永磁直驱式艾萨磨机搅拌盘与筒壁间距对磨矿性能的影响

为探究永磁直驱式艾萨磨机搅拌盘与筒壁间距对矿物颗粒研磨效果的影响规律,采用工程离散元法(EDEM)对磨机内磨矿介质运动分布情况进行数值模拟,分析搅拌盘与筒壁不同间距对磨矿效果的影响规律,通过模拟结果确定磨机内磨矿介质运动分布情况和最佳搅拌盘与筒壁间距。研究结果表明:磨矿介质在靠近搅拌盘穿孔与搅拌盘边缘位置研磨效果最好,但磨机内存在研磨不均匀的现象;随着搅拌盘与筒壁间距的不断增大,磨矿介质平均速度、平均碰撞能、磨机消耗功率呈逐渐减小趋势,而磨矿介质碰撞次数呈先增大后减小的趋势,综合考虑磨矿介质碰撞频率与能效比等因素,确定搅拌盘与筒壁的最佳间距为18 mm。

转速和搅拌盘结构对卧式搅拌磨粉磨效率的影响

以?230 mm×338 mm卧式搅拌磨为研究对象,采用EDEM软件对不同转速、不同搅拌盘结构型式的搅拌磨粉磨效率进行了研究。根据仿真结果和试验验证得出:相同转速下,梯形齿盘的卧式搅拌磨的粉磨效率明显高于锯齿形盘和普通圆盘;相同结构的搅拌盘,其粉磨效率并不会随着转速的提高而持续提高,并对仿真结果进行了验证分析。

支盘水泥搅拌桩复合路基的工程应用研究

支盘水泥搅拌桩复合路基与等截面水泥搅拌桩复合路基相比,在提高承载力和减少工后沉降方面具有明显的优越性。为了便于这种新型的复合路基形式在高等级公路软基处理中的应用,以沉降等效为控制指标,给出了两种桩型在复合路基中等效桩长和桩间距之间的对应关系表达式。借助工程实例的有限元数值分析和实测值沉降的对比,论证了支盘水泥搅拌桩复合路基的优越性和对应关系表达式的可靠性。结果表明:对于均质软土层可选择设置2个支盘,中心分别布置在0.55倍和0.85倍桩长的深度位置,对于含夹层的软土层可优先选择性质较好的土层设置支盘。以沉降量为控制指标,支盘水泥搅拌桩与等截面水泥搅拌桩的桩长存在线性对应关系,桩间距存在指数函数对应关系。

支盘水泥搅拌桩的单桩承载性能研究

为了研究支盘水泥搅拌桩单桩承载性能,利用Plaxis 3D有限元软件,建立单桩静载模型,模拟了常规水泥搅拌桩与支盘水泥搅拌桩在不同荷载条件下的加载情况,通过沉降曲线、应变云图、塑性区的分析和对比,结果表明:支盘水泥搅拌桩能够有效降低复合地基沉降量,提高桩土共同作用的能力,荷载水平越高,支盘水泥搅拌桩沉降降低效果越明显;支盘水泥搅拌桩的桩周土应变分布更加均匀,对于桩周土的承载力利用效率远高于常规水泥搅拌桩,支盘的存在有利于减少局部应变集中现象的产生。支盘的荷载分担比例随着桩顶荷载的增加而增加,在240kN至1440kN范围内,支盘总荷载分担比例均值为45.9%,当荷载提高至2400kN时,支盘总荷载分担比例达到56.7%。支盘水泥搅拌桩承载性能的提高主要是通过支盘对荷载的分担作用实现的,并有效减小桩侧摩阻力和桩端阻力的荷载分担比例,这部分荷载通过支盘转移至盘下土体。

立盘过滤机改进方案的探讨

本文主要从立盘结构、搅拌方式、卸料方式、传动方式及滤布选用等几方面进行深入分析,找出了影响立盘过滤机过滤效率的几种因素,提出相应的改进措施,并对一台立盘过滤机的改造效果进行分析,提出了针对性意见。

Metallurgical behavior and variation of vibro-acoustic signal during preheating assisted friction stir welding between AA6061-T6 and AA7075-T651 alloys

The present work investigated the effects of pin profiles(cylindrical and square),pin eccentricity(0.5 mm and 1 mm)in cylindrical tool and preheating(secondary heating)on metallurgical behavior,variation of vibro-acoustic signal pattern and joint strength during friction stir welding(FSW)between AA6061-T6 and AA7075-T651 alloys.The eccentric tool pins were observed to provide good flowability and intermixing between dissimilar metals,increased the size of stir zone,and the grains in stir zone were sufficiently finer with eccentric tool pin than concentric pin.The magnitude of vibro-acoustic signal increased when shoulder plunging started and drop in signal was noted when the tool shoulder reached its desired depth.The signal magnitude was noted to be higher in welding stage compared to tool plunging stage as the tool took in fresh material during tool movement along the weld path.Preheating the workpiece prior to pin plunging and during welding notably influenced the flow behavior and mixing pattern,and the grains in stir zone were slightly coarser than those in specimen without preheating.Significant reduction in the magnitude of the signal was also observed after preheating.Tensile and flexural strength of joints were also improved slightly when additional heating was employed.