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基于CBR和FMEA知识模型的产品保证成本预测方法研究 总被引:1,自引:0,他引:1
为了满足产品设计阶段数据信息少、参数不确定条件下产品保证成本预测的要求,提出了基于CBR和FMEA知识模型的保证成本预测方法,通过事例推理的方法从事例库中检索最相似事例来预测新产品的保证成本.重点研究了基于FMEA知识模型的事例库组织模型和基于模拟退火算法的事例权重优化方法,提高了事例的检索效率和准确度.最后通过一个实例证明了该方法的有效性. 相似文献
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电镦成形是船用气阀预成形的有效方式之一,然而电镦成形过程中工艺参数的互相匹配很重要,工艺参数匹配或是变化规律不当,成形件的形状和晶粒目标就不会很好实现.本文通过研究气阀电镦变形参数对几何形状和晶粒晶界目标的影响规律,探究电镦成形加载规律,形成五种加载模式,从而达到协调控制产品形状与组织,改善气阀电热镦粗成形形状及内部组... 相似文献
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通过深入分析点焊工艺过程,结合基于事例推理的特点,将点焊工艺事例属性划分为两类:事例特征I和事例特征Ⅱ。设计了相似点焊工艺事例的检索策略:在事例特征I的约束下,以事例特征中Ⅱ所包含的材质的热物理性质和板厚作为检索相似事例的依据。应用模糊推理的方法对检索到相应的相似事例库中所含有的工艺知识、规则进行提取、总结,进而指导对新的点焊工艺事例的求解,从而较好的解决了点焊工艺设计中基于事例推理时,难以建立合适的模型对检索到的相似事例进行修正的难点,使点焊工艺参数的智能求解过程更加符合领域专家的思维,过程更加灵活,具有开放性。 相似文献
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提出一种基于火焰形状的氧化铝回转窑火焰图像的检索方法,对回转窑火焰的形状进行深入分析,根据其特点,提出一种描述火焰形状的基准距离函数,通过傅里叶变换得到火焰图像形状的傅里叶描述子。结果表明:该距离函数能较好地描述火焰形状,应用此火焰形状描述子,设计一套火焰图像检索原型机系统。以现场采集的火焰图像作为实验对象,将本研究提出的方法与传统方法和不变矩方法的进行检索实验。结果表明:本研究提出的方法具有较高的检索精度,且明显优于传统方法和不变矩方法。本研究的结果可为回转窑生产控制提供有力支持。 相似文献
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《塑性工程学报》2019,(6)
为描述材料在塑性成形中的复杂硬化行为,提出了一种基于三次贝塞尔曲线的屈服轨迹离散插值型描述方法,以及后继屈服轨迹演化模型。针对Khan A S等采用Al6061-T6511铝合金进行拉伸-扭转复合预加载后,采用10~(-5)量级的屈服应变阈值时,二维应力空间屈服轨迹表现出极其强烈的大小、中心点和形状变化的实验结果,构造了相应的离散插值型屈服轨迹数值模型,通过拟合实验结果得到了各预应变条件下的曲线参数;提出了描述后继屈服轨迹大小、中心点和形状变化的拟合模型以描述材料的各向同性强化、随动强化和畸变强化行为。与采用应力不变量的建模方法相比,这种屈服模型是依据屈服轨迹的几何形状建立的,具有较大的灵活性。 相似文献
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A new straightening method is proposed for the curved shape near both ends of seamless pipe by using a rotary forming process with three rollers. A helical rolling mill with three rollers was used in the experiment. The prebend aluminum seamless pipes were straightened under various working conditions. It was found that the pitch and the nominal reduction in radius can determine an attainable straightening ratio of the product, and there exists a minimum length of rollers to guarantee the selected straightening ratio of the product. The curved shape of pipe specimen can be straightened up to 90% under optimum working conditions. It was also found that there exists a maximum pitch to guarantee a certain straitening ratio of the product, and the axial feed rate can be selected arbitrarily in practice. 相似文献
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Many process parameters have an effect on the sheet metal forming process. A well-designed blank shape causes the material
to flow smoothly, reduces the punch force, and yields a product with a uniform thickness distribution. Therefore, the determination
of an initial blank shape plays the important role of saving time and cost in the sheet metal forming process. For these reasons,
some approaches to estimate the initial blank shape have been implemented.
In this paper, the one-step approach using a finite element inverse method will be introduced to predict the initial blank
shape. The developed program is applied to several sheet metal forming examples for the demonstration of its validity. Moreover,
the usefulness of the developed one-step approach program is investigated as compared with the FAST-3D program, which is a
commercial package that is commonly used. Finally, the verification will be performed by comparing the predicted and experimental
results. 相似文献
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Shichao Ding Paul A. MeehanWilliam J.T. Daniel 《Journal of Materials Processing Technology》2011,211(3):376-381
Millipede forming, a novel sheet metal forming method, has been proposed and developed recently to overcome fundamental limitations in conventional roll forming. For this new method, there are two main aspects: use of an optimal transitional surface and implementation of a method to feed the strip through the transition surface. Achieving the optimal transitional surface involves defining the change of surface shape between a flat strip and a final shaped product conceptualised to the strip's mid-surface, regardless of the strip's thickness.In this paper, one method of implementing a transition surface, Millipede forming, is introduced. A prototype has been built to demonstrate the working principle and can be used to produce some simple profiles, within a short forming length of 200 mm. 相似文献
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矩形盒拉深成形中的几何形状效应 总被引:4,自引:0,他引:4
根据大量矩形盒拉深试验结果,对成形过程中的几何形状效应进行了分析和总结。指出形状参数rc/ω直接决定矩形盒相对拉深比和法兰变形加工度,并与成形极限密切相关。rc/ω小,法兰曲边变形加工度大,变形缓和作用增强。rc/ω大,板坯的几何形状效应增强,适当改变板坯形状和长、短边相对尺寸可提高成形极限。 相似文献
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Asghar Shamsi-Sarband Seyed Jamal Hosseinipour Mohammad Bakhshi-Jooybari Mohsen Shakeri 《Journal of Materials Engineering and Performance》2013,22(12):3601-3611
A combination of sensitivity analysis and finite element simulation has been developed for the preform design in two-stage superplastic forming process. The aim is to present a simple approach to generate an estimate for the preform shape. In this respect, the commercial finite element software ABAQUS/Standard 6.8 was used as a computational tool and sensitivity analysis was used for preform design by minimizing the mean fractional deviation from the target thickness as an objective function. The predicted preform was verified through comparison with experimental results by investigating the deformation of AA5083 sheet at temperature of 500 °C. The effect of the geometric parameters of conical cups on the preform shape was examined. The results showed that the geometric parameters have a significant effect on the preform shape. By increasing the height and the cone angle of the final cup, the depth of the preform in the inner cavity decreases and the dome region is approached to the center of the preform cup. By increasing the corner radius of the final-die, only the height of the dome region decreases. 相似文献
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整体翅片管的劈切—挤压加工 总被引:8,自引:2,他引:6
提出了一种新的本翅片管的机械加工方法,即劈切-挤压加工,实验观察发现,翅片的形成包括切入、挤压和成形3个阶段,实验结果表明,影响翅片形成的主要有刀具几何参数、挤压深度,进给量和劈切-挤压速度;对某一刀具,在选定挤压速度时,一定的挤压深度对应一个极限进人量,一定的进给量对应一个极限挤压深度。选择合理的参数可保证翅片加工的连续性和获得接近最佳形状的翅片。劈切-挤坟加工在普通车床上进行,设备简单易,翅片一次成形,材料利用率高,是一种能降低加工技术,提高生产率的加工方式。 相似文献