Clamp and processing method for processing straight edge section of very thin wall metal bellows

Abstract

The present application relates to the technical field of bellows processing, in particular to a clamp for processing straight edge section of thin-wall metal bellows and a processing method thereof, comprising a receiving main body, a pressing structure, an expanding structure and a limiting structure. The second groove of the receiving main body is used for placing the metal bellows assembly. The pressing structure is sleeved on another straight edge section of the metal bellows assembly, and the pressing structure and the receiving main body are fixedly connected through fasteners to form a clamp main body for clamping the metal bellows assembly. The two straight edge sections of the metal bellows assembly are arranged to extend outward along the axial direction to protrude from the clamp main body. The expanding structure extends into the clamp main body to expand the two straight edge sections of the metal bellows assembly from the inside and abut against the axial end face one of the step and the axial end face two of the pressing structure, respectively. The clamp meets the requirements of processing and clamping fixation of the straight edge section, and there are no clamping marks on the inner and outer surfaces of the metal bellows assembly, which can ensure the processing efficiency and the qualified rate of the product.

Description

Technical Field

[0001] This invention relates to the field of corrugated pipe processing technology, and in particular to a fixture and processing method for processing the straight edge section of an ultra-thin-walled metal corrugated pipe. Background Technology

[0002] Bellows-type mechanical seals are widely used in liquid rocket engine turbopump sealing devices due to their excellent performance, high reliability, and suitability for high-speed, high-pressure, high-temperature, and low-temperature operating conditions. These bellows are sealing bellows, typically with a WW (Wide-Wide) interface. This means the WW interface consists of a metal bellows with straight edges on both sides, welded to the end flanges on both sides of the turbopump shaft to form a seal inside the shaft, preventing external liquid, gas, or oxygen from entering.

[0003] To ensure the bellows does not contact the rotating shaft during installation, the coaxiality of the two straight edges must not exceed ∅0.3mm. Simultaneously, to guarantee welding quality, the length tolerance of the two straight edges must be only 0.2mm. While ensuring these two key technical indicators, the inner and outer surfaces of the bellows must also be smooth and intact. In practical applications, the bellows does not need to provide sealing pressure; the initial state of the bellows during installation is a free state without compression or tension. Therefore, the sealing bellows have relatively low design stiffness, fewer wave numbers, smaller wave pitch, and shorter effective length. In manufacturing, multi-layered ultra-thin-walled tube blanks (the tube blank is a single layer of stainless steel material with a wall thickness of less than 0.2mm) are often used, resulting in high flexibility for the sealing bellows.

[0004] In existing publicly available metal bellows cutting and processing technologies, the methods for clamping and fixing the bellows include multi-lobed radial support and fixing from the inside of the bellows, and partial radial clamping and fixing from the outside of the bellows. However, neither of these methods is suitable for extremely thin-walled sealing bellows with strict surface quality requirements. This is because, during the clamping process, the existing clamping methods are very likely to produce clamping marks on the extremely thin-walled sealing bellows that are difficult to handle. The straight edge section of the extremely thin-walled sealing bellows is produced by cutting, and the existing methods for cutting extremely thin-walled sealing bellows generally use turning. The processing method of turning only once leads to the technical problem of difficulty in obtaining the precise dimensions of the bellows, and it is also impossible to meet the processing requirements of the precise dimensions of the straight edge section of the extremely thin-walled bellows. Consequently, it is impossible to guarantee the inner and outer surface quality of the bellows and the coaxiality of the two straight edges, which greatly reduces the production efficiency and product qualification rate of extremely thin-walled bellows. Summary of the Invention

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a fixture and processing method for machining the straight edge section of ultra-thin-walled metal bellows. It solves the technical problems that the existing clamping method is prone to producing clamping marks that are difficult to handle on ultra-thin-walled sealed bellows, and that the turning processing method cannot meet the precision dimension processing of the straight edge section of ultra-thin-walled bellows.

[0006] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0007] In a first aspect, embodiments of the present invention provide a fixture for processing the straight edge section of an ultra-thin-walled metal corrugated pipe, comprising a receiving body, a clamping structure, an expansion structure, and a limiting structure;

[0008] The limiting structure has a first groove on one end face, and one end of the receiving body can be embedded in the first groove. The receiving body has a cylindrical through groove on one end face, and a second groove is formed radially outward at one end of the cylindrical through groove. A step is formed between the second groove and the cylindrical through groove. The second groove is used to place the metal corrugated pipe assembly.

[0009] The clamping structure is fitted onto another straight edge section of the metal bellows assembly, and the clamping structure and the receiving body are fixedly connected by fasteners to form a clamping body for clamping the metal bellows assembly. The clamping structure is used to block the second groove and form an annular space between the second groove that can accommodate the metal bellows assembly. The metal bellows assembly has two oppositely arranged straight edge sections, and the two straight edge sections extend outward along the axial direction to protrude from the clamping body.

[0010] The expansion structure extends into the clamp body to expand the two straight edges of the metal bellows assembly from the inside, respectively abutting against the axial end face one of the step and the axial end face two of the pressing structure. The expansion structure passes through the clamp body and fixes the clamp body in the first groove of the limiting structure. The receiving body, the pressing structure, the expansion structure and the limiting structure are coaxially arranged.

[0011] Optionally, the receiving body is a disc-shaped structural component, and the receiving body has a first end face and a second end face that are disposed opposite to each other;

[0012] The first end face is provided with a positioning groove and a plurality of threaded holes spaced apart along its circumference.

[0013] Optionally, the clamping structure is a disc-shaped structural component. A positioning block is provided on one end face of the clamping structure near the receiving body along its axial direction. The positioning block is engaged with the positioning groove. A through hole is provided on the clamping structure at the position corresponding to the threaded hole. The fastener passes through the through hole and is locked in the threaded hole. A central connecting hole is provided at the center position of the clamping structure. The central connecting hole is used to accommodate the other straight edge section of the metal bellows assembly and for the extension of the expansion structure.

[0014] Optionally, the tightening structure includes a tightening ring, a first limiting cone, a second limiting cone, and a tightening screw;

[0015] The expansion ring is located inside the metal bellows assembly, and the outer side wall of the expansion ring abuts against the two straight edge segments respectively. The expansion ring has a central mounting hole, and the first limiting cone and the second limiting cone are located on both sides of the central mounting hole respectively. The first limiting cone is inserted into one side of the central mounting hole, and the second limiting cone is inserted into the other side of the central mounting hole. The first limiting cone and the second limiting cone are interlocked and locked by the expansion screw.

[0016] Optionally, the expansion ring is made of polyurethane and includes a cylindrical part, with abutment rings integrally formed at both the upper and lower ends of the cylindrical part along its radial outward direction.

[0017] Both ends of the central mounting hole are formed with inclined insertion ports, and the inclined portions of the first limiting cone and the second limiting cone abut against the inclined insertion ports.

[0018] Optionally, the first limiting cone includes an integrally formed first frustum and a first vertical cylinder, and the diameter of the first vertical cylinder is equal to the diameter of the bottom end face of the first frustum. The first vertical cylinder extends from one side of the expansion ring into the central mounting hole so that the inclined portion of the first frustum abuts against the inclined insertion port at the upper end. A vertical hole is formed on the first frustum, and a slot is formed on the bottom end face of the first vertical cylinder. The slot is connected to the vertical hole, and the expansion screw passes through the vertical hole and the slot, forming a receiving space between them.

[0019] The second limiting cone includes a second frustum and a second vertical cylinder. The diameter of the second vertical cylinder is smaller than the diameter of the top end face of the second frustum. The second vertical cylinder extends into the central mounting hole from the other side of the expansion ring, so that the inclined portion of the second frustum abuts against the inclined insertion port at the lower end. A screw insertion hole is provided on the second vertical cylinder, so that the second vertical cylinder forms an annular cylindrical wall. The annular cylindrical wall can be inserted into the receiving space. The bottom of the expansion screw can be inserted into and fixed in the screw insertion hole.

[0020] The bottom end face of the second frustum extends downward along its axial direction to form a square limiting block.

[0021] Optionally, the limiting structure is a disc-shaped structure, and a square hole communicating with the first groove is opened at the center of the limiting structure, and the square hole is inserted into the square limiting block.

[0022] Optionally, the first groove of the limiting structure is provided with an annular receiving groove for accommodating one side of the straight edge segment.

[0023] Optionally, the fastener includes a plurality of fastening screws, which are screwed into the threaded hole.

[0024] Secondly, a processing method for machining straight edge sections of ultra-thin-walled metal bellows, the method being based on the aforementioned fixture for machining straight edge sections of ultra-thin-walled metal bellows, the method comprising the following steps:

[0025] S1. Cut the straight edge sections on both sides of the metal bellows assembly, leaving a machining allowance, to obtain the rough-machined metal bellows assembly.

[0026] S2. Place the corrugated section of the rough-machined metal bellows assembly from S1 into the cylindrical through groove, so that the straight edge section on one side of the metal bellows assembly protrudes outward relative to the receiving body.

[0027] S3. The metal bellows assembly in S2 is fitted together using a clamping structure so that the straight edge section on the other side of the metal bellows assembly protrudes outward relative to one side of the clamping structure.

[0028] S4. The clamping structure and the receiving body are fixedly connected by fasteners to form a clamping body for clamping the metal bellows assembly;

[0029] S5. Use calipers to measure the thickness evenly along the circumferential edge of the fixture body, and the thickness measurements should be consistent.

[0030] S6. Place the fixture body into the flat limiting structure;

[0031] S7. The expansion structure is passed through the inner cavity of the bellows and fixed to the limiting structure, and the expansion structure is expanded radially along the metal bellows assembly so that the expansion structure abuts the straight edge sections on both sides of the metal bellows assembly against the fixture body.

[0032] S8. Remove the fixture body from the limiting structure and place it on the chuck of the lathe;

[0033] S9. Control the cutting tool to machine the straight edge section of the metal bellows on the exposed side of the fixture body until the exposed straight edge section is completely removed.

[0034] S10. Then remove the main body of the fixture, change the machining side, re-clamp it, and perform turning on the straight edge section on the other side. Repeat the above operations S1-S9.

[0035] The beneficial effects of the present invention are as follows: The present invention provides a fixture and processing method for processing the straight edge section of an ultra-thin-walled metal corrugated pipe, namely a split fixture. The rough-machined metal corrugated pipe assembly is placed in the second groove, and the clamping structure is compressed along the axial direction of the metal corrugated pipe assembly as a whole. The limiting inner hole of the clamping structure and the receiving body is fitted with the outer diameter of the straight edge section of the metal corrugated pipe assembly, and the contact length is the required processing dimension of the straight edge. In this way, when the metal corrugated pipe assembly is compressed, the circumferential plane of the two ends of the corrugated pipe is in close contact with the inner wall of the annular space, and the part of the straight edge section that is exposed is the removal length. At the same time, the inner cavity of the metal corrugated pipe assembly is expanded and tightened by the expansion structure, thereby realizing the clamping and fixing of the metal corrugated pipe assembly. Although the clamp of the present invention has two halves, both halves are integral structures, and the clamping principle is based on the springback characteristics of the metal bellows assembly. It not only meets the requirements for clamping and fixing the straight edge section, but also leaves no clamping marks on the inner and outer surfaces of the metal bellows assembly. At the same time, it does not require a chip removal and absorption device, which can ensure both product processing efficiency and product qualification rate.

[0036] Furthermore, the fixture for machining the straight edge section of ultra-thin-walled metal bellows of the present invention, combined with a novel machining method, requires first rough machining of the metal bellows assembly, and then clamping the rough-machined metal bellows assembly with the fixture to expose the part to be cut to the outside, and directly cutting it with a lathe tool to ensure the machining accuracy of the straight edge section of the metal bellows assembly. It is suitable for the machining and manufacturing of ultra-thin-walled precision metal bellows with high surface quality requirements, small diameter, low rigidity, small effective length, small wave pitch, and unlimited number of layers, and is especially suitable for the precision machining of the straight edge section of ultra-thin-walled bellows. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the present invention for rough machining of the straight edge section of an ultra-thin-walled metal corrugated pipe;

[0038] Figure 2 for Figure 1 A magnified view of the details at point "A" circled in the image;

[0039] Figure 3 This is a schematic diagram of the overall structure of the fixture for machining the straight edge section of an ultra-thin-walled metal bellows according to the present invention;

[0040] Figure 4 for Figure 3 A magnified view of the details at point "B" circled in the image;

[0041] Figure 5 for Figure 3 Schematic diagram of the middle section;

[0042] Figure 6 for Figure 3A schematic diagram of the structure of the middle clamp (with lower limit structure) clamping on the lathe;

[0043] Figure 7 for Figure 6 A magnified view of the details at the circled "E";

[0044] Figure 8 This is a schematic diagram of the dimensions of a metal bellows assembly after the straight-edge section has been processed.

[0045] Explanation of reference numerals in the attached figures

[0046] 1. Receiving body; 11. Cylindrical through groove; 13. Positioning groove; 14. Threaded hole; 15. First end face; 16. Second end face; 12. Second groove; 2. Clamping structure; 21. Positioning block; 22. Through hole; 23. Central connecting hole; 3. Expansion structure; 31. Expansion ring; 311. Central mounting hole; 312. Cylindrical part; 313. Abutting ring part; 314. Inclined insertion port; 32. First limiting cone; 321. First frustum; 3211. Vertical hole; 322. First vertical cylinder; 3221. Slot; 3 3. Second limiting cone; 331. Second frustum; 3311. Square limiting block; 332. Second vertical cylinder; 3321. Screw socket; 34. Expansion screw; 35. Accommodation space; 4. Limiting structure; 41. First groove; 42. Annular accommodating groove; 43. Square hole; 5. Fastener; 51. Fastening screw; 100. Metal bellows assembly; 101. Straight edge section; 200. Chuck; 300. Support spindle; 400. Rolling cutting limiting ring; 500. Rolling cutting mechanism; 501. Rolling cutting blade; 600. Lathe tool. Detailed Implementation

[0047] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0048] See Figures 1-8 As shown in the figure, a fixture for processing the straight edge section of an ultra-thin-walled metal corrugated pipe according to an embodiment of the present invention includes a receiving body 1, a clamping structure 2, an expansion structure 3, and a limiting structure 4.

[0049] The limiting structure 4 has a first groove 41 on one end face, and one end of the receiving body 1 can be embedded in the first groove 41. The receiving body 1 has a cylindrical through groove 11 on one end face, and a second groove 12 is formed radially outward at one end of the cylindrical through groove 11. A step is formed between the second groove 12 and the cylindrical through groove 11. The second groove 12 is used to place the metal bellows assembly 100.

[0050] The clamping structure 2 is fitted onto another straight edge section 101 of the metal bellows assembly 100, and the clamping structure 2 and the receiving body 1 are fixedly connected by fasteners 5 to form a clamping body for clamping the metal bellows assembly 100. The clamping structure 2 is used to block the second groove 12 and form an annular space between the second groove 12 that can accommodate the metal bellows assembly 100. The metal bellows assembly 100 has two oppositely arranged straight edge sections 101, and the two straight edge sections 101 extend outward along the axial direction to protrude from the clamping body.

[0051] The expansion structure 3 extends into the fixture body to expand the two straight edge segments 101 of the metal bellows assembly 100 from the inside, respectively abutting against the axial end face one of the step and the axial end face two of the clamping structure 2. The expansion structure 3 passes through the fixture body and fixes the fixture body in the first groove 41 of the limiting structure 4. The receiving body 1, the clamping structure 2, the expansion structure 3 and the limiting structure 4 are coaxially arranged.

[0052] Furthermore, the receiving body 1 is a disc-shaped structural component, having a first end face 15 and a second end face 16 disposed opposite to each other. The first end face 15 has a positioning groove 13 and a plurality of threaded holes 14 spaced apart along its circumference. This facilitates the rapid installation and positioning of the clamping structure 2 and the receiving body 1.

[0053] Furthermore, the clamping structure 2 is a disc-shaped structure. A positioning block 21 is provided on one end face of the clamping structure 2 near the receiving body 1 along its axial direction. The positioning block 21 is engaged with the positioning groove 13. A through hole 22 is provided on the clamping structure 2 at the position corresponding to the threaded hole 14. The fastener 5 passes through the through hole 22 and is locked in the threaded hole 14. A central connecting hole 23 is provided at the center position of the clamping structure 2. The central connecting hole 23 is used to install the other straight edge section 101 of the metal bellows assembly 100 and to allow the expansion structure 3 to extend.

[0054] Furthermore, the tightening structure 3 includes a tightening ring 31, a first limiting cone 32, a second limiting cone 33, and a tightening screw 34. The tightening ring 31 is located inside the metal bellows assembly 100, and the outer side wall of the tightening ring 31 abuts against two straight edge sections 101 respectively. The tightening ring 31 has a central mounting hole 311. The first limiting cone 32 and the second limiting cone 33 are located on both sides of the central mounting hole 311 respectively. The first limiting cone 32 is partially inserted into one side of the central mounting hole 311, and the second limiting cone 33 is partially inserted into the other side of the central mounting hole 311. The first limiting cone 32 and the second limiting cone 33 are interlocked and locked by the tightening screw 34.

[0055] Furthermore, the expansion ring 31 is made of polyurethane and includes a cylindrical portion 312. Abutment ring portions 313 are integrally formed at both the upper and lower ends of the cylindrical portion 312, extending radially outwards. Inclined insertion ports 314 are formed at both the upper and lower ends of the central mounting hole 311, and the inclined portions of the first limiting cone 32 and the second limiting cone 33 abut against the inclined insertion ports 314. Further tightening of the expansion screw 34 causes the polyurethane expansion ring 31 to expand radially along the metal bellows assembly 100, forming a single clamping structure with all other parts except the limiting structure 4. Then, the single clamping structure is removed, ready for the next processing step.

[0056] Furthermore, the first limiting cone 32 includes an integrally formed first frustum 321 and a first vertical cylinder 322, and the diameter of the first vertical cylinder 322 is equal to the diameter of the bottom end face of the first frustum 321. The first vertical cylinder 322 extends from one side of the expansion ring 31 into the central mounting hole 311 so that the inclined portion of the first frustum 321 abuts against the inclined insertion port 314 at the upper end. A vertical hole 3211 is provided on the first frustum 321, and a slot 3221 is provided on the bottom end face of the first vertical cylinder 322. The slot 3221 is connected to the vertical hole 3211. The expansion screw 34 passes through the vertical hole 3211 and the slot 3221 and forms a receiving space 35 between the slot 3221 and the expansion screw 34.

[0057] The second limiting cone 33 includes a second frustum 331 and a second vertical cylinder 332. The diameter of the second vertical cylinder 332 is smaller than the diameter of the top end face of the second frustum 331. The second vertical cylinder 332 extends from the other side of the expansion ring 31 into the central mounting hole 311, so that the inclined portion of the second frustum 331 abuts against the inclined insertion port 314 at the lower end. The second vertical cylinder 332 is provided with a screw insertion hole 3321, so that the second vertical cylinder 332 forms an annular cylindrical wall. The annular cylindrical wall can be inserted into the receiving space 35, and the bottom of the expansion screw 34 can be inserted and fixed in the screw insertion hole 3321. The bottom end face of the second frustum 331 extends downward along its axial direction to form a square limiting block 3311.

[0058] It should be noted that this structure is easy to install and disassemble, and its operation is simple with high positioning accuracy. It also provides good tensioning effect.

[0059] Furthermore, the limiting structure 4 is a disc-shaped structure, and a square hole 43 communicating with the first groove 41 is opened at the center of the limiting structure 4. The square hole 43 is inserted into the square limiting block 3311. This ensures the tightening effect of the tightening structure 3 and thus improves the machining accuracy of the straight edge section 101.

[0060] Furthermore, the first groove 41 of the limiting structure 4 is provided with an annular receiving groove 42 for accommodating one side of the straight edge segment 101. The purpose is to better accommodate the straight edge segment 101 on the side waiting to be processed and to prevent the straight edge segment 101 from deforming.

[0061] Furthermore, the fastener 5 includes multiple fastening screws 51, which are screwed into the threaded holes 14. It should also be noted that the clamping structure 2 and the receiving body 1 are fastened together using the fastener 5 to form the fixture body. Then, the thickness is measured at three points evenly distributed along the circumferential edge of the fixture body using calipers. The thickness measurements should be consistent. This step is to ensure the fastening effect between the receiving body 1 and the clamping structure 2, further ensuring cutting accuracy.

[0062] A machining method for processing straight edge sections of ultra-thin-walled metal bellows, the method being based on a fixture for processing straight edge sections of ultra-thin-walled metal bellows, and the method comprising the following steps:

[0063] S1. Cut the straight edge segments 101 on both sides of the metal bellows assembly 100, leaving a certain machining allowance, to obtain the rough-machined metal bellows assembly 100.

[0064] S2. Place the corrugated section of the rough-machined metal bellows assembly 100 in the cylindrical through groove 11 so that the straight edge section 101 on one side of the metal bellows assembly 100 protrudes outward relative to the receiving body 1.

[0065] S3. The metal bellows assembly 100 in S2 is fitted into place by the clamping structure 2, so that the straight edge section 101 on the other side of the metal bellows assembly 100 protrudes outward relative to one side of the clamping structure 2.

[0066] S4. The clamping structure 2 and the receiving body 1 are fixedly connected by fasteners 5 to form the clamping body of the metal bellows assembly 100.

[0067] S5. Use calipers to measure the thickness evenly along the circumferential edge of the fixture body. The thickness measurements should be consistent.

[0068] S6. Place the fixture body into the flat limiting structure 4.

[0069] S7. The expansion structure 3 is passed through the inner cavity of the bellows and fixed to the limiting structure 4. The expansion structure 3 is expanded radially along the metal bellows assembly 100 so that the expansion structure 3 abuts the straight edge sections 101 on both sides of the metal bellows against the fixture body.

[0070] S8. Remove the fixture body from the limiting structure 4 and place it on the lathe chuck 200.

[0071] S9. Control the cutting tool 600 to machine the straight edge section 101 on one side of the exposed metal bellows assembly 100 of the fixture body until the exposed straight edge section 101 is completely removed. Figure 6 As shown, the entire clamping structure is installed on the lathe three-jaw chuck 200. The runout is adjusted and measured. The cutting tool 600 is controlled to turn the exposed straight edge section of the corrugated pipe on one side of the entire clamping structure until the exposed straight edge section is completely removed.

[0072] S10. Then remove the main body of the fixture, change the machining side, re-clamp it, and perform turning on the straight edge section 101 on the other side. Repeat the above operations S1-S9. After the turning is completed, remove the entire clamping structure.

[0073] Next, remove the precision-machined metal bellows assembly 100: assemble the entire clamping structure according to... Figure 3 Reinsert the device into the limiting structure 4 as shown, then loosen the pre-tightening screw 34, remove the entire expansion structure 3, then remove the three fastening screws 51, remove the clamping structure 2, and finally remove the precision-machined ultra-thin-walled metal bellows assembly 100 to obtain the desired result. Figure 8 The dimensions of the straight edge section shown can simultaneously ensure the coaxiality tolerance of the two straight edge sections 101, ensure that the surface of the bellows is free of indentations, that there are no chips on the inner and outer surfaces, that the dimensions of the straight edge sections are consistent, that the bellows has no residual deformation after processing, and that the effective length L remains unchanged.

[0074] It should be noted that the ultra-thin-walled metal bellows assembly 100 has several distinct characteristics: it is generally not single-layered, the single-layer wall thickness is less than 0.2mm, it is mostly a WW-joint welded structure, the structural dimensions of the bellows require high precision, the axial stiffness is low, the flexibility is high and it is easily deformed, the structural dimensions are small, and the surface is easily scratched during processing. This results in a very low yield and processing efficiency. In this embodiment, based on the above characteristics of the ultra-thin-walled metal bellows, the fixture is designed as a single-segment structure. The end face and straight edge section 101 of the metal bellows assembly 100 are used as contact surfaces for the fixture's limiting design. Simultaneously, utilizing the springback characteristics of the metal bellows assembly 100, the cavity closure dimension (Lx) during fixture mold closing is designed as follows: Figure 4 This ensures that when the metal bellows assembly 100 is fixed in the inner cavity of the fixture (i.e., the annular space), it is in an axially compressed state with a compression amount of x (the compression x here will not cause residual deformation to the bellows after processing). This guarantees that the two end faces of the metal bellows assembly 100 are completely fitted with the inner cavity of the fixture. Further design, such as... Figure 4The limiting dimension S−0.10 of the clamps on both sides and the straight edge section of the bellows is shown. By using two limiting pressure cones and expansion screws 34 to tighten the polyurethane expansion ring 31 of appropriate size and specific structure, and with the help of the designed limiting structure 4, the part of the polyurethane that deforms first can be accurately positioned at the straight edge section 101 of the inner cavity of the metal bellows assembly 100, thereby achieving tightening. In this way, the rotation of the metal bellows assembly 100 can be prevented during turning, and chips can be prevented from entering the inner cavity of the metal bellows assembly 100.

[0075] In this embodiment, the clamping structure designed by utilizing the springback characteristics of the metal bellows assembly 100 provides a novel method for installing and fixing the ultra-thin-walled metal bellows assembly 100. This method is particularly suitable for the precision dimensional machining of the straight edge section 101 of the ultra-thin-walled metal bellows assembly 100. Simultaneously, this design is also applicable to other bellows products with ultra-thin walls, small dimensions, low rigidity, high dimensional precision, high flexibility, and high requirements for internal and external surface quality. The clamping structure is simple and the processing cost is low, yet it effectively solves the clamping and fixing problem of ultra-thin-walled bellows, significantly improving the production efficiency and yield rate of ultra-thin-walled bellows.

[0076] It should be noted that S1 specifically includes the following steps:

[0077] S11. The support spindle 300 is engaged by the chuck 200 on the lathe, and the runout of the support spindle 300 is detected.

[0078] S12. Perform coaxiality testing on the straight edge sections 101 on both sides of the metal bellows assembly 100.

[0079] S13. After the coaxiality test in S12 is qualified, the rolling limit ring 400 is fitted into the outer wall of the straight edge section 101 on one side of the cantilever end, and the rolling limit ring 400 is pressed against the end wave ring surface of the metal bellows assembly 100.

[0080] S14. Next, the ultra-thin-walled metal bellows assembly 100 is fitted onto the cantilever end of the support mandrel 300 in S1. The metal bellows assembly 100 is moved so that the outer edge of the rolling limit ring 400 is aligned with the outer edge of the support mandrel 300 to form a cutting point.

[0081] S15. Then start the lathe and align the hobbing cutter 501 in the hobbing mechanism 500 on the lathe with the cutting point of the straight edge section 101 of the metal bellows assembly 100 to cut the exposed root. Feed the hobbing mechanism 500 radially along the metal bellows assembly 100 to cut off the hydraulically formed sealing length of the metal bellows assembly 100, leaving a machining allowance.

[0082] S16. The rough machining of the straight edge section 101 on the other side of the metal bellows assembly 100 can be completed by repeating the above rolling operation.

[0083] Here, the method for precision machining of the straight edge section 101 is as follows: First, rough machining is used to cut away the longer sealing straight edge section used for hydroforming, leaving a short straight edge section to be precision machined; the ultra-thin-walled metal bellows assembly 100 is clamped and fixed with a fixture for precision machining; next, turning is used for precision machining, the fixture is installed on a lathe and the exposed bellows straight edge section is turned; the fourth step is to take out the precision-machined metal bellows assembly 100.

[0084] It should also be noted that there are various models of the receiving body 1 and the pressing structure 2 in this embodiment. The operator can select the appropriate model of the receiving body 1 and the pressing structure 2 according to the size requirements of the metal bellows assembly 100 to adapt to the precision cutting of the straight edge section 101 of the metal bellows assembly 100 of different sizes.

[0085] In this embodiment, a jig for processing the straight edge section of an ultra-thin-walled metal bellows, namely a split-type jig, is used. The rough-machined metal bellows assembly 100 is placed in the second groove 12, and the clamping structure 2 is compressed along the axial direction of the metal bellows assembly 100 as a whole. The limiting inner hole of the clamping structure 2 and the receiving body 1 is made to fit with the outer diameter of the straight edge section 101 of the metal bellows assembly 100, and the contact length is the required processing size of the straight edge section 101. In this way, when the metal bellows assembly 100 is compressed, the circumferential plane of the two ends of the bellows is in close contact with the inner wall of the annular space, and the part of the straight edge section 101 that is exposed is the removal length. At the same time, the inner cavity of the metal bellows assembly 100 is expanded and tightened by the expansion structure 3, thereby realizing the clamping and fixing of the metal bellows assembly 100. Although the clamp of this invention consists of two halves, both halves are integral structures. The clamping principle is based on the springback characteristics of the metal bellows assembly 100, satisfying the need for clamping and fixing the processed straight-edge sections without leaving clamping marks on the inner and outer surfaces of the metal bellows assembly 100. Furthermore, it eliminates the need for a chip removal and absorption device, ensuring both processing efficiency and product qualification rate. This solves the technical problem of difficulty in clamping and fixing ultra-thin-walled bellows, which leads to difficulties in obtaining precise bellows dimensions. It also ensures the quality of the inner and outer surfaces of the metal bellows assembly 100 and the coaxiality of the two straight edges, significantly improving the production efficiency and product qualification rate of ultra-thin-walled bellows.

[0086] In addition, the fixture for machining the straight edge section of ultra-thin-walled metal bellows of the present invention, combined with a novel machining method, requires first rough machining of the metal bellows assembly 100, and then clamping the rough-machined metal bellows assembly 100 with the fixture to expose the part to be cut to the outside, and directly cutting it with a lathe tool 600, so as to ensure the machining accuracy of the straight edge section of the metal bellows assembly 100. It is suitable for the machining and manufacturing of ultra-thin-walled precision metal bellows with high surface quality requirements, small diameter, low rigidity, small effective length, small wave pitch, and unlimited number of layers, and is especially suitable for the precision machining of the straight edge section of ultra-thin-walled bellows.

[0087] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0088] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0089] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," or "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0090] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0091] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A fixture for machining the straight edge section of an ultra-thin-walled metal corrugated pipe, characterized in that: It includes a receiving body (1), a pressing structure (2), an expansion structure (3), and a limiting structure (4). The limiting structure (4) has a first groove (41) on one end face, and one end of the receiving body (1) can be embedded in the first groove (41). The receiving body (1) has a cylindrical through groove (11) on one end face, and a second groove (12) is formed radially outward at one end of the cylindrical through groove (11). A step is formed between the second groove (12) and the cylindrical through groove (11). The second groove (12) is used to place the metal bellows assembly (100). The metal bellows assembly (100) has two oppositely arranged straight edge sections (101). An annular receiving groove (42) is formed in the first groove (41) to accommodate one side of the straight edge section (101). The clamping structure (2) is fitted onto another straight edge section (101) of the metal bellows assembly (100), and the clamping structure (2) and the receiving body (1) are fixedly connected by fasteners (5) to form a clamping body for clamping the metal bellows assembly (100). The clamping structure (2) is used to block the second groove (12) and form an annular space between itself and the second groove (12) that can accommodate the metal bellows assembly (100). The two straight edge sections (101) extend outward along the axial direction to protrude from the clamping body. The expansion structure (3) extends into the fixture body to expand the two straight edge segments (101) of the metal bellows assembly (100) from the inside, respectively abutting against the axial end face one of the step and the axial end face two of the pressing structure (2). The expansion structure (3) passes through the fixture body and fixes the fixture body in the first groove (41) of the limiting structure (4). The receiving body (1), the pressing structure (2), the expansion structure (3) and the limiting structure (4) are coaxially arranged. The expansion structure (3) includes an expansion ring (31), a first limiting cone (32), a second limiting cone (33), and an expansion screw (34); the expansion ring (31) is located inside the metal bellows assembly (100), and the outer side wall of the expansion ring (31) abuts against the two straight edge segments (101) respectively. The expansion ring (31) has a central mounting hole (311). The first limiting cone (32) and the second limiting cone (33) are located on both sides of the central mounting hole (311). The first limiting cone (32) is partially inserted into one side of the central mounting hole (311), and the second limiting cone (33) is partially inserted into the other side of the central mounting hole (311). The first limiting cone (32) and the second limiting cone (33) are interlocked and locked by the expansion screw (34). The expansion ring (31) includes a cylindrical portion (312), and abutment ring portions (313) are integrally formed at both the upper and lower ends of the cylindrical portion (312) along its radial outward direction; the upper and lower ends of the central mounting hole (311) are both formed with inclined insertion ports (314), and the inclined portions of the first limiting cone (32) and the second limiting cone (33) abut against the inclined insertion ports (314); The first limiting cone (32) includes an integrally formed first frustum (321) and a first vertical cylinder (322), and the diameter of the first vertical cylinder (322) is equal to the diameter of the bottom end face of the first frustum (321). The first vertical cylinder (322) extends from one side of the expansion ring (31) into the central mounting hole (311) so that the inclined part of the first frustum (321) abuts against the inclined insertion port (314) at the upper end. A vertical hole (3211) is provided on the first frustum (321), and a slot (3221) is provided on the bottom end face of the first vertical cylinder (322), and the slot (3221) is connected to the vertical hole (3211). The expansion screw (34) passes through the vertical hole (3211) and the slot (3221) and forms a receiving space (35) between itself and the slot (3221). The second limiting cone (33) includes a second frustum (331) and a second vertical cylinder (332). The diameter of the second vertical cylinder (332) is smaller than the diameter of the top end face of the second frustum (331). The second vertical cylinder (332) extends from the other side of the expansion ring (31) into the central mounting hole (311) so that the inclined part of the second frustum (331) abuts against the inclined insertion port (314) at the lower end. The second vertical cylinder (332) is provided with a screw insertion hole (3321) so that the second vertical cylinder (332) forms an annular cylinder wall. The annular cylinder wall can be inserted into the receiving space (35). The bottom of the expansion screw (34) can be inserted and fixed in the screw insertion hole (3321). The bottom end face of the second frustum (331) extends downward along its axial direction to form a square limiting block (3311).

2. The fixture for machining the straight edge section of an ultra-thin-walled metal corrugated pipe as described in claim 1, characterized in that: The receiving body (1) is a disc-shaped structural component, and the receiving body (1) has a first end face (15) and a second end face (16) that are arranged opposite to each other. The first end face (15) is provided with a positioning groove (13) and a plurality of threaded holes (14) spaced apart along its circumference.

3. The fixture for machining the straight edge section of an ultra-thin-walled metal corrugated pipe as described in claim 2, characterized in that: The clamping structure (2) is a disc-shaped structure. A positioning block (21) is provided on one end face of the clamping structure (2) near the receiving body (1) along its axial direction. The positioning block (21) is engaged with the positioning groove (13). A through hole (22) is provided on the clamping structure (2) at the position corresponding to the threaded hole (14). The fastener (5) passes through the through hole (22) and is locked in the threaded hole (14). A central connecting hole (23) is provided at the center position of the clamping structure (2). The central connecting hole (23) is used to fit the other straight edge section (101) of the metal bellows assembly (100) and for the extension of the expansion structure (3).

4. The fixture for machining the straight edge section of an ultra-thin-walled metal corrugated pipe as described in claim 3, characterized in that: The expansion ring (31) is made of polyurethane.

5. The fixture for machining the straight edge section of an ultra-thin-walled metal corrugated pipe as described in claim 4, characterized in that: The limiting structure (4) is a disc-shaped structure. A square hole (43) communicating with the first groove (41) is provided at the center of the limiting structure (4). The square hole (43) is inserted into the square limiting block (3311).

6. The fixture for machining the straight edge section of an ultra-thin-walled metal corrugated pipe as described in claim 5, characterized in that: The fastener (5) includes a plurality of fastening screws (51) which are screwed into the threaded hole (14).

7. A processing method for the straight edge section of an ultra-thin-walled metal corrugated pipe, characterized in that: The method is based on the fixture for machining the straight edge section of an ultra-thin-walled metal bellows as described in any one of claims 1-6, and the method includes the following steps: S1. Cut the straight edge segments (101) on both sides of the metal bellows assembly (100) with a machining allowance to obtain the rough-machined metal bellows assembly (100). S2. Place the corrugated section of the rough-machined metal bellows assembly (100) in the cylindrical through groove (11) so that the straight edge section (101) on one side of the metal bellows assembly (100) protrudes outward relative to the receiving body (1). S3. The metal bellows assembly (100) in S2 is fitted into the clamping structure (2) so that the straight edge section (101) on the other side of the metal bellows assembly (100) protrudes outward relative to one side of the clamping structure (2); S4. The clamping structure (2) and the receiving body (1) are fixedly connected by fasteners (5) to form a clamping body for clamping the metal bellows assembly (100); S5. Use calipers to measure the thickness evenly along the circumferential edge of the fixture body, and the thickness measurements should be consistent. S6. Place the fixture body into the flat limiting structure (4); S7. The expansion structure (3) is passed through the inner cavity of the bellows and fixed to the limiting structure (4), and the expansion structure (3) is expanded radially along the metal bellows assembly (100) so that the expansion structure (3) abuts the straight edge sections (101) on both sides of the metal bellows assembly (100) against the fixture body respectively. S8. Remove the fixture body from the limiting structure (4) and place it on the chuck (200) of the lathe; S9. Control the cutting tool (600) to turn the straight edge section (101) of the metal bellows on the exposed side of the fixture body until the exposed straight edge section (101) is completely removed. S10. Then remove the main body of the fixture, change the machining side, re-clamp it, and perform turning of the straight edge section (101) on the other side. Repeat the above operations S1-S9.

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