JPH07205052A - Power tool device - Google Patents

Abstract

PURPOSE:To conduct the intercepting action of a power source intercepting means surely when an edge portion in the middle of rotary action has come into contact with or approximated a metal object in a structure. CONSTITUTION:The device is equipped with a ground means 55 to connect a main body case 11 to a ground body 37 electrically; a detecting means 33 to detect a ground electric current running through the ground means 55; a power source intercepting means 34 to intercept the power source circuit of a motor 12 in response to the detection of the detecting means 33; and an electric conductor 19 whose one end is fixed at the main body case 11 and whose other end comes into sliding contact with the outer periphery of an edge portion 25. Even in a case in which a space between the outer ring 26 and the inner ring 27 of a bearing body 14 falls into the state of non-conduction, electric connection between the main body case 11 and the edge portion 25 is secured through the electric conductor 19. Accordingly, reliability in regard to the prevention of accidents such as the cutting off of an electric wire in a metal tube, a motor-driven tool edge portion getting chipped, can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power tool device such as a diamond core drill or an electric drill, and more particularly to a power cutoff device suitable for drilling a structure such as a concrete wall of a building.

[0002]

2. Description of the Related Art Conventionally, when a vibration or impact type electric drill such as a diamond core drill is used to make a hole in a concrete wall of a building, the metal pipe buried in the concrete wall is destroyed by breaking the metal pipe. Occasionally, an electric wire inside the metal pipe may be cut, or the metal pipe or the like may be pierced by the blade portion of the electric drill, resulting in damage to the blade portion.

Therefore, as one means for solving such a problem, a detecting means for detecting that a blade of an electric power tool, for example, a vibration type electric drill, comes into contact with a metal object buried in a structure, and this detecting means. There has been proposed a cord reel provided with a power cutoff means for cutting off the power supply circuit of the electric motor in response to the detection of the means.

FIG. 6 is a perspective view showing a cord reel of this type. The cord reel 1 shown in FIG.
And a panel 3 mounted on the side of the cord reel 1. The panel 3 is provided with an outlet 4, an alarm device 5, a function changing switch 6, and the like. A plug 8 and a grounding terminal 9 which are respectively connected to an AC power supply and a grounding body (not shown) are provided at the tip of the power supply cord 7 wound around the cord reel 1. Although not shown in the drawings, the conventional power tool includes a main body case having conductivity, an electric motor built in the main body case and connected to the outlet 4 through a connection cord, and a ground terminal provided on the main body case. And grounding means including. The ground terminal is connected to the ground body via the ground section of the outlet 4 and the ground terminal 9 of the power cord 7.

In the cord reel 1 and the electric power tool device, the plug 8 of the power cord 7 and the ground terminal 9 are provided.
Each of which is connected to an AC power source and a grounding body,
The electric motor is operated with the cord plug of the electric tool (not shown) connected to the outlet 4. When the blade of the power tool comes into contact with a metal object such as a metal pipe (not shown), a ground current flows through the grounding means, so that the power cutoff means 2 cuts off the power supply circuit of the electric motor and the alarm 5 Is set to ring. This stops the operation of the blade part of the power tool,
It is possible to prevent an accident such as cutting the electric wire in the metal tube and an accident that the blade portion of the electric tool is damaged.

[0006]

By the way, in the above-mentioned prior art, the blade portion and the main body case are electrically connected to each other through the bearing body that rotatably supports the rotary shaft of the electric power tool. Therefore, in some cases, the electrical connection between the blade portion and the main body case may not be obtained depending on the internal state of the bearing body. In this way, when the electrical connection between the blade and the body case is insufficient and the blade is in a non-conducting state, the grounding current will flow through the grounding means even if the blade of the power tool contacts the metal object. Since the current does not flow, the power supply circuit of the electric motor cannot be cut off, and therefore, there is a problem that reliability regarding the cutoff operation of the power supply cutoff means is lacking.

The present invention has been made in view of the above-mentioned circumstances in the prior art, and an object of the present invention is to provide a means for cutting off the power supply when the blade part in the rotating operation comes into contact with or approaches a metal object in the structure. An object of the present invention is to provide an electric tool device capable of reliably performing a breaking operation.

[0008]

In order to achieve the above object, the invention according to claim 1 of the present invention is a main body case which is conductive and forms an outer shell, and an electric motor incorporated in the main body case. A rotating body that is electrically driven and includes a blade portion that is abutted against a structure and is driven to rotate by the electric motor; a bearing body that is provided in the main body case and rotatably supports the rotary shaft; and the main body case. And a grounding body, a grounding means for electrically connecting the grounding body, a detecting means for detecting a grounding current flowing through the grounding means, and a power cutoff means for cutting off the power supply circuit of the electric motor in response to the detection by the detecting means. A power tool device configured to stop the electric motor when the blade portion engages with a metal object embedded in the structure, in which the main body case and the rotating body are electrically connected. Structure with It is to.

Further, according to a second aspect of the present invention, the conducting means is provided between the main body case and the blade portion.

Further, in the invention according to claim 3 of the present invention, the conducting means is provided with a conductor having one end fixed to the surface of the main body case and the other end slidably contacting the outer periphery of the blade portion. .

Further, in the invention according to claim 4 of the present invention, the conducting means is constituted by a lubricant having conductivity and contained in the bearing body.

The invention according to claim 5 of the present invention is
The power cut-off means comprises a relay that is energized when the ground current flows and a normally-closed contact that is provided in the power circuit of the electric motor and that is opened by the energization of the relay.

[0013]

In the invention described in claim 1 of the present invention, since the conducting means for electrically connecting the main body case of the electric power tool device and the rotating body is provided as described above, for example, when punching a structure, When the blade of the power tool device touches or approaches a metal object that is embedded in this structure and connected to the grounding body,
Since the electrical connection between the blade portion and the main body case is sufficiently established via the above-mentioned conducting means, the circuit of grounding body-metal object-blade portion-conducting means-main body case-grounding means-grounding body. Is closed and a ground current flows, the detection means detects and the power cutoff means cuts off the power supply circuit of the electric motor. As a result, when the blade during the rotating operation comes into contact with or comes close to the metal object in the structure, it is possible to surely perform the interruption operation of the power interruption means.

Further, according to the second and third aspects of the present invention, since the blade portion and the body case are directly connected as described above, the blade portion and the body case are electrically connected. Is sufficient, whereby the shutoff operation of the power shutoff means is more reliable.

Further, in the invention according to claim 4 of the present invention, since the conducting means is conductive and is made of the lubricant contained in the bearing body as described above, the blade portion is provided on the metal object in the structure. When they come into contact with or come close to each other, the electrical connection between the blade portion and the main body case is sufficiently performed through the lubricant, so that the grounding body-metal object-blade portion-lubricant-main body case-
The circuit of the grounding means-grounding body is closed, and accordingly, the ground current flows, the detection means detects and the power supply cutoff means cuts off the power supply circuit of the electric motor. As a result, when the blade during the rotating operation comes into contact with or comes close to the metal object in the structure, it is possible to surely perform the interruption operation of the power interruption means.

Further, in the invention according to claim 6 of the present invention, since the power interruption means is provided with the relay and the normally-closed contact as described above, the blade portion comes into contact with or approaches the metal object in the structure. When a ground current flows, the normally-closed contact opens due to the biasing of the relay, whereby the power supply circuit of the electric motor can be reliably shut off.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric power tool device of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the power tool device of the present invention as set forth in claims 1, 2, 3, 3, and 5, FIG. 2 is an explanatory view of the power tool device of this embodiment, and FIG. 3 is a book. FIG. 4 is a diagram showing a main part of a power cutoff device according to an embodiment, FIG. 4 is an electric circuit diagram of the electric power tool device of the present embodiment, and FIG. 5 is an electric circuit diagram of detection means provided in the electric power tool device of the present embodiment. The same parts as those shown in FIG. 6 described above in FIGS. 2, 2 and 4 are designated by the same reference numerals. That is,
3 is a panel, 5 is an alarm device, 7 is a power cord, and 8 is a plug.

The power tool device of this embodiment shown in FIG. 1 mainly comprises a cord reel 1a and a power tool 10 such as a diamond core drill.

This electric power tool 10 has a main body case 11 having conductivity and forming an outer shell, an electric motor 12 built in the main body case 11, a rotating body 13 rotationally driven by the electric motor 12, and a main body. The bearing body 14 provided in the opening 11a of the case 11, the operation switch 15 connected to the electric motor 12, the connection cord 17 connected to the operation switch 15 and having the connection plug 16 at the tip, and the connection cord 17 The grounding wire 18 is embedded and has one end connected to the body case 11, and a conducting means, such as a conductor 19, for electrically connecting the body case 11 and the rotating body 13.

As shown in FIG. 2, the main body case 11 has an operation handle 21 formed at the rear end, to which the operation switch 15 is attached, and another operation handle 22 protruding laterally. . As shown in FIG. 3, the rotating body 13 is rotatably supported by a bearing body 14, and a rotating shaft 23 that rotates integrally with the electric motor 12, and the rotating shaft 23.
The drill chuck 24 is provided at the tip of the drill chuck 24 and a blade 25 such as a diamond bit held by the drill chuck 24.

As shown in FIG. 3, the bearing body 14 has an outer ring 26 fitted into the opening 11a of the main body case 11.
An inner ring 27 into which the rotary shaft 23 is fitted, a plurality of balls 28 provided between the outer ring 26 and the inner ring 27,
The outer ring 26 and the inner ring 27 are filled with a lubricant 29. The rotary shaft 23, the drill chuck 24, the blade 25, the outer ring 26, the inner ring 27, and the balls 28.
Have conductivity.

The conductor 19 is formed of, for example, a phosphor bronze plate or a carbon brush material, and has a fixed portion 19a fixed to the main body case 11 with a screw 30 and a sliding contact portion that slidably contacts the outer periphery of the blade portion 25. 19b and.

As shown in FIG. 4, the above-described cord reel 1a includes an outlet 31 to which the connection plug 16 of the electric tool 10 is detachably connected, and other electric equipment (not shown) such as an illumination lamp and a vacuum pump. Other outlet 32 to which the plug for connection of is removably connected, and the ground wire 18
Detection means 33 for detecting a ground current flowing through the power supply circuit, power supply cutoff means 34 for cutting off the power supply circuit of the electric motor 12 in response to detection by the detection means 33, and cutoff release means for canceling the cutoff state of the power supply circuit. And 35.

The outlets 31 and 32 are mounted on the panel 3 of the cord reel 1a and have ground terminals 31a and 32a connected to the grounding body 37, respectively. One of the outlets 31 is connected to an AC power supply 36 via a power cutoff means 34
And the other outlet 32 is directly connected to the AC power supply 36.

The detecting means 33 comprises a detecting portion 33a and a holding portion 33b. In the former detecting portion 33a, the primary winding side is connected to the AC power source 36 via the wirings a and b, and the secondary winding side is connected. A transformer 41, one end of which is connected to the grounding body 37 via a wiring c _1, and one end of which is connected to the secondary winding side of the transformer 41 via a wiring c ₂ and the other end of which is a resistor 42, wiring. a photodiode 43 connected to the ground terminal 31a of the outlet 31 via d, and the photodiode 43
And a diode 44 that is connected in parallel with the device and allows a current to flow in the opposite direction. On the other hand, in the latter holding portion 33b, one of the input sides is connected to the AC power supply 36 via the wiring b, and the other is connected to the AC power supply via the wirings a and f, the power interruption means 34, the interruption cancellation means 35 and the wiring e. It comprises a diode bridge 46 connected to 36, a photothyristor 47 supplied with current from the diode bridge 46, resistors 48, 49 and a capacitor 50 for maintaining the power supply of the photothyristor 47.

The power cutoff means 34 is the detection means 33.
Normally-closed contact 51b provided between the power source circuit of the electric motor 12, that is, the AC power supply 36 and the outlet 31 and opened by the activation of the relay 51.
The normally open contact 51a, which is closed by the bias of the relay 51, is connected to the alarm device 5.

The cutoff releasing means 35 is provided separately from the cord reel 1a, for example, a reset button 52 mounted on the operator himself and a reset button 52 having a length of about 5 m.
Connecting cord 53 for remote operation, which is extended between the power cord 36 and the cord reel 1a, a reset relay 54 which is interposed between the reset button 52 and the AC power supply 36, and a diode bridge 46 and the relay 51, It is composed of a normally closed contact 54b which opens when the reset relay 54 is energized. The ground wire 18, the ground terminal 31a, the wiring d, the wiring c ₂ , and the wiring c ₁ constitute a grounding means 55 for electrically connecting the main body case 11 and the grounding body 37.

In this embodiment, when the worker uses the power tool 10, the connection plug 8 of the power cord 7 of the cord reel 1a is connected to the AC power supply 36, and the cord reel 1a is connected.
When the plug 16 of the connection cord 17 is connected to the outlet 31 of a, the reset button 52 is attached to the operator himself, and the operation switch 15 of the electric tool 10 is pressed, the AC power supply 36, the power supply cord 7, and the cord reel 1a. , Electricity is supplied to the electric motor 12 via the connection cord 17, so that the electric motor 12 is activated and the rotating body 1 including the blade portion 25.
3 is rotationally driven. Therefore, the operator presses the blade portion 25 against the structure, for example, the concrete wall 61 shown in FIG. 2 to make a hole.

After that, when the blade 25 comes into contact with the metal object 62 buried in the concrete wall 61, the grounding body 37-wiring c _1- wiring c ₂ on the secondary winding side of the transformer 41-photodiode 43-resistor 42-wiring d-ground terminal 3
The circuit of 1a-grounding wire 18-main body case 11-conductor 19-blade portion 25-metal object 62-grounding body 37 is closed, and a ground current flows through this circuit.
3 emits light, and the photothyristor 47 turns on.
As a result, the AC power supply 36-wiring b-diode bridge 46-photothyristor 47-resistor 49-diode bridge 46-wiring e-normally closed contact 54b-relay 51-
The circuit of wiring f-wiring a-AC power supply 36 is closed, relay 51 is energized, and photothyristor 47 continues to be turned on by the action of resistors 48, 49 and capacitor 50. At this time, due to the urging of the relay 51, the normally closed contact 51b is opened to stop the electric motor 12 and the rotating body 13, and the normally open contact 51a is closed to sound the alarm device 5.

Next, when the operator stops pressing the operation switch 15 of the power tool 10 and operates the reset button 52, the circuit of AC power supply 36-reset relay 54-reset button 52-AC power supply 36 is closed. The reset relay 54 is energized to open the normally closed contact 54b. With this,
The current flowing through the photothyristor 47 is cut off for a moment, the photothyristor 47 is turned off, and the relay 51 is deenergized. As a result, the normally open contact 51a opens and the alarm device 5
Stops, the normally closed contact 51b closes, and the outlet 3
The disconnection state of the power supply circuit to 1 is released, and electricity is supplied again to the electric motor 12 of the electric power tool 10. Therefore, when the operator checks the metal object 62 with which the blade portion 25 is in contact and determines whether to restart or stop the drilling work, when restarting the drilling work, the operator operates the operation switch 15 of the power tool 10. When operated again, the electric motor 12 is started.

In the embodiment thus constructed, the conductor 19 which electrically connects the main body case 11 and the rotating body 13 is provided, so that the outer ring 26 and the inner ring 27 of the bearing body 14 are not electrically connected. Even in the case where the blade portion 25 comes into contact with the metal object 62 in the structure 61, the power source cutoff means 3
It is possible to reliably perform the shutoff operation of No. 4. Further, since the blade portion 25 itself and the main body case 11 are directly connected to each other, that is, the electrical connection between the blade portion 25 and the main body case 11 is sufficient, the shutoff operation of the power shutoff means 34 is more reliable. Is.

Further, the outlet 32 of the cord reel 1a
Is directly connected to the AC power supply 36 without passing through the power cutoff means 34 and is always energized.
By connecting an illuminating lamp, a vacuum pump, etc. to the above, electricity can be supplied to the illuminating lamp, the vacuum pump, etc. via the cord reel 1a, regardless of the operating state of the electric tool 10.

In this embodiment, the photothyristor 47 is provided as a holding means for holding the exciting operation of the relay 51. However, instead of the photothyristor 47,
The self-holding contact of the relay 51 may be provided, and the exciting operation of the relay 51 may be held by the self-holding contact, or a microcomputer may be provided and the exciting operation of the relay 51 may be held by the control of the microcomputer. You may do it.

Further, in this embodiment, the conductor 19 is fixed to the main body case 11 and the sliding contact portion 19b is slidably contacted with the outer periphery of the blade portion 25. Instead of being slidably contacted with the outer periphery of the blade portion 25, The other part of the rotating body 13, that is, the rotating shaft 2
It may be slidably in contact with the outer periphery of the drill chuck 24 or the outer periphery of the drill chuck 24. If necessary, a spring member that biases the sliding contact portion 19b of the conductor 19 toward the rotating body 13 may be provided to increase the pressure with which the sliding contact portion 19b slides in contact with the rotating body 13. .

Further, in this embodiment, the relay 51 of the power cutoff means 34 is energized when the blade portion 25 comes into contact with the metal object 62, but the present invention is not limited to this, and the blade portion may be attached to the metal object 62. When 25 approaches, the relay 51 can be energized by utilizing high frequency induction or change of electrostatic capacity. This can prevent damage to the metal object 62.

Further, in this embodiment, the conductor 19 is provided as a conducting means for electrically connecting the body case 11 and the rotating body 13, but instead of the conductor 19, the bearing body 1 is provided.
By enclosing a conductive lubricant in 4, the main body case 11 and the rotating body 13 can be electrically connected via this lubricant. In this case, since it is not necessary to provide the conductor 19 between the main body case 11 and the blade portion 25, the structure of the electric power tool 10 does not have to be complicated.

[0037]

Since the present invention is configured as described above, when the blade portion during the rotating operation comes into contact with or comes close to the metal object in the structure, it is possible to surely perform the shutting-off operation of the power shut-off means. Therefore, there is an effect that it is possible to improve reliability with respect to prevention of an accident of cutting an electric wire in a metal pipe and prevention of an accident of breaking a blade portion of an electric tool.

[Brief description of drawings]

FIG. 1 is a diagram showing a power tool device according to the present invention.
3 is a block diagram showing an embodiment described in FIG.

FIG. 2 is an explanatory diagram of the power tool device according to the present embodiment.

FIG. 3 is a diagram showing a main part of a power cutoff device according to the present embodiment.

FIG. 4 is an electric circuit diagram of the power tool device according to the present embodiment.

FIG. 5 is an electric circuit diagram of a detection unit included in the electric power tool device according to the present embodiment.

FIG. 6 is a perspective view showing a conventional cord reel.

[Explanation of symbols]

 1a Code reel 10 Power tool 11 Main body case 12 Electric motor 13 Rotating body 14 Bearing body 19 Conductor (conducting means) 19a Fixed part 19b Sliding contact part 25 Blade part 33 Detecting means 34 Power cutoff means 37 Grounding body 51 Relay 51b Normally closed contact 55 Grounding means 61 Structure 62 Metal object

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshiji Tamaru 1-6-6 Kandanishikicho, Chiyoda-ku, Tokyo Inside Hitachi Building System Service Co., Ltd.

Claims (5)

[Claims] 1. A main body case that is electrically conductive and forms an outer shell, an electric motor that is built into the main body case, and a blade portion that is electrically conductive and abuts against a structure, and is rotationally driven by the electric motor. A rotating body, a bearing body provided in the main body case for rotatably supporting the rotating body, a grounding means electrically connecting the main body case and a grounding body, and a ground current flowing through the grounding means. And a power cutoff unit that cuts off the power supply circuit of the electric motor in response to the detection by the detection unit, and the electric motor when the blade portion engages with a metal object embedded in the structure. In the electric power tool device, the electric power tool device is provided with a conduction means for electrically connecting the main body case and the rotating body. 2. The electric tool device according to claim 1, wherein the conducting means is provided between the main body case and the blade portion. 3. The electric tool device according to claim 2, wherein the conducting means includes a conductor having one end fixed to the surface of the main body case and the other end slidingly contacting the outer periphery of the blade portion. 4. The electric tool device according to claim 1, wherein the conducting means is made of a lubricant having conductivity and contained in the bearing body. 5. The power cut-off means comprises a relay that is energized when a ground current flows, and a normally-closed contact that is provided in the power circuit of the electric motor and that is opened by the energization of the relay. The power tool device according to any one of 4 above.