| Gear is one of the most important ways of transmission in machinery industry.It is widely used in aviation, aerospace, transportation, machinery and instrument manufacturing and other industrial sectors,for a number of advantages such as wide range of speed ratio, wide power range, high transmission efficiency, compact structure and reliability.As a result of the cyclical impact, bending stress, contact stress and friction, a combination of those force which the meshing gears bear in the transmission, combined with very poor working condition of gear,the meshing teeth are often failure because of wear and tear , much worse pitting will appear, leading to the unnormal operation of gear,which severely reduces the life of gear.So how to improve the wear resistance and service life of gear is urgent problem currently in the gear industry.There are many methods to improve gear life which is commonly used currently. For example: by changing the material, the use of methods of surface coating, heat treatment methods,changes in processing technology, these methods can be to some extent to improve the life of gear.However, due to the limitations of its own, it is difficult to fundamentally improve the wear-resistant properties of gear fatigue. The emergence of bionics solve these problems well.Bionics study found that some organisms non-smooth form has highly efficient anti-fatigue, wear-resistant.For example,intertidal shellfish biological are under long-term sea water erosion, but they still has hard bright surface.Pangolin and other soil organisms, living in the soil, its surface contacts with soil, rock and other hard material in long-term , but its surface dose not have fatigue, wear and tear marks.This paper was set the inter-tidal shellfish and pangolin reptiles as biological prototype, the biological form of non-smooth surface had been extracted with the help of research results available in the laboratory. Stripe diameter, horizontal stripe spacing and vertical stripes were selected by analysis as effect factors for the trial. And adopting the idea of optimal design, nine pilot programs were designed. They were carved onto the gear to improve the fatigue life and wear resistance.Carried out on the gear contact force analysis, usually using a cylindrical mesh with two parallel lines instead the actual tooth surface location, so we could use a pair of cylindrical roller to replace the gear meshing research.In the paper ,gears were replaced by cylindrical rollers to the preferre surface morphology of biomimetic to simplify testing, reducing the costs. The pre-designed biomimetic was carved onto the specimen with laser engraving machine, the right processing parameters were got after repeated tests, adjustments.The morphology of biomimetic on the specimen surface.was observed with SEM scanning electron microscope an optical microscope and 3D laser scanning confocal microscope . The surface morphology of the biomimetic on the specimen surface fully met the design requirements.In addition, high hardness, small homogeneous surface layer were obtained because of laser processing, thus improving the wear resistance of fatigue specimen.The matrix, the heat-affected zone, fused layer hardness of the laser processed sample were tested with micro-hardness test, knowing that laser processing could improve surface hardness and wear resistance of specimen .The tests were done for rolling sample with M-200 test machine , combined with optimal design theory and orthogonal experimental , the best surface morphology of biomimetic could be chosed.The experimental results showed that the fatigue life and wear resistance of the specimen morphology on the 8th was the best.Biomimetic surface morphology of its parameters: stripe width of 240μm, horizontal stripe spacing of 270μm, stripes vertical spacing of 420μm. Through SEM scanning electron microscope to scan the sample, and sample analysis for wear-resistant mechanism, from the principle that biomimetic patterns of wear specimen is indeed better than the ordinary specimen.The standard gear module on testing machine is 4.5 , but the modulus 4.5 gears are less in the practical application and its manufacturing is not convenient, so the gear was re-designed.The gear was tested with M & M Precision Systems 3000-4QC gear detector , knowing that the precision of the gears could be meet the precision 5.The preferred roller bionic specimen surface parameters were engraved onto a pair of gears with laser engraving machine , and the gears wre tested again, we could see that the laser processed bionic gear still met the precision 5.The bionic gear and general gear wre tested on CL-100 testing machine in the same experimental conditions respectively.Then the gear were observed with microscope-based and analysis and comparison. thegear tooth surface were measured throuth computational of pitting area of one gear.The results showed that the observation area of the scope of 3100817.07um2, Bionic Gear tooth surface pitting of the largest rate of 0.22 percent, the smallest point of corrosion rate of 0.07%; ordinary gear pitting the largest rate of 0.65 percent, the smallest rate of pitting for 0.14%. Bionic pinion pitting the greatest rate of 0.19 percent, the smallest point of corrosion rate of 0.13 percent; ordinary pinion pitting the largest rate of 0.70 percent, the smallest common pinion pitting corrosion rate of 0.26 percent.Proved that the anti-fatigue of bionic gear was better than ordinary gear. The gear pitch error, tooth to the error and profile error detection of bionic and general gear were tested with M & M Precision Systems 3000-4QC gear tester, getting the corresponding error curves and the error value, and the tooth surface for Extension spectral analysis. Proved that the wear resistance of Bionic gear was better than ordinary gear.For an analysis the surface morphology of the bionic Improving gear fatigue life and wear resistance we knew that the pit cells could postpone and block the expansion of crack,so the gear with bionic are less appear the phenomenon of fatigue failure.The compressive stress of Laser machined gear will help to increase of the fatigue life and organization of laser processed materials is more refined and uniform, it has excellent mechanical properties.Its fatigue life and wear resistance is better than that of the conventional quenching gear with the same depth of hardened layer , with the surface area gear with morphology of biomimetic was greater than that of ordinary gear,so lubricating oil failure caused by high temperature can be avoided as well as the thermoplastic deformation caused by the material yield limit lowing result frome high temperature.The pits with biomimetic surface morphology played the role of collection of wear debris and changing wear debris movement state, greatly reduced the abrasive wear phenomenon and helped to improve the fatigue Gear life and wear resistance.In this paper, the fatigue life and wear resistance of gear with surface morphology were studied and analysised, providing a theoretical basis for improving properties of gears in engineering, as well as providing a good example for bionic theory in practical application and laying a certain foundation of bionic gear for practice in the application of engineering. |
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