Special-shaped corrugated heat shield, die and forming method for a swinging spray pipe

Abstract

The present invention discloses a special-shaped corrugated heat shield for a swing nozzle, a mold and a forming method. The special-shaped corrugated heat shield sequentially includes an inclined section, a vertical section and a corrugated section from top to bottom. The upper end point of the end of the flexible joint abuts against the vertical section, and the lower end point abuts against the bottom end of the corrugated section. The inclined section wraps the end of the flexible joint. It solves the negative moment generated by the heat shield during the swing of the nozzle, reduces the use of protective putty, thereby reducing the negative weight of the nozzle and the problem of die pressing of the special-shaped corrugated heat shield, and realizes the one-time forming of the special-shaped corrugated heat shield.

Description

Technical Field

[0001] The invention belongs to the technical field of swing nozzle parts for solid rocket engines, and in particular relates to a special-shaped corrugated heat-proof sleeve, a mold and a molding method for the swing nozzle. Background Art

[0002] The flexible nozzle of a solid rocket engine is a good full-axis swing nozzle. The flexible nozzle has a series of advantages such as small thrust loss, stable performance, reliable sealing, and the ability to be submerged in the combustion chamber. The core of the flexible swing nozzle is the flexible joint. The elastic part of the flexible joint is mainly composed of rubber materials. The rubber material can only work within a certain temperature range. The flexible joint reinforcement is usually made of metal parts. The thermal conductivity of metal parts is relatively high. Therefore, thermal protection is required on the side close to the gas to protect the flexible joint. Usually, a heat-proof sleeve is used for thermal protection of the flexible joint.

[0003] The design principles of the heat shield are generally as follows: the unfolded length of the heat shield when the nozzle swings can meet the elongation requirement of the maximum swing angle of the nozzle; the use of flexible materials allows the nozzle to extend freely when it swings, and the torque of the heat shield is low; the heat shield can be opened during installation to ensure the balance of air pressure inside and outside the heat shield when the nozzle is working; the gap between the heat shield and the flexible joint is filled with non-vulcanized sealing putty to prevent ablation; the thickness of the heat shield is determined according to the engine working time and the anti-ablation and anti-erosion properties of the heat shield.

[0004] In view of the working conditions and characteristics of the heat shield, EPDM rubber is currently used as the raw material to make the heat shield. Usually, the heat shield is designed to ensure that the surface is as simple as possible. Figure 1 As shown, it is convenient for loading and demoulding. When the nozzle swings, the elongation of the swing angle is guaranteed by the elongation of the rubber itself, but the elongation of the rubber is required to be relatively high, and at the same time, the swing torque of the nozzle is increased to a certain extent. Summary of the invention

[0005] In view of the defects of the above-mentioned technology, the present invention provides a special-shaped corrugated heat-proof sleeve, a mold and a molding method which can reduce the stress on the heat-proof sleeve itself and further reduce the swing torque of the nozzle.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a special-shaped corrugated heat-proof sleeve for a swinging nozzle, which comprises an inclined section, a vertical section and a corrugated section from top to bottom, the upper end point of the end of the flexible joint abuts against the vertical section, the lower end point abuts against the bottom end of the corrugated section, and the inclined section wraps the end of the flexible joint; the length of the corrugated section L≥H / COSθ-H, H is the height of the flexible joint, and θ is the maximum swing angle of the nozzle.

[0007] Furthermore, the corrugated section is a corrugated section, and the corners at both ends are 30° to 45° and 45° to 60° respectively.

[0008] Further, the wall thickness δ of the special-shaped corrugated heat shield is δ = R L × T × n, and it has a uniform wall thickness. R L is the oxyacetylene line ablation rate, T is the working time of the nozzle, and n is the safety factor.

[0009] There is also provided a compression molding die for manufacturing the special-shaped corrugated heat shield for the swing nozzle, which includes a punch assembly, a die, a compression sleeve, and a mold clamping ring. The profile of the die matches the outer profile of the special-shaped corrugated heat shield, and connecting screws connect the punch assembly and the die; the compression sleeve is internally supported at the upper end of the punch assembly, and the mold clamping ring is placed between the die and the punch assembly.

[0010] Further, the punch assembly is a split punch, including two first punches and two second punches, and the two first punches and the two second punches are symmetrically and alternately arranged; the die adopts an integral die.

[0011] Finally, there is also provided a forming method for the special-shaped corrugated heat shield for the swing nozzle. The special-shaped corrugated heat shield is formed by using the above-mentioned compression molding die. The specific process is as follows: Place the EPDM rubber strip closely against the lower part of the die in sequence until the corrugated section; Connect the punch assembly and the die with connecting screws, and after applying a pre-tightening force to the connecting screws, place the compression sleeve; Transfer it to a press, apply pressure, and then use the connecting screws to further tighten the die and the punch assembly, and at the same time compact the bottom rubber material; Cut the rubber strip into small rubber strips and fill them into the mold cavity. After each addition of small rubber strips, use the mold clamping ring to compact the rubber material, and heat and vulcanize on a vulcanizer to obtain the product.

[0012] Compared with the prior art, the advantages of the present invention are as follows: The special-shaped corrugated heat shield, die, and forming method for the swing nozzle of the present invention solve the negative torque generated by the heat shield during the swing of the nozzle, and at the same time reduce the use of protective putty, thereby reducing the negative weight of the nozzle and the problem of the special-shaped corrugated heat shield tooling compression molding, and realizing the one-time forming of the special-shaped corrugated heat shield. Description of the Drawings

[0013] Figure 1 It is a schematic diagram of the existing heat shield structure;

[0014] Figure 2 It is an assembly schematic diagram of the special-shaped corrugated heat shield of the present invention;

[0015] Figure 3 It is for Figure 2 the schematic diagram of the structure of the special-shaped corrugated heat shield;

[0016] Figure 4 It is a schematic diagram of the compression molding die structure. Detailed Embodiments

[0017] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0018] As Figure 2 shown, the wall thickness δ of the special-shaped corrugated heat shield 2 is δ = R L ×T×n, where R L is the oxyacetylene line ablation rate, T is the nozzle working time, and n is the safety factor; to ensure a relatively simple profile, an equal wall thickness design is adopted.

[0019] As Figure 3 shown, the special-shaped corrugated heat shield 2 successively includes an inclined section 3, a vertical section 4, and a corrugated section 5 from top to bottom. The upper endpoint of the end of the flexible joint 1 abuts against the vertical section 4, and the lower endpoint abuts against the bottom end of the corrugated section 5. The inclined section 3 wraps the end of the flexible joint 1. The length of the corrugated section ≥ the elongation of the rubber when the nozzle has the maximum swing angle, that is, the length of the corrugated section (rubber elongation) L ≥ H / COSθ - H, where H is the height of the flexible joint and θ is the maximum swing angle of the nozzle; since the swing angle of the nozzle is generally small, to ensure a simple profile, a single corrugation design is adopted, and the two end corners are 30° - 45° and 45° - 60° respectively.

[0020] The special-shaped corrugated heat shield 1 is formed by compression molding. As Figure 4 shown, the compression molding die includes a split punch assembly 6, a die 8, a compression sleeve 9, and a die closing ring 7. The punch assembly 6 is a split punch, including two first punches and two second punches. The two first punches and the two second punches are arranged symmetrically and alternately. The split punch ensures the corrugated profile of the heat shield and facilitates the demolding of the corrugated section of the heat shield, avoiding damage during demolding; the die 8 adopts an integrated design, and the profile of the die 8 matches the outer profile of the special-shaped corrugated heat shield 1 to ensure the outer profile dimensions of the heat shield. At the same time, it serves as the positioning surface for the split punch and is used for connection and fixation with the split punch. The connecting screw 10 connects the split punch and the die 8; the compression sleeve 9 is internally supported at the upper end of the split punch to ensure that the inner profile of the split punch is on the same circle; the die closing ring 7 is placed between the die 8 and the split punch. The die closing ring 7 limits the pitch circle of the outer profile of the punch assembly 6 to ensure that the punch assembly 6 is in the same state as before splitting. The die closing ring 7 serves as an auxiliary tool for feeding, extruding the rubber material into the compression molding die, and at the same time ensuring the upper profile of the heat shield.

[0021] When forming the special-shaped corrugated heat shield, clean the mold, place the EPDM rubber strips closely against the lower part of the concave mold in sequence until the corrugated section; use connecting screws to connect the split punch and the concave mold, and place the compression sleeve after applying the pre-tightening force to the connecting screws to ensure that the inner surface of the punch is on the same circle; transfer it to the press, apply pressure and then use the connecting screws to further tighten the connecting screws of the concave mold and the punch, and at the same time compact the bottom rubber material. Cut the rubber strips into small rubber strips and fill them into the mold cavity. After each addition of small rubber strips, use the die closing ring to compact the rubber material, and heat and vulcanize on the vulcanizer to obtain the product. The specific vulcanization process is as follows: cold press (1-2 MPa) 3 times and then relieve the pressure, raise the temperature to (90±5) °C and keep it warm for 30 min, exhaust 3 times and then pressurize to 10 MPa, continue to raise the temperature to (120±5) °C and exhaust 2 times, maintain the pressure at 10 MPa, continue to raise the temperature to (155±5) °C, keep it warm for 90 min - 92 min, and then cut off the power and cool down to room temperature to take out the mold.

[0022] Using this mold, the production of the special-shaped corrugated heat shield can be realized. The heat shield molded by die pressing has a certain adaptability to the flexible joint. When the nozzle swings, the elongation of the heat shield is ensured through the corrugated structure and the performance of the rubber itself, reducing the force on the heat shield itself, further reducing the swing torque of the nozzle, and at the same time reducing the cavity between the heat shield and the flexible joint, further reducing the filling of the non-vulcanized putty. The total weight of the used thermal protection putty is reduced by 1.7%, reducing the negative weight of the nozzle. The special-shaped corrugated heat shield, mold and forming method for the swinging nozzle of the present invention solve the negative torque generated by the heat shield during the swing of the nozzle, and at the same time reduce the use of the protective putty, thereby reducing the negative weight of the nozzle and the problem of die pressing of the special-shaped corrugated heat shield tooling, and realizing the one-time forming of the special-shaped corrugated heat shield.

Claims

1. A special-shaped corrugated heat shield for a swing nozzle, characterized in that: The special-shaped corrugated heat shield (2) successively includes an inclined section (3), a vertical section (4) and a corrugated section (5) from top to bottom. The upper end point of the end of the flexible joint (1) abuts against the vertical section (4), and the lower end point abuts against the bottom end of the corrugated section (5). The inclined section (3) wraps the end of the flexible joint (1); the length L of the corrugated section is ≥ H / COSθ – H, where H is the height of the flexible joint and θ is the maximum swing angle of the nozzle.

2. The special-shaped corrugated heat shield for a swing nozzle according to claim 1, characterized in that: The corrugated section (5) is a single corrugated section, and the two end corners are 30° - 45° and 45° - 60° respectively.

3. The special-shaped corrugated heat shield for a swing nozzle according to claim 1, characterized in that: The wall thickness δ of the special-shaped corrugated heat shield (2) is δ = R L ×T×n, and it has a uniform wall thickness. R L is the oxyacetylene line ablation rate, T is the nozzle working time, and n is the safety factor.

4. A molding die for manufacturing the special-shaped corrugated heat shield for a swing nozzle according to claim 1, characterized in that: It includes a punch assembly (6), a die (8), a compression sleeve (9) and a die closing ring (7). The profile of the die (8) matches the outer profile of the special-shaped corrugated heat shield (2). Connecting screws (10) connect the punch assembly (6) and the die (8); the compression sleeve (9) is internally supported on the upper end of the punch assembly (6), and the die closing ring (7) is placed between the die (8) and the punch assembly (6).

5. The molding die for the special-shaped corrugated heat shield for a swing nozzle according to claim 4, characterized in that: The punch assembly (6) is a split punch, including two first punches and two second punches. The two first punches and the two second punches are symmetrically and alternately arranged; the die (8) is an integral die.

6. A forming method for the special-shaped corrugated heat shield for a swing nozzle, characterized in that: The special-shaped corrugated heat shield is formed by using the molding die as claimed in claim 4. The specific process is as follows: Place the ethylene propylene diene monomer rubber strip closely against the lower part of the die in sequence until the corrugated section; Connect the punch assembly and the die with connecting screws. After applying a pre-tightening force to the connecting screws, place the compression sleeve; Transfer it to a press, apply pressure and then use the connecting screws to further fasten the die and the punch assembly, and at the same time compact the bottom rubber material; Cut the rubber strip into small rubber strips and fill them into the mold cavity. After each addition of small rubber strips, use the die closing ring to compact the rubber material, and heat and vulcanize on a vulcanizer to obtain the product.

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