Electrochemical machining device and method for electrochemical machining of a vortex disc by means of a bipolar power supply

Abstract

This invention relates to an electrolytic machining apparatus and method for bipolar power supply electrolytic machining of scroll disks. The electrolytic machining apparatus includes an electrolytic cell, a tool electrode and a workpiece electrode disposed within the electrolytic cell, a first circuit system, a second circuit system, and an eccentric constant-speed / variable-speed rotating mechanism. The first circuit system includes an adjustable DC power supply E1, an insulated-gate bipolar transistor (IGBT) Q1, and an IGBT Q2. The second circuit system includes an adjustable DC power supply E2, an IGBT Q3, and an IGBT Q4. The eccentric constant-speed / variable-speed rotating mechanism is used to drive the tool electrode-moving scroll disk or the tool electrode-stationary scroll disk to perform conjugate meshing motion. The electrolytic machining apparatus of this invention can solve the technical problems of severe tool wear, uneven cutting temperature distribution, and stress deformation at thin-walled sections in traditional precision machining of the moving and stationary scroll disks of scroll compressors, which lead to difficulties in controlling the shape and dimensional accuracy, as well as the difficulty in ensuring the consistency of radial clearance during the "meshing" operation of the moving and stationary scroll disks.

Description

Technical Field

[0001] This invention relates to the field of special processing technology, specifically to an electrolytic processing apparatus and method for bipolar power supply electrolytic processing of a scroll plate. Background Technology

[0002] The scroll disk is a typical precision part with a complex profile, narrow tooth grooves, and a large tooth height-to-thickness ratio. Furthermore, the material of the scroll disk is difficult to machine, making its processing extremely challenging. The specific difficulties in its manufacturing are as follows:

[0003] (1) The spiral disk profile is an involute, and its wall surface needs to be machined using multi-axis CNC machine tools and complex-shaped cutting tools.

[0004] (2) The scroll disk material is a difficult-to-cut material (such as silicon aluminum alloy 4032, which contains hard Si particles precipitated by eutectic). The tool is prone to wear during machining, and superhard tools such as PCD or coated tools are required, which results in high tool material and manufacturing costs.

[0005] (3) The scroll disk has a thin-walled structure, which makes it easy to produce problems such as uneven cutting temperature distribution and excessive stress deformation during precision machining (such as high-speed precision milling machining centers);

[0006] (4) The basic requirement of the vortex disk profile meshing theory is that the profiles of the moving and stationary vortex disks remain conjugate to each other.

[0007] Therefore, in order to minimize tangential leakage and interference ( Figure 1 This places high demands on the machining accuracy of the scroll plate profile. Typically, the radial gap between the walls of the moving and stationary scroll plates after assembly must be within 40μm, and for each scroll plate, the contour accuracy of its wall profile must be controlled within 10μm to 15μm, requiring the use of expensive ultra-precision machining tools.

[0008] Therefore, the aforementioned manufacturing difficulties of the scroll plate limit the further improvement of the performance of the scroll compressor, and also keep its manufacturing difficulty and cost high, further increasing the cost of fuel cell stacks and systems, becoming one of the key technical bottlenecks hindering the large-scale mass production of hydrogen fuel cell vehicles. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide an electrolytic machining device for bipolar power supply electrolytic machining of scroll disks. The electrolytic machining device can solve the technical problems of severe tool wear, uneven cutting temperature distribution and stress deformation at thin-walled sections of the moving and stationary scroll disks of scroll compressors in traditional precision machining, which lead to difficulties in controlling the shape and size accuracy, as well as the difficulty in ensuring the consistency of radial clearance when the moving and stationary scrolls are "meshing" during operation.

[0010] A second objective of the present invention is to provide an electrochemical machining method for the above-described electrochemical machining apparatus.

[0011] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0012] An electrolytic machining apparatus for a bipolar power supply electrolytic machining scroll wheel includes an electrolytic cell, a tool electrode and a workpiece electrode disposed within the electrolytic cell, a circuit system, and an eccentric constant-speed / variable-speed rotation mechanism for driving the tool electrode to rotate around the Z-axis.

[0013] The electrolytic cell is filled with a neutral electrolyte; the stationary vortex disk and the moving vortex disk to be processed constitute the workpiece electrode and the tool electrode, respectively; the workpiece electrode is divided into workpiece electrode-stationary vortex disk and workpiece electrode-moving vortex disk; the tool electrode is divided into tool electrode-moving vortex disk and tool electrode-stationary vortex disk; the stationary vortex disk and the moving vortex disk are in a conjugate meshing state; wherein, the suction port and discharge port of the stationary vortex disk and the moving vortex disk in the conjugate meshing state are both connected to the neutral electrolyte in the electrolytic cell;

[0014] The circuit system is used to alternately apply positive and negative pulse voltages to the moving and stationary scroll disks, and includes a first circuit system and a second circuit system, wherein...

[0015] The first circuit system includes an adjustable DC power supply E1, an insulated gate bipolar transistor Q1, and an insulated gate bipolar transistor Q2. The positive terminal of the adjustable DC power supply E1 is connected in sequence to the insulated gate bipolar transistor Q1 and the workpiece electrode-static vortex disk in the electrolytic cell. The negative terminal of the adjustable DC power supply E1 is connected to the tool electrode-moving vortex disk in the electrolytic cell.

[0016] The second circuit system includes an adjustable DC power supply E2, an insulated-gate bipolar transistor (IGBT) Q3, and an IGBT Q4. The positive terminal of the adjustable DC power supply E2 is connected in sequence to the IGBT Q3 and the workpiece electrode (moving scroll plate) in the electrolytic cell. The negative terminal of the adjustable DC power supply E2 is connected to the tool electrode (stationary scroll plate) in the electrolytic cell. A current-limiting resistor R is added to the negative terminal line of the IGBT Q4 and the adjustable DC power supply E2.

[0017] The eccentric constant speed / variable speed rotation mechanism is used to drive the tool electrode-moving scroll or the tool electrode-stationary scroll to perform conjugate meshing motion, causing the neutral electrolyte in the electrolytic cell to be drawn from the suction port into the machining gap between the stationary scroll and the moving scroll, move along the machining gap, and be discharged from the discharge port.

[0018] Preferably, it further includes a vertical adjustment mechanism for adjusting the gap between the tool electrode and the workpiece electrode.

[0019] Preferably, the vertical adjustment mechanism is a Z-axis servo motor, which is used to drive the tool electrode to make vertical movements.

[0020] An electrolytic machining method for a bipolar power supply electrolytic machining scroll plate, employing the aforementioned electrolytic machining apparatus; during machining, the circuit system alternately applies positive and negative pulse voltages to the moving and stationary scroll plates, while simultaneously, an eccentric constant / variable speed rotation mechanism drives the tool electrode to rotate eccentrically, causing the moving and stationary scroll plates to engage in conjugate meshing motion, resulting in the neutral electrolyte in the electrolytic cell being drawn into the machining gap between the workpiece electrode and the tool electrode, and moving along the extension direction of the machining gap; under the alternating application of positive and negative pulse voltages, the neutral electrolyte electrochemically dissolves both sides of the machining gap; when the neutral electrolyte reaches the discharge port, it forms a high-speed jet with the compressed neutral electrolyte moving within the machining gap and is discharged, carrying away the machining product.

[0021] Preferably, during the positive pulse voltage tp, insulated-gate bipolar transistors Q1 and Q4 are turned on under the control of drive signals G1 and G4, respectively; insulated-gate bipolar transistors Q2 and Q3 are turned off under the control of drive signals G2 and G3, respectively; at this time, the workpiece electrode-moving scroll is subjected to a high level from the adjustable DC power supply E1, while the tool electrode-stationary scroll is grounded; an electrolytic machining circuit is formed between the workpiece electrode-moving scroll and the tool electrode-stationary scroll; under the action of the positive pulse voltage U1, the electrolytic machining circuit generates a machining current I1, and Al on the surface of the workpiece electrode-moving scroll undergoes a dissolution reaction; while the tool electrode-stationary scroll undergoes a hydrogen evolution reaction.

[0022] Preferably, during the negative pulse voltage tn, insulated-gate bipolar transistors Q1 and Q4 are turned off under the control of drive signals G1 and G4, respectively, while insulated-gate bipolar transistors Q2 and Q3 are turned on under the control of drive signals G2 and G3, respectively. At this time, the workpiece electrode-moving scroll is grounded, and the tool electrode-stationary scroll is subjected to a high level from the adjustable DC power supply E2. An electrolytic machining circuit is formed between the workpiece electrode-moving scroll and the tool electrode-stationary scroll. Under the action of the negative pulse machining voltage U2, the electrolytic machining circuit generates a machining current I2, and the Al on the surface of the tool electrode-stationary scroll undergoes a dissolution reaction; while the workpiece electrode-moving scroll undergoes a hydrogen evolution reaction.

[0023] Preferably, the dissolution reaction is as follows:

[0024] Al→Al 3+ +3e - (1)

[0025] Al 3+ +3OH - →Al(OH)3↓ (2)

[0026] The hydrogen evolution reaction is as follows:

[0027] 2H2O+2e - →H₂↑+2OH⁻ - (3)

[0028] Preferably, a dead time t is set between the positive pulse voltage period and the negative pulse voltage period. d .

[0029] Preferably, the FPGA main control chip of the synchronous adjustable high-power bipolar pulse power supply in the adjustable DC power supply E1 and the adjustable DC power supply E2 sends an ultra-short pulse signal to the gate of the insulated gate bipolar transistors Q1, Q2, Q3, and Q4. After being isolated and driven by the amplifier circuit, the ultra-short pulse signal controls the insulated gate bipolar transistors Q1, Q2, Q3, and Q4 to chop the DC voltage output by the adjustable DC power supply E1 and E2, and output adjustable positive and negative pulse voltages.

[0030] Preferably, a short-circuit protection circuit is added to the electrolytic machining apparatus. The short-circuit protection circuit uses a voltage follower, a non-inverting amplifier, and a voltage comparator to implement the short-circuit protection function. Specifically, a sampling resistor is used to sample the current signal, the voltage follower isolates it, and then the non-inverting amplifier amplifies it by a predetermined factor. The voltage comparator then compares the amplified input voltage with a set threshold. If the threshold is exceeded, a short-circuit signal is finally output. The short-circuit signal is input to the synchronous adjustable high-power bipolar pulse power supply main control chip FPGA. After the synchronous adjustable high-power bipolar pulse power supply main control chip FPGA detects the rising edge of the short-circuit signal, it shuts off the drive signal of the half-bridge chopper circuit. Finally, the CNC system controls the Z-axis servo motor to drive the tool electrode back to the initial machining gap before power-on machining is performed.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. The electrochemical processing apparatus of the present invention can achieve processing under neutral electrolyte conditions by applying positive and negative pulse voltages to the moving and stationary vortex disks and performing processing under the action of an eccentric constant speed / variable speed rotation mechanism, thereby obtaining a non-clogging and continuous electrochemical dissolution process and thus achieving better processing and forming accuracy.

[0033] 2. Based on the working principle of a scroll compressor, this invention fully utilizes the continuous "intake, compression, and exhaust" working characteristics of the scroll compressor. It aims to provide a competitive process method for high-quality, high-efficiency, and precision machining of scroll disc profiles. This will undoubtedly promote the advancement of scroll compressor design and manufacturing technology, further reduce the manufacturing cost of fuel cell vehicles, and facilitate their commercial application.

[0034] 3. In terms of processing principle, the electrolytic machining device of the present invention not only eliminates the need for complex superhard "tools" and ordinary electrolytic machining tool cathodes compared with conventional precision milling and ordinary electrolytic machining, but also forms a natural conjugate coupling part after electrolytic machining (i.e., good surface quality, no burrs and flash), similar to "fitting" machining. After machining, the radial clearance of the moving and stationary scrolls can be guaranteed with almost no assembly, eliminating the need for subsequent correction machining processes.

[0035] 4. In terms of processing technology, the electrolytic machining apparatus of this invention fully utilizes the high efficiency and lack of mechanical force inherent in electrolytic machining, making it suitable for machining thin-walled surfaces with low rigidity and minimal or no deformation. More importantly, when conventional electrolytic machining of vortex disk materials using a neutral electrolyte, a passivation film forms on the workpiece surface. While this improves the localization of the machining process, it also increases the machining gap impedance, thus affecting processing efficiency and surface quality. When the passivation film is too thick, it can even hinder normal machining. This invention, however, employs bipolar pulse electrolytic machining. During the reverse current phase, the machining zone switches from anode to cathode. Due to the hydrogen evolution reaction, OH- ions accumulate on the surface, reacting with the passivation film and causing it to rupture, allowing electrolytic machining to continue. Therefore, this invention eliminates the need to add acids, alkalis, or complexing agents to the neutral electrolyte during processing, reducing the safety requirements for process implementation.

[0036] 5. In terms of process measures, the electrolytic machining apparatus of the present invention fully utilizes the working characteristics of the scroll compressor. During machining, the moving scroll and the stationary scroll workpiece (which has undergone roughing and semi-finishing treatment beforehand) perform conjugate "meshing" motion. This causes the electrolyte medium in the machining gap between the workpiece electrode and the tool electrode to generate a circulating "self-absorption-compression-discharge" phenomenon, forming a natural converging flow field in the machining gap. Utilizing the resulting tangential discharge characteristics of the chamber pressure difference (forming a high-speed jet in the "meshing" machining gap area of ​​the profile, with a liquid phase flow velocity as high as about 100 m / s), the mass transfer and heat transfer capabilities of the flow field in the electrolytic machining gap can be greatly improved. At the same time, the vortex centrifugal motion of the electrolyte medium (under the action of centrifugal force, the liquid medium is mainly distributed on the outer wall of the working chamber profile) can achieve "natural" flow field constraint in the machining gap. Therefore, it can create favorable conditions for achieving high-quality, high-efficiency, and high-precision electrolytic machining of thin-walled profiles of the scroll. A liquid film is formed in the machining gap of the profile "meshing", which can realize small gap electrolytic machining; as the machining gap gradually increases, the gas content in the gap increases sharply, which is similar to "cutting off" electrolytic machining, thereby effectively improving the machining accuracy. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of leakage and interference in the conjugate meshing of static vortex disks.

[0038] Figure 2 A schematic diagram of the process for self-priming flow field bipolar pulse electrolytic machining of the conjugate profiles of moving and stationary vortex disks.

[0039] Figure 3 A simplified circuit diagram for self-priming flow field bipolar pulse electrolytic machining.

[0040] Figure 4 A schematic diagram of the circuit structure for applying bipolar pulse voltage during machining.

[0041] Figure 5 The waveforms of the gate drive signals for insulated gate bipolar transistors Q1, Q2, Q3, and Q4 are shown.

[0042] In the diagram: 1-Neutral electrolyte, 2-Workpiece electrode, 3-Bubble, 4-Tool electrode, 5-Electrolysis products. Detailed Implementation

[0043] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0044] See Figures 2-5The purpose of this invention is to address the technical challenges of controlling the shape and dimensional accuracy of the thin-walled profiles of the moving and stationary scroll discs of scroll compressors during traditional precision machining. These challenges include severe tool wear, uneven cutting temperature distribution, and stress deformation at thin-walled areas. Additionally, it is difficult to ensure consistent radial clearance when the moving and stationary scroll discs are engaged. This invention is proposed based on the working principle of scroll compressors and fully utilizes their cyclical "intake, compression, and exhaust" characteristics during operation. It aims to provide a competitive process method for high-quality, high-efficiency, and precision machining of scroll disc profiles.

[0045] See Figures 2-5 This invention first utilizes the negative pressure self-priming phenomenon of a scroll compressor during operation to draw in a gas-liquid mixed working medium. Under the pressure difference between the chambers, a high-speed jet is formed in the machining gap of the "meshing" area. A bipolar pulse power supply is activated to control the center distance (0o-0o) between the base circles of the moving and stationary scroll disks. Figure 2 The speed increases at a certain rate, while the moving scroll plate rotates eccentrically around the base circle center of the stationary scroll plate. The rotational speed is adjustable, similar to the working process of a scroll compressor. Bipolar pulse voltage is used to gradually remove the profiles of the moving and stationary scroll plates (removing approximately 200μm). After processing, the power is turned off, and the electrolyte inlet switch is switched to ambient gas. The self-drawn ambient air is used to remove the electrolyte remaining in the moving and stationary scroll plates, further accelerating the electrolyte renewal and improving the efficiency of product discharge and processing efficiency.

[0046] See Figures 2-5 The electrolytic machining apparatus for the bipolar power supply electrolytic machining scroll disk of the present invention includes an electrolytic cell, a tool electrode and a workpiece electrode disposed within the electrolytic cell, a circuit system, and an eccentric constant-speed / variable-speed rotation mechanism for driving the tool electrode to rotate around the Z-axis, wherein...

[0047] The electrolytic cell contains a neutral electrolyte; the stationary vortex disk and the moving vortex disk to be processed constitute the workpiece electrode and the tool electrode, respectively; the workpiece electrode is divided into workpiece electrode-stationary vortex disk and workpiece electrode-moving vortex disk; the tool electrode is divided into tool electrode-moving vortex disk and tool electrode-stationary vortex disk; the stationary vortex disk and the moving vortex disk are in a conjugate meshing state; wherein, the inlet and outlet of the stationary vortex disk and the moving vortex disk in the conjugate meshing state are both connected to the neutral electrolyte in the electrolytic cell; in this embodiment, the inlet and outlet of the stationary vortex disk and the moving vortex disk in the conjugate meshing state are both connected to the neutral electrolyte in the electrolytic cell through a pipeline, wherein a delivery pump is provided on the pipeline between the inlet and the neutral electrolyte in the electrolytic cell;

[0048] The circuit system includes a first circuit system and a second circuit system, wherein...

[0049] The first circuit system includes an adjustable DC power supply E1, an insulated gate bipolar transistor Q1, and an insulated gate bipolar transistor Q2. The positive terminal of the adjustable DC power supply E1 is connected in sequence to the insulated gate bipolar transistor Q1 and the workpiece electrode-static vortex disk in the electrolytic cell. The negative terminal of the adjustable DC power supply E1 is connected to the tool electrode-moving vortex disk in the electrolytic cell.

[0050] The second circuit system includes an adjustable DC power supply E2, an insulated-gate bipolar transistor (IGBT) Q3, and an IGBT Q4. The positive terminal of the adjustable DC power supply E2 is connected in sequence to the IGBT Q3 and the workpiece electrode (moving scroll plate) in the electrolytic cell. The negative terminal of the adjustable DC power supply E2 is connected to the tool electrode (stationary scroll plate) in the electrolytic cell. A current-limiting resistor R is added to the negative terminal line of the IGBT Q4 and the adjustable DC power supply E2.

[0051] The eccentric constant speed / variable speed rotation mechanism is used to drive the tool electrode-moving scroll or the tool electrode-stationary scroll to perform conjugate meshing motion.

[0052] See Figures 2-5 The electrolytic machining apparatus of the bipolar power supply electrolytic machining scroll of the present invention further includes a vertical adjustment mechanism for adjusting the gap between the tool electrode and the workpiece electrode; the vertical adjustment mechanism is a Z-axis servo motor, which is used to drive the tool electrode to make vertical movements.

[0053] See Figures 2-5 The electrolytic machining method of the bipolar power supply electrolytic machining scroll disk of the present invention adopts the electrolytic machining device of the bipolar power supply electrolytic machining scroll disk. During the machining process, the eccentric constant speed / variable speed rotation mechanism drives the tool electrode to perform eccentric rotation, which causes the moving scroll disk and the stationary scroll disk to be machined to perform conjugate meshing motion. This causes the electrolyte in the machining gap between the workpiece electrode and the tool electrode to generate a circulating self-absorption-compression-discharge phenomenon, thereby causing a convergent flow field to be formed in the machining gap. The resulting chamber pressure difference tangential discharge characteristics are used to improve the mass transfer and heat transfer capacity of the flow field in the electrolytic machining gap. Under the action of the chamber pressure difference, a high-speed jet is formed in the machining gap of the meshing area between the moving scroll disk and the stationary scroll disk to discharge the machining product.

[0054] During the processing, positive and negative pulse voltages are alternately applied to the moving and stationary scroll disks, and under the drive of the eccentric constant / variable speed rotation mechanism, continuous and non-clogging electrochemical dissolution of the moving and stationary scroll disks is achieved.

[0055] During the positive pulse voltage tp, insulated-gate bipolar transistors Q1 and Q4 are turned on under the control of drive signals G1 and G4, respectively; insulated-gate bipolar transistors Q2 and Q3 are turned off under the control of drive signals G2 and G3, respectively; at this time, the workpiece electrode-moving scroll is subjected to a high level from the adjustable DC power supply E1, while the tool electrode-stationary scroll is grounded; an electrolytic machining circuit is formed between the workpiece electrode-moving scroll and the tool electrode-stationary scroll; under the action of the positive pulse voltage U1, the electrolytic machining circuit generates a machining current I1, and Al on the surface of the workpiece electrode-moving scroll undergoes a dissolution reaction; while hydrogen evolution occurs on the tool electrode-stationary scroll.

[0056] During the negative pulse voltage tn, insulated-gate bipolar transistors Q1 and Q4 are turned off under the control of drive signals G1 and G4, respectively, while insulated-gate bipolar transistors Q2 and Q3 are turned on under the control of drive signals G2 and G3, respectively. At this time, the workpiece electrode-moving scroll is grounded, and the tool electrode-stationary scroll is subjected to a high level from the adjustable DC power supply E2. An electrolytic machining circuit is formed between the workpiece electrode-moving scroll and the tool electrode-stationary scroll. Under the action of the negative pulse machining voltage U2, the electrolytic machining circuit generates a machining current I2, and the Al on the surface of the tool electrode-stationary scroll... A dissolution reaction occurs; while the workpiece electrode-moving vortex disk undergoes a hydrogen evolution reaction; that is, the polarity is reversed during the positive pulse voltage, the tool electrode becomes the workpiece electrode, and the workpiece electrode becomes the tool electrode; the electrochemical reaction that occurs at this time is the same as that during the positive pulse, so that the tool electrode and the workpiece electrode (moving vortex disk, stationary vortex disk) can process each other; that is to say, during the electrolytic machining process, whether it is during the positive pulse period or the negative pulse period, the workpiece is being processed (the workpiece electrode during the positive pulse, and the workpiece electrode during the negative pulse period is the tool electrode during the positive pulse), thereby transforming the tool electrode wear caused by the conventional bipolar pulse period into a beneficial machining process.

[0057] The dissolution reaction is as follows:

[0058] Al→Al 3+ +3e - (1)

[0059] Al 3+ +3OH - →Al(OH)3↓ (2)

[0060] The hydrogen evolution reaction is as follows:

[0061] 2H2O+2e - →H₂↑+2OH⁻ - (3)

[0062] In addition, to prevent the upper and lower bridges from conducting simultaneously, a dead time t is set between the positive pulse period and the negative pulse period. d .

[0063] See Figures 2-5 The synchronously adjustable high-power bipolar pulse power supply main control chip FPGA in the adjustable DC power supply E1 and the adjustable DC power supply E2 uses Altera's Cyclone IV EP4CE6E22C8 to emit ultra-short pulse signals to connect to the G1, G2, G3, and G4 gate drive control ports of insulated gate bipolar transistors Q1, Q2, Q3, and Q4 to achieve the following: Figure 4 The positive and negative pulse switching conduction state shown is that after the ultra-short pulse signal is isolated and driven by the amplification circuit, it controls the insulated gate bipolar transistors Q1, Q2, Q3, and Q4 to chop the DC voltage output by the adjustable DC power supplies E1 and E2, and output adjustable positive and negative pulse voltages.

[0064] in Figure 2 Partial annotations:

[0065] Vf: Longitudinal velocity of the eccentric motion of the moving scroll plate, n: Rotation frequency of the moving scroll plate, T: Rotation period of the moving scroll plate, R: Radius of the stationary scroll plate, r: Radius of the moving scroll plate, Po: Self-suction inlet, AB(δ): Size of the gap between the moving and stationary scroll plates, P1: Self-suction outlet, t: Time.

[0066] See Figures 2-5 The electrolytic machining apparatus incorporates a short-circuit protection circuit. This circuit employs a voltage follower, a non-inverting amplifier, and a voltage comparator to implement short-circuit protection. A sampling resistor samples the current signal, which is then isolated by the voltage follower. The signal is amplified by a predetermined factor by the non-inverting amplifier. The voltage comparator then compares the amplified input voltage with a set threshold. If the threshold is exceeded, a short-circuit signal is output. This short-circuit signal is input to the synchronous adjustable high-power bipolar pulse power supply FPGA. Upon detecting the rising edge of the short-circuit signal, the FPGA shuts off the drive signal of the half-bridge chopper circuit. Finally, the CNC system controls the Z-axis servo motor to return the tool electrode to the initial machining gap before resuming machining.

[0067] This invention combines the working characteristics of a scroll compressor with electrical discharge machining (EDM) technology. During machining, the moving and stationary scroll plates (previously roughed and semi-finished) perform conjugate meshing motions, causing a circulating "self-priming-compression-discharge" phenomenon in the electrolyte medium within the electrode gap. Simultaneously, eccentric rotational motion is combined with the moving and stationary scroll plates (tool electrode and workpiece electrode). By driving the moving scroll plate to perform a small-radius eccentric rotation around the axis of the stationary scroll plate, several gear rings are constantly meshing between the moving and stationary scroll plates (non-contact, with a small gap between the walls of the moving and stationary scroll plates), thus forming several relatively independent crescent-shaped air compression chambers. The meshing point continuously moves along the scroll line, from... This causes continuous, periodic changes in the volume of each compression chamber, constantly cycling through the "intake, compression, and exhaust" process. Furthermore, this invention utilizes bipolar pulse electrolytic machining, where, during the reverse current phase, the machining zone switches from anode to cathode. Due to the hydrogen evolution reaction, OH- ions accumulate on the surface, reacting with and breaking the passivation film on the machining surface, allowing electrolytic machining to continue. This transforms the disadvantages of conventional bipolar electrolytic machining (cathode wear) into the advantage of sustainable machining. Finally, the bipolar electrolytic machining power supply is synchronously controlled with the eccentric constant / variable speed rotation mechanism, ensuring that the tool electrode and workpiece electrode are energized within the machining gap. Electrolytic machining stops when they deviate from the machining gap, thereby improving the surface quality of the machined material.

[0068] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An electrolytic machining apparatus for bipolar power supply electrolytic machining of a scroll plate, characterized in that, It includes an electrolytic cell, a tool electrode and a workpiece electrode disposed within the electrolytic cell, a circuit system, and an eccentric constant-speed / variable-speed rotating mechanism for driving the tool electrode to rotate around the Z-axis, wherein, The electrolytic cell contains a neutral electrolyte; the stationary vortex disk and the moving vortex disk to be processed constitute the workpiece electrode and the tool electrode; wherein, the workpiece electrode is divided into workpiece electrode-stationary vortex disk and workpiece electrode-moving vortex disk; the tool electrode is divided into tool electrode-moving vortex disk and tool electrode-stationary vortex disk; the stationary vortex disk and the moving vortex disk are in a conjugate meshing state; wherein, the inlet and outlet of the stationary vortex disk and the moving vortex disk in the conjugate meshing state are both connected to the neutral electrolyte in the electrolytic cell; The circuit system is used to alternately apply positive and negative pulse voltages to the moving and stationary scroll disks, wherein, under the negative pulse voltage, the tool electrode becomes the workpiece electrode, and the workpiece electrode becomes the tool electrode. The circuit system includes a first circuit system and a second circuit system. The first circuit system includes an adjustable DC power supply E1, an insulated gate bipolar transistor Q1, and an insulated gate bipolar transistor Q2. The positive terminal of the adjustable DC power supply E1 is connected in sequence to the insulated gate bipolar transistor Q1 and the workpiece electrode-static vortex disk in the electrolytic cell. The negative terminal of the adjustable DC power supply E1 is connected to the tool electrode-moving vortex disk in the electrolytic cell. The second circuit system includes an adjustable DC power supply E2, an insulated-gate bipolar transistor (IGBT) Q3, and an IGBT Q4. The positive terminal of the adjustable DC power supply E2 is connected in sequence to the IGBT Q3 and the workpiece electrode (moving scroll plate) in the electrolytic cell. The negative terminal of the adjustable DC power supply E2 is connected to the tool electrode (stationary scroll plate) in the electrolytic cell. A current-limiting resistor R is added to the negative terminal line of the IGBT Q4 and the adjustable DC power supply E2. The eccentric constant speed / variable speed rotation mechanism is used to drive the tool electrode-moving scroll or the tool electrode-stationary scroll to perform conjugate meshing motion, causing the neutral electrolyte in the electrolytic cell to be drawn from the suction port into the machining gap between the stationary scroll and the moving scroll and move along the machining gap, and then discharged from the discharge port.

2. The electrolytic machining apparatus for bipolar power supply electrolytic machining of scroll disks according to claim 1, characterized in that, It also includes a vertical adjustment mechanism for adjusting the gap between the tool electrode and the workpiece electrode.

3. The electrolytic machining apparatus for bipolar power supply electrolytic machining of scroll disks according to claim 2, characterized in that, The vertical adjustment mechanism is a Z-axis servo motor, which is used to drive the tool electrode to move vertically.

4. An electrolytic machining method for a bipolar power supply electrolytic machining scroll disk, characterized in that, An electrolytic machining apparatus for bipolar power supply electrolytic machining of a scroll plate according to any one of claims 1-3; during the machining process, the circuit system is used to alternately apply positive pulse voltage and negative pulse voltage to the moving scroll plate and the stationary scroll plate. At the same time, the eccentric constant speed / variable speed rotation mechanism drives the tool electrode to perform eccentric rotational motion, causing the moving scroll plate and the stationary scroll plate to be machined to perform conjugate meshing motion, so that the neutral electrolyte in the electrolytic cell is drawn into the machining gap between the workpiece electrode and the tool electrode, and moves along the extension direction of the machining gap; under the action of alternately applied positive pulse voltage and negative pulse voltage, the neutral electrolyte electrochemically dissolves both sides of the machining gap; When the neutral electrolyte reaches the outlet, it moves and is compressed within the processing gap to form a high-speed jet, which is discharged and carries out the processed products. The liquid phase flow velocity of the high-speed jet is 100 m / s.

5. The electrolytic machining method for bipolar power supply electrolytic machining of scroll disks according to claim 4, characterized in that, During the positive pulse voltage tp, insulated-gate bipolar transistors Q1 and Q4 are turned on under the control of drive signals G1 and G4, respectively; insulated-gate bipolar transistors Q2 and Q3 are turned off under the control of drive signals G2 and G3, respectively; at this time, the workpiece electrode-moving scroll is subjected to a high level from the adjustable DC power supply E1, while the tool electrode-stationary scroll is grounded; an electrolytic machining circuit is formed between the workpiece electrode-moving scroll and the tool electrode-stationary scroll; under the action of the positive pulse voltage U1, the electrolytic machining circuit generates a machining current I1, and Al on the surface of the workpiece electrode-moving scroll undergoes a dissolution reaction; while hydrogen evolution occurs on the tool electrode-stationary scroll.

6. The electrolytic machining method for bipolar power supply electrolytic machining of scroll disks according to claim 5, characterized in that, During the negative pulse voltage tn, insulated-gate bipolar transistors Q1 and Q4 are turned off under the control of drive signals G1 and G4, respectively, while insulated-gate bipolar transistors Q2 and Q3 are turned on under the control of drive signals G2 and G3, respectively. At this time, the workpiece electrode-moving scroll is grounded, and the tool electrode-stationary scroll is subjected to a high level from the adjustable DC power supply E2. An electrolytic machining circuit is formed between the workpiece electrode-moving scroll and the tool electrode-stationary scroll. Under the action of the negative pulse machining voltage U2, the electrolytic machining circuit generates a machining current I2, and the Al on the surface of the tool electrode-stationary scroll undergoes a dissolution reaction; while the workpiece electrode-moving scroll undergoes a hydrogen evolution reaction.

7. The electrolytic machining method for bipolar power supply electrolytic machining of scroll disks according to claim 6, characterized in that, The dissolution reaction is as follows: The hydrogen evolution reaction is as follows: 。 8. The electrolytic machining method for bipolar power supply electrolytic machining of scroll disks according to claim 7, characterized in that, A dead time t is set between the positive pulse voltage period and the negative pulse voltage period. d .

9. The electrolytic machining method for bipolar power supply electrolytic machining of scroll disks according to claim 5, characterized in that, The FPGA main control chip of the synchronous adjustable high-power bipolar pulse power supply in the adjustable DC power supply E1 and the adjustable DC power supply E2 sends an ultra-short pulse signal to the gate of the insulated gate bipolar transistors Q1, Q2, Q3, and Q4. After being isolated and driven by the amplifier circuit, the ultra-short pulse signal controls the insulated gate bipolar transistors Q1, Q2, Q3, and Q4 to chop the DC voltage output by the adjustable DC power supply E1 and E2, and output adjustable positive and negative pulse voltages.

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