Brush cathode assisted double electrolytic grinding device and method suitable for titanium alloy screw

Abstract

The present invention discloses a brush cathode assisted dual electrolytic grinding device and method suitable for titanium alloy screws. The brush cathode assisted dual electrolytic grinding device includes a workpiece electrolysis module, a grinding wheel online electrolytic dressing module and an electrolyte module. The present invention uses the screw workpiece and the metal bond grinding wheel as electrolysis objects at the same time, which not only realizes the online electrolytic dressing processing of the grinding wheel, but also realizes the electrolytic grinding processing of the workpiece, thereby achieving high-precision surface quality and high grinding efficiency; and because metal removal mainly relies on electrochemical action, and the mechanical action mainly removes the anodized 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 dual electrolytic grinding process, which also reduces the adhesive wear of the grinding wheel and improves the surface finish of the workpiece.

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 typically difficult-to-machine material. Its low thermal conductivity and tendency to stick to the tool easily result in poor surface finish during machining. Furthermore, the large aspect ratio, poor rigidity, and complex shape of the screw make titanium alloy screw machining particularly challenging.

[0003] Titanium alloy screws are generally formed by milling or turning. The surface quality of the processed parts is poor and cannot meet the performance requirements of the machine. Grinding is required to improve the surface quality. Titanium alloy screws are generally ground with metal bond grinding wheels. Currently, the main problem faced by titanium alloy screw grinding is that under the combined action of large grinding forces and high grinding temperatures, the workpiece material will be transferred to the grinding wheel surface, resulting in severe adhesion of the metal bond grinding wheel abrasive grains and deterioration of the screw surface quality. 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 uses the screw workpiece and the metal bond grinding wheel as electrolysis objects at the same time, thereby realizing online electrolytic dressing of the grinding wheel so that the grinding wheel surface always has sharp abrasive grains, and realizing electrolytic grinding of the workpiece, generating an easily removable oxide film on the workpiece surface, thereby achieving high-precision surface quality and high grinding efficiency; and since 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 carry 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 adhesive 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, comprising a workpiece electrolysis module, a grinding wheel online electrolytic dressing module and an electrolyte module; the workpiece electrolysis 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 to 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 drive device, and the metal bond grinding wheel is installed on the grinding wheel drive 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 of 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 the workpiece electrolysis module and the grinding wheel online electrolytic dressing module, both the online electrolytic dressing of the grinding wheel and the electrolytic grinding 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, which can achieve high-precision surface quality and high grinding efficiency.

[0009] (2) The material removal of the titanium alloy screw mainly relies on electrochemical action, and the mechanical action is mainly to remove the anodic oxide 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 adhered to the abrasive grains of the grinding wheel, further reducing the adhesive wear of the grinding wheel, and preventing the grinding chips from adhering to the abrasive grains of the grinding wheel and making 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 brush base is a disc made of iron-based material, with bristles densely distributed on the cylindrical surface of the base. The bristles are pig bristles, with a length of 5-35 mm and a density of 200-500 bristles / cm². Using pig bristles as the bristles of the brush can make the brush have good elasticity and cushioning properties.

[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 machining, 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 an electrolyte recovery tank via a return line, and the X-axis bed slide is located in the electrolyte recovery tank. Furthermore, a filter device is provided on the return line. During processing, the electrolyte falls into the electrolyte recovery tank and then flows back to the water tank, achieving recycling.

[0016] Furthermore, the brush base is arranged on a brush adjustment guide rail, thereby enabling the position of the brush to 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 is provided. The method utilizes 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 so that the electrolyte is filled between the titanium alloy screw and the base of the brush; 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, realizing online dressing of the metal bond grinding wheel; 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, the programmable pulse power supply I is turned off, the electrolytic titanium alloy screw is stopped, and the metal bond grinding wheel 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;

[0023] Step 5. After the processing of step 4 reaches the set value, turn off the programmable pulse power supply II, stop the X-axis cyclic feeding of the titanium alloy screw, 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 the surface quality of the titanium alloy screw after processing is good.

[0025] Furthermore, the electrolyte comprises 5-10 wt.% sodium nitrate, 2-5 wt.% sodium molybdate, 2-5 wt.% sodium silicate, 1-3 wt.% glycerol, 1-2 wt.% sodium chloride, and the balance deionized water. This electrolyte can be used for online electrolysis of metal-bonded grinding wheels and exhibits excellent film formation during the workpiece electrolysis process. It also exhibits excellent electrical conductivity and cooling properties, as well as good passivation and rust prevention properties, and can remove grinding debris 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 This is a schematic structural 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 the online electrolytic dressing module of the 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 will be further described below with reference to the accompanying drawings and embodiments, but they are not intended to limit the present invention. Any content not described in detail below or any structure not shown in the accompanying drawings is common knowledge in the art.

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

[0034] A brush cathode-assisted double electrolytic grinding device suitable for titanium alloy screws includes a workpiece electrolysis module, a grinding wheel online electrolytic dressing module and an electrolyte module; during processing, the workpiece electrolysis 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 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 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 provided 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 drive device, and the metal bond grinding wheel 8 is installed on the grinding wheel drive device; the metal bond grinding wheel 8 can be lowered with the Z-axis column slide 7 to fit the surface of the screw workpiece and contact 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 I 12 and a liquid supply pump II 13. The liquid supply pump I 12 can transport the electrolyte through a pipeline to the contact part between the brush 1 and the screw workpiece, and the liquid supply pump II 13 can transport the electrolyte through a pipeline to the gap between the copper electrode 9 and the metal bond grinding wheel 8.

[0038] In this embodiment, the brush 1 comprises a disc-shaped body made of an iron-based material. The bristles are densely distributed on the cylindrical surface of the base. The bristles are 20 mm long and have a density of 400 bristles / cm². Using bristles as the bristles of the brush 1 provides excellent elasticity and cushioning properties, and also absorbs and disperses 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 this embodiment, the water tank 11 is connected to an electrolyte recovery tank 16 via a return line. The X-axis bed slide 4 is located in the electrolyte recovery tank 16. A filter device is provided on the return line. The electrolyte recovery tank 16 and the return line work together to transport used electrolyte back to the water tank 11, achieving electrolyte recycling and saving processing costs.

[0042] In the embodiment, the metal-bonded grinding wheel is provided with a grinding wheel cover (not shown in the accompanying drawings to clearly illustrate the copper electrode 9). The copper electrode 9 is mounted on the grinding wheel cover, which 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 provided on a brush adjustment guide rail 17 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 guide 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, a titanium alloy screw is ground. In this embodiment, a brush cathode assisted double electrolytic grinding method for a titanium alloy screw is performed as follows:

[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 output voltage 60 V, duty cycle 0.6, and internal resistance 200 Ω, perform pre-sharpening for 15 minutes, 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 rotates under the drive of the workpiece clamping drive device 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 to perform a back and forth feed motion to achieve repeated grinding of the entire spiral groove of the titanium alloy screw, and the metal bond grinding wheel 8 is positively micro-fed through the Y-axis feed slide 6 at a feed rate of 2 μm / min, and the dynamic grinding time is 25 min; During the grinding process, the surface material 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 it easy for the passivated abrasive grains 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, which 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-feed 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 minutes;

[0050] Step 5: Turn off the programmable pulse power supply II10, stop the X-axis cyclic feeding of the titanium alloy screw, 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: 8 wt.% sodium nitrate, 3 wt.% sodium molybdate, 3 wt.% sodium silicate, 2 wt.% glycerol, 2 wt.% sodium chloride, and the balance is deionized water. This electrolyte can be used for online electrolysis of the metal-bonded grinding wheel 8 and exhibits excellent film formation during the workpiece electrolysis process. It also has excellent conductivity and cooling properties, as well as good passivation and rust prevention properties, and can remove grinding debris and prevent channel clogging.

[0052] In this example, a titanium alloy screw was subjected to dual electrolytic grinding using a 3000# metal-bonded CBN forming grinding wheel. The gap between the copper electrode 9 and the metal-bonded grinding wheel 8 was adjusted to 0.05 mm. The entire grinding process included 15 minutes of pre-sharpening, 25 minutes of dynamic grinding, and 10 minutes of polishing. The electrolyte flow rate was 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 and the description of its specific embodiments involved in this application should not be construed as limiting the technical solutions of the invention. Based on the disclosure of this application, those skilled in the art may, without violating the constituent elements of the invention involved, add to, subtract from, or combine the disclosed technical features in the above general description and / or specific embodiments (including examples) to form other technical solutions within the scope of protection of this application.

Claims

1. Brush cathode assisted double electrolytic grinding device suitable for titanium alloy screws, characterized by: Including workpiece electrolysis module, grinding wheel online electrolysis dressing module and electrolyte module; 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 I (5); the headstock (2) and the tailstock (3) are correspondingly arranged on the X-axis bed slide (4) that 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 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 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 the surface of the screw workpiece and contact 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 includes 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 portion 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 a 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 made of an iron-based material, and 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.

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: A filtering device is provided on the return pipeline.

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 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, turn on and adjust the relevant parameters of the programmable pulse power supply I (5) to the set value; the titanium alloy screw is cyclically fed through the X-axis bed slide (4), and the metal bond grinding wheel (8) is positively fed in a small amount 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 are protruded, and 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, so that the passivated abrasive grains are easily detached, exposing new abrasive grains inside, thereby ensuring 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; After the processing of step 4 and 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 for a titanium alloy screw according to claim 7, characterized in that: The electrolyte composition includes: 5-10wt.% sodium nitrate, 2-5wt.% sodium molybdate, 2-5wt.% sodium silicate, 1-3wt.% glycerol, 1-2wt.% sodium chloride, and the balance is deionized water.

9. The brush cathode assisted double electrolytic grinding method for a titanium alloy screw according to 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 for a titanium alloy screw according to 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 3, 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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