Method for clamping and machining working ring slots for aero-engine fans

Abstract

This invention discloses a method for clamping and machining the slots of a fan working ring for an aero-engine, comprising the following steps: A) Pressing and fixing the fan working ring onto a precision hole machining station, first using a first submerged drill cutter to countersink the upper ring groove of the fan working ring, then using a drill bit to enlarge the countersinked hole and drill to the lower ring surface of the fan working ring, then using a second submerged drill cutter to drill through the double-layer ring groove of the fan working ring, and finally machining it into place with a reamer; B) Designing and manufacturing a special fixture, using the special fixture to support the entire surface of the fan working ring, and using a cover plate to press it, while simultaneously performing full-circle outer circle positioning to press and fix the fan working ring onto the lace groove machining station; C) Performing full-circle segmented milling of the lace groove to be machined on the fan working ring, wherein, after each segment of the lace groove is milled, the wall thickness of the fan working ring is measured first, then the tool compensation is adjusted according to the wall thickness of the fan working ring, and then the milling of the next segment of the lace groove is performed.

Description

Technical Field

[0001] This invention relates to the field of aero-engine parts processing technology, and in particular, to a method for clamping and processing the working ring slot of an aero-engine fan. Background Technology

[0002] In aero engines, the fan working ring is fitted around the rectifier blades. Its inner wall has threaded grooves with graphite. The fan working ring protects the rectifier blades or prevents blade fragments from falling off and damaging other parts through these grooves. The fan working ring is a ring forging with a relatively thin wall, making it a typical thin-walled ring part. Due to the threaded grooves on the inner wall, the overall rigidity of the fan working ring is poor, resulting in large deformation during machining and clamping. The outer wall of the fan working ring has decorative grooves and double-layered annular grooves. The decorative grooves serve to reduce weight and provide clearance, while the double-layered annular grooves facilitate assembly with the rectifier, reducing weight and facilitating disassembly. Precision holes are drilled along the axial direction of the fan working ring and pass through the double-layered annular grooves. These precision holes serve to limit and stop movement, preventing the rectifier from rotating freely in the circumference within the double-layered annular grooves.

[0003] However, existing fan working ring clamping methods involve multi-point support and corresponding multi-point clamping, with additional positioning points on the maximum outer diameter. This clamping method applies all clamping force to the fan working ring, and the supports have suspended positions, resulting in significant clamping deformation. After normal clamping, the fan working ring's circular runout can reach 1mm. Furthermore, the machining method for the decorative groove involves full-circle milling, with radial layering. During milling, the wall thickness cannot be measured, making it impossible to adjust the machining process based on measurements to ensure the wall thickness meets specifications. The machining method for the precision holes in the double-layer annular grooves involves first drilling a hole flush with the groove, then drilling through both layers, and finally machining to the desired position with a reamer. Because the two layers of annular grooves are spaced a certain distance apart, this machining method results in uneven tool stress and inconsistent machining allowances, easily leading to tool wobble and breakage, causing the precision hole diameter to exceed tolerances, resulting in unqualified machining and a low pass rate. In conclusion, using existing fan working ring groove clamping and machining methods results in a low pass rate and high quality risk for the fan working ring. Summary of the Invention

[0004] This invention provides a method for clamping and machining the slots in the working ring of an aero-engine fan, in order to solve the technical problems of low pass rate and high quality risk in existing methods for machining fan working rings.

[0005] According to one aspect of the present invention, a method for clamping and machining the slots of a fan working ring for an aero-engine is provided. This method clamps and fixes the fan working ring, and machines precision holes in the lace groove and double-layer annular groove on the fan working ring, while ensuring that the diameter of the precision holes and the wall thickness of the fan working ring are both within acceptable limits. The clamping and machining method specifically includes the following steps: A) Pressing and fixing the fan working ring onto the precision hole machining station; first, using a first submerged drill cutter to countersink the upper annular groove of the fan working ring; then, using a drill bit to enlarge the countersinked hole and drill to the lower annular surface of the fan working ring; then, using a second submerged drill cutter to... A) Drill through the double-layer annular groove of the working ring, and finally use a reamer to machine it into place to complete the machining of the precision hole; B) Design and manufacture a special fixture to support the entire surface of the fan working ring, and use a cover plate to press it tight, while performing full-circumferential outer circle positioning, and angular positioning through precision holes to press and fix the fan working ring on the lace groove machining station; C) Perform full-circumferential segmented milling of the lace groove to be machined on the fan working ring. After each segment of the lace groove is milled, first measure the wall thickness of the fan working ring, then adjust the tool compensation according to the wall thickness of the fan working ring, and then perform the milling of the next segment of the lace groove.

[0006] As a further improvement to the above technical solution:

[0007] Furthermore, the special fixture includes a base for supporting the fan working ring from the bottom to provide full-surface support for the lower end face of the fan working ring, a positioning step disposed on the base for fitting around the fan working ring to provide full-circle outer-circle positioning for the fan working ring, a cover plate disposed on the upper end face of the fan working ring, a clamping member disposed on the base and connected to the cover plate for rotating downward to press the cover plate to press the cover plate tightly against the fan working ring, and a positioning pin disposed on the base for inserting and engaging with a precision hole on the fan working ring to provide angular positioning for the fan working ring.

[0008] Furthermore, the positioning gap for the full-circle outer circle positioning in step B is 0.03mm-0.05mm.

[0009] Furthermore, the base is provided with multiple measuring grooves that correspond one-to-one with the multi-segment lace grooves to be processed.

[0010] Furthermore, the clamping component includes a connecting screw rod centrally fixed on the base and passing through the cover plate, a pressure block sleeved on the connecting screw rod and pressing downward against the cover plate, and a clamping nut threadedly connected to the free end of the connecting screw rod and pressing downward against the pressure block.

[0011] Further, in step A, the cutting length of the first submerged drill cutter is 4-6 mm and the overhang is 20-30 mm; and / or the cutting length of the drill bit is 6-8 mm and the overhang is 25-35 mm; and / or the cutting length of the second submerged drill cutter is 8-10 mm and the overhang is 30-40 mm; and / or the cutting length of the reamer is 8-10 mm and the overhang is 30-40 mm.

[0012] Further, the first step is to use a first submerged milling cutter to countersink the upper annular groove of the fan working ring, with a drilling depth of 3.5mm-4.5mm.

[0013] Further, the hole in the countersunk is enlarged with a drill bit and drilled into the lower ring surface of the fan working ring. The drilling depth of the drill bit on the lower ring surface of the fan working ring is 1-2 mm.

[0014] Furthermore, step B also includes the step of performing a dial indicator check on the radial side of the fan working ring before and after compression to obtain the amount of compression deformation of the radial side of the fan working ring before and after compression, so as to adjust the compression force according to the amount of compression deformation.

[0015] Furthermore, the step of pressing and fixing the fan working ring onto the precision hole machining station also includes the step of performing a dial indicator check on the axial end face of the fan working ring before and after pressing to obtain the amount of pressing deformation of the axial end face of the fan working ring before and after pressing, so as to adjust the pressing force according to the amount of pressing deformation.

[0016] The present invention has the following beneficial effects:

[0017] The present invention discloses a method for clamping and machining the slot of a fan working ring for an aero-engine. First, the fan working ring is pressed and fixed onto a precision hole machining station. Then, a first submerged drill bit is used to countersink the upper ring groove of the fan working ring to allow the submerged drill bit to be used for machining within the ring groove, achieving calibrated positioning of the precision hole's circumferential position. This also prevents uneven force on the drill bit during machining, which could lead to shaking or tool breakage. Next, the countersinked hole is enlarged with a drill bit and drilled to the lower ring surface of the fan working ring to prevent chipping and deviation during submerged drill bit machining. After considering factors such as spacing, a second submerged drill bit is used to drill through the double-layer annular groove of the fan working ring to prevent uneven force distribution during drill bit processing, which could lead to shaking or tool breakage. Finally, a reamer is used to machine the precision hole, ensuring that the hole diameter meets the required specifications. The entire machining process employs alternating submerged drill bits and drill bits to effectively avoid the drawbacks of each method, thus guaranteeing machining quality and significantly improving the precision hole machining pass rate. A special fixture is designed and manufactured to support the entire fan working ring. The fan working ring is secured by a cover plate to increase the contact area between the special fixture and the support and pressing surface, thus ensuring uniform force distribution and significantly reducing compression deformation. Simultaneously, full-circumferential outer-circumference positioning limits the deformation space of the fan working ring, further minimizing compression deformation. Angular positioning is achieved through precision holes to firmly secure the fan working ring to the lace groove machining station. The lace groove to be machined on the fan working ring is milled in segments along the circumferential direction. During milling, the wall thickness of the fan working ring can be measured. After each segment of the lace groove is milled, the wall thickness of the fan working ring is measured first, and then the tool compensation is adjusted according to the wall thickness before proceeding to the next segment of the lace groove, ensuring that the wall thickness meets the requirements. This solution optimizes and improves the machining method of the precision holes on the fan working ring, the clamping fixtures for the lace groove, and the machining method. Compared with existing technologies, it significantly improves the pass rate, reduces quality risks, and is highly practical, suitable for widespread promotion and application.

[0018] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0019] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 This is a flowchart of a preferred embodiment of the machining method for clamping and machining the working ring slot of an aero-engine fan.

[0021] Figure 2This is a partial structural diagram of the fan working ring in the preferred embodiment of the fan working ring slot clamping and machining method for an aero-engine according to the present invention;

[0022] Figure 3 yes Figure 2 A cross-sectional view of the AA section of the fan working ring shown;

[0023] Figure 4 yes Figure 2 A cross-sectional view of the BB portion of the fan working ring shown;

[0024] Figure 5 This is a schematic diagram of the structure of the special fixture in the preferred embodiment of the machining method for clamping the working ring slot of an aero-engine fan;

[0025] Figure 6 This is a cross-sectional view of the special fixture in the machining method for clamping the working ring slot of an aero-engine fan according to a preferred embodiment of the present invention.

[0026] Legend:

[0027] 100. Base; 200. Positioning step; 300. Cover plate; 400. Clamping part; 500. Positioning pin. Detailed Implementation

[0028] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0029] Figure 1 This is a flowchart of a preferred embodiment of the machining method for clamping and machining the working ring slot of an aero-engine fan. Figure 2 This is a partial structural diagram of the fan working ring in the preferred embodiment of the fan working ring slot clamping and machining method for an aero-engine according to the present invention; Figure 3 yes Figure 2 A cross-sectional view of the AA section of the fan working ring shown; Figure 4 yes Figure 2 A cross-sectional view of the BB portion of the fan working ring shown; Figure 5 This is a schematic diagram of the structure of the special fixture in the preferred embodiment of the machining method for clamping the working ring slot of an aero-engine fan. Figure 6 This is a cross-sectional view of the special fixture in the machining method for clamping the working ring slot of an aero-engine fan according to a preferred embodiment of the present invention.

[0030] like Figures 1-4As shown, the method for clamping and machining the fan working ring groove of an aero-engine in this embodiment is used to clamp and fix the fan working ring and to machine precision holes in the lace groove and double-layer ring groove on the fan working ring, while ensuring that the diameter of the precision holes and the wall thickness of the fan working ring are qualified. The clamping and machining method specifically includes the following steps: A. Press and fix the fan working ring on the precision hole machining station. First, use a first submerged drill cutter to countersink the upper ring groove of the fan working ring, then use a drill bit to enlarge the countersinked hole and drill to the lower ring surface of the fan working ring. Then, use a second submerged drill cutter to machine the double-layer ring groove of the fan working ring. A) Drill through the ring groove and finally machine it into place with a reamer to complete the machining of the precision hole; B) Design and manufacture a special fixture to support the entire fan working ring and use a 300mm cover plate to press it in place. At the same time, perform full-circumference outer circle positioning and angular positioning through precision holes to press and fix the fan working ring on the lace groove machining station; C) Perform full-circumference segmented milling of the lace groove to be machined on the fan working ring. After each segment of the lace groove is milled, first measure the wall thickness of the fan working ring, then adjust the tool compensation according to the wall thickness of the fan working ring, and then perform the milling of the next segment of the lace groove.Specifically, the method for clamping and machining the slot of the working ring of an aero-engine fan according to the present invention firstly presses and fixes the fan working ring on a precision hole machining station. Then, a first submerged drill bit is used to countersink the upper ring groove of the fan working ring to allow the submerged drill bit to be used for machining within the ring groove hole, and to achieve calibration and positioning of the circumferential position of the precision hole. This also prevents uneven force on the drill bit during machining, which could lead to shaking or tool breakage. Next, the countersinked hole is enlarged with a drill bit and drilled to the lower ring surface of the fan working ring to prevent chipping of the submerged drill bit during machining. To prevent issues such as deviation, a second submerged drill bit is used to drill through the double-layer annular groove of the fan working ring. This prevents uneven force distribution during drill bit processing, which could lead to shaking or tool breakage. Finally, a reamer is used to machine the precision hole, ensuring that the hole diameter meets specifications. The entire machining process employs alternating submerged drill bits and drill bits to effectively mitigate the drawbacks of each method, thus guaranteeing machining quality and significantly improving the precision hole machining pass rate. A special fixture is designed and manufactured to perform surface finishing of the fan working ring. The fan working ring is supported and clamped with a 300mm cover plate to increase the contact area between the special fixture and the support and clamping surface, thereby ensuring uniform force distribution on the fan working ring and significantly reducing its clamping deformation. Simultaneously, full-circumferential outer-circumference positioning is performed to limit the deformation space of the fan working ring, further reducing clamping deformation. Angular positioning is achieved through precision holes to clamp and fix the fan working ring to the lace groove machining station. The lace groove to be machined on the fan working ring is then milled in segments along the entire circumferential direction. Therefore, the wall thickness of the fan working ring can be measured during the milling process. After each section of the decorative groove is milled, the wall thickness of the fan working ring is measured first, and then the tool compensation is adjusted according to the wall thickness before proceeding with the milling of the next section of the decorative groove, thus ensuring that the wall thickness is within acceptable limits. This solution optimizes and improves the machining method of the precision holes on the fan working ring, as well as the clamping fixture and machining method of the decorative groove. Compared with existing technologies, it greatly improves the pass rate, reduces quality risks, and is highly practical, suitable for widespread promotion and application. It should be understood that the width of the annular groove is 2.5mm, which is smaller than the diameter of the precision hole. When a drill bit is used to machine a precision hole with an annular groove and a diameter smaller than the tool diameter, uneven force may cause shaking and tool breakage. It should also be understood that when a submerged drill end mill is used to machine a precision hole without a bottom hole or groove on the surface, chipping and deviation may occur. Optionally, the acceptable diameter of the precision hole is φ3.973 (+0.012, 0). In step A, the upper ring groove of the fan working ring is first countersunk using a φ3 first submerged drill bit, then the countersunk hole is enlarged using a φ3.5 drill bit and drilled to the lower ring surface of the fan working ring. Then, the double-layer ring groove of the fan working ring is drilled through using a φ3.9 second submerged drill bit, and finally, the precision hole is machined to the required position using a φ3.973 reamer. Optionally, the acceptable wall thickness of the fan working ring is 3 (0, -0.5).

[0031] like Figure 5 and Figure 6 As shown, in this embodiment, the special fixture includes a base 100 for supporting the fan working ring from the bottom to provide full-surface support for the lower end face of the fan working ring; a positioning step 200 disposed on the base 100 for fitting around the fan working ring to position the outer circle of the fan working ring; a cover plate 300 for covering the upper end face of the fan working ring; a clamping member 400 disposed on the base 100 and connected to the cover plate 300 for rotating downwardly pressing the cover plate 300 to press the cover plate 300 tightly against the fan working ring; and a positioning pin 500 disposed on the base 100 for inserting into a precision hole on the fan working ring to position the fan working ring angularly. Specifically, after the special fixture is fixed on the lace groove processing station, the base 100 supports the lower end face of the fan working ring, and the locating pin 500 angularly positions the fan working ring. Then, the locating step 200 positions the fan working ring around its entire outer circle. Finally, the cover plate 300 and the clamping part 400 work together to clamp the fan working ring, thereby fixing the fan working ring on the lace groove processing station.

[0032] like Figure 5 and Figure 6 As shown, in this embodiment, the positioning gap for the full-circle outer circle positioning in step B is 0.03mm-0.05mm. Specifically, when the positioning gap for the full-circle outer circle positioning is 0.03mm-0.05mm, the clamping difficulty of the fan working ring is appropriate, and the compression deformation of the fan working ring can be effectively reduced; when the positioning gap for the full-circle outer circle positioning is less than 0.03mm, the clamping difficulty of the fan working ring will be greatly increased; when the positioning gap for the full-circle outer circle positioning is greater than 0.05mm, the compression deformation of the fan working ring is large, and the processing quality is low.

[0033] In this embodiment, the base 100 is provided with multiple measuring slots that correspond one-to-one with the multiple lace grooves to be processed. Specifically, after each lace groove is processed, the wall thickness of the fan working ring is measured through the measuring slots, so as to adjust the tool compensation according to the wall thickness to control the wall thickness and thus ensure that the wall thickness dimension is qualified.

[0034] like Figure 5 and Figure 6As shown, in this embodiment, the clamping member 400 includes a connecting screw rod centrally fixed on the base 100 and passing through the cover plate 300, a pressure block sleeved on the connecting screw rod and abutting downward against the cover plate 300, and a clamping nut threaded to the free end of the connecting screw rod and pressing downward against the pressure block. Specifically, after the fan working ring is arranged on the base 100, the cover plate 300 is sleeved on the connecting screw rod and presses against the upper end face of the fan working ring. Then, the pressure rod is sleeved on the connecting screw rod and abuts downward against the cover plate 300. Finally, the clamping nut is screwed into the free end of the connecting screw rod so that the clamping nut presses downward against the pressure block to press against the pressure plate, thereby achieving the clamping and fixing of the fan working ring.

[0035] In this embodiment, in step A, the cutting length of the first embedded drill end mill ranges from 4-6 mm, and the overhang ranges from 20-30 mm. Specifically, when the cutting length of the first embedded drill end mill is 4-6 mm and the overhang range is 20-30 mm, it ensures that the first embedded drill end mill can drill and mill to the desired depth, and the rigidity of the tool is appropriate. When the cutting length of the first embedded drill end mill is less than 4 mm or the overhang range is less than 20 mm, the first embedded drill end mill cannot drill and mill to the desired depth. When the cutting length of the first embedded drill end mill is greater than 6 mm or the overhang range is greater than 30 mm, the rigidity of the tool is poor, it is easily damaged, and the machining quality is low.

[0036] In this embodiment, in step A, the cutting edge length of the drill bit ranges from 6-8 mm, and the overhang ranges from 25-35 mm. Specifically, when the cutting edge length of the drill bit is 6-8 mm and the overhang range is 25-35 mm, it ensures that the drill bit can reach the desired drilling and milling position, and the rigidity of the tool is appropriate. When the cutting edge length of the drill bit is less than 6 mm or the overhang range is less than 25 mm, the drill bit cannot reach the desired drilling and milling position. When the cutting edge length of the drill bit is greater than 8 mm or the overhang range is greater than 35 mm, the rigidity of the tool is poor, it is easily damaged, and the machining quality is low.

[0037] In this embodiment, in step A, the cutting length of the second submerged drill cutter ranges from 8-10mm, and the overhang ranges from 30-40mm. Specifically, when the cutting length of the second submerged drill cutter is 8-10mm and the overhang range is 30-40mm, it ensures that the second submerged drill cutter can drill and mill to the desired depth, and the tool rigidity is appropriate. When the cutting length of the second submerged drill cutter is less than 8mm or the overhang range is less than 30mm, the second submerged drill cutter cannot drill and mill to the desired depth. When the cutting length of the second submerged drill cutter is greater than 10mm or the overhang range is greater than 40mm, the tool rigidity is poor, it is easily damaged, and the machining quality is low.

[0038] In this embodiment, in step A, the cutting length of the reamer ranges from 8-10mm, and the overhang ranges from 30-40mm. Specifically, when the cutting length of the reamer is 8-10mm and the overhang range is 30-40mm, it ensures that the reamer is machined to the required position and that the tool rigidity is appropriate. When the cutting length of the reamer is less than 8mm or the overhang range is less than 30mm, the reamer cannot machine to the required position. When the cutting length of the φ3.973 reamer is greater than 10mm or the overhang range is greater than 40mm, the tool rigidity is poor, it is easily damaged, and the machining quality is low.

[0039] like Figure 1 As shown, in this embodiment, the first step involves using a φ3 submerged drill bit to countersink the upper annular groove of the fan working ring to a depth of 3.5mm-4.5mm. Specifically, when the drilling depth is 3.5mm-4.5mm, the first submerged drill bit can countersink the upper annular groove of the fan working ring without drilling through the upper ring. When the drilling depth is less than 3.5mm, the first submerged drill bit cannot countersink the upper annular groove, affecting subsequent drill bit processing. When the drilling depth is greater than 4.5mm, the first submerged drill bit may drill through the upper ring, causing the submerged drill bit to chip and deviate. It should be understood that the groove depth in the fan working ring is 4.5mm.

[0040] like Figure 1 As shown, in this embodiment, the next step involves enlarging the hole in the countersunk cutter with a drill bit and drilling into the lower ring surface of the fan working ring. The drilling depth of the drill bit on the lower ring surface of the fan working ring is 1-2 mm. Specifically, when the drilling depth of the drill bit on the lower ring surface of the fan working ring is 1-2 mm, it provides a good machining environment for the subsequent second embedded drill bit and also avoids the drill bit from drilling into the lower ring groove of the fan working ring, which could lead to uneven force and issues such as shaking and tool breakage.

[0041] like Figure 1 As shown, in this embodiment, step B further includes a step of performing a dial indicator check on the radial side of the fan working ring before and after clamping to obtain the clamping deformation amount of the radial side of the fan working ring before and after clamping, so as to adjust the clamping force according to the clamping deformation amount. Specifically, the clamping deformation amount is obtained by dial indicator check, and then the clamping force is adjusted according to the clamping deformation amount to ensure that the clamping deformation amount after clamping and fixing of the fixture is appropriate, so as to ensure the processing quality. Optionally, when the clamping deformation amount is not greater than 0.05, the clamping deformation amount of the lace groove on the fan working ring is appropriate.

[0042] like Figure 1As shown in this embodiment, the step of pressing and fixing the fan working ring onto the precision hole machining station further includes the step of performing a dial indicator check on the axial end face of the fan working ring before and after pressing to obtain the amount of pressing deformation of the axial end face of the fan working ring before and after pressing, so as to adjust the pressing force according to the amount of pressing deformation. Specifically, the amount of pressing deformation is obtained by dial indicator check, and then the pressing force is adjusted according to the amount of pressing deformation to ensure that the amount of pressing deformation after clamping and fixing is appropriate, so as to ensure the machining quality. Optionally, when the amount of pressing deformation is not greater than 0.1, the amount of pressing deformation of the precision hole machining on the fan working ring is appropriate.

[0043] 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 fan working ring slot hole clamping machining method for fan working ring clamping and fixing, and machining precision holes in the lace slot and double-layer ring slot on the fan working ring, while ensuring that the hole diameter size of the precision hole is qualified and the wall thickness size of the fan working ring is qualified, characterized in that, The clamping machining method specifically comprises the following steps: ​ A, the fan working ring is tightly fixed on the precision hole machining station, first, the first buried drill milling cutter is used to mill the upper ring groove of the fan working ring, then the drilled hole is reamed by the drill, and drilled to the lower ring surface of the fan working ring, then the double-layer ring groove of the fan working ring is drilled by the second buried drill milling cutter, finally, the reamer is processed in place to complete the machining of the precision hole; B, a special fixture is designed and manufactured, the fan working ring is supported and relied on the whole surface by the special fixture, and the cover plate (300) is used to tightly press, at the same time, the whole circle outer circle positioning is carried out, and the angular positioning is realized through the precision hole, so that the fan working ring is tightly fixed on the lace groove machining station; C, the lace groove to be machined on the fan working ring is milled in the circumferential direction, wherein after each section of lace groove is milled, the wall thickness of the fan working ring is measured, then the tool compensation is adjusted according to the wall thickness of the fan working ring, and then the milling of the next section of lace groove is carried out; The special fixture comprises a base (100) for supporting the fan working ring from the bottom to support the lower end surface of the fan working ring, a positioning step (200) disposed on the base (100) for sleeving on the fan working ring to position the fan working ring in the whole circle outer circle, a cover plate (300) for covering on the upper end surface of the fan working ring, a pressing member (400) disposed on the base (100) and connected with the cover plate (300) for rotating downward to press the cover plate (300) to tightly press the fan working ring, and a positioning pin (500) disposed on the base (100) for inserting into the precision hole on the fan working ring to angularly position the fan working ring; The positioning gap of the whole circle outer circle positioning in step B is 0.03mm-0.05mm; A plurality of measurement grooves are formed on the base (100) corresponding to the plurality of sections of lace grooves to be machined; In step A, the length of the blade of the first buried drill milling cutter is 4-6mm, and the overhang length is 20-30mm; The length of the blade of the drill is 6-8mm, and the overhang length is 25-35mm; The length of the blade of the second buried drill milling cutter is 8-10mm, and the overhang length is 30-40mm; The length of the blade of the reamer is 8-10mm, and the overhang length is 30-40mm.

2. The method of claim 1, wherein, The pressing member (400) comprises a connecting screw rod fixedly disposed on the base (100) and penetrating the cover plate (300), a pressing block sleeved on the connecting screw rod and abutting against the cover plate (300) downward, and a pressing nut threadedly connected with the free end of the connecting screw rod and pressing the pressing block downward.

3. The method of claim 1 or 2, wherein the method further comprises: In the step of first using the first buried drill milling cutter to mill the upper ring groove of the fan working ring, the drilling depth is 3.5mm-4.5mm.

4. The method of claim 1-2, wherein, In the step of then using the drill to ream the drilled hole and drill to the lower ring surface of the fan working ring, the drilling depth of the drill on the lower ring surface of the fan working ring is 1-2mm.

5. The method of claim 1-2, wherein, In step B, the radial side surface of the fan working ring before and after being tightly pressed is also measured to obtain the tight pressing deformation of the radial side surface of the fan working ring before and after being tightly pressed, so that the tight pressing force is adjusted according to the tight pressing deformation.

6. The method of claim 1-2, wherein, The step of pressing and fixing the fan working ring on the precision hole processing station further comprises the step of checking the axial end face of the fan working ring before and after pressing, so as to obtain the pressing deformation of the axial end face of the fan working ring before and after pressing, and to adjust the pressing force according to the pressing deformation.

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