JPS61121831A - Electric wire discharge machining unit - Google Patents

Abstract

PURPOSE:To make the tension of a wire electrode maintain constant for the purpose of improving the machining accuracy by decreasing the torque of a torque motor giving torque to a wire bobbin with decreasing of the diameter of the turn of the wire electrode of the wire bobbin. CONSTITUTION:As a wire electrode is delivered from a wire bobbin, the diameter of wire turn decreases. This decreasing amount is detected by a non-contact type and optical fiber type displacement sensor 13 and is entered in a control unit 14. The control unit 14 determines the torque of a torque motor 12 by the input signals of the displacement sensor 13 having been previously measured and stored as tension and the related table of input voltage of the torque motor 12 to so control the torque motor 12 as to decrease the torque. By this constitution, the total tension of the wire electrode can be maintained constant and the machining accuracy can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention places a wire electrode facing a workpiece at a minute interval, and generates a pulsed electric discharge between the workpiece and the wire electrode. The present invention relates to a wire electrical discharge machining apparatus that cuts a workpiece using electrical discharge energy, and is particularly designed to keep the tension of the wire electrode constant during cutting.

[Conventional technology]

Wire electric discharge machining devices are generally known as being capable of easily performing complex cutting operations on hard metals and the like with high precision.

This wire electrical discharge machining apparatus is provided with a tension mechanism that prevents the wire electrode from sagging and always applies a predetermined tension to the wire electrode necessary for wire electrical discharge machining.

Figure 5 shows the above-mentioned tension and
FIG. 3 is a configuration diagram of a Yon mechanism. In the figure, 1 is a wire bobbin, 2 is a pulley, 3 is a brake roller, 4 is a pulley, 5 is a brake presser, 6°7 is a pulley, 8 is a wire winding roller, 9 is a pinch roller, and 10 is a wire collection box. , 11
is a wire electrode, 12 is a torque motor, and the wire electrode 11 wound around the wire bobbin 1 is connected to the pulley 2, brake roller 3 and pulley 4, brake presser 5, and pulley 6.
．． 7, a wire winding roller 8, and a pinch solar 9 before reaching a wire collection box 10.

The wire electrode 11 wound around the wire bobbin 1 is sandwiched between the wire winding roller 8 and the pinch roller 9, which are rotating at a constant speed, and is unwound from the wire bobbin 1 at a constant speed. A predetermined tension is applied to this wire electrode 11 by the brake roller 6 . Also, in order to prevent the wire electrode 11 from coming off the wire bobbin 1, the torque motor 1 is
2, the wire bobbin 1 is biased to apply a constant torque in a direction opposite to the direction in which the wire electrode 11 is fed out. Therefore, the wire electrode 11 is fed out while being sandwiched between the wire winding 8 and the pinch roller 9, and the wire electrode 11 being sent out is braked by the brake roller 3 and the torque motor 12, thereby causing the wire electrode to A predetermined tension is generated in 11.

When the wire electrode 11 is consumed and reduced by the cutting process, and the winding diameter of the wire electrode 11 wound around the wire bobbin 1 becomes smaller, the torque applied by the torque motor 12 is constant, so the torque of the torque motor increases. The resulting tension in the wire electrode 11 increases, thus increasing the overall tension in the wire electrode.

[Problem that the invention seeks to solve]

In the conventional wire electric discharge machining apparatus as described above, there is a problem in that when the wire electrode is consumed and reduced by the cutting process, the overall tension of the wire electrode increases and the machining accuracy deteriorates.

This invention was made to solve this problem, and when the winding diameter of the wire electrode wound on the wire bobbin becomes small, a torque is applied that urges the wire bobbin in a direction opposite to the direction in which the wire electrode is supplied. It is an object of the present invention to provide a wire electrical discharge machining device in which the torque of a motor is reduced, thereby making the overall tension of the wire electrode constant, thereby making it possible to improve the accuracy of wire electrical discharge machining.

[Means for solving problems]

The wire electrical discharge machining apparatus according to the present invention provides, during cutting,
The wire electrode wound around the wire bobbin is pulled out at a predetermined speed using a pinch roller, etc., the wire bobbin is urged in the direction in which the wire electrode is supplied by a torque motor to apply tension to the wire electrode, and the wire electrode is wound around the wire bobbin using an optical sensor. The amount of decrease in the winding diameter of the rotated wire electrode is detected without contact with the wire bobbin, and the torque of the torque motor is decreased in accordance with the signal detected by the optical sensor.

[For production]

In this invention, a wire electrode wound around a wire bobbin is pulled out at a predetermined speed using a pinch solar or the like.
The torque motor urges the wire bobbin in the opposite direction to the direction in which the wire electrode is supplied, so tension is applied to the wire electrode, and an optical sensor detects the amount of decrease in the winding diameter of the wire electrode wound around the wire bobbin. The torque of the torque motor is reduced in response to the signal detected by the contact and detected by the optical sensor, thereby keeping the tension in the wire electrode constant.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention. In the figure, the reference numeral 1 indicates a wire bobbin around which a wire electrode is wound, and the reference numeral 12 indicates a torque motor, which are the same or corresponding parts to those with the same reference numerals in the conventional wire electric discharge machining apparatus explained in FIG. 5 above. It is something. 1
6 is an optical fiber-based displacement sensor that detects the amount of decrease in the winding diameter of the wire electrode wound around the wire bobbin 1 without contacting the wire bobbin 1, and 14 is a control device that controls the wire electric discharge machining. Figure 2 shows the optical fiber-based displacement sensor 13.
This shows the arrangement (random type) of fiber bundles for
The white circle indicates the receiving fiber, and the black circle indicates the input optical fiber. The output from the fiber optic displacement sensor 13 controls the torque of the torque motor 12 as shown in FIG.

In FIG. 3, reference numeral 12 denotes the above-described torque motor, 1
4 is a control device. Reference numeral 15 denotes a photoelectric converter, which converts the light intensity output signal inputted from the optical fiber displacement sensor 13 through the terminal 16 into an electric signal (voltage). Reference numeral 17 is a table, which is created by previously measuring the relationship between the output voltage of the photoelectric converter 15 and the input voltage of the torque motor 12 when the tension of the wire electrode is kept constant.

In the wire electrical discharge machining apparatus configured as described above, when cutting is started, a wire electrode is paid out from the wire bobbin 1 by a tension mechanism (not shown) similar to the conventional tension mechanism explained in FIG. 5 above. . To prevent the wire electrode from coming off the wire bobbin 1 while the wire electrode is being fed out, a predetermined torque is applied to the wire bobbin by the torque motor 12 in the opposite direction to the feeding direction of the wire electrode. . If the cutting process is continued in this state, the winding diameter of the wire electrode on the wire bobbin 1 will gradually decrease, and the torque motor 12
Since a constant torque is applied to the wire bobbin 1, the tension of the wire electrode gradually increases. The displacement when the winding diameter of the wire electrode on the wire bobbin 1 gradually decreases is detected by the optical fiber displacement sensor 16,
The detection results are supplied to the control device 14 described above.

FIG. 4 shows the light receiving characteristics of the optical fiber displacement sensor 13. In the range of displacements A and B, the received light intensity output of the optical fiber displacement sensor 13 increases as the winding diameter of the wire electrode decreases. This received light intensity output is input to the control bag 214, and the above-mentioned received light intensity output is converted into an amount of electricity (voltage) by the photoelectric converter 15 shown in FIG. Next, referring to Table 17 (this table shows the relationship between the output voltage of the photoelectric converter 15 and the input voltage of the torque motor 12 when the tension is constant), the output voltage of the photoelectric converter 15 is Find the input voltage to the torque motor 12 to keep the tension of the wire electrode constant corresponding to . Then, the input voltage of the torque motor 12 is output from the control device 14 to the torque motor 12 (in this case, the voltage is lowered) to lower the torque of the torque motor and keep the tension of the wire electrode constant.

〔Effect of the invention〕

As explained above, in this invention, the wire electrode 11 is opposed to the workpiece at a minute interval, and the workpiece is cut by pulsed discharge energy between the workpiece and the wire electrode 11. In wire electrical discharge machining equipment,
During the cutting process, the wire electrode 11 wound around the wire bobbin 1 is pulled out at a predetermined speed by means including a wire winding roller 8, a pinch roller 9, etc., and the wire bobbin 1 is moved in a direction opposite to the feeding direction of the wire electrode 11. A torque motor 12 that energizes and applies tension to the wire electrode 11; and an optical fiber-based displacement sensor 16 that detects the amount of decrease in the winding diameter of the wire i[11 wound around the wire bobbin 1 without contacting the wire bobbin 1. The torque of the torque motor 12 is reduced in accordance with the signal detected by the optical sensor, and the tension of the wire electrode 11 is kept constant. It is possible to prevent the accompanying change in the tension of the wire electrode 11, and there are effects such as enabling highly accurate electrical discharge machining.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention. FIG. 1 is a configuration diagram of the main parts of the tension mechanism, FIG. 2 is an il1 diagram of a fiber bundle for a displacement sensor using optical fibers, Figure 6 is a block diagram explaining the method of keeping the tension constant, Figure 4 is a light reception characteristic diagram of the displacement sensor using Optical 7 Eyepa,
FIG. 5 is a configuration diagram showing a tension mechanism in a conventional wire electric discharge machining device. 1: Wire bobbin, 11: Wire electrode, 12: Torque motor, 16: Displacement sensor using optical fiber Note that the same reference numerals in the drawings indicate the same or equivalent parts.

Claims (1)

[Claims] A wire electrical discharge machining device that places a wire electrode facing a workpiece at a minute interval, generates a pulsed electric discharge between the workpiece and the wire electrode, and cuts the workpiece using discharge energy. means for drawing out the wire electrode wound around the wire bobbin at a predetermined speed during the cutting process; and a torque motor for applying tension to the wire electrode by urging the wire bobbin in a direction opposite to the feeding direction of the wire electrode. and an optical sensor that detects a decrease in the winding diameter of the wire electrode wound around the wire bobbin without contacting the wire bobbin, and adjusts the torque of the torque motor according to the signal detected by the optical sensor. A wire electrical discharge machining apparatus characterized in that the tension of the wire electrode is kept constant.