JP2019013990A - Impact rotary tool - Google Patents

Abstract

To provide a technique for estimating a fastening torque with a high accuracy.SOLUTION: An impact rotary tool 1 comprises: a rotation angle acquisition part 20 which acquires an output shaft rotation angle due to one-time impact of an impact mechanism 9; an energy calculation part 22 which calculates an impact energy which is added to an output shaft 8 by one-time impact of the impact mechanism 9; a fastening torque calculation part 23 which calculates a fastening torque on the basis of the impact energy calculated by the energy calculation part 22 and the output shaft rotation angle acquired by the rotation angle acquisition part 20; and a motor control part 24 which stops rotation of a motor on the basis of the calculated fastening torque. The fastening torque calculation part 23 calculates a fastening torque by use of a value in which cumulative energy, in which impact energy calculated for each impact is integrated, is divided by cumulative rotation angle in which an output shaft rotation angle acquired for each impact is integrated.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an impact rotary tool for tightening screw members such as bolts and nuts by intermittent rotational impact force.

  In a mechanical impact rotary tool, a hammer rotating with a motor output strikes an anvil in a rotation direction to generate an intermittent rotational impact force on an output shaft, thereby tightening a screw member. In addition, an oil pulse tool, which is a kind of impact rotary tool, causes an intermittent rotational impact force to be generated on an output shaft by a liner that rotates with motor output creating a pressure difference between oil chambers, thereby tightening a screw member. Since the impact rotary tool is used in an assembly factory or the like, the tightening torque of the screw member needs to be accurately controlled so as to be a value set by the user.

  In order to increase the control accuracy of the tightening torque, it is preferable to provide a torque measuring means on the output shaft and directly measure the actual tightening torque. However, there is a problem that the cost and size of the tool are increased. Therefore, conventionally, an impact rotary tool having a shut-off function for automatically stopping the motor by estimating that the tightening torque has reached a set value has been provided. Patent Document 1 calculates a tightening torque by calculating means for calculating impact energy applied to an output shaft, means for calculating a rotation angle of the output shaft between impacts, and dividing the impact energy by a rotation angle between impacts. An impact rotary tool comprising means and means for stopping the rotation drive unit when the calculated tightening torque exceeds a specified value is disclosed. The impact rotary tool disclosed in Patent Document 1 calculates a tightening torque T (= E / θ) using the impact energy E and the output shaft rotation angle θ between impacts, and torque-controls the calculated tightening torque T. It is used for.

JP 2000-354976 A

  In the impact rotary tool, when the tightening torque increases due to repeated hitting, the output shaft rotation angle θ between hits decreases. Therefore, according to the calculation method of the tightening torque T according to Patent Document 1, the calculated value of the tightening torque T (= E / θ) is influenced by the detection error of the rotation angle θ in the high torque region where the rotation angle θ is very small. There is a problem that the tightening torque T cannot be accurately estimated. Therefore, a technique for estimating the tightening torque T with high accuracy and increasing the control accuracy of the tightening torque is desired.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for estimating the tightening torque with high accuracy and increasing the control accuracy of the tightening torque.

  In order to solve the above-described problems, an impact rotary tool according to an aspect of the present invention detects an impact applied to an output shaft by an impact mechanism that generates an intermittent rotational impact force on the output shaft by a motor output, and an impact mechanism. An impact detection unit that performs the operation, a rotation angle acquisition unit that acquires an output shaft rotation angle due to a single impact of the impact mechanism, and an energy calculation unit that calculates impact energy applied to the output shaft by a single impact of the impact mechanism. A tightening torque calculation unit that calculates the tightening torque based on the impact energy calculated by the energy calculation unit and the output shaft rotation angle acquired by the rotation angle acquisition unit, and stops the rotation of the motor based on the calculated tightening torque. A tightening torque calculator that integrates impact energy calculated for each impact. Formic and using a value obtained by dividing the cumulative rotation angle by integrating the output shaft rotation angle acquired for each impact, it calculates a tightening torque.

  According to the present invention, it is possible to provide a technique for estimating the tightening torque with high accuracy and increasing the control accuracy of the tightening torque.

It is a figure which shows the structure of the impact rotary tool which concerns on embodiment. (A)-(c) is a figure which shows a mode that a hammer applies the hit | damage of a rotation direction to an anvil. It is a figure which shows the relationship between the actual torque for every impact number in embodiment, and the calculated tightening torque. It is a figure which shows the relationship between the actual torque for every number of impacts, and the estimated torque calculated by a comparison method. It is a figure which shows the correspondence of the target torque value memorize | stored in the shut-off impact number memory | storage part, and the number of shut-off impacts.

  FIG. 1 shows a configuration of an impact rotary tool according to an embodiment of the present invention. In the impact rotary tool 1, electric power is supplied by a rechargeable battery built in the battery pack. The motor 2 as a driving source is driven by the motor driving unit 11, and the rotation output of the motor 2 is decelerated by the speed reducer 3 and transmitted to the drive shaft 5. A hammer 6 is connected to the drive shaft 5 via a cam mechanism (not shown), and the hammer 6 is urged toward the anvil 7 including the output shaft 8 by the spring 4.

  While a load of a predetermined value or more does not act between the hammer 6 and the anvil 7, the hammer 6 and the anvil 7 are engaged in the rotation direction, and the hammer 6 transmits the rotation of the drive shaft 5 to the anvil 7. However, when a load of a predetermined value or more is applied between the hammer 6 and the anvil 7, the hammer 6 moves backward against the spring 4 by the cam mechanism, and the engagement state between the hammer 6 and the anvil 7 is released. Thereafter, the hammer 6 advances while rotating by an urging force by the spring 4 and a guidance by the cam mechanism, and strikes the anvil 7 in the rotational direction. In the impact rotary tool 1, the spring 4, the drive shaft 5, the hammer 6, and the cam mechanism apply a striking impact to the anvil 7 and the output shaft 8 by the motor output, and apply an intermittent rotational impact force to the anvil 7 and the output shaft 8. The impact mechanism 9 to be generated is configured.

  In the impact rotary tool 1, the configuration of the control unit 10, the setting unit 15 and the like is realized by a microcomputer or the like mounted on the control board. The control unit 10 includes a rotation angle acquisition unit 20, a rotation speed acquisition unit 21, an energy calculation unit 22, a tightening torque calculation unit 23, and a motor control unit 24, calculates the tightening torque, and calculates the calculated tightening torque. The motor 2 has a function of controlling the rotation of the motor 2 based on the above.

  The operation switch 16 is a trigger switch operated by a user, and the motor control unit 24 controls on / off of the motor 2 by operating the operation switch 16 and drives a motor according to the operation amount of the operation switch 16. To the unit 11. The motor drive unit 11 controls the voltage applied to the motor 2 according to the drive instruction supplied from the motor control unit 24 to adjust the motor rotation speed.

  The impact detection unit 12 detects an impact applied to the anvil 7 by the impact mechanism 9. For example, the impact detection unit 12 may include an impact sensor that detects an impact caused by the hammer 6 hitting the anvil 7, and an amplifier that amplifies the output of the impact sensor and supplies the amplified output to the control unit 10. For example, the impact sensor is a piezoelectric shock sensor and outputs a voltage signal corresponding to the impact, and the amplifier amplifies the output voltage signal and supplies the amplified voltage signal to the control unit 10. The impact detection unit 12 may adopt another configuration, and may be a sound sensor that detects an impact applied to the anvil 7 by the impact mechanism 9 by detecting an impact sound, for example.

  The rotation angle detector 18 detects the rotation angle of the motor 2 and / or the output shaft 8. In the embodiment, the rotation angle detection unit 18 may be a magnetic rotary encoder that detects the rotation angle of the motor 2. The rotation angle detection unit 18 supplies a motor rotation angle detection signal to the rotation angle acquisition unit 20. In the embodiment, the rotation angle acquisition unit 20 has a function of acquiring the rotation angle of the output shaft 8 from the motor rotation angle detection signal. Here, the rotation angle acquisition unit 20 acquires the angle at which the output shaft 8 rotates for each impact by the impact mechanism 9. Hereinafter, the angle at which the output shaft 8 rotates by a single impact is simply referred to as “output shaft rotation angle”.

  FIG. 2A to FIG. 2C show how the hammer 6 strikes the anvil 7 in the rotational direction. The hammer 6 has a pair of hammer claws 6a and 6b erected from the front surface, and the anvil 7 has a pair of anvil claws 7a and 7b extending in the radial direction from the center. The anvil 7 is integral with the output shaft 8, and the output shaft 8 rotates together with the anvil 7.

FIG. 2A shows a state in which the hammer claw and the anvil claw are engaged in the circumferential direction. The hammer claw 6a and the hammer claw 6b engage with the anvil claw 7a and the anvil claw 7b, respectively, and apply a rotational force in the direction indicated by the arrow A.
FIG. 2B shows a state in which the engagement state between the hammer claw and the anvil claw is released. When a load of a predetermined value or more is applied between the hammer 6 and the anvil 7 in the engaged state, the hammer 6 is retracted by a cam mechanism (not shown), the engagement state between the hammer pawl 6a and the anvil pawl 7a, and the hammer The engaged state between the claw 6b and the anvil claw 7b is released.
FIG. 2C shows a state in which the hammer claw hits the anvil claw and rotates the anvil 7. When the engagement state between the hammer claws 6a and 6b and the anvil claws 7a and 7b is released, the hammer 6 advances while rotating in the direction indicated by the arrow A, and the hammer claws 6a and 6b are respectively moved to the anvil claws. 7b, hitting the anvil claw 7a. By this impact, the anvil 7 rotates by an angle θ formed by l1 and l2, and the rotation angle of the hammer 6 becomes (π + θ) at this time.

The rotation angle acquisition unit 20 acquires the output shaft rotation angle θ per impact using the detection result by the impact detection unit 12 and the detection result by the rotation angle detection unit 18. Specifically, the rotation angle acquisition unit 20 acquires the output shaft rotation angle θ due to one impact from the motor rotation angle φ between impacts using the following (Equation 1). When the impact detection unit 12 detects an impact by the impact mechanism 9, the rotation angle acquisition unit 20 derives the output shaft rotation angle θ between the impacts from the motor rotation angle detection signal at the timing when the impact is detected.
θ = (φ / η) −π (Formula 1)
Here, η indicates a reduction ratio by the reduction gear 3.
Each time the hammer 6 strikes the anvil 7, the tightening torque of the screw member increases, so that the output shaft rotation angle θ acquired for each impact after the screw member is seated tends to gradually decrease.

  In the embodiment, the rotation angle acquisition unit 20 acquires the output shaft rotation angle θ from the motor rotation angle detection signal. However, in another example, the rotation angle detection unit 18 directly detects the rotation angle θ of the anvil 7. Also good. At this time, the rotation angle acquisition unit 20 can acquire the output shaft rotation angle θ between impacts based on the anvil rotation angle detection signal supplied from the rotation angle detection unit 18.

The rotational speed acquisition unit 21 acquires the impact speed ω between impacts using the detection result by the impact detection unit 12, the detection result by the rotation angle detection unit 18, and information from a timer (not shown). The rotational speed acquisition unit 21 specifies the time between impacts from the timer output, and calculates the impact speed ω. When the inertia moment of the anvil 7 and the output shaft 8 is J, the energy calculation unit 22 is applied to the anvil 7 and the output shaft 8 by one impact of the impact mechanism 9 using the following (Equation 2). Impact energy E is calculated.
E = (1/2) × J × ω ² (Expression 2)

  In the embodiment, the tightening torque calculation unit 23 calculates the tightening torque T based on the impact energy E calculated by the energy calculation unit 22 and the output shaft rotation angle θ acquired by the rotation angle acquisition unit 20.

The tightening torque calculation unit 23 of the embodiment integrates an integrated energy (ΣE) obtained by integrating the impact energy E calculated for each impact, and an integrated rotation angle (Σθ) obtained by integrating the output shaft rotation angle θ obtained for each impact. The tightening torque T is calculated using the value divided by. In the embodiment, a value obtained by dividing the accumulated energy (ΣE) by the accumulated rotation angle (Σθ) is calculated as the tightening torque T.
T = ΣE / Σθ (Formula 3)
Since the rotation angle θ and the striking speed ω may not be acquired stably during the first to several shocks, the tightening torque calculation unit 23 performs the nth (n is an integer of 2 or more) and subsequent times. The tightening torque T may be calculated by integrating the rotation angle θ and the impact energy E from the impact.

  FIG. 3 shows the relationship between the actual torque for each number of impacts and the tightening torque (estimated torque) calculated by the tightening torque calculator 23. FIG. 3 shows that the tightening torque can be estimated with high accuracy by the tightening torque calculating unit 23 calculating the tightening torque T by (Equation 3).

Hereinafter, a method for calculating an estimated torque in Patent Document 1 will be shown as a comparative example. In Patent Document 1, the estimated torque Tcom is calculated by the following (Equation 4).
Tcom = E / θ (Formula 4)
FIG. 4 shows, as a comparative example, the relationship between the actual torque for each number of impacts and the estimated torque calculated by the comparison method. According to (Expression 4), the calculated value of the estimated torque Tcom is greatly affected by the detection error of the rotation angle θ in the high torque region where the rotation angle θ is small. Therefore, as shown in FIG. 4, according to the calculation method of the comparative example, the estimated torque Tcom largely fluctuates.

  On the other hand, the tightening torque calculation unit 23 of the embodiment calculates the tightening torque T using the accumulated energy (ΣE) and the accumulated rotation angle (Σθ), so that the detection error for each impact is the estimated accuracy of the tightening torque. The impact on the environment is reduced. The motor control unit 24 stops the rotation of the motor 2 based on the high-precision tightening torque T calculated by the tightening torque calculation unit 23, thereby improving the control accuracy of the tightening torque. An embodiment of automatic stop control of the motor 2 will be described below.

Example 1
The user sets a target tightening torque value (hereinafter, also simply referred to as “target torque value”) corresponding to the work target to the impact rotary tool 1 before starting the work. During the tightening operation, the impact rotary tool 1 counts the number of impacts detected by the impact detection unit 12, and when the counted number of impacts reaches the number of impacts (shutoff impact number) corresponding to the target torque value, Executes a shut-off function that automatically stops rotation.

  The shut-off impact number storage unit 17 of the first embodiment stores the number of impacts (shut-off impact number) from when the impact by the impact mechanism 9 is started until the tightening torque reaches the target torque value. The shut-off impact number storage unit 17 stores a shut-off impact number corresponding to each set value of, for example, 30 steps. This means that the user can select one of the 30-step tightening torque values according to the work target. The shut-off impact number storage unit 17 may be configured as a master table, and the stored content may not be updated. The setting unit 15 refers to the stored contents of the shut-off impact number storage unit 17 and sets the shut-off impact number of the impact mechanism 9 in the control unit 10.

  FIG. 5 shows the correspondence between the target torque value stored in the shut-off impact number storage unit 17 and the shut-off impact number. For example, when the target torque value is set to 50 [Nm], the setting unit 15 refers to the storage content of the shut-off impact number storage unit 17 and sets the shut-off impact number to “55 times”.

  The shut-off impact number storage unit 17 only needs to store information or data for the setting unit 15 to derive the shut-off impact number corresponding to the target torque value. For example, the shut-off impact number is calculated from the target torque value. You may memorize | store the calculation formula for calculating | requiring and calculating. Conventionally, it is known that the tightening torque by the impact rotary tool is proportional to the square root of the number of hits. Therefore, the manufacturer of the impact rotary tool 1 measures the number of shutoff impacts for realizing a plurality of tightening torque values using a predetermined screw member and a fastened member, and a torque coefficient that is a proportional constant in the calculation formula k may be obtained and stored in the shut-off impact number storage unit 17.

  The accepting unit 14 accepts an operation input by the user and supplies it to the setting unit 15. The reception unit 14 includes a wireless communication module, and the user inputs an operation to the impact rotary tool 1 using a remote controller attached to the tool. The tool body may be provided with operation buttons and a touch panel, and the receiving unit 14 may receive an operation input by the user.

  Before starting the work, the user selects a target torque value using the remote controller. When the accepting unit 14 accepts the selection input of the target torque value, the setting unit 15 refers to the stored contents of the shut-off impact number storage unit 17 to derive the shut-off impact number corresponding to the target torque value, and the control unit 10 To supply. In the first embodiment, the setting unit 15 derives the shut-off impact number and supplies it to the control unit 10, and the control unit 10 makes the shut-off impact number available for rotation control of the motor 2. This is called number setting processing.

  During the operation, the control unit 10 monitors the output voltage of the impact detection unit 12, and if the output voltage of the impact detection unit 12 exceeds the impact determination voltage Vth, an intermittent rotational impact force is applied to the output shaft 8 by the impact mechanism 9. Determine that has occurred. The control unit 10 includes a comparator that compares the output voltage of the impact detection unit 12 and the impact determination voltage Vth, and may determine from the output of the comparator that an intermittent rotational impact force has occurred on the output shaft 8. .

  The motor control unit 24 counts the number of impacts detected by the impact detection unit 12. The motor control unit 24 automatically stops the rotation of the motor 2 when the counted number of impacts becomes the number of shut-off impacts. At this time, the tightening torque value of the screw member needs to be a target torque value set by the user.

  Depending on the screw member and the fastening member to be worked, before the screw member sits on the fastening member, a load of a predetermined value or more (hereinafter also referred to as “intermediate load”) is applied between the hammer 6 and the anvil 7. As a result, the hammer 6 may hit the anvil 7. In this case, when the motor control unit 24 stops the rotation of the motor 2 with the number of shut-off impacts, the number of impacts (impacts) is digested by an intermediate load. Does not reach the set target torque value. Therefore, the motor control unit 24 according to the first embodiment has a function of correcting the number of shut-off shocks set by the setting unit 15 when a load occurs midway.

  Returning to FIG. 1, the reference impact number storage unit 19 stores the number of impacts from when the impact by the impact mechanism 9 is started until the tightening torque reaches a predetermined torque value smaller than the target torque value. The reference impact number storage unit 19 may be replaced by the shut-off impact number storage unit 17. FIG. 5 shows the stored contents of the shut-off impact number storage unit 17, but the shut-off impact number storage unit 17 does not reach the torque value smaller than the target torque value (50 [Nm]) set by the user. I remember the number of shocks. In this sense, the reference impact number storage unit 19 may be substituted by the shut-off impact number storage unit 17. In the example shown in FIG. 5, the number of impacts until reaching 30 [Nm] is stored as “14 times”.

  The motor control unit 24 counts the impact detected by the impact detection unit 12, and the number of impacts when the tightening torque calculated by the tightening torque calculation unit 23 reaches a predetermined torque value (30 [Nm]). From the relationship between M and the number of impacts stored in the reference impact number storage unit 19 (14 times), the number of shutoff impacts (55 times) set by the setting unit 15 is corrected. Specifically, the motor control unit 24 stores the impact number M when the tightening torque calculated by the tightening torque calculation unit 23 reaches a predetermined torque value (30 [Nm]) and the reference impact number storage unit 19. The difference between the calculated number of impacts (14 times) is added to the number of shut-off impacts (55 times) set by the setting unit 15, and when the counted number of impacts becomes the number of shut-off impacts obtained by adding the difference, the motor The rotation of 2 is stopped.

  For example, when the number of impacts M when the tightening torque calculated by the tightening torque calculating unit 23 reaches a predetermined torque value (30 [Nm]) is “20 times”, the motor control unit 24 If there is not, it is recognized that an extra six shocks are required for the torque value reached in 14 shocks. Therefore, the motor control unit 24 adds “6 times” to the number of shut-off impacts (55 times) set by the setting unit 15 to correct the number of shut-off impacts to “61 times”. Thus, in the first embodiment, the motor control unit 24 improves the torque control accuracy by stopping the rotation of the motor 2 based on the tightening torque estimated with high accuracy.

(Example 2)
In the first embodiment, the shut-off impact number storage unit 17 stores the number of impacts (shut-off impact number) from when the impact by the impact mechanism 9 is started until the tightening torque reaches the target torque value. On the other hand, in the second embodiment, the shut-off impact number storage unit 17 stores the number of impacts (shut-off impact number) from when the tightening torque reaches the predetermined torque value until it reaches the target torque value. .

  For example, in FIG. 5, the number of impacts from reaching a predetermined torque value of 30 [Nm] to reaching a target torque value of 50 [Nm] is 41 times (= 55 times-14 times). The shut-off impact number storage unit 17 of the second embodiment stores the number of impacts from reaching a predetermined torque value to reaching the target torque value for each target torque value. Here, the predetermined torque value is preferably set as a torque value when the screw member is seated or after being seated so that the midway load does not affect the number of shut-off impacts in the second embodiment.

  In the second embodiment, the setting unit 15 sets, in the control unit 10, the number of shut-off impacts from when the tightening torque reaches a predetermined torque value until it reaches the target torque value. When the tightening torque calculated by the tightening torque calculating unit 23 reaches a predetermined torque value, the motor control unit 24 counts the impact detected by the impact detecting unit 12, and the counted number of impacts is the shut-off impact number. Then, the rotation of the motor 2 is stopped. The motor control unit 24 performs the automatic stop control of the motor 2 based on the tightening torque estimated with high accuracy by the tightening torque calculation unit 23, thereby realizing accurate tightening torque control.

  In the above, this invention was demonstrated based on embodiment and an Example. It is understood by those skilled in the art that the embodiments and examples are exemplifications, and that various modifications can be made to the respective components or combinations of the respective treatment processes, and such modifications are also within the scope of the present invention. It is a place.

  In the first and second embodiments, torque control is performed using the number of shut-off impacts. However, in a modified example, the motor control unit is utilized by using the fact that the tightening torque calculating unit 23 can accurately calculate the tightening torque. 24 may stop the rotation of the motor 2 when the tightening torque calculated by the tightening torque calculating unit 23 reaches the target torque value. That is, the motor control unit 24 may stop the rotation of the motor 2 when the tightening torque calculated by the tightening torque calculating unit 23 reaches the target torque value.

  Although the impact rotary tool 1 of the embodiment is equipped with a motor 2 that is an electric motor as a drive source, other types of motors such as an air motor may be mounted. The impact rotary tool 1 of the embodiment is a mechanical rotary tool, but may be another type of impact rotary tool, for example, an oil pulse tool.

The outline of the embodiment of the present invention is as follows.
An impact rotary tool (1) according to an aspect of the present invention includes an impact mechanism (9) that generates an intermittent rotational impact force on an output shaft (8) by a motor output, and an impact applied to the output shaft by the impact mechanism. Impact detection unit (12) to detect, rotation angle acquisition unit (20) to acquire the output shaft rotation angle by one impact of the impact mechanism, and impact energy applied to the output shaft by one impact of the impact mechanism An energy calculation unit (22) for calculating the torque, a tightening torque calculation unit (23) for calculating a tightening torque based on the impact energy calculated by the energy calculation unit and the output shaft rotation angle acquired by the rotation angle acquisition unit, A motor control unit (24) for stopping the rotation of the motor based on the calculated tightening torque. The tightening torque calculator (23) uses a value obtained by dividing the integrated energy obtained by integrating the impact energy calculated for each impact by the integrated rotational angle obtained by integrating the output shaft rotational angle obtained for each impact. Calculate the attached torque.

  The impact rotary tool (1) may further include a setting unit (15) for setting the number of shutoff impacts from when the tightening torque reaches a predetermined torque value until the target torque value is reached. When the tightening torque calculated by the tightening torque calculation unit (23) reaches a predetermined torque value, the motor control unit (24) counts the impact detected by the impact detection unit (12), and counts the impact When the number reaches the shut-off impact number, the rotation of the motor (2) may be stopped.

  The motor control unit (24) may stop the rotation of the motor when the tightening torque calculated by the tightening torque calculation unit (23) reaches the target torque value.

  The impact rotary tool (1) has a setting unit (15) for setting the number of shutoff impacts from when the impact by the impact mechanism is started until the tightening torque reaches the target torque value, and when the impact by the impact mechanism is started. A reference impact number storage unit (19) for storing the number of impacts until the tightening torque reaches a predetermined torque value smaller than the target torque value, and the motor control unit (24) includes an impact detection unit ( The impact detected in 12) is counted, and the number of impacts when the tightening torque calculated by the tightening torque calculation unit (23) reaches a predetermined torque value and stored in the reference impact number storage unit (19). It is preferable to correct the shut-off impact number set by the setting unit (15) from the relationship with the impact number set. The motor control unit (24) sets a difference between the number of impacts when the tightening torque calculated by the tightening torque calculation unit reaches a predetermined torque value and the number of impacts stored in the reference impact number storage unit. The rotation of the motor may be stopped when the counted number of impacts becomes the number of shut-off impacts obtained by adding the difference.

DESCRIPTION OF SYMBOLS 1 ... Impact rotary tool, 2 ... Motor, 8 ... Output shaft, 9 ... Impact mechanism, 10 ... Control part, 11 ... Motor drive part, 12 ... Impact detection part , 14... Accepting unit, 15... Setting unit, 16... Operation switch, 17... Shut-off impact number storage unit, 18. , 20... Rotation angle acquisition unit, 21... Rotation speed acquisition unit, 22... Energy calculation unit, 23... Tightening torque calculation unit, and 24.

Claims (5)

An impact mechanism that generates intermittent rotational impact force on the output shaft by motor output, an impact detection unit that detects an impact applied to the output shaft by the impact mechanism, and output shaft rotation by one impact of the impact mechanism A rotation angle acquisition unit that acquires an angle; an energy calculation unit that calculates impact energy applied to the output shaft by a single impact of the impact mechanism; the impact energy calculated by the energy calculation unit and the rotation angle acquisition unit The impact rotating tool includes a tightening torque calculating unit that calculates a tightening torque based on the acquired output shaft rotation angle, and a motor control unit that stops the rotation of the motor based on the calculated tightening torque. And
The tightening torque calculation unit uses the value obtained by dividing the accumulated energy obtained by integrating the impact energy calculated for each impact by the accumulated rotation angle obtained by integrating the output shaft rotation angle obtained for each impact, to determine the tightening torque. To calculate,
An impact rotary tool characterized by that. A setting unit for setting the number of shut-off impacts from when the tightening torque reaches a predetermined torque value until reaching the target torque value;
When the tightening torque calculated by the tightening torque calculation unit reaches a predetermined torque value, the motor control unit counts the impact detected by the impact detection unit, and the counted number of impacts is the number of shut-off impacts. The motor will stop rotating,
The impact rotary tool according to claim 1. The motor control unit stops the rotation of the motor when the tightening torque calculated by the tightening torque calculation unit reaches a target torque value.
The impact rotary tool according to claim 1. A setting unit for setting the number of shut-off impacts from when the impact by the impact mechanism is started until the tightening torque reaches the target torque value, and the tightening torque after the impact by the impact mechanism is started from the target torque value A reference impact number storage unit that stores the number of impacts until reaching a predetermined torque value that is smaller than
The motor control unit counts the impact detected by the impact detection unit, the number of impacts when the tightening torque calculated by the tightening torque calculation unit reaches a predetermined torque value, and the reference number of impacts From the relationship with the number of impacts stored in the storage unit, the shut-off impact number set by the setting unit is corrected.
The impact rotary tool according to claim 1. The motor control unit calculates a difference between the number of impacts when the tightening torque calculated by the tightening torque calculation unit reaches a predetermined torque value and the number of impacts stored in the reference impact number storage unit, In addition to the number of shut-off shocks set by the setting unit, the rotation of the motor is stopped when the counted number of shocks becomes the number of shut-off shocks obtained by adding the difference.
The impact rotary tool according to claim 4, wherein

Images