内冷铁在铸钢中小件上的应用

本文阐明了冷铁对铸件的影响、内冷铁在铸钢中的应用、采用内冷铁易引起的铸件缺陷及防止办法、内冷铁的设计与工艺处理等方面,说明合理的应用冷铁,可以显著地提高铸件的工艺出品率,对普通碳钢铸件,通常可提高10%左右。     

取消内冷铁 提高铸铁件质量

在铸铁件生产中使用内冷铁,容易形成熔合不良和气孔等缺陷,使铸件报废或者影响铸件的使用寿命。因此,铸件应尽量不使用内冷铁,以减少废品,保证产品的质量。经过几年的生产实践,我厂已成功地用外冷铁、补缩冒     

内冷铁在美国GE轴颈箱铸件上的应用

通过美国GE公司轴颈箱铸件内冷铁 生产试验，指出铸钢件内冷铁尺寸采用局热节模数法，按熔合状态计算或查列线图确定简便、准确、实用。内冷铁尺寸偏大，兼作拉筋使用时阻碍铸件收缩，易引起铸件裂纹。内冷铁被金属液包围状态比非包围状态引起铸件裂纹的倾向要小。     

内冷铁在厚大铸钢件生产中的应用

铸钢件生产中采用内冷铁是为了缩小铸件热节处的模数或缩小整个铸件的模数,减少冒口的体积或数量,消除缩孔、缩松缺陷. 1 内冷铁在54 t大板上应用的工艺设计 铸件尺寸为5 500 mm×2 860 mm×440 mm,模数Mc=22 cm,毛重54 t.冒口的个数为2,按放内冷铁和不放内冷铁工艺设计情况大不相同.     

苏联专家帮助我们在铁铸件上应用外冷铁

冷铁在铸造生产中的应用较广。在铸件上应用冷铁,能够防止缩孔、缩松和裂纹,保证得到组织细密而健全的铸件。一般说来,冷铁在钢铸件上用得比较普遍,但在铁铸件上并不广泛运用。在苏联专家库兹涅佐夫的直接帮助下,我厂在重要的铁铸件(水压试验高,表面满加工的)上,广泛的应用冷铁,消除了高压水压试验时发生渗漏的现象,大大提高了铸件质量。     

冷铁在铝合金熔模铸造中的应用

冷铁是防止铸件产生缩孔、缩松、针孔的有效工艺措施,在铝合金砂型铸造中,冷铁获得了广泛的应用。胃口和冷铁配合使用,对改善铸件的内在质量效果更佳。但是,在熔模精密铸造中,由于模壳需要经过高温焙烧且为热型浇注,所以,冷铁的使用受到了一定的限制,使用不广泛。     

内冷铁在4Cr5MoSiV钢液态模锻中的应用

本文介绍了内冷铁在4Cr5MoSiV钢液态模锻中的应用。为减少产品内部热节处出现缩孔和解决产品模膛沿凸模转角和底平面出现的裂纹,在凹模中安放内冷铁。结果表明采用内冷铁可有效防止产品热节处出现缩孔,并能减少铸件内部裂纹。     

灰铸铁厚大件砝码的铸造工艺

砝码重量50t、厚600mm，材料牌号为HT150。采用压边热冒口，铁液经由冒口进入铸件型腔。为防止表面缩陷、内部缩孔，曾在型腔内设置大量内冷铁，不但冷铁的准备和固定工作量很大，而且铸件质量并不好。后来考虑到该铸件厚大，且碳当量较高，自补缩能力较好，因而取消冷铁，获得了合格的铸件。     

铝合金铸造中冷铁作用效果的研究

通过试验与数值模拟相结合的方法,研究了冷铁厚度对T型铝铸件缺陷位置的影响,并根据T型铝铸件不同点处温度的变化来研究冷铁的有效作用距离.结果表明,当冷铁厚度增大到30 mm后,缺陷位置和冷铁的有效作用距离不再随着冷铁厚度的增加而改变.该研究对铝铸件的凝固过程中冷铁的应用具有参考作用.     

水基保护层涂料855W在铸件生产中的应用

采用醇基石墨涂料虽然能满足一般铸件表面要求,但是在厚大铸件(印刷机墙板和飞轮件)的放置冷铁部位却不能达到要求.如在放置冷铁部位表面产生形状不规则孔洞,冷铁与铸件粘合在一起等缺陷.通过水基保护层涂料与醇基石墨涂料的对比试验及实际应用表明,用水基保护层涂料取代传统涂料可以解决铸件冷铁部位的缺陷问题.     

纯铁γ—α转变机制求索

依据前人的实验数据，运用传统计算方法，对纯铁γ-α转变扩散机制进行了检验，结果表明：完成转变需用时间的理论计算值与实验值有3－4个数量级的差异。根据非切变相变大多存在非共格相界的特点，由相界原子参与相变的设想提出了存在非共格相界的非切变相变“相界与母相原子联动位移”机制。运用热力学基本原理对“联动”和新相连续长大的条件进行了简要分析。对固态相变的分类提出了质颖并建议把“扩散型相变”限定为新相与母相化学成分不同的相变。     

Turning Ideas into Reality

In his acceptance speech as the recipient of the 1983 Gold Award of the Affiliate Council of the Engineering Society of Detroit, Mr. Harwood directed a strong message to the U.S. technical community: “It is not ideas alone that move the world.” He addressed specific areas in which technical/scientific professionals must become involved in order to secure a position for the country in the international marketplace. Mr. Harwood received the Gold Award on February 23, 1983.     

Investigation into nitrided spur gears

The cold forging method has been widely used in industry to produce machine parts. In general, gears are produced by shaping or hobbing. One of the shaping techniques is precision forging, which has several advantages over hobbing. In the present study, cold forging of spur gears from Ti-6A1-4V material is introduced. To improve the surface properties of the resulting gears, plasma nitriding was carried out. Nuclear reaction analysis was carried out to obtain the nitrogen concentration, while the micro-PIXE technique was used to determine the elemental distribution in the matrix after forging and nitriding processes. Scanning electron microscopy and x-ray powder diffraction were used to investigate the metallurgical changes and formation of nitride components in the surface region. Microhardness and friction tests were carried out to measure the hardness depth profile and friction coefficient at the surface. Finally, scoring failure tests were conducted to determine the rotational speed at which the gears failed. Three distinct regions were obtained in the nitride region, and at the initial stages of the scoring tests, failure in surface roughness was observed in the vicinity of the tip of the gear tooth. This occurred at a particular rotational speed and work input.     

An investigation into roller burnishing

Burnishing, a plastic deformation process, is becoming more popular as a finishing process: thus, how to select the burnishing parameters to reduce the surface roughness and to increase the surface microhardness is especially crucial. This paper reports the results of an experimental program to study the influence of different burnishing conditions on both surface microhardness and roughness: namely, burnishing speed, force, feed, and number of passes. Also, it reports the relationship between residual stress and both burnishing speed and force. The residual stress distribution in the surface region that is orthogonally burnished is determined using a deflection etching technique. Mathematical models are presented for predicting the surface microhardness and roughness of St-37 caused by roller burnishing under lubricated conditions. Variance analysis is conducted to determine the prominent parameters and the adequacy of the models. From an initial roughness of about R_a 4.5 μm, the specimen could be finished to a roughness of 0.5 μm. It is shown that the spindle speed, burnishing force, burnishing feed and number of passes have the most significant effect on both surface microhardness and surface roughness and there are many interactions between these parameters. The maximum residual stress changes from tensile to compressive with an increase in burnishing force from 5 to 25 kgf. With a further increase in burnishing force from 25 to 45 kgf, the maximum residual stress increases in compression.     

一车垃圾的新能源之旅

自1985年深圳建设了第一个垃圾焚烧发电厂以来，国家“十一五”规划拟建和在建的垃圾焚烧发电厂有近60座。中国投资咨询网产业研究中心发布的《2009-2012年中国垃圾发电行业投资分析及前景预测报告》中称：垃圾焚烧发电厂目前已吸引国内大批民间资本及国际资本参与其中，预计2010年全国垃圾发电行业年投资额将高达800亿元；到2020年，全国将新增垃圾发电装机容量约330万千瓦。     

铜合金过滤技术的探讨

本文对铜合金过滤技术及过滤机理进行了分析和探讨,结果表明,各种形式的过滤器都可以去除铜合金熔体中的夹杂物及气体,从而减少疏松和气孔,改变金相组织,使晶粒细化,提高了铜合金铸件的机械性能和气密性;研究发现,对铸造过滤来说,由于熔体中夹杂物含量一般很少,不可能产生滤饼过滤机制,机械拦截、深吸附过滤和过滤元件的筛分作用及促使横浇道充满流动是捕获夹杂的主要机制。     

Investigation into laser shock processing

Laser shock processing is a good candidate for surface industry due to its rapid processing, localized ablation, and precision of operation. In the current study, laser shock processing of steel was considered. The numerical solutions for temperature rise and recoil pressure development across the interface of the ablating front and solid are presented. The propagation of elastic-plastic waves in the solid due to recoil pressure loading at the surface is analyzed and numerical solution for the wave propagation was obtained. An experiment was conducted to ablate the steel surfaces for shock processing. Scanning electron microscopy was carried out to examine the ablated surfaces shock processing while transmission electron microscopy was conducted to obtain dislocation densities after the shock processing. It was found that surface hardness of the workpiece increased in the order of 1.8 times of the base material hardness, and the dislocation was the main source of the shock hardening in the region affected by laser shock processing.