JP3034982B2 - Machining fluid control device for electric discharge machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a machining fluid control device for an electric discharge machine which performs an electric discharge machining in a machining fluid and controls an injection amount and a discharge amount of the machining fluid.

[0002]

2. Description of the Related Art In a die-sinking electric discharge machine, an immersion type wire electric discharge machine and the like, a machining fluid is put into a machining tank, and electric discharge machining is performed in the machining fluid. During electric discharge machining, machining waste (sludge) removed from the workpiece is diffused into the machining fluid. When there is much sludge in the processing fluid (when the sludge concentration is high)
Since a short circuit or abnormal arc discharge occurs in the discharge gap, it is necessary to replenish the machining fluid to prevent the sludge concentration from increasing. Such a working fluid exchange device will be described with reference to the drawings. FIG. 6 is a system diagram of a conventional machining fluid replacement device. In the figure, 1 is a processing tank, 1a is an adjustment partition for adjusting the liquid level of the processing liquid provided in the processing tank 1,
Reference numeral 2a denotes a dirty tank from which the processing liquid is discharged from the processing tank 1, and 2b denotes a clean tank for storing a clean processing liquid obtained by removing sludge from the processing liquid in the dirty tank 2a. Reference numeral 3 denotes a pump driven by the motor 3M, which transfers the working fluid in the dirty tank 2a through the filter F into the clean tank 2b. Sludge is removed by the filter F, and a working fluid free of sludge is stored in the clean tank 2b. Reference numeral 4 denotes a pump driven by a motor 4M, which pumps up the processing fluid in the clean tank 2b through the filter F and pumps the processing fluid into the processing tank 1.
Pour into the bottom of 4V is a flow control valve interposed in the injection path from the pump 4M. Reference numeral 5 denotes a pump driven by a motor 5M, which sucks up the working fluid in the clean tank 2b through a filter F and supplies it to a machining gap in electric discharge machining. 5V is a flow control valve interposed in the injection path from the pump 5M. Reference numeral 6 denotes a cooler for controlling the temperature of the working fluid. During the electric discharge machining, the machining fluid is injected from the clean tank 2b into the machining tank 1, and the excess machining fluid in the machining tank 1 overflows from the upper part of the adjustment partition 1a and is collected in the dirty tank 2a. In addition, the machining fluid from the pump 5 is supplied to the discharge gap to quickly discharge sludge between the gaps. The amount of the processing liquid from the clean tank 2b to the processing tank 1 is adjusted by the flow control valves 4V and 5V. Thereby, the working fluid is circulated and the working fluid in the working tank 1 is always kept at a low sludge concentration.

[0003]

By the way, the sludge concentration in the processing tank 1 is determined by the flow rate of the processing liquid injected from the clean tank 2a into the processing tank 1 determined by the flow control valves 4V and 5V, and It is determined by the state of processing energy which affects the amount of sludge discharged to the furnace.
Therefore, after the machining energy is determined, the flow control valves 4V and 5V are manually adjusted accordingly, and electric discharge machining is performed in this state. However, the machining energy is not always constant during the electric discharge machining, and often changes with the progress of the electric discharge machining, and accordingly, the discharge amount of sludge per unit time often changes. For this reason, it has been difficult to maintain the sludge concentration in the processing tank 1 at an appropriate value from the start of processing to the end of processing.
An object of the present invention is to solve the above problems in the prior art,
An object of the present invention is to provide a machining fluid control device for an electric discharge machine capable of automatically maintaining a sludge concentration at an appropriate value.

[0004]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a first tank for storing a machining fluid and performing an electric discharge machining in the machining fluid, and a second tank for storing the machining fluid.
Tank, an injection path for injecting the processing liquid from the second tank to the first tank, and a discharge path for discharging the processing liquid from the first tank to the second tank. In the electric discharge machine, a detector for detecting a sludge concentration in the machining fluid in the first tank, a setting unit for setting an allowable value of the sludge concentration, and the allowable unit based on a machining amount of the electric discharge machining A correction unit that corrects a value, a flow adjustment servo valve interposed in the injection path, and a difference between an output value of the setting unit corrected by an output value of the correction unit and a detection value of the detector. An arithmetic unit and a control unit for controlling the flow regulating servo valve based on the value obtained by the arithmetic unit are provided. Further, the present invention provides a first tank for storing a machining fluid and performing an electric discharge machining in the machining fluid, a second tank for storing the machining fluid, and a first tank from the second tank. An injection path for injecting the working fluid into the second tank from the first tank;
And a discharge path for discharging the working fluid to the tank, wherein a number of flow paths are formed on the entire surface, and one is fixed in the first tank and the other is opposed to this. And a discharge device for adjusting a discharge amount of the processing liquid in the first tank to the discharge path. The present invention also provides a machining fluid control device for an electric discharge machine equipped with the above-mentioned discharge device, wherein the injection flow rate detector interposed in the injection path, the discharge flow rate detector interposed in the discharge path, A calculating unit for calculating a difference between the flow rate detector and the discharge flow rate detector; and a control unit for driving a movable-side plate of the discharging device based on a value obtained by the calculating unit. Features.

[0005]

According to the first aspect of the present invention,
The sludge concentration detected by the detector and the sludge concentration set in the setting section are compared while correcting the latter with a value based on the actual processing amount at that time, and the difference between the two is calculated, and the flow rate is calculated based on the difference. Adjust the opening of the adjusting servo valve. Thereby, the sludge concentration in the first tank is set to an appropriate value. In the second aspect of the present invention, of the two plate members, by moving the movable plate member, the overlapping area of a large number of flow passages of both plate members changes, and The size can be changed arbitrarily. Thereby, the first
The working fluid in the tank can be discharged from a number of locations in an arbitrary amount. Of the above inventions, the last one described in the above 2
In the invention described in the second aspect, the movable-side plate is driven based on a difference between the injection flow rate and the discharge flow rate, and the processing liquid amount in the first tank is automatically maintained at an arbitrary value.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a system diagram of a machining fluid control device of an electric discharge machine according to an embodiment of the present invention. In the figure, the same or equivalent parts as those shown in FIG.
Reference numeral 1b denotes a machining fluid discharge device for adjusting the discharge of the machining fluid from the machining tank 1, and 1bM denotes a motor for driving the machining fluid discharge device 1b. 7D is a sludge concentration detector for detecting the sludge concentration in the processing tank 1, and outputs an electric signal proportional to the detected sludge concentration. The sludge concentration detector 7D includes a light-emitting source and a light-receiving light source provided at a position facing the light-emitting source, and has a configuration for detecting the light transmittance of the processing fluid or a configuration for detecting the specific gravity of the processing fluid. Used. Reference numeral 8D denotes a discharge flow rate detector provided in a discharge path between the processing tank 1 and the dirty tank 2a to detect a discharge amount of the processing liquid discharged, and outputs an electric signal proportional to the detected flow rate. Reference numeral 40D denotes a circulating flow rate detector for detecting the flow rate of the working fluid flowing from the clean tank 2b to the bottom of the processing tank 1, and outputs an electric signal proportional to the detected flow rate. Reference numeral 50D denotes a supply flow rate detector for detecting a supply amount of the processing liquid supplied from the clean tank 2b to the processing gap of the processing tank 1, and outputs an electric signal proportional to the detected flow rate.

FIG. 2 is a block diagram of an injection flow rate control device for controlling the injection flow rate into the processing tank 1. In the figure, 7D is the same sludge concentration detector as that shown in FIG. 1, 10 is a sludge concentration setting unit, and 11 is an actual machining amount correction unit. An allowable value of the sludge concentration in the processing tank 1 is set in the sludge concentration setting unit 10, and an electric signal proportional to the value is output. The actual machining amount correction unit 11 inputs the machining removal amount obtained from the machining speed and the machining average current in the NC device that controls the electric discharge machining, and outputs a predetermined numerical value corresponding thereto as an electric signal. Reference numeral 12 denotes a sludge concentration detector 7D, a sludge concentration setting unit 10, and an actual machining amount correction unit 1.
An adder 13 adds the output value of 1 by adding the symbols (+,-) in the drawing, and 13 controls one or both of the motors 40M and 50M of the flow rate adjusting servo valves 40 and 50 based on the output of the adder 12. This is a drive device for controlling the flow rate of the servo valve.

Here, the operation of controlling the flow rate of the injection into the processing tank 1 will be described. The output of the sludge density setting unit 10 and the output of the actual machining amount correction unit 11 have the same sign (+) and have the same sign (+).
Is input to This is substantially the same as correcting the value of the sludge density setting unit 10 with the value output from the actual processing amount correction unit 11. That is, the set value increases as the processing removal amount increases, and the setting value decreases as the processing removal amount decreases. The adder 12 calculates the difference between the corrected set value and the value detected by the sludge concentration detector 7D, and outputs the result to the flow rate adjusting servo valve driving device 13. When the input value is a negative value, that is, when the sludge concentration is larger than the corrected set value, the flow adjustment servo valve driving device 13 drives one or both of the motors 40M and 50M to open the valve opening degree. And clean tank 2
The injection amount of the processing liquid b is increased, and the sludge concentration in the processing tank 1 is reduced. When the output value of the adder 12 is 0 or positive,
That is, when the sludge concentration of the processing tank 1 is equal to or less than the corrected set value, the flow rate adjusting servo valve driving device 13 sets the valve opening to 0 to close the injection passage. Thus, the sludge concentration in the machining tank 1 is automatically maintained at an appropriate value even when the state of the electric discharge machining energy changes. The adder 12
It is clear that the sign of the value input to the can be reversed.

The control of the working fluid injection has been described above. Next, control of processing fluid discharge will be described. FIG. 3 is a front view of the machining fluid discharge device 1b shown in FIG. 1, and FIG. 4 is a sectional view taken along line IV-IV in FIG. In each figure, 1b is FIG.
This is the same machining fluid discharge device as that shown in FIG. Processing liquid discharge device 1b, fixing plate 1b ₁₀ and the movable plate 1 of substantially the same shape
with a b _20. The fixed plate 1b ₁₀ has three through-holes h ₁₁ of the same size at the top is, three through-holes h ₁₂ of the same size in the middle is, three through-holes h ₁₃ of the same size in the lower formation Have been. The largest through-hole h _11, the smallest through-hole h _13. It is formed h ₁₄ notches in the bottom of the fixed plate 1b _10. On the other hand, the fixing plate 1b ₂₀ has three through-holes h ₂₁ of the same size at the top is, three through-holes h ₂₂ of the same size in the middle is a three same size of the lower through-holes h ₂₃ Are formed. Holes h ₂₁ is a through-hole h _11, the through-holes h
₂₂ is a through hole h _12, also through hole h ₂₃ is a through-hole h _13, are formed in each of the same size. d is the fixed plate 1b ₁₀
And a shift amount of the movable plate 1b _20, when the displacement d is 0, i.e., the through-holes in a state in which the upper and lower ends of the two plates are matched flow passage of the working fluid is closed by another plate body Disappears. On the other hand, when the displacement d increases, the fixed plate 1
the overlapping area of the through-hole cross each corresponding b ₁₀ and the movable plate 1b _20, i.e. flow passage is increased, also increases emissions of machining fluid. Further, notches h ₁₄ bottom of the fixing plate 1b ₁₀ also Yuku is opened in proportion to the deviation amount d increases. The overlapping area of the through holes h ₁₁ and h ₂₁ is A ₁₀ , and the through holes h ₁₂ and h ₂₁
In the area of overlap A ₂₀ of h _22, the area of overlap of the through-holes h _13, h ₂₃ are respectively represented by A _30. The shape of the through holes, the area A ₁₀ is the maximum, the area A ₃₀ is smallest is clear. In FIG. 4, reference numeral 1c denotes a support integrated with or fixed to the processing tank 1, and 1bM denotes a motor fixed to the support 1c. 1s is a feed screw which is rotated by the motor 1bm, 1n is a nut screwed with the feed screw 1s are fixed to the movable plate 1b _20. Screw 1s rotates the feed by driving the motor 1bm, and the movable plate 1b ₂₀ is displaced in the vertical direction can be obtained any deviation amount d, thereby, be arbitrarily determined emissions machining fluid it can. By being provided with notches h ₁₄ at the bottom, working fluid emissions therefrom is larger than the emission layer each stage, the effect of the discharge of sludge deposited on the bottom of the processing tank 1 Can be done Further, since the through holes are arranged in a stepped manner and the area is reduced in order from the upper stage, the discharge amount of the processing liquid is almost the same for each of the through holes, and smooth discharge can be performed. In addition, the size of each through hole, the number of stages, the number arranged in one stage, the arrangement state, and the like can be arbitrarily determined. The shape of the fixing plate 1b ₁₀ and the movable plate 1b ₂₀ is a clear need not coincide.

FIG. 5 is a block diagram of a drive control device for the motor 1bM shown in FIG. Reference numerals 8D, 40D, and 50D are the same discharge flow detector, circulating flow detector, and supply flow detector as those shown in FIG. Reference numeral 14 denotes an adder, and reference numeral 15 denotes a movable plate motor driving device that drives the motor 1bM based on the operation value of the adder 14. The flow rate detected by the circulating flow rate detector 40D and the flow rate detected by the supply flow rate detector 50D are added to be the total amount injected into the processing tank 1. If the total injection amount is larger than the value detected by the discharge flow detector 8D, the adder 14 outputs a signal indicating the difference between the two. Movable plate motor drive unit 15 drives the motor 1bM in response to this signal, to displace the movable plate 1b _20, to discharge the working fluid of the machining tank 1. If the two coincide, the output from the adder 14 becomes 0, whereby the movable plate motor driving device 15 returns the movable plate 1b ₂₀ to the original position, and closes the working fluid discharge device 1b. The drive control device automatically discharges the machining fluid, and can prevent an excessive or insufficient injection amount from occurring during the electric discharge machining, thereby preventing troubles in the machining. Naturally, a means for preventing the hunting by providing a dead zone in the movable plate motor driving device 15 is employed.

[0011]

As described above, in the present invention, the sludge concentration set value is corrected by the actual machining amount, and the opening of the flow rate adjusting servo valve is controlled by the difference between the sludge concentration and the detected sludge concentration. Therefore, the sludge concentration in the processing tank can be maintained at an appropriate value. Further, since the machining fluid discharge device is constituted by two plates having a large number of flow passages and one of the plates is movable to adjust the overlap of the flow passages, the discharge amount of the machining fluid is arbitrarily adjusted. Thus, the sludge concentration can be adjusted to an appropriate value. Further, since the driving of the one plate is controlled by the difference between the injection amount and the discharge amount, it is possible to automatically prevent the excess and deficiency of the machining liquid during the machining.

[Brief description of the drawings]

FIG. 1 is a system diagram of a machining fluid control device of an electric discharge machine according to an embodiment of the present invention.

FIG. 2 is a block diagram of a working fluid injection amount control device.

FIG. 3 is a front view of the working fluid discharge device shown in FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV shown in FIG. 3;

FIG. 5 is a block diagram of a control device of the working fluid discharge device.

FIG. 6 is a system diagram of a conventional machining fluid replacement device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing tank 1b Processing fluid discharge device 2b Clean tank 7D Sludge concentration detector 8D Discharge flow rate detector 10 Sludge concentration setting unit 11 Actual processing amount correction unit 12 Adder 13 Flow rate adjustment servo valve drive unit 14 Adder 15 Movable plate motor drive Device 40 Flow control servo valve 40D Circulating flow detector 50 Flow control servo valve 50D Supply flow detector

Claims (7)

(57) [Claims] 1. A first tank for containing a machining fluid and performing an electric discharge machining in the machining fluid, and a second tank for storing the machining fluid.
Tank, an injection path for injecting the processing liquid from the second tank to the first tank, and a discharge path for discharging the processing liquid from the first tank to the second tank. In the electric discharge machine, a detector for detecting a sludge concentration in the working fluid in the first tank , a setting unit for setting an allowable value of the sludge concentration, and the allowable value based on a machining amount of the electric discharge machining And a flow rate adjusting servo valve interposed in the injection path, and a calculation for calculating a difference between the output value of the setting unit corrected by the output value of the correction unit and the detection value of the detector. means and, working fluid control system for an electric discharge machine characterized by comprising a control unit for controlling the flow rate adjusting servo valve based on a value obtained by the calculation means. 2. The machining fluid control device for an electric discharge machine according to claim 1, wherein the injection passage is a passage for injecting a machining fluid into a machining gap of the electric discharge machining. 3. The machining fluid control device for an electric discharge machine according to claim 1, wherein the detector has a configuration for detecting a light transmittance of the machining fluid. 4. The machining fluid control device for an electric discharge machine according to claim 1, wherein the machining amount of the electric discharge machining is a machining removal amount obtained from an actual machining feed speed and an actual machining average current. 5. A first tank for containing a machining fluid and performing an electric discharge machining in the machining fluid, and a second tank for storing the machining fluid.
Tank, an injection path for injecting the processing liquid from the second tank to the first tank, and a discharge path for discharging the processing liquid from the first tank to the second tank. In the electric discharge machine, a number of flow passages are formed on the entire surface, one of which is fixed in the first tank and the other is made of two plate bodies which are movable in opposition to the first tank. A discharge device for adjusting a discharge amount of the processing liquid in the tank to the discharge path. 6. The discharge passage according to claim 5 , wherein the flow passages of the two plates of the discharge device are large at the bottom, and are formed sequentially from the bottom to the top at portions other than the bottom. Fluid control device for electric discharge machine. 7. The machining fluid control device for an electric discharge machine according to claim 5 , wherein an injection flow rate detector interposed in the injection path, a discharge flow rate detector interposed in the discharge path, and the injection flow rate detection. wherein a calculating means for calculating a difference between vessel and said outlet flow detector, and a control unit for driving the movable side of the plate body of the discharge device on the basis of the value obtained by the arithmetic means, that the provided Fluid control device for electric discharge machine.