Method for correcting the coaxiality of inner and outer rings of flame tube

Abstract

The present invention discloses a method for correcting the coaxiality of the inner and outer rings of a flame tube. The flame tube is clamped by a fixture, and the flame tube is positioned with a coaxial reference plane. The correction position of the inner ring and the runout difference of the correction position are determined; the fixture drives the flame tube to move along its own axial direction, and at the same time, a roller static pressure correction is applied to the correction position. The correction step is repeated at least twice, and each correction is based on the previous runout difference to determine the axial movement distance until the coaxiality of the inner and outer rings is qualified. This correction method overcomes the drawbacks of limited space for traditional correction. The flame tube is precisely positioned and stably clamped by a fixture, and a roller is used to apply static pressure correction to the position of the flame tube that needs to be corrected. High-precision correction of the coaxiality of the inner and outer rings can be achieved, and defects such as scratches and bruises on the correction surface can be avoided, thereby ensuring the quality of the correction surface. The fixture can also be used as a turning fixture after the flame tube is welded. The fixture only needs to be clamped once, and the coaxial correction of the flame tube is cleverly assisted by a lathe, which can save manufacturing costs.

Description

Technical Field

[0001] The present invention relates to the technical field of aero-engines, and in particular to a method for correcting the coaxiality of inner and outer rings of a flame tube. Background Art

[0002] The flame tube of an aircraft engine is a core component of the aircraft engine. It is difficult to process, has a long cycle, and is extremely valuable. It is generally composed of an inner ring, an outer ring, and a head that are welded together. During the welding process, due to the influence of welding deformation, the coaxiality deviation of the inner and outer rings of the assembled flame tube is relatively large.

[0003] In order to ensure that the machining after welding meets the requirements and the assembly requirements, the final coaxiality of the inner and outer rings is generally controlled within the range of Φ0.3-Φ0.5mm. However, the current situation is that the maximum coaxiality of the flame tube after welding reaches more than Φ1.7mm, which seriously affects the subsequent processing and assembly of the flame tube. Figure 3 and attached Figure 4 The outer ring step dimension L is technically required to be no greater than 0.5. However, when conventional machining of the flame tube causes the coaxiality to be too large, this step cannot be machined, and sometimes a reverse step may occur. Therefore, to ensure that the flame tube meets machining and use requirements, it is usually necessary for a fitter to perform corrections after welding. The correction method is generally to use hammering or a press.

[0004] The knocking correction method is difficult to control the force accurately. At the same time, the concentrated force can easily cause local surface deformation or cracks. In addition, due to the structure of the flame tube, the fitter has no effective space to exert force when knocking, and the correction effect cannot be achieved perfectly.

[0005] Press calibration is suitable for the correction of planes and dimensions such as height or roundness. However, this type of traditional coaxial calibration tooling is complex, costly, and difficult to control springback. The calibration is not flexible enough and is generally rarely used in the aviation field.

[0006] Due to the aforementioned processing difficulties, the coaxial control of the inner and outer rings of the flame tube is currently generally achieved through welding fixtures. Patent publication number CN215200086U discloses a welding fixture for a gas turbine flame tube. The assembly device comprises: a base in the shape of an inverted T, with a transverse section at the bottom and a vertical section at the top, the transverse section fixedly connected to the machine tool; a vertically arranged cylindrical mandrel, coaxially arranged with the vertical section of the base and fixedly connected to the base at its lower end; a mandrel with a diameter that gradually increases from top to bottom and axially provided with multiple bosses along its circumference, which are used to ensure the coaxiality of the various components during assembly; and multiple circular positioning plates with positioning holes in their centers, each for receiving the mandrel. The positioning holes cooperate with the mandrel bosses to measure and correct the fit of the corresponding components. The utility model's description shows that it can effectively ensure the consistency of the overlapping interface dimensions, achieving the ideal welding gap between the cylinder and rings after assembly. It also avoids the need for mouth size adjustment, saving processing time and improving production efficiency.

[0007] However, although the technical solution of the above patent mentions that the coaxiality of each section can be guaranteed after the overall assembly is completed, the flame tube recorded therein is assembled and welded into a cylindrical shape section by section, which is not applicable to a U-shaped flame tube composed of an inner ring, an outer ring and a head. Moreover, the welding tooling in the above patent can only control the coaxiality before welding, but for thin-walled cylindrical parts, coaxial control before welding cannot avoid deformation after welding. In other words, after the parts are welded and the tooling is removed, the parts will inevitably deform again. For example, the flame tube of the above patent still needs to be corrected for deformation after welding by local tapping, inspection, and tapping again... until the correction is qualified, or by mold bulging correction. Moreover, the welding tooling of the above patent is complex in structure, expensive, and cumbersome to operate.

[0008] Therefore, in order to solve the problem that the coaxiality often exceeds the tolerance after welding due to the uncontrollable welding of flame tube and defect repair welding, which causes the flame tube to be scrapped and brings huge losses, a new coaxiality correction method needs to be found to replace the traditional correction operation. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a method for correcting the coaxiality of the inner and outer rings of a flame tube after welding in response to the defects of the prior art. The correction method is simple to operate and truly realizes the controllable coaxial accuracy of the flame tube.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A method for correcting the coaxiality of the inner and outer rings of a flame tube comprises the following steps: clamping the flame tube with a fixture, positioning the flame tube with a coaxial reference plane, determining the correction position of the inner ring and the runout difference of the correction position; causing the fixture to drive the flame tube to move along its own axial direction, and applying roller static pressure correction to the correction position at the same time; repeating the correction operation at least twice, and determining the axial movement distance based on the previous runout difference each time, until the coaxiality of the inner and outer rings is qualified.

[0012] Furthermore, the correction position is determined by finding the point where the difference between the runout of two symmetrical points on the inner ring is the largest.

[0013] Furthermore, the runout difference between two symmetrical points of the inner ring is obtained by rotating the flame tube with a fixture and using a dial indicator.

[0014] Furthermore, the axial movement distance during each correction is determined as follows: The correction position runout difference after the nth correction is Δt n , then the axial movement distance of the n+1th correction is Δt n / 2+(Δt n-1 -Δt n ) / 2.

[0015] Furthermore, the fixture includes a disc, a support block, a pressure plate, a positioning ring and a pressure ring, the support block includes a first surface and a second surface arranged opposite to each other, the support block is arranged on the disc through the first surface, the positioning ring is embedded in the second surface of the support block and partially protrudes from the second surface, the inner hole of the outer ring of the flame tube is sleeved on the outer periphery of the protruding part of the positioning ring, the outer periphery of the positioning ring is the first positioning reference support surface of the flame tube, the second surface of the support block is the second positioning reference support surface of the flame tube, the pressure plate and the support block are connected so that the end face of the inner hole of the flame tube fits with the second support surface, the pressure ring is installed at the head of the flame tube, and the pressure ring and the disc are supported and connected by a support rod.

[0016] Furthermore, the fixture also includes a support plate arranged at the tail of the flame tube, the support plate is sleeved on the outer periphery of the support block, and an auxiliary support is provided on the disc, and the auxiliary support and the support plate abut to assist in positioning the flame tube.

[0017] Furthermore, an auxiliary support is provided through the support rod, and the end face of the auxiliary support abuts against the outer surface of the outer ring of the flame tube.

[0018] Furthermore, the axial movement of the flame tube is achieved by clamping the fixture on the lathe and controlling the movement of the X-axis of the lathe.

[0019] Furthermore, after the fixture is installed on the lathe, the standard for aligning the flame tube positioning reference support surface on the fixture is: the runout of the positioning reference support surface is less than 0.01.

[0020] Furthermore, when the static pressure correction is performed on the inner ring, the fixture drives the flame tube to move slowly along its own axial direction. During the movement, the state of the flame tube needs to be observed in real time.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1) This correction method overcomes the drawback of limited space for traditional shape correction. The flame tube is precisely positioned and stably clamped by a fixture, and a roller is used to apply static pressure correction to the position of the flame tube that needs to be corrected. This can achieve high-precision correction of the coaxiality of the inner and outer rings of the flame tube, while avoiding defects such as scratches and pressure marks on the correction surface, thereby ensuring the quality of the correction surface.

[0023] 2) The fixture of this correction method can also be used as a turning fixture after the flame tube is welded. The fixture only needs to be clamped once. The coaxial correction of the flame tube is cleverly assisted by the lathe, which can save the design and manufacturing cost of a set of fixtures and save the processing cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic structural diagram (cross-sectional view) of the fixture for clamping the flame tube for calibration as described in Example 1;

[0025] Figure 2 This is a schematic diagram of the structure of the contact between the roller and the inner ring of the flame tube in the shape correction position described in Example 1;

[0026] Figure 3 It is a cross-sectional view of the flame tube of the present invention;

[0027] Figure 4 for Figure 3 Enlarged view of part H in the middle. DETAILED DESCRIPTION

[0028] In order to clearly illustrate the technical features of this solution, the technical solution is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0030] In addition, in the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do 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 a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0031] In this application, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0032] In this application, unless otherwise expressly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0033] Example 1

[0034] This embodiment aims to provide a method for calibrating the coaxiality of the inner and outer rings of the flame tube with high precision, simple operation and low cost, specifically, using a fixture 2 to clamp the inner and outer rings of the flame tube. Figure 3The flame tube 1 shown is positioned with the flame tube coaxial reference plane, and the inner ring's shaping position and the runout difference of the shaping position are determined. Then the fixture 2 drives the flame tube 1 to move along the flame tube's own axial direction. While the flame tube 1 is moving axially, the roller 3 is applied with static pressure to correct its shaping position. The correction operation is repeated at least twice. After each correction, the shaping runout difference needs to be detected, and the axial movement distance of the flame tube 1 is determined based on the previous runout difference for each correction until the coaxiality of the inner ring 11 and the outer ring 12 is qualified.

[0035] The coaxial correction of the flame tube serves the subsequent turning process or assembly use. Therefore, in order to reduce the manufacturing cost of the tooling, this correction method can share the correction tooling and the turning fixture, that is, clamping through a set of fixtures 2, while using the existing turning lathe to assist in the correction. This not only realizes the correction operation, but also allows seamless connection to the turning process directly after the correction, significantly reducing the correction and processing costs. In addition, this correction method uses a roller method for static pressure correction. The lathe is fed by a screw. At the same time, combined with the digital display of the dial indicator, it can achieve high-precision correction control of about 0.02, and can also ensure the quality of the correction surface to avoid defects such as scratches and bruises.

[0036] like Figure 1 As shown, the fixture 2 includes a disc 21, a support block 22, a pressure plate 23, a positioning ring 24 and a pressure ring 25. The support block 22 includes a first surface and a second surface arranged opposite to each other. The first surface of the support block 22 fits the disc 21 and is connected to the disc by screws. The positioning ring 24 is embedded in the second surface of the support block 22 and partially protrudes from the second surface. The inner hole of the flame tube outer ring 12 is sleeved on the outer periphery of the protruding part of the positioning ring 24. The outer periphery 241 of the positioning ring is the first positioning reference support surface of the flame tube, and the second surface 221 of the support block is the second positioning reference support surface of the flame tube (the corrected positioning reference is generally consistent with the positioning reference of the lathe process). The pressure plate 23 and the support block 22 are connected by bolts. The two clamp the positioning ring 24 in the middle, and at the same time make the inner hole end face of the flame tube 1 fit with the second surface 221 of the support block. The pressure ring 25 is installed at the flame tube head 13. The pressure ring 25 and the disc 21 are supported and connected by a support rod 26. The support rod 26 is set to be parallel to the axial direction of the flame tube 1.

[0037] To further ensure the stability of the flame tube clamping and improve its calibration accuracy, such as Figure 1As shown, the fixture 2 also includes a support plate 27 arranged at the tail 14 of the flame tube, and the support plate 27 is sleeved on the outer periphery of the support block 22. The support plate 27 and the disc 21 are arranged in parallel. A threaded hole is opened on the disc 21, and an auxiliary support 281 with a threaded section is screwed into the threaded hole. The other end of the auxiliary support 281 abuts against the support plate 27 to limit the support plate 27 to assist in positioning the flame tube. Specifically, the auxiliary support 281 just supports the support plate 27; a thin nut 282 is also sleeved on the auxiliary support 281, and the positioning height of the support plate 27 can be guaranteed to the maximum extent by screwing the thin nut 282 and the threaded section of the auxiliary support 281 together.

[0038] In addition, the fixture is also designed for the circumferential positioning of the flame tube. An auxiliary support 29 is vertically provided on the support rod 26, and the end face of the auxiliary support 29 abuts against the outer surface of the flame tube outer ring 12 to just support the flame tube outer ring.

[0039] The above auxiliary supports are evenly arranged in six on the disc, and the support rods are also evenly arranged in six on the disc. Therefore, six auxiliary supports are distributed circumferentially on the outer ring of the flame tube for abutment. The above structural arrangement increases the overall rigidity of the clamp.

[0040] The following is a step-by-step description of the calibration method:

[0041] S1. Clamping and alignment:

[0042] S11. The fixture 2 is mounted on the lathe faceplate, the second positioning reference surface of the fixture is aligned, and the dial indicator is used to check that the reference surface does not fluctuate by more than 0.01.

[0043] S12. Align the first positioning reference surface of the fixture and check with a dial indicator that the four symmetrical points on the positioning ring 24 do not run out by more than 0.01;

[0044] S13. Tighten the fixture 2, clamp the flame tube 1 to the fixture 2, tighten the screws between the pressure plate 23 and the support block 22, so that the flame tube 1 is compressed;

[0045] S14. Adjust the six auxiliary supports 281 and the thin nut 282 so that the auxiliary supports 281 are just against the support plate 27;

[0046] S15. Adjust the six auxiliary supports 29 so that they just support the outer ring 12 of the flame tube;

[0047] S16. Use a dial indicator to manually rotate the lathe spindle, so that the spindle drives the fixture and then drives the flame tube to rotate slowly, and find the part of the inner ring that needs to be corrected (such as Figure 3 middle ) and find the point with the largest difference between the two symmetrical points, mark the high point position, and record the difference Δt1.

[0048] S2. Coaxiality correction:

[0049] S21. Install the roller 3 on the lathe turret and secure it;

[0050] S22. Adjust the lathe axes and move roller 3 to Figure 2 Turn the lathe spindle to the part to be corrected, fine-tune the high point marked in S16 to align it with the center of the roller, and lock the lathe spindle;

[0051] S23. Slowly move the lathe X-axis, causing the fixture 2 to drive the flame tube 1 to slowly move along its own axis, performing the first static pressure correction on the inner ring 11 by moving a distance Δt1 / 2 to complete the first correction. During the movement, observe the flame tube status in real time and, if necessary, retract the tool before advancing.

[0052] S24. Exit roller 3 and use a dial indicator to align the runout at the inner ring Φ. Determine the runout difference Δt2 between the two symmetrical points at the mark. The springback at this point is approximately (Δt1 - Δt2) / 2.

[0053] S25. Perform a second calibration on the inner ring 11 and slowly move the lathe X axis. The moving distance is the springback amount plus Δt2 / 2, that is: Complete the second calibration;

[0054] S26. Exit roller 3 and check the coaxiality of flame tube 1. If it is unqualified, repeat step S23. The axial movement distance during each correction follows: the difference in the correction position after the nth correction is Δt n , then the axial movement distance of the n+1th correction is Δt n / 2+(Δt n-1 -Δt n ) / 2.

[0055] Generally, two corrections are enough to meet the flame tube coaxiality requirement of Φ0.3-Φ0.5mm, which can meet the flame tube technical requirements.

[0056] This correction method is simple to operate, and the fixture structure is simple. It can stably support the flame tube for precise correction, ensuring excellent post-weld coaxiality of the flame tube to meet the requirements of subsequent processing, assembly, etc.

[0057] Example 2

[0058] The difference between this embodiment and embodiment 1 is that there are three auxiliary supports on the disc.

[0059] Example 3

[0060] The difference between this embodiment and embodiment 1 is that the number of support rods is four and the number of auxiliary supports is four.

[0061] This correction method is not only applicable to the flame tube with inner and outer ring structures of the present invention, but also has the effect of precise correction after welding for flame tubes with other structural forms such as cylindrical structures. It can also be extended to the coaxiality correction of other parts with similar characteristics.

[0062] Obviously, the above embodiments are merely examples for the purpose of clearly illustrating the technical solutions of the present invention, and are not intended to limit the implementation methods of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for correcting the coaxiality of the inner and outer rings of a flame tube, characterized in that: Use a fixture to clamp the flame tube, position it with the coaxial reference plane of the flame tube, determine the correction position of the inner ring and the runout difference of the correction position; make the fixture drive the flame tube to move along its own axial direction, and apply roller static pressure correction to the correction position at the same time. Repeat the correction operation at least twice, and each correction determines the axial movement distance based on the previous runout difference, until the coaxiality of the inner and outer rings is qualified.

2. The method for correcting the coaxiality of the inner and outer rings of the flame tube according to claim 1, characterized in that: The correction position is determined by finding the point where the difference between the runout of two symmetrical points on the inner ring is the largest.

3. The method for correcting the coaxiality of the inner and outer rings of the flame tube according to claim 2, characterized in that: The difference in runout between two symmetrical points on the inner ring is obtained by rotating the flame tube with a fixture and using a dial indicator.

4. The method for correcting the coaxiality of the inner and outer rings of the flame tube according to claim 1, characterized in that: The axial movement distance during each correction is determined as follows: The correction position runout difference after the nth correction is Δt n , then the axial movement distance of the n+1th correction is Δt n / 2+(Δt n-1 -Δt n ) / 2.

5. The method for correcting the coaxiality of the inner and outer rings of the flame tube according to claim 1, characterized in that: The clamp includes a disc, a support block, a pressure plate, a positioning ring and a pressure ring. The support block includes a first surface and a second surface arranged opposite to each other. The support block is arranged on the disc through the first surface. The positioning ring is embedded in the second surface of the support block and partially protrudes from the second surface. The inner hole of the outer ring of the flame tube is sleeved on the outer periphery of the protruding part of the positioning ring. The outer periphery of the positioning ring is the first positioning reference support surface of the flame tube. The second surface of the support block is the second positioning reference support surface of the flame tube. The pressure plate and the support block are connected so that the end face of the inner hole of the flame tube fits with the second support surface. The pressure ring is installed at the head of the flame tube. The pressure ring and the disc are supported and connected by a support rod.

6. The method for correcting the coaxiality of the inner and outer rings of the flame tube according to claim 5, characterized in that: The fixture also includes a support plate arranged at the tail of the flame tube, the support plate is sleeved on the outer periphery of the support block, and an auxiliary support is provided on the disc, and the auxiliary support and the support plate abut against each other to assist in positioning the flame tube.

7. The method for correcting the coaxiality of the inner and outer rings of the flame tube according to claim 5, characterized in that: An auxiliary support is provided through the support rod, and the end face of the auxiliary support abuts against the outer surface of the outer ring of the flame tube.

8. The method for calibrating the coaxiality of the inner and outer rings of the flame tube according to claim 1, characterized in that: The axial movement of the flame tube is achieved by clamping the fixture on the lathe and controlling the movement of the X-axis of the lathe.

9. The method for correcting the coaxiality of the inner and outer rings of the flame tube according to claim 8, characterized in that: After the fixture is installed on the lathe, the standard for aligning the flame tube positioning reference support surface on the fixture is: the runout of the positioning reference support surface is less than 0.

01.

10. The method for calibrating the coaxiality of the inner and outer rings of the flame tube according to claim 1, characterized in that: When performing static pressure correction on the inner ring, the fixture drives the flame tube to move slowly along its own axial direction. During the movement, the status of the flame tube needs to be observed in real time.

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