Device and method for manufacturing engine shell reinforced by winding of ultrasonic enhanced end socket cap

Abstract

The invention belongs to the field of engine shell preparation, and particularly relates to a manufacturing device and method for an engine shell reinforced by winding an ultrasonic enhanced end socket cap. Comprising a plurality of metal split dies, a mandrel, an ultrasonic vibration head device and a positioning framework, a through hole is formed in the middle of the mandrel, a circuit of the ultrasonic vibration head device passes through the through hole, positioning frameworks are detachably connected to the corresponding positions, located at the two ends of the cylinder body section of the engine shell, in the mandrel and used for positioning the split dies, and the multiple metal split dies are combined to form a cylinder. And an ultrasonic vibration head device is arranged in each split mold. According to the method, the air tightness, the uniformity and the structural strength of the shell barrel body section and the end socket section are improved through winding reinforcement of the end socket cap, and the porosity is reduced by combining the metal detachable core mold with the ultrasonic reinforcing device, so that the performance and the reliability of the rocket engine are improved.

Description

Technical Field

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

[0002] The preparation of rocket engine shells made of carbon fiber composite materials usually adopts an integral molding winding process, which is formed by winding the pre-impregnated carbon fiber on the core mold. However, the composite shell produced by this process can achieve equal stress in the barrel section, but at the head, due to the large change in structural stiffness and uneven thickness distribution, stress concentration will occur. At the same time, carbon fiber reinforced composite materials are brittle materials and are more sensitive to structural discontinuities. Therefore, it is often difficult to ensure the sealing and structural integrity of the head section, which limits the performance and reliability of the rocket engine.

[0003] Compared with the traditional winding process in the molding of the engine casing, the head cap winding reinforcement can effectively simplify the winding process, improve the sealing and structural integrity of the head section, reduce stress concentration, and thus improve the performance and reliability of the rocket engine. However, there are problems such as residual bubbles 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 object 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 and reinforcement engine casing manufacturing device, including a plurality of metal split molds, a mandrel, 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 detachably connected to the corresponding positions at both ends of the engine casing barrel section. The positioning skeleton is used to position the split mold. Multiple metal split molds are combined to form a barrel body, and an ultrasonic vibration head device is provided inside each split mold.

[0007] Further, 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 in contact with 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 engaging groove that matches the protrusion.

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

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

[0012] Step (2): winding on a core mold formed by a plurality of split molds: the barrel section is firstly spirally wound and then circumferentially wound, and the head sections on both sides of the barrel section are circumferentially wound in a stepwise manner to form a step-like shape with a 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 from the barrel section to the head section, and then the entire casing is spirally wound;

[0014] Step (4): After 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 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, 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 number of the winding layers is 2, and the winding thickness is 1.7 mm; during the winding process, each winding layer is coated with glue to form a reinforcement layer.

[0018] Furthermore, in both step (1) and step (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, the prepreg speed is set to 0.5m / min, the constant tension is set to 2.5N, 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 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; perform two to three cycles.

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

[0023] After the 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 by 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, avoiding the problems of stress concentration at the critical point of circumferential winding and spiral winding. In addition, the spiral-circumferential fiber winding process is adopted at the step, the number of linear alternations is less, the stress on the composite layer is reduced, and the overall spiral winding is adopted after adding the head cap 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 is helpful to achieve the lightweight of the rocket engine shell.

[0028] (2) High air tightness: The present invention uses vacuum treatment and ultrasonic degassing technology to effectively reduce the porosity of the connection between the head cap and the barrel section and also has a good removal effect on interlayer bubbles. The porosity of the composite shell is less than 1%, which improves 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 is easy to disassemble and assemble, has high positioning accuracy, long service life and low production cost; and the ultrasonic vibration tool head is designed to be in the shape of a pen tip and rubberized to minimize the mechanical damage to the shell and the core mold itself during ultrasonic high-frequency vibration. Reasonable layer design also reduces winding costs. 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 an ultrasonic local schematic diagram.

[0031] Figure 2 It 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-annular 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 in conjunction with 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 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 embedded with the positioning skeleton 8 through the embedded 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, and each frame has a reserved fitting groove near the top for connecting with the split mold. The split mold is assembled and disassembled by sliding through the designed protruding part and the fitting groove. The positioning frame is assembled and disassembled by bolts, nuts and mandrels.

[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 consists of six groups, among which 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 Figure 1 The grooves marked with 4 in (a) are fitted together to ensure structural stability.

[0041] At the same time, the mandrel 2 of the core mold is a key component that connects 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 mandrel 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 the transducer to convert the electrical signal into a mechanical vibration signal and then transmit it to the vibrating tool head to form ultrasonic vibration. After adjusting the amplitude by amplitude change, the vibration split mold 7 of the rubber head 2-4 transmits it to the composite material shell.

[0042] According to the principle of ultrasonic vibration, the vibration generated by the ultrasonic vibration device will be transmitted through the board material. This vibration can be transmitted through the entire structure of the board, not just limited to the area directly in contact with the ultrasonic vibration device. Therefore, as shown in the figure, the ultrasonic device is precisely positioned in the middle area of ​​the split mold to ensure that the vibration energy can be effectively and symmetrically transmitted to the winding area of ​​the composite material. The microjets and shock waves generated by the cavitation effect of ultrasonic vibration can crush or remove the bubbles in the gaps without affecting the performance of the product, especially promoting the removal of bubbles in the gaps in the winding of the head cap and the barrel section.

[0043] During the installation and disassembly of the core mold, the modular design can ensure that the ultrasonic device and the 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 a dry winding process, uses a special fiber yarn spreading device to unfold the T70012K unidirectional fiber bundle, releases the prepreg tape from the reel and directly winds it on the core mold installed on the winding machine tooling, and the prepreg speed is set to 0.5m / min. Figure 3 As shown in (a), in the tension control and heating device, the constant tension is set to 2.5N and the temperature is set to 80-130℃. 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 on the core mold. The function of the nozzle is to control the direction of the carbon fiber tape to ensure the accuracy and consistency of the winding process.

[0046] Spiral winding is a composite manufacturing technique in which the 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 the 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 is the process of winding the fiber along the axis of the core mold to form a ring-shaped fiber path. During the hoop winding process, the winding head moves in a hoop path on the core mold, releasing the prepreg and winding it evenly on 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, this winding method makes the strength of the barrel section after winding equal to or greater than the traditional winding method, and on the other hand, it increases the contact thickness by T C After the head cap is installed, it can be fitted to reduce the gap between the head and the barrel during the production process. Then the whole is spirally wound again to reinforce the contact section and the shell itself and enhance the mechanical properties of the shell. Figure 3 shown.

[0049] The explosion position of rocket engine shell safety failure is in the barrel section. The main purpose is to provide circumferential radial stress through circumferential winding, while the spiral winding provides axial force to protect the head. Therefore, the inner spiral plus circumferential winding and the outer spiral winding can be used for laying. At the same time, the overall spiral winding on the outside can make the overall structure of the head cap and the shell more stable.

[0050] The winding process of the rocket engine casing includes accurately calculated annular winding and spiral winding, and the winding angle calculation: according to the isopolar hole structure according to 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 that the thickness of the spiral winding layer of the barrel section is 2.5mm, and the thickness of the hoop winding layer is 2.2mm. Using MATLAB software combined with the cubic spline function method and geometric method, the optimal laying order of 2 spiral winding layers and 2 hoop winding layers was determined.

[0052] The laying sequence of the barrel section is determined to be {[(15.1°), (-15.1°), (15.1°)], (90°)2} according to finite element simulation. After adding a head with a thickness of 2.2mm, the overall spiral winding reinforcement strategy is carried out. The spiral winding angle is 40°, the winding layer is 2 layers, and the winding thickness is 1.7mm.

[0053] The shell bursting pressure under this winding method is increased from 18MPa to 21Mpa, which is about 16% and has a significant effect.

[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 on 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 evacuated 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 debubbling work are carried out to achieve effective removal of bubbles, especially bubbles in the contact gap between the head cap and the shell, and promote the uniform distribution of resin in the fiber gaps. The effect diagram of the debubbling effect of the ultrasonic device 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 the ultrasonic debubbling work is completed, the shell is placed in the curing chamber for curing. The specific parameters of the curing process are: from room temperature to 90℃ to 120℃ at a heating rate of 25℃ to 30℃ / h, keep warm for 2 hours to 4 hours, and naturally cool to room temperature after curing. And keep the composite shell rotating evenly at a speed of 2 turns / min during the curing process.

[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 are used to fix the joint plates at both ends, and then remove the joint plates. After exposing the first set of nuts used to fix the positioning frame, remove them. After removing the positioning frame, remove the petal mold, pull out the mandrel, and complete the removal of the core mold for the next assembly.

Claims

1. Ultrasonic enhanced head cap winding and reinforcement engine casing manufacturing device, characterized in that: It 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 formed in the middle of the core shaft (2), through which a line of an ultrasonic vibration head device (3) passes. A positioning frame (8) is detachably connected to the core shaft (2) at corresponding positions at both ends of the engine casing barrel section. The positioning frame (8) is used to position the split-flap mold (7). A plurality of metal split-flap molds (7) are combined to form a barrel, and an ultrasonic vibration head device (3) is arranged inside each split-flap mold (7).

2. The device according to claim 1, characterized in that The ultrasonic vibration head device (3) comprises an ultrasonic transducer (2-1), a horn (2-2), a vibration rod (2-3) and a rubber head (2-4); The vibrating rod (2-3) is in the shape of an aluminum pen tip, the tip of the vibrating rod (2-3) is a rubber head (2-4), and the ultrasonic vibration head device (3) is connected to the petal mold by strong glue.

3. The device according to claim 2, characterized in that The core mold frame (8) includes an annular portion in contact with the inner wall of the split mold, and the annular portion is connected through a frame and a core shaft screw that are evenly arranged in the circumferential direction; a dovetail-shaped protrusion is provided on the split mold (7), and the annular portion of the core mold frame (8) is provided with an engaging groove (4) that matches the protrusion.

4. A method for manufacturing a rocket engine casing using the device according to any one of claims 1 to 3, characterized in that: The steps include: 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 firstly spirally wound and then circumferentially wound, and the head sections on both sides of the barrel section are circumferentially wound in a stepwise manner to form a step-like shape with a 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 equal thickness. The head cap (3-4) is added to fill the height difference from the barrel section to the head section, and then the entire casing is spirally wound; Step (4): After winding is completed, the shell is placed in a curing chamber for vacuum treatment. After part 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.

5. The method according to claim 4, 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, 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.

6. The method according to claim 4, characterized in that The angle of the spiral winding in step (3) is [(15.1°), (-15.1°)], the number of the winding layers is 2, and the winding thickness is 1.7 mm; during the winding process, each winding layer is coated with glue to form a reinforcement layer.

7. The method according to claim 4, characterized in that In both step (1) and step (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, set the constant tension to 2.5N, and set the temperature to 80-130°C.

8. 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 20 kHz to 40 kHz, the power to be 300 W to 600 W, the amplitude to be 20 μm to 40 μm, and the action time to be 5 minutes to 8 minutes; this is carried out for two to three cycles.

9. The method according to claim 8, 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, keeping the temperature for 2 to 4 hours, and naturally cooling to room temperature after the curing is completed; and during the curing process, the composite material shell is kept rotating uniformly at a speed of 2r / min; After the 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.

10. A rocket engine casing, characterized in that: The shell is manufactured by the method according to any one of claims 1 to 9, and the shell material is a carbon fiber resin composite material.

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