A method for repairing the outer surface of an oil passage of a steel pipe embedded in an aluminum-magnesium alloy casting

Abstract

The present technology belongs to the field of welding repair of magnesium and aluminum alloy castings and parts of steel pipe oil circuit outer wall casting defects, and relates to the welding repair process of magnesium and aluminum castings and parts to enhance the cooling effect and control the welding collapse and deformation. It relates to a welding repair method for the outer surface of the embedded steel pipe oil circuit of aluminum and magnesium alloy castings. By passing cooling water into the steel pipe oil circuit during welding and using auxiliary equipment to control the water temperature, the overheat and collapse of the steel pipe surface during welding are avoided. The purpose of the present invention is to control the temperature of the steel pipe during welding repair by designing a temperature control system to avoid the collapse of the steel pipe due to overheating.

Description

Technical Field

[0001] This invention pertains to the field of welding repair of casting defects on the outer wall of oil passages in magnesium and aluminum alloy castings and parts for aerospace applications. It relates to enhancing cooling effects and controlling weld collapse and deformation during the welding repair process of magnesium and aluminum castings and parts for aerospace applications. Specifically, it relates to a method for welding repair of the outer surface of oil passages in pre-embedded steel pipes in aluminum and magnesium alloy castings. Background Technology

[0002] Magnesium and aluminum alloys, with their high specific strength and low density, are widely used in the manufacture of aerospace parts. Most aluminum and magnesium alloy aerospace castings have complex structures, with some areas using steel pipes as internal oil passages, offering advantages such as structural stability and strong oil pressure resistance. However, due to the significant differences in the coefficients of thermal expansion and thermal conductivity between steel and aluminum / magnesium, defects such as porosity and linear cracks are easily generated in the aluminum and magnesium casting matrix during the casting process. Manual argon arc welding is generally used for repair, but this method involves high heat input and can easily cause the steel pipe oil passages to collapse and become blocked, leading to the scrapping of the casting and resulting in losses. Summary of the Invention

[0003] Purpose of the invention

[0004] By employing enhanced cooling, heat input during the argon arc welding repair process can be effectively controlled, preventing the collapse of the steel pipe oil circuit. This invention primarily addresses the problem of heat input control during the welding repair process of oil circuits in magnesium and aluminum alloy castings after defects are discovered, avoiding the collapse and blockage of the oil circuit during welding. This invention prevents overheating and collapse of the steel pipe surface during welding by introducing cooling water into the oil circuit during welding and using auxiliary equipment to control the water temperature. The purpose of this invention is to control the temperature of the steel pipe during welding repair through a designed temperature control system, preventing collapse due to overheating.

[0005] Technical solution

[0006] A method for welding and repairing the outer surface of pre-embedded steel pipe oil circuits in aluminum and magnesium alloy castings. This invention relates to cast aluminum alloys and cast magnesium alloys, and the defect morphology of the castings is shown in the figure. Figure 1 As shown, the defects to be repaired are usually loose, cracks, etc., and the repair size is about 15mm*15mm, with a thickness of about 6mm (leaving a 1mm allowance).

[0007] The purpose of this invention is to provide a method for welding and repairing the outer surface of oil circuits embedded in aluminum and magnesium alloy castings, comprising the following steps:

[0008] Step 1: Evaluate the surface quality of the welded repair area using X-ray diffraction and fluorescence penetrant testing to verify whether the repair process meets the casting quality requirements;

[0009] Step 2: Inspect the oil circuit of the pre-embedded steel pipe in the casting through X-ray diffraction and fluorescence penetrant testing to find surface and internal defects. Remove the defects by grinding and clean the surface of the area to be repaired with acetone or alcohol.

[0010] Step 3: Use a steel brush or sandpaper to polish and remove the oxide film from the surface of the wire used for repair, and then use manual argon arc welding to perform the repair.

[0011] Step 4: Use dimensional inspection tools to measure the dimensions of the repaired area to ensure that the thickness meets the design requirements;

[0012] Step 5: Inspect the repaired area using X-ray diffraction and fluorescence penetrant testing, ensuring there are no cracks or defects.

[0013] Preferably, the test specimens required for repair in step one are obtained from actual repair specimens to obtain an assessment of the actual repair quality.

[0014] Preferably, the wire used for repair is an aluminum-magnesium alloy welding wire with a diameter of 2-6 mm, and its composition should be the same as that of the material being welded and repaired.

[0015] Preferably, the manual argon arc welding repair process parameters in step three are: current 90-200A, argon gas as shielding gas, argon gas flow rate 15L / min-20L / min, arc extension 5mm-10mm, and cleaning width 5mm-12mm.

[0016] Preferably, in step three, the pre-embedded steel pipe oil circuit to be repaired should be connected to a temperature control system, and the internal temperature of the steel should be controlled within 90°C.

[0017] Preferably, the manual argon arc welding repair strategy in step three involves using a vernier caliper to inspect the dimensions of the area to be repaired, and reshaping the area to be repaired according to the characteristic shape of the repair location on the casting to meet the required dimensional standards of the casting.

[0018] The beneficial effects of this application are as follows:

[0019] 1. This invention, through welding repair of the temperature control system, can avoid secondary defects such as collapse and penetration of the pre-embedded steel pipe during the repair process, thus avoiding affecting the repair quality.

[0020] 2. The present invention, through a welding repair temperature control system, can avoid deformation and stress concentration of castings and embedded steel pipes caused by large heat input during the repair process. The welding repair temperature control system can effectively remove the high heat input during the repair process and perform feedback control based on the temperature inside the steel pipe.

[0021] 3. This invention is a rapid response system with a quick connector, which is simple and convenient to operate, has a wide range of applications, requires little post-processing and has low cost, making it easy to promote and apply. Attached Figure Description

[0022] Figure 1 Diagram of the repaired steel pipe oil circuit;

[0023] Figure 2 This is an X-ray examination image;

[0024] Figure 3 Fluorescence test chart;

[0025] Figure 4 Schematic diagram of welding temperature control system;

[0026] Figure 5 Schematic diagram of sensor distribution inside the steel pipe. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments. The following description represents only a portion of the embodiments of the present invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0028] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. The specific implementation process steps are as follows:

[0029] 1. Select the appropriate repair wire material based on the material to be repaired and verify the feasibility of the process. Taking ZM6 as an example, the chemical composition weight percentage of ZM6 is as follows: Zn 0.2%–0.7%, Zr 0.4%–1.0%, Nd 2.0%–2.8%, with magnesium as the balance. When repairing the embedded steel pipe of ZM6 castings, the chemical composition weight percentage of the selected welding wire material should be: Zn 0.2%–0.7%, Zr 0.4%–1.0%, and Nd 2.0%–2.8%. The diameter of the repair wire should be 2mm–6mm. Use a steel brush or sandpaper to grind the surface of the welding wire clean, and then clean it with alcohol or acetone.

[0030] 2. X-ray and fluorescence methods were used to inspect the surface and cross-section of the welded repair area. The repair quality of the casting was evaluated based on defects in the magnesium alloy body near the embedded steel pipe to obtain a repair process that meets the casting's service standards. (See...) Figure 2 , 3 .

[0031] 3. The repaired area has a well-formed surface with a metallic luster. The dimensions of the steel pipe are unaffected by the repair, and the repaired magnesium alloy body is free of secondary defects such as cracks, porosity, and pores (>2mm). The steel pipe and magnesium alloy body are tightly bonded at the repair location, with no obvious gaps. The repair process meets the quality requirements for the repair of embedded steel pipes in aluminum and magnesium alloy castings. See [link / details]. Figure 2 and Figure 3 .

[0032] 4. After the process is determined, use fluorescence detection and X-ray detection to inspect the oil circuit of the pre-embedded steel pipe in the casting, locate the defects, remove the defects with cleaning and grinding tools, and then clean the surface with acetone or alcohol.

[0033] 5. Clean the surface oxide film layer of the wire used for repair with a steel brush or sandpaper, and clean it with acetone or alcohol; connect the casting to be repaired to the welding temperature control system, so that the inside of the steel pipe is filled with cooling circulating coolant; the welding temperature control system can control the internal temperature of the steel pipe, such as... Figure 4 As shown.

[0034] 6. The welding temperature control system consists of a temperature sensor system inside the steel pipe, a coolant circulation pump system, and a CNC system. The temperature sensor inside the steel pipe can be used to test the water temperature, and the coolant circulation flow rate is adjusted based on the water temperature feedback to maintain the water temperature below 90℃. Figure 4 As shown.

[0035] 7. The specific working mode of the welding temperature control system is as follows: Coolant tank 1 is used to store circulating coolant. A coolant circulation system is formed by water pump 14 through inlet 13, outlet 12, pipe 1, pipe 3, connector 16, connector 17, and pre-embedded steel pipe 5. Coolant is drawn from coolant tank 1 by water pump 14, passes through pipe 3, water pump 14, outlet 12, pre-embedded steel pipe 5, and pipe 2 in sequence, and then flows back into coolant tank 1. During the coolant circulation process, temperature sensors 6 and 7 measure the internal temperature of the steel pipe, and the measured temperature is converted into an electrical signal by signal converters 9 and 8 and transmitted to the CNC system 15. Figure 5 The CNC system 15 adjusts the speed of the water pump 14 according to the measured temperature, thereby achieving the purpose of temperature regulation.

[0036] 8. During the repair process, maintain an angle of 75°–80° between the welding torch and the horizontal plane of the molten pool, and an angle of 15°–30° between the welding wire and the plane of the molten pool. Use a shielding gas flow rate of 15L / min–20L / min, a welding current of 90A–200A, an arc extension of 5mm–10mm, and a cleaning width of 5mm–12mm. Ensure the arc is on the magnesium alloy molten pool during the repair process, guaranteeing full molten pool spread and eliminating any incomplete fusion or undercut. A schematic diagram of the welding repair is shown below. Figure 2 ,3 As shown.

[0037] 9. After repair, the surface is flat and shiny. Use calipers to measure the local dimensions after repair, and use cleaning and polishing tools to remove excess dimensions, leaving a 2mm allowance.

[0038] 10. X-ray and fluorescent flaw detection were performed on the repaired area of ​​the casting, and no defects were found on the surface or inside.

[0039] Technical advantages: Compared with existing technologies, the technical solution of this invention repairs defects near embedded steel pipes in aluminum alloy and magnesium alloy castings, ensuring no deformation or collapse at the steel pipe location, and eliminating secondary defects such as cracks and porosity (>2mm) on the internal and surface of the repaired component, while meeting the dimensional standards for casting use. Furthermore, the process is simple, saving castings from scrap. It is currently being used in actual casting production.

[0040] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless defined as herein. The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for welding and repairing the outer surface of oil circuits embedded in aluminum or magnesium alloy castings, characterized in that, Includes the following steps: Step 1: Evaluate the surface quality of the welded repair area using X-ray diffraction and fluorescence penetrant testing to verify whether the repair process meets the casting quality requirements; Step 2: Inspect the oil circuit of the pre-embedded steel pipe in the casting through X-ray diffraction and fluorescence penetrant testing to find surface and internal defects. Remove the defects by grinding and clean the surface of the area to be repaired with acetone or alcohol. Step 3: Use a steel brush or sandpaper to polish and remove the oxide film from the surface of the wire used for repair. Simultaneously, perform manual argon arc welding for repair. The oil circuit of the embedded steel pipe to be repaired in Step 3 should be connected to a temperature control system, and the internal temperature of the embedded steel pipe should be controlled below 90℃. The manual argon arc welding repair process parameters are: current 90~200A, argon gas as shielding gas; argon gas flow rate 15L / min~20L / min, arc extension 5mm~10mm, cleaning width 5mm~12mm; the wire used for repair is aluminum or magnesium alloy welding wire, and its composition should be the same as the material being welded and repaired; the diameter of the aluminum or magnesium alloy welding wire is 2mm~6mm. Step 4: Use dimensional inspection tools to measure the dimensions of the repaired area to ensure that the thickness meets the design requirements; Step 5: Inspect the repaired area using X-ray diffraction and fluorescence penetrant testing, ensuring there are no cracks or defects. The specific operating mode of the temperature control system is as follows: The coolant tank is used to store circulating coolant. A coolant circulation system is formed by a water pump through the inlet, outlet, pipe A, pipe B, connector A, connector B, and pre-embedded steel pipe. The coolant is drawn from the coolant tank by the water pump, passes through pipe B, the water pump, the outlet, the pre-embedded steel pipe, and pipe A in sequence, and then flows back into the coolant tank. During the coolant circulation process, temperature sensors A and B measure the internal temperature of the steel pipe and convert the measured temperature into an electrical signal through signal converters A and B, which is then transmitted to the CNC system. The CNC system adjusts the speed of the water pump according to the measured temperature to achieve the purpose of temperature regulation.

2. The method of claim 1, wherein, The required repair samples in step one are obtained from actual repair samples to obtain an assessment of the actual repair quality.

3. The method of claim 1, wherein, The manual argon arc welding repair strategy in step three involves using a vernier caliper to inspect the dimensions of the area to be repaired, and reshaping the area to be repaired according to the characteristic shape of the repair location on the casting to meet the required dimensional standards of the casting.

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