Cam profiles play an important part in the performance of cam mechanisms. Syntheses of cam profile designs and dynamics of cam designs are studied at first. Then, a cam profile design optimization model based on the s...Cam profiles play an important part in the performance of cam mechanisms. Syntheses of cam profile designs and dynamics of cam designs are studied at first. Then, a cam profile design optimization model based on the six order classical spline and single DOF(degree of freedom) dynamic model of single-dwell cam mechanisms is developed. And dynamic constraints such as jumps and vibrations of followers are considered. This optimization model, with many advantages such as universalities of applications, conveniences to operations and good performances in improving kinematic and dynamic properties of cam mechanisms, is good except for the discontinuity of jerks at the end knots of cam profiles which will cause vibrations of cam systems. However, the optimization is improved by combining the six order classical spline with general polynomial spline which is the so-called "trade-offs". Finally, improved optimization is proven to have a better performance in designing cam profiles.展开更多
The forming quality of metal bipolar plate(BPP)flow channels in proton exchange membrane fuel cells(PEMFCs)is a key factor affecting battery performance.A flow channel with straight sidewalls and a low thinning rate c...The forming quality of metal bipolar plate(BPP)flow channels in proton exchange membrane fuel cells(PEMFCs)is a key factor affecting battery performance.A flow channel with straight sidewalls and a low thinning rate can enhance battery output.Roll forming,as a new technology for BPP production,offers advantages such as a low thinning rate and high efficiency.However,existing roll curve design methods struggle to accommodate both low thinning rates and straight sidewall angles simultaneously.This study aims to develop flow channels with right-angled sidewalls,which provide benefits such as a low thinning rate,reduced residual stress,and high accuracy.A roller tooth profile was designed to achieve a flow channel with right-angled sidewalls and minimal thinning.Simulations and experiments were conducted to validate the feasibility of this novel design method for the roll forming process.The study investigated the effects of roller tooth parameters on sidewall angle,thinning rate,and residual stress.A multifactor evaluation method was developed to optimize the tip fillet radius and the tooth profile backlash of the roller.The results indicated that the tip fillet radius and the tooth profile backlash were negatively correlated with the sidewall angle.As the tip fillet radius and tooth profile backlash increased,the thinning rate and residual stress decreased.With a tip fillet radius of 0.25 mm and a tooth profile backlash of 0.19 mm,the flow channel achieved an approximately right-angled sidewall,a maximum thinning rate of 7.7%,a 29.6%reduction in maximum residual stress,and maximum and average residual stress imbalance values of 7.1%and 3.2%,respectively.This study proposes a new design method for a right-angled sidewall runner roller gear profile,facilitating the roll forming of metal BPPs with right-angled sidewalls and minimal thinning.This method provides theoretical support for the large-scale application of roll forming in the manufacture of PEMFC BPPs.展开更多
Based on probability and statistic, a design method of precision cam profileconcerning the influence of random processing errors is advanced. Combining the design with theprocess, which can be used to predict that cam...Based on probability and statistic, a design method of precision cam profileconcerning the influence of random processing errors is advanced. Combining the design with theprocess, which can be used to predict that cam profiles will be successfully processed or not in thedesign stage, design of the cam can be done by balancing the economization and reliability. Inaddition, an fuzzy deduction method based on Bayers formula is advanced to estimate processingreasonable of the designed precision cam profile, and it take few samples.展开更多
The design rainstorm profile is the basis of scientifically and rationally planning and designing urban drainage system, which can provide scientific theoretical basis and accurate design parameters for municipal cons...The design rainstorm profile is the basis of scientifically and rationally planning and designing urban drainage system, which can provide scientific theoretical basis and accurate design parameters for municipal construction, water and planning departments. In this paper, the minute-minute rainfall process data at Liuzhou National Meteorological Observation Station from 1975 to 2014 were used. Chicago method was used to analyze and study design rainstorm profile in urban district of Liuzhou, and the profiles of the rainfalls lasting for 30 , 60 , 90, 120, 150, and 180 min were obtained. The results showed that the design rainstorm profile with the same duration in each reappearance period was consistent in Liuzhou, and short-time rainfall profile roughly showed single-peak shape. The peak of each short-time design rainstorm profile was almost in 1/3 part of the whole rainfall process, and the intensity of rainfall increased with the prolonging of the recurrence period. The rainfall intensity at the peak in the same reproducing period showed 11 decrease - increase -decrease＂ as the duration increased, and the peak value of rainfall lasting for 120 min was the maximum.展开更多
Baosteel No. 3 BF has been running smoothly and stably for more than 18 years and has become China＇ s longest-life blast furnace, producing many advanced economical and technical indexes. Comprehensive longevity tech...Baosteel No. 3 BF has been running smoothly and stably for more than 18 years and has become China＇ s longest-life blast furnace, producing many advanced economical and technical indexes. Comprehensive longevity technology has been developed in terms of the design, operation, and maintenance of the No. 3 BF during the prolonged period of research and practice. To obtain stable and smooth operation and to prolong the campaign life, the following measures have been taken： appropriate designing of the furnace profile and cooling system; improving raw material quality and optimizing the operating system; improving the cooling intensity and water quality;and adopting various longevity maintenance measures to ensure the safety of the body and the hearth temperature.展开更多
文摘Cam profiles play an important part in the performance of cam mechanisms. Syntheses of cam profile designs and dynamics of cam designs are studied at first. Then, a cam profile design optimization model based on the six order classical spline and single DOF(degree of freedom) dynamic model of single-dwell cam mechanisms is developed. And dynamic constraints such as jumps and vibrations of followers are considered. This optimization model, with many advantages such as universalities of applications, conveniences to operations and good performances in improving kinematic and dynamic properties of cam mechanisms, is good except for the discontinuity of jerks at the end knots of cam profiles which will cause vibrations of cam systems. However, the optimization is improved by combining the six order classical spline with general polynomial spline which is the so-called "trade-offs". Finally, improved optimization is proven to have a better performance in designing cam profiles.
基金Supported by Major Special Projects of Public Bidding in Shanxi Province of China(Grant No.20201101020)Central Guidance on Local Science and Technology Development Fund Project of China(Grant No.YDZJSX2022A053)Open Fund Subjectof National Key Laboratory of Material Forming and Mold Technology of China(Grant No.P2024-002)。
文摘The forming quality of metal bipolar plate(BPP)flow channels in proton exchange membrane fuel cells(PEMFCs)is a key factor affecting battery performance.A flow channel with straight sidewalls and a low thinning rate can enhance battery output.Roll forming,as a new technology for BPP production,offers advantages such as a low thinning rate and high efficiency.However,existing roll curve design methods struggle to accommodate both low thinning rates and straight sidewall angles simultaneously.This study aims to develop flow channels with right-angled sidewalls,which provide benefits such as a low thinning rate,reduced residual stress,and high accuracy.A roller tooth profile was designed to achieve a flow channel with right-angled sidewalls and minimal thinning.Simulations and experiments were conducted to validate the feasibility of this novel design method for the roll forming process.The study investigated the effects of roller tooth parameters on sidewall angle,thinning rate,and residual stress.A multifactor evaluation method was developed to optimize the tip fillet radius and the tooth profile backlash of the roller.The results indicated that the tip fillet radius and the tooth profile backlash were negatively correlated with the sidewall angle.As the tip fillet radius and tooth profile backlash increased,the thinning rate and residual stress decreased.With a tip fillet radius of 0.25 mm and a tooth profile backlash of 0.19 mm,the flow channel achieved an approximately right-angled sidewall,a maximum thinning rate of 7.7%,a 29.6%reduction in maximum residual stress,and maximum and average residual stress imbalance values of 7.1%and 3.2%,respectively.This study proposes a new design method for a right-angled sidewall runner roller gear profile,facilitating the roll forming of metal BPPs with right-angled sidewalls and minimal thinning.This method provides theoretical support for the large-scale application of roll forming in the manufacture of PEMFC BPPs.
基金This project is supported by Significant Project Foundation of National 863 Program, China.
文摘Based on probability and statistic, a design method of precision cam profileconcerning the influence of random processing errors is advanced. Combining the design with theprocess, which can be used to predict that cam profiles will be successfully processed or not in thedesign stage, design of the cam can be done by balancing the economization and reliability. Inaddition, an fuzzy deduction method based on Bayers formula is advanced to estimate processingreasonable of the designed precision cam profile, and it take few samples.
基金Supported by Scientific Research and Technology Development Plan Project of Liuzhou City in 2017(2017BH30301)Self-supporting Scientific Research Project of Liuzhou Meteorological Bureau in 2016
文摘The design rainstorm profile is the basis of scientifically and rationally planning and designing urban drainage system, which can provide scientific theoretical basis and accurate design parameters for municipal construction, water and planning departments. In this paper, the minute-minute rainfall process data at Liuzhou National Meteorological Observation Station from 1975 to 2014 were used. Chicago method was used to analyze and study design rainstorm profile in urban district of Liuzhou, and the profiles of the rainfalls lasting for 30 , 60 , 90, 120, 150, and 180 min were obtained. The results showed that the design rainstorm profile with the same duration in each reappearance period was consistent in Liuzhou, and short-time rainfall profile roughly showed single-peak shape. The peak of each short-time design rainstorm profile was almost in 1/3 part of the whole rainfall process, and the intensity of rainfall increased with the prolonging of the recurrence period. The rainfall intensity at the peak in the same reproducing period showed 11 decrease - increase -decrease＂ as the duration increased, and the peak value of rainfall lasting for 120 min was the maximum.
文摘Baosteel No. 3 BF has been running smoothly and stably for more than 18 years and has become China＇ s longest-life blast furnace, producing many advanced economical and technical indexes. Comprehensive longevity technology has been developed in terms of the design, operation, and maintenance of the No. 3 BF during the prolonged period of research and practice. To obtain stable and smooth operation and to prolong the campaign life, the following measures have been taken： appropriate designing of the furnace profile and cooling system; improving raw material quality and optimizing the operating system; improving the cooling intensity and water quality;and adopting various longevity maintenance measures to ensure the safety of the body and the hearth temperature.
