Method for processing main shaft of three-segment welded air energy storage axial flow compressor

Abstract

The application relates to the technical field of compressor main shaft processing, and proposes a processing method of a three-section welding type air energy storage axial flow compressor main shaft, which comprises the following steps: positioning end faces and tailstock holes are respectively processed at both ends of workpieces of first and second sections, then the butt joint and the welding bevel of the section are processed; the support part is contacted with the outer circle of the workpiece and adjusted to be coaxial with the tailstock axis in a state of tailstock holding, then the tailstock is removed, the support center of the support part is overlapped with the tailstock axis; the weight-reducing cavity of the section is processed; the internal hole cavity of the middle section is processed by adopting a tool bar provided with a counterweight structure; center holes are respectively processed at both ends of the integral main shaft; the workpiece is supported by adopting a double-tailstock mode, the outer circle processing of the integral main shaft is completed, and the integral outer circle and the internal processed hole cavity have the second coaxiality. The method realizes complete, reliable and engineering feasible processing and manufacturing of the three-section welding type air energy storage axial flow compressor main shaft.

Description

Technical Field

[0001] This application relates to the field of compressor spindle machining technology, and more specifically, to a machining method for a three-section welded air storage axial flow compressor spindle. Background Technology

[0002] The new generation of air-storage axial compressor spindle adopts a three-section welded structure, consisting of a left, middle, and right section welded together after being positioned by axial and radial locating edges with a thickness of 2mm. The total length of the spindle is nearly 9m, the maximum diameter is about 1.5m, and the total weight reaches 45.5t. To reduce the overall weight of the spindle, each section has a weight-reducing cavity. To meet the dynamic balance requirements of the entire spindle, the design specifies that the coaxiality of the integral spindle inner hole, locating locating edges, and weight-reducing cavities relative to the outer circle should not be less than 0.02mm. However, after welding, the weight-reducing cavity and inner hole are no longer connected to the outside, making it impossible to achieve this coaxiality requirement using conventional processes—that is, using the inner hole of the weight-reducing cavity as a reference for single clamping and machining with the outer circle—leading to extreme difficulties in ensuring accuracy.

[0003] For the left and right sections of the spindle, the coaxiality between their outer diameters, the stop, and the weight-reducing cavity is required to be 0.02mm. However, due to the limitations of the weight-reducing cavity structure on the end face connecting to the middle section, the center hole cannot be machined using conventional methods, making it difficult to guarantee coaxiality. Theoretically, the weight-reducing cavity, stop, and outer diameter can be machined in one operation by machining the support position near the stop and using a chuck clamping method in conjunction with the center rest supporting the outer diameter support position, thus meeting the coaxiality requirement. However, the support ball of the existing lathe center rest is a split adjustment structure, which cannot achieve linkage alignment, making alignment extremely difficult in actual operation. Therefore, a more feasible process solution is urgently needed to ensure the coaxiality of the relevant structures of the left and right sections.

[0004] The spindle's middle section has an inner hole length of nearly 5m and a minimum diameter of only 500mm. During machining, a coaxiality of 0.02mm between the inner hole and outer diameter is required. However, conventional cutting tools lack sufficient rigidity and stability for this deep hole operation, making it difficult to meet the precision requirements. Furthermore, the middle section weighs 36.225t and has an irregular shape, lacking suitable lifting locations, posing significant challenges to lifting operations during transport and assembly. The right section of the spindle's weight-reduction cavity has an axial length of nearly 500mm, and the tool holder rigidity is also insufficient during turning. In addition, the sections are fitted with thin-walled stop joints with a thickness of only 2mm. The tolerances for the inner and outer diameters at the stop joints are extremely stringent, requiring precise measurement after machining. However, due to the thin structure, conventional measuring tools are insufficient for effective inspection. Moreover, the stop joint, as a critical structure for docking and positioning, must maintain its dimensional accuracy. The thin-walled structure is highly susceptible to damage during transport; therefore, a specialized stop joint protection plan is needed to ensure quality control throughout the machining and transport process.

[0005] Therefore, there is an urgent need to develop a machining method for a three-section welded air storage axial flow compressor spindle to overcome the limitations of conventional processes and structures, and to provide a complete, reliable and engineering-feasible manufacturing solution for ultra-large segmented welded spindles. Summary of the Invention

[0006] To solve at least one of the above-mentioned technical problems, this application proposes a method for machining the main shaft of a three-section welded air storage axial flow compressor.

[0007] In view of this, this application proposes a machining method for a three-section welded air storage axial flow compressor main shaft. The main shaft includes a first section, a middle section, and a second section. Each section has a weight-reducing cavity inside, and adjacent sections are positioned by a stop fit. The method includes the following steps: For the first and second sections, the end weight-reducing cavities are reserved and not machined. Positioning end faces and center holes are machined at both ends of the workpiece. Then, the workpiece is clamped by a chuck with a center. The stop and welding bevel of this section are machined. While keeping the center in the holding state, the support component is brought into contact with the outer circle of the workpiece and adjusted to be coaxial with the center axis. Then, the center is removed so that the support center of the support component coincides with the center axis. The chuck is used to clamp the support component. The method involves machining the weight-reducing cavity of the section to achieve a first coaxiality between the stop, welding bevel, weight-reducing cavity, and the outer circle of the section; using a tool holder equipped with a counterweight structure to machine the internal cavity of the intermediate section to achieve a first coaxiality between the internal cavity and the outer circle of the section; welding the first section, intermediate section, and second section together after positioning them with the stop; machining center holes at both ends of the integral spindle, ensuring that the axes of the center holes at both ends are collinear with the axes of the machined cavities of each section; using the center holes at both ends of the integral spindle as positioning references, supporting the workpiece with a double-center method to complete the machining of the outer circle of the integral spindle, achieving a second coaxiality between the integral outer circle and the machined internal cavity, which is the target coaxiality requirement for the integral spindle.

[0008] In some feasible methods, machining the positioning end face and center hole for the first and second segments includes the following steps: using a four-jaw chuck to hold and align the small end, setting up a center support to support the large end shaft diameter, and machining the small end support position; using a four-jaw chuck to hold and align the large end, setting up a center support to support the small end support position, flattening the small end end face after alignment, and machining the small end center hole; mounting the small end center, using a four-jaw chuck to hold and align the large end shaft diameter, flattening the large end end face after alignment, and machining the large end center hole.

[0009] In some feasible methods, machining the stop and welding bevel for the first and second segments includes the following steps: clamping the large end center, using a four-jaw chuck to hold the small end position, and machining the outer circle of the large end; machining the bevel, stop and chamfer, leaving a allowance for the stop; precision machining the large end face and chamfer.

[0010] In some feasible methods, machining the weight reduction cavity for the first and second segments includes the following steps: keeping the center in the supporting state, contacting and aligning the center frame with the outer circle of the large end of the spindle, and removing the center after alignment; using a chuck to clamp the small end, supporting the machined outer circle of the large end with the center frame, using a dial indicator to ensure coaxiality ≤0.01mm, and machining the weight reduction cavity according to the drawings.

[0011] In some feasible methods, the deep weight reduction cavity of the second section is machined by a combination of turning and boring. The deep weight reduction cavity is divided into a first layer and a second layer along the axial direction. The combination of turning and boring includes the following steps: clamping and aligning the small end on the lathe, supporting it on the outer circle with a horizontal lathe bracket, using the machined outer circle of the large end as a reference to straighten and align it with a dial indicator, with an alignment accuracy of ≤0.01mm, and turning the first layer of weight reduction cavity close to the large end face; using boring, aligning with the inner hole of the second section flange, straightening it along the spindle axis, with a dial indicator alignment accuracy of ≤0.01mm, and boring the second layer of weight reduction cavity.

[0012] In some feasible methods, the integral spindle includes an inlet side and an outlet side. Machining the center hole on the inlet side of the integral spindle includes the following steps: clamping the inlet side spindle diameter with a four-jaw chuck, supporting the other end with a center, aligning with the outer circle of the welded flange on the middle section of the inlet side, and machining the mounting position at the spindle diameter near the bearing area of ​​the chuck; turning and clamping, clamping the outlet side spindle diameter with a four-jaw chuck, supporting the workpiece at the inlet side mounting position with a center rest, and machining the inlet side end face and drilling the center hole according to the design drawings.

[0013] In some feasible methods, machining a center hole on the exit side of the integral spindle includes the following steps: clamping the exit side spindle diameter with a four-jaw chuck, supporting the other end with a center, aligning with the outer circle of the welded flange on the exit side of the middle section, and machining a support position on the spindle diameter side near the bearing area of ​​the chuck; turning the spindle around and clamping it, clamping the inlet side spindle diameter with a four-jaw chuck, supporting the workpiece at the exit side support position with a center rest, and machining the exit side end face and drilling a center hole according to the design drawings.

[0014] In some feasible methods, the positioning stops of the first and second segments are processed and protected as follows: When processing a single piece, leave a machining allowance of not less than 10mm for the axial length of the positioning stop; after the positioning dimension of the outer circle of the stop is inspected and approved, process the positioning stop to the axial dimension required by the drawing; during transportation, fit a fully enclosed nylon protective clip on the outside of the positioning stop and lock it with screws on the split face of the clip to prevent the positioning stop from being damaged during transportation.

[0015] In some feasible methods, when hoisting a single section in the middle, a hoisting beam is used in conjunction with a wire rope. The hoisting beam is an H-shaped beam with multiple lifting lugs and stiffening plates. The bottom of the hoisting beam is equipped with a support base, and the lifting lugs are equipped with shackles.

[0016] In some feasible methods, machining the internal cavity of the intermediate section specifically includes: providing a tool holder, fixing the tool holder to the lathe tool holder with a set screw via an arc-shaped tool post, determining the counterweight position at one end of the tool holder through finite element analysis and adding the counterweight, and machining the internal cavity of the intermediate section using the tool holder.

[0017] Compared with related technologies, this application has the following technical advantages: The machining method for the three-section welded air-storage axial-flow compressor spindle provided in this application achieves high-precision manufacturing of an ultra-long welded spindle through a combination of staged clamping method conversion, independent segmented machining, and overall unified datum precision machining. The reserved weight-reducing chambers in each section and the step-by-step machining reduce the machining load of a single clamping operation. The support components inherit the datum conversion of the center axis, ensuring the continuity of the clamping datum. Finally, the overall precision machining is completed using the center hole as a unified datum, ensuring the operational reliability and service life of the air-storage axial-flow compressor spindle under high-speed conditions.

[0018] Additional aspects and advantages of this application will become apparent in the following description or may be learned by practice of this application. Attached Figure Description

[0019] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 A schematic flowchart of a machining method for a three-section welded air storage axial flow compressor spindle according to one embodiment of this application is shown. Figure 2 A partial cross-sectional view of the main shaft of a three-section welded air-storage axial compressor according to one embodiment of this application is shown; Figure 3 A cross-sectional view of the welded state of the main shaft of a three-section welded air storage axial flow compressor according to one embodiment of this application is shown. Figure 4 A partial sectional view of the left segment of the main shaft in one embodiment of this application is shown; Figure 5 A schematic diagram of the structure of the middle section of the spindle in one embodiment of this application is shown; Figure 6 A partial sectional view of the right segment of the main shaft in one embodiment of this application is shown; Figure 7 It shows Figure 6 Enlarged view of part A; Figure 8 This illustration shows one of the structural schematic diagrams of a tool holder according to one embodiment of the present application; Figure 9 A second schematic diagram of the tool holder structure in one embodiment of this application is shown; Figure 10 A schematic diagram showing the hoisting state of the intermediate section of the main shaft in one embodiment of this application is illustrated; Figure 11 A schematic diagram of the structure of a lifting beam in one embodiment of this application is shown.

[0020] in, Figures 2 to 11 The correspondence between the reference numerals and component names in the attached drawings is as follows: 100 Left section of main spindle, 110 Middle section of main spindle, 120 Right section of main spindle, 130 Weight reduction cavity, 140 Stop, 142 Welding bevel, 150 Lifting beam, 152 Lifting lug, 154 Rib plate, 156 Support base, 158 Shackle, 160 Tool holder, 162 Counterweight structure, 170 Large end outer circle. Detailed Implementation

[0021] To better understand the above-mentioned objectives, features, and advantages of this application, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of this application is not limited to the specific embodiments disclosed below.

[0023] The following reference Figures 1 to 11 This application describes a method for machining the main shaft of a three-section welded air storage axial flow compressor according to some embodiments.

[0024] like Figure 1 As shown, this application proposes a machining method for a three-section welded air storage axial flow compressor main shaft. The main shaft includes a first section, a middle section, and a second section. Each section has a weight-reducing cavity inside, and adjacent sections are positioned by a stop fit. The method includes the following steps: S202: For the first and second sections, leave the end weight reduction cavity unprocessed, machine the positioning end face and center hole at both ends of the workpiece respectively, then clamp the workpiece with a chuck and center, and machine the stop and welding bevel of the section. S204: Keep the center in the holding position, contact the support component with the outer circle of the workpiece and adjust it to be coaxial with the center axis, then remove the center so that the support center of the support component coincides with the center axis; S206: The weight reduction cavity of this section is machined by using a chuck and supporting components to ensure that the stop, welding bevel, weight reduction cavity and outer circle of this section have the first coaxiality. S208: The internal cavity of the middle section is machined using a tool holder equipped with a counterweight structure, so that the internal cavity and the outer circle of the section have the first coaxiality; S210: The first section, the middle section and the second section are welded together after being positioned by the stop; S212: Machine center holes at both ends of the integral spindle, and make the axis of the center holes at both ends collinear with the axis of each machined cavity; S214: Using the center holes at both ends of the integral spindle as the positioning reference, the workpiece is supported by a double center method to complete the outer circle machining of the integral spindle, so that the integral outer circle and the internal machined cavity have a second coaxiality. The second coaxiality is the target coaxiality requirement of the integral spindle.

[0025] This application provides a machining method for the spindle of a three-section welded air-storage axial-flow compressor. For the first and second sections, a clamping and conversion strategy is proposed, involving establishing the axis with a center, replacing the center with a support component, and machining the support component with a chuck. This solves the problem of difficulty in alignment caused by the inability to adjust the split support balls of the existing lathe center rest in a coordinated manner. The coaxial adjustment of the support component and the outer circle of the workpiece is completed while the center is held in place. After removing the center, the support component inherits the center axis, avoiding cumulative errors caused by datum conversion. The stop, weld bevel, and weight-reducing cavity are machined using this clamping method, all formed under the same rotation center, ensuring the initial coaxiality of the stop, bevel, weight-reducing cavity, and outer circle. Simultaneously, the provision for post-machining of the end weight-reducing cavity avoids interference with the coaxiality guarantee of the end face center hole, ensuring that the coaxial relationship between the internal features of each section and the outer circle is established before welding.

[0026] In the welding and assembly process, a stop joint is used for positioning. The stop joint serves as both a precise positioning reference before welding and a connecting structure after welding, ensuring the initial alignment of the three shaft segments. After welding, center holes are machined at both ends of the integral spindle, ensuring that the axes of these center holes are collinear with the axes of the machined cavities in each segment. This transfers the existing first coaxiality of each segment to the integral spindle through the center holes, establishing a unified reference throughout the entire spindle. Finally, the integral spindle is supported by double centers for outer diameter finishing. Using the center holes as a precision reference, the outer diameter and internal cavities of the integral spindle achieve the second coaxiality, i.e., the target coaxiality requirement. This two-stage guarantee mechanism of first and second coaxiality ensures that the final accuracy is not significantly affected by welding deformation and cumulative errors in each segment.

[0027] This machining method achieves high-precision manufacturing of ultra-long welded spindles by combining phased conversion of clamping methods, independent segmented machining, and overall unified datum precision machining. The pre-reserved weight-reduction chambers in each section and the step-by-step machining reduce the machining load of a single clamping operation. The support components inherit the datum conversion of the center axis, ensuring the continuity of the clamping datum. Finally, the center hole is used as a unified datum for overall precision machining, ensuring the operational reliability and service life of the air storage axial flow compressor spindle under high-speed conditions.

[0028] The first segment corresponds to the left segment of the main axis, the second segment corresponds to the right segment of the main axis, and the middle segment corresponds to the middle segment of the main axis.

[0029] In some embodiments provided in this application, machining the positioning end face and the center hole for the first and second segments includes the following steps: using a four-jaw chuck to hold and align the small end, setting up a center frame to support the large end shaft diameter, and machining the small end frame position; using a four-jaw chuck to hold and align the large end, setting up a center frame to support the small end frame position, flattening the small end end face after alignment, and machining the small end center hole; mounting the small end center, using a four-jaw chuck to hold and align the large end shaft diameter, flattening the large end end face after alignment, and machining the large end center hole.

[0030] In this embodiment, high-precision machining of the two end faces and center holes of the compressor spindle is achieved through the alternating engagement of a four-jaw chuck and a center rest. The four-jaw chuck clamps the small and large ends separately and aligns them one by one. Combined with the rigid support of the center rest for the non-machined sections, bending deformation and vibration of the workpiece during cutting are effectively suppressed, ensuring the flatness of the end faces and the positional accuracy of the center holes. Simultaneously, using the machined surfaces as the positioning reference for subsequent clamping reliably ensures the coaxiality of the center holes at both ends with the outer cylindrical axis, avoiding the problem of insufficient precision at both ends in a single clamping operation.

[0031] In terms of process arrangement, the scheme adopts a progressive processing strategy of processing the small end first and then the large end. First, the small end face and center hole are processed based on the small end position. Then, the large end is processed by reverse clamping based on the small end center hole. This realizes the unified transfer of the reference and reduces the cumulative error.

[0032] In some embodiments provided in this application, the machining of the stop and welding bevel for the first and second segments includes the following steps: clamping the large end center, using a four-jaw chuck to clamp the small end position, and machining the outer circle of the large end; machining the bevel, stop and chamfer, with a allowance reserved for the stop; precision machining the large end face and chamfer.

[0033] In this embodiment, a combined clamping mechanism using a large-end center and a small-end four-jaw chuck is employed. The pre-machined small-end support position and center hole serve as a unified reference, ensuring the stability and coaxiality accuracy of the workpiece axis during turning. The dual-point support of the center and chuck ensures the roundness and cylindricity of the outer circle. Beveling, stopping, and chamfering are completed simultaneously in the same clamping state, avoiding reference conversion errors caused by multiple clamping operations, and reliably guaranteeing the relative positional accuracy of the beveling angle, stopping dimension, and outer circle.

[0034] In terms of process arrangement, a roughing and finishing separation strategy is adopted. Machining allowances are reserved for the stops, bevels, and chamfers. Roughing is performed first, followed by finishing, effectively controlling the impact of cutting forces on the machined surfaces and ensuring the dimensional accuracy and surface quality of the stops. Finishing the end face and chamfering serves as the final process, further improving the flatness of the end face and the consistency of the chamfers, meeting the assembly requirements of the welded bevel. The entire solution features a unified benchmark and concentrated processes, requiring no special tooling, making it suitable for machining stops and bevels on single-piece or small-batch shaft parts, balancing accuracy and efficiency.

[0035] In some embodiments provided in this application, the machining of the weight reduction cavity for the first and second segments includes the following steps: keeping the center in a supporting state, contacting and aligning the center frame with the outer circle of the large end of the spindle, and removing the center after alignment; using a chuck to clamp the small end, supporting the machined outer circle of the large end with the center frame, using a dial indicator to ensure coaxiality ≤ 0.01mm, and machining the weight reduction cavity according to the drawings.

[0036] In this embodiment, the problem of datum transfer in the machining of the weight reduction cavity is solved by adopting a clamping and conversion strategy of first center alignment and then center rest replacement. With the center held in place, the center rest is aligned with the outer diameter of the large end, ensuring strict alignment between the center rest support axis and the center hole axis. Then, the center is removed, and the center rest becomes the new support datum, ensuring the continuity of the axis during datum conversion and avoiding positioning deviations caused by directly aligning with the outer diameter of the blank. The clamping method of using a chuck to hold the small end and the center rest to support the machined outer diameter of the large end, combined with dial indicator alignment, controls the coaxiality within 0.01mm, providing a high-precision rotation center for the machining of the weight reduction cavity.

[0037] This clamping method ensures that the stop, weld bevel, and weight-reducing cavity are machined under the same datum, rigorously guaranteeing the positional accuracy among them. As an internal deep-hole structure, the uniformity of the weight-reducing cavity's wall thickness directly depends on the accuracy of the rotation center during machining. Controlling the coaxiality to ≤0.01mm ensures consistent cavity wall thickness, avoiding localized insufficient wall thickness or stress concentration issues caused by eccentric machining. After this process, the initial coaxiality of the stop, bevel, weight-reducing cavity, and outer circle is formally established, providing a reliable single-segment accuracy foundation for subsequent three-section welding alignment and overall finishing.

[0038] In some embodiments provided in this application, the deep weight reduction cavity of the second section is machined by a combination of turning and boring. The deep weight reduction cavity is divided into a first layer and a second layer along the axial direction. The combination of turning and boring includes the following steps: clamping and aligning the small end on the lathe, supporting it on the outer circle with a horizontal lathe bracket, using the machined outer circle of the large end as a reference to straighten and align it with a dial indicator, with an alignment accuracy of ≤0.01mm, and turning the first layer of weight reduction cavity close to the large end face; using boring, aligning with the inner hole of the second section flange, straightening it along the spindle axis, with a dial indicator alignment accuracy of ≤0.01mm, and boring the second layer of weight reduction cavity.

[0039] In this embodiment, a combined turning and boring layered machining strategy is adopted for the deep weight reduction cavity of the second section, effectively solving problems such as insufficient tool rigidity, difficult chip removal, and severe tool deflection in one-time machining of deep cavities. The first layer of weight reduction cavity is close to the large end face and is machined by turning. The machined outer circle of the large end is used as a reference for straightening and alignment with a dial indicator, and the alignment accuracy is controlled within 0.01mm. This fully utilizes the advantages of high machining efficiency and controllable cutting force of turning, while ensuring the coaxiality of the first layer cavity with the outer circle by using a high-precision outer circle as a reference. The horizontal lathe support effectively suppresses vibration and deflection during overhang machining, ensuring rotational stability during the turning process.

[0040] The second weight-reducing cavity is located deep within the main body and is machined using a boring method. Alignment is achieved using the inner bore of the second flange section as a reference, and the bore is straightened axially, with alignment accuracy controlled within 0.01mm. The flange inner bore, as a high-precision pre-machined inner bore reference, has better coaxiality than the outer diameter reference, making it more suitable for axial control during deep hole boring. The boring method provides tool rigidity and strong guiding properties, effectively ensuring the straightness and wall thickness uniformity of the deep cavity. The separate machining and alignment of the two layers ensures progressively higher coaxiality throughout the deep weight-reducing cavity, avoiding the accuracy degradation at the end of the deep cavity that occurs with a single machining method. This ensures that the overall weight-reducing cavity meets the dual requirements of spindle lightweighting and high strength.

[0041] In some embodiments provided in this application, the integral spindle includes an inlet side and an outlet side. Machining a center hole on the inlet side of the integral spindle includes the following steps: clamping the inlet side spindle diameter with a four-jaw chuck, supporting the other end with a center point, aligning with the outer circle of the welded flange on the middle section of the inlet side, and machining a support position on the spindle diameter near the bearing area of ​​the chuck; turning the spindle around and clamping it, clamping the outlet side spindle diameter with a four-jaw chuck, supporting the workpiece at the inlet side support position with a center rest, and machining the inlet side end face and drilling a center hole according to the design drawings.

[0042] In this embodiment, a two-clamping, step-by-step reference transfer strategy is employed to complete the machining of the center hole on the inlet side. The initial clamping uses the outer diameter of the welded flange on the inlet side of the intermediate section as the alignment reference, rather than directly using the outer diameter of the blank. This establishes a coaxial relationship between the alignment reference and the already welded intermediate section, ensuring the consistency between the machining axis of the inlet side and the axis of the machined cavity in the intermediate section from the outset. A mounting position is machined near the shaft diameter in the chuck bearing area. This position serves as a transitional positioning reference for turning the machine, solidifying the axial accuracy established during the initial clamping in a mechanical structure, thus avoiding the risk of losing the reference after turning. During the initial clamping, the four-jaw chuck holds one end of the shaft diameter; after turning, it holds the other end. This provides high alignment flexibility and can adapt to differences in shaft diameter at both ends.

[0043] After being turned and clamped, the inlet-side support is used with a center rest to allow the workpiece to be machined with its end face and center hole drilled around the center rest axis, ensuring the perpendicularity of the inlet-side end face and the coaxiality of the center hole axis with the center rest axis. Since the center rest was precisely aligned with the outer circle of the welded flange during the initial clamping, the center hole axis on the inlet side, after being transferred through the center rest, becomes collinear with the axis of the intermediate section cavity and the axis of the outlet cavity. This scheme, through flange outer circle alignment, center rest fixation, and the center rest supporting the center hole machining reference chain, unifies the axial accuracy accumulated from segmented machining onto the center hole of the entire spindle, providing a unified reference throughout the entire spindle for subsequent double-center finishing of the outer circle.

[0044] In some embodiments provided in this application, machining a center hole on the outlet side of the integral spindle includes the following steps: clamping the outlet side spindle diameter with a four-jaw chuck, supporting the other end with a center point, aligning with the outer circle of the welded flange on the outlet side of the middle section, and machining a support position on the spindle diameter side near the bearing area of ​​the chuck; turning around and clamping, clamping the inlet side spindle diameter with a four-jaw chuck, supporting the workpiece at the outlet side support position with a center rest, and machining the outlet side end face and drilling a center hole according to the design drawings.

[0045] In this embodiment, a two-stage clamping strategy symmetrical to the inlet side is used to complete the machining of the outlet side center hole. The outer diameter of the welded flange on the outlet side of the intermediate section is used as the alignment datum, ensuring that the machining axis on the outlet side is strictly aligned with the axis of the already machined cavity in the intermediate section from the initial setup. A four-jaw chuck clamps the outlet side shaft diameter, and a center supports the other end. This clamping method provides high rigidity support, resulting in higher alignment accuracy and a more reliable datum compared to the blank outer diameter alignment. A mounting position is machined near the shaft diameter in the chuck bearing area, solidifying the axis accuracy established in the initial clamping in a mechanical structure. This prevents datum loss after reversal and provides a repeatable transitional datum for subsequent machining.

[0046] After being turned and clamped, the inlet-side shaft diameter is held in place by a four-jaw chuck, and the outlet-side support is used to rotate the workpiece around the support axis to machine the end face and drill the center hole. This ensures the perpendicularity of the outlet-side end face and the coaxiality of the center hole with the support. Since the support was precisely aligned with the outer circle of the outlet-side welded flange during the initial clamping, the axis of the outlet-side center hole, after being transferred through the support, becomes collinear with the axis of the intermediate section cavity and the axis of the inlet-side center hole. This scheme, together with the inlet-side machining, forms a complete double-end datum closure, ensuring that the axes of the center holes at both ends of the overall spindle are fully unified with the axes of the machined cavities in each section. This provides a high-precision unified datum throughout the entire spindle for subsequent double-center precision machining of the outer circle.

[0047] In some embodiments provided in this application, the positioning stops of the first and second segments are processed and protected as follows: during single-piece processing, a machining allowance of not less than 10mm is left for the axial length of the positioning stop; after the positioning dimension of the outer circle of the stop is inspected and approved, the positioning stop is processed to the axial dimension required by the drawing; during transportation, a fully enclosed nylon protective clip is fitted on the outside of the positioning stop and locked and fixed by the screws on the split face of the clip to prevent the positioning stop from being damaged during transportation.

[0048] In this embodiment, a step-by-step machining strategy of leaving a roughing allowance and then finishing is adopted. A machining allowance of no less than 10mm is reserved in the axial length of the positioning stop, ensuring that the stop is not subject to the final dimensional accuracy constraints during the roughing stage. This avoids dimensional deviations due to uneven blank allowances or tool deflection during clamping. After the outer diameter positioning dimension of the stop passes inspection, it is then finished to the axial dimension required by the drawing. This achieves a machining sequence that prioritizes outer diameter accuracy followed by axial dimension accuracy. It avoids material waste caused by finishing the stop when the outer diameter is unqualified, and ensures that the final axial dimension of the stop meets the standards simultaneously with the outer diameter positioning accuracy, effectively reducing the risk of single-piece scrap.

[0049] During transport, a full-coverage nylon protective clip set is used to position the stop. The clips are secured with split-face screws, forming a complete protective layer for the stop, effectively preventing scratches or dimensional damage to the stop surface caused by collisions or abrasions during hoisting and handling. The nylon material has a certain degree of elasticity, which can buffer external impacts and will not cause indentations on the machined surface of the stop. This protective method is easy to install and remove, and can be reused. While ensuring the safety of the stop during transport, it reduces auxiliary costs and ensures that the stop maintains the accuracy required by the drawings when it arrives at the assembly station, providing a reliable guarantee for the precise positioning of the three-section welding.

[0050] In some embodiments provided in this application, when hoisting a single section of the middle section, a hoisting method using a lifting beam and wire rope is adopted. The lifting beam is an H-shaped lifting beam with multiple lifting lugs and stiffening plates. A support base is provided at the bottom of the lifting beam, and shackles are provided on the lifting lugs.

[0051] In this embodiment, a multi-point lifting method using an H-shaped lifting beam and wire ropes is employed. The H-shaped cross-section has excellent bending stiffness, and combined with multiple lifting lugs and stiffening plates on the lifting beam, the beam's deformation is minimal when bearing the weight of the middle section, ensuring the beam's stability during lifting. Multiple lifting lugs, along with shackles, achieve multi-point suspension, distributing the lifting load of the middle section to multiple stress points. This avoids excessive local stress or bending deformation of the workpiece due to concentrated loads during single-point lifting, making it particularly suitable for situations where the middle section is long and the risk of deflection due to its own weight is high. The shackle connection method is convenient to install and remove, and the locking is reliable, facilitating rapid execution and safe release of lifting operations.

[0052] The lifting beam is equipped with a support base at its bottom, providing bottom support for the intermediate section during hoisting. This, combined with the multi-point suspension at the top, creates vertical constraints, placing the intermediate section in a near-simply supported beam stress state in the air. This effectively suppresses self-weight deflection and axial misalignment caused by excessive cantilever length. The support base has a large contact area with the outer circle of the intermediate section, resulting in uniform pressure distribution and preventing localized damage to the machined surfaces of the workpiece. This hoisting scheme structurally addresses the triple requirements of lifting rigidity, load distribution, and workpiece protection, ensuring that the machined cavities and outer circle accuracy of the intermediate section remain undamaged throughout the entire process of single-piece transfer to the welding assembly station. This provides reliable workpiece condition assurance for subsequent stop positioning welding.

[0053] In some embodiments provided in this application, the machining of the internal cavity of the intermediate section specifically includes: providing a tool holder, fixing the tool holder to the lathe tool holder with a set screw through an arc-shaped tool holder, determining the counterweight position at one end of the tool holder through finite element analysis and adding a counterweight, and machining the internal cavity of the intermediate section using the tool holder.

[0054] In this embodiment, a specialized clamping method using a tool holder and an arc-shaped tool post is employed to machine the internal cavity of the intermediate section. The arc-shaped tool post is fixed to the tool post by set screws, allowing for flexible adjustment of the tool holder's extension angle and axial position to adapt to machining requirements at different axial depths within the intermediate section's internal cavity. Compared to straight shank tool holders, this method offers a wider range of process adaptability. The counterweight position is determined through finite element analysis, rather than relying on empirical estimation. This allows for precise calculation of the tool holder's deformation modes and unbalanced torque distribution under cutting forces, ensuring that the counterweight's mass and installation position accurately match the actual stress state of the tool holder. This achieves dynamic balance of the tool holder system from a mechanical perspective.

[0055] During machining, the counterweight effectively counteracts the deflection and vibration of the tool holder's overhang caused by cutting forces, suppressing common deep-hole machining phenomena such as tool deflection and vibration, and ensuring the straightness and wall thickness uniformity of the internal cavity. The tool holder cuts into the workpiece in a stable, balanced state, ensuring that the axis of the internal cavity and the outer circle of the intermediate section maintain the same center of rotation throughout the machining process, guaranteeing that the internal cavity and the outer circle meet the first coaxiality requirement. This solution incorporates finite element analysis into the tool system design, using data to drive the counterweight layout, so that the machining accuracy of deep cavities no longer depends on the operator's experience, improving the consistency and reliability of the intermediate cavity machining.

[0056] like Figures 2 to 11 As shown, in a specific embodiment, the main shaft of the air-storage axial compressor includes a left section 100, a middle section 110, and a right section 120. Each of the three sections has a weight-reducing cavity 130. Adjacent sections are positioned by a stop 140, and a welded bevel 142 connects to the stop 140. The outer diameter 170 of the large end is located at the connection between the left section 100 and the right section 120 of the main shaft and the middle section 110. A tool holder 160 equipped with a counterweight structure 162 is used to machine the internal cavity of the middle section. When hoisting the middle section 110, a lifting beam 150 is used with wire ropes. The lifting beam 150 is an H-shaped beam with multiple lifting lugs 152 and stiffening plates 154. A support base 156 is located at the bottom of the lifting beam 150, and shackles 158 are provided on the lifting lugs 152.

[0057] This application provides a machining method for a three-section welded air storage axial flow compressor spindle, which optimizes the original spindle left section, spindle middle section, spindle right section, and overall spindle process as follows: 1. Solve the problems of the stop, welding bevel, and coaxiality of the weight reduction cavity of the spindle with the weight reduction cavity structure on the left and right end faces of the spindle.

[0058] By extending the sleeve, without first machining the end face of the weight reduction cavity, a four-jaw chuck is used to clamp and align the small end, then the large end shaft diameter is mounted, and the small end support position is machined. A four-jaw chuck is used to clamp and align the large end, then the small end shaft diameter support position is mounted. After alignment, the small end end face is flattened, and the small end center hole is machined. Similarly, the large end center hole is machined, and then a lathe chuck is used to clamp the spindle, and the left and right sections of the spindle are machined using the center. Before the center is removed, the center rest is brought into contact with the outer diameter of the large end of the spindle. After complete contact and alignment, the center is disengaged from the spindle. This method uses the precision of the center to achieve rapid alignment of the center rest. The weight reduction cavity is machined using a chuck in conjunction with the center rest. The specific scheme is as follows: 1) A four-jaw chuck is used to clamp and align the small end, then the large end shaft diameter is mounted, and the small end support position is machined. 2) Using a four-jaw chuck, clamp and align the large end, then position the small end shaft diameter support. After alignment, flatten the small end face and machine the small end center hole. 3) Using a four-jaw chuck, clamp the small end center, clamp and align the large end shaft diameter. a) Leave a 1mm allowance on each side for semi-finish turning of all parts; b) Finish turn all parts. 4) Clamp the small end, and position the large end center. a) Finish turn the large end outer diameter, ensuring the remaining unmachined areas meet the drawing requirements; b) Finish turn the bevel, stop, and chamfer, leaving a 10mm allowance for the axial length of the stop for subsequent measurement; c) Finish turn the large end face and chamfer. 5) Clamp the small end with the chuck, and position the large end center support for the large outer diameter. Use a dial indicator to align, ensuring coaxiality ≤0.01mm; finish turn the weight reduction cavity according to the drawing. 6) Cooperate with the inspector to check the outer diameter and inner hole, ensuring coaxiality ≤0.01mm.

[0059] 2. To solve the problem that after the integral spindle is welded, the weight reduction cavity and inner hole are not connected to the outside, so the inner hole after the three sections of the spindle are welded cannot meet the coaxiality requirements by machining the inner hole weight reduction cavity and the outer circle in the same way according to the conventional process plan, and the coaxiality is difficult to guarantee. Since the machining datum for the left section, middle section, and right section of the spindle, as well as the bevel and inner hole, are all the large outer diameter at the joint of the single-section spindle, the above-mentioned scheme is used during single-piece machining. This ensures that the coaxiality of the joint, weight-reducing cavity, and outer diameter is ≤0.01mm. Therefore, when drilling the center hole for machining the integral spindle, the large outer diameter at the joint of the split spindle should be used as the datum for dial indicator alignment. This ensures that the coaxiality of the machined inner hole, weight-reducing cavity, joint, and outer diameter of the integral spindle is controlled within 0.02mm. The specific scheme is as follows: Use a four-jaw chuck to clamp the inlet side shaft diameter, with the other end supported by a center. Align with the outer diameter of the welded flange on the inlet side of the middle section, near the shaft diameter side of the chuck bearing area, at the frame position. Using a four-jaw chuck to clamp the shaft diameter on the exit side, and with the center rest supporting the workpiece at the inlet side support position, machine the inlet side end face according to the design drawings and drill a center hole; using a four-jaw chuck to clamp the shaft diameter on the exit side, align with the outer circle of the welded flange on the middle section of the exit side, and support the workpiece at the other end with a center point, and position the support near the chuck bearing area on the shaft diameter side. Using a four-jaw chuck to clamp the shaft diameter on the inlet side, and with the center rest supporting the workpiece at the exit side support position, machine the exit side end face according to the design drawings and drill a center hole; with centers on both sides supporting the workpiece, and jaws assisting in clamping, proceed with subsequent machining.

[0060] 3. Machining solution for the nearly 5-meter inner hole in the middle section of the spindle: Design a connection method that fixes the tool holder with an arc-shaped tool post set screw, install it on the turning tool post, and then determine the position of the counterweight at the left end of the tool holder through ANSYS finite element analysis, and use the counterweight to improve the stability of the tool holder.

[0061] 4. The left section, middle section, and right section of the spindle adopt a stop fit, and the axial and radial thickness of the stop is only 2mm. The tolerances of the inner hole and outer circle at the stop are very strict. Measurement and inspection are required after machining. However, due to the thin structure, it is difficult to measure with measuring tools. The stop is the guarantee for the docking and positioning between spindles. Therefore, the form and position tolerance of the stop must be guaranteed. However, its structure is thin and it is easily damaged during transportation. Therefore, a stop protection plan should be developed during machining and transportation. When machining the left, middle, and right sections of the spindle individually, a 10mm allowance is reserved in the axial length of the locating stop to facilitate measurement. This allowance is maintained after the outer diameter of the locating stop has passed inspection before machining the locating stop according to the drawings. A protective fixture is designed for the transfer of individual spindle parts. The clamp is designed as a full enclosure and secured with screws on the center face of the clamp to reduce the risk of movement between the clamp and the workpiece during transport. Considering the thin structure of the locating stop area, the clamp is made of nylon to prevent damage to the stop from bumps and tooling movement during transport, ensuring the locating stop remains intact during transit.

[0062] 5. The total axial distance of the weight-reducing cavity on the right section of the spindle is nearly 500mm, resulting in insufficient tool rigidity during lathe machining. This solution involves machining the weight-reducing cavity in stages, using a combination of turning and boring. The smaller end is chuckled and aligned on the lathe, with the outer diameter supported by a horizontal lathe bracket. Alignment is achieved by using a dial indicator to straighten and align the already machined outer diameter near the larger end, requiring a deviation ≤0.01mm. The first layer of weight-reducing cavity near the larger end face is then machined by turning. Alignment is achieved using the inner hole of the flange on the right section of the spindle, and the shaft is straightened along the spindle axis, requiring a dial indicator value ≤0.01mm. The second layer of weight-reducing cavity is then machined by boring.

[0063] 6. The middle section of the main shaft, in its single-piece state, has no dedicated hoisting position and is very heavy, weighing 36.225 tons. Its irregular shape also makes the transfer and hoisting during processing and assembly a challenge. A hoisting fixture is designed to achieve stable and safe hoisting of the middle section of the main shaft by using an H-shaped lifting beam and steel wire rope.

[0064] In this application, the term "multiple" refers to two or more unless otherwise expressly defined. The terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; "linking" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0065] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0066] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for machining the main shaft of a three-section welded air-storage axial-flow compressor, wherein the main shaft comprises a first section, a middle section, and a second section, each section having a weight-reducing cavity inside, and adjacent sections being positioned by a stop joint, characterized in that... Includes the following steps: For the first and second sections, the end weight reduction cavities are reserved and not machined. The positioning end faces and center holes are machined at both ends of the workpiece. Then, the workpiece is clamped by chuck and center, and the stop and welding bevel of the section are machined. Keep the center in the supporting position, bring the support component into contact with the outer circle of the workpiece and adjust it to be coaxial with the center axis, then remove the center so that the support center of the support component coincides with the center axis; The weight-reducing cavity of this section is machined by using a chuck in conjunction with the mounting method of the supporting component, so that the stop, the welding bevel, the weight-reducing cavity and the outer circle of this section have a first coaxiality; A tool holder equipped with a counterweight structure is used to machine the internal cavity of the middle section, so that the internal cavity and the outer circle of the section have the first coaxiality; The first section, the middle section, and the second section are positioned by the stop and then welded together as one piece; Center holes are machined at both ends of the integral spindle, and the axis of the center holes at both ends is collinear with the axis of each machined cavity. Using the center holes at both ends of the integral spindle as positioning references, the workpiece is supported by a double center method to complete the outer circle machining of the integral spindle, so that the integral outer circle and the internal machined cavity have a second coaxiality. The second coaxiality is the target coaxiality requirement of the integral spindle.

2. The machining method for the main shaft of the three-section welded air-storage axial flow compressor according to claim 1, characterized in that, For the first and second segments, machining the positioning end faces and center holes includes the following steps: A four-jaw chuck is used to hold and align the small end, a center frame is erected to support the large end shaft diameter, and the small end frame position is machined out. A four-jaw chuck is used to hold and align the large end, a center frame is set up to support the small end frame, the small end face is flattened after alignment, and the small end center hole is machined. The small end is clamped with a center, and a four-jaw chuck is used to clamp and align the large end shaft diameter. After alignment, the large end face is flattened, and the center hole of the large end is machined.

3. The machining method for the main shaft of the three-section welded air-storage axial flow compressor according to claim 2, characterized in that, For the first and second sections, the machining of the stop and welding bevel includes the following steps: The large end is clamped at the top, and a four-jaw chuck is used to hold the small end position, and the outer circle of the large end is machined out. The car exits the bevel, stop, and chamfer, with a allowance reserved at the stop; Finish machining of the large end face and chamfer.

4. The machining method for the main shaft of the three-section welded air-storage axial flow compressor according to claim 3, characterized in that, For the first and second segments, the processing of the weight-reducing cavity includes the following steps: Keep the center in the top position, align the center support with the outer diameter of the large end of the spindle, and remove the center after alignment. The small end is clamped by a chuck, and the outer circle of the machined large end is supported by a center frame. The coaxiality is ensured to be ≤0.01mm by using a dial indicator. The weight reduction cavity is machined according to the drawings.

5. The machining method for the main shaft of the three-section welded air-storage axial flow compressor according to claim 4, characterized in that, The deep weight reduction cavity of the second section is machined using a combination of turning and boring. The deep weight reduction cavity is divided into a first layer and a second layer along the axial direction. The combination of turning and boring includes the following steps: Clamp the small end on the lathe and align it. Support it on the outer circle with a horizontal lathe bracket. Use the machined outer circle of the large end as a reference to straighten and align it. The alignment accuracy is ≤0.01mm. Then machine the first weight reduction cavity near the large end face. The boring process is adopted, with the inner hole of the second flange section as the alignment point, and the spindle is straightened along the spindle axis. The alignment accuracy is ≤0.01mm using a dial indicator, and the second layer of weight reduction cavity is boring.

6. The machining method for the main shaft of a three-section welded air-storage axial-flow compressor according to claim 1, characterized in that, The integral spindle includes an inlet side and an outlet side. Machining the center hole on the inlet side of the integral spindle includes the following steps: The inlet side shaft diameter is held in place by a four-jaw chuck, and the other end is supported by a center. The outer circle of the welded flange on the inlet side of the middle section is used for alignment. The frame position is machined out at the shaft diameter near the bearing area of ​​the chuck. Turn the workpiece around and clamp it, using a four-jaw chuck to hold the outlet side shaft diameter, and a center rest to support the workpiece at the inlet side support position. Then, turn the inlet side end face according to the design drawings and drill a center hole.

7. The machining method for the main shaft of a three-section welded air-storage axial-flow compressor according to claim 6, characterized in that, Machining the center hole on the exit side of the integral spindle includes the following steps: The four-jaw chuck clamps the shaft diameter on the outlet side, and the other end is supported by the center. The outer circle of the welded flange on the outlet side of the middle section is aligned, and the frame position is machined out on the shaft diameter side near the bearing area of ​​the chuck. Turn the workpiece around and clamp it, using a four-jaw chuck to hold the inlet side shaft diameter, and a center rest to support the workpiece at the outlet side support position. Then, turn the outlet side end face according to the design drawings and drill a center hole.

8. The machining method for the main shaft of a three-section welded air-storage axial-flow compressor according to claim 1, characterized in that, The following processing and protection methods are used for the positioning stops of the first and second sections: When machining a single piece, leave a machining allowance of not less than 10mm for the axial length of the positioning stop; After the outer circle positioning dimension of the stop is inspected and approved, the positioning stop is then machined to the axial dimension required by the drawing. During transport, a fully enclosed nylon protective clip is fitted over the positioning stop and secured with screws on the split face of the clip to prevent damage to the positioning stop during transport.

9. The machining method for the main shaft of a three-section welded air-storage axial-flow compressor according to claim 1, characterized in that, When hoisting a single section in the middle, a hoisting beam is used in conjunction with a wire rope. The hoisting beam is an H-shaped beam with multiple lifting lugs and stiffening plates. The bottom of the hoisting beam is equipped with a support base, and the lifting lugs are equipped with shackles.

10. A method for machining the main shaft of a three-section welded air-storage axial-flow compressor according to any one of claims 1 to 9, characterized in that, The specific processing of the internal cavity of the intermediate section includes: A tool holder is provided and fixed to the lathe tool post with a set screw via an arc-shaped tool post. The position of the counterweight is determined by finite element analysis at one end of the tool holder and a counterweight is added. The tool holder is used to machine the internal cavity of the middle section.

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