An adaptive mixed-powder assisted electric discharge machining system and method

Abstract

The application discloses a kind of adaptive mixed powder auxiliary electric spark machining system and method, including executing electric spark machining, and the processing subsystem of composite processing liquid injection into processing gap;According to the need of working condition, different particle size of mixed powder is selected, and composite processing liquid is formed by mixing with processing liquid clear liquid according to preset ratio;Mixed powder and working liquid clear liquid in waste liquid are separated, and recycling is recycled to the filtering subsystem of mixed powder subsystem;Mixed powder subsystem includes double-drive stirring mechanism, centrifugal force is generated by mechanical stirring, and the rotational flow stirring is formed by centrifugal force driving and pump liquid driving cooperation, rotational flow stirring and mechanical stirring cooperate, form the space circulation stirring flow along the axis of mechanical stirring shaft.The application cooperates with adaptive liquid supplement and adaptive double-drive stirring, enhances uniformity while effectively shortening non-uniform window period, to solve the contradiction between continuous processing production and mixed powder uniformity maintenance.

Description

Technical Field

[0001] This invention relates to the field of electrical discharge machining (EDM) technology, and in particular to an adaptive powder mixing-assisted EDM system and method. Background Technology

[0002] Traditional electrical discharge machining (EDM) suffers from localized high temperatures at the discharge point, which can easily cause thermal damage, microcracks, and surface recasting layers, resulting in poor surface roughness and making it difficult to meet the requirements of high-precision mirror finishing. An existing powder-assisted machining method improves surface roughness by adding conductive micro-powders to the working fluid and altering the spark discharge state. However, existing powder-assisted machining devices often use fixed process parameters and fixed powder mixing ratios, failing to adapt to actual working conditions, making it difficult to balance machining accuracy and efficiency. Furthermore, the powder mixing devices often employ a single stirring structure, leading to powder agglomeration and sedimentation, resulting in poor powder uniformity and affecting discharge stability and machining quality. Moreover, the low level of automation and mismatch between mixing and processing rhythms create a contradiction between continuous production and maintaining powder uniformity.

[0003] Therefore, in order to improve the overall process level of electrical discharge machining, there is an urgent need for a technical solution that can adaptively adjust powder mixing to maintain the uniformity of powder mixing in continuous production. Summary of the Invention

[0004] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides an adaptive powder mixing assisted EDM system and method. By adaptive liquid and powder replenishment and adaptive dual-drive stirring in synergy, the uniformity effect is enhanced while the non-uniformity window period is effectively shortened, so as to solve the contradiction between continuous processing production and maintaining powder mixing uniformity.

[0005] Technical Solution: To achieve the above objectives, the present invention provides an adaptive powder-mixing assisted electrical discharge machining (EDM) system, comprising a machining subsystem, a powder mixing subsystem, and a filtration subsystem. The machining subsystem performs EDM and precisely sprays a composite machining fluid into the machining gap between the electrode and the workpiece to achieve cooling, chip removal, and assisted discharge. The powder mixing subsystem selects mixed powders of different particle sizes according to working conditions and mixes them uniformly with the clarified machining fluid according to a preset ratio to form the composite machining fluid. The filtration subsystem separates the mixed powder and clarified working fluid from the waste liquid and recycles them to the powder mixing subsystem for reuse. The powder mixing subsystem includes a dual-drive stirring mechanism. The dual-drive stirring mechanism generates centrifugal force through mechanical stirring and forms a swirling stirring effect through the centrifugal force drive and the pump drive. The swirling stirring and the mechanical stirring work together to form a spatial circulating stirring flow along the axial direction of the mechanical stirring shaft, so that the supplied composite machining fluid can maintain stable uniformity during continuous machining by the machining subsystem.

[0006] Furthermore, the dual-drive stirring mechanism includes a mechanical stirring structure connected to a drive motor. The mechanical stirring structure is located at the bottom of the stirring chamber and rotates around the vertical axis of the stirring chamber. The mechanical stirring structure has an integrated closed flow channel inside. The liquid inlet of the closed flow channel is located in the middle of the stirring chamber, and a filter structure is provided at the liquid inlet. Multiple liquid outlets of the closed flow channel are respectively connected to a nozzle. The multiple nozzles are distributed along the circumference on the mechanical stirring structure so that their spray direction is in the same direction as the radial direction of the rotation axis of the mechanical stirring structure.

[0007] Furthermore, a liquid pump is provided at the liquid inlet end of the closed flow channel.

[0008] Furthermore, a concentration sensor array is arranged vertically inside the stirring chamber. The concentration sensor array, the drive motor, and the pump are all connected to the first control module. When the local concentration peak in the stirring chamber exceeds a pre-threshold, the mechanical stirring speed and the jet intensity are automatically adjusted to shorten the concentration unevenness window period.

[0009] Furthermore, the nozzle integrates a one-way valve. When the rotational stirring speed of the mechanical stirring structure exceeds a preset threshold, the one-way valve can open under the action of centrifugal force; or when the mechanical stirring structure rotates at any speed, the one-way valve can open under the radial jet push from the inside to the outside.

[0010] Furthermore, the nozzle includes a rotor, the rotation axis of which is radially arranged along the rotation axis of the mechanical stirring structure; the rotor has a guide hole along its own axial direction, the inner port of the guide hole is connected to the liquid outlet of the closed flow channel, the outer port of the guide hole forms a high-flow nozzle, and a plurality of low-flow nozzles are evenly distributed on the outer circumference of the rotor, the guiding direction of the nozzles is arranged radially along the rotor.

[0011] Furthermore, the powder mixing subsystem includes at least three mixing chambers adapted to different degrees of finishing, semi-finishing, and roughing. The liquid replenishment port of each mixing chamber is connected to the clear liquid tank via a liquid replenishment pump. Each mixing chamber is respectively provided with a powder mixing feeding bin, and each powder mixing feeding bin stores the mixed powder with different particle sizes. Each mixing chamber is provided with a liquid level sensor array and a concentration sensor array. The liquid level sensor array, the concentration sensor array, each liquid replenishment pump, and each powder mixing feeding bin are all connected to the second control module to replenish liquid when the liquid level in the mixing chamber is lower than a preset value, and to replenish powder when the local concentration in the chamber is low due to liquid replenishment.

[0012] Furthermore, the filtration subsystem includes a first filtration cycle and a second filtration cycle. The first filtration cycle is used to separate the fine mixed powder from the floating liquid generated in the preliminary vibration filtration stage by centrifugation to obtain a recyclable clear processing fluid, and the separated mixed powder is returned to the preliminary vibration filtration stage to form a cycle. The second filtration cycle is used to re-filter the bottom slag generated in the preliminary vibration filtration stage to obtain a recyclable mixed powder containing slag, and the filtrate is returned to the preliminary vibration filtration stage to form a cycle.

[0013] Furthermore, an adaptive powder mixing-assisted electrical discharge machining method includes the following steps:

[0014] S1. The powder mixing subsystem selects the appropriate stirring chamber and connects it to the liquid distribution structure of the processing subsystem according to the processing conditions to provide a composite processing liquid mixed with powder of the required particle size.

[0015] S2. The processing subsystem performs grinding and sprays the composite processing fluid into the processing gap between the electrode and the workpiece to achieve cooling, chip removal, and auxiliary discharge. During the process, the second control module controls dynamic fluid replenishment and dynamic powder replenishment based on real-time monitored changes in liquid level and concentration at replenishment points. The first control module controls the dual-drive stirring mechanism to perform adaptive cooperative stirring based on real-time monitored changes in powder concentration at replenishment points to minimize the window period of uneven concentration within the stirring chamber.

[0016] S3. The filtration subsystem performs multi-stage filtration based on dual circulation on the waste liquid discharged from the grinding process to separate the clear processing liquid and mixed powder in the waste liquid, which are then recycled by the powder mixing subsystem.

[0017] Beneficial Effects: This invention provides an adaptive powder mixing-assisted EDM system and method. By setting up a powder mixing subsystem with multiple independent stirring chambers, it achieves the process requirement of using different powder particle sizes to assist processing according to the processing conditions. By setting up a filtration subsystem, it achieves efficient separation of aluminum powder, processing iron filings, and clear liquid, and enables the recycling of aluminum powder, reducing waste liquid discharge, lowering production costs, and saving energy and protecting the environment. By setting up a dual-drive stirring mechanism, it achieves uniform stirring and anti-sedimentation of the composite processing liquid, maintaining its continuous uniformity. By deploying liquid level sensors and concentration sensors, it achieves automatic liquid and powder replenishment control, ensuring a continuous supply and stable concentration of the composite processing liquid. Through a dynamic adjustment strategy based on concentration monitoring and control of the stirring mode, it quickly responds to localized concentration unevenness caused by liquid and powder replenishment, and minimizes the concentration unevenness window period, resolving the contradiction between continuous production and maintaining powder mixing uniformity in actual production. Attached Figure Description

[0018] Figure 1This is a schematic diagram of the overall structure of an adaptive powder mixing-assisted electrical discharge machining system according to an embodiment of the present invention.

[0019] Figure 2 This is a cross-sectional schematic diagram of a spindle machining head according to an embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of an electrode grinding head according to an embodiment of the present invention.

[0021] Figure 4 This is a cross-sectional schematic diagram of a vortex stirrer according to an embodiment of the present invention.

[0022] Figure 5 This is a schematic diagram of the rotor according to one embodiment of the present invention. Detailed Implementation

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] As attached Figure 1-5 An adaptive powder mixing-assisted electrical discharge machining (EDM) system includes a machining subsystem 1, a powder mixing subsystem 2, and a filtration subsystem 3. This embodiment uses EDM grinding as an example. The machining system 1 includes a machine frame worktable, on which a spindle machining head 11 is mounted for performing EDM grinding. Figure 2 As shown, the spindle machining head 11 includes a machining spindle 111, which axially passes through and is rotatably mounted within a housing 112. The housing 112 is used to connect a multi-degree-of-freedom moving platform to meet flexible machining requirements. An electrode grinding head 113 is fixedly mounted on the lower end of the machining spindle 111. An insulating gasket 114 is placed between the electrode grinding head 113 and the machining spindle 111 to prevent machining current from being conducted to the machine frame through the machining spindle, thus ensuring machining safety and discharge stability.

[0025] like Figure 3 As shown, the electrode grinding head 113 includes a mounting flange 113a and a working section 113b. An axial liquid distribution channel is provided inside the electrode grinding head 113. The liquid inlet end of the liquid distribution channel 113c is connected to the composite processing liquid supply pipeline of the powder mixing subsystem 2. The liquid distribution channel 113c is provided with a plurality of liquid distribution holes 113d on the outer circumferential surface of the working section 113b. In this embodiment, the liquid distribution holes 113d are evenly distributed in three rows with six holes in each row.

[0026] With the combined action of the rotation of the machining spindle 111 and the spraying of the composite machining fluid, the composite machining fluid can be accurately and evenly sprayed into the machining gap between the electrode grinding head and the workpiece, realizing multiple functions such as cooling of the workpiece and grinding head, chip removal, and auxiliary electrode discharge.

[0027] The processing fluid supply pipeline includes an internal pipe section integrated axially within the processing spindle 111, and an external pipe section connecting the processing subsystem 1 and the powder mixing subsystem 2. A suction pump is installed on the external pipe section for actively drawing out the uniformly mixed composite processing fluid. An O-ring is provided at the connection between the internal pipe section and the fluid distribution channel 113c to enhance the sealing at the connection between the electrode grinding head and the processing spindle, preventing processing fluid leakage from the connection.

[0028] In this embodiment, the powder mixing subsystem 2 includes stirring chambers 6 corresponding to three different aluminum powder particle sizes, respectively adapted to finishing, semi-finishing, and roughing conditions. The external pipe sections are connected to the three stirring chambers 6 via branch pipes, each branch pipe being equipped with an electric valve to open the corresponding electric valve according to the working condition, thereby enabling selection of the composite processing fluid containing different mixed powder particle sizes. Accordingly, in this embodiment, the process parameters of the processing subsystem 1 corresponding to the finishing, semi-finishing, and roughing conditions are as follows: Finishing: peak current 6A, pulse width 3µs, grinding speed 800r / min.

[0029] Semi-finishing: peak current 8A, pulse width 6µs, grinding speed 600r / min.

[0030] Rough machining: peak current 10A, pulse width 9µs, grinding speed 8400r / min.

[0031] Each of the stirring chambers 6 is respectively provided with a powder mixing feeding bin 10, and each powder mixing feeding bin 10 stores the mixed powder of the corresponding particle size; such as Figure 1 As shown, the corresponding aluminum powder particle sizes from left to right are 15μm, 30μm, and 45μm, respectively.

[0032] The outlet of the waste liquid collection tank of the machine frame workbench is connected to the filtration subsystem 3 through a drain pipe. The filtration subsystem 3 is used to separate the mixed powder and the clear working liquid in the waste liquid and recycle them to the powder mixing subsystem for reuse.

[0033] The filtration subsystem 3 includes an initial vibrating filter 31, a secondary cyclone filter 32, and a powder mixing and recovery unit 33. The inlet of the initial vibrating filter 31 is connected to the outlet of the waste liquid collection tank of the machine frame workbench via a pipe. The upper liquid phase outlet of the initial vibrating filter 31 is connected to the secondary cyclone filter 32. The secondary cyclone filter 32 uses centrifugal force to separate fine aluminum powder particles from the clear liquid. The bottom slag return port of the secondary cyclone filter 32 is connected to the primary vibrating filter 31 to form the first filtration cycle. The fine particles that have been centrifuged and aggregated will more easily settle to the bottom slag area when they return to the vibrating filter, so that they can enter the second filtration cycle for powder mixing and recovery.

[0034] The upper clear liquid of the secondary cyclone filter 32 is connected to the clear liquid tank 9. The clear liquid tank 9 is connected to the replenishment ports of multiple stirring chambers 6 through replenishment pipelines. Each replenishment pipeline is equipped with a corresponding replenishment pump 91. This enables the recycling and reuse of the clear liquid from the feed solution.

[0035] The bottom slag outlet of the initial vibration filter 31 is connected to the powder mixing and recovery device 33, and the filtrate outlet of the powder mixing and recovery device 33 is connected to the processing fluid inlet of the initial vibration filter 31 to form a second filtration cycle, so as to return the supernatant of the processing fluid entrained in the bottom slag and enter the first filtration cycle for the recovery of the supernatant.

[0036] Through the above-mentioned dual-cycle multi-stage filtration system, the supernatant, mixed powder and processing iron filings can be separated to the maximum extent, realizing the effective recycling of resources.

[0037] like Figure 1 As shown, the powder mixing subsystem 1 includes a dual-drive stirring mechanism 4. This mechanism generates centrifugal force through mechanical stirring, and the centrifugal force, in conjunction with the pump's liquid drive, forms a swirling stirring flow. This swirling stirring, in conjunction with the mechanical stirring, creates a spatial circulating stirring flow along the axial direction of the mechanical stirring axis. Since the vortex of the formed swirling flow is generated by both the wall shearing of the mechanical stirring and the fluid volume force of the jet impact, a radial high-pressure jet is superimposed on the tangential stirring force. This is a coupling of active jet and passive rotation. The radial jet breaks the axisymmetric laminar flow tendency of pure rotation, generating a strong radial velocity component and axial entrainment, producing a vortex-like flow. The radial jet also continuously penetrates the inertial layer of the rotating fluid, forcing the exchange of internal and external fluids. The resulting strong axial circulating fluid continuously pushes the outer particles upwards and inwards, counteracting the radial particle segregation caused by centrifugal force. This effectively disrupts the radial particle sorting produced by pure mechanical stirring. The entrainment effect of the radial jet drives the bottom fluid upwards, forming an overall upward, inward, downward, and reflux cycle, ensuring uniform particle distribution in three-dimensional space. This not only achieves better mixing and stirring effects but also effectively prevents aluminum powder sedimentation. This ensures that the supplied composite processing fluid maintains stable uniformity during continuous processing by the processing subsystem 1.

[0038] In this embodiment, the dual-drive stirring mechanism 4 includes a mechanical stirring structure 5, which is connected to a drive motor 41. The mechanical stirring structure 5 is arranged at the bottom of the stirring chamber 6 and rotates around the vertical axis of the stirring chamber 6. The mechanical stirring structure 5 has an integrated closed flow channel inside, and the liquid inlet 51 of the closed flow channel is located in the middle of the stirring chamber 6. A filter structure is provided at the liquid inlet 51. Multiple liquid outlets of the closed flow channel are respectively connected to a nozzle 7. Multiple nozzles 7 are distributed and installed on the mechanical stirring structure 5 in a circumferential direction so that their spraying direction is in the same direction as the radial direction of the rotation axis of the mechanical stirring structure 5. Based on the above structure, when the mechanical stirring structure 5 is driven to rotate by the drive motor 41, the liquid in the closed flow channel is forced to move outward by centrifugal force, thereby forming high pressure at the nozzle and low pressure at the inlet 51. The pressure difference generated by centrifugation creates a forced flow from the inlet 51 towards the nozzle 7, automatically drawing the liquid from the middle of the stirring chamber 6 into the internal closed flow channel, and then ejecting it from the bottom of the stirring chamber 6 to form a radial jet. Combined with the rotation of the mechanical stirring structure 5 itself, this creates a complex vortex at the bottom of the stirring chamber 6. The filter structure at the inlet 51 prevents aluminum powder from entering the closed flow channel and causing blockage.

[0039] Preferably, the inlet 51 is located in the descending fluid near the axis of rotation, and the opening is downward or horizontal. This ensures that the portion of the processing fluid used to form the jet conforms to the overall circulating and stirred flow trend, with only a small portion of the fluid flowing out from the inside of the stirring structure. This results in a concentration deviation only in the inner descending fluid, while the sampling point for the composite processing fluid in the processing subsystem 1 is typically located in the outer fluid layer. This ensures the stable uniformity of the aluminum powder in the supplied composite fluid. Furthermore, the flow direction is consistent with the suction direction, which helps improve suction efficiency and minimizes pressure drop. The descending fluid can carry away powder from the filter screen surface, preventing clogging.

[0040] Preferably, the liquid inlet end of the closed flow channel is equipped with a liquid pump 42. Based on the passive jet generated by centrifugal force, the strength of the jet can be controlled by the active pumping of the liquid pump 42, so that the proportion of mechanical stirring and jet stirring can be independently adjusted during the actual stirring process.

[0041] Preferably, the nozzle 7 integrates a one-way valve 8, which can be opened under centrifugal force; or when the mechanical stirring structure 5 rotates at any speed, the one-way valve 8 can be opened under the radial jet push from the inside to the outside.

[0042] like Figure 4As shown, the one-way valve 8 consists of a valve ball that can move along the jet direction and a return spring; when the rotational stirring speed of the mechanical stirring structure 5 exceeds a preset threshold, the superposition of the centrifugal force on the valve ball and the thrust of the fluid alignment exceeds the clamping force of the return spring, the valve ball is pushed open, causing the nozzle to open and forming a radial jet.

[0043] like Figure 5 As shown, the nozzle 7 includes a rotor 71, the rotation axis of which is radially arranged along the rotation axis of the mechanical stirring structure 5; the rotor 71 has a guide hole 72 along its own axial direction, the inner port of the guide hole 72 is connected to the liquid outlet of the closed flow channel, and the outer port of the guide hole 72 forms a high-flow-rate nozzle 721; a plurality of low-flow-rate spray holes 722 are evenly distributed on the outer circumferential surface of the rotor 71, and the guiding direction of the spray holes 722 is arranged radially along the rotor 71. This allows the liquid drawn into the closed flow channel to be mainly ejected as a radial jet, while a small portion will form a circumferential jet array perpendicular to the jet direction near the nozzle, thereby creating turbulence in a small area and further breaking up the agglomerated powder.

[0044] Furthermore, each of the stirring chambers 6 is equipped with a liquid level sensor array and a concentration sensor array. The liquid level sensor array, the concentration sensor array, each of the replenishing pumps 91, and each of the powder mixing and feeding bins 10 are all connected to the second control module to replenish liquid when the liquid level in the stirring chamber 6 is lower than a preset value, and to replenish powder when the concentration in the chamber is locally low due to replenishment. As the processing subsystem continues to process, the composite processing liquid in the stirring chamber is continuously reduced. When the liquid level drops to a certain height, for example, to a certain height distance above the liquid inlet 51, it may affect the swirling stirring effect. At this time, an automatic replenishment process is triggered, and the corresponding replenishing pump 91 is turned on to replenish a certain amount of processing liquid. The replenishment of processing liquid will inevitably create a local low concentration area at the replenishment point. This area is detected by the concentration sensor array and triggers the automatic powder replenishment process. According to the replenishment amount, the corresponding quantitative mixed powder is automatically replenished to ensure that the total amount of processing liquid and the total amount of aluminum powder in the stirring chamber 6 can meet the preset concentration requirements after being stirred evenly.

[0045] To quickly eliminate localized non-uniformity caused by replenishment of liquid and powder, a dynamic adjustment strategy of mechanical stirring and swirling stirring is implemented. When the concentration of the composite processing liquid in the stirring chamber 6 is within a uniform range, both the drive motor 41 and the pump 42 operate at a preset power, maintaining a fixed proportional relationship between the contributions of mechanical stirring and swirling stirring. When localized fluctuations occur in the internal concentration due to replenishment of liquid or powder, this proportion is adjusted to temporarily enhance a particular effect, achieving rapid homogenization.

[0046] Specifically, the concentration sensing array, drive motor 41, and pump 42 are all connected to the first control module. This module automatically triggers coordinated adjustment of the mechanical stirring speed and jet intensity when the local concentration peak in the stirring chamber 6 exceeds a pre-threshold, thereby shortening the concentration unevenness window period. For example, during powder replenishment, the injection ratio is temporarily increased to quickly disperse the replenished powder and transport it outwards, preventing deposition or floating in locally overly concentrated areas.

[0047] Preferably, the powder replenishment points are multi-point and evenly distributed within the annular region of the nozzle 7 jet. The radial jet and circumferential jet array ejected by the nozzle 7 quickly disperse the added powder, which is then pushed outward and rises along the wall, mixing into the rising flow of the circulating stirring flow.

[0048] Preferably, the replenishment point is located in the bottom center area of ​​the stirring chamber 6, so that the replenished processing fluid can directly enter the jet zone and quickly complete the initial mixing with the newly added powder.

[0049] When replenishing powder, the spray ratio is temporarily increased while the stirring speed is simultaneously decreased. The strong turbulence and shear force generated by the high-speed jet rapidly disperse the concentrated clumps near the feeding point and transport them outwards. After a period of time, the stirring speed is temporarily increased while the spray ratio is simultaneously decreased. The overall circulation generated by stirring evenly distributes the initially dispersed aluminum powder throughout the cavity, eliminating any residual macroscopic concentration gradient. Once the monitored concentration distribution falls within the preset range, the optimal anti-settling ratio is restored.

[0050] Preferably, the optimal ratio (i.e., conventional value) for preventing settling is 55%-65% mechanical stirring power and 35%-45% swirl jet power. When adding powder, the swirl jet pressure is automatically increased to 1.5-2 times the conventional value, and the stirring speed is reduced to 55%-75% of the conventional value. After continuous high-jet dispersion is completed, the stirring speed is automatically increased to 1.2-1.3 times the conventional value, while the radial jet pressure is reduced to 35%-55% of the conventional value.

[0051] Furthermore, the liquid replenishment action can directly trigger the dynamic adjustment of the stirring, thereby creating a strong turbulent preparatory state in the stirring chamber before the powder replenishment, so that the replenished powder is dispersed instantly, significantly shortening the unevenness window period.

[0052] An adaptive powder mixing-assisted electrical discharge machining method, characterized by comprising the following steps:

[0053] S1. The central controller sets the machining condition to finish, semi-finish, or roughing based on the material of the workpiece (such as mold steel, cemented carbide, etc.), machining accuracy requirements, and machining allowance. Then, the central controller sets the corresponding machining current, the grinding speed of the spindle head, and the on / off state of the mixing chamber 6 of the machining fluid with the corresponding powder particle size to provide a composite machining fluid containing powder of the required particle size.

[0054] S2. The machining subsystem 1 performs grinding. The composite machining fluid is delivered to the machining fluid inlet of the spindle machining head through the machining fluid supply pipeline. It is then precisely sprayed into the machining gap between the electrode and the workpiece through the fluid distribution hole 113d on the surface of the electrode grinding head 113 to achieve cooling, chip removal and auxiliary discharge.

[0055] During the process, the second control module controls dynamic liquid replenishment and dynamic powder replenishment based on real-time monitored changes in liquid level and concentration at replenishment points; the first control module controls the dual-drive stirring mechanism 4 to perform adaptive cooperative stirring based on real-time monitored changes in powder concentration at replenishment points, so as to minimize the window period of uneven concentration in the stirring chamber 6.

[0056] S3. The filtration subsystem 3 performs multi-stage filtration based on dual circulation on the waste liquid discharged from the grinding process to separate the clear processing liquid and mixed powder in the waste liquid, which are then recycled by the powder mixing subsystem 2.

[0057] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the above principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An adaptive powder mixing-assisted electrical discharge machining system, characterized in that, include: The machining subsystem (1) is used to perform electrical discharge machining and to precisely spray the composite machining fluid into the machining gap between the electrode and the workpiece to achieve cooling, chip removal and auxiliary discharge. The powder mixing subsystem (2) is used to select mixed powders of different particle sizes according to the working conditions, and mix them evenly with the clear liquid of the processing fluid according to the preset ratio to form the composite processing fluid; The filtration subsystem (3) is used to separate the mixed powder and the clear working liquid in the waste liquid and recycle them to the powder mixing subsystem for reuse. The powder mixing subsystem (1) includes a dual-drive stirring mechanism (4). The dual-drive stirring mechanism (4) generates centrifugal force through mechanical stirring and forms a swirling stirring in coordination with the pump liquid drive through centrifugal force. The swirling stirring and the mechanical stirring work together to form a spatial circulating stirring flow along the axis of the mechanical stirring shaft, so that the composite processing liquid supplied can maintain stable uniformity when the processing subsystem (1) is continuously processing.

2. The adaptive powder mixing-assisted EDM system according to claim 1, characterized in that: The dual-drive stirring mechanism (4) includes a mechanical stirring structure (5), which is connected to a drive motor (41). The mechanical stirring structure (5) is arranged at the bottom of the stirring chamber (6) and rotates around the vertical axis of the stirring chamber (6). The mechanical stirring structure (5) has an integrated closed flow channel inside. The liquid inlet (51) of the closed flow channel is located in the middle of the stirring chamber (6), and a filter structure is provided at the liquid inlet (51). The multiple liquid outlets of the closed flow channel are respectively connected to a nozzle (7). The multiple nozzles (7) are distributed along the circumferential direction on the mechanical stirring structure (5) so that their liquid spraying direction is in the same direction as the radial direction of the rotating shaft of the mechanical stirring structure (5).

3. The adaptive powder mixing-assisted EDM system according to claim 2, characterized in that: The liquid inlet end of the closed flow channel is equipped with a liquid pump (42).

4. The adaptive powder mixing-assisted EDM system according to claim 3, characterized in that: A concentration sensor array is arranged vertically inside the stirring chamber (6). The concentration sensor array, the drive motor (41), and the pump (42) are all connected to the first control module. When the local concentration peak in the stirring chamber (6) exceeds the pre-threshold, the mechanical stirring speed and the jet intensity are automatically triggered to adjust in coordination, so as to shorten the concentration unevenness window period.

5. An adaptive powder mixing-assisted EDM system according to claim 2 or 3, characterized in that: The nozzle (7) integrates a one-way valve (8). When the rotation speed of the mechanical stirring structure (5) exceeds a preset threshold, the one-way valve (8) can be opened under the action of centrifugal force; or when the mechanical stirring structure (5) rotates at any speed, the one-way valve (8) can be opened under the radial jet push from the inside to the outside.

6. An adaptive powder mixing-assisted EDM system according to claim 2 or 3, characterized in that: The nozzle (7) includes a rotor (71), the rotation axis of which is radially arranged along the rotation axis of the mechanical stirring structure (5); the rotor (71) has a guide hole (72) along its own axial direction, the inner port of the guide hole (72) is connected to the liquid outlet of the closed flow channel, the outer port of the guide hole (72) forms a high flow nozzle (721), and a number of low flow nozzles (722) are evenly distributed on the outer circular surface of the rotor (71), and the guiding direction of the nozzles (722) is radially arranged along the rotor (71).

7. The adaptive powder mixing-assisted EDM system according to claim 1, characterized in that: The powder mixing subsystem (2) includes at least three mixing chambers (6) adapted to different degrees of finishing, semi-finishing and roughing. The liquid replenishment port of each mixing chamber (6) is connected to the clear liquid tank (9) through a liquid replenishment pump (91). Each mixing chamber (6) is respectively provided with a powder mixing feeding bin (10), and each powder mixing feeding bin (10) stores the mixed powder with different particle sizes. Each of the stirring chambers (6) is equipped with a liquid level sensor array and a concentration sensor array. The liquid level sensor array, the concentration sensor array, each of the replenishing pumps (91) and each of the mixing powder feeding bins (10) are all connected to the second control module to replenish liquid when the liquid level in the stirring chamber (6) is lower than the preset value, and to replenish powder when the local concentration in the chamber is low due to replenishing liquid.

8. The adaptive powder mixing-assisted EDM system according to claim 1, characterized in that: The filtration subsystem (3) includes a first filtration cycle and a second filtration cycle. The first filtration cycle is used to separate the fine mixed powder from the floating liquid generated in the preliminary vibration filtration stage by centrifugation to obtain a recyclable clear processing liquid, and to return the separated mixed powder to the preliminary vibration filtration stage to form a cycle. The second filtration cycle is used to re-filter the bottom slag generated in the preliminary vibration filtration stage to obtain recyclable slag-containing mixed powder, and to return the filtrate to the preliminary vibration filtration stage to form a cycle.

9. An adaptive powder-mixing assisted electrical discharge grinding method based on the system described in any one of claims 1-8, characterized in that, Includes the following steps: S1. The powder mixing subsystem (2) selects the appropriate stirring chamber (6) according to the processing conditions and connects it with the liquid distribution structure of the processing subsystem (1) to provide a composite processing liquid mixed with powder of the required particle size. S2. The processing subsystem (1) performs grinding and sprays the composite processing fluid into the processing gap between the electrode and the workpiece to achieve cooling, chip removal and auxiliary discharge. During the process, the second control module controls the dynamic replenishment of liquid and the dynamic replenishment of powder based on the real-time monitored changes in liquid level and concentration at the replenishment point; the first control module controls the dual-drive stirring mechanism (4) to perform adaptive cooperative stirring based on the real-time monitored changes in concentration at the replenishment point, so as to maximize the shortening of the uneven concentration window period in the stirring chamber (6); S3. The filtration subsystem (3) performs multi-stage filtration based on dual circulation on the waste liquid discharged from the grinding process to separate the clear liquid of the processing liquid and the mixed powder in the waste liquid, which are then recycled by the powder mixing subsystem (2).

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