冲击座铸造工艺设计及优化

介绍了冲击座铸件的结构及其工艺设计,包括每型件数、浇注系统形式及内浇道、横浇道和直浇道的截面积、浇注时间、冒口及冷铁设计等。初始铸造工艺只采用冒口补缩,模拟发现该工艺未能完全消除缩孔缺陷,据此对铸造工艺进行了改进,在孤立热节区设计冷铁。对改进后的铸造工艺进行模拟,结果显示,缩孔缺陷已完全可以消除。     

Kinematics of the trunk in sitting posture: An analysis based on the instantaneous axis of rotation

This paper presents a new approach for analysing trunk kinematics in sitting posture based on the characterisation of thorax and pelvis motion by means of ranges of motion and instantaneous axes of rotation (IAR). These variables are estimated from videophotogrammetric data. An experiment was carried out in order to analyse three motions associated with the flexion–extension movement: the absolute motions of the pelvis and thorax and the relative motion between the thorax and pelvis. The results obtained suggest a sequential activation of lumbar vertebrae in the flexion–extension motion. On the other hand, the location of the pelvis IAR shows that the movement of the pelvis on the seat is not just a rolling motion but a rolling with some level of sliding. Finally, the location of the IAR in the thorax-pelvis relative motion shows a mismatch between the trunk IAR and the backrest axis of rotation in several office chairs. The proposed technique provides a new approach for the kinematic analysis of sitting posture. The results can be applied to the improvement of biomechanical models of seated posture as well as to define some design criteria of work seats based on the fit between the trunk and backrest movements.     

可转位气门座铰刀的使用性能

为了研究可转位气门座铰刀修理气门座的可行性，对铰削过程中的轴向力及扭矩、加工质量、铰刀寿命和经济性进行了试验研究。结果表明，采用新结构铰刀修理气门座，其使用性能和经济性均优于现有铰刀，适于我国国情，具有良好的应用前景。     

Overload analysis and Je-based fatigue life prediction of spot-welded auto seat belt anchors

We demonstrate the validity of J_e, which comprehensively describes the effects of specimen geometry and loading type, in predicting the fatigue life of auto seat belt anchor panel. We first simplify the heat‐affected zone model to reduce the number of finite elements. We then establish finite‐element models reflecting the actual overload behaviour of three types of seat belt anchor specimens. Using elaborate finite‐element models, we obtain the effective crack‐driving parameter J_e composed of its ductility‐dependent modal components. It is confirmed that the J_e concept successfully predicts the fatigue life of multi‐spot‐welded panel structures represented by auto seat belt anchors here.     

462Q无铅汽油汽车发动机排气阀座圈的研究

对铁基粉末冶金无铅汽油汽车发动机排气阀座圈进行了研究。采用向某种预混粉 (QMP -MP -VRC0 2 0 1)中添加Cu ,Co ,WC ,MnS等合金粉末的方法 ,在传统压烧粉末冶金工艺下对其成分、工艺和性能等进行了试验研究。通过正交试验 ,确定了最优的成分 (5C - 6Co - 0 8MnS -余为预混粉 )和烧结工艺 (115 0℃× 2h)。试制产品通过了 30 0h的台架试验和装车试验。文中讨论了合金元素、烧结工艺、组织结构等对排气阀座圈性能的影响     

The complete sequence of the 8.2 kb segment left of MAT on chromosome III reveals five ORFs, including a gene for a yeast ribokinase

We report here the DNA sequence of a segment of chromosome III extending over 8.2 kb. The sequence was determined using the random clone strategy followed by oligonucleotide-directed sequencing. The segment contains five long open reading frames, YCR521, 522, 523, 524 and 526, with only short distances between them. YCR523 (333 codons) encodes a ribokinase, a new function for yeast. YCR526 originates inside the MAT cassette, which is in continuity with the present segment, and extends over 358 codons outside of MAT. YCR524 (923 codons) codes for a putative membrane protein. YCR521, 522 and 524, have each been disrupted by insertion of a URA3 cassette and are non-essential genes. An active ARS element is located within YCR523 or its vicinity.     

座椅悬架软件的设计

利用AutoCAD和I-DEAS各自的优点,分别建立了座椅悬架的二维图形库和三维图形库,并建立了管理它们的数据库。然后利用接口语言,将二维图形库、三维图形库和数据库联系起来,形成座椅悬架设计的通用软件包。这样丰富了座椅设计理论,为座椅的使用和推广起到了一定的促进作用。     

轮胎带束层裁断机裁刀装置的改进

此裁刀装置主要应用在半钢子午线轮胎带束层裁断机方面,是在现有轮胎带束层裁断机裁刀装置的基础上,对上刀压板、下刀座、弹簧压板及裁刀安装尺寸进行了改进,有效的防止了下刀座产生移位及裁刀变形。保证了上刀与下刀的正常裁切,从而发挥裁刀最大使用次数,提高工作效率,降低裁刀维护费用,提高产品质量,减少废料发生。     

160t铁水包主副钩天车技改电子秤的设计

本文简单介绍了行车电子秤常用的秤体结构形式,平衡架下面安装鱼背桥式传感器是一种常用的天车技改方案,并着重分析了南通宝钢钢铁有限公司160t铁水包主副钧天车技改电子秤的设计——采用超薄型轴座式称重传感器的设计解决平衡架下面无法安装鱼背桥式传感器的难题。     

发动机缸盖加工关键工艺研究

汽车机缸盖是发动机上的关键部件之一,其加工精度的好坏将直接影响发动机的整体性能.提高气门座圈和导管孔的加工精度不但能延长发动机的使用寿命,而且能够降低发动机的油耗.针对发动机缸盖上关键特征气门座圈和导管孔的加工,对发动机缸盖气门座圈和导管孔加工工艺的发展、加工过程中常用的加工刀具、加工过程中常用的冷却方式、切削参数的选择和主轴的刚性对特征加工精度影响这五个主要因素进行了研究和分析,并给出了提高气门座圈和导管孔的加工精度的建议.