本文主要研究内容
作者王鑫林（2019）在《三元叶片特征结构的激光直接制造工艺研究》一文中研究指出：三元叶片的传统制造方法往往存在加工难度大,材料去除率高,加工周期长等问题,而且在叶片的扭转角度过大,流道过窄的情况下,极易发生干涉,制造过程面临很大的难度和挑战,甚至无法加工。激光直接制造技术作为一种新型的增材制造技术,可以将复杂的三维空间结构简化为二维平面问题,实现各种高性能、复杂零件的快速、无模具、高致密近净成形,能够缩短加工周期,提高材料利用率,因此,其在三元叶片的研制、制造及修复过程中,有着巨大优势及良好的发展前景。三元叶片悬垂角度大的结构特点和激光直接制造过程中采用的平面分层方式,易引起“阶梯效应”和干涉碰撞,而且三元叶片表面高度和各处悬垂角度的不一致性引起的扫描轨迹、能量输入、熔池冷却速度的差异,将会导致成形出的叶片各个位置存在不一致的微观组织及机械性能,增加了激光直接制造过程控制的难度,而关于其研究却鲜有报道。本文基于三元叶片的结构特点,从激光直接制造工艺参数对于熔覆层几何特征的影响规律出发,针对三元叶片中包含的特征结构,即垂直薄壁结构、斜坡薄壁结构、悬垂薄壁结构,分析特征结构成形的影响因素,结合激光与材料相互作用的原理等分析激光直接制造过程对特征结构的宏微观特征的影响,为三元叶片的激光直接制造奠定基础。本文的主要研究内容和研究成果如下:(1)基于能量和质量守恒定律,建立了不同工艺参数(激光功率、扫描速度、送粉量)条件下熔覆层宽度、高度和深度的预测模型,基于质能量(激光功率与送粉量之比)和线质量(送粉量与扫描速度之比),分析了不同工艺参数水平下模型的预测精度,并且结合Marangoni熔池流动理论,分析了不同工艺参数水平对熔覆层几何特征的影响,结果表明,在工艺参数较小的情况下,激光功率和送粉量对于几何特征的影响更加明显,而在工艺参数较大的情况下,扫描速度的影响更加明显。(2)研究了工艺参数(激光功率、扫描速度、送粉量、能量输入)对垂直薄壁结构组织及机械性能的影响。随着工艺参数的增加,当质能量较大时,熔池冷却速率先减小后增加,晶粒尺寸先增加后减小;当质能量较小时,晶粒尺寸增加,硬度减小。激光直接制造薄壁件的拉伸强度大于传统工艺制造的AISI316L零件,但是伸长率低于传统工艺制造的零件,水平方向的拉伸强度大于竖直方向的拉伸强度。水平方向的拉伸强度随着沉积高度的增加而增加,竖直方向的拉伸强度由边缘到中间位置逐渐增大。在质能量和线质量保持不变的情况下,随着工艺参数的增加,细化的晶粒使得拉伸强度增加。与连续激光相比,由于脉冲激光的能量输入小,因此其制造的薄壁件的组织更加细小,硬度更高,拉伸强度更大,但是伸长率较低。在脉冲激光直接制造过程中,当脉冲间隔相同时,随着脉冲宽度的增加,晶粒尺寸逐渐增大,硬度逐渐减小。当占空比相同时,脉冲宽度越小,薄壁件的硬度越大。采用硬度压痕法,分析了不同激光模式下制造的薄壁件的残余应力分布状态,发现在脉冲激光模式下,中间位置沿沉积高度方向表现为残余拉应力,边缘位置表现为残余压应力,而连续激光制造的薄壁件残余应力分布情况截然相反;在脉冲激光模式下,薄壁件中间位置沿激光扫描方向的残余应力随着位置的不同表现为拉应力和压应力间的周期性变化,而连续激光制造的薄壁件中间位置沿激光扫描方向表现为残余拉应力,边缘位置表现为残余压应力。(3)研究了离焦量和Z轴单层行程(△Z)对于激光直接制造薄壁件的作用规律,以及成形方式对于激光直接制造斜坡薄壁结构的组织性能的影响。离焦量绝对值的增加将导致单层沉积层的高度减小。在激光直接制造中,当△Z在合适范围内时,激光直接制造过程存在负反馈机制,可以达到△Z与单层沉积高度相等的状态,实现稳定的成形。基于此反馈机制,提出3D分层成形方式(同一沉积层不同位置处的AZ不同)制造表面高度不一致的斜坡薄壁结构的方法。采用平面分层和3D分层成形方式制造的斜坡薄壁结构的平均硬度变化不大,但是硬度分布明显不同,前者的拉伸强度和伸长率略大于后者。随着斜坡薄壁结构倾斜角度的增加,平均拉伸强度增加,伸长率减小,拉伸加载方向与晶粒滑移表面的夹角,影响着沿滑移表面的剪应力,对于拉伸强度有着重要的影响,当倾斜角度为20°时,在平面分层和3D分层成形方式下,拉伸加载方向与水平方向夹角分别为45°和25°时,其与滑移表面更加接近于垂直状态,沿滑移表面的剪应力较小,熔池边界可以承受较大的拉伸力,且表现出较大的拉伸强度;当拉伸力的加载方向与水平方向夹角为90°时,拉伸加载方向与滑移表面的夹角较小,沿滑移表面的剪应力较大,更容易达到屈服极限,表现为较小的拉伸强度。(4)研究了扫描方式和Z轴单层行程(△Z)对于激光直接制造悬垂薄壁结构的影响规律,探讨了影响悬垂薄壁结构极限角度的因素。悬垂薄壁结构的成形质量受到扫描方式(单向扫描和往复扫描)和AZ的影响。与单向扫描方式相比,往复扫描方式下成形出的悬垂薄壁结构表面平整且两端对称,成形质量更高。△Z对悬垂薄壁结构的角度精度有着重要的影响,△Z的优化使得实验角度与设计角度的差异大幅减小。然而,悬垂薄壁结构可成形的极限角度只能达到32°左右,△Z的优化无法增加悬垂薄壁结构的极限角度。可成形的悬垂结构的极限角度受到熔池表面张力、粉末流冲击力、重力之间关系的制约,与熔池几何形状和材料特性有关。通过正交实验,得出了不同工艺参数(激光功率、扫描速度和送粉量)条件下,能够保证悬垂薄壁结构较高精度的Z轴单层行程。而且,Z轴单层行程与(P/Qm)1/4(Qm/V)存在正相关的线性关系。
Abstract
san yuan xie pian de chuan tong zhi zao fang fa wang wang cun zai jia gong nan du da ,cai liao qu chu lv gao ,jia gong zhou ji chang deng wen ti ,er ju zai xie pian de niu zhuai jiao du guo da ,liu dao guo zhai de qing kuang xia ,ji yi fa sheng gan she ,zhi zao guo cheng mian lin hen da de nan du he tiao zhan ,shen zhi mo fa jia gong 。ji guang zhi jie zhi zao ji shu zuo wei yi chong xin xing de zeng cai zhi zao ji shu ,ke yi jiang fu za de san wei kong jian jie gou jian hua wei er wei ping mian wen ti ,shi xian ge chong gao xing neng 、fu za ling jian de kuai su 、mo mo ju 、gao zhi mi jin jing cheng xing ,neng gou su duan jia gong zhou ji ,di gao cai liao li yong lv ,yin ci ,ji zai san yuan xie pian de yan zhi 、zhi zao ji xiu fu guo cheng zhong ,you zhao ju da you shi ji liang hao de fa zhan qian jing 。san yuan xie pian xuan chui jiao du da de jie gou te dian he ji guang zhi jie zhi zao guo cheng zhong cai yong de ping mian fen ceng fang shi ,yi yin qi “jie ti xiao ying ”he gan she peng zhuang ,er ju san yuan xie pian biao mian gao du he ge chu xuan chui jiao du de bu yi zhi xing yin qi de sao miao gui ji 、neng liang shu ru 、rong chi leng que su du de cha yi ,jiang hui dao zhi cheng xing chu de xie pian ge ge wei zhi cun zai bu yi zhi de wei guan zu zhi ji ji xie xing neng ,zeng jia le ji guang zhi jie zhi zao guo cheng kong zhi de nan du ,er guan yu ji yan jiu que xian you bao dao 。ben wen ji yu san yuan xie pian de jie gou te dian ,cong ji guang zhi jie zhi zao gong yi can shu dui yu rong fu ceng ji he te zheng de ying xiang gui lv chu fa ,zhen dui san yuan xie pian zhong bao han de te zheng jie gou ,ji chui zhi bao bi jie gou 、xie po bao bi jie gou 、xuan chui bao bi jie gou ,fen xi te zheng jie gou cheng xing de ying xiang yin su ,jie ge ji guang yu cai liao xiang hu zuo yong de yuan li deng fen xi ji guang zhi jie zhi zao guo cheng dui te zheng jie gou de hong wei guan te zheng de ying xiang ,wei san yuan xie pian de ji guang zhi jie zhi zao dian ding ji chu 。ben wen de zhu yao yan jiu nei rong he yan jiu cheng guo ru xia :(1)ji yu neng liang he zhi liang shou heng ding lv ,jian li le bu tong gong yi can shu (ji guang gong lv 、sao miao su du 、song fen liang )tiao jian xia rong fu ceng kuan du 、gao du he shen du de yu ce mo xing ,ji yu zhi neng liang (ji guang gong lv yu song fen liang zhi bi )he xian zhi liang (song fen liang yu sao miao su du zhi bi ),fen xi le bu tong gong yi can shu shui ping xia mo xing de yu ce jing du ,bing ju jie ge Marangonirong chi liu dong li lun ,fen xi le bu tong gong yi can shu shui ping dui rong fu ceng ji he te zheng de ying xiang ,jie guo biao ming ,zai gong yi can shu jiao xiao de qing kuang xia ,ji guang gong lv he song fen liang dui yu ji he te zheng de ying xiang geng jia ming xian ,er zai gong yi can shu jiao da de qing kuang xia ,sao miao su du de ying xiang geng jia ming xian 。(2)yan jiu le gong yi can shu (ji guang gong lv 、sao miao su du 、song fen liang 、neng liang shu ru )dui chui zhi bao bi jie gou zu zhi ji ji xie xing neng de ying xiang 。sui zhao gong yi can shu de zeng jia ,dang zhi neng liang jiao da shi ,rong chi leng que su lv xian jian xiao hou zeng jia ,jing li che cun xian zeng jia hou jian xiao ;dang zhi neng liang jiao xiao shi ,jing li che cun zeng jia ,ying du jian xiao 。ji guang zhi jie zhi zao bao bi jian de la shen jiang du da yu chuan tong gong yi zhi zao de AISI316Lling jian ,dan shi shen chang lv di yu chuan tong gong yi zhi zao de ling jian ,shui ping fang xiang de la shen jiang du da yu shu zhi fang xiang de la shen jiang du 。shui ping fang xiang de la shen jiang du sui zhao chen ji gao du de zeng jia er zeng jia ,shu zhi fang xiang de la shen jiang du you bian yuan dao zhong jian wei zhi zhu jian zeng da 。zai zhi neng liang he xian zhi liang bao chi bu bian de qing kuang xia ,sui zhao gong yi can shu de zeng jia ,xi hua de jing li shi de la shen jiang du zeng jia 。yu lian xu ji guang xiang bi ,you yu mai chong ji guang de neng liang shu ru xiao ,yin ci ji zhi zao de bao bi jian de zu zhi geng jia xi xiao ,ying du geng gao ,la shen jiang du geng da ,dan shi shen chang lv jiao di 。zai mai chong ji guang zhi jie zhi zao guo cheng zhong ,dang mai chong jian ge xiang tong shi ,sui zhao mai chong kuan du de zeng jia ,jing li che cun zhu jian zeng da ,ying du zhu jian jian xiao 。dang zhan kong bi xiang tong shi ,mai chong kuan du yue xiao ,bao bi jian de ying du yue da 。cai yong ying du ya hen fa ,fen xi le bu tong ji guang mo shi xia zhi zao de bao bi jian de can yu ying li fen bu zhuang tai ,fa xian zai mai chong ji guang mo shi xia ,zhong jian wei zhi yan chen ji gao du fang xiang biao xian wei can yu la ying li ,bian yuan wei zhi biao xian wei can yu ya ying li ,er lian xu ji guang zhi zao de bao bi jian can yu ying li fen bu qing kuang jie ran xiang fan ;zai mai chong ji guang mo shi xia ,bao bi jian zhong jian wei zhi yan ji guang sao miao fang xiang de can yu ying li sui zhao wei zhi de bu tong biao xian wei la ying li he ya ying li jian de zhou ji xing bian hua ,er lian xu ji guang zhi zao de bao bi jian zhong jian wei zhi yan ji guang sao miao fang xiang biao xian wei can yu la ying li ,bian yuan wei zhi biao xian wei can yu ya ying li 。(3)yan jiu le li jiao liang he Zzhou chan ceng hang cheng (△Z)dui yu ji guang zhi jie zhi zao bao bi jian de zuo yong gui lv ,yi ji cheng xing fang shi dui yu ji guang zhi jie zhi zao xie po bao bi jie gou de zu zhi xing neng de ying xiang 。li jiao liang jue dui zhi de zeng jia jiang dao zhi chan ceng chen ji ceng de gao du jian xiao 。zai ji guang zhi jie zhi zao zhong ,dang △Zzai ge kuo fan wei nei shi ,ji guang zhi jie zhi zao guo cheng cun zai fu fan kui ji zhi ,ke yi da dao △Zyu chan ceng chen ji gao du xiang deng de zhuang tai ,shi xian wen ding de cheng xing 。ji yu ci fan kui ji zhi ,di chu 3Dfen ceng cheng xing fang shi (tong yi chen ji ceng bu tong wei zhi chu de AZbu tong )zhi zao biao mian gao du bu yi zhi de xie po bao bi jie gou de fang fa 。cai yong ping mian fen ceng he 3Dfen ceng cheng xing fang shi zhi zao de xie po bao bi jie gou de ping jun ying du bian hua bu da ,dan shi ying du fen bu ming xian bu tong ,qian zhe de la shen jiang du he shen chang lv lve da yu hou zhe 。sui zhao xie po bao bi jie gou qing xie jiao du de zeng jia ,ping jun la shen jiang du zeng jia ,shen chang lv jian xiao ,la shen jia zai fang xiang yu jing li hua yi biao mian de ga jiao ,ying xiang zhao yan hua yi biao mian de jian ying li ,dui yu la shen jiang du you zhao chong yao de ying xiang ,dang qing xie jiao du wei 20°shi ,zai ping mian fen ceng he 3Dfen ceng cheng xing fang shi xia ,la shen jia zai fang xiang yu shui ping fang xiang ga jiao fen bie wei 45°he 25°shi ,ji yu hua yi biao mian geng jia jie jin yu chui zhi zhuang tai ,yan hua yi biao mian de jian ying li jiao xiao ,rong chi bian jie ke yi cheng shou jiao da de la shen li ,ju biao xian chu jiao da de la shen jiang du ;dang la shen li de jia zai fang xiang yu shui ping fang xiang ga jiao wei 90°shi ,la shen jia zai fang xiang yu hua yi biao mian de ga jiao jiao xiao ,yan hua yi biao mian de jian ying li jiao da ,geng rong yi da dao qu fu ji xian ,biao xian wei jiao xiao de la shen jiang du 。(4)yan jiu le sao miao fang shi he Zzhou chan ceng hang cheng (△Z)dui yu ji guang zhi jie zhi zao xuan chui bao bi jie gou de ying xiang gui lv ,tan tao le ying xiang xuan chui bao bi jie gou ji xian jiao du de yin su 。xuan chui bao bi jie gou de cheng xing zhi liang shou dao sao miao fang shi (chan xiang sao miao he wang fu sao miao )he AZde ying xiang 。yu chan xiang sao miao fang shi xiang bi ,wang fu sao miao fang shi xia cheng xing chu de xuan chui bao bi jie gou biao mian ping zheng ju liang duan dui chen ,cheng xing zhi liang geng gao 。△Zdui xuan chui bao bi jie gou de jiao du jing du you zhao chong yao de ying xiang ,△Zde you hua shi de shi yan jiao du yu she ji jiao du de cha yi da fu jian xiao 。ran er ,xuan chui bao bi jie gou ke cheng xing de ji xian jiao du zhi neng da dao 32°zuo you ,△Zde you hua mo fa zeng jia xuan chui bao bi jie gou de ji xian jiao du 。ke cheng xing de xuan chui jie gou de ji xian jiao du shou dao rong chi biao mian zhang li 、fen mo liu chong ji li 、chong li zhi jian guan ji de zhi yao ,yu rong chi ji he xing zhuang he cai liao te xing you guan 。tong guo zheng jiao shi yan ,de chu le bu tong gong yi can shu (ji guang gong lv 、sao miao su du he song fen liang )tiao jian xia ,neng gou bao zheng xuan chui bao bi jie gou jiao gao jing du de Zzhou chan ceng hang cheng 。er ju ,Zzhou chan ceng hang cheng yu (P/Qm)1/4(Qm/V)cun zai zheng xiang guan de xian xing guan ji 。
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论文作者分别是来自大连理工大学的王鑫林，发表于刊物大连理工大学2019-04-22论文，是一篇关于激光直接制造论文,垂直薄壁结构论文,斜坡薄壁结构论文,悬垂薄壁结构论文,轴单层行程论文,大连理工大学2019-04-22论文的文章。本文可供学术参考使用，各位学者可以免费参考阅读下载，文章观点不代表本站观点，资料来自大连理工大学2019-04-22论文网站，若本站收录的文献无意侵犯了您的著作版权，请联系我们删除。
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