CN113710398A

CN113710398A - Wire electric discharge machining apparatus

Info

Publication number: CN113710398A
Application number: CN201980095387.4A
Authority: CN
Inventors: 中泽瞬; 汤泽隆; 大友阳一; 中里茂行
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2019-04-18
Filing date: 2019-04-18
Publication date: 2021-11-26
Anticipated expiration: 2039-04-18
Also published as: JPWO2020213112A1; WO2020213112A1; JP6647469B1; CN113710398B

Abstract

A wire electric discharge machining device (1) is provided with: a workpiece holder (50) for holding columnar ingots (30a, 30b) in parallel in the same plane; a wire electrode (12) that is arranged linearly so as to face the ingots (30a, 30b) and that performs wire discharge machining on the ingots (30a, 30b) at positions facing the ingots (30a, 30 b); and a pair of processing liquid supply hoses (20a, 20b) which are arranged at positions along the linear electrode (12) and are opposed to each other with the ingots (30a, 30b) therebetween, wherein the processing liquid (70) is sprayed onto the ingots (30a, 30b) along the linear electrode (12), the ingots (30a, 30b) have the same diameter, and the workpiece holder (50) holds the ingots (30a, 30b) so that the interval between the cylindrical shafts (35a, 35b) of 2 ingots (30a, 30b) is 1.2D or more and 2D or less, when the diameter is D.

Description

Wire electric discharge machining apparatus

Technical Field

The present invention relates to a wire electric discharge machining apparatus for simultaneously wire electric discharge machining a plurality of ingots by 1 wire.

Background

One of the wire electric discharge machining apparatuses is an apparatus in which 2 ingots as a workpiece are arranged in parallel, and the wire electric discharge machining is simultaneously performed on the 2 ingots by 1 wire. In the wire electric discharge machining apparatus described in patent document 1, a plurality of wire cutting portions are formed by winding 1 wire electrode between 4 guide rollers and arranging them in parallel, and power is supplied to each wire cutting portion individually. The wire electric discharge machining apparatus simultaneously discharges between each wire cutting portion and the ingot while supplying the machining liquid to each wire cutting portion, thereby simultaneously cutting 2 ingots and cutting each ingot into a plurality of pieces at a time.

Patent document 1: japanese laid-open patent publication (Kokai) No. 2015-47685

Disclosure of Invention

However, in the technique of patent document 1, when the distance between the centers of 2 ingots is too small, the machining liquid supplied to one ingot collides with the machining liquid supplied to the other ingot, and the machining liquid may stagnate inside the machining tank of each ingot, thereby preventing removal of cutting chips. Further, when the interval between the centers of 2 ingots is too wide, the wire vibration during the machining becomes large, and the precision of the cutting process may be lowered.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wire electric discharge machining apparatus capable of performing highly accurate cutting machining while preventing machining liquids supplied to adjacent ingots from colliding with each other even when a plurality of ingots arranged in parallel are simultaneously wire-electric discharge machined through 1 wire.

In order to solve the above problems and achieve the object, a wire electric discharge machining apparatus according to the present invention includes: a holding unit for holding a cylindrical 1 st workpiece and a cylindrical 2 nd workpiece arranged in parallel in the same plane; and wire electrodes that are linearly arranged so as to face the 1 st workpiece and the 2 nd workpiece, respectively, and that perform wire discharge machining on the 1 st workpiece and the 2 nd workpiece at positions facing the 1 st workpiece and the 2 nd workpiece. The wire electric discharge machining apparatus of the present invention includes a pair of machining liquid supply portions disposed at positions along the wire electrode and facing each other with the 1 st workpiece and the 2 nd workpiece interposed therebetween, and configured to spray machining liquid onto the 1 st workpiece and the 2 nd workpiece along the wire electrode, wherein the 1 st workpiece and the 2 nd workpiece have the same diameter, and the holding portion holds the 1 st workpiece and the 2 nd workpiece such that an interval between a cylindrical axis of the 1 st workpiece and a cylindrical axis of the 2 nd workpiece is 1.2D or more and 2D or less, when the diameter is D.

ADVANTAGEOUS EFFECTS OF INVENTION

The wire electric discharge machining apparatus according to the present invention has an effect of suppressing collision of machining liquids supplied to adjacent ingots and performing high-precision cutting even when a plurality of ingots arranged in parallel are simultaneously wire-electric discharge machined through 1 wire.

Drawings

Fig. 1 is a diagram showing a configuration of a wire electric discharge machine according to an embodiment.

Fig. 2 is a diagram for explaining the arrangement position of an ingot processed by the wire electric discharge machine according to the embodiment.

Fig. 3 is a diagram illustrating a processing tank for an ingot processed by the wire electric discharge processing apparatus according to the embodiment.

Fig. 4 is a diagram for explaining the flow of the machining liquid ejected from the nozzle of the wire electric discharge machining apparatus according to the embodiment.

Fig. 5 is a diagram for explaining a numerical analysis model of the arrangement position of the ingot in the wire electric discharge machine according to the embodiment.

Fig. 6 is a diagram for explaining an analysis result of numerical analysis performed on the wire electric discharge machine according to the embodiment.

Fig. 7 is a diagram showing a calculation result in the case where the amplitude of the wire electrode is calculated using a logical expression for the wire electric discharge machining device according to the embodiment.

Detailed Description

Next, a wire electric discharge machine according to an embodiment will be described in detail with reference to the drawings. The present invention is not limited to the embodiments.

Provided is an implementation mode.

Fig. 1 is a diagram showing a configuration of a wire electric discharge machine according to an embodiment. In fig. 1, the lateral direction in the paper plane is the X direction, the upward direction in the paper plane is the Z direction, and the proximal direction with respect to the paper plane is the Y direction. The Z direction is a direction opposite to the vertical direction, and the XY plane is a horizontal plane. Fig. 2 is a diagram for explaining the arrangement position of an ingot processed by the wire electric discharge machine according to the embodiment. Fig. 2 shows a cross-sectional view of the

ingots

30a and 30b when the

ingots

30a and 30b are viewed from the Y direction.

The wire electric discharge machine 1 is a machine that wire electric discharge machines a plurality of ingots simultaneously with 1 wire. In the present embodiment, a case will be described in which the wire electric discharge machining apparatus 1 wire-electric-discharge-machines 2

ingots

30a and 30b simultaneously by 1 wire.

When the diameter of the

columnar ingot

30a, 30b is D, the wire electric discharge machining apparatus 1 performs cutting in a state where the

ingot

30a, 30b is disposed so that the distance Xd between tangent lines Ta, Tb perpendicular to the wire electrode 12 of 2

ingots

30a, 30b becomes an interval of 0.2D or more and 1D or less. The tangent line Ta is a vertical tangent line on the side closer to the ingot 30b, among tangent lines perpendicular to the wire electrode 12 of the ingot 30a, and the tangent line Tb is a vertical tangent line on the side closer to the ingot 30a, among tangent lines perpendicular to the wire electrode 12 of the ingot 30 b. That is, the shortest distance Xd (distance in the X direction) between the

ingots

30a, 30b is a distance of 0.2D or more and 1D or less. In other words, the wire electric discharge machine 1 has a pitch of centers having the same Y coordinate among the centers of circles included in the

ingots

30a and 30b of 1.2D or more and 2D or less. The circle of the ingot 30a and the circle of the ingot 30b in this case are circles in the same XZ plane. That is, the distance between cylindrical axis 35a of ingot 30a and cylindrical axis 35b of ingot 30b is 1.2D or more and 2D or less. The columnar axis 35a is an axis passing through the center of the top surface and the center of the bottom surface of the columnar ingot 30a, and the columnar axis 35b is an axis passing through the center of the top surface and the center of the bottom surface of the columnar ingot 30 b. That is, columnar axis 35a is an axis parallel to a generatrix of ingot 30a (an axis extending in the height direction of ingot 30 a), and columnar axis 35b is an axis parallel to a generatrix of ingot 30b (an axis extending in the height direction of ingot 30 b). As a result, as will be described later, collision of the

jets

71a and 71b of the working fluid 70 supplied from both sides of the

ingots

30a and 30b is suppressed, stagnation of the working fluid 70 is prevented from occurring in the processing tanks of the

ingots

30a and 30b, and the precision of the cutting process is maintained.

The wire electric discharge machining apparatus 1 includes a wire feeding bobbin 11, a wire electrode 12,

winding guide rollers

13a, 13b, 13c, 13d, a winding bobbin 14,

positioning guide rollers

15a, 15b,

power feeders

17a, 17b,

nozzles

19a, 19b, machining

liquid supply hoses

20a, 20b, a machining table 40, a workpiece holder 50, and a machining tank 60.

In the wire electric discharge machine 1, a workpiece holder 50 for holding the

ingots

30a and 30b is disposed on a table 40 in a processing tank 60, and the processing tank 60 is filled with a processing liquid 70. An example of the wire electric discharge machine 1 is a multi-wire electric discharge machine.

The extraction bobbin 11, the wire electrode 12, the

winding guide rollers

13a, 13b, 13c, 13d, the winding bobbin 14, and the

positioning guide rollers

15a, 15b are formed of columnar members extending in the Y direction. The wire electrode 12 is drawn out by the drawing bobbin 11, the wire electrode 12 is wound around the winding guide rollers 13a to 13d, and the wire electrode 12 is wound around the winding bobbin 14. The

positioning guide rollers

15a and 15b perform positioning of the wire electrode 12.

In the wire electric discharge machining apparatus 1 according to the present embodiment, 1 wire electrode 12 drawn from the drawing bobbin 11 is sequentially wound at a plurality of intervals of a minute pitch between the plurality of

winding guide rollers

13a, 13d, 13c, and 13 b. In other words, 1 wire electrode 12 is wound around each of the winding guide rollers 13a to 13d in sequence, and the wire electrodes 12 are arranged in parallel with the axial direction (X direction) of the wire electrode 12. The portions of the wire electrode 12 that cut the

ingots

30a, 30b (portions facing the

ingots

30a, 30b) are wire cutting portions.

That is, the wire electrode 12 forms a plurality of wire cutting portions. The plurality of wire cutting portions are provided in parallel with a space apart from each other, and face the

ingots

30a and 30b, respectively. The interval between the wire cutting portions formed by winding the wire electrode 12 is the processing width of the

ingots

30a and 30b, that is, the thickness of the cut workpiece (thin plate cut from the

ingots

30a and 30 b). As described above, the wire electrode 12 is linearly arranged so as to face the

ingots

30a and 30b, respectively, and wire discharge machining is performed on the

ingots

30a and 30b at positions facing the

ingots

30a and 30 b.

The wire electric discharge machining apparatus 1 is configured such that the wire cutting portion is disposed opposite the

ingots

30a, 30b with a predetermined interval therebetween in a state where the wire electrode 12, the

winding guide rollers

13c, 13d, the winding bobbin 14, the

positioning guide rollers

15a, 15b, the

power feeding members

17a, 17b, the

nozzles

19a, 19b, the machining

liquid supply hoses

20a, 20b, the machining table 40, the workpiece holder 50, and the

ingots

30a, 30b are immersed in the machining tank 60 filled with the machining liquid 70, and a voltage is applied between the wire cutting portion and the

ingots

30a, 30 b. The wire electric discharge machining apparatus 1 performs machining feed of the

ingots

30a and 30b in the cutting direction with respect to the wire cutting portion, thereby cutting the

ingots

30a and 30b by electric discharge through the wire cutting portion. That is, the wire electric discharge machining apparatus 1 includes a drive mechanism (not shown) that relatively machines and feeds the wire electrode 12 and the

ingots

30a and 30b held by the workpiece holder 50. Thereby, the

ingots

30a and 30b are simultaneously processed into a plurality of thin plates.

The

ingots

30a and 30b as the work pieces are columnar having the same diameter, and are columnar in the present embodiment. The

ingots

30a and 30b are held in parallel by the workpiece holders 50 in the processing tank 60 so that the Y direction is the axial direction. The

ingots

30a, 30b are material to be cut into a plurality of thin sheets. The

ingots

30a and 30b may be, for example, a metal such as tungsten or molybdenum to be a sputtering target, or may be a ceramic such as polycrystalline silicon carbide used as various structural members. The

ingots

30a and 30b may be monocrystalline silicon to be semiconductor device wafers, semiconductor materials such as monocrystalline silicon carbide and gallium nitride, or solar cell materials such as monocrystalline silicon and polycrystalline silicon to be solar cell wafers.

Fig. 1 shows a case where 1 wire electrode 12 is wound around the plurality of winding

guide rollers

13a, 13b, 13c, and 13d, but the present invention is not limited to this case. That is, if a plurality of wire cutting portions can be formed by folding back 1 wire electrode 12, the specific configuration thereof is not particularly limited. The wire cutting portion may be 1 portion in each of the

ingots

30a and 30 b.

In the present embodiment, the plurality of winding

guide rollers

13a, 13b, 13c, and 13d are cylindrical and are disposed so as to be separated from each other so as to be parallel to each other in the Y direction perpendicular to the direction (X direction) in which the respective axes extend. In the present embodiment, 4 winding guide rollers 13a to 13d are arranged, but the number of the winding guide rollers 13a to 13d may be 2, 3, or 5 or more. In the following description, when the 4 winding guide rollers 13a to 13d are divided, they are referred to as "1 st winding guide roller 13 a", "2 nd winding guide roller 13 b", "3 rd winding guide roller 13 c", and "4 th winding guide roller 13 d", respectively.

The 1 st winding guide roller 13a and the 2 nd winding guide roller 13b are provided at positions higher than the 3 rd winding guide roller 13c and the 4 th winding guide roller 13 d. The 3 rd winding guide roller 13c and the 4 th winding guide roller 13d are arranged at a position higher than the

ingots

30a and 30b and lower than the 1 st winding guide roller 13a and the 2 nd winding guide roller 13 b.

The wire electrode 12 drawn out from the drawing bobbin 11 is wound around the winding bobbin 14 after being wound between the 1 st to 4 th winding guide rollers 13a to 13d a predetermined number of times.

As shown in fig. 1, the wire electrode 12 is a wire portion R between the 3 rd winding guide roller 13c and the 4 th winding guide roller 13d as a wire cutting portion, and can be disposed to face the

ingots

30a, 30 b. In the wire electric discharge machining apparatus 1, the

ingots

30a and 30b are opposed to the wire cutting portion with a minute gap therebetween, and electric discharge machining is performed.

A plurality of

positioning guide rollers

15a and 15b for suppressing vibration of the wire electrode 12 are disposed between the wire cutting section and the 3 rd winding guide roller 13c and between the wire cutting section and the 4 th winding guide roller 13d, respectively. In the following description, the 2

positioning guide rollers

15a and 15b are referred to as "1 st positioning guide roller 15 a" and "2 nd positioning guide roller 15 b", respectively.

The 1 st registration guide roller 15a is provided between the wire cutting section and the 3 rd winding guide roller 13 c. The 1 st positioning guide roller 15a is disposed apart from the 3 rd winding guide roller 13c so that the axial direction of the 1 st positioning guide roller 15a is parallel to the axial direction of the 3 rd winding guide roller 13 c.

The 2 nd registration guide roller 15b is provided between the wire cutting section and the 4 th winding guide roller 13 d. The 2 nd positioning guide roller 15b is disposed apart from the 4 th winding guide roller 13d so that the axial direction of the 2 nd positioning guide roller 15b and the axial direction of the 4 th winding guide roller 13d are parallel to each other.

As described above, the wire electrode 12 is wound around the winding guide rollers 13a to 13d so as to sequentially contact the extraction bobbin 11, the winding guide roller 13a, the winding guide roller 13d, the feeder 17b, the positioning guide roller 15a, the feeder 17a, the winding guide roller 13c, the winding guide roller 13b, and the winding bobbin 14.

The power feeding unit 17a is disposed between the 3 rd winding guide roller 13c and the 1 st registration guide roller 15a, and the power feeding unit 17b is disposed between the 4 th winding guide roller 13d and the 2 nd registration guide roller 15 b.

The wire electrode 12 is a power feeding wire to which a machining voltage for performing electric discharge machining is applied and to which a current is supplied, at a portion between the 3 rd winding guide roller 13c and the 1 st positioning guide roller 15a and at a portion between the 4 th winding guide roller 13d and the 2 nd positioning guide roller 15 b.

A pulse-shaped machining voltage (high-frequency pulse power) for performing electric discharge machining is applied to the power feeding line portion of the wire electrode 12 from a machining power source (not shown) via the

power feeders

17a and 17b, and a current is supplied thereto. Thereby, a machining voltage is applied between the wire cutting portion and the

ingots

30a and 30 b.

The

power feeders

17a and 17b are provided in accordance with the number of wire cutting sections formed by the wire electrode 12. The plurality of

power feeding elements

17a and 17b are insulated from each other and arranged in a row on both sides of the

ingots

30a and 30b, thereby constituting a power feeding element unit.

The power feeder disposed between the 3 rd winding guide roller 13c and the 1 st registration guide roller 15a is a power feeder 17a, and a power feeder group composed of power feeders 17a arranged in the Y direction is a 1 st power feeder unit. The power feeder disposed between the 4 th winding guide roller 13d and the 2 nd positioning guide roller 15b is a power feeder 17b, and a power feeder group including the power feeders 17b arranged in the Y direction is a 2 nd power feeder unit.

The wire electric discharge machine 1 is configured such that a voltage can be independently applied to each wire cutting portion by each of the

power feeding devices

17a and 17 b. A plurality of machining power supply units capable of independently applying a voltage to the parallel wire cutting sections are connected to a control device, not shown, of the wire electric discharge machining apparatus 1. The machining power supply unit applies a voltage to the corresponding wire cutting portion via the corresponding

power feeding members

17a and 17b in accordance with an instruction from the control device. The polarity of the voltage applied to the wire electric discharge machine 1 of the present embodiment can be appropriately reversed as necessary, as in the case of the conventional wire electric discharge machine.

A part of the wire R between the 1 st positioning guide roller 15a and the 2 nd positioning guide roller 15b in the wire electrode 12 becomes a wire cutting section. The pair of

nozzles

19a and 19b are machining liquid supply portions for spraying the machining liquid 70 to the

ingots

30a and 30b along the linear line portions R. The nozzle 19a is disposed between the 1 st positioning guide roller 15a and the ingot 30a, and the nozzle 19b is disposed between the 2 nd positioning guide roller 15b and the ingot 30 b.

A working fluid supply hose 20a is connected to the nozzle 19a, and a working fluid supply hose 20b is connected to the nozzle 19 b. The nozzle 19a removes machining chips of the ingot 30a by spraying the machining liquid 70 to the ingot 30a along the line portion R, and the nozzle 19b removes machining chips of the ingot 30b by spraying the machining liquid 70 to the ingot 30b along the line portion R. The

nozzles

19a, 19b are made of an electrically insulating material, or are subjected to an electrically insulating treatment such as aluminum anodizing treatment so as to be in contact with the wire electrode 12 without short-circuiting.

The machining liquid 70 flowing into the

nozzles

19a and 19b from the machining

liquid supply hoses

20a and 20b is discharged to the outside of the

nozzles

19a and 19b at the position of the line portion R. A machining tank for performing wire electric discharge machining is present in a direction in which the machining liquid 70 is discharged from the

nozzles

19a and 19b, and the machining liquid 70 enters the inside of the machining tank. The working fluid 70 supplied to the inside of the processing tank is discharged into the space between the

ingots

30a and 30b while removing the machining chips in the inside of the processing tank.

The

ingots

30a and 30b are held by the workpiece holder 50 so that the axial direction thereof is the Y direction. That is, the workpiece holder 50 as a holding portion holds the

ingots

30a and 30b in parallel in the same plane. At this time, when the diameter of the

ingot

30a, 30b is set to the diameter D, the workpiece holder 50 fixes the

ingot

30a, 30b by setting a distance Xd between tangent lines Ta, Tb perpendicular to the wire electrode 12 of 2

ingots

30a, 30b between the

ingots

30a, 30b to be a distance of 0.2D or more and 1D or less.

The

ingots

30a and 30b are controlled in position by a position control device, not shown, so as to be spaced apart from the wire electrode 12 wound between the 1 st to 4 th winding guide rollers 13a to 13d by a minute gap. By this control, an appropriate discharge gap length is maintained.

Fig. 3 is a diagram illustrating a processing tank for an ingot processed by the wire electric discharge processing apparatus according to the embodiment. Fig. 4 is a diagram for explaining the flow of the machining liquid ejected from the nozzle of the wire electric discharge machining apparatus according to the embodiment. In fig. 3, the lateral direction in the paper plane is the X direction, the downward direction in the paper plane is the Y direction, and the proximal direction to the paper plane is the Z direction. The distal direction of the paper surface is the vertical direction, and the XY plane is the horizontal plane. By the electric discharge machining, the machined grooves C having a width of about several μm to several tens μm larger than the diameter D of the line portion R shown in fig. 3 are formed in the

ingots

30a, 30 b.

According to the configuration described above, as shown in fig. 4, the

jets

71a and 71b of the working fluid 70 are simultaneously jetted from the

nozzles

19a and 19b provided on both sides of the

ingots

30a and 30b, and the

jets

71a and 71b pass through the inside of the working groove C along the linear line portion R and are jetted from the inside of the working groove C along the line portion R. Here, if the

jets

71a and 71b of the machining liquid 70 collide with each other at the collision point P on the same axis as the

nozzles

19a and 19b, a flow is formed in the vicinity of the collision point P such that the

jets

71a and 71b spread around the collision point P. In this case, since the 2

ingots

30a and 30b are fixed while being separated so that the distance Xd between the tangent lines Ta and Tb perpendicular to the wire electrode 12 becomes Xd ≧ 0.2D, it is possible to suppress a decrease in the flow velocity of the

jets

71a and 71b of the machining liquid 70 flowing through the inside of the machining tank C due to the stagnation of the machining liquid 70 occurring in the vicinity of the collision point P. This can suppress stagnation of

jets

71a and 71b of machining liquid 70 in machining tank C. Therefore, the momentum of the

jets

71a and 71b of the machining liquid 70 ejected toward the machining grooves C of the

ingots

30a and 30b is maintained inside the machining grooves C, and therefore the

jets

71a and 71b of the ejected machining liquid 70 can remove machining chips inside the machining grooves C while maintaining a sufficient flow velocity. Further, since the distance Xd between the tangent lines Ta and Tb perpendicular to the wire electrode 12 of the 2

ingots

30a and 30b is fixed so that Xd is not more than 1D, it is possible to suppress an increase in the amplitude of the wire vibration during machining and maintain the accuracy of the cutting machining.

Next, the reason why the distance Xd between the tangent lines Ta, Tb perpendicular to the wire electrode 12 of the 2

ingots

30a, 30b is set to 0.2D or more and 1D or less will be described. A3-dimensional model of an ingot having a plate thickness of 3mm and a diameter of 50mm after cutting and a 3-dimensional model of an ingot having a plate thickness of 3mm and a diameter of 100mm after cutting were prepared, and changes in the flow of a processing liquid in a processing tank due to the installation intervals of the ingots were investigated by numerical analysis using 2 3-dimensional models of ingots.

Fig. 5 is a diagram for explaining a numerical analysis model of the arrangement position of the ingot in the wire electric discharge machine according to the embodiment. Fig. 5 shows an ingot mold in a case where the

ingots

30a and 30b are viewed from the Y direction. Next, an outline of a numerical analysis model for analyzing the arrangement position of the ingot model and boundary conditions of the arrangement positions of the

ingots

30a and 30b will be described.

The 1 st ingot mold was the 3D mold of the aforementioned ingot having a plate thickness of 3mm and a diameter of 50mm, and the 2 nd ingot mold was the 3D mold of the aforementioned ingot having a plate thickness of 3mm and a diameter of 100 mm.

The working fluid 70 was water and a standard k-epsilon model was used for the turbulence model. The flow rate of the processing liquid 70 discharged from the

nozzles

19a and 19b was set to 10L/min for an ingot having a diameter of 50mm and 20L/min for an ingot having a diameter of 100 mm. Since the state in which the groove width was 0.15mm and the cutting was 80% was simulated in the analysis, the groove depth F was 40mm in the 1 st ingot model (3D model of ingot in the case where the diameter of the

ingots

30a and 30b was 50 mm) and 80mm in the 2 nd ingot model (3D model of ingot in the case where the diameter of the

ingots

30a and 30b was 100 mm). The change in the flow of the processing liquid in the processing tank when the installation interval of the

ingots

30a and 30b, that is, the distance Xd between the tangent lines Ta and Tb perpendicular to the wire electrode 12 was changed was verified by the 1 st ingot model and the 2 nd ingot model.

In fig. 5, the position at which the flow rate of the machining liquid 70 is measured is shown by the position 90. In the following description, the

ingots

30a and 30b having a diameter of 50mm may be referred to as a 1 st ingot group, and the

ingots

30a and 30b having a diameter of 100mm may be referred to as a 2 nd ingot group.

Fig. 6 is a diagram for explaining an analysis result of numerical analysis performed on the wire electric discharge machine according to the embodiment. In fig. 5, a relationship between the value Z and the flow velocity is plotted with the value Z obtained by normalizing the distance Xd between the tangent lines Ta and Tb perpendicular to the wire electrode 12 by the diameter D of the

ingots

30a and 30b as the horizontal axis and the flow velocity near the outlet of the processing tank (position 90) as the vertical axis. In fig. 6, a circular-shaped mark 41 shows the relationship between the value Z and the flow rate of the 1 st ingot group, and a quadrangular-shaped mark 42 shows the relationship between the value Z and the flow rate of the 2 nd ingot group. In fig. 6, the maximum value of the flow velocity of the 1 st ingot group is represented by a maximum value 51, and the maximum value of the flow velocity of the 2 nd ingot group is represented by a maximum value 52. In fig. 6, the value of 70% of the maximum value of the flow velocity of the 1 st ingot group is represented by a value 61, and the value of 70% of the maximum value of the flow velocity of the 2 nd ingot group is represented by a value 62.

As shown in fig. 6, it is understood that the flow velocity near the outlet of the processing tank (position 90) increases as the distance Xd between the tangent lines Ta and Tb perpendicular to the wire electrode 12 increases, regardless of the size of the diameter D of the ingot. Here, when the value Z obtained by normalizing the distance Xd between the tangents Ta and Tb perpendicular to the wire electrode 12 by the diameter D is one fifth or more, it is found that the flow velocity in the vicinity of the exit of the machining tank is 70% or more of the maximum flow velocity. Therefore, the wire electric discharge machining apparatus 1 performs wire electric discharge machining with the distance Xd between the tangent lines Ta, Tb perpendicular to the wire electrode 12 of the 2

ingots

30a, 30b set to 0.2D or more.

Here, it is known that electrostatic attraction force q acts on the line portion R during electric discharge machining of an ingot. Further, the electrostatic attractive force q causes vibration at the line portion R. The vibration of the wire portion R due to the electrostatic attraction q affects the accuracy of the cutting process. Thereby, it becomes important to reduce the vibration of the line portion R. The amplitude δ of the line portion R is approximated as a chord acted on by an external force, and thus it is known that the maximum displacement on the line portion R can be estimated by the following equation (1).

δ＝(qh²)/8T···(1)

In the formula (1), T is the tension of the line portion R, h is the length of the line portion R, and q is the electrostatic attraction force to which the line portion R is subjected. For example, when the ingot is discharge-machined under the conditions that the diameter D of the ingot is 100mm, the tension T is 10N, and the electrostatic attraction q is 0.01N/m, the amplitude δ when the distance Xd between the tangent lines Ta and Tb perpendicular to the wire electrode 12 is changed to 0 to 3D is shown in fig. 7 by the expression (1). Fig. 7 is a diagram showing a calculation result in the case where the amplitude of the wire electrode 12 is calculated using a logical expression for the wire electric discharge machine according to the embodiment. Since the amplitude δ in the wire electric discharge machining of the ingot needs to be suppressed to 20 μm or less, it is necessary to suppress the distance Xd between the tangent lines Ta and Tb perpendicular to the wire electrode 12 to 1D or less, as is apparent from fig. 7.

In the present embodiment, the case where the wire electric discharge machining apparatus 1 is a multi-wire electric discharge machining apparatus has been described, but the wire electric discharge machining apparatus 1 may be a wire electric discharge machining apparatus that machines 1

ingot

30a, 30b 1 by 1 wire electrode 12.

As described above, in the present embodiment, since the cutting process is performed at the interval of 0.2D or more and 1D or less as the distance Xd between the tangent lines Ta and Tb perpendicular to the wire electrodes 12 with respect to the diameter D of the

ingots

30a and 30b, collision of the processing liquid 70 supplied from both sides of the

ingots

30a and 30b can be suppressed. That is, even when the wire electric discharge machining is simultaneously performed on the

ingots

30a and 30b arranged in parallel by 1 wire electrode 12, the machining liquids 70 supplied to the

adjacent ingots

30a and 30b can be prevented from colliding with each other. Further, since the machining liquids 70 can be prevented from colliding with each other, the machining chips can be removed without being accumulated in the machining tank.

The configuration described in the above embodiment is an example of the content of the present invention, and may be combined with other known techniques, and a part of the configuration may be omitted or modified without departing from the scope of the present invention.

Description of the reference numerals

1 wire electric discharge machining apparatus, 11 wire drawing bobbin, 12 wire electrode, 13a to 13d winding guide roller, 14 winding bobbin, 15a, 15b positioning guide roller, 17a, 17b power supply, 19a, 19b nozzle, 20a, 20b machining liquid supply hose, 30a, 30b ingot, 35a, 35b cylinder shaft, 40 machining table, 50 workpiece holder, 60 machining tank, 70 machining liquid, 71a, 71b jet flow, C machining tank, F machining tank depth, P collision point, R wire part, Xd distance.

Claims

1. A wire electric discharge machining apparatus is characterized by comprising:

a holding unit for holding a cylindrical 1 st workpiece and a cylindrical 2 nd workpiece arranged in parallel in the same plane;

a wire electrode that is linearly arranged so as to face the 1 st workpiece and the 2 nd workpiece, respectively, and that performs wire electric discharge machining on the 1 st workpiece and the 2 nd workpiece at positions facing the 1 st workpiece and the 2 nd workpiece; and

a pair of machining liquid supply units arranged at positions along the wire electrode and facing each other with the 1 st workpiece and the 2 nd workpiece interposed therebetween, for ejecting machining liquid along the wire electrode toward the 1 st workpiece and the 2 nd workpiece,

the 1 st workpiece and the 2 nd workpiece have the same diameter,

when the diameter is D, the holding portion holds the 1 st workpiece and the 2 nd workpiece such that a distance between the cylindrical axis of the 1 st workpiece and the cylindrical axis of the 2 nd workpiece is 1.2D or more and 2D or less.

2. The wire electric discharge machine according to claim 1,

a wire cutting unit, which is a portion of the wire electrode on which the wire electric discharge machining is performed, is provided at a plurality of portions with respect to the 1 st workpiece and the 2 nd workpiece, respectively, and the wire electrode performs a multi-wire electric discharge machining.