| As one of the key components of machine tools, Mechanical properties and Morphology of machine tool slide guide directly influence machining precisions of work pieces and the service life of the machine tool slide guide. Morphology of slide guide surface can be improved by Scraping process, in order to improve contact conditions and friction and wear properties of slide guide surface, but there still exist some disadvantages such as low degree of automation, low processing efficiency. In this thesis, the laser shock processing technology was proposed to treatment process of slide guide surface. 40 Cr steel inlaying steel guide-ways was selected as research object, process exploration and experimental study of laser shocking 40 Cr steel surface were conducted. The main contents were as follows:Effects of laser shock process on surface integrity and wear resistance of 40 Cr machine slide guide surface were analyzed. Analysis suggested that there was greater influence of laser pulse energy, shock times and overlapping rate on surface integrity and wear resistance of 40 Cr surface. During LSP, different laser pulse energy, peak pressure of shock wave on sample surface was different as well, that result in Mechanical properties and Morphology of 40 Cr surface had different degree of change. Shock times on surface by LSP and per unit area of coverage had change with the laser shock time and overlapping rate were different, Mechanical properties and Morphology of 40 Cr surface had different effect of function. From a macro point of view, after LSP, Different degree of plastic deformation was produced, and micro pit was formed on surface. From microcosm, a mass of dislocations, grain sliding and grain refinement were produced on surface layer. These changes from macro perspectives and microcosm had important effect on surface integrity and wear resistance.Influence of LSP on Mechanical properties and Morphology of 40 Cr surface was studied. Changes of residual stress, micro hardness and hardness depth, pit profile and roughness on surface of untreated, scraped and after LSP sample were studied contrastively. Results showed that compared with untreated and scraped sample, residual stress and micro hardness on surface under LSP had been greatly was improved. Shock time and overlapping rate, the residual stress, micro hardness and hardness depth was improved with the increase of laser pulse energy, maximum residual compressive stress value was-460.16 MPa, maximum micro hardness was 412.2HV0.2, hardness depth was closed to 1mm. Depth of pit on surface increased with the increase of laser shock energy and shock time. Conversely, Depth of pit on surface decreased with the increase of overlapping rate. Roughness on surface was improved greatly after LSP; roughness value decreased with the increase of laser shock parameters, minimum roughness vales was 0.25μm.The friction-wear test was carried out on 40 Cr surface after LSP. Wear loss, friction coefficient and worn mechanism were studied. Results showed that wear loss of sample after LSP was less than untreated and scraped sample. Wear loss showed a trend of decrease with the increase of laser pulse energy, shock time and overlapping rate, minimum wear loss was 2.1mg. Compared with untreated and scraped sample, steady friction coefficient of NO.2 sample was around 0.4 and approximately trended to be stable. Analysis of grinding crack surface under different processing condition showed that main types of wear surface were abrasive wear and adhesive wear. There existed grooves and compacted debris in different sizes. The number of grooves and compacted debris on surface of NO.2 sample decreased obviously. It showed that abrasive resistance of sample after LSP was improved significantly. |
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