JPH03213246A - Cutting control device - Google Patents

Abstract

PURPOSE:To perform machining with optimum cutting torque by performing control with a cutting main electric motor current, in which a no-load current and a load current necessary for cutting are added, in the case of a control device for a rotary cutting tool of a drilling machine or the like. CONSTITUTION:A main electric motor 2 is rotated at a fixed rotational speed by outputting a fixed speed rotational signal of the main electric motor 2 by a microcomputer 24 to actuate a semiconductor control element 14 by an ignition circuit 16. A fixed current control value (In+It) of the main electric motor 2 is calculated by detecting a no-load steady current In, continued to a starting current, by a current detector 22 and calculating a current It corresponding to the actual fixed torque cutting. Next a feed electric motor 4 is driven, and a start of drilling is confirmed from a current increase of the main electric motor 2. A current of the main electric motor 2 is held to a predetermined value by reducing a speed of the feed electric motor 4 when the current of the main electric motor 2 is increased. The feed electric motor 4 is stopped and reversed by detecting resetting to the no-load current In of the main electric motor 2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a control device for a rotary cutting tool such as a drilling machine, and particularly relates to a cutting control device that can optimally and automatically control cutting torque. .

[Conventional technology]

In conventional cutting tools, an electric drill equipped with a cutting tool rotated by a main electric motor, a switch panel, etc. is supported by a drill stand, and cutting feed is given by a feed motor. Further, the object to be drilled is electromagnetically attracted and fixed.

In the conventional cutting tool described above, the load torque acting on the cutting tool changes in proportion to the feed rate of the cutting tool, and furthermore, the load torque is proportional to the current of the main motor.
The feed rate of the cutting tool is adjusted so that the current of the main motor becomes a predetermined value, and the load torque is maintained at a predetermined value.

[Problem to be solved by the invention]

In the above conventional technology, various bearings, feeding devices,
As the viscosity of the lubricating oil used in gear mechanisms changes due to temperature and other factors, the mechanical loss changes, which causes the load torque to change, making the cutting tool less sharp and shortening its life. there were.

An object of the present invention is to provide a cutting control device that can compensate for mechanical loss fluctuations in the cutting tool, improve the sharpness of the cutting tool, and extend the life of the tool.

[Means for Solving the Problems] In order to solve the above problems, the present invention detects the current of the main motor to determine the load torque value, and controls the current of the transmission motor to determine the load torque value. Make sure to keep it at the specified value.

Further, the no-load current of the traction motor detected by the current detector and the load current component of the traction motor defined for the load torque value are added, and the added value and the current detector detect the added value. The transmission motor current is controlled by comparing the main motor load current with the main motor load current.

Furthermore, the no-load current is detected by the current detector after the pulsed starting current of the main motor ends.

[Effect]

The cutting control device of the present invention configured as described above controls the current value obtained by adding the no-load current not involved in the actual cutting process and the load current necessary for the actual cutting process as the main motor current for the cutting process. So.

Cutting torque can be set accurately to the required value.

Furthermore, since the feed rate of the cutting tool is controlled to maintain the added current value at a predetermined value, fluctuations in the cutting torque are prevented.

〔Example〕

FIG. 1 is a circuit diagram of one embodiment of the present invention, and 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 explained below according to the procedure shown in FIG.

At the start in Fig. 2, the cutting tool 8 is inserted into the electric drill 3.
When the power switch 10 is turned on, the power supply 9 is rectified by the rectifier bridge 12, and current flows through the electromagnetic coil 13. The object to be drilled is fixed by suction.

Next, in step 401 of FIG. 2, when the switching knob 7 is moved to the automatic switch side and the automatic switch 11 of FIG. 1 is closed,
The automatic switch detection means 111 detects the on state of the automatic switch 11 and detects the on state of the automatic switch 11 and outputs the input port 2 of the microcomputer 24.
Tell 47. Accordingly, the microcomputer 24
transmits a constant speed rotation signal of the main motor 2 to the semiconductor control element 14 in this order through the output port 248, the driver 25, and the ignition circuit 16 to rotate the main motor 2 at a constant rotation speed. At this time, the cutting tool 8 is not in contact with the object to be cut yet, and the constant speed rotation signal is applied to the light emitting element in the optical coupling element 162 via the resistor 161 in the ignition circuit 16, causing it to emit light. ,
It is converted into an electric signal by the light receiving element and sent to the semiconductor control element 1.
Applied to the gate of 4.

In step 402 in FIG. 2, the starting current of the main motor 2 is detected by the current detector 22, rectified, smoothed and level-converted by the signal conversion circuit 23, and converted into a digital signal by the analog/digital converter 245. The information is transmitted to the microcomputer 24.

As a result, the microcomputer 24 detects the end of the starting current and proceeds to the next step 403.

FIG. 3 shows the current waveform of the main motor current.

A pulse-like starting current occurs immediately after startup, and then a no-load current flows.

After the above-mentioned starting current ends, the no-load steady-state current of the main motor 2 is detected, so in step 1 403, the above-mentioned no-load steady-state current I
Memorize n. Note that it is also possible to stop the current detection operation for a predetermined time longer than the generation period of the starting current, and then detect the no-load steady current In.

In the next step 404, the microcomputer 24 calculates a current value It corresponding to actual constant torque cutting, and calculates a constant current control value (In+It) of the main motor. The above-mentioned It may be a value stored in a memory device corresponding to the cutting conditions, or may be calculated from the above-mentioned cutting conditions according to a predetermined arithmetic expression. The above (In + It) corresponds to the current value from the start of drilling to the end of drilling in FIG.
lower. In this operation, the microcomputer 24
Output port 248 in driver 251 ignition circuit 17
A control signal is sent to the semiconductor control element 15 via the semiconductor control element 15, and the sending motor 4 is driven. The circuit configuration of the ignition circuit 17 is similar to that of the ignition circuit 16.

In the next step 406, the start of drilling of the object to be drilled is detected from an increase in the current of the main motor 2.

In the next step M407, the current control of the main motor 2 by the transmission motor 4 is performed. That is, when the current of the main motor 2 increases, the feed motor 4 is decelerated to reduce the load on the cutting tool, and conversely, when the current of the main motor 2 decreases, the feed motor 4 is accelerated to reduce the load on the cutting tool. The current of the main motor 2 is maintained at a predetermined value by increasing this load.

In the next step 408, the above no-load current I of the traction motor current is
n return is detected and the sending motor 4 is stopped in Step 1 409. In stopping the feed motor 4, the drive signal for the feed motor 4 sent from the microcomputer 24 to the semiconductor control element 15 is stopped, and at the same time, the relay 27 is switched to the normally closed contact side to control the feed motor 4. Note that 271 is the relay 27 driven by the driver 25.
This is the drive coil.

In the blowing step 410, the electric drill 3 is raised by reversing the feed motor 4. In this operation, the relay 26 is driven via the driver 25 according to a command from the microcomputer 24.

In the next step 411, it is detected that the electric drill 3 has risen and the limit switch 18 has been activated. The actuation signal is detected by the upper limit switch state detection means 181 and input to the microcomputer 24 via the input port 247.

In the next step 412, the rising signal of the feed motor @4 sent from the microcomputer 24 to the semiconductor control element 15 is stopped, and at the same time, the relay 27 is switched to the normally closed contact side to brake and stop the feed motor 4, and the drilling process is performed. end.

FIG. 4 is an example of an external view of the cutting tool according to the present invention. In FIG. 4, a drill stand 1 shows an electric drill 2 equipped with a cutting tool 8 rotated by a main electric motor 2 and a switching knob 7 for turning on the power and switching an automatic switch.
The cutting feed is applied by a feed motor 4. At this time, the object to be drilled is electromagnetically attracted and fixed by the electromagnetic base 6.

In the apparatus according to the embodiment of the invention shown in FIG. 4, the control circuit according to the invention shown in FIG. The control box 5 and the feed motor 4 are newly provided parts according to the present invention.

〔Effect of the invention〕

According to the present invention, the main motor current for cutting is the sum of the no-load current that is not involved in the actual cutting and the load current necessary for the actual cutting, so the workpiece is adjusted to the optimum cutting torque. It can be processed using

Furthermore, since the feed rate of the cutting tool is controlled to maintain the added current value at the optimum value, fluctuations in the cutting torque can be prevented.

As a result, the efficiency of cutting can be improved and the life of the cutting tool can be extended at the same time.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of a cutting control device according to the present invention, and FIG. 2 is a flow chart of the embodiment of the present invention. FIG. 3 is a waveform diagram of cutting motor current according to the present invention, and FIG. 4 is an external view of the cutting device according to the present invention. 1 is a drill stand, 2 is a main motor, 3 is an electric drill,
4 is a sending motor, 5 is a control box, 6 is an electromagnetic base,
7 is a switching knob, 8 is a cutting tool, 9 is an AC power supply, 10 is a power switch, 11 is an automatic switch, 12 is a rectifier bridge, 13 is an electromagnetic coil, 14 and 15 are each semiconductor control element, 16 and 17 are each point arc circuit, 18 is an upper limit switch, 19 is a rotation signal generation circuit, 20 is a power supply circuit, 21 is a zero voltage detection circuit, 22 is a current detector, 23 is a signal conversion circuit, 24 is a microcomputer, 25 is a driver, 26 and 27 is a relay, and 28 is a brake resistor.

Claims (1)

[Claims] 1. In a cutting device that performs cutting by rotating a cutting tool by a main electric motor and moving an electric drill part that supports the main motor and the cutting tool by a feeding motor, the electric current of the main motor is A cutting control device comprising: a current detector for detecting the current; and a control circuit for controlling the current of the feed motor based on the output of the current detector. 2. Claim 1, further comprising: a storage device for the no-load current of the traction motor; and a storage device for the load current of the traction motor or an arithmetic device for calculating the load current; The load current value stored in the device or the load current value calculated by the arithmetic unit is added to the no-load current value stored in the no-load current storage device, and the added value and the traction motor load detected by the current detector are calculated. A cutting control device characterized in that the feed motor current is controlled by comparing the current with the current. 3. In claims 1 and 2, the control circuit has a function of identifying a pulsed starting current of the traction motor detected by a current detector of the traction motor, or a timer device that sets the generation time width of the starting current. A cutting control device comprising: detecting a no-load current of the main motor after the starting current ends.