JPH08174441A - Power screw driver - Google Patents

Abstract

PURPOSE: To save a clutch mechanism, to hold the sufficient output torque, and to simplify and facilitate the smooth and quick fitting of a screw to a material to be fitted by screw, especially a delicate and weak material, by specifying the final fastening position of a screw in relation to a material to be fitted by a screw, and appropriately detecting this fastening position so as to stop the screw fastening work. CONSTITUTION: In an electric driver, which is provided with a grip part 10 with a built-in electric motor and in which a driver bit 14 is connected to an output shaft of this electric motor freely to be disconnected, the periphery of the driver bit 14 is provided with a mouth piece 24, which surround a screw S in the condition that the mouth piece 24 holds a screw S in the tip of the driver bit and which is elastically moved in the axial direction. A means for operating a switch 30, which stops the drive of the electric motor with the movement for displacement of the mouth piece 24 due to the abutment of the mouth piece 24 on the material 36 to be fitted by screw, is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric screwdriver including a rechargeable screwdriver, and in particular, when tightening a screw or the like, the screw is always completed at a proper position with respect to a screw mounting object. The present invention relates to improvement of an electric screwdriver equipped with a mouthpiece.

[0002]

2. Description of the Related Art Conventional electric screwdrivers generally perform proper tightening of screws. Therefore, at the stage of tightening a screw to a desired screw mounting object, a predetermined load torque is applied between the output shaft of the electric motor and the driver bit. When a clutch mechanism is provided to detect this and to cut off the transmission of the rotational output of the output shaft, a mechanism for automatically stopping the electric motor simultaneously with the clutch mechanism is provided. Various proposals have been made and implemented (for example, Japanese Examined Patent Publication No. 60-13798).

[0003]

However, in the conventional electric screwdriver, when a screw is attached to a material having a variation in hardness such as a wood screw, an electric driver having a sufficient output torque is used. It is necessary to use a screwdriver to tighten the screws. And in this case,
If the screw to be used is a countersunk screw, it is a proper mounting state that its head surface is flush with the surface of the screw mounting object. Therefore, in this case, if an electric screwdriver with a conventional clutch mechanism is used, screw tightening will be completed at the time when a predetermined load torque is detected regardless of the proper mounting state of the screw, so the set torque will be small. If the screw is excessive, the screw cannot be properly mounted. If the set torque is too large, the screw will penetrate deeper than the proper screw to damage the screw mounting object.

For this reason, in the past, when installing such a wood screw, the worker always changes the set torque or sets the set torque to a large value during the installation work, and the tightened state of the screw is always visually recognized. However, it has to be adjusted manually. In this case, there is a risk of damaging the object to which the screw is attached when the screw is over-tightened, and there is a problem that a large amount of skill is required for the work to properly attach the screw.

In addition, when a screw is attached to a plurality of screw attachment objects having different hardness, if the surface member is soft, the electric screwdriver having the clutch mechanism adapts the set torque to the hard member. Adjustment, the screws will be overtightened against the soft member,
It is difficult to make a proper mounting state.

Further, when attaching a small screw or the like to a screw mounting object similar to the above, an electric screwdriver provided with a clutch mechanism capable of freely adjusting the setting of the output torque is used to output the output torque. By setting and performing the screw tightening work, it is possible to complete the screw tightening in the proper mounting state of the screw as described above.
However, in this case, when the screw is obliquely attached to the screw hole, a predetermined load torque is detected without the screw being properly attached, and the screw tightening is completed at that time. There are difficulties.

Therefore, an object of the present invention is to define a final tightening position of a screw with respect to a screw mounting object,
By performing this position detection properly and stopping the screw tightening operation, the clutch mechanism of the conventional complicated structure can be omitted, and a particularly fragile screw mounting object can be held while maintaining sufficient output torque. An object of the present invention is to provide an electric screwdriver capable of easily and easily achieving smooth and quick screw attachment to a screwdriver.

[0008]

An electric screwdriver according to the present invention is an electric screwdriver in which a grip portion having an electric motor built therein is provided, and a driver bit is detachably connected to an output shaft of the electric motor. Provided on the outer periphery of the bit is a mouthpiece that surrounds the screwdriver at the tip of the driver bit and that moves elastically in the axial direction. It is characterized in that means for activating a switch for stopping the driving of the motor is provided.

In the above electric screwdriver, the mouthpiece has an opening at the tip end for accommodating and holding the screw head at the tip of the driver bit, and the rear end at the tip of the grip portion. The tip end of the attached sleeve cover can be elastically abutted via a coil spring, and the tip end portion of the slide pipe fitted in the sleeve cover can be length-adjustably coupled and fixed.

In this case, the rear end of the mouthpiece and the tip of the slide pipe can be screwed together, and a set screw whose position can be adjusted can be provided at the connecting portion of the mouthpiece.

Further, the slide pipe can be configured so as to engage with a locking step portion provided on the inner peripheral surface of the sleeve cover and project from the tip of the sleeve cover to a predetermined position.

Further, a slide flange, which presses and separates from the operating portion of the switch, is arranged opposite to the rear end portion of the slide pipe connected to the rear end portion of the mouthpiece, and this slide flange is constantly connected to the switch through a coil spring. It can be configured such that it is pressed against the actuating portion and is elastically displaced by coming into contact with the slide pipe to separate from the actuating portion of the switch.

By providing a clutch mechanism along with the electric screwdriver, it is possible to provide a structure having a screw attachment abnormality determining function.

Furthermore, in the electric screwdriver having the clutch mechanism, the clutch mechanism can be released by the sensor function of the mouthpiece.

[0015]

According to the electric screwdriver of the present invention, when the final tightening position is reached for the screw attachment target, the tip of the mouthpiece abuts the screw attachment target and moves upward against the spring elasticity. Moving. Then, when the screw reaches the proper position with respect to the object to which the screw is attached, the rear end of the slide pipe that moves integrally with the mouthpiece comes into contact with the slide flange, and moves the spring upward against the spring elasticity. Move to and move it away from the operating part of the switch. As a result, the switch operation is performed, the driving of the electric screwdriver is stopped, and the screw tightening operation can be completed.

[0016]

Embodiments of the electric screwdriver according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 and FIG. 2 are cross-sectional views of an essential part showing an embodiment of an electric screwdriver according to the present invention. However,
1 and 2, reference numeral 10 indicates a grip portion of an electric driver having an electric motor (not shown) built therein.

At the lower end of the grip portion 10, a cylindrical grip portion casing for accommodating a planetary speed reduction mechanism (not shown) which can be coupled to the output shaft of the electric motor to obtain a required deceleration rotation driving force. 12 and a sleeve cover 18 that surrounds a drive shaft 16 that is coupled to this planetary speed reduction mechanism and transmits a rotational drive force to a driver bit 14, which will be described in detail later, are sequentially connected.

A bit chuck mechanism 20 is provided at the tip of the drive shaft 16, and the holding end portion 14a of the driver bit 14 is detachably inserted into the bit chuck mechanism 20.

Further, a locking step portion 18a slightly protruding inward is provided on the inner peripheral surface of the tip end portion of the sleeve cover 18, while an engaging step portion 22a engaging with the locking step portion 18a is provided in a protruding manner. The slide pipe 22 is slidably inserted and locked in the vertical direction. However, the tip of the slide pipe 22 projects from the tip of the sleeve cover 18, and the screw portion 22b is provided on the outer periphery of the sleeve cover 18, so that the driver bit 14
The mouthpiece 24, which is configured to surround the whole of the, is joined. In this case, at the tip of the mouthpiece 24, as shown in FIG.
As shown in FIG. 2, an opening 24a is provided for accommodating and holding the screw head in a state where the screw head is fitted to the tip of the driver bit 14, and a screw groove 24b for screwing with the screw portion 22b is formed on the inner peripheral portion of the rear end. Is engraved and screwed onto the tip of the slide pipe 22. Then, a set screw 26 is appropriately screwed to the rear end portion of the mouthpiece 24, and the tip of the set screw 26 is fitted and locked to the screw portion 22b provided on the outer peripheral portion of the end of the slide pipe 22. Thereby, the mouthpiece 24 can be fixed so that the position of the mouthpiece 24 can be adjusted in the axial direction of the driver bit 14. Further, between the front end of the sleeve cover 18 and the rear end of the mouthpiece 24,
A coil spring 2 is formed along the outer peripheral surface of the slide pipe 22.
8, the mouthpiece 24 is always elastically biased toward the tip of the driver bit 14 (see FIG. 1).

Further, inside the sleeve cover 18, a micro switch 30 is provided on the other end side of the slide pipe 22, and the micro switch 30 is provided.
A slide flange 32 for operating the switch, which is pressed against and separated from the switch operating portion 30a, is inserted so as to surround the drive shaft 16. In this case, the slide flange 3
The distal end of the second pipe 2 is arranged so as to face the rear end of the slide pipe 22 and is locked to a locking part 16 a provided on a part of the outer circumference of the drive shaft 16. Then, at the other end of the slide flange 32, the coil spring 34 is interposed between the slide flange 32 and the casing 12, and the slide pipe 2
It is elastically urged in the direction of 2, so that the flange portion 32a of the slide flange 32 is always kept in the micro switch 3
The switch actuating part 30a of 0 is pressed and held (see FIG. 1).

Next, the operation of the electric screwdriver having the above construction will be described.

First, referring to FIG. 1, a driver bit 1
4 shows a case in which a wood screw S is held at the tip of 4 and the wood screw S is attached to a screw attachment object 36 such as wood. In this case, the mouthpiece 24 and the slide pipe 22 are
The engagement step 22a of the slide pipe 22 is positioned on the lower side by the elastic action of the coil spring 28, and is engaged with the engagement step 18a of the sleeve cover 18. Further, the slide flange 32, which is arranged to face the rear end of the slide pipe 22, is slightly separated from the slide pipe 22 and is located below by the elastic action of the coil spring 34.
In 2a, the switch operating portion 3 of the microswitch 30
Hold 0a under pressure. Therefore, in this state, if the main switch of the electric screwdriver is operated, the built-in electric motor can be immediately driven to rotationally drive the driver bit 14 to perform the screw tightening operation.

In this way, the driver bit 14 is rotationally driven to perform the screw tightening operation, and the screw mounting target 3
When the final tightening stage for 6 is reached, the tip opening 24 a of the mouthpiece 24 abuts on the screw attachment object 36 and moves upward against the elasticity of the coil spring 28. Then, as shown in FIG. 2, when the screw S reaches an appropriate position with respect to the screw attachment object 36, the rear end of the slide pipe 22 that moves integrally with the mouthpiece 24 becomes the slide flange 32. It abuts and moves it upwards against the elasticity of the coil spring 34,
2a is separated from the switch actuating portion 30a of the micro switch 30 (see FIG. 2). As a result, the micro switch 30 operates as a switch to momentarily stop the driving of the electric screwdriver, and the screw tightening operation is completed.

As means for momentarily stopping the driving of the electric driver, for example, a dynamic braking circuit is adopted for the electric motor, and the dynamic braking circuit is activated when the micro switch 30 is switched. As a result, it is possible to easily achieve the instantaneous stop of the electric driver.

In particular, according to the electric screwdriver of the present invention, as shown in FIG. 3, the surface of the substrate 36a made of a relatively hard material such as wood is made of a relatively soft material such as a gypsum board or a heat insulating material. When the screw S is attached to the screw attachment target 36 provided with the coating layer 36b, even if the torque for driving the driver bit 14 is set to be relatively large, the screw S is attached to the coating layer 36b as shown in the figure. When the proper position is reached, position detection is performed via the mouthpiece 24, and the screw tightening operation can be immediately completed. Therefore, without damaging the coating layer 36b,
Proper mounting of the screw S can be easily achieved.
Such an operation cannot be realized at all with an electric driver having a conventional clutch mechanism.

On the other hand, the electric screwdriver according to the present invention is the same as the electric screwdriver provided with the conventional clutch mechanism, provided with the above-described screw proper position detection mechanism according to the present invention, and the screw proper position detection mechanism operates. By setting so that the operation of the clutch mechanism is disabled until, the operation of the clutch mechanism is confirmed before the proper position detection mechanism of the screw operates, for example, it indicates an abnormal mounting state of the screw. Therefore, in this case, the function of discriminating the screw attachment can be exerted.

Further, as described above, in the electric screwdriver having the conventional clutch mechanism, the mouthpiece 2
The sensor function of 4 can also be configured to release the clutch mechanism when it operates.

As an electric driver having the clutch mechanism, for example, a driver bit is coupled to an output shaft of an electric motor through a planetary speed reduction mechanism, and an internal gear that meshes with a planetary gear of the planetary speed reduction mechanism is gripped. The inner gear and one end of the grip casing are closed to face each other, and a through hole is formed in the facing surface of the grip casing. A steel ball is housed, the steel ball is elastically held from the outside of the grip casing by a sleeve with a flange, and the steel ball is fitted into and abutted in a groove provided on the facing surface of the internal gear to automatically A clutch device is known.

The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various design changes can be made without departing from the spirit of the present invention. Is.

[0031]

As is apparent from the above-described embodiments, the electric screwdriver according to the present invention is provided with the grip portion having the electric motor built therein, and the driver bit is detachably coupled to the output shaft of the electric motor. In an electric screwdriver,
A mouthpiece is provided on the outer periphery of the driver bit, which surrounds the tip of the driver bit while surrounding the screw, and which is elastically movable in the axial direction. By providing the means for activating the switch for stopping the drive of the electric motor, the screw tightening operation can be surely and instantaneously stopped at an appropriate position of the screw with respect to the screw mounting object. It is possible to easily and smoothly attach a screw to a fragile screw attachment target while maintaining a sufficient output torque without providing a conventional clutch mechanism having a complicated structure.

In particular, the electric screwdriver according to the present invention is an electric screwdriver for mounting wood screws, and is simpler in holding the screw and operating to an appropriate tightening position as compared with an electric screwdriver having a conventional clutch mechanism. In addition to being surely achieved, it has an advantage that it can be manufactured at low cost by a simple structure.

In this case, in the electric screwdriver of the present invention,
As described above, the driving of the screw can be stopped instantaneously by detecting the position of the screw with respect to the screw mounting target. Therefore, for example, the adjustment position of the mouthpiece can be adjusted with respect to the screw mounting target. If the screw is temporarily set to the temporary fixing position, the proper temporary screw fixing work can be quickly and reliably achieved.

According to the electric screwdriver of the present invention,
It is possible to easily and safely mount the screw in an appropriate state on a complicated place or a narrow recessed place where the operator cannot visually recognize it.

Further, in the electric screwdriver for mounting the machine screw, the mouthpiece formed by the electric screwdriver of the present invention is additionally provided to the electric screwdriver having the conventional clutch mechanism, so that a predetermined load torque can be detected in the screw tightening work. By the position detection of the present invention and the position detection of the present invention, it is possible to easily achieve the screw tightening work that can always confirm that the screw is properly attached.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of an electric screwdriver according to the present invention.

FIG. 2 is a cross-sectional view of essential parts showing an operating state of the electric screwdriver shown in FIG.

FIG. 3 is a cross-sectional view of essential parts showing another embodiment of a state where a screw is attached by an electric screwdriver according to the present invention.

[Explanation of symbols]

 10 gripping part 12 gripping part casing 14 driver bit 14a holding end part 16 drive shaft 16a locking part 18 sleeve cover 18a locking step part 20 bit chuck mechanism 22 slide pipe 22a engaging step part 22b screw part 24 mouthpiece 24a opening part 24b Screw groove 26 Set screw 28 Coil spring 30 Micro switch 30a Switch operating part 32 Slide flange 32a Flange part 34 Coil spring 36 Screw installation target 36a Substrate 36b Coating layer S screw

Claims (7)

[Claims] 1. An electric screwdriver having a grip portion having an electric motor built-in, and a driver bit being detachably coupled to an output shaft of the electric motor, wherein a screw is provided at a tip of the driver bit on an outer periphery of the driver bit. A means for activating a switch that stops the drive of the electric motor by providing a mouthpiece that surrounds the held state and elastically moves in the axial direction, and moves and displaces by contacting the mouthpiece with a screw attachment target An electric screwdriver equipped with a mouthpiece that is provided. 2. A sleeve cover in which a mouthpiece has an opening at a tip end thereof for accommodating and holding a screw head at a tip end of a driver bit, and a rear end portion thereof is attached to a tip end of a grip portion. 2. The electric screwdriver according to claim 1, wherein the tip of the slide screw is elastically abutted via a coil spring and is fixedly coupled to the tip end of a slide pipe fitted in the sleeve cover in a length adjustable manner. 3. The electric screwdriver according to claim 2, wherein a rear end portion of the mouthpiece and a tip portion of the slide pipe are screwed together, and a position adjusting set screw is provided at the joint portion of the mouthpiece. 4. The slide pipe is configured to engage with a locking step portion provided on an inner peripheral surface of the sleeve cover and project from a tip of the sleeve cover to a predetermined position.
The listed electric screwdriver. 5. A slide flange, which presses and separates from the operating portion of the switch, is arranged opposite to the rear end portion of a slide pipe connected to the rear end portion of the mouthpiece, and this slide flange is always connected to the switch through a coil spring. 3. The electric screwdriver according to claim 2, wherein the electric driver is configured to be pressed against the actuating portion and elastically displaced by coming into contact with the slide pipe to separate from the actuating portion of the switch. 6. An electric screwdriver provided with a clutch mechanism in addition to the electric screwdriver according to claim 1, having a screw attachment abnormality determination function. 7. The electric screwdriver according to claim 1, further comprising a clutch mechanism, wherein the clutch mechanism is released by a sensor function of a mouthpiece.