JPS58114823A - Machining control system for wire-cut electric discharge machine - Google Patents

Abstract

PURPOSE:To suppress the error produced due to the vibration of the electrode within several micrometers by a method wherein the machining of circular arcs is performed by correcting the data of deflection produced during straight line machining and the data of radius instructed in respect to the radius of wire electrode and the gap length at straight line machining. CONSTITUTION:An operating unit 5 obtains a radial deflection DR and a tangential deflection DT by means of the amount of deflection DO produced during straight line machining, which is stored in a main memory 8 in advance, and instruction data for machining or instructed machining speed F, an instructed radius R and a machining width epsilonO and further obtains a radius difference DELTAR to correct machining path in order to obtain a radius value R' corrected with the amount of deflection. Next, the operating unit 5 obtains a radius value R'' corrected with DELTAR1 or DELTAR2, which is obtained by means of the resultant radius value R', the radius r of the wire electrode stored in the main memory 8 and the gap length at straight line machining. The radius value R'' together with the instruction data for machining is sent through a bus 12 and an interface circuit 9 to a table 10 in order to control the movement of the table 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a machining control system for a wire-cut electric discharge machine that compensates for shape errors that occur during circular arc machining.

A wire-cut electrical discharge machine creates a predetermined gap between the wire electrode and the workpiece, and applies a voltage between the wire electrode and the workpiece to generate a spark discharge at this gear joint. It is something that scrapes away. Therefore, if the workpiece is moved relative to the wire by Kl based on the machining command data, it is possible to process the soak into the desired shape of PjT. By the way, in a wire-cut electrical discharge machine, as shown in FIG. 1, the wire wire &1 cuts the workpiece 2 while moving along its #15 in a predetermined direction.

Theory 2 As shown in figure 2, wire 1 [pole 1 and work! Pressure for discharge is generated in between, and as a result, the wire electrode 1 is pushed back in the direction of the arrow, that is, in the direction opposite to the direction of movement. Therefore, the wire electrode 1 faces # from the position of the wire guide 44. In other words, the wire electrode 1 is bent. When performing straight line electrical discharge machining, this amount of deflection V
There is no problem with the i-field, but as shown in Figure #145, I had a friend who performs arc machining send S7 to workpiece 21 based on the machining command.
If the wire electrode moves in an arc with the radius of the foot, the wire electrode at the discharge portion will be dragged inward due to the bending of the wire electrode due to the above-mentioned electric current. This ninth point, the actual circular part machining locus differs from the commanded circular shape 5m (solid line in the figure), and the machining shape sag as shown by point @5b.

In order to prevent this, the applicant has applied for a technology that corrects the commanded machining radius based on the commanded machining radius and the specified amount of deflection of the wire electrode, and performs circular arc machining as instructed, regardless of the deflection of the wire electrode. did.

Although the error between the actual machined arc shape and the commanded arc shape has been significantly reduced by implementing the locking technology, it is not sufficient when ultra-high precision machining with an error of several microns is required.

Therefore, an object of the present invention is to provide a machining control system for a wire-cut electric discharge machine that can reduce shape errors during arc machining.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

One of the reasons why the actually machined actual arc radius differs from the commanded arc radius during arc machining is that the wire electrode bends due to discharge pressure. Therefore, measure the amount of deflection [21,
When the arc radius was corrected based on the amount of deflection, there was still an error of about 10-odd microns. This degree of error is not a problem under normal usage conditions, but when processing with a high ff1l is required, it is required that the difference in VCFi be further reduced.

As a result of various inspections, the present inventors found that vibration of the wire electrode is one of the causes of errors. That is, during electrical discharge machining, the wire electrode vibrates due to the pressure caused by the generation and disappearance of discharge bubbles, and due to this vibration, the side surface in the machining direction is further machined.

The width of the processed groove is larger than the diameter of the wire electrode.

This vibration shadow 41 is caused by the left and right areas 15, 15 during the machining of the 61 wire side surface during the 4th I fal direct-VΩ machining.
' will be the same and there is no problem. Shi, Kaji, #44 figure fbl
When machining an arc of During the processing of - becomes smaller than .

Therefore, during arc machining, the actual machining arc radius F'i differs from the commanded radius.

Therefore, the machining speed is F, the sword loe width (gap length) when machining tffiill17111 is 6, and the outer arc curve width is σ) @
Let the stopped arc radius be Peng, and the corrected radius during inner circular arc machining be Chi. Similarly, the radius is used when the accuracy force S is required for the outer arc, and the radius is used when the inner arc requires precision.

The following formula is established for each circular arc, where the amount of curling per unit movement during one-line machining (Fxg) and the amount of curling per unit movement during arc machining are 1 river.

F''''''s(f(4'+ r +-') θ
(11F1-, *(he-, -hi)δ
(2) However, # is the angle for unit movement, and r is the radius of the wire electrode.

Since Mi-F/Lump-F/Bird (3) holds here, the equations (11, (21) become.

Similarly, for the radial direction, Bird+γ+'t=1(1r+g, ゛Ji-21 H70ε-#I

(61 horses-r-6=5<1-6, ゛, kl, ;-Re-+-gff71 holds true. ril and R are command arc shapes.

Transforming equation (4), we get g (R 0 g - g, ) = 1. (R+ g, +
r ()a", -1, (R+r+2g) し? (R+
g)=.

10, °, g, = R + r + 2g - ((R + r + 2g) - 2g
(R+g)) (e). To lff1 (5)
Form the formula ff, and expand it by substituting 12 (71), ↑ Su=-R+r+2g+((Rr-r-2g)"+2g(
R-g)) Q(1 and Σ.

Therefore, the radius stop amount to be corrected when machining the outer arc and the correction amount Δ^ of the radius to be corrected when machining the inner arc are as follows.

↓ = C (u+r+2g) -2g (R+g))
-4t-r-g QDΔ8=to-R=riichi■ = ((ft-r-2g) +2# (R-t))
-R+r+g Q3.

For example, R=o2mmb γ=0.11m%g=0.0
For 361LI+, Δto=15μm, Δto=56
It becomes μm.

In this way, if the error caused by the difference in the machining gap in arc machining due to the vibration of the wire electrode is corrected for the radius by the machining gaps g, , g, highly accurate machining can be obtained that is less than the target value.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Figure #5 is a configuration diagram of an actual journey example according to the present invention, and in the figure, 5
Processing of NO tape 11 using a calculation unit such as 1i Microgrossenosa, 6 is Nazo reader! -Command data (start point data, point data)'4 is read. 7
The &j operation panel is used to command plate thickness and feed speed. 8 is the main memory, and 7)
11, command data and performance programs are stored. 9ζ
'Uinter 17 is connected to the 1-pull 10 on which the work is placed.

12 is Totl et al.

. First, machining command data is read from the 1-reader 6K, and the data commanded from the operation panel 7 and the memory 8 are stored in the book.
ni^self(hasa't.・zoL-(, operation unino L5t
J. The control of memory 8 is used for the program, and the data in memory 8 is used to write table 10 through the intern ace circuit 9.
I-transfer M control.

When the calculation unit 5) receives the command, the processing (flG data) corresponding to this processing command is read from the memory 8. 10 cuff data) is also calculated.

First, the calculation unit 5 calculates a nine-radius value corrected by the amount of deflection, and then converts this radius value I into Q.

A further corrected radius value formula is obtained by substituting the radius r1 of the wire electric chestnut into the formula or formula 0 together with the gap length during straight line machining. Here, in order to simplify the explanation, correction based on the amount of deflection will be explained first.

Figure M6 is an explanatory diagram of radius correction by deflection filter.

In the figure, go is half the width of the groove 5 machined by the wire 1, which is larger than the radius of the wire.
Assume that the wire has moved by t.

Considering the machining jld* at the position of angle α as a workpiece of unit radius, dv = (a-s.asa) * satxgo-d
α・Dynamic α/dt 03). Here, It is the command radius value, and the feed rate is F, then F=1 as well. ・ θ ・ ・ ・
Becomes I.

Therefore, equation (1) becomes as follows.

Assuming that the discharge occurs only at the front of the wire, let dV be α
= 7 to integrate from 0 to xi, and V = 2Fg.
αe Now consider the pressure applied to the wire at the angle α. The following assumptions are made as a premise.

■The pressure that increases by 71L on the wire surface due to discharge is the discharge frequency IN.
The discharge fineness is proportional to the amount of machining per unit time.

■The pressure moves perpendicular to the wire 1jll.

Therefore, the pressure applied to the wire is P, the pressure in the radial direction is PR1, and the pressure in the contact direction is Pt.

The radial pressure PR is obtained as follows.

dPB= dP-cxxxa (I
T) = dV (2) α 01 (However, K is a proportionality constant, which originally changes if the discharge energy differs, but here it is assumed that the discharge energy is equal.) This is expressed as α = 0 ~ The tangential pressure applied to the wire P・rV
i・dPT=dP・1α? υα
Integrate from =0 to π, P = - K - F - g, (2) Here, ■ and PT do not depend on the arc radius R. That is, each m
- equal to the amount processed and the tangential pressure applied to the wire during machining.

Next, the deflection fi of the wire is approximately determined using FIG.

From Figure 7, it is expressed as. That is, since it is proportional to the force P applied to the wire, if the deflection during linear machining at the machining speed (-) is set to 8, and the deflections due to the 2-piece and PR are set to 8 and 9 to 8, respectively, the following equation is obtained.

For this reason, the radius difference Δ)t between the normal trajectory and the corrected path during circular arc machining is Δa=, Aγ 10-1 @ Therefore, the deflection during straight line machining and 710 machining is calculated in advance. If the column setting is stored in the memory 8, the DO work command speed [F& will be given to calculate the height, the height will be calculated, the JR will be calculated using the Kan formula, and the deflection type correction of the arc radius can be performed.

That is, the arithmetic unit 5#''i stores the data in the main memory 8.
・[・To the amount of deflection during machining, the machining command data, continuous speed longitudinal F, command half 44) t%no machining width C0, the deflection from the formula ψ), or. [2. Calculate JR and obtain the radius value R' (=R + ΔR) corrected by the deflection. 6th calculation unit) 5Fi The calculated radius value R is 00 Substituting the formula and the formula 03, execute the 0υ formula or the Fiaa formula, and obtain Δ or Δ
The corrected radius value d (m + Δ8 or + Δ−)
seek.

The arc radius data corrected in this way is sent to the calculation unit 5.
Calculation 12, along with the above-mentioned machining command data, pass 12,
The data is sent to the table 10 via the interface circuit 9t, and the movement of the table 10 is controlled.

As described above, the present invention corrects the deflection of the commanded radius value based on the deflection data, and also corrects the radius value based on the radius of the wire electrode and the gap length during linear machining, thereby solving the problem caused by the vibration of the wire electrode. Errors during circular arc machining are extremely small, on the order of several microns, which can be ignored. Therefore, it is possible to perform machining with higher precision, and greatly expand the usable range of the wire-cut electric discharge machine, which has the advantageous effects of UF discharge and the like.

However, according to the gist of the present invention, various f-types are available, and these are not included within the scope of the present invention. There isn't.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the wire flexure, Figure 1 is a diagram explaining wire deflection, Figure 4 is a diagram explaining white pig iron processing, and Figure 4 is the principle of the present invention. Diagram to clarify. Fig. 5 shows a schematic diagram of an embodiment of the present invention, and Fig. 6 and Fig. 7 show explanatory diagrams of a flexible sleeve used in the present invention. 1 Wire electrode, 2... Work, 5... Groove, 4... Wire guide, 5... Arithmetic unit, 6... Tape reader, 7... Operation panel, 8... Memory, 9... Interface circuit, 10... table, 11... NO
Tape% 12...Bath, 13.15'-lit line processing area, 14...Outer machining area, 15...Inner processing f
s castle. Figure 5 l 1,

Claims (1)

[Claims] Wire cutting involves applying a voltage between the wire electrode and the workpiece, scraping the workpiece with discharge energy, and moving the sales wire electrode and the workpiece relative to each other in response to machining command data from a control unit to process the workpiece into a predetermined shape. In an electric discharge machine, the control aS corrects the radius data commanded by the nine deflection data measured in advance during nine fi tightening machining, and also corrects the radius data by the radius of the wire electrode and the gap length during straight machining. A machining control method for a wire-cut electric discharge machine, which performs electric discharge machining while performing relative movement according to the corrected arc radius.