JPH0555256B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a machining fluid supply device for wire cut electric discharge machining that contains water as a main component (including cases where it is only water).

(Conventional technology) In wire cut electric discharge machining, pure water is generally used as a machining fluid, but electric field current is Due to the need to reduce machining and improve machining accuracy, for finishing machining after rough machining, it is necessary to use a machining fluid with a resistivity higher than that of the machining fluid used for rough machining up until now. It won't happen. Conventionally, in order to supply machining fluids with different specific resistances to the machining part, one
In order to increase the specific resistance of the machining fluid stored in the two machining fluid tanks as the machining progresses from rough machining to semi-machining to finishing machining, the machining fluid is passed through an ion exchange resin to undergo ion exchange. In this way, machining fluids with specific resistances suited to the purpose of machining are sequentially generated and used.

(Problems to be Solved by the Invention) Since it takes time to process the machining fluid using the ion exchange resin, when the machining is performed in stages from rough machining, semi-machining, and finishing machining, ions are Replacement requires time to process the machining fluid, and for this reason, conventional apparatuses have the problem that machining time is long and machining cannot be carried out efficiently. In the above, the treatment time for machining fluid by ion exchange is longer in areas with higher specific resistance, so it takes time to set up finishing machining, and after finishing machining, it is necessary to treat the same or another workpiece. In order to perform rough machining using a machining fluid, it is necessary to add and mix an appropriate conductivity modifier, etc. to the machining fluid to achieve a predetermined resistivity. It was a lot.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention is an electric discharge machining process that uses a machining fluid containing water as a main component. In a machining fluid supply device for wire cut electrical discharge machining that selectively supplies machining fluids with different specific resistances depending on the type,
a pre-treatment tank for receiving used machining fluid returned from the machining section; a first machining fluid tank for storing a first clean machining fluid; It has a second pump that pumps up and supplies the stored machining fluid to the machining section, and is connected to a second machining fluid tank that stores a second clean machining fluid that has a higher specific resistance value than the stored machining fluid in the first tank. The first and second machining liquid tanks each include first and second ion exchange automatic control devices for maintaining the specific resistance of the machining liquid stored therein at predetermined values, respectively, and It has a pump that pumps processing fluid from the processing tank.
a feedback circuit having a switching valve that switches and returns the pumped machining fluid to the first machining fluid tank and the second machining fluid tank via a filter; and the second machining fluid tank that supplies the machining fluid from the first machining fluid tank to the second tank. It is characterized by having an on-off valve provided in the discharge circuit of the pump. Further, the present invention includes a third pump and an ion exchange automatic control device for pumping and supplying the stored machining fluid to the machining section, and the third cleaning fluid having a specific resistance value higher than that of the stored machining fluid in the first tank. It is characterized in that a third tank for storing the machining fluid is connected to the second tank.

(Example) An example of the present invention will be described below with reference to FIG. In FIG. 1, 1 and 2 are nozzles that spray machining fluid onto the workpiece 3;
2 has means for positioning and guiding the wire electrode 4, and is provided facing both sides of the workpiece 3.

Reference numeral 5 denotes a processing tank for receiving the used processing fluid that has been sprayed and supplied to the processing section; 6, the processing tank 6 temporarily stores the used processing fluid introduced from the processing tank 5 through the pipe 7 for the purpose of sedimentation treatment of processing waste, etc.; 8 is a first machining fluid tank that stores the first cleaning fluid; 9 is a second machining fluid tank that stores the second cleaning fluid; each of these tanks is constructed in series. . The pretreatment tank 6, the first machining fluid tank 8, and the second machining fluid tank 9 are connected by pipes 12 and 12' having a pump 10, a filter 11, and a gate valve 12A. The machining fluid in the pre-treatment tank 6 is the machining fluid No. 1.
It is fed to tank 8. In addition, the height of the partition plate 13 between the two tanks 6 and 8 may be lowered so that the machining fluid in the pretreatment tank 6 flows into the first machining fluid tank 8 or vice versa due to overflow. be.

The first machining fluid tank 8 includes a machining fluid circulation pipe 1.
4, and a device for removing ions in the machining fluid, which is comprised of a pump 15 and an ion exchange resin 16 installed in the pipe, and a pipe that supplies the machining fluid in the first tank 8 to the nozzles 1 and 2. One end of the conduit 17 is immersed, and the conduit 17 is provided with a first pump 18 and an on-off valve 19. In addition, a sensor 20 that detects the specific resistance (or conductivity - the same hereinafter) of the machining fluid in the first tank 8 is connected to the nozzles 1 and 2 via a pipe line 17.
Sensor 2 that detects the specific resistance of the machining fluid supplied to
1, and by controlling the operation, stopping, or flow rate of the pump 15 by the controller 22 attached to the setting device 22a, which inputs the detection signals of these sensors 20 and 21, the exchange with the ion exchange resin 16 is performed. The specific resistance is controlled to be equal to or higher than a predetermined value by controlling the amount. The first tank 8 and 14-2
The device and parts shown in 2 constitute a first machining fluid supply device that supplies machining fluid with a relatively low specific resistance to the nozzles 1 and 2.

Between the first tank 8 and the second tank 9, the first
A machining fluid introduction conduit 24 is provided which branches from between the pump 18 and the on-off valve 19 and is provided with an on-off valve 23 . Similarly to the first tank 8, the second tank 9 includes a processing fluid circulation pipe 25, and an ion removal device for the processing fluid, which includes a pump 26 and an ion exchange resin 27 installed in the processing fluid circulation pipe 25. provided, and
One end of a conduit 28 for supplying the machining fluid in the second tank 9 to the nozzles 1 and 2 is immersed, and the conduit 28 has a second
A pump 29 and an on-off valve 30 are provided. Further, a sensor 31 that detects the resistivity of the machining fluid in the second tank 9 and a sensor 32 that detects the resistivity of the machining fluid supplied to the nozzles 1 and 2 via the pipe line 28 are provided. By controlling the operation, stopping, or flow rate of the pump 26 by the controller 33 attached to the setting device 33a, which receives the detection signals of these sensors 31 and 32 as input, the amount of exchanged by the ion exchange resin 27 is controlled and the specific resistance is adjusted. is configured such that it is equal to or greater than a predetermined value. The second tank 9 and 23 to 33
A second machining fluid supply device that supplies machining fluid with a relatively high specific resistance to the nozzles 1 and 2 is configured by the device and parts shown in FIG.

The machining fluid supply pipes 17 and 28 are connected to a common pipe 34.
The common pipe line 34 branches into pipe lines 35 and 36 which are connected to the nozzles 1 and 2, respectively, and each pipe line 35 and 37 has a variable throttle valve 37 for adjusting the flow rate.
38 are provided.

In this example, the lower limit of the specific resistance of the machining fluid (pure water) used for rough machining, semi-machining, finishing machining, and super finishing machining is set to, for example, 3×10 ⁴ Ωcm.
(Suitable for rough machining at a machining speed of approximately 150 to 320 mm ² /min), 10 × 10 ⁴ Ωcm (Suitable for medium machining and finishing machining at a machining speed of approximately 100 mm ² /min or less),
80×10 ⁴ Ωcm (machined surface roughness is approximately 5μmRmax)
(suitable for super finishing). First, during rough machining, the on-off valve 19 is closed and the first
The setting value is set to 3× by the setting device 22a so that the specific resistance of the machining fluid in the tank 8 is 3×10 ⁴ Ωcm or more.
The setting value is set to 10 ⁴ Ωcm or more, and the controller 22 operates the pump 15 based on the detection signal from the sensor 20 to circulate the processing fluid in the first tank 8 through the ion exchange resin 16 to remove ions. As a result, when the specific resistance of the machining fluid in the first tank 8 reaches a predetermined value that is higher than the lower limit value during rough machining, the on-off valve 19 is opened, the pumps 10 and 18 are operated, and the machining fluid in the first tank 8 is processed. Liquid to pipes 17, 34, 35, 36
It is ejected from the nozzles 1 and 2 to the processing section through the nozzles 1 and 2.
In addition, the adjustment operation of the resistivity of the machining fluid as described above is as follows:
During daily use other than when the machining fluid in the first tank 8 is replaced, etc., it is hardly necessary other than a training run at the start of work in the morning, and when replacing the machining fluid, on the contrary, a conductivity regulator is added. Sometimes mixed. During the rough machining, the specific resistance of the machining liquid supplied to the nozzles 1 and 2 can be adjusted by the sensor 20 as appropriate, but usually it is adjusted by the detection signal of the sensor 21 provided in the conduit 17. By controlling the pump 15 by the controller 22, the pump 15 is adjusted to maintain a predetermined value that is greater than or equal to the set value.

In addition, while performing machining using this first tank 8, or in advance during finishing machining, etc., in the second tank 9, the set value is set to the lower limit for semi-machining and finishing machining using the setting device 33a. The value is set to a predetermined value of 10×10 ⁴ Ωcm or more, the specific resistance of the machining fluid in the tank is measured by the sensor 31, and the pump 26 is controlled via the controller 33, thereby controlling the second tank 9.
The specific resistance of the machining fluid in the wafer is set to a predetermined value that is equal to or higher than the lower limit value during the intermediate machining and finishing machining.

When the above-mentioned rough machining is completed and the transition is made to semi-machining and finishing machining, the on-off valve 19 is closed, the on-off valves 23 and 30 are opened, and the machining fluid is transferred to the first tank 8 and the second tank 9.
By supplying machining fluid to the nozzles 1 and 2 without using the first tank 8 by switching the switching valve 12A to the pipe line 12' side, it is possible to immediately proceed to semi-finishing and finishing machining. .

In addition, when moving to super finishing machining, either a third machining fluid tank with a higher specific resistance of the machining fluid is provided in advance, or after finishing machining, the setting device 31a is set to a predetermined value and the second tank is opened. Normally, the machining fluid in the pipe is used after being subjected to ion exchange treatment, but the set value of the setting device 22a of the first tank 8 is changed during the semi-machining and finishing machining. The resistivity of the machining fluid inside the first tank 8 is increased to a value suitable for semi-machining and finishing machining by setting it to a predetermined value that is higher than the lower limit value and causing the ion exchange resin 16 to work.
The on-off valve 19 is opened and the switch is made so that most of the supply from the first tank 8 is supplied to the nozzles 1 and 2. During this time, the setting value of the setting device 33a is set to a predetermined value that is higher than the lower limit value for super finishing processing, and the second It is also possible to set the resistivity of the machining fluid in the tank 9 to a resistivity value suitable for super-finishing. In the case of such super finishing processing, a multi-stage process is performed in which the recovered machining liquid in the pre-treatment tank 6 is subjected to ion exchange treatment in the first tank 8 and then supplied to the second tank 9 for processing and use. By performing the treatment, it is possible to stably supply a machining fluid with a predetermined high resistance. By doing so, machining can be performed without waiting time during machining switching when transitioning from rough machining to medium machining and finishing machining, and from finishing machining to super finishing machining.

In addition, as in this example, the lower limit values of the resistivity of the machining fluids used in rough machining, semi-machining, and finishing machining are similar, and the ratio of machining fluids used in semi-machining, finishing machining, and super finishing machining is similar. If the lower limit values of resistance are far apart, the machining fluid is supplied to the nozzles 1 and 2 through the first tank 8 during rough machining, semi-machining, and finishing machining, and the machining fluid is supplied to the nozzles 1 and 2 through the first tank 8 during super finishing machining. Once the machining fluid is introduced into the second tank 9, the nozzle 1,
2 may be supplied. In this case,
Only the waiting time required when transitioning from relatively time-consuming semi-finishing and finishing to super-finishing can be omitted.

Note that the machining fluid in the second tank 9 is also used as cooling water for the current-carrying pin portion. In addition, instead of performing machining in four stages as described above, in cases where finishing machining is performed immediately after rough machining, etc.
If it is sufficient to change the resistivity of the machining fluid in two stages, there is no need to perform an operation to increase the resistivity of the machining fluid before finishing.

FIG. 2 shows another embodiment of the present invention, in which a third machining fluid tank 40 for storing a third cleaning fluid is provided in addition to the second tank 9 as a machining fluid supply tank.
The third tanks 8, 9, and 40 are adapted for rough machining, medium machining, finishing machining, and super finishing machining, respectively. If the super finishing process is omitted, each of the tanks 8, 9, and 40 may be suitable for rough processing, semi-finishing, and finishing, respectively.

In this embodiment, between the second tank 9 and the third tank 40, a machining fluid introduction pipe 42 is branched from between the second pump 29 and the on-off valve 30 and is provided with an on-off valve 41. is provided. Similarly to the first tank 8 and the second tank 9, the third tank 40 includes a processing fluid circulation pipe 43 and a pump 4 installed in the pipe.
4 and an ion exchange resin 45 is provided, and one end of a pipe line 46 for supplying the processing liquid in the third tank 40 to the nozzles 1 and 2 is immersed. 46 is provided with a third pump 47 and an on-off valve 48. In addition, the third tank 4
a sensor 49 that detects the specific resistance of the machining fluid within 0;
A sensor 50 is provided to detect the specific resistance of the machining fluid supplied to the nozzles 1 and 2 via the pipe line 46, and the controller 51 attached to the setting device 51a receives the detection signals from these sensors 49 and 50 as input. By controlling the operation, stopping, or flow rate of the pump 44, the amount of exchange by the ion exchange resin 45 is controlled so that the specific resistance becomes a predetermined value or more.

In the embodiment shown in FIG. 2, the specific resistance of the machining liquid in the second and third tanks 9, 40 is set to the respective lower limit values, 10× Ions are removed using the ion exchange resins 27 and 45 so that predetermined values of 10 ⁴ Ωcm and 80×10 ⁴ Ωcm or more are obtained.

According to the embodiment shown in Fig. 2, when setting three types of machining fluid resistivity for rough machining, semi-machining, finishing machining, and super-finishing, the machining fluid before semi-machining, finishing machining, or super-finishing machining is Since no time is required for the specific resistance increasing operation, processing can be performed more efficiently and with easier operation than in the embodiment shown in FIG.

FIG. 3 further shows another embodiment of the present invention, which is a modification of FIG. , a pump 10 that supplies machining fluid from the previous stage,
18 is used to feed the processing fluid to the ion exchange resins 16 and 27.
That is, for the first tank 8, the pump 10
A switching valve 1 of the pipe line 12' is installed in the middle of the pipe line 12 equipped with a
A switching valve 52 is provided in addition to 2A, and two ports on the secondary side of the switching valve are connected to a pipe line 53 that directly introduces the machining liquid into the first tank 8 and a pipe line 54 that contains the ion exchange resin 16. and the controller 22
By switching the switching valve 52 with
It is designed to be introduced into tank 8. Similarly, regarding the second tank 9, the machining liquid supplied to the pipe line 24 via the on-off valve 23 or the pipe line 12' is controlled by the switching valve 55 operated by the controller 33, the pipe line 24,
56 and an ion exchange resin 27.

In this embodiment, for example, when rough machining is being performed, the first pump 18 is operated to supply machining fluid to the nozzles 1 and 2 via the pipe line 17 and the on-off valve 19, and at the same time, when necessary The on-off valve 23 is opened accordingly, and some of the machining fluid flows through the pipe line 24,
The processing liquid is introduced into the second tank 9 via the switching valve 55 and the ion exchange resin 27, and the second tank 9 is configured to return some of the processing liquid to the first tank 8 by an overflow partition. 31 so that the specific resistance of the machining fluid in the second tank 9 is a predetermined value that is higher than the lower limit value during semi-processing and finishing. By closing the on-off valve 19 and supplying the machining fluid to the nozzles 1 and 2 through the first tank 8 and the second tank 9, it is possible to immediately proceed to intermediate machining and finishing machining.

In addition, when moving to super finishing machining, setter 2
The set value of 2a is set to a predetermined value that is higher than the lower limit for semi-processing and finishing processing, and the ion exchange resin 16
is activated to raise the specific resistance of the machining fluid inside the first tank 8 to a value suitable for medium machining and finishing machining, and the on-off valve 19 is opened to supply most of the fluid from the first tank 8 to the nozzles 1 and 2. During this time, the setting value of the setting device 33a is set to the lower limit value for super finishing machining so that the resistivity of the machining fluid in the second tank 9 becomes a resistivity value suitable for super finishing machining. You can also. After the intermediate machining and finishing machining are completed, the on-off valve 19 is closed and the liquid in the second tank 9 is used to perform super finishing machining. By doing so, machining can be performed without waiting time when switching machining. Note that in this embodiment as well, the third tank 4
It is also possible to provide zero or even a fourth tank.

(Effects of the Invention) As described above, according to the present invention, two or more machining liquid tanks are installed to store machining liquid having a resistivity value suitable for each machining stage, so that machining stages can be switched. This eliminates the need for operation time such as ion exchange to increase the specific resistance of the machining fluid, resulting in the advantage that electrical discharge machining can be carried out efficiently. In addition, in the present invention, since a plurality of machining liquid tanks are arranged in series, compared to a system in which a plurality of machining liquid tanks are lined up and each has its own independent machining liquid supply system, this type of machining liquid supply system is more economical. An inexpensive product with less space and fewer parts can be obtained. In addition, in the present invention, it is possible to further process and use the machining fluid treated in the previous stage in the next stage, so compared to the above-mentioned parallel installation type, it is possible to achieve a stable and reliable higher resistivity. Machining can be performed using machining fluid.

[Brief explanation of drawings]

1 to 3 are apparatus configuration diagrams each showing an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. Electrical discharge machining using a machining fluid containing water as a main component, in which a wire-cut electrical discharge that switches and supplies machining fluids with different specific resistances depending on the purpose or type of machining to be performed subsequently. The machining fluid supply device includes a pre-treatment tank for receiving used machining fluid returned from the machining section, and a first pump that pumps up and supplies the stored machining fluid to the machining section, and supplies the first clean machining fluid to the machining section. and a second pump for pumping up and supplying the stored machining fluid to the machining section, and storing a second clean machining fluid having a higher resistivity value than the machining fluid stored in the first tank. The first and second machining fluid tanks are equipped with first and second ion-exchange tanks for maintaining the specific resistance of the machining fluid at predetermined values, respectively. a feedback circuit comprising an automatic control device, further comprising a pump for pumping up the machining fluid from the pretreatment tank, and a switching valve for switching and returning the pumped machining fluid to the first and second machining fluid tanks via a filter; and an on-off valve provided in a discharge circuit of the first pump that supplies the machining fluid in the first machining fluid tank to a second tank. 2 A machining fluid supply device for wire cut electrical discharge machining that uses a machining fluid whose main component is water, and which switches and supplies machining fluids with different specific resistances depending on the purpose or type of machining to be performed subsequently. The system includes a pre-treatment tank for receiving used machining fluid returned from the machining section, a first pump for pumping up and supplying the stored machining fluid to the machining section, and a machining fluid tank for storing the first clean machining fluid. 1 tank, and 2 machining fluid tanks that have a second pump that pumps up and supplies the stored machining fluid to the machining section, and that stores a second clean machining fluid that has a higher resistivity value than the stored machining fluid in the first tank. , a third pump for pumping and supplying the stored machining fluid to the machining section, and connected to a third machining fluid tank that stores a third clean machining fluid having a higher specific resistance value than the stored machining fluid in the second tank. The first, second and third machining fluid tanks each have first, second and third ion exchange automatics for maintaining the resistivity of the machining fluid stored therein at a predetermined value, respectively. a feedback circuit comprising a control device, further comprising a pump for pumping up the machining fluid from the pretreatment tank, and a switching valve for switching and returning the pumped machining fluid to the first and second machining fluid tanks via a filter; , an on-off valve provided in a discharge circuit of the first pump that supplies the machining fluid in the first machining fluid tank to a second tank; and the on-off valve that supplies the machining fluid in the second machining fluid tank to a third tank. A machining fluid supply device for wire cut electric discharge machining, characterized in that it has an on-off valve provided in a discharge circuit of two pumps.