JPH0775908A - Electric drill with metal detector - Google Patents

Abstract

PURPOSE:To provide an electric drill with a metal detector which allows easy and quick resetting of a cut-off power circuit. CONSTITUTION:A detecting means 24 to detect that the drilling portion 11 of an electric drill 10 is put in contact with a metal material, a power cut-off means 25 to cut off a power circuit in the electric drill 10 in accordance with the detection of the detecting means 24 and a holding means 26 to hold the cut-off operation of the power cut-off means 25 are provided. A resetting contact is provided on an operating switch for the electric drill to reset a cut-off condition.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electric drill with a metal detector.

[0002]

2. Description of the Related Art Generally, when an electric drill is used to make a hole in a concrete wall of a building, the buried pipe buried in the concrete wall or the like is destroyed, and the power inside the buried pipe is cut off, or the concrete wall is damaged. Accidents often occur when the cone of an electric drill is applied to the buried rebar and the cone is broken.

Conventionally, as one means for solving such a problem, a detecting means for detecting that a cone of an electric drill has come into contact with a metal object, an alarm device and a power shutoff which respectively operate in response to the detection by the detecting means. A metal detection device for an electric drill having means is put to practical use. Related to this metal detection device, for example, the product name "Metal sensor reel" manufactured by Hataya Seisakusho (reference catalog number: 1
990.5. TOP. 30,000 49).

FIG. 3 is a perspective view showing a conventional metal detecting device of this type.

A metal detecting device 2 is provided on the cord reel 1 shown in FIG.
And a power cutoff unit (not shown) built in the disk, and a panel 3 mounted on the side of the cord reel 1 and covering the detection unit and the power cutoff unit. The panel 3 is provided with an outlet 4, an alarm device 5, a function changing switch 6, and the like. At the tip of the power cord 7 wound on the cord reel 1,
A plug 8 and a ground terminal 9 which are respectively connected to an AC power supply and a grounding body (not shown) are provided.

In this metal detecting device 2, the plug 8 and the ground terminal 9 of the power cord 7 are connected to an AC power source and a grounding body, respectively, and the outlet 4 is connected.
Operate the electric drill with the cord plug of the electric drill (not shown) connected. When the cone of the electric drill comes into contact with a metal object (not shown), the detection means detects and the alarm device 5 sounds, and the power cutoff means operates to cut off the power circuit of the electric drill. There is. This prevents accidents such as cutting of the electric wire in the buried pipe and accidents of damaging the cone of the electric drill.

[0007]

By the way, in the above-mentioned conventional metal detecting device 2 for an electric drill, an operator drills the electric drill at a place where the metal detecting device 2 is installed, that is, a place far away from the cord reel 1. Since the work is carried out using the cord reel 1 every time the power interruption means is activated.
The power supply circuit must be moved all the way up to release the cutoff state of the power supply circuit, and there is a problem that the release of the cutoff state is bothersome and the work efficiency is reduced.

The present invention has been made in view of the above circumstances in the prior art, and an object thereof is to detect a metal which enables an operator to easily and quickly release the cutoff state of the power circuit of the electric drill. It is to provide an electric drill with a device.

[0009]

In order to achieve this object, the present invention provides a detection means for detecting that the cone of an electric drill has contacted a metal object, and the electric drill according to the detection of the detection means. The power supply circuit is provided with a power supply cutoff means for cutting off the power supply circuit, and a reset contact for releasing the cutoff state of the power supply circuit is provided in association with the operation switch for driving the electric drill.

[0010]

Since the present invention is configured as described above, when the worker uses the electric drill with the metal detecting device, the power cut-off means is activated by the contact with the metal object to cut off the power supply circuit of the motor. At this time, when the operation switch for driving the electric drill is released, the reset contact interlocking with the operation switch is broken, the power cutoff means returns to the initial state, and the cutoff state of the power supply circuit is released. This eliminates the need for the operator to move to the cord reel when releasing the cutoff state of the power circuit of the electric drill, and therefore, the cutoff state can be released easily and quickly. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electric drill with a metal detector of the present invention will be described below with reference to the drawings.

FIG. 1 is an electric circuit diagram showing an embodiment of an electric drill with a metal detector according to the present invention, and FIG. 2 is an overall configuration diagram of the electric drill with a metal detector of FIG.

The electric drill 10 shown in FIG. 2 has a cone 11 and an operation switch 12, and a cord 13 has a metal detecting device 15 attached thereto.
Through the plug 14 to the commercial power outlet 16. As shown in FIG. 1, inside the electric drill 10, a motor M operated by electricity supplied from AC power supplies R and S and the motor M and the AC power supply R are provided, and the operation switch described above is provided. The normally open contact 12a that is closed by pressing the switch 12 and the motor M and the AC power supply S are interposed between the normally open contact 12a and the normally open contact 12a that is closed by the pressing operation of the operation switch 12. A terminal E electrically connected to the contact 22a and the cone 11
It has and.

The metal detecting device 15 of the present embodiment shown in FIG. 2 is provided on the cord 13 of the electric drill 10 as shown in FIG. 2, and as shown in FIG. Detecting means 2 for detecting that a person has touched a metal object
4 and the electric drill 10 according to the detection of the detection means 24.
Power cutoff means 25 for cutting off the power supply circuit and holding means 26 for holding the cutoff operation of the power cutoff means 25.

The above-mentioned detecting means 24 includes a transformer 31 whose primary winding side is connected to AC power supplies R and S, and this transformer 3.
A photodiode 3 whose one end is connected to the terminal V on the secondary winding side of No. 1 and whose other end is connected to the terminal E via the resistor 32.
3 and a diode 34 connected in parallel with the photodiode 33 and passing a current in the opposite direction.

The holding means 26 described above has an AC power source S on the input side, a normally-open contact 22a for resetting, and a relay 35.
Via a diode bridge 36 connected to the AC power supply R, a photothyristor 37 supplied with current from the diode bridge 36, and the photothyristor 3
The resistors 38, 39 and the capacitor 40 for maintaining the power supply of No. 7 are provided.

The above-mentioned power cut-off means 25 comprises the relay 35 and a normally-closed contact 35b interposed between the AC power source S and the motor M and opened by the bias of the relay 35. Further, the alarm device 5 is connected to a normally open contact 35 a which is closed by the bias of the relay 35.

In this embodiment, when an operator (not shown) presses the operation switch 12 of the electric drill 10 when using the electric drill 10, the normally open contact 12a is closed and the AC power source S-normally closed contact 35b. -Motor M-Normally open contact 12a
The circuit of the AC power supply R is closed, as a result of which the motor M is activated and the cone 11 is rotationally driven. Therefore, an operator (not shown) presses the cone 11 against, for example, a wall (not shown) to open a hole.

When the cone 11 contacts a metal object (not shown) embedded in the wall (not shown), the transformer 3
1 terminal V on the secondary winding side-photodiode 33-resistor 32-terminal E-cone 11-metal object (not shown) -grounding body GND-terminal U on the secondary winding side of transformer 31 The circuit is closed and the photodiode 33 emits light, which turns on the photothyristor 37. Along with this, the AC power source S-the normally open contact 22a closed by the pressing operation-
The circuit of relay 35-diode bridge 36-photothyristor 37-resistor 39-diode bridge 36-AC power supply R is closed, relay 35 is energized, and photothyristor 37 is actuated by the action of resistors 38, 39 and capacitor 40. Keeps turning on. The relay 35
The normally closed contact 35b is opened to stop the motor M, and the normally open contact 35a is closed to cause the alarm 5 to sound.

Next, an operator (not shown) makes the electric drill 1
When the operation of the operation switch 12 of 0 is stopped, the normally open contact 12a of the operation switch 12 is opened, and the photo-thyristor 3 is opened by opening the normally open contact 22a for resetting.
The current flowing through 7 is cut off, and this photothyristor 37
Turns off and relay 35 deactivates. With this,
The normally open contact 35a is opened to stop the alarm 5 from ringing, the normally closed contact 35b is closed, and the electric power is supplied to the motor M of the electric drill 10 again. However, since the contact 12a is open, the motor M does not rotate. Therefore, an operator (not shown) checks the metal object (not shown) with which the cone 11 has come into contact, determines whether to restart or stop the drilling work, and then restarts the drilling work. When 12 is operated again, the motor M is started.

In the embodiment thus constructed, when the power supply circuit of the electric drill 10 is released from the cutoff state, it is not necessary for an operator (not shown) to move to the cord reel 1 shown in FIG. In addition, the cutoff state can be released quickly.

In this embodiment, the holding means for holding the exciting operation of the relay 35 is provided with the photothyristor 37 or the like. However, instead of the photothyristor 37, a contact for self-holding of the relay 35 is provided, and this self-holding contact is provided. The holding contact may hold the exciting operation of the relay 35, or a microcomputer may be provided and the exciting operation of the relay 35 may be held under the control of the microcomputer. Further, although the metal detection device 15 is provided between the plugs 13 in the present embodiment, it may be built in and integrated with the electric drill.

[0023]

Since the present invention is configured as described above, it is not necessary for the worker to move to the cord reel when releasing the cutoff state of the power circuit of the electric drill. Therefore, it is easy and quick. It is possible to release the above-mentioned cutoff state, and therefore, it is possible to reduce the inconvenience when performing work using the electric drill and to improve the work efficiency.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of an electric drill with a metal detector of the present invention.

FIG. 2 is an overall configuration diagram of an electric drill with a metal detection device of FIG.

FIG. 3 is a perspective view of a conventional metal detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 code reel 10 electric drill 11 cone 12 operation switch 13 code 15 metal detection device 22a reset normally open contact 24 detection means 25 power cutoff means 26 holding means

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

Claims (1)

[Claims] 1. An electric drill, comprising: detection means for detecting that a cone of the electric drill has come into contact with a metal object; and power supply cutoff means for cutting off a power supply circuit of the electric drill in response to detection by the detection means. An electric drill with a metal detection device, characterized in that it is provided with a reset contact for interlocking with a driving operation switch for driving the power supply circuit.