渗碳淬火工艺对齿轨轮残余应力和变形影响的仿真研究

根据热动力学原理及应力应变理论,采用有限元方法建立齿轨轮热处理模型,通过DEFORM软件模拟了渗碳淬火工艺对齿轨轮组织和应力的影响,得出齿轨轮渗碳淬火中马氏体的体积分数和应力场的变化,并研究了不同的淬火温度对齿轨轮硬度、残余应力及变形的影响规律。     

基于OpenGL的直齿锥齿轮三维参数化建模与传动仿真

通过对直齿锥齿轮的三维建模设计部分研究,开发了一种基于OpenGL图形内核的,集几何设计﹑动态仿真和力学计算于一体的弧齿锥齿轮专用建模软件。通过便捷的参数输入,实现了直齿锥齿轮的三维实体模型的自动造型,大大提高设计速度。且在建模过程中直接利用方程建立球面渐开线,从而保证了齿形的准确性,为后续直齿锥齿轮的有限元力学计算提供了精确的模型。     

矿用减速器太阳轮齿面PVD表面改性的研究

针对矿用减速器太阳轮接触强度最小安全系数通常小于1.25,即可靠度不理想的问题,对太阳轮常用材料17CrNiMo6进行物理气相沉积(PVD)处理。将其表面附着TiN涂层、TiC复合层,并对这2种涂层进行厚度、硬度、密着力、EDS分析。研究表明:齿面进行PVD表面改性虽然具有粗糙度良好、涂层均匀以及密着力好等优点,但其硬度有所降低。     

斗轮机回转齿轮断齿原因分析

发电厂煤场斗轮机回转齿轮发生断齿,根据成分分析、金相检验、硬度测试以及断口形貌分析的结果,认为由于齿轮表面硬化层中淬火裂纹存在,在运行中受较大冲击后发生了冲击断裂,并对防止淬火裂纹提出了建议。     

球磨机对开大齿轮新型铣齿加工方法

提供球磨机对开大齿轮一种新型的冷热加工工艺方法.解决以往大齿轮加工中出现的材质硬度不均、工艺留量、热处理应力释放变形、齿形曲线拐点、齿面啮合、齿轮齿底清根、刀具选用等问题,通过优化工艺设计方法,实现了大齿轮加工的高标准、高质量.     

水射流喷丸强化的试验研究

为获得水射流喷丸强化对材料表面力学特性和疲劳寿命的影响规律,选择喷丸压力、移动速度和靶距为影响因素,应用水射流对2A11铝合金和45钢进行喷丸试验;采用显微硬度计和X射线应力分析仪分别测定喷丸表面显微硬度和表面残余应力,利用扫描电子显微镜进行疲劳断口形貌观察,应用能谱仪进行内部疲劳源区夹杂物成分分析,获得水射流喷丸强化增益效果及疲劳裂纹萌生机制,指出水射流喷丸可以提高两种材料的表面显微硬度、表面残余压应力和疲劳寿命,并存在最大表面显微硬度靶距和最大表面残余压应力靶距,在试验条件下,2A11铝合金和45钢喷丸疲劳试样比未喷丸疲劳试样的疲劳寿命分别最大提高1.74倍和2.67倍,且水射流喷丸疲劳裂纹萌生位置的机制与传统喷丸相同。     

基于B样条曲面精确建模的斜齿轮接触分析

斜齿轮齿廓曲面是一种复杂的螺旋曲面,为满足齿面接触强度分析的精度要求,基于B样条曲面造型原理在ANSYS中建立了精确齿面的斜齿轮实体模型,并对某矿用减速器斜齿轮有限元模型进行了静接触分析,得到了斜齿轮副接触状态和应力大小的一般规律,同时验证了基于B样条方法建立的齿廓曲面的可靠性和精确性。     

矿井提升机减速器齿轮开裂分析

某矿主井提升绞车减速器二级齿轮在安装使用不到2年时发生齿轮齿而开裂,而该设备按设计要求应止常运行15年以上。矿井提升绞车不仅担负着矿井煤炭提升运输的主要任务,而且还承担人员的运输工作,一旦减速器齿轮开裂造成齿轮断裂导致提升机失控,对矿井生产和安全将造成严重影响。因此有必要对开裂的齿轮进行综合分析,查找造成齿轮开裂的原凶,以避免事故的发生,     

Relation between Sound Emission Occurring during Quenching and Mechanical Properties of the Steel after Quenching

Quenching and tempering often represent the final stage in the production of machine components of the manufacturing process. Final mechanical properties, such as residual stress and hardness profiles, depend on optimum parameters of a quenching process and monitoring of the process itself. The paper treats an experimental setup comprising detection of sound emission in the course of a quenching process. Due to heat transfer from a specimen's surface to a quenching medium, film boiling and nucleate boiling occur round a heated specimen, which strongly affects quenching. An investigation of sound emission in the quenching process was carried out with cylindrical specimens made of chrome-molybdenum heat treatable steel 42CrMo quenched in different quenching media. Sound-pressure signals demonstrated by different amplitudes depending on time at different frequencies are shown in 3-D diagrams. It has turned out that an analysis of sound-emission signals can provide useful information that confirms differences occurring in quenching with different quenching media, different specimen's shapes, and under different quenching conditions. Analysis of the quenching results obtained from sound-emission signals during the quenching process can be confirmed by variations of residual stresses and hardness in the cross section. The results lead to the applicability of the new approach to the control of the hardening processes of steels.     

Distortion behaviour of gear parts due to carburizing and quenching with different quenching media

Two types of gear parts (wheels and pinions) made from low carbon nickel containing structural steel 18CrNiMo7-6 were gas carburized to a standard case depth of 0.7 mm, nitrogen gas- or oil-quenched and tempered to a resulting surface hardness of 60 HRC. The dimensional (shrinkage, growth) and shape distortion (ovalization, out-of-flatness, teething deviations in transversal as well as longitudinal direction), caused by these treatment methods, were measured. Also the effect of position in the test batch on the distortion and core hardness was assessed, in order to find out a relationship between these parameters and a possibility to optimize the process in future.     

连铸中间包焊接残余应力数值模拟

使用有限元法模拟了中间包焊接残余应力分布,结果表明,中间包焊接后在焊缝位置形成了较大的残余应力,残余应力峰值约672 MPa,已经达到材料屈服极限;在中间包吊耳和背部应力集中较为明显,说明在这些位置焊接裂纹倾向较大;在中间包背部,焊接残余应力关于中间包中面近似成对称分布,在中部和两侧焊缝残余应力最高,等效应力可达约40...     

高速齿轮离心应力的估算

从高速齿轮结构特点出发 ,提出了计算离心应力的近似模型。作者以弹塑性力学为基础 ,推导出了齿轮轴和整体式齿轮的离心应力计算公式 ,得到了其弹性极限转速的表达式。计算实例表明 ,在高速齿轮传动设计中建议考虑离心应力的影响。     

采煤机行走部大模数齿轮传动系统开发与应用

针对大采高采煤机行走部齿轮传动系统存在强度不足的问题,开发了30 mm大模数齿轮,校核了齿根弯曲强度和齿面接触强度并进行了修形处理。结果表明,大模数齿轮强度较为安全,优化后的齿面强度增加,应力分布更均匀,均载效果更好。     

Effect of Aqua Blasting,Sandblasting and Laser Engraving on the Corrosion Resistance of Type 316 Stainless Steel

The goal of this paper is to advance our understanding about the influence of commercial surface finishing treatments on microstructure development and corrosion resistance of a type 316L stainless steel. Aqua blasting, sandblasting, and application of a laser barcode engraving treatment were investigated using Focus Ion Beam, X-ray phase analysis, X-ray residual stress measurements, and surface roughness measurements. All surface microstructures were then assessed with atmospheric corrosion tests at 50?°C and 30?% relative humidity. Aqua blasting resulted in compressive surface residual stresses of ??500 to ??600 MPa, with no evidence of strain-induced martensite. Sandblasting led to compressive surface residual stresses of ??700 MPa, also with no evidence of strain-induced martensite. The samples subjected to laser engraving exhibited a recrystallized near-surface microstructure, with tensile surface residual stresses in the order of?+?500 MPa.     

SCR7000连铸连轧铜杆扭转裂纹的关键影响因素

针对SCR7000工艺生产低氧光亮铜杆的扭转裂纹问题,采用SEM+EDS、OM等研究了铜杆中的杂质元素,中心与边部的晶粒尺寸及硬度差异,铜坯凝固组织异常等关键影响因素对扭转裂纹的影响。结果表明：铜杆扭转裂纹中存在Fe、Ni、Cr、Si等杂质元素的局部富集,产生了应力集中,诱导了铜杆表层的扭转裂纹。分析认为,这些杂质元素主要来自浇包、过滤器及钢溜嘴等材料的熔损;铜杆中心部位的平均晶粒尺寸、硬度与边部的差异大,导致扭转裂纹敏感性大,这是铜坯的入轧温度、轧制过程的铜杆冷却不合适、轧机与铜坯间的摩擦作用以及SCR7000工艺多道次轧制所致;铸轮结垢的严重程度与扭转裂纹的发生率存在明显的正相关关系,这是严重的铸轮结垢导致铜坯凝固组织异常所致。     

利用Pro/E Wildfire和CAXA进行渐开线直齿圆锥齿轮精确建模

基于Pro/E强大的实体建模功能和CAXA独特的零件图形库的特点,针对渐开线直齿圆锥齿轮模数从小端到大端连续变大的规律,通过将CAXA和Pro/E特有的功能有机的联接,给出了建立将渐开线齿廓和齿形精确实体建模的方法,提出了该法较比曲线拟合的精度要高。经过实例表明这种方法具有造型可靠、精确和快捷等特点。     

磨机传动小齿轮中频表面淬火

从增加抗疲劳强度及耐磨性以提高齿面的硬度着手,通过分析工艺试验并对现场做了跟踪调查,表明利用中频表面淬火的方法对提高磨机传动小齿轮的使用寿命是切实可行的。     

基于振动与声发射融合的采煤机截割部故障诊断研究

采煤机截割部传动齿轮的工作状态影响着传动系统的工作效率。对齿轮故障监测与诊断进行研究,采用CATIA建立故障齿轮模型,利用仿真软件ADAMS与COMSOL仿真齿轮啮合瞬间产生的振动与声发射信号,对信号进行特征提取,采用BP神经网络对采煤机截割部齿轮故障进行诊断。仿真结果表明,振动与声发射融合对微小齿轮裂纹的识别具有较高准确性,对采煤机故障诊断具有一定的指导意义。     

锥形齿轮轮齿开裂失效分析

锥形齿轮轮齿表面在检修时发现表层剥落。应用化学分析、金相检验、扫描电镜和硬度测试等断口分析方法对剥落的轮齿进行了分析。结果表明:齿轮的热处理组织形态基本正常,但组织粗大。齿轮开裂剥落的主要原因是轮齿中存在裂纹,在交变应力作用下扩展,直至表层剥落。     

基于材料弹塑性的齿轮齿条啮合动态接触研究

基于材料弹塑性及齿面摩擦的影响,建立了齿轮齿条的三维非线性有限元分析模型,并对运转过程进行动态接触仿真,得出纯弹性、弹塑性材料及有、无摩擦4种情况下齿轮齿条的时变接触力、时变接触面积及动态应力,并与Hertz理论计算得到的应力值进行对比分析。