JPH09285974A - Impact wrench fastening controlling method and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily detect an advance quantity of a rotation angle in every impact of an anvil by obtaining a signal necessary for fastening force control from a part, to which an impact force or a reaction rotation force is applied not so much, other than the anvil or the intermediate part between the anvil and a socket. SOLUTION: An impact sensor 15, which detects release of engaging teeth 11T, 11T of a hammer 11 from engaging teeth 13T, 13T of an anvil 13 when the hammer 11 is pressed backward, is installed on a case body 1A side to which an impact force or a reaction rotational force is not directly applied from the hammer 11 or the anvil 13. According to respective detection signals fed from a rotary encoder 4 and the impact sensor 15, a rotation angle of an electric motor 2 is computed by means of a rotation angle computing means every time when an impact force is generated once. When this rotation angle reaches the predetermined rotation angle or less, a supply power source for the electric motor 2 is cut off and fastening is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of an impact wrench that tightens bolts by using impact force (impact force), and more specifically, a method for controlling impact wrench tightening. And the device.

[0002]

2. Description of the Related Art A conventional general impact wrench engages a hammer, which is under the urging force of a spring, with an anvil equipped with a socket for tightening bolts. By rotating the anvil in conjunction with it, when the tightening reaction force (load) of the bolt becomes larger than the spring biasing force of the hammer, the hammer is separated from the anvil and once in a free rotation state, the next moment Is again engaged with the anvil by a spring biasing force, and a strong impact force at the time of engagement is used to rotate the anvil to tighten the bolt.

In such an impact wrench, in order to accurately control the tightening torque, it is necessary to accurately control the impact with the impact wrench, but the time control or the number of impacts which have been conventionally used is required. In the control method called control, the tightening force can only be roughly adjusted, and sufficient tightening accuracy cannot be obtained.

Therefore, in order to obtain a sufficient tightening accuracy, a strain detector for detecting a tightening torque as shown in, for example, Japanese Patent Laid-Open No. 57-114370 is provided in the anvil or an intermediate portion between the anvil and the socket. Or, similarly, JP-A-59
-53168, there is provided a reaction rotation amount detector for detecting a reaction rotation amount after impact, and further, a rotation angle of a nut for each impact as seen in JP-A-7-308866. A rotation angle detector for detecting the torque is provided, and the tightening force is controlled according to the detection signals sent from these detectors.

[0005]

However, in the detection at the anvil or the intermediate portion between the anvil and the socket, the impact force and the reaction rotational force complicately act, and the acceleration change is severe.
It is not possible to use a high-precision detector (such as a rotary encoder), and the detected signal must be subjected to complicated correction processing in order to match the actual tightening force. There has been a problem that the control device is increased in size and cost is increased.

Therefore, the technical problem of the present invention is to obtain a signal necessary for controlling the tightening force from a portion other than the anvil or an intermediate portion between the anvil and the socket to which impact force or reaction rotational force is not applied so much. That is, it is possible to easily and accurately detect the advance amount of the rotation angle for each impact of the anvil without performing correction processing.

[0007]

[Means for Solving the Problems] Means taken in the present invention for solving the above technical problems are as follows.

By engaging a hammer on the electric motor side with an anvil equipped with a socket for tightening bolts, the rotation of the electric motor is transmitted to the anvil side. Disengaged,
In the impact wrench configured to perform bolt tightening by using the impact force when the hammer meshes with the anvil again by the biasing force of the spring,

(1) Each time the impact force of the hammer is exerted, the rotation angle of the electric motor or the interlocking mechanism provided between the electric motor and the hammer is measured, and this rotation angle is less than the set rotation angle. When it reaches, the power supply to the electric motor should be cut off to stop the rotation of the anvil.

(2) An impact sensor for detecting the detachment of the hammer from the anvil, and a rotation angle detection sensor for detecting the rotation angle of the electric motor or the interlocking mechanism provided between the electric motor and the hammer. A rotation angle calculating means for calculating a rotation angle of the electric motor or the interlocking mechanism each time an impact force is generated once according to detection signals sent from these sensors, and the calculated rotation angle is equal to or less than a set rotation angle. And an anvil rotation stopping means for stopping the rotation of the anvil by cutting off the power supply to the electric motor.

(3) An impact sensor for detecting that the hammer has separated from the anvil, and a rotation angle detection sensor for detecting the rotation angle of the electric motor or the interlocking mechanism provided between the electric motor and the hammer. A rotation angle difference calculating means for calculating the rotation angle of the electric motor or the interlocking mechanism each time an impact force is generated once according to the detection signals sent from these sensors, and the calculated rotation angle for each impact. The anvil advance amount conversion means for converting the advance amount of the rotation angle of the anvil and the changed anvil rotation angle advance amount and the set value set by the anvil advance amount setting means are compared, and the advance amount becomes equal to or less than the set value. An anvil advance amount comparison means for determining whether or not the anvil has reached, and an anvil that stops the rotation of the anvil by cutting off the power supply to the electric motor when the advance amount reaches a set value or less. Building rotation stop means.

(4) The anvil rotation stopping means is provided with a brake circuit for immediately stopping the supply of power to the electric motor and applying a brake to the rotation of the electric motor to immediately stop the rotation of the anvil.

According to the means (method) described in the above (1), it is provided between the electric motor or the electric motor to which the strong impact force or the reaction rotational force at the time of tightening the bolt does not directly act. Since the rotation angle of the interlocking mechanism is measured and the tightening force is controlled based on the measured rotation angle, the advance amount of the rotation angle for each impact of the anvil can be accurately known.
It enables the use of high-precision detectors such as rotary encoders, and enhances the reliability of tightening force control.

According to the means (apparatus) described in the above (2), the rotation angle calculation means generates the impact force (striking force) once according to the detection signals sent from the impact sensor and the rotation angle detection sensor. The rotation angle of each electric motor or interlocking mechanism is calculated, and the hammer is repeatedly hit with the anvil until this rotation angle reaches a preset value or less, so the bolts can be securely tightened. The sensor can also be provided at a portion to which impact force or reaction torque is not applied so much, so that it is possible to use the detected signal as it is without correction processing.

According to the means (apparatus) described in the above (3), by measuring the rotation angle of the electric motor or the interlocking mechanism from the occurrence of impact to the next impact, the advance of the rotation angle at one impact of the anvil. When the amount of advance is less than the planned rotation angle, the power supply to the electric motor is cut off and the rotation of the anvil is stopped, so the bolt can be tightened to a predetermined strength and the impact Both the sensor and the rotation angle detection sensor can be installed on the part other than the anvil or the intermediate part between the anvil and the socket where impact force or reaction rotational force is not applied so much, so the detection signal can be used without modification To be able to do.

According to the means (apparatus) described in the above (4), the brake circuit applies the brake to the rotation of the electric motor to immediately stop the rotation of the anvil, so that the inertial rotation of the anvil is controlled to waste the bolt. It is possible to reduce the number of hits.

As described above, the above (1) to (1)
By the means described in (4), it is possible to solve the above-mentioned technical problems and solve the problems of the conventional techniques.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The above-described embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a partial cross-sectional front view illustrating the internal structure of an impact wrench provided with a tightening control device according to the present invention. An electric motor 2 is attached, and a rotary encoder 4 for measuring the rotation angle of the electric motor 2 is attached to the outside of the root end of the case body 1A via a coupling 3.

Reference numeral 5 is an output shaft of the motor 2, 6 is a cooling fan attached to the output shaft 5, and 7 and 7 are motor output shafts 5.
A gear portion 5A formed at the front end of the gear, which rotates in an interlocking manner, 7A and 7A are left and right reduction gear shafts, 8 is a ring gear with internal teeth which mesh with these both reduction gears 7, 7, and 9 is a root end Is a spindle whose parts are attached to the left and right reduction gear shafts 7A, 7A, and when the output shaft 5 of the electric motor 2 rotates,
The spindle 9 is designed to be rotated at a reduced speed.

Reference numeral 11 denotes a hammer attached to the outer periphery of the tip end portion 9A of the spindle 9 projecting in the inner axis direction of the case body 1A, and also slidably attached in the axial direction, and 11S fitted to the root end portion of the spindle 9. A compression spring interposed between the cup-shaped spring seat 10 and the inner bottom portion of the outer cylindrical body 11A continuously provided on the root end side of the hammer 11;
Reference numerals 12 and 12 denote steel balls fitted in spiral grooves 9X, 9X recessed on the outer peripheral surface of the spindle tip portion 9A, and the hammer 11 is always the tip opening of the case body 1A by the elastic force of the compression spring 11S. It is urged in the direction 1B (downward direction in the drawing).

11T and 11T are engaging teeth protruding from the tip of the hammer 11, 13 is an anvil slidably fitted in the tip opening 1B of the case body 1A, and 13T and 13T are inner surfaces of the tip opening 1B. The engaging teeth formed on the root end portion of the anvil 13 fitted in the socket 14 are sockets that are attached to the tip portion 13A of the anvil 13 protruding outside the tip opening 1B so as to be exchangeable by using a holder 14A. The engaging teeth 13T, 13T of the anvil 13 can be meshed with the engaging teeth 11T, 11T of the hammer 11, and the heads of the bolts Z to be attached to the various members R fit inside the socket 14. It is configured to be plugged in freely.

FIG. 2 shows the engaging teeth 11 of the hammer 11 and anvil 13 based on the urging force of the compression spring 11S described above.
FIG. 11 is a cross-sectional view showing a state in which the rotation of the electric motor 2 is transmitted to the socket 14 via the anvil 13 and the bolt Z is screw-rotated by the engagement of T, 11T and 13T, 13T.

Further, in FIG. 3, the above-mentioned screw rotation advances and the tightening force increases, and the reaction force that pushes the anvil 13 backward (upward in the drawing) is the compression spring 11 described above.
A cross-sectional view showing a state in which the spring pressure becomes larger than S, and as a result, the hammer 11 is pushed backward to disengage the engaging teeth 11T, 11T of the hammer 11 from the engaging teeth 13T, 13T of the anvil 13. 2 and 3 and FIG. 1
15 detects the outer cylindrical body 11A of the hammer 11 pushed backward and detects the engaging teeth 11T, 11T and 13
The impact sensor 15 for detecting the disengagement of the engagement of T and 13T is shown in FIG.
It is mounted on the side of the case body 1A that does not directly receive the impact force or reaction torque of the anvil 13.

When the hammer 11 is pushed backward and the engagement teeth 11T, 11T and 13T, 13T are disengaged from each other as described above, the hammer 11 is temporarily released from the load of the anvil 13. At the moment of, the compression spring 11
Since it is elastically urged forward (downward in the drawing) by the urging force of S, this elastic force causes the engaging teeth 11 of the hammer 11 to move.
T and 11T can hit the engaging teeth 13T and 13T of the anvil 13 to generate a strong impact force that tightens the bolt Z on the anvil 13 side.

According to the present invention, the impact sensor 15 detects the outer cylinder 11A of the hammer 11 until the next detection, that is, between the impact force generation and the next impact force generation. When the rotation angle of the electric motor 2 reaches a preset rotation angle or less, the power supply to the electric motor 2 is cut off to stop the tightening (claims 1 and 2), or the electric motor 2 is rotated. Rotation angle is further 1 of anvil 13
It is configured to be converted into the advance amount of the rotation angle at impact, and when the advance amount reaches a predetermined rotation angle or less, the power supply to the electric motor 2 is cut off to stop the tightening (claim 3).

In short, assuming that the anvil 13 does not rotate, the hammer 11 repeats hitting the anvil 13 once every 180 ° rotation, and in the case of bolting, the anvil 13 is gradually rotated by the hammer 11 hitting. Therefore, the rotation angle is 180 ° + α.

On the other hand, since the rotations of the electric motor 2 and the hammer 11 are determined by the speed reducer, the hammer 11 moves 180 degrees.
° You can know the rotation of the electric motor 2 when rotating,
If you read it with the signal from the rotary encoder 4,
Since the anvil 13 has rotated more than 180 °, the power supply to the electric motor 2 is cut off when this amount of rotation reaches or falls below the planned (set) amount of rotation, and the brake circuit is used. Immediately stop the rotation of the anvil 13,
It is designed to prevent excessive impact.

FIG. 4 is a block diagram for explaining the electrical construction of the tightening control device according to the present invention. In the figure, 20 is a controller equipped with a microcomputer, 21 is a power switch and for forward rotation and reverse rotation. Operation switch equipped with each switch, 22 is a volume for setting the rotation angle of the anvil 13 in one impact, 23 is an SSR relay, 2
Reference numeral 4 represents a relay circuit including forward and reverse relays and a brake relay.

A memory (not shown) incorporated in the controller 20 is sent from the respective means described in the claims and the overall configuration diagram of FIG. 7, that is, the rotary encoder 4 and the impact sensor 15. Rotation angle calculation means for calculating the rotation angle of the electric motor 2 each time an impact force is generated once according to each incoming detection signal, and an anvil for converting the calculated rotation angle into the advance amount of the rotation angle of the anvil for each impact. The advance amount conversion means, the converted anvil rotation angle advance amount and the set value are respectively compared to determine whether or not the advance amount has reached the set value or less, and the advance amount comparison means and the advance amount are set values. Various programs are stored for configuring an anvil rotation stopping means for cutting off the power supply to the electric motor 2 when the following is reached.

FIG. 5 is a diagram showing the relationship between the number of signals from the rotary encoder 4 between impacts and the rotary encoder signal and the impact sensor signal.
FIG. 6 is a flow chart for explaining each processing procedure of bolt tightening and loosening according to the present invention, and FIG. 7 is a configuration diagram for explaining the whole of the present invention. Step S1 in executing the flow chart shown in FIG. When the tightening rotation process (normal rotation switch ON) is selected, the bolt tightening process up to step S10 is executed according to the program stored in the memory, and the loosening rotation process (reverse rotation switch ON) in step S11 of the flowchart is selected. In this case, the bolt loosening process from step S12 to step S17 is executed according to the memory program.

In the above description of the embodiment, the rotation angle of the electric motor 2 is measured by the rotary encoder 4. However, an intermediate interlocking mechanism (reduction gear etc.) for transmitting the rotation of the electric motor 2 to the hammer 11 side. Since the same effect can be obtained even if the rotation of (1) is measured by the rotary encoder 4, the measurement position may be any as long as it is not subjected to the reaction rotation due to the impact.

[0033]

As described above, according to the present invention, it is possible to automatically perform the tightening work with the prescribed bolt tightening force without depending on the feeling of the worker, and the variation in the bolt tightening force can be achieved even for a beginner. Although it is possible to perform an appropriate bolt fastening work without causing the occurrence, particularly in the present invention, since the rotation angle of the electric motor or the interlocking mechanism is detected in a portion that is not subjected to impact force or reaction rotational force, high precision such as a rotary encoder is required. Since the sensor can be used to accurately detect the rotation angle and correction of the detected rotation angle is not necessary, it has an advantage that the rotation angle can be implemented at a relatively low cost.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional front view illustrating the internal structure of an impact wrench including a tightening control device according to the present invention.

FIG. 2 is a cross-sectional view of an essential part for explaining a state where a hammer and an anvil are meshed with each other.

FIG. 3 is a cross-sectional view of an essential part for explaining a state where a hammer and an anvil are separated from each other.

FIG. 4 is a block diagram illustrating an electrical configuration of a tightening control device according to the present invention.

FIG. 5 is a diagram illustrating the relationship between the number of signals of the rotary encoder, the rotary encoder signal, and the impact sensor signal.

FIG. 6 is a flowchart illustrating each processing procedure of bolt tightening work and loosening work.

FIG. 7 is a configuration diagram illustrating the entire invention.

[Explanation of symbols]

 1 Impact Wrench 1A Case Body 2 Electric Motor 4 Rotary Encoder 5 Motor Output Shaft 7 Reduction Gear 9 Spindle 11 Hammer 11T Engaging Teeth 11S Compression Spring 13 Anvil 13T Engaging Teeth 14 Socket 15 Impact Sensor Z Bolt

Claims (4)

[Claims] 1. A rotation of an electric motor is transmitted to the anvil side by engaging a hammer on the side of the electric motor with an anvil equipped with a socket for tightening bolts, while an excessive load is applied to the anvil side. In the impact wrench configured to disengage the hammer and use the impact force when the hammer meshes with the anvil by the biasing force of the spring to tighten the bolts, the impact force of the hammer is exerted. Every time, the rotation angle of the electric motor or the interlocking mechanism provided between the electric motor and the hammer is measured, and when this rotation angle reaches the set rotation angle or less, the power supply to the electric motor is cut off and the anvil A tightening control method for an impact wrench, characterized by stopping rotation. 2. The rotation of the electric motor is transmitted to the anvil side by engaging a hammer on the side of the electric motor with an anvil equipped with a socket for tightening bolts, while an excessive load is applied to the anvil side. In the impact wrench configured to disengage the hammer and use the impact force when the hammer again meshes with the anvil by the biasing force of the spring to tighten the bolt, the hammer is disengaged from the anvil. Impact sensor that detects the rotation angle, the rotation angle detection sensor that detects the rotation angle of the electric motor or the interlocking mechanism provided between the electric motor and the hammer, and the impact force according to the detection signals sent from these sensors. Angle calculating means for calculating the rotation angle of the electric motor or the interlocking mechanism each time the occurrence of Upon reaching the lower clamping control apparatus of the impact wrench, characterized by being configured by an anvil rotation stopping means for stopping the rotation of the anvil turned down power supply to the electric motor. 3. The rotation of the electric motor is transmitted to the anvil side by engaging a hammer on the side of the electric motor with an anvil equipped with a socket for tightening bolts, while an unnecessarily large load is applied to the anvil side. In the impact wrench configured to disengage the hammer and use the impact force when the hammer again meshes with the anvil by the biasing force of the spring to tighten the bolt, the hammer is disengaged from the anvil. Impact sensor that detects the rotation angle, the rotation angle detection sensor that detects the rotation angle of the electric motor or the interlocking mechanism provided between the electric motor and the hammer, and the impact force according to the detection signals sent from these sensors. Angle difference calculation means for calculating the rotation angle of the electric motor or the interlocking mechanism each time the occurrence of An anvil advancing amount conversion means for converting the advance amount of the rotation angle of the anvil for each,
The anvil advance amount comparison means for comparing the changed anvil rotation angle advance amount with the set value set by the anvil advance amount setting means to determine whether or not this advance amount has reached the set value or less, and the advance amount. Is a set value or less, the impact wrench tightening control device is constituted by an anvil rotation stop means for stopping the rotation of the anvil by cutting off the power supply to the electric motor. 4. An anvil rotation stopping means is provided with a brake circuit for stopping the supply of power to the electric motor and applying a brake to the rotation of the electric motor to immediately stop the rotation of the anvil. The impact wrench tightening control device according to 2 or 3.