CN111299731A - A processing method and control system for forming a microstructure on the surface of a workpiece - Google Patents

Abstract

The invention relates to a processing method for forming a microstructure on the surface of a workpiece, which comprises the following steps: s1, providing a micro rod with a small electrochemical resistance value on the surface, and forming a first microstructure with a large electrochemical resistance value on the surface of the micro rod at a high temperature to obtain a line electrode; and S2, providing the workpiece inserted into the electrolyte as an anode, driving the wire electrode to rotate and driving the wire electrode to rotate around the workpiece, and supplying power to the workpiece and the wire electrode to form a required microstructure on the surface of the workpiece according to the first microstructure on the wire electrode. The wire electrode of the first microstructure with a large electrochemical impedance value on the surface is used as a tool electrode, so that the flexible and controllable preparation of the microstructure array on the surface of the workpiece can be realized, particularly the processing of the microstructure array of a small-caliber rotary surface and a quasi-rotary surface can be realized, in addition, the wire electrode can be repeatedly used, and the processing method is suitable for any curved surface obtained by linear scanning.

Description

A processing method and control system for forming a microstructure on the surface of a workpiece

technical field

The invention relates to a processing method and a control system for forming a microstructure on the surface of a workpiece.

Background technique

Surface microtexturing technology refers to the use of microfabrication methods to construct a series of microstructure arrays with certain shapes, sizes and arrangements on the surface of materials, thereby improving/regulating the surface properties of materials. In recent years, with the development of microfabrication technology, surface microtexture technology has been widely used in bionics, tribology (reducing friction, reducing tool wear and reducing adhesion), microfluidics (reducing drag in microfluidic channels) and biomedicine ( It has been successfully applied in many fields such as improving the biocompatibility of implants, and achieved good results.

At present, surface microstructure array (microtexture) processing technologies mainly include micro-milling, laser processing, abrasive gas jet, electrical discharge machining and mask electrolytic machining. However, the above methods all have certain defects, such as: micro-milling has machining stress and surface residual stress, and it is difficult to achieve texture treatment on the surface of difficult-to-machine materials; both laser machining and EDM surfaces have heat-affected zones, and the surface Poor roughness; abrasive air jets are only suitable for machining brittle materials, etc.

Masked Electrochemical Machining (TMECM) is a special machining process in which the anode surface is subjected to photolithography and then electrolytic machining. One of the common methods for array preparation. In the TMECM process, the fabrication of the mask is a very critical step. At present, the fabrication methods of the mask mainly include the photographic shrinkage method, the electron beam direct writing method and the focused ion beam direct writing method, etc., but these methods are expensive, Disadvantages such as long production cycle and small mask area. Moreover, when the characteristic parameters of the required array structure need to be changed, if the traditional TMECM process is used, the mask must be re-fabricated, which not only causes waste of materials, but also greatly prolongs the process cycle. In addition, the existing mask ECM technology is usually used for the preparation of flat or large-diameter surface microstructure arrays, and it is difficult to achieve small-diameter rotation and quasi-rotation thin-walled surfaces (for example, the inner/outer surface of rotation of cardiovascular stents, Micro-gear, cam and other quasi-revolution contour surface, etc.) microstructure array processing.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a processing method for forming a microstructure on the surface of a workpiece, so as to realize the flexible and controllable preparation of the microstructure array on the surface of the workpiece, especially to realize the cross-scale of the small-diameter rotary surface, the quasi-rotational surface, and the rotary inner surface High-quality flexible processing of microstructured arrays.

In order to achieve the above object, the present invention provides the following technical solutions: a processing method for forming a microstructure on the surface of a workpiece, the method comprising:

S1, providing a micro-rod with a small electrochemical impedance value on the surface, and at a high temperature so that the surface of the micro-rod forms a first microstructure with a large electrochemical impedance value to obtain a wire electrode;

S2. Provide the workpiece inserted into the electrolyte as an anode, drive the wire electrode to rotate and drive the wire electrode to rotate around the workpiece, and supply power to the workpiece and the wire electrode according to the No. A microstructure forms the desired microstructure on the surface of the workpiece.

Further, the first microstructure is obtained by one of laser processing, electron beam processing, chemical and laser processing.

Further, in the S2, an ultra-short pulse power supply is used for power supply.

Further, the duration of the ultra-short pulse may be 50-500 ns, and the pulse period may be 0.1-1 MHz.

Further, the micro rods are metal rods.

Further, the diameter of the metal rod is 0.1-3.0 mm.

Further, the first microstructure is one of a trench type, a quasi trench type, and a lattice type.

Further, the surface of the workpiece is one of a rotary inner surface, a rotary outer surface, a quasi-rotational inner surface, a quasi-rotational outer surface, a plane, and a quasi-plane.

Further, before the high temperature treatment of the micro rods, the method further includes cleaning and drying the micro rods.

The invention also provides a control system for realizing the formation of microstructures on the surface of the workpiece. The processing method for forming the microstructures on the surface of the workpiece is used to process the workpiece set in the electrolyte as an anode. A wire electrode disposed in the electrolyte, a power supply device electrically connected to the wire electrode and the workpiece respectively, the power supply device forms a loop with the wire electrode and the workpiece, wherein the wire electrode is a cathode, The workpiece is an anode.

The beneficial effect of the present invention is that: in the processing method for forming a microstructure on the surface of a workpiece provided by the present invention, a wire electrode with a first microstructure with a large electrochemical impedance value on the surface is used as a tool electrode, and the rotation of the wire electrode is controlled cooperatively. And rotating around the workpiece, using the transient effect of electric double layer charging on the surface of the wire electrode, combined with the difference in electrochemical impedance in the local micro-region of the wire electrode, to achieve selective electrochemical corrosion on the surface of the workpiece, so that the microstructure array on the surface of the workpiece can be realized. Flexible and controllable preparation, especially to realize the processing of small-diameter revolving surface and quasi-revolving surface microstructure array, in addition, the wire electrode can be reused, and the processing method is suitable for any curved surface obtained by linear scanning.

The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, and implement it according to the content of the description, the preferred embodiments of the present invention are described in detail below with the accompanying drawings.

Description of drawings

1 is a flow chart of the processing of the processing method for forming a microstructure on the surface of a workpiece shown in the first embodiment of the present invention;

FIG. 2 is an enlarged view of area A in FIG. 1 , wherein a and b are schematic structural diagrams of the first pattern and the second pattern of two types of wire electrodes;

3 is an enlarged view of area B in FIG. 1 , wherein, c and d are schematic structural diagrams of two workpieces with microstructures, and c is obtained based on a, and d is obtained based on b;

FIG. 4 is a schematic structural diagram of the wire electrode rotating around the workpiece and self-rotating in FIG. 1;

FIG. 5 is a schematic structural diagram of the microstructure formed on the surface of the workpiece based on the wire electrode in FIG. 1 , wherein t1 and t2 are the processing areas of the workpiece at two different times;

为稳态电位；

为阳极工件材料的电化学分解电位；t_on为脉冲持续时间；t_off为脉冲关断时间；6 is the potential waveform curve in FIG. 1, wherein 13 is the pulse voltage waveform; 12 is the potential waveform of the region corresponding to the first pattern; 11 is the potential waveform of the region corresponding to the first pattern; U is the set pulse voltage size;

is the steady-state potential;

is the electrochemical decomposition potential of the anode workpiece material; t _on is the pulse duration; t _off is the pulse off time;

FIG. 7 is a schematic structural diagram of the wire electrode and the workpiece in FIG. 1 , wherein the workpiece is a typical curved surface obtained by scanning a bus bar as a straight line, and e and f are two different views.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

Referring to FIGS. 1 to 3, the present invention provides a control system for forming a microstructure on the surface of a workpiece 5, and a processing method for forming a microstructure on the surface of the workpiece 5 is used to control the workpiece 5 disposed in the electrolyte as an anode. For processing, the control system includes a wire electrode 2 arranged in the electrolyte, a power supply device 6 electrically connected to the wire electrode 2 and the workpiece 5 respectively, and the power supply device 6 forms a loop with the wire electrode 2 and the workpiece 5. In the loop, The power supply device 6 is an ultra-short pulse power supply 6, the duration of the ultra-short pulse can be 50-500 ns, and the pulse period is 0.1-1 MHz. The wire electrode 2 is the cathode, and the workpiece 5 is the anode. The wire electrode 2 is obtained by using a micro rod 1 through high temperature treatment, wherein the micro rod 1 is a metal rod 1, and the diameter of the metal rod 1 is 0.1-3.0 mm. Specifically, what kind of metal is used, and the specific diameter of the metal rod 1 is here. There is no specific restriction, which can be determined according to the actual situation. The electrochemical impedance value of the surface of the fine rod 1 is very small, and the electrochemical impedance value at this time is the electrochemical impedance value inherent to the metal surface of the fine rod 1. After high temperature treatment, a first microstructure with a larger electrochemical impedance value is obtained. 4. The area of the first microstructure 4 can be equivalent to an insulator under the action of ultra-short pulses, that is, the surface of the wire electrode 2 is divided into two parts, the first pattern 3 and the second pattern 4, and the first pattern 3 is a micro rod 1. The original surface without high temperature treatment has a small electrochemical impedance value. The second pattern 4 is the first microstructure 4 of the micro rod 1 after high temperature treatment. The first microstructure 4 can be obtained by laser processing and electron beam processing. , of course, the first microstructure 4 can also be obtained in other ways, which is not specifically limited here.

The above-mentioned control system is used to realize the processing method of forming a microstructure on the surface of the workpiece 5, and the method includes:

S1, providing a micro rod 1 with a small electrochemical impedance value on the surface, and at a high temperature so that the surface of the micro rod 1 forms a first microstructure 4 with a large electrochemical impedance value to obtain a wire electrode 2;

S2, providing the workpiece 5 inserted into the electrolyte as an anode, driving the wire electrode 2 to rotate and driving the wire electrode 2 to rotate around the workpiece 5, and supplying power to the workpiece 5 and the wire electrode 2 according to the first microstructure 4 on the wire electrode 2. The surface of the workpiece 5 forms the desired microstructure.

In the present invention, the first microstructure 4 of the wire electrode 2 is one of a trench type, a quasi trench type, and a lattice type. Of course, the first microstructure 4 can also be of other types, which is not specifically limited here. The wire electrode 2 with the first microstructure 4 on the surface can be reused for many times, thereby reducing the waste of materials and greatly shortening the processing cycle.

It is true that before the high temperature treatment of the fine rods 1, the processing method also includes cleaning and drying the fine rods 1. Specifically, the fine rods 1 are ultrasonically decontaminated with acetone, alcohol and deionized water in sequence, and dried in a vacuum. Dry in box. The obtained wire electrode 2 with the first microstructure 4 on the surface is also subjected to ultrasonic cleaning and is used for subsequent electrolytic processing.

Referring to FIG. 4 , in the preparation of the microstructure on the surface of the workpiece 5, that is, during the electrolytic machining process, the wire electrode 2 not only rotates around its own axis, but also follows the same translation path 9 as the cross-sectional shape of the anode workpiece 5, so that the workpiece 5 The entire surface is machined with the desired microstructure. By cooperatively controlling the rotational angular velocity ω _r of the wire electrode 2 and the translational velocity v _p along the surface of the workpiece 5 , the flexible fabrication of microstructures of different sizes can be achieved.

无法达到工件5的电化学分解电位

因此，在线电极2旋转过程中，阳极工件5表面与第二图案4所对应微区域内的材料不会发生电化学溶解(称为不溶解区8)；而第一图案3部分所对应的区域由于电化学阻抗很小，所形成的双电层充/放电时间常数很小，在脉冲持续时间(t_on)内，双电层的电位能够超过阳极工件5的电化学分解电位

因此，在线电极2旋转过程中，阳极工件5表面与第一图案3所对应微区域内的材料将发生电化学溶解去除(称为溶解区7)，以此得到具有微结构的工件5。Please refer to Fig. 5 and Fig. 6. Under the action of ultra-short pulses, the surface of the wire electrode 2 will produce a transient effect of electric double layer charging and discharging. The area corresponding to the second pattern 4 has a large electrochemical impedance. The electric double layer time constant is also large, resulting in the electric double layer charging potential during the pulse duration

Unable to reach the electrochemical decomposition potential of workpiece 5

Therefore, during the rotation of the wire electrode 2, the surface of the anode workpiece 5 and the material in the micro-area corresponding to the second pattern 4 will not be electrochemically dissolved (referred to as the insoluble area 8); while the area corresponding to the first pattern 3 Due to the small electrochemical impedance, the charge/discharge time constant of the formed electric double layer is very small, and the potential of the electric double layer can exceed the electrochemical decomposition potential of the anode workpiece 5 within the pulse duration (t _on ).

Therefore, during the rotation of the wire electrode 2, the surface of the anode workpiece 5 and the material in the micro area corresponding to the first pattern 3 will be electrochemically dissolved and removed (referred to as the dissolution zone 7), thereby obtaining the workpiece 5 with microstructure.

Please refer to FIG. 7 , the processing method shown in the present invention is suitable for any curved surface whose shape is obtained by linear scanning of the generatrix. , one of the quasi-planes, it can also be other planes, no specific limitation is made here.

In the present invention, the electrolytic machining mainly includes the following steps: firstly, the prepared wire electrode 2 with the first microstructure 4 on the surface is installed on the wire electrode 2 fixture in the micro-electrochemical machining platform, and the axis of the prepared wire electrode 2 is precisely adjusted to match The surface of the anode workpiece 5 is parallel to ensure that the distance between the wire electrode 2 and the workpiece 5 along the axis direction of the wire electrode 2 is the same, that is, the machining gap 10 is the same; then, according to the characteristic size of the microstructure to be processed and the surface shape of the workpiece 5, Set the ECM parameters, including voltage, pulse frequency, pulse duration, the rotation angular velocity ω _r of the wire electrode 2, the translation path 9 of the wire electrode 2 and the translation speed v _p and other parameters, start the ECM, and wait for the end of the processing Then, the first microstructure 4 on the surface of the wire electrode 2 will be transferred to the surface of the anode workpiece 5 in a certain proportion; finally, after the electrolytic machining is completed, the workpiece 5 is ultrasonically cleaned to remove impurities such as electrolyte remaining on the surface. The machining process is over.

Regarding the processing method for forming the microstructure on the surface of the workpiece 5, it will be described below with reference to FIG. 1 and with specific embodiments:

Example 1

Step 1: Using a tungsten rod 1 with a diameter of 1.0 mm, ultrasonically clean it in acetone, alcohol and deionized water for 5 minutes in sequence to remove oil stains and other dust impurities on its surface. Then, it was placed in a vacuum drying oven at 100 °C for 10 min to ensure that the surface was relatively dry.

Step 2. Use the laser scanning processing method to process the above-mentioned tungsten rod 1 to form a first microstructure 4 on its surface to obtain a wire electrode 2, please refer to FIG. 2, wherein the area corresponding to the second pattern 4 is the area of laser processing , the first pattern 3 is the original surface of the tungsten rod, that is, the non-laser processing area. A large amount of oxides will be formed in the laser processing area, and the electrochemical impedance is very large. Under the action of ultra-short pulses, it can be equivalent to an insulator. The specific shape of the first microstructure 4 and the layout on the tungsten rod 1 are determined according to actual needs. , there is no specific restriction here.

Step 3: The wire electrode 2 with the first microstructure 4 on the surface prepared in step 2 is ultrasonically cleaned in acetone, alcohol and deionized water for 5 minutes, and then dried with natural air. The wire electrode 2 is prepared.

Step 4. Install the prepared wire electrode 2 on the wire electrode fixture in the micro-electrochemical machining platform, and the anode workpiece 5 to be processed is a 316L stainless steel tube with an outer diameter of 5.0 mm and a wall thickness of 0.5 mm, which is fixed on the anode fixture. . Accurately adjust the axis of the wire electrode 2 to be parallel to the surface of the anode workpiece 5 to ensure that the machining gap 10 is the same everywhere along the axis of the wire electrode 2 during the machining process. Certainly, the value of the machining gap 10 can also be other, and the range of the machining gap 10 is 0.001mm-0.005mm, so the value of the machining gap 10 can be determined according to the actual situation, which is not limited here.

Step 5. Set the frequency of the ultra-short pulse power supply 6 to 1MHz, the ultra-short pulse duration t _on to be 200ns, the rotation angular velocity ω _r of the wire electrode 2 to be 0.1rad/s, and the translation path 9 to be set to be concentric with the 316L stainless steel tube The radius of the circle is the sum of the diameter of the wire electrode 2, the diameter of the workpiece 5 and the machining gap, that is, 2.5mm+0.003mm+0.5mm, the translation speed v _p is 0.01mm/s, after the electrolytic machining is completed, the anode workpiece 5. The required microstructures are formed on the surface, as shown in FIG. 3 for details. The specific values of the rotational angular velocity ω _r and the translational velocity v _p of the wire electrode 2 are set according to actual needs, and are not specifically limited here.

Step 6: ultrasonically clean the anode workpiece 5 with microstructures in acetone, alcohol and deionized water for 5 minutes respectively, and the processing is finished.

Embodiment 2

Step 1: The diameter of the tungsten rod 1 is 0.5 mm, and the cleaning and drying methods are the same as those in the first embodiment, which will not be repeated here.

Step 2: Immerse the tungsten rod 1 in a certain concentration of fluorosilane solution for surface fluorination treatment, the temperature is 60°C, and the time is 0.5 hours; take out the tungsten rod 1, and bake it in a vacuum drying oven at 120°C for 1.0 hours , and then cooled naturally in the air environment. After the above process, a molecular film with a thickness of several hundreds of nanometers is formed on the surface of the tungsten rod 1. The molecular film has a large electrochemical impedance. Under the action of ultra-short pulses, it can wait Effective as an insulator. The above-mentioned tungsten rod 1 is processed by a laser scanning processing method to form a first microstructure 4 on its surface, and a wire electrode 2 is obtained, please refer to FIG. The reserved area for the molecular film, that is, the non-laser processing area, has a large electrochemical impedance. The first pattern 3 is the original surface of the tungsten rod 1, that is, the laser processing area. The molecular film is removed and the original surface of the tungsten rod 1 is exposed. The regional electrochemical impedance is small. The specific shape of the first microstructure 4 and the layout on the tungsten rod 1 are determined according to actual needs, and are not limited herein.

Step 3: Clean the wire electrode 2, and the cleaning method is the same as that in the first embodiment, and will not be repeated here.

Step 4. This step in this embodiment is basically the same as the step in Embodiment 1, except that the workpiece 5 is a titanium alloy tube with an outer diameter of 3.0 mm and a wall thickness of 0.2 mm, and the machining gap 10 is 0.002 mm.

Step 5. This step in this embodiment is basically the same as the step in Embodiment 1, except that: the pulse duration t _on of the pulse power supply 6 is set to 100ns, the rotation angular velocity ω _r of the wire electrode 2 is set to 0.2rad/s, The translation path 9 is set as a circle concentric with the titanium alloy tube, the radius of the circle is 1.5mm+0.002mm+0.25mm, and the translation speed v _p is 0.005mm/s.

In step 6, the anode workpiece 5 is ultrasonically cleaned in acetone, alcohol and deionized water for 5 minutes respectively, and the whole processing process is finished.

To sum up, the processing method for forming a microstructure on the surface of a workpiece provided by the present invention uses the wire electrode of the first microstructure with a large electrochemical impedance value on the surface as the tool electrode, and controls the rotation of the wire electrode and the rotation around the workpiece cooperatively. , using the transient effect of electric double layer charging on the surface of the wire electrode, combined with the difference in electrochemical impedance in the local micro-region of the wire electrode, to achieve selective electrochemical corrosion on the surface of the workpiece, so as to realize the flexibility and control of the microstructure array on the surface of the workpiece In particular, the processing of small-diameter revolving surfaces and quasi-revolving surface microstructure arrays can be realized. In addition, the wire electrode can be reused, and the processing method is suitable for any curved surface obtained by linear scanning.

The technical features of the above embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction in the combination of these technical features It is considered to be the range described in this specification.

The above examples only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims (10)

1. a processing method for forming a microstructure on the surface of a workpiece, wherein the method comprises: S1, providing a micro-rod with a small electrochemical impedance value on the surface, and at a high temperature so that the surface of the micro-rod forms a first microstructure with a large electrochemical impedance value to obtain a wire electrode; S2. Provide the workpiece inserted into the electrolyte as an anode, drive the wire electrode to rotate and drive the wire electrode to rotate around the workpiece, and supply power to the workpiece and the wire electrode according to the No. A microstructure forms the desired microstructure on the surface of the workpiece. 2 . The processing method for forming microstructures on the surface of a workpiece according to claim 1 , wherein the first microstructures are obtained by one of laser processing, electron beam processing, chemical processing and laser processing. 3 . 3 . The processing method for forming microstructures on the surface of a workpiece according to claim 1 , wherein, in the step S2 , an ultra-short pulse power supply is used for power supply. 4 . 4 . The processing method for forming microstructures on the surface of a workpiece according to claim 3 , wherein the duration of the ultra-short pulse is 50-500 ns, and the pulse period is 0.1-1 MHz. 5 . 5 . The processing method for forming microstructures on the surface of a workpiece according to claim 1 , wherein the fine rods are metal rods. 6 . 6 . The processing method for forming a microstructure on the surface of a workpiece according to claim 5 , wherein the diameter of the metal rod is 0.1-3.0 mm. 7 . 7 . The method of claim 1 , wherein the first microstructure is one of a groove type, a quasi-groove type, and a lattice type. 8 . 8. The processing method for forming a microstructure on the surface of a workpiece as claimed in claim 1, wherein the surface of the workpiece is a rotary inner surface, a rotary outer surface, a quasi-rotational inner surface, a quasi-rotational outer surface, a plane, a quasi-rotational surface one of the planes. 9 . The method for forming a microstructure on the surface of a workpiece according to claim 1 , wherein, before the high temperature treatment of the fine rod, the method further comprises cleaning and drying the fine rod. 10 . 10. A control system for realizing the formation of microstructures on the surface of the workpiece is characterized in that, using the processing method for forming microstructures on the surface of the workpiece as described in any one of claims 1 to 9, in order to provide The workpiece is processed as an anode in the liquid, and the control system includes a wire electrode arranged in the electrolyte, a power supply device electrically connected to the wire electrode and the workpiece respectively, and the power supply device is connected to the wire electrode. and the workpiece constitutes a circuit, wherein the wire electrode is a cathode, and the workpiece is an anode.

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