Flying type line electrode electrolysis turning machining method for micron-sized thin-wall revolving body

Abstract

The invention discloses a flying type line electrode electrolysis turning machining method for a thin-wall rotary body structure. The flying type line electrode electrolysis turning machining method comprises the following specific steps that S1, a thin-wall part is installed on a machine tool spindle through a clamp; s2, the cathode filament is fixedly installed in an electrolytic cell; s3, adjusting the positions of the part and the cathode filament through an industrial camera; a preliminary gap is kept; s4, connecting the part with a power supply anode, connecting a cathode wire with a power supply cathode, and forming a closed loop in the electrolyte solution; electrical parameters are input, a machine tool shaft is driven to enable the part to be close to the cathode wire, when the cathode wire makes contact with the workpiece, the workpiece is moved reversely, and the moving distance is the initial gap of machining; and S5, a set of machining electrical parameters (19-20 V, 350-450 ns, 1 Mhz, 0.9-1 [mu] m / s, the initial gap of 4-6 [mu] m and the rotating speed of 2000-3000 r / min) are input again, the machining track is adjusted through the machine tool controller, and the machining process is completed. During machining, the cathode filament and the workpiece are always kept in the initial machining gap for axial feeding, and the cathode filament is always on the surface of the part and does not make contact with the machined area of the material.

Description

Technical Field

[0001] The present invention belongs to the field of electrochemical machining technology, and specifically relates to a flying wire electrode electrolytic turning method for a micron-level thin-walled rotating body. Background Art

[0002] Traditional machining methods are very prone to deformation, friction, chip accumulation and adhesion, scratching of the processed surface during the contact between the tool and the workpiece, resulting in low processing quality and other problems. It has always been a processing challenge for rotating micro-parts with thin walls, especially those with wall thicknesses in the micron level. Traditional micro-turning still has some difficult-to-overcome problems in terms of wall thickness and surface quality, which restricts the application of thin-walled rotating micro-parts and breakthroughs in related new technologies.

[0003] Wire electrode electrolytic machining is a machining method based on the removal of materials by anode dissolution to achieve workpiece forming. A metal wire electrode with a diameter of tens of microns is used as the machining cathode. The wire electrode has a small cross-sectional area, good electric field concentration, no stray corrosion during machining, and good electrode flexibility, high ductility, and good flexibility and operation. The workpiece does not contact the electrode during machining, and has no effect on the machined surface. It has the advantages of good machining surface quality, no residual stress and burrs, no heat-affected zone, a wide range of machining materials, no tool electrode loss, and theoretical machining accuracy up to micro-nano scale. It is particularly suitable for the precision manufacturing of difficult-to-machine materials and complex structures. Summary of the invention

[0004] Based on the drawbacks of the contact method of traditional machining, the present invention proposes a non-contact process method, which is a flying wire electrode electrolytic turning process for thin-walled rotating body structures. This process combines the machining motion form of traditional turning with the characteristics of wire electrode electrolytic machining. It uses a metal wire with a small cross-sectional area as the machining wire electrode, cooperates with small gap control during the machining process, and solves the stray corrosion problem of electrolytic machining by optimizing process parameters, thereby improving the machining accuracy of turning.

[0005] The technical purpose of the present invention is mainly achieved through the following technical solutions: A flying wire electrode electrolytic turning method for a micron-sized thin-walled rotating body, characterized by comprising the following processes: Step S1, workpiece clamping: a thin-walled part is used as a workpiece and is mounted on the electric spindle of a machine tool through a fixture; during the installation process, the installation accuracy can be corrected by a micrometer and the rotation runout error can be adjusted; Step S2, cathode clamping: install the cathode wire on the cathode fixing device, install the cathode fixing device on the fine-tuning connecting rod, fix the cathode wire in the processing area of ​​the electrolytic cell, adjust the installation position online through the industrial camera, rotate the fine-tuning connecting rod, and correct the horizontality of the cathode wire; the industrial computer can zoom in on the area in real time. If the heights of the two ends of the cathode wire remain consistent, it means that the position of the wire has been corrected; Step S3, adjusting the position of the workpiece: in order to facilitate the subsequent machine tool setting operation, the relative position of the workpiece and the cathode wire is adjusted, the machine tool axis is controlled by the industrial computer, and the workpiece is moved to the processing area of ​​the cathode wire. The moving distance can be visually observed. When the distance between the workpiece and the cathode wire is close to the initial gap, the movement is stopped and the initial gap is maintained; after the adjustment, the electrolyte switch is turned on to immerse the workpiece and the cathode wire in the electrolytic cell; Step S4, tool setting during machining: The purpose of tool setting is to set the initial gap for machining. For the initial gap, the workpiece is connected to the positive pole of the power supply as the anode and kept rotating, and the cathode wire is connected to the negative pole of the power supply. At this time, the non-machining electrical signal is input, and the voltage value of this group of electrical signals must ensure that the current intensity does not reach the machining current (usually a voltage value of 2~4V can be selected). The machining surface will not be affected when the power is on. Then the workpiece is fed toward the cathode wire. During the feeding process, the current is observed through an oscilloscope. When the workpiece collides with the cathode wire, the workpiece retreats, and the retreat distance is the initial gap for machining; Step S5, power-on processing: first, the workpiece and the cathode wire reach the position of the initial gap, and an electrical signal is applied to the power supply at this distance to adjust the process parameters; the workpiece remains in a rotating state, and after power is turned on, the cathode wire and the workpiece maintain a constant initial gap, and the cathode wire moves relative to the workpiece in a feed direction parallel to the axis of the workpiece, and the feed distance is the processing length.

[0006] The flying wire electrode electrolytic turning method for micron-level thin-walled rotating bodies is characterized in that the cathode wire is a structure that is retained after a portion of the electrode wire with a circular cross section is cut off in a direction parallel to its axis. The cathode wire can be surface processed to obtain a cathode wire with a non-circular cross-section shape, so as to achieve the effect of adjusting the processing surface.

[0007] The flying wire electrode electrolytic turning method for micron-level thin-walled rotating bodies is characterized in that the initial gap in step S3 is 3-5 mm.

[0008] The flying wire electrode electrolytic turning method for micron-level thin-walled rotating bodies is characterized in that the initial gap of the processing in step S4 and step S5 is 4-6 μm. The initial gap plays a crucial regulatory role in electrolytic processing. An unreasonable initial gap will affect the roughness of the processed surface. If the gap is too large, the processing effect will be weakened and the stray corrosion phenomenon will be serious. If the gap is too small, the surface will cause unstable processing. Experimental research shows that this distance is the optimal solution for processing.

[0009] The flying wire electrode electrolytic turning method for micron-level thin-walled rotating bodies is characterized in that the power signal applied to the workpiece anode in step S4 is: voltage 2-4V, period 1μs, pulse width 500ns, feed speed 20μm / s, and rotation speed 1000r / min. During the tool setting process, a low voltage and fast feed speed can be set, and this process has no effect on the machined surface.

[0010] The flying wire electrode electrolytic turning method for micron-level thin-walled rotating bodies is characterized in that: in step S5, the voltage is 19-20V, the pulse width is 350-450ns, the frequency is 1MHz, the cathode feed speed is 0.9-1μm / s, and the initial machining gap is 4-6μm; the workpiece speed in step S5 is 2000-3000r / min. Through single-factor experimental research on the influence of different parameters on the machining surface morphology, it is concluded that this group of experimental parameters are the preferred machining parameters.

[0011] The flying wire electrode electrolytic turning processing method for micron-level thin-walled rotating bodies is characterized in that: the electrolyte can be circulated and filtered during the processing; that is, the electrolytic cell is divided into two independent areas by the diversion baffle, namely the water inlet area and the water outlet area; the water inlet area is connected to the external water pool through the filter device and the water pump; the water outlet area is connected to the external water pool through the water pipe; when the water level of the water tank exceeds the diversion baffle, it will enter the water outlet area and be recovered through the water outlet pipe. The water pump and the filter are directly connected through the water pipe, and the water source is purified in real time during the processing. The filter element with micron-level filtration accuracy is used to ensure the renewal of the electrolyte in the processing area.

[0012] The flying wire electrode electrolytic turning method for micron-level thin-walled rotating bodies is characterized in that: the material of the selected rotating body parts is precipitation hardened stainless steel, which is a difficult-to-cut, corrosion-resistant, high-strength aerospace stainless steel material; the electrolyte is a sodium nitrate water-based solution with a concentration of 0.1M / L. The preliminary analysis and comparison of sodium chloride, phosphoric acid, and non-aqueous sodium nitrate solutions in the experiment showed that the water-based sodium nitrate solution has good nonlinear characteristics during the processing process, and is a high-quality passive electrolyte, suitable as the processing electrolyte for the parts.

[0013] The beneficial effects of the present invention are: According to the process method provided by the present invention, during the process of flying electrolytic turning, the tool and the workpiece do not contact during the processing, and there is no processing stress, which overcomes the problem of variability of thin walls caused by processing cutting forces. Wire electrodes are used as processing tools, and the preparation process is simple, the processing centering is good, and there is no axial deviation; the electrode wire, as a flexible material, has good ductility and will not damage the processing surface even if it contacts the workpiece; micro-electrolytic processing technology often uses cathode wire as a tool electrode to process flattened patterns, combined with high-frequency nanosecond pulse power supply, small gap matching, optimization of electrolyte and processing parameters and many other methods, which greatly suppresses the stray corrosion phenomenon in the processing process and improves the processing localization. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The flying wire electrode electrolytic turning principle and device schematic diagram (1-1 is the device schematic diagram; 1-2 is a partial enlarged view of the processing area; 1-3 is the electrolytic turning principle diagram) Figure 2 This is a schematic diagram of the tool setting process of flying wire electrode electrolytic turning. (In the figure, T1, T2, T3, and T4 represent different processing moments, W represents the processed workpiece, and Y represents the cathode wire) Figure 3 This is the moving trajectory diagram of the flying wire electrode electrolytic turning Figure 4 Schematic diagram of cathode wire processing (4-1 is the cathode processing principle diagram; 4-2 is the cathode processing schematic diagram) Figure 5 Surface turning diagrams for different electrolytes (5-1 sodium chloride aqueous solution, 5-2 sodium nitrate aqueous solution, 5-3 phosphoric acid aqueous solution, 5-4 sodium nitrate-ethylene glycol) Figure 6 For processing surfaces with dense stripes (18V, 500ns, 1Mhz, 1.5μm / s, initial gap 10μm, 3000r / min) Figure 7 The machined surface after parameter optimization (20V, 450ns, 1Mhz, 1μm / s, initial gap 5μm, 3000r / min) The reference numbers in the figure are: 1. workpiece, 2. cathode wire, 3. cathode fixing device, 5. electrolytic cell, 6. machine tool spindle, 7. machine tool Z axis, 8. machine tool X axis, 9. machine tool Y axis, 10. water pipe, 11. industrial camera, 12. industrial computer, 13. oscilloscope, 14. water pump, 15. water pool, 16. filter, 17. connecting water pipe, 20. fine-tuning connecting rod. DETAILED DESCRIPTION

[0015] The present invention will be further described with reference to the following drawings.

[0016] Figure 1 The device schematic diagram of the flying wire electrode electrolytic turning process mainly includes: 1 workpiece, 2 cathode wire, 3 cathode fixing device, 5 electrolytic cell, 6 machine tool spindle, 7 machine tool Z axis, 8 machine tool X axis, 9 machine tool Y axis, 10 water pipe, 11 industrial camera, 12 industrial computer, 13 oscilloscope, 14 water pump, 15 water pool, 16 filter, 17 connecting water pipe; 20 fine-tuning connecting rod.

[0017] First, the workpiece 1 is installed on the machine tool electric spindle 6, the cathode wire 2 is wound and installed on the cathode fixing device 3, the tension of the cathode wire is adjusted, and the tension of each assembly is balanced by the tensioner device; after installation, the cathode wire is coated with insulating silicone, only a processing area is reserved, and the silicone is waited for to dry naturally, and then the device is rotated on the fine-tuning connecting rod 20 so that it can be placed just in the water inlet processing area of ​​the electrolytic cell 5, and the placement position of the cathode wire is observed online by the industrial camera 11, and the picture is projected on the display screen of the industrial computer 12, and then the fine-tuning connecting rod is rotated to adjust the horizontal position of the cathode wire. After observing that the positions of both ends of the processing area are horizontal, the correction process of the cathode wire is completed. At this time, the three coordinate axes of the machine tool are moved by the industrial computer 12 until the industrial camera can observe that the workpiece and the cathode wire are close to each other, and the operation can be stopped. There is a spacing of about 3~5mm between the cathode wire and the workpiece. It is convenient for the subsequent tool setting operation.

[0018] Open the valve of the water pump 14, the electrolyte is pumped out from the water pool 15, flows through the connecting water pipe 17, passes through the filter 16, and flows into the electrolytic cell 5 through the water pipe 10. The electrolytic cell is divided into two areas. The area near the water inlet 18 is the water inlet area, and the electrolytic processing is carried out in this area. When the liquid level of the electrolyte exceeds the baffle 4, the electrolyte will return to the water pool 15 through the water outlet 19, completing the circulation process.

[0019] The processing area is covered with electrolyte. At this time, the workpiece is connected to the positive pole of the power supply, and the cathode wire is connected to the negative pole of the power supply. A closed circuit is formed between the workpiece, the cathode wire and the electrolyte. Before processing, determine the initial gap between the workpiece and the cathode wire. Power on the power supply and input a set of non-processing electrical parameters, such as (2~4V voltage, 500ns pulse width, 1MHz frequency, speed 1000r / min, feed speed 20μm / s) Move the machine tool Y axis 9 to bring the workpiece close to the cathode wire. The tool setting process is as follows: Figure 2As shown, at time T1, the workpiece W is far away from the cathode wire. As the distance approaches to time T2, the current value of the oscilloscope 13 gradually increases. When the workpiece moves to time T3, the workpiece and the cathode are in contact, and the current short-circuits. It is necessary to adjust the moving direction of the Y axis of the machine tool to move it in the opposite direction away from the cathode wire. At time T4, the reverse movement distance △ can range from 5 to 20 μm. The optimal machining gap is selected through experiments. In the present invention, the preferred minimum machining gap is 4 to 6 μm; like Figure 3 As shown, during the flying electrolytic turning process, the electrode does not undergo radial feed but only moves in the axial direction. Figure 3 The workpiece W is rotating, and the series of circles in the figure represent some trajectories that the cathode wire Y passes through; the initial gap during the processing is always △. Before the processing trajectory moves, a set of electrical parameters for processing are set, voltage (15~20V, frequency 1MHZ, pulse width 300~500ns, rotation speed 1500~3500r / min, feed speed 0.5~1.5μm / s.) Experimentally preferred, the process parameters that have the greatest impact on turning are voltage and feed speed. The voltage range between 19-20V can achieve thin-walled outer side flat precision processing. When it is lower than 15V, the surface removal effect is not obvious, but when it exceeds 20V, the stray corrosion phenomenon of the processed surface is serious. It is also preferred that the pulse width has no effect on the turning process when it is lower than 300ns. Too large parameters are not conducive to the removal of processed products. The feed speed is preferably 0.9~1μm / s; in addition, the increase in speed assists in the discharge of products. Too high a speed will cause vibration and affect the accuracy. 2500-3000r / min is more appropriate; In addition, the effects of different electrolyte solutions on the turning surface were investigated at the beginning of the process. Figure 5-1 ) The stray corrosion phenomenon is most serious in sodium chloride solution, the contour line of the processed surface is blurred, and the removal amount is large, which is not suitable as a processing electrolyte; ( Figure 5-2 )A black "carbonized film" is easily formed on the surface of phosphoric acid processing, which hinders the reaction rate and causes longitudinal cracks on the processed surface; Figure 5-4 ) reacts slowly in the sodium nitrate-ethylene glycol solution, and the processed area will be quickly oxidized and wrapped, making the processed surface rough. In summary, water-based sodium nitrate can be used as a suitable working fluid.

[0020] The cathode wire tool is not limited to cylindrical cross-sections, and tool electrodes with different cross-sectional shapes can be prepared by electrolytic wire cutting. The shapes of cathode wires with different cross-sections will affect the distribution of the processing flow field and electric field. In order to study the influence of cathodes with different cross-sections on the process, the present invention prepares cathode wires with rectangular cross-sections for electrolytic turning.

[0021] First, wind the two wire electrodes on different cathode fixing fixtures, and fix the processing cathode on the moving axis of the machine tool. The placement is as follows: Figure 4 The cathode to be processed is placed in the electrolytic cell 5, the cathode wire A is used as the cathode for processing and connected to the negative pole of the power supply, and the cathode wire B to be processed is used as the positive pole of the power supply for processing the workpiece, and the power supply parameters are adjusted to obtain the following Figure 4-2 The cross-sectional morphology shown in the figure. This area is used as the working area of ​​electrolytic turning to realize the turning process of thin-walled rotating parts.

[0022] In summary, the turning process of the present invention is mainly aimed at but not limited to thin-walled rotating body structures. The above is only the preferred implementation scheme and preferred process parameters for thin-walled rotating body structures of precipitation hardened stainless steel type. It can be applied to special step structures, cone angle structures, solid rotating body structures, and threaded structures. The tool cathode can also be freely processed and modified to prepare spiral and thin-sheet cathode wire tools. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technology and rights protection of the present invention.

Claims

1. A flying wire electrode electrolytic turning method for micron-sized thin-walled rotating bodies, characterized in that The process includes: Step S1, workpiece clamping: a thin-walled part (1) is used as a workpiece and is mounted on a machine tool spindle (6) through a fixture; Step S2, cathode clamping: install the cathode wire (2) on the cathode fixing device (3), install the cathode fixing device (3) on the fine-tuning connecting rod (20), fix the cathode wire in the processing area of ​​the electrolytic cell (5), adjust the installation position online through the industrial camera (11), rotate the fine-tuning connecting rod, and correct the horizontality of the cathode wire; Step S3, adjusting the position of the workpiece: controlling the machine tool axis through the industrial control computer (12), moving the workpiece (1) to the processing area of ​​the cathode wire (2), and maintaining the initial gap; turning on the water pump (14) switch to immerse the workpiece (1) and the cathode wire (2) in the electrolytic cell (5); Step S4, machining tool setting: the workpiece (1) is connected to the positive pole of the power supply and kept in a rotating state, the cathode wire (2) is connected to the negative pole of the power supply, the positive and negative electrodes form a closed loop in the electrolyte, and an electrical signal is input; the workpiece is fed toward the cathode wire, and during the feeding process, the current is observed through an oscilloscope (13), and when the workpiece collides with the cathode wire, the workpiece retreats, and the retreat distance is the initial clearance of the machining; Step S5, power-on machining: first, the workpiece (1) and the cathode wire (2) reach an initial gap position, and the process parameters are selected; the workpiece remains in a rotating state, and after power is turned on, the cathode wire and the workpiece maintain a constant initial gap, and the cathode wire moves relative to the workpiece in a feed direction parallel to the axis of the workpiece, and the feed distance is the machining length.

2. The flying wire electrode electrolytic turning method for a micron-sized thin-walled rotating body according to claim 1, characterized in that: The cathode wire is a structure that is retained after a portion of an electrode wire with a circular cross section is cut off in a direction parallel to its axis.

3. The flying wire electrode electrolytic turning method for a micron-sized thin-walled rotating body according to claim 1, characterized in that: The initial gap in step S3 is 3-5 mm.

4. The flying wire electrode electrolytic turning method for a micron-sized thin-walled rotating body according to claim 1, characterized in that: The initial gap processed in step S4 and step S5 is 4-6 μm.

5. The flying wire electrode electrolytic turning method for a micron-sized thin-walled rotating body according to claim 1, characterized in that: The electrical signal applied to the workpiece anode in step S4 is: voltage 2~4V, period 1μs, pulse width 400~500ns, cathode feed speed 20~30μm / s, and rotation speed 800~1000r / min.

6. The flying wire electrode electrolytic turning method for a micron-sized thin-walled rotating body according to claim 1, characterized in that: In the step S5, the voltage is 19-20V, the pulse width is 350-450ns, the frequency is 1Mhz, the processing feed speed is 0.9-1μm / s, and the initial processing gap is 4-6μm; the workpiece speed in step S5 is 2000-3000r / min.

7. The flying wire electrode electrolytic turning method for a micron-sized thin-walled rotating body according to claim 1, characterized in that: During the processing, the electrolyte can be circulated and filtered; that is, the electrolytic cell (5) is divided into two independent areas by the diversion baffle (4), namely the water inlet area and the water outlet area; the water inlet area is connected to the external water pool (15) through the filtering device (16) and the water pump (14); the water outlet area is connected to the external water pool through the water pipe (10); when the water level of the water tank exceeds the diversion baffle (4), it will enter the water outlet area and be recovered through the water outlet pipe.

8. The flying wire electrode electrolytic turning method for a micron-sized thin-walled rotating body according to claim 1, characterized in that: The electrolyte selected was a sodium nitrate water-based solution with a concentration of 0.1 M / L.

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