xmin:=0
xmax:=Pi
ymin:=0
ymax:=6*Pi
xxx[x_,y_]:=y/18*Sin[x]*Cos[y]
yyy[x_,y_]:=y/18*Sin[x]*Sin[y]
zzz[x_,y_]:=y/18*Cos[x]+y/6
ParametricPlot3D[{yyy[x,y],-xxx[x,y],zzz[x,y]},{x,xmin,xmax},{y,ymin,ymax},PlotPoints->{15,51},Shading->False]
