Method for manufacturing a thin-walled casing

Abstract

The present application discloses a method for manufacturing a thin-walled casing. The present application provides a clamping portion for the wall thickness at one end of the thin-walled casing, which is used for clamping during the processing and cutting off after processing, thereby reducing the influence of the mandrel elastic force on the stress deformation of the inner hole surface of the workpiece, achieving the manufacturing and processing of casing parts with a large outer diameter-to-wall thickness ratio and a large aspect ratio, and can achieve precision processing of ultra-thin-walled casing parts, with high stability, batch manufacturing, stable dimensional accuracy and surface quality, and strong operability and application prospects. Moreover, an external support sleeve is further provided on the outside of the part blank processed into a thin-walled casing for clearance / interference / transition fit, which can effectively provide external support for the casing and improve processing accuracy.

Description

Technical Field

[0001] The present application relates to the technical field of manufacturing a control rod drive mechanism for nuclear power equipment, and in particular to a method for manufacturing a thin-walled casing. Background Art

[0002] In the prior art, the manufacturing of thin-walled sleeves is mainly done by forming the inner hole, supporting the inner hole with various mandrels, and then processing the outer cylindrical surface to the final part size. At the same time, if the seamless requirement is not considered, thin plate rolling and welding can be used; further, if the material restrictions are relaxed, rolling, casting and other methods can also be used for forming. It is extremely difficult to control the precision of thin walls.

[0003] However, for the processing of ultra-thin wall seamless pipes of martensitic stainless steel, the method of processing the outer circle after the inner hole is formed is a conventional method. However, due to the extremely large outer diameter to wall thickness ratio (more than 500), the design and precision control of the mandrel device are extremely critical. Since the inner hole is a positioning surface, the support of the inner circle after the mandrel is installed will affect the consistency of cutting. Therefore, the mandrel method needs to be carefully selected. The applicability of the spring mandrel is greatly reduced. In the 0-0.5mm wall thickness range, as the wall thickness decreases, the influence of the mandrel elastic force on the stress deformation of the workpiece will be multiplied. After the processing is completed, the spring mandrel unloading process will have a greater impact on the final size, and the size control is difficult. Moreover, the seamless pipe manufactured by the rolling method is difficult to control the size accuracy and has poor stability due to the ultra-low stiffness of the workpiece. Therefore, the existing ultra-thin wall seamless pipe processing methods cannot meet the requirements of size finishing and finished product stability, and there are difficulties in manufacturing shell parts with a large outer diameter to wall thickness ratio and a large aspect ratio. Summary of the invention

[0004] The purpose of the present application is to provide a method for manufacturing a thin-walled casing, so as to solve the problem that the existing ultra-thin-wall seamless tube processing methods cannot meet the requirements of dimensional accuracy and finished product stability, and to solve the manufacturing difficulties of casing-type ultra-thin-wall seamless tubes with extremely large outer diameter-to-wall thickness ratio and large aspect ratio.

[0005] In order to achieve the above-mentioned purpose, one embodiment of the present application provides a method for manufacturing a thin-walled casing, comprising the following steps:

[0006] A blank preparation step, using a rod or a tube as a part blank, wherein the end of the part blank is a clamping part, and the part between the two clamping parts is a product part;

[0007] A rough machining step of rough machining the part blank to form a rough machined outer cylindrical surface and a rough machined inner hole surface, and making a pressure relief groove between the clamping part and the product part;

[0008] a quenching and tempering heat treatment step, in which the part blank is heat treated;

[0009] A semi-finishing outer cylindrical surface step is performed, wherein the rough-machined outer cylindrical surface of the clamping portion is clamped on a supporting workpiece, and the rough-machined outer cylindrical surface of the product portion is semi-finished to form a semi-finished outer cylindrical surface;

[0010] A semi-finishing inner hole step, wherein the rough-machined inner hole surface of the product portion is semi-finished to form a semi-finished inner hole surface;

[0011] A finishing outer circle turning step, after the product portion is cooled, finishing the semi-finished outer circle surface of the product portion to form a finished outer circle surface;

[0012] an external support sleeve assembling step, assembling and fixing the external support sleeve on the finely machined outer circumferential surface of the product portion; and

[0013] The step of fine turning the inner hole is to use the outer cylindrical surface of the external support sleeve as the support surface, fix the two ends of the product part by clamping, and fine turn the semi-finished inner hole surface of the product part to form a finely finished inner hole surface, thereby obtaining a thin-walled sleeve shell.

[0014] In the method for manufacturing a thin-walled casing described in an embodiment of the present application, between the step of fine turning the outer circle and the step of assembling the outer support sleeve, there is also a step of cutting off the clamping portion, wherein the clamping portion is cut off at a position corresponding to the pressure relief groove.

[0015] In the method for manufacturing a thin-walled casing described in an embodiment of the present application, after the step of fine turning the inner hole, the method further includes: a step of splitting the outer support casing to separate the outer support casing from the product portion.

[0016] The method for manufacturing a thin-walled casing described in an embodiment of the present application further includes, after the step of fine turning the inner hole, a welding step of welding the outer support sleeve to the connecting positions of the two side ends of the product part.

[0017] In the method for manufacturing a thin-walled casing described in one embodiment of the present application, the external support casing is an electrical component body.

[0018] In the method for manufacturing a thin-walled casing described in one embodiment of the present application, in the blank preparation step, the material of the part blank includes martensitic stainless steel or austenitic stainless steel; in the rough machining step, it also includes making a pressure relief groove between the clamping part and the product part.

[0019] In the method for manufacturing a thin-walled casing described in one embodiment of the present application, in the step of assembling an external support sleeve, an inner side wall of the external support sleeve and a finely machined outer cylindrical surface of the product portion form an interference fit or a transition fit.

[0020] In the method for manufacturing a thin-walled casing described in one embodiment of the present application, in the step of assembling an external support sleeve, the external support sleeve is fixed to the finely machined outer circumferential surface of the product portion by means of an interference fit liquid nitrogen cold mounting method.

[0021] In the method for manufacturing a thin-walled shell described in one embodiment of the present application, in the step of assembling an external support sleeve, the external support sleeve uses a spring expansion sleeve as a base, and a first group of stress grooves and a second group of stress grooves are respectively arranged at the ends of the base in the axial direction, and the first group of stress grooves and the second group of stress grooves are arranged parallel to each other and staggered.

[0022] In the method for manufacturing a thin-walled sleeve described in one embodiment of the present application, in the step of assembling an external support sleeve, the external support sleeve includes two coupled semi-cylindrical shells, and the two semi-cylindrical shells are fastened together and fixed using a set of bolts and pins.

[0023] The beneficial effect of the present application is that a method for manufacturing a thin-walled casing is provided, by setting a clamping portion of the wall thickness at one end of the thin-walled casing, which is used for clamping during the processing and cutting off after processing, reducing the influence of the mandrel elastic force on the stress deformation of the inner hole surface of the workpiece, realizing the manufacturing and processing of casing parts with a large outer diameter wall thickness ratio and a large aspect ratio, being able to realize the precision processing of ultra-thin wall thickness casing parts, having high stability, being able to realize batch manufacturing, being able to provide stable dimensional accuracy and surface quality, having strong operability and application prospects. In addition, an external support sleeve is further set on the outside of the part blank processed into a thin-walled casing for clearance / interference / transition fit, so that there is a certain pre-tightening pressure between the casing and the external support sleeve, which can provide a large friction resistance, can effectively provide external support for the casing, and can improve the processing accuracy. At this time, the casing can not only be processed using the external support sleeve alone, but also can be assembled and processed in one piece with the electrical component body, that is, the electrical component body can be used as an external support sleeve, and at the same time, the assembly process is integrated, and the casing with a large outer diameter wall thickness ratio and a large aspect ratio can be precisely processed. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The technical solution and other beneficial effects of the present application are presented below in detail by describing the specific implementation methods of the present application in conjunction with the accompanying drawings.

[0025] Figure 1 A schematic diagram of the structure of a thin-walled casing provided in an embodiment of the present application.

[0026] Figure 2 for Figure 1 Schematic diagram of the cross-sectional structure at AA.

[0027] Figure 3 A flow chart of a method for manufacturing a thin-walled casing provided in an embodiment of the present application.

[0028] Figure 4 This is a structural schematic diagram of completing the rough machining step in the embodiment of the present application.

[0029] Figure 5 It is a structural schematic diagram of completing the semi-finishing inner hole turning step in the embodiment of the present application.

[0030] Figure 6 It is a structural schematic diagram of completing the step of cutting off the clamping part in the embodiment of the present application.

[0031] Figure 7 It is a schematic diagram of the combination of the external support sleeve and the thin-walled shell in the embodiment of the present application.

[0032] Figure 8 This is a schematic diagram of the morphology of the outer support sleeve and the thin-walled shell being combined and provided with a thickened layer in the embodiment of the present application.

[0033] Fig. 9 It is a schematic diagram of the cross-sectional structure of the first type of external support sleeve in the embodiments of the present application.

[0034] Fig.10 This is a schematic diagram of the front view structure of the first type of external support sleeve in the embodiments of the present application.

[0035] Fig.11 This is a schematic diagram of the front view structure of the second type of external support sleeve in the embodiment of the present application.

[0036] Fig.12 This is a schematic diagram of the front view structure of the third type of external support sleeve in the embodiment of the present application.

[0037] Fig.13 It is a structural schematic diagram of completing the step of fine turning the inner hole in the embodiment of the present application.

[0038] Fig.14 This is a structural schematic diagram of completing the step of disassembling the external support sleeve in an embodiment of the present application.

[0039] Fig.15 This is a schematic diagram of the structure in which the welding steps are completed in the embodiment of the present application. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0041] In the description of the present application, it should be understood that the terms "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0042] like Figure 1 , Figure 2 As shown, a thin-walled casing 10 (hereinafter referred to as casing) is provided in the embodiment of the present application. The thin-walled casing 10 includes a plurality of rotating body step nodes L1 and L2 distributed in the axial direction. The L1 segment is located at one end of the overall casing 10, and its wall thickness value t4 is slightly larger than or much larger than the wall thickness dimension t1 of the thin-walled segment at the right end. The L2 segment is located at the other end of the overall casing 10, and its wall thickness not only has all the characteristics of a thin wall, but also has a longer axial extension length. As the size limit of the wall thickness t1 further drops to the size range of 0.1-0.5mm, the difficulty of processing and size control of the L2 segment casing 10 increases exponentially.

[0043] In the manufacturing method of the thin-walled casing 10, the present application adds a process boss at the extension section L1 of the thin-walled L2 section to meet the requirements of clamping, increasing rigidity, etc., and removes the process boss in the final processing to complete the final processing. Therefore, the L1 section structure has a certain typicality and is retained here, but considering that its difficulty is much lower than that of the L2 section, the manufacturing method of the present application can be equally applicable. In summary, in order to characterize the high applicability of the manufacturing method of the present application, the L1 section is only used for illustration, and the present application focuses on the description of the wall thickness value of the L2 section. The process boss is also referred to as the clamping part in the following text.

[0044] like Figure 2 As shown, in the thin-walled casing 10, there is an inner hole surface N1 corresponding to the inner diameter dimension D1, and there is an outer cylindrical surface W1 corresponding to the outer diameter dimension D2, which is cylindrical in shape. The wall thickness of the casing 10 is the solid thickness between the outer cylindrical surface W1 and the inner hole surface N1, and the theoretical dimension is (D2-D1) / 2.

[0045] The wall thickness t1 value of the stainless steel thin-walled shell can be as thin as 0.1-0.5 mm, the diameter-to-wall thickness ratio exceeds 500, the aspect ratio exceeds 5, and high shape and position accuracy and dimensional accuracy are required in both radial and axial dimensions.

[0046] For details, please refer to Figure 3 As shown, a method for manufacturing a thin-walled casing 10 is provided in an embodiment of the present application, comprising the following steps S1-S9. Step S7 may be selectively present depending on the situation. Step S10 or step S11 may be included after step S9. The manufacturing method provided in the present application is also applicable to situations where the wall thickness is large. The relevant fixtures and cutting parameters are appropriately adjusted according to the actual manufacturing situation, and it has high applicability.

[0047] S1. Blank preparation steps. Use rods or tubes as part blanks. Please refer to Figure 4 As shown, the end of the part blank is a clamping part 11, and between the two clamping parts 11 is a product part 12. The clamping part 11 is clamped during the processing to support and drive the product part 12 to be processed, and the product part 12 is processed to form the stainless steel thin-walled shell. The material of the part blank includes martensitic stainless steel or austenitic stainless steel. The part blank is blanked with rods or tubes, and sufficient processing allowance is left at the outer circle and inner hole (if any) to meet the requirements of blank heat treatment, rough processing, semi-finishing and finishing. The clamping positions reserved at both ends are used as process bosses (i.e., clamping parts 11) for calibration, support, and support, and are also used as rough reference for processing. That is, in the blanking stage of the part blank, the axial length should have sufficient process allowance to avoid the product part 12 from being subjected to greater external pressure during subsequent processing.

[0048] S2, a rough machining step of forming a rough outer surface and a rough inner hole surface by rough machining the part blank, and making a pressure relief groove 13 between the clamping part 11 and the product part 12. Figure 4 The schematic diagram of the structure for completing the rough machining step. When rough machining the workpiece, the outer cylindrical surface W3 is machined to D9, and the inner hole surface N3 is machined to D8. The clamping position should be separated from the thin-walled section of the product part 12 by a sufficient pressure relief distance. Therefore, a pressure relief groove 13 is used to physically isolate the clamping part 11 and the product part 12 to minimize the pressure state of the casing 10 body. Rough machining is to remove most of the inner hole and outer cylindrical allowances, and at the same time, it should ensure that the casing 10 has a high rigidity.

[0049] S3, tempering heat treatment step, the part blank is subjected to dimension stabilization heat treatment. Through heat treatment, it is ensured that the mechanical properties of the part meet the requirements, the strength and toughness of the part material are improved, and the part has good comprehensive mechanical properties. At the same time, the internal stress of the part is greatly eliminated, and the shape is deformed to a stable size. Due to sufficient margin, the heat treatment deformation has little effect on the shape of the part. In subsequent processing, the accuracy can be ensured by re-aligning the part reference. Performance heat treatment can be appropriately adjusted according to material design requirements, but after rough processing, it must be combined with effective stress relief treatment to prevent bending deformation caused by stress concentration.

[0050] S4, semi-finishing outer circle step, clamping the rough-machined outer circle surface of the clamping part 11 to the supporting workpiece, and semi-finishing the rough-machined outer circle surface of the product part 12 after calibration to form a semi-finished outer circle surface. For details, please refer to Figure 5 As shown, the outer cylindrical positioning surfaces at both ends are polished, the supporting workpiece is clamped, and the shape is semi-finished after calibration. The outer cylindrical surface W4 is adjusted to size D10, leaving a finishing allowance, and the positioning surfaces W5 and W6 at both ends are repaired.

[0051] S5, a semi-finishing inner hole step, in which the rough-machined inner hole surface of the product portion 12 is semi-finished to form a semi-finished inner hole surface. Figure 5 The structural diagram of the semi-finishing inner hole turning step is shown. The outer circle W4 of the thin-walled section of the product part 12 and the datums C and D at both ends are recalibrated, and the inner hole area is turned to leave a finishing allowance, and the inner hole surface N4 size is processed to D7; a fixed width datum surface is set at the openings at both ends of the inner hole, and the position of the datum surface should be ensured to be within the range of the body (not at the process boss), and fine adjustments can be made according to actual conditions. The two datum inner hole surfaces are required to be cut by separate knives in one clamping to ensure coaxiality, that is, the datum A size of the openings at both ends is processed to D5, and the datum B size is processed to D6.

[0052] Furthermore, the method involved in the present application is that the final machining surface of the outer circle is formed before the final machining surface of the inner hole, that is, the outer circle needs to be machined to the final size D2 first, and then the inner hole is machined to the final size D1. Therefore, when cutting the outer circle of the shell, the size of the inner hole's margin will be directly reflected in the wall thickness value t2. A smaller inner hole margin t3 will cause a smaller wall thickness value t2 in the semi-finishing stage, further resulting in a significant reduction in rigidity and deformation of the shell 10. In order to ensure the precision of the outer circle machining, the inner hole here should retain a sufficient margin t3 to increase the rigidity of the shell, and its size value should simultaneously meet the requirements that the shell 10 should have sufficient rigidity during the outer circle machining and that the semi-finished shell 10 should have sufficiently small deformation after the outer circle machining is completed, thereby ensuring the manufacturing accuracy and assembly accuracy.

[0053] Furthermore, the allowance retained in the inner hole here cannot affect the accuracy of the final thin-wall processing. The reason is that if the size allowance t3 of the inner hole is too large, the final cutting amount will be too large, which will cause the processing stress and processing heat to affect the cutting process, making it difficult to control the deformation and affecting the processing accuracy.

[0054] In summary, through dual optimization of inner hole size and cutting parameters, the semi-finishing size of the inner hole is limited to the optimized value range, and the best one is selected through process tests and external dimension data.

[0055] S6, finishing outer circle step, after the product part 12 is sufficiently cooled, the semi-finished outer circle surface of the product part 12 is finished by finishing turning to form a finished outer circle surface after calibration. Figure 6 As shown, the clamping and supporting state of the semi-finishing turning process is maintained. After sufficient cooling, the datum AB is recalibrated, the outer cylindrical surface W1 is cut with separate knives, and the size is processed to the final D2 state.

[0056] S7, a step of cutting off the clamping part, cutting off the clamping part 11 at the position corresponding to the pressure relief groove 13. Cutting off the process bosses of the clamping part 11 at both ends as required, and forming all the other dimensional surfaces of the product part 12 except the inner hole. Figure 6 It is a structural schematic diagram for completing the step of cutting off the clamping part.

[0057] S8, assembling the external support sleeve step, assembling the external support sleeve 20 on the finely machined outer circumferential surface of the product part 12 and fixing it. The inner side wall of the external support sleeve 20 forms an interference fit or transition fit with the finely machined outer circumferential surface of the product part 12. The combination of the external support sleeve 20 and the thin-walled shell is as shown in the attached figure. Figure 7 As shown, the inner hole surface N2 of the external support sleeve 20 and the outer cylindrical surface W1 are in a matching relationship, and the matching form can be determined as clearance fit, interference fit, and transition fit according to the actual product requirements or the clamping requirements of the thin-walled shell 10. After matching, the locking device can be used to reasonably lock the external support sleeve 20 in the axial and circumferential directions. The outer circle contact state when the product part 12 and the external support sleeve 20 are assembled is defined as JX1 (clearance), GY1 (interference), GD1 (transition), and the contact state of the shell 10 with the external support sleeve 20 during processing is defined as JX2 (clearance), GY2 (interference), GD2 (transition). In the matching state of GY1 (interference), GD1 (transition), GY2 (interference), GD2 (transition), the product part 12 and the external support sleeve 20 have a certain pre-tightening pressure, which can provide a large friction resistance, can effectively provide external support for the product part 12, and can improve the processing accuracy.

[0058] Furthermore, when the thin-walled casing 10 is assembled with the external support casing 20, the inner hole of the part blank is in a state where a certain processing allowance is reserved to strengthen the rigidity of the casing, and a thickening layer 30 is provided in the inner hole of the part blank and is arranged corresponding to the external support casing 20. Figure 7 As shown, on the basis of the original design wall thickness t1, a thickening layer 30 with a thickness of t3 is added, which together constitutes a wall thickness t2 value, t1 corresponds to an inner diameter value D1, and t2 corresponds to an inner diameter value D7. Since the external support sleeve 20 and the thickening layer 30 are both used to fix the part blank to be processed, the external support sleeve 20 and the thickening layer 30 can be used as a clamping component to fix the product part 12. The part blank is clamped and fixed between the external support sleeve 20 and the thickening layer 30, and the inner hole is further fine-turned to form a thin-walled shell 10.

[0059] Furthermore, when the thin-walled casing 10 is assembled with the external support casing 20, the openings at both ends of the inner hole are also provided with a reference A and a reference B, and the corresponding reference apertures are D5 and D6. Generally, D5=D6, and its coaxial accuracy is ≤0.01, which serves as a precise reference for the processing, positioning, and correction of the thin-walled casing 10, and is a guarantee of the processing accuracy of the thin-walled casing 10.

[0060] Furthermore, in the JX1 (clearance) fitting state, there is a gap between the sleeve 10 and the inner hole of the component body, and the processing process may cause radial displacement of the sleeve 10. In this case, the sleeve 10 is no longer preferentially assembled with the electrical component body, but is instead processed separately, that is, it is transferred to the GY2 (interference) and GD2 (transition) fitting states.

[0061] Furthermore, in the JX2 (clearance) fit state, there is a gap between the sleeve 10 and the external support sleeve 20, and the processing process may cause radial displacement of the sleeve 10. In this case, the fit is adjusted to the GY2 (interference) and GD2 (transition) states.

[0062] Furthermore, the outer support sleeve 20 should be designed to ensure that its inner control surface N2 is in contact with the outer circumferential surface W1 of the sleeve shell 10 .

[0063] During the forming process of the thin-walled casing 10, due to its low rigidity characteristics of thin walls, the inner wall or outer wall of the casing 10 needs to be reinforced to limit its deformation. The external support sleeve 20 includes three structures, all of which can be fixed on the finely machined outer cylindrical surface of the product part 12 by means of interference fit liquid nitrogen cold mounting. Figure 8-11The external support sleeve 20 has an outer cylindrical surface W2, corresponding to the outer diameter D4, which can provide processing clamping and support, and the outer cylindrical surface is processed to a uniform size to ensure that both ends have high rigidity; the external support sleeve 20 has a base body, which has an inner hole surface N2, corresponding to the inner diameter D3, and the inner cavity is designed with corresponding axial limit according to the structure of the thin-walled shell 10. The inner diameter D3 is attached Figure 8-11 In the figure, the base is subdivided into D3-1, D3-2, and D3-3. After the base is assembled on the outer circumferential surface of the product part 12 of the part blank, a locking device is used to fix the product part 12 axially and circumferentially. The locking device is arranged around the axial and circumferential direction of the base, and the base is fixed by a locking nut or a pressure plate. The matching mode between the locking device and the base includes any one of clearance fit, interference fit, or transition fit.

[0064] like Figure 8 , Fig. 9 , Fig.10 As shown, the first type of external support sleeve 20 is the electrical component body, which is the base. The inner hole D3-1 of the electrical component body is used as the reference inner hole to control its manufacturing and assembly accuracy. The fit can be interference or transition state. After the product part 12 is manufactured, it can be installed at the inner hole of an electrical component body as the thin-walled sleeve 10 and welded with the body to achieve the sealing function. Therefore, the external support sleeve 20 is assembled on the outer side of the product part 12 for manufacturing. Not only can the processing of the thin-walled sleeve 10 be completed by forming alone, but also it can be assembled with the component body for processing according to needs, that is, the electrical component body can be used as the external support sleeve 20, which integrates the assembly process and has high flexibility.

[0065] like Fig.11 As shown, the second type of external support sleeve 20 adopts a spring expansion sleeve structure, with the spring expansion sleeve as the base, the inner hole size D3-2 is controlled, and the first group of stress grooves 21 and the second group of stress grooves 22 are respectively arranged at the ends of the base in the axial direction, and the first group of stress grooves 21 and the second group of stress grooves 22 are arranged parallel to each other. That is, two groups of staggered stress grooves are arranged at the wall thickness of the external support sleeve 20, and the rigid body is converted into an expansion sleeve with a certain elasticity. Combined with design calculation and stress analysis, the deformation of its elastic deformation is controlled, and the optimization design is performed, which can assist in the final processing of the thin-walled shell 10 and ensure the accuracy. The fit can be interference or transition state. When the external support sleeve 20 adopts a spring expansion sleeve structure, the locking device is a tightening ring or a semi-cylindrical pressure plate. The locking device is arranged around the base of the external support sleeve 20, so as to reduce the gap between the first group of stress grooves 21 and the second group of stress grooves 22 when being tightened, so as to realize that the external support sleeve 20 is fixed on the finely machined outer cylindrical surface of the product part 12.

[0066] like Fig.12 As shown, the third type of external support sleeve 20 adopts a split hoop form, and its inner hole size is D3-3, including two coupled semi-cylindrical shells 23 as a base, and the two semi-cylindrical shells 23 are fastened with a set of bolts and a pin 24. The external support sleeve 20 fastens the two coupled semi-cylindrical shells 23 with a set of bolts and a pin 24, and embraces the outer cylindrical surface W1 of the product part 12, and the fit can be interference or transition state.

[0067] The above three structures of the external support sleeve 20 can be flexibly used according to the contact state of the stainless steel sleeve 10, can effectively provide radial support for the outer surface of the sleeve 10, can significantly improve the rigidity of the sleeve 10 and maintain it until the sleeve 10 is completely processed.

[0068] S9, the step of fine turning the inner hole, using the outer cylindrical surface of the external support sleeve 20 as the support surface, fixing the two ends of the product part 12 by clamping, and after calibration, using a long-stroke anti-vibration tool rod split knife cutting method to fine turn the semi-finished inner hole surface of the product part 12 to form a finely finished inner hole surface, thereby obtaining a thin-walled shell 10.

[0069] like Fig.13 As shown, specifically, the outer cylindrical surface W2 of the external support sleeve 20 is used as the support surface, the left end G1 position is clamped, the center frame supports the right end G2, the two ends of the inner hole of the thin-walled shell 10 are calibrated, the coaxiality is Φ0.01, the machine tool is equipped with a long-stroke anti-vibration tool bar, and the inner hole is cut to size by separate knives. It can be understood that the outer cylindrical surface W2 can be clamped at the left end G1 position and the right end G2, and the center frame support method can be adopted. Fig.12 The schematic diagram is a structural diagram for completing the step of fine turning the inner hole.

[0070] Furthermore, in the semi-finishing process of the splitting knife process, uniform back cutting depth, feed speed, and normal coolant filling are adopted;

[0071] Furthermore, in the finishing process of the splitting knife process, a small back cutting amount and feed speed are adopted to maintain the rotation speed unchanged;

[0072] Furthermore, at the end of the finishing process of the knife division process, the back cutting amount is reduced to 0.02 mm, the cooling liquid filling is stopped, the inner hole is polished to the final size, and the thin-walled shell 10 is completely formed.

[0073] In this embodiment, step S10 or step S11 is further included after the inner hole finishing step S9.

[0074] S10, a step of separating the outer support sleeve, separating the outer support sleeve 20 from the product portion 12. Fig.14 The schematic diagram is a structural diagram for completing the steps of disassembling the outer support sleeve.

[0075] At this time, the disassembly of the outer support sleeve 20 is mainly divided into the following three situations according to the three structures of the outer support sleeve 20.

[0076] When the outer support sleeve 20 is an electrical component body, the thin-walled housing 10 is not disassembled after forming, that is, the processing and assembly of the thin-walled housing 10 are integrated, and the wall thickness value is verified by radial dimension difference method, cross-section method or distributed point wall thickness difference method.

[0077] Furthermore, the radial dimension difference method uses the difference between the inner hole size D3 of the external support sleeve 20 and the final manufacturing size D1 of the thin-walled sleeve 10 to calculate the wall thickness value of the thin-walled sleeve 10. This method is related to the workpiece matching state and machining calibration accuracy during the manufacturing process. On the one hand, under the matching state with a small interference fit, due to the ductility of the metal and the cutting force during the tool cutting process, the outer diameter D2 of the sleeve 10 and the inner hole D3 of the support sleeve will be formed along the large rigidity surface; on the other hand, the coaxial accuracy is controlled to less than 1 / 2 of the D1 tolerance range, which can effectively control the wall thickness accuracy.

[0078] Furthermore, the cross-sectional method is used to measure the wall thickness, that is, at the cross-sectional areas at both ends of the casing 10, the inner and outer circular contours on the cross-sectional areas of the casing 10 are projected and measured to calculate the wall thickness value, which is suitable for incomplete thickness detection of thin-walled casings that are not sealed at both ends.

[0079] Furthermore, the distributed point wall thickness difference method is calculated by measuring the wall thickness, that is, the full wall thickness of the external support sleeve 20 is calibrated at points, and the calibration value is Tn1. Then, the total wall thickness of the external support sleeve 20 and the thin-walled shell 10 after processing is calibrated, and the calibration value is Tn2. The wall thickness value t1 is the difference between Tn2 and Tn1.

[0080] When the external support sleeve 20 adopts a spring expansion sleeve structure, adjust the disassembly screw on the spring expansion sleeve, push the expansion sleeve open, and then insert a round nylon core shaft into the thin-walled sleeve 10 to prevent deformation. There is a stop at the end and the end face of the thin-walled sleeve 10, and the thin-walled sleeve 10 is pulled out of the inner cavity of the expansion sleeve through the nylon core shaft.

[0081] When the external support sleeve 20 adopts the split clamp form, the locking bolt group of the disassembly section of one half of the split clamp tool is loosened, and a round nylon core shaft is inserted into the thin-walled shell 10 to prevent deformation. There is a stop at the end and the end face of the thin-walled shell 10, and the thin-walled shell 10 is pulled out of the inner cavity of the split clamp through the nylon core shaft.

[0082] S11, a welding step, welding the connecting positions of the external support sleeve 20 and the two side ends of the product part 12. When the external support sleeve 20 is an electrical component body, after the product part 12 of the part blank is processed into a thin-walled sleeve 10, the two side ends of the electrical component body and the thin-walled sleeve 10 are welded and fixed to each other. Fig.15 This is a structural schematic diagram to complete the welding steps, in which the welding portion is represented by a black triangle.

[0083] The manufacturing method of the thin-walled shell 10 described in the present application can be used to process ultra-thin-wall seamless tubes for profiles made of martensitic stainless steel or austenitic stainless steel. The manufactured product has a very large outer diameter to wall thickness ratio (more than 500), and the wall thickness is less than or equal to 0.5 mm. The manufacturing problem of shell parts with a very large outer diameter to wall thickness ratio and a large aspect ratio is solved by cutting and forming.

[0084] The beneficial effect of the present application is that a method for manufacturing a thin-walled casing is provided, by setting a clamping portion of the wall thickness at one end of the thin-walled casing, which is used for clamping during the processing and cutting off after processing, reducing the influence of the mandrel elastic force on the stress deformation of the inner hole surface of the workpiece, realizing the manufacturing and processing of casing parts with a large outer diameter wall thickness ratio and a large aspect ratio, being able to realize the precision processing of ultra-thin wall thickness casing parts, having high stability, being able to realize batch manufacturing, being able to provide stable dimensional accuracy and surface quality, having strong operability and application prospects. In addition, an external support sleeve is further set on the outside of the part blank processed into a thin-walled casing for clearance / interference / transition fit, so that there is a certain pre-tightening pressure between the casing and the external support sleeve, which can provide a large friction resistance, can effectively provide external support for the casing, and can improve the processing accuracy. At this time, the casing can not only be processed using the external support sleeve alone, but also can be assembled and processed in one piece with the electrical component body, that is, the electrical component body can be used as an external support sleeve, and at the same time, the assembly process is integrated, and the casing with a large outer diameter wall thickness ratio and a large aspect ratio can be precisely processed.

[0085] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0086] The above is a detailed introduction to a method for manufacturing a thin-walled shell provided in an embodiment of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present application.

Claims

1. A method for manufacturing a thin-walled casing, characterized in that: The manufacturing method is applicable to a stainless steel thin-walled shell with a wall thickness ranging from 0.1 to 0.5 mm and a diameter-to-wall thickness ratio exceeding 500, and comprises the following steps: A blank preparation step, using a rod or a tube as a part blank, wherein the end of the part blank is a clamping part, and the product part is between two clamping parts; A rough machining step of rough machining the part blank to form a rough machined outer cylindrical surface and a rough machined inner hole surface, and making a pressure relief groove between the clamping part and the product part; a quenching and tempering heat treatment step, in which the part blank is heat treated; A semi-finishing outer cylindrical surface step is performed, wherein the rough-machined outer cylindrical surface of the clamping portion is clamped to support the workpiece, and the rough-machined outer cylindrical surface of the product portion is semi-finished to form a semi-finished outer cylindrical surface; A semi-finishing inner hole step, wherein the rough-machined inner hole surface of the product portion is semi-finished to form a semi-finished inner hole surface; A finishing outer circle turning step, after the product portion is cooled, finishing the semi-finished outer circle surface of the product portion to form a finished outer circle surface; a step of cutting off the clamping portion, cutting off the clamping portion at a position corresponding to the pressure relief groove; an external support sleeve assembling step, assembling and fixing the external support sleeve on the finely machined outer circumferential surface of the product portion; and The step of fine turning the inner hole is to use the outer cylindrical surface of the external support sleeve as the support surface, fix the two ends of the product part by clamping, and fine turn the semi-finished inner hole surface of the product part to form a finely finished inner hole surface, thereby obtaining a thin-walled sleeve shell.

2. The method for manufacturing a thin-walled casing according to claim 1, characterized in that: After the step of finishing the inner hole, the method further comprises: The step of separating the outer support sleeve is to separate the outer support sleeve from the product portion.

3. The method for manufacturing a thin-walled casing according to claim 1, characterized in that: After the step of finishing the inner hole, the method further comprises: The welding step is to weld the outer support sleeve to the connecting positions of the two side ends of the product part.

4. The method for manufacturing a thin-walled casing according to claim 3, characterized in that: The outer support sleeve is the electrical component body.

5. The method for manufacturing a thin-walled casing according to claim 1, characterized in that: In the blank preparation step, the material of the part blank includes martensitic stainless steel or austenitic stainless steel.

6. The method for manufacturing a thin-walled casing according to claim 1, characterized in that: In the step of assembling the external support sleeve, an inner side wall of the external support sleeve forms an interference fit or a transition fit with the finely machined outer circumferential surface of the product portion.

7. The method for manufacturing a thin-walled casing according to claim 1, characterized in that: In the step of assembling the external support sleeve, the external support sleeve is fixed on the finely machined outer circumferential surface of the product portion by means of interference fit liquid nitrogen cold mounting.

8. The method for manufacturing a thin-walled casing according to claim 1, characterized in that: In the step of assembling the external support sleeve, the external support sleeve uses a spring expansion sleeve as a base, and a first group of stress grooves and a second group of stress grooves are respectively arranged at the ends of the base in the axial direction, and the first group of stress grooves and the second group of stress grooves are arranged parallel to each other and staggered.

9. The method for manufacturing a thin-walled casing according to claim 1, characterized in that: In the step of assembling the external support sleeve, the external support sleeve includes two coupled semi-cylindrical shells, and the two semi-cylindrical shells are fastened together and fixed using a set of bolts and pins.

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