CN112475784A

CN112475784A - Processing method for removing black ash on surface of die-casting aluminum alloy, die-casting aluminum alloy and mobile phone shell

Info

Publication number: CN112475784A
Application number: CN202011131011.5A
Authority: CN
Inventors: 朱义岑; 黄华强; 肖伟龙
Original assignee: Guangdong Evenwin Precision Technology Co Ltd
Current assignee: Guangdong Evenwin Precision Technology Co Ltd
Priority date: 2020-10-21
Filing date: 2020-10-21
Publication date: 2021-03-12
Anticipated expiration: 2040-10-21
Also published as: CN112475784B

Abstract

The invention relates to the technical field of metal surface treatment, in particular to a novel treatment method for removing black ash on the surface of die-casting aluminum alloy, which comprises the steps of firstly cleaning the die-casting aluminum alloy obtained by die-casting molding, then carrying out TRI treatment and CNC machining; and performing sand blasting treatment on the surface of the die-casting aluminum alloy subjected to CNC machining, and finally performing anodic oxidation treatment on the die-casting aluminum alloy subjected to sand blasting treatment to obtain a die-casting aluminum alloy finished product. According to the invention, through the treatment mode, a sand surface protective layer can be formed on the surface of the die-casting aluminum alloy, the sand surface protective layer can isolate chemical reaction between silicon in the die-casting aluminum alloy material and alkali, and the corrosion of the surface of the die-casting aluminum alloy by acid and alkali can be prevented. The invention has simple process and good ash removal effect, does not need ash removal by adopting an ash remover, can greatly reduce the material cost, is environment-friendly and does not cause pollution to the environment.

Description

Processing method for removing black ash on surface of die-casting aluminum alloy, die-casting aluminum alloy and mobile phone shell

Technical Field

The invention relates to the technical field of metal surface treatment, in particular to a treatment method for removing black ash on the surface of die-casting aluminum alloy, the die-casting aluminum alloy and a mobile phone shell.

Background

The die-casting aluminum alloy has incomparable advantages of other machined parts, such as high dimensional precision, high production efficiency, excellent economic effect and the like, so that the die-casting aluminum alloy has wide application in industry. The processing steps of the traditional die-casting aluminum alloy comprise: firstly, punching to prepare a die-casting aluminum alloy base material, cleaning, then carrying out TRI treatment, then forming a die-casting aluminum alloy part through CNC processing, and finally obtaining a die-casting aluminum finished product meeting the appearance requirement through a specific anodic oxidation treatment process.

In the prior art, silicon element is generally added into die-casting aluminum alloy materials: silicon can improve the fluidity, tensile strength and hardness of the alloy, improve the castability of the alloy, reduce the shrinkage rate and hot cracking tendency, improve the wear resistance and the like. However, since silicon is easy to react with alkaline solution, a layer of black ash is formed on the surface of the die-casting aluminum alloy part after the alkaline reaction, which has a certain influence on the subsequent surface treatment process. Aiming at the problems, the prior process adopts a dust remover to remove black ash; however, the use of the dedusting agent has poor dedusting effect, high cost, environmental pollution and no pollution to the environment. In view of the above, a method for effectively removing black ash from die-cast aluminum, which is economical and environmentally friendly, is needed.

Disclosure of Invention

The invention provides a processing method for removing black ash on the surface of a die-casting aluminum alloy, which aims to solve the problems that the black ash on the surface of the existing die-casting aluminum alloy influences the subsequent process, and the ash is removed by adopting an ash remover, so that the cost is high and the environment is not protected.

In order to solve the problems existing in the invention, the invention provides a method for removing black ash from a die-casting aluminum alloy, which comprises the following steps:

1) cleaning the die-casting aluminum alloy obtained by die-casting molding;

2) carrying out TRI treatment on the cleaned die-casting aluminum alloy;

3) carrying out CNC machining on the die-casting aluminum alloy subjected to TRI treatment;

4) carrying out sand blasting treatment on the surface of the die-casting aluminum alloy processed by CNC, and forming a sand surface protective layer on the surface of the die-casting aluminum alloy subjected to sand blasting treatment;

5) and carrying out anodic oxidation treatment on the die-casting aluminum alloy subjected to sand blasting treatment to obtain a die-casting aluminum alloy finished product.

Preferably, in the step 2), the method further comprises the step of polishing the TRI-treated die-cast aluminum alloy.

Preferably, in the step 4), the die-casting aluminum alloy subjected to sand blasting treatment is subjected to fine polishing treatment.

Preferably, in step 4), the conditions of the blasting treatment are: the air pressure is 0.5 to 1.5kgf/cm²The running speed is 1.5-2.5 m/min.

Preferably, in step 4), the conditions of the blasting treatment are: the air pressure was 1.0kgf/cm²The running speed is 2.5 m/min.

Preferably, in step 4), the conditions of the blasting treatment are: the air pressure was 1.5kgf/cm²The running speed is 1.8 m/min.

Preferably, the sand used for the sand blasting treatment is zircon sand.

Preferably, in the step 4), the die-casting aluminum alloy after sand blasting is subjected to fine polishing treatment.

In order to solve the problems of the invention, the invention also provides a die-casting aluminum alloy obtained by the processing method for removing the black ash on the surface of the die-casting aluminum alloy.

In order to solve the problems existing in the invention, the invention also provides a mobile phone shell, which comprises a middle plate, wherein the middle plate is the die-casting aluminum alloy.

The invention has the beneficial effects that: the invention provides a processing method for removing black ash from the surface of a die-casting aluminum alloy, which is characterized in that the surface of the die-casting aluminum alloy is subjected to sand blasting treatment, the black ash on the surface of the die-casting aluminum alloy can be removed by utilizing high-speed sand blasting, and meanwhile, a sand surface protective layer is formed on the surface of the die-casting aluminum alloy, and can isolate the chemical reaction between silicon and alkali in the die-casting aluminum alloy material and prevent the surface of the die-casting aluminum alloy from being corroded by acid and alkali. The invention has simple process and good ash removal effect, does not need ash removal by adopting an ash remover, can greatly reduce the material cost, is environment-friendly and does not cause pollution to the environment.

Drawings

FIG. 1 is a flowchart of a treatment method for removing black ash from a surface of a die-cast aluminum alloy according to an embodiment of the present invention;

FIG. 2 is a graph showing the effect of ash removal in the adhesion test of example 1;

FIG. 3 is a graph showing the effect of ash removal in the adhesion test of example 2;

FIG. 4 is a graph showing the effect of ash removal in the adhesion test of example 3;

FIG. 5 is a graph showing the effect of the adhesion test of example 4 on ash removal.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terms "first", "second" and "third" in the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of the feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise. Furthermore, the terms "include" and "have," as well as any variations thereof, are intended to cover non-exclusive inclusions.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.

In the prior art, most of the metal materials used for the mobile phone casing, the middle plate and the frame are die-cast aluminum alloys with high silicon content of S33N. Wherein, adding silicon element into the die-casting aluminum alloy material: silicon can improve the castability of the alloy, improve the high-temperature fluidity of the alloy, reduce the shrinkage rate and the hot cracking tendency, improve the wear resistance and the like. In the process of anodizing the die-casting aluminum alloy, the aluminum alloy die-casting material contains silicon which is easy to react with alkaline solution, and silicon particles and black ash are formed on the surface of the die-casting aluminum alloy after the anodic oxidation treatment, so that a certain influence is generated on the subsequent treatment process. In the improved process, hole sealing treatment is tried to be carried out in some schemes, pores on the surface of the die-casting aluminum alloy are sealed, and acid and alkali cannot pass through the pores to have an erosion reaction with silicon; in some schemes, pre-oxidation is added after injection molding, so that an oxide film is formed on the surface of the die-casting aluminum alloy, and CNC cleaning and chemical corrosion reaction of an anode on the surface of the die-casting aluminum alloy are reduced. However, the problem of black and gray on the surface of the aluminum alloy die-casting still cannot be effectively solved by the scheme. The improvement point of the invention is that the surface of the die-casting aluminum alloy is subjected to sand blasting treatment, and a sand surface protective layer is formed on the surface of the die-casting aluminum alloy after the sand blasting treatment, and the sand surface protective layer can isolate silicon in the die-casting aluminum alloy material from generating chemical reaction with alkali.

More specifically, as shown in fig. 1, the invention discloses a treatment method for removing black ash from the surface of a die-casting aluminum alloy, which comprises the following steps:

1) cleaning, namely cleaning the die-casting aluminum alloy obtained by die-casting molding; in the step, the aluminum alloy liquid is cooled and formed in a die-casting die to obtain a die-casting aluminum alloy; in addition, the die-casting aluminum alloy can be processed into a shape by combining punching and polishing after die-casting molding, so that the appearance of the die-casting aluminum alloy is improved.

2) TRI treatment, namely performing TRI treatment on the cleaned die-casting aluminum alloy; the TRI treatment is to carry out special nanocrystallization treatment on the surface of the die-casting aluminum alloy to form a plurality of regular nanometer holes with specific shapes and certain sizes, form a layer of film in the nanometer holes, inject plastic on the surface of the die-casting aluminum alloy, enable the plastic to be immersed in the nanometer micropores through the chemical action of the plastic and the film, and enable the plastic and the die-casting aluminum alloy to be firmly bonded and combined into a whole to realize integrated molding.

Preferably, in the step 1), black ash is removed from the surface of the die-casting aluminum alloy by using an ash remover in the cleaning process; since silicon is easy to chemically react with acid/alkali, in the cleaning process, alkaline solution for cleaning can chemically react with silicon to form a layer of black ash on the surface of the die-casting aluminum alloy, so that certain influence is generated on the subsequent surface treatment process, especially in the TRI treatment process, the treatment of manufacturing the nano micropores on the surface of the die-casting aluminum alloy can be greatly influenced, if the black ash is not completely treated, the black ash can be attached to the upper surfaces of the nano micropores, the subsequent nano injection molding can be greatly influenced, and the aluminum-plastic bonding strength is poor. Therefore, the ash remover can be properly adopted to remove the black ash so as to ensure the subsequent TRI treatment process; the ash remover can also be used for removing black ash in the subsequent treatment process.

3) CNC machining, namely performing CNC machining on the die-casting aluminum alloy subjected to TRI treatment in the step 2); can be adjusted according to different application requirements without limitation.

4) Carrying out sand blasting treatment on the surface of the die-casting aluminum alloy subjected to CNC processing in the step 3); in the step, through carrying out sand blasting treatment on the surface of the die-casting aluminum alloy, the black ash on the surface of the die-casting aluminum alloy can be removed by utilizing high-speed sand blasting, and meanwhile, a sand surface protective layer is formed on the surface and can isolate chemical reaction between silicon and alkali in the die-casting aluminum alloy material and prevent the surface of the die-casting aluminum alloy from being corroded by acid and alkali.

Specifically, the blasting environment is as follows: using a pressure type sand blasting machine, setting the air pressure to be 0.5-1.5 kgf/cm²The walking speed is 1.5-2.5 m/min (equivalent to the motor rotation frequency is 15-25 Hz), and the swing frequency is 40-45 Hz. The air pressure is a compressed air pressure, and the pressure of the sand grains sprayed to the surface of the die-cast aluminum alloy on the surface of the die-cast aluminum alloy is adjusted by controlling the compressed air pressure. Sand blastingThe swinging frequency of the machine nozzle is the number of times that the nozzle swings left and right 45 degrees to return to the initial position at the position vertical to the die-casting aluminum alloy within unit time, and the swinging frequency is controlled to adjust the uniformity of sand blasting and achieve the aim of overall sand blasting. The running speed is the conveying speed and represents the moving distance of the die-cast aluminum alloy in unit time. Furthermore, the distance between the nozzle of the sand blasting machine and the die-casting aluminum alloy is 20-100 mm, and preferably, the distance between the nozzle of the sand blasting machine and the die-casting aluminum alloy is 50-80 mm, so that the uniformity of sand blasting treatment is improved. The sand used in the sand blasting treatment of the invention is zircon sand which is a sphere and has the advantages of good roundness, smooth surface, easy cleaning and the like, and can also adopt sand such as nylon sand, carborundum, white corundum, ceramic and the like.

Further, the die-cast aluminum alloy can also remove black dust on the surface thereof by high-speed blasting during the blasting process. The grain size, pressure, walking speed and swinging frequency of the sand blasting influence the cleaning degree of siliceous materials and black ash on the surface of the die-casting aluminum alloy, and influence the dust removing effect of the die-casting aluminum alloy. In order to determine the influence of the pressure and the walking speed on the ash removal effect, example verification of different particle sizes, pressures and walking speeds is required. (as shown in the following table)

The following detailed description of preferred embodiments of the invention

Example 1

The invention provides a method for removing black ash from a die-casting aluminum alloy, which comprises the following steps:

1) cleaning the die-casting aluminum alloy obtained by die-casting molding; in the step, clean water is adopted to clean the surface of the die-casting aluminum alloy;

2) carrying out TRI treatment on the cleaned die-casting aluminum alloy;

4) put into the sand blasting machine with the die-casting aluminum alloy and carry out sand blasting treatment, the environment setting of sandblast is: qi (Qi)The pressure was 0.5kgf/cm²The walking speed is 2.5m/min (equivalent to 25Hz of the rotating speed of the motor), the swing frequency is 45Hz, sand grains adopted by sand blasting are 120-mesh zircon sand, and the adhesion test is carried out on the die-casting aluminum alloy subjected to sand blasting to obtain comparison data shown in a table;

5) and carrying out anodic oxidation treatment on the die-casting aluminum alloy subjected to sand blasting treatment to obtain a die-casting aluminum alloy finished product. In the present embodiment, the anodic oxidation treatment is a treatment process conventional in the art, and preferably, the die-casting aluminum alloy after the sand blasting treatment is placed in an electrolytic bath filled with an electrolyte and supplied with direct current for anodic treatment, so as to form an oxide film layer on the surface of the die-casting aluminum alloy.

Example 2

1) cleaning the die-casting aluminum alloy obtained by die-casting molding; in the step, clean water is adopted to clean the surface of the die-casting aluminum alloy; and removing black ash on the surface of the die-casting aluminum alloy by using an ash remover in the cleaning process.

2) Carrying out TRI treatment on the cleaned die-casting aluminum alloy;

4) put into the sand blasting machine with the die-casting aluminum alloy and carry out sand blasting treatment, the environment setting of sandblast is: the air pressure was 0.6kgf/cm²The running speed is 2.5m/min (equivalent to 25Hz of the rotating speed of the motor), the swinging frequency is 45Hz, and the sand grains adopted by the sand blasting treatment are 120-mesh zircon sand. Carrying out adhesion test on the die-casting aluminum alloy subjected to sand blasting to obtain comparison data shown in a table;

5) and carrying out anodic oxidation treatment on the die-casting aluminum alloy subjected to sand blasting treatment to obtain a die-casting aluminum alloy finished product. In this example, the die-cast aluminum alloy after the sand blasting treatment was placed in an electrolytic bath filled with an electrolyte and supplied with direct current for anodic treatment, and an oxide film layer was formed on the surface of the die-cast aluminum alloy.

Example 3

1) cleaning the die-casting aluminum alloy obtained by die-casting molding; in the step, deionized purified water is adopted to clean the surface of the die-casting aluminum alloy;

2) carrying out TRI treatment on the cleaned die-casting aluminum alloy;

4) put into the sand blasting machine with the die-casting aluminum alloy and carry out sand blasting treatment, the environment setting of sandblast is: the air pressure was 1.0kgf/cm²The running speed is 2.5m/min (equivalent to 25Hz of the motor rotating speed), the swinging frequency is 43Hz, and the sand grains adopted by the sand blasting treatment are 205-mesh zircon sand. Carrying out adhesion test on the die-casting aluminum alloy subjected to sand blasting to obtain comparison data shown in a table;

Example 4

2) carrying out TRI treatment on the cleaned die-casting aluminum alloy;

4) put into the sand blasting machine with the die-casting aluminum alloy and carry out sand blasting treatment, the environment setting of sandblast is: the air pressure was 1.5kgf/cm²The running speed is 2.5m/min (equivalent to 25Hz of the rotating speed of the motor), the swing frequency is 45Hz, and the sand adopted by the sand blasting treatment is nylon sand. Carrying out adhesion test on the die-casting aluminum alloy subjected to sand blasting to obtain comparison data shown in a table;

As shown in fig. 2 to 5, the mobile phone middle plate is adopted for example verification, the front surface and the back surface of the mobile phone middle plate are subjected to sand blasting and ash removing treatment, and can also be adjusted according to the appearance requirement of a workpiece, or the part which does not need sand blasting is subjected to shielding treatment by matching with a shielding jig. The invention uses 4 groups of different condition parameters to carry out sand blasting treatment, and carries out effect detection after the sand blasting treatment is finished.

The silica fume removing effect judging and detecting method comprises the following steps: performing an adhesion test on the centering plate by using a 3M adhesive tape, and visually observing the degree of black and gray adhesion on the 3M adhesive tape; or wiping the middle plate with dust-free cloth on site, and visually observing the degree of black and grey adhered to the dust-free cloth.

In the above test data, 4 groups of the embodiments can achieve ideal ash removal effect, wherein the air pressure is 0.5-1.5 kgf/cm²The swing frequency is 40-45 Hz, and the walking speed is 1.5-2.5 m/min in a sand blasting environment, so that the dust removing effect is optimal. In the embodiment, a plurality of different sprayed sand materials can be verified simultaneously, and due to the fact that the sand materials are different in particle size and hardness and different in ash removal effect, the best verified result of the invention is the zircon sand with the particle size of 205. In addition, the die-casting aluminum alloy of S33N is adopted in this embodiment, and similarly, the die-casting aluminum alloy with other component contents can also be adjusted in pressure, frequency and walking speed in the same experimental manner to achieve the best removal effect.

Preferably, in the step 4), the die-casting aluminum alloy after the sand blasting treatment is subjected to a cleaning treatment to remove residual sand grains on the surface of the die-casting aluminum alloy. Specifically, the sand blasting treatment is carried out by adopting finer sand grains to remove residual sand grains on the surface of the die-casting aluminum alloy, and the finer sand grains are utilized to blast off the larger sand grains remained on the surface of the metal workpiece, so that the cleaning treatment is simple, and the sand removing effect and the efficiency are higher; and the sand grains after sand blasting can be recycled, so that the cost is reduced, and the pollution is reduced. And removing residual sand grains on the surface of the die-casting aluminum alloy by using a brush, namely blowing by using a fan, and removing the residual sand grains on the surface of the die-casting aluminum alloy by using the brush. And when cleaning and hairbrush treatment are carried out, vibration treatment can be carried out on the die-casting aluminum alloy by using vibration sand removing equipment, and sand grains remained on the surface of the die-casting aluminum alloy can be removed.

5) Carrying out anodic oxidation treatment on the die-casting aluminum alloy subjected to sand blasting treatment to obtain a die-casting aluminum alloy finished product; in the step, the die-casting aluminum alloy after sand blasting treatment is taken out and placed in electrolyte, and a process of forming a layer of oxide film on the surface of the die-casting aluminum alloy is carried out under specific process conditions.

Preferably, in step 2), the method further comprises the step of polishing the TRI-treated die-cast aluminum alloy: in the step 3), the die-casting aluminum alloy subjected to sand blasting is subjected to fine polishing, and in the step 4), the die-casting aluminum alloy subjected to sand blasting is subjected to fine polishing. The processing mode can be adjusted according to different application requirements, and is not limited.

The present embodiment provides a die-cast aluminum alloy obtained according to the processing method for removing black ash from the surface of a die-cast aluminum alloy as described above; this embodiment still provides a cell-phone casing, and the cell-phone casing includes the medium plate, and this medium plate is foretell die-casting aluminum alloy.

The surface processing mode of the invention is not limited to the surface processing modes of grinding, sand blasting, oil removing, degreasing, polishing, water washing and the like, and other processing modes and surface processing modes can be selected according to actual production needs.

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above examples only express preferred embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A treatment method for removing black ash on the surface of a die-casting aluminum alloy is characterized by comprising the following steps:

1) cleaning the die-casting aluminum alloy obtained by die-casting molding;

2) carrying out TRI treatment on the cleaned die-casting aluminum alloy;

4) carrying out sand blasting treatment on the surface of the die-casting aluminum alloy after CNC machining;

2. The method for removing the black and grey on the surface of the die-casting aluminum alloy according to claim 1, characterized by comprising the following steps: in the step 2), the method further comprises the step of polishing the TRI-treated die-casting aluminum alloy.

3. The method for removing the black and grey on the surface of the die-casting aluminum alloy according to claim 1, characterized by comprising the following steps: in the step 4), the die-casting aluminum alloy subjected to sand blasting treatment is subjected to fine polishing treatment.

4. The method for removing the black and grey on the surface of the die-casting aluminum alloy according to claim 1, characterized by comprising the following steps: in step 4), the conditions of the blasting treatment are as follows: the air pressure is 0.5 to 1.5kgf/cm²The running speed is 1.5-2.5 m/min.

5. The method for processing black and gray removal from the surface of a die-cast aluminum alloy according to claim 4, characterized in that: in step 4), the conditions of the blasting treatment are as follows: air pressure of 1.0kgf/cm²The running speed is 2.5 m/min.

6. The method for processing black and gray removal from the surface of a die-cast aluminum alloy according to claim 4, characterized in that: in step 4), the conditions of the blasting treatment are as follows: the air pressure was 1.5kgf/cm²The running speed is 2.5 m/min.

7. The method for removing the black ash from the surface of the die-casting aluminum alloy as recited in claim 5, wherein the sand used for the sand blasting is zircon sand.

8. The method for removing the black and grey on the surface of the die-casting aluminum alloy according to claim 5, characterized in that: and step 4), performing fine polishing treatment on the die-casting aluminum alloy subjected to sand blasting treatment.

9. A die-cast aluminum alloy obtained by the method for treating the surface of a die-cast aluminum alloy according to any one of claims 1 to 8 to remove black ash.

10. A handset housing, comprising: the handset housing comprises a middle plate, the middle plate being the die-cast aluminum alloy of claim 9.