The ferrite decarburization behavior of 60Si2MnA spring steel wires for automotive suspensions, including the forming condition and the influence of heating time and cooling rate after hot rolling, was investigated co...The ferrite decarburization behavior of 60Si2MnA spring steel wires for automotive suspensions, including the forming condition and the influence of heating time and cooling rate after hot rolling, was investigated comprehensively. Also, a control strategy during the reheating process and cooling process after rolling was put forward to protect against ferrite decarburization. The results show that ferrite decarburization, which has the strong temperature dependence due to phase transformation, is produced between 675 and 875°C. The maximum depth is found at 750°C. Heating time and cooling rate after rolling have an important influence on decarburization. Reasonable preheating temperature in the billet reheating process and austenitizing temperature in the heat-treatment process are suggested to protect against ferrite decarburization.展开更多
In order to control the composition,morphology and size distribution of oxide inclusions in spring steel,the relationship between the content or activity of aluminum and calcium in molten steel and compositions of oxi...In order to control the composition,morphology and size distribution of oxide inclusions in spring steel,the relationship between the content or activity of aluminum and calcium in molten steel and compositions of oxide inclusion precipitated at different temperatures was determined based on thermodynamic equilibrium for spring steel 60Si2 MnA,and has been verified by practice.The size distribution of non-metallic inclusions electrolytically extracted from specimens of hot rolled spring steel was determined by image analyzer.The results show that there are a great deal of large inclusions in spring steel produced by the conventional process,and the quantity and the size of large inclusions in spring steel produced by new process are largely reduced.As a result,the fatigue properties of the spring steel produced by new process are highly improved,and the ratio ofσ-1/σbis raised from 0.451 to 0.468.展开更多
Increased variability in rainfall events and high production input costs are driving agricultural producers to consider subsurface water management in the flat Red River of the North Valley in Eastern North Dakota and...Increased variability in rainfall events and high production input costs are driving agricultural producers to consider subsurface water management in the flat Red River of the North Valley in Eastern North Dakota and Northwestern Minnesota, USA. Subsurface tile incorporated with water table control structures was utilized from 2009 to 2011 to investigate the response of hard red spring wheat (HRSW) (Triticum aestivum L. emend. Thell.) for yield, disease, and other agronomic characteristics to soil water management. A factorial arrangement of four cultivars, two seed treatments, and two foliar fungicide treatments in a split-plot design with closed and open tile as whole-plots was used. Mean wheat yields averaged across years were not significantly different with closed or open tile treatments. There existed an optimum management practice where plant useable water was not freely drained and analyzing the data with the optimum water management for each year found the optimum water table managed treatment yielded higher with 3812 kg ha-1 compared with limited water table management with 3679 kg ha-1. In 2011, the cultivars Faller and Howard were taller, and Traverse had lower root disease severity. In 2010 and 2011, Howard and Traverse had more leaf disease with open tile compared with closed tile. Across years, there was no difference in root disease, stand, number of spikes, crop height, or yield response to appli-cation of seed treatments with open or closed tile. In 2010, there was a 3.7% yield advantage with application of seed treatment on open tile. Across years, there was no yield response to application of foliar fungicides;however, wheat yield with foliar fungicide was 5% higher than without application in 2010. Producers should be using water table control and disease management to maximize HRSW yield. Further research should investigate water table management throughout the season based on weather conditions.展开更多
An active device using electromagnetic forces was constructed and examined for the purpose of minimizing the resonance in air mounts of clean rooms. The air mounts are vulnerable to low-frequency resonance due to heav...An active device using electromagnetic forces was constructed and examined for the purpose of minimizing the resonance in air mounts of clean rooms. The air mounts are vulnerable to low-frequency resonance due to heavy weight and low stiffness. A hybrid structure of the active device, composed of pneumatic and electromagnetic parts, was developed and tested. The pneumatic parts in the device support heavy weights under the air mounts, and the electromagnetic parts reduce the resonance. The electromagnetic parts are composed of dual stators and an armature, which surround the pneumatic parts. The resonance can decrease when electromagnetic forces are generated in the gaps between the stators and the armature. Four active devices were installed under a 3-ton surface plate for a vibration test apparatus. The vibration was detected by eddy-current sensors. Discrete P Control logic was based on displacement, and embedded in a C6713 DSP. The results from impact tests show that the peak magnitude in the resonance frequency can be reduced to –10 dB.展开更多
The paper aims to analyze the impacts of punch damper stiffness on equipment base and vibration, andintroduce the development and application of a disc spring damper featured hard-soft-hard variable stiffness. Adamper...The paper aims to analyze the impacts of punch damper stiffness on equipment base and vibration, andintroduce the development and application of a disc spring damper featured hard-soft-hard variable stiffness. Adamper has four damping columns with C-type disc springs whose laminates plate number gradually increases setby set. Compared with its counterparts, this kind of dampers has the advantages of high energy absorption andvibration damping effect, which not only can effectively reduce the vibration of the foundation of punch press,but also prevents the vibration range from increasing. Also, this kind of dampers is of low cost and convenient touse.展开更多
文摘The ferrite decarburization behavior of 60Si2MnA spring steel wires for automotive suspensions, including the forming condition and the influence of heating time and cooling rate after hot rolling, was investigated comprehensively. Also, a control strategy during the reheating process and cooling process after rolling was put forward to protect against ferrite decarburization. The results show that ferrite decarburization, which has the strong temperature dependence due to phase transformation, is produced between 675 and 875°C. The maximum depth is found at 750°C. Heating time and cooling rate after rolling have an important influence on decarburization. Reasonable preheating temperature in the billet reheating process and austenitizing temperature in the heat-treatment process are suggested to protect against ferrite decarburization.
基金Item Sponsored by National Natural Science Foundation of China(59874023)
文摘In order to control the composition,morphology and size distribution of oxide inclusions in spring steel,the relationship between the content or activity of aluminum and calcium in molten steel and compositions of oxide inclusion precipitated at different temperatures was determined based on thermodynamic equilibrium for spring steel 60Si2 MnA,and has been verified by practice.The size distribution of non-metallic inclusions electrolytically extracted from specimens of hot rolled spring steel was determined by image analyzer.The results show that there are a great deal of large inclusions in spring steel produced by the conventional process,and the quantity and the size of large inclusions in spring steel produced by new process are largely reduced.As a result,the fatigue properties of the spring steel produced by new process are highly improved,and the ratio ofσ-1/σbis raised from 0.451 to 0.468.
文摘Increased variability in rainfall events and high production input costs are driving agricultural producers to consider subsurface water management in the flat Red River of the North Valley in Eastern North Dakota and Northwestern Minnesota, USA. Subsurface tile incorporated with water table control structures was utilized from 2009 to 2011 to investigate the response of hard red spring wheat (HRSW) (Triticum aestivum L. emend. Thell.) for yield, disease, and other agronomic characteristics to soil water management. A factorial arrangement of four cultivars, two seed treatments, and two foliar fungicide treatments in a split-plot design with closed and open tile as whole-plots was used. Mean wheat yields averaged across years were not significantly different with closed or open tile treatments. There existed an optimum management practice where plant useable water was not freely drained and analyzing the data with the optimum water management for each year found the optimum water table managed treatment yielded higher with 3812 kg ha-1 compared with limited water table management with 3679 kg ha-1. In 2011, the cultivars Faller and Howard were taller, and Traverse had lower root disease severity. In 2010 and 2011, Howard and Traverse had more leaf disease with open tile compared with closed tile. Across years, there was no difference in root disease, stand, number of spikes, crop height, or yield response to appli-cation of seed treatments with open or closed tile. In 2010, there was a 3.7% yield advantage with application of seed treatment on open tile. Across years, there was no yield response to application of foliar fungicides;however, wheat yield with foliar fungicide was 5% higher than without application in 2010. Producers should be using water table control and disease management to maximize HRSW yield. Further research should investigate water table management throughout the season based on weather conditions.
文摘An active device using electromagnetic forces was constructed and examined for the purpose of minimizing the resonance in air mounts of clean rooms. The air mounts are vulnerable to low-frequency resonance due to heavy weight and low stiffness. A hybrid structure of the active device, composed of pneumatic and electromagnetic parts, was developed and tested. The pneumatic parts in the device support heavy weights under the air mounts, and the electromagnetic parts reduce the resonance. The electromagnetic parts are composed of dual stators and an armature, which surround the pneumatic parts. The resonance can decrease when electromagnetic forces are generated in the gaps between the stators and the armature. Four active devices were installed under a 3-ton surface plate for a vibration test apparatus. The vibration was detected by eddy-current sensors. Discrete P Control logic was based on displacement, and embedded in a C6713 DSP. The results from impact tests show that the peak magnitude in the resonance frequency can be reduced to –10 dB.
基金supported by the Scientific Research Project of Jieyang Vocational and Technical College(2017JYCKY01)the Innovation and Development Special Fund Project of Jieyang(2017xm014)
文摘The paper aims to analyze the impacts of punch damper stiffness on equipment base and vibration, andintroduce the development and application of a disc spring damper featured hard-soft-hard variable stiffness. Adamper has four damping columns with C-type disc springs whose laminates plate number gradually increases setby set. Compared with its counterparts, this kind of dampers has the advantages of high energy absorption andvibration damping effect, which not only can effectively reduce the vibration of the foundation of punch press,but also prevents the vibration range from increasing. Also, this kind of dampers is of low cost and convenient touse.
