CN-122014459-A - Threaded foam plug cover and forming method thereof

CN122014459ACN 122014459 ACN122014459 ACN 122014459ACN-122014459-A

Abstract

The application discloses a threaded foam blanking cover and a forming method thereof, which belong to the technical field of solid rocket engine nozzle blanking covers and are arranged at the tail part of a rocket engine nozzle; the sealing device comprises a blocking cover body, a blocking ring, a first trapezoidal thread structure, a second trapezoidal thread structure, a first sealing ring, a second sealing ring and a sealing ring, wherein the second trapezoidal thread structure is arranged on the inner side of the blocking ring, the first trapezoidal thread structure and the second trapezoidal thread structure are mutually matched and screwed and connected, the matching surfaces of the first trapezoidal thread structure and the second trapezoidal thread structure are constructed to generate mechanical self-locking and radial pressing force when screwed and fastened, so that the sealing connection of the blocking cover body and the blocking ring is realized, the sealing of a rocket engine spray pipe is realized, and the blocking cover body and the blocking ring are formed by foaming foamable polystyrene through one-time compression molding. The application effectively resists vibration loosening and ensures the structural stability under the conditions of durable connection and working condition.

Inventors

YANG XUBIN
QIN FENG
LIU LANGLANG
LI LONG
HE CHUANG

Assignees

陕西普利美材料科技有限公司

Dates

Publication Date: 20260512
Application Date: 20260415

Claims (10)

1. A threaded foam plug cap for installation on the aft portion of a rocket engine nozzle, comprising: the plug comprises a plug body (1), wherein a first trapezoid thread structure (2) is arranged on the outer side of the plug body (1); The retaining ring (3), the inner side of the retaining ring (3) is provided with a second trapezoid thread structure (4); The first trapezoidal thread structure (2) and the second trapezoidal thread structure (4) are mutually matched and screwed and connected, and the matching surfaces of the first trapezoidal thread structure (2) and the second trapezoidal thread structure (4) are configured to generate mechanical self-locking and radial pressing force when screwed and fastened so as to realize the sealing connection of the plug body (1) and the retainer ring (3), thereby realizing the sealing of a rocket engine spray pipe; the blanking cover body (1) and the retainer ring (3) are formed by foaming and one-time compression molding of foamable polystyrene.
2. A threaded foam plug according to claim 1, characterized in that the outside of the plug body (1) is coated with a silicone rubber sealing layer (5); the outer side and the inner side of the check ring (3) are coated with silicone rubber sealing layers (5); The thickness of the silicon rubber sealing layer (5) is 0.2-0.5mm.
3. A screw-type foam plug according to claim 1, characterized in that the plug body (1) has a first mating surface, the retainer ring (3) has a second mating surface, the first mating surface and the second mating surface being adapted; The first matching surface is provided with a first convergence angle, the second matching surface is provided with a second convergence angle, and the first matching surface and the second matching surface are oppositely arranged at the first convergence angle and the second convergence angle, so that radial interference is generated when the first matching surface and the second matching surface are pressed along the axial direction, and sealing and locking are realized.
4. A screw-type foam plug according to claim 3, characterized in that the maximum outer diameter of the plug body (1) is 135-139mm; The height of the blanking cover body (1) is 80-90mm; The thickness of the plugging cover body (1) is 30-50mm; the first convergence angle is 60-63 degrees; The maximum outer diameter of the retainer ring (3) is 100-110mm; The thickness of the retainer ring (3) is 20-26mm; The second convergence angle is 30-33 degrees.
5. A threaded foam plug according to claim 1, characterized in that the nominal diameter of the first (2) and second (4) trapezoidal thread structures is 50-65mm and the pitch is 3mm; The effective length of the first trapezoidal thread structure (2) and the second trapezoidal thread structure (4) is 25-30mm.
6. A screw-type foam plug according to claim 1, wherein the rocket engine nozzle tail comprises a nozzle front section, a throat liner (6) and a nozzle rear section which are coaxially arranged in sequence along the flow direction of the fuel gas; The laryngeal liner (6) has a converging section and an diverging section; The plug body (1) is positioned in the convergence section of the throat liner (6), and the outer peripheral surface of the plug body (1) is matched with the shape of the inner wall surface of the convergence section and is attached to the inner wall surface of the convergence section; The retainer ring (3) is located in the rear section of the nozzle and corresponds to the axial rear of the expansion section.
7. The forming method of the threaded foam plug cover is characterized by comprising the following steps of: S1, pre-foaming expandable polystyrene to obtain primary foaming beads; s2, performing secondary foaming on the primary foaming beads to obtain secondary foaming beads; s3, uniformly filling the secondary foaming beads into a mold of the blanking cover body and the retainer ring, ensuring that the secondary foaming beads are fully foamed and expanded, completely filling a mold cavity, and forming the blanking cover body (1) and the retainer ring (3) with trapezoid thread structures at one time, wherein the mold filled with the secondary foaming beads is completely immersed into boiling water for steam foaming, and the boiling water bath time is 45-60min; S4, taking the die out of boiling water, and performing cooling and demolding treatment to obtain a plugging cover body (1) and a check ring (3) with trapezoid thread structures; s5, assembling the blanking cover body (1) and the retainer ring (3) and installing the blanking cover body and the retainer ring at the tail of the rocket engine spray pipe.
8. The method for forming a threaded foam plug according to claim 7, wherein in S1, a quantitative expandable polystyrene is weighed for pre-foaming, the pre-foaming set temperature is 40-50 ℃, the pre-foaming time is 1-5 hours, wherein a ventilation system is kept to run continuously during the pre-foaming process, and complete decomposition of organic gas is ensured; In S2, the set temperature of the secondary foaming is 60-70 ℃, and the time of the secondary foaming is 10-30min, so that the secondary foaming beads are uniform in volume, smooth in surface and free from adhesion.
9. The method for forming a screw-type foam plug according to claim 7, wherein in S4, the cooling temperature of the cooling and demolding treatment is 20-25 ℃, and the mold is opened after cooling to room temperature; And curing the plugging cover body (1) and the check ring (3) with the trapezoid thread structures, wherein the curing temperature is 45-55 ℃ and the curing time is 6-7h.
10. The method for forming a threaded foam plug according to claim 7, wherein S5 comprises: Coating a silicone rubber sealing layer (5) on the outer side of the plug body (1) and the inner side and the outer side of the retainer ring (3) to ensure that threads are completely covered and no missing coating phenomenon exists, wherein the thickness of the silicone rubber sealing layer (5) is 0.2-0.5mm; The plug body (1) is axially fed from the front section of the spray pipe, pushed into the convergence section of the throat liner (6), and the outer surface of the plug body (1) is attached to the inner wall surface of the convergence section; Feeding the retainer ring (3) axially from the rear section of the nozzle, so that the retainer ring (3) is positioned axially behind the expansion section of the throat liner (6); the retaining ring (3) is connected with the trapezoid thread structure of the plugging cover body (1) to finish the installation and fixation of the plugging cover; Solidifying for 18-24h at room temperature, and the relative humidity of the environment is less than or equal to 60%.

Description

Threaded foam plug cover and forming method thereof Technical Field The application relates to a threaded foam plug cover and a forming method thereof, and belongs to the technical field of solid rocket engine nozzle plug covers. Background The solid rocket engine nozzle plug is a key sealing component of an engine system, and mainly has the effects of keeping the inside of a nozzle sealed during storage and transportation of an engine, preventing moisture and impurities from entering, and being reliably opened according to preset pressure when the engine is ignited, so that smooth discharge of fuel gas is ensured. The traditional blanking cover is mainly divided into a metal blanking cover and a rubber blanking cover. The metal blanking cover has higher mechanical strength and stable opening pressure, but can generate high-speed fragments after the engine is ignited, and the fragments can impact the nozzle convergent section and the throat liner, so that the normal operation reliability of the engine is affected. Although the rubber blanking cover can avoid damage of fragments, the rubber blanking cover has the problem of insufficient temperature resistance, is easy to generate ablation failure under high-temperature gas flushing, and is easy to generate aging phenomenon after long-term storage, thereby influencing the sealing performance. The existing foam blanking cover technology effectively solves the limitation of the traditional materials. The foam blanking cover made of polystyrene beads and other materials realizes the balance of light weight and controllable crushing through special structural design and forming process. However, the existing foam plugging cover is mostly bonded to the expansion section of the spray pipe by using epoxy resin as an adhesive, and the bonding interface is a weak link. Because of the foam surface characteristics, the interfacial bond strength and long-term stability face a challenge, and are prone to becoming a source of failure under thermal cycling or vibration conditions. Disclosure of Invention According to one aspect of the application, a threaded foam plug is provided that is effective against vibration loosening, ensuring structural stability under permanent connection and operating conditions. A threaded foam plug for mounting on the aft portion of a rocket engine nozzle, comprising: The plug comprises a plug body, wherein a first trapezoid thread structure is arranged on the outer side of the plug body; the inner side of the check ring is provided with a second trapezoid thread structure; The first trapezoidal thread structure and the second trapezoidal thread structure are mutually matched and screwed and connected, and the matching surfaces of the first trapezoidal thread structure and the second trapezoidal thread structure are constructed to generate mechanical self-locking and radial pressing force when screwed and fastened so as to realize the sealing connection of the blanking cover body and the retainer ring, thereby realizing the sealing of the rocket engine spray pipe; The plugging cover body and the check ring are formed by foaming disposable compression molding of foamable polystyrene. Further, the outer sides of the plug body are coated with silicone rubber sealing layers; the outer side and the inner side of the check ring are coated with silicone rubber sealing layers; The thickness of the silicone rubber sealing layer is 0.2-0.5mm. Further, the plugging cover body is provided with a first matching surface, the retainer ring is provided with a second matching surface, and the first matching surface is matched with the second matching surface; The first matching surface is provided with a first convergence angle, the second matching surface is provided with a second convergence angle, and the first matching surface and the second matching surface are oppositely arranged at the first convergence angle and the second convergence angle, so that radial interference is generated when the first matching surface and the second matching surface are pressed along the axial direction, and sealing and locking are realized. Further, the maximum outer diameter of the plugging cover body is 135-139mm; The height of the plugging cover body is 80-90mm; the thickness of the plugging cover body is 30-50mm; the first convergence angle is 60-63 degrees; the maximum outer diameter of the retainer ring is 100-110mm; The thickness of the retainer ring is 20-26mm; The second convergence angle is 30-33 degrees. Further, the nominal diameter of the first trapezoidal thread structure and the second trapezoidal thread structure is 50-65mm, and the thread pitch is 3mm; The effective length of the first trapezoidal thread structure and the second trapezoidal thread structure is 25-30mm. Further, the tail part of the rocket engine spray pipe comprises a spray pipe front section, a throat liner and a spray pipe rear section which are coaxially arranged in sequence along the fl