JPS6347072A - Clutch type clamping tool - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a clutch type tightening tool, and more particularly to a clutch disengagement detection device for this type of tool.

[Background of the invention]

Before explaining the present invention, a conventional clutch-type tightening tool will be explained. In this type of conventional tool, a switch for generating a motor stop signal is turned on in conjunction with disengagement of the clutch to stop the motor. It uses a mechanism,
After the clutch is disengaged, the clutch is pressed and engaged again by the pressing force of the tightening force adjustment spring, and at the same time, the above-mentioned switch for generating the motor stop signal is shut off by this pressing force.

However, due to force, in the prior art described above, the operation of turning on or cutting off the switch for generating a motor stop signal is affected by the clutch disengagement speed, the pressing force of the tightening force adjustment spring, etc. This has caused problems such as chattering of the switch, damage to the contacts due to high-speed movement of the movable piece inside the switch, and even damage to the movable piece itself. In particular, if the operation of turning on or off the switch is affected by the pressing force of the tightening force adjustment spring, the greater the tightening force required for the spring, the lower the reliability of the switch for generating the motor stop signal. There was a problem. Also, if the switch is turned on when the motor is rotating slowly, that is, when the clutch disengages slowly, the motor will stop, but
At this time, the clutch is held in the disengaged state.

Therefore, when the electric motor is restarted in this state, it immediately stops and the electric motor does not rotate.

[Purpose of the invention]

The present invention was made as a result of studies to solve the problems of the prior art described above, and its purpose is to provide an improved tool that is superior to the conventional tool in terms of both operability and service life. The present invention aims to provide a clutch-type tightening tool that has the following advantages.

[Summary of the invention]

In order to achieve the above object, the present invention has a dog clutch that is pressed and engaged by a clamping force adjustment spring that can freely adjust the pressing force, and a load larger than the pressing force of the clamping force adjustment spring is applied to the tool. In the clutch-type tightening tool that is structured to disengage the dog clutch when the dog clutch is disengaged, an electromagnetic sensor detects the dog clutch disengagement operation, and the output signal of the electromagnetic sensor is used to control power supply to the electric motor. It is characterized by comprising means for blocking.

That is, the present invention focuses on the fact that when a piece of iron moves closer and closer to the tip of an electromagnetic sensor composed of a permanent magnet and a coil, a change in magnetic flux is caused and an alternating current voltage is induced in the coil. The mechanism is devised so that the motion is detected by an electromagnetic sensor and the motor is stopped by the output signal of the electromagnetic sensor.

[Embodiments of the invention]

Hereinafter, the present invention will be explained based on one embodiment of the drawings. FIG. 1 is a longitudinal cross-sectional view of a clutch-type tightening tool according to the present invention, FIG. 2 is a cross-sectional view taken along the line II in FIG. 1, FIG. 3 is a partially enlarged view of FIG. 1 showing a state in which the clutch is disengaged, and FIG. 4 is an electric circuit diagram.

In FIGS. 1 to 3, 1 is an electric motor, and 2 is a speed reduction device using a planetary gear mechanism. A fixed clutch 3 supports the planetary gear 2a of the speed reduction device 2. A plurality of rods 4 are protruded from the fixed clutch 3 to form a cam. 5 is a shaft, 74. A socket 7 holding a driver bit 6 is connected and supported by a pin 8 and a set screw 9, and a movable clutch 10 consisting of a rotating plate 1 and a steel ball 12 is connected to the key 1 at the other end.
3 so that they rotate together.

The steel balls 12 are housed so as to be freely protrusive and retractable from both end faces of the rotary plate 11, and due to the pressing force of the tightening force adjustment spring 14,
It is pressed and engaged with the fixed clutch 3 via a sleeve 15 and a push pin 16.

18 is a gear cover. 20 is an electromagnetic sensor as a motor stop signal generator, and a holder 19 is mounted on the gear cover 18.
The electromagnetic sensor 20 is held by the coil 2.
1, a magnet 22, and an iron core 23.

In FIG. 4, 24 indicates a DC power supply. Reference numeral 25 is a starting switch for starting the electric motor 1, and reference numeral 26 is a forward/reverse changeover switch for selecting whether to rotate the electric motor in the normal or reverse direction, that is, whether to tighten or loosen the motor. 28 is an NPN) transistor, start switch 25
When the power is turned on, the base is energized by the resistor 27, so it becomes conductive and rotates the motor. 30 is a thyristor, and when the clutch disengagement operation is performed and the electromagnetic sensor 20 outputs a signal, the amplifier 29 and the resistor 31
The gate is energized to conduct through the NPN) run raster 320 base to the resistor 33.

At the same time, the gate of the thyristor 35 is energized via the resistor 37. NPN) transistor 3
When NPN transistor 28 becomes conductive, the base and emitter of the NPN transistor 28 are short-circuited, resulting in a cutoff state, and the power supply to the motor 1 is cut off. On the other hand, since the thyristor 35 becomes conductive and short-circuits the motor 1 via the resistor 36, dynamic braking is applied to the motor 1 to immediately stop its rotation.

Now, the overall operation of the clutch-type tightening tool according to the present invention will be described below.

Turn on the start switch 25, rotate the electric motor 1, and
The rotational force is transmitted to the fixed clutch 3 and the movable clutch 10 via the reduction gear 2, and further transmitted to the driver bit 6 via the key 13, shaft 5, and socket 7.
For example, a screw or the like (hereinafter referred to as a screw for convenience) is tightened. As the screw tightening progresses and reaches a predetermined tightening force, the steel ball 12 overcomes the pressing force of the tightening force adjustment spring 14 and is pushed toward the axial sleeve 17, causing the fixed clutch 3 and movable clutch 10 to engage. When the engine is in a detached state, the transmission of rotational force is cut off. On the other hand, the steel ball 12 has a sleeve 17,
The sleeve 15 is pushed out in the axial direction via the push pin 16. At this time, the sleeve F approaches the tip of the electromagnetic sensor 20 and generates a positive voltage in the coil 2. As a result, the rotation of the electric motor 1 is stopped and the screw tightening is completed. Moreover, when the steel ball 12 overcomes the cam surface formed by the rollers 4 of the fixed clutch 3, it is again pressed against the fixed clutch 3 via the sleeves 15 and 17 and the push pin 16 by the pressing force of the tightening force adjustment spring 4. It will be done. At this time, a negative voltage is generated in the output of the electromagnetic sensor 20, and the process waits until the next tightening operation.

Next, the clutch riding state will be explained.

As shown in FIG. 3, the clutch riding state refers to a state in which the fixed clutch 3 and the movable clutch 0 are in a disengaged state, and the rollers 4 and the steel balls 12 overlap on the shaft. This state occurs when the rotation of the electric motor is slow, the clutch is disengaged, and the compartment motor is stopped. Even if the next tightening work is performed in this state, the output of the electromagnetic sensor 20 is a negative voltage, so the output is sent to the amplifier 31 in FIG.
starts, and the clutch returns from its disengaged state to its initial engaged state.

〔Effect of the invention〕

The present invention is as described above, and as is clear from the explanation of the illustrated embodiments, according to the present invention, clutch disengagement can be detected without contact using an electromagnetic sensor, so that a highly reliable and long-life clutch can be achieved. Furthermore, by using an electromagnetic sensor, it is possible to easily restart the clutch when it runs over, and the operability of this type of tool can be improved.

[Brief explanation of the drawing]

The drawings show an embodiment of the clutch-type tightening tool according to the present invention, and FIG. 1 is a longitudinal sectional view thereof, and FIG.
3 is a partially enlarged view of FIG. 1 showing a state in which the clutch is disengaged, and FIG. 4 is an electric circuit diagram. DESCRIPTION OF SYMBOLS 1... Electric motor, 3... Fixed clutch, 10... Movable clutch, 14... Tightening force adjustment spring, 20...
...Electromagnetic sensor. Name of patent applicant Hitachi Koki Co., Ltd.

Claims (1)

[Claims] 1. It has a dog clutch that presses and engages with a clamping force adjustment spring that can freely adjust the pressing force, and when a load larger than the pressing force of the clamping force adjustment spring is applied to the tool, the dog clutch is activated. A clutch-type tightening tool having a structure for disengaging the dog clutch is provided with a means for detecting the disengagement operation of the dog clutch by an electromagnetic sensor and cutting off power supply to the electric motor based on an output signal of the electromagnetic sensor. A unique clutch type tightening tool.