| 摘要 |
<p>The device (13) has a connection unit connecting a tube (28) at the interior of one of upper ends (11, 12) of semi-arches (7, 8). A spacing unit spaces the ends, and comprises a threaded rod (16) cooperating with gripping units (14, 15). The threaded rod is equipped in median zone of a rotational operating unit (21). The gripping units are integrated to the exterior of the ends, and comprise interior threads in inverse rotational direction from one gripping unit to another gripping unit. The threads cooperate with corresponding threads (19, 20) of the rod, respectively.</p> |
