Maintenance and remanufacturing device and method for prolonging service life of lock slag valve

Abstract

The invention belongs to the technical field of valve remanufacturing, and discloses a maintenance and remanufacturing method for prolonging the service life of a lock slag valve, which comprises the following steps: carrying out surface pretreatment on the sealing surfaces of a valve ball and a valve seat; planning and optimizing a spray welding platform coating preparation path through finite element simulation modeling; performing multi-pass composite coating preparation on the sealing surfaces of the valve ball and the valve seat through the spray welding platform according to the coating preparation path; the sealing surfaces of the valve ball and the valve seat are precisely machined through a numerical control lathe and a grinding machine; a diamond-like coating is deposited on the sealing surface of the valve ball and the valve seat through a diamond-like coating preparation process; and carrying out alloy treatment and clearance control on friction surfaces of the wear-resistant sleeves of the valve ball and the valve rod. The thickness uniformity and consistency of a spray welding layer are achieved, the problem that the hardness deviation of a machined finished product on the same spherical surface is large due to the fact that the thickness of the alloy spray welding layer is not uniform due to traditional thermal spraying is solved, and the phenomena that stripping, shelling and the like are likely to happen due to the stress problem caused by the non-uniform thickness are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of valve remanufacturing, and in particular to a repair and remanufacturing device and method for increasing the service life of a slag lock valve. Background Art

[0002] Under high pressure, high temperature and medium (coal slag) with very high hardness, the slag lock valve opens and closes frequently and at high speeds, which places very high demands on the valve's sealing performance and reliability. Traditional slag lock valves have a short online operation cycle and large downtime losses. The main manifestations are: gradient wear of the sealing surface: Due to the physical bonding characteristics of traditional supersonic sprayed WC coatings, they are prone to layered peeling under thermal shock conditions. For example, statistics from a certain factory show that coating peeling causes more than 60% of unplanned downtime; thermal distortion of the ball-stem system. The current horizontal spray welding process causes the ball-stem assembly to have a coaxial deviation of >0.15mm / 300mm; the friction pair is cold-welded and locked. Under a radial load of >20kN, the 17-4PH / Stellite6 friction pair between the valve stem locating sleeve and the ball stem produces microscopic diffusion welding.

[0003] In the existing technology, the above problems are often solved by laser cladding technology, traditional thermal spraying technology and supersonic tungsten carbide spraying technology.

[0004] However, laser cladding technology: Although it can achieve 0.1mm coating uniformity, during the laser cladding process, the laser beam heats the material to a molten state in a very short time, and then quickly cools it. This rapid heating and cooling process will lead to local thermal stress concentration. The thermal expansion coefficients of the base material and the cladding layer are different, and they shrink inconsistently during cooling, generating tensile stress. When the tensile stress exceeds the tensile strength of the material, cracks will form. The cracks will reduce the bonding strength of the coating and the overall performance of the valve ball. Especially in high stress or corrosive environments, the cracks may expand, causing the coating to peel off or fail.

[0005] Traditional thermal spray welding process: The uneven thickness of the alloy spray welding layer leads to large hardness deviation of the finished product on the same spherical surface after processing, the uneven thickness of the alloy layer causes stress problems, and peeling and shelling phenomena; for the valve ball spray welding method with integrated ball and rod, most of the current methods use oxyacetylene thermal spray welding. The common heating method is horizontal heating. The valve stem is used as the rotating axis at one end, and the welding extension shaft is used as the rotating axis at the other end. Regardless of whether well-type electric furnace heating or oxyacetylene or oxypropane heating is used, the valve stem and the welding extension shaft will be heated at the same time. Under the action of the gravity of the valve ball, thermal deformation or thermal stress between the ball and rod is inevitable; in the current method, since powder spraying must avoid spraying powder onto the heating body to cause short circuit and other problems, the powder spraying and remelting stations are separated from the heating station. During transportation, it is easy to cause rapid temperature changes that affect the adhesion of the alloy powder layer and seriously affect the spray welding quality.

[0006] Supersonic spraying tungsten carbide process: The advantage is that the hardness can reach HRC68 or above, which seems to solve the hardness problem. However, due to the physical bonding rather than metallurgical bonding of supersonic spraying, the thickness of the sprayed layer is ≤0.3, the bonding strength is low, and the thin thickness of the sprayed layer can easily cause the coating to peel off under high pressure or impact load.

[0007] In summary, the existing methods still have problems such as uneven thickness of the alloy spray-welded layer, which leads to large hardness deviation on the same spherical surface of the processed finished product, uneven thickness of the alloy layer causing stress problems, and peeling and shelling phenomena; the one-piece ball rod has concentricity problems due to thermal deformation or thermal stress during the spray-welding process; and the valve stem and the fixed ball positioning sleeve have a cold welding phenomenon due to the friction under weight, which causes a jamming problem. Summary of the Invention

[0008] The object of the present invention is to provide a maintenance and remanufacturing device and method for increasing the service life of a slag lock valve, so as to solve the problems raised in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A maintenance and remanufacturing method for increasing the service life of a slag lock valve comprises the following steps:

[0011] Step 1: Pre-treat the sealing surfaces of the valve ball and valve seat;

[0012] Step 2: Plan and optimize the coating preparation path of the spray welding platform through finite element simulation modeling;

[0013] Step 3: Prepare multiple composite coatings on the sealing surfaces of the valve ball and valve seat using a spray welding platform according to the coating preparation path;

[0014] Step 4: Use CNC lathes and grinders to precisely machine the sealing surfaces of the valve ball and valve seat;

[0015] Step 5: depositing a diamond-like coating on the sealing surfaces of the valve ball and the valve seat using a diamond-like coating preparation process;

[0016] Step 6: Alloy treatment and clearance control of the friction surface of the wear-resistant sleeve of the valve ball and valve stem.

[0017] Further preferably, in step 1, the sealing surfaces of the valve ball and the valve seat are subjected to surface pretreatment, including removing the old coating, surface cleaning and roughening treatment in sequence. After the surface pretreatment is completed, the surface roughness Ra of the sealing surfaces of the valve ball and the valve seat is 3.2-6.3 μm.

[0018] Further preferably, in the step 2, when planning and optimizing the coating preparation path of the spray welding platform through finite element simulation modeling, a temperature field-stress field coupling model is established through ANSYS software to simulate the thermal deformation trend of the valve ball and valve seat during the spray welding process of the spray welding platform, and the spray welding path of the spray welding platform is optimized to be spiral progressive; at the same time, the thermal deformation of the valve ball and valve seat is monitored in real time by a laser micrometer.

[0019] Further preferably, in the step 3, when the sealing surfaces of the valve ball and the valve seat are subjected to multiple passes of composite coating preparation according to the coating preparation path through the spray welding platform, the composite coating preparation is completed in multiple passes along the weft direction of the valve ball and the valve seat, with an overlap rate of 30% for each pass and a total composite coating thickness of 1.2-1.5 mm; after the composite coating preparation of the sealing surfaces of the valve ball and the valve seat is completed, a slow cooling treatment is performed; the spray welding powder is a nickel-based alloy with a particle size of 45-75 μm.

[0020] Further preferably, in step 4, when the sealing surfaces of the valve ball and the valve seat are precision-machined by a CNC lathe and a grinder, the sealing surfaces of the valve ball and the valve seat are turned and ground by a CNC lathe and a grinder in turn to ensure that the surface roughness of the sealing surfaces of the final valve ball and the valve seat is Ra≤0.4μm.

[0021] Further preferably, in step 5, when the diamond-like coating is deposited on the sealing surfaces of the valve ball and the valve seat by a diamond-like coating preparation process, a diamond-like coating with a thickness of 2-5 μm is deposited on the sealing surfaces of the valve ball and the valve seat by the diamond-like coating preparation process; and before the deposition by the diamond-like coating preparation process, a Cr transition layer with a thickness of 50-100 nm is set between the composite coating and the diamond-like coating, and XRD detection confirms that a Cr3C2 gradient phase is formed; the nanoindentation hardness of the diamond-like coating is HIT=85±5 GPa, and the elastic modulus E=450±50 GPa.

[0022] Further preferably, in step 6, when alloying the friction surfaces of the wear-resistant sleeves of the valve ball and the valve stem, the front and rear wear-resistant sleeves are made of HV750 grade Stellite 12 alloy, and the front and rear valve stems are made of HV550 grade Stellite 6 alloy, forming a hardness gradient ΔHV ≥ 200; when performing clearance control on the friction surfaces of the wear-resistant sleeves of the valve ball and the valve stem, a hydraulic expansion tool is used to adjust the fitting clearance of the wear-resistant sleeves of the valve ball and the valve stem to 0.08-0.12 mm, and the rotation centers of the valve ball and the valve stem are on the same center line.

[0023] The present invention also provides a technical solution, a maintenance and remanufacturing device for improving the service life of a slag lock valve, comprising a workbench, wherein the surface of the workbench is symmetrically and slidingly connected to an electric furnace, a clamp is provided at the center between the two electric furnaces, a valve stem and a valve ball are clamped on the clamp, the bottom of the clamp passes through the surface of the workbench and is connected to a first transmission gear, a second transmission gear is meshed with the outer side of the first transmission gear, the second transmission gear is connected to the driving end of a servo motor through a transmission shaft, and a spray welding robot is also provided on one side of the workbench.

[0024] Further preferably, guide rails are symmetrically arranged on the surface of the workbench, a mounting plate is provided at the bottom of each of the two electric furnaces, sliders are provided at the four corners of the bottom of the mounting plate, and the sliders are slidably connected to the guide rails.

[0025] Further preferably, a plurality of bearing seats are provided on one side of the bottom of the workbench close to the transmission shaft, and the transmission shaft is rotatably connected to the inside of the bearing seats.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] A temperature field-stress field coupling model was established using ANSYS software to simulate the thermal deformation trend of the valve ball and valve seat during the spray welding process. The platform's spray welding path was optimized to a spiral progressive pattern. A laser micrometer was used to monitor the thermal deformation of the valve ball and valve seat in real time. The spray welding platform applied multiple passes of composite coating to the sealing surfaces of the valve ball and valve seat according to the coating preparation path. The composite coating was completed in multiple passes along the weft of the valve ball and valve seat, with a 30% overlap rate per pass and a total composite coating thickness of 1.2-1.5mm. After the composite coating on the sealing surfaces of the valve ball and valve seat was completed, a slow cooling treatment was performed. This approach solves the problem of uniform and consistent thickness of the sprayed layer, ensuring the uneven thickness of the alloy sprayed layer caused by traditional thermal spraying, which leads to large hardness deviations on the same spherical surface of the finished product. This also avoids stress problems caused by uneven thickness that can easily lead to peeling and debonding. On this basis, the carbide sealing surfaces formed by spray welding on the sealing surfaces of the valve ball and valve seat are precisely processed using CNC lathes and CNC grinders, and then a 2-5μm thick diamond-like coating is deposited on the sealing surfaces of the valve ball and valve seat using a diamond-like coating preparation process. Before deposition using the diamond-like coating preparation process, a 50-100nm thick Cr transition layer is set between the composite coating and the diamond-like coating, which increases the interlayer bonding strength between the composite coating and the diamond-like coating by 40%, enhances resistance to medium erosion, reduces friction resistance on the ball seat sealing surface, and reduces the cylinder drive torque.

[0028] When alloying the friction surfaces of the wear sleeves of the valve ball and valve stem, the front and rear wear sleeves are made of HV750-grade Stellite 12 alloy, and the front and rear valve stems are made of HV550-grade Stellite 6 alloy, forming a hardness gradient ΔHV ≥ 200 to avoid cold welding under friction conditions that may cause the valve stem and wear sleeve to be stuck. When performing clearance control on the friction surfaces of the wear sleeves of the valve ball and valve stem, a hydraulic expansion tool is used to adjust the fitting clearance of the wear sleeves of the valve ball and valve stem to 0.08-0.12mm, and the rotation centers of the valve ball and valve stem are on the same center line, eliminating the radial displacement of the valve ball under pressure due to improper clearance, which transmits pressure to the rear valve seat and squeezes the spring of the valve seat, causing damage or failure of the spring, directly affecting the online operation life of the valve. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic structural diagram of the spray welding platform of the present invention;

[0030] Figure 2 A schematic diagram comparing the bonding strength of the coating of the present invention and the bonding strength of the coating prepared by the transmission method;

[0031] Figure 3 Schematic diagram comparing the hardness of the coating of the present invention and the hardness of the coating prepared by the transmission method;

[0032] Figure 4 This is a schematic diagram comparing the online operating life of the slag lock valve of the present invention;

[0033] In the figure: 1. Electric furnace; 2. Workbench; 3. Spray welding robot; 4. First transmission gear; 5. Second transmission gear; 6. Transmission shaft; 7. Servo motor; 8. Slider; 9. Guide rail; 10. Clamp; 11. Valve ball; 12. Valve stem. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] See also Figure 1-4 , the present invention provides a technical solution:

[0036] A maintenance and remanufacturing method for increasing the service life of a slag lock valve comprises the following steps:

[0037] Step 1: Pre-treat the sealing surfaces of the valve ball 11 and the valve seat;

[0038] Step 2: Plan and optimize the coating preparation path of the spray welding platform through finite element simulation modeling;

[0039] Step 3: Perform multiple passes of composite coating on the sealing surfaces of the valve ball 11 and the valve seat according to the coating preparation path using a spray welding platform;

[0040] Step 4: Precision machining the sealing surfaces of the valve ball 11 and the valve seat using a CNC lathe and a grinder;

[0041] Step 5: depositing a diamond-like coating on the sealing surfaces of the valve ball 11 and the valve seat using a diamond-like coating preparation process;

[0042] Step 6: alloy treatment and clearance control of the friction surfaces of the wear-resistant sleeves of the valve ball 11 and the valve stem 12.

[0043] In the present invention, in step 1, the sealing surfaces of the valve ball 11 and the valve seat are subjected to surface pretreatment, including removing the old coating, surface cleaning and roughening treatment in sequence. After the surface pretreatment is completed, the surface roughness Ra of the sealing surfaces of the valve ball 11 and the valve seat is 3.2-6.3μm.

[0044] In the present invention, in step 2, when planning and optimizing the coating preparation path of the spray welding platform through finite element simulation modeling, a temperature field-stress field coupling model is established through ANSYS software to simulate the thermal deformation trend of the valve ball 11 and the valve seat during the spray welding process of the spray welding platform, and the spray welding path of the spray welding platform is optimized to be spiral progressive; at the same time, the thermal deformation of the valve ball 11 and the valve seat is monitored in real time by a laser micrometer.

[0045] In the present invention, in step 3, when the sealing surfaces of the valve ball 11 and the valve seat are subjected to multiple passes of composite coating preparation according to the coating preparation path through the spray welding platform, the composite coating preparation is completed in multiple passes along the weft direction of the valve ball 11 and the valve seat, with an overlap rate of 30% for each pass and a total composite coating thickness of 1.2-1.5 mm; after the composite coating preparation of the sealing surfaces of the valve ball 11 and the valve seat is completed, a slow cooling treatment is performed; the spray welding powder is a nickel-based alloy with a particle size of 45-75 μm.

[0046] In the present invention, in step 4, when the sealing surfaces of the valve ball 11 and the valve seat are precisely processed by a CNC lathe and a grinder, the sealing surfaces of the valve ball 11 and the valve seat are turned and ground by a CNC lathe and a grinder in turn to ensure that the surface roughness of the sealing surfaces of the final valve ball 11 and the valve seat is Ra≤0.4μm.

[0047] In the present invention, in step 5, when the diamond-like coating is deposited on the sealing surface of the valve ball 11 and the valve seat by the diamond-like coating preparation process, a diamond-like coating with a thickness of 2-5 μm is deposited on the sealing surface of the valve ball 11 and the valve seat by the diamond-like coating preparation process; and before the deposition by the diamond-like coating preparation process, a Cr transition layer with a thickness of 50-100 nm is set between the composite coating and the diamond-like coating, and XRD detection confirms that a Cr3C2 gradient phase is formed; the nanoindentation hardness HIT of the diamond-like coating is 85±5 GPa, and the elastic modulus E is 450±50 GPa.

[0048] In the present invention, in step 6, when alloying the friction surfaces of the wear-resistant sleeves of the valve ball 11 and the valve stem 12, the front and rear wear-resistant sleeves are made of HV750 grade Stellite 12 alloy, and the front and rear valve stems 12 are made of HV550 grade Stellite 6 alloy, forming a hardness gradient ΔHV ≥ 200; when performing clearance control on the friction surfaces of the wear-resistant sleeves of the valve ball 11 and the valve stem 12, a hydraulic expansion tool is used to adjust the fitting clearance of the wear-resistant sleeves of the valve ball 11 and the valve stem 12 to 0.08-0.12 mm, and the rotation centers of the valve ball 11 and the valve stem 12 are on the same center line.

[0049] The present invention also provides a technical solution, a maintenance and remanufacturing device for improving the service life of a slag lock valve, comprising a workbench 2, an electric furnace 1 symmetrically and slidingly connected to the surface of the workbench 2, a clamp 10 provided at the center between the two electric furnaces 1, a valve stem 12 and a valve ball 111 clamped on the clamp 10, the bottom of the clamp 10 passes through the surface of the workbench 2 and is connected to a first transmission gear 4, a second transmission gear 5 is meshed with the outer side of the first transmission gear 4, the second transmission gear 5 is connected to the driving end of the servo motor 7 through a transmission shaft 6, and a spray welding robot 3 is also provided on one side of the workbench 2.

[0050] In the present invention, guide rails 9 are symmetrically provided on the surface of the workbench 2 , mounting plates are provided at the bottom of the two electric furnaces 1 , and sliders 8 are provided at the four corners of the bottom of the mounting plates, which are slidably connected to the guide rails 9 .

[0051] In the present invention, a plurality of bearing seats are further provided on one side of the bottom of the workbench 2 close to the transmission shaft 6, and the transmission shaft 6 is rotatably connected to the inside of the bearing seats.

[0052] Example: Take a DN400 slag lock valve of a coal chemical industry as an example.

[0053] The sealing surfaces of the valve ball 11 and the valve seat are subjected to surface pretreatment; the old coating is removed, the surface is cleaned and roughened in sequence to ensure that the surface is free of oil, oxides and other impurities. After the surface pretreatment is completed, the surface roughness Ra of the sealing surfaces of the valve ball 11 and the valve seat is 3.2-6.3μm, so as to improve the bonding strength of the subsequent composite coating.

[0054] Finite element simulation modeling was used to plan and optimize the coating preparation path for the spray welding platform. A temperature-stress field coupling model was established using ANSYS software to simulate the thermal deformation trends of the valve ball 11 and valve seat during the spray welding process. The optimized spray welding path was a spiral progressive pattern with a pitch of 8mm / turn to avoid localized heat concentration. A laser micrometer with a resolution of 0.001mm was used to monitor the thermal deformation ΔD of the valve ball 11 in real time. Based on this ΔD data, the spray welding power was dynamically adjusted by ±5%, the spray distance by ±10mm, and the robot's motion trajectory to ensure thermally induced coaxiality deviation of ≤0.03mm / 300mm.

[0055] The sealing surfaces of the valve ball 11 and the valve seat are subjected to a multi-pass composite coating preparation through a spray welding platform according to the coating preparation path; the valve ball 11 and the valve stem 12 are clamped on the fixture 10, and the valve ball 11 and the valve stem 12 are heated by an electric furnace 1. The preheating temperature of the electric furnace 1 is 650±10°C. The electric furnace 1 adopts PID closed-loop temperature control. The electric furnace 1 is an openable and closable annular partitioned heater as a whole, with 6 independent temperature zones and a temperature control accuracy of ±15°C. Each independent temperature zone is fed back by infrared temperature measurement, and the fixture 10 is driven to rotate by the servo motor 7 under the action of the transmission shaft 6, the second transmission gear 5 and the first transmission gear 4 , thereby driving the valve ball 11 and valve stem 12 to rotate. Simultaneously, the spray welding operation is performed on the valve ball 11 and valve stem 12 in conjunction with the spray welding robot 3. The spray welding robot 3 is a six-axis industrial robot with a repeatability accuracy of ±0.05mm. Its spray welding end is equipped with an oxyacetylene spray gun. The spray welding powder is a nickel-based alloy, specifically NiCrBSi alloy powder, with a particle size of 45-75μm. The spray welding robot 3 sprays at a speed of 0.8m / min, a spray distance of 120mm, and an angle of 85°. The powder feed rate is 50g / min, and the argon shielding gas flow rate is 15L / min. The composite coating is applied in multiple passes along the weft direction of the valve ball 11 and valve seat, with an overlap ratio of 30% per pass and a total composite coating thickness of 1.2-1.5mm. After the composite coating is applied to the sealing surfaces of the valve ball 11 and valve seat, a slow cooling treatment is performed at a cooling rate of ≤10°C / min to reduce residual stress.

[0056] The sealing surfaces of the valve ball 11 and the valve seat are precisely machined by a CNC lathe and a grinder; the sealing surfaces of the valve ball 11 and the valve seat are turned and ground by a CNC lathe and a grinder in turn to ensure that the surface roughness of the sealing surfaces of the valve ball 11 and the valve seat is Ra≤0.4μm.

[0057] A diamond-like coating is deposited on the sealing surface of the valve ball 11 and the valve seat through a diamond-like coating preparation process; a diamond-like coating with a thickness of 2-5 μm is deposited on the sealing surface of the valve ball 11 and the valve seat through the diamond-like coating preparation process; and before deposition through the diamond-like coating preparation process, a 50-100 nm thick Cr transition layer is set between the composite coating and the diamond-like coating. XRD detection confirms that a Cr3C2 gradient phase is formed to improve the interlayer bonding strength by 40%; the nanoindentation hardness HIT of the diamond-like coating is 85±5 GPa, and the elastic modulus E is 450±50 GPa.

[0058] The wear sleeve friction surfaces of the valve ball 11 and valve stem 12 are alloyed and clearance controlled. The front and rear wear sleeves are alloyed with HV750-grade Stellite 12 alloy, while the front and rear stems are alloyed with HV550-grade Stellite 6 alloy, creating a hardness gradient of ΔHV ≥ 200 to prevent cold welding under friction conditions. A hydraulic expansion tool is used to adjust the clearance between the wear sleeves of the valve ball 11 and valve stem 12 to 0.08-0.12mm, with the rotational centers of the valve ball 11 and valve stem 12 aligned. During the adjustment process, a laser micrometer is used to monitor the clearance changes in real time to ensure uniformity. This prevents radial displacement of the valve ball 11 under pressure due to improper clearance, which transmits pressure to the rear valve seat and compresses the spring, causing damage or failure, directly impacting the valve's service life.

[0059] Verification results:

[0060] The online operation cycle was extended from the original 6 months to 12 months, an increase of 200%; the opening and closing torque was reduced from the original valve's 850N·m to 520N·m, a decrease of 38.8%; after 3,000 opening and closing tests, the sealing surface wear was ≤0.02mm.

[0061] In summary, the method of the present invention can significantly increase the online operating life of the slag lock valve, making it more than twice the life of the original valve.

[0062] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description. It is intended that all variations within the meaning and range of equivalents of the claims be embraced herein, and any reference signs in the claims should not be construed as limiting the claims to which they relate.

[0063] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A maintenance and remanufacturing method for increasing the service life of a slag lock valve, characterized in that: The following steps are involved: Step 1: Pre-treat the sealing surfaces of the valve ball and valve seat; Step 2: Plan and optimize the coating preparation path of the spray welding platform through finite element simulation modeling; Step 3: Prepare multiple composite coatings on the sealing surfaces of the valve ball and valve seat using a spray welding platform according to the coating preparation path; Step 4: Use CNC lathes and grinders to precisely machine the sealing surfaces of the valve ball and valve seat; Step 5: depositing a diamond-like coating on the sealing surfaces of the valve ball and the valve seat using a diamond-like coating preparation process; Step 6: Alloy treatment and clearance control of the friction surface of the wear-resistant sleeve of the valve ball and valve stem.

2. A repair and remanufacturing method for increasing the service life of a slag lock valve according to claim 1, characterized in that: In step 1, the sealing surfaces of the valve ball and the valve seat are subjected to surface pretreatment, including removing old coatings, surface cleaning and roughening treatment in sequence. After the surface pretreatment is completed, the surface roughness Ra of the sealing surfaces of the valve ball and the valve seat is 3.2-6.3 μm.

3. The repair and remanufacturing method for increasing the service life of a slag lock valve according to claim 1, characterized in that: In step 2, when planning and optimizing the coating preparation path of the spray welding platform through finite element simulation modeling, a temperature field-stress field coupling model is established through ANSYS software to simulate the thermal deformation trend of the valve ball and valve seat during the spray welding process of the spray welding platform, and the spray welding path of the spray welding platform is optimized to be spiral progressive; at the same time, the thermal deformation of the valve ball and valve seat is monitored in real time by a laser micrometer.

4. The repair and remanufacturing method for increasing the service life of a slag lock valve according to claim 1, characterized in that: In step 3, when the sealing surfaces of the valve ball and the valve seat are subjected to multiple passes of composite coating preparation according to the coating preparation path through the spray welding platform, the composite coating preparation is completed in multiple passes along the latitude direction of the valve ball and the valve seat, with an overlap rate of 30% for each pass and a total composite coating thickness of 1.2-1.5 mm; after the composite coating preparation of the sealing surfaces of the valve ball and the valve seat is completed, a slow cooling treatment is performed; the spray welding powder is a nickel-based alloy with a particle size of 45-75 μm.

5. The repair and remanufacturing method for increasing the service life of a slag lock valve according to claim 1, characterized in that: In step 4, when the sealing surfaces of the valve ball and the valve seat are precisely processed by a CNC lathe and a grinder, the sealing surfaces of the valve ball and the valve seat are turned and ground by the CNC lathe and the grinder in turn to ensure that the surface roughness of the sealing surfaces of the final valve ball and the valve seat is Ra≤0.4μm.

6. The repair and remanufacturing method for increasing the service life of a slag lock valve according to claim 1, characterized in that: In the step 5, when the diamond-like coating is deposited on the sealing surfaces of the valve ball and the valve seat by the diamond-like coating preparation process, the diamond-like coating with a thickness of 2-5 μm is deposited on the sealing surfaces of the valve ball and the valve seat by the diamond-like coating preparation process; Before deposition through the diamond-like coating preparation process, a 50-100nm thick Cr transition layer is set between the composite coating and the diamond-like coating. XRD detection confirms the formation of a Cr3C2 gradient phase; the nanoindentation hardness HIT of the diamond-like coating is 85±5GPa, and the elastic modulus E is 450±50GPa.

7. The repair and remanufacturing method for increasing the service life of a slag lock valve according to claim 1, characterized in that: In step 6, when alloying the friction surfaces of the wear-resistant sleeves of the valve ball and the valve stem, the front and rear wear-resistant sleeves are made of HV750-grade Stellite 12 alloy, and the front and rear valve stems are made of HV550-grade Stellite 6 alloy, forming a hardness gradient ΔHV ≥ 200; when performing clearance control on the friction surfaces of the wear-resistant sleeves of the valve ball and the valve stem, a hydraulic expansion tool is used to adjust the fitting clearance of the wear-resistant sleeves of the valve ball and the valve stem to 0.08-0.12 mm, and the rotation centers of the valve ball and the valve stem are on the same center line.

8. A maintenance and remanufacturing device for increasing the service life of a slag lock valve, characterized in that: It includes a workbench, the surface of which is symmetrically and slidingly connected to an electric furnace, a clamp is provided at the center between the two electric furnaces, a valve stem and a valve ball are clamped on the clamp, the bottom of the clamp passes through the surface of the workbench and is connected to a first transmission gear, a second transmission gear is meshed with the outer side of the first transmission gear, the second transmission gear is connected to the driving end of the servo motor through a transmission shaft, and a spray welding robot is also provided on one side of the workbench.

9. The repair and remanufacturing device for increasing the service life of a slag lock valve according to claim 8, characterized in that: The surface of the workbench is symmetrically provided with guide rails, the bottoms of the two electric furnaces are each provided with a mounting plate, the four corners of the bottom of the mounting plate are each provided with a slider, and the slider is slidably connected to the guide rails.

10. The repair and remanufacturing device for increasing the service life of a slag lock valve according to claim 8, characterized in that: A plurality of bearing seats are also provided on one side of the bottom of the workbench close to the transmission shaft, and the transmission shaft is rotatably connected to the inside of the bearing seats.

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