Continuous surface treatment process for multicolor hardware

Abstract

The invention relates to the technical field of hardware surface treatment, and particularly discloses a continuous surface treatment process for multicolor hardware, which comprises the following steps: S1, pretreatment: cleaning, degreasing and removing an oxide layer of the hardware to ensure that the surface of the hardware is clean; s2, bottom layer anodic oxidation is conducted, specifically, the hardware is put into an anodic oxidation tank containing electrolyte, and a layer of oxidation film is formed on the surface of the hardware; s3, the hardware is put into a dyeing tank to be subjected to primary dyeing treatment, and a ground color anodic oxide film layer is formed; s4, the hardware is dyed for the second time, and a surface color layer is formed; and S5, the hardware is cleaned, dried and polished, and a surface anodic oxide film pattern is formed. According to the method, two dyeing layers with different colors are formed on the surface of the hardware through two times of dyeing treatment, finally, a multi-color oxidation film layer is formed on the metal surface, the process is simple, and the finally formed oxidation film layer is good in binding force with a metal base material and good in abrasion resistance and corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of hardware surface treatment, and in particular discloses a continuous surface treatment process for multi-color hardware. Background Art

[0002] Hardware is widely used in industrial manufacturing, building decoration, household goods and other fields. These hardware often require a certain aesthetic appearance, corrosion resistance and mechanical properties. As the market's requirements for the aesthetics, texture and functionality of hardware continue to increase, traditional surface treatment processes can no longer meet the diverse application needs, especially in terms of multi-color and pattern processing.

[0003] Traditional processes can generally only form a single color. In order to enrich the color of the oxide film, the first anodizing dyeing treatment is generally performed to form a dyed film, and then a part of the dyed film is removed by etching or engraving to expose the substrate; after forming a protective layer or a shielding layer on the retained dyed film, the substrate part where the dyed film is removed is subjected to a second anodizing dyeing treatment, so that a multi-color effect is formed on the metal or alloy surface. This method requires two anodizing treatments. During the second anodizing, the oxidation time cannot be too long, otherwise the oxide film formed by the first anodizing is easily punctured and falls off; if the oxidation time is too short, the oxidation degree is insufficient and the pores are small, which makes dyeing more difficult. The process is complicated, difficult to operate, and has high energy consumption. At the same time, due to the influence of the second anodizing treatment, the corrosion resistance and wear resistance of the oxide film formed for the first time are reduced. Generally, a polymer material layer needs to be coated for protection, but after the polymer material protective layer is coated, the surface of the workpiece loses the unique texture of the oxide film. Summary of the invention

[0004] In order to overcome the shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a continuous surface treatment process for multi-color hardware with simple process, good bonding between the oxide film layer and the metal substrate, and good wear resistance and corrosion resistance.

[0005] To achieve the above-mentioned purpose, a continuous surface treatment process for multi-color hardware of the present invention comprises the following steps: S1, pretreatment, cleaning, degreasing and removing the oxide layer of the hardware to ensure that the surface of the hardware is clean; S2, bottom anodizing, placing the hardware obtained in step S1 into an anodizing tank containing an electrolyte, and forming an oxide film on the surface of the hardware; S3, primary dyeing, placing the hardware obtained in step S2 into a dyeing tank for the first dyeing treatment to form a base color anodized film layer; S4, secondary dyeing, performing a second dyeing treatment on the hardware obtained in step S3 to form a surface color layer; S5, cleaning, drying and polishing the hardware obtained in step S4 to remove part of the surface color layer, correspondingly exposing the base color anodized film layer of the lower layer, and forming a surface anodized film pattern. The present invention forms two layers of dyeing layers of different colors on the surface of the hardware through two dyeing treatments, and finally forms a multi-color oxide film layer on the metal surface. The process is simple, and the oxide film layer finally formed has good bonding force with the metal substrate and good wear resistance and corrosion resistance.

[0006] Furthermore, the specific operation steps of step S1 include: S11, placing the hardware into a cleaning solution, the cleaning solution is a sodium hydroxide solution with a concentration of 250-450g / L, and at the same time, adding 40-50g / L sodium nitrate and 40-70g / L longevity alkali additive solution to the solution, controlling the temperature at 80-90°C, and the processing time is 30S-45S, removing the natural oxide film and stains on the surface of the hardware, so that the surface of the hardware achieves a matte or sand surface effect; S12, washing the hardware obtained in step S11 with water and placing it in a neutralizing solution, the neutralizing solution is a nitric acid solution with a concentration of 10%-20%, and treating at room temperature for 30-180 seconds to remove the ash stains insoluble in alkali and form a passivation film on the surface of the hardware; S13, placing the hardware obtained in step S12 into an ultrasonic cleaning machine for ultrasonic cleaning, and drying. The function of this alkaline cleaning is to dissolve the natural oxide film on the surface of hardware, slightly level the mechanical lines on the surface, and remove slight oil stains on the surface of hardware. Ultrasonic cleaning can also deeply remove pollutants, reduce the problem of uneven color in subsequent processing, and provide the best adhesion surface for the anodized film.

[0007] Furthermore, the ultrasonic cleaning machine includes a frame, a first conveyor for loading is provided at one end of the frame, a second conveyor for unloading is provided at the other end, and a plurality of slots are provided on the frame, the slot near the end of the first conveyor is an ultrasonic cleaning slot, and the slot near the end of the second conveyor is a drying slot. By setting two groups of conveyors, which are responsible for slots in different areas, the return time of the vehicle is reduced and the cleaning efficiency is improved; at the same time, the conveyor enables the hardware to be smoothly transferred in the assembly line, avoiding interruptions caused by manual operation, and improving the cleaning effect and production efficiency.

[0008] Furthermore, the polishing process in step S5 is mechanical polishing, tumbling, grinding or grinding. The selection of a variety of polishing methods can meet the needs of different surface effects, so that the hardware has richer changes in color levels. Different polishing techniques are suitable for different materials and surface requirements, which improves the diversity and aesthetics of multi-color patterns.

[0009] Furthermore, the primary dyeing treatment in step S3 includes immersing the bottom anodized hardware obtained in step S2 in a dye solution, wherein the dye solution is an aqueous solution of a dye, the dye solution is an azo dye, an anthraquinone dye or a phthalocyanine dye, the concentration of the dye in the dye solution is 0.1-8.5 g / L, the dye solution temperature is 25-50° C., and the immersion time is 1-12 minutes. Appropriate dye type and concentration can ensure color stability and durability. Strict control of dyeing temperature and time allows the dye to penetrate evenly and the base color layer to be stable, laying a uniform color foundation for subsequent dyeing and pattern processing.

[0010] Furthermore, the secondary dyeing process in step S4 is the same as the primary dyeing process in step S3, the dye for the primary dyeing is the same as the dye for the secondary dyeing, and the concentration of the dye liquor for the primary dyeing is different from that of the dye liquor for the secondary dyeing. By using similar processes and slightly different dye liquor conditions, complicated additional equipment and procedures are avoided, which not only ensures the simplification of the production process, but also can achieve clear color stratification and three-dimensional effects, thereby enhancing the diversity and visual effects of the products.

[0011] Furthermore, the bottom anodizing in step S2 includes using the hardware as an anode and the graphite plate as a cathode, placing the hardware in an anodizing tank containing an electrolyte for oxidation, wherein the electrolyte is a sulfuric acid solution with a concentration of 130-200 g / L, and the voltage of the bottom anodizing treatment is 12-16 volts and the current density is 0.5-1.5 A / dm 2 , the temperature is 20-25℃, and the time is 30-60 minutes. By precisely controlling the electrochemical parameters, the oxide film layer is made thick and uniform, which improves the corrosion resistance and color adhesion of the hardware surface and ensures the consistency of the subsequent dyeing and polishing effects.

[0012] Furthermore, in step S2, an ultrasonic generator is provided in the bottom anodizing tank to assist anodizing by ultrasonic waves.

[0013] Furthermore, the specific operation steps of step S2 include: S21, placing the hardware into the anodizing tank, powering on and starting the ultrasonic generator in the anodizing tank, and forming a first layer of oxide film on the surface of the hardware; S22, taking out the hardware to cool down, and when the temperature drops to the set value, placing the hardware into the anodizing tank again, powering on and starting the ultrasonic generator in the anodizing tank, and forming a second layer of oxide film on the surface of the hardware; S23, taking out the hardware to cool down, and when the temperature drops to the set value, placing the hardware into the anodizing tank again, powering on and starting the ultrasonic generator in the anodizing tank, and forming a third layer of oxide film on the surface of the hardware.

[0014] The bottom oxide film is subjected to multiple anodizing coatings to improve its compactness and make the product surface present a rich sense of layering and three-dimensionality. The outer oxide film is subjected to a single anodizing coating to ensure production efficiency. During the anodizing process, the vibration of ultrasound can accelerate the flow and diffusion of electrolytes and promote the oxidation reaction. The tiny bubbles generated by ultrasound will produce a strong impact when they burst, which will help the oxide layer to better adhere to the metal surface and improve the uniformity and quality of the oxide film.

[0015] Further, the cleaning tank in step S1, the anodizing tank in step S2 and the dyeing tank in step S3 are all provided with a sensor group, which includes a temperature sensor, a pH sensor, a current sensor, a concentration sensor and a liquid level sensor; the temperature sensor is used to monitor the temperature in the tank, the pH sensor is used to monitor the pH value of the liquid in the tank, the current sensor is used to monitor the current size during the anodizing process and the dyeing process, the concentration sensor is used to monitor the concentration of the liquid in the tank, and the liquid level sensor is used to monitor the liquid level of the liquid in the tank. The temperature sensor ensures that the treatment is carried out within a suitable temperature range to avoid adverse effects on the anodizing effect and the dyeing effect caused by too high or too low temperature; the pH sensor helps to adjust and maintain the appropriate pH to ensure that the anodizing reaction and the dyeing reaction proceed normally and avoid problems caused by pH deviation; the current sensor helps to control the current density to ensure that the treatment is carried out within a safe range and avoid problems caused by too large or too small current; the concentration sensor helps to adjust the amount of dye added to ensure uniform and stable color; the liquid level sensor ensures sufficient supply and circulation of anodizing liquid and dyeing liquid to avoid problems caused by insufficient liquid level or overflow.

[0016] Beneficial effects of the present invention: The present invention forms two dyeing layers of different colors on the surface of the hardware through two dyeing treatments, and finally forms a multi-color oxide film layer on the metal surface. The process is simple, and the oxide film layer finally formed has good bonding strength with the metal substrate and good wear resistance and corrosion resistance.

[0017] By setting up two sets of conveying devices, which are responsible for slots in different areas, the return time of the driving can be reduced and the cleaning efficiency can be improved; at the same time, the conveying device enables the hardware to be smoothly transferred in the assembly line, avoiding interruptions caused by manual operation, and improving the cleaning effect and production efficiency;

[0018] Appropriate dye types and concentrations can ensure color stability and durability. Strict control of dyeing temperature and time ensures uniform dye penetration and a stable base color layer, laying a uniform color foundation for subsequent dyeing and pattern processing.

[0019] Through similar processes and slightly different dyeing liquid conditions, complex additional equipment and procedures are avoided, which not only ensures the simplification of the production process, but also achieves clear color layering and three-dimensional effects, enhancing the diversity and visual effects of the products. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a process flow chart of a continuous surface treatment process of multi-color hardware of the present invention;

[0021] Figure 2 It is a structural schematic diagram of the ultrasonic cleaning machine of the present invention;

[0022] Figure 3 It is a structural schematic diagram of the picking member of the present invention;

[0023] Figure 4 It is a structural schematic diagram of the vibration grinding machine of the present invention;

[0024] Figure 5 It is a cross-sectional view of the vibration grinding machine of the present invention.

[0025] Reference numerals include:

[0026] 1. Ultrasonic cleaning machine; 2. Frame; 3. First conveying device; 4. Second conveying device; 5. Ultrasonic cleaning tank; 6. Drying tank; 7. Fixed bracket; 8. First horizontal slide rail; 9. First picking piece; 10. Second picking piece; 11. Base; 12. Clamping piece; 13. Vibration grinder; 14. Grinding device; 15. Center column; 16. Grinding ring groove; 17. Lifting hopper; 18. Hopper sleeve; 19. Annular trough; 20. Filter hole; 21. Support plate; 22. Unloading slot; 23. Front arm lifting rod; 24. Rear arm lifting rod. DETAILED DESCRIPTION

[0027] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0028] See also Figures 1 to 5As shown, a continuous surface treatment process for multi-color hardware of the present invention comprises the following steps: S1, pretreatment, cleaning, degreasing and removing the oxide layer of the hardware to ensure that the surface of the hardware is clean; S2, bottom anodizing, placing the hardware obtained in step S1 into an anodizing tank containing an electrolyte, and forming an oxide film on the surface of the hardware; S3, primary dyeing, placing the hardware obtained in step S2 into a dyeing tank for the first dyeing treatment to form a base color anodized film layer; S4, secondary dyeing, performing a second dyeing treatment on the hardware obtained in step S3 to form a surface color layer; S5, cleaning, drying and polishing the hardware obtained in step S4 to remove part of the surface color layer, correspondingly exposing the base color anodized film layer of the lower layer, and forming a surface anodized film pattern. The present invention forms two layers of dyeing layers of different colors on the surface of the hardware through two dyeing treatments, and finally forms a multi-color oxide film layer on the metal surface. The process is simple, and the oxide film layer finally formed has good bonding strength with the metal substrate and good wear resistance and corrosion resistance.

[0029] Specifically, the continuous surface treatment process of the multi-color hardware also includes: step S6, sealing, the hardware obtained in step S5 is immersed in the sealing liquid for 5-10 minutes, the sealing liquid is a nickel-free metal salt with a concentration of 4-6g / L, a pH of 5.5-6.0, and a temperature of 70-80°C. The anodizing process basically generates an oxidized anodized film, which is a porous anodized film. It is composed of a barrier layer of a metal matrix and a porous layer film. Although this porous nature gives the oxide film coloring or dyeing into other functions, its corrosion resistance, weather resistance, and pollution resistance cannot meet practical requirements, so the micropores of the anodized film must be sealed. The unsealed anodized film increases the area of ​​the workpiece exposed to the environment due to the large amount of micropores in the pores, and the corresponding corrosion area will also increase. Therefore, sealing is a very important process for anodizing aluminum.

[0030] The specific operation steps of step S1 include: S11, putting the hardware into a cleaning solution, the cleaning solution is a sodium hydroxide solution with a concentration of 250-450g / L, and at the same time, adding 40-50g / L sodium nitrate and 40-70g / L longevity alkali additive solution to the solution, controlling the temperature at 80-90°C, and treating for 30S-45S, removing the natural oxide film and stains on the surface of the hardware, so that the surface of the hardware achieves a matte or sand surface effect; S12, washing the hardware obtained in step S11 with water and then putting it into a neutralizing solution, the neutralizing solution is a nitric acid solution with a concentration of 10%-20%, treating at room temperature for 30 to 180 seconds, removing the ash stains insoluble in alkali, and forming a passivation film on the surface of the hardware; S13, putting the hardware obtained in step S12 into an ultrasonic cleaning machine 1 for ultrasonic cleaning, and drying. The function of this alkaline cleaning is to dissolve the natural oxide film on the surface of hardware, slightly level the mechanical lines on the surface, and remove slight oil stains on the surface of hardware. Ultrasonic cleaning can also deeply remove pollutants, reduce the problem of uneven color in subsequent processing, and provide the best adhesion surface for the anodized film.

[0031] The ultrasonic cleaning machine 1 comprises a frame 2, a first conveying device 3 for loading is provided at one end of the frame 2, a second conveying device 4 for unloading is provided at the other end, and a plurality of slots are provided on the frame 2, the slot near one end of the first conveying device 3 is an ultrasonic cleaning slot 5, and the slot near one end of the second conveying device 4 is a drying slot 6. By setting two sets of conveying devices, which are responsible for slots in different areas, the return time of the driving is reduced and the cleaning efficiency is improved; at the same time, the conveying device enables the hardware to be smoothly transferred in the assembly line, avoiding interruptions caused by manual operation, and improving the cleaning effect and production efficiency.

[0032] Specifically, the ultrasonic cleaning tank 5 is used to clean the hardware obtained in step S12, and the drying tank 6 is used to dry the hardware cleaned in the ultrasonic cleaning tank 5.

[0033] Specifically, a fixed bracket 7 is provided on the rear side of the frame 2, a first horizontal slide rail 8 is provided on the fixed bracket 7, two groups of picking parts are slidably provided on the first horizontal slide rail 8, a first picking part 9 close to the first conveying device 3 is used to transfer the hardware from the first conveying device 3 to the slot position, and the second picking part 10 is used to transfer the hardware from the slot position to the second conveying device 4.

[0034] Specifically, the ultrasonic cleaning machine 1 also includes a control console, which can not only control the operation of all electrical equipment on the ultrasonic cleaning machine 1, but also control the switches for water replenishment and drainage in the slot. A water level detector and a water impurity detector are provided in the slot. When the impurities are cleaned, the water quality in the slot still does not meet the standard. The control console controls the drainage switch of the slot to automatically drain the water. After the drainage is completed, the automatic water replenishment switch is turned on for water replenishment. When the water level reaches the height threshold set by the water impurity detector, the automatic water replenishment switch of the console is turned off. This control method can automatically drain and replenish water without stopping the production process, thereby ensuring the cleanliness of the product, saving the downtime of the staff's manual water changing equipment, and effectively improving production capacity.

[0035] Specifically, the picking component includes a base 11 , a clamping component 12 slidably disposed on the base 11 , and a cylinder, and the cylinder drives the clamping component 12 to rise and fall relative to the base 11 .

[0036] The bottom layer anodization in step S2 includes taking the hardware as the anode and the graphite plate as the cathode, placing the hardware in an anodizing tank containing an electrolyte for oxidation, wherein the electrolyte is a sulfuric acid solution with a concentration of 130-200g / L, and the bottom layer anodization treatment voltage is 12-16 volts, the current density is 0.5-1.5A / dm2, the temperature is 20-25°C, and the time is 30-60 minutes. By precisely controlling the electrochemical parameters, the oxide film layer is made thick and uniform, which improves the corrosion resistance and color adhesion of the surface of the hardware, and ensures the consistency of the effect of subsequent dyeing and polishing.

[0037] In step S2, an ultrasonic generator is provided in the bottom anodizing tank to assist anodizing by ultrasonic waves.

[0038] The specific operation steps of step S2 include: S21, placing the hardware into the anodizing tank, powering on and starting the ultrasonic generator in the anodizing tank, and forming a first oxide film on the surface of the hardware;

[0039] S22, take out the hardware to cool down. When the temperature drops to the set value, put the hardware into the anodizing tank again, turn on the power and start the ultrasonic generator in the anodizing tank to form a second layer of oxide film on the surface of the hardware; S23, take out the hardware to cool down. When the temperature drops to the set value, put the hardware into the anodizing tank again, turn on the power and start the ultrasonic generator in the anodizing tank to form a third layer of oxide film on the surface of the hardware.

[0040] The bottom oxide film is subjected to multiple anodizing coatings to improve its compactness and make the product surface present a rich sense of layering and three-dimensionality. The outer oxide film is subjected to a single anodizing coating to ensure production efficiency. During the anodizing process, the vibration of ultrasound can accelerate the flow and diffusion of electrolytes and promote the oxidation reaction. The tiny bubbles generated by ultrasound will produce a strong impact when they burst, which will help the oxide layer to better adhere to the metal surface and improve the uniformity and quality of the oxide film.

[0041] The primary dyeing treatment in step S3 includes immersing the bottom anodized hardware obtained in step S2 in a dye solution, wherein the dye solution is an aqueous solution of a dye, and the dye solution is an azo dye, an anthraquinone dye or a phthalocyanine dye, and the concentration of the dye in the dye solution is 0.1-8.5 g / L, the dye solution temperature is 25-50° C., and the immersion time is 1-12 minutes. Appropriate dye type and concentration can ensure color stability and durability. Strict control of dyeing temperature and time allows the dye to penetrate evenly and the base color layer to be stable, laying a uniform color foundation for subsequent dyeing and pattern processing.

[0042] The secondary dyeing process in step S4 is the same as the primary dyeing process in step S3, the dye for the primary dyeing is the same as the dye for the secondary dyeing, and the concentration of the dye liquor for the primary dyeing is different from that of the dye liquor for the secondary dyeing. Through similar processes and slightly different dye liquor conditions, complicated additional equipment and procedures are avoided, which not only ensures the simplification of the production process, but also can achieve clear color stratification and three-dimensional effects, thereby enhancing the diversity and visual effects of the products.

[0043] The polishing process in step S5 is mechanical polishing, tumbling, grinding or grinding. The selection of multiple polishing methods can meet the needs of different surface effects, so that the hardware has richer changes in color levels. Different polishing techniques are suitable for different materials and surface requirements, which improves the diversity and aesthetics of multi-color patterns.

[0044] Specifically, the polishing process in step S5 is to put the hardware into a vibration grinder 13 for grinding. The vibration grinder 13 includes a grinding device 14. A central column 15 is provided at the center of the grinding device 14. A grinding ring groove 16 is formed between the central column 15 and the inner wall of the grinding device 14. A lifting hopper 17 is sleeved above the grinding device 14. A hopper sleeve 18 is provided at a position corresponding to the lifting hopper 17 and the central column 15. The hopper sleeve 18 is sleeved on the central column 15. The hopper sleeve 18 and the lifting hopper 17 form a ring. A shaped material trough 19 is provided with a filter hole 20 in the annular material trough 19, and the filter hole 20 is used to filter the grinding material. A support plate 21 is provided on the upper edge of the lifting hopper 17, and a material discharge slot 22 is provided on one side of the lifting hopper 17. A front arm lifting rod 23 is provided on the outer wall of the grinding device 14 close to the material discharge slot 22, and a rear arm lifting rod 24 is provided on the outer wall of the grinding device 14 away from the material discharge slot 22. The telescopic ends of the front arm lifting rod 23 and the rear arm lifting rod 24 are both hinged to the support plate 21, and a conveying device is correspondingly provided at the end of the material discharge slot 22.

[0045] Specifically, when the lifting hopper 17 and the grinding device 14 are fully fitted, the front arm lifting rod 23 and the rear arm lifting rod 24 are both in the shortest arm length state, and a pressure sensor is provided at the connection between the front arm electric lifting rod and the support plate 21.

[0046] The cleaning tank in step S1, the anodizing tank in step S2 and the dyeing tank in step S3 are all equipped with a sensor group, which includes a temperature sensor, a pH sensor, a current sensor, a concentration sensor and a liquid level sensor; the temperature sensor is used to monitor the temperature in the tank, the pH sensor is used to monitor the pH value of the liquid in the tank, the current sensor is used to monitor the current size during the anodizing process and the dyeing process, the concentration sensor is used to monitor the concentration of the liquid in the tank, and the liquid level sensor is used to monitor the liquid level of the liquid in the tank. The temperature sensor ensures that the treatment is carried out within the appropriate temperature range to avoid the adverse effects of too high or too low temperature on the anodizing effect and the dyeing effect; the pH sensor helps to adjust and maintain the appropriate pH to ensure that the anodizing reaction and the dyeing reaction proceed normally and avoid problems caused by pH deviation; the current sensor helps to control the current density to ensure that the treatment is carried out within the safe range and avoid problems caused by too large or too small current; the concentration sensor helps to adjust the amount of dye added to ensure uniform and stable color; the liquid level sensor ensures sufficient supply and circulation of anodizing liquid and dyeing liquid to avoid problems caused by insufficient liquid level or overflow.

[0047] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A continuous surface treatment process for multi-color hardware, characterized in that: The following steps are involved: S1. Pretreatment: cleaning, degreasing and removing oxidation layer of hardware to ensure the surface of hardware is clean; S2, bottom layer anodization, placing the hardware obtained in step S1 into an anodizing tank containing electrolyte, and forming an oxide film on the surface of the hardware; S3, primary dyeing, placing the hardware obtained in step S2 into a dyeing tank for a first dyeing treatment to form a base color anodized film layer; S4, secondary dyeing, performing a second dyeing treatment on the hardware obtained in step S3 to form a surface color layer; S5. Clean, dry and polish the hardware obtained in step S4 to remove part of the surface color layer, thereby exposing the bottom color anodized film layer of the lower layer to form a surface anodized film pattern.

2. The continuous surface treatment process for multi-color hardware according to claim 1, characterized in that: The specific operation steps of step S1 include: S11. Put the hardware into a cleaning solution, which is a sodium hydroxide solution with a concentration of 250-450g / L, and add 40-50g / L sodium nitrate and 40-70g / L longevity alkali additive solution to the solution, control the temperature at 80-90°C, and process for 30S-45S to remove the natural oxide film and stains on the surface of the hardware, so that the surface of the hardware has a matte or sand surface effect; S12, washing the hardware obtained in step S11 with water and then placing it in a neutralizing solution, wherein the neutralizing solution is a nitric acid solution with a concentration of 10%-20%, treating at room temperature for 30-180 seconds to remove the ash stains insoluble in alkali and form a passivation film on the surface of the hardware; S13, placing the hardware obtained in step S12 into an ultrasonic cleaning machine (1) for ultrasonic cleaning, and drying.

3. The continuous surface treatment process for multi-color hardware according to claim 2 is characterized in that: The ultrasonic cleaning machine (1) comprises a frame (2), one end of the frame (2) is provided with a first conveying device (3) for loading materials, and the other end is provided with a second conveying device (4) for unloading materials. The frame (2) is provided with a plurality of slots, the slot near one end of the first conveying device (3) is an ultrasonic cleaning slot (5), and the slot near one end of the second conveying device (4) is a drying slot (6).

4. The continuous surface treatment process for multi-color hardware according to claim 1 is characterized in that: The polishing process in step S5 is mechanical polishing, tumbling, grinding or grinding.

5. The continuous surface treatment process for multi-color hardware according to claim 1 is characterized in that: The primary dyeing treatment in step S3 includes immersing the bottom anodized hardware obtained in step S2 in a dye solution, wherein the dye solution is an aqueous solution of a dye, and the dye solution is an azo dye, an anthraquinone dye or a phthalocyanine dye, the concentration of the dye in the dye solution is 0.1-8.5 g / L, the dye solution temperature is 25-50° C., and the immersion time is 1-12 minutes.

6. The continuous surface treatment process for multi-color hardware according to claim 5, characterized in that: The secondary dyeing process in step S4 is the same as the process of the primary dyeing process in step S3 , the dye for the primary dyeing is the same as the dye for the secondary dyeing, and the concentration of the dye solution for the primary dyeing is different from that of the dye solution for the secondary dyeing.

7. The continuous surface treatment process for multi-color hardware according to claim 1, characterized in that: The bottom layer anodization in step S2 includes using the hardware as the anode and the graphite plate as the cathode, placing the hardware in an anodizing tank containing an electrolyte for oxidation, the electrolyte being a sulfuric acid solution with a concentration of 130-200 g / L, the bottom layer anodization treatment voltage being 12-16 volts, the current density being 0.5-1.5 A / dm2, the temperature being 20-25°C, and the time being 30-60 minutes.

8. The continuous surface treatment process for multi-color hardware according to claim 7, characterized in that: In the step S2, an ultrasonic generator is provided in the bottom anodizing tank to assist anodizing by ultrasonic waves.

9. The continuous surface treatment process for multi-color hardware according to claim 8, characterized in that: The specific operation steps of step S2 include: S21, placing the hardware into an anodizing tank, powering on and starting the ultrasonic generator in the anodizing tank, and forming a first oxide film on the surface of the hardware; S22, take out the hardware and cool it down. When the temperature drops to the set value, put the hardware into the anodizing tank, power on and start the ultrasonic generator in the anodizing tank to form a second oxide film on the surface of the hardware; S23, take out the hardware and cool it down. When the temperature drops to the set value, put the hardware into the anodizing tank, power on and start the ultrasonic generator in the anodizing tank to form a third oxide film on the surface of the hardware.

10. The continuous surface treatment process for multi-color hardware according to claim 1, characterized in that: The cleaning tank in step S1, the anodizing tank in step S2 and the dyeing tank in step S3 are all provided with a sensor group, and the sensor group includes a temperature sensor, a pH value sensor, a current sensor, a concentration sensor and a liquid level sensor; the temperature sensor is used to monitor the temperature in the tank, the pH value sensor is used to monitor the pH value of the liquid in the tank, the current sensor is used to monitor the current size during the anodizing process and the dyeing process, the concentration sensor is used to monitor the concentration of the liquid in the tank, and the liquid level sensor is used to monitor the liquid level of the liquid in the tank.

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