Machining method for improving anodizing appearance quality consistency of aluminum alloy special-shaped part

Abstract

The invention discloses a machining method for improving anodizing appearance quality consistency of an aluminum alloy special-shaped part. The machining method comprises the three steps of mechanical roll finish, chemical polishing and anodizing. The appearance consistency of the sample piece and the aluminum alloy special-shaped part obtained through treatment is good.

Description

Technical Field

[0001] The invention relates to a processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts, and belongs to the technical field of aluminum alloy appearance processing. Background Art

[0002] When flying in an ocean environment, aircraft will be corroded by marine atmosphere, alternating dry and wet conditions, and salt deposition. Therefore, aluminum alloy parts on the aircraft must have corrosion resistance and other properties.

[0003] Adding a film layer on the surface of aluminum alloy parts can effectively improve the surface wear resistance and corrosion resistance of aluminum alloy parts (see Chinese patent publication number CN108977865B). However, according to the existing surface treatment processing method, it is difficult to meet the requirements for the appearance consistency of the film layer prepared on the aluminum alloy parts. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts.

[0005] The present invention is achieved through the following technical solutions.

[0006] The invention provides a processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts, which comprises three steps of mechanical rolling, chemical polishing and anodizing.

[0007] The mechanical tumbling step is: placing the workpiece into the mechanical tumbling equipment for tumbling, adding tumbling abrasive into the drum, and subjecting the workpiece to a small amplitude and high frequency grinding and polishing of the abrasive in the tumbling drum to achieve uniform macroscopic structure of the substrate surface.

[0008] The chemical polishing step is: after preparing the chemical polishing liquid, chemically polishing the aluminum alloy workpiece to reduce the surface roughness of the part, adjust the electrochemical state of the workpiece surface to be uniform, and remove the tiny particles of abrasive grains and metal chips remaining on the workpiece surface during the mechanical rolling process.

[0009] The anodizing step is: using an acidic solution to continuously oxidize and dissolve the surface of the aluminum alloy material to generate a porous film layer.

[0010] The chemical polishing step is divided into the following steps: acceptance of incoming parts → putting on tooling → water washing → pre-polishing → water washing → chemical polishing → water washing → polishing → water washing → drying.

[0011] The chemical polishing steps are as follows: placing the workpiece in a polishing tank, and pouring in a chemical polishing liquid at a temperature of 80°C to 90°C for 0.5min to 3min, and washing with water at room temperature for 1min to 3min.

[0012] The chemical polishing liquid consists of 68-75% phosphoric acid (specific gravity 1.9), 3-5% nitric acid (68%), and 20-25% hydrogen peroxide (H2O2).

[0013] The beneficial effect of the present invention is that the film weight of the sample obtained by the present invention after being dissolved in CrO3 and phosphoric acid solution should be no less than 108 mg / dm 2 ; It can withstand a salt spray working environment of 35°C and a pH range of 6.5 to 7.2; at the same time, it can withstand 200 hours of ultraviolet light exposure, and the appearance consistency of aluminum alloy special-shaped parts is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Comparison of samples obtained by the prior art process and the process of the present invention Figure 1 ;

[0015] Figure 2 Comparison of samples obtained by the prior art process and the process of the present invention Figure 2 ;

[0016] Figure 3 Comparison of samples obtained by the prior art process and the process of the present invention Figure 3 ;

[0017] Figure 1 to Figure 3 In the figure: a is a sample obtained by the prior art process; b is a sample obtained by the process technology of the present invention. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described below, but the scope of protection claimed is not limited to the description.

[0019] The present invention discloses a processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts. The processing technology mainly consists of three parts: mechanical rolling, chemical polishing, and anodizing:

[0020] Mechanical tumbling steps. The aluminum alloy workpiece is mechanically tumbling to remove surface scratches, processing textures and other surface damage and defects. The workpiece is placed in the mechanical tumbling equipment for tumbling. Add tumbling abrasives to the drum, and let the workpiece be subjected to small-amplitude and high-frequency grinding and polishing by the abrasives in the tumbling drum. During the tumbling process, the abrasives have two forms of cutting and rolling effects on the workpiece surface, and the process is continuously cyclical. This processing method is not selective for a specific surface of the workpiece, so it has the effect of improving the overall uniformity of the workpiece surface macrostructure, removing scratches and other damage, and reducing the roughness of the workpiece surface, and finally achieving a uniform macrostructure on the substrate surface.

[0021] Chemical polishing step. After the chemical polishing liquid is prepared, the aluminum alloy workpiece is chemically polished to further reduce the surface roughness of the parts and adjust the electrochemical state of the workpiece surface to be uniform. The microstructure of the workpiece surface after mechanical rolling is relatively undulating, and there is a certain scratch morphology, which also leads to uneven electrochemical state. Chemical polishing includes a series of complex reaction processes, which are related to the uniformity of the material's organization, electrochemical state and the state of the corrosion polishing liquid. During the polishing process, some of the solution components form a mucous film on the surface of the workpiece, and some components have a thinning effect on the film layer. Therefore, the microscopic protrusions that are exposed first are first exposed to the corrosive components in the solution and dissolved. After the protrusions in the high-energy state are dissolved to a certain extent, they are passivated by the passivating components to stop the dissolution process and re-covered with a mucous film. This process is continuously carried out on different parts of the workpiece surface until the workpiece obtains a continuous and uniform microscopic surface, while removing tiny particles such as abrasive particles and metal chips remaining on the workpiece surface during the mechanical rolling process.

[0022] The process flow of chemical polishing steps: acceptance of incoming parts → tooling → water washing → pre-polishing → water washing → chemical polishing → water washing → polishing → water washing → blow drying.

[0023] Incoming parts acceptance: The workpieces that have passed mechanical tumbling should not have serious oxide scale. Hang the workpiece on the tooling and wash it with water. Put the workpiece into the light output tank and pour in the chemical polishing liquid, and keep it at room temperature for 5min to 20min. Wash it with water at room temperature for 1min to 3min. Put the workpiece into the polishing tank and pour in the chemical polishing liquid at a temperature of 80℃ to 90℃ for 0.5min to 3min. Wash it with water at room temperature for 1min to 3min. Blow dry at 40℃ to 55℃.

[0024] The chemical polishing liquid consists of 68-75% phosphoric acid (specific gravity 1.9), 3-5% nitric acid (68%), and 20-25% hydrogen peroxide (H2O2).

[0025] Anodizing step. This step will generate a continuous, uniform and dense anodized film on the prepared surface. The anodizing process uses the acidic solution to oxidize and dissolve the surface of the aluminum alloy material continuously to generate a porous film. The aluminum oxide film layer significantly improves the corrosion resistance and weather resistance of aluminum alloy parts through physical isolation and its excellent moisture resistance, thereby improving the service life and performance of the parts.

[0026] The samples obtained by the present invention are shown in Figure 1 to Figure 3 Special Figure 1 , Figure 3 As shown in , the aluminum alloy special-shaped parts of sample No. b processed by the present invention have good appearance consistency.

[0027] The anodized film of the sample obtained by the treatment of the present invention is dissolved in CrO3 and phosphoric acid solution, and the film weight calculated based on the sample area should be no less than 108 mg / dm 2 ;

[0028] At the same time, it meets the requirements of the neutral salt spray 336h test: the product should be able to withstand the salt spray environment of 35℃ and pH value range of 6.5-7.2 and work normally. The product is assessed according to HB / Z 233.

[0029] At the same time, it meets the requirements of the 200h light resistance test: the product should be able to withstand 200h of ultraviolet light exposure, and be tested in accordance with GB / T11189.1 Method C. The ΔE value compared with alternative samples from the same batch should not be greater than 3.

Claims

1. A processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts, characterized in that: include: The process is divided into three steps: mechanical tumbling, chemical polishing and anodizing.

2. The processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts according to claim 1, characterized in that: The mechanical tumbling step is: placing the workpiece into the mechanical tumbling equipment for tumbling, adding tumbling abrasive into the drum, and subjecting the workpiece to a small amplitude and high frequency grinding and polishing of the abrasive in the tumbling drum to achieve uniform macroscopic structure of the substrate surface.

3. The processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts according to claim 1, characterized in that: The chemical polishing step is: after preparing the chemical polishing liquid, chemically polishing the aluminum alloy workpiece to reduce the surface roughness of the part, adjust the electrochemical state of the workpiece surface to be uniform, and remove the tiny particles of abrasive grains and metal chips remaining on the workpiece surface during the mechanical rolling process.

4. The processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts according to claim 1, characterized in that: The anodizing step is: using an acidic solution to continuously oxidize and dissolve the surface of the aluminum alloy material to generate a porous film layer.

5. The processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts according to claim 2, characterized in that: The chemical polishing step is divided into the following steps: acceptance of incoming parts → putting on tooling → water washing → pre-polishing → water washing → chemical polishing → water washing → polishing → water washing → drying.

6. The processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts according to claim 5, characterized in that: The chemical polishing steps are as follows: placing the workpiece in a polishing tank, and pouring in a chemical polishing liquid at a temperature of 80°C to 90°C for 0.5min to 3min, and washing with water at room temperature for 1min to 3min.

7. The processing method for improving the consistency of anodized appearance quality of aluminum alloy special-shaped parts according to claim 6, characterized in that: The chemical polishing liquid consists of 68-75% phosphoric acid (specific gravity 1.9), 3-5% nitric acid (68%), and 20-25% hydrogen peroxide (H2O2).

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