CN1298505C

CN1298505C - Measuring method for critical electro-discharge machining gap

Info

Publication number: CN1298505C
Application number: CNB2004100252066A
Authority: CN
Inventors: 郭常宁; 马春翔; 雍耀伟
Original assignee: Shanghai Jiao Tong University
Current assignee: Shanghai Jiao Tong University
Priority date: 2004-06-17
Filing date: 2004-06-17
Publication date: 2007-02-07
Anticipated expiration: 2024-06-17
Also published as: CN1593845A

Abstract

A method for measuring the critical discharge machining gap used in the field of special processing technology. Firstly, the electrode is in contact with the workpiece. The contact point is point A, and its coordinate position is zero X=Y=Z=0. The plane of the workpiece is parallel to XOY, so that The electrode retreats 1mm along the Z axis to point B; make the electrode translate the distance ΔX or -ΔX along the positive or negative direction of X to point C; at this time, use the manual manipulation control box to manually descend a minimum distance Δt along the Z axis , the electrode is processed towards the origin X=0, and the electrode is processed in parallel with the gap of Z=1mm-Δt from the surface of the workpiece to reach the point X=0 after passing through ΔX; if discharge occurs at this time, the distance of 1mm-Δt is the critical discharge Otherwise, return the electrode to point C, and then reduce the distance between the electrode and the workpiece surface by 2×Δt, repeat the above-mentioned process to point X=0 until discharge occurs, if the distance between the electrode and the workpiece decreases n times After the first discharge occurs, the critical discharge gap is: 1mm-n×Δt.

Description

The measuring method of critical electro discharge machining gapping place

Technical field

The present invention relates to a kind of measuring method of critical discharging gap, specifically is a kind of measuring method of critical electro discharge machining gapping place.Be used for the special processing technology field.

Background technology

One of key character of discharge processing must make between electrode and the workpiece exactly and maintain a certain distance, to guarantee carrying out smoothly of discharge processing.Critical discharging gap then is meant under certain open voltage effect, the anode-cathode distance that the medium between the positive and negative electrode just can be breakdown.Because the critical discharging gap magnitude relationship arrives the gasification blast of working fluid, the eliminating passage of processing bits, so that relevant with the processing characteristics that discharges, on the other hand, aspect estimation spark machined precision, very important reference role is arranged all.Therefore in discharge working research and electrical process machine design, often can use this critical breakdown value, so simple, convenient, reliably, the measuring technology of critical discharging gap has very important using value cheaply.

At present, in the document of just publishing, yet there are no report relevant for the critical discharging gap method of testing.Only a spot of bibliographical information has been arranged about the method for testing of discharging gap, tested or utilize average machining gap that discharging gap is inferred in these methods or by means of the isolated plant of design voluntarily.Find by retrieval, An Libao has discussed discharging gap and (has claimed in the document: method of testing machining gap) in " the accurate manufacturing technology of aviation " " research of electric spark fine finishining backlash characteristics " literary composition that the 30th volume the 6th phase pp16-18 delivered in 1994, this method is to utilize the manual isolated plant of gap adjustment of design voluntarily, replace the lathe servo feed to change anode-cathode distance, after opening the pulse power, by the hand feed electrode, until normal process state (observing electric wave and pulse counter demonstration discharge frequency) by oscillograph, stop hand feed this moment immediately, close the pulse power, and record amesdial reading this moment, continue manually slow feeding tool-electrode then,, write down amesdial reading this moment until coming in contact with surface of the work, the difference of twice reading of amesdial is the discharging gap value under this processing conditions.After but this method is the necessary manual slack adjuster of design specialized, just can test, and this method of testing has the place that is worth discussion aspect measuring accuracy, as since test the time be close the pulse power after, continue manually slow feeding tool-electrode, until coming in contact, thereby record discharging gap with surface of the work, it is maximum exactly not enough: need the special manual slack adjuster, the testing cost height; Because when using hand feed, the amount of feeding of unit interval can be not big, probably produce the discharge back and cause the continuous impulse discharge at the critical discharging gap place, mistake is used as critical discharging gap as discharging gap, the error on the principle therefore occurs, and test error is bigger.

Summary of the invention

The objective of the invention is at prior art above shortcomings and defective, a kind of measuring method of critical electro discharge machining gapping place is provided, make its low cost, directly formulate testing scheme according to the critical discharging gap principle, reduce measure error, improve precision, method is simple, reliable results, accurately.

The present invention is achieved by the following technical solutions, and the critical discharging gap of indication of the present invention is meant the distance that just can produce discharge between workpiece and the electrode, and around this principle, the measuring method step is as follows:

(1) electrode is contacted with workpiece, contact point is the A point, and workpiece planarization is parallel with plane X OY, and to set this contact A coordinate position of order be zero (X=Y=Z=0), make then electrode along Z axle rollback (rising) 1mm to coordinate B point.The anode-cathode distance of general discharge processing can not surpass 1mm, and therefore setting Z axle rollback 1mm is impossible discharge position.

(2) influence each other in order to reduce between workpiece and the electrode, make electrode along X positive direction or a certain distance, delta X of negative direction translation (or-Δ X) to the C point.

(3) at this moment, the manual control control box that uses lathe to carry, along Z-direction, manually behind possible minimum range Δ t of decline, setting the electrode machine direction is directions X, promptly processes to initial point (X=0), starts the processing key, electrode is with the height (gap) of distance surface of the work Z=1mm-Δ t, through Δ X road through after processing abreast arrive X=0 point place.

(4) observe between workpiece and the electrode whether produced discharge, discharged if produce between workpiece and the electrode, t is exactly a critical discharging gap apart from the 1mm-Δ; If not discharge, make electrode turn back to the C point, and then make electrode and surface of the work distance reduce 2 * Δ t, promptly along Z direction decline 2 * Δ t, repeat above-mentioned to X=0 point place process, discharge occurs between workpiece and electrode, produce discharge for the first time if reduce the back through distance between n sub-electrode and the workpiece, then critical discharging gap is: 1mm-n * Δ t.

More than be parallel with XOY plane when surface of the work, electrode moves in the XOZ face, and machine direction is X (X) axle, the critical discharge test method when direction of measurement is the Z axle.In like manner, when electrode moves in the YOZ face, machine direction is Y (Y) axle, when direction of measurement is the Z axle, repeating step 1) ~ 4) measurement procedure, can carry out critical discharge test equally, record critical discharging gap.

Perhaps workpiece and electrode are after Y-axis is rotated 90 ° along (contrary) hour hands, (Z) axle, direction of measurement are that X is (X) during axle when electrode moves in the XOZ face, machine direction is Z, repeating step 1) ~ 4 measurement procedure), be that surface of the work is parallel with YOZ, (Z) direction of principal axis carries out critical discharge test, can record critical discharging gap equally along Z; (Y) axle, direction of measurement are that X is (X) during axle when electrode moves in the XOY face, machine direction is Y, repeating step (1) ~ (4) measurement procedure, be that surface of the work is parallel with YOZ, carry out critical discharge test, can record critical discharging gap equally along Y direction.

Perhaps workpiece and electrode are after X-axis is rotated 90 ° along (contrary) hour hands, when electrode moves in the YOZ face, machine direction is Z (Z) axle, direction of measurement is Y (Y) when axle, repeating step (1) ~ (4) measurement procedure, be that surface of the work is parallel with XOZ, (Z) direction of principal axis carries out critical discharge test, can record critical discharging gap equally along Z; When electrode moves in the XOY face, machine direction is X (X) axle, direction of measurement is that (promptly surface of the work is parallel with XOZ for Y) when axle, repeating step (1) ~ (4) measurement procedure for Y, (X) direction of principal axis carries out critical discharge test, can record critical discharging gap equally along X.

Direction of rotation in above-mentioned is: the positive direction along reference axis is looked, and consistent with clock and watch hand motion direction is clockwise, is counterclockwise on the contrary.

Beneficial effect of the present invention: 1) cost is low, during test except discharging processing machine, electrode, workpiece steps up outside the device, without any need for other auxiliary equipment and instrument and meter or isolated plant; 2) operation is simple for method, reliable, and be not subjected to the restriction of other condition; 3) if do not consider the discreteness at random of testing, method measuring accuracy height, good reproducibility, no original reason error, measuring accuracy are exactly that this lathe is in the hand feed precision on the direction of feed. and when being 1 μ m when the hand feed precision, this method of testing precision also is 1 μ; 4) solved the problem of testing critical discharging gap in the discharge processing, be research discharging processing machine reason, particularly study the gasification blast of working fluid, the eliminating channel sized of processing bits, the stability of discharge, estimation spark machined precision is so that research discharge processing characteristics all has important effect and reference value.

Description of drawings

Fig. 1 the inventive method schematic diagram

Discharge trace figure during the critical discharge of Fig. 2

The specific embodiment

Content with the inventive method provides following examples in conjunction with the accompanying drawings:

1. preparation: machined electrode on lathe (red copper Φ 10) side and end face, on grinding machine, workpiece (material: Cr13, size 50 * 30) upper and lower surface is polished, the depth of parallelism of upper and lower surfaces is 3 μ m.And with sand paper (1500# 3000#) is ground to light with electrode end surface and surface of the work respectively for 600#, 1000#.Side and end face squareness 3 μ m during beveled electrode,

2. install: workpiece is installed on the workbench of Xia Mier 35 serial spark-erosion machine tools and steps up, in the main shaft chuck of then electrode being packed into.

3. set: make electrode and workpiece contact and set the coordinate X=Y=Z=0 of this A at A point (seeing accompanying drawing 1).Then electrode is risen to Z=1mm, again electrode is moved to X=100mm (this moment, electrode end surface was away from surface of the work) along the X-axis positive direction.The setting machine direction is an X-axis, is worked into X=0 point place from X=100mm.

4. test process: the control box that at first uses electrical discharge machine to carry makes electrode at the Z-direction 1 μ m that descends, and starts the processing key, and the result is discharge not.Repetitive process 3 and 4 makes electrode get back to X=100, and Y=0 behind the position of Z=1, makes the electrode 2 μ m that descend once more, starts the processing button.Up to descending 900 μ m, discharge for the first time and be the single-shot discharge just have when promptly the gap is 0.1mm. used processing conditions 1 and processing conditions 2 respectively for validation test result's correctness, test result is as follows:

	Critical discharging gap
	Critical discharging gap	Processing conditions 1	0.1mm
Processing conditions 2	0.1mm	Processing conditions 1	0.1mm

* processing conditions 1: open voltage=120V; Discharge current=24A; Pulse width=200 μ s; The average time-delay reference value 30 that punctures.

* processing conditions 2: open voltage=120V; Discharge current=32A; Pulse width=200 μ s; The average time-delay reference value 30 that punctures.

Critical discharge the results are shown in accompanying drawing 2 (a) (b):

The discharge trace photo of the critical discharging gap when (a) figure is processing conditions 1, as seen from the figure, the discharge trace also is not completed into complete discharge hole, and has only one, and the discharge trace that just can produce disruptive discharge also should be incomplete discharge discharge trace.

Critical discharge trace photo on the workpiece of discharge back was compared with condition 1 when (b) figure was processing conditions 2, only was that discharge current is big, and the discharge trace remains a not exclusively result of discharge.

Claims

1. A method for measuring a critical EDM gap, characterized in that the steps are as follows:

(1) First make the electrode contact with the workpiece, the contact point is point A, the workpiece plane is parallel to XOY, and set the coordinate position of this contact point A as zero X=Y=Z=0, then make the electrode retreat along the Z axis 1mm to coordinate B point;

(2) In order to reduce the interaction between the workpiece and the electrode, make the electrode translate a certain distance ΔX or -ΔX to point C along the positive or negative direction of X;

(3) At this time, use the manual control box that comes with the machine tool to manually descend a minimum distance Δt along the Z-axis direction, set the electrode processing direction as the X direction, that is, process to the origin X=0, and start the processing key , the electrodes are processed parallel to point X=0 after going through the ΔX path with a gap of Z=1mm-Δt from the surface of the workpiece;

(4) Observe whether there is a discharge between the workpiece and the electrode. If there is a discharge, the distance 1mm-Δt is the critical discharge gap. Otherwise, return the electrode to point C, and then reduce the distance between the electrode and the surface of the workpiece by 2×Δt. That is, drop 2×Δt along the Z direction, repeat the above-mentioned processing process to X=0 point, until the discharge occurs between the workpiece and the electrode, if the first discharge occurs after n times the distance between the electrode and the workpiece decreases, then the critical The discharge gap is: 1mm-n×Δt.

2. The method for measuring the critical EDM gap according to claim 1, characterized in that, when the electrode moves in the YOZ plane, the machining direction is the Y or -Y axis, and the measurement direction is the Z axis, repeat step (1) -(4) Measure the operation process, conduct a critical discharge experiment, and measure the critical discharge gap.

3. The method for measuring the critical EDM gap according to claim 1, characterized in that, after the workpiece and the electrode rotate 90° clockwise or counterclockwise around the Y axis, when the electrode moves in the XOY plane and the machining direction is Y or - When the Y axis and the measuring direction are X or -X axis, repeat the steps (1)-(4) measurement operation process, that is, the surface of the workpiece is parallel to YOZ, and the critical discharge experiment is carried out along the Y or -Y axis direction, and the critical discharge is measured. Gap; Similarly, when the electrode moves in the XOZ plane, the processing direction is Z or -Z axis, and the measurement direction is X or -X axis, repeat steps (1) (4) to measure the operation process, that is, the workpiece surface is parallel to YOZ , carry out the critical discharge experiment along the Z-axis direction, and measure the critical discharge gap.

4. The method for measuring the critical EDM gap according to claim 1, characterized in that, after the workpiece and the electrode rotate 90° clockwise or counterclockwise around the X axis, when the electrode moves in the YOZ plane, the processing direction is Z or - When the Z axis and the measurement direction are Y or -Y axis, repeat steps (1)-(4) measurement operation process, that is, the surface of the workpiece is parallel to XOZ, and the critical discharge experiment is carried out along the Z or -Z axis direction to measure the critical discharge Gap; when the electrode moves in the XOY plane, the processing direction is X or -X axis, and the measurement direction is Y or -Y axis, repeat steps (1)-(4) to measure the operation process, that is, the workpiece surface is parallel to XOZ, along The critical discharge experiment is carried out in the X or -X axis direction, and the critical discharge gap is measured.