Method for operating an electric hand-held power tool

Abstract

A method (100) for operating an electric hand-held power tool (1) comprises the following method steps. It is checked whether the electric hand-held power tool (1) is operated in impact mode (S2). In this case, an operating current (14) of a drive motor (2) of the electric hand-held power tool (1) is compared with a predeterminable first threshold value (I T ). The electric hand-held power tool (1) is operated in impact mode (S2) when the operating current (14) is greater than the predeterminable first threshold value (I T ). It is checked whether consecutive speed values ​​(IS J ) of the drive motor (2) correspond to a predeterminable speed (IS) when the electric hand-held power tool (1) is operated in impact mode (S2). In this case, speed values ​​(IS J ) for operating current maxima (P J) of the drive motor (2) is determined and compared with the preset speed (IS). The impact operation (S2) is continued for a preset period of time and with a preset impact frequency if the successive speed values ​​(IS J ) correspond to the specified speed (IS).

Description

The present invention relates to a method for operating a hand-held electric power tool, in particular a rotary impact wrench.Methods for operating rotary impact screwdrivers are known from the prior art. A problem that arises in operating a rotary impact wrench is that a user has no possibility of consistently determining tightening torque in tightening or loosening bolts and nuts. This applies in particular when a rotary impact wrench is used over a longer period of time, since a battery voltage decreases over time and thus only a reduced tightening torque can be applied.In addition, a user will detect a significant change in the applied torque if he changes with the same rotary impact wrench, for example, from a hard connection, for example from a direct metal-to-metal connection, to a medium or soft connection, which has, for example, a metal and a connecting element with lower stiffness, for example a plastic, a rubber or wood. The torque applied to a hard connection is typically higher than a soft connection. Further, an accuracy of determining the tightening torque is lower at low speeds of the driving motor than at higher speeds. Moreover, the torque output variation is higher for soft joints than for hard joints and thus affects the quality of the joint. If the rotary impact wrench is additionally controlled only in an open control loop, i.e. without feedback of a control loop to a sensor signal, great fluctuations occur in the torque output. As tool settings change, output and consistency typically need to be calibrated, which is time consuming.It is an object of the present invention to provide an improved method for operating a hand-held electric machine tool, and a computer program product for carrying out the method, and a machine-readable storage medium on which the computer program product is stored, and an improved hand-held electric machine tool. This object is achieved by a method for operating a hand-held electric machine tool, a computer program product for carrying out the method, a machine-readable storage medium on which the computer program product is stored, and an electric hand-held electric machine tool having the features of the respectively independent claims. Advantageous further developments are specified in dependent claims.A method for operating a hand-held electric machine tool, in particular a rotary impact wrench, comprises the following method steps. It is checked whether the electric hand-held power tool is operated in a percussion mode. In this case, an operating current of a drive motor of the electric hand-held power tool is compared with a predefinable first threshold value. The electric hand-held power tool is operated in the percussion mode when the operating current is greater than the predefinable first threshold value. It is checked whether successive speed values of the drive motor correspond to a predefinable speed when the electric hand-held power tool is operated in the percussion mode. In this case, speed values for operating current maxima of the drive motor are determined and compared with the predefinable speed. The percussion operation is continued for a predeterminable period of time and at a predeterminable percussion frequency if the successive speed values correspond to the predeterminable speed.The electric hand-held power tool can be designed as a rotary impact wrench or as another electric device. The electric hand-held power tool is designed to set a tool holder in rotation in order to perform a work, for example for screwing or releasing screws and nuts or another work in which a torque must be generated. In addition, the electric hand-held power tool is designed to exert rotary impacts on the tool holder. For this purpose, the electric hand-held power tool has a rotary impact hammer mechanism which is arranged on a shaft which is coupled to the drive motor and the tool holder via an anvil.Advantageously, the method enables a reliable and stable connection to be established with a provided tightening torque. This is ensured in that the percussion operation takes place with speed values corresponding to the predeterminable speed, the predeterminable time duration and the predeterminable percussion frequency, whereby the tightening torque can be reproduced consistently and, for example, independently of a voltage of a battery of the electric hand-held power tool. In comparison, in known rotary impact screwdrivers, a constant tightening torque cannot be provided with decreasing battery voltage. For determining the speed of the drive motor, a Hall sensor can be used, for example, which delivers a relationship between a rotation angle and the speed for connections of different hardness.The percussion operation is initially determined in that the operating current exceeds the predefinable first threshold value. However, the percussion operation is only continued for the predeterminable period of time when the speed values correspond to the predeterminable speed. For example, it may be sufficient that three successive speed values assume the value of the predeterminable speed. A speed corresponds to the predeterminable speed, for example, exactly when it has a value which deviates from the predeterminable speed by at most five percent. Within the scope of such a fluctuation of the speed of the drive motor, this can be assumed to be constant. However, another threshold value may be adopted in which a speed fluctuation is considered to be constant. If a plurality of speed values correspond to the predefinable speed, this is interpreted as a consistent impact operation.The percussion operation is only ended when the predeterminable period of time has elapsed, since, taking into account the predeterminable speed, a certain period of time is required in which the electric hand-held power tool has to be operated in the percussion operation in order to bring about a desired tightening torque. A predefinable frequency of rotary impacts during the impact operation of the electric hand-held power tool and thus a frequency at which speed values occur, in combination with the predefinable time duration, determines a number of rotary impacts that take place during the impact operation.In one embodiment, it is checked whether further speed values correspond to the predefinable speed as long as the percussion operation is continued. The operation of the electric hand-held power tool is terminated prematurely if the further speed values do not assume the value of the predeterminable speed. Alternatively, the percussion operation is continued until the predeterminable period of time is exceeded if the further speed values correspond to the predeterminable speed. Advantageously, the speed of the drive motor is monitored in the region of its local maxima and the percussion operation is only terminated prematurely if a deviation occurs. This can prevent, for example, a connection from being established with a torque differing from a required tightening torque.In one embodiment, before checking the speed value values, it is checked whether the operating current has a first operating current maximum in the percussion mode. If the operating current in the percussion mode does not have a first operating current maximum, a check is made as to whether a lead time of the electric hand-held power tool has elapsed. In one specific embodiment, it is checked whether a lead time of the electric handheld power tool has elapsed if the speed values do not correspond to the predefinable speed. Advantageously, it is possible to investigate whether the operating current assumes unusual values for the lead time within the lead time. This could possibly damage a connection to be produced.In one specific embodiment, it is checked whether a slope of the operating current within the lead time is greater than a predefinable second threshold value if the lead time has not elapsed. The operation of the electric hand-held power tool is terminated prematurely if the gradient of the operating current is greater than the second threshold value. If the operating current has a slope within the lead time that is greater than the second threshold value, this is evaluated as an attempt to carry out a work that has already taken place again. For example, it may be that a screw connection already tightened with desired tightening torque is incorrectly tightened again. As a result, the screw connection and / or components to be connected to one another can be damaged. This can advantageously be prevented by detecting such a process in good time by monitoring the gradient of the operating current within the lead time. An unusual increase in the operating current is therefore evaluated, for example, to the effect that a screw connection is tightened again. In this case, the operation is terminated prematurely. If the gradient does not exceed the second threshold value, it is checked again whether the lead time has elapsed until the second threshold value is exceeded.In one embodiment, it is checked whether a user of the electric hand-held power tool actuates an activation switch of the electric hand-held power tool if the operating current is less than the predefinable first threshold value. The operation of the electric hand-held power tool is ended prematurely if the user no longer actuates the activation switch. It is checked again whether the operating current is greater than the predefinable first threshold value when the user actuates the activation switch.In one embodiment, it is indicated that the predeterminable period of time has been exceeded or that the operation of the electric hand-held power tool has been terminated prematurely. Advantageously, a screw connection state is thereby displayed to the user, for example. If the predeterminable time duration has been exceeded, the tightening torque has been reached and a reliable screw connection has been produced. The operation of the electric hand-held power tool is terminated prematurely if the further speed values do not correspond to the predeterminable speed, the gradient of the operating current is greater than the second threshold value or the user no longer actuates the activation switch. The information mentioned can be displayed, for example, by means of light-emitting diodes of the electric hand-held power tool. Alternatively or additionally, different acoustic signals can also indicate whether the predefined time duration has been exceeded or whether the operation of the electric hand-held power tool has been ended prematurely.In one embodiment, the method comprises the following further method step. A further phase of the percussion operation is initiated after the elapse of the predeterminable period of time. Within the further phase of the percussion operation, the electric hand-held power tool is operated for a predeterminable further time duration and at a predeterminable further percussion frequency in such a way that additional speed values correspond to a predeterminable further speed. The additional speed values are determined for additional operating current maxima of the drive motor and compared with the predefinable further speed. Advantageously, the electric hand-held power tool is operated in this case in a dual impact mode at different speeds of the drive motor. As a result, the tightening torque can be controlled even more precisely.In one embodiment, the predeterminable further speed is greater than the predeterminable speed. For example, the predefinable speed can be reduced by ten to seventy percent compared to the predefinable further speed. As a result, hard connections requiring a comparatively high tightening torque can be reliably produced, for example, by gradually building up the torque using two maximum values for the speed of the drive motor in different strike phases. In a further embodiment, more than two impact phases can also be carried out or carried out, wherein in each case different speeds can be preset for the speed values and time periods.In one embodiment, the predeterminable speed, the predeterminable time duration and the predeterminable impact frequency are predetermined as a function of a degree of hardness of components to be connected by means of the electric hand-held power tool. As a result, the tightening torque can advantageously be adapted to a hard, soft or intermediate compound to be produced. In the case of a hard connection, the striking operation can be continued for 0.1 to 0.3 seconds, for example. In the case of an intermediate compound, it may be necessary for the striking operation to be continued for 0.1 to 1 second, for example. In the case of a soft connection, the striking operation may be continued for 0.5 to 1.5 seconds, for example. The values mentioned are merely to be understood as exemplary details and are not restrictive. Other time periods may also be chosen for different connections. This advantageously ensures that its tightening torque can also be applied precisely and reproducibly for different connections. Accordingly, the predeterminable further speed, the further time duration and the further impact frequency in the further phase of the impact operation can also be predetermined as a function of the degree of hardness. The components to be connected are to be understood as components of a screw connection and / or materials to be screwed together, i.e. for example a screw and a nut as components of the screw connection, and metal and wood as materials to be connected together by means of the screw connection.In one embodiment, the predefinable speed is predefined as a function of a battery voltage of a battery of the electric hand-held power tool. For example, the predefinable speed may increase linearly below a predefinable battery voltage and may be constant above the predefinable battery voltage. The predeterminable further speed can also be predetermined as a function of the battery voltage.In one embodiment, the drive motor is actuated in a pulse width modulated manner. Advantageously, the speed of the drive motor can be precisely controlled in the percussion mode and optionally in the further phase of the percussion mode. As a result, the speed can be kept particularly constant during the percussion operation.A computer program product includes instructions that, when executed by a processor, cause the processor to perform a method according to any of the embodiments. The computer program product is stored on a machine-readable storage medium.An electric hand-held power tool has a drive motor for driving a tool holder, a current sensor for detecting an operating current of the drive motor, a speed sensor for detecting a speed of the drive motor, and a controller for actuating the drive motor and for receiving and evaluating sensor signals of the current sensor and of the speed sensor. The controller is designed to check whether the electric hand-held power tool is operated in a percussion mode, wherein an operating current of the drive motor of the electric hand-held power tool is compared with a predefinable first threshold value, wherein the electric hand-held power tool is operated in a percussion mode if the operating current is greater than the first threshold value, and whether successive speed values of the drive motor are at a predefinable speed if the electric hand-held power tool is operated in a percussion mode, and to continue the percussion mode for a predefinable time duration and at a predefinable percussion frequency if the successive speed values correspond to the predefinable speed.The electric hand-held power tool and the method for operating the electric hand-held power tool are explained in detail below in conjunction with schematic drawings. The following are shown: FIG. 1 : components of a hand-held electric machine tool; FIG. 2 : shows an exemplary speed and operating current profile of a drive motor of the electric hand-held power tool within the scope of a method for operating the electric hand-held power tool; FIG. 3 : shows a further exemplary speed and operating current profile of the drive motor within the scope of the method for operating the electric hand-held power tool; FIG. 4 : different speeds of the drive motor for different applications; FIG. 5 : different speeds of the drive motor as a function of a battery voltage; FIG. 6 : shows an exemplary sequence of a method for operating the electric hand-held power tool; and FIG. 7 shows an exemplary statistic regarding a quality of results achieved by means of the electric hand-held power tool.FIG. 1 schematically shows an electric hand-held power tool 1. the electric hand-held power tool 1 has a drive motor 2 for driving a tool holder 3. The tool holder 3 can be designed, for example, to hold a nut or a helical bit. In this case, the electric hand-held power tool 1 is designed, for example, as a rotary impact wrench 1.The drive motor 2 is designed to rotate the tool holder 3 about a longitudinal axis of the tool holder 3. The tool holder 3 is connected to an anvil 4 or has an anvil 4, i.e. the anvil 4 is monolithically connected to a tool holder element of the tool holder 3. The anvil 4 is connected to a rotary impact hammer mechanism 5 which comprises a rotary impact hammer. In the impact mode, the anvil 4 rotates with the rotary impact hammer. As a result, the tool holder 3 can be driven in a pulse-like manner in order to exert torque impacts on the tool holder 3. As a result, a tightening torque can be built up. The rotary percussion hammer mechanism 5 is connected via an intermediate shaft to a transmission 6. The transmission 6 is connected to the drive motor 2 via a shaft.For controlling the drive motor 2, the electric hand-held power tool 1 has a controller 7 and a battery 8 connected to the controller 7. The controller 7 is configured to rotate the drive motor 2 by applying an electric voltage to the drive motor 2. The drive motor 2 can be, for example, an electronically commutated motor (EC motor for short). The controller 7 can be designed to actuate the drive motor 2 by means of pulse width modulation (PWM). In pulse width modulation, an input voltage is typically modulated by means of a periodic sawtooth or square wave voltage, as a result of which a speed of the drive motor 2 can be controlled in a targeted manner. For example, this can produce a modulated input signal that is sinusoidal.The electric hand-held power tool 1 further has a current sensor 9 for detecting an operating current of the drive motor 2 and a speed sensor 10 for detecting a speed of the drive motor 2. The current sensor 9 and the speed sensor 10 are connected to the controller 7. The controller 7 is designed to receive and evaluate sensor signals of the current sensor 9 and of the speed sensor 10. The speed sensor 10 can be designed, for example, as a Hall sensor. The speed sensor 10 is configured to determine the rotational speed of the drive motor 2 by measuring a rotational angle.The electric hand-held power tool 1 also has a user interface 11 which is connected to the controller 7. The user interface 11 is provided, for example, for a user to be able to select settings of the electric hand-held power tool 1. For example, it is possible that a striking mode of the electric hand-held power tool 1 can be set via the user interface 11. The impact mode can be selected depending on the operation to be performed. For example, different impact modes can be provided for different degrees of hardness of connections, for example for soft and hard screw connections and / or materials to be connected to one another.An activation switch 12 is connected to the controller 7 and is provided to activate operation of the drive motor 2 or of the electric hand-held power tool 1. In addition, the electric hand-held power tool 1 has a display device 13. The display device 13 can comprise, for example, a plurality of light-emitting diodes which are designed to emit different signal colors. As a result, for example, a screw connection state can be displayed. A successfully completed working process, in which, for example, a predeterminable tightening torque has been applied to a screw connection, can be indicated, for example, by means of a green light-emitting diode. A premature termination of the operation of the electric hand-held power tool 1 can be indicated, for example, by means of a red light-emitting diode. In addition, different categories can be displayed by providing the light emitting diodes to emit light permanently or in a pulsed manner depending on the cause of the premature termination of the operation of the electric hand-held power tool 1. The display device 13 can also be omitted. Alternatively, acoustic devices can be provided which are designed to generate different signal tones depending on the state of a screw connection.FIG. 2 schematically shows an exemplary operating current profile 14 and an associated speed profile 15 of the drive motor 2 of the electric hand-held power tool 1 within the scope of a method for operating the electric hand-held power tool 1.The operating current profile 14 and the speed profile 15 can each be divided into two zones S 1, S 2. In a zone S 2, a beating operation is performed, while in a preceding zone S 1, no beating operation is performed. The percussion mode is also denoted by the reference symbol S 2 below. In the percussion mode S 2, the tool holder 3 is driven in a pulsed manner. At a time t S the operating current 14 exceeds a predefinable threshold value I T. This defines the start of the percussion operation S 2 of the electric hand-held power tool 1, i.e. zone S 2 begins at the time t S. The operating current 14 increases in this region due to a resistance, for example a resistance of a screw connection. In the context of the first method step, the operating current 14 is compared with the predefinable first threshold value I T. The electric hand-held power tool 1 is operated in the percussion mode S 2 if the operating current 14 is greater than the predefinable first threshold value I T.In a second method step, it is checked whether successive speed values IS J of the drive motor 2 correspond to a predefinable speed ISwhen the electric hand-held power tool 1 is operated in percussion operation. The operating current 13 increases between t S and a subsequent time t 2 and has a first local operating current maximum P 1 at the time t 2. Since rotary blows are periodically exerted during percussion operation, the operating current 14 is periodic and has a plurality of local operating current maxima P J with a predefinable percussion frequency. In the percussion mode S 2, the operating current 14 is thus sinusoidal. In comparison thereto, the speed 15 in the percussion mode S 2 is constant and ideally has the value IS, which can be predefined, for example, via the user interface 11.The local operating current maximum P J is to be understood to mean operating current values which occur periodically with the rotation of the drive motor 2 and which, however, can be subject to fluctuations in their amplitude. Such an operating current maximum P J can also be referred to as an operating current peak P J. An operation current peak P J represents a rotational shock in the striking operation. A time interval of the operating current peaks P J is given by the predefinable impact frequency.Each operating current maximum P J can be assigned a speed IS J wherein j=0, 1, 2, 3,..., n and the IS J assume ideally the same value, but can actually be subject to fluctuations. The speeds IS J can be considered to be identical and the speed IS can thus be considered to be constant if the speeds IS J assigned to the operating current maxima P J assume values within a predeterminable speed interval [IS LOW, IS HI]. In the context of the further method step, speed values IS J are therefore determined at the time of operating current maxima P j of the drive motor 2 and are compared with the predefinable speed IS.The impact operation S 2 is ended at a time t 4 following the time t 2. A time t 3 lying between the times t 2 and t 4 defines a predefinable time duration t 4- t 3, within which the percussion mode S 2 is continued, in order to bring about a predefinable tightening torque, for example. The time t 3 is given by way of example in that three successive operating current maxima P 1, P 2, P 3 occur for which the speeds IS 1, IS 2, IS 3 of the drive motor 2 each assume the value IS of the predeterminable speed. In this case, a consistent impact operation S 2 can be assumed. The percussion mode S 2 is then continued for the predeterminable time duration t 4- t 3 at the predeterminable percussion frequency.If the speed values IS J do not correspond to the predefinable speed, it is possible to check whether a lead time t 0 of the electric hand-held power tool 1 has elapsed before the time t 2. Zone S 1 comprises the lead time t 0 of the electric hand-held power tool 1, within which the drive motor 2 is started up, wherein the operating current 14 and the speed 15 of the drive motor 2 increase over time until a local maximum is reached at the time t 0 in each case. From the time t 0 to a subsequent time t 1, which precedes the time t 2 the speed 15 remains constant and maximum, while the operating current 14 initially decreases, subsequently remains substantially constant and then exceeds the predefinable first threshold value I T. Between the time t 1 and the time t 2 the speed 15 falls to the predeterminable value IS.If lead time t 0 has not elapsed, it is possible to check whether a gradient S of operating current 14 within lead time t 0 is greater than a predefinable second threshold value. By way of example, FIG. 2 shows that the gradient S can be determined on the basis of the initially maximum operating current I max present at the time t 0 by determining a gradient of a straight line which connects the origin to I max. The slope S can, however, also be determined differently. The operation of the electric hand-held power tool 1 can be terminated prematurely if the gradient S of the operating current 14 is greater than the second threshold value, since this is interpreted as a repeated tightening of an already tightened screw connection.The drive motor 2 is controlled within the scope of the method by the controller 7 on the basis of sensor signals of the current sensor 9 and of the speed sensor 10. In addition, the controller 7 is designed to check whether successive speed values IS J of the drive motor 2 correspond to the predeterminable speed ISwhen the electric hand-held power tool 1 is operated in the percussion mode S 2, and to continue the percussion mode S 2 for the predeterminable time duration t 4- t 3 and at the predeterminable percussion frequency if the successive speed values IS J correspond to the predeterminable speed IS.The controller 7 thus comprises an algorithm which can also be referred to as a computer program product. The algorithm comprises instructions which, when executed by the controller 7, cause the controller to perform the method. The algorithm is stored on a memory of the controller 7 or on an external memory.FIG. 3 schematically shows a further exemplary operating current profile 14 and a further associated speed profile 15 of the drive motor 2 of the electric hand-held power tool 1 within the scope of the method for operating the electric hand-held power tool 1. The diagrams of FIGS. 2 and 3 have similarities. Differences will be substantially explained below. Merely by way of example, the time t S in contrast to FIG. 2, corresponds to the time t 1. Reference numerals used so far are retained for similar and identical elements.In the method according to FIG. 3, in the context of a further method step, a further phase Z 2 of the percussion mode S 2 is initiated by the controller 7 after the predeterminable time duration t 4- t 3 has elapsed. The percussion mode S 2 therefore has two percussion phases Z 1, Z 2. A first beat phase Z 1 comprises the time range between t S and t 4. A second beat phase Z 2 comprises a time range between t 4 and a subsequent time t 6. Within the second phase Z 2 of the percussion operation S 2, the electric hand-held power tool 1 is operated for a predeterminable further time duration t 6- t 5 and at a predeterminable further percussion frequency. The fact that the predeterminable further time duration is given by t 6- t 5 and not by t 6- t 4 results from the fact that a time duration t 5- t 4 is required for switching the drive motor 2 from the first percussion phase Z1 to the second percussion phase Z2. In the second percussion phase Z 2, the drive motor 2 is driven in such a way that additional speed values IS J correspond to the predeterminable further speed IS 0 which is, for example, greater than the predeterminable speed IS of the first phase Z 1. FIG. 3 shows, by way of example, a tolerance interval [I LOW, I HI]. only for the predeterminable speed IS. The predefinable speeds IS, IS, 0 can also be referred to as pulse speeds. The additional speed values IS J are determined for the additional operating current maxima P J of the drive motor 2 and are compared with the predefinable further speed IS 0.In comparison with FIG. 2, FIG. 3 thus shows a dual impact mode S 2, which can be used in particular for hard connections in order to achieve a high tightening torque. The predefinable speed IS, the predefinable first time duration t 4- t 3 and the predefinable impact frequency can be predefined, for example, as a function of a degree of hardness of components to be connected by means of the electric hand-held power tool 1. This also applies to the predeterminable further speed IS 0, the predeterminable second time duration t 6- t 5 and the predeterminable further impact frequency.FIG. 4 schematically shows different speeds 15 of the drive motor 2 as a function of time, which can be used for different applications. By way of example, FIG. 4 shows three scenarios with different speeds 15 in the percussion mode S 2, wherein, by way of example, no dual percussion mode S 2 is present, i.e. that in the percussion mode S 2 in each case only a predefined speed IS A, IS B, IS C is used, wherein IS A< IS B< IS C. These pulse speeds IS A, IS B, IS C can be used, for example, in percussion operation S 2 for soft, intermediate and hard connections or screw connections.FIG. 5 schematically shows different speeds 15 of the drive motor 2 as a function of a battery voltage 16. The battery voltage 16 has a minimum V MIN and a maximum V MAX. In general, the battery voltage 16 can be referred to as the supply voltage 16 if the electric hand-held power tool 1 has a different supply source 8 instead of a battery 8.The pulse speeds IS A and IS B correspond, for example, to less than 80% of the maximum speed. The pulse speed IS C has, on the other hand, a value which, for example, is greater than 80% of the maximum speed of the drive motor 2. below a critical battery voltage V 1 the speed IS C cannot be maintained, so that the speed 15 of the drive motor increases linearly from approximately 70% to IS C for example for battery voltages in the range between V MIN and V 1. This can be realized, for example, by pulse-width-modulated actuation of the drive motor 2. The course of the speed 15 in the range between V MIN and V 1 can also be configured differently from that shown in FIG. 5.The predefinable speed IS can therefore be predefined as a function of the battery voltage 16. In this case, the predeterminable speed IScan be selected, for example, up to a critical battery voltage V 1 as a function of the battery voltage 16. Starting from the critical battery voltage V 1, the speed IS can be predefined independently of the battery voltage 16. This is particularly expedient for high speeds IS.FIG. 6 schematically shows a flow diagram of an exemplary method 101 for operating the electric hand-held power tool 1.At the beginning 101 of the method 100, a user can specify a speed IS, a time duration and a percussion frequency for the percussion operation S 2 within the scope of a step 102. In this case, a further speed IS 0, a further time duration and a further impact frequency can also be predefined if a dual impact operation S 2 is to be carried out. The selection of the speed IS can be set at the user interface 11. The selection of the mentioned parameters can be carried out, for example, on the basis of a required tightening torque, for example on the basis of a degree of hardness of a connection to be produced. This selection can also be made from a third device via a wireless connection such as Wi-Fi or Bluetooth. The second step 102 may also be omitted if a setting is maintained.In a second step 102, the activation switch 12 of the electric hand-held power tool is actuated. In a fourth step 104, information on results of operations already performed by means of the electric hand-held power tool 1 stored in a memory of the electric hand-held power tool 1 can be deleted. The fourth step 104 can also be omitted. In a fifth step 105, the supply or battery voltage Dc is read out and, in an optional sixth step 106, is modulated, for example by means of PWM, in order to generate a desired input signal for the drive motor 2. In a seventh step 107, the drive motor 2 is driven on the basis of the input signal from the controller 7. For example, the input signal can be generated as a function of the supply or battery voltage, wherein parameters based on the supply or battery voltage are selected within the scope of pulse width modulation in order to achieve the predefinable speed ISand thus a required tightening torque.Optionally, it can now be checked whether a torque is again exerted on an already established connection. This can damage already established connections. In order to avoid this, it can be checked in an eighth step 108 whether the lead time t 0 has elapsed. If this is not the case, in a ninth step 109, the operating current 14 of the drive motor 2 is read out by means of the current sensor 9. In a tenth step 110, a maximum value of the operating current 14 within the lead time t 0 can be stored on the memory of the electric hand-held power tool 1. In this case, it can be checked again in an eleventh step 111 whether the lead time t 0 has elapsed. If this is the case, in a twelfth step 112 the slope S is determined on the basis of the operating current, for example on the basis of the maximum operating current 14 within the lead time t 0. In a thirteenth step 113, it is checked whether the ascertained gradient S is greater than the predefinable second threshold value. If this is the case, the drive motor 2 is switched off in a fourteenth step 114, i.e. the operation is ended prematurely, since this is interpreted as a new attempt to exert a torque on an already tightened connection. In a fifteenth step 115, information NG1 about the fact that the operation has been terminated prematurely because a re-tightening has been detected can be stored in the memory. Alternatively, after the eleventh step 111, the eighth step 108 can be carried out again if it is found in the context of the check of the eleventh step 111 that the lead time t 0 has not yet elapsed, wherein this check in the eighth step 108 is carried out again until the lead time t 0 has elapsed, or the drive motor 2 is shut off prematurely in the fourteenth step 114.If the lead time t 0 has elapsed and no slope S has been determined which exceeds the second threshold value, then in a sixteenth step the operating current 14 is read out and in a seventeenth step 117 is compared with the predefinable first threshold value I T in order to determine whether the electric hand-held power tool 1 is operated in the percussion mode S 2. If this is not the case, it can be checked in an eighteenth step 118 whether the user is still operating the activation switch 12. If this is the case, the sixteenth and seventeenth steps 116, 117 are repeated. If the user no longer operates the activation switch 12, the drive motor 2 is switched off prematurely in a nineteenth step 119. In a twentieth step 115, information NG 3 about the fact that the operation has been terminated prematurely because the user no longer actuates the activation switch 12 can be stored in the memory.If the operating current 14 is greater than the predefinable first threshold value I T, it can be checked in a twenty-first step 121 whether the operating current 14 has a first operating current peak P J. If this is the case, the associated speed IS J can be read out and stored on the memory in a twenty-second step 122. The speed IS J is therefore determined for the point in time at which the operating current 14 has the operating current peak P J. If the operating current 14 does not have an operating current peak P J the eighth step 108 is carried out, i.e. it is checked whether the lead time t 0 has elapsed in order to be able to exclude premature tightening.In a twenty-third step 123, it is checked whether successive speed values IS J for a corresponding number of operating current peaks P J each correspond to the predeterminable speed IS. If this is the case, the percussion mode S 2 is continued for the predeterminable period of time. For this purpose, a timer can be activated in a twenty-fourth step 124 and it can be checked in a twenty-fifth step 125 whether the predeterminable time duration has been exceeded. If the predeterminable period of time has been exceeded, the drive motor 2 is switched off in a twenty-sixth step 126. In this case, the operation is ended because a desired tightening torque has been reached. In a twenty-seventh step 127, information OK about the fact that the operation has been ended because a work target has been reached can be stored in the memory.If it is found within the scope of the twenty-fifth step 125 that the predeterminable time duration has not yet been exceeded, then in a twenty-eighth step 128 the speed of the drive motor 2 can be read out in order to check in a twenty-ninth step 129 whether further speed values IS J correspond to the predeterminable speed IS. If this is not the case, the drive motor 2 is switched off prematurely in a thirtieth step 130. In a thirty-first step 131, information NG2 about the fact that the operation has been ended, because the further speed values IS J do not correspond to the predeterminable speed IS, can be stored in the memory. If, on the other hand, the further speeds IS J correspond to the predeterminable speed IS, then the twenty-fifth step 125 is repeated until either the predeterminable time duration has elapsed or the further speed values IS J do not correspond to the predeterminable speed IS and the drive motor 2 is switched off.Alternatively, after the twenty-fourth step 124, in a thirty-second step 132, the first phase Z 1 of the percussion operation S 2 can be initiated by the speed IS being predefined. In a thirty-third step 133, a check is then made as to whether the predeterminable time duration has been exceeded. If this is the case, the second phase Z 2 of the percussion mode Z 2 is initiated in a thirty-fourth step 134 by selecting the further predefinable speed IS 0. These speeds can alternatively also be selected in the second step 102, so that a selection within the scope of the thirty-second step 132 and the thirty-fourth step 134 can be omitted, and the phases Z 1, Z 2 are initiated by the controller 7. In a thirty-fifth step 135, a timer is activated and in a thirty-sixth step 136, a check is made as to whether the further predefinable time duration has been exceeded. If this is the case, the drive motor 2 is switched off according to the twenty-sixth step 126. According to the twenty-seventh step 127, information OK that the operation has been ended because a work target has been reached can be stored in the memory. In the dual percussion mode S 2, the speed of the drive motor 2 can also be monitored according to the twenty-eighth and twenty-ninth steps 128, 129 as long as the predeterminable time duration or the further predeterminable time duration has not elapsed in order to possibly shut down the drive motor 2 if the speed, more precisely the further speed values IS J should not coincide with the predeterminable speed IS or the further speed IS 0. In a thirty-seventh step 137, the method 100 can be ended after the drive motor 2 has been switched off in the fifteenth, twentieth, twenty-seventh or thirty-first step 115, 120, 127, 131.Depending on the scenario, the information OK; NG1, NG2, NG3 can be displayed directly to the user. If the predeterminable period of time is exceeded, it is assumed that a required tightening torque has been reached. This is therefore interpreted as a successful completion of a work and can be displayed, for example, by means of a light-emitting diode of the electric hand-held power tool 1, which is designed, for example, to emit green light permanently, which represents the information OK and gives the user a confirmation that a goal has been reached. If the operation was ended prematurely, this can be indicated, for example, by a further light-emitting diode which is designed to emit red light. For example, the further light emitting diode can be designed to emit red light permanently if at least one speed value IS J does not correspond to the predeterminable speed IS or IS 0 or if it has been determined that repeated tightening has taken place and operation has been terminated prematurely. The continuous illumination of the further light-emitting diode thus represents the information items NG 1 and NG 2. The further light emitting diode can also be configured to emit red light in pulsed fashion, whereby the information NG 3 is represented and displayed.Since the information OK; NG1, NG2, NG3 can be stored in the memory, statistics can be created from which a quality of work performed with the electric hand-held power tool 1 arises. FIG. 7 schematically shows exemplary statistics regarding the quality of results achieved by means of the electric hand-held power tool. In this case, a frequency N of the scenarios which are represented by the information OK; NG1, NG2, NG3 stored in the memory is plotted in a bar diagram. This allows a user to analyze and optionally optimize working processes. The information and statistics can be transmitted to external devices via an interface of the electric hand-held power tool 1, for example via an I / O port, or a wireless connection such as Wi-Fi or Bluetooth.

Claims

Method (100) for operating an electric hand-held power tool (1), in particular a rotary impact screwdriver (1), having the following method steps: - checking whether the electric hand-held power tool (1) is operated in an impact operation (S2), wherein an operating current (14) of a drive motor (2) of the electric hand-held power tool (1) is compared with a predefinable first threshold value (I T) wherein the electric hand-held power tool (1) is operated in the impact operation (S2) if the operating current (14) is greater than the predefinable first threshold value (I T), - checking whether successive speed values (IS J) of the drive motor (2) correspond to a predefinable speed (IS) if the electric hand-held power tool (1) is operated in the impact operation (S2), wherein speed values (IS J) for operating current maxima (P J) of the drive motor (2) are determined and compared with the predeterminable speed (IS), - continuation of the percussion operation (S2) for a predeterminable period of time and with a predeterminable percussion frequency if the successive speed values (IS J) correspond to the predeterminable speed (IS).Method (100) according to Claim 1, wherein it is checked whether further speed values (IS J) correspond to the predeterminable speed (IS) as long as the percussion operation (S2) is continued, wherein the operation of the electric hand-held power tool (1) is terminated prematurely if the further speed values (IS J) do not correspond to the predeterminable speed (IS) or wherein the percussion operation (S2) is continued until the predeterminable time duration is exceeded if the further speed values (IS J) correspond to the predeterminable speed (IS).Method (100) according to Claim 1 or 2, wherein before the checking of the speed value values (IS J) it is checked whether the operating current (14) in the percussion mode (S2) has a first operating current maximum (P 1) wherein if the operating current (14) in the percussion mode (S2) has no first operating current maximum (P 1) it is checked whether a lead time (t 0) of the electric hand-held power tool (1) has elapsed.Method (100) according to Claim 1 or 2, wherein, if the speed values (IS J) do not correspond to the predeterminable speed (IS), a check is made as to whether a lead time (t 0) of the electric hand-held power tool (1) has elapsed.Method according to Claim 3 or 4, wherein it is checked whether a gradient (S) of the operating current (14) within the lead time (t 0) is greater than a predefinable second threshold value if the lead time (t 0) has not elapsed, wherein the operation of the electric hand-held power tool (1) is terminated prematurely if the gradient (S) of the operating current (14) is greater than the second threshold value.Method (100) according to one of the preceding claims, wherein it is checked whether a user of the electric hand-held power tool (1) actuates an activation switch (12) of the electric hand-held power tool (1) if the operating current (14) is less than the predeterminable first threshold value (I T), wherein the operation of the electric hand-held power tool (1) is ended prematurely if the user no longer actuates the activation switch (12), wherein it is checked again whether the operating current (14) is greater than the predeterminable first threshold value (I T), if the user actuates the activation switch (12).Method (100) according to one of Claims 2, 5 and 6, having the following further method steps: - indicating that the predeterminable time duration has been exceeded or that the operation of the electric hand-held power tool (1) has been ended prematurely.Method (100) according to claim one of the preceding claims, having the following further method step: - Initiating a further phase (Z2) of the percussion operation (S2) after the elapse of the predeterminable period of time, wherein the electric hand-held power tool (1) is operated within the further phase (Z2) of the percussion operation (S2) for a predeterminable further period of time and at a predeterminable further percussion frequency in such a way that additional speed values (IS J) correspond to a predeterminable further speed IS 0 wherein the additional speed values (IS J) for additional operating current maxima (P J) of the drive motor (2) are determined and compared with the predeterminable further speed (IS 0).Method (100) according to Claim 8, wherein the predeterminable further speed (IS 0) is greater than the predeterminable speed (IS).Method (100) according to one of the preceding claims, wherein the predeterminable speed (IS), the predeterminable first time duration and the predeterminable impact frequency are predetermined as a function of a degree of hardness of components to be connected by means of the electric hand-held power tool (1).Method (100) according to one of the preceding claims, wherein the predeterminable speed (IS) is predetermined as a function of a battery voltage (16) of a battery (8) of the electric hand-held power tool.Method (100) according to one of the preceding claims, wherein the drive motor (2) is actuated in a pulse width modulated manner.A computer program product comprising instructions which, when executed by a processor, cause the processor to perform a method (100) according to any preceding claim.A machine readable storage medium, wherein the computer program product of claim 13 is stored on the machine readable storage product.Electric hand-held power tool (1) having a drive motor (2) for driving a tool holder (3), a current sensor (9) for detecting an operating current (14) of the drive motor (2), a speed sensor (10) for detecting a speed (15) of the drive motor (2) and a controller (7) for actuating the drive motor (2) and for receiving and evaluating sensor signals of the current sensor (9) and of the speed sensor (10), wherein the controller (7) is designed to check whether the electric hand-held power tool (1) is operated in a percussion operation (S2), wherein an operating current (14) of the drive motor (2) of the electric hand-held power tool (1) is compared with a predefinable first threshold value (I T) wherein the electric hand-held power tool (1) is operated in the percussion operation (S2), if the operating current (14) is greater than the first threshold value (I T), and whether successive speed values (IS J) of the drive motor (2) correspond to a predeterminable speed (IS) when the electric hand-held power tool (1) is operated in the percussion mode (S2), and to continue the percussion mode (S2) for a predeterminable period of time and at a predeterminable percussion frequency if the successive speed values (IS J) correspond to the predeterminable speed (IS).

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