Method and tooling for machining complex casings of an aeroengine

Abstract

A method for processing complex engine casing, high-precision blade hole processing is carried out on the casing body or the casing body boss, using tooling and numerical control machine tool, the tooling includes first tooling bottom plate, second tooling bottom plate, positioning pin, pressing device, the first tooling bottom plate is a circular plate and is fixed on the workbench of numerical control machine tool, the second tooling bottom plate is also a circular plate and covers the first tooling bottom plate, the pressing device fixes the circular bottom of the casing body on the second tooling bottom plate, more than three positioning pins are arranged between the first tooling bottom plate and the second tooling bottom plate, the center of the first tooling bottom plate and the second tooling bottom plate is provided with a central positioning pin, a plurality of small holes are uniformly arranged on the outer side of the circular plate of the second tooling bottom plate along the circumference, and the distribution angle of the small holes on the circumference corresponds to the distribution angle of the cylindrical side blade hole of the casing body;A plurality of fixed holes with the same hole diameter as the small hole diameter of the outer side of the second tooling bottom plate are arranged on the first tooling bottom plate as positioning pin holes.

Description

TECHNICAL FIELD

[0001] The present application relates to an aero-engine, in particular to a tooling and processing method of a complex aero-engine casing with a multi-layer multi-shaped boss and a multi-layer installation of different types of blades. BACKGROUND

[0002] The aero-engine casing structure is complex, the processing precision is high, and the features are numerous, especially the casing with bosses and blade holes of different angles, which requires higher machine tools. The existing technology for processing this part must be completed by four-axis or five-axis machining center (machine tool).

[0003] The object of processing is the casing provided with bosses and holes for installing multiple sets of static blades. The precision of the blade hole is high, especially the angle of the hole (collimation) is higher. Otherwise, the error will be amplified and affect the installation precision of the static blade. Since the number of holes on the casing is large, there are multiple rows of holes (uniform or non-uniform) on the cylindrical surface (including conical and honeycomb type) of the casing, even hundreds of them. The working hours of five-axis machining center will be very long. Due to various factors, it is extremely likely that the overall workpiece will be scrapped (cannot be repaired) due to the precision of individual holes not meeting the standard. Therefore, it is urgent to invent a simple three-axis numerical control machine tool to replace high-precision four-axis and five-axis machine tools to complete the processing of aero-engine casings, especially casings for installing multiple sets of static blades.

[0004] The working hours of high-precision four-axis and five-axis machine tools are high and the processing time is extremely long. Four-axis and five-axis machine tools are prone to errors during long-time processing. Due to the many bosses and holes on the circumference (side surface) of the aero-engine casing and some other features, the turret needs to be rotated for processing during processing. However, long-time rotation processing of four-axis and five-axis machine tools is prone to errors and has poor repeatability. The bosses and holes of the aero-engine casing have very high precision requirements, and the precision of the blade hole on the casing is as high as 0-+0.012mm. The angular error of the blade hole is higher, especially the domestic four-axis and five-axis machine tools are difficult to complete the processing of aero-engine casings after several years of operation. In this case, it is also urgent to invent a simple three-axis numerical control machine tool to replace high-precision four-axis and five-axis machining centers to complete the processing of aero-engine casings.

[0005] The complexity and difficulty of processing the aero-engine casing itself: the aero-engine casing, with a multi-layer multi-shaped boss and a multi-layer installation of different types of blades, is a cylindrical (and conical and honeycomb type composite structure) complex casing provided with bosses and holes. The processing mainly includes the processing of circular high-precision blade hole bosses, the processing of high-precision blade holes, and the processing of blade hole counterbores.

[0006] The circular high-precision blade hole on the casing is generally arranged on the boss of the casing, a ring of bosses are connected in series, and a reinforcing rib is arranged between two bosses. The boss mainly plays a role in strengthening the strength and rigidity of the casing and reducing the weight of the casing. The bosses are numerous and dense, and the corners between the bosses are also small, which increases the difficulty of processing, increases the processing time, increases the use of tools, and reduces the work efficiency. The processing precision of the blade hole is higher. If the precision of the hole is high enough, the boss milling processing is reliable.

[0007] The design of the high-precision blade hole is to cooperate with the mounting cylindrical surface of the blade root. The gap between the two is very small, generally 0.02-0.03mm, and the precision of the blade hole is generally 0-+0.012mm. Such high precision requirements increase the difficulty of processing, and it is particularly important to seek a reasonable processing method and arrange a reasonable processing technology. Especially, the hole quantity is extremely large, and the diameter may also be different. In short, there is no efficient processing method for such workpieces at present.

[0008] The prior art CN2016105438295 discloses a method for machining an aero-engine casing by a five-axis linkage milling and machining center. Six pairs of annularly and uniformly distributed handles are connected with and fixed to the outer side pressing mechanism and the inner side pressing mechanism, and are fixed to the outer side pressing support disc and the inner side pressing support disc, respectively. The outer side pressing support disc and the inner side pressing support disc are connected and fixed to the base through six columns, respectively. Each of the six columns has a bottom pressing mechanism between the base. The upper end of the inner side column is connected with an upper cover plate. The invention is processed by the clamping device and the adjustable mechanism of the inner wall and the outer wall. SUMMARY

[0009] The purpose of the present application is to provide a new processing technology, improve the processing efficiency, reduce the processing cost, control the deformation of the casing, and ensure the design precision. In particular, the tooling and method for processing a complex aero-engine casing by a simple numerical control machine tool. Especially, the precision processing of drilling and boring multiple holes on the casing (or on the boss of the casing), the hole collimation degree is high, and the processing efficiency is ensured, and the cost is greatly saved. There is no need to use a four-axis or five-axis machining center (machine tool) to mill holes on the engine casing, the processing precision is higher, and the boss processing and precise hole processing with different angles are provided.

[0010] The technical scheme of the present application is a machining method for a complex casing of an aero-engine, the casing with thin walls has multiple sets of multiple blade holes and bosses, comprising machining of the casing body or the boss of the (machined) casing body and machining of the high-precision blade holes on the boss: the diameter of the blade hole is D8-D18 (0-+0.012), and the deepest set of holes is 65 mm; the method of drilling and boring is adopted to machine the blade hole to a high standard; the machining of the high-precision blade hole on the casing body or the boss of the casing body adopts a tooling and a (simple) numerical control machine tool, the tooling comprises a first tooling base plate 1, a second tooling base plate 2, a taper pin 3, a positioning pin 4, and a pressing device 5, the first tooling base plate is a circular plate and is fixed on the worktable of the numerical control machine tool, the second tooling base plate 2 is also a circular plate and covers the first tooling base plate, the pressing device 5 fixes the circular bottom of the casing body on the second tooling base plate 2, more than three fixing devices are arranged between the first tooling base plate 1 and the second tooling base plate 2, the center of the first tooling base plate 1 and the second tooling base plate 2 is provided with a central positioning pin, the second tooling base plate can rotate around the central positioning pin (especially a taper pin), a plurality of small holes are uniformly arranged on the outer side of the circular plate of the second tooling base plate, and the distribution angle of the small holes on the circumference corresponds to the distribution angle of the cylindrical side blade holes of the casing body; a plurality of fixing holes with the same hole diameter as the small holes on the outer side of the circular plate of the second tooling base plate are arranged on the first tooling base plate as pin holes, and the positioning pin is fixed by penetrating the small holes of the first tooling base plate and the second tooling base plate. The positioning pin is matched with the fixing hole (preferably in a tight fit).

[0011] A mechanism for driving the second tooling base plate to rotate is arranged, that is, threads or teeth are arranged on the side surface of the second tooling base plate, a matching lead screw or worm is engaged with the threads or teeth, and adjustment of the rotation of the lead screw or worm can adjust the rotation of the second tooling base plate.

[0012] A plurality of circumferences (uniformly distributed small holes) can be arranged (four circumferences in the embodiment), and each circumference (hole) corresponds to the positioning of a set of blade holes on the casing body; the present application converts the positioning of the drilling perpendicular to the casing body into the positioning on the planar circular plate tooling, which is easier to precisely machine the uniformly distributed small holes (which can be machined by a precision numerical control drill + precision grinding or boring), and the small holes can be distributed at equal intervals and correspond to the equal-interval blade mounting holes on the casing body or the non-equal-interval blade (mounting) holes.

[0013] A groove can be arranged on the contact surface between the second tooling base plate and the casing body, which matches the flange ring or the circular ring of the casing body, and the flange ring can have a hole, which is fixed with the hole on the second base plate by a latch, and is fixed with the pressing device on the second tooling base plate.

[0014] The machining of the high-precision blade holes on the casing body or boss can be performed in advance, that is, after the turning of the outer side and the inner side of the casing body is completed, only a 0.2-2mm allowance is left, and the machining of the holes is performed after the bottom ring or the bottom ring flange of the casing body reaches the precision.

[0015] The tooling and the numerical control machine tool machine the blade holes on the casing body 6; the first tooling bottom plate 1 and the second tooling bottom plate 2 can be fixed on the workbench of the numerical control machine tool at the same time for machining; that is, the taper pin 3 passes through the conical hole below the first tooling bottom plate 1) to fix the first tooling bottom plate 1) on the machine tool workbench together with the taper pin 3.

[0016] By using the present application, drilling and boring machining can be performed by using a (simple) numerical control machine tool; the casing body is accurately fixed; even when there are several circles of blade holes, the first tooling bottom plate is a circular plate and is fixed on the workbench of the numerical control machine tool; a cylindrical pin is inserted into the positioning pin hole on the second tooling bottom plate 2 and the pin hole of the first tooling bottom plate 1 at the same time to make the angular orientation consistent; when the first tooling bottom plate 1 is placed and fixed on the machine tool workbench, the angular orientation of the drilling angle has been already aligned; the second tooling bottom plate 2 and the casing body can be pressed to perform drilling and cutting machining; as long as a drill or a boring tool is used for cutting in the Z-axis direction (any drilling or boring angle is accurately aligned), after a group (one) of machining is completed, the second tooling bottom plate is directly rotated or the second tooling bottom plate is rotated through the threaded holes on the side surface of the second tooling bottom plate, a screw rod, and the second tooling bottom plate 2 is driven to rotate around the taper pin 3; when the next group (one) of angles is reached, the cylindrical pin is inserted to fix the second tooling bottom plate 2, and the cutting machining can be performed again; and so on; after one circle of holes is completed, the position of the workbench in the axial direction is adjusted to align with the machining position of the second circle of blade holes, and the machining of the second circle of blade holes is performed until the machining of the holes with different angles in four circles (for example, one circle or more circles of holes can be implemented) is completed. Milling machining of the boss can also be performed at the same time. A special working tool (head) is used for milling machining of the boss, and the boss must be machined by programming.

[0017] Matching circular convex tracks and grooves are arranged on the contact surface of the first tooling bottom plate 1 and the second tooling bottom plate 2; the same multiple circles of holes are machined on the first tooling bottom plate as on the second tooling bottom plate, so that under this condition, the insertion hole of the fixing pin can make any machining position be able to fix the workpiece. The multiple circles of holes are generally uniformly distributed.

[0018] Installation: 1. The taper pin 3 passes through the conical hole below the first tooling bottom plate 1) to fix the first tooling bottom plate 1) on the machine tool workbench together with the taper pin 3, and the angular orientation is aligned. The taper pin is the pin shaft around which the second bottom plate rotates.

[0019] 2. The second tooling bottom plate 2 is placed above the first tooling bottom plate 1 by passing through the taper pin 3; during machining, the second tooling bottom plate 2 is fixed on the machine tool workbench by using a pressing device.

[0020] 3. Put the casing body into the positioning groove of the second fixture base plate, insert 4 (positioning pin) into the specified pin hole of 6 (casing body) and the pin hole on the second fixture base plate 2, so that 6 (casing body) and the second fixture base plate can keep concentricity and angular position, and 1 (fixture base plate 1) and the second fixture base plate can keep concentricity through 3 (tapered pin).

[0021] 4. Fix 6 (casing body) on the second fixture base plate 2 with 5 (pressing device).

[0022] The second fixture base plate is provided with small holes on the outer side of the circular plate, and the distribution angle of the small holes on the circumference corresponds to the distribution angle of the blade hole of the cylindrical side of the casing body; a plurality of (four circles in the embodiment) circumferences (small holes are uniformly distributed) can be provided, and each circumference (hole) corresponds to the positioning of a circle of blade holes on the casing body;

[0023] The machining method of the high-precision blade hole on the boss after the positioning of the fixture is as follows: 1) a D10 center drill is used for pre-drilling to serve as centering; the bevel of the center drill is drilled to a depth of 7 mm, so that the subsequent drill hole will not swing.

[0024] 2) a D8 carbide drill bit is used to drill a hole and remove the excess amount in the hole, so that the hole is drilled through.

[0025] 3) a D12.7 carbide drill bit is used to expand the hole, further remove the excess amount, and leave a single-sided 0.15 mm excess amount for fine boring.

[0026] 4) a boring tool suitable for a hole diameter D13 is used for boring, and an inner-cooled boring tool rod is selected. The machining parameters are shown in the embodiment.

[0027] The machining of the blade hole boss is as follows: 1) a plurality of uniform points on the outer periphery of the boss contour at the corners on both sides of the blade hole boss are pre-drilled, and a drill bit with a diameter of 11.5 is used to drill the hole, leaving a single-sided excess amount of 0.25 mm, and the effective depth controls the actual depth of the boss but leaves an excess amount of 0.5 mm;

[0028] 2) then a D25R1 blade milling cutter is used to rough-mill the tool path, leaving an excess amount of 0.2 mm, a D12R1 carbide milling cutter is used to remove the excess amount of the tool path, leaving an excess amount of 0.1 mm, and finally a D10R5 ball milling cutter is used for the finish machining of the profile and the circular high-precision blade hole boss of the casing body 6; after the machining of the circular high-precision blade hole boss is completed, the hole can also be drilled.

[0029] Beneficial effects: The casing structure of an aero-engine is complex, the machining precision is high, and there are many features, especially the casing with bosses and holes of different angles, which requires a higher machine tool. The machining of this piece in the prior art is mostly completed by a four-axis or five-axis machining center (machine tool).

[0030] Due to the structure of the tooling, the processed object casing is provided with a boss, and a hole is bored on the boss for mounting multiple sets of static vane casings, which requires higher accuracy, especially the drilling (processing) hole angle, i.e. the collimation degree, otherwise the error amplification will affect the installation accuracy of the static vane. Since the number of holes on the casing is large, there are multiple rows of holes (uniform or non-uniform) on the cylindrical (conical, bee waist type) side surface of the casing, even hundreds of them, and the working hours of the five-axis machining center will be very long. Due to various factors, it is extremely likely that the overall workpiece will be scrapped (unrepairable) due to the non-standard accuracy of individual holes. The processed object casing is also provided with a boss, and the boss must be precisely bored to ensure that it is aligned, otherwise the error amplification will affect the installation accuracy of the static vane. Therefore, the present application uses a simple three-axis numerical control machine tool to replace high-precision four-axis and five-axis machine tools to complete the machining of the aircraft engine casing, especially the machining of the casing for mounting multiple sets of static vanes.

[0031] The present application has high efficiency and accuracy for vane holes, and the consumption of tools is significantly reduced; during vane hole processing, an internally cooled boring tool bar can be used, so that when deep hole boring is performed, there will be no built-up edge, tool wear, hole wall scratching, size instability, and other quality problems due to the lack of cooling liquid. Overall, the method of the present application can improve processing efficiency, greatly improve metal removal rate, reduce production cost, improve processing continuity, avoid quality accidents caused by frequent tool changes, avoid repeated clamping of workpieces, save time, reduce processing risk, improve processing efficiency, and reduce cost. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Front (front) view of the tooling and the installed casing body;

[0033] Figure 2 For Figure 1 Stereogram of the tooling and the installed casing body after installation;

[0034] Figure 3 For the cross-sectional view of the central positioning pin, i.e. the taper pin 3;

[0035] Figure 4 Front view of the first tooling base plate;

[0036] Figure 5 Front view of the second tooling base plate;

[0037] Figure 6 Cross-sectional view of the positioning pin.

[0038] Figure 7 Stereogram of the machined casing;

[0039] Figure 8 Processing diagram of a circular high-precision vane hole boss.

[0040] Figure 9 Pre-drilling hole diagram at the corner of the vane hole boss.

[0041] Figure 10 Rough machining tool path diagram for the blade milling cutter of D25R1;

[0042] Figure 11 (D12R1 tool path diagram);

[0043] Figure 12 (D10R5 tool path diagram);

[0044] Figure 13 High-precision vane hole machining. DETAILED DESCRIPTION

[0045] The present application is further described below in conjunction with the accompanying drawings:

[0046] Tooling and working principle (see Figure 1 , Figure 2 ). Including the first tooling base plate 1; the second tooling base plate 2; the taper pin 3; the positioning pin 4; the pressing device 5; the machine case body 6;

[0047] Installation: 1. Pass the taper pin 3 through the conical hole below the first tooling base plate 1), fix the first tooling base plate 1) together with the taper pin 3 on the machine tool workbench, and find the angular orientation.

[0048] 2. Place the second tooling base plate 2 above the first tooling base plate 1) through the taper pin 3, and fix the second tooling base plate 2 on the machine tool workbench with the pressing device during machining.

[0049] 3. Place the machine case body) in the positioning groove of the second tooling base plate, insert 4 (positioning pin) into the specified pin hole of 6 (machine case body) and the pin hole on the second tooling base plate 2), so that 6 (machine case body) and the second tooling base plate are concentric, angular position, and 1 (tooling base plate 1) and the second tooling base plate can be kept concentric through 3 (taper pin).

[0050] 4. Fix 6 (machine case body) on the second tooling base plate 2 with 5 (pressing device).

[0051] Working principle: the cylindrical pin is inserted into the positioning pin hole on the second fixture base plate 2) and the pin hole of the first fixture base plate 1 at the same time, so that the angular orientation is consistent, and the angular orientation of the first fixture base plate 1) has been aligned when it is placed on the machine tool table, and the second fixture base plate 2 is pressed to perform cutting processing. After a group of processing is completed, the lead screw is screwed into the threaded hole on the side of the second fixture base plate, and the second fixture base plate 2 is rotated around the tapered pin 3 by pulling the lead screw, and when the next group of angles is reached, the cylindrical pin is inserted to fix the second fixture base plate 2, so that cutting processing can be performed again. In this way, the processing of the bosses and holes with different angles in 4 circles (one circle or more circles) can be completed.

[0052] (1) Overview of each component of the tooling.

[0053] Tapered pin Figure 3 , which keeps the two fixture base plates always concentric and does not move up and down. The tapered pin has an M10 threaded hole above it, which is used to prevent the tapered pin from falling off when the base plate is installed. The size of the tapered pin needs to be matched with the two base plates, so that there is no gap when rotating and the error caused by rotation is reduced.

[0054] Figure 3 The middle tapered pin has a diameter of Φ60 and cooperates with the center of the first and second base plates of the tooling. The center M10 threaded hole is 12 deep, and the hole depth is 13.

[0055] First fixture base plate 1 Figure 4 . First, the angular orientation is aligned through the pin hole on the base plate, and then the base plate is fixed on the machine tool table through the countersunk hole.

[0056] Second fixture base plate 2 Figure 5 . The angular orientation of the four circles of pin holes is positioned, the cartridge is rotated around the tapered pin together with the base plate, so that the bosses and holes with different angles in 4 circles can be processed.

[0057] Positioning pin Figure 6 There can be more than two, and the diameter Φ is the diameter of the pin, and the two numbers are the lengths of the upper and lower sections of the pin. The angular orientation of the two base plates is kept consistent by the positioning pin.

[0058] The invention mechanism of the tooling is as follows:

[0059] 1) Accuracy of the angular orientation of the cartridge.

[0060] The whole circle (multiple rows, four rows of blade holes in the embodiment) of the cartridge requires each hole to be equipped with a round handle static blade, and the round handle static blade is equipped in the blade hole. The blades require to be uniformly directed to the center (i.e. the drilling direction needs to be guaranteed to be directed to the center of the axis of the cartridge, and the collimation of the drilling hole needs to be guaranteed), so the angle consistency of the whole circle of holes is extremely high. Through one-time clamping and debugging, subsequent multi-axis linkage of the machine tool is not required, and the angular position of the processed hole can be well guaranteed, i.e. the accurate angle and the centripetal degree are guaranteed.

[0061] The present tooling can guarantee that the positioning error of the cartridge angle is almost zero through the accurate positioning of the conical pin and the pin hole. The angle of the blade hole of the aircraft engine cartridge and the rotation center of the cartridge body is extremely strict (the actual precision error is not more than 1 second), and the position degree is generally 0.02 mm. If the angle of the blade hole has an error, the angle error of the blade and the deviation of other components will be caused, and the design requirements will not be met.

[0062] 2) Maintain the accuracy of the hole diameter.

[0063] The diameter tolerance of all holes is 0-0.012 mm, and the present method only needs to move the Z-axis of the machine tool (i.e. the direction of the drilling axis or the reaming, boring axis tool), so that the stability of the hole tolerance can be well guaranteed through reaming or boring (or first drilling a small hole for positioning and then reaming or boring).

[0064] The tooling is inserted with the positioning pin and remains stationary, and the hole diameter error caused by the rotation of the rotary table is eliminated, so that the accuracy of the hole diameter processing is improved.

[0065] 3) Reduce the error rate of processing.

[0066] Since the position of the hole is preformed through the tooling, and the positioning of the hole pin shaft is completed for each hole processing, the hole position caused by the machine precision error or failure can be effectively prevented. The complex cartridge is often very valuable as a single piece and cannot be repaired. The scrap of one hole will lead to the scrap of the whole cartridge. The present method can effectively achieve zero error rate and realize stable production of batches of products.

[0067] The cartridge is processed through the tooling. After a group of holes are processed, the second bottom plate is rotated, and the remaining part is continuously processed. Thus, the angular error, positioning error and the like caused by the rotation of the rotary table during processing are reduced. The tool error, program error and the mistakes of the operator caused by the rotation of the rotary table during processing are also reduced.

[0068] Realization of processing of multiple levels of complex cartridges.

[0069] With extremely low equipment investment and stable processing method, the cartridge processing of different complex shapes can be realized. The time consumption of high-end five-axis equipment and high-precision four-axis equipment is avoided, and the present domestic equipment can be completely realized.

[0070] By means of the positioning pin holes of different pitch circles of the tooling bottom plate, machining of multi-level complex casings with different angular orientations can be realized, only by rotating the bottom plate and inserting the positioning pins, which ensures the angular consistency of the casing body and the tooling bottom plate, and makes the machining of multi-level complex casings more easily realized.

[0071] Machining of circular high-precision blade hole boss Figure 8 ).

[0072] 1. Pre-drilling holes at the corners on both sides of the blade hole boss (see tool path schematic diagram Figure 9 ).

[0073] The corner is R6, and a drill with a diameter of 11.5 is used to drill the hole (see tool schematic diagram Figure 10 ), with a single side allowance of 0.25mm and an effective depth control allowance of 0.5mm, to process the corner (see simulation machining schematic diagram Figure 11 ). The corners on both sides of the boss are relatively narrow, and the R angle is relatively small. Generally, a large tool is used for rough machining, and a small tool is used for corner cleaning. This processing method has low processing efficiency, long processing time, and large tool loss. Pre-drilling with a D11.5 drill Figure 10 ) can remove the allowance: 1. It can improve the processing efficiency and greatly improve the metal removal rate; 2. It can reduce the production cost and reduce the large amount of tool loss caused by small tool corner cleaning; 3. It can improve the continuity of machining and avoid quality accidents caused by frequent tool changing.

[0074] 2. Milling processing

[0075] First, use a D25R1 blade milling cutter for rough machining (see tool path schematic diagram Figure 10 ), leaving an allowance of 0.2mm, then use a D12R1 hard alloy milling cutter to remove the allowance (see tool path schematic diagram Figure 11 ), leaving an allowance of 0.1mm, and finally use a D10R5 ball head milling cutter for profile and circular high-precision blade hole boss finishing (see tool path schematic diagram Figure 12 ). The processing parameters are shown in Table 3.

[0076] Table 3

[0077]

[0078]

[0079] One, high-precision blade hole machining Figure 13 ).

[0080] The diameter of the blade hole is D13 (0-+0.012), only 0.012mm tolerance, the deepest hole is 55mm. The processing of such precision hole, if using milling cutter milling, it is difficult to guarantee the roundness and size, due to let the knife, it is easy to produce oval and taper. If using reamer processing, if the pre-drilled hole is inclined, then the hole reamed also has inclination, can not meet the design requirements. The processing method adopts the method of drilling and boring combination, can process the blade hole with high standard.

[0081] 1. Pre-drill with D10 center drill for centering. Drill 7mm deep, drill the center drill bevel, so that the subsequent drill hole does not swing.

[0082] 2. Drill with D8 carbide drill bit, remove the hole excess, drill the hole through.

[0083] 3. Use D12.7 carbide drill bit to enlarge the hole, further remove the excess, leave a single side 0.15mm excess precision boring.

[0084] 4. Use the boring tool suitable for hole diameter D13 to bore the hole, select the boring tool rod with internal cooling, so that when deep hole boring, there will be no accumulation of dross, tool wear, hole wall scratches, size instability and other quality problems. The processing parameters are shown in Table 4.

[0085] Table 4

[0086] Tool parameters RPM Feed mm / min Depth of cut mm Step over % tool diameter D10 centre drill 1000 200 2 D8 drill 1200 200 3 D12.7 drill 1000 200 3 D13 boring tool 1000 150

[0087] The above is only the preferred embodiment of the present application, not any form of the present application, any skilled in the art, without departing from the scope of the present application, according to the technical essence of the present application, any simple modification, equivalent replacement and improvement of the above embodiment, etc., still belongs to the protection scope of the present application technical scheme.

Claims

1. A method for machining complex casings for aero engines, characterized in that, The casing has a structure with multiple sets of blade holes and bosses. This includes machining the circular high-precision blade hole bosses and blade holes on the casing, machining the casing body with its outer shape and the casing body bosses, and then machining the high-precision blade holes on the casing body bosses. The diameter of the blade holes is D8-D18. The machining of the high-precision blade holes on the casing body or the casing body bosses uses tooling and a CNC machine tool. The tooling includes a first tooling base plate, a second tooling base plate, locating pins, and a clamping device. The first tooling base plate is a circular plate and is fixed to the worktable of the CNC machine tool. The second tooling base plate is also a circular plate covering the first tooling base plate. The clamping device... The circular bottom of the casing is fixed to the second tooling base plate. There are three or more positioning pins between the first and second tooling base plates. The center of both the first and second tooling base plates is opened and a central positioning pin is provided. The second tooling base plate can rotate around the central positioning pin. Small holes are evenly opened along the circumference on the outer side of the circular plate of the second tooling base plate. The distribution angle of the small holes on the circumference corresponds to the distribution angle of the cylindrical blade holes of the casing. Several fixing holes with the same diameter as the outer diameter of the circular plate of the second tooling base plate are opened on the first tooling base plate as pin holes. Positioning pins are provided to pass through the pin holes of the first and second tooling base plates for fixing. The outer side of the circular plate of the second tooling base is evenly provided with several rings of small holes along the circumference, and each ring of circumferential holes corresponds to the positioning of a ring of blade holes machined on the casing. A three-axis CNC machine tool is used for drilling and boring. When the casing is precisely fixed, the first fixture base plate is a circular plate and fixed on the CNC machine tool's worktable. A cylindrical pin is inserted into the positioning pin hole on the second fixture base plate and the pin hole on the first fixture base plate simultaneously to ensure that their angular directions are consistent. When the first fixture base plate is placed and fixed on the machine tool's worktable, the angular direction of the drilling angle is already aligned. Pressing the second fixture base plate and the casing allows for drilling and cutting. A drill bit or boring tool is used to cut up and down along the Z-axis. After one hole is machined, the second fixture base plate is rotated directly to the next angle, and a cylindrical pin is inserted to fix the second fixture base plate, allowing for cutting again. This process is repeated. After one round of holes is completed, the worktable is adjusted to align in the axial direction to machine the second round of blade holes, until holes at different angles are machined. The high-precision blade holes on the boss are machined after tooling positioning: 1) Pre-drill holes with a D10 center drill; 2) Drill holes with a D8 carbide drill bit, remove the excess material in the hole, and drill through the hole; 3) Enlarge the hole with a D12.7 carbide drill bit, further remove the excess material, and leave 0.15mm allowance on one side for precision boring; 4) Boring with a boring bar suitable for a hole diameter of D13, and select a boring bar with internal cooling. Machining steps for the boss of the blade hole: 1) Pre-drill holes at multiple evenly spaced points on both sides of the corner of the boss, i.e., the outer perimeter of the boss's outline, using an 11.5mm diameter drill bit, leaving a 0.25mm allowance on each side. The effective depth controls the actual depth of the boss but leaves a 0.5mm allowance; 2) Roughly machine the toolpath with a D25R1 insert milling cutter, leaving a 0.2mm allowance. Then, use a D12R1 carbide end mill to remove the allowance and machine the toolpath, leaving a 0.1mm allowance. Finally, use a D10R5 ball end mill to finish the profile and the circular high-precision shape of the blade hole boss to obtain the casing body; after the boss is completed, machine the blade hole.

2. The method for machining complex casings of aero engines according to claim 1, characterized in that, The device is equipped with a mechanism to drive the second tooling base plate to rotate. Specifically, the second tooling base plate has threads or teeth on its side and a matching lead screw or worm gear that meshes with the threads or teeth. Adjusting the rotation of the lead screw or worm gear will adjust the rotation of the second tooling base plate.

3. The method for machining complex casings of aero engines according to claim 1, characterized in that, The second tooling base plate has a groove on the contact surface with the casing body to match the flange ring of the casing body. The flange ring has a hole, which is fixed to the hole on the second base plate by a positioning pin. Together with the clamping device, the casing body is fixed to the second tooling base plate.

4. The method for machining complex casings of aero engines according to claim 1, characterized in that, First, machine the high-precision blade holes on the casing or boss. That is, after the outer and inner sides of the casing are machined, leave only a 0.2-2mm allowance. After the flange of the casing reaches the required precision, open the blade holes on the casing.

5. The method for machining complex casings of aero engines according to claim 1, characterized in that, The first and second tooling base plates have matching circular convex rails and grooves on their contact surfaces. The first tooling base plate is machined with the same multiple rings of holes as the second tooling base plate.

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