A method and apparatus for machining a high-temperature alloy diffuser casing

Abstract

This invention discloses a processing method and apparatus for a high-temperature alloy diffuser casing. By applying forces to the upper mounting edge, cone, and lower mounting edge of the diffuser casing, combined with heating and heat preservation, welding stress is removed and corrected. This invention combines the traditional welding stress removal and correction processes into a single hot-forming process. A processing apparatus including a cover plate, positioning ring, base plate, and pressure plate is designed to complete the hot-forming process. The difference in deformation during heating of the processing apparatus provides the correcting force, and the temperature and time parameters are adjusted to allow the hot-forming process to replace the traditional welding stress removal and correction processes. This invention improves processing efficiency, reduces energy consumption, and ensures the quality of the finished diffuser casing.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine manufacturing technology, specifically relating to a processing device and processing method for a high-temperature alloy diffuser casing. Background Technology

[0002] The diffuser casing is a typical component of aero-engines, widely used in various turbojet and turbofan engines. With the continuous development of materials science, high-temperature alloys, possessing excellent fatigue properties and fracture toughness, are increasingly used in engine parts. However, during welding, forming, and machining processes, internal stresses can easily be generated in these parts, leading to deformation. Once deformation occurs, manual correction is required, significantly increasing the production cycle and consequently raising production costs.

[0003] Currently, diffuser casings are typical irregular thin-walled parts. The current processing flow is: ...automatic argon arc welding - stress relief - correction - ... In actual processing, this flow uses upper and lower structures to apply pressure to the outer surface of the casing, because the wall thickness difference between the upper and lower mounting edges and the cone (t = 0.8~1.0mm) is large. Figure 2 As shown in the figure, it is difficult to control the amount of deformation during the correction process, which can easily lead to "misalignment" and damage to the parts, rendering them unusable. Summary of the Invention

[0004] This invention aims to design a processing method and apparatus for a high-temperature alloy diffuser casing. Based on the structural characteristics of the part and the coefficient of linear expansion of the material, the apparatus designs the gap dimensions of the upper and lower mounting edges and the cone, respectively, to achieve the purpose of overall thermal calibration of the diffuser casing. Simultaneously, by selecting appropriate temperature parameters, the traditional process of "removing welding stress and correcting" can be combined into a single "thermal calibration" step, improving the part's processing quality while significantly increasing the processing speed.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for processing a high-temperature alloy diffuser casing, wherein the upper mounting edge of the diffuser casing has a groove on its outer surface, and the lower mounting edge has a toothed outer surface. The processing method includes welding the upper mounting edge, the cone, and the lower mounting edge with different thicknesses by argon arc welding, and simultaneously eliminating welding stress and correcting the external dimensions by hot straightening after argon arc welding. During the hot straightening process, a straightening force is applied to the upper mounting edge, the cone, and the lower mounting edge as a whole in the following manner:

[0007] An axial force is applied from top to bottom to the upper end face of the upper mounting edge, and a radial force is applied from inside to outside to the inner annular surface of the upper mounting edge.

[0008] A radial force from the inside out is applied to the inner conical surface of the cone;

[0009] An upward axial force is applied to the lower end face of the lower mounting edge, an upward axial force is applied to the upper end face of the lower mounting edge, and an outward radial force is applied to the inner ring surface of the lower mounting edge.

[0010] As one approach, the upper mounting edge, cone, and lower mounting edge are assembled with the same thermal calibration fixture, and calibration is achieved by controlling the deformation of the upper mounting edge, cone, and lower mounting edge to be less than the deformation of the thermal calibration fixture during the thermal calibration process. The calibration amount is controlled by controlling the gap between the upper mounting edge, cone, and lower mounting edge and the surface of the thermal calibration fixture in the radial direction of the diffuser casing.

[0011] As one approach, a material with a linear expansion coefficient greater than that of the upper mounting edge, the cone, and the lower mounting edge during heating is selected as the material for preparing the thermal calibration fixture.

[0012] As one option, the upper mounting edge, the cone, and the lower mounting edge are made of GH3044 material;

[0013] The assembly fixture is made of 1Cr18Ni9Ti material;

[0014] The temperature for heat calibration is 900±10℃;

[0015] The heat-adjusted type has a heat preservation time of 3.5h to 4.0h.

[0016] A machining apparatus for a high-temperature alloy diffuser casing, comprising:

[0017] A base plate, wherein the outer diameter of the base plate is larger than the outer diameter of the lower mounting edge;

[0018] A positioning ring is detachably connected to the upper end face of the base plate. The positioning ring includes an upper annular surface and a lower annular surface, which are connected by a conical surface.

[0019] A cover plate, which is detachably mounted on the upper annular surface of the positioning ring;

[0020] Pressure plates are evenly distributed on the upper surface of the base plate, and at least a portion of them are located above the lower annular surface of the positioning ring.

[0021] As one option, the positioning ring is connected to the base plate by screws inserted into its lower annular surface.

[0022] As one option, the positioning ring has a weight-reducing groove on its tapered surface.

[0023] As one embodiment, the cover plate is connected to the upper annular surface of the positioning ring by a column that passes through it, and the column presses the cover plate and the upper annular surface of the positioning ring together by wedges and nuts.

[0024] As one option, an eccentric wheel is provided at the upper end of the pressure plate, and the shaft of the eccentric wheel is connected to the upper end face of the base plate through a hinge bolt. A handle is also connected to the eccentric wheel.

[0025] As one option, a lifting ring is provided on the upper surface of the base plate, and lifting screws are provided on the circumferential surface of the cover plate.

[0026] Compared to traditional cold calibration methods, the device designed in this invention applies pressure to the diffuser casing under high-temperature conditions, ensuring that the internal stress generated during welding and forming inside the diffuser casing is fully released. Compared to traditional hot calibration methods, the device designed in this invention, through reasonable gap design, performs overall calibration of the upper and lower mounting edges and cones with significant structural differences (mainly differences in shape and thickness), which traditional hot calibration methods cannot meet.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) By cooperating with the cover plate, positioning ring, bottom plate and pressure plate, and by controlling the thermal expansion coefficient of the hot-calibration fixture material to be greater than that of the diffuser casing, and by setting the gap difference between different positions on the hot-calibration fixture and different thickness positions of the diffuser casing, the difficulty of deformation control of the mounting edge, cone and lower mounting edge on complex casing parts is solved, and the problem of difficulty in removing the diffuser casing from the hot-calibration fixture after hot calibration is also solved.

[0029] (2) By adjusting the temperature and time parameters, the traditional stress relief and correction processes are optimized into one process, which improves processing efficiency and reduces energy consumption.

[0030] (3) The driving structure of the pressure plate, the clamping structure of the cover plate and the installation structure of the positioning ring are ingeniously designed, easy to install and remove and simple to operate.

[0031] (4) Through the design and manufacturing of this device, hot calibration is used instead of manual calibration, which not only ensures the size of the parts, but also eliminates stress concentration caused by welding and forming, thus improving product quality. Attached Figure Description

[0032] Figure 1 This is a comparison diagram of the traditional process route for the diffuser casing and the process route of the present invention.

[0033] Figure 2 This is a three-dimensional view of the diffuser housing in this invention;

[0034] Figure 3This is a schematic diagram of the assembly process in this invention;

[0035] Figure 4 This is a three-dimensional view of the positioning ring corresponding to the inner surface of the processing device in this invention;

[0036] Figure 5 This is a three-dimensional view of the diffuser casing after it has been assembled onto the processing device in this invention;

[0037] In the diagram: 1-Base plate; 2-Positioning ring; 3-Pressure plate; 4-Cover plate; 5-Column; 6-Wedge block; 7-Type A straight handle; 8-Fork-shaped eccentric wheel; 9-First cylindrical head hexagon socket screw; 10-Second cylindrical head hexagon socket screw; 11-Hook bolt; 12-Type A eye bolt; 13-Hexagonal thin nut; 14-First cylindrical pin; 15-Second cylindrical pin. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, it should not be construed that the scope of the subject matter of the present invention is limited to the following embodiments. All modifications, substitutions and alterations made based on ordinary technical knowledge and common practices in the art without departing from the above-described technical concept of the present invention are included within the scope of the present invention.

[0039] In this embodiment, a processing device is designed as a heat-calibrating fixture for a high-temperature alloy diffuser casing. The design concept of this processing device is as follows: Figure 2 As shown, the diffuser casing is an irregular thin-walled part. The outer surface of the upper mounting edge is a concave groove, the middle part is a thin-walled cone, and the outer surface of the lower mounting edge is toothed. The thicknesses of the upper mounting edge, the thin-walled cone, and the lower mounting edge are different. Based on the different coefficients of linear expansion, 1Cr18Ni9Ti was selected as the manufacturing material for the processing device. The clearance dimensions were rationally designed according to the part structure. For example, the upper and lower mounting edges are thicker, resulting in less deformation during welding, while the cone is thinner, leading to greater deformation. Therefore, considering the linear expansion of the thermal calibration fixture in the radial direction of the diffuser casing, the clearance between the profile of the corresponding upper and lower mounting edges on the thermal calibration fixture and the upper and lower mounting edges was increased, reducing the calibration amount of the thermal calibration fixture on the upper and lower mounting edges. Simultaneously, the clearance between the profile of the corresponding cone and the cone was decreased, increasing the calibration amount of the thermal calibration fixture on the cone. Thus, a single thermal calibration fixture can achieve overall thermal calibration of the upper and lower mounting edges and the cone of different thicknesses on the diffuser casing in a single heating process. This eliminates the need for separate fixtures to independently calibrate different thickness areas on the diffuser casing. After the hot calibration is completed, the hot calibration fixture can be disassembled smoothly because the shrinkage of the hot calibration fixture is greater than that of the diffuser housing.

[0040] like Figure 3 As shown, the deformation of the diffuser casing is controlled using the following method:

[0041] First, regarding the inner surface of the diffuser casing, such as... Figure 4 As shown, the base plate 1, positioning ring 2, and cover plate 4 are used for the fit. The base plate 1 and positioning ring 2 are fastened with second cylindrical head hexagonal screws 10, and the positioning ring 2 and cover plate 4 are fastened with columns 5, wedges 6, and hexagonal thin nuts 13. The inner surface of the diffuser casing is heat-corrected. According to the different linear expansion coefficients of the materials, a certain margin is left between the diffuser casing and the processing device. Under high temperature conditions, the deformation of positioning ring 2 is greater than the deformation of diffuser casing, so as to "squeeze" the diffuser casing to the ideal position to meet the size requirements of the diffuser casing.

[0042] Secondly, the lower mounting edge is pressed onto the base plate 1 using the hinge bolt 11, pressure plate 3, and fork-shaped eccentric wheel 8. The upper mounting edge is fixed using the column 5, wedge block 6, cover plate 4, and hexagonal thin nut 13. A three-dimensional view of the processing device after assembling the diffuser casing is shown below. Figure 5 As shown. Type A eye bolts 12 are designed on the base plate 1 as a lifting structure, and cylindrical head socket head cap screws 9 are designed on the cover plate 4 as a lifting structure, which facilitates assembly during hot forming.

[0043] By designing a reasonable gap (increasing the gap between the profile of the upper and lower mounting edges on the hot-calibrating fixture and the corresponding mounting edge, while decreasing the gap between the profile of the cone and the cone; the specific size of the gap is calculated based on the linear expansion coefficient of the hot-calibrating fixture material, the heating temperature, and the deformation of the upper and lower mounting edges and the cone; the basic principle is: calibration amount = linear expansion coefficient of the hot-calibrating fixture × (hot-calibrating temperature - initial temperature) × thickness of the hot-calibrating fixture at that position - gap), not only can the deformation of the upper and lower mounting edges be corrected simultaneously, but the straightness of the inner profile of the diffuser casing cone can also be ensured. Furthermore, the use of the A-type straight handle 7 and the fork-type eccentric wheel 8 (the A-type straight handle 7 is fixed to the fork-type eccentric wheel 8 via the first cylindrical pin 14, and the fork-type eccentric wheel 8 is connected to the hinge bolt 11 via the second cylindrical pin 15 as a pivot) enables fast and efficient loading and unloading of the diffuser casing, further improving the processing efficiency of the diffuser casing.

[0044] In this embodiment, the above-mentioned processing equipment is used in conjunction with process optimization to achieve deformation control of the high-temperature alloy diffuser casing.

[0045] like Figure 1 As shown, the current processing technology for the diffuser casing is "...automatic argon arc welding - stress relief - correction - ...". Through the design and use of the above processing device, the processing technology can be optimized to "...automatic argon arc welding - heat correction - ...".

[0046] by Figure 2 Taking the diffuser casing as an example, its material is GH3044, a solution-strengthened high-temperature alloy, and the solution treatment temperature is 1120–1160℃. The material of the processing device is 1Cr18Ni9Ti, an austenitic stainless steel, and the solution treatment temperature is 1060±10℃. Without changing the microstructure of the diffuser casing and the processing device, the parameters for heat straightening were explored through experiments. Finally, the heat straightening temperature was set at 900±10℃. Using this temperature to heat-treat the diffuser casing can both relieve welding stress and achieve the purpose of heat straightening.

[0047] Furthermore, regarding the selection of the heat-fitting insulation temperature, based on heat transfer theory, in addition to the thickness of the diffuser casing itself, the thickness of the processing equipment must also be considered. A short insulation time cannot achieve the purpose of heat-fitting, while a long insulation time will affect the diffuser casing substrate. Through experiments, the insulation time was finally determined to be 3.5h to 4.0h.

[0048] In summary, such as Figure 1 As shown, by designing and using the processing equipment, the processing technology of the diffuser casing is optimized from "...automatic argon arc welding - stress relief - correction - ..." to "...automatic argon arc welding - hot straightening - ...". This not only significantly shortens the processing cycle of the parts and reduces energy consumption, but also improves the processing quality of the parts and reduces deformation.

[0049] The following are the specific implementation steps of the present invention:

[0050] (1) Preparations before assembly:

[0051] Before using the device to assemble parts, the contact surfaces between the device and the parts must be cleaned to ensure that there are no dirt or foreign objects that could affect the thermal calibration of the parts. In addition, the surface of the parts also needs to be inspected to ensure that there is no mechanical damage or dirt.

[0052] (2) Component assembly:

[0053] First, use a crane to place the processing device on the ground, remove the wedge 6 and the cover plate 4 and place them aside. At the same time, rotate the A-type straight handle 7 to ensure that the pressure plate 3 can have enough space to place the lower installation edge.

[0054] Next, place the part coaxially on the positioning ring 2, ensuring that the lower mounting edge is tightly fitted with the base plate 1. Then, place the cover plate 4 on the upper mounting edge of the part, insert the wedge 6 and press it down, while rotating the A-type straight handle 7 to fasten the lower mounting edge to the base plate 3 through the pressure plate 3. (Note: During the tightening of the wedge 6 and the A-type straight handle 7, a diagonal tightening method must be used).

[0055] (3) Hot calibration type:

[0056] The assembled parts and processing equipment are hoisted onto the platform of the bogie furnace using a crane. The bogie furnace door is closed, the heating temperature is set to 900℃, and the holding time is 3.5 to 4.0 hours for heat calibration.

[0057] (4) Remove from the oven:

[0058] After the diffuser casing is heated, it is cooled to room temperature in the furnace. The diffuser casing and processing device are then lifted out of the trolley furnace. The wedge block 6 is removed and the cover plate 4 is taken off. The A-type straight handle 7 is rotated to release the pressure plate 3, and the diffuser casing is removed to complete the entire heat calibration process.

[0059] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A method for processing a high-temperature alloy diffuser casing, wherein the upper mounting edge of the diffuser casing has a groove and the lower mounting edge has a toothed shape, characterized in that: The processing method includes welding upper mounting edges, cones, and lower mounting edges of different thicknesses using argon arc welding. After argon arc welding, heat straightening is performed to simultaneously eliminate welding stress and correct the external dimensions. During the heat straightening process, a straightening force is applied to the upper mounting edges, cones, and lower mounting edges as a whole in the following manner: An axial force is applied from top to bottom to the upper end face of the upper mounting edge, and a radial force is applied from inside to outside to the inner annular surface of the upper mounting edge. A radial force from the inside out is applied to the inner conical surface of the cone; An upward axial force is applied to the lower end face of the lower mounting edge, an upward axial force is applied to the upper end face of the lower mounting edge, and an outward radial force is applied to the inner ring surface of the lower mounting edge. The upper mounting edge, cone, and lower mounting edge are assembled with the same thermal calibration fixture, and the calibration is achieved by controlling the deformation of the upper mounting edge, cone, and lower mounting edge to be less than the deformation of the thermal calibration fixture during the thermal calibration process. The calibration amount is controlled by controlling the gap between the upper mounting edge, cone, and lower mounting edge and the thermal calibration fixture profile in the radial direction of the diffuser casing. The material of the upper mounting edge, the cone, and the lower mounting edge is GH3044. The material of the heat-calibrated fixture is 1Cr18Ni9Ti; The temperature for heat calibration is 900±10℃; The heat-adjusted type has a heat preservation time of 3.5h to 4.0h.

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