共查询到19条相似文献,搜索用时 125 毫秒
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《理化检验(物理分册)》2017,(11)
某天然气管道用直通球阀卡套螺母在服役期间发生开裂。采用宏观观察、断口分析、腐蚀产物分析、化学成分分析、显微组织分析等方法对该卡套螺母的开裂原因进行了分析,并进行了热模拟试验及晶间腐蚀试验。结果表明:化学成分不合格和固溶处理不充分是卡套螺母开裂的主要原因;大量非金属夹杂物的存在导致电化学腐蚀,是卡套螺母开裂的次要原因。 相似文献
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通过理化检验、仿真分析和装配拧紧试验等方法,对HB4-49收紧螺母的开裂性质和原因进行了分析。结果表明:该螺母开裂的原因为拧紧力矩过大。 相似文献
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王文斌 《理化检验(物理分册)》2013,(7):482-485
通过化学成分分析、硬度测试、宏观及微观检验对某螺母螺纹根部出现开裂的原因进行了分析。结果表明:螺母开裂的原因是其存在设计缺陷,即退刀槽设计为模锻件的分模面,致使关键部位螺纹根部存在非锻造组织而使强度弱化。 相似文献
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王湘苏 《理化检验(物理分册)》2012,(8):557-558,564
调整螺母在调质处理后探伤时发现有裂纹,采用宏观检验、化学成分分析、金相检验等方法对其开裂原因进行了分析。结果表明:该批调整螺母开裂是由于明显的带状偏析和较多的夹杂物引起的淬火裂纹,同时由于回火温度过高,使得裂纹两侧脱碳出现网状铁素体。 相似文献
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周艳 《理化检验(物理分册)》2001,37(6):266-267
对开裂杯形螺母的力学性能和化学成分进行了检验分析,并进行了工艺试验。结果表明,毛坯尺寸偏短是造成开裂的主要原因。提出了改进措施。 相似文献
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某批GH2036螺母在使用过程中,有8件的表面出现了开裂现象。通过宏观观察、金相检验、硬度测试、断口分析等方法,确定了螺母开裂的原因。结果表明:该批零件局部区域存在大量呈带状分布的球型夹杂物,球型夹杂物的类型为含锰、硅和氧的硅酸盐型夹杂物,由于夹杂物的存在,破坏了材料的连续性,降低了材料的强度,同时由于夹杂物与基体之间变形速率的差异,导致了裂纹在棒材成型过程中的扩展,最后在外力的作用下发生了开裂。 相似文献
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徐振振 《中国新技术新产品》2019,(8)
在产品设计中需要转动、移动,螺旋传动是实现此种方式的有效模式。螺旋传动主要就是通过螺杆以及螺母构成,论述螺杆螺母传动机构的设计模式与手段,可以提升二者的配精密度,降低运行过程中产生的噪声问题。基于此,该文主要分析了螺杆螺母传动机构的作用,了解了螺杆与螺母传动类型,探究了螺杆螺母传动机构的设计方式与手段,仅供参考。 相似文献
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锚杆轴力测量对评价围岩稳定性具有重要意义。采用接触力学理论建立了锚杆构件振动频率与锚杆轴力关系模型,开展了锚杆锚固系统振动试验。通过采集螺母和托盘的振动响应信号,对不同受力条件下螺母和托盘的非线性振动特性进行了分析,获得了螺母和托盘振动频率与轴力关系;提出了基于螺母和托盘非线性振动特性的实时轴力无损检测方法。试验结果表明:随着锚杆轴力增加,螺母和托盘振动频率呈非线性增加,螺母频率大于托盘,托盘频率的增长率大于螺母;且二者振动频率增长趋势与轴力大小均为单值映射关系,通过测量螺母和托盘的振动频率可以实现锚杆轴力的无损检测。 相似文献
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在17-4PH不锈钢高锁螺母的加工过程中,发现其螺纹部位有裂纹产生。采用微观观察、加工工艺分析、挤压过程分析等方法研究了该螺母裂纹产生的原因。结果表明:裂纹是在挤压过程中产生的,挤压前坯料硬度偏高、挤压变形量偏大,使材料的塑性及心部流动性变差,最终导致螺母心部产生裂纹。对挤压前的坯料进行双重退火处理,可以避免螺母在加工过程中产生裂纹。 相似文献
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采用纵波法并使用自制的内螺纹夹具,分别选择普通螺母和自锁螺母来标定螺栓,通过不同的拧紧策略和标定方法,分析普通螺母和自锁螺母标定螺栓特征曲线的差异.结果表明:采用普通螺母和自锁螺母标定螺栓因方法不同会获得不同的标定特征曲线,自锁螺母的锁紧扭矩使螺栓温度升高导致超声波声时差增加,因此获得的标定特征曲线会平行右移. 相似文献
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A forensic investigation was performed on an ATV that was involved in an accident in which the vehicle struck a tree. Postaccident, the front knuckle/tie rod end connection was found to be loose. The prevailing torque nut was found positioned at the end of the tie rod end bolt such that there was a gap between the face of the nut and the knuckle. The subject nut exhibits machining asperities that resulted from close contact with the knuckle face. EDS analysis of the corrosion product ring on the knuckle face revealed the corrosion product was zinc oxide, which had formed due to galvanic corrosion between the galvanized nut and the carbon steel knuckle. Scuffing patterns on the nut, wear patterns on the bolt, and lack of damage to the knuckle corrosion ring confirmed that the nut could not have loosened from the as-manufactured position to the postaccident position. No viable nut loosening mechanism was identified other than deliberate, manual manipulation. 相似文献
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G. H. MAJZOOBI G. H. FARRAHI S. J. HARDY M. K. PIPELZADEH N. HABIBI 《Fatigue & Fracture of Engineering Materials & Structures》2005,28(6):557-564
The effect of nut geometry, curved spring washer and a sealing material (Teflon tape) on the fatigue life of M12 and M16 ISO bolts was investigated. This was accompanied by the study of the axial and bending stress distribution in threads by numerical simulation of bolt and nut connections using the finite‐element method. The experimental results showed that the highest fatigue life is achieved for a slotted tapered nut. The presence of a spring washer also increases the fatigue life, providing that the correct tightening torque is applied to produce a pretension in the bolt. The use of Teflon tape as a filling material between engaging threads of the bolt and nut is shown to significantly increase the fatigue life. On the whole, the highest fatigue life is obtained for a slotted tapered nut using washer. Four fracture mechanisms were observed for bolt–nut connections during the fatigue tests. 相似文献
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P. Senthil Kumar N. Arun Kumar R. Sivakumar C. Kaushik 《Journal of Materials Science》2009,44(21):5894-5899
The main commercial product of the cashew tree is the cashew apple and nut. Cashew nut is regarded as lost crop in the content
of agricultural produce of India despite its industrial and export potentials. After separation of nut from the cashew fruit,
the nut shell is disposed into the environment and this is acting as a waste. The nut shell containing a dark reddish brown
viscous liquid is called cashew nut shell liquid (CNSL) and consists of 70% anacardic acid (polyphenol), 18% cardol, and 5%
cardanol. This waste material is having twofold advantages: CNSL is a low-cost phenol, which is having many industrial applications
and after extraction of CNSL from the shell, the shell is acting as a fuel for many boilers. Cashew nut shell liquid was extracted
from cashew nut shell by indirect leaching process using soxhlet extraction equipment. Different solvents were used in the
extraction of CNSL from the cashew nut shell (CNS) and a comparison was made between them. Among all the solvents acetone
gives more amounts of CNSL and its properties rely with the industrial CNSL. The operating conditions for the extraction were
60 °C and 1 atm; in every 25 g of cashew nut shell used for the extraction, 8.75 g CNSL was obtained. The CNSL was further
separated into cardol, cardanol, and anacardic acid (polyphenol) using an extractant, ammonium hydroxide, with the aid of
mechanical shaker equipment. Subsequently, the polyphenol was further separated into dihydric phenols (resorcinol) and monohydric
phenol (phenol). 相似文献
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Threaded fasteners are widely used for temporary joining of different components that require occasional disassembling. However, threaded fasteners may have the problem of loosening under vibrating conditions, which may lead to decreasing clamping force and, thereby, a system failure. In the present experimental investigation, anti-loosening ability of various fastening elements, such as conventional nut, nylock nut, flat washer, spring washer, inside and outside serrated washer, is tested with a conventional M16 high-tension steel bolt. A hybrid double nut is used to clamp the plates in which a conventional nut is used to tighten first, and one nylock nut is then placed at the outer side for further tightening. An adhesive-bonded nut is also tested, where an adhesive is placed between bolt and nut threads. All these fasteners are tested in terms of their loosening characteristics. Accelerated vibrating conditions are used for the test on an indigenously made test rig. A split bolt with taper pin is introduced for the first time to reduce loosening of fasteners. The split bolt with taper pin shows considerably good anti-loosening property compared with other threaded fasteners tested in this work. 相似文献
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目的 针对航天器结构用不同材质的侧面销钉和螺母组件在实际的使用工况下极易出现腐蚀与咬死的问题,对不同材质的侧面销钉和螺母组件的耐蚀性能进行研究。方法 分别在高量级腐蚀条件和低量级腐蚀条件下,采用重复拧紧试验方法,对侧面销钉和螺母开展耐腐蚀性能、防咬死性能研究。结果 在高量级腐蚀条件下,无表面处理的30CrMnSiA侧面销钉+TC4螺母组件在经历12 h腐蚀试验后,其表面发生了100%的腐蚀;经历过重复拧紧试验的30CrMnSiA(表面镀镍)侧面销钉+TC4螺母组件,在经历12h腐蚀试验后,其表面腐蚀面积>50%;未经历重复拧紧试验的30CrMnSiA(表面镀镍)侧面销钉+TC4螺母组件,在经历12 h腐蚀试验后,其腐蚀面积约为25%~50%。在低量级腐蚀条件下,经历重复拧紧试验和未经历重复拧紧试验的30CrMnSiA(表面镀镍)侧面销钉+TC4螺母组件均未发生表面腐蚀,而30CrMnSiA(无镀镍)侧面销钉+TC4螺母组件的腐蚀面积为25%~50%。镀镍处理可以显著提高30CrMnSiA侧面销钉的耐腐蚀性能。结论 经过镀镍表面处理的30CrMnSiA侧面销钉比经过表面钝化处理的1... 相似文献
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居民住宅内与水表连接的黄铜螺母发生断裂,造成管路泄漏.采用宏、微观检验方法对失效螺母进行了分析.结果表明,黄铜材料中含有较多的铅,使金属基体脆化并在晶界上存在脆性共晶体网膜,加上金属中还存在孔洞、缩松等铸造缺陷,是造成螺母断裂的主要原因. 相似文献