Reshaping and tempering method for complex distortion of ultra-high-strength steel thin-wall large-length-diameter-ratio shell

Abstract

The invention discloses a shaping and tempering method for complex distortion of an ultra-high-strength steel thin-wall large-length-diameter-ratio shell, which comprises the following steps of: taking N sub-sections in the length direction of the shell, measuring circle run-out data of the N sub-sections on a lathe by taking a circle run-out high point in a length center area as a quadrant starting point, and calculating the circle run-out data of the N sub-sections by taking 45 degrees as a period; eight point positions which are evenly distributed are included. According to the method, synchronous correction of coaxial bending deformation and ovality deformation of the shell can be synchronously achieved during first tempering, and the requirement for heat treatment size precision of the shell is effectively met.

Description

Technical Field

[0001] The invention belongs to the technical field of heat treatment, and relates to a shaping and tempering method for a complexly distorted ultra-high strength steel thin-wall large aspect ratio shell. Background Art

[0002] Ultra-high strength steel can be used to make thin-walled combustion chamber shells, and D406A is a typical type of ultra-high strength alloy steel. In order to ensure the mechanical properties of the welding area, the combustion chamber shell needs to be quenched and tempered as a whole after welding.

[0003] During the quenching process, the temperature must be heated to above the austenitizing temperature, and then the martensitic structure is obtained by rapid cooling. The thermal stress and phase change stress generated during the quenching heating process are superimposed on the residual stress generated in the previous forming and machining processes, resulting in high-temperature plastic or creep deformation; the quenching cooling boundary conditions of complex structure shells are uneven, resulting in non-uniform rapid cooling volume deformation. In heat treatment production, heat treatment distortion is difficult to be completely controlled.

[0004] For thin-walled parts with a large aspect ratio, due to their structural characteristics, the distortion after quenching is more serious, which makes subsequent processing and assembly difficult.

[0005] The heat treatment distortion of the combustion chamber shell is inconsistent. At the same time, the shell may have functional structures such as thickened areas, guide blocks, and supports. The shape correction and clamping process should have a certain degree of flexibility.

[0006] With the goal of circular runout ≤2.5mm, the existing heat treatment deformation shaping technology for the combustion chamber shell can only achieve ovality shaping, but cannot handle the complex heat treatment distortion caused by the coexistence of ovality deformation and coaxial bending deformation ≥2mm.

[0007] Traditional shaping methods often require multiple shaping, the production rhythm is uncontrollable, it is highly dependent on skilled technical workers, the production efficiency is low, and the portability of heat treatment capabilities is poor; for ultra-high strength alloy steels such as D406A, the secondary shaping effect will decay rapidly, and after multiple shaping, the shape and size accuracy may still not be met, which will cause the product to be scrapped.

[0008] Since the traditional heat treatment shaping method has a small envelope, in order to ensure the progress of product development, it is necessary to control the heat treatment distortion within a smaller range through process methods or processes such as segmented spinning + welding, multiple stress relief annealing, and high-pressure gas quenching, and avoid coaxial bending deformation as much as possible. This leads to a complex upstream process chain, high equipment investment, low production efficiency, and high production cost, which greatly restricts "cost reduction and efficiency improvement" and is not suitable for mass production. Summary of the invention

[0009] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a shaping and tempering method for complex distortion of ultra-high strength steel thin-walled shells with large aspect ratio.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] A shaping and tempering method for complex distortion of ultra-high strength steel thin-walled large aspect ratio shell, comprising the following steps

[0012] S1. Take N sub-sections in the length direction of the shell, take the high point of the circular runout in the length center area as the quadrant starting point, and measure the circular runout data of the N sub-sections on a lathe. The circular runout data has a period of 45° and includes 8 evenly distributed points.

[0013] S2. According to the circular runout data and the theoretical radius, the initial ellipse equation of each section is fitted, avoiding the guide block, support and other structures on the shell, selecting the shaping area and the support area according to the coefficient of the initial ellipse equation, calculating the ellipse according to the major axis and minor axis radii, and marking the ellipse tolerance area as the ellipse shaping area;

[0014] S3. Calculate the target ellipse equation expected to be in place after shaping based on the ellipse equation coefficients of the shaping area and the support area, and calculate the amount of bolt downward pressure that should be applied by the shaping tool based on the initial ellipse equation and the target ellipse equation; the shaping tool is a common tool in the industry, and a full set of shaping tools includes components such as slide rails, support shaping tools and clamp tools.

[0015] S4. Install a rigid reinforcement clamp in the support area, install a support shaping tool in the shaping area, and install a clamp shaping tool in the section with excessive ovality;

[0016] S5. After the tooling is installed, the shell and the tooling are tempered together;

[0017] S6. After tempering, remove the tooling and measure the circular runout of each section. If the circular runout of each section is within the design index range, the shaping is completed, otherwise, repeat steps S1-S5 for secondary shaping.

[0018] As a preferred embodiment, in step S1, the N sub-sections have a section spacing of 300-500 mm.

[0019] As a preferred embodiment, the shell adopts ultra-high strength steel grade D406A.

[0020] As a preferred embodiment, in step S5, the tempering temperature is 300±20° C. and the time is 3 hours.

[0021] As a preferred method, in step S2, according to the circular runout measurement data and theoretical outer diameter r o The polar coordinate radius value corresponding to each quadrant can be calculated The calculation formula is as follows:

[0022]

[0023] After converting polar coordinates to rectangular coordinates, the implicit function nonlinear ellipse fitting of Origin software is used to fit the ellipse equation. The ellipse equation is:

[0024]

[0025] In the ellipse equation, (x0, y0) are the coordinates of the center of the ellipse, and a and b are the radii of the x-axis and y-axis respectively.

[0026] In step S3, firstly, the center coordinates of the target ellipse [x0(Max), y0(Max)] are calculated based on the center coordinates of the initial ellipse in the calibration area [x0(Max), y0(Max)]. c ,y c ]:

[0027]

[0028]

[0029] Where A and B are constants, and S is the force arm distance, that is, the distance between the shaping area and the support area.

[0030] The x-axis radius a of the target shaping ellipse c The radius b of the y axis c The axis radius is calculated according to the following formula:

[0031] a c =a(Max)-C(a(Max)-b(Max))

[0032] b c =b(Max)+C(a(Max)-b(Max))

[0033] In the formula, a(Max) and b(Max) are the x-axis radius and y-axis radius of the initial ellipse equation corresponding to the shaping area, respectively, and C is the roundness correction coefficient, which is related to the shell material, heat treatment state, diameter, thickness and arm distance, and is determined based on experiments or simulations. The target ellipse equation is:

[0034]

[0035] The bolt pressure is calculated by the following formula:

[0036]

[0037] In the formula, is the polar coordinate radius calculated by the initial ellipse equation; is the polar coordinate radius calculated according to the target ellipse equation; is the quadrant angle corresponding to the bolt axis; when the bolt pressure S(θ) is positive, the bolt needs to be pressed down; when the bolt pressure S(θ) is negative, the bolt needs to be loosened.

[0038] For the elliptical shaping area, use an elliptical shaping clamp to perform micro-correction on the elliptical degree so that the x-axis diameter R of the ellipse after shaping x The diameter of the y axis is R y Changes to:

[0039] R x =2×(aC(ab))

[0040] R y =2×(b+C(ab)).

[0041] According to the deformation law of thin-walled shells, the present invention designs a special shaping method with certain process flexibility. The shaping scheme is designed according to the deformation characteristics of the shell, and the shaping process parameters are calculated using the elliptical equation obtained by fitting the circular runout data. Combined with the heat treatment process characteristics of ultra-high strength steel, the coaxial bending deformation and elliptic deformation of the shell can be simultaneously corrected during the first tempering, effectively ensuring the dimensional accuracy requirements of the shell heat treatment.

[0042] The present invention has the following advantages:

[0043] The present invention uses a tooling-assisted tempering shaping method, which is designed as a V-shaped shaping method of "two-point support, center-down pressure". It can flexibly handle functional structures such as guide blocks and supports that are not easy to shape and clamp, and is easy to achieve standardization while taking into account adaptability; the pressing area is designed as a multi-bolt ring pressure, which can simultaneously take into account coaxiality and roundness correction; the initial elliptical equation coefficient of each bolt pressing amount is calculated, and the calculation coefficient is determined by simulation or experiment. This method solves the problems of small envelope range, low efficiency, difficulty in handling straightness deformation, low degree of standardization, poor accuracy, and poor quality stability of traditional shaping methods, and greatly reduces the accuracy requirements for the previous spinning, welding, and heat treatment processes. After shaping, less or no machining is required, which is of great significance to the improvement of the quality and efficiency of the manufacturing process chain of related products. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the process of the present invention;

[0045] Figure 2 This is a schematic diagram of circular runout measurement;

[0046] Figure 3 Schematic diagram of the shaping scheme;

[0047] Figure 4 This is a schematic diagram of the support shaping tooling structure;

[0048] Figure 5 This is a schematic diagram of the clamp shaping tooling structure.

[0049] In the figure: A1-shaping area, A2-support area, A3 ovality correction area, A-slide rail; B-support block; C-annular tooling. DETAILED DESCRIPTION

[0050] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0051] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0052] Example:

[0053] After quenching heat treatment, circular runout measurement is carried out. The measured data are shown in Table 1, that is, circular runout measurement is carried out on 12 groups of measuring circles, a total of 8 evenly distributed quadrant positions, that is, a circular runout data is recorded every 45°, and no special requirements are made for the zero point position of the circular runout measurement.

[0054] According to the above data, the theoretical radius is substituted to calculate the polar coordinate radius corresponding to each quadrant angle, and the ellipse equation is fitted. The obtained ellipse equation coefficients are shown in Table 2. According to the data given in Table 2, the circular runout value of the No. 6 measuring circle (corresponding to a length of 1800mm) is the largest, reaching 7.36mm. The 1700-1900mm area is selected as the shaping area; in order to avoid functional structures such as guide blocks and supports, the 100-300mm area and the 3300-3500mm area are selected as support positions, and the arm distance is 1.6m.

[0055] Table 1 Initial circular runout measurement data

[0056] serial number 1 2 3 4 5 6 7 8 9 10 11 12 Length(mm) 300 600 900 1200 1500 1800 2100 2400 2700 3000 3300 3600 I Quadrant 0 0 0 0 0 0 0 0 0 0 0 0 I→II 6 4.8 5.6 5.2 4.8 5.6 0.8 1.2 .0.4 .0.8 0.8 1.2 Quadrant II 52 4 4.4 1.2 .1.6 .3.6 .5.6 -6 .6.8 .6.4 .4.4 .2.8 II → III 2.8 -1.6 -3.6 -7.2 -9.6 -10.8 -13.2 -11.6 -14 -11.2 -5.2 0.8 Quadrant III -5.6 -9.2 -14 -22 -252 -24.4 -23.6 -20.8 -17.6 -13.6 -8 0 III → IV 0.4 .8.8 -15.6 -22 -24.4 -24.8 -24.8 -21.2 -20.4 -18 -11.2 -32 IV Quadrant -3.2 -4 -5.2 -9.6 -12.8 -15.6 -16.4 -16.4 -14.4 -13.2 -4.8 -2.8 IV→I 7.2 2 0.8 -2.4 -2 -1.2 -2.8 0.4 -4.4 -2.4 2 5.6

[0057] Table 2 Ellipse equation coefficients

[0058] serial number 1 2 3 4 5 6 7 8 9 10 11 12 Length(mm) 300 600 900 1200 1500 1800 2100 2400 2700 3000 3300 3600 <![CDATA[x0]]> 193 3.21 4.71 6.26 682 699 6.21 5.53 472 394 2.23 0.55 <![CDATA[y0]]> -0.31 -0.55 -0.93 -1.57 -2.18 -2.30 -2.44 -2.44 -2.09 -1.71 -1.58 -0.61 a 200.37 199.26 198.61 198.98 198.23 197.68 199.27 199.67 201.04 199.67 199.80 199.29 b 201.30 200.39 200.44 200.84 200.30 199.55 201.35 201.95 201.68 200.99 201.59 201.40

[0059] In this embodiment, the initial ellipse equation is:

[0060]

[0061] The calculation coefficients of the three shaping ellipse equations A / B / C are determined to be 0.3 / 0.0005 / 1.5, and the target ellipse equation corresponding to the depression area is calculated as follows:

[0062]

[0063] The calculated bolt guide pressure gauge is shown in Table 3, and the corresponding bolt number diagram is shown in Figure 4 .

[0064] Table 3 Bolt guide pressure

[0065] Bolt No. 1 2 3 4 5 6 7 11 12 13 14 15 16 Pressure 22.73 18.47 12.60 4.91 -4.50 -14.60 -23.42 -12.08 0.55 12.31 20.78 24.93 25.20

[0066] After printing Table 3, it is handed over to the operator to perform the shaping and clamping operations.

[0067] After clamping, check for loose bolts and remove them to prevent parts from falling during heat treatment.

[0068] Vertically hoist it into the heat treatment furnace for shaping and tempering, and then to the warm loading furnace, the tempering temperature is 300±20℃, and the tempering time is 3h.

[0069] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A shaping and tempering method for complex distortion of ultra-high strength steel thin-walled shell with large aspect ratio, characterized in that: The steps include: S1. Take N sub-sections in the length direction of the shell, take the high point of the circular runout in the length center area as the quadrant starting point, and measure the circular runout data of the N sub-sections on a lathe. The circular runout data has a period of 45° and includes 8 evenly distributed points. S2. According to the circular runout data and the theoretical radius, the initial ellipse equation of each section is fitted, avoiding the guide block, support and other structures on the shell, selecting the shaping area and the support area according to the coefficient of the initial ellipse equation, calculating the ellipse according to the major axis and minor axis radii, and marking the ellipse tolerance area as the ellipse shaping area; S3, according to the ellipse equation coefficients of the shaping area and the support area, calculate the target ellipse equation expected to be in place after shaping, and calculate the bolt pressure amount to be applied by the shaping tool according to the initial ellipse equation and the target ellipse equation; S4. Install a rigid reinforcement clamp in the support area, install a support shaping tool in the shaping area, and install a clamp shaping tool in the section with excessive ovality; S5. After the tooling is installed, the shell and the tooling are tempered together; S6. After tempering, remove the tooling and measure the circular runout of each section. If the circular runout of each section is within the design index range, the shaping is completed, otherwise, repeat steps S1-S5 for secondary shaping.

2. The method for shaping and tempering a complexly distorted ultra-high strength steel thin-walled shell with a large aspect ratio according to claim 1, characterized in that: In the step S1, there are N sub-sections, and the section spacing is 300-500 mm.

3. The method for shaping and tempering a complexly distorted ultra-high strength steel thin-walled shell with a large aspect ratio according to claim 1, characterized in that: The shell is made of ultra-high strength steel grade D406A.

4. The method for shaping and tempering a complexly distorted ultra-high strength steel thin-walled shell with a large aspect ratio according to claim 1, characterized in that: In step S5, the tempering temperature is 300±20° C. and the time is 3 hours.

5. The method for shaping and tempering a complexly distorted ultra-high strength steel thin-walled shell with a large aspect ratio according to claim 1, characterized in that: In step S2, according to the circular runout measurement data Δr(θ) and the theoretical outer diameter r o The polar coordinate radius value r(θ) corresponding to each quadrant can be calculated, and the calculation formula is as follows: r(θ)=r0+Δr(θ) After converting polar coordinates to rectangular coordinates, the implicit function nonlinear ellipse fitting of Origin software is used to fit the ellipse equation. The ellipse equation is: In the ellipse equation, (x0, y0) are the coordinates of the center of the ellipse, and a and b are the radii of the x-axis and y-axis respectively.

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