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YAG激光毛化轧辊微坑分布的评价及加工技术研究
Study on Evaluation and Processing Technologies of Micro-pits Distribution of YAG Laser Texturing Rolls
【作者】 王红才;
【导师】 王扬;
【作者基本信息】 哈尔滨工业大学 , 航空宇航制造工程, 2013, 博士
【摘要】 钢板是应用最广泛的钢材,其中毛化板因特殊的表面形貌使其具有优良的冲压性能和涂镀性能,是汽车工业、家电产业等行业的重要原料。毛化板由毛化轧辊复制而来。轧辊毛化技术就是对磨光轧辊进行毛化,使其表面具有特殊形貌的技术,它是生产毛化板的必备技术。目前工业上得到规模化推广应用的比较先进的轧辊毛化技术是电火花毛化和激光毛化。激光毛化板因其微坑彼此孤立的特殊形貌使其具有比电火花毛化板更优良的冲压和涂镀性能。然而,传统的激光毛化因微坑是一维可控的规则分布,使激光毛化板的延伸率和外观质量等方面的各向均匀性不如电火花毛化板,影响了综合性能。毛化轧辊较理想的微坑分布形式是近似各向均匀的无规则分布。本课题的研究目的就是通过研究YAG激光毛化轧辊近似各向均匀无规则分布微坑的加工技术克服或改善现有激光毛化技术的缺点,提高激光毛化板的综合性能。为了研究表面粗糙度分布的均匀性,本文首先提出了一种表面粗糙度分布的评价方法。提出了三维幅度参数SRa(区域方向性算术平均偏差)、SRq(区域方向性均方根偏差)、SRsk(区域方向性偏斜度)、SRku(区域方向性陡度),建立了相应的区域评价指标、方向评价指标和整体评价指标,为研究表面粗糙度与评价区域、评价方向的定量关系提供了一种依据,为评价幅度参数相对区域、方向和整体的分布提供了一种标准。区域变异系数最小可作为单一评价方向幅度参数分布的区域均匀性评价标准;方向变异系数最小可作为单一评价区域幅度参数分布的方向均匀性评价标准;整体变异系数最小可作为所有评价区域的所有评价方向的幅度参数分布的整体均匀性评价标准。依据方向均匀性评价标准研究了近似各向均匀无规则分布微坑图像设计方法。提出了规则图形排列区域置乱(包括正方形网格排列区域置乱、正方形交错排列区域置乱和正六边形排列区域置乱)、最小间距与最小间距区域置乱等近似各向均匀无规则分布微坑图像设计方法,获得了相应的微坑图像,为在轧辊表面加工多种近似各向均匀无规则分布微坑提供了原始数据。研究了二维可控无规则分布微坑的加工方法。提出了局部位移法(包括无规则延时法和无规则偏转法)与图像法(包括开关法、位移法、开关位移法和开关延时法)等二维可控无规则分布微坑加工方法,为在轧辊表面高效加工多种近似各向均匀无规则分布微坑提供了合适的技术手段。最后,本文研制了基于二维可控无规则分布微坑加工方法的YAG激光毛化轧辊加工系统,开展了YAG激光毛化技术的应用研究。将多种近似各向均匀无规则分布微坑图像成功加工在轧辊表面,实现了预期的目的;将YAG激光毛化技术成功应用于陶瓷网纹辊的激光雕刻,填补了国内空白;还将YAG激光毛化技术成功应用于内燃机缸套内壁激光微造形。与机械珩磨相比,激光刻蚀在降低摩擦系数、减少磨损量方面效果显著。本文提出的表面粗糙度区域方向性幅度参数及其评价指标具有通用性,可用于一般表面粗糙度分布的研究。国家重点科技攻关项目——“冷轧薄钢板激光毛化”的主要目标是开发汽车外覆件用激光毛化板,要解决的一个重要问题是提高激光毛化板的各向均匀性,关键之一是提高激光毛化板微坑分布的各向均匀性。本课题在将毛化板替代进口用于汽车外覆件方面具有重要意义。本课题的应用将为国家节约大量外汇,为企业创造很好的经济效益。
【Abstract】 Steel plate is the most widely used steel products. Texturing sheet, a kind of steelplate, is an important raw material in industries of the automobile, household appliances,etc. It has excellent stamping performance and coating properties due to its specialsurface morphology. It is copied by texturing roll. Roll texturing technology is atechnology which can make burnished roll textured, so the surface of the roll can havespecial surface morphology. This technology is an absolutely necessary technology toproduce texturing sheet. Presently, electrical discharge texturing(EDT) and lasertexturing(LT) are the two kinds of advanced roll texturing technologies which have beenlarge-scale applied in industry.LT steel plate has more excellent stamping performance and coating propertiesthan EDT, because the micro-pits have special surface morphology of isolating eachother by LT. However, because micro-pits are distributed under1D controllable andregular in traditional LT, the isotropic properties of LT steel plate in elongation andappearance quality are worse than EDT, thus lower the comprehensive performance ofLT texturing sheets. The perfect distributed form of micro-pits on texturing rolls isapproximate isotropic and irregular distribution.The study objective of the thesis is to overcome the disadvantages of the existingLT by studying the processing technologies of YAG texturing sheet which micro-pitsare approximate isotropic and irregular distribution. Thus the comprehensiveperformance of YAG texturing sheets can be improved.To study the uniformity of the distribution of surface roughness, the thesis comesup with an evaluation method on the distribution of surface roughness first. The thesisdefines3D height amplitudes of the surface include SRa(area-directional surfacearithmetic mean deviation), SRq(area-directional surface root mean square deviation),SRsk(area-directional surface skewness) and SRku(area-directional surface kurtosis).The thesis also establishes relative assessed area indexes, assessed direction indexes andassessed total indexes. These indexes provide a foundation for studying the quantitativerelation among surface roughness, assessed area and assessed direction. These indexesalso provide a standard for assessing the distribution of the height amplitudes based onarea, direction and total respectively. The minimum of area CV(coefficient of variation)can be used as evaluation criteria of the area-uniformity of the distribution situation onheight amplitudes in a single assessed direction. The minimum of directional CV can beused as evaluation criteria of the direction-uniformity of the distribution situation onheight amplitudes in a single assessed area. The minimum of total CV can be used asevaluation criteria of the uniformity of the total distribution situation on heightamplitudes in all assessed directions of all assessed areae.According to evaluation criteria of the direction-uniformity of the distributionsituation on height amplitudes in a single assessed area, the thesis studies the image design methods of micro-pits with approximate direction-uniformity disordereddistribution. The thesis comes up with some methods: area scrambling micro-pits imagedesign methods based on regular graphics arrangement(include square area scramblingmicro-pits image design methods based on square-aligned-array arrangement andsquare-staggered-array arrangement, and area scrambling micro-pits image designmethod based on equilateral hexagon-array arrangement), minimum interval micro-pitsimage design method, and minimum interval area scrambling micro-pits image designmethod, and acquires relative micro-pits images which provide raw data for processingvarious micro-pits with approximate direction-uniformity disordered distribution onrolls.The thesis studies processing methods for micro-pits with2D controllabledisordered distribution. The thesis comes up with some processing methods formicro-pits with2D controllable disordered distribution including local displacementmethods(including disordered delay method and disordered deflection method) andimage methods(including switch method, displacement method, switch-displacementmethod and switch-delay method). These methods provide proper technical means forprocessing more efficiently various micro-pits with approximate direction-uniformitydisordered distribution on rolls.Finally, the thesis develops a processing system of YAG laser texturing rolls basedon processing methods for micro-pits with2D controllable disordered distribution, andstudies the application of YAG laser texturing technology. The images of micro-pitswith approximate direction-uniformity disordered distribution are processedsuccessfully on the surface of rolls, thus expected goal are reached. YAG laser texturingtechnology is successfully applied on laser engraving of ceramic anilox rolls, thus thedomestic blank is filled. YAG laser texturing technology is also successfully applied onlaser micro-machining of the cylinder sleeve in an internal combustion engine.Compared with mechanical grinding, laser etching has remarkable effect on reducingcoefficient of friction and reducing the amount of wear.Height amplitudes of surface roughness based on area-direction character and theirassessed indexes proposed by the thesis are universal. They can be used to study thedistribution on general surface roughness.The main goal of laser texturing of cold steel sheet, the national key scientific andtechnological project, is to develop laser texturing sheet used on automobile outercladding parts. Its important problem is to improve isotropic character of laser texturingsheet. One of the key is to improve the isotropic character of the distribution ofmicro-pits on laser texturing sheet. The application of the subject will save a largeamount of foreign exchange for the country, and create good economic benefits forenterprises.