机床产品创新和开发流程探究——“森精机”案例分析

[编者按]在2008年10月刚刚结束的CIMES 2008上,森精机制作所携其4款机型参展,吸引了大批专业观众.其融合了重心驱动、直接驱动马达、箱中箱结构及八角型滑枕等一系列森精机独创技术的NMV5000 DCG立式加工中心成为展览的一大亮点.为此,本刊特邀黄仲明、田也壮、张曙3位专家共同撰稿,解析森精机的机床产品创新与开发流程,以飨读者.     

Source investigation of impulsive He-rich particle events

We have investigated the source characteristic and coronal magnetic field structure of six impulsive solar energetic particle (SEP) events selected from Wang et al. [Wang, Y.-M., Pick, M., Mason, G.M. Coronal holes, jets, and the origin of ³He-rich particle events. ApJ 639, 495, 2006] and Pick et al. [Pick, M., Mason, G.M., Wang, Y.-M., Tan, C., Wang, L. Solar source regions for ³He-rich solar energetic particle events identified using imaging radio, optical, and energetic particle observations. ApJ 648, 1247, 2006]. Some results are obtained: first, 2 events are associated with wide (≈100°) CMEs (hereafter wide CME events), another 4 events are associated with narrow (?40°) CMEs (hereafter narrow CME events); second, the coronal magnetic field configuration of narrow CME events appear more simple than that of the wide CME events; third, the photospheric magnetic field evolutions of all these events show new emergence of fluxes, while one case also shows magnetic flux cancellation; fourth, the EUV jets usually occurred very close to the footpoint of the magnetic field loop, while meter type III bursts occurred near or at the top of the loop and higher than EUV jets. Furthermore, the heights of type III bursts are estimated from the result of the coronal magnetic field extrapolations.     

Creep Behaviors of FGH95 Powder Ni-Base Superalloy

This article makes an investigation into the creep behavior and deformation features of FGH95 powder Ni-base superalloy by means of creep curves and microstructural observation. Results show that this superalloy exposes obvious sensibility to the applied temperature and stresses in the experimental range. Microstructure of the alloy consists of γ′ phase of various sizes and dispersed carbide particles precipitated in the wider crystal boundaries between the powder particles. During the creep, the deformation of the alloy occurs in the form of single- or double-oriented slipping inside the grains, and some of the finer carbide particles are precipitated near the slipping traces. The wide grain boundaries might be broken into the finer grains due to severe deformation. The deformation mechanism of the alloy during creep is thought to be the activation of dislocations of double-oriented slipping, including (1/2)<110> dislocation inside the γ matrix phase and <110> super-dislocation inside the γ′ phase. The formation of the stacking faults and (1/3)<112> super-Shockleys partial dislocation configuration is attributed to the decomposition of <110> super-dislocation in the γ′ phase.     

A novel autonomous self-assembly distributed swarm flying robot

Swarm intelligence embodied by many species such as ants and bees has inspired scholars in swarm robotic researches. This paper presents a novel autonomous self-assembly distributed swarm flying robot-DSFR, which can drive on the ground, autonomously accomplish self-assembly and then fly in the air coordinately. Mechanical and electrical designs of a DSFR module, as well as the kinematics and dynamics analysis, are specifically investigated. Meanwhile, this paper brings forward a generalized adjacency matrix to describe configurations of DSFR structures. Also, the distributed flight control model is established for vertical taking-off and horizontal hovering, which can be applied to control of DSFR systems with arbitrary configurations. Finally, some experiments are carried out to testify and validate the DSFR design, the autonomous self-assembly strategy and the distributed flight control laws.     

二维弹性圆柱涡致振动的尾涡模态

对均匀来流情况下Re数为200的二维单自由度弹性支撑圆柱涡致振动问题进行了数值模拟。采用时空有限元方法求解二维不可压N-S方程,利用新型显示积分方法求解圆柱振动方程,并用弹簧动网格技术实现网格更新。针对低折合阻尼比涡致振动,分析了不同圆柱自振频率下升力系数、阻力系数以及圆柱位移等参数的变化趋势,成功地捕捉了"锁定"、"拍"和"相位转换"等现象。讨论了圆柱脱落尾涡模态随时间的演变,观测到新的2P+2S尾涡模态,当圆柱振动幅值最大时,尾涡在下游不同位置可能出现2S、2P+2S和2P模态。     

固液混合火箭发动机固体燃料的燃速计算

分析了固液混合火箭发动机的燃烧特点、燃烧中气相过程和固体燃料内部的传热过程,利用由传热理论得出的固体燃料燃速公式和阿累尼乌斯(Arrhenius)燃速公式耦合计算,得到了燃速与氧化剂流率、轴向距离、装药初温和时间的变化规律.计算结果表明固体燃料燃速主要受氧化剂流率和轴向距离的影响,随氧化剂流率的增加而增加,随轴向距离的增加而减小.固体燃料燃速温度敏感性小,在设计发动机时可以不考虑装药初温的影响.利用热力计算得到了绝热燃烧温度与氧化剂流率和药柱长度的变化规律,绝热燃烧温度随氧化剂流率的增加存在一最大值.计算结果与相关文献的报道比较吻合,为进一步研究固液混合火箭发动机的燃烧及流动问题打好了基础.     

快响SAR卫星零多普勒波束中心姿态机动策略研究

传统偏航牵引方法采用惯性系下卫星轨道6要素推导得出姿态机动参数,在此方法中仅控制卫星主轴方向多普勒频率为0Hz,无法补偿SAR天线安装偏差和波束在天线内的方位距离向离轴角引起的斜距偏差和多普勒频率偏移,不能满足SAR系统时序设计需求和快响SAR卫星在轨实时处理器性能要求。因此,提出了地心固定坐标系中SAR天线波束指向零多普勒面内目标方向的姿态机动策略,使快响SAR卫星在轨实际波束中心多普勒频率为0Hz。该策略首先计算了基于场景目标的SAR总体设计的精确时序参数和观测参数,然后在地心固定坐标系中建立了波束中心多普勒频率为0Hz的SAR天线波束三轴指向模型,推导得出卫星三轴指向和姿态机动参数,并通过Matlab对该策略进行了仿真验证。结果表明,该策略可将多普勒频率由地球自转引起的29kHz、天线与卫星安装偏差引起的360Hz和波束方位向离轴角引起的3950Hz补偿至0Hz,同时将由天线与卫星安装偏差和波束距离向离轴角综合引起的波束中心偏离目标的斜距偏差6.28km补偿至米的量级。     

空间应用复合材料压力容器研制技术

综述了空间应用金属内衬复合材料压力研制技术，从性能优势，金属内衬，复合材料，试验四个方面给出了比较重要的技术信息，同时列举了国外空间系统应用的几个典型实例，并对中国研制空间系统应用复合材料压力容器提出了几条值得借鉴的经验。