Fastening tool

Abstract

The invention provides a fastening tool. The fastening tool includes a motor including a motor shaft, a housing, a pin gripping portion, a drive mechanism connected to the pin gripping portion and configured to be capable of moving rearward and forward, a position acquisition portion configured to be capable of acquiring a relative position of the drive mechanism, and a motor control portion configured to be capable of switching a moving direction and a moving speed of the drive mechanism. The motor control unit starts forward movement of the drive mechanism so that the movement speed becomes a first speed, and decelerates the movement speed to a second speed slower than the first speed by means of PWM control that changes the duty ratio output to the motor when the acquired relative position reaches a deceleration position rearward of the initial position during forward movement. When the acquired relative position reaches a predetermined braking position forward of the deceleration position and rearward of the initial position, the driving of the motor is stopped. Therefore, the moving speed of the driving mechanism can be switched with high precision.

Description

TECHNICAL FIELD

[0001] The present application relates to a fastening tool. BACKGROUND

[0002] A fastening tool is known that fastens a work material via a fastener by pulling a pin included in the fastener. In this fastening tool, a drive mechanism to which a pin gripping portion is linked is moved rearward from an initial position by power of a motor, thereby pulling the pin rearward along a drive axis. The drive mechanism moved rearward is moved from the rearward to the initial position by power of the motor. For example, a fastening tool is disclosed in Japanese Patent Application Publication No. 2019-000892 in which the motor is braked to stop the drive mechanism when the drive mechanism moved to the initial position enters a detection range of a sensor disposed at the initial position. SUMMARY

[0003] In the related art, the stop position of the drive mechanism at the initial position sometimes deviates. When the stop position of the drive mechanism deviates, the pin gripping portion can not properly grip the pin.

[0004] The present application can be implemented as follows.

[0005] According to a first aspect of the present application, there is provided a fastening tool that fastens a work material via a fastener having a pin and a cylindrical portion. The fastening tool has a motor, a housing, a pin gripping portion, a drive mechanism, a position acquisition portion, and a motor control portion, wherein the motor includes a motor shaft; the housing houses the motor; the pin gripping portion is configured to grip the pin; the drive mechanism is linked to the pin gripping portion, and the drive mechanism is configured to be able to perform rearward movement and forward movement, the rearward movement being movement from an initial position rearward along a drive axis in a front-rear direction of the fastening tool by forward rotation of the motor shaft, and the forward movement being movement from the rearward to the initial position along the drive axis by reverse rotation of the motor shaft; the position acquisition portion is configured to be able to acquire a relative position of the drive mechanism with respect to the housing in the front-rear direction; and the motor control portion performs drive control of the motor, and is configured to be able to switch a moving direction and a moving speed of the drive mechanism. The motor control portion starts the forward movement of the drive mechanism with the moving speed being a first speed, and in the forward movement, in a case where the acquired relative position reaches a deceleration position that is rearward of the initial position, the moving speed is decelerated to a second speed that is slower than the first speed by PWM control in which a duty ratio output to the motor is changed, and in a case where the acquired relative position reaches a predetermined brake position that is forward of the deceleration position and rearward of the initial position, drive of the motor is stopped.

[0006] According to the fastening tool of the above-described aspect, since the movement speed of the drive mechanism is reduced and then the drive of the motor is stopped, the deviation of the stop position at the time when the drive mechanism is stopped while moving forward can be suppressed or prevented. By the PWM control, the rotation speed of the motor shaft can be switched with high precision, and the movement speed of the drive mechanism can be switched with high precision. Therefore, the pin gripping portion can be suppressed or prevented from failing to properly grip the pin.

[0007] According to the fastening tool of the above-described aspect, since the movement speed of the drive mechanism is reduced and then the drive of the motor is stopped, the deviation of the stop position at the time when the drive mechanism is stopped while moving forward can be suppressed or prevented. By the PWM control, the rotation speed of the motor shaft can be switched with high precision, and the movement speed of the drive mechanism can be switched with high precision. Therefore, the pin gripping portion can be suppressed or prevented from failing to properly grip the pin.

[0008] According to the fastening tool of the above-described aspect, since the movement speed of the drive mechanism is reduced and then the drive of the motor is stopped, the deviation of the stop position at the time when the drive mechanism is stopped while moving forward can be suppressed or prevented. By the PWM control, the rotation speed of the motor shaft can be switched with high precision, and the movement speed of the drive mechanism can be switched with high precision. Therefore, the pin gripping portion can be suppressed or prevented from failing to properly grip the pin.

[0009] According to a third aspect of the present application, there is provided a fastening tool that fastens a work material via a fastener having a pin and a cylindrical portion. The fastening tool has a motor, a housing, a pin holding portion, a driving mechanism, a position acquisition portion, and a motor control portion, wherein the motor includes a motor shaft; the housing houses the motor; the pin holding portion is configured to hold the pin; the driving mechanism is linked to the pin holding portion, and is configured to be capable of performing a rearward movement and a forward movement, the rearward movement being a movement from an initial position to a rearward direction along a driving axis in a front-rear direction of the fastening tool by forward rotation of the motor shaft, and the forward movement being a movement from the rearward direction to the initial position along the driving axis by reverse rotation of the motor shaft; the position acquisition portion is configured to be capable of acquiring a relative position of the driving mechanism with respect to the housing in the front-rear direction; and the motor control portion performs driving control of the motor, and is configured to be capable of switching a moving direction and a moving speed of the driving mechanism. The motor control portion starts the forward movement of the driving mechanism with the moving speed being a first speed, and in the forward movement, in a case where the moving speed reaches the first speed, determines a negative acceleration with the moving speed at a predetermined distance rearward from the initial position being a second speed slower than the first speed, decelerates the moving speed with the determined acceleration, and in a case where the acquired relative position reaches a braking position, stops the driving of the motor.

[0010] According to the fastening tool of the above aspect, since the moving speed of the driving mechanism is decelerated and the driving of the motor is stopped, it is possible to suppress or prevent a deviation in a stop position when the driving mechanism stops during the forward movement of the driving mechanism. Therefore, it is possible to suppress or prevent the pin holding portion from failing to properly hold the pin. The present application can also be realized in various ways other than the fastening tool. For example, the present application can be realized as a control method of the fastening tool, a computer program that realizes the control method, a non-transitory recording medium that records the computer program, and the like. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is an explanatory diagram that shows an example of a breakable fastener that can be used in the fastening tool according to the present application. Figure 2 is a longitudinal sectional view of the fastening tool when the screw shaft is disposed at the initial position. Figure 3 is an explanatory diagram that shows a rear side portion of the fastening tool in an enlarged manner. Figure 4 is a transverse sectional view of the rear side portion of the fastening tool. Figure 5 is an explanatory diagram that shows a front side portion of the fastening tool in an enlarged manner. Figure 6 is a block diagram showing the electric structure of the tightening tool. Figure 7 is a block diagram showing the internal functional structure of the controller. Figure 8 is an explanatory diagram showing the relationship between the position of the screw shaft and the first sensor and the second sensor. Figure 9 is a flowchart showing the drive control processing of the motor when the screw shaft is moved rearward. Figure 10 is a flowchart showing the drive control processing of the motor when the screw shaft is moved forward. Figure 11 is a timing chart showing the actions of each part in one cycle of the tightening process. Figure 12 is a flowchart showing the drive control processing of the motor according to the second embodiment. Figure 13 is a timing chart of the tightening process performed by the tightening tool according to the second embodiment. [Legend] 1: tightening tool; 2: motor; 3: transmission mechanism; 4: drive mechanism; 7: recovery container; 9: fastener; 10: housing; 11: outer housing; 13: inner housing; 15: handle; 16: head portion; 20: motor main body portion; 21: stator; 23: rotor; 25: motor shaft; 27: fan; 30: reducer housing; 31: planetary reducer; 33: intermediate shaft; 35: nut driving gear; 40: ball screw mechanism; 41: nut; 46: screw shaft; 47: extension shaft; 48: position detection mechanism; 49: link member; 70: passage; 91: pin; 95: sleeve; 111: roller guide; 113: container link portion; 114: opening portion; 117: guide sleeve; 150: circuit board; 151: trigger; 152: switch; 155: controller housing portion; 156: controller; 157: operation portion; 158: battery mounting portion; 159: battery; 161: anvil; 165: pin holding portion; 201: three-phase inverter; 203: Hall sensor; 205: current detection amplifier; 311: sun gear; 313: gear carrier; 411: driven gear; 412: radial bearing; 460: drive shaft; 461: through-hole; 463: roller holding portion; 464: roller; 481: first sensor; 482: second sensor; 485: magnet holding portion; 486: magnet; 560: CPU; 562: motor control portion; 564: shaft position acquisition portion; 565: internal bus; 566: memory; 568: interface circuit; 911: shaft portion; 913: small diameter portion; Al: drive axis; A2: rotation axis; OD: external device; Wl, W2: work material. DETAILED DESCRIPTION

[0012] Hereinafter, representative and non-limiting embodiments of the present application will be explained in detail with reference to the accompanying drawings. This detailed description is merely indicative of the preferred embodiments for practicing this application by persons of ordinary skill in the art, and is not intended to limit the scope of the present application. In addition, in order to provide further improved devices, methods of manufacturing the same, and methods of using the same, additional technical features and technical solutions disclosed in the following can be used alone or together with other technical features or technical solutions.

[0013] In addition, the combination of technical features or processes disclosed in the following detailed description is not essential in practicing the present application in the broadest sense, but is merely noted for specifically describing the representative embodiments of the present application. Also, in providing additional and useful embodiments of the present application, it is not necessary to combine various technical features and technical solutions noted in the above and below representative embodiments of various technical features and technical solutions in the order as recited herein.

[0014] All technical features recited in the specification and / or technical solutions are disclosed as separate and independent from each other as a limitation on the disclosure of the original application and the specific matters of the technical solutions. Also, as a limitation on the disclosure of the original application and the specific matters of the technical solutions, the recitation of all numerical ranges and groups or sets indicates the disclosure of intermediate structures.

[0015] In a non-limiting embodiment of the present application, the position acquisition unit can acquire the cumulative rotation speed of the motor shaft, and acquire the relative position using the acquired cumulative rotation speed of the motor shaft. According to this embodiment, the position of the driving mechanism can be acquired by a simple method.

[0016] In addition to or instead of the above embodiment, the position acquisition unit can determine that the driving mechanism reaches the deceleration position when the cumulative rotation speed acquired while moving forward reaches a predetermined cumulative rotation speed. According to this embodiment, the detection unit for detecting the detection object of the driving mechanism disposed at the deceleration position can be omitted, and the increase in the number of parts of the fastening tool can be suppressed. In addition, the position of the deceleration position can be easily set and changed compared to the case where the detection unit is provided.

[0017] In addition to or instead of the above-described embodiment, the cumulative rotation number of the motor shaft from the position at which the forward movement is started to the deceleration position can be configured to be less than the cumulative rotation number of the motor shaft from the position at which counting of the cumulative rotation number of the motor shaft is started to the position at which the forward movement is started by a predetermined cumulative rotation number. According to this embodiment, the cumulative rotation number of the motor shaft can be used to set the deceleration position rearward of the position at which counting of the cumulative rotation number of the motor shaft is started.

[0018] In addition to or instead of the above-described embodiment, the position acquisition unit can acquire the cumulative rotation number of the motor shaft. The shaft position acquisition unit can acquire the arrival position at which the movement speed reaches the first speed using the acquired cumulative rotation number of the motor shaft. The shaft position acquisition unit can calculate the distance from the acquired arrival position to the braking position. The motor control unit can calculate the acceleration using the calculated distance from the arrival position to the braking position, and decelerate the movement speed at the calculated acceleration. According to this embodiment, the movement speed at the braking position can be decelerated to the target speed even in the case where the arrival position varies. Therefore, the stop position of the drive mechanism can be suppressed or prevented from deviating due to variation in the arrival position.

[0019] In addition to or instead of the above-described embodiment, the motor control unit can decelerate the movement speed at a certain negative acceleration corresponding to the acquired distance from the arrival position to the braking position. According to this embodiment, the calculation cost of the acceleration can be suppressed.

[0020] In addition to or instead of the above-described embodiment, the position acquisition unit can start acquisition of the cumulative rotation number of the motor shaft at the time when the detection result of the braking position detection unit switches from a detected state in which the detection object is detected to a non-detected state in which the detection object is not detected in the backward movement. According to this embodiment, the structure in which acquisition of the cumulative rotation number of the motor shaft is started at the time when the drive mechanism starts to move can improve the estimation accuracy of the position of the drive mechanism.

[0021] In addition to or instead of the above-described embodiment, the motor control section can switch the movement speed by PWM control that changes a duty ratio output to the motor. According to this embodiment, the rotation speed of the motor shaft can be switched with high precision by PWM control, and the movement speed of the drive mechanism can be switched with high precision.

[0022] In addition to or instead of the above-described embodiment, the motor control section can perform constant rotation speed control that adjusts a drive voltage of the motor in such a manner that a rotation speed per unit time of the motor shaft becomes a predetermined target rotation speed. The motor control section can switch the movement speed by switching of the target rotation speed. According to this embodiment, the movement speed of the drive mechanism can be switched with high precision by constant rotation speed control.

[0023] In addition to or instead of the above-described embodiment, the motor control section can stop the motor by a short-circuit brake that short-circuits terminals of the motor. According to this embodiment, the time required to stop the motor can be shortened. In addition, the braking distance of the drive mechanism can be shortened, and the deviation of the stop position of the drive mechanism can be suppressed.

[0024] In addition to or instead of the above-described embodiment, the drive mechanism can include a nut that is rotationally driven around the drive axis by power of the motor, and a shaft that is linked to the pin holding section and configured to perform the rearward movement by forward rotation of the motor shaft and perform the forward movement by reverse rotation of the motor shaft. According to this embodiment, the movement direction and the movement speed of the drive mechanism can be switched with high precision by a so-called lead screw mechanism.

[0025] In addition to or instead of the above-described embodiment, there can be a detection object and a rearward braking position detection section. The detection object is provided to the drive mechanism and moves integrally with the drive mechanism. The rearward braking position detection section is configured to be able to detect the detection object provided to the drive mechanism in a state where the drive mechanism is disposed at a rearward braking position that is rearward of the braking position. The motor control section can stop the drive of the motor when the detection object is detected by the rearward braking position detection section. According to this embodiment, the drive mechanism at the rearward detection position can be detected by a simpler method than a method that estimates the position of the drive mechanism using a cumulative rotation speed of the motor.

[0026] In addition to or instead of the above-described embodiment, there can be a trigger that can accept a pressing operation and a release operation that releases the pressing operation. The motor control section can drive the motor to rotate the motor shaft in the forward direction when the trigger accepts the pressing operation, and can drive the motor to rotate the motor shaft in the reverse direction when the trigger accepts the release operation. According to this embodiment, the user can switch the forward movement and the rearward movement of the driving mechanism by a simple method of operating the trigger.

[0027] A. First Embodiment: A1. Structure of fastener: An example of a fastener that can be used in the fastening tool 1 related to the first embodiment is shown in Figure 1 Fig. 1. The fastener 9 has a pin 91 and a sleeve 95. The fastener 9 is of a breakage type in which a portion of the shaft portion 911 of the pin 91, also referred to as a pin tail or mandrel, is broken and pulled off. The sleeve 95 has a substantially cylindrical shape and is configured so as to be capable of being inserted into the shaft portion 911. The sleeve 95 is an example of a "barrel portion".

[0028] A2. Appearance structure of fastening tool 1: Referring to Figure 2 , a fastening tool 1 that can fasten a work material using the fastener 9 is described. As shown in Figure 2 , the outer contour of the fastening tool 1 is formed by an outer housing 11, a handle 15, and a head portion 16. The outer housing 11 is a substantially rectangular box body that extends along a prescribed driving axis Al. As shown in Figure 2 , a motor 2, a driving mechanism 4, and a transmission mechanism 3 are housed in the outer housing 11. An inner housing 13 is fixed within the outer housing 11. A housing 10 that is formed integrally by the outer housing 11 and the inner housing 13.

[0029] The head portion 16 is disposed so as to extend along the driving axis Al. The head portion 16 includes a cylindrical anvil 161 and a pin holding portion 165 disposed within the anvil 161. The anvil 161 is joined to one end portion in the longitudinal direction of the outer housing 11. A recovery container 7 that can accommodate the shaft portion 911 separated from the fastener 9 in a fastening process is detachably installed at the other end portion of the outer housing 11.

[0030] The handle 15 is configured so as to be capable of being held by a user. The handle 15 protrudes from substantially the center in the longitudinal direction of the outer housing 11 in a direction that intersects the driving axis Al (in this embodiment, a direction that is substantially orthogonal to the driving axis Al).

[0031] In this specification, regarding the orientation of the fastening tool 1, the extension direction of the drive axis A1 (also referred to as the "major axis direction of the housing 11") is defined as the front-rear direction of the fastening tool 1. The side with the organic head 16 disposed in the front-rear direction is defined as the front side, and the side with the recovery container 7 disposed in the rear side is defined as the rear side. The direction orthogonal to the drive axis A1 and corresponding to the extension direction of the handle 15 is defined as the up-down direction. The side with the housing 11 disposed in the up-down direction is defined as the upper side, and the side with the protruding end (free end) of the handle 15 is defined as the lower side. Furthermore, the direction orthogonal to both the front-rear and up-down directions is defined as the left-right direction.

[0032] The upper end of the handle 15 functions as a base end connected to the housing 11. A trigger 151 is provided at the upper end of the handle 15, configured to accept a pressing operation (pulling operation) and a releasing operation (releasing the pressing operation) from the user. A battery mounting section 158 is provided at the lower end of the handle 15, configured to allow for the removal and installation of a battery 159. The battery 159 is a rechargeable power source, such as a known battery pack or rechargeable battery containing multiple cells, like a lithium-ion battery. The battery 159 supplies power to various parts of the fastening tool 1 and the motor 2.

[0033] The fastening tool 1 is configured to fasten the working materials W1 and W2 via the fastener 9. A portion of the shaft portion 911 of the fastener 9 is inserted into the top end of the head 16 of the fastening tool 1, and is held by the pin holding portion 165 described later when the fastener 9 is engaged with the top end of the anvil 161.

[0034] A3. Internal structure of fastening tool 1: use Figures 3 to 5 The internal structure of the fastening tool 1 will be explained below. The housing 10 houses a motor 2, a drive mechanism 4 driven by the power of the motor 2, and a transmission mechanism 3 that transmits the power of the motor 2 to the drive mechanism 4.

[0035] Motor 2 is, for example, a brushless DC motor. Figure 3 As shown, the motor 2 is housed in the lower part of the rear end portion of the housing 11. In this embodiment, the entire motor 2 is positioned below the drive axis A1. The motor 2 includes a motor body 20 and a motor shaft 25. The motor body 20 includes a stator 21 and a rotor 23. The motor shaft 25 extends from the rotor 23 and is configured to rotate integrally with the rotor 23. The rotation axis A2 of the motor shaft 25 is configured to be located below and parallel to the drive axis A1. The rotation axis A2 extends in the front-rear direction. The front end of the motor shaft 25 protrudes into the reducer housing 30. A fan 27 for cooling the motor 2 is fixed to the rear end of the motor shaft 25.

[0036] like Figure 3As shown, the transmission mechanism 3 includes a planetary reducer 31, an intermediate shaft 33, and a nut drive gear 35. The planetary reducer 31 is positioned in front of the motor 2. Rotational power from the motor shaft 25 is transmitted to the planetary reducer 31. The planetary reducer 31 increases the torque of the motor 2 and transmits it to the intermediate shaft 33 along the power transmission path from the motor 2 to the ball screw mechanism 40 of the drive mechanism 4.

[0037] The planetary reducer 31 has two sets of planetary gear mechanisms and a resin reducer housing 30. The reducer housing 30 is positioned in front of the motor 2 and fixed to the outer casing 11. The reducer housing 30 houses the two sets of planetary gear mechanisms. A sun gear 311 is fixed to the front end of the motor shaft 25. The sun gear 311 is the upstream planetary gear mechanism of the planetary reducer 31. The gear carrier 313 is the downstream planetary gear mechanism of the planetary reducer 31. The gear carrier 313 is the final output shaft of the planetary reducer 31.

[0038] The intermediate shaft 33 is configured to rotate coaxially with the motor shaft 25. The rear end of the intermediate shaft 33 is connected to the gear carrier 313. As a result, the intermediate shaft 33 and the gear carrier 313 rotate integrally. The nut drive gear 35 is fixed to the outer periphery of the front end of the intermediate shaft 33. The nut drive gear 35 meshes with the driven gear 411 formed on the outer periphery of the nut 41 (described later), transmitting the rotational power of the intermediate shaft 33 to the nut 41. The nut drive gear 35 and the driven gear 411 constitute a reduction gear mechanism.

[0039] like Figure 3 As shown, the drive mechanism 4 and the pin holding part 165 (described later) Figure 5 The drive mechanism 4 moves along the drive axis A1 in the front-to-back direction via the power of the motor 2, causing the pin holding part 165 to move in the front-to-back direction. In this embodiment, the drive mechanism 4 is composed of a ball screw mechanism 40 housed in the upper part of the outer casing 11. Figure 3 and Figure 4 As shown, the ball screw mechanism 40 includes a nut 41 and a screw shaft 46. The ball screw mechanism 40 converts the rotational motion of the nut 41 into the linear motion of the screw shaft 46, so as to make the pin holding part 165 move in a linear manner.

[0040] Nut 41 is a cylindrical component. Nut 41 is supported on the inner housing 13 in a state where its movement in the rear-to-rear direction is restricted and it is rotatable about the drive axis A1. A driven gear 411 is formed on the outer periphery of nut 41. Nut 41 is supported on the inner housing 13 via a pair of radial bearings 412, 413 disposed on the front and rear sides of the driven gear 411, allowing it to rotate about the drive axis A1. The driven gear 411 meshes with a nut drive gear 35. The driven gear 411 receives rotational power from the motor 2 via the nut drive gear 35, thereby causing nut 41 to rotate about the drive axis A1.

[0041] The lead screw shaft 46 is a generally elongated cylindrical component extending along the drive axis A1. The lead screw shaft 46 is an example of a "shaft". The lead screw shaft 46 is inserted into the nut 41. The lead screw shaft 46 is engaged with the nut 41 in a state where it can move in the back-and-forth direction along the drive axis A1. A helical track is formed between the lead screw shaft 46 and the nut 41. The helical track is defined between a helical groove formed on the inner circumferential surface of the nut 41 and a helical groove formed on the outer circumferential surface of the lead screw shaft 46. A plurality of balls (not shown) are arranged in a rolling manner on the helical track. The lead screw shaft 46 is engaged with the nut 41 via the plurality of balls. Driven by the rotation of the nut 41, the lead screw shaft 46 moves linearly in the back-and-forth direction along the drive axis A1.

[0042] like Figure 4 As shown, a roller holding portion 463 is fixed to the central portion of the rear end of the lead screw shaft 46. The roller holding portion 463 has an arm portion. The arm portion is a component that is orthogonal to the lead screw shaft 46 and protrudes to the left and right directions from the central portion of the roller holding portion 463. Rollers 464 are held rotatably at each end of the arm portion. On the other hand, roller guides 111 corresponding to a pair of left and right rollers 464 are provided on the left and right inner walls of the outer casing 11. The roller guides 111 restrict the upward and downward movement of the rollers 464. The rollers 464 disposed in the roller guides 111 roll along the roller guides 111 in the front-back direction. By the rollers 464 abutting against the roller guides 111, the rotation of the lead screw shaft 46 around the drive axis A1 is restricted as the nut 41 rotates.

[0043] like Figure 3 As shown, a magnet holding part 485 is fixed to the upper side of the rear end of the lead screw shaft 46. A magnet 486 is mounted on the upper end of the magnet holding part 485. The magnet 486 is an example of a "detection object". The magnet 486 is integral with the lead screw shaft 46 and moves integrally in the front-back direction as the lead screw shaft 46 moves in the front-back direction.

[0044] A position detection mechanism 48 capable of detecting the magnet 486 is provided on the housing 11. The position detection mechanism 48 includes a first sensor 481 and a second sensor 482. The second sensor 482 is positioned rearward of the first sensor 481. The first sensor 481 and the second sensor 482 are, for example, magnetic field detection sensors; in this embodiment, they are Hall sensors with Hall elements. The first sensor 481 is an example of a "brake position detection unit," and the second sensor 482 is an example of a "rear brake position detection unit." The first sensor 481 and the second sensor 482 are connected to the controller 156 (see reference 156) via wires not shown. Figure 6 Electrical connection. When the first sensor 481 and the second sensor 482 detect the magnet 486 disposed within the detection range, they output a predetermined detection signal to the controller 156. In this embodiment, the detection results of the first sensor 481 and the second sensor 482 are used for the drive control of the motor 2 of the controller 156.

[0045] like Figure 3 and Figure 4 As shown, an extension shaft 47 is connected and fixed to the rear end of the lead screw shaft 46 in a coaxial manner. The extension shaft 47 is integral with the lead screw shaft 46. Hereinafter, the integrally formed lead screw shaft 46 and extension shaft 47 will be collectively referred to as "drive shaft 460". A through hole 461 is provided on the drive shaft 460, extending through the drive shaft 460 along the drive axis A1. Furthermore, the outer diameter of the through hole 461 is set to be slightly larger than the maximum diameter of the shaft portion 911 of the fastener 9 that can be used in the fastening tool 1.

[0046] An opening 114 is formed on the drive axis A1 at the rear end of the housing 11, connecting the interior and exterior of the housing 11. A cylindrical guide sleeve 117 is fixed to the front side of the opening 114. The inner diameter of the guide sleeve 117 is approximately equal to the outer diameter of the extension shaft 47. The rear end of the extension shaft 47 is positioned on the lead screw shaft 46. Figure 3 and Figure 4 The initial position is configured within the guide sleeve 117. As the screw shaft 46 moves rearward from the initial position with the rotation of the nut 41, the extension shaft 47 moves rearward within the guide sleeve 117.

[0047] like Figure 3 and Figure 4 As shown, a container connecting part 113 is provided at the rear end of the outer casing 11. The container connecting part 113 is configured to be detachable and reassembled as a recycling container 7 for recovering the broken shaft 911. The user can install the recycling container 7 onto the outer casing 11 by communicating the opening 114 with the internal space of the recycling container 7 through the container connecting part 113.

[0048] like Figure 5As shown, the machine head 16 has: a cylindrical anvil 161 configured to abut against the sleeve 95 of the fastener 9; and a pin holding portion 165 configured to hold the shaft portion 911 of the fastener 9. The anvil 161 is detachably connected to the front end of the housing 10 via a predetermined connecting member. The pin holding portion 165 is coaxially held within the anvil 161 in a manner that allows it to move relative to the anvil 161 along the drive axis A1.

[0049] The pin holding part 165 is integrally connected to the lead screw shaft 46 via the connecting member 49. Thus, a channel 70 extending along the drive axis A1 is formed from the top of the pin holding part 165 to the opening 114 of the housing 11. The shaft part 911, after being separated from the fastener 9, passes through the channel 70 and is received in the recycling container 7.

[0050] like Figure 2 As shown, a trigger 151 is provided on the front side of the upper end of the handle 15. Inside the handle 15 on the rear side of the trigger 151, a switch 152 is housed that can switch between an on and off state in response to pressing the trigger 151.

[0051] The lower end of the handle 15 is formed into a rectangular box shape, constituting a controller housing 155. A circuit board 150 is housed inside the controller housing 155. As described later, the circuit board 150 is equipped with a controller 156 for controlling the movement of the fastening tool 1, a 3-phase inverter 201, a current sensing amplifier 205, and the like. An operation section 157 is provided at the upper part of the controller housing 155, capable of inputting various information based on external user input.

[0052] When the trigger 151 is pressed, the drive motor 2 drives the drive mechanism 4. When the pin holding portion 165 of the shaft portion 911 holding the fastener 9 moves rearward relative to the anvil 161 along the drive axis A1, the pin 91 is pulled rearward relative to the sleeve 95. In use... Figure 1 In the case of the fastener 9 with the fracture type shown, the sleeve 95 deforms and presses against the shaft portion 911 of the pin 91. After the working materials W1 and W2 are clamped by the head 915 of the pin 91 and the sleeve 95, the shaft portion 911 breaks and separates at the small diameter portion 913, and the fastening of the working materials W1 and W2 ends.

[0053] Thus, the fastening tool 1 of this embodiment is configured such that the action of moving the pin holding part 165 from the front initial position to the rear stop position and then returning to the initial position by the drive mechanism 4 is performed as a cycle, and the fastening process of fastening the work material using the fastener 9 is performed.

[0054] A4. Electrical structure of fastening tool 1: like Figure 6As shown, the fastening tool 1 includes a three-phase inverter 201, a Hall sensor 203, and a controller 156. The three-phase inverter 201 has a three-phase bridge circuit using six semiconductor switching elements. The three-phase inverter 201 switches each of the switching elements in the three-phase bridge circuit according to the duty cycle indicated by the control signal from the controller 156. As a result, a drive pulse corresponding to this duty cycle is supplied to the motor 2. The Hall sensor 203 has three Hall elements arranged corresponding to each of the motor 2. The Hall sensor 203 outputs a signal indicating the rotation angle of the rotor 23 to the controller 156.

[0055] The current sensing amplifier 205 is electrically connected to the controller 156. The current sensing amplifier 205 converts the drive current of the motor 2 into voltage through a shunt resistor, and outputs the amplified signal to the controller 156.

[0056] like Figure 7 As shown, the controller 156 comprises a CPU 560 as a processor, a memory 566 including ROM or RAM, an interface circuit 568, and a computer having a timer (not shown). These are connected via an internal bus 565 in a manner enabling bidirectional communication. A device including a timer is connected to the interface circuit 568. Figure 6 The external devices OD of the switch 152, operation unit 157, first sensor 481, second sensor 482, and three-phase inverter 201 are shown.

[0057] The memory 566 stores programs for performing the various functions implemented by the fastening tool 1 according to this embodiment. For example... Figure 7 As shown, the CPU 560 reads and executes the program stored in the memory 566, and the controller 156 functions as both the motor control unit 562 and the shaft position acquisition unit 564. The shaft position acquisition unit 564 is an example of a "position acquisition unit".

[0058] The motor control unit 562 controls the drive of the motor 2 based on the signal output from the external device OD. In this embodiment, the motor control unit 562 can switch the direction and speed of movement of the lead screw shaft 46 by controlling the drive of the motor 2. For example, the motor control unit 562 controls the power supply to the motor 2 via the three-phase inverter 201 based on the signal input from the Hall sensor 203. As a result, the rotational speed of the motor 2 is controlled, and the movement speed of the lead screw shaft 46 is switched. Furthermore, in this embodiment, the rotational speed is controlled using PWM control.

[0059] The motor control section 562 is capable of switching the rotation direction of the rotor 23 of the motor 2, that is, the rotation direction of the motor shaft 25, to forward rotation and reverse rotation. The "forward rotation" refers to the rotation direction in which the lead screw shaft 46 in the drive mechanism 4 is moved rearward with respect to the housing 10, and the "reverse rotation" refers to the rotation direction in which the lead screw shaft 46 in the drive mechanism 4 is moved forward with respect to the housing 10. When the trigger 151 receives a pressing operation by the user and the switch 152 is turned on, the motor control section 562 drives the motor 2 to cause the nut 41 to rotate forward, thereby moving the lead screw shaft 46 rearward. When the trigger 151 receives a releasing operation by the user and the switch 152 is turned off, the motor control section 562 drives the motor 2 to cause the nut 41 to rotate reverse, thereby moving the lead screw shaft 46 forward. With this configuration, the user is able to switch the forward movement and the rearward movement of the lead screw shaft 46 by a simple method of operating the trigger 151.

[0060] The shaft position acquisition section 564 acquires the relative position of the drive mechanism 4 with respect to the housing 10 in the front-rear direction, based on a signal output from the external device OD. In the present embodiment, the shaft position acquisition section 564 acquires the relative position of the lead screw shaft 46 in the drive mechanism 4 (hereinafter, simply referred to as "the position of the lead screw shaft 46"). In the present embodiment, the shaft position acquisition section 564 acquires the position of the lead screw shaft 46 by the detection results of the first sensor 481 and the second sensor 482, the cumulative rotation speed (rotation angle) of the motor 2 acquired from the Hall sensor 203, the number of drive pulses supplied to the motor 2 or the drive time of the motor 2, or the like, or an operation using these information. Further, the "cumulative rotation speed of the motor 2" includes the cumulative rotation speed of the motor shaft 25 and the cumulative rotation speed of the rotor 23. The "acquisition of the position of the lead screw shaft 46" includes the estimation of the position of the lead screw shaft 46 by an operation or the like.

[0061] A5. Relationship between the position of the lead screw shaft 46 in the front-rear direction and the drive control of the motor 2: The relationship between the drive control of the motor 2 and the position of the lead screw shaft 46 in the front-rear direction performed by the tightening tool 1 of the present application will be described with reference to Figure 8 The shaft position acquisition section 564 acquires the position of the lead screw shaft 46 in the front-rear direction using the detection results of the first sensor 481 and the second sensor 482 and the cumulative rotation speed of the motor 2 acquired from the Hall sensor 203. The motor control section 562 performs the drive control of the motor 2 corresponding to the acquired position of the lead screw shaft 46 in the front-rear direction.

[0062] As Figure 8The arrow P indicates the direction of movement of the screw shaft 46 and the magnet 486 in one cycle. In the present embodiment, in one cycle of the fastening process of the fastener 9, the screw shaft 46 moves from the initial position PS in the front to the stop position PE in the rear, and then moves from the stop position PE to the initial position PS in the front. As described above, since the magnet 486 is integrated with the screw shaft 46, the positions of the screw shaft 46 and the pin gripping portion 165 correspond to the position of the magnet 486. In the following description, for convenience of explanation, in the case of indicating the position of the screw shaft 46, the same reference numeral as that indicating the position of the magnet 486 is sometimes used.

[0063] In Figure 8 The detection range Rl of the first sensor 481, the detection range R2 of the second sensor 482, and the movement range R3 of the magnet 486 are schematically shown in FIG. 1. In the case where the screw shaft 46 is disposed at the initial position PS, the magnet 486 is included in the detection range Rl of the first sensor 481. Further, for example, at the completion of one cycle of the fastening process, if the screw shaft 46 does not accurately return to the initial position PS, it is possible that the pin gripping portion 165 cannot properly grip the pin 91. Therefore, it is preferable to make the screw shaft 46 stop at the initial position PS as accurately as possible.

[0064] As Figure 8 As shown in the center of FIG. 1, when the screw shaft 46 is disposed at the initial position PS, the first sensor 481 detects the magnet 486, and outputs a detection signal to the controller 156. When the drive motor 2 is driven, the screw shaft 46 moves in the rearward direction. When the screw shaft 46 moves in the rearward direction, the magnet 486 reaches a detection-out position PD that is out of the detection range Rl. Also, the movement of the screw shaft 46 in the rearward direction is referred to as "rearward movement". At the detection-out position PD, the output of the detection signal from the first sensor 481 is switched from ON to OFF.

[0065] When the screw shaft 46 further moves in the rearward direction from the detection-out position PD, the magnet 486 reaches a rear detection position PB that enters the detection range R2 of the second sensor 482. At the rear detection position PB, the output of the detection signal from the second sensor 482 is switched from OFF to ON. The rear detection position PB is an example of a "rear stop position". The state where the outputs of the detection signals from the first sensor 481 and the second sensor 482 are ON is a state where the magnet 486 is detected, and the state where the outputs are OFF is a state where the magnet 486 is not detected. The state where the outputs of the detection signals from the first sensor 481 and the second sensor 482 are ON is referred to as a "detected state", and the state where the outputs are OFF is referred to as a "non-detected state".

[0066] When magnet 486 reaches the rear detection position PB and a detection signal is detected from the second sensor 482, the motor control unit 562 executes braking control on the motor 2. The lead screw 46 moves rearward from the start of braking until the motor 2 comes to a complete stop. When the motor 2 comes to a complete stop, magnet 486 stops at the stop position PE within the detection range R2. With the lead screw 46 positioned at the stop position PE, the second sensor 482 outputs a detection signal. By stopping the drive of the motor 2 using the detection result from the second sensor 482, the position of the lead screw 46 at the rear detection position PB can be detected using a simpler method than estimating the position of the lead screw 46 based on the cumulative rotational speed of the motor 2.

[0067] In this embodiment, the shaft position acquisition unit 564 uses the cumulative rotational speed of the motor 2 obtained from the Hall sensor 203 to estimate the position of the lead screw shaft 46. Figure 8 The upper side shows the correspondence between the rotational speed of the motor 2 and the position of the magnet 486, obtained by the shaft position acquisition unit 564. Figure 8 In the example, the cumulative rotational speed of motor 2 in forward rotation is shown. Specifically, the cumulative rotational speed of motor 2 increases as the lead screw shaft 46 moves backward and decreases as the lead screw shaft 46 moves forward.

[0068] In this embodiment, such as Figure 8 As shown in position CD on the upper side, the shaft position acquisition unit 564 moves from the lead screw shaft 46 to the detection external position PD. The output of the detection signal from the first sensor 481 is switched from on to off, and the counting of the cumulative rotational speed of the motor 2 begins. With this configuration, the influence of the initial position PS deviation on the counting of the cumulative rotational speed of the motor 2 can be suppressed. Therefore, compared to starting the counting of the cumulative rotational speed of the motor 2 from the initial position PS, the estimation accuracy of the position of the lead screw shaft 46 can be improved.

[0069] like Figure 8 As indicated by the arrow DD on the upper side, when the switch 152 is disconnected by releasing the trigger 151, the lead screw 46 moves forward toward the initial position PS. This forward movement of the lead screw 46 is also referred to as "forward movement". Furthermore, the forward movement of the lead screw 46 can begin at any position from the initial position PS to the stop position PE.

[0070] The target speed V1 for the forward movement of the lead screw 46 can be arbitrarily set. In this embodiment, the target speed V1 is the highest speed of the lead screw 46 that can be achieved by the motor 2. The target speed V1 is an example of "first speed". When the lead screw 46 moves forward from the stop position PE, the magnet 486 disengages from the detection range R2, and the output of the detection signal from the second sensor 482 is switched from on to off. When the lead screw 46 moves forward further, the magnet 486 reaches the deceleration position P1.

[0071] The deceleration position P1 is a position further back than the initial position PS. The deceleration position P1 can be preset, for example, based on prior experimental results, to improve the positional accuracy of the lead screw 46 when it stops at the initial position PS. For example, when the lead screw 46 moves forward from the stop position PE, the deceleration position P1 is set to be 1.0 mm to 5.0 mm away from the braking position P2 (described later).

[0072] In this embodiment, the deceleration position P1 is set based on the cumulative rotational speed of the motor 2. The shaft position acquisition unit 564 determines whether the magnet 486 has reached the deceleration position P1 based on the cumulative rotational speed of the motor 2. With this configuration, the detection unit for detecting the magnet 486 used to detect the deceleration position P1 can be omitted, thus suppressing the increase in the number of parts of the fastening tool 1. In addition, compared with the case where a detection unit is provided, the position of the deceleration position P1 can be easily set and changed.

[0073] like Figure 9 to 11 As shown at position C1 on the upper side, in this embodiment, the deceleration position P1 is set to the position where the cumulative speed of the motor 2 reaches a predetermined cumulative speed TH from the start of forward movement of the lead screw shaft 46. The configuration is such that the cumulative speed TH of the motor 2 is less than the cumulative speed THa of the motor 2 by a predetermined cumulative speed THb. Here, the cumulative speed TH of the motor 2 refers to the cumulative speed of the motor from the stop position PE where forward movement of the lead screw shaft 46 begins, to the deceleration position P1. The cumulative speed THa of the motor 2 refers to the cumulative speed of the motor from the detection outer position PD where the counting of the cumulative speed of the motor 2 begins, to the stop position PE, when moving backward from the lead screw shaft 46. When the lead screw shaft 46 starts moving forward from the stop position PE, the deceleration position P1 is set to a distance behind the detection outer position PD corresponding to the cumulative speed THb.

[0074] At the moment when the lead screw shaft 46 begins to move forward, the shaft position acquisition unit 564 starts counting the cumulative speed of the motor 2. When the cumulative speed of the motor 2 reaches a predetermined cumulative speed TH, the shaft position acquisition unit 564 determines that the lead screw shaft 46 has reached the deceleration position P1.

[0075] When the screw shaft 46 reaches the deceleration position PI, the motor control section 562 controls the motor 2, and the speed of the screw shaft 46 is switched to a target speed V2 that is slower than the target speed VI. In the present embodiment, the motor control section 562 reduces the rotational speed of the motor 2 per unit time in such a manner that the moving speed of the screw shaft 46 is about 50% of the target speed VI.

[0076] In order to improve the accuracy of the stop position of the screw shaft 46, it is preferable that the target speed V2 be set at a speed of 50% or more and 70% or less of the target speed VI. The target speed V2 is an example of "a second speed". In the present embodiment, the motor control section 562 reduces the rotational speed of the motor 2 per unit time by PWM control that changes the duty ratio output to the motor 2. By the PWM control, the rotational speed of the motor 2 can be switched with high accuracy, and the moving speed of the screw shaft 46 can be switched with high accuracy.

[0077] When the screw shaft 46 further moves forward from the deceleration position PI, the brake position P2 at which the output of the detection signal from the first sensor 481 is switched from off to on is reached. The brake position P2 is a position that is substantially the same as the detection outer position PD. The shaft position acquisition section 564 determines that the screw shaft 46 reaches the brake position P2 when the output of the detection signal from the first sensor 481 is switched from off to on.

[0078] When the screw shaft 46 reaches the brake position P2, the motor control section 562 brakes the motor 2, and the screw shaft 46 is braked. Even after the motor 2 is braked, the screw shaft 46 moves forward before the motor 2 is completely stopped, and stops at the initial position PS. In the present embodiment, the motor control section 562 stops the motor 2 by a short-circuit brake that shorts the terminals of the motor 2. By so configuring, the stop time of the motor 2 can be shortened. In addition, the brake distance of the screw shaft 46 can be shortened, and the deviation of the stop position of the screw shaft 46 can be suppressed. Furthermore, the short-circuit brake includes a 3-phase short-circuit brake and a 2-phase short-circuit brake.

[0079] A6. Drive control of the motor 2: The flow of the drive control of the motor 2 in one cycle of the fastening process of the fastener 9 will be described with reference to Figure 9 Figure 10 The flow illustrated is started in a state where the trigger 151 is released, in a state where the screw shaft 46 is disposed at the initial position PS. In addition, in the following description, each "step" in the process will be simply referred to as "S".

[0080] ​In S10, the motor control section 562 stands by for an operation in which the switch 152 is switched to ON by a press operation of the trigger 151. When the switch 152 is turned ON by the press operation of the trigger 151 (S10: YES), the motor control section 562 shifts the process to S20, rotates the motor 2 in the forward direction, and moves the screw shaft 46 in the rearward direction. The motor control section 562 controls, for example, so that the moving speed of the screw shaft 46 when moved in the rearward direction becomes the target speed VI.

[0081] In S30, the shaft position acquisition section 564 monitors the output of the detection signal from the first sensor 481. When the output of the detection signal from the first sensor 481 is switched from ON to OFF (S30: YES), the shaft position acquisition section 564 determines that the screw shaft 46 has reached the outer detection position PD, and shifts the process to S40. In S40, the shaft position acquisition section 564 starts counting the cumulative rotation speed of the motor 2.

[0082] In S50, the shaft position acquisition section 564 monitors the output of the detection signal from the second sensor 482. If the output of the detection signal from the second sensor 482 is OFF, the shaft position acquisition section 564 determines that the rearward detection position PB has not been reached (S50: NO), and shifts the process to S52. In S52, the motor control section 562 monitors whether the switch 152 is turned OFF by a release operation of the trigger 151. When the switch 152 is turned OFF (S52: YES), the motor control section 562 shifts the process to S60. If the switch 152 is not turned OFF within a prescribed time (S52: NO), the motor control section 562 returns the process to S50.

[0083] In S50, when the output of the detection signal from the second sensor 482 is switched from OFF to ON (S50: YES), the shaft position acquisition section 564 determines that the screw shaft 46 has reached the rearward detection position PB. In S60, the motor control section 562 performs control to brake the motor 2. When the rotation speed of the motor 2 is zero by the braking of the motor 2, the screw shaft 46 is stopped at the stop position PE. In this embodiment, the motor control section 562 brakes the motor 2 by stopping the energization of the motor 2 (making the duty ratio zero) when the screw shaft 46 is moved in the rearward direction. The motor control section 562 can also stop the motor 2 by a short-circuit brake.

[0084] Figure 11 The flowchart shown starts in a state in which the screw shaft 46 is moved in the rearward direction by a press operation of the trigger 151 or the screw shaft 46 is stopped at the stop position PE by a press operation of the trigger 151.

[0085] In S110, the motor control section 562 stands by for an operation in which the switch 152 is switched from ON to OFF by the release operation of the trigger 151. When the switch 152 is made OFF (S110: YES), the motor control section 562 shifts the process to S120, reverses the motor 2, and moves the screw shaft 46 in the front direction. The motor control section 562 controls so that the moving speed of the screw shaft 46 becomes the target speed VI. In S130, the shaft position acquisition section 564 starts counting the cumulative rotation speed of the motor 2. Note that the processes of S130 and S120 can be executed in either order or simultaneously.

[0086] In S140, the shaft position acquisition section 564 confirms whether or not the screw shaft 46 has reached the deceleration position PI. Specifically, the shaft position acquisition section 564 monitors the cumulative rotation speed of the motor 2, and confirms whether or not the counting result of the cumulative rotation speed of the motor 2 from S130 has reached the cumulative rotation speed TH. If the cumulative rotation speed of the motor 2 has not reached the cumulative rotation speed TH (S140: NO), the shaft position acquisition section 564 shifts the process to S142.

[0087] In S142, the shaft position acquisition section 564 monitors the output of the detection signal from the first sensor 481, and confirms whether or not the brake position P2 has been reached. For example, when the trigger 151 is released during the movement in the rear direction before the screw shaft 46 reaches the stop position PE, the screw shaft 46 sometimes reaches the brake position P2 before the cumulative rotation speed of the motor 2 reaches the cumulative rotation speed TH.

[0088] If the output of the detection signal from the first sensor 481 is OFF (S142: NO), the shaft position acquisition section 564 determines that the screw shaft 46 has not reached the brake position P2, and returns the process to S140. When the output of the detection signal from the first sensor 481 is switched from OFF to ON (S142: YES), the shaft position acquisition section 564 determines that the screw shaft 46 has reached the brake position P2, and shifts the process to S170.

[0089] In S140, when the cumulative rotation speed of the motor 2 reaches the cumulative rotation speed TH (S140: YES), the shaft position acquisition section 564 determines that the screw shaft 46 has reached the deceleration position PI, and shifts the process to S150. In S150, the motor control section 562 starts deceleration of the rotation speed of the motor 2 so that the moving speed of the screw shaft 46 becomes the target speed V2 from the target speed VI.

[0090] In S160, the shaft position acquisition section 564 monitors the output of the detection signal from the first sensor 481, and confirms whether or not the screw shaft 46 has reached the braking position P2. If the screw shaft 46 has not reached the braking position P2 (S160: No), the shaft position acquisition section 564 returns the process to S160. When the output of the detection signal from the first sensor 481 is switched from off to on (S160: Yes), the shaft position acquisition section 564 determines that the screw shaft 46 has reached the braking position P2, and transfers the process to S170. In S170, the motor control section 562 brakes the motor 2 using the short-circuit brake, stops the screw shaft 46, and ends the process.

[0091] In Figure 12 An example of a case in which the screw shaft 46 moves to the stop position PE by rearward movement, and then moves from the stop position PE to the initial position PS by forward movement is shown in FIG. 12. At time tl, the switch 152 is turned on by a press operation of the trigger 151. The motor control section 562 drives the motor 2 in the forward direction at such a manner that the moving speed of the screw shaft 46 becomes the target speed VI. At time t2, the screw shaft 46 reaches the outer detection position PD, and the detection signal from the first sensor 481 is switched from on to off. The shaft position acquisition section 564 starts counting the cumulative rotation speed of the motor 2.

[0092] At time t3, the screw shaft 46 reaches the rearward detection position PB, and the detection signal from the second sensor 482 is switched from off to on. The motor control section 562 brakes the motor 2. At time t4, the screw shaft 46 stops at the stop position PE, and the rearward movement of the screw shaft 46 is completed.

[0093] At time t5, the switch 152 is turned off by a release operation of the trigger 151. The motor control section 562 drives the motor 2 in the reverse direction at such a manner that the moving speed of the screw shaft 46 becomes the target speed VI. The shaft position acquisition section 564 starts counting the cumulative rotation speed of the motor 2. At time t6, the cumulative rotation speed of the motor 2 reaches the cumulative rotation speed TH, and the motor control section 562 drives the motor 2 so as to decelerate the moving speed of the screw shaft 46 to the target speed V2.

[0094] At time t7, the screw shaft 46 reaches the braking position P2, and the detection signal from the first sensor 481 is switched from off to on. The motor control section 562 brakes the motor 2 using the short-circuit brake. At time t8, the screw shaft 46 stops at the initial position PS, and the forward movement of the screw shaft 46 is completed.

[0095] As explained above, according to the fastening tool 1 of this embodiment, during the forward movement of the lead screw shaft 46, when the lead screw shaft 46 reaches the deceleration position P1, the moving speed of the lead screw shaft 46 is decelerated from the target speed V1 to the target speed V2 by PWM control. Since the drive of the motor 2 is stopped after the moving speed of the lead screw shaft 46 is decelerated, deviation of the stopping position when the lead screw shaft 46 stops at the initial position PS during forward movement can be suppressed or prevented. Therefore, it is possible to suppress or prevent the pin holding part 165 from failing to properly hold the pin 91.

[0096] In the fastening tool 1 of this embodiment, when the cumulative rotational speed of the motor 2, obtained by the shaft position acquisition unit 564 as it moves forward of the lead screw shaft 46, reaches the cumulative rotational speed TH, it is determined that the deceleration position P1 has been reached. Therefore, it is possible to eliminate the need for a component for detecting the deceleration position P1, thereby enabling the detection of the deceleration position P1 with a smaller number of parts. In addition, the deceleration position P1 can be easily set or changed.

[0097] B. Second Implementation Method: like Figure 13 As shown, in the drive control of the motor 2 executed by the fastening tool 1 according to the second embodiment, the difference from the first embodiment is that S144 to S152 are provided instead of S140, S142, and S150, but the structure is the same as that in the first embodiment. In this embodiment, the moving speed of the lead screw 46 decelerates when it reaches the target speed V1 while moving forward.

[0098] In S144, the motor control unit 562 monitors the cumulative speed of the motor 2 and confirms whether the moving speed of the lead screw shaft 46 has reached the target speed V1. When the cumulative speed of the motor 2 reaches the specified value and the moving speed of the lead screw shaft 46 reaches the target speed V1 (S144: Yes), the shaft position acquisition unit 564 transfers the processing to S146.

[0099] In S146, the shaft position acquisition unit 564 calculates the distance from the position of the lead screw shaft 46 (hereinafter also referred to as the "arrival position") to the braking position P2 at the moment when the target speed V1 is reached. In this embodiment, the distance from the arrival position to the braking position P2 is expressed as the cumulative rotational speed of the motor 2 used to move from the arrival position to the braking position P2. In this embodiment, since the counting of the cumulative rotational speed of the motor 2 starts from the detection external position PD, which is approximately the same as the braking position P2, the shaft position acquisition unit 564 can obtain the distance from the arrival position to the braking position P2 (the cumulative rotational speed of the motor 2) by obtaining the cumulative rotational speed of the motor 2 at the arrival position.

[0100] In S148, the motor control section 562 calculates a negative acceleration using the distance from the arrival position to the braking position P2 (cumulative rotation speed of the motor 2). The "negative acceleration" refers to a deceleration that decelerates the object. In the present embodiment, the moving speed of the screw shaft 46 at the arrival position is the target speed VI, and the moving speed at the braking position P2 is the target speed V2, and the motor control section 562 calculates the negative acceleration as a constant value as a so-called negative constant acceleration straight movement. By making the acceleration a constant value, the calculation cost of the acceleration can be suppressed. In S152, the motor control section 562 drives the motor 2 at the calculated negative acceleration as a constant value until the screw shaft 46 reaches the braking position P2, and decelerates the moving speed of the screw shaft 46. Note that the acceleration is not limited to a constant, and can be a variable.

[0101] As shown in FIG. 15B, at time t5, the motor control section 562 drives the motor 2 in the reverse direction so that the moving speed of the screw shaft 46 becomes the target speed VI by the release operation of the trigger 151, as in the first embodiment described above. At time t6b, when the moving speed of the screw shaft 46 reaches the target speed VI, the shaft position acquisition section 564 acquires the arrival position, and calculates the distance from the arrival position to the braking position P2 (cumulative rotation speed TH2 of the motor 2). The motor control section 562 calculates the negative acceleration dV using the cumulative rotation speed TH2 of the motor 2 from the arrival position to the braking position P2. The motor control section 562 drives the motor 2 so that the moving speed of the screw shaft 46 is decelerated at the negative acceleration dV. ​

[0102] According to the tightening tool 1 of the present embodiment, the motor control section 562 stops the drive of the motor 2 after decelerating the moving speed at the calculated negative acceleration dV. As in the first embodiment described above, since the drive of the motor 2 is stopped after the moving speed of the screw shaft 46 is decelerated, the deviation of the position at which the screw shaft 46 stops at the initial position PS when moving forward can be suppressed or prevented.

[0103] In the tightening tool 1 of the present embodiment, the motor control section 562 calculates the negative acceleration dV using the distance from the arrival position to the braking position P2, and drives the motor 2 so that the moving speed of the screw shaft 46 is decelerated at the calculated negative acceleration dV. Since the negative acceleration is calculated from the arrival position, the moving speed at the braking position P2 is switched to the target speed V2 even in a case where the arrival position has varied due to a difference in the timing of the release operation of the trigger 151, for example. Therefore, the deviation of the position at which the screw shaft 46 stops at the initial position PS due to the variation of the arrival position can be suppressed or prevented.

[0104] C. Other Embodiments ​(C1) In the above-described first embodiment, an example is shown in which the deceleration position PI is set at a position at which the cumulative rotation speed of the motor 2 reaches the predetermined cumulative rotation speed TH after the lead screw shaft 46 starts moving forward. In contrast to this, the deceleration position PI can also be set at a position that is a predetermined distance (cumulative rotation speed of the motor 2) rearward from the initial position PS. In this case, the moving speed of the lead screw shaft 46 can be decelerated at a prescribed position regardless of the position at which the lead screw shaft 46 starts moving forward.

[0105] (C2) In the above-described second embodiment, an example is shown in which the motor control section 562 switches the rotation speed of the motor 2 per unit time by PWM control that changes the duty ratio output to the motor 2. In contrast to this, the motor control section 562 can switch the moving speed of the lead screw shaft 46 by constant rotation speed control of the motor 2. The "constant rotation speed control" refers to control that adjusts the drive voltage of the motor 2 in such a way that the rotation speed of the motor shaft 25 per unit time is a predetermined target rotation speed or lower. By constant rotation speed control, the moving speed of the lead screw shaft 46 can be switched with high precision. For example, the motor control section 562 can perform constant rotation speed control of the motor 2 so that the target rotation speed of the motor 2 is 50% or more and 75% or less of the target rotation speed when moving forward from the stop position PE to the initial position PS.

[0106] (C3) The structure of the motor 2, the transmission mechanism 3, and the drive mechanism 4 can be changed as appropriate. For example, the motor 2 can employ a brush motor, or an alternating current motor. For example, the number of planetary gear mechanisms of the planetary reducer 31 or the configuration of the intermediate shaft 33, or the like can be changed. The drive mechanism 4 can employ a feed screw mechanism having a nut with internal threads formed on the inner periphery and a lead screw shaft with external threads formed on the outer periphery and directly screwed with the nut, for example, instead of the ball screw mechanism 40 having the nut 41 and the lead screw shaft 46 that engages with the nut via balls. In the ball screw mechanism 40, the lead screw shaft 46 can be configured so that the movement of the lead screw shaft 46 in the front-rear direction is restricted and the lead screw shaft 46 is supported so as to be rotatable, and the nut 41 moves in the front-rear direction as the lead screw shaft 46 rotates. In this case, the pin holding section 165 is directly or indirectly linked to the nut 41.

[0107] (C4) In the above-described embodiments, the first sensor 481 and the second sensor 482 employ magnetic field detection type sensors, but other types of sensors (for example, optical type sensors such as optical interrupters) or mechanical type switches can also be employed.

[0108] (C5) In each of the above-described embodiments, an example is shown in which the controller 156 is constituted by a computer including a CPU, a ROM, a RAM, and the like. In contrast to this, the controller can be constituted by a programmable logic device such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), and the like, for example. The drive control processing of each of the above-described embodiments can be realized by the CPU executing a program stored in the ROM. In this case, the program can be stored in advance in the ROM of the controller 156, or in a nonvolatile memory in the case where the controller 156 includes a nonvolatile memory. Alternatively, the program can be recorded in an external storage medium (for example, a USB memory) that can read data. The drive control processing of the above-described embodiments and modified examples can be distributed processing by a plurality of control circuits.

[0109] The present application is not limited to the above-described embodiments, and can be realized by various structures without departing from the gist thereof. For example, the technical features in the embodiments corresponding to the technical features in each of the modes recited in the column of the summary of the application can be appropriately replaced or combined, for a part or all of the technical problems described above or for a part or all of the effects described above. In addition, the technical features can be appropriately deleted if not described as essential technical features in the present specification.

Claims

1. A fastening tool for fastening working materials via a fastener having a pin and a cylindrical portion, characterized in that, It comprises a motor, a housing, a pin holding part, a drive mechanism, a position acquisition part, and a motor control part, wherein, The motor includes a motor shaft; The housing houses the motor; The pin holding part is configured to hold the pin; The drive mechanism is connected to the pin holding part. The drive mechanism is configured to perform rearward movement and forward movement. The rearward movement refers to the movement from the initial position to the rearward along the drive axis that defines the front-rear direction of the fastening tool by rotating the motor shaft in the forward direction. The forward movement refers to the movement from the rear to the initial position along the drive axis by rotating the motor shaft in the reverse direction. The position acquisition unit is configured to acquire the relative position of the drive mechanism with respect to the housing in the front-rear direction; The motor control unit performs drive control of the motor and is configured to switch the moving direction and moving speed of the drive mechanism. The motor control unit begins the forward movement of the drive mechanism at the first speed. During the forward movement, when the obtained relative position reaches a deceleration position further behind the initial position, the moving speed is reduced to a second speed, slower than the first speed, by using PWM control that changes the duty cycle of the output to the motor. When the obtained relative position reaches a predetermined braking position that is forward of the deceleration position and backward of the initial position, the drive of the motor is stopped.

2. A fastening tool for fastening working materials via a fastener having a pin and a cylindrical portion, characterized in that, It comprises a motor, a housing, a pin holding part, a drive mechanism, a position acquisition part, and a motor control part, wherein, The motor includes a motor shaft; The housing houses the motor; The pin holding part is configured to hold the pin; The drive mechanism is connected to the pin holding part. The drive mechanism is configured to perform rearward movement and forward movement. The rearward movement refers to the movement from the initial position to the rearward along the drive axis that defines the front-rear direction of the fastening tool by rotating the motor shaft in the forward direction. The forward movement refers to the movement from the rear to the initial position along the drive axis by rotating the motor shaft in the reverse direction. The position acquisition unit is configured to acquire the relative position of the drive mechanism with respect to the housing in the front-rear direction; The motor control unit performs drive control of the motor and is configured to switch the moving direction and moving speed of the drive mechanism. The motor control unit begins the forward movement of the drive mechanism at the first speed. During the forward movement, when the obtained relative position reaches a deceleration position further behind the initial position, the movement speed is reduced to a second speed, slower than the first speed, by constant speed control that adjusts the motor's drive voltage so that the rotational speed of the motor shaft per unit time becomes a predetermined target speed. When the obtained relative position reaches a predetermined braking position that is forward of the deceleration position and backward of the initial position, the drive of the motor is stopped.

3. A fastening tool that fastens working materials via a fastener having a pin and a cylindrical portion, characterized in that, It comprises a motor, a housing, a pin holding part, a drive mechanism, a position acquisition part, and a motor control part, wherein, The motor includes a motor shaft; The housing houses the motor; The pin holding part is configured to hold the pin; The drive mechanism is connected to the pin holding part. The drive mechanism is configured to perform rearward movement and forward movement. The rearward movement refers to the movement from the initial position to the rearward along the drive axis that defines the front-rear direction of the fastening tool by rotating the motor shaft in the forward direction. The forward movement refers to the movement from the rear to the initial position along the drive axis by rotating the motor shaft in the reverse direction. The position acquisition unit is configured to acquire the relative position of the drive mechanism with respect to the housing in the front-rear direction; The motor control unit performs drive control of the motor and is configured to switch the moving direction and moving speed of the drive mechanism. The motor control unit begins the forward movement of the drive mechanism at the first speed. During the forward movement, when the moving speed reaches the first speed, a negative acceleration is determined such that the moving speed at the braking position, which is a predetermined distance behind the initial position, becomes a second speed that is slower than the first speed. The moving speed is then decelerated using the determined acceleration. When the obtained relative position reaches the braking position, the drive of the motor is stopped.

4. The fastening tool according to claim 1 or 2, characterized in that, The position acquisition unit acquires the cumulative rotational speed of the motor shaft and uses the acquired cumulative rotational speed of the motor shaft to acquire the relative position.

5. The fastening tool according to claim 4, characterized in that, If the cumulative rotational speed obtained by the position acquisition unit during the forward movement reaches a predetermined cumulative rotational speed, it is determined that the drive mechanism has reached the deceleration position.

6. The fastening tool according to claim 4, characterized in that, The cumulative rotational speed of the motor shaft from the starting position of the forward movement to the deceleration position is configured such that it is less than the cumulative rotational speed of the motor shaft from the starting position of the cumulative rotational speed counting of the motor shaft to the starting position of the forward movement during the rearward movement by a predetermined cumulative rotational speed.

7. The fastening tool according to claim 3, characterized in that, The position acquisition unit acquires the cumulative rotational speed of the motor shaft, and uses the acquired cumulative rotational speed of the motor shaft to obtain the position reached when the moving speed reaches the first speed. Calculate the distance from the obtained arrival position to the braking position. The motor control unit uses the calculated distance from the arrival position to the braking position to calculate the acceleration, and uses the calculated acceleration to decelerate the moving speed.

8. The fastening tool according to claim 7, characterized in that, The motor control unit decelerates the moving speed with a certain negative acceleration corresponding to the distance obtained from the arrival position to the braking position.

9. The fastening tool according to any one of claims 4 to 8, characterized in that, It also has a detection object and a braking position detection unit, among which, The detection object is disposed on the driving mechanism and moves integrally with the driving mechanism; The braking position detection unit is configured to detect the detection object provided by the drive mechanism when the drive mechanism is positioned in the braking position. During the rearward movement, the position acquisition unit begins acquiring the cumulative rotational speed of the motor shaft at the moment when the detection result of the braking position detection unit switches from a detected state to a non-detected state where the detected object is not detected.

10. The fastening tool according to claim 3, or any one of claims 7 to 9 directly or indirectly dependent on claim 3, characterized in that, The motor control unit switches the moving speed by using PWM control that changes the duty cycle output to the motor.

11. The fastening tool according to claim 3, or any one of claims 7 to 9 directly or indirectly dependent on claim 3, characterized in that, The motor control unit performs constant speed control by adjusting the drive voltage of the motor in a manner that the rotational speed of the motor shaft per unit time becomes a predetermined target speed. The movement speed is switched by switching the target rotation speed.

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

13. The fastening tool according to any one of claims 1 to 12, characterized in that, The drive mechanism includes a nut and a shaft, wherein, The nut is driven to rotate around the drive axis by the power of the motor; The shaft is connected to the pin holding part, and the shaft is configured to perform the rearward movement by rotating the motor shaft in the forward direction and to perform the forward movement by rotating the motor shaft in the reverse direction.

14. The fastening tool according to any one of claims 1 to 13, characterized in that, It has a detection object and a rear braking position detection unit, wherein, The detection object is disposed on the driving mechanism and moves integrally with the driving mechanism; The rear braking position detection unit is configured to detect the detection object set on the drive mechanism when it is positioned in a rear braking position that is further rear than the braking position. When the detection object is detected by the rear braking position detection unit, the motor control unit stops driving the motor.

15. The fastening tool according to any one of claims 1 to 14, characterized in that, It also has a trigger capable of accepting a pressing operation and releasing the pressing operation. When the trigger receives the pressing operation, the motor control unit drives the motor to rotate the motor shaft in the forward direction, and when the trigger receives the releasing operation, it drives the motor to rotate the motor shaft in the reverse direction.

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