网格划分求助

初学者，学习塔筒开洞处网格不回画 ，现将命令流贴出，请高手出手。看如何续写命令流，使网格好看。如图
[img]file:///C:\Users\Administrator\AppData\Roaming\Tencent\Users\137244868\QQ\WinTemp\RichOle\8XTPX4E0]5UPB50_VVA[TEL.jpg[/img]
finish
/clear
/prep7
et,1,shell181 !定义单元类型，筒
mp,ex,1,2e11 !弹性模量筒
mp,prxy,0.3 !泊松比
mp,dens,1,7850 !密度筒
k,1,,4-0.1, !4是底面直径，0,1是壁厚
k,2,,4
k,3,65,2-0.1 !65是塔筒高度，2是顶面直径
k,4,65,2
a,1,2,4,3!建立面
k,100,
k,101,65
VROTAT,all, , , , , , 100, 101, ,2
vadd,all !布尔交运算
wpoffs,2,, !工作平面移到2,0,0
csys,4 !以工作平面为坐标系
cyl4,0,0,0.75!在工作平面（x，y）创建半径为0.75的圆面
cyl4,2,0,0.75
rectng,,2,-0.75,0.75 !两角（左下、右上）生成矩形
aadd,1,6,11!布尔交运算
vext,12,,,,,5
vsbv,3,1
wpoffs,3,,
wprot,0,0,270 !绕Y轴旋转270度wprota，thxy，thyz，thzx
vsbw,all
wpoffs,0,0,4
vsbw,all
lesize,9,,,20
lesize,10,,,20
lesize,13,,,20
lesize,14,,,20
lesize,11,,,20
lesize,12,,,20
lesize,15,,,20
lesize,16,,,20
lesize,19,,,20
lesize,22,,,20
lesize,23,,,20
lesize,24,,,20
lesize,6,,,20
lesize,30,,,20
lesize,31,,,20
lesize,32,,,20
lesize,17,,,50
lesize,18,,,50
lesize,20,,,50
lesize,21,,,50
lesize,33,,,20
lesize,34,,,20
lesize,53,,,20
lesize,54,,,20
lesize,2,,,5
lesize,8,,,5
lesize,4,,,5
lesize,29,,,5
lesize,7,,,2
lesize,3,,,2
lesize,5,,,2
lesize,1,,,2
asel,u,area,,27,28,1
asel,u,area,,17,22,1
mshape,1,3d !划分网格
mshkey,0
amesh,all
[img]file:///C:\Users\Administrator\AppData\Roaming\Tencent\Users\137244868\QQ\WinTemp\RichOle\8XTPX4E0]5UPB50_VVA[TEL.jpg[/img]