JP2001341079A - Power-driven rotary tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power driven rotary tool capable of certainly carrying out thread fastening work of a plural number of kinds of thread members different in fastening torque from each other without carrying out setting work of the fastening torque. SOLUTION: A motor control part 12 controls revolution of a motor 1 in accordance with drawing quantity of a trigger switch 7. A load torque estimation part 8 estimates load torque applied on an output shaft 6, and when its estimated value reaches proper fastening torque of the first or second thread member, a shut-off judgement part 10 outputs a first or second shut-off command to stop the motor 1 to the motor control part 12. The motor control part 12 stops the motor 1 regardless of operation of the trigger switch 7 when the first shut-off command is input, rotates the motor 1 again at a point of time when stopping time passes in the case when the trigger switch 7 is not released before the specified stopping time passes after the motor 1 is stopped and stops the motor 1 again at a point of time when the second shut-off command is input.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power-driven rotary tool such as an impact wrench or an impact driver used for tightening and loosening screws such as bolts and nuts.

[0002]

2. Description of the Related Art As a power-driven rotary tool of this type, as shown in FIG. 9, a hammer 3 is driven to rotate by a motor 1 and a striking impact from the hammer 3 is applied to the output shaft 5 to rotate the output shaft 5. By using a driver bit 6 mounted on the output shaft 5 or a bit such as a socket wrench, an impact driver or an impact rotary tool such as an impact wrench for tightening or loosening screws such as bolts and nuts is provided. Was.

The impact rotary tool includes a load torque estimating section 8 for estimating a torque applied to the output shaft 5, a limit torque setting device 20 for setting a tightening torque according to a member to be tightened, and a load torque estimating section 8. It is determined whether or not the screw member is seated according to the height of the estimated value and the set value of the tightening torque set by the limit torque setting device 20. When the seating of the screw member is determined, the motor 1 is stopped (shut down). And a shut-off determination unit 10 that generates a stop command (shut-off command) for turning off.

When the screw tightening operation is performed, the shut-off determining unit 10 compares the estimated value of the load torque estimating unit 8 with the set value of the limit torque setting unit 20, and determines whether the load torque estimating unit 8 When the estimated value exceeds the set value of the tightening torque, it is determined that the screw member is seated, and the rotation of the motor 1 is stopped.

[0005]

In the above-described impact rotary tool, when performing the screw tightening operation, the tightening torque is set in advance according to the type of the screw member to be tightened by using the limit torque setting device 20, and then the screw is tightened. I was working. Therefore, when performing the screw tightening work of a plurality of types of screw members having different tightening torques, it is necessary to set the tightening torque for each of the different types of screw members, and there is a problem that the setting work is troublesome.

Therefore, among the plurality of screw members having different tightening torques, for the screw members having overlapping allowable torque ranges, the same value is set for the tightening torque, so that the work of setting the tightening torque is reduced to some extent. Although it is possible to do so, it is necessary to change the setting of the tightening torque for the screw members whose allowable torque ranges do not overlap, and there is a problem that the workability is poor. In addition, there is a limit to the standardization of the tightening torque.If the standardized tightening torque is near the boundary of the allowable torque range, the tightening torque is insufficient due to manufacturing variations of the screw members, etc. Stops the screw member,
Further, an excessive tightening torque may be applied, and the screw member may penetrate the mating member or the screw member may be damaged, so that the quality of the screw tightening may be deteriorated.

Further, when the tightening torque is set by using the limit torque setting device 20, if the value is mistakenly set to a value lower than an appropriate value, the tightening torque becomes insufficient and the screw member is tightened. It was necessary to stop in the middle of the attachment and perform the screw tightening work again. Also, if a value higher than the appropriate value is set, excessive tightening torque is applied to the screw member, and the screw member penetrates the mating member, the screw member is damaged, and the like. May need to be replaced, and the quality of screw tightening may be reduced.

In addition, no thread groove is formed on the surface,
A metal screw member (hereinafter, referred to as a "soft joint member") is used in place of a synthetic resin member (hereinafter, referred to as a "soft joint member") such as a resin grommet that tightens a screw while cutting a screw groove by being screwed into a screw hole. When the screw tightening operation of the “hard joint member” is performed using the above-described impact rotary tool, when the change speed of the estimated torque value reaches a predetermined value, it is determined that the screw member is a soft joint member. If the screw tightening operation is stopped regardless of the tightening torque and the change rate of the estimated torque value is less than a predetermined value, it is determined that the screw member is a hard joint member, and the tightening torque is determined to be appropriate for the hard joint member. A method has been proposed in which the screw tightening work is stopped when the tightening torque is reached, eliminating the need to set the tightening torque. Since bets can not be set a plurality of tightening torque in the case of members, there is a problem that can not be performed simultaneously screwing operation only the same hard joint member of tightening torque.

[0009] Further, after baking coating on the iron plate having the screw holes formed therein, when screwing the screw member with a spring washer interposed between the screw holes formed in the iron plate, the paint adhered to the screw holes is peeled off while removing. After screwing the screw member into the screw hole, the spring washer is crushed by the screw member, so the transition of the load torque is very similar to the transition of the load torque generated when tightening the soft joint member described above. May not be attached. Therefore, even though the hard joint member is fastened to the screw hole provided in the iron plate, the shutoff determination unit 10 determines that the soft joint member is used, and stops the tightening operation at a stage where the tightening torque is small. There was also a problem that the tightening torque was insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to perform screw tightening of a plurality of types of screw members having different tightening torques without performing the work of setting the tightening torques. An object of the present invention is to provide a power-driven rotary tool capable of reliably performing an operation.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a power-driven rotary tool used for tightening and loosening a plurality of types of screw members having different proper tightening torques. An output shaft for tightening and loosening members, a drive unit for rotating the output shaft, a trigger switch for generating an operation signal according to the retracted amount, and rotation of the drive unit for an operation signal input from the trigger switch A drive control unit for controlling the number of motors, a load torque estimating unit for estimating the load torque applied to the output shaft, and stopping the driving unit each time the estimated value of the load torque estimating unit reaches the appropriate tightening torque of each screw member. A shut-off determination unit that outputs a stop command to the drive control unit, wherein the drive control unit, when a stop command is input from the shut-off determination unit, regardless of the operation signal of the trigger switch, drives the drive unit. If the trigger switch is not opened between the time when the predetermined stop time elapses after the drive unit is stopped and the drive unit is stopped, the drive unit is rotated again when the stop time elapses, and the shut-off determination unit is provided. Outputs a stop command to the drive control unit when the load torque reaches the appropriate tightening torque of each screw member, and when the stop command is input, the drive control unit stops the drive unit for a predetermined stop time. Therefore, if the trigger switch is opened during this time, the load torque can be set to the appropriate tightening torque at this time. On the other hand, if the trigger switch is continued to be pulled during the elapse of the stop time, the drive control unit restarts the rotation of the drive unit, and when the load torque reaches the appropriate tightening torque, the drive control unit receives the input from the shut-off determination unit. Since the drive unit is stopped by the stop command, the trigger switch is opened when the load torque reaches the desired appropriate tightening torque,
The screw member can be tightened to a desired appropriate tightening torque, and the current tightening torque can be ascertained by the number of times the drive unit has stopped. Therefore, it is possible to efficiently perform the screw tightening operation of a plurality of screw members having different tightening torques without performing the tightening torque setting operation, and set the tightening torque as in the conventional power-driven rotary tool. Since a torque setting device is not required, the size and cost of the power-driven rotary tool can be reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, a load variation detecting section for detecting a variation of the estimated value of the load torque estimating section per predetermined time is provided, and the shut-off determining section includes a load variation determining section. When the fluctuation amount detected by the amount detection unit becomes equal to or more than a predetermined threshold value, a stop command is first output to the drive control unit, and when a screwing operation of a soft joint member such as a resin grommet is performed, a seating is performed. Immediately after the screw tightening operation is completed, the tightening torque becomes an appropriate value.However, the shut-off determination unit first issues a stop command when the variation detected by the load variation detection unit exceeds a predetermined threshold. Since the output is output, if the trigger switch is opened when the drive unit is first stopped by the drive control unit, the time when the fluctuation amount of the load torque sharply increases, that is, when the screw member is seated The driving unit can be stopped, it performs the screwing operation of the soft joint member in torque with appropriate fastening.

According to a third aspect of the present invention, in the first or second aspect, the stop time is approximately 0.2 seconds or more and approximately 1 second or less. When the screw tightening work is completed at the time when the time has reached, the driving unit is restarted when it is time to secure enough time for the operator to release the trigger switch and when the screw tightening work is to be continued. It is desirable to set the waiting time until the user does not feel long, and the stop time is preferably about 0.2 seconds or more and about 1 second or less.

According to a fourth aspect of the present invention, in the first to third aspects, a stop time setting unit for changing a set value of the stop time is provided. The drive unit is restarted when it is time to allow the operator to release the trigger switch when the screw tightening work is to be terminated when the torque is reached, and when the screw tightening work is to be continued. It is desirable to set the waiting time until the user does not feel a long waiting time, and the stopping time setting unit can set the stopping time to a desired time.

According to a fifth aspect of the present invention, in the second aspect of the present invention, when the variation detected by the load variation detecting section does not exceed the threshold value, the estimated value of the load torque estimating section is set to a desired value. When the stop torque is reached and a stop command is input from the shut-off determination unit to the drive control unit, the drive control unit stops the drive unit regardless of the operation signal of the trigger switch, and then stops the drive unit. If the trigger switch is not opened before the stop time elapses, after the stop time elapses, the drive unit is rotated for a sufficiently short time so that an operator can recognize the rotation of the drive unit, and then the drive unit is rotated. Depending on the type of screw member and the design of the combination thereof, the estimated value of the load torque estimating unit may be reduced when the variation detected by the load variation detecting unit does not exceed the threshold. screw In some cases, the proper tightening torque of the material may be reached. In such a case, the number of times the drive unit stops until the desired proper tightening torque is reached is reduced by one time from the number expected by the operator, and the desired torque is reduced. In some cases, the operator may not know whether the screw tightening operation has been completed or not.However, when the variation detected by the load variation detecting unit does not exceed the threshold value, the estimated value of the load torque When the appropriate tightening torque is reached and a stop command is input from the shut-off determination unit to the drive control unit, the trigger switch must be opened between the time when the drive unit was stopped and the time when a predetermined stop time has elapsed. For example, when the stop time has elapsed, the drive control unit rotates the drive unit for a predetermined time and then stops, so the number of times the drive unit stops until the tightening torque reaches the desired appropriate tightening torque To Since the correction can be made by increasing the number of batches, it is possible to inform the operator that the screw member has been tightened with the desired proper tightening torque, and in this case, the rotation amount of the drive unit rotated by the drive control unit is Since it is sufficiently small, the tightening torque accuracy does not greatly deteriorate.

[0016]

Embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention.
This will be described with reference to FIGS. This power-driven rotary tool drives the hammer 3 by the motor 1 to rotate the hammer 3.
The output shaft 5 is rotated by applying a shock to the output shaft 5, and a screw such as a bolt or a nut is tightened or loosened by a screw such as a driver bit 6 or a socket attached to the output shaft 5. It is an impact rotary tool such as an impact driver or an impact wrench, and uses the following as a striking structure using the hammer 3. That is, a cylindrical hammer 3 is freely rotatably disposed on the outer periphery of a drive shaft 2a to which the rotation of the motor 1 is transmitted by being reduced by a speed reducer 2 comprising a planetary reduction mechanism. The movement of the drive shaft 2a and the hammer 3 in the axial direction and the movement in the direction around the axis are restricted by a cam mechanism (not shown) formed in the above. The hammer 3 urged toward the output shaft 5 by the spring 4 has a striking portion which engages with an anvil 5 a projecting laterally from the rear end of the output shaft 5. 3a is provided.

When the driver bit 6 and the output shaft 5 to which the socket is attached at the tip are hardly loaded, the rotation of the drive shaft 2a is transmitted to the hammer 3 via the cam mechanism. Is transmitted to the output shaft 5 by engagement of the hitting portion 3a of the hammer 3 with the anvil 5a. If the load applied to the output shaft 5 increases, relative rotation occurs within the range permitted by the cam mechanism between the hammer 3 and the drive shaft 2a, and the hammer 3 is guided by the cam mechanism.
Is retracted against the spring 4, the striking portion 3a is disengaged from the anvil 5a and the striking portion 3a gets over the anvil 5a, and the hammer 3 is guided by the cam mechanism by the restoring force of the spring 4 to move forward. The impact portion 3a is impactedly engaged with the anvil 5a to apply a rotational force to the output shaft 5 by the impact impact.
Here, a striking mechanism that applies a rotational force due to a striking impact to the output shaft 5 from the hammer 3, the spring 4, the anvil 5a, and the like is configured.

Incidentally, the motor control unit 1 as a drive control unit
A motor control circuit 2 controls the number of revolutions of the motor 1 according to the amount of pull-in of the trigger switch 7.
3, the rotation speed of the motor 1 is variably controlled by adjusting the power supplied from the rechargeable battery 14 to the motor 1 in accordance with a control signal input from the motor control unit 12. That is, the motor control circuit 13 includes a switching element inserted into a power supply path from the rechargeable battery 14 to the motor 1 and a drive circuit that turns on / off the switching element in accordance with a control signal input from the motor control unit 12 described later. By changing the on-duty ratio of the switching element, for example, according to a control signal input from the motor control unit 12, the supply power is adjusted to change the rotation speed of the motor 1. .

In this embodiment, for example, a load torque estimating unit 8 for estimating a load torque applied to the output shaft 5 from a change in the number of revolutions of the motor 1 and a screw member seated on the basis of the estimated value of the load torque estimating unit 8. The motor control unit 12 is provided with a shut-off determination unit 10 that determines and outputs a shut-off command (stop command) for stopping the motor 1 to the motor control unit 12. The motor control unit 12 receives a shut-off command from the shut-off determination unit 10. Then, the motor control circuit 13 is controlled to stop the rotation of the motor 1. The load torque estimating unit 8 obtains, for example, a moving average of the past four estimated values, and outputs the average value to the shut-off determining unit 10 as an estimated value. The method of estimating the load torque by the load torque estimating unit 8 is not limited to the above method. For example, a torque sensor may be used, the amount of current and voltage of the motor 1, the advancing angle of the bit, the rebound of the hammer 3 The load torque may be estimated from the amount or the like. In the present embodiment, the load torque estimating unit 8, the shut-off determining unit 10, and the motor control unit 12 are configured by a microcomputer.

The shutoff determination section 10 provides an appropriate tightening torque for the first screw member (hereinafter referred to as a first threshold).
And a value of an appropriate tightening torque (hereinafter, referred to as a second threshold) of the second screw member are set in advance, and the second threshold is set to a value higher than the first threshold. I have. In the present embodiment, an example will be described in which two types of screw members having different proper tightening torques are tightened.

Here, the load torque estimating section 8 uses the hammer 3
The load torque estimating unit 8 outputs the estimated value of the load torque every time the impact occurs.
When the estimated value of the load torque is input to 0, the shutoff determination unit 10 compares the estimated value of the load torque with the first and second thresholds, and the estimated value of the load torque becomes the first threshold. When it reaches, the first shut-off command is output to the motor control unit 12, and when the estimated value of the load torque reaches the second threshold, the second shut-off command is output to the motor control unit 12.

The motor control unit 12 controls the rotation speed of the motor 1 in accordance with the amount of pull-in of the trigger switch 7,
When a shut-off command is input from the shut-off determination unit 10, regardless of the pull-in operation of the trigger switch 7,
The motor 1 is stopped. Here, the shut-off determination unit 1
If the shut-off command input from 0 is the first shut-off command based on the first threshold, the trigger switch 7 must be opened between the time when the motor 1 is stopped and a predetermined stop time elapses. When the stop time has elapsed, the motor control unit 12 rotates the motor 1 again. On the other hand, when the shut-off command input from the shut-off determination unit 10 is the second shut-off command based on the second threshold, the motor control unit 12 stops the motor 1
Is not restarted.

Hereinafter, the control operation of the motor 1 will be described with reference to the flowchart of FIG. After initializing each unit when the power is turned on (S2 in FIG. 2), the motor control unit 12 reads the input from the trigger switch 7 (S3 in FIG. 2) and determines whether or not the trigger switch 7 is pulled in by the operator. When the trigger switch 7 is pulled in, the motor 1 is started (S4 in FIG. 2).
5).

Thereafter, the motor control unit 12 monitors whether the trigger switch 7 is released or whether a shut-off command is input from the shut-off determination unit 10 (S6 in FIG. 2). If the switch 7 has not been released and the shut-off command has not been input, a rotation process for rotating the motor 1 is performed (S8 in FIG. 2), and after reading the input from the trigger switch 7 (S9 in FIG. 2), FIG. S
6, the above-described processing is repeated, and the rotation of the motor 1 is controlled in accordance with the retracted amount of the trigger switch 7 until the trigger switch 7 is opened or a shut-off command is input.

On the other hand, whether the trigger switch 7 is released,
Alternatively, when a shut-off command is input from the shut-off determination unit 10, the motor control unit 12 outputs a stop signal for temporarily stopping the motor 1 to the motor control circuit 13,
A process for temporarily stopping the motor 1 is performed (S in FIG. 2).
7) It is determined whether the shut-off command input from the shut-off determining unit 10 is a first shut-off command based on a first threshold (S10 in FIG. 2).

If the shut-off command is based on the first threshold value, the motor control unit 12 reads the input from the trigger switch 7 (S12 in FIG. 2) and determines whether the trigger switch 7 is released. (S1 in FIG. 2)
3). If the trigger switch 7 has not been released, it is determined whether or not a predetermined stop time has elapsed since the motor 1 was stopped (S14 in FIG. 2). If the stop time has not elapsed, the process returns to S12. After returning, the above-described processing is repeated. If the stop time has elapsed, a restart processing for rotating the motor 1 again is performed (S16 in FIG. 2), and then S6 in FIG.
And the above processing is repeated.

If the shut-off command is not based on the first threshold value or the trigger switch 7 is opened before the stop time elapses, the motor control unit 12
Reads the input from the trigger switch 7 (S1 in FIG. 2).
1) It is determined whether or not the trigger switch 7 is opened (S15 in FIG. 2). When the trigger switch 7 is opened,
It returns to S1 of FIG.

By the way, every time the hitting by the hitting mechanism occurs, an interrupt occurs, and a shut-off determination process described later is performed. Hereinafter, the shutoff determination processing will be described with reference to the flowchart of FIG.

When a striking by the striking mechanism occurs, the load torque estimating unit 8 estimates the load torque applied to the driver bit 6 from the number of rotations of the motor 1 during striking and the rotating speed of the motor 1 during striking, and a shut-off determining unit. 10 (S21 in FIG. 3). When the estimated value of the load torque is input from the load torque estimating unit 8, the shut-off determining unit 10 determines whether or not a first shut-off command has been generated (S22 in FIG. 3). If the first shut-off command has not been issued, the estimated value of the load torque (estimated torque)
And the first threshold value is compared (S23 in FIG. 3). When the estimated value of the load torque reaches the first threshold, the first
Is output to the motor control unit 12 (S25 in FIG. 3). On the other hand, if the first shut-off command has already been issued, or if the estimated value of the load torque is equal to or less than the first threshold, the shut-off determination unit 10 determines whether the estimated value of the load torque is equal to the second threshold. Compare the height (S2 in FIG. 3)
4) When the estimated value of the load torque reaches the second threshold, the second
Is output to the motor control unit 12 (S26 in FIG. 3).

When the estimated torque of the load torque estimating section 8 reaches the first threshold, the shut-off determining section 10 outputs a first shut-off command to the motor control section 12, and the motor control section 12 Since the rotation of the motor 1 is stopped for a predetermined stop time in response to the first shut-off command, if the trigger switch 7 is opened when the rotation of the motor 1 is stopped, the tightening torque of the screw member is reduced to the first torque. And the first screw member can be screwed with an appropriate tightening torque. On the other hand, when the screwing operation of the second screw member is being performed, the trigger switch 7 is held even after the motor 1 is stopped.
Is continued, the motor control unit 12 rotates the motor 1 again when a predetermined stop time has elapsed since the stop of the motor 1, and stops the motor 1 when the load torque reaches the second threshold value. Therefore, the screwing operation of the second screw member can be performed with an appropriate tightening torque.

In this embodiment, the case where two kinds of screw members having different proper tightening torques are tightened has been described. And the load torque estimating unit 8
When the estimated value of? Reaches the appropriate tightening torque of each screw member, the shutoff determination unit 10 may output a stop command to the motor control unit 12, and the motor control unit 12 may output the stop command from the shutoff determination unit 10. When a stop command is input from the controller, the motor 1 is stopped irrespective of the operation signal of the trigger switch 7, and if the trigger switch 7 is not opened until a predetermined stop time elapses after the motor 1 is stopped, the motor 1 is stopped. When the time has passed, the motor 1 is rotated again, and this operation is repeated until the estimated torque of the load torque estimating unit 8 reaches the appropriate tightening torque of the screw member having the highest appropriate tightening torque. Even when performing the screw tightening work of three or more types of screw members, the screw tightening work of a plurality of screw members having different proper tightening torques without setting the tightening torque. Efficiently it can be performed, and because the torque setter for setting a tightening torque is not required as in the conventional power-driven rotary tool, it is possible to reduce the size of the power-driven rotary tool, a cost reduction. Further, the current tightening torque can be grasped from the number of times the motor 1 is stopped.

The stop time for the motor control unit 12 to temporarily stop the rotation of the motor 1 is set to a time when the screw tightening operation is to be terminated when the load torque reaches the appropriate tightening torque of the first screw member. If the time is such that the operator can release the trigger switch 7 and the screw tightening operation is to be completed when the load torque reaches the appropriate tightening torque of the second screw member, the motor It is desirable to set the time so that the waiting time until the restart of 1 is not felt long. In the present embodiment, it is set to, for example, approximately 0.45 seconds. Note that the stop time is not intended to be limited to 0.45 seconds, but may be appropriately set to a time that satisfies the above conditions, for example, to a time of about 0.2 seconds or more and about 1 second or less. Is preferred.

(Embodiment 2) Embodiment 2 of the present invention is shown in FIG.
This will be described with reference to FIG. In the present embodiment, in the power-driven rotary tool of the first embodiment, the load torque estimating unit 8
The load fluctuation amount evaluation unit (load fluctuation amount detection unit) 11 that calculates the fluctuation amount of the load torque from the transition of the estimated value of the load torque estimated by the above is provided. Since the configuration other than the load fluctuation amount evaluation unit 11 is the same as that of the first embodiment, the same components are denoted by the same reference numerals, and description thereof will be omitted.

The load torque estimating unit 8 estimates the load torque every time a striking by the striking mechanism occurs, and outputs the estimation result to the shut-off judging unit 10 and the load fluctuation evaluating unit 11. The load variation estimating unit 11 may output the difference between the estimated value of the load torque estimating unit 8 at the time of the previous impact and the estimated value of the load torque estimating unit 8 at the time of the next impact as a variation. However, when noise resistance is taken into consideration, it is desirable to perform band-pass filter processing. As an example of the band-pass filter processing, there is a method in which the load fluctuation amount evaluating unit 11 calculates a short-term moving average and a long-term moving average of the estimated value of the load torque estimating unit 8 and outputs a difference between the two as a fluctuation amount. . For example, the load fluctuation amount evaluation unit 11 calculates a moving average of four estimated values up to the present as a short-term moving average, and calculates a moving average of 16 estimated values up to the present as a long-term moving average. When the difference is obtained to obtain the load fluctuation amount dT, the estimated values of the load torque output by the load torque estimating unit 8 up to the present are T1, T2, T3,..., T2.
If it is set to 0, the load fluctuation amount dT is expressed by the following equation.

[0036]

(Equation 1)

In the shut-off determining section 10, when the load variation dT calculated by the load variation evaluating section 11 becomes equal to or more than a predetermined threshold value (hereinafter, referred to as a third threshold value).
The first shut-off command is output to the motor control unit 12 and the second shut-off command is output to the motor control unit 12 when the estimated value of the load torque reaches the second threshold.

Here, the shut-off determination processing will be described with reference to the flowchart of FIG. Motor 1
Is the same as that of the first embodiment, and a description thereof will be omitted.

When a striking by the striking mechanism occurs, the load torque estimating unit 8 estimates the load torque applied to the driver bit 6 from the number of rotations of the motor 1 during striking and the rotating speed of the motor 1 during striking, and a shut-off determining unit. 10 and output to the load fluctuation amount evaluation unit 11 (S31 in FIG. 5). The load fluctuation evaluating section 11 obtains the load fluctuation dT of the load torque from the estimated value of the load torque estimating section 8 and outputs the load fluctuation dT to the shut-off determining section 10. The shut-off determination unit 10 determines whether the first shut-off command based on the third threshold has already been output (S32 in FIG. 5), and if the first shut-off command has not been output, the load change The magnitude of the load variation dT obtained by the quantity evaluator 11 is compared with the third threshold (S3 in FIG. 5).
3). Then, if the load fluctuation amount dT is equal to or larger than the third threshold value, the first shut-off command is output to the motor control unit 12 (S35 in FIG. 5). On the other hand, if the first shut-off command has already been output, or if the load variation dT is less than the third threshold, the shut-off determining unit 10 compares the estimated torque with the second threshold. (S34 in FIG. 5), when the estimated torque reaches the second threshold, a second shut-off command is output to the motor control unit 12 (S36 in FIG. 5).

By the way, in the case of performing the screw tightening operation of the soft joint member described above, if the screw tightening operation is completed immediately after seating, the tightening torque becomes an appropriate value. By detecting the seating of the screw member and terminating the screw tightening operation, the screw tightening operation of the soft joint member can be performed with an appropriate tightening torque. That is, in the present embodiment, when the load fluctuation amount dT of the load torque obtained by the load fluctuation amount evaluation unit 11 becomes equal to or more than the third threshold, the shut-off determination unit 10 outputs the first shut-off command to the motor control unit 12. However, since the motor control unit 12 stops the rotation of the motor 1, when the screwing operation of the soft joint member is performed, the trigger switch 7 is opened when the rotation of the motor 1 first stops. The screw tightening operation can be terminated immediately after the soft joint member is seated, and the soft joint member can be tightened with an appropriate tightening torque. On the other hand, when the hard joint member is being screwed in, if the trigger switch 7 is kept pulled even after the motor 1 is first stopped, the motor 1
When a predetermined stop time has elapsed from the stop of the motor, the motor control unit 12 rotates the motor 1 again, and the load torque becomes the second.
When the threshold value is reached, the shut-off determination unit outputs the second shut-off command to the motor control unit 12 and stops the motor 1, so that the screw tightening operation of the hard joint member is performed with an appropriate tightening torque. It can be carried out.

The stop time at which the motor control unit 12 temporarily stops the rotation of the motor 1 is set to a time when the operator wants to end the screw tightening work when the variation in the load torque becomes equal to or more than the third threshold. If it is time to release the trigger switch 7 and it is desired to complete the screw tightening operation when the load torque reaches the appropriate tightening torque of the second screw member, the motor 1 It is desirable to set the waiting time until restarting so that the user does not feel a long time. In the present embodiment, the waiting time is set to, for example, approximately 0.45 seconds. Note that the stop time is not intended to be limited to 0.45 seconds, but may be appropriately set to a time that satisfies the above conditions, for example, to a time of about 0.2 seconds or more and about 1 second or less. Is preferred.

In the present embodiment, the case where two kinds of screw members of the soft joint member and the hard joint member are tightened has been described as an example. However, as described in the first embodiment, the shut-off determination unit 10 When the proper tightening torque values of the plurality of hard joint members are set and the estimated value of the load torque reaches each of the proper tightening torques, the shut-off determining unit 10 outputs a shut-off command to the motor control unit 12. It goes without saying that the tightening operation of the soft joint member and the plurality of hard joint members having different appropriate tightening torques may be performed.

(Embodiment 3) FIG. 6 shows Embodiment 3 of the present invention.
This will be described with reference to FIG. In the present embodiment, in the power-driven rotary tool according to the second embodiment, the shutoff command based on the third threshold value is output from the shutoff determination unit 10 to the motor control unit 12.
Is set to the stop time (restart standby time) from when the motor control unit 12 temporarily stops the motor 1 in response to the shut-off command until the motor 1 is restarted. (Stop time setting unit) 15. Since the configuration other than the restart standby time setting unit 15 is the same as that of the second embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

Here, the restart standby time setting section 15 is provided with, for example, a dial-type operation knob. By rotating the operation knob, the stop time is set to a range of, for example, about 0.2 seconds or more and about 1 second or less. , Preferably about 0.25 seconds or more,
It can be changed in a range of about 1 second or less. As described above, the stop time is such a time that the operator can release the trigger switch 7 when the user wants to end the screw tightening work when the variation amount of the load torque becomes equal to or more than the third threshold value. In addition, when it is desired to complete the screw tightening operation when the load torque reaches the appropriate tightening torque of the second screw member, the waiting time until the motor 1 is restarted is not felt long. It is desirable to set the stop time to a minimum time, but since the setting of the stop time can be changed by the restart standby time setting unit 15, the stop time is set to the minimum necessary time according to the skill level of the operator. Thereby, the work time can be reduced.

In the present embodiment, a restart standby time setting unit 15 for changing the set value of the stop time is provided in the power-driven rotary tool of the second embodiment.
The power-driven rotary tool may be provided with the restart standby time setting section 15 of the present embodiment, and the same effects as described above can be obtained.

(Embodiment 4) FIG. 7 shows Embodiment 4 of the present invention.
This will be described with reference to FIG. Since the configuration of the power-driven rotary tool is the same as that of the second embodiment, a description thereof will be omitted, and only different portions will be described.

As in the second embodiment, the shut-off determination unit 10 calculates the load change amount dT calculated by the load change amount evaluation unit 11.
Is greater than or equal to a third threshold, a first shut-off command is output to the motor controller 12, and a second shut-off command is sent to the motor controller 12 when the estimated value of the load torque reaches the second threshold. Output. Shut-off determination unit 1
0, the load torque fluctuation dT obtained by the load fluctuation evaluator 11 is not greater than or equal to the third threshold (that is, the first shut-off command is not being output).
When the estimated value of the load torque estimated by the load torque estimating unit 8 reaches the second threshold value and outputs the second shut-off command, the motor is rotated only for a sufficiently short time so that an operator can recognize the rotation of the motor 1. A third shut-off command to stop after rotating 1 is output to the motor control unit 12.

Here, the shut-off determination processing will be described with reference to the flowchart of FIG. When a striking by the striking mechanism occurs, the load torque estimating unit 8 estimates the load torque applied to the driver bit 6 from the number of rotations of the motor 1 during striking and the rotating speed of the motor 1 during striking, and the shut-off determining unit 10 The output is output to the fluctuation amount evaluation unit 11 (S41 in FIG. 7). The load variation evaluator 11 obtains the load variation dT of the load torque from the estimated value of the load torque estimator 8,
Output to the shut-off determination unit 10. The shut-off determination unit 10 determines whether the first shut-off command has already been output because the load fluctuation amount dT has exceeded the third threshold value (S42 in FIG. 7), and the first shut-off is still performed. If the command has not been output, it is determined whether or not the shut-off process has already been performed because the estimated value of the load torque estimating unit 8 has reached the second threshold value (S43 in FIG. 7). Is performed, a third shut-off command to stop the motor 1 after rotating it by a predetermined amount is output to the motor control unit 12 (S46 in FIG. 7). On the other hand, if the shut-off process has not been performed, the shut-off determination unit 10 determines the load change amount dT obtained by the load change amount evaluation unit 11.
And the third threshold value (S44 in FIG. 7). When the load fluctuation amount dT is equal to or greater than the third threshold value, the first shut-off command is output to the motor control unit 12 (S4 in FIG. 7).
7). If the first shut-off command has already been output, or if the load fluctuation amount dT is less than the third threshold, the shut-off determining unit 10 determines the estimated value of the load torque estimating unit 8 and the second threshold. (S45 in FIG. 7),
When the estimated value of the load torque becomes equal to or more than the second threshold, a second shut-off command is output to the motor control unit 12 (FIG. 7).
S48).

The motor control unit 12 controls the rotation speed of the motor 1 according to the amount of pull-in of the trigger switch 7, and when a shut-off command is input from the shut-off determination unit 10, the trigger switch 7 The motor 1 is stopped irrespective of the pull-in operation. Here, when the shut-off command input from the shut-off determination unit 10 is the first shut-off command based on the third threshold, the trigger is generated from when the motor 1 is stopped until a predetermined stop time elapses. If the switch 7 is not opened, the motor control unit 12 rotates the motor 1 again when the stop time has elapsed. When the shut-off command input from the shut-off determination unit 10 is the second shut-off command based on the second threshold, the motor control unit 12 stops the motor 1 and does not restart the motor 1. On the other hand, in the motor control unit 12, when the second shut-off command is input before the first shut-off command is input, the motor control unit 12 stops the motor 1 until the predetermined stop time elapses. If the trigger switch 7 is not opened during this time, the motor control unit 12 rotates the motor 1 for a predetermined time after the stop time has elapsed, and then stops the motor 1 to end the screw tightening operation.

By the way, depending on the type of the screw member and the design of the combination thereof, the estimated value of the load torque reaches the second threshold value and the second May be output in some cases. In such a case, since the load torque reaches the appropriate tightening torque just by stopping the motor 1 once, the number of times the motor 1 stops before reaching the appropriate tightening torque becomes smaller than the number of times expected by the operator. The operator may not know whether the screw tightening operation has been completed with the proper tightening torque of the first screw member or the screw tightening operation has been completed with the proper tightening torque of the second screw member.

On the other hand, in the present embodiment, when the second shut-off command is input before the first shut-off command is input, the motor 1 is stopped for a predetermined stop time. If the trigger switch 7 is not opened before the time elapses, the motor control unit 12 rotates the motor 1 for a predetermined time when the stop time elapses,
Since the motor 1 is stopped, the number of times the motor 1 stops until the tightening torque reaches the appropriate tightening torque of the second screw member can be increased by one, and can be adjusted to two times. The operator can be informed that the screw member has been tightened with the proper tightening torque of the screw member. Further, since the amount of rotation of the motor 1 by the third shut-off command is sufficiently small, the tightening torque accuracy is not greatly deteriorated by this.

FIG. 8 shows the estimated torque T of the load torque estimating section 8 and the load fluctuation amount estimating section 11 which change with the progress of the screw tightening operation (ie, the number of hits N by the hammer 3).
At the time point P2 when the load fluctuation amount dT becomes equal to or more than the third threshold value Tb, the shut-off determination unit 10 issues a first shut-off command to the motor control unit 12.
And the motor control unit 12 stops the motor 1 for a predetermined stop time. If the trigger switch 7 is not opened before the stop time elapses, the motor control unit 12 restarts the rotation of the motor 1 after the stop time elapses, and the estimated torque T of the load torque Threshold T of 2
a, at time P1, the shut-off determination unit 10
Is output to the motor control unit 12, and the motor control unit 12 stops the motor 1.

[0053]

As described above, according to the first aspect of the present invention, there is provided a power-driven rotary tool used for tightening and loosening a plurality of types of screw members having different proper tightening torques. An output shaft, a drive unit for rotating the output shaft, a trigger switch for generating an operation signal according to the retracted amount, and a drive control unit for controlling the rotation speed of the drive unit according to the operation signal input from the trigger switch And a load torque estimating unit for estimating the load torque applied to the output shaft, and a stop command for stopping the driving unit is sent to the drive control unit every time the estimated value of the load torque estimating unit reaches the appropriate tightening torque of each screw member. And a drive control unit that stops the drive unit regardless of an operation signal of the trigger switch when a stop command is input from the shut-off determination unit,
If the trigger switch is not released between the time when the drive unit is stopped and the predetermined stop time elapses, the drive unit is rotated again when the stop time elapses. Outputs a stop command to the drive control unit when the appropriate tightening torque of each screw member is reached, and the drive control unit stops the drive unit for a predetermined stop time when the stop command is input. If the trigger switch is released during this time, the load torque can be set to the appropriate tightening torque at this time. On the other hand, if the trigger switch is continued to be pulled during the elapse of the stop time, the drive control unit restarts the rotation of the drive unit, and when the load torque reaches the appropriate tightening torque, the drive control unit receives the input from the shut-off determination unit. Since the drive unit is stopped by the stop command, the screw member can be tightened to the desired proper tightening torque by opening the trigger switch when the load torque reaches the desired proper tightening torque, and the drive unit The current tightening torque can be ascertained from the number of times the motor is stopped. Therefore, it is possible to efficiently perform the screw tightening operation of a plurality of screw members having different tightening torques without performing the tightening torque setting operation, and set the tightening torque as in the conventional power-driven rotary tool. Since a torque setting device is not required,
There is an effect that the power-driven rotary tool can be reduced in size and cost.

According to a second aspect of the present invention, in the first aspect of the present invention, a load variation detecting section for detecting a variation of the estimated value of the load torque estimating section per predetermined time is provided. When the fluctuation amount detected by the amount detection unit becomes equal to or more than a predetermined threshold value, a stop command is first output to the drive control unit, and when a screwing operation of a soft joint member such as a resin grommet is performed, a seating is performed. Immediately after the screw tightening operation is completed, the tightening torque becomes an appropriate value.However, the shut-off determination unit first issues a stop command when the variation detected by the load variation detection unit exceeds a predetermined threshold. Since the output is output, if the trigger switch is opened at the time when the drive unit is first stopped by the drive control unit, at the time when the fluctuation amount of the load torque sharply increases, that is, at the time when the screw member is seated. It is possible to stop the dynamic portion, there is an effect that allows the screwing operation of the soft joint member at the appropriate tightening torque.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the stop time is approximately 0.2 seconds or more and approximately 1 second or less. When the screw tightening work is completed at the time when the time has reached, the driving unit is restarted when it is time to secure enough time for the operator to release the trigger switch and when the screw tightening work is to be continued. It is desirable to set the waiting time until the user does not feel long, and the stop time is preferably about 0.2 seconds or more and about 1 second or less.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, a stop time setting unit for changing a set value of the stop time is provided. The drive unit is restarted when it is time to allow the operator to release the trigger switch when the screw tightening work is to be terminated when the torque is reached, and when the screw tightening work is to be continued. It is desirable to set the waiting time until the user does not feel long, and there is an effect that the stopping time can be set to a desired time by the stopping time setting unit.

According to a fifth aspect of the present invention, in the second aspect of the present invention, when the variation detected by the load variation detecting section is not equal to or larger than the threshold value, the estimated value of the load torque estimating section is set to a desired value. When the stop torque is reached and a stop command is input from the shut-off determination unit to the drive control unit, the drive control unit stops the drive unit regardless of the operation signal of the trigger switch, and then stops the drive unit. If the trigger switch is not opened before the stop time elapses, after the stop time elapses, the drive unit is rotated for a sufficiently short time so that an operator can recognize the rotation of the drive unit, and then the drive unit is rotated. Depending on the type of screw member and the design of the combination thereof, the estimated value of the load torque estimating unit may be reduced when the variation detected by the load variation detecting unit does not exceed the threshold. Screw part In this case, the number of times the drive unit stops until the desired appropriate tightening torque is reached is reduced by one time from the number expected by the operator, and the desired torque can be obtained. The operator may not know whether the screw tightening operation has been completed or not, but when the variation detected by the load variation detecting unit does not exceed the threshold, the estimated value of the load torque If the stop torque is reached and a stop command is input from the shut-off determination unit to the drive control unit, the trigger switch must be opened between a time when the drive unit is stopped and a predetermined stop time elapses. When the stop time has elapsed, the drive control unit rotates the drive unit for a predetermined time and then stops, so the number of times the drive unit stops until the tightening torque reaches the desired appropriate tightening torque is determined. 1 Since it can be corrected by increasing the amount, the operator can be informed that the screw member has been tightened with a desired appropriate tightening torque, and in this case, the rotation amount of the drive unit rotated by the drive control unit is Since it is sufficiently small, the tightening torque accuracy does not greatly deteriorate.

[Brief description of the drawings]

FIG. 1 is a block diagram of an impact rotary tool according to a first embodiment.

FIG. 2 is a flowchart illustrating the operation of the above.

FIG. 3 is a flowchart illustrating another operation of the above embodiment.

FIG. 4 is a block diagram of an impact rotary tool according to a second embodiment.

FIG. 5 is a flowchart illustrating the operation of the above.

FIG. 6 is a block diagram of an impact rotary tool according to a third embodiment.

FIG. 7 is a flowchart illustrating an operation of the impact rotary tool according to the fourth embodiment.

FIG. 8 is an explanatory diagram illustrating a relationship between the number of hits and torque in the above.

FIG. 9 is a block diagram of a conventional impact rotary tool.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 6 Output shaft 7 Trigger switch 8 Load torque estimation unit 10 Shut-off determination unit 12 Motor control unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor ▲ Matsu ▼ Moto Tatsuhiko 1048 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Works, Ltd. (72) Minoru Yoshida 1048 Kadoma Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works F term within the company (reference) 3C038 AA01 BC04 CA06 CB02 CC04 CC06 EA06

Claims (5)

[Claims] An output shaft for tightening and loosening a screw member and a drive for rotating the output shaft in a power-driven rotary tool used for tightening and loosening a plurality of types of screw members having different proper tightening torques. Unit, a trigger switch that generates an operation signal according to the amount of pull-in, a drive control unit that controls the rotation speed of the drive unit according to the operation signal input from the trigger switch, and a load torque applied to the output shaft. And a shut-off determination that outputs a stop command to stop the drive unit to the drive control unit each time the estimated value of the load torque estimation unit reaches an appropriate tightening torque of each screw member. The drive control unit, when a stop command is input from the shut-off determination unit, stops the drive unit regardless of the operation signal of the trigger switch, the drive control unit If the trigger switch is not opened before the predetermined stop time elapses after the stop, the drive unit is rotated again when the stop time elapses. 2. A load fluctuation detecting section for detecting a fluctuation amount per predetermined time of an estimated value of the load torque estimating section, wherein the shut-off determining section detects a fluctuation amount detected by the load fluctuation detecting section. The power-driven rotary tool according to claim 1, wherein the stop command is first output to a drive control unit when the stop command is equal to or greater than a predetermined threshold value. 3. The power-driven rotary tool according to claim 1, wherein the stop time is about 0.2 second or more and about 1 second or less. 4. The power-driven rotary tool according to claim 1, further comprising a stop time setting section for changing a set value of the stop time. 5. When the variation detected by the load variation detecting section does not exceed the threshold, the estimated value of the load torque estimating section reaches a desired appropriate tightening torque, and When a stop command is input from the OFF determination unit to the drive control unit, the drive control unit stops the drive unit irrespective of the operation signal of the trigger switch, and the stop time after stopping the drive unit If the trigger switch is not opened before elapse, at the time when the stop time elapses, after rotating the driving unit for a sufficiently short time so that an operator can recognize the rotation of the driving unit, The driving unit is stopped.
A power-driven rotary tool as described.