CN114571019B - Electric spark milling method - Google Patents
Electric spark milling method Download PDFInfo
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- CN114571019B CN114571019B CN202210259872.4A CN202210259872A CN114571019B CN 114571019 B CN114571019 B CN 114571019B CN 202210259872 A CN202210259872 A CN 202210259872A CN 114571019 B CN114571019 B CN 114571019B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
- B23H5/00—Combined machining
- B23H5/04—Electrical discharge machining combined with mechanical working
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
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Abstract
The application provides an electric spark milling method, which relates to the technical field of electric spark milling, and comprises the following steps: a trial cutting step, an online measurement step, a corrected trial cutting step and a corrected online measurement step; firstly, executing a trial cutting step, starting the electrode wire and the guide from a cutter starting point, and performing electric spark milling on the part along the feeding direction to process trial cutting grooves; then an on-line measuring step is carried out, and the machining depth compensation value delta Z and the electrode loss compensation relative speed S are measured and calculated 1 The method comprises the steps of carrying out a first treatment on the surface of the Then, a correction trial cutting step is carried out, a correction starting point is calculated according to delta Z, and the electrode wire and the guide device complete a new trial cutting along the correction feeding direction; then, the corrected online measurement step is carried out to measure and calculate the new rounds of delta Z and S i (i=2, 3, …). The application can automatically keep the electric spark milling depth as the set value, and is beneficial to ensuring the consistency of the machining process and the precision of the depth dimension of the part.
Description
Technical Field
The application relates to the technical field of electric spark milling, in particular to an electric spark milling method capable of automatically keeping machining depth at a set value, and particularly relates to an electric spark milling method.
Background
The electric spark milling technology adopts a layered milling principle, utilizes a numerical control system to control the motion track of a simple-shape electrode, servo controls the discharge gap between the electrode and a part, simultaneously rotates the electrode at a high speed, and the electrode end faces the part to carry out electric spark processing to etch away the material on the surface of the part. Unlike conventional milling techniques, the material removal depth of electric spark milling is directly related to the time that the electrode is swept across a certain location of the part surface, so that control of the machining depth is largely empirical. The layered milling method can control the machining depth of each milling layer, but the layered milling principle also only provides that the layered thickness is smaller than the discharge gap, and the setting of the machining depth of the first layer is also dependent on the experience of the processor. Once the "man, machine, stock, method, ring" is changed, the machining depth of the first layer may be inaccurate, causing milling depth errors. This error can lead to inaccurate depth dimensions of the part and, in severe cases, to an inability to sustain the machining process.
The electrode itself is worn out while the discharge etches away the part material, and the machining depth becomes shallow. In particular, in the field of micro electric spark milling, the effective discharge gap of an electrode to certain high-melting-point metals is narrow, and the loss of the end face of the electrode during the machining is large, so that the end face of the electrode is lost beyond the effective discharge gap within a few seconds, and continuous machining cannot be performed.
The application patent with the publication number of CN106180923A discloses a micro three-dimensional structure electric spark milling method, wherein the forward and reverse milling and forward and reverse alternating milling mode is a mode of carrying out forward milling and reverse milling in the next circle, and compensating the loss of the previous circle by using the reverse electric spark milling in the next circle; the compensation mode based on the contact sensing method is that a tool setting point is set before machining, contact sensing is carried out, coordinates are recorded, machining is stopped after one cycle is finished, the contact sensing is carried out again after the machining returns to the tool setting point, the coordinates are compensated, and then the machining returns to a machining position for machining, and the method is specifically characterized in that once the program is executed for each time, the contact sensing is carried out; the method is characterized in that: the discharge gap was 0.01mm. The application presets the discharge gap as a fixed value, which indicates that the application still has room for improvement in the aspects of processing depth control and electrode loss compensation. The application adopts a contact sensing method to measure electrode loss and performs coordinate compensation during interrupt processing, which proves that each milling track cannot be guaranteed to have equal depth, and still has room for improvement.
If the electrode loss is converted to an electrode compensation rate after contact sensing, it is possible to compensate for the wire electrode loss in real time during milling. However, since there is a certain difference between the discharge condition of the electrode and the trial cut discharge condition during the real-time compensation, the compensation accuracy is to be improved.
The application patent with publication number of CN106077853A discloses a micro three-dimensional part electric spark milling method, wherein a tool electrode enters the bottom of a layer to be processed from a starting point; milling a groove with the length of 0.1-20 mm, ensuring that normal electric discharge machining removal occurs on the corresponding length, and measuring and calculating the length loss rate of the tool electrode; milling a groove with the length of 0.1-10 mm on the spare part under the condition of the selected layering thickness by taking the determined length loss rate as a parameter, completing the pre-deformation of the milled tool electrode, and taking the pre-deformed tool electrode as the layering milling tool electrode of the workpiece; length loss rate of tool electrode = loss length/track length. According to the application, the electrode cuts into the layer to be processed in a side discharge state, so that the problem that the electrode cannot be continuously processed after being worn due to the fact that the effective interval of electrode end surface discharge of some electric processing systems is extremely small under the condition of micro electric spark discharge is solved, the diameter loss of the electrode cannot be supplemented, and the width of a processing track is difficult to be kept consistent; the patent calculates the continuous compensation rate of the electrode by measuring the electrode loss length once, but the application has room for improvement in the aspects of electrode discharge state setting and electrode compensation accuracy because of the difference between discharge conditions of trial cutting processing and compensation processing, especially under the condition of large layering thickness.
Disclosure of Invention
Aiming at the defects in the prior art, the application provides an electric spark milling method.
According to the electric spark milling method provided by the application, the scheme is as follows:
a method of spark milling, the method comprising: a trial cutting step, an online measurement step, a corrected trial cutting step and a corrected online measurement step;
wherein, the trial cutting process step: comprises electrode wires, a guider, a tool starting point, a tool feeding direction, parts and a test cutting groove; the electrode wire and the guide device are started from a tool starting point, electric spark milling is carried out on the part along the feeding direction, test slots are processed, and then an online measurement step is carried out;
the online measurement process comprises the following steps: measuring and calculating a machining depth compensation value delta Z and an electrode loss compensation relative rate S 1 ；
And (3) correcting trial cutting: comprises a corrected starting point and a corrected feed direction; calculating a correction starting point according to the delta Z, and finishing a new trial cutting along the correction feeding direction by the electrode wire and the guide;
the corrected online measurement process steps are as follows: measuring and calculating a new round of deltaz and S i (i=2, 3, …); if DeltaZ and S i If the frequency of the power source is not converged in the preset range, returning to the step of executing the correction trial cutting; if the electric spark milling is converged, the subsequent electric spark milling is performed.
Preferably, the electrical standard, the milling feed rate or the trajectory superposition rate is changed during the milling process, and the subsequent process steps are performed again from the trial cutting process.
Preferably, in the trial cutting step, the electrode wire and the guide machine are used for machining trial cuts on the part;
the electrode wire and the guide device rotate at a high speed in the rotating direction, electric spark milling is carried out on the part along the feeding direction from the starting point until the retracting point, and the test slot is machined.
Preferably, the feed direction is synthesized by a horizontal feed motion and an electrode loss compensation motion, wherein the horizontal feed distance is L, and the electrode loss compensation relative rate is S 0 The compensation distance is S 0 L, direction is-Z.
Preferably, if there is empirical data on the electrode loss compensation relative rate, then S will be directly 0 Setting the data as experience data; if there is no empirical data, set S 0 =0; if the high-melting point metal is milled by the micro electric spark technique, S is set 0 >0。
Preferably, the online measurement step includes: the electrode wire and the guider execute the depth measurement movement of the tool starting point and the depth measurement movement of the tool retracting point on the part, and a compensation value is calculated;
the electrode wire and the guider execute the depth measuring movement of the knife starting point and the depth measuring movement of the knife retracting point, the depth of the tested cutting groove at the two positions is measured, and the processing depth compensation value delta Z and the electrode loss compensation relative speed S are calculated 1 The following are provided:
ΔZ＝h 10 -h 0
S 1 ＝S 0 +(h 10 -h 20 )/L
wherein: h is a 10 And h 20 Respectively isA measured value of the machining depth of the tool starting point and the tool retracting point, h 0 S is a set value of the processing depth 0 The relative rate was compensated for electrode loss in the pilot step.
Preferably, the correction trial cutting step includes: machining a correction test slot on the part by the electrode wire and the guide;
the electrode wire and the guide rotate at a high speed in the rotating direction, and from the corrected starting point, the electric spark milling is carried out on the part along the corrected feeding direction until the corrected retracting point is reached, so that the corrected trial cut groove is machined.
Preferably, in the correction trial cutting step, the new trial cutting is compared with the previous trial cutting, and the correction start point moves by delta Z towards the +Z direction; if ΔZ <0, the movement is in the-Z direction.
Preferably, the corrected feed direction is synthesized by a horizontal feed motion and an electrode loss compensation motion, wherein the horizontal feed distance is L, and the electrode loss compensation relative rate is S i I is the number of wheels for correcting trial cutting steps, and the compensation distance is S i L, direction is-Z.
Preferably, the modified online measurement step includes: the electrode wire and the guide device execute the depth measurement movement of the corrected tool starting point and the depth measurement movement of the corrected tool retracting point on the part, and a compensation value is calculated;
the electrode wire and the guider execute the depth measurement movement of the corrected starting point and the depth measurement movement of the corrected retracting point, the depth of the corrected test slot at the two positions is measured, and the machining depth compensation value delta Z and the electrode loss compensation relative speed S are calculated i+1 The following are provided:
ΔZ＝h 1i -h 0
S i+1 ＝S i +(h 1i -h 2i )/L
wherein: h is a 1i And h 2i Respectively the i-th wheel, namely the machining depth measured value of the corrected tool starting point and the corrected tool retracting point of the present wheel; h is a 0 Setting a value for the machining depth; s is S i Taking the electrode loss compensation relative speed of the correction trial cutting step of the round, S i+1 The electrode loss compensation relative rate of the trial cut step is corrected for the next round.
Compared with the prior art, the application has the following beneficial effects:
1. the application adopts the method of measuring the machining depth of electric spark milling on line and then adjusting the discharge gap according to the difference value of the measured depth and the set depth to correct the machining depth, and the process is closed-loop, thus the control precision of the machining depth of the electric spark milling starting point can be automatically ensured;
2. the method for measuring the electrode loss on line and iteratively calculating the electrode loss compensation relative speed is adopted, so that the consistency of the machining depth of the whole milling track can be automatically ensured;
3. the application allows electrode loss compensation to be carried out during primary trial cutting, solves the problem that the effective interval of electrode end surface discharge is extremely small under the condition of micro electric spark discharge so that continuous machining cannot be carried out after loss, and simultaneously ensures that the width of a machining track is consistent, thereby being particularly suitable for micro electric spark machining of high-melting-point metal;
4. on the basis of the three points, the electric spark milling depth can be automatically kept to be a set value, and the consistency of the machining process and the precision of the depth dimension of the part are ensured;
5. the application does not depend on a process database in the aspects of discharge gap setting and electrode loss compensation setting, and the system can automatically find reasonable parameters through trial cutting, online measurement and adjustment;
6. the application does not exclude related process data, and the reasonable set value of the discharge gap and the electrode loss compensation relative speed can accelerate the convergence process, and shortens the time of trial cutting, online measurement and adjustment.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
FIG. 1 is a schematic diagram of the spark milling process of the present application;
FIG. 2 is a schematic diagram of the spark milling pilot step of the present application;
FIG. 3 is a schematic view of an electric spark milling on-line measurement step cut-away according to the present application;
FIG. 4 is a schematic view of the spark milling correction pilot step of the present application;
FIG. 5 is a schematic view of the on-line measurement process step cut-away after the electric spark milling correction of the present application.
Reference numerals:
trial cutting step 1 on-line measurement step 2 correction trial cutting step 3
Modified electrode wire for online measurement step 4 and part 6 of guide 5
Tool withdrawal point 9 in tool feed direction 8 of tool start point 7
Depth measuring movement 15 of the start point 14 and the return point of the test slot 11
Corrected start point 16 corrected feed direction 17 corrected retract point 18
The rotation direction 19 corrects the horizontal feed movement 21 of the test slot 20
Depth measurement tool with electrode loss compensation motion 22 for correcting start point and correcting retract point
Move 23 move 24
Detailed Description
The present application will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present application, but are not intended to limit the application in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present application.
The embodiment of the application provides an electric spark milling method, which is shown by referring to fig. 1, and specifically comprises the following steps: trial cutting step 1, online measurement step 2, correction trial cutting step 3 and corrected online measurement step 4; the device also comprises a wire electrode 5, a part 6, a tool lifting point 7, a feed direction 8, a tool withdrawal point 9, a test slot 11, a depth measurement movement 14 of the tool lifting point, a depth measurement movement 15 of the tool withdrawal point, a correction tool lifting point 16, a correction feed direction 17, a correction tool withdrawal point 18, a correction test slot 20, a depth measurement movement 23 of the correction tool lifting point and a depth measurement movement 24 of the correction tool withdrawal point.
Firstly, executing a trial cutting step 1, starting from a starting point 7, performing electric spark milling on a part 6 along a feed direction 8 by using an electrode wire and a guide 5, and processing a trial cutting groove 11; then, an on-line measuring step 2 is carried out, and the machining depth compensation value delta Z and the electrode loss compensation relative speed S are measured and calculated 1 The method comprises the steps of carrying out a first treatment on the surface of the Then, a correction trial cutting step 3 is executed, a correction starting point 16 is calculated according to delta Z, and the electrode wire and the guide 5 complete a new trial cutting along a correction feed direction 17; next, a modified online measurement step 4 is performed to measure and calculate new rounds of ΔZ and S i (i=2, 3, …); if DeltaZ and S i If the frequency of the signal does not converge in the preset range, returning to the step 3 of executing the correction trial cutting; if the electric spark milling is converged, the subsequent electric spark milling is performed. In the milling process, the electrorule, the milling feed rate or the track superposition rate are changed, and the subsequent process steps are required to be executed again from the trial cutting process step 1.
In the trial cutting step 1, the electrode wire and the guider 5 are used for machining trial cuts 11 on the part 6; the wire electrode and the guide 5 are rotated at a high speed in a rotation direction 10, and the part 6 is subjected to spark milling in a feed direction 8 from a start point 7 to a withdrawal point 9, so that a test slot 11 is machined. The feed direction 8 is composed of a horizontal feed motion 12 and an electrode loss compensation motion 13, wherein the horizontal feed distance is L, and the electrode loss compensation relative speed is S 0 The compensation distance is S 0 L, direction is-Z. If there is empirical data of electrode loss compensation relative rate, then S is directly taken as 0 Setting the data as experience data; if there is no empirical data, set S 0 =0; if the high-melting point metal is milled by the micro electric spark technique, S is set 0 >0。
In the on-line measuring step 2, the wire electrode and the guide 5 perform a depth measuring movement 14 of the start point and a depth measuring movement 15 of the retract point on the part 6, and calculate the compensation value.
The electrode wire and the guide 5 execute the depth measuring movement 14 of the knife starting point and the depth measuring movement 15 of the knife retracting point, the depth of the tested cutting groove 11 at the two positions is measured, and the processing depth compensation value delta Z and the electrode loss compensation relative speed are calculatedS 1 The following are provided:
ΔZ＝h 10 -h 0
S 1 ＝S 0 +(h 10 -h 20 )/L
wherein: h is a 10 And h 20 The measured values of the machining depth, h, of the start point 7 and the relief point 9 respectively 0 S is a set value of the processing depth 0 The relative rate was compensated for electrode loss for trial cut step 1.
The correction trial cutting step 3 includes: the electrode wire and the guider 5 are used for machining a correction test slot 20 on the part 6; the wire electrode and the guide 5 are rotated at a high speed in a rotation direction 19, and starting from a correction start point 16, the part 6 is subjected to spark milling in a correction feed direction 17 to a correction retract point 18, and a correction test slot 20 is machined. The corrected start point 16 is moved by Δz in the +z direction (in the case where Δz <0, in the-Z direction) as compared with the previous trial cut.
The corrected feed direction 17 is composed of a horizontal feed motion 21 and an electrode loss compensation motion 22, wherein the horizontal feed distance is L, and the electrode loss compensation relative rate is S i (i is the number of rounds of correction trial cutting step 3, i=1, 2,3, …), the compensation distance is S i L, direction is-Z.
The corrected online measurement step 4 includes: the electrode wire and the guide 5 execute the depth measuring movement 23 of the corrected tool starting point and the depth measuring movement 24 of the corrected tool retracting point on the part 6, and calculate the compensation value;
the wire electrode and guide 5 performs a depth measuring movement 23 for correcting the start point and a depth measuring movement 24 for correcting the retract point, measures the depth of the corrected test slot 20 at the two positions, calculates a machining depth compensation value deltaz and an electrode loss compensation relative rate S i+1 The following are provided:
ΔZ＝h 1i -h 0
S i+1 ＝S i +(h 1i -h 2i )/L，(i＝1,2,3,…)
wherein: h is a 1i And h 2i The machining depth measurement values of the ith wheel, namely the corrected tool starting point 16 and the corrected tool retracting point 18 of the present wheel are respectively measured; h is a 0 Setting a value for the machining depth; s is S i Taking the electrode loss compensation relative speed of the correction trial cutting step of the round, S i+1 The electrode loss compensation relative rate of the trial cut step is corrected for the next round.
Next, the present application will be described in more detail.
The application provides an electric spark milling method, which comprises the following specific operation flows:
step S1: the wire electrode and the guide 5 are moved to a starting point 7 above the part 6, and the distance from the bottom surface of the wire electrode to the blank surface of the part 6 is smaller than the maximum discharge gap.
Step S2: the wire electrode and the guide 5 rotate at a high speed in a rotation direction 10, trial cutting of electric spark milling is started on the blank surface of the part 6, a horizontal feed motion 12 is started from a feed point 7, the horizontal feed distance is L (the feed track is not limited to a straight line), and a vertical downward electrode loss compensation motion 13 is performed on the servo shaft of the wire electrode and the guide 5, and the compensation speed is S 0 (in the field of micro electric spark milling of high melting point metals, S is recommended 0 >0) When the two movements are combined, the wire electrode and the guide 5 reach the retracting point 9 along the feeding direction 8, and the trial cutting groove 11 is processed.
Step S3: the depth measuring movement 14 of the electrode wire and the guide 5 as the start point and the depth measuring movement 15 of the retract point respectively measure the processing depth h at the start point 7 10 And the machining depth h at the tool withdrawal point 9 20 。
Step S4: calculating a machining depth compensation value Δz=h 10 -h 0 And electrode loss compensation relative rate S 1 ＝S 0 +(h 10 -h 20 ) and/L, wherein: h is a 0 Is a set value of the processing depth.
Step S5: the wire electrode and the guide 5 are moved to a start point 16 above the component 6, and the distance from the bottom surface of the wire electrode to the blank surface of the component 6 is Δz, which is +z (if Δz <0, the adjustment is performed in the-Z direction) as compared with the adjustment amount of the previous electric discharge machining.
Step S6: the wire electrode and the guide 5 are rotated at a high speed in a rotation direction 19, and the correction trial cutting of the spark milling is started on the blank surface of the part 6, and the horizontal feed is started from a start point 16The horizontal feed distance is L (feed track is not limited to straight line), and the electrode wire and the servo shaft of the guide 5 do electrode loss compensation movement 22 vertically downward, and the compensation speed is S i (i is the number of correction trial cutting steps 3, i=1, 2,3, …), and the two motions are combined, the wire electrode and the guide 5 reach the retracting point 18 along the feeding direction 17, and the trial cut 20 is machined.
Step S7: the depth measuring movement 23 of the electrode wire and the guide 5 as the start point and the depth measuring movement 24 of the retract point respectively measure the machining depth h at the corrected start point 16 of the ith round of correction trial cut 1i And correcting the machining depth h at the tool withdrawal point 18 2i 。
Step S8: calculating a machining depth compensation value Δz=h 1i -h 0 And electrode loss compensation relative rate S i+1 ＝S i +(h 1i -h 2i ) and/L, wherein: i=1, 2,3, …, h 1i And h 2i The machining depth measurements of the corrected start point 16 and the corrected retract point 18, respectively, S i Taking the electrode loss compensation relative speed of the trial cutting step of the round, S i+1 The relative rate is compensated for electrode loss for the next trial cut step.
Step S9: convergence condition DeltaZ is less than or equal to epsilon Z And |S i+1 -S i |≤ε S Wherein: epsilon Z And epsilon S The convergence domains of the relative rates are compensated for the machining depth and electrode loss, respectively. If the convergence condition is not satisfied, returning to the step S5 and the subsequent steps; if the convergence condition is satisfied, step S10 is performed.
Step S10: and performing subsequent electric spark milling.
Fig. 1 shows a process consisting of a trial cut step 1, an on-line measurement step 2, a corrected trial cut step 3, and a corrected on-line measurement step 4, which is performed in the direction of the arrows between the four steps.
First, trial cutting step 1 is performed. The wire electrode and the guide 5 are moved to a starting point 7 above the part 6, and the distance from the bottom surface of the wire electrode to the blank surface of the part 6 is smaller than the maximum discharge gap. The wire electrode and the guide 5 are rotated at a high speed in a rotation direction 10, and moved to a retracting point 9 in a feed direction 8, and a test slot 11 is machined.
And performing an online measurement step 2. The electrode wire and the guide 5 execute a depth measuring movement 14 of a start point and a depth measuring movement 15 of a withdrawal point, the depths of the test slots 11 at the two positions are measured, and a machining depth compensation value delta Z and an electrode loss compensation relative speed S are calculated 1 For the next trial cut.
Then, a correction trial cutting step 3 is performed. The wire electrode and the guide 5 are moved to a start point 16 above the part 6, the distance from the bottom surface of the wire electrode to the blank surface of the part 6 is delta Z compared with the adjustment amount of the last electric discharge machining, and the positive direction is the +Z direction. The wire electrode and the guide 5 are rotated at a high speed in a rotation direction 19, and moved in a feed direction 17 to a withdrawal point 18, and a correction test slot 20 is machined.
Then, the corrected online measurement step 4 is performed. The wire electrode and guide 5 performs a depth measuring movement 23 for correcting the start point and a depth measuring movement 24 for correcting the retract point, measures the depth of the corrected test slot 20 at the two positions, calculates a machining depth compensation value deltaz and an electrode loss compensation relative rate S i+1 For determining the convergence of the process parameters.
Convergence condition DeltaZ is less than or equal to epsilon Z And |S i+1 -S i |≤ε S Wherein: epsilon Z And epsilon S The convergence domains of the relative rates are compensated for the machining depth and electrode loss, respectively.
If the machining depth compensation value delta Z and the electrode loss compensation relative speed S i+1 Returning to the step 3 of executing the correction trial cutting if the convergence condition is not met, and using the parameters for a new trial cutting; if the convergence condition is satisfied, the convergence is performed according to the deltaZ and S i+1 And performing subsequent electric spark milling.
Fig. 2 shows the feeding state of the wire electrode and the guide 5 in the trial cutting step 1. The wire electrode and the guide 5 are moved to a starting point 7 above the part 6, and the distance from the bottom surface of the wire electrode to the blank surface of the part 6 is smaller than the maximum discharge gap.
The wire electrode and the guide 5 rotate at a high speed in a rotation direction 10, trial cutting of spark milling is started on the blank surface of the part 6, and a horizontal feed motion 12 and a horizontal feed distance are started from a tool starting point 7The distance is L (the feeding track is not limited to a straight line), and meanwhile, the electrode wire and the servo shaft of the guide 5 do electrode loss compensation movement 13 vertically downwards, and the compensation speed is S 0 (in the field of micro electric spark milling of high melting point metals, S is recommended 0 >0) The compensation distance is S 0 And L, combining the two movements into a feed direction 8, and enabling the electrode wire and the guide 5 to reach a tool withdrawal point 9 along the feed direction 8 to finish the processing of the test slot 11.
Fig. 3 shows the measurement of the machining depth of the advance and retreat point in the online measurement step 2. The wire electrode and guide 5 performs a depth measuring movement 14 of the start point and a depth measuring movement 15 of the retract point, measuring the depth of the test slot 11 at these two positions.
Calculating a machining depth compensation value delta Z and an electrode loss compensation relative speed S 1 The following are provided:
ΔZ＝h 10 -h 0 、S 1 ＝S 0 +(h 10 -h 20 )/L
wherein: h is a 10 And h 20 The measured values of the machining depth, h, of the start point 7 and the relief point 9 respectively 0 S is a set value of the processing depth 0 The relative rate was compensated for electrode loss for trial cut step 1.
Fig. 4 shows the feeding state of the wire electrode and the guide 5 in the correction trial cutting step 3. The wire and guide 5 are moved to a start point 16 above the part 6, which point is raised by a distance deltaz relative to the start point of the previous round of machining.
The wire electrode and the guide 5 rotate at a high speed in the rotation direction 19, a new trial cutting process of spark milling is started on the blank surface of the part 6, a horizontal feed motion 21 is started from the start point 16, the horizontal feed distance is L (the feed track is not limited to a straight line), and the wire electrode and the guide 5 perform a vertically downward electrode loss compensation motion 22 on the servo shaft, and the compensation speed is S i (i=1, 2,3, …) with a compensation distance S i L, the two movements are combined into a feed direction 17, and the wire electrode and the guide 5 reach a retracting point 18 along the feed direction 17, thereby completing the processing of the correction test slot 20.
Fig. 5 shows the measurement of the machining depth of the advance and retreat point in the corrected online measurement step 4. The wire electrode and guide 5 performs a depth measuring movement 23 of the corrected start point and a depth measuring movement 24 of the corrected retract point, and the depth of the corrected test slot 20 at these two positions is measured.
Calculating a machining depth compensation value delta Z and an electrode loss compensation relative speed S i+1 The following are provided:
ΔZ＝h 1i -h 0 、S i+1 ＝S i +(h 1i -h 2i )/L (i＝1,2,3,…)
wherein: h is a 1i And h 2i Machining depth measurements, h, of the i-th wheel (i.e., the present wheel) corrected start point 16 and corrected retract point 18, respectively 0 S is a set value of the processing depth i Taking the electrode loss compensation relative speed of the correction trial cutting step of the round, S i+1 The electrode loss compensation relative rate of the trial cut step is corrected for the next round.
The embodiment of the application provides an electric spark milling method, which adopts a method of measuring the machining depth of electric spark milling on line and then adjusting a discharge gap according to the difference value between the measured depth and the set depth to correct the machining depth, and the process can automatically ensure the control precision of the machining depth of an electric spark milling starting point; the method for measuring the electrode loss on line and iteratively calculating the electrode loss compensation relative speed is adopted, so that the consistency of the machining depth of the milling track can be automatically ensured; the application allows electrode loss compensation to be performed during primary trial cutting, solves the problem that the effective interval of electrode end surface discharge is extremely small so as not to be continuously processed under the discharge condition of micro electric spark processing high-melting point metal, and simultaneously ensures that the width of a processing track is consistent; on the basis of the three points, the electric spark milling depth can be automatically kept to be a set value, and the consistency of the machining process and the precision of the depth dimension of the part are ensured; the application does not depend on a process database in the aspects of discharge gap setting and electrode loss compensation setting, and the system can automatically find reasonable parameters through trial cutting, online measurement and adjustment; the application does not exclude related process data, and the reasonable set value of the discharge gap and the electrode loss compensation relative speed can accelerate the convergence process, and shortens the time of trial cutting, online measurement and adjustment.
Those skilled in the art will appreciate that the application provides a system and its individual devices, modules, units, etc. that can be implemented entirely by logic programming of method steps, in addition to being implemented as pure computer readable program code, in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. Therefore, the system and various devices, modules and units thereof provided by the application can be regarded as a hardware component, and the devices, modules and units for realizing various functions included in the system can also be regarded as structures in the hardware component; means, modules, and units for implementing the various functions may also be considered as either software modules for implementing the methods or structures within hardware components.
The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.
Claims (4)
1. A method of spark milling comprising: a trial cutting step (1), an online measurement step (2), a correction trial cutting step (3) and a corrected online measurement step (4);
wherein, the trial cutting step (1): comprises an electrode wire, a guide (5), a tool starting point (7), a tool feeding direction (8), a part (6) and a test cutting groove (11); starting from a cutting start point (7), the electrode wire and the guide (5) perform electric spark milling on the part (6) along a cutting feed direction (8), process a test slot (11) and then execute an online measurement step (2);
on-line measurement step (2): measuring and calculating a machining depth compensation value delta Z and an electrode loss compensation relative rate S 1 ；
The online measurement step (2) includes: the electrode wire and the guider (5) execute depth measurement movement (14) of a tool starting point and depth measurement movement (15) of a tool retracting point on the part (6), and a compensation value is calculated;
the electrode wire and the guider (5) execute the depth measuring movement (14) of the knife starting point and the depth measuring movement (15) of the knife withdrawing point, the depth of the test slot (11) at the two positions is measured, and the processing depth compensation value delta Z and the electrode loss compensation relative speed S are calculated 1 The following are provided:
ΔZ=h 10 -h 0
S 1 =S 0 +(h 10 -h 20 )/L
wherein: h is a 10 And h 20 The measured values of the machining depth of the tool starting point (7) and the tool retracting point (9) are respectively h 0 S is a set value of the processing depth 0 Compensating the relative rate for electrode loss in trial cutting step (1);
correction trial cutting step (3): comprises a corrected starting point (16) and a corrected feed direction (17); calculating a correction starting point (16) according to the delta Z, and finishing a new trial cutting along a correction feeding direction (17) by the electrode wire and the guide (5);
and (3) a corrected online measurement step (4): measuring and calculating a new round of deltaz and S i (i=2, 3, …); if DeltaZ and S i If the frequency is not converged in the preset range, returning to the correction trial cutting step (3); if the electric spark milling is converged, carrying out subsequent electric spark milling;
the corrected online measurement step (4) includes: the electrode wire and the guide (5) execute a depth measuring movement (23) for correcting the starting point and a depth measuring movement (24) for correcting the withdrawal point on the part (6) to calculate a compensation value;
the wire electrode and the guide (5) execute a depth measuring movement (23) for correcting the start point and a depth measuring movement (24) for correcting the withdrawal point, the depths of the corrected test slot (20) at the two positions are measured, and a machining depth compensation value delta Z and an electrode loss compensation relative speed S are calculated i+1 The following are provided:
ΔZ=h 1i -h 0
S i+1 =S i +(h 1i -h 2i )/L
wherein: h is a 1i And h 2i The machining depth measurement values of the ith wheel, namely the corrected tool starting point (16) and the corrected tool retracting point (18) of the present wheel are respectively measured; h is a 0 Setting a value for the machining depth; l is the horizontal feed distance; s is S i Taking the electrode loss compensation relative speed of the correction trial cutting step of the round, S i+1 The electrode loss compensation relative rate of the trial cut step is corrected for the next round.
2. The electric spark milling method according to claim 1, characterized in that the wire electrode and the guide (5) in the pilot cutting step (1) machine pilot cuts (11) in the part (6);
the electrode wire and the guide (5) rotate at a high speed in a rotating direction (10), and the part (6) is subjected to electric spark milling from a tool starting point (7) to a tool retracting point (9) along a tool feeding direction (8), so as to process a test slot (11);
the feed direction (8) is composed of a horizontal feed motion (12) and an electrode loss compensation motion (13), wherein the horizontal feed distance is L, and the electrode loss compensation relative speed is S 0 The compensation distance is S 0 L, direction is-Z.
3. The spark-milling method of claim 2 wherein if there is empirical data on the relative rate of electrode loss compensation, then directly comparing S 0 Setting the data as experience data; if there is no empirical data, set S 0 =0; if the high-melting point metal is milled by the micro electric spark technique, S is set 0 >0。
4. The electric spark milling method according to claim 1, wherein the modified pilot cutting step (3) comprises: machining a correction test slot (20) on the part (6) by the electrode wire and the guide (5);
the electrode wire and the guide (5) rotate at a high speed in a rotating direction (19), and starting from a correction starting point (16), the electric spark milling is carried out on the part (6) along a correction feeding direction (17) until a correction retracting point (18) is reached, and a correction test slot (20) is machined;
in the correction trial cutting step (3), compared with the previous trial cutting, a new trial cutting is performed, and the correction starting point (16) moves by delta Z towards the +Z direction; if ΔZ <0, then move in the-Z direction;
the corrected feed direction (17) is composed of a horizontal feed motion (21) and an electrode loss compensation motion (22), wherein the horizontal feed distance is L, and the electrode loss compensation relative speed is S i I is the number of wheels of the correction trial cutting step (3), and the compensation distance is S i L, direction is-Z.
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