JP2001121442A - Impact tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability and safety at the time of loosening work, in this invention. SOLUTION: A detection means 5 of ending of rotational impact action, for detecting the ending of the rotational impact action based on an output from a detection means 4 of the rotational impact action at the time of loosening operation, is provided, also a switching means 6, for stopping a motor 2 by an output from the detection means 4 of ending of rotational impact action, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact tool such as an impact wrench or an impact driver used for tightening or loosening bolts, nuts or screws, which are members to be tightened. The present invention relates to a circuit configuration for controlling the rotation impact operation at the time.

[0002]

2. Description of the Related Art Conventionally, an impact tool such as an impact wrench or an impact driver has been used at the time of tightening or loosening a bolt, a nut, or a screw as a member to be tightened.

For example, a conventional impact tool is rotatable via a steel ball on a gear mechanism (reduction mechanism) for transmitting the rotational power of a motor as a drive source, and a rotating shaft rotated by an output from the gear mechanism. A hammer movable in the axial direction of the rotating shaft, and a striking mechanism comprising an anvil having a wing portion struck and rotated by a plurality of claws provided on the hammer; and a main switch for controlling power supply to the motor. And the like. A battery for supplying electric power to the motor is detachably provided at one end of a handle portion formed by the housing.

When using such an impact tool, first, a main switch is operated to supply electric power to the motor while a nut or the like is fitted to one end of the anvil. The rotating power of the motor supplied with power is transmitted to the rotating shaft after being reduced by the gear mechanism, and is transmitted to the rotating shaft via a steel ball to the rotatable hammer that can move in the axial direction. Is done. The hammer is provided with a plurality of claws, and when the claws periodically collide with the blades provided on the anvil, a striking force is imparted to the rotating anvil, whereby the nut is provided. Tightening.

When the nut is loosened, a forward / reverse switch for switching the rotation direction of the motor is operated.
After that, by operating the main switch with the nut fitted to one end of the anvil as in the tightening work,
The nut is loosened while applying a rotational impact to the anvil, and finally the nut is loosened only by rotation without imparting an impact.

[0006]

When a bolt, a nut or a screw is loosened using a conventional impact wrench or impact driver, the main switch is turned on with the nut or the like fitted to one end of the anvil. Since the nut is loosened while operating and applying a rotary impact force to the anvil, when the nut or the like is loosened to some extent, the claw portion of the hammer and the blade portion of the anvil rotate integrally while abutting. For this reason, the rotation hitting operation of the anvil is eliminated, and the rotation speed of the rotary shaft is increased to reduce the load on the motor. In such a state, for example, when the engagement length (the number of screw grooves) between the nut and the bolt is short (small), the nut is detached from the bolt before the operator stops the rotation of the impact tool motor. There was a problem that it would. In particular, when the nut or the like falls during the loosening work at a high place, there is a problem that the workability and safety are impaired, and the nut and the like are also lost.

An object of the present invention is to solve the above problem and improve workability and safety during loosening work.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor as a drive source, a gear mechanism for transmitting rotational power of the motor, and a rotatable and axially movable rotary shaft which is rotated by an output from the gear mechanism. A rotary hammer detecting means for detecting a rotary hammer between the claw and the blade, the hammer being provided so as to be capable of being rotated, and an anvil having a wing portion which is rotated by being hit by a plurality of claw portions provided on the hammer. In the impact tool having: and a rotary impact operation end detecting means for detecting the end of the rotational impact operation based on the output from the rotational impact operation detecting means at the time of the loosening operation, and the output from the rotational impact operation end detecting means This is achieved by providing switching means for stopping the motor.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an impact tool according to the present embodiment will be described with reference to FIGS. FIG. 1 is a block circuit diagram showing a control circuit of the impact tool according to the present embodiment, FIG. 2 is a longitudinal sectional side view showing the impact tool according to the present embodiment, and FIG. FIG. 4 is a view showing the positional relationship between the claw portion 32 of the hammer and the blade portion 31 of the anvil, as viewed in the direction of the arrow A in FIG. 2, FIG. 4 is a flowchart showing automatic stop control during loosening work according to this embodiment, and FIG. Claw part 32 at the time of rotary impact operation in the embodiment
FIG. 6 is a waveform diagram showing a rotation hitting operation detection signal at the time of a rotary hitting operation according to the present embodiment, and FIG. 7 is another state diagram at the time of a loosening operation according to the present embodiment. It is a flowchart which shows automatic stop control.

The impact tool shown in FIGS. 2 and 3 has a gear mechanism 21 for transmitting the rotational power of a motor 2 as a drive source.
(A deceleration mechanism), a hammer 23 rotatable via a steel ball on a rotating shaft that is rotated by an output from the gear mechanism unit 21, and a plurality of claws provided on the hammer 23. And a control circuit board 25 disposed at the rear of the motor 2 and mounted with a microcomputer 5 (hereinafter referred to as a microcomputer) and the like. , A main switch 3 for controlling the power supply to the motor 2, etc., and a battery for supplying power to the motor 2 is provided at one end of a handle portion formed by the housing 24. 1 is provided detachably.

When using such an impact tool, first, the main switch 3 is mounted in a state where bolts, nuts, screws, etc., which are members to be tightened, are fitted to one end of the anvil.
To supply electric power to the motor 2. The rotating power of the motor 2 to which the electric power is supplied is reduced by the gear mechanism 21 and transmitted to the rotating shaft, and the hammer is rotatable and axially movable on the rotating shaft via a steel ball. 23. The hammer 23 has a plurality of claw portions 32.
When the claw portion 32 periodically collides with the blade portion 31 provided on the anvil 22, a striking force (rotational impact torque) is applied to the rotating anvil 22. The tightened member is tightened.

When the member to be tightened is loosened, the forward / reverse switch 7 for switching the rotation direction of the motor 2 is operated, and then the nut is fitted to one end of the anvil 22 as in the case of the tightening operation. By operating the main switch 3 in this state, the nut is loosened while applying a rotational impact force to the anvil 22, and finally the tightened member is loosened only by rotation without imparting an impact force.

Next, a control circuit of the impact tool according to the present embodiment will be described with reference to FIG. 1, and an automatic stop control at the time of loosening operation by this control circuit will be described with reference to FIG.

In FIG. 1, 1 is a battery 1, 2 is a motor 2, 3 is a main switch for supplying electric power to the motor 2, 4 is a rotary hitting operation detecting means for detecting a rotary hitting operation, and 5 is a rotary hitting operation. A microcomputer serving as a rotary impact operation end detecting means for detecting the end of the rotary impact operation based on the output from the detecting means 4.
Switching means for interrupting power supply to the motor 2 and stopping the motor 2; 7 a forward / reverse switch for switching between forward and reverse rotation of the motor 2; and 8 a forward / reverse rotation for distinguishing between forward and reverse rotation of the motor 2. It is a determining means. Here, the rotation impact operation detecting means 4 detects the rotation impact operation based on a change in the current of the motor 2.
Any device may be used as long as it can be detected by a change in the output shaft torque, by an impact during a rotary impact operation, or by a rotary encoder or the like that can detect a change in the number of revolutions of the motor 2 during a rotary impact operation.

With such a control circuit, when the operator pulls the main switch 3, the switching means 6 is turned on, power is supplied to the motor 2, and the impact tool is started. At the same time, power is also supplied to the microcomputer 5 and the microcomputer 5 is started. Next, the rotational direction is determined from the output of the forward / reverse determining means 8, and if it is the reverse rotation, that is, the loosening operation, automatic stop control is performed (step 41). Immediately after the impact tool starts to operate, since the motor 2 does not reach the torque at which the rotary impact operation can be performed, the impact tool is in a locked state. The rotation hitting operation is not detected (step 42). When the impact tool starts the rotary impact operation, a rotary impact operation detection signal is output from the rotary impact operation detecting means 4 (step 43).

Here, the claws 32 of the hammer 23 shown in FIG.
The output signal of the rotation hitting operation detection signal generated by the collision between the motor and the blade 31 of the anvil 22 will be described with reference to FIGS. 5 and 6. FIG. 5 is a schematic diagram in which the rotary striking operation of the claw portion 32 and the blade portion 31 shown in FIG. 3 is developed from 0 to 180 °. In a normal rotary striking operation, the claw portion 32 is moved to the position shown in FIG. As shown in the figure, since a fixed trajectory is drawn and collides with the blade 31 of the anvil 22, the rotation hit detection signal generates the first output once for each hit operation as shown in FIG. As a result, the period T is constant. However, depending on the type of tightening member, nut or screw,
For example, as shown in FIG. 5B, when the claws 32 and the blades collide with each other, the claws 32 and the blades may collide with each other many times (two times), whereby the trajectory of the claws is described above. Since the trajectory is different from the normal trajectory, the first and second outputs are generated for each rotation hitting operation as a rotation hit detection signal as shown in FIG. 6B. As a result, there is a problem that two output signals are generated within the period T.

Therefore, in this embodiment, in order to solve the above-mentioned problem, the rotation hitting operation is detected after the rotation hitting operation is detected so that an output signal outside the rotation hitting cycle (the second output signal) is not detected when the rotation hitting operation is detected. Dead time t shorter than cycle T
And only the output signal generated by the original rotary impact operation is detected by masking (step 44). When the loosened load of the tightened member is reduced and the rotation impact operation of the impact tool is completed, the output from the rotation impact operation detecting means 4 is stopped, and after the dead time t has elapsed, the rotation impact operation is detected in the rotation impact operation detection step 43. If the signal is not input by the time exceeding the rotation hitting operation detection time τ shown in FIG. 6A, it is determined that the rotation hitting operation has been completed (step 4).
5). When it is determined that the rotary impact operation has been completed, the power supply to the motor 2 is cut off by the switching means 6, and the motor 2 is stopped (step 46). Finally, the operator operates (opens) the main switch 3 to complete the loosening operation. At the time of normal rotation, that is, at the time of the tightening operation, no control is performed until the main switch 3 is released, or the control waits, or the tightening torque is controlled based on the rotation impact amount (step 4).
7).

Another embodiment of the automatic stop control during the loosening operation will be described with reference to FIG. FIG. 7 shows a control circuit to which brake control is added when the motor 2 is stopped. By applying a brake when the motor 2 is stopped, the time until the motor 2 stops can be further shortened than when no brake is applied. Therefore, even when the fitting length (the number of screw grooves) of the bolt and nut is short (the number of thread grooves) is small, the rotation impact operation of the impact tool can be stopped before the nut comes off. The nuts and the like can be prevented from dropping, and the nuts and the like can be prevented from being lost, so that workability and safety can be improved.

In FIG. 7, when the brake is applied, the microcomputer 5 switches the motor 2 by the switching means 6.
Is cut off from the battery 1, the power supply terminals of the motor 2 are short-circuited by the braking means 72 via the brake driving means 71, and the kinetic energy of the motor 2 and the rotary impact mechanism is released as heat to stop the impact tool. ing.

[0020]

According to the present invention, there is provided a rotary striking operation end detecting means for detecting the end of the rotary striking operation based on the output from the rotary striking operation detecting means during the loosening operation. By providing the switching means for stopping the motor by the output of (1), the workability and safety at the time of the loosening operation can be improved.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a control circuit of an impact tool according to the present invention.

FIG. 2 is a longitudinal sectional side view showing an impact tool according to the present invention.

FIG. 3 is a view in the direction of arrow A in FIG. 2 showing a positional relationship between a claw portion of a hammer and a blade portion of an anvil in the impact mechanism of the impact tool according to the present invention.

FIG. 4 is a flowchart showing automatic stop control during loosening work according to the present invention.

FIG. 5 is a state explanatory view showing trajectories of a claw portion and a blade portion during a rotary hitting operation according to the present invention.

FIG. 6 is a waveform chart showing a rotation hitting operation detection signal at the time of the rotation hitting operation according to the present invention.

FIG. 7 is a flowchart showing another automatic stop control at the time of loosening work according to the present invention.

[Explanation of symbols]

1 is a battery, 2 is a motor, 4 is a rotary impact operation detecting means, 5
Is a microcomputer of rotation impact operation end detection means,
6 is a switching means, 21 is a gear mechanism, 22 is an anvil, 23 is a hammer, 31 is a blade, and 32 is a claw.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C038 AA01 AA02 AA03 AA04 BB03 BC04 CA01 CB02 CC03 CC04 CD05 EA03

Claims (5)

[Claims] 1. A motor as a drive source, a gear mechanism for transmitting rotational power of the motor, and a hammer rotatably and axially movable on a rotating shaft that is rotated by an output from the gear mechanism. And an anvil having a wing portion that is rotated by being hit by a plurality of claw portions provided on the hammer, and further includes a rotation hitting operation detecting unit that detects a rotation hitting operation between the claw portion and the wing portion. In the impact tool, a rotation impact operation end detection means for detecting the end of the rotation impact operation based on the output from the rotation impact operation detection means at the time of the loosening operation is provided, and the output from the rotation impact operation end detection means is provided. An impact tool comprising: switching means for stopping a motor. 2. An output from the rotary hitting operation detecting means is a second output generated within a rotary hitting cycle consisting of a first output generated for each rotary hitting operation with the claw portion and the blade portion. 2. The impact tool according to claim 1, wherein the output is eliminated by a dead time shorter than a rotation impact period. 3. The impact tool according to claim 1, wherein the second output is masked by the dead time. 4. When the output from the rotary hitting operation detecting means disappears, and after the dead time elapses, the output is not output even if the output exceeds a predetermined time, it is determined that the rotary hitting operation has ended, and the switching means is determined. The impact tool according to claim 1, wherein the impact tool is controlled. 5. The impact tool according to claim 1, further comprising a braking means for applying a brake to the motor at the end of the rotary impact operation.