激光沉积成形分区环形扫描路径生成算法
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摘要
为减小激光沉积成形层温度梯度及制件残余应力,结合激光沉积成形金属薄壁件结构的特点,进行了分区环形扫描验证性实验,实验结果表明:采用分区环形扫描路径,可有效减小成形件的残余应力。提出了一种分区环形扫描路径生成算法。为避免扫描线过长引起的翘曲变形,结合激光沉积成形扫描线极限长度,提出了一种基于扫描线极限长度阈值内极值点搜索的分区算法,对独立轮廓组进行分区;针对薄壁件壁厚多变的结构特点,依据壁厚判断的扫描方式优选准则,采用中线扫描与环形扫描相结合的算法,生成分区自适应环形扫描路径;同时为避免扫描环间过渡区的过熔覆,采用端点偏置算法实现扫描环间的平滑过渡连接;最后为减小层面温度梯度和制件残余应力,提出一种基于四色定理的分区扫描顺序优化算法。
Based on the structural characteristics of laser deposition formed metal thin-wall workpieces,the confirmatory test of subarea annular scan is conducted to reduce the temperature gradient of laser deposition formed layers and the residual stress of workpieces.The experimental results show that the usage of subarea annular scan paths can reduce the residual stress of formed parts effectively.An algorithm for generating the subarea annular scan paths is proposed.First,in order to avoid warping deformation caused by the long line scan,a subarea algorithm based on the extreme point search within the scan line limit length threshold is proposed according to the scan line limit length of laser deposition forming,and used for partitioning the independent contour group.Then based on the structural characteristics of thickness-changeable thin-walled workpieces and according to the optimization criterion of wall-thickness,the midline scan and annular scan are combined as an algorithm for the generation of subarea adaptable annular scan paths.Meanwhile,in order to avoid the over-cladding of the transition zone between scan rings,the endpoint offset algorithm is adopted to achieve a smooth transition connection between scan rings.Finally,in order to reduce the temperature gradient of layer surface and the residual stress of workpieces,a sequential optimization algorithm for subarea scan is proposed based on the four-color theorem.
Based on the structural characteristics of laser deposition formed metal thin-wall workpieces,the confirmatory test of subarea annular scan is conducted to reduce the temperature gradient of laser deposition formed layers and the residual stress of workpieces.The experimental results show that the usage of subarea annular scan paths can reduce the residual stress of formed parts effectively.An algorithm for generating the subarea annular scan paths is proposed.First,in order to avoid warping deformation caused by the long line scan,a subarea algorithm based on the extreme point search within the scan line limit length threshold is proposed according to the scan line limit length of laser deposition forming,and used for partitioning the independent contour group.Then based on the structural characteristics of thickness-changeable thin-walled workpieces and according to the optimization criterion of wall-thickness,the midline scan and annular scan are combined as an algorithm for the generation of subarea adaptable annular scan paths.Meanwhile,in order to avoid the over-cladding of the transition zone between scan rings,the endpoint offset algorithm is adopted to achieve a smooth transition connection between scan rings.Finally,in order to reduce the temperature gradient of layer surface and the residual stress of workpieces,a sequential optimization algorithm for subarea scan is proposed based on the four-color theorem.
引文
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[13]Chen J H,Ma P J,Tian J M,et al.Scanning path algorithm for rapid prototyping(RP)based on Voronoi diagrams[J].Mechanical Science and Technology,2003,22(5):728-731.陈剑虹,马鹏举,田杰谟,等.基于Voronoi图的快速成型扫描路径生成算法研究[J].机械科学与技术,2003,22(5):728-731.
[14]Guo L G.Pseudo four-color algorithm research based on the four color principle[J].Digital Technology and Application,2017,35(3):159-160.郭林庚.基于四色原理技术的伪四色算法研究[J].数字技术与应用,2017,35(3):159-160.
[15]Wang J W,Dai G M,Xie B Q,et al.A survey of solving the traveling salesman problem[J].Computer Engineering&Science,2008,30(2):72-74,155.王剑文,戴光明,谢柏桥,等.求解TSP问题算法综述[J].计算机工程与科学,2008,30(2):72-74,155.
[16]Jia D,Zhang X.Application and limit of greedy approach in algorithm design[J].Journal of Liaoning Teachers College(Natural Science Edition),2015,17(3):1-4,74.贾丹,张兴.贪婪法在算法设计中的应用与局限[J].辽宁师专学报(自然科学版),2015,17(3):1-4,74.
[2]Bian H Y,Liu W J,Wang T R,et al.Scanning mode for laser metal deposition shaping[J].Chinese Journal of Mechanical Engineering,2006,42(10):170-175.卞宏友,刘伟军,王天然,等.激光金属沉积成形的扫描方式[J].机械工程学报,2006,42(10):170-175.
[3]Shang X F,Liu W J,Wang T R,et al.Scanning mode of the metal powder laser shaping[J].Chinese Journal of Mechanical Engineering,2005,41(7):99-102.尚晓峰,刘伟军,王天然,等.金属粉末激光成形扫描方式[J].机械工程学报,2005,41(7):99-102.
[4]Liu B,Zhang Z,Sun Y M,et al.The algorithm of OFFSET hatch in rapid prototyping&manufacturing system[J].Journal of South China University of Technology(Natural Science Edition),2001,29(3):64-66.刘斌,张征,孙延明,等.快速成型系统中OFFSET型填充算法[J].华南理工大学学报(自然科学版),2001,29(3):64-66.
[5]Doan T,Li D C,Lu B H,et al.Effect of scanning methods on the cracking of the DZ125Lsuperalloy in laser direct metal forming[J].Chinese Journal of Lasers,2012,39(10):1003002.Doan Tatkhoa,李涤尘,卢秉恒,等.扫描方式对激光金属直接成形DZ125L高温合金薄壁件开裂的影响[J].中国激光,2012,39(10):1003002.
[6]Bian H Y,Liu W J,Wang T R,et al.New concave polygon convex decomposition algorithm for rapid prototyping subarea scanning[J].Computer Applications,2005,25(9):2143-2145.卞宏友,刘伟军,王天然,等.面向快速制造扫描分区的凹多边形凸分解算法[J].计算机应用,2005,25(9):2143-2145.
[7]Wan L,Wang S Q,Zhang X W,et al.Research on forming quality of selective laser melting titanium alloy based on partition scanning[J].Laser&Optoelectronics Progress,2018,55(9):091401.万乐,王思琦,张晓伟,等.基于分区扫描的选区激光熔化钛合金成形质量研究[J].激光与光电子学进展,2018,55(9):091401.
[8]Wang W,He Y,Qin L Y,et al.Separate area scanning path planning of coaxial powder feeding laser deposition manufacturing[J].Applied Laser,2016,36(4):373-378.王伟,何妍,钦兰云,等.同轴送粉式激光沉积制造分区扫描路径规划[J].应用激光,2016,36(4):373-378.
[9]Yang G,Zhou J P,Qin L Y,et al.Influence of separate area scanning on the temperature field of laser deposition manufacturing of titanium alloy[J].Applied Laser,2015,35(4):428-436.杨光,周佳平,钦兰云,等.分区扫描对激光沉积制造钛合金温度场的影响[J].应用激光,2015,35(4):428-436.
[10]Bian H Y,Dong W Q,Wang S J,et al.Experimental study on laser deposition repair of surface damage of GH4169thin-walled components[J].Chinese Journal of Lasers,2016,43(10):1002002.卞宏友,董文启,王世杰,等.GH4169薄壁零件表面损伤的激光沉积修复试验研究[J].中国激光,2016,43(10):1002002.
[11]Shi Y S,Zhong Q,Chen X B,et al.Research and implement of a new kind of scanning mode for selective laser sintering[J].Chinese Journal of Mechanical Engineering,2002,38(2):35-39.史玉升,钟庆,陈学彬,等.选择性激光烧结新型扫描方式的研究及实现[J].机械工程学报,2002,38(2):35-39.
[12]Chen H,Wang X M,Jiao Y S,et al.An optimal algorithm for calculating the width of convex polygons[J].Journal of Engineering Graphics,2011,32(2):5-9.陈海,王新民,焦裕松,等.一种求凸多边形宽度的优化算法[J].工程图学学报,2011,32(2):5-9.
[13]Chen J H,Ma P J,Tian J M,et al.Scanning path algorithm for rapid prototyping(RP)based on Voronoi diagrams[J].Mechanical Science and Technology,2003,22(5):728-731.陈剑虹,马鹏举,田杰谟,等.基于Voronoi图的快速成型扫描路径生成算法研究[J].机械科学与技术,2003,22(5):728-731.
[14]Guo L G.Pseudo four-color algorithm research based on the four color principle[J].Digital Technology and Application,2017,35(3):159-160.郭林庚.基于四色原理技术的伪四色算法研究[J].数字技术与应用,2017,35(3):159-160.
[15]Wang J W,Dai G M,Xie B Q,et al.A survey of solving the traveling salesman problem[J].Computer Engineering&Science,2008,30(2):72-74,155.王剑文,戴光明,谢柏桥,等.求解TSP问题算法综述[J].计算机工程与科学,2008,30(2):72-74,155.
[16]Jia D,Zhang X.Application and limit of greedy approach in algorithm design[J].Journal of Liaoning Teachers College(Natural Science Edition),2015,17(3):1-4,74.贾丹,张兴.贪婪法在算法设计中的应用与局限[J].辽宁师专学报(自然科学版),2015,17(3):1-4,74.