JPS62203725A - Supply device for electric machining fluid - Google Patents

Abstract

PURPOSE:To promptly and properly supply optimum machining fluid in accordance with a change of a machining condition, by supplying the machining fluid in a predetermined pressure and flow to an electric discharge machine from plural storage tanks storing the machining fluid having predetermined specific resistance, viscosity and fluid temperature. CONSTITUTION:A device contains machining fluid of low specific resistance in a machining fluid storage tank 1 while machining fluid of high specific resistance in a machining fluid storage tank 2. When rough machining is performed in an electric machine 34, a control unit 33, on the basis of a signal (a) from an NC unit 35, actuates a motor 7 driving a supply machining fluid pump 5 while instructs a reference value of flow to be controlled to a control flow meter 9 by a signal (g). Then the machining fluid in the storage tank 1 is fed to the machine 34 by the pump 5. Here a flow of the fluid is detected by the control flow meter 9, and the device, feeding a control signal to a flow control valve 11, holds a supply quantity of the fluid to a predetermined value. While during machining, if a programmed signal is successively output to the NC unit 35, the control unit 33, which outputs a control signal in accordance with the programmed signal, controls a flow control value to be changed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to electric processing machines, such as electrical discharge machines, wire-cut electrical discharge machines, electrolytic processing machines, etc., or processing machines that combine different processing principles. The present invention relates to a machining fluid supply device for use.

[Conventional technology]

In electric processing machines such as those mentioned above, various machining fluids such as water are used, but not only the characteristics of the machining fluid but also its supply amount change depending on changes in machining conditions such as during rough machining and finishing machining. It is necessary to make changes at the same time.

Conventionally, each time the machining conditions are changed, the characteristics of the machining fluid are changed by, for example, lowering the resistivity of the machining fluid using a conductivity adjusting fluid or increasing the resistivity using an ion exchange device. Since the flow rate of the machining fluid was adjusted so that the specified flow rate was supplied, it not only took time to adjust the quality of the machining fluid when switching from rough machining to finishing machining, but also caused problems with the ion exchange resin and conductivity. This method consumes a large amount of the adjustment fluid, which is uneconomical, and there is also the problem that the necessary machining fluid supply amount that matches the selected machining conditions must be determined from an instruction manual or the like.

For example, if we take a wire-cut electrical discharge machine as an example, wire-cut electrical discharge machines have recently been required to meet the two demands of high speed and high precision, and high-speed machining is already 100 to 200 mm2/min. has been achieved, and in high-precision machining, it has become possible to process with a finish roughness of 1 to 3 μRmax or less.

In machining that changes machining energy over a wide range like this, the energy of each unit discharge pulse due to machining voltage pulses supplied to the machining gap and the amount of discharge energy supplied per predetermined time are determined by the supply density of voltage pulses. The relationship between the electrode and the servo feed that sends the electrode or workpiece has become delicate, and machining stability and machining accuracy can be greatly improved by adjusting the specific resistance of the machining fluid, the hydraulic pressure of the machining fluid supplied, the flow rate of the machining fluid, etc. It will be different.

■ During normal machining, a large amount of water machining fluid with low resistivity is supplied, emphasizing high-speed machining, and conversely, during finishing machining, the resistivity is increased and the amount of water supplied is suppressed (in some cases, It is necessary to perform processing using a so-called oil processing fluid. Under high-speed machining conditions, if the specific resistance is high, the electrode material may adhere to the machined surface of the workpiece, making it impossible to obtain a stable machining speed at a high level, and electrode breakage due to large currents. This is because it is necessary to increase the amount of machining fluid supplied to improve cooling to prevent
This is because leakage current tends to cause rust and electrolytic corrosion, making the machined surface rough, and supplying a large amount of machining fluid causes the electrode to vibrate, making it impossible to maintain the machined surface and machining accuracy.

Therefore, it is necessary to change and control the properties of the machining fluid and the amount of machining fluid supplied in accordance with the machining conditions selected according to the purpose of machining.

Further, it is desirable to change the quality of the machining fluid according to the machining conditions, and to switch and control the flow rate and characteristics of the machining fluid at the start and end of machining and during corner machining (according to the corner angle).

In this case, if one processing liquid tank was used as in the past,
In order to adjust the specific resistance, for example, the ion exchange device must be operated for several hours or more. Further, when the supply liquid pressure or flow rate is manually adjusted by the operator, there is a problem that it is easy to waste work time and cause work errors.

In addition, machining conditions may be changed in several stages, even tens of stages, from rough machining to finishing, but the properties of the machining fluid and the amount of machining fluid to be supplied must be adjusted to suit the machining conditions at each stage without making mistakes. It was very difficult to set up and control, and there were operational problems.

[Problem that the invention seeks to solve]

The present invention has been made to solve the above problems, and its purpose is to quickly and appropriately supply an optimal machining fluid in response to changes in machining conditions in an electric processing machine. An object of the present invention is to provide a machining fluid supply device that obtains the desired results.

[Means for solving problems]

The above purpose is to provide at least two storage tanks that individually store at least two types of machining fluids having different properties, and to set at least one of the specific resistance, viscosity, or liquid temperature of the machining fluid in each of the storage tanks to a predetermined value. A device that controls the value of the machining fluid, a device that switches the supply flow rate of machining fluid in multiple stages, and a device that selects the machining fluid to be used from among the at least two types of machining fluids mentioned above during machining and switches the setting of the supply flow rate. This is achieved by providing a machining fluid supply device consisting of a control device and a control device.

[For production]

With the above configuration, the control device selects a predetermined machining fluid from a plurality of storage tanks in which machining fluids each having a predetermined specific resistance, viscosity, or liquid temperature are individually stored in accordance with changes in machining conditions. Since this is supplied to the processing machine at a predetermined supply liquid pressure and/or flow rate, the optimum processing liquid is quickly and appropriately supplied, which allows each stage of processing from high-speed processing to high-precision finishing processing to be performed quickly. It is something that will be carried out in the future.

〔Example〕

Hereinafter, the configuration of the present invention will be specifically explained with reference to the drawings.

The drawing is an explanatory view showing one embodiment of the machining fluid supply device for electrical machining according to the present invention. 1 and 2 are processing fluid storage tanks; 3 and 4 are sewage tanks attached to storage tanks 1 and 2, respectively, for storing processing fluid contaminated by processing; 5 and 6 are processing fluid supply pumps; 7 and 8 9 and 10 are joint flowmeters, 11 and 12 are flow control valves, 13 and 14 are check valves, and 15 and 16 are circulation for adjusting the quality of the processing liquid. Pumps 17 and 18 are motors 1 that drive the circulation pumps 15 and 16, respectively.
9 and 20 are ion exchange columns with precision filters, 21 and 22 are resistivity meters, 23 and 24 are pumps, 25 and 26
are motors that drive the pumps 23 and 24, respectively;
27 and 28 are controllers that control the liquid level in the waste liquid tanks 3 and 4 within a predetermined level range; 29 and 30 are filters;
1 is a resistivity detector for machining fluid; 32 is a drain switching valve that returns the machining fluid contaminated by machining to the dirty fluid tank 3 or 4; 33 is a control device that controls the operation of the entire machining fluid supply system; The electrical processing machine 35 is an NC device that controls the operation of the electrical processing machine.

The first machining fluid storage tank 1 stores a machining fluid with low resistivity that is used when performing normal rough machining with the electric machining machine 34, and the second machining fluid storage tank 2 stores a machining fluid that is used for finishing machining. Contains a machining fluid with high resistivity that is used when performing this process.

When performing rough machining first with the electric processing machine 34,
The NC device 35 that controls the operation of the electric processing machine main body 34 sends a signal a to the control device 33 to perform rough machining, and based on this, the control device 33 sends the machining fluid supply pump 5
At the same time as operating the motor 7 that drives the flow meter 9
The reference value of the flow rate to be controlled is commanded by the signal g. In such a case, the machining fluid with low resistivity in the first machining fluid storage tank 1 is supplied to the electric processing machine main body 34 by the pump 5 through the flow control valve 11, the check valve 13, and the resistivity detector 31.

At this time, the flow rate of the machining fluid is detected by the regulating flow meter 9, and a control signal is sent to the flow rate regulating valve 11 to maintain the supply amount of the machining fluid at a predetermined value.

Also, during machining from the start of machining to the end of machining, the NC device 3
If the signals programmed in No. 5 are sequentially output, the control device 33 outputs control signals accordingly to change and control the flow rate adjustment value. In this case, instead of adjusting the flow rate control valve 11 using the signal g, or at the same time, a signal may be sent to the inverter control drive circuit (not shown) of the motor 7 to change the rotation speed of the motor 7 (or pump 5). It can also be configured to adjust the flow rate.

On the other hand, when finishing processing is performed using the electric processing machine 34, the NC device 3 that controls the operation of the electric processing machine 34
5 sends a signal to the control device 33 of the machining fluid supply device to perform finishing machining, and based on this signal, the control device 33 operates the machining fluid supply pump 6.

In this case, the pump 6 supplies the machining fluid with high specific resistance in the second machining fluid storage tank 2 to the electric machining machine 34 through the check valve 14, the flow rate control valve 12, and the resistivity detector 31.

At this time, a reference value for the flow rate of the machining fluid to be controlled by the joint flow meter 12 is commanded by a signal, and the joint flow meter 12 operates based on the command, and the flow rate of the machining fluid to be supplied to the electric processing machine 34 is controlled. is controlled.

Also, like the regulating flowmeter 9, it can be configured to send a signal to the drive circuit of the motor 8 to control the flow rate.

The resistivity of the machining fluid supplied to the electric processing machine 34 is detected by the resistivity detector 31, and if this is lower than a predetermined appropriate value, A signal d is generated, and the control device 33 issues a control signal based on this signal to control the circulation pump 15 and motor 17 to maintain the specific resistance of the machining fluid in the machining fluid storage tank 1 or 2 at a predetermined value.
, ion exchange tower 19 or circulation pump 16, motor 18,
The ion exchange tower 2o is operated.

That is, first of all, speaking of the first machining fluid storage tank 1 that stores machining fluid for rough machining, the resistivity of the machining fluid sent from the storage tank 1 during rough machining is detected by the resistivity detector 31, and this is detected by the resistivity detector 31. If it is lower than a predetermined allowable lower limit value for machining, the control device 33 sends a signal i to the motor 17 that drives the circulation pump 15 of the first machining fluid storage tank 1 to operate it. In such a case, the processing fluid in the storage tank 1 is sent to the ion exchange tower 19 through the circulation pump 15, where it undergoes precision filtration and ion exchange, where it becomes pure water with high resistivity and is sent to the storage tank 1. be returned. Then, when the resistivity value of the machining fluid in the storage tank 1 decreases to a predetermined value, the control device 33 stops the motor 17 based on the signal d and/or the output signal e of the resistivity meter 21.

Note that it is desirable to use a device capable of differential operation, integral operation, feedforward control, etc. to control this ion exchange device.

On the other hand, the quality control of the machining fluid in the second machining fluid storage tank 2 that stores machining fluid for finishing is exactly the same as that of the machining fluid in the first machining fluid storage tank 1, and the signals d, j, f, so its explanation will be omitted.

The machining fluid contaminated with machining debris etc. due to being used in the electric processing machine 34 is collected into the waste fluid tank 3 or 4 via the drain switching valve 32 which is activated by a signal from the control device 33. It has become so.

The machining fluid collected in the sewage tank 3 is purified to a certain level through the filter 29 by the pump 23 operated by the motor 25 and returned to the storage tank 1, and is also collected in the sewage tank 4. The machining fluid is passed through a filter 30 to a storage tank 2 by a pump 24 operated by a motor 26.
each is returned to and reused.

Then, for example, the signal C is output from the NC device 35 for second finishing processing, and processing is performed one after another.

An example of the machining fluid supply performed by the machining fluid supply device configured as described above was as follows.

In addition, the conductivity during the second and third processing was 50μ.
・The fourth change from S to 30 μ·S was adjusted using the ion exchange method.

〔Effect of the invention〕

Since the present invention is constructed as described above, when using the machining fluid supply device for electrical machining according to the present invention, the optimal machining fluid can be supplied quickly and appropriately in accordance with changes in machining conditions in electrical machining. This makes it possible to supply machining fluid under optimal conditions over a wide range from high-speed rough machining to high-precision finishing machining.

Note that the configuration of the present invention is not limited to the above-mentioned embodiments, and more machining fluid storage tanks storing machining fluids with different characteristics may be provided, and pumps and valves may be arranged in multiple stages. It is also possible to change the flow rate and quality of the machining fluid in dozens of steps over a wide range by appropriately changing the combination of fluids. or temperature, or a combination of these (furthermore, there are cases where not only the amount of liquid to be supplied but also the liquid pressure is controlled, and various detectors,
The number and arrangement of valves, flowmeters, pumps, etc. can be changed as necessary, and therefore, the present invention includes all modifications that can be easily conceived by a person skilled in the art from the above description within the scope of its purpose. Examples are inclusive.

[Brief explanation of drawings]

The drawing is an explanatory diagram showing an embodiment of the machining fluid supply device for electrical machining according to the present invention.

Claims (1)

[Scope of Claims] At least two storage tanks each separately storing at least two types of machining fluids having different properties, and at least one of the specific resistance, viscosity, or liquid temperature of the machining fluid in each of the storage tanks. A device that controls the supply flow rate to a predetermined value, a device that sets and switches the supply flow rate of machining fluid in multiple stages, and a device that controls which of the at least two storage tanks should be used during machining according to a signal output from a numerical control device according to a preprogrammed program. A machining fluid supply device for electrical machining, comprising: a control device that selects and sets a combination of machining fluid selection and setting switching of its supply flow rate.