GB2537487A

GB2537487A - Electrochemical composite deposition machining method and apparatus using laser light tube as electrode

Info

Publication number: GB2537487A
Application number: GB1604795.3A
Authority: GB
Inventors: Zhang Zhaoyang; Zhang Changtao; Cai Mingxia; Feng Qinyu; Zhou Jianzhong; Huang Lei; Jiang Yujia
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2013-09-23
Filing date: 2014-04-04
Publication date: 2016-10-19
Anticipated expiration: 2034-04-04
Also published as: WO2015039427A1; CN103572341A; GB2537487B; GB201604795D0; CN103572341B

Abstract

The present invention relates to an electrochemical composite deposition machining method and apparatus using a laser light tube as an electrode. A full-beam pulse laser beam is converted to an annular hollow laser beam with zero light intensity at the center by a light beam modulating system; the annular laser is used to irradiate the expansion of plasma; a compression impact is generated on the electrochemical deposition within a non-solid light tube electrode. The deposition stress is removed, the cathode reaction gas is discharged, and the material density is improved; moreover, the deposition reaction can only occur in the center of the light beam where the laser energy is zero, thereby enabling electrochemical composite deposition machining, repairing and surface performance strengthening having high quality and good location-targeting. The present invention belongs to the field of rapid miniature machining and processing, and is suitable for the machining, repairing and surface performance strengthening of miniature high-performance metal parts.

Description

Electrochemical Composite Deposition Machining Method and Apparatus Using Laser Light Tube as Electrode

Technical Field

[0001] The invention relates to the field of micro rapid prototyping, in particular to a manufacturing method and device of hybrid electrochemical deposition with Laser light tube electrode, applying to the processing, repair and surface strengthening of micro high-performance components.

Background of the Invention

[0002] Both laser processing and electrochemical machining belong to nontraditional machining methods and have their own characteristics. Laser processing is using the high energy laser beam as processing energy by focusing the laser beam on the surface of workpiece to produce unique nonlinear effects of light, heat, and mechanics and so on. Electrochemical machining is using the circuit to transmit electricity to the electrodes and using the electrolyte as the conducting medium to produce electrochemical reaction to remove or deposit material in the form of iron.

[0003] During the laser and electrochemical composite processing, laser beam is brought in the electrochemical system. The high power density laser change the electrode status in irradiated area and produce the photo electrochemical effects, thermal chemical effects and mechanical electrochemical effects. Then the current and speed of electrochemical reaction are affected. The manufacturing of workpiece is achieved with the electrochemical and laser composite processing.

[0004] Some research has been made on the laser electrochemical machining (LECM). Chinese Patent CN1919514A, titled Methods and Devices of Hybrid Processing of Laser Beam Machining with Jet Electrochemical Machining, proposed that the material was removed mainly by the photo thermal effect of laser and the surface recast was removed by electrochemical reaction with the hybrid processing which is combined with laser processing and high-speed jet electrochemical machining. About laser electrochemical composite deposition, Chinese Patent CN200910306817, titled Methods and Devices of Electrofonning Combined with Ultrasound Effect and Laser Effect, proposed that the ultrasonic vibration and laser are simultaneously applied in the region selected. The ultrasonic vibration breaks the metal ion groups in the electrolyte, and laser can increase the activity of electroforming metal ion. The cavitation bubble produced by ultrasound generates the reflection and refraction of laser, changing the originally straight-line propagation of the direction laser.

[0005] In the existing laser and electrochemical composite processing technology, the functions of laser are mainly shown by two ways: enhancing electrochemical reaction and inducing electrochemical reaction. But the efficiency of hybrid processing of the laser energy and the electrochemical reaction is not ideal. The thermal effect of laser will vaporize the electrolyte to form anhydrous region and also envelop a layer of vapor barrier on electrode surface, which influence the process of electrochemical deposition.

At the same time, the electrolyte is pushed outward by the expansion of laser plasma, which hinders the localized deposition of mental ion in the processing zones.

Summary of the Invention

[0007] The aim of this invention is proposed a manufacturing method of hybrid electrochemical deposition with Laser light tube electrode. The material density can be improved by this method, and the deposition reaction will only occur in the center of the laser beam where the laser energy is zero. Hybrid electrochemical deposition can achieve the high quality and good locality processing for repairing and surface strengthening of workpiece.

[0008] Another aim of this invention is proposed a device of hybrid electrochemical deposition with Laser light tube electrode. The device use conventional laser, optical transmission instruments and electrochemical deposition device to improve the locality and quality of deposition processing significantly.

[0009] The technical solution employed in the hybrid electrochemical deposition with Laser light tube electrode is that using photo electrochemistry reaction induced by laser irradiation on the surface of electrode to realize the deposition manufacturing of material, which comprises the following steps: 1) Immersing the lower end of the tool anode and the substrate cathode into the electrolyte, connect power supply and keep the electrolyte circulating; 2) The solid Gauss laser beam is modulated into annular hollow laser beam with zero central intensity by beam modulation system; 3) The annular hollow laser beam is focused on the substrate cathode, the tool anode is placed at the center of the annular hollow laser beam, and the annual plasma which induced by laser forms the Laser light tube electrode and expands.

4) Achieving sustained processing on the substrate cathode by moving the substrate cathode.

[0010] Before the step 1), the substrate cathode is sequentially treated with the process of grinding, degreasing, water washing, weak erosion and water washing.

[0011] The beam modulation system consists of regular pyramid lens and negative pyramid lens, and the regular pyramid lens and negative lens have the same refractive index, azimuth angle and cone angle. The inner radius of annular hollow laser beam is rin, rin=d(ctg(y)-tg(a)), wherein, the n of the refractive index, the qi of the azimuth angle, the a of the cone angle, the d of the distance between regular pyramid lens and negative lens and the d of the width of annular hollow laser beam.

[0012] The technical solution employed in the device of hybrid electrochenaical deposition with Laser light tube electrode is that the invention comprises laser output device, beam modulation system and hybrid deposition processing system. The laser output device comprises a laser resonator and a laser controller which controls the laser resonant to produce a gauss laser which will be modulated to an annual hollow laser beam by the beam modulation system. The hybrid deposition processing system includes tool anode, substrate cathode, processing chamber, electrolyte and electrochemical pulse power supply. The tool anode is connected to the positive polarity of the electrochemical pulse power supply, and the substrate cathode is connected to the negative polarity of the electrochemical pulse power supply. The substrate cathode is immersed in the electrolyte in the processing chamber, and the annular hollow laser beam irradiates the substrate cathode through the focus lens. The tool anode is placed in the center of the annular hollow laser beam, and the end of the tool anode is immersed in the electrolyte.

[0013] Further, the device also includes motion and control system. The motion control 30 system is composed of computer, motion control card, X-Y-Z working platform. The computer is connected to the motion control card is connected, the motion control card is connected to the X-Y-Z working platform, and the processing chamber is placed on the X-Y-Z working platform.

[0014] Further, the device also includes solution storage tank aml acid and alkali resistant pump which transports the electrolyte to the processing chamber.

[0015] Further, the temperature of the electrolyte in solution storage tank is 40 to 50 °C; the tool anode is insoluble wire whose diameter is 0.1 to 0.2 mm; the laser controller output pulsed laser, and its parameters are: the single-pulse energy is 0.1 to 1 J, pulse time is 10 ns, the frequency is 1 to 10 Hz and the wavelength is 1064 nm; the output parameters of the electrochemical pulse power supply are: the peak voltage is 2 to 5 v, the pulse frequency is 0.5 to 2 MHz and the pulse width is 500 to 30 ns.

[0016] The invention has the following beneficial effects: (1) The Laser light tube electrode is formed on the periphery of the tool anode by micro processing system which compounds the annual hollow laser beam irradiation and electrochemistry reaction. The insoluble wire electrode whose diameter is only dozens of microns is placed at the center of the annular hollow laser beam, and it does not affect the transmission of the energy of the laser beam, thus ensuring the high efficiency composite of laser irradiation and electrochemical reaction.

[0017] (2) The plasma shock wave front generated by Laser light tube electrode shrouds on the electrode surface to form a dry zone where the electrochemistry reaction will not occur, and the deposition reaction only occurs in the center of the laser beam where the laser energy is zero, improving the selective locality of electrochemistry reaction. [0018] (3) Applying the shock stress generated by the expansion of laser plasma to the region of electrochemistry deposition, the liquid-side mass transfer speed is improved, the deposition stress is reduced, and the relative density of material is reinforced, significantly improving the quality of the laser electrochemical composite deposition processing.

Brief Descriptions of the Drawings

[0019] Fig. 1 is a system diagram of the annual hollow laser beam and electrochemistry composite micro processing; Fig.2 is a conversion diagram of the gauss laser to the annual hollow laser beam; Fig.3 is a schematic diagram of laser electrochemical composite deposition processing; Fig.4 is the example of laser electrochemical composite deposition processing.

The label names in Fig.1 are: 1. Computer, 2. Laser controller, 3. Laser resonator, 5. Negative pyramid lens, 6. Regular pyramid lens, 7. Annual hollow laser beam, 8. Reflecting mirror, 9. Focus lens, 10. Tool anode, 11. Substrate cathode, 12. Processing chamber, 13. X-Y-Z working platform, 14. Solution storage tank, 15. Oscilloscope, 16.

Motion control card, 17. Electrochemical pulse power supply, 18. A mperemeter, 19. Acid and alkali resistant pump, 20. Electrolyte, 21. Shock wave, 22. Deposit

Detailed Description of the Invention

[00201 Electrochemical composite deposition machining method using a laser light tube as electrode will use a light beam modulating system to deal with the output laser of laser device; a full-beam pulse laser beam is converted to an annular hollow laser beam with zero light intensity at the center; compound machining system will combine an annular hollow laser with an annular anode electrochemical tool which is located in the center of the annular hollow laser, it means that a non-solid tube electrode is formed in the periphery of the annular anode electrochemical tool, using the annular laser to irradiate the expansion of plasma, a compression impact is generated on the electrochemical deposition within a non-solid light tube electrode. The deposition stress is removed, the cathode reaction gas is discharged, and the material density is improved. It enables electrochemical composite deposition machining repairing and surface performance strengthening having high quality.

[0021] A light beam modulating system converts a full-beam pulse laser to an annular hollow laser beam with zero light intensity at the center by using two same taper angle lenses which combine a positive pyramid lens with a negative pyramid lens; changing the diameter of the annular hollow laser beam and adjusting the energy gradient distribution of the laser irradiated area, through changing the spatial position of a positive pyramid lens and a negative pyramid lens and the taper angle, matches with the electrochemical electric-filed energy, constructs electrochemical composite deposition machining system combined with laser.

[0022] After an annular hollow laser beam transmits the electrochemical deposition solution, the density of the beam power is so high that it will cause breakdown in the irradiated area, the array plane of the generated annular plasma shock waves, in the periphery of the anode electrochemical tool, forms a non-solid light tube electrode and causes no-water region; meanwhile, it will generate strong micro-convection in the solution which is in the center of the light tube electrode, decreasing concentration polarization and accelerating the speed of convective mass transfer; there is no electrochemical reaction in the annular part, however,a rapid electrochemical reaction in the center, the reaction rate in the inside and outside of the light tube electrode is obvious different, thereby enhancing the nonlinear location-targeting effect of electrochemical reaction obviously. When the laser device outputs periodic pulse laser, periodic light screen effect will happen at the periphery of the electrochemical tool electrode, finally, location-targeted electrochemical composite deposition will be realized.

I00231 Electrochemical composite deposition machining apparatus using a laser light tube as electrode mainly including: Laser output device, Light beam modulating system, Composite deposition machining system, Movement and control system. Laser output device includes laser control device-, laser resonator; Light beam modulating system includes positive pyramid lens and negative pyramid lens; Composite deposition machining system includes anode tool, cathode substrate, machining cavity electrochemical deposition solution, ammeter, electrochemical power supply, reservoir, acid-alkali-resistance pump, oscilloscope, the cathode of pulse power supply will connect with cathode substrate and the anode of pulse power supply will connect with anode tool, there is an ammeter in series used to detect machining electric current among them, the oscilloscope is used to detect pulse waveform of power supply in the machining process. Movement and control system is constituted by computer, motion control card" X-Y-Z working platform.

[0024] Technical solution of the Invention 1) Establishment of light beam modulating and transforming system It will use two same taper angle lenses which combine a positive pyramid lens with a negative pyramid lens; the negative pyramid lens will be in front of the positive pyramid lens, both positive and negative pyramid lens will be coincident with the output light beam axes; and then the direction of light beam will be changed by using reflector, finally, it will be focused by the convex lens.

[0025] 2) Construction of hollow laser beam and electrochemical composite micromachining system An insoluble metal electrode wire is fixed below the center of focusing mirror light path; it is used as anode tool and connects with the cathode of electrochemical high-frequency power supply; meanwhile, there is an ammeter in series used to detect machining electric current among them; a plate metal electrode is used as electrochemical deposition cathode substrate, connecting with the anode of electrochemical high-frequency power supply; at the same time,the output terminal of power supply will connect with digital storage oscilloscope which is used to observe the change of pulse waveform in electrode in machining process. Cathode substructure will be installed and fixed in the machining cavity above the worktable; motion control card will send out instruction to realize X-Y-Z spatial motion by computer.

[0026] 3) When connection between light path and electric circuit is finished, solution circulation system will be stated and the electrochemical deposition solution, prepared in the reservoir, will be transmitted into machining cavity; the cathode substructure and the lower of anode tool will be immersed in the solution and keep the circulation of electrochemical deposition solution in the machining process.

[0027] 4) According to the need of machining, the computer will control the performance parameter of the output light beam, such as single pulse energy, pulse width, frequency, etc. Also, the computer will adjust the output parameter of electrochemical power supply, such as peak voltage, pulse width, frequency, etc. [0028] 5) Laser output device emits a solid gauss laser, it is modulated to an annular hollow laser beam, and focused by convex lens; the annular laser will penetrate the electrochemical deposition solution and irradiate the cathode substructure, annular plasma, induced by laser, forms a light tube electrode, it also caused adiabatic expansion; a compression impact is generated on the electrochemical deposition within an annular hollow laser beam; metal irons will affected by thermal action in the process of deposition crystallization, achieving high material density and small internal stress location-targeted deposition.

[0029] 6) In the machining process of electrochemical composite deposition with laser, motion control card will send out instruction to realize three-dimensional spatial motion by computer; the deposition material is gradually accumulated as required three-dimensional structure with the movement of worktable.

[0030] In the situation that metal parts have been corroded and their shape precision or dimensional precision have been changed, it use laser to remove oxide on the position of corrosion firstly. And then, oxide layer and several materials in this part are removed using the technology of electrochemical localization etching; it activates the cathode substructure and form micro-electrochemical corrosive dent; and then, electrochemical deposition method using a light tube as electrode is used to enabling the position of corrosion repairing and surface performance strengthening, and improve adhesion strength of electrochemical deposition material on the substructure.

[0031] The invention relating to an electrochemical composite deposition machining method using a laser light tube as electrode is carried out by the following apparatus with Fig.l. According to advancing direction of laser beam, the detailed connection of laser device system is that computer 1 send out control instruction to laser control 2 in order to make laser resonator 3 send out gauss laser 4. Gauss laser 4 goes through a negative pyramid lens 5 and a positive pyramid lens 6 in turn, forming an annual hollow laser beam 7; the laser beam 7 goes through reflector 8 and focusing mirror 9 in turn, irradiating the cathode substructure 11. The detailed connection of electrochemical system is that the cathode of electrochemical power supply 17 connects with cathode substructure 11; the anode of electrochemical power supply 17 connects with anode tool 10. There is an ammeter 18 in series among them. Oscilloscope 15 is used to detect pulse waveform of electrochemical power supply 17 in the machining process; cathode substructure 11 is installed in the machining cavity 12; motion control card 16 will send out instruction to control spatial motion of X-Y-Z worktable13 by computer 1. Also, the motion control card 16 controls acid-alkali-resistance pump 19 to transmit electrochemical deposition solution to machining cavity 12.

1-00321 Main process and steps of this invention (1) Modulate the laser beam firstly. Computer 1 send out control instruction to laser control 2 in order to make laser resonator 3 send out solid parallel gauss laser 4 whose single pulse energy 0.1-1J, pulse time lOns, frequency 1-10Hz, wave length 1064nm.

Gauss laser 4 goes through a negative pyramid lens 5 and a positive pyramid lens 6 in turn; energy in the center of gauss laser 4 is refracted and diverged by the negative pyramid lens 5 and the positive pyramid lens 6, forming an approximate parallel annular hollow laser 7 beam with zero light intensity at the center, as is shown in Fig 2. The required refractive index n, azimuth cp and cone angle a of the negative pyramid lens 5 and the positive pyramid lens 6 are all same; radius of incident solid gauss laser 4 is r; the distance of the negative pyramid lens 5 and the positive pyramid lens 6 is adjusted to d; an annular hollow laser 7 meeting the need of machining can be achieved; its width is R and radius of inner loop is rin.

rin = d(ctg(cp) -tg(a)) [0033] (2) Preparation of electrochemical deposition required solution Choose the kind of bath, use distilled water to prepare the solution, and a little additive improving coating properties and deposition rate obviously is joined in the solution. The additive is including anode activator, brightener, leveling agent, alkali metal and alkali metal salt. Anode activator promotes anode activating and current of the beginning passivation of anode; in order to make sure that the anode is in activation and can be dissolved. Brightener and leveling agent is used to improve material quality. Alkali metal and alkali metal salt is used to improve conductivity of electrochemical deposition solution. In order to increase deposition rate in the deposition process, the temperature of reservoir is heated to 40-50°C.

[0034] (3) Construction of an annular hollow laser beam and electrochemical composite micro-machining system According to Fig. 1, electrochemical pulse power supply17 connects with anode tool 10 and cathode substructure 11. An insoluble metal electrode wire whose diameter is 0.1-0.2mm is used as anode tool and fixed below the center of the center of focusing minor light path. Cathode substructure is stainless steel coupon and its size is 30nunX4Onunx lann. Before using it, the treatment method is including grinding, oil removal, washing, weak erosion, washing. Cathode substructure will be installed and fixed in the machining cavity. The output parameter of electrochemical pulse power supply should be regulated, its peak voltage is 2-5V, pulse frequency is 0.5-2MHz, and pulse width is 500-30ns.

[0035] Experiment of laser and electrochemical composite deposition Firstly, Acid-alkali-resistance pump 19 transmits electrochemical deposition solution from reservoir 14 to machining cavity 12. The cathode substructure 11 and the lower of anode tooll0 will be immersed in the solution; the electrochemical deposition solution keeps circulation flow in machining process. After the beginning of electrochemical pulse power supply, metal ions affected by nanosecond pulse current generates an electrochemical reduction reaction on the surface of cathode substructure. At the same time, the laser beam 7 goes through reflector 8 and focusing minor 9 in turn, irradiating the cathode substructure 11. Annular plasma, induced by annular hollow laser beam 7, forms a light tube electrode, it also caused adiabatic expansion 21; a compression impact. is generated on the electrochemical deposition within an annular hollow laser beam 7; metal irons will affected by thermal action in the process of deposition crystallization, achieving high material density and small internal stress location-targeted deposition., as is shown in Fig3. Motion control card 16 will send out instruction to realize three-dimensional spatial motion by computer 1; the depositional bodies 22 are gradually accumulated as required three-dimensional structure with the movement of X-Y-Z worktable 13. An example of simple cylindrical depositional bodies, produced by using electrochemical composite deposition machining method using laser light tube as electrode, is shown in Fig 4.

[003611n the situation that metal parts have been corroded and their shape precision or dimensional precision have been changed, a method of sweeping away rust by laser is used, and pulse laser beam focus and irradiate on the position of corrosion; pulse vibration is generated on the surface of substructure and corrosion particle; when the generated impact force is greater than surface adhesive force of particle, corrosion particle will be detached and removed. Oxide layer and several materials in this part are removed using the technology of electrochemical localization etching; it. activates the cathode substructure and form micro-electrochemical corrosive dent; in order to improve adhesion strength of electrochemical deposition material on the substructure. Finally, electrochemical composite deposition machining method using laser light a tube as electrode repairs corrosion of the part, or deposit corrosion resistance alloy layer to improve surface properties.

[0037] After compositing a laser light tube as electrode generated by the annular hollow laser beam with electrochemical deposition system, thermal shock action happens in the process of ion crystallization; it will improve the electrode reaction rate, decrease the deposition stress and improve the deposition material density. It has high selectivity and machining accuracy, thus achieving high-quality micro localization deposition.

[0038] The described example is the optimal implementation selection of the invention; however, the invention is not limited to the above implementation; in the situation of not departing from the essential content of the invention, technician in this field can make any obvious modifications, substitutions, or modifications belong to the scope of the present invention.

II

Claims

Claims 1. A manufacturing method of hybrid electrochemical deposition with Laser light tube electrode is that using photo electrochemistry reaction induced by laser inadiation on the surface of electrode to realize the deposition manufacturing of material, characterized in that comprising the following steps: I) Immersing the lower end of the tool anode and the substrate cathode into the electrolyte, connect power supply and keep the electrolyte circulating; 2) The solid Gauss laser beam is modulated into annular hollow laser beam with zero central intensity by beam modulation system; 3) The annular hollow laser beam is focused on the substrate cathode, the tool anode is placed at the center of the annular hollow laser beam, and the laser induced annular plasma forms the Laser light tube electrode and expands.4) Achieving sustained processing on the substrate cathode by moving the substrate cathode to.
2. The manufacturing method of hybrid electrochemical deposition with Laser light tube electrode according to claim 1, characterized in that the substrate cathode is sequentially treated with the process of grinding, degreasing, water washing, weak erosion and water washing before the step 1).
3. The manufacturing method of hybrid electrochemical deposition with Laser light tube electrode according to claim 1, characterized in that the beam modulation system consists of regular pyramid lens and negative pyramid lens, and the regular pyramid lens and negative lens have the same refractive index, azimuth angle and cone angle.
4. The manufacturing method of hybrid electrochemical deposition with Laser light tube electrode according to claim 3, characterized in that the inner radius of annular hollow laser beam is rin, rin=d(ctg(w)-tg(o)), wherein, the n of the refractive index, the N' of the azimuth angle, the a of the cone angle, the d of the distance between regular pyramid lens and negative lens and the d of the width of annular hollow laser beam.
5. The device of hybrid electrochemical deposition with Laser light tube electrode, comprising laser output device, beam modulation system and hybrid deposition processing system. The laser output device comprises a laser resonator and a laser controller which controls the laser resonant to produce a gauss laser which will be modulated to an annual hollow laser beam by the beam modulation system. The hybrid deposition processing system includes tool anode, substrate cathode, processing chamber, electrolyte and electrochemical pulse power supply. The tool anode is connected to the positive polarity of the electrochemical pulse power supply, and the substrate cathode is connected to the negative polarity of the electrochemical pulse power supply. The substrate cathode is immersed in the electrolyte in the processing chamber, and the annular hollow laser beam irradiates the substrate cathode through the focus lens. The tool anode is placed in the center of the annular hollow laser beam, and the end of the tool anode is immersed in the electrolyte.
6. The device of hybrid electrochemical deposition with Laser light tube electrode according to claim 5, characterized in that the device also includes motion and control system. The motion control system is composed of computer, motion control card, XY-Z working platform. The computer is connected to the motion control card is connected, the motion control card is connected to the X-Y-Z working platform, and the processing chamber is placed on the X-Y-Z working platform.
7. The device of hybrid electrochemical deposition with Laser light tube electrode according to claim 5, characterized in that the device also includes solution storage tank and acid and alkali resistant pump which transports the electrolyte to the processing 25 chamber.
8. The device of hybrid electrochemical deposition with Laser light tube electrode according to claim 5, characterized in that the temperature of the electrolyte in solution storage tank is 40 to 50 C.
9. The device of hybrid electrochemical deposition with Laser light tube electrode according to claim 5, characterized in that the tool anode is insoluble wire whose diameter is 0.1 to 0.2 mm.
10. The device of hybrid electrochemical deposition with Laser light tube electrode according to claim 5, characterized in that the laser controller output pulsed laser, and its parameters arc: the single-pulse energy is 0.1 to 1.1, pulse time is 10 ns, the frequency is 1 to 10 Hz and the wavelength is 1064 nm; the output parameters of the electrochemical pulse power supply are: the peak voltage is 2 to 5 v, the pulse frequency is 0.5 to 2 MHz and the pulse width is 500 to 30 ns.