滚动轴承在曲轴磨床改造中的应用

正我公司是发动机曲轴专业生产企业,年产各类型号曲轴能力达百万根。随着科学技术的进步,对发动机零部件的技术要求越来越严,诸如曲轴轴颈形状公差圆度0.005mm,圆柱度0.01mm,止推挡距尺寸公差0.047mm。以此便知,在其加工工艺中,轴颈磨削是至关重要的工序,我公司从采用普通曲轴磨床到现今高端数控CBN磨床,从国产到进口,     

一种内锥形貌误差的激光测量方法

常见锥度测量方法有圆锥量规测量,平台法测量,坐标法测量及用带圆周分度装置的仪器测量等。目前,内锥的数字化测量,多数是通过三坐标测量仪来实现。但三坐标测量仪存在成本高,对工作环境要求高,操作较烦琐,以及不利于自动化测量等不足。本文设计了一种内锥激光测量仪,研究了测量原理和测量算法,实验结果和误差分析证明了结构和原理的有效性。     

客机机身剖面外形的优化设计

机身剖面外形设计是客机总体设计的一个重要方面。在分析机身剖面类型和设计流程的基础上,研究了客机机身剖面的参数化设计方法。根据客舱段的主要控制参数,利用优化方法对机身剖面外形参数进行优化设计,开发了快速生成最优客舱剖面外形的计算程序,为客舱设计提供了一个工具,应用这一设计工具进行客舱剖面外形设计,可以有效缩短设计时间。     

微反应器流道内单气泡逸出动力学模拟

采用VOF方法,对不同流道结构下液体通流微小通道内壁面逸出气泡的形成、生长及脱离运动进行了数值模拟,讨论了槽道高宽比对气泡动力学行为的影响。结果表明:流道截面积不变时,气泡的脱离体积、脱离时间随槽道高宽比的减小呈现先增大,后减小的趋势,当高宽比为2时,气泡的脱离体积、脱离时间、槽道容积含气率和流动阻力因子均达到最大值。     

基于计算机的水下湿法焊缝成形问题分析

通过实验得到空气中和水中同样焊接工艺参数下焊接焊缝的熔宽和熔深,对比两者的不同,说明水会对焊接电弧和电弧能量产生影响。在同样的焊接工艺参数下,采用水下湿法进行焊接得到的焊缝熔宽更窄,熔深更深。随后又通过模拟得到4种焊接工艺参数条件下的焊缝尺寸数据,并与实验结果进行了对比,说明模拟方法能够较为准确的确定其焊缝形状尺寸。     

AZ80镁合金半固态组织的等温演化研究

对半连续铸造和热挤压态AZ80镁合金进行半固态等温处理,研究了其微观组织的演变规律和α-Mg晶粒尺寸及形状系数与工艺参数的定量关系。结果表明,相同参数条件下,挤压AZ80镁合金经半固态等温处理后,α-Mg晶粒更圆整,晶粒尺寸分布更均匀;其α-Mg晶内液相出现机制以溶质元素富集和高能储备导致晶内局部优先熔化为主;而半连续铸造AZ80镁合金半固态等温处理过程中,α-Mg晶内液相出现机制以枝晶臂合并导致液相进入晶内为主。挤压AZ80镁合金经不同参数的半固态等温处理后,α-Mg晶粒尺寸均符合高斯分布;其较佳的半固态处理工艺参数为570℃保温20min,此时固、液相的相对分布更均匀,α-Mg晶粒平均形状系数为0.86,且多集中于高系数区。     

Numerical analysis of transient keyhole shape in pulsed current plasma arc welding

Based on the characteristics of ＂one keyhole in a pulse＂ in pulsed current plasma arc welding （PAW） , the transient variation process of weld pool in a pulse cycle is simulated through the establishment of corresponding heat source model. And considering the effects of gravitational force, plasma arc pressure and surface tension on the weld pool surface, the dynamic change features of the keyhole shape in a pulse cycle are calculated by using surface deformation equation. Experiments are conducted and validate that the calctdated weld fusion line is in good agreement with the experimental results.     

Finite Element Analysis of the Microstructure–Strength Relationships of Metal Matrix Composites

The influence of the shape and spatial distribution of reinforced particles on strength and damage of metal matrix composite （MMC） is investigated through finite element method under uniaxial tensile, simple shear, biaxial tensile, as well as combined tensile/shear loadings. The particle shapes change randomly from circular to regular n-sided polygon （3 ≤ n ≤ 10）; the particle alignments are determined through a sequentially random number stream and the particle locations are defined through the random sequential adsorption algorithm. The ductile failure in metal matrix and brittle failure in particles are described through damage models based on the stress triaxial indicator and maximum principal stress criterion, respectively, while the debonding behavior of interface between particles and matrix is simulated through cohesive elements. The simulation results show that, under different loadings, interface debonding is the dominated failure mechanism in MMCs and plastic deformation and ductile failure of matrix also play very important roles on the failure of MMCs.     

40CrNiMo高套筒锻造工艺的研究

自由锻企业经常要生产一些批量较小．力学性能要求高,同时又不允许采用无缝钢管而必须锻造成形的高套筒形锻件．这类锻件的几何形状特点是高径比较大,同时壁厚又较薄．材质多采用优质合金钢如40CrNiMo．锻造成形的难度比较大,一直是自由锻生产中的难题。