A laser and electrolytic composite processing method for eliminating boundary stray corrosion

Abstract

The application discloses a laser and electrolysis combined machining method for eliminating boundary stray corrosion, belongs to the technical field of special machining, and can solve the problem that machining precision and localization are limited due to stray corrosion at a machining interface in the process of machining micro-slots in the prior art. The method comprises the following steps: obtaining machining parameters of a pre-machined inverted taper groove according to machining parameters of a to-be-machined groove structure; machining the inverted taper groove on a workpiece along a center line of the to-be-machined groove structure by using a water-assisted laser machining mode according to the machining parameters of the inverted taper groove; a side wall of the inverted taper groove is used for reflecting electrolyte during laser and electrolysis combined machining; and machining the groove structure on the inverted taper groove by using a laser and electrolysis combined machining mode according to the machining parameters of the to-be-machined groove structure. The application is used for manufacturing micro-slots on a workpiece.

Description

TECHNICAL FIELD

[0001] The application relates to a laser and electrolytic combined machining method for eliminating boundary stray corrosion and belongs to the technical field of special machining. BACKGROUND

[0002] Micro-grooves are typical structures on metal parts and are widely used in the manufacturing of key parts such as automobile parts, molds, aerospace equipment, etc. For example, the groove drag-reducing structure, the end face sealing groove, the special-shaped groove of the fuel nozzle and the micro-groove on the inner wall surface of the automobile cylinder in aerospace equipment. The machining precision and surface quality of the micro-groove have a huge impact on the function, service life and performance of the part.

[0003] With the application of various high-strength and high-hardness difficult-to-machine metal materials in complex parts, the machining of micro-grooves has been challenged. The mechanical machining process mainly based on turning and milling has problems such as large cutting force, high temperature and difficult chip handling, which easily causes tool wear and affects the machining quality and precision consistency. Although laser machining has the advantages of strong adaptability to machining materials and high efficiency, as a thermal machining process, it is easy to form a recast layer and micro-cracks on the machined surface of the workpiece, which affects the performance of the part. The electric spark machining uses a rod or tubular tool electrode to machine groove structures on the surface of conductive materials, which is not limited by the strength and hardness of the material and has the characteristics of high flexibility of milling and ignoring the hardness of the material of electric spark machining. However, electric spark machining uses high-temperature plasma to remove materials, and the machined surface has a recast layer, micro-cracks and a heat-affected zone. Electrochemical machining has the advantages of no recast layer, no heat-affected zone and no tool wear, and is widely used in the machining of aerospace, electronics, biomedical and other fields.

[0004] The electrochemical machining method of groove structures includes mask electrolysis, single-electrode electrolytic milling, electrochemical grinding composite machining and tubular electrode electrolytic milling. Although tubular electrode electrolytic milling uses a metal tube with an insulating outer wall as an electrode and an electrolyte nozzle, it has high machining localization, but there is stray corrosion problem, which affects the machining precision and surface quality and limits the further improvement and application of the technology. Related units have adopted air-assisted, tubular electrode shape and size optimization or coaxial electrolyte suction to optimize the machining precision of the machined groove structure and reduce the degree of stray corrosion at the machining interface. For example, Nanjing University of Aeronautics and Astronautics has reduced the stray corrosion at the edge of the machined groove by controlling the machining parameters and adjusting the electrolyte reflection state, and under suitable parameter conditions, a high-localization groove structure without stray corrosion can be obtained. However, the above optimization methods have poor process applicability and can only achieve fast machining of groove structures with good machining quality under certain specific parameter conditions.

[0005] A laser and tube electrode electrolysis combined machining technology is also provided in the prior art, which can utilize laser, tube electrode electrolysis machining and coupling effect to remove workpiece material efficiently and improve machining precision. However, the technology still cannot control the distribution characteristics of electrolyte on the surface of the workpiece in the process of machining the groove structure, and the machining interface still has stray corrosion phenomenon in the process of machining the micro groove, and the machining precision and locality are limited. SUMMARY

[0006] The application provides a laser and electrolysis combined machining method for eliminating boundary stray corrosion, which can solve the problem of stray corrosion phenomenon of the machining interface in the process of machining the micro groove in the prior art, and the machining precision and locality are limited.

[0007] The application provides a laser and electrolysis combined machining method for eliminating boundary stray corrosion, which comprises the following steps:

[0008] According to the machining parameters of the to-be-machined groove structure, the machining parameters of the pre-machined inverted taper groove are obtained.

[0009] According to the machining parameters of the inverted taper groove, a water-assisted laser machining mode is adopted to machine the inverted taper groove on the workpiece along the center line of the to-be-machined groove structure; and the side wall of the inverted taper groove is used to reflect the electrolyte in the process of laser and electrolysis combined machining.

[0010] According to the machining parameters of the to-be-machined groove structure, a laser and electrolysis combined machining mode is adopted to machine the groove structure on the inverted taper groove.

[0011] Optionally, the machining parameters of the pre-machined inverted taper groove are obtained according to the machining parameters of the to-be-machined groove structure, and specifically, the machining parameters of the pre-machined inverted taper groove are obtained according to the machining parameters of the to-be-machined groove structure.

[0012] According to the machining parameters of the to-be-machined groove structure, the machining parameters of the pre-machined inverted taper groove are obtained through fluid simulation analysis.

[0013] Optionally, the machining parameters of the inverted taper groove include width, depth and taper angle.

[0014] Optionally, the laser and electrolysis combined machining mode is adopted to machine the groove structure on the inverted taper groove, and specifically, the laser and electrolysis combined machining mode is adopted to machine the groove structure on the inverted taper groove by using a layered milling machining process.

[0015] The laser and electrolysis combined machining mode is adopted to machine the groove structure on the inverted taper groove by using a layered milling machining process.

[0016] Optionally, the water-assisted laser machining mode is adopted to machine the inverted taper groove on the workpiece along the center line of the to-be-machined groove structure according to the machining parameters of the inverted taper groove, and specifically, the water-assisted laser machining mode is adopted to machine the inverted taper groove on the workpiece along the center line of the to-be-machined groove structure according to the machining parameters of the inverted taper groove.

[0017] According to the processing parameters of the inverted tapered groove, the water-assisted laser processing function of the laser and electrolytic composite processing device is used to process the inverted tapered groove on the workpiece along the center line of the groove structure to be processed;

[0018] According to the processing parameters of the groove structure to be processed, the groove structure is processed on the inverted tapered groove by using a laser and electrolytic composite processing method, specifically:

[0019] According to the processing parameters of the groove structure to be processed, the groove structure is processed on the inverted tapered groove using the laser and electrolysis composite processing function of the laser and electrolysis composite processing device.

[0020] Optionally, the laser and electrolysis composite processing device includes: a laser unit, an electrolyte unit, a pulse power supply and a liquid inlet chamber;

[0021] The laser unit is used to provide a laser beam;

[0022] The electrolyte unit is connected to the liquid inlet cavity and is used to provide electrolyte to the liquid inlet cavity;

[0023] A light-transmitting window is provided on the top wall of the liquid inlet cavity, and a tube electrode is provided on the bottom wall of the liquid inlet cavity;

[0024] The positive electrode of the pulse power supply is connected to the workpiece, and the negative electrode is connected to the tube electrode;

[0025] After passing through the light-transmitting window, the laser beam is focused on the center of the top surface of the tube electrode; and after coupling with the electrolyte, it is transmitted to the to-be-processed area of ​​the workpiece through the tube electrode.

[0026] Optionally, the laser unit includes a pulse laser, a reflector group and a focusing lens;

[0027] The pulse laser is used to emit a laser beam;

[0028] The reflector group is used to reflect the laser beam to the focusing lens;

[0029] The focusing lens is used to focus the laser beam onto the center of the top surface of the tube electrode.

[0030] Optionally, the electrolyte unit includes a liquid storage tank, a flow meter and a pressure gauge;

[0031] The liquid storage tank is connected to the liquid inlet cavity through a connecting pipe;

[0032] The flow meter and the pressure gauge are arranged on the connecting pipe;

[0033] The flow meter is used to measure the electrolyte flow rate of the connecting pipe;

[0034] The pressure gauge is used to measure the electrolyte pressure in the connecting pipeline.

[0035] Optionally, the laser and electrolysis composite processing device further includes an industrial computer; the industrial computer is used to control the movement of the tube electrode in the z-axis direction;

[0036] The industrial computer is also used to control the movement of the workpiece on the x-axis and the y-axis.

[0037] Optionally, the industrial computer is also used to monitor the machining current of the workpiece.

[0038] The beneficial effects that the present invention can produce include:

[0039] The laser and electrolysis composite processing method for eliminating boundary stray corrosion provided by the present invention is

[0040] By adopting a step-by-step process and combining it with fluid simulation to obtain the machining parameters for the pre-machined inverted tapered groove, the researchers first used electrolyte-assisted laser machining to pre-machine a flow channel with an inverted tapered cross-section (i.e., an inverted tapered groove) on the workpiece surface according to the simulation results. Laser and electrolytic composite machining was then used to complete the machining of the groove structure. During this process, the electrolyte ejected from the tube electrode impinged on the sidewalls of the pre-machined inverted tapered groove and then flowed back into the air along the sidewalls, eliminating the formation of a continuous electrolyte film on the workpiece surface. This method can control the electrolyte flow field distribution during machining, confining the electrochemical reaction to the target machining area, thereby controlling stray corrosion and improving machining accuracy, achieving laser and tube electrode electrolytic composite machining of groove structures without boundary stray corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A flow chart of a laser and electrolytic composite processing method for eliminating boundary stray corrosion provided by an embodiment of the present invention;

[0042] Figure 2 A schematic structural diagram of a laser and electrolytic composite processing device provided in an embodiment of the present invention;

[0043] Figure 3 Schematic diagram of traditional laser and electrolytic composite milling process;

[0044] Figure 4 Schematic diagram of laser and electrolytic composite processing of microgrooves to eliminate boundary stray corrosion provided by an embodiment of the present invention.

[0045] List of parts and reference numerals:

[0046] 1. Reflector assembly; 2. Industrial computer; 3. Focusing lens; 4. Transparent window; 5. Liquid inlet chamber; 6. Tube electrode; 7. Pulse power supply; 8. Workpiece; 9. Liquid storage tank; 10. Flow meter; 11. Pressure gauge; 12. Pulse laser. DETAILED DESCRIPTION

[0047] The present invention is described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.

[0048] The embodiment of the present invention provides a laser and electrolytic composite processing method for eliminating boundary stray corrosion, such as Figure 1 As shown, the method includes:

[0049] Step 101: Obtain processing parameters of a pre-processed inverted tapered groove according to processing parameters of a groove structure to be processed. The processing parameters of the inverted tapered groove include width, depth, and taper angle.

[0050] Step 102: According to the processing parameters of the inverted conical groove, the inverted conical groove is processed on the workpiece 8 along the center line of the groove structure to be processed by water-assisted laser processing; the side wall of the inverted conical groove is used to reflect the electrolyte during laser and electrolytic composite processing.

[0051] Step 103: According to the processing parameters of the groove structure to be processed, a groove structure is processed on the inverted tapered groove by using a laser and electrolytic composite processing method.

[0052] The laser and electrolytic composite processing method for eliminating boundary stray corrosion proposed in the present invention, when processing a groove structure, first, electrolyte-assisted laser processing is used to pre-process a groove with an inverted cone cross-section on the groove structure path on the surface of the workpiece 8, and the width, depth and cone angle of the inverted cone groove are controlled by controlling the laser parameters; then, a complete groove structure is processed by laser and electrolytic composite layered milling processing.

[0053] The above-mentioned laser pre-processing of the inverted conical groove can change the flow field characteristics of the electrolyte. The electrolyte is reflected into the air along the side wall of the inverted conical groove, leaving the processing surface, and cannot form a liquid film on the surface of the workpiece 8, thereby avoiding stray corrosion current in the non-processing area, thereby eliminating the stray corrosion phenomenon around the processing area and improving the accuracy and localization of the processed groove structure.

[0054] The key parameters for the laser pre-machined inverted tapered grooves described above are width W, depth D, and cone angle θ. Through fluid simulation analysis, the influence of different parameters on the electrolyte reflux path and distribution was analyzed, resulting in an optimal structure in which the electrolyte can form a reflected flow into the air without forming an electrolyte film. Furthermore, through process testing, a combination of process parameters that can produce the optimal structure was obtained, allowing the laser to machine a pre-machined inverted tapered groove that meets the requirements. After machining the pre-machined inverted tapered grooves described above, the electrolytic machining power supply was turned on, and the tube electrode 6 was fed in layers, using a combination of laser and electrolytic machining to produce a groove structure that meets the technical requirements.

[0055] In the embodiment of the present invention, according to the processing parameters of the inverted tapered groove, a water-assisted laser processing method is used to process the inverted tapered groove along the center line of the groove structure to be processed on the workpiece 8, specifically:

[0056] According to the processing parameters of the inverted tapered groove, the water-assisted laser processing function of the laser and electrolytic composite processing device is used to process the inverted tapered groove on the workpiece 8 along the center line of the groove structure to be processed;

[0057] According to the processing parameters of the groove structure to be processed, the groove structure is processed on the inverted tapered groove by using a laser and electrolytic composite processing method, specifically:

[0058] According to the processing parameters of the groove structure to be processed, the groove structure is processed on the inverted tapered groove using the laser and electrolysis composite processing function of the laser and electrolysis composite processing device.

[0059] like Figure 2 As shown, the laser and electrolytic composite processing device includes: a laser unit, an electrolyte unit, a pulse power supply 7, and a liquid inlet chamber 5; the laser unit is used to provide a laser beam; the electrolyte unit is connected to the liquid inlet chamber 5 and is used to provide electrolyte to the liquid inlet chamber 5; a light-transmitting window 4 is provided on the top wall of the liquid inlet chamber 5, and a tube electrode 6 is provided on the bottom wall of the liquid inlet chamber 5; the positive electrode of the pulse power supply 7 is connected to the workpiece 8, and the negative electrode is connected to the tube electrode 6; after passing through the light-transmitting window 4, the laser beam is focused to the center of the top surface of the tube electrode 6; after coupling with the electrolyte, it is transmitted through the tube electrode 6 to the area to be processed on the workpiece 8. In practical applications, the light-transmitting window 4 can be a sapphire window or a quartz glass window; the light-transmitting window 4 is used to seal the electrolyte and transmit light.

[0060] The laser unit includes a pulse laser 12 , a reflector group 1 and a focusing lens 3 ; the pulse laser 12 is used to emit a laser beam; the reflector group 1 is used to reflect the laser beam to the focusing lens 3 ; the focusing lens 3 is used to focus the laser beam to the center of the top surface of the tube electrode 6 .

[0061] The electrolyte unit includes a liquid reservoir 9, a flowmeter 10, and a pressure gauge 11. The liquid reservoir 9 is connected to the liquid inlet chamber 5 via a connecting pipe. The flowmeter 10 and pressure gauge 11 are installed on the connecting pipe. The flowmeter 10 is used to measure the electrolyte flow rate in the connecting pipe, and the pressure gauge 11 is used to measure the electrolyte pressure in the connecting pipe. The pressure gauge 11 and flowmeter 10 monitor electrolyte parameters.

[0062] refer to Figure 2As shown, the laser beam is emitted from the pulse laser 12, transmitted through the mirror group 1 to the focusing lens 3, and then coaxially enters the inside of the annular tube electrode 6 after being focused through the sapphire window and the liquid inlet cavity 5. The innermost layer of the tube electrode 6 is a full reflection layer, which simultaneously realizes the full reflection transmission of the laser and the transmission of the electrolyte. The laser and the electrolyte reach the machining area of the workpiece 8 at the same time, and the pre-machining of the inverted taper groove is completed. The electrolyte for electrochemical machining is pressurized and then reaches the liquid inlet cavity 5 through the connecting pipeline at the set pressure value and flow rate. The metal conductive layer in the tube electrode 6 and the workpiece 8 are connected to the cathode and the anode of the pulse power supply 7, respectively.

[0063] When machining a groove structure, the laser first sweeps along the machining path on the surface of the workpiece 8, at which time the electrochemical reaction does not occur. Due to the laser machining characteristics, an inverted taper groove can be machined at the line of the target machining groove structure. After the laser pre-machining is completed, the tube electrode 6 returns to the starting point, at which time the electrolyte is introduced into the tube electrode 6 for laser and electrochemical combined machining. When the electrolyte is sprayed from the tube electrode 6 to the machining area, the flow field is changed to be reflected along the two side walls of the inverted taper groove to the air and away from the machining surface, instead of forming a liquid film on the surface of the workpiece 8. This process is based on the laser and electrochemical combined machining process. By changing the electrolyte flow field distribution, the material removal phenomenon caused by the flow of electrolyte in the non-machining area can be avoided, the electrochemical reaction is limited to the target machining area, the machining of the groove structure is improved in localization, the stray corrosion phenomenon is reduced, and high-precision machining of the groove structure is achieved. When a deep groove needs to be machined, the tube electrode 6 continues to feed along the Z-axis direction. Due to the high machining quality and good perpendicularity of the edge of the groove structure, the electrolyte is sprayed from the tube electrode 6 and hits the bottom of the machining groove. After the electrochemical reaction, the electrolyte moves along the side wall of the machining groove in the opposite direction of the feeding direction of the tube electrode 6, and then leaves the machining area along the machining gap, so that the combined machining of the high-precision deep groove structure can be achieved.

[0064] In the embodiment of the present application, the laser and electrolyte combined machining device further comprises an industrial computer 2. The industrial computer 2 is used to control the movement of the tube electrode 6 in the z-axis direction. The industrial computer 2 is also used to control the movement of the workpiece 8 in the x-axis and y-axis directions.

[0065] Further, the industrial computer 2 is also used to monitor the machining current of the workpiece 8 in real time through a data acquisition card, a Hall sensor and a LabVIEW-based data acquisition program.

[0066] As shown in Figure 3 , Figure 4 The present application is based on the laser and electrolyte combined machining process. By changing the electrolyte flow field distribution, the current distribution is limited to the target machining micro-groove area, the boundary stray corrosion phenomenon is eliminated, and the high-localization machining of the micro-groove structure can be achieved. Figure 4The high-precision processing of the groove structure shown in the figure has no obvious taper at the intersection of the micro groove and the upper surface of the workpiece 8, and the processing side wall is smooth and has no obvious inclination. Figure 3 The entry quality shown is poor, with rounded corners and stray corrosion in the microgroove structure. When deep grooves are required, the tube electrode 6 is machined layer by layer along the axial direction, feeding in layers. Electrolyte is ejected from the tube electrode 6 and impacts the bottom of the machined groove. After the electrochemical reaction is complete, it moves along the sidewalls of the machined groove in the opposite direction of the tube electrode 6 feed direction, leaving the workpiece 8 machining area along the machining gap. This allows for high-quality, well-perpendicular micro-grooving.

[0067] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A laser and electrolytic composite processing method for eliminating boundary stray corrosion, characterized in that: The method comprises: Obtaining the processing parameters of the pre-processed inverted tapered groove according to the processing parameters of the groove structure to be processed; Specifically, according to the processing parameters of the groove structure to be processed, the processing parameters of the pre-processed inverted tapered groove are obtained through fluid simulation analysis; According to the processing parameters of the inverted tapered groove, the inverted tapered groove is processed on the workpiece along the center line of the groove structure to be processed by water-assisted laser processing; the sidewall of the inverted tapered groove is used to reflect the electrolyte during the laser and electrolytic composite processing; According to the processing parameters of the groove structure to be processed, the groove structure is processed on the inverted tapered groove by using a laser and electrolytic composite processing method; the electrolyte is reflected into the air along the side wall of the inverted tapered groove and leaves the processed surface.

2. The method according to claim 1, characterized in that The processing parameters of the inverted tapered groove include width, depth and taper angle.

3. The method according to claim 1, characterized in that The groove structure is formed on the inverted tapered groove by using a laser and electrolytic composite processing method, specifically: The groove structure is machined on the inverted tapered groove by using a layered milling process using a laser and electrolytic composite machining method.

4. The method according to claim 1, wherein According to the processing parameters of the inverted tapered groove, the inverted tapered groove is processed on the workpiece along the center line of the groove structure to be processed by water-assisted laser processing, specifically: According to the processing parameters of the inverted tapered groove, the water-assisted laser processing function of the laser and electrolytic composite processing device is used to process the inverted tapered groove on the workpiece along the center line of the groove structure to be processed; According to the processing parameters of the groove structure to be processed, the groove structure is processed on the inverted tapered groove by using a laser and electrolytic composite processing method, specifically: According to the processing parameters of the groove structure to be processed, the groove structure is processed on the inverted tapered groove using the laser and electrolysis composite processing function of the laser and electrolysis composite processing device.

5. The method according to claim 4, characterized in that The laser and electrolysis composite processing device includes: a laser unit, an electrolyte unit, a pulse power supply and a liquid inlet cavity; The laser unit is used to provide a laser beam; The electrolyte unit is connected to the liquid inlet cavity and is used to provide electrolyte to the liquid inlet cavity; A light-transmitting window is provided on the top wall of the liquid inlet cavity, and a tube electrode is provided on the bottom wall of the liquid inlet cavity; The positive electrode of the pulse power supply is connected to the workpiece, and the negative electrode is connected to the tube electrode; After passing through the light-transmitting window, the laser beam is focused on the center of the top surface of the tube electrode; and after coupling with the electrolyte, it is transmitted to the to-be-processed area of ​​the workpiece through the tube electrode.

6. The method according to claim 5, characterized in that The laser unit includes a pulse laser, a reflector group and a focusing lens; The pulse laser is used to emit a laser beam; The reflector group is used to reflect the laser beam to the focusing lens; The focusing lens is used to focus the laser beam onto the center of the top surface of the tube electrode.

7. The method according to claim 5, characterized in that The electrolyte unit includes a liquid storage tank, a flow meter and a pressure gauge; The liquid storage tank is connected to the liquid inlet cavity through a connecting pipe; The flow meter and the pressure gauge are arranged on the connecting pipe; The flow meter is used to measure the electrolyte flow rate of the connecting pipe; The pressure gauge is used to measure the electrolyte pressure in the connecting pipe.

8. The method according to claim 5, characterized in that The laser and electrolysis composite processing device further includes an industrial computer; the industrial computer is used to control the movement of the tube electrode in the z-axis direction; The industrial computer is also used to control the movement of the workpiece on the x-axis and the y-axis.

9. The method according to claim 8, characterized in that The industrial computer is also used to monitor the machining current of the workpiece.

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