Abstract
In the field of journal bearings, the microtexture processing technology of the bush inner surface has become an effective way to improve the performance of journal bearing. The two-dimensional finite element model of microtexture surface with different shapes of friction pairs is established based on the Navier–Stokes (N-S) equation, and the effect of lubrication conditions on the frictional performance of friction pairs is analyzed. Four microtextures that are radial grooves, circular pits, local reticulation, and circumferential grooved microtexture are processed by laser microcarving on the surface of specimen, and three different lubricating medium conditions are set up with high-viscosity oil, low-viscosity oil, and oil–solid mixture, and the effect of lubrication condition and texture shape on the wear reduction of the microtexture friction pair is studied. Results show that the concave microtexture and the radial groove can improve effectively the friction performance of the friction pair. The microtexture can effectively store the lubricating medium and wear abrasive particles in the mixed lubrication, and avoid effectively the second wear, and its average friction coefficient of radial groove microtexture is 22%, 30% lower than that of high- and low-viscosity lubricating media, respectively. Both theory and experiment have proved that the effect of microtexture on high-viscosity lubricant is better than that of low-viscosity lubricant.
Highlights
For improving the performance of journal bearing, the traditional methods mainly include optimization of bearing structure and optimization of lubrication mode.[1,2,3] Surface coating technology has gradually become an effective method to improve bearing performance with the continuous development of precision machining technology.[4,5] The optimization for the structure and lubrication conditions of the journal bearings are limited by the bearing structure and the application conditions
The above experimental results show that radial groove microtexture has better wear resistance, the mixed lubricant can form a stable oil film with smaller shear strength between the upper and lower parts, and the oil film can avoid the direct contact of the rough convex peak on the friction matrix while producing the dynamic pressure effect; the friction process separates the friction matrix effectively and reduces the contact friction coefficient of friction pair
The mechanism of microtexture anti-friction is analyzed from two aspects, on one hand, the hydrodynamic lubrication effect of high-viscosity lubricants is more effective in reducing friction in microtexture friction pairs, for example, the friction coefficient of concave microtexture at high viscosity is about 15% lower than that of low-viscosity; on the other hand, the lubrication effect of oil–solid mixed lubricants is better in the microtexture friction pairs, and the oil–solid mixture in the microtexture concave can be transferred to the contact surface of the friction pair with the extrusion effect and thermal effect of the friction, which can form a composite lubricant film
Summary
For improving the performance of journal bearing, the traditional methods mainly include optimization of bearing structure and optimization of lubrication mode.[1,2,3] Surface coating technology has gradually become an effective method to improve bearing performance with the continuous development of precision machining technology.[4,5] The optimization for the structure and lubrication conditions of the journal bearings are limited by the bearing structure and the application conditions. Advances in Mechanical Engineering of the surface microtexture bearing is improved in both lubrication and tribological properties, compared with the smooth surface of the friction pair. Hua et al.[14] used the friction pair of GCr15 bearing steel in contact with ring and ring as the research object, and studied the friction properties of different lubrication methods, texture densities by orthogonal experiment. Under the condition of four microtexture shapes, and high- and low-viscosity lubricants, the specific influence of microstructure on the tribological properties of friction pairs is discussed. The contact friction pair with ring and ring contact is used to simulate the contact form of journal bearing, and the effectiveness of the surface microtexture to the friction pair performance improvement is verified experimentally, under three lubrication conditions and different microtexture shapes. The maximum depth of triangular microtexture is h0, the trapezoid microtexture depth is h0, the edge length of the bottom is l/2, the radius of the circular microtexture is h0, and the other dimension parameters are the same as that of Figure 1
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