Titanium alloy elastic reversible diaphragm and preparation method thereof

Abstract

The present invention belongs to the field of titanium alloy forming technology and relates to a titanium alloy elastic reversible diaphragm and a preparation method thereof. The preparation method comprises the following steps: (1) flat plate processing; (2) flat plate heating and heat preservation; (3) variable wall thickness spherical shell blank processing; (4) reversible diaphragm processing. Utilizing the titanium alloy elastic reversible diaphragm and the preparation method thereof of the present invention, a reversible diaphragm can be prepared by processing superelastic titanium alloy, thereby solving the problems of asymmetric deformation and slow reversal response rate during the reversal process of the reversible diaphragm, and making the reversible diaphragm and the aerospace propellant (fuel) tank used therein have better performance, longer service life and lower use cost.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy forming and relates to a titanium alloy elastic reversible diaphragm and a preparation method thereof. Background Art

[0002] As my country's national strength grows, there is an increasingly urgent demand for advanced aviation and aerospace vehicles in both the defense and civilian sectors. Aerospace propellant (fuel) tanks are crucial components of space launch vehicles, serving as storage and management devices for satellites and other spacecraft. Their primary function is to deliver propellant to the engine based on the spacecraft's actual flight conditions, enabling maneuvers such as orbital changes and attitude adjustments. During operation, the diaphragm within the aerospace propellant (fuel) tank undergoes elastic deformation, flipping from the upper hemisphere to the lower hemisphere under the influence of air pressure, thereby discharging the propellant through the tank's outlet. Therefore, the flip diaphragm is a key component of a diaphragm-type tank, and its ability to flip regularly according to predetermined requirements is a key factor in determining tank performance.

[0003] In order to achieve the stable flipping function of the flip diaphragm, it is usually designed as a variable wall thickness structure, that is, the wall thickness is thinner as it is closer to the equator of the spherical shell, and the wall thickness is thicker as it is closer to the spherical crown. This ensures that under air pressure loading, the equator position deforms first and the spherical crown position undergoes plastic deformation last. At the same time, an appropriate wall thickness gradient can increase the stability of the diaphragm during flipping.

[0004] During the production and processing of the tumble diaphragm, the wall thickness must be strictly maintained within the designed dimensions, making the fabrication of metal diaphragms technically challenging. Furthermore, the tumble diaphragm requires significant elastic deformation during operation. Conventional stainless steel and titanium alloys, due to their poor elastic properties and short service life, often wrinkle, become unstable, and tear during the tumble process, seriously impacting the stability of the tank system. Summary of the Invention

[0005] The primary purpose of the present invention is to provide a method for preparing a titanium alloy elastic reversal diaphragm, so that the reversal diaphragm can be prepared by processing superelastic titanium alloy, solving the problems of asymmetric deformation and slow reversal response rate during the reversal process of the reversal diaphragm, so that the prepared reversal diaphragm and the aerospace propellant (fuel) tank used in it have better performance, longer service life and lower use cost.

[0006] To achieve this object, in a basic embodiment, the present invention provides a method for preparing a titanium alloy elastic reversible diaphragm, the method comprising the following steps:

[0007] (1) Flat plate processing: According to the digital model of the plate required for processing the flip diaphragm, the superelastic titanium alloy plate raw material is processed into a flat plate;

[0008] (2) Heating and heat preservation of the flat plate: placing the flat plate on the female mold of the pressing mold under an inert gas environment, heating it and heat-insulating it together with the male mold of the pressing mold;

[0009] (3) Processing of a variable-wall-thickness spherical shell blank: the punch is pressed into the die and held for a period of time so that the flat plate fits tightly into the cavity formed between the die and the punch, thereby forming the variable-wall-thickness spherical shell blank from the flat plate. After cooling, the variable-wall-thickness spherical shell blank is removed from the die;

[0010] (4) Flip diaphragm processing: After the variable wall thickness spherical shell blank is cold-spinned, it is placed in a heat treatment die and a heat treatment punch under an inert gas environment to be heated and kept warm for a certain period of time, and finally the flip diaphragm is formed.

[0011] In a preferred embodiment, the present invention provides a method for preparing a titanium alloy elastic reversible diaphragm, wherein in step (1), finite element analysis is used to perform numerical simulation calculations to determine the numerical model of the plate required for processing the reversible diaphragm.

[0012] In a preferred embodiment, the present invention provides a method for preparing a titanium alloy elastic reversible diaphragm, wherein in step (1), the elastic modulus E≤65GPa and the yield strength 830≤R p0.2 ≤1130Mpa, flexibility index 1.3%≤R p0.2 / E≤2.1%.

[0013] In a preferred embodiment, the present invention provides a method for preparing a titanium alloy elastic reversible diaphragm, wherein in step (2) and step (4), the inert gas environment is a nitrogen and / or argon environment.

[0014] In a preferred embodiment, the present invention provides a method for preparing a titanium alloy elastic reversible diaphragm, wherein in step (2), the heating temperature is 800-900°C, and the insulation treatment time is 30-200 minutes.

[0015] In a preferred embodiment, the present invention provides a method for preparing a titanium alloy elastic reversible diaphragm, wherein in step (3), the holding period is 10-60 minutes.

[0016] In a preferred embodiment, the present invention provides a method for preparing a titanium alloy elastic reversible diaphragm, wherein in step (3), when the convex mold is pressed into the concave mold, the strain rate of the flat piece is 0.001-0.1s -1 .

[0017] In a preferred embodiment, the present invention provides a method for preparing a titanium alloy elastic flip diaphragm, wherein in step (4), the cold spinning is performed on a spinning machine so that the deformation of the variable wall thickness spherical shell blank is 5-20% at the equatorial position and 20-40% at the spherical crown position, and the deformation varies along the latitude gradient of the variable wall thickness spherical shell blank.

[0018] In a preferred embodiment, the present invention provides a method for preparing a titanium alloy elastic reversible diaphragm, wherein in step (4), the heating temperature is 300-350°C, and the insulation time is 10-60 minutes.

[0019] The second purpose of the present invention is to provide a titanium alloy elastic reversal diaphragm to solve the problems of asymmetric deformation and slow reversal response rate during the reversal process of the reversal diaphragm, so that it and the aerospace propellant (fuel) tank used in it have better performance, longer service life and lower use cost.

[0020] To achieve this object, in a basic embodiment, the present invention provides a titanium alloy elastic reversible diaphragm, which is prepared according to the aforementioned preparation method.

[0021] The beneficial effect of the present invention is that, by utilizing the titanium alloy elastic reversal diaphragm and the preparation method thereof of the present invention, the reversal diaphragm can be prepared by processing superelastic titanium alloy, thereby solving the problems of asymmetric deformation and slow reversal response rate during the reversal process of the reversal diaphragm, so that the prepared reversal diaphragm and the aerospace propellant (fuel) tank used therein have better performance, longer service life and lower use cost.

[0022] Compared with the prior art, the advantages of the present invention are:

[0023] (1) Superelastic titanium alloy has a lower elastic modulus, greater rebound ability and stronger fatigue resistance. Using superelastic titanium alloy to prepare the flip diaphragm can greatly increase the service life of the flip diaphragm;

[0024] (2) The work hardening rate varies with the latitude gradient of the hemisphere of the flip diaphragm. The spherical crown of the flip diaphragm has a higher work hardening rate. An appropriate work hardening gradient can further increase the stability of the diaphragm during the flipping process. At the same time, it can reduce the thickness gradient of the flip diaphragm, reduce the thickness of the diaphragm at the spherical crown, reduce the weight of the diaphragm tank, and improve the maneuverability of the system.

[0025] (3) The thermal correction process can significantly improve the dimensional accuracy of the flip diaphragm and increase the product yield, thereby reducing the manufacturing cost of the flip diaphragm. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1The flowchart is an exemplary method for preparing the titanium alloy elastic reversible diaphragm of the present invention.

[0027] Figure 2 Schematic diagram of the placement of the flat part before the punch is pressed into the die.

[0028] Figure 3 This is a schematic diagram of the holding period after the punch is pressed into the die.

[0029] Figure 4 Schematic diagram of the variable wall thickness spherical shell blank obtained by cooling treatment.

[0030] Figure 5 Schematic diagram of the variable wall thickness spherical shell blank after spinning.

[0031] Figure 6 Schematic diagram of the thermal correction process of spherical shell with variable wall thickness.

[0032] Explanation of the accompanying reference numerals: 1. mold punch; 2. flat plate; 3. mold cavity; 4. heat treatment cavity; 5. variable wall thickness spherical shell blank; 6. heat treatment punch. DETAILED DESCRIPTION

[0033] The process of the exemplary method for preparing the titanium alloy elastic reversible diaphragm of the present invention is as follows: Figure 1 As shown, it includes the following steps (the state during the preparation process is as shown Figure 2-6 shown):

[0034] (1) Using superelastic titanium alloy sheet as raw material, finite element analysis is used to perform numerical simulation calculations to determine the numerical model of the sheet required for processing the flip diaphragm;

[0035] (2) machining the superelastic titanium alloy sheet into a flat plate according to the digital model;

[0036] (3) placing the flat plate on the concave die of the compression mold under an inert gas environment, heating it, and performing heat preservation treatment together with the convex die of the compression mold;

[0037] (4) The punch of the die is pressed into the die of the die and held for a period of time, and the superplasticity of the superelastic titanium alloy is utilized to make the flat plate fit tightly with the cavity of the die, thereby forming a spherical shell blank with a variable wall thickness.

[0038] (5) cooling the molding die and the variable-wall-thickness spherical shell blank, and taking out the variable-wall-thickness spherical shell blank;

[0039] (6) The variable wall thickness spherical shell blank is cold-spinned on a spinning machine to give it a certain work hardening gradient and processed into the final product shape;

[0040] (7) In an inert gas environment, the variable wall thickness spherical shell blank is placed in a heat treatment die and a heat treatment punch for heating and keeping warm for a certain period of time (thermal correction). This can eliminate some residual stress on the one hand, and correct the flip diaphragm on the other hand to improve its dimensional accuracy.

[0041] in:

[0042] In step (1), the elastic modulus E≤65GPa and the yield strength 830≤R p0.2 ≤1130Mpa, flexibility index 1.3%≤R p0.2 / E≤2.1%.

[0043] In step (3) and step (7), the inert gas environment is a nitrogen and / or argon environment.

[0044] In step (3), the heating temperature is 800-900° C., and the insulation treatment time is 30-200 min.

[0045] In step (4), the period of time is 10-60 minutes.

[0046] In step (4), when the punch is pressed into the die, the strain rate of the flat piece is 0.001-0.1s -1 .

[0047] In step (6), the cold spinning forming causes the variable wall thickness spherical shell blank to be deformed by 5-20% (thinning) at the equator position and 20-40% (thinning) at the spherical crown position, and the deformation varies along the latitude gradient of the variable wall thickness spherical shell blank.

[0048] In step (7), the heating temperature is 300-350° C., and the insulation time is 10-60 minutes.

[0049] The application examples of the above exemplary method for preparing the titanium alloy elastic reversible diaphragm of the present invention are as follows.

[0050] Example 1:

[0051] Ti-35% Nb-2% Zr-0.3% O (mass fraction) titanium alloy plate (Chinese patent CN104962777B discloses the composition and preparation method, Rp 0.2 =1029MPa, elastic modulus E=57GPa, flexibility index Rp 0.2 / E=1.8%) as raw material, numerical simulation is used to determine the digital model of the slab required for processing the flip diaphragm; the superelastic titanium alloy plate is machined into a flat plate according to the digital model by machining technology; the flat plate is placed on the die under argon environment and heated to 850℃ and kept at 850℃ for 120min together with the punch; the punch is pressed into the die at a rate of 10mm / min (strain rate 0.001s -1 ), and hold for 20 minutes; after cooling, take out the superelastic titanium alloy variable-wall thickness spherical shell blank, and the shell thickness gradient is 1.0 mm to 1.5 mm; the superelastic titanium alloy variable-wall thickness spherical shell blank is cold-spun on a spinning machine into the final product shape (the cold spinning deformation from the spherical crown to the equator is gradually reduced from 26% to 10%); in an argon environment, the superelastic titanium alloy variable-wall thickness spherical shell blank is placed in a heat treatment die and a punch, and heated to 350° C. and kept warm for 30 minutes, on the one hand to eliminate some residual stress, and on the other hand to correct the flip diaphragm, and finally a finished flip diaphragm is obtained, whose inner diameter is 216 mm and the thickness gradient is 0.9 mm to 1.1 mm.

[0052] Example 2:

[0053] Ti-37% Nb-0.3% O (mass fraction) titanium alloy plate (Chinese patent CN104962777B discloses the composition and preparation method, Rp 0.2 =988MPa, elastic modulus E = 58GPa, flexibility index R p0.2 / E=1.7%) as raw material, numerical simulation is used to determine the digital model of the slab required for processing the flip diaphragm; the superelastic titanium alloy plate is machined into a flat piece according to the digital model by machining technology; the flat piece is placed on the die under argon environment and heated to 900℃ and kept at 900℃ for 180min together with the punch; the punch is pressed into the die at a rate of 60mm / min (strain rate 0.005s -1 ), and hold for 30 minutes; after cooling, take out the superelastic titanium alloy variable-wall thickness spherical shell blank, and the shell thickness gradient is 1.1mm~2.0mm; the superelastic titanium alloy variable-wall thickness spherical shell blank is cold-spun on a spinning machine into the final product shape (the cold spinning deformation from the spherical crown to the equator is gradually reduced from 25% to 10%); in an argon environment, the superelastic titanium alloy variable-wall thickness spherical shell blank is placed in a heat treatment die and a punch, and heated to 350°C and kept warm for 40 minutes, on the one hand to eliminate some residual stress, and on the other hand to correct the flip diaphragm, and finally a finished flip diaphragm is obtained, whose inner diameter is 278mm and the thickness gradient is 1mm~1.5mm.

[0054] Comparative Example 1:

[0055] Pure titanium plate (R p0.2 =322Mpa, elastic modulus E = 107GPa, flexibility index Rp0.2 / E=0.3%) as the raw material, and other aspects were the same as in Example 1, and finally a finished product of the inverted diaphragm was obtained, which had an inner diameter of 216 mm and a thickness gradient of 0.9 mm to 1.1 mm.

[0056] Comparative Example 2:

[0057] Ti-6Al-4V titanium alloy plate (R p0.2 =898Mpa, elastic modulus E = 110GPa, flexibility index R p0.2 / E=0.8%) as the raw material, and the other aspects were the same as those in Example 2, and finally a finished product of the inverted diaphragm was obtained, which had an inner diameter of 278 mm and a thickness gradient of 1 mm to 1.5 mm.

[0058] Example 3:

[0059] The following performance tests were performed on the flip diaphragms prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2: 1) A latitude line was drawn on the flip diaphragm from the equator to the spherical cap every 10°, for a total of 9 lines. The thickness t of the flip diaphragm on each latitude line was measured. 20 points were measured on each latitude line to determine the thickness t of each strip. max -t min 2) The diaphragm was flipped under pressure differentials of 0.15 MPa to 0.25 MPa and 0.25 MPa to 0.5 MPa, respectively, and the propellant discharge rate was calculated. The results are shown in Tables 1 and 2 below.

[0060] Table 1 Test results of flip diaphragm performance

[0061]

[0062] As shown in Table 1, the titanium alloy elastic reversible diaphragms prepared in Examples 1 and 2 of the present invention have significantly better thickness uniformity than those prepared in Comparative Examples 1 and 2. Furthermore, the propellant discharge rates of the titanium alloy elastic reversible diaphragms prepared in Examples 1 and 2 of the present invention are significantly higher than those prepared in Comparative Examples 1 and 2. Therefore, the performance of the reversible diaphragms prepared in the present invention has been significantly improved.

[0063] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these changes and variations. The above embodiments or implementation methods are merely illustrative of the present invention, and the present invention may also be implemented in other specific ways or other specific forms without departing from the gist or essential features of the present invention. Therefore, the described implementation methods should be regarded as illustrative and not restrictive in any respect. The scope of the present invention should be described by the appended claims, and any changes that are equivalent to the intent and scope of the claims should also be included within the scope of the present invention.

Claims

1. A method for preparing a titanium alloy elastic reversible diaphragm, characterized in that: The preparation method comprises the following steps: (1) Flat plate processing: According to the digital model of the plate required for processing the flip diaphragm, the superelastic titanium alloy plate raw material is processed into a flat plate; (2) Heating and heat preservation of the flat plate: placing the flat plate on the female mold of the pressing mold under an inert gas environment, heating it and heat-insulating it together with the male mold of the pressing mold; (3) Processing of a variable-wall-thickness spherical shell blank: the punch is pressed into the die and held for a period of time so that the flat plate fits tightly into the cavity formed between the die and the punch, thereby forming the variable-wall-thickness spherical shell blank from the flat plate. After cooling, the variable-wall-thickness spherical shell blank is removed from the die; (4) Flip diaphragm processing: After the variable wall thickness spherical shell blank is cold-spinned, it is placed in a heat treatment die and a heat treatment punch under an inert gas environment to be heated and kept warm for a certain period of time, and finally the flip diaphragm is formed. in: In step (1), the elastic modulus E≤65GPa and the yield strength 830≤R p0.2 ≤1130Mpa, flexibility index 1.3%≤R p0.2 / E≤2.1%; In step (4), the cold spinning is performed on a spinning machine so that the deformation of the variable wall thickness spherical shell blank is 5-20% at the equator position and 20-40% at the spherical crown position, and the deformation varies along the latitude gradient of the variable wall thickness spherical shell blank.

2. The preparation method according to claim 1, wherein: In step (1), finite element analysis is used to perform numerical simulation calculations to determine the numerical model of the plate required for processing the flip diaphragm.

3. The preparation method according to claim 1, wherein: In step (2) and step (4), the inert gas environment is a nitrogen and / or argon environment.

4. The preparation method according to claim 1, wherein: In step (2), the heating temperature is 800-900° C., and the insulation treatment time is 30-200 min.

5. The preparation method according to claim 1, wherein: In step (3), the holding period is 10-60 minutes.

6. The preparation method according to claim 1, wherein: In step (3), when the punch is pressed into the die, the strain rate of the flat plate is 0.001-0.1s -1 .

7. The preparation method according to claim 1, wherein: In step (4), the heating temperature is 300-350° C., and the insulation time is 10-60 minutes.

8. A titanium alloy elastic reversible diaphragm, characterized by: The inverted membrane is prepared by the preparation method according to any one of claims 1-7.

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