一种全新的打孔工艺——多向液压冲孔

目前国内外在金属管件上打孔,常规的方法有钻孔和冲孔.此文所论述的是一种目前国内文献尚无记载、实践尚无运用的全新的工艺——多向液压冲孔.通过实践运用,证实了在弯曲长钢管上打孔,多向液压冲孔工艺较之钻孔与冲孔工艺,更具有大幅度的提高产品质量,数十倍的提高工效,能实现产品自动化流水线生产等优势,值得大力推广应用.     

管件冲孔的特种工艺方法

介绍管件冲孔三种特种工艺:无凹模冲孔;局部无凹模冲孔;聚氨酯橡胶冲孔。分析比较了这三种工艺的工作机理及实际运用状况。     

罩壳锥面侧向冲孔模

介绍了锥面上冲孔用斜楔块代替立式凸模；中JL．改善了凸模的受力状况．并提高了模具寿命。     

钢板翻边成形预冲孔直径的确定

此文以198909K轴承刚性圈为例,介绍了钢板制件在冷冲压翻边成形工艺中预冲孔直径的确定方法。该方法是通过一次工艺试验,将用理论计算方法得到的预冲孔直径加工出的工件高度与产品要求进行比较,用其差量△H去逼近正确的预冲孔直径。采用该方法,可以保证翻边成形后工件的尺寸要求,对于精度高、批量大的产品加工有很大意义。     

桩基冲孔施工对埋地原油管道安全影响模拟研究

采用三维有限元法模拟了泵房桩基单机冲孔施工过程,研究了单机冲孔的冲击荷载作用下深埋原油管道的动力反应,根据原油管道动位移、动应力计算结果,评价了泵房桩基单机冲孔施工过程中原油管道的安全性。     

大孔径冲孔翻边一次成型的设计

此文主要根据冲压件“前顶梁”冲孔翻边一次成型模设计的实践经验,提出大孔径冲孔翻边一次成型的工艺分析和计算及典型结构的设计,突破了冲孔与翻边同时进行只能在Φ8以下圆孔翻边的局限,并成功地一次试模合格,为类似的圆孔翻边在Φ8以上提供了宝贵的经验。     

筛子冲孔工艺改进及模具设计

介绍了一种岔开冲孔工艺与一种冲压小尺寸筛类零件格栅的五工位连续模.     

等面积法确定翻边预冲孔直径

介绍了钢板翻边工艺中预冲孔直径的等面积计算与工艺验证结合的确定方法。采用这种方法 ,可以保证翻边成形后工件的尺寸要求 ,对于精度高、批量大的产品加工很有意义     

冲孔件质量控制四例

本文结合4个典型实例,对生产中因受落枓、弯曲、拉深等其它冲压工序的影响而产生的冲孔件质量问题进行了分析。介绍了在生产现场解决问题的方法和防止这类废次品产生的措施。根据对具体实例的分析、文章总结出了有关冲孔件质量控制的一些要点。     

电炒锅底盖成形模具设计

本文主要介绍“电炒锅底盖”双向引伸、成形、冲孔复合模具。此副模具可在单动冲床上使用。     

调心滚子轴承保持器落料成形复合模的设计

介绍了22224C/W33调心滚子轴承保持器落料成形冲中心孔复合模的设计方案、结构和工作原理。此复合模经使用表明可极大地提高生产效率,并保证产品合格率。     

125型摩托车铝合金车轮的液态挤压成型

分析了125型摩托车铝合金车轮的特点,介绍了车轮液态挤压成型模具的设计及液态挤压成型的整个工艺和生产过程中应注意的问题.     

改变压铸工艺 提高铸件质量

在生产实践的基础上 ,针对铸件的特点 ,通过改进浇注系统 ,提高压铸件的质量 ,分析了 3种压铸工艺的优缺点。     

后扣板冷挤压工艺及模具

此文分析了产品成形的特点,模具承载的负荷特点,从而在成形工艺上、润滑上、模具结构及选材上采取了相应的措施.用H-4水基高分子润滑剂和3Cr2W8V制作冷挤压模都取得了明显效果.     

Mechanism on minimization of excess sludge in oxic-settlinganaerobic (OSA) process

The oxic-settling-anaerobic (OSA) process is a promising wastewater treatment technique for efficiently reducing sludge production and improving the stability of process operation. In this paper, the possible factors of sludge reduction such as sludge decay, uncoupled metabolism, and anaerobic oxidation with low sludge production were discussed in the OSA process. It has been confirmed that sludge decay is the decisive cause in the OSA process, accounting for 66.7% of sludge production reduction. Sludge decay includes hydrolysis and acidogenesis of dead microorganisms and particle organic carbon adsorbed in sludge floc and endogenous metabolism. By batch experiments, it has been proven that there is energetic uncoupling in the OSA system since microorganisms were exposed to alternative anaerobic and aerobic environment. It accounts for about 7.5% of sludge production reduction. Soluble chemical oxygen demand (SCOD) released from the anaerobic sludge tank in the OSA process was used as the substrate for cryptic growth. The substrate was used for anoxic denitrifying, anaerobic phosphorus release, sulfate reduction, and methane production. These anaerobic reactions in the sludge anaerobic tank have lower sludge production than in the aerobic oxidation when equivalent SCOD is consumed, which may lead to approximately 23% of sludge reduction in the OSA process. It has been concluded that multiple causes resulted in the minimization of excess sludge in the OSA system. The microbial community structure and diversity of sludge samples from the CAS (conventional activated sludge) and OSA systems were investigated by 16 SrDNA PCR-DG-DGGE (polymerase chain reaction-double gradient-denaturing gradient gel electrophoresis). DGGE profile and cluster analysis showed more abundant species in the OSA system contrasting to microbial communities in the CAS system.     

摩托车用无内胎车轮轮辋滚形工艺

给出了根据一种无内胎车轮轮辋滚形工艺各道滚形变形量确定方法而设计的模具 ,生产出的轮辋尺寸精度高、圆角减薄量小 ,且对各种型号的车轮通用性好 ,具有较大的现实意义。     

Fertilizer market reforms and factors influencing fertilizer use by small-scale farmers in Bénin

Bénin, like other countries in sub-Saharan Africa, has initiated programs to reform agricultural input and output markets. While the impact of the reform programs has been different for each country, it is commonly observed that impact at the farm level has been less than anticipated. A central theme of this paper is to assess the impact of fertilizer market reforms on the fertilizer market structure and fertilizer use for both food and export (cotton) crop production in Bénin. This analysis of farm-level policy impact is based on data from 899 farm households randomly selected and interviewed in all six départements of Bénin in 1998/1999. Results of the study show that there have been only insignificant changes in the fertilizer market structure. Access to fertilizers has not improved; prices for fertilizer have risen in real terms, resulting in application rates lower than that recommended by extension agents. The effects of the reform programs are vital for investment decisions and provide lessons for introducing alternative approaches for improving soil fertility or management. Since 1992, 54% of farmers find maize (Zea mays L.) production more profitable, while 38% reported that cotton (Gossypium hirsutum L.) production has become more profitable. As a result of the mixed effects of the fertilizer market reform program on the level of fertilizer use and profitability, there is need to develop efficient soil fertility management strategies for small-scale farmers. Such strategies should incorporate the use of complementary inputs, such as seeds with a high level of response to the balanced nutrient package.     

A Comparison of Pin Actuation Schemes for Large-Scale Discrete Dies

Reconfigurable discrete die tooling is attractive for reducing the lead time, initial costs, and recurring costs associated with stretch forming of sheet metal parts such as aircraft body panels and wing skins as well as automotive and marine components. Current tooling for the stretch forming process requires substantial lead time for fabrication and is inflexible and expensive. To develop discrete die tooling for stretch forming, three different discrete die designs have been proposed, and small-scale prototypes of each have been built. In this paper, the three designs are compared to each other in terms of performance criteria, including pin positioning accuracy and repeatability, setting speed, suitability for a production environment, fabrication costs, manufacturability and maintainability, and maximum forming load capacity. The advantages and disadvantages of each design are also discussed.     

曲壁薄管的滚压成形工艺及模具

在现代的生产、生活中 ,板金零件的应用越来越广泛 ,零件的形状更具特色 ,而零件的成形工艺则越来越多样化。以仿古铜鼓为例 ,介绍了曲壁管在车床上滚压成形的工艺技术及其模具结构 ,并分析了工艺特点和应用中应注意的问题     

EG-510PCB印制板复合复位模设计

此文分析了加工EG-510PCB印制板模具的设计方案。用大间隙的复位冲裁间隙和固定弹顶装置来解决八拼板零件的复位问题,满足了模具使用上的要求。并采用一次成形的复合复位模结构,既保证了产品的质量,又提高了生产效率,同时降低了生产成本。