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CN-121991740-A - Ultralow-temperature wear-resistant lubricating grease special for robot

CN121991740ACN 121991740 ACN121991740 ACN 121991740ACN-121991740-A

Abstract

The invention belongs to the technical field of lubricating materials, and discloses ultralow-temperature wear-resistant lubricating grease special for robots. The lubricating grease comprises 85% -92% of base oil, 6% -10% of composite thickening agent, 1% -3% of microencapsulated repairing agent and 0.5% -2% of auxiliary additive, wherein the microcapsule has stress response type rupture characteristic, dicyclopentadiene and triethylaluminum are released when local damage occurs, a high-hardness repairing film is formed by in-situ polymerization, the composite thickening agent ensures thixotropic stability in a wide temperature range, and a base oil blending system ensures low viscosity and elasticity at-70 ℃. The invention solves the problem of incapability of up-grind damage caused by membrane embrittlement of traditional lubricating grease at-70 ℃ by constructing a base oil-composite thickening agent-stress response microcapsule trinity bionic lubrication system, avoids ineffective consumption of a repairing agent, and ensures the structural stability of the repairing membrane in subsequent operation. The invention is suitable for application scenes of polar scientific investigation robots, deep space detection mechanical arms, ultra-low Wen Lenglian carrying robots and the like with strict requirements on joint reliability.

Inventors

  • LI YANGUO

Assignees

  • 圣保路石油化工（天津）股份有限公司

Dates

Publication Date
20260508
Application Date
20260116

Claims (10)

  1. 1. The ultralow-temperature wear-resistant lubricating grease special for the robot is characterized by being constructed based on a bionic self-repairing mechanism and comprising the following components in percentage by mass: 85% -92% of base oil, wherein the base oil is a blend of perfluoropolyether and hydrogenated styrene-isoprene block copolymer, and the mass ratio of the base oil to the hydrogenated styrene-isoprene block copolymer is (70:30) - (85:15); 6% -10% of a composite thickening agent; 1% -3% of microencapsulated repairing agent; 0.5% -2% of auxiliary additive.
  2. 2. The ultralow temperature wear-resistant grease for robots according to claim 1, wherein the perfluoropolyether has a number average molecular weight of 2500, a pour point of less than-80 ℃ and a kinematic viscosity of 80mm 2 /s at 40 ℃.
  3. 3. The ultra-low temperature wear-resistant grease for robots according to claim 1, wherein the hydrogenated styrene-isoprene block copolymer has a styrene content of 28% and a Tg of-65 ℃.
  4. 4. The ultralow-temperature wear-resistant lubricating grease special for robots, according to claim 1, is characterized in that the composite thickening agent is formed by compounding 12-lithium hydroxystearate and fluorinated modified montmorillonite according to the mass ratio of (4:1) - (6:1).
  5. 5. The ultralow temperature wear-resistant lubricating grease special for robots according to claim 4, wherein the fluorinated modified montmorillonite is subjected to hexadecyl trimethyl ammonium bromide intercalation treatment and is subjected to surface modification by a fluorosilane coupling agent.
  6. 6. The ultralow temperature wear-resistant lubricating grease special for robots according to claim 1, wherein the microencapsulated repairing agent is a microsphere with a core-shell structure, the core is a 1:1 molar ratio mixture of dicyclopentadiene and triethylaluminum, and the shell is a urea resin and nano silicon dioxide hybrid crosslinked network.
  7. 7. The ultralow temperature wear-resistant lubricating grease special for robots according to claim 1, wherein the standard deviation of particle size distribution of the microencapsulated repairing agent is less than 2 μm, the thickness of a polydicyclopentadiene repairing film generated by the repairing agent released after the microencapsulated repairing agent is broken on the metal surface is 200-500nm within 30 seconds, the hardness is 0.8-1.2GPa, and the friction coefficient is lower than 0.08.
  8. 8. The ultra-low temperature wear-resistant grease for robots according to claim 1, wherein the auxiliary additive comprises 0.3% of 2, 6-di-tert-butyl-p-cresol, 0.1% of N, N' -bis (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexamethylenediamine and 0.6% of fumed silica.
  9. 9. The ultralow temperature wear-resistant lubricating grease special for robots according to claim 1, wherein Fe 3 O 4 magnetic nanoparticles are doped in a shell layer of the microencapsulated repairing agent, the particle size is 8-12nm, and the doping concentration is 0.5% of the mass of the shell layer.
  10. 10. The ultra-low temperature wear-resistant lubricating grease for robots according to claim 1, wherein the microencapsulated repairing agent adopts a double-layer shell structure, the inner shell is polyurea, the thickness is 0.2 μm, the outer shell is fluorinated polyacrylate, the thickness is 0.15 μm, and the surface energy is 18mN/m.

Description

Ultralow-temperature wear-resistant lubricating grease special for robot Technical Field The invention belongs to the technical field of lubricating materials, and relates to ultralow-temperature wear-resistant lubricating grease special for robots. Background The lubricating grease is used as the interface medium most commonly used in the joint bearing and the transmission mechanism, not only needs to provide basic antifriction and antiwear functions, but also needs to maintain the structural integrity and dynamic repairing capability of the lubricating film under severe temperature change and high-frequency micro-motion load. Although the traditional mineral oil or synthetic hydrocarbon grease has good performance under normal temperature and general low temperature conditions, the molecular chain segments tend to rigidify due to remarkable attenuation of thermal motion in an ultralow temperature environment, so that the viscosity of the base oil is greatly increased, the network of the soap-based thickener is embrittled, and the lubricating film is macroscopically lost in ductility and suddenly reduced in shear strength. The existing lubricating grease system is mostly dependent on a physical adsorption or boundary film forming mechanism to form a protective layer, and once the film layer is subjected to microscopic fracture due to uneven instantaneous impact load or cold start friction heat, in-situ regeneration cannot be realized due to lack of an effective substance transport and chemical response mechanism. In the continuous operation process of the robot, the local dry friction area can be rapidly enlarged, and the micro-point welding and the furrow effect of the contact surface are caused, so that the joint torque fluctuation, the positioning accuracy drift and the sudden clamping stagnation are caused. The failure mode of more traditional greases is highly covert-initial wear often has no obvious sign, and critical components have been irreversibly damaged when the fault appears, which is particularly dangerous in unattended or remote operation scenarios. In recent years, although the film strength is enhanced by adding nano particles or extreme pressure additives, such methods are prone to cause degradation of dispersion stability or catalytic side reactions at ultra-low temperatures, which in turn exacerbates the complexity and uncertainty of the lubrication system. Biological tissues (such as skin and blood vessels) in nature can trigger cascade biochemical reaction through endogenous repair factors after being damaged to realize autonomous recovery of structure and function, and the mechanism provides an all-new direction for intelligent evolution of lubricating materials. Disclosure of Invention In order to achieve the aim of the invention, the invention provides the ultralow-temperature wear-resistant lubricating grease special for the robot, which is constructed based on a bionic self-repairing mechanism, and the microcapsule repairing agent with stress response type rupture characteristic is embedded in the base oil-thickener composite system, so that the lubricating film can trigger endogenous chemical repairing reaction when being subjected to micro damage under the ultralow-temperature working condition, and a protective interface with complete bearing capacity is reconstructed in situ, thereby remarkably improving the operation reliability, fretting wear resistance and failure precursor sensing capacity of the robot joint in a wide temperature range from-70 ℃ to 25 ℃. The lubricating grease comprises, by mass, 85% -92% of base oil, 6% -10% of a composite thickening agent, 1% -3% of a microencapsulated repairing agent and 0.5% -2% of an auxiliary additive. The components cooperate to form a multi-level lubrication structure with dynamic damage response and autonomous repair functions. The base oil is a blend of perfluoropolyether and hydrogenated styrene-isoprene block copolymer in a mass ratio of (70:30) to (85:15). The hydrogenated styrene-isoprene segmented copolymer has the advantages of having a number average molecular weight of 2500, a pour point of lower than-80 ℃, an kinematic viscosity of 80mm 2/s at 40 ℃, excellent low-temperature fluidity and chemical inertness, having a styrene content of 28 percent, a Tg of-65 ℃ and still maintaining rubbery elasticity at-70 ℃, being capable of effectively inhibiting viscosity mutation of base oil at extremely low temperature and providing a flexible dispersion medium for microcapsules. After the two materials are blended, the apparent viscosity at the temperature of-70 ℃ is controlled within 12000 mPa.s, and the low starting torque requirement of the robot joint is met. The composite thickening agent is prepared by compounding 12-lithium hydroxystearate and fluorinated modified montmorillonite according to the mass ratio of (4:1) to (6:1). The 12-hydroxy lithium stearate is used as a main thickener to form a three-dimensional fiber networ