Brush cathode auxiliary double-electrolysis grinding device and method suitable for titanium alloy screw

Abstract

The invention discloses a brush cathode auxiliary double-electrolysis grinding device and method suitable for a titanium alloy screw. The brush cathode auxiliary double-electrolysis grinding device comprises a workpiece electrolysis module, a grinding wheel online electrolysis finishing module and an electrolyte module. According to the method, the screw workpiece and the metal bond grinding wheel serve as electrolytic objects at the same time, online electrolytic finishing machining of the grinding wheel is achieved, electrolytic grinding machining of the workpiece is achieved, and therefore high-precision surface quality and high grinding efficiency are achieved; metal removal mainly depends on an electrochemical effect and a mechanical effect, an anodic oxide film is mainly removed, and a base material of a workpiece is not ground, so that the grinding temperature and the grinding force are reduced, the abrasion of a grinding wheel can be effectively reduced, and meanwhile, the service life of the grinding wheel is prolonged. The brush can take away abrasive dust inside the spiral groove of the screw and attached to the grinding wheel in the double-electrolysis grinding process, adhesive abrasion of the grinding wheel is reduced, and the surface smoothness of a workpiece is improved.

Description

Technical Field

[0001] The invention relates to the technical field of ultra-precision grinding, and in particular to a brush cathode assisted double electrolytic grinding device and method suitable for titanium alloy screws. Background Art

[0002] Titanium alloy screws are widely used in aerospace, medical and marine engineering due to their high strength, low density, excellent corrosion resistance and good plasticity. However, titanium alloy is a typical difficult-to-process material. Its low thermal conductivity and easy sticking to the knife can easily lead to poor surface processing quality during processing. In addition, the large aspect ratio, poor rigidity and complex shape of the screw make the processing of titanium alloy screws very difficult.

[0003] Titanium alloy screws are generally formed by milling or turning, and their surface quality is poor, which is not easy to meet the performance requirements of the machine. Grinding is needed to improve the surface quality. The grinding of titanium alloy screws is generally carried out by metal bond grinding wheels. At present, the main problem faced by titanium alloy screw grinding is that under the combined effect of large grinding force and high grinding temperature, the workpiece material will be transferred to the surface of the grinding wheel, resulting in serious adhesion of the metal bond grinding wheel abrasive grains, causing the surface quality of the screw to deteriorate. Summary of the invention

[0004] The present invention provides a brush cathode-assisted double electrolytic grinding device and method suitable for titanium alloy screws, which take the screw workpiece and the metal-bonded grinding wheel as electrolytic objects at the same time, thereby realizing online electrolytic dressing of the grinding wheel so that the surface of the grinding wheel always has sharp abrasive grains, and realizing electrolytic grinding of the workpiece to generate an easily removable oxide film on the surface of the workpiece, thereby achieving high-precision surface quality and high grinding efficiency; and because metal removal mainly relies on electrochemical action and mechanical action mainly removes the anodic oxide film without grinding the base material of the workpiece, the grinding temperature and grinding force are reduced, and the wear of the grinding wheel can be effectively reduced. At the same time, the brush can take away the grinding chips inside the spiral groove of the screw and adhered to the grinding wheel during the double electrolytic grinding process, thereby reducing the adhesion wear of the grinding wheel and improving the surface finish of the workpiece.

[0005] For the grinding device, the technical solution of the present invention is as follows:

[0006] A brush cathode-assisted dual electrolytic grinding device suitable for titanium alloy screws comprises a workpiece electrolysis module, a grinding wheel online electrolytic dressing module and an electrolyte module; the workpiece electrolytic module comprises a brush, a headstock, a tailstock, an X-axis bed slide and a programmable pulse power supply I; the headstock and the tailstock are correspondingly arranged on the X-axis bed slide that can move laterally to form a workpiece clamping drive device, and the workpiece clamping drive device is used to install the screw workpiece and can drive the screw workpiece to rotate; a brush seat is provided above the X-axis bed slide, and the brush is installed on the brush seat and can be driven to rotate by a power element corresponding to the brush seat; the brush comprises a base and bristles arranged on the base; after the screw workpiece is installed on the workpiece clamping drive device, the bristles of the brush can contact the screw workpiece; the base of the brush is electrically connected to the negative pole of the programmable pulse power supply I, and the positive pole of the programmable pulse power supply I is used to electrically connect the screw workpiece; the grinding wheel online electrolytic dressing module It includes a Z-axis column slide, a metal bond grinding wheel, a copper electrode and a programmable pulse power supply II; the Z-axis column slide is provided with a grinding wheel driving device, and the metal bond grinding wheel is installed on the grinding wheel driving device; the metal bond grinding wheel can be lowered with the Z-axis column slide to fit the surface of the screw workpiece and contact the bristles of the brush; the Z-axis column slide is arranged on the Y-axis feed slide; the copper electrode is correspondingly arranged on the side of the metal bond grinding wheel, and there is a gap between the copper electrode and the metal bond grinding wheel; the copper electrode is electrically connected to the negative pole of the programmable pulse power supply II, and the metal bond grinding wheel is electrically connected to the positive pole of the programmable pulse power supply II; the electrolyte module includes a water tank for storing electrolyte, and the water tank is provided with a liquid supply pump I and a liquid supply pump II, the liquid supply pump I can transport the electrolyte to the contact position between the brush and the screw workpiece through a pipeline, and the liquid supply pump II can transport the electrolyte to the gap between the copper electrode and the metal bond grinding wheel through a pipeline.

[0007] Compared with the prior art, the present invention has the following beneficial effects:

[0008] (1) By setting up a workpiece electrolysis module and a grinding wheel online electrolysis dressing module, both the online electrolysis dressing process of the grinding wheel and the electrolysis grinding process of the workpiece are realized. During the grinding process, the electrolyte supply device continuously delivers electrolyte, and the grinding wheel is connected to the anode of the power supply. The binder on the surface of the grinding wheel is generated into an oxide film by electrolysis and removed by mechanical action with the workpiece, so that the passivated abrasive grains are easy to fall off, exposing the new abrasive grains inside, so that the surface of the grinding wheel always has sharp abrasive grains. At the same time, the workpiece is connected to the anode of the power supply, and the surface of the workpiece is oxidized into an extremely thin oxide film under the action of electrolysis, and is quickly removed by the mechanical action of the grinding wheel, so that high-precision surface quality and high grinding efficiency can be achieved.

[0009] (2) The material removal of the titanium alloy screw mainly relies on electrochemical action, and the mechanical action is mainly to remove the anodized film without grinding the base material of the workpiece. This can effectively reduce the grinding force and grinding temperature, reduce the adhesion of titanium alloy to the grinding wheel abrasive caused by the direct grinding of the titanium alloy base by the grinding wheel, and reduce the adhesion wear of the grinding wheel.

[0010] (3) By introducing the brush metal matrix as the cathode of the workpiece electrolysis, the brush bristles can remove the grinding chips inside the spiral groove of the titanium alloy screw and adhering to the abrasive grains of the grinding wheel, further reducing the adhesion wear of the grinding wheel. It can prevent the grinding chips from adhering to the abrasive grains of the grinding wheel and coming into secondary contact with the screw surface and falling off on the grinding surface to form spot-like and tongue-like coatings, effectively improving the surface finish of the workpiece.

[0011] (4) The titanium alloy screw has a relatively large length-to-diameter ratio and poor rigidity, which will generate vibration during the grinding process and affect the processing accuracy. The bristles of the brush have good elasticity and buffering properties, which can absorb and disperse the vibration energy to a certain extent, achieving the effect of vibration reduction.

[0012] Furthermore, the base of the brush is a disc body of iron-based material, the bristles are densely distributed on the cylindrical surface of the base, the bristles are pig bristles, the length of the bristles is 5-35 mm, and the density of the bristles is 200-500 pieces / cm². Using pig bristles as the bristles of the brush can make the brush have good elasticity and buffering performance.

[0013] Furthermore, the gap between the copper electrode and the metal bond grinding wheel may be 0.02-0.1 mm.

[0014] Furthermore, the copper electrode is provided with a liquid supply hole, and the liquid supply pump II is connected to the liquid supply hole through a pipeline. During processing, the electrolyte enters the gap between the copper electrode and the metal bond grinding wheel through the liquid supply hole.

[0015] Furthermore, the water tank is connected to the electrolyte recovery tank through a reflux pipeline, and the X-axis bed slide is arranged in the electrolyte recovery tank. Furthermore, a filtering device is arranged on the reflux pipeline. During processing, the electrolyte falls into the electrolyte recovery tank and then flows back to the water tank to achieve recycling.

[0016] Furthermore, the brush base is arranged on a brush adjustment guide rail, thereby the position of the brush can be adjusted to meet the processing requirements of screws of different specifications.

[0017] For the grinding method, the technical solution of the present invention is as follows:

[0018] A brush cathode assisted double electrolytic grinding method for a titanium alloy screw, the method uses the brush cathode assisted double electrolytic grinding device to perform grinding, the steps are as follows:

[0019] Step 1: Fix one end of the titanium alloy screw in the headstock and the other end in the tailstock; adjust the position of the metal bond grinding wheel to fit the titanium alloy screw;

[0020] Step 2: Start the liquid supply pump II to fill the gap between the metal bond grinding wheel and the copper electrode with electrolyte; control the metal bond grinding wheel to start rotating, turn on and adjust the relevant parameters of the programmable pulse power supply II to the set values, perform pre-sharpening, and form an oxide film;

[0021] Step 3, control the brush to rotate, start the liquid supply pump I to fill the space between the titanium alloy screw and the brush base with electrolyte; the titanium alloy screw rotates under the drive of the workpiece clamping drive device, turn on and adjust the relevant parameters of the programmable pulse power supply I to the set value; the titanium alloy screw is cyclically fed through the X-axis bed slide, and the metal bond grinding wheel is positively micro-fed through the Y-axis feed slide; during the grinding process, the surface material of the metal bond grinding wheel is ionized and dissolved, so that the abrasive grains protrude, and at the same time, an oxide film is generated on the surface of the metal bond grinding wheel. As the grinding proceeds, the oxide film is removed under the mechanical action of the titanium alloy screw, so that the passivated abrasive grains are easy to fall off, exposing the new abrasive grains inside, so that the surface of the metal bond grinding wheel always has sharp abrasive grains, and the metal bond grinding wheel can be online dressed; at the same time, the surface of the titanium alloy screw is oxidized into an oxide film under the action of electrolysis, and is removed by the metal bond grinding wheel, exposing a new surface, and continues to be electrolyzed;

[0022] Step 4: After the processing of step 3 reaches the set time, turn off the programmable pulse power supply I, stop the electrolytic titanium alloy screw, and stop the positive micro-feed of the metal bond grinding wheel in the Y-axis direction; use the oxide film on the surface of the metal bond grinding wheel to polish the titanium alloy screw;

[0023] Step 5. After the processing of step 4 reaches the set value, turn off the programmable pulse power supply II, stop the cyclic feeding of the titanium alloy screw in the X-axis direction, withdraw the metal bond grinding wheel, and stop the rotation of the titanium alloy screw and the brush; loosen the headstock and tailstock, and remove the titanium alloy screw.

[0024] Compared with the prior art, the method of the present invention adopts a brush cathode assisted double electrolytic grinding device to grind the titanium alloy screw according to specific steps, has high processing efficiency, and has good surface quality of the titanium alloy screw after processing.

[0025] Furthermore, the electrolyte composition includes: 5-10wt.% sodium nitrate, 2-5wt.% sodium molybdate, 2-5wt.% sodium silicate, 1-3wt.% propylene glycol, 1-2wt.% sodium chloride, and the balance is deionized water. The electrolyte can be used for online electrolysis of metal bond grinding wheels, and has good film-forming performance during the electrolysis of workpieces, good electrical conductivity and cooling performance, as well as good passivation and rust prevention performance, and can take away grinding chips to prevent channel clogging.

[0026] Furthermore, in step three, the feed rate of the metal bond grinding wheel in the positive direction of the Y axis can be 1 μm / min-3 μm / min.

[0027] Furthermore, the relevant parameters of the programmable pulse power supply II include output voltage, duty cycle and internal resistance; in step 2, the output voltage is set to 45-90 V, the duty cycle is set to 0.5-0.8, and the internal resistance is set to 5-300 Ω.

[0028] Furthermore, the relevant parameters of the programmable pulse power supply I include output voltage, duty cycle and internal resistance; in step three, the output voltage is set to 10-30 V, the duty cycle is set to 0.5-0.8, and the internal resistance is set to 5-300 Ω. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a brush cathode assisted double electrolytic grinding device suitable for titanium alloy screws in the present invention;

[0030] Figure 2 It is a structural schematic diagram of an online electrolytic dressing module of a brush cathode assisted double electrolytic grinding device suitable for titanium alloy screws in the present invention.

[0031] Figure markings: 1-brush; 2-headstock; 3-tailstock; 4-X-axis bed slide; 5-programmable pulse power supply I; 6-Y-axis feed slide; 7-Z-axis column slide; 8-metal bond grinding wheel; 9-copper electrode; 901-liquid supply hole; 10-programmable pulse power supply II; 11-water tank; 12-liquid supply pump I; 13-liquid supply pump II; 14-brush holder; 15-universal elbow; 16-electrolyte recovery tank; 17-brush adjustment guide rail. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but is not intended to be limiting of the present invention. The contents not described in detail below or the structures not shown in the accompanying drawings are all common technical knowledge in the art.

[0033] Example (see Figure 1-2 ):

[0034] A brush cathode-assisted dual electrolytic grinding device suitable for titanium alloy screws comprises a workpiece electrolytic module, a grinding wheel online electrolytic dressing module and an electrolyte module; during processing, the workpiece electrolytic module causes the screw workpiece to undergo an anodic reaction, and the grinding wheel online electrolytic dressing module causes the grinding wheel to undergo an anodic reaction.

[0035] In the embodiment, the workpiece electrolysis module includes a brush 1, a headstock 2, a tailstock 3, an X-axis bed slide 4 and a programmable pulse power supply Ⅰ5; the headstock 2 and the tailstock 3 are correspondingly arranged on the X-axis bed slide 4 which can move laterally to form a workpiece clamping drive device, and the workpiece clamping drive device is used to install the screw workpiece and can drive the screw workpiece to rotate; a brush seat 14 is provided above the X-axis bed slide 4, and the brush 1 is installed on the brush seat 14, and can be driven to rotate by a power element corresponding to the brush seat 14; the brush 1 includes a base and bristles arranged on the base; after the screw workpiece is installed on the workpiece clamping drive device, the bristles of the brush 1 can contact the screw workpiece; the base of the brush 1 is electrically connected to the negative pole of the programmable pulse power supply Ⅰ5, and the positive pole of the programmable pulse power supply Ⅰ5 is used to electrically connect the screw workpiece.

[0036] In the embodiment, the grinding wheel online electrolytic dressing module includes a Z-axis column slide 7, a metal bond grinding wheel 8, a copper electrode 9 and a programmable pulse power supply II 10; the Z-axis column slide 7 is provided with a grinding wheel driving device, and the metal bond grinding wheel 8 is installed on the grinding wheel driving device; the metal bond grinding wheel 8 can be lowered with the Z-axis column slide 7 to fit with the surface of the screw workpiece and contact with the bristles of the brush 1; the Z-axis column slide 7 is arranged on the Y-axis feed slide 6; the copper electrode 9 is correspondingly arranged on the side of the metal bond grinding wheel 8, and there is a gap between the copper electrode 9 and the metal bond grinding wheel 8; the copper electrode 9 is electrically connected to the negative pole of the programmable pulse power supply II 10, and the metal bond grinding wheel 8 is electrically connected to the positive pole of the programmable pulse power supply II 10.

[0037] In the embodiment, the electrolyte module includes a water tank 11 for storing electrolyte, and the water tank 11 is provided with a liquid supply pump I12 and a liquid supply pump II13. The liquid supply pump I12 can transport the electrolyte to the contact position between the brush 1 and the screw workpiece through a pipeline, and the liquid supply pump II13 can transport the electrolyte to the gap between the copper electrode 9 and the metal bond grinding wheel 8 through a pipeline.

[0038] In the embodiment, the base of the brush 1 is a disc body of iron-based material, the bristles are densely distributed on the cylindrical surface of the base, the bristles are pig bristles, the length of the bristles is 20 mm, and the density of the bristles is 400 pieces / cm². Using pig bristles as the bristles of the brush 1 can make the brush 1 have good elasticity and buffering performance, and can also absorb and disperse vibration energy to a certain extent, achieving a vibration reduction effect.

[0039] In the embodiment, the gap between the copper electrode 9 and the metal bond grinding wheel 8 is 0.06 mm.

[0040] In the embodiment, the copper electrode 9 is provided with a liquid supply hole 901, and the liquid supply pump II 13 is connected to the liquid supply hole 901 through a pipeline. During machining, the electrolyte enters the gap between the copper electrode 9 and the metal bond grinding wheel 8 through the liquid supply hole 901.

[0041] In the embodiment, the water tank 11 is connected to the electrolyte recovery tank 16 through a reflux pipeline, and the X-axis bed slide 4 is arranged in the electrolyte recovery tank 16; a filter device is arranged on the reflux pipeline. The electrolyte recovery tank 16 and the reflux pipeline are used to transport the electrolyte back to the water tank 11, so as to achieve the purpose of recycling the electrolyte and save processing costs.

[0042] In the embodiment, the metal bond grinding wheel is provided with a grinding wheel cover (in the attached figure, the grinding wheel cover is not drawn in order to clearly show the copper electrode 9), the copper electrode 9 is mounted on the grinding wheel cover, and the grinding wheel cover is connected to the Z-axis column slide 7. The provision of the grinding wheel cover can prevent liquid splashing during the grinding process.

[0043] In the embodiment, the brush holder 14 is arranged on a brush adjustment rail 17 which is in the same direction as the Y-axis feed slide 6 , and the position of the brush 1 can be adjusted through the brush adjustment rail 17 .

[0044] In the embodiment, the liquid supply pump I 12 is connected to the universal elbow 15 through a pipeline. During processing, the electrolyte is transported to the contact part between the brush 1 and the screw workpiece through the universal elbow 15.

[0045] See also Figure 1-2 In this embodiment, the titanium alloy screw is ground. In this embodiment, the brush cathode assisted double electrolytic grinding method of the titanium alloy screw has the following steps:

[0046] Step 1: Fix one end of the titanium alloy screw in the headstock 2, and the other end in the tailstock 3; adjust the position of the metal bond grinding wheel 8 to fit the titanium alloy screw;

[0047] Step 2: Start the liquid supply pump II 13 to fill the gap between the metal bond grinding wheel 8 and the copper electrode 9 with electrolyte; control the metal bond grinding wheel 8 to start rotating at a speed of 1500 rpm, turn on and adjust the relevant parameters of the programmable pulse power supply II 10, including an output voltage of 60 V, a duty cycle of 0.6, and an internal resistance of 200 Ω, perform pre-sharpening for 15 min, and form an oxide film;

[0048] Step 3, control the brush 1 to rotate at a speed of 150 rpm, start the liquid supply pump Ⅰ12 to fill the electrolyte between the titanium alloy screw and the base of the brush 1; the titanium alloy screw is driven by the workpiece clamping drive device to rotate at a speed of 50 r / min; turn on and adjust the relevant parameters of the programmable pulse power supply Ⅰ5, including output voltage 15 V, duty cycle 0.5, and internal resistance 200 Ω; the titanium alloy screw is cyclically fed through the X-axis bed slide 4. The X-axis bed slide 4 makes a back and forth feeding motion to achieve repeated grinding of the spiral groove of the titanium alloy screw as a whole, and the metal bond grinding wheel 8 is positively micro-fed through the Y-axis feed slide 6, with a feed rate of 2μm / min, and the dynamic grinding time is 25 min; During the grinding process, the material on the surface of the metal bond grinding wheel 8 is ionized and dissolved, causing the abrasive grains to protrude, and at the same time, an oxide film is generated on the surface of the metal bond grinding wheel 8. As the grinding progresses, the oxide film is removed under the mechanical action of the titanium alloy screw, making the passivated abrasive grains easy to fall off, exposing new abrasive grains inside, so that the surface of the metal bond grinding wheel 8 always has sharp abrasive grains, realizing the online dressing of the metal bond grinding wheel 8; At the same time, the surface of the titanium alloy screw is oxidized into an oxide film under the action of electrolysis, and is removed by the metal bond grinding wheel 8, exposing a new surface, and continues to be electrolyzed;

[0049] Step 4: turn off the programmable pulse power supply I5, stop electrolyzing the titanium alloy screw, and stop the positive micro-feeding of the metal bond grinding wheel 8 in the Y-axis direction; polish the titanium alloy screw with the oxide film on the surface of the metal bond grinding wheel 8, and the polishing time is 10 min;

[0050] Step 5. Turn off the programmable pulse power supply II10, stop the cyclic feeding of the titanium alloy screw in the X-axis direction, withdraw the metal bond grinding wheel 8, and stop the rotation of the titanium alloy screw and the brush 1; loosen the headstock 2 and the tailstock 3, and remove the titanium alloy screw.

[0051] In the embodiment, the electrolyte composition includes: 8wt.% sodium nitrate, 3wt.% sodium molybdate, 3wt.% sodium silicate, 2wt.% propylene glycol, 2wt.% sodium chloride, and the balance is deionized water. The electrolyte can be used for online electrolysis of the metal bond grinding wheel 8, and can have good film-forming performance during the workpiece electrolysis process, has good electrical conductivity and cooling performance, and has good passivation and rust prevention performance, and can take away the grinding chips to prevent channel clogging.

[0052] In the embodiment, a 3000# metal bond CBN forming grinding wheel is used to perform double electrolytic grinding on the titanium alloy screw, and the gap between the copper electrode 9 and the metal bond grinding wheel 8 is adjusted to 0.05 mm. The entire grinding process includes 15 min pre-sharpening, 25 min dynamic grinding, 10 min polishing, and the flow rate of the electrolyte is 20 L / min. The relevant parameters of the titanium alloy screw used are shown in Table 1, the processing parameters are shown in Table 2, and the electrolytic parameters are shown in Table 3.

[0053] Table 1:

[0054] Material shape Diameter (mm) Aspect Ratio Pitch (mm) Original roughness (μm) Ti-6Al-4V rectangle 20 10 8 0.5

[0055] Table 2:

[0056] Grinding wheel specifications 3000# Bronze Bond CBN Forming Grinding Wheel Abrasive Concentration 175% Grinding wheel speed 1500r / min Workpiece speed 50 r / min Brush speed 200 r / min Metal bond grinding wheel feed 2μm / min

[0057] Table 3:

[0058] power supply Programmable pulse power supply Ⅰ Programmable pulse power supply Ⅱ Voltage 15 V 60 V Current density <![CDATA[0.1 A / cm 2 ]]> <![CDATA[0.3 A / cm 2 ]]> Duty Cycle 0.5 0.6

[0059] After double electrolytic grinding, the roughness of the spiral groove of the titanium alloy screw drops to below Ra50 nm, with a mirror effect.

[0060] It should be pointed out that the grinding device of the present invention is developed to meet the grinding needs of titanium alloy screws, but is not limited to processing titanium alloy screws, and can also be used for grinding screws of other materials.

[0061] The above general description of the invention involved in this application and the description of its specific implementation methods should not be understood as limiting the technical solutions of the invention. Based on the disclosure of this application, those skilled in the art can, without violating the constituent elements of the invention involved, add, reduce or combine the disclosed technical features in the above general description or / and specific implementation methods (including examples) to form other technical solutions within the scope of protection of this application.

Claims

1. A brush cathode assisted double electrolytic grinding device suitable for titanium alloy screws, characterized by: It includes a workpiece electrolysis module, a grinding wheel online electrolysis dressing module and an electrolyte module; The workpiece electrolysis module comprises a brush (1), a headstock (2), a tailstock (3), an X-axis bed slide (4) and a programmable pulse power supply I (5); the headstock (2) and the tailstock (3) are correspondingly arranged on the X-axis bed slide (4) which can move laterally to form a workpiece clamping drive device, and the workpiece clamping drive device is used to install a screw workpiece and can drive the screw workpiece to rotate; a brush seat (14) is arranged above the X-axis bed slide (4), and the brush (1) is installed on the brush seat (14) and can be driven to rotate by a power element correspondingly arranged on the brush seat (14); the brush (1) comprises a base body and bristles arranged on the base body; after the screw workpiece is installed on the workpiece clamping drive device, the bristles of the brush (1) can contact the screw workpiece; the base body of the brush (1) is electrically connected to the negative pole of the programmable pulse power supply I (5), and the positive pole of the programmable pulse power supply I (5) is used to electrically connect to the screw workpiece; The grinding wheel online electrolytic dressing module comprises a Z-axis column slide (7), a metal bond grinding wheel (8), a copper electrode (9) and a programmable pulse power supply II (10); a grinding wheel driving device is provided on the Z-axis column slide (7), and the metal bond grinding wheel (8) is installed on the grinding wheel driving device; The metal bond grinding wheel (8) can be lowered along with the Z-axis column slide (7) to fit with the surface of the screw workpiece and contact with the bristles of the brush (1); the Z-axis column slide (7) is arranged on the Y-axis feed slide (6); the copper electrode (9) is correspondingly arranged on the side of the metal bond grinding wheel (8), and there is a gap between the copper electrode (9) and the metal bond grinding wheel (8); the copper electrode (9) is electrically connected to the negative pole of the programmable pulse power supply II (10), and the metal bond grinding wheel (8) is electrically connected to the positive pole of the programmable pulse power supply II (10); The electrolyte module comprises a water tank (11) for storing electrolyte, and the water tank (11) is provided with a liquid supply pump I (12) and a liquid supply pump II (13). The liquid supply pump I (12) can transport the electrolyte to the contact position between the brush (1) and the screw workpiece through a pipeline, and the liquid supply pump II (13) can transport the electrolyte to the gap between the copper electrode (9) and the metal bond grinding wheel (8) through the pipeline.

2. The brush cathode assisted double electrolytic grinding device suitable for titanium alloy screw according to claim 1, characterized in that: The base of the brush (1) is a disc body made of an iron-based material, and the bristles are densely distributed on the cylindrical surface of the base body. The bristles are pig bristles, the length of the bristles is 5-35 mm, and the density of the bristles is 200-500 pieces / cm².

3. The brush cathode assisted double electrolytic grinding device suitable for titanium alloy screw according to claim 1, characterized in that: The gap between the copper electrode (9) and the metal bond grinding wheel (8) is 0.02-0.1 mm.

4. The brush cathode assisted double electrolytic grinding device suitable for titanium alloy screw according to claim 1, characterized in that: The copper electrode (9) is provided with a liquid supply hole (901), and the liquid supply pump II (13) is connected to the liquid supply hole (901) via a pipeline.

5. The brush cathode assisted double electrolytic grinding device suitable for titanium alloy screw according to claim 1, characterized in that: The water tank (11) is connected to the electrolyte recovery tank (16) via a reflux pipeline, and the X-axis bed slide (4) is arranged in the electrolyte recovery tank (16).

6. The brush cathode assisted double electrolytic grinding device suitable for titanium alloy screw according to claim 5, characterized in that: The reflux pipeline is provided with a filtering device.

7. A brush cathode assisted double electrolytic grinding method for titanium alloy screws, characterized in that: The method uses the brush cathode assisted double electrolytic grinding device of claim 1 to perform grinding, and the steps are as follows: Step 1: fix one end of the titanium alloy screw in the headstock (2), and install the other end in the tailstock (3); adjust the position of the metal bond grinding wheel (8) to fit the titanium alloy screw; Step 2: Start the liquid supply pump II (13) to fill the gap between the metal bond grinding wheel (8) and the copper electrode (9) with electrolyte; control the metal bond grinding wheel (8) to start rotating, turn on and adjust the relevant parameters of the programmable pulse power supply II (10) to the set values, perform pre-sharpening, and form an oxide film; Step 3: Control the brush (1) to rotate, start the liquid supply pump I (12) to fill the space between the titanium alloy screw and the base of the brush (1) with electrolyte; the titanium alloy screw rotates under the drive of the workpiece clamping drive device, and turn on and adjust the relevant parameters of the programmable pulse power supply I (5) to the set values; the titanium alloy screw is cyclically fed through the X-axis bed slide (4), and the metal bond grinding wheel (8) is positively micro-fed through the Y-axis feed slide (6); during the grinding process, the surface material of the metal bond grinding wheel (8) is ionized and dissolved, so that The abrasive grains protrude and an oxide film is generated on the surface of the metal bond grinding wheel (8). As grinding proceeds, the oxide film is removed under the mechanical action of the titanium alloy screw, making the passivated abrasive grains easy to fall off, exposing new abrasive grains inside, so that the surface of the metal bond grinding wheel (8) always has sharp abrasive grains, thereby realizing the online dressing of the metal bond grinding wheel (8); at the same time, the surface of the titanium alloy screw is oxidized into an oxide film under the action of electrolysis, and is removed by the metal bond grinding wheel (8), exposing a new surface, which continues to be electrolyzed; Step 4: After the processing of step 3 reaches the set time, the programmable pulse power supply I (5) is turned off, the electrolytic titanium alloy screw is stopped, and the metal bond grinding wheel (8) stops the positive micro-feed in the Y-axis direction; the titanium alloy screw is polished with the oxide film on the surface of the metal bond grinding wheel (8); After the processing of step 5 and step 4 reaches the set time, turn off the programmable pulse power supply II (10), stop the cyclic feeding of the titanium alloy screw in the X-axis direction, withdraw the metal bond grinding wheel (8), and stop the rotation of the titanium alloy screw and the brush (1); loosen the headstock (2) and the tailstock (3), and remove the titanium alloy screw.

8. The brush cathode assisted double electrolytic grinding method of a titanium alloy screw as claimed in claim 7, characterized in that: The electrolyte composition includes: 5-10wt.% sodium nitrate, 2-5wt.% sodium molybdate, 2-5wt.% sodium silicate, 1-3wt.% propylene glycol, 1-2wt.% sodium chloride, and the balance is deionized water.

9. The brush cathode assisted double electrolytic grinding method of a titanium alloy screw as claimed in claim 7, characterized in that: The relevant parameters of the programmable pulse power supply II (10) include output voltage, duty cycle and internal resistance; in step 2, the output voltage is set to 45-90 V, the duty cycle is set to 0.5-0.8, and the internal resistance is set to 5-300 Ω.

10. The brush cathode assisted double electrolytic grinding method of a titanium alloy screw as claimed in claim 7, characterized in that: The relevant parameters of the programmable pulse power supply I (5) include output voltage, duty cycle and internal resistance; in step three, the output voltage is set to 10-30 V, the duty cycle is set to 0.5-0.8, and the internal resistance is set to 5-300 Ω.

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