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一台QY25B型汽车起重机与一台QY16E型汽车起重机共同吊装一台约40t的变压器时,QY25B型汽车起重机回转支承装置的连接螺栓全部断裂,但检测螺栓强度却完全符合设计要求。现场勘察,发现QY25B型汽车起重机的负荷已大大超出其吊重范围,据此计算连接螺栓的受力已超出设计要求。检验校核证明,产品设计中螺栓的布置有些不当。回转支承装置连接螺栓有两组,它们分别将内圈和外圈与转台和车架支承座牢固地连接起来,连接螺栓在起重机工作时受到由O～P(载荷)的循环载荷作用,所以在安装这些螺栓时须使其预紧力很大;同时,螺栓在工作中还受到动载荷的作用,因此必须考虑其疲劳破坏的可能性。回转支承装置内外螺栓的规格和数目相同,且均匀分布,内圈螺栓受力较
When a QY25B truck crane and a QY16E truck crane are hoisting a transformer of about 40t together, the connecting bolts of the slewing bearing of the QY25B truck crane all break, but the test bolt strength fully meets the design requirements. Site investigation and found QY25B truck crane load has greatly exceeded its lifting range, thus calculating the stress of the connecting bolts has exceeded the design requirements. Proof of inspection proved that the product design bolt some inappropriate layout. There are two sets of slewing bearing connecting bolts, which respectively connect the inner ring and the outer ring with the turntable and the frame supporting seat. The connecting bolts are subjected to the cyclic loading of O ~ P (load) when the crane is working, These bolts should be installed to make the preload is very big; the same time, the bolt in the work also by the dynamic load, it must consider the possibility of fatigue damage. Rotary support device inside and outside the bolt the same number and size, and evenly distributed, the inner force of the bolt more than