Fastening tool

Abstract

The invention provides a fastening tool. The fastening tool includes: a tool body; a motor; a pin holding part capable of moving relative to the tool main body between a forefront position and a rearmost position; a first detection device that detects that the pin holding part is located at the first detection position; a first contact portion that moves in the front-rear direction with respect to the tool body integrally with the pin holding portion; a second contact part which is provided inside the tool main body and which positions the pin holding part at the forefront position by coming into contact with the first contact part; a second detection device that detects the contact between the first contact section and the second contact section; and a control device for controlling the driving of the motor. The control device decelerates the motor in response to the first detection device detecting that the pin gripping part reaches the first detection position during the forward movement of the pin gripping part, and then stops the motor in response to the second detection device detecting the contact between the first contact part and the second contact part. Therefore, the positioning accuracy of the pin holding part can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a fastening tool configured in a manner that fastens a work material using a fastener. BACKGROUND

[0002] The known fastening tool is configured to deform the fastener by moving a pin holding portion that holds a pin of the fastener rearward from a prescribed position to fasten the work material, and then move the pin holding portion forward to return to the prescribed position. The position of the pin holding portion in the initial state (referred to as an initial position, home position, etc.) is preferably set in a manner that the pin holding portion can hold the pin with an appropriate force. Therefore, for example, the controller of the fastening tool disclosed in the specification of U.S. Patent Application Publication No. 2024 / 0066587 slows down the motor when the fastener holding portion reaches within a prescribed distance from the prescribed home position in the return process of the fastener holding portion (pin holding portion). Then, the controller stops the motor when the fastener holding portion is detected by a Hall sensor to have reached the prescribed home position. SUMMARY

[0003] In the above-described fastening tool, since the motor is slowed down by the Hall sensor before the fastener holding portion reaches the home position, it is possible to reduce the deviation of the position of the fastener holding portion at the actual stop from the home position. However, the sensitivity of the Hall sensor varies due to temperature, individual differences, etc., and thus the position of the fastener holding portion at the actual stop still deviates.

[0004] It is a non-limiting object of the present application to provide a technology that contributes to improving the positioning accuracy of the pin holding portion in the initial state of the fastening tool.

[0005] According to a non-limiting aspect of the present application, there is provided a fastening tool configured in a manner that fastens a work material using a fastener including a pin and a cylindrical portion. The fastening tool has a tool body, a motor, a pin holding portion, a first detection device, a first abutting portion, a second abutting portion, a second detection device, and a control device.

[0006] The motor is housed in the tool body. The pin holding portion is configured to hold the pin. The pin holding portion is coupled to the motor in a movable manner, and is movable relative to the tool body along a drive axis in a prescribed forward and rearward direction of the fastening tool between a most forward position and a most rearward position by the power of the motor. The first detection device is configured to detect a case where the pin holding portion is positioned at a first detection position in the forward and rearward direction between the most forward position and the most rearward position.

[0007] The first abutting portion is configured to move in the front-rear direction with respect to the tool body in conjunction with the pin holding portion. The second abutting portion is provided in the tool body and is configured to abut against the first abutting portion in response to the pin holding portion moving from the rear to the most forward position, thereby positioning the pin holding portion at the most forward position. Further, the first abutting portion can be a part of the pin holding portion or a part of another member linked to the pin holding portion. Likewise, the second abutting portion can be a part of the tool body or a part of another member linked to the tool body. The second detection device is configured to detect the abutment of the first abutting portion against the second abutting portion.

[0008] The control device is configured to control the driving of the motor. The pin holding portion is configured to fasten the work material by the fastener by moving from the most forward position to the rear. The control device is configured to decelerate the motor in response to the first detection device detecting that the pin holding portion has reached the first detection position during the movement of the pin holding portion to the front, and thereafter, stop the motor in response to the second detection device detecting the abutment of the first abutting portion against the second abutting portion. Further, the control device can be implemented by at least one processor / processing circuit, for example.

[0009] In the fastening tool of the present aspect, when the pin holding portion moves to the front to return to the most forward position after the fastening work by the movement of the pin holding portion to the rear, the first abutting portion abuts against the second abutting portion, the pin holding portion is positioned at the most forward position, and the control device stops the motor. That is, the pin holding portion is stopped with the motor in a state where the pin holding portion is physically restricted from moving at the most forward position. Thus, the pin holding portion can be reliably returned to the most forward position. Further, during the movement of the pin holding portion to the front, when the first detection device detects that the pin holding portion has reached the first detection position which is rearward of the most forward position, the control device decelerates the motor. Thus, the impact at the time of the abutment of the first abutting portion against the second abutting portion can be effectively suppressed.

[0010] Further, the control device preferably decelerates the rotational speed of the motor to a prescribed speed suitable for reliably suppressing the impact at least at the point in time when the first abutting portion abuts against the second abutting portion. For example, the control device can continue to decelerate from the first detection position until the first abutting portion abuts against the second abutting portion, and make the rotational speed of the motor at the point in time when the first abutting portion abuts against the second abutting portion be equal to or lower than the prescribed speed. Alternatively, the control device can complete the deceleration before the first abutting portion abuts against the second abutting portion. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a cross-sectional view of a fastening tool. Figure 2 is a partial enlarged view of Figure 1 , in which the illustration of the fastener is omitted. Figure 3 is a cross-sectional view of a fastening tool. Figure 1a further enlarged partial view of Figure 4 is Figure 3 an IV-IV sectional view of the electric machine, showing an initial state where the electric machine is stopped. Figure 5 is Figure 3 a V-V sectional view of the electric machine. Figure 6 is a sectional view corresponding to Figure 4 , showing a state where the pin holding portion reaches a most front position from the rear. Figure 7 is a sectional view corresponding to Figure 3 , showing a state where the pin holding portion reaches a first detection position. Figure 8 is a sectional view corresponding to Figure 4 , showing a state where the pin holding portion reaches a first detection position. Figure 9 is a sectional view corresponding to Figure 3 , showing a state where the pin holding portion reaches a deceleration completion position. Figure 10 is a sectional view corresponding to Figure 4 , showing a state where the pin holding portion reaches a deceleration completion position. Figure 11 is a block diagram showing an electric structure of the tightening tool. Figure 12 is a flowchart of a first control process performed by the pin holding portion at the time of the pulling operation. Figure 13 is an explanatory diagram of changes in the rotational speed and the drive current value of the electric machine in the tightening process. Figure 14 is a flowchart of a second control process performed by the pin holding portion at the time of the returning operation. Figure 15 is a flowchart of the first control process according to another embodiment. [EXPLANATION OF REFERENCE NUMERALS] 1: fastening tool; 10: tool body; 101: outer housing; 105: inner housing; 106: opening; 121: guide plate; 123: guide groove; 145: battery; 16: head portion; 161: anvil; 162: hole; 165: pin holding portion; 166: link member; 17: handle; 170: holding portion; 171: trigger; 172: switch; 175: controller housing portion; 19: recovery 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; 411: driven gear; 412: radial bearing; 413: radial bearing; 42: front side receiving portion; 421: thrust bearing; 425: sleeve; 426: flange portion; 43: rear side receiving portion; 431: thrust bearing; 433: sandwiching member; 434: flange portion; 437: elastic member; 45: screw shaft; 450: drive shaft; 451: extension shaft; 46: rotation-stopping 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: sleeve; Al: drive axis; W: work material. DETAILED DESCRIPTION

[0012] In the non-limiting embodiment of the present application, the control device can be configured to reduce the rotational speed of the motor to a predetermined speed in response to detection by the first detection device that the pin holding portion has reached the first detection position, and thereafter drive the motor at the predetermined speed until the first abutment portion and the second abutment portion are detected by the second detection device to be in abutment. According to this embodiment, the rotational speed of the motor can be made to be a rotational speed suitable for reliably suppressing an impact at the point in time at which the first abutment portion and the second abutment portion are in abutment.

[0013] In addition to or instead of the above-described embodiment, the second detection device can be configured to detect a physical quantity related to the driving state of the motor. When the pin holding portion is physically prevented from moving forward of the most forward position by the abutment of the first abutment portion and the second abutment portion, the driving state of the motor changes. Therefore, the detection method of the abutment of the first abutment portion and the second abutment portion is reasonable for detecting a physical quantity related to the driving state of the motor.

[0014] In addition to or in place of the above-described embodiment, the second detection device can be configured to detect at least one of (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 as a physical quantity. When the abutment of the first abutment portion and the second abutment portion physically hinders the pin holding portion from moving forward of the most forward position, the motor stops and the load applied to the motor sharply increases. Thus, by using at least one of the above-described (i) to (iv), the abutment of the first abutment portion and the second abutment portion can be appropriately detected.

[0015] In addition to or in place of the above-described embodiment, the first detection device can be a magnetic sensor. According to this embodiment, the pin holding portion being located at the first detection position can be detected by a simple mechanism.

[0016] In addition to or in place of the above-described embodiment, the motor can be a three-phase brushless motor. The control device can be configured to decelerate the motor by causing a braking force by short-circuiting between terminals of at least two phases. According to this embodiment, the magnitude of the braking force can be appropriately adjusted by varying the number of short-circuited phases and / or the short-circuiting time.

[0017] In addition to or in place of the above-described embodiment, the control device can be configured to decelerate the motor by changing a duty ratio for PWM control of the motor. According to this embodiment, the motor can be appropriately decelerated by simple control.

[0018] In addition to or in place of the above-described embodiment, the rotational speed of the motor after deceleration can be a low speed that is 20% lower than the rotational speed before deceleration. According to this embodiment, the rotational speed before deceleration can be set relatively high in consideration of work efficiency, while the impact at the time of collision of the first abutment portion and the second abutment portion is suppressed.

[0019] In addition to or in place of the above-described embodiment, the rotational speed after deceleration can be set in such a manner that the stress at the abutment of the first abutment portion and the second abutment portion does not exceed the fatigue limit of the first abutment portion and the second abutment portion. According to this embodiment, the possibility of damage to the first abutment portion and the second abutment portion can be effectively reduced.

[0020] In addition to or instead of the above-described embodiments, the fastening tool can further have a screw feed mechanism coupled in an operable manner to the motor and the pin gripping portion. The screw feed mechanism can include a nut member and a shaft member. The nut member can be supported in the tool body in a manner rotatable about the drive axis and configured to be rotationally driven by the motor. The shaft member can be coupled in an operable manner to the nut member in a manner to move linearly in the front-rear direction in conjunction with the pin gripping portion. The shaft member can have a rotation-preventing portion configured to prevent rotation about the drive axis by being coupled to the tool body. A portion of the rotation-preventing portion can constitute a first abutting portion. According to this embodiment, a rational first abutting portion using the rotation-preventing portion required for the screw feed mechanism used in driving the pin gripping portion can be achieved.

[0021] In addition to or instead of the above-described embodiments, the fastening tool can further have a reaction force receiving portion disposed between the nut member and the first abutting portion in the front-rear direction and configured to receive a reaction force acting on the nut member in the rearward direction when the shaft member moves in the forward direction. A portion of the reaction force receiving portion can constitute a second abutting portion. According to this embodiment, a rational second abutting portion using the reaction force receiving portion of the nut member can be achieved.

[0022] In addition to or instead of the above-described embodiments, the fastening tool can further have a third detection device, a third abutting portion, and a fourth abutting portion. The third detection device can be configured to detect a second detection position of the pin gripping portion in the front-rear direction between the first detection position and the rearmost position. The third detection device can be a magnetic sensor, like the first detection device.

[0023] The third abutting portion can be configured to move in the front-rear direction in conjunction with the pin gripping portion relative to the tool body. The fourth abutting portion can be provided in the tool body and configured to position the pin gripping portion at the rearmost position by abutting against the third abutting portion in response to the pin gripping portion moving from the front to the rearmost position. The third abutting portion can be a portion of the pin gripping portion or a portion of another member coupled to the pin gripping portion. Similarly, the fourth abutting portion can be a portion of the tool body or a portion of another member coupled to the tool body. The second detection device can be further configured to detect abutment of the third abutting portion and the fourth abutting portion.

[0024] The control device can be configured to decelerate the motor in response to detection by the third detection device that the pin gripping portion has reached the second detection position during movement of the pin gripping portion in the rearward direction, and then stop rotation of the motor in response to detection by the second detection device that the third abutment portion and the fourth abutment portion are in abutment.

[0025] According to this embodiment, the fastening tool operates in the same manner as when the pin gripping portion moves in the forward direction even when the pin gripping portion moves in the rearward direction. That is, the fastening work is performed while the pin gripping portion moves in the rearward direction, and when the last rearward position is reached, the third abutment portion and the fourth abutment portion are in abutment, the pin gripping portion is positioned at the last rearward position, and the control device stops the motor. That is, the motor is stopped with the pin gripping portion physically restricted from moving in the last rearward position. Thus, the pin gripping portion can be reliably positioned at the last rearward position. In addition, during movement of the pin gripping portion in the rearward direction, when the third detection device detects that the pin gripping portion has reached the second detection position that is forward of the last rearward position, the control device decelerates the motor. Thus, the impact when the third abutment portion and the fourth abutment portion collide can be effectively suppressed. Furthermore, the deceleration method during movement of the pin gripping portion in the rearward direction can be substantially the same as the deceleration method during movement of the pin gripping portion in the forward direction, or can be different.

[0026] Hereinafter, representative and non-limiting embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0027] <First Embodiment> The fastening tool 1 according to the first embodiment will be described with reference to FIG. 1. The fastening tool 1 is an example of an electric power tool that can perform a fastening work using a fastener. Figures 1-14

[0028] The fastening tool 1 can selectively use a plurality of fasteners. Figure 1 The fastener 9 shown is an example of a fastener that can be used in the fastening tool 1. More specifically, the fastener 9 is an example of a well-known fastener called a multi-piece sleeve type fastener.

[0029] Hereinafter, the structure of the fastener 9 will be described briefly. The fastener 9 includes a pin 91 and a sleeve 95. The pin 91 includes a shaft portion and a head formed integrally with one end portion of the shaft portion. The sleeve 95 is a cylindrical member that can be inserted through the shaft portion. The pin 91 and the sleeve 95 are originally formed separately from each other. By the fastening tool 1, the pin 91 is pulled in the axial direction with respect to the sleeve 95, whereby the sleeve 95 is deformed, and the work material W is fastened by the head of the pin 91 and the sleeve 95 pressed against the shaft portion of the pin 91.

[0030] Hereinafter, the general structure of the fastening tool 1 will be described.

[0031] As​Figure 1 As shown in the figure, the fastening tool 1 has a tool body 10, a head portion 16, and a handle 17.

[0032] The tool body 10 is a hollow body also called a case. In the tool body 10, a motor 21, a drive mechanism 3, and the like are housed. The head portion 16 has a cylindrical anvil 161 and a pin holding portion 165 disposed inside the anvil 161. The anvil 161 is fixedly joined to an end portion of the tool body 10 in a manner extending along a prescribed drive axis Al. The pin holding portion 165 is movably joined to the drive mechanism 3 and is movable with respect to the anvil 161 along the drive axis Al. On the end portion of the tool body 10 opposite the anvil 161 in the direction of extension of the drive axis Al, a recovery container 19 capable of housing pin tails separated in the fastening process is detachably installed.

[0033] The handle 17 is an elongated cylindrical body configured to be held by the user. The handle 17 extends from the tool body 10 in a cantilevered manner in a direction intersecting (more specifically, substantially orthogonal to) the drive axis Al. The handle 17 has a trigger 171 that is pressed by the user. On the free end of the handle 17, a battery 145 is detachably installed. The fastening tool 1 operates on power supplied from the battery 145.

[0034] Hereinafter, with respect to the directions of the fastening tool 1, the direction of extension of the drive axis Al is defined as the front-rear direction of the fastening tool 1 for ease of explanation. In the front-rear direction, the side on which the head portion 16 is disposed is defined as the front side, and the opposite side (on which the recovery container 19 is disposed) is defined as the rear side. In addition, the direction orthogonal to the drive axis Al and corresponding to the long axis direction of the handle 17 is defined as the up-down direction. In the up-down direction, the side of the handle 17 joined to the tool body 10 is defined as the upper side, and the opposite side (the free end side of the handle 17) is defined as the lower side. In addition, the direction orthogonal to the front-rear direction and the up-down direction is defined as the left-right direction.

[0035] When the user engages a portion of the shaft portion of the pin 91 of the fastener 9 with the opening of the tip portion of the anvil 161 and performs a pressing operation on the trigger 171, the motor 21 is driven. The drive mechanism 3 is driven by the power of the motor 21, and the pin holding portion 165 holds the pin 91 and forcibly pulls it rearward with respect to the sleeve 95, whereby the fastener 9 is deformed and the work material W is fastened. A portion (pin tail) of the shaft portion of the pin 91 is torn off and separated from the fastener 9. Thereafter, the pin holding portion 165 is returned to the front by the drive mechanism 3, and the series of operations of the fastening process ends. Hereinafter, the operation of moving the pin holding portion 165 rearward is also referred to as a pulling operation, and the operation of moving the pin holding portion 165 forward is referred to as a return operation.

[0036] Next, details of the physical structure of the fastening tool 1 will be described.

[0037] First, the tool body 10 and the constituent elements arranged inside thereof will be described.

[0038] As shown in Figure 1 , the tool body 10 includes an outer case 101 and an inner case 105. The outer case 101 is formed in a substantially rectangular box shape and extends along the drive axis Al. The inner case 105 is formed in a substantially cylindrical shape and is held in a fixed manner in the outer case 101 in the front half of the upper half of the outer case 101. Further, in the present embodiment, the outer case 101 is formed of resin integrally with the handle 17, whereas the inner case 105 is formed of metal.

[0039] As shown in Figure 2 , in the inside of the tool body 10, mainly the motor 21, the drive mechanism 3, and the position detection mechanism 8 are accommodated.

[0040] The motor 21 is accommodated in the lower rear end portion of the tool body 10. The motor 21 of the present embodiment is a three-phase brushless DC motor. The rotational axis of the motor shaft 211 extends in parallel with the drive axis Al (i.e., in the front-rear direction) on the lower side of the drive axis Al. The motor shaft 211 is rotatable in two directions, a forward direction and a reverse direction. The forward direction corresponds to a direction in which the lead screw shaft 45 and the pin gripping portion 165 described later are moved rearward. The reverse direction corresponds to a direction in which the lead screw shaft 45 and the pin gripping portion 165 are moved forward.

[0041] The drive mechanism 3 is linked to the motor 21 in an operable manner. The drive mechanism 3 is configured to move the pin 91 of the fastening member 9 relative to the sleeve 95 in the front-rear direction by the power of the motor 21. More specifically, the drive mechanism 3 is configured to move the pin gripping portion 165 gripping the pin 91 relative to the tool body 10 and the anvil 161 along the drive axis Al.

[0042] The drive mechanism 3 of the present embodiment includes a planetary reducer 31, a drive gear 32, and a ball screw mechanism 4.

[0043] The planetary reducer 31 is arranged on the front side of the motor 21 in a coaxial manner with the motor 21 in the lower half of the tool body 10. The drive gear 32 is arranged on the front side of the planetary reducer 31 in a coaxial manner with the planetary reducer 31. The planetary reducer 31 is configured to increase the torque input from the motor shaft 211 to rotate the drive gear 32.

[0044] The ball screw mechanism 4 is a motion conversion mechanism configured in such a manner as to convert rotational motion into linear motion. As shown in Figure 3 and Figure 4As shown, the ball screw mechanism 4 is configured with a nut 41 and a screw shaft 45 as a main body. In the present embodiment, the ball screw mechanism 4 is configured to convert the rotational motion of the nut 41 into the linear motion of the screw shaft 45, and to move the pin holding portion 165 linearly. The ball screw mechanism 4 is housed in the upper half of the tool main body 10.

[0045] The nut 41 is supported to the tool main body 10 in a state where it cannot substantially move in the front-rear direction and can rotate around the drive axis line Al. In the present embodiment, the nut 41 is housed in the inner housing 105. The nut 41 is formed in a cylindrical shape, and has a driven gear 411 integrally provided in the outer peripheral portion. The nut 41 is supported by two radial bearings 412, 413 supported to the tool main body 10 on the front side and the rear side of the driven gear 411. The driven gear 411 is engaged with the drive gear 32.

[0046] The screw shaft 45 is engaged with the nut 41 with respect to the tool main body 10 in a state where it cannot substantially rotate around the drive axis line Al and can move in the front-rear direction along the drive axis line Al. More specifically, the screw shaft 45 is configured as an elongated body, and is inserted through the nut 41 in a manner extending along the drive axis line Al. Although detailed illustration is omitted, a helical track is defined by grooves respectively formed in the inner peripheral surface of the nut 41 and the outer peripheral surface of the screw shaft 45. A plurality of balls are arranged in a manner capable of rolling within the track. The screw shaft 45 is engaged with the nut 41 via the balls.

[0047] The rear end portion of the screw shaft 45 protrudes toward the rear of the inner housing 105 by passing through the opening 106 of the rear wall portion of the inner housing 105 in the front-rear direction. In the rear end portion of the screw shaft 45, an extension shaft 451 is coaxially joined and fixed, and forms an integral body with the screw shaft 45. Hereinafter, the screw shaft 45 and the extension shaft 451 that form an integral body will be collectively referred to as a drive shaft 450.

[0048] The drive shaft 450 has a through-hole that passes through the drive shaft 450 along the drive axis line Al. In the rear end portion of the tool main body 10, a recovery container 19 (refer to Figure 1 ) is detachably installed. The pin tail separated from the fastener 9 reaches the recovery container 19 by passing through the through-hole of the drive shaft 450, and is housed in the recovery container 19.

[0049] As Figures 3-5As shown, a rotation-stopping member 46 is coupled to the drive shaft 450 in a non-movable manner so as to be integral with the drive shaft 450. The rotation-stopping member 46 is configured around the rear end portion of the lead screw shaft 45, and includes a base portion 461 fixed to the lead screw shaft 45 and two arm portions 465 extending from the base portion 461 to the left and right, respectively. A bearing 466 is installed at the tip end portion of each arm portion 465. On the other hand, a pair of guide plates 121 is 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.

[0050] The rotation-stopping member 46 is prevented from rotating around the drive axis Al by the bearings 466 engaging with the guide plates 121 when the drive shaft 450 is also rotated by the torque of the nut 41. Thus, as the nut 41 rotates around the drive axis Al in response to the driving of the motor 21, the drive shaft 450 moves linearly in the front-rear direction relative to the nut 41 and the tool body 10.

[0051] A magnet holder 47 that holds the magnet 48 is fixed to the upper end portion of the rotation-stopping member 46. That is, the magnet holder 47 and the magnet 48 are integral with the drive shaft 450 via the rotation-stopping member 46. The magnet holder 47 holds the magnet 48 so that the magnet 48 is exposed upward. The magnet 48 moves in the front-rear direction along a movement axis parallel to the drive axis Al as the drive shaft 450 moves in the front-rear direction along the drive axis Al.

[0052] The position detection mechanism 8 is a mechanism that detects the position of the pin gripping portion 165 by detecting the magnetic field of the magnet 48, and thereby detecting the drive shaft 450. As shown in FIG. 2, the position detection mechanism 8 includes a magnet 48 and a pair of magnetic sensors 80 (a first sensor 81 and a second sensor 82) disposed in the vicinity of the movement axis of the magnet 48. Figure 3 As shown, in the present embodiment, the position detection mechanism 8 includes two magnetic sensors 80 (a first sensor 81 and a second sensor 82) disposed separately in the front-rear direction in the vicinity of the movement axis of the magnet 48.

[0053] 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 disposed within the detection range of the magnetic sensor 80. Figure 1 The detection result of the magnetic sensor 80 is used for the driving control of the motor 21, and further for the movement control of the pin gripping portion 165. The control based on the detection result of the magnetic sensor 80 will be described in detail later.

[0054] As shown in FIG. 2, the magnet 48 is disposed in the vicinity of the movement axis of the drive shaft 450. The magnet 48 is disposed so as to be exposed upward from the upper end portion of the rotation-stopping member 46. Figure 3 and Figure 4As shown, a front-side receiving portion 42 and a rear-side receiving portion 43 are provided on the front side and the rear side of the nut 41, and are configured to receive loads (thrust loads) in the axial direction of the nut 41, respectively.

[0055] The front-side receiving portion 42 includes a thrust bearing 421 disposed between the front end of the nut 41 and the front end portion of the tool body 10 (specifically, the inner housing 105) in the front-rear direction. The thrust bearing 421 is provided to allow rotation of the nut 41 while receiving a reaction force in the forward direction that acts on the nut 41 when the drive shaft 450 and the pin gripping portion 165 move in the rearward direction relative to the tool body 10.

[0056] The thrust bearing 421 is fitted around and supported by a cylindrical sleeve 425. The sleeve 425 has a flange portion 426 protruding to the radial outer side at the front end thereof. The sleeve 425 is held in a fixed manner to the tool body 10 in a state in which the flange portion 426 is fitted into the inner housing 105.

[0057] The rear-side receiving portion 43 is disposed between the rear end of the nut 41 and the rear end portion of the tool body 10 (specifically, the inner housing 105) in the front-rear direction. The rear-side receiving portion 43 includes a thrust bearing 431, a clamping member 433, and an elastic member 437.

[0058] 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 rotation of the nut 41 while receiving a reaction force in the rearward direction that acts on the nut 41 when the drive shaft 450 and the pin gripping portion 165 move in the forward direction relative to the tool body 10.

[0059] The clamping member 433 is clamped between the thrust bearing 431 and the rear end portion of the tool body 10 (specifically, the inner housing 105) in the front-rear direction. In the present embodiment, the clamping member 433 is formed as a cylindrical member having a flange portion 434 at the central portion. The clamping member 433 is disposed in the inner housing 105 in a state in which the lead screw shaft 45 is coaxially inserted therethrough. The thrust bearing 431 is fitted around the front end portion of the clamping member 433.

[0060] The elastic member 437 is clamped between the flange portion 434 of the clamping member 433 and the rear end portion of the tool body 10 (specifically, the inner housing 105) in the front-rear direction. In the present embodiment, an O-ring made of rubber is used as the elastic member 437. The elastic member 437 elastically deforms when a force that moves the nut 41 in the rearward direction relative to the tool body 10 acts, thereby allowing the nut 41 and the clamping member 433 to move slightly in the rearward direction relative to the tool body 10.

[0061] More specifically, the elastic member 437, in a pressurized state (slightly compressed state), is positioned between the flange 434 and the rear end of the inner housing 105. Thus, the clamping member 433, the thrust bearing 431, and the nut 41 are forced forward relative to the tool body 10 via the elastic member 437. When the drive shaft 450 is stopped, the clamping member 433 is held in a position where the front surface of the flange 434 abuts against the thrust bearing 431 and the rear surface of the flange 434 is slightly separated forward from the front surface of the rear wall of the inner housing 105. Furthermore, the front end of the nut 41 is held in a position abutting against the rear surface of the rear track ring of the thrust bearing 421 of the front receiving portion 42.

[0062] Furthermore, the cylindrical rear end of the clamping member 433 is slidably disposed within the opening 106 of the rear wall of the inner housing 105. With the drive shaft 450 stopped (no force is substantially applied rearward to the nut 41), the rear end of the clamping member 433 is positioned approximately at the same position as, or slightly forward of, the rear end of the opening 106 of the inner housing 105 in the longitudinal direction. This position of the clamping member 433 is referred to as the foremost position of the clamping member 433.

[0063] On the other hand, when the drive shaft 450 moves forward relative to the tool body 10, it exerts a rearward reaction force on the nut 41, such as Figure 6 As shown, the nut 41, thrust bearing 431, and clamping member 433 move slightly rearward relative to the tool body 10 while compressing the elastic member 437. Consequently, the rear end of the clamping member 433 protrudes slightly rearward from the rear end of the opening 106 of the inner housing 105. This position of the clamping member 433 is referred to as the protruding position of the clamping member 433.

[0064] As the drive shaft 450 moves forward, the rear end of the clamping member 433, located in the protruding position, abuts against the front surface of the base 461 of the anti-rotation member 46, thereby preventing the drive shaft 450 from moving further forward. That is, the anti-rotation member 46 and the clamping member 433 work together to function as a positioning part or stop that positions the drive shaft 450, and thus the pin holding part 165, relative to the tool body 10 at the foremost position.

[0065] Furthermore, in this embodiment, the inner housing 105 is made of aluminum to reduce its weight, while the anti-rotation member 46 and the clamping member 433 that abut against each other are made of iron to ensure strength.

[0066] The following describes the nose section 16.

[0067] like Figure 2As shown, the machine head 16 is mainly composed of an anvil 161 and a pin holding part 165. Furthermore, since the structure of the anvil 161 and the pin holding part 165 is known, it will be briefly described below.

[0068] The anvil 161 is cylindrical in shape and has a hole 162 extending along the drive axis A1. The top end of the hole 162 can engage with the sleeve 95 of the fastener 9 (see reference). Figure 1 The anvil 161 is detachably connected to the front end of the tool body 10 (inner housing 105) via a connecting member.

[0069] The pin holding portion 165 is configured to hold the pin 91 (shaft portion) of the fastener 9 and is held so as to be movable in the front-rear direction relative to the anvil 161 along the drive axis A1. More specifically, the pin holding portion 165 is held coaxially with the anvil 161 within a hole 162 and is able to slide within the hole 162. The pin holding portion 165 has multiple claws capable of holding the shaft portion of the pin 91. The pin holding portion 165 is configured such that the holding force of the claws increases as it moves rearward relative to the anvil 161.

[0070] The rear end of the pin holding portion 165 is connected to the front end of the lead screw shaft 45 via the connecting member 166. Therefore, the pin holding portion 165 and the lead screw shaft 45 (drive shaft 450) move integrally in the front-rear direction. The pin holding portion 165 and the connecting member 166 extend along the drive axis A1, defining a channel communicating with the through hole of the drive shaft 450. The pin tail, separated from the fastener 9, passes through the pin holding portion 165, the connecting member 166, and the drive shaft 450 and is received in the recovery container 19.

[0071] Furthermore, the diameter of the rear end of the connecting member 166 is larger than that of the lead screw shaft 45, allowing it to slide within the hole 162 of the anvil 161. The flange 426 of the 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. That is, the sleeve 425 and the connecting member 166 work together to function as a positioning part or stop that positions the drive shaft 450, and consequently the pin holding part 165, relative to the tool body 10 at the rearmost position. In addition, the connecting member 166 and the sleeve 425, which abut against each other, are also made of iron to ensure strength.

[0072] The handle 17 and the constituent elements disposed therein will now be described.

[0073] like Figure 1 As shown, the portion of the handle 17 other than its lower end is configured as a gripping portion 170, having a thickness suitable for gripping. On the other hand, the lower end of the handle 17 is formed into a rectangular box shape to house the controller 20. Hereinafter, the lower end of the handle 17 will also be referred to as the controller housing portion 175.

[0074] A trigger 171 is provided on the front side of the upper end of the handle 17 (grip portion 170). A switch 172 is housed in the upper end of the grip portion 170. The switch 172 is configured to be always maintained in an off state, and is turned on during the period when the trigger 171 is pressed.

[0075] The controller 20 is a control device configured in such a manner as to control the operation of the fastening tool 1 (for example, the driving of the motor 21), and includes at least one processor / processing circuit and at least one memory mounted on a circuit board. Further, the controller 20 of the present embodiment is configured as a microcomputer including a CPU, a ROM, a RAM, and the like. The controller 20 is electrically connected to the magnetic sensor 80 (refer to Figure 2 ), the switch 172, and the like via an electric wire not shown.

[0076] Hereinafter, the operation of the pin grip portion 165 and the position detection by the magnetic sensor 80 (first sensor 81 and second sensor 82) of the position detection mechanism 8 will be described. Further, as described above, since the drive shaft 450 and the pin grip portion 165 move integrally, the operation of the pin grip portion 165 is synonymous with the operation of the drive shaft 450.

[0077] As described above, the pin grip portion 165 is movable between the foremost position and the rearmost position in the movable range in the front-rear direction thereof. However, normally, the pin grip portion 165 moves between the foremost position and a rear stop position which is forward of the rearmost position.

[0078] More specifically, as shown in Figure 6 , when the pin grip portion 165 moves forward (at the time of return operation), the pin grip portion 165 moves forward before the front surface of the base portion 461 of the rotation-stopping member 46 abuts against the rear end of the sandwiching member 433 disposed in the projected position, and is positioned at the foremost position. Thereafter, when the motor 21 is stopped and the movement of the pin grip portion 165 becomes a stopped state, as shown in Figure 4 , the sandwiching member 433 returns to the foremost position by the force of the elastic member 437. Therefore, in the state where the pin grip portion 165 is positioned at the foremost 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 rotation-stopping member 46 is positioned at a position slightly separated rearward from the rear end of the sandwiching member 433 and the rear wall portion of the inner housing 105.

[0079] The first sensor 81 of the position detection mechanism 8 is provided to detect the pin grip portion 165 when the pin grip portion 165 is positioned at a prescribed position (hereinafter, referred to as a first detection position) which is rearward of the foremost position. More specifically, the first sensor 81 is disposed to be able to detect the position of the magnet 48 in response to the pin grip portion 165 reaching the first detection position during the movement thereof in the forward direction. In the present embodiment, as shown inFigure 7 As shown, when the pin holding part 165 is in the first detection position, the magnet 48 is substantially located directly below the first sensor 81. Additionally, as... Figure 8 As shown, when the pin holding part 165 is in the first detection position, the anti-rotation part 46 is located at a position that separates from the rear end of the clamping part 433 and the rear wall of the inner housing 105.

[0080] When the first sensor 81 detects the magnet 48, it outputs a detection signal to the controller 20. In this embodiment, the controller 20 is configured such that when it receives the detection signal from the first sensor 81 during the return movement of the pin gripping part 165, it reduces the rotational speed of the motor 21 to a predetermined speed before the pin gripping part 165 reaches its foremost position, and then maintains the reduced speed. Hereinafter, the position where the rotational speed of the motor 21 reaches the predetermined speed will be referred to as the deceleration completion position of the pin gripping part 165. Figure 9 and Figure 10 As shown, when the pin holding part 165 is in the deceleration completed position, the anti-rotation part 46 is located in a position further forward than when the pin holding part 165 is in the first detection position, but it is still separated from the rear end of the clamping part 433 and the rear wall of the inner housing 105.

[0081] On the other hand, in this embodiment, when the pin holding part 165 moves backward (during the pulling action), it stops at a rear stop position that is forward of the rearmost position.

[0082] The second sensor 82 is configured to detect the pin holding portion 165 when it is located at a predetermined position (hereinafter referred to as the second detection position) that is forward of both the rearmost and rearmost stopping positions. More specifically, the second sensor 82 is positioned behind the first sensor 81 to detect the position of the magnet 48 in response to the pin holding portion 165 reaching the second detection position during rearward movement. Although not illustrated, in this embodiment, when the pin holding portion 165 is located at the second detection position, the magnet 48 is substantially directly below the second sensor 82. Furthermore, the second detection position of the pin holding portion 165 is set to a position that is further rearward than the position of the pin holding portion 165 when the tail of the pin 91, which is forcefully pulled rearward by the pin holding portion 165, is torn off.

[0083] Furthermore, in this embodiment, the first sensor 81 and the second sensor 82 are mounted on a common circuit board and arranged above the moving axis of the magnet 48 in a manner opposite to the moving axis. However, the first sensor 81 and the second sensor 82 may be mounted on different circuit boards.

[0084] When the second sensor 82 detects the magnet 48, it outputs a detection signal to the controller 20. Details will be explained later, but in this embodiment, when the controller 20 recognizes the detection signal from the second sensor 82 during the pulling action of the pin holding part 165, it causes the motor 21 to stop rapidly. During the period until the motor 21 decelerates and comes to a complete stop, the pin holding part 165 moves slightly rearward and stops at the rearward stop position.

[0085] Furthermore, due to some malfunction, the second sensor 82 may fail to detect when the pin holding part 165 reaches the second detection position during the pulling action. In this case, the sleeve 425 abuts against the connecting part 166, preventing the pin holding part 165 from moving further rearward than its rearmost position.

[0086] The electrical structure of fastening tool 1 will be described below.

[0087] like Figure 11 As shown, 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 has a three-phase bridge circuit using six semiconductor switching elements, and each switching element of the three-phase bridge circuit switches according to the duty cycle indicated by the control signal from the controller 20. The Hall sensor 203 has three Hall elements arranged corresponding to each of the motors 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.

[0088] In addition, the current sensing amplifier 205 is electrically connected to the controller 20. The current sensing amplifier 205 converts the drive current of the motor 21 into voltage through a shunt resistor, and outputs the amplified signal to the controller 20.

[0089] Furthermore, the controller 20 is electrically connected to the switch 172 of the trigger 171, the first sensor 81, and the second sensor 82. In this embodiment, the controller 20 is configured to control the rotational speed of the motor 21 via PWM control. The controller 20 controls the drive of the motor 21 appropriately based on the signals output from the switch 172, the first sensor 81, the second sensor 82, and the current detection amplifier 205, thereby controlling the operation of the drive mechanism 3 and, consequently, the movement of the pin holding part 165.

[0090] The control process of the motor 21 of the fastening tool 1 will be explained below.

[0091] First, refer to Figure 12 and Figure 13The control processing of the motor 21 during the pulling action of the pin holding part 165 (hereinafter referred to as the first control processing) will be explained. The first control processing begins in response to the user pressing the trigger 171, which turns on the switch 172. The controller 20 (specifically, the CPU) executes the first control processing by reading and executing a program stored in a memory (e.g., ROM). Furthermore, in the following description and the flowcharts referred to, "step" will be abbreviated as "S".

[0092] At the start time of the first control process ( Figure 13 At time t0), the pin holding part 165 is in the foremost position (refer to...). Figure 3 , Figure 4 ).like Figure 12 As shown, when the first control process begins, the controller 20 sets the duty cycle for PWM control in order to drive the motor 21 at a predetermined rotational speed. Furthermore, in this embodiment, considering the efficiency of the fastening operation, the rotational speed during the pulling action is determined to be the maximum speed of the motor 21, and the duty cycle is set to 100% (S110). However, in other embodiments, the rotational speed during the pulling action and the corresponding duty cycle can be appropriately changed.

[0093] The controller 20 drives the motor 21 at a set duty cycle (S120). During the pulling action, the rotation direction of the motor shaft 211 is positive. The drive mechanism 3 is driven, and the pin holding part 165, which is holding the pin 91 of the fastener 9, moves 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).

[0094] While the motor 21 is driven (i.e., while the pin holding part 165 moves backward), the controller 20 monitors the detection signal output from the second sensor 82 (S130). During the period when no detection signal is detected from the second sensor 82 (i.e., during the period when the pin holding part 165 has not reached the second detection position), the controller 20 continues to drive the motor 21 at the highest speed (S130: No, S110, S120). During this period, the pin holding part 165 moves backward while pulling the pin 91, and the working material W is secured by the fastener 9. As described above, the pin tail is pulled off before the pin holding part 165 reaches the second detection position.

[0095] When the pin holding 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 can be stopped, for example, by stopping the energization to the motor 21 alone. Alternatively, the motor 21 can be braked in order to stop the motor 21 quickly. In the present embodiment, the controller 20 generates the maximum braking force by short-circuiting all the terminals of the three phases, thereby stopping the motor 21 in the shortest time (the interval from time t2 to t3). With the complete stop of the rotation of the motor 21 (time t3), the pin holding portion 165 is stopped at the rear stop position, and the pulling action of the pin holding portion 165 is thus ended.

[0096] Further, although not explicitly shown as a step in the flowchart, in the present embodiment, the controller 20, in the case where the press of the trigger 171 is released and the switch 172 is turned off in the first control process, transfers the process to S140 to stop the motor 21 and end the first control process, and transfers to the second control process described later.

[0097] Next, the control process of the motor 21 at the time of the return action of the pin holding portion 165 (hereinafter referred to as the second control process) will be described with reference to Figure 13 and Figure 14 The second control process is started in response to the press of the trigger 171 being released by the user and the switch 172 being switched from on to off after the end of the first control process described above. As with the first control process, the controller 20 (in detail, the CPU) executes the second control process by reading out and executing a program stored in a memory (for example, a ROM).

[0098] As described above, at the start time point of the second control process (time t4 of Figure 13 ), the pin holding portion 165 is located at the rear stop position. As shown in Figure 14 , when the second control process is started, the controller 20 sets the duty ratio for PWM control in order to drive the motor 21 at a predetermined first rotation speed. Further, in the present embodiment, the first rotation speed at the time of the return action is determined to be the highest speed of the motor 21 in consideration of the efficiency of the tightening work, and the duty ratio is set to 100% (S210). However, in other embodiments, the first rotation speed and the corresponding duty ratio can be changed as appropriate.

[0099] The controller 20 drives the motor 21 at the set duty ratio (S220). The direction of the rotation of the motor shaft 211 at the time of the return action is the reverse direction. The drive mechanism 3 is driven, and the pin holding portion 165 moves forward. The rotation speed of the motor 21 rises to the first rotation speed (the highest speed) (the interval from time t4 to t5), and is maintained at the highest speed (the interval from time t5 to t6).

[0100] The controller 20 monitors the signal output from the first sensor 81 in the driving of the motor 21 (i.e., the movement of the pin holding portion 165 in the forward direction) (S230). During a period in which the detection signal from the first sensor 81 is not recognized (i.e., a period in which the pin holding portion 165 does not reach the first detection position), the controller 20 continues to drive the motor 21 at the highest speed (S230: No, S210, S220).

[0101] When the pin holding portion 165 reaches the first detection position (refer to Figure 7 , Figure 8 ), the detection signal is output from the first sensor 81 (S230: Yes), the controller 20 decelerates the motor 21 to a predetermined second rotational speed (i.e., reduces the rotational speed of the motor 21) (S240). The second rotational speed is a low speed lower than the first rotational speed.

[0102] Further, in the present embodiment, as described above, the movement of the pin holding portion 165 in the forward direction is completely stopped at the most forward position by the abutment of the sandwiching member 433 and the rotation-stopping member 46. Thus, in order to suppress the impact due to the collision of the sandwiching member 433 and the rotation-stopping member 46, it is preferable that the second rotational speed be less than 20% of the first rotational speed. In the present embodiment, the second rotational speed is determined to be 10% of the first rotational speed, i.e., the highest rotational speed of the motor 21. Thus, the first rotational speed is set as the highest speed in consideration of work efficiency, while the impact at the time of the collision of the sandwiching member 433 and the rotation-stopping member 46 can be effectively suppressed.

[0103] In addition, in the present embodiment, the second rotational speed is set so that the stress at the abutment of the sandwiching member 433 and the rotation-stopping member 46 does not exceed the fatigue limit of the sandwiching member 433 and the rotation-stopping member 46. Thus, the possibility of damage to the sandwiching member 433 and the rotation-stopping member 46 can be effectively reduced.

[0104] The deceleration in S240 is performed, for example, by generating a braking force by short-circuiting between terminals of at least two of the three phases of the motor 21 (by using a so-called short-circuit brake). The magnitude of the braking force can be adjusted by varying the number of phases that are short-circuited and / or the short-circuit time. In the present 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, when the pin holding portion 165 reaches the deceleration completion position (refer to Figure 9 , Figure 10 ), the rotational speed of the motor 21 reliably decreases to the second rotational speed. Further, the deceleration completion position of the pin holding portion 165 is set to a position that is a prescribed distance rearward from the most forward position (refer to Figure 6 ).

[0105] In this embodiment, in S240, the controller 20 generates maximum braking force by short-circuiting all terminals of the three phases, thereby decelerating the motor 21 to the second rotational speed (between time t6 and t7) in the shortest time (shortest distance). This maximizes the time for the return motion, where the motor 21 is driven at the first rotational speed (maximum speed), thus optimizing work efficiency.

[0106] Furthermore, in other embodiments, the deceleration in S240 is achieved, for example, by reducing the duty cycle used in PWM control. The controller 20 may, for example, change the duty cycle in a manner that reduces the rotational speed of the motor 21 at a constant rate of change (linearly). Alternatively, the controller 20 may change the duty cycle in a manner that reduces it in a quadratic or exponential manner (non-linearly).

[0107] The controller 20 goes into standby mode before the actual rotational speed of the motor 21, which is specific to the signal from the Hall sensor 203, decreases to the second rotational speed (S250). When the actual rotational speed of the motor 21 reaches the second rotational speed (time t7), the controller 20 sets the duty cycle to 10% (S260) and continues to drive the motor 21 at the second rotational speed (S270) (between time t7 and t8).

[0108] The controller 20 determines whether the clamping member 433 and the anti-rotation member 46 are in contact (i.e., whether the pin holding part 165 has reached its foremost position) (S280). The contact between the clamping 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 contact between the clamping member 433 and the anti-rotation member 46 obstructs the forward movement of the pin holding part 165, the driving current value of the motor 21 increases sharply, and the rotational speed of the motor 21 decreases sharply. Therefore, the driving current value or the rotational speed of the motor 21 is a suitable physical quantity for determining whether the clamping member 433 and the anti-rotation member 46 are in contact.

[0109] In this embodiment, the rate of change of the drive current value of the motor 21 is detected by the contact between the clamping member 433 and the anti-rotation member 46. More specifically, the controller 20 determines whether the rate of increase of the drive current value of the motor 21 exceeds a predetermined rate of increase based on the signal output from the current detection amplifier 205. During the period when the rate of increase of the drive current value of the motor 21 does not exceed the predetermined rate of increase, the controller 20 continues to drive the motor 21 at a second rotational speed (S280: No, S260, S270).

[0110] Further, in other embodiments, it can be determined whether the drive current value exceeds a predetermined threshold value. Alternatively, it can be determined whether the rotational speed of the motor 21 is lower than a predetermined threshold value. Alternatively, it can be determined whether the reduction rate of the rotational speed of the motor 21 is lower than a predetermined reduction rate.

[0111] The controller 20 stops the motor 21 at the time t8 when it is determined that the sandwich member 433 is in abutment with the rotation-stopping member 46 and the increase rate of the drive current value of the motor 21 exceeds the predetermined increase rate (S280: YES), and ends the second control process (S290). As with S140 of the first control process, the motor 21 can be stopped by merely stopping energization, or the motor 21 can be braked. In the state in which the pin holding portion 165 is positioned at the most forward position, the sandwich member 433 is returned from the protruding position to the most forward position, and the returning action of the pin holding portion 165 ends. Figure 13

[0112] As described above, in the present embodiment, when the pin holding portion is moved forward to be returned to the most forward position, the sandwich member 433 is in abutment with the rotation-stopping member 46, the pin holding portion 165 is positioned at the most forward position, and the controller 20 stops the motor 21. That is, the motor 21 is stopped in the state in which the pin holding portion 165 is physically hindered from moving forward at the most forward position. Thus, the pin holding portion 165 can be reliably returned to the prescribed most forward position.

[0113] Further, during the movement of the pin holding portion 165 forward, when the first sensor 81 detects that the pin holding portion 165 has reached the first detection position which is rearward of the most forward position, the controller 20 decelerates the motor 21 and further the pin holding portion 165. Since the deceleration of the motor 21 and the pin holding portion 165 is completed before the pin holding portion 165 reaches the most forward position, the rotation-stopping member 46 moves at the decelerated second rotational speed while colliding with the sandwich member 433. Thus, the impact at the time of collision of the sandwich member 433 with the rotation-stopping member 46 can be effectively suppressed.

[0114] <Second Embodiment> A second embodiment of the present application will be described with reference to Figure 15 In the second embodiment, however, a part of the first control process of the motor 21 performed by the controller 20 is different from the first embodiment, but the contents of the processes other than this and the structure of the fastening tool 1 are substantially the same as those of the first embodiment. Thus, in the following, the same step number is annotated for the processes substantially the same as those of the first embodiment and the explanation thereof is omitted or simplified, and only the contents of the processes different from those of the first embodiment will be described.

[0115] ​In the first control process of the present embodiment, the same process as the second control process of the first embodiment is performed. In brief, the controller 20 decelerates the motor 21 from the first rotational speed to the second rotational speed when the pin gripping portion 165 reaches the second detection position. Thereafter, the controller 20 stops the motor 21 when the sleeve 425 comes into abutment with the link member 166 (refer to Figure 2 ) upon the pin gripping portion 165 reaching the rearmost position.

[0116] In more detail, as shown in Figure 15 , when the first control process is started, the controller 20 sets a duty ratio (100%) corresponding to the first rotational speed (the highest speed) at the time of the 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 highest speed during a period in which the detection signal from the second sensor 82 is not recognized (i.e., during a period in which the pin gripping portion 165 does not reach the second detection position) (S130: No, S110, S120).

[0117] When the pin gripping portion 165 reaches the second detection position and the 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 addition, in the present embodiment, the movement of the pin gripping portion 165 is completely stopped by the sleeve 425 coming into abutment with the link member 166. Thus, as with the second rotational speed of the first embodiment, in order to suppress the impact due to the abutment of the sleeve 425 with the link member 166, the second rotational speed of the present embodiment is preferably less than 20% of the first rotational speed (the highest speed) at the time of the start of the pulling operation. In the present embodiment, the rotational speed after deceleration is determined to be 10% of the highest speed of the motor 21.

[0118] In addition, the deceleration method in S131 can be the same as the deceleration method in S240 of the second control process of the first embodiment. For example, the controller 20 decelerates the motor 21 in the shortest time (the shortest distance) by causing the maximum braking force by short-circuiting all of the terminals of the motor 21 in such a manner that the second rotational speed is obtained at a deceleration completion position located between the second detection position and the rearmost position. However, in other embodiments, the deceleration method during the movement of the pin gripping portion 165 to the rearward direction can be different from the deceleration method during the movement of the pin gripping portion 165 to the forward direction.

[0119] The controller 20 stands by until the actual rotational speed of the motor 21 is reduced to the second rotational speed (S132). The controller 20 sets the duty ratio to 10% when the actual rotational speed of the motor 21 reaches the second rotational speed (S133), and continues the drive of the motor 21 at the second rotational speed (S134).

[0120] The controller 20 determines whether the sleeve 425 and the link member 166 are in abutment (i.e., whether the pin holding portion 165 has reached the rearmost position). The abutment of the sleeve 425 and the link member 166 can be detected in the same manner as the abutment of the sandwich member 433 and the rotation-stopping member 46. That is, the controller 20 determines whether the sleeve 425 and the link member 166 are in abutment by whether the rate of increase in the drive current value of the motor 21 exceeds a predetermined rate of increase (S135). The controller 20 continues driving the motor 21 at the second rotational speed during a period in which 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).

[0121] When the controller 20 determines that the sleeve 425 and the link member 166 are in abutment and the rate of increase in the drive current value of the motor 21 exceeds the predetermined rate of increase (S135: Yes), the controller 20 stops the motor 21 (S136), and ends the first control process. As in S290 of the second control process, the motor 21 can be stopped by merely stopping energization, or the motor 21 can be braked. In the state in which the pin holding portion 165 is positioned at the rearmost position, the pin holding portion 165 ends the pulling action.

[0122] As described above, in the present embodiment, the fastening tool 1 operates in the same manner when the pin holding portion 165 moves rearward as when the pin holding portion 165 moves forward. That is, when the pin holding portion 165 performs a fastening operation while moving rearward and reaches the rearmost position, the sleeve 425 and the link member 166 are in abutment, the pin holding portion 165 is positioned at the rearmost position, and the controller 20 stops the motor 21. Thus, the pin holding portion 165 can be reliably positioned at the rearmost position.

[0123] In addition, during the movement of the pin holding portion 165 rearward, when the second sensor 82 detects that the pin holding portion 165 has reached the second detection position, which is forward of the rearmost position, the controller 20 decelerates the motor 21, and further decelerates the pin holding portion 165. Since the deceleration of the motor 21 and the pin holding portion 165 is completed before reaching the rearmost position, the link member 166 collides with the sleeve 425 while moving at the second rotational speed after deceleration. Thus, the impact at the time of the collision of the sleeve 425 and the link member 166 can be effectively suppressed.

[0124] The following shows the correspondence between each of the components (features) of the above-described embodiments and each of the components (features) of the present invention or technical solution. However, each of the components of the embodiments is merely an example, and does not limit each of the components of the present invention or the technical solution.

[0125] The first sensor 81 is an example of the "first detection device". The base portion 461 of the rotation-stopping member 46 is an example of the "first abutting portion". The rear end portion of the sandwiching member 433 is an example of the "second abutting portion". The current detection amplifier 205 is an example of the "second detection device". The controller 20 (in detail, the CPU) is an example of the "control device". The ball screw mechanism 4 is an example of the "screw feed mechanism". The nut 41, the screw shaft 45, and the rotation-stopping member 46 are examples of the "nut member", the "shaft member", and the "rotation stop", respectively. The rear-side receiving portion 43 is an example of the "reaction force receiving portion". The second sensor 82 is an example of the "third detection device". The rear end portion of the link member 166 is an example of the "third abutting portion". The flange portion 426 of the sleeve 425 is an example of the "fourth abutting portion".

[0126] Further, the fastening tool according to the present application is not limited to the fastening tool 1 of the above-described embodiment. For example, the following non-limiting examples of modifications can be made. In addition, at least one of these modifications can be adopted in combination with at least one of the features described in the fastening tool 1 and the technical solutions of the embodiment.

[0127] First, a modification of the structure for positioning the pin holding portion 165 at the foremost position and the rearmost position will be described.

[0128] The first abutting portion and the second abutting portion that abut against each other in response to the pin holding portion 165 reaching the foremost position from the rear are not limited to the rotation-stopping member 46 and the sandwiching member 433. The first abutting portion can be a part of the pin holding portion 165 or can be provided to a member (for example, the extension shaft 451) linked to the pin holding portion 165, as long as it is movable in the front-rear direction integrally with the pin holding portion 165. The second abutting portion can be a part of the tool main body 10 (for example, the rear wall portion of the inner housing 105) or can be provided to a member linked to the tool main body 10, as long as it is capable of positioning the pin holding portion 165 at the foremost position by abutting against the first abutting portion. Further, in the above-described embodiment, although the sandwiching member 433 corresponding to the second abutting portion allows a slight movement in the front-rear direction with respect to the tool main body 10, the second abutting portion can be incapable of moving in the front-rear direction with respect to the tool main body 10.

[0129] As for the third abutting portion and the fourth abutting portion that position the pin holding portion 165 at the rearmost position, the link member 166 and the sleeve 425 are not limited, and can be modified similarly to the first abutting portion and the second abutting portion.

[0130] Next, a modification of the control of the motor 21 corresponding to the structure of the position detection mechanism 8 (the first sensor 81 and the second sensor 82) and the position of the pin holding portion 165 will be described.

[0131] For example, the magnet 48 can be installed at any position as long as it can move integrally with the pin holding portion 165 in the front-rear direction. The positions of the first sensor 81 and the second sensor 82 can be appropriately changed depending on the position of the magnet 48. In addition, the first sensor 81 and the second sensor 82 can be replaced with sensors of other types (for example, optical sensors such as optical interrupters) or mechanical switches.

[0132] In addition, the detection that the pin holding portion 165 reaches the first detection position can use, for example, the rotational speed of the motor 21. In more detail, the controller 20 counts the speed at which the motor 21 rotates (hereinafter, simply referred to as the rotational speed of the motor 21) based on the signal from the Hall sensor 203 after the pin holding portion 165 starts to move rearward from the most forward position (i.e., after the driving of the motor 21 is started). The controller 20 compares the rotational speed after the start of the forward movement of the pin holding portion 165 with the rotational speed during the rearward movement of the pin holding portion 165. The controller 20 can determine that the pin holding portion 165 has reached the first detection position when the difference between the rotational speed after the start of the forward movement and the rotational speed during the rearward movement becomes a predetermined rotational speed. In addition, the controller 20 can determine that the pin holding portion 165 has reached the second detection position when the rotational speed after the start of the rearward movement reaches the predetermined rotational speed.

[0133] In the above-described embodiment, in the second control process for moving the pin holding portion 165 forward to the most forward position, the controller 20 decelerates the pin holding portion 165 at a deceleration completion position (before the abutment of the sandwich member 433 against the rotation stopping member 46) that is rearward of the most forward position. However, the controller 20 can control the motor 21 such that the rotational speed of the motor 21 becomes the second rotational speed when the pin holding portion 165 reaches the most forward position after the pin holding portion 165 is detected by the first sensor 81 to have reached the first detection position. That is, the controller 20 can continuously decelerate the motor 21 during the movement of the pin holding portion 165 from the first detection position to the most forward position. The control during the movement of the pin holding portion 165 of the second embodiment from the second detection position to the last forward position is also the same.

[0134] Hereinafter, other modifications will be described.

[0135] The fastening tool 1 can be configured to fasten the work material W using a fastener of a type different from the fastener 9 exemplified in the above-described embodiment (for example, a blind rivet, a fastener of a shaft maintaining type among fasteners of a multi-piece sleeve type). The fastening tool 1 can be able to correspond to a plurality of types of fasteners by replacement of the anvil 161 and the pin holding portion 165. The shapes of the tool body 10, the head portion 16 (the anvil 161, the pin holding portion 165, and the like), the handle 17, the constituent elements, and the linking schemes thereof can be arbitrarily changed.

[0136] The motor 21 can be a motor other than a three-phase brushless DC motor (for example, a DC motor with a brush, an alternating-current motor). The fastening tool 1 can be configured to operate by power supplied from an external alternating-current power source, rather than by the battery 145.

[0137] The drive mechanism 3 can arbitrarily change its constituent elements and arrangement, as long as it can be driven by the power of the motor 21 to move the pin gripping portion 165 relative to the anvil 161 in the front-rear direction. For example, a screw feed mechanism having a nut and a screw shaft directly screwed to each other can be employed instead of the ball screw mechanism 4. The power can be transmitted from the motor 21 to the ball screw mechanism 4 through a gear set different from the example of the above-described embodiment.

[0138] The controller 20 that controls the drive of the motor 21 can not be a microcomputer, but can employ a programmable logic device such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like. In addition, the above-described control processing can be distributed and processed by a plurality of processors / processing circuits.

[0139] Furthermore, the present application is constructed in view of the gist of the above-described embodiment and its modified example, and the following aspects. At least one of the following aspects can be adopted in combination with at least one of the above-described embodiment and its modified example, and the structure (feature) described in each of the technical aspects. [Aspect 1] The control device is configured to reduce the rotational speed of the motor to a predetermined speed in response to detection by the third detection device that the pin gripping portion reaches the second detection position, and thereafter drive the motor at the predetermined speed until the third abutting portion and the fourth abutting portion abut as detected by the second detection device. [Aspect 2] The third detection device is a magnetic sensor. [Aspect 3] The rotational speed before the deceleration is the highest rotational speed of the motor, The rotational speed after the deceleration is 15% or less of the rotational speed before the deceleration. [Aspect 4] The reaction force receiving portion includes (i) a receiving member disposed behind the nut member and supported to the tool body in a manner capable of moving 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 applying a force to the receiving member in the front direction relative to the tool body, The receiving member (i) is always disposed at the first position under the force of the elastic member, and (ii) is configured to move to the second position in the rear direction with respect to the tool body in response to a reaction force in the rear direction acting on the nut member, The second abutting portion is a rear end portion of the receiving member that abuts against the first abutting portion when the receiving member is at the second position. The sandwiching member 433 is an example of the "receiving member" of the present embodiment, and the elastic member 437 is an example of the "elastic member".

Claims

1. A fastening tool configured to fasten work materials using a fastener comprising a pin and a cylindrical portion, characterized in that, It comprises a tool body, a motor, a pin holding part, a first detection device, a first abutting part, a second abutting part, a second detection device, and a control device, wherein, The motor is housed within the tool body; The pin holding part is configured to hold the pin. The pin holding part is connected to the motor in an actuating manner. With the power of the motor, it can move relative to the tool body between the foremost position and the rearmost position along the drive axis that defines the front-rear direction of the fastening tool. The first detection device is configured to detect the first detection position of the pin holding part in the front-rear direction, which is located between the foremost position and the rearmost position. The first abutting part is configured to move integrally with the pin holding part relative to the tool body in the front-rear direction; The second abutting part is disposed within the tool body and is configured to abut against the first abutting part in response to the pin holding part moving from the rear to the foremost position, thereby positioning the pin holding part at the foremost position. The second detection device is configured to detect the contact between the first abutting part and the second abutting part; The control device is configured to control the drive of the motor. The pin holding part is configured to secure the work material by the fastener by moving from the foremost position to the rear. The control device is configured to decelerate the motor in response to the first detection device detecting that the pin holding part has reached the first detection position during the forward movement of the pin holding part, and then stop the motor in response to the second detection device detecting that the first abutting part and the second abutting part are abutting.

2. The fastening tool according to claim 1, characterized in that, The control device is configured to reduce the rotational speed of the motor to a predetermined speed in response to the first detection device detecting that the pin holding part has reached the first detection position, and then drive the motor at the predetermined speed before the second detection device detects that the first abutting part abuts against the second abutting part.

3. The fastening tool according to claim 1 or 2, characterized in that, The second detection device is configured to detect physical quantities related to the driving state of the motor.

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

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

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

7. The fastening tool according to any one of claims 1 to 5, characterized in that, The control device is configured to decelerate the motor by changing the duty cycle used for PWM control of the motor.

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

9. The fastening tool according to claim 8, characterized in that, The decelerated rotational speed is set such that the stress at which the first abutting part and the second abutting part meet does not exceed the fatigue limit of the first abutting part and the second abutting part.

10. The fastening tool according to any one of claims 1 to 9, characterized in that, It also has a lead screw feed mechanism that is actuated and connected to the motor and the pin holding part. The lead screw feed mechanism includes: (i) A nut component, which is supported within the tool body in a manner that allows it to rotate about the drive axis, and is configured to be rotated by the power of the motor; (ii) A shaft component that engages with the nut component in an actuating manner, moving linearly along the front-rear direction integrally with the pin holding portion according to the rotation of the nut component. The shaft component has an anti-rotation part configured to prevent rotation about the drive axis by engaging with the tool body. A portion of the anti-rotation part constitutes the first abutment part.

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

12. The fastening tool according to any one of claims 1 to 11, characterized in that, It also includes a third detection device, a third contact part, and a fourth contact part, wherein, The third detection device is configured to detect when the pin holding part is located at a second detection position between the first detection position and the rearmost position in the front-rear direction; The third abutting part is configured to move integrally with the pin holding part relative to the tool body in the front-rear direction; The fourth abutment is disposed within the tool body and configured to abut against the third abutment in response to the pin holding portion moving from the front to the rearmost position, thereby positioning the pin holding portion at the rearmost position. The second detection device is further configured to detect the contact between the third abutment and the fourth abutment. The control device is configured such that, during the rearward movement of the pin holding part, in response to the third detection device detecting that the pin holding part has reached the second detection position, the motor decelerates, and then, in response to the second detection device detecting the contact between the third abutting part and the fourth abutting part, the rotation of the motor stops.

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