A control system and method of a precision automatic multi-axis numerical control electric spark forming machine

Abstract

The application discloses a kind of control system and method of precision automatic multi-axis numerical control electric spark forming machine, it is related to the technical field of electric spark forming machine, the system includes: motion control module, for controlling the initial interface of electrode execution open discharge interface detection process determination of electric spark forming machine, control electrode is located initial interface;Flushing control module, for responding to the initial interface detected, control working fluid flows at first speed in first time interval, and flows at second speed in second time interval after first time interval, flush the metal particle generated by metal material, first speed is greater than second speed, in open discharge interface detection process, working fluid flows at second speed;Discharge detection module, for responding to the end of first time interval, if detecting the discharge of electrode in second time interval, then initial interface is determined as open discharge interface.The application improves the accuracy of open discharge interface determination.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric spark forming machines, in particular to a control system and method of a precise automatic multi-axis numerical control electric spark forming machine. BACKGROUND

[0002] Electric spark machining is a method of processing materials by using the electric corrosion phenomenon generated by pulse discharge between electrodes. Studies have shown that during the discharge between two electrodes, a large amount of heat is generated in the discharge channel, which is sufficient to locally melt or vaporize the surface of the electrode material, and under certain conditions, the melted or vaporized part can be thrown away from the surface of the electrode to form a crater of electric discharge corrosion. The process of repeated pulse discharge in a liquid medium can process the size of conductive materials, i.e. electric spark machining method.

[0003] A Chinese patent with publication number "CN103240474B" discloses a discharge gap control method for electric spark machining equipment. The method continuously detects the "open circuit discharge interface" to ensure that the electrode is as much as possible in the "normal discharge gap range" to achieve the highest efficient processing speed. The processing effect is controlled by controlling the depth of the electrode in the "discharge gap range". When necessary, the depth of the "discharge gap range" can be tested by detecting the positions of the "open circuit discharge interface" and "short circuit". That is, the above-mentioned method takes the open circuit discharge interface as the distinguishing reference. The movement in the Z-axis direction and the discharge detection are performed above the reference surface. The processing is performed below the reference surface and closer to the metal piece to be processed.

[0004] In the above-mentioned technology, the moment when the current reaching the discharge current size flows in the discharge circuit is considered as the starting moment of the "discharge state". The result of the execution is that the electrode "stops" for Δt time. The moment when no "discharge" is detected in the Δt time before the "discharge state" or after a discharge in the "discharge state" is the starting moment of the "open circuit state". The result of the execution is that the electrode maintains a constant speed Va to approach the workpiece.

[0005] However, the working liquid of the electric spark forming machine floats a large number of metal particles during the processing process. The current position is easily confirmed as the open circuit discharge interface in the case of discharge caused by metal particles. Then, the erroneously confirmed open circuit discharge interface is further identified as the real open circuit discharge interface because of the discharge behavior under another metal particle in the Δt time.

[0006] Especially for the multi-cow head processing electric spark forming machine tool, such as the six-cow head electric spark forming machine tool disclosed in the Chinese patent with the publication number "CN223114310U", the misjudgment caused by metal particle interference will form a processing blind area between the virtual boundary and the real workpiece, which may cause size precision out-of-tolerance or even trigger a chain damage of the equipment.

[0007] Therefore, how to improve the accuracy of open-circuit discharge boundary determination has become a technical problem to be solved. SUMMARY

[0008] The technical problem solved by the present application is to improve the accuracy of open-circuit discharge boundary determination.

[0009] To solve the above technical problems, the present application provides the following technical solutions: in a first aspect, 1. A control system of a precision automatic multi-axis numerical control electric spark forming machine, characterized in that it comprises:

[0010] A motion control module for controlling the electrode of the electric spark forming machine to perform an open-circuit discharge boundary detection process to determine an initial boundary, and controlling the electrode to be located at the initial boundary.

[0011] A flushing control module for controlling the working fluid to flow at a first speed within a first time interval and at a second speed within a second time interval after the first time interval in response to detecting the initial boundary, to flush the metal particles generated by the metal material, the first speed being greater than the second speed, wherein the working fluid flows at the second speed during the open-circuit discharge boundary detection process.

[0012] A discharge detection module for determining the initial boundary as the open-circuit discharge boundary if the discharge of the electrode is detected within the second time interval in response to the end of the first time interval.

[0013] The control system further comprises:

[0014] A flow rate determination module for:

[0015] Reading the metal density of the metal material, the liquid density of the working fluid, the fluid dynamic viscosity of the working fluid, the second speed of the working fluid, and the processing stage of the electric spark forming machine in the first time interval.

[0016] Reading the particle diameter according to the processing stage.

[0017] Determining the natural settling velocity according to the metal density, the liquid density, the fluid dynamic viscosity, and the particle diameter.

[0018] The drag force of the working fluid on the metal particles is characterized by the minimum flow rate, the natural settling velocity, the hydrodynamic viscosity, and the particle diameter.

[0019] Based on the inequality that the drag force is greater than or equal to the difference between the gravity and buoyancy of the metal particles, the minimum value of the minimum flow velocity is determined to obtain the first minimum flow velocity.

[0020] The first upper limit velocity is determined based on the Reynolds number constraint condition based on the laminar critical Reynolds number;

[0021] The second upper limit flow rate is determined based on the preset dielectric film stability conditions;

[0022] The smaller of the first upper limit flow velocity and the second upper limit flow velocity is determined as the maximum flow velocity value, and the larger of the first minimum flow velocity and the second velocity is determined as the minimum flow velocity value;

[0023] The first velocity is determined from the range of the lowest flow velocity value to the highest flow velocity value;

[0024] The determination of the first upper limit flow velocity based on the Reynolds number constraint condition based on the laminar critical Reynolds number includes:

[0025] Read the Reynolds number constraint value, which is used to characterize the maximum Reynolds number under laminar flow conditions;

[0026] The expected Reynolds number is characterized by the liquid density, the first velocity, and the hydrodynamic viscosity.

[0027] The maximum value of the first velocity is obtained by solving the inequality that the expected Reynolds number is less than or equal to the Reynolds number constraint number.

[0028] Preferably, determining the second upper limit flow rate based on the preset dielectric film stability condition includes:

[0029] Read the first height of the upper surface of the metal material and the second height of the electrode;

[0030] The gap data between the electrode and the metal material is determined based on the first height and the second height.

[0031] Read the surface tension of the dielectric fluid formed by the working fluid;

[0032] The second upper limit flow rate is determined based on the liquid density, the gap data, and the dielectric fluid surface tension.

[0033] Preferably, determining the first velocity from the range of the lowest flow velocity value to the highest flow velocity value includes:

[0034] Obtain the discharge state of multiple electrodes of the CNC EDM machine;

[0035] The first velocity is determined from the range of the lowest flow rate value to the highest flow rate value based on the discharge state of the plurality of electrodes.

[0036] Preferably, the control system further includes:

[0037] The timing determination module is used for:

[0038] Read the volume data and target concentration data of the metal material;

[0039] The first differential equation is established based on the differential terms of particle concentration and time, as well as the concentration.

[0040] The left side of the second differential equation is determined by multiplying the differential terms of particle concentration and time with the volume data, and the right side of the second differential equation is determined by the fluid flow rate, the inflow particle concentration, and the target particle concentration, thus obtaining the second differential equation.

[0041] Solving the second differential equation yields the characterization of the target particle concentration, which is characterized by the inflow particle concentration, the initial particle concentration in the metal material region, time, the fluid flow rate of the working fluid, and the volume data.

[0042] Based on the inequality that the target particle concentration is less than or equal to the target concentration data, the minimum value of the time is determined, and the characterization formula of the time is obtained;

[0043] The first time interval is determined according to the time representation formula.

[0044] Preferably, the flow timing determination module is further configured to:

[0045] Obtain the filling height of the working fluid;

[0046] Read the flow width of the electrical discharge machining (EDM) machine;

[0047] The cross-sectional area of ​​the working fluid is determined based on the filling height and the flow width;

[0048] The fluid flow rate is determined based on the first velocity and the cross-sectional area.

[0049] Preferably, the CNC EDM machine further includes:

[0050] The concentration statistics module is used for:

[0051] In response to the detection of the initial interface, a target image of the working fluid containing the metal material is captured, and the initial particle concentration is determined based on the pixel values ​​of the working fluid in the target image and the pixel values ​​of the metal material in the target image.

[0052] The concentration of the incoming particles is estimated based on the positional relationship between the multiple electrodes of the CNC EDM machine and the discharge state of the multiple electrodes.

[0053] Preferably, the time representation further includes a correction factor, which is negatively correlated with the time and positively correlated with the particle diameter.

[0054] Secondly, a control method for a precision automatic multi-axis CNC electrical discharge machining (EDM) machine is provided, including:

[0055] The electrodes of the electrical discharge machining machine are controlled to perform an open-circuit discharge interface detection process to determine the initial interface;

[0056] The control electrode is located at the initial interface;

[0057] The working fluid is controlled to flow at a first speed during a first time interval and at a second speed during a second time interval after the first time interval, to flush metal particles generated by the metal material. The first speed is greater than the second speed. During the open-circuit discharge interface detection process, the working fluid flows at the second speed.

[0058] In response to the end of the first time interval, if discharge of the electrode is detected during the second time interval, the initial interface is determined as the open-circuit discharge interface.

[0059] The beneficial effects of this invention are as follows: By controlling the electrodes of the EDM machine to perform an open-circuit discharge interface detection process to determine the initial interface, controlling the electrodes to be located at the initial interface to form an initial time of electrode stillness, and controlling the working fluid to flow at a first speed in the first time interval and at a second speed in the second time interval after the first time interval to flush away the metal particles generated by the metal material, the electrode stillness is divided into the flushing time of the working fluid flushing the metal particles and the discharge verification detection time. This avoids as much as possible the situation where the accuracy of the open-circuit discharge interface determination is low due to the continuous interference of metal particles with the determination of the initial interface and the discharge verification detection, thereby improving the accuracy of the open-circuit discharge interface determination. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the basic structure of the control system of a precision automatic multi-axis CNC EDM machine provided in one embodiment of the present invention. Detailed Implementation

[0061] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0062] Example 1, referring to Figure 1 As an embodiment of the present invention, a control system for a precision automatic multi-axis CNC electrical discharge machining (EDM) machine is provided, comprising:

[0063] The motion control module is used to control the electrodes of the EDM machine to perform an open-circuit discharge interface detection process to determine the initial interface and control the electrodes to be located at the initial interface.

[0064] The flushing control module is used to control the working fluid to flow at a first speed during a first time interval and at a second speed during a second time interval after the first time interval in response to the detection of the initial interface, so as to flush the metal particles generated by the metal material. The first speed is greater than the second speed. During the open-circuit discharge interface detection process, the working fluid flows at the second speed.

[0065] The discharge detection module is used to determine the initial interface as an open-circuit discharge interface if the discharge of the electrode is detected during the second time interval in response to the end of the first time interval.

[0066] The open-circuit discharge interface detection process can be found in the description of the detection process in the reference patent with authorization announcement number "CN103240474B", which will not be repeated here. The open-circuit discharge interface determined in the reference patent is the initial interface described in the embodiments of this application. The second time interval in this application corresponds to Δt in the reference patent. That is, the reference patent defines that before the time point when "discharge" is detected, it is an "open-circuit state"; the start time of the "discharge state" is the time point when "discharge" is detected; when "discharge" is detected, "discharge" must occur again within the time interval Δt; during the "discharge state", if no discharge occurs within Δt, the state changes to an "open-circuit state" at the end of Δt; the start time of the "open-circuit state" is also the end time of the "discharge state", and at the same time, the electrode exits the "open-circuit discharge interface" and enters the open-circuit gap range. This application, after detecting the occurrence of a "discharge", adds a first time interval within a time interval of Δt (the second time interval of this application) before detecting the recurrence of a "discharge", and controls the working fluid to flow at a first speed within the first time interval to flush away the metal particles generated by the metal material.

[0067] For the second speed, you can refer to the technical content in the patent for corresponding settings.

[0068] For determining the first velocity, preferably, the control system further includes a velocity determination module, used for: reading the metal density of the metal material, the liquid density of the working fluid, the hydrodynamic viscosity of the working fluid, the second velocity of the working fluid, and the processing stage of the EDM machine in the first time interval; reading the particle diameter according to the processing stage; determining the natural settling velocity according to the metal density, liquid density, hydrodynamic viscosity, and particle diameter; characterizing the drag force of the working fluid on the metal particles according to the minimum velocity, natural settling velocity, hydrodynamic viscosity, and particle diameter; determining the minimum value of the minimum velocity based on the inequality that the drag force is greater than or equal to the difference between the gravity and buoyancy of the metal particles, thus obtaining the first minimum velocity; determining the first upper limit velocity according to the Reynolds number constraint condition based on the laminar critical Reynolds number; determining the second upper limit velocity according to the preset dielectric film stability condition; determining the smaller of the first upper limit velocity and the second upper limit velocity as the maximum velocity value, and determining the larger of the first minimum velocity and the second velocity as the minimum velocity value; and determining the first velocity from the range of the minimum velocity value to the maximum velocity value.

[0069] The determination of the first upper limit velocity based on the Reynolds number constraint condition based on the laminar critical Reynolds number includes: reading the Reynolds number constraint value, which is used to characterize the maximum value of the Reynolds number under laminar conditions; characterizing the expected Reynolds number based on the liquid density, the first velocity, and the hydrodynamic viscosity; and solving for the maximum value of the first velocity based on the inequality that the expected Reynolds number is less than or equal to the Reynolds number constraint number to obtain the first upper limit velocity.

[0070] The process of determining the second upper limit flow rate based on preset dielectric film stability conditions includes: reading the first height of the upper surface of the metal material and the second height of the electrode; determining the gap data between the electrode and the metal material based on the first height and the second height; reading the surface tension of the dielectric fluid formed by the working fluid; and determining the second upper limit flow rate based on the liquid density, gap data, and dielectric fluid surface tension.

[0071] First, based on the mechanical equilibrium (gravity = buoyancy + Stokes drag) of a spherical particle reaching its terminal velocity in an infinitely large, still fluid, the natural settling velocity of the particle in the still fluid is calculated. This settling velocity is then used as the baseline resistance that the fluid must overcome. Specifically,

[0072] .

[0073] The natural settlement rate, For metal density, For the density of the liquid, It is the acceleration due to gravity. The particle diameter is This refers to the fluid dynamic viscosity.

[0074] in, The particle diameter d can be corrected based on morphological parameters. For example, the construction method, system, and medium for calculating the settling drag force coefficient of irregularly shaped particles disclosed in Chinese Patent Publication No. CN118410690A are used for experimental calibration to determine the typical particle diameter corresponding to metal debris particles. The calibrated typical particle diameter is then used to calculate the natural settling velocity in practice. Furthermore, the electrical characteristics of the electrodes can be used to distinguish whether the electrodes are in the roughing or fine processing stage. The diameter of metal particles in the roughing stage is larger than that of metal particles in the fine processing stage.

[0075] Secondly, the original formula This only describes the particle settling velocity; in practice, the minimum first flow velocity that the fluid needs to reach must be calculated in reverse. Only when the minimum flow rate is reached can metal particles be flushed away. At that time, the drag force of the fluid on the particles Greater than the difference between the particle's weight and buoyancy ( ), This represents the fluid velocity.

[0076] Drag force formula (modified Stokes force, considering flow direction):

[0077] .

[0078] Conditions for being swept away ( ):

[0079] .

[0080] Substitution And solve :

[0081] .

[0082] Therefore,

[0083] .

[0084] Furthermore, excessively high flow rates can lead to instability of the dielectric film between the electrode and the workpiece (causing short circuits), a change in flow from laminar to turbulent (debris redeposition), and a dramatic increase in energy consumption (pumping power is proportional to the cube of the flow rate). Therefore, the flow rate must be limited below the critical Reynolds number for laminar flow while satisfying the dielectric film stability requirements.

[0085] Reynolds number constraints (laminar flow conditions) ):

[0086] .

[0087] in, The hydraulic diameter of the flow channel and the typical value of the EDM gap are given. .

[0088] Under the Reynolds number constraint, solving for the first upper limit velocity yields:

[0089] .

[0090] In addition, the stability of the dielectric liquid film is constrained (according to experimental empirical formulas). Excessive flow velocity will break the liquid film between the electrode and the workpiece; the critical flow velocity... (Second upper limit flow rate) and gap Related:

[0091] .

[0092] in, , The surface tension of the dielectric fluid (typical value 0.02 ~ 0.03 N / m), It can be determined based on the motion records of the electrodes.

[0093] The first upper limit (Reynolds number constraint) ensures that the fluid flow is in a laminar state, as turbulence can interfere with the stability of the discharge and produce unpredictable processing results. The second upper limit (dielectric film stability) is that excessively high flow velocities can damage the dielectric film formed on the electrode and workpiece surfaces, which is crucial for the discharge process. Taking the smaller of the two as the upper limit ensures both processing stability and discharge process stability.

[0094] The process of determining the first velocity from the lowest to the highest flow rate includes: acquiring the discharge states of multiple electrodes of the CNC EDM machine; and determining the first velocity from the lowest to the highest flow rate based on the discharge states of the multiple electrodes. The magnitude of debris generation corresponding to the basic forms of the discharge states of a single pulse waveform during EDM can be determined based on these basic forms. Then, based on the magnitude of debris generation corresponding to the basic forms of the discharge states and the relationship between the upstream and downstream flow of the working fluid, the range from the lowest to the highest flow rate is selected in a stepped manner. The basic forms include: "normal discharge," "transitional arc" (recoverable unstable arc), "arc discharge," "short circuit," and "open circuit" (no load).

[0095] For determining the first time interval, preferably, the control system further includes a flow time determination module, used to read the volume data and target concentration data of the metal material; establish a first differential equation based on the differential terms of particle concentration and time, and concentration; determine the left side of the second differential equation based on the product of the differential terms of particle concentration and time and volume data, and determine the right side of the second differential equation based on fluid flow rate, inflow particle concentration, and target particle concentration, thus obtaining the second differential equation; solve the second differential equation to obtain the characterization of the target particle concentration, which is characterized by the inflow particle concentration, the initial particle concentration of the metal material area, time, fluid flow rate of the working fluid, and volume data; determine the minimum value of time based on the inequality that the target particle concentration is less than or equal to the target concentration data, thus obtaining the characterization of time; and determine the first time interval according to the characterization of time.

[0096] The time representation also includes a correction factor, which is negatively correlated with time and positively correlated with particle diameter.

[0097] First, particle removal rate With concentration Proportional:

[0098] .

[0099] This describes the exponential decay of particle concentration within a target area when no external particles flow in. Based on first-order kinetics, the particle removal rate is directly proportional to the current concentration, with a negative sign indicating that the concentration decreases over time.

[0100] The target workpiece does not generate particles, but particles generated by other workpieces will flow into the target area via the fluid. The model needs to be modified to consider both inflow (external particles flowing into the target area at a constant concentration) and outflow (particles in the target area being carried out by the fluid at a certain rate).

[0101] Based on the mass balance equation, let the volume of the target region be... (m³), fluid flow rate is (m³ / s).

[0102] The changes in particle mass per unit time include:

[0103] , Indicates the amount of particles flowing in. This indicates the amount of particles flowing out.

[0104] Solving the differential equation yields:

[0105] .

[0106] (kg / m³) represents the concentration of inflow particles generated by other metal processing parts. Specifically, the concentration of inflow particles is estimated based on the positional relationship between multiple electrodes of the CNC EDM machine and the discharge state of the multiple electrodes. In other words, it can be based on empirical data obtained from experiments.

[0107] , is the clearance rate coefficient ( ).

[0108] in, The determination process includes: obtaining the filling height of the working fluid, reading the flow width of the EDM machine, determining the cross-sectional area of ​​the working fluid based on the filling height and flow width, and determining the fluid flow rate based on the first velocity and cross-sectional area.

[0109] in, The volume of the metal material input manually.

[0110] Furthermore, to increase the concentration , Given a concentration threshold, under constraints, solve the inequality:

[0111] .

[0112] Constraints: The initial concentration was higher than the inflow concentration; The threshold must be higher than the inflow concentration; otherwise, it cannot be achieved.

[0113] The solution yields:

[0114] .

[0115] In other words, to get the shortest time.

[0116] The removal efficiency differs between coarse processing (large particles) and fine processing (small particles). Large particles are easily settled / carried away by the fluid, resulting in faster removal. > 1); Small particles, strong suspension, slow removal ( < 1). A size correction factor needs to be introduced into β. ,get:

[0117] .

[0118] roughing, Fine processing .

[0119] For the concentration parameter, preferably, the CNC EDM machine also includes a concentration statistics module, used to: in response to the detection of the initial interface, capture a target image of the working fluid containing the metal material, and determine the initial particle concentration based on the pixel values ​​of the working fluid and the pixel values ​​of the metal material in the target image.

[0120] The initial particle concentration can be reflected by the pigment distribution in the working fluid, that is, the concentration can be determined by the pixel distribution and specific pixel values ​​based on machine vision. The pigment of the metal material is used as a reference pigment to improve the accuracy of concentration prediction.

[0121] On the other hand, a control method for a precision automatic multi-axis CNC EDM machine is also provided. The control method corresponds to several embodiments of the above system and will not be described in detail here.

[0122] This application embodiment determines the initial interface by controlling the electrodes of the EDM machine to perform an open-circuit discharge interface detection process. The electrodes are controlled to be located at the initial interface to form an initial period of electrode stillness. The working fluid is controlled to flow at a first speed during a first time interval and at a second speed during a second time interval after the first time interval to flush away metal particles generated by the metal material. This divides the electrode stillness into the flushing time of the working fluid flushing the metal particles and the discharge verification detection time, thereby avoiding the situation where the accuracy of the open-circuit discharge interface determination is low due to continuous interference of metal particles in the determination of the initial interface and the discharge verification detection, thus improving the accuracy of the open-circuit discharge interface determination.

[0123] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media containing computer-usable program code. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0124] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A control system for a precision automatic multi-axis CNC electrical discharge machining (EDM) machine, characterized in that, include: The motion control module is used to control the electrodes of the EDM machine to perform an open-circuit discharge interface detection process to determine the initial interface and to control the electrodes to be located at the initial interface. A flushing control module is used to control the working fluid to flow at a first speed during a first time interval and at a second speed during a second time interval after the first time interval in response to the detection of the initial interface, so as to flush the metal particles generated by the metal material. The first speed is greater than the second speed. During the open-circuit discharge interface detection process, the working fluid flows at the second speed. The discharge detection module is configured to, in response to the end of the first time interval, if discharge of the electrode is detected during the second time interval, determine the initial interface as an open-circuit discharge interface. The control system further includes: The flow rate determination module is used for: The metal density of the metal material, the liquid density of the working fluid, the hydrodynamic viscosity of the working fluid, the second velocity of the working fluid, and the processing stage of the EDM machine during the first time interval are read. The particle diameter is read according to the processing stage; The natural settling velocity is determined based on the metal density, the liquid density, the hydrodynamic viscosity, and the particle diameter. The drag force of the working fluid on the metal particles is characterized by the minimum flow rate, the natural settling velocity, the hydrodynamic viscosity, and the particle diameter. Based on the inequality that the drag force is greater than or equal to the difference between the gravity and buoyancy of the metal particles, the minimum value of the minimum flow velocity is determined to obtain the first minimum flow velocity. The first upper limit velocity is determined based on the Reynolds number constraint condition based on the laminar critical Reynolds number; The second upper limit flow rate is determined based on the preset dielectric film stability conditions; The smaller of the first upper limit flow velocity and the second upper limit flow velocity is determined as the maximum flow velocity value, and the larger of the first minimum flow velocity and the second velocity is determined as the minimum flow velocity value; The first velocity is determined from the range of the lowest flow velocity value to the highest flow velocity value; The determination of the first upper limit flow velocity based on the Reynolds number constraint condition based on the laminar critical Reynolds number includes: Read the Reynolds number constraint value, which is used to characterize the maximum Reynolds number under laminar flow conditions; The expected Reynolds number is characterized by the liquid density, the first velocity, and the hydrodynamic viscosity. The maximum value of the first velocity is obtained by solving the inequality that the expected Reynolds number is less than or equal to the Reynolds number constraint number.

2. The control system of a precision automatic multi-axis CNC EDM forming machine as described in claim 1, characterized in that, The step of determining the second upper limit flow rate based on the preset dielectric film stability condition includes: Read the first height of the upper surface of the metal material and the second height of the electrode; The gap data between the electrode and the metal material is determined based on the first height and the second height. Read the surface tension of the dielectric fluid formed by the working fluid; The second upper limit flow rate is determined based on the liquid density, the gap data, and the dielectric fluid surface tension.

3. The control system of a precision automatic multi-axis CNC EDM forming machine as described in claim 2, characterized in that, Determining the first velocity from the range of the lowest flow velocity value to the highest flow velocity value includes: Obtain the discharge state of multiple electrodes of the CNC EDM machine; The first velocity is determined from the range of the lowest flow rate value to the highest flow rate value based on the discharge state of the plurality of electrodes.

4. The control system of a precision automatic multi-axis CNC EDM forming machine as described in claim 3, characterized in that, The control system further includes: The timing determination module is used for: Read the volume data and target concentration data of the metal material; The first differential equation is established based on the differential terms of particle concentration and time, as well as the concentration. The left side of the second differential equation is determined by multiplying the differential terms of particle concentration and time with the volume data, and the right side of the second differential equation is determined by the fluid flow rate, the inflow particle concentration, and the target particle concentration, thus obtaining the second differential equation. Solving the second differential equation yields the characterization of the target particle concentration, which is characterized by the inflow particle concentration, the initial particle concentration in the metal material region, time, the fluid flow rate of the working fluid, and the volume data. Based on the inequality that the target particle concentration is less than or equal to the target concentration data, the minimum value of the time is determined, and the characterization formula of the time is obtained; The first time interval is determined according to the time representation formula.

5. The control system of a precision automatic multi-axis CNC EDM forming machine as described in claim 4, characterized in that, The timing determination module is also used for: Obtain the filling height of the working fluid; Read the flow width of the electrical discharge machining (EDM) machine; The cross-sectional area of ​​the working fluid is determined based on the filling height and the flow width; The fluid flow rate is determined based on the first velocity and the cross-sectional area.

6. The control system of a precision automatic multi-axis CNC EDM forming machine as described in claim 5, characterized in that, The CNC EDM forming machine also includes: The concentration statistics module is used for: In response to the detection of the initial interface, a target image of the working fluid containing the metal material is captured, and the initial particle concentration is determined based on the pixel values ​​of the working fluid in the target image and the pixel values ​​of the metal material in the target image. The concentration of the incoming particles is estimated based on the positional relationship between the multiple electrodes of the CNC EDM machine and the discharge state of the multiple electrodes.

7. The control system of a precision automatic multi-axis CNC EDM forming machine as described in claim 6, characterized in that, The time representation also includes a correction factor, which is negatively correlated with the time and positively correlated with the particle diameter.

8. A control method for a precision automatic multi-axis CNC electrical discharge machining (EDM) machine, which is applied to the control system of a precision automatic multi-axis CNC EDM machine as described in any one of claims 1-7, characterized in that, include: The electrodes of the electrical discharge machining machine are controlled to perform an open-circuit discharge interface detection process to determine the initial interface; The electrode is positioned at the initial interface; The working fluid is controlled to flow at a first speed during a first time interval and at a second speed during a second time interval after the first time interval to flush metal particles generated by the metal material. The first speed is greater than the second speed. During the open-circuit discharge interface detection process, the working fluid flows at the second speed. In response to the end of the first time interval, if discharge of the electrode is detected during the second time interval, the initial interface is determined as an open-circuit discharge interface.

Images