Impact tool, control method, and program

Abstract

To improve efficiency of a work.SOLUTION: An impact tool 1 includes: a motor 2; a hammer; an anvil; an output shaft; and a motor control section 81. The hammer rotates by obtaining power from the motor 2. The anvil rotates by receiving impact force in a rotation direction of the hammer from the hammer. The output shaft is configured to hold a tip tool and rotates together with the anvil. The motor control section 81 controls the number of rotations of the motor 2 according to a joint rate. The joint rate is a value divided by first increase amount and second increase amount. The first increase amount is a difference between first torque applied to the output shaft by a first strike that the hammer applies impact force to the anvil and second torque applied to the output shaft by a second strike that the hammer applies impact force to the anvil subsequently to the first strike. The second increase amount is increase amount of a rotation angle of the output shaft until the second torque is applied after the first torque is applied.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 improving the efficiency of the work of fastening a screw member.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and an object of the present disclosure is to provide an impact tool, a control method, and a program that can improve work efficiency. [Means for solving the problem]

[0006] An impact tool according to an embodiment of the present disclosure includes a motor, a hammer, an anvil, an output shaft, and a motor control 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 and rotates together with the anvil. The motor control unit controls the rotation speed of the motor according to a joint rate. The joint rate is a value obtained by dividing a first increase by a second increase. The first increase is a difference between a first torque applied to the output shaft by a first blow in which the hammer applies the impact force to the anvil, and a second torque applied to the output shaft by a second blow in which the hammer applies the impact force to the anvil following the first blow. The second increase is an increase in a rotation angle of the output shaft from when the first torque is applied to when the second torque is applied.

[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 that receives power from the motor to rotate, an anvil that receives an impact force from the hammer in the rotation direction of the hammer to rotate, and an output shaft that is configured to hold a tool tip and rotates together with the anvil. The control method includes a motor control step of controlling a rotation speed of the motor according to a joint rate. The joint rate is a value obtained by dividing a first increment by a second increment. The first increment is a difference between a first torque applied to the output shaft by a first blow in which the hammer applies the impact force to the anvil, and a second torque applied to the output shaft by a second blow in which the hammer applies the impact force to the anvil following the first blow. The second increment is an increase in a rotation angle of the output shaft from when the first torque is applied to when the second torque is applied.

[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 can improve work efficiency. [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 the change in tightening torque over time when the impact tool is performing an impact operation. [Figure 4] FIG. 4 is a graph showing the relationship between the rotation angle of the rotating shaft and the tightening torque when the impact tool is performing an impact operation. [Diagram 5] FIG. 5 is a block diagram showing a configuration of the impact tool of the first modification. [Figure 6] FIG. 6 is a block diagram showing a configuration of an impact tool according to the second modification. [Figure 7] FIG. 7 is a block diagram showing a configuration of an impact tool according to the third modification. [Figure 8] FIG. 8 is a block diagram showing a configuration of an impact tool according to the fourth modification. 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.

[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 FIGS. 1 and 2, the impact tool 1 includes a motor 2, a hammer 33, an anvil 34, an output shaft 4, and a motor control unit 81.

[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 the tool tip 11 and rotates together with the anvil 34 .

[0018] The motor control unit 81 controls the rotation speed of the motor 2 according to the joint rate. The joint rate is a value obtained by dividing the first increment by the second increment. As shown in Figs. 3 and 4, the first increment is the difference between the torque (first torque TQ1) applied to the output shaft 4 by the first blow in which the hammer 33 applies an impact force to the anvil 34, and the torque (second torque TQ2) applied to the output shaft 4 by the second blow in which the hammer 33 applies an impact force to the anvil 34 following the first blow. The second increment is the increment in the rotation angle of the output shaft 4 from the application of the first torque TQ1 to the application of the second torque TQ2. The torque applied to the output shaft 4 is, in other words, the torque applied to the fastening member B1. Hereinafter, the torque applied to the output shaft 4 is referred to as the fastening torque.

[0019] In the following description, the rotation angle of the output shaft 4 when the fastening torque is the first torque TQ1 (hereinafter sometimes simply referred to as the rotation angle) is defined as angle θ1, and the rotation angle when the fastening torque is the second torque TQ2 is defined as angle θ2. In other words, during the period Ti (see FIG. 3) when the fastening torque changes from the first torque TQ1 to the second torque TQ2, the rotation angle changes from angle θ1 to angle θ2, as shown in FIG.

[0020] Here, it is known that the tightening torque changes linearly with respect to the rotation angle of the output shaft 4 while the rotation angle changes from angle θ1 to angle θ2. In other words, the joint rate indicates the increase in tightening torque per unit rotation angle of the output shaft 4. When fastening one type of fastening member B1, the joint rate will have different values ​​depending on the material of the fastened members, the fixing state of the fastened members, etc.

[0021] The smaller the joint rate, the more rotations the output shaft 4 must make before the tightening torque reaches the target value, which reduces the efficiency of the tightening work.

[0022] The impact tool 1 of the present embodiment controls the rotation speed of the motor 2 in accordance with the joint rate, thereby making it possible to suppress an increase in the time required for the tightening torque to reach a target value, and to improve the efficiency of work.

[0023] (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 torque measuring unit 5, an angle measuring unit 6, an operation unit 7, a control unit 8, and a memory unit 9.

[0024] 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.

[0025] 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.

[0026] The operation unit 7 receives an operation for controlling the rotation of the motor 2. By pulling the operation unit 7, the motor 2 can be switched on and off.

[0027] 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 .

[0028] 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.

[0029] The drive shaft 31 is disposed between the motor 2 and the output shaft 4 .

[0030] 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 .

[0031] 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.

[0032] 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.

[0033] 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).

[0034] 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."

[0035] 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.

[0036] 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.

[0037] The output shaft 4 holds the tool bit 11. For example, a socket bit 111 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.

[0038] The tool tip 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 tip 11 such as the socket bit 111 is not a component of the impact tool 1. However, the impact tool 1 may include the tool tip 11 as a component.

[0039] The torque measuring unit 5 measures the tightening torque applied by the output shaft 4. The torque measuring unit 5 of this embodiment includes, for example, a magnetostrictive strain sensor capable of detecting torsional strain. The torque measuring unit 5 detects a 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 a non-rotating portion. That is, the torque measuring unit 5 indirectly measures the tightening torque by measuring the torque applied to the output shaft 4 based on the torsion of the output shaft 4. The torque measuring unit 5 outputs a voltage signal proportional to the strain of the output shaft 4 to the control unit 8.

[0040] The angle measuring unit 6 measures the rotation angle of the output shaft 4. The angle measuring unit 6 includes, for example, a rotary encoder. The angle measuring unit 6 outputs a digital signal indicating the measured rotation angle of the output shaft 4 to the control unit 8. The angle measuring unit 6 starts measuring the rotation angle, for example, from the point in time when the operation unit 7 is operated and the motor 2 is turned on. The angle measuring unit 6 measures the rotation angle by setting the rotation angle at the point in time when the motor 2 is turned on as 0°.

[0041] 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. The storage unit 9 stores information generated by the control unit 8.

[0042] 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.

[0043] 2, the control unit 8 has a motor control unit 81, a torque calculation unit 82, an angle calculation unit 83, and a determination unit 84. Note that the motor control unit 81, the torque calculation unit 82, the angle calculation unit 83, and the determination unit 84 are not tangible components, but indicate functions realized by the control unit 8.

[0044] 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.

[0045] Moreover, the motor control unit 81 controls the rotation speed of the motor 2 in accordance with a joint rate determined by a determination unit 84, which will be described later.

[0046] The torque calculation unit 82 calculates the tightening torque based on the measurement result by the torque measurement unit 5. The torque calculation unit 82 acquires a signal output from the torque measurement unit 5, and calculates the tightening torque based on the distortion of the output shaft 4 indicated by the acquired signal.

[0047] The angle calculation unit 83 calculates the rotation angle of the output shaft 4. The angle calculation unit 83 calculates the rotation angle of the output shaft 4 based on the measurement result by the angle measurement unit 6. The angle calculation unit 83 acquires a signal output from the angle measurement unit 6, and calculates the rotation angle of the output shaft 4 based on the acquired signal.

[0048] The determination unit 84 determines a joint rate that indicates an increase in the fastening torque per unit rotation angle of the output shaft 4 based on a second increase in the rotation angle of the output shaft 4 from when the first torque TQ1 is applied to when the second torque TQ2 is applied. The function of the determination unit 84 will be described in detail in "(3) Operation".

[0049] (3) Operation Hereinafter, the impact operation of the impact tool 1 and the control of the rotation speed of the motor 2 according to the joint rate during the impact operation will be described with reference to FIGS.

[0050] Fig. 3 is a graph showing the change over time in the tightening torque calculated by the torque calculation unit 82 when the impact tool 1 is performing an impact operation. Fig. 4 is a graph showing the relationship between the rotation angle of the output shaft 4 calculated by the angle calculation unit 83 and the tightening torque when the impact tool 1 is performing an impact operation. The rotation angle calculated by the angle calculation unit 83 and the tightening torque calculated by the torque calculation unit 82 are stored in the memory unit 9 at any time.

[0051] 3, at time t1, the hammer 33 delivers a first blow to the anvil 34. The tightening torque starts to increase from approximately 0 at time t1.

[0052] At time t2, the tightening torque reaches the first torque TQ1, and the hammer 33 and the anvil 34 are disengaged. As a result, the tightening torque starts to decrease. At time t2, the rotation angle becomes angle θ1, as shown in Fig. 4. At time t2, the output shaft 4 stops rotating, and the rotation angle stops increasing.

[0053] Next, at time t3, when the hammer 33 delivers a second blow following the first blow to the anvil 34, the tightening torque starts to increase. Also at time t3, the output shaft 4 starts to rotate, and the rotation angle starts to increase.

[0054] At time t4, the tightening torque reaches the second torque TQ2. The second torque TQ2 is greater than the first torque TQ1. At this time, as shown in FIG. 4, the rotation angle becomes angle θ2. At time t4, the hammer 33 and the anvil 34 are disengaged. As a result, the tightening torque starts to decrease. At time t4, the output shaft 4 stops rotating, and the rotation angle stops increasing.

[0055] In the calculation process of the joint rate, the determination unit 84 determines the time points (time points t2 and t4) at which the first torque TQ1 and the second torque TQ2 are applied to the output shaft 4 based on, for example, the change rate of the fastening torque. Specifically, the determination unit 84 determines that the time point t2 is the time point at which the first torque TQ1 is applied to the output shaft 4 because, at time point t2, the fastening torque changes from an increase to a decrease and the change rate of the fastening torque exceeds the threshold value. In addition, the determination unit 84 determines that the time point t4 is the time point at which the second torque TQ2 is applied to the output shaft 4 because, at time point t4 after time point t2, the fastening torque changes from an increase to a decrease and the change rate of the fastening torque exceeds the threshold value. The time point at which the fastening torque is calculated is acquired, for example, by a timer function of the control unit 8. In addition, the threshold value of the change rate of the fastening torque is stored in advance in the storage unit 9.

[0056] The determination unit 84 calculates the joint rate by dividing a first increase in the fastening torque during a period Ti from time t2 to time t4 (the difference between the first torque TQ1 and the second torque TQ2) by a second increase in the rotation angle of the output shaft 4 during the period Ti (the difference between the angle θ1 and the angle θ2). In other words, the joint rate is (TQ2-TQ1) / (θ2-θ1).

[0057] When the joint rate is calculated by the determination unit 84, the motor control unit 81 controls the motor 2 at a rotation speed corresponding to the joint rate. Here, the correspondence between the joint rate and the rotation speed of the motor 2 is stored in advance in, for example, the storage unit 9. Specifically, the motor control unit 81 controls the motor 2 so that the rotation speed increases as the joint rate decreases.

[0058] As a result, the smaller the joint rate is, the stronger the impact force that the hammer 33 applies to the anvil 34, allowing the output shaft 4 to rotate faster during the impact operation. This makes it possible to prevent the time it takes for the tightening torque to reach the target value from becoming long, improving work efficiency.

[0059] (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.

[0060] A control method according to one embodiment is a control method for an impact tool 1 including a motor 2, a hammer 33 that rotates by receiving power from the motor 2, an anvil 34 that rotates by receiving an impact force from the hammer 33 in the rotation direction of the hammer 33, and an output shaft 4 that is configured to hold a tool bit 11 and rotates together with the anvil 34. The control method includes a motor control step of controlling the rotation speed of the motor 2 according to a joint rate. The joint rate is a value obtained by dividing a first increment by a second increment. The first increment is a difference between a first torque TQ1 applied to the output shaft 4 by a first blow in which the hammer 33 applies an impact force to the anvil 34, and a second torque TQ2 applied to the output shaft 4 by a second blow in which the hammer 33 applies an impact force to the anvil 34 following the first blow. The second increment is an increment in the rotation angle of the output shaft 4 from when the first torque TQ1 is applied to when the second torque TQ2 is applied.

[0061] A program according to one aspect is a program for causing one or more processors to execute the above-described control method.

[0062] Modifications of the embodiment are listed below. Hereinafter, the above embodiment may be referred to as a "basic example." The basic example and the modifications described below may be combined as appropriate and applied.

[0063] (4.1) Variation 1 The determination unit 84 of the impact tool 1 (1A) (see FIG. 5) according to the first modification can determine the joint rate based on the second increment and preset setting data.

[0064] The control unit 8 of the impact tool 1A further includes a setting data generating unit 85, as shown in FIG.

[0065] The operation modes of the impact tool 1A include a first mode and a second mode.

[0066] In the first mode, the setting data generating unit 85 generates setting data from a plurality of pieces of data on second increments and a plurality of pieces of data on joint rates corresponding to the respective plurality of second increments, which are obtained by performing the joint rate determination operation by the determining unit 84 a plurality of times. Here, the joint rate determination operation is performed a plurality of times in the first mode, for example, in the same manner as in the above embodiment. Moreover, the joint rate determination operation is performed a plurality of times in the first mode in the fastening operation of one type of fastening member B1. That is, one piece of setting data is generated for one type of fastening member B1.

[0067] The setting data is data that indicates the correspondence between multiple (e.g., four) non-overlapping increase amount ranges (increase amount ranges Δθ1 to Δθ4) and multiple (e.g., four) candidate rates (candidate rates a1 to a4) that respectively correspond to each increase amount range, as shown in Table 1.

[0068] As an example, the setting data generating unit 85 classifies each of the multiple second increase amount data into one of the increase amount ranges Δθ1 to Δθ4. Also, the setting data generating unit 85 sets the average value of multiple joint rates corresponding to multiple second increases included in each increase amount range as the candidate rates a1 to a4 corresponding to each increase amount range.

[0069] The setting data is stored in the storage unit 9, for example.

[0070] [Table 1]

[0071] In the second mode, the determination unit 84 determines the joint rate based on the second increment in the rotation angle of the output shaft 4 during the period Ti and preset setting data. More specifically, the joint rate determination unit selects a corresponding increment range that is an increment range that includes the second increment from among the increment ranges Δθ1 to Δθ4, and determines a candidate rate that corresponds to the corresponding increment range from among the candidate rates a1 to a4 as the joint rate.

[0072] When the joint rate is calculated by the determination unit 84, the motor control unit 81 controls the motor 2 at a rotation speed corresponding to the joint rate. In the second mode, the motor control unit 81 controls the motor 2 so that the rotation speed of the motor 2 changes stepwise according to the joint rate that is one of the candidate rates a1 to a4. In other words, in the second mode, the rotation speed of the motor 2 can take a value corresponding to one of the candidate rates a1 to a4.

[0073] The setting data may be generated by an external device (external server, etc.) outside the impact tool 1. In this case, the impact tool 1 receives the setting data generated outside and stores it in the storage unit 9.

[0074] (4.2) Variation 2 The determination unit 84 of the impact tool 1 (1B) according to the second modification (see FIG. 6) is capable of calculating the joint rate by using the relational expression between the second increase amount in the period Ti and the joint rate.

[0075] The control unit 8 of the impact tool 1B further includes a relational equation generating unit 86, as shown in FIG.

[0076] The operation modes of the impact tool 1B include a first mode and a second mode.

[0077] In the first mode, the relational expression generating unit 86 generates a relational expression (approximation expression) between the second increment and the joint rate from a plurality of pieces of data on the second increment and a plurality of pieces of data on the joint rates corresponding to the plurality of second increments, which are obtained by performing the joint rate determination operation a plurality of times. Here, the joint rate determination operation is performed a plurality of times in the first mode, for example, in the same manner as in the above embodiment. In addition, the joint rate determination operation is performed a plurality of times in the first mode in the fastening operation of one type of fastening member B1. In other words, one relational expression is generated for one type of fastening member B1. Note that a known method such as the least squares method may be used to generate the relational expression (approximation expression) between the second increment and the joint rate.

[0078] The relational equation generated by the relational equation generating unit 86 is stored in the storage unit 9, for example.

[0079] In the second mode, the determination unit 84 calculates the joint rate by substituting the second increment in the rotation angle of the output shaft 4 during the period Ti into the relational expression stored in the storage unit 9.

[0080] When the joint rate is calculated by the determination unit 84, the motor control unit 81 controls the motor 2 at a rotation speed corresponding to the joint rate.

[0081] The relational equation may be generated by an external device (external server, etc.) outside the impact tool 1. In this case, the impact tool 1 may receive the relational equation generated externally and store it in the storage unit 9.

[0082] (4.3) Variation 3 The determination unit 84 of the impact tool 1 (1C) (see FIG. 7) relating to the modified example 3 is capable of determining the joint rate using a trained model that has been machine-learned to use the second increase amount as an input and output the joint rate.

[0083] The trained model is generated in advance by, for example, a manufacturer of the impact tool 1C and stored in the storage unit 9. The trained model receives the second increment as input data, and determines the joint rate based on the input data. Note that the trained model may receive the length of the period Ti, etc., as input data in addition to the second increment.

[0084] The trained model is generated by supervised learning. The training data used in the supervised learning is data that associates at least the second increment with the joint rate.

[0085] In the training phase of the machine learning, the joint rate is calculated by dividing the first increase in the tightening torque by the second increase in the rotation angle of the output shaft 4, as in the above embodiment.

[0086] As an example, the trained model calculates a smaller joint rate as the second increase amount increases.

[0087] 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. Furthermore, the machine learning algorithm may be, for example, a Gaussian Mixture Model (GMM), or a k-means clustering.

[0088] Here, the trained model is updated based on information (additional learning data) from outside (e.g., management server 12).

[0089] Specifically, the control unit 8 of the impact tool 1C further includes an update unit 87 that updates the learned model used by the determination unit 84 based on information from the outside. The update unit 87 acquires the information from the outside via the communication unit 13 included in the impact tool 1C. The communication unit 13 is a communication interface that performs wireless communication in compliance with standards such as Wi-Fi (registered trademark), Bluetooth (registered trademark), ZigBee (registered trademark), or low-power wireless (specific low-power wireless) that does not require a license. The communication unit 13 performs wireless communication with the outside, but may also perform wired communication with the outside.

[0090] (4.4) Variation 4 The motor control unit 81 of the impact tool 1 (1D) according to the fourth modification (see FIG. 8) can control the rotation speed of the motor 2 in accordance with the joint rate designated by the designation information.

[0091] As shown in FIG. 8, the control unit 8 of the impact tool 1D further includes an acquisition unit 88 that acquires designation information for designating the joint rate from an external source (eg, the management server 12).

[0092] When the acquisition unit 88 acquires the designation information from the outside, the motor control unit 81 controls the rotation speed of the motor 2 according to the joint rate designated by the designation information. The acquisition unit 88 acquires the designation information from the outside via the communication unit 13 provided in the impact tool 1C. 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 that does not require a license (specific low-power radio). The communication unit 13 performs wireless communication with the outside, but may also perform wired communication with the outside.

[0093] (4.5) Variation 5 The angle calculation unit 83 may calculate the second increase amount based on the period Ti from when the first torque TQ1 is applied to the output shaft 4 until the second torque TQ2 is applied thereto (the period from time t2 to time t4 in FIG. 3).

[0094] Specifically, during the period Ti, the period from time t2 when the hammer 33 and the anvil 34 are released to time t3 when the hammer 33 applies an impact force to the anvil 34 again is a period during which the hammer 33 rotates idle for approximately half a rotation, and is therefore determined by the number of revolutions of the motor 2, regardless of the joint rate. The second increment increases in proportion to the period from time t3 when the output shaft 4 starts to rotate due to the impact force applied to the anvil 34 by the hammer 33 to time t4 when the hammer 33 and the anvil 34 are released and the output shaft 4 stops rotating. Therefore, a proportionality coefficient between the period from time t3 to time t4 and the second increment can be obtained from a set of data on the length of the period Ti, the second increment, and the number of revolutions of the motor 2. This enables the angle calculation unit 83 to calculate the second increment based on the length of the period Ti.

[0095] (4.6) Other Modifications 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.

[0096] (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), and the motor control unit (81). 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 the tool bit (11) and rotates together with the anvil (34). The motor control unit (81) controls the rotation speed of the motor (2) in accordance with the joint rate. The joint rate is a value obtained by dividing the first increase by the second increase. The first increment is the difference between a first torque TQ1 applied to the output shaft 4 by a first blow in which the hammer 33 applies an impact force to the anvil 34, and a second torque TQ2 applied to the output shaft 4 by a second blow in which the hammer 33 applies an impact force to the anvil 34 following the first blow. The second increment is the increase in the rotation angle of the output shaft 4 from when the first torque TQ1 is applied to when the second torque TQ2 is applied.

[0097] According to this aspect, it is possible to prevent the time until the tightening torque reaches the target value from becoming long, and it is possible to improve the efficiency of the work.

[0098] The impact tool (1) of the second aspect is the same as that of the first aspect, and further includes a determination unit (84). The determination unit (84) determines a joint rate based on the second increase and preset setting data. The setting data is data indicating a correspondence relationship between a plurality of increase ranges and a plurality of candidate rates respectively corresponding to the plurality of increase ranges. The determination unit (84) selects a corresponding increase range, which is an increase range that includes the second increase, from the plurality of increase ranges, and determines a candidate rate corresponding to the corresponding increase range from the plurality of candidate rates as the joint rate.

[0099] According to this embodiment, the determination unit (84) does not need to calculate the joint rate each time, and therefore the processing load on the determination unit (84) can be reduced.

[0100] The impact tool (1) of the third aspect is the impact tool of the first or second aspect, further comprising an angle measuring unit (6) that measures a rotation angle of the output shaft (4).

[0101] According to this aspect, it is possible to improve the accuracy of calculating the joint rate.

[0102] The impact tool (1) of the fourth aspect, in any of the first to third aspects, further includes an angle calculation unit (83) that calculates a second increase amount based on the period (Ti) from when the first torque (TQ1) is applied to the output shaft (4) to when the second torque (TQ2) is applied.

[0103] According to this embodiment, the process of calculating the second increase amount can be simplified.

[0104] The impact tool (1) of a fifth aspect is any one of the first to fourth aspects, further including an acquisition unit (88) that acquires designation information for designating a joint rate from an outside. The motor control unit (81) controls the rotation speed of the motor (2) in accordance with the joint rate designated by the designation information.

[0105] According to this embodiment, the rotation speed of the motor (2) can be controlled externally.

[0106] The impact tool (1) of the sixth aspect, in any one of the first to fifth aspects, further includes a determination unit (84) that determines the joint rate using a trained model that has been machine-learned to use the second increase as an input and output the joint rate.

[0107] According to this aspect, it is possible to improve the accuracy of calculating the joint rate.

[0108] The impact tool (1) of the seventh aspect is the sixth aspect, further including an update unit (87) that updates the trained model used in the determination unit (84) based on external information.

[0109] According to this aspect, it is possible to improve the accuracy of calculating the joint rate using the trained model.

[0110] The impact tool (1) of an eighth aspect is any one of the first to seventh aspects, in which the motor control section (81) controls the motor (2) so that the rotation speed increases as the joint rate decreases.

[0111] According to this aspect, it is possible to prevent the time required for the tightening torque to reach the target value from becoming longer as the joint rate becomes smaller, thereby improving work efficiency.

[0112] In the impact tool (1) of a ninth aspect, in any one of the first to eighth aspects, the motor control section (81) controls the motor (2) so that the rotation speed changes stepwise in accordance with the joint rate.

[0113] According to this aspect, it is possible to prevent the time until the tightening torque reaches the target value from becoming long, and it is possible to improve the efficiency of the work.

[0114] The control method of the tenth aspect is a control method for an impact tool (1) including a motor (2), a hammer (33) that rotates by receiving power from the motor (2), an anvil (34) that rotates by receiving an impact force from the hammer (33) in the rotation direction of the hammer (33), and an output shaft (4) that is configured to hold the tool bit (11) and rotates together with the anvil (34). The control method includes a motor control step of controlling the rotation speed of the motor (2) according to a joint rate. The joint rate is a value obtained by dividing a first increment by a second increment. The first increment is the difference between a first torque TQ1 applied to the output shaft (4) by a first blow in which the hammer (33) applies an impact force to the anvil (34) and a second torque TQ2 applied to the output shaft (4) by a second blow in which the hammer (33) applies an impact force to the anvil (34) following the first blow. The second increment is an increment in the rotation angle of the output shaft (4) from when the first torque (TQ1) is applied until when the second torque (TQ2) is applied.

[0115] According to this aspect, it is possible to prevent the time until the tightening torque reaches the target value from becoming long, and it is possible to improve the efficiency of the work.

[0116] A program according to an eleventh aspect is a program for causing one or more processors to execute the control method according to the tenth aspect.

[0117] According to this aspect, it is possible to prevent the time until the tightening torque reaches the target value from becoming long, and it is possible to improve the efficiency of the work.

[0118] It should be noted that the second to ninth aspects are not essential configurations for the impact tool (1) and may be omitted as appropriate. [Explanation of symbols]

[0119] 1 Impact tool 2 Motors 4 Output Shaft 6 Angle measurement section 11 Tip tools 33 Hammer 34 Anvil 81 Motor control unit 83 Angle calculation unit 84 Decision Section 87 Update section 88 Acquisition Department TQ1 1st torque TQ2 2nd Torque

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 bit and rotate with the anvil; a motor control unit that controls the rotation speed of the motor in response to a joint rate that is a value obtained by dividing a first increase amount, which is a difference between a first torque applied to the output shaft by a first blow in which the hammer applies the impact force to the anvil, and a second torque applied to the output shaft by a second blow in which the hammer applies the impact force to the anvil following the first blow, by a second increase amount, which is an increase amount of a rotation angle of the output shaft from when the first torque is applied to when the second torque is applied. Impact tool.

2. A determination unit is further provided, The determination unit determines the joint rate based on the second increase amount and preset setting data, the setting data is data indicating a correspondence relationship between a plurality of increase amount ranges and a plurality of candidate rates respectively corresponding to the plurality of increase amount ranges, The determination unit is selecting a corresponding increment range that includes the second increment from among the plurality of increment ranges; determining, as the joint rate, the candidate rate corresponding to the corresponding increase amount range among the plurality of candidate rates; 2. The impact tool according to claim 1.

3. Further comprising an angle measuring unit for measuring the rotation angle of the output shaft. An impact tool according to claim 1 or 2.

4. an angle calculation unit that calculates the second increase amount based on a period from when the first torque is applied to the output shaft to when the second torque is applied to the output shaft, An impact tool according to claim 1 or 2.

5. An acquisition unit that acquires designation information for designating the joint rate from an external source, The motor control unit controls the rotation speed of the motor in accordance with the joint rate designated by the designation information. An impact tool according to claim 1 or 2.

6. A determination unit that determines the joint rate using a trained model that is machine-learned to input the second increase amount and output the joint rate, An impact tool according to claim 1 or 2.

7. Further comprising an update unit that updates the trained model used by the determination unit based on external information.

7. An impact tool according to claim 6.

8. the motor control unit controls the motor so that the rotation speed increases as the joint rate decreases. An impact tool according to claim 1 or 2.

9. the motor control unit controls the motor so that the rotation speed changes stepwise in accordance with the joint rate. An impact tool according to claim 1 or 2.

10. A control method for an impact tool including 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 a rotational direction of the hammer, and an output shaft that is configured to hold a tool bit and rotates together with the anvil, a motor control step of controlling a rotation speed of the motor in response to a joint rate obtained by dividing a first increment, which is a difference between a first torque applied to the output shaft by a first blow in which the hammer applies the impact force to the anvil, and a second torque applied to the output shaft by a second blow in which the hammer applies the impact force to the anvil following the first blow, by a second increment, which is an increment in a rotation angle of the output shaft from when the first torque is applied to when the second torque is applied. Control methods.

11. A program for causing one or more processors to execute the control method according to claim 10.

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