数控编程在注塑模具制造中的应用

以实例说明了数控编程在注塑模具制造中的应用。     

基于参数化的塑料模具设计系统

利用塑料模具模架和标准件管理系统建立、管理模架和标准 数据库。在模具设计过程中通过该系统选用２模架和标准件,并将数据传递给参数化绘图系统,自动生成模架和标准件图形。本文以ＢＩ型两板模为例介绍该系统的组成和设计原理。     

OBJECT-ORIENTED NUMERICAL MANIFOLD METHOD

0INTRODUCnONNumericalmanifoldmelhod(NMM)isanewlydevelopedgeneralnumericalmethodbaseduPOnmathematicalmethod.FortheNMM,bothcontinuumanddiscontinuitiesarenatural.SothismethodisageneralnumericalmethodforsolvingtheproblemsthatcanbecalculatedbyaaM,DDAoranalyticmethod.ThismethodhasbeenaPPliedtorockengineeringwidely['~SJ.TOstudyNMMandPOPulallzethetwo-dimensionalproblemstothree-dimensionalproblemsconveniently,weintroducedtheObject-orientedPro~ng(OOP)intotheprogramdesignOftheNMManddetai…     

CSCW技术在模具CAD/CAE/CAM集成系统中的应用

由于影响其它产品的生产,模具工业在制造业中占据着举足轻重的地位,模具的制造过程牵涉到制造业的许多方面,因而先进的模具制造技术必须采用系统集成的方法,然而上前的模具ＣＡＤ／ＣＡＥ／ＣＡＭ集成技术缺乏及时的信息交流,从而降低了集成系统的效率,为了克服这一缺点,本文提出了一个基于ＣＳＣＷ环境的模具ＣＡＤ．ＣＡＥ．ＣＡＭ集成系统,并对系统中环境的构造、Ａｇｅｎｔ结构设计、任务关联和分解、产品数据管理等进行     

汉兵马俑的熔模铸造

简介了一种汉兵马俑的熔模铸造过程,给复杂和特殊结构及材质的铸件提供了一种可借鉴之方法。     

圆坯电磁软接触连铸结晶器高频磁场分布

通过实验检测和数值模拟方法研究圆坯电磁结晶器切缝形式、切缝宽度、切缝数量及切缝长度对圆坯电磁软接触结晶器内高频磁场分布的影响,为软接触结晶器优化设计提供磁场理论依据.结果表明:切缝数增加可提高透磁性和均匀性;增大缝宽对透磁性影响不明显,但降低均匀性;缝长只在一定范围内对透磁性有影响.     

臭氧处理不同含水量稻谷效果研究

利用正交设计,将含水量14.0%~17.0%的稻谷,用150~450 mg/kg的臭氧处理2~6h。结果表明：臭氧处理对稻谷品质指标影响小,臭氧处理后稻谷脂肪酸值为12.98~15.56 mg/100g、发芽率为87%~97%、品尝评分值为75~81分。臭氧处理浓度、处理时间和稻谷初始含水量对霉菌总数减量有极显著影响。臭氧处理后,霉菌总数减量6.9×103~2.1×104 cfu/g。以稻谷霉菌总数减量（Y）为因变量,以臭氧处理时间（X1）、稻谷初始水分含量（X2）、臭氧处理浓度（X3）为自?变量,进行多元线性回归分析,得到模型Y=1 602.78X1+1 448.15X2＋4.15X3-16 572.22。     

Occurrence and diversity of Bacillus cereus and moulds in spices and herbs

Spices and herbs can contain toxin-producing bacteria and moulds, which can cause health problems for consumers and contribute to food spoilage and shelf-life reduction. The aims of the present work were (i) to determine the occurence and levels of B. cereus and moulds; (ii) to charactize the incidence and diversity of B. cereus emetic toxin (ces, CER), and diarrhoeal toxin-encoding genes (entFM, nheA, hblC, cytK) and toxigenic potential of Hbl toxin-producing B. cereus strains. Black ground pepper samples showed the most contamination with the highest concentration of B. cereus 2.49 log₁₀ CFU/g. Moreover, cumin contained the most prominent mould concentration level of 3.6 log₁₀ CFU/g. The most common moulds were Aspergillus and Penicillium spp. Compared to packaging type, all products acquired from the local market, except curry for B. cereus, exchibited high concentrations of B. cereus and moulds. Four genes were identified – 96% of B. cereus strains contained entFM, 94% nheA, 56% hblC, 42% cytK. None of the samples contained emetic toxin-encoding genes (ces, CER). Toxigenic potential of Hbl toxin was found in 72% of B. cereus strains. Different temperature, moisture levels and hygiene practices were observed at places of sale in local markets thus facilitating contamination and development of moulds. Moreover, the presence of B. cereus and its ability to produce toxins in spices and herbs, may suggest the need to establish microbiological criteria for mould and spore-forming bacteria in spices and herbs.     

低压铸造工艺在D19下缸体中的应用

根据D19铝合金下缸体的铸件结构并结合生产现场的实际条件,采用了低压铸造工艺。采取了轴瓦面朝下,多浇口进料的方式,模具六开模,并设置了10路水冷和28路风冷。下缸体油腔泄漏率在3%以下,铸件合格率稳定在95%以上。     

Dynamics of phytosterol degradation in a bulk of rapeseed stored under different temperature and humidity conditions

Improper rapeseed preservation and storage after harvest may contribute to a reduction of phytosterol contents in the seeds. The aim of the study was to investigate the dynamics of phytosterol degradation in bulks of rapeseed stored under various temperature and water activity conditions. In the experiments a hazardous level of fungal infestation was considered to reflect the population of fungi colonizing seeds during vegetation and harvest at adverse weather conditions. Changes in phytosterol contents intensified with the increase in storage temperature and water activity in seeds. The temperature in the range of 12–24 °C and water activity in seeds a_w = 0.75–0.76 significantly limited phytosterol degradation (6.5% and 8% after 48 and 72 days of storage), whereas in seeds with a_w = 0.90 stored at 30 °C major phytosterol losses were observed (61% after 48 days of storage). Among the identified phytosterols the pattern of changes in campesterol content was similar to that for β-sitosterol, whereas brassicasterol degradation proceeded similarly as the reduction in avenasterol and stigmasterol levels. The degradation of stigmasterol, brassicasterol and avenasterol was more rapid than that of campesterol and β-sitosterol. Correlation analysis showed that acid value and seed germination may be used as predictive factors for phytosterol degradation. The correlation between the fungal population and phytosterol concentration was found only in seed samples, in which a substantial mould activity was observed (a_w ≥ 0.80 at t = 24-30 °C and a_w ≥ 0.86 at t = 12-18 °C). The results provide useful quality control points, which may be used to improve the existing postharvest management systems of rapeseed preservation and storage.