Design method for integrally-formed thin-walled cylindrical part spinning blank with conical section connector

Abstract

The invention relates to a design method for integrally forming a spinning blank of a thin-wall cylindrical part with a conical section joint, which aims at integrally spinning and forming a complex thin-wall cylindrical part with the conical section joint. On the basis of the shearing spinning sine law and the plastic forming isovolumetric deformation principle, full-size chain design and optimization of the integrally-formed thin-walled cylindrical part spinning blank with the conical section connector are completed, and integrated precise spinning forming machining of the thin-walled cylindrical part with the conical section connector and a complex structure can be efficiently and conveniently achieved through the blank. The defects that in the prior art, machining precision is poor, welding defect risks exist, the period is long and cost is high are overcome, and the problems that when the spinning roller rotates, concave-convex edges are generated on a blank, and reverse extrusion is generated are effectively solved. According to the method, the shearing spinning sine law and the metal plastic deformation isovolumetric flow principle are ingeniously applied, so that the conical section of the product can be formed in a spinning mode at a time, and the high precision of the product size and the consistency of the wall thickness and the diameter are perfectly guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of spinning processing and manufacturing of thin-walled rotating body-like metal components, in particular to a design method for a spinning blank of an integrally formed thin-walled cylindrical component with a tapered section joint. Background Art

[0002] In recent years, with the rapid development and continuous improvement of my country's aviation, aerospace and new weapon system capabilities, the structure of solid rocket engines has become more and more sophisticated and complex. As the main power unit for launch vehicles and weapons, the construction of national defense capabilities has also put forward higher requirements on the comprehensive performance of solid rocket engines. The metal shell of the solid rocket engine is its core structure. It is both a storage box for solid propellant and a combustion chamber during launch. When in use, the shell is subjected to the harsh environment of high temperature and high pressure. Therefore, the reliability of the shell is the decisive factor in the performance of the solid rocket engine.

[0003] Common solid motor casings include a complex structure thin-walled metal rotating body with a conical joint, such as the attached Figure 1 The thin-walled cylindrical part is made of a certain grade of high-strength steel and has a complex structure. It consists of a joint of a thin-walled straight cylinder section with equal wall thickness and a thin-walled tapered cylinder section with equal wall thickness. The diameter and wall thickness accuracy of the cylindrical part are strictly required. The wall thickness accuracy is required to be ±0.1mm, and the diameter accuracy is required to be ±0.2mm. The tapered section has a certain taper. The product has high quality and accuracy consistency requirements, thin wall thickness, complex structure, and strict dimensional accuracy requirements.

[0004] At present, for this kind of complex structure thin-walled cylindrical parts with tapered joints, the traditional tapered joint machining + straight barrel section spinning welding method is generally used for processing. It is difficult to clamp the thin-walled tapered joints with equal wall thickness by machining and it is very easy to deform. The wall thickness and diameter of the tapered section cannot meet the design accuracy requirements, and it will result in low raw material utilization and long processing cycle. After the tapered joint and the straight barrel section are welded, a circumferential weld will be added, which has the risk of welding defects and reduces the overall performance of the cylinder. The machining + spinning welding method has a complex process and requires coordination of multiple workshops and multiple processes. The whole process has a long processing cycle and high processing cost, which affects the efficiency and cost of batch production. Summary of the invention

[0005] In order to overcome the disadvantages of the prior art in forming such complex structure thin-walled cylindrical parts with tapered joints, such as great difficulty in forming, poor processing accuracy, risk of welding defects, long process cycle and high cost, the present invention proposes a design method for spinning blanks of thin-walled cylindrical parts with tapered joints formed in one piece.

[0006] The specific process of the present invention is as follows:

[0007] Step 1: Determine the shape of the spinning blank:

[0008] The spinning blank is a cylindrical part with equal wall thickness, which is divided into a front joint blank section, a cone section blank section and a tail straight barrel section blank section according to its function.

[0009] The outer contour of the front joint billet is consistent with the outer contour of the front joint of the product.

[0010] The outer contour of the cone segment billet is a large cone angle cone tube segment, which is used to form a thin-walled cone tube segment with a cone segment joint.

[0011] The cone angle of the cone section is greater than the cone angle of the thin-walled metal shell, and the wall thickness is greater than the wall thickness of the thin-walled metal shell.

[0012] The outer contour of the tail straight tube section billet is a straight tube section with equal wall thickness, which is used to form products with equal wall thickness and thin wall straight tube sections.

[0013] The wall thickness of the straight tube section with equal wall thickness is greater than the wall thickness of the thin-walled metal shell.

[0014] Step 2: Design of the wall thickness of the spinning blank:

[0015] The wall thickness of the front joint billet is consistent with the wall thickness of the front joint of the product.

[0016] The wall thickness of the cone section billet is the same as that of the tail straight section billet, and the specific design process is:

[0017] According to formula (3), according to the workpiece wall thickness t f And the material section shrinkage rate ψ can be used to obtain the limit wall thickness of the spun blank.

[0018] t0 <t f (1+ψ / 0.17) (3)

[0019] In formula (3), t0 is the wall thickness of the spinning blank, mm; t f is the wall thickness of the workpiece, mm; ψ is the material section shrinkage, %;

[0020] The design of the wall thickness of the conical section billet and the wall thickness of the tail straight section billet follows the principle of formula (3), that is, the wall thickness of the billet is less than the limit wall thickness of the spinning blank.

[0021] The specific derivation process of formula (3) is:

[0022] The thinning rate of the spinning process is less than the material limit thinning rate. The thinning rate is determined by formula (1):

[0023] ψ t =(t0-t f ) / t0<ψ tmax (1)

[0024] Where: t ——Thinning rate, %;

[0025] t0——spinning blank wall thickness, mm;

[0026] t f ——Workpiece wall thickness, mm;

[0027] ψ tmax ——limit thinning rate, %;

[0028] The limit thinning rate is determined by formula (2):

[0029] ψ tmax =(t0-t min ) / t0≈ψ / (0.17+ψ) (2)

[0030] Where: tmax ——limit thinning rate, %;

[0031] t0——spinning blank wall thickness, mm;

[0032] t min ——Minimum wall thickness of workpiece, mm;

[0033] ψ——Material section shrinkage, %;

[0034] Combining equation (1) and equation (2) we get equation (3).

[0035] Step 3: Optimize the structure and size of the spinning blank cone segment:

[0036] Ⅰ Optimize the billet structure of the cone section of the spinning blank:

[0037] The turning point M and the cone segment transition point N are set on the blank cone segment.

[0038] The starting point M is the point where the spinning wheel starts to spin during spinning; the starting point M is located at the junction of the straight section and the tapered section of the front joint of the product; this position can effectively avoid the appearance quality problems of pits and ridges on the product.

[0039] The cone segment transition point N is located at the intersection of the inner arc segment and the cone segment of the blank and is projected onto the outer cone segment of the blank. The cone segment of the spinning blank is divided into a transition spinning cone segment and a stable spinning cone segment through the cone segment transition point N.

[0040] Ⅱ Determine the size of the cone section of the spinning blank:

[0041] The billet size of the cone segment of the spinning blank includes the cone angle and length of the cone segment.

[0042] iDetermine the taper angle of the taper segment blank

[0043] The taper angle includes the taper angle β of the blank stable spinning taper section and the taper angle γ of the blank transition spinning taper section.

[0044] The blank thickness of the cone segment is determined to be t0, and the cone angle β of the blank for stable spinning of the cone segment is determined according to formula (7);

[0045]

[0046] Where: t f is the wall thickness of the product; t0 is the wall thickness of the spun blank; α is the taper angle of the product.

[0047] When determining the taper angle γ of the blank transition spinning cone segment, a line is drawn between the spinning point M and the cone segment transition point N. The angle between the line and the blank axis is the taper angle γ of the blank transition spinning cone segment.

[0048] The specific derivation process of formula (7) is:

[0049] When the cone section of the spinning blank is sheared, the change of the wall thickness of the cone section of the spinning blank follows the sine law, that is,

[0050] t f =t0sinα (4)

[0051] Reducing the taper angle of the workpiece is obtained by means of a preform; wherein the relationship between the product and the preform is:

[0052]

[0053] So there is

[0054]

[0055] Where: t1 is the wall thickness of the preform; β is the taper angle of the spun blank.

[0056] The wall thickness t1 of the preform is equal to the wall thickness t0 of the spun blank.

[0057] ii. Determine the length of the cone segment blank

[0058] The starting point of the cone segment billet length is the intersection of the straight section of the front joint of the product and the cone segment; the intersection coincides with the rotation point M, and the end point of the cone segment billet length is the intersection of the cone segment and the straight section of the barrel section of the product.

[0059] The length of the transition spinning cone section is h1, the length of the stable spinning cone section is h2, and the total length of the cone section blank is h.

[0060] The length of the cone segment blank is determined by equations (10) and (14).

[0061] h=h1+h2 (10)

[0062]

[0063]

[0064] The length h1 of the transitional spun cone section and the length h2 of the stable spun cone section are obtained by the length H of the product cone section and the outer radius R5 and inner radius R6 of the large end of the cone section, the outer radius r5 and inner radius r6 of the small end of the cone section, the outer radius R1 and inner radius R2 of the large end of the transitional spun cone section, the outer radius r1 and inner radius r2 of the small end, the outer radius R3 and inner radius R4 of the large end of the stable spun cone section, and the outer radius r3 and inner radius r4 of the small end.

[0065] The length of the cone segment blank is h=h1+h2.

[0066] The specific derivation process of formula (14) is:

[0067] The volume of the blank and the product in spinning follows the principle of constant volume, that is,

[0068] V 毛坯锥段 =V 产品锥段 (8)

[0069] The spinning blank cone segment consists of a transition spinning cone segment and a stable spinning cone segment, namely

[0070] V 毛坯锥段 =V 过渡旋压锥段 +V 稳定旋压锥段 (9)

[0071] h=h1+h2 (10)

[0072] Assume that both the billet cone section and the product cone section are hollow thin-walled frustum, and determine V by the hollow thin-walled frustum volume calculation formula. 过渡旋压锥段 、V 稳定旋压锥段 and V 产品锥段 ,Right now

[0073]

[0074] In the formula, h1 is the length of the transition spinning cone section; R1 is the outer radius of the large end of the transition spinning cone section; r1 is the outer radius of the small end of the transition spinning cone section; R2 is the inner radius of the large end of the transition spinning cone section; r2 is the inner radius of the small end of the transition spinning cone section; h2 is the length of the stable spinning cone section; R3 is the outer radius of the large end of the stable spinning cone section; r3 is the outer radius of the small end of the stable spinning cone section; R4 is the inner radius of the large end of the stable spinning cone section; r4 is the inner radius of the small end of the stable spinning cone section; H is the length of the product cone section; R5 is the outer radius of the large end of the product cone section; r5 is the outer radius of the small end of the product cone section; R6 is the inner radius of the large end of the product cone section; r6 is the inner radius of the small end of the product cone section.

[0075] Combining equations (8) to (13), we get equation (14):

[0076] Step 4: Determine the overall size of the spinning blank:

[0077] Through steps 1 to 3, the wall thickness of the cone section of the spun blank and the wall thickness of the tail straight tube section t0, the cone angle γ and length h1 of the blank transition spun cone section, the cone angle β and length h2 of the blank stable spun cone section, and the total length h of the blank cone section are determined respectively.

[0078] In the spinning blank, the length of the front joint billet in the blank is the same as the length of the front joint of the product, and the length of the tail straight barrel billet is the same as the length of the tail straight barrel of the product;

[0079] The total length L of the determined spinning blank = the length of the front joint blank section + the length of the tail straight barrel section blank section + the length of the transition spinning cone section h1 + the length of the stable spinning cone section h2.

[0080] The inner diameter of the determined spinning blank is consistent with the inner diameter of the product.

[0081] The straightness and roundness of the inner surface of the straight section of the spun blank are determined to be 0.03mm, the coaxiality of the tapered section and the straight section is less than 0.03mm, and the roughness of the inner and outer surfaces is required to be Ra1.6.

[0082] At this point, the design of the spinning blank of the thin-walled cylindrical part with a tapered section joint has been completed.

[0083] The present invention uses the blank to efficiently and conveniently realize the integrated precision spinning forming of a thin-walled cylindrical part with a complex structure and a tapered section joint.

[0084] Aiming at the integrated spinning forming of complex thin-walled cylindrical parts with tapered joints, the present invention proposes a spinning blank structure design method, which is specifically based on the size requirements of the processed thin-walled cylinder, the shear spinning sine law and the volume deformation principle such as plastic forming to complete the full-size chain design and optimization of the spinning blank of the integrated thin-walled cylindrical part with tapered joint.

[0085] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0086] The spun blank with joint accessory structure designed in the present invention can realize the integrated spinning forming of thin-walled cylindrical parts with complex structure of tapered joints, avoiding a series of disadvantages caused by the traditional forming method of machining tapered joints + straight barrel section spinning and welding, such as poor product processing accuracy, risk of welding defects, long cycle and high cost of the whole process; the spun blank designed in the present invention has a transition designed between the front joint section and the tapered section, which effectively solves the problem of concave and convex edges and back extrusion of the blank due to the sharp increase in spinning pressure when the spinning wheel is spinning; the tapered section of the spun blank designed in the present invention cleverly uses the shear spinning sine law and volume flow principles such as metal plastic deformation, so that the product tapered section can be spun in one time, perfectly ensuring the high accuracy of product size and the consistency of wall thickness and diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 Schematic diagram of the structure of a thin-walled metal shell with a tapered joint.

[0088] Figure 2 Schematic diagram of the spinning blank structure of the present invention.

[0089] Figure 3 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0090] This embodiment is a spinning blank for processing a thin-walled metal shell with a tapered section joint. The thin-walled metal shell with a tapered section joint is composed of a complex structure joint of a thin-walled straight tube section with equal wall thickness and a thin-walled tapered tube section with equal wall thickness.

[0091] The spun blank proposed in this embodiment can integrally form the thin-walled metal shell with the tapered section joint.

[0092] The material of the thin-walled metal shell of the taper joint is 30Cr3SiNiMoV, and the outer diameter of the cylindrical part is Inner diameter The taper angle of the taper section of the joint is 2.56°, and the outer diameter of the straight section of the joint is The wall thickness of the conical section and the straight section is 2.35±0.1mm, and the length of the conical section is required to be 203±1mm. The specific process of this embodiment is:

[0093] The specific process of the present invention is as follows:

[0094] Step 1: Determine the shape of the spinning blank:

[0095] The spinning blank is a cylindrical part with equal wall thickness, which is divided into a front joint blank section, a cone section blank section and a tail straight barrel section blank section according to its function.

[0096] The front joint billet does not participate in the plastic deformation of the spinning process, so the outer contour of the front joint billet is consistent with the outer contour of the front joint of the product.

[0097] The outer contour of the cone segment billet is a large cone-angle cone barrel segment, which is used for shearing the thin-walled cone barrel segment with a cone segment joint of the spinning product during the spinning process. The cone barrel segment has a cone angle greater than the cone angle of the thin-walled metal shell, and a wall thickness greater than the wall thickness of the thin-walled metal shell.

[0098] The tail straight tube section blank has an outer contour of an equal wall thickness straight tube section, which is used to thin the equal wall thickness thin wall straight tube section of the spinning formed product during the spinning process. The wall thickness of the equal wall thickness straight tube section is greater than the wall thickness of the thin wall metal shell.

[0099] Step 2: Design of the wall thickness of the spinning blank:

[0100] The front joint billet does not participate in the plastic deformation during the spinning process, so the wall thickness of the front joint billet is consistent with the wall thickness of the front joint of the product.

[0101] The wall thickness of the cone section billet is the same as that of the tail straight section billet, and the specific design process is:

[0102] According to formula (3), according to the workpiece wall thickness t f And the material section shrinkage rate ψ can be used to obtain the limit wall thickness of the spun blank.

[0103] t0 <t f (1+ψ / 0.17) (3)

[0104] The design of the wall thickness of the conical section billet and the wall thickness of the tail straight section billet follows the principle of formula (3), that is, the wall thickness of the billet is less than the limit wall thickness of the spinning blank.

[0105] The specific derivation process of formula (3) is:

[0106] The thinning rate of the spinning process is less than the material limit thinning rate. The thinning rate is determined by formula (1):

[0107] ψ t =(t0-t f ) / t0<ψ tmax (1)

[0108] Where: t ——Thinning rate, %;

[0109] t0——spinning blank wall thickness, mm;

[0110] t f ——Workpiece wall thickness, mm;

[0111] ψ tmax ——limit thinning rate, %;

[0112] The limit thinning rate is determined by formula (2):

[0113] ψtmax =(t0-t min ) / t0≈ψ / (0.17+ψ) (2)

[0114] Where: tmax ——limit thinning rate, %;

[0115] t0——spinning blank wall thickness, mm;

[0116] t min ——Minimum wall thickness of workpiece, mm;

[0117] ψ——Material section shrinkage, %;

[0118] Combining equation (1) and equation (2) we get equation (3)

[0119] t0 <t f (1+ψ / 0.17) (3)

[0120] The material of the product in this embodiment is 30Cr3SiNiMoV high-strength steel, and its cross-sectional shrinkage rate ψ=45%; The required wall thickness of the product is t f =2.35mm, according to formula (3), the limit wall thickness of the spun blank is calculated to be 8.57mm.

[0121] In this embodiment, the wall thickness of the conical section billet and the wall thickness of the tail straight tube section billet t0=5.5mm<8.57mm, and the conical section billet and the tail straight tube section billet with this wall thickness are rotatable.

[0122] Step 3: Optimize the structure and size of the spinning blank cone segment:

[0123] Ⅰ Optimize the billet structure of the cone section of the spinning blank:

[0124] In order to achieve a good processing effect of the spinning blank and avoid pits, convex edges and back extrusion in the product, the present invention sets a spinning starting point M and a cone section transition point N on the cone section of the blank.

[0125] The starting point M is the point where the spinning wheel starts to spin during spinning; the starting point M is located at the junction of the straight section and the tapered section of the front joint of the product, and this position can effectively avoid the appearance quality problems of pits and ridges on the product.

[0126] The cone segment transition point N is located at the intersection of the inner arc segment and the cone segment of the blank and is projected onto the outer cone segment of the blank. The cone segment of the spinning blank is divided into a transition spinning cone segment and a stable spinning cone segment through the cone segment transition point N.

[0127] Ⅱ Determine the size of the cone section of the spinning blank:

[0128] The billet size of the cone segment of the spinning blank includes the cone angle and length of the cone segment.

[0129] According to the design, the wall thickness, cone angle and length of the product cone segment are 2.35 mm, 2.56° and 203 mm respectively. The cone angle and length of the cone segment billet are determined according to the wall thickness, cone angle and length of the product cone segment.

[0130] iDetermine the taper angle of the taper segment blank

[0131] The blank thickness of the cone segment is determined to be t0, and the cone angle β of the cone segment is determined according to formula (7);

[0132]

[0133] Where: t f is the wall thickness of the product; t0 is the wall thickness of the spun blank; α is the taper angle of the product.

[0134] The specific derivation process of formula (7) is:

[0135] When the cone section of the spinning blank is sheared, the change of the wall thickness of the cone section of the spinning blank follows the sine law, that is,

[0136] t f =t0sinα (4)

[0137] Reducing the taper angle of the workpiece is obtained by means of a preform; wherein the relationship between the product and the preform is:

[0138]

[0139] So there is

[0140]

[0141] Where: t1 is the wall thickness of the preform; β is the taper angle of the spun blank.

[0142] The wall thickness t1 of the preform is the wall thickness t0 of the spinning blank, that is,

[0143]

[0144] In this embodiment, the wall thickness of the product is f =2.35mm, the cone angle of the product is α = 2.56°, the wall thickness of the spinning blank cone section is t0 = 5.5mm, and the cone angle of the spinning blank cone section is calculated according to formula (7):

[0145] The cone angle β of the spinning blank cone segment is the cone angle of the stable spinning cone segment.

[0146] The cone angle γ of the transition spinning cone segment is determined by the spinning starting point M and the cone segment transition point N.

[0147] In this embodiment, the cone angle γ of the transition spinning cone section is 8.6°.

[0148] ii. Determine the length of the cone segment blank

[0149] The starting point of the cone segment billet length is the intersection of the straight section of the front joint of the product and the cone segment; the intersection coincides with the rotation point M, and the end point of the cone segment billet length is the intersection of the cone segment and the straight section of the barrel section of the product.

[0150] The length of the transition spinning cone section is h1, the length of the stable spinning cone section is h2, and the total length of the cone section blank is h.

[0151] The length of the cone segment blank is determined by equations (10) and (14).

[0152] h=h1+h2 (10)

[0153]

[0154]

[0155] The specific derivation process of formula (14) is:

[0156] The volume of the blank and the product in spinning follows the principle of constant volume, that is,

[0157] V 毛坯锥段 =V 产品锥段 (8)

[0158] The spinning blank cone segment consists of a transition spinning cone segment and a stable spinning cone segment, namely

[0159] V 毛坯锥段 =V 过渡旋压锥段 +V 稳定旋压锥段 (9)

[0160] h=h1+h2 (10)

[0161] Assume that both the billet cone section and the product cone section are hollow thin-walled frustum, and determine V by the hollow thin-walled frustum volume calculation formula. 过渡旋压锥段 、V 稳定旋压锥段 and V 产品锥段 ,Right now

[0162]

[0163] In the formula, h1 is the length of the transition spinning cone section; R1 is the outer radius of the large end of the transition spinning cone section; r1 is the outer radius of the small end of the transition spinning cone section; R2 is the inner radius of the large end of the transition spinning cone section; r2 is the inner radius of the small end of the transition spinning cone section; h2 is the length of the stable spinning cone section; R3 is the outer radius of the large end of the stable spinning cone section; r3 is the outer radius of the small end of the stable spinning cone section; R4 is the inner radius of the large end of the stable spinning cone section; r4 is the inner radius of the small end of the stable spinning cone section; H is the length of the product cone section; R5 is the outer radius of the large end of the product cone section; r5 is the outer radius of the small end of the product cone section; R6 is the inner radius of the large end of the product cone section; r6 is the inner radius of the small end of the product cone section.

[0164] Combining equations (8) to (13), we can get

[0165] h1[(R1 2 +R1r1+r1 2 )-(R2 2 +R2r2+r2 2 )]+h2[(R3 2 +R3r3+r3 2 )-(R4 2 +R4r4+r4 2 )]=H[(R5 2 +R5r5+r5 2 )-(R6 2 +R6r6+r6 2 )] (14)

[0166] The length h1 of the transitional spun cone section and the length h2 of the stable spun cone section are obtained by the length H of the product cone section and the outer radius R5 and inner radius R6 of the large end of the cone section, the outer radius r5 and inner radius r6 of the small end of the cone section, the outer radius R1 and inner radius R2 of the large end of the transitional spun cone section, the outer radius r1 and inner radius r2 of the small end, the outer radius R3 and inner radius R4 of the large end of the stable spun cone section, and the outer radius r3 and inner radius r4 of the small end.

[0167] The length of the cone segment blank is h=h1+h2.

[0168] In this embodiment, the length of the transition spinning cone section in the blank cone section is h1=36.7mm, the length of the stable spinning cone section is h2=62.8mm, and the length of the blank cone section is h=h1+h2=99.5mm.

[0169] Step 4: Determine the overall size of the spinning blank:

[0170] Through steps 1 to 3, the wall thickness of the cone section of the spun blank and the wall thickness of the tail straight tube section are determined to be t0 = 5.5mm, the cone angle γ of the blank transition spun cone section is 8.6°, the length h1 = 36.7mm, the cone angle β of the blank stable spun cone section is 6°, the length h2 = 62.8mm, and the total length of the blank cone section is h = 99.5mm.

[0171] The inner diameter of the spinning blank is determined to be consistent with the inner diameter of the product, which is Φ295.30 +0.1 mm.

[0172] The total length of the spun blank was determined to be L = 350 mm.

[0173] The straightness and roundness of the inner surface of the straight section of the spun blank are determined to be 0.03mm, the coaxiality of the tapered section and the straight section is less than 0.03mm, and the roughness of the inner and outer surfaces is required to be Ra1.6.

[0174] At this point, the design process of the spinning blank of the thin-walled cylindrical part with a tapered joint has been completed. The blank structure is shown in the attached figure. Figure 2 shown.

Claims

1. A design method for spinning a thin-walled cylindrical part with a tapered joint, characterized in that: The specific process is as follows: Step 1: Determine the shape of the spinning blank: The spinning blank is a cylindrical part with equal wall thickness, which is divided into a front joint blank, a cone section blank and a tail straight section blank according to its function; The outer contour of the front joint billet is consistent with the outer contour of the front joint of the product; The outline of the cone segment billet is a cone segment with a large cone angle, which is used to form a thin-wall cone segment with a cone segment joint; The cone angle of the cone section is greater than the cone angle of the thin-walled metal shell, and the wall thickness is greater than the wall thickness of the thin-walled metal shell; The tail straight tube section billet has an outer contour of a straight tube section with equal wall thickness, which is used to form products with equal wall thickness and thin wall straight tube sections; The wall thickness of the straight tube section with equal wall thickness is greater than the wall thickness of the thin-walled metal shell; Step 2: Design of the wall thickness of the spinning blank: The wall thickness of the front joint billet is consistent with the wall thickness of the front joint of the product; The wall thickness of the cone section billet is the same as that of the tail straight section billet, and the specific design process is: According to formula (3), according to the workpiece wall thickness t f The limiting wall thickness of the spinning blank is obtained by the material section shrinkage rate ψ; t0<t f (1+ψ / 0.17) (3) In formula (3), t0 is the wall thickness of the spinning blank, mm; t f is the wall thickness of the workpiece, mm; ψ is the cross-sectional shrinkage of the material, %; the wall thickness of the conical section billet and the wall thickness of the tail straight section billet are designed according to the principle of formula (3), that is, the wall thickness of the billet is less than the limit wall thickness of the spinning blank; Step 3: Optimize the structure and size of the spinning blank cone segment: Ⅰ Optimize the billet structure of the spinning blank cone segment: Set the starting point M and the transition point N of the cone segment on the blank cone segment; Ⅱ Determine the size of the cone section of the spinning blank: The billet size of the spinning blank cone segment includes the cone angle and length of the billet; iDetermine the taper angle of the taper segment blank The taper angle includes the taper angle β of the blank stable spinning taper segment and the taper angle γ of the blank transition spinning taper segment; The blank thickness of the cone segment is determined to be t0, and the cone angle β of the blank for stable spinning of the cone segment is determined according to formula (7); Where: t f is the wall thickness of the product; t0 is the wall thickness of the spun blank; α is the taper angle of the product; when determining the taper angle γ of the blank transition spun cone segment, a line is drawn between the starting point M and the cone segment transition point N, and the angle between the line and the blank axis is the taper angle γ of the blank transition spun cone segment; the wall thickness t1 of the preform is the wall thickness t0 of the spun blank; ii. Determine the length of the cone segment blank The starting point of the length of the cone segment billet is the intersection of the straight section of the front joint of the product and the cone segment; the intersection coincides with the rotation point M, and the end point of the length of the cone segment billet is the intersection of the cone segment and the straight section of the barrel section of the product; The length of the transition spinning cone section is h1, the length of the stable spinning cone section is h2, and the total length of the cone section blank is h; the length of the cone section blank is determined by equations (10) and (14); h=h1+h2 (10) The length h1 of the transition spinning cone section and the length h2 of the stable spinning cone section are obtained by the length H of the product cone section and the outer radius R5 and inner radius R6 of the large end of the cone section, the outer radius r5 and inner radius r6 of the small end of the cone section, the outer radius R1 and inner radius R2 of the large end of the transition spinning cone section, the outer radius r1 and inner radius r2 of the small end, the outer radius R3 and inner radius R4 of the large end of the stable spinning cone section, and the outer radius r3 and inner radius r4 of the small end; The length of the cone segment blank is h = h1 + h2; Step 4: Determine the overall size of the spinning blank: Through steps 1 to 3, the wall thickness of the conical section of the spinning blank and the wall thickness of the tail straight section t0, the taper angle γ and length h1 of the transition spinning taper section of the blank, the taper angle β and length h2 of the stable spinning taper section of the blank, and the total length h of the taper section of the blank are determined respectively; The total length of the spun blank determined is L = the length of the front joint blank section + the length of the tail straight barrel section blank section + the length of the transitional spun cone section h1 + the length of the stable spun cone section h2; The inner diameter of the determined spinning blank is consistent with the inner diameter of the product; The straightness and roundness of the inner surface of the straight section of the spinning blank are determined to be 0.03mm, the coaxiality of the tapered section and the straight section is less than 0.03mm, and the roughness of the inner and outer surfaces is required to be Ra1.6; At this point, the design of the spinning blank of the thin-walled cylindrical part with a tapered section joint has been completed.

2. The design method of the spinning blank of the integrally formed thin-walled cylindrical joint with a tapered section as claimed in claim 1 is characterized in that: The specific derivation process of formula (3) in step 2 is: The thinning rate of the spinning process is less than the material limit thinning rate. The thinning rate is determined by formula (1): ψ t =(t0-t f ) / t0<ψ tmax (1) Where: t is the thinning rate, %; t 0为 Spinning blank wall thickness, mm; t f为 Workpiece wall thickness, mm; ψ tmax is the limit thinning rate, %; The limit thinning rate is determined by formula (2): ψ tmax =(t0-t min ) / t0≈ψ / (0.17+ψ) (2) Where: tmax is the limit thinning rate, %; t0 is the wall thickness of the spinning blank, mm; t min is the minimum wall thickness of the workpiece, mm; ψ is the material section shrinkage, %; Combining equation (1) and equation (2) we get equation (3).

3. The design method of the spinning blank of the integrally formed thin-walled cylindrical joint with a tapered section as claimed in claim 1 is characterized in that: The starting point M described in step 3 is the point where the spinning wheel starts to spin during spinning; the starting point M is located at the junction of the straight section and the cone section of the front joint of the product; this position can effectively avoid the appearance quality problems of pits and ridges in the product; the cone section transition point N is located at the position where the intersection of the arc section and the cone section of the inner surface of the blank is projected to the cone section of the outer surface; through the cone section transition point N, the cone section of the spun blank is divided into a transition spinning cone section and a stable spinning cone section.

4. The design method of the spinning blank of the integrally formed thin-walled cylindrical joint with a tapered section as claimed in claim 1 is characterized in that: In step 3, the specific derivation process of formula (7) is: When the cone section of the spinning blank is sheared, the change of the wall thickness of the cone section of the spinning blank follows the sine law, that is, t f =t0sinα (4) Reducing the taper angle of the workpiece is obtained by means of a preform; wherein the relationship between the product and the preform is: Therefore Where: t1 is the wall thickness of the preform; β is the taper angle of the spun blank.

5. The design method of the spinning blank of the integrally formed thin-walled cylindrical joint with a tapered section as claimed in claim 1, characterized in that: In step 3, the specific derivation process of formula (14) is: The volume of the blank and the product in spinning follows the principle of constant volume, that is, V 毛坯锥段 =V 产品锥段 (8) The spinning blank cone segment consists of a transition spinning cone segment and a stable spinning cone segment, namely V 毛坯锥段 =V 过渡旋压锥段 +V 稳定旋压锥段 (9) h=h1+h2 (10) Assume that both the billet cone section and the product cone section are hollow thin-walled frustum, and determine V by the hollow thin-walled frustum volume calculation formula. 过渡旋压锥段 、V 稳定旋压锥段 and V 产品锥段 ,Right now Wherein, h1 is the length of transition spinning cone section; R1 is the outer radius of the large end of transition spinning cone section; r1 is the outer radius of the small end of transition spinning cone section; R2 is the inner radius of the large end of transition spinning cone section; r2 is the inner radius of the small end of transition spinning cone section; h2 is the length of stable spinning cone section; R3 is the outer radius of the large end of stable spinning cone section; r3 is the outer radius of the small end of stable spinning cone section; R4 is the inner radius of the large end of stable spinning cone section; r4 is the inner radius of the small end of stable spinning cone section; H is the length of product cone section; R5 is the outer radius of the large end of product cone section; r5 is the outer radius of the small end of product cone section; R6 is the inner radius of the large end of product cone section; r6 is the inner radius of the small end of product cone section; Combining equations (8) to (13) yields equation (14).

6. The design method of the spinning blank of the integrally formed thin-walled cylindrical joint with a tapered section as claimed in claim 1, characterized in that: In the spun blank, the length of the front joint billet section in the blank is the same as the length of the front joint of the product, and the length of the tail straight tube billet section is the same as the length of the tail straight tube section of the product.

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