大跨度桥式起重机平衡台车开裂机理研究

发布时间：2018-02-26 13:24

本文关键词： 桥式起重机裂纹平衡台车 CAE仿真　出处：《武汉科技大学》2011年硕士论文　论文类型：学位论文

【摘要】：近20年以来,我国起重机行业发展迅猛。由于起重机在设计、制造、使用、维护等各环节中出现的各种问题,同时也由于起重机本身属于间歇性动作机械,具有短暂、重复和周期性工作的特点,起重机的钢结构会产生反复的弯曲、剪切应力,启动和制动时还要承受额外的冲击载荷,因此而产生的起重机钢结构裂纹甚至断裂会导致发生各种人身伤亡事故。在我国现有的起重机械中,特别是使用年限较长或工作特别频繁的起重机,裂纹等缺陷时有发生,其裂纹长度从几毫米到几百毫米不等。由于起重机金属结构件一般体积较大、造价较高等客观因素,因此不可能发现缺陷就立即进行更换。虽然发现产生裂纹,但是很多桥式起重机仍然在生产第一线服役,这样的设备无疑是人们头顶的一枚炸弹。裂纹的发生具有时间不确定性,若发生钢梁突然脆性断裂,其后果不堪设想,这也给安全生产带来了很大的隐患。所以对起重机金属结构裂纹扩展的检测、分析以及控制的研究,对于保障安全生产有着重要的意义。某钢铁企业冷轧厂生产用的多台大跨度桥式起重机,额定起重量为45/15t,跨度为37.5m。投入使用仅仅1年,发现四台吊车的大车运行平衡台车钢结构出现若干裂纹,严重威胁到起重机的正常运行和企业的正常生产。通过对该起重机平衡台车进行现场实测,应用无损探伤技术,掌握了该平衡台车的裂纹分布情况,对该起重机实际运行状态下典型部位的应力历程进行了测试,掌握了该起重机现场运行过程中的第一手资料。采用有限元前处理软件HyperMesh建立了该起重机桥架结构及平衡台车的整体有限元分析模型。通过分析该起重机的运行特点,运用CAE仿真技术对该起重机桥架特别是平衡台车在典型工况下应力分布规律进行了研究。在CAE仿真过程中,应用Solidworks软件,根据起重机桥架与平衡台车钢结构几何特征,采用合适的单元类型,建立了桥式起重机桥架以及平衡台车的三维CAE仿真模型,并应用OptiStruct对多种典型载荷工况进行了有限元仿真计算,结合测试结果,表明啃轨侧向力是影响平衡台车强度的主要因素。通过CAE仿真分析,模拟出了该起重机运行过程中的啃轨力的大小。现场实测及CAE仿真分析结果表明,在侧向啃轨力的作用下,平衡台车腹板与轴承座焊接处的应力水平较高,超过材料的疲劳许用应力,且由于啃轨力随机变化,在一个工作循环内该处的应力变幅循环数远远高于工作循环数,使得该处很快达到疲劳寿命,出现裂纹,这便是该起重机运行仅1年平衡台车即出现大量裂纹的主要原因。针对该大跨度桥式起重机平衡台车疲劳强度低的现状,本课题提出了该平衡台车的改进方案,并对改进方案在危险载荷工况作用下的应力场进行了CAE仿真分析,表明按照该方案改进平衡台车后,原始结构开裂部位的应力水平下降了50%,已低于材料的疲劳极限,该方案已实施运行3年,运行效果良好。
[Abstract]:Over the past 20 years, China's rapid development of the industry. Because the crane crane in the design, manufacture, use, maintenance and other problems in various aspects, but also because the crane itself belongs to the mechanical action of intermittent, with short, repeated and periodic work, steel structure heavy machine will produce repeated bending the shear stress, but also bear the impact load additional starting and braking, the resulting crane crack in steel structure and fracture will lead to various casualty accidents.
In our country the existing hoisting machinery, especially the longer life or work especially frequent crane, cracks and other defects occur, the crack length from a few millimeters to several hundred millimeters. The crane metal structure general large volume, high cost and other objective factors, it is not possible to find defects immediately replacement. Although found cracks, but many cranes still in the production of the first line service, this equipment is undoubtedly one of the head of a bomb. The occurrence of cracks with time uncertainty, if there is a sudden brittle fracture of steel beam, the consequences be unbearable to contemplate, it also brings great danger to the safety in production. So the detection of extended the crane metal structure crack, analysis and control, has important significance for guaranteeing safe production.
The cold rolling mill with an iron and steel enterprise multi big span bridge crane rated lifting weight is 45/15t, the span is 37.5m. put into use in just 1 years, found four crane crane operation balance trolley steel structure have some cracks, a serious threat to the normal production and operation enterprises crane. Through the field test of the crane balance trolley, nondestructive testing technology, mastered the balance trolley of the crane crack distribution, the actual operation condition of the typical parts of the stress process were tested, mastered the crane field during the operation of the first hand information.
A finite element analysis model of the crane structure and balanced car by using the finite element pre-processing software HyperMesh. Through the analysis of the operating characteristics of the crane, using CAE simulation technology of the crane bridge especially balance bogie in the typical working conditions of stress distribution are studied. The CAE simulation process, the application of Solidworks software according to the crane, trolley and balance geometry steel structure characteristics, using the appropriate unit types, established a three-dimensional simulation model of CAE bridge crane trolley and balance, and the application of OptiStruct of various typical loading conditions were analyzed by finite element simulation, combined with the test results, show that the rail gnawing lateral force is the main factor affecting the strength of the car balance through CAE simulation, simulation of the size of the crane rail gnawing force during operation. The actual measurement and CAE simulation Analysis results show that the lateral track biting force, balance trolley and the bearing seat of the welding point with high stress level, more than the material allowable stress and fatigue, due to random variation of the force of rail gnawing, in a working cycle of the stress amplitude is much higher than the cycle number of cycles, the they soon reached the fatigue life of crack, this is the main reason for the crane running only 1 years is the emergence of a large number of car balance crack.
In view of the large span bridge crane trolley balance of low fatigue strength, this paper puts forward the improved scheme of the balance of the trolley, and the improved scheme is in danger of loading the stress field was simulated in CAE, that in accordance with the scheme to improve the balance after the car, the original structure cracking stress level decreased 50%, has been lower than the fatigue limit of material, the program has been running for 3 years, the operation effect is good.

【学位授予单位】：武汉科技大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH215

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