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CN-121702228-B - Fragile front cover of transmitting cylinder, preparation method and testing system comprising fragile front cover

CN121702228BCN 121702228 BCN121702228 BCN 121702228BCN-121702228-B

Abstract

The invention discloses a fragile front cover of a transmitting cylinder, a preparation method and a testing system comprising the fragile front cover, wherein the fragile front cover comprises a cover body and a flange part annularly arranged on the periphery of the cover body, at least 3 radial weakening grooves are formed in the front surface of the cover body, annular weakening grooves are formed in the positions, close to the edges, of the back surface of the cover body, the cross sections of the annular weakening grooves are in a single-inclined-plane wedge shape, the annular weakening grooves comprise vertical side walls and inclined side walls, the vertical side walls are vertically connected with the end faces of the flange part, the inclined side walls form an angle a with the end faces of the flange part, and the inclined side walls extend from the bottoms of the annular weakening grooves to the surface of the cover body and meet the vertical side walls to form an oriented crack expansion area, so that cracks preferentially extend along the angle a under the action of load. Through the design of the integrated polyurethane foam combined with the directional crack extension area, the peak value of the actual bursting force is less than or equal to 7kN, and the low impact requirement of the missile fairing is met. The radial weakening grooves on the front face cooperate with the wedge-shaped circumferential weakening grooves on the back face to make the maximum size of the fragments much smaller than the safety threshold.

Inventors

  • YAO SHUJIAN
  • CHEN FEIPENG
  • YUAN KE
  • SUN CHENGMING

Assignees

  • 中南大学

Dates

Publication Date
20260512
Application Date
20260212

Claims (9)

  1. 1. The preparation method of the fragile front cover of the transmitting cylinder is characterized by comprising the following steps of: s1, foaming and molding a polyurethane cavity to manufacture a cover body, wherein the cover body comprises the steps of mould pretreatment, raw material injection and foaming, and density control, The pretreatment of the die, namely uniformly spraying a release agent in advance of the inner cavity of the die, adopting an aqueous release agent to spray the release agent with the thickness of 5-10 mu m, ensuring no leakage or accumulation, and controlling the preheating of the die at 60-70 ℃ so as to eliminate internal stress; Preparing 100 parts of isocyanate, 105 parts of polyol and a foaming agent, mixing 100 parts of isocyanate with 105 parts of polyol and the foaming agent, controlling the stirring speed to be 2000rpm plus or minus 5%, injecting polyurethane raw materials with the material temperature of 20-22 ℃ into a die, and injecting the polyurethane raw materials under the pressure of 0.2-0.3 MPa for no more than 8s, wherein the foaming time is 90-120 s, and maintaining the pressure for 5min to obtain a polyurethane cavity; density control, namely monitoring in real time through an ultrasonic densimeter, and adjusting the foaming pressure to ensure that the density is stabilized at 600+/-10 kg/m < 3 >; demolding, namely demolding for 10-15 min, standing at room temperature for more than 24h, and releasing internal stress; S2, machining a radial weakening groove, a circumferential weakening groove, a crack initiation hole and a flange part by adopting a machining process; s3, product surface processing treatment, including primary polishing of the surface, primary spraying of primer on the surface, scraping of putty, repair polishing of the surface, secondary spraying of primer and spraying of finishing paint; s4, performing a forward pressure bearing test, a reverse pressure bearing test and a bursting force test, if the pressure of the two pressure bearing tests exceeds 0.1MPa, indicating that the product meets the pressure bearing performance requirement, and if the transient bursting force peak value of the product is less than 7kN, indicating that the product is qualified.
  2. 2. The method for preparing a fragile front cover of a transmitting tube according to claim 1, wherein in the step S3, Polishing the surface for the first time, namely polishing the surface of a product smoothly by sand paper, polishing the surface to be rough, and cleaning the demolding wax; spraying a primer on the surface for the first time, namely spraying a product in a paint spray booth for 2 times uniformly, wherein the thickness of a paint film reaches 30-50 mu m, ensuring that the paint surface has no particles and sagging, and drying the product in a drying room for 12h at normal temperature; The putty is scraped, the product is flatly placed, the surface of the rubber area is not scraped, the whole surface of the spliced radian surface is thinly scraped, the thickness is less than 200 mu m, the whole surface is flat and thinly scraped, the thickness is less than 300 mu m, and the surface is flat and free from defects; surface repair and polishing, namely, putty repair product surface defects, wherein the product is integrally polished after the putty is dried, and dust is blown out after polishing is finished; Spraying the primer for the second time, namely spraying the product in a spray booth for 2 times uniformly, wherein the thickness of a paint film reaches 30-50 mu m, so that no particles or sagging on the paint surface are ensured, the set plumpness is achieved, and no sand paper mark is displayed after a dry film; And (3) spraying finishing paint, namely spraying the product in a paint spray booth, wherein the product is uniformly sprayed for 3 times, the thickness of a paint film reaches 40-60 mu m, the glossiness reaches 40-70, and no particles and sagging of the paint surface are ensured.
  3. 3. The fragile front cover of the transmitting cylinder is manufactured by adopting the manufacturing method according to claim 1 or 2 and is characterized by comprising a cover body and a flange part annularly arranged on the periphery of the cover body, wherein at least 3 radial weakening grooves are formed in the front surface of the cover body, the annular weakening grooves are formed in the position, close to the edge, of the back surface of the cover body, the cross section of each annular weakening groove is in a single-inclined-plane wedge shape and comprises a vertical side wall and an inclined side wall, the vertical side wall is vertically connected with the end face of the flange part, the inclined side wall and the end face of the flange part form an angle a, the range of the angle a is 100 degrees < a <150 degrees, and the inclined side wall extends from the bottom of each annular weakening groove to the surface of the cover body and is intersected with the vertical side wall to form an oriented crack expansion area, so that cracks preferentially extend along the angle a under the load effect of impact.
  4. 4. The fragile front cover of the launch tube of claim 3, wherein a crack initiation hole is formed in the center of the cover body, the radial weakening grooves are radially distributed with the crack initiation hole as an origin, and the tail ends of the radial weakening grooves extend to the edge of the cover body.
  5. 5. The fragile front cover of the transmitting tube of claim 3, wherein the number of the radial weakening grooves is 6-12 and the radial weakening grooves are distributed at equal angles, the width of the radial weakening grooves is 1/10-2/15 of the thickness of the cover body, and the depth of the radial weakening grooves is 2/3~3/4 of the thickness of the cover body.
  6. 6. The frangible front cover of claim 3, wherein the circumferential weakening groove has a depth of 2/5~3/5 of the thickness of the cover and the directional crack extension has a thickness of 2/5-3/5 of the thickness of the cover.
  7. 7. The fragile front cover of the transmitting tube of claim 3, wherein the cover body is formed by foaming and integrating a polyurethane cavity, and the density of polyurethane foam materials is controlled to be 580-620 kg/m < 3 >.
  8. 8. The system for testing the fragile front cover of the transmitting cylinder is carried out by adopting the fragile front cover of the transmitting cylinder according to any one of claims 3-7 and is characterized by comprising a control unit, an air source, an air inlet pipeline, an air inlet valve, an air bottle and a pressure container, wherein the air bottle is arranged below the pressure container, the air source is connected with the air bottle through the air inlet pipeline, the air inlet valve is arranged on the air inlet pipeline, the air inlet valve is electrically connected with the control unit, the fragile front cover of the transmitting cylinder is arranged on the upper end face of the pressure container, and a through hole is arranged at the inner bottom of the pressure container.
  9. 9. The frangible front cover testing system of claim 8, further comprising a bursting rod disposed through the through hole and vertically movable along the cylinder, wherein a push plate is disposed at the bottom of the bursting rod.

Description

Fragile front cover of transmitting cylinder, preparation method and testing system comprising fragile front cover Technical Field The invention relates to the technical field of missile launching box covers, in particular to a fragile front cover of a launching tube, a preparation method and a testing system comprising the fragile front cover. Background The fragile front cover of the missile launching barrel needs to meet multiple contradictory requirements under extreme working conditions, not only bears severe storage and transportation environmental pressure, but also is instantaneously crushed by the missile fairing with a bursting force less than or equal to 7kN during launching, and residues after crushing cannot block a missile passage, so that fragments need to be strictly restrained within the range of the inner diameter of the launching barrel. The Chinese patent with the publication number of CN110806151A discloses a missile fragile front cover, which comprises a front cover body provided with a weakening groove and a mooring mechanism used for restraining splashing of the front cover body, wherein the weakening groove is arranged along the radial direction and/or the weft direction of the front cover body to divide the front cover body into a plurality of zones to be broken by the weakening groove, the mooring mechanism is a rope with two ends respectively provided with fixed ends, one end of the mooring mechanism is fixedly connected with the cylinder wall of a missile launching cylinder, and the other end of the mooring mechanism is fixedly connected with the upper end face of the zone to be broken. Through setting up radial and/or latitudinal weakening groove in the front of protecgulum body, make the protecgulum body break after receiving the impact, but the setting of weakening groove only sets up in the front of protecgulum body, and its distribution area is comparatively single to can not produce good crushing effect. The application adopts a hard polyurethane foam plastic and glass fiber cloth or nylon fiber cloth reinforcement scheme to improve the pressure-bearing strength of the front cover, and simultaneously, the actual bursting force is greatly improved, and the low bursting force requirement of missile launching cannot be met; in addition, the multilayer material scheme leads fiber at the edge of the groove to be peeled off and damage the structural integrity due to weak bonding force between material layers when the weakening groove is machined, and the fracture track is randomly deviated due to no crack guiding in actual use, so that the safety threshold of the maximum residual chip inner diameter of the missile launching channel is difficult to be met. Disclosure of Invention In order to solve the defects in the prior art, the invention provides the fragile front cover of the launching tube, which has the advantages that crack guiding fracture tracks are formed, the weakening grooves are widely distributed, residues after crushing cannot obstruct missile channels, and a better crushing effect can be generated. According to the technical scheme, the fragile front cover of the transmitting cylinder comprises a cover body and a flange part annularly arranged on the periphery of the cover body, at least 3 radial weakening grooves are formed in the front face of the cover body, annular weakening grooves are formed in the back face of the cover body, close to the edge, the cross section of each annular weakening groove is in a single-inclined-plane wedge shape and comprises a vertical side wall and an inclined side wall, the vertical side wall is vertically connected with the end face of the flange part, the inclined side wall and the end face of the flange part form an angle a, the range of the angle a is 100 degrees <150 degrees, and the inclined side wall extends from the bottom of each annular weakening groove to the surface of the cover body and is intersected with the vertical side wall to form a directional crack expansion area, so that cracks preferentially extend along the angle a under the action of impact load. Through setting up wedge-shaped hoop weakening groove near edge at the back, hoop weakening groove provides the direction for the crackle, makes the fracture track extend along the angle is priority, and after the fragile lid of churn received the impact, the hoop weakening groove cooperation positive radial weakening groove of back can make the identical fracture of fragile lid, and broken back residue can not hinder the guided missile passageway. In one embodiment, a crack initiation hole is formed in the center of the cover body, the radial weakening grooves are distributed in a radial mode with the crack initiation hole as an origin, and the tail ends of the radial weakening grooves extend to the edge of the cover body. Wherein the depth of the crack initiation hole is equal to the depth of the radial groove, and the diameter of the crack initiation hole is 4