WO2018100801A1 - Impact rotary tool and method for setting shutoff impact count - Google Patents

Abstract

A setting unit 15 sets a shutoff impact count of an impact mechanism 9. An impact detection unit 12 detects impact applied to an output shaft 8 by the impact mechanism 9. A control unit 10 counts the number of impacts detected by the impact detection unit 12, and when the counted number of impacts reaches the shutoff impact count, rotation of a motor 2 is stopped. On the basis of a relationship between a target fastening torque value for when motor rotation is stopped at the shutoff impact count, and the actual fastening torque value actually measured when motor rotation is stopped at the shutoff impact count, the setting unit 15 corrects the shutoff impact count such that the fastening torque value when motor rotation is stopped becomes the target fastening torque value.

Description

Impact rotary tool and shutoff impact number setting method

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

The mechanical impact rotary tool tightens the screw member by generating an intermittent rotational impact force on the output shaft by hammering the output shaft in the rotational direction by a hammer rotating with the motor output. 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, but there is a problem that the cost and size of the tool increase. 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 counts the number of hits detected by the impact detection means and the number of hits detected by the hit detection means, and the counted number of hits corresponds to the number of hits corresponding to the tightening torque set by the user. A mechanical impact rotary tool provided with a control means for automatically stopping the motor will be disclosed.

JP 2009-83038 A

In the impact rotating tool, the correspondence between the tightening torque value and the number of impacts (impacts) for automatically stopping the motor (hereinafter also referred to as “shutoff impact number”) is stored in the master table of the memory. . A manufacturer of an impact rotary tool creates a master table by actually measuring the number of shut-off impacts for realizing each of a plurality of tightening torque values using a predetermined screw member and a fastened member. As a result, the master table holds the number of shut-off impacts corresponding to each set value of the tightening torque. When the user sets a target tightening torque value, the impact rotary tool controls the motor rotation based on the number of shutoff impacts held in the master table.

However, the screw member and the fastened member that are the work objects in the assembly factory or the like may be different from the screw member and the fastened member at the time of creating the master table. For example, if the fastened member that is the work target is softer than the fastened member at the time of creating the master table, if the impact rotary tool automatically stops the motor rotation at the number of shutoff impacts held in the master table, the tightening torque value will be The target value may not be reached. Conversely, if the work piece to be fastened is harder than the work piece to be fastened at the time of creating the master table, the impact rotating tool will automatically tighten when the motor rotation stops at the number of shutoff impacts held on the master table. The torque value may exceed the target value.

The present invention has been made in view of such circumstances, and an object thereof is to provide a technique for appropriately setting the number of shut-off shocks.

In order to solve the above problems, an impact rotary tool according to an aspect of the present invention includes an impact mechanism that generates an intermittent rotational impact force on an output shaft by a motor output, and a setting unit that sets the number of shut-off impacts of the impact mechanism And the impact detection unit that detects the impact applied to the output shaft by the impact mechanism, and counts the number of impacts detected by the impact detection unit, and stops the rotation of the motor when the counted number of impacts reaches the shut-off impact number And a control unit. Based on the relationship between the target tightening torque value when the motor rotation is stopped at the shut-off impact number and the actual tightening torque value measured by actually stopping the motor rotation at the shut-off shock number, The shut-off impact number is corrected so that the tightening torque value when the rotation is stopped becomes the target tightening torque value.

Another aspect of the present invention is a method for setting the number of shut-off impacts for automatically stopping motor rotation. This method sets an initial value for the number of shut-off impacts, actually sets the target tightening torque value when the motor rotation is stopped at the initially set number of shut-off impacts, and the actually set number of shut-off impacts. From the relationship with the actual tightening torque value measured by stopping the motor rotation, the number of shut-off impacts at which the tightening torque value when the motor rotation is stopped becomes the target tightening torque value is obtained.

It is a figure which shows the structure of the impact rotary tool which concerns on embodiment. It is a figure which shows the relationship between a target torque value and the number of shut-off impacts. It is a figure which shows the number of shut-off impacts corresponding to a predetermined target torque value. It is a figure which shows the estimated curve showing the relationship between a target torque value and the number of shut-off impacts, and the relationship between an actual fastening torque value and the number of impacts. It is a figure for demonstrating the number of impacts for obtaining a predetermined | prescribed tightening torque value. It is a figure which shows the flowchart of the process which correct | amends the number of shut-off impacts.

FIG. 1 shows a configuration of a mechanical 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.

As long as a force greater than a predetermined value 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 force 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 impact the anvil 7 and the output shaft 8 by the motor output and generate an intermittent rotational impact force on the output shaft 8. 9 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 has a function of controlling the rotation of the motor 2. The operation switch 16 is a trigger switch operated by a user, and the control unit 10 controls on / off of the motor 2 by operating the operation switch 16 and drives a drive 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 control unit 10 to adjust the motor rotation speed.

The impact detector 12 detects an impact applied to the output shaft 8 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 output shaft 8 by the impact mechanism 9 by detecting an impact sound, for example.

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.

In the embodiment, the shut-off impact number storage unit 17 stores the shut-off impact number corresponding to each set value of the target torque. 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 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 actually measures the number of shut-off impacts for realizing a plurality of tightening torque values using a predetermined screw member and a fastened member, and a torque coefficient which is a proportional constant in the calculation formula km may be obtained and stored in the shut-off impact number storage unit 17. Even when the shut-off impact number storage unit 17 stores the shut-off impact number corresponding to each set value of the target torque, each target torque value has a torque coefficient km as the square root of each shut-off impact number. Is the value multiplied by.

FIG. 2 shows the relationship between the target torque value stored in the shut-off impact number storage unit 17 and the shut-off impact number. From the above relationship, when the target torque value is T, the shut-off impact number is N, and the torque coefficient is km, the target torque value T is expressed by the following calculation formula.

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.

The setting unit 15 has a function of setting the shut-off impact number of the impact mechanism 9. Specifically, the setting unit 15 refers to the stored contents of the shut-off impact number storage unit 17 and stops the motor rotation with the function of setting the initial value of the shut-off shock number and the initially set shut-off shock number. It has a function of correcting the initially set shutoff impact number according to the tightening torque value measured later. In the latter correction function, the setting unit 15 sets the target torque value when the motor rotation is stopped at the initially set shut-off impact number and the tightening torque measured by actually stopping the motor rotation at the shut-off impact number. From the relationship with the value, the shut-off impact number is corrected so that the tightening torque value when the motor rotation is stopped becomes the target tightening torque value. Hereinafter, the function of the setting unit 15 will be described in detail.

* Before starting 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 embodiment, the setting unit 15 derives the shut-off shock number and supplies the shut-off shock number to the control unit 10, and the control unit 10 makes the shut-off shock number available for rotation control of the motor 2. This is called the setting process. The setting unit 15 sets the shut-off impact number derived from the stored contents of the shut-off impact number storage unit 17 as an initial value of the shut-off impact number.

In a work site where the same tightening operation is repeated, the user sets a target torque value and then checks whether the actual tightening torque value (hereinafter also referred to as “actual tightening torque value”) matches the target torque value. . This torque confirmation work must be performed before the tightening work is started. The user tightens the same screw member and the fastened member as the work target using the impact rotary tool 1 in which the target torque value is set, and the tightening torque of the screw member is set to the return torque method, the mark method, the additional tightening torque method, or the like. Measured by known inspection methods. At this time, if the actual tightening torque value matches the target torque value, the user confirms that the impact rotary tool 1 can be used for work as it is.

However, if the actual tightening torque value does not coincide with the target torque value, the user automatically stops the rotation of the motor 2 at the shut-off impact number stored in the shut-off impact number storage unit 17, and the target tightening torque value is reached. Check that the attached torque value cannot be achieved. Therefore, the setting unit 15 of the embodiment has a function of correcting and resetting the shut-off impact number so that the screw member can be tightened with the target torque value.

FIG. 3 shows the number of shut-off impacts corresponding to a predetermined target torque value. Hereinafter, a case where the user sets the target torque value Tm will be described as an example.
When the user sets the target torque value Tm, the setting unit 15 refers to the stored content of the shut-off impact number storage unit 17 and determines the shut-off impact number Nm associated with the target torque value Tm as the shut-off impact number. Set as initial value. When the user operates the operation switch 16, the control unit 10 supplies a drive instruction corresponding to the operation amount of the operation switch 16 to the motor drive unit 11, and the motor drive unit 11 rotates the motor 2 according to the drive instruction.

The control unit 10 monitors the output voltage of the impact detection unit 12, and when the output voltage of the impact detection unit 12 exceeds the impact determination voltage Vth, an intermittent rotational impact force is generated on the output shaft 8 by the impact mechanism 9. Judge that. The control unit 10 may include 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 a rotational impact force has occurred on the output shaft 8. The control unit 10 counts the number of impacts detected by the impact detection unit 12. When the counted number of impacts reaches the shut-off impact number Nm, the control unit 10 automatically stops the rotation of the motor 2. Thereafter, the user measures the actual tightening torque value of the tightened screw member by a known method.

FIG. 4 shows a curve C1 representing the relationship between the target torque value and the number of shutoff impacts with a solid line, and an estimated curve C2 representing the relationship between the actual tightening torque value and the number of impacts with a dotted line. In this example, in the torque checking operation, when the control unit 10 automatically stops the rotation of the motor 2 at the shut-off impact number Nm, the actual tightening torque value is measured as Tw.

As described above, the tightening torque value is a value obtained by multiplying the square root of the number of hits by the impact mechanism 9 by a predetermined torque coefficient. Therefore, if the tightening torque value Tw and the number of impacts (hitting number) Nm at that time are known, a torque coefficient kw which is a proportional constant can be obtained, and an estimated curve C2 representing the number of impacts N corresponding to the actual tightening torque value T. Can be derived. The estimated curve C2 is expressed by the following equation 2.

　ここで実締付トルク値Ｔｗに対する目標トルク値Ｔｍの比（つまり、Ｔｍ／Ｔｗ）をジョイント係数ｊと呼ぶと、式３と式４とから、

　したがって式２と式５とから、推定曲線Ｃ２は、以下の式で表現できる。

Referring to FIG. 4, in curve C1, the tightening torque value for impact number Nm is Tm, and in curve C2, the tightening torque value for impact number Nm is Tw. Therefore, if each value is substituted into Equation 1 and Equation 2,

Here, when the ratio of the target torque value Tm to the actual tightening torque value Tw (that is, Tm / Tw) is referred to as a joint coefficient j,

Therefore, from Equation 2 and Equation 5, the estimated curve C2 can be expressed by the following equation.

　このように締付トルク値Ｔｍを得るための衝撃数Ｎｗは、式７により、ジョイント係数ｊの２乗値と衝撃数Ｎｍとから求められる。 FIG. 5 is a diagram for explaining the number of impacts Nw by the impact mechanism 9 for obtaining the tightening torque value Tm. From Equation 3 and Equation 6, the impact number Nw is obtained by Equation 7 below.

Thus, the impact number Nw for obtaining the tightening torque value Tm is obtained from the square value of the joint coefficient j and the impact number Nm by Equation 7.

When the user measures the actual tightening torque value Tw when the rotation of the motor 2 is automatically stopped at the initially set shut-off impact number Nm, the setting unit 15 uses the joint coefficient j (= Tm / Tw). Thus, the number of impacts Nw for actually obtaining the tightening torque value Tm can be calculated by Equation 7. Therefore, when the user measures the actual tightening torque value Tw, the actual tightening torque value Tw or the joint coefficient j is input to the impact rotary tool 1 using the remote controller.

The receiving unit 14 receives the actual tightening torque value Tw or the value of the joint coefficient j (= Tm / Tw) input by the user. The setting unit 15 calculates the square value of the joint coefficient j using Equation 7, and multiplies the initially set shut-off impact number Nm so that the tightening torque value when the motor rotation is stopped is the target. A shut-off impact number Nw that is a torque value is obtained. The setting unit 15 supplies the calculated shutoff impact number Nw to the control unit 10. When the user inputs the actual tightening torque value Tw or the value of the joint coefficient j, the torque checking operation is finished, and thereafter, the control unit 10 uses the shut-off impact number Nw corrected by the setting unit 15 to use the motor 2 Control the rotation of

If the joint coefficient j related to the work target is determined in this way, the same joint coefficient j can be used even when the target torque value is varied for the same work target. Therefore, if there is no change in the work target, when the user changes the target torque value, the setting unit 15 automatically sets the shut-off impact number for obtaining the target torque value. Even if the same target torque value is set, if there is a change in the combination of the screw member and the fastened member that is the work target, the user must check the torque each time and measure the actual tightening torque. A value or a joint coefficient needs to be input to the impact rotary tool 1.

FIG. 6 shows a flowchart of processing for correcting the initial value of the number of shut-off shocks.
In the torque check operation, when the user selects the target torque value Tm using the remote controller, the receiving unit 14 receives a selection input of the target torque value Tm, and the setting unit 15 stores the stored contents of the shut-off impact number storage unit 17. Referring to, an initial value Nm of the number of shutoff impacts is set (S10).

When the user inserts a screw member into a tip tool provided at the tip of the output shaft 8 and operates the operation switch 16, the control unit 10 supplies a drive instruction for the motor 2 to the motor drive unit 11 (S12). Thereby, the motor 2 is rotated and tightening of the screw member is started. The impact detection unit 12 detects an impact applied to the output shaft 8 by the impact mechanism 9, and the control unit 10 counts the number of impacts detected by the impact detection unit 12, and the counted number of impacts is a shut-off impact. When it reaches several Nm, the rotation of the motor 2 is stopped (S14).

Then, the user measures the actual tightening torque value Tw of the screw member. If the actual tightening torque value Tw matches the target torque value Tm, the user confirms that the shut-off impact number Nm is appropriate. On the other hand, if the actual tightening torque value Tw is different from the target torque value Tm, the user uses the remote controller to set the actual tightening torque value Tw or the joint coefficient j (= Tm / Tw) to the impact rotary tool 1. input. As another input method, the user may input the actual tightening torque value Tw or the joint coefficient j by operating the buttons and the touch panel of the impact rotary tool 1. Further, the impact rotary tool 1 may be connected to a terminal device such as a computer, and the actual tightening torque value Tw or the joint coefficient j may be input from the terminal device. The reception unit 14 receives a value input by the user and supplies the value to the setting unit 15.

The setting unit 15 derives the shut-off impact number Nw for obtaining the tightening torque value Tm from the value input by the user using Equation 7, and corrects the initially set shut-off impact number Nm. The setting unit 15 supplies the derived shutoff impact number Nw to the control unit 10, and thereafter, the control unit 10 controls the rotation of the motor 2 using the shutoff impact number Nw. According to the embodiment, the setting unit 15 can appropriately control the tightening torque by correcting the initially set shut-off impact number from the relationship between the target torque value Tm and the actual tightening torque value Tw. It becomes possible.

The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to each component or combination of each processing process, and such modifications are within the scope of the present invention. .

　なおｎ＝０であれば、式１’、式２’、式７’は、式１、式２、式７と同じになる。 In the embodiment, in the formulas 1 and 2, the tightening torque is derived from the first hit. However, in the impact rotary tool 1, for example, when moving average is used for processing time-series data, it is necessary to wait for data processing until the minimum number of data necessary for data processing is obtained. In this case, in the master table, the target torque value for the first several times (n) from the start of impact is not set, and the setting unit 15 also generates an estimated curve for generating tightening torque from the (n + 1) th impact. Designed to do. At this time, Equation 1, Equation 2, and Equation 7 are modified as follows.

If n = 0, Formula 1 ′, Formula 2 ′, and Formula 7 ′ are the same as Formula 1, Formula 2, and Formula 7.

In the embodiment, the user inputs the actual tightening torque value Tw or the joint coefficient j to the impact rotary tool 1, and the impact rotary tool 1 corrects the initially set shut-off impact number Nm to the shut-off impact number Nw. I explained that. This correction process is performed by the setting unit 15, but in a modification, the function of the setting unit 15 is provided in a terminal device such as a computer, and the terminal device performs the correction process and corrects the number of shut-off shocks Nw. May be supplied to the impact rotary tool 1.

Further, although the impact rotary tool 1 of the embodiment includes the 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 a setting for setting the number of shut-off impacts of the impact mechanism. Part (15), the impact detection part (12) applied to the output shaft by the impact mechanism, and the number of impacts detected by the impact detection part are counted, and when the counted number of impacts becomes the shut-off impact number, And a control unit (10) for stopping the rotation.
The setting unit (15) has a relationship between a target tightening torque value when the motor rotation is stopped at the shut-off impact number and an actual tightening torque value measured by actually stopping the motor rotation at the shut-off shock number. Therefore, the shut-off impact number is corrected so that the tightening torque value when the motor rotation is stopped becomes the target tightening torque value.

The setting unit (15) may set an initial value of the shut-off impact number, and correct the initially set shut-off impact number from the relationship between the target tightening torque value and the actual tightening torque value. The setting unit (15) calculates the square value of (target tightening torque value / actual tightening torque value), so that the tightening torque value when the motor rotation is stopped is equal to the target tightening torque value. The shut-off impact number may be obtained. The impact rotary tool 1 further includes a reception unit (14) that receives an actual tightening torque value input by a user or a value of (target tightening torque value / actual tightening torque value), and the setting unit (15) includes Based on the input value, the shut-off impact number at which the tightening torque value when the motor rotation is stopped becomes the target tightening torque value may be obtained.

According to another aspect of the present invention, the number of impacts by the impact mechanism (9) is counted, and when the counted number of impacts reaches the shut-off impact number, the shut-off is performed in the impact rotary tool (1) that stops the rotation of the motor (2). This is a method of setting the number of impacts. This method sets an initial value for the number of shut-off impacts, actually sets the target tightening torque value when the motor rotation is stopped at the initially set number of shut-off impacts, and the actually set number of shut-off impacts. From the relationship with the actual tightening torque value measured by stopping the motor rotation, the number of shut-off impacts at which the tightening torque value when the motor rotation is stopped becomes the target tightening torque value is obtained.

DESCRIPTION OF SYMBOLS 1 ... Impact rotary tool, 2 ... Motor, 9 ... Impact mechanism, 10 ... Control part, 11 ... Motor drive part, 12 ... Impact detection part, 14 ... Reception part , 15 ... setting unit, 17 ... shut-off impact number storage unit.

The present invention can be used for tools such as impact rotary tools.

Claims (5)

An impact mechanism that generates intermittent rotational impact force on the output shaft by motor output, a setting unit that sets the number of shutoff impacts of the impact mechanism, and impact detection that detects impact applied to the output shaft by the impact mechanism An impact rotating tool comprising: a control unit that counts the number of impacts detected by the impact detection unit, and stops the rotation of the motor when the counted number of impacts becomes a shut-off impact number,
From the relationship between the target tightening torque value when the motor rotation is stopped at the shut-off impact number and the actual tightening torque value actually measured by stopping the motor rotation at the shut-off shock number, the setting unit is Correct the shut-off impact number so that the tightening torque value when the motor rotation is stopped becomes the target tightening torque value.
An impact rotary tool characterized by that. The setting unit sets an initial value of the shut-off impact number, and corrects the initially set shut-off impact number from the relationship between the target tightening torque value and the actual tightening torque value.
The impact rotary tool according to claim 1. The setting unit calculates a square value of (target tightening torque value / actual tightening torque value), so that the tightening torque value when the motor rotation is stopped becomes the target tightening torque value. Find the impact number,
The impact rotary tool according to claim 1, wherein the impact rotary tool is provided. A receiving unit for receiving an actual tightening torque value input by a user or a value of (target tightening torque value / actual tightening torque value);
The setting unit obtains a shut-off impact number at which the tightening torque value when the motor rotation is stopped becomes the target tightening torque value based on the input value.
The impact rotary tool according to any one of claims 1 to 3, wherein the impact rotary tool is provided. Counting the number of impacts by the impact mechanism and setting the number of shutoff impacts in an impact rotating tool that stops the rotation of the motor when the counted number of impacts becomes the shutoff impact number,
Set the initial value of the shut-off impact number,
The target tightening torque value when the motor rotation is stopped at the initially set shut-off impact number and the actual tightening torque value measured by actually stopping the motor rotation at the initially set shut-off impact number. From the relationship, obtain the number of shut-off impacts at which the tightening torque value when the motor rotation is stopped becomes the target tightening torque value.
A method for setting the number of shut-off impacts.

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