Electrophoresis process

Abstract

The invention provides an electrophoresis process which is characterized in that a part to be subjected to electrophoresis is hung on a hanger, and the hanger is conveyed to an electrophoresis line. The electrophoresis process comprises the following steps: S1, pre-degreasing and showering; s2, ultrasonic degreasing; s3, ultrasonic clean water cleaning; s4, surface conditioning and showering; s5, phosphating treatment is carried out; s6, performing cathode electrophoresis; s7, performing ultrafiltration cleaning; s8, curing is conducted; and S9, cooling. The rapid, firm and uniform coating operation on the part can be realized by designing an efficient and stable electrophoresis process.

Description

Technical Field

[0001] The present invention relates to the technical field of electrophoresis processes, and in particular to an electrophoresis process. Background Art

[0002] As a key load-bearing component of an automobile, the cast iron steering knuckle needs to have high corrosion resistance and wear resistance. This requires the use of an electrophoretic process to apply a protective coating on the part to increase its corrosion resistance.

[0003] The traditional electrophoretic coating process only involves a simple immersion coating followed by drying. This process results in incomplete degreasing, uneven phosphate film, and poor adhesion of the electrophoretic coating, which can lead to easy peeling of the coating and insufficient corrosion resistance. Therefore, an efficient, stable, and suitable electrophoretic coating process for cast iron steering knuckles is urgently needed. Summary of the Invention

[0004] In view of this, the present invention provides an electrophoretic process, which can achieve rapid, firm and uniform coating of parts by designing an efficient and stable electrophoretic process, solving the problems of incomplete degreasing, uneven phosphating film, poor adhesion of electrophoretic coating, which leads to easy peeling of coating and insufficient corrosion resistance in traditional electrophoretic process.

[0005] To solve the above technical problems, the present invention provides an electrophoresis process, wherein the parts to be electrophoresed are hung on a hanger, and the hanger is transported to the electrophoresis line. The electrophoresis process includes the following steps:

[0006] S1. Pre-degreasing and showering: Use a cleaning machine and a spray head to shower the parts at 35-45°C. The shower pressure is 0.05-0.1 MPa, the shower time is 1-2 minutes, and the total alkalinity of the shower liquid is 10-12 pt.

[0007] S2, ultrasonic degreasing, immerse the parts that have been pre-degreased and rinsed in S1 in ultrasonic degreasing liquid for degreasing. The degreasing time is 3-5 minutes, the degreasing temperature is 40-50℃, the total alkalinity of the degreasing liquid is 12-20pt, and the circulation pressure is 0.05-0.1Mpa;

[0008] S3, ultrasonic water cleaning, immerse the parts that have been ultrasonically degreased in S2 in clean water for ultrasonic cleaning, the cleaning time is 2-3 minutes, and the cleaning cycle pressure is 0.05-0.1Mpa;

[0009] S4, surface-adjusted shower, shower pressure is 0.05-0.1Mpa, shower time is 1-2min, and the pH value of the shower liquid is 8.5-12;

[0010] S5. Phosphating treatment: soak the parts after surface conditioning and rinsing and then place them in the phosphating tank for phosphating treatment. The phosphating time is 3-5 minutes; the circulating pressure is 0.05-0.1Mpa, the total acidity of the phosphating solution is 26-32pt, the free acid is 0.6-1.2pt, the accelerator is 2-3pt, and the temperature is 30-38℃;

[0011] S6. Cathodic electrophoresis: Immerse the cleaned parts after phosphating treatment in an electrophoresis tank for cathodic electrophoresis treatment. Control the pH value to be 5.6-6.1, the tank temperature to be 29-33°C, the electrophoresis tank liquid pigment to binder ratio P / B to be 8-12%, the solid content NV of the electrophoresis liquid to be 13-21%, the electrophoresis liquid conductivity to be 1000-1800us / cm, the electrophoresis tank liquid solvent content to be 0.5-1.2%, the operating voltage to be 260-300V, and the electrophoresis time to be 3-5min.

[0012] S7, ultrafiltration cleaning, the electrophoresis-treated parts are passed through the ultrafiltration filter again to clean the electrophoresis-treated auto parts; the flushing pressure is 0.05-0.1Mpa, and the cleaning time is 1-2min;

[0013] S8, curing, curing the cleaned and dried parts at a temperature of 220-240°C for 60-80 minutes;

[0014] S9, cooling, cooling the solidified parts, the cooling time is 30-60 minutes.

[0015] Two more showers are added between S3 and S4, with each shower having a pressure of 0.05-0.1 MPa and a shower time of 1-2 minutes.

[0016] Add three rinses between S5 and S6, of which the first rinse pressure is 0.05-0.1Mpa and the rinse time is 1-2min; the second rinse uses pure water, the rinse pressure is 0.05-0.1Mpa, and the rinse time is 1-2min; the third rinse uses fresh pure water, the rinse pressure is 0.05-0.1Mpa, and the rinse time is 1-2min; the conductivity is <50us / cm; the phosphate film thickness is: 1-3μm, the P ratio is greater than 85%, and the crystal size is less than 3μm.

[0017] In summary, compared with the prior art, this application has at least one of the following beneficial technical effects:

[0018] 1. Improving the uniformity and adhesion of the coating through an efficient electrophoretic process: The present invention can improve the crystal size or P ratio of the phosphate film to an appropriate level (the density ratio of zinc phosphate crystals in the phosphate film) by controlling the parameters of the degreasing and phosphating steps (such as temperature, time, pH) and the coordinated control of the electrophoretic process, thereby greatly improving the firmness and uniformity of the coating caused by electrophoresis.

[0019] 2. The present invention can achieve thorough removal of degreasing agent and grease residues by repeated rinsing after degreasing, and can achieve the removal of phosphates, metal ions (such as Zn 2+ ) and acidic components to prevent them from entering the electrophoresis tank, which will destroy the pH and conductivity balance of the tank liquid, and even react with the electrophoresis resin to generate particulate matter, affecting the adhesion of the coating.

[0020] 3. The present invention can be washed with pure water (conductivity <50μS / cm) to remove phosphates, metal ions (such as Zn 2+ ) and acidic components to avoid contaminating the coating.

[0021] 4. The present invention can adjust the surface chemical activity through surface conditioning and rinsing, promote the nucleation of the phosphate film, remove residual impurities, prevent phosphate pollution, optimize the phosphate film structure, and improve the coating performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is a process flow chart of the electrophoresis process of the present invention;

[0023] Figure 2 This is a comparison table of the detection results of the electrophoresis process of the present invention. DETAILED DESCRIPTION

[0024] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figure 1 and Figure 2 , clearly and completely describing the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments derived by ordinary technicians in this field fall within the scope of protection of the present invention.

[0025] like Figure 1 As shown: This embodiment provides an electrophoresis process, wherein the parts to be electrophoresed are hung on a hanger, and the hanger is transported to the electrophoresis line by an automatic conveyor chain for electrophoresis. The process includes the following steps:

[0026] S1. Pre-degreasing and showering: Use 35-45℃ pre-degreasing and showering on the surface of parts, with a showering pressure of 0.05-0.1Mpa and a showering time of 1-2min; the total alkalinity of the showering liquid is 10-12pt;

[0027] S2, ultrasonic degreasing, immerse the parts that have been pre-degreased and rinsed in S1 in ultrasonic degreasing liquid for degreasing. The degreasing time is 3-5 minutes, the degreasing liquid temperature is 40-50℃, the total alkalinity of the degreasing liquid is 12-20pt, and the circulation pressure is 0.05-0.1Mpa;

[0028] S3, ultrasonic water cleaning, immerse the parts that have been ultrasonically degreased in S2 in clean water for ultrasonic cleaning. The cleaning time is 2-3 minutes, the circulation pressure is 0.05-0.1Mpa, and the ultrasonic vibration is synchronized to effectively remove the degreasing agent residue;

[0029] S4, surface conditioning shower, shower pressure 0.05-0.1Mpa, shower time 1-2min, pH value 8.5-12, to form a uniform active layer on the surface of the parts;

[0030] S5. Phosphating treatment: soak the parts after surface conditioning and rinsing and then place them in the phosphating tank for phosphating treatment. The phosphating time is 3-5 minutes; the circulating pressure is 0.05-0.1Mpa, the total acidity is 26-32pt, the free acid is 0.6-1.2pt, the accelerator is 2-3pt, and the temperature is 30-38℃;

[0031] S6. Cathodic electrophoresis: Immerse the cleaned parts after phosphating treatment in an electrophoresis tank for cathodic electrophoresis treatment. Control the pH value to be 5.6-6.1, the tank temperature to be 29-33°C, the pigment-to-base ratio (P / B) of the electrophoresis tank to be 8-12%, the solid content (NV) of the electrophoresis solution to be 13-21%, the conductivity of the electrophoresis solution to be 1000-1800us / cm, the solvent content of the electrophoresis tank to be 0.5-1.2%, the operating voltage to be 260-300V, and the electrophoresis time to be 3-5min.

[0032] S7, ultrafiltration cleaning, the electrophoresis-treated parts are passed through an ultrafiltration filter to clean the electrophoresis-treated auto parts again, the flushing pressure is 0.05-0.1Mpa, the cleaning time is 1-2min, and the floating paint is recovered after ultrafiltration cleaning;

[0033] S8, curing, curing the cleaned and dried parts in an oven at a curing temperature of 220-240°C for 60-80 minutes to achieve complete cross-linking of the coating;

[0034] S9, cooling, cooling the solidified parts, the cooling liquid is cooled by air cooler, and the cooling time is 30-60 minutes.

[0035] Add at least two more showers between S3 and S4, with each shower having a pressure of 0.05-0.1 MPa and a shower time of 1-2 minutes, to further remove suspended particles.

[0036] According to one embodiment of the present invention, Figure 1 and Figure 2 As shown, at least three rinses are added between S5 and S6. This embodiment is described using three rinses as an example, wherein the first rinse has a pressure of 0.05-0.1 MPa and a duration of 1-2 min; the second rinse uses pure water with a pressure of 0.05-0.1 MPa and a duration of 1-2 min; the third rinse uses fresh pure water with a pressure of 0.05-0.1 MPa and a duration of 1-2 min; the conductivity is <50 us / cm, there is no liquid accumulation on the workpiece, no chemical residue, and the water film is continuous and uniform when wet; the appearance is oil-free and rust-free, without flowery or streaky appearance, and the phosphate film is uniform, dense and continuous; the phosphate film thickness is 1-3 μm, the P ratio is greater than 85%, and the crystal size is less than 3 μm. The first clean water rinse can remove phosphating slag on the surface of the part, and the second pure water rinse is combined with the third fresh pure water rinse to ensure that there is no ion residue.

[0037] The method of using the present invention:

[0038] First of all, it should be made clear that the electrophoresis process involved in the present invention is mainly used for electrophoresis operations on cast iron automobile parts. The present invention takes the electrophoresis of automobile steering knuckle as an example to explain its method of use in detail. When electrophoresis of automobile steering knuckle is required, the following steps are followed: first, hang the parts to be electrophoresed on the hanger, and transport the hanger to the electrophoresis line with the help of an automatic conveyor chain for electrophoresis, and then pre-degrease and rinse the parts; then ultrasonically degrease the parts; then ultrasonically clean the parts with water, and after the ultrasonic clean water cleaning is completed, rinse the parts twice, and then perform surface adjustment and rinse on the parts. The parts are then rinsed; the parts are then subjected to phosphating treatment; the parts are then rinsed three times, and then cathodic electrophoresis is performed on the parts; the parts are then cleaned by ultrafiltration; the parts are then rinsed with the recovery liquid four times, and then the parts are blown dry, which can be done with an air gun, and then the parts are transported into an oven for curing, and then the parts are cooled. The present invention can achieve rapid, firm and uniform coating of the parts through the above-mentioned electrophoresis process, which solves the problems of incomplete degreasing, uneven phosphating film, poor adhesion of the electrophoretic coating, easy peeling of the coating and insufficient corrosion resistance in the traditional electrophoresis process.

[0039] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0040] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An electrophoresis process, wherein the parts to be electrophoresed are hung on a hanger, and the hanger is transported to the electrophoresis line, characterized in that: The electrophoresis process includes the following steps: S1, pre-degreasing shower; S2, ultrasonic degreasing; S3, ultrasonic water cleaning; S4, surface-adjusted shower; S5, phosphating treatment; S6, cathodic electrophoresis; S7, ultrafiltration cleaning; S8, curing; S9. Cooling.

2. The electrophoresis process according to claim 1, wherein: In S1, the surface of automobile parts is pre-degreased and rinsed at 35-45°C, with a rinse pressure of 0.05-0.1Mpa, a rinse time of 1-2min, and a total alkalinity of 10-12pt.

3. The electrophoresis process according to claim 2, wherein: The degreasing time in S2 is 3-5 minutes, the temperature is 40-50°C, the total alkalinity is 12-20pt, and the circulating pressure is 0.05-0.1Mpa.

4. The electrophoresis process according to claim 3, wherein: The cleaning time in S3 is 2-3 minutes, and the circulation pressure is 0.05-0.1 MPa.

5. The electrophoresis process according to claim 4, wherein: Two more showers are added between S3 and S4, with each shower having a pressure of 0.05-0.1 MPa and a shower time of 1-2 minutes.

6. The electrophoresis process according to claim 1, wherein: The shower pressure in S4 is 0.05-0.1Mpa, the shower time is 1-2min, and the pH value is 8.5-12.

7. The electrophoresis process according to claim 6, wherein: The phosphating time in S5 is 3-5 minutes; the circulating pressure is 0.05-0.1 MPa, the total acidity is 26-32 pt, the free acid is 0.6-1.2 pt, the accelerator is 2-3 pt, and the temperature is 30-38°C.

8. The electrophoresis process according to claim 1, wherein: Add three flushing steps between S5 and S6, where the first flushing pressure is 0.05-0.1Mpa and the flushing time is 1-2min; the second flushing uses pure water with a flushing pressure of 0.05-0.1Mpa and the flushing time is 1-2min; the third flushing uses fresh pure water with a flushing pressure of 0.05-0.1Mpa and the flushing time is 1-2min; the conductivity is <50us / cm, the phosphate film thickness is 1-3μm, the P ratio is greater than 85%, and the crystal size is less than 3μm.

9. The electrophoresis process according to claim 1, wherein: In S6, the above-mentioned automobile parts are immersed in an electrophoresis tank for cathode electrophoresis treatment, and the pH value is controlled to be: 5.6-6.1, bath temperature: 29-33°C, electrophoresis bath pigment-to-base ratio P / B: 8-12%, electrophoresis bath solids content NV: 13-21%, electrophoresis bath conductivity: 1000-1800us / cm, electrophoresis bath solvent content: 0.5-1.2%, working voltage 260-300V, electrophoresis time 3-5min.

10. The electrophoresis process according to claim 1, wherein: The curing temperature in S8 is 220-240°C, and the curing time is 60-80 minutes.

Images