A method for preparing a riveted panel

Abstract

This invention provides a method for preparing a riveted panel, belonging to the field of machining technology. It includes the following steps: 1. Preparing a zinc alloy coating on the rivet screw; 2. Connecting the zinc alloy-coated rivet screw to the panel using a riveting machine; 3. Connecting the rivet screw to the panel at the riveting joint using welding, forming a continuous metal transition from aluminum to steel; 4. Polishing the weld seam with sandpaper; 5. Performing chemical oxidation treatment on the riveted panel and then electrostatically powder coating within 8 hours; 6. Uniformly spraying powder coating onto the surface of the workpiece using an electrostatic spray gun; 7. Heating and curing the powder coating. This invention repairs the annular pit at the riveting joint of the panel with brazing filler metal, forming a continuous metal transition from aluminum to steel, avoiding the Faraday cage effect during electrostatic powder coating, and completely solving the problem of rivet marks after spraying.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, and specifically relates to a method for preparing a riveted panel. Background Technology

[0002] Most cabinet and chassis panels require rivet screws for connection, followed by electrostatic powder coating on the riveted surfaces. However, a tiny annular pit inevitably exists at the rivet joint between the rivet screw and the panel. This pit is formed by the height difference between the panel and the rivet screw, making it impossible for them to be perfectly flush. During electrostatic powder coating, the Faraday cage effect often occurs, causing powder particles to concentrate at areas with lower electric field resistance (i.e., the edges of these recessed areas). Because the electric field strength increases at the edges, the powder particles move towards the edges, resulting in significant powder deposition in these areas, making it difficult for the powder to reach the recesses. Therefore, rivet marks often appear after coating.

[0003] The common solution to this problem is to apply conductive putty to the joint, dry it, polish it, and then apply electrostatic powder coating. However, this method has the following drawbacks: poor adhesion and low bonding strength; the surface is not smooth enough, has poor texture, and lacks toughness; it is prone to powdering when exposed to moisture; and cracking, peeling, and flaking of the conductive putty may occur after a certain period of time. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing a riveted panel. This production process is simple and easy to implement. It can not only solve the Faraday cage effect that occurs during the electrostatic powder spraying process, but also avoid the many drawbacks caused by the traditional conductive putty method.

[0005] The present invention solves the above-mentioned technical problems by adopting the following technical solutions:

[0006] A method for preparing a riveted panel, comprising the following steps:

[0007] Step 1: Prepare a zinc alloy coating on the press-fit screw;

[0008] Step 2: Connect the zinc alloy coated press-fit screws to the panel using a press-fit machine;

[0009] Step 3: Connect the press-fit screws to the panel at the riveting joint on the panel surface by welding to form a continuous metal transition from aluminum to steel.

[0010] Step 4: Grind and polish the weld seam with sandpaper;

[0011] Step 5: Perform chemical oxidation treatment on the riveted panel and then electrostatic powder coating within 24 hours;

[0012] Step 6: Use an electrostatic spray gun to evenly spray powder coating onto the surface of the workpiece;

[0013] Step 7: Heat and cure the powder coating.

[0014] Furthermore, in step 1, the rivet screws are made of stainless steel, the panel is made of 6063 aluminum, and the zinc alloy coating material is a zinc alloy containing 0.1 wt.% Ni.

[0015] Furthermore, in step 1, a zinc alloy coating is prepared by hot-dip galvanizing, electroplating, brush plating, cold spraying, or thermal spraying.

[0016] Furthermore, in step 1, a zinc alloy coating is prepared by hot-dip galvanizing.

[0017] Furthermore, in step 3, precision pulse cold welding is used for welding; 6063 aluminum welding wire with a diameter of Φ0.4mm is selected, the cold welding mode is continuous mode, the current is 30-40A, the welding time is 40-60ms, the distance between the tungsten needle and the welding wire is 0.5-1.0mm, the welding torch deflection angle is about 70°, the angle between the welding wire and the workpiece is about 15°, the argon flow rate is 10L / min, and the gas delay time is 5s.

[0018] Furthermore, in step 5, the chemical oxidation treatment should conform to the type 3 membrane specified in SJ201813-2002.

[0019] Furthermore, in step 6, an electrostatic spray gun is used for spraying, and the total air volume of the spraying equipment is set to 5 Nm³. 3 / h, set the powder output of the spraying equipment to 70%, control the distance between the spray gun nozzle and the workpiece to 150mm~200mm, the spraying speed to be about 15cm / s, and the dry film thickness of the coating should reach 50μm~130μm.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention uses welding to connect the rivet screws to the panel, forming a metallurgically bonded reinforced layer with a high degree of adhesion. This not only solves the problems of poor adhesion and low bonding strength associated with traditional conductive putty application, such as easy powdering when exposed to moisture, cracking after a certain period of time, peeling, and falling off of the conductive putty, but also repairs the annular pits at the panel riveting joints with brazing filler metal, forming a continuous metal transition from aluminum to steel. This avoids the Faraday cage effect during electrostatic powder coating and completely solves the problem of rivet marks after spraying. Attached Figure Description

[0022] Figure 1 This is a flowchart of a riveted panel preparation method proposed in this invention. Detailed Implementation

[0023] The present invention provides a method for preparing a riveted panel, which includes the following:

[0024] Step 1, Coating Preparation

[0025] The rivet screws are made of stainless steel, while the panel is made of aluminum. To protect the surface of the rivet screws from oxidation at high temperatures and to improve the wettability between the steel and aluminum, a zinc alloy coating is applied to the rivet screws at the joint with the panel. Coating preparation methods include hot-dip galvanizing, electroplating, electroplating, cold spraying, and thermal spraying.

[0026] Step 2, riveting

[0027] Zinc alloy coated rivet screws are used to connect the screws to the panel using a rivet machine.

[0028] Step 3, Composite Connection

[0029] At the riveting joint on the panel surface, the press-fit screws are connected to the panel by welding. At this time, the tiny annular pit formed by the height difference between the panel and the press-fit screw pressed into the panel will be filled with brazing filler metal, forming a continuous metal transition from aluminum to steel.

[0030] Step 4, Post-weld treatment

[0031] The weld was polished with sandpaper, and it was found to be free of porosity, stress, and cracks.

[0032] Step 5, Surface pretreatment

[0033] The riveted panels undergo chemical oxidation treatment. Following surface pretreatment, electrostatic powder coating should be applied within 24 hours.

[0034] Step 6, Coating

[0035] Electrostatic spray guns are used to spray powder coating evenly onto the surface of the workpiece.

[0036] Step 7, Curing

[0037] Powder coatings are cured by heating. The curing temperature and time are determined according to the technical parameters of the powder coating used, and the time is calculated from the moment the specified temperature is reached. For other self-contained powder coatings, curing should be performed according to the product instructions.

[0038] In an optimized manner, in step 1, the zinc alloy coating material is selected as a zinc alloy containing 0.1 wt.% Ni.

[0039] In the optimized step 1, the zinc alloy coating is preferably prepared by hot-dip galvanizing, which involves immersing the rivet joint of the press screw in molten zinc alloy at 450°C for 5 minutes.

[0040] In the optimized version of step 3, considering the impact of welding deformation and post-weld surface treatment on the panel, precision pulse cold welding is selected. Aluminum welding wire with a diameter of Φ0.4mm is used, the cold welding mode is continuous, the current is 30-40A, the welding time is 40-60ms, the distance between the tungsten needle and the welding wire is 0.5-1.0mm, the welding torch angle is approximately 70°, the angle between the welding wire and the workpiece is approximately 15°, the argon gas flow rate is 10L / min, and the gas delay time is 5s.

[0041] Ideally, in step 5, the chemical oxidation treatment should conform to the type 3 membrane specified in SJ201813-2002.

[0042] In the optimized version, step 6 sets the total air volume of the spraying equipment to 4 Nm³. 3 / h-4.8Nm 3 The powder output of the spraying equipment should be set to 20%–70% per hour. Electrostatic spraying should be used, with the distance between the spray gun nozzle and the workpiece controlled at 150mm–200mm, and the spraying speed approximately 10–15cm / s. The dry film thickness of the coating should reach 50μm–130μm.

[0043] The following reference Figure 1 A more detailed explanation of the preparation method:

[0044] Step 1, Coating Preparation

[0045] The rivet screws are made of stainless steel, while the panel is made of 6063 aluminum. To protect the surface of the rivet screws from oxidation at high temperatures and to improve the wettability between the steel and aluminum, a zinc alloy coating is applied to the rivet screws at the joint between them and the panel.

[0046] The zinc alloy coating material is selected from zinc alloys containing 0.1 wt.% Ni.

[0047] The zinc alloy coating is preferably prepared by hot-dip galvanizing, which involves immersing the rivet joint of the press-fit screw in molten zinc alloy at 450°C for 5 minutes.

[0048] Step 2, riveting

[0049] Zinc alloy coated rivet screws are used to connect the screws to the panel using a rivet machine.

[0050] Step 3, Composite Connection

[0051] At the riveting joint on the panel surface, the press-fit screws are connected to the panel by welding. At this time, the tiny annular pit formed by the height difference between the panel and the press-fit screw pressed into the panel will be filled with brazing filler metal, forming a continuous metal transition from aluminum to steel.

[0052] Considering the impact of welding deformation and post-weld surface treatment on the panel, precision pulse cold welding was selected. 6063 aluminum welding wire with a diameter of Φ0.4mm was used, with continuous cold welding mode, a current of 35A, a welding time of 50ms, a tungsten needle distance of 0.5mm from the welding wire, a welding torch angle of approximately 70°, an angle between the welding wire and the workpiece of approximately 15°, an argon gas flow rate of 10L / min, and a gas delay time of 5s.

[0053] Step 4, Post-weld treatment

[0054] The weld was polished with sandpaper, and it was found to be free of porosity, stress, and cracks.

[0055] Step 5, Surface pretreatment

[0056] The riveted panels should undergo chemical oxidation treatment. After surface pretreatment, electrostatic powder coating should be carried out within 8 hours. If the pretreatment quality is found to be substandard before coating, it should be retreated to meet the requirements.

[0057] The chemical oxidation treatment shall conform to the type 3 membrane specified in SJ201813-2002.

[0058] Step 6, Coating

[0059] Electrostatic spray guns are used to spray powder coating evenly onto the surface of the workpiece.

[0060] The total air volume of the spraying equipment is set to 4 Nm³. 3 Set the powder output of the spraying equipment to 60% per hour. Use an electrostatic spray gun, keeping the distance between the spray gun nozzle and the workpiece at 150mm, and the spraying speed at approximately 15cm / s. The dry film thickness of the coating should reach 80μm.

[0061] Step 7, Curing

[0062] Epoxy polyester powder coatings are cured by heating. The curing temperature and curing time are determined according to the technical parameters of the powder coating used. The time is calculated from the time the specified temperature is reached.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a riveted panel, characterized in that, Specifically, the following steps are included: Step 1: Prepare a zinc alloy coating on the rivet screw; the rivet screw is made of stainless steel, the faceplate is made of 6063 aluminum, and the zinc alloy coating material is a zinc alloy containing 0.1 wt.% Ni. Step 2: Connect the zinc alloy coated press-fit screws to the panel using a press-fit machine; Step 3: Connect the press-fit screws to the panel at the riveting joint on the panel surface by welding to form a continuous metal transition from aluminum to steel; use precision pulse cold welding; use 6063 aluminum welding wire with a diameter of Φ0.4mm, continuous mode for cold welding, current 30-40A, welding time 40-60ms, distance of tungsten needle from welding wire 0.5-1.0mm, welding torch deflection angle of about 70º, angle between welding wire and workpiece of about 15º, argon gas flow rate 10L / min, and gas delay time 5s; Step 4: Grind and polish the weld seam with sandpaper; Step 5: Perform chemical oxidation treatment on the riveted panel and then electrostatic powder coating within 24 hours; Step 6: Use an electrostatic spray gun to evenly spray powder coating onto the surface of the workpiece; Step 7: Heat and cure the powder coating.

2. The method for preparing a riveted panel according to claim 1, characterized in that, In step 1, zinc alloy coatings are prepared by hot-dip galvanizing, electroplating, brush plating, cold spraying, or thermal spraying.

3. The method for preparing a riveted panel according to claim 1, characterized in that, In step 1, a zinc alloy coating is prepared by hot-dip galvanizing.

4. The method for preparing a riveted panel according to claim 1, characterized in that, In step 5, the chemical oxidation treatment should conform to the type 3 membrane specified in SJ201813-2002.

5. The method for preparing a riveted panel according to claim 1, characterized in that, In step 6, an electrostatic spray gun is used for spraying, and the total air volume of the spraying equipment is set to 5 Nm³. 3 / h, set the powder output of the spraying equipment to 70%, control the distance between the spray gun nozzle and the workpiece to 150mm~200mm, the spraying speed to be about 15cm / s, and the dry film thickness of the coating should reach 50μm~130μm.

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