Fastening tool

Abstract

To provide a fastening tool capable of restraining or preventing dispersion of a stop position when a driving mechanism stops.SOLUTION: The fastening tool includes a motor having a motor shaft, a housing, a pin-gripping part, a driving mechanism connected to the pin-gripping part and configured to perform rearward movement and forward movement, a position acquisition part configured to acquire a relative position of the driving mechanism, and a motor control part configured to switch a moving direction and a moving speed of the driving mechanism. The motor control unit starts forward movement of the shaft such that the movement speed becomes a first speed, decelerates the movement speed to a second speed slower than the first speed by PWM control for changing a duty ratio output to the motor when the acquired relative position reaches a deceleration position behind the initial position in the forward movement, and stops driving of the motor when the acquired relative position reaches a predetermined braking position in front of the deceleration position and behind the initial position.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure relates to a fastening tool. [Background technology]

[0002] A fastening tool is known that fastens workpieces via a fastener by pulling a pin included in the fastener. In such a fastening tool, a drive mechanism connected to a pin gripper is moved rearward from an initial position by the power of a motor, thereby pulling the pin rearward along a drive shaft. The rearward-moving drive mechanism is then moved from the rear toward the initial position by the power of the motor. For example, Patent Document 1 discloses a fastening tool in which, when the drive mechanism moving toward the initial position enters the detection range of a sensor disposed at the initial position, the motor is braked to stop the drive mechanism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-000892 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional technology, the stopping position of the drive mechanism may vary in the initial position, which may cause the pin gripping portion to be unable to grip the pin properly. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] According to a first aspect of the present disclosure, there is provided a fastening tool for fastening work materials via a fastener having a pin and a cylindrical portion. The fastening tool includes: a motor including a motor shaft; a housing that accommodates the motor; a pin gripping portion configured to grip the pin; a drive mechanism connected to the pin gripping portion, the drive mechanism configured to move rearward from an initial position along a drive axis that defines a front-to-rear direction of the fastening tool by forward rotation of the motor shaft; and to move forward from rearward to the initial position along the drive axis by reverse rotation of the motor shaft; a position acquisition portion configured to acquire the relative position of the drive mechanism in the front-to-rear direction with respect to the housing; and a motor control portion configured to drive and control the motor and to switch the movement direction and movement speed of the drive mechanism. The motor control unit starts the forward movement of the drive mechanism so that the movement speed becomes a first speed, and when the acquired relative position during the forward movement reaches a deceleration position behind the initial position, decelerates the movement speed to a second speed slower than the first speed by PWM control that changes the duty ratio output to the motor, and stops driving the motor when the acquired relative position reaches a predetermined braking position ahead of the deceleration position and behind the initial position.

[0007] According to the fastening tool of the above aspect, the driving of the motor is stopped after the movement speed of the drive mechanism is decelerated, thereby suppressing or preventing variation in the stopping position of the drive mechanism when it stops during forward movement. By using PWM control, the rotation speed of the motor shaft can be precisely switched, and the movement speed of the drive mechanism can be precisely switched. Therefore, it is possible to suppress or prevent the pin gripping portion from being unable to properly grip the pin.

[0008] According to a second aspect of the present disclosure, there is provided a fastening tool for fastening work materials via a fastener having a pin and a cylindrical portion. The fastening tool includes: a motor including a motor shaft; a housing that accommodates the motor; a pin gripping portion configured to grip the pin; a drive mechanism connected to the pin gripping portion, the drive mechanism configured to move rearward from an initial position along a drive axis that defines a front-to-rear direction of the fastening tool by forward rotation of the motor shaft; and to move forward from rearward to the initial position along the drive axis by reverse rotation of the motor shaft; a position acquisition portion configured to acquire the relative position of the drive mechanism in the front-to-rear direction with respect to the housing; and a motor control portion configured to drive and control the motor and to switch the movement direction and movement speed of the drive mechanism. The motor control unit starts the forward movement of the drive mechanism so that the movement speed becomes a first speed, and when the acquired relative position during the forward movement reaches a deceleration position rearward of the initial position, decelerates the movement speed to a second speed slower than the first speed by constant rotation speed control that adjusts the drive voltage of the motor so that the rotation speed per unit time of the motor shaft becomes a predetermined target rotation speed, and stops driving the motor when the acquired relative position reaches a predetermined braking position forward of the deceleration position and rearward of the initial position.

[0009] According to the fastening tool of the above aspect, since the driving of the motor is stopped after the moving speed of the drive mechanism is decelerated, it is possible to suppress or prevent variation in the stopping position when the drive mechanism stops during forward movement of the drive mechanism. Constant rotation speed control allows the moving speed of the drive mechanism to be switched with precision. Therefore, it is possible to suppress or prevent the pin gripping portion from being unable to grip the pin properly.

[0010] According to a third aspect of the present disclosure, there is provided a fastening tool for fastening work materials via a fastener having a pin and a tubular portion. The fastening tool includes: a motor including a motor shaft; a housing that accommodates the motor; a pin gripping portion configured to grip the pin; a drive mechanism connected to the pin gripping portion, the drive mechanism configured to move rearward from an initial position along a drive axis that defines a front-to-rear direction of the fastening tool by forward rotation of the motor shaft; and to move forward from rearward to the initial position along the drive axis by reverse rotation of the motor shaft; a position acquisition portion configured to acquire the relative position of the drive mechanism in the front-to-rear direction with respect to the housing; and a motor control portion configured to drive and control the motor and to switch the movement direction and movement speed of the drive mechanism. The motor control unit starts the forward movement of the drive mechanism so that the movement speed becomes a first speed, and when the movement speed reaches the first speed during the forward movement, determines a negative acceleration so that the movement speed at a braking position a predetermined distance behind the initial position becomes a second speed slower than the first speed, decelerates the movement speed at the determined acceleration, and stops driving the motor when the acquired relative position reaches the braking position.

[0011] According to the fastening tool of the above aspect, since the driving of the motor is stopped after the moving speed of the drive mechanism is decelerated, it is possible to suppress or prevent variation in the stopping position of the drive mechanism when it stops during forward movement of the drive mechanism, and therefore it is possible to suppress or prevent the pin gripping portion from being unable to grip the pin properly. The present disclosure can also be realized in various forms other than a fastening tool, such as a control method for a fastening tool, a computer program for realizing the control method, or a non-transitory recording medium on which the computer program is recorded. [Brief explanation of the drawings]

[0012] [Figure 1]FIG. 1 is an explanatory diagram showing an example of a breakable fastener that can be used with the fastening tool according to the present disclosure. [Figure 2] FIG. 10 is a longitudinal cross-sectional view of the fastening tool when the screw shaft is placed in the initial position. [Figure 3] FIG. 4 is an explanatory diagram showing an enlarged rear portion of the fastening tool. [Figure 4] FIG. [Figure 5] FIG. 4 is an explanatory diagram showing an enlarged front portion of the fastening tool. [Figure 6] FIG. 2 is a block diagram showing the electrical configuration of the fastening tool. [Figure 7] FIG. 2 is a block diagram showing the internal functional configuration of a controller. [Figure 8] FIG. 4 is an explanatory diagram showing the relationship between the position of the screw shaft and the first and second sensors. [Figure 9] 10 is a flowchart showing a drive control process of the motor when the screw shaft moves backward. [Figure 10] 10 is a flowchart showing a drive control process of the motor when the screw shaft moves forward. [Figure 11] 4 is a timing chart showing the operation of each part in one cycle of the fastening process. [Figure 12] 10 is a flowchart showing a motor drive control process according to a second embodiment. [Figure 13] 10 is a timing chart of a fastening process performed by a fastening tool according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Representative, non-limiting embodiments of the present invention will now be described in detail with reference to the accompanying drawings. This detailed description is intended simply to provide those skilled in the art with details for implementing preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Additionally, additional features and inventions disclosed below may be used separately or in conjunction with other features and inventions to provide further improved devices, methods of making and using the same.

[0014] Furthermore, the combinations of features and steps disclosed in the following detailed description are not essential to practicing the invention in its broadest sense, but are described solely to illustrate specific exemplary embodiments of the invention. Furthermore, the various features of the exemplary embodiments described above and below, and those described in the independent and dependent claims, do not necessarily have to be combined in the exact embodiments described herein, or in the exact order listed, to provide additional and useful embodiments of the invention.

[0015] All features described in this specification and / or claims are intended to be disclosed individually and independently of one another as limitations on the original disclosure and claimed particulars, apart from any configuration of the features described in the embodiments and / or claims. Furthermore, all numerical ranges and group or aggregation descriptions are intended to disclose intermediate configurations thereof as limitations on the original disclosure and claimed particulars.

[0016] In one or more embodiments, the position acquisition unit may acquire a rotation speed of the motor shaft, and acquire the relative position using the acquired rotation speed of the motor shaft. According to this configuration, the position of the drive mechanism can be obtained in a simple manner.

[0017] In one or more embodiments, the position acquisition unit may determine that the deceleration position has been reached when the number of rotations acquired during the forward movement reaches a predetermined number of rotations. This configuration eliminates the need for a detector for detecting the target of the drive mechanism located at the deceleration position, thereby preventing an increase in the number of components in the fastening tool. Also, the deceleration position can be set and changed more easily than when a detector is provided.

[0018] In one or more embodiments, the number of rotations of the motor shaft from the position where the forward movement starts to the deceleration position may be configured to be less than the number of rotations of the motor shaft from the position where counting the number of rotations of the motor shaft starts during the backward movement to the position where the forward movement starts by a predetermined number of rotations. According to this configuration, the number of rotations of the motor shaft can be used to set the deceleration position behind the position at which counting of the number of rotations of the motor shaft starts.

[0019] In one or more embodiments, the position acquisition unit may acquire a rotation speed of the motor shaft. The shaft position acquisition unit may use the acquired rotation speed of the motor shaft to acquire an arrival position at which the moving speed reaches the first speed. The shaft position acquisition unit may calculate a distance from the acquired arrival position to the braking position. The motor control unit may calculate the acceleration using the calculated distance from the arrival position to the braking position, and decelerate the moving speed by the calculated acceleration. With this configuration, even if the arrival position fluctuates, the movement speed at the braking position can be decelerated to the target speed, thereby suppressing or preventing variations in the stopping position of the drive mechanism due to fluctuations in the arrival position.

[0020] In one or more embodiments, the motor control unit may decelerate the moving speed at a constant negative acceleration corresponding to the acquired distance from the arrival position to the braking position. This configuration makes it possible to reduce the cost of calculating acceleration.

[0021] In one or more embodiments, the vehicle may further include a detection target provided in the drive mechanism and moving integrally with the drive mechanism, and a braking position detection unit configured to detect the detection target provided in the drive mechanism when the drive mechanism is placed at the braking position. The position acquisition unit may start acquiring the rotation speed of the motor shaft at a timing when, during the backward movement, the detection result by the braking position detection unit switches from a detection state in which the detection target is detected to a non-detection state in which the detection target is not detected. This configuration can improve the accuracy of estimating the position of the drive mechanism compared to a configuration in which acquisition of the rotation speed of the motor shaft begins from the timing when the drive mechanism starts to move.

[0022] In one or more embodiments, the motor control unit may switch the movement speed by PWM control that changes a duty ratio output to the motor. According to this configuration, the rotation speed of the motor shaft can be switched with high precision by PWM control, and the movement speed of the drive mechanism can be switched with high precision.

[0023] In one or more embodiments, the motor control unit may perform constant rotation speed control to adjust a drive voltage of the motor so that the number of rotations per unit time of the motor shaft becomes a predetermined target rotation speed, and the motor control unit may switch the movement speed by switching the target rotation speed. According to this configuration, the movement speed of the drive mechanism can be switched with high precision by constant rotation speed control.

[0024] In one or more embodiments, the motor controller may stop the motor by a short circuit brake that shorts terminals of the motor. This configuration can shorten the time required to stop the motor, shorten the braking distance of the drive mechanism, and reduce variations in the stopping position of the drive mechanism.

[0025] In one or more embodiments, the drive mechanism may include a nut that is driven to rotate about the drive shaft by power from the motor, and a shaft coupled to the pin gripping portion, the shaft configured so that forward rotation of the motor shaft causes the rearward movement and reverse rotation of the motor shaft causes the forward movement. According to this configuration, the so-called feed screw mechanism allows the movement direction and movement speed of the drive mechanism to be switched with high precision.

[0026] In one or more embodiments, the vehicle may include a detection target provided in the drive mechanism and moving integrally with the drive mechanism, and a rear braking position detector configured to detect the detection target provided in the drive mechanism when the drive mechanism is positioned at a rear braking position rearward of the braking position. The motor control unit may stop driving the motor when the detection target is detected by the rear braking position detector. According to this configuration, the drive mechanism at the rear detection position can be detected by a method that is simpler than when the position of the drive mechanism is estimated using the rotation speed of the motor.

[0027] In one or more embodiments, the motor control unit may further include a trigger capable of receiving a pressing operation and a release operation for releasing the pressing operation. When the trigger receives the pressing operation, the motor control unit may drive the motor to rotate the motor shaft in the forward direction, and when the trigger receives the release operation, the motor control unit may drive the motor to rotate the motor shaft in the reverse direction. According to this configuration, the user can switch between the forward movement and the backward movement of the drive mechanism by simply operating the trigger.

[0028] A. First embodiment: A1.Fastener configuration: FIG. 1 shows an example of a fastener that can be used with fastening tool 1. Fastener 9 includes pin 91 and collar 95. Fastener 9 is a breakable type in which a portion of shank 911 of pin 91, also known as the pintail or mandrel, breaks and is torn off. Collar 95 has a generally cylindrical shape and is configured so that shank 911 can be inserted therethrough. Collar 95 is an example of a "cylindrical portion."

[0029] A2. Appearance of fastening tool 1: Referring to Figure 2, a fastening tool 1 capable of fastening work materials using a fastener 9 will be described. As shown in Figure 2, the outer shell of the fastening tool 1 is formed by an outer housing 11, a handle 15, and a nose portion 16. The outer housing 11 is a substantially rectangular box extending along a predetermined drive axis A1. As shown in Figure 2, the outer housing 11 accommodates a motor 2, a drive mechanism 4, and a transmission mechanism 3. An inner housing 13 is fixed within the outer housing 11. The outer housing 11 and the inner housing 13 form an integrated housing 10.

[0030] The nose portion 16 is disposed to extend along the drive axis A1. The nose portion 16 includes a cylindrical anvil 161 and a pin gripping portion 165 disposed within the anvil 161. The anvil 161 is connected to one end of the outer housing 11 in the longitudinal direction. A collection container 7 capable of storing the shank 911 separated from the fastener 9 during the fastening process is detachably attached to the other end of the outer housing 11.

[0031] The handle 15 is configured to be grippable by a user and protrudes from approximately the center of the outer housing 11 in the longitudinal direction in a direction intersecting the drive axis A1 (in this embodiment, a direction substantially perpendicular to the drive axis A1).

[0032] In this specification, with regard to the direction of the fastening tool 1, the extension direction of the drive axis A1 (also referred to as the "longitudinal direction of the outer housing 11") is defined as the front-rear direction of the fastening tool 1. In the front-rear direction, the side where the nose portion 16 is located is defined as the front side, and the side where the collection container 7 is located is defined as the rear side. A direction perpendicular to the drive axis A1 and corresponding to the extension direction of the handle 15 is defined as the up-down direction. In the up-down direction, the side where the outer housing 11 is located is defined as the upper side, and the side of the protruding end (free end) of the handle 15 is defined as the lower side. In addition, a direction perpendicular to the front-rear direction and the up-down direction is defined as the left-right direction.

[0033] The upper end of the handle 15 functions as a base end that connects to the outer housing 11. The upper end of the handle 15 is provided with a trigger 151 that is configured to be able to accept a pressing operation (pulling operation) by the user and a release operation that releases the pressing operation. The lower end of the handle 15 is provided with a battery mounting section 158 that is configured to allow a battery 159 to be attached and detached. The battery 159 is a power source that can be repeatedly charged, and is, for example, a well-known battery pack or secondary battery such as a lithium-ion battery including multiple cells. The battery 159 supplies power to each section of the fastening tool 1 and the motor 2.

[0034] The fastening tool 1 is configured to be able to fasten work materials W1, W2 via a fastener 9. The fastener 9 is gripped by a pin gripping portion 165 (described later) with a portion of the shank 911 inserted into the tip of the nose portion 16 of the fastening tool 1 and the fastener 9 engaged with the tip of the anvil 161.

[0035] A3. Internal structure of fastening tool 1: 3 to 5, the internal configuration of the fastening tool 1 will be described. A motor 2, a drive mechanism 4 driven by the power of the motor 2, and a transmission mechanism 3 that transmits the power of the motor 2 to the drive mechanism 4 are housed within a housing 10.

[0036] The motor 2 is, for example, a brushless DC motor. As shown in FIG. 3 , the motor 2 is housed below the rear end of the outer housing 11. In this embodiment, the entire motor 2 is disposed below the drive shaft A1. The motor 2 includes a motor main body 20 and a motor shaft 25. The motor main body 20 includes a stator 21 and a rotor 23. The motor shaft 25 extends from the rotor 23 and is configured to rotate integrally with the rotor 23. The rotation axis A2 of the motor shaft 25 is configured to be downward and parallel to the drive shaft A1. The rotation axis A2 extends in the front-rear direction. The front end of the motor shaft 25 protrudes into the reducer housing 30. A fan 27 for cooling the motor 2 is fixed to the rear end of the motor shaft 25.

[0037] As shown in Fig. 3, the transmission mechanism 3 includes a planetary reducer 31, an intermediate shaft 33, and a nut drive gear 35. The planetary reducer 31 is disposed in front of the motor 2. Rotational power is transmitted from the motor shaft 25 to the planetary reducer 31. In the power transmission path from the motor 2 to the ball screw mechanism 40 of the drive mechanism 4, the planetary reducer 31 increases the torque of the motor 2 and transmits it to the intermediate shaft 33.

[0038] The planetary reducer 31 includes two planetary gear mechanisms and a resin reducer housing 30. The reducer housing 30 is disposed in front of the motor 2 and fixed to the outer housing 11. The reducer housing 30 houses the two planetary gear mechanisms. A sun gear 311 is fixed to the front end of the motor shaft 25. The sun gear 311 is the upstream planetary gear mechanism of the planetary reducer 31. The carrier 313 is the downstream planetary gear mechanism of the planetary reducer 31. The carrier 313 is the final output shaft of the planetary reducer 31.

[0039] The intermediate shaft 33 is rotatably disposed coaxially with the motor shaft 25. The rear end of the intermediate shaft 33 is coupled to the carrier 313. As a result, the intermediate shaft 33 rotates integrally with the carrier 313. The nut drive gear 35 is fixed to the outer periphery of the front end of the intermediate shaft 33. The nut drive gear 35 meshes with a driven gear 411 formed on the outer periphery of a nut 41 (described later), and transmits the rotational power of the intermediate shaft 33 to the nut 41. The nut drive gear 35 and the driven gear 411 form a reduction gear mechanism.

[0040] As shown in FIG. 3, the drive mechanism 4 is connected to a pin gripping portion 165 (see FIG. 5), which will be described later. The drive mechanism 4 moves in the front-rear direction along the drive axis A1 by the power of the motor 2, and moves the pin gripping portion 165 in the front-rear direction. In this embodiment, the drive mechanism 4 is configured by a ball screw mechanism 40 housed in the upper part of the outer housing 11. As shown in FIGS. 3 and 4, the ball screw mechanism 40 includes a nut 41 and a screw shaft 46. The ball screw mechanism 40 is configured to convert the rotational motion of the nut 41 into linear motion of the screw shaft 46, thereby moving the pin gripping portion 165 linearly.

[0041] The nut 41 is a cylindrical member. The nut 41 is supported by the inner housing 13 in a state where movement in the front-rear direction is restricted and the nut 41 is rotatable about the drive shaft A1. A driven gear 411 is formed on the outer periphery of the nut 41. The nut 41 is supported by the inner housing 13 via a pair of radial bearings 412, 413 provided on the front and rear sides of the driven gear 411 so as to be rotatable about the drive shaft A1. The driven gear 411 meshes with the nut drive gear 35. The driven gear 411 receives the rotational power of the motor 2 via the nut drive gear 35, causing the nut 41 to rotate about the drive shaft A1.

[0042] The screw shaft 46 is a substantially long cylindrical member extending along the drive axis A1. The screw shaft 46 is an example of a "shaft." The screw shaft 46 is inserted through the nut 41. The screw shaft 46 is engaged with the nut 41 in a state where it can move in the front-rear direction along the drive axis A1. A spiral track is formed between the screw shaft 46 and the nut 41. The spiral track is defined between a spiral groove formed on the inner peripheral surface of the nut 41 and a spiral groove formed on the outer peripheral surface of the screw shaft 46. A plurality of balls (not shown) are rollably disposed on the spiral track. The screw shaft 46 is engaged with the nut 41 via the plurality of balls. The screw shaft 46 moves linearly in the front-rear direction along the drive axis A1 as the nut 41 is rotated.

[0043] As shown in FIG. 4 , a central portion of a roller holding portion 463 is fixed to the rear end of the screw shaft 46. The roller holding portion 463 has an arm portion. The arm portion is a member that is perpendicular to the screw shaft 46 and protrudes in the left-right direction from the central portion of the roller holding portion 463. Rollers 464 are rotatably held at each end of the arm portion. Meanwhile, roller guides 111 corresponding to the pair of left and right rollers 464 are provided on the left and right inner wall portions of the outer housing 11. The roller guides 111 restrict upward and downward movement of the rollers 464. The rollers 464 arranged within the roller guides 111 roll in the front-rear direction along the roller guides 111. The rollers 464 come into contact with the roller guides 111, thereby restricting the rotation of the screw shaft 46 around the drive axis A1 caused by the rotation of the nut 41.

[0044] 3, a magnet holder 485 is fixed to the upper side of the rear end of the screw shaft 46. A magnet 486 is attached to the upper end of the magnet holder 485. The magnet 486 is an example of a "detection target." The magnet 486 is integrated with the screw shaft 46 and moves in the front-rear direction together with the movement of the screw shaft 46 in the front-rear direction.

[0045] The outer housing 11 is provided with a position detection mechanism 48 capable of detecting the magnet 486. The position detection mechanism 48 includes a first sensor 481 and a second sensor 482. The second sensor 482 is disposed rearward of the first sensor 481. The first sensor 481 and the second sensor 482 are, for example, magnetic field detection sensors, and in this embodiment, are Hall sensors equipped with Hall elements. The first sensor 481 is an example of a "braking position detection unit," and the second sensor 482 is an example of a "rear braking position detection unit." The first sensor 481 and the second sensor 482 are electrically connected to the controller 156 (see FIG. 6 ) via electric wires (not shown). When the first sensor 481 and the second sensor 482 detect the magnet 486 disposed within their detection ranges, they output predetermined detection signals to the controller 156. In this embodiment, the detection results of the first sensor 481 and the second sensor 482 are used by the controller 156 to control the drive of the motor 2.

[0046] As shown in Figures 3 and 4, an extension shaft 47 is connected and fixed to the rear end of the screw shaft 46 so as to be coaxial with the screw shaft 46. The extension shaft 47 is integrated with the screw shaft 46. Hereinafter, the integrated screw shaft 46 and extension shaft 47 will be collectively referred to as the "drive shaft 460." The drive shaft 460 has a through hole 461 that passes through the drive shaft 460 along the drive axis A1. The diameter of the through hole 461 is set to be slightly larger than the maximum diameter of the shank 911 of the fastener 9 that can be used with the fastening tool 1.

[0047] An opening 114 that connects the inside and outside of the outer housing 11 is formed on the drive shaft A1 at the rear end of the outer housing 11. A cylindrical guide sleeve 117 is fixed to the front side of the opening 114. The inner diameter of the guide sleeve 117 is approximately equal to the outer diameter of the extension shaft 47. The rear end of the extension shaft 47 is disposed within the guide sleeve 117 when the threaded shaft 46 is disposed in the initial position shown in FIGS. 3 and 4. When the threaded shaft 46 is moved rearward from the initial position as the nut 41 is rotated, the extension shaft 47 moves rearward within the guide sleeve 117.

[0048] 3 and 4, a container connecting portion 113 is provided at the rear end portion of the outer housing 11. The container connecting portion 113 is configured to allow a collection container 7 for collecting broken shaft portions 911 to be attached / detached. A user can attach the collection container 7 to the outer housing 11 via the container connecting portion 113 so that the opening 114 and the internal space of the collection container 7 are in communication with each other.

[0049] 5, the nose portion 16 includes a cylindrical anvil 161 configured to be able to come into contact with the collar 95 of the fastener 9, and a pin gripping portion 165 configured to be able to grip the shank 911 of the fastener 9. The anvil 161 is detachably connected to the front end portion of the housing 10 via a predetermined connecting member. The pin gripping portion 165 is held coaxially within the anvil 161 so as to be able to move relative to the anvil 161 along the drive axis A1.

[0050] The pin gripping portion 165 is integrally connected to the screw shaft 46 via a connecting member 49. This forms a passage 70 that extends along the drive axis A1 from the tip of the pin gripping portion 165 to the opening 114 of the outer housing 11. The shaft portion 911 separated from the fastener 9 passes through the passage 70 and is stored in the collection container 7.

[0051] 2, a trigger 151 is provided on the front side of the upper end of the handle 15. A switch 152 that can be switched between an on state and an off state in response to pressing of the trigger 151 is housed inside the handle 15 behind the trigger 151.

[0052] The lower end of the handle 15 is formed in a rectangular box shape and constitutes a controller housing portion 155. A circuit board 150 is housed inside the controller housing portion 155. As will be described later, the circuit board 150 is equipped with a controller 156 that controls the operation of the fastening tool 1, a three-phase inverter 201, a current detection amplifier 205, and the like. An operation portion 157 is provided at the top of the controller housing portion 155, into which various pieces of information can be input in response to external operations by the user.

[0053] When trigger 151 is pressed, motor 2 is driven, and drive mechanism 4 is driven via motor 2. When pin gripping portion 165 gripping shank 911 of fastener 9 moves rearward relative to anvil 161 along drive axis A1, pin 91 is pulled rearward relative to collar 95. When breakable fastener 9 shown in FIG. 1 is used, collar 95 deforms and crimps onto shank 911 of pin 91, and working materials W1 and W2 are clamped between head 915 of pin 91 and collar 95, after which shank 911 breaks at small diameter portion 913 and separates, completing the fastening of working materials W1 and W2.

[0054] In this way, the fastening tool 1 of this embodiment is configured to perform the fastening process of fastening the work material with the fastener 9 by having the drive mechanism 4 move the pin gripping portion 165 from the front initial position to the rear stop position and then return it to the initial position, which constitutes one cycle.

[0055] A4. Electrical configuration of fastening tool 1: As shown in FIG. 6, the fastening tool 1 includes a three-phase inverter 201, a Hall sensor 203, and a controller 156. The three-phase inverter 201 includes a three-phase bridge circuit using six semiconductor switching elements. The three-phase inverter 201 switches each of the switching elements of the three-phase bridge circuit in accordance with a duty ratio indicated by a control signal from the controller 156. As a result, a drive pulse corresponding to the duty ratio is supplied to the motor 2. The Hall sensor 203 includes three Hall elements arranged corresponding to each phase of the motor 2. The Hall sensor 203 outputs a signal indicating the rotation angle of the rotor 23 to the controller 156.

[0056] The controller 156 is electrically connected to a current detection amplifier 205. The current detection amplifier 205 converts the drive current of the motor 2 into a voltage using a shunt resistor, and outputs the amplified signal to the controller 156.

[0057] 7, the controller 156 is configured with a computer including a CPU 560 as a processor, memory 566 including ROM, RAM, etc., an interface circuit 568, and a timer (not shown), etc. These are connected to each other via an internal bus 565 so as to enable bidirectional communication. An external device OD including the switch 152, operation unit 157, first sensor 481, second sensor 482, and three-phase inverter 201 shown in FIG. 6 is connected to the interface circuit 568.

[0058] The memory 566 stores programs for executing the functions realized by the fastening tool 1 according to this embodiment. As shown in Fig. 7, the CPU 560 reads and executes the programs stored in the memory 566, causing the controller 156 to function as a motor control unit 562 and a shaft position acquisition unit 564. The shaft position acquisition unit 564 is an example of a "position acquisition unit."

[0059] The motor control unit 562 controls the driving of the motor 2 based on a signal output from the external device OD. In this embodiment, the motor control unit 562 can switch the moving direction and moving speed of the screw shaft 46 by controlling the driving of the motor 2. The motor control unit 562 controls the supply of electricity to the motor 2 via the three-phase inverter 201 based on a signal input from, for example, the Hall sensor 203. As a result, the rotation speed of the motor 2 is controlled, and the moving speed of the screw shaft 46 is switched. In this embodiment, PWM control is used to control the rotation speed.

[0060] The motor control unit 562 can switch the rotation direction of the rotor 23 of the motor 2, i.e., the rotation direction of the motor shaft 25, between forward and reverse rotation. "Forward rotation" refers to a rotation direction that moves the screw shaft 46 of the drive mechanism 4 backward relative to the housing 10, while "reverse rotation" refers to a rotation direction that moves the screw shaft 46 of the drive mechanism 4 forward relative to the housing 10. When the trigger 151 receives a pressing operation by the user and turns on the switch 152, the motor control unit 562 drives the motor 2 to rotate the nut 41 forward, thereby moving the screw shaft 46 backward. When the trigger 151 receives a release operation by the user and turns off the switch 152, the motor control unit 562 drives the motor 2 to rotate the nut 41 backward, thereby moving the screw shaft 46 forward. This configuration allows the user to switch between forward and backward movement of the screw shaft 46 simply by operating the trigger 151.

[0061] The shaft position acquisition unit 564 acquires the relative position of the drive mechanism 4 in the front-rear direction with respect to the housing 10 based on a signal output from the external device OD. In this embodiment, the shaft position acquisition unit 564 acquires the relative position of the screw shaft 46 of the drive mechanism 4 (hereinafter simply referred to as the "position of the screw shaft 46"). In this embodiment, the shaft position acquisition unit 564 acquires the position of the screw shaft 46 based on the detection results of the first sensor 481 and the second sensor 482, the rotation speed (rotation angle) of the motor 2 acquired from the Hall sensor 203, the number of drive pulses supplied to the motor 2, the driving time of the motor 2, etc., or by calculation using this information. Note that the "rotation speed of the motor 2" includes the rotation speed of the motor shaft 25 and the rotation speed of the rotor 23. The "acquisition of the position of the screw shaft 46" includes estimation of the position of the screw shaft 46 by calculation, etc.

[0062] A5. Relationship between the forward and backward position of the screw shaft 46 and the drive control of the motor 2: 8, the relationship between the drive control of the motor 2 executed by the fastening tool 1 of the present disclosure and the position of the screw shaft 46 in the front-rear direction will be described. The shaft position acquisition unit 564 acquires the position of the screw shaft 46 in the front-rear direction using the detection results of the first sensor 481 and the second sensor 482 and the number of rotations of the motor 2 acquired from the Hall sensor 203. The motor control unit 562 executes drive control of the motor 2 corresponding to the acquired position of the screw shaft 46 in the front-rear direction.

[0063] As shown in the lower part of Figure 8, an arrow P indicates the direction of movement of the screw shaft 46 and the magnet 486 in one cycle. In this embodiment, in one cycle of the fastening process of the fastener 9, the screw shaft 46 moves from a front initial position PS to a rear stop position PE, and then moves from the stop position PE to the initial position PS. As described above, the magnet 486 is integral with the screw shaft 46, and therefore the positions of the screw shaft 46 and the pin gripping portion 165 correspond to the position of the magnet 486. In the following description, for convenience of explanation, the same symbol indicating the position of the magnet 486 may be used to indicate the position of the screw shaft 46.

[0064] 8 schematically shows the detection range R1 of the first sensor 481, the detection range R2 of the second sensor 482, and the movement range R3 of the magnet 486. When the screw shaft 46 is disposed at the initial position PS, the magnet 486 is included in the detection range R1 of the first sensor 481. Note that, for example, if the screw shaft 46 does not return accurately to the initial position PS when one cycle of the fastening process is completed, the pin gripping portion 165 may not be able to properly grip the pin 91. For this reason, it is preferable to stop the screw shaft 46 as accurately as possible at the initial position PS.

[0065] As shown in the center of Fig. 8, when the screw shaft 46 is disposed at the initial position PS, the first sensor 481 detects the magnet 486 and outputs a detection signal to the controller 156. When the motor 2 is driven and the screw shaft 46 moves rearward, the magnet 486 reaches a non-detection position PD where the magnet 486 leaves the detection range R1. The rearward movement of the screw shaft 46 is also referred to as "rearward movement." At the non-detection position PD, the output of the detection signal from the first sensor 481 switches from on to off.

[0066] When the screw shaft 46 moves further rearward from the non-detection position PD, the magnet 486 reaches a rear detection position PB where it enters the detection range R2 of the second sensor 482. At the rear detection position PB, the output of the detection signal from the second sensor 482 switches from OFF to ON. The rear detection position PB is an example of a "rear braking position." When the output of the detection signal from the first sensor 481 and the second sensor 482 is ON, the magnet 486 is detected, and when it is OFF, the magnet 486 is not detected. The ON state of the output of the detection signal from the first sensor 481 and the second sensor 482 is also referred to as a "detection state," and the OFF state is also referred to as a "non-detection state."

[0067] When the magnet 486 reaches the rear detection position PB and a detection signal from the second sensor 482 is detected, the motor control unit 562 executes control to brake the motor 2. The screw shaft 46 moves rearward from when braking begins until the motor 2 completely stops. When the motor 2 completely stops, the magnet 486 stops at a stop position PE within the detection range R2. When the screw shaft 46 is located at the stop position PE, the second sensor 482 outputs a detection signal. By stopping the driving of the motor 2 using the detection result from the second sensor 482, it is possible to detect the screw shaft 46 at the rear detection position PB using a simpler method than when estimating the position of the screw shaft 46 from the rotation speed of the motor 2.

[0068] In this embodiment, the shaft position acquisition unit 564 estimates the position of the screw shaft 46 using the rotation speed of the motor 2 acquired from the Hall sensor 203. The upper part of Fig. 8 shows the correspondence between the rotation speed of the motor 2 acquired by the shaft position acquisition unit 564 and the position of the magnet 486. In the example of Fig. 8, the cumulative rotation speed of the forward rotation of the motor 2 is shown. Specifically, the rotation speed of the motor 2 increases as the screw shaft 46 moves rearward and decreases as the screw shaft 46 moves forward.

[0069] In this embodiment, as shown by position CD in the upper part of Fig. 8, the shaft position acquisition unit 564 starts counting the number of rotations of the motor 2 from the timing when the screw shaft 46 reaches the non-detection position PD and the output of the detection signal from the first sensor 481 switches from ON to OFF. This configuration makes it possible to suppress the influence of variations in the initial position PS on the counting of the number of rotations of the motor 2. Therefore, the accuracy of estimating the position of the screw shaft 46 can be improved compared to when counting the number of rotations of the motor 2 is started from the initial position PS.

[0070] As indicated by the arrow DD in the upper part of Figure 8, when the switch 152 is turned off by releasing the trigger 151, the threaded shaft 46 moves forward toward the initial position PS. The forward movement of the threaded shaft 46 is also referred to as "forward movement." The forward movement of the threaded shaft 46 can start at any position between the initial position PS and the stop position PE.

[0071] The target speed V1 of the screw shaft 46 when it moves forward can be set arbitrarily. In this embodiment, the target speed V1 is the maximum speed of the screw shaft 46 that can be achieved by the motor 2. The target speed V1 is an example of a "first speed." When the screw shaft 46 moves forward from the stop position PE, the magnet 486 leaves the detection range R2, and the output of the detection signal from the second sensor 482 switches from on to off. When the screw shaft 46 moves further forward, the magnet 486 reaches the deceleration position P1.

[0072] The deceleration position P1 is a position behind the initial position PS. The deceleration position P1 is set in advance, for example, based on the results of a previous experiment, so as to be a position that can improve the positional accuracy of the screw shaft 46 that is stopped at the initial position PS. For example, when the screw shaft 46 starts moving forward from the stop position PE, the deceleration position P1 is set to be a position that is 1.0 mm to 5.0 mm away from a braking position P2, which will be described later.

[0073] In this embodiment, the deceleration position P1 is set based on the rotation speed of the motor 2. That is, the shaft position acquisition unit 564 determines whether the magnet 486 has reached the deceleration position P1 based on the rotation speed of the motor 2. With this configuration, a detection unit for detecting the magnet 486 at the deceleration position P1 can be omitted, and an increase in the number of parts of the fastening tool 1 can be suppressed. Furthermore, the position of the deceleration position P1 can be set and changed more easily than in the case where a detection unit is provided.

[0074] As shown by position C1 in the upper part of Fig. 8, in this embodiment, the deceleration position P1 is set to a position where the rotational speed of the motor 2 reaches a predetermined rotational speed TH after the screw shaft 46 starts moving forward. The rotational speed TH of the motor 2 from the stop position PE, where the screw shaft 46 starts moving forward, to the deceleration position P1 is configured to be less by a predetermined rotational speed THb than the rotational speed THa of the motor 2 from the non-detection position PD, where counting of the rotational speed of the motor 2 starts when the screw shaft 46 moves backward, to the stop position PE. When the screw shaft 46 starts moving forward from the stop position PE, the deceleration position P1 is set to be a distance rearward of the non-detection position PD corresponding to the rotational speed THb.

[0075] At the timing when the screw shaft 46 starts to move forward, the shaft position acquisition unit 564 starts counting the number of rotations of the motor 2. When the number of rotations of the motor 2 reaches a predetermined number of rotations TH, the shaft position acquisition unit 564 determines that the screw shaft 46 has reached the deceleration position P1.

[0076] When the screw shaft 46 reaches the deceleration position P1, the motor control unit 562 controls the motor 2 to switch the speed of the screw shaft 46 to a target speed V2 that is slower than the target speed V1. In this embodiment, the motor control unit 562 reduces the rotational speed of the motor 2 so that the moving speed of the screw shaft 46 becomes approximately 50% of the target speed V1.

[0077] The target speed V2 is preferably set to a speed that is 50% to 70% of the target speed V1 in order to improve the accuracy of the stopping position of the screw shaft 46. The target speed V2 is an example of a "second speed." In this embodiment, the motor control unit 562 reduces the number of rotations of the motor 2 per unit time by PWM control that changes the duty ratio output to the motor 2. By using PWM control, the rotation speed of the motor 2 can be switched with high precision, and the moving speed of the screw shaft 46 can also be switched with high precision.

[0078] When the screw shaft 46 moves further forward from the deceleration position P1, it reaches a braking position P2 where the output of the detection signal from the first sensor 481 switches from OFF to ON. The braking position P2 is substantially the same position as the non-detection position PD. When the output of the detection signal from the first sensor 481 switches from OFF to ON, the shaft position acquisition unit 564 determines that the screw shaft 46 has reached the braking position P2.

[0079] When the lead screw shaft 46 reaches the braking position P2, the motor control unit 562 brakes the motor 2, and the lead screw shaft 46 is braked. Even after the motor 2 is braked, the lead screw shaft 46 continues to move forward until the motor 2 comes to a complete stop, and then stops at the initial position PS. In this embodiment, the motor control unit 562 stops the motor 2 by a short-circuit brake that short-circuits the terminals of the motor 2. This configuration can shorten the stopping time of the motor 2. Furthermore, the braking distance of the lead screw shaft 46 can be shortened, and variation in the stopping position of the lead screw shaft 46 can be suppressed. The short-circuit brake includes a three-phase short-circuit brake and a two-phase short-circuit brake.

[0080] A6. Motor 2 drive control: 9 to 11, the flow of drive control of motor 2 in one cycle of the fastening process of fastener 9 will be described. The flow shown in FIG. 9 starts with trigger 151 released and screw shaft 46 positioned at initial position PS. In the following description, each "step" in the process will be abbreviated as "S."

[0081] In S10, the motor control unit 562 waits for the switch 152 to be turned on by pressing the trigger 151. When the switch 152 is turned on by pressing the trigger 151 (S10: YES), the motor control unit 562 proceeds to S20 and rotates the motor 2 in the forward direction to move the screw shaft 46 backward. For example, the motor control unit 562 controls the movement speed of the screw shaft 46 during the backward movement to become the target speed V1.

[0082] In S30, the shaft position acquisition unit 564 monitors the output of the detection signal from the first sensor 481. When the output of the detection signal from the first sensor 481 switches from ON to OFF (S30: YES), the shaft position acquisition unit 564 determines that the screw shaft 46 has reached the non-detection position PD and proceeds to S40. In S40, the shaft position acquisition unit 564 starts counting the number of rotations of the motor 2.

[0083] In S50, the shaft position acquisition unit 564 monitors the output of the detection signal from the second sensor 482. If the output of the detection signal from the second sensor 482 is OFF, the shaft position acquisition unit 564 determines that the rear detection position PB has not been reached (S50: NO), and proceeds to S52. In S52, the motor control unit 562 monitors whether the switch 152 is turned OFF by the release operation of the trigger 151. If the switch 152 is turned OFF (S52: YES), the motor control unit 562 proceeds to S60. If the switch 152 is not turned OFF within a predetermined time (S52: NO), the motor control unit 562 returns the process to S50.

[0084] In S50, when the output of the detection signal from the second sensor 482 switches from OFF to ON (S50: YES), the shaft position acquisition unit 564 determines that the screw shaft 46 has reached the rear detection position PB. In S60, the motor control unit 562 executes control to brake the motor 2. When the rotation speed of the motor 2 becomes zero due to braking of the motor 2, the screw shaft 46 stops at the stop position PE. Note that in this embodiment, when the screw shaft 46 moves rearward, the motor control unit 562 brakes the motor 2 by stopping the supply of electricity to the motor 2 (setting the duty ratio to zero). The motor control unit 562 may also stop the motor 2 by short-circuit braking.

[0085] The flow shown in FIG. 10 starts when the screw shaft 46 moves backward while the trigger 151 is being pressed, or when the screw shaft 46 is stopped at the stop position PE while the trigger 151 is being pressed.

[0086] In S110, the motor control unit 562 waits for the switch 152 to be switched from on to off by the release operation of the trigger 151. When the switch 152 is turned off (S110: YES), the motor control unit 562 shifts the process to S120 and rotates the motor 2 in the reverse direction to move the screw shaft 46 forward. The motor control unit 562 controls the moving speed of the screw shaft 46 to the target speed V1. In S130, the shaft position acquisition unit 564 starts counting the number of rotations of the motor 2. Note that the processes of S130 and S120 may be executed either first or simultaneously.

[0087] In S140, the shaft position acquisition unit 564 checks whether the screw shaft 46 has reached the deceleration position P1. Specifically, the shaft position acquisition unit 564 monitors the rotation speed of the motor 2, and checks whether the count result of the rotation speed of the motor 2, which is started from S130, has reached the rotation speed TH. If the rotation speed of the motor 2 has not reached the rotation speed TH (S140: NO), the shaft position acquisition unit 564 proceeds to S142.

[0088] In S142, the shaft position acquisition unit 564 monitors the output of the detection signal from the first sensor 481 and checks whether the brake position P2 has been reached. For example, during rearward movement, if the trigger 151 is released before the screw shaft 46 reaches the stop position PE, the screw shaft 46 may reach the brake position P2 before the rotation speed of the motor 2 reaches the rotation speed TH.

[0089] If the output of the detection signal from the first sensor 481 is OFF (S142: NO), the shaft position acquisition unit 564 determines that the screw shaft 46 has not reached the braking position P2, and returns the process to S140. If the output of the detection signal from the first sensor 481 is switched from OFF to ON (S142: YES), the shaft position acquisition unit 564 determines that the screw shaft 46 has reached the braking position P2, and shifts the process to S170.

[0090] In S140, when the rotation speed of the motor 2 reaches the rotation speed TH (S140: YES), the shaft position acquisition unit 564 determines that the screw shaft 46 has reached the deceleration position P1, and proceeds to S150. In S150, the motor control unit 562 starts decelerating the rotation speed of the motor 2 so that the moving speed of the screw shaft 46 changes from the target speed V1 to the target speed V2.

[0091] In S160, the shaft position acquisition unit 564 monitors the output of the detection signal from the first sensor 481 and checks whether the screw shaft 46 has reached the braking position P2. If the screw shaft 46 has not reached the braking position P2 (S160: NO), the shaft position acquisition unit 564 returns the process to S160. If the output of the detection signal from the first sensor 481 switches from OFF to ON (S160: YES), the shaft position acquisition unit 564 determines that the screw shaft 46 has reached the braking position P2 and proceeds to S170. In S170, the motor control unit 562 brakes the motor 2 using a short-circuit brake, stops the screw shaft 46, and ends the process.

[0092] 11 shows an example in which the screw shaft 46 moves backward to the stop position PE, and then moves forward from the stop position PE to the initial position PS. At time t1, the trigger 151 is pressed to turn on the switch 152. The motor control unit 562 drives the motor 2 in the forward direction so that the rotation speed of the motor 2 becomes the target speed V1. At time t2, the screw shaft 46 reaches the non-detection position PD, and the detection signal from the first sensor 481 switches from on to off. The shaft position acquisition unit 564 starts counting the number of rotations of the motor 2.

[0093] At time t3, the screw shaft 46 reaches the rear detection position PB, and the detection signal from the second sensor 482 switches from OFF to ON. The motor control unit 562 brakes the motor 2. At time t4, the screw shaft 46 stops at the stop position PE, and the rearward movement of the screw shaft 46 is completed.

[0094] At time t5, the trigger 151 is released, turning off the switch 152. The motor control unit 562 drives the motor 2 in reverse rotation so that the movement speed of the screw shaft 46 becomes the target speed V1. The shaft position acquisition unit 564 starts counting the number of rotations of the motor 2. At time t6, the number of rotations of the motor 2 reaches the number of rotations TH, and the motor control unit 562 drives the motor 2 to decelerate the movement speed of the screw shaft 46 toward the target speed V2.

[0095] At time t7, the lead screw 46 reaches the braking position P2, and the detection signal from the first sensor 481 switches from OFF to ON. The motor control unit 562 brakes the motor 2 using a short-circuit brake. At time t8, the lead screw 46 stops at the initial position PS, and the forward movement of the lead screw 46 is completed.

[0096] As described above, according to the fastening tool 1 of this embodiment, when the screw shaft 46 reaches the deceleration position P1 during its forward movement, the movement speed of the screw shaft 46 is decelerated from the target speed V1 to the target speed V2 by PWM control. Since the driving of the motor 2 is stopped after the movement speed of the screw shaft 46 is decelerated, it is possible to suppress or prevent variation in the stop position when the screw shaft 46 stops at the initial position PS during the forward movement. Therefore, it is possible to suppress or prevent the pin gripping portion 165 from being unable to properly grip the pin 91.

[0097] In the fastening tool 1 of this embodiment, the shaft position acquisition unit 564 determines that the deceleration position P1 has been reached when the rotation speed of the motor 2 acquired during the forward movement of the screw shaft 46 reaches the rotation speed TH. Therefore, it is not necessary to provide a component for detecting the deceleration position P1, and the deceleration position P1 can be detected with a small number of parts. Furthermore, the deceleration position P1 can be easily set or changed.

[0098] B. Second embodiment: 12, the drive control of the motor 2 executed by the fastening tool 1 according to the second embodiment differs from that of the first embodiment in that S144 to S152 are provided instead of S140, S142, and S150, but the other configurations are the same as those of the first embodiment. In this embodiment, the moving speed of the screw shaft 46 is decelerated when it reaches the target speed V1 during forward movement.

[0099] In S144, the motor control unit 562 monitors the rotation speed of the motor 2 and checks whether the moving speed of the screw shaft 46 has reached the target speed V1. When the rotation speed of the motor 2 reaches a predetermined value and the moving speed of the screw shaft 46 has reached the target speed V1 (S144: YES), the shaft position acquisition unit 564 transitions the process to S146.

[0100] In S146, the shaft position acquisition unit 564 calculates the distance from the position of the screw shaft 46 at the timing when the target speed V1 is reached (hereinafter also referred to as the "arrival position") to the braking position P2. In this embodiment, the distance from the arrival position to the braking position P2 is indicated by the number of rotations of the motor 2 required to move from the arrival position to the braking position P2. In this embodiment, counting the number of rotations of the motor 2 starts from the non-detection position PD, which is approximately the same as the braking position P2, so the shaft position acquisition unit 564 can acquire the distance from the arrival position to the braking position P2 (the number of rotations of the motor 2) by acquiring the number of rotations of the motor 2 at the arrival position.

[0101] In S148, the motor control unit 562 calculates a negative acceleration using the distance from the arrival position to the braking position P2 (the number of rotations of the motor 2). "Negative acceleration" refers to an acceleration that decelerates an object. In this embodiment, the motor control unit 562 calculates the negative acceleration as a fixed value using so-called negative constant-acceleration linear motion, in which the movement speed of the screw shaft 46 at the arrival position is set to a target speed V1 and the movement speed at the braking position P2 is set to a target speed V2. By setting the acceleration to a fixed value, the cost of calculating the acceleration can be reduced. In S152, the motor control unit 562 drives the motor 2 in accordance with the calculated negative acceleration as a fixed value, and decelerates the movement speed of the screw shaft 46 until it reaches the braking position P2. Note that the acceleration is not limited to a constant and may be a variable.

[0102] As shown in FIG. 13 , at time t5, similarly to the first embodiment, by releasing the trigger 151, the motor control unit 562 drives the motor 2 in reverse rotation so that the movement speed of the screw shaft 46 becomes the target speed V1. When the rotation speed of the motor 2 reaches the target speed V1 at time t6b, the shaft position acquisition unit 564 acquires the reached position and calculates the distance from the reached position to the braking position P2 (the number of rotations TH2 of the motor 2). The motor control unit 562 calculates the negative acceleration dV using the number of rotations TH2 of the motor 2 from the reached position to the braking position P2. The motor control unit 562 drives the motor 2 so that the movement speed of the screw shaft 46 is decelerated in accordance with the negative acceleration dV.

[0103] According to the fastening tool 1 of this embodiment, the motor control unit 562 decelerates the movement speed by the calculated negative acceleration dV and then stops driving the motor 2. As in the first embodiment, the movement speed of the screw shaft 46 is decelerated and then driving of the motor 2 is stopped, so that it is possible to suppress or prevent variation in the position at which the screw shaft 46 stops at the initial position PS during forward movement of the screw shaft 46.

[0104] In the fastening tool 1 of this embodiment, the motor control unit 562 calculates the negative acceleration dV using the distance from the arrival position to the braking position P2, and drives the motor 2 to decelerate the movement speed of the screw shaft 46 by the calculated negative acceleration dV. Because the negative acceleration is calculated according to the arrival position, even if the arrival position fluctuates due to, for example, differences in the timing of the release operation of the trigger 151, the movement speed at the braking position P2 is switched to the target speed V2. Therefore, it is possible to suppress or prevent variation in the stopping position of the screw shaft 46 at the initial position PS due to fluctuations in the arrival position.

[0105] C. Other Embodiments: (C1) In the first embodiment described above, the deceleration position P1 is set to a position where the rotation speed of the motor 2 reaches a predetermined rotation speed TH after the screw shaft 46 starts to move forward. In contrast, the deceleration position P1 may be set to a position a predetermined distance (the rotation speed of the motor 2) behind the initial position PS. In this case, the movement speed of the screw shaft 46 can be decelerated at a fixed position regardless of the position where the screw shaft 46 starts to move forward.

[0106] (C2) In the second embodiment described above, the motor control unit 562 switches the rotation speed of the motor 2 per unit time using PWM control that changes the duty ratio output to the motor 2. In contrast, the motor control unit 562 may switch the movement speed of the screw shaft 46 using constant rotation speed control of the motor 2. "Constant rotation speed control" refers to control that adjusts the drive voltage of the motor 2 so that the rotation speed of the motor shaft 25 per unit time is at or below a predetermined target rotation speed. Constant rotation speed control makes it possible to switch the movement speed of the screw shaft 46 with high precision. For example, the motor control unit 562 may execute constant rotation speed control of the motor 2 so that the target rotation speed of the motor 2 is between 50% and 75% of the target rotation speed when moving the motor 2 forward from the stop position PE toward the initial position PS.

[0107] (C3) The configurations of the motor 2, the transmission mechanism 3, and the drive mechanism 4 can be modified as appropriate. For example, the motor 2 may be a brushed motor or an AC motor. For example, the number of planetary gear mechanisms of the planetary reducer 31 or the arrangement of the intermediate shaft 33 may be changed. For example, instead of the ball screw mechanism 40 including the nut 41 and the screw shaft 46 that engages with the nut via a ball, the drive mechanism 4 may be a feed screw mechanism including a nut with a female thread formed on its inner periphery and a screw shaft with a male thread formed on its outer periphery and directly screwed into the nut. In the ball screw mechanism 40, the screw shaft 46 may be rotatably supported and its movement in the front-rear direction restricted, and the nut 41 may be configured to move in the front-rear direction as the screw shaft 46 rotates. In this case, the pin gripper 165 is directly or indirectly connected to the nut 41.

[0108] (C4) In each of the above embodiments, magnetic field detection sensors are used for the first sensor 481 and the second sensor 482, but other types of sensors (for example, optical sensors such as photointerrupters) or mechanical switches may also be used.

[0109] (C5) In each of the above embodiments, the controller 156 is configured as a computer including a CPU, ROM, RAM, etc. Alternatively, the controller may be configured as a programmable logic device such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The drive control process in each of the above embodiments may be implemented by the CPU executing a program stored in ROM. In this case, the program may be pre-stored in the ROM of the controller 156, or, if the controller 156 includes a non-volatile memory, may be stored in the non-volatile memory. Alternatively, the program may be recorded on an external storage medium from which data can be read (e.g., a USB memory). The drive control process in the above embodiments and modifications may be distributed among multiple control circuits.

[0110] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0111] 1...fastening tool, 2...motor, 3...transmission mechanism, 4...drive mechanism, 7...collection container, 9...fastener, 10...housing, 11...outer housing, 13...inner housing, 15...handle, 16...nose portion, 20...motor main body portion, 21...stator, 23...rotor, 25...motor shaft, 27...fan, 30...reduction gear housing, 31...planetary reducer, 33...intermediate shaft, 35...nut drive gear, 40...ball screw mechanism, 41...nut, 46...screw shaft, 47...extension shaft, 48...position detection mechanism, 49...connecting member, 70...passage, 91...pin, 95...collar, 111...roller guide, 113...container connection portion, 114...opening, 117...guide sleeve, 150...circuit board, 151...trigger, 152...switch, 155...controller roller housing section, 156...controller, 157...operation section, 158...battery mounting section, 159...battery, 161...anvil, 165...pin gripping section, 201...three-phase inverter, 203...hall sensor, 205...current detection amplifier, 311...sun gear, 313...carrier, 411...driven gear, 412...radial bearing, 460...drive shaft, 461...through hole, 463...roller holding section, 464...roller, 481...first sensor, 482...second sensor, 485...magnet holding section, 486...magnet, 560...CPU, 562...motor control section, 564...shaft position acquisition section, 565...internal bus, 566...memory, 568...interface circuit, 911...shaft section, 913...small diameter section, A1...drive shaft, A2...rotating shaft, OD...external device, W1, W2...working material

Claims

1. A fastening tool for fastening work materials via a fastener having a pin and a cylindrical portion, a motor including a motor shaft; a housing that accommodates the motor; a pin gripping portion configured to grip the pin; a drive mechanism connected to the pin gripping portion, the drive mechanism being configured to be able to perform a rearward movement from an initial position to the rear along a drive axis that defines a front-rear direction of the fastening tool by forward rotation of the motor shaft, and a forward movement from the rear to the initial position along the drive axis by reverse rotation of the motor shaft; a position acquisition unit configured to acquire a relative position of the drive mechanism with respect to the housing in the front-rear direction; a motor control unit configured to control the drive of the motor and to be able to switch the movement direction and movement speed of the drive mechanism; The motor control unit commencing the forward movement of the drive mechanism so that the movement speed becomes a first speed; When the acquired relative position reaches a deceleration position that is behind the initial position during the forward movement, the movement speed is decelerated to a second speed that is slower than the first speed by PWM control that changes a duty ratio output to the motor; When the acquired relative position reaches a predetermined braking position which is ahead of the deceleration position and behind the initial position, driving of the motor is stopped. Fastening tools.

2. A fastening tool for fastening work materials via a fastener having a pin and a cylindrical portion, a motor including a motor shaft; a housing that accommodates the motor; a pin gripping portion configured to grip the pin; a drive mechanism connected to the pin gripping portion, the drive mechanism being configured to be able to perform a rearward movement from an initial position to the rear along a drive axis that defines a front-rear direction of the fastening tool by forward rotation of the motor shaft, and a forward movement from the rear to the initial position along the drive axis by reverse rotation of the motor shaft; a position acquisition unit configured to acquire a relative position of the drive mechanism with respect to the housing in the front-rear direction; a motor control unit configured to control the drive of the motor and to be able to switch the movement direction and movement speed of the drive mechanism; The motor control unit commencing the forward movement of the drive mechanism so that the movement speed becomes a first speed; When the acquired relative position reaches a deceleration position that is behind the initial position during the forward movement, the movement speed is decelerated to a second speed that is slower than the first speed by a constant rotation speed control that adjusts a drive voltage of the motor so that the rotation speed per unit time of the motor shaft becomes a predetermined target rotation speed; When the acquired relative position reaches a predetermined braking position which is ahead of the deceleration position and behind the initial position, driving of the motor is stopped. Fastening tools.

3. A fastening tool for fastening work materials via a fastener having a pin and a cylindrical portion, a motor including a motor shaft; a housing that accommodates the motor; a pin gripping portion configured to grip the pin; a drive mechanism connected to the pin gripping portion, the drive mechanism being configured to be able to perform a rearward movement from an initial position to the rear along a drive axis that defines a front-rear direction of the fastening tool by forward rotation of the motor shaft, and a forward movement from the rear to the initial position along the drive axis by reverse rotation of the motor shaft; a position acquisition unit configured to acquire a relative position of the drive mechanism with respect to the housing in the front-rear direction; a motor control unit configured to control the drive of the motor and to be able to switch the movement direction and movement speed of the drive mechanism; The motor control unit commencing the forward movement of the drive mechanism so that the movement speed becomes a first speed; determining a negative acceleration so that, when the movement speed reaches the first speed during the forward movement, the movement speed at a braking position a predetermined distance rearward from the initial position becomes a second speed slower than the first speed, and decelerating the movement speed at the determined acceleration; When the acquired relative position reaches the braking position, driving of the motor is stopped. Fastening tools.

4. The fastening tool according to claim 1 or 2, the position acquisition unit acquires a rotation speed of the motor shaft, and acquires the relative position using the acquired rotation speed of the motor shaft. Fastening tools.

5. The fastening tool according to claim 4, the position acquisition unit determines that the deceleration position has been reached when the number of rotations acquired during the forward movement reaches a predetermined number of rotations. Fastening tools.

6. The fastening tool according to claim 4, The number of rotations of the motor shaft from the position where the forward movement starts to the deceleration position is configured to be less by a predetermined number of rotations than the number of rotations of the motor shaft from the position where counting of the number of rotations of the motor shaft starts during the backward movement to the position where the forward movement starts. Fastening tools.

7. The fastening tool according to claim 3, The position acquisition unit acquiring a rotation speed of the motor shaft, and using the acquired rotation speed of the motor shaft, acquiring an arrival position at which the moving speed reaches the first speed; Calculating a distance from the acquired arrival position to the braking position; the motor control unit calculates the acceleration using the calculated distance from the arrival position to the braking position, and decelerates the moving speed by the calculated acceleration. Fastening tools.

8. The fastening tool according to claim 7, the motor control unit decelerates the moving speed at a constant negative acceleration corresponding to the acquired distance from the arrival position to the braking position. Fastening tools.

9. The fastening tool according to any one of claims 4 to 8, a detection target provided on the drive mechanism and moving integrally with the drive mechanism; a braking position detection unit configured to be able to detect the detection object provided in the drive mechanism when the drive mechanism is placed at the braking position, the position acquisition unit starts acquiring the rotation speed of the motor shaft at a timing when the detection result by the braking position detection unit switches from a detection state in which the detection object is detected to a non-detection state in which the detection object is not detected during the backward movement. Fastening tools.

10. A fastening tool according to claim 3 or any one of claims 7 to 9 depending directly or indirectly on claim 3, the motor control unit switches the movement speed by PWM control that changes a duty ratio output to the motor. Fastening tools.

11. A fastening tool according to claim 3 or any one of claims 7 to 9 depending directly or indirectly on claim 3, The motor control unit performing constant rotation speed control to adjust a drive voltage of the motor so that the rotation speed of the motor shaft per unit time becomes a predetermined target rotation speed; The moving speed is switched by switching the target rotation speed. Fastening tools.

12. The fastening tool according to any one of claims 1 to 11, the motor control unit stops the motor by a short-circuit brake that short-circuits terminals of the motor; Fastening tools.

13. The fastening tool according to any one of claims 1 to 12, The drive mechanism includes: a nut that is driven to rotate around the drive shaft by the power of the motor; a shaft coupled to the pin gripping portion, the shaft configured such that the rearward movement is performed by a forward rotation of the motor shaft and the forward movement is performed by a reverse rotation of the motor shaft; Fastening tools.

14. The fastening tool according to any one of claims 1 to 13, a detection target provided on the drive mechanism and moving integrally with the drive mechanism; a rear braking position detection unit configured to detect the detection object provided in the drive mechanism when the drive mechanism is disposed at a rear braking position rearward of the braking position, the motor control unit stops driving the motor when the detection target is detected by the rear braking position detection unit. Fastening tools.

15. The fastening tool according to any one of claims 1 to 14, Further, a trigger capable of receiving a pressing operation and a release operation for releasing the pressing operation is provided, When the trigger receives the pressing operation, the motor control unit drives the motor to rotate the motor shaft in a forward direction, and when the trigger receives the releasing operation, the motor control unit drives the motor to rotate the motor shaft in a reverse direction. Fastening tools.

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