Brittle Cracking of Flanks of a Big Gear

Several teeth of a big helical gear were found cracked following coarse-grinding teeth after the gear was carburized. Visual observation shows that cracks are present only on the flanks at one side having an acute angle to the gear end. The cracks propagated from the flanks toward the gear end. SEM observation on the fracture surfaces reveals that intergranular and quasi-cleavage brittle fracture is the cracking mechanism of the flanks. The cracked flanks at the ??acute angle?? side have a weak ability to support the grinding stress induced by grinding tooth operation, which is mainly responsible for cracking of the flanks. The thick case-harden depth and weak inter-crystalline strength nature of the carburized layer facilitate the initiation and propagation of crack. Unsuitable grinding operations probably aggravate cracking of the flanks.     

小螺旋锥齿轮断裂失效分析

对小螺旋锥齿轮的断裂失效进行了分析，结果表明，齿轮在传动中出现偏载，造成了连续冲击过载，而使齿轮过早疲劳断裂，本文还讨论了造成偏载的可能性。     

齿轮开裂失效分析

采用断口分析、化学成分分析、低倍检验、金相检验和硬度测试等方法对某批经渗碳、淬火热处理及磨齿加工后放置一段时间发生开裂的齿轮的失效原因进行分析。结果表明：齿轮渗碳层碳化物级别过高,加上淬火后齿轮齿部应力集中,磨齿时又产生磨削裂纹,齿轮在放置期间由于应力导致裂纹扩展而开裂。     

Concept of Ultimate Fracture-Front Velocity in Cylindrical Cavity Expansion in a Brittle Material

Expansion of a cylindrical cavity in a brittle material is analyzed on the basis of the concept of the ultimate velocity of the fracture front. The boundary problems have been solved for the material regions of various states. The expansion pressure of a cylindrical cavity as a function of the expansion velocity in a ceramic material is given and compared to that of a spherical cavity.     

圆柱齿轮磨齿机的选型

对圆柱齿轮磨齿机中的蜗杆砂轮磨齿机和成型磨磨齿机的磨削原理及应用场合作了介绍,从用户的角度对机床选型、对机床供应商的要求作了分析,指出国内磨齿机机床厂家,应联合夹具专业厂商、磨料生产厂商组成强大的综合服务队伍,对于争夺日趋激烈的磨齿机市场具有现实意义.     

圆柱齿轮齿廓的测量不确定度评定

齿廓是校准标准圆柱齿轮的一个重要参数,本文依据JJG1008-2006《标准齿轮检定规程》检定规范,基于KLINGELNBERG P65齿轮测量中心,运用不确定度评定与表示方法,对标准齿轮齿廓的测量不确定度进行评定。     

轧机分配减速箱齿轮轴和齿轮的轮齿堆塌原因分析

轧机分配减速箱齿轮轴和齿轮在使用过程中发生轮齿堆塌而失效,通过化学成分分析、力学性能测试和金相检验等手段分析了堆塌产生的原因。结果表明:由于出现润滑故障,形成干摩擦,致使齿轮轮齿表面局部温升产生热塑流变现象,最终导致齿肉损伤,形成堆塌失效。提出防止此类失效的根本对策是防止出现供油系统故障。     

轴承齿圈开裂原因分析

使用了约4a（年）的轴承齿圈在服役过程中发生开裂。为查明其开裂的原因,通过化学成分分析、力学性能测试、宏观及微观检验对轴承齿圈进行了分析。结果表明：轴承齿圈开裂的原因是孔内壁表面腐蚀坑处产生微裂纹,加之齿圈本身强度低于技术要求值,在交变应力的作用下发生了疲劳断裂。     

Simulation of Coupled Processes of Deformation and Cracking in Elastic Brittle Materials

We propose an approximate model of combined deformation and microcracking of elastic brittle materials leading to the formation of a system of stochastically distributed shallow microcracks.     

CB30铸钢连接圈脆性开裂失效分析

对CB30铸造铁素体不锈钢连接圈内浇口产生裂纹的原因进行了分析。结果表明:该零件显微组织中存在马氏体脆性相是导致其脆性开裂的根本原因;通过改进连接圈内浇口结构以及浇铸后铸件的脱壳方式,并延长铸件的退火热处理保温时间,可以有效地避免环形类CB30铁素体不锈钢铸件的脆性开裂。     

圆柱齿轮冷锻成形技术探讨

探讨了几种圆柱齿轮冷锻成形技术,对圆柱齿轮冷锻特性进行了分析,并运用系统的观点对提高冷锻圆柱齿轮的轮齿精度做了探讨.     

大型调质输入轴开裂分析

某大型调质输入轴放置约9个月后开裂,采用宏观分析、化学成分分析、低倍检验、断口分析、金相检验以及力学性能测试等手段对输入轴开裂原因进行了分析。结果表明:该输入轴为在组织应力及氢析出所造成内应力共同作用下的氢致延迟开裂;输入轴原材料氢含量高、偏析严重、非金属夹杂物含量高以及锻造不充分,引起零件内部发生了氢气积聚,形成了较大的内应力,这是导致输入轴发生氢致延迟开裂的主要原因。     

波音飞机起落架轮轴镀铬修复工艺

波音飞机起落架在大修时，对零件有磨损、锈蚀、损伤的基体及防护层要求重新表面处理。波音飞机起落架主要结构件涉及的镀种为：镀硬铬及镀镉钛。本文介绍波音７４７飞机起落架轮轴镀铬修复工艺规范和要点，以及影响质量的因素。１电镀工艺轮轴材料４３４０Ｍ钢；它的抗拉...     

基于Fluent的圆柱齿轮流量计的密封性仿真分析

通过对圆柱齿轮流量计进行二维简化建模,用Fluent仿真软件的ICEM CFD模块进行网格划分,利用Fluent仿真软件对圆柱齿轮流量计进行了计算和密封性的仿真分析,得出了其速度矢量分布图,并且给出了各泄漏量的计算公式和每种泄漏所占泄漏总量的百分比,即为以后的整个流量计的设计提供理论依据。,提高流量计的寿命具有重要意义。同时还省去了大量的人工计算过程,极大地加快了计算速度。     

Strength of Cylindrical Specimens Subjected to Laser Hardening along the Generator and a Spiral Path

We have shown that the path of a continuous CO₂-laser beam over the cylindrical surface of specimens in the course of their hardening substantially affects the strength of steels in cyclic axial tension and bending with torsion. Hardening on a spiral path ensures higher mechanical parameters as compared with that along the generator of the cylindrical surface.     

Stability of Cylindrical Shells with Regard for Dispersed Cracking in the Material

The problems of bifurcation stability of cylindrical shells are stated and solved with regard for the damage to a material in the subcritical stressed state. The appearance of defects in the material is explained by the inhomogeneity of its microstrength. The defects are simulated by a system of plane elliptic and circular cracks statistically uniformly and isotropically distributed over the volume of a shell. The mathematical statement of the problem is performed within the framework of the Kirchhoff–Love hypotheses by using the concept of continued loading. The solution of the problem is constructed for the case of uniform compression of the shell.     

汽车齿轮的振动测试与分析

阐述汽车齿轮振动测试系统的组成和测试方法,并利用测试结果对四种典型故障引起的振动进行分析。研究引起汽车齿轮振动的主要原因,为降低汽车齿轮的振动和噪声提供了某些依据。     

Metallurgical Analysis to Evaluate Cracking in a 316L Grade Stainless Steel Spiral Heat Exchanger

A spiral heat exchanger (SHE) constructed of Grade 316L stainless steel developed a leak after 8 years of service as a condenser on a distillation tower. Examination of the SHE identified the leak as being located on the cooling water side in the heat affected zone (HAZ) of a weld joining two plates. Cooling water deposits were observed in a V-shaped corner formed by the weld. A metallurgical examination identified the presence of transgranular cracks at the HAZ on the cooling water side. Analysis of the cooling water revealed the presence of chlorides. Based on the metallurgical analysis and the presence of chlorides, it was determined that the cracks and resulting leak were the result of chloride stress corrosion cracking.     

圆柱齿轮流量计变压修正方法研究

为研究液压油介质的圆柱齿轮流量计在变压工况下仪表系数修正方法,利用变压体积管流量标准装置对齿轮流量计在多个压力点下进行了校准试验,通过解耦曲线拟合和二元曲面拟合两种方法对校准结果进行了拟合计算。经两种方法拟合计算,各工况下齿轮流量计仪表系数与校准结果误差均小于0. 4%,证明两种拟合修正方法的有效性。