Method for operating handheld power tools

Abstract

This invention relates to a method for operating a handheld power tool, wherein the handheld power tool includes an electric motor, and to a method comprising the steps of: A) performing a tightening of a connecting device in a base; S2 providing at least one signal of an operating parameter (200) of the electric motor (180) during the tightening; C) evaluating the recorded signal of the operating parameter (200) of the electric motor (180); D) determining whether the tightening was performed as intended, wherein the determination is based at least in part on the evaluation of the received signal of the operating parameter (200) of the electric motor (180). The invention also relates to a handheld power tool.

Description

Technical Field

[0001] This invention relates to a method for operating a handheld machine tool and a handheld machine tool configured to perform the method. In particular, this invention relates to a method for quality assurance during tightening operations performed with a handheld machine tool. Background Technology

[0002] Rotary impact screwdrivers for tightening bolt elements such as nuts and screws are known from the prior art (see, for example, EP 3 202 537 A1). This type of rotary impact screwdriver includes, for example, a configuration in which an impact force in the rotational direction is transmitted to the bolt element via the rotational impact force of a hammer. A rotary impact screwdriver with this configuration includes a motor, a hammer to be driven by the motor, an anvil struck by the hammer, and a tool. The rotary impact screwdriver also includes a position sensor for detecting the position of the motor and a control device coupled to the position sensor. The control device detects the impact of the impact mechanism, calculates the drive angle of the anvil caused by the impact based on the output of the position sensor, and controls a brushless DC motor based on the drive angle.

[0003] An electrically driven tool with an impact mechanism is also known from US 9,744,658, in which the hammer is driven by a motor. Furthermore, rotary impact screwdrivers include methods for recording and reproducing motor parameters.

[0004] Rotary screwdrivers are used in a wide range of applications, especially for direct tightening in dense concrete or natural stone, using special concrete screws. In these bolting applications, a tenon (dübel) is not required. This saves time during assembly and provides the advantage of a connection without expansion pressure. Upon screwing in, the thread is tangential to a precisely matched mating thread in the base.

[0005] Problems arise in this type of direct tightening when the user continues to rotate the screw after it has been tightened during impact operation. This can damage the grooved or notched threads in the material or the screw itself. If the user fails to notice this defect and leaves the screw in this tightened state, it may lead to tightening failure at a later point in time.

[0006] When using a rotary impact screwdriver, a high degree of focus on the work progress is required from the user to react appropriately to determined changes in machine characteristics (e.g., the start or stop of the impact mechanism), such as stopping the motor and / or changing the speed via a manual switch. Because users often cannot react quickly or appropriately to the work progress, over-tightening of the screw may occur during the screwing-in process, and if the screw is turned out at too high a speed, it may fall out during loosening.

[0007] Therefore, what is generally desirable is to automate the operation to a greater extent and help customers more easily achieve fully closed work progress and ensure reliable replication of high-quality screw-in and screw-out processes.

[0008] Furthermore, users should be supported by machine-triggered responses or routines (so-called smart tool functions) that are commensurate with the progress of work. Examples of such machine-triggered responses or routines include, for example, the shutdown of a motor, a change in motor speed, or the triggering of a notification to the user.

[0009] Such intelligent tool functionality is particularly enabled by recognizing the current operating state. In the prior art, the recognition of this operating state is performed independently of determining the progress of work or the state of the application, for example, by monitoring the operating parameters of the motor (e.g., speed and motor current). Here, it is checked whether the operating parameters have reached defined limit values ​​and / or thresholds. Corresponding evaluation methods operate using absolute thresholds and / or signal gradients.

[0010] The disadvantage here is that fixed limits and / or thresholds can only be perfectly set for a single application scenario. Once the application scenario changes, the corresponding current or speed values, or their time-varying curves, will also change, and the impact identification based on the set limits and / or thresholds, or their time-varying curves, will no longer be effective.

[0011] Therefore, the following may occur: for example, in some individual applications, automatic shutdown based on the recognition of impact operation is reliably shut off in different speed ranges when using self-tapping screws; however, in other applications, shutdown does not occur when using self-tapping screws.

[0012] In other methods for determining the operating mode of a rotary impact screwdriver, additional sensors (e.g., accelerometers) are used to infer the current operating mode from the vibration state of the tool.

[0013] The disadvantages of these methods are the additional cost of sensors and the loss of robustness in handheld machine tools, as the number of components and electrical connections installed increases compared to handheld machine tools without these sensors.

[0014] Furthermore, simple information about whether the impact mechanism is working is often insufficient to make an accurate statement about the progress of the work. For example, when screwing in a wood screw, the impact mechanism may have already started working very early, before the screw is fully driven into the material, but the required torque already exceeds the so-called release torque of the impact mechanism. That is, a response based solely on the operating state of the rotating impact mechanism (impact operation and non-impact operation) is insufficient for the proper automatic system functions of the tool (e.g., shutdown). Summary of the Invention

[0015] In principle, there is also the problem of maximizing the automation of operation in other hand-held machine tools such as impact drills, so the present invention is not limited to rotary impact screwdrivers.

[0016] Another aspect of the invention includes automated information exchange within a framework where devices are networked via an Internet of Things (IoT) solution. In this case, power tools are able to record data and provide it for processing.

[0017] The object of this invention is to provide an improved method for operating a handheld machine tool, which at least partially eliminates the aforementioned disadvantages, or provides an alternative to the prior art. Another object is to provide a corresponding handheld machine tool.

[0018] These tasks are addressed by means of the corresponding subject matter of the independent claims. Advantageous configurations of the invention are the subject matter of the dependent claims.

[0019] According to the present invention, a method for operating a handheld machine tool with an electric motor is provided, the method comprising the following steps:

[0020] S1 tightens the connecting device in the base;

[0021] S2 provides at least one signal of the motor's operating parameters during tightening;

[0022] S3 is the recorded signal used to evaluate the operating parameters of the motor;

[0023] S4 determines whether tightening has been performed as specified, wherein the determination is based at least in part on an evaluation of the recorded signals of the motor.

[0024] Therefore, according to the method of the present invention, intelligent tool functions are utilized within the framework of continuously advancing digitalization in planning and implementation (the key term here is "networked construction site 4.0") to contribute to tight documentation and quality assurance.

[0025] Here, the signals that provide operating parameters also include possible signal processing of the measured signals, such as in the sense of classifying or clustering the measured signals.

[0026] The method according to the invention effectively supports users of handheld machine tools in achieving reproducible, high-quality application results and in automatically identifying improperly applied tightening. This allows for the repeated identification and elimination of unavoidable user errors.

[0027] To document whether tightening, such as direct concrete tightening, is performed properly, a characteristic documentation method for tightening using a rotary impact screwdriver is disclosed according to the present invention. This ensures that the professional implementation of tightening is documented at all times.

[0028] This invention can be applied to any type of tightening when using tenons and / or self-tapping screws. Particularly advantageously, this invention can be used to identify improperly tightened self-tapping screws, especially in cases of direct concrete tightening.

[0029] That is, the present invention can provide assistance to users, enabling them to maintain the same quality of work with minimal cost.

[0030] In one implementation, the operating parameter is the motor speed or an operating parameter associated with the speed.

[0031] The tightening characteristics can be described by describing the motor speed of a rotary impact screwdriver over time. The deeper the screw penetrates into the material, the higher the impact frequency. The motor speed then fluctuates with this impact frequency. The higher the impact frequency, the lower the motor speed. What was initially considered a "soft tightening" situation is increasingly becoming a "hard tightening" situation.

[0032] If the impact frequency continues to increase during tightening (primarily at the bolt seat), and a decrease in impact frequency is recorded during tightening (that is, the motor speed increases as speed fluctuations decrease), this is an indication of improper tightening.

[0033] In one embodiment, the connecting device is a self-tapping screw, preferably a self-tapping concrete screw.

[0034] In one embodiment, the base is at least partially made of concrete, preferably reinforced concrete.

[0035] In one embodiment, the method according to the invention includes the method steps of visualizing the evaluation of the recorded signal of the electric motor on the human-machine interface (HMI) of a handheld machine tool, particularly the visualization of incorrect tightening.

[0036] In one embodiment, the method according to the invention includes the step of sending a message regarding an evaluation of a recorded signal of the electric motor (particularly regarding improperly handled tightening) to an external device. Sending the message can include sending a push message to a handheld device, particularly a smartphone.

[0037] In one embodiment, the method according to the invention includes the method steps of recording an evaluation of the recorded signals of the motor, particularly recording improperly handled tightening based on a document, preferably in a 3D assembly drawing. Here, the recording method steps can include detecting and storing the tightening position, especially when using a position sensor from a handheld machine tool.

[0038] In one implementation, the evaluation of the recorded signals from the motor can include the following steps:

[0039] S31 provides at least one typical state model signal form, wherein the typical state model signal form can correspond to the working progress of the handheld machine tool;

[0040] S32 compares the signals of the operating parameters with the typical model signal patterns of the state, and obtains a consistency assessment from the comparison;

[0041] S33 identifies progress of work at least in part based on the conformity assessment obtained in method step S32.

[0042] In some embodiments of the present invention, when determining whether tightening has been performed as required, the identification of work progress is taken into account.

[0043] If, for example, it is found that the progress of the work at the end of the tightening process corresponds to the state in which the screw head, which is already lying flat on the fastening carrier, is further rotated, this can serve as an indication that the thread with a notch or groove at the bottom is at least partially damaged and the tightening is not performed as specified.

[0044] In such a case, the characteristic of work progress that is not tightened according to regulations is that while the impact frequency continues to increase during the tightening process, a decrease in the impact frequency is recorded, that is, the motor speed increases while the speed amplitude decreases.

[0045] The scheme for identifying work progress by measuring operating parameters (such as the speed of an electric motor) within the tool has proven particularly advantageous because it allows for work progress to be measured with exceptional reliability and largely independent of the overall operating state of the tool or its application.

[0046] Here, sensor units (e.g., acceleration sensor units) for measuring parameters inside the detection tool are essentially omitted, so that essentially only the method according to the invention is used to detect the progress of the work.

[0047] In particular, in method step S31, the model signal form can be variably, especially defined by the user. Here, the model signal form corresponds to the work progress to be identified, so that the user can pre-define the work progress to be identified.

[0048] Advantageously, the model signal configuration is predefined, especially as specified at the factory level. It is conceivable, in principle, that the model signal configuration is stored or preserved internally within the device, or alternatively and / or additionally provided to the handheld machine tool, particularly from external data devices.

[0049] Those skilled in the art will recognize that the characteristics of model signal patterns include signal patterns representing the continuous progression of a working process. In one embodiment, the model signal pattern relates to a state-typical model signal pattern that is state-typical for a given working progress of a handheld machine tool. Examples of such working progress include the flat placement of a screw head on a fastening base, the free rotation of a loose screw, the insertion or removal of a rotary impact mechanism of the handheld machine tool, the achievement of a defined insertion depth of a connecting device to be screwed into by the handheld machine tool, and / or the impact of the rotary impact mechanism when the impacted element or tool receiver no longer rotates.

[0050] In one embodiment of the invention, in method step S32, the determination of the conformity assessment includes comparing the conformity between the signal of the operating parameter and the model signal morphology with at least one threshold of conformity.

[0051] In one embodiment of the invention, in method step S2, the signal of the operating parameter is recorded as a time-varying curve of the measured value of the operating parameter, or as a measured value of the operating parameter on a parameter of the motor associated with the time-varying curve.

[0052] In an embodiment of the present invention, in method step S2, the signal of the operating parameter is recorded as a time variation curve of the measured value of the operating parameter, and in method step S2a, the time variation curve of the measured value of the operating parameter is transformed into a variation curve of the measured value of the operating parameter on the parameter of the motor associated with the time variation curve.

[0053] It is essentially possible to consider different operating parameters as operating parameters recorded by suitable measurement sensors. Particularly advantageously, according to the invention, no additional sensors are required for this purpose, since various sensors (preferably Hall sensors) for speed monitoring are already incorporated into the motor.

[0054] Advantageously, the operating parameter is the motor speed or an operating parameter related to the speed. This is caused by the rigid transmission ratio between the motor and the impact mechanism, resulting in, for example, a direct dependence of the motor speed on the impact frequency. Another conceivable operating parameter related to the speed is the motor current. Motor voltage, the motor's Hall effect signal, battery current, or battery voltage can also be conceived as operating parameters of the motor. Furthermore, the acceleration of the motor, the acceleration of the tool receiver, or the acoustic signal of the impact mechanism of a handheld machine tool can also be conceived as operating parameters.

[0055] In some embodiments, in method step S2, the signal of the operating parameter is recorded as a time-varying curve of the measured value of the operating parameter, or as a measured value of the operating parameter associated with the time-varying curve of the motor, such as acceleration, jolt, especially higher-order jolt, power, energy, rotation angle of the motor, rotation angle of the tool receiver, or frequency.

[0056] The implementation method mentioned last can ensure that the signal to be checked is generated at a constant cycle, regardless of the motor speed.

[0057] In one embodiment of the invention, in method step S32, the signal of the operating parameter is compared by means of a comparison method as follows: whether it meets at least one pre-given threshold of conformity.

[0058] Preferably, the comparison method includes at least one frequency-based comparison method and / or a comparison method for making comparisons.

[0059] Here, at least in part, frequency-based comparison methods, especially bandpass filtering and / or frequency analysis, can be used to make a judgment about whether the progress of the work to be identified can be found in the signal of the operating parameters.

[0060] In one implementation, the frequency-based comparison method includes at least bandpass filtering and / or frequency analysis, wherein a pre-defined threshold is at least 90%, particularly 95%, and especially 98% of a pre-defined limit value.

[0061] In bandpass filtering, for example, the recorded signal of the running parameters is filtered by a bandpass filter whose channel region corresponds to the shape of the model signal. When there is a decisive, identifiable progress in the work, a corresponding amplitude can be expected in the resulting signal. Therefore, a pre-defined threshold for the bandpass filter can be at least 90%, particularly 95%, and entirely, particularly 98% of the corresponding amplitude in the work progress to be identified. Here, the pre-defined limit value can be the corresponding amplitude in the resulting signal of the desired work progress to be identified.

[0062] Using known frequency-based contrast methods, frequency analysis allows searching for a previously defined model signal pattern, such as the spectrum of the work progress to be identified, within the recorded signal of the operating parameters. The corresponding amplitude of the work progress to be identified can be anticipated within the recorded signal of the operating parameters. A pre-defined threshold for frequency analysis can be at least 90%, particularly 95%, and almost certainly 98% of the corresponding amplitude of the work progress to be identified. Here, the pre-defined limit can be the corresponding amplitude in the recorded signal of the ideal work progress to be identified. Appropriate segmentation of the recorded signal of the operating parameters is required in this process.

[0063] In one implementation, the comparison method includes at least one parameter estimation and / or cross-correlation, wherein a pre-given threshold is at least 40% of the consistency between the signal of the running parameter and the morphology of the model signal.

[0064] A comparison method can be used to compare the measured signal of the operating parameter with the model signal pattern. The measured signal of the operating parameter is obtained such that it has a finite signal length that is essentially the same as the signal length of the model signal pattern. Here, the comparison between the model signal pattern and the measured signal of the operating parameter can be a finite-length signal, particularly a discrete or continuous signal. Based on the degree of similarity or deviation of the comparison, a result regarding the existence of the work progress to be identified can be output. When the measured signal of the operating parameter matches the model signal pattern by at least 40%, the work progress to be identified exists. Furthermore, it is conceivable that the comparison method can output the degree of comparison between the measured signal of the operating parameter and the model signal pattern as a comparison result. Here, a comparison of at least 60% can be used as a standard for the existence of the work progress to be identified. Based on this, the lower limit of similarity is at 40%, and the upper limit of similarity is at 90%. Correspondingly, the upper limit of deviation is at 60%, and the lower limit of deviation is at 10%.

[0065] During parameter estimation, a simple comparison can be made between the previously defined model signal pattern and the signal of the operating parameters. To this end, the estimated parameters of the model signal pattern can be identified so that the model signal pattern is adapted to the measured signal of the operating parameters. By comparing the estimated parameters with the previously defined model signal pattern and the limiting values, the results of identifying the progress of the work can be determined. The results of this comparison can then be further evaluated: whether a pre-given threshold has been reached. This evaluation can either determine the quality of the estimated parameters or the consistency between the defined model signal pattern and the detected signal of the operating parameters.

[0066] In another embodiment, method step S32 includes step S32a, which determines the quality of the identification of model signal morphology in the signals of operating parameters, wherein, in method step S33, the identification of work progress is performed at least in part based on the quality determination. The fit quality of the estimated parameters can be obtained as a metric for the quality determination.

[0067] In method step S33, a judgment can be made, at least in part, by means of quality determination, especially quality measurement, to determine whether the progress of the work to be identified is identified in the signal of the operating parameters.

[0068] Additionally or alternatively, method step S32a may include comparing the identified model signal pattern with the signal of the operating parameters to determine the quality. The comparison between the estimated parameters of the model signal pattern and the measured signal of the operating parameters may be, for example, 70%, particularly 60%, or entirely, particularly 50%. In method step S33, at least in part, a determination is made based on the comparison to determine whether the work progress to be identified exists. When the conformity between the measured signal of the operating parameters and the model signal pattern is at least 40% of a pre-defined threshold, it can be determined that the work progress to be identified exists.

[0069] During cross-correlation, a comparison can be made between the previously defined model signal pattern and the measured signal of the operating parameters. Cross-correlation allows the previously defined model signal pattern to be associated with the measured signal of the operating parameters. When the model signal pattern and the measured signal of the operating parameters are associated, a measure of the consistency between the two signals can be obtained. The consistency measure can be, for example, 40%, particularly 50%, or completely particularly 60%.

[0070] In method step S33 of the method according to the invention, the progress of the work can be identified at least in part based on the cross-correlation between the model signal morphology and the measured signal of the operating parameters. Here, identification can be made at least in part based on the consistency of at least 40% of the pre-given threshold between the measured signal of the operating parameters and the model signal morphology.

[0071] In one implementation, the compliance threshold can be predefined by the user of the handheld machine tool and / or predefined at the factory level.

[0072] In one embodiment, the method according to the present invention includes the following method steps:

[0073] S5 implements the first routine of the handheld machine tool based at least in part on the progress of work identified in method step S33.

[0074] Therefore, according to the present invention, the handheld machine tool can respond to different application scenarios. A first routine can include a change in the rotational speed of the motor, particularly a decrease and / or an increase. The first routine can exemplary be an immediate decrease in rotational speed, an immediate stop of the motor, a decrease in rotational speed with a time delay, and / or a stop of the motor with a time delay. Furthermore, combinations of different responses are also possible.

[0075] In one implementation, the first routine includes stopping the motor, taking into account at least one defined and / or pre-given parameter, particularly one pre-given by the user of the handheld machine tool. Examples of such parameters include time intervals, the number of rotations of the motor, the number of rotations of the tool receiver, the rotation angle of the motor, and the number of impacts of the impact mechanism of the handheld machine tool.

[0076] In another embodiment, the first routine procedure includes changing, particularly decreasing and / or increasing, the rotational speed of the motor. This change in motor speed can be achieved, for example, by changing the motor current, motor voltage, battery current, or battery voltage, or by a combination of these measures.

[0077] In one embodiment of the invention, the first routine includes providing visual, auditory, and / or tactile feedback to the user.

[0078] Preferably, the magnitude of the change in the motor speed can be defined by the user of the handheld machine tool. Alternatively or additionally, the change in the motor speed can also be predetermined by a target value. In this case, the term "magnitude" should be understood generally in the sense of the level of change and not just in relation to the cyclic process.

[0079] In one implementation, the change in the motor speed is performed multiple times and / or dynamically, especially separately in time and / or along a characteristic curve of speed change and / or according to the working progress of the handheld machine tool.

[0080] Furthermore, the magnitude of the change in motor speed and / or the target value of motor speed can be defined by the user of the handheld machine tool.

[0081] The first routine and / or representative parameters of the first routine can be set and / or displayed by the user through application software (“App”) or user interface (“Human-Machine Interface”, “HMI”). Furthermore, in one embodiment, the HMI can be located on the machine itself, while in other embodiments, the HMI can be located on an external device such as a smartphone, tablet, or computer.

[0082] The speed of the motor can be changed multiple times and / or dynamically, especially separately in time and / or along the characteristic curve of the speed change and / or according to the working progress of the handheld machine tool.

[0083] In one embodiment of the invention, the handheld machine tool is an impact screwdriver, particularly a rotary impact screwdriver, and the work progress to be identified includes impacts occurring when the tool receiving section no longer rotates, and / or the start or stop of impact operation, particularly rotary impact operation.

[0084] Those skilled in the art will recognize that the method according to the invention enables the identification of work progress independently of at least one set speed of the motor of the handheld machine tool, at least one operating characteristic of the motor and / or energy supply, especially at least one state of charge of the battery.

[0085] Here, the signal of the operating parameters should be understood as a time sequence of measured values. Alternatively and / or additionally, the signal of the operating parameters can also be a spectrum. Alternatively and / or additionally, the signal of the operating parameters can also be modified, such as smoothing, filtering, fitting, and the like.

[0086] In another embodiment, the signal of the operating parameters is stored as a sequence of measured values ​​in a memory, preferably a ring memory, especially a handheld machine tool.

[0087] In one method step, the progress of work to be identified is based on fewer than ten impacts of the impact mechanism of the handheld machine tool, particularly fewer than ten impact vibration cycles of the electric motor, preferably fewer than six impacts of the impact mechanism of the handheld machine tool, especially fewer than six impact vibration cycles of the electric motor, most preferably fewer than four impacts of the impact mechanism, and especially fewer than four impact vibration cycles of the electric motor. Here, the impact of the impact mechanism should be understood as the axial, radial, tangential, and / or circumferential impact of the impact element (especially the hammer) on the impact mechanism body (especially the anvil). The impact vibration cycle of the electric motor is related to the operating parameters of the electric motor. The impact vibration cycle of the electric motor can be obtained from the fluctuations in the operating parameters in the signal of the operating parameters.

[0088] According to another aspect, the present invention includes a handheld machine tool comprising an electric motor, a sensor for measuring the operating parameters of the electric motor, and a control unit, wherein the control unit is configured to perform the method according to the present invention.

[0089] The electric motor of the handheld machine tool rotates the input shaft, and the output shaft is connected to the tool receiver. The anvil is torsionally connected to the output shaft, while the hammer is connected to the input shaft, causing it to perform intermittent axial movement and intermittent rotational movement around the input shaft due to its rotational motion. The hammer intermittently strikes the anvil in this manner, thus transmitting impact and rotational pulses to the anvil and consequently to the output shaft. A first sensor transmits a first signal to the control unit, for example, to determine the motor rotation angle. Furthermore, a second sensor transmits a second signal to the control unit to determine the motor speed.

[0090] Advantageously, the handheld machine tool has a memory unit in which various values ​​can be stored.

[0091] In another embodiment, the handheld machine tool is a battery-powered handheld machine tool, particularly a battery-powered rotary impact screwdriver. This ensures the flexibility of the handheld machine tool and its independence from the power grid.

[0092] This invention enables the elimination of more cumbersome signal processing methods such as filters, signal loopback, system models (static and adaptive), and signal tracking to a large extent.

[0093] Essentially, no additional sensing devices (such as accelerometers) are required; however, these evaluation methods can also be applied to signals from other sensing devices. Furthermore, these methods can be used on other signals in other motor designs (which are sufficient even without speed detection).

[0094] In a preferred embodiment, the handheld tool is a battery-operated screwdriver, drill, impact drill, or impact drill, wherein a drill, drill bit, or various bit attachments can be used as the tool. The handheld tool according to the invention is particularly constructed as an impact screwdriver, wherein a higher peak torque is generated by the pulsed release of motor energy for screwing in or loosening screws or nuts. In this case, the transfer of electrical energy should be understood in particular as the transmission of energy to the body (Korpus) via a battery and / or via a cable-connected handheld tool.

[0095] Furthermore, depending on the chosen implementation method, the screw tool can be flexibly constructed in the direction of rotation. In this way, the proposed method can be used not only for screwing in but also for loosening screws or nuts.

[0096] Within the framework of this invention, "seeking" should particularly include measurement or recording, wherein "recording" should be understood in the sense of measurement and storage. Furthermore, "seeking" should also include feasible signal processing of the measured signal. Seeking is performed, for example, by classifying or clustering the signal.

[0097] Furthermore, "judgment" should also be understood as identification or detection, where an explicit correspondence should be achieved. "Identification" should be understood as the identification of partial conformity with the sample (Muster), which can be achieved, for example, by fitting a signal to the sample, Fourier analysis, or the like. "Partial conformity" should be understood as making the fit have an error less than a pre-given threshold, especially less than 30%, and completely, especially less than 20%.

[0098] Further features, applications, and advantages of the invention will emerge from the subsequent description of embodiments of the invention illustrated in the accompanying drawings. It should be noted that the features illustrated or shown in the drawings constitute the subject matter of the invention in themselves or in any combination thereof, regardless of their generalization in the claims or their references thereto, and are merely illustrative features regardless of their representation or display in the specification or drawings, and are not intended to limit the invention in any way. Attached Figure Description

[0099] The invention will now be explained in more detail with reference to preferred embodiments. The accompanying drawings are schematic and illustrate:

[0100] Figure 1 A schematic diagram of a handheld power tool;

[0101] Figure 2(a) shows the progress of the first example application and the corresponding signals for the operating parameters;

[0102] Figure 2(b) shows the consistency between the signals of the operating parameters shown in Figure 2(a) and the model signals;

[0103] Figure 3 The second example application's progress and the two corresponding signals for the running parameters;

[0104] Figure 4 The signal variation curves of the operating parameters of the second example application according to two embodiments of the present invention;

[0105] Figure 5 The signal variation curves of the operating parameters of the second example application according to two embodiments of the present invention;

[0106] Figure 6 The third example application's progress and the two corresponding signals for the running parameters;

[0107] Figure 7 The variation curves of the signals of two operating parameters in a third example application according to two embodiments of the present invention;

[0108] Figure 8 The variation curves of the signals of two operating parameters in a third example application according to two embodiments of the present invention;

[0109] Figures 9(a) and 9(b) are schematic diagrams of two different records of the signals of the operating parameters;

[0110] Figure 10(a) Signals of operating parameters;

[0111] Figure 10(b) shows the amplitude function of the first frequency contained in the signal in Figure 10(a).

[0112] Figure 10(c) shows the amplitude function of the second frequency contained in the signal in Figure 10(a).

[0113] Figures 11(a) and 11(b) are combined diagrams of the signal with the operating parameters and the output signal of the bandpass filter based on the model signal;

[0114] Figures 12(a) to 12(d) show the combined output of the signal with the operating parameters and the frequency analysis output based on the model signal;

[0115] Figures 13(a) and 13(b) are combined plots of the signals for the operating parameters and the model signals used for parameter estimation; and

[0116] Figures 14(a) to (f) show the combined signals of the operating parameters and the model signals used for cross-correlation. Detailed Implementation

[0117] Figure 1 A handheld power tool 100 according to the present invention is shown, the handheld power tool having a housing 105 with a handle 115. According to the illustrated embodiment, the handheld power tool 100 can be mechanically and electrically connected to a battery pack 190 for independent power supply from the mains. Figure 1 In this invention, the handheld power tool 100 is exemplarily constructed as a battery-powered rotary impact screwdriver. However, it should be noted that the invention is not limited to battery-powered rotary impact screwdrivers, but is in principle applicable to handheld power tools 100 such as impact drills, in which the identification of work progress is required.

[0118] An electric motor 180 and a transmission 170, powered by a battery pack 190, are arranged within housing 105. The electric motor 180 is connected to an input shaft via the transmission 170. Furthermore, a control unit 370 is arranged within housing 105 in the area of ​​the battery pack 190. This control unit influences the electric motor 180 and transmission 170, for example, by means of a set motor speed n, a selected rotational pulse, a desired transmission gear x, or similar parameters, in order to control and / or regulate them.

[0119] The electric motor 180 can be operated (i.e., turned on and off) via a manual switch 195 and can be any type of motor (e.g., an electronically commutated motor or a DC motor). Essentially, the electric motor 180 can be electronically controlled or regulated, enabling not only reversible operation but also the achievement of pre-defined parameters regarding the desired motor speed n and the desired rotational pulses. The operating principles and constructions of suitable electric motors are well known from the prior art, and therefore detailed descriptions are omitted here for the sake of brevity.

[0120] The tool receiving section 140 can be rotatably supported in the housing 105 via the input and output shafts. The tool receiving section 140 is used to receive tools and can be directly molded onto the output shaft or connected to the output shaft in the form of a sleeve.

[0121] The control unit 370 is connected to a current source and configured to electronically control or regulate the motor 180 using different current signals. Different current signals ensure different rotational pulses of the motor 180, wherein the current signals are transmitted to the motor 180 via control wires. The current source can be configured, for example, as a battery, or as a battery pack 190 as shown in the illustrated embodiment, or as a power grid plug.

[0122] Furthermore, operating elements (not shown in detail) can be set to configure different operating modes and / or the rotation direction of the motor 180.

[0123] According to one aspect of the invention, a method for operating, for example, in Figure 1 The method of the handheld power tool 100 shown can determine whether tightening performed by the handheld power tool is performed as required, wherein the determination is based at least in part on the evaluation of the recorded signals of the motor.

[0124] Some aspects of this method are based in particular on the examination of signal patterns and the determination of the degree of conformity of these signal patterns, which can correspond to, for example, an assessment of the continued rotation of an element driven by a handheld machine tool 100, such as a screw.

[0125] In this regard, Figure 2(a) shows the application of a loose fastening element, such as a self-tapping concrete screw 900, in a fastening carrier, such as a concrete member 902 made of reinforced concrete.

[0126] Within the framework of this disclosure, performing such tightening is referred to as method step S1.

[0127] Furthermore, Figure 2 shows an example signal 200 for the operating parameters of the motor 180 of the rotary impact screwdriver, which appears in the established use of the rotary impact screwdriver in such a form or similar manner. The following embodiments relate to the rotary impact screwdriver, but they are also applicable within the framework of this invention to other hand-held machine tools 100, such as impact drills.

[0128] Within the currently disclosed framework, the signal 200 that provides the operating parameters of the motor 180 is referred to as method step S2. In this context, "providing" means making the corresponding feature available in the internal or external memory of the handheld machine tool 100.

[0129] According to the present invention, in step S3, the recorded signal 200 of the operating parameters of the motor 180 is evaluated. The basis of this evaluation is explained below, in particular with reference to Figures 2(a) and 2(b). In step S4, it is determined whether tightening has been performed as required, wherein this determination is based at least in part on the evaluation of the recorded signal 200 of the operating parameters of the motor 180.

[0130] In the current embodiment of Figure 2, time is plotted as a reference parameter on the horizontal axis x. However, in an alternative embodiment, parameters associated with time are plotted as reference parameters, such as the rotation angle of the tool receiving unit 140, the rotation angle of the motor 180, acceleration, jerk, and especially higher-order jerk, power, or energy. In the figures, the motor speed n at each time point is plotted on the vertical axis f(x). Instead of the motor speed, other operating parameters associated with the motor speed can also be selected. In an alternative embodiment of the invention, f(x) represents, for example, a signal of the motor current.

[0131] The motor speed and motor current are the following operating parameters: these operating parameters are typically and without additional cost detected by the control unit 370 in the handheld machine tool 100.

[0132] In a preferred embodiment of the invention, the user of the handheld machine tool 100 can choose which operating parameters to base the method of the invention on.

[0133] As can be seen in Figure 2(a), the signal includes a first region 310, characterized by a monotonous increase in motor speed and a range of relatively constant motor speed, which can also be referred to as a plateau. The intersection of the horizontal axis x and the vertical axis f(x) in Figure 2(a) corresponds to the start of the rotary impact screwdriver during the tightening process.

[0134] In the first region 310, the concrete screw 900 reaches the concrete member 902 with relatively little resistance, and the torque required for screwing in is below the release torque of the rotary impact mechanism. That is, the change curve of the motor speed in the first region 310 corresponds to the operating state of the screw without impact.

[0135] As can be seen from Figure 2(a), the head of the concrete screw 900 is not flat on the concrete member 902 in region 322. This means that the concrete screw 900, driven by a rotary impact screwdriver, rotates further with each impact. As the work continues, this additional rotation angle can become smaller, which is reflected in the figure by the decreasing cycle duration. Furthermore, further screwing in is also evident in the average decrease in rotational speed.

[0136] The deeper the concrete screw 900 penetrates into the concrete member 902, the higher the impact frequency. The motor speed then fluctuates with this impact frequency. The higher the impact frequency, the lower the motor speed becomes. What was initially considered a "soft tightening" situation increasingly becomes a "hard tightening" situation.

[0137] Next, if the head of the concrete screw 900 reaches the concrete member 902, even higher torque and therefore more impact energy are required for further screwing. However, because the handheld power tool 100 no longer provides impact energy, the concrete screw 900 either stops rotating or only continues to rotate by a significantly smaller angle.

[0138] The rotary impact-type operation implemented in the second region 322 and the third region 324 is characterized by the oscillation variation curve of the operating parameter signal 200, wherein the oscillation shape can be, for example, trigonometric or otherwise. In the present case, the oscillation has the following variation curve: the variation curve can be referred to as a modified trigonometric function. This characteristic shape of the operating parameter signal 200 in the impact-type helical operation is generated by the dragging and idling of the impact mechanism's impact element and the system chain (especially gear 170) located between the impact mechanism and the motor 180.

[0139] As can be seen from the above, in principle, the signal pattern corresponding to a single work progress, such as the start of impact operation, is characterized by representative features defined as follows: these features are at least partially given in advance by the inherent characteristics of the rotary impact screw machine.

[0140] In embodiments of the present invention, when determining whether tightening has been performed as required, the identification of work progress is taken into consideration. In embodiments of the present invention, one or more work progresses to be detected can be defined, and in the detection of work progress, it is determined in method step S4 that tightening has not been performed as required.

[0141] In other words, in embodiments of the present invention, the determination of whether tightening has been performed as required is based at least in part on the progress of work detected at the end of tightening.

[0142] For example, if it is determined that the progress of the work at the end of the tightening process corresponds to the following state: in which the screw head, which is already lying flat on the fastening carrier, is further rotated, this can serve as an indication that the threads with slots or notches in the bottom of the screw are at least partially damaged, and that the tightening was not performed as required.

[0143] In such a case, the characteristic of work progress that is not tightened as specified is that while the impact frequency continues to increase during the spiral process, a decrease in the impact frequency is recorded; that is, while the speed amplitude decreases, an increase in the motor speed is recorded.

[0144] In an embodiment of the method according to the invention, a model signal pattern 240 is provided in step S31 based on the following understanding. Here, the model signal pattern 240 may correspond to the following work progress, such as realizing that the head of the concrete screw 900 is flat on the concrete member 902, and in association with some embodiments of the invention, the model signal pattern 240 is also referred to as a state-typical model signal pattern. In other words, the model signal pattern 240 includes characteristics typical for work progress, such as vibration variation curves, vibration frequencies or vibration amplitudes, or the existence of individual signal sequences in a continuous, quasi-continuous, or discrete form.

[0145] In other applications, the progress of the work to be detected can be characterized by a signal pattern different from that of vibration, for example, by discontinuities or growth rates in the function f(x). In this case, the typical model signal pattern of the state is characterized precisely by this parameter rather than by vibration.

[0146] In a preferred configuration of the method of the present invention, the typical state model signal format 240 can be specified by the user in method step S31. The typical state model signal format 240 can also be stored internally in the device or provided by an external data device.

[0147] In an embodiment of the invention, in method step S32 of the method according to the invention, the signal 200 of the operating parameters of the motor 180 is compared with the typical state model signal pattern 240. In the context of the invention, the term "comparison" should be interpreted broadly and in the sense of signal analysis, so that the result of the comparison can be, in particular, a partial or gradual correspondence between the signal 200 of the operating parameters of the motor 180 and the model signal pattern 240, wherein the degree of correspondence between the two signals can be determined by different mathematical methods, which will be mentioned later.

[0148] Furthermore, in step S32, a conformity assessment is performed on the signal 200, which is used to obtain the operating parameters of the motor 180, and the typical state model signal pattern 240, and a conclusion is drawn regarding the conformity of the two signals. Here, the conformity assessment can be performed at least in part based on a conformity threshold, which can also be understood as the minimum conformity between the operating parameter signal 200 and the model signal pattern 240, and will be explained in more detail below.

[0149] Figure 2(b) shows the variation curve of the function q(x) of the conformity assessment 201 corresponding to the signal 200 of the operating parameters in Figure 2(a), which gives the value of conformity between the signal 200 of the operating parameters of the motor 180 and the typical model signal morphology 240 of the state at various positions on the x-axis.

[0150] In the current embodiment of the insertion of the concrete screw 900, this assessment can be taken into account to determine the extent of continued rotation upon impact. In this embodiment, the model signal pattern 240 provided in step S31 corresponds to an ideal impact without continued rotation, i.e., the state in which the head of the concrete screw 900 rests flat on the surface of the concrete member 902, as shown in region 324 of FIG. 2(a). Correspondingly, a high consistency of the two signals is generated in region 324, which is reflected by the high value maintained by the function q(x) of the consistency assessment 201. Conversely, only a small consistency value is achieved in region 310 (where each impact is accompanied by a high rotation angle of the concrete screw 900). The less the concrete screw 900 continues to rotate during impact, the higher the conformity. This can be seen in the function q(x) of conformity assessment 201 in region 322 when using the impact mechanism, which is characterized by the concrete screw 200 rotating at a continuously decreasing angle with each impact due to the increased screwing resistance.

[0151] As can be seen in the embodiment of Figure 2, the conformity assessment 201 of the signal used for impact differentiation is well-suited for this due to its more or less abrupt changes, wherein such abrupt changes depend on the similarly more or less abrupt changes in the continued rotation angle of the concrete screw 900 at the end of the exemplary work process. Work progress can be identified at least in part based on a comparison of the conformity assessment 201 with a conformity threshold, marked by the dashed line 202 in Figure 2(b). In the current embodiment of Figure 2(b), the intersection point SP of the function q(x) of the conformity assessment 201 and line 202 corresponds to the work progress of the concrete screw 900's head lying flat on the surface of the fastening carrier 902.

[0152] In method step S33 of the method according to the invention, progress of work is now identified, at least in part, based on the conformity assessment 201 obtained in method step S32. It should be noted that this function is not limited to screw-in applications but also includes use in screw-out applications.

[0153] Advantageously, the identification of work progress performed in step S33 is supplemented by another method step in which the first routine of the handheld machine tool 100 is implemented at least in part based on the work progress identified in method step S33, as will be described below.

[0154] In addition to determining whether tightening has been performed as required, the methods in these implementations support users in performing tightening as required by automating the tightening process.

[0155] Here, it is assumed that, as a result of the handheld machine tool performing the previously mentioned first routine, the work progress to be identified is defined by the parameter model signal morphology 240 and / or a threshold of conformity. However, similarly, in an alternative implementation, the first routine is estimated by means of known application conditions (with similar characteristics) in unknown application situations.

[0156] Although switching to impact operation results in a decrease in rotational speed, this is extremely difficult to achieve, for example, with small wood screws or self-tapping screws, to prevent the screw head from penetrating the material. This is because, even with increased torque, the high shaft speed occurs due to the impact of the impact mechanism.

[0157] This behavior is Figure 3 As shown in Figure 2, time is plotted on the horizontal axis x, while motor speed is plotted on the vertical axis f(x) and torque g(x) is plotted on the vertical axis g(x). Therefore, curves f and g give the curves of the change of motor speed f and torque g over time. Figure 3 In the lower region, similar to that shown in Figure 2, different states are schematically illustrated during the screwing process of concrete screws 900, 900' and 900'' into concrete slab 902.

[0158] In the accompanying drawings, the "shock-free" operating state is indicated by reference numeral 310, in which the screw rotates at a high speed f and a small torque g. In the "shock" operating state, indicated by reference numeral 320, the torque g increases rapidly, while the speed f decreases only slightly, as already noted above. Figure 3 Region 310' in the figure indicates the region in which the impact identification, as explained in connection with Figure 2, occurs.

[0159] To prevent the concrete screw 900 from continuing to rotate when its head contacts the concrete member 902 (which typically results in damage to the threads cut into the concrete slab 902), in embodiments of the invention, appropriate application-related routines or responses of the tool can be implemented, at least in part, based on the progress of work identified in method step S33. These responses may include machine shutdown, changes in the rotational speed of the motor 180, and / or optical, acoustic, and / or tactile feedback to the user of the handheld tool 100.

[0160] In one embodiment of the invention, the first routine includes stopping the motor 180 while taking into account at least one defined and / or pre-given parameter, especially one pre-given by the user of the handheld machine tool.

[0161] For example, in Figure 4 The diagram schematically illustrates the immediate stop of the device after impact identification 310', thereby supporting the user in preventing the concrete screw 900 from continuing to rotate while the screw head rests flat on the concrete member 902. In the accompanying drawings, this is illustrated by the rapidly descending branch f' of graph f after region 310'.

[0162] An embodiment for parameters that are defined and / or predefined, especially predefined by the user of the handheld machine tool 100, is a user-defined time after which the device stops. Figure 4 The middle period T Stopp (As shown) and the branch f'' to which curve f belongs. Ideally, the handheld machine tool 100 stops just enough so that the screw head is flush with the surface of the bolt seat. However, since the time until this occurs varies depending on the application, it is advantageous that the time period T Stopp It can be defined by the user.

[0163] Alternatively or additionally, in one embodiment of the invention, the first routine includes a change, particularly a decrease and / or an increase, in the rotational speed of the motor 180, especially the rated speed (and therefore the shaft speed after impact identification). Figure 5 The following implementation is illustrated: In this implementation, the rotational speed is reduced. The handheld machine tool 100 first operates in a "no-impact" operating state 310, characterized by the change in motor rotational speed represented by graph f. After impact identification in region 310', in this embodiment, the motor rotational speed is reduced by a defined amount, as shown by graphs f' and f''.

[0164] In one embodiment of the invention, the magnitude or degree of change in the rotational speed of the motor 180 (for the...) Figure 5 The branch f of the curve f in the graph (marked by ΔD) can be set by the user. Due to the reduced rotational speed, the user has more time to react when the screw head approaches the surface of the fastening carrier 902. Once the user deems the screw head sufficiently flush with the support surface, he can stop the handheld power tool 100 using a switch. Compared to the handheld power tool 100 stopping after impact detection, the change in motor speed (in Figure 5 The embodiment of the reduction has the following advantages: the routine is largely independent of the application situation due to the user-defined shutdown.

[0165] In one embodiment of the invention, the magnitude ΔD of the change in the rotational speed of the motor 180 and / or the target value of the rotational speed of the motor 180 can be defined by the user of the handheld machine tool 100, which further enhances the flexibility of the routine in terms of its applicability to very different application scenarios.

[0166] In embodiments of the present invention, the rotational speed of the motor 180 is changed multiple times and / or dynamically. In particular, it is possible to set the rotational speed of the motor 180 to be changed in time separately and / or along a characteristic curve of rotational speed change, and / or according to the working progress of the handheld machine tool 100.

[0167] Examples of this include, in particular, combinations of speed reduction and speed increase. Furthermore, different routines or combinations thereof can be executed at time-staggered intervals relative to impact detection. The invention also includes embodiments where time deviations are established between two or more routines. For example, if the motor speed is reduced directly after impact detection, the motor speed can be increased again after a predetermined time value. Furthermore, embodiments are provided where not only the different routines themselves, but also the time deviations between routines are predetermined by characteristic curves.

[0168] As mentioned at the outset, the present invention includes the following embodiments: in said embodiments, the progress of work is characterized by a change from an "impact" operating state in region 320 to a "non-impact" operating state in region 310, which in Figure 6 This is explained intuitively.

[0169] This transition in the operating state of the handheld power tool 100 occurs, for example, during the following work process: the concrete screw 900 disengages from the fixed carrier 902, i.e., during the unscrewing process, which in... Figure 6 The lower region is shown schematically. (As also...) Figure 3 Like in the middle, in Figure 6 In the diagram, curve f represents the motor speed at 180°, while curve g represents the torque.

[0170] As explained in connection with other embodiments of the invention, here, the operating state of the handheld machine tool (in the present case, the operating state of the impact mechanism) is also detected by finding representative signal patterns.

[0171] In the "impact" operating state (in) Figure 6 In region 320, the concrete screw 900 does not rotate and a high torque g exists. In other words, in this state, the shaft speed is zero. Under "impact-free" operating conditions (in... Figure 6In the middle (i.e., in region 310), the torque g drops rapidly, which in turn leads to a similarly rapid increase in the shaft speed and the motor speed f. Due to this rapid increase in motor speed f (caused by the decrease in torque g from the point when the concrete screw 900 is loosened from the concrete member 902), it is usually difficult for the user to receive the loosened concrete screw 900 or nut and prevent it from falling off.

[0172] The method of the present invention can be used to prevent a threaded device (which may be a concrete screw 900 or a nut) from falling off due to rapid unscrewing after the concrete component 902 has been loosened. For this purpose, see reference... Figure 7 . Figure 7 In terms of the axes and curves shown, they are basically the same as those shown. Figure 6 The corresponding reference numerals specify the corresponding features.

[0173] In one implementation, the routine includes determining that the handheld machine tool 100 has identified the progress of the work to be identified (in this embodiment, a "shock-free" operating mode, which is...). Figure 7 The handheld machine tool 100 stops immediately after the steep drop in the branch f' of the motor speed curve f in region 310. In an alternative embodiment, time T Stopp It can be defined by the user at the time T Stopp The equipment then stops. This is illustrated in the accompanying drawings by branch f'' of the motor speed curve f. Those skilled in the art will recognize that the motor speed, as well as... Figure 6 The data shown initially increased rapidly after the transition from region 320 (“impact” operating state) to region 310 (“non-impact” operating state) and continued to increase during time period T. Stopp After it ends, it descends steeply.

[0174] During time period T Stopp When properly selected, it is feasible to reduce the motor speed to "zero" precisely when the concrete screw 900 or nut is still in the thread. In this case, the user can remove the concrete screw 900 or nut with a small amount of thread rotation, or alternatively leave it in the thread to, for example, open the clamp.

[0175] The following is based on Figure 8 Another embodiment of the invention is described below. In this case, a decrease in motor speed occurs after the transition from region 320 (“impact” operating state) to region 310 (“no-impact” operating state). In the drawings, the magnitude or degree of the decrease is expressed as Δ DThe value is given as a measure between the average motor speed f'' in region 320 and the reduced motor speed f'. In a defined embodiment, this reduction can be set by the user, particularly by providing a target value for the rotational speed of the handheld machine tool 100, the target value being... Figure 8 The middle is located at the level of branch f'.

[0176] Due to the reduced motor speed and consequently, shaft speed, the user has more time to react when the head of the concrete screw 900 loosens from the screw seat surface. Once the user believes the screw head or nut has been tightened sufficiently, he can stop the hand-held tool 100 using a switch.

[0177] and Figure 7 In the associated embodiments, the handheld machine tool 100 is stopped directly or with a delay after the transition from region 320 (“impact” operating state) to region 310 (“non-impact” operating state). Compared to this embodiment, the reduction in rotational speed has the advantage of being more independent of the application scenario, since it is ultimately the user who determines when the handheld machine tool is turned off after the rotational speed is reduced. This can be helpful, for example, in the case of long threaded rods. Here, there are application scenarios where, after the threaded rod is loosened and the impact mechanism stops accordingly, a more or less lengthy unscrewing process must still be performed. That is, turning off the handheld machine tool 100 after the impact mechanism stops is not desirable in these cases.

[0178] Furthermore, in another method step, a quality assessment of the first routine performed by the user of the handheld machine tool 100 is completed, and the routine is optimized at least in part based on the assessment by this other method step.

[0179] In some embodiments of the present invention, work progress is output to the user of the handheld tool using the output device of the handheld tool.

[0180] The following explanation relates to some technical connections and implementation methods associated with the execution of steps S2-S3.

[0181] In practical applications, it is possible to configure the method to repeatedly implement one or more of steps S2 to S32 during the operation of the handheld machine tool 100 to monitor the progress of the application. For this purpose, the obtained signal 200 of the operating parameters can be segmented in step S2, and step S32 can be performed on the signal segments, preferably always the same fixed length signal segments.

[0182] For this purpose, the signal 200 of the operating parameters can be stored as a sequence of measurement values ​​in a memory, preferably in a ring memory. In this embodiment, the handheld machine tool 100 includes a memory, preferably a ring memory.

[0183] As already mentioned in association with Figure 2, in a preferred embodiment of the invention, in method step S2, the signal 200 of the operating parameter is obtained as a time-varying curve of the measured value of the operating parameter, or as a measured value of the operating parameter (as a parameter of the motor 180 associated with the time-varying curve). Here, the measured value can be discrete, quasi-continuous, or continuous.

[0184] Here, one embodiment is set up such that the signal 200 of the operating parameter is recorded as a time change curve of the measured value of the operating parameter in method step S2, and in method step S2a following method step S2, the time change curve of the measured value of the operating parameter is transformed into a change curve of the measured value of the operating parameter as a parameter of the motor 180 associated with the time change curve (e.g., the rotation angle of the tool receiving unit 140, the motor rotation angle, acceleration, jerk, especially higher-order jerk, power or energy).

[0185] The advantages of this embodiment will now be explained with reference to Figures 9(a) and 9(b). Similar to Figure 2, Figure 9(a) shows the signal f(x) 200 of the operating parameter on the horizontal axis x (in this case, on time t). As shown in Figure 2, the operating parameter can be the motor speed or a parameter associated with the motor speed.

[0186] The figure contains two signal variation curves 200 for operating parameters, which can respectively correspond to the work progress, and in the case of a rotary impact screwdriver, correspond to, for example, a rotary impact tightening mode. In both cases, the signal includes a wavelength of a vibration variation curve that is ideally assumed to be sinusoidal, wherein the signal with a shorter wavelength T1 has a variation curve with a higher impact frequency, and the signal with a longer wavelength T2 has a variation curve with a lower impact frequency.

[0187] The two signals can be generated by the same handheld power tool 100 at different motor speeds and depend in particular on which rotational speed the user requests via the operating switch of the handheld power tool 100.

[0188] Now, for example, if we want to consider the parameter "wavelength" to define the typical model signal form 240 of the state, that is, in the current case, at least two different wavelengths T1 and T2 must be stored as possible parts of the typical model signal form of the state. Thus, the comparison between the signal 200 of the operating parameter and the typical model signal form 240 of the state in both cases results in a "match". Because the motor speed can change generally and over a large range in time, this causes the searched wavelength to change as well, and thus the method used to identify the impact frequency must be adjusted accordingly.

[0189] With a large number of possible wavelengths, the cost of methods and programming increases rapidly accordingly.

[0190] Therefore, in a preferred embodiment, the time value on the horizontal axis is converted into a value associated with time, such as acceleration, a higher-order jerk value, power, energy, frequency, the rotation angle of the tool receiver 140, or the rotation angle of the motor 180. This is feasible because the transmission ratio between the motor 180 and the impact mechanism and the rigidity of the tool receiver 140 produces a direct, known dependence of the motor speed on the impact frequency. This normalization achieves a vibration signal with an invariant period, independent of the motor speed, as shown in Figure 9(b) by the transformation of two signals belonging to T1 and T2, where the two signals now have the same wavelength P1 = P2.

[0191] Accordingly, in this embodiment of the invention, the typical model signal form 240 for all rotational speeds can be defined by a unique wavelength parameter through time-related parameters, such as the rotation angle of the tool receiving unit 140, the motor rotation angle, acceleration, jerk, especially higher-order jerk, power, or energy.

[0192] In a preferred embodiment, in method step S32, a comparison method is used to compare the signal 200 of the operating parameters, wherein the comparison method includes at least one frequency-based comparison method and / or a comparison method for performing comparisons. The comparison method compares the signal 200 of the operating parameters with a typical model signal pattern 240 of the state to determine whether it at least meets a conformity threshold. The comparison method compares the measured signal 200 of the operating parameters with a conformity threshold. The frequency-based comparison method includes at least bandpass filtering and / or frequency analysis. The comparison method for performing comparisons includes at least parameter estimation and / or cross-correlation. The frequency-based and comparison methods for performing comparisons are described in more detail below.

[0193] In an embodiment with bandpass filtering, the input signal, as described, is transformed to a time-related parameter and filtered through one or more bandpass filters, the channel regions of which correspond to one or more state-typical model signal patterns. The channel regions are generated by state-typical model signal patterns 240. It is also conceivable that the channel regions correspond to a predetermined frequency associated with state-typical model signal patterns 240. If the amplitude at this frequency exceeds a previously defined limit (as is the case when the desired work progress is achieved), the comparison in method step S32 results in the following: the signal 200 of the operating parameter equals the state-typical model signal pattern 240, and thus the desired work progress is achieved. In this embodiment, the determination of the amplitude limit can be understood as obtaining an evaluation of the consistency between the state-typical model signal pattern 240 and the signal 200 of the operating parameter, based on which it is determined in method step S33 whether the desired work progress exists.

[0194] The following implementation method will be explained with reference to Figure 10: In this implementation, frequency analysis is used as a frequency-based comparison method. In this case, the signal 200 of the operating parameter is shown in Figure 10(a) and corresponds, for example, to the time-varying curve of the rotational speed of the motor 180, which is transformed from the time domain to the correspondingly weighted frequency domain based on frequency analysis, such as Fast Fourier Transform (FFT). Here, the term "time domain" according to the above implementation method can be understood not only as "the time-varying curve of the operating parameter" but also as "the curve of the operating parameter as a time-related parameter".

[0195] This form of frequency analysis is widely known as a mathematical tool for signal analysis from multiple technical fields and is particularly used to approximate a measured signal as a series expansion of a weighted periodic harmonic function of different wavelengths. For example, in Figure 10(b) and 10(c) In the figure, the weighting factors κ1(x) and κ2(x) are given as curves 203 and 204 as functions of time: the corresponding frequencies or bands are present and how strongly they are present in the signal under examination (i.e., curve 200 of the change of the operating parameters), which are not given here for clarity reasons.

[0196] Regarding the method according to the invention, namely, by means of frequency analysis, it is possible to determine whether a frequency corresponding to the typical model signal pattern 240 of the state exists in the signal 200 of the operating parameters and at what amplitude. Furthermore, it is also possible to define a frequency whose absence is a measure of the presence of the work progress to be identified. As mentioned in connection with bandpass filtering, a limit value for the amplitude can be specified, which is a measure of the degree of conformity between the signal 200 of the operating parameters and the typical model signal pattern 240 of the state.

[0197] In the embodiment shown in Figure 10(b), for example, at time point t2 (point SP2), the amplitude κ1(x) of a first frequency, typically not found in the typical state model signal pattern 240, falls below its corresponding limit value 203(a) in the signal 200 of the operating parameters. In this embodiment, this is a necessary but insufficient criterion for identifying the presence of work progress. At time point t3 (point SP3), the amplitude κ2(x) of a second frequency, typically found in the typical state model signal pattern 240, exceeds its corresponding limit value 204(a) in the signal 200 of the operating parameters. In the relevant embodiment of the invention, the coexistence of amplitude functions κ1(x) or κ2(x) being below or above the limit values ​​203(a) and 204(a) is a decisive criterion for assessing the conformity of the signal 200 of the operating parameters with the typical state model signal pattern 240. Accordingly, in this case, it is determined in method step S33 that the work progress to be identified has been achieved.

[0198] In alternative embodiments of the invention, only one of these criteria is used, or one or two of these criteria are used in combination with other criteria, such as achieving a set speed of motor 180.

[0199] In some embodiments, a comparison method is used whereby the signal 200 of the operating parameter is compared with a typical state model signal pattern 240 to determine whether the measured signal 200 of the operating parameter has at least 50% agreement with the typical state model signal pattern 240 and thus reaches a predetermined threshold. Alternatively, it is conceivable to compare the signal 200 of the operating parameter with the typical state model signal pattern 240 to determine the mutual agreement between the two signals.

[0200] In an embodiment of the method according to the invention, parameter estimation is used as a comparison method, wherein the measured signal 200 of the operating parameters is compared with the typical state model signal pattern 240, wherein the estimated parameters are identified for the typical state model signal pattern 240. Using the estimated parameters, a measure of the conformity between the measured signal 200 of the operating parameters and the typical state model signal pattern 240 can be obtained, indicating whether the desired work progress has been achieved. Here, parameter estimation is based on adjustment calculations, which are mathematical optimization methods known to those skilled in the art. Using the estimated parameters, the mathematical optimization method adapts the typical state model signal pattern 240 to a series of measurement data of the signal 200 of the operating parameters. Based on a measure of the conformity between the typical state model signal pattern 240 parameterized with the estimated parameters and the limit values, a judgment can be made regarding whether the desired work progress has been achieved.

[0201] By using the adjustment calculation method of comparing parameter estimation, it is also possible to obtain a measure of the consistency between the estimated parameters of the typical model signal morphology 240 and the measured signal 200 of the operating parameters.

[0202] In one embodiment of the method of the present invention, in method step S32, a cross-correlation method is used as a comparison method for comparison. As with the mathematical methods described above, the cross-correlation method is known to those skilled in the art. In the cross-correlation method, a typical model signal form 240 of the state is associated with the measured signal of the operating parameter 200.

[0203] Compared to the parameter estimation method proposed above, the result of cross-correlation is a signal sequence with a length summed from the lengths of the operating parameter signal 200 and the state-typical model signal form 240, which depicts the similarity of the input signals offset in time. Here, the maximum value of the output sequence signifies the point in time of highest consistency between the two signals (i.e., the operating parameter signal 200 and the state-typical model signal form 240), and is therefore also a measure of the correlation itself, which in this embodiment is used as a criterion for determining the progress of work to be identified in method step S33. A key difference from parameter estimation in the implementation of the method according to the invention is that any state-typical model signal form can be used for cross-correlation, whereas in parameter estimation, the state-typical model signal form 240 must be representable by a parameterizable mathematical function.

[0204] Figure 11 shows the measured signal 200 of the operating parameters for use in a frequency-based comparison method using bandpass filtering. Here, time or time-related parameters are plotted as the x-axis. Figure 11(a) shows the measured signal of the operating parameters as the input signal for bandpass filtering, wherein the handheld machine tool 100 operates in a helical mode in the first region 310. In the second region 320, the handheld machine tool 100 operates in a rotary-impact mode. Figure 11(b) shows the output signal after the input signal has been filtered by the bandpass filter.

[0205] Figures 12(a) to 12(d) show the measured signal 200 for operating parameters in the case where frequency analysis is used as a frequency-based comparison method. A first region 310 is shown in Figures 12(a) and (b) where the handheld machine tool 100 is in helical operation mode. Time t or a time-related parameter is plotted on the x-axis of Figure 12(a). The signal 200 of the operating parameter is shown in Figure 12(b) in a transformed manner, wherein, for example, it can be transformed from the time domain to the frequency domain by means of a fast Fourier transform. Frequency f, for example, is plotted on the x'-axis of Figure 12(b), thus showing the amplitude of the signal 200 of the operating parameter. A second region 320 is shown in Figures 12(c) and (d) where the handheld machine tool 100 is in rotary-impact operation mode. Figure 12(c) shows the measured signal 200 of the operating parameter plotted in time in rotary-impact operation mode. Figure 12(d) shows the transformed signal 200 of the operating parameters, where the signal 200 of the operating parameters is plotted at a frequency f, which is the abscissa x'. Figure 12(d) shows a representative amplitude for rotary impact operation.

[0206] Figure 13(a) shows a typical case of a comparison method used in the first region 310 illustrated in Figure 2 to compare parameter estimates between the signal 200 of the operating parameters and the signal 240 of the typical state model using a comparison method. The typical state model signal 240 has a basic triangular variation curve, while the signal 200 of the operating parameters has a variation curve that deviates strongly from it. Regardless of the choice of one of the comparison methods described above, in this case, the comparison between the typical state model signal 240 and the signal 200 of the operating parameters performed in method step S32 results in the following: the degree of agreement between the two signals is small, so that the work progress to be identified is not identified in method step S33.

[0207] Conversely, Figure 13(b) illustrates a situation where there is a work progress to be identified, and therefore the typical model signal pattern 240 and the signal 200 of the operating parameters generally exhibit a high degree of consistency, even if deviations can be determined at individual measurement points. Therefore, in a comparative method that compares parameter estimates, a judgment can be made as to whether the work progress to be identified has been achieved.

[0208] Figures 14(a) to (f) show a comparison of the typical state model signal morphology 240 (see Figures 14(b) and 14(e)) with the measured signal 200 of the operating parameters (see Figures 14(a) and 14(d)) using cross-correlation as the comparison method. In Figures 14(a)-(f), time or time-related parameters are plotted on the x-axis. Figures 14(a)-(c) show the first region 310 corresponding to the spiral operation. Figures 14(d)-(f) show the third region 324 corresponding to the work progress to be identified. As explained above, the measured signal of the operating parameters (Figures 14(a) and 14(d)) is correlated with the typical state model signal morphology (Figures 14(b) and 14(e)). The corresponding results of the correlation are shown in Figures 14(c) and 14(f). Figure 14(c) shows the results of the association during the first region 310, where it can be seen that there is a small consistency between the two signals. Therefore, in the embodiment of Figure 14(c), it is determined in method step S33 that the work progress to be identified has not been reached. Figure 14(f) shows the results of the association during the third region 324. As can be seen in Figure 14(f), there is a high consistency, thus it is determined in method step S33 that the work progress to be identified has been reached.

[0209] This invention is not limited to the illustrated and shown embodiments. Rather, it includes all professional extensions within the framework of the invention as defined by the claims.

[0210] In addition to the embodiments described and depicted, other embodiments are conceivable: these other embodiments may include other variations and combinations of features.

Claims

1. A method for operating a handheld machine tool (100), the handheld machine tool (100) including an electric motor (180), the method comprising the following steps: S1 tightens the connecting device in the base; S2 provides at least one signal (200) of the operating parameters of the motor (180) during the tightening process. S3 The recorded signal (200) evaluates the operating parameters of the motor (180); S4 determining whether the screwing has been carried out as prescribed, wherein The judgment is based at least in part on the evaluation of the recorded signals (200) of the operating parameters of the motor (180). Step S3, which evaluates the recorded signals of the motor (180), includes the following steps: S31 provides at least one state-typical model signal form (240), wherein the state-typical model signal form (240) corresponds to the working progress of the handheld machine tool (100); S32 compares the signal of the operating parameter (200) with the typical model signal shape (240) of the state, and obtains a consistency assessment from the comparison; S33 identifies the progress of the work at least in part based on the conformity assessment obtained in method step S32.

2. The method according to claim 1, characterized in that, The operating parameter is the speed of the motor (180) or an operating parameter associated with the speed.

3. The method for operating a handheld machine tool (100) according to claim 1 or 2, characterized in that, The connecting device is a self-tapping screw.

4. The method for operating a handheld machine tool (100) according to claim 3, characterized in that, The connecting device is a self-tapping concrete screw.

5. The method for operating a handheld machine tool (100) according to claim 1 or 2, characterized in that, The base is at least partially made of concrete.

6. The method for operating a handheld machine tool (100) according to claim 5, characterized in that, The base is partially made of reinforced concrete.

7. The method for operating a handheld machine tool (100) according to claim 1 or 2, characterized in that, The method includes method steps for visualizing the evaluation of the recorded signals of the electric motor (180) on the human-machine interface (HMI) of the handheld machine tool (100).

8. The method for operating a handheld machine tool (100) according to claim 7, characterized in that, The method includes visualizing incorrect tightening.

9. The method for operating a handheld machine tool (100) according to claim 1 or 2, characterized in that, The method includes the method steps of sending a message regarding the evaluation of the recorded signals of the electric motor (180) to an external device.

10. The method for operating a handheld machine tool (100) according to claim 9, characterized in that, The message concerns an improperly handled tightening.

11. The method for operating a handheld machine tool (100) according to claim 9, characterized in that, Sending messages includes sending push messages to handheld devices.

12. The method for operating a handheld machine tool (100) according to claim 9, characterized in that, Sending messages includes sending push notifications to smartphones.

13. The method for operating a handheld machine tool (100) according to claim 1 or 2, characterized in that, The method includes method steps for recording an evaluation of the recorded signals of the electric motor (180).

14. The method for operating a handheld machine tool (100) according to claim 13, characterized in that, The method includes documenting improperly handled tightening based on a document.

15. The method for operating a handheld machine tool (100) according to claim 13, characterized in that, The method includes recording improperly handled tightening in the 3D assembly drawing.

16. The method for operating a handheld machine tool (100) according to claim 13, characterized in that, The recording method includes detecting and storing the tightened position.

17. The method for operating a handheld machine tool (100) according to claim 16, characterized in that, The position of tightening is detected and stored by using the positioning sensor of the handheld machine tool (100).

18. The method for operating a handheld machine tool (100) according to claim 1 or 2, characterized in that, The model signal pattern (240) is given in advance at the factory and / or can be given in advance and / or selected by the user.

19. The method for operating a handheld machine tool (100) according to claim 1 or 2, characterized in that, The determination of the conformity assessment in method step S32 includes comparing the conformity between the signal (200) of the running parameter and the model signal morphology (240) with at least one threshold of the conformity.

20. The method for operating a handheld machine tool (100) according to claim 1 or 2, characterized in that, In method step S2, the signal (200) of the operating parameter is recorded as a time variation curve of the measured value of the operating parameter, or as a measured value of the operating parameter on the motor (180) of the parameter associated with the time variation curve.

21. The method for operating a handheld machine tool (100) according to claim 1 or 2, characterized in that, The handheld machine tool (100) is an impact screwdriver, and the work progress to be identified is the impact when the tool receiving part does not continue to rotate.

22. The method for operating a handheld machine tool (100) according to claim 21, characterized in that, The handheld machine tool (100) is a rotary impact screwdriver.

23. A handheld machine tool (100) comprising a motor (180), a sensor for measuring the operating parameters of the motor (180), and a control unit (370), characterized in that, The control unit (370) is configured to perform the method according to any one of claims 1 to 22.

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