Device and method for manufacturing ultrasonically enhanced head cap wound to reinforce engine casing

Abstract

The present invention belongs to the field of engine casing preparation, and specifically relates to an ultrasonically enhanced head cap winding and reinforcement engine casing manufacturing device and method. It includes multiple metal split molds, a core shaft, an ultrasonic vibration head device and a positioning skeleton; a through hole is opened in the middle of the core shaft, and the through hole is for the line of the ultrasonic vibration head device to pass through. The core shaft is located inside the engine casing barrel section at the corresponding positions at both ends and is detachably connected with a positioning skeleton, which is used to position the split mold. Multiple metal split molds are combined to form a barrel, and an ultrasonic vibration head device is provided inside each split mold. The method of the present invention improves the airtightness, uniformity and structural strength of the casing barrel section and the head section by winding and reinforcing the head cap, and then combines the metal detachable core mold with the ultrasonic enhancement device to reduce the porosity, thereby improving the performance and reliability of the rocket engine.

Description

Technical Field

[0001] The present invention belongs to the field of engine casing preparation, and in particular relates to a device and method for manufacturing an engine casing by winding a head cap for ultrasonic enhancement. Background Art

[0002] Carbon fiber composite rocket engine casings are typically manufactured using a monolithic winding process, where pre-impregnated carbon fiber is wound around a core mold. While this process can achieve constant stress in the barrel section, stress concentration occurs at the end section due to large variations in structural stiffness and uneven thickness distribution. Furthermore, carbon fiber reinforced composites are brittle and sensitive to structural discontinuities. Consequently, ensuring the sealing and structural integrity of the end section is often difficult, limiting the performance and reliability of the rocket engine.

[0003] Compared to traditional winding processes for forming engine casings, winding the head cap can effectively simplify the winding process, improve the sealing and structural integrity of the head section, reduce stress concentration, and thus enhance the performance and reliability of the rocket engine. However, problems such as residual bubbles exist in the connection area between the head cap and the barrel section, resulting in poor strength and airtightness in the connection area. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for manufacturing a rocket engine casing reinforced by winding an ultrasonically enhanced head cap.

[0005] The technical solution to achieve the purpose of the present invention is: an ultrasonic enhanced head cap winding reinforcement engine casing manufacturing device, comprising a plurality of metal split molds, a core shaft, an ultrasonic vibration head device and a positioning frame;

[0006] A through hole is opened in the middle of the core shaft for the line of the ultrasonic vibration head device to pass through. The core shaft is located at the corresponding positions at both ends of the engine casing barrel section, and the positioning skeleton is detachably connected. The positioning skeleton is used to position the split mold. Multiple metal split molds are combined to form a cylinder body, and each split mold has an ultrasonic vibration head device inside.

[0007] Furthermore, the ultrasonic vibration head device includes an ultrasonic transducer, a horn, a vibration rod and a rubber head;

[0008] The vibrating rod is in the shape of an aluminum pen tip, the tip of the vibrating rod is a rubber head, and the ultrasonic vibrating head device is connected to the petal mold by strong glue.

[0009] Furthermore, the core mold skeleton includes an annular portion that contacts the inner wall of the split mold, and the annular portion is connected through a skeleton and a core shaft screw that are evenly arranged circumferentially; a dovetail-shaped protrusion is provided on the split mold, and the annular portion of the core mold skeleton is provided with an interlocking groove that matches the protrusion.

[0010] A method for manufacturing a rocket engine casing using the above-mentioned device comprises the following steps:

[0011] Step (1): assembling the device;

[0012] Step (2): Winding is performed on a core mold formed by a plurality of split molds: the barrel section is first wound spirally and then wound circumferentially, and the head sections on both sides of the barrel section are wound circumferentially in a stepped manner to form a stepped shape with decreasing height from the barrel section to the head section;

[0013] Step (3): Adding a head cap: The head cap is preformed and made of the same material as the engine casing. The shape of the head cap is an ellipsoid with equal thickness. The head cap is added to fill the height difference between the barrel section and the head section, and then the entire casing is spirally wound;

[0014] Step (4): After the winding is completed, the shell is placed in a curing chamber for vacuum treatment. After a part of the bubbles are discharged, the ultrasonic vibration head device on the inner wall of the core mold is controlled to adjust the frequency, power, amplitude and action time of the ultrasonic wave to effectively remove the bubbles inside the shell;

[0015] Step (5): Place the shell in a curing chamber and ensure the curing quality of the shell material by controlling the temperature, time and rotation speed.

[0016] Furthermore, the thickness of the spiral winding layer of the barrel section in step (2) is 2.5 mm, and the thickness of the circumferential winding layer is 2.2 mm; and the barrel section ply laying sequence is the optimal ply laying sequence of {[(15.1°), (-15.1°), (15.1°)], (90°)2}, 3 spiral winding layers and 2 circumferential winding layers; after the circumferential winding is completed, there will be a height difference of 2.2 mm between the head section and the barrel section; during the winding process, each layer is coated with glue to form a reinforcement layer.

[0017] Furthermore, in step (3), the angle of the spiral winding is [(15.1°), (-15.1°)], the winding layer is 2 layers, and the winding thickness is 1.7 mm; during the winding process, each layer is coated with glue to form a reinforcement layer.

[0018] Furthermore, a dry winding process is adopted in both steps (1) and (3), the T70012K unidirectional fiber bundle is unfolded, the prepreg tape is released from the reel and directly wound on the core mold installed on the winding machine tooling, the prepreg speed is set to 0.5 m / min, the constant tension is set to 2.5 N, and the temperature is set to 80-130°C.

[0019] Furthermore, step (4) is specifically as follows:

[0020] After winding, place it in the curing chamber, evacuate the curing chamber, and control the pressure at 0.05MPa to 0.1MPa;

[0021] Turn on the ultrasonic vibration head device, control the ultrasonic frequency to 20kHz to 40kHz, the power to 300W to 600W, the amplitude to 20μm to 40μm, and the action time to 5 minutes to 8 minutes; and perform two to three cycles.

[0022] Furthermore, the specific parameters of the curing process in step (5) are as follows: heating from room temperature to 90°C to 120°C at a heating rate of 25°C to 30°C / h, maintaining the temperature for 2 to 4 hours, and naturally cooling to room temperature after the curing is completed; and maintaining the composite material shell at a uniform rotation speed of 2 r / min during the curing process;

[0023] After curing is completed, let it stand for 5 to 10 minutes, then remove the shell and dismantle the core mold device;

[0024] Remove the two pairs of nuts on the core shaft that are used to fix the joint plates at both ends, and then remove the joint plates; remove the positioning frame, and after removing the positioning frame, remove the petal mold, pull out the core shaft, and complete the removal of the core mold.

[0025] A rocket engine casing is manufactured using the above method, and the casing material is a carbon fiber resin composite material.

[0026] Compared with the prior art, the present invention has the following significant advantages:

[0027] (1) Uniform strength distribution and lightweight: Compared with the circumferential spiral alternating winding in the traditional technology, the present invention adopts the method of step winding and head cap for the thin wall at the transition between the barrel and the head, thus avoiding the stress concentration problems existing at the critical point of circumferential winding and spiral winding. In addition, the spiral-circumferential fiber winding process is adopted at the step, and the number of linear alternations is reduced, and the stress on the composite layer is reduced. After adding the head cap, the overall spiral winding is adopted to make the connection more stable, the head section can withstand greater pressure, and the blasting pressure of the shell as a whole is effectively improved. Under this winding method of the present invention, the blasting pressure of the shell is increased from 18MPa to 21Mpa; the improvement effect is about 16%, which is quite significant; and at the same time, compared with the basic sample molding method, the weight is reduced by 14.1%, which helps to achieve the lightweighting of the rocket engine shell.

[0028] (2) High airtightness: The present invention uses vacuum treatment and ultrasonic degassing technology to effectively reduce the porosity at the connection between the head cap and the barrel section and effectively remove interlayer bubbles. This reduces the porosity of the composite shell to less than 1%, improving the reliability and durability of the shell.

[0029] (3) High material utilization and flexible protection of the ultrasonic head: The core mold structure is made of metal, which has the characteristics of easy disassembly and assembly, high positioning accuracy, long service life and low production cost. In addition, the ultrasonic vibration tool head is designed into a pen tip shape and rubberized to minimize the mechanical damage to the shell and core mold itself caused by the ultrasonic high-frequency vibration. Reasonable layer design also reduces the winding cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of the split-petal metal core mold with an ultrasonic device in the present invention; (a) is an overall schematic diagram, (b) is a side sectional view, and (c) is a partial ultrasonic schematic diagram.

[0031] Figure 2 This is a schematic diagram of the ultrasonic vibration tool head device of the present invention.

[0032] Figure 3 Schematic diagram of the method of the present invention; (a) is a schematic diagram of dry winding; (b) is a schematic diagram of the barrel winding and head cap reinforcement winding of the present invention; (c) is a diagram of the ultrasonic degassing effect.

[0033] Description of reference numerals:

[0034] 1-line, 2-core shaft, 3-ultrasonic vibration head device, 4-fitting groove, 5-nut, 6-connector plate, 7-petal mold, 8-positioning skeleton, 2-1-ultrasonic transducer, 2-2-amplifier, 2-3-vibration rod, 2-4-rubber head, 3-1-inner spiral winding section, 3-2-circumferential winding section, 3-3-outer spiral winding section, 3-4-head cap, 3-5-connector. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below with reference to the accompanying drawings.

[0036] The metal detachable core mold adopts a modular split mold design, which includes a positioning skeleton 8, a core mold split mold 7, a punched core shaft 2, an ultrasonic vibration head device 3 and an ultrasonic transducer 2-1. The outer curved surface of the core mold split mold 7 is divided into multiple mold flaps along the circumferential direction. The split mold 7 is composed of six groups, one of which is a small component, which is convenient for the disassembly and assembly of the core mold split mold. And it is engaged with the positioning skeleton 8 through the interlocking groove 4 reserved on the skeleton to ensure that the position of the split mold 7 on the skeleton is accurately fixed. The ultrasonic vibration head tool is installed on the inner wall of the split mold 7 by gluing with strong glue, and the debubbling effect is optimized by adjusting the amplitude, frequency and time. The core shaft 2 of the core mold is punched to connect the required lines of the vibration tool head.

[0037] The positioning frame 8 is composed of six frames distributed radially along the circular hole. Each frame has a recessed slot near the top for connecting with the split mold. The split mold is assembled and disassembled by sliding through the protrusions and recessed slots. The positioning frame is assembled and disassembled using bolts, nuts, and a mandrel.

[0038] A modular ultrasonically enhanced and head cap winding reinforced rocket engine casing manufacturing process method comprises the following steps:

[0039] Step 1)

[0040] The core mold structure is integrated with the ultrasonic vibration head tool: Figure 1 As shown in (b), the split mold 7 is composed of six groups, including Figure 1 Each split mold on the barrel section shown in (c) is equipped with an ultrasonic vibration tool head device. These vibration tool heads are glued to the inner side of the split mold by strong glue in the middle of the thin slice of the core mold split mold 7. The two ends of each split mold are connected to the core mold positioning frame 8 by a Figure 1 The grooves marked with 4 in (a) are fitted together to ensure structural stability.

[0041] At the same time, the core shaft 2 of the core mold is a key component that connects to the positioning frame 8 and plays a supporting role. In order to realize the power connection of the ultrasonic device, a through hole is designed on the core shaft 2. These holes are used to receive the required connection lines of the ultrasonic device. The ultrasonic transducer 2-1 and the vibration tool head are as follows. Figure 2 The circuit is connected to a transducer, which converts the electrical signal into a mechanical vibration signal, which is then transmitted to the vibrating tool head to form ultrasonic vibration. The amplitude is adjusted by amplitude adjustment, and then transmitted to the composite material shell by the vibrating petal mold 7 of the rubber head 2-4.

[0042] According to the principle of ultrasonic vibration, the vibrations generated by the ultrasonic vibrator propagate through the board material. This vibration can propagate throughout the entire board structure, not just in the area directly in contact with the ultrasonic vibrator. Therefore, as shown in the figure, precisely positioning the ultrasonic device in the center of the split mold ensures that the vibration energy is effectively and symmetrically transmitted to the composite material wrapping area. The microjets and shock waves generated by the cavitation effect of ultrasonic vibration can shatter or remove bubbles in the voids to a point where they do not affect product performance. This is particularly helpful in removing bubbles from the voids in the wrapping of the head cap and barrel sections.

[0043] During the installation and disassembly of the core mold, the modular design ensures that the ultrasonic device and connecting lines can be easily installed and maintained during the disassembly of the core mold.

[0044] Step 2) Filament Winding Process

[0045] The present invention adopts dry winding process, uses special fiber spreading equipment to unfold T70012K unidirectional fiber bundle, releases the prepreg from the reel and directly winds it on the core mold installed on the winding machine tool, and the prepreg speed is set to 0.5m / min. Figure 3 As shown in (a), the tension control and heating device is set to a constant tension of 2.5N and a temperature of 80-130°C. This tension is applied to the fiber bundle during the winding process to ensure that the fiber bundle is evenly impregnated with resin and tightly wound around the core. The nozzle controls the orientation of the carbon fiber tape, ensuring precision and consistency during the winding process.

[0046] Spiral winding is a composite manufacturing technique in which prepreg is wound at an angle (less than 90 degrees) relative to the axis of the mandrel, forming a spiral fiber path. During the winding process, the winding head moves over the mandrel, releasing prepreg and wrapping it around the mandrel, with each layer forming a certain angle with the fiber direction of the previous layer.

[0047] Hoop winding involves winding the fiber along the axis of the core mold, forming a circular fiber path. During the hoop winding process, the winding head moves in a circular path on the core mold, releasing the prepreg and evenly wrapping it around the core mold.

[0048] For the rocket engine shell, in the first winding stage on the barrel section, the spiral layer is wound starting from the pole hole, and then the second stage of circumferential winding is carried out on it. The height difference of the circumferential fiber layer at the transition point between the symmetrical structure of the barrel section and the head is T C On the one hand, the strength of the barrel section after winding is equal to or greater than that of the traditional winding method, and on the other hand, the contact thickness is increased by T C The head cap can be fitted to reduce the gap between the head and the barrel during the production process, and then the whole is spirally wound again to reinforce the contact section and the shell itself, thereby enhancing the mechanical properties of the shell. Figure 3 shown.

[0049] The rocket engine case safety failure explosion location is in the barrel section. Hoop winding primarily provides circumferential radial stress, while spiral winding provides axial force to protect the head. Therefore, the layers can be laid in this order: inner spiral winding followed by outer spiral winding. At the same time, the overall outer spiral winding can further stabilize the overall structure of the head cap and the case.

[0050] The winding process of the rocket engine shell includes the accurately calculated circumferential winding and spiral winding, and the winding angle calculation: according to the isopolar hole structure and the geodesic winding formula The calculation results in α = 15.1°, where r0 is the polar aperture radius and r is the radius of the circle at any latitude;

[0051] Using improved grid theory, we calculated the thickness of the helical wrap layer in the barrel section to be 2.5 mm and the thickness of the hoop wrap layer to be 2.2 mm. Using MATLAB software combined with cubic spline function and geometric methods, we determined the optimal layup sequence of two helical wrap layers and two hoop wrap layers.

[0052] Finite element simulations determined a layup sequence of {[(15.1°), (-15.1°), (15.1°)], (90°)²} for the barrel section. A 2.2mm thick head was added, followed by an overall spiral wrap reinforcement strategy. The spiral wrap angle was 40°, with two wrap layers and a wrap thickness of 1.7mm.

[0053] The shell burst pressure under this winding method is increased from 18MPa to 21MPa, which is a significant improvement of about 16%.

[0054] In addition, the use of the head cap and this winding method reduces the weight by 14.1% compared to the basic sample molding method.

[0055] During hoop winding, the constant tension is set to 2.5 N. This is the tension applied to the fiber bundle during the winding process to ensure that the fiber bundle can be evenly impregnated with resin and tightly wound around the core mold.

[0056] Step 3) Ultrasonic bubble removal after vacuuming

[0057] After the winding is completed, it is placed in the curing chamber for subsequent operations. First, the curing chamber is vacuumed, and the pressure is controlled at 0.05MPa to 0.1MPa to ensure that the large bubbles inside the shell will move from high pressure to low pressure, so that the porosity between the composite layers is greatly reduced. Then turn on the ultrasonic device, and through the ultrasonic generator integrated on the inner wall of the core mold, control the frequency of the ultrasonic wave to 20kHz to 40kHz, the power to 300W to 600W, the amplitude to 20μm to 40μm, and the action time to 5 minutes to 8 minutes. In this way, two to three cycles of degassing are carried out to achieve effective removal of bubbles, especially bubbles between the contact gap between the head cap and the shell, and promote the uniform distribution of resin in the fiber gap. The effect diagram of the ultrasonic device degassing bubbles through the cavitation effect is as shown below Figure 3 (c) It mainly removes some small bubbles and breaks large bubbles into small bubbles that do not affect the performance of the shell.

[0058] Ultrasonic degassing using this method effectively reduced the shell porosity from 2% to 1%, thereby improving the reliability and durability of the shell.

[0059] Step 4) Heating and curing, removing the core mold:

[0060] a. After ultrasonic debubbling, place the shell in a curing chamber for curing. Specific curing parameters are: heating from room temperature to 90°C to 120°C at a rate of 25°C to 30°C / hour, maintaining the temperature for 2 to 4 hours. After curing, cool naturally to room temperature. During the curing process, maintain a uniform rotation of the composite shell at 2 revolutions per minute.

[0061] b. After curing, let it stand for 5 to 10 minutes, then remove the shell and dismantle the core mold device.

[0062] First, remove the two pairs of nuts on the mandrel that secure the connector plates at both ends, then remove the connector plates. This exposes the second set of nuts securing the positioning frame and removes them. After removing the positioning frame, remove the split mold, pull out the mandrel, and complete the removal of the core mold for the next assembly.

Claims

1. A method for manufacturing a rocket engine casing using an ultrasonically enhanced head cap winding and reinforcement engine casing manufacturing device, characterized in that: The ultrasonic enhanced head cap winding and reinforcement engine casing manufacturing device comprises a plurality of metal split molds (7), a core shaft (2), an ultrasonic vibration head device (3) and a positioning frame (8); a through hole is opened in the middle of the core shaft (2), and the through hole is used for the passage of the line of the ultrasonic vibration head device (3); the core shaft (2) is located inside the engine casing barrel section at the corresponding positions of the two ends thereof and is detachably connected with the positioning frame (8); the positioning frame (8) is used for positioning the split molds (7); the plurality of metal split molds (7) are combined to form a barrel, and each split mold (7) is provided with an ultrasonic vibration head device (3) inside. The ultrasonic vibration head device (3) includes an ultrasonic transducer (2-1), a horn (2-2), a vibration rod (2-3) and a rubber head (2-4); the vibration rod (2-3) is in the shape of an aluminum pen tip, the tip of the vibration rod (2-3) is a rubber head (2-4), and the ultrasonic vibration head device (3) is connected to the split mold by strong glue; the positioning skeleton (8) includes an annular portion that contacts the inner wall of the split mold, and the annular portion is connected by a skeleton and a core shaft screw that are evenly arranged in the circumference; the split mold (7) is provided with a dovetail-shaped protrusion, and the annular portion of the positioning skeleton (8) is provided with an engaging groove (4) that matches the protrusion; The method comprises the following steps: Step (1): assembling the device; Step (2): winding is performed on a core mold formed by a plurality of split molds (7): the barrel section is first wound in a spiral manner and then in a circumferential manner, and the head sections on both sides of the barrel section are wound in a stepped circumferential manner to form a stepped shape with decreasing height from the barrel section to the head section; Step (3): Adding a head cap (3-4): The head cap is preformed and made of the same material as the engine casing. The shape of the head cap is an ellipsoid with constant thickness. The head cap (3-4) is added to fill the height difference between the barrel section and the head section, and then the entire casing is spirally wound; Step (4): After the winding is completed, the shell is placed in a curing chamber for vacuum treatment. After a portion of the bubbles are discharged, the ultrasonic vibration head device (3) on the inner wall of the core mold is controlled to adjust the frequency, power, amplitude and action time of the ultrasonic wave to effectively remove the bubbles inside the shell; Step (5): Place the shell in a curing chamber and ensure the curing quality of the shell material by controlling the temperature, time and rotation speed.

2. The method according to claim 1, characterized in that The thickness of the spiral winding layer of the barrel section in step (2) is 2.5 mm, and the thickness of the circumferential winding layer is 2.2 mm; and the barrel section ply laying sequence is the optimal ply laying sequence of {[(15.1°), (-15.1°), (15.1°)], (90°)2}, 3 spiral winding layers and 2 circumferential winding layers; after the circumferential winding is completed, there will be a height difference of 2.2 mm between the head section and the barrel section; during the winding process, each layer is coated with glue to form a reinforcement layer.

3. The method according to claim 2, characterized in that The angle of the spiral winding in step (3) is [(15.1°), (-15.1°)], the number of the winding layer is 2, and the winding thickness is 1.7 mm; during the winding process, each layer is coated with glue to form a reinforcement layer.

4. The method according to claim 3, characterized in that In both steps (1) and (3), a dry winding process is adopted to unfold the T70012K unidirectional fiber bundle, release the prepreg tape from the reel and directly wind it on the core mold installed on the winding machine tooling, set the prepreg speed to 0.5m / min, the constant tension to 2.5N, and the temperature to 80-130℃.

5. The method according to claim 4, characterized in that Step (4) is specifically as follows: After winding, place it in the curing chamber, evacuate the curing chamber, and control the pressure at 0.05MPa to 0.1MPa; The ultrasonic vibration head device (3) is turned on, and the frequency of the ultrasonic wave is controlled to be 20kHz to 40kHz, the power to be 300W to 600W, the amplitude to be 20μm to 40μm, and the action time to be 5 minutes to 8 minutes; and two to three cycles are performed.

6. The method according to claim 5, characterized in that The specific parameters of the curing process in step (5) are as follows: heating from room temperature to 90°C to 120°C at a heating rate of 25°C to 30°C / h, maintaining the temperature for 2 to 4 hours, and naturally cooling to room temperature after the curing is completed; and maintaining the composite material shell uniformly rotating at a speed of 2 r / min during the curing process; After curing is completed, let it stand for 5 to 10 minutes, then remove the shell and dismantle the core mold device; Remove the two pairs of nuts on the core shaft that are used to fix the joint plates at both ends, and then remove the joint plates; remove the positioning frame, and after removing the positioning frame, remove the petal mold, pull out the core shaft, and complete the removal of the core mold.

7. A rocket engine casing, characterized in that: Manufactured using the method according to any one of claims 1 to 6, the shell is made of carbon fiber resin composite material.

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