JPS63156620A - Wire-cut electric discharge machine - Google Patents

Abstract

PURPOSE:To speed up preventive control over concentrated discharge, by installing a detection device, measuring temperature of an electrode, in the part run past a machining part to be opposed to a workpiece of the wire electrode, comparing the detection signal with the reference value set by working conditions, and installing a judging device for judging a degree of concentration of discharge. CONSTITUTION:A temperature rise in a wire electrode 1 can be detected and measured with noncontact by detection (by means of an infrared sensor 10) of an electromagnetic wave, making infrared rays to be emitted out of the electrode 1 a main factor, or through a measuring medium by direct contact. This detection signal is compared with the reference value inputted and set by working conditions, whereby concentrated discharge is judged by a judging device 12. Therefore, the temperature rise due to generation of this concentration discharge is accurately judgeable. According to this judgment, when the concentration discharge is generated, control of a working pulse, control over travel of the electrode 1, control of a jet working fluid, etc., are speedily performed whereby disconnection of the wire electrode 1 is prevented from occurring and thus stable machining can be done.

Description

DETAILED DESCRIPTION OF THE INVENTION [Applications of the Invention] The present invention relates to a wire-cut electrical discharge machining apparatus that cuts a workpiece into a desired shape by electric discharge machining using a wire electrode.

[Prior art and problems]

The thin electrode wire used in wide V-cut electric discharge machining has a thin wire diameter of 0.03 to 0.3 mmφ, and is likely to vibrate or bend during machining. Therefore, concentrated discharge is likely to occur, and wire breakage is easily caused by concentrated discharge, resulting in a disadvantage of lowering machining performance and machining accuracy.

(Means for solving the problem) The present invention is capable of detecting such concentrated discharge and quickly implementing preventive measures C11. A detection device is installed to measure the temperature of the electrode once ('1,
The present invention is characterized in that a determination device N is provided which compares the detection signal of the device with a standard value J, which is set according to machining conditions, to determine the degree of concentration of electric discharge.

〔Example〕

The present invention will be explained below with reference to an embodiment of the drawings. In Fig. 1, numeral 1 is a wire electrode, which is continuously fed out from a reel (not shown), runs on upper and lower guides 2, and moves as shown by the arrow. Will be taken over. A required tension and moving speed are applied to this 7-way pulling electrode 1 by a brake and a pulling device (not shown), and the workpiece 3 is processed by facing the electrode 1 which moves in a straight line through two guides. do. 4 is a nozzle that supplies machining fluid (ion exchange treated water) to the workpiece 3.
A machining pulse power source (not shown) is connected to a machining pulse power supply (not shown) through electrical currents provided above and below the wire electrode 1 in the guide, and a pulse discharge is generated between the electrode 1 and the workpiece 3 to perform machining.

FIG. 2 is a specific example of the temperature detection device 6 of the wire electrode 1 provided at the part of the wire electrode 1 in FIG. A reflection ii7 is provided on the Pb
It is detected by an infrared sensor 10 such as S. 9 is a filter, 1
1 is a detection signal amplifier, 12 is a discrimination device, and setting device 13
A temperature rise due to discharge concentration is determined by comparing with a reference value according to machining conditions and the like.

When performing electrical discharge machining by pulsed discharge between the wire electrode 1 moving the guide 2 and the workpiece 3, the wire A7 electrode 1
The discharge point of is heated by discharge heat. When the discharge point moves and electric discharge is generated in each part of the wire electrode 1 and stable machining is performed, the temperature of the wire electrode part that moves and passes through the machining part facing the workpiece 3 increases. is not that high. However, the bending of the wire electrode 1,
When a concentrated discharge occurs at a portion of the wire electrode 1 due to vibrations, machining debris, etc., the temperature of the wire electrode 1 suddenly rises, and the temperature rise at that portion radiates infrared rays to the surroundings. Therefore, the infrared rays emitted from the wire A7 electrode 1 that has moved through the processed part are collected by the reflecting mirror 1, focused by the lens 8, and detected by the infrared sensor 10 at the focal point (A). The detection signal of the sensor 10 increases in proportion to the upper limit of the temperature of the wire electrode 1, and when a concentrated discharge occurs, the sensor detection signal increases. The detection signal is amplified by an intermediate amplifier 11 and input to a discrimination device 12 . A reference value according to the processing conditions is inputted to the discrimination device 12 by the device 13, and when processed tea fl increases processing energy, the reference value is increased, and when processing energy is decreased, the base * value is decreased. Enter the settings as shown below. The determination device 12 compares this reference value with the detection signal from the sensor 10 to make a determination.

For example, if the comparative voltage difference is small, it is determined that the temperature upper limit of the wire electrode 1 is low and normal discharge is occurring, and if the differential voltage is large, it is determined that the temperature rise of the positive electrode is high and concentrated discharge is occurring. Of course, multiple stepwise determinations can be made, and the state of transition from stable discharge to abnormal discharge, etc. can be easily determined.

For example, when processing SK D material at a processing speed of 100 mm2/min using a 3s electrode with a wire diameter of 0.2 to 0.31111Iφ, the wire t moves the pole at a speed of 5 m/1n and moves through the processing section. When a control circuit is installed that detects the temperature of the wire electrode closest to the wire electrode with the I]bS sensor, discriminates the detection signal, and cuts off the machining pulse when a concentrated arc discharge is likely to occur. We were able to sufficiently detect and control the time from the occurrence of wire breakage to wire breakage, and were able to perform stable machining without any bullet damage.

Note that various highly sensitive infrared sensors can be used to detect electromagnetic waves such as infrared r;A emitted from a discharge-heated wire electrode. In addition, by passing a medium such as water through the discharge-heated soil electrode, the medium is rapidly heated to generate a cold sifter gas, steam, etc. at a temperature of approximately 80 to 100° C. at the center of the wire. Therefore, since this changes the light absorption in water, for example, using a Qa△S-''r force body, the underwater infrared rays are irradiated and the transmitted waves are detected and determined. Since the temperature is different, it is possible to easily know the temperature rise of the passing wire electrode, and it is possible to judge the state of stable machining discharge and concentrated arc discharge.And by being able to obtain the temperature hi side without contact in this way, Measurements can be made without disturbing the running state of the wire electrode, and temperature can be easily measured despite the high speed movement of the Wire A7 electrode, and highly reliable measurements can be obtained. It is also possible to use contact detection using a thermocouple, thermistor, etc., and it is also possible to measure the temperature via a heat medium such as a liquid or a solid.

The control of the wire cut 1-processing equipment based on the determination of concentrated discharge based on the temperature measurement of the life 1' life electrode described above is not limited to power interruption control, but also control of the extension of the pause width of the processing pulse, discharge current wave control, etc. 3. It is possible to control the reduction of candy, control the moving speed and tension of the wire electrode, control the jet pressure of the machining fluid supplied from the nozzle, and perform a combination of these a'IIIIl.

〔Effect of the invention〕

As described above, in the present invention, a detection device for measuring the temperature of the electrode is installed at the part of the wire electrode that passes through the processing portion facing the workpiece, and the detection signal of the device is set according to the regulation. Since it is equipped with a device that determines the concentration of discharge by comparing it with a reference value, the upper temperature limit of the life electrode can be detected non-contact or by detecting electromagnetic waves mainly infrared rays emitted from the electrode. It can be easily detected and measured by direct contact measurement or measurement through a medium, and highly reliable detection can be performed. Therefore, this detection signal is input to the reference value set according to the machining conditions.In other words, if the machining condition is set to high-energy roughing conditions, the reference value is increased, and if the machining condition is set to low-energy finishing condition, the reference value is lowered. Since the setting is set as follows, and concentrated discharge is determined by comparing the detection signal with this reference value, stable electrical discharge machining will cause the Wire A7 electrode to rise in temperature? It is possible to accurately determine the case where the temperature suddenly rises to a high temperature due to the occurrence of concentrated arc discharge, as distinguished from the case where the temperature rises to a high temperature of 17 J. If concentrated discharge occurs as a result of this judgment, stable IL machining can be performed to prevent wire A7 electrode breakage by quickly controlling the machining pulse, controlling the movement of the wife electrode, controlling the jet machining fluid, etc. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is an enlarged detailed view of a part thereof. 1...Wire electrode 2...Guide 3...Workpiece 4...Nozzle 5... ......Electronic transmission 6...Detection device 7...Reflector 8...Lens 10...・・・・Infrared sensor 12・・・・・・・Determination i Patent application Person: Kiyoshi Inoue 71, Representative of Inoue Japax Laboratory Co., Ltd. Figure 2

Claims (1)

[Claims] In a wire-cut electric discharge machining device that performs pulse discharge in the opposing gap between a wire electrode and a workpiece in which a guide plate is moved with a predetermined tension and speed, the machining portion of the wire electrode that faces the workpiece is A detection device for measuring the temperature of the electrode is provided at the portion through which the electrode passes, and a determination device is provided for comparing the detection signal of the device with a reference value set according to processing conditions to determine the degree of concentration of electric discharge. Wire cut electrical discharge machining equipment.