Aircraft engine nozzle shell processing method and multi-station pressing fixture

Abstract

A method for machining an aero-engine nozzle housing and a multi-station clamping fixture are disclosed, belonging to the field of aero-engine nozzle manufacturing technology. The method is as follows: Uneven allowances and irregular structures are removed to form a regular machining plane with dimensional accuracy requirements; a multi-station clamping fixture is used to center and clamp the nozzle housing blank, completing the final machining of the external dimensions, and precision machining of the datum surface and oil passage holes; the housing is removed for further precision machining; tool marks and residual radius corners are polished; and the datum plane is inspected with coloring. This invention ensures the centering and clamping of the part, avoiding machining deviations due to scribing and alignment errors, thus preventing waste of blank costs. It also avoids positioning datum conversion errors caused by multiple clamping operations and plastic deformation during multiple machining processes, reducing product scrap rates. It eliminates the need for repeated alignment and positioning, and is suitable for batch processing on flexible production lines.

Description

Technical Field

[0001] This invention relates to a processing method for an aero-engine nozzle housing and a multi-station clamping fixture, belonging to the field of aero-engine nozzle manufacturing technology. Background Technology

[0002] The nozzle housing of an aero-engine is a key component of the combustion chamber. As the core framework of the fuel nozzle, it is used to fix precision components such as internal filters, metering valves, atomizing nozzles, and swirlers. The housing ensures that there is no displacement or deformation in each part, avoiding atomization failure. At the same time, it connects to the combustion chamber casing and ensures that the surface accuracy does not fail under high temperature, high pressure, and vibration, thus ensuring the stability of fuel supply to the engine.

[0003] Existing processing technologies typically employ a multi-step, step-by-step processing strategy: Rough machining stage: After scribing the blank, a rough datum is formed, and a large amount of machining allowance is removed from the part; Semi-finishing stage: The outer dimensions of the housing are machined to the final size, and the reference surfaces and holes are semi-finished. Precision machining stage: Precision machining is performed on the reference surfaces and holes in the housing.

[0004] The above process route has the following technical defects: 1. Difficulty in rough machining of parts based on datum. Because the part itself is an irregular shape, and the blank is a die forging, the allowance is unevenly distributed and there are some irregular parts, such as ribs, making centering and scribing difficult. It is impossible to confirm whether the scribing is in the center. When roughing the datum, the scribing needs to be aligned before machining. There are also errors when aligning the lines. With the accumulation of errors, the part is often machined off-center when roughing the datum, or the off-center machining is small and not detected in time, but the minimum wall thickness of the local area exceeds the tolerance during the final finishing, resulting in product scrap.

[0005] 2. Difficulty in controlling the dimensions of thin-walled structures The positioning reference conversion error caused by multiple clamping can easily lead to the minimum wall thickness exceeding the tolerance in some areas due to the alignment error, and plastic deformation in thin-walled areas during processing, resulting in a high product scrap rate. Summary of the Invention

[0006] To address the problems existing in the background technology, the present invention provides a machining method for aero-engine nozzle housings and a multi-station clamping fixture, so as to solve the problems of difficulty in roughing the reference machining of parts and difficulty in controlling the dimensions of thin-walled structures in the existing machining processes.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for processing an aero-engine nozzle housing, the method comprising the following steps: S1: Remove uneven allowance and irregular structure from the nozzle housing blank, and process it to form a regular machining plane with the required dimensional accuracy; S2: A multi-station clamping fixture is used to center and clamp the nozzle housing blank, and the final machining of the outer dimensions of the housing, the reference surface and the oil passage hole position are completed in one clamping. S3: Remove the housing from the multi-station clamping fixture and perform precision machining on the outer diameter and end face of the housing; S4: Polish the tool marks and residual R-angles of the blank produced by machining to achieve a smooth transition; S5: Perform a color check on the reference plane of the shell. If the color check result does not meet the requirements, grind the reference plane until it meets the requirements.

[0008] Furthermore, the multi-station clamping fixture S2 includes a base, a detection reference ball, an adjustable V-block assembly, and a positioning block assembly; the adjustable V-block assembly is mounted on the base and is used to center and clamp the nozzle of the housing; the positioning block assembly is mounted on the base and is used to limit the axial position of the housing and clamp and fix the neck of the housing; the detection reference ball is positioned on the base through its own positioning pin structure and is used for reference alignment before processing.

[0009] Furthermore, the adjustable V-block assembly includes a V-block, a limiting screw, an upper guide block, a support, and a guide block; two guide blocks located on the same straight line are installed on the upper surface of the base, each guide block has a groove in its middle and is slidably connected to the lower end of the corresponding V-block through the groove, the two V-blocks are symmetrically arranged, and each V-block has an arc groove at its upper end, the arc groove being used to clamp the nozzle orifice of the nozzle housing; a support is installed in the middle of the upper surface of the base, the upper surface of the support has a semi-circular hole structure, and an upper guide block is provided above the support. The lower surface of the upper guide block is provided with a stepped hole. The middle part of the stepped hole is a semi-circular hole structure two with the same diameter and length as the semi-circular hole structure one. Large circular holes with a larger diameter than the semi-circular hole structure two are provided on both sides of the stepped hole. The semi-circular hole structure one and the semi-circular hole structure two enclose and form a cylindrical space for the insertion of the limiting screw, which is set in accordance with the through holes at the lower ends of the V-shaped blocks on the left and right sides. The limiting screw is a stepped shaft structure. The small diameter section in the middle is inserted into the cylindrical space, the two large diameter sections in the middle are respectively limited in the corresponding large circular holes, and the large diameter sections at both ends are axially limited in the through holes of the corresponding V-shaped blocks.

[0010] Furthermore, the positioning block assembly includes a positioning block body, a support screw, and a pressure plate; the positioning block body has a semi-arc structure with a cavity in the center, and the support screw is inserted into the threaded hole in the middle of the vertical part of the positioning block body and tightened by the second nut. The inner side of the support screw is a plane with a groove, and the shell rib structure is placed in the groove. The plane provides stable support for the shell; a pressure plate with an inner angled tapered surface is installed on the outer side of the horizontal part of the positioning block body and tightened by a locking screw.

[0011] Furthermore, the base has chamfered corners at all four corners and U-shaped grooves on both sides.

[0012] Furthermore, step S2 includes the following steps: S201: Adjust the position of the adjustable V-block assembly according to the blank size, and clamp the nozzle of the housing in a centered position. S202: Adjust the angle of the housing so that the nozzle end face of the housing rests against the support plane of the positioning block assembly; S203: The housing neck is clamped and fixed by the pressure plate of the positioning block assembly; S204: Align the straight edge reference of the fixture with the inspection reference ball before machining to ensure alignment deviation; S205: Remove machining allowance from the housing mounting and positioning area; S206: Rough machining of the oil passage holes in the housing; S207: The outer dimensions of the housing are precision machined, and the transition points of the housing are smoothed and rounded by using a ball end mill through linkage machining. S208: Finish machining of the oil passage holes and reference plane of the housing.

[0013] Furthermore, in the S3 finishing process, the machining path of the CNC program is corrected based on the actual contour data of the part collected by the coordinate measuring machine of the flexible production line.

[0014] Furthermore, in S5, the coloring inspection requires that the coloring area of ​​the reference plane is not less than 90%. If the coloring area is less than 90%, the reference plane is ground until the coloring area is not less than 90%.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention uses a dedicated multi-station clamping fixture to ensure the centering and clamping of parts, avoiding the waste of raw material costs caused by skewing of parts due to scribing and line finding errors.

[0016] 2. This invention completes the precision machining of external dimensions, reference plane and oil passage holes in one positioning and clamping, avoiding positioning reference conversion errors caused by multiple clamping and plastic deformation caused by multiple machining, thus reducing the product scrap rate.

[0017] 3. This invention uses a straight edge reference for the alignment fixture and a detection reference ball. The parts only need to be clamped on the fixture for processing, without the need for repeated alignment and positioning. It can be adapted to batch processing of flexible production lines.

[0018] 4. This invention solves the problem of cumulative error caused by traditional tooling relying on theoretical models by correcting the processing path based on actual contour data using a three-coordinate measuring instrument for flexible production lines. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 yes Figure 1 AA section view; Figure 3 yes Figure 2 BB section view; Figure 4 yes Figure 3 K-direction view; Figure 5 This is a schematic diagram of the guide block structure; Figure 6 yes Figure 5 It is a side view; Figure 7 This is a schematic diagram of the V-shaped block structure; Figure 8 yes Figure 7 Top view; Figure 9 yes Figure 8 Side view; Figure 10 This is a structural diagram of the support; Figure 11 yes Figure 10 Side view; Figure 12 This is a schematic diagram of the upper guide block; Figure 13 yes Figure 12 The main view; Figure 14 yes Figure 13 CC section view; Figure 15 This is a schematic diagram of the limit screw structure; Figure 16 This is a schematic diagram of the pressure plate structure. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] A method for processing an aircraft engine nozzle housing, the method comprising the following steps: S1: Remove uneven and irregular structures such as ribs and spurs from the nozzle housing blank by milling and other methods to form a regular machining plane with the required dimensional accuracy, which facilitates subsequent clamping and processing to meet the clamping requirements of the flexible production line. S2: A multi-station clamping fixture is used to center and clamp the nozzle housing blank, and the final machining of the outer dimensions of the housing, the reference surface and the oil passage hole position are completed in one clamping. S3: Remove the housing from the multi-station clamping fixture and use appropriate tooling and cutting tools to finish the outer diameter and end face of the housing that could not be machined in S2 due to the limitations of the part structure and fixture space. S4: Use grinding tools to polish the tool marks produced by machining and the residual R angles of the blank to achieve a smooth transition and avoid stress concentration areas; S5: Apply the colorant to the reference plane, and then use a standard plate to check the color of the reference plane of the housing. If the color check result does not meet the requirements, grind the reference plane until it meets the requirements.

[0022] Furthermore, the multi-station clamping fixture mentioned in S2 includes a base 1, a detection reference ball 19, an adjustable V-block assembly, and a positioning block assembly; the adjustable V-block assembly is mounted on the base 1 and is used to center and clamp the nozzle of the housing; the positioning block assembly is mounted on the base 1 and is used to limit the axial position of the housing and clamp and fix the neck of the housing; the detection reference ball 19 is precisely positioned on the base 1 through its own positioning pin structure and is used for reference alignment before processing.

[0023] Furthermore, the adjustable V-block assembly includes a V-block 2, a limiting screw 3, an upper guide block 4, a support 7, and a guide block 9; the upper surface of the base 1 has an integrally formed boss in the middle, and two guide blocks 9 located on the same straight line are installed on the upper surface of the base 1. Each guide block 9 has a sliding groove in the middle and is slidably connected to the lower end of the corresponding V-block 2 through the sliding groove. The two V-blocks 2 are symmetrically arranged, and the upper end of each V-block 2 has an arc groove, which is used to clamp the nozzle mouth of the nozzle housing; the sliding groove is a hollow groove, which can ensure precise fit with the matching V-block 2 and reduce the sliding resistance between the V-block 2 and the V-block 2; the upper surface of the boss of the base 1 is secured by the positioning pin structure of the support 7. The support 7 is equipped with a semi-circular hole structure 1 on its upper surface. An upper guide block 4 is provided above the support 7. A stepped hole is provided on the lower surface of the upper guide block 4. The middle part of the stepped hole is a semi-circular hole structure 2 with the same diameter and length as the semi-circular hole structure 1. Large circular holes with a larger diameter than the semi-circular hole structure 2 are provided on both sides of the stepped hole. The semi-circular hole structure 1 and the semi-circular hole structure 2 enclose and form a cylindrical space for the insertion of the limiting screw 3, which is set in accordance with the through holes at the lower ends of the V-shaped blocks 2 on the left and right sides. The limiting screw 3 is a stepped shaft structure. The small diameter section in the middle is inserted into the cylindrical space, and the two large diameter sections in the middle are respectively limited in the corresponding large circular holes. The large diameter sections at both ends are threaded with locking nuts 20, which are axially limited in the through holes of the corresponding V-shaped blocks 2.

[0024] Furthermore, the positioning block assembly includes a positioning block body 12, a support screw 15, and a pressure plate 17. The positioning block body 12 has a semi-arc structure with a cavity in the center, providing space for the two V-shaped blocks 2 to clamp the spray holes of the housing. The threaded hole in the middle of the vertical part of the positioning block body 12 is through which the support screw 15 is inserted and tightened by the nut 16. The inner side of the support screw 15 is a plane with a groove, in which the housing rib structure is placed, and the plane provides stable support for the housing. The outer side of the horizontal part of the positioning block body 12 is equipped with a pressure plate 17 with an angled tapered surface on the inner side. The angle matches the size of the housing neck to ensure that the housing can be stably clamped and tightened by the locking screw 18.

[0025] Guide block 9, upper guide block 4 and positioning block body 12 are respectively positioned on the boss by corresponding cylindrical pins and fixed on the boss by corresponding screws.

[0026] Furthermore, the four corners of the base 1 are provided with chamfered structures to accommodate the gripping of the robotic arm in the flexible production line. At the same time, to reduce weight, the base 1 is provided with U-shaped groove structures on both sides, which reduces weight while providing a convenient gripping position for the robotic arm.

[0027] Furthermore, step S2 includes the following steps: S201: Adjust the position of the adjustable V-block assembly according to the blank size, and clamp the nozzle of the housing in a centered position. According to the blank size, the operator pushes the two V-blocks 2 to slide in the corresponding guide block 9. When the shell nozzle is located at the center of the arc groove of the two V-blocks 2, tighten the nuts 20 on both sides of the limit screw 3 so that the two V-blocks 2 clamp the shell nozzle and center and clamp the shell nozzle. S202: Adjust the angle of the housing so that the nozzle end face of the housing rests against the support plane of the positioning block assembly; Adjust the angle of the housing so that the nozzle end face of the housing fits tightly against the plane of the support screw 15, and at the same time place the rib structure of the housing into the groove of the support screw 15 to ensure accurate positioning of the housing. S203: The neck of the housing is clamped and fixed by the pressure plate 17 of the positioning block assembly; Push the pressure plate 17 so that the conical surface of the pressure plate 17 fits against the angle of the housing neck, and then tighten the locking screw 18 to fix the pressure plate 17, thereby clamping the housing neck. S204: Align the straight edge reference of the fixture with the inspection reference ball 19 before machining to ensure alignment deviation; The straight edge reference of the fixture is aligned using testing equipment to ensure that its deviation is within 0.01. At the same time, the testing reference ball 19 is aligned to ensure that its positional accuracy is within 0.01, so as to ensure the accuracy of subsequent processing. S205: Remove machining allowance from the housing mounting and positioning area; First, use an indexable insert milling cutter to quickly remove most of the excess material in the housing mounting and positioning area using cavity milling. Then, use a small bar milling cutter to clean the remaining excess material in this area to ensure that the dimensions of this area meet the requirements. S206: Rough machining of the oil passage holes in the housing; First, use a center drill to machine the drill tip according to the point coordinates in the CNC program. After confirming that the position of the drill tip is not deviated from the theoretical position of the part, use a drill bit to rough machine the oil passage hole of the housing to leave allowance for subsequent finishing. S207: The outer dimensions of the housing are precision machined, and the transition points of the housing are smoothed and rounded by using a ball end mill through linkage machining. Use a small end mill to finish the outer dimensions of the housing to meet the final dimensional requirements. Then, use a ball end mill to smooth and round the various transition points of the housing through a linkage machining process to avoid sharp edges or burrs at the transition points. S208: Finish machining of the oil passage holes and reference plane of the housing.

[0028] The reference plane of the housing is precision machined using a T-slot milling cutter to ensure that its flatness and roughness meet the requirements. Then, the various oil passage holes of the housing are precision machined using a reamer and a boring cutter to ensure that the dimensional accuracy and surface roughness of the oil passage holes meet the requirements.

[0029] Furthermore, in the S3 finishing process, the machining path of the CNC program is corrected based on the actual contour data of the part collected by the coordinate measuring machine of the flexible production line to ensure machining accuracy.

[0030] Furthermore, in S5, the coloring inspection requires that the coloring area of ​​the reference plane is not less than 90%. If the coloring area is less than 90%, the reference plane is ground until the coloring area is not less than 90%.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0032] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for processing an aircraft engine nozzle housing, characterized in that: The method includes the following steps: S1: Remove uneven allowance and irregular structure from the nozzle housing blank, and process it to form a regular machining plane with the required dimensional accuracy; S2: A multi-station clamping fixture is used to center and clamp the nozzle housing blank, and the final machining of the outer dimensions of the housing, the reference surface and the oil passage hole position are completed in one clamping. S3: Remove the housing from the multi-station clamping fixture and perform precision machining on the outer diameter and end face of the housing; S4: Polish the tool marks and residual R-angles of the blank produced by machining to achieve a smooth transition; S5: Perform a color check on the reference plane of the shell. If the color check result does not meet the requirements, grind the reference plane until it meets the requirements.

2. The method for processing an aero-engine nozzle housing according to claim 1, characterized in that: The multi-station clamping fixture S2 includes a base (1), a detection reference ball (19), an adjustable V-block assembly, and a positioning block assembly; the adjustable V-block assembly is installed on the base (1) and is used to center and clamp the nozzle of the housing; the positioning block assembly is installed on the base (1) and is used to limit the axial position of the housing and clamp and fix the neck of the housing; the detection reference ball (19) is positioned on the base (1) by its own positioning pin structure and is used for reference alignment before processing.

3. The method for processing an aero-engine nozzle housing according to claim 2, characterized in that: The adjustable V-block assembly includes a V-block (2), a limiting screw (3), an upper guide block (4), a support (7), and a guide block (9); two guide blocks (9) located on the same straight line are installed on the upper surface of the base (1). Each guide block (9) has a groove in the middle and is slidably connected to the lower end of the corresponding V-block (2) through the groove. The two V-blocks (2) are symmetrically arranged. Each V-block (2) has an arc groove at its upper end. The arc groove is used to clamp the nozzle opening of the nozzle housing; a support (7) is installed in the middle of the upper surface of the base (1). The upper surface of the support (7) has a semi-circular hole structure. Above the top of the upper guide block (4), the lower surface of the upper guide block (4) is provided with a stepped hole, the middle part of the stepped hole is a semi-circular hole structure two with the same diameter and length as the semi-circular hole structure one, and large circular holes with a larger diameter than the semi-circular hole structure two are provided on both sides of the stepped hole. The semi-circular hole structure one and the semi-circular hole structure two are closed to form a cylindrical space for the limit screw (3) to be inserted, corresponding to the through holes at the lower ends of the V-shaped blocks (2) on the left and right sides. The limit screw (3) is a stepped shaft structure, the middle small diameter section is inserted into the cylindrical space, the two middle large diameter sections are respectively limited in the corresponding large circular holes, and the two large diameter sections at both ends are axially limited in the through holes of the corresponding V-shaped blocks (2).

4. The method for processing an aero-engine nozzle housing according to claim 3, characterized in that: The positioning block assembly includes a positioning block body (12), a support screw (15), and a pressure plate (17). The positioning block body (12) has a semi-arc structure with a cavity in the center. The support screw (15) is inserted into the threaded hole in the middle of the vertical part of the positioning block body (12) and tightened by the second nut (16). The support screw (15) has a grooved plane on the inner side, and the shell rib structure is placed in the groove. The plane provides stable support for the shell. The outer side of the horizontal part of the positioning block body (12) is equipped with a pressure plate (17) with an angled conical surface on the inner side and is tightened by a locking screw (18).

5. A method for processing an aero-engine nozzle housing according to claim 2, characterized in that: The base (1) has chamfered structures at all four corners and U-shaped groove structures on both sides.

6. A method for processing an aero-engine nozzle housing according to claim 2 or 5, characterized in that: S2 includes the following steps: S201: Adjust the position of the adjustable V-block assembly according to the blank size, and clamp the nozzle of the housing in a centered position. S202: Adjust the angle of the housing so that the nozzle end face of the housing rests against the support plane of the positioning block assembly; S203: The neck of the housing is clamped and fixed by the pressure plate (17) of the positioning block assembly; S204: Align the straight edge reference of the fixture with the detection reference ball (19) before machining to ensure alignment deviation; S205: Remove machining allowance from the housing mounting and positioning area; S206: Rough machining of the oil passage holes in the housing; S207: The outer dimensions of the housing are precision machined, and the transition points of the housing are smoothed and rounded by using a ball end mill through linkage machining. S208: Finish machining of the oil passage holes and reference plane of the housing.

7. A method for processing an aero-engine nozzle housing according to claim 6, characterized in that: In the S3 process, the machining path of the CNC program is corrected based on the actual contour data of the part collected by the coordinate measuring machine of the flexible production line during the finishing process.

8. A method for processing an aero-engine nozzle housing according to claim 7, characterized in that: In S5, the coloring inspection requires that the coloring area of ​​the reference plane is not less than 90%. If the coloring area is less than 90%, the reference plane is ground until the coloring area is not less than 90%.

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