A guard ring coating water jet stripping technology processing method

Abstract

The application provides a kind of protective ring coating water jet stripping technology processing method, it is related to surface coating water stripping cutting field, equipment research and development technical scheme is: gantry type water cutting platform is main body, while installing a set of high-pressure water jet cutting processing high-frequency generator, cooperate with centering AC five-axis cutter head and ECS control system and automatic sand supply tank, automatic sand removal system, soft water treatment system etc. Commonly constitute five-axis numerical control ultrahigh pressure water cutting machine. Main process is: preparation before cutting-water cutting coating processing-inspection. The application can realize the surface water stripping cutting processing of protective ring protective ring polyester coating parts with the gantry type water cutting platform with centering AC five-axis cutter head as main body, and the operability is enhanced.

Description

Technical Field

[0001] This invention belongs to the field of surface coating water stripping and cutting, specifically relating to a water jet stripping technology processing method for retaining ring coatings. Background Technology

[0002] In the field of gas turbines, the sealing structure of retaining ring components primarily functions to prevent the leakage of high-temperature gas from the high-speed rotating turbine rotor shaft system. It is a sealing technology designed for high-temperature and high-pressure differential conditions. Typical retaining ring seals generally employ a honeycomb structure, and honeycomb sealing technology is mature and widely used in various industries. The H25 gas turbine uses a comb-tooth honeycomb sealing structure, which alters the flow field structure within the comb teeth and honeycomb cavities, effectively reducing leakage. This project encountered many unprecedented technical challenges during its development. The processing of the first-stage retaining ring's comb-tooth grindable coating pattern required cutting the inner diameter surface polyester coating into an inclined comb shape, based on the spraying of the (base layer) Amperit 410.001 coating and the (top layer) 204B-NS + 15% polyester mixed coating. This required smooth boundaries, no chipping or peeling, and no damage to the underlying metal layer. The polyester coating has a loose, porous texture, cannot come into contact with oily media, and is relatively soft, making it very difficult to process. Achieving coating boundary quality using traditional milling methods is a significant technical challenge.

[0003] Currently, the common CNC milling process in China involves aligning and fixing the workpiece on the machine tool's rotary table, then using a cylindrical rotary milling cutter to mill the part while the cutting fluid is being applied. During machining, the spindle's oscillation and the table's servo feed work together to complete the milling of the inner circular surface of the ring-shaped workpiece, creating a comb-like groove. The parts involved in this project have a slightly soft coating (Rockwell hardness HR15Y after polyester removal heat treatment), which is prone to peeling and uneven thickness, easily damaging the underlying metal layer, and cannot come into contact with oily media. Traditional machining methods cannot achieve the machining of this type of part. Currently, there is no experience in China of waterjet stripping processing for this type of material's protective ring seals; processing equipment and processes are also lacking. Therefore, it is necessary to develop a reasonable and feasible process plan through extensive specialized process experiments, and on this basis, develop dedicated waterjet stripping processing equipment to solve the urgent production needs. Summary of the Invention

[0004] The purpose of this invention is to provide a gantry-type waterjet cutting platform with a centering AC five-axis cutter head as the main body to realize the surface water-jet peeling and cutting of protective ring polyester coated parts, thereby enhancing the operability of the protective ring coating waterjet peeling technology processing method.

[0005] A method for waterjet stripping of a protective ring coating includes a gantry-type waterjet cutting platform; a high-pressure waterjet generator suitable for high-pressure waterjet cutting is installed, along with an advanced centering AC five-axis cutter head, an ECS control system, an automatic sand supply tank, an automatic sand removal system, and a soft water treatment system, forming a five-axis CNC ultra-high-pressure waterjet cutting machine. The method includes the following steps:

[0006] Preparation before cutting: Install and fix the retaining ring on the gantry-type waterjet cutting platform using special tooling to ensure the workpiece is stable and secure, and protect the workpiece on all four sides to avoid damage from water jet splashes. Adjust the distance between the five-axis cutter head nozzle and the workpiece to align the workpiece with the zero point position of the CNC program, and set the machining parameters: feed rate and abrasive quantity.

[0007] Waterjet cutting coating processing: After installing the retaining ring and tooling, a processing test was conducted on a gantry-type waterjet cutting platform. Garnet with a 120-mesh abrasive was added to the water jet as the working medium, while water pressure was reduced. Corresponding safety precautions were implemented on the machine tool. The cantilever cutting head was positioned close to the workpiece surface; this method effectively controlled the dimensional accuracy of the water jet diameter.

[0008] Inspection: Inspect the coating surface. If it is not up to standard, adjust the water pressure and feed speed of the high-pressure generator according to the performance of the coating surface during water cutting. After the surface coating is removed by water cutting, repeat the above process until the inspection is up to standard.

[0009] Furthermore, the thickness tolerance of the comb teeth achieved by the water cutting is 0.2 mm, and the width tolerance of the comb teeth is ±1 mm.

[0010] Furthermore, the gantry-type waterjet cutting platform has an X-axis machining stroke ≥1000mm, a Y-axis machining stroke ≥1000mm, a Z-axis machining stroke ≥300mm, a nozzle vertical distance from the worktable surface ≥350mm, and five-axis five-linkage.

[0011] Furthermore, the maximum pressure of the high-pressure generator is not less than 50MPa, the pressure is adjustable from 10 to 50MPa, and the maximum flow rate is not less than 15L / min.

[0012] Furthermore, the centering AC five-axis cutter head has an infinite rotation function for the C-axis, a positioning accuracy of not less than 0.7°, an angle deviation of ±0.5° between the A-axis and the C-axis, and a maximum cutting angle of not less than 50°.

[0013] The beneficial effects of this invention are as follows: This invention utilizes a gantry-type waterjet cutting platform combined with an advanced centering AC five-axis cutter head. Waterjet cutting is a cold-state cutting process, with no chemical changes during the cutting process, and no adverse effects on the physical and chemical properties of the material being cut. It also offers advantages such as no deformation, narrow kerf, high precision, and a smooth, uncontaminated cut surface, which is suitable for the porous structure of polyester coatings and their inability to come into contact with oily media. This overcomes the limitations of traditional milling machining methods, which are prone to damaging the underlying metal due to uneven coating thickness. While meeting requirements in terms of dimensions, geometric tolerances, surface finish, and smooth surface boundaries without peeling or delamination, this invention is more widely applicable to the surface waterjet cutting of polyester-coated parts with protective rings, enhancing operability, saving costs, and improving efficiency. Attached Figure Description

[0014] Fig. 1 This is a flowchart of the present invention;

[0015] Fig. 2 Example image showing coating peeling and flaking;

[0016] Fig. 3 Example image showing a qualified coating pattern. Detailed Implementation

[0017] The present invention will now be further described with reference to the accompanying drawings.

[0018] like Figs. 1-3 As shown, a waterjet peeling method for retaining ring coatings is presented. A gantry-type waterjet cutting platform is the main body, equipped with a high-pressure waterjet generator suitable for high-pressure waterjet cutting. This, along with an advanced centering AC five-axis cutter head, ECS control system, automatic sand supply tank, automatic sand removal system, and soft water treatment system, forms a five-axis CNC ultra-high-pressure waterjet cutting machine. The cantilevered centering AC five-axis cutter head can track and oscillate according to the inner diameter surface position. Following the CNC program, the nozzle is always perpendicular to the curve normal to maintain positive pressure cutting, thus improving processing stability. High-pressure waterjet cutting, commonly known as waterjet cutting, utilizes high-pressure technology to pressurize sand-filled water to a certain pressure, then sprays it at high speed through a nozzle with an inner diameter of approximately 0.15–0.35 mm to form a water jet, which is then sprayed onto the workpiece surface to remove material. This method is used to complete the waterjet peeling of the retaining ring coating. The main process is: pre-cutting preparation - waterjet coating processing - inspection.

[0019] Preparation before cutting: Install and fix the retaining ring on the waterjet cutting platform using special tooling to ensure the workpiece is stable and secure, and protect the workpiece on all four sides to avoid damage from water jet splashes. Adjust the distance between the five-axis cutter head nozzle and the workpiece to align the workpiece with the zero point position of the CNC program, and set the machining parameters: feed rate and abrasive quantity.

[0020] Waterjet cutting coating processing: After installing the retaining ring and tooling, processing tests were conducted on a gantry-type waterjet cutting platform. It was found that using pure water-based working fluid as the working medium required higher water pressure during actual processing due to the strong bonding force between the composite coatings. However, the working conditions were very unstable, resulting in incomplete root cleaning, peeling, and flaking of the coating (e.g., ...). Fig. 2 The coating surface exhibited poor performance in terms of form and position tolerances and surface finish. This was because waterjet cutting with 120-mesh garnet abrasive added to the water improved the control of these tolerances and surface finish. Therefore, we ultimately chose 120-mesh garnet abrasive added to the water as the working medium for this machine tool, while reducing the water pressure and implementing corresponding safety measures. During processing, we also discovered that the nozzle's distance from the workpiece surface and the long spray distance caused excessive water jet diameter diffusion upon reaching the workpiece, resulting in low material removal accuracy and frequent coating boundary chipping and dimensional deviations. Based on these findings, we adjusted the nozzle position, moving the cantilever cutting head closer to the workpiece surface. This method effectively controlled the dimensional accuracy of the sprayed water jet diameter, resolving the coating boundary chipping and dimensional deviation issues, improving processing efficiency, and meeting the processing requirements for grindable coating patterns on retaining ring parts (such as...). Fig. 3 Table 1 shows the processing parameters used when machining the sealing coating retaining ring after equipment adjustment.

[0021] Table 1. Record of Processing Parameters for the Abrasive Coating Pattern of Level 1 Protective Ring Section

[0022]

[0023] Inspection: Inspect the coating surface. If it is not up to standard, adjust the water pressure and feed speed of the high-pressure generator according to the performance of the coating surface during water cutting. After the surface coating is removed by water cutting, repeat the above process until the inspection is up to standard.

[0024] The surface layer material is 204BNS + 15% Polyester, and the metal base layer material is Amperit 410.1; the thickness tolerance of the comb teeth achieved by waterjet cutting is 0.2mm, and the width tolerance is ±1mm; the gantry-type waterjet cutting platform has an X-axis machining stroke ≥1000mm, a Y-axis machining stroke ≥1000mm, and a Z-axis machining stroke ≥300mm (nozzle vertical distance from the worktable surface ≥350mm), with five axes and five-linkage; the maximum pressure of the high-pressure generator is not less than: 50MPa (pressure 1 Adjustable pressure (0-50MPa), maximum flow rate not less than 15L / min; centering AC five-axis cutter head, C-axis has infinite rotation function, positioning accuracy not less than 0.7°, A-axis and C-axis angle deviation ±0.5°, maximum cutting angle not less than 50°; ECS control system equipped with five-axis waterjet cutting programming software, the software supports importing UG 3D digital model format for programming; automatic sand supply tank is servo controlled, precisely controlling the sand supply; dynamic sand removal system can continuously remove waste sand from the waterjet cutting machine's water tank, with a separation flow rate not less than 9m³ / min. 3 / hour; The water softening system introduces a special softening agent into the water flow to passivate calcium and magnesium ions, thus softening the water. The water production capacity is no less than 0.5m³ / hour. 3 / h; water cutting pressure reaches 20Mpa, and feed speed reaches 0.5m / min.

[0025] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. 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 shroud coating water jet stripping technique machining method, characterized by, The machine comprises a gantry water cutting platform, a high-pressure generator suitable for high-pressure water jet cutting, an advanced centering AC five-axis cutter head, an ECS control system, an automatic sand supply tank, an automatic sand removal system, and a soft water treatment system. Before cutting, the grommet is fixed on the gantry water cutting platform with a special tooling to ensure the stability and firmness of the workpiece, and the workpiece is protected from water jet splashing. The distance between the five-axis cutter head nozzle and the workpiece is adjusted to find the zero point position of the workpiece numerical control program, and the machining parameters such as feed speed and sand amount are set. Water cutting coating processing: After the grommet is installed with tooling, the machining test is carried out on the gantry water cutting platform, garnet sand with a mesh size of 120 is added to the water as the working medium of the machine, which reduces the water pressure, and some corresponding safety protection measures are taken on the machine. The cantilever machining cutter head is close to the surface end of the workpiece, which effectively controls the size accuracy of the water jet beam diameter. Inspection: Check the coating surface, if unqualified, adjust the water pressure and feed speed of the high-pressure generator according to the performance of the coating surface during water cutting, and repeat the above process until the inspection is qualified. The gantry water cutting platform has an X-axis machining stroke ≥1000mm, a Y-axis machining stroke ≥1000mm, a Z-axis machining stroke ≥300mm, a nozzle vertical state distance from the workbench surface ≥350mm, and a five-axis five-linkage. The high-pressure generator has a maximum pressure not less than 50MPa, a pressure adjustable between 10-50MPa, and a maximum flow not less than 15L / min. The centering AC five-axis cutter head has an infinite rotation function of C-axis, a positioning accuracy not less than 0.7°, an A-axis and C-axis angle deviation ±0.5°, and a maximum cutting angle not less than 50°.

2. A method of processing a protective coating water jet stripping technology according to claim 1, characterized in that, The water cutting achieves a comb tooth thickness size tolerance of 0.2mm and a comb tooth width size tolerance of ±1mm.

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