JP2554921Y2 - Drilling machine safety equipment - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a drilling machine, and more particularly, to a drilling machine having a frame base provided with an electromagnet capable of being magnetically attracted to a workpiece. Or when the drive power supply system breaks down and the workpiece is incompletely attached to the workpiece and good magnetic attraction is not achieved, the electric drill motor (hereinafter referred to as drill motor) The present invention relates to a safety device for a drilling machine that can stop the rotation of a boring machine.

[0002]

2. Description of the Related Art An electromagnet is provided on a base of a frame for supporting an electric drill. The electromagnet is energized to magnetically attract a workpiece, and then a drill motor is energized to perform a drilling operation on the workpiece. Machines are conventionally known.

[0003]

In the conventional drilling machine as described above, the electromagnet itself for magnetic attraction and the power supply system for driving the electromagnet fail, and the magnetic force does not function sufficiently during the drilling operation. If the magnetic force is no longer generated,
Since the function of fixing the electric drill to the workpiece is lost, good drilling work cannot be continued, and it is extremely dangerous. As a countermeasure,
The applicant first mentioned in the invention of Japanese Utility Model Application Publication No. 54-92783.
Current-responsive relay that responds to the coil current of the attraction electromagnet.
Control the drill motor and feed motor using the
When the current drops below the predetermined value, stop the motor.
Proposed protection device. However, the coil current
Load fluctuation and power supply to the drill motor
Because the voltage fluctuates considerably significantly, in this example
Is difficult to set the current-sensitive relay
Vortex quality parts and custom products must be used for
It is said that it is easy to invite high cost and downsizing is difficult
There was a problem.

[0004] The present invention has been made to solve the problems described above, and its object is only possible not generated by necessary and sufficient force is an electromagnet for fixing the drilling machine to the workpiece Is connected in series to the coil of the lightning magnet for adsorption.
Is determined by the amount of voltage drop in the constant voltage element
An object of the present invention is to provide a safety device for a drilling machine that can immediately stop energization of a drill motor based on the same .

[0005]

In order to solve the above problems SUMMARY OF THE INVENTION The present invention is a means for detecting a current flowing to the electromagnet circuit is provided, the value of the current is out of the set range during the electric drill operation In this case, means for stopping the power supply to the drill motor is employed.

[0006]

[Function] If the coil of the magnetic attraction electromagnet or its related wiring is broken or contact failure occurs, the coil current abnormally decreases or becomes zero. Therefore, during the operation of the electric drill, the current flowing through the electromagnet circuit is monitored. And its associated wiring abnormalities are detected. When an abnormal current is detected in this way,
Turn off the power to the drill motor and stop the electric drill.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 3 is a perspective view showing a schematic configuration of a drilling machine suitable for applying the present invention. In this type of drilling machine, the frame 4 supporting the electric drill 43 so as to be able to move up and down.
An electromagnetic base 42 is attached to a lower portion of the housing 1, and an electromagnet 5 for magnetic attraction is housed inside the electromagnetic base 42. Frame 4
An electric drill 43, which can be moved up and down by either manual operation or electric operation, and a slide plate 46 fixed to the electric drill 43 are attached to the front of the electric drill. An annular blade 47 is attached to the arbor of the electric drill 43 downward. The feed motor 44 drives the electric drill 43 up and down via the slide plate 46.

The limit switch 45 includes a slide plate 46
Is operated by the slide plate 46 and stops the feed motor 44 when the electric drill 43 moves as the electric drill 43 descends and descends to a predetermined position. Operation handle 4
The main switch 3 and the electric drill 4 described later are driven in two stages by manual operation.
3. The feed motor 44 is operated.

FIG. 2 is a specific circuit diagram of an embodiment of the present invention. When the main switch 3 is turned on in the first stage by manual operation of the operation handle 40, the contacts 3A and 3B are connected and the power supply circuit of the electromagnet is closed, so that the rectifiers 4 and 13 are energized by the AC power supply 30. Due to the energization of the rectifier 4, a DC current flows through a series circuit of the diode array 11 and the electromagnet 5 formed of three (arbitrary numbers) diodes connected in series, and is substantially constant at both ends of the diode array 11. The potential difference V1 is generated. A series circuit of the light emitting element 12A of the photocoupler 12 and the resistor 21 is connected in parallel with the diode array 11, so that the light emitting element 12A emits light at a predetermined intensity.

At this time, since the rectifier 13 is also energized, a predetermined current flows through the light receiving element 12B of the photocoupler 12. As a result, a sufficient potential difference is generated between the two terminals of the resistor 15 connected between the first anode T1 and the gate G of the triac 14 (generally, an AC control element), and the triac 14 becomes conductive. As a result, the triac 14
A sufficient current for excitation flows through the relay 16 via the first and second anodes T1 and T2, and the normally open contact 16 of the relay 16
A is closed.

Thereafter, when the main switch 3 is turned on in the second stage and the contact 3C is further connected to the contact 3A, the drill motor 6 starts rotating with the power supply circuit closed to the electromagnet, and the drilling operation is started. Preparation is completed. In this state, the motor 4 4 sends an electric drill 4 3, or by lowering manually, it is possible to perform the drilling operation. During the drilling operation, the voltage and electromagnetic
Even if the current flowing through the stone 5 fluctuates, the potential difference V1 between both terminals of the diode array 11 hardly changes due to the characteristics of the diode, so that the operation state of the photocoupler 12 is stable.

During the drilling operation, the coil of the electromagnet 5 is disconnected or the rectifier 4 breaks down, so that the current of the electromagnet 5 is less than the set value (for example, it is not possible to magnetically attach the drill to the workpiece sufficiently strongly. Value) or becomes zero, the potential difference V1 between both terminals of the diode array 11 also becomes equal to or less than the set value or becomes zero. As a result, the light emitting element 12A of the photocoupler 12 stops emitting light, the light receiving element 12B is turned off, and no current flows to the input side of the rectifier 13.
At this time, there is no potential difference between the two terminals of the resistor 15, so that the conduction of the triac 14 is cut off and the relay 16
Is extinguished. Therefore, the contact 16A returns to the initial state (open), the power supply to the drill motor 6 is stopped, and the operation of the electric drill is stopped.

[0013] FIG. 1 is a functional block diagram of this invention.
2, the same reference numerals as those in FIG. 2 represent the same or equivalent parts. Current detecting means 51 is for detecting a current flowing through the electromagnet 5, as shown in FIG. 2,
Light emitting element 12A of diode 11 and photocoupler 12
And the like. When the current detection unit 51 detects the current flowing through the electromagnetic <br/> stone 5, the switching means 53 for controlling the current of the drill motor 6 is actuated to close the contacts 16A. As a result, the drill motor 6 is energized, and if the drill motor 6 is energized, the drilling operation can be performed.

The switching means 53 includes a light receiving element 12 B of the photocoupler 12, a rectifier 13, and a triac 14.
And a relay 16 having a normally open contact 16A. The current detecting means 51
Detects that no current is flowing through the electromagnet 5,
The switching means 53 is opened. Thus, the energization of the drill motor 6 is stopped, and the drilling operation is also stopped.

Various modifications can be made to the embodiment described above as follows. Instead of the diode array 11, any other suitable constant voltage element such as a Zener diode can be used. If the operating current of the relay 16 is not so large and the relay 16 is energized in response to the current of the light receiving element 12B of the photocoupler 12, the triac 14 and the resistor 15 are unnecessary. Further, instead of the relay contact 16A arranged in series with the drill motor 6, an electronic switch (for example, a solid switch) may be used. Reference numeral 16F is a voltage relay connected in parallel with the attraction electromagnet 5.

[0016]

[Effect of the Invention] According to the present invention , the core of the magnet for magnetic attraction is
In the event that the electric wire breaks or the power supply system for driving the electromagnet breaks down and the necessary and sufficient magnetic force is no longer generated for the drilling operation, power supply to the drill motor should be stopped immediately to stop the drilling operation. Therefore, the effect that the safety of the drilling machine can be ensured with a simple configuration is achieved.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of an embodiment of the present invention.

FIG. 2 is a specific circuit example of the embodiment shown in FIG. 1;

FIG. 3 is a perspective view showing a schematic configuration of a drilling machine suitable for applying the present invention.

[Explanation of symbols]

4 rectifier, 5 electromagnet, 6 drill motor, 1
DESCRIPTION OF SYMBOLS 1 ... Diode, 12 ... Photocoupler, 14 ... Triac, 16 ... Relay, 16A ... Contact, 51 ... Current detection means, 52 ... Potential difference detection means, 53 ... Switching means 1, 41 ... Frame, 42 ... Electromagnetic base,
43: Electric drill, 44: Feed motor

Claims (3)

(57) [Scope of request for utility model registration] An electric drill driven by a motor,
And a drilling machine provided with an electromagnet on a frame base for magnetically attracting a frame supporting the electric drill to be able to move up and down, at least one constant voltage element connected in series to the electromagnet
Wherein the child, and a photocoupler connected in parallel the constant voltage element, a current detecting means for detecting a current flowing through the electromagnet is energized by the output of the photocoupler, switching to ON ∠ off control of current flowing through the motor The switching means interrupts the current flowing to the motor in response to the output of the current detection means when the current detection means detects that no current flows to the electromagnet. A safety device for a drilling machine. 2. The safety device for a drilling machine according to claim 1, wherein said switching means includes relay means for interrupting a current flowing through said motor when an output of said photocoupler falls below a predetermined value. 3. The switching means includes a current control element which is connected in series with the relay means and is turned on / off in accordance with an output current of the photocoupler, and when the current control element is turned on, the relay means is provided. 3. The safety device for a drilling machine according to claim 1, wherein the motor is energized to supply a current to the motor.