After the Spring Festival, the new year is the climax of the installation of wind turbines. For nearly three years of wind turbines off network and network problems such as high and low wear continue to occur, the recent research efforts of relevant experts have completed the technological transformation of low voltage ride through capability, basically solves the problem. And mechanical equipment within the cabin, such as mechanical loosening caused by the hub of the head, the wind wheel fall head caused damage to the common, large and small wind wheel fall in the past few years, there are hundreds of units. Even from 2009 to 2011, nearly three years, the collapse of more than ten million yuan, per units, tens of billions of dollars of losses. The national wind energy industry is a very small number, the loss is not worth mentioning, ought to pay tuition. And to the wind turbine enterprise, it is not a small number of losses, and even lead to the closure of enterprises. So far, the real reason for the collapse of the whole machine has not been found, the wind wheel fall head more no one to study and analysis. (from the foreign information view, the wind machine collapse has never been) the collapse of the domestic machine dozens of what? From the collapse site, most of the fracture flange in the tower and the tower at the junction of the wind turbine and impeller broken fall head injury (including the cabin equipment damage) is associated with the installation technology, also has a significant relationship between the quality and strength of bolts, studs and nuts.
Wind power business executives should pay attention to the. First of all, it must be clear that the wind turbine is a static state, or dynamic state. This is related to the technical problems of the installation of fasteners (foreign technical data is not sold to the domestic). The domestic fastener standard has the Ministry of chemical industry standard, has the aviation standard, has the Ministry of construction standard and so on, each has the scientific principle. Modern people say that the use of static or dynamic connection fastening is different. This is related to the installation of high strength bolt and nut preload and preload torque value of the important data, related to the installation of the wind turbine after the collapse of the machine and the quality of decades will not collapse. Many wind power executives also believe that the wind turbine belongs to the static work category, only the wind turbine blade number dynamics, it will cause the wind turbine collapse of dozens of major accidents, the future will continue to fall. Wind power equipment engineers did not know the tower and the tower tube connection is dynamic or static, listen to the irresponsible experts say is static on the static requirements to tighten the connection of the bolt and nut. This is the result of bolt nut loose, the tower and the tower, the tower suddenly broken friction fastening bolt is connected with the hub flange hole wall friction, caused by falling head wind wheel hub. Even the cabin equipment damage, the light broke maple leaf. Even the wind wheel fall head caused by strong vibration of the tower on a pit. Besides the tower and the tower joints due to the high strength bolt and nut not according to the Ministry of construction standards issued by the Peoples Republic of China construction industry, construction machinery and equipment specification of high strength fasteners, JG/T5057.40-1995 preload and pre tightening torque values (friction coefficient = 0.14)". What is construction and mechanical equipment? Bridges, large machinery installation, wind power equipment, construction and installation in the use of high strength bolt and nut of the tower crane, dock crane bearing stud and ship heavy crane. The import of large equipment installation must by the Ministry of Construction issued the standard implementation of JG/T5057.40-1995 fastening connection, preload and torque value (the friction coefficient is larger than 0.14) technical requirements, or by Germany to wind turbine fastening technology requirements (DASt standard). Large diameter high strength bolt preload and pre tightening torque to ensure that the minimum value of the bolt and nut can not be loosened for 50 years. This is the scientific basis for the scientists to study, the worlds general dynamic working state of the connection fastening scientific methods to prevent the bolt and nut loosening of the scientific and technological methods. From a mechanical point of view, when the scientific torque fastening, high strength bolts by their own flexibility to tighten the bolt and nut will not loose, only by science. Standard requirements of preload and pre tightening torque (minimum friction coefficient is larger than 0.14) "technical requirements for fastening the tower and the tower flange connection of high strength bolt nut loose. The tower cylinder is connected with the strong vibration and shock vibration caused by the rotation of the wind wheel and the rotation of the wind blade. The screw part can not be friction with the hole wall of the flange plate of the tower barrel, so that the bolt can not be broken by friction. On the contrary, the low friction coefficient of GB/T1228 is only 0.11 in the steel structure. So it will cause the bolt and nut is not loose, the bolt is broken. Sudden, unable to prevent.
Due to competition, enterprises of low friction fastening system numerical requirements, the collapse of a bridge crane collapse, mechanical equipment damage It is often seen. The release of "technical conditions of fasteners Peoples Republic of China construction machinery and equipment of high strength standard in 1995 the Ministry of Construction: JG/T5057.40 preload and pre tightening torque values (friction coefficient = 0.14)". This standard is the senior scientists from the new version came out, warning that connection fastening requires dynamic requirements, static requirements. Strictly speaking, high strength bolts, nuts, the quality of unqualified points. The high strength bolt used in the dynamic state is that the core part of the bolt must meet the requirements of the mechanical performance. In the pre tightening force and pre tightening torque values (friction coefficient = 0.14) fastening values are not broken, will not yield more elongated, not slippery silk. Otherwise it is the quality of the bolt, it is not a super twist problem. Because the wind turbine on the use of 10.9 - grade high - strength bolts must be reached 90% martensite, tempered out of the Suo s body, rather than ferrite. So the torque value (friction coefficient 0