JPH06143016A - Cutting control device - Google Patents

Abstract

PURPOSE:To provide a cutting controller for extending the life of a cutting tool by changing the load current of a main electric motor by means of the cutting tool diameter without switching operation, in the case of the cutting controller of a tool for rotation cutting such as drilling machine. CONSTITUTION:The exciting power of a feeding electric motor 4 is detected by a voltage detection circuit 19, and the feeding velocity is calculated by a microcomputer 25. When the feeding velocity is faster than a fixed level, the constant-current control value of a main electric motor 2 is re-calculated (Ic-Is), and the feeding velocity is controlled so that it does not exceed the fixed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting control device for a rotary cutting tool such as a drilling machine.

[0002]

2. Description of the Related Art In a conventional cutting tool, the load torque acting on the cutting tool changes in proportion to the feed speed of the cutting tool, and the load torque is proportional to the current of the main electric motor. The feed torque of the cutting tool is adjusted so that the current of (1) becomes a predetermined value, and the load torque is kept at a predetermined value. However, since the optimum load torque varies depending on the diameter of the cutting tool, a switch for changing the load current of the main electric motor is provided in the operating portion, and the feed speed during cutting is changed by switching the switch.

[0003]

In the above-mentioned prior art, there is a problem in that the operator needs to operate the switch in order to change the load current of the main electric motor according to the diameter of the cutting tool, and the switch operation is troublesome. Further, when the switch operation is mistaken and a small-diameter cutting tool is cut with a large load torque, the feed rate becomes too fast and the life of the cutting tool is shortened.

An object of the present invention is to provide a cutting control device which overcomes the above problems and which can change the load current of a main electric motor according to the diameter of the cutting tool without a switch operation to prolong the life of the cutting tool. .

[0005]

In order to solve the above-mentioned problems, the present invention detects the rotation speed of the feed motor and controls the current of the feed motor so that the feed speed of the cutting tool exceeds a predetermined value. Try not to.

[0006]

In the cutting control device of the present invention configured as described above, by setting the maximum value for the feed rate, the control value of the main motor current can be reduced and the life can be extended even with a cutting tool having a small diameter without operating a switch.

[0007]

1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a flow chart showing the control procedure of the present invention in FIG. The operation of the circuit shown in FIG. 1 will be described below according to the procedure of FIG.

The start in FIG. 2 corresponds to the procedure of fixing the cutting tool 7 to the electric drill 3 and turning on the power switch 9 and the drill switch 10. When the power switch 9 is turned on, the AC power source 8 is rectified by the rectifying bridge 11, and a current is passed through the electromagnetic coil 12 to attract and fix the object to be drilled. When the drill switch 10 is turned on, the power circuit 24
And the microcomputer 25 starts operating.

In step 401, the microcomputer 2
When the motor 5 starts its operation, it transmits a constant speed rotation signal of the main motor 2 to the semiconductor control element 13 in the order of the output port 255, the driver 26 and the ignition circuit 15 to rotate the main motor 2 at a constant rotation speed.

In step 402, the starting current of the main motor 2 is detected by the current detector 22, converted into a digital signal by the analog / digital converter 256, and transmitted to the microcomputer 25. As a result, the microcomputer 25 detects the end of the starting current and shifts to the next procedure.

Since the no-load current of the main motor 2 is detected after the start-up current is finished, the no-load current In is stored in step 403.

In the next step 404, the microcomputer 25 uses the current value I corresponding to the actual constant torque cutting.
constant current control value of the main motor 2 (In + It)
To calculate.

In the next step 405, the feed motor 4 is controlled to lower the electric drill 3. In this operation, the driver 2 is output from the output port 255 in the microcomputer 25.
6. The control signal is transmitted to the semiconductor control element 14 via the ignition circuit 16, and the feed motor 4 is driven.

In the next step 406, the start of punching of the object to be punched is detected from the change in the electric current of the main motor 2.

When the start of drilling is detected, in step 406, the feed motor 4 controls the current of the main motor 2. That is, when the current of the main motor 2 increases, the feed motor 4
To reduce the load on the cutting tool 7, and conversely, when the current of the main motor 2 decreases, the feed motor 4 is accelerated to increase the load on the cutting tool 7 to increase the current of the main motor 2. Is maintained at a predetermined value.

The feed motor 4 is a DC motor, and the rotation speed and the back electromotive force are proportional. In step 409, the voltage detector 19
Thus, the back electromotive force of the feed motor 4 is detected, converted into a digital signal through the voltage / frequency conversion circuit 21, and transmitted to the microcomputer 25. Microcomputer 2
5, the feed speed is calculated, and when the feed speed is faster than a predetermined value, the constant current control value of the main motor 2 is recalculated (Ic-Is), and the feed speed is controlled so as not to exceed the predetermined value. The Is may be a value stored in the memory device corresponding to the cutting condition, or may be calculated from the cutting condition according to a predetermined arithmetic expression.

In the next step 410, the return of the no-load current of the main motor current is detected and the drilling is ended.

[0018]

According to the present invention, even with a cutting tool having a small diameter, the feed rate is not increased more than necessary, so that the life of the cutting tool can be extended.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of a cutting control device according to the present invention.

FIG. 2 is a flowchart of an embodiment of the present invention.

FIG. 3 is an external view of a cutting device according to the present invention.

FIG. 4 is a cutting characteristic according to the present invention.

[Explanation of symbols]

1 is a drill stand, 2 is a main motor, 3 is an electric drill,
4 is a feed motor, 5 is a control box, 6 is an electromagnetic base,
7 is a cutting tool, 8 is an AC power supply, 9 is a power switch, 10
Is a drill switch, 11 is a rectifying bridge, 12 is an electromagnetic coil, 13 and 14 are semiconductor control elements, 15 and 1
6 is each firing circuit, 17 is a limit switch, 18 is a rectifier bridge, 19 is a voltage detection circuit, 20 is a relay, 21 is a voltage / frequency conversion circuit, 22 is a current detection circuit, 23 is a rotation signal generation circuit, and 24 is A power supply circuit, 25 is a microcomputer, and 26 is a driver.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Sudo 1060 Takeda, Katsuta-shi, Ibaraki Hitachi Koki Co., Ltd. (72) Inventor Kenji Kataoka 1060 Takeda, Katsuta-shi, Ibaraki Hitachi Koki Co., Ltd.

Claims (1)

[Claims] 1. An electric drill supporting a main electric motor and a cutting tool by a feed electric motor such that a main electric motor rotates a cutting tool, the electric current of the main electric motor is detected, and the electric current of the main electric motor has a predetermined current value. In a cutting device that moves a part to perform cutting, a speed detection unit that detects a feed speed of the cutting tool, and a feed current of the cutting tool becomes a predetermined speed value or more, a predetermined current value of the main motor A cutting control device comprising a control circuit for lowering the cutting.