Laser heat treatment is considered to be one of best-performing manufacturing processes used currently due to its flexibility and its ability to develop parts with complex geometries. In fact, this process is able to ...Laser heat treatment is considered to be one of best-performing manufacturing processes used currently due to its flexibility and its ability to develop parts with complex geometries. In fact, this process is able to produce reliable parts with hard, thin martensite and compressive residual stresses. This paper explores the heat treatment applied to 4340 cylindrical parts heated using a Nd: Yag 3 kW laser source. In this case, the hardness profile is correlated to process parameters such as the laser source power, the beam scanning speed and the revolution speed of the part during heating. Based on preliminary tests stipulating that each parameter is varied alone within a specific range, a systematic design of final tests is performed using Taguchi matrix. The obtained results are analyzed using ANOVA method to extract the effects, the contributions and the interaction between the factors. The results are then exploited to study the sensitivity of the case depth according the variation of the process parameters. The developed model exhibits good potential for converging towards a robust model able to predict the hardness curve and to generalize it for other dimensions of cylindrical parts.展开更多
针对连续性工业生产特点,重点关注类别不平衡造成的不合格样本召回率低问题。为了从高维数据提取有效特征,结合one class F-score和最小冗余最大相关性在特征提取方面的优势,有效降低特征维度并提取有价值特征;利用Wasserstein生成对抗...针对连续性工业生产特点,重点关注类别不平衡造成的不合格样本召回率低问题。为了从高维数据提取有效特征,结合one class F-score和最小冗余最大相关性在特征提取方面的优势,有效降低特征维度并提取有价值特征;利用Wasserstein生成对抗网络(WGAN)方法扩增不合格样本数量;通过类别权重优化Focal Loss函数以提高困难样本识别率;通过轻量级梯度提升机算法结合阈值移动策略,构建基于WGAN数据增强和难例挖掘技术的质量预测模型(WGAN_Focal Loss_LGB(TM))。将所提模型应用于开源SECOM数据集,验证了所提方法的有效性。展开更多
针对电火花修整超硬砂轮过程中选择合适放电参数困难的问题,引入基于实例的推理(CBR)和基于规则的推理(RBR)相结合的推理技术,确定了电火花修整超硬砂轮实例表示和实例相似度计算及权值分配的方法,阐述了电火花修整放电规准和规则表示,...针对电火花修整超硬砂轮过程中选择合适放电参数困难的问题,引入基于实例的推理(CBR)和基于规则的推理(RBR)相结合的推理技术,确定了电火花修整超硬砂轮实例表示和实例相似度计算及权值分配的方法,阐述了电火花修整放电规准和规则表示,并以Visual Basic 6.0为开发工具,以SQL Server 2005为底层数据库支持软件,开发了电火花修整超硬砂轮专家系统。将该系统应用于青铜结合剂CBN砂轮NBC160M100的放电参数选择中,实验结果表明,基于CBR-RBR的推理技术可行有效。展开更多
文摘Laser heat treatment is considered to be one of best-performing manufacturing processes used currently due to its flexibility and its ability to develop parts with complex geometries. In fact, this process is able to produce reliable parts with hard, thin martensite and compressive residual stresses. This paper explores the heat treatment applied to 4340 cylindrical parts heated using a Nd: Yag 3 kW laser source. In this case, the hardness profile is correlated to process parameters such as the laser source power, the beam scanning speed and the revolution speed of the part during heating. Based on preliminary tests stipulating that each parameter is varied alone within a specific range, a systematic design of final tests is performed using Taguchi matrix. The obtained results are analyzed using ANOVA method to extract the effects, the contributions and the interaction between the factors. The results are then exploited to study the sensitivity of the case depth according the variation of the process parameters. The developed model exhibits good potential for converging towards a robust model able to predict the hardness curve and to generalize it for other dimensions of cylindrical parts.
文摘针对连续性工业生产特点,重点关注类别不平衡造成的不合格样本召回率低问题。为了从高维数据提取有效特征,结合one class F-score和最小冗余最大相关性在特征提取方面的优势,有效降低特征维度并提取有价值特征;利用Wasserstein生成对抗网络(WGAN)方法扩增不合格样本数量;通过类别权重优化Focal Loss函数以提高困难样本识别率;通过轻量级梯度提升机算法结合阈值移动策略,构建基于WGAN数据增强和难例挖掘技术的质量预测模型(WGAN_Focal Loss_LGB(TM))。将所提模型应用于开源SECOM数据集,验证了所提方法的有效性。
文摘针对电火花修整超硬砂轮过程中选择合适放电参数困难的问题,引入基于实例的推理(CBR)和基于规则的推理(RBR)相结合的推理技术,确定了电火花修整超硬砂轮实例表示和实例相似度计算及权值分配的方法,阐述了电火花修整放电规准和规则表示,并以Visual Basic 6.0为开发工具,以SQL Server 2005为底层数据库支持软件,开发了电火花修整超硬砂轮专家系统。将该系统应用于青铜结合剂CBN砂轮NBC160M100的放电参数选择中,实验结果表明,基于CBR-RBR的推理技术可行有效。
