JPH06320342A - Wire cut electric discharge machining method - Google Patents

Abstract

PURPOSE:To finish a work surface in a short time into a mirror or mirror-state glossy surface by setting a specific machining condition in the case of applying powder-mixed electric discharge machining of using an oily electric discharge machining fluid as the final finish machining. CONSTITUTION:In the case of executing final finish machining, a machining fluid is switched to a powder-mixed machining fluid for widening a machining clearance by a machining fluid switching control unit 19. Consequently, in order to prevent excessive machining of exceeding a prescribed contour line, machining is performed by setting an offset value of a wire electrode 4 increased by a prescribed amount larger than an offset value in the case of a final work process of an intermediate finish work process. While holding machining clearance mean voltage during this machining to a value sufficiently higher than that in the intermediate finish machining process, a machining feed is controlled by an NC control unit 15. As a result, a work surface of a workpiece 3 is finished to a desired mirror or mirror-state glossy surface.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wire cut electric discharge machining.
Method, especially final finishing by wire-cut electrical discharge machining
It has excellent surface roughness due to machining, and also has a mirror-like luster.
And an improved processing method for obtaining a finished surface. [0002] Conventionally, this type of wire-cut electric discharge machining is
Place the guides in a specified state between a pair of spaced guides.
While moving the suspended wire electrode in the axial direction,
From the direction substantially perpendicular to the axis direction, through the work piece with a minute gap
In the state that they are opposed to each other and the machining fluid is supplied to the gap.
A discharge pulse generated by applying an intermittent voltage pulse between them.
Between the wire electrode and the work piece
In the predetermined machining contour shape on the plane of the right angle direction
Along the relative machining feed
Processing such as cutting and cutting is performed. According to such a wire cut electric discharge machining method
Process and finish various molds, members, parts, etc.
First, the wire-cut electric discharge machining described above
Depending on the material of the work piece, the plate thickness, the purpose of the work, etc.
Electrode material, wire diameter, tension applied to the processed part tension, and renewal
The speed and other factors can be selected and set.
Shape, and especially electrical conductivity, and further spraying and dipping of working fluid
Select and set the supply intervention method such as
At the same time, the machining feed rate such as machining feed speed and servo control
Conditions, and the voltage value for processing or the voltage value of the discharge pulse,
Electrical processing of electric pulse width, pause width, discharge current amplitude, etc.
Select and set the conditions and place between the wire electrode and the work piece.
A certain machining contour line shape is offset by a specified amount along the trajectory.
It is the first to give a machining feed while controlling it by a numerical controller.
First cut to process and form the machining groove of
Work). Next, after the first cut processing,
Predetermined second cut of various set processing conditions (medium processing)
While changing the setting to the processing condition,
The offset for the constant machining contour line shape is switched and added.
Work, then for the third cut processing in the next processing step
Usually, the above-mentioned first cut processing is performed so that it will be transferred sequentially.
From (rough machining) to medium machining, semi-finishing machining, finishing machining,
And, like the final finishing process, the process of 3 to 7 steps
For finishing the processed body to the specified dimensional accuracy and surface roughness.
(For example, JP-A-57-102724,
(See Japanese Patent Publication No. 1-454523). However, the conventional method
According to the kind of wire cut electrical discharge machining method, pay close attention
Pay enough time, and expect a sufficient degree of safety, and take time
The processed surface roughness is about 1.5-3.0
Machining accuracy of about ± 2 to 5 before or after μmRmax
Although it is possible to process around μm, for that purpose
It was a fairly difficult process that required considerable experience and skill. In addition, the high precision precision products and parts as described above.
For products, etc., to improve surface roughness or to improve accuracy
For improvement, a great deal of work is required after the above wire-cut electric discharge machining.
There are cases where polishing processing that requires time, time and skill is required.
Many were expensive. The present invention has been made in view of the above points.
Therefore, the polishing process of the above final processing step is practically necessary.
No mirror surface or mirror surface that is far superior to conventional examples
The glossy finished surface of the
Relatively easily and in a significantly shorter time than before, and
Plate thickness of 10 mm or less, which has been difficult to perform mirror-like processing
Even for a workpiece with a large processing area above, in a short time, and
Make sure to finish the mirror surface or the mirror-like glossy surface.
To provide a wire-cut electrical discharge machining method capable of performing
With the goal. The above objects and problems are as follows.
(1) Predetermined shape between a pair of guides arranged with a gap.
The wire electrode stretched in a stationary state is updated and moved in the axial direction.
At the same time, make a small gap in the work piece from a direction substantially perpendicular to the axial direction.
To face each other with the machining liquid supplied to the gap.
In this state, an intermittent voltage pulse is applied between the two
Processed by electric pulse and processed with the wire electrode
Predetermined work forming on the plane in the perpendicular direction between the bodies
Wire cutter that provides relative machining feed along the power contour shape
In wire-cut EDM, the wire-cut EDM described above
The material to be processed, the plate thickness, the purpose of processing, etc.
Depending on the processing conditions selected and set according to
Along a trajectory that is offset by a specified amount from a specified contour line
First-cut machining process to machine and form the first machining groove
And, after the first cut processing, the setting condition is set to a predetermined value.
More than one processing step such as second cut and third cut
The workpiece to be processed is sequentially switched to the processing conditions of the above respective processing steps.
The machined surface roughness of the
Semi-finishing process that sequentially processes the process.
And switching the above processing conditions to predetermined processing conditions
In addition, mix the powder with the machining liquid that will be supplied to the machining gap.
Switch to the oil-based machining fluid, and match the prescribed contour line shape.
The relative wire electrode offset value
From the offset value in the final processing of the lifting processing
Increase the specified amount and set the average value of the machining gap during machining.
The pressure is much higher than that of the previous semi-finishing process.
To control the machining feed so that final machining is performed.
(2) The processing method of (1) above
Method, the processing gap in the first cut processing step
A pure water-based machining fluid is added to the machining fluid supplied to the
Working liquid after the above-mentioned intermediate finishing process
Processing method that switches to oil-based processing liquid for processing
(3) In the processing method of (1), (2) or (3) above
Supply in the machining gap in the above-mentioned intermediate finishing process.
As a machining fluid to be used, powder was mixed with oil-based electric discharge machining fluid.
A processing method using a processing liquid, (4) above
In the processing method of (1), (2) or (2), the above
With wire electrodes in the finishing process
A relative offset between the workpieces and the predetermined contour line shape.
The fset value is made smaller or almost the same every time the machining conditions are changed.
Set to one so that the above sequential processing steps can be performed.
Processing method, (5) above (1), (2), (3) or
In the processing method of (4), in the final finishing process step
In the voltage pulse application discharge circuit in the inductor of a predetermined value
Switch the discharge circuit so that it is inserted in series.
Processing method, (6) above (1), (2),
In the processing method of (3), (4) or (5), the maximum
Oil-based electric discharge processing used for switching in the final finishing process
The working fluid is a hydrocarbon-based electric discharge machining fluid with a particle size of less than 5 μmφ,
Weigh silicon powder with an average particle size of 0.1 μmφ or more
A processing method containing 0.5% or more and less than 5% by percentage,
(7) The above (1), (2), (3), (4), (5) or
In the processing method of (6), the final finishing step
The machining in is in line with the predetermined machining contour line shape.
Machining feed of at least two processes on the increased offset trajectory
It is a cut process that depends on the plate thickness of the workpiece.
Processing that increases the number of processing steps
Method, (8) above (1), (2), (3), (4),
In the processing method of (5), (6) or (7), the maximum
During the set machining conditions in the final finishing process, the gap mark
Apply the no-load voltage of the applied voltage pulse to the above-mentioned intermediate finishing
Set to a value that is sufficiently higher than the set no-load voltage
The processing method to be performed, (9) above (1),
(2), (3), (4), (5), (6), (7) or
In the processing method of (8), in the final finishing process step,
In the processing conditions set in
In the final processing step of the semi-finishing processing step before the above
The pulse width is set larger than the pulse width
Select a factor from 60% to 95% and process it.
Processing method, (10) above (1), (2),
(3), (4), (5), (6), (7), (8) or
In the processing method of (9), in the final finishing process step,
The control of the machining feed in the
70% or more of no-load voltage of gap applied voltage pulse, about 8
Machining while controlling so as to maintain around 0 to 90%
To achieve by adopting the processing method
You can The most conventional wire-cut electric discharge machining
First of the 1st process where processing is executed under the mode and conditions
After the cutting process, it is preferable to add as a second processing process.
A normal hydrocarbon oil-based electric discharge machining fluid is used as the working fluid.
More than one processing step such as second cut and third cut
10 by the semi-finishing process that performs the above series of processing
Single-digit μmRmax with surface roughness smaller than μmRmax
First cut processed surface up to the specified surface roughness of order
After finishing, the surface to be finished is, for example, disclosed in JP-A-2-83.
119 and JP-A-3-277421.
Powder-type electric discharge machining such as
Set with various conditions and apply, that is, voltage pulse etc.
The processing conditions can be changed to specific conditions and
An oil in which a liquid is mixed with a powder of silicon or the like having a predetermined particle size in a predetermined ratio.
Switch to the system electric discharge machining fluid and supply it to the machining gap to make it final
Be sure to do the finishing, and this final finishing
Process, the working fluid is mixed with powder to widen the working gap.
Since it has been switched to the injection liquid, the specified contour line
Offset the wire electrode to prevent excessive machining.
Value at the time of the final processing step of the previous semi-finishing processing step
Set a certain amount larger than the offset value to perform machining
And the machining gap average voltage during machining.
Is a value that is sufficiently higher than that of the previous semi-finishing process,
For example, the no-load voltage of the machining voltage pulse applied to the machining gap
70% or more, 80-90% or more
Control the machining feed so that machining is performed while maintaining the above value
By doing so, it is possible to process thin workpieces.
From the body up to the thick one, the above final processing according to the increase in plate thickness
Skills are required by increasing the number of processing operations in the process.
Without anyone, surely and in a short time, for example, JP-A-62-
Surface substantially equivalent to the surface layer referred to in Japanese Patent No. 24916
To make the processed surface a desired mirror surface or a mirror-like glossy surface.
Can be finished. FIG. 1 shows a wire-cut electric discharge machining method according to the present invention.
1 is an XY cross station. FIG.
Processing tank 3 mounted on the bull 2 is shown in the processing tank 1
Connected and held to the XY cross table by the no stage
The workpieces 4 are usually arranged in the processing tank 1 in a predetermined vertical direction.
A pair of machining fluid injection nozzles placed facing each other with a gap
Positioning guide in the guide block bodies 5 and 6 that are also used
With a wire electrode stretched in a predetermined state between 5a and 6a,
Storage, supply, recovery mechanism and tension of wire electrodes (not shown)
The force-applying mechanism causes the feed to move in the axial direction,
The wire electrode 4 between the guides 5a and 6a is substantially perpendicular to the axial direction.
Drive from each direction by the X and Y axis drive motors 7 and 8
Processed by being fed and moved from the cross table 2
It is made to face each other with a small electric discharge machining gap with the body 3.
It Reference numeral 9 is a main power supply provided together with the sub power supply 10.
A power supply that has an on / off switching element such as an industrial FET.
A loose power source, the output of which is processed by the switch 11
Power supply terminals 5b and 6b in the body 3 and the guide block bodies 5 and 6
Polarity switch (not shown) between the wire electrode 4 and
Normally, the work piece 3 is the positive electrode and the wire electrode 4 is the negative electrode.
And the work piece 3 and the wire electrode, which are connected in a so-called positive polarity.
No load voltage (Vn) between 4 and pulse width (τ
ON), pause width (τOFF), and based on the voltage pulse
The current amplitude (IP) of the generated discharge pulse is
Via the processing power source switching means 13 by the signal from the device 12.
Intermittent voltage pulse that can be set to each predetermined value is applied.
Supplied. The auxiliary power supply 10 has a short pulse width
The anti-circuit increases the current amplitude of the main power discharge pulse and increases the machining amount.
Pulse power supply to increase significantly due to large, and short circuit current is small
A relatively high voltage DC power supply limited to
When voltage or short circuit occurs, voltage application is cut off (short circuit cutoff).
Gap state detection (of disconnection), gap length expansion, and instantaneous discharge
One or both of the sub power supplies (2) for fine processing. Reference numeral 14 is an indexer that can be set to a predetermined value.
The power source for processing is a coiled wire with a changer 11.
In series with the discharge circuit of the gap applied voltage pulse from 9, 10
It is provided so that it can be inserted and removed, and is mainly used when the wire ring 14 is inserted.
Suppress the rise of discharge current based on the voltage pulse
Reduce the impact force of the discharge, and
Delay the end of discharge pulse due to the end of the
Increase the discharge pulse width. Reference numeral 20 is an electric discharge between the wire electrode 4 and the workpiece 3.
A detection device that detects the discharge state of the machining gap.
A control signal for processing condition control and feed control is supplied to the table 12.
It Reference numeral 15 denotes the X-axis and Y-axis drive motors 7,
8 is operated to operate the workpiece 3 and the wire electrode.
Predetermined program on the plane at right angles between 4
The above-mentioned control of relative machining feed along an equal contour line shape
An NC control device that is executed under the control of the device 12, and will be described later.
Multiple wire-cut electrical discharge machining processes
Each desired machining feed rate and its overrun
Ride value can be set and wire electrode 4
The contour line shape to be processed and formed between the workpiece 3 and the workpiece 3
The offset value relative to
Therefore, it can be set and executed. 5c and 6c extend along the wire electrode 4 and
On jetting the working liquid from both sides of the working body 3 or one of the desired ones
The lower working fluid jet nozzle. 5d and 6d are guides
Each of the lock bodies 5 and 6 is provided with nozzles 5c and 6c.
The working fluid ejection side, the guides 5a, 6a and the power supply terminals 5b, 6b
Partitioned with the cavity side to be stored except the wire electrode insertion part
The partition wall can be opened and closed as needed.
Is configured as follows. Then, the electric discharge processing at the time of wire cut electric discharge machining
As an aspect of the intervention of supplying the working liquid to the work gap, the above-mentioned working
Supply and fill the tank 1 with the machining liquid, and at least the machining gap
While being immersed in the filling processing liquid,
A temperature controller is provided for the machining fluid in tank 1 if necessary, as described below.
Machining while circulating and flowing with the machining fluid supply device
How to do it, and in addition to this, processing tank 1
A different type of working fluid that is the same as or different from the fluid that flows in the upper and lower
Spout from both or one of the cheats 5c and 6c, or from one
A mode in which processing is performed while ejecting and sucking from the other side,
The processing tank 1 should be kept in a state in which the processing liquid etc. does not accumulate.
Process liquid from one or both of the upper and lower nozzles 5c and 6c.
While ejecting, or ejecting from one and sucking from the other
There is a mode of processing. 16 is for wire-cut electric discharge machining of the present invention
At the time of first processing the workpiece 3, that is, if desired.
Under the processing conditions selected and set,
The wire electrode 4 is relatively offset from the contour line to be offset.
A fur that processes and forms the first machining groove along the traced path.
Used during strut processing (usually high-speed rough processing)
It is a circulating supply device for the working fluid. In addition, 17 is the firth
After finishing the cut processing, set the above processing conditions to the specified
Each processing of more than one processing process such as hand cut and third cut
Machining the workpiece by sequentially switching to the machining conditions of the machining process
Smaller surface roughness, at least 5-6 μm before Rmax
Follow the machining process until the specified value is reached to a later level or less.
Used during the semi-finishing process in which
It is a circulating supply device for the working fluid. And 18 is the above intermediate
After the finishing process is completed, the above-mentioned processing conditions are changed according to the present invention.
In addition to switching to the working conditions, supply intervenes in the machining gap
Cutting the machining fluid into oil-based electric discharge machining fluid mixed with powder such as silicon
In addition, relative work to the predetermined contour line shape is also performed.
The offset value of the ear electrode is
If you set a predetermined amount larger than the offset value of the final machining process
In both cases, the machining gap average voltage during machining is the same as before before.
Control the machining feed to be sufficiently higher than that of the machining process
In the final finishing process in which the
It is a device that supplies an oil-based electric discharge machining liquid mixed with powder. Each of these machining fluid supply devices 16, 17 and
And 18 are created according to the purpose from the control device 12, etc.
Depending on the control signal of the program etc. that is set, each machining process
It is used by switching through the working fluid switching means 19. Na
In the figure, 16a, 17a and 18a are the respective working fluids.
The cleaning liquid tank of the supply device, 16b, 17b and 18b are also the same.
Contaminated liquid tank, 16c, 16d, 16e, 17c, 17d,
18c and 18d are pumps, 16f, 16g, 17
f, 17g, 18f and 18g are on-off valves, 16h, 1
7h and 18h are filters, 16i is ion exchange resin equipment
, 17i and 17j are throttle valves, 17k is a flow control valve,
18i is a backwash filter, 18j and 18k are open / close valves,
Further, 1a is an opening / closing valve, 5e and 6e are flow rate adjusting valves.
Each processing step of the above three steps will be described. First, the first cutting process of the first processing step
During the process, the machining fluid supply device 16 and the control device 12 and
And the working fluid switching means 19 brings the switching operation state into operation.
Work is done. At that time, the first cut processing step
Is important in terms of processing accuracy, processing progress, etc. in terms of overall processing efficiency.
Machining can be completed faster and in a shorter time, as long as there is no effect.
Is most commonly used as a working fluid,
Specific resistance value x × 10 ^Four Pure water-based working fluid of around Ωcm
Often used, but depending on the purpose of processing, etc.
A water-based machining fluid with various additives added to a pure water-based machining fluid
Used or silicon grain, carbon grain, aluminum
Water-based or oil-based electrical discharge machining fluid mixed with particles, iron powder particles, etc.
Electric processing such as voltage pulse set for processing time
Oil-based electric discharge machining fluid is used to compensate to some extent depending on the conditions.
It may also be used, but here the pure water-based processing liquid is used.
The case of use will be described. The cleaning liquid tank 16a includes a filter 16h.
Ion exchange resin device 16i
Removes ions, etc., and electric conductivity (specific resistance value)
The pure water-based working fluid adjusted to the specified value is managed and stored.
Pump 16c, open / close valve 16f, and upper and lower nozzles 5c,
Jetting to the processing section via the flow rate adjusting valves 5e and 6e of 6c
The working fluid supplied and processed is opened from the processing tank 1.
It is collected in the polluted liquid tank 16b via the closing valve 16g,
Recycled by pump 16d of circuit 16h
It Note that the processing accuracy, the purpose of processing, and the processing
If the working fluid is flammable, fill the working tank 1 with the working fluid.
In the case of so-called liquid immersion processing, open the on-off valve 1a and process
The tank 1 is filled with the working liquid. Therefore, in this case, as described above,
Since it corresponds to processing, the output of the power supplies 9, 10
Electric discharge time between the electric discharge machining gap between the workpiece 3 and the wire electrode 4
Inductance component that distorts the discharge current waveform in the path,
It is better to reduce the resistance component that decreases the current amplitude.
The safety resistance, etc. not shown in the figure are excluded.
The switch 11 excludes the inductance 14 from the discharge circuit
The processing is performed by switching as described above. Examples of processing and processing conditions at this time are as follows.
Show. [Experimental Example 1] (Fast cut setting processing conditions) Workpiece material SKD-11 Plate thickness 20 mm Wire electrode material 4: 6 Brass wire diameter 0.20 mmφ Applied tension 1.2 kgf Renewal feed rate 6.0 m / min Working fluid material Pure water specific resistance 5 × 10 ^Four Ωcm Nozzle aperture (up and down) 6mmφ Discharge flow rate (up and down) 6l / min Main power source no-load voltage 80V Voltage pulse Polarity: Positive on-time (τ _ON ) 1 μS Off time (τ _OFF ) 15 μS Current amplitude (IP) 12 A Sub power supply (which is applied in synchronization with the voltage pulse of the main power supply) No load voltage 265 V Voltage pulse on time (τ _ON ) 1 μS Off time (τ _OFF ) 15 μS Current amplitude (ip) 800 A Machining feed rate approx. 5 mm / min Servo voltage (average machining voltage) approx. 35 V Offset amount approx. 180 μm According to the preset machining conditions, average machining current approx. 9.8 A
The processing is performed at about 80% of the set feed speed.
The roughness was about 18 to 20 μm Rmax. Next, the above-mentioned intermediate finishing step is called
Depending on the machining process, and this is a pure water based machining liquid
When using a liquid, add an oil system to the processing liquid before and after the three processing steps.
When using a working fluid, the processing steps before and after 4-5 processing steps
By performing sequentially, it is preferable to finally obtain the finished surface roughness.
Is around 4 to 6 μm Rmax, and with special care
Approximately 1.5 to 3 μmR when the machining process is repeated many times
It is finished up to about max. In the following, in the above-mentioned semi-finishing process step, a processing liquid is prepared.
The case of using an oil-based electrical discharge machining fluid will be described below.
The operation of the machining fluid supply device 16 was stopped, and the oil-based electric discharge machining fluid was supplied.
The processing liquid supply device 17 for storing and supplying is operated. In addition,
Here and in this specification, oil-based (electrical discharge) machining fluid is used for engraving and drilling.
Hydrocarbon oils of the 4th class and 3rd class petroleum, which are commonly used in hole electrical discharge machining,
Chikerosine or white kerosene is used to lower the flash point.
There are slight additives and so on. The companion
The operating state of the feeder 17 is the same as that of the feeder 16 described above.
It is almost the same as
No ion exchange resin equipment is required. However, with processing fluid
Since it is flammable, the machining tank 1 is filled with oil-based electric discharge machining fluid.
However, the electric discharge machining gap between the workpiece 3 and the wire electrode 4 is added.
Let the processing be performed in a so-called immersed state such as in the working fluid.
Need to Further, in this processing step, the throttle valve 17i
It is enough to remain closed, and from the upper and lower nozzles 5c and 6c,
Flow rate adjusting valve 5 so that a relatively small amount of machining fluid is injected
e, 6e are adjusted. [0024] The following is a semi-finishing process using oil-based electric discharge machining liquid
Processing strips that are set to be switched in sequence for each process (second to fifth machining)
Describe and describe the matters. In addition, the processing of each of the following processing steps
The conditions are described in the above-mentioned first-cut setting processing rule.
Only the points that differ from the process or the processing process immediately before it are described.
It will be posted. (Second cut setting processing conditions) Processing fluid material Hydrocarbon oil (Class 4 third oil)
Kind) Density about 0.790 g / cm Flash point about 100 ° C. Kinematic viscosity about 2.2 cSt Supply pressure (up and down) 0.5 kgf each Nozzle discharge flow (up and down) 1 l / min Main power voltage pulse on time (τ _ON ) 1 μS Current amplitude (IP) 20 A Sub-source no-load voltage 100 V Voltage pulse on time (τ _on ) 0.5 μS Current amplitude (ip) 300 A Sub power supply (2) (Short-circuited when detecting the start of discharge in the gap
DC power supply with envelope breaker) Voltage 150V Short circuit current 0.3A Machining feed rate approx. 3 to 4mm / min Servo voltage (average machining voltage) approx. 110V Offset amount approx. 120μm
According to the above set machining conditions, the average machining current is about 0.4A.
Second-cut processing is performed at, and the surface roughness is about 15
-18 μm Rmax. In addition, this second
The machining process produces almost more accurate shapes and moreover the dimensions
It is the processing step of the production. (Processing conditions for third cut setting) Main power supply voltage pulse (τ _ON ) 1 μS Current amplitude (IP) 12A Sub power source no-load voltage 80V Voltage pulse on time (τ _on ) 0.2 μS Current amplitude (ip) 60 A Machining feed rate 5.5-6.5 mm / mi
n Servo voltage 115V Offset amount 110 μm (Setting conditions other than the above are the second cut processing described above.
According to the above set machining conditions, the average machining current is about 0.3A.
The third surface is cut with a rough surface of about 12-15
It became μmRmax. (Force cut setting processing conditions) Main power supply voltage pulse on time (τ _ON ) 0.5 μS Off time (τ _OFF ) 5.5 μS Current amplitude (IP) 12 A Machining feed rate 5.5 to 6.5 mm / mi
n Servo voltage 120V Offset amount 106μm (Setting conditions other than the above are the second cut process described above.
According to the above set machining conditions, the average machining current is about 0.2 A.
Fine electrical discharge machining is performed and the machined surface roughness is about 9 to 1
It became 2 μm Rmax. (Fifth Cut Setting Processing Condition) Main Power Supply Voltage Pulse Off Time (τ _OFF ) 3 μS Current amplitude (IP) 2.4 A Machining feed rate 7.5-8.5 mm / mi
n Servo voltage 115V Offset amount 103 μm (Other than the above, the setting processing conditions are the force cut processing described above.
According to the above set machining conditions, the average machining current is about 0.1 A.
Fine electric discharge machining is performed, and the surface roughness is about 7-9.
It became μmRmax. That is, the processed surface roughness μmRmax
However, it was almost certainly finished in the single digit range. In the conventional wire cut electric discharge machining method,
The final finishing process has been completed up to the fifth cut described above.
It was However, the above force cut and fifth cut
Prevent edge drooping multiple times, or
Surface roughness is further increased by repeating in a small range
Although an attempt was made to improve the surface roughness,
Since the fuzz value is small and the gap is small,
It is a very long processing that requires attention, and the processing surface
Is a fine matte surface, so light is used for surface roughness.
There are not so many, and what is called a mirror surface or mirror surface
Without, the mirror surface of the same surface roughness as the above surface roughness
Or, rather than a mirror surface type, a synthetic resin injection molding die is constructed.
If it is made, there is a defect that the molded product is not released from the mold well.
It was Therefore, the present invention is based on the above-mentioned Fifth
Roughness of the machined surface due to the finishing process until the cut
Suitable for workpieces that have been finished to a single digit of μmRmax
The final finishing process described below.
The desired mirror surface or mirror-like processing
To be achieved, for the above mentioned semi-finishing process
The working fluid supply device 17 of the
The machining fluid of each of the guides 5a of the guide block bodies 5 and 6,
6a and each of the power supply terminals 5b and 6b are provided on the cavity side.
Utilizing the circuit of the throttle valve 17i and the flow rate adjusting valve 17k for supplying
Then, the others are blocked or stopped, and the various types of
Elemental (Si), carbon (graphite, C), iron (Fe),
Aluminum (Al), copper (Cu), silicon carbide (Si
C), titanium carbide (TiC), titanium nitride (TiN),
Or silicon oxide (SiO _Two ), Etc., powder of about 5 μmφ
Average particle size of 0.1 μmφ or more
Is about several μmφ, 0.5% or less by weight percentage
The above hydrocarbon-based oil-based electric discharge machining liquid containing less than 5%
The processing liquid supply device 18 for storing and supplying is operated. The operating state of the supply device 18 is the same as the above-mentioned supply device.
It is almost the same as in the case of No. 17, but the powder is
Prevents their sedimentation and deposition as they are added and mixed
In order to avoid the
The device is provided in the clean liquid tank 18a. That
A stirring device such as this is used for final finishing in the processing tank 1.
In the case where the raising process is the dipping process described above,
Even for powder-mixed working fluid during processing and during collection
It is provided to prevent accumulation, etc.
The filter 18k between the cleaning liquid tank 18a and the cleaning liquid tank 18a is a mixed powder.
To selectively pass through or to collect the processing waste almost selectively.
Those having the function of being used are used. From the supplying device 18 to the supplying device 17, backwashing is performed.
Circuit for transferring the oil-based electric discharge machining fluid through the filter 18i
Is a guide from the throttle valve 17i and the flow rate adjusting valve 17k.
It is supplied to the cavity of the block bodies 5 and 6 and supplied.
Feeder 18 to guide block body 5. , 6 nozzles
The powder-containing oil-based electric discharge machining liquid supplied to 5c and 6c
Enter the cavity side and enter the guides 5a, 6a and the power supply.
Contamination or failure due to sticking, narrowing, etc. on 5b and 6b
It is supplied so that it does not exist, and this is the processing tank 1.
Supply from the drain of
It is provided so as to return to the polluted liquid tank 18b of the feeder 18.
At that time, the mixed powder is collected by the filter 18i.
Then, by operating the open / close valve 18k as appropriate, the collected powder can be removed from the clean liquid tank.
It is operated so as to return to 18a. Therefore, the powder-containing oil-based electric discharge machining liquid is appropriately used.
Each nozzle is filled with the processing tank 1 and agitated.
Forced to the machining gap from 5c and 6c along the wire electrode 4
Mirror surface or mirror-like finish
That the final finishing machining process for
Become. Fifth cut in the above-mentioned intermediate finishing process
The processed surface of the processed sample is further improved (about 7-9
μmRmax → 5 to 7 μmRmax)
Replenishment processing with oil-based electric discharge machining fluid mixed with powder as described
became. In addition, it is not described in the following set processing conditions.
The first condition is the above-mentioned first cut processing or second
It is the same as the cutting condition. (Replenishing processing 1) Machining fluid Immersion machining in oil-based electric discharge machining fluid Mixed powder Polycrystalline silicon average particle diameter of about 2-3 μm φ Addition amount 1.5 wt% Nozzle discharge flow rate (up and down) 0.5 l / min each Main power no-load voltage 80V Voltage pulse on time (τ _ON ) 0.5 μS Off time (τ _OFF ) 5 μS Current amplitude (IP) 12 A Sub power supply (2) (Voltage 150 V, short circuit current 0.3 A, direct connection with short circuit interruption described above)
Current supply) Machining feed rate Approx. 20 mm / min Servo voltage 80 V Offset amount About 110 μm Under the set machining conditions above, average machining voltage about 100 V
With a processing movement speed of about 6.5 mm / min, and an average processing voltage
Processing is performed at a flow of about 0.2 A, and supplementary processing (2)
As the above supplementary processing (1), the voltage pulse current of the main power source
Same setting condition except switching to amplitude (IP) = 4A
Then, the average processing voltage is about 120V, and the processing movement speed is about 7.2.
Processing at mm / min and average processing current of about 0.2A,
The processed surface roughness was finished to about 6 to 6.5 μRmax. With respect to the work piece subjected to the above supplementary processing,
Perform the final finishing process under the set processing conditions below, and
A glossy mirror-finished surface and a so-called mirror-finished surface were obtained.
In addition, the conditions not described in the set processing conditions described below
The conditions are the same as the conditions of the above-mentioned supplementary processing (1) or (2).
It (Mirror finishing 1st process setting condition) Main power supply voltage pulse Polarity: Positive polarity ON time (τ _ON ) 4.5 μS Off time (τ _OFF ) 0.5 μS Current amplitude (IP) 0.8 A Sub power supply (2) (DC power supply with short-circuit interruption) No load voltage 250 V Short-circuit current 0.5 A Machining feed rate approx. 20 mm / min Offset amount 145 μm or more Average processing voltage of about 210V, processing
Moving speed of about 7.2 mm / min, average machining current of about 0.2
Process A twice. Further, as a second step of mirror finishing, the above
Of the setting conditions of the 1st process, part of the main power-on time (τ _OFF ) 1.5 μS Current amplitude (IP) 2.4 A Machining feed rate Approximately 40 mm / min.
At 0 V, average machining current of about 0.2 A, machining movement speed of about 3
Processing is performed at 7 mm / min.
Repeat 10 times to obtain a glossy mirror surface.
I was able to. And the surface roughness is about 3.5 μmRm
It was ax. The second step of the final finishing step
The machining movement speed faster than the first process in
Maintains the shape accuracy of the upper and lower edges of the body and the convex corners of the machined surface
Is not an absolute requirement for mirror finishing.
The convex corner increases the machining speed before and after it.
By doing so, the machining movement speed is slower than the above, and
The desired mirror surface can be obtained with a small number of processing operations.
It seems possible. Further, the above-mentioned first step and second step and each processing
The number of workpieces to be processed in the multiple processing
If the plate thickness becomes larger than mm, the machined surface for mirror finishing
It is necessary to adjust the groundwork and process the entire plate thickness.
Therefore, on the contrary, the plate thickness is about 10 mm or so.
In the case of the following work piece of about several mm, once or several times
Can be made into the target mirror surface with a certain degree of processing
I knew that. In any case, the above-mentioned mirror-like processing is performed.
Each of the first and second steps of the final finishing process for processing
Seed setting processing conditions and processing control modes are
In the case of a lot of replenishment processing (1) and (2), or before that
For force and fifth cuts without powder mixing
In both cases, they are significantly different, and the difference is mirror-like
It is indispensable for processing. That is, the above
Average processing current (about 0.2A) in final mirror surface processing
And the preceding replenishment processing and force and fifth cut
Although it is close to the same value as that at the time of construction,
Looking at the pressure pulse, the on time of the pulse (τ _ON )
The former is about 10 times larger and the off time (τ _OFF ) Is the opposite
Is about 1/10 smaller than the
Kuta is as large as 90% and the current amplitude (IP) is small.
Has become. The no-load voltage applied to the gap is that of the main power supply.
Both are the same, but the one of the sub power source (2) is
Highly set and offset amount for replenishment processing and medium finishing
In the force and fifth cut of the barge, during non-discharge
The gap is about 3 to 10 μm.
However, in the case of the above experimental example, the gap during no discharge
When the setting is changed to a large value of about 45 μm
In both cases, the average voltage of the machining gap is about the above applied no-load voltage.
The feed is controlled so as to keep the value close to 85%, and the wire electrode
The discharge between the machined surface and the machined surface is not a direct discharge between the two.
Discharge through the powder that is dispersed and suspended in the working fluid.
As compared to the conventional finish pear surface
Mirror-like processing is possible. Further, according to the experiment of the present inventor,
Mirror finishing first step and second step of the final finishing step
In, switching the discharge circuit as described above
Inductance coil (20 wires of about 0.8 mmφ)
About 20μH, which is wound 10 times around a diameter of 250mmφ) in series
And processed under the same conditions as above.
The finished surface is a so-called glossy mirror surface, and the surface roughness is approximately
It became 2.5 μm Rmax. This is because the above-mentioned powder is obtained by inserting the coil.
The rise and break of the discharge current through the
If the shocking effect that acts on the machined surface is weakened,
At the time of life, multiple voltage pulses of the main power supply are connected.
Of the on-time
It acts like a short flashing discharge, concentrating on a local spot.
Instead, it spreads around it and moves horizontally
Probably due to the formation of a large basin-like discharge mark
Be seen. In addition, the above description and in the present specification,
A mirror surface and a mirror surface irradiate a laser beam parallel to the processed surface.
When the so-called reflectance is about 30% to about 50%, it is a mirror surface.
When it exceeds about 50%, it becomes about 70%
The case is called a mirror surface. The above-mentioned experimental example is the first cut processing
The most conventional pure water system in wire cut electrical discharge machining
Second finishing, such as second finishing, using the machining fluid of
Precision machining and calcination during wire cut electrical discharge machining
Used when processing cemented carbide such as WC-Co
Often used for hydrocarbon engraving and drilling EDM
Uses an oil-based processing liquid and shortens the processing time for the semi-finishing processing.
For finishing and facilitating the processing, the finishing process is finished.
As an example, a powder mixture obtained by adding and mixing powder to the above oil-based working fluid.
I tried to do replenishment processing using the compounding solution,
This semi-finishing process is like
The aspect of is significantly different from that of the previous process
Performed as a preparation for the final finishing process
Used in this semi-finishing process.
Even if an oil-based processing fluid is used throughout the entire process,
On the contrary, in order to improve processing efficiency, powder mixed oil is used throughout the entire process.
A system processing liquid may be used. Further, in order to make the processing simpler and more efficient,
Use pure water based processing fluid for all the above finishing steps.
Even so, by the processing of the final finishing process described above,
Although it is possible to obtain a mirror-finished surface by
Shape and final finishing process easy and reliable
As described above, the intermediate finishing process just before the final finishing process is performed.
At the end of the working process, the working process of 1-2 uses an oil-based working fluid,
It is better to finish the processed surface using oil-based processing liquid
It is. Also, prevention of electrolytic corrosion of the above cemented carbide
Depending on the processing purpose and other factors,
The oil-based processing liquid or powder-containing oil-based processing liquid is used from the
Of course, there are things to use. Then, a predetermined processing result in each processing step
The set offset amount for the contour line shape to be formed is
In the highest cutting process, usually the maximum value
Of course, it is set. And the offset amount
Is used in the intermediate finishing process such as second cut,
Normally smaller in sequence, and the next processing step is smaller than the previous processing step.
Even if they are set to be almost the same or the same
It is not set large, and the machined surface has a specified surface roughness and
And the dimensions are sequentially finished.
Since the gap length is not measured, the gap length is unknown
However, this is because powder-containing working fluid was used as the working fluid.
In some cases, it is necessary to use the four
Set larger than the case of the fist and cut
Although there is, it is processed for the purpose of finishing the surface roughness and dimensions.
It is almost the same as long as it is
Like the final finishing process for mirror-like processing,
Significantly larger offset than the previous semi-finishing process
It is considered that it has never been set. In the processing experiment of the present invention, the above-mentioned procedure was used.
Therefore, it is effective to insert an inductance coil into the discharge circuit.
However, this is a conventional wire power source for processing pulse power.
It was considered to be effective and necessary for the electrical discharge machining of about 0.
Short on-time of 5 to 5 μS and current as high as possible
Electrodes manufactured in consideration of sharp and high rising characteristics
Sections that may be due to the source being used
Therefore, the discharge current waveform, etc. can be changed significantly.
With a free pulsed power supply, such a large inductor
It may not be necessary to use a wire loop. But,
If the inductance loop has a rise or
It is a fact that it is effective for waveform control and prevention of discharge interruption.
Yes, and one more pulse power supply is attached, making it expensive.
Considering that, the reactance value can be set variably.
The use of an inductance coil that achieves its purpose simply by installing it
It is useful. The powder mixed in the oil-based processing liquid is
Crystalline silicon, SiC, SiO _Two , SiN _Four Silicon content such as
Powder seems to be the most preferable, but graphite and
Carbon powder, tungsten powder, iron or cast iron powder, aluminum
Minium powder can also form a mirror-finished surface to some extent.
It is possible because it can be used. The size of the powder
Is about 0.35 mmφ even if the wire electrode used is thick
Mainly those with a thickness of about 0.2 mmφ below
However, especially in precision machining, around 0.05 to 0.1 mmφ
From where to use the degree of
The use of powder causes the edges and corners to be consumed and the shape to collapse.
Therefore, even if it is large, it is smaller than 5 μmφ.
0.1 to 0.3 μmφ or more, preferably about 0.3 to 0.
Do not mix more than 5μmφ and about 1-2μmφ.
It seems that it is good to add and mix the amount of powder mixed with this kind of powder.
Almost the same as in the case of the working fluid, 0.3-5% by weight,
It is preferably about 0.5 to 3%. The electrical processing conditions include the average processing current.
Is the same value as in the case of conventional final finishing,
On time of voltage pulse (τ _ON ) Is significantly larger and
Off time (τ _OFF ) Is as long as the wire electrode is not broken
Set the value as small as possible, and
Due to the influence of the insertion of the inductance loop, multiple pulses are consecutive.
If a discharge close to a low current arc like
It seems to be there. And the gap (offset amount) is large
A high voltage is applied to the gap from where the setting is controlled.
Must be applied, but released through the entrained powder
Is more reliable, and the machined surface and wiper of the workpiece are
There is little direct discharge through the gap machining liquid between the electrode surfaces.
Powder by discharge through the powder rather than removing the surface
Of the mirror-like glossy surface by flight welding or alloying of the
It is thought to be forming. Also, processing control
As an example, the average machining voltage of the machining gap is
While maintaining a high value of about 80 to 90% of the load voltage
This needs to be done, but this is
Whether it is the result of engineering or the characteristics of the power supply, etc.
I'm not sure. Then, the setting of this final finishing process is added.
The type of work piece and the plate thickness depend on the working conditions and the control mode of processing.
It doesn't change much, and so
One or a small number of times for a thin work piece
While you can quickly finish to a mirror-like surface with,
For thick plates, the number of times increases almost proportionally.
It was confirmed that it was necessary to process it. Such a mirror surface or a mirror surface processing is straightforward.
Although not exactly the same, WC-Co sintered cemented carbide
It is also effective when applied to the processing. Below, the conditions of the book different from the above experimental example
The experimental examples of the invention are given below. [Experimental Example 2] Tungsten was used as the wire electrode and
Since the plate thickness of the processed body is thin, it is more oily than the first cut process.
Example of processing using a system-based processing liquid. Workpiece material SKD-61 Plate thickness 2.0 mm Wire electrode material Tungsten wire diameter 0.05 mm φ Applied tension 500 gf Renewal feed rate 4 m / min (Fast cut setting machining conditions) Machining fluid Oil-based electric discharge machining fluid Immersion machining nozzle diameter (up and down) ) 6mmφ Discharge flow rate (up and down) 6l / min each Main power source no-load voltage 80V Voltage pulse on time (τ _ON ) 2 μS Off time (τ _OFF ) 11 μS Current amplitude (IP) 2.4 A Sub power supply (2) (DC power supply with short circuit interruption) No load voltage 150 V Short circuit current 0.15 A Gap capacitor 0.01 μF Servo voltage 95 V Machining feed rate Imm / min Offset amount of 45 μm or more According to the set machining conditions, the average machining voltage is about 105
V, average machining current about 0.07A, machining movement speed 0.8m
It was processed at m / min. (Second cutting setting processing condition)
Only conditions different from the above first cut are described. Wire electrode renewal speed 6m / min Processing fluid properties Polycrystalline silicon powder added oil system processing
Addition amount of liquid powder 1.5% by weight Average particle size of added powder 2 μm φ Nozzle discharge flow rate (up and down) No jet (mixing of processing liquid in processing tank)
Stir) Main power supply voltage pulse on time (τ _ON ) 0.5 μS Off time (τ _OFF ) 5 μS Current amplitude (IP) 4 A Gap capacitor Not used Servo voltage 100 V Machining feed rate 20 mm / min According to the machining conditions set above, the average machining voltage is about 113
V, average processing current about 0.07A, processing movement speed about 7mm
/ Min processing. (Processing conditions for third cut setting)
Second cut Only different conditions will be described. Servo voltage 90V or more According to the set machining conditions, the average machining voltage is about 123V,
Average machining current of about 0.05A, machining movement speed of about 7.4m
Machining of m / min, the machined surface is about 5 μm Rmax
It's finished. (Conditions for mirror finish processing)
Only conditions that differ from Docut are described. Wire electrode update speed 4 mm / min Main power supply voltage pulse Polarity: Positive ON time (τ _ON ) 4.5 μS Off time (τ _OFF ) 1.5μS Current amplitude (IP) 2.4A Sub power supply (2) (DC power supply with short circuit interruption) No load voltage 250V Short circuit current 0.25A Servo voltage 200V Offset amount 70μm Average processing voltage approx. 240V,
Average machining current of about 0.05A, machining movement speed of about 7.2m
Surface treatment is performed at m / min.
Finished to a sufficiently glossy mirror surface, surface roughness of about 2.5 ~
It became 3 μm Rmax. [Experimental Example 3] (Example of processing a superalloy) Workpiece material WC-3% Co Plate thickness 50 mm Wire electrode material Brass wire diameter 0.2 mmφ Applied tension 1.28 kgf Renewal feed rate 6 m / min (first cut Setting processing conditions) Processing fluid material Pure water specific resistance 5 × 10 ^Four Ωcm Nozzle diameter (up and down) 6mmφ Discharge flow rate (up and down) 6l / min Main power supply no-load voltage 270V Voltage pulse on time (τ _ON ) 2.5 μS Off time (τ _OFF ) 6.5 μS Current amplitude (IP) 12 A Sub-source no-load voltage 270 V Voltage pulse on time (τ _on ) 0.5 μS (trailing edge of main pulse
Current amplitude (IP) 250A Servo voltage 33V Machining feed rate 7.5mm / min Offset amount 170μm According to the set machining conditions above, the average machining voltage is about 50V,
With an average processing current of about 4 A, processing movement speed of about 0.5 mm / m
It became in processing. (Second cutting setting processing conditions)
Only the conditions that are different from the above first cut setting processing conditions
Enter. Processing fluid properties Polycrystalline silicon powder added Oil-based additive
Addition amount of working fluid immersion processing powder 1.5% by weight Average particle size of added powder 2 μm φ Nozzle discharge flow rate (up and down) No jet flow (stirring of processing fluid in processing tank)
Stir) Main power supply voltage pulse No load voltage 120V Off time (τ _OFF ) 11 μS Sub power supply voltage pulse current amplitude (ip) 200 A Sub power supply (2) (DC power supply with short circuit interruption) No load voltage 150 V Short circuit current 0.15 A Servo voltage 75 V Machining feed rate 20 mm / min Offset amount 112 μm or more Machining conditions According to the average processing voltage of about 85V,
With an average processing current of about 0.7 A, processing movement speed of about 2.6 mm
/ Min processing. (Processing conditions for third cut setting)
Only the conditions that differ from the processing conditions set for the second cut are described.
To do. Main power supply voltage pulse on time (τ _ON ) 2 μS Off time (τ _OFF ) 5.5 μS Servo voltage 90 V Offset amount 110 μm Under the set processing conditions above, the average processing voltage is about 100
V, average machining current of about 0.4 A, machining movement speed of about 6 mm
/ Min processing. (Force cutting setting processing conditions)
Only the conditions that are different from the above third cut setting processing conditions are described.
To do. Main power no-load voltage 100V Voltage pulse on time (τ _ON ) 1 μS Off time (τ _OFF ) 5μS offset amount 110μm or more, under the set processing conditions, average processing voltage about 100V, average
Processing current of about 0.2A, processing movement speed of about 6mm / min
It was processed. (Fifth cut setting processing conditions)
Only conditions that differ from the above-mentioned force cut setting processing conditions are described.
List. Main power no-load voltage 80V Voltage pulse on time (τ _ON ) 0.5 μS offset amount 110 μm or more The processing state under the set processing conditions is the above-mentioned forming condition.
It was almost the same as the case of scut processing. (Six cut setting processing conditions)
Only the conditions that differ from the above Fifth Cut setting processing conditions are described.
List. Main power supply voltage Pulse current amplitude (IP) 4A Sub power supply Only sub power supply (2) is used Offset amount 110 μm According to the set machining conditions, the average machining voltage is about 103
V, average machining current of about 0.06 A, machining movement speed of about 7 m
Machining of m / min, surface roughness is about 4.5 μmR
It was finished to max. (Conditions for mirror finish processing)
Only the conditions that differ from the scut setting processing conditions are described. Main power voltage pulse Polarity: Positive ON time (τ _ON ) 4.5 μS Off time (τ _OFF ) 0.5μS Sub power supply (2) (DC power supply with short circuit interruption) No load voltage 250V Short circuit current 0.5A Insertion inductance coil 20μH (series in discharge circuit)
Inserted into the offset) According to the setting processing condition of offset amount 150 μm or more, the average processing voltage is about 220
V, average machining current of about 0.2 A, machining movement speed of about 7.2
mm / min machining, and this machining is 3
By repeating the process, the processed surface is finished into a mirror-like glossy surface.
The surface roughness was about 3.5 μmRmx. As described above, in the processing method of the present invention
The setting processing conditions for mirror finishing in the final finishing process are
Except for some control conditions, especially for electrical voltage pulse
On time (τ _ON ), Off time (τ _OFF ), And that
Duty factor and discharge of voltage pulse according to selected setting
Viewed from the current amplitude (IP), mainly using the standard electrode
There is no consumption of electrodes in normal engraving and perforation electric discharge machining
Approximately the set machining conditions for the low-wear finishing machining area
Therefore, the mirror finishing process of each of the above-mentioned experimental examples was applied to the voltage application electrode.
In the case of reverse polarity processing that switched only the property, it is a mirror surface
Although it is close to
It was thought that it was necessary to further search the work conditions. As described in detail above, the wire cable of the present invention is used.
According to the conventional electric discharge machining method,
Approximately 4 to 6 μm R with constant dimensional accuracy and processed surface roughness in the single digit range
For the machining surface finished to max, use oil as a machining fluid.
Finishing powder-mixed EDM using a system EDM
When applying as processing, if you set specific processing conditions
In both cases, the processing is performed in the processing state of the specific mode.
The surface to be machined does not have the same level of roughness in a short time.
Improves and finishes to a mirror-like or mirror-like glossy surface
Processing that can be done and does not require time-consuming polishing
Can be processed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of an embodiment of an apparatus for performing wire cut electric discharge machining of the present invention. [Explanation of reference numerals] 1 processing tank 2 cross table 3 workpiece 4 wire electrodes 5, 6 upper and lower guide block bodies 5a, 6a upper and lower positioning guides 5b, 5c upper and lower nozzles 5d, 6d partition walls 7, 8 X, Y Axis drive motor 9 Main machining power supply 10 Sub power supply 11 Switching device 12 Control device 13 Power supply switching means 14 Inductance coil 15 NC control devices 16, 17, 18 Working fluid supply control device 19 Working fluid switching control means 20 Processing state detection device

Claims (1)

Claim: What is claimed is: 1. A wire electrode stretched in a predetermined state between a pair of guides arranged at intervals is renewed in the axial direction and is moved while being processed from a direction substantially perpendicular to the axial direction. The bodies are made to face each other through a minute gap, and machining is performed by an electric discharge pulse generated by applying an intermittent voltage pulse between the two in a state in which a machining liquid is supplied to the gap and interposes the wire electrode and the workpiece. In the wire-cut electric discharge machining which gives a relative machining feed along a predetermined contour line shape to be machined on the plane in the perpendicular direction, the wire-cut electric discharge machining, the material of the workpiece to be machined, the plate thickness , And a first cut for forming a first machining groove on the workpiece along a locus offset by a predetermined amount from the predetermined contour line under the processing conditions selected and set according to the purpose of the processing, etc. After the first cutting process and the machining process, the set conditions are sequentially switched to the machining conditions of one or more machining processes such as a predetermined second cut and a third cut, and the machined surface roughness of the machined surface of the workpiece is sequentially switched. The oil is mixed with powder, which is a finishing fluid processing step in which the processing steps are sequentially performed until the degree reaches a smaller predetermined value, and the processing conditions are switched to the predetermined processing conditions, and the processing liquid supplied to the processing gap is interposed. Switching to a system working liquid, and further setting the offset value of the wire electrode relative to the predetermined contour line shape by increasing the offset value by a predetermined amount from the offset value in the final processing step of the previous semi-finishing processing step,
The wire-cutting discharge, which comprises a final finishing machining step in which machining feed is controlled so that the machining gap average voltage during machining is sufficiently higher than that in the previous intermediate finishing machining step. Processing method. 2. In the first-cut machining step, a pure water-based machining fluid is used as a machining fluid supplied to the machining gap, and the machining fluid after the intermediate finishing machining step is switched to an oil-based machining fluid. The wire-cut electric discharge machining method according to claim 1, wherein the wire-cut electric discharge machining method is performed. 4. The wire cut discharge according to claim 1, 2 or 3, wherein in the semi-finishing step, the working fluid to be supplied and intervened in the working gap is an oil-based working fluid mixed with powder. Processing method. 5. A relative offset value with respect to the predetermined contour line shape between the wire electrode and the workpiece in the successive machining steps of the semi-finishing machining step is sequentially set to be small or substantially the same every switching of machining conditions. The wire-cut electric discharge machining method according to claim 1 or 2, wherein the sequential machining steps are performed. 5. The discharge circuit is switched so that the inductance of a predetermined value is inserted in series in the voltage pulse application discharge circuit in the final finishing step, so that the discharge circuit is processed. 3. The wire cut electric discharge machining method according to 3 or 4. 6. The silicon-based electric discharge machining fluid used by switching in the final finishing step is a hydrocarbon electric discharge machining fluid having a particle size of less than 5 μmφ and an average particle size of 0.1 μmφ or more. The wire cut electric discharge machining method according to claim 1, wherein the powder contains 0.5% or more and less than 5% by weight. 7. The plate thickness of the object to be processed is cutting in the final finishing step, in which at least two or more steps are fed along the increased offset trajectory along the predetermined processing contour line shape. 7. The wire cut electric discharge machining method according to claim 1, wherein the number of machining steps is increased according to the above. 8. The set no-load voltage of the gap applied voltage pulse is set to a value sufficiently higher than the set no-load voltage in the previous semi-finishing working step during the set working conditions in the final finishing working step. Claims 1, 2,
The wire-cut electric discharge machining method according to 3, 4, 5, 6 or 7. 9. Under the set machining conditions in the final finishing step, the pulse width of the gap applied voltage pulse is set to be larger than the pulse width in the final finishing step of the intermediate finishing step, and the duty factor is set to 6.
The wire-cut electric discharge machining method according to claim 1, wherein the machining is performed by selecting 0% or more and 95% or less. 10. The control of the machining feed in the final finishing machining step is controlled so that the average voltage of the machining gap is maintained at 70% or more of the no-load voltage of the gap applied voltage, and about 80 to 90%. The wire-cut electric discharge machining method according to claim 1, 2, 3, 4, 5, 6, 7, or 8.