FASTENING TOOL

Abstract

A fastening tool comprises a drive mechanism connected to perform a reverse and a forward movement, a position sensing part configured to obtain a relative position of the drive mechanism, and a motor control part configured to change a direction and speed of movement of the drive mechanism.The motor control section starts the forward movement of the drive mechanism so that the movement speed reaches a first speed, reduces the movement speed to a second speed that is lower than the first speed by means of a PWM control to change a duty cycle that is output to the motor when the obtained relative position reaches a braking position behind the initial position during the forward movement, and stops driving the motor when the obtained relative position reaches a predetermined braking position in front of the braking position and behind the initial position.

Description

TECHNICAL AREA

[0001] The present disclosure relates to a fastening tool. STATE OF THE ART

[0002] A fastening tool is known that is configured to fasten workpieces together by means of a fastener by pulling a pin of the fastener. In such a fastening tool, a drive mechanism connected to a pin gripping element is moved rearward from an initial position by the power of a motor to pull the pin rearward along a drive axis. Subsequently, the drive mechanism is moved forward toward the initial position by the power of the motor. For example, JP 2019-000892A discloses a fastening tool in which the motor is braked to stop the drive mechanism when the drive mechanism, moving toward the initial position, enters a detection range of a sensor located in the initial position. BRIEF SUMMARY

[0003] With this state of the art, the stop position at which the drive mechanism stops in the initial position can vary. This can create a problem where the pen gripper cannot grip the pen correctly.

[0004] The present revelation can be realized in the following aspects:

[0005] According to a first aspect of the present disclosure, a fastening tool is provided which is configured to fasten workpieces by means of a fastening element comprising a pin and a cylindrical part. The fastening tool comprises a motor having a motor shaft, a housing that receives the motor, a pin gripping part configured to grip the pin, a drive mechanism connected to the pin gripping part configured to perform a reverse movement to move backward from an initial position along a drive axis defining a front-back direction of the fastening tool by a normal rotation of the motor shaft, and a forward movement to move forward to the initial position along the drive axis by a reverse rotation of the motor shaft, a position sensing part configured toThe system detects (maintains) a relative position of the drive mechanism in the front-back direction relative to the housing, and incorporates a motor control section configured to perform drive control of the motor to change the direction and speed of movement of the drive mechanism. The motor control section initiates the forward movement of the drive mechanism so that the movement speed reaches a first speed, reduces the movement speed to a second speed lower than the first speed by means of PWM control to change a duty cycle (duty cycle) output to the motor when the received (detected) relative position reaches a deceleration position behind (behind) the initial position during the forward movement, and stops driving the motor.when the obtained (detected) relative position reaches a predetermined braking position in front of the braking position and behind (behind) the initial position.

[0006] According to this principle, the motor's operation is stopped after the drive mechanism's speed is reduced, thus minimizing or preventing deviations in the drive mechanism's stop position when it halts during forward movement. The motor shaft's rotational speed is precisely controlled by the PWM controller, ensuring accurate adjustment of the drive mechanism's speed. This prevents or avoids the issue of the pen gripper failing to engage the pen correctly.

[0007] According to a second aspect of the present disclosure, a fastening tool is provided which is configured to fasten workpieces by means of a fastening element comprising a pin and a cylindrical part. The fastening tool comprises a motor having a motor shaft, a housing that receives the motor, a pin gripping part configured to grip the pin, a drive mechanism connected to the pin gripping part and configured to perform a reverse movement to move backward from an initial position along a drive axis defining a front-back direction of the fastening tool by a normal rotation of the motor shaft, and a forward movement to move forward to the initial position along the drive axis by a reverse rotation of the motor shaft, and a position sensing part configured toThe system detects (maintains) a relative position of the drive mechanism in the front-back direction relative to the housing, and incorporates a motor control section configured to perform drive control of the motor to change the direction and speed of movement of the drive mechanism. The motor control section initiates the forward movement of the drive mechanism so that the movement speed reaches a first speed, reduces the movement speed to a second speed lower than the first speed by means of a constant-speed rotary control to set (adjust) a drive voltage of the motor so that a predetermined number of revolutions per unit time of the motor shaft reaches a predetermined target number of revolutions when the detected relative position reaches a braking position behind the initial position during forward movement, and stops the motor driving.when the obtained (detected) relative position reaches a predetermined braking position in front of the braking position and behind (behind) the initial position.

[0008] According to this principle, the motor's drive is stopped after the drive mechanism's speed is reduced, thus minimizing or preventing deviations in the drive mechanism's stop position when it stops during forward movement. The drive mechanism's speed is precisely controlled by the constant-speed rotary controller. This prevents or avoids the problem of the pen gripper failing to properly grip the pen.

[0009] According to a third aspect of the present disclosure, a fastening tool is provided which is configured to fasten workpieces by means of a fastening element comprising a pin and a cylindrical part. The fastening tool comprises a motor having a motor shaft, a housing that receives the motor, a pin gripping element configured to grip the pin, a drive mechanism connected to the pin gripping element and configured to perform a reverse movement to move backward from an initial position along a drive axis defining a front-back direction of the fastening tool by a normal rotation of the motor shaft, and a forward movement to move forward from the initial position along the drive axis by a reverse rotation of the motor shaft, and a position sensing element configured toThe system detects (maintains) the relative position of the drive mechanism in the front-back direction relative to the housing, and includes a motor control section configured to perform drive control of the motor to change the direction and speed of movement of the drive mechanism. The motor control section initiates the forward movement of the drive mechanism so that the movement speed reaches an initial speed, determines a negative acceleration so that the movement speed is reduced to a second speed, which is lower than the first speed, at a braking position located at a predetermined distance rearward from the initial position, and reduces the movement speed with the predetermined acceleration when the movement speed reaches the first speed during the forward movement, and stops driving the motor.when the detected (obtained) relative position reaches the braking position.

[0010] According to this principle, the motor's operation is stopped after the drive mechanism's speed is reduced, thus minimizing or preventing deviations in the drive mechanism's stop position when it stops during forward movement. This, in turn, avoids or prevents the problem of the pen gripper not being able to grip the pen correctly.

[0011] The present disclosure can also be implemented in various other applications besides fastening tools, such as a control method for controlling a fastening tool, a computer program for implementing the control method, and a non-temporary storage medium that controls the computer program. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is an explanatory view showing an example of a fastening means that can be used with a fastening tool according to the present disclosure. Fig. Figure 2 is a longitudinal cross-sectional view of the fastening tool with a spindle shaft in an initial position. Fig. Figure 3 is an explanatory view showing a magnified view of the rear part of the fastening tool. Fig. Figure 4 is a cross-sectional view of a rear part of the fastening tool. Fig. Figure 5 is an explanatory view showing a magnified view of the front part of the fastening tool. Fig. Figure 6 is a block diagram illustrating the electrical structure of the fastening tool. Fig. Figure 7 is a block diagram to represent the internal functional configuration of a controller. Fig. Figure 8 is an explanatory view to illustrate the relationship between the position of the spindle shaft and a first and a second sensor. Fig. Figure 9 is a flowchart of a process for the drive control of a motor during a reverse movement of the spindle shaft. Fig. Figure 10 is a flowchart of a process for the drive control of the motor during a forward movement of the spindle shaft. Fig. Figure 11 is a time diagram to illustrate the operation of each part in a cycle of a fastening process. Fig. Figure 12 is a flowchart of a process for the drive control of the motor according to a second embodiment of the present embodiment. Fig. Figure 13 is a time diagram of a fastening process of the fastening tool according to the second embodiment. DETAILED DESCRIPTION OF THE EXECUTION FORMS

[0012] Representative, non-limiting examples of the present invention are described in detail with reference to the accompanying drawings. This detailed description is intended solely to provide the person skilled in the art with further details regarding the implementation of preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed below can be used separately or in combination with other features and teachings to provide improved tools and methods for manufacturing and using the tools.

[0013] Furthermore, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the invention in the broadest sense and are instead taught only to describe, in particular, representative examples of the invention. Moreover, various features of the representative examples described above and below, as well as of the various independent and dependent claims, can be combined in a manner not specifically and expressly enumerated to create additional useful embodiments of the present teachings.

[0014] All features disclosed in the description and / or the claims shall be disclosed separately and independently of one another for the purpose of the original written disclosure and for the purpose of limiting the claimed subject matter, irrespective of the combinations of features in the embodiments and / or the claims. Furthermore, all ranges of values ​​or information relating to groups of units shall disclose every possible intermediate value or unit for the purpose of the original written disclosure and for the purpose of limiting the claimed subject matter.

[0015] In at least one non-restrictive embodiment according to the present disclosure, the position sensing part can obtain a cumulative number of revolutions of the motor shaft and obtain the relative position using the obtained cumulative number of revolutions of the motor shaft.

[0016] According to this embodiment, the position of the drive mechanism is maintained in a simple manner.

[0017] In addition to or as an alternative to the preceding embodiment, when the cumulative number of revolutions obtained during forward movement reaches a predetermined cumulative number of revolutions, the position sensing part can determine that the obtained relative position of the drive mechanism has reached the braking position.

[0018] According to this embodiment, a sensing element for detecting a detected object, which is provided in the braking position, can be omitted, thus avoiding or reducing an increase in the number of parts of the fastening tool. Furthermore, the braking position can be set and changed more easily than in a case where such a sensing element is provided.

[0019] In addition or alternatively to the preceding embodiments, the cumulative number of revolutions of the motor shaft during forward movement from a starting position of the forward movement to the braking position can be smaller by a predetermined number of revolutions than the cumulative number of revolutions of the motor shaft during reverse movement from a starting position of the counting of the cumulative number of revolutions of the motor shaft during reverse movement to the starting position of the forward movement.

[0020] According to this embodiment, the braking position can be set at the rear (behind) of the starting position for counting the cumulative number of revolutions of the motor shaft using the cumulative number of revolutions of the motor shaft.

[0021] In addition to or as an alternative to the preceding embodiments, the position sensing unit can receive (detect) a cumulative number of motor shaft revolutions. The position sensing unit can receive (detect) an approach position at which the movement speed reaches the initial speed by using the received cumulative number of motor shaft revolutions. The position sensing unit can calculate a distance (distance) from the received (detected) approach position to the braking position. The motor control unit can calculate the negative acceleration using the calculated distance from the approach position to the braking position and reduce the movement speed by the calculated negative acceleration.

[0022] According to this embodiment, even if the reaching position varies, the movement speed is reduced to the second speed at the braking position. Thus, deviations in the stop position of the drive mechanism due to deviations in the reaching position can be reduced or prevented.

[0023] In addition to or as an alternative to the preceding embodiments, the motor control unit can reduce the speed of movement with a constant negative acceleration corresponding to the distance from the achieved target position to the braking position.

[0024] According to this embodiment, the effort required to calculate the acceleration is reduced.

[0025] In addition to or as an alternative to the preceding embodiments, the fastening tool may further comprise a detected object provided by the drive mechanism and moving integrally with the drive mechanism, and a brake position sensing element configured to detect the detected object when the drive mechanism is in the braking position. The position sensing element may initiate the detection (recording) of the cumulative number of motor shaft revolutions at the moment when, during reverse movement, a detection result of the brake position sensing element changes from a detection state, in which the detected object is detected, to a non-detection state, in which the detected object is not detected.

[0026] According to this embodiment, the accuracy in determining the position of the drive mechanism is improved compared to a case in which the counting of the cumulative number of revolutions of the motor shaft is started at the time when the drive mechanism starts the reverse movement.

[0027] In addition to or as an alternative to the preceding embodiments, the motor control part can change the speed of movement by means of a PWM control to change a duty cycle (duty time) output to the motor.

[0028] According to this embodiment, the rotational speed of the motor shaft is accurately changed by the PWM control, so that the speed of movement of the drive mechanism is accurately changed.

[0029] In addition to or as an alternative to the preceding embodiments, the motor control unit can implement a constant-speed rotary control (constant-speed rotary control) for setting a drive voltage of a motor so that a predetermined target number of revolutions per unit of time of the motor shaft is achieved. The motor control unit can change the speed of movement by changing the target number of revolutions.

[0030] According to this embodiment, the speed of movement of the drive mechanism is accurately changed by the constant-speed rotary control.

[0031] In addition to or as an alternative to the preceding embodiments, the motor control unit can stop the motor by short-circuit braking to short-circuit the motor's terminals.

[0032] According to this embodiment, the time required to stop the motor is reduced. Furthermore, the braking distance of the drive mechanism is shortened, thus reducing or preventing deviation (variation) in the stop position of the drive mechanism.

[0033] In addition to or as an alternative to the preceding embodiments, the drive mechanism may include a nut which is driven to rotate about the drive axis by a power of the motor, and a shaft which is connected to the pin gripping part and is configured to perform the reverse movement by a normal rotation of the motor shaft and to perform the forward movement by a reverse rotation of the motor shaft.

[0034] According to this embodiment, the direction and speed of movement of the drive mechanism can be accurately changed by a so-called feed spindle mechanism.

[0035] In addition to or as an alternative to the preceding embodiments, the fastening tool may further comprise a detected object provided by the drive mechanism and moving integrally with the drive mechanism, and a rear brake position detection element configured to detect the detected object when the drive mechanism is in a rear brake position behind the brake position. The motor control element may stop the motor from driving when the detected object is detected by the rear brake position detection element.

[0036] According to this embodiment, the drive mechanism in the rear brake position can be detected in a simpler way than in a case where the position of the drive mechanism is determined using the number of revolutions of the engine.

[0037] In addition to or as an alternative to the preceding embodiments, the fastening tool may further include a push button configured to be pressed or released by a user. The motor control unit can drive the motor to rotate the motor shaft in a normal direction when the push button is pressed, while the motor is driven to rotate the motor shaft in a reverse direction when the push button is released.

[0038] According to this embodiment, the user can easily switch between the forward and reverse movement of the drive mechanism by pressing the push button. A. First embodiment A.1 Structure of the fastening device:

[0039] Fig. Figure 1 shows an example of a fastening device that can be used with a fastening tool 1 according to the present disclosure. The fastening device 9 has a pin 91 and a collar 95. The fastening device 9 is of a break-away type (specifically, a multi-part countersunk fastener) in which a portion of a shaft part 911 of the pin 91, which is referred to as the pin tail or mandrel, is broken off. The collar 95 is generally cylindrical and configured to allow the shaft part 911 to be inserted through it. The collar 95 is an example of the “cylindrical part”. A2. The external structure of fastening tool 1:

[0040] The fastening tool 1, which is configured to fasten workpieces using the fastening device 9, is now referred to as Fig. 2 as an example of the fastening tool of the present disclosure. As in Fig. As shown in Figure 2, the outer casing of the fastening tool 1 is formed by an outer housing 11, a handle 15, and a nose 16. The outer housing 11 has a generally rectangular, box-like shape and extends along a predetermined drive axis A1. As shown in Figure 2, the outer casing 11 is formed by a handle 15, a handle 15, and a nose 16. The outer housing 11 has a generally rectangular, box-like shape and extends along a predetermined drive axis A1. Fig. As shown in Figure 2, the outer housing 11 accommodates a motor 2, a drive mechanism 4, and a transmission mechanism 3. An inner housing 13 is fixed inside the outer housing 11. The outer housing 11 and the inner housing 13 form an integral housing 10.

[0041] The nose 16 is arranged such that it extends along the drive axis A1. The nose 16 has a cylindrical anvil 161 and a pin gripping element 165, which is arranged inside the anvil 161. The anvil 161 is connected to an end part of the outer housing 11 in the axial direction. A collecting container 7 is configured to collect the shank part 911, which is separated from the fastener 9 during a fastening operation, and is removably attached to the other end part of the outer housing 11.

[0042] The handle 15 is configured to be held by a user. The handle 15 projects axially from substantially the center of the outer housing 11 in a direction that crosses the drive axis A1 (in a direction substantially perpendicular to the drive axis A1 in this embodiment).

[0043] In this specification, the direction of the fastening tool 1 is defined as the extension direction of the drive axis A1 (or the axial direction of the outer housing 11) as a front-back direction of the fastening tool 1. In the front-back direction, the side on which the nose 16 is located is defined as a front side, and the side on which the collection container 7 is located is defined as a rear side. Furthermore, a direction perpendicular to the drive axis A1 and corresponding to the extension direction of the handle 15 is defined as an up-down direction. In the up-down direction, the side on which the outer housing 11 is located is defined as an upper side, and the side of a projecting end (free end) of the handle 15 is defined as a lower side. A direction perpendicular to both the front-back and up-down directions is defined as a left-right direction.

[0044] An upper end portion of the handle 15 serves as a base end portion, which is connected to the outer housing 11. A push button 151 is provided on an upper end portion of the handle 15 and is configured to be pressed and released by a user. A battery mounting part 158 ​​is provided on a lower end portion of the handle 15 and is configured such that a battery 159 can be removably mounted to it. The battery 159 is a rechargeable power source, which is, for example, a known battery pack or a secondary battery, such as a lithium-ion battery, which has a plurality of cells. The battery 159 supplies power to various parts of the fastening tool 1 and the motor 2.

[0045] The fastening tool 1 is configured to fasten workpieces W1 and W2 together using the fastening element 9. When part of the shank 911 of the fastening element 9 is inserted into a front end portion of the nose 16 of the fastening tool 1, the fastening element 9 is held by the pin gripping part 165 (described later) while engaging with a front end portion of the anvil 161.

[0046] A3. The structures of the elements arranged within the fastening tool 1: The structures of elements arranged within the fastening tool 1 are now described with reference to Fig. 3, Fig. 4 to Fig. 5 described. The housing 10 accommodates the motor 2, the drive mechanism 4, which is configured to be driven by power from the motor 2, and the transmission mechanism 3, which is configured to transmit power from the motor 2 to the drive mechanism 4.

[0047] Motor 2, for example, is a brushless direct current (DC) motor. As shown in Fig. As shown in Figure 3, the motor 2 is housed in a lower rear end section of the outer casing 11. In this embodiment, the entire motor 2 assembly is located below the drive axis A1. The motor 2 comprises 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 is configured to extend from the rotor 23 and rotate integrally with it. The motor 2 is positioned such that a rotational axis A2 of the motor shaft 25 extends parallel to the drive axis A1 below the drive axis A1. The rotational axis A2 extends in the front-to-back direction. A front end section of the motor shaft 25 projects into a reduction gear housing 30. A fan 27 for cooling the motor 2 is fixed to a rear end section of the motor shaft 25.

[0048] As in Fig. As shown in Figure 3, the transmission mechanism 3 comprises a planetary reduction gear (planetary gear reduction device) 31, an intermediate shaft 33, and a main drive gear 35. The planetary reduction gear 31 is located at the front of the motor 2. The rotational power is transmitted from the motor shaft 25 to the planetary reduction gear 31. In a power transmission path from the motor 2 to a ball screw mechanism 40 of the drive mechanism 4, the planetary reduction gear 31 increases the torque of the motor 2 and transmits the torque to the intermediate shaft 33.

[0049] The planetary reduction gear 31 comprises two sets of planetary gear mechanisms and the reduction gear housing 30, which is made of synthetic resin. The reduction gear housing 30 is located at the front of the motor 2 and fixed to the outer housing 11. The reduction gear housing 30 accommodates 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 located in the planetary gear mechanism on the upstream side of the planetary reduction gear 31. A carrier 313 is located in the planetary gear mechanism on the downstream side of the planetary reduction gear 31. The carrier 313 is a final output shaft of the planetary reduction gear 31.

[0050] The intermediate shaft 33 is rotatable and arranged coaxially with the motor shaft 25. A rear end section of the intermediate shaft 33 is connected to the support 313. Thus, the intermediate shaft 33 rotates integrally with the support 313. The drive gear 35 is fixed to an outer circumference of a front end section of the intermediate shaft 33. The drive gear 35 meshes with an output gear 411, which is formed on the outer circumference of a nut 41 (described later) and transmits the rotational power of the intermediate shaft 33 to the nut 41. The drive gear 35 and the output gear 411 form a speed reduction gear mechanism.

[0051] As in Fig. As shown in Figure 3, the drive mechanism 4 is connected to the pen gripping part 165, which will be described later (see Figure 3). Fig. 5) The drive mechanism 4 moves in the forward-backward direction along the drive axis A1 by means of a power from the motor 2 and moves the pin gripping part 165 in the forward-backward direction. In this embodiment, the drive mechanism 4 is formed by the ball screw mechanism 40, which is housed in an upper part of the outer casing 11. As shown in Fig. 3 and Fig. As shown in Figure 4, the ball screw mechanism 40 comprises the nut 41 and a spindle shaft 46. The ball screw mechanism 40 is configured to convert a rotation of the nut 41 into a linear movement of the spindle shaft 46 and to move the pin gripper 165 linearly.

[0052] The nut 41 has a hollow cylindrical shape. The inner housing 13 supports the nut 41 in such a way that it is not movable in the forward-backward direction and is rotatable about the drive axis A1. The output gear 411 is formed on an outer circumference of the nut 41. The nut 41 is supported by the inner housing 13 via a pair of radial bearings 412, 413, which are provided on the front and rear sides of the output gear 411, in such a way that it is rotatable about the drive axis A1. The output gear 411 is in mesh with the nut drive gear 35. The nut 41 rotates about the drive axis A1 when the output gear 411 receives the rotational power from the motor 2 via the nut drive gear 35.

[0053] The spindle shaft 46 is a generally elongated cylindrical component that extends along the drive axis A1. The spindle shaft 46 is an example of a "shaft". The spindle shaft 46 is inserted through the nut 41. The spindle shaft 46 engages with the nut 41 so that it is movable in the forward-backward direction along the drive axis A1. A spiral track is formed between the spindle shaft 46 and the nut 41. The spiral track is defined between a spiral groove formed on an inner circumferential surface of the nut 41 and a spiral groove formed on an outer circumferential surface of the spindle shaft 46. A plurality of balls (not shown) are arranged to roll within the spiral track. The spindle shaft 46 engages with the nut 41 via these balls. The spindle shaft 46 is moved linearly in the forward-backward direction along the drive axis A1 by rotating the nut 41.

[0054] As in Fig. As shown in Figure 4, a central portion of a roller retaining element 463 is fixed to a rear end portion of the spindle shaft 46. The roller retaining element 463 has a pair of arms. Each arm is a component that extends perpendicular to the spindle shaft 46 and projects from the central portion of the roller retaining element 463 in the left-right direction. A roller 464 is rotatably held at an end portion of each arm. A pair of roller guides 111, corresponding to the pair of left and right rollers 464, is provided on left and right inner wall portions of the outer housing 11. The roller guides 111 restrict movement of the rollers 464 in the up-down direction. The rollers 464, arranged at each of the roller guides 111, roll along the roller guide 111 in the front-back direction.A rotation of the spindle shaft 46 about the drive axis A1, together with the rotation of the nut 41, is restricted by the rollers 464 coming into contact with the roller guide 111.

[0055] As in Fig. As shown in Figure 3, a magnetic holder 485 is fixed to an upper rear end portion of the spindle shaft 46. A magnet 486 is mounted to an upper end of the magnetic holder 485. The magnet 486 is an example of the "detected object". The magnet 486 is integrated with (on) the spindle shaft 46 and moves integrally in the front-back direction along with the movement of the spindle shaft 46 in the front-back direction.

[0056] A position sensing mechanism 48 is provided in the outer housing 11 and configured to detect the magnet 486. The position sensing mechanism 48 has a first sensor 481 and a second sensor 482. The second sensor 482 is located behind the first sensor 481. The first sensor 481 and the second sensor 482 are, for example, magnetic field detection sensors, and in this embodiment, they are Hall sensors incorporating Hall elements. The first sensor 481 is an example of the "brake position detection part," and the second sensor 482 is an example of the "rear brake position detection part." The first and second sensors 481, 482 are electrically connected to a controller 156 (see Fig. 6) connected via wires (not shown). The first and second sensors 481, 482 each output predetermined signals to the controller 156 upon detecting the presence of the magnet 486 within their respective detection ranges. In this embodiment, the detection results from the first and second sensors 481, 482 are used by the controller 156 for drive control of the motor 2.

[0057] As in Fig. 3 and Fig. As shown in Figure 4, an extension shaft 47 is coaxially connected to and fixed to the rear end portion of the spindle shaft 46 and is integrated with the spindle shaft 46. The spindle shaft 46 and the extension shaft 47, which are integrated together, are hereinafter collectively referred to as the "drive shaft 460". The drive shaft 460 has a through-hole 461 that extends through it along the drive axis A1. The diameter of the through-hole 461 is slightly larger than the maximum diameter of the shaft portion 911 of the fastener 9, which can be used with the fastening tool 1.

[0058] An opening 114 is formed on the drive shaft A1 in the rear end part of the outer housing 11 and connects the inside of the outer housing 11 to the outside. A cylindrical guide sleeve 117 is fixed to the front of the opening 114. The inner diameter of the guide sleeve 117 is essentially equal to the outer diameter of the extension shaft 47. When the spindle shaft 46 is placed in an initial position, which is in Fig. 3 and Fig. As shown in Figure 4, a rear end of the extension shaft 47 is located inside the guide sleeve 117. When the spindle shaft 46 is moved rearward from the initial position in conjunction with the rotation of the nut 41, the extension shaft 47 moves rearward inside the guide sleeve 117.

[0059] As in Fig. 3 and Fig. As shown in Figure 4, a container connection part 113 is formed at the rear end of the outer housing 11. The container connection part 113 is configured such that the collection container 7 for collecting the broken (torn-off) shaft part 911 can be removably attached to it. A user can attach the collection container 7 to the outer housing 11 in such a way that the inner space of the collection container 7 is in communicative communication with the opening 114 via the container connection part 113.

[0060] As in Fig. As shown in Figure 5, the nose 16 has the cylindrical anvil 161, configured to abut the collar 95 of the fastener 9, and the pin gripping part 165, configured to grip the shank part 911 of the fastener 9. The anvil 161 is removably connected to the front end part of the housing 10 via a predetermined connecting element. The pin gripping part 165 is held coaxially within the anvil 161 such that it is slidable along the drive axis A1 relative to the anvil 161.

[0061] The pin gripping part 165 is integrally connected to the spindle shaft 46 via a connecting element 49. This defines a passage 70 extending from a front end of the pin gripping part 165 to the opening 114 of the outer housing 11 along the drive axis A1. The shaft part 911, which is separated from the fastening element 9, passes through the passage 70 and is collected in the collection container 7.

[0062] As in Fig. As shown in Figure 2, the push button 151 is provided on the upper front end part of the handle 15. A switch 152 is located inside the handle 15 behind the push button 151 and is switched on and off according to the actuation of the push button 151.

[0063] A lower end portion of the handle 15 has a rectangular, box-like shape and forms a control housing part 155. A circuit board 150 is mounted in the control housing part 155. The control unit 156 for controlling the operation of the fastening tool 1, a three-phase inverter 201, and a current sensing amplifier 205 are mounted on the circuit board 150, as described below. An actuating element 157 is provided on an upper part of the control housing part 155 and is configured to input various information in response to external actuation by the user.

[0064] When the push button 151 is pressed by a user, the motor 2 is driven, and the drive mechanism 4 is driven by the motor 2. When the pin-gripping part 165 is moved rearward along the drive axis A1 relative to the anvil 161 while gripping the shank part 911 of the fastener 9, the pin 91 is pulled rearward relative to the collar 95. In the case of using the breakaway fastener 9, which is in Fig. As shown in Figure 1, the collar 95 is then deformed and compressed onto the shaft part 911 of the pin 91, and the workpieces W1, W2 are clamped between a head 915 of the pin 91 and the collar 95. Subsequently, the shaft part 911 is torn off and separated from a small-diameter part 913, and the process of fastening the workpieces W1, W2 (to each other) is completed.

[0065] The fastening tool 1 of this embodiment is configured to perform a fastening operation for fastening workpieces using the fastening means 9, with the operation of the drive mechanism 4 to move the pin gripping part 165 backwards from the initial position to a stop position and return it to the initial position as one cycle.

[0066] A4. The electrical structure of fastening tool 1: As in Fig. As shown in Figure 6, the fastening tool 1 comprises the three-phase inverter 201, a Hall sensor 203, and the controller 156. The three-phase inverter 201 has a three-phase bridge circuit that uses six semiconductor switching elements. The three-phase inverter 201 performs a switching operation of each of the switching elements of the three-phase bridge circuit according to a duty cycle indicated (specified) by a control signal from the controller 156. Consequently, a drive pulse corresponding to the duty cycle is supplied to the motor 2. The Hall sensor 203 has three Hall elements arranged according to the respective phases of the motor 2. The Hall sensor 203 outputs a signal to the controller 156 indicating a rotation angle of the rotor 23.

[0067] 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 a voltage via a shunt resistor and outputs a signal amplified by the amplifier to the controller 156.

[0068] As in Fig. As shown in Figure 7, the control unit 156 consists of a computer comprising a CPU 560 as a processor, a memory 566 with ROM and RAM, an interface circuit 568, and a timer (not shown). These elements are interconnected to communicate bidirectionally via an internal bus 565. An external device OD, including the switch 152, the actuator 157, the first and second sensors 481 and 482, and the three-phase inverter 201, which are located in Fig. The components shown in 6 are connected to the interface circuit 568.

[0069] Memory 566 stores programs for executing functions performed by the fastening tool 1 of this embodiment. As in Fig. As shown in Figure 7, the CPU 560 reads and executes the programs stored in the memory 566, so that the controller 156 functions as a motor control unit 562 and as a shaft position sensing unit 564. The shaft position sensing unit 564 is an example of the "position sensing unit" (position maintenance unit, position determination unit).

[0070] The motor control unit 562 controls the driving of the motor 2 based on signals from the external device OD. In this embodiment, the motor control unit 562 changes the direction and speed of movement of the spindle shaft 46 by controlling the driving of the motor 2. The motor control unit 562 controls, for example, the excitation of the motor 2 via the three-phase inverter 201 based on a signal from the Hall sensor 203. Consequently, the rotational speed of the motor 2 is controlled, and the speed of movement of the spindle shaft 46 is changed. In this embodiment, the rotational speed is controlled by a PWM controller.

[0071] The motor control unit 562 can switch the direction of rotation of the rotor 23 of the motor 2 or the direction of rotation of the motor shaft 25 between a normal direction and a reverse direction. The "normal direction" means a direction of rotation for moving the spindle shaft 46 of the drive mechanism 4 backwards relative to the housing 10, and the "reverse direction" means a direction of rotation for moving the spindle shaft 46 of the drive mechanism 4 forwards relative to the housing 10. When the push button 151 is pressed by the user and the switch 152 is turned on, the motor control unit 562 drives the motor 2 to turn the nut 41 in the normal direction and moves the spindle shaft 46 backwards. When the push button 151 is released by the user and the switch 152 is turned off, the motor control unit 562 drives the motor 2 to turn the nut 41 in the reverse direction and moves the spindle shaft 46 forwards.With such a structure, the user can easily switch (toggle) between a forward movement and a backward movement of the spindle shaft 46 by pressing the push button 151.

[0072] The shaft position sensing element 564 detects (receives, determines) the relative position of the drive mechanism 4 in the front-back direction relative to the housing 10 based on signals from the external device OD. In this embodiment, the shaft position sensing element 564 receives the relative position of the spindle shaft 46 of the drive mechanism 4 (hereinafter simply referred to as a "position of the spindle shaft 46"). In this embodiment, the shaft position sensing element 564 receives (detects) the position of the spindle shaft 46 based on the detection results of the first and second sensors 481, 482, the number of revolutions (angle of rotation) of the motor 2 obtained from the Hall sensor 203, the number of drive pulses supplied to the motor 2, and the drive time of the motor 2, or by operation using this information.The “number of revolutions of motor 2” indicates the number of revolutions of the motor shaft 25 and the number of revolutions of the rotor 23. “Obtaining the position of the spindle shaft 46” involves determining the position of the spindle shaft 46 through a calculation (arithmetic operation).

[0073] A5. The relationship between the position of the spindle shaft 46 in the front-back direction and the drive control of the motor 2: The relationship between the drive control of the motor 2 by the fastening tool 1 of the present disclosure and the position of the spindle shaft 46 in the front-back direction is now described with reference to Fig. As described in section 8, the shaft position detection unit 564 detects (receives) the position of the spindle shaft 46 in the forward-reverse direction based on the detection results of the first and second sensors 481, 482 and the cumulative number of revolutions of the motor 2, which is received (detected) by the Hall sensor 203. The motor control unit 562 executes the drive control of the motor 2 according to the detected (received) position of the spindle shaft 46 in the forward-reverse direction.

[0074] As in the lower part of Fig. As shown in Figure 8, an arrow P indicates the direction of movement of the spindle shaft 46 and the magnet 486 during one cycle. In this embodiment, during one cycle of a fastening operation of the fastener 9, the spindle shaft 46 moves backward from an initial position PS to a stop position PE and then moves from the stop position PE back to the initial position PS. As described above, the magnet 486 is integral with the spindle shaft 46, so that the position of the spindle shaft 46 and the pin gripping part 165 corresponds to the position of the magnet 486. For the sake of simplicity, in the following description, the position of the spindle shaft 46 can be indicated with the same symbol as the position of the magnet 486.

[0075] A detection range R1 of the first sensor 481, a detection range R2 of the second sensor 482 and a movement range R3 of the magnet 486 are schematically represented in Fig. Figure 8 shows that when the spindle shaft 46 is in the initial position PS, the magnet 486 is within the detection range R1 of the first sensor 481. If, for example, the spindle shaft 46 does not return accurately to the initial position PS when a cycle of a fastening operation is completed, the pin gripper 165 cannot grip the pin 91 correctly. Therefore, it is preferable to stop the spindle shaft 46 in the initial position PS as accurately as possible.

[0076] As in the middle part of Fig. As shown in Figure 8, when the spindle shaft 46 is in the initial position PS, the first sensor 481 detects the magnet 486 and outputs a detection signal to the controller 156. When the motor 2 is driven and the spindle shaft 46 moves backward, the magnet 486 reaches a non-detection position PD outside the detection range R1. The backward movement of the spindle shaft 46 is also referred to as a "reverse movement" (rear movement). In the non-detection position PD, the output of a detection signal from the first sensor 481 changes from ON to OFF.

[0077] As the spindle shaft 46 moves further rearward from the non-detection position PD, the magnet 486 reaches the rear detection position PB, in which the magnet 486 enters the detection range R2 of the second sensor 482. In the rear detection position PB, the output of a detection signal from the second sensor 482 changes from ON to OFF. The rear detection position PB is an example of the "rear brake position". The magnet 486 is detected when the output of a detection signal from the first sensor 481 or the second sensor 482 is ON, and the magnet 486 is not detected when the output of a detection signal from the first sensor 481 or the second sensor 482 is OFF. The state in which the output of a detection signal from the first sensor 481 or the second sensor 482 is ON is also referred to as a "detection state", and the state in which it is OFF is also referred to as a "non-detection state".

[0078] When the magnet 486 reaches the rear detection position PB and a detection signal is received by the second sensor 482, the motor control unit 562 initiates a braking action for the motor 2. The spindle shaft 46 moves backward until the motor 2 comes to a complete stop after braking begins. When the motor 2 stops completely, the magnet 486 stops at the stop position PE of the detection range R2. When the spindle shaft 46 is in the stop position PE, the second sensor 482 outputs a detection signal. Based on the detection result from the second sensor 482, the motor 2 is stopped, thus enabling the spindle shaft 46 to be detected in the rear detection position PB more easily than if its position were determined from the number of revolutions of the motor 2.

[0079] In this embodiment, the shaft position sensing element 564 determines the position of the spindle shaft 46 based on the number of revolutions of the motor 2 detected by the Hall sensor 203. The correlation between the number of revolutions of the motor 2 obtained by the shaft position sensing element 564 and the position of the magnet 486 is in the upper range of Fig. 8 shown. In the example shown in Fig. Figure 8 shows the cumulative number of revolutions in the normal direction of motor 2. Specifically, the cumulative number of revolutions of motor 2 increases as the spindle shaft 46 moves backward, while it decreases as the spindle shaft 46 moves forward.

[0080] In this embodiment, the shaft position detection part 564 is configured such that it starts counting the cumulative number of revolutions of the motor 2 from the time indicated by a position CD in the upper area of Fig. Figure 8 shows the situation when the spindle shaft 46 reaches the non-detection position PD and the output of the detection signal from the first sensor 481 changes from ON to OFF. This configuration reduces the influence of a deviation (change) in the initial position PS on counting the cumulative number of revolutions of the motor 2. This improves the accuracy in determining the position of the spindle shaft 46 compared to a case where the counting of the cumulative number of revolutions of the motor 2 is started from the initial position PS.

[0081] When the switch 152 is switched off by releasing the actuation of the push button 151, the spindle shaft 46 moves forward in the direction of the initial position PS, as indicated by an arrow DD in the upper area of Fig. Figure 8 shows that the forward movement of the spindle shaft 46 is also referred to as a "forward movement". The forward movement of the spindle shaft 46 can be initiated at any position between the initial position PS and the stop position PE.

[0082] A target speed (target rotational speed) V1 of the spindle shaft 46 during forward movement can be freely defined. In this embodiment, the target speed V1 is a maximum speed of the spindle shaft 46 that can be achieved by the motor 2. The target speed V1 is an example of the "first speed". When the spindle shaft 46 moves forward from the stop position PE, the magnet 486 is moved out of the detection range R2, and the output of the detection signal from the second sensor 482 changes from ON to OFF. As the spindle shaft 46 continues to move forward, the magnet 486 reaches a deceleration position P1.

[0083] The braking position P1 is located behind (on the rear side of) the initial position PS. The braking position P1 is predetermined, for example, based on the results of preliminary experiments, thus improving the positional accuracy of the spindle shaft 46, which stops at the initial position PS. The braking position P1 is set such that it is located, for example, 1.0 to 5.0 mm from a braking position P2 (described later) when the spindle shaft 46 begins its forward movement from the stop position PE.

[0084] In this embodiment, the braking position P1 is determined based on the cumulative number of revolutions of the motor 2. Thus, the shaft position sensing element 564 is configured to determine whether the magnet 486 has reached the braking position P1, based on the cumulative number of revolutions of the motor 2. This configuration can omit a sensing element for detecting the magnet 486 in the braking position P1 (eliminating the need for one) and can therefore avoid or reduce an increase in the number of parts of the fastening tool 1. Furthermore, the braking position P1 can be set and changed more easily than in a case where such a sensing element is provided.

[0085] In this embodiment, the braking position P1 is fixed at a position defined by a position point C1 in the upper area of Fig. Figure 8 shows that the cumulative number of revolutions of motor 2 reaches a predetermined cumulative number of revolutions TH after the spindle shaft 46 begins its forward movement. The cumulative number of revolutions TH of motor 2 during the forward movement of the spindle shaft 46 from the stop position PE, where the spindle shaft 46 starts its forward movement, to the braking position P1 is such that it is less than a predetermined number of revolutions THb than the cumulative number of revolutions THa of motor 2 during the reverse movement of the spindle shaft 46 from the non-detection position PD, where the counting of the cumulative number of revolutions of motor 2 starts, to the stop position PE.The braking position P1 is set such that it is located behind the non-detection position PD at a distance corresponding to the cumulative number of revolutions THb when the spindle shaft 46 starts the forward movement from the stop position PE.

[0086] The shaft position sensing element 564 starts counting the cumulative number of revolutions of motor 2 at the moment the spindle shaft 46 begins its forward movement. When the cumulative number of revolutions of motor 2 reaches the predetermined cumulative number of revolutions TH, the shaft position sensing element 564 determines that the spindle shaft 46 has reached the braking position P1.

[0087] When the spindle shaft 46 reaches the braking position P1, the motor control unit 562 controls the motor 2 to change the speed (rotational speed) of the spindle shaft 46 to a target speed (target rotational speed) V2, which is lower than the target speed V1. In this embodiment, the motor control unit 562 reduces the rotational speed of the motor 2 so that the movement speed of the spindle shaft 46 is reduced to approximately 50% of the target speed V1.

[0088] The target speed V2 is preferably set to be 50 to 70% of the target speed V1 to improve the accuracy of the spindle shaft 46's stop position. The target speed V2 is an example of a "second speed." In this embodiment, the motor control unit 562 reduces the number of revolutions per minute of the motor 2 by means of a PWM control to change the duty cycle output to the motor 2. The speed of the motor 2 is accurately changed by the PWM control, thus accurately changing the movement speed of the spindle shaft 46.

[0089] As the spindle shaft 46 moves further forward from the braking position P1, it reaches the braking position P2, at which the output of the detection signal from the first sensor 481 changes from OFF to ON. The braking position P2 essentially corresponds to the non-detection position PD. When the output of the detection signal from the first sensor 481 changes from OFF to ON, the shaft position detection element 564 determines that the spindle shaft 46 has reached the braking position P2.

[0090] When the spindle shaft 46 reaches the braking position P2, the motor control unit 562 controls the motor 2 to brake the spindle shaft 46. Even after the motor 2 is braked, the spindle shaft 46 continues to move forward until the motor 2 is completely stopped and stops in the initial position PS. In this embodiment, the motor control unit 562 is configured to stop the motor 2 by short-circuit braking when the terminals of the motor 2 are short-circuited. This configuration reduces the time required to stop the motor 2. Furthermore, it shortens the braking distance of the spindle shaft 46, thus reducing or preventing deviation in the stopping position of the spindle shaft 46. The short-circuit braking includes both three-phase and two-phase short-circuit braking.

[0091] A6. Drive control of motor 2: A flowchart of the drive control of motor 2 during a cycle of a fastening process of the fastener 9 is shown with reference to Fig. 9, Fig. 10 to Fig. 11 described. Fig. Figure 9 shows a (first) sequence that is started while the push button 151 is released and the spindle shaft 46 is in the initial position PS. In the following description, each "step" in the process (sequence) is abbreviated with "S".

[0092] In S10, the motor control unit 562 waits for the switch 152 to be activated by pressing the push button 151. When the switch 152 is activated by pressing the push button 151 (S10: YES), the motor control unit 562 switches the process to S20 and rotates the motor 2 in its normal direction, moving the spindle shaft 46 backward. The motor control unit 562 controls, for example, the speed of the reverse movement of the spindle shaft 46 to the target speed V1.

[0093] In S30, the shaft position sensing unit 564 monitors the output of the sensing signal from the first sensor 481. When the output of the sensing signal from the first sensor 481 changes from ON to OFF (S30: YES), the shaft position sensing unit 564 determines that the spindle shaft 46 has reached the non-sensing position PD and switches the process to S40. In S40, the shaft position sensing unit 564 begins counting the cumulative number of revolutions of motor 2.

[0094] In S50, the shaft position sensing unit 564 monitors the output of the sensing signal from the second sensor 482. If the output of the sensing signal from the second sensor 482 is OFF, the shaft position sensing unit 564 determines that the spindle shaft 46 has not reached the rear sensing position PB (S50: NO) and switches the process to S52. In S52, the motor control unit 562 monitors whether the switch 152 is turned off by a release operation on the push button 151. If the switch 152 is turned off (S52: YES), the motor control unit 562 switches the process to S60. If the switch 152 is not turned off within a certain time (S52: NO), the motor control unit 562 returns the process to S50.

[0095] In S50, when the output of the detection signal from the second sensor 482 changes from OFF to ON (S50: YES), the shaft position detection unit 564 determines that the spindle shaft 46 has reached the rear detection position PB. In S60, the motor control unit 562 executes a control to brake the motor 2. When the speed of the motor 2 becomes zero due to braking, the spindle shaft 46 stops at the stop position PE. In this embodiment, during the reverse movement of the spindle shaft 46, the motor control unit 562 brakes the motor 2 by stopping the excitation (power supply) of the motor 2 (by reducing the duty cycle (duty time) to zero). The motor control unit 562 can stop the motor 2 by short-circuit braking.

[0096] Fig. Figure 10 shows a (second) sequence that is started while the spindle shaft 46 is moved backwards during the pressing operation of the pusher 151, or is stopped at the stop position PE.

[0097] In S110, the motor control unit 562 waits for the switch 152 to be turned off by the release of the push button 151. When the switch 152 is turned off (S110: YES), the motor control unit 562 switches the process to S120 and rotates the motor 2 in reverse, moving the spindle shaft 46 forward. The motor control unit 562 controls the movement speed of the spindle shaft 46 to the target speed V1. In S130, the shaft position sensing unit 564 starts counting the cumulative number of revolutions of the motor 2. The processes of S120 and S130 can be executed in any order or simultaneously.

[0098] In S140, the shaft position sensing unit 564 determines whether the spindle shaft 46 has reached the braking position P1. Specifically, the shaft position sensing unit 564 monitors the cumulative number of revolutions of motor 2 and determines whether the result of the cumulative number of revolutions of motor 2, started in S130, reaches the cumulative number of revolutions TH. If the cumulative number of revolutions of motor 2 does not reach the cumulative number of revolutions TH (S140: NO), the shaft position sensing unit 564 switches the process to S142.

[0099] In S142, the shaft position sensing unit 564 monitors the output of the sensing signal from the first sensor 481 and determines whether the spindle shaft 46 has reached the braking position P2. For example, if the push button 151 is released before the spindle shaft 46 reaches the stop position PE during reverse movement, the spindle shaft 46 may reach the braking position P2 before the cumulative number of revolutions of the motor 2 reaches the cumulative number of revolutions TH.

[0100] If the output of the detection signal from the first sensor 481 is OFF (S142: NO), the shaft position detection unit 564 determines that the spindle shaft 46 has not reached the braking position P2 and returns the process to S140. If the output of the detection signal from the first sensor 481 changes from OFF to ON (S142: YES), the shaft position detection unit 564 determines that the spindle shaft 46 has reached the braking position P2 and switches the process to S170.

[0101] In S140, when the cumulative number of revolutions of motor 2 reaches the cumulative number of revolutions TH (S140: YES), the shaft position sensing unit 564 determines that the spindle shaft 46 has reached the braking position P1 and switches the process to S150. In S150, the motor control unit 562 starts reducing the speed of motor 2 to reduce the movement speed of the spindle shaft 46 from the target speed V1 to the target speed V2.

[0102] In S160, the spindle position sensing unit 564 monitors the output of the sensing signal from the first sensor 481 and determines whether the spindle shaft 46 has reached the braking position P2. If the spindle shaft 46 has not reached the braking position P2 (S160: NO), the spindle position sensing unit 564 repeats the process from S160. When the output of the sensing signal from the first sensor 481 changes from OFF to ON (S160: YES), the spindle position sensing unit 564 determines that the spindle shaft 46 has reached the braking position P2 and switches the process to S170. In S170, the motor control unit 562 brakes the motor 2 by means of a short-circuit braking action to stop the spindle shaft 46 and terminates the process.

[0103] Fig. Figure 11 is an example of the drive control of motor 2 when the spindle shaft 46 moves backward to the stop position PE and then forward from the stop position PE back to the initial position PS. At time t1, the switch 152 is turned on by the actuation of the push button 151. The motor control unit 562 drives the motor 2 to rotate in the normal direction, so that the movement speed of the spindle shaft 46 reaches the target speed V1. At time t2, the spindle shaft 46 reaches the non-detection position PD, and the detection signal from the first sensor 481 changes from ON to OFF. The shaft position detection unit 564 starts counting the cumulative number of revolutions of motor 2.

[0104] At time t3, the spindle shaft 46 reaches the rear detection position PB, and the detection signal from the second sensor 482 changes from OFF to ON. The motor control unit 562 brakes the motor 2. At time t4, the spindle shaft 46 stops at the stop position PE and ends its reverse movement.

[0105] At time t5, switch 152 is switched off by a release action on push button 151. The motor control unit 562 drives motor 2 to rotate in the reverse direction, so that the spindle shaft 46 reaches the target speed V1. The shaft position sensing unit 564 starts counting the cumulative number of revolutions of motor 2. At time t6, the cumulative number of revolutions of motor 2 reaches the cumulative number of revolutions TH, and the motor control unit 562 drives motor 2 to reduce the spindle shaft 46's speed to the target speed V2.

[0106] At time t7, the spindle shaft 46 reaches the braking position P2, and the detection signal from the first sensor 481 changes from OFF to ON. The motor control unit 562 brakes the motor 2 by means of a short-circuit braking action. At time t8, the spindle shaft 46 stops at the initial position PS and terminates its forward movement.

[0107] As described above, in the fastening tool 1 according to this embodiment, when the spindle shaft 46 moves forward and reaches the braking position P1, the movement speed of the spindle shaft 46 is reduced from the target speed V1 to the target speed V2 by a PWM control. The drive of the motor 2 is stopped after the movement speed of the spindle shaft 46 has been reduced, thus reducing or preventing a deviation in the stop position of the spindle shaft 46 when the spindle shaft 46 stops at the initial position PS during forward movement. This avoids or prevents the occurrence of a problem where the pin gripping part 165 cannot grip the pin 91 correctly.

[0108] In the fastening tool 1 of this embodiment, when the cumulative number of revolutions of the motor 2, obtained during the forward movement of the spindle shaft 46, reaches the cumulative number of revolutions TH, the shaft position sensing element 564 determines that the spindle shaft 46 has reached the braking position P1. Thus, the braking position P1 is detected with a small number of parts, without the need to provide a component for detecting the braking position P1. Furthermore, the braking position P1 can be easily set and changed. B. Second embodiment

[0109] As in Fig. As shown in Figure 12, the drive control of the motor 2 in the fastening tool 1 according to a second embodiment of the present disclosure differs from that of the first embodiment in that S144, S146, S148 and S152 are provided instead of S140, S142 and S150, and in all other respects the fastening tool 1 of the second embodiment has the same structure as that of the first embodiment. In this embodiment, the movement speed of the spindle shaft 46 is reduced at the time the target speed V1 is reached during the forward movement.

[0110] In S144, the motor control unit 562 monitors the cumulative number of revolutions of motor 2 and determines whether the movement speed of the spindle shaft 46 reaches the target speed V1. If the cumulative number of revolutions of motor 2 reaches a predetermined value and the movement speed of the spindle shaft 46 reaches the target speed V1 (S144: YES), the shaft position sensing unit 564 switches the process to S146.

[0111] In S146, the shaft position sensing element 564 calculates a distance from a position (also referred to as an "reach position") of the spindle shaft 46 at the time the target speed V1 is reached to the braking position P2. In this embodiment, the distance from the reach position to the braking position P2 is indicated by the cumulative number of revolutions of the motor 2 during the forward movement from the reach position to the braking position P2. In this embodiment, the counting of the cumulative number of revolutions of the motor 2 is started from the non-sensing position PD, which essentially corresponds to the braking position P2. Thus, the shaft position sensing element 564 obtains the distance (the cumulative number of revolutions of the motor 2) from the reach position to the braking position P2 by obtaining the cumulative number of revolutions of the motor 2 in the reach position.

[0112] In S148, the motor control unit 562 calculates a negative acceleration using the distance (the cumulative number of revolutions of the motor 2) from the approach position to the braking position P2. "Negative acceleration" means deceleration to slow down an object. In this embodiment, the motor control unit 562 calculates the negative acceleration as a fixed value, where the movement of the spindle shaft 46 is considered a linear movement with a constant negative acceleration. The speed of movement of the spindle shaft 46 is defined as the target speed V1 in the approach position and as the target speed V2 in the braking position P2. Calculating the acceleration as a fixed value reduces the computational effort.In S152, the motor control unit 562 drives the motor 2 according to the negative acceleration, which was calculated as a fixed value, and decelerates (reduces the speed of) the spindle shaft 46 until the spindle shaft 46 reaches the braking position P2. The acceleration is not limited to being constant, but can be variable.

[0113] As in Fig.As shown in Figure 13, at time t5, as in the first embodiment, when the push button 151 is released, the motor control unit 562 drives the motor 2 to rotate in the reverse direction so that the movement speed of the spindle shaft 46 reaches the target speed V1. When the movement speed of the spindle shaft 46 reaches the target speed V2 at time t6b, the shaft position sensing unit 564 detects the arrival position and calculates a distance (a cumulative number of revolutions TH2 of the motor 2) from the arrival position to the braking position P2. The motor control unit 562 calculates a negative acceleration dV using the cumulative number of revolutions TH2 of the motor 2 during the movement from the arrival position to the braking position P2. The motor control unit 562 drives the motor 2 with the negative acceleration dV to reduce the movement speed of the spindle shaft 46.

[0114] In the fastening tool 1 according to this embodiment, the motor control part 562 stops driving the motor 2 after the movement speed of the spindle shaft 46 has been reduced by the calculated negative acceleration dV. As in the first embodiment, driving the motor 2 is stopped after the movement speed of the spindle shaft 46 has been reduced, so that a deviation in the stop position of the spindle shaft 46 is reduced or prevented when the spindle shaft 46 moves forward and stops at the initial position PS.

[0115] In the fastening tool 1 according to this embodiment, the motor control unit 562 calculates the negative acceleration dV using the distance from the reach position to the braking position P2 and drives the motor 2 to reduce the movement speed of the spindle shaft 46 with the calculated negative acceleration dV. The negative acceleration is calculated according to the reach position. Therefore, even if, for example, the reach position varies due to differences in the timing of the release actuation of the push button 151, the movement speed in the braking position P2 is changed to the target speed V2. Thus, a deviation in the stopping position of the spindle shaft 46 due to a deviation in the reach position is reduced or prevented when the spindle shaft 46 stops at the initial position PS. C. Other embodiments

[0116] (C1) In the first embodiment described above, the braking position P1 is set at a position where the cumulative number of revolutions of the motor 2 reaches the predetermined cumulative number of revolutions TH after the start of the forward movement of the spindle shaft 46. However, the braking position P1 can be set behind the initial position PS at a predetermined distance (at a distance corresponding to a predetermined cumulative number of revolutions of the motor 2). In this case, the speed of movement of the spindle shaft 46 can be reduced at a certain position independently of the position at which the spindle shaft 46 starts the forward movement.

[0117] (C2) In the second embodiment described above, the motor control unit 562 changes the number of revolutions per unit of time of the motor 2 by means of a PWM control to change the duty cycle output to the motor 2. However, the motor control unit 562 can be configured to change the speed of movement of the spindle shaft 46 by means of a constant-speed rotary control of the motor 2. The “constant-speed rotary control” refers to a control for adjusting the drive voltage of the motor 2 such that the number of revolutions per unit of time of the motor shaft 25 reaches a predetermined target number of revolutions or less. The speed of movement of the spindle shaft 46 is accurately changed by a constant-speed rotary control. The motor control unit 562 can be configured to use a constant-speed rotary control of the motor 2 to control the target number of revolutions of the motor 2, for example.Perform 50 to 75% of the target number of revolutions of motor 2 during forward movement from the stop position PE to the initial position PS.

[0118] (C3) The structures of motor 2, transmission mechanism 3, and drive mechanism 4 can be suitably modified. For example, motor 2 can be a brushed motor or an AC (alternating current) motor. The number of planetary gear mechanisms of the planetary reduction gear 31 and the arrangement of the intermediate shaft 33 can be suitably modified. For example, in the drive mechanism 4, a feed screw mechanism comprising a nut having an internal thread on its inner circumference and a spindle shank having an external thread on its outer circumference, which engages directly with the nut, can be used instead of the ball screw mechanism 40, which comprises the nut 41 and the spindle shank 46, which engages with the nut 41 via the balls.The ball screw mechanism 40 can be configured such that the spindle shaft 46 is restricted in its movement in the forward-backward direction and is rotatably mounted, and the nut 41 moves in the forward-backward direction along with the rotation of the spindle shaft 46. In this case, the pin gripping part 165 is directly or indirectly connected to the nut 41.

[0119] (C4) In the embodiments described above, the first and second sensors 481, 482 are magnetic field detection sensors, but the sensors may be of a different type (e.g. an optical sensor, such as a light barrier) or mechanical switches.

[0120] (C5) In the embodiments described above, the controller 156 is a computer comprising a CPU, ROM, and RAM, but it can also be comprised of, for example, a programmable logic device such as an ASIC (Application Specific Integrated Circuit) and an FPGA (Field Programmable Gate Array). The CPU can execute a program stored in ROM to perform the drive control processes of the embodiments described above. In this case, the program can be pre-stored in the ROM of the controller 156, and if the controller 156 has non-volatile memory, the program can be stored in the non-volatile memory. Alternatively, the program can be stored in an external storage medium (e.g., a USB flash drive) that can read data.The drive control process of the embodiments and modifications described above can be distributed and executed across a variety of control circuits.

[0121] The present disclosure is not limited to one of the embodiments described above, but can be implemented by a multitude of configurations without deviating from the scope of the disclosure. For example, the technical features of each of the embodiments described above can be substituted or suitably combined to solve some or all of the problems described above or to achieve some or all of the advantageous effects described above. Any of the technical features can suitably be omitted, unless the technical feature is designated as essential in the present description. REFERENCE MARK LIST

[0122] 1: Fastening tool, 2: Motor, 3: Transmission mechanism, 4: Drive mechanism, 7: Collection container, 9: Fastener, 10: Housing, 11: Outer housing, 13: Inner housing, 15: Handle, 16: Nose, 20: Motor body, 21: Stator, 23: Rotor, 25: Motor shaft, 27: Fan wheel, 30: Reduction gear housing, 31: Planetary reduction gear, 33: Intermediate shaft, 35: Nut drive gear, 40: Ball screw mechanism, 41: Nut, 46: Spindle shaft, 47: Extension shaft, 48: Position sensing mechanism, 49: Connecting component, 70: Passage, 91: Pin, 95: Collar, 111: Roller guide, 113: Container connecting part, 114: Opening, 117: Guide sleeve, 150: Circuit board, 151: Push button, 152: Switch, 155: Control housing part, 156: Control, 157: Actuator part, 158: Battery mounting part, 159: Battery, 161: Anvil, 165: Pin gripper part, 201: Three-phase inverter, 203: Hall sensor, 205: Current sensing amplifier, 311: Sun gear, 313: Carrier, 411: Output gear,412: radial bearing, 460: drive shaft, 461: through hole, 463: roller holder, 464: roller, 481: first sensor, 482: second sensor, 585: magnet holder, 486: magnet, 560: CPU, 562: motor control unit, 564: shaft position sensing unit, 565: internal bus, 566: memory, 568: interface circuit, 911: shaft part, 913: small diameter part, A1: drive axis, A2: rotary axis, OD: external fixture, W1: workpiece, W2: workpiece QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2019 - 000 892 A

[0002]

Claims

[1] Fastening tool configured to fasten workpieces by means of a fastener comprising a pin and a cylindrical part, with an engine that has a motor shaft, a housing that accommodates the motor, a pen gripping part configured to grip the pen, a drive mechanism connected to the pin gripping part and configured to perform a reverse movement to move backward from an initial position along a drive axis defining a front-back direction of the fastening tool by a normal rotation of the motor shaft, and to perform a forward movement to move forward to the initial position along the drive axis by a reverse rotation of the motor shaft, a position sensing component configured to obtain a relative position of the drive mechanism in the front-back direction relative to the housing, and a motor control unit configured to execute the drive control of the motor to change the direction and speed of movement of the drive mechanism, in which the engine control unit the forward movement of the drive mechanism starts, so that the speed of movement reaches an initial speed, The movement speed is reduced to a second speed, which is lower than the first speed, by means of a PWM control to change a duty cycle output to the motor when the obtained relative position reaches a deceleration position behind the initial position during forward movement, and The motor stops driving when the obtained relative position reaches a predetermined braking position in front of the braking position and behind the initial position. [2] Fastening tool configured to fasten workpieces by means of a fastener comprising a pin and a cylindrical part, with an engine that has a motor shaft, a housing that accommodates the motor, a pen gripping part configured to grip the pen, a drive mechanism connected to the pin gripping part and configured to perform a reverse movement to move backward from an initial position along a drive axis defining a front-back direction of the fastening tool by a normal rotation of the motor shaft, and to perform a forward movement to move forward to the initial position along the drive axis by a reverse rotation of the motor shaft, a position sensing component configured to obtain a relative position of the drive mechanism in the front-back direction relative to the housing, and a motor control unit configured to execute the drive control of the motor to change the direction and speed of movement of the drive mechanism, in which the engine control unit the forward movement of the drive mechanism starts, so that the speed of movement reaches an initial speed, The speed of movement is reduced to a second speed, which is lower than the first speed, by a constant-speed rotary control for setting a drive voltage of the motor, so that a number of revolutions per minute of the motor shaft reaches a predetermined target number of revolutions, when the obtained relative position reaches a braking position backward from the initial position during forward movement, and The motor stops driving when the obtained relative position reaches a predetermined braking position in front of the braking position and behind the initial position. [3] Fastening tool configured to fasten workpieces by means of a fastener comprising a pin and a cylindrical part, with an engine that has a motor shaft, a housing that accommodates the motor, a pen gripping part configured to grip the pen, a drive mechanism connected to the pin gripping part and configured to perform a reverse movement to move backward from an initial position along a drive axis defining a front-back direction of the fastening tool by a normal rotation of the motor shaft, and to perform a forward movement to move forward to the initial position along the drive axis by a reverse rotation of the motor shaft, a position sensing component configured to obtain a relative position of the drive mechanism in the front-back direction relative to the housing, and a motor control unit configured to execute the drive control of the motor to change the direction and speed of movement of the drive mechanism, in which the engine control unit the forward movement of the drive mechanism starts, so that the speed of movement reaches an initial speed, a negative acceleration is determined such that the speed of movement is reduced to a second speed, which is lower than the first speed, in a braking position located at a predetermined distance behind the initial position, and the speed of movement is reduced with the determined negative acceleration when the speed of movement reaches the first speed during forward movement, and The motor stops driving when the obtained relative position reaches the braking position. [4] Fastening tool according to claim 1 or 2, wherein the position sensing part receives a cumulative number of revolutions of the motor shaft and obtains the relative position using the obtained cumulative number of revolutions of the motor shaft. [5] Fastening tool according to claim 4, wherein when the cumulative number of revolutions obtained during the forward movement reaches a predetermined cumulative number of revolutions, the position sensing part determines that the obtained relative position of the drive mechanism reaches the braking position. [6] Fastening tool according to claim 4, wherein the cumulative number of revolutions of the motor shaft during forward movement from a starting position of the forward movement to the braking position is less by a predetermined number of revolutions than the cumulative number of revolutions of the motor shaft during reverse movement from a starting position of the counting of the cumulative number of revolutions of the motor shaft during reverse movement to the starting position of the forward movement. [7] Fastening tool according to claim 3, wherein the position detection part a cumulative number of motor shaft revolutions is obtained and an achievement position is obtained at which the movement speed reaches the first speed, using the obtained cumulative number of motor shaft revolutions, and a distance is calculated from the achieved target position to the braking position, and The motor control unit calculates the negative acceleration using the calculated distance from the reaching position to the braking position and reduces the movement speed with the calculated negative acceleration. [8] Fastening tool according to claim 7, wherein the motor control part reduces the speed of movement with a constant negative acceleration corresponding to the distance from the achieved reach position to the braking position. [9] Fastening tool according to any one of claims 4 to 8, further comprising a captured object that is provided for in the drive mechanism and moves integrally with the drive mechanism, and a brake position detection component configured to detect the detected object when the drive mechanism is in the brake position, in which the position detection part starts detecting the cumulative number of revolutions of the motor shaft at a time when a detection result of the brake position detection part changes during the reverse movement from a detection state in which the detected object is detected to a non-detection state in which the detected object is not detected. [10] Fastening tool according to claim 3 or one of claims 7 to 9, which is directly or indirectly dependent on claim 3, wherein the motor control part changes the speed of movement by means of a PWM control to change a duty cycle output to the motor. [11] Fastening tool according to claim 3 or one of claims 7 to 9, which is directly or indirectly dependent on claim 3, in the motor control part a constant-speed rotary control is used to adjust the drive voltage of the motor so that a predetermined target number of revolutions per unit of time of the motor shaft is achieved, and changes the speed of movement by changing the target number of revolutions. [12] Fastening tool according to any one of claims 1 to 11, wherein the motor control part stops the motor by short-circuit braking by short-circuiting the terminals of the motor. [13] Fastening tool according to any one of claims 1 to 12, wherein the drive mechanism a nut that is driven by the motor to rotate around the drive shaft, and a shaft connected to the pin gripping part and configured to perform the reverse movement by a normal rotation of the motor shaft, and to perform the forward movement by a reverse rotation of the motor shaft. [14] Fastening tool according to any one of claims 1 to 13, further comprising a captured object that is provided for in the drive mechanism and moves integrally with the drive mechanism, and a detection element for a rear brake position, configured to detect the detected object when the drive mechanism is in a rear brake position, behind the brake position, where the motor control unit stops driving the motor when the detected object is detected by the detection unit for a rear brake position. [15] Fastening tool according to any one of claims 1 to 14, further comprising a button that is configured to be pressed or released by a user, in which the motor control part drives the motor to rotate the motor shaft in a normal direction when the push button is pressed, while it drives the motor to rotate the motor shaft in a reverse direction when the push button is released.

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