\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage{pgfplots}
\pgfplotsset{compat=1.8}
\begin{document}
  \fbox{%
  \begin{tikzpicture}
    \begin{axis}[axis equal,scale=2]
      \addplot3[surf,samples=9,domain=-1:1,y domain=0:2*pi,z buffer=sort]
         ({cos(deg(y)) * (1 + x/2 * cos(deg(y)/2))},
         {sin(deg(y)) * (1 + x/2 * cos(deg(y)/2))},
         {x/2 * sin(deg(y)/2)});
    \end{axis}
  \end{tikzpicture}}

  \fbox{%
  \begin{tikzpicture}
    \begin{axis}[axis equal,scale=2,axis lines=none]
      \addplot3[surf,samples=9,domain=-1:1,y domain=0:2*pi,z buffer=sort]
         ({cos(deg(y)) * (1 + x/2 * cos(deg(y)/2))},
         {sin(deg(y)) * (1 + x/2 * cos(deg(y)/2))},
         {x/2 * sin(deg(y)/2)});
    \end{axis}
  \end{tikzpicture}}
  \fbox{%
  \begin{tikzpicture}
    \begin{axis}[axis equal,scale=2,axis lines=none,clip=false]
      \addplot3[surf,samples=9,domain=-1:1,y domain=0:2*pi,z buffer=sort]
         ({cos(deg(y)) * (1 + x/2 * cos(deg(y)/2))},
         {sin(deg(y)) * (1 + x/2 * cos(deg(y)/2))},
         {x/2 * sin(deg(y)/2)});
    \end{axis}
  \end{tikzpicture}}

\end{document} 
