本文選題：高強(qiáng)度螺栓 + 斷裂　； 參考：《湖南大學(xué)》2012年碩士論文

【摘要】：由于螺栓斷裂問題在工程應(yīng)用中普遍存在,對(duì)社會(huì)生產(chǎn)和財(cái)產(chǎn)、人身安全危害巨大。本文針對(duì)HXD1C機(jī)車轉(zhuǎn)向架驅(qū)動(dòng)單元抱軸箱與電機(jī)連接的10.9級(jí)高強(qiáng)度螺栓在裝配后機(jī)車出廠前發(fā)生批量斷裂問題,以螺栓為研究對(duì)象,通過對(duì)螺栓的受力、裝配尺寸、裝配工藝分析,并采用理化檢測方法對(duì)斷裂螺栓進(jìn)行進(jìn)一步分析,發(fā)現(xiàn)了螺栓斷裂的原因。采取改進(jìn)螺栓設(shè)計(jì)和螺栓工藝等措施,保證螺栓的正常工作和機(jī)車的正常安全運(yùn)行。本文的主要研究結(jié)果如下： (1)通過對(duì)抱軸箱和電機(jī)的接口尺寸和抱軸箱、電機(jī)裝配過程的分析,排除了因?yàn)榱悴考缓侠淼脑O(shè)計(jì)和裝配工藝而導(dǎo)致螺栓的異常受力而遭到破壞這一原因。同時(shí)也通過螺栓的扭矩試驗(yàn)、破壞扭矩實(shí)驗(yàn)、液壓扳手的校核,證明了在螺栓裝配過程中的裝配操作符合操作規(guī)范要求。 (2)對(duì)螺栓采用斷口分析方法,發(fā)現(xiàn)螺栓斷口呈現(xiàn)脆性斷裂特征,并根據(jù)螺栓斷裂一般發(fā)生在安裝后一段時(shí)間這一延遲斷裂的特點(diǎn),初步確定了螺栓屬于氫脆斷裂。 (3)采用化學(xué)成分分析、力學(xué)性能試驗(yàn)等測試表明：螺栓的原材料以及該批螺栓的材質(zhì)和熱處理狀態(tài)尚好；通過金相檢測發(fā)現(xiàn)裂紋由細(xì)小腐蝕坑坑底萌生,腐蝕坑坑底的灰色物可能為發(fā)黑時(shí)產(chǎn)生的氧化層。從而推斷細(xì)小腐蝕坑在發(fā)黑之前已產(chǎn)生。因此,螺栓在制造過程中曾發(fā)生過度酸洗,使螺栓的螺桿與其六角頭連接處(R角過渡處)表面產(chǎn)生細(xì)小腐蝕坑,從而引起螺栓表面吸氫；同時(shí),螺栓安裝后在其螺桿與其六角頭連接處(R角過渡處)存在較大應(yīng)力集中,促使螺栓發(fā)生氫致延遲斷裂。 (4)通過對(duì)螺栓斷裂前后不同工藝的比較,找到了最終使螺栓產(chǎn)生氫致延遲斷裂的工藝原因。因?yàn)槁菟ǖ挠昧现睆綔p小以減少磨削加工次數(shù),從而導(dǎo)致了螺栓的過渡圓角半徑過小,在此圓角處產(chǎn)生應(yīng)力集中。最后對(duì)生產(chǎn)工藝進(jìn)行了改進(jìn),新工藝主要是：增大了過渡圓角半徑,并增加了去氫處理工藝。采用新工藝生產(chǎn)的螺栓安裝在機(jī)車上后未出現(xiàn)類似斷裂情況,保障了機(jī)車的正常運(yùn)行。從而徹底解決了螺栓的斷裂問題。
[Abstract]:Because the bolt fracture problem is common in the engineering application, it has great harm to the social production and property and the personal safety. In this paper, the 10.9 grade high strength bolt which is connected with the motor in the driving unit of the HXD1C locomotive bogie drive unit has the problem of mass fracture before the locomotive is out of the factory. The bolt is the research object and the force of the bolt is taken as the research object. In order to ensure the normal work of the bolt and the normal operation of the locomotive, the main results of this paper are as follows: the main research results are as follows:
(1) through the analysis of the interface size of the axle box and the motor and the assembly process of the spindle box and the motor, the cause of the abnormal stress caused by the bolt is eliminated because of the unreasonable design and assembly process of the parts. At the same time, the bolt torque test, the failure torque experiment and the checking of the hydraulic wrench have proved that the bolt is in the bolt. The assembly process in the assembly process meets the requirements of operation specification.
(2) the fracture analysis method of bolt is used to find the characteristics of the brittle fracture of the bolt fracture, and the bolt fracture is usually characterized by the delayed fracture for a period of time after installation, and it is preliminarily determined that the bolt is a hydrogen embrittlement fracture.
(3) the results of chemical composition analysis and mechanical properties test show that the raw material of bolt and the heat treatment state of the bolt are good, and the cracks are germinating from the bottom of the small corrosion pit through the metallographic examination, and the gray matter at the bottom of the corrosion pit may be produced by the oxidation layer produced when the black pit is blackened. It has been produced before. Therefore, the bolt has been excessively pickled during the manufacturing process, making the bolt screw and its six corner joint (the R corner transition) produce a small corrosion pit, thus causing the bolt surface hydrogen absorption; at the same time, the bolt is installed at the connection of its screw and its six corner head (the transition of the corner of the corner of the R) after the bolt is installed, to promote the bolt. Hydrogen induced delayed fracture occurred.
(4) through the comparison of the different processes before and after the bolt fracture, the technological cause of the delayed fracture of hydrogen induced by the bolt was found, because the diameter of the bolt was reduced to reduce the grinding processing times, and the transition radius of the bolt was too small and the stress concentration was produced at the corner. Finally, the production process was improved. The new technology is mainly: increasing the radius of the transition angle and increasing the dehydrogenation process. The bolt is installed on the locomotive without a similar fracture condition, which ensures the normal operation of the locomotive. Thus the bolt fracture problem is completely solved.
【學(xué)位授予單位】：湖南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2012
【分類號(hào)】：U260.331.7;TH131.3

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