Fastening tool

Abstract

To provide a technique contributing to improvement of positioning accuracy of a pin gripping part in an initial state of a fastening tool.SOLUTION: The fastening tool includes a tool body, a motor, a pin-gripping part configured to move between a foremost position and a rearmost position with respect to the tool body, a first detector configured to detect that the pin-gripping part is in a first detection position, a first contact part configured to move together with the pin-gripping part in a front-rear direction with respect to the tool body, a second contact part provided in the tool body and configured to position the pin-gripping part in the foremost position by coming into contact with the first contact part, a second detector configured to detect contact between the first contact part and the second contact part, and a controller configured to control driving of the motor. The controller is configured to decelerate the motor in response to detection of arrival of the pin-gripping part at the first detection position by the first detector during forward movement of the pin-gripping part, and then stop the motor in response to detection of contact between the first contact part and the second contact part by the second detector.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] SUMMARY The present disclosure relates to a fastening tool configured to fasten workpieces with fasteners. [Background technology]

[0002] Known fastening tools are configured to move a pin gripping portion that grips the pin of a fastener backward from a predetermined position to deform the fastener and fasten the workpiece, and then move the pin gripping portion forward to return to the predetermined position. The initial position of the pin gripping portion (also referred to as the initial position, home position, etc.) is desirably set so that the pin gripping portion can grip the pin with an appropriate force. Therefore, for example, the controller of the fastening tool disclosed in Patent Document 1 decelerates the motor during the reset process of the fastener gripping portion (pin gripping portion) when the fastener gripping portion reaches within a predetermined distance from the predetermined home position. The controller then stops the motor when a Hall sensor detects that the fastener gripping portion has reached the predetermined home position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2024 / 0066587 Summary of the Invention [Problem to be solved by the invention]

[0004] In the fastening tool described above, the Hall sensor decelerates the motor before the fastener gripping portion reaches the home position, reducing the deviation between the home position and the actual position of the fastener gripping portion when the tool is stopped. However, the sensitivity of the Hall sensor varies due to temperature, individual differences, etc., so the actual position of the fastener gripping portion when the tool is stopped can still vary.

[0005] One non-limiting object of the present disclosure is to provide a technique that contributes to improving the positioning accuracy of a pin gripping portion in the initial state of a fastening tool. [Means for solving the problem]

[0006] According to one non-limiting aspect of the present disclosure, there is provided a fastening tool configured to fasten workpieces using a fastener including a pin and a tubular portion, the fastening tool including a tool body, a motor, a pin gripping portion, a first detection device, a first abutment portion, a second abutment portion, a second detection device, and a control device.

[0007] The motor is housed in the tool body. The pin gripping portion is configured to grip a pin. The pin gripping portion is operably connected to the motor and is movable relative to the tool body between a forward-most position and a rearward-most position along a drive shaft that defines a front-to-rear direction of the fastening tool by power from the motor. The first detection device is configured to detect when the pin gripping portion is at a first detection position between the forward-to-rearmost position and the rearward-to-rearmost position in the front-to-rear direction.

[0008] The first abutment portion is configured to move integrally with the pin gripping portion in the front-to-rear direction relative to the tool body. The second abutment portion is provided within the tool body and configured to abut against the first abutment portion as the pin gripping portion moves from the rear to the frontmost position, thereby positioning the pin gripping portion at the frontmost position. The first abutment portion may be a part of the pin gripping portion, or may be a part of a separate member connected to the pin gripping portion. Similarly, the second abutment portion may be a part of the tool body, or may be a part of a separate member connected to the tool body. The second detection device is configured to detect abutment between the first abutment portion and the second abutment portion.

[0009] The control device is configured to control driving of the motor. The pin gripping portion is configured to fasten the work material with the fastener by moving rearward from a forward-most position. The control device is configured to decelerate the motor in response to the first detection device detecting that the pin gripping portion has reached a first detection position during the forward movement of the pin gripping portion, and then stop the motor in response to the second detection device detecting contact between the first abutment portion and the second abutment portion. Note that the control device can be embodied, for example, by at least one processor / processing circuit.

[0010] In the fastening tool of this aspect, when the pin gripping portion moves rearward to perform the fastening operation and then moves forward to return to the forward-most position, the first abutment portion and the second abutment portion abut, the pin gripping portion is positioned at the forward-most position, and the control device stops the motor. In other words, the motor is stopped with the pin gripping portion physically restricted from moving at the forward-most position. This ensures that the pin gripping portion can be returned to the forward-most position. Furthermore, when the first detection device detects that the pin gripping portion has reached the first detection position, which is rearward of the forward-most position, during the forward movement of the pin gripping portion, the control device decelerates the motor. This effectively reduces the impact when the first abutment portion and the second abutment portion collide.

[0011] It is preferable that the control device reduces the rotational speed of the motor to a predetermined speed suitable for reliably suppressing impact at least at the time when the first contact portion and the second contact portion contact each other. For example, the control device may continue to decelerate the motor from the first detection position until the first contact portion and the second contact portion contact each other so that the rotational speed of the motor is equal to or less than the predetermined speed at the time when the first contact portion and the second contact portion contact each other. Alternatively, the control device may complete deceleration before the first contact portion and the second contact portion contact each other. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. [Figure 2] FIG. 2 is a partially enlarged view of FIG. 1 (however, the fastener is not shown). [Figure 3] FIG. 2 is a further enlarged partial view of FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3, showing an initial state in which the motor is stopped. [Figure 5] FIG. 4 is a cross-sectional view taken along line VV in FIG. [Figure 6] 5 is a cross-sectional view corresponding to FIG. 4, showing the state when the pin gripping portion has reached the frontmost position from the rear. [Figure 7] 4 is a cross-sectional view corresponding to FIG. 3, showing a state when the pin gripping portion has reached the first detection position. [Figure 8] 5 is a cross-sectional view corresponding to FIG. 4, showing a state when the pin gripping portion has reached the first detection position. [Figure 9] 4 is a cross-sectional view corresponding to FIG. 3, showing a state when the pin gripping portion has reached the deceleration completion position. [Figure 10] 5 is a cross-sectional view corresponding to FIG. 4, showing a state when the pin gripping portion has reached the deceleration completion position. [Figure 11] FIG. 2 is a block diagram showing an electrical configuration of the fastening tool. [Figure 12] 10 is a flowchart of a first control process performed when a pin gripping portion performs a pulling operation. [Figure 13] 10A and 10B are diagrams illustrating changes in the rotation speed and drive current value of the motor during the fastening process. [Figure 14] 10 is a flowchart of a first control process performed during a return operation of a pin gripping portion. [Figure 15] 10 is a flowchart of a first control process according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] In one non-limiting embodiment of the present disclosure, the control device may be configured to reduce the rotational speed of the motor to a predetermined speed in response to the first detection device detecting that the pin gripping portion has reached the first detection position, and thereafter drive the motor at the predetermined speed until the second detection device detects contact between the first abutment portion and the second abutment portion. According to this embodiment, the rotational speed of the motor can be reliably maintained at a rotational speed appropriate for suppressing impact when the first abutment portion and the second abutment portion contact each other.

[0014] In addition to or instead of the above embodiment, the second detection device may be configured to detect a physical quantity related to the driving state of the motor. When the first contact portion and the second contact portion abut on each other, the movement of the pin gripping portion forward from its forwardmost position is physically prevented, causing a change in the driving state of the motor. Therefore, detecting a physical quantity related to the driving state of the motor is a reasonable method for detecting the abutment between the first contact portion and the second contact portion.

[0015] In addition to or instead of the above embodiment, the second detection device may be configured to detect at least one of the following physical quantities: (i) a motor current value, (ii) a change in the current value, (iii) a rotational speed of the motor, and (iv) a change in the rotational speed. When the first contact portion and the second contact portion come into contact with each other and physically prevent the pin gripping portion from moving forward from its forwardmost position, the motor stops and the load on the motor increases rapidly. Therefore, by using at least one of the above (i) to (iv), it is possible to appropriately detect the contact between the first contact portion and the second contact portion.

[0016] In addition to or instead of the above embodiment, the first detection device may be a magnetic sensor. According to this embodiment, it is possible to detect with a simple mechanism that the pin gripping portion is at the first detection position.

[0017] In addition to or instead of the above embodiment, the motor may be a three-phase brushless motor. The control device may be configured to generate a braking force by shorting terminals of at least two phases, thereby decelerating the motor. According to this embodiment, the magnitude of the braking force can be appropriately adjusted by changing the number of phases to be shorted and / or the short-circuit time.

[0018] In addition to or instead of the above embodiment, the control device may be configured to decelerate the motor by changing the duty ratio for PWM control of the motor. According to this embodiment, the motor can be appropriately decelerated with simple control.

[0019] In addition to or instead of the above embodiment, the rotation speed of the motor after deceleration may be lower than 20% of the rotation speed before deceleration. According to this embodiment, the rotation speed before deceleration can be set relatively high in consideration of work efficiency, while reducing the impact when the first contact portion and the second contact portion collide.

[0020] In addition to or instead of the above embodiment, the rotational speed after deceleration may be set so that the stress caused by the contact between the first contact portion and the second contact portion does not exceed the fatigue limit of the first contact portion and the second contact portion. According to this embodiment, the possibility of damage to the first contact portion and the second contact portion can be effectively reduced.

[0021] In addition to or instead of the above embodiment, the fastening tool may further include a screw feed mechanism operably connected to the motor and the pin gripping portion. The screw feed mechanism may include a nut member and a shaft member. The nut member may be rotatably supported around the drive shaft within the tool body and configured to be rotationally driven by power from the motor. The shaft member may be operably engaged with the nut member so as to move linearly in the forward and backward directions integrally with the pin gripping portion in response to rotation of the nut member. The shaft member may have a rotation prevention portion configured to inhibit rotation around the drive shaft by engaging with the tool body. A portion of the rotation prevention portion may be configured as a first abutment. According to this embodiment, a rational first abutment is realized that utilizes the rotation prevention portion required for the screw feed mechanism used to drive the pin gripping portion.

[0022] In addition to or instead of the above embodiment, the fastening tool may further include a reaction force receiving portion disposed between the nut member and the first abutment portion in the front-rear direction and configured to receive a rearward reaction force acting on the nut member when the shaft member moves forward. A part of the reaction force receiving portion may be configured as the second abutment portion. According to this embodiment, a rational second abutment portion is realized by utilizing the reaction force receiving portion of the nut member.

[0023] In addition to or instead of the above embodiment, the fastening tool may further include a third detection device, a third abutment portion, and a fourth abutment portion. The third detection device may be configured to detect that the pin gripping portion is at a second detection position between the first detection position and the rearmost position in the front-to-rear direction. Note that the third detection device may be a magnetic sensor, similar to the first detection device.

[0024] The third abutment portion may be configured to move integrally with the pin gripping portion in the front-to-rear direction relative to the tool body. The fourth abutment portion may be provided within the tool body and configured to abut against the third abutment portion as the pin gripping portion moves from the front to the rearmost position, thereby positioning the pin gripping portion at the rearmost position. The third abutment portion may be a part of the pin gripping portion, or a part of a separate member connected to the pin gripping portion. Similarly, the fourth abutment portion may be a part of the tool body, or a part of a separate member connected to the tool body. The second detection device may be further configured to detect abutment between the third abutment portion and the fourth abutment portion.

[0025] The control device may be configured to decelerate the motor in response to the third detection device detecting that the pin gripping portion has reached the second detection position while the pin gripping portion is moving rearward, and then to stop rotation of the motor in response to the second detection device detecting contact between the third abutment portion and the fourth abutment portion.

[0026] According to this embodiment, the fastening tool operates in the same manner when the pin gripping portion moves rearward as when the pin gripping portion moves forward. In other words, the fastening operation is performed while the pin gripping portion moves rearward. When the pin gripping portion reaches its rearmost position, the third abutment portion and the fourth abutment portion come into contact with each other, the pin gripping portion is positioned at its rearmost position, and the control device stops the motor. In other words, the motor is stopped with the pin gripping portion's movement physically restricted at its rearmost position. This ensures that the pin gripping portion is positioned at its rearmost position. Furthermore, when the third detection device detects that the pin gripping portion has reached the second detection position, which is forward of the rearmost position, during the rearward movement of the pin gripping portion, the control device decelerates the motor. This effectively reduces the impact when the third abutment portion and the fourth abutment portion collide. The deceleration method for the pin gripping portion during its rearward movement may be substantially the same as or different from the deceleration method for the pin gripping portion during its forward movement.

[0027] Representative and non-limiting embodiments of the present disclosure will be specifically described below with reference to the drawings.

[0028] First Embodiment A fastening tool 1 according to a first embodiment will be described with reference to Figures 1 to 14. The fastening tool 1 is an example of a power tool capable of fastening work materials together using a fastener.

[0029] The fastening tool 1 can selectively use multiple types of fasteners. The fastener 9 shown in Fig. 1 is an example of a fastener that can be used with the fastening tool 1. More specifically, the fastener 9 is an example of a known fastener called a multi-piece swage type fastener.

[0030] The configuration of fastener 9 will be briefly described below. Fastener 9 includes pin 91 and collar 95. Pin 91 includes a shank and a head integrally formed at one end of the shank. Collar 95 is a cylindrical member through which the shank can be inserted. Pin 91 and collar 95 were originally formed as separate bodies. When fastening tool 1 pulls pin 91 in the axial direction relative to collar 95, collar 95 is deformed, and work material W is fastened between the head of pin 91 and collar 95, which is crimped to the shank of pin 91.

[0031] The general configuration of the fastening tool 1 will be described below.

[0032] As shown in FIG. 1, the fastening tool 1 includes a tool body 10 , a nose portion 16 , and a handle 17 .

[0033] The tool body 10 is a hollow body also referred to as a housing. The tool body 10 accommodates the motor 21, the drive mechanism 3, etc. The nose portion 16 includes a cylindrical anvil 161 and a pin gripping portion 165 disposed within the anvil 161. The anvil 161 is fixedly connected to one end of the tool body 10 so as to extend along a predetermined drive axis A1. The pin gripping portion 165 is operably connected to the drive mechanism 3 and is movable along the drive axis A1 relative to the anvil 161. A collection container 19 capable of collecting pintails separated during the fastening process is removably attached to the end of the tool body 10 opposite the anvil 161 in the extension direction of the drive axis A1.

[0034] The handle 17 is a long cylindrical body configured to be gripped by a user. The handle 17 extends in a cantilevered manner from the tool body 10 in a direction intersecting (more specifically, in a direction roughly perpendicular to) the drive axis A1. The handle 17 is provided with a trigger 171 that is pressed (pulled) by the user. A battery 145 is removably attached to the free end of the handle 17. The fastening tool 1 operates using power supplied from the battery 145.

[0035] In the following, for the sake of convenience, the direction of the fastening tool 1 will be defined as the extension direction of the drive axis A1 as the front-rear direction of the fastening tool 1. In the front-rear direction, the side on which the nose portion 16 is located will be defined as the front side, and the opposite side (the side on which the collection container 19 is located) will be defined as the rear side. In addition, the direction perpendicular to the drive axis A1 and corresponding to the longitudinal direction of the handle 17 will be defined as the up-down direction. In the up-down direction, one end of the handle 17 connected to the tool body 10 will be defined as the upper side, and the opposite side (the free end side of the handle 17) will be defined as the lower side. In addition, the direction perpendicular to the front-rear direction and the up-down direction will be defined as the left-right direction.

[0036] When the user engages part of the shank of the pin 91 of the fastener 9 with the opening at the tip of the anvil 161 and presses the trigger 171, the motor 21 is driven. The power of the motor 21 drives the drive mechanism 3, and the pin gripping portion 165 grips the pin 91 and pulls it strongly backward relative to the collar 95, deforming the fastener 9 and fastening the work material W. A part of the shank of the pin 91 (the pintail) is torn off and separated from the fastener 9. The drive mechanism 3 then returns the pin gripping portion 165 to the front, completing the series of operations in the fastening process. Hereinafter, the backward movement of the pin gripping portion 165 will be referred to as the pulling operation, and the forward movement of the pin gripping portion 165 will be referred to as the returning operation.

[0037] The physical configuration of the fastening tool 1 will now be described in detail.

[0038] First, the tool body 10 and the elements disposed therein will be described.

[0039] As shown in FIG. 1 , the tool body 10 includes an outer housing 101 and an inner housing 105. The outer housing 101 is formed in a generally rectangular box shape and extends along the drive axis A1. The inner housing 105 is formed in a generally cylindrical shape and is fixedly held to the outer housing 101 within the front half of the upper half of the outer housing 101. In this embodiment, the outer housing 101 is formed integrally with the handle 17 from resin, while the inner housing 105 is formed from metal.

[0040] As shown in FIG. 2, the tool body 10 mainly houses a motor 21, a drive mechanism 3, and a position detection mechanism 8 inside.

[0041] The motor 21 is housed in the lower rear end of the tool body 10. A three-phase brushless DC motor is used as the motor 21 in this embodiment. The rotation axis of the motor shaft 211 extends below the drive shaft A1 and parallel to the drive shaft A1 (i.e., in the front-to-rear direction). The motor shaft 211 can rotate in two directions: forward and reverse. The forward direction corresponds to the direction in which the screw shaft 45 and the pin gripping portion 165, which will be described later, move rearward. The reverse direction corresponds to the direction in which the screw shaft 45 and the pin gripping portion 165 move forward.

[0042] The drive mechanism 3 is operably connected to the motor 21. The drive mechanism 3 is configured to move the pin 91 of the fastener 9 in the forward and backward directions relative to the collar 95 using power from the motor 21. More specifically, the drive mechanism 3 is configured to move the pin gripping portion 165 that grips the pin 91 along the drive axis A1 relative to the tool body 10 and the anvil 161.

[0043] The drive mechanism 3 of this embodiment includes a planetary reducer 31 , a drive gear 32 , and a ball screw mechanism 4 .

[0044] The planetary reducer 31 is disposed coaxially with the motor 21 in front of the motor 21 within the lower half of the tool body 10. The drive gear 32 is disposed coaxially with the planetary reducer 31 in front of the planetary reducer 31. The planetary reducer 31 is configured to increase the torque input from the motor shaft 211 and rotate the drive gear 32.

[0045] The ball screw mechanism 4 is a motion conversion mechanism configured to convert rotational motion into linear motion. As shown in FIGS. 3 and 4, the ball screw mechanism 4 is mainly composed of a nut 41 and a screw shaft 45. In this embodiment, the ball screw mechanism 4 is configured to convert the rotational motion of the nut 41 into linear motion of the screw shaft 45, thereby moving the pin gripping portion 165 linearly. The ball screw mechanism 4 is housed in the upper half of the tool body 10.

[0046] The nut 41 is supported relative to the tool body 10 so as to be substantially immovable in the front-to-rear direction and rotatable about the drive shaft A1. In this embodiment, the nut 41 is accommodated in the inner housing 105. The nut 41 is formed in a cylindrical shape and has a driven gear 411 integrally provided on the outer periphery. The nut 41 is supported on the front and rear sides of the driven gear 411 by two radial bearings 412, 413 supported by the tool body 10. The driven gear 411 meshes with the drive gear 32.

[0047] The screw shaft 45 is engaged with the nut 41 in a state where it is substantially unable to rotate around the drive axis A1 relative to the tool body 10 but is movable in the front-rear direction along the drive axis A1. More specifically, the screw shaft 45 is configured as an elongated body and is inserted into the nut 41 so as to extend along the drive axis A1. Although not shown in detail, a spiral track is defined by grooves formed on the inner peripheral surface of the nut 41 and the outer peripheral surface of the screw shaft 45. A number of balls are rollably arranged within the track. The screw shaft 45 is engaged with the nut 41 via these balls.

[0048] The rear end of the threaded shaft 45 protrudes rearward from the inner housing 105 through an opening 106 that penetrates the rear wall of the inner housing 105 in the front-rear direction. An extension shaft 451 is coaxially connected and fixed to the rear end of the threaded shaft 45 and is integrated with the threaded shaft 45. Hereinafter, the integrated threaded shaft 45 and extension shaft 451 will be collectively referred to as the drive shaft 450.

[0049] The drive shaft 450 has a through hole that penetrates the drive shaft 450 along the drive axis A1. A collection container 19 is removably attached to the rear end of the tool body 10 (see FIG. 1). The pintail separated from the fastener 9 passes through the through hole of the drive shaft 450 to reach the collection container 19 and is stored in the collection container 19.

[0050] As shown in FIGS. 3 to 5, a rotation-preventing member 46 is connected to the drive shaft 450 and is integrally formed with the drive shaft 450 so as to be immovable relative to the drive shaft 450. The rotation-preventing member 46 is disposed around the rear end of the threaded shaft 45 and includes a base portion 461 fixed to the threaded shaft 45 and two arm portions 465 extending left and right from the base portion 461. A bearing 466 is attached to the tip of each arm portion 465. Meanwhile, a pair of left and right guide plates 121 are fixed inside the tool body 10. Each guide plate 121 has a guide groove 123 extending in the front-rear direction. The left and right bearings 466 are disposed in the left and right guide grooves 123, respectively.

[0051] The anti-rotation member 46 engages with the guide plate 121 via the bearing 466, thereby preventing the drive shaft 450 from rotating around the drive axis A1 due to the torque generated when the nut 41 rotates. Therefore, as the nut 41 rotates around the drive axis A1 in response to the driving of the motor 21, the drive shaft 450 moves linearly in the front-to-rear direction relative to the nut 41 and the tool body 10.

[0052] A magnet holder 47 that holds a magnet 48 is fixed to the upper end of the anti-rotation member 46. In other words, the magnet holder 47 and the magnet 48 are integrated with the drive shaft 450 via the anti-rotation member 46. The magnet holder 47 holds the magnet 48 so that the magnet 48 is exposed upward. As the drive shaft 450 moves in the front-to-rear direction along the drive axis A1, the magnet 48 moves in the front-to-rear direction along a movement axis parallel to the drive axis A1.

[0053] The position detection mechanism 8 is a mechanism that detects the position of the drive shaft 450, and therefore the pin gripping portion 165, by detecting the magnetic field generated by the magnet 48. As shown in Fig. 3, in this embodiment, the position detection mechanism 8 includes two magnetic sensors 80 (a first sensor 81 and a second sensor 82) that are spaced apart in the front-rear direction near the movement axis of the magnet 48.

[0054] Each magnetic sensor 80 is a sensor (Hall sensor, Hall effect sensor) configured to detect the presence or absence of a magnetic field and the strength of the magnetic field using the Hall effect. Each magnetic sensor 80 is connected to the controller 20 (see FIG. 1) via an electric wire (not shown), and is configured to output a predetermined detection signal to the controller 20 when the magnet 48 is located within the detection range of the magnetic sensor 80. The detection result by the magnetic sensor 80 is used to control the drive of the motor 21, and ultimately to control the movement of the pin gripping portion 165. Control based on the detection result of the magnetic sensor 80 will be described in detail later.

[0055] As shown in Figures 3 and 4, the front and rear sides of the nut 41 are provided with a front receiving portion 42 and a rear receiving portion 43, respectively, which are configured to receive the axial load (thrust load) acting on the nut 41.

[0056] The front receiving portion 42 includes a thrust bearing 421 disposed between the front end of the nut 41 and the front end of the tool body 10 (specifically, the inner housing 105) in the front-rear direction. The thrust bearing 421 is provided to receive a reaction force acting on the nut 41 in the forward direction when the drive shaft 450 and the pin gripping portion 165 are moved rearward relative to the tool body 10, while allowing the nut 41 to rotate.

[0057] The thrust bearing 421 is fitted around and supported by a cylindrical sleeve 425. The sleeve 425 has a flange 426 at its front end that protrudes radially outward. The sleeve 425 is fixedly held in the tool body 10 with the flange 426 fitted into the inner housing 105.

[0058] The rear receiving portion 43 is disposed between the rear end of the nut 41 and the rear end of the tool body 10 (specifically, the inner housing 105) in the front-rear direction. The rear receiving portion 43 includes a thrust bearing 431, an intervening member 433, and an elastic member 437.

[0059] The thrust bearing 431 is disposed on the rear side of the rear end of the nut 41. The thrust bearing 431 is provided to allow the nut 41 to rotate while receiving a rearward reaction force acting on the nut 41 when the drive shaft 450 and the pin gripping portion 165 are moved forward relative to the tool body 10.

[0060] The intervening member 433 is interposed between the thrust bearing 431 and the rear end of the tool body 10 (specifically, the inner housing 105) in the front-rear direction. In this embodiment, the intervening member 433 is formed as a cylindrical member having a flange portion 434 in the center. The intervening member 433 is disposed inside the inner housing 105 with the screw shaft 45 coaxially inserted therethrough. The thrust bearing 431 is fitted around the cylindrical front end of the intervening member 433.

[0061] The elastic member 437 is interposed between the flange portion 434 of the intervening member 433 and the rear end portion of the tool body 10 (more specifically, the inner housing 105) in the front-rear direction. In this embodiment, a rubber O-ring is used as the elastic member 437. When a force acts to move the nut 41 rearward relative to the tool body 10, the elastic member 437 elastically deforms, thereby allowing the nut 41 and the intervening member 433 to move slightly rearward relative to the tool body 10.

[0062] More specifically, the elastic member 437 is arranged between the flange portion 434 and the rear end portion of the inner housing 105 in a pressurized state (slightly compressed state). As a result, the intervening member 433, the thrust bearing 431, and the nut 41 are urged forward with respect to the tool body 10 by the elastic member 437. When the drive shaft 450 is stationary, the intervening member 433 is held in a position where the front surface of the flange portion 434 abuts against the thrust bearing 431 and the rear surface of the flange portion 434 is spaced slightly forward from the front surface of the rear wall portion of the inner housing 105. In addition, the front end of the nut 41 is held in a position where it abuts against the rear surface of the rear raceway of the thrust bearing 421 of the front receiving portion 42.

[0063] Furthermore, the cylindrical rear end of intervening member 433 is slidably disposed within opening 106 in the rear wall of inner housing 105. When drive shaft 450 is stopped (when substantially no rearward force is acting on nut 41), the rear end of intervening member 433 is disposed in the front-to-rear direction at approximately the same position as or slightly forward of the rear end of opening 106 of inner housing 105. The position of intervening member 433 at this time is referred to as the forwardmost position of intervening member 433.

[0064] On the other hand, when the drive shaft 450 is moved forward relative to the tool body 10 and a rearward reaction force acts on the nut 41, the nut 41, thrust bearing 431, and intervening member 433 move slightly rearward relative to the tool body 10 while compressing the elastic member 437, as shown in Fig. 6. As a result, the rear end of the intervening member 433 protrudes slightly rearward from the rear end of the opening 106 of the inner housing 105. The position of the intervening member 433 at this time is referred to as the protruding position of the intervening member 433.

[0065] When the drive shaft 450 moves forward, the rear end of the intervening member 433 in the protruding position abuts against the front surface of the base portion 461 of the anti-rotation member 46, thereby preventing the drive shaft 450 from moving forward any further. In other words, the anti-rotation member 46 and the intervening member 433 cooperate to function as a positioning portion or stopper that positions the drive shaft 450, and therefore the pin gripping portion 165, at the forward-most position relative to the tool body 10.

[0066] In this embodiment, the inner housing 105 is made of aluminum to reduce weight, whereas the anti-rotation member 46 and the intervening member 433 that come into contact with each other are made of iron to ensure strength.

[0067] The nose portion 16 will now be described.

[0068] 2, the nose portion 16 is mainly composed of an anvil 161 and a pin holding portion 165. The structures of the anvil 161 and the pin holding portion 165 are publicly known, so they will be briefly described below.

[0069] The anvil 161 is a generally cylindrical body and has a bore 162 extending along the drive axis A1. The tip of the bore 162 is engageable with the collar 95 of the fastener 9 (see FIG. 1). The anvil 161 is detachably connected to the front end of the tool body 10 (inner housing 105) via a connecting member.

[0070] The pin gripping portion 165 is configured to be able to grip the pin 91 (shank) of the fastener 9, and is held so as to be movable in the front-to-rear direction along the drive axis A1 relative to the anvil 161. More specifically, the pin gripping portion 165 is held in the bore 162 coaxially with the anvil 161, and is slidable within the bore 162. The pin gripping portion 165 has a plurality of claws that can grip the shank of the pin 91. The pin gripping portion 165 is configured so that the gripping force of the claws increases as the pin gripping portion 165 moves rearward relative to the anvil 161.

[0071] The rear end of the pin gripping portion 165 is connected to the front end of the screw shaft 45 via a connecting member 166. Therefore, the pin gripping portion 165 moves in the front-rear direction together with the screw shaft 45 (drive shaft 450). The pin gripping portion 165 and the connecting member 166 extend along the drive axis A1 and define a passage that communicates with the through-hole of the drive shaft 450. The pintail passes through the pin gripping portion 165, the connecting member 166, and the drive shaft 450, and is stored in the collection container 19.

[0072] Furthermore, the rear end of the connecting member 166 has a larger diameter than the threaded shaft 45 and is slidable within the bore 162 of the anvil 161. A flange portion 426 of a sleeve 425 fixed to the tool body 10 abuts against the rear end of the connecting member 166, thereby preventing the drive shaft 450 from moving further rearward. In other words, the sleeve 425 and the connecting member 166 cooperate to function as a positioning portion or stopper that positions the drive shaft 450, and therefore the pin gripping portion 165, at the rearmost position relative to the tool body 10. The connecting member 166 and the sleeve 425, which abut against each other, are also made of iron to ensure strength.

[0073] The handle 17 and the elements disposed therein will now be described.

[0074] 1, the portion of handle 17 other than the lower end is configured as a grip portion 170, and has a thickness suitable for gripping. On the other hand, the lower end of handle 17 is formed in a rectangular box shape and houses controller 20. Hereinafter, the lower end of handle 17 will also be referred to as controller housing portion 175.

[0075] A trigger 171 is provided on the front side of the upper end of the handle 17 (grip 170). A switch 172 is housed within the upper end of the grip 170. The switch 172 is normally kept off and is configured to be turned on while the trigger 171 is pressed.

[0076] The controller 20 is a control device configured to control the operation of the fastening tool 1 (for example, driving the motor 21), and includes at least one processor / processing circuit and at least one memory mounted on a circuit board. Note that the controller 20 in this embodiment is configured as a microcomputer including a CPU, ROM, RAM, etc. The controller 20 is electrically connected to the magnetic sensor 80 (see FIG. 2), switch 172, etc. via electric wires (not shown).

[0077] The following describes the movement of the pin gripping portion 165 and the position detection of the pin gripping portion 165 by the magnetic sensor 80 (first sensor 81 and second sensor 82) of the position detection mechanism 8. As described above, the drive shaft 450 and the pin gripping portion 165 move integrally, and therefore the movement of the pin gripping portion 165 is synonymous with the movement of the drive shaft 450.

[0078] As described above, the pin gripping portion 165 is movable between the frontmost position and the rearmost position within its movable range in the front-rear direction. However, the pin gripping portion 165 is usually moved between the frontmost position and a rear stop position that is forward of the rearmost position.

[0079] 6, when the pin gripping portion 165 moves forward (returns), it moves forward until the front surface of the base portion 461 of the anti-rotation member 46 abuts against the rear end of the intervening member 433, which is positioned in the protruding position, and is positioned at the forward-most position. Thereafter, when the motor 21 is stopped and the movement of the pin gripping portion 165 is stopped, the intervening member 433 returns to the forward-most position due to the biasing force of the elastic member 437, as shown in FIG. 4. Therefore, when the pin gripping portion 165 is in the forward-most position and the motor 21 is stopped (hereinafter, this state will be referred to as the initial state of the fastening tool 1), the front surface of the base portion 461 of the anti-rotation member 46 is positioned slightly rearward from the rear end of the intervening member 433 and the rear wall portion of the inner housing 105.

[0080] The first sensor 81 of the position detection mechanism 8 is provided to detect the pin gripping portion 165 when the pin gripping portion 165 is at a predetermined position (hereinafter referred to as the first detection position) rearward of the forward-most position. More specifically, the first sensor 81 is disposed at a position where it can detect the magnet 48 as the pin gripping portion 165 reaches the first detection position during its forward movement. In this embodiment, as shown in FIG. 7 , when the pin gripping portion 165 is at the first detection position, the magnet 48 is located substantially directly below the first sensor 81. Furthermore, as shown in FIG. 8 , when the pin gripping portion 165 is at the first detection position, the anti-rotation member 46 is located at a position spaced rearward from the rear end of the intervening member 433 and the rear wall portion of the inner housing 105.

[0081] When the first sensor 81 detects the magnet 48, it outputs a detection signal to the controller 20. In this embodiment, when the controller 20 receives a detection signal from the first sensor 81 during the return movement of the pin gripping portion 165, it reduces the rotational speed of the motor 21 to a predetermined speed before the pin gripping portion 165 reaches the forward-most position, and then maintains the reduced speed. Hereinafter, the position at which the rotational speed of the motor 21 reaches the predetermined speed will be referred to as the deceleration completion position of the pin gripping portion 165. As shown in FIGS. 9 and 10 , when the pin gripping portion 165 is in the deceleration completion position, the anti-rotation member 46 is positioned further forward than when the pin gripping portion 165 is in the first detection position, but is still separated from the rear end of the intervening member 433 and the rear wall portion of the inner housing 105.

[0082] On the other hand, in this embodiment, when the pin gripping portion 165 moves rearward (pulls), it is stopped at a rear stop position forward of the rearmost position.

[0083] The second sensor 82 is provided to detect the pin gripping portion 165 when the pin gripping portion 165 is at a predetermined position (hereinafter referred to as the second detection position) forward of the rearmost position and the rear stop position. More specifically, the second sensor 82 is disposed rearward of the first sensor 81 at a position where the second sensor 82 can detect the magnet 48 as the pin gripping portion 165 reaches the second detection position while moving rearward. Although not shown, in this embodiment, when the pin gripping portion 165 is at the second detection position, the magnet 48 is located substantially directly below the second sensor 82. Furthermore, the second detection position of the pin gripping portion 165 is set rearward of the position of the pin gripping portion 165 when the pintail of the pin 91 is torn off after being strongly pulled rearward by the pin gripping portion 165.

[0084] In this embodiment, the first sensor 81 and the second sensor 82 are mounted on a common circuit board and are arranged above and facing the movement axis of the magnet 48. However, the first sensor 81 and the second sensor 82 may also be mounted on separate circuit boards.

[0085] When the second sensor 82 detects the magnet 48, it outputs a detection signal to the controller 20. As will be described in detail later, in this embodiment, when the controller 20 recognizes a detection signal from the second sensor 82 during the pulling operation of the pin gripping portion 165, it quickly stops the motor 21. While the motor 21 decelerates and comes to a complete stop, the pin gripping portion 165 moves slightly rearward and stops at the rear stop position.

[0086] It is possible that, due to some malfunction, second sensor 82 may not be able to detect that pin gripping portion 165 has reached the second detection position during the pulling operation. If such a situation occurs, sleeve 425 and connecting member 166 come into contact with each other, thereby preventing pin gripping portion 165 from moving rearward beyond the rearmost position.

[0087] The electrical configuration of the fastening tool 1 will be described below.

[0088] 11, a three-phase inverter 201 and a Hall sensor 203 are electrically connected to the controller 20 of the fastening tool 1. The three-phase inverter 201 includes a three-phase bridge circuit using six semiconductor switching elements, and causes each switching element of the three-phase bridge circuit to perform a switching operation in accordance with a duty ratio indicated by a control signal from the controller 20. The Hall sensor 203 includes three Hall elements arranged corresponding to each phase of the motor 21, and is configured to output a signal indicating the rotation angle (rotation position) of the rotor (motor shaft 211) of the motor 21 to the controller 20.

[0089] In addition, a current detection amplifier 205 is electrically connected to the controller 20. The current detection amplifier 205 converts the drive current of the motor 21 into a voltage using a shunt resistor, and outputs the amplified signal to the controller 20.

[0090] Furthermore, the switch 172 of the trigger 171, the first sensor 81, and the second sensor 82 are electrically connected to the controller 20. In this embodiment, the controller 20 is configured to control the rotation speed of the motor 21 by PWM control. The controller 20 controls the operation of the drive mechanism 3 and, ultimately, the movement of the pin gripping portion 165 by appropriately controlling the drive of the motor 21 based on signals output from the switch 172, the first sensor 81, the second sensor 82, and the current detection amplifier 205.

[0091] The control process of the motor 21 in the fastening tool 1 will be described below.

[0092] First, the control process (hereinafter referred to as the first control process) of the motor 21 during the pulling operation of the pin gripping portion 165 will be described with reference to Figures 12 and 13. The first control process is started when the user presses the trigger 171 and turns on the switch 172. The controller 20 (more specifically, the CPU) executes the first control process by reading and executing a program stored in memory (for example, a ROM). In the following description and in the flowcharts referenced, "step" is abbreviated as "S."

[0093] At the start of the first control process (time t0 in FIG. 13), the pin gripping portion 165 is in the forward-most position (see FIGS. 3 and 4). As shown in FIG. 12, when the first control process is started, the controller 20 sets a duty ratio for PWM control to drive the motor 21 at a predetermined rotational speed. In this embodiment, the rotational speed during the pulling operation is set to the maximum speed of the motor 21 in consideration of the efficiency of the fastening operation, and the duty ratio is set to 100% (S110). However, in another embodiment, the rotational speed during the pulling operation and the corresponding duty ratio may be changed as appropriate.

[0094] The controller 20 drives the motor 21 at the set duty ratio (S120). The rotation direction of the motor shaft 211 during the pulling operation is the positive direction. The drive mechanism 3 is driven, and the pin gripping portion 165 gripping the pin 91 of the fastener 9 is moved backward. The rotation speed of the motor 21 increases to the maximum speed (from time t0 to t1) and is maintained at the maximum speed (from time t1 to t2).

[0095] The controller 20 monitors the detection signal output from the second sensor 82 while the motor 21 is being driven (i.e., while the pin gripping portion 165 is moving rearward) (S130). While the controller 20 does not recognize a detection signal from the second sensor 82 (i.e., while the pin gripping portion 165 has not reached the second detection position), the controller 20 continues to drive the motor 21 at the maximum speed (S130: NO, S110, S120). During this time, the pin gripping portion 165 is moved rearward while pulling the pin 91, and the work material W is fastened by the fastener 9. As described above, the pintail is torn off before the pin gripping portion 165 reaches the second detection position.

[0096] When the pin gripping portion 165 reaches the second detection position and a detection signal is output from the second sensor 82, the controller 20 stops the motor 21 (rotation of the motor shaft 211) (S140) and ends the first control process. In S140, the motor 21 may be stopped, for example, by simply cutting off power to the motor 21. Alternatively, the motor 21 may be braked to quickly stop the motor 21. In this embodiment, the controller 20 stops the motor 21 in the shortest time possible by short-circuiting all three-phase terminals to generate maximum braking force (the period from time t2 to t3). When the rotation of the motor 21 completely stops (time t3) and the pin gripping portion 165 stops at the rear stop position, the pulling action of the pin gripping portion 165 ends.

[0097] Although not explicitly shown as a step in the flowchart, in this embodiment, when the trigger 171 is released and the switch 172 is turned off during the first control process, the controller 20 shifts the process to S140, stops the motor 21, ends the first control process, and shifts to the second control process described below.

[0098] Next, the control process of the motor 21 during the return motion of the pin gripping portion 165 (hereinafter referred to as the second control process) will be described with reference to Figures 13 and 14. The second control process is started when the user releases the pressure on the trigger 171 after the above-mentioned first control process has ended and switches the switch 172 from on to off. As with the first control process, the controller 20 (more specifically, the CPU) executes the second control process by reading and executing a program stored in a memory (for example, a ROM).

[0099] As described above, at the start of the second control process (time t4 in FIG. 13), the pin gripping portion 165 is in the rear stop position. As shown in FIG. 14, when the second control process is started, the controller 20 sets a duty ratio for PWM control to drive the motor 21 at a predetermined first rotation speed. In this embodiment, the first rotation speed during the return movement is set to the maximum speed of the motor 21 in consideration of the efficiency of the fastening operation, and the duty ratio is set to 100% (S210). However, in another embodiment, the first rotation speed and the corresponding duty ratio may be changed as appropriate.

[0100] The controller 20 drives the motor 21 at the set duty ratio (S220). The rotation direction of the motor shaft 211 during the return movement is reversed. The drive mechanism 3 is driven, and the pin gripping portion 165 is moved forward. The rotation speed of the motor 21 increases to a first rotation speed (maximum speed) (a period from time t4 to t5) and is maintained at the maximum speed (a period from time t5 to t6).

[0101] While the motor 21 is being driven (i.e., while the pin gripping portion 165 is moving forward), the controller 20 monitors the signal output from the first sensor 81 (S230). While the controller 20 does not recognize a detection signal from the first sensor 81 (i.e., while the pin gripping portion 165 has not reached the first detection position), the controller 20 continues to drive the motor 21 at the maximum speed (S230: NO, S210, S220).

[0102] When the pin gripping portion 165 reaches the first detection position (see FIGS. 7 and 8) and a detection signal is output from the first sensor 81 (S230: YES), the controller 20 decelerates the motor 21 to a predetermined second rotation speed (i.e., reduces the rotation speed of the motor 21) (S240). The second rotation speed is slower than the first rotation speed.

[0103] In this embodiment, as described above, the abutment between the intervening member 433 and the anti-rotation member 46 completely stops the forward movement of the pin gripping portion 165 at the forwardmost position. Therefore, in order to reduce the impact caused by the collision between the intervening member 433 and the anti-rotation member 46, it is preferable that the second rotation speed be less than 20% of the first rotation speed. In this embodiment, the second rotation speed is set to 10% of the first rotation speed, that is, the maximum rotation speed of the motor 21. This makes it possible to effectively reduce the impact caused by the collision between the intervening member 433 and the anti-rotation member 46 while setting the first rotation speed to the maximum speed in consideration of work efficiency.

[0104] Furthermore, in this embodiment, the second rotation speed is set so that the stress caused by the contact between intervening member 433 and anti-rotation member 46 does not exceed the fatigue limits of intervening member 433 and anti-rotation member 46. This effectively reduces the possibility of damage to intervening member 433 and anti-rotation member 46.

[0105] The deceleration in S240 can be performed, for example, by generating a braking force by short-circuiting the terminals of at least two of the three phases of the motor 21 (using a so-called short-circuit brake). The magnitude of the braking force can be adjusted by changing the number of phases to be short-circuited and / or the short-circuit duration. In this embodiment, the position of the first sensor 81 (the distance between the first detection position and the deceleration completion position) and the braking force applied to the motor 21 are set so that the rotational speed of the motor 21 is reliably reduced to the second rotational speed when the pin gripping portion 165 reaches the deceleration completion position (see FIGS. 9 and 10). The deceleration completion position of the pin gripping portion 165 is set a predetermined distance behind the forward-most position (see FIG. 6).

[0106] In this embodiment, in S240, the controller 20 generates maximum braking force by short-circuiting all three-phase terminals, and decelerates the motor 21 to the second rotation speed in the shortest time (shortest distance) (the section from time t6 to t7). This maximizes the section in which the motor 21 is driven at the first rotation speed (maximum speed) during the return movement, thereby optimizing work efficiency.

[0107] In another embodiment, the deceleration in S240 may be performed by, for example, reducing the duty ratio for PWM control. The controller 20 may change the duty ratio so that the rotation speed of the motor 21 decreases at a constant rate of change (linearly). Alternatively, the controller 20 may change the duty ratio so that the rotation speed decreases quadratically or exponentially (nonlinearly).

[0108] The controller 20 waits until the actual rotation speed of the motor 21, which is determined based on the signal from the Hall sensor 203, drops to the second rotation speed (S250). When the actual rotation speed of the motor 21 reaches the second rotation speed (time t7), the controller 20 sets the duty ratio to 10% (S260) and continues driving the motor 21 at the second rotation speed (S270) (interval from time t7 to t8).

[0109] The controller 20 determines whether or not the intervening member 433 and the anti-rotation member 46 have come into contact with each other (i.e., whether or not the pin gripping portion 165 has reached the forward-most position) (S280). The contact between the intervening member 433 and the anti-rotation member 46 can be detected, for example, by detecting a physical quantity related to the driving state of the motor 21. Specifically, when the forward movement of the pin gripping portion 165 is prevented in response to the contact between the intervening member 433 and the anti-rotation member 46, the drive current value of the motor 21 increases sharply and the rotation speed of the motor 21 decreases sharply. Therefore, the drive current value of the motor 21 or the rotation speed of the motor 21 is a physical quantity suitable for determining whether or not the intervening member 433 and the anti-rotation member 46 have come into contact with each other.

[0110] In this embodiment, the rate of change in the drive current value of the motor 21 is used to detect contact between the interposition member 433 and the anti-rotation member 46. More specifically, the controller 20 determines whether the rate of increase in the drive current value of the motor 21 has exceeded a predetermined rate of increase based on the signal output from the current detection amplifier 205. The controller 20 continues to drive the motor 21 at the second rotation speed while the rate of increase in the drive current value of the motor 21 does not exceed the predetermined rate of increase (S280: NO, S260, S270).

[0111] In another embodiment, it may be determined whether the drive current value exceeds a predetermined threshold value, or whether the rotation speed of the motor 21 falls below a predetermined threshold value, or whether the rate of decrease in the rotation speed of the motor 21 falls below a predetermined rate of decrease.

[0112] When the controller 20 determines that the intervening member 433 and the anti-rotation member 46 have come into contact and that the rate of increase in the drive current value of the motor 21 has exceeded a predetermined rate of increase (S280: YES) (time t8 in FIG. 13), the controller 20 stops the motor 21 (S290) and ends the second control process. As in S140 of the first control process, the motor 21 may be stopped simply by cutting off power to the motor 21, or the motor 21 may be braked. With the pin gripping portion 165 positioned at the foremost position, the intervening member 433 returns from the protruding position to the foremost position, and the return movement of the pin gripping portion 165 ends.

[0113] As described above, in this embodiment, when the pin gripping portion moves forward and returns to the forward-most position, the intervening member 433 and the anti-rotation member 46 come into contact, the pin gripping portion 165 is positioned at the forward-most position, and the controller 20 stops the motor 21. In other words, the motor 21 is stopped in a state where the pin gripping portion 165 is physically prevented from moving forward at the forward-most position. This allows the pin gripping portion 165 to be reliably returned to the predetermined forward-most position.

[0114] Furthermore, when the first sensor 81 detects that the pin gripping portion 165 has reached a first detection position, which is rearward of the foremost position, during the forward movement of the pin gripping portion 165, the controller 20 decelerates the motor 21 and, therefore, the pin gripping portion 165. Because the deceleration of the motor 21 and the pin gripping portion 165 is completed before the pin gripping portion 165 reaches the foremost position, the anti-rotation member 46 collides with the intervening member 433 while moving at the second rotational speed after deceleration. Therefore, the impact when the intervening member 433 and the anti-rotation member 46 collide with each other can be effectively reduced.

[0115] Second Embodiment A second embodiment of the present disclosure will be described with reference to Fig. 15. In the second embodiment, a part of the first control process of the motor 21 executed by the controller 20 is different from that in the first embodiment, but the other process contents and the configuration of the fastening tool 1 are substantially the same as those in the first embodiment. Therefore, in the following, the same step numbers are assigned to processes that are substantially the same as those in the first embodiment, and their description is omitted or simplified, and only the process contents that are different from those in the first embodiment will be described.

[0116] In the first control process of this embodiment, the same process as the second control process of the first embodiment is performed. Briefly, when the controller 20 detects that the pin gripping portion 165 has reached the second detection position, the controller 20 decelerates the motor 21 from the first rotation speed to the second rotation speed. Thereafter, when the pin gripping portion 165 reaches the rearmost position and contact between the sleeve 425 and the connecting member 166 (see FIG. 2) is detected, the controller 20 stops the motor 21.

[0117] 15, when the first control process is started, the controller 20 sets a duty ratio (100%) corresponding to a predetermined first rotation speed (maximum speed) during a pulling operation (S110). The controller 20 drives the motor 21 at the set duty ratio (S120). The controller 20 continues to drive the motor 21 at the maximum speed while it does not recognize a detection signal from the second sensor 82 (i.e., while the pin gripping portion 165 has not reached the second detection position) (S130: NO, S110, S120).

[0118] When the pin gripping portion 165 reaches the second detection position and a detection signal is output from the second sensor 82, the controller 20 decelerates the motor 21 (i.e., reduces the rotational speed of the motor 21) (S131). In this embodiment, the movement of the pin gripping portion 165 is completely stopped by the abutment of the sleeve 425 with the connecting member 166. Therefore, similar to the second rotational speed in the first embodiment, the second rotational speed in this embodiment is preferably less than 20% of the first rotational speed (maximum speed) at the start of the pulling operation in order to reduce the impact caused by the abutment of the sleeve 425 with the connecting member 166. In this embodiment, the rotational speed after deceleration is set to 10% of the maximum speed of the motor 21.

[0119] The deceleration method in S131 may be the same as the deceleration method in S240 of the second control process in the first embodiment. For example, the controller 20 generates maximum braking force by short-circuiting all three-phase terminals of the motor 21 so that the second rotation speed is obtained at a deceleration completion position between the second detection position and the rearmost position, and decelerates the motor 21 in the shortest time (shortest distance). However, in another embodiment, the deceleration method during the backward movement of the pin gripping portion 165 may be different from the deceleration method during the forward movement of the pin gripping portion 165.

[0120] The controller 20 waits until the actual rotation speed of the motor 21 decreases to the second rotation speed (S132). When the actual rotation speed of the motor 21 reaches the second rotation speed, the controller 20 sets the duty ratio to 10% (S133) and continues driving the motor 21 at the second rotation speed (S134).

[0121] The controller 20 determines whether the sleeve 425 and the connecting member 166 have come into contact with each other (i.e., whether the pin gripping portion 165 has reached the rearmost position). The contact between the sleeve 425 and the connecting member 166 can be detected in the same manner as the contact between the intervening member 433 and the anti-rotation member 46. That is, the controller 20 determines whether the sleeve 425 and the connecting member 166 have come into contact with each other based on whether the rate of increase in the drive current value of the motor 21 has exceeded a predetermined rate of increase (S135). The controller 20 continues to drive the motor 21 at the second rotation speed while the rate of increase in the drive current value of the motor 21 does not exceed the predetermined rate of increase (S135: NO, S133, S134).

[0122] When the controller 20 determines that the sleeve 425 and the connecting member 166 have come into contact and that the rate of increase in the drive current value of the motor 21 has exceeded a predetermined rate of increase (S135: YES), it stops the motor 21 (S136) and ends the first control process. As in S290 of the second control process, the motor 21 may be stopped simply by cutting off power to the motor 21, or the motor 21 may be braked. With the pin gripping portion 165 positioned at the rearmost position, the pulling operation of the pin gripping portion 165 ends.

[0123] As described above, in this embodiment, the fastening tool 1 operates when the pin gripping portion 165 moves rearward in the same manner as when the pin gripping portion 165 moves forward. In other words, the fastening operation is performed while the pin gripping portion 165 moves rearward, and when it reaches the rearmost position, the sleeve 425 and the connecting member 166 come into contact, the pin gripping portion 165 is positioned at the rearmost position, and the controller 20 stops the motor 21. This allows the pin gripping portion 165 to be reliably positioned at the rearmost position.

[0124] Furthermore, when the second sensor 82 detects that the pin gripping portion 165 has reached a second detection position, which is forward of the rearmost position, during the process of the pin gripping portion 165 moving rearward, the controller 20 decelerates the motor 21 and, therefore, the pin gripping portion 165. Because the deceleration of the motor 21 and the pin gripping portion 165 is completed before the motor 21 and the pin gripping portion 165 reach the rearmost position, the connecting member 166 collides with the sleeve 425 while moving at the second rotational speed after deceleration. Therefore, the impact when the sleeve 425 and the connecting member 166 collide with each other can be effectively reduced.

[0125] The correspondence between each component (feature) of the above embodiment and each component (feature) of the present disclosure or invention is shown below. However, each component of the embodiment is merely an example and does not limit each component of the present disclosure or invention.

[0126] The first sensor 81 is an example of a "first detection device." The base portion 461 of the anti-rotation member 46 is an example of a "first abutment portion." The rear end portion of the intervening member 433 is an example of a "second abutment portion." The current detection amplifier 205 is an example of a "second detection device." The controller 20 (more specifically, the CPU) is an example of a "control device." The ball screw mechanism 4 is an example of a "screw feed mechanism." The nut 41, the screw shaft 45, and the anti-rotation member 46 are examples of a "nut member," a "shaft member," and a "anti-rotation portion," respectively. The rear receiving portion 43 is an example of a "reaction force receiving portion." The second sensor 82 is an example of a "third detection device." The rear end portion of the connecting member 166 is an example of a "third abutment portion." The flange portion of the sleeve 425 is an example of a "fourth abutment portion."

[0127] The fastening tool according to the present disclosure is not limited to the fastening tool 1 of the above embodiment. For example, the following non-limiting examples are possible. Furthermore, at least one of these modifications may be adopted in combination with the fastening tool 1 of the embodiment and at least one of the features described in the claims.

[0128] First, a modified example of the configuration for positioning the pin gripping portion 165 at the frontmost position and the rearmost position will be described.

[0129] The first and second abutment portions that come into contact with each other as the pin gripping portion 165 reaches the frontmost position from the rear are not limited to the anti-rotation member 46 and the intervening member 433. The first abutment portion may be a part of the pin gripping portion 165 or may be provided on a member connected to the pin gripping portion 165 (e.g., the extension shaft 451) as long as it is movable in the front-rear direction integrally with the pin gripping portion 165. The second abutment portion is sufficient as long as it is provided within the tool body 10 and can position the pin gripping portion 165 at the frontmost position by abutting against the first abutment portion. Therefore, the second abutment portion may be a part of the tool body 10 (e.g., the rear wall portion of the inner housing 105) or may be provided on a member connected to the tool body 10. Note that in the above embodiment, the intervening member 433 corresponding to the second abutment portion is allowed to move slightly in the front-rear direction relative to the tool body 10, but the second abutment portion may be immovable in the front-rear direction relative to the tool body 10.

[0130] The third and fourth contact portions that position the pin gripping portion 165 at the rearmost position are not limited to the connecting member 166 and the sleeve 425, and can be modified in the same manner as the first and second contact portions.

[0131] Below, modifications of the configuration of the position detection mechanism 8 (first sensor 81 and second sensor 82) and the control of the motor 21 according to the position of the pin gripping portion 165 will be described.

[0132] For example, the magnet 48 may be attached at any arbitrary position as long as it is movable in the front-to-rear direction integrally with the pin gripping portion 165. The positions of the first sensor 81 and the second sensor 82 may be changed as appropriate depending on the position of the magnet 48. Furthermore, instead of the magnetic sensor 80, the first sensor 81 and the second sensor 82 may be replaced by other types of sensors (for example, optical sensors such as photointerrupters) or mechanical switches.

[0133] Furthermore, the number of rotations of the motor 21 may be used to detect that the pin gripping portion 165 has reached the first detection position. More specifically, after the pin gripping portion 165 starts moving rearward from the forward-most position (i.e., after the driving of the motor 21 is started), the controller 20 counts the number of rotations of the motor 21 (hereinafter simply referred to as the number of rotations of the motor 21) based on a signal from the Hall sensor 203. When the pin gripping portion 165 moves forward, the controller 20 counts the number of rotations after the start of the forward movement and compares it with the number of rotations during the rearward movement of the pin gripping portion 165. The controller 20 can determine that the pin gripping portion 165 has reached the first detection position when the difference between the number of rotations after the start of the forward movement and the number of rotations during the rearward movement reaches a predetermined number. Furthermore, the controller 20 can determine that the pin gripping portion 165 has reached the second detection position when the number of rotations after the start of the rearward movement reaches the predetermined number.

[0134] In the above embodiment, in the second control process for moving the pin gripping portion 165 forward to the foremost position, the controller 20 completes deceleration when the pin gripping portion 165 reaches a deceleration-completed position rearward of the foremost position (before the intervening member 433 and the anti-rotation member 46 come into contact with each other). However, after the first sensor 81 detects that the pin gripping portion 165 has reached the first detection position, the controller 20 may control the motor 21 so that the rotation speed of the motor 21 becomes the second rotation speed when the pin gripping portion 165 reaches the foremost position. In other words, the controller 20 may continue to decelerate the motor 21 while the pin gripping portion 165 moves from the first detection position to the foremost position. The same applies to the control while the pin gripping portion 165 moves from the second detection position to the rearmost position in the second embodiment.

[0135] Other modifications will be described below.

[0136] The fastening tool 1 may be configured to fasten the work material W using a type of fastener different from the fastener 9 exemplified in the above embodiment (for example, a blind rivet or a axially retaining type fastener among multi-component fasteners). The fastening tool 1 may be compatible with multiple types of fasteners by replacing the anvil 161 and the pin gripping portion 165. The shapes, components, and connection manner of the tool body 10, nose portion 16 (anvil 161, pin gripping portion 165, etc.), and handle 17 may be changed as desired.

[0137] The motor 21 may be a motor other than a three-phase brushless DC motor (for example, a DC motor with brushes, or an AC motor). The fastening tool 1 may be configured to operate using power supplied from an external AC power source instead of the battery 145.

[0138] The drive mechanism 3 may be driven by the power of the motor 21 and may move the pin gripping portion 165 in the forward and backward directions relative to the anvil 161, and its components and arrangement may be changed as desired. For example, a screw feed mechanism including a nut and a screw shaft that are directly screwed together may be used instead of the ball screw mechanism 4. Power may be transmitted from the motor 21 to the ball screw mechanism 4 by a gear train different from that in the above embodiment.

[0139] Instead of a microcomputer, a programmable logic device such as an ASIC (Application Specific Integrated Circuits) or an FPGA (Field Programmable Gate Array) may be used for the controller 20 that controls the driving of the motor 21. The above-mentioned control processing may be distributed among multiple processors / processing circuits.

[0140] Furthermore, in consideration of the spirit of the present invention, the above-described embodiments, and their modifications, the following aspects are constructed. At least one of the following aspects can be adopted in combination with the above-described embodiments, their modifications, and at least one of the configurations (features) described in each claim. [Aspect 1] The control device is configured to reduce the rotational speed of the motor to a predetermined speed in response to the third detection device detecting that the pin gripping portion has reached the second detection position, and then drive the motor at the predetermined speed until the second detection device detects contact between the third abutment portion and the fourth abutment portion. [Aspect 2] The third detection device is a magnetic sensor. [Aspect 3] The rotational speed before deceleration is the maximum rotational speed of the motor, The rotation speed after deceleration is 15% or less of the rotation speed before deceleration. [Aspect 4] The reaction force receiving portion includes: (i) a receiving member disposed behind the nut member and supported by the tool body so as to be movable in the front-rear direction; and (ii) an elastic member disposed between the receiving member and the tool body in the front-rear direction and biasing the receiving member forward relative to the tool body. the receiving member is configured such that (i) it is normally disposed at a first position by the biasing force of the elastic member, and (ii) it receives the rearward reaction force acting on the nut member and moves rearward relative to the tool body to a second position, The second contact portion is a rear end portion of the receiving member, and contacts the first contact portion when the receiving member is in the second position. The interposing member 433 is an example of the "receiving member" in this embodiment, and the elastic member 437 is an example of the "elastic member." [Explanation of symbols]

[0141] 1: fastening tool, 10: tool body, 101: outer housing, 105: inner housing, 106: opening, 121: guide plate, 123: guide groove, 145: battery, 16: nose portion, 161: anvil, 162: bore, 165: pin gripping portion, 166: connecting member, 17: handle, 170: gripping portion, 171: trigger, 172: switch, 175: controller housing portion, 19: collection container, 20: controller, 201: three-phase inverter, 203: hall sensor, 205: current detection amplifier, 21: motor, 211: motor shaft, 3: drive mechanism, 31: planetary reducer, 32: drive gear, 4: ball screw mechanism, 41: nut, 4 11: driven gear, 412: radial bearing, 413: radial bearing, 42: front receiving portion, 421: thrust bearing, 425: sleeve, 426: flange portion, 43: rear receiving portion, 431: thrust bearing, 433: interposition member, 434: flange portion, 437: elastic member, 45: screw shaft, 450: drive shaft, 451: extension shaft, 46: anti-rotation member, 461: base portion, 465: arm portion, 466: bearing, 47: magnet holder, 48: magnet, 8: position detection mechanism, 80: magnetic sensor, 81: first sensor, 82: second sensor, 9: fastener, 91: pin, 95: collar, A1: drive shaft, W: working material

Claims

1. A fastening tool configured to fasten work materials using a fastener including a pin and a cylindrical portion, A tool body, a motor housed in the tool body; a pin gripping portion configured to grip the pin, the pin gripping portion being operably connected to the motor and movable relative to the tool body between a forward-most position and a rearward-most position by power of the motor along a drive axis that defines a front-to-rear direction of the fastening tool; a first detection device configured to detect that the pin gripping portion is at a first detection position between the front-most position and the rear-most position in the front-rear direction; a first abutment portion configured to move integrally with the pin gripping portion in the front-rear direction relative to the tool body; a second abutment portion provided in the tool body and configured to position the pin gripping portion at the forward-most position by abutting against the first abutment portion as the pin gripping portion moves from the rear to the forward-most position; a second detection device configured to detect contact between the first contact portion and the second contact portion; a control device configured to control the driving of the motor; The pin gripping portion is configured to fasten the work material with the fastener by moving rearward from the forwardmost position, the control device is configured to decelerate the motor in response to the first detection device detecting that the pin gripping portion has reached the first detection position while the pin gripping portion is moving forward, and then to stop the motor in response to the second detection device detecting contact between the first abutment portion and the second abutment portion.

2. The fastening tool according to claim 1, a control device configured to reduce the rotational speed of the motor to a predetermined speed in response to the first detection device detecting that the pin gripping portion has reached the first detection position, and then drive the motor at the predetermined speed until the second detection device detects contact between the first abutment portion and the second abutment portion.

3. The fastening tool according to claim 1 or 2, The fastening tool, wherein the second detection device is configured to detect a physical quantity related to a driving state of the motor.

4. The fastening tool according to claim 3, The fastening tool, characterized in that the second detection device is configured to detect at least one of the physical quantities: (i) a current value of the motor; (ii) a change in the current value; (iii) a rotational speed of the motor; and (iv) a change in the rotational speed.

5. The fastening tool according to any one of claims 1 to 4, The fastening tool, wherein the first detection device is a magnetic sensor.

6. The fastening tool according to any one of claims 1 to 5, The motor is a three-phase brushless motor, The fastening tool, wherein the control device is configured to generate a braking force by short-circuiting terminals of at least two phases, thereby decelerating the motor.

7. The fastening tool according to any one of claims 1 to 5, The fastening tool, wherein the control device is configured to decelerate the motor by changing a duty ratio for PWM control of the motor.

8. The fastening tool according to any one of claims 1 to 7, A fastening tool, characterized in that the rotational speed of the motor after deceleration is lower than 20% of the rotational speed before deceleration.

9. The fastening tool according to claim 8, a fastening tool characterized in that the rotational speed after deceleration is set so that the stress caused by the contact between the first contact portion and the second contact portion does not exceed the fatigue limit of the first contact portion and the second contact portion.

10. The fastening tool according to any one of claims 1 to 9, a screw feed mechanism operably connected to the motor and the pin gripper; The screw feed mechanism includes: (i) a nut member that is rotatably supported around the drive shaft within the tool body and is configured to be rotationally driven by the power of the motor; (ii) a shaft member that is operably engaged with the nut member so as to move linearly in the forward and backward directions integrally with the pin gripping portion in response to rotation of the nut member; the shaft member has a rotation prevention portion configured to inhibit rotation around the drive shaft by engaging with the tool body, A fastening tool, characterized in that a part of the anti-rotation portion is configured as the first abutment portion.

11. The fastening tool according to claim 10, a reaction force receiving portion disposed between the nut member and the first abutment portion in the front-rear direction and configured to receive a rearward reaction force acting on the nut member when the shaft member moves forward, A fastening tool, characterized in that a part of the reaction force receiving portion is configured as the second abutment portion.

12. The fastening tool according to any one of claims 1 to 11, a third detection device configured to detect that the pin gripping portion is at a second detection position between the first detection position and the rearmost position in the front-rear direction; and a third abutment portion configured to move integrally with the pin gripping portion in the front-rear direction relative to the tool body; a fourth abutment portion provided in the tool body and configured to position the pin gripping portion at the rearmost position by abutting against the third abutment portion as the pin gripping portion moves from the front to the rearmost position, the second detection device is further configured to detect contact between the third contact portion and the fourth contact portion, the control device is configured to decelerate the motor in response to the third detection device detecting that the pin gripping portion has reached the second detection position while the pin gripping portion is moving rearward, and thereafter to stop the rotation of the motor in response to the second detection device detecting contact between the third abutment portion and the fourth abutment portion.

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