An electrolytic grinding method for honeycomb materials based on the freezing point temperature difference characteristics of the medium

Abstract

The present invention discloses a method for electrolytic grinding of honeycomb materials based on the freezing point temperature difference characteristics of a medium. The method is as follows: fill the cell grids of the honeycomb material to be processed with a liquid medium, then place the honeycomb material to be processed in an environment with a temperature not higher than the freezing point of the liquid medium, and perform electrolytic grinding after the liquid medium filled in the honeycomb material has solidified; wherein, the freezing point temperature of the electrolyte is lower than the freezing point temperature of the liquid medium. The method of the present invention realizes the mechanical and electrochemical protection of the cell structure by filling the pores of the honeycomb material with a high freezing point medium and solidifying it, so that the cell will not be deformed or damaged due to a large grinding force, nor will over-corrosion occur in the cell due to stray current.

Description

Technical Field

[0001] The present invention relates to a method for electrolytic grinding of honeycomb materials, and in particular to a method for electrolytic grinding of honeycomb materials based on the freezing point temperature difference characteristics of a medium. Background Art

[0002] Honeycomb material is a kind of bionic material composed of multiple hexagonal cell structures. Among known materials, its strength-to-weight ratio and stiffness-to-weight ratio are the highest. Due to its advantages of high strength, light weight, not easy to deform, and good wear resistance, it is widely used in the fields of aviation, transportation, etc., especially in the processing and manufacturing of multiple components of aeroengines. Honeycomb materials in the aviation field are generally made of difficult-to-machine materials such as nickel-based alloys and chromium-based alloys, and the wall thickness of the cell of the honeycomb material is generally 0.1 - 0.2 mm. When processing such parts by traditional mechanical grinding means, it is not only difficult to ensure the shape accuracy of the cell and the processing dimensions, but also causes great wear to the cutting tool.

[0003] Electrolytic grinding is an advanced manufacturing technology method that combines electrochemical action and mechanical grinding action, and has great advantages in the processing of difficult-to-machine materials. However, during the electrolytic grinding process of honeycomb materials, there are still phenomena such as deformation of the honeycomb core caused by mechanical grinding force and corrosion inside the core caused by stray current. Summary of the Invention

[0004] Object of the Invention: Aiming at the problem that during the processing of honeycomb materials by electrolytic grinding in the prior art, deformation of the honeycomb core is easily caused by mechanical grinding force and corrosion inside the core is caused by stray current, the present invention provides a method for electrolytic grinding of honeycomb materials based on the freezing point temperature difference characteristics of a medium.

[0005] Technical Solution: The method for electrolytic grinding of honeycomb materials based on the freezing point temperature difference characteristics of a medium described in the present invention is as follows: Fill the cells of the honeycomb material to be processed with a liquid medium, then place the honeycomb material to be processed in an environment with a temperature not higher than the freezing point of the liquid medium, and perform electrolytic grinding after the liquid medium filled in the honeycomb material condenses; wherein, the freezing point temperature of the electrolyte is lower than the freezing point temperature of the liquid medium.

[0006] Among them, the processing system used in the method includes a closed processing area. The honeycomb material to be processed is placed on the bottom plate of the sealed processing area. A refrigeration device is provided outside the closed processing area, and a temperature sensor I is provided inside the closed processing area; liquid leakage holes are provided on the bottom plate; it also includes a grinding wheel electrode and a nozzle; the grinding wheel electrode is connected to the negative pole of an external power supply through a wire, and the honeycomb material to be processed is connected to the positive pole of the external power supply through a wire; the nozzle is connected to a cleaning liquid tank filled with electrolyte outside through a connecting pipe; a concentration meter and a temperature sensor II are provided in the cleaning liquid tank; the medium in the cell of the honeycomb material to be processed is in a liquid state when added, and the temperature inside the closed processing area is maintained below the freezing point temperature of the liquid medium through the refrigeration device, so that the medium in the cell of the honeycomb material 6 is in a solidified state.

[0007] Among them, it also includes a turbid liquid tank. The liquid inlet of the turbid liquid tank is communicated with the liquid leakage hole of the closed processing area through a pipeline, and the liquid outlet of the turbid liquid tank is connected to the cleaning liquid tank through a connecting pipeline, and a filter is provided on the connecting pipeline.

[0008] Among them, a cooling device is also provided outside the cleaning liquid tank.

[0009] Among them, during the electrolytic grinding process, the temperature of the electrolyte in the cleaning liquid tank is monitored through the temperature sensor II, and the temperature of the electrolyte is kept stable through the electrolyte cooling device (the electrolyte temperature is controlled within the temperature range that makes the filling medium in a condensed state).

[0010] Among them, it also includes a PLC control box. The refrigeration device, the cooling device, the temperature sensor I and the temperature sensor II are respectively connected to the PLC control box through cables.

[0011] Among them, the grinding wheel electrode is a conductive grinding wheel, and insulating abrasive grains are evenly attached to the surface of the grinding wheel electrode.

[0012] Among them, the electrolyte used in the method of the present invention is a sodium nitrate solution or a sodium chloride solution; the liquid filling medium is the basic component of the electrolyte, such as water, or other supplementary components that do not affect the electrochemical dissolution performance of the electrolyte, such as C6H 11 NaO7; the electrolyte in the method of the present invention can be recycled.

[0013] Among them, during the electrolytic grinding process, the temperature inside the closed processing area is -10 to 0 °C.

[0014] Among them, the change in the concentration of the electrolyte in the cleaning liquid tank is monitored through the concentration meter. When the deviation between the electrolyte concentration in the cleaning liquid tank and the initial electrolyte concentration is greater than 5‰, the electrolyte is replenished, and the replenishment amount of the electrolyte is calculated using the following formula:

[0015] b = n×(v0 + v1×μ) - m

[0016] Among them, b is the mass of the electrolyte, n is the initial concentration of the electrolyte solution, v0 is the volume of the electrolyte solution, v1 is the volume of the processed part of the honeycomb material, m is the initial mass of the electrolyte, and μ is the porosity of the honeycomb material.

[0017] The present invention utilizes the different freezing point temperatures of the filling medium and the electrolyte solution; the honeycomb pores of the honeycomb material are filled with the filling medium and fixed on the workbench in the sealed processing area. By means of an external refrigeration device, the temperature in the sealed processing area is controlled between the freezing point temperature of the electrolyte solution and the freezing point temperature of the filling medium. At this time, the filling medium condenses into a solid state, achieving the effect of enhancing the rigidity of the honeycomb material, which can meet the processing process with greater grinding force, while the electrolyte solution can be in a non-condensed liquid state at this temperature, ensuring the smooth implementation of the electrolytic grinding composite processing process; the filling medium in the honeycomb pores can also effectively protect the non-processing areas in the honeycomb pores, thereby preventing the occurrence of the phenomenon of internal corrosion of the cell due to stray current.

[0018] During the processing, the nozzle sprays the electrolyte solution towards the processing area; the grinding wheel electrode gradually cuts into the honeycomb material along a predetermined path. The abrasive grains on the surface of the grinding wheel break the solid filling medium on the surface of the honeycomb material through mechanical force, and then local electrochemical dissolution occurs in this area; as the grinding wheel electrode continues to feed, the filling medium in the honeycomb pores of the honeycomb material is removed layer by layer, and the exposed honeycomb material is removed by electrolytic grinding, while the unexposed honeycomb material is effectively protected.

[0019] Beneficial effects: By filling the pores of the honeycomb material with a high-freezing-point medium and making it condense and solidify, the present invention realizes the mechanical and electrochemical protection of the cell structure, so that the cell will not be deformed or damaged due to greater grinding force, nor will it cause over-corrosion in the cell due to stray current; with the auxiliary effect of the filling medium, the present invention does not need to strictly control the matching relationship between the mechanical grinding effect and the electrochemical effect, thereby reducing the processing difficulty of the honeycomb material; the present invention fills the honeycomb pores with a high-freezing-point medium and carries out electrolytic grinding processing with a low-freezing-point medium to achieve high-quality processing of the honeycomb material. Description of the Drawings

[0020] Figure 1 It is the system schematic diagram of the processing system adopted by the electrolytic grinding processing method of the present invention;

[0021] Figure 2 It is the structural schematic diagram of the honeycomb material to be processed before filling the medium;

[0022] Figure 3 It is the structural schematic diagram of the honeycomb material to be processed after filling the medium.

[0023] Figure 4 It is the product effect diagram of the conventional electrolytic grinding processing;

[0024] Figure 5 It is the product processing effect diagram of the technical method of the present invention. Specific embodiments

[0025] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0026] As Figures 1 to 3 , the processing system used in the processing method of the present invention includes a sealed processing area 1. The honeycomb material 6 to be processed is placed on the workbench 5 in the sealed processing area 1. A refrigeration device is provided outside the sealed processing area 1, and a temperature sensor I is provided inside the sealed processing area 1; there is a liquid leakage hole 7 on the workbench 5; the processing system also includes a grinding wheel electrode 3 and a nozzle 2 (the position and incident angle of the nozzle are adjusted before processing, and the nozzle does not need to move during the processing); the grinding wheel electrode 3 is connected to the negative pole of an external power supply 4 through a wire, and the honeycomb material 6 to be processed is connected to the positive pole of the external power supply 4 through a wire. The grinding wheel electrode 3 is a conductive grinding wheel, and insulating abrasive grains are evenly attached to the surface of the grinding wheel electrode 3; the nozzle 2 is connected to a cleaning liquid tank 12 filled with electrolyte outside through a connecting pipe; a concentration meter 11 and a temperature sensor II 14 are provided in the cleaning liquid tank 12; the medium in the cell of the honeycomb material 6 to be processed is in a liquid state when added. The temperature in the sealed processing area 1 is maintained below the freezing point temperature of the liquid medium through the refrigeration device, so that the medium in the cell of the honeycomb material 6 to be processed is in a solidified state. During the electrolytic grinding process, the temperature in the sealed processing area 1 is -10 to 0 °C.

[0027] The processing system also includes a turbid liquid tank 13. The liquid inlet of the turbid liquid tank 13 is communicated with the liquid leakage hole 7 in the sealed processing area 1 through a pipeline, and the liquid outlet of the turbid liquid tank 13 is connected to the cleaning liquid tank 12 through a connecting pipeline. A filter 10 is provided on the connecting pipeline. A cooling device is also provided outside the cleaning liquid tank 12. During the electrolytic grinding process, the temperature of the electrolyte in the cleaning liquid tank 12 is monitored through the temperature sensor II 14, and the temperature of the electrolyte is kept stable through the cooling device.

[0028] The processing system also includes a PLC control box. The refrigeration device, the cooling device, the temperature sensor I and the temperature sensor II 14 are respectively connected to the PLC control box through cables; the PLC control box monitors the temperature of the corresponding area through the temperature sensor, and regulates the temperature of the corresponding area through the refrigeration device to keep the temperature of the corresponding area at the required temperature.

[0029] Among them, the electrolyte used in the method of the present invention is a sodium nitrate solution or a sodium chloride solution; the liquid filling medium is a basic component of the electrolyte, such as water, or other supplementary components that do not affect the electrochemical dissolution performance of the electrolyte, such as C6H 11 NaO7; the electrolyte in the method of the present invention can be recycled.

[0030] Among them, the concentration change of the electrolyte in the clear liquid tank 12 is monitored by a concentration meter 11. When the deviation between the electrolyte concentration in the clear liquid tank 12 and the initial electrolyte concentration is greater than 5‰, the electrolyte is replenished. The replenishment amount of the electrolyte is calculated by the following formula:

[0031] b = n×(v0 + v1×μ) - m

[0032] Among them, b is the mass of the electrolyte, n is the initial electrolyte concentration, v0 is the volume of the electrolyte, v1 is the volume of the processed part of the honeycomb material, m is the initial mass of the electrolyte, and μ is the porosity of the honeycomb material.

[0033] The electrolytic grinding processing method of the honeycomb material of the present invention specifically includes the following steps:

[0034] (1) Fill an appropriate amount of liquid filling medium into the pore cells of the honeycomb material to be processed. In this embodiment, the liquid filling medium is water. Place the honeycomb material filled with water (the honeycomb material filled with water is placed in a container and put into a low-temperature environment) into a low-temperature environment to cause the water in the pore cells of the honeycomb material to freeze into ice. In this case, the low-temperature environment is -5°C;

[0035] (2) Position and clamp the honeycomb material after ice sealing on the workbench in the sealed processing area. Start the refrigeration device outside the sealed processing area to make the temperature in the sealed processing area not higher than 0°C. Connect the honeycomb material to the positive pole of the power supply, select a suitable grinding wheel electrode, and connect the grinding wheel electrode to the negative pole of the power supply; Place the nozzle on one side of the feeding direction of the grinding wheel to ensure that the electrolyte can be evenly sprayed onto the working area; Check the electrolyte circulation system to ensure that there is no leakage in the circuit system, and check the circuit to ensure no short circuit or open circuit;

[0036] (3) Turn on the electrolyte circulation system to make the grinding wheel electrode approach the processing surface of the honeycomb material; Turn on the power supply to apply a certain potential difference between the grinding wheel electrode and the honeycomb material, and make the grinding wheel electrode cut into the honeycomb material at a constant speed; In this embodiment, the electrolyte is a sodium nitrate solution with a concentration of 10%. The grinding wheel electrode removes the ice layer on the surface of the honeycomb material to be processed, and the electrochemical action removes the exposed honeycomb material and a small amount of burrs generated by grinding. The processing products are discharged from the leakage hole out of the sealed processing area with the electrolyte; The concentration meter continuously detects the concentration of the electrolyte in the clear liquid tank and replenishes the electrolyte at any time to keep the electrolyte concentration stable;

[0037] (4) After processing, turn off the power supply and the electrolyte circulation system, remove the workpiece, put it into the room temperature environment, melt the residual solidified condensate in the pore cells, and use ultrasonic cleaning to clean the honeycomb pores and the processing residues on the surface.

[0038] Figures 4 to 5 It is a comparison of the processing samples of the processing effects of the conventional electrolytic grinding processing method and the processing effects of the technical method of the present invention. AsFigure 4 It can be seen that in some areas of the sample (such as the single-wall area with a smaller honeycomb cell wall thickness), due to a large amount of stray current penetrating the side walls of the honeycomb cells, over-corrosion leads to wall thickness depressions, while in other areas (such as the double-wall area with a larger honeycomb cell wall thickness), burrs are generated due to greater grinding force. Figure 5 This is a processed sample of the processing effect of the technical method of the present invention, such as Figure 5 It can be seen that the end faces of the honeycomb cells of the sample are uniform, and there is almost no over-corrosion and burr phenomenon.

Claims

1. A method for electrolytic grinding of honeycomb materials based on the freezing point temperature difference characteristics of the medium, characterized in that: The method is as follows: Fill the pores of the honeycomb material to be processed with a liquid medium, then place the honeycomb material to be processed in an environment with a temperature not higher than the freezing point of the liquid medium, and perform electrolytic grinding after the liquid medium filled in the honeycomb material solidifies; wherein, the freezing point temperature of the electrolyte is lower than the freezing point temperature of the liquid medium. The processing system used in the method includes a closed processing area. The honeycomb material to be processed is placed on the bottom plate of the sealed processing area. A refrigeration device is provided outside the closed processing area, and a temperature sensor I is provided inside the closed processing area. During the electrolytic grinding process, the temperature inside the closed processing area is -10 to 0 °C; there are liquid leakage holes on the bottom plate; it also includes a grinding wheel electrode and a nozzle; the grinding wheel electrode is connected to the negative pole of an external power supply through a wire, and the honeycomb material to be processed is connected to the positive pole of the external power supply through a wire; the nozzle is connected to a clean liquid tank filled with electrolyte outside through a connecting pipe; a concentration meter and a temperature sensor II are provided in the clean liquid tank; the medium in the pores of the honeycomb material to be processed is in a liquid state when added, and the temperature inside the closed processing area is maintained below the freezing point temperature of the liquid medium through the refrigeration device, so that the medium in the pores of the honeycomb material to be processed is in a solidified state; the electrolyte is a sodium nitrate solution or a sodium chloride solution with a concentration of 10%; the liquid medium is water. Monitor the change in the concentration of the electrolyte in the clean liquid tank through the concentration meter. When the deviation between the electrolyte concentration in the clean liquid tank and the initial electrolyte concentration is greater than 5‰, supplement the electrolyte, and the supplement amount of the electrolyte is calculated using the following formula: ； where b is the mass of the electrolyte, n is the initial concentration of the electrolyte solution, is the volume of the electrolyte solution, is the volume of the processed part of the honeycomb material, is the initial mass of the electrolyte, is the porosity of the honeycomb material.

2. The electrolytic grinding method for honeycomb materials based on the freezing point temperature difference characteristics of the medium according to claim 1, characterized in that: The processing system also includes a turbid liquid tank. The liquid inlet of the turbid liquid tank is communicated with the liquid leakage hole of the closed processing area through a pipeline, and the liquid outlet of the turbid liquid tank is connected to the clean liquid tank through a connecting pipeline, and a filter is provided on the connecting pipeline.

3. The electrolytic grinding method for honeycomb materials based on the freezing point temperature difference characteristics of the medium according to claim 1, characterized in that: A cooling device is also provided outside the clean liquid tank.

4. The electrolytic grinding method for honeycomb materials based on the freezing point temperature difference characteristics of the medium according to claim 1, characterized in that: During the electrolytic grinding process, monitor the temperature of the electrolyte in the clean liquid tank through the temperature sensor II, and keep the temperature of the electrolyte stable through the electrolyte cooling device.

5. The electrolytic grinding method for honeycomb materials based on the freezing point temperature difference characteristics of the medium according to claim 1, characterized in that: The processing system also includes a PLC control box. The refrigeration device, the cooling device, the temperature sensor I, and the temperature sensor II are respectively connected to the PLC control box through cables.

6. The electrolytic grinding method for honeycomb materials based on the freezing point temperature difference characteristics of the medium according to claim 1, characterized in that: The grinding wheel electrode is a conductive grinding wheel, and insulating abrasive grains are evenly attached to the surface of the grinding wheel electrode.

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