Electric power tool, electric power tool system, control method, and program

Abstract

To determine presence / absence of abnormality in thread fastening in an electric power tool performing an impact operation.SOLUTION: An electric power tool 10 includes a motor, a hammer, an anvil, an output axis, an impact detection part 112, a motor control part 115, and a storage part 117. The motor control part 115 performs thread fastening of a screw by predetermined control to the motor when receiving a prescribed command from external equipment 50a. The motor control part 115 executes a determination processing where the presence / absence of abnormality in thread fastening is determined on the basis of the relation between the rotation angle of the motor and the detection result of the presence / absence of the impact operation in the impact detection part 112. The predetermined control comprises stopping the motor when it is determined that the thread fastening has abnormality, as a result of the determination processing.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure generally relates to a power tool, a power tool system, a control method, and a program. More specifically, the present disclosure relates to a power tool that performs an impact operation, a power tool system including the power tool, a control method for a power tool that performs an impact operation, and a program for executing the control method. [Background technology]

[0002] The automatic screw tightening device (electric tool) described in Patent Document 1 has a driver tool that engages with a screw, a reciprocating means, and a control means. The reciprocating means supports the driver tool so that it can be moved back and forth. The control means compares the movement distance of the driver tool with a preset distance to determine whether screw tightening is being performed normally or not, and stops screw tightening if it determines that an abnormality has occurred. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-031888 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the configuration of the automatic screw tightening device described in Patent Document 1 is applied to a power tool that performs an impact operation, it may be difficult to determine whether or not there is an abnormality in the screw tightening.

[0005] An object of the present disclosure is to provide a power tool, a power tool system, a control method, and a program that can accurately determine whether or not there is an abnormality in screw tightening in a power tool that performs an impact operation. [Means for solving the problem]

[0006] A power tool according to one aspect of the present disclosure is a power tool for tightening a screw. The power tool includes a motor, a hammer, an anvil, an output shaft, an impact detection unit, a motor control unit, and a memory 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 transmits torque to the screw, and rotates together with the anvil. The impact detection unit detects the presence or absence of an impact operation, which is an operation of the hammer applying the impact force to the anvil. The motor control unit controls the operation of the motor based on a command from an external device outside the power tool. The memory unit stores information for the motor control unit to perform a predetermined control on the motor. When the motor control unit receives a predetermined command from the external device, the motor control unit tightens the screw by the predetermined control on the motor. The motor control unit executes a determination process to determine the presence or absence of an abnormality in the screw tightening based on the relationship between the rotation angle of the motor and the detection result of the impact detection unit indicating the presence or absence of the impact motion. The default control includes stopping the motor when it is determined as a result of the determination process that there is an abnormality in the screw tightening.

[0007] According to one aspect of the present disclosure, there is provided a power tool system including the power tool and a robot arm, the robot arm holding the power tool and controlling a position and attitude of the power tool.

[0008] According to another aspect of the present disclosure, there is provided a power tool system including the power tool and a robot, the robot being the external device that issues a command to the motor control unit, the robot including a robot arm that holds the power tool and controls a position and attitude of the power tool.

[0009] A control method according to one aspect of the present disclosure is a control method for a power tool for tightening a screw. The power tool includes a motor, a hammer, an anvil, an output shaft, and an impact detection 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 transmits torque to the screw, and rotates together with the anvil. The impact detection unit detects the presence or absence of an impact motion, which is an operation of the hammer applying the impact force to the anvil. The control method is executed by a computer system. The control method includes, when a predetermined command is received from an external device outside the power tool, tightening the screw by a default control of the motor, and executing a determination process for determining the presence or absence of an abnormality in the tightening of the screw based on a relationship between a rotation angle of the motor and a detection result of the presence or absence of the impact motion by the impact detection unit. The default control includes stopping the motor when it is determined as a result of the determination process that there is an abnormality in the tightening of the screw.

[0010] A program according to one aspect of the present disclosure is a program for causing one or more processors of the computer system to execute the control method. Effect of the Invention

[0011] The present disclosure has the advantage of being able to accurately determine whether or not there is an abnormality in screw tightening in a power tool that performs an impact operation. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram of a power tool system according to an embodiment. [Diagram 2] FIG. 2 is a perspective view of a main part of the electric power tool system. [Diagram 3] FIG. 3 is a front view showing the above electric power tool system in an operating state. [Figure 4]FIG. 4 is a schematic diagram showing an internal structure of the power tool of the power tool system. [Diagram 5] FIG. 5 is an explanatory diagram illustrating an example of the operation of the power tool system. [Figure 6] 6A to 6F are schematic diagrams illustrating a screw tightening operation performed by the power tool system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] (Embodiment) The power tool 10, the power tool system 100, the control method, and the program according to the embodiment will be described below with reference to the drawings. However, the embodiment described below is merely one of various embodiments of the present disclosure. The embodiment described below can be modified in various ways depending on the design, etc., as long as the object of the present disclosure can be achieved. Also, each figure described in the embodiment described below is a schematic diagram, and the size and thickness ratios of each component in the figure do not necessarily reflect the actual dimensional ratios.

[0014] (1) Overview Fig. 1 is a schematic block diagram of a power tool system 100 including a power tool 10 according to the present embodiment. Fig. 2 is an external perspective view showing an installation state of a robot 50 holding the power tool 10. Fig. 3 is a front view showing a state in which the power tool 10 performs a screw tightening operation. Fig. 4 is a schematic diagram showing the internal structure of the power tool 10.

[0015] The electric power tool 10 is for tightening a screw B1. The electric power tool 10 includes a motor M1, a hammer 74, an anvil 75, an output shaft 22, an impact detection unit 112, a motor control unit 115, and a memory unit 117. The hammer 74 rotates by receiving power from the motor M1. The anvil 75 rotates by receiving an impact force from the hammer 74 in the rotation direction of the hammer 74. The output shaft 22 is configured to hold a tip tool 23 that transmits torque to the screw B1, and rotates together with the anvil 75. The impact detection unit 112 detects the presence or absence of an impact operation, which is an operation in which the hammer 74 applies an impact force to the anvil 75. The motor control unit 115 controls the operation of the motor M1 based on a command from an external device 50a outside the electric power tool 10. The memory unit 117 stores information for the motor control unit 115 to perform a predetermined control of the motor M1. When the motor control unit 115 receives a predetermined command from the external device 50a, it tightens the screw B1 by a default control of the motor M1. The motor control unit 115 executes a determination process to determine the presence or absence of an abnormality in the screw tightening based on the relationship between the rotation angle of the motor M1 and the detection result of the impact detection unit 112 as to the presence or absence of an impact operation. Here, the rotation angle may be a set value or a measured value. The default control includes stopping the motor M1 when it is determined as a result of the determination process that there is an abnormality in the screw tightening.

[0016] According to the above configuration, the power tool 10 performing the impact operation can accurately determine whether or not there is an abnormality in the screw tightening, and if there is an abnormality, the motor M1 can be stopped. This improves the accuracy of the response to the abnormality.

[0017] Here, as a comparative example to be contrasted with the power tool 10 of this embodiment, a power tool that determines whether or not there is an abnormality in screw tightening based on the characteristics of the current flowing through the motor M1 during impact operation is assumed. When an abnormality such as galling (burning) or oblique tightening occurs in the screw B1, the screw B1 becomes difficult to move, and in this case, the characteristics of the current flowing through the motor M1 during impact operation may be similar to the characteristics when the screw B1 is normally seated and difficult to move. Therefore, with the power tool of the comparative example, it may be difficult to accurately determine whether or not there is an abnormality in screw tightening.

[0018] In contrast, in the power tool 10 of this embodiment, the motor control unit 115 determines whether or not there is an abnormality in the screw tightening based on the relationship between the rotation angle of the motor M1 and the detection result of the presence or absence of impact operation in the impact detection unit 112, so that the presence or absence of an abnormality in the screw tightening can be determined with high accuracy.

[0019] Moreover, the power tool system 100 of this embodiment includes the power tool 10 and a robot 50. The robot 50 is an external device 50a that issues commands to the motor control unit 115. The robot 50 includes a robot arm 51. The robot arm 51 holds the power tool 10 and controls the position and posture of the power tool 10. Therefore, the power tool system 100 can automatically perform a screw tightening operation and accurately determine whether or not there is an abnormality in the screw tightening.

[0020] The control method of this embodiment is a control method of the power tool 10 for tightening the screw B1. The power tool 10 includes a motor M1, a hammer 74, an anvil 75, an output shaft 22, and an impact detection unit 112. The hammer 74 rotates by receiving power from the motor M1. The anvil 75 rotates by receiving an impact force from the hammer 74 in the rotation direction of the hammer 74. The output shaft 22 is configured to hold a tool tip 23 that transmits torque to the screw B1, and rotates together with the anvil 75. The impact detection unit 112 detects the presence or absence of an impact operation, which is an operation in which the hammer 74 applies an impact force to the anvil 75. The control method is executed by a computer system. The control method includes, upon receiving a predetermined command from an external device 50a outside the power tool 10, tightening the screw B1 by a preset control of the motor M1, and executing a determination process for determining the presence or absence of an abnormality in the screw tightening based on the relationship between the rotation angle of the motor M1 and the detection result of the presence or absence of an impact operation by the impact detection unit 112. The preset control includes stopping the motor M1 when it is determined as a result of the determination process that there is an abnormality in the screw tightening.

[0021] The above control method can be embodied in a program. The program of this embodiment is a program for causing one or more processors of a computer system to execute the above control method. The program may be recorded in a non-transitory recording medium readable by the computer system.

[0022] (2)Details Hereinafter, the power tool 10 and the power tool system 100 according to this embodiment will be described in detail with reference to the drawings.

[0023] (2.1) Structure As described above, the power tool system 100 includes the power tool 10 and the robot 50. The power tool system 100 of this embodiment further includes a receiver 30, a centralized management unit 40, and a control device 60, as shown in FIG.

[0024] Here, the robot 50 is, for example, an industrial robot installed in a factory. The power tool 10 is a tool held by a robot arm 51 (see FIG. 2) of the robot 50, and is therefore a so-called end effector. The power tool 10 is a tool that performs screw tightening work to tighten a screw B1 (fastening member) such as a bolt or a nut on a work object, for example. Since the power tool 10 is held by the multi-joint type robot arm 51, it can perform screw tightening work on the work object from any direction.

[0025] The power tool 10, the robot 50, the receiver 30, the centralized control unit 40, and the control device 60 included in the power tool system 100 will be described in detail below with reference to the drawings.

[0026] (2.1.1) Robots The robot 50 is, for example, an industrial robot that performs a screw tightening operation to tighten a screw B1 into a workpiece W1 that is a work target (see FIG. 2).

[0027] As shown in Fig. 2, the robot 50 is installed on a workbench 500, and performs a screw tightening operation on a workpiece W1 placed on the upper surface of the workbench 500. The robot 50 has a multi-joint robot arm 51. The robot arm 51 has, for example, six degrees of freedom. The robot arm 51 has six arms 511 to 516, which are rotatably connected via joints. A motor is incorporated in the joints, and the arms 511 to 516 are configured to rotate individually by rotating the motor.

[0028] As shown in FIG. 1, the robot 50 includes a control unit 52, a communication unit 53, a posture detection unit 54, a load detection unit 55, an arm driving unit 56, and an operation unit 57.

[0029] The control unit 52 performs overall control of the robot 50. The control unit 52 is mainly composed of a computer system having one or more processors and a memory. The functions of the control unit 52 are 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 recorded on a non-transitory recording medium such as a memory card and provided.

[0030] The communication unit 53 is capable of communicating with the second communication unit 16 of the power tool 10 in a wired communication manner or a wireless communication manner.

[0031] The attitude detection unit 54 includes, for example, a plurality of rotary encoders that detect the rotation angles of the arms 511 to 516 of the robot arm 51, and a plurality of angular velocity sensors that detect the angular velocities of the arms 511 to 516. The attitude detection unit 54 detects the position, orientation, etc. of the arm 516 at the tip based on, for example, the detection results of the plurality of rotary encoders and the detection results of the plurality of angular velocity sensors.

[0032] Load detection unit 55 includes, for example, a force sensor attached to tip arm 516 and detects the magnitude of the load applied to tip arm 516 or the impact force applied to tip arm 516 .

[0033] The arm driving unit 56 includes a plurality of motors for rotating the arms 511 to 516, respectively, and a plurality of driver circuits for driving the plurality of motors, respectively. The arm driving unit 56 rotates the plurality of motors based on a control command input from the control unit 52, thereby moving the arm 516 at the tip to a position specified by the control command.

[0034] The operation unit 57 includes an interface device such as an operation button or a touch panel provided on the robot 50. The operation unit 57 receives operation information input by a user and outputs it to the control unit 52. The control unit 52 outputs a command to the power tool 10 via the communication unit 53 in accordance with the operation information.

[0035] (2.1.2) Control equipment The control device 60 controls the operation of the robot 50. The control device 60 is installed, for example, in a factory where the robot 50 to be controlled is installed.

[0036] As shown in FIG. 1, the control device 60 includes a control unit 61, a communication unit 62, and a storage unit 63.

[0037] The communication unit 62 is capable of communicating with the communication unit 53 of the robot 50 and the communication unit 42 of the centralized control unit 40 via wired communication or wireless communication.

[0038] The storage unit 63 stores a work position where the robot 50 works on a work target, and posture information related to the posture of the robot arm 51 at the work position, etc. The posture information related to the posture of the robot arm 51 includes, for example, information such as the position and orientation of the arm 516 to which the power tool 10 is attached. When there are multiple work positions for the workpiece W1 where the robot 50 works, the storage unit 63 stores posture information related to the posture of the robot arm 51 at each of the multiple work positions. When the robot 50 works on multiple types of workpieces W1, posture information related to the posture of the robot arm 51 may be stored for each of the multiple types of workpieces W1.

[0039] The control unit 61 controls the operation of the robot 50 to cause the power tool 10 held by the robot 50 to perform a task on a work object. Based on the task position and the posture information of the robot arm 51 at the task position stored in the memory unit 63, the control unit 61 moves the power tool 10 to the task position and causes the power tool 10 to perform a task on a work object.

[0040] (2.1.3) Power tools 1, the power tool 10 includes a processing unit 11, an inclination sensor 12, a torque sensor 13, a tool driving unit 14, a first communication unit 15, a second communication unit 16, a notification unit 17, a power supply unit 18, and a current sensor 19. The tool driving unit 14 includes a motor M1 (see FIG. 4).

[0041] The electric power tool 10 includes a tool body 21 that houses a processing unit 11, an inclination sensor 12, a torque sensor 13, a tool driving unit 14, a first communication unit 15, a second communication unit 16, an alarm unit 17, a power supply unit 18, a current sensor 19, etc. The tool body 21 is formed in a long and thin rectangular tube shape. The tool body 21 is attached to an arm 516 at the tip of a robot arm 51 of a robot 50. An output shaft 22 protrudes from one end face in the longitudinal direction of the tool body 21. The output shaft 22 is held in a rotatable state relative to the tool body 21.

[0042] The first communication unit 15 is capable of communicating with a first communication unit 32 of the receiver 30 via wireless communication.

[0043] The second communication unit 16 is capable of communicating with the communication unit 53 of the robot 50 via a wired communication method or a wireless communication method.

[0044] The processing unit 11 mainly comprises a computer system having one or more processors and a memory. The functions of the processing unit 11 are 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.

[0045] The processing unit 11 has the functions of a direction detection unit 111, an impact detection unit 112, a notification unit 113, a torque calculation unit 114, a motor control unit 115, and a current detection unit 116. Note that the direction detection unit 111, the impact detection unit 112, the torque calculation unit 114, the motor control unit 115, and the current detection unit 116 merely indicate functions realized by the processing unit 11, and do not necessarily indicate actual configurations.

[0046] The processing unit 11 also includes a storage unit 117. The storage unit 117 includes the memory of the computer system.

[0047] The tilt sensor 12 includes, for example, a three-axis acceleration sensor housed inside the tool body 21. The tilt sensor 12 detects the gravitational acceleration acting on the tool body 21, thereby being able to detect the tilt angle of the tool body 21 with respect to the direction of gravity.

[0048] For example, when the robot arm 51 moves and the output shaft 22 moves to a working position, the direction detection unit 111 detects the orientation of the output shaft 22 based on the detection result of the tilt sensor 12 .

[0049] The current sensor 19 outputs a detection signal corresponding to the magnitude of the current flowing through the motor M1. The current detection unit 116 detects (measures) the current flowing through the motor M1 based on the detection signal output from the current sensor 19.

[0050] The impact detection unit 112 detects the presence or absence of an impact motion based on the current detected by the current detection unit 116. For example, the impact detection unit 112 determines that an impact motion is occurring when the current detected by the current detection unit 116 changes from a state below the threshold to a state above the threshold. Then, for example, the impact detection unit 112 determines that an impact motion is not occurring when the state in which the current detected by the current detection unit 116 remains below the threshold for a predetermined period of time or more.

[0051] The motor control unit 115 determines a command rotation speed based on information stored in the storage unit 117, and outputs a control command including information indicating the command rotation speed to the tool driving unit 14. The tool driving unit 14 controls the motor M1 so that the rotation speed of the motor M1 approaches the command rotation speed.

[0052] More specifically, information indicating a change in the command rotation speed according to the elapsed time since the motor M1 starts rotating is stored in the storage unit 117. Fig. 5 shows an example of the change in the command rotation speed over time stored in the storage unit 117. The rotation speed of the motor M1 is controlled according to such information.

[0053] Furthermore, the motor control unit 115 executes a determination process to determine whether or not there is an abnormality in the screw tightening. If the motor control unit 115 determines as a result of the determination process that there is an abnormality in the screw tightening, it stops the motor M1.

[0054] The notification unit 113 performs a process of notifying the result of the determination process of the motor control unit 115. The notification unit 113 outputs an announcement command according to the result of the determination process to the notification unit 17, and causes the notification unit 17 to perform an announcement operation.

[0055] The alarm unit 17 performs an alarm operation by sound or light in response to an alarm command from the notification unit 113. The alarm unit 17 includes, for example, a buzzer 171 housed inside the tool body 21 and an indicator light 172 arranged in a visible state on the surface of the tool body 21. The indicator light 172 includes, for example, an LED capable of emitting two colors, red and green. The notification unit 113 changes the manner of the sound emitted by the buzzer 171 and the light color of the indicator light 172 depending on, for example, whether there is an abnormality in the screw tightening or not.

[0056] For example, if there is no abnormality in the screw tightening, the notification unit 113 does not make the buzzer 171 emit a sound, and if there is an abnormality in the screw tightening, the notification unit 113 makes the buzzer 171 emit a sound. In this way, in this embodiment, the notification unit 113 notifies the result of the determination process by sound, and the operator can grasp the result of the determination process by hearing.

[0057] Furthermore, for example, when there is no abnormality in the screw tightening, the notification unit 113 lights the indicator light 172 in green, and when there is an abnormality in the screw tightening, the notification unit 113 lights the indicator light 172 in red. In this way, the notification unit 113 notifies the operator of the result of the determination process with light, and the operator can visually grasp the result of the determination process.

[0058] The torque sensor 13 detects the torque applied to the output shaft 22, for example, when the power tool 10 performs a screwing operation of the screw B1.

[0059] The torque calculation unit 114 calculates the tightening torque of the screw B1 by the tool bit 23 based on the detection result of the torque sensor 13.

[0060] The power supply unit 18 receives power from an external power supply 90 such as a commercial AC power supply, and generates an operating voltage for the power tool 10 .

[0061] The tool driving unit 14 includes a motor M1 (see FIG. 4) housed in the tool body 21, a driving circuit for driving the motor M1, and a transmission mechanism 70 (see FIG. 4) for transmitting the rotational force of the motor M1 to the output shaft 22. The tool driving unit 14 rotates the motor M1 in response to a control command from the motor control unit 115, thereby rotating the tool tip 23 attached to the output shaft 22.

[0062] The transmission mechanism 70 will be described with reference to Fig. 4. The transmission mechanism 70 transmits the rotational power of the motor M1 to the output shaft 22 to rotate the output shaft 22. In this embodiment, the side on which the output shaft 22 is located as viewed from the motor M1 is defined as the front, and the side on which the motor M1 is located as viewed from the output shaft 22 is defined as the rear. However, these definitions are not intended to limit the direction in which the power tool 10 is used.

[0063] The transmission mechanism 70 includes a transmission 71, a drive shaft 72, a spring 73, a hammer 74, and an anvil 75.

[0064] The transmission 71 includes, for example, a planetary gear mechanism. The transmission 71 is interposed between the motor M1 and the drive shaft 72. The transmission 71 reduces the rotational power of the motor M1 at a predetermined reduction ratio and outputs the reduced power as rotation of the drive shaft 72.

[0065] The hammer 74 is attached to the drive shaft 72 via a cam mechanism. The anvil 75 rotates by receiving a rotational force from the hammer 74. The spring 73 is a compression coil spring. The spring 73 pushes the hammer 74 toward the anvil 75 (forward). The anvil 75 is formed integrally with the output shaft 22. Note that the anvil 75 may be formed separately from the output shaft 22 and fixed to the output shaft 22.

[0066] When the output shaft 22 is not subjected to a load (torque) of a predetermined magnitude or more, the drive shaft 72 and the hammer 74 connected by the cam mechanism rotate together, and further the hammer 74 and the anvil 75 rotate together, so that the output shaft 22 formed integrally with the anvil 75 rotates. On the other hand, when the output shaft 22 is subjected to a load of a predetermined magnitude or more, the hammer 74 moves backward against the spring 73 while being restricted by the cam mechanism (i.e., moves away from the anvil 75), and when the connection between the hammer 74 and the anvil 75 is released, the hammer 74 moves forward while rotating, applying an impact force in the rotational direction to the anvil 75 and rotating the output shaft 22. In this manner, the impact operation in which the hammer 74 and the anvil 75 collide with each other and transmit the impact force is repeated.

[0067] 3, a holder 24 is attached to the output shaft 22, and a tool tip 23 is attached to the holder 24 via a coil spring 25. The tool tip 23 is a socket attached to the outer edge of the screw B1.

[0068] (2.1.4) Receiver The receiver 30 is installed in a location where wireless communication with the first communication unit 15 of the power tool 10 is possible. The receiver 30 relays communication between the power tool 10 and the centralized control unit 40.

[0069] The receiver 30 includes a control unit 31, a first communication unit 32, and a second communication unit 33.

[0070] The first communication unit 32 is capable of communicating with the first communication unit 15 of the power tool 10 via wireless communication.

[0071] The second communication unit 33 is capable of communicating with the communication unit 42 of the centralized control unit 40 via a network NT such as the Internet or a LAN.

[0072] The control unit 31 mainly comprises a computer system having one or more processors and a memory. The functions of the control unit 31 are 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.

[0073] When the first communication unit 32 receives a signal from the power tool 10, the control unit 31 causes the second communication unit 33 to transmit the signal from the power tool 10 to the centralized management unit 40. When the second communication unit 33 receives a signal from the centralized management unit 40, the control unit 31 causes the first communication unit 32 to transmit the signal from the centralized management unit 40 to the power tool 10.

[0074] (2.1.5) Centralized management department The centralized management unit 40 manages the power tool 10. Here, the management of the power tool 10 includes at least one of managing the work content of the work using the power tool 10 and managing the operating state of the power tool 10. The management of the work content includes at least one of setting a tightening torque setting value for the power tool 10 and acquiring work result information related to the work result of the work performed by the power tool 10 on the work object (e.g., the actual tightening torque value, the number of rotations during the screw tightening work, and the presence or absence of an abnormality in the screw tightening). The management of the operating state of the power tool 10 includes at least one of measuring the operating time of the power tool 10, notifying the maintenance timing of the power tool 10, and accumulating an error signal output by the power tool 10 to notify an abnormality.

[0075] As shown in FIG. 1, the centralized management unit 40 includes a control unit 41, a communication unit 42, and a storage unit 43.

[0076] The communication unit 42 is configured to be able to communicate with the second communication unit 33 of the receiver 30 and the communication unit 62 of the control device 60 by wired communication or wireless communication.

[0077] The storage unit 43 includes an internal memory such as a random access memory (RAM), a read-only memory (ROM) or an electrically erasable and programmable read-only memory (EEPROM), and an external storage device such as a hard disk drive or an SSD. The storage unit 43 stores setting information such as a setting value of the fastening torque to be set in the power tool 10, work result information obtained from the power tool 10, error signals obtained from the power tool 10, and the like.

[0078] The control unit 41 mainly comprises a computer system having one or more processors and a memory. The functions of the control unit 41 are 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.

[0079] The control unit 41 causes the communication unit 42 to transmit the setting information stored in the storage unit 43 to the power tool 10 via the receiver 30, and sets the setting information in the power tool 10. In addition, when the communication unit 42 receives work result information from the power tool 10, the control unit 41 causes the storage unit 43 to store the work result information received by the communication unit 42.

[0080] (2.2) Screw tightening abnormality Here, first, an example of the structure of the screw B1 will be described, and then various examples of screw tightening abnormalities will be described.

[0081] As shown in Fig. 6A, the screw B1 includes a head B11 and a threaded portion B12. The head B11 has a disk-like shape. The threaded portion B12 has a cylindrical shape. The threaded portion B12 protrudes from the head B11. The diameter of the threaded portion B12 is smaller than the diameter of the head B11.

[0082] "Seizing" in which the threaded portion B12 melts against the inner surface of the threaded hole W10 in the workpiece W1 is an example of an abnormality in screw tightening.

[0083] “Diagonal tightening”, where the screw B1 is screwed in at an angle, is an example of an abnormal screw tightening.

[0084] When the screw hole W10 has a bottom surface, bottoming out, in which the tip of the threaded portion B12 comes into contact with the bottom surface before the screw B1 is seated, is an example of an abnormality in screw tightening.

[0085] An example of a screw tightening abnormality is when the diameter of the threaded portion B12 is excessively large compared to the diameter of the screw hole W10.

[0086] An example of a screw tightening abnormality is when the diameter of the threaded portion B12 is too small compared to the diameter of the screw hole W10.

[0087] An example of a screw tightening abnormality is when the inner diameter of the socket-shaped tool bit 23 is excessively large compared to the outer diameter of the head B11.

[0088] An example of a screw tightening abnormality is when the pitch (the distance between the threads) of the screw portion B12 does not correspond to the pitch of the screw hole W10.

[0089] The damage to the screw B1 is an example of an abnormality in the screw tightening.

[0090] The absence of screw B1 (forgotten to set) is an example of a screw tightening abnormality.

[0091] The absence of workpiece W1 (forgetting to set it) is an example of a screw tightening abnormality.

[0092] (2.3) Operation Description The operation of the power tool system 100 of this embodiment will be described with reference to Fig. 5, Fig. 6A to Fig. 6F, etc. Note that, although star-shaped marks are illustrated in Fig. 6B and Fig. 6C, these marks merely indicate that an impact operation is being performed, and do not represent an actually existing configuration.

[0093] As described above, when the motor control unit 115 receives a predetermined command from the external device 50a (robot 50), it performs a predetermined control on the motor M1 to tighten the screw B1. More specifically, a signal including a first signal and a second signal is output from the external device 50a to the motor control unit 115.

[0094] The first signal is a signal that commands whether to rotate or stop the motor M1. The first signal is a high-level signal or a low-level signal. When the first signal acquired from the external device 50a is a high-level signal, the motor control unit 115 rotates the motor M1. When the first signal acquired from the external device 50a is a low-level signal, the motor control unit 115 stops the motor M1.

[0095] The second signal is a signal that instructs whether to tighten or loosen the screw B1. The second signal is a high-level signal or a low-level signal. When the second signal acquired from the external device 50a is a high-level signal, the motor control unit 115 controls the motor M1 to tighten the screw B1. When the second signal acquired from the external device 50a is a low-level signal, the motor control unit 115 controls the motor M1 to loosen the screw B1.

[0096] The motor control unit 115 determines the control according to a combination of the first signal and the second signal acquired from the external device 50a. When the first signal is a high level signal and the second signal is a high level signal, the motor control unit 115 performs a predetermined control on the motor M1. When the first signal is a high level signal and the second signal is a low level signal, the motor control unit 115 causes the motor M1 to perform a reverse operation. When the first signal is a low level signal, the motor control unit 115 stops the motor M1.

[0097] In this way, the signal output from the external device 50a to the motor control unit 115 is a simple signal, and detailed control of the motor M1 is determined on the power tool 10 side.

[0098] The default control will be described below. The default control is a control for tightening the screw B1. The motor control unit 115 also executes a determination process to determine whether or not there is an abnormality in the tightening of the screw, and if it is determined as a result of the determination process that there is an abnormality in the tightening of the screw, it stops the motor M1. Fig. 5 shows the change over time in the command rotation speed when it is not determined as a result of the determination process that there is an abnormality in the tightening of the screw.

[0099] The motor control unit 115 controls the motor M1 to perform forward and reverse rotation as a default control. The forward rotation is an operation to rotate in a direction to tighten the screw B1. The reverse rotation is an operation to rotate in the opposite direction to the forward rotation. In other words, the reverse rotation is an operation to rotate in a direction to loosen the screw B1 (the opposite direction to the direction to tighten the screw B1). If the screw B1 is a right-handed screw, the forward rotation is a right rotation and the reverse rotation is a left rotation.

[0100] As shown in Figure 5, the default control can be expressed as the change in the command speed over time. When the command speed is a positive value, the motor M1 rotates forward, and when the command speed is a negative value, the motor M1 rotates reverse. When the command speed is 0, the motor M1 stops.

[0101] Periods T1, T2, ..., T8 are set in chronological order from the earliest time. In each of the periods T1 to T8, the command rotation speed is a positive value or a negative value. In addition, a brake period is set between each period. The brake period is a period in which the command rotation speed is set to 0.

[0102] When the default control is started, the motor control unit 115 first causes the motor M1 to perform a reverse rotation operation during the period T1 in order to reduce the possibility of the screw B1 being obliquely fastened. In other words, the motor control unit 115 sets the command number of rotations to a negative value during the period T1.

[0103] Next, the motor control unit 115 sets the command speed to a positive value in period T2. Furthermore, the motor control unit 115 sets the command speed to a positive value in period T3. The command speed in period T2 is a smaller value than the command speed in period T3, and this causes the motor M1 to soft start in period T2.

[0104] The motor control unit 115 sets the command rotation speed to a positive value in periods T4, T7, and T8, and sets the command rotation speed to a negative value in periods T5 and T6.

[0105] 6A to 6F show examples of the relationship between the screw B1 and the workpiece W1 during periods T3 to T8, respectively.

[0106] 6A, the power tool 10 temporarily tightens the screw B1. That is, the power tool 10 partially inserts the screw portion B12 into the screw hole W10 of the workpiece W1. For example, the motor control unit 115 rotates the motor M1 forward by a certain rotation angle.

[0107] During the period T4, the power tool 10 performs an impact operation to tighten the screw B1, as shown in Fig. 6B. For example, the motor control unit 115 rotates the motor M1 in the normal direction until the number of impact operations reaches a certain number.

[0108] During a period T5, the power tool 10 loosens the screw B1 as shown in Fig. 6C. For example, the motor control unit 115 rotates the motor M1 in the reverse direction by a certain rotation angle.

[0109] During a period T6, the power tool 10 further loosens the screw B1 as shown in Fig. 6D. For example, the motor control unit 115 causes the motor M1 to rotate in the reverse direction by a certain rotation angle.

[0110] During the period T7, the power tool 10 temporarily tightens the screw B1 as shown in Fig. 6E. For example, the motor control unit 115 rotates the motor M1 in the forward direction by a certain rotation angle.

[0111] During period T8, the power tool 10 tightens the screw B1 as shown in Fig. 6F. For example, the motor control unit 115 rotates the motor M1 in the forward direction by a certain rotation angle. The tightening during period T8 is the final tightening (final tightening).

[0112] In this way, the default control includes a first control and a second control. In the first control, the motor M1 is caused to alternately perform a forward rotation operation in which it rotates in a direction in which the screw B1 is tightened, and a reverse rotation operation in which it rotates in a direction opposite to the forward rotation operation. In the second control, if it is determined as a result of the determination process that there is no abnormality in the screw tightening in the first control, the motor M1 is caused to perform a forward rotation operation to tighten the screw B1. The control in the periods T3 to T7 is the first control, and the control in the period T8 is the second control.

[0113] Here, alternating between forward and reverse rotation may include at least one of forward and reverse rotation, or reverse and forward rotation. Therefore, when alternating between forward and reverse rotation, the number of forward and reverse rotations may be at least one. In addition, in the first control, it is preferable to have the motor M1 perform reverse rotation after forward rotation.

[0114] Moreover, after the motor M1 rotates in the forward direction during the period T4, the motor M1 rotates in the reverse direction during the period T5. Thus, in the first control, when the motor M1 is rotating in the forward direction and the number of times that the impact motion is detected by the impact detection unit 112 becomes equal to or greater than the switching threshold, the motor control unit 115 causes the motor M1 to rotate in the reverse direction. The switching threshold is, for example, a value within the range of 100 to 200 times.

[0115] (2.4) Judgment process Next, the judgment process for the period T3 (judging whether or not there is an abnormality in the screw tightening) will be described. In the period T3, only the portion near the tip of the screw part B12 is inserted into the screw hole W10 of the workpiece W1, so if there is no abnormality in the screw tightening, no impact motion will occur. Therefore, the motor control unit 115 judges that there is an abnormality in the screw tightening if the number of times that the impact motion is detected by the impact detection unit 112 becomes equal to or greater than a predetermined number during the period from the start of the period T3 until the rotation angle of the motor M1 reaches a certain rotation angle (until the end of the period T3). In other words, when the motor M1 is performing a forward rotation operation in which the motor M1 rotates in the direction in which the screw B1 is tightened and the screw B1 is first inserted into the screw hole W10, if the number of times that the impact motion is detected by the impact detection unit 112 becomes equal to or greater than a predetermined number during the period from the start of the period T3 until the rotation angle of the motor M1 reaches a certain rotation angle (period T3), the motor control unit 115 judges that there is an abnormality in the screw tightening. Furthermore, if the number of times that the impact motion is detected by the impact detection unit 112 during the period T3 is less than a predetermined number, the motor control unit 115 determines that there is no abnormality in the screw tightening. The predetermined number is, for example, once, several times, or several tens of times.

[0116] Next, the judgment process for the period T4 will be described. In the period T4, an impact operation is performed if normal. If the number of times that the impact operation is detected by the impact detection unit 112 is less than a predetermined number during the period from the start of the period T4 until the rotation angle of the motor M1 reaches a certain rotation angle, the motor control unit 115 judges that there is an abnormality in the screw tightening. If the number of times that the impact operation is detected by the impact detection unit 112 is equal to or greater than a predetermined number during the period from the start of the period T4 until the rotation angle of the motor M1 reaches a certain rotation angle, the motor control unit 115 judges that there is no abnormality in the screw tightening. The predetermined number is, for example, once, several times, or several tens of times.

[0117] The judgment process for the period T5 will be described. In the period T5, if it is normal, the screw B1 will loosen after a while and the impact motion will cease. Therefore, if the number of times the impact motion is detected by the impact detection unit 112 is less than a predetermined number during the period from the start of the period T5 until the rotation angle of the motor M1 reaches a certain rotation angle, the motor control unit 115 judges that there is no abnormality in the screw tightening. In other words, after the motor M1 performs the forward rotation operation, in the judgment process, if the number of times the impact motion is detected by the impact detection unit 112 is less than a predetermined number during the period from the start of the period T5 until the rotation angle of the motor M1 reaches a certain rotation angle during the reverse rotation operation (period T5), the motor control unit 115 judges that there is an abnormality in the screw tightening. Also, if the number of times the impact motion is detected by the impact detection unit 112 becomes equal to or greater than a predetermined number during the period T5, the motor control unit 115 judges that there is an abnormality in the screw tightening. The predetermined number is, for example, several tens of times.

[0118] Furthermore, after determining that there is no abnormality in the screw tightening while the reverse rotation operation is being performed (period T5), the motor control unit 115 causes the motor M1 to perform a further reverse rotation operation by a predetermined rotation angle during period T6.

[0119] The judgment process for period T6 will be described. During period T6, the screw B1 is loose, so if it is normal, there is no impact motion. Therefore, if the number of times that the impact motion is detected by the impact detection unit 112 during the period from the start of period T6 until the rotation angle of the motor M1 reaches a certain rotation angle (period T6) is equal to or greater than a predetermined number, the motor control unit 115 judges that there is an abnormality in the screw tightening. Also, if the number of times that the impact motion is detected by the impact detection unit 112 during period T6 is less than the predetermined number, the motor control unit 115 judges that there is no abnormality in the screw tightening. The predetermined number is, for example, once, several times, or several tens of times.

[0120] Further, another example of the judgment process for the period T6 will be described. In the period T6, the motor control unit 115 detects the rotation angle of the motor M1 during the period from the detection of the impact operation to the detection of the next impact operation. The situation where the rotation angle of the motor M1 during this period is equal to or greater than a predetermined value corresponds to the situation where the screw B1 is loosened. Therefore, the motor control unit 115 judges that there is no abnormality in the screw tightening if the rotation angle of the motor M1 during the period from the detection of the impact operation to the detection of the next impact operation becomes equal to or greater than a predetermined value during the period from the start of the period T6 until the rotation angle of the motor M1 reaches a certain rotation angle. Also, the motor control unit 115 judges that there is an abnormality in the screw tightening if the rotation angle of the motor M1 during the period from the detection of the impact operation to the detection of the next impact operation is less than a predetermined value throughout the period from the start of the period T6 until the rotation angle of the motor M1 reaches a certain rotation angle.

[0121] The judgment process for the period T7 will be described. Since the screw portion B12 is passed through the screw hole W10 in the period T6, burrs and dirt on the screw portion B12 and the screw hole W10 are removed to a certain extent. Therefore, if it is normal, an impact operation is unlikely to occur in the period T7. Therefore, the motor control unit 115 judges that there is an abnormality in the screw fastening if the number of times that the impact operation is detected by the impact detection unit 112 becomes equal to or greater than a predetermined number during the period from the start of the period T7 until the rotation angle of the motor M1 reaches a certain rotation angle. In other words, after the motor M1 performs the reverse rotation operation, in the judgment process, the motor control unit 115 judges that there is an abnormality in the screw fastening if the number of times that the impact operation is detected by the impact detection unit 112 becomes equal to or greater than a predetermined number during the period from the start of the period T7 until the rotation angle of the motor M1 when the motor M1 is performing the forward rotation operation reaches a certain rotation angle (period T7). Also, if the number of times that the impact operation is detected by the impact detection unit 112 is less than the predetermined number during the period T7, the motor control unit 115 judges that there is no abnormality in the screw fastening. The predetermined number is, for example, once, several times, or several tens of times.

[0122] During period T8, there is no particular need for a judgment process to judge whether or not there is an abnormality in the screw tightening. However, during period T8, the motor control unit 115 may stop the motor M1 when it is judged that the fastening torque calculated by the torque calculation unit 114 is equal to or greater than a predetermined torque. The torque calculation unit 114 may calculate the fastening torque based on the detection result of the torque sensor 13 as described above, or may calculate the fastening torque based on the number of times the impact operation is detected and the current of the motor M1 detected by the current detection unit 116.

[0123] As described above, when the first signal is a high-level signal and the second signal is a low-level signal, the motor control unit 115 causes the motor M1 to rotate in the reverse direction. In this case, no particular determination process is required.

[0124] (Modification of the embodiment) Modifications of the embodiment are listed below. The following modifications may be implemented in appropriate combination. Hereinafter, the configuration of the above-described embodiment will be referred to as a basic example. Configurations similar to those of the basic example will be given the same reference numerals and will not be described.

[0125] (Variation 1) The present modified example 1 differs from the basic example in that the current of the motor M1 detected by the current detection unit 116 is also used in the determination process for determining whether or not there is an abnormality in the screw tightening.

[0126] That is, in the judgment process of the present modified example 1, if it is provisionally determined in at least one of the first provisional judgment process and the second provisional judgment process that there is an abnormality in the screw tightening, the motor control unit 115 determines that there is an abnormality in the screw tightening.

[0127] In the first determination process, the presence or absence of an abnormality in screw tightening is provisionally determined based on the relationship between the rotation angle of the motor M1 and the detection result of the impact detection unit 112 as to whether or not an impact operation has occurred.

[0128] In the second determination process, the presence or absence of an abnormality in screw tightening is provisionally determined based on the current detected by the current detection unit 116.

[0129] As an example, the conditions for provisionally determining that there is an abnormality in the screw tightening in the first judgment process are the same as the conditions for determining that there is an abnormality in the screw tightening in the judgment process of the basic example.

[0130] Also, as an example, in the second determination process, if the current detected by the current detection unit 116 exceeds the current threshold, it is provisionally determined that there is an abnormality in the screw tightening. This makes it possible to determine that an excessive load in the screw tightening is an abnormality.

[0131] Instead of comparing the current (instantaneous value) with a current threshold, the amount of change in current per unit time may be compared with a corresponding threshold. For example, if the amount of change in current per unit time exceeds a corresponding threshold, it may be provisionally determined that there is an abnormality in the screw tightening.

[0132] According to this modification 1, even if the target (workpiece W1) to be fastened with the screw is soft and no impact action occurs, the motor control unit 115 can determine the presence or absence of an abnormality in the fastening of the screw based on the current. This makes it possible to more reliably find an abnormality in the fastening of the screw.

[0133] The second determination process may be executed only when the impact detection section 112 determines that no impact motion has occurred.

[0134] (Variation 2) During period T6, as shown in Fig. 6D, the motor control unit 115 rotates the motor M1 in the reverse direction by a fixed rotation angle to loosen the screw B1. Here, in this modification 2, the "fixed rotation angle" during period T6 is determined by the motor control unit 115 in accordance with the length L1 of the screw portion B12. Information indicating the length L1 of the screw portion B12 is input by a user's operation. For example, information indicating the length L1 of the screw portion B12 is input by a user's operation of the operation unit 57 (see Fig. 1).

[0135] It is preferable to determine the above-mentioned constant rotation angle so that the screw B1 moves a distance L2 obtained by multiplying the length L1 of the screw portion B12 by a constant ratio (the constant ratio is less than 1, for example, 0.9) between the start and end of the period T6. This makes it possible to prevent the screw portion B12 from coming off the screw hole W10. Then, during the period T7 in which the motor M1 is operated in the forward direction, the presence or absence of an abnormality can be determined for the constant distance L2 according to the length L1 of the screw portion B12. Specifically, during the period T7, for example, it can be determined whether or not galling has occurred between the screw B1 and the screw hole W10 within the range of the distance L2.

[0136] (Other variations) The robot 50 of the basic example is equipped with a robot arm 51 having six degrees of freedom, but the configuration of the robot arm 51 is not limited to that of the basic example. It is preferable that the robot 50 is equipped with, for example, a multi-joint type robot arm having two or more joints.

[0137] In the basic example, one power tool 10 is attached to one robot 50, but multiple power tools 10 may be attached to one robot 50.

[0138] Although the basic example power tool system 100 has only one robot 50 with one power tool 10 attached thereto, the power tool system 100 may have multiple robots 50 with one or more power tools 10 attached thereto, respectively.

[0139] The external device 50 a that issues a command to the motor control unit 115 may be a device separate from the robot 50 .

[0140] 3 is a socket attached to the outer edge of the screw B1, but the shape of the tip tool 23 can be changed as appropriate. The tip tool 23 may be shaped, for example, as a Phillips or flat head screwdriver that is inserted into a hole in the head B11 of the screw B1. The tip tool 23 may also be attached directly to the output shaft 22 without using the holder 24 and the coil spring 25.

[0141] In the power tool 10 of the basic example, the notification unit 113 notifies the result of the determination process of the motor control unit 115 by both sound and light, but the notification unit 113 may notify by either sound or light. Furthermore, the notification unit 113 may notify the result of the determination process of the motor control unit 115 to an external device (for example, a mobile terminal or wearable terminal carried by the operator, or the centralized management unit 40, etc.).

[0142] The power tool 10 may be a portable tool that is held by an operator and operates in response to the operator's operation.

[0143] The power tool 10 may include a shock sensor. The shock sensor outputs an output signal having a magnitude corresponding to the magnitude of vibration applied to the shock sensor. The impact detection unit 112 may detect the presence or absence of an impact operation based on the output signal from the shock sensor. For example, the impact detection unit 112 determines that an impact operation is being performed when the output signal exceeds the threshold value from a state where the output signal is below the threshold value. Then, for example, the impact detection unit 112 determines that an impact operation is not being performed when the output signal remains below the threshold value for a predetermined period of time or more. The shock sensor may be disposed at a position where vibrations generated by the impact operation are transmitted. For example, the shock sensor may be disposed near the hammer 74.

[0144] The change in the command rotation speed over time shown in FIG. 5 is an example and can be changed as appropriate. For example, at least one of the periods T1, T2, T4, T5, and T7 may be omitted. Whether or not to omit each of the periods T1, T2, T4, T5, and T7 may be determined by a user's operation. For example, whether or not to omit each of the periods T1, T2, T4, T5, and T7 may be determined by a user's operation of the operation unit 57 (see FIG. 1).

[0145] The relationship between the high level or low level signals of the first and second signals and the command contents may be the opposite of that in the basic example. That is, when the first signal is a low level signal, the motor control unit 115 may rotate the motor M1, and when the first signal is a high level signal, the motor control unit 115 may stop the motor M1. Also, when the second signal is a low level signal, the motor control unit 115 may control the motor M1 to tighten the screw B1, and when the second signal is a high level signal, the motor control unit 115 may control the motor M1 to loosen the screw B1.

[0146] The power tool system 100, the power tool 10, or the control method for the power tool 10 in the present disclosure includes a computer system. The computer system is mainly composed of a processor and a memory as hardware. The processor executes a program recorded in the memory of the computer system to realize at least a part of the functions of the power tool system 100, the power tool 10, or the control method for the power tool 10 in the present disclosure. The program may be pre-recorded in the memory of the computer system, provided through an electric communication line, or provided 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 ICs or LSIs are called by different names depending on the degree of integration, and include integrated circuits called system LSIs, VLSIs (Very Large Scale Integration), or ULSIs (Ultra Large Scale Integration). Furthermore, a field-programmable gate array (FPGA) that is programmed after the manufacture of an LSI, or a logic device that allows reconfiguration of the connection relationship within the LSI or reconfiguration of the circuit partition within the LSI, can also be employed as a processor. The electronic circuits may be integrated into one chip, or may be distributed among multiple chips. The chips may be integrated into one device, or may be 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.

[0147] Furthermore, it is not essential for power tool 10 that multiple functions are concentrated in a single housing, and multiple components of power tool 10 may be distributed across multiple housings.

[0148] Conversely, in the embodiment, at least some of the functions of the power tool system 100 that are distributed among multiple housings may be consolidated into one housing. For example, multiple functions that are distributed between the centralized management unit 40 and the control device 60 may be consolidated into one housing.

[0149] (summary) The above-described embodiments and the like disclose the following aspects.

[0150] The power tool (10) according to the first embodiment is a power tool (10) for tightening a screw (B1). The power tool (10) includes a motor (M1), a hammer (74), an anvil (75), an output shaft (22), an impact detection unit (112), a motor control unit (115), and a memory unit (117). The hammer (74) rotates by receiving power from the motor (M1). The anvil (75) rotates by receiving an impact force from the hammer (74) in the rotation direction of the hammer (74). The output shaft (22) is configured to hold a tool tip (23) that transmits torque to the screw (B1), and rotates together with the anvil (75). The impact detection unit (112) detects the presence or absence of an impact operation, which is an operation in which the hammer (74) applies an impact force to the anvil (75). The motor control unit (115) controls the operation of the motor (M1) based on a command from an external device (50a) outside the power tool (10). The storage unit (117) stores information for the motor control unit (115) to perform a default control of the motor (M1). When the motor control unit (115) receives a predetermined command from the external device (50a), the motor control unit (115) tightens the screw (B1) by a default control of the motor (M1). The motor control unit (115) executes a determination process to determine the presence or absence of an abnormality in the tightening of the screw based on the relationship between the rotation angle of the motor (M1) and the detection result of the impact detection unit (112) as to the presence or absence of an impact operation. The default control includes stopping the motor (M1) when it is determined as a result of the determination process that there is an abnormality in the tightening of the screw.

[0151] According to the above configuration, it is possible to accurately determine whether or not there is an abnormality in screw tightening in the power tool (10) that performs an impact operation, and to stop the motor (M1) if there is an abnormality.

[0152] In the power tool (10) according to the second aspect, in the first aspect, the default control includes a first control and a second control. In the first control, the motor (M1) is caused to alternately perform a forward rotation operation in which the motor (M1) rotates in a direction to tighten the screw (B1) and a reverse rotation operation in which the motor (M1) rotates in a direction opposite to the forward rotation operation. In the second control, when it is determined as a result of the determination process that there is no abnormality in the tightening in the first control, the motor (M1) is caused to perform a forward rotation operation to tighten the screw (B1).

[0153] According to the above configuration, burrs and dirt on the screw (B1) and the object (workpiece (W1)) to be fastened by the screw (B1) can be removed by the reverse rotation. This reduces the possibility that burrs and dirt will interfere with the fastening of the screw in the second control. Therefore, the occurrence of abnormalities in the fastening of the screw can be suppressed.

[0154] In addition, in the power tool (10) according to the third aspect, in the second aspect, in the first control, when the motor (M1) is performing forward rotation, the motor control unit (115) causes the motor (M1) to perform reverse rotation when the number of times that the impact motion is detected by the impact detection unit (112) becomes equal to or greater than a switching threshold value.

[0155] According to the above configuration, the screw (B1) is tightened to an appropriate depth according to the switching threshold, and then the reverse rotation is performed, whereby burrs and dirt can be removed to the above-mentioned depth.

[0156] In addition, in the power tool (10) according to the fourth aspect, in any one of the first to third aspects, after the motor (M1) performs a reverse operation in which it rotates in the opposite direction to the direction for tightening the screw (B1), in the judgment process, the motor control unit (115) judges that there is an abnormality in the screw tightening if the number of times that the impact operation is detected by the impact detection unit (112) becomes equal to or exceeds a predetermined number before the rotation angle of the motor (M1) when the motor (M1) performs a forward operation in which it rotates in the direction for tightening the screw (B1) reaches a certain rotation angle.

[0157] According to the above configuration, the motor control unit (115) can determine the presence or absence of an abnormality, such as the occurrence of galling.

[0158] In addition, in the power tool (10) according to the fifth aspect, in any one of the first to fourth aspects, after the motor (M1) performs a forward rotation operation in which it rotates in a direction to tighten the screw (B1), in the judgment process, the motor control unit (115) judges that there is no abnormality in the screw tightening if the number of times that the impact operation is detected by the impact detection unit (112) is less than a predetermined number before the rotation angle of the motor (M1) during the reverse rotation operation in which it rotates in the opposite direction to the forward rotation operation reaches a certain rotation angle.

[0159] According to the above configuration, the motor control unit (115) can determine whether the screw (B1) has been properly loosened by the reverse rotation.

[0160] In the power tool (10) according to the sixth aspect, in the fifth aspect, the motor control unit (115) determines that there is no abnormality in the screw tightening when performing a reverse operation in which the motor rotates in the opposite direction to the forward operation, and then causes the motor (M1) to perform a reverse operation by a further predetermined rotation angle.

[0161] According to the above configuration, the screw (B1) can be sufficiently loosened.

[0162] In addition, in the power tool (10) of the seventh aspect, in any one of the first to sixth aspects, when the motor (M1) is performing a forward rotation operation to rotate in a direction to tighten the screw (B1) and the screw (B1) is initially inserted into the screw hole (W10), if the number of times that the impact operation is detected by the impact detection unit (112) becomes equal to or exceeds a predetermined number before the rotation angle of the motor (M1) reaches a certain rotation angle, the motor control unit (115) determines that there is an abnormality in the screw tightening.

[0163] According to the above configuration, the motor control unit (115) can determine the presence or absence of an abnormality, such as the occurrence of galling.

[0164] The power tool (10) according to an eighth aspect is any one of the first to seventh aspects, and further includes a current detection unit (116) that detects a current flowing through the motor (M1). The determination process determines that there is an abnormality in the screw tightening when it is provisionally determined in at least one of the first provisional determination process and the second provisional determination process that there is an abnormality in the screw tightening. In the first provisional determination process, the presence or absence of an abnormality in the screw tightening is provisionally determined based on the relationship between the rotation angle of the motor (M1) and the detection result of the impact detection unit (112) as to whether or not an impact motion has occurred. In the second provisional determination process, the presence or absence of an abnormality in the screw tightening is provisionally determined based on the current detected by the current detection unit (116).

[0165] According to the above configuration, even if the object (workpiece (W1)) to be fastened by the screw (B1) is soft and no impact action occurs, the motor control unit (115) can determine the presence or absence of an abnormality in the screw fastening based on the current.

[0166] The configurations other than those of the first aspect are not essential to the power tool (10) and may be omitted as appropriate.

[0167] A power tool system (100) according to a ninth aspect includes the power tool (10) according to any one of the first to eighth aspects and a robot arm (51). The robot arm (51) holds the power tool (10) and controls the position and posture of the power tool (10).

[0168] According to the above configuration, the screw tightening operation can be automated.

[0169] A power tool system (100) according to a tenth aspect includes the power tool (10) according to any one of the first to eighth aspects, and a robot (50). The robot (50) is an external device (50a) that issues commands to the motor control unit (115). The robot (50) includes a robot arm (51). The robot arm (51) holds the power tool (10) and controls the position and posture of the power tool (10).

[0170] According to the above configuration, the screw tightening operation can be automated.

[0171] A control method according to an eleventh aspect is a control method for a power tool (10) for tightening a screw (B1). The power tool (10) includes a motor (M1), a hammer (74), an anvil (75), an output shaft (22), and an impact detection unit (112). The hammer (74) rotates by receiving power from the motor (M1). The anvil (75) rotates by receiving an impact force from the hammer (74) in the rotation direction of the hammer (74). The output shaft (22) is configured to hold a tool tip (23) that transmits torque to the screw (B1), and rotates together with the anvil (75). The impact detection unit (112) detects the presence or absence of an impact operation, which is an operation in which the hammer (74) applies an impact force to the anvil (75). The control method is executed by a computer system. The control method includes, upon receiving a predetermined command from an external device (50a) outside the power tool (10), tightening the screw (B1) by a preset control of the motor (M1), and executing a determination process for determining the presence or absence of an abnormality in the tightening of the screw based on the relationship between the rotation angle of the motor (M1) and a detection result of the presence or absence of an impact operation by the impact detection unit (112). The preset control includes stopping the motor (M1) when it is determined as a result of the determination process that there is an abnormality in the tightening of the screw.

[0172] According to the above configuration, it is possible to accurately determine whether or not there is an abnormality in screw tightening in the power tool (10) that performs an impact operation, and to stop the motor (M1) if there is an abnormality.

[0173] A program according to a twelfth aspect is a program for causing one or more processors of a computer system to execute the control method according to the eleventh aspect.

[0174] According to the above configuration, it is possible to accurately determine whether or not there is an abnormality in screw tightening in the power tool (10) that performs an impact operation, and to stop the motor (M1) if there is an abnormality.

[0175] Without being limited to the above aspects, various configurations (including modified examples) of the power tool (10) and the power tool system (100) according to the embodiment can be embodied in a control method, a (computer) program, or a non-transitory recording medium having a program recorded thereon. [Explanation of symbols]

[0176] 10 Power tools 22 Output shaft 23 Tip tools 50 Robot 50a external equipment 51 Robot Arm 74 Hammer 75 Anvil 100 Power Tool System 112 Impact detection unit 115 Motor control unit 116 Current detection section 117 Memory section B1 Screw M1 Motor W10 screw hole

Claims

1. A power tool for tightening screws, 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 for transmitting torque to the screw and rotate with the anvil; an impact detection unit that detects the presence or absence of an impact motion, which is a motion in which the hammer applies the impact force to the anvil; a motor control unit that controls an operation of the motor based on a command from an external device outside the power tool; A storage unit that stores information for the motor control unit to perform a predetermined control on the motor, When the motor control unit receives a predetermined command from the external device, the motor control unit performs the tightening of the screw by the predetermined control of the motor, the motor control unit executes a determination process for determining whether or not there is an abnormality in the screw tightening based on a relationship between a rotation angle of the motor and a detection result of the impact detection unit as to whether or not there is an impact motion; and The predetermined control includes stopping the motor when it is determined that there is an abnormality in the screw tightening as a result of the determination process. Power tools.

2. The default control is: a first control for alternately causing the motor to perform a forward rotation operation in which the motor rotates in a direction for fastening the screw and a reverse rotation operation in which the motor rotates in a direction opposite to the forward rotation operation; and a second control for causing the motor to perform the forward rotation operation to tighten the screw when it is determined that there is no abnormality in the screw tightening in the first control as a result of the determination process. The power tool according to claim 1.

3. In the first control, when the motor is performing the forward rotation operation, the motor control unit causes the motor to perform the reverse rotation operation when a number of times the impact motion is detected by the impact detection unit becomes equal to or greater than a switching threshold value. The power tool according to claim 2.

4. After the motor performs a reverse operation in which it rotates in a direction opposite to the direction in which the screw is tightened, in the judgment process, if the number of times that the impact operation is detected by the impact detection unit becomes equal to or exceeds a predetermined number during the period until the rotation angle of the motor when the motor performs a forward operation in which it rotates in the direction in which the screw is tightened reaches a certain rotation angle, the motor control unit judges that there is an abnormality in the screw tightening. The power tool according to claim 1.

5. After the motor performs a forward rotation operation in which it rotates in a direction for tightening the screw, in the judgment process, if the number of times that the impact operation is detected by the impact detection unit is less than a predetermined number during the time until the rotation angle of the motor during a reverse rotation operation in which the motor rotates in the opposite direction to the forward rotation operation reaches a certain rotation angle, the motor control unit judges that there is no abnormality in the screw tightening. The power tool according to claim 1.

6. the motor control unit determines that there is no abnormality in the screw fastening while performing a reverse rotation operation in which the motor rotates in the opposite direction to the forward rotation operation, and then causes the motor to perform the reverse rotation operation by a further predetermined rotation angle. The power tool according to claim 5.

7. the motor control unit determines that there is an abnormality in the screw tightening if the number of times the impact motion is detected by the impact detection unit becomes equal to or exceeds a predetermined number during the time period until the rotation angle of the motor reaches a certain rotation angle when the screw is initially inserted into the screw hole while the motor is performing a forward rotation operation rotating in a direction for tightening the screw, The power tool according to claim 1.

8. A current detection unit that detects a current flowing through the motor is further provided. The determination process includes: a first provisional determination process for provisionally determining whether or not there is an abnormality in the screw tightening based on the relationship between the rotation angle of the motor and the detection result of the impact detection unit as to whether or not there is an impact operation; a second provisional determination process for provisionally determining whether or not there is an abnormality in the screw tightening based on the current detected by the current detection unit; and a determination that there is an abnormality in the screw tightening when it is provisionally determined that there is an abnormality in the screw tightening in at least one of the first and second provisional determination processes. The power tool according to claim 1.

9. The power tool according to claim 1 ; a robot arm that holds the power tool and controls a position and posture of the power tool. Power tool system.

10. The power tool according to claim 1 ; a robot as the external device that issues a command to the motor control unit, The robot comprises: a robot arm for holding the power tool and controlling a position and a posture of the power tool; Power tool system.

11. A method for controlling an electric power tool for tightening a screw, comprising the steps of: The power tool comprises: 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 for transmitting torque to the screw and rotate with the anvil; an impact detection unit that detects the presence or absence of an impact motion, which is an operation of the hammer applying the impact force to the anvil; The control method is executed by a computer system, The control method includes: When a predetermined command is received from an external device outside the power tool, the screw is tightened by a predetermined control of the motor. and executing a determination process for determining whether or not there is an abnormality in the screw tightening based on a relationship between a rotation angle of the motor and a detection result of the impact operation by the impact detection unit, The predetermined control includes stopping the motor when it is determined that there is an abnormality in the screw tightening as a result of the determination process. How to control power tools.

12. 12. A method for causing one or more processors of the computer system to execute the control method according to claim 11, program.

Images