A variable pressure outer ring milling deformation control device and method of use

Abstract

The application discloses a variable-pressure outer ring milling deformation control device and a use method, and belongs to the field of precision machining of an aero-engine. The device comprises a base plate, a disc, a stand and a plurality of sets of adjustable expansion units. Each unit is composed of an expansion block, a support block, an adjusting support rod and an upper and lower sliding block assembly. The outer surface of the expansion block is consistent with the fan-shaped surface of the workpiece. The expansion block is driven to move radially by rotating the adjusting support rod independently, so that full-surface gapless fitting and uniform tightening are realized, and the radial position is limited by a positioning block. The use method comprises the following steps: initial tightening detection before rough machining, loosening the workpiece to release residual stress after rough machining, and fine machining to size after secondary precise tightening detection before fine machining. The application overcomes the defects of stress concentration and the inability to support the full surface of the whole expansion petal, realizes stress dissipation and deformation whole-process control, and a set of tooling can be adapted to workpieces of multiple specifications, thereby significantly improving the shape and position accuracy and the qualified rate of parts.

Description

Technical Field

[0001] This invention relates to the field of precision machining technology for aero-engine components, specifically to a deformation control device and its usage method for diffuser outer ring milling. Background Technology

[0002] The diffuser outer ring is a crucial component of aero-engine diffusers, belonging to the category of thin-walled, complex, ring-shaped precision parts. Its machining accuracy directly impacts engine airflow efficiency, operational stability, and overall performance. These parts typically feature internal fan-shaped surfaces and reinforcing ribs, as well as external bosses. They are generally characterized by thin walls, poor rigidity, complex structures, and stringent geometric tolerances. During CNC milling, machining deformation is highly likely, severely restricting part yield and machining quality.

[0003] Currently, existing expansion and tensioning fixtures are commonly used for outer ring milling operations, but they have the following technical defects in actual machining: 1. Due to limitations in machining accuracy and elastic reset consistency, the expansion flap structure of the integral type has deviations in the tensioning stroke of each expansion flap. The tensioning force on the inner wall of the outer ring cannot be evenly distributed. The thin-walled annular sidewall is prone to local stress overload, resulting in elastic deformation during the clamping stage. After machining, the stress is released, and the part's roundness, coaxiality and other dimensional and positional tolerances are seriously out of tolerance, which may even lead to irreversible plastic deformation.

[0004] 2. Due to the special structure of the fan-shaped surface and reinforcing ribs on the inner wall of the outer diffuser ring, the integral expansion valve fixture cannot provide full-surface support. There is a gap between the expansion valve and the inner part of the outer diffuser ring. Under the continuous action of cutting force, the side wall of the workpiece is prone to large elastic deformation, resulting in the machining surface wall thickness and surface roughness failing to meet the machining tolerance requirements.

[0005] 3. The integral expansion flap has a fixed size structure, and the inner diameter and contour cannot be adjusted. It can only be used for expansion outer ring workpieces of a single specification size. For different diameters, special tooling needs to be redesigned. The tooling investment cost is high, and the replacement and debugging process is cumbersome, which cannot meet the needs of new product development and production.

[0006] 4. The tooling lacks stress buffering and balancing structure. During the machining process, the internal residual stress caused by the removal of the blank material cannot be effectively relieved. At the same time, the tensioning clamping stress and the cutting force are superimposed. After finishing, the workpiece stress is gradually released, which can easily lead to subsequent warping and shrinkage deformation, making it difficult to guarantee the part qualification rate.

[0007] To address the aforementioned challenges in deformation control, some improvements have been proposed in existing technologies. For example, CN117283323A proposes a fixture and clamping method for controlling the deformation of thin-walled high-temperature alloy parts during milling. This method employs multiple floating support structures and pressure plate structures on a rotating base. By adjusting the height of the support blocks, the flatness of the top surface of the outer ring of the part to be processed is adjusted, thereby improving processing efficiency and yield. CN217571900U discloses a high-precision diffuser milling fixture. By connecting an adjustable-height support assembly and a positioning ring on the chassis, it achieves edge support positioning of the diffuser and clamping processing after flattening. The structure is simple and easy to operate. However, these solutions still fail to solve the problem of gapless support across the entire surface of the fan-shaped surface of the inner wall of the diffuser's outer ring and the special structure of the reinforcing ribs. They cannot achieve uniform distribution of clamping force and effective dissipation of processing stress, and are still insufficient in ensuring the roundness, coaxiality, and other dimensional and positional accuracy of thin-walled annular parts.

[0008] In summary, existing machining tooling and processes cannot effectively solve the deformation problem in the milling of outer rings with diffuser, resulting in high scrap rate, low machining efficiency and difficulty in ensuring accuracy. There is an urgent need to develop an adjustable deformation control device to achieve high-precision, low-deformation milling of such thin-walled ring parts. Summary of the Invention

[0009] The purpose of this invention is to address the technical problems in existing diffuser outer ring milling processes, such as clamping stress concentration, cutting force deformation, and residual stress release deformation, by providing a deformation control device and method for diffuser outer ring milling. This device achieves uniform clamping force distribution, all-round rigid support of the workpiece surface, and precise control of machining stress, thereby suppressing milling deformation at its source, improving part machining accuracy and yield, and enhancing work versatility and machining efficiency.

[0010] The technical solution of the present invention: a deformation control device for diffuser outer ring milling, comprising a chassis and a disc coaxially fixed above the chassis via a column. The upper surface of the chassis is provided with multiple positioning blocks along the circumference and a sliding block assembly located inside the positioning blocks; The upper surface of the disk is provided with multiple upper slider assemblies and support assemblies along the circumference. The support assembly includes a support fixed on the disk, and an adjusting support rod is horizontally inserted through the support. The device also includes expansion blocks corresponding to the number of lower slider assemblies. The outer surface of the expansion blocks is used to fit with the fan-shaped surface of the diffuser outer ring. The lower end of each expansion block is set on the corresponding lower slider assembly, and a support block is fixedly connected to the inner end face of the expansion block. The lower end face of the support block is fixedly set on the corresponding upper slider assembly. One end of the adjusting support rod is connected to the support block. By rotating the adjusting support rod, the support block and the expansion block can be driven to move radially under the guidance of the upper and lower slider assembly, so that the outer surface of the expansion block and the fan-shaped surface of the expansion ring can be fitted without gap and uniformly tightened, and the lower part of the expansion block forms a radial limit when it moves to abut the positioning block.

[0011] Furthermore, the lower slider assembly includes a lower slide groove and a lower slider. The lower slide groove is fixed on the chassis, and the lower slider is slidably disposed on the lower slide groove. The lower slider is fixedly connected to the lower end of the expansion block.

[0012] Furthermore, the upper slider assembly includes an upper slider and an upper sliding groove. The upper slider is fixed on the disk, and the upper sliding groove is slidably disposed on the upper slider and is fixedly connected to the lower end face of the support block.

[0013] Furthermore, the positioning block is positioned on the chassis by a cylindrical pin and fixed by screws; the positioning block is used for quick and accurate positioning of the workpiece to ensure the coaxiality of the workpiece installation; multiple A-type movable pressure plates for clamping the workpiece are also provided on one side of the outer circle of the positioning block.

[0014] Furthermore, the A-type movable pressure plate has a waist-shaped hole in the middle. One end of the hole is connected to the chassis through a single-ended stud. The upper end of the single-ended stud is supported on the lower part of the A-type movable pressure plate. The connection between the single-ended stud and the chassis is locked by a hexagonal thin nut. The other end is connected to the chassis through a double-ended stud. After the double-ended stud passes through the waist-shaped hole, it is pressed and fixed by a shouldered hexagonal nut.

[0015] Furthermore, the support block has a T-shaped structure, including a back plate and a connecting block vertically disposed in the middle of the back plate, and the end of the connecting block has an opening groove; one side of the back plate of the support block is fixedly connected to the middle position of the expansion block by a cylindrical pin and screws; one end of the adjusting support rod is installed in the opening groove.

[0016] Furthermore, both the chassis and the disc are annular structures with a hollow central area; multiple columns are arranged along the circumference between the chassis and the disc, with the lower end of the columns fixedly connected to the chassis and the upper end fixedly connected to the disc.

[0017] Furthermore, the chassis, disc, positioning block, support block, and support are all made of 45# steel with a hardness of HRC35-40; the chassis is also equipped with multiple eye bolts for hoisting the device.

[0018] A method for using a deformation control device in diffuser milling of outer rings includes the following steps. Step 1: Install the device on the machine tool worktable, align the center of the device with the center of the worktable, and then fix it. Step 2: Place the processed inner surface of the expansion ring on the device, and adjust the circumferential position of the expansion ring so that each expansion block corresponds to each sector surface of the inner wall of the expansion ring, avoiding contact between the expansion block and the reinforcing rib. Step 3: Rotate each adjusting support rod in sequence to make each expansion block contact and tighten with the corresponding sector surface. After checking that the circular runout of the outer surface of the expansion ring is qualified, press the workpiece with the A-type moving pressure plate. Step 4: Roughly machine the outer surface of the diffuser ring, leaving a margin of 0.5 to 1 mm; Step 5: After rough machining, loosen the expansion blocks and A-type moving pressure plates in sequence to release stress; Step 6: Rotate each adjusting support rod in sequence again to make each expansion block contact and tighten with the corresponding sector surface. After checking that the circular runout of the outer surface of the expansion ring is qualified, press the workpiece again by moving the A-type pressure plate. Step 7: Perform precision machining on the outer surface of the diffuser ring to meet dimensional requirements.

[0019] Furthermore, in step 3, after tensioning, the circular runout of the upper, middle, and lower sections on the outer surface of the expansion ring is checked. It is required that the change in circular runout of the corresponding area of ​​each expansion block is less than 0.1 mm, and the circular runout of the three sections is less than 0.2 mm respectively. In step 6, after tensioning, check the circular runout of the upper, middle and lower sections on the outer surface of the expansion ring. The circular runout change of the corresponding area of ​​each expansion block is required to be less than 0.05mm, and the circular runout of the three sections is less than 0.1mm respectively.

[0020] The beneficial effects of this invention are: (1) This invention overcomes the defects of uneven stroke and inconsistent elastic reset of the integral expansion valve, realizes uniform expansion and support of the inner wall of the outer ring of the diffuser, avoids local stress overload, and has no elastic deformation during clamping, significantly improving the dimensional accuracy such as roundness and coaxiality. (2) This invention achieves gapless fit support for the special structure of the fan-shaped surface and reinforcing ribs, which greatly reduces elastic tool deflection under heavy cutting force, ensures stable wall thickness and surface roughness requirements, and solves the pain point of "tool deflection exceeding tolerance". (3) This invention breaks through the limitation of fixed size, and the internal expansion and contour can be adjusted. One set of tooling can be adapted to multiple specifications of expansion outer rings, which greatly reduces tooling costs, simplifies changeover and debugging, and meets the development needs of multiple varieties and new products. (4) The present invention has stress relief and buffering functions, effectively releases residual stress in materials, avoids the superposition of clamping stress and cutting force, suppresses warping and shrinkage deformation after finishing, and improves the long-term dimensional stability of parts. (5) This invention controls deformation throughout the entire process of clamping, cutting and stress release, significantly improving the first pass rate and shortening the research and development and production cycle. It is suitable for the high-quality manufacturing needs of precision parts for aero-engines. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic cross-sectional view of the outer diffuser ring of the present invention.

[0023] Figure 2 This is a top view of the deformation control device for the present invention.

[0024] Figure 3 for Figure 2 Schematic diagram of the BB cross section.

[0025] Figure 4 This is an isometric side view of the concealed expansion block and support block of the deformation control device of the present invention.

[0026] Figure 5 This is a schematic diagram of the support block, support base, and adjusting support rod of the deformation control device of the present invention.

[0027] Figure 6 A schematic diagram of the groove and slider for the invention of a deformation control device.

[0028] In the diagram: 1. Expansion ring; 101. Fan-shaped surface; 102. Reinforcing rib; 2. Base plate; 3. Hexagonal thin nut; 4. Single-ended stud; 5. Type A movable pressure plate; 6. Shoulder-mounted hexagonal nut; 7. Double-ended stud; 8. Column; 9. Socket head cap screw; 10. Expansion block; 11. Support block; 12. Socket head cap screw; 13. Adjusting support rod; 14. Upper slide groove; 15. Upper slider; 16. Socket head cap screw; 17. Socket head cap screw; 18. Lower slider; 19. Eye bolt; 20. Lower slide groove; 21. Positioning block; 22. Socket head cap screw; 23. Cylindrical pin; 24. Cylindrical pin; 25. Support; 26. Socket head cap screw; 27. Socket head cap screw; 28. Disc. Detailed Implementation

[0029] 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.

[0030] Reference Figure 1 - Figure 6 A deformation control device for expansion milling of outer rings includes a base 2, a hexagonal thin nut 3, a single-ended stud 4, an A-type movable pressure plate 5, a shouldered hexagonal nut 6, a double-ended stud 7, a column 8, a hexagonal head screw 9, an expansion block 10, a support block 11, a hexagonal head screw 12, an adjusting support rod 13, an upper sliding groove 14, an upper sliding block 15, a hexagonal head screw 16, a hexagonal head screw 17, a lower sliding block 18, a lifting eye screw 19, a lower sliding groove 20, a positioning block 21, a hexagonal head screw 22, a cylindrical pin 23, a cylindrical pin 24, a support 25, a hexagonal head screw 26, a hexagonal head screw 27, and a disc 28. All tooling parts work together to achieve integrated deformation control of workpiece clamping, support, and positioning.

[0031] The chassis 2 is a circular base with multiple positioning blocks 21 on the upper end. The positioning blocks 21 are positioned by cylindrical pins 23 and fixed on the chassis 2 by hexagonal head screws 22. This is used for quick and accurate positioning of the workpiece to ensure the coaxiality of the workpiece during installation.

[0032] On one side of the outer circle of the positioning block 21, multiple A-type movable pressure plates 5, double-ended studs 7, single-ended studs 4, hexagonal thin nuts 3, and shouldered hexagonal nuts 6 are also provided for clamping the workpiece. The A-type movable pressure plate has a waist-shaped hole in the middle. One end of the A-type movable pressure plate 5 is connected to the chassis 2 through the single-ended stud 4, and the upper end of the single-ended stud 4 is supported on the lower part of the A-type movable pressure plate 5. A hexagonal thin nut 3 is provided at the contact point with the chassis for locking. The other end is connected to the chassis 2 through the double-ended stud 7, and the double-ended stud 7 is fixed and pressed by the shouldered hexagonal nut 6 after passing through the waist-shaped hole.

[0033] Multiple sliding grooves 20 are provided on one side of the inner circle of the positioning block 21. The sliding grooves 20 are fixed to the chassis 2 with hexagonal head screws. A sliding block 18 is provided on each sliding groove 20. The sliding block 18 is fixed to the lower end of the expansion block 10 by hexagonal head screws 17.

[0034] Multiple columns 8 are set on one side of the inner circle of the sliding groove 20. The lower end of the column 8 is connected to the chassis 2 by a hexagon socket head cap screw 9, and the upper end is connected to the disc 28 by a hexagon socket head cap screw 9.

[0035] Multiple upper sliding grooves 14, upper sliding blocks 15, and supports 25 are provided on the upper end of the disc 28. The upper sliding blocks 15 are connected to the disc 28 by internal hexagonal head screws 16. The upper sliding grooves 14 are located above the upper sliding blocks 15 and are connected to the support block 11 below by internal hexagonal head screws 27.

[0036] The support block 11 has a "T" shaped structure. One side of the support block 11 is connected to the middle of the expansion block 10 by a cylindrical pin 24 and an internal hexagonal head screw 12.

[0037] The support 25 is connected to the disc 28 by a hexagon socket head cap screw 26. A threaded adjusting support rod 13 is provided on the support 25, and one side of the adjusting support rod 13 is connected to the opening slot on the support block 11. Each expansion block is connected to a support block, adjustable support rod, support, upper slider, upper slide groove, lower slider, and lower slide groove, which together form a set of expansion and tightening adjustable devices. The number of adjustable devices corresponds to the number of fan-shaped surfaces on the outer diffuser ring.

[0038] Rotate the adjusting support rod to drive the support block and expansion block to move radially, thereby tightening the outer ring of the expansion block; the expansion block is made of high-hardness polyurethane material, which has high load-bearing capacity, high damping, oil resistance and wear resistance, and can withstand heavy cutting impact. The outer surface of the expansion block is consistent with the fan-shaped surface on the outer ring of the expansion block. The chassis, disc, positioning block, support block and support are made of 45# steel with HRC35~40. The chassis is equipped with multiple eye bolts for hoisting the device, and there are more than 6 positioning blocks.

[0039] This invention also provides a method for using the deformation control device for diffuser outer ring milling, comprising the following steps: (1) Install the device onto the machine tool worktable, align the center of the device with the center of the worktable, and fix it on the worktable; (2) Place the processed inner surface of the expansion ring into the device, adjust the circumferential position of the expansion ring to ensure that the expansion block 10 corresponds one-to-one with the fan-shaped surface 101, and avoid the expansion block 10 from contacting the reinforcing rib 102. (3) Rotate the adjustment support rod 13 in sequence to ensure that the expansion block 10 is in contact with the fan-shaped surface 101. Use a dial indicator to check the circular runout of the upper, middle and lower sections on the outer surface of the expansion ring. The change in circular runout corresponding to each expansion block 10 should be less than 0.1mm. After tightening, the circular runout of the three sections should be less than 0.2mm respectively. Then tighten the parts. (4) Rough machining of the outer surface of the diffuser ring is performed using a Φ25 diameter four-flute indexable carbide end mill with a allowance of 0.5 to 1 mm. (5) After rough machining is completed, loosen the expansion valve and pressure plate in sequence to release stress; (6) Rotate the adjusting support rod in sequence to ensure that the expansion block 10 is in contact with the fan-shaped surface 101. Use a dial indicator to check the circular runout of the upper, middle and lower sections on the outer surface of the expansion ring. The change in circular runout corresponding to each expansion block should be less than 0.05mm. After tightening, the circular runout of the three sections should be less than 0.1mm respectively. Then tighten the parts. (7) The outer surface of the diffuser ring is precision machined using an integral carbide end mill with a diameter of Φ8 ~ Φ12 and a tip radius of R1, until the required dimensions are achieved.

[0040] (8) After finishing, disassemble the parts.

[0041] Example 1: This example provides a deformation control device for expansion outer ring milling, which solves the technical problems of workpiece deformation caused by uneven expansion force, inability to support the entire surface, poor versatility, and inability to relieve stress in existing integral expansion valve tooling.

[0042] like Figures 1 to 6 As shown, the device includes a chassis 2, a disc 28, a plurality of expansion blocks 10, and an upper slider assembly, a lower slider assembly, and a support assembly that are matched with each expansion block 10.

[0043] Both the chassis 2 and the disc 28 are annular structures with a hollow central area. They are coaxially connected by multiple columns 8. The columns 8 are distributed along the circumference, with their lower ends fixed to the chassis 2 by hexagonal head screws 9, and their upper ends also fixed to the disc 28 by screws. The chassis 2, disc 28, positioning block 21, support block 11, and support 25 are all made of 45# steel with a hardness of HRC35-40. The chassis 2 is also equipped with multiple eye bolts 19 for overall hoisting.

[0044] On the outer edge of the upper surface of the chassis 2, multiple positioning blocks 21 are evenly distributed along the circumference, with a quantity greater than 6. Each positioning block 21 is precisely positioned on the chassis 2 by a cylindrical pin 23 and then fastened by an internal hexagonal head screw 22, used for quick and accurate positioning of the workpiece to be processed, ensuring the coaxiality of the workpiece installation. On one side of the outer circle of the positioning block 21, multiple A-type movable pressure plates 5 are also provided for pressing the workpiece from the outside. The A-type movable pressure plate 5 has a waist-shaped hole in the middle, one end of which is connected to the chassis 2 by a single-ended stud 4, the upper end of which is supported on the lower part of the pressure plate, and the connection is locked with a hexagonal thin nut 3; the other end is passed through the waist-shaped hole by a double-ended stud 7 and then pressed and fixed by a shouldered hexagonal nut 6.

[0045] On one side of the inner circle of the positioning block 21, a plurality of sliding grooves 20 are fixed along the circumference on the upper end surface of the chassis 2. Each sliding groove 20 is slidably fitted with a sliding block 18, which can slide radially within the sliding groove 20.

[0046] On the upper surface of the disc 28, a plurality of upper sliders 15 are fixed along the circumference. Each upper slider 15 is slidably fitted with an upper sliding groove 14, which can slide radially on the upper slider 15. A plurality of supports 25 are also fixed on the disc 28, and a threaded adjusting support rod 13 is horizontally inserted through each support 25.

[0047] The expansion blocks 10 are the core actuators of this device. Their number is the same as the number of fan-shaped surfaces 101 on the inner wall of the diffuser outer ring, and they correspond one-to-one. The expansion blocks 10 are made of high-hardness polyurethane material, which has the characteristics of high load-bearing capacity, high damping, oil resistance and wear resistance, and can withstand heavy cutting impacts. The outer surface of the expansion blocks 10 is completely consistent with the profile of the fan-shaped surfaces 101 of the diffuser outer ring, ensuring no gaps during fitting.

[0048] The lower end of each expansion block 10 is fixedly connected to the corresponding lower slide block 18 by screws; a support block 11 is fixedly connected to the middle of the inner end face of the expansion block 10. The support block 11 has a "T" shaped structure, including a back plate and a connecting block vertically disposed in the middle of the back plate, with an opening groove at the end of the connecting block; one side of the back plate is fixedly connected to the expansion block 10 by a cylindrical pin 24 and screws 12. The lower end face of the support block 11 is fixedly connected to the corresponding upper slide groove 14 by screws. One end of the adjusting support rod 13 is inserted into the opening groove at the end of the connecting block of the support block 11.

[0049] In this embodiment, each expansion block 10 is connected to a support block 11, an adjusting support rod 13, a support 25, an upper slider 15, an upper sliding groove 14, a lower slider 18, and a lower sliding groove 20, which together constitute a set of adjustable tensioning devices. The adjusting support rod 13 of each set of adjustable devices can be rotated independently.

[0050] During clamping, the expanded outer ring 1 with its inner surface already machined is placed inside the positioning block 21. The adjusting support rod 13 of each adjustable device is rotated independently. Since the adjusting support rod 13 is threadedly engaged with the support 25, and its end is limited within the opening groove of the support block 11, rotating the adjusting support rod 13 drives the support block 11 to move radially. Guided by the upper sliding groove 14 and the upper sliding block 15, and guided by the lower sliding block 18 and the lower sliding groove 20, the support block 11 drives the expansion block 10 to move smoothly and synchronously radially until the outer surface of the expansion block 10 and the fan-shaped surface 101 of the expanded outer ring achieve a gapless fit. Adjustment continues until the lower end of the expansion block 10 abuts against the positioning block 21, forming a radial limit, completing uniform tensioning. Finally, the workpiece is pressed tightly by the A-type moving pressure plate 5.

[0051] This structure solves the defects of uneven stroke and local stress overload in existing integral expansion blocks. Each expansion block is independently adjustable, which can precisely control the expansion amount of each sector area, achieving uniform expansion support throughout the entire area and preventing elastic deformation during clamping. The polyurethane expansion blocks are consistent with the sector surface, achieving a gapless, rigid support across the entire surface. This significantly reduces elastic tool deformation under subsequent heavy cutting, ensuring wall thickness and surface roughness. Furthermore, the independent adjustment of each adjustable device allows one set of tooling to accommodate expansion rings of different sizes. The expansion inner diameter can be changed simply by adjusting the screw-in amount of the adjusting support rod, making it highly versatile. In addition, the operation of loosening and re-tightening the workpiece after rough machining, combined with the high-damping polyurethane expansion blocks, effectively releases and disperses internal residual stress caused by material removal, avoiding the superposition of clamping stress and cutting force, suppressing warping and shrinkage deformation after finishing, and improving the long-term dimensional stability of the parts.

[0052] Example 2: This example provides a method for milling a diffuser outer ring using the device described in Example 1. Its core principle lies in the full-process deformation control strategy of "independent adjustable fit and tension—rough machining—stress release—re-precision tension—finish machining," suppressing machining deformation at each stage of clamping, cutting, and stress release. Specifically, it includes the following steps: Step 1: Device Installation and Alignment. Hoist the entire device onto the machine tool worktable. After aligning the center of the device with the rotation center of the worktable, secure the base plate 2 to the worktable using pressure plates or screws. Ensuring the coaxiality of the device installation is fundamental to subsequent machining accuracy.

[0053] Step 2: Workpiece placement and alignment. Place the expanded outer ring 1, which has been machined with inner surfaces (including fan-shaped surfaces 101 and reinforcing ribs 102), on the device. Rotate the workpiece to adjust its circumferential position, ensuring that each expansion block 10 corresponds one-to-one with the fan-shaped surface 101 on the inner wall of the workpiece. Avoid contact between the expansion block 10 and the reinforcing rib 102 to prevent interference, and ensure that the force acts directly on the main body of the surface.

[0054] Step 3: Tensioning and Inspection Before Rough Machining. Rotate the adjusting support rods 13 of each adjustable device in sequence to make each expansion block 10 contact and tighten with the corresponding sector surface 101. Then, use a dial indicator to check the circular runout of the upper, middle, and lower sections of the outer surface of the expansion ring. The circular runout variation of each expansion block's corresponding area should be less than 0.1 mm, and the overall circular runout of the three sections should be less than 0.2 mm. This accuracy requirement ensures that the clamping deformation caused by uneven blank allowance during the rough machining stage is controlled within the allowable range. After passing the inspection, tighten the shouldered hexagonal nuts 6 on each type A moving pressure plate 5 to clamp the workpiece.

[0055] Step 4: Rough Machining. Use a four-flute indexable carbide end mill with a 25mm diameter insert to rough machine the outer surface of the diffuser ring, leaving a 0.5-1mm finishing allowance on each side. The large insert and four-flute design ensure a high metal removal rate and cutting rigidity.

[0056] Step 5: Stress Relief. After rough machining, loosen all the clamping of the A-type moving pressure plates 5 in sequence, and then rotate the adjusting support rod 13 in the opposite direction to retract the expansion block 10 and release the workpiece. The purpose of this step is to allow the residual stress redistributed inside the workpiece due to the removal of a large amount of material during rough machining to be released freely, so as to avoid its superposition with the cutting stress of subsequent finishing machining.

[0057] Step 6: Precision tensioning and inspection before finishing. Rotate each adjusting support rod 13 again to re-engage and tighten the expansion block 10 with the fan-shaped surface 101. Use a dial indicator to check the circular runout of the upper, middle, and lower sections of the outer surface of the expansion ring. The requirements before finishing are stricter: the circular runout change in the corresponding area of ​​each expansion block must be less than 0.05mm, and the overall circular runout of the three sections must be less than 0.1mm. Re-tightening after stress release eliminates residual deformation from rough machining, providing a stable, high-precision clamping reference for finishing. After passing the inspection, tighten the workpiece again using the A-type moving pressure plate 5.

[0058] Step 7: Finishing. Select a solid carbide end mill with a diameter of Φ8~Φ12mm and a tip radius of R1 to finish the outer surface of the diffuser ring, directly machining to the final dimensions and surface roughness requirements. Small-diameter, rounded-corner solid carbide tools have low cutting force and low vibration. Combined with the uniform rigid support of the workpiece surface already obtained at this point, it can effectively suppress tool deflection and chatter marks, ensuring uniform wall thickness and surface quality.

[0059] Step 8: Disassemble the workpiece. After finishing, loosen the A-type movable pressure plate 5 and the expansion block 10, and remove the finished expansion outer ring.

[0060] This method decouples the main contradiction causing deformation—clamping stress, cutting stress, and residual stress—by performing two independent tensioning cycles before and after roughing: uniform support is used to control initial cutting deformation before roughing, residual stress is released after roughing, and a uniform support datum is re-established with higher precision before finishing, thereby achieving deformation control throughout the entire process and significantly improving the first-pass yield of parts.

[0061] The above provides a detailed description of the deformation control device and its usage method for diffuser outer ring milling provided by the present invention. Specific examples have been used to illustrate the structure and working principle of the invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A deformation control device for diffuser milling of outer rings, characterized in that: It includes a chassis (2) and a disc (28) coaxially fixed above the chassis via a column (8). The upper end face of the chassis (2) is provided with a plurality of positioning blocks (21) and a sliding block assembly located inside the positioning blocks (21) along the circumference; The upper surface of the disk (28) is provided with multiple upper slider assemblies and support assemblies along the circumference. The support assembly includes a support (25) fixed on the disk (28), and an adjusting support rod (13) is horizontally inserted through the support (25). The device also includes expansion blocks (10) corresponding to the number of lower slider assemblies. The outer surface of the expansion block (10) is used to fit with the fan-shaped surface (101) of the diffuser outer ring. The lower end of each expansion block (10) is set on the corresponding lower slider assembly. The inner end face of the expansion block (10) is fixedly connected to a support block (11). The lower end face of the support block (11) is fixedly set on the corresponding upper slider assembly. One end of the adjusting support rod (13) is connected to the support block (11). By rotating the adjusting support rod (13), the support block (11) and the expansion block (10) can be driven to move radially under the guidance of the upper and lower slider assembly, so that the outer surface of the expansion block (10) and the fan-shaped surface (101) of the expansion ring can be fitted without gap and uniformly tightened, and the lower part of the expansion block (10) forms a radial limit when it moves to abut against the positioning block (21).

2. The deformation control device for diffuser outer ring milling according to claim 1, characterized in that: The sliding block assembly includes a sliding groove (20) and a sliding block (18). The sliding groove (20) is fixed on the chassis (2), and the sliding block (18) is slidably disposed on the sliding groove (20). The sliding block (18) is fixedly connected to the lower end of the expansion block (10).

3. The deformation control device for diffuser outer ring milling according to claim 1, characterized in that: The upper slider assembly includes an upper slider (15) and an upper sliding groove (14). The upper slider (15) is fixed on the disc (28), and the upper sliding groove (14) is slidably disposed on the upper slider (15). The upper sliding groove (14) is fixedly connected to the lower end face of the support block (11).

4. The deformation control device for diffuser outer ring milling according to claim 1, characterized in that: The positioning block (21) is positioned on the chassis (2) by a cylindrical pin and fixed by screws; the positioning block (21) is used for quick and accurate positioning of the workpiece to ensure the coaxiality of the workpiece installation; a number of A-type movable pressure plates (5) for clamping the workpiece are also provided on one side of the outer circle of the positioning block (21).

5. The deformation control device for diffuser outer ring milling according to claim 4, characterized in that: The A-type movable pressure plate (5) has a waist-shaped hole in the middle. One end of the plate is connected to the chassis (2) through a single-headed stud (4). The upper end of the single-headed stud (4) is supported on the lower part of the A-type movable pressure plate (5). The connection between the single-headed stud (4) and the chassis (2) is locked by a hexagonal thin nut (3). The other end is connected to the chassis (2) through a double-headed stud (7). After the double-headed stud (7) passes through the waist-shaped hole, it is pressed and fixed by a shouldered hexagonal nut (6).

6. The deformation control device for diffuser outer ring milling according to claim 1, characterized in that: The support block (11) has a T-shaped structure, including a back plate and a connecting block vertically arranged in the middle of the back plate. The end of the connecting block has an opening groove. One side of the back plate of the support block (11) is fixedly connected to the middle position of the expansion block (10) by a cylindrical pin and screw. One end of the adjusting support rod (13) is installed in the opening groove.

7. The deformation control device for diffuser outer ring milling according to claim 1, characterized in that: Both the chassis (2) and the disc (28) are circular ring structures with a hollow area in the middle. Multiple columns (8) are arranged along the circumference between the chassis (2) and the disc (28). The lower end of the column (8) is fixedly connected to the chassis (2), and the upper end is fixedly connected to the disc (28).

8. The deformation control device for diffuser outer ring milling according to claim 1, characterized in that: The chassis (2), disc (28), positioning block (21), support block (11) and support (25) are all made of 45# steel with a hardness of HRC35~40; the chassis (2) is also provided with a number of eye bolts (19) for hoisting the device.

9. A method of using the deformation control device for diffuser outer ring milling as described in any one of claims 1-8, characterized in that: Includes the following steps, Step 1: Install the device on the machine tool worktable, align the center of the device with the center of the worktable, and then fix it. Step 2: Place the processed inner surface of the expansion ring (1) on the device, adjust the circumferential position of the expansion ring (1) so that each expansion block (10) corresponds to each sector surface (101) of the inner wall of the expansion ring, and avoid contact between the expansion block (10) and the reinforcing rib (102). Step 3: Rotate each adjusting support rod (13) in sequence to make each expansion block (10) contact and tighten with the corresponding sector surface (101). After checking that the circular runout of the outer surface of the expansion ring is qualified, press the workpiece by moving the A-type pressure plate (5). Step 4: Roughly machine the outer surface of the diffuser ring, leaving a margin of 0.5 to 1 mm; Step 5: After rough machining, loosen the expansion block (10) and the A-type moving pressure plate (5) in sequence to release stress; Step 6: Rotate each adjusting support rod (13) again to make each expansion block (10) contact and tighten with the corresponding sector surface (101). After checking that the circular runout of the outer surface of the expansion ring is qualified, press the workpiece again by moving the A-type pressure plate (5). Step 7: Perform precision machining on the outer surface of the diffuser ring to meet dimensional requirements.

10. The method of use according to claim 9, characterized in that: In step 3, after tightening, check the circular runout of the upper, middle and lower sections on the outer surface of the expansion ring. It is required that the change in circular runout of the corresponding area of ​​each expansion block (10) is less than 0.1mm, and the circular runout of the three sections is less than 0.2mm respectively. In step 6, after tightening, check the circular runout of the upper, middle and lower sections on the outer surface of the expansion ring. It is required that the change in circular runout of the corresponding area of ​​each expansion block (10) is less than 0.05mm, and the circular runout of the three sections is less than 0.1mm respectively.

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