稳步发展的压铸技术——第五届中国国际压铸会议论文综述

介绍了“第五届中国国际压铸会议”关于压铸学术交流概况,对压铸生产的发展状况,铝合金压铸、半固态技术的发展,镁合金压铸、半固态技术的发展,计算机模拟技术在压铸中的应用、挤压技术的研究发展和其它方面等6个部分的会议论文进行了评述,并提出了未来压铸行业的工作重点。     

Anti-oxidation mechanism of SiC-B4C-C composites

Mixture of green petroleum coke, B4 C and SiC together with short carbon fiber were employed as starting materials, the mixture was press formed without any binder after grinding, dense and homogeneous binderless SiC-B4 C-C（carbon/ceramic） composites were then obtained after sintering. Composites thus prepared possess excellent anti-oxidation property, that is, mass loss less than IG within the temperature range from 900 to 1 100 ℃ for 10 h. Anti-oxidation mechanism was also discussed from the viewpoint of thermodynamics, excellent anti-oxidation property of materials thus prepared can be discribed to 1） solid SiO2 formed from SiC, which restrains the filtering of oxygen and simultaneously, its volume expansion brought about by the reaction takes roles both walling up the original pores and making the material more compact; 2） liquid B2O3 from the reaction of B4C not only makes the combination with C, B4 C and SiC tighter through forming solid solution, but also effect of reaction SiC（s）＋2CO（g） =SiO2 （s）＋3C（s） is an expansive process, which improves the microstructure of the material.     

Ag-Cu-Ti-(Ti+C)反应-复合钎焊SiC陶瓷和 Ti合金的接头组织

研究用合金化Ag-Cu-Ti粉、Ti粉、C粉组成的混合粉末真空无压钎焊再结晶SiC陶瓷和Ti合金,采用X射线衍射、扫描电镜和能谱仪对接头的组织结构进行了分析.结果表明:在67.6%Ag-26.4%Cu-6%Ti(质量分数)粉末中加入相当于15%～30%TiC(体积分数)的(Ti C)粉末(Ti与C摩尔比为1:1),经920℃,30 min真空钎焊,Ti和C原位合成TiC,形成以TiC晶粒强化的连接良好的复合接头;形成的TiC分布于Ag相、Cu-Ti相中;TiC的形成明显降低了接头的热应力.过量的(Ti C)粉末则导致反应不完全,容易在连接层中产生孔洞,影响接头强度;焊接过程中,Ti由钛合金扩散进入连接层,Cu也有部分从连接层中扩散进入钛合金.     

熔镁铁坩埚对镁液的溶铁污染及防治措施

熔镁铁坩埚在使用过程中会产生铁在镁液中的溶解,造成镁液铁污染和坩埚腐蚀,针对这一问题,分析产生的原因和机理,着重介绍几种防止铁坩埚产生溶铁污染的方法,并进行了评述.     

摩擦片精冲成形实验研究

提出采用精冲工艺进行车辆摩擦片的生产.根据摩擦片的结构特点、加工硬化、应力分布及材料等,讨论了精冲成形和热处理的技术难点,制定了摩擦片的精冲工艺;然后再根据实验过程中获得的齿顶圆、齿根圆及碟形量变化曲线,分析其产生原因并提出了解决成形过程中变形问题的措施,已制造出符合质量要求的摩擦片精冲件.     

椭圆弧数控代码的自动生成方法

提出了一种基于计算机辅助制造的数控加工代码自动生成的方法，着重阐述了该方法针对椭圆弧的数控代码自动生成过程。该方法通过分析加工图形的dxf文件，提取图形的坐标信息，再经过数据拟和，自动生成该图形的数控代码。该方法由VC＋＋6．0实现相应的功能，经实际运行表明，能满足加工精度要求。该方法摆脱了传统数控机床从加工图形到形成数控加工代码时间长且精度不高的缺点，极大她提高了工作效率。     

模糊控制器在气力送丝系统中的应用

在卷烟厂气力送丝系统中，由于管道阻力不断变化引起的输送气流压力波动，采用传统的PID控制方法难以获得满意的效果?因此设计了一种送丝压力模糊控制器，应用结果表明该送丝控制器较好地改善了控制系统的性能和适应能力，满足了生产需要。     

Modeling and Simulation of Heat Transfer in Loaded Continuous Heat Treatment Furnace

HEAT UP processing is the basic step for the workloadin heat treatment for further processing.It is also anenergy-intensive process.Thus,correct prediction ofthe temperature variation and distribution in theworkload is of significance to ensure the final qualityof the parts and to reduce energy consumption and timeas well.There are some studies about the optimizationof heat treating process in continuous furnace.FurnXpert'11is developed to optimize furnace designand operation for many types…     

HA/Ti composite for biomedical application by mechanical milling

In order to overcome the poor mechanical properties of HA and the low bioactivity of Ti,HA/Ti composites with various compositions were prepared by mechanical milling.The effects of milling condition and the composition on the microstructure,the density and the hardness of the composites were studied.The results show that during the ball milling process.Ti particles are refined and the homogeneity of the HA/Ti mixtures is improved;HA will partially decompose due to the existence of Ti and high sintering temperature.The microstructure of HA/Ti composites is highly dependent on the milling condition and the composition.In the microstructure.Ti phase connects to be a continuous network,and HA/Ti mixtures disperse in the network.The longer the milling time,the finer the network will be.The density of HA/T composites decreases with the content of HA increasing and the milling time prolonging,because HA deteriorates the sinterability of Ti.The hardness of HA/Ti composites increases firstly with the content of HA increasing,and then drops when the content of HA exceeds 30%.Addition of HA will strengthen the HA/T composite but will decrease the density of the composite,which accounts for the effect of HA on the hardness of the composites.     

基于选择性激光烧结方法的金属零件快速制造技术研究

主要研究了通过选择性激光烧结高分子原型件制造金属零件的工艺。通过采用真空压差铸造工艺。结合铸造型壳的制造，成功制造出金属零件。对基于SLS技术的精密铸造过程中的精度控制进行了研究分析，并提出了解决办法。