JPS5828421A - Electron discharge method by wire and its device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a wire electrical discharge machining method and apparatus.

A conventional wire electric discharge machining (hereinafter abbreviated as EDM) apparatus includes a head assembly attached to a machining tool body and a numerically controlled positioning table. The wire device also includes a spool assembly on which a thin wire is stretched tightly between two spools.

A drive spool moves the wire from one spool to the other at a constant speed.

At this time, the effective processing length of the wire is ensured between the two spools. This length is approximately 10.161 to 20',
It is 32 cm. The cutting speed depends on the dimensions of the wire, the current flowing through this wire, and the feed rate set to the depth of the cup. Fully ionized water is not only commonly used as a dielectric but also serves to wash away corrosive particles generated during cutting operations. All electrical discharge machining (
As is known in EDM (EDM) operations, wire electrodes produce uniform over-cutting or over-burning. This over-cutting or burning is approximately 0.0 mm larger than the diameter of the electrode.
From 00508 cm to 0.00762 cIIL becomes a large number.

In the extrusion of ceramic honeycomb structures used in catalytic exchangers of internal combustion engines, it is necessary to form extrusion dies with fairly long and narrow grooves. The fairly long (narrow) groove is not only straight and extends across the front face of the die, but also has parallel side walls and a uniform surface finish with no blemishes. Furthermore, such a length (a narrow groove is approximately 8.89 mm)
(length over J, approximately Q, 1524 (depth over m, 0
．． Thicker than 03048cIr+ (has no width).

U.S. Patent No. 25264234. Known wire electrical discharge machining (BDM) methods, such as those disclosed in US Pat. No. 4,205,213 and US Pat. No. 4,233,486, are all capable of forming grooves. However, such methods limit the effective depth of a groove that can be cut in the surface of a workpiece with a wire of a given diameter to a length of more than 8.89 mm or more. That is, for example, in the known wire electrical discharge machining (BDM) method, the depth is reduced to 0.1 during the cutting process.
The difficulty of flushing away corrosive particles from within small grooves of 524 m or more limits the effective depth of cut. When the wire cutting process is stopped due to the deposition of corrosive particles, the groove width at that depth is significantly enlarged or improperly overcut, resulting in uneven grooves and wire breakage. arise.

Almost all wire electrical discharge machining (EDM) methods are
an arrangement for flushing longitudinally or coaxially with the wire to provide fully ionized water longitudinally along or coaxially with said wire to create a longitudinal notch or groove in the workpiece; is used. However, when machining the longitudinal grooves using the wire method, the coaxially fed flushing medium is deflected at the edge of the workpiece and therefore
This dielectric deflection makes cutting operations inefficient or impossible. Inefficient machining conditions are when the machine repeatedly returns from the cutting surface and the electrical discharge is interrupted, or when orange sparks are observed in the cutting area, or when persistent wire breakage occurs. appears in As mentioned above, such inefficient machining conditions not only have a severe impact on the ability to machine a groove to a given desired depth (but also to the ability to form the same groove from start to finish). In addition, when cutting with conventional wire electrical discharge machining (EDM) methods, enlarged or flared conditions often occur at the entrance of the groove close to the machined surface. It has been discovered that.

The present invention overcomes the problems present in known wire electrical discharge machining (EDM) methods and equipment and provides parallel sidewalls with a uniform surface finish of 0.1524 steel or higher and preferably 1. 8. Depth of 524α or more;
This makes it possible to repeatedly form a plurality of long, thin grooves having a length of 89 crIL or more.

One embodiment of the present invention relates to the use of a longitudinal path in which the electrical discharge machining wire moves along the length of the cutting surface of the workpiece.

Also, although this passageway is open at each end, it is substantially closed along its length, allowing the dielectric fluid to flow longitudinally around the EDM wire beyond the direction of extension of the cut surface of the workpiece. Direction is made so that the flow follows a directional path. The enclosed longitudinal passage may be formed by a scouring device or trough having a longitudinal channel formed therein for cutting the workpiece. located opposite the surface.

Other embodiments of the present invention include oversized pre-cuts or pilot holes formed in the surface of the workpiece to facilitate forming long narrow grooves in the workpiece by wire electrical discharge machining methods. Regarding the use of shaped grooves. By utilizing an enlarged precut or guiding pilot groove in the surface of the workpiece, it is possible not only to virtually double the depth of cut obtained with wire electrical discharge machining methods, but also to increase the cutting depth. The effect of increasing work efficiency can be obtained. The pilot hole-like groove allows for efficient coaxial removal of corrosive particles from within the groove being cut.

1.2 and 3, a flushing device or trough assembly 10 for a wire electrical discharge machining method is shown positioned proximate a cutting surface 72 of a workpiece 70. . The trough assembly 10 includes:
A mounting for attaching the trough assembly 10 to a wire electrical discharge machine support structure (not shown) includes a bracket 12.

The guide stand 14 is attached to the bracket 1 with cap screws 16.
2, the cap screw 16 projects through a groove 18 formed in the mounting bracket 12. The guide stand 14 has a pair of upper and lower holes 20 located on the outside, and a flanged bearing member 22 for slidably receiving a guide pin 24 is mounted in the holes 20. The guide pin 24 has one plunger 26 in the recess 28.
Fixed. This single granger 26 is bolted to a trough member or a receiving base 30 with a screw or bolt 32 or the like.

A recess or groove 36 is provided in the front surface 34 of the trough member 30 along its longitudinal extension direction, and the groove 36 is open on the front surface 34 side and extends from the top and bottom ends of the trough member 30 in the vertical direction. It is open at the sides, with the top and bottom openings proximate each end of the cutting surface 72.

If desired, a plurality of openings 4 may be provided in the trough member 3o.
By forming a passageway with 0 and communicating it with the channel 36, flushing means may be formed transversely to the cutting area by the wire 13-. Furthermore, a plurality of discharge ports or water discharge passages 42 are provided in the trough member or receiving table 3o,
These outlets 42 may communicate the groove 36 with the outer surface of the receiving base 3o to facilitate the discharge or discharge of excess flushing fluid from the groove 36.

A wire W used in a standard wire electrical discharge machining device is connected to the cutting surface 7 of the work piece 70 as indicated by the solid line in FIG.
2 and in its cutting position to form the groove S shown in FIG. 2 by the dashed line W'. It will be appreciated that the longitudinal passageway is formed by the channel 36 and the groove S around the wire W. and the longitudinal passage directs the axial flow of the dielectric flushing fluid along the longitudinal length of the wire W;
At this time, the corrosive particles are removed or washed away from the small grooves S formed by the wire W.

The front surface 34 of the trough member 30 is held opposite the cutting surface 72 of the workpiece 70 to contain the dielectric fluid in a longitudinal or axial passage around the wire W during the cutting process. Make it. A guide pin 44 is fixed to the single plunger 26 and projects into a hole 46 formed in the guide base 14 . Additionally, a spring 48 seated at the end of the pilot hole 50 in the guide stand 14 is positioned around the guide pin 44 and urges the trough member or receiver stand 30 outwardly to engage the cutting surface 72 of the workpiece 70. It abuts against the back surface of one granger 26 for engagement in the operating state. A restraining washer assembly 52 is secured to the rear end of the guide pin 44 to limit forward movement of the single plunger 26 relative to the guide platform 14. A finger-operated handle 54 extends outwardly from the single plunger 26 for manually sliding the trough member 30 toward and away from the workpiece 70. Although the channel 36 is shown as having an arcuate shape in FIG. 2, the channel 36 of the trough member 30 has an engineered shape 56 as shown in FIG. 4 and a T-shape as shown in FIG. The shape 58 may have a rectangular shape 60 as shown in FIG.

A long wire with parallel side walls with a uniform surface finish (slots 36 and S) is formed around the wire when cleaning unwanted particles from the cutting area to facilitate the formation of narrow grooves.
The longitudinal passages formed by. As a particular embodiment, the rectangular channels 60 formed in the trough member 30 have a channel depth of about 0.127c+n and a channel depth of about 1.
It can have a width of 27 cm.

The length of the groove, regardless of its shape, is substantially equal to the length of the cutting surface being cut. In the case of a CF field without using the trough member of the present invention, troubles in the process are expected when processing with molybdenum wire, and approximately 0.
．． 0254 A wide penetration occurs between our penetration and 0.152cm penetration, and the maximum penetration is rarely 0.152cm.
IIL may be exceeded. When using a molybdenum wire with a diameter of 0.01 cm using the T-shaped groove shown in Figure 5, a slight penetration of 0.03 cIrL was observed, and the same wire was used to form the engineering size shown in Figure 4. When using a groove shape of , a slight penetration depth of about 0.3° is observed.

When the trough member of the present invention is applied, the diameter is 0.0178
cIrL and multiple 0.002 cm brass wires, and the curved channel of FIG. 2, or approximately 0.127 cm.
By using the rectangular grooves of Figure 6 with a depth of cWL and a width of approximately 1.27 crrL, high quality grooves were formed on the face of each die with cutting surfaces of 17.145 cm and 20.32 cm. can do. The standard deviation of the groove dimensions is approximately 0, depending on the material used and the quality of the workpiece.
．． Enters between 005crIL and 0.01524 cItL. These results indicate that, compared to not using the present invention,
This indicates that when using the trough member of the present invention, the work piece can be machined to a much greater depth and finished to a uniform, parallel surface.If desired, axial In connection with flushing, the opening 040 should be
It is also possible to flush in the opposite direction1, which is particularly effective when applying thin molybdenum wires. Although it has not been proven necessary for all wire applications, it has been found that the use of this technique significantly increases transparency.

Referring to FIGS. 7-9, a cross-sectional portion of the workpiece 10 is enlarged and shown as having a pre-cut or guiding groove 112. A preliminary cut 112 is formed in the machining surface 114 by the electrical discharge machining wire 21 and extends to a depth d. The long narrow groove 116 has parallel sides with a uniform surface finish, and extends from the inner end 113 of the pilot hole-shaped groove 112 to a depth D of the workpiece 1.
It extends within 10. A wire 20 of a wire electrical discharge machine is shown near the inner end 118 of the groove 116. As shown in FIG. Width W is wire 1
20 in diameter and length (which is substantially thicker than the width W of the long narrow groove 116 (and said width W is 20 mm thicker than the width W of the long narrow groove 116).
~3 times the number. Desired groove 1 in workpiece 110
16 is formed, the upper surface 114 of the work piece 110
By cutting down to the bottom 113 of the prepared groove 112, the prepared groove 112 can be eliminated. That is, depth d is removed.

As shown in FIG. 8, when a workpiece 110 is to be made into an extrusion die 130, a new surface 1
24 is an extrusion die type working/discharging surface or exit surface 12
4, and a plurality of long thin grooves 116 are formed in the die mold 1.
30 of the discharge surfaces 124 are formed.

As noted, groove 116 has a depth D shown in FIG.
side edges 1 of the die 130 until a distance equal to 1 is reached.
Extends 19- into 26.

Although only the broken portion 124 on the surface of the die 130 is shown in FIG. 9, it is clear that the groove 116 extends in a criss-cross pattern over the entire surface 124 of the die 130, and at its widest point. , extending beyond the maximum diameter of the die, which is approximately 21"312α or greater.

The above basic wire electrical discharge machining method is approximately 0.0254
It is possible to machine grooves with a width greater than cWL,
The present invention also provides Q, a width of 0178α or less, and a width of 6.254
To make it possible to accurately and reproducibly process long, thin, and tall precise grooves having a depth of cm or more. An enlarged precut or guiding pilot groove is initially formed in the surface of the workpiece with a width of about 1.5 to 35 times the width of the desired groove to be formed in the workpiece.

The depth of the pilot groove can vary from about Q, 127 cm to about 0.1381 crIL, with an average effective depth of about 0.2159 cm. In view of the time and cost factors involved in forming an enlarged pilot groove and the fact that #≠ does not increase, the reason for forming a pilot groove that grows a maximum depth of about 0.38 cm or more is reasonable. It is thought that there is no such thing.

When the search for the pilot hole-like groove is about 0.0762 cm or less, the standard deviation of the required groove increases considerably.

This results in undesirable non-uniformities in the parallelism and straightness of the desired grooves cut. For example, when the pilot hole has a depth of about 0.381 cm, the workpiece has a depth of about 0.381 cm.
Effective penetration was achieved to an average depth of 32,766 cIrL, with a standard deviation of 0.004547E, but in a similar test, when the pilot hole depth was 0.0762 cIIL, the standard deviation was 0.0132 cfL, approximately 0. .03
It was found that an average depth of 15 crIL was obtained. Furthermore, when using a pilot hole of only 0.0762α, the average cutting speed during the final penetration of 0.045721 is low.
To be flat.

I understand.

As noted above, uncontrolled and irregular overcutting that occurs when cutting is stopped due to inefficient flushing or removal of particles from the groove is undesirable; It will be appreciated that a uniform overcut is obtained during normal machining. That is, in a preferred embodiment, in order to form the guide or pilot hole-like groove 112 on the front surface 114, 0.0254 crrL is used.
A diameter of brass wire is used to form an average width W of about 0.03048°. The guide groove 112 is approximately 0.21
machined to a depth d of 59cWL, then 0.0127c
A long (and narrow) working groove 116 can be formed using a molybdenum wire having a diameter of WL.

At this time, straight grooves 116 with an average depth of about 0.014986 crn and a standard deviation of about 0.0004572 cIIL are formed with good reproducibility.

The maximum length of the groove formed in the workpiece is equal to the maximum diameter of the extrusion die 130 made from this workpiece,
17.145cWL to 20.3 according to required die type
The length will be 2crrL. Various materials that can be processed by the above method include EZ-Cut20, cold rolled steel, D-2 steel, crucible CPM-10V, IFerr.
-=6-1ic.

Available in stainless steel and high nickel alloys. However, the above method is in fact applicable to tool steels, carbide materials, hot ISO steels, vacuum melted steels, and to improve the accuracy of forming the pilot grooves of the present invention. Although the machine was not explained in detail,
Said pilot groove or enlarged preliminary cut 112 acts as a tubular wash-out chamber for the dielectric fluid supplied to the cutting area during the EDM operation and as such removes corrosion particles in the groove 116 generated during cutting. Sympathize with the fluid 11
It is believed that it will be easy to remove from 6. The corrosive particles, if not removed as described above, will limit the effective depth and cutting speed. Said coaxial flushing is ensured by pilot-hole-like grooves, thus increasing the efficient removal of corrosion particles. When completing the formation of the long and narrow groove 116 to form the discharge groove of the die 130, the surface 114 is removed by lowering the enlarged pilot hole-like groove 112 to the die working surface 124 and removing it. .

Although the presently preferred embodiments of the invention have been disclosed, it will be appreciated by those skilled in the art that the wire cutting method of the invention can be used to form virtually any article and is within the scope of the claims. It will be understood that various substitutions and changes may be made without departing from the spirit and scope of the invention as described.

[Brief explanation of the drawing]

1 is a side elevational view of a washing device or trough of the present invention positioned facing the cutting surface of a workpiece; FIG. 2 is a top plan view of the device of FIG. 1; 3 is a front elevational view of the apparatus of FIG. 1 with the work piece omitted and rotated 90'; FIGS. 4, 5 and 6 are views of the apparatus used for the trough member of FIG. 1. FIG. 7 is a large enlarged partial cross-sectional view of a workpiece showing grooves formed in accordance with another embodiment of the present invention; FIG. 8 is a schematic top plan view of various channel configurations; FIG. FIG. 9 is a perspective view in which a part of the die is cut away to show a pattern of discharge grooves formed on the front surface of the die. FIG. 9 is a perspective view of a main part showing a broken portion of the die mold shown in FIG. 8, greatly enlarged to show the formed grooves; 10゛...Washing device (trough assembly) 12...
Mount with bracket 14... Guide stand 1
6... Bag screw 18... Groove 20...
・Hole 22...Flanged bearing member 2
4... Guide bottle 26... One plunger 28... Concave portion 30... Trough member 2
5- 32...l bolt 34...front
Surface 36...Groove (waterway) 4σ...Open
Port 42... Water discharge passage 44... Guide bin 46...
・Hole 48...Spring 50...
Bottom hole 52...Block washer assembly 54...Handle 56...Bottom hole shape 5
8...T-shaped shape 6o...square shape 70...
・Work piece 72...Cutting surface 112...Prepared hole-shaped groove (preliminary cutting) 114...Surface 116...
Groove 118 Inner side end part 120...W
No 121...Ya
Ya 124...Emission surface 126...Side edge Edge 130...Dice type S...
Groove w, w'...Wire-26~FIG, 3 FIG, 4 FIG, 5 FIG, 6FIG,
7 FIG. 9

Claims (1)

[Scope of Claims] (1) A step of preparing a work piece having a cut surface, a step of positioning an electric discharge machining wire close to a required length of the cut surface, and a step of positioning an electric discharge machining wire close to a desired length of the cut surface; providing a substantially enclosed longitudinal passageway around the cutting wire along the direction of extension of the cutting surface, the passageway being open at each proximal end; and supplying a fluid to the passageway. directing the fluid around the cutting wire and along the substantially enclosed longitudinal path; and washing away corrosion particles formed during cutting a groove in the surface of the workpiece. A method of forming a groove in a work piece using an electric discharge machining method in which cutting is performed with a wire, comprising: 2. The method of claim 1, further comprising the step of: (2) supplying a dielectric fluid in the axial direction of the longitudinal passageway. 2. The method of claim 1, further comprising the step of: (3) supplying a dielectric fluid to the longitudinal passageway from a direction transverse to the passageway. (4) providing means for discharging the fluid supplied to the longitudinal passage from a direction across the passage between a plurality of open ends of the passage; Method. (5) A trough member having a groove formed on the front surface is positioned so as to be operatively engaged with the cutting surface of the work piece, and the electrical discharge machining wire is arranged in the groove formed in the trough member. such that the channel and trough member form a substantially enclosed longitudinal passageway around the cutting wire along the direction of extension of the cutting surface of the workpiece. Claim 1 including the step of
The method described in section. (6) By electric discharge machining using a wire, a pilot hole-like groove having a width of 1.5 times the width of the required groove to be formed on the workpiece is first cut into the surface of the workpiece. machining the pilot groove to a depth of about 0.030 inches or more; and using a dielectric fluid to wire a desired groove in the workpiece starting from the bottom of the pilot groove. In order to improve the machining process by electric discharge, the cutting speed obtained, and the depth of the required groove, the pilot hole is designed to facilitate washing away the fluid of corrosive particles generated in the groove during electric discharge machining. A method of forming a groove in a workpiece using an electric discharge machining method in which cutting is performed with a wire, the method comprising a step of using a shaped groove. a step of cutting the pilot hole-like groove in the workpiece, a step of electrical discharge machining a required groove in the work piece with a second wire, and a step of cutting the pre-hole-shaped groove in the workpiece with a second wire, and a step of cutting the pre-hole-like groove in the work piece using a second wire; (8) selecting the first wire; (8) forming the pilot hole-like groove having a width approximately 1.5 to 3.5 times the width of the required groove to be processed and formed in the workpiece; The method according to claim 6, which includes the step of processing and forming on the surface of the work piece.
7. The method according to claim 6, further comprising the step of electrical discharge machining the required groove having a depth of In or more with a wire. (10) The method according to claim 6, further comprising the step of electrical discharge machining the required groove having a width of 0.1778 cm or less in the work piece using a wire. (11) The surface of the workpiece is removed and lowered to the bottom of the pilot groove so as to form a new surface at the beginning of the desired groove. the method of. (12) a trough member having a front surface and extending longitudinally; and a trough member formed longitudinally within the trough member along the front surface;
and a channel (water channel) that is open on the front side of the trough member and open at each longitudinal end of the trough member.
and operatively engages the front surface of the trough member against the cutting surface of the workpiece, such that a channel formed between the trough member and the cutting surface allows passage of a wire of the electrical discharge machining equipment. means for forming a substantially enclosed longitudinal passageway along the extent of the cut surface; and means for flushing away corrosive particles formed during cutting a groove in the surface of the workpiece. and means for forming said longitudinal passage for directing and determining the flow of a supplied dielectric fluid along the axial direction of said cutting wire for removal. A device that uses electrical discharge machining equipment to cut with a wire to form a (13) The device according to claim 12, wherein the trough member includes means for supplying fluid to the groove from one direction that crosses the groove. (14) The apparatus of claim 12, wherein the trough member includes means for discharging excess fluid from the channel to the outside of the trough member. (15) The device according to claim 12, wherein the channel formed in the trough member has a rectangular cross-sectional shape. 16. The apparatus of claim 12, wherein the channel formed in the trough member has an arcuate cross-sectional shape. 6-