A principal component analysis-cerebellar model articulation controller （PCA-CMAC） model is proposed for machine performance degradation assessment.PCA is used to feature selection,which eliminates the redundant inf...A principal component analysis-cerebellar model articulation controller （PCA-CMAC） model is proposed for machine performance degradation assessment.PCA is used to feature selection,which eliminates the redundant information among the features from the sensor signals and reduces the dimension of the input to CMAC.CMAC is used to assess degradation states quantitatively based on its local generalization ability.The implementation of the model is presented and the model is applied in a drilling machine to assess the states of the cutting tool. The results show that the model can assess the wear states quantitatively based on the normal state of the cutting tool.The influence of the quantization parameter g and the generalization parameter r in the CMAC model on the assessment results is analyzed.If g is larger,the generalization ability is better,but the difference of degradation states is not obvious.If r is smaller,the different states are distinct,but memory requirements for storing the weights are larger.The principle for selecting two parameters is that the memory storing the weights should be small while the degradation states should be easily distinguished.展开更多
In this paper, the principle of multi-point forming (MPF) technique is presented. One of the most serious defects, wrinkling, during the multi-point forming process of a shallow rectangle cup is discussed by means of ...In this paper, the principle of multi-point forming (MPF) technique is presented. One of the most serious defects, wrinkling, during the multi-point forming process of a shallow rectangle cup is discussed by means of numerical simulation on the shallow rectangle cup forming process. The effects of thickness, material of sheet metal and the pressure of the blank holder are investigated. Based on the simulation results, the reasons and control methods of wrinkling are pointed out. Moreover, the experiment on the multi-point die forming of the shallow rectangle cup by the MPF machine is done to validate the efficiency of the numerical simulation, and the result proves that the application of an elastic cushion in the forming can restrain wrinkling efficiently.展开更多
针对大同煤矿集团公司中央机厂近年来工作阻力大于10 000 k N或支护高度大于4 m液压支架的大批量制造,在生产过程中,从结构件的原材料选用、下料要求、组点成型、焊接、机加工、表面抛丸除锈、以及结构件的涂装工艺要求等各个工序制定...针对大同煤矿集团公司中央机厂近年来工作阻力大于10 000 k N或支护高度大于4 m液压支架的大批量制造,在生产过程中,从结构件的原材料选用、下料要求、组点成型、焊接、机加工、表面抛丸除锈、以及结构件的涂装工艺要求等各个工序制定并严格执行制造工艺规范,达到了预期效果。展开更多
Pitting behavior of thixoformed A356 alloy, with different reheating temperatures, was evaluated. Linear sweep voltammetric tests were used to study the pitting behavior of thixoformed, rheocast and gravity-cast A356 ...Pitting behavior of thixoformed A356 alloy, with different reheating temperatures, was evaluated. Linear sweep voltammetric tests were used to study the pitting behavior of thixoformed, rheocast and gravity-cast A356 alloy in a 3.5% NaCl solution. A simulation method was also used in order to identify local galvanic corrosion current density between local galvanic couples. The results obtained show that the resistance to pitting corrosion of the thixoformed samples formed at 600 ℃ is higher than that of the samples formed at 610 ℃ as well as rheocast and gravity-cast samples. These results could be explained by morphological aspects of silicon phase as well as the area effect as related to galvanic corrosion between silicon particles and eutectic aluminum phase.展开更多
基金The National Natural Science Foundation of China(No.60443007,50390063).
文摘A principal component analysis-cerebellar model articulation controller （PCA-CMAC） model is proposed for machine performance degradation assessment.PCA is used to feature selection,which eliminates the redundant information among the features from the sensor signals and reduces the dimension of the input to CMAC.CMAC is used to assess degradation states quantitatively based on its local generalization ability.The implementation of the model is presented and the model is applied in a drilling machine to assess the states of the cutting tool. The results show that the model can assess the wear states quantitatively based on the normal state of the cutting tool.The influence of the quantization parameter g and the generalization parameter r in the CMAC model on the assessment results is analyzed.If g is larger,the generalization ability is better,but the difference of degradation states is not obvious.If r is smaller,the different states are distinct,but memory requirements for storing the weights are larger.The principle for selecting two parameters is that the memory storing the weights should be small while the degradation states should be easily distinguished.
文摘In this paper, the principle of multi-point forming (MPF) technique is presented. One of the most serious defects, wrinkling, during the multi-point forming process of a shallow rectangle cup is discussed by means of numerical simulation on the shallow rectangle cup forming process. The effects of thickness, material of sheet metal and the pressure of the blank holder are investigated. Based on the simulation results, the reasons and control methods of wrinkling are pointed out. Moreover, the experiment on the multi-point die forming of the shallow rectangle cup by the MPF machine is done to validate the efficiency of the numerical simulation, and the result proves that the application of an elastic cushion in the forming can restrain wrinkling efficiently.
文摘Pitting behavior of thixoformed A356 alloy, with different reheating temperatures, was evaluated. Linear sweep voltammetric tests were used to study the pitting behavior of thixoformed, rheocast and gravity-cast A356 alloy in a 3.5% NaCl solution. A simulation method was also used in order to identify local galvanic corrosion current density between local galvanic couples. The results obtained show that the resistance to pitting corrosion of the thixoformed samples formed at 600 ℃ is higher than that of the samples formed at 610 ℃ as well as rheocast and gravity-cast samples. These results could be explained by morphological aspects of silicon phase as well as the area effect as related to galvanic corrosion between silicon particles and eutectic aluminum phase.
