熔模铸造液态压注模料初探

近来国外在熔模铸造中越来越多地采用了液态模料。早在1969年苏联《》便曾载文指出,如用糊状压注模料时,蜡模表面光洁度最高可达6,铸件为5。如用液态压注模料,蜡模光洁度可达9以上,铸件可达7以上。 一、液态压注模料的成分、显微组织和性能 对模料显微组织的研究表明:研制液态压注模料的基本指导思想应是,以某种非晶质组元为溶剂,于熔融状态溶入一种或数种晶质组元,形成均质熔体。当冷却时,因溶解度降低,晶质组元析出,模料也随之凝固。所得模料的显微组织为非晶相的基体中     

橡胶衬套压注模的设计与制造

分析了橡胶衬套零件的结构及工艺要求，介绍了橡胶衬套压注模的设计特点及制造工艺。     

石膏型熔模铸造用模料

模料是石膏型熔模铸造工艺的主要技术关键之一。本文从控制模料的显微结构出发,研究出以非晶态玻璃相为基底的共晶型液态模料——48~#和48T~#(含有固体填料)。该两种模料的压注温度和脱蜡温度低,液态粘度小,收缩率小,热稳定性高,强度高,表面硬度高。经一年多的生产考验表明:48~#和48T~#模料满足了石膏型熔模铸造的要求,它适用于制造大型、薄壁、复杂的蜡模,也可用于型壳熔模铸造工艺之中。     

制模工艺参数及计算机控制--国外精铸技术进展述评(3)

介绍国外先进的压蜡机对模料温度、压型温度、注蜡压力以及模料流速等工艺参数的控制技术.为准确控制模料温度应将温度传感器直接插入模料中;而控制压型型腔温度的最好办法是将压型与压板隔开,将热电偶安放在压型靠近型腔表面的位置.注蜡压力和模料流速应单独独立控制,而充型压力和压实压力也须分别加以控制.介绍了模料压注过程的计算机程序控制和计算机实时控制技术.     

压注模具质量无损检测

随着汽车和摩托车制造工业迅速发展 ,两车上塑料件运用得越来越多。一辆豪华高档摩托车覆盖件的表面粗糙度要求是很高的 ,涂装后能使表面光亮照人。覆盖件通常是塑料热压注而成型的 ,它的粗糙度质量好坏与压注模的粗糙度质量有很大关系。一副塑料压注模具 ,材料为 SKD4,合计人民币 1 1 0万元 ,用户单位一开始启用 ,压注出来的覆盖件不合格 ,供方多次修模仍不合格。不合格的原因是覆盖件的表面粗糙度达不到技术要求。经质量分析 ,下模具弧腔面有小凹坑和发纹 ,多次抛光处理 ,粗糙度质量还是不合格。后来经过磁粉探伤 ,发现下模具弧腔面有发…     

自动注料粉末冶金湿压磁场成型模设计

介绍了自动注料粉末冶金湿压成型原理以及自动注料湿压成型模具的设计要点。     

熔模铸造用机械自动压蜡机

设计制造了一种熔模铸造专用气压式机械自动压蜡机,该压蜡机可批量生产小型低温蜡模,在正常工作期间一般不需人工操作,蜡模质量稳定,改善了生产环境,降低了劳动强度.简要介绍了该压蜡机的结构和工作原理.     

橡胶缓冲件双层压注模设计

从产品设计、模具结构和硫化工艺等方面介绍了一种新型橡胶双层压注模的设计。     

注蜡工艺与模料流变性能的关系

利用毛细管流变仪,在对3－3－3－1模料流变性能测试的基础上,根据其流变曲线,分析了如何制定注蜡工艺,最佳匹配注蜡口,模料温度,注蜡压力,并在生产中进行了验证。     

海外文献速报

20 0 40 5 0 1　PatrickManning .降低制模成本的途径 .Incast ,2 0 0 4( 3 ) :2 2～ 2 3着重讨论了如何降低模样蜡和浇道蜡的成本 ,指出可以尝试用回收 再生蜡作冷蜡块和蜡模 ,如果全部使用新蜡的话 ,模料成本往往要占原材料成本的 5 0 %～ 70 %。浇道蜡一般使用回收蜡 ,但回收 再生蜡毕竟不是新蜡 ,它肯定不如新蜡的性能稳定。除使用回收 再生蜡制作蜡模和浇道之外 ,以下途径也有利于降低成本 :①采用膏状蜡比液态蜡压注有利于获得健全的蜡模 ,更缩短制模周期 ,有利于降低制模成本。②使用一种模料来制作蜡模和浇道可减少库存 ,并提…     

乙基纤维素和聚酰胺蜡在晶硅太阳电池电极材料中的应用

通过分析乙基纤维素和聚酰胺蜡在不同溶剂和载体中的粘度及触变性能的作用规律,以研究其对太阳电池正银浆料的丝印特性和电池电极形貌、致密度及电学性能等的关系。发现乙基纤维素和聚酰胺蜡在溶剂中对溶液的粘度分别起到了不同的作用,从而影响着正银浆料的触变和流变性能。其中,乙基纤维素在溶液中的主要作用是提高浆料的整体粘度,而聚酰胺蜡在溶液中主要起着增强浆料剪切变稀的能力。由于浆料的丝印特性主要是通过调节浆料的触变性能来优化的。因此,乙基纤维素和聚酰胺蜡在浆料中的比例对浆料的丝印特性起着十分关键的作用。通过对比乙基纤维素和聚酰胺蜡在浆料中的不同比例对其触变性能及对电池正面电极形貌、致密度和电阻率的影响。结果表明,当乙基纤维素与聚酰胺蜡在浆料中的比例为1:5时,电池栅线电极的高宽比达到最大值,同时栅线电极的线电阻也达到最小值,因此正银浆料达到一个较好的印刷性能。     

NUMERICAL SIMULATION OF FEEDSTOCK MELT FILLING IN A CYLINDRICAL CAVITY WITH SOLIDIFICATION IN POWDER INJECTION MOLDING

ＩＮＴＲＯＤＵＣＴＩＯＮＰｏｗｄｅｒｉｎｊｅｃｔｉｏｎｍｏｌｄｉｎｇ（ＰＩＭ）ｉｓａｐｒｏｃｅｓｉｎｇｒｏｕｔｅｆｏｒｆａｂｒｉｃａｔｉｎｇｍｅｔａｌｏｒｃｅｒａｍｉｃｃｏｍｐｏｎｅｎｔｓｗｉｔｈｃｏｍｐｌｅｘｓｈａｐｅａｎｄｈｉｇｈｐｅｒｆｏｒ?..     

Thermo-physical characterization of binder and feedstock for single and multiphase flow of PIM 316L feedstock

A thorough knowledge of the material properties of the feedstock and binder system is essential for successful powder injection moulding (PIM) as well as for numerical simulation. In view of the above, characterization of a developed binder system and feedstock has been reported in this paper for processing of 316L stainless steel powder through PIM route. The binder system consists of paraffin wax, stearic acid and low-density polyethylene. The feedstock comprises of 316L stainless steel powder and the above binder system. The thermal, physical and rheological characteristics of the binder system and feedstock have been investigated separately along with binder removal technique from the injection-moulded green compact. The thermal characterization revealed the semi-crystalline nature having distinct melting and solidification range for both the binder and feedstock. Data from DSC and TGA show that injection of the feedstock should be carried out above 102 °C (i.e. the upper melting temperature) but below 154 °C as beyond which the binder components paraffin wax and stearic acid start degrading and mould temperature should be below 57 °C. The binder and feedstock are found as shear-thinning fluid as viscosity decreases with the increase in shear strain rate and temperature. However, the viscosity of the binder is more sensitive to shear strain rate and temperature compared to that of the feedstock.     

Electromagnetic characterization of grouting materials of bridge post tensioned ducts for NDT using capacitive probe

The use of a capacitive probe as a non-destructive investigative technique for controlling the post tensioned ducts of bridges has gained increasing acceptance in France since several years. A field campaign measurement made in 2006 has shown the performance of the capacitive probe developed by the IFSTTAR. Nevertheless, some results are not understood, and in particular the behaviour of the probe when cement exudation product are present in the duct. Without an accurate knowledge of the electromagnetic properties of those products it is impossible to quantitatively assess the results of our capacitive probe. This paper reports the development of a coaxial transmission line feature. It was designed to allow the evaluation of a large type of material (liquid, paste or granular) over a large frequency range (50 MHz–4 GHz at maximum). A calibration scheme developed before at the Fresnel Institute was used. Using a two port S parameter instrument, the complex permittivity and magnetic permeability were evaluated by frequency domain measurement. The electromagnetic characterization of cement paste, cement exudation products and injection wax has brought us some key results in the interpretation of the capacitive probe signal. The results of this characterization were then used in a 3D semi analytical modelling of the problem. The studies of configurations with exudation products are presented and compared to experimental results obtained with our capacitive probe on laboratory duct.     

半固态金属铸造的新进展——注射成形

介绍了半固态金属铸造的最新发展趋势-注射成形,它将塑料的注射成形原理应用于半固态金属铸造中,集半固态金属浆料的制备、输送、成形等过程于一体,较好地解决了半固态金属浆料的保存输送和成形控制等问题。通过简述几种半固态金属注射成形工艺方法的原理及特点,试图展示兰固态金属铸造技术工程应用的关键及发展方向。     

半固态金属铸造的新进展——注射成形

介绍了半固态金属铸造的最新发展趋势———注射成形 ,它将塑料的注射成形原理应用于半固态金属铸造中 ,集半固态金属浆料的制备、输送、成形等过程于一体 ,较好地解决了半固态金属浆料的保存输送和成形控制等问题。通过简述几种半固态金属注射成形工艺方法的原理及特点 ,试图展示半固态金属铸造技术工程应用的关键及发展方向     

Finite element analysis of liquid ejection in continuously cast slab by sequential forging

Since segregation occurs at the central part of the continuously cast slab, it is desirable to eject the liquid in the centre during solidification by sequential forging. The deformation behaviour of continuously cast slab during forging is simulated by the finite element method. A model experiment using paraffin wax is also carried out to compare with the theoretical result. The model experiment shows that the liquid may be trapped in the slab during the successive forging process, depending on the striking interval, even when the reduction in thickness is larger than the initial thickness of the liquid part. The calculated profile of the interface between the solid and the liquid parts is wavier and the solid part is deformed more as the striking interval increases. The calculated maximum thickness of the liquid part after forging agrees qualitatively well with the experimental one. The predicted maximum striking interval without liquid trapping in the forging process agrees well with the experimental one.     

熔模铸造常用压蜡机的特点及选型

压蜡机是熔模铸造的关键设备，压蜡机选型时应充分了解各种型号压蜡机的特点，并根据模料的种类，精铸产品的品质要求、材质、批量和铸件大小等进行合理选择。     

高分辨率丝印低温银浆的制备

研究了有机载体中溶剂、树脂、触变剂和银粉含量对低温银浆印刷分辨率的影响。结果表明,不同载体的树脂、溶剂和触变剂对银浆的印刷性有很大影响,银粉的含量对浆料的电性能直接相关。优选的以二价酸酯(38.5%)为溶剂、饱和聚酯(10%)为载体、聚酰胺蜡(0.5%)为触变剂、片状银粉(51%)制备出的低温银浆印刷分辨率高。浆料性能如下：粘度为36.5 Pa·s、触变指数为26.8,在PET、PC、ITO等基材上,用于印刷线宽为100μm时,在x轴和y轴方向扩边率均小于10%,方阻12 m?/□,满足高分辨率精密印刷的要求。     

钢液RH精炼过程中的喷粉脱硫

简要介绍了钢液RH喷粉脱硫的有关方法,分析和综述了相应的粉剂、传质研究及动力学模型等。指出：以冶金反应工程学的观点、原理和方法深入研究钢液RH精炼喷粉脱硫过程无疑具有理论意义和实践价值。