Impact tool, control method and program

Abstract

To improve calculation accuracy of fastening torque.SOLUTION: An impact tool 1 includes a motor 2, a hammer, an anvil, an output shaft, a torsional amount measurement part 5, a torque calculation part 85, an estimation part 83 and a coefficient setting part 84. The torsional amount measurement part 5 measures a torsional amount of the output shaft. The torque calculation part 85 subjects first information included in a measurement result of the torsional amount measurement part 5 to conversion treatment using a conversion coefficient, and calculates fastening torque applied to a fastening member through a tip tool from the output shaft. The estimation part 83 estimates a weight of the tip tool using a mechanically learned model so as to output the weight of the tip tool with second information included in the measurement result of the torsional amount measurement part 5 as an input. The coefficient setting part 84 sets a conversion coefficient according to the weight of the tip tool. The torsional amount measurement part 5 outputs the measurement result as a time change of a voltage value. The voltage value takes a first maximum value in a first period, and takes a second maximum value in a subsequent second period. First information includes at least the second maximum value.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure generally relates to an impact tool, a control method, and a program, and more particularly, to an impact tool including a motor, a control method, and a program. [Background technology]

[0002] Conventionally, an impact fastening tool has been known in which the rotational force of a rotary drive source is converted into intermittent impacts by an impact generating device, and the impact force is applied to a main shaft to fasten a screw member (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2009-83024 A Summary of the Invention [Problem to be solved by the invention]

[0004] In an impact fastening tool (impact tool) such as that described in Patent Document 1, there has been a demand for improvement in the accuracy of calculating the torque (fastening torque) for fastening a screw member.

[0005] The present disclosure has been made in consideration of the above circumstances, and aims to provide an impact tool, a control method, and a program that are capable of improving the calculation accuracy of fastening torque. [Means for solving the problem]

[0006] An impact tool according to one aspect of the present disclosure includes a motor, a hammer, an anvil, an output shaft, a torsion amount measuring unit, a torque calculating unit, an estimating unit, and a coefficient setting unit. The hammer rotates by receiving power from the motor. The anvil rotates by receiving an impact force from the hammer in the rotation direction of the hammer. The output shaft is configured to hold a tool tip that tightens a fastening member, and rotates together with the anvil. The torsion amount measuring unit measures the torsion amount of the output shaft when the hammer applies the impact force to the anvil. The torque calculating unit calculates the tightening torque applied to the fastening member from the output shaft via the tool tip by performing a conversion process using a conversion coefficient on first information included in the measurement result of the torsion amount measuring unit. The estimating unit estimates the weight of the tool tip using a trained model that is machine-learned to output the weight of the tool tip using second information included in the measurement result of the torsion amount measuring unit as an input. The coefficient setting unit sets the conversion coefficient according to the weight of the tool bit estimated by the estimation unit. The torsion amount measuring unit outputs the measurement result as a time change in a voltage value. The voltage value has a first maximum value in a first period and has a second maximum value in a second period following the first period. The first information includes at least the second maximum value.

[0007] A control method according to one aspect of the present disclosure is a control method for an impact tool including a motor, a hammer, an anvil, and an output shaft. The hammer rotates by receiving power from the motor. The anvil rotates by receiving an impact force from the hammer in the rotation direction of the hammer. The output shaft is configured to hold a tool tip that tightens a fastening member, and rotates together with the anvil. The control method includes a twist amount measurement step, a torque calculation step, an estimation step, and a coefficient setting step. In the twist amount measurement step, a twist amount of the output shaft when the hammer applies an impact force to the anvil is measured. In the torque calculation step, a conversion process is performed using a conversion coefficient on first information included in the measurement result in the twist amount measurement step, thereby calculating a tightening torque applied to the fastening member from the output shaft via the tool tip. In the estimation step, the weight of the tool tip is estimated using a trained model that has been machine-learned to output the weight of the tool tip using second information included in the measurement result in the twist amount measurement step as an input. In the coefficient setting step, the conversion coefficient is set according to the weight of the tool bit estimated in the estimation step. In the torsion amount measuring step, the measurement result is output as a time change in a voltage value. The voltage value has a first maximum value in a first period and has a second maximum value in a second period following the first period. The first information includes at least the second maximum value.

[0008] A program according to one embodiment of the present disclosure is a program for causing one or more processors to execute the control method. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide an impact tool, a control method, and a program that are capable of improving the calculation accuracy of the tightening torque. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of an impact tool according to one embodiment of the present disclosure. [Diagram 2] FIG. 2 is a block diagram showing a configuration of the impact tool. [Diagram 3] FIG. 3 is a graph showing raw data of the measurement results of the torsion amount measuring unit provided in the impact tool. [Figure 4] FIG. 4 is a graph showing the measurement results of the torsion amount measuring unit provided in the impact tool. [Diagram 5] FIG. 5 is a graph showing the measurement results of the torsion amount measuring unit provided in the impact tool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The impact tool 1 according to the embodiment of the present disclosure will be described in detail with reference to the drawings. Note that the embodiment and modified examples described below are merely examples of the present disclosure, and the present disclosure is not limited to the embodiment and modified examples. Even if the embodiment and modified examples are not included, various modifications are possible according to the design and the like, as long as they do not deviate from the technical idea of ​​the present disclosure. In addition, each figure described in the following embodiment is a schematic diagram, and the ratio of the size and thickness of each component in the figure does not necessarily reflect the actual dimensional ratio. The arrows indicating each direction in the drawings are merely examples, and are not intended to define the direction of the impact tool 1 when in use. In addition, the arrows indicating each direction in the drawings are merely indicated for the purpose of explanation, and do not have any substance.

[0012] (1) Overview An outline of an impact tool 1 according to the present embodiment will be described with reference to FIGS. 1, 2, 4 and 5. FIG.

[0013] The impact tool 1 is, for example, an impact wrench, an impact driver, a hammer drill, an impact drill, or an impact drill driver. In the following, a case where the impact tool 1 is an impact wrench will be described as an example. In addition, a case where the impact tool 1 is used to perform an operation (fastening operation) of tightening a fastening member B1, for example, a bolt, into a screw hole provided in a fastening member such as wood or a metal member will be described as an example.

[0014] As shown in Figures 1 and 2, the impact tool 1 includes a motor 2, a hammer 33, an anvil 34, an output shaft 4, a torsion amount measuring unit 5, a torque calculation unit 85, an estimation unit 83, and a coefficient setting unit 84.

[0015] The hammer 33 receives power from the motor 2 and rotates.

[0016] The anvil 34 receives an impact force from the hammer 33 in the rotational direction of the hammer 33 and rotates.

[0017] The output shaft 4 is configured to hold an end tool 11 for tightening the fastening member B1, and rotates together with the anvil .

[0018] The torsion amount measuring unit 5 measures the amount of torsion of the output shaft 4 when the hammer 33 applies an impact force to the anvil 34 .

[0019] The torque calculation unit 85 calculates the tightening torque applied to the fastening member B1 from the output shaft 4 via the tool tip 11 by performing a conversion process using a conversion coefficient on the first information contained in the measurement result of the torsion amount measuring unit 5.

[0020] The estimation unit 83 estimates the weight of the tool tip 11 using a trained model that has been machine-learned to input the second information included in the measurement results of the twist amount measuring unit 5 and output the weight of the tool tip 11.

[0021] The coefficient setting unit 84 sets a conversion coefficient in accordance with the weight of the tool bit 11 estimated by the estimation unit 83 .

[0022] The twist amount measuring unit 5 outputs the measurement result as a change in voltage value Vts over time, as shown in FIGS.

[0023] The voltage value Vts has a first maximum value P1 in a first period ΔT1, and has a second maximum value P2 in a second period ΔT2 following the first period ΔT1.

[0024] The first information includes at least the second maximum value P2.

[0025] Here, it is known that in the impact tool 1, even if the rotation speed of the motor 2 is the same, the heavier the tool bit 11 is, the greater the torque required to rotate the tool bit 11 becomes, and the true value of the tightening torque decreases. The true value of the tightening torque is, for example, a value measured by a torque measuring device provided separately from the impact tool 1.

[0026] According to the above-mentioned configuration, the tightening torque can be calculated in consideration of the weight of the tool bit 11, and the calculation accuracy of the tightening torque can be improved.

[0027] (2) Impact tool configuration As shown in Figures 1 and 2, the impact tool 1 includes a motor 2, an impact mechanism 3, an output shaft 4, a torsion measuring unit 5, an operation unit 7, a control unit 8, a memory unit 9, and a communication unit 13.

[0028] As shown in FIG. 1, a rechargeable battery pack 10 is detachably attached to the impact tool 1. The impact tool 1 of this embodiment operates using the battery pack 10 as a power source. The battery pack 10 is a power source that supplies a current to drive the motor 2. The battery pack 10 includes, for example, a battery pack configured by connecting a plurality of secondary batteries (for example, lithium ion batteries) in series, and a case that houses the battery pack. The battery pack 10 is not a component of the impact tool 1. However, the impact tool 1 may include the battery pack 10 as a component.

[0029] The motor 2 is, for example, a brushless motor. The motor 2 includes a rotating shaft 21. The motor 2 converts the electric power supplied from the battery pack 10 into a rotational driving force of the rotating shaft 21.

[0030] The operation unit 7 accepts operations for controlling the rotation of the motor 2. By pulling the operation unit 7, the motor 2 can be switched on and off. In addition, the rotation speed of the motor 2 can be adjusted by the pulling amount of the operation of pulling the operation unit 7. The larger the pulling amount, the faster the rotation speed of the motor 2 becomes.

[0031] The impact mechanism 3 performs an impact operation to generate an intermittent impact force on the output shaft 4 from the power of the motor 2 .

[0032] 1, the impact mechanism 3 includes a drive shaft 31, a reducer 32, a hammer 33, an anvil 34, and a spring 35. For ease of explanation, the direction from the hammer 33 to the anvil 34 will be referred to as the "forward" direction below.

[0033] The drive shaft 31 is disposed between the motor 2 and the output shaft 4 .

[0034] The reducer 32 reduces the rotation of the rotary shaft 21 of the motor 2 at a predetermined reduction ratio and transmits it to the drive shaft 31 .

[0035] The hammer 33 rotates by receiving power from the motor 2. The hammer 33 moves relative to the anvil 34 and applies a rotational striking force (impact force) to the anvil 34. The hammer 33 is movable in the axial direction (front-rear direction) of the drive shaft 31 relative to the drive shaft 31 and is rotatable together with the drive shaft 31. As the hammer 33 moves along the axial direction of the drive shaft 31 toward or away from the anvil 34, the hammer 33 rotates together with the drive shaft 31. The hammer 33 is also rotatable relative to the spring 35.

[0036] The anvil 34 is formed integrally with the output shaft 4. The anvil 34 faces the hammer 33 in the axial direction of the drive shaft 31. When the impact mechanism 3 is not performing an impact operation, the drive shaft 31, the hammer 33, and the anvil 34 rotate integrally.

[0037] The spring 35 is sandwiched between the reducer 32 and the hammer 33. The spring 35 in this embodiment is, for example, a conical spring. The spring 35 applies a force to the hammer 33 in a direction along the axial direction of the drive shaft 31 toward the output shaft 4 (forward).

[0038] Hereinafter, the movement of the hammer 33 in the axial direction of the drive shaft 31 toward the anvil 34 will also be referred to as "the hammer 33 moves forward." Also, hereinafter, the movement of the hammer 33 in the axial direction of the drive shaft 31 away from the anvil 34 will also be referred to as "the hammer 33 moves backward."

[0039] In the impact mechanism 3, when the tightening torque reaches or exceeds a predetermined value, an impact operation is started. That is, when the tightening torque increases, the component of the force generated between the hammer 33 and the anvil 34 in the direction of moving the hammer 33 backward also increases. When the tightening torque reaches or exceeds a predetermined value, the hammer 33 starts to move backward while compressing the spring 35. Then, the hammer 33 rotates while moving backward. When the hammer 33 and the anvil 34 are released from the connection due to the backward movement of the hammer 33, the hammer 33 receives a return force from the spring 35 and rotates while moving forward. Then, the hammer 33 applies an impact force to the anvil 34 every time the drive shaft 31 rotates approximately half a turn.

[0040] In this way, in the impact mechanism 3, the hammer 33 repeatedly applies an impact force to the anvil 34. Due to the torque caused by this impact force, the screw, the fastening member B1 can be tightened more strongly than in the absence of the impact force.

[0041] The output shaft 4 holds the tool bit 11. For example, a socket bit is attached to the output shaft 4 as the tool bit 11. The output shaft 4 transmits the rotational driving force of the motor 2 transmitted from the drive shaft 31 to the tool bit 11. This causes the tool bit 11 to rotate. The tool bit 11 rotates while the tool bit 11 is in contact with the fastening member B1, thereby enabling the work of fastening the fastening member B1 to the workpiece. The output shaft 4 also transmits the impact force transmitted from the impact mechanism 3 to the tool bit 11.

[0042] The tool bit 11 may be detachable from the output shaft 4, or may be fixed non-detachably to the output shaft 4. In this embodiment, the tool bit 11 is not a component of the impact tool 1. However, the impact tool 1 may include the tool bit 11 as a component.

[0043] The torsion measuring unit 5 includes, for example, a magnetostrictive strain sensor capable of detecting torsional strain. The torsion measuring unit 5 detects the change in magnetic permeability corresponding to the strain of the output shaft 4 caused by the application of torque to the output shaft 4, using a coil installed in the non-rotating portion. As shown in Fig. 3, the torsion measuring unit 5 outputs the measurement result as a time change in a voltage value Vt proportional to the strain of the output shaft 4. The greater the strain of the output shaft 4, the higher the voltage value Vt.

[0044] The storage unit 9 is configured with, for example, a semiconductor memory. The storage unit 9 stores various information. The storage unit 9 stores information necessary for the operation of the control unit 8, which will be described later. The storage unit 9 stores information generated by the control unit 8.

[0045] The communication unit 13 is a communication interface that performs wireless communication conforming to standards such as Wi-Fi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), or low-power radio (specified low-power radio) that does not require a license. The communication unit 13 performs wireless communication with the outside (e.g., the management server 12). Note that the communication unit 13 may be a communication interface that performs wired communication with the outside.

[0046] The control unit 8 includes a computer system having one or more processors and a memory. At least a part of the functions of the control unit 8 is realized by the processor of the computer system executing a program recorded in the memory of the computer system. The program may be recorded in the memory, or may be provided via a telecommunication line such as the Internet, or may be provided by recording it on a non-transitory recording medium such as a memory card.

[0047] 2, the control unit 8 has a motor control unit 81, a filter unit 82, an estimation unit 83, a coefficient setting unit 84, a torque calculation unit 85, and an update unit 86. Note that the motor control unit 81, the estimation unit 83, the coefficient setting unit 84, the torque calculation unit 85, and the update unit 86 are not tangible components but indicate functions realized by the control unit 8.

[0048] The motor control unit 81 controls the operation of the motor 2. The motor control unit 81 controls the on / off of the motor 2 in response to an operation performed on the operation unit 7. In addition, the motor control unit 81 controls the voltage applied to the motor 2 based on the retraction amount of the operation unit 7 to control the rotation speed of the motor 2.

[0049] The filter unit 82 smoothes the time change in the voltage value Vt proportional to the distortion of the output shaft 4, which is the measurement result of the torsion amount measurement unit 5. Specifically, the filter unit 82 smoothes the time change in the voltage value Vt (see FIG. 3), which is the raw data of the measurement result of the torsion amount measurement unit 5, and converts it into data of the time change in the voltage value Vts as shown in FIG. 4. In other words, the voltage value Vts is the smoothed voltage value Vt. The smoothing by the filter unit 82 may be performed by a known method such as moving average or Kalman filter.

[0050] The change over time of the voltage value Vts when the hammer 33 applies an impact force to the anvil 34 will be described below with reference to FIG.

[0051] When the hammer 33 collides with the anvil 34 at time t1, the clearance between the tool tip 11 and the fastening member B1 begins to close. The voltage value Vts starts to rise from an initial value of approximately 0 V at time t1. The voltage value Vts has a first maximum value P1 at time t2 within a first period ΔT1 from time t1 to time t3 at which the clearance between the tool tip 11 and the fastening member B1 becomes zero. After that, the transmission of the fastening torque from the tool tip 11 to the fastening member B1 begins at time t3. The voltage value Vts has a second maximum value P2 at time t4 within a second period ΔT2 from time t3 to time t5. Note that time t5 is the time at which the voltage value Vts reaches approximately 0 V after the hammer 33 is retracted and the connection between the hammer 33 and the anvil 34 is released.

[0052] The estimation unit 83 estimates the weight of the tool bit 11 based on information (second information) included in the change over time of the voltage value Vts. The second information includes at least the second maximum value P2. The second information also includes the first maximum value P1. Furthermore, the second information includes at least the ratio (accumulation value ratio) between a first integrated value E1 of the voltage value Vts in the first period ΔT1 and a second integrated value E2 of the voltage value Vts in the second period ΔT2. Here, the integration value ratio is a value obtained by dividing the first integration value E1 by the second integration value E2. The operation of the estimation unit 83 will be specifically described below.

[0053] For example, the estimation unit 83 determines that the time when the time derivative of the voltage value Vts (hereinafter referred to as the voltage gradient) exceeds the first threshold value is the time when the hammer 33 hits the anvil 34 (time t1). The estimation unit 83 determines that the time when the voltage gradient changes from positive to negative after time t1 is the time when the voltage value Vts becomes the first maximum value P1 (time t2). The estimation unit 83 also determines that the time when the voltage gradient changes from negative to positive after time t2 is the time when the transmission of the fastening torque from the tool bit 11 to the fastening member B1 starts (time t3). In other words, the estimation unit 83 determines that the time t3 when the voltage value Vts becomes the minimum value P3 is the end time of the first period ΔT1 and the start time of the second period ΔT2. The estimation unit 83 determines that the time when the voltage gradient changes from positive to negative after time t3 is the time when the voltage value Vts reaches the second maximum value P2 (time t4). The estimation unit 83 determines that the time when the voltage gradient exceeds the second threshold after time t4 is the time when the voltage value Vts reaches its initial value of approximately 0 V (time t5). Here, the second threshold is a negative value.

[0054] The estimation unit 83 calculates a first integrated value E1 by integrating the voltage value Vts in a first period ΔT1 (period from time t1 to time t3). The estimation unit 83 also calculates a second integrated value E2 by integrating the voltage value Vts in a second period ΔT2 (period from time t3 to time t5). The estimation unit 83 divides the first integrated value E1 by the second integrated value E2 to calculate an integrated value ratio. Here, as described above, the time change of the voltage value Vts is obtained by smoothing the time change of the voltage value Vt, which is raw data of the measurement result of the torsion amount measurement unit 5, by the filter unit 82. That is, the estimation unit 83 calculates a ratio between the first integrated value E1 of the voltage value Vt smoothed by the filter unit 82 in the first period ΔT1 and the second integrated value E2 of the voltage value Vt smoothed by the filter unit 82 in the second period ΔT2.

[0055] The estimation unit 83 estimates the weight of the tool tip 11 using a learned model that has been machine-learned to output the weight of the tool tip 11 using second information including the first maximum value P1, the second maximum value P2, and the integrated value ratio as input.

[0056] The trained model is generated in advance, for example, by a manufacturer of the impact tool 1, and stored in the storage unit 9. The trained model accepts the second information as input data, and estimates the weight of the tool tip 11 based on the input data.

[0057] The trained model is generated by supervised learning. The training data used in the supervised learning is data that associates at least the second information with the weight of the tool tip 11. In the training phase of the machine learning, the weight of the tool tip 11 may be measured in advance using a scale or the like.

[0058] As an example, the trained model calculates the weight of the tool bit 11 to be a heavier value as the integrated value ratio included in the second information increases.

[0059] An example of the machine learning algorithm is a neural network. However, the machine learning algorithm is not limited to a neural network, and may be, for example, an eXtreme Gradient Boosting (XGB) regression, a Random Forest, a decision tree, a Logistic Regression, a Support Vector Machine (SVM), a Naive Bayes classifier, or a k-nearest neighbors. Furthermore, the machine learning algorithm may be, for example, a Gaussian Mixture Model (GMM), or a k-means clustering.

[0060] The update unit 86 updates the trained model based on update information (e.g., additional learning data) from an external source (e.g., the management server 12). The update unit 86 acquires the update information from an external source via the communication unit 13.

[0061] The coefficient setting unit 84 sets a conversion coefficient used when the torque calculation unit 85 calculates the tightening torque, according to the weight of the tool bit 11 estimated by the estimation unit 83.

[0062] The torque calculation unit 85 calculates the fastening torque based on information (first information) included in the time change of the voltage value Vts. The first information includes at least the second maximum value P2. The operation of the torque calculation unit 85 will be specifically described below.

[0063] The torque calculation unit 85 determines that the time when the voltage gradient exceeds the first threshold value is the time when the hammer 33 hits the anvil 34 (time t1). Here, the first threshold value is a positive value. The torque calculation unit 85 determines that the voltage value Vts at the time when the voltage gradient changes from positive to negative after time t1 (time t2) is the first maximum value P1. Moreover, the torque calculation unit 85 determines that the voltage value Vts at the time when the voltage gradient changes from positive to negative after time t2 (time t4) is the second maximum value P2.

[0064] The torque calculation unit 85 performs a conversion process using a conversion coefficient on the second maximum value P2, which is the first information, to calculate the tightening torque applied from the output shaft 4 via the tool tip 11 to the fastening member B1. Specifically, the torque calculation unit 85 calculates the tightening torque by multiplying the second maximum value P2 by the conversion coefficient. As described above, the conversion coefficient is set by the coefficient setting unit 84 in accordance with the weight of the tool tip 11. More specifically, the coefficient setting unit 84 sets the conversion coefficient so that the value of the tightening torque calculated by the torque calculation unit 85 becomes smaller as the weight of the tool tip 11 estimated by the estimation unit 83 becomes heavier.

[0065] (3) Advantages The advantages of the impact tool 1 will be described below with reference to FIGS.

[0066] 4 is a graph showing the change over time in the voltage value Vts (VtsA) when the output shaft 4 holds a relatively light tool bit 11 (11A). The voltage value VtsA has a first maximum value P1 (P1A) during a first period ΔT1 (ΔT1A) from time t1 (t1A) to time t3 (t3A), and a second maximum value P2 (P2A) during a second period ΔT2 (ΔT2A) from time t3A to time t5 (time t5A). The voltage value VtsA has a minimum value P3 (P3A) at time t3 (t3A).

[0067] 5 is a graph showing the change over time in the voltage value Vts (VtsB) when the output shaft 4 holds the tool bit 11 (11B) that is heavier than the tool bit 11A. The voltage value VtsB has a first maximum value P1 (P1B) during a first period ΔT1 (ΔT1B) from time t1 (t1B) to time t3 (t3B), and a second maximum value P2 (P2B) during a second period ΔT2 (ΔT2B) from time t3B to time t5 (time t5B). The voltage value VtsB has a minimum value P3 (P3B) at time t3 (t3B).

[0068] The first accumulated value E1 and the second accumulated value E2 corresponding to the tool tip 11A are referred to as the first accumulated value E1A and the second accumulated value E2A, and the first accumulated value E1 and the second accumulated value E2 corresponding to the tool tip 11B are referred to as the first accumulated value E1B and the second accumulated value E2B.

[0069] In the impact tool 1, even if the rotation speed of the motor 2 is the same, it is known that the heavier the tool bit 11 is, the greater the torque required to rotate the tool bit 11 becomes, and therefore the true value of the tightening torque applied to the fastening member B1 via the tool bit 11 decreases. The true value of the tightening torque is, for example, a value measured by a torque measuring device provided separately from the impact tool 1.

[0070] However, when the rotation speed of the motor 2 is the same and the weight of the tool tip 11 is different, the second maximum value P2A and the second maximum value P2B may be substantially equal. Even in such a case, the second information including the first maximum value P1, the second maximum value P2, and the integrated value ratio varies depending on the weight of the tool tip 11, as shown in Figs. 4 and 5. Specifically, the heavier the tool tip 11 is, the larger the relative magnitude of the first maximum value P1 to the second maximum value P2 becomes. Also, the relative magnitude of the first integrated value E1 to the second integrated value E2 becomes larger. As a result, the integrated value ratio (E1B / E2B) corresponding to the tool tip 11B becomes larger than the integrated value ratio (E1A / E2A) corresponding to the tool tip 11A.

[0071] The impact tool 1 sets the conversion coefficient so that the heavier the weight of the tool tip 11 estimated based on the second information, the smaller the value of the tightening torque calculated by the torque calculation unit 85. Therefore, even when the second maximum value P2A and the second maximum value P2B are substantially equal, the tightening torque that reflects the weight of the tool tip 11 can be calculated, and the calculation accuracy of the tightening torque can be improved.

[0072] (4) Variations The above embodiment is merely one of various embodiments of the present disclosure. The above embodiment can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. In addition, the same function as the impact tool 1 according to the above embodiment may be embodied in a control method for the impact tool 1, a (computer) program, or a non-transitory recording medium on which a computer program is recorded, etc.

[0073] A control method according to one embodiment is a control method for an impact tool 1 including a motor 2, a hammer 33, an anvil 34, and an output shaft 4. The hammer 33 rotates by receiving power from the motor 2. The anvil 34 rotates by receiving an impact force from the hammer 33 in the rotation direction of the hammer 33. The output shaft 4 is configured to hold a tool tip 11 that tightens the fastening member B1, and rotates together with the anvil 34. The control method includes a twist amount measurement step, a torque calculation step, an estimation step, and a coefficient setting step. In the twist amount measurement step, a twist amount of the output shaft 4 when the hammer 33 applies an impact force to the anvil 34 is measured. In the torque calculation step, a conversion process is performed using a conversion coefficient on the first information included in the measurement result in the twist amount measurement step, thereby calculating a tightening torque applied to the fastening member B1 from the output shaft 4 via the tool tip 11. In the estimation step, the weight of the tool bit 11 is estimated using a trained model that has been machine-learned to output the weight of the tool bit 11 using the second information included in the measurement result in the twist amount measurement step as an input. In the coefficient setting step, a conversion coefficient is set according to the weight of the tool bit 11 estimated in the estimation step. In the twist amount measurement step, the measurement result is output as a time change in the voltage value Vts. The voltage value Vts has a first maximum value P1 in a first period ΔT1 and has a second maximum value P2 in a second period ΔT2 following the first period ΔT1. The first information includes at least the second maximum value P2.

[0074] A program according to one aspect is a program for causing one or more processors to execute the above-described control method.

[0075] Modifications of the embodiment are listed below. The above embodiment and the modifications described below can be applied in appropriate combination.

[0076] The torque calculation unit 85 may estimate the tightening torque using a trained model that is machine-learned to input the second information including the first maximum value P1, the second maximum value P2, and the integrated value ratio (the ratio between the first integrated value E1 of the voltage value Vts in the first period ΔT1 and the second integrated value E2 of the voltage value Vts in the second period ΔT2). The trained model is generated in advance by, for example, a manufacturer of the impact tool 1, and stored in the storage unit 9. The trained model accepts the second information as input data, and estimates the tightening torque based on the input data. The trained model is generated by supervised learning. The learning data used in supervised learning is data that associates at least the second information with the true value of the tightening torque. In the training phase of the machine learning, the true value of the tightening torque is measured, for example, by a torque measuring device provided separately from the impact tool 1. Here, the machine learning algorithm is, for example, a neural network. However, the machine learning algorithm is not limited to a neural network, and may be, for example, an eXtreme Gradient Boosting (XGB) regression, a Random Forest, a decision tree, a Logistic Regression, a Support Vector Machine (SVM), a Naive Bayes classifier, or a k-nearest neighbors method, etc. Furthermore, the machine learning algorithm may be, for example, a Gaussian Mixture Model (GMM), or a k-means clustering method, etc.

[0077] The impact tool 1 in the present disclosure includes a computer system in the control unit 8. The computer system is mainly composed of a processor and a memory as hardware. The function of the control unit 8 in the present disclosure is realized by the processor executing a program recorded in the memory of the computer system. The program may be pre-recorded in the memory of the computer system, may be provided through an electric communication line, or may be provided by being recorded in a non-transitory recording medium such as a memory card, an optical disk, or a hard disk drive that can be read by the computer system. The processor of the computer system is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or a large scale integrated circuit (LSI). The integrated circuits such as IC or LSI are called differently depending on the degree of integration. The integrated circuits such as IC or LSI include integrated circuits called system LSI, VLSI (Very Large Scale Integration), or ULSI (Ultra Large Scale Integration). Furthermore, a field-programmable gate array (FPGA) that is programmed after the manufacture of the LSI, or a logic device that can reconfigure the joint relationship inside the LSI or reconfigure the circuit partition inside the LSI, can also be adopted as the processor. The electronic circuits may be integrated in one chip or distributed among multiple chips. The chips may be integrated in one device or distributed among multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Thus, the microcontroller is also composed of one or more electronic circuits including a semiconductor integrated circuit or a large-scale integrated circuit.

[0078] (5) Summary As described above, the impact tool (1) of the first aspect includes the motor (2), the hammer (33), the anvil (34), the output shaft (4), the twist amount measuring unit (5), the torque calculating unit (85), the estimating unit (83), and the coefficient setting unit (84). The hammer (33) rotates by receiving power from the motor (2). The anvil (34) rotates by receiving an impact force from the hammer (33) in the rotation direction of the hammer (33). The output shaft (4) is configured to hold the tool tip (11) that tightens the fastening member (B1), and rotates together with the anvil (34). The twist amount measuring unit (5) measures the twist amount of the output shaft (4) when the hammer (33) applies an impact force to the anvil (34). The torque calculation unit (85) calculates the tightening torque applied to the fastening member (B1) from the output shaft (4) via the tool tip (11) by performing a conversion process using a conversion coefficient on the first information included in the measurement result of the torsion amount measurement unit (5). The estimation unit (83) estimates the weight of the tool tip (11) using a trained model that has been machine-learned to output the weight of the tool tip (11) using the second information included in the measurement result of the torsion amount measurement unit (5) as input. The coefficient setting unit (84) sets the conversion coefficient according to the weight of the tool tip (11) estimated by the estimation unit (83). The torsion amount measurement unit (5) outputs the measurement result as a time change in the voltage value (Vts). The voltage value (Vts) has a first maximum value (P1) in a first period (ΔT1) and a second maximum value (P2) in a second period (ΔT2) following the first period (ΔT1). The first information includes at least the second maximum value (P2).

[0079] According to this embodiment, the tightening torque can be calculated in such a way that the weight of the tool bit (11) is reflected therein, thereby improving the accuracy of the tightening torque calculation.

[0080] In the impact tool (1) of the second aspect, in the first aspect, the second information includes at least the second maximum value (P2).

[0081] According to this embodiment, the tightening torque can be calculated in such a way that the weight of the tool bit (11) is reflected therein, thereby improving the accuracy of the tightening torque calculation.

[0082] In the third aspect of the impact tool (1), in the first or second aspect, the second information includes at least a ratio between a first accumulated value (E1) of the voltage value (Vts) in the first period (ΔT1) and a second accumulated value (E2) of the voltage value (Vts) in the second period (ΔT2).

[0083] According to this aspect, the tightening torque can be calculated in such a way that the weight of the tool bit (11) is reflected therein, thereby making it possible to further improve the accuracy of the tightening torque calculation.

[0084] In the fourth aspect of the impact tool (1), in the third aspect, the estimation unit (83) determines the point at which the voltage value (Vts) reaches a minimum value (P3) as the end point of the first period (ΔT1) and the start point of the second period (ΔT2).

[0085] According to this embodiment, the ratio between the first integrated value (E1) and the second integrated value (E2) can be calculated with high accuracy.

[0086] The impact tool (1) of the fifth aspect is the impact tool (1) of the third or fourth aspect, further including a filter unit (82) that smoothes a time change of the voltage value (Vt). The estimation unit (83) calculates a ratio between a first integrated value (E1) of the voltage value (Vt) smoothed by the filter unit (82) in a first time period (ΔT1) and a second integrated value (E2) of the voltage value (Vt) smoothed by the filter unit (82) in a second time period (ΔT2).

[0087] According to this embodiment, the ratio between the first integrated value (E1) and the second integrated value (E2) can be calculated with high accuracy.

[0088] The impact tool (1) of a sixth aspect is any one of the first to fifth aspects, further including an update unit (86) that updates the trained model based on update information from outside.

[0089] According to this embodiment, the accuracy of estimating the weight of the bit (11) can be improved.

[0090] In the seventh aspect of the impact tool (1), in any of the first to sixth aspects, the coefficient setting unit (84) sets the conversion coefficient so that the torque value calculated by the torque calculation unit (85) becomes smaller as the weight of the bit (11) estimated by the estimation unit (83) becomes heavier.

[0091] According to this embodiment, it is possible to reduce the possibility that the fastening operation of the fastening member (B1) is completed with an insufficient fastening torque.

[0092] The control method of the eighth aspect is a control method for an impact tool (1) including a motor (2), a hammer (33), an anvil (34), and an output shaft (4). The hammer (33) rotates by receiving power from the motor (2). The anvil (34) rotates by receiving an impact force from the hammer (33) in the rotational direction of the hammer (33). The output shaft (4) is configured to hold a tool tip (11) that tightens the fastening member (B1), and rotates together with the anvil (34). The control method includes a twist amount measuring step, a torque calculating step, an estimation step, and a coefficient setting step. In the twist amount measuring step, the twist amount of the output shaft (4) is measured when the hammer (33) applies an impact force to the anvil (34). In the torque calculation step, a conversion process is performed using a conversion coefficient on the first information included in the measurement result in the torsion amount measurement step to calculate the tightening torque applied to the fastening member (B1) from the output shaft (4) via the tool tip (11). In the estimation step, the weight of the tool tip (11) is estimated using a trained model that is machine-learned to input the second information included in the measurement result in the torsion amount measurement step and output the weight of the tool tip (11). In the coefficient setting step, a conversion coefficient is set according to the weight of the tool tip (11) estimated in the estimation step. In the torsion amount measurement step, the measurement result is output as a time change in the voltage value (Vts). The voltage value (Vts) has a first maximum value (P1) in a first period (ΔT1) and a second maximum value (P2) in a second period (ΔT2) following the first period (ΔT1). The first information includes at least the second maximum value (P2).

[0093] According to this embodiment, the tightening torque can be calculated in such a way that the weight of the tool bit (11) is reflected therein, thereby improving the accuracy of the tightening torque calculation.

[0094] A program according to a ninth aspect is a program for causing one or more processors to execute the control method according to the eighth aspect.

[0095] According to this embodiment, the tightening torque can be calculated in such a way that the weight of the tool bit (11) is reflected therein, thereby improving the accuracy of the tightening torque calculation. [Explanation of symbols]

[0096] 1 Impact tool 2 Motors 4 Output Shaft 5. Twist measurement section 11 Tip tools 33 Hammer 34 Anvil 82 Filter section 83 Estimation part 84 Coefficient setting section 85 Torque calculation section 86 Update section B1 Fastening member E1 First integrated value E2 Second integrated value P1 First maximum P2 Second maximum P3 Minimum Vt, Vts voltage values ΔT1 First period ΔT2 Second Period

Claims

1. A motor; a hammer that rotates by receiving power from the motor; an anvil that rotates by receiving an impact force from the hammer in the rotational direction of the hammer; An output shaft configured to hold a tool tip for tightening a fastening member and rotate together with the anvil; a torsion amount measuring unit that measures an amount of torsion of the output shaft when the hammer applies the impact force to the anvil; a torque calculation unit that calculates a tightening torque applied to the fastening member from the output shaft via the tool bit by performing a conversion process using a conversion coefficient on first information included in a measurement result of the torsion amount measurement unit; an estimation unit that estimates a weight of the tool bit by using a trained model that has been machine-learned to input second information included in the measurement result of the twist amount measurement unit and output the weight of the tool bit; a coefficient setting unit that sets the conversion coefficient in accordance with the weight of the tool bit estimated by the estimation unit, the torsion amount measuring unit outputs a measurement result as a time change of a voltage value; the voltage value has a first maximum value in a first period and has a second maximum value in a second period following the first period; The first information includes at least the second maximum value. Impact tool.

2. The second information includes at least the second maximum value.

2. The impact tool according to claim 1.

3. the second information includes at least a ratio between a first integrated value of the voltage value in the first period and a second integrated value of the voltage value in the second period; An impact tool according to claim 1 or 2.

4. The estimation unit determines a time point at which the voltage value takes a minimum value as an end time point of the first period and a start time point of the second period.

4. An impact tool according to claim 3.

5. The filter unit smoothes the change in the voltage value over time. the estimation unit calculates a ratio between a first integrated value of the voltage value smoothed by the filter unit in the first time period and a second integrated value of the voltage value smoothed by the filter unit in the second time period; 4. An impact tool according to claim 3.

6. Further comprising an update unit that updates the trained model based on update information from an external source. An impact tool according to claim 1 or 2.

7. The coefficient setting unit sets the conversion coefficient so that the value of the tightening torque calculated by the torque calculation unit becomes smaller as the weight of the tool bit estimated by the estimation unit becomes heavier. An impact tool according to claim 1 or 2.

8. A control method for an impact tool including a motor, a hammer that receives power from the motor to rotate, an anvil that receives an impact force from the hammer in a rotational direction of the hammer to rotate, and an output shaft that is configured to hold a tool tip that tightens a fastening member and rotates together with the anvil, a torsion amount measuring step of measuring an amount of torsion of the output shaft when the hammer applies the impact force to the anvil; a torque calculation step of calculating a tightening torque applied to the fastening member from the output shaft via the tool bit by performing a conversion process using a conversion coefficient on first information included in a measurement result in the torsion amount measurement step; an estimation step of estimating a weight of the tool bit by using a trained model that has been machine-learned to input second information included in the measurement result in the twist amount measurement step and output the weight of the tool bit; a coefficient setting step of setting the conversion coefficient in accordance with the weight of the tool bit estimated in the estimation step, In the torsion amount measuring step, a measurement result is output as a time change of a voltage value, the voltage value has a first maximum value in a first period and has a second maximum value in a second period following the first period; The first information includes at least the second maximum value. Control methods.

9. A program for causing one or more processors to execute the control method according to claim 8.

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