A large-length-diameter-ratio thin-wall cylinder composite spinning forming method

Abstract

The present application relates to a kind of large length-diameter ratio thin-walled cylinder composite spinning forming method, make full use of the advantage of the spinning forming of cylindrical part positive and spinning forming keeps higher forming precision and the characteristics of spinning forming getting rid of the axial dimension limit of equipment, using two pass positive spinning and one pass reverse spinning cooperation composite spinning forming method, realize the high quality, high efficiency, low cost production of large length-diameter ratio thin-walled cylinder.Design axial auxiliary limiting device can provide boundary condition compensation of reverse spinning forming, during reverse spinning forming process, formed part is not subjected to load, and is separated from the hard demand to spinning die, to realize the necessary conditions of large length-diameter ratio thin-walled cylinder composite spinning forming.Axial auxiliary limiting device includes annular positioning module and annular limiting module.The device can be in preset stroke stepless compensation axial spacing between quasi large length-diameter ratio cylinder and mould, without frequent installation and disassembly, and adjustment operation is simple.

Description

Technical Field

[0001] This invention relates to a composite spinning forming method for thin-walled cylindrical bodies with large aspect ratios, belonging to the field of high-strength spinning forming manufacturing of solid rocket engine combustion chamber shells. Background Technology

[0002] With the rapid development of technologies in the defense fields such as aviation and aerospace, the demand for thin-walled cylinders with large length-to-diameter ratios is increasing and becoming more urgent, such as a certain thin-walled cylinder product with a large length-to-diameter ratio. The material of the parts of this thin-walled cylinder product with a large length-to-diameter ratio is ultra-high strength steel 30Cr3, the length-to-diameter ratio of the cylinder structure is greater than 9, and the axial dimension exceeds 3000mm. This thin-walled cylinder with a large length-to-diameter ratio has processing challenges such as large length dimension, thin wall thickness, high forming difficulty, and high forming precision.

[0003] In existing forming technologies, the following forming methods are commonly used for thin-walled cylinders with large aspect ratios: 1. Large-size sheet metal is rolled and welded into thin-walled cylindrical parts with a large length-to-diameter ratio.

[0004] 2. Use positive spinning to form short-length thin-walled cylindrical parts, and then weld them together to form thin-walled cylindrical parts with a large length-to-diameter ratio; 3. Large horizontal or vertical spinning equipment is used for positive spinning to form thin-walled cylindrical parts with a large length-to-diameter ratio; 4. Thin-walled cylindrical parts with large length-to-diameter ratio are formed by multi-pass reverse spinning.

[0005] However, many problems exist, including: The following shortcomings exist when forming sheet metal by rolling and welding: the weld seam runs through the axial direction of the blank, and the welding accuracy and welding thermal stress pose a great challenge to ensuring the dimensional accuracy of the cylinder, such as straightness and roundness. The presence of axial weld seam will reduce the structural performance of the cylinder and pose a significant safety hazard.

[0006] The forming path of positive spinning combined with welding is applicable to most horizontal high-power spinning devices, and the positive spinning forming process can effectively ensure the geometric dimensions, form and position accuracy and performance requirements of small-sized thin-walled cylinders. However, due to the welding and splicing steps, the final products formed using this method still have accuracy deviations and performance risks. In addition, the extra steps generated when welding and spinning are combined, such as welding annealing, weld grinding, and weld non-destructive testing, increase the production cycle and economic cost of a single product.

[0007] When directly forming high-quality thin-walled cylindrical parts with a large aspect ratio through positive spinning, high requirements are placed on the spinning equipment and spinning mandrel. In particular, the equipment needs to have a larger power reserve, and the axial dimension of the spinning mandrel must meet the length requirements of the thin-walled cylindrical parts with a large aspect ratio. The manufacturing cost of the equipment and the mold is extremely high.

[0008] When reverse spinning thin-walled cylindrical parts with large length-to-diameter ratio, the dimensional accuracy of the finished product is greatly affected by the process characteristics of the load release of the formed blank during reverse spinning. This effect is especially pronounced for thin-walled cylindrical products, and the accumulated errors in the multi-pass forming process seriously affect the forming quality of the finished part. Summary of the Invention

[0009] The technical problem solved by this invention is to address the shortcomings of existing forming technologies for thin-walled cylinders with large aspect ratios, such as low forming quality, high equipment requirements, and high economic costs. This invention provides a composite spinning forming method for thin-walled cylinders with large aspect ratios, which uses two passes of forward spinning and one pass of reverse spinning, combined with an axial auxiliary limiting device, to achieve high-quality, high-efficiency, and low-cost production of thin-walled cylinders with large aspect ratios. The technical solution of this invention is: A composite spinning forming method for thin-walled cylindrical bodies with a large aspect ratio employs a composite spinning forming method combining two passes of forward spinning and one pass of reverse spinning, specifically including the following steps: Step 1: Prepare the spinning blank, which consists of two parts: the end section and the forming section blank. Step 2, fabricating the spinning mandrel 100: The spinning mandrel 100 is a hollow rotating body, including a forming section and an mounting section; the outer surface of the forming section is the working surface, the mandrel shoulder 300 of the mounting section is the mounting position of the axial auxiliary limiting device, the side of the mandrel shoulder 300 has three positioning keyways 302 and multiple threaded through holes 304, and the end face of the spinning mandrel 100 has multiple threaded holes 303 and a small taper structure 301; Step 3, install the spinning fixture, including the spinning mandrel 100, the axial auxiliary limiting device, and the spinning wheel; Install the spinning mandrel 100, and mate the threaded hole 303 at the mounting end of the spinning mandrel 100 with the spindle of the spinning equipment, using a double-ended bolt for connection; Install the axial auxiliary limiting device, put the axial auxiliary limiting device on the spinning core mold 100, and lock it in the positioning keyway 302 on the core mold shoulder 300 of the spinning core mold 100. Then, fix the annular positioning module 200 of the axial auxiliary limiting device with multiple countersunk screws 206. Install the spinning wheel, use the three-spinning wheel staggered spinning method, use the spinning wheel with a double conical surface structure, and the axis of the three spinning wheels is parallel to the spinning mandrel 100; Step 4: Install the spinning blank: Lubricant is applied to the outer surface of the forming section of the spinning mandrel 100, and the spinning blank is installed to ensure that the inner surface of the spinning blank fits well with the outer surface of the forming section of the spinning mandrel 100. Step 5: Set the parameters for the first pass of forward spinning; Step 6: First pass of forward spinning: Keeping the spinning gap between each spinning wheel and the spinning mandrel 100 constant, the first pass of positive spinning forming process is carried out according to the set first pass positive spinning parameters; cooling is performed during the spinning process; Step 7: Annealing treatment: Anneal the precast cylinder formed by the first pass of positive spinning. Step 8: Prepare for the second positive spinning process, including: cleaning the surface of the annealed cylinder, applying lubricant to the outer surface of the forming section of the spinning mandrel 100, and installing the annealed cylinder onto the spinning mandrel 100. Step 9: Set the parameters for the second pass of forward spinning; Step 10: Second pass forward spinning: Keep the spinning gap between each spinning wheel and the step shaft unchanged, and carry out the second pass forward spinning process according to the set second pass forward spinning parameters. Cooling is carried out during the spinning process. Step 11: Adjust the axial auxiliary limiting device so that the end face of the quasi-large length-to-diameter ratio cylinder 101 formed by the second pass of positive spinning fits well with the side surface 315 of the annular limiting module 202 of the axial auxiliary limiting device. Step 12: Set the anti-spin compression parameters; Step 13: Reverse spinning: Keep the spinning gap between each spinning wheel and the spinning mandrel 100 unchanged, and carry out the reverse spinning process according to the set reverse spinning parameters. Cooling is carried out during the spinning process. Step 14: Post-processing: After reverse spinning, the obtained thin-walled cylindrical part with a large aspect ratio is heat-treated, precision-machined, and coated to obtain the finished thin-walled cylindrical part with a large aspect ratio. Furthermore, step 1, preparing the spinning blank, specifically involves: The inner diameter of the blank in the closing section is 10-20mm smaller than the outer diameter of the mandrel, and the length of the blank in the forming section is... and wall thickness Must meet: (1) in , , These are the length, inner radius, and wall thickness of the target part, respectively. The percentage of the total thinning amount achieved by the first pass of positive spinning is given. The remaining length of the blank before the spinning wheel after the second pass of positive spinning forming; Furthermore, in step 2, when making the spinning mandrel (100), the length of the forming section is... Must meet: (2) in This is the length when the axial auxiliary limiting device is not in operation. This refers to the allowance length of the blank before the spinning wheel after the second pass of positive spinning. This is the maximum compensation dimension of the axial auxiliary limiting device. The length of the effective section of the quasi-large aspect ratio cylinder after the second forming process, satisfying: (3) in The percentage of wall thickness reduction during the second positive spinning process relative to the total wall thickness reduction.

[0010] Furthermore, the axial auxiliary limiting device mainly includes: annular positioning module 200, adjusting slider 201, annular limiting module 202, fine adjusting screw 203, adjusting nut 204, and coarse adjusting screw 205; The annular positioning module 200 has a key structure 305 on its axial end face, and a limit groove 306, an axial threaded through hole 307, and an axial countersunk through hole 308 on its axial middle side. The annular positioning module 200 is fixed to the spinning mandrel 100 by countersunk screws 206 passing through the axial countersunk through hole 308. The annular positioning module 200 has a radial countersunk through hole 309 on its axial inner surface and a scale line 310 on its outer surface. The adjusting slider 201 is set between the annular positioning module 200 and the annular limiting module 202. The top surface of the adjusting slider 201 has a through hole 312, and the side wall of the adjusting slider 201 is formed with an annular inclined surface A311. The adjusting slider 201 is locked in the limiting groove 306 of the annular positioning module 200, and is connected to the annular positioning module 200 by a thin adjusting screw 203 passing through the through hole 312. The thin adjusting screw 203 cooperates with the adjusting nut 204 to limit the movement distance of the adjusting slider 201. The annular limiting module 202 is fitted onto the annular positioning module 200. The side wall of the annular limiting module 202 is formed with an annular inclined surface B314, which is opposite to the annular inclined surface A311 of the adjusting slider 201. The axial side of the annular limiting module 202 has an axial through countersunk hole 313. The annular limiting module 202 is connected to the axial threaded through hole 307 of the annular positioning module 200 through a coarse adjusting screw 205. The side surface 315 of the annular limiting module 202 has a preset roughness requirement to provide a reverse spinning boundary condition for the quasi-large length-to-diameter ratio cylinder 101 to be limited. The fine adjusting screw 203 passes through the through hole 312 of the annular positioning module 200 and the adjusting slider 201, and is structurally connected to the adjusting nut 204 on the upper surface of the adjusting slider 201. The coarse adjusting screw 205 passes through the axial threaded through hole 307 of the annular positioning module 200 and the axial countersunk through hole 313 of the annular limiting module 202.

[0011] Furthermore, in step 11, the axial auxiliary limiting device is adjusted to ensure that the end face of the quasi-large aspect ratio cylinder 101, formed by the second pass of positive spinning, fits well with the side surface 315 of the annular limiting module 202. Specifically: Adjusting the coarse adjusting screw 205 opens the axial translational degree of freedom of the annular limiting module 202; rotating the adjusting nut 204 causes the adjusting slider 201 to perform radial translation under the constraint of the fine adjusting screw 203 and the limiting groove 306; the movement of the adjusting slider 201 is transmitted to the annular limiting module 202 through the annular inclined surface A311 and the annular inclined surface B314, causing the annular limiting module 202 to translate along the axial direction of the spinning mandrel 100; When the side surface 315 of the annular limiting module 202 comes into contact with the end face of the quasi-large length-to-diameter ratio cylinder 101, the coarse adjustment screw 205 is adjusted in the opposite direction to lock the axial translational degree of freedom of the annular limiting module 202, while ensuring that the end face of the quasi-large length-to-diameter ratio cylinder 101 fits well with the side surface 315 of the annular limiting module 202. The scale data at the time of fitting is recorded according to the scale line 310.

[0012] Furthermore, the parameter settings for the first pass of positive spinning in step 5 are as follows: the spindle speed of the spinning machine is 80~120 r / min, and the feed ratio is set to 0.8~1.2 mm / r; the thinning amount in the first pass of positive spinning is less than 50% of the total thinning amount in the forming process, wherein the thinning amount distribution ratio of the three spinning wheels is 2:1:1; when setting the spinning gap, factors such as the rigidity of the spinning machine and the springback of the blank need to be considered. During the first pass of positive spinning forming, the coolant flow rate is controlled at 200L / min.

[0013] Furthermore, in step 9, the parameters for the second pass of positive spinning are set as follows: the spindle speed of the spinning machine is 100~150 r / min, and the feed ratio is set to 1.0~1.5 mm / r; the thinning amount in the second pass of positive spinning process needs to make the blank axially elongate to the maximum safe position of the spinning wheel; when setting the spinning gap, the rigidity of the spinning machine and the springback of the blank need to be considered; the coolant flow rate is controlled at 200 L / min during the second pass of positive spinning forming.

[0014] Furthermore, in step 12, the reverse spinning parameters are set as follows: the spindle speed of the spinning machine is 80~120 r / min, and the feed ratio is set to 1.0~1.2 mm / r; when setting the forming thinning amount, it is ensured that the wall thickness of the cylindrical forging after forming reaches the required range, and the thinning amount accounts for 20%~30% of the total thinning amount. When setting the spinning gap, the rigidity of the spinning machine and the springback of the billet need to be considered.

[0015] Furthermore, after two rounds of positive rotation, the end face of the quasi-large length-to-diameter ratio cylinder is controlled within the allowable adjustment range of the axial auxiliary limiting device.

[0016] Furthermore, after the first pass of positive spinning forming, the inner diameter of the cylindrical blank is slightly expanded, which facilitates demolding and annealing; after the second pass of positive spinning forming, the cylindrical blank is reduced in diameter and adheres to the mold, improving forming accuracy.

[0017] The advantages of this invention compared to the prior art are: (1) The composite forming method in this invention utilizes the advantages of maintaining high forming accuracy in positive spinning forming of cylindrical parts and the characteristics of overcoming the axial dimension limitations of equipment in reverse spinning forming. It adopts a combination of two positive spinning passes and one reverse spinning pass to achieve high-quality, high-efficiency, and low-cost production of thin-walled cylindrical parts with large aspect ratios. The axial auxiliary limiting device provides the conditions for reverse spinning forming. During the reverse spinning forming process, since the formed part is not subjected to load, the structure of this part is freed from the rigid requirements of the spinning die, providing the necessary conditions for realizing the composite spinning forming of thin-walled cylindrical parts with large aspect ratios.

[0018] (2) The axial auxiliary limiting device of the present invention includes an annular positioning module. The annular positioning module is positioned and connected to the spinning mandrel through a positioning keyway and countersunk screw. A fine adjusting screw is mounted on the annular positioning module. An adjusting slider is located on the fine adjusting screw. The annular limiting module is placed on the side of the adjusting slider and is connected and fixed by a coarse adjusting screw. The forming conditions of the thin-walled cylinder with a large length-to-diameter ratio are provided by the coordinated movement of the adjusting slider and the annular limiting module. The device can steplessly compensate the axial distance between the quasi-large length-to-diameter ratio cylinder and the mold within a preset stroke. The adjustment operation is simple. It does not affect the normal operation of the equipment when not in use. It does not need to be disassembled and assembled frequently, which can significantly improve production efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the initial state of the first pass of positive spinning forming according to the present invention; Figure 2 This is a schematic diagram of the initial state of the second pass positive spinning forming of the present invention; Figure 3 This is a schematic diagram of the initial state of the reverse spinning forming of the present invention; Figure 4 This is a schematic diagram of the state after reverse spinning forming according to the present invention; Figure 5 This is a flowchart of the processing method of the present invention; Figure 6 This is a partially enlarged view of the axial auxiliary limiting device of the present invention; Figure 7 This is a partial structural view of the axial auxiliary limiting device of the present invention; Figure 8 This is an overall structural view of the axial auxiliary limiting device of the present invention; Figure 9 This is the spinning mandrel structure of the present invention (front view); Figure 10 This is a view of the spinning mandrel structure of the present invention. Figure 11 This is a schematic diagram of the annular positioning module structure of the axial auxiliary limiting device of the present invention; Figure 12 This is a schematic diagram of the adjusting slider structure of the axial auxiliary limiting device of the present invention; Figure 13 This is a schematic diagram of the annular limiting module structure of the axial auxiliary limiting device of the present invention. Detailed Implementation

[0020] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings.

[0021] like Figure 5 As shown, this invention provides a composite spinning forming method for thin-walled cylindrical bodies with a large aspect ratio, employing a composite spinning forming method combining two passes of forward spinning and one pass of reverse spinning, specifically including the following steps: Step 1: Prepare the spinning blank, which consists of two parts: the end section and the forming section blank. Step 2, as follows Figure 8 , Figure 9 As shown, the spinning mandrel 100 is fabricated as follows: The spinning mandrel 100 is a hollow rotating body, including a forming section and an mounting section; the outer surface of the forming section is the working surface, and the mandrel shoulder 300 of the mounting section is the mounting position for the axial auxiliary limiting device. The side of the mandrel shoulder 300 has three positioning keyways 302 and multiple threaded through holes 304. The end face of the spinning mandrel 100 has multiple threaded holes 303 and a small taper structure 301, as shown. Figure 10 As shown; Step 3, install the spinning fixture, including the spinning mandrel 100, the axial auxiliary limiting device, and the spinning wheel; Install the spinning mandrel 100, and mate the threaded hole 303 at the mounting end of the spinning mandrel 100 with the spindle of the spinning equipment, using a double-ended bolt for connection; Install the axial auxiliary limiting device, put the axial auxiliary limiting device on the spinning core mold 100, and lock it in the positioning keyway 302 on the core mold shoulder 300 of the spinning core mold 100. Then, fix the annular positioning module 200 of the axial auxiliary limiting device with multiple countersunk screws 206. Install the spinning wheel, use the three-spinning wheel staggered spinning method, use the spinning wheel with a double conical surface structure, and the axis of the three spinning wheels is parallel to the spinning mandrel 100; Step 4: Install the spinning blank: Lubricant is applied to the outer surface of the forming section of the spinning mandrel 100, and the spinning blank is installed to ensure that the inner surface of the spinning blank fits well with the outer surface of the forming section of the spinning mandrel 100. Step 5: Set the parameters for the first pass of forward spinning; Step 6: First pass of forward spinning: Maintaining the spinning gap between each spinning wheel and the spinning mandrel 100 unchanged, the first-pass positive spinning forming process is carried out according to the set first-pass positive spinning parameters; cooling is performed during the spinning process; the initial state diagram of the first-pass positive spinning forming is shown below. Figure 1 As shown.

[0022] Step 7: Annealing treatment: Anneal the precast cylinder formed by the first pass of positive spinning. Step 8: Prepare for the second positive spinning process, including: cleaning the surface of the annealed cylinder, applying lubricant to the outer surface of the forming section of the spinning mandrel 100, and installing the annealed cylinder onto the spinning mandrel 100. Step 9: Set the parameters for the second pass of forward spinning; Step 10: Second pass forward spinning: Keeping the spinning gap between each spinning wheel and the step shaft constant, perform the second pass forward spinning process according to the set second pass forward spinning parameters, and cool during the spinning process; the initial state diagram of the second pass forward spinning is shown below. Figure 2 As shown. Step 11: Adjust the axial auxiliary limiting device to ensure that the end face of the quasi-large aspect ratio cylinder 101, formed by the second pass of positive spinning, fits well with the side surface 315 of the annular limiting module 202 of the axial auxiliary limiting device. Figure 6 As shown; Step 12: Set the anti-spin compression parameters; Step 13: Reverse Spin Forming: Maintaining the spinning gap between each spinning wheel and the spinning mandrel 100 unchanged, perform the reverse spinning forming process according to the set reverse spinning parameters, and cool during the spinning process; the initial state diagram of reverse spinning forming is shown below. Figure 3 As shown in the diagram, the state after reverse spinning is as follows: Figure 4 As shown.

[0023] Step 14: Post-processing: After reverse spinning, the obtained thin-walled cylindrical part with a large aspect ratio is heat-treated, precision-machined, and coated to obtain the finished thin-walled cylindrical part with a large aspect ratio. Furthermore, step 1, preparing the spinning blank, specifically involves: The inner diameter of the blank in the closing section is 10-20mm smaller than the outer diameter of the mandrel, and the length of the blank in the forming section is... and wall thickness Must meet: (1) in , , These are the length, inner radius, and wall thickness of the target part, respectively. The percentage of the total thinning amount achieved by the first pass of positive spinning is given. The remaining length of the blank before the spinning wheel after the second pass of positive spinning forming; Furthermore, in step 2, when making the spinning mandrel (100), the length of the forming section is... Must meet: (2) in This is the length when the axial auxiliary limiting device is not in operation. This refers to the allowance length of the blank before the spinning wheel after the second pass of positive spinning. This is the maximum compensation dimension of the axial auxiliary limiting device. The length of the effective section of the quasi-large aspect ratio cylinder after the second forming process, satisfying: (3) in The percentage of wall thickness reduction during the second positive spinning process relative to the total wall thickness reduction.

[0024] like Figure 6 and Figure 7 As shown, the axial auxiliary limiting device mainly includes: annular positioning module 200, adjusting slider 201, annular limiting module 202, fine adjusting screw 203, adjusting nut 204, and coarse adjusting screw 205; like Figure 11 As shown, the annular positioning module 200 has a key structure 305 on its axial end face, and a limit groove 306, an axial threaded through hole 307, and an axial countersunk through hole 308 on its axial middle side. The annular positioning module 200 is fixed to the spinning mandrel 100 by countersunk screws 206 passing through the axial countersunk through hole 308. The annular positioning module 200 has a radial countersunk through hole 309 on its axial inner surface and a scale line 310 on its outer surface. like Figure 12 As shown, the adjusting slider 201 is disposed between the annular positioning module 200 and the annular limiting module 202. The top surface of the adjusting slider 201 has a through hole 312, and the side wall of the adjusting slider 201 is formed with an annular inclined surface A311. The adjusting slider 201 is locked in the limiting groove 306 of the annular positioning module 200, and is connected to the annular positioning module 200 by a thin adjusting screw 203 passing through the through hole 312. The thin adjusting screw 203 cooperates with the adjusting nut 204 to limit the movement distance of the adjusting slider 201. The annular limiting module 202 is fitted onto the annular positioning module 200. The side wall of the annular limiting module 202 has an annular inclined surface B314, which is opposite to the annular inclined surface A311 of the adjusting slider 201. An axial through countersunk hole 313 is opened on the axial side of the annular limiting module 202. The annular limiting module 202 is connected to the axial threaded through hole 307 of the annular positioning module 200 via a coarse adjusting screw 205. The side surface 315 of the annular limiting module 202 has a preset roughness requirement, providing a reverse-spinning boundary condition for the large aspect ratio cylinder 101 to be limited. Figure 13 As shown; The fine adjusting screw 203 passes through the through hole 312 of the annular positioning module 200 and the adjusting slider 201, and is structurally connected to the adjusting nut 204 on the upper surface of the adjusting slider 201. The coarse adjusting screw 205 passes through the axial threaded through hole 307 of the annular positioning module 200 and the axial countersunk through hole 313 of the annular limiting module 202.

[0025] Furthermore, in step 11, the axial auxiliary limiting device is adjusted to ensure that the end face of the quasi-large aspect ratio cylinder 101, formed by the second pass of positive spinning, fits well with the side surface 315 of the annular limiting module 202. Specifically: Adjusting the coarse adjusting screw 205 opens the axial translational degree of freedom of the annular limiting module 202; rotating the adjusting nut 204 causes the adjusting slider 201 to perform radial translation under the constraint of the fine adjusting screw 203 and the limiting groove 306; the movement of the adjusting slider 201 is transmitted to the annular limiting module 202 through the annular inclined surface A311 and the annular inclined surface B314, causing the annular limiting module 202 to translate along the axial direction of the spinning mandrel 100; When the side surface 315 of the annular limiting module 202 comes into contact with the end face of the quasi-large length-to-diameter ratio cylinder 101, the coarse adjustment screw 205 is adjusted in the opposite direction to lock the axial translational degree of freedom of the annular limiting module 202, while ensuring that the end face of the quasi-large length-to-diameter ratio cylinder 101 fits well with the side surface 315 of the annular limiting module 202. The scale data at the time of fitting is recorded according to the scale line 310.

[0026] Furthermore, the parameter settings for the first pass of positive spinning in step 5 are as follows: the spindle speed of the spinning machine is 80~120 r / min, and the feed ratio is set to 0.8~1.2 mm / r; the thinning amount in the first pass of positive spinning is less than 50% of the total thinning amount in the forming process, wherein the thinning amount distribution ratio of the three spinning wheels is 2:1:1; when setting the spinning gap, factors such as the rigidity of the spinning machine and the springback of the blank need to be considered. During the first pass of positive spinning forming, the coolant flow rate is controlled at 200L / min.

[0027] Furthermore, in step 9, the parameters for the second pass of positive spinning are set as follows: the spindle speed of the spinning machine is 100~150 r / min, and the feed ratio is set to 1.0~1.5 mm / r; the thinning amount in the second pass of positive spinning process needs to make the blank axially elongate to the maximum safe position of the spinning wheel; when setting the spinning gap, the rigidity of the spinning machine and the springback of the blank need to be considered; the coolant flow rate is controlled at 200 L / min during the second pass of positive spinning forming.

[0028] Furthermore, in step 12, the reverse spinning parameters are set as follows: the spindle speed of the spinning machine is 80~120 r / min, and the feed ratio is set to 1.0~1.2 mm / r; when setting the forming thinning amount, it is ensured that the wall thickness of the cylindrical forging after forming reaches the required range, and the thinning amount accounts for 20%~30% of the total thinning amount. When setting the spinning gap, the rigidity of the spinning machine and the springback of the billet need to be considered.

[0029] Furthermore, after two rounds of positive rotation, the end face of the quasi-large length-to-diameter ratio cylinder is controlled within the allowable adjustment range of the axial auxiliary limiting device.

[0030] Furthermore, after the first pass of positive spinning forming, the inner diameter of the cylindrical blank is slightly expanded, which facilitates demolding and annealing; after the second pass of positive spinning forming, the cylindrical blank is reduced in diameter and adheres to the mold, improving forming accuracy.

[0031] Example: Example 1: Reference Figures 1-13 This paper describes a composite spinning forming method for 30Cr3 thin-walled cylinders with a large aspect ratio and the method for using its axial auxiliary limiting device. The target inner diameter of the thin-walled cylinder product is 300mm, the length is 3000mm, and the wall thickness is 2mm.

[0032] Step 1, Design and preparation of the spinning blank: The billet has an inner diameter of 300mm, an inner diameter of 280mm for the closing section, and a wall thickness of 12mm. According to Formula 1, the total length of the billet can be taken as 520mm.

[0033] Step 2, make spinning mandrel 100: The spinning mandrel 100 is a hollow rotating body, including a forming section and an installation section; the outer surface of the forming section is the working surface, and the positioning keyway 302 on the mandrel shaft shoulder 300 of the installation section is the installation position of the axial auxiliary limiting device. According to formulas 2 and 3, the length of the forming section can be designed to be 1620mm and the outer surface diameter is 299.5mm.

[0034] Step 3, Install the spinning fixture: The installation of the spinning fixture includes installing the spinning mandrel 100, the axial auxiliary limiting device, and the spinning wheel; Install the spinning mandrel 100, and install the tapered structure 301 at the mounting end of the spinning mandrel 100 with the spindle of the spinning equipment using double-ended bolts; Install the axial auxiliary limiting device, put the axial auxiliary limiting device on the spinning core mold 100, fix the key structure 305 on the annular positioning module 200 of the axial auxiliary limiting device to the positioning keyway 302 on the core mold shoulder 300 of the spinning core mold 100, and fix the annular positioning module 200 of the axial auxiliary limiting device by six countersunk screws 206. Install spinning wheels and use a staggered spinning forming method with three spinning wheels evenly distributed circumferentially.

[0035] Step 4: Install the spinning blank: Lubricant is applied to the outer surface of the forming section of the spinning mandrel 100, and the spinning blank cylinder is installed to ensure that the inner surface of the spinning blank is well attached to the surface of the forming section of the spinning mandrel 100.

[0036] Step 5: Setting parameters for the first pass of forward spinning: The spindle speed of the spinning machine is 80 r / min, and the feed ratio is 0.8 mm / r. The thinning amount of the first pass of positive spinning is 4 mm, of which the thinning amounts of the three spinning wheels are distributed as 2.0, 1.0 and 1.0 mm respectively. When setting the spinning gap, a 1 mm downward pressure compensation is added to the pressing amount. Step 6: First pass of forward spinning: Keep the spinning gap between each spinning wheel and the spinning mandrel 100 unchanged, and carry out the first pass of positive spinning forming according to the set parameters; cooling is carried out during the spinning process, and the coolant flow rate is controlled at 200L / min; Step 7: Annealing treatment: The precast cylinder formed by the first pass of positive spinning is annealed: held at 750℃ for 3 hours, air-cooled to 690℃ and held for 5 hours, cooled in the furnace to 500℃ and then air-cooled. After annealing, the billet is restored to or close to the plastic conditions before spinning. Step 8: Prepare for the second pass of positive spinning. The installation steps include: cleaning the surface of the annealing cylinder, applying lubricant, and installing the annealing cylinder onto the spinning mandrel 100.

[0037] Step 9: Setting parameters for the second pass of forward spinning: The spindle speed of the spinning machine is 150 r / min, and the feed ratio is 1.5 mm / r; the thinning amount of the second pass of the positive spinning process is 4 mm, and the thinning amount distribution ratio of the three spinning wheels in this pass is 1.8, 1.2, and 1.0 respectively; when setting the spinning gap, a 1 mm downward pressure compensation is added. Step 10: Second pass of forward spinning: Keep the spinning gap between each spinning wheel and the spinning mandrel 100 unchanged, and carry out the second positive spinning forming process according to the set parameters; cooling is carried out during the spinning process, and the coolant flow rate is controlled at 200L / min; Step 11: Adjust the axial auxiliary limiting device: Adjust the coarse adjusting screw 205 to open the axial translational freedom of the annular limiting module 202, allowing it to move freely along the axial direction of the spinning mandrel 100; rotate the adjusting nut 204, and the adjusting slider 201, constrained by the fine adjusting screw 203 and the limiting groove 306, moves radially along the spinning mandrel 100; the movement of the adjusting slider 201 is transmitted to the annular limiting module 202 through the annular inclined surfaces A311 and B314, causing the annular limiting module 202 to move along the axial direction of the spinning mandrel 100; when the side surface 315 of the annular limiting module 202 contacts the end face of the quasi-large length-to-diameter ratio cylinder 101, adjust the coarse adjusting screw 205 in the opposite direction to lock the axial translational freedom of the annular limiting module 202, so that the end face of the quasi-large length-to-diameter ratio cylinder 101 fits well with the side surface 315 of the annular limiting module 202, and record the scale data at the time of fitting according to the scale line 310.

[0038] Step 12: Setting the anti-spinning parameters: The spindle speed of the spinning machine is 100 r / min, and the feed ratio is 1.0 mm / r; the thinning amount of the reverse spinning forming is 2 mm, of which the thinning amount distribution ratio of the three spinning wheels is approximately 1, 0.5, and 0.5 mm; when setting the spinning gap, an additional 1 mm of downward pressure compensation is added. Step 13: Reverse spinning: Keep the spinning gap between each spinning wheel and the spinning mandrel 100 constant, and carry out the reverse spinning forming process according to the set parameters; cooling is carried out during the spinning process, and the coolant flow rate is controlled at 200L / min; Step 14: Follow-up processing: The obtained thin-walled cylindrical spinning parts with large length-to-diameter ratio are subjected to heat treatment, precision machining, coating and other subsequent treatments to obtain thin-walled cylindrical products with large length-to-diameter ratio.

[0039] The parts of this invention not described in detail are common knowledge to those skilled in the art.

Claims

1. A method for composite spinning forming of thin-walled cylindrical bodies with a large aspect ratio, characterized in that, The composite spinning process, which combines two forward spinning passes with one reverse spinning pass, specifically includes the following steps: Step 1: Prepare the spinning blank, which consists of two parts: the end section and the forming section blank. Step 2, making the spinning mandrel (100): The spinning mandrel (100) is a hollow rotating body, including a forming section and an installation section; the outer surface of the forming section is the working surface, the mandrel shoulder (300) of the installation section is the installation position of the axial auxiliary limiting device, the side of the mandrel shoulder (300) has three positioning keyways (302) and multiple threaded through holes (304), and the end face of the spinning mandrel (100) has multiple threaded holes (303) and a small taper structure (301); Step 3, install the spinning fixture, including the spinning mandrel (100), axial auxiliary limiting device, and spinning wheel; Install the spinning die (100), and mate the threaded hole (303) at the mounting end of the spinning die (100) with the spindle of the spinning equipment, using double-ended bolts for connection; Install the axial auxiliary limiting device, put the axial auxiliary limiting device on the spinning core mold (100), and lock it in the positioning keyway (302) on the core mold shaft shoulder (300) of the spinning core mold (100). Then fix the annular positioning module (200) of the axial auxiliary limiting device with multiple countersunk screws (206). Install the spinning wheel, use the three-spinning wheel staggered spinning method, use the spinning wheel with a double conical surface structure, and the axis of the three spinning wheels is parallel to the axis of the spinning mandrel (100); Step 4: Install the spinning blank: Lubricant is brushed onto the outer surface of the forming section of the spinning mandrel (100), and the spinning blank is installed to ensure that the inner surface of the spinning blank fits well with the outer surface of the forming section of the spinning mandrel (100). Step 5: Set the parameters for the first pass of forward spinning; Step 6: First pass of forward spinning: Keep the spinning gap between each spinning wheel and the spinning mandrel (100) unchanged, and carry out the first-pass positive spinning forming process according to the set first-pass positive spinning parameters; cooling is carried out during the spinning process; Step 7: Annealing treatment: Anneal the precast cylinder formed by the first pass of positive spinning. Step 8: Prepare for the second positive spinning process, including: cleaning the surface of the annealed cylinder, applying lubricant to the outer surface of the forming section of the spinning mandrel (100), and installing the annealed cylinder onto the spinning mandrel (100); Step 9: Set the parameters for the second pass of forward spinning; Step 10: Second pass forward spinning: Perform the second pass forward spinning process according to the set parameters, and cool during the spinning process; Step 11: Adjust the axial auxiliary limiting device so that the end face of the quasi-large length-to-diameter ratio cylinder (101) formed by the second pass of positive spinning fits well with the side surface (315) of the annular limiting module (202) of the axial auxiliary limiting device. Step 12: Set the anti-spin compression parameters; Step 13: Reverse spinning: Keep the spinning gap between each spinning wheel and the spinning mandrel (100) unchanged, and carry out the reverse spinning process according to the set reverse spinning parameters. Cooling is carried out during the spinning process. Step 14: Post-processing: After reverse spinning, the obtained thin-walled cylindrical part with a large aspect ratio is heat-treated, precision-machined, and coated to obtain the finished thin-walled cylindrical part with a large aspect ratio. The axial auxiliary limiting device includes: annular positioning module (200), adjusting slider (201), annular limiting module (202), fine adjusting screw (203), adjusting nut (204), and coarse adjusting screw (205); The annular positioning module (200) has a key structure (305) on its axial end face, and a limit groove (306), an axial threaded through hole (307), and an axial countersunk through hole (308) on its axial middle side. The annular positioning module (200) is fixed on the spinning mandrel (100) by countersunk screws (206) passing through the axial countersunk through hole (308). The annular positioning module (200) has a radial countersunk through hole (309) on its axial inner surface and a scale line (310) on its outer surface. The adjusting slider (201) is set between the annular positioning module (200) and the annular limiting module (202). The top surface of the adjusting slider (201) has a through hole (312), and the side wall of the adjusting slider (201) is formed with an annular inclined surface A (311). The adjusting slider (201) is locked on the limiting groove (306) of the annular positioning module (200), and is connected to the annular positioning module (200) by passing through the through hole (312) with a thin adjusting screw (203). The thin adjusting screw (203) cooperates with the adjusting nut (204) to limit the movement distance of the adjusting slider (201). The annular limiting module (202) is fitted onto the annular positioning module (200). The side wall of the annular limiting module (202) is formed with an annular inclined surface B (314), which is opposite to the annular inclined surface A (311) of the adjusting slider (201). The annular limiting module (202) has an axial through countersunk hole (313) on its axial side. The annular limiting module (202) is connected to the axial threaded through hole (307) of the annular positioning module (200) through a coarse adjusting screw (205). The side surface (315) of the annular limiting module (202) has a preset roughness requirement to provide anti-spinning boundary conditions for the quasi-large length-to-diameter ratio cylinder (101) to be limited. The fine adjusting screw (203) passes through the through hole (312) of the annular positioning module (200) and the adjusting slider (201), and is structurally connected to the adjusting nut (204) on the upper surface of the adjusting slider (201); The coarse adjusting screw (205) passes through the axial threaded through hole (307) of the annular positioning module (200) and the axial countersunk through hole (313) of the annular limiting module (202).

2. The method for composite spinning of thin-walled cylindrical bodies with large aspect ratio according to claim 1, characterized in that: Step 1, preparing the spinning blank, specifically involves: The inner diameter of the blank in the closing section is 10-20mm smaller than the outer diameter of the spinning mandrel, and the length of the blank in the forming section is... and wall thickness Must meet: (1) in , , These are the length, inner radius, and wall thickness of the target part, respectively. The percentage of the total thinning amount achieved by the first pass of positive spinning is given. This refers to the remaining length of the blank before the spinning wheel after the second pass of positive spinning forming.

3. The method for composite spinning of thin-walled cylindrical bodies with large aspect ratio according to claim 2, characterized in that: When making the spinning mandrel (100) in step 2, the length of the forming section Must meet: (2) in This is the length when the axial auxiliary limiting device is not in operation. This refers to the allowance length of the blank before the spinning wheel after the second pass of positive spinning. This is the maximum compensation dimension of the axial auxiliary limiting device. The length of the effective section of the quasi-large aspect ratio cylinder after the second forming process, satisfying: (3) in The percentage of wall thickness reduction during the second positive spinning process relative to the total wall thickness reduction.

4. The method for composite spinning of thin-walled cylindrical bodies with large aspect ratio according to claim 1, characterized in that: Step 11: Adjust the axial auxiliary limiting device to ensure good fit between the end face of the quasi-large aspect ratio cylinder (101) formed by the second pass of positive spinning and the side surface (315) of the annular limiting module (202). Specifically: Adjusting the coarse adjusting screw (205) opens the axial translational freedom of the annular limiting module (202); rotating the adjusting nut (204), the adjusting slider (201) is constrained by the fine adjusting screw (203) and the limiting groove (306) to perform radial translation; the movement of the adjusting slider (201) is transmitted to the annular limiting module (202) through the annular inclined surface A (311) and the annular inclined surface B (314), causing the annular limiting module (202) to translate along the axial direction of the spinning mandrel (100); When the side surface (315) of the annular limiting module (202) comes into contact with the end face of the quasi-large length-to-diameter ratio cylinder (101), the coarse adjustment screw (205) is adjusted in the opposite direction to lock the axial translational degree of freedom of the annular limiting module (202), while ensuring that the end face of the quasi-large length-to-diameter ratio cylinder (101) fits well with the side surface (315) of the annular limiting module (202), and the scale data at the time of fitting is recorded according to the scale line (310).

5. The method for composite spinning of thin-walled cylindrical bodies with large aspect ratio according to claim 1, characterized in that: The parameters for the first pass of positive spinning in step 5 are as follows: the spindle speed of the spinning machine is 80~120 r / min, and the feed ratio is set to 0.8~1.2 mm / r; the thinning amount in the first pass of positive spinning is less than 50% of the total thinning amount in the forming process, and the thinning amount distribution ratio of the three spinning wheels is 2:1:1; when setting the spinning gap, the rigidity of the spinning machine and the springback of the blank should be considered. During the first pass of positive spinning forming, the coolant flow rate is controlled at 200L / min.

6. The method for composite spinning of thin-walled cylindrical bodies with large aspect ratio according to claim 1, characterized in that: Step 9 sets the parameters for the second pass of positive spinning, specifically: the spindle speed of the spinning machine is 100~150 r / min, and the feed ratio is set to 1.0~1.5 mm / r; the thinning amount in the second pass of positive spinning process needs to make the blank axially elongate to the maximum safe position of the spinning wheel; when setting the spinning gap, the rigidity of the spinning machine and the springback of the blank need to be considered; the coolant flow rate is controlled at 200 L / min during the second pass of positive spinning forming.

7. The method for composite spinning of thin-walled cylindrical bodies with large aspect ratio according to claim 1, characterized in that: Step 12 sets the reverse spinning parameters, specifically: the spindle speed of the spinning machine is 80~120 r / min, and the feed ratio is set to 1.0~1.2 mm / r; when setting the forming thinning amount, ensure that the wall thickness of the cylindrical forging after forming reaches the required range, and the thinning amount accounts for 20%~30% of the total thinning amount. When setting the spinning gap, the rigidity of the spinning machine and the springback of the billet need to be considered.

8. The method for composite spinning of thin-walled cylindrical bodies with large aspect ratio according to claim 1, characterized in that: After two rounds of positive rotation, the end face of the quasi-large length-to-diameter ratio cylinder is controlled within the allowable adjustment range of the axial auxiliary limiting device.

9. The method for composite spinning of thin-walled cylindrical bodies with large aspect ratio according to claim 1, characterized in that: After the first pass of positive spinning forming, the inner diameter of the cylindrical blank is slightly expanded, which facilitates demolding and annealing; after the second pass of positive spinning forming, the diameter of the cylindrical blank is reduced and it fits the mold, which improves the forming accuracy.

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