零件设计与热处理工艺性

本文从零件的材料选择、结构设计、热处理技术要求的确定和标注等方面较详细地阐述了设计与热处理工艺性之间的关系,以充分地发挥零件的机械性能。     

热处理工艺在提高金属零件的制造水平中的作用

金属零件是现代的工业建设的砖瓦,零件的制造对于工业的发展有着重要的作用,因此,工业建设中,如何提高金属的零件制造工艺水平就成了不可或缺的研究课题。而热处理环节则是制造加工金属零件的重要步骤,对于提高金属零件的质量和制造水平都有着巨大的影响。本文通过对热处理技术的简单介绍,粗浅的对热处理提高零件加工制造的作用进行了讨论。     

高速钢高温轴承零件的热处理

在高温下工作的轴承零件，除要求保持较高的硬度外，还必须具备耐磨损、耐疲劳、抗氧化、耐腐蚀、执冲击、良好的尺寸稳定性以及较好的被加工性能。高速钢正是兼备上述各种性能为数不多的钢种之一。以下简介高速钢高温轴承零件的热处理工艺。     

热处理工艺对于提高金属零件制造水平的意义分析

随着科学技术的发展和社会的不断进步,在现代化工业生产过程中,对金属零件的制造过程的研究不仅十分重要,而且相当关键,如何实现金属零件制造水平的有效提高已经成为相关领域的关注热点。热处理工艺可在确保金属零件原形状及整体成分不变的基础上对零件内部较为特别的结构进行改造,从而实现金属零件使用性能的进一步完善。鉴于此,本文对热处理工艺进行了分析,并重点就其提高金属零件制造水平的作用及意义进行了分析。     

热处理工艺在提高金属零件的制造水平中的作用

本文说明了热处理工艺的金属零件制造中的作用。金属零件的加工制作是需要高精度高准确率的,其操作流程和手段都依赖于精密的仪器,应当努力提升零件的制作水平,在制造工艺上,有效而主要的方式之一是热处理工艺,这能够显著提升制造的质量,所以,在设计工作中就体现了热处理的存在,通过它能够带来较为强大的性能的提升,但是热处理工作本身应当被良好的控制和使用,不当的使用会带来反面效果。所以,人员应当根据所掌握的零件性能等准确选择热处理的现行状态。并通畅工艺工序,严格按照标准来完成工作。达到最好的效果,提升金属零件的最终状态。     

热处理工艺在提高金属零件的制造水平中的作用

本文从三个方面论述了热处理工艺在提高金属零件的制造水平中的作用。     

用预回火法消除长针类零件的热处理变形

纺织机械上采用的长针类零件制作中多采用冷有加工而产生残余应力，在随后的热处理器容易发生弯曲变形，本文以Ｔ１０Ａ缝针为例，介绍了用预回火方法消除此类变表的实验，证明了预回火法行之有效，具有实用价值。     

论皮革服装加工余量的科学选定

本文主要研究影响皮革服装缝制加工余量的因素，加工余量确定的依据，从反正确选定加工余量对提高企业经济效益的作用。     

热处理圆盘豆木材的热分析研究

以过热蒸汽为传热介质和保护性气体,在热处理温度为160℃、180℃、200℃和220℃,热处理时间均为4h的条件下对圆盘豆木材进行高温热处理后,采用综合热分析仪对圆盘豆热处理材和未处理对照材进行热重分析和差示扫描量热分析,结果表明,热处理使木材的颜色加深、尺寸稳定性增强、强度降低.强度降低的主要原因是热处理使木材中的半纤维素、纤维素、木素发生剧烈的热降解反应     

薄壁类零件变形的综合处理

为了防止薄壁类零件变形 ,分析了导致变形的各种因素 ,并针对易产生的问题 ,分别从工艺、金属切削、校直等方面提出了解决变形的措施 ;采取这些措施 ,使不同类型的薄壁类零件的精度、稳定性得到普遍提高。     

异形薄片零件的线切割加工工艺

针对异形薄片零件的线切割加工过程中的问题，从防止加工变形，加工路线制定等方面通过实例介绍了其加工工艺，提供了有关加工参数及操作注意事项。     

寻找活着的答案

在全国各地做培训的时候,常会有学员问我:于老师,我工作挺努力的,为什么就是得不到公司重用呢?也有学员问:于老师,为什么我这么努力,可公司总是不给我加薪呢?我的回答往往让他们大吃一惊,我反问道:你们知道努力和奴隶的区别吗?我告诉大家,奴隶是世界上最努力的人,不过他的努力是被动的,不是心甘情愿的。而从内心深处生发出的努力,则会得到别人的尊重、同事的认可、对手的敬畏、家人的自豪。这些收获     

Growth of heat-treated enterotoxin-positive Clostridium perfringens and the implications for safe cooling rates

Clostridium perfringens 790-94 and 44071.C05 carrying a chromosomal and a plasmid cpe gene, respectively, were used to determine differences in heat resistance and growth characteristics between the genotypes. Heat inactivation experiments were conducted using an immersed coil apparatus. Spore germination, outgrowth, and lag phase, together named GOL time, as well as generation times were determined during constant temperatures in fluid thioglycollate (FTG) medium as well as in vacuum-packed, heat-treated minced turkey. GOL time and growth were also monitored during cooling scenarios from 65 to 10 degrees C for 3, 4, 5, 6, and 7 h in vacuum-packed, heat-treated minced turkey. Spores of strain 790-94 were approximately 10-fold more heat resistant at 85 degrees C than those of strain 44071.C05, and strain 790-94 also had a higher temperature growth range in FTG. The higher growth range for a chromosomal enterotoxin-producing CPE+ strain was confirmed using two other strains carrying a chromosomal (NCTC8239) and plasmid (945P) cpe gene. Moreover, strain 790-94 had shorter GOL times at 50 degrees C in turkey and approximately half the generation time compared with strain 44071.C05 at temperatures > or = 45 degrees C in both FTG and turkey. Strain 790-94 increased with 0.3, 1.0, 1.7, and 2.0 logs, respectively, during cooling from 65 to 10 degrees C in 4, 5, 6, and 7 h, which was significantly higher than for strain 44071.C05. A maximum acceptable cooling time of 5 h between 65 and 10 degrees C is suggested.     

The effect of nisin on the keeping quality of reduced heat-treated milks

Milk was subjected to a combination process involving reduced heat treatment (RHT) of 117 degrees C for 2 s and nisin (75 and 150 IU ml(-1)). The microbial activity and other quality aspects were compared with a RHT control (without nisin) and with a ultrahigh temperature (UHT) milk processed at 142 degrees C for 2 s. Nisin was found to inhibit microbial growth for products stored without refrigeration, and RHT-nisin samples stored at 30 degrees C showed very low spoilage rates during 150 days, although not low enough to satisfy requirements for commercial sterility. RHT-nisin samples could be distinguished from and were preferred to the UHT control. Significant browning occurred during storage at 30 degrees C and above but was less in the RHT-nisin milk samples compared with the UHT milk. In RHT-nisin milk samples stored at 20 and 10 degrees C, no microbial activity could be detected in most samples after storage for 1 year. The effectiveness of this combination of RHT, nisin, and low storage temperatures against gram-positive spore-forming bacteria suggests potential for use of nisin in extended shelf life products.     

The effect of a natural antioxidant on the stability of heat-treated paprika

The colour loss occurring in a paprika made from the dehydrated fruits of pepper, Capsicum annuum L. var. Ocal (control), was compared with the colour lost by a similar paprika submitted to an industrial sanitation process involving water vapour. The heat treatment resulted in a considerable greater loss of colour when the paprika was stored at 25 °C in different relative humidities (0, 23, 57 and 75%) compared with the control paprika. The study also analysed the effect of adding a natural antioxidant (rosemary extract at 1%) to the heat‐treated product. In this case, colour stability increased significantly in all the conditions assayed; the lower the humidity, the greater the increase in stability.     

The vitamin B6 allowance of hypertension patients and the effect of dietotherapy

A total of 111 patients with essential hypertension (the II stage) and obesity (the II degree) were investigated for providing with vitamin B6. The functional methods used for the vitamin assay (ACT activity of red blood cells and pyrodoxale-5-phosphate effect) have revealed significant vitamin B6 deficiency in 81.1% of the patients. Vitamin B6 deficiency was intensified in the course of the dietotherapy. Correction of vitamin B6 deficiency with a therapeutic dose of pyridoxine (20 mg/day) during 20-22 days, in the presence of the diet, has promoted optimization of providing with vitamin B6: normalization of pyrodoxale-5-phosphate effect. The hypotensive effect and decrease of excessive body mass in patients who received dietotherapy and pyridoxine (20 mg/day) were more pronounced than in those who received the same diet and the multivitamin "Undevitum".     

捍卫心血管“Benecol”值得期待——Raisio生命科学公司高层访谈

<正>随着生活水平的提高以及饮食习惯的改变,中国消费者对高胆固醇食物的涉入量不断增加,使得心血管疾病成为健康的主要“杀手”。由于缺少迅速且方便地降低胆固醇的方法,许多人对此一筹莫展。近日,名为Benecol 的添加剂产品强势登陆中国市场,以迅速有效地降低胆固醇的“招牌”吸引了诸多关注目光,在某些消费市场,它几乎成丁降低胆固醇的代名词,这不啻为一剂中国配料市场的“强心针”。或许在不久的将来,它会引发一场功能性食品的革命。     

羊绒产业链亟待完善

我国羊绒产业规模发展的高峰即将过去，以后将是中国羊绒企业品牌发展的黄金时期，但这需要一个重要的前提。那就是羊绒产业链必须良性、协调发展，产业链上的每一个环节都有责任维护产业链的健康发展。[编者按]