JPH0643011B2 - Machining fluid circulation supply device of electric discharge machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a working fluid applied to an electric discharge machining apparatus, which is a homogeneous dispersion mixed solution in which the main composition components are oil, water and a surfactant, and the water content is 3 to 50. The present invention relates to a device for circulating and supplying a working fluid (%) to a working portion while always maintaining the required properties and composition.

As a usual working liquid suitable for conventional electric discharge machining, a liquid consisting of kerosene or a liquid obtained by uniformly dispersing and mixing oil, water and a surfactant is used. Many proposals have been made for the electric discharge machining liquid to increase the machining speed, improve the stability in machining, increase the efficiency of machining energy, and improve the machining accuracy. Among them, the oil sol composed of a mixed composition in which oil and water are uniformly dispersed has many advantages, has a small energy loss, has a good liquid wear ratio, is easily discharged, and is excellent in cooling property. Since the machining speed can be improved as a large current machining by high energy discharge and the dimensional accuracy of the product is good, it has been used as a machining fluid for high speed rough machining with improved productivity.

Further, it is known to apply a working fluid having a water content of 3 to 50% and the balance of oil and an additive. It was confirmed that a nonionic one suitable for obtaining a stable sol / colloid, etc., is suitable for this, that is, the emulsion additive is added and finely and uniformly dispersed to obtain a mixed state. Is used to maintain good performance.
However, there are many points to keep in mind. 50% moisture
If it becomes the above, electric leakage, the occurrence of arc discharge, and the difficulty of firework discharge between the electrodes are involved. When the water content is 3% or less, the electric conductivity in the liquid is reduced, the machining passage is not stable, and the risk of fire is increased. Therefore, within the range of 3 to 50% water, the water content is selected so that the water content is constant according to the requirements of the processing conditions, the purpose of the work, the processing speed, the processing dimension accuracy, the energy efficiency, and the like. It must be done to maintain the standard value. And this must be automatically and continuously controlled. Thus, good control of the machining fluid is one of the important factors in the electric discharge machining process.

Therefore, in the electric discharge machining with such oil / water mixed machining fluid, the water component in the machining fluid contributes to the easy discharge property, and the proportion of water droplets that are involved in the discharge path is increased. In many cases, the water component is easily decomposed and easily evaporated or low temperature evaporative with respect to the oil component, and the ratio of its decomposition (including electrolysis) and evaporation is large with respect to the oil component. Since the machining current for high-speed rough machining using an oil / water mixed machining fluid is usually several times greater than that for an oil / water mixture, the wear rate and amount of water components in the oil / water mixed machining fluid are It is a large value, and the change in the composition of such a working fluid occurs rapidly in time and at a large rate.

Therefore, in the processing using such oil / water mixed working fluid, if the working fluid temperature is kept almost constant by cooling control, etc., it is necessary to add and replenish the groove with a large amount of wear due to measurement detection, etc. Therefore, even if the method or apparatus for measuring the composition of the working fluid is a known method, the required oil content, water content, additive amount or a mixture thereof is added by detecting these and transmitting them to the overall control device, It is necessary to keep it constantly constant for good electric discharge machining.

It was confirmed that the water content is set to a predetermined value which is optimum for the intended processing within the range of 3 to 50%, and the set value is kept constant during the processing within an error of about ± 1 to 3%. As an example in FIG. 3, as shown in the absorption or attenuation characteristics of microwaves depending on the water component content of the working fluid, the "moisture-detection sensitivity relationship curve A" must be clearly known and the time required for adjustment is It was confirmed to be extremely quick.

Even at the initial stage of colloid production, ultrasonic vibration is applied to improve mixing, electrodes are jumped during electrical discharge machining, and liquid is agitated. When the types and proportions of the components of each composition are made constant, it is possible to form a certain electric discharge gap without causing the electric discharge machining portion to partially expand or narrow during electric discharge machining. This is particularly effective in designing and manufacturing a die. It is of primary importance to mix the working fluid to a composition that is optimal for processing from a number of other events, and in particular to maintain the proportion of oil water at a proper proportion. As the detection signal for keeping the required ratio of the oil-water mixture constant, as is clear from the curve A in FIG.
It is preferable to detect the amount of attenuation of microwave in the working fluid.

From the above point of view, the present invention maintains the mixing ratio of the oil-water mixed processing liquid containing water at a predetermined ratio within the range of 3 to 50% by weight, which is circulated and supplied to the processing unit, within the required allowable range. It is an object of the present invention to provide a machining liquid circulating and supplying device suitable for the purpose.

In order to achieve this object, the working fluid circulation supply device of the present invention includes a microwave attenuation amount detecting device for irradiating the working fluid with microwaves to measure the attenuation amount in the working fluid, in the working fluid circulation path. In addition to the above, a control device is provided which compares the detection value of the microwave attenuation amount detection device with a reference value and supplies water to the working fluid so that the detection value maintains a predetermined value.

Then, according to the present invention which adopts this configuration, a good working liquid for working is under control, a liquid state suitable for working work can be kept constant, a discharge gap is completely maintained, an arc is generated, The effects of eliminating electrical loss, improving machining characteristics, eliminating machining defects due to arc discharge, and further eliminating the risk of fire.

Next, the outline of the present invention will be described. FIG. 1 shows a schematic explanatory view of an embodiment of the present invention. The property of the liquid in the oil / water mixed liquid reservoir 20 supplied from the electric discharge machining unit (not shown) through the pipe 19 is a detection value measured by the specific gravity detection device 1, a detection value measured by the microwave attenuation amount detection device 2, and a sound velocity detection. The detection value of the sound velocity in the working fluid measured by the device 3, the detection value of the reflected light and the transmitted light of the light wave measured by the photodetector 4, and the detection value of the non-illustrated electric conductivity detection device. The detected value is sent to the overall control device 11 by the respective circuits 21, 22, 23, 24.
The control device 11 compares the detection signal of the microwave attenuation amount detection device 2 with the reference value, or compares the detection signal of another type with the reference value, and outputs the oil content according to the comparison result. The supply device 15 or the water supply device 16 is operated, and the liquid reservoir 20 is supplied through the respective pipes 12 or 13.
A required amount of oil or water is supplied to the oil / water mixing tank 10 communicating with the pipe 5 and a surfactant is added to uniformly mix the oil and water. The pump device 14 is actuated, and the mixed liquid uniformly dispersed in the mixing device 10 is actuated by the switching valve 6 to be sent to the electric discharge machining unit through the pipe 8 and the electromagnetic switching valve 9 and the pipe 19. In the mixing device 10, a liquid having a uniform composition at a required mixing ratio is supplied to the processing section at a required speed and in a required amount. In this way, the apparatus of the present invention can maintain uniform mixing with a constant water content and perform good electric discharge machining.

FIG. 2 is a partial cross-sectional front view of an embodiment of the present invention in which the microwave attenuation amount is measured for the working liquid in the working liquid tank 32. The electric discharge machine 30 is arranged on the foundation 38, and the work 39 is electric discharge machined in the liquid 33 in the machining liquid tank 32. The liquid 33 operates the screw 37 of the stirrer 27 to keep the mixing uniform.

The processing liquid for the processing liquid tank 32 is constantly measured by the microwave detection device 48, and the detection signal is transmitted to the control device 31 via the circuit 36. The control device 31 compares the reference value with a reference value to determine if the water content is insufficient. In this case, the water supply valve 29 is controlled to supply the required amount of water supplied from the water supply pipe 34 to the tank 32 via the pipes 28 and 26.

The liquid 33 constantly measures the required properties, has the required properties and the required composition, and maintains a constant moisture ratio arbitrarily selected from the range of 3 to 50% moisture. The detection sensitivity by microwaves changes with respect to water (horizontal axis) as shown in FIG. The irradiation microwave was measured at 1.1 GHz for a surface active agent + water + oil processing liquid, and by controlling the water content with this detection signal, the water content can be controlled within a constant range of ± 1%.

In the embodiment shown in FIG. 1, a specific gravity detection device 1 for measuring various properties of the working liquid in the liquid tank 20, a microwave attenuation amount detection device 2,
Specific examples of the sound velocity detecting device 3 and the light detecting device 4 are briefly shown in FIGS. 4A, 4B, 4C, and 4D.

FIG. 4A is a partial cross-sectional front view of an embodiment in which the liquid specific gravity detection device performs detection control in the liquid reservoir 20 provided in a part of the machining liquid circulation path. A hydrometer 5 is added to the machining liquid 33 in the liquid tank 20.
A device 53 for arranging 2 and converting a floating height change into an electrode field change and measuring controls the control valve by a detection signal so that the specific gravity of the working fluid corresponds to the set standard value according to the detected specific gravity change. Control mixing of water.

FIG. 4B shows a detection device 56 for generating a microwave.
The intensity of the microwave (the amount of attenuation) of the emitted microwave that propagates through the liquid 33 and is reflected by the bottom surface of the tank 20
Thus, the amount of absorption by the liquid 33 is known, and the property of the liquid is detected. FIG. 4C shows that the ultrasonic wave is transmitted from the transmitter 56 and the receiver 58 is used by using the detecting device 57 based on the speed of sound of the working fluid.
Is received, and the received signal is transmitted to the device 57 via the circuit 59 to measure the time for passing through the liquid. The speed of sound becomes slower as the oil content increases. When the increase in oil content is detected, the water content increases. FIG. 4D is an optical detection device. The light generated by the laser generator 62 is reflected by the reflection plates 64 and 65 into the liquid 33, and further reflected by the vertical reflection plate 66 provided with a predetermined interval length of the liquid, transmitted through the reflection plate 65 or at a predetermined angle. A photo-detecting device 6 that reflects and is closely provided on the reflecting side wall
Light is received at 3. The water content can be measured by utilizing the phenomenon that the light reflectance and the light transmittance change as the oil-water mixture composition changes. Known methods and devices may be used for these measurement and detection methods.

FIG. 5 is an enlarged partial sectional front view of a machining portion in the electric discharge machining tank. The electric discharge machine 30 is arranged on the foundation 38 and the work electrode 39 is opposed to the machining electrode 42 attached to the tip of the drive shaft 45 which is moved in the axial direction by the drive device 46, and the machining tank 33 is filled with the machining liquid 33 for electric discharge machining. However, in order to improve cooling, the tank wall of the liquid tank 32 is bellowed, and the liquid tank 3
2 is provided with a tank 44, cooled by a liquid (mainly water) 40, the working liquid 33 is supplied to a working portion from a liquid feed pipe 34 provided at the upper part, and discharged from an outlet 41, and the liquid temperature is controlled. It is the one to put. The properties of the working liquid 33 are measured and changes are detected to obtain the required uniform mixed composition, and the state thereof is always detected and maintained constant. Reference numeral 43 is a pad member that adheres the liquid tank 32 to the workpiece 39 to prevent the processing liquid 33 from leaking.

As described above, according to the present invention, as is clear from the relationship curve A between the water content% and the detection sensitivity db shown in FIG. 3, by measuring the microwave attenuation, the water content ratio in the working fluid can be accurately determined. It is possible to quickly adjust and maintain the water content ratio within the error range of about ± 1% to the predetermined value set within the range of 3 to 50% by detecting the water content ratio. It is possible to perform stable and highly accurate processing without lowering the accuracy or the processing efficiency.

Further, the present invention detects the water content ratio in the working fluid by measuring the amount of microwave attenuation,
In addition to the microwave attenuation measurement, as described above, the specific gravity,
It is also possible to combine measurements of sound velocity, light reflectance and transmittance.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an embodiment of the present invention, FIG. 2 is a partial sectional front view of an embodiment of the present invention, FIG. 3 is a relationship diagram of moisture and detection sensitivity, and FIG. 4A is a specific gravity detection device. Partial sectional front view of
FIG. 4B is a partial cross-sectional front view of the microwave attenuation amount detecting device, FIG. 4C is a front view of the detecting device by sound velocity, FIG. 4D is a light detecting device, and FIG. 5 is a partial cross-sectional view of another application example. It is a front view. 1 ... Specific gravity detection device 2 ... Microwave attenuation amount detection device 3 ... Sonic velocity detection device 4 ... Photodetection device 10 ... Mixing tank 11 ... Control device 14 ... Pump device 30 ... Electric discharge machine 33 ... … Processing liquid 20.32 …… Liquid tank

Claims (1)

[Claims] 1. A processing liquid, which is obtained by uniformly dispersing and mixing oil and water in a predetermined ratio within a range of 3 to 50% by weight, is circulated and supplied to a processing portion where an electrode and a workpiece face each other. In the machining fluid circulating and supplying device of the electric discharge machine, which performs the microwave irradiation, the microwave is applied to the machining fluid to measure the attenuation in the machining fluid. Of the electric discharge machine, wherein a control device is provided for comparing the detection value of the microwave attenuation amount detection device with a reference value and adding water to the machining fluid so that the detection value maintains a predetermined value. Machining liquid circulation supply device.