JPH08108306A - Cutting controller - Google Patents

Abstract

PURPOSE: To put back an electric drill to a specified position, when the drilling work is over, at a high speed and using less expensive construction in a cutting controller for a rotational cutting tool like a drilling machine. CONSTITUTION: An electric current Ic of a stepping motor 4 is detected by a current detecting circuit 19. The result is compared with a step-out threshod value Ir, which is larger than the normal current value, by a microcomputer 21. If Ic>Ir, a controller is judged to be out of step, and both a full speed and an acceleration gradient of a feed motor are reset in order to restart the stepping motor 4.

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, an electric drill portion is returned to a predetermined position at high speed after the completion of the cutting work in order to shorten the working time of the entire cutting work. Since there is a large speed difference between the feed speed during cutting (10 to 50 mm / min) and the high speed return speed after cutting (1000 mm / min or more), if a commutator motor or DC motor is used as the feed motor, It is difficult to return the electric drill part at high speed only by speed control, and the electric drill part is returned at high speed by changing the gear ratio of the feed mechanism part after finishing the cutting process.
Also, if a stepping motor is used for the feed motor, speed control over a wide range is possible, and high speed return is realized without a complicated gear speed change mechanism.

[0003]

In the above-mentioned prior art, when the stepping motor is used as the feed motor, the maximum speed is lower than that of other motors, and therefore the gear ratio of the feed mechanism is required to return the electric drill at high speed. Is required to be small, and a large torque is required for the stepping motor. However, in the high rotation range, the torque generated by the electric motor becomes small and the margin torque becomes small. The load torque of the feed mechanism changes due to play in the feed mechanism and changes in the viscosity of the lubricating oil.If the load torque exceeds the torque generated by the electric motor, step out occurs and the rotation of the stepping motor stops, causing the electric drill to stop. There was a problem that it could not be returned to the predetermined position.

An object of the present invention is to overcome the above problems, detect step-out of a stepping motor, change the maximum speed and acceleration gradient, restart the stepping motor, and quickly return the electric drill to a predetermined position. It is to provide a cutting control device capable of performing.

[0005]

In order to solve the above problems, the present invention detects the current of the stepping motor,
The stepping motor is discriminated from the current of the stepping motor, and when the stepping step is lost, the maximum speed is lowered and the acceleration gradient is made gentle to restart the stepping motor.

[0006]

The cutting control device of the present invention configured as described above can return the electric drill unit to a predetermined position at high speed regardless of the load fluctuation of the feed mechanism unit.

[0007]

FIG. 1 is a circuit diagram of an embodiment of the present invention. 1
Is a drill stand, 2 is a main motor, 3 is an electric drill, 4
Is a stepping 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 is a semiconductor control element, 14 is a limit switch, 15 is a DC power supply for a stepping motor, 16
Is a stepping motor drive element, 17 is an ignition circuit, 18
Reference numerals 19 and 19 are current detection circuits, 20 is a power supply circuit, 21 is a microcomputer, and 22 is a driver. FIG. 2 is a flowchart 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 20
And the microcomputer 21 starts operating.

In step 401, the microcomputer 2
When No. 1 starts the operation, the constant speed rotation signal of the main motor 2 is transmitted to the semiconductor control element 13 in the order of the output port 215, the driver 22 and the ignition circuit 17 to rotate the main motor 2 at a constant rotation speed.

In step 402, the stepping motor 4 is controlled to lower the electric drill 3. In this operation, a control signal is transmitted from the output port 217 in the microcomputer 21 to the stepping motor drive element 16 to drive the stepping motor 4. The stepping motor drive element 16 has a built-in current control function, and controls so that the stepping motor drive current does not exceed a preset current.

In step 403, the start of punching of the object to be punched is detected from the change in the electric current of the main motor 2.

In step 404, the return of the no-load current of the main motor current is detected, and the boring is ended.

When the end of drilling is detected, the procedure goes to step 405 and thereafter to move the electric drill 3 up at a high speed.

In step 405, the maximum speed and acceleration gradient data of the stepping motor 4 at the time of high speed return, which are stored in the microcomputer 21 in advance, are read out.

In step 406, the stepping motor 4 is rotated in reverse according to the set acceleration gradient, and the electric drill 3 is raised.

In step 407, it is detected whether or not the electric drill 3 has risen to a predetermined position due to the opening of the limit switch 14. Step 41 when you reach the specified position
1, the stepping motor 4 sent from the microcomputer 21 to the semiconductor control element 13 to the drive signal of the main motor 2 and the stepping motor drive element 16 is sent.
Drive signal is stopped, the main motor 2 and the stepping motor 4 are stopped, and the processing is ended.

In step 408, it is determined whether or not the speed of the stepping motor 4 has reached a preset maximum speed. If the maximum speed is reached, the next processing is started.

In step 409, the current Ic of the stepping motor 4 is detected by the current detection circuit 19, converted into a digital signal by the analog / digital converter 216, and transmitted to the microcomputer 21. There is a difference as shown in FIG. 4 between the current waveform when the stepping motor 4 is rotating at high speed and the current waveform when the stepping motor 4 is out of step and stops rotating. Especially when rotating at high speed, the current does not rise sufficiently and the peak is suppressed. By detecting the difference between the current waveforms, it is determined whether or not there is a step out. A value slightly larger than the peak value of the normal current waveform is detected as the step-out detection threshold Ir.
Is stored in the microcomputer 21 in advance and compared with the current Ic of the stepping motor 4 detected through the current detection circuit 19. When the stepping motor current Ic is larger than the threshold value Ir, it is determined that the step is out of step, and the procedure proceeds to the next step.

In step 410, the maximum speed is set low and the acceleration gradient is gently set again so that the stepping motor 4 does not step out again. The reset maximum speed and acceleration gradient may be values stored in the memory device corresponding to the cutting conditions or calculated from the above cutting conditions according to a predetermined arithmetic expression.

Next, returning to step 406, the stepping motor 4 is restarted to raise the electric drill 3 to a predetermined position.

[0021]

According to the present invention, the electric drill unit can be returned to the predetermined position at high speed regardless of the load fluctuation of the feed mechanism unit.

[Brief description of drawings]

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

FIG. 2 is a flowchart according to the present invention.

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

FIG. 4 is a current waveform of a stepping motor according to the present invention.

[Explanation of symbols]

Reference numeral 2 is a main electric motor, 3 is an electric drill, 4 is a stepping motor, 7 is a cutting tool, 19 is a current detection means, 216 is a step-out determination means, and 217 is a speed control means.

Claims (2)

[Claims] 1. A cutting tool is rotated by a main electric motor, and an electric drill portion supporting the main electric motor and the cutting tool is moved by a stepping motor to perform cutting work. After the cutting work is completed, the electric drill portion is moved to a predetermined position. In the cutting control device for returning to the position, current detection means for detecting the current of the stepping motor, step-out determination means for determining step-out of the stepping motor based on a signal from the current detection means, and step-out determination means A cutting control device comprising: speed control means for reducing the return speed to a predetermined speed or restarting the stepping motor according to the step-out determination. 2. The cutting control device according to claim 1, further comprising speed control means for gently accelerating the acceleration gradient of the stepping motor when the step-out determination means restarts by the step-out determination.