Friction self-piercing riveting(F-SPR)process based on a pip die has been invented to solve the cracking problems in riveting high-strength and low-ductility light metals,such as magnesium alloys,cast aluminum,and 7 s...Friction self-piercing riveting(F-SPR)process based on a pip die has been invented to solve the cracking problems in riveting high-strength and low-ductility light metals,such as magnesium alloys,cast aluminum,and 7 series aluminum alloys.In this paper,in order to solve quality issues caused by the misalignment between rivet and pip-die in F-SPR,a flat-die based F-SPR process was proposed and employed to join 1.27 mm-thick AA6061-T6 to 3 mm-thick AZ31B.The results indicate that a 1.0 mm die distance is effective to avoid rivet upset and insufficient flaring.As the feed rate increases,the heat input in the whole process decreases,resulting in a larger riveting force,which in turn increases both the bottom thickness and interlock amount.Besides,solid-state bonding,including Al-Mg intermetallic compounds(IMCs),Al-Mg mechanical mixture,and Al-Fe atom interdiffusion was observed at the joint interfaces.The upper Al layer was softened,but the lower Mg layer was hardened,and both sheets exhibited a narrowed affected region with the increase of feed rate,while the rivet hardness shows no obvious change.Three fracture modes appeared accompanying the variations in lap-shear strength and energy absorption as the feed rate increased from 2 mm/s to 8 mm/s.Finally,the F-SPR process using a flat die was compared to those using a pip die and a flat bottom die to show the advantage of flat die on coping with the misalignment problem.展开更多
中国热带农业区作物剩余物多为香蕉秸秆、椰壳以及甘蔗叶,目前以其为混合原料的固体成型设备研究较少,因此该文设计了一种行星轮式内外锥辊固体燃料平模成型机,描述了该机进料装置、辊压装置以及成型装置等主要部件结构,并对辊压装置进...中国热带农业区作物剩余物多为香蕉秸秆、椰壳以及甘蔗叶,目前以其为混合原料的固体成型设备研究较少,因此该文设计了一种行星轮式内外锥辊固体燃料平模成型机,描述了该机进料装置、辊压装置以及成型装置等主要部件结构,并对辊压装置进行了运动和受力分析,确定了其关键参数。研制样机并进行性能试验,试验结果表明:该机在电动机功率为45 k W、锥辊公转转速为190 r/min、锥辊自转转速为543 r/min、配套喂料输送装置功率为3 k W时,生产率为850 kg/h、颗粒燃料成型率为96.5%、质量密度为1.25 g/cm3、成型后含水率为2.82%、机械耐久性为96.74%,符合生物质颗粒燃料成型要求。整机工作过程中噪音低,经济效益与生态效益明显,为中国热带地区固体燃料成型机的发展与推广提供了参考。展开更多
基金financial support of the National Natural Science Foundation of China(Grant Nos.52025058 and U1764251)。
文摘Friction self-piercing riveting(F-SPR)process based on a pip die has been invented to solve the cracking problems in riveting high-strength and low-ductility light metals,such as magnesium alloys,cast aluminum,and 7 series aluminum alloys.In this paper,in order to solve quality issues caused by the misalignment between rivet and pip-die in F-SPR,a flat-die based F-SPR process was proposed and employed to join 1.27 mm-thick AA6061-T6 to 3 mm-thick AZ31B.The results indicate that a 1.0 mm die distance is effective to avoid rivet upset and insufficient flaring.As the feed rate increases,the heat input in the whole process decreases,resulting in a larger riveting force,which in turn increases both the bottom thickness and interlock amount.Besides,solid-state bonding,including Al-Mg intermetallic compounds(IMCs),Al-Mg mechanical mixture,and Al-Fe atom interdiffusion was observed at the joint interfaces.The upper Al layer was softened,but the lower Mg layer was hardened,and both sheets exhibited a narrowed affected region with the increase of feed rate,while the rivet hardness shows no obvious change.Three fracture modes appeared accompanying the variations in lap-shear strength and energy absorption as the feed rate increased from 2 mm/s to 8 mm/s.Finally,the F-SPR process using a flat die was compared to those using a pip die and a flat bottom die to show the advantage of flat die on coping with the misalignment problem.
文摘中国热带农业区作物剩余物多为香蕉秸秆、椰壳以及甘蔗叶,目前以其为混合原料的固体成型设备研究较少,因此该文设计了一种行星轮式内外锥辊固体燃料平模成型机,描述了该机进料装置、辊压装置以及成型装置等主要部件结构,并对辊压装置进行了运动和受力分析,确定了其关键参数。研制样机并进行性能试验,试验结果表明:该机在电动机功率为45 k W、锥辊公转转速为190 r/min、锥辊自转转速为543 r/min、配套喂料输送装置功率为3 k W时,生产率为850 kg/h、颗粒燃料成型率为96.5%、质量密度为1.25 g/cm3、成型后含水率为2.82%、机械耐久性为96.74%,符合生物质颗粒燃料成型要求。整机工作过程中噪音低,经济效益与生态效益明显,为中国热带地区固体燃料成型机的发展与推广提供了参考。
