60, which communicates with a data interface 64 of the diamond drilling machine 10 via a data interface 62. The data interfaces 62 and 64 can be configured, for example, as mutually compatible wireless Bluetooth, WLAN, or NFC interfaces, or as wired USB, Lightning, RS232 interfaces, or the like, for unidirectional or bidirectional data exchange. The control or setting of operating parameters and / or the display of operating data of the diamond drilling machine 10 is carried out via a human machine interface (HMI) 66 of the external data processing device 58, preferably configured as a display, in particular a touchscreen. A special app or operating program can be provided for this purpose. Alternatively or additionally, the settings can also be made or displayed directly via an HMI 68 of the diamond drilling machine 10.The HMI 68 can also be configured as a display or an LED indicator with a keypad, as an acoustic signal generator, such as a speaker, and / or as a haptic signal generator, such as a vibration motor. Instead of a smartphone 60, the external data processing device 58 can alternatively be configured as a smartwatch or tablet with a correspondingly installed app, or as a local personal computer or a remote server with a correspondingly installed program.

[0019] Fig. Figure 2 shows the previously mentioned tool 28 in the form of a core drill 70. In the illustrated embodiment, the core drill 70 has a length of approximately 500 mm and a diameter of approximately 130 mm. It is designed as a hollow cylinder open at one end, which has a threaded boss 34 with a circumferential hexagonal profile 36 at its closed end and a plurality of diamond-coated cutting segments 72 at its open end for producing core holes in concrete. For this purpose, the core drill 70, which is screwed onto the tool spindle 30 of the diamond drilling machine 10, is driven in the working direction O – generally with clockwise rotation, as indicated by the arrowhead – to achieve a feed in the working direction W. The thread 32 of the tool holder 26 and the internal thread of the threaded dome 34 are designed such that the drill bit 70 tightens itself automatically during operation in the working direction O as a result of the opposing frictional resistance.At the end of the work process, the operator pulls the drill bit 56 out of the core hole along with the drilled core, in order to finally remove and dispose of the core from the drill bit 56.

[0020] In order to significantly accelerate and simplify the process of loosening or manually unscrewing the drill bit 70 screwed onto the tool spindle 30 after initial loosening by mechanical assistance of the diamond drilling machine 10, the following inventive method is described in accordance with the invention described in Fig. The process is described in the flowchart shown in Figure 3. In a first step 74, the procedure begins with the initial release of the drill bit 70 in the manner described above. In the subsequent step 76, the drill bit 70 is secured against rotation with the open-end wrench 38 while the tool spindle 30 is stationary. In step 78, the tool spindle 30 is enabled to start in the opposite direction of rotation O. For this purpose, the diamond drilling machine has a push button 80 at the upper end of the main handle 18, which allows the tool spindle 30 to be started in the opposite direction of rotation O. If the operator has pressed the push button 80 in step 78, they can start the tool spindle 30 in the opposite direction of rotation O in step 82 using the main push button 48. Additionally, the push button 80 can be used to trigger a locking device for the main push button 48 in any desired position.By pressing button 80 again or by pressing the main button 48, the main button 48 can be released again, for example to allow it to disengage automatically due to its spring action and to stop the electric motor 46.

[0021] Alternatively or additionally, step 78 can be provided for to release the machine via the external data processing device 58, whereby a corresponding release signal F can be transmitted from the external data processing device 58 to the diamond drilling machine 10 via the communication interface 62, 64. The release signal F allows switching between the directions of rotation of the tool spindle 30, whereby the speed and / or torque of the tool spindle 30 can be controlled via the main button 48 in step 82. To increase safety, it can also be provided that release in step 78 is only possible if the tool spindle 30 has come to a standstill after a machining operation. Detection of the standstill of the tool spindle 30 can be achieved via a speed sensor (not shown), which, for example, serves to detect the rotor position of the electric motor 46. Sensing via the motor current is also conceivable.

[0022] Alternatively or additionally, it can be provided that after a defined time interval T has elapsed following the activation of button 80 or the receipt of the release signal F and / or after a further activation of the main button 48, the working direction of rotation O is automatically reset, so that the procedure ends in step 84. The currently set direction of rotation is displayed to the operator via the HMI 68. Acoustic or haptic signaling, particularly after the release to change the direction of rotation, is also conceivable.

[0023] If the time interval T has not yet elapsed or if no time interval T is specified, the tool spindle 30 is stopped in step 84 after a defined number N of revolutions. The number N of revolutions until the tool spindle 30 stops is calculated by dividing the length L of the thread 32 of the tool holder 26 by the sum of the pitch S of the thread 32 and a constant K. N=L / (S+K), where the constant K has a value between 1 and 5, preferably 3, and the pitch S is considered analogous to the length L as a length measurement, for example in millimeters. This significantly reduces the effort required for manually turning the drill bit 70 and prevents accidental detachment. Furthermore, only a single open-end wrench 40 is required for the loosening process, which simplifies handling and makes the process safer overall, as the operator can hold the diamond drill 10 with one hand and the drill bit 70 with the other after the initial loosening.

[0024] Finally, it should be noted that the illustrated embodiment does not refer to the Fig.Sections 1 to 3 are still limited to the aforementioned values ​​for the dimensions of the drill bit 70 and the described configuration of the system comprising the diamond drill 10, the drill bit 70, and the open-end wrench 40 for carrying out the method according to the invention. Furthermore, the pushbuttons 48 and 80 mentioned in the description can also be replaced by switches with the same operating principle. A pushbutton differs from a switch, in particular, in that the switch has at least two stationary switching states (bistable), while the pushbutton has only one stationary state (monostable). QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2 977 132 A1

[0003]

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