JPS62213909A - Drill - Google Patents

Abstract

PURPOSE:To dispense with the setup of a position sensor and simplify a drill in structure, by detecting a current variation in a drill motor, and also detecting a cutting end of the drill. CONSTITUTION:Avoiding a starting current, the no-load current value is stored by a punching end discriminating system. On the basis of this no-load current, whether it is during drilling or completion or not is discriminated. When punching is started by a drill 9, a current in a drill motor 2 is increased, and the current is monitored by a current detector. When the drilling is cover, a fact that the current comes into a no-load state is detected so that drill rotation is stopped by the drilling end discriminating system, and a feed motor 4 is turned to a reverse mode, whereby a drill 3 goes up and stops, thus drilling operation comes to an end.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an electric motor that drives an awl built into an electric drill (hereinafter referred to as an awl motor), and a feed motor that moves the electric drill up and down along a drill stand. The present invention relates to a drilling machine having a circuit for controlling the same.・ [Background of the Invention] Conventionally, when drilling an object automatically, an electric drill mounted on a drill stand is lowered by a feed motor, and a limit switch for detecting completion of drilling installed at the drilling completion position is operated. , the drill motor and feed motor were stopped. However, each time a drill of different length is changed, and each time the thickness of the object to be drilled is changed, the drilling end position changes, so the position of the limit switch for detecting the completion of drilling must be adjusted. Furthermore, the configuration of the drilling machine becomes complicated due to the installation of a limit switch for detecting completion of drilling.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, improve operability, and simplify the construction of a drilling machine.

[Summary of the invention]

In the present invention, the current flowing through the drill motor is large during cutting,
Focusing on the point that the no-load current on the cutting surface returns when cutting is completed, the completion of cutting by the drilling machine is detected by detecting the current flowing through the drill motor.

[Embodiments of the invention]

FIG. 1 is an overview diagram showing one embodiment of the present invention, and FIG. 2 is a circuit diagram showing one embodiment of the present invention. In the figure, 1 is a drill stand, 2 is a drill motor that rotates a drill bit 9, 2 is an electric dowel IJ with built-in drill motor 2, and 4 is a field winding 4'.
The electric drill 3 is raised and lowered along the drill stand 1 by a feed motor consisting of a motor and an armature winding 4''. 5 is a control box containing a circuit for controlling the drill motor 2 and the feed motor 4, and 6 is an electromagnetic coil. 7 is 1
A switching knob that turns on the power switch 10 in step operation and turns on the automatic switch 11 in two step operation; 8 is a cone motor 2;
and a rotation speed setting knob that sets the rotation speed of the feed motor 4, and a single-shaft dual variable resistor 182.192 is attached.
The rotational speed of the drill motor 2 and feed motor 4 (lowering speed of the electric drill 3) is set in accordance with the drill diameter. 12 is a rectifier bridge, 14.15 is a semiconductor control element that controls the voltage supplied to the cone motor 2 and the feed motor 4, and 16
．． 17 is a speed control circuit that controls the rotation speed of the drill motor 2 and the feed motor 4, and is a simple open-loop control phase control circuit or a constant speed control circuit that performs constant speed control by feeding the rotation signal from the motor. Consisting of 18 is a rotation speed setting circuit for setting the rotation speed of the drill motor 2, and a resistor 181
．． 183 and a variable resistor 182. 19 is a rotation speed setting circuit for setting the rotation speed of the feed motor 4, and a resistor 191
．． 193 and a variable resistor 192. 20.21 is an operation control circuit that controls the operation of the speed control circuit 16.17;
A current detector 22 detects the current flowing through the cone motor 2, and is composed of a current transformer and the like. 23 is a signal conversion circuit that converts the current flowing through the conical motor 2 into a DC signal according to the magnitude of the current, and includes resistors 231, 234, 235, capacitors 232, 236,
It consists of a rectifying bridge 233. 24 is an A/D converter that converts an analog signal into a digital signal; 25 is an A/D converter that converts an analog signal into a digital signal; A drilling completion determination system that determines whether drilling is in progress or completed based on the load current value and outputs a signal to control the operation of the drill motor 2 and feed motor 4. CPU, ROM, RAM, external input/output ■ 10 boards Consists of a single-chip micro converter unit with a built-in. 26 is a driver IC 127 that receives a signal from the drilling completion determination system 25 and drives an external element; and a driver IC 127 that rotates the feed motor 4 in the forward and reverse directions (lowers and raises the electric drill); and a relay coil that switches between relay contacts 27' and 27'; 28 is a relay coil that switches between relay contacts 28' and 28'' for rotating and braking the feed motor 4; 29 is an upper limit switch that sets the electric drill 3 attached to the drill stand 1 to a rising stop position; 30 is a semiconductor control element 15, the maximum voltage is applied to the feed motor 4, and the motor full speed control circuit rotates the feed motor 4 at full speed.
303, consists of a photorelay 302. 31 is a brake resistor for the feed motor 4, and 32 is a drilling completion determination system 2.
5. A power supply circuit that serves as a power source for the A/D converter 24, etc., including a transformer 321, a rectifier bridge 322, and a smoothing capacitor 3
23. Consists of 3-terminal constant voltage IC324.

The operation will be explained based on the drill motor current characteristic diagram during drilling shown in FIG. 3 and the operation flowchart of the drilling completion determination system shown in FIG. 4. After fixing the drill bit 9 to the electric drill 3 and turning the rotation speed setting knob to a position corresponding to the drill diameter, turning the switching knob 7 and turning on the power switch 10, the electromagnetic coil 13 is excited and the electromagnetic base 6 is turned on. It is adsorbed to the object to be drilled. Furthermore, when the switching knob 7 is turned and the automatic switch 11 is turned on, the drilling completion determination system 25 outputs an operation signal to the operation control circuit 20 through the driver IC 26, operates the speed control circuit 16, and adjusts the drill motor 2 to the used drill diameter. Rotate at the corresponding rotation speed. At the same time, the drilling completion determination system 2
5 monitors the current flowing through the conical motor 2 from a current detector 22 through a signal conversion circuit 23 and an A/D converter 24;
If it is detected that it is not the starting current (there is no change in current),
The current value (no-load current value) from the A/D converter 24 is stored. In the above method, as a method of not inputting the starting current value, there is also a method of not detecting the current while the starting current is flowing. Next, the drilling completion determination system 2
5 energizes the relay coil 28 through the driver IC 26, switches the relay contacts α28' and 28' to the normally open contact side, outputs an operating signal to the operation control circuit 21, operates the speed control circuit 17, and operates the electric drill. The feed motor 4 is rotated so that the feed motor 3 descends at a descending speed corresponding to the diameter of the drill used. When the electric drill 3 descends and drills the object to be drilled, the drill motor current increases. When drilling is finished, the drill motor current returns to the original no-load current. Drilling completion determination system 25
determines the drilling state based on the stored no-load current value, and when it detects the completion of drilling, stops outputting the operation signal to the operation control circuit 20 through the driver IC 26,
At the same time, the relay coil 28 is deenergized, and the relay contacts 28',
28'' to the normally closed contact side, brakes the feed motor 4 to stop it, and stops the operation of the speed control circuit 16. Next, the relay fill 27 is energized and the relay contact 2
7' and 27'' to the normally open contact side, put the feed motor 4 in reverse mode, and operate the motor full speed control circuit 30.
Raise the electric drill 3 to full speed. When the electric drill 3 rises and the limit switch 29 is activated, the relay coil 2
8 is deenergized, the relay contacts 28' and 28' are switched to the normally closed contact side, the feed motor 4 is braked and stopped, the electric drill 3 stops rising, and the drilling operation is completed.

〔Effect of the invention〕

According to the present invention, since drilling is detected by detecting changes in the current of the drill bit motor, there is no need to install a position sensor such as a limit switch, and the configuration of the drilling machine is simplified. Furthermore, since there is no need to adjust the position sensor, it becomes easier to operate.

[Brief explanation of drawings]

Fig. 1 is an overview perspective view showing an embodiment of the present invention, Fig. 2 is a circuit diagram showing an embodiment of the present invention, Fig. 3 is a current characteristic diagram of a drill motor during drilling, and Fig. 4 is a diagram showing an embodiment of the present invention. This is a 70-part chart of the operation of the drilling completion determination system. In the figure, 1 is a drill stand, 2 is a drill motor, 3 is an electric drill, 4 is a feed motor, 11 is an automatic switch, 22 is a current detector,
23 is a signal conversion circuit, 25 is a drilling completion determination system, 2
9 is an upper limit switch, 30 is a motor full speed control circuit, and 192 and 193 are variable resistors. Name of patent applicant Hitachi Koki Co., Ltd.

Claims (1)

[Claims] 1. A drill motor that rotates a drill bit, an electric drill incorporating the drill motor, a feed motor that moves the electric drill down along a drill stand to drill a hole in the object to be drilled, and a current of the drill motor. a current detector that detects the signal, a signal conversion circuit that converts the signal of the current detector to a DC level, and when the automatic switch is turned on, the no-load current value from the signal conversion circuit is controlled to avoid the starting current of the conical motor. A drilling machine equipped with a drilling completion determination system that stores data and determines whether drilling is in progress or completed based on the no-load current value. 2. At the end of drilling, the feed motor is stopped to stop the electric drill from descending, and then the feed motor is reversed to raise the electric drill, and when the upper limit switch is activated, the electric drill stops from rising. drilling machine. 3. Drilling is performed at the rotational speed of the feed motor (lowering speed of the electric drill) corresponding to the drill diameter, and after the drilling is completed, the electric drill is raised at the maximum speed by a motor full speed control circuit. drilling machine. 4. The drilling machine according to claim 1, wherein the drill motor and the feed motor are stopped at the end of drilling. 5. The drilling machine according to claim 1, wherein the rotation speed of the drill motor and the rotation speed of the feed motor (lowering speed of the electric drill) corresponding to the drill diameter can be set using a single shaft and two sets of variable resistors. .