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CN-121976007-A - Global cold extrusion strengthening method and device based on double-layer superposition of self-lubricating slotted bushing

CN121976007ACN 121976007 ACN121976007 ACN 121976007ACN-121976007-A

Abstract

The application discloses a full-domain cold extrusion strengthening method and device based on double-layer superposition of self-lubricating slotted bushings, and belongs to the technical field of cold extrusion strengthening precision machining. The method comprises the steps of providing a structural member with holes to be reinforced, placing coaxial sleeve boxes of an inner-layer slotted bushing and an outer-layer slotted bushing into holes, arranging slots on the two layers of bushings and circumferentially staggering 180 degrees, pulling an extrusion core rod through an inner hole of the inner-layer slotted bushing in an interference mode, enabling the inner layer to radially expand and extrude the outer layer to expand, and enabling the outer layer to apply uniform extrusion force to the hole wall to realize universe reinforcement. The inner-layer slotted bushing inhibits the outward protrusion of the material at the self-slotting position, and the outer-layer slotted bushing optimizes the strengthening uniformity, so that the mandrel can be prevented from contacting the hole wall, the raised ridge is reduced, the global stress of the hole wall is ensured, the fatigue life of the holed structural member is prolonged, and the strengthening method is suitable for strengthening the holed structural member in the fields of aerospace and the like.

Inventors

  • ZENG XINJING
  • JIANG ZHIHUA
  • LI JUNFU
  • WANG DONGMING
  • YANG PENGTAO

Assignees

  • 成都飞机工业（集团）有限责任公司

Dates

Publication Date
20260505
Application Date
20260120

Claims (10)

  1. 1. The universal cold extrusion strengthening method based on double-layer superposition of the self-lubricating slotted bushing is characterized by comprising the following steps of: Providing a perforated structural member to be reinforced; the double-layer stacked self-lubricating slotting lining device is arranged in a hole of the perforated structural member, wherein the double-layer stacked self-lubricating slotting lining device comprises an inner slotting lining and an outer slotting lining which are coaxially arranged, the inner slotting lining and the outer slotting lining are provided with slots, and the circumferential positions of the slots of the inner slotting lining and the outer slotting lining are staggered by 180 degrees; The extrusion core rod is pulled through the inner hole of the inner slotted bushing in an interference manner, so that the inner slotted bushing radially expands, the outer slotted bushing is extruded to radially expand, and uniform extrusion pressure is applied to the hole wall of the structural member with the hole by the outer slotted bushing, so that global cold extrusion reinforcement is realized; The inner-layer slotting bush is used for inhibiting the outward protruding of materials at the slotting position of the inner-layer slotting bush, and the outer-layer slotting bush is used for uniformly achieving the full-area cold extrusion strengthening effect.
  2. 2. The method of claim 1, wherein the inner slotted liner has a slotted width The slotting width of the outer layer slotting lining is more than or equal to 。
  3. 3. The method of claim 1, wherein the thickness of the inner split liner The thickness of the outer layer slotting lining is greater than or equal to 。
  4. 4. A method according to claim 1 or 3, wherein the thickness of the inner split bush is 60% -70% Of the total thickness of the double-layer stacked self-lubricating slotting bush device, and the thickness of the outer-layer slotting bush Accounting for 30% -40% of the total thickness of the double-layer stacked self-lubricating slotting lining device.
  5. 5. The method of claim 1, wherein the inner surface of the inner slotted liner and the outer slotted liner are each provided with a self-lubricating coating comprising a binder, a lubricant, and a filler.
  6. 6. The method of claim 5, wherein the binder is a polyamideimide resin, the lubricant is molybdenum disulfide, and the filler is a nanoparticle.
  7. 7. The method of claim 5, wherein the self-lubricating coating has a thickness of 8 μm to 20 μm.
  8. 8. A double-layer stacked self-lubricating split bushing device capable of achieving global cold extrusion reinforcement, characterized by comprising: an inner slotted liner having a first slot; The outer-layer slotting bush is coaxially sleeved outside the inner-layer slotting bush and is provided with a second slotting; wherein the first slit and the second slit are staggered 180 degrees in the circumferential direction; the inner layer slotting lining is used for providing mechanical support in the cold extrusion process and inhibiting excessive protruding of materials at the slotting position; the inner surface of the outer slotted liner is provided with a self-lubricating coating for reducing friction and promoting uniform flow of material.
  9. 9. The apparatus of claim 8, further comprising an inner standard inspection mandrel and an outer standard inspection mandrel for inspecting the dimensions of the inner split bushing and the outer split bushing, respectively.
  10. 10. The device of claim 9, wherein the diameter of the inner layer standard inspection mandrel The following calculation formula is satisfied: ; Wherein, the For the diameter of the inner slotted liner, A thickness of the split bush for the inner layer; Diameter of the outer layer standard inspection mandrel The following calculation formula is satisfied: ; Wherein, the For the diameter of the outer slotted liner, The thickness of the sleeve is slit for the outer layer.

Description

Global cold extrusion strengthening method and device based on double-layer superposition of self-lubricating slotted bushing Technical Field The application belongs to the technical field of cold extrusion strengthening precision machining, and particularly relates to a full-area cold extrusion strengthening method and device based on double-layer superposition of self-lubricating slotted bushings. Background In the fields of aerospace, rail transit and the like, kong Bianyi of the perforated structural member is subjected to fatigue crack initiation due to alternating load, and a perforated cold extrusion strengthening process is a key technology for solving the problem, wherein the slotted bushing type cold extrusion process is a mainstream scheme due to simple operation. The method is characterized in that a bushing with circumferential slits is arranged in a hole to be reinforced, the bushing is expanded by interference drawing and extrusion of a core rod, and pressure is applied to the hole wall to introduce residual compressive stress, so that the fatigue life of a structural member with the hole is prolonged. The existing single-layer slotting lining technology has the inherent defects that firstly, the slotting part cannot transmit extrusion force, a strengthening blind area is formed, strengthening distribution around holes is uneven, secondly, materials at the slotting part are unconstrained, a convex ridge is generated on the wall of the hole after extrusion, secondary stress concentration is easy to induce, thirdly, the convex ridge is required to be reamed and removed, residual stress loss is caused, the strengthening effect is attenuated, fourthly, the convex ridge is easy to cause core rod clamping stagnation, the process stability is poor, the friction between the lining and the core rod is large, the cost is high, and the requirement of high-end equipment on structural reliability cannot be met. Disclosure of Invention The application aims to provide a full-domain cold extrusion strengthening method and device based on double-layer superposition of self-lubricating slotted bushings, which can avoid a core rod from directly contacting a hole wall in the cold extrusion strengthening process, reduce the generation of convex ridges, ensure the uniform stress of the whole hole wall and further prolong the fatigue life of a structural member with holes. In order to achieve the above purpose, the application provides a full-domain cold extrusion strengthening method based on double-layer superposition of self-lubricating slotted bushings, which comprises the following steps: Providing a perforated structural member to be reinforced; The double-layer stacked self-lubricating slotting lining device is arranged in a hole of a perforated structural member, wherein the double-layer stacked self-lubricating slotting lining device comprises an inner slotting lining and an outer slotting lining which are coaxially arranged, the inner slotting lining and the outer slotting lining are provided with slots, and the circumferential positions of the slots of the inner slotting lining and the outer slotting lining are staggered by 180 degrees; the extrusion core rod is pulled through the inner hole of the inner slotted bushing in an interference manner, so that the inner slotted bushing radially expands, the outer slotted bushing is extruded to radially expand, uniform extrusion pressure is applied to the hole wall of the structural member with the hole by the outer slotted bushing, and global cold extrusion reinforcement is realized, wherein the inner slotted bushing is used for inhibiting the material at the slotted part from protruding outwards, and the outer slotted bushing is used for uniformly realizing the global cold extrusion reinforcement effect. Further, the slit width of the inner slit linerThe slotting width of the outer slotting lining is greater than or equal to。 Further, the thickness of the inner slotted linerThe thickness of the outer layer slotting lining is greater than or equal to。 Further, the thickness of the inner slotted liner60% -70% Of the total thickness of the double-layer stacked self-lubricating slotted bushing device, and the thickness of the outer slotted bushingAccounting for 30% -40% of the total thickness of the double-layer stacked self-lubricating slotting lining device. Further, the inner surfaces of the inner slotted bushing and the outer slotted bushing are respectively provided with a self-lubricating coating, and the self-lubricating coating comprises a binder, a lubricant, a filler and an organic volatile solvent. The self-lubricating coating comprises 20-30wt% of polyimide adhesive, 15-25wt% of molybdenum disulfide lubricant, 2-8wt% of nanoparticle filler, 20-45wt% of organic volatilizing solvent, viscosity adjustment and volatilization after solidification. The preparation process of the self-lubricating coating comprises the following steps: (1) Adding MoS 2 lubric