Pre-buried wire covering sleeve and forming method

Abstract

The present invention relates to the technical field of sheaths for pre-buried conductor structures for solid rocket engine propellants, and specifically discloses a pre-buried conductor sheath and a molding method. The sheath is provided with a wire pre-buried cavity that provides a controllable deformation space for the conductor in the cross-sectional direction and the length direction, and ensures that the distance from the conductor to the outer wall of the sheath is always within a safe distance range; the conductor is located in the wire pre-buried cavity. The present application provides a wire pre-buried cavity; realizes that the pre-buried conductor has the possibility of deformation in the cross-sectional direction and the length direction; the distance from the conductor to the outer wall of the sheath is always within a safe distance range in the working state; avoids damage to the conductor due to external force during the molding process; and provides support for the three-step integral molding of the entire pre-buried conductor sheath through a molding method, thereby avoiding the uneven thickness of the pre-buried conductor sheath prepared in the prior art and the problem of the conductor being crushed during the molding process.

Description

Technical Field

[0001] The invention relates to the technical field of covering sleeves for pre-buried wire structures for solid rocket engine propellants, in particular to a pre-buried wire covering sleeve and a molding method thereof. Background Art

[0002] The propellant sheath is one of the important components of the solid rocket engine charge combustion chamber. The function of the sheath is to limit combustion, buffer and prevent heat, so as to protect the propellant for safe use. The most common propellant sheath is made of rubber insulation material through molding or injection molding. It has a closed end and an open end structure. Most of them are used for free-loading propellants. The safe ignition method for igniting the propellant is generally tail ignition. However, the propellant of the second pulse engine of some dual-pulse engines or the secondary propellant of the single-chamber dual-thrust engine are all sheath structures, which are end-face combustion. The ignition cartridge is installed at the tail of the propellant, but the igniter is located at the head. Especially in solid rocket engines with dual-pulse or multi-pulse structures, how to protect the safety and reliability of the wires used for ignition connections during operation has always been a difficult problem in this field. For example, Figure 5 The commonly used method shown is to pre-embed the wire 4 in the insulation layer of the covering sleeve 6, leaving only the connectors at both ends. The method adopted is to wrap the covering sleeve 6 around the outside of the wire 4 and then mold the whole, or pre-form the entire covering sleeve 6 first, and then pre-embed the wire 4 and then co-vulcanize the whole. This type of method has the defects of poor consistency and uneven thickness of the wire heat protection layer, and may even cause the wire to break due to external force, affecting normal use. Summary of the Invention

[0003] According to one aspect of the present application, a pre-buried wire covering sleeve is provided to solve the problem that the existing covering sleeve is integrally formed, resulting in uneven thickness of the covering sleeve or internal wire breakage. The specific solution is as follows:

[0004] A pre-buried wire covering sleeve, the wire covering sleeve comprising a covering sleeve and a wire;

[0005] The sheath is provided with a wire pre-buried cavity which provides a controllable deformation space for the wire in the cross-sectional direction and the length direction, and ensures that the distance between the wire and the outer wall of the sheath is always within a safe distance range;

[0006] The safety distance range means that the maximum distance between the conductor and the outer wall of the sheath meets the installation requirements of the conductor sheath, and the minimum distance between the conductor and the outer wall of the sheath is greater than the pressure-resistant thickness during molding and the temperature-resistant thickness under high-temperature working conditions;

[0007] The wire is located in the wire pre-embedded cavity.

[0008] Preferably, the wire pre-buried cavity is a hollow cavity formed by a wire pre-buried groove provided on the inner wall of the outer sheath and an inner protective layer covering the wire pre-buried groove;

[0009] The wire embedded groove is arranged along the extension direction of the outer covering sleeve and is integrally formed with the outer covering sleeve. The wire embedded groove provides a placement path and deformation space for the wire;

[0010] After the wire is laid in the wire embedded groove, the inner protective layer is formed integrally with the outer sheath and the wire;

[0011] The deformation space is configured to provide a space to protect the conductor within a controllable range when the conductor is subjected to external forces in the cross-sectional direction and the length direction based on the conductor pre-buried groove;

[0012] The lateral boundary of the controllable range space is determined according to the deformation of the conductor diameter in the cross-sectional direction, and the longitudinal boundary of the controllable range space is determined according to the total length of the conductor and the dynamic displacement of the conductor during operation.

[0013] Preferably, the distance between the wire embedded groove and the outer wall of the outer covering sleeve is determined according to the size of the deformation space and the overall thickness of the outer covering sleeve, the groove width of the wire embedded groove is determined according to the diameter of the wire, and the length of the wire embedded groove is determined according to the length of the wire and design requirements.

[0014] Preferably, the conductor embedded slot is in a serpentine shape formed by continuous periodic or non-periodic bending units;

[0015] The difference in lateral width of the periodic or non-periodic bending units is less than 0.2 mm.

[0016] Preferably, the external force factors acting on the wire in the cross-sectional direction and the length direction include: the wire being squeezed by the external force in the cross-sectional direction, the expansion, contraction or bending in the cross-sectional direction due to temperature changes, and the change in the length of the wire caused by the stretching, compression or vibration of the wire in the length direction.

[0017] According to another aspect of the present application, a method for forming a pre-buried wire sheath is provided, the method comprising:

[0018] S1, using insulating rubber to prepare an outer sheath having an S-shaped wire pre-buried groove, wherein the wire pre-buried groove is provided on an inner wall of one side of the outer sheath along an extension direction of the outer sheath;

[0019] S2, treating the surface of the conductor embedded groove to obtain a good bonding interface;

[0020] S3, fixing the wire in the wire embedded groove, with both ends of the wire located outside the ends of the outer sheath;

[0021] S4, covering and fixing the inner protective layer on the side of the conductor facing away from the conductor embedded groove;

[0022] S5, preparing a pre-buried wire covering sleeve by vulcanizing the inner protective layer, the wire and the outer covering sleeve.

[0023] Preferably, the rubber used to prepare the outer covering is made of the same material as that of the inner protective layer.

[0024] Preferably, the vulcanization process is as follows: first, heating from room temperature to 120°C for 2 hours and keeping the temperature for 1 hour;

[0025] Afterwards, the temperature was raised from 120°C to 160°C in 1 h and kept at this temperature for 2 h;

[0026] Finally, after the heat preservation is completed, the temperature is lowered to 60℃ and the pressure is maintained at 80MPa / cm 2 ~100MPa / cm 2 .

[0027] Preferably, in S1, the process of preparing the outer covering is:

[0028] 1) Preheat the outer covering mold. The preheating temperature of the outer covering mold is 100°C and kept warm for at least 1 hour;

[0029] 2) Place the weighed insulation rubber into the preheated outer covering mold and press it;

[0030] 3) Curing after mold closing;

[0031] 4) After demoulding, an outer covering sleeve with a serpentine-shaped wire embedded groove on the inside is obtained.

[0032] Preferably, the curing process is:

[0033] First, after closing the mold, keep it warm for 20 minutes without applying pressure;

[0034] Then, pressurize to 100 MPa / cm 2 At the same time, the temperature is raised from the preheating temperature to 150°C over 1 hour and kept warm for 2 hours; finally, the heating is stopped, the pressure is maintained and the temperature is lowered to 60°C to complete the curing.

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] The present application provides a wire pre-buried cavity in the covering sleeve, which provides a space for the wire to be deformed in a controllable manner in the cross-sectional direction and the length direction, and ensures that the distance between the wire and the outer wall of the covering sleeve is always within a safe distance range; the wire pre-buried in the covering sleeve has the possibility of being deformed in the cross-sectional direction and the length direction; at the same time, the distance between the wire and the outer wall of the covering sleeve is always within a safe distance range, so as to avoid the wire being damaged by external force due to the distance from the wire to the outer wall of the covering sleeve being too small during the molding process; the wire being easily burned through due to the distance from the wire to the outer wall of the covering sleeve being too small during the working state; and the wire being too large to the outer wall of the covering sleeve, so that the entire pre-buried wire covering sleeve does not meet the installation requirements.

[0037] The present application manufactures the sheath in three steps, wherein the wire pre-embedded cavity is formed by a wire pre-embedded groove provided on the inner wall of the outer sheath and an inner protective layer covering the wire pre-embedded groove, forming a hollow cavity for placing the wire. The wire pre-embedded groove provides a placement path and deformation space for the wire. The wire pre-embedded groove and the outer sheath are integrally formed, first providing a safe installation space for the wire. Then, after the wire is laid in the wire pre-embedded groove, the inner protective layer is integrally formed with the outer sheath and the wire. This avoids the problem of the wire and the sheath being directly molded together in the prior art, which causes the wire to be broken during the molding process due to excessive pressure, or uneven pressure resulting in uneven thickness of the sheath after pressing, causing the distance between the wire and the outer wall of the sheath to vary, resulting in some wires being too far away from the outer wall in radial direction, resulting in insufficient installation accuracy, while some wires are too far away from the outer wall, making them prone to burn-through.

[0038] By setting the wire embedded groove to a serpentine shape, a margin is left for the deformation of the wire in the extension direction and radial direction, and at the same time, the radial deformation and extension direction deformation of the wire in the later use process are within a controllable range.

[0039] The method for forming a pre-embedded wire covering sleeve provided in the present application comprises the following steps: first, prefabricating an outer covering sleeve with a wire pre-embedded groove; then, fixing the wire in the wire pre-embedded groove; and covering the portion of the wire outside the wire pre-embedded groove with an inner protective layer, so that the inner protective layer and the outer covering sleeve form an insulating protective cavity for the wire, and wrapping the wire in the cavity; finally, the inner protective layer, the wire, and the outer covering sleeve are vulcanized together through a vulcanization process to prepare the pre-embedded wire covering sleeve, so that the distance between the wire and the outer wall of the covering sleeve and the free length extending from the end of the covering sleeve meet the design requirements; and providing support for dividing the covering sleeve into three steps for production.

[0040] The thermal insulation rubber of the inner protective layer and the outer covering sleeve is the same rubber (the thermal insulation rubber is made of the same material), so that the thermal insulation performance of the entire covering sleeve is consistent and its stability is maintained. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1A side view of a pre-buried wire covering sleeve in one embodiment of the present application;

[0042] Figure 2 This is a schematic diagram of the installation of a wire embedded groove and a wire in a pre-embedded wire sheath in one embodiment of the present application;

[0043] Figure 3 This is a schematic structural diagram of an outer sheath in a pre-buried wire sheath in one embodiment of the present application;

[0044] Figure 4 This is a schematic diagram of the installation of an outer covering sleeve, a conductor, an inner protective layer, and an airbag in a method for forming a pre-buried conductor covering sleeve in one embodiment of the present application;

[0045] Figure 5 It is a structural diagram of an existing covering sleeve;

[0046] In the figure: 1. Outer covering sleeve; 2. Inner protective layer; 3. Wire embedded groove; 4. Wire; 5. Airbag; 6. Covering sleeve. DETAILED DESCRIPTION

[0047] like Figure 1-3 A pre-buried wire covering sleeve is provided, and the wire covering sleeve comprises a covering sleeve and a wire;

[0048] The sheath is provided with a wire pre-buried cavity which provides a controllable deformation space for the wire in the cross-sectional direction and the length direction, and ensures that the distance between the wire and the outer wall of the sheath is always within a safe distance range;

[0049] The safety distance range means that the maximum distance between the conductor and the outer wall of the sheath meets the installation requirements of the conductor sheath, and the minimum distance between the conductor and the outer wall of the sheath is greater than the pressure-resistant thickness during molding and the temperature-resistant thickness under high-temperature working conditions;

[0050] The wire is located in the wire pre-embedded cavity.

[0051] It should be noted that:

[0052] The coating in this application is a propellant coating of a solid rocket engine charge combustion chamber. Therefore, the coating described in this application is a coating with flame retardant and heat insulation functions, which is used to protect the wires from being burned through.

[0053] For pulse rocket engines, in order to adapt to the vibration and deformation of the pulse rocket during operation, the wire in the sheath needs to be deformable in the cross-sectional direction (radial) and the length direction (axial), and the deformation of the wire in the cross-sectional direction and the length direction cannot be too large. Based on this, the present application provides a wire pre-embedded cavity in the sheath to ensure that the wire has deformation space in the cross-sectional direction and the length direction of the wire, while at the same time ensuring that the deformation of the wire in the cross-sectional direction and the length direction of the wire is within the design range;

[0054] Due to the limited internal space of the pulse rocket, the pre-embedded covering sleeve needs to be reasonably arranged in a small space. Therefore, the overall thickness of the pre-embedded covering sleeve should be uniform to meet the installation accuracy. This means that when the size of the wire is determined, the size of the wire away from the outer wall of the covering sleeve should be uniform and the difference should not be too large. When the size difference between the wire and the outer wall of the covering sleeve is large, when the size of the wire away from the outer wall of the covering sleeve is too large, the radial size of the entire pre-embedded covering sleeve is too large, resulting in insufficient radial installation space; when the size of the wire away from the outer wall of the covering sleeve is too small, it is easy to be crushed during the molding process, and in the later use process, the protective thickness of the wire covering sleeve is too small, and the wire is easy to be burned through / burned. Based on this, the present application sets a wire pre-embedded cavity to easily limit the size of the wire away from the outer wall of the covering sleeve. While ensuring that the pre-embedded covering sleeve meets the installation accuracy, the distance from the wire to the outer wall of the covering sleeve is always within a safe distance range during the molding process and in the later working state.

[0055] Furthermore, the wire pre-buried cavity is a hollow cavity formed by a wire pre-buried groove provided on the inner wall of the outer sheath and an inner protective layer covering the wire pre-buried groove;

[0056] The wire embedded groove is arranged along the extension direction of the outer covering sleeve and is integrally formed with the outer covering sleeve. The wire embedded groove provides a placement path and deformation space for the wire;

[0057] After the wire is laid in the wire embedded groove, the inner protective layer is formed integrally with the outer sheath and the wire;

[0058] The deformation space is configured to provide a space to protect the conductor within a controllable range when the conductor is subjected to external forces in the cross-sectional direction and the length direction based on the conductor pre-buried groove;

[0059] The lateral boundary of the controllable range space is determined according to the deformation of the conductor diameter in the cross-sectional direction, and the longitudinal boundary of the controllable range space is determined according to the total length of the conductor and the dynamic displacement of the conductor during operation.

[0060] It should be noted that:

[0061] In conventional technology, the covering sleeve is an integrated structure. During molding, the covering sleeve is molded together with the conductor, or the entire covering sleeve is pre-molded first, and then the conductor is pre-embedded and the whole is co-vulcanized. During molding, the conductor is molded together with the covering sleeve, which is easy to cause the internal break of the conductor due to external force. Pre-molding the covering sleeve first, and then pre-embedding the conductor and co-vulcanizing the whole leads to uneven thickness of the covering sleeve. Based on this, in the present application, the pre-embedded conductor covering sleeve includes: an outer covering sleeve, a conductor pre-embedded groove located on the side of the outer covering sleeve facing the inner protective layer, an inner protective layer located on the inner side of the outer covering, and a conductor located in a conductor pre-embedded groove and an inner protective layer. The conductor pre-embedded groove is formed by the conductor pre-embedded groove on the inner wall of the outer covering sleeve and the inner protective layer covering the conductor pre-embedded groove to form a hollow cavity for placing the conductor. The pre-embedded conductor groove is arranged on the inner wall of the outer covering sleeve along the length direction of the outer covering sleeve, and the pre-embedded conductor groove is integrally molded with the outer covering sleeve. The entire pre-embedded conductor covering sleeve is manufactured in three steps, specifically:

[0062] First, a pre-buried wire trough for laying / arranging the wires is prepared, providing a safe installation space for the wires and an outer sheath of uniform thickness, ensuring a uniform distance between the wires and the outer wall of the sheath. After the wires are laid in the pre-buried wire trough, the inner protective layer, wires, and outer sheath are molded together. This prevents the sheath from being molded together with the wires and broken by external forces, while also ensuring that the distance between the wires and the outer wall of the sheath remains within a safe range.

[0063] Furthermore, the distance between the wire embedded groove and the outer wall of the outer covering sleeve is determined according to the size of the deformation space and the overall thickness of the outer covering sleeve, the groove width of the wire embedded groove is determined according to the diameter of the wire, and the length of the wire embedded groove is determined according to the length of the wire and design requirements.

[0064] It should be noted that:

[0065] In the present application, the distance between the wire pre-buried groove and the outer wall of the outer covering sleeve shall comprehensively consider the size of the deformation space and the overall thickness of the outer covering sleeve. The groove width of the wire pre-buried groove is determined according to the diameter of the wire. In order to allow the wire to be smoothly placed in the pre-buried groove, while ensuring that the wire has a suitable space in the groove, it will not be difficult to install or squeeze the wire because the groove is too narrow, and the wire will not shake unstably in the groove because the groove is too wide, so the groove width must be adapted to the diameter of the wire. The length of the wire pre-buried groove: The determination of its length shall take into account the actual length of the wire and the design requirements. The length of the wire pre-buried groove determines that the pre-buried groove must at least be able to accommodate the wire, and the design requirements may include factors such as the arrangement of the wire, the reserved margin, and the connection requirements with other components, which will affect the final length setting of the wire pre-buried groove.

[0066] The deformation space is reserved to accommodate deformation of the conductor caused by various external forces during use. This includes dimensional changes in the cross section caused by external forces, expansion, contraction, or bending due to temperature changes, and longitudinal dimensional changes caused by stretching, compression, or vibration. The space is kept within a controllable range. The overall thickness of the outer sheath affects the structural strength and safety of the connection between the conductor pre-buried slot and the outer wall of the outer sheath.

[0067] For example, in one embodiment of the present application, in order to ensure that the pre-buried wire covering can be smoothly installed in the rocket engine while ensuring that the wire pre-buried in the covering is not burned through, the thickness of the outer covering is set to 2mm~3mm, and the diameter of the wire is 1.5mm~2mm. Based on the deformation of the wire in the cross section being within ±0.2mm and the deformation of the wire in the length direction being within ±0.5mm, the distance between the wire pre-buried groove and the outer wall of the outer covering is set to 1.5mm~3mm. On the one hand, the radial accuracy of the wire is guaranteed, and on the other hand, the wire is placed within the flame-retardant and heat-insulating range formed by the covering to prevent it from being burned through; the groove width of the wire pre-buried groove is set to 5mm to provide for the deformation of the wire in the radial direction.

[0068] Furthermore, the conductor embedded slot is in a serpentine shape formed by continuous periodic or non-periodic bending units;

[0069] The difference in lateral width of the periodic or non-periodic bending units is less than 0.2 mm.

[0070] It should be noted that:

[0071] In order to realize the possibility of deformation of the conductor in the cross-sectional direction and the length direction during operation, the present application provides space for deformation of the conductor in the cross-sectional direction and the length direction by setting the conductor embedded groove into a serpentine shape;

[0072] At the same time, in order to ensure that the deformation of the wire in the cross-sectional direction in the wire embedded groove is consistent, in one embodiment of the present application, the wire embedded groove is a serpentine shape formed by continuous periodic bending units arranged along the extension direction of the outer sheath.

[0073] In the present application, the serpentine shape includes but is not limited to any one of a serpentine shape, a wave shape, and a zigzag shape, and is preferably a serpentine structure.

[0074] Among them, the bending unit in the serpentine structure is a slightly curved S-shaped structure, that is, the curvature of the S curve is small, thus forming a serpentine structure, such as Figure 2As shown, the minimum width of the wire pre-buried groove is slightly larger than the wire diameter, and the transverse width difference of the periodic bending unit is set to be less than 0.2mm (that is, the left and right amplitude difference does not exceed 0.2mm) as the maximum width of the wire pre-buried groove, so as to ensure that the distance between the wire and the outer wall of the outer sheath is uniform. Since the outer sheath is located on the outside of the wire, the distance between the wire and the outer wall of the outer sheath is the same as the distance between the wire and the outer wall of the entire sheath. Therefore, by ensuring the uniform distance between the wire and the outer wall of the outer sheath, the distance between the wire and the outer wall of the entire sheath is prevented from being burned through due to the distance between the wire and the outer wall of the entire sheath being lower than the safe value, and the distance between the wire and the outer wall of the entire sheath is prevented from being too large, which affects installation. The deformation of the wire in the cross-sectional direction is ensured to be within a controllable range, so that the distance between the wire and the outer wall of the entire sheath is within a safe range.

[0075] In one embodiment of the present application, the shape of the covering sleeve conventional in the industry is taken as an example to illustrate the entire shape of the covering sleeve. Figure 3 As shown, the shape of the covering sleeve is a barrel-shaped structure with one end open and the other end closed; specifically, the covering sleeve includes an outer covering sleeve 1 with a barrel-shaped structure having a pre-buried wire groove and an inner protective layer 2 located inside the outer covering sleeve; the wire pre-buried groove 3 is an L-shaped structure as a whole (that is, with the center line of the outer covering sleeve 1 as a reference, the wire pre-buried groove 3 is arranged along the length direction of the outer covering sleeve, the wire pre-buried groove 3 is located on the side wall of one side of the outer covering sleeve, one end of the wire pre-buried groove 3 is located at the open end of the side wall, and the other end is located at the center of the closed end of the outer covering sleeve) to achieve the fixation of the positions of the two ends of the wire 4.

[0076] Furthermore, the external force factors acting on the wire in the cross-sectional direction and the length direction include: the wire is squeezed by the external force in the cross-sectional direction, the expansion, contraction or bending in the cross-sectional direction due to temperature changes, and the change in the length of the wire caused by the stretching, compression or vibration of the wire in the length direction.

[0077] A method for forming a pre-buried wire sheath, the method comprising:

[0078] S1, using insulating rubber to prepare an outer sheath having a serpentine-shaped wire pre-buried groove, wherein the wire pre-buried groove is provided on the inner wall of the outer sheath along the extension direction of the outer sheath;

[0079] S2, treating the surface of the conductor embedded groove to obtain a good bonding interface;

[0080] S3, fixing the wire in the wire embedded groove, with both ends of the wire located outside the ends of the outer sheath;

[0081] S4, covering and fixing the inner protective layer on the side of the conductor facing away from the conductor embedded groove;

[0082] S5, preparing a pre-buried wire covering sleeve by vulcanizing the inner protective layer, the wire, and the outer covering sleeve.

[0083] Furthermore, the rubber used to prepare the outer covering is made of the same material as that of the inner protective layer.

[0084] It should be noted that:

[0085] In the present application, an outer sheath of a wire pre-buried groove having a serpentine shape is prepared by using insulating rubber, which is used to support and provide an outer sheath with a uniform thickness and safe installation space for the wire; by fixing the wire in the wire pre-buried groove, the two ends of the wire are located outside the two ends of the outer sheath, thereby ensuring that the length direction of the wire meets the design requirements; in addition, by covering and fixing the inner protective layer on the side of the wire facing away from the wire pre-buried groove; the inner protective layer, the wire, and the outer sheath are subjected to a vulcanization process to prepare a pre-buried wire sheath, through this process, a pre-buried sheath is provided with a uniform thickness of the wire from the outer wall of the sheath, a controllable deformation space of the pre-buried wire in the cross-sectional direction and the length direction of the wire, and a pre-buried sheath that ensures that the distance between the wire and the outer wall of the sheath is always within a safe distance range during the molding process;

[0086] In order to prevent excessive external force on the side of the wire facing the inner protective layer during vulcanization, in one embodiment of the present application, an air bag 5 is stuffed into the inner protective layer to perform vulcanization;

[0087] In the present application, the inner protective layer is a shaped or sheet-shaped thermal insulation rubber, the length of which matches the size of the wire embedded groove and the width of which is greater than the maximum groove width of the wire embedded groove;

[0088] The insulating rubber used to prepare the outer sheath and the insulating rubber used to prepare the inner protective layer are any one of EPDM rubber, nitrile rubber and silicone rubber. The rubber used to prepare the outer sheath and the insulating rubber used to prepare the inner protective layer are made of the same material, which provides a guarantee for the stability of the performance of the entire sheath.

[0089] The specific preparation process of the pre-embedded coating sleeve is as follows:

[0090] 1) Structural design of embedded covering:

[0091] like Figure 1As shown, the pre-buried wire covering sleeve described in the present application consists of two parts: a covering sleeve wire with thermal insulation performance, wherein the covering sleeve includes an inner protective layer 2 and an outer covering sleeve 1, and the inner wall of the outer covering sleeve 1 facing the inner protective layer 2 is provided with a wire pre-buried groove 3 similar to a snake; the groove width of the wire pre-buried groove 3 is determined according to the width of the wire; the wire 4 is placed in the wire pre-buried groove 3, and the width of the wire 4 is determined according to the design requirements; the inner protective layer 2 covers the side of the wire 4 facing away from the wire pre-buried groove, and the inner protective layer and the outer covering sleeve 1 provided with the wire pre-buried groove 3 constitute a wire pre-buried cavity (insulating cavity) of the wire 4, wrapping the wire inside.

[0092] 2) Designing and preparing a preforming mold for the outer covering according to the shape of the outer covering;

[0093] The preforming mold is a male-female mold or a half-and-half mold structure, which matches the shape of the outer sheath 1 , and the wire embedded groove in the preforming mold is a serpentine structure.

[0094] 3) Clean the preforming mold and preheat it on a flat vulcanizer or hydraulic press. The preheating temperature of the preforming mold is 80℃~100℃ and the temperature should be kept for at least 1 hour.

[0095] Then, the weighed insulating rubber is placed in a pre-forming mold and pressed to prepare an outer sheath having a wire embedded groove with a serpentine structure on the inside;

[0096] Among them, the pressing parameters are: closing the mold without pressurization and keeping warm for 10min to 20min; then pressurizing at a pressure of 80MPa / cm 2 ~100MPa / cm 2 At the same time, the temperature is raised from the preheating temperature to 140℃~150℃ over 1h, kept warm for 1h~3h, then the heating is turned off, the pressure is maintained and the temperature is lowered to 60℃~80℃ for demoulding.

[0097] 5) Take out the product to check whether the appearance and relevant dimensions meet the design requirements.

[0098] 6) If Figure 4 As shown, the wire pre-embedded groove 3 is treated (the treatment method includes but is not limited to grinding or sandblasting) to provide a good bonding interface. After applying adhesive to the wire pre-embedded groove 3, the prepared wire 4 is placed into the wire pre-embedded groove 3. Adhesive is also applied to the surface of the wire 4 outside the wire pre-embedded groove 3. The inner protective layer 2 is then attached to the outside of the wire pre-embedded groove 3, encasing the wire 4.

[0099] 7) Place the pasted outer sheath 1, wire 4 and inner protective layer 2 into the vulcanization tooling. The wires 4 reserved outside the front and rear should extend out of the tooling to be free. Place the airbag 5 inside the entire sheath formed by the inner protective layer 2 and the outer sheath 1. After assembly, vulcanization is carried out.

[0100] The vulcanization process (procedure) is as follows: heating from room temperature to 120°C over 2 hours, keeping warm for 1 hour; then heating to 150°C to 160°C over 1 hour, keeping warm for 2 hours to 4 hours; after the end of the keeping warm, the pressure is maintained at 80 MPa / cm 2 ~100MPa / cm 2 , cool to 60℃.

[0101] 8) Disassemble the tooling, take out the product, inspect its appearance and dimensions, and perform a continuity test on the wires.

[0102] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0103] Example 1:

[0104] The pre-buried wire sheath prepared in this embodiment is used for the dual-pulse propellant of a dual-pulse engine. The wire within the pre-buried wire sheath is safe and reliable, with a diameter of 1.5 mm. The sheath has an outer diameter of 300 mm, a length of 550 mm, and a thickness of 2 mm. The insulating material used in this embodiment is nitrile rubber. The specific preparation process is as follows:

[0105] (1) Design of the covering structure:

[0106] The wire covering sleeve includes a covering sleeve with heat insulation performance and a wire, wherein the covering sleeve includes an outer covering sleeve with a wire embedded groove on the inner wall of one side and an inner protective layer covering the outside of the wire embedded groove; the wire is located in the wire embedded groove.

[0107] The distance between the wire embedded groove and the outer wall of the outer sheath is 2mm. The structure of the wire embedded groove is a serpentine groove body arranged in an S shape along the extension direction of the outer sheath. The groove width of the wire embedded groove is 5mm; the thickness of the outer sheath is 2mm.

[0108] (2) Preparation of outer covering:

[0109] a) Prepare the pre-molding mold of the outer sheath according to the structural design of the outer sheath. It is generally a male-female mold or a half-and-half mold structure according to the size. The wire embedded groove is a groove body with a structure similar to a snake, such as Figure 3 shown.

[0110] b) Clean the preforming mold and preheat it on a flat vulcanizer or hydraulic press at 100°C for at least 1 hour;

[0111] c) Then, the weighed NBR insulation material is placed into the preformed mold and pressed. Pressing parameters: close the mold and keep warm for 20 minutes without pressurizing; then pressurize at a pressure of 100 MPa / cm 2 At the same time, the temperature is raised from the preheating temperature to 150°C over 1 hour, kept warm for 2 hours, then the heating is turned off, the pressure is maintained and the temperature is lowered to 60°C for demoulding.

[0112] d) Take out the product to check whether the appearance and relevant dimensions meet the design requirements.

[0113] e) The conductor pre-embedded trough is then polished or sandblasted to achieve a good bonding interface. After applying adhesive, the prepared conductors are placed into the serpentine-shaped conductor pre-embedded trough, also applying adhesive to the conductor surface. A raw rubber strip with an inner protective layer of nitrile rubber is then applied to the conductor pre-embedded trough, wrapping the conductor inside. Adhesive is then applied to the contact surface between the raw rubber strip and the conductor.

[0114] f) Place the bonded outer sheath, conductors, and inner protective layer into the vulcanization equipment. The conductors left outside the pre-embedded conductor slots should be free and extend out of the preform mold. Then, insert the airbag inside the sheath formed by the inner protective layer and outer sheath. Once assembled, proceed to vulcanization. Vulcanization procedure: Raise the temperature from room temperature to 120°C over 2 hours, hold at this temperature for 1 hour, then raise the temperature to 160°C over 1 hour, hold at this temperature for 2 hours. After holding at this temperature, maintain pressure and cool down to 60°C.

[0115] g) Disassemble the tooling, take out the product, inspect its appearance and dimensions, and perform a continuity test on the wires.

[0116] Example 2:

[0117] The pre-buried wire sheath involved in this embodiment is used for solid rocket engine propellant, requiring the wire to be safe and reliable. The wire diameter is 2mm; the sheath has an outer diameter of 220mm, a length of 600mm, and a thickness of 3mm. The material is EPDM rubber insulation material. The preparation process is as follows:

[0118] (1) Design of the covering structure

[0119] The pre-buried covering sleeve includes a covering sleeve with heat insulation performance and a conductor, wherein the covering sleeve includes an outer covering sleeve with a conductor pre-buried groove on the inner wall of one side and an inner protective layer covering the outside of the conductor pre-buried groove; the conductor is located in the conductor pre-buried groove.

[0120] The distance between the wire embedded groove and the outer wall of the outer sheath is 1.5mm. The structure inside the wire embedded groove is a serpentine groove body with a groove width of 7mm; the thickness of the sheath is 3mm.

[0121] (2) Preparation of outer covering:

[0122] a) Prepare the pre-molding mold of the outer sheath according to the structural design of the outer sheath. It is generally a male-female mold or a half-and-half mold structure according to the size. The wire embedded groove is a serpentine structure groove, such as Figure 3 shown.

[0123] b) Clean the preforming mold and preheat it on a flat vulcanizer or hydraulic press at 100°C for at least 1 hour;

[0124] c) Then, the weighed EPDM rubber insulation material is placed into the pre-molding mold and pressed. Pressing parameters: close the mold and keep warm for 20 minutes without pressurizing; then pressurize at a pressure of 100 MPa / cm 2 At the same time, the temperature is raised from the preheating temperature to 160°C over 1 hour, kept warm for 2 hours, then the heating is turned off, the pressure is maintained and the temperature is lowered to 80°C for demoulding.

[0125] d) Take out the product to check whether its appearance and relevant dimensions meet the design requirements.

[0126] e) The conductor pre-embedded groove is then polished or sandblasted to create a good bonding interface. After applying adhesive, the prepared conductors are placed into the "snake-shaped" conductor pre-embedded groove, and adhesive is also applied to the conductor surface. The EPDM rubber inner protective layer is then applied to the conductor pre-embedded groove, wrapping the conductor inside. Adhesive is then applied to the contact surface between the rubber strip and the conductor.

[0127] f) Place the bonded outer sheath, conductor, and inner protective layer into the vulcanization equipment. The conductors left outside the pre-embedded conductor slots at both ends should be free and extend from the preform mold. Then, insert the airbag inside the sleeve formed by the inner protective layer and outer sheath. Once assembled, proceed to vulcanization. Vulcanization procedure: Raise the temperature from room temperature to 120°C over 2 hours, hold at this temperature for 1 hour, then raise the temperature to 160°C over 1 hour, hold at this temperature for 3 hours. After the holding period, maintain pressure and cool down to 60°C.

[0128] g) Disassemble the tooling, take out the product, inspect its appearance and dimensions, and perform a continuity test on the wires.

Claims

1. A pre-buried wire sheath, characterized in that: The wire covering sleeve comprises a covering sleeve and a wire; The sheath is provided with a wire pre-buried cavity which provides a controllable deformation space for the wire in the cross-sectional direction and the length direction, and ensures that the distance between the wire and the outer wall of the sheath is always within a safe distance range; The safety distance range refers to the maximum distance between the conductor and the outer wall of the sheath that meets the installation requirements of the conductor sheath. The minimum distance between the conductor and the outer wall of the sheath is greater than the pressure-resistant thickness during molding and the temperature-resistant thickness under high-temperature conditions; The wire is located in the wire embedded cavity; The deformation space is configured to provide a space to protect the conductor within a controllable range when the conductor is subjected to external forces in the cross-sectional direction and the length direction based on the conductor pre-buried groove; The lateral boundary of the controllable range space is determined by the deformation of the conductor's diameter in the cross-sectional direction, and the longitudinal boundary of the controllable range space is determined by the total length of the conductor and the dynamic displacement of the conductor during operation. The wire pre-buried cavity is a hollow cavity formed by the wire pre-buried groove arranged on the inner wall of the outer sheath and the inner protective layer covering the wire pre-buried groove; The wire pre-buried groove is arranged along the extension direction of the outer covering sleeve and is integrally formed with the outer covering sleeve. Provide placement paths and deformation space for wires; After the wires are laid in the wire pre-buried grooves, the inner protective layer is formed integrally with the outer covering sleeve and the wires.

2. The pre-buried wire sheath according to claim 1, characterized in that: The distance between the wire embedded groove and the outer wall of the outer covering sleeve is determined according to the size of the deformation space and the overall thickness of the outer covering sleeve. The width of the wire embedded groove is determined according to the diameter of the wire. The length of the wire embedded groove is determined according to the length of the wire and design requirements.

3. The pre-buried wire sheath according to claim 1, characterized in that: The conductor pre-buried slot is in a serpentine shape formed by continuous periodic or non-periodic bending units; The difference in lateral width of the periodic or non-periodic bending units is less than 0.2 mm.

4. The pre-buried wire covering sleeve according to claim 1, characterized in that: The external forces acting on the conductor in the cross-sectional and longitudinal directions include: the conductor being squeezed by external forces in the cross-sectional direction, the expansion, contraction or bending in the cross-sectional direction due to temperature changes, and the change in the conductor length caused by the stretching, compression or vibration of the conductor in the longitudinal direction.

5. A method for forming a pre-buried wire sheath, characterized in that: The molding method is applied to the preparation of a pre-buried wire sheath according to any one of claims 1 to 4, and the molding method comprises: S1, using thermal insulation rubber to prepare an outer sheath having a wire embedded groove, wherein the wire embedded groove is provided on the inner wall of the outer sheath along the extension direction of the outer sheath; S2, treating the surface of the conductor embedded groove to obtain a good bonding interface; S3, fixing the wire in the wire embedded groove, with both ends of the wire located outside the ends of the outer sheath; S4, covering and fixing the inner protective layer on the side of the conductor facing away from the conductor embedded groove; S5, preparing a pre-buried wire covering sleeve by vulcanizing the inner protective layer, the wire and the outer covering sleeve.

6. A method for forming a pre-buried wire sheath according to claim 5, characterized in that: The heat-insulating rubber used to prepare the outer covering is made of the same material as that of the inner protective layer.

7. A method for forming a pre-buried wire sheath according to claim 5, characterized in that: The vulcanization process is: First, the temperature was raised from room temperature to 120 °C over 2 h and kept at this temperature for 1 h; Afterwards, the temperature was raised from 120°C to 160°C in 1 h and kept at this temperature for 2 h; Finally, after the heat preservation is completed, the temperature is lowered to 60℃ and the pressure is maintained at 80MPa / cm 2 ~100MPa / cm 2 .

8. The method for forming a pre-buried wire sheath according to claim 5, characterized in that: In S1, the process of preparing the outer covering is as follows: 1) Preheat the outer covering mold. The preheating temperature of the outer covering mold is 100°C and kept warm for at least 1 hour; 2) Place the weighed insulation rubber into the preheated outer covering mold and press it; 3) Curing after mold closing; 4) After demoulding, an outer covering sleeve with a serpentine-shaped wire embedded groove on the inside is obtained.

9. A method for forming a pre-buried wire sheath according to claim 8, characterized in that: The curing process is: First, after closing the mold, keep it warm for 20 minutes without applying pressure; Then, pressurize to 100 MPa / cm 2 At the same time, the temperature is raised from the preheating temperature to 150°C over 1 hour and kept warm for 2 hours; finally, the heating is stopped, the pressure is maintained and the temperature is lowered to 60°C to complete the curing.

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