气动微震造型机的特性

一、前言各种造型机在铸造厂中广泛应用,但过去的造型机主要是考虑造型能力,对于防噪音、防震等不太考虑。因此,采用震实机构的造型机在基础不够好时,由于震动往往会造成各种故障。特别是大型震实造型机。

Microstructure and mechanical properties of Mg-Gd-Y-Zr alloy cast by metal mould and lost foam casting

The microstructure and mechanical properties of Mg-10.1Gd-3.74Y-0.25Zr （mass fraction, %） alloy （GW104 alloy） cast by metal mould casting （MMC） and lost foam casting （LFC） were evaluated, respectively. It is revealed that different forming modes do not influence the phase composition of as-cast alloy. In the as-cast specimens, the microstructures are similar and composed of α-Mg solid solution, eutectic compound of α-Mg＋Mg 24 （Gd, Y） 5 and cuboid-shaped Mg 5 （Gd, Y） phase; whereas the average grain size of the alloy produced by metal mould casting is smaller than that by lost foam casting. The eutectic compound of the alloy is completely dissolved after solution treatment at 525 ℃for 6 h, while the Mg 5 （Gd, Y） phase still exists after solution treatment. After peak-ageing, the lost foam cast alloy exhibits the maximum ultimate tensile strength of 285 MPa, and metal mould cast specimen 325 MPa at room temperature, while the tensile yield strengths of them are comparable. It can be concluded that GW104 alloy cast by lost foam casting possesses similar microstructure and evidently lower mechanical strength compared with metal mould cast alloy, due to slow solidification rate and proneness to form shrinkage porosities during lost foam casting process.

Effect of heat treatment on microstructures and mechanical properties of sand-cast Mg-4Y-2Nd-1Gd-0.4Zr magnesium alloy

Influence of heat treatment on the microstructures and mechanical properties of sand-cast Mg-4Y-2Nd-1Gd-0.4Zr magnesium alloy was investigated,and the tensile fracture mechanisms of the studied alloys under different conditions were also discussed.The results show that the optimum T4 and T6 heat treatment conditions for the as-cast Mg-4Y-2Nd-1Gd-0.4Zr alloy are 525°C,8 h and（525°C,8 h）＋（225°C,16 h）,respectively,with regard to the microstructure observation,DSC heating curve and mechanical properties.The hardness,yield strength,ultimate tensile strength and elongation of the Mg-4Y-2Nd-1Gd-0.4Zr alloy treated by optimum T6 heat treatment are HV91,180 MPa,297 MPa and 7.4%,respectively.Moreover,the Mg-4Y-2Nd-1Gd-0.4Zr alloys under different heat treatment conditions exhibit different tensile fracture modes.

Effect of Nb addition on microstructure,mechanical properties and castability of β-type Ti-Mo alloys

To develop novel β-type biomedical titanium alloys,a series of Ti-15Mo-xNb alloys（x=0,5,10 and 15,mass fraction in%） were designed and prepared by using vacuum arc melting method.The present study focused on the effect of Nb addition on the microstructure,mechanical properties and castability of Ti-15 Mo alloy.Phase analysis and microstructure observation show that all the alloys consist of single β phase and the equiaxed β grain is refined with increasing Nb content.These β-type Ti-15Mo-xNb alloys exhibit good plasticity and rather low compression elastic modulus（in the range of 18.388-19.365 GPa）.After Nb addition,the compression yield strength of the alloys increases.With increasing Nb content,the micro-hardness of the alloys decreases.The alloys exhibit obvious fibrous strip microstructure after cold compression deformation.The castability test shows that the castability of the alloys after Nb addition decreases and that of the Ti-15 Mo alloy is the highest（92.01%）.

促进均匀性，优化潮模砂处理

粘土与水比例适当，粘土水化均匀，附加物扩散良好，以及松砂充分是配制合格潮模砂的重要因素。

Microstructure and mechanical properties of A356 thixoformed alloys in comparison with gravity cast ones using new criterion

The effect of thixoforming process on morphologies of silicon particles that affect fracture mode of A356 alloy was investigated.Microstructure and fracture surfaces of thixoformed samples were investigated by image analyzing technique and scanning electron microscopy.A new combination parameter, called silicon density ratio (SDR) index, was introduced.SDR index approximates the collective effects of morphological characteristics of silicon particles on microstructure transparency of alloy in crossing the dislocation.It is suggested that samples with lower SDR index have superior mechanical properties, especially elongation, and consequently intergranular fracture mode.On the contrary, samples with higher SDR index have inferior mechanical properties and fracture path tends to propagate along the cell boundaries leading to transgranular fracture.

Proposal of a Conceptual Model to Analyse the Influence of LARG Practices on Manufacturing Supply Chain Performance

The main objective of this paper is to propose a conceptual model about the influence of lean, agile, resilient, and green （LARG） practices on supply chain operational, economic and environmental performance. This model is based on the literature review about the four supply chain management paradigms and also performance measurement systems. This paper contributes to the literature by introducing a new model to improve the leanness, agility, resilience, and greenness of manufacturing supply chains. Among the suggested LARG practices, the ones influencing more the supply chain performance are the just in time and also the supplier relationships. Also the supply chain performance measures with more LARG practices influencing them are the inventory levels and the time, that is, the supply chain＇s operational performance is the most affected by the simultaneous paradigms deployment in the supply chain.

Modeling Impact of ROADM Intra-Node Add/Drop Contention on a Single Node Lightpath Blocking Performance

We propose an analytical model to evaluate the lightpath blocking performance for a single ROADM node with intra-node add/drop contention,in which the number of lightpaths that can be added/dropped with the same wavelength is limited by the add/drop contention factor.Different models of traffic load per nodal degree are considered to validate the effectiveness of the analytical model.The simulation results show that the proposed analytical model is effective in predicting the performance for different values of add/drop contention factor C and for variable offered loads at the node.The add/drop contention factor shows an important impact on the lightpath blocking performance and properly raising the contention factor can significantly improve the lightpath blocking performance.When the add/drop contention factor C exceeds a certain level,the performance of a ROADM with intra-node contention is close to that of a contentionless ROADM.

Analysis of Do D inkjet printhead performance for printable electronics fabrication using dynamic lumped element modeling and swarm intelligence based optimal prediction

The major challenge in printable electronics fabrication is to effectively and accurately control a drop-on-demand(Do D) inkjet printhead for high printing quality. In this work, an optimal prediction model, constructed with the lumped element modeling(LEM) and the artificial bee colony(ABC) algorithm, was proposed to efficiently predict the combination of waveform parameters for obtaining the desired droplet properties. For acquiring higher simulation accuracy, a modified dynamic lumped element model(DLEM) was proposed with time-varying equivalent circuits, which can characterize the nonlinear behaviors of piezoelectric printhead. The proposed method was then applied to investigate the influences of various waveform parameters on droplet volume and velocity of nano-silver ink, and to predict the printing quality using nano-silver ink. Experimental results show that, compared with two-dimension manual search, the proposed optimal prediction model perform efficiently and accurately in searching the appropriate combination of waveform parameters for printable electronics fabrication.

The step-by-step CFD design method of pressure-compensating emitter

In order to improve the design and research and development (R & D) efficiency of the pressure- compensating drip irrigation emitter,a step-by-step computational fluid dynamics (CFD) design method was proposed based on CFD theory combined with the finite element method. By analyzing its hydraulic performance through the step-by-step CFD method,the prediction pressure-flow curve(p-Q curve) of the pressure-compensating emitter was obtained. Then the test samples were fabricated using rapid prototype and manufacturing(RP & M) technology. The emitters' hydraulic performance experiment was carried out and the experimental p-Q curve was obtained. The step-by-step CFD design method was verified by comparing the experimental p-Q curve with the prediction values,which showed that the prediction values met the experimental results well within the normal range of the emitter's working pressure. On this basis,the effect of the emitter structure on its pressure-compensating performance was studied,which showed that the height of the pressure-compensating region had significant effects on the emitter's pressure-compensating performance. Series products of the pressure-compensating emitter could be designed by changing the region's height.

Geometry effect on mechanical properties of woven fabric composites

The effects of geometry on mechanical properties in woven fabric composites were explored. Two types of composites, including one-layered and two-layered composites, were designed and studied. For one-layered composites, inter-strand gap effects on the mechanical properties were studied, while three cases of geometries with inter-strand gaps in two-layered composites were evaluated. A woven fiber micromechanics analytical model called MESOTEX was employed for theoretical simulation. The predicted results show that the inter-strand gap and simple variation of the strand positions in a repeating unit cell significantly affect the mechanical properties of woven fabric composites.

浅析面料的服用性能在服装设计中的重要性

服装面料行业正朝着高科技创新化的方向发展,以"人性化"为主题的设计思想被广泛应用,新型服装面料被大量开发,舒适、环保、低碳、健康变为首要因素,这也就是无形中大大的提高了服装面料的服用性能。而在服装设计中服装设计师通晓各种面料的服用性能及优势、劣势,以便在今后的服装设计与创作中可以灵活的运用,发挥出面料的最大优势与特性,创作出更多优秀的作品。

铸铁的湿型砂中可否不加煤粉

铸铁件湿型砂中的煤粉具有显著的抗粘砂和使表面光洁效果。煤粉的优点是价格低廉，供应充分易得，应用灵活方便，因而在生产中广泛应用。但是，煤粉还有多种缺点：肮脏，恶化劳动条件和污染环境，车间粉尘中煤粉残留物约占50％。浇注时排放出大量挥发性气体不利于身体健康；落砂后形成的灰分和焦炭残留在型砂中，需要加入更多的水分和膨润土才能保持合适的强度和韧性等造型性能；有的煤粉还可能引起自燃。为了防止污染环境、改善劳动条件，

龙蒂花

第一次看到龙蒂花,是在东京NEW CRAFT株式会社的展示厅里。一束一束用龙蒂花组成的新娘捧花娇艳欲滴地从天花板沿着墙壁象瀑布似地流泻下来。身临其境,颇生飘飘欲仙之感。 龙蒂花艳而不俗,虽假却真,特别是那份亮丽、爽洁实在使人难以不迷恋于她。