A precision milling process for aircraft engine casing

Abstract

The present invention belongs to the field of aviation machinery processing technology, and particularly relates to a precision milling process for an aircraft engine casing, comprising a fixed base plate, a T-shaped slide groove, a plurality of T-shaped slide grooves are evenly arranged on the end surface of the fixed base plate in the circumferential direction, a T-shaped slide block is slidably arranged in the T-shaped slide groove, a cushion block is fixedly arranged on the upper end surface of the T-shaped slide block, a second threaded hole is arranged at the center of the fixed base plate, a second threaded rod is spirally arranged in the second threaded hole, a rotating rod is fixedly arranged on the upper end surface of the second threaded rod, a first threaded rod is arranged at the center of the upper end surface of the rotating rod, a detachable upper pressure block and a lower pressure block are slidably arranged above the first threaded rod, and the lower pressure block and the upper pressure block are fixed by meshing to form a pressure block. The present invention can stably clamp the casing without causing deformation, and can also complete ventilation and cooling of the casing as a whole and at the processing point during the processing process.

Description

Technical Field

[0001] The invention belongs to the technical field of aviation equipment processing, and in particular relates to a precision milling process for an aviation engine casing. Background Art

[0002] The fan case of an aircraft engine adopts an internal containment structure. The containment case is a resin-based aramid fiber composite material. Since the size reference of the containment case is on the end face of the fan case, the containment case is fixed to the titanium alloy case by bonding, and the dimensional accuracy is required to be high. The wall thickness of the fan case is relatively thin, so when processing it, the design of the fixture must take into account the application of multiple processes, reduce the number of clamping times, thereby shortening the clamping time and improving the processing accuracy. For areas that are prone to deformation, the auxiliary function of the fixture must be considered to ensure that the processing deformation can be reduced.

[0003] Due to the special nature of the resin-based aramid fiber composite material, it is impossible to use coolant to cool the processing point surface during the processing, and the temperature can only be reduced by air cooling. Therefore, when processing the casing, it is often necessary to install a ventilator at the front end of the tool. However, no matter how small the ventilator is, it will still interfere with the processing, making it impossible to improve the processing accuracy. In any case, the casing processing needs to be clamped and fixed by the tooling. If a gas flow operation can be formed between the tooling and the outside of the casing, it will not interfere with the processing and can effectively ensure that the overall temperature of the casing will not change. Therefore, it is of great significance to design a tooling and process that can stably clamp the casing without causing deformation, and can also complete ventilation and cooling of the entire casing and the processing points during processing. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems in the prior art and propose a precision milling process for aircraft engine casings. The present invention can stably clamp the casing without causing deformation, and can also complete ventilation and cooling of the entire casing and the processing points during the processing.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a precision milling process for an aircraft engine casing, comprising a fixed base plate, a T-shaped slide groove, a plurality of T-shaped slide grooves are evenly arranged on the end surface of the fixed base plate in the circumferential direction, a T-shaped slide block is slidably arranged in the T-shaped slide groove, a cushion block is fixedly arranged on the upper end surface of the T-shaped slide block, a second threaded hole is arranged at the center of the fixed base plate, a second threaded rod is spirally arranged in the second threaded hole, a rotating rod is fixedly arranged on the upper end surface of the second threaded rod, and a plurality of T-shaped slide grooves are evenly arranged on the outer circumferential direction of the rotating rod. There are multiple rotation planes, a first threaded rod is arranged at the center of the upper end surface of the rotating rod, a detachable upper pressing block and a lower pressing block are slidably arranged above the first threaded rod, multiple outwardly protruding pressing plates are evenly arranged on the outer circular surfaces of the upper pressing block and the lower pressing block in the circumferential direction, a second through hole is arranged at the center of the upper pressing block and the lower pressing block, the lower pressing block and the upper pressing block are fixed to form a pressing block through meshing, a sealing ring is arranged on the outer circular surface of the meshing part of the lower pressing block and the upper pressing block, and a fixing nut is spirally arranged on the outer circular surface of the first threaded rod above the upper pressing block. The pressing plate can effectively expand the pressing contact surface, thereby ensuring the stability of the clamping.

[0006] Preferably, a plurality of first threaded holes for fixing are evenly arranged along the circumferential direction between each T-shaped slide groove on the end surface of the fixed base plate, and a plurality of first through holes are evenly arranged along the circumferential direction on the end surface of the fixed base plate between the first threaded holes. The arrangement of the first threaded holes and the first through holes enables the fixed base plate to be freely mounted on the processing table in a variety of ways for processing.

[0007] Preferably, the cushion block is provided with a third through hole, one of which is provided with a detachable positioning pin, and the other is provided with a detachable positioning column, and one side of the third through hole is provided with a third threaded hole on the cushion block side wall, and the third threaded hole is provided with a straight top screw in a spiral fit, and the straight top screw can be abutted against the outer circumferential surface of the positioning column and the positioning pin to form a fixation. The provision of the third threaded hole and the straight top screw can adjust the height of the positioning column or the positioning pin exposed, thereby facilitating the positioning and placement of the receiver.

[0008] Preferably, the upper surface of the fixed bottom plate is evenly provided with a plurality of slag discharge chutes inclined outwards along the circumferential direction between each T-shaped chute, the slag discharge chutes are connected with a slag discharge port on the outer circumferential surface of the fixed bottom plate in the inclined direction, a fixed ring block is fixedly provided in the slag discharge chutes above the slag discharge port and inclined toward the rotating rod, an air jet arc seat is fixedly provided on the inclined end surface of the fixed ring block, an air jet horn is connected on the outer end surface of the air jet arc seat, and a plurality of second air inlet valve pipes are connected at the bottom of the air jet arc seat. The gas ejected from the air jet arc seat can form an air wall outside the casing, so that while increasing the gas circulation to dissipate the processing temperature in time, the dust and dirt produced by processing can also be cleaned out in time.

[0009] Preferably, a ventilation cavity is provided in each pressing plate outside the lower pressing block, a first air intake valve pipe is provided above the ventilation cavity and connected in the upper pressing block, a refrigerator is provided below the first air intake valve pipe and on both sides of the ventilation cavity, a controller is connected between the two refrigerators, a plurality of temperature detectors are provided in the ventilation cavity on one side of the controller, and a plurality of first jet valve ports are provided on the outer circumferential surface of the pressing plate on one side of the ventilation cavity. When the refrigerator starts to cool, the lower pressing block will also be in a relatively cold state, so that the ventilation cavity can not only cool the external processing surface of the casing, but also dissipate heat from the pressing surface.

[0010] Preferably, an annular ventilation ring is provided in the lower pressing block, and the outer side of the ventilation ring is connected to each ventilation cavity through a connecting cavity tube, and an annular jet concave ring is provided at the bottom of the lower pressing block below the ventilation ring, and a plurality of second jet valve ports are evenly arranged in the jet concave ring along the circumferential direction, and each of the second jet valve ports is connected to the ventilation ring. Due to the setting of the connecting cavity tube, the temperature of the gas injected into the ventilation ring is slightly higher than that of the ventilation cavity.

[0011] Preferably, a trumpet surface extending outwardly inclining is arranged at the bottom of the lower pressing block on the outside of the jet concave ring, and a plurality of flexible pads are arranged at the bottom of each pressing plate on the outside of the trumpet surface. The trumpet surface can allow the gas ejected from the second jet valve port to diffuse outwardly and spray onto the press-fit contact surface of the casing, thereby allowing the gas on the contact surface to circulate quickly.

[0012] 1. The present invention adopts the design of T-shaped slide grooves, pads, rotating rods, pressure plates and other parts, so that the tooling can be applied to various occasions and can also clamp and fix various different casings. The three-claw setting of the pressure plate can make the workpiece evenly stressed, greatly improve the clamping pressure and stability, and effectively ensure the processing accuracy.

[0013] 2. The present invention provides the ventilation cavity and the first jet valve port as well as the ventilation ring and the second jet valve port and other parts. When liquid cooling cannot be used during casing processing, the present invention can spray refrigerant gas on the processing surface to reduce the temperature of the processing surface. At the same time, it can also form gas flow on the clamping surface or inside of the casing, so that the temperature inside and at the processing point is balanced, which can effectively avoid cracking of the casing shell.

[0014] 3. The present invention arranges the slag discharge chute, the air jet arc seat and the slag discharge port, so that air circulation can be formed outside the casing during casing processing, so that the temperature can be balanced and the dust generated by processing can be cleaned out in time, effectively improving the processing accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A perspective view of the present invention;

[0016] Figure 2 A top view of the present invention;

[0017] Figure 3 It is a front view of the present invention;

[0018] Figure 4 for Figure 2 Sectional view at AA in the middle;

[0019] Figure 5 for Figure 3 Sectional view at the middle BB;

[0020] Figure 6 It is a three-dimensional diagram of the lower pressing block parts;

[0021] Figure 7 It is the front view of the lower pressing block part;

[0022] Figure 8 for Figure 7 Sectional view at CC;

[0023] Fig. 9 It is a three-dimensional diagram of the cushion block parts;

[0024] Fig.10 for Figure 4 A partial enlarged view of point D in the middle;

[0025] Fig.11 for Figure 5 A partial enlarged view of point E in the middle;

[0026] In the figure: fixed base plate 10, T-shaped slide groove 11, T-shaped slider 49, cushion block 12, second threaded hole 29, second threaded rod 30, rotating rod 21, rotating plane 22, first threaded rod 23, upper pressing block 24, lower pressing block 25, pressing plate 48, second through hole 31, sealing ring 27, fixing nut 26, first threaded hole 28, first through hole 13, third through hole 32, positioning column 14, positioning pin 15, third threaded hole 44, straight top screw 16, slag discharge chute 17, slag discharge port 47, fixed ring block 18, jet arc seat 19, jet horn 20, second air inlet valve pipe 46, ventilation cavity 40, first air inlet valve pipe 45, refrigerator 39, controller 41, temperature sensor 42, first jet valve port 33, ventilation ring 38, connecting cavity pipe 43, jet concave ring 36, second jet valve port 37, horn surface 35, flexible cushion block 34. DETAILED DESCRIPTION

[0027] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0028] In the description of the present invention, it should be noted that the terms "inside", "below", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0029] Embodiment 1:

[0030] Combined with Figure 1 , Figure 5 and Figure 8 As shown, a precision milling process for an aircraft engine casing comprises a fixed base plate 10, a T-shaped slide groove 11, a plurality of T-shaped slide grooves 11 are evenly arranged on the end surface of the fixed base plate 10 in the circumferential direction, a T-shaped slider 49 is slidably arranged in the T-shaped slide groove 11, a cushion block 12 is fixedly arranged on the upper end surface of the T-shaped slider 49, a second threaded hole 29 is arranged at the center of the fixed base plate 10, a second threaded rod 30 is spirally arranged in the second threaded hole 29, a rotating rod 21 is fixedly arranged on the upper end surface of the second threaded rod 30, a plurality of rotating planes 22 are evenly arranged on the outer circumferential surface of the rotating rod 21, and a plurality of rotating planes 22 are evenly arranged on the outer circumferential direction of the rotating rod 21. A first threaded rod 23 is arranged at the center of the upper end surface of the movable rod 21, and a detachable upper pressure block 24 and a lower pressure block 25 are slidably arranged above the first threaded rod 23. A plurality of pressure plates 48 protruding outward are evenly arranged on the outer circumferential surface of the upper pressure block 24 and the lower pressure block 25 in the circumferential direction. A second through hole 31 is arranged at the center of the upper pressure block 24 and the lower pressure block 25. The lower pressure block 25 and the upper pressure block 24 are fixed by meshing to form a pressure block, and a sealing ring 27 is arranged on the outer circumferential surface of the meshing place of the lower pressure block 25 and the upper pressure block 24. A fixing nut 26 is spirally arranged on the outer circumferential surface of the first threaded rod 23 above the upper pressure block 24.

[0031] Furthermore, combined with Figure 2 As shown, a plurality of first threaded holes 28 for fixing are evenly arranged along the circumferential direction on the end surface of the fixed base plate 10 between each T-shaped slide groove 11 , and a plurality of first through holes 13 are evenly arranged along the circumferential direction on the end surface of the fixed base plate 10 between the first threaded holes 28 .

[0032] Furthermore, combined with Figure 1 and Fig. 9As shown, the cushion block 12 is connected with a third through hole 32, one of the third through holes 32 is detachably provided with a positioning pin 15, and the other third through holes 32 are detachably provided with a positioning column 14, and one side of the third through hole 32 is connected with a third threaded hole 44 on the side wall of the cushion block 12, and a straight-shaped top screw 16 is spirally provided in the third threaded hole 44, and the straight-shaped top screw 16 can abut against the outer circumferential surface of the positioning column 14 and the positioning pin 15 to form a fixation.

[0033] Furthermore, combined with Figure 1 and Fig.10 As shown, a plurality of slag discharge chutes 17 inclined outward are evenly arranged along the circumferential direction between each T-shaped chute 11 on the upper end surface of the fixed base plate 10, and a slag discharge port 47 is connected to the outer circumferential surface of the fixed base plate 10 in the inclined direction of the slag discharge chute 17, and a fixed ring block 18 inclined toward the rotating rod 21 is fixedly arranged in the slag discharge chute 17 above the slag discharge port 47, and an air jet arc seat 19 is fixedly arranged on the inclined end surface of the fixed ring block 18, and an air jet bell mouth 20 is connected to the outer end surface of the air jet arc seat 19, and a plurality of second air intake valve pipes 46 are connected to the bottom of the air jet arc seat 19.

[0034] Before performing milling, the operator can screw the bolt into the first threaded hole 28 or the first through hole 13, then fix the fixed base plate 10 on the processing table, and then screw the second threaded rod 30 at one end of the rotating rod 21 into the second threaded hole 29. During the screwing process, the adjustable wrench can be clamped on the rotating plane 22 for rotation. When the rotating rod 21 is fixed, the operator puts a certain number of locating pins 15 and locating columns 14 into the third through holes 32 on the end faces of each pad 12. When the height of the locating pins 15 and the locating columns 14 is adjusted, the locating pins 15 and the locating columns 14 are fixed by screwing the straight-shaped top screw 16 into the third threaded hole 44 and abutting the end faces of the straight-shaped top screw 16.

[0035] The operator can then slide the pad 12 along the T-shaped slide groove 11 to the corresponding hole position of the receiver, and then align the holes of the receiver with the positioning pins 15 and the positioning columns 14 and insert and fix them. When the receiver is placed, the operator can overlap the upper pressure block 24 and the lower pressure block 25, and then insert them into the first threaded rod 23 through the second through hole 31, so as to press the pressure plate 48 on the upper end surface of the receiver, and then screw the fixing nut 26 into the first threaded rod 23 until the bottom end surface of the fixing nut 26 abuts against the upper end of the upper pressure block 24, thereby completing the fixation of the receiver, and then the receiver can be processed.

[0036] During the machining process, multiple jet arc seats 19 arranged on the outer circumferential surface of the fixed base plate 10 will all be started, and the jet arc seats 19 will be filled with gas through the second intake valve pipe 46, and then the gas will be sprayed on the surface of the casing through the jet bell mouth 20 on the outer end face of the jet arc seat 19. The sprayed gas can, on the one hand, blow off the dust generated in the machining process, and on the other hand, cool the casing being machined. Since multiple jet arc seats 19 are arranged along the circumferential direction, an annular gas flow belt can be formed at various places on the outer end face of the casing, which can ensure that the temperature of the outer end face of the casing will not be too high.

[0037] The cleaned dust and dirt will fall onto the slag discharge chute 17 and then be discharged outward through the slag discharge port 47 at one end of the slag discharge chute 17 .

[0038] Embodiment 2:

[0039] Based on the first embodiment, a further embodiment is made, Figure 8 and Fig.11 As shown, a ventilation cavity 40 is provided in each pressure plate 48 on the outer side of the lower pressure block 25, a first air intake valve pipe 45 is provided above the ventilation cavity 40 and connected in the upper pressure block 24, a refrigerator 39 is provided on both sides of the ventilation cavity 40 below the first air intake valve pipe 45, a controller 41 is connected between the two refrigerators 39, a plurality of temperature detectors 42 are provided on one side of the controller 41 in the ventilation cavity 40, and a plurality of first jet valve ports 33 are provided on one side of the ventilation cavity 40 and connected on the outer circumferential surface of the pressure plate 48.

[0040] When the casing is being processed, the equipment can inject gas into the ventilation cavity 40 through the first air inlet valve pipe 45, and the controller 41 arranged in the ventilation cavity 40 will control the refrigerator 39 to start, and the refrigerator 39 will cool the gas entering the ventilation cavity 40. The thermometer 42 arranged in the ventilation cavity 40 can detect the internal temperature of the detector, and the refrigerated gas can be sprayed outwardly onto the inner wall of the casing through the first jet valve port 33, so that the casing can be cooled. In this relationship, since the ventilation cavity 40 is in a cooling state, the lower pressing block 25 and the pressure plate 48 outside the lower pressing block 25 are in a relatively cold state, and the pressure on the end face of the casing will not cause heat accumulation due to the inability of gas to circulate, thereby ensuring the stability of the casing processing data.

[0041] Embodiment three:

[0042] Based on the first or second embodiment, a further embodiment is made, and the attached Figure 6 and Figure 8As shown, an annular ventilation ring 38 is arranged in the lower pressing block 25, and the outer side of the ventilation ring 38 is connected to each ventilation cavity 40 through a connecting cavity tube 43, and an annular jet concave ring 36 is arranged at the bottom of the lower pressing block 25 below the ventilation ring 38, and a plurality of second jet valve ports 37 are evenly arranged in the circumferential direction in the jet concave ring 36, and each of the second jet valve ports 37 is connected to the ventilation ring 38.

[0043] Furthermore, combined with Figure 6 As shown, a trumpet surface 35 extending outwardly and tilted is arranged at the bottom of the lower pressing block 25 on the outside of the jet concave ring 36 , and a plurality of flexible pads 34 are arranged at the bottom of each pressing plate 48 on the outside of the trumpet surface 35 .

[0044] Due to the provision of the flexible pad 34, when the lower pressure block 25 and the upper pressure block 24 are pressed on the surface of the receiver, the phenomenon of contact surface crushing can be avoided. At the same time, since the flexible pad 34 is flexible but has a certain height, the bottom end face of the lower pressure block 25 will not be completely attached to the surface of the receiver, so there is a certain gap for gas circulation, which can facilitate its cooling treatment.

[0045] When the ventilation cavity 40 begins to intake air for cooling, a portion of the gas will enter the ventilation ring 38 through the connecting cavity tube 43, and then be ejected outward through the second jet valve port 37 at the bottom of the ventilation ring 38. Due to the setting of the horn surface 35, the ejected gas will diffuse outward and then be sprayed on the top surface of the casing. In this relationship, since the refrigerator 39 is arranged in the ventilation cavity 40, the temperature of the gas injected into the ventilation ring 38 through the ventilation cavity 40 is much higher than that ejected from the first jet valve port 33. This setting is mainly to facilitate gas circulation, but it will not make the temperature of the top or inside of the casing not much lower than the external processing surface, which can avoid the occurrence of uneven hot and cold inside and outside, thereby reducing the occurrence of casing cracking.

[0046] The above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention; although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention; in addition, the direct or indirect application of the technical solutions of the present invention in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A precision milling tool for an aircraft engine casing, comprising a fixed base plate (10) and a T-shaped slide groove (11), characterized in that: A plurality of T-shaped grooves (11) are evenly arranged on the end surface of the fixed base plate (10) along the circumferential direction, a T-shaped slider (49) is slidably arranged in the T-shaped groove (11), a cushion block (12) is fixedly arranged on the upper end surface of the T-shaped slider (49), a second threaded hole (29) is arranged at the center of the fixed base plate (10), a second threaded rod (30) is spirally arranged in the second threaded hole (29), a rotating rod (21) is fixedly arranged on the upper end surface of the second threaded rod (30), a plurality of rotating planes (22) are evenly arranged on the outer circumferential direction of the rotating rod (21), a first threaded rod (23) is arranged at the center of the upper end surface of the rotating rod (21) ), a detachable upper pressing block (24) and a lower pressing block (25) are slidably arranged above the first threaded rod (23), a plurality of outwardly protruding pressing plates (48) are evenly arranged on the outer circumferential surface of the upper pressing block (24) and the lower pressing block (25) along the circumferential direction, a second through hole (31) is arranged at the center of the upper pressing block (24) and the lower pressing block (25), the lower pressing block (25) and the upper pressing block (24) are fixed by meshing to form a pressing block, a sealing ring (27) is arranged on the outer circumferential surface of the meshing point between the lower pressing block (25) and the upper pressing block (24), and a fixing nut (26) is spirally arranged on the outer circumferential surface of the first threaded rod (23) above the upper pressing block (24).

2. The precision milling tool for aircraft engine casing according to claim 1, characterized in that: A plurality of first threaded holes (28) for fixing are evenly arranged along the circumferential direction on the end surface of the fixed base plate (10) between each T-shaped slide groove (11), and a plurality of first through holes (13) are evenly arranged along the circumferential direction on the end surface of the fixed base plate (10) between the first threaded holes (28).

3. The precision milling tool for aircraft engine casing according to claim 2, characterized in that: The cushion block (12) is provided with a third through hole (32) in communication, a positioning pin (15) is detachably provided in one of the third through holes (32), and a positioning column (14) is detachably provided in the other third through holes (32). A third threaded hole (44) is provided in communication on one side of the third through hole (32) on the side wall of the cushion block (12), and a straight-shaped top screw (16) is provided in the third threaded hole (44) in a spiral manner. The straight-shaped top screw (16) can abut against the outer circumferential surface of the positioning pin (15) and the positioning column (14) to form a fixation.

4. The precision milling tool for aircraft engine casing according to claim 3, characterized in that: A plurality of slag discharge chute grooves (17) inclined outward are evenly arranged on the upper end surface of the fixed bottom plate (10) between each T-shaped slide groove (11) along the circumferential direction; a slag discharge port (47) is arranged in communication with the outer circumferential surface of the fixed bottom plate (10) in the inclination direction of the slag discharge chute (17); a fixed ring block (18) is fixedly arranged above the slag discharge port (47) in the slag discharge chute (17) and is inclined toward the rotating rod (21); an air jet arc seat (19) is fixedly arranged on the inclined end surface of the fixed ring block (18); an air jet bell mouth (20) is arranged in communication with the outer end surface of the air jet arc seat (19); and a plurality of second air intake valve pipes (46) are arranged in communication with the bottom of the air jet arc seat (19).

5. The precision milling tool for aircraft engine casing according to claim 4, characterized in that: A ventilation cavity (40) is provided in each pressing plate (48) outside the lower pressing block (25); a first air intake valve pipe (45) is provided above the ventilation cavity (40) and is connected to the upper pressing block (24); refrigerators (39) are provided on both sides of the ventilation cavity (40) below the first air intake valve pipe (45); a controller (41) is connected between the two refrigerators (39); a plurality of temperature measuring devices (42) are provided on one side of the controller (41) in the ventilation cavity (40); and a plurality of first jet valve ports (33) are provided on the outer circumferential surface of the pressing plate (48) and are connected to the ventilation cavity (40).

6. The precision milling tool for aircraft engine casing according to claim 5, characterized in that: An annular ventilation ring (38) is arranged inside the lower pressing block (25), and the outer side of the ventilation ring (38) is connected to each ventilation cavity (40) through a connecting cavity tube (43). An annular jet concave ring (36) is arranged below the ventilation ring (38) at the bottom of the lower pressing block (25), and a plurality of second jet valve ports (37) are evenly arranged in the circumferential direction inside the jet concave ring (36), and each of the second jet valve ports (37) is connected to the ventilation ring (38).

7. The aircraft engine casing precision milling tool according to claim 6, characterized in that: A trumpet surface (35) extending outwardly and tilted is arranged on the outside of the jet concave ring (36) at the bottom of the lower pressing block (25), and a plurality of flexible pads (34) are arranged on the outside of the trumpet surface (35) at the bottom of each pressing plate (48).

8. The process for performing precision milling of an aircraft engine casing using a precision milling tool for an aircraft engine casing according to claim 7, characterized in that: The process is as follows: S1: The processing personnel can fix the fixed base plate on the processing table, and then adjust the distance between the pads to fix the rotating rod and the second threaded rod on the fixed base plate; S2: After aligning each hole of the casing with the positioning pin and the positioning column, the casing is placed and then clamped and fixed by a pressing block; S3: The casing is subjected to milling processing. During the processing, gas is filled into the ventilation cavity provided in the lower pressing block. The gas is cooled by the refrigerator and then sprayed onto the processing surface of the casing through the first jet valve port, thereby performing a local temperature reduction treatment on the processing surface. S4: The gas poured into the ventilation cavity will also enter the ventilation ring, and then be sprayed onto the pressed end surface of the casing through the second jet valve port at the bottom of the ventilation ring, so that the gas on the pressed surface can flow, thereby avoiding the occurrence of local heat accumulation; S5: During the machining process, the jet arc seat will spray gas, thus forming a gas circulation outside the casing and clearing the dust; S6: After the processing is completed, the operator can take away the receiver after removing the lower pressure block and the upper pressure block.

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