双压辊在减少气泡不良中的应用

轮胎的制造工艺复杂,半成品种类繁多,制工具多样化,生产过程中容易出现一些质量问题.该文从气泡产生的部位入手,分析了轮胎生产时成型过程中气泡发生的原因,介绍了双压辊的使用在减少气泡过程中发挥的作用及其效果。

双均匀压辊的压轧效果探究

对均匀压辊和非均匀压辊的压轧效果进行比较,包括压印和织物出机后CPI,得出均匀压辊的压轧效果优于非均匀压辊;再对双均匀压辊的参数,包括主动辊压力设定、主动辊和从动辊的组合硬度进行了探究性试验,得出最优参数是:第一组压辊的压力为4Bar、主/从动辊硬度为100/90,第二组压辊的压力为3Bar、主/从动辊硬度为95/85。

西瓜直插式嫁接砧木夹持与压苗机构设计与试验

针对西瓜直插式嫁接砧木在生长点去除前定位与处理的损伤问题,以葫芦苗为试验对象,在葫芦苗物理特性分析的基础上,设计一种砧木夹持与压苗机构。砧木夹持与压苗机构通过气囊的膨胀与收缩完成砧木苗的夹取与松开工作,解决传统夹苗机构伤苗现象;采用前后对称的双压辊式压苗机构,解决压苗过程中易造成子叶根部折断的问题。对压苗机构的运动进行静力学分析,并运用ADAMS运动学仿真软件对压苗机构进行分析,结果表明:气缸速度为40~60 mm/s时,后压辊位移曲线较平稳,无明显波动。通过对150株葫芦苗进行砧木夹持与压苗试验,验证可知夹持损伤率和压苗损伤率均为0%,砧木夹持与压苗机构结构合理。该研究可为蔬菜嫁接机的设计提供参考。

Dynamic analysis of double racks gear 3D roll forming machine

3 D roll-forming for high strength steel sheets is a new technology at present.Double racks gear 3D roll forming machine developed by our research group can be used to perform variable cross section roll forming for high strength steel.In the paper,a dynamic model of 8-DOF double rack gear 3D roll-forming machine is established by the method of Lagrange equation.The expression of the angle acceleration of the system response is obtained by solving the dynamic equations.Through an actual engineering example,the dynamical characters of the 3D roll forming machine are revealed.The results can support the design of 3D roll forming machine.Meanwhile,the research will play an active role in the development of control system.

Dynamic modeling of twin roll casting AZ41 magnesium alloy during hot compression processing

A dynamic material model of Mg-4.51Al-1.19Zn-0.5Mn-0.5Ca(AZ41,mass fraction,%)magnesium alloy was put forward.The results show that the dynamic material model can characterize the deformation behavior and microstructure evolution and describe the relations among flow stress,strain,strain rates and deformation temperatures.Statistical analysis shows the validity of the proposed model.The model predicts that lower deformation temperature and higher strain rate cause the sharp strain hardening. Meanwhile,the flow stress curve turns into a steady state at high temperature and lower strain rate.The moderate temperature of 350 ℃and strain rate of 0.01 s-1 are appropriate to this alloy.

Effect of twinning on flow stress during initial stage of hot compression of twin roll cast Mg-5.51Zn-0.49Zr alloy

A Thermecmastor-Z hot deformation simulator,optical microscopy,XRD and TEM were employed to characterize the flow stress behavior and microstructure of twin roll cast ZK60 magnesium alloy during initial stage of hot compression at elevated temperature of 300 ℃ and 400 ℃ and a given strain rate of 10-2s-1.The results suggest that flow stress drop during initial stage of hot compression at 300℃,generally led by dynamic recrystallization,is attributed to twinning,correspondingly to dynamic recrystallization as deformation temperature is raised to 400 ℃.

Microstructure comparison of ZK60 alloy under casting,twin roll casting and hot compression

The microstructures of ZK60 alloy under conventional direct as-casting (DC),twin roll casting (TRC) and twin roll casting followed by hot compression (TRC-HC) were analyzed by optical morphology (OM),electron backscatter diffraction (EBSD) and X-ray diffraction (XRD).The deformation condition of hot compression is 350 ℃,0.1 s?1.The microstructural evolution under TRC-HC deformation followed by annealing at different temperatures and time was discussed.The results show that TRC provides more modified microstructure compared with DC.Twins are found in TRC processing;dynamic recrystallization (DRX),shear bands and twins are found in TRC-HC.A short annealing time has little effect on hardness,while during a long time annealing,it is found that low annealing temperatures increase the micro-hardness and high temperature decreases it.