KR0140670B1 - Wire free tension control system of wire cut machine - Google Patents

Abstract

The present invention relates to a wire pretension control device for a wire cut discharge machine, and in particular, between a pulley (2) and a recovery bobbin (5) and a second disconnection detector (9) provided in a wire rewinding part of an existing wire cut discharge machine. Between the pulleys (8) and the first and second variable resistors (4, 7) is provided, the resistance value of which changes in accordance with the pre-tension of the wire, the output of the first and second variable resistors (4, 7) By connecting to the one-chip microprocessor 14 which performs the overall control function of the electric discharge machine, the rotation speed of the speed motor 1 is automatically controlled to a value corresponding to the change value of the variable resistor, so that the pretension of the wire can be smoothly controlled. This can prevent wire breakage caused by electric discharge in advance, and improve the efficiency and reliability of wire processing.

Description

Wire Pretension Control of Wire Cut Discharge Machine

1 is a front view of the wire rewinding portion of the present invention.

2 is a front view of the wire feeding portion of the present invention.

3 is a cross-sectional view of the connection state of the pulley and the variable resistor for changing the up and down movement of the wire to the resistance value.

4 is a schematic block diagram of controlling a speed motor.

5 is a flowchart for explaining an operating state of the apparatus of the present invention.

6 is a device circuit diagram for driving a speed motor.

Explanation of symbols on the main parts of the drawings

1: speed motor 2,8: pulley

3,9: first and second open circuit detectors 4,7: first and second variable resistors

5: Recovery Bobbin 6: Breaker

10: supply bobbin 12: connecting shaft

3: weight 14: one-chip microprocessor

16: PLD 17: Motor Drive

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire free tension control device of a wire cut discharge machine, and more particularly, to an apparatus for controlling a recovery part wire pretension in order to limit a wire disconnection part to a machining part and to prevent sagging of the wire. .

In general, the wire cut electric discharge processing device controls the energy generated by the discharge to process the material. Since the diameter of the electrode for discharge uses a thin wire of about 0.005-0.3 mm, the wire tension is not controlled. In order to prevent frequent disconnection and deflection, an apparatus for limiting the disconnection portion of the wire and controlling the pretension on the wire is required.

The wire feeding device installed in the conventional wire discharge machine was configured such that the wire worn by the discharge was recovered by the roller and the rewinding recovery device located at the lower part of the machine.

Therefore, after being used, the wire is recovered to the recovery box or recovery bobbin by the lower roll and the recovery roll without adjusting the tension, wherein the recovered wire is driven by the rewinding motor driving the recovery roll and the speed motor driving the lower roll. It is transmitted along the recovery path with a constant tension.

However, such a conventional wire cut electrical discharge machining apparatus recovers the wire without giving any pretension to the recovery part, so that the wire worn by the discharge may cause disconnection, thereby reducing the efficiency and reliability of the machining operation. there was.

The present invention has been made to solve such a conventional problem, and by installing a variable resistor capable of controlling the speed of the rewinding motor in the wire recovery path, the wire is prevented from disconnection of the wire worn by the discharge in advance, An object of the present invention is to provide a wire pretension control device for a wire cut electric discharge machine capable of improving the efficiency and reliability of machining operations.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a front view of a wire rewinding unit for controlling pre-tension of a free wire according to the present invention, and the recovery bobbin 5 is accumulated on the upper left side of the rewinding body unit 100 of a predetermined width, The first variable resistor 4, the pulley 2, the speed motor 1 and the first disconnection detector 3 are arranged in a zigzag manner from the bottom to the top.

2 is a front view of the wire feeding unit, and a breaker 6 and a wire supply bobbin 10 are installed on the upper, left and right sides of the feeding body 200 having a predetermined width, and a second disconnection detector ( 9) is installed but the lower left, right has a configuration in which the variable resistor 7 and the pulley (8) is installed.

3 is a view illustrating a connection structure between the pulleys 2 and 8 and the first variable resistor 4 for converting the up and down motion of the wire into a resistance value in order to feed back the position of the variable resistor. The weight 13 installed on the connecting shaft 12 is installed to adjust the degree of pulley flow of the first variable resistor 4 generated by the deflection of the wire.

4 schematically shows a block for controlling the rewind speed motor 1, comprising: a comparator 21 for comparing a position change amount of a resistor with a reference value; And a current amplifier 22 which amplifies the command value x (t) output from the comparator 21 to an output value y (t) of a predetermined level and applies it to the speed motor 1.

FIG. 6 shows a device circuit for driving the rewind speed motor 1, which includes an analog channel 141 for receiving analog signals output from the first and second variable resistors 4 and 7; A one-chip microprocessor 14 having a standard port 142, a data bus 143, an address bus 144 and a pulse width modulation (PWM) generator 145; First and second disconnection detectors 3 and 9 having a photo coupler PC1 and a disconnection switch SW1; A PLD (16) for selectively outputting the pulse width modulated signal output from the one-chip microprocessor (14) through four photocouplers (PC2-PC5); The motor driving unit includes four transistors Q1-Q4, bias resistors R1-R4, and capacitors C1-C4 to control the driving direction of the speed motor 1 according to the signal output from the PLD 16. It consists of 17.

Referring to Figure 5 the effect of the present invention configured as described above is as follows.

First, when deflection of the wire occurs in the wire rewinding unit and the wire feeding unit shown in FIGS. 1 and 2, the axes of the first and second variable resistors 4 and 7 are used to determine the gravity of the weight 13. Receiving sags up or down, the change in resistance due to sagging of the wire is input to the analog channel 141 of the one-chip microprocessor 14 by the mechanical structure.

At this time, the one-chip microprocessor 14 first receives a reference value as shown in FIG. 5, and then detects whether or not a predetermined output signal is generated from the first and second disconnection detectors 3 and 9, if any. While maintaining the current motor driving state, when the disconnection detection signal is input, the driving of the speed motor 1 is stopped by blocking the execution of the control program.

However, if no output signal is generated from the first and second disconnection detectors 3 and 9, the resistance value fed back from the first and second variable resistors 4 and 7 is input as a sampling value of the digital signal. The reference value set in advance is compared with each other through the comparator 21.

That is, after detecting how much error has occurred in the reference value, the output signal of the pulse width modulation generator 145 is modulated with the error value amplified by the current amplifier 22.

The PWM pulse modulated as described above is input to the PLD 16 and converted into a signal for bridge driving the motor driver 17, and then transistors constituting the motor driver 17 through four photocouplers PC2-PC4 ( Since the transistors Q1-Q4 in the motor driver 17 are selectively turned on because they are respectively input to the bases of Q1-Q4, the driving speed of the speed motor 1 is automatically changed to a corresponding value.

At this time, the reference value compared with the resistance value fed back from the first and second variable resistors 4 and 7 fixes the pulleys 2 and 8 of the first and second variable resistors 4 and 7 at a certain position. Depending on whether it is enabled, it can have various values (e.g., termination, median, etc.).

In addition, in the present invention, the drive speed of the motor is automatically controlled by receiving feedback of the resistance value change of the first and second variable resistors 4 and 7 without receiving the speed value of the speed motor 1, and thus, the wire is discharged. Can be prevented from being worn out and disconnected.

On the other hand, in the above described an embodiment of detecting the position change amount due to the deflection of the wire through a variable resistor, the same effect can be obtained even if the drive speed of the speed motor is controlled by detecting the change amount of the wire through various other sensors, etc. have.

As described above, according to the present invention, by controlling the pre-tension of the wire by installing a variable resistor for position sensing in the wire recovery path of the wire cut electric discharge machine, the disconnection of the wire worn by the discharge can be prevented in advance. This can improve the efficiency and reliability of the wire processing operation.

Claims (1)

Breaker 6 and the wire supply bobbin 10 is installed on the upper left and right of the feeding body portion 200 of the predetermined width, and the wire feeding part provided with the variable resistor 7 and the pulley 8 on the lower left and right sides; ; A recovery bobbin 5 is disposed on the upper left side of the rewinding body part 100 having a predetermined width, and a wire rewinding part provided with a pulley 2, a first disconnection detector 3, and a speed motor 1 at the bottom thereof. In one wire cut electric discharge machine, between the pulley 2 and the recovery bobbin 5 provided on the upper part of the speed motor 1, and between the second disconnection detector 9 and the pulley 8 according to the pretension of the wire. One-chip microprocessor for installing the first and second variable resistors 4, 7 whose resistance values are changed, and the outputs of the first and second variable resistors 4, 7 perform the overall control function of the discharge processing machine. And (14), so that the rotation speed of the speed motor (1) is automatically controlled to a value corresponding to the difference between the reference value and the variable resistor.