IMPACT TOOL AND POWER TOOL

Abstract

An impact tool capable of stopping or decelerating a motor even if seating has occurred before impacting begins is disclosed. A power tool 1, which is an impact tool, includes: a motor 20; an impact mechanism driven by the motor 20; a current measuring device for measuring a motor current; a speed measuring device for detecting a motor speed; and a control unit 40 for controlling the motor. The control unit 40 includes a seating determination mode configured to determine whether a screw is seated in accordance with the measured motor current and motor speed at any time before or after the impact mechanism begins to strike in a screw tightening operation with a plurality of different working conditions, and to stop or decelerate the motor after the screw is determined to be seated.

Description

TECHNICAL FIELD

[0001] The present invention relates to an impact tool and a power tool. STATE OF THE ART

[0002] Patent Document 1 discloses that the seat determination is based on an electric current.

[0003] Patent Document 1: Japanese Patent JP 6 984 742 SUMMARYTechnical problem

[0004] In the technology of Patent Document 1, the motor cannot be stopped or decelerated if the seat is detected before the impact begins by a striking mechanism. Since the seat is determined based on the electric current, there is a risk of over- or under-voltage, resulting in poor performance.

[0005] The present invention aims to solve at least one of the following problems 1 to 3: Problem 1: To provide an impact tool capable of stopping or decelerating a motor even if the seat has been engaged before the impact operation begins. Problem 2: To provide a power tool with good workability. Problem 3: To provide a power tool that can be controlled depending on the machining size. Solution to the problem

[0006] One embodiment of the present invention is an impact tool. The impact tool includes a motor, an impact mechanism driven by the motor, a current measuring device for measuring the current of the motor, a speed measuring device for detecting the speed of the motor, and a control unit for controlling the motor. The control unit includes a seating determination mode configured to determine whether a screw is seated in accordance with the measured current of the motor and the speed of the motor at any time before or after the impact mechanism starts striking in a screw tightening operation with a plurality of different working conditions, and to stop or decelerate the motor after determining that the screw is seated.

[0007] Another embodiment of the present invention is a power tool. The power tool includes a motor and a control unit for controlling the motor. The control unit includes a screw tightening depth control mode configured to estimate a screw tightening depth into a mating material according to a measured state variable of the power tool and control the motor according to the estimated screw tightening depth and a setting value set by a setting unit. The unit is configured to be capable of setting multiple screw tightening depths, including a first screw tightening depth before the screw seats on a mating material and a second screw tightening depth different from the first screw tightening depth, as setting values.

[0008] Another embodiment of the present invention is a power tool. The power tool includes a motor, a current measuring device for measuring the motor current, a speed measuring device for detecting the motor speed, and a control unit for controlling the motor. The control unit includes a machining quantity estimation mode configured to estimate a machining quantity, which is an amount of irreversible machining of a counter material, according to the measured motor current and motor speed, and to control the motor according to the estimated machining quantity. Effect

[0009] The present invention can solve at least one of the above-mentioned problems 1 to 3. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a right side view of a power tool according to a first embodiment of the present invention; Fig. 2 is a right side cross-sectional view of the power tool; Fig. 3 is a block diagram of the power tool; Fig. 4 is a functional block diagram of the control unit of Fig. 3; Fig. 5 is a control flowchart of the control unit in a stopped state; Fig. 6 is a flowchart of the control of the unit in an operating state; Fig. Figures 7(A) - 7(F) are schematic cross-sectional views showing the progress of a screwing operation on a mating material. (G) is a graph showing the temporal changes of the motor current, the motor speed, and the floating amount of the screw head during the Fig. 7(A) to 7(F) shows the screw tightening; Fig. 8 is a graph showing the correlation between the current and speed of the motor in the power tool and the floating amount of the screw head; Fig. 9 is a conceptual diagram showing the structure of a neural network that estimates the floating amount of the screw head in the power tool; Fig. 10 is a diagram similar to Fig. 7(G), which shows that the time series data of the current and speed of the motor from time tn to time t are used as input to estimate the floating amount of the screw head at time t; Fig. 11 is a diagram in which the estimated values ​​of the floating amount of the screw head are compared to the diagram of Fig. 10 are added; Fig. 12 is a functional block diagram of a control unit of a power tool according to a second embodiment of the present invention; Fig. 13 is a flowchart of the control of the unit in the operating state; Fig. 14 is a flowchart for calculating the machining amount in the control unit; Fig. 15 is a conceptual diagram showing an example of a table used to estimate the machining size before starting to strike; Fig. 16 is a conceptual diagram showing an example of a table used to estimate the machining amount after the start of impact; Fig. 17 is a graph showing the relationship between the product of current and speed of the motor and the floating amount of the screw head for two types of screws, and Fig. 18 is a graph showing the average curve of the data for the two types of screws in Fig. 17 shows. DESCRIPTION OF THE EMBODIMENTS (First Embodiment)

[0010] Fig. 1 to 11 refer to a power tool 1 according to a first embodiment of the present invention. The power tool 1 is a working tool, more specifically an impact tool (impact wrench). As shown in Fig. 1 and Fig. As shown in Figure 2, a front-to-back direction and an up-to-down direction of the power tool 1 are defined as perpendicular to each other. The front-to-back direction is a direction parallel to a motor shaft 21.

[0011] As in Fig. 1 and Fig. As shown in Figure 2, the power tool 1 includes a housing 10. The housing 10 is, for example, a resin molded body with a two-part structure consisting of a left section and a right section. The housing 10 includes a motor mounting unit 11, a handle unit 12, and a battery mounting unit 13.

[0012] The motor mounting unit 11 is a cylindrical unit whose central axis runs substantially parallel to the front-to-rear direction. The handle unit 12 has an upper end connected to a center unit of the motor mounting unit 11 in the front-to-rear direction and extending downward from the center unit. The battery mounting unit 13 is provided at a lower end of the handle unit 12, and a battery pack 17 can be detachably attached thereto. The power tool 1 is powered by power from the battery pack 17.

[0013] The power tool 1 includes a rear cover 14 that is connected to an opening on the rear side of the motor mount unit 11 and covers the opening. The rear cover 14 is attached to the motor mount unit 11 by screws or the like.

[0014] The power tool 1 includes a hammer housing 18 connected to the front unit of the motor support unit 11. The hammer housing 18 is made of metal, for example, and is held in the motor support unit 11 and extends forward from the motor support unit 11.

[0015] The power tool 1 has a trigger switch 15 at the upper end of the handle unit 12, which allows the user to switch between driving and stopping a motor 20. The power tool 1 includes a forward / reverse switch 16 near the boundary between the motor receiving unit 11 and the handle unit 12, which allows the user to switch between forward and reverse rotation of the motor 20.

[0016] The power tool 1 includes a first control panel 35 in the battery mounting unit 13. The first control panel 35 is connected to a control unit 40 ( Fig. 3) such as a microcomputer that controls the drive of the motor 20. The power tool 1 includes a control panel 19 on the front top of the battery mounting unit 13. The control panel 19 includes a display unit 46, a control mode switch 47 and a threshold setting device (setting unit) 48, which in Fig. 3 is shown.

[0017] The working machine 1 includes the motor 20, a reduction mechanism 28, a spindle 29, a rotary impact mechanism 30 as an impact mechanism and a fan 34 on the inside of the motor mounting unit 11 and the hammer housing 18.

[0018] The motor 20 is a brushless motor with an inner rotor and includes a motor shaft 21 that runs parallel to the front-to-rear direction. The motor 20 includes a rotor 22, a stator core 23, a stator coil 24, a front insulator 25, and a rear insulator 26.

[0019] The rotor 22 is arranged around the motor shaft 21 and rotates integrally with the motor shaft 21. The stator core 23, the stator coil 24, the front insulator 25, and the rear insulator 26 form a stator of the power tool 1.

[0020] The stator core 23 is arranged radially outside the rotor 22. The stator coil 24 is arranged on the stator core 23. The front insulator 25 is mounted in front of the stator core 23. The rear insulator 26 is mounted on the rear side of the stator core 23. The front insulator 25 and the rear insulator 26 are, for example, molded synthetic resin bodies and provide insulation between the stator core 23 and the stator coil 24.

[0021] A second control panel 36 is mounted on the front of the front insulator 25. The second control panel 36 is provided with a magnetic sensor 50 ( Fig. 3), such as a Hall IC, for detecting the rotational position of the motor 20 and a converter circuit 38 ( Fig. 3) to supply the stator coil 24 with a drive current.

[0022] The reduction mechanism 28 reduces the rotation of the motor 20 and transmits the rotation to the spindle 29. The spindle 29 drives the rotary impact mechanism 30. The rotary impact mechanism 30 is a unit of the power tool 1 and is driven by the motor 20.

[0023] The rotary impact mechanism 30 includes a spring 31, a hammer 32, and an anvil 33. The anvil 33 holds a tool tip, e.g., a bit (not shown). The hammer 32 is in cam engagement with the spindle 29 and is biased forward by the spring 31. The hammer 32, driven by the spindle 29, rotates and strikes the anvil 33. The structure and operation of the rotary impact mechanism 30 are well known and therefore will not be described in detail.

[0024] The fan 34 is attached to the motor shaft 21 behind the rotor 22, rotates together with the motor shaft 21 and generates cooling air for cooling the motor 20 and the like.

[0025] Fig. 3 is a block diagram of the power tool 1. The power tool 1 includes the power supply voltage detection circuit 38, a resistor 39, the control unit 40, a current detection circuit 41, a battery voltage detection circuit 42, a power supply control circuit 43, a drive signal output circuit 44, a rotor position detection circuit 45, the display unit 46, the control mode switch 47, the threshold setting device 48, a drive signal output circuit 49, and the magnetic sensor 50.

[0026] The converter circuit 38 includes six switching elements Q1 to Q6, such as FETs, connected in a three-phase bridge. Resistor 39 is provided in the path of a current flowing through the motor 20 (hereinafter referred to as "motor current").

[0027] The control unit 40 is, for example, a microcomputer (microcontroller) and controls the overall operation of the power tool 1. The current detection circuit 41 detects the motor current from the voltage of the resistor 39 and transmits the motor current to the control unit 40. The current detection circuit 41 and the resistor 39 constitute a current measuring device.

[0028] The battery voltage detection circuit 42 detects the output voltage (hereinafter referred to as "battery voltage") of the battery pack 17 and transmits the battery voltage to the control unit 40. The power supply control circuit 43 converts the battery voltage into a power voltage for the control unit 40 and the like and supplies the power voltage to the control unit 40 and the like. The power supply voltage control detection circuit 44 detects an output voltage of the power supply control circuit 43 and transmits the output voltage to the control unit 40.

[0029] The rotor position detection circuit 45 detects a rotation position (rotor rotational position) of the motor 20 based on an output signal of the magnetic sensor 50 and transmits the rotational position to the control unit 40. The control unit 40 detects the rotational speed (hereinafter referred to as "motor rotational speed") of the motor 20 based on the output signal of the rotor position detection circuit 45. The rotor position detection circuit 45, the magnetic sensor 50, and the control unit 40 constitute a rotational speed measuring means.

[0030] The display unit 46 displays the current threshold values ​​(setting values) and the control mode. The control mode switch 47 is, for example, a push button switch and is a unit with which the user switches between enabling and disabling a machining amount control mode to be described later. The threshold setting unit 48 is a device (unit) that sets a threshold value (setting value) in the machining amount control mode described later. The threshold setting device 48 is, for example, a switch (push button) provided on the control panel 19. Alternatively, the threshold setting device 48 may be a rotary knob provided separately from the control panel 19 or a wireless communication device that receives the threshold value via wireless communication with an external device such as a smartphone.

[0031] The drive signal output circuit 49, under the control of the control unit 40, applies a drive signal, e.g., a PWM signal, to each of the gates of the switching elements Q1 to Q6 of the converter circuit 38. The magnetic sensor 50 outputs a signal corresponding to the rotational position of the motor 20 to the rotor position detection circuit 45.

[0032] The control unit 40 controls the on / off of the switching elements Q1 to Q6 via the drive signal output circuit 49 depending on the operation of the trigger switch 15, the state of the forward / reverse switch 16, whether the machining amount control mode is enabled or disabled, and the threshold value in the machining amount control mode, thereby controlling the drive of the motor 20.

[0033] Fig. 4 is a functional block diagram of the control unit 40 of Fig. 3. Anyone who Fig. The blocks shown in Figure 4 represent a function of the control unit 40, but this does not mean that each of the blocks has actual hardware. Furthermore, "NN" in the drawings stands for a neural network.

[0034] The control unit 40 includes a rotation speed calculation unit 51, a data storage unit 52, a trained model 53, a motor power setting unit 54, an output stability determination unit 55, a neural network calculation unit 56 (hereinafter referred to as “NN calculation unit 56”), a threshold calculation unit 57, a comparator 58, a control mode setting unit 59, an AND gate 60, and a motor control unit 61.

[0035] The rotation speed calculation unit 51 calculates the motor speed based on a received signal from the rotor position detection circuit 45. In the drawing, “rotation speed” refers to the number of revolutions of the motor 20 per unit time (hereinafter “motor rotation speed”), that is, the motor speed.

[0036] The data storage unit 52 stores the motor speed calculated by the rotational speed calculation unit 51 and the motor current received from the current detection circuit 41, that is, the measured values ​​of the motor speed and the motor current.

[0037] The trained model 53 is a functional block that stores neural network parameters (hereinafter referred to as "NN parameters") for estimating the machining quantity, such as screw tightening depth, from time series data of motor speed and motor current. The NN parameters include weights and biases. The NN parameters are generated in advance through machine learning. The machine learning process will be described later.

[0038] The motor power setting unit 54 detects the turning on of the trigger switch 15 and transmits the turning on to the output stability determination unit 55. Furthermore, the motor power setting unit 54 transmits an output setting signal corresponding to the triggering amount of the trigger switch 15 to the motor control unit 61.

[0039] When a predetermined time has elapsed since the trigger switch 15 was turned on, the output stability determination unit 55 determines that the output of the motor 20 has stabilized and changes a neural network calculation enable signal (hereinafter referred to as “NN calculation enable signal”) from a low level (disabled) to a high level (enabled).

[0040] When the NN calculation enable signal is at a high level, the NN calculation unit 56 calculates an estimated value for the machining amount based on the time series data of the motor speed and motor current measurement values ​​stored in the data storage unit 52 and the NN parameters stored in the trained model 53.

[0041] The threshold setting device (unit 57) receives a threshold setting input from the threshold setting device (48) and outputs a threshold value. The comparator 58 compares the estimated value of the machining quantity with the threshold value and outputs a low-level signal when the estimated value of the machining quantity is equal to or less than the threshold value, or outputs a high-level signal when the estimated value of the machining quantity exceeds the threshold value.

[0042] The control mode setting unit 59 detects the operation of the control mode switch 47 and outputs a machining size control mode enable / disable signal. The machining size control mode enable / disable signal is high when the machining size control mode is enabled and low when the machining size control mode is disabled. The display unit 46 indicates whether the machining size control mode is enabled or disabled.

[0043] The AND gate 60 outputs a signal that is the logical AND operation between the machining amount control mode enable / disable signal and the output signal of the comparator 58. In other words, the AND gate 60 outputs the output signal of the comparator 58 to the motor control unit 61 when the machining amount control mode enable / disable signal is at a high level (when the machining amount control mode is enabled).

[0044] The output signal of the AND gate 60 being at a high level means that the machining quantity control mode is enabled and the estimated value of the machining quantity exceeds the threshold, and means that a stop / low speed control request signal is output to the engine control unit 61. The output signal of the AND gate 60 being at a low level means that the machining quantity control mode is disabled and / or the estimated value of the machining quantity is equal to or less than the threshold, and means that the stop / low speed control request signal is not output to the engine control unit 61.

[0045] The motor control unit 61 outputs a motor control signal corresponding to the output setting signal from the motor power setting unit 54 to the drive signal output circuit 49 ( Fig. 3). When the stop / low speed control request signal is input, that is, when the stop / low speed control request signal is at a high level, the engine control unit 61 outputs a motor control signal for performing stop / low speed control of the engine 20 to the drive signal output circuit 49 ( Fig. 3) regardless of the output setting signal from the engine power setting unit 54.

[0046] Stop / low-speed control is a control to stop the motor 20 or a control to slow the motor 20 so that it rotates at a low speed. The control to stop the motor 20 may involve decelerating the motor 20, or it may involve allowing the motor 20 to decelerate naturally without applying the brakes. Thus, the machining amount control mode is a mode in which the motor 20 is stopped / controlled to a low speed when the estimated value of the machining amount exceeds the threshold. The machining amount control mode corresponds to a screw tightening depth control mode and a machining amount estimation mode.

[0047] Fig. Fig. 5 is a control flowchart of the control unit 40 in a stopped state. When the trigger switch 15 is turned on (Yes in S1), the control unit 40 goes to a Fig. 6 for an operating state above (S3). When the trigger switch 15 is off (No in S1), the control unit 40 stops the motor 20 (S5).

[0048] When the control mode switch 47 is turned on (Yes in S7), the control unit 40 sets the machining size control mode enable / disable signal to a high level (enabled) (S9). When the control mode switch 47 is turned off (No in S7), the control unit 40 sets the machining size control mode enable / disable signal to a low level (disabled) (S11).

[0049] The control unit 40 checks the threshold setting input value from the threshold setting device (setting unit) 48 (S13). If the threshold setting input value does not match the current threshold (Yes in S15), the control unit 40 updates the threshold (replaces the threshold setting input value with the threshold) (S17) and returns to S1. If the threshold setting input value matches the current threshold (No in S15), the control unit 40 returns to S1.

[0050] Fig. 6 is a control flowchart of the control unit 40 in an operating state. The control unit 40 acquires the motor current and motor speed as tool state data (S21). When the machining quantity control mode is enabled (Yes in S23) and the NN calculation enable signal is at a high level (Yes in S25), the control unit 40 performs a neural network calculation (hereinafter referred to as "NN calculation") and derives a machining quantity estimate using the trained model 53 (S27).

[0051] If the estimated value of the machining quantity exceeds the threshold (Yes in S29), the control unit 40 performs stop / low-speed control for the motor 20 (S31). If the estimated value of the machining quantity does not exceed the threshold (No in S29), the control unit 40 performs normal control of the motor 20, that is, it controls the rotation speed according to the pulling amount of the trigger switch 15 (S33).

[0052] For a screw tightening tool such as the power tool 1, the machining size is determined by the screw tightening depth (the length the tip of the screw penetrates into the mating material) and a Fig. 7(A) (the distance between the surface of the mating material and the screw head until the top of the screw head is flush with the surface of the mating material). When the machining amount is the screw head floating amount, the smaller the machining amount, the more the machining progresses, so the direction of the inequality sign is reversed in the determination of S29. That is, the control unit 40 performs stop / low-speed control for the motor 20 when the estimated value of the machining amount (estimated value of the screw head floating amount) is less than the threshold value, and performs normal control for the motor 20 when the estimated value of the machining amount (estimated value of the screw head floating amount) is equal to or greater than the threshold value.The estimated value of the screw tightening depth can be calculated by subtracting the current estimated value of the screw head floating amount from the originally derived estimated value of the screw head floating amount.

[0053] For example, if the screw is a wood screw, a hole is drilled into the mating material, so the screw tightening depth and the amount of floating of the screw head are examples of the extent of irreversible machining of the mating material. On the other hand, the mutual fastening of a screw and a nut, for example, is a reversible machining operation because drilling a hole is not required.

[0054] If the machining size control mode is not enabled (No in S23) or if the NN calculation enable signal is at a low level (No in S25), the control unit 40 performs normal control of the motor 20 (S33). If the NN calculation enable signal is at a low level, because the output of the motor 20 is not stable before a predetermined time has elapsed since the trigger switch 15 is turned on, and there is a risk of erroneous determination due to a starting current, etc., the process does not proceed to the NN calculation (S27).

[0055] Fig. 7(A) to 7(F) are schematic cross-sectional views showing the flow of a screwing operation on a mating material. Fig. 7(A) shows the state at the beginning of the screwing process in which a bit 37 of the power tool 1 is engaged with a screw 63 and the screw 63 is inserted into the surface of a plasterboard 64. Fig. 7(B) to 7(E) show the conditions during tightening of the screw. Fig. 7(B) shows the state before the tip of the screw 63 reaches a base 65. Fig. 7(C) shows the state when the tip of the screw 63 reaches the base 65. Fig. 7(D) shows the state where the tip of the screw 63 penetrates through the base 65. Fig. 7(E) shows the seated state in which the lower end of the head of the screw 63 (the lower end of the conical unit) comes into contact with the surface of the plasterboard 64 and begins to cut into the surface. Fig. 7(F) shows a state in which the head of the screw 63 is flush with the surface of the plasterboard 64, that is, the floating amount of the screw head is zero.

[0056] Fig. 7(G) is a graph showing the temporal changes of the motor current, the motor speed and the floating amount of the screw head during the Fig. 7(A) to 7(F). A to F in the diagram indicate time ranges or time periods corresponding to the conditions in Fig. 7(A) to 7(F). As shown in the diagram of Fig. As shown in Figure 7(G), the time series data of the actually measured values ​​of the motor current and motor speed, as well as the floating amount of the screw head obtained from an external distance measuring sensor, are used in machine learning to calculate NN parameters for the Fig. 4. In the design phase of the power tool 1, by performing operations for fastening different types of screws in different types of mating materials and by performing machine learning by the control unit 40 using time series data as shown in the diagram of Fig. 7(G), NN parameters are generated that can handle different types of screws, different types of mating materials, and the application or non-application of impact.

[0057] Fig. Figure 8 is a graph showing the correlation between the current and rotational speed of the motor 20 in the power tool 1 and the floating amount of the screw head. As shown in Fig. As shown in Figure 8, there is a positive correlation between the motor speed and the floating amount of the screw head, while there is a negative correlation between the motor current and the floating amount of the screw head. That is, a correlation was confirmed where the floating amount of the screw head is large when the motor current is small and the motor speed is high, and the floating amount of the screw head is small when the motor current is large and the motor speed is low.

[0058] Fig. Figure 9 is a conceptual diagram showing the structure of a neural network that estimates the floating amount of the screw head in the power tool 1. As shown in Fig. As shown in Figure 8, there is a correlation between the floating amount of the screw head and the motor current and speed. Using this correlation, as shown in Fig. As shown in Figure 9, the floating amount of the screw head can be estimated by a neural network that inputs a predetermined number of samples of time series data on the motor current and the motor speed and outputs the floating amount of the screw head. In the embodiment, the actual floating amount of the screw head is estimated and calculated using the trained model 53, which is developed using a neural network with the Fig. The structure shown in Figure 9 was machine-learned.

[0059] As in Fig. As shown in Figure 10, the floating amount of the screw head at time t is estimated using time series data of the motor current and motor speed from time tn to time t as input. The length of time from time tn to time t and the number of time series data are arbitrarily set according to the specifications of the power tool 1.

[0060] Fig. 11 is a diagram in which estimated values ​​of the floating amount of the screw head are compared to the diagram of Fig. 10. The estimated value of the screw head floating amount was calculated by inputting the actual time series data of the motor current and motor speed into a trained neural network. The estimated value of the screw head floating amount generally follows the actually measured value of the screw head floating amount. When the estimated value of the screw head floating amount falls below the set threshold (the "motor stop threshold" in the figure) (when the estimated value of the screw tightening depth exceeds the set threshold), the screw can be automatically stopped when the screw is seated, the screw can be automatically stopped when the screw head floating amount becomes zero, or the screw can be stopped at a predetermined screw head floating amount (predetermined screw tightening depth), etc.

[0061] This embodiment offers the following functions and effects.

[0062] (1) The control unit 40 can estimate the floating amount of the screw head based on the measured motor current and motor speed at any time before or after the start of impact by the rotary impactor 30 during the screw tightening process under a variety of different working conditions. Therefore, by setting a threshold corresponding to the seating, the motor 20 can be stopped or decelerated even if the screw is seated before the rotary impactor 30 is started by determining whether the screw is seated or not. The machining amount control mode in the case where the threshold corresponds to the seating corresponds to the seating determination mode.

[0063] (2) The control unit 40 determines whether the screw is tight based on the measured motor current and motor speed, so that over-tightening and under-tightening can be prevented compared to determining the tightness based on the motor current alone, which improves the machining quality.

[0064] (3) The control unit 40 is configured to include a learning model (trained model 53) that estimates the screw tightening depth (screw head float) according to the measured motor current and motor speed, and stops or decelerates the motor 20 depending on the estimated screw tightening depth and a set value (threshold). Therefore, the screw tightening depth (screw head float) can be estimated with high accuracy using a neural network.

[0065] (4) The control unit 40 can estimate the screw tightening depth (floating amount of the screw head) before the screw is seated. Accordingly, the threshold setting device 48 is configured to set multiple tightening depths as thresholds (setting values), including a first screw tightening depth (a first floating amount of the screw head) before the screw seats on the mating material and a second screw tightening depth different from the first screw tightening depth. Therefore, the motor 20 can be stopped or decelerated at a stage before seating, which is convenient for manually adjusting the screw tightening depth before and after seating and provides good operability.As a second screw tightening depth, a screw countersink amount (negative floating amount of the screw head) can also be set, at which the screw head sits on the mating material and sinks further into the mating material, which can ideally meet a variety of work requirements. (Second embodiment)

[0066] Fig. 12 to 17 show a power tool according to a second embodiment of the present invention. The power tool is the same as the power tool of the first embodiment except for the method for estimating (calculating) the machining amount.

[0067] Fig. Fig. 12 is a functional block diagram of a control unit 140 of the power tool according to the second embodiment of the present invention. The control unit 140 is configured to process the trained model 53 and the NN calculation unit 56 of the control unit 40 in Fig. 4 can be replaced by a machining size calculation program 62. Furthermore, the NN calculation enable signal in Fig. 4 by a machining size calculation enable signal in Fig. 12, but the function as a signal is the same. The operation of the machining size calculation program 62 will be explained later with reference to Fig. 14 described.

[0068] Fig. 13 is a control flowchart of the control unit 140 during operation. The control flowchart of the control unit 140 in the stopped state is the same as that in Fig. 5. The control unit 140 acquires the motor current and the motor speed as tool status data (S41). When the machining size control mode is enabled (Yes in S43) and the machining size calculation enable signal is at a high level (Yes in S45), the control unit 140 executes the Fig. 14 and derives a machining size calculation value (S47).

[0069] If the calculation value of the machining amount exceeds the threshold (Yes in S49), the control unit 140 performs stop / low-speed control for the motor 20 (S51). If the calculation value of the machining amount does not exceed the threshold (No in S49), the control unit 140 performs normal control of the motor 20, that is, it controls the speed according to the pulling amount of the trigger switch 15 (S53). If the machining amount control mode is not enabled (No in S43) or if the machining amount calculation enable signal is low (No in S45), the control unit 140 performs normal control of the motor 20 (S53).

[0070] Fig. Figure 14 is a flowchart of the machining quantity calculation in control unit 140. If the elapsed time since the machining quantity calculation enable signal reached a high level (since the transition to Yes in S45) does not exceed a predetermined time (No in S61), control unit 140 integrates the motor current x the motor speed (S63). A target power is calculated from the integral value in S65, which will be described later.

[0071] When the elapsed time since the machining size calculation enable signal reached a high level (since the transition to Yes in S45) exceeds the preset time (Yes in S61), the control unit 140 calculates a reference output by dividing the integral value calculated in S63 by the preset time (S65). The reference output is used as a criterion for changing the control depending on the counter material and screw combination, that is, for selecting a table used in S71 or S73, as described later.

[0072] The control unit 140 performs FFT (Fast Fourier Transformation) processing of the motor current measurement data. If the amplitude value of a predetermined frequency in the frequency spectrum obtained by the FFT exceeds a predetermined value (Yes in S69), the control unit 140 determines that a strike is being performed by the rotary impactor 30, and the process proceeds to S71. If the amplitude value of the predetermined frequency in the frequency spectrum obtained by the FFT does not exceed the predetermined value (No in S69), the control unit 140 determines that no strike is being performed, and the process proceeds to S73. The predetermined frequency at this time is determined by multiplying the rotation frequency of the hammer 32 ( Fig. 2), which is calculated from the engine speed, by the number of intermeshing teeth between the hammer 32 and the anvil 33 ( Fig. 2) is divided.

[0073] After performing the impact detection (S69), the control unit 140 derives a calculation value of the screw tightening depth (screw head floatation amount) based on the target output value, the actual value, and the rotational speed from a pre-impact table. In this case, different tables are used depending on whether an impact operation is being performed. That is, if it is determined that the rotary impactor 30 is performing an impact (Yes in S69), the control unit 140 derives a calculation value (estimated value) of the screw tightening depth (screw head floatation amount) from the reference output value, the motor current, and the motor rotational speed based on the pre-impact table (S71).When it is determined that the impact is performed by the rotary impact mechanism 30 (No in S69), the control unit 140 derives a calculation value (estimated value) of the screw tightening depth (floating amount of the screw head) from the reference output, the motor current, and the motor speed based on the post-impact table (S73).

[0074] Fig. Figure 15 is a conceptual diagram showing an example of a table used to estimate the machining size before starting to strike. Fig. Figure 16 is a conceptual diagram showing an example of a table used to estimate the machining amount after the start of impact. As shown in the figures, the table is configured as a three-dimensional table in which an estimated value of the screw head float amount is specified by the reference output, motor current, and motor speed.

[0075] Fig. Figure 17 is a graph showing the relationship between the product of motor current and motor speed and the amount of floating of the screw head for two types of screws. The two types of screws have different lengths, with screw 2 being longer than screw 1. In the graph of Fig. Figure 17 shows the relationship between the product of the measured values ​​of the motor current and the motor speed when the two types of screws are tightened 20 times each and the measured value of the floating amount of the screw head. Fig. 18 is a graph showing the average curve of the data for the two types of screws in Fig. 17 shows.

[0076] In the embodiment, a table for estimating the machining size as shown in Fig. 17, is created and stored in advance based on the previously acquired actual measurement data of the motor current, motor speed, and screw head float. The table is created to create an average curve of the data on the screw head float as a function of the product of motor current and motor speed, as shown in Fig. 18. According to the embodiment, when the type of screw or mating material is different, by utilizing the fact that the output (which is shown in S65 of Fig. 14 calculated reference output) at the beginning of tightening, when the floating amount of the screw head is large, is slightly different, generating a table that can accommodate different types of screws and different types of mating materials. This embodiment also provides the same or equivalent functions and effects as the first embodiment.

[0077] Although the present invention has been described above using the embodiments as examples, those skilled in the art will understand that various modifications can be made to each component and processing process of the embodiments within the scope of the claims. A modified example is described below.

[0078] In the present invention, the extent of irreversible machining is not limited to the screw tightening depth or the floating amount of the screw head, but can also be, for example, the drilling depth. The power tool of the present invention is not limited to an impact tool, but can be any other type of tool capable of screwing or drilling, such as a drill driver or an oil pulse tool. Furthermore, the present invention can be applied to all power tools in which state variables such as the motor current and motor speed and their time series data are related to the machining amount.

[0079] The time, motor current, motor speed, screw head floating amount, reference power, etc. indicated as specific numerical values ​​in the embodiments and drawings do not limit the scope of the invention in any way and may vary depending on the product specifications. List of reference symbols 1 power tool 10 housings 11 Motor mounting unit 12 handle unit 13 Battery mounting unit 14 Rear cover 15 trigger switches 16 Forward / Reverse Switch 17 Battery pack 18 hammer housing 19 Control panel 20 engine 21 Motor shaft 22 Rotor 23 Stator core 24 Stator coil 25 front insulator 26 rear insulator 28 Reduction mechanism 29 spindle 30 rotary impact mechanism 31 spring 32 hammers 33 Anvil 34 blowers 35 first control panel 36 second control panel 37 bits 38 converter circuit 39 Resistance 40 Control unit 41 Current detection circuit 42 Battery voltage detection circuit 43 Power supply control circuit 44 Power supply voltage detection circuit 45 Rotor position detection circuit 46 display unit 47 Control mode calculation circuit 48 Threshold setting device (setting unit) 49 Threshold calculation circuit 50 magnetic sensor 51 Rotor position detection circuit 52 Data storage unit 53 trained models 54 Engine power adjustment unit 55 Output stability determination unit 56 NN calculation unit 57 Threshold setting unit 58 Comparator 59 Control mode setting unit 60 AND gates 61 Engine control unit 62 Machining size calculation program 63 Screw 64 plasterboard 65 base. QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] JP 6 984 742

[0003]

Claims

[1] Impact tool comprising: an engine; a striking mechanism driven by the motor; a current measuring device for measuring a current of the motor; a speed measuring means for detecting a speed of the engine; and a control unit that controls the motor, the control unit including a seating determination mode configured to determine whether a screw is seated in accordance with the current of the motor and the speed of the motor that are measured at any time before or after the impact mechanism starts striking in a screw tightening operation having a variety of different working conditions, and to stop or decelerate the motor after the screw is determined to be seated. [2] The impact tool according to claim 1, wherein, in the seating detection mode, the control unit is configured to determine that the screw is seated when the current of the motor and the rotational speed of the motor reach a first value and a second value, respectively, before the driving is started in the screw tightening operation under a first working condition, and to determine that the screw is seated when the current of the motor and the rotational speed of the motor reach a third value and a fourth value, which are different from the first value and the second value, respectively, after the impact operation is started in the screw tightening operation under a second working condition, which is different from the first working condition. [3] The impact tool according to claim 2, wherein the control unit is configured to include a learning model that estimates a screw tightening depth according to the current of the motor and the speed of the motor that are measured, and stops or decelerates the motor depending on the estimated screw tightening depth and a set target value. [4] Power tool having: an engine; and a control unit that controls the motor, the control unit including a screw tightening depth control mode configured to estimate a screw tightening depth into a mating material according to a measured state variable of the power tool and to control the motor according to the estimated screw tightening depth and a setting value set by a setting unit, wherein the unit is configured to be capable of setting a plurality of screw tightening depths, including a first screw tightening depth before a screw is seated in a mating material and a second screw tightening depth different from the first screw tightening depth, as setting values. [5] The power tool according to claim 4, wherein the screw tightening depth is a screw head floating amount, which is a distance between a screw head and the mating material, or a screw sinking amount, which is a measure of the screw head sitting on the mating material and further sinking into the mating material. [6] The power tool of claim 4, wherein the second screw tightening depth is a screw tightening depth after the screw is seated on the mating material. [7] The power tool according to any one of claims 4 to 6, wherein the control unit is configured to include a learning model that estimates a screw tightening depth into a mating material according to a measured state quantity of the power tool, and stops or decelerates the motor according to the estimated screw tightening depth and a setting value set by a setting unit. [8] Power tool having: an engine; and a current measuring device for measuring a current of the motor; a speed measuring means for detecting a speed of the engine; and a control unit that controls the motor, the control unit including a machining amount estimation mode configured to estimate a machining amount, which is an amount of irreversible machining of a counter material, according to the current of the motor and the rotational speed of the motor that are measured, and control the motor according to the estimated machining amount. [9] The power tool according to claim 8, wherein the machining size is a screw tightening depth or a drilling depth. [10] The power tool according to claim 8 or 9, wherein the control unit is configured to include a learning model configured to estimate a machining amount of a counter material according to the current of the motor and the rotational speed of the motor, which are measured, and to control the motor according to the estimated machining amount and a setting value set by a setting unit.

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